JP5319998B2 - Thermal ink jet recording water-based ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink for thermal inkjet recording, which is excellent in stability with time of glossiness and ejection stability. <P>SOLUTION: The water-based ink for thermal inkjet recording includes polymer particles containing a colorant, a water-insoluble organic compound selected from the group comprising ester compounds and ether compounds, and an alkane polyol. The polymer is essentially constituted of one or more kinds of constitutive units selected from the group comprising a constitutive unit derived from a salt forming group-containing monomer (a), a constitutive unit derived from (meth)acrylate-based macromer (b), a constitutive unit derived from an alkyl ester or aryl ester (c) of (meth)acrylic acid, and a constitutive unit derived from alkanediyl oxide ester (d) of (meth)acrylic acid. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a thermal ink jet recording water-based ink.

  The ink jet recording system is a recording system in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle and attaching them to a recording member. This method is widely spread because it is easy to make full color and is inexpensive, and has many advantages such as the ability to use plain paper as a recording member and non-contact with the object to be printed.

Patent Document 1 discloses an aqueous dispersion of vinyl polymer particles or polyester polymer particles containing a colorant, and water, in order to provide a water-based ink for ink-jet recording having high printing density and excellent glossiness and image clarity. An aqueous dispersion for ink-jet recording containing an insoluble organic compound (excluding fatty acid derivatives) is disclosed.
Patent Document 2 includes at least a pigment coated with a water-insoluble polymer, water, and a water-soluble organic compound in order to provide an ink composition having excellent gloss of printed images and excellent color developability on plain paper. In the water-based ink composition, a water-based ink composition further containing a plasticizer is disclosed.
However, these inks are not satisfactory in terms of glossy stability over time and ejection stability when used in a thermal system as an ink jet recording system.

JP 2007-77375 A JP 2007-277291 A

  It is an object of the present invention to provide a thermal ink jet recording water-based ink having excellent gloss stability over time and ejection stability.

In the present invention, (A) polymer particles containing a colorant, (B) the maximum weight that can be dissolved in 100 g (20 ° C.) of water is 5 g or less, and one kind selected from the group consisting of ester compounds and ether compounds A thermal ink jet recording aqueous ink comprising the above water-insoluble organic compound and (C) an alkane polyol having 4 to 12 carbon atoms, wherein the polymer is a structural unit derived from the salt-forming group-containing monomer (a); , A structural unit derived from a (meth) acrylic acid ester-based macromer (b), a structural unit derived from an alkyl ester or aryl ester (c) of (meth) acrylic acid, and (meth) represented by the following general formula (1) Thermally consisting essentially of one or more structural units selected from the group consisting of structural units derived from alkanediyl oxide esters (d) of acrylic acid Providing an expression water-based ink for inkjet recording.
^{_{CH 2 = C (R 12)}} COO (R 13 O) q R 14 (1)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)

  ADVANTAGE OF THE INVENTION According to this invention, the water-system ink for thermal system inkjet recording excellent in the glossy temporal stability and discharge stability can be provided.

The thermal ink jet recording aqueous ink of the present invention contains (A) specific polymer particles containing a colorant, (B) specific water-insoluble organic compound, and (C) an alkane polyol having 4 to 12 carbon atoms. The ink is characterized by excellent discharge stability.
The ink used in the thermal ink jet recording apparatus has a problem that the substance attached to the nozzle is deteriorated by heat and inferior in ejection stability.
In response to this problem, the thermal ink jet recording water-based ink of the present invention uses a specific water-insoluble organic compound and a specific alkane polyol to reduce the change in gloss, and to use the water-insoluble organic compound as a nozzle. It makes it difficult to adhere and has excellent discharge stability. This is presumably because the water-insoluble organic compound can be present as stably as possible in the polymer particles. In addition, the polymer particles themselves use a specific polymer, and are difficult to adhere to the nozzle, and are excellent in ejection stability. Hereinafter, each component used in the present invention will be described.

[(B) Water-insoluble organic compound]
In the present invention, (B) the maximum weight that can be dissolved in 100 g of water (20 ° C.) is 5 g or less, and one or more water-insoluble organic compounds selected from the group consisting of ester compounds and ether compounds (hereinafter simply referred to as “ Also referred to as “water-insoluble organic compound”.
The water-insoluble organic compound is considered to be contained in the polymer particles to improve its flexibility. Furthermore, it is considered that the glossiness of the printed matter is improved by increasing the fusing property between the polymer particles discharged from the nozzle, the polymer particles are uniformly diffused on the special paper, and the printing surface becomes smooth.

The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,000, from the viewpoint of improving the glossiness and image clarity of the ink.
The maximum weight that can be dissolved in 100 g of water (20 ° C.) is 5 g or less, preferably 3 g or less, more preferably 1 g or less.

  The water-insoluble organic compound is preferably an ester compound and / or an ether compound from the viewpoint of easy inclusion in the polymer particles, and (f) an ester or an ether compound having two or more ester or ether bonds in the molecule. And / or (g) the molecule consists of at least one ester or ether bond and a carboxy group, a sulfuric acid group, a sulfonic acid group, a phosphonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group. An ester or ether compound having one or more functional groups selected from the group is more preferred. (F) The ester or ether bond of the compound is preferably 2 to 3, and may have an ester bond and an ether bond. (G) As for the ester or ether bond of a compound, 1-3 are preferable. The number of functional groups is preferably 1 to 3. A phosphoric acid residue means the remaining phosphoric acid group in which a part of phosphoric acid was esterified.

The water-insoluble organic compound is preferably an alkylene oxide adduct from the viewpoint of improving ejection stability as a thermal ink jet recording ink.
In order to produce an alkylene oxide adduct, it can be obtained by using an alkylene oxide adduct as a raw material alcohol for ester or ether.
The alkylene oxide adduct is preferably one using at least one selected from the group consisting of ethylene oxide and propylene oxide, and when both are used, random addition or block addition may be used.

  Among the ester compounds, an ester obtained from a monovalent carboxylic acid or a salt thereof and a polyhydric alcohol, an ester obtained from a polyvalent acid (polyvalent carboxylic acid, phosphoric acid) or a salt thereof and a monohydric alcohol is preferred, and aliphatic. Or it is more preferable to have two aromatic carboxylic acid ester groups or three phosphoric acid ester groups. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like. Of the ether compounds, polyhydric alcohol ether compounds are preferred.

  Examples of monovalent carboxylic acids include linear or branched aliphatic carboxylic acids having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, Linear aliphatic carboxylic acids such as palmitic acid, branched aliphatic carboxylic acids such as pivalic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid), and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, , Benzoic acid) and the like.

