JP3322790B2 - Water-based ink for inkjet recording - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink for ink-jet recording, and more particularly, to a method of increasing the amount of a hydrophobic dye contained in an aqueous dispersion of a vinyl polymer so as to obtain a deep, vivid and water-resistant ink. The present invention relates to a further improved aqueous ink for inkjet recording.

[0002]

2. Description of the Related Art An ink jet recording system is a recording system in which ink droplets are directly ejected from a very fine nozzle to a recording member and adhered to obtain characters and images. According to this method, not only the device used has the advantage of low noise and good operability, but also
It is widely used in recent years because it has an advantage that it can be easily colored and that plain paper can be used as a recording member. As a method of ejecting ink, a piezoelectric type using a piezoelectric element in a printer head and a thermal jet type using a heater of a heating resistance element are widely used as personal printers.

[0003] In the ink used in the ink jet printer, a water-soluble dye and a polyhydric alcohol are usually used in order to prevent the ink from being clogged in the nozzles. By using a water-soluble dye, the ink is less likely to clog the nozzles, but on the other hand, has the problem of poor water resistance. There was a problem that the printer head was easily scorched.

In order to improve the water resistance of the ink for ink jet recording, a pigment is used as the ink (Japanese Patent Application Laid-Open Nos. 4-28776, 4-189876, 4-3599071, 4-35972). Gazette), use of a non-aqueous liquid medium (JP-A-4-26147)
No. 8) and using a dye having excellent water resistance (US Pat. No. 4,963,189). However, when a pigment is used as an ink, there is a possibility that a problem of causing a decrease in the saturation of a printed matter or a problem of causing clogging in a nozzle may occur. The improvement is not enough.

Further, an ink composition (Japanese Patent Laid-Open No. 55-139471) in which a disperse dye is present in a state in which a disperse dye is encapsulated in water-insoluble vinyl polymer latex particles has been proposed. And the storage stability is not sufficient.

Accordingly, an object of the present invention is to increase the amount of a hydrophobic dye contained in an aqueous dispersion of a vinyl polymer, to increase the color density,
It is an object of the present invention to provide a water-based ink for inkjet recording which is vivid and further improved in water resistance.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by using a vinyl polymer aqueous dispersion in which hydrophobic dyes are encapsulated in particles as an ink base, the dyes can be dyed. In order to find that the water resistance of the ink is improved without impairing the color developing property, and to obtain a sufficient dye content without impairing the stability of the ink, an aqueous vinyl polymer dispersion having a specific structure is effective. Thus, the present invention has been completed.

That is, the present invention relates to a styrene macromer comprising a homopolymer or copolymer of styrene having a polymerizable functional group at one end, a polymerizable unsaturated monomer having a salt-forming group, and a copolymer thereof. It contains an aqueous dispersion of a vinyl polymer obtained by copolymerizing a polymerizable monomer and a radical polymerization initiator in the presence of a radical polymerization initiator, and a hydrophobic dye is encapsulated in the dispersion particles. The present invention provides a water-based ink for ink-jet recording.

[0009]

Embodiments of the present invention will be described below in detail.

The water-based ink for ink-jet recording of the present invention is characterized by containing a specific vinyl polymer aqueous dispersion in which a hydrophobic dye is encapsulated in particles. That is, the hydrophobic dye is encapsulated in the particles of the aqueous dispersion formed by at least the vinyl polymer having the specific structure as described above.

The vinyl polymer used in the present invention is a polymer capable of forming a micelle capable of enclosing at least a part of a hydrophobic dye therein, and a single polymer of styrene having a polymerizable functional group at one end. It is obtained by copolymerizing a styrene macromer comprising a coalesced or copolymer, a polymerizable unsaturated monomer having a salt-forming group, and a monomer copolymerizable therewith in the presence of a radical polymerization initiator. Things.

