JP2003238854A - Water-base pigment type ink composition for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-base pigment type ink composition for inkjet recording, having good performances as to all of dryability, long-term delivery stability, dispersion stability, quality of print, e.g. density of print, and the like. <P>SOLUTION: The water-base pigment type ink composition for inkjet recording contains a self-water-dispersible copolymer resin which is obtained by copolymerizing monomer components containing a carboxylated unsaturated monomer, at least 5 mass% of an unsaturated monomer having a 14-20C aliphatic hydrocarbon group, and at least 15 mass% of an unsaturated monomer having an aromatic ring and which has an acid value of 70-130 mg/KOH, a pigment, urea, glycerin, a basic compound, and water, wherein the content of urea is 0.1-15 mass% based on the whole ink composition and wherein the ratio of the content of the glycerin to that of the urea is (1:1) to (100:1), with the total of the urea and the glycerin added being 10-30 mass% based on the whole ink composition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous pigment type ink jet ink composition used for ink jet recording. More specifically, it has excellent long-term ejection stability, ejection responsiveness, and long-term storage stability.
The present invention relates to an aqueous pigment type inkjet ink composition having a good print density.

[0002]

2. Description of the Related Art In the field of ink jet recording liquids,
Improving the printing speed and quality, and the ejection stability and ejection response are very important issues. Most of the inkjet ink compositions currently on the market are of a type in which a dye is used as a colorant, but this type has good ejection stability and can maintain high printing density and high saturation. Are known. However, the weather resistance and water resistance are not sufficient, and there has recently been a demand for a shift to the pigment type.

Even pigment-based aqueous pigment-based ink jet ink compositions are desired to have color-forming properties similar to dyes, ink stability, ejection stability, drying properties, and high print density. As a pigment-type aqueous pigment-type inkjet ink composition, a composition comprising a pigment, an aqueous binder resin for finely dispersing the pigment, a humectant, a basic compound, and water has been proposed. However, the conventional pigment-type water-based pigment-type inkjet composition is not sufficient in terms of long-term ejection stability, ink stability, drying property, and print quality.

In order to solve these problems, Japanese Patent Laid-Open No. 06-145574 discloses a polymer obtained by polymerizing at least a monomer giving an aromatic functional group and a monomer giving a carboxyl group. Molecular compound (acid value 1 in the examples)
An aqueous pigment-based inkjet ink composition composed of 95 to 312 mgKOH / g of a polymer compound), water, a water-soluble organic solvent, a pigment, a basic compound, and urea is disclosed. This improves the dispersion stability of the ink, the ejection stability over a long period of time, the print quality, and the drying property to some extent, but the high-polymer compound with a high acid value described in the examples is used, so that sufficient printing is achieved. It has a problem that the concentration cannot be obtained. Further, in recent years, higher printing stability such as ejection stability, drying property, ink dispersion stability, and printing density has been demanded, and the conventional one is still insufficient.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a printing quality such as ink drying property, long-term ejection stability, ink dispersion stability, printing density, etc. which is required for an aqueous pigment type ink jet ink composition. It is an object of the present invention to provide an aqueous pigment-based inkjet ink composition having excellent performances such as all.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted various studies in order to solve such problems, and as a result, as a resin, a specific self-water dispersibility having an acid value of 70 to 130 mgKOH / g is obtained. The present invention has been accomplished by finding that the above problems can be easily solved by using a copolymer resin and containing urea and glycerin as a moisturizing agent in a specific ratio.

That is, the present invention comprises (1) 5% by mass or more of an unsaturated monomer having a carboxyl group, an unsaturated monomer having an aliphatic hydrocarbon group having 14 to 20 carbon atoms, and an aromatic ring. 70 to 130 mg / KOH obtained by copolymerizing a monomer component containing 15% by mass or more of an unsaturated monomer
A self-water-dispersible copolymer resin, a pigment, urea, glycerin, a basic compound, and an aqueous pigment-based inkjet ink composition containing water, wherein the amount of urea added is the total amount of the aqueous pigment-based inkjet ink composition. For 0.
1 to 15% by mass, the addition amount of glycerin and the addition amount of urea are in a ratio of 1: 1 to 100: 1, and the total addition amount of urea and glycerin is the total amount of the aqueous pigment-based inkjet ink composition. To 10 to 30% by mass with respect to the aqueous pigment-based inkjet ink composition.

