JP5655553B2 - Water-based inkjet pigment ink - Google Patents

Description

  The present invention provides high-quality images free from white streaks, color unevenness, and intercolor bleeding on general printing paper, particularly coated paper, art paper, and other highly hydrophobic paper, and is stable in ejection from inkjet nozzles. The present invention relates to an aqueous inkjet pigment ink having excellent storage stability.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. According to this method, there is an advantage that not only the noise of the apparatus to be used is small and the operability is good, but also colorization is easy and plain paper can be used as a recording member. It is widely used as an output machine in offices and homes.
On the other hand, in industrial applications, use as an output machine for digital printing is expected due to improvements in inkjet technology, and water-based pigment inks are required from the viewpoints of the environment and the durability of printed materials.

In aqueous pigment ink, since the pigment is insoluble in water, in order to keep the pigment dispersed in the ink, the dispersion is stabilized by using a dispersion resin. (For example, see Patent Documents 1, 2, and 3).
In the case of an ink jet recording system, a high-boiling water-soluble solvent that is positioned as a humectant is included for the purpose of preventing the nozzle from drying.

General printing paper is coated paper with a coating layer for receiving oil-based ink on its surface, but the coating layer is hydrophobic, so the wettability and absorption capacity of aqueous ink are poor. Has characteristics. Therefore, when an aqueous pigment ink generally used for ink jet recording is used, there are problems such as low wettability and penetrability of the ink and white streaks and blurring in the image.
For this reason, it is necessary to improve wettability and permeability by using a high-boiling water-soluble solvent having high permeability in the ink.
However, the use of a highly permeable solvent may change the dissolution state of the dispersion resin that stabilizes the pigment dispersion state, and may significantly reduce the pigment dispersibility and storage stability.

JP-A 64-6074 JP-A 64-31881 JP-A-3-210373

The present invention provides high-quality images free from white streaks, color unevenness, and intercolor bleeding on general printing paper, particularly coated paper, art paper, and other highly hydrophobic paper, and is stable in ejection from inkjet nozzles. Another object of the present invention is to provide an aqueous inkjet pigment ink having excellent storage stability.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following water-based inkjet pigment ink, and have completed the present invention.
That is, the first invention relates to a pigment, a pigment dispersion resin, water, a water-soluble solvent, a hardly water-soluble solvent, an amino acid
In an inkjet pigment ink comprising an alcohol and a surfactant,
The slightly water-soluble solvent is a glycol ether,
The surfactant is an acetylene glycol surfactant polyalkoxylate ,
The amino alcohol is dimethylethanolamine, diethylethanolamine, mono
The present invention relates to an inkjet pigment ink that is one or more selected from the group consisting of methylethanolamine .

The second invention relates to the inkjet pigment ink according to the invention, wherein the slightly water-soluble glycol ether is contained in an amount of 0.2 to 5% by weight based on the ink.
In the third invention, the slightly water-soluble glycol ether is one or more selected from the group consisting of diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether, and ethylene glycol monohexyl ether. The present invention relates to an inkjet pigment ink according to any one of the above inventions.

The fourth invention relates to the inkjet pigment ink according to any one of the inventions, wherein the amino alcohol is contained in an amount of 0.1 to 2% by weight based on the ink .

Further, a fifth invention is the inkjet pigment according to any one of the above inventions, wherein the surfactant contains 0.1 to 2% by weight of the polyalkoxylate of the acetylene glycol surfactant, based on the ink. It relates to ink.
The sixth invention relates to the ink-jet pigment ink according to any one of the inventions described above containing water-dispersible resin fine particles.

The seventh invention relates to the ink-jet pigment ink according to any one of the above inventions, which contains a water-dispersible wax.
The eighth invention relates to a printed matter obtained by printing the inkjet pigment ink of the invention on a printing paper.
The ninth invention relates to a printed matter printed on a printing paper in which an ink-receiving layer made of a water-soluble resin or a water-dispersible resin having a carboxyl group and / or a sulfonic acid group is coated on a printing paper.

  According to the present invention, it is possible to obtain a high-quality image free from white streaks, color unevenness, and intercolor bleeding on general printing paper, particularly coated paper, art paper, and other highly hydrophobic paper. It is possible to provide an aqueous inkjet pigment ink that is excellent in stability and storage stability.