Examples of the polyvalent acid include aliphatic carboxylic acids having 2 to 12 carbon atoms such as maleic acid, fumaric acid, itaconic acid, succinic acid, adipic acid and sebacic acid; and 6 to 12 carbon atoms such as phthalic acid and trimellitic acid. Aromatic carboxylic acid, phosphoric acid and the like can be mentioned.
The monohydric alcohol is a linear or branched aliphatic alcohol having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, ethyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol). , Aromatic alcohols having 6 to 12 carbon atoms (for example, phenol) and alkylene oxide compounds thereof.

  Examples of the polyhydric alcohol include polyhydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin, and alkylene oxide compounds thereof. A saturated or unsaturated fatty acid or alcohol can be used.

Specific examples of the water-insoluble organic compound include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) cycloalkane (ken) carboxylic acid ester, (4) phosphoric acid ester, (5) Oxy acid ester, (6) glycol ester, (7) epoxy ester, (8) polyester, (9) glyceryl alkyl ether, (10) glyceryl alkyl ester, (11) glycol alkyl ether, (12) glycol alkyl ester, (13) Ether or ester of trimethylolpropane, (14) Ether or ester of pentaerythritol, and the like.
(1) Aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, and (3) cycloalkane (ken) carboxylic acid ester are preferably compounds represented by the following formula (2).

(.R wherein, R ¹ and R ² are each independently a hydrogen atom, or a hydrocarbon group having 1 to 22 carbon atoms, R ³ is showing a divalent hydrocarbon group having 1 to 18 carbon atoms ¹ and R ² may be the same or different, except when R ¹ and R ² are both hydrogen atoms, R ^{1 to} R ³ may have a substituent, and m and n are Each independently represents an average addition mole number of 0 to 30, and AO represents an alkanediyloxy group.)

R ¹ and R ² are preferably a linear or branched alkyl or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, and 7 carbon atoms from the viewpoint of improving the gloss of printed matter. -23, preferably an aralkyl group having 7 to 11 carbon atoms, or an aryl group having 6 to 22 carbon atoms, preferably 6 to 10 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group. Butyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group, phenyl group, benzyl group and the like. The same applies to the following equations.
R ³ is preferably a divalent aliphatic hydrocarbon group, a cyclic hydrocarbon group or an aromatic hydrocarbon group, preferably 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 carbon atoms. An alkanediyl group (alkylene group) or an alkenylene group having 8 to 8 carbon atoms, an arylene group having 6 to 10 carbon atoms, more preferably a phenylene group, or a cyclic saturated or unsaturated hydrocarbon group having 3 to 8 carbon atoms. Specifically, ethylene group, trimethylene group, propane-1,2-diyl group, tetramethylene group, heptamethylene group, hexamethylene group, pentane-1,5-diyl group, octamethylene group, dodecamethylene group, phenylene Groups and the like. The same applies to the following equations.
m and n are each independently preferably 0 to 20, more preferably 0 to 15, still more preferably 1 to 15, particularly preferably 2 to 14, and most preferably 2 to 12.

AO is the number of carbon atoms such as ethyleneoxy group (EO), propyleneoxy group (trimethyleneoxy group or propane-1,2-diyloxy group) (PO), butyleneoxy group (tetramethyleneoxy group etc.) (BO), etc. 2 to 4 alkanediyloxy groups (alkyleneoxy groups), and when m and n are 2 or more, AO may be the same or different, and when they are different, AO may be added in blocks or randomly. It may be.
Examples of the substituent that R ^{1 to} R ³ may have include halogen atoms such as fluorine, chlorine and bromine atoms, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, phenyloxy Aryloxy groups such as oxycarbonyl groups such as methoxycarbonyl groups, acyl groups such as acetyl and benzoyl groups, acyloxy groups such as acetyloxy groups, cyano groups, nitro groups, hydroxyl groups, carboxy groups, oxo groups, epoxy groups , Ether groups, ester groups and the like (these are collectively referred to as “substituents”). These substituents may be one or a combination of two or more.
The substituent that R ³ may have is preferably —CO (O) — (AO) _L —R ⁴ . In the formula, AO is the same as described above. L has the same meaning as m described above, and the preferred range is also the same. R ⁴ has the same meaning as R ¹ described above, and the preferred range is also the same. In this case, R ³ is preferably an aromatic hydrocarbon group.

(1) The aliphatic carboxylic acid ester is more specifically a compound in which, in the formula (2), R ³ is a divalent aliphatic hydrocarbon group which may have a substituent. preferable. Examples of this substituent include the above-described substituents.
Specific examples of the aliphatic carboxylic acid ester include dimethyl adipate, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis (butyldiethylene glycol) adipate, dimethyl sebacate, diethyl sebacate Examples thereof include aliphatic dibasic acid esters such as keto, dibutyl sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate and bis (2-ethylhexyl) azelate. Among these, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (butyldiethylene glycol) adipate, bis (octoxypolyethylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, EO average addition moles m and n = 1 to 4), bis (octoxypolypropylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, average number of added moles of PO and n = 1 to 6), bis (octoxypolyethylene glycol / polypropylene) Glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, EO and PO total added moles m and n = 4-12, block addition), bis [octoxypoly (ethylene glycol propylene glycol)] adipate ( R ¹ and R ² are both 2 -Ethyl hexyl, EO and PO total average addition moles m and n = 4-12, random addition), diethyl sebacate, dibutyl sebacate, diisobutyl sebacate, etc. Diesters are particularly preferred.

  (2) More specifically, the aromatic carboxylic acid ester is more preferably a compound represented by the following formula (3).

(In the formula, R ¹ and R ² have the same meaning as described above, and may be the same or different. AO, m and n have the same meaning as described above, and when m and n are 2 or more, AO May be the same or different.)

Specific examples of the aromatic carboxylate include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, octyl benzyl phthalate, nonyl Phthalate esters such as benzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate, tributyl trimellitate, Trimellitic acid esters such as triisobutyl trimellitate and tri (2-ethylhexyl) trimellitate It is below.
Among these, carbon number 3 such as phthalic acid diester having an aliphatic alcohol residue having 1 to 5 carbon atoms such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, octyl benzyl phthalate, nonyl benzyl phthalate, stearyl benzyl phthalate Benzyl phthalate having -18 alkyl groups, bis (octoxypolyethylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average addition number m of EO and n = 1-5), bis (octoxy Polypropylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average added moles of PO m and n = 1 to 4), bis (octoxypolyethylene glycol / polypropylene glycol) phthalate (R ¹ and R ² are 2-Echi both Hexyl, each total average addition mole number m and n = 4 to 12 of EO and PO, block addition), bis [Okutokishipori (ethylene glycol-propylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, EO and Phthalic acid diesters such as the total average number of added moles of PO and n = 4 to 12, random addition), trimellitic acid triesters having octoxypolyalkylene glycol residues similar to those of the phthalic acid diesters at each end, And trimellitic acid triesters having an aliphatic alcohol residue of 3 to 5 carbon atoms such as tributyl trimellitate and triisobutyl trimellitate are particularly preferred.

