JP4414795B2 - Black ink stock solution, ink composition, and method for producing the same - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is an ink composition having excellent ink storage stability, high recorded image quality, and excellent image storage stability, and a black ink having excellent storage stability and handleability as a raw material thereof. Regarding the stock solution.

In recent years, with the spread of computers, ink jet printers are widely used for printing on paper, film, cloth and the like not only in offices but also at home.
Ink jet recording methods include a method in which droplets are ejected by applying pressure with a piezo element, a method in which bubbles are generated in heat by generating bubbles in the ink, a method using ultrasonic waves, or a droplet by electrostatic force. There is a method of sucking and discharging. As these inks for inkjet recording, water-based inks, oil-based inks, or solid (melting type) inks are used. Among these inks, water-based inks are mainly used from the viewpoints of production, handleability, odor, safety, and the like.

For the colorant used in these inks for ink jet recording, it has high solubility in solvents, high density recording is possible, hue is good, light, heat, air, ozone, water, Excellent fastness to chemicals, good fixability to image-receiving materials, low bleeding, excellent storage stability as ink, no toxicity, high purity, and low cost It is required to be able to do it. However, it is extremely difficult to search for colorants that meet these requirements at a high level.
Various dyes and pigments have already been proposed and actually used for inkjet, but no colorant that satisfies all the requirements has yet been discovered. Conventionally well-known dyes and pigments having a color index (CI) number are difficult to achieve both hue and fastness required for ink jet recording inks.

As black dyes for inkjet, food black dyes, naphthol direct azo dyes, acidic azo dyes, and the like have been widely known.
Examples of food black dyes include C.I. I. Food Black 1, C.I. I. Food Black 2 is a typical example, and techniques for using these for black ink for inkjet are described in Patent Document 1, Patent Document 2, Patent Document 3, and the like.
Examples of acidic azo dyes include C.I. I. Techniques using Acid Black 2, 31, 52, 140, 187, etc. for inkjet black ink are disclosed in Patent Document 4, Patent Document 5, Patent Document 6, etc., and direct azo dyes include C.I. I. A technique using Direct Black 9, 17, 38, 51, 60, 102, 107, 122, 142, 154, 168, etc. for inkjet black ink is disclosed in Patent Document 7, Patent It is described in Document 8, Patent Document 9, and the like.

The inventors of the present invention have been studying ink jet inks using dyes. However, it has been found that water-based black ink has a problem of low image durability.
As means for improving the image durability of these dyes for black ink, in particular, ozone resistance, the applicants described in Japanese Patent Application Nos. 2002-281723 and 2003-334061 that the oxidation potential of the dye is increased. Propose in the book. However, among these dyes with a high oxidation potential, the stability in an aqueous solution state, in particular, the stability in a high pH region is poor. It turns out that there is something to happen.
In addition, when an ink composition is prepared, if a dye dissolved in a high concentration is used, handling properties in the manufacturing process are extremely advantageous. However, if the pH is lowered too much in order to improve ink storage stability, There was a problem that the container for storing the density ink was easily corroded.

JP-A-2-36276 JP-A-2-233382 JP-A-2-233378 JP 60-108481 A JP-A-2-36277 JP-A-2-36278 JP-A-56-139568 JP-A 61-285275 JP-A-3-106974

  The problem to be solved by the present invention is an ink composition having excellent storage stability, no hue, weather resistance, water resistance and image quality defects, and a storage stability and handling property as a raw material of the ink composition. An excellent black ink stock solution is provided.

一般式（４−１）及び（４−２）中、Ａ ₁ はイオン性親水性基が置換された芳香族基又は複素環基を表し、Ｒ ₁₀ 及びＲ ₁₁ は、各々独立に、水素原子、脂肪族基、芳香族基、複素環基、アシル基、アルコキシカルボニル基、アリールオキシカルボニル基、カルバモイル基、アルキルまたはアリールスルホニル基、スルファモイル基を表し、Ｒ ₁₂ 、Ｒ ₁₃ 及びＲ ₁₄ は、各々独立に、水素原子、ハロゲン原子、脂肪族基、芳香族基、複素環基、シアノ基、カルボキシル基、カルバモイル基、アルコキシカルボニル基、アリールオキシカルボニル基、複素環オキシカルボニル基、アシル基、ヒドロキシ基、アルコキシ基、アリールオキシ基、複素環オキシ基、シリルオキシ基、アシルオキシ基、カルバモイルオキシ基、アルコキシカルボニルオキシ基、アリールオキシカルボニルオキシ基、アミノ基、アシルアミノ基、ウレイド基、スルファモイルアミノ基、アルコキシカルボニルアミノ基、アリールオキシカルボニルアミノ基、アルキルもしくはアリールスルホニルアミノ基、複素環スルホニルアミノ基、ニトロ基、アルキルもしくはアリールチオ基、複素環チオ基、アルキルもしくはアリールスルホニル基、複素環スルホニル基、アルキルもしくはアリールスルフィニル基、複素環スルフィニル基、スルファモイル基又はスルホ基を表し、Ｒ ₂₅ 及びＲ ₂₆ は、各々独立に、水素原子、脂肪族基、芳香族基、複素環基、アシル基、アルコキシカルボニル基、アリールオキシカルボニル基、カルバモイル基、アルキルもしくはアリールスルホニル基、またはスルファモイル基を表し、Ｚ ₁ はハメットの置換基定数σｐ値が０．２０以上の電子吸引性基を表す。
２）前記アゾ染料は、λｍａｘが５００ｎｍから７００ｎｍにあり、かつ吸光度１．０に規格化した希薄溶液の吸収スペクトルにおける半値幅が１００ｎｍ以上である染料を少なくとも１種含むことを特徴とする上記１）記載のブラックインク原液。
３）前記ｐＨが６〜８であることを特徴とする上記１）または２）に記載のブラックインク原液。
４）更にｐＨ調整剤を含有することを特徴とする上記１）〜３）の何れかに記載のブラックインク原液。
５）前記ｐＨ調整剤は、有機塩基、無機塩基、有機酸、及び無機酸から選択されることを特徴とする上記４）に記載のブラックインク原液。
６）更に防腐剤を含有することを特徴とする上記１）〜５）の何れかに記載のブラックインク原液。
７）前記防腐剤は、重金属イオンを含有する無機物、第４級アンモニウム塩、フェノール誘導体、フェノキシエーテル誘導体、複素環化合物、酸アミド類、カルバミン酸、カルバメート類、アミジン・グアニジン類、ピリジン類、ジアジン類、トリアジン類、ピロール・イミダゾール類、オキサゾール・オキサジン類、チアゾール・チアジアジン類、チオ尿素類、チオセミカルバジド類、ジチオカルバメート類、スルフィド類、スルホキシド類、スルホン類、スルファミド類、抗生物質類、デヒドロ酢酸ナトリウム、安息香酸ナトリウム、ｐ−ヒドロキシ安息香酸エチルエステル、およびその塩からなる群から選択されることを特徴とする上記６）に記載のブラックインク原液。
８）上記１）〜７）の何れかに記載のブラックインク原液を含有し、かつｐＨが７〜９であることを特徴とするインク組成物。
９）インクジェット記録に用いることを特徴とする上記８）記載のインク組成物。
１０）上記１）〜７）の何れかに記載のブラックインク原液を用いることにより上記８）または９）記載のインク組成物を得ることを特徴とするインク組成物の製造方法。 The problems of the present invention can be solved by the following means.
1) An azo dye represented by the following general formula (4-1) or (4-2) and having an oxidation potential nobler than 1.0 V (vs SCE) is contained in the medium, and the pH is 3. A black ink stock solution characterized by being from 0 to 9.0.

In general formulas (4-1) and (4-2), A ₁ represents an aromatic group or heterocyclic group substituted with an ionic hydrophilic group, and R ₁₀ and R ₁₁ are each independently a hydrogen atom. Represents an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl or arylsulfonyl group, a sulfamoyl group, and R ₁₂ , R ₁₃ and R ₁₄ each represents Independently, hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxy group , Alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, Lilleoxycarbonyloxy group, amino group, acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkyl or Represents an arylthio group, a heterocyclic thio group, an alkyl or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, and R ₂₅ and R ₂₆ each independently represents hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl or arylsulfonyl group or a sulfamoyl group,, Z ₁ is Hame' Represents an electron withdrawing group having a substituent constant σp value of 0.20 or more.
2) The azo dye comprises at least one dye having a λmax of 500 nm to 700 nm and a half-value width of 100 nm or more in an absorption spectrum of a diluted solution normalized to an absorbance of 1.0. ) Black ink stock solution as described.
3) The black ink stock solution according to 1) or 2) above, wherein the pH is 6-8 .
4) The black ink stock solution according to any one of 1) to 3 ) above, further comprising a pH adjusting agent.
5 ) The black ink stock solution as described in 4 ) above, wherein the pH adjuster is selected from an organic base, an inorganic base, an organic acid, and an inorganic acid.
6 ) The black ink stock solution according to any one of 1) to 5 ) above, further comprising a preservative.
7 ) The preservatives include inorganic substances containing heavy metal ions, quaternary ammonium salts, phenol derivatives, phenoxy ether derivatives, heterocyclic compounds, acid amides, carbamic acids, carbamates, amidine / guanidines, pyridines, diazines. , Triazines, pyrrole / imidazoles, oxazole / oxazines, thiazole / thiadiazines, thioureas, thiosemicarbazides, dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics, dehydroacetic acid 6. The black ink stock solution according to 6 ) above, which is selected from the group consisting of sodium, sodium benzoate, p-hydroxybenzoic acid ethyl ester, and salts thereof.
8 ) An ink composition comprising the black ink stock solution according to any one of 1) to 7 ) above and having a pH of 7 to 9.
9 ) The ink composition as described in 8 ) above, which is used for ink jet recording.
10 ) A method for producing an ink composition, wherein the ink composition according to 8 ) or 9 ) is obtained by using the black ink stock solution according to any one of 1) to 7 ).

The black ink stock solution of the present invention (hereinafter also referred to as “ink stock solution”) is excellent in ozone resistance and storage stability by using a specific azo dye and adjusting to a specific pH. is there. Further, corrosion of a metal container such as stainless steel for storing the ink stock solution can be effectively prevented.
In addition, the ink stock solution of the present invention is superior in handleability in the production process and can produce a stable quality ink composition, rather than preparing an ink composition from a dye.
Furthermore, since the ink stock solution of the present invention can use a solution before it is made into a powder in the purification process of dye synthesis, it can contribute to cost reduction in the production of the ink composition.
Further, the ink for ink jet recording prepared from the ink stock solution of the present invention is excellent in ejection stability because rust of the nozzle is prevented and the solubility of the dye is improved.

The ink stock solution of the present invention is represented by the general formula (4-1) or (4-2), has an oxidation potential containing a specific azo dye in a medium, and has a pH of 3.0 to 9.0. Preferably it is 5.5-9, More preferably, it is 6-8, but other matters are also described in this specification for reference.
In the present invention, the ink stock solution means a dye concentration higher than that of the ink composition (hereinafter also referred to as “ink”), and the dye concentration of the ink stock solution is preferably 1 to 50% by mass, and more preferably. Is 5 to 40% by mass, particularly preferably 10 to 30% by mass.

The ink stock solution of the present invention may be an azo dye and a medium alone or may contain other various components described later. The concentration of components other than the dye may be higher or lower than that of the ink composition, and is appropriately selected.
The medium is a solvent having a function of dissolving and / or dispersing the dye and other components. In addition, these solvents generally have various functions other than the above functions, as will be described later.
As components other than the dye, it is preferable to contain a pH adjusting agent and a preservative. These components are adjusted so as not to be added to the ink stock solution as described in the method for producing an ink composition using the ink stock solution described later, and the manufacturing process can be simplified and stable. This is preferable because a quality ink composition can be produced. However, if desired, these components may be added during the production of the ink composition.
Examples of the pH adjuster include basic organic bases and inorganic bases, and acidic bases such as organic acids and inorganic acids.
Basic compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium phosphate, sodium monohydrogen phosphate, etc. Inorganic compounds and aqueous ammonia, methylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, piperidine, diazabicyclooctane, diazabicycloundecene, pyridine, quinoline, picoline, lutidine, collidine, etc. It is also possible to use alkali metal salts of organic acids such as organic bases such as lithium benzoate and potassium phthalate.
Examples of acidic compounds include inorganic compounds such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, sodium hydrogen sulfate, potassium hydrogen sulfate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, acetic acid, tartaric acid, benzoic acid, trifluoroacetic acid. Organic compounds such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, saccharic acid, phthalic acid, picolinic acid and quinolinic acid can also be used.