First, because of the ink of the present invention, it is possible to obtain a high-quality image free of white streaks, color unevenness, and inter-color bleeding on general printing paper, particularly coated paper, art paper, and other highly hydrophobic paper. Explains whether it is excellent in ejection stability and storage stability.
In order to obtain a high-quality image in ink jet printing, it is important that ink ejected from the nozzles form ink dots on the printing paper by appropriately spreading and drying in a short time. Ink-jet inks cannot discharge ink when the nozzles are dried, so a humectant, that is, a high-boiling water-soluble solvent is essential. However, when it contains a high-boiling water-soluble solvent, it can be applied to coated paper (paper coated about 20 g / m ^{2 on} one side) and art paper (paper coated about 40 g / m ^{2 on} one side), which are general printing paper. When printing, the wettability and penetrability are poor, and this may cause white streaks and color unevenness that are caused by the connection between the printed dots.

Therefore, it is important to improve the drying property by using a solvent having high wettability and permeability to paper. A poorly water-soluble glycol ether is the solvent. Slightly water-soluble glycol ethers have much lower ability to reduce static surface tension compared to commonly used solvents such as glycerin and 1,3-propanediol, and wet to hydrophobic coated printing paper. High permeability and permeability. Furthermore, the effect of lowering the dynamic surface tension of the ink, particularly the surface tension in a short life time of 10 ms or less is great, and it becomes possible to eliminate beading (white streaks in which dots are connected to each other). That is, by using a poorly water-soluble glycol ether, the drying property becomes high, problems such as printing unevenness are solved, and the printing property is excellent.
However, these solvents have a big problem of reducing the dispersibility of the pigment. The reason is not clear, but these solvents are more hydrophobic than glycerin and 1,3-propanediol, and the hydrophobicity of the solvent in the ink is higher, so the dispersion resin adsorbed on the pigment is It is thought that it becomes easy to desorb to a solvent, and dispersibility falls.
In particular, in the storage stability of ink, when these solvents are used, the viscosity tends to be greatly increased or separated.

  Therefore, the combined use of the polyalkoxylate which is an acetylene glycol surfactant can reduce the amount of the slightly water-soluble glycol ether used. Polyalkoxylate, an acetylene glycol surfactant, has an excellent ability to wet a hydrophobic substrate appropriately, but it is not enough, and combined use with a poorly water-soluble glycol ether improves print quality. It can be further enhanced.

In addition, aminoalcohol selectively swells the base paper coated with resin to receive oil-based ink, and the aminoalcohol selectively distributes the polar groups of the coating layer, thereby swelling the base material and causing ink dots to be formed. By fixing, it is considered that bleeding between colors and color unevenness are eliminated.
Due to these actions, the use of glycol ether, amino alcohol, which is a poorly water-soluble solvent, and polyalkoxylate, which is an acetylene glycol-based surfactant, makes it possible to use general printing paper, especially coated paper, art paper, etc., which has high hydrophobicity. A high-quality image free from white streaks on the paper, color unevenness, and intercolor bleeding can be obtained, and ink excellent in ejection stability and storage stability from the ink jet nozzle can be obtained.
The water-based inkjet pigment ink of the present invention (hereinafter referred to as water-based pigment ink or ink) will be described below with reference to preferred embodiments.

The poorly water-soluble glycol ether used in the present invention is used for the purpose of lowering the dynamic surface tension of the aqueous pigment ink and enhancing the wettability and penetrability to the printing paper.
Specific examples of the poorly water-soluble glycol ether include, for example, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol mono 2-ethylhexyl ether, diethylene glycol mono 2-ethylhexyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether , Ethylene glycol monobenzyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, propylene glycol monophenyl ether, diethylene glycol dibutyl ether, and one or more of these may be used in combination. Can be used.

Of these, diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether, and ethylene glycol monohexyl ether having a solubility parameter close to that of a water-soluble solvent are more preferable from the viewpoint of ink stability.
In the present invention, the content of the slightly water-soluble glycol ether is preferably 0.2 to 5% by weight, more preferably 0.5 to 2% by weight, based on the whole ink. If it is less than 0.2% by weight, ink wettability and penetrability will be insufficient, and when printing on printing paper, the ink dots will not spread sufficiently, causing white streaks and color unevenness, which may be a problem. is there. On the other hand, if it exceeds 5% by weight, the storage stability of the ink with time may be insufficient, which may cause a problem.

