JP2000290553A - Highly stable ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly stable ink composition and an ink composition which achieves high levels in various properties required clogging for ink compositions used for ink jet printing, such as stability against, discharge stability and shelf stability. SOLUTION: The ratio of a hydrophobic monomer-derived portion and a hydrophilic monomer-derived portion in a polymer constituting a resin emulsion, is adjusted to a specific range to obtain an extremely stable ink composition. The ink composition comprises a pigment, water, a water-soluble organic solvent and a resin emulsion particle. Here, the resin emulsion particle comprises at least a hydrophobic monomer-derived structure and a hydrophilic monomer- derived structure, wherein the amount of the hydrophilic monomer-derived structure is from 0.01 to 5 pts.wt. against 100 pts.wt. hydrophobic monomer- derived structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition having excellent stability and preferably used in an ink jet recording method.

2. Description of the Related Art An ink jet recording method is a printing method in which small droplets of ink are made to fly and adhere to a recording medium such as paper to perform printing. This method has a feature that high-resolution and high-quality images can be printed at a high speed with a relatively inexpensive apparatus.

Conventionally, an ink composition used for ink jet recording generally comprises a water-soluble dye or pigment, a water-soluble organic solvent, and water. One of the performances required for this ink is that an image with less bleeding can be realized. In particular, in multicolor printing, one color ink often comes into contact with another ink. The mixing or bleeding of two inks of different colors on the recording medium forms an undesired color, resulting in reduced image resolution, color separation, edge sharpness, and color purity. Therefore, an image with less blur can be realized.
This is an important performance required for the ink composition.

[0004] Recently, attempts have been made to use pigments as coloring materials. Pigments are excellent in water resistance and light resistance as compared with dyes, but are often pointed out to be inferior in scratch resistance because they remain as particles on a recording medium to form pixels. Further, since the pigment is essentially water-insoluble, it is necessary to stably disperse the pigment in the ink composition. For the stable dispersion of pigments, some additions of resins have been proposed. For example, JP-B-62-1426 discloses an ink in which a pigment and a resin emulsion are dispersed in water, and JP-A-55-157668 discloses that an ink is dispersed in a water-insoluble resin emulsion dispersion. Japanese Patent Application Laid-Open No. 1-217088 discloses that an emulsion having a specific film-forming temperature is used.
Japanese Patent Application Laid-Open No. HEI 4-18462 and JP-A-4-18462 similarly disclose an ink using a resin emulsion. Further, JP-A-56-147859 and JP-A-56-1
No. 47860 and Japanese Patent Publication No. 4-5703 propose an aqueous dispersion-based pigment ink using a polymer dispersant and a water-soluble organic solvent. Further, the pigment does not soak into the recording medium as in the case of the dye and is fixed, but is basically fixed and fixed to the surface of the recording medium, so that the abrasion resistance may be poor. In order to improve the fixability of the pigment, it has been proposed to add a resin component to the ink composition to firmly fix the pigment on the surface of the recording medium.

[0005]

SUMMARY OF THE INVENTION The present inventors have recently set the abundance ratio of a portion derived from a hydrophobic monomer and a portion derived from a hydrophilic monomer in a polymer constituting a resin emulsion within a specific range, It has been found that an ink composition having extremely excellent stability can be obtained. Accordingly, an object of the present invention is to provide an ink composition having excellent stability. Another object of the present invention is to provide an ink composition that realizes various characteristics required for an ink composition used in an ink jet recording method such as clogging stability, ejection stability, and storage stability at a high level. I have. The ink composition according to the present invention is an ink composition comprising a pigment, water, a water-soluble organic solvent, and resin emulsion particles, wherein the resin emulsion particles have a structure derived from a hydrophobic monomer. And at least a structure derived from a hydrophilic monomer, and 0.01 to 5 parts by weight of a structure derived from a hydrophilic monomer with respect to 100 parts by weight of a structure derived from a hydrophobic monomer. It is.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Ink Composition The ink composition according to the present invention is used in a recording method using the ink composition. Examples of the recording method using the ink composition include an ink jet recording method, a recording method using a writing instrument such as a pen, and various other printing methods. In particular, the ink composition according to the present invention is preferably used for an ink jet recording method.