Ink stock solutions may cause problems with the formation of insoluble matter due to decay. In order to prevent this, it is preferable to add a preservative to the ink stock solution.
Various preservatives that can be used in the present invention can be used.
Examples of the preservative include inorganic preservatives (such as silver ion-containing substances) and salts containing heavy metal ions. Organic preservatives include quaternary ammonium salts (tetrabutylammonium chloride, cetylpyridinium chloride, benzyltrimethylammonium chloride, etc.), phenol derivatives (phenol, cresol, butylphenol, xylenol, bisphenol, etc.), phenoxyether derivatives (phenoxyethanol) Etc.), heterocyclic compounds (benzotriazole, PROXEL, 1,2-benzisothiazolin-3-one, etc.), acid amides, carbamic acid, carbamates, amidine / guanidine, pyridines (sodium pyridinethione- 1-oxide, etc.), diazines, triazines, pyrrole / imidazoles, oxazoles / oxazines, thiazoles / thiadiazines, thioureas, thiosemicarbazides Dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, p-hydroxybenzoic acid ethyl ester, and salts thereof It can be used. In addition, as the antiseptic, those described in the antibacterial and microscopic handbook (Technical Hall: 1986), the antibacterial and antifungal encyclopedia (edited by the Japanese Society for Antibacterial and Antifungal Society), etc. can be used.
One or more preservatives can be added to the ink stock solution in combination.
Various compounds such as oil-soluble structures and water-soluble structures can be used as these compounds, but water-soluble compounds are preferred.
Among these, at least one preservative is preferably a heterocyclic compound.
In the present invention, when two or more kinds of preservatives are used in combination, the effects of the present invention are more satisfactorily exhibited. For example, the combination of a heterocyclic compound and an antibiotic, the combination of a heterocyclic compound and a phenol derivative, etc. are mentioned preferably. The content ratio in the case of combining two kinds of preservatives is not particularly limited, but the range of preservative A / preservative B = 0.01 to 100 (mass ratio) is preferable.
The amount of the preservative added to the ink stock solution can be used in a wide range, but is preferably 0.001 to 10% by mass, and more preferably 0.1 to 5% by mass.
The ink stock solution is prepared by dissolving in an aqueous medium when the dye is water-soluble, and is prepared by dissolving and / or dispersing in an oleophilic medium and / or aqueous medium when the dye is oil-soluble. It is preferable to do. The aqueous medium is a solvent mainly containing water, and optionally contains an organic solvent such as a water-miscible organic solvent. The lipophilic medium is mainly composed of an organic solvent.

The ink of the present invention contains the above ink stock solution and has a pH of 7 to 9, preferably 7 to 8.
The application of the ink of the present invention is not particularly limited, and is used for printing ink such as inkjet, ink sheet in heat-sensitive recording material, color toner for electrophotography, LCD and display such as PDP, and imaging such as CCD. Although it can be preferably used for the preparation of a color filter used in the element, a dyeing solution for dyeing various fibers, etc., an ink for inkjet recording is particularly preferable.
The ink production method of the present invention is characterized by using the above ink stock solution.
The ink of the present invention should not be limited to the black ink, but can include any color ink by mixing with other dyes or pigments.
The method for producing an ink of the present invention includes a step of producing a desired ink in the above pH range (hereinafter also referred to as a liquid preparation step) using at least an ink stock solution.
The liquid preparation step is a step of preparing the ink stock solution obtained as described above into a specific pH ink and a desired use ink, which may be a final product or an intermediate product. There may be. This liquid preparation step includes at least a step of diluting the ink stock solution with a medium, preferably an aqueous medium. The ink stock solution containing the oil-soluble dye is not particularly limited in the medium used in this dilution step, but is preferably prepared as an aqueous ink by being emulsified and dispersed in an aqueous medium. The medium may contain various components of a necessary concentration, or the components may be added to the ink stock solution separately, or both of them may be combined.
Since the ink produced according to the present invention is produced by using an ink stock solution having a high dye concentration, the solubility of the dye is improved as compared with the ink produced by a normal method, and thus the ejection stability is improved.

  The ink of the present invention preferably contains 0.2 to 20% by mass of all dyes, more preferably 0.5 to 15% by mass.

  When preparing the ink stock solution, it is preferable to add a step of removing solids by filtration. A filtration filter is used for this operation, and a filter having an effective diameter of 1 μm or less, preferably 0.3 μm or less is used as the filtration filter at this time. Various materials can be used as the filter material, but in the case of an ink stock solution of a water-soluble dye, it is preferable to use a filter prepared for an aqueous solvent. Among them, it is particularly preferable to use a jacket type filter made of a polymer material that is difficult to generate dust. As a filtration method, the jacket may be passed by liquid feeding, and either pressure filtration or vacuum filtration can be used.

  Various methods such as dissolution by stirring, dissolution by ultrasonic irradiation, dissolution by shaking and the like can be used as a method for dissolving the dye and other components in the step of preparing the ink stock solution and the preparation step. Of these, the stirring method is particularly preferably used. In the case of stirring, various methods such as fluidized stirring known in the art and stirring using shearing force using an inverted agitator or dissolver can be used. On the other hand, a stirring method using a shearing force with the bottom surface of the container, such as a magnetic stirrer, can also be preferably used.

Next, the oxidation potential of the dye will be described. The oxidation potential indicates the difficulty of oxidation of the dye, and it is known that the higher the oxidation potential, the lower the reactivity with ozone gas that is an electrophile.
The azo dye used in the present invention is a dye having an oxidation potential nobler than 1.0 V (vs SCE) and nobler than 1.1 V (vs SCE) in terms of fastness and fastness to ozone gas. Some dyes are more preferred, and dyes that are noble above 1.15 V (vs SCE) are particularly preferred.

  The oxidation potential value (Eox) of the dye used in the present invention can be easily measured by those skilled in the art. Regarding this method, see, for example, P.I. Delahay, “New Instrumental Methods in Electrochemistry” (published by Interscience Publishers, 1954) J. et al. "Electrochemical Methods" by Bard et al. (Published by John Wiley & Sons in 1980) and "Electrochemical Measurement Method" by Akira Fujishima et al. (Published by Gihodo Publishing Co., Ltd. in 1984).

Specifically, the oxidation potential is 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / in a test sample in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. Dissolve in 1 liter and measure as a value relative to SCE (standard saturated calomel electrode) using cyclic voltammetry or the like. Although this value may be deviated by several tens of mil volts due to the influence of the liquid potential difference or the liquid resistance of the sample solution, the reproducibility of the potential can be ensured by inserting a standard sample (for example, hydroquinone).
In order to uniquely define the potential, in the present invention, measurement is performed in dimethylformamide containing 0.1 mol / liter of tetrapropylammonium perchlorate as a supporting electrolyte (the concentration of the dye is 0.001 mol / liter). The value obtained (vs SCE) is taken as the oxidation potential of the dye.

  The value of Eox represents the ease of transfer of electrons from the sample to the electrode, and the larger the value (the higher the oxidation potential), the less transfer of electrons from the sample to the electrode, in other words, less oxidation. In relation to the structure of the compound, the oxidation potential becomes more noble by introducing an electron withdrawing group, and the oxidation potential becomes lower by introducing an electron donating group. In the present invention, in order to lower the reactivity with ozone as an electrophile, it is desirable to introduce an electron withdrawing group into the dye skeleton to make the oxidation potential more noble.

The azo dye used for the ink stock solution of the present invention has a λmax of 500 nm to 700 nm and a half-value width (Wλ, _1/2 ) in an absorption spectrum of a diluted solution normalized to an absorbance of 1.0, 100 nm or more, preferably 120 nm. It is preferable to contain at least one dye (L) that is not less than 500 nm and more preferably not less than 120 nm and not more than 350 nm.

If this dye (L) alone can achieve high image quality “(good) black” = black that does not depend on the observation light source and any of the color tones of B, G, and R is difficult to emphasize, Although it is possible to use a dye alone as an ink stock solution or an ink raw material, the ink is generally used in combination with a dye that covers a region where the absorption of the dye is low. Usually, in the case of an ink using a dye (L), it is preferably used in combination with a dye (S) having a main absorption (λmax of 350 nm to 500 nm) in the yellow region. Further, it is possible to prepare an ink in combination with other dyes.
The dye (S) can be used in an ink stock solution, but it is preferably mixed and used at the time of ink preparation from the viewpoint of storage stability.

  In the present invention, a black ink satisfying the following conditions is preferable in order to satisfy 1) excellent weather resistance and / or 2) that black balance is not lost even after fading.

First, black square symbols of the JIS code 2223 are printed at 48 points using black ink, and the reflection density (D _vis ) measured by the status A filter (visual filter) is defined as the initial density. An example of a reflection density measuring machine equipped with a status A filter is an X-Rite density measuring machine. Here, when measuring the density of “black”, the measured value by D _vis is used as the standard observation reflection density. From this time (t) until the reflection density (D _vis ) reaches 80% of the initial reflection density value, the printed matter is forcibly faded using an ozone fading tester capable of always generating 5 ppm of ozone. The forced fading rate constant (k _vis ) is obtained from the relational expression “0.8 = exp (−k _vis · t)”.
In the present invention, the rate constant (k _vis ) is 5.0 × 10 ⁻² [hour ⁻¹ ] or less, preferably 3.0 × 10 ⁻² [hour ⁻¹ ] or less, more preferably 1.0 × 10 ^{−. 2} [hour ^-1 ] An ink having the following ^value is prepared.

Further, black square symbols of JIS code 2223 are printed at 48 points using black ink, and this is a density measurement value measured by a status A filter, which is not D _vis but C (cyan), M (magenta), Y ( (Yellow) The reflection densities (D _R , D _G , D _B ) of the three colors are also defined as initial densities. Here, (D _R , D _G , D _B ) indicates (C reflection density by the red filter, M reflection density by the green filter, and Y reflection density by the blue filter). This print is forcibly faded using an ozone fading tester capable of always generating 5 ppm of ozone in accordance with the above method, and each reflection density (D _R , D _G , D _B ) is 80% of the initial density value. Similarly, the forced fading rate constants (k _R , k _G , k _B ) are determined from the time until. When the three rate constants are obtained and the ratio (R) between the maximum value and the minimum value is obtained (for example, when k _R is the maximum value and k _G is the minimum value, R = k _R / k _G ) The ink is prepared so that the ratio (R) is 1.2 or less, preferably 1.1 or less, and more preferably 1.05 or less.

  Note that the “printed matter in which the black square symbol of the JIS code 2223 is printed at 48 points” used above gives an image large enough to cover the aperture of the measuring instrument in order to give a sufficient size for density measurement. It is printed.

  The azo dye (L) used in the present invention is preferably a compound represented by the following general formula (1).

Hereinafter, the dye represented by the general formula (1) will be described.
Formula _{(1): A 1 -N =} N-A 2 -N = N-A 3
In the formula, A ₁ , A ₂ and A ₃ each independently represents an optionally substituted aromatic group or an optionally substituted heterocyclic group. A ₁ and A ₃ are monovalent groups, and A ₂ is a divalent group.
The azo dye represented by the general formula (1) is particularly preferably a dye represented by the following general formula (2).
General formula (2);

In the general formula (2), T ₁ and T ₂ each represent = CR ₁₂ -and -CR ₁₃ =, or either one represents a nitrogen atom and the other represents = CR ₁₂ -or -CR ₁₃ =. .

V ₁ , R ₁₂ and R ₁₃ are each independently a hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group , Heterocyclic oxycarbonyl group, acyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (alkyl Amino group, arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group , Nito Represents a group, an alkyl or arylthio group, a heterocyclic thio group, an alkyl or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, each group being further substituted May be.

R ₁₀ and R ₁₁ are each independently a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkyl or arylsulfonyl group, sulfamoyl group. Each group may further have a substituent.
R ₁₂ and R ₁₀ , or R ₁₀ and R ₁₁ may be bonded to form a 5- to 6-membered ring.
A ₁ and A ₂ are synonymous with those of the general formula (1).

  The azo dye represented by the general formula (2) is preferably a dye represented by the following general formula (3-1) or the following general formula (3-2).

In the general formula (3-1) and the general formula (3-2), R ₁₄ and R ₁₅ have the same meaning as R _{12 in the} general formula (2). A ₁ , R ₁₀ , R ₁₁ , T ₁ , T ₂ , and V ₁ have the same meaning as in the general formula (2).

  Here, the general formula (1), the general formula (2), the general formula (3-1), and the general formula (3-2) (hereinafter, the general formula (3-1) and the general formula (3-2) The term (substituent) used in the description of the general formula (3) when collectively expressed will be described. These terms are common to the explanation of the general formula (4) and the general formula (5) described later.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

  An aliphatic group means an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group, and a substituted aralkyl group. The aliphatic group may have a branch and may form a ring. The number of carbon atoms in the aliphatic group is preferably 1-20, and more preferably 1-16. The aryl part of the aralkyl group and the substituted aralkyl group is preferably phenyl or naphthyl, particularly preferably phenyl. Examples of aliphatic groups include methyl, ethyl, butyl, isopropyl, t-butyl, hydroxyethyl, methoxyethyl, cyanoethyl, trifluoromethyl, 3-sulfopropyl, 4-sulfobutyl, cyclohexyl group, benzyl group, 2-phenethyl Groups, vinyl groups, and allyl groups.

