JP2011189527A - Recording method using aqueous ink ejector and pretreatment liquid applicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method by which image density is raised, bleeding is suppressed, fixing deterioration is prevented and high productivity and high image quality can be obtained. <P>SOLUTION: Carboxyl group-containing resin particulates are made to contain a color material which is insoluble or hardly-soluble in water to form a resin emulsion and aqueous ink comprises at least the resin emulsion, an aqueous solvent and water. A recorder is constituted of an ejector of the aqueous ink and an applicator of a recording medium treatment solution (hereinafter referred to as a pretreatment solution) on a recording medium before ejection of the aqueous ink. In the recording method using the recorder, the pretreatment solution contains a water-soluble carbodiimide group-containing resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording method using a water-based ink discharge apparatus and a pretreatment liquid coating apparatus.

The ink jet recording technique is a technique in which ink is made into fine droplets by a pressure on-demand method or a charge control method and is attached to a recording medium such as paper according to image information.
Such an ink jet recording technique is suitably used for image forming apparatuses such as printers, facsimiles, and copying machines.
Inkjet recording technology allows images to be formed by directly attaching ink to a recording medium. Therefore, compared to indirect recording using a photoconductor such as electrophotographic recording, recording can be performed with a simple apparatus configuration. Further development is expected as a recording method.

In aqueous inkjet recording, color materials such as pigments and dyes are dispersed in a vehicle containing water as a main component to produce ink, and ink droplets are ejected from a so-called inkjet head to form an image on a recording medium. When the recording medium is paper, particularly uncoated paper such as fine paper or rough paper, the ink flows along the pulp fibers of the paper, and the ink penetrates and diffuses. For this reason, most of the color material penetrates into the inside of the paper, resulting in a decrease in image density or an increase in density on the back side of the paper (this is called image back-through).
Further, when a plurality of colors of ink are applied, the color material components remaining on the paper surface increase, and so-called fixing property is deteriorated. Furthermore, on the paper surface, the jaggy called feathering occurs along the pulp fiber. In addition, when ink droplets of the second color are deposited on the first color ink layer for forming a color image, if the first color ink is insufficiently dried, the second color ink flows and is called color bleeding. There is also the possibility of blurring and a noticeable graininess.

Therefore, as described in Japanese Patent Application Laid-Open No. 2008-62503 of Patent Document 3, there is an example in which a pretreatment liquid component and an ink component are reacted to prevent density reduction, fixing reduction, and bleeding.
This is because before the image is formed on the recording medium, that is, before the ink droplets adhere to the recording medium, a substance capable of aggregating the colorant particles in the ink is applied and after the image is formed on the recording medium, that is, the ink After the droplets adhere to the recording medium, the solid component and the solution component in the ink are separated by aggregation of the coloring material, the solution component penetrates into the recording medium, and the fluidity of the coloring material on the recording medium is lost. Is aimed at. By this phenomenon, the fall-through is prevented by the decrease in density, bleeding, and the same effect.

Alternatively, as described in Japanese Patent Application Publication No. 2008-536709 of Patent Document 2, two components that can undergo a crosslinking reaction (for example, an isocyanate crosslinking agent and an active hydrogen group-containing material) coexist in the ink component from the beginning, There is an example in which a cross-linking reaction is performed by adding energy, that is, the ink is fixed to prevent a decrease in density, a decrease in fixing, and bleeding.
This is because the two components that can undergo a crosslinking reaction in the ink component undergo a crosslinking reaction, whereby the solid component and the solution component in the ink are separated, and the solution component penetrates into the recording medium. As a result, the coloring material on the recording medium It aims to lose its liquidity. By this phenomenon, the density drop, the fixing drop, the blur, and the same effect can be prevented from see-through and beading.

Alternatively, as described in Japanese Patent Application Laid-Open No. 2007-331171 of Patent Document 1, a recording medium in which a pretreatment liquid component is applied in advance on the entire surface is used, and the applied crosslinking component and ink component are subjected to a crosslinking reaction. There is an example in which the toner is fixed to prevent a decrease in density, a decrease in fixing, and bleeding.
This is because before the image is formed on the recording medium, that is, before the ink droplets adhere to the recording medium, a substance capable of crosslinking reaction with the ink droplets is applied and after the image formation on the recording medium, that is, the ink liquid. After the droplets adhere to the recording medium, the solid component and the solution component in the ink are separated by a crosslinking reaction, and the solution component penetrates into the recording medium, aiming to lose the fluidity of the coloring material on the recording medium. It is what. By this phenomenon, the density drop, the fixing drop, the blur, and the same effect can be prevented from see-through and beading.