[0007] The ink composition according to the present invention basically comprises
It comprises a pigment, water, a water-soluble organic solvent, and resin emulsion particles. The resin emulsion particles contain at least a structure derived from a hydrophobic monomer and a structure derived from a hydrophilic monomer, and are converted into a hydrophilic monomer based on 100 parts by weight of a structure derived from a hydrophobic monomer. And 0.01 to 5 parts by weight of the derived structure.

[0008] 2. Resin Emulsion Particles In the present invention, the resin emulsion particles include an abundance ratio of a portion derived from a hydrophobic monomer and a portion derived from a hydrophilic monomer. As a result, the ink composition has extremely excellent stability. The reason why this stability is developed is not clear, but because the hydrophobicity of the resin emulsion particles is high, the affinity with the pigment, especially the organic pigment, becomes high, and the colorant particles are stably formed in the ink composition. One of the reasons can be considered that it functions as a dispersing aid by surrounding. Further, in the ink composition according to the present invention, the presence of the resin emulsion is advantageous in that an image excellent in water resistance and abrasion resistance can be realized. That is, when the ink composition adheres to the recording medium and water and a water-soluble organic solvent near the resin emulsion particles penetrate into the recording medium and decrease, the resin emulsion particles coalesce and fuse together. To form a film containing the coloring material. Therefore, the obtained image has excellent abrasion resistance and excellent water resistance.

According to a preferred embodiment of the present invention, the particle size of the resin emulsion particles is preferably from 1 to 150 nm, more preferably from 10 to 100 nm.

The amount of the resin emulsion particles added to the ink composition is preferably about 0.1 to 10% by weight, more preferably 0.5 to 5% by weight.

In the present invention, the hydrophobic monomer has a polymerizable double bond and has a lipophilic hydrocarbon group, aromatic ring group or alicyclic group. Preferred specific examples thereof include methyl (meth) acrylate, ethyl (
(Meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate,
Isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) Vinyl esters such as acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate;
Acrylonitrile, methacrylonitrile, etc., styrene,
Aromatic vinyls such as 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene and divinylbenzene; vinylidene halides such as vinylidene chloride and vinylidene fluoride; ethylene, propylene and isopropylene , Butadiene, vinyl chloride, vinyl ether, vinyl ketone, chloroprene and the like.

The hydrophilic monomer includes a carboxyl group, a hydroxyl group, a hydroxymethyl group, an amino group, a sulfonic acid group, a polyethylene oxide group, a sulfate ester base, or a phosphoric acid group having a polymerizable double bond. It has an acid ester base. Preferred specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2
Acrylates or methacrylates such as hydroxypropyl (meth) acrylate, glycidyl methacrylate, glycidyl acrylate and vinyl esters such as vinyl acetate; vinylpyrrolidone; acrylic acid, methacrylic acid, maleic acid or a monoalkyl thereof containing a carboxyl group N-methylaminoethyl containing an amino group such as acrylamide having an amide group, N, N-dimethylacrylamide, etc .; ethylenically unsaturated carboxylic acids such as ester, itaconic acid or its monoalkyl ester, fumaric acid or its monoalkyl ester; Methacrylate, N-methylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethyl acrylate Alkylaminoesters of acrylic acid or methacrylic acid such as minoethyl methacrylate; N- (2-dimethylaminoethyl) acrylamide, N- (2-dimethylaminoethyl) methacrylamide, N, N-dimethylaminopropylacrylamide;
Unsaturated amides having an alkylamino group such as, for example, monovinylpyridines such as vinylpyridine, and vinylethers having an alkylamino group such as dimethylaminoethyl vinyl ether; vinylsulfonic acid, styrenesulfonic acid and salts thereof such as vinylimidazole , 2-acryloylamino-2-methylpropanesulfonic acid, and salts thereof having a sulfone group.

In the present invention, the resin emulsion particles are
For 100 parts by weight of a structure derived from a hydrophobic monomer,
0.01 to 5 parts by weight of a structure derived from a hydrophilic monomer, and more preferably, a structure derived from a hydrophilic monomer with respect to 100 parts by weight of a structure derived from the hydrophobic monomer. 0.1 to 3 parts by weight.

According to a preferred embodiment of the present invention, the resin emulsion preferably has a single particle structure. According to still another preferred embodiment, the resin emulsion preferably has a core-shell structure composed of a core portion and a shell layer surrounding the core portion.

According to a preferred embodiment of the present invention, the polymer constituting the resin emulsion preferably has a glass transition point of 30 ° C. or lower. By using such a polymer, the ink composition according to the present invention more reliably forms a film at normal temperature.