The amino alcohol used in the present invention fixes the ink dots of the aqueous pigment ink by selectively swelling the coating layer with the amino alcohol on the printing paper coated with the resin to receive the oil-based ink. It is used for the purpose of eliminating intercolor bleeding and color unevenness.
Specific examples of amino alcohol include, for example, monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, monomethylethanolamine, dimethylethanolamine, monoethylethanolamine, and diethylethanolamine. These can be used alone or in combination of two or more.

Among these, if the boiling point of amino alcohol is too high, the water resistance of the printed matter may become a problem. Use dimethylethanolamine, diethylethanolamine, or monomethylethanolamine with an appropriate boiling point that does not affect the ejection properties. Is more preferable.
In the present invention, the content of amino alcohol is preferably 0.1 to 2% by weight, more preferably 0.2 to 1% by weight, based on the entire ink. If the amount is less than 0.1% by weight, the ink permeability is insufficient, and when printing on printing paper, the ink dots are not sufficiently fixed, causing intercolor bleeding and color unevenness, which may be a problem. . On the other hand, if it exceeds 2% by weight, there may be a problem of poor ejection properties due to an increase in ink viscosity.

The polyalkoxylate of the acetylene glycol surfactant used in the present invention is used for the purpose of reducing the dynamic surface tension of the aqueous pigment ink and improving the wettability and penetrability to the printing paper.
Specific examples of the polyalkoxylate as the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3, and the like. 6-diol, or polyalkoxylate such as 3,5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol, and one or more of these may be used. Can be used in combination.
Among these, it is particularly preferable to use a polyethoxylate of 2,4,7,9-tetramethyl-5-decyne-4,7-diol. Polyalkoxylates of acetylene glycol surfactants are commercially available, for example, from Air Products and Chemicals Inc. Surfynol 420, 440, 465, 485 manufactured by Kawaken Fine Chemical Co., Ltd., acetylenol E40, E81, E100, E200, Nissin Chemical Industry Co., Ltd. Orphine E1004, E1010 may be mentioned.

  In the present invention, the content of the polyalkoxylate of the acetylene glycol surfactant is preferably from 0.1 to 2% by weight, more preferably from 0.3 to 1% by weight, based on the entire ink composition. If it is less than 0.1% by weight, ink wettability and penetrability will be insufficient, and when printing on printing paper, the ink dots will not spread sufficiently, causing white streaks and color unevenness, which may be a problem. is there. On the other hand, if it exceeds 2% by weight, there may be a problem of poor ejection properties due to an increase in ink viscosity.

  The aqueous pigment ink of the present invention comprises at least a pigment, a water-soluble solvent, and water in addition to the specific poorly water-soluble solvent, amines, and surfactant defined in the present invention described above. Hereinafter, each of these components will be described.

As the pigment contained in the aqueous pigment ink of the present invention, conventionally known pigments can be used.
Examples of the black pigment that can be used in the present invention include carbon black produced by a furnace method or a channel method. For example, these carbon blacks have a primary particle diameter of 11 to 40 mμm (nm), a specific surface area by the BET method of 50 to 400 m 2 / g, a volatile content of 0.5 to 10% by mass, and a pH value of 2 to 10 Those having the following characteristics are preferred. The following are mentioned as a commercial item which has such a characteristic. For example,
No. 33, 40, 45, 52, 900, 2200B, 2300, MA7, MA8, MCF88 (manufactured by Mitsubishi Chemical), RAVEN1255 (manufactured by Colombia), REGAL330R, 400R, 660R, MOGULL (manufactured by Cabot), Nipex 160IQ, There are Nipex 170IQ, Nipex 75, Printex 85, Printex 95, Printex 90, Printex 35, Printex U (manufactured by Degussa), and any of them can be preferably used.

As a yellow pigment that can be used in the present invention, for example,
C. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 55, 74, 81, 83, 109, 113, 128, 150, 151, 155, 183, and the like.
Examples of magenta pigments that can be used in the present invention include:
C. I. Pigment Red 5, 7, 12, 22, 23, 31, 48 (Ca), 48 (Mn), 49, 52, 53, 57 (Ca), 57: 1, 112, 122; quinacridone solid solution, 146, 147, 150 238, 269, C.I. I. PigmentViolet 19 etc. are mentioned.
Examples of cyan pigments that can be used in the present invention include:
C. I. Pigment Blue 1, 2, 3, 15: 3, 15: 4, 16, 22, C.I. I. VatBlue 4, 6 etc. are mentioned.