  (3) More specifically, the cycloalkane (ken) carboxylic acid ester is more preferably a cyclohexane (cene) carboxylic acid ester represented by the following formula (4). Examples of the cycloalkane (ken) group include a cyclic hydrocarbon group which may have one unsaturated group having 3 to 8 carbon atoms.

(In the formula, R ¹ and R ² have the same meaning as described above, and may be the same or different. AO, m and n have the same meaning as described above, and when m and n are 2 or more, AO May be the same or different.)
Specific examples of the cycloalkane (ken) carboxylic acid ester include cyclohexane carboxylic acid esters such as 1,2-cyclohexanedicarboxylic acid dibutyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester, and 3,4-cyclohexene dicarboxylic acid dibutyl ester. And cyclohexene carboxylic acid esters such as 3,4-cyclohexene carboxylic acid diisononyl ester.
(4) The phosphate ester is preferably a compound represented by the following formula (5).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different.)
Specific examples of phosphate esters include tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl A phosphate etc. are mentioned. Among these, phosphate esters having a C5-C9 alkoxyalkyl group such as tris (butoxyethyl) phosphate, phosphate esters having a C4-12 aliphatic hydrocarbon group such as tributyl phosphate, tris ( Butoxyethyl) phosphates, tricresyl phosphates, trixylenyl phosphates, cresyl diphenyl phosphates, and other phosphate esters having an aromatic hydrocarbon group of 7 to 12 carbon atoms are particularly preferred. The phosphoric acid ester is preferably a phosphoric acid di- or triester.

  (5) The oxyacid ester is preferably a compound represented by the following formula (6).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the oxyester include triethyl acetylcitrate, tributyl acetylcitrate, methyl acetylricinoleate and the like.

  (6) The glycol ester is preferably a compound represented by the following formula (7).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the glycol ester include diethylene glycol dibenzoate and triethylene glycol di (2-ethylhexoate).

  (7) The epoxy ester is preferably a compound represented by the following formula (8).

(In the formula, R ¹ has the same meaning as described above. R ⁴ and R ⁵ each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁶ represents an alkanediyloxy group having 1 to ⁶ carbon atoms. Show.)
Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

  (8) The polyester is preferably a compound represented by the following formula (9).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above and may be the same or different. P represents a number of 1 to 18, preferably 1 to 10.)
Specific examples of the polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.
(9) Specific examples of the glyceryl alkyl ether include glyceryl monoether, glyceryl diether, and glyceryl triether. In these, the glyceryl monoether which has a C8-C30 linear or branched alkyl group is preferable. The alkyl group has 8 to 30 carbon atoms, preferably 8 to 22 carbon atoms, and more preferably 8 to 14 carbon atoms.
Examples of the alkyl group include 2-ethylhexyl, (iso) octyl, (iso) decyl, (iso) dodecyl, (iso) myristyl, (iso) cetyl, (iso) stearyl, and (iso) behenyl groups.
There is no restriction | limiting in particular about the position of an alkyl group, Either 1-alkyl glyceryl monoether and 2-alkyl glyceryl monoether may be sufficient.

(10) Specific examples of the glyceryl alkyl ester include glyceryl monoalkyl ester, glyceryl dialkyl ester, and glyceryl trialkyl ester.
Among these, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid) Linear aliphatic carboxylic acids such as branched aliphatic carboxylic acids such as pivalic acid) esters are preferred. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.

  (11) Specific examples of glycol alkyl ether include glycol monoalkyl ether and glycol dialkyl ether. Examples of the glycol of the compound (11) include ethylene glycol, neopentyl glycol, and the like. As the alkyl group, a linear chain having 1 to 22 carbon atoms, preferably 6 to 20 carbon atoms, more preferably 8 to 18 carbon atoms. Or a branched alkyl group is mentioned.

Among these, from the viewpoints of glossiness and image clarity, the compounds (1) to (5) and (9) are preferred, and aliphatic di- or tricarboxylic acid esters, (2) aromatic carboxylic acid esters, (3 It is preferably at least one selected from the group consisting of cycloalkane (ken) carboxylic acid esters and (4) phosphoric acid esters, aliphatic dicarboxylic acid esters, aromatic di- or tricarboxylic acid esters, cycloalkane (ken) It is preferable that it is 1 or more types chosen from the group which consists of carboxylate ester and phosphate ester.
Of these, the alkylene oxide adducts represented by the general formulas (2) to (4) are preferable from the viewpoint of ejection stability.

[(C) C4-12 alkane polyol]
In the present invention, (C) an alkane polyol having 4 to 12 carbon atoms (hereinafter, also simply referred to as “alkane polyol”) stabilizes a water-insoluble organic compound in the polymer particles, thereby improving gloss over time and ejection stability. It is thought to improve the performance.
Examples of the alkane polyol having 4 to 12 carbon atoms used in the present invention include linear or branched alkane polyols having 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms, and more preferably 8 to 10 carbon atoms. . The alkane polyol has 2 or more hydroxyl groups, preferably 2 to 6, and more preferably 2 to 4.
The molecular weight of the alkane polyol is preferably from 100 to 500, more preferably from 100 to 300.
Specific examples of the alkanediol having 4 to 12 carbon atoms include 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,3 -Butanediol, 1,2-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-pentanediol, 2,4-diethyl-1,5-pentanediol, 1 2,4-trimethyl-1,3-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,6-hexanediol, 2- Examples include ethyl-1,3-hexanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-decanediol, 1,2-dodecanediol, and the like.
Specific examples of the alkanetriol having 4 to 12 carbon atoms include 1,2,6-hexanetriol, 1,2,3-butanetriol, pentanetriol, 1,2,4-butanetriol and the like.
Among these, from the viewpoint of stability over time, alkane diols having 4 to 12 carbon atoms are preferable, alkane diols having 4 to 12 carbon atoms each having a hydroxyl group on adjacent carbon atoms, more preferably 4 to 12 1,2-alkanediol is more preferable, and 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol are more preferable.

It is considered that the alkane polyol has a high affinity with the water-insoluble organic compound and contributes to the stability of the water-insoluble organic compound in the polymer particles. From this viewpoint, the absolute value of the difference in the solubility parameter (SP value) between the alkane polyol and the water-insoluble organic compound (hereinafter also simply referred to as “SP value”) is preferably 6 or less, and preferably 5 or less. Is more preferable, 4.5 or less is more preferable, and 4 or less is still more preferable.
11-18 are preferable and, as for SP value of alkane polyol, 12-15 are more preferable.
7-12 are preferable and, as for SP value of a water-insoluble organic compound, 9-11 are more preferable.

From the viewpoint of stably presenting the water-insoluble organic compound in the polymer particle, it is preferable that the affinity between the water-insoluble organic compound and the polymer particle is high, and the absolute difference in SP value between the polymer of the polymer particle and the water-insoluble organic compound is preferred. The value is preferably 6 or less, more preferably 5 or less, more preferably 4.2 or less, and still more preferably 4 or less.
10-12 are preferable and, as for SP value of the polymer of a polymer particle, 10.8-11.5 are more preferable.