Further, according to a preferred embodiment of the present invention, the minimum film forming temperature of the resin emulsion is preferably 30 ° C. or lower. Here, the minimum film formation temperature refers to a temperature at which a transparent continuous film is formed when a resin emulsion is thinly cast on a metal plate such as aluminum and the temperature is increased. In a temperature region lower than the minimum film forming temperature, a white powder is formed. The temperature at this boundary is defined as the minimum film forming temperature. According to this aspect, it is possible to further improve the quick drying property, the touch property, the abrasion resistance, and the water resistance of the printed matter.

The resin emulsion used in the present invention can be produced by a suitable polymerization method, for example, emulsion polymerization of a hydrophobic monomer and a hydrophilic monomer in the presence of a polymerization catalyst and an emulsifier. Emulsifiers that can be used include anionic surfactants, nonionic surfactants, and mixtures thereof. Examples of anionic surfactants include alkyl sulfonates, alkyl sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylbenzene sulfonates, dialkyl sulfosuccinates, fatty acid salts, polyoxyethylene alkyl ether sulfates, and polyoxyethylene sulfonates. Ethylene phenyl ether sulfate and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene-polystyryl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, and polyoxyethylene. Fatty acid esters and polyglycerin fatty acid esters are exemplified. This emulsion polymerization is a preferred method for producing a resin emulsion in the form of a polymer emulsion. According to a preferred embodiment of the present invention, from the viewpoint of obtaining a stable polymer emulsion, its HLB
Of 15 to 20 surfactants is preferred.

As described above, the resin emulsion may have a single particle structure or a core-shell structure. Here, the resin emulsion having a core-shell structure is not particularly limited, but can be produced by a known method, generally by multi-stage emulsion polymerization or the like.

3. Pigment The coloring material contained in the ink composition according to the present invention is a pigment. As the pigment, an inorganic pigment or an organic pigment can be used. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, and a thermal method can be used. Examples of organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelated azo pigments, etc.) and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines) Pigments,
Thioindigo pigments, isoindolinone pigments, quinoflurone pigments, etc., dye chelates (eg, basic dye chelates, acidic dye chelates, etc.), nitro pigments, nitroso pigments, aniline black and the like can be used. In particular, as carbon black used as black ink, Mitsubishi Chemical No.2300, No.900, MCF88, No.33, No.40, No.45, N
o.52, MA7, MA8, MA100, No2200B, etc.
Raven5750, Raven5250, Raven5000, Raven3500, Raven125
5, Raven700 etc. are Regal 400R, Regal made by Cabot
330R, Rega l660R, Mogul L, Monarch700, Monarch 800, M
onarch 880, Monarch 900, Monarch 1000, Monarch 110
0, Monarch 1300, Monarch 1400, etc.
Color Black FW1, ColorBlack FW2, Color Black FW2V,
Color Black FW18, Color Black FW200, ColorBlack S
150, Color Black S160, Color Black S170, Printex 3
5, Printex U, Printex V, Printex 140U, Special Blac
k 6, Special Black 5, Special Black4A, Special Bla
ck 4 etc. can be used. Pigments used for yellow ink include CIPigment Yellow 1, CIPigment Y
ellow 2, CIPigment Yellow3, CIPigment Yellow 1
2, CIPigment Yellow 13, CIPigment Yellow 14C,
CIPigment Yellow 16, CIPigment Yellow 17, CI
Pigment Yellow 73, CIPigment Yellow 74, CIPigm
ent Yellow 75, CIPigment Yellow 83, CIPigment
Yellow 93, CIPigment Yellow95, CIPigment Yello
w97, CIPigment Yellow 98, CIPigment Yellow109,
CIPigment Yellow110, CIPigment Yellow114, C.
I. Pigment Yellow128, CIPigment Yellow129, CIPi
gment Yellow138, CIPigment Yellow150, CIPigmen
t Yellow151, CIPigment Yellow154, CIPigment Ye
llow180 and the like. Pigments used in magenta ink include CI Pigment Red 5, CI Pigment
Red 7, CIPigment Red 12, CIPigment Red 48 (C
a), CIPigment Red 48 (Mn), CIPigment Red 57 (Cn
a), CIPigment Red 57: 1, CIPigment Red 112, C.
I. Pigment Red 123, CIPigment Red 168, CIPigmen
t Red 184, CIPigment Red 202 and the like. CIPigm is a pigment used for cyan ink.
ent Blue 1, CIPigment Blue 2, CIPigment Blue
3, CIPigment Blue 15: 3, CIPigment Blue 15:34,
CIPigment Blue 16, CIPigment Blue 22, CIPigm
ent Blue 60, CIVat Blue 4, CIVat Blue 60 and the like. However, it is not limited to these.