  The monovalent aromatic group means an aryl group and a substituted aryl group. The aryl group is preferably phenyl or naphthyl, particularly preferably naphthyl. The number of carbon atoms in the monovalent aromatic group is preferably 6-20, and more preferably 6-16. Examples of the monovalent aromatic group include phenyl, p-tolyl, p-methoxyphenyl, o-chlorophenyl and m- (3-sulfopropylamino) phenyl. The divalent aromatic group is a divalent version of these monovalent aromatic groups. Examples thereof include phenylene, p-tolylene, p-methoxyphenylene, o-chlorophenylene, and m- (3-sulfo Propylamino) phenylene, naphthylene and the like.

  The heterocyclic group includes a heterocyclic group having a substituent and an unsubstituted heterocyclic group. The heterocyclic ring may be condensed with an aliphatic ring, an aromatic ring or another heterocyclic ring. The heterocyclic group is preferably a 5-membered or 6-membered heterocyclic group, and N, O, and S can be exemplified as the hetero atom of the heterocyclic ring. Examples of the substituent include aliphatic groups, halogen atoms, alkyl and arylsulfonyl groups, acyl groups, acylamino groups, sulfamoyl groups, carbamoyl groups, ionic hydrophilic groups, and the like. Examples of the monovalent heterocyclic group include 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2-benzoxazolyl group and 2-furyl group. The divalent heterocyclic group is a group that has become a bond by removing a hydrogen atom from the monovalent heterocyclic ring.

  The carbamoyl group includes a carbamoyl group having a substituent and an unsubstituted carbamoyl group. Examples of the substituent include an alkyl group. Examples of the carbamoyl group include a methylcarbamoyl group and a dimethylcarbamoyl group.

  The alkoxycarbonyl group includes an alkoxycarbonyl group having a substituent and an unsubstituted alkoxycarbonyl group. As the alkoxycarbonyl group, an alkoxycarbonyl group having 2 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.

  The aryloxycarbonyl group includes an aryloxycarbonyl group having a substituent and an unsubstituted aryloxycarbonyl group. As the aryloxycarbonyl group, an aryloxycarbonyl group having 7 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group.

The heterocyclic oxycarbonyl group includes a heterocyclic oxycarbonyl group having a substituent and an unsubstituted heterocyclic oxycarbonyl group. The heterocyclic oxycarbonyl group is preferably a heterocyclic oxycarbonyl group having 2 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the heterocyclic oxycarbonyl group include a 2-pyridyloxycarbonyl group.
The acyl group includes an acyl group having a substituent and an unsubstituted acyl group. As the acyl group, an acyl group having 1 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the acyl group include an acetyl group and a benzoyl group.

  The alkoxy group includes an alkoxy group having a substituent and an unsubstituted alkoxy group. As an alkoxy group, a C1-C20 alkoxy group is preferable. Examples of the substituent include an alkoxy group, a hydroxyl group, and an ionic hydrophilic group. Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, a methoxyethoxy group, a hydroxyethoxy group, and a 3-carboxypropoxy group.

  The aryloxy group includes an aryloxy group having a substituent and an unsubstituted aryloxy group. The aryloxy group is preferably an aryloxy group having 6 to 20 carbon atoms. Examples of the substituent include an alkoxy group and an ionic hydrophilic group. Examples of the aryloxy group include a phenoxy group, a p-methoxyphenoxy group, and an o-methoxyphenoxy group.

  The heterocyclic oxy group includes a heterocyclic oxy group having a substituent and an unsubstituted heterocyclic oxy group. The heterocyclic oxy group is preferably a heterocyclic oxy group having 2 to 20 carbon atoms. Examples of the substituent include an alkyl group, an alkoxy group, and an ionic hydrophilic group. Examples of the heterocyclic oxy group include a 3-pyridyloxy group and a 3-thienyloxy group.

  The silyloxy group is preferably a silyloxy group substituted with an aliphatic group or aromatic group having 1 to 20 carbon atoms. Examples of the silyloxy group include trimethylsilyloxy and diphenylmethylsilyloxy.

  The acyloxy group includes an acyloxy group having a substituent and an unsubstituted acyloxy group. As the acyloxy group, an acyloxy group having 1 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group.

  The carbamoyloxy group includes a carbamoyloxy group having a substituent and an unsubstituted carbamoyloxy group. Examples of the substituent include an alkyl group. Examples of the carbamoyloxy group include an N-methylcarbamoyloxy group.

  The alkoxycarbonyloxy group includes an alkoxycarbonyloxy group having a substituent and an unsubstituted alkoxycarbonyloxy group. As the alkoxycarbonyloxy group, an alkoxycarbonyloxy group having 2 to 20 carbon atoms is preferable. Examples of the alkoxycarbonyloxy group include a methoxycarbonyloxy group and an isopropoxycarbonyloxy group.

  The aryloxycarbonyloxy group includes an aryloxycarbonyloxy group having a substituent and an unsubstituted aryloxycarbonyloxy group. The aryloxycarbonyloxy group is preferably an aryloxycarbonyloxy group having 7 to 20 carbon atoms. Examples of the aryloxycarbonyloxy group include a phenoxycarbonyloxy group.

The amino group includes an amino group substituted with an alkyl group, an aryl group or a heterocyclic group, and the alkyl group, aryl group and heterocyclic group may further have a substituent. As the alkylamino group, an alkylamino group having 1 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the alkylamino group include a methylamino group and a diethylamino group.
The arylamino group includes an arylamino group having a substituent and an unsubstituted arylamino group. The arylamino group is preferably an arylamino group having 6 to 20 carbon atoms. Examples of the substituent include a halogen atom and an ionic hydrophilic group. Examples of the arylamino group include an anilino group and a 2-chlorophenylamino group.
The heterocyclic amino group includes a heterocyclic amino group having a substituent and an unsubstituted heterocyclic amino group. As the heterocyclic amino group, a heterocyclic amino group having 2 to 20 carbon atoms is preferable. Examples of the substituent include an alkyl group, a halogen atom, and an ionic hydrophilic group.

  The acylamino group includes an acylamino group having a substituent and an unsubstituted acylamino group. The acylamino group is preferably an acylamino group having 2 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the acylamino group include an acetylamino group, a propionylamino group, a benzoylamino group, an N-phenylacetylamino group, and a 3,5-disulfobenzoylamino group.

  The ureido group includes a ureido group having a substituent and an unsubstituted ureido group. The ureido group is preferably a ureido group having 1 to 20 carbon atoms. Examples of the substituent include an alkyl group and an aryl group. Examples of the ureido group include a 3-methylureido group, a 3,3-dimethylureido group, and a 3-phenylureido group.

  The sulfamoylamino group includes a sulfamoylamino group having a substituent and an unsubstituted sulfamoylamino group. Examples of the substituent include an alkyl group. Examples of the sulfamoylamino group include an N, N-dipropylsulfamoylamino group.

  The alkoxycarbonylamino group includes an alkoxycarbonylamino group having a substituent and an unsubstituted alkoxycarbonylamino group. As the alkoxycarbonylamino group, an alkoxycarbonylamino group having 2 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of the alkoxycarbonylamino group include an ethoxycarbonylamino group.

  The aryloxycarbonylamino group includes an aryloxycarbonylamino group having a substituent and an unsubstituted aryloxycarbonylamino group. The aryloxycarbonylamino group is preferably an aryloxycarbonylamino group having 7 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the aryloxycarbonylamino group include a phenoxycarbonylamino group.

  The alkyl and arylsulfonylamino groups include substituted alkyl and arylsulfonylamino groups, and unsubstituted alkyl and arylsulfonylamino groups. As the sulfonylamino group, a sulfonylamino group having 1 to 20 carbon atoms is preferable. Examples of the substituent include an ionic hydrophilic group. Examples of these sulfonylamino groups include a methylsulfonylamino group, an N-phenyl-methylsulfonylamino group, a phenylsulfonylamino group, and a 3-carboxyphenylsulfonylamino group.

  The heterocyclic sulfonylamino group includes a heterocyclic sulfonylamino group having a substituent and an unsubstituted heterocyclic sulfonylamino group. The heterocyclic sulfonylamino group is preferably a heterocyclic sulfonylamino group having 1 to 12 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the heterocyclic sulfonylamino group include a 2-thiophenesulfonylamino group and a 3-pyridinesulfonylamino group.

  The heterocyclic sulfonyl group includes a heterocyclic sulfonyl group having a substituent and an unsubstituted heterocyclic sulfonyl group. The heterocyclic sulfonyl group is preferably a heterocyclic sulfonyl group having 1 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the heterocyclic sulfonyl group include a 2-thiophenesulfonyl group and a 3-pyridinesulfonyl group.

  The heterocyclic sulfinyl group includes a heterocyclic sulfinyl group having a substituent and an unsubstituted heterocyclic sulfinyl group. The heterocyclic sulfinyl group is preferably a heterocyclic sulfinyl group having 1 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the heterocyclic sulfinyl group include a 4-pyridinesulfinyl group.

  The alkyl, aryl and heterocyclic thio groups include substituted alkyl, aryl and heterocyclic thio groups and unsubstituted alkyl, aryl and heterocyclic thio groups. Alkyl, aryl and heterocyclic thio groups are preferably those having 1 to 20 carbon atoms. Examples of the substituent include an ionic hydrophilic group. Examples of the alkyl, aryl and heterocyclic thio groups include a methylthio group, a phenylthio group, and a 2-pyridylthio group.

  The alkyl and arylsulfonyl groups include substituted alkyl and arylsulfonyl groups, unsubstituted alkyl and arylsulfonyl groups. Examples of the alkyl and arylsulfonyl groups include a methylsulfonyl group and a phenylsulfonyl group, respectively.

  Alkyl and arylsulfinyl groups include substituted alkyl and arylsulfinyl groups, unsubstituted alkyl and arylsulfinyl groups. Examples of the alkyl and arylsulfinyl groups include a methylsulfinyl group and a phenylsulfinyl group, respectively.

  The sulfamoyl group includes a sulfamoyl group having a substituent and an unsubstituted sulfamoyl group. Examples of the substituent include an alkyl group. Examples of the sulfamoyl group include a dimethylsulfamoyl group and a di- (2-hydroxyethyl) sulfamoyl group.

Next, general formulas (1), (2) and (3) will be further described.
In the following description, what has already been described applies to the group and the substituent.
In the general formula (1), A ₁ , A ₂ and A ₃ are each independently an optionally substituted aromatic group (A ₁ and A ₃ are monovalent aromatic groups such as an aryl group; A ₂ represents a divalent aromatic group such as an arylene group or an optionally substituted heterocyclic group (A ₁ and A ₃ are monovalent heterocyclic groups; A ₂ is a divalent heterocyclic group). Examples of the aromatic ring include a benzene ring and a naphthalene ring, and examples of the hetero atom of the heterocyclic ring include N, O, and S. The heterocyclic ring may be condensed with an aliphatic ring, an aromatic ring or another heterocyclic ring.
The substituent may be an arylazo group or a heterocyclic azo group. Therefore, the dye represented by the general formula (1) includes trisazo dyes and tetrakisazo dyes.
In addition, at least two of A ₁ , A ₂ and A ₃ are preferably heterocyclic groups.

A preferred heterocyclic group for A ₃ is an aromatic nitrogen-containing 6-membered heterocyclic group. Particularly preferred is the case where A ₃ is an aromatic nitrogen-containing 6-membered heterocyclic group represented by the following general formula P. At this time, the general formula (1) corresponds to the general formula (2).
Formula P;

In the general formula (P), T ₁ and T ₂ each represent = CR ₁₂ -and -CR ₁₃ =, or either one represents a nitrogen atom and the other represents = CR ₁₂ -or -CR ₁₃ =. each = CR ₁₂ -, - represents a CR ₁₃ = is more preferable.
R ₁₀ and R ₁₁ are each independently a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkyl or arylsulfonyl group, sulfamoyl group. Each group may further have a substituent. Preferable substituents represented by R ₁₀ and R ₁₁ include a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkyl or arylsulfonyl group. More preferably, they are a hydrogen atom, an aromatic group, a heterocyclic group, an acyl group, an alkyl or arylsulfonyl group. Most preferably, they are a hydrogen atom, an aryl group, and a heterocyclic group. Each group may further have a substituent.

V ₁ , R ₁₂ and R ₁₃ are each independently a hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, Heterocyclic oxycarbonyl group, acyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (alkylamino) Group, arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group, Nitro group, al Represents a kill or arylthio group, a heterocyclic thio group, an alkyl or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, and each group may be further substituted Good.

Examples of the substituent represented by V ₁ include a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a hydroxy group, an alkoxy group, an aryloxy group, an acyloxy group, a heterocyclic oxy group, an amino group (an alkylamino group, Arylamino group, including heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl and arylthio group, or heterocyclic thio group, more preferably Is a hydrogen atom, halogen atom, alkyl group, hydroxy group, alkoxy group, aryloxy group, acyloxy group, amino group (including alkylamino group, arylamino group, heterocyclic amino group) or acylamino group, and particularly a hydrogen atom An arylamino group and an acylamino group are most preferable. Each group may further have a substituent.