The solubility parameter (SP value) referred to in the present specification was determined based on the following Fedors equation by the Fedors method [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)]. The value δ [(MPa) ^1/2 ], which is obtained from the square root of the ratio of the sum of evaporation energy of atoms or atomic groups (Δei) of the chemical structure of the compound to the sum of molar volumes (Δvi).
Fedors equation: δ = (ΣΔei / ΣΔvi) ^1/2

[(A) Polymer Particles Containing Colorant]
(Coloring agent)
The colorant used in the present invention is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance, dispersion stability and resistance From the viewpoint of abrasion, pigments and hydrophobic dyes are preferable. Among them, it is preferable to use a pigment in order to express the high weather resistance which has been recently demanded.
When the pigment and the hydrophobic dye are used in an aqueous ink, it is necessary to use a surfactant and a polymer to form fine particles that are stable in the ink. In particular, from the viewpoints of bleeding resistance, water resistance, and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment blue, and C.I. I. One or more types of products selected from the group consisting of pigment green are listed.
Examples of extender pigments include silica, calcium carbonate, and talc.

The hydrophobic dye is not particularly limited as long as it can be contained in the polymer particles. The hydrophobic dye is dissolved in an amount of 2 g / L or more, preferably 20 to 500 g / L (25 ° C.) with respect to the organic solvent (preferably methyl ethyl ketone) used in the production of the polymer from the viewpoint of efficiently containing the dye in the polymer. What to do is desirable.
Examples of the hydrophobic dye include oil-soluble dyes and disperse dyes. Among these, oil-soluble dyes are preferable.
Examples of the oil-soluble dye include C.I. I. Solvent Black, C.I. I. Solvent Yellow, C.I. I. Solvent Red, C.I. I. Solvent Violet, C.I. I. Solvent Blue, C.I. I. Solvent Green, and C.I. I. One or more types of products selected from the group consisting of Solvent Orange are listed, which are commercially available from Orient Chemical Co., Ltd., BASF Corp. and others.
The above colorants can be used alone or in admixture of two or more at any ratio.

(Polymer particles)
In the present invention, the polymer particles are used to improve glossiness by interaction with a water-insoluble organic compound. Moreover, in order to disperse | distribute a coloring agent stably, a coloring agent is contained in a polymer particle.
(polymer)
The polymer used in the present invention includes a structural unit derived from the salt-forming group-containing monomer (a) (hereinafter also referred to as “component (a)”), a structural unit derived from the (meth) acrylate compound (b), and specifically Includes a structural unit derived from a (meth) acrylic acid ester-based macromer (b) (hereinafter also referred to as “component (b)”), an alkyl ester or aryl ester (c) of (meth) acrylic acid (hereinafter referred to as “(c)”. From the structural unit derived from the structural unit derived from the component unit) and the alkanediyl oxide ester (d) of (meth) acrylic acid represented by the following general formula (1) (hereinafter also referred to as “component (d)”) It is preferable from the viewpoint of ejection stability that it consists essentially of one or more structural units selected from the group consisting of: When the water-based ink of the present invention is used for a thermal ink jet recording apparatus, it is considered that even if the polymer adheres to the ink ejection nozzle, the fixation of the polymer can be reduced by desorption or decomposition.
^{_{CH 2 = C (R 12)}} COO (R 13 O) q R 14 (1)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)
Here, “essentially” means a range that does not impair the effects of the present invention, preferably 1% by weight or less, more preferably 0.5% by weight or less, and still more preferably 0.1% by weight or less. Although it may have a structural unit derived from a component, it means that it is preferable not to have a structural unit derived from another monomer component.
This polymer comprises a monomer mixture (hereinafter also referred to as “monomer mixture”) containing (a) component and one or more components selected from the group consisting of component (b), component (c) and component (d). It is preferable to obtain by copolymerization.

(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the dispersion stability of the resulting dispersion. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group, and a carboxy group is particularly preferable.
Examples of the salt-forming group-containing monomer include a cationic monomer and an anionic monomer. Examples thereof include those described in paragraph [0022] of JP-A-9-286939.
Representative examples of the cationic monomer include unsaturated amine-containing monomers and unsaturated ammonium salt-containing monomers. Among these, N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide and vinylpyrrolidone are preferable.

Representative examples of anionic monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyciethyl phosphate Etc.
Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of dispersion stability of the dispersion of polymer particles containing a colorant and ink ejection stability.

The (b) (meth) acrylic acid ester-based macromer (hereinafter, also simply referred to as “(b) macromer”) is used from the viewpoint of enhancing the dispersion stability of the polymer particles when the polymer particles contain a colorant. it can. The (meth) acrylic acid ester-based macromer means one having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group present at one end of the macromer.
(B) The macromer includes a macromer which is a monomer having a polymerizable unsaturated group having a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000. In addition, the number average molecular weight of (b) macromer is measured using polystyrene as a standard substance by gel chromatography using chloroform containing 1 mmol / L of dodecyldimethylamine as a solvent.
Among the macromers (b), from the viewpoint of dispersion stability of polymer particles, styrene macromers and aromatic group-containing (meth) acrylate macromers having the polymerizable functional group at one end are exemplified.
Examples of the styrenic macromer include a styrene monomer homopolymer or a copolymer of a styrene monomer and another monomer. Examples of the styrene monomer include styrene, 2-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl naphthalene, chlorostyrene, and the like.
Examples of the aromatic group-containing (meth) acrylate-based macromer include a homopolymer of an aromatic group-containing (meth) acrylate or a copolymer thereof with another monomer. As an aromatic group-containing (meth) acrylate, an arylalkyl having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate having an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a group or a substituent containing a hetero atom In addition, examples of the substituent containing a hetero atom include a halogen atom, an ester group, an ether group, and a hydroxy group. Examples include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, and benzyl (meth) acrylate is particularly preferable.
Moreover, as another monomer copolymerized, the acrylonitrile etc. which are represented by following formula (10) are preferable.

(In the formula, x and y represent the average added mole number, and x / y = 6/4 to 10/0.)
The content of the styrene monomer in the styrene macromer or the aromatic group-containing (meth) acrylate in the aromatic group-containing (meth) acrylate macromer is preferably 50% from the viewpoint of increasing the affinity with the colorant. % Or more, more preferably 70% by weight or more.
(B) The macromer may have a side chain composed of another structural unit such as an organopolysiloxane. This side chain can be obtained, for example, by copolymerizing a silicone macromer having a polymerizable functional group at one end represented by the following formula (11).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 11)
(In the formula, t represents a number of 8 to 40).
(B) Styrenic macromers that are commercially available as macromers include, for example, trade names of Toa Gosei Co., Ltd., AS-6 (S), AN-6 (S), HS-6 (S), and the like. It is done.