The particle size of these pigments is preferably 10 μm or less, more preferably 0.1 μm or less.

According to a preferred embodiment of the present invention, these pigments are preferably added to the ink as a pigment dispersion obtained by dispersing in an aqueous medium with a dispersant or a surfactant. As a preferred dispersant, a dispersant commonly used for preparing a pigment dispersion, for example, a polymer dispersant can be used. It will be apparent to those skilled in the art that the dispersant and surfactant contained in this pigment dispersion will also function as the dispersant and surfactant of the ink composition. Preferred examples of the polymer dispersant include natural polymers, specific examples of which include glue, gelatin, casein, proteins such as albumin, gum arabic, natural gums such as tragacanth gum, glucosides such as savonin, Examples include alginic acid and alginic acid derivatives such as alginic acid propylene glycol ester, alginic acid triethanolamine and ammonium alginate, and cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose and ethylhydroxycellulose. Further, preferred examples of the polymer dispersant include synthetic polymers, polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, acrylate-acrylonitrile copolymer,
Acrylic resins such as vinyl acetate-acrylate copolymer, acrylic acid-acrylate copolymer,
Styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid -Styrene-acrylic resin such as acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, and Vinyl acetate-based copolymers such as vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, and vinyl acetate-acrylic acid copolymer And copolymers and salts thereof. Among them, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group in a molecular structure are preferable.

The content of the pigment in the ink composition of the present invention is preferably about 0.5 to 25% by weight, and more preferably about 2 to 15% by weight.

4. Water-Soluble Organic Solvent Also, the ink composition according to the present invention comprises a water-soluble organic solvent. The water-soluble organic solvent is preferably a low-boiling organic solvent, and examples thereof include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, sec-butanol and tert.
-Butanol, iso-butanol, n-pentanol and the like. Particularly, a monohydric alcohol is preferable. Low-boiling organic solvents have the effect of shortening the drying time of the ink. The amount of the low boiling organic solvent added is preferably 0.1 to 30% by weight of the ink, more preferably 5 to 10% by weight.

According to a preferred embodiment of the present invention, the ink composition used in the present invention preferably further comprises a wetting agent comprising a high-boiling organic solvent. Preferred examples of the high-boiling organic solvent include ethylene glycol,
Diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-
Polyhydric alcohols such as hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, Alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2 -Imidazolidinones and the like.

The amount of the wetting agent added is 0.1% of the ink.
It is preferably in the range of 1 to 30% by weight, more preferably 1 to 15% by weight.

According to a preferred embodiment of the present invention, when the glass transition point of the resin emulsion is 30 ° C. or less or the minimum film forming temperature of the polymer emulsion is 30 ° C. or less, the use of a water-soluble organic solvent having a boiling point of 180 ° C. or more is preferred. preferable. Preferred examples of the water-soluble organic solvent include ethylene glycol (boiling point: 197 ° C .;
Propylene glycol (187 ° C), diethylene glycol (245 ° C), pentamethylene glycol (242
° C), trimethylene glycol (214 ° C), 2-butene-1,4-diol (235 ° C), 2-ethyl-1,
3-hexanediol (243 ° C), 2-methyl-2,
4-pentanediol (197 ° C), N-methyl-2-
Pyrrolidone (202 ° C), 1,3-dimethyl-2-imidazolidinone (257-260 ° C), 2-pyrrolidone (245 ° C), glycerin (290 ° C), tripropylene glycol monomethyl ether (243 ° C), dipropylene Glycol monoethyl glycol (198 ° C.),
Dipropylene glycol monomethyl ether (190
° C), dipropylene glycol (232 ° C), triethylene glycol monomethyl ether (249 ° C), tetraethylene glycol (327 ° C), triethylene glycol (288 ° C), diethylene glycol monobutyl ether (230 ° C), diethylene glycol monoethyl ether (202 ° C.), diethylene glycol monomethyl ether (194 ° C.) and the like. According to a preferred embodiment of the present invention, as a high boiling water-soluble solvent, for example,
Ethylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, glycerin, dipropylene glycol , Tetraethylene glycol, triethylene glycol, N-methyl-2-
It is preferred to use one selected from pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and 2-pyrrolidone.