As a method for obtaining an aqueous dispersion of a vinyl polymer in which a hydrophobic dye is encapsulated, the vinyl polymer obtained as described above is dissolved in an organic solvent together with the hydrophobic dye, and if necessary, a neutralizing agent is used. Is added to ionize the salt-forming group in the polymer, and then water is added. Then, the organic solvent is distilled off to convert the phase to an aqueous phase.

The styrene macromer used in the present invention is a homopolymer or a copolymer of styrene having a polymerizable functional group at one terminal, and has a weight average molecular weight of 1,000 to 10,000.
A range of 00 is preferred. If the molecular weight is less than 1,000, the dye introduction rate is not sufficient, and if it exceeds 10,000, the scorch becomes severe. As these styrene macromers, those having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end are particularly preferable. In addition, the ratio of the styrene unit constituting the styrene macromer and the copolymerizable monomer unit is such that the styrene unit is at least 60% by weight, preferably at least 70% by weight in all the constituent monomers, thereby ensuring a sufficient dye introduction rate. Desirable from the point. Monomers copolymerizable with styrene constituting the styrene copolymer include, but are not limited to, acrylonitrile and the like. Specific examples of such a styrene macromer include those having a structure represented by the following formula (1).

[0014]

Embedded image

(Where m and n are m / n = 6/4 to 10/0)
Indicates the number at which the weight average molecular weight becomes 1,000 to 10,000. Examples of the polymerizable unsaturated monomer having a salt-forming group used in the present invention include cationic monomers such as an unsaturated tertiary amine-containing monomer and an unsaturated ammonium salt-containing monomer. Is vinylpyridine, 2-methyl-
Monovinylpyridines such as 5-vinylpyridine and 2-ethyl-5-vinylpyridine; styrenes having a dialkylamino group such as N, N-dimethylaminostyrene and N, N-dimethylaminomethylstyrene; N, N-dimethyl Aminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate,
Esters having a dialkylamino group of acrylic acid or methacrylic acid, such as N, N-dimethylaminopropyl acrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate, N, N-diethylaminopropyl methacrylate; 2 Vinyl ethers having a dialkylamino group such as -dimethylaminoethyl vinyl ether; N- (N ', N'-dimethylaminoethyl) acrylamide, N- (N', N'-dimethylaminoethyl) methacrylamide, N- (N ', N'-diethylaminoethyl) acrylamide, N- (N', N'-diethylaminoethyl) methacrylamide, N- (N ', N'-dimethylaminopropyl) acrylamide, N- (N', N'-dimethyl Aminopropyl) methacrylamide, N- (N ', N'
-Diethylaminopropyl) acrylamide, N- (N ',
Acrylamide or methacrylamides having a dialkylamino group such as N'-diethylaminopropyl) methacrylamide, or an alkyl halide (having 1 to 18 carbon atoms in the alkyl group, chlorine as a halogen)
Bromine, iodine), benzyl halides such as benzyl chloride or benzyl bromide, alkyl or aryl sulfonic acids such as methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid alkyl ester (alkyl group having 1 to 18 carbon atoms), and Examples thereof include those quaternized with a known quaternizing agent such as dialkyl sulfate (the alkyl group has 1 to 4 carbon atoms). Also, as the anionic monomer,
There are unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like. Specifically, unsaturated carboxylic acid monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Acid, citraconic acid, 2-methacryloyloxymethyl succinic acid, etc., or anhydrides and salts thereof. Examples of unsaturated sulfonic acid monomers include styrene sulfonic acid,
Acrylamide-2-methylpropanesulfonic acid, 3-
Sulfopropyl (meth) acrylate, bis-
There are (3-sulfopropyl) -itaconic acid ester and the like and salts thereof, and other sulfuric acid monoesters of 2-hydroxyethyl (meth) acrylic acid and their salts. Examples of the unsaturated phosphoric acid monomer include vinylphosphonic acid and vinyl Phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate And dioctyl-2- (meth) acryloyloxyethyl phosphate.