The present invention also provides (2) the self-water-dispersible copolymer resin obtained by copolymerizing a monomer component containing 30% by mass or more of an unsaturated monomer having an aromatic ring. The composition for an aqueous pigment-based inkjet ink according to (1) above. Further, in the present invention, (3) the unsaturated monomer having an aromatic ring of the self-water-dispersible copolymer resin is a benzyl (meth) acrylate-based monomer or a benzyl (meth) acrylate-based monomer. The aqueous pigment-based inkjet ink composition according to (1) or (2) above, which comprises a monomer and a styrene monomer and / or a phenyl (meth) acrylate monomer.

In the present invention, (4) the self-water-dispersible copolymer resin is stearyl (meth) acrylate, (meth) acrylic acid, a styrene monomer and a benzyl (meth) acrylate monomer. The self-water-dispersible copolymer resin obtained by copolymerizing a monomer component containing a monomer (1)
To (3) relates to the aqueous pigment-based inkjet ink composition. The present invention also relates to (5) the aqueous pigment-based inkjet ink composition according to any one of (1) to (4), wherein the basic compound is a non-volatile basic compound.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
First, as the pigment used in the present invention, various inorganic pigments and organic pigments generally used in ink jet recording liquids and aqueous printing inks can be used. Specifically, as inorganic pigments, titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, ultramarine blue, dark blue, carbon black, graphite and other colored pigments (white, black and other achromatic color pigments are also organic pigments. Including), and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments and condensed polycyclic pigments. These may be used alone or in combination of two or more.

Next, the self-water-dispersible copolymer resin used in the present invention is an unsaturated monomer having a carboxyl group, and an unsaturated monomer having an aliphatic hydrocarbon having 14 to 20 carbon atoms as a hydrophobic group. 5 mass% or more of a saturated monomer with respect to all monomer components, and 15 mass% or more of an unsaturated monomer with an aromatic ring with respect to all monomer components, above all, an unsaturated monomer having an aromatic ring The amount of the body is 30% by mass or more based on all the monomer components, and the monomer component containing a polymerizable unsaturated monomer is acid value 70 to 130 mgKOH / g if necessary.
And is preferably in the form of a high sol in an aqueous medium.

The acid value of the self-water-dispersible copolymer resin is 7
If it is lower than 0 mgKOH / g, the ejection stability tends to decrease, and if the acid value is higher than 130 mgKOH / g, the print density tends to decrease. The number of carbon atoms is 1
When the proportion of the unsaturated monomer having 4 to 20 aliphatic hydrocarbons is less than 5% by mass, the pigment dispersibility decreases, and when the amount of the unsaturated monomer having an aromatic ring is less than 15% by mass, the self-water dispersibility is obtained. Copolymer resin cannot be obtained. As a preferred form of the monomer component in the present invention, the ratio of the unsaturated monomer having an aliphatic hydrocarbon having 14 to 20 carbon atoms is 10
It is 5% by mass or more and 0% by mass or less with respect to 0% by mass. Further, the ratio of the unsaturated monomer having an aromatic ring is preferably 30% by mass or more and 70% by mass or less based on 100% by mass of the monomer component. In the present invention, the acid value of the self-water-dispersible copolymer resin obtained by copolymerizing the monomer components is 70 to 13
The kind and content of the unsaturated monomer having a carboxyl group and the polymerizable unsaturated monomer used as necessary in the above-mentioned monomer component will be appropriately set so as to be 0 mgKOH / g. . These unsaturated monomers may be used alone or in combination of two or more.

The unsaturated monomer having a carboxyl group used for obtaining the self-water-dispersible copolymer resin in the present invention includes acrylic acid, methacrylic acid, (anhydrous) maleic acid, monomethyl maleate and maleic acid. Monoethyl, monobutyl maleate, monohexyl maleate,
8 to 13 carbon atoms such as monooctyl maleate, mono-2-ethylhexyl maleate and monolauryl maleate
A maleic acid monoester compound having an aliphatic hydrocarbon group; having an aliphatic hydrocarbon group having 14 to 20 carbon atoms such as monomyristyl maleate, monocetyl maleate, monostearyl maleate, monooleyl maleate, monoeicosyl maleate Maleic acid monoester compounds; maleic acid diester compounds such as diethyl maleate and dibutyl maleate; crotonic acid and its ester compound, itaconic acid and its ester compound, silaconic acid and its ester compound, and the like.