(C) Alkyl ester or aryl ester of (meth) acrylic acid can be used from the viewpoint of enhancing storage stability.
(C) The alkyl ester of (meth) acrylic acid includes (meth) acrylic acid ester having an alkyl group having 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms, more preferably 1 to 12 carbon atoms. .
Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (meth) acrylic acid (iso or tert-) butyl, (meth) acrylic acid (iso ) Amyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid (iso) octyl, (meth) acrylic acid (iso) decyl, (meth) acrylic acid (iso) dodecyl, ( Examples include (meth) acrylic acid (iso) stearyl.
Specific examples of the (meth) acrylic acid aryl ester include 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, such as phenyl (meth) acrylate, benzyl (meth) acrylate, and phenoxyethyl (meth) acrylate. More preferable examples include aryl groups having 6 to 12 carbon atoms, arylalkyl groups, and (meth) acrylic acid aryl esters which may have an alkoxy group.
In the present specification, “(iso or tert-)” and “(iso)” mean that both of these groups are present and not present, and these groups are present. If not, it indicates normal. “(Meth) acrylic acid” refers to acrylic acid and / or methacrylic acid.
Among the above, (meth) acrylic acid aryl ester is preferable, and benzyl methacrylate is more preferable from the viewpoint of increasing the adsorptive power to the colorant and obtaining higher storage stability and printing density of the ink.

(D) Alkanediyl oxide ester of (meth) acrylic acid The polymer used in the present invention assists the stability of the dispersion of polymer particles containing the colorant after the colorant is contained in the polymer. From the viewpoint of improving the discharge stability of the resin, it is preferable to have a structural unit derived from an alkanediyl oxide ester (d) of (meth) acrylic acid represented by the following general formula (1).
^{_{CH 2 = C (R 12)}} COO (R 13 O) q R 14 (1)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)
Specific examples of R ¹³ include an ethylene group, a trimethylene group, or a propane-1,2-diyl group. q means the average number of added moles, preferably 7 to 30, and more preferably 8 to 23. When q is 2 or more, R ¹³ may be the same or different and may be either block addition or random addition.
R ¹⁴ is preferably a linear or branched alkyl group having 3 to 22 carbon atoms, more preferably 8 to 18 carbon atoms. Specifically, methyl group, ethyl group, (iso) propyl group, (iso or tert-) butyl group, (iso) amyl group, hexyl group, 2-ethylhexyl group, (iso) octyl group, (iso) decyl Group, (iso) dodecyl group, (iso) stearyl group, behenyl group and the like.
However, when the average added mole number q is 4 or less, R ¹⁴ is preferably a linear or branched alkyl group having 3 to 22 carbon atoms from the viewpoint of ink ejection stability and storage stability.

As a suitable example of the component (d), polyethylene glycol having an alkyl group at the terminal (n = 2 to 30, n represents the average number of added moles of alkanediyloxy group; the same shall apply hereinafter) (meth) acrylate, at the terminal Polypropylene glycol having an alkyl group (n = 2 to 30) (meth) acrylate, poly (ethylene glycol (n = 1 to 15) / propylene glycol (n = 1 to 15)) (meth) acrylate having an alkyl group at the terminal Etc.
Particularly preferred specific examples include 2-ethylhexyloxypolyethylene glycol (n = 4) methacrylate, 2-ethylhexyloxypolyethylene glycol (n = 9) methacrylate, methoxypolyethylene glycol (n = 9) methacrylate and the like.
Specific examples of the commercially available component (d) include monofunctional acrylate monomers (NK esters) EH-4E, EH-9E, M-90G from Shin-Nakamura Chemical Co., Ltd. Mer series, 50PEP-300, 50POEP-800B and the like.
The components (a) to (d) can be used alone or in admixture of two or more.

The content of the components (a) to (d) in the monomer mixture at the time of polymer production (content as an unneutralized amount; the same applies hereinafter) or derived from the components (a) to (d) in the water-insoluble polymer The content of the structural unit is as follows.
The content of component (a) is preferably 2 to 40% by weight, more preferably 2 to 30% by weight, and particularly preferably 3 to 20% by weight from the viewpoint of dispersion stability of the resulting dispersion.
The content of the component (b) is preferably 1 to 25% by weight, more preferably 5 to 20% by weight, particularly from the viewpoint of enhancing the interaction with the colorant.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight from the viewpoints of glossiness and image clarity.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 35% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The total content of [component (a) + component (d)] in the monomer mixture is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, from the viewpoint of dispersion stability of the resulting dispersion. is there. The total content of [component (b) + component (c)] is preferably 30 to 90% by weight, more preferably 40 to 80% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
Further, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.02 to 0.8, more preferably 0.03, from the viewpoint of glossiness and image clarity. It is -0.6, More preferably, it is 0.05-0.5.
The weight ratio [(a) / (c)] between the component (a) and the component (c) is preferably 0.1 to 0.8 from the viewpoint of achieving both dispersion stability and ejection stability. 2-0.5 is still more preferable.
The weight ratio [(b) / (c)] of the component (b) to the component (c) is preferably 0.05 to 0.5 from the viewpoint of achieving both ejection stability and print density, and is preferably 0.1 -0.4 is still more preferable.

(Manufacture of polymers)
The polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol, and propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate. Among these, methanol, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, or a mixed solvent of one or more of these and water are preferable.
In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used.
The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

Since the polymerization conditions of the monomer mixture vary depending on the type of radical polymerization initiator, monomer, and solvent used, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C, and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation or by removing unreacted monomers and the like by membrane separation, chromatographic method, extraction method and the like.

The weight average molecular weight of the polymer is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, and even more preferably from 10,000 to 300,000, from the viewpoint of printing density, glossiness, and dispersion stability of the colorant. 20,000 to 300,000 is particularly preferable. In addition, the weight average molecular weight of the polymer was measured by the method shown in the Examples.
When the polymer has (a) a salt-forming group derived from a salt-forming group-containing monomer, the polymer is used after being neutralized with a neutralizing agent. As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group in the polymer. For example, hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, gluconic acid, glyceric acid and other acids, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine , Bases such as trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, and tributylamine.

The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%.
Here, the degree of neutralization can be determined by the following formulas (12) and (13) when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100 (12)
When the salt-forming group is a cationic group, it can be determined by the following formula.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × polymer weight (g) / (36.5 × 1000)]} × 100 (13)
The acid value and amine value can be calculated from the structural unit of the polymer. Alternatively, it can also be determined by a method in which a polymer is dissolved in an appropriate solvent (for example, methyl ethyl ketone) and titrated. The acid value or amine value of the polymer is preferably 50 to 200, more preferably 50 to 150.