The monomers copolymerizable with the above-mentioned monomers used in the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate and n-acrylic acid.
Butyl, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate,
Acrylic esters such as 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid n-amyl, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-methacrylic acid
-Methacrylates such as octyl, decyl methacrylate, dodecyl methacrylate; styrene-based monomers such as styrene, vinyl toluene, 2-methylstyrene and chlorostyrene; 2-hydroxyethyl acrylate,
-Hydroxypropyl acrylate, polyethylene glycol acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, hydroxyl group-containing acrylates such as polyethylene glycol methacrylate, and methacrylate.

In the present invention, when the vinyl polymer is produced, the styrene macromer is used in an amount of 1 to 20% by weight, preferably 5 to 15% by weight, based on all monomer components, and a polymerizable polymer having a salt-forming group. 10 saturated monomers to all monomer components
To 40% by weight, preferably 20 to 35% by weight, and other monomer components are 40 to 89% by weight, preferably
It is desirable to copolymerize at a ratio of 50 to 75% by weight.

The vinyl polymer of the present invention is prepared by subjecting a styrene macromer and the above monomer to known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization in the presence of a radical polymerization initiator. Although it is produced by polymerization, it is particularly preferable to produce it by a solution polymerization method.
As the solvent used in the solution polymerization method, a polar organic solvent is preferable, and a water-miscible organic solvent can be used by mixing with water. Examples of the organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol, and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; Preference is given to ethanol, acetone, methyl ethyl ketone or a mixture of these with water. These organic solvents can be used alone or in combination of two or more.

Examples of the radical polymerization initiator used in the above polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile),
2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate,
Azo compounds such as 2'-azobis (2-methylbutyronitrile) and 1,1'-azobis (1-cyclohexanecarbonitrile) are preferred. Organic peroxides such as t-butyl peroctoate, dicumyl peroxide, di-t-butyl peroxide, dibenzoyl oxide and the like can also be used. These polymerization initiators are preferably used in an amount of 0.001 to 2.0 mol%, particularly 0.01 to 1.0 mol%, based on the monomer mixture.

At the time of the above polymerization, a polymerization chain transfer agent may be further added. Specific examples of the polymerization chain transfer agent used include, for example, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan,
mercaptans such as t-tetradecyl mercaptan;
Xanthogen disulfides such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide and diisopropyl xanthogen disulfide; thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide Hydrocarbons such as pentaphenylethane; and acrolein, methacrolein, allyl alcohol, 2-ethylhexylthioglycolate, turbinolene, α-terpinene, γ-terpinene, dipentene, α-methylstyrene dimer (2,4-diphenyl- 4-Methyl-1-pentene is preferably 50 parts by weight or more), 9,10-dihydroanthracene, 1,4
-Unsaturated cyclic hydrocarbon compounds such as dihydronaphthalene, indene and 1,4-cyclohexadiene; xanthene,
And unsaturated heterocyclic compounds such as 2,5-dihydrofuran. These may be used alone or in combination of two or more.

The polymerization is usually carried out at 30 to 100 ° C., preferably at 50 to 100 ° C.
The reaction is performed at 80 ° C. for 1 to 10 hours, and is appropriately selected depending on the type of the radical polymerization initiator, the monomer, and the solvent to be used.
The polymerization is preferably performed in an atmosphere of an inert gas such as nitrogen. After polymerization, reprecipitation from the reaction solution, solvent evaporation, etc.
The copolymer can be isolated by a known method. The obtained copolymer can be purified by repeating reprecipitation or removing unreacted monomers and the like by membrane separation, chromatographic method, extraction method and the like.

The weight average molecular weight of the thus obtained vinyl polymer of the present invention is preferably 3,000 to 50,000, in view of the scorching property of the printer head, the durability of the ink after printing, and the formability of the dispersion. Is preferred.