The unsaturated monomer having an aliphatic hydrocarbon having 14 to 20 carbon atoms used for obtaining the self-water-dispersible copolymer resin in the present invention has 14 to 20 carbon atoms.
Examples of the (meth) acrylic acid ester having an aliphatic hydrocarbon group, the maleic acid monoester compound having an aliphatic hydrocarbon group having 14 to 20 carbon atoms, and the like. Specific examples of the (meth) acrylic acid ester having an aliphatic hydrocarbon group having 14 to 20 carbon atoms include myristyl (meth) acrylate (having 14 carbon atoms in the aliphatic hydrocarbon group) and (meth).
Cetyl acrylate (C16 of aliphatic hydrocarbon group),
Stearyl (meth) acrylate (18 carbon atoms of aliphatic hydrocarbon group), oleyl (meth) acrylate (18 carbon atoms of aliphatic hydrocarbon group) Eicosyl acrylate (carbon number of aliphatic hydrocarbon group) 20) can be exemplified.

Examples of unsaturated monomers having an aromatic ring used in the present invention include styrene, α-methylstyrene, vinyltoluene, dimethylstyrene, ethylstyrene, isopropylstyrene, t-butylstyrene, chlorostyrene, dichlorostyrene, Styrene-based monomers such as bromostyrene and fluorostyrene, benzyl methacrylate,
Benzyl (meth) acrylate-based monomers such as benzyl acrylate and phenyl (meth) acrylate-based monomers such as phenyl methacrylate and phenyl acrylate can be used.

The polymerizable unsaturated monomer used in the present invention as required includes methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic. Butyl acid, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylic acid ester compound having an aliphatic hydrocarbon group having 1 to 13 carbon atoms such as lauryl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Examples thereof include (meth) acrylic acid ester compounds having a hydroxyalkyl group having 2 to 8 carbon atoms such as (meth) acrylic acid-3-hydroxypropyl; (meth) acrylamide; acrylonitrile; olefin compounds.

In the present invention, in order to obtain good pigment dispersibility and storage stability by the self-water-dispersible copolymer resin, or high printing density, the self-water-dispersible copolymer resin is used during the pigment dispersion treatment. It is adjusted so that it is in the form of hydrosol in the aqueous medium in the above formulation and in the final formulation of the aqueous pigment type ink jet ink composition is in the form of hizosol or emulsion. Self-water dispersibility means such a form.

With respect to the molecular weight of the self-water-dispersible copolymer resin, the higher the molecular weight, the higher the possibility of aggregation and precipitation. Therefore, the weight average molecular weight is 2,000 to 50,0.
It is preferably 00, more preferably from 5,000 to
It is about 30,000.

In the present invention, as the aromatic ring component,
Benzyl (meth) acrylate-based monomer or (meth)
Benzyl acrylate monomer and styrene monomer and /
Alternatively, a self-water-dispersible copolymer resin using a phenyl (meth) acrylate monomer is preferable. That is, it is preferable that the unsaturated monomer having an aromatic ring of the self-water-dispersible copolymer resin is such a monomer. More preferably, the self-water-dispersible copolymer resin is (meth)
A self-water-dispersible copolymer resin obtained by copolymerizing a monomer component containing stearyl acrylate, (meth) acrylic acid, a styrene monomer and a benzyl (meth) acrylate monomer. In particular, as the monomer component, stearyl (meth) acrylate, (meth) acrylic acid, a styrene-based monomer and a benzyl (meth) acrylate-based monomer as main components, The ratio of stearyl (meth) acrylate to 100% by mass of the monomer component is 5% by mass or more, preferably 5 to 30% by mass, and the styrene-based monomer and the (meth) acrylic are based on 100% by mass of all the monomer components. Acid number 70-130 mgKOH / g, weight average molecular weight 5,000-30, obtained by using those having a total proportion of acid benzylic monomers of 30% by mass or more, preferably 30-70% by mass. 00 self-water-dispersible copolymer resin is preferable because it becomes excellent balance.