Preferred substituents represented by R ₁₂ and R ₁₃ include a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, a halogen atom, an alkoxycarbonyl group, a carboxyl group, a carbamoyl group, a hydroxy group, an alkoxy group, and a cyano group. be able to. Each group may further have a substituent. R ₁₂ and R ₁₀ , or R ₁₀ and R ₁₁ may combine to form a 5- to 6-membered ring. As the substituent when each substituent represented by A ₁ , R ₁₂ , R ₁₃ , R ₁₀ , R ₁₁ , V ₁ further has a substituent, the substituents mentioned in the above V ₁ , R ₁₀ , R ₁₁ The group can be mentioned. Moreover, it is preferable to further have an ionic hydrophilic group as a substituent at any position on A ₁ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , V ₁ .

  Examples of the ionic hydrophilic group as a substituent include a sulfo group, a carboxyl group, a phosphono group, and a quaternary ammonium group. As the ionic hydrophilic group, a carboxyl group, a phosphono group, and a sulfo group are preferable, and a carboxyl group and a sulfo group are particularly preferable. The carboxyl group, phosphono group, and sulfo group may be in the form of a salt. Examples of counter ions that form a salt include ammonium ions, alkali metal ions (eg, lithium ions, sodium ions, potassium ions), and organic cations. (Examples include tetramethylammonium ion, tetramethylguanidinium ion, tetramethylphosphonium ion), and lithium ion is particularly preferable.

Preferred examples of the heterocyclic ring represented by A ₂ include a thiophene ring, a thiazole ring, an imidazole ring, a benzothiazole ring, and a thienothiazole ring. Each heterocyclic group may further have a substituent. Of these, thiophene rings, thiazole rings, imidazole rings, benzothiazole rings, and thienothiazole rings represented by the following general formulas (a) to (e) are preferable. When A ₂ is a thiophene ring represented by (a) and A ₃ is a structure represented by the general formula P, the general formula (1) corresponds to the general formula (3-1). , A ₂ is a thiazole ring represented by (b), and A ₃ is a structure represented by the general formula P, the general formula (1) corresponds to the general formula (3-2). become.

In the general formulas (a) to (e), R ₁₆ to R ₂₄ represent a substituent having the same meaning as V ₁ , R ₁₂ and R ₁₃ in the general formula P.

  Among the dyes represented by the general formula (3), particularly preferred structures are those represented by the following general formula (4-1) or general formula (4-2) (hereinafter referred to as general formula (4-1). ) And general formula (4-2) are collectively expressed as general formula (4)).

In the formula, Z ₁ represents an electron-withdrawing group having a Hammett's substituent constant σp value of 0.20 or more. Z ₁ is preferably an electron-withdrawing group having a σp value of 0.30 or more, more preferably 0.45 or more, and particularly preferably an electron-withdrawing group of 0.60 or more. It is desirable not to exceed zero.

  Specifically, examples of the electron-withdrawing group having a Hammett substituent constant σp value of 0.60 or more include a cyano group, a nitro group, and an alkylsulfonyl group (for example, a methanesulfonyl group, an arylsulfonyl group (for example, a benzenesulfonyl group)). Can be mentioned.

  In addition to the above, an electron-withdrawing group having a Hammett substituent constant σp value of 0.45 or more includes an acyl group (for example, acetyl group), an alkoxycarbonyl group (for example, dodecyloxycarbonyl group), an aryloxycarbonyl group (for example, m- Chlorophenoxycarbonyl), alkylsulfinyl groups (eg n-propylsulfinyl), arylsulfinyl groups (eg phenylsulfinyl), sulfamoyl groups (eg N-ethylsulfamoyl, N, N-dimethylsulfamoyl), halogenated An alkyl group (for example, trifluoromethyl) can be mentioned.

  As the electron-withdrawing group having a Hammett substituent constant σp value of 0.30 or more, in addition to the above, an acyloxy group (for example, acetoxy), a carbamoyl group (for example, N-ethylcarbamoyl, N, N-dibutylcarbamoyl), halogen Alkoxy group (for example, trifluoromethyloxy), halogenated aryloxy group (for example, pentafluorophenyloxy), sulfonyloxy group (for example, methylsulfonyloxy group), halogenated alkylthio group (for example, difluoromethylthio), 2 An aryl group (eg, 2,4-dinitrophenyl, pentachlorophenyl) substituted with one or more electron-withdrawing groups having a σp value of 0.15 or more, and a heterocycle (eg, 2-benzoxazolyl, 2- Benzothiazolyl, 1-phenyl-2-benzimidazolyl) be able to.

  Specific examples of the electron-withdrawing group having a Hammett substituent constant σp value of 0.20 or more include a halogen atom in addition to the above.

The Z _1, inter alia, an acyl group having 2 to 20 carbon atoms, an alkyloxycarbonyl group having 2 to 20 carbon atoms, a nitro group, a cyano group, an alkylsulfonyl group having 1 to 20 carbon atoms, 6 to 20 carbon atoms An arylsulfonyl group, a carbamoyl group having 1 to 20 carbon atoms, and a halogenated alkyl group having 1 to 20 carbon atoms are preferable. Particularly preferred are a cyano group, an alkylsulfonyl group having 1 to 20 carbon atoms, and an arylsulfonyl group having 6 to 20 carbon atoms, and most preferred is a cyano group.
The Hammett's substituent constant σp value used in the present specification has the same meaning as described in JP-A-2003-306623, [0059] to [0060].

R < ₁₀ >, R < ₁₁ >, R < ₁₂ >, R <_13> , R <_14> in the general formula (4) has the same meaning as in the general formula (3). R ₂₅ and R ₂₆ are each independently a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkyl or arylsulfonyl group, or sulfamoyl group. Represents. Among these, a hydrogen atom, an aromatic group, a heterocyclic group, an acyl group, an alkyl or arylsulfonyl group is preferable, and a hydrogen atom, an aromatic group, and a heterocyclic group are particularly preferable.

Each group described in the general formula (4) may further have a substituent. When each of these groups further has a substituent, examples of the substituent include the substituents described in the general formula (2), the groups exemplified for V ₁ , R ₁₀ and R ₁₁ , and ionic hydrophilic groups. .

Further, the azo dye represented by the general formula (1) is preferably an azo dye having a conjugated π electron in an aromatic ring group that is not directly bonded to an azo group in order to ensure storage stability in an aqueous solution or ink. The aromatic ring group directly bonded to the azo group means the whole aromatic ring group bonded to the azo group, whereas the aromatic ring group not directly bonded to the azo group does not bond directly to the azo group and is an azo dye. Means an aromatic ring group which exists as a substituent on the chromophore constituting R. For example, when a naphthalene ring group is directly bonded to an azo group, the entire naphthalene ring group is regarded as an aromatic ring group directly bonded to the azo group. When a biphenyl group is bonded to an azo group, the phenyl group bonded to the azo group is a directly bonded aromatic ring group, and the other phenyl group is an aromatic ring group that is not directly bonded. The aromatic ring group means an aromatic group or an aromatic heterocyclic group. The aromatic heterocyclic group means a substituent having a hetero atom and showing aromaticity. By having such an aromatic ring group as a substituent, the dye exhibits a preferable associative property and can improve storage stability. The substitution position of the aromatic ring group is preferably R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₂₅ , R ₂₆ in the general formula (4), particularly R ₁₀ , R ₁₁ , R _14. , R ₂₅ and R ₂₆ are preferred.

A ₁ may be either an aromatic group or a heterocyclic group, but is preferably a benzene ring, naphthalene ring, pyridine ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, thiadiazole ring, benzothiazole ring, A benzoisothiazole ring, further a benzene ring, a naphthalene ring, a pyridine ring, a pyrazole ring, an imidazole ring, an isothiazole ring, and a benzothiazole ring, and most preferably a benzene ring and a naphthalene ring.

The particularly preferred combination of substituents as the azo dye represented by the general formula (2) of the present invention is preferably a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, a sulfonyl group, or an acyl group as R ₁₀ and R _11. And more preferably a hydrogen atom, an aryl group, a heterocyclic group or a sulfonyl group, and most preferably a hydrogen atom, an aryl group or a heterocyclic group. However, R ₁₀ and R ₁₁ are not both hydrogen atoms.
V ₁ is preferably a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, an amino group, or an acylamino group, more preferably a hydrogen atom, a halogen atom, an amino group, or an acylamino group, most preferably a hydrogen atom, An amino group and an acylamino group.
Among A ₁ , preferred are a pyrazole ring, an imidazole ring, an isothiazole ring, a thiadiazole ring, and a benzothiazole ring, and further a pyrazole ring and an isothiazole ring, and most preferred is a pyrazole ring.
T ₁ and T ₂ are ═CR ₁₂ — and —CR ₁₃ ═, respectively, and R ₁₂ and R ₁₃ are preferably hydrogen atom, alkyl group, halogen atom, cyano group, carbamoyl group, carboxyl group, hydroxyl group, respectively. , An alkoxy group and an alkoxycarbonyl group, and more preferably a hydrogen atom, an alkyl group, a carboxyl group, a cyano group and a carbamoyl group.

  In addition, with respect to the preferable combination of substituents of the azo dye represented by the general formula (1), a compound in which at least one of various substituents is the above preferable group is preferable, and more various substituents are described above. A compound that is a preferred group is more preferred, and a compound in which all substituents are the preferred groups is most preferred.

  Specific examples of the azo dye represented by the general formula (1) are shown below, but the present invention is not limited to the following examples, and among the following specific examples, a carboxyl group, a phosphono group, and a sulfo group. The group may be in a salt state, and examples of the counter ion forming the salt include ammonium ion, alkali metal ion (eg, lithium ion, sodium ion, potassium ion) and organic cation (eg, tetramethylammonium ion). , Tetramethylguanidinium ion, tetramethylphosphonium). Among these, ammonium ions, organic cations, and lithium ions are preferable, and lithium ions are most preferable.

  The azo dyes represented by the general formulas (1), (2), (3), and (4) can be synthesized by a coupling reaction between a diazo component and a coupler. As a main synthesis method, it can be synthesized by the method described in Japanese Patent Application No. 2002-113460.

  As the dye (S) having a λmax of 350 nm to 500 nm, a yellow dye described later can be used. In the present invention, a yellow pigment can also be used.

  The content of the azo dye represented by the general formula (1) in the ink is preferably 0.2 to 20% by mass, and more preferably 0.5 to 15% by mass.

  Examples of dyes that can be used in the present invention include the following in addition to those described above. A single dye is used in combination in order to adjust the color tone. In the present invention, an ink set composed of a plurality of inks using a plurality of dyes can be used to obtain a full-color image.

  Examples of yellow dyes include phenols, naphthols, anilines, pyrazolones, pyridones, aryl or heteryl azo dyes having open-chain active methylene compounds as coupling components; for example, open-chain active methylene compounds as coupling components. Azomethine dyes; methine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes; And dyes, acridine dyes, acridinone dyes and the like. These dyes may be those that exhibit yellow only after a part of the chromophore is dissociated, in which case the counter cation may be an alkali metal or an inorganic cation such as ammonium, pyridinium, It may be an organic cation such as a quaternary ammonium salt, and further may be a polymer cation having them in a partial structure.

  Examples of magenta dyes include, for example, aryl or heteryl azo dyes having phenols, naphthols, and anilines as coupling components; azomethine dyes having pyrazolones and pyrazolotriazoles as coupling components; Dyes, methine dyes such as oxonol dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, quinone dyes such as naphthoquinone, anthraquinone, anthrapyridone, etc. And ring dyes. These dyes may exhibit magenta only after part of the chromophore is dissociated, and the counter cation in that case may be an alkali metal or an inorganic cation such as ammonium, pyridinium, It may be an organic cation such as a quaternary ammonium salt, and further may be a polymer cation having them in a partial structure.

  Examples of cyan dyes include azomethine dyes such as indoaniline dyes and indophenol dyes; polymethine dyes such as cyanine dyes, oxonol dyes and merocyanine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes and xanthene dyes; phthalocyanine Dyes; anthraquinone dyes; For example, aryl or heteryl azo dyes having phenols, naphthols and anilines as coupling components, and indigo / thioindigo dyes can be mentioned. These dyes may exhibit cyan only after a part of the chromophore is dissociated, and the counter cation in that case may be an alkali metal or an inorganic cation such as ammonium, pyridinium, It may be an organic cation such as a quaternary ammonium salt, and further may be a polymer cation having them in a partial structure.

In addition, water-soluble dyes such as direct dyes, acid dyes, food dyes, basic dyes, and reactive dyes can be used in combination. Among these, preferred is
CI Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207 , 211, 212, 214, 218, 21, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243, 247
CI Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, 101
CI Direct Yellow 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53, 58, 59, 68, 86, 87, 93, 95, 96, 98, 100 , 106, 108, 109, 110, 130, 132, 142, 144, 161, 163
CI Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80
84, 86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168, 189,
192, 193, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214, 218, 225, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289, 291
CI Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97, 108, 112, 113, 114, 117, 118, 121, 122, 125, 132 , 146, 154, 166, 168, 173, 199
CI Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127,
128, 131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299, 301, 305, 336, 337, 361, 396, 397
CI Acid Violet 5, 34, 43, 47, 48, 90, 103, 126
CI Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76, 79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195 , 196, 197, 199, 218, 219, 222, 227
CI Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112,
113, 120, 127: 1, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247, 258, 260, 264, 271, 277, 278, 279, 280, 288, 290, 326
CI Acid Black 7, 24, 29, 48, 52: 1, 172
CI Reactive Red 3, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40, 41, 43, 45, 49, 55
CI Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34
CI Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42
CI Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25, 26, 27, 28, 29, 38
CI Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32, 34
CI Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45, 46
CI Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37, 39, 40, 48
CI Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40
CI Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62, 65, 66, 69, 71
CI Basic Black 8, etc.