(Production method of water-based ink for thermal inkjet recording)
The thermal ink jet recording aqueous ink of the present invention comprises (A) polymer particles containing a colorant, (B) a water-insoluble organic compound, and (C) an alkane polyol. Although there is no limitation in the manufacturing method of such an aqueous ink, For example, it can obtain by following process (1)-(3).
Step (1): Step of obtaining a dispersion of polymer particles containing a colorant by dispersing a mixture containing a polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent Step (2): Step Step of removing the organic solvent from the dispersion obtained in (1) to obtain an aqueous dispersion of polymer particles containing a colorant Step (3): containing a colorant obtained in Step (2) Mixing water dispersion of polymer particles, water-insoluble organic compound and alkane polyol

In step (1), first, the polymer is dissolved in an organic solvent, and the resulting organic solvent solution is mixed with a colorant, water, and if necessary, a neutralizing agent, a surfactant, and the like. A method for obtaining an oil-in-water dispersion is preferred. In the mixture, the colorant is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, the organic solvent is preferably 10 to 70% by weight, more preferably 10 to 50% by weight, and the polymer is 2 to 2% by weight. It is preferably 40% by weight, more preferably 3 to 20% by weight, and water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the polymer has a salt-forming group, it is preferable to use a neutralizing agent, but the degree of neutralization is not particularly limited. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the water-insoluble polymer. Examples of the neutralizing agent include those described above. Further, the polymer may be neutralized in advance.

  Examples of the organic solvent include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. Preferably, the maximum weight that can be dissolved in 100 g of water (20 ° C.) is preferably 5 g or more, more preferably 10 g or more, more specifically preferably 5 to 80 g, more preferably 10 to 50 g. In particular, methyl ethyl ketone and methyl isobutyl ketone are preferred.

There is no restriction | limiting in particular in the dispersion method of the yes mixture in the said process (1). Although the average particle size of the polymer particles can be atomized until the desired particle size is obtained without pre-dispersing, it is preferably pre-dispersed using a commonly used mixing and stirring device such as a media-type disperser. After that, it is preferable to control the average particle size of the polymer particles to be a desired particle size by further applying a shear stress to perform further dispersion. 5-50 degreeC is preferable and, as for the temperature in dispersion | distribution of a process (1), 10-35 degreeC is still more preferable.
Examples of means for applying the shear stress of this dispersion include a bead mill, a high-pressure homogenizer [Izumi Food Machinery Co., Ltd., trade name], a mini-lab type 8.3H type (Rannie Co., trade name) represented by a homovalve type high-pressure homogenizer, micro Examples thereof include a chamber type high-pressure homogenizer such as a fluidizer [Microfluidics, trade name] and a nanomizer [Nanomizer, trade name]. A plurality of these devices can be combined. Among these, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the colorant.

In the step (2), an aqueous dispersion of polymer particles containing a colorant is obtained by distilling off the organic solvent from the dispersion obtained in the step (1) by a known method to form an aqueous system. Can do. The organic solvent in the aqueous dispersion containing the obtained polymer particles is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. The amount of the residual organic solvent is preferably 0.1% by weight or less, and more preferably 0.01% by weight or less.
The obtained aqueous dispersion of polymer particles containing the colorant is one in which the solid content of the polymer containing the colorant is dispersed in water as the main solvent. Here, the form of the polymer particles is not particularly limited as long as the composite particles are formed of at least a colorant and a polymer. For example, a particle form in which a colorant is included in a polymer, a particle form in which a colorant is uniformly dispersed in a polymer, a particle form in which a colorant is exposed on the surface of a polymer particle, and the like are included.

In the step (3), the water dispersion obtained in the step (2), the water-insoluble organic compound and the alkane polyol may be mixed. Preferably, the water dispersion obtained in the step (2) and the water-insoluble organic compound are mixed and subjected to a dispersion treatment by applying a shear stress, and then an alkane polyol is added. Thereby, an aqueous dispersion of polymer particles containing the water-insoluble organic compound and the colorant, in which at least a part of the water-insoluble organic compound is contained in the polymer particles, can be obtained. The alkane polyol may be present together with the water-insoluble organic compound in the polymer particles, or may be present in the aqueous dispersion.
The means for applying the shear stress is the same as in the step (2). An ultrasonic homogenizer can also be used. For example, as the ultrasonic homogenizer, those having a frequency of 20 to 2000 kHz and a wattage per liter of the total reaction liquid amount of preferably 20 to 1000 W, more preferably 50 to 800 W are desirable. Such an ultrasonic disperser is commercially available from Nippon Seiki Seisakusho, Alex Co., Ltd. A plurality of these devices can be combined. 5-50 degreeC is preferable and, as for the temperature in dispersion | distribution of a process (3), 10-35 degreeC is still more preferable.

The thermal ink jet recording aqueous ink of the present invention includes a wetting agent, a penetrating agent, a dispersing agent, a viscosity modifier, an antifoaming agent, an antifungal agent, a rust preventive agent and the like that are usually used in an ink jet recording aqueous ink. Also good. Alternatively, an aqueous dispersion obtained by adding a wetting agent or a penetrating agent together with an alkane polyol in the step (3) may be used as a water-based ink.
The average particle diameter of the polymer particles in the obtained water-based ink is preferably 0.01 to 0.5 μm, more preferably 0.03 to 0.3 μm, from the viewpoint of preventing clogging of the nozzles of the printer and dispersion stability. Especially preferably, it is 0.05-0.2 micrometer. The average particle diameter can be measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100. The refractive index of water (1.333) is input as the refractive index of the dispersion solvent. The measurement concentration is usually about 5 × 10 ⁻³ wt%.

(Water-based ink for inkjet recording)
The content of each component and the ratio thereof in the aqueous ink for thermal ink jet recording of the present invention are as follows.
In the water-based ink, the content of the water-insoluble organic compound is preferably 0.1 to 5% by weight, more preferably 0.2 to 3% by weight, particularly 0.3 to 2% by weight from the viewpoint of improving glossiness. preferable.
In the water-based ink, the content of polymer particles (the solid content excluding the water-insoluble organic compound and the colorant. The same applies hereinafter) is preferably 0.5 to 10% by weight from the viewpoint of printing density and glossiness. 8 wt% is more preferable, and 1 to 5 wt% is particularly preferable.
In the water-based ink, the content of the colorant is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and particularly preferably 2 to 8% by weight from the viewpoint of printing density.
In the water-based ink, the content of the alkane polyol is preferably 0.2 to 10% by weight, more preferably 0.3 to 8% by weight, and more preferably 0.5 to 5% by weight from the viewpoint of glossiness due to the improvement of stability over time. Is particularly preferred.

The weight ratio of [water-insoluble organic compound / alkane polyol] is preferably from 3/1 to 1/5, more preferably from 1/1 to 1/5, and more preferably from 1/1 to 1/5, from the viewpoint of glossiness due to improved stability over time. 1/3 is particularly preferred.
The weight ratio of [water-insoluble organic compound / polymer particles] is preferably 1/50 to 1/1, more preferably 1/30 to 1/1, and more preferably 1/10 to 1/1, from the viewpoint of improving glossiness. Is particularly preferred.
The weight ratio of [water-insoluble organic compound / colorant] is preferably 1/40 to 5/1, and more preferably 1/30 to 1/1, from the viewpoint of gloss.
The weight ratio of [polymer particles / colorant] is preferably 10/90 to 75/25, more preferably 20/80 to 50/50, from the viewpoints of dispersion stability of polymer particles and printing density.