Further, examples of the basic compound usable in the present invention include inorganic basic compounds such as ammonium hydroxide; organic basic compounds such as triethylamine, monoethanolamine, triethanolamine and triethylenediamine. . These may be used alone,
You may use 2 or more types together. Among them, a non-volatile amine-based basic compound is preferable from the viewpoint of drying property and ejection stability, and triethylenediamine is particularly preferable. The degree of neutralization of the basic compound with respect to the self-water-dispersible copolymer resin is preferably 100% or more. That is, in the present invention, it is preferable to appropriately set the content of the basic compound so that the degree of neutralization with respect to the acid value of the self-water-dispersible copolymer resin is 100% or more.

In the aqueous pigment type ink jet ink composition of the present invention, the amount of urea added is in the range of 0.1 to 15% by mass based on the total amount of the aqueous pigment type ink jet ink composition, and the amount of glycerin added. And the amount of urea added are in a ratio of 1: 1 to 100: 1, and the total amount of urea and glycerin added is in the range of 10 to 30% by mass with respect to the total amount of the aqueous pigment-based inkjet ink composition. That is, the self-water-dispersible copolymer resin so that the composition in the water-based pigment type ink composition for ink is such.
A pigment, urea, glycerin, a basic compound and water are blended.

If the proportion of urea added is smaller than the above, the effect of long-term ejection stability cannot be obtained, and if the proportion of urea added is larger than the above, urea may precipitate near the nozzle. In addition, in order to obtain ejection stability, a humectant such as (poly) alkylene glycol such as (poly) ethylene glycol or (poly) propylene glycol and its alkyl ethers is added, but the present invention is effective. Can't get

In the aqueous pigment type ink jet ink composition of the present invention, if necessary, lower alcohols such as methanol, ethanol and propanol; and (poly) alkylenes such as (poly) ethylene glycol and (poly) propylene glycol. It is also possible to add one or more water-miscible solvents such as glycol and its alkyl ethers. Further, various additives such as a surfactant, a viscosity modifier, an antifoaming agent and a film forming aid may be added.

The preferred embodiment of the method for producing the aqueous pigment type ink jet ink composition of the present invention will be described below. First, a self-water dispersible copolymer resin is dissolved in water and an aqueous medium composed of a basic compound to obtain a resin varnish for pigment dispersion.

Then, the obtained resin dispersion varnish for pigment dispersion is mixed with a pigment, and if necessary, a pigment dispersant, a viscosity adjusting diluent, etc., and then a wet circulation mill, bead mill, ball mill, sand mill, attritor, roll mill. , Agitator, Henschel mixer, colloid mill,
The meat is kneaded with various dispersers such as an ultrasonic homogenizer, an ultrahigh pressure homogenizer, and a pearl mill. In a water-based pigment type ink jet ink composition used as an ink jet recording liquid, it is necessary to disperse the pigment more finely than in a normal printing ink, and a wet circulation mill is particularly preferable as a disperser. At that time, the solid content of the self-water-dispersible copolymer resin necessary for dispersing the pigment is 10 to 400 parts by weight, preferably 10 to 200 parts by weight, relative to 100 parts by weight of the pigment.

Next, after the pigment dispersion step is completed, water, urea, glycerin and, if necessary, various additives such as the water-miscible solvent, the viscosity modifier, the defoaming agent and the film-forming aid are added. Addition to obtain the aqueous pigment type ink jet ink composition of the present invention. The self-water-dispersible copolymer resin must be stably maintained in the form of a hydrosol in the formulation of the pigment dispersion step and the final formulation of the aqueous pigment-type inkjet ink composition. Therefore, while observing the morphology of the resin in advance with the formulation excluding the pigment, the amount of water, basic compound, urea, glycerin, and other additives to be used can be determined experimentally, and the same formulation will be used thereafter. An aqueous pigment-based inkjet ink composition can be produced. At that time, the content of the pigment in the final formulation of the aqueous pigment-based inkjet ink composition is 0.5 to 30% by mass, and more preferably 1.0 to 100% by mass of the aqueous pigment-based inkjet ink composition. It is preferable to adjust the amount of each component used so as to be in the range of 10% by mass.