Furthermore, the present invention can also use an ink in which a pigment is used in combination with a dye.
As the pigment that can be used in the present invention, commercially available pigments and known pigments described in various documents can be used. Regarding the literature, the Color Index (Edited by The Society of Dyers and Colorists), “Revised New Handbook of Pigments” edited by the Japan Pigment Technology Association (published in 1989), “Latest Pigment Applied Technology” published by CMC (published in 1986), “Printing Ink Technology” CMC Publishing (1984), W. Herbst, K.M. Hunger co-authored, Industrial Organic Pigments (VCH Verlagsgesellschaft, published in 1993). Specifically, as organic pigments, azo pigments (azo lake pigments, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, indigo pigments, quinacridone Pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments), dyed lake pigments (acid or basic dye lake pigments), azine pigments, etc. C.I. of yellow pigment I. Pigment Yellow 34, 37, 42, 53, and other red pigments such as C.I. I. Pigment Red 101, 108, etc., blue pigments such as C.I. I. Pigment Blue 27, 29, 17: 1, etc., black pigments such as C.I. I. Pigment Black 7, magnetite, and other white pigments such as C.I. I. Pigment White 4, 6, 18, 21 and the like.

  As a pigment having a preferable color tone for image formation, a phthalocyanine pigment, an anthraquinone-based indanthrone pigment (for example, CI Pigment Blue 60), and a dyed lake pigment-based triarylcarbonium pigment are preferable for a blue or cyan pigment. Phthalocyanine pigments (preferred examples include copper phthalocyanine such as CI Pigment Blue 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, monochloro or low chlorinated copper) Among the phthalocyanines and alnium phthalocyanines, the pigments described in European Patent No. 860475, the metal-free phthalocyanine which is CI Pigment Blue 16, the phthalocyanines whose central metals are Zn, Ni and Ti, among them, CI pigment is preferable. Bl e 15: 3, 15: 4 and aluminum phthalocyanine) are most preferred.

  For red to purple pigments, azo pigments (preferred examples include CI Pigment Red 3, 5, 11, 22, 38, 48: 1, 48: 2, 48: 3, 48: 4, 49: 1, 52: 1, 53: 1, 57: 1, 63: 2, 144, 146, and 184). I. Pigment Red 57: 1, 146, 184), quinacridone pigments (preferred examples include CI Pigment Red 122, 192, 202, 207, 209, CI Pigment Violet 19, 42, particularly preferred are CI Pigment Red 122), dyed lake pigment-based triarylcarbonium pigments (preferred examples include xanthene-based CI Pigment Red 81: 1, CI Pigment Violet). 1, 2, 3, 27, 39), dioxazine pigments (for example, CI Pigment Violet 23, 37), diketopyrrolopyrrole pigments (for example, CI Pigment Red 254), perylene Pigments (e.g. CI Pi ment Violet 29), anthraquinone pigments (e.g., C.I. Pigment Violet 5: 1, the 31, the 33), thioindigo (e.g. C.I. Pigment Red 38, the 88) is preferably used.

  As yellow pigments, azo pigments (preferred examples include monoazo pigment-based CI Pigment Yellow 1, 3, 74, 98, disazo pigment-based CI Pigment Yellow 12, 13, 14, 16, 17, 83, synthetic azo-based CI Pigment Yellow 93, 94, 95, 128, 155, benzimidazolone-based CI Pigment Yellow 120, 151, 154, 156, 180, etc., among which benzidine is preferable. That are not used as raw materials), isoindoline / isoindolinone pigments (preferred examples include CI Pigment Yellow 109, 110, 137, and 139), and quinophthalone pigments (preferably examples include CI. .Pigm ent Yellow 138) and furapantron pigments (for example, CI Pigment Yellow 24) are preferably used.

Preferred examples of the black pigment include inorganic pigments (preferably carbon black and magnetite as examples) and aniline black.
In addition, an orange pigment (such as CI Pigment Orange 13, 16) or a green pigment (such as CI Pigment Green 7) may be used.

The pigment that can be used in the present invention may be the above-mentioned bare pigment or a surface-treated pigment. Surface treatment methods include resin or wax surface coating, surfactant deposition, reactive substances (eg radicals derived from silane coupling agents, epoxy compounds, polyisocyanates, diazonium salts, etc.) pigments A method of bonding to the surface is conceivable and is described in the following documents and patents.
(1) Properties and applications of metal soap (Sachishobo)
(2) Printing ink printing (CMC Publishing 1984)
(3) Latest pigment application technology (CMC Publishing 1986)
(4) U.S. Pat. Nos. 5,554,739 and 5,571,311 (5) JP-A Nos. 9-151342, 10-140065, 10-292143, and 11-166145 Self-dispersing pigments prepared by allowing a diazonium salt described in US Patent 4) to act on carbon black and encapsulated pigments prepared by the method described in Japanese Patent (5) above are used in inks. In particular, the dispersion stability can be obtained without using an extra dispersant.

In the present invention, the pigment may be further dispersed using a dispersant. Various known dispersants can be used in accordance with the pigment to be used, for example, a surfactant-type low-molecular dispersant or a polymer-type dispersant. Examples of the dispersant include those described in JP-A-3-69949, European Patent 549486 and the like. In addition, when a dispersant is used, a pigment derivative called a synergist may be added to promote adsorption of the dispersant to the pigment.
The particle size of the pigment that can be used in the present invention is preferably in the range of 0.01 to 10 μm after dispersion, and more preferably 0.05 to 1 μm.
As a method for dispersing the pigment, a known dispersion technique used in ink production or toner production can be used. Examples of the dispersing machine include vertical or horizontal agitator mills, attritors, colloid mills, ball mills, three roll mills, pearl mills, super mills, impellers, dispersers, KD mills, dynatrons, and pressure kneaders. Details are described in "Latest Pigment Application Technology" (CMC Publishing, 1986).

  Examples of water-soluble dyes used in the present invention include magenta dyes described in JP-A No. 2002-371214, phthalocyanine dyes described in JP-A No. 2002-309118, JP-A Nos. 2003-12952 and 2003-12956. It is also preferable to use the dyes described in water-soluble phthalocyanine dyes.

  The ink of the present invention contains a dye in a medium, preferably an aqueous medium. In the aqueous medium, water or a solvent such as a water-miscible organic solvent is added to water as necessary.

  The water-miscible organic solvent that can be used in the present invention is a material having functions such as an anti-drying agent, a penetration accelerator, and a wetting agent for ink jet recording inks in the field, and is mainly a high-boiling water-miscible material. An organic solvent is used. Such compounds include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyhydric alcohols (eg, , Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (eg, ethylene glycol monomethyl) Ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether Diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol Monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine) , Reethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2- Pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, the said water miscible organic solvent may use 2 or more types together.

Among these, alcohol solvents are particularly preferable. Further, the ink of the present invention preferably contains a water-miscible organic solvent having a boiling point of 150 ° C. or higher, and examples thereof include 2-pyrrolidone selected from the above.
These water-miscible organic solvents are preferably contained in the ink in a total amount of 5 to 60% by mass, particularly preferably 10 to 45% by mass.

By including a surfactant in the ink of the present invention and adjusting the liquid physical properties of the ink, the ink ejection stability is improved, and the water resistance of the image is improved and the printed ink is prevented from bleeding. Can be given.
Examples of the surfactant include anionic surfactants such as sodium dodecyl sulfate, sodium dodecyloxysulfonate, sodium alkylbenzene sulfonate, and cationic surfactants such as cetylpyridinium chloride, trimethylcetylammonium chloride, tetrabutylammonium chloride, And nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene naphthyl ether, polyoxyethylene octylphenyl ether, and the like. Among these, nonionic surfactants are particularly preferably used.

  The content of the surfactant is 0.001 to 20% by mass, preferably 0.005 to 10% by mass, and more preferably 0.01 to 5% by mass with respect to the ink.

When the dye is an oil-soluble dye, the ink of the present invention can be prepared by emulsifying and dispersing an ink stock solution in which the oil-soluble dye is dissolved in a high-boiling organic solvent in an aqueous medium.
The boiling point of the high-boiling organic solvent used in the present invention is 150 ° C. or higher, preferably 170 ° C. or higher.
For example, phthalic acid esters (for example, dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decyl phthalate, bis (2,4-di-tert-amylphenyl) isophthalate, bis (1, 1-diethylpropyl) phthalate), esters of phosphoric acid or phosphones (eg diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl diphenyl phosphate, dioctyl butyl phosphate, tricyclohexyl phosphate, tri-2-ethylhexyl phosphate , Tridodecyl phosphate, di-2-ethylhexylphenyl phosphate), benzoic acid esters (eg 2-ethylhexyl benzoate, 2,4-dicarbonate) Lobenzoate, dodecylbenzoate, 2-ethylhexyl-p-hydroxybenzoate), amides (eg, N, N-diethyldodecanamide, N, N-diethyllaurylamide), alcohols or phenols (isostearyl alcohol, 2, 4-di-tert-amylphenol), aliphatic esters (eg, dibutoxyethyl succinate, di-2-ethylhexyl succinate, 2-hexyldecyl tetradecanoate, tributyl citrate, diethyl azelate, isostearyl lactate , Trioctyl citrate), aniline derivatives (N, N-dibutyl-2-butoxy-5-tert-octylaniline, etc.), chlorinated paraffins (paraffins having a chlorine content of 10% to 80%), trimesic acid esters Kind (for example, Tributyl trimesate), dodecylbenzene, diisopropylnaphthalene, phenols (eg, 2,4-di-tert-amylphenol, 4-dodecyloxyphenol, 4-dodecyloxycarbonylphenol, 4- (4-dodecyloxyphenylsulfonyl)) Phenol), carboxylic acids (eg, 2- (2,4-di-tert-amylphenoxybutyric acid, 2-ethoxyoctanedecanoic acid), alkylphosphoric acids (eg, di-2 (ethylhexyl) phosphoric acid, diphenylphosphoric acid) The high-boiling organic solvent can be used in an amount of 0.01 to 3 times, preferably 0.01 to 1.0 times the mass ratio of the oil-soluble dye.
These high-boiling organic solvents may be used alone or in a mixture of several types (eg tricresyl phosphate and dibutyl phthalate, trioctyl phosphate and di (2-ethylhexyl) sebacate, dibutyl phthalate and poly (Nt-butyl). Acrylamide)].

Examples of other high boiling point organic solvents used in the present invention and / or methods for synthesizing these high boiling point organic solvents are disclosed in, for example, US Pat. Nos. 2,322,027, 2,533,514, and 2 772,163, 2,835,579, 3,594,171, 3,676,137, 3,689,271, 3,700,454 3,748,141, 3,764,336, 3,765,897, 3,912,515, 3,936,303, 4, No. 004,928, No. 4,080,209, No. 4,127,413, No. 4,193,802, No. 4,207,393, No. 4,220,711, No. 4,239,851, No. 4,278,757, No. 4 353,979, 4,363,873, 4,430,421, 4,430,422, 4,464,464, 4,483,918, 4,540,657, 4,684,606, 4,728,599, 4,745,049, 4,935,321, 5,013 , 639, European Patent Nos. 276,319A, 286,253A, 289,820A, 309,158A, 309,159A, 309,160A, 509 No. 311A, No. 510,576A, East German Patent No. 147,009, No. 157,147, No. 159,573, No. 225,240A, British Patent No. 2,091,124A, JP-A-48-47335, 50 No. 26530, No. 51-25133, No. 51-26036, No. 51-27921, No. 51-27922, No. 51-149028, No. 52-46816, No. 53-1520, No. 53-1521 53-15127, 53-146622, 54-91325, 54-106228, 54-118246, 55-59464, 56-64333, 56-81836, 59-204041, 61-84641, 62-118345, 62-247364, 63-167357, 63-214744, 63-301941, 63-94552, 64-945 9454, 64-68745, JP-A-1-101543, 1-102454, 2-792, and 2 No.-4239, No. 2-43541, No. 4-29237, No. 4-30165, No. 4-232946, No. 4-346338 and the like.
The high boiling point organic solvent is used in an amount of 0.01 to 3.0 times, preferably 0.01 to 1.0 times the mass ratio of the oil-soluble dye.

  In the present invention, the oil-soluble dye and the high boiling point organic solvent are preferably emulsified and dispersed in an aqueous medium. In the emulsification dispersion, a low boiling organic solvent can be used depending on the case from the viewpoint of emulsification. The low boiling point organic solvent is an organic solvent having a boiling point of about 30 ° C. or higher and 150 ° C. or lower at normal pressure. For example, esters (eg ethyl acetate, butyl acetate, ethyl propionate, β-ethoxyethyl acetate, methyl cellosolve acetate), alcohols (eg isopropyl alcohol, n-butyl alcohol, secondary butyl alcohol), ketones (eg methyl isobutyl) Ketones, methyl ethyl ketone, cyclohexanone), amides (for example, dimethylformamide, N-methylpyrrolidone), ethers (for example, tetrahydrofuran, dioxane) and the like are preferably used, but are not limited thereto.