Thus, in order to lose the fluidity of the ink on the surface of the recording medium, it is desirable to separate the solid component and the solution component.
For example, as described in Patent Document 3, a method of aggregating the colorant on the recording medium is conceivable.
However, it is difficult to prevent a decrease in fixing even if the density can be reduced and bleeding can be improved only by agglomeration.
Further, as described in Patent Document 2, it is conceivable to cause a component in the ink to undergo a crosslinking reaction.
However, it is difficult to prevent a decrease in density and bleeding even though a reduction in fixing can be improved only by a crosslinking reaction.
Furthermore, as described in Patent Document 3, it is conceivable to cause a crosslinking reaction between the components of the pretreatment liquid and the components in the ink.
However, it is difficult to prevent a decrease in density and bleeding even if a reduction in fixing can be improved only by a crosslinking reaction. That is, it is necessary to separately add a component capable of aggregating the color material.
As a result, it is considered insufficient for the printing performance currently required for inkjet recording.
Also, if the fixing property is insufficient, ink transfer to the recording medium transport member, rollers, paper guide plate, etc. during the transport of the recording medium on the machine, and the retransfer of the transferred ink to the recording medium may occur. This may occur, which is a major obstacle to high-speed printing or double-sided printing. For this reason, high fixability, especially high-speed drying properties are desired, and the need for a high-speed inkjet printer equipped with a line head is much higher than that of a serial printer.

In the present invention, a carboxyl group, which is a colorant-containing resin-containing resin fine particle, and a pretreatment liquid containing a water-soluble carbodiimide group-containing resin undergo a crosslinking reaction to promote separation of the solvent from the solid content, The object is to increase the image density, suppress bleeding, and prevent a decrease in fixing by speeding up the penetration and decreasing the fluidity of the coloring material. That is, the coloring material that undergoes a crosslinking reaction with the water-soluble carbodiimide group-containing resin in the pretreatment liquid is a resin fine particle having a carboxyl group, so that the crosslinking reaction itself expresses a pigment aggregation effect and increases the image density, It is another object of the present invention to provide an ink jet recording method in which bleeding is suppressed by the same effect, a crosslinking reaction is directly performed with a color material, and a reduction in fixing is prevented.
Further, the NCN equivalent of the water-soluble carbodiimide group-containing resin contained in the pretreatment liquid described above (chemical formula amount per 1 mol of carbodiimide group) is 500 or less, and the carboxyl groups and carbodiimide of the carboxyl group-containing resin fine particles constituting the resin emulsion The purpose is to ensure the cross-linking reaction of the group reliably and effectively, to increase the concentration, to suppress the bleeding, and to prevent the fixing deterioration.
In addition, after applying the pretreatment liquid on the recording medium and discharging the water-based ink, the recording medium is overheated to ensure the cross-linking reaction between the carboxyl group and the carbodiimide group, and to increase the concentration and bleed. An object of the present invention is to provide an ink jet recording method that suppresses and prevents a decrease in fixing.
It is another object of the present invention to provide an ink jet recording method in which the ink jet recording method described above is developed on a so-called line head to which an ink jet head is fixed, and high productivity and image quality can be obtained.

The said subject is solved by following (1)-(4) of this invention.
(1) “A device for discharging a water-based ink containing at least a resin emulsion containing a water-insoluble or hardly-soluble colorant in a carboxyl group-containing resin fine particle, a water-soluble solvent, and water, and before discharging the water-based ink In a recording method using a recording apparatus comprising an apparatus for applying a recording medium processing liquid (hereinafter referred to as pretreatment liquid) onto a recording medium, the pretreatment liquid contains a water-soluble carbodiimide group-containing resin. Recording method",
(2) “The recording method according to (1) above, wherein the chemical formula amount per 1 mol of carbodiimide groups of the water-soluble carbodiimide group-containing resin contained in the pretreatment liquid is 500 or less”,
(3) The above-mentioned item (1) or (2), comprising the steps of applying a pretreatment liquid on a recording medium and discharging aqueous ink and then heating the recording medium to promote fixing. Recording method as described in section),
(4) In the above items (1) to (3), the apparatus for ejecting water-based ink is an ink jet system and the head is fixed, which is ink jet printing by a so-called line head. The recording method according to any one of the above.