In the present invention, the hydrophobic dye can be used without particular limitation as long as it is a dye which can be encapsulated in a dispersion formed by at least the vinyl polymer obtained as described above. And direct dyes, acid dyes, and basic dyes, but it is particularly preferable to use oily dyes and disperse dyes from the viewpoint of good encapsulation.

The oil-based dye is not particularly limited, and examples thereof include CI Solvent Black 3,
7, 27, 29, 34, CI Solvent Yellow 14, 16, 2
9, 56, 82, CI Solvent Red 1, 3, 8, 18, 2
4, 27, 43, 51, 72, 73, CI Solvent Violet 3, CI Solvent Blue 2, 11, 70, CI Solvent Green 3, 7 and CI Solvent Orange 2
And the like.

The disperse dye is not particularly limited, but a preferred example is CI Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 93, 99, 10
0, 119, 122, 124, 126, 160, 184: 1, 186, 198, 199,
204, 224, 237, CI Disperse Orange 13, 29,
31: 1, 33, 49, 54, 55, 66, 73, 118, 119, 163, CI
Disperse Red 54, 60, 72, 73, 86, 88, 91, 9
2, 93, 111, 126, 127,134, 135, 143, 145, 152, 153,
154, 159, 164, 167: 1, 177, 181, 204, 206,207, 22
1, 239, 240, 258, 277, 278, 283, 311, 323, 343, 34
8, 356, 362, CI Disperse Violet 33, C.
I. Disperse Blue 56, 60, 73, 87, 113, 128, 14
3, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 18
5, 197, 198, 201, 214, 224, 225, 257, 266, 267, 28
7, 354, 358, 365, 368, CI Disperse Green
6: 1,9.

The hydrophobic dye used in the present invention is preferably dissolved in an organic solvent in an amount of 2 g / l or more, preferably 20 to 500 g / l, from the viewpoint of being efficiently encapsulated in the vinyl polymer by phase inversion emulsification described below. More preferably, it is dissolved.

The aqueous vinyl polymer dispersion in which the dye used in the aqueous ink for inkjet recording of the present invention is encapsulated is preferably produced by a phase inversion emulsification method. That is,
The vinyl polymer obtained by polymerization is dissolved in an organic solvent together with a hydrophobic dye, a neutralizing agent is added if necessary to ionize the salt-forming groups in the polymer, and then water is added. It can be obtained by leaving and inverting the phase to an aqueous system.

Hereinafter, the phase inversion emulsification method will be described in detail. First, the vinyl polymer and the hydrophobic dye are dissolved in an organic solvent. In this case, it is preferable to dissolve 5 to 50 parts by weight of the vinyl polymer and 0.1 to 50 parts by weight of the hydrophobic dye in 100 parts by weight of the organic solvent in order to obtain an aqueous dispersion having good stability.

As the organic solvent used here, a hydrophilic organic solvent is preferable, and specific examples thereof include alcohol-based, ketone-based, and ether-based solvents. Examples of alcohol solvents include methanol, ethanol,
Examples include n-propanol, isopropanol, n-butanol, secondary butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of ketone solvents include acetone, methyl ethyl ketone,
Examples thereof include diethyl ketone, dipropyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone. Examples of the ether solvent include diethyl ether, dibutyl ether, tetrahydrofuran, dioxane and the like. Of these, isopropanol, acetone and methyl ethyl ketone are preferred. These hydrophilic organic solvents may be used alone or in combination of two or more. If necessary, a high boiling point hydrophilic organic solvent may be used in combination. Examples of the high boiling point hydrophilic organic solvent include phenoxyethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, and 3-methyl-3- Butoxybutanol and the like.

Next, if necessary, a neutralizing agent is added to the organic solvent solution of the vinyl polymer and the hydrophobic dye to ionize the salt-forming groups in the vinyl polymer. As the neutralizing agent, a known acid or base may be used depending on the type of the salt-forming group. Examples of the acid include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid, propionic acid, lactic acid, succinic acid, and glycolic acid. Examples of the base include, but are not limited to, tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide, and the like. The degree of neutralization is not particularly limited, but it is preferable to neutralize the aqueous dispersion of the obtained self-dispersible polymer fine particles so that the liquidity of the aqueous dispersion is weakly acidic to neutral.