The resulting aqueous pigment type ink jet ink composition of the present invention improves the drying property by permeation drying. From this point, the surface tension of the system is 22 to 45 m.
It is preferably N / m. Further, the viscosity of the obtained aqueous pigment-based inkjet ink composition of the present invention is 1.0 to 20.0 mPas at ambient temperature during use.
When s is suitable and the viscosity is in this range, the ejection stability is good, and a printed image with little bleeding at high speed can be obtained.

The aqueous pigment type ink jet ink composition of the present invention can be suitably applied as an ink jet recording liquid. Such an inkjet recording liquid is
Although it is an aqueous system, it has good pigment dispersibility for a long time,
When printed on a permeable base material such as paper, the printing density can be maintained high even if the permeation drying property is increased. Further, the ejection stability and the ejection response for a long period are also good. Further, since the cohesive force of the film is strong, it has excellent effects such as good water resistance and abrasion resistance.

[0029]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In this example, "parts" and "%" represent "parts by weight" and "mass%" unless otherwise specified.

<Production Method of Copolymer Resin Solution> Production Example 1 A four-necked flask is equipped with a stirrer, a cooling pipe and a nitrogen gas introducing pipe.
180 parts of butyl acetate was charged and heated to 100 ° C., while introducing nitrogen gas, 15.3 parts of methacrylic acid, 20.0 parts of stearyl methacrylate, 15.0 parts of styrene, 49.7 parts of benzyl methacrylate, start A mixture of Kayaester O-50TL (7.2 parts) and butyl acetate (46 parts) was added dropwise as an agent over 1.5 hours, and copolymerization was further performed for 2 hours while maintaining the same temperature. Then, the solvent was distilled under reduced pressure. , Weight average molecular weight 10,000, acid value 100 mg KOH / g,
A solid styrene-benzyl methacrylate-acrylic copolymer resin having a glass transition temperature of 67 ° C. was obtained. 30 parts of this solid styrene-benzyl methacrylate-acrylic copolymer resin was added to 7.5 parts of triethylenediamine and 62.5 of water.
Part of the mixture solution was dissolved to obtain a styrene-benzyl methacrylate-acrylic copolymer solution (solid content 30%, copolymer resin solution No. 1). Kayaester O-50TL: t-b represented by the following formula
utylperoxy2-ethyl-hexanoa
te 50% toluene solution

[0031]

[Chemical 1]

Production Example 2 A four-necked flask was equipped with a stirrer, a cooling pipe, and a nitrogen gas introduction pipe,
Charge 180 parts of butyl acetate and heat to 100 ° C., while introducing nitrogen gas, 10.3 parts of acrylic acid, 20.0 parts of stearyl methacrylate, 15.0 parts of styrene, 54.7 parts of benzyl methacrylate, start A mixture of Kayaester O-50TL (7.2 parts) and butyl acetate (46 parts) was added dropwise as an agent over 1.5 hours, and copolymerization was further performed for 2 hours while maintaining the same temperature. Then, the solvent was distilled under reduced pressure. A solid styrene-benzyl methacrylate-acrylic copolymer resin having a weight average molecular weight of 10,000, an acid value of 80 mgKOH / g and a glass transition temperature of 61.6 ° C. was obtained. 30 parts of this solid styrene-benzyl methacrylate-acrylic copolymer resin was dissolved in a mixed solution of 6 parts of triethylenediamine and 64 parts of water to give styrene-benzyl methacrylate-
An acrylic copolymer solution (solid content 30%, copolymer resin solution No. 2) was obtained.

Production Example 3 A four-necked flask was equipped with a stirrer, a cooling pipe, and a nitrogen gas introduction pipe.
180 parts of butyl acetate was charged and heated to 100 ° C., while introducing nitrogen gas, 7.7 parts of acrylic acid, 22.6 parts of stearyl methacrylate, 15.0 parts of styrene, 54.7 parts of benzyl methacrylate, start As a drug, a mixture of Kayaester O-50TL (7.2 parts) and butyl acetate (46 parts) was added dropwise over 1.5 hours.
After copolymerization for a time, the solvent was distilled off under reduced pressure to obtain a solid styrene-benzyl methacrylate-acrylic copolymer resin having a weight average molecular weight of 10,000, an acid value of 60 mgKOH / g and a glass transition temperature of 59.8 ° C. Obtained. This solid styrene-benzyl methacrylate-acrylic copolymer resin 3
0 part was dissolved in a mixed solution of 4.5 parts of triethylenediamine and 65.5 parts of water to prepare a styrene-benzyl methacrylate-acrylic copolymer solution (solid content 30%, copolymer resin solution No. 3). ) Got.