Further, according to a preferred embodiment of the present invention, the ink composition according to the present invention preferably contains a sugar, a tertiary amine, an alkali hydroxide, or ammonia.
Due to these additions, the pigment does not agglomerate or increase in viscosity even during long-term storage, and has excellent storage stability. It also has fluidity and re-dispersion even when left open (at room temperature while in contact with air). The ink composition can maintain high performance for a long time, and can have high ejection stability without clogging of nozzles at the time of restart during printing or after interruption of printing.

The saccharides that can be added to the ink composition according to the present invention include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, Ribose,
Xylose, arabinose, galactose, aldonic acid, glucitol, (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a sugar in a broad sense, and is used to include a substance widely existing in nature such as alginic acid, α-cyclodextrin, and cellulose. Further, derivatives of these saccharides are represented by reducing sugars of the above-mentioned saccharides (for example, sugar alcohols (general formula HOCH ₂ (CHOH) nCH ₂ OH, where n represents an integer of 2 to 5). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thiosugars, etc. Particularly preferred are sugar alcohols.
Specific examples include maltitol and sorbitol.

The content of these saccharides is 0.1 to 0.1% of the ink.
It is in the range of 40% by weight, more preferably 1 to 30% by weight.

The tertiary amine which can be added to the ink composition according to the present invention includes trimethylamine, triethylamine, triethanolamine, dimethylethanolamine, diethylethanolamine, triisopropenolamine, butyldiethanolamine and the like. These may be used alone or in combination.
The addition amount of these tertiary amines to the ink composition of the present invention is 0.1 to 10% by weight, more preferably 0.5 to 5% by weight.
% By weight.

The alkali hydroxides that can be added to the ink composition according to the present invention are potassium hydroxide, sodium hydroxide and lithium hydroxide. It is 5% by weight, preferably 0.05-3% by weight.

[0032] The ink composition of the present invention may further contain a surfactant. Examples of surfactants include:
Anionic surfactants (for example, sodium dodecylbenzenesulfonate, sodium laurate, ammonium salts of polyoxyethylene alkyl ether sulfate, etc.), nonionic surfactants (for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester) , Polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, etc.) and acetylene glycols (olefin Y, and Surfynol 82, 104,
440, 465, and 485 (all Air Products
and Chemicals Inc.). These can be used alone or in combination of two or more.

The ink composition according to the present invention may optionally contain a pH adjuster, a preservative, a fungicide, a phosphorus antioxidant, and the like.

[0034]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Preparation of Resin Emulsion 1 80 parts of styrene monomer, 0.1 part of 2-hydroxypropyl acrylate, 120 parts of water, 0.4 part of ammonium persulfate, and 0.6 part of potassium laurate are placed in a 1-liter flask and placed under a nitrogen gas atmosphere. Stir at ° C. Thereafter, the temperature was raised to 70 ° C., and stirring polymerization was continued for 3 hours, followed by cooling to 30 ° C. to complete the polymerization. Thus, a resin emulsion having a particle size of 90 nm is obtained. Production of Resin Emulsions 2 and 3 In the same manner as in Resin Emulsion 1, the amounts of styrene monomer and 2-hydroxypropyl acrylate were changed and the final stirring time was changed as shown in Table 1 below. A resin emulsion having the average particle size described therein was prepared. An ink composition having the following composition was prepared. Example 1 C. I. Pigment Yellow 74 3.5 wt% Styrene-acrylic copolymer / ammonium salt 1.5 wt% (molecular weight 7000, resin component 38 wt%: dispersant) Resin emulsion 1 3 wt% Glycerin 10 wt% 2-pyrrolidone 10 wt% Surfynol 465 1 wt% Triethylene glycol monobutyl ether 5 wt% Proxel XL2 0.3 wt% (preservative: manufactured by ZENECA) Ion-exchanged water balance

Example 2 An ink composition having the same composition as in Example 1 was obtained except that the resin emulsion 1 was changed to the resin emulsion 2.

Comparative Example 1 An ink composition having the same composition as in Example 1 was obtained as Comparative Example 1, except that the resin emulsion 1 was changed to the resin emulsion 3.