After the addition of the neutralizing agent, water (ion-exchanged water) is added to the organic solvent, and the system is heated under reduced pressure to remove the organic solvent and a predetermined amount of water. Then, the vinyl polymer dispersion of the present invention having a predetermined solid content concentration is obtained. The amount of water to be added is preferably 100 to 300 parts by weight based on 100 parts by weight of the organic solvent after the addition of the neutralizing agent. In this case, a general dispersant may be added to the organic solvent.

The particle size of the aqueous dispersion of vinyl polymer encapsulated with the hydrophobic dye thus obtained is 0.01 to 0.50 μm.
m is preferable. If the particle diameter is less than 0.01 μm, bleeding of the ink occurs, and if it exceeds 0.50 μm, the stability of the dispersion may be impaired. More preferably, the particle size is 0.02 to 0.15 μm.

In the aqueous ink for ink jet recording of the present invention, the polymer content in the vinyl polymer aqueous dispersion in which the hydrophobic dye is encapsulated is 1 to 50% by weight in terms of solid content. Is preferred, and 2 to 30
More preferably, it is blended by weight. If the amount of the vinyl polymer is less than 1% by weight, the print density is insufficient. If the amount is more than 50% by weight, the dispersion stability of the ink decreases, or the amount of the liquid increases due to ink evaporation at the nozzle tip. The head may be clogged due to the aggregation of the viscosity and the particles, and therefore, it is preferable to be within the above range.

On the other hand, the hydrophobic dye is preferably incorporated in the water-based ink of the present invention in an amount of 1 to 10% by weight, preferably 1.5 to 5% by weight.
More preferably, it is blended by weight. If the amount of the hydrophobic dye is less than 1% by weight, the printing density is insufficient,
If it exceeds 10% by weight, the stability with time of the aqueous dispersion is reduced and the particle size tends to increase.

The water-based ink for ink-jet recording of the present invention contains, in addition to the above-mentioned specific vinyl polymer dispersion containing water as a medium and a hydrophobic dye, various known additives such as a polyhydric alcohol. Wetting agents, such as
It is preferable to add a dispersant, an antifoaming agent, a fungicide, and / or a chelating agent.

Examples of the humectant include polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycol mono n-butyl ether, and ethers and acetates thereof. N−
One or more nitrogen-containing compounds such as methyl-2-pyrrolidone and 1,3-dimethylimidazolidinone can be used. The amount of these wetting agents is not particularly limited, but may be preferably 0.1 to 50% by weight, more preferably 0.1 to 30% by weight, in the ink.

The dispersant is not particularly limited, but anionic, nonionic and cationic dispersants can be used as long as the stability of the vinyl polymer dispersion is not impaired. The defoaming agent is not particularly limited, but it is particularly preferable to use a compound represented by the following formula (2) from the viewpoint of suppressing the generation of bubbles and adjusting the surface tension of the ink during the preparation of the ink.

[0038]

Embedded image

[0039] _{wherein, R 1, R 2, R} 3 and R ₄ are the same or different and each represents a phenyl group which may have an alkyl group or a substituent having 1 to 10 carbon atoms, R ₅ and R ₆ is the same or different and represents an alkyl group having 1 to 10 carbon atoms, a phenyl group which may have a substituent, a hydroxyl group, an amino group, a carboxyl group or an epoxy group, and p and q are the same or different , 0
And an integer of from 1000 to 100, preferably from 10 to 100. As the compound represented by the above formula (2), for example, KF96, 66, 69, KS68, 604, 6 manufactured by Shin-Etsu Silicone Co., Ltd.
07A, 602, 603, KM73, 73A, 73E, 72, 72A, 72
C, 72F, 82F, 70, 71, 75, 80, 83A, 85, 89, 90,
68-1F, 68-2F and the like.