According to the present invention, the carboxyl group of the colorant-containing resin-containing resin fine particles and the carbodiimide group of the water-soluble carbodiimide group-containing resin contained in the pretreatment liquid undergo a crosslinking reaction to promote separation of the solvent from the solid content. Accelerates permeation of the solvent into the recording medium, lowers the fluidity of the color material, and as a result, increases the image density, suppresses blurring, and prevents fixing deterioration. That is, since the coloring material that undergoes a crosslinking reaction with the water-soluble carbodiimide group-containing resin in the pretreatment liquid is a resin fine particle having a carboxyl group, the crosslinking reaction itself expresses a pigment aggregation effect to increase the image density, Furthermore, the same effect suppresses bleeding, and since the crosslinking reaction is performed directly with the colorant, the excellent effect of preventing a decrease in fixing is exhibited.
In addition, the NCN equivalent amount (chemical formula amount per 1 mol of carbodiimide groups) of the water-soluble carbodiimide group-containing resin contained in the pretreatment liquid is set to 500 or less, so that the carboxyl of the carboxyl group-containing resin fine particles constituting the resin emulsion An extremely excellent effect is exhibited in that the cross-linking reaction between the group and the carbodiimide group is ensured and effective, the image density is increased, the bleeding is suppressed, and the fixing is prevented from being lowered.
Furthermore, after applying the pretreatment liquid on the recording medium and discharging the water-based ink, the recording medium is overheated to ensure the cross-linking reaction between the carboxyl group and the carbodiimide group, and to increase the image density and blur. It is possible to suppress the deterioration of the toner image and to prevent a decrease in fixing.
Furthermore, the inkjet recording method is developed to a so-called line head in which the inkjet head is fixed, and high productivity and image quality are obtained.

It is the schematic which shows the internal structure of the droplet discharge apparatus used for continuous discharge property evaluation of this invention. It is the schematic which shows the internal structure of the heat fixing apparatus added to the prototype line head printer used for continuous discharge property evaluation of this invention. It is the schematic which shows another example for supplying a pre-processing liquid and ink to the to-be-printed medium of this invention.

[Carboxyl group-containing resin]
Hereinafter, the form for implementing this invention is demonstrated in detail and concretely.
In a preferred embodiment of the present invention, the pigment that can be used in the water-based ink is a resin emulsion in which a carboxyl group-containing resin fine particle contains a water-insoluble or hardly soluble color material, that is, a carboxyl group-modified polymer emulsion.
Here, “containing a color material” means either or both of a state in which a color material is enclosed in polymer fine particles and a state in which the color material is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary for all of the color material blended in the ink of the present invention to be encapsulated or adsorbed in the polymer fine particles, and the color material is dispersed in the emulsion as long as the effects of the present invention are not impaired. May be.

[Water-insoluble or poorly water-soluble colorant]
The color material is not particularly limited as long as it is water-insoluble or hardly water-soluble and can be adsorbed by the polymer.
In the present invention, water-insoluble or poorly water-soluble means that the coloring material does not dissolve 10 parts by weight or more with respect to 100 parts by weight of water at 20 ° C. This means that no separation or sedimentation is observed.
Examples of the coloring material include dyes such as oil-soluble dyes and disperse dyes, pigments, and the like.
Oil-soluble dyes and disperse dyes are preferable from the viewpoint of good adsorption and encapsulation, but pigments are preferably used from the light resistance of the obtained image.
In addition, the polymer used at this time has a structure of a carboxyl group, for example, polyacrylic acid, polymethacrylic acid, etc. are used, and the blending amount of the coloring material is related to the blending amount of the polymer. In this case, the amount is preferably about 10 to 200% by weight, particularly about 25 to 150% by weight, based on the weight of the polymer.
The blending amount of these carboxylic acid-modified pigments is 1 to 20 wt%, preferably 3 to 12 wt%, more preferably 5 to 10 wt%. Ink within this range is cross-linked by the carbodiimide group of the treatment liquid and aggregates and solidifies, and the color material remains on the paper surface. By this phenomenon, the density drop, the fixing drop, the blur, and the same effect can be prevented from see-through and beading.

More specifically, examples of pigments that can be contained in the carboxyl group-containing resin fine particles include organic pigments and inorganic pigments. For example, carbon blacks such as furnace black, lamp black, acetylene black, and channel black are used for black and white. (CI pigment black 7), or metals such as copper, iron (CI pigment black 11), titanium oxide, and organic pigments such as aniline black (CI pigment black 1). .
Further, for color use, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19 (quinacridone red), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 127 (bitumen ), 28 (cobalt blue), 29 (ultraviolet), 56, 60, 63, C.I. I. CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc., may be used in combination. Moreover, it is not limited to these.
These pigments may be used alone or in combination of two or more.
The blending amount of these pigments is 1 to 25 wt%, preferably 1 to 25 wt%, more preferably 5 to 15 wt% of the carboxyl group-containing pigment. The ink in this range can reliably and effectively cross-link with the carbodiimide group-containing water-soluble resin contained in the pretreatment liquid, increase the image density, suppress bleeding, and prevent fixing deterioration. .