The water content in the water-based ink of the present invention is preferably 30 to 90% by weight, more preferably 40 to 80% by weight. The water dispersion is obtained by dispersing water with a colorant as a main solvent, and the water-based ink is ink using water as a main solvent.
The surface tension (25 ° C.) of the water-based ink for thermal inkjet recording of the present invention is preferably 20 to 35 mN / m, more preferably 25 to 35 mN / m, from the viewpoint of ensuring good ejection stability from the ink nozzle. It is. The surface tension (20 ° C.) as an aqueous dispersion for obtaining the aqueous ink of the present invention is preferably 30 to 65 mN / m, more preferably 35 to 60 mN / m.
The viscosity (20 ° C.) of the aqueous ink for thermal ink jet recording of the present invention is preferably 2 to 12 mPa · s, more preferably 2.5 to 10 mPa · s, in order to maintain good ejection stability. The viscosity (20 ° C.) of 10% by weight as an aqueous dispersion for obtaining the aqueous ink of the present invention is preferably 2 to 6 mPa · s in order to obtain a preferable viscosity when used as an aqueous ink. 5 mPa · s is more preferable.

In the following production examples, examples , reference examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified. The weight average molecular weight of the polymer was measured by the following method.
(1) Method for measuring weight average molecular weight of polymer As solvent, 60 mmol / L phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 50 mmol / L lithium bromide (anhydrous reagent manufactured by Kanto Chemical Co., Inc.) are contained. Gel chromatography using N, N-dimethylformamide (for high performance liquid chromatography manufactured by Kanto Chemical Co., Ltd.) [GPC apparatus manufactured by Tosoh Corporation (HLC-8120GPC), column manufactured by Tosoh Corporation (TSK-GEL, α) -M × 2), flow rate: 1 mL / min], using polystyrene as a standard substance.

Production Example 1 (Production of polymer)
In the reaction vessel, 20 parts of methyl ethyl ketone (reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol: manufactured by Wako Pure Chemical Industries, Ltd.), column of Production Example 1 in Table 1 10% of each monomer shown in the above was added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.
On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into a dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator (2,2′-azobis (2,4-dimethyl) were added. Valeronitrile: V-65) manufactured by Wako Pure Chemical Industries, Ltd.) 1.2 parts were added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.
Under a nitrogen atmosphere, the temperature of the mixed solution in the reaction vessel was increased to 65 ° C. while stirring, and then the mixed solution in the dropping funnel was gradually dropped over 3 hours. After stirring for 2 hours at 65 ° C. after the completion of dropping, a solution in which 0.3 part of the radical polymerization initiator was dissolved in 5 parts of methyl ethyl ketone was added, and stirring was further continued at 65 ° C. for 2 hours, and further aged at 70 ° C. for 2 hours. To obtain a polymer solution (polymer solution I). The weight average molecular weight of the obtained polymer was measured by the method shown above. The results are shown in Table 1.

Production Examples 2 and 3 (Production of polymer)
In the same manner as in Production Example 1 except that the monomers described in Production Examples 2 and 3 in Table 1 were used in place of the monomers described in Production Example 1 in Table 1, Polymer Solution II and Polymer Solution III was prepared.

The details of the compounds shown in Table 1 are as follows.
(A) Methacrylic acid: Reagent manufactured by Wako Pure Chemical Industries, Ltd. (b) Styrene macromer: manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy Base solid concentration 50%
(C) Benzyl methacrylate: Reagent manufactured by Wako Pure Chemical Industries, Ltd. (d) EH-4E: Polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added = 4, terminal: 2-ethylhexyl group): Shin-Nakamura Chemical Co., Ltd. Product name NK-Ester EH-4E
Styrene: Wako Pure Chemical Industries, Ltd.

Synthesis Example 1 (Synthesis of water-insoluble organic compound A)
In a reaction vessel, 100 parts of phthalic anhydride (reagent manufactured by Wako Pure Chemical Industries, Ltd.), 400 parts of 2-ethylhexyl alcohol ethylene oxide 4 mol adduct (manufactured by Nippon Emulsifier: New Coal 1004), and titanium tetraisopropoxide (Reagent manufactured by Wako Pure Chemical Industries, Ltd.) 0.5 parts was added and mixed, and after sufficient nitrogen gas replacement, the temperature was raised to 220 ° C. to carry out an esterification reaction. Furthermore, water generated by performing a reduced pressure reaction at 100 kPa at the same temperature was distilled off, and the esterification reaction was completed to obtain a phthalic acid diester-based water-insoluble organic compound A. The SP value of the water-insoluble organic compound A determined from the Fedors equation was 9.4.

Synthesis Example 2 (Synthesis of water-insoluble organic compound B)
In a reaction vessel, put 100 parts of trimellitic anhydride (a reagent manufactured by Wako Pure Chemical Industries, Ltd.), 462 parts of 4-ethylhexyl alcohol adduct of ethylene oxide, and 0.5 parts of titanium tetraisopropoxide. After mixing and sufficient nitrogen gas replacement, the temperature was raised to 220 ° C. to carry out an esterification reaction. Furthermore, water generated by performing a reduced pressure reaction at 100 kPa at the same temperature was distilled off, and the esterification reaction was completed to obtain trimellitic acid triester-based water-insoluble organic compound B. The SP value of the water-insoluble organic compound B determined from the Fedors equation was 9.7.

Production Example 4 (Production of aqueous dispersion of polymer particles containing pigment)
25 parts of the polymer obtained by drying the polymer solution I obtained in Production Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and a neutralizer (5N sodium hydroxide aqueous solution manufactured by Wako Pure Chemical Industries, Ltd. for volume analysis) was dissolved therein. 6.7 parts (neutralization degree: 75%) and 230 parts of ion-exchanged water were added to neutralize the salt-forming groups, and pigments (CI Pigment Yellow 74, Sanyo Dye Co., Ltd., trade name) : FY7413) 75 parts are added, and a peripheral speed of 15 m / cm is obtained using Picomill (dispersion medium: zirconia φ = 0.05 mm, temperature: 20 ° C., dispersion medium / dispersion weight ratio: 8/2) manufactured by Asada Iron Works The dispersion treatment was performed for 2 hours at s. The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 180 MPa.
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: Water of a pigment-containing polymer particle having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (manufactured by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Film Co., Ltd., and removing coarse particles. A dispersion was obtained.