Emulsification dispersion is to disperse an oil phase in which a dye is dissolved in a mixed solvent of a high-boiling organic solvent and, optionally, a low-boiling organic solvent, in an aqueous phase mainly composed of water, to form fine oil droplets in the oil phase. (This oil layer may be used as an ink stock solution, or the oil layer dispersed in the water phase may be used as an ink stock solution). At this time, components such as a surfactant, a wetting agent, a dye stabilizer, an emulsion stabilizer, a preservative, and an antifungal agent can be added to either or both of the aqueous phase and the oil phase as necessary. .
As an emulsification method, a method of adding an oil phase to an aqueous phase is common, but a so-called phase inversion emulsification method in which an aqueous phase is dropped into an oil phase can also be preferably used. The emulsification method can also be applied when the dye is water-soluble and the component is oil-soluble.

  When emulsifying and dispersing, various surfactants can be used. Anionic interfaces such as fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfates, etc. Activator, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethyleneoxypropylene block copolymer Nonionic surfactants such as Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred. Further, pages (37) to (38) of JP-A-59-157,636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

For the purpose of stabilization immediately after emulsification, a water-soluble polymer can be added in combination with the surfactant. As the water-soluble polymer, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic acid, polyacrylamide or a copolymer thereof is preferably used. It is also preferable to use natural water-soluble polymers such as polysaccharides, casein, and gelatin. Further, for stabilization of the dye dispersion, acrylic acid esters, methacrylic acid esters, vinyl esters, acrylamides, methacrylamides, olefins, styrenes, vinyl ethers that are not substantially soluble in an aqueous medium, Polyvinyl, polyurethane, polyester, polyamide, polyurea, polycarbonate and the like obtained by polymerization of acrylonitrile can also be used in combination. These polymers preferably contain —SO ₃ ⁻ and —COO ⁻ . When these polymers that do not substantially dissolve in an aqueous medium are used in combination, it is preferably used in an amount of 20% by mass or less, more preferably 10% by mass or less of the high boiling point organic solvent.

When an oil-soluble dye or a high-boiling organic solvent is dispersed by emulsification to obtain a water-based ink, control of the particle size is particularly important. In order to increase color purity and density when an image is formed by inkjet, it is essential to reduce the average particle size. The volume average particle size is preferably 1 μm or less, more preferably 5 to 100 nm.
In addition to static light scattering, dynamic light scattering, and centrifugal sedimentation, the methods for measuring the volume average particle size and particle size distribution of the dispersed particles are described in pages 417 to 418 of Experimental Chemistry Course 4th edition. It can be easily measured by a known method such as using a method. For example, after dilution with distilled water so that the particle concentration in the ink is 0.1 to 1% by mass, it is easy with a commercially available volume average particle size measuring device (for example, Microtrac UPA (manufactured by Nikkiso Co., Ltd.)). Can be measured. Furthermore, the dynamic light scattering method using the laser Doppler effect is particularly preferable because it can measure the particle size up to a small size.
The volume average particle diameter is an average particle diameter weighted by the particle volume, and is the sum of the diameter of each particle multiplied by the volume of the particle divided by the total volume of the particles. The volume average particle diameter is described on page 119 of “Chemistry of Polymer Latex (by Soichi Muroi, Polymer Press Society)”.

It was also found that the presence of coarse particles also plays a very important role in printing performance. That is, it has been found that the coarse particles clog the nozzles of the head, or even if they are not clogged, the ink is not ejected or the ink is not ejected, resulting in a serious influence on the printing performance. In order to prevent this, it is important to limit the number of particles of 5 μm or more to 10 or less and 1 μm or more to 1000 or less in 1 μl of ink.
As a method for removing these coarse particles, a known centrifugal separation method, microfiltration method, or the like can be used. These separation means may be performed immediately after the emulsification dispersion, or may be performed immediately after filling the ink dispersion after adding various components such as a wetting agent and a surfactant to the emulsification dispersion.
A mechanical emulsifier can be used as an effective means for reducing the average particle size and eliminating coarse particles.

As the emulsifying device, known devices such as a simple stirrer, impeller stirring method, in-line stirring method, mill method such as colloid mill, and ultrasonic method can be used, but the use of a high-pressure homogenizer is particularly preferable.
The high-pressure homogenizer is described in detail in US Pat. No. 4,533,254, JP-A-6-47264, and the like. MICROFLUIDEX INC.), Optimizer (Sugino Machine Co., Ltd.) and the like.
In addition, a high-pressure homogenizer equipped with a mechanism for atomizing in an ultrahigh-pressure jet stream as described in US Pat. No. 5,720,551 in recent years is particularly effective for the emulsification dispersion of the present invention. An example of an emulsifying apparatus using this ultra-high pressure jet flow is DeBEE2000 (BEE INTERNIONAL LTD.).

The pressure when emulsifying with the high-pressure emulsifying dispersion device is 50 MPa or more, preferably 60 MPa or more, more preferably 180 MPa or more.
For example, it is a particularly preferable method that two or more types of emulsifiers are used in combination by a method such as emulsification with a stirring emulsifier and then passing through a high-pressure homogenizer. Also preferred is a method of once emulsifying and dispersing with these emulsifying devices, adding components such as a wetting agent and a surfactant, and then allowing the cartridge to pass through a high-pressure homogenizer again while filling the ink.
When a low boiling point organic solvent is contained in addition to the high boiling point organic solvent, it is preferable to remove the low boiling point solvent from the viewpoint of the stability of the emulsion and safety and health. Various known methods can be used as the method for removing the low boiling point solvent depending on the type of the solvent. That is, an evaporation method, a vacuum evaporation method, an ultrafiltration method, and the like. This step of removing the low-boiling organic solvent is preferably performed as soon as possible immediately after emulsification.

  Ink jet ink preparation methods are described in detail in JP-A Nos. 5-148436, 5-295212, 7-97541, 7-82515, and 7-118584. Thus, it can also be used for preparing the ink of the present invention.

  The ink of the present invention can contain a functional component for imparting various functions to the ink. For example, as the functional component, the above-mentioned various solvents, a drying preventive agent for preventing clogging due to dry operation at the ink ejection port, a penetration enhancer for allowing the ink to permeate the paper better, an ultraviolet absorber, Antioxidants, viscosity modifiers, surface tension modifiers, dispersants, dispersion stabilizers, antifungal agents, rust inhibitors, pH adjusters, antifoaming agents, chelating agents, and the like can be mentioned. Can be appropriately selected and used. These functional components include a single compound that can exhibit one or more functions. Therefore, in the following blending ratio of the functional component, the handling of the functional component in the case where the function is duplicated shall include the compound in each functional component independently.

  The drying inhibitor used in the present invention is preferably a water-soluble organic solvent having a vapor pressure lower than that of water. Specific examples include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, glycerin. Polyhydric alcohols typified by trimethylolpropane, etc., lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, dimethyl sulfoxide, 3 Sulfur-containing compounds such as sulfolane, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are more preferred. Moreover, said drying inhibitor may be used independently and may be used together 2 or more types. These drying inhibitors are preferably contained in the ink in an amount of 10 to 50% by mass.

  Examples of penetration enhancers used in the present invention include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic surfactants. Etc. can be used. If these are contained in the ink in an amount of 10 to 30% by mass, the effect is sufficient, and it is preferable to use them in a range of addition amounts that do not cause printing bleeding and paper loss (print through).

  Examples of the ultraviolet absorber used for improving the storability of the image in the present invention include JP-A Nos. 58-185677, 61-190537, JP-A-2-782, and JP-A-5-97075. Benzotriazole compounds described in JP-A-9-34057, etc., benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194443, US Pat. No. 3,214,463, etc. 48-30492, 56-21114, and cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, and 8-239368. And triazine compounds described in JP-A-10-182621, JP-A-8-501291, etc. Jar No. Compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based compounds and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.

  In the present invention, various organic and metal complex anti-fading agents can be used as the antioxidant used to improve image storage stability. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of the representative compounds described in pages 127 to 137 of JP-A-62-215272 can be used.

  Examples of the rust inhibitor used in the present invention include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole. These are preferably used in the ink in an amount of 0.02 to 5.00% by mass.

The conductivity of the ink of the present invention is in the range of 0.01 to 10 S / m. Among these, a preferable range is a conductivity of 0.05 to 5 S / m.
The conductivity can be measured by an electrode method using commercially available saturated potassium chloride.
The conductivity can be controlled mainly by the ion concentration in the aqueous solution. When the salt concentration is high, desalting can be performed using an ultrafiltration membrane or the like. Moreover, when adjusting conductivity by adding salt etc., it can adjust by adding various organic substance salt and inorganic substance salt.
Inorganic salts include potassium halide, sodium halide, sodium sulfate, potassium sulfate, sodium hydrogen sulfate, potassium hydrogen sulfate, sodium nitrate, potassium nitrate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium phosphate, sodium monohydrogen phosphate, Inorganic compounds such as boric acid, potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium acetate, potassium acetate, potassium tartrate, sodium tartrate, sodium benzoate, potassium benzoate, sodium p-toluenesulfonate, potassium saccharinate Organic compounds such as potassium phthalate and sodium picolinate can also be used.
The conductivity can also be adjusted by selecting the components of the aqueous medium described later.

The viscosity of the ink of the present invention is preferably 1 to 30 mPa · s at 25 ° C. More preferably, it is 2-15 mPa * s, Most preferably, it is 2-10 mPa * s. If it exceeds 30 mPa · s, the fixing speed of the recorded image becomes slow, and the discharge performance also deteriorates. If it is less than 1 mPa · s, the recorded image is blurred and the quality is lowered.
The viscosity can be arbitrarily adjusted by adding the ink solvent. Examples of the ink solvent include glycerin, diethylene glycol, triethanolamine, 2-pyrrolidone, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether.
A viscosity modifier may be used. Examples of the viscosity modifier include water-soluble polymers such as celluloses and polyvinyl alcohol, and nonionic surfactants. In more detail, “Viscosity Preparation Technology” (Technical Information Association, 1999), Chapter 9, and “Chemicals for Inkjet Printers (98 Supplement)-Material Development Trends and Prospects Survey” (CMC, 1997) 162- Page 174.

  The method for measuring the viscosity of the liquid is described in detail in JIS Z8803, but can be easily measured with a commercially available viscometer. For example, the rotary type includes Tokyo Keiki B-type viscometer and E-type viscometer. In this invention, it measured at 25 degreeC by the vibration type VM-100AL type of Yamaichi Electric. The unit of viscosity is Pascal second (Pa · s), but millipascal second (mPa · s) is usually used.

The surface tension of the ink used in the present invention is preferably 20 to 50 mN / m, more preferably 20 to 40 mN / m at 25 ° C. for both dynamic and static surface tension. If the surface tension exceeds 50 mN / m, the ejection quality, bleeding at the time of color mixing, print quality such as whiskers, etc. will be significantly reduced. If the surface tension of the ink is 20 mN / m or less, there may be a printing failure due to ink adhesion to the hard surface during ejection.
For the purpose of adjusting the surface tension, various cations, anions, nonionic surfactants and betaine surfactants can be added. Moreover, 2 or more types of surfactant can be used together.

As a static surface tension measuring method, a capillary rising method, a dropping method, a hanging ring method and the like are known. In the present invention, a vertical plate method is used as a static surface tension measuring method.
When a thin plate of glass or platinum is partially immersed in the liquid and suspended vertically, the surface tension of the liquid acts downward along the length of contact between the liquid and the plate. The surface tension can be measured by balancing this force with an upward force.

  Examples of the dynamic surface tension measurement method include “New Experimental Chemistry Course, Vol. 18, Interface and Colloid” [Maruzen Co., Ltd., p. 69-90 (1977)], the vibration jet method, the meniscus dropping method, the maximum bubble pressure method and the like are known, and further, the liquid film breakage as described in JP-A-3-2064 is known. In the present invention, a bubble pressure differential pressure method is used as a dynamic surface tension measurement method. The measurement principle and method will be described below.

  When bubbles are generated in the solution that has become homogeneous by stirring, a new gas-liquid interface is generated, and the surfactant molecules in the solution gather on the surface of the water at a constant rate. When the bubble rate (bubble generation rate) is changed, if the generation rate slows down, more surfactant molecules gather on the surface of the bubble, so the maximum bubble pressure just before the bubble pops is reduced, The maximum bubble pressure (surface tension) relative to the bubble rate can be detected. As a preferable dynamic surface tension measurement, a method is used in which bubbles are generated in a solution using two large and small probes, the differential pressure in the maximum bubble pressure state of the two probes is measured, and the dynamic surface tension is calculated. Can be mentioned.