[Water-soluble solvent]
In a preferred embodiment of the present invention, the water-soluble solvent that can be used in the water-based ink is a so-called water-soluble organic solvent.
For example, 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, glycerin, 1 , 3-butanediol, triethylene glycol, 1,6-hexanediol, propylene glycol, 1,5-pentanediol, diethylene glycol, dipropylene glycol, trimethylolpropane, trimethylolethane or ethylene glycol, 1,3-propanediol 1,4-butanediol, 2,3-butanediol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,2,6-hexanetriol, 1,2,4-butanetriol 1 Hydroxy compounds such as 2,3-butanetriol, thiodiglycol, pentaerythritol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene Polyhydric alcohol alkyl ethers such as glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolide, N-methyl-2-pyrrolidone, N-hydroxy Ethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-bu Nitrogen-containing heterocyclic compounds (lactams) such as rolactone; amides such as formamide, N-methylformamide, N, N-dimethylformamide; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol; propylene carbonate And ethylene carbonate.
Moreover, the compounding quantity of these water-soluble organic solvents is 10-50 wt%, You may mix and use.
Moreover, it is not limited to these.

[Other additives]
In the present invention, if necessary, the water-based ink may contain various materials conventionally used in ink jet recording inks.
For example, the surfactant is not particularly limited, but can be appropriately selected from surfactants that do not impair dispersion stability depending on the purpose, depending on the combination of the type of colorant, the wetting agent, the penetrating agent, and the like. However, particularly when printing on printing paper, those having low surface tension and high leveling properties are preferred, and at least one selected from silicone surfactants and fluorine surfactants is preferred. Among these, a fluorine-based surfactant is particularly preferable.

Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. The polyoxyalkylene ether polymer compound having a low foaming property is particularly preferable.
Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylate.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters and perfluoroalkyl phosphate salts.
Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers.
Examples of the counter ion of the salt in these fluorosurfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2 (CH2CH2OH) 2, NH (CH2CH2OH) 3, and the like.
As the fluorosurfactant, those appropriately selected may be used, or commercially available products may be used.
Examples of the commercially available products include Surflon series (S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145) manufactured by Asahi Glass Co., Ltd. Full Lard Series (FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431) manufactured by 3M, MegaFac Series manufactured by Dainippon Ink (F-470, F-1405, F-474, Dupont Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR), Neos FT-110, FT-250, FT-252, FT-400S, FT-150, FT-400SW, OM-nova PF-151N, etc. are mentioned, among these, good FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW and OMNOVA manufactured by Neos Co., Ltd. from the standpoint of significantly improving print quality, especially color development and leveling on paper. PF-151N is particularly preferred.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the purpose, and those that do not decompose even at high pH are preferable. For example, side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, piece Examples include terminal-modified polydimethylsiloxane and side-chain both-end-modified polydimethylsiloxane, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibit good properties as an aqueous surfactant. Particularly preferred.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used.
Such commercially available products can be easily obtained from, for example, Big Chemie, Shin-Etsu Silicone, Toray Dow Corning Silicone.
The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the dimethylpolysiloxane in the Si part. .
As said polyether modified silicone compound, what was synthesize | combined suitably may be used and a commercial item may be used.
As this commercial item, Shin-Etsu Chemical Co., Ltd. KF-618, KF-642, KF-643 etc. are mentioned, for example.
In addition to the fluorine-based surfactant and the silicone-based surfactant, anionic surfactants, nonionic surfactants, amphoteric surfactants, and the like can be used.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, succinate sulfonate, laurate, polyoxyethylene alkyl ether sulfate, and the like.
Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, , 5-dimethyl-1-hexyn-3-ol and the like.
Examples of the acetylene glycol surfactant include commercially available Surfynol series (104, 82, 465, 485, TG) manufactured by Air Products.
Examples of amphoteric surfactants include lauryl amino pyropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, stearyl dimethyl amine oxide, dihydroethyl lauryl amine oxide, Polyoxyethylene coconut oil alkyldimethylamine oxide, dimethylalkyl (coconut) betaine, dimethyl lauryl betaine and the like can be mentioned.
As such surfactants, commercially available products such as Nikko Chemicals, Nihon Emulsion, Nippon Shokubai, Toho Chemical, Kao, Adeka, Lion, Aoki Yushi, Sanyo Kasei, etc. Is available.
The surfactant is not limited to these, and may be used alone or in combination. Even if it does not easily dissolve in the ink for recording alone, it can be solubilized by mixing and exist stably.