Production Examples 5 to 6 (Production of aqueous dispersion of polymer particles containing pigment)
Instead of the polymer solution I obtained in Production Example 1, the polymer solution II obtained in Production Example 2 and the polymer solution III obtained in Production Example 3 were used, respectively. An aqueous dispersion of pigment-containing polymer particles having a solid content concentration of 20% was obtained.

Example 1
80 parts of an aqueous dispersion of pigment-containing polymer particles obtained in Production Example 4 and 2 parts of the water-insoluble organic compound A obtained in Synthesis Example 1 were mixed together, and an ultrasonic homogenizer US-300T (manufactured by Nippon Seiki Seisakusho Co., Ltd.). ) To obtain a water dispersion containing water-insoluble organic compound A and pigment-containing polymer particles. It was confirmed that the water-insoluble organic compound A was present in the polymer.
Furthermore, 41 parts of an aqueous dispersion containing the obtained water-insoluble organic compound A and pigment-containing polymer particles were mixed with 5 parts of 1,2-hexanediol (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and glycerin (Wako Pure Chemical Industries, Ltd.). 5 parts of polyethylene glycol (average addition mole number 10), Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., 2,4,7,9-tetramethyl-5-decyne-4,7-diol) 1 part of ethylene oxide 10 mol adduct) and 43 parts of ion-exchanged water were mixed. By filtering the obtained liquid mixture with a syringe having a capacity of 25 mL equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by FUJIFILM Corporation) to remove coarse particles. A water-based ink for inkjet recording was obtained. The SP value of 1,2-hexanediol determined from the above Fedors equation was 13.4.

Example 2
In Example 1, water-based inks shown in Table 2 were obtained in the same manner as in Example 1 except that the water-insoluble organic compound B obtained in Synthesis Example 2 was used instead of the water-insoluble organic compound A.

Example 3 and Comparative Example 4
In Example 1, instead of the aqueous dispersion of polymer particles containing the pigment obtained in Production Example 4, the aqueous dispersion of polymer particles containing the pigment obtained in Production Example 5 and Production Example 6, respectively, was used. A water-based ink shown in Table 2 was obtained in the same manner as in Example 1 except that.

Reference example 4
In Example 3, water-based inks shown in Table 2 were obtained in the same manner as in Example 3 except that 1,2-butanediol was used instead of 1,2-hexanediol. The SP value of 1,2-butanediol determined from the above Fedors equation was 14.8.

Reference Example 5
In Example 1, dibutyl phthalate (PH) (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of the water-insoluble organic compound A, and 1,2-butanediol was used instead of 1,2-hexanediol. Were the same as in Example 1 to obtain water-based inks shown in Table 2. The SP value of dibutyl phthalate obtained from the above Fedors equation was 10.4.

Comparative Examples 1-3
In Examples 1 and 2 and Reference Example 5, water-based inks shown in Table 2 were used in the same manner as in Examples 1 and 2 and Reference Example 5 except that 48 parts of ion-exchanged water was used without using alkane polyol. Obtained.

Next, with respect to the water-based inks obtained in Examples , Reference Examples, and Comparative Examples, the discharge stability and the change in gloss over time were evaluated by the following methods. The results are shown in Table 2.
(1) Evaluation of ejection stability After preparing the water-based inks obtained in the examples and comparative examples above, a water-based ink that has passed for 1 hour is replaced with a commercially available thermal ink jet printer (PIXUS iP3500 (trade name) manufactured by Canon Inc.). ), Solid printing was performed on inkjet photographic paper (Canon Photo Paper Glossy Gold (trade name) manufactured by Canon Inc.), and the printed state was observed, and evaluated according to the following criteria.
〔Evaluation criteria〕
A A uniform solid print on the entire surface without streaks (portions where ink is not printed) or unevenness (portions where ink is printed but the density is low) can be obtained.
B Solid prints with no streaks but with occurrence of unevenness are obtained.
C Solid print with streaks is obtained.

(2) Evaluation of change in gloss over time A water-based ink that had been prepared for 1 hour at room temperature and a water-based ink that had been allowed to stand at room temperature for 3 days were each a commercially available thermal ink jet printer (PIXUS iP3500 manufactured by Canon Inc.). Product name)), and solid-printed on inkjet photo paper (Canon Photo Paper Glossy Gold (product name) manufactured by Canon Inc.), left at 25 ° C for 24 hours, and then given a gloss of 20 ° An average value was obtained by measuring 5 times with a color industry, product name: HANDY GLOSSMETER, product number: PG-1.
The difference between the glossiness of the ink left at room temperature for 3 days and the glossiness of the ink after 1 hour of preparation was calculated according to the following formula and evaluated according to the following criteria.
[(Average value of glossiness of ink left at room temperature for 3 days) − (Average value of glossiness of ink after 1 hour of preparation)]
〔Evaluation criteria〕
A Difference in average value of glossiness is less than 5 B Difference in average value of glossiness is 5 or more and less than 10 C Difference in average value of glossiness is 10 or more

From Table 2, the aqueous inks of Examples 1 to 3 are excellent in ejection stability as compared with the aqueous inks of Comparative Examples 1 to 4, and the ink after 1 hour at room temperature and the ink after storage for 3 days at room temperature. It can be seen that there is little change in the glossiness when printed on special paper, and that the gloss is stable over time.

Claims (4)

(A) Polymer particles containing a colorant, (B) One or more water-insolubles selected from the group consisting of an ester compound and an ether compound having a maximum weight of 5 g or less that can be dissolved in 100 g of water (20 ° C.) An aqueous compound for thermal ink jet recording comprising an organic compound and (C) an alkane polyol having 4 to 12 carbon atoms, wherein the polymer is a structural unit derived from the salt-forming group-containing monomer (a), and (meth) Structural unit derived from acrylic ester-based macromer (b), structural unit derived from alkyl ester or aryl ester (c) of (meth) acrylic acid, and alkane of (meth) acrylic acid represented by the following general formula (1) essentially-than, said water-insoluble organic reduction from one or more constituent units selected from the group consisting diyl oxide esters (d) a constitutional unit derived from Objects and the absolute value of the difference between the solubility parameter of alkane polyols (SP value) is 4.0 or less, a thermal type ink jet recording water-based ink.
^{_{CH 2 = C (R 12)}} COO (R 13 O) q R 14 (1)
(In the formula, R ¹² represents a hydrogen atom or a methyl group, R ¹³ represents a hydrocarbon group having 2 or 3 carbon atoms, R ¹⁴ represents a hydrogen atom or a linear or branched hydrocarbon group having 1 to 22 carbon atoms, q represents the average number of moles added and is a number from 1 to 60.)   The aqueous ink for thermal ink jet recording according to claim 1, wherein the water-insoluble organic compound is an alkylene oxide adduct.   The thermal ink jet recording water-based ink according to claim 1, wherein the alkane polyol is 1,2-alkanediol. The water-insoluble organic compounds are contained in the polymer particles, according to claim 1 to 3 thermal method water-based ink for inkjet recording according to any one of.