The non-volatile component in the ink of the present invention is 10 to 70% by mass of the total amount of the ink. Ink ejection stability, print image quality, various image robustness, image bleeding after printing, and stickiness of the printing surface In terms of reduction, it is preferably 20 to 60% by mass, and more preferably in terms of ink ejection stability and reduction of image bleeding after printing.
Here, the non-volatile component means a liquid, a solid component or a high molecular weight component having a boiling point of 150 ° C. or higher under 1 atm. Non-volatile components of ink-jet ink are dyes, high boiling point solvents, polymer latex added as necessary, surfactants, dye stabilizers, antifungal agents, buffering agents, etc., and many of these non-volatile components are Other than the dye stabilizer, the dispersion stability of the ink is lowered, and it remains on the inkjet image-receiving paper even after printing. It has the property of exacerbating image bleeding under conditions.

  In the present invention, a high molecular weight compound can also be contained. Here, the high molecular weight compound means all high molecular compounds having a number average molecular weight of 5000 or more contained in the ink. These polymer compounds are soluble in water-soluble polymer compounds that are substantially soluble in aqueous media, water-dispersible polymer compounds such as polymer latex and polymer emulsion, and polyhydric alcohols that are used as auxiliary solvents. Alcohol-soluble polymer compounds and the like can be mentioned, and any compound that can be dissolved or dispersed substantially uniformly in the ink liquid is included in the polymer compound of the present invention.

Specific examples of the water-soluble polymer compound include polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyethylene oxide, water-soluble polymers such as polyoxyalkylene oxide such as polypropylene oxide, polysaccharides, starch, cationized starch, casein, natural water-soluble polymers such as gelatin, polyacrylic acid, polyacrylamide or aqueous acrylic resins such as a copolymer thereof, aqueous alkyd resins, -SO in the molecule ₃ ^-, Examples thereof include water-soluble polymer compounds having a —COO 2 ^— group and substantially soluble in an aqueous medium.
Examples of the polymer latex include styrene-butadiene latex, styrene-acrylic latex, and polyurethane latex. Furthermore, an acrylic emulsion etc. are mentioned as a polymer emulsion.
These water-soluble polymer compounds can be used alone or in combination of two or more.

As described above, the water-soluble polymer compound is used as a viscosity modifier to adjust the viscosity of the ink in a viscosity region having good ejection characteristics. However, if the amount of the water-soluble polymer compound added is large, the viscosity of the ink increases. As a result, the ejection stability of the ink liquid is lowered, and the nozzle is easily clogged by the precipitate when the ink is aged.
The addition amount of the polymer compound of the viscosity modifier depends on the molecular weight of the compound to be added (the higher the molecular weight, the smaller the addition amount may be), but the addition amount is 0 to 5% by mass, preferably the total amount of the ink Is 0 to 3% by mass, more preferably 0 to 1% by mass.

  Further, in the present invention, the above-mentioned cation, anion, nonionic and betaine surfactants are necessary as a dispersant and dispersion stabilizer, and fluorine-based, silicone-based compounds and chelating agents represented by EDTA are required as an antifoaming agent. Can be used according to.

The reflection type medium that is a printing medium preferably used in the present invention will be further described. Examples of reflective media include recording paper and recording film. The support in recording paper and recording film is made of chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, CGP, and waste paper pulp such as DIP. Additives such as known pigments, binders, sizing agents, fixing agents, cationic agents, paper strength enhancers, etc. can be mixed and manufactured using various devices such as long net paper machines and circular net paper machines. is there. As the support, in addition to these supports, either synthetic paper or plastic film sheet may be used. The thickness of the support is preferably 10 to 250 μm and the basis weight is preferably 10 to 250 g / m 2.
An image receiving layer and a back coat layer may be provided on the support as they are, and the image receiving material of the ink and ink set of the present invention may be used. A layer may be provided as an image receiving material. Further, the support may be flattened by a calendar device such as a machine calendar, a TG calendar, or a soft calendar.
As the support, paper and plastic film laminated on both sides with polyolefin (eg, polyethylene, polystyrene, polybutene and their copolymers) or polyethylene terephthalate are more preferably used. It is preferable to add a white pigment (eg, titanium oxide, zinc oxide) or a tinting dye (eg, cobalt blue, ultramarine blue, neodymium oxide) to the polyolefin.

  The image receiving layer provided on the support contains a porous material and an aqueous binder. The image receiving layer preferably contains a pigment, and the pigment is preferably a white pigment. White pigments include calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, barium sulfate, calcium sulfate, titanium dioxide, Examples thereof include inorganic white pigments such as zinc sulfide and zinc carbonate, organic pigments such as styrene pigments, acrylic pigments, urea resins and melamine resins. A porous white inorganic pigment is particularly preferable, and synthetic amorphous silica having a large pore area is particularly preferable. As the synthetic amorphous silica, either anhydrous silicic acid obtained by a dry production method (gas phase method) or hydrous silicic acid obtained by a wet production method can be used.

  Specific examples of the recording paper containing the pigment in the image receiving layer include JP-A Nos. 10-81064, 10-119423, 10-157277, 10-217601, 11-348409, and JP-A-2001-138621. 2000-43401, 2000-2111235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, 8-9. 2093, 8-174992, 11-192777, JP-A-2001-301314, and the like can be used.

  The aqueous binder contained in the image receiving layer includes water-soluble polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyalkylene oxide, polyalkylene oxide derivatives, etc. Examples thereof include water-dispersible polymers such as polymers, styrene butadiene latexes, and acrylic emulsions. These aqueous binders can be used alone or in combination of two or more. In the present invention, among these, polyvinyl alcohol and silanol-modified polyvinyl alcohol are particularly preferable in terms of adhesion to the pigment and resistance to peeling of the ink receiving layer.

  The image receiving layer can contain a mordant, a water resistance agent, a light resistance improver, a gas resistance improver, a surfactant, a hardener and other additives in addition to the pigment and the aqueous binder.

The mordant added to the image receiving layer is preferably immobilized. For that purpose, a polymer mordant is preferably used.
For the polymer mordant, JP-A-48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, 60-23835, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122294, 60- No. 235134, Japanese Patent Application Laid-Open No. 1-161236, U.S. Pat. It is described in each specification of the same 4450224. An image receiving material containing a polymer mordant described in JP-A-1-161236, pages 212 to 215 is particularly preferred. When the polymer mordant described in the publication is used, an image with excellent image quality is obtained and the light resistance of the image is improved.

  The water-proofing agent is effective for making the image water-resistant. As these water-proofing agents, cationic resins are particularly desirable. Examples of such a cationic resin include polyamide polyamine epichlorohydrin, polyethyleneimine, polyamine sulfone, dimethyldiallylammonium chloride polymer, and cationic polyacrylamide. The content of these cationic resins is preferably 1 to 15% by mass, particularly 3 to 10% by mass, based on the total solid content of the ink receiving layer.

Examples of the light resistance improver and gas resistance improver include phenol compounds, hindered phenol compounds, thioether compounds, thiourea compounds, thiocyanate compounds, amine compounds, hindered amine compounds, TEMPO compounds, hydrazine compounds, hydrazide compounds, amidine compounds, Vinyl group-containing compounds, ester compounds, amide compounds, ether compounds, alcohol compounds, sulfinic acid compounds, saccharides, water-soluble reducing compounds, organic acids, inorganic acids, hydroxy group-containing organic acids, benzotriazole compounds, benzophenone compounds, triazine compounds , Heterocyclic compounds, water-soluble metal salts, organometallic compounds, metal complexes, and the like.
Specific examples of these compounds include JP-A-10-182621, JP-A-2001-260519, JP-A-2000-260519, JP-B-4-34953, JP-B-4-34513, and JP-B-4-34512. , JP-A-11-170686, JP-A-60-67190, JP-A-7-276808, JP-A-2000-94829, JP-T 8-512258, JP-A-11-321090, etc. Can be given.

The surfactant functions as a coating aid, a peelability improver, a slippage improver or an antistatic agent. The surfactant is described in JP-A Nos. 62-173463 and 62-183457.
An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include a fluorine-based surfactant, an oily fluorine-based compound (eg, fluorine oil), and a solid fluorine compound resin (eg, tetrafluoroethylene resin). The organic fluoro compounds are described in JP-B-57-9053 (columns 8 to 17), JP-A-61-20994, and 62-135826.

  As the hardener, materials described in JP-A-1-161236, page 222, JP-A-9-263036, JP-A-10-119423, and JP-A-2001-310547 can be used.

  Examples of other additives to be added to the image receiving layer include pigment dispersants, thickeners, antifoaming agents, dyes, fluorescent whitening agents, preservatives, pH adjusters, and matting agents. The ink receiving layer may be one layer or two layers.

The recording paper and the recording film can be provided with a back coat layer, and examples of components that can be added to this layer include a white pigment, an aqueous binder, and other components.
Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. , Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene And organic pigments such as polyethylene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

  As the aqueous binder contained in the backcoat layer, styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose Water-soluble polymers such as hydroxyethyl cellulose and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion. Examples of other components contained in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

  A polymer fine particle dispersion may be added to the constituent layers (including the back layer) of the inkjet recording paper and recording film. The polymer fine particle dispersion is used for the purpose of improving the physical properties of the film such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer fine particle dispersion is described in JP-A Nos. 62-245258, 62-136648, and 62-110066. When a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to a layer containing a mordant, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

  The ink of the present invention can also be used for purposes other than inkjet recording. For example, it can be used for display image materials, image forming materials for interior decoration materials, and image forming materials for outdoor decoration materials.

  Display image materials include posters, wallpaper, small decorative items (such as figurines and dolls), commercial flyers, wrapping paper, wrapping materials, paper bags, plastic bags, packaging materials, signs, transportation (automobiles, buses, trains, etc.) ) Refers to various things such as images drawn and attached to the side, clothes with logos, and so on. When the dye of the present invention is used as a material for forming a display image, the image includes all patterns of dyes that can be recognized by humans, such as abstract designs, characters, and geometric patterns, in addition to images in a narrow sense.

  The interior decoration material refers to various items such as wallpaper, decorative accessories (such as figurines and dolls), lighting fixture members, furniture members, floor and ceiling design members. When the dye of the present invention is used as an image forming material, the image includes all patterns of dyes that can be recognized by humans such as abstract designs, characters, and geometric patterns in addition to images in a narrow sense.

  The outdoor decoration material refers to various materials such as wall materials, roofing materials, signboards, gardening materials, outdoor decoration accessories (such as figurines and dolls), and members of outdoor lighting equipment. When the dye of the present invention is used as an image forming material, the image includes not only images in a narrow sense but also all patterns of dyes that can be recognized by humans, such as abstract designs, characters, and geometric patterns.

  In the above applications, examples of media on which a pattern is formed include various materials such as paper, fiber, cloth (including non-woven fabric), plastic, metal, and ceramics. As the dyeing form, the dye can be fixed in the form of mordanting, printing, or a reactive dye having a reactive group introduced. Among these, it is preferable that the mordanting is performed.

In the production of an ink stock solution or ink, ultrasonic vibration can also be applied to the dissolution process of additives such as dyes.
In order to prevent bubbles from being generated by the pressure applied by the recording head, ultrasonic vibration means that bubbles are generated by applying ultrasonic energy equal to or higher than the energy received by the recording head in advance during the ink manufacturing process. Is to be removed.
The ultrasonic vibration is usually an ultrasonic wave having a frequency of 20 kHz or higher, preferably 40 kHz or higher, more preferably 50 kHz. The energy applied to the liquid by ultrasonic vibration is usually 2 × 10 ⁷ J / m ³ or more, preferably 5 × 10 ⁷ J / m ³ or more, more preferably 1 × 10 ⁸ J / m ³ or more. . Further, the application time of ultrasonic vibration is usually about 10 minutes to 1 hour.
The step of applying ultrasonic vibration shows an effect at any time after the dye is put into the medium. The effect is exhibited even if ultrasonic vibration is applied after the completed ink is once stored. However, adding ultrasonic vibration when the dye is dissolved and / or dispersed in the medium has a greater effect of removing bubbles, and the ultrasonic vibration promotes dissolution and / or dispersion of the dye in the medium. This is preferable.
That is, the step of applying at least ultrasonic vibration can be performed in any case, either during or after the step of dissolving and / or dispersing the dye in the medium. In other words, the step of applying at least the ultrasonic vibration can be arbitrarily performed once or more after the ink preparation until it becomes a product.
As an embodiment, the step of dissolving and / or dispersing in the medium preferably includes a step of dissolving the dye in a medium of a part of the whole medium and a step of mixing the remaining medium, and at least one of the above It is preferable to apply ultrasonic vibration to this step, and it is more preferable to apply at least ultrasonic vibration to the step of dissolving the dye in a part of the medium.
The step of mixing the remaining solvent may be a single step or a plurality of steps.
In addition, it is preferable to use heat degassing or vacuum degassing in combination with the ink production according to the present invention because the effect of removing bubbles in the ink is improved. The heat degassing step or the vacuum degassing step is preferably performed simultaneously with or after the step of mixing the remaining medium.
Examples of the ultrasonic vibration generating means in the step of applying ultrasonic vibration include known devices such as an ultrasonic disperser.