  The content of the surfactant in the recording ink is preferably 0.01% by mass to 3% by mass, and more preferably 0.5% by mass to 2% by mass. However, the total content of the liquid components that are liquid in the ink at 25 ° C. having a boiling point higher than that of water is 20% by mass or less, and preferably 15% by mass or less. When the content is less than 0.01% by mass, the effect of adding the surfactant may be lost. When the content exceeds 3% by mass, the permeability to the recording medium becomes higher than necessary, and the image density decreases. There may be a show-through.

[Resin emulsion]
For example, a resin emulsion, the resin emulsion means an emulsion in which the continuous phase is water and the dispersed phase is the following resin component.
The resin emulsion has the property of thickening and aggregating, has the effect of suppressing the penetration of the coloring components, and further promoting the fixing to the recording material.
In addition, depending on the type of resin emulsion, a film is formed on the recording material, which has the effect of improving the abrasion resistance of the printed matter. Examples of the resin component in the dispersed phase include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, and styrene resins.
This resin is preferably a polymer having both a hydrophilic part and a hydrophobic part.
The particle size of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm.
These resin emulsions can be obtained by mixing resin particles in water, optionally with a surfactant.
For example, an acrylic resin or styrene-acrylic resin emulsion can be obtained by adding (meth) acrylic acid ester or styrene, (meth) acrylic acid ester, and optionally (meth) acrylic acid ester, and a surfactant to water. It can be obtained by mixing.
The mixing ratio of the resin component and the surfactant is usually preferably about 10: 1 to 5: 1.
When the amount of the surfactant used is less than the above range, it is difficult to form an emulsion, and when it exceeds the above range, the water resistance of the ink tends to be lowered or the penetrability tends to deteriorate.

The ratio of the resin as the dispersed phase component of the emulsion and water is 60 to 400 parts by weight, preferably 100 to 200 parts by weight with respect to 100 parts by weight of the resin.
Commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden Chemical Co., Ltd.) Company-made).

[PH adjuster]
For example, a composite material used in the present invention, which is a pH adjuster, has a strong tendency to show acidity when kneaded and dispersed in water together with an anionic dispersant.
The surface of the composite pigment particles dispersed in a medium such as water is negatively charged because it is encapsulated in an anionic dispersant. However, since the entire ink is acidic, the medium itself has a positive charge. It is in a state where the negative charge on the particle surface is easily neutralized. In this state, the dispersed particles agglomerate and cause ejection failure. Therefore, the dispersion state is stabilized by adding a pH adjuster and kept alkaline, and ejection can be stabilized.
The pH of the recording ink is preferably 7 or more and less than 11. When the pH is 11 or more, the amount of the material of the ink jet head or ink supply unit that is melted is large, and problems such as ink deterioration, leakage, and ejection failure occur.
It is more preferable to add the pH adjuster when the pigment is kneaded and dispersed in water together with the dispersant than with a kneading and dispersing machine, a wetting agent, a penetrating agent and the like. This is because the dispersion may be destroyed by adding some pH adjusters.
Examples of the pH adjuster include alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, and alkali metal carbonates.
Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

[Antiseptic and antifungal agent]
For example, antiseptic / antifungal agents such as sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, 1,2benzisothiazolin-3-one, etc. used in the present invention it can.
Examples of rust preventives include acidic sulfites, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole.

[Other additives]
In addition, a metal ion sealing agent, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, and the like can be added depending on the purpose.

[Pretreatment liquid and water-soluble carbodiimide group-containing resin]
In a preferred embodiment of the present invention, the water-soluble carbodiimide group-containing resin that can be used in the pretreatment liquid is a water-soluble resin having a crosslinking reactivity with a carboxyl group represented by the following formula (1), that is, a carbodiimide group-containing resin. is there. More desirably, the chemical formula amount per 1 mol of carbodiimide groups of the water-soluble carbodiimide group-containing resin is 500 or less.
As a water-soluble carbodiimide group-containing resin having a chemical formula amount per mol of commercially available carbodiimide group of 500 or less, carbodilite SV-02 (chemical formula amount per mol of carbodiimide group: 429, manufactured by Nisshinbo Chemical Co., Ltd.), carbodilite V-02- L2 (chemical formula amount per mol of carbodiimide group: 385, manufactured by Nisshinbo Chemical Co., Ltd.), carbodilite V-04 (chemical formula amount per mol of carbodiimide group: 335, manufactured by Nisshinbo Chemical Co., Ltd.), and the like.