As the pigment that can be used in the present invention, pigments of colors other than those described above, self-dispersing pigments, and the like can also be used. These pigments can be used alone or in combination of two or more in each color ink.
The content of the pigment that can be used in the present invention is in the range of 1 to 20% by weight, more preferably 2 to 12% by weight in the aqueous pigment ink.

As the pigment dispersion resin contained in the aqueous pigment ink of the present invention, conventionally known ones can be used, but (meth) acrylic acid copolymers are generally used. This is because charge repulsion occurs between pigments in an aqueous solvent due to charge repulsion when the (meth) acrylic acid copolymer adsorbed on the pigment surface is ionized, and a stable pigment dispersion state can be maintained. Conceivable.
As water contained in the water-based pigment ink of the present invention, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions.

The water content that can be used in the present invention is 10 to 90% by weight, more preferably 30 to 80% by weight, based on the total weight of the ink.
As the water-soluble solvent contained in the aqueous pigment ink of the present invention, conventionally known solvents can be used.

As the water-soluble solvent that can be used in the present invention, from the viewpoint of moisture retention, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1 , 4-butanediol, 2,3-butanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2,3-hexanediol, 2, Examples include 4-hexanediol. In addition, from the viewpoint of wettability to printing paper, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, Examples include triethylene glycol monobutyl ether. These water-soluble solvents can be used alone or in combination of two or more in each color ink.
The content of the water-soluble organic solvent that can be used in the present invention is generally in the range of 3 to 60% by weight, more preferably in the range of 3 to 50% by weight, based on the total weight of the ink.

  Furthermore, the ink of the present invention preferably contains water-dispersible resin fine particles. By containing the water dispersible resin fine particles, the viscosity of the coated film can be improved without increasing the viscosity. Thereby, water resistance, solvent resistance, scratch resistance and the like are improved. Even if a water-soluble resin is added, the resistance can be expected to improve to some extent, but the viscosity tends to increase. In the case of inkjet ink, there is a certain range in the viscosity at which ink can be ejected from the nozzles, and if the viscosity is too high, it may not be possible to eject ink, so it is important to suppress an increase in viscosity.

The content of the water-dispersible resin fine particles as described above in the ink is a solid content in the range of 2 to 20% by mass, and more preferably in the range of 3 to 15% by mass with respect to the total weight of the ink.
Furthermore, the ink of the present invention preferably contains a water-dispersible wax. By containing the water dispersible wax, the resistance of the printed coating film can be improved without increasing the viscosity. Thereby, abrasion resistance improves.

Examples of the water-dispersible wax that can be used in the present invention include water dispersions of natural wax and synthetic wax. Natural waxes include petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum, or plant waxes such as carnauba wax, candelilla wax, rice wax, and wood wax, and also animal plant waxes such as lanolin, A beeswax can be mentioned. As the synthetic wax, polyethylene wax which is a synthetic hydrocarbon wax,
Examples include Fischer-Tropsch wax and the like, or modified wax-based paraffin wax derivatives, montan wax derivatives, microcrystalline wax derivatives, and the like. These water-dispersible waxes can be used alone or in combination of two or more in each color ink. Commercially available water-dispersible waxes include, for example, AF-41, AG-73 (HDPE), A-514 (LDPE), A-329, A-206 (microcrystalline), AD manufactured by Gifu Seratech Manufacturing Co., Ltd. -62 (paraffin), X-8512 (lanolin), XA-35 (amide resin), AF-20 (beeswax), XD-075 (carnauba), AQUACER 531 (HDPE) manufactured by Big Chemie Japan.
The content of the water-dispersible wax as described above in the ink is a solid content in the range of 0.2 to 5% by weight of the total weight of the ink, and more preferably in the range of 0.3 to 2% by weight. It is.