Storage stability evaluation test Each ink was allowed to stand in a high-temperature bath at 50 ° C. for one month, and changes in average particle diameter and viscosity before and after the standing were examined. Evaluation 1: The ink composition before and after leaving the average particle size was diluted 1000 times with pure water, and the average particle size of the solid component in the diluent was measured using Microtrac U.
It measured using PA-150. The change in the average particle size before and after standing was evaluated according to the following criteria. Evaluation A: Difference in average particle size is less than 30 nm. Evaluation B: The difference in average particle size is 30 nm or more and less than 50 nm. Evaluation C: The difference in average particle size is 50 nm or more and less than 100 nm.

Evaluation 2: Viscosity The particle size of the ink before and after standing was measured using a vibrating viscometer. The results were evaluated according to the following criteria. Evaluation A: Difference in viscosity is less than 0.2 mPa · s. Evaluation B: Difference in viscosity is 0.2 mPa · s or more and 0.5 mPa · s
Is less than. Evaluation C: Difference in viscosity is 0.5 mPa · s or more and 0.8 mPa · s
Is less than.

The results were as shown in the following table. Table 1 Styrene 2-hydroxypro Particle size (nm) Average particle size Viscosity monomer Pyrracrylate (parts by weight) (parts by weight) Example 1 80 0.190 A A Example 2 80 3.5 92 A A Comparative Example 1 80 6 88 C B

Continued on the front page F-term (reference) 2C056 FC01 2H086 BA53 BA55 BA59 BA60 BA62 4J039 AD01 AD02 AD04 AD09 AD10 AD11 AD12 AD23 BA04 BA13 BC17 BC39 BE01 BE12 BE22 CA06 EA36 EA41 EA44 EA47 GA24

Claims (16)

[Claims] 1. An ink composition comprising a pigment, water, a water-soluble organic solvent, and resin emulsion particles, wherein the resin emulsion particles have a structure derived from a hydrophobic monomer, and a hydrophilic monomer. And a structure 10 derived from a hydrophobic monomer.
With respect to 0 parts by weight, the structure derived from the hydrophilic monomer was added.
An ink composition comprising 0.01 to 5 parts by weight. 2. A resin emulsion particle comprising 0.1 to 3 parts by weight of a structure derived from a hydrophilic monomer based on 100 parts by weight of a structure derived from the hydrophobic monomer. 2. The ink composition according to item 1. 3. The resin emulsion particles having a particle size of 1 to 1
3. The ink composition according to claim 1, which has a thickness of 50 nm. 4. The resin emulsion particles having a particle size of 10 to 10.
The ink composition according to claim 3, which is 100 nm. 5. The ink composition according to claim 1, wherein the amount of the resin emulsion particles added is 0.1 to 10% by weight.
5. The ink composition according to any one of claims 1 to 4. 6. An ink composition according to claim 1, wherein the amount of said resin emulsion particles is 0.5 to 5% by weight.
5. The ink composition according to any one of 4. 7. The method according to claim 1, wherein the hydrophobic monomer has a polymerizable double bond and has a lipophilic hydrocarbon group, aromatic ring group, or alicyclic group. Item 10. The ink composition according to item 8. 8. A hydrophilic monomer having a polymerizable double bond and having a carboxyl group, a hydroxyl group, a hydroxymethyl group, an amino group, a sulfonic acid group, a polyethylene oxide group, a sulfate ester group, or phosphoric acid The ink composition according to any one of claims 1 to 7, which has an ester base. 9. The ink composition according to claim 1, wherein the resin emulsion has a single particle structure. 10. The ink composition according to claim 1, wherein the resin emulsion has a core-shell structure comprising a core portion and a shell layer surrounding the core portion. 11. The pigment according to claim 11, wherein the pigment is C.I. I. Pigment Yellow 74, 109, 110, 128, 138, 150, or 180. The ink composition according to any one of claims 1 to 10, wherein the composition is Pigment Yellow 74, 109, 110, 128, 138, 150, or 180. 12. The ink composition according to claim 1, further comprising a styrene-acryl resin as a dispersant. 13. An ink jet recording method,
The ink composition according to claim 1. 14. A recording method for printing on a recording medium by adhering an ink composition, wherein the ink composition according to claim 1 is used as the ink composition. 15. An ink jet recording method for ejecting droplets of an ink composition and attaching the droplets to a recording medium to perform printing, wherein the ink composition is any one of claims 1 to 13. An ink jet recording method using the ink composition described in the above. 16. A recording medium printed by the method according to claim 14. Description: