JP2003306624A - Ink composition for ink jet recording, method of recording and recorded material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition for ink jet printing imparting a printed matter having a sharp edge with high OD value, an excellent fixing property and water resistance and excellent in reliability. <P>SOLUTION: The ink composition for ink jet recording comprises a self- dispersing type pigment surfaces modified to a cation type, particles of an anionic resin having a zeta-potential of ≤-15 mV at pH 6 and an aqueous medium. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet which has a sharp edge and a high optical density (OD value) and has a good fixability and water resistance, especially for plain paper, recycled paper or coated paper. The present invention relates to a recording ink composition.

[0002]

2. Description of the Related Art An ink jet recording method is a printing method in which a droplet of ink is ejected and adhered to a recording medium such as paper for printing. As the ink, generally used are various water-soluble dyes dissolved in water or water and a water-soluble organic solvent. It is generally pointed out that an image formed from an ink containing such a water-soluble dye has poor water resistance and light resistance.

On the other hand, the ink obtained by dispersing the pigment in the aqueous medium has excellent water resistance and light resistance. For example, JP-A-64-6074 and JP-A-64-318
No. 81 discloses an aqueous pigment ink in which carbon black is dispersed with a surfactant or a polymer dispersant.
However, in these inks, when the ink content of the colorant is increased in order to increase the print density of the recorded matter, the ink viscosity may increase sharply with it. Further, an excessive amount of a surfactant or a polymer dispersant is required to stably disperse carbon black in the ink, which may cause deterioration of printing stability due to foaming or deterioration of defoaming property. there were.

In order to solve these problems, Japanese Unexamined Patent Publication No. Hei 8
No. 3498 and Japanese Unexamined Patent Publication No. 10-120958, a certain amount or more of surface-active hydrogen or a salt thereof is introduced on the surface of carbon black so that carbon can be obtained without a dispersant such as a surfactant or a polymer dispersant. Disclosed is a self-dispersion type carbon black dispersion liquid in which black alone can be dispersed in an aqueous solvent. In addition, JP-A-10-110
Japanese Patent Publication 127 discloses a method of introducing a sulfonic acid group on the surface of carbon black. Further, JP-A-10-
Japanese Patent No. 95941 proposes an inkjet ink containing the above-mentioned surface-modified carbon black and glycol ethers. Does not require dispersant as above
The so-called self-dispersion pigment, when used in an ink as a colorant, has an O. D. The value (optical density) is high, and it is easy to handle because the viscosity in the ink is easily adjusted to an appropriate range, and it is not necessary to consider the compatibility between the dispersant and various added solvents. Variously developed. On its surface, a hydrophilic functional group such as a carbonyl group, a carboxyl group, a hydroxyl group, a sulfone group, and an ammonium group is directly or indirectly bonded through an alkyl group, an aryl group, or the like to provide an anion-type surface modification. The ones that are common are.

In addition, Japanese Patent Application Laid-Open No. 10-183046, International Publication WO96 / 18696, and WO0
0/53681 also discloses a self-dispersion pigment surface-modified to a cationic type.

On the other hand, there is a problem that an image formed by an ink containing a pigment as a coloring agent is generally inferior in fixing property. That is, the image obtained with the ink using the pigment as the colorant is
The colorant component is likely to remain near the surface of the recording medium. Therefore,
If the colorant is not sufficiently fixed on the surface of the recording medium, the image will become dirty when the image is rubbed with a finger, or the image will become dirty when the image is marked with a marker pen etc. Is not enough print,
In particular, the anion-type surface-modified self-dispersion pigment does not contain a resin as a dispersant, and thus has poor abrasion resistance, and its self-dispersion has some problems in water resistance. It was In order to improve the fixing property of the colorant on the recording medium,
Proposals have been made to add resins to ink compositions. This resin is considered to firmly fix the colorant as a binder on the recording medium.

As an ink composition containing a resin, for example, an ink in which a pigment and a resin emulsion are dispersed in water is disclosed in JP-B-62-1426.
No. 68 discloses that a pigment is dispersed in a water-insoluble emulsion dispersion, and JP-A 1-217088 discloses that an emulsion having a specific film-forming temperature is used, and JP-A-4-18462 discloses. Similarly discloses an ink using a resin emulsion. Further, JP-A-56-147859 and JP-A-56-147860.
Japanese Patent Publication No. 4703/1992 and Japanese Patent Publication No. 4703/1997 propose an aqueous dispersion pigment ink using a polymer dispersant and a water-soluble organic solvent.

Further, in Japanese Patent No. 3141792,
It has been suggested that the combined use of the sulfonated surface-treated pigment and the water-dispersible resin improves the fixability of the pigment to the recording medium. International Publication WO98 / 21284 proposes an inkjet recording ink containing a pigment dispersible and / or soluble in water without a dispersant, a glycol ether, and a water-soluble emulsion having a film-forming temperature of room temperature or lower. It is described that the abrasion resistance of the recorded matter can be obtained. Japanese Patent Application Laid-Open No. 10-287837 discloses a pigment that can be dispersed and / or dissolved in water without a dispersant, and a core-shell type structure containing acrylic acid and / or methacrylic acid as a main component, and acrylic acid in the shell portion. An inkjet recording ink has been proposed which comprises a water-soluble emulsion composed of a resin having a carboxyl group of methacrylic acid on its surface, an acetylene glycol-based surfactant, a water-soluble organic solvent and water. JP 10-2
No. 92141 discloses an ink jet recording ink containing an inorganic material as a main component, a water-soluble pigment dispersible by a surface oxidation treatment, an aqueous resin emulsion or an aqueous dispersion, and an organic additive solid at 25 ° C. and water. Is proposed. JP-A-11-80639
Japanese Patent Laid-Open Publication No. 2003-242242 proposes an ink jet recording ink containing a water-soluble pigment, a specific penetrating agent, and a water-soluble emulsion composed of a resin having a shell portion cross-linked with a core-shell structure. Japanese Patent Application Laid-Open No. 2000-351931 discloses a self-dispersion type pigment which does not substantially contain a surfactant and a surfactant which has a charge of the same polarity as that of a self-dispersion type pigment and has a glass transition temperature of 35 ° C. or higher. Minimum film formation temperature is 20
Ink jet recording inks containing a self-dispersible resin emulsion at a temperature of not higher than 0 ° C have been proposed.

However, the ink compositions containing these emulsions are insufficient for obtaining a recorded material having a sharp edge and a high OD value and good fixing property and water resistance.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to have a sharp edge, a high OD value, and good fixability and water resistance. And to provide an ink composition for inkjet recording having excellent reliability.

[0011]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a self-dispersion pigment surface-modified into a cation type,
It was found that an ink composition for inkjet recording containing an anionic resin particle having a zeta potential of −15 mV or less at pH 6 and an aqueous medium can solve the above problems. The present invention is based on such findings. That is, the structure of the present invention is as follows.

(1) An ink jet comprising at least a cationic surface-modified self-dispersion pigment, anionic resin particles having a zeta potential of -15 mV or less at pH 6 and an aqueous medium. Recording ink composition.

(2) An ink composition for ink jet recording, wherein the resin particles are contained in an amount of 0.1 to 10% by weight based on the total amount of the ink composition for ink jet recording.

(3) An ink composition for ink jet recording, wherein the resin particles are resin particle emulsions obtained by emulsion polymerization of unsaturated monomers.

(4) An ink composition for ink jet recording, wherein the resin particles are resin fine particles which can be dispersed in water in the form of an aqueous emulsion.

(5) An ink composition for ink jet recording, wherein the self-dispersion pigment is contained in an amount of 1 to 15% by weight based on the total amount of the ink composition for ink jet recording.

(6) An ink composition for ink jet recording having a pH of 5 to 7.

(7) A recording method and a recorded matter for printing by adhering the ink composition for ink jet recording described above to a recording medium.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The ink composition for ink jet recording of the present invention will be described in detail below based on its preferred embodiments.

The ink composition for ink-jet recording of the present invention contains at least a cationic surface-modified self-dispersion pigment, anionic resin particles having a zeta potential of -15 mV or less at pH 6, and an aqueous medium. It is characterized in that Hereinafter, each component will be described in detail.

<Cation type self-dispersion pigment surface-modified> As a cation self-dispersion pigment, 4
Examples thereof include those having a cationic group such as a primary ammonium group and an amine group. Preferred cationic groups present ^{_{invention, (- NH 4 +),}} - (C 5 H 4 N +) CH 3, - (C 5
H ₄ N ⁺ ) C ₂ H ₅ , -C ₆ H ₄ (N ⁺ C ₆ H ₅ ), -C ₆ H ₄ C
OCH ₂ N ⁺ (CH ₃ ) ₃ , —C ₆ H ₄ COCH (N ⁺ C
₆ H ₅ ) and the like.

These cation-type self-dispersion pigments, when compared with anion-type self-dispersion pigments, in the combination with anionic resin particles, pigment aggregation due to an ionic reaction that occurs when the ink composition adheres to the recording medium. Therefore, it is presumed that a sharp edge can be formed and the OD value becomes high. Further, as described above, the self-dispersion pigment is inferior in fixing property by itself, but by combining with the anionic resin particles, abrasion resistance and water resistance can be realized.

The cationic self-dispersion pigment preferably has an average particle size of 1 to 300 nm, and more preferably 10 to 200 nm, from the viewpoints of ink storage stability and prevention of nozzle clogging. More preferably.

The cationic self-dispersion pigment is preferably in the range of 1 to 15% by weight, more preferably 5-1.
It is contained in the ink of the present invention in the range of 0% by weight. If the content is less than 1% by weight, the print density may be insufficient, and if the content is more than 15% by weight, the ink viscosity may increase, and problems such as nozzle clogging may occur.

<Anionic Resin> The ink composition for ink jet recording of the present invention contains anionic resin particles having a zeta potential at pH 6 of −15 mV or less.
The zeta potential is Zetasizer 3000 (Malver
It can be measured by a zeta potential measuring device such as a product manufactured by N. Co., Ltd. The resin particles contained in the ink composition for inkjet recording of the present invention have a zeta potential of −15 m at pH 6.
Since it is V or less, the resin particles themselves form a stable emulsion in the coexistence with the cationic self-dispersion pigment in the ink composition, and the pigment does not aggregate. Therefore, high stability can be secured as the ink composition for inkjet recording. On the other hand, when this ink composition adheres to a recording medium such as plain paper, recycled paper or coated paper, the binder ability of the resin particles causes
It can bind to a recording medium component such as cellulose and have a strong fixing property.

As these resins, acrylic resins,
Methacrylic resin, styrene resin, urethane resin,
One or more selected from the group consisting of an acrylamide resin and an epoxy resin is preferable, but from a resin particle emulsion (so-called “acrylic emulsion”) obtained by emulsion polymerization of unsaturated monomers It is preferable that

In the embodiment of the present invention, the resin particles are preferably resin fine particles which can be dispersed in water in the form of an aqueous emulsion. Here, "resin fine particles that can be dispersed in water in the form of an aqueous emulsion" refers to a form in which a substantially water-insoluble resin is dispersed in water in the form of fine particles, and is generally an emulsion, dispersion, latex or suspension. Including what is called.

In the present invention, resin particles having a single particle structure can be used. On the other hand, in the present invention, it is also possible to utilize fine resin particles having a core-shell structure composed of a core portion and a shell portion surrounding the core portion. In the present invention, the "core / shell structure" means "a form in which two or more kinds of polymers having different compositions are present in the particles in a phase-separated state". Therefore, not only the shell portion completely covers the core portion, but also the shell portion may partially cover the core portion. Further, a part of the shell part polymer may form a domain or the like in the core particle. Further, it may have a multilayer structure of three or more layers including one or more layers having different compositions between the core portion and the shell portion.

The resin fine particles used in the present invention are
It can be obtained by known emulsion polymerization. That is,
It can be obtained by emulsion polymerization of an unsaturated monomer in water in the presence of a polymerization catalyst and an emulsifier.

As the unsaturated monomer, acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers generally used in emulsion polymerization are used. , Vinyl cyan compound monomers, halogenated monomers, olefin monomers, diene monomers and the like.

Further, as specific examples, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate. , Dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate,
Acrylic acid esters such as; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n
-Butyl methacrylate, isobutyl methacrylate,
Methacrylic acid esters such as n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate; Vinyl esters such as vinyl acetate; vinyl cyanides such as acrylonitrile and methacrylonitrile; halogenated monomers such as vinylidene chloride and vinyl chloride;
Styrene, 2-methylstyrene, vinyltoluene, t-
Butyl styrene, chlorostyrene, vinyl anisole,
Aromatic vinyl monomers such as vinylnaphthalene; olefins such as ethylene, propylene and isopropylene;
Dienes such as butadiene and chloroprene; vinyl monomers such as vinyl ether, vinyl ketone and vinylpyrrolidone; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; acrylamide and N, N'- Acrylamides such as dimethylacrylamide; 2-hydroxyethyl acrylate, 2-
Examples thereof include hydroxyl group-containing monomers such as hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate, and these can be used alone or in combination of two or more.

Further, in the present invention, those having a structure crosslinked by a crosslinkable monomer having two or more polymerizable double bonds can be used. Examples of the crosslinkable monomer having two or more polymerizable double bonds include polyethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropoxyphenyl) propane, 2,2 ′ -A diacrylate compound such as bis (4-acryloxydiethoxyphenyl) propane, a triacrylate compound such as trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate, etc. , Ditrimethylolpropane tetraacrylate, tetramethylolmethane tetraacrylate, tetraacrylate compounds such as pentaerythritol tetraacrylate, hexaacrylate compounds such as dipentaerythritol hexaacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate,
Triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate,
Dimethacrylate compounds such as dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolethanetri Examples thereof include trimethacrylate compounds such as methacrylate, methylenebisacrylamide, and divinylbenzene, and these can be used alone or in combination of two or more.

Further, the resin fine particles having a core / shell structure are
It is produced by a known method, generally by multistage emulsion polymerization or the like. For example, it can be manufactured by the method disclosed in Japanese Patent Laid-Open No. 4-76004. The examples of the unsaturated monomer used for the polymerization are the same as those mentioned above.

The introduction of the epoxy group into the above-mentioned core is carried out by copolymerizing glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc. with another unsaturated monomer as the unsaturated monomer having an epoxy group. Examples thereof include a method and a method in which an epoxy compound is added at the same time when a core particle is prepared by polymerizing one or more unsaturated monomers to form a composite. The former method is preferable from the viewpoint of ease of polymerization, polymerization stability, and the like.

The polymerization initiator, emulsifier, and molecular weight modifier used in emulsion polymerization are used according to a conventional method.

As the polymerization initiator, those similar to those used in ordinary radical polymerization are used, and examples thereof include potassium persulfate, ammonium persulfate, hydrogen peroxide, azobisisobutyronitrile, benzoyl peroxide, and peroxide. Examples thereof include dibutyl oxide, peracetic acid, cumene hydroperoxide, t-butyl hydroxyperoxide and paramenthane hydroxyperoxide. Particularly, as mentioned above, when the polymerization reaction is carried out in water, a water-soluble polymerization initiator is preferable.

Examples of the emulsifier include, in addition to sodium lauryl sulfate, those generally used as anionic surfactants, nonionic surfactants or amphoteric surfactants, and mixtures thereof. These may be used alone or in a mixture of 2 It is possible to mix and use one or more species.

When the resin fine particles are produced by emulsion polymerization, particularly when a polymer emulsion composed of anionic resin fine particles is produced by emulsion polymerization, the surface of the resin fine particles has a negative group such as a carboxyl group or a sulfonic acid group. Because of the presence of the polar group, pH is inclined to the acidic side, and viscosity increase and aggregation are likely to occur. Therefore, neutralization with a basic substance is usually performed. As the basic substance, ammonia, organic amines, inorganic hydroxide and the like can be used. Among them, monovalent inorganic hydroxides (potassium hydroxide, sodium hydroxide, lithium hydroxide) are particularly preferable from the viewpoints of long-term storage stability and ejection stability of the polymer emulsion and the ink composition for inkjet recording.
The amount of the neutralizing agent added is appropriately determined so that the pH of the polymer emulsion is in the range of 6 to 8.5, preferably 6.5 to 7.5.

In the present invention, the resin fine particles may be mixed with other components in the ink composition as fine particle powder. However, after the resin fine particles are dispersed in water to form an emulsion, the resin fine particles are More preferably, it is mixed with the above ingredient.

From the viewpoint of long-term storage stability and ejection stability of the ink composition, the particle size of the resin fine particles preferred in the present invention is 5
To 400 nm, more preferably 50 to 20
It is in the range of 0 nm.

In the present invention, the above resin is 0.1 to 30% by weight based on the total amount of the ink composition for ink jet recording.
Is preferably contained in the range of 0.3 to 15% by weight
It is more preferable to be included in the range. If it is less than 0.1% by weight, the desired fixability may be insufficient, and if it is more than 30% by weight, problems such as rapid viscosity increase and unstable discharge may occur.

<Aqueous medium> The ink composition for ink jet recording of the present invention comprises an aqueous medium. By aqueous medium is meant a mixture of water and water-soluble organic compounds or water.

Water contained in the ink composition of the present invention is a main solvent, and it is preferable to use pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water or ultrapure water. In particular, it is preferable to use water that has been sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide, in order to prevent the generation of mold and bacteria and to enable long-term storage of the ink composition.
Water is preferably contained in the ink composition of the present invention in the range of 10 to 90% by weight, more preferably 30 to 80% by weight.

In the present invention, as the above water-soluble organic compound, a high boiling point organic solvent having water absorption and / or water retention can be used. As a result, it is possible to impart water retention and wettability to the ink composition and improve the resistance to clogging. As the water-absorbing / water-retaining high-boiling-point organic solvent that can be used in the present invention, those generally used in ink compositions for inkjet recording can be used as they are, and more specifically, glycerin,
Trimethylene glycol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2- Examples thereof include methyl-2,4-pentanediol, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and 2-pyrrolidone.

In the present invention, a solid wetting agent can be used as the water-soluble organic compound. In the present invention, the solid wetting agent means a water-soluble compound which has a water retaining function and is solid at 25 ° C. As the solid wetting agent that can be used in the present invention, those generally used in ink compositions for ink jet recording can be used as they are, and more specifically, sugars, sugar alcohols, hyaluronic acids, and trimethylol. Propane, 1,2,6-hexanetriol and ureas. Examples of sugars include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose,
Mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbit), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like can be mentioned. Here, the term "polysaccharide" means a sugar in a broad sense, and is meant to include substances widely existing in nature such as alginic acid, α-cyclodextrin, and cellulose. Examples of derivatives of these sugars include reducing sugars (for example, sugar alcohols) and oxidizing sugars (for example, aldonic acid, uronic acid, amino acids, and thiosugars) of the above-mentioned sugars. Sugar alcohol is particularly preferable, and specific examples thereof include maltitol, sorbitol, xylitol and the like. As the hyaluronate, a commercially available 1% aqueous solution of sodium hyaluronate (molecular weight: 350,000) can be used.

In the present invention, a penetrant can be used as the water-soluble organic compound. In the present invention, the penetrant means an additive that improves the permeability.
By using the penetrant, the aqueous solvent quickly penetrates into the recording medium, and a recorded matter with less image bleeding can be obtained. The penetrant used in the present invention includes 1,2-
Alkyl diols, glycol ethers and commonly used surfactants are preferable, and these can be used alone or in combination of two or more. In some cases, more preferable penetrability can be obtained by mixing and using two or more kinds. More specific penetrants used in the present invention are shown below. The 1,2-alkyldiols are selected from 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, 4-methyl-1,2-pentanediol and the like. Glycol ethers include dialkylene glycol monobutyl ether, dialkylene glycol monopentyl ether, dialkylene glycol monohexyl ether,
It is selected from trialkylene glycol monobutyl ether, trialkylene glycol monopentyl ether, trialkylene glycol monohexyl ether, tetraalkylene glycol monobutyl ether, tetraalkylene glycol monopentyl ether, tetraalkylene glycol monohexyl ether and the like. More specifically, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monobutyl ether, triethylene glycol monohexyl ether, triethylene glycol monopentyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether. It is selected from pentyl ether, tetraethylene glycol monohexyl ether and the like. Commonly used surfactants include anionic surfactants, cationic surfactants,
The amphoteric surfactant and the nonionic surfactant can be selected, but the nonionic surfactant is particularly preferable from the viewpoint of obtaining an ink composition with less foaming / foaming. Further specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene nonyl phenyl ethers, polyoxyethylene octyl phenyl ethers, polyoxyethylene dodecyl phenyl ethers, polyoxyethylene alkyls. Allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether,
Ether system such as polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearate ester,
Sorbitan laurate, sorbitan monostearate,
Ester-based agents such as sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate and polyoxyethylene stearate, silicon-based surfactants such as dimethylpolysiloxane, and other fluoroalkyl esters, perfluoroalkyl carboxylates, etc. Fluorine-containing surfactants and the like can be mentioned. Among the above nonionic surfactants, acetylene glycol-based surfactants and acetylene alcohol-based surfactants are particularly preferable in that they cause less foaming and have excellent defoaming performance. Further specific examples of the acetylene glycol surfactant and the acetylene alcohol surfactant include 2,4
7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyne-3-ol and the like can be mentioned. , Commercially available, for example, Surfinol 104, 82, 465 of Air Products Co.,
485, TG, Olfine STG manufactured by Nissin Chemical Co., Olphin E1010, and the like.

The amount of the water-soluble organic compound added is appropriately determined in consideration of the physical properties such as the viscosity of the ink composition, the desired wetting effect, and penetrating effect.

<Other Additives> In the ink composition for ink jet recording of the present invention, if necessary, a pH adjusting agent,
Antioxidants, UV absorbers, antiseptic / antifungal agents, etc. can be added.

As the pH adjustor, those conventionally used in ink compositions for ink jet recording for the purpose of setting pH within a specific range can be used. Specifically, lithium hydroxide, potassium hydroxide, alkali metal hydroxides such as sodium hydroxide, ammonia, alkaline substances such as amines such as triethanolamine, triisopropanolamine, diethanolamine, or the like, or
An acidic substance such as formic acid, acetic acid, dilute hydrochloric acid or dilute sulfuric acid can be used. As the pH buffer, those conventionally used in ink compositions for inkjet recording can be used for the purpose of maintaining pH within a specific range. Specifically, collidine, imidazole, phosphoric acid, 3- (N-morpholino) propanesulfonic acid, tris (hydroxymethyl) aminomethane, boric acid and the like can be used, and the ink composition for inkjet recording of the invention has a pH of 5 or less. ~ 7
It is preferable to adjust

As antioxidants / ultraviolet absorbers, alohanates such as alohanate and methyl alohanate,
Tinuvin 32 manufactured by Ciba-Geigy, such as biurets such as biuret, dimethyl biuret, and tetramethyl biuret, L-ascorbic acid and salts thereof, and the like.
8, 900, 1130, 384, 292, 123, 14
4, 622, 770, 292, Irgacor252,
153, Irganox 1010, 1076, 103
5, MD1024 or the like, or a lanthanide oxide or the like is used.

Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, and 2
-Pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, 1,2-
Dibenzisothiazolin-3-one (Proxel CRL, Proxel BDN, Proxel GX from Avecia)
L, Proxel XL-2, Proxel TN) and the like.

The ink composition for ink jet recording of the present invention is prepared by a conventionally known apparatus such as a ball mill, a sand mill,
An attritor, basket mill, roll mill or the like can be used to prepare the ink in the same manner as conventional inks. At the time of adjustment, it is preferable to remove coarse particles from the viewpoint of preventing clogging of the nozzle. The coarse particles are removed by, for example, filtering the ink obtained by mixing the above components with a filter such as a membrane filter or a mesh filter, and preferably 10 μm or more, more preferably 5 μm.
This is done by removing the above particles.

The ink composition for ink-jet recording of the present invention can be preferably used for writing instruments such as pens, stamps, etc., but can be more preferably used as an ink-jet recording ink. In the present invention, inkjet recording means a method in which an ink composition is discharged as droplets from a fine nozzle and the droplets are attached to a recording medium. A specific inkjet recording method will be described below.

As a first method, there is an electrostatic suction method, which applies a strong electric field between a nozzle and an accelerating electrode placed in front of the nozzle to continuously eject ink from the nozzle in a droplet form. It is a method of ejecting and printing a print information signal by applying it to the deflection electrodes while the ink droplets fly between the deflection electrodes, or a method of ejecting the ink droplets in accordance with the print information signal without deflecting.

A second method is a method of forcibly ejecting ink droplets by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal oscillator or the like. The ejected ink droplets are charged at the same time as the ejection, and while the ink droplets fly between the deflection electrodes, a print information signal is given to the deflection electrodes for recording.

The third method is a method using a piezoelectric element, in which pressure and a print information signal are simultaneously applied to the ink liquid by the piezoelectric element, and ink droplets are ejected / recorded.

The fourth method is a method in which the volume of the ink liquid is rapidly expanded by the action of heat energy, and the ink liquid is heated and foamed by the fine electrodes according to the print information signal, and the ink droplets are ejected and recorded.

Any of the above methods can be used in the ink jet recording method using the ink of the present invention.

The recorded matter of the present invention is recorded by using at least the above ink composition for ink jet recording. By using the ink of the present invention, this recorded matter has good print quality, D. It shows excellent quality with high value and good fixability and water resistance.

[0060]

EXAMPLES Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Cationic Self-Dispersion Pigment> The dispersions shown below are prepared from WO96 / 18696 and WO00 / 536.
It was manufactured according to the description of Japanese Patent No. 81 and used as Examples and Comparative Examples of the present invention.

Dispersion liquid (a) On the surface of carbon black
^{_{- (C 5 H 4 N +}} ) C 2 H 5 what was introduced dispersion (b) -C ₆ the carbon black surface H ₄ N ⁺ -
Introduced (CH ₃ ) ₃ Dispersion (C) C.I. I. Pigment Red 12
-(C ₅ H ₄ N ⁺ ) C ₂ H ₅ introduced on the surface of dispersion liquid (d) C.I. I. Pigment Yellow
-(C ₅ H ₄ N ⁺ ) C ₂ H ₅ introduced on the surface of dispersion liquid (e) C. I. Pigment Blue 1
-(C ₅ H ₄ N ⁺ ) C ₂ H ₅ introduced on the surface of 5: 3

<Resin Particle Emulsion> The following resin particle emulsions were prepared by the following method and used as Examples and Comparative Examples of the present invention.

(Emulsion 1) 900 g of ion-exchanged water and 4 g of sodium lauryl sulfate were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer.
Was charged, and the temperature was raised to 70 ° C. while substituting with nitrogen while stirring. Keeping the internal temperature at 70 ° C, add 2 g of potassium persulfate as a polymerization initiator, dissolve, and then ion-exchange water 450 in advance.
g, acrylamide 20 to 3 g of sodium lauryl sulfate
styrene 350g, butyl acrylate 600g,
An emulsion prepared by adding 30 g of methacrylic acid with stirring was continuously added dropwise to the reaction solution over 3 hours. After completion of dropping, aging was carried out at the same temperature for 3 hours. After cooling the obtained emulsion of resin particles to room temperature, ion-exchanged water and ammonia water are added to obtain a solid content of 35% by weight and pH.
A resin particle emulsion 1 of 6.5 was obtained. When the zeta potential of this emulsion was measured, at pH 6,
It was −52 mV.

(Emulsion 2) 400 g of ion-exchanged water and 2 g of sodium lauryl sulfate were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer.
Was charged, and the temperature was raised to 70 ° C. while substituting with nitrogen while stirring. Keep the internal temperature at 70 ° C, add 1 g of potassium persulfate as a polymerization initiator, dissolve, and then ion-exchange water 300 in advance.
g, 120 g of methyl methacrylate, 320 g of butyl acrylate, and 30 g of methacrylic acid were added to 3 g of sodium lauryl sulfate with stirring, and an emulsion produced was continuously added dropwise to the reaction solution over 3 hours. After completion of dropping, aging was carried out at the same temperature for 3 hours. After the obtained emulsion of resin particles was cooled to room temperature, ion-exchanged water and ammonia water were added to obtain a resin particle emulsion 2 having a solid content of 35% by weight and a pH of 7.5. When the zeta potential of this emulsion was measured, it was −34 mV at pH 6.

(Emulsion 3) 900 g of ion-exchanged water and 4 g of sodium lauryl sulfate were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer.
Was charged, and the temperature was raised to 70 ° C. while substituting with nitrogen while stirring. Keeping the internal temperature at 70 ° C, add 2 g of potassium persulfate as a polymerization initiator, dissolve, and then ion-exchange water 450 in advance.
g, 3 g of sodium lauryl sulfate, 435 g of styrene,
An emulsion prepared by adding 475 g of butyl acrylate, 30 g of methacrylic acid and 2 g of ethylene glycol dimethacrylate under stirring was continuously added dropwise to the reaction solution over 3 hours. After completion of dropping, aging was carried out at the same temperature for 3 hours. After the obtained emulsion of resin particles was cooled to room temperature, ion-exchanged water and sodium hydroxide were added to obtain a resin particle emulsion 3 having a solid content of 35% by weight and a pH of 8.0. When the zeta potential of this emulsion was measured, it was -15.5 mV at pH 6.

(Emulsion 4) 900 g of ion-exchanged water and 4 g of sodium lauryl sulfate were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer.
Was charged, and the temperature was raised to 70 ° C. while substituting with nitrogen while stirring. Keeping the internal temperature at 70 ° C, add 2 g of potassium persulfate as a polymerization initiator, dissolve, and then ion-exchange water 450 in advance.
g, acrylamide 20 to 3 g of sodium lauryl sulfate
g of styrene 435 g, butyl acrylate 475 g,
An emulsion prepared by adding 30 g of methacrylic acid with stirring was continuously added dropwise to the reaction solution over 3 hours. After completion of dropping, aging was carried out at the same temperature for 3 hours. After cooling the obtained emulsion of resin particles to room temperature, ion-exchanged water and ammonia water are added to obtain a solid content of 35% by weight and pH.
A resin particle emulsion 4 of 8.0 was obtained. When the zeta potential of this emulsion was measured, at pH 6,
It was −5 mV.

The zeta potential was measured by Zetasizer 3000 (Malvern Co., Ltd.).

The pigment, the resin particle emulsion, the organic solvent, and the ion-exchanged water (remaining amount, Table 1) were used in the amounts shown in Table 1 (% by weight of each component relative to the total weight of the ink composition).
(Not shown in FIG. 1) is mixed and stirred, filtered through a metal filter having a pore size of 5 μm, and deaerated using a vacuum pump,
To 6 and Comparative Examples 1 to 4 were obtained.

[0070]

The details of the organic solvent in Table 1 are as follows. TEGmBE; triethylene glycol monobutyl ether GL; glycerin TEG; triethylene glycol 1,2-HD; 1,2-hexanediol 2P; 2-pyrrolidone KOH; potassium hydroxide olphine E1010; acetylene glycol surfactant (Nisshin) Chemical Industry Co., Ltd. Olfine STG; Acetylene glycol surfactant (manufactured by Nissin Chemical Industry Co., Ltd.) EDTA; Sodium ethylenediaminetetraacetate dihydrogen diacetate (chelating agent) Proxel XL2; Antifungal agent (Avicia Co., Ltd.) )

Characters and solid prints were printed at a resolution of 720 dpi with an ink jet printer EM-930C (manufactured by Seiko Epson Corporation) using each of the prepared ink compositions. As a recording medium, Copyplus
(Manufactured by Hammermill), Xerox 4024
(Made by Xerox), Xerox P, XeroxR
(Fuji Xerox Co., Ltd.) and special plain paper (Seiko Epson Co., Ltd.)
Using the obtained sample (recorded matter), tests 1 to 4 shown below were evaluated. In addition, these evaluations took the average of the evaluations in various papers. Moreover, the following tests 5 to 6 were also evaluated as follows.