Production Example 4 A four-necked flask was equipped with a stirrer, a cooling pipe, and a nitrogen gas introduction pipe,
180 parts of butyl acetate was charged and heated to 100 ° C., while introducing nitrogen gas, 23.0 parts of methacrylic acid, 18.0 parts of stearyl methacrylate, 12.3 parts of styrene, 49.7 parts of benzyl methacrylate, start A mixture of Kayaester O-50TL (7.2 parts) and butyl acetate (46 parts) was added dropwise as an agent over 1.5 hours, and copolymerization was further performed for 2 hours while maintaining the same temperature. Then, the solvent was distilled under reduced pressure. , Weight average molecular weight 10,000, acid value 150 mg KOH / g,
A solid styrene-benzyl methacrylate-acrylic copolymer resin having a glass transition temperature of 60.3 ° C. was obtained. 30 parts of this solid styrene-benzyl methacrylate-acrylic copolymer resin was added to 11.3 parts of triethylenediamine and 5 parts of water.
It was dissolved in a mixed solution of 8.7 parts to give a styrene-benzyl methacrylate-acrylic copolymer solution (solid content 30
%, Copolymer resin solution No. 4) was obtained.

Production Example 5 A four-necked flask was equipped with a stirrer, a cooling pipe, and a nitrogen gas introduction pipe.
180 parts of butyl acetate was charged and heated to 100 ° C., while introducing nitrogen gas, 15.3 parts of methacrylic acid, 20.0 parts of normal butyl methacrylate, 15.0 of styrene.
Parts, benzyl methacrylate 49.7 parts, Kayaester O-50TL as an initiator 7.2 parts and butyl acetate 46.
1 part of the mixture was added dropwise over 1.5 hours and copolymerized for 2 hours while maintaining the same temperature, and then the solvent was distilled off under reduced pressure to obtain a weight average molecular weight of 11,000 and an acid value of 100 mgKO.
A solid styrene-benzyl methacrylate-acrylic copolymer resin having H / g and a glass transition temperature of 63 ° C. was obtained. 30 parts of this solid styrene-benzyl methacrylate-acrylic copolymer resin was dissolved in a mixed solution of 7.5 parts of triethylenediamine and 62.5 parts of water to prepare an aqueous solution of styrene-benzyl methacrylate-acrylic copolymer. (Solid content 3
0%, copolymer resin solution No. 5) was obtained.

Examples 1 to 4 and Comparative Examples 1 to 9 <Preparation of pigment-containing meat-based ink> Copolymer resin varnish N
o. For each of 1 to 5, copolymer resin varnish 1
To 3.5 parts of water, 71.5 parts of water was added and mixed to prepare a copolymer resin varnish, 15 parts of a pigment (Printex 80, manufactured by Degussa) was further added, and the mixture was stirred and mixed, followed by kneading with a wet circulation mill. Meat and get the base ink.

<Preparation of Inkjet Recording Liquid> The base ink obtained by the above method, water, glycerin and urea were mixed with stirring so that the ratios shown in Table 1 were obtained, and the inks of Examples 1 to 4 and Comparative Examples 1 to 9 were prepared. An inkjet recording liquid (water-based pigment type inkjet ink composition) was obtained. In Table 1, in the water-based pigment type inkjet ink composition, the numerical value in each formulation means parts by weight.

<Evaluation of Performance of Inkjet Recording Liquid> Measurement of surface tension The surface tension of the inkjet recording liquids of Examples 1 to 4 and Comparative Examples 1 to 9 was measured using a surface tensiometer (HLV-ST type, manufactured by Kyowa Interface Science Co., Ltd.). The results are shown in Table 1. 2. Storage stability test The ink jet recording liquids of Examples 1 to 4 and Comparative Examples 1 to 9 were sampled in glass bottles, tightly stoppered, and stored for 10 days at 60 ° C. to observe the presence or absence of sediment, and based on the following criteria. The storage stability was evaluated. The results are shown in Table 1.