In addition to the above-described components, the ink of the present invention may be appropriately added with additives such as a surface conditioner, an antifoaming agent, and an antiseptic agent in order to obtain an ink having a desired physical property value as necessary. be able to. Examples of the amount of these additives added are in the range of 0.05 to 10% by weight, preferably in the range of 0.2 to 5% by weight, based on the total weight of the ink.
Examples of the method for producing the ink of the present invention comprising the above-described components include the following methods, but the present invention is not limited thereto. First, a pigment is added to an aqueous medium in which at least a pigment dispersion resin and water are mixed, and after mixing and stirring, dispersion processing is performed using a dispersion means described later, and centrifugation is performed as necessary. To obtain a desired pigment dispersion. Next, if necessary, a water-soluble solvent or an appropriately selected additive component as mentioned above is added to the pigment dispersion, followed by stirring, and if necessary, filtering to obtain the ink of the present invention. To do.

  In the ink production method of the present invention, as described above, a pigment dispersion obtained by carrying out a dispersion treatment is used for the preparation of the ink, but before the dispersion treatment carried out during the preparation of the pigment dispersion. It is effective to perform premixing. That is, premixing may be performed by adding a pigment to an aqueous medium in which at least a pigment dispersion resin and water are mixed. Such a premixing operation is preferable because it improves wettability of the pigment surface and promotes adsorption of the dispersant to the pigment surface.

The disperser used in the above-described pigment dispersion treatment may be any disperser that is generally used, and examples thereof include a ball mill, a roll mill, a sand mill, a bead mill, and a nanomizer. Among these, a bead mill is preferably used. Examples of such include a super mill, a sand grinder, an agitator mill, a glen mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).
Furthermore, in the pigment premixing and dispersion treatment described above, the pigment dispersion resin may be dissolved or dispersed only in water, or may be dissolved or dispersed in a mixed solvent of a water-soluble solvent and water.

  Since the ink of the present invention is for inkjet recording, it is preferable to use a pigment having an optimum particle size distribution. That is, in order to make it possible to suitably use an ink containing pigment particles in an ink jet recording method, it is preferable to use a pigment having an optimum particle size distribution in view of demands such as nozzle clogging resistance. Examples of a method for obtaining a pigment having a desired particle size distribution include the following methods. Reduce the size of the grinding media of the disperser as mentioned above, increase the filling rate of the grinding media, increase the processing time, classify with a filter or centrifuge after grinding, etc. There are methods such as a combination of these methods.

As the printing paper for printing the aqueous pigment ink of the present invention described above, known ones can be used. For example, high-quality paper, coated paper, art paper, cast paper, or synthetic paper can be used. The surface of the substrate may be a smooth surface, an uneven surface, or transparent, translucent, or opaque.
Further, two or more of these substrates may be bonded to each other. Furthermore, a peeling adhesive layer or the like may be provided on the opposite side of the printing surface, or an adhesive layer or the like may be provided on the printing surface after printing.
Furthermore, a printing paper in which an ink receiving layer made of a water-soluble resin having a carboxyl group and / or a sulfonic acid group or a water-dispersible resin is coated on the printing paper can be used. As a result, it is possible to obtain a higher quality image without white streaks, color unevenness, and intercolor bleeding, as compared with the case of printing directly on the printing paper. This is because the carboxyl group and / or sulfonic acid group of the ink receiving layer works preferentially on the wettability of the ink due to the interaction with the poorly water-soluble glycol ether and amino alcohol contained in the aqueous pigment ink of the present invention, and widens the ink dots. At the same time, it is considered that ink penetration can be promoted.

The ink receiving layer can be applied by a known method, for example, roll coater method, blade coater method, air knife coater method, gate roll coater method, bar coater method, size press method, spray coating method, or gravure coater method. And curtain coater method. The ink receiving layer may be provided on only one side of the paper or may be provided on both sides.
Further, the ink receiving layer forming coating agent can be filled in an ink cartridge of an ink jet printer, and printing can be performed by the ink jet method at the same time as or before the other color ink.

  Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, “part” represents “part by weight”, and “%” represents “% by weight”.