<Test 1; Print Quality (Observation of Edge)> After printing, the printed matter was magnified 50 times using a metallurgical microscope and the edge thereof was observed. The result was judged based on the following criteria. A: The edges are clear and there is no bleeding. B: There is a slight blur. C: Bleeding can be seen even without magnifying 50 times.

<Test 2; Optical density (OD value)> After printing,
The sample (recorded matter) was left for 1 hour in a general environment. After standing, the optical density of the solid portion was measured using a Gretag densitometer (manufactured by Gretag Co.) and judged based on the following criteria. A: Optical density is 1.3 or more. B: Optical density is 1.1 or more and less than 1.3. C: Optical density is less than 1.1.

<Test 3; abrasion resistance (line marker resistance)
> After printing, the sample (recorded matter) is naturally dried for 24 hours, and then a yellow water-based highlighter ZEBRA manufactured by Zebra
Use PEN2 (registered trademark) to print characters with a pen pressure of 300
It was rubbed with g / 15 mm, and the presence or absence of dirt was visually observed. The result was judged based on the following criteria. A: No smear occurs even if the same part is rubbed twice. B: Staining does not occur until rubbing once, but stains occur after rubbing twice. C: Contamination is generated by rubbing once.

<Test 4; Water Resistance> The state of the printed image (text and solid printing) after the water droplet was dropped on the printed portion of the sample (recorded material) and dried was visually confirmed. The state was judged based on the following criteria. A: No trace of water drops remains. B: A trace of water drops remains. C: Signs of water droplets remain considerably.

<Test 5; Storage Stability> 50 g of the ink composition was placed in an aluminum pack and left in an environment of 70 ° C. for 1 week. After standing, presence / absence of foreign matter (sediment) was determined, and in the case of no foreign matter, further changes in physical properties (viscosity, surface tension, pH, particle diameter) were determined based on the following criteria. A: No foreign matter is generated and the physical properties are not changed. B: No foreign matter is generated, but the physical properties are slightly changed. C: Foreign matter is generated.

<Test 6; Clogging property> Using an ink jet printer EM-930C, each head was filled with each ink, and after confirming that the ink composition was ejected from all the nozzles, there was no ink cartridge. And at a position outside the home position (the head is displaced from the position of the cap provided in the printer, and the head is not capped), and left for 1 week in an environment of 40 ° C.
After standing, the number of cleanings required until the ink composition was ejected from all the nozzles again was examined, and the number of cleanings was determined based on the following criteria. A: One cleaning. B: 2 to 5 times of cleaning. C: 5 times or more cleaning.

Table 2 shows the above evaluation results.

[0080]

As is apparent from Table 2, the ink compositions for ink jet recording of Examples 1 to 6 according to the present invention,
It has sharp edges, a high OD value, excellent scratch resistance and water resistance, and also has good reliability such as storage stability and clogging recovery.

On the other hand, when the anion type self-dispersion pigment is used, the sharpness of the edge is taken, and the ink composition containing no resin particles is inferior in print quality and fixability. When a resin particle emulsion having a zeta potential at pH 6 of more than −15 mV is used, or when the ink composition has a pH of more than 7, the storage stability and clogging are poor, and the reliability as an ink composition is poor. It became a call.

That is, according to the present invention, it is possible to provide an ink composition for inkjet recording which has a sharp edge and a high OD value, has good fixing property and water resistance, and is excellent in reliability.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 EA13 FC01                 2H086 BA15 BA33 BA36 BA41                 4J039 AB01 AD03 AD10 AD12 AD17                       AE04 AE05 BA04 BB00 BC33                       BE01 BE12 BE29 BE30 CA06                       EA38 EA43 EA48 GA24

Claims (8)

[Claims] 1. A self-dispersion pigment surface-modified to at least a cation type and having a zeta potential at pH 6 of -1.
An ink composition for inkjet recording, comprising anionic resin particles having a voltage of 5 mV or less and an aqueous medium. 2. The ink composition for ink jet recording according to claim 1, wherein the resin particles are contained in an amount of 0.1 to 10% by weight based on the total amount of the ink composition for ink jet recording. 3. The ink composition for inkjet recording according to claim 1, wherein the resin particles are resin fine particles that can be dispersed in water in the form of an aqueous emulsion. 4. The ink composition for ink jet recording according to claim 1, wherein the resin particles are a resin particle emulsion obtained by emulsion polymerization of unsaturated monomers. 5. The ink composition for ink jet recording according to claim 1, wherein the self-dispersion pigment is contained in an amount of 1 to 15% by weight based on the total amount of the ink composition for ink jet recording. object. 6. The ink composition for ink jet recording according to claim 1, which has a pH of 5 to 7. 7. A recording method for printing by adhering the ink composition for inkjet recording according to claim 1 to a recording medium. 8. A recorded matter recorded by the recording method according to claim 7.