[Other additives for pretreatment liquid]
In the present invention, various materials conventionally used in pretreatment liquids for ink jet recording can be included in the pretreatment liquid as necessary.
For example, a surfactant is added for two purposes: to lower the surface tension of the pretreatment liquid and to foam the pretreatment liquid.
In general, when a liquid pretreatment liquid is simply applied to a recording medium or other medium having an uneven surface by using an application roller or the like, the thickness of the pretreatment liquid on the surface of the application roller needs to be extremely thin. However, in that case, in the contact between the surface of the coating roller and the recording medium having the unevenness, the contact property is not good, and a portion where the pretreatment liquid cannot be applied is generated. Conversely, if the film thickness of the pretreatment liquid on the surface of the coating roller is increased in order to apply the pretreatment liquid to all recording media having irregularities, the pretreatment liquid more than necessary is applied to the recording medium, resulting in a cost reduction. Depending on the solvent type in the pretreatment liquid, the recording medium may be curled. Therefore, in the present invention, a method of applying the pretreatment liquid in the form of foam in advance before applying the pretreatment liquid to the recording medium is adopted.

There are no particular limitations on the surfactant used in the pretreatment liquid, and known ones can be used.
Examples thereof include silicone surfactants, fluorine surfactants, acetylene glycol surfactants, and the like. These may be used alone or in combination of two or more.
The addition amount of the surfactant is preferably 0.01% by mass to 3% by mass and more preferably 0.5% by mass to 2% by mass with respect to the pretreatment liquid.

  In addition to the pretreatment liquid, water or a volatile water-soluble solvent is added as a solvent. These may be used alone or in combination. However, when water is used alone as a solvent, curling may remarkably occur depending on the type of recording medium. On the other hand, when a volatile water-soluble solvent is used alone, the solvent will rapidly volatilize on the recording medium. Will not spread and will cause problems with filling. Therefore, it may be appropriately selected in consideration of usage conditions and environment.

[Discharging device for ink and pretreatment liquid]
FIG. 1 is a schematic view showing the internal structure of a droplet discharge device used for continuous discharge property evaluation of the present invention.
In the image recording apparatus (a), the paper feed tray (1) has a pressure plate (2) and a paper feed rotating body (4) for feeding the recording paper (3) attached to the base (5). . The pressure plate (2) is rotatable about a rotation shaft (8) attached to the base (5), and is urged to the sheet feeding rotator (4) by the pressure plate spring (6).
In order to prevent double feeding of the recording paper (3), a separation pad (not shown) made of a material having a large coefficient of friction such as an artificial skin is provided at a portion of the pressure plate (2) facing the paper feeding rotating body (4). ) Is provided. Further, a release cam (not shown) for releasing the contact between the pressure plate (2) and the sheet feeding rotating body (4) is provided.
In the above configuration, the release cam pushes the pressure plate (2) down to a predetermined position in the standby state. As a result, the contact between the pressure plate (2) and the sheet feeding rotator (4) is released. In this state, when the driving force from the conveying roller (7) is transmitted to the sheet feeding rotating body (4) and the release cam by a gear or the like, the release cam moves away from the pressure plate (2) and the pressure plate (2) rises. The sheet feeding rotator (4) contacts the recording sheet (3).
The recording paper (3) is picked up with the rotation of the paper feeding rotator (4), starts feeding, and is separated one by one by a separation claw not shown. The sheet feeding rotator (4) rotates to feed the recording sheet (3) to the platen (10) via the conveyance guide (9).
The recording paper (3) passes between the conveyance guides (8) and (9) and is guided to the conveyance roller (7). By the conveyance roller (7) and the pinch roller (11), the recording paper (3) reaches the platen (10). Be transported. Thereafter, the drive state from the conveying roller (7) is cut off again in the standby state in which the contact between the recording sheet (3) and the sheet feeding rotator (4) is released.
The paper feed rotator (12) for manual paper feed feeds the recording paper (3) mounted on the manual feed tray (13) by the paper feed rotator (12) according to the recording command signal of the computer. It is conveyed to the roller (7).
The recording paper (3) conveyed to the platen (10) passes under a line head (14) known per se.
Here, the recording paper conveyance speed and the droplet discharge timing are based on signals controlled by an electric circuit (not shown), thereby forming a desired image.

FIG. 2 is a schematic diagram showing the internal structure of the heat fixing device added to the first prototype line head printing apparatus used in the continuous discharge evaluation of the present invention (later using the prototype apparatus shown in FIG. 3). In order to perform a faster fixing process, the fixing unit is provided with two fixing rollers.
In the figure, (A) is a fixing roller, (B) is a pressure roller, (C) is a medium to be printed, and (D) is an electrostatic conveyance belt.
When the printing medium is heated before printing, a heating and fixing device is installed at the position of the manual feed tray (13) of the prototype line head printing device of FIG. The print medium is heated and supplied to the transport roller (7) in FIG. 1 for printing.
When the printing medium is heated after printing, a heating and fixing device is installed at the positions of the paper discharge units (17), (18), and (19) of the prototype line head printing apparatus of FIG. The medium is supplied to the electrostatic conveyance belt (D), and the medium to be printed is heated and discharged.
The media to be printed was passed through this device twice for the first time for pre-treatment liquid ejection application and for the second time for ink ejection printing. In order to carry out the present invention, the line head (14) is provided in duplicate, and the first (upstream) line head (14) is used for discharging and applying the pretreatment liquid, and the second (downstream) line head (14). ) Can be easily used for ink ejection printing.

  FIG. 3 shows an example of a prototype device actually used for supplying the pretreatment liquid and ink to the print medium. In this example, a pretreatment liquid supply device (20) is provided in the middle of the recording paper conveyance path between the paper feed tray (1) and the line head (14), and the pretreatment liquid supply device (20) The pretreatment liquid in the pretreatment liquid tank (20e) is supplied via the pumping roller (20a), the counter roller (20b), and the coating amount regulating roller (20c), and is supplied to the print medium (3) as recording paper. The main difference is that an application roller (20d) for application is provided.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but these examples are for explaining the present invention and are not intended to limit the present invention. In addition, “part” in each example represents “part by mass”.

[Ink adjustment]
(I) Pigment: Unmodified pigment (surfactant-dispersed pigment) / carboxyl group-modified pigment (polymer emulsion comprising a polymer fine particle having a carboxyl group and a water-insoluble or hardly soluble colorant)
(Ii) Surfactant: Nonionic (iii) Water-soluble organic solvent: Polyoxypropylene diglyceryl ether, glycerin, 1,3-butanediol (iv) Water-soluble resin: N-isopropylacrylamide Copolymer of acrylic acid / polyvinyl alcohol (v) pure water (vi) pH adjuster ... organic amine (triethanolamine)
(Vii) Preservative (viii) Rust inhibitor The above (v) pure water, (iii) water-soluble organic solvent, (iv) water-soluble resin, (vii) preservative, and (viii) rust inhibitor will be described later. At the quantitative ratios shown in Table 1, charging, dispersion stirring with a dissolver (DISPERMAT-FE), and a resin dispersion are prepared.
In this resin dispersion, (i) a pigment and (ii) a surfactant are appropriately added at a ratio shown in Table 1, and when the pigment is an unmodified pigment, the dispersion is stirred with a bead mill (Ashizawa-Labstar). In the case of a carboxyl group-modified pigment, dispersion stirring was performed with a dissolver (DISPERMAT-FE), and a pigment dispersion was prepared.
This pigment dispersion was filtered through a 3 μm filter to obtain an ink for inkjet recording.

[Preparation of carboxyl group-modified pigment (polymer emulsion containing carboxyl group-containing polymer fine particles containing a water-insoluble or hardly soluble colorant)]
(A) Preparation of phthalocyanine pigment-containing polymer fine particle dispersion: A blue polymer fine particle dispersion was obtained by reexamining Preparation Example 3 of JP-A No. 2001-139849.
The average particle diameter (D50%) of the fine polymer particles measured by Microtrac UPA was 93 nm.
(B) Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion: Red-purple polymer fine particle dispersion in the same manner as the blue polymer fine particle dispersion except that the phthalocyanine pigment of (a) was changed to Pigment Red 122 Got.
The average particle diameter (D50%) of the polymer fine particles measured by Microtrac UPA was 127 nm.
(C) Preparation of monoazo yellow pigment-containing polymer fine particle dispersion: A yellow polymer fine particle dispersion was obtained in the same manner as the preparation of the polymer fine particle dispersion except that the phthalocyanine pigment of (a) was changed to Pigment Yellow 74. It was.
The average particle diameter (D50%) of the polymer fine particles measured by Microtrac UPA was 76 nm.
(D) Preparation of carbon black-containing polymer fine particle dispersion: Black polymer fine particle dispersion was the same as the above-mentioned polymer fine particle dispersion except that the phthalocyanine pigment (a) was changed to carbon black (Degussa FW100). Got the body.
The average particle size (D50%) of the polymer fine particles measured by Microtrac UPA was 104 nm.

[Pre-treatment solution adjustment]
(I) Surfactant: alkylpyrrolidone (N-octyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone), acetylene glycol surfactant (ii) water-soluble carbodiimide group-containing resin (iii) water-soluble organic Solvent: alkylalkanediol (3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, any one or mixture), 1,3-butanediol, glycerin (iv) pure water The materials of the above (i) to (iv) are mixed at a quantitative ratio described in Table 1 described later, and dispersed and stirred with a dissolver (DISPERMAT-FE) to prepare treatment liquids of Examples and Comparative Examples. Using the image recording apparatus shown in Fig. 3, the pretreatment liquid was applied to the recording paper at a linear velocity of 85 mm / s at an adhesion amount of 2.8 to 3.2 g / m ² and evaluated. (Reference: JP 2007-276387 A)
The blending ratio (% by weight) of each component is as shown in Tables 1 and 2.

[Example 1]

[Comparative Example 1]

[Comparative Example 2]

[Comparative Example 3]

[Example 2]

[Example 3]

[Example 4]

[Image density evaluation method]
Printer name: Prototype line head printer ... FIG.
With external fixing device ... FIG.
Media name: Ricoh Co., Ltd. TYPE6200 PPC paper printing conditions: Recording density 300 × 600 dpi, 100% duty, Mj21pl, 23 ° C./65%
Image density: “Solid” is printed. Evaluated by X-Rite 939, portable spectral density manufactured by X-Rite.
Fixing property: “Solid on each color” is printed. JISL0849-evaluated according to the dye fastness test method for friction. “Transition density to cotton” was evaluated on a five-point scale.
Smudge: Prints “single color 5 dot line”. QEA's “Personal IASTM” evaluates “edge ragedness” on a five-point scale.

[Viscosity Evaluation Method]
Viscometer: Viscosity was evaluated with a tuning fork type vibration viscometer, SV-10, manufactured by A & D.
Measurement conditions: 23 ° C
Viscosity after standing-standing condition: 2 g of ink is put into a glass bottle having an inner diameter of 20 mm and dried at 24 ° C. and 20% / 24 hr with the lid open.

[Comparative Example 1]
Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. As understood from Table 1, the pretreatment liquid used was the same formulation as in Example 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

[Comparative Example 2]
Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. The pretreatment liquid was also adjusted in the same manner as in Example 1 except that each material shown in Table 1 was used in a quantitative ratio as shown in Table 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

[Comparative Example 3]
Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. The pretreatment liquid was also adjusted in the same manner as in Example 1 except that each material shown in Table 1 was used in a quantitative ratio as shown in Table 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. The pretreatment liquid was also adjusted in the same manner as in Example 1 except that each material shown in Table 1 was used in a quantitative ratio as shown in Table 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. The pretreatment liquid was also adjusted in the same manner as in Example 1 except that each material shown in Table 1 was used in a quantitative ratio as shown in Table 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

Each color ink was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used in the quantitative ratio as shown in Table 1. The pretreatment liquid was also adjusted in the same manner as in Example 1 except that each material shown in Table 1 was used in a quantitative ratio as shown in Table 1.
These were evaluated in the same manner as in Example 1. The results are summarized in Table 1.

a image recording apparatus a rotating shaft 1 sheet feeding tray 2 pressure plate 3 recording paper 4 sheet feeding rotating body 5 base 6 pressure plate spring 7 conveying roller 8 rotating shaft 9 conveying guide 10 platen 11 pinch roller 12 sheet feeding rotating body 13 manual feed tray 14 line Head 17 Paper discharge unit 18 Paper discharge unit 19 Paper discharge unit 20 Pretreatment liquid supply device 20a Pumping roller 20b Counter roller 20c Application amount regulating roller 20d Application roller A Fixing roller B Pressure roller C Media to be printed D Electrostatic transport belt

JP 2007-331171 A Special table 2008-536709 gazette JP 2008-62503 A

Claims (4)

  A device for ejecting aqueous ink containing at least a resin emulsion containing a water-insoluble or hardly soluble colorant in carboxyl group-containing resin fine particles, a water-soluble solvent, and water, and a recording medium before ejecting the aqueous ink A recording method using a recording apparatus comprising an apparatus for applying a recording medium treatment liquid (hereinafter referred to as a pretreatment liquid), wherein the pretreatment liquid contains a water-soluble carbodiimide group-containing resin.   2. The recording method according to claim 1, wherein the amount of chemical formula per 1 mol of carbodiimide groups of the water-soluble carbodiimide group-containing resin contained in the pretreatment liquid is 500 or less.   3. The recording method according to claim 1, further comprising the steps of applying a pretreatment liquid onto the recording medium and discharging the aqueous ink, and then heating the recording medium to promote fixing.   The recording method according to any one of claims 1 to 3, wherein the apparatus for ejecting water-based ink is an ink-jet system, and is a so-called line head ink-jet printing in which a head is fixed.

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