(Production example of pigment dispersion resin)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 93.4 parts of triethylene glycol monomethyl ether and replaced with nitrogen gas. The inside of the reaction vessel was heated to 110 ° C., and a mixture of 35.0 parts of lauryl methacrylate, 35.0 parts of styrene, 30.0 parts of acrylic acid, and 6.0 parts of V-601 (manufactured by Wako Pure Chemical Industries) was added for 2 hours. Over the course of the polymerization reaction. After completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 3 hours, and then 0.6 part of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the reaction was further continued at 110 ° C. for 1 hour. Obtained. The weight average molecular weight of the pigment dispersion resin 1 was about 16000.
Further, after cooling to room temperature, 37.1 parts of dimethylaminoethanol was added for neutralization. This is the amount that neutralizes 100% of acrylic acid. Further, 200 parts of water was added to make it aqueous. 1 g of this was sampled, heated and dried at 180 ° C. for 20 minutes to measure the non-volatile content, and water was added so that the non-volatile content of the previously aqueous resin solution was 20%. As a result, an aqueous solution having a non-volatile content of 20% of the pigment dispersion resin 1 was obtained.

(Production example of water-dispersible resin fine particles)
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 40 parts of ion exchange water and 0.2 part of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant. , 40 parts of 2-ethylhexyl acrylate, 50 parts of methyl methacrylate, 7 parts of styrene, 2 parts of dimethylacrylamide, 1 part of methacrylic acid, 53 parts of ion-exchanged water, and Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) An additional 1% of the pre-emulsion with 1.8 parts premixed was added. After raising the internal temperature to 60 ° C. and sufficiently purging with nitrogen, 10 parts of a 5% aqueous solution of potassium persulfate and 20 parts of a 1% aqueous solution of anhydrous sodium bisulfite were added to initiate polymerization. After maintaining the reaction system at 60 ° C. for 5 minutes, the remaining pre-emulsion, 5% aqueous solution of potassium persulfate, and 1% aqueous solution of anhydrous sodium bisulfite were maintained for 1.5 hours while maintaining the internal temperature at 60 ° C. The mixture was added dropwise and stirring was continued for 2 hours. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. Diethylaminoethanol was added to adjust the pH to 8.5, and the solid content was adjusted to 40% with ion exchange water to obtain an aqueous dispersion of water-dispersible resin fine particles 1. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

(Production example of pigment dispersion)
20 parts of Pigment Yellow 74, 42.9 parts of water-dispersed pigment dispersion resin 1 and 37.1 parts of water were charged into a mayonnaise bottle as a pigment, predispersed with a disper, and then 250 parts of 0.8 mm diameter zirconia beads. Was dispersed as a dispersion medium, and this dispersion was performed with a paint shaker to obtain a pigment dispersion. At this time, the ratio of the non-volatile component between the pigment and the pigment-dispersed resin 1 is pigment / dispersed resin (non-volatile component) = 7/3.

(Ink production example)
20 parts of the obtained pigment dispersion, 4 parts of diethylene glycol monohexyl ether, 0.5 part of dimethylethanolamine, and 1 part of Surfynol 465 (manufactured by Air Products and Chemicals Inc.) as a polyalkoxylate of an acetylene glycol surfactant. 30 parts of propylene glycol, 27.5 parts of water, 12.5 parts of an aqueous dispersion of water-dispersible resin fine particles 1, and 30% of AF-41 (manufactured by Gifu Serask Manufacturing Co., Ltd.) as a water-dispersible wax. Ink was prepared by mixing 3.3 parts of the aqueous dispersion and filtering through a 10 μm membrane filter. At this time, 4 parts of pigment, 1.7 parts of pigment-dispersed resin, 5 parts of water-dispersible resin fine particles, and 1 part of water-dispersible wax are contained in 100 parts of ink.

(Production example of coating agent for forming ink receiving layer)
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser, 136.2 parts of ion exchange water, 1.6 parts of a 24% aqueous solution of RA-9607 (manufactured by Nippon Emulsifier Co., Ltd.) as a surfactant, and 0.13 parts of sodium bicarbonate was added as a buffering agent. Separately, 0.5 parts of diallyl phthalate, 40 parts of methacrylic acid, 30 parts of ethyl acrylate, 29.5 parts of butyl acrylate, 80 parts of ion-exchanged water, and the above-mentioned surfactants An additional 5% of the pre-emulsion pre-mixed with 6.4 parts of a 24% aqueous solution of RA-9607 was added. After raising the internal temperature to 75 ° C. and sufficiently purging with nitrogen, 10% of 6 parts of a 5% aqueous solution of potassium persulfate was added to initiate polymerization. After maintaining the reaction system at 75 ° C. for 5 minutes, the remaining pre-emulsion and the remaining 5% aqueous solution of potassium persulfate are added dropwise over 2 hours while maintaining the internal temperature at 75 to 80 ° C., and stirring is further performed for 2 hours. Continued. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. A vinyl emulsion was obtained by adjusting the solid content to 30% with ion-exchanged water. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.
To 100 parts of the obtained vinyl emulsion, 200 parts of purified water was blended to prepare a coating agent 1 for forming an inkjet ink receiving layer having a solid content of 10%.