When producing the ink stock solution or ink of the present invention, a step of removing dust that is a solid content by filtration, which is performed after further preparation of the liquid, is important. A filtration filter is used for this work. The filtration filter at this time is a filter having an effective diameter of 1 μm or less, preferably 0.3 μm or less and 0.05 μm or more, particularly preferably 0.3 μm or less and 0.25 μm or more. Use. Various materials can be used as the filter material, but in the case of water-soluble dye inks, it is preferable to use a filter prepared for an aqueous solvent. Among them, it is particularly preferable to use a filter made of a polymer material that hardly generates dust. As the filtration method, the solution may be passed through a solution, and either pressure filtration or vacuum filtration can be used.
After this filtration, air is often taken into the solution. Since bubbles caused by air often cause image disturbance in ink jet recording, it is preferable to separately provide the aforementioned defoaming step. As the defoaming method, the filtered solution may be allowed to stand, or various methods such as ultrasonic defoaming and vacuum defoaming using a commercially available apparatus can be used. In the case of defoaming with ultrasonic waves, the defoaming operation is preferably performed for about 30 seconds to 2 hours, more preferably about 5 minutes to 1 hour.
These operations are preferably performed using a space such as a clean room or a clean bench in order to prevent dust from entering during the operation. In the present invention, it is particularly preferable to perform this operation in a space of class 1000 or less as the degree of cleanliness. Here, “cleanness” refers to a value measured by a dust counter.

  In the present invention, the ink droplet volume on the recording material is from 0.1 pl to 100 pl. A preferable range of the droplet ejection volume is 0.5 pl or more and 50 pl or less, and a particularly preferable range is 2 pl or more and 50 pl or less.

In the present invention, there is no limitation on the ink jet recording method as long as the image recording is performed by the ink jet printer using the ink or ink set of the present invention, and a known method such as electrostatic attraction is used. Charge control method that ejects ink, drop-on-demand method (pressure pulse method) that uses vibration pressure of piezo elements, acoustic ink jet that ejects ink using radiation pressure by irradiating the ink with an electrical signal converted into an acoustic beam It is used for a method and a thermal ink jet (bubble jet) method in which bubbles are formed by heating ink and using the generated pressure.
Inkjet recording methods use a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method is included. The ink droplet volume is controlled mainly by the print head.

For example, in the case of the thermal ink jet method, the droplet ejection volume can be controlled by the structure of the print head. That is, droplets can be ejected in a desired size by changing the sizes of the ink chamber, the heating unit, and the nozzle. Even in the case of the thermal ink jet method, it is possible to realize droplet ejection of a plurality of sizes by providing a plurality of print heads having different heating parts and nozzle sizes.
In the case of the drop-on-demand method using a piezo element, the droplet ejection volume can be changed due to the structure of the print head as in the thermal ink jet method, but the waveform of the drive signal that drives the piezo element is controlled as described later. By doing so, droplets of a plurality of sizes can be ejected with a print head having the same structure.

The ejection frequency when the ink of the present invention is ejected onto a recording material is preferably 1 KHz or more.
In order to record a high-quality image such as a photograph, it is necessary to set the droplet ejection density to 600 dpi (number of dots per inch) or more in order to reproduce a sharp image with small ink droplets.
On the other hand, when ink is ejected by a head having a plurality of nozzles, the number of heads that can be driven simultaneously is about several tens to 200 in the type in which the recording paper and the head move in a direction orthogonal to each other, There is a restriction that there are several hundreds even if the head is called a fixed type. This is because there are restrictions on driving power, and heat generated by the head affects the image, so that a large number of head nozzles cannot be driven simultaneously.
Here, the recording speed can be increased by increasing the drive frequency.
In the case of the thermal ink jet method, the droplet ejection frequency can be controlled by controlling the frequency of the head drive signal for heating the head.
In the case of the piezo method, this is possible by controlling the frequency of a signal for driving the piezo.
The driving of the piezo head will be described. For the image signal to be printed, the droplet size, droplet ejection speed, and droplet ejection frequency are determined by the printer control unit, and a signal for driving the print head is created. The drive signal is supplied to the print head. The droplet ejection size, droplet ejection speed, and droplet ejection frequency are controlled by a signal for driving the piezo. Here, the droplet ejection size and droplet ejection speed are determined by the shape and amplitude of the drive waveform, and the frequency is determined by the signal repetition period.
When this droplet ejection frequency is set to 10 kHz, the head is driven every 100 microseconds, and recording of one line is completed in 400 microseconds. By setting the moving speed of the recording paper to move 1/600 inch in 400 microseconds, that is, approximately 42 microns, it is possible to print at a speed of one sheet in 1.2 seconds.

With regard to the configuration of the printing apparatus and the printer used in the present invention, for example, a mode as disclosed in JP-A-11-170527 is preferable. For the ink cartridge, for example, the one disclosed in Japanese Patent Laid-Open No. 5-229133 is suitable. With respect to the suction and the configuration of a cap or the like that covers the print head at that time, for example, the one disclosed in JP-A-7-276671 is suitable. Further, it is preferable that a filter for eliminating bubbles as disclosed in JP-A-9-277552 is provided in the vicinity of the head.
The surface of the nozzle is preferably subjected to water repellent treatment as described in JP-A-2002-292878. The application may be a printer connected to a computer or an apparatus specialized for printing photographs.
In the ink jet recording method applied to the present invention, it is preferable that the average droplet ejection speed when ejecting ink onto a recording material is 2 m / sec or more, preferably 5 m / sec or more.
The droplet ejection speed is controlled by controlling the shape and amplitude of the waveform that drives the head.
In addition, by using a plurality of drive waveforms properly, it is possible to eject droplets of a plurality of sizes with the same head.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this. The dyes used in the following examples are shown below.

Example 1
(Preparation of ink stock solution)
850 g of deionized water was added to 150 g of a black dye of compound A [oxidation potential: 1.31 V (vs SCE)] and stirred for 1 hour while heating at 60 to 65 ° C. After the dye was completely dissolved, it was cooled to room temperature, and 1.0 g of a preservative PROXEL XL2 (Avecia) was added. After stirring for 10 minutes, a liquid having a pH changed using 1 mol / l hydrochloric acid or potassium hydroxide was prepared, and filtered under reduced pressure with a microfilter having an average pore diameter of 0.2 μm, so that the inkjet ink stock solutions 1a to 1e having different pHs were used. Arranged.

(Storage stability test)
10 cc of each of the ink stock solutions 1a to 1c was sealed in a sealed screw-type test tube, and then heated in an oven at 70 ° C. for 1 week. The solution absorption of the ink stock solution before the heat treatment is A _Fr , the solution absorption of the ink stock solution after the heat treatment is A _Th, and the storage stability of the ink stock solution from the value of the residual ratio = (A _Th / A _Fr ) × 100 (%) Sex was evaluated.

In the storage stability test of Example 1, the solution absorption of the ink stock solution was measured as follows.
The absorption spectrum of the solution is measured with a UV spectrophotometer (V-560 manufactured by JASCO Corporation) using deionized water added to 0.1 g of an ink stock solution to 500 cc to obtain a quartz cell having a width of 10 mm. The value of absorbance at λmax was taken as A.

Further, the pH of the ink stock solution was measured by the following method.
(Measurement of pH)
The pH of an ink stock solution 4 cc was measured using a pH meter MI229 manufactured by METTLER under conditions of 23 ° C. and 50%.

(Example 2)
Inkjet ink stock solutions 2a to 2e were prepared in the same manner as in Example 1 except that the black dye was changed from Compound A to Compound B [oxidation potential: 1.31 V (vs SCE)]. The storage stability of the ink stock solution was tested.

(Example 3)
Inkjet ink stock solutions 3a to 3e were prepared in the same manner as in Example 1 except that the black dye was changed from Compound A to Compound C [oxidation potential: 1.29 V (vs SCE)]. The storage stability of the ink stock solution was tested.
The obtained results are shown in Table 1.

  Next, the ink stock solutions 1a to 1f were put in a metal container (manufactured by SUS304) that can be sealed, and placed in a thermostat at 70 ° C. for 7 days. After a lapse of time, the metal container was thoroughly washed with water, and discoloration was observed inside the metal container that contained 1a. No discoloration was observed in the metal containers containing 1b to 1f.

Example 4
(Preparation of inkjet black ink)
Ink stock solution 1b 40g
Dye for complementary colors (Compound D) 1.5g
10 g of triethylene glycol monobutyl ether
Glycerin 10g
3 g of triethylene glycol
Surfynol STG 1g
Deionized water (resistance value 18MΩ or more) 34g
To the liquid having the above composition, a liquid having a pH changed using triethanolamine was prepared, and filtered under reduced pressure with a microfilter having an average pore diameter of 0.2 μm to prepare inkjet black inks 4a to 4d having different pHs.

(Storage stability test)
The storage stability test was performed on the above-described 4a to 4d inkjet black inks in the same manner as in Example 1 in which the inkjet ink stock solution was used. The solution absorption of the inkjet black ink was measured in the same manner as in Example 1 except that the amount of the diluted liquid after the addition was changed from 500 cc to 200 cc.
The obtained results are shown in Table 2.

(Inkjet recording)
The above inks 4a to 4d are loaded into a black ink cartridge of an ink jet printer PM-950C manufactured by Epson Corporation. Was evaluated. Also, a sample printed using a black cartridge of Epson PM-950C was used as a reference example. The results are shown in Table 2.

Set the cartridge in the printer, check ink ejection from all nozzles, leave the nozzle cap open for 3 days, print a nozzle check pattern, and evaluate the number of cleanings until there is no non-ejection did.
(Ozone resistance evaluation)
A black density step patch was printed. When 24 hours passed after printing the staircase patch image, the density of each staircase patch portion was measured for reflection density using an X-Rite 310 densitometer equipped with a status A filter as a standard (Ci). A fading test was performed by storing this sample in an ozone gas fading tester that can be adjusted so as to always have an ozone gas concentration of 5 mg / L. As the ozonizer, a commercially available apparatus of a high-pressure discharge system with 5 kV AC voltage applied was used, and the ozone gas concentration was set and controlled using an ozone gas monitor (model: OZG-EM-01) manufactured by APPLICS.
After storage for 2 days, the image density was measured again, the density (Cf) after storage was determined, and the dye residual ratio [%] = (Cf / Ci) × 100 was evaluated. The dye residual ratio was evaluated at three points of reflection density of 1, 1.5, and 2. When the dye residual ratio was 80% or more at any concentration, ◯, when 2 points were less than 80%, The case where it was less than 80% at all the concentrations was marked with x.

From the results of Tables 1 and 2, the ink-jet ink stock solution of the present invention was excellent in storage stability, and the ink composition prepared from the ink stock solution showed excellent storage stability and ejection performance, and was obtained. It can be seen that the image is excellent in ozone resistance.
Even when the image receiving paper used in the present invention was changed to Seiko Epson Co., Ltd. photographic paper, Canon Inc. PR101, the same effect as the above results was observed.

Claims (10)

An azo dye represented by the following general formula (4-1) or (4-2) and having an oxidation potential nobler than 1.0 V (vs SCE) is contained in the medium, and the pH is 3.0 to A black ink stock solution, which is 9.0.

In general formulas (4-1) and (4-2), A ₁ represents an aromatic group or heterocyclic group substituted with an ionic hydrophilic group, and R ₁₀ and R ₁₁ are each independently a hydrogen atom. Represents an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl or arylsulfonyl group, a sulfamoyl group, and R ₁₂ , R ₁₃ and R ₁₄ each represents Independently, hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxy group , Alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, Lilleoxycarbonyloxy group, amino group, acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkyl or Represents an arylthio group, a heterocyclic thio group, an alkyl or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, and R ₂₅ and R ₂₆ each independently represents hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl or arylsulfonyl group or a sulfamoyl group,, Z ₁ is Hame' Represents an electron withdrawing group having a substituent constant σp value of 0.20 or more.   The azo dye contains at least one dye having a λmax of 500 nm to 700 nm and a half-value width of 100 nm or more in an absorption spectrum of a diluted solution normalized to an absorbance of 1.0. Black ink stock solution. The black ink stock solution according to claim 1 or 2, wherein the pH is 6-8 . Black ink stock solution according to any one of claims 1 to 3, characterized in that it further contains a pH adjusting agent. The black ink stock solution according to claim 4 , wherein the pH adjuster is selected from an organic base, an inorganic base, an organic acid, and an inorganic acid. Black ink stock solution according to any one of claims 1 to 5, further characterized by containing a preservative. The preservatives include inorganic substances containing heavy metal ions, quaternary ammonium salts, phenol derivatives, phenoxy ether derivatives, heterocyclic compounds, acid amides, carbamic acids, carbamates, amidines / guanidines, pyridines, diazines, Triazines, pyrrole / imidazoles, oxazole / oxazines, thiazole / thiadiazines, thioureas, thiosemicarbazides, dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics, sodium dehydroacetate, The black ink stock solution according to claim 6 , which is selected from the group consisting of sodium benzoate, p-hydroxybenzoic acid ethyl ester, and a salt thereof. An ink composition comprising the black ink stock solution according to any one of claims 1 to 7 and having a pH of 7 to 9. The ink composition according to claim 8, which is used for ink jet recording. A method for producing an ink composition, wherein the ink composition according to claim 8 or 9 is obtained by using the black ink stock solution according to any one of claims 1 to 7 .