<Performance evaluation of printed matter> Printing Method of Inkjet Recording Liquid With respect to the inkjet recording liquids of Examples 1 to 4 and Comparative Examples 1 to 9, a commercially available inkjet printer (MJ-930) was used.
C, piezo type, manufactured by Seiko Epson)
It was printed on recording paper Xerox L (manufactured by Xerox Co.). 2. Evaluation Method of Printed Material and Evaluation Results Printed materials were evaluated by the following evaluation methods, and the results are shown in Table 1.
Shown in.・ Print density The density of the solid part of the print is Macbeth optical densitometer RT-918
(Manufactured by Gretab Macbeth Co.) and evaluated based on the following criteria. -Drying property Immediately after printing of the inkjet recording liquid, the drying property was evaluated based on the following criteria from the time until the recording liquid was not attached to the finger by touching the finger. -Discharging stability (recovery) The ink cartridge of the inkjet printer MJ-930 (manufactured by Seiko Epson Corp.) is filled with each of the aqueous pigment-based inkjet ink compositions of Examples 1 to 4 and Comparative Examples 1 to 9 and continuously for 10 minutes. After printing the alphanumeric characters, the printer was stopped, and it was left without cap for 2 weeks in an environment of 40 ° C. and 25% RH. After leaving, the alphanumeric characters were printed again, and the number of recovery operations required until the same printing as before leaving was obtained was examined. The results are shown in Table 1. Evaluation A: 0 to 2 times of return operation enables printing equivalent to the initial printing B: 3 to 5 times of recovery operation enables printing equivalent to initial printing C: 6 times or more returning operation enables printing equivalent to initial printing impossible

[0040]

[Table 1]

[0041]

EFFECTS OF THE INVENTION Since the aqueous pigment type ink jet ink composition of the present invention has the above-mentioned constitution, it has long-term ejection stability, ink drying property, ink stability,
The printing quality such as printing density is good, and it can be suitably applied as an inkjet recording liquid.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomohiro Kita             Sakata, 1-23-37, Edobori, Nishi-ku, Osaka             Inkus Co., Ltd. (72) Inventor Yuka Hashimoto             Sakata, 1-23-37, Edobori, Nishi-ku, Osaka             Inkus Co., Ltd. F-term (reference) 2C056 EA06 EA26 FC02                 2H086 BA59 BA60 BA62                 4J039 AD03 AD09 AD10 AD14 BA17                       BC07 BC33 BC35 BC37 BE01                       CA06 EA10 EA44 GA24

Claims (5)

[Claims] 1. An unsaturated monomer having a carboxyl group,
Obtained by copolymerizing a monomer component containing 5% by mass or more of an unsaturated monomer having an aliphatic hydrocarbon group having 14 to 20 carbon atoms and 15% by mass or more of an unsaturated monomer having an aromatic ring. A water-based pigment ink composition containing 70 to 130 mg / KOH of a self-water-dispersible copolymer resin, a pigment, urea, glycerin, a basic compound and water, wherein the amount of urea added is a water-based pigment type. The amount is in the range of 0.1 to 15 mass% with respect to the total amount of the ink composition for inkjet, and the addition amount of glycerin and the addition amount of urea are 1: 1.
In the ratio of ˜100: 1, the total amount of urea and glycerin added is in the range of 10 to 30% by mass with respect to the total amount of the aqueous pigment-based inkjet ink composition. . 2. The self-water-dispersible copolymer resin is obtained by copolymerizing a monomer component containing 30% by mass or more of an unsaturated monomer having an aromatic ring. The composition for an aqueous pigment-based inkjet ink according to claim 1. 3. The unsaturated monomer having an aromatic ring of the self-water-dispersible copolymer resin is a benzyl (meth) acrylate-based monomer or a benzyl (meth) acrylate-based monomer. The styrene-based monomer and / or the phenyl (meth) acrylate-based monomer, and the aqueous pigment-based inkjet ink composition according to claim 1 or 2. 4. A monomer containing the self-water-dispersible copolymer resin containing stearyl (meth) acrylate, (meth) acrylic acid, a styrene monomer and a benzyl (meth) acrylate monomer. The aqueous pigment-based inkjet ink composition according to any one of claims 1 to 3, which is a self-water-dispersible copolymer resin obtained by copolymerizing a body component. 5. The aqueous pigment-based inkjet ink composition according to claim 1, wherein the basic compound is a non-volatile basic compound.