(Example of printing paper production)
The coating agent 1 for forming the ink-jet ink receiving layer is coated on a coated paper [Oji Paper Co., Ltd., OK Top Coat Plus] with a wire bar No. 2 and dried in a hot air oven at 60 ° C. for 2 minutes to prepare a printing paper 1 having an inkjet ink receiving layer laminated thereon.

(Production example of printed matter)
Ink was filled in a cartridge of an inkjet printer (Epson "PM-750C"), and coated paper (+ Oji Paper Co., Ltd. OK top coat, basis weight 104.7g / ^{m 2)} and a pattern is printed on the printing paper 1 A printed matter for evaluation was produced.

(Examples 1-4)
According to the composition described in Table 1, a dispersion, an ink, and a printed matter for evaluation were prepared in the same manner as in the above production example.
(Comparative Examples 1-5)
According to the composition described in Table 2, a dispersion, an ink, and a printed matter for evaluation were prepared in the same manner as in the above production example.

  Table 3 shows the evaluation results of the storage stability of the ink over time, white streaks / color unevenness of the printed matter, and bleeding. A specific evaluation method will be described below.

(Ink storage stability over time)
After the ink was stored in a thermostat at 70 ° C. for 2 weeks and accelerated over time, changes in the viscosity, dispersed particle size, and filterability of the ink before and after aging were evaluated. When the change rate of viscosity and dispersed particle diameter before and after storage at 70 ° C. for 2 weeks was within ± 10%, it was evaluated as Δ when the change rate was within ± 10% or more and ± 20%, and × when it was ± 20% or more.

(White streaks / color unevenness of printed matter)
In a solid printing section with a printing rate of 100%, visually, white spots or white streaks appear to be x, white spots or white streaks appear to be Δ, white spots or white lines are Nothing was marked as ○. In particular, “A” indicates that there is no white spot or white streak and there is no density unevenness and a uniform solid print portion is obtained.

(Bleed of printed matter)
At the boundary where the single-color solid printing part with a printing rate of 100% is multiplied by different colors, visually, x is clearly blurred, Δ is slightly blurred, and there is no bleeding Was marked as ○. In particular, the case where a printed part having no blur was obtained even when three colors were overlaid was marked with ◎.

Claims (9)

In the pigment ink for inkjet, comprising a pigment, a pigment dispersion resin, water, a water-soluble solvent, a poorly water-soluble solvent, an amino alcohol, and a surfactant.
The slightly water-soluble solvent is a glycol ether,
The surfactant is an acetylene glycol surfactant polyalkoxylate ,
The amino alcohol is dimethylethanolamine, diethylethanolamine, mono
An ink-jet pigment ink that is one or more selected from the group consisting of methylethanolamine . The inkjet pigment ink according to claim 1, wherein the slightly water-soluble glycol ether is contained in an amount of 0.2 to 5% by weight based on the total weight of the ink. The inkjet according to claim 1 or 2, wherein the poorly water-soluble glycol ether is one or more selected from the group consisting of diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether, and ethylene glycol monohexyl ether. Pigment ink. The inkjet pigment ink according to any one of claims 1 to 3, wherein the amino alcohol is contained in an amount of 0.1 to 2% by weight based on the total weight of the ink. The inkjet pigment ink according to any one of claims 1 to 4 , wherein the polyalkoxylate of the acetylene glycol surfactant is contained in an amount of 0.1 to 2% by weight based on the total weight of the ink. The ink-jet pigment ink according to claim 1 , comprising water-dispersible resin fine particles. The ink-jet pigment ink according to any one of claims 1 to 6 , comprising a water-dispersible wax. A printed matter obtained by printing the inkjet pigment ink according to any one of claims 1 to 7 on a printing paper. A printing paper in which the ink-jet pigment ink according to any one of claims 1 to 7 is coated with an ink receiving layer made of a water-soluble resin having a carboxyl group and / or a sulfonic acid group and a water-dispersible resin on a printing paper. Printed material printed on.