The amount of the defoaming agent is not particularly limited, but is preferably 0.001 to 2.0 in the aqueous ink for inkjet recording of the present invention.
% By weight, preferably 0.005 to 0.5% by weight
More preferably, it is blended. Antifoam compounding amount is 0.0
If the amount is less than 01% by weight, bubbles are easily generated during ink adjustment,
In addition, it is difficult to remove small bubbles in the ink. If it exceeds 2.0% by weight, the generation of bubbles is suppressed, but at the time of printing, repelling occurs in the ink and the printing quality is reduced. Is preferred.

The water-based ink for ink-jet recording of the present invention thus obtained can contain a sufficient amount of a hydrophobic dye and has extremely excellent water resistance.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Production Examples of the vinyl polymer dispersion according to the present invention, and Examples and Comparative Examples of the aqueous ink of the present invention. However, the present invention is not limited to these. Needless to say, it is not done. In the examples, parts and percentages are by weight unless otherwise specified.

Production Examples 1-2 In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen introduction tube, 20 parts of methyl ethyl ketone as a polymerization solvent, and as a polymerizable unsaturated monomer, The monomers described in the column of charged monomers and the polymerization chain transfer agent were charged, and nitrogen gas replacement was sufficiently performed. On the other hand, in the dropping funnel, the monomer and polymerization chain transfer agent described in the column of dropped monomer in Table 1 and methyl ethyl ketone 60 were added.
Part, 2,2'-azobis (2,4-dimethylvaleronitrile)
0.2 parts were charged after sufficiently purging with nitrogen. Under a nitrogen atmosphere, the temperature of the mixed solution in the reaction vessel was raised to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. Two hours after the completion of the dropwise addition, a solution prepared by dissolving 0.1 part of 2,2′-azobis (2,4-dimethylvaleronitrile) in 5 parts of methyl ethyl ketone was added, and the mixture was further aged at 65 ° C. for 2 hours and at 70 ° C. for 2 hours. A copolymer solution was obtained.

A part of the obtained copolymer solution was removed under reduced pressure.
After drying at 105 ° C. for 2 hours, the solvent was completely removed and the mixture was isolated. The molecular weight was measured by gel permeation chromatography using polystyrene as a standard substance and tetrahydrofuran as a solvent, and the weight-average molecular weight was about 10,000. Was.

Acetone 10 was added to the copolymer solution obtained above.
Then, 33.4 parts of a hydrophobic dye shown in Table 1 and 33.4 parts of a hydrophobic dye shown in Table 1 were added to completely dissolve the mixture.
After partially neutralizing the salt-forming groups in the copolymer by adding 1,500 parts of ion-exchanged water, completely remove methyl ethyl ketone and acetone at 60 ° C. under reduced pressure, and further remove a part of water. As a result, a hydrophobic dye-encapsulated vinyl polymer aqueous dispersion having a solid content of 10% by weight was obtained.

[0046]

[Table 1]

Note) * 1 Styrene macromer A: manufactured by Toa Gosei Co., Ltd., trade name AN-6 (styrene / acrylonitrile copolymer macromer, styrene content 70% by weight, weight average molecular weight 6,000) * 2 Styrene macromer B: Toa AS-6 (Styrene homopolymerized macromer, weight average molecular weight: 6,000), manufactured by Gosei Co., Ltd. Examples 1-2: 80 parts of the aqueous dispersion of the vinyl polymer obtained in Production Examples 1-2, 10 parts of diethylene glycol, and glycerin 10 And 0.1 part of an antifoaming agent (KM-71 manufactured by Shin-Etsu Silicone Co., Ltd.), and the obtained dispersion was filtered through a 0.2 μm filter.
The water-based ink was obtained by removing dust and coarse particles. The physical properties of the obtained ink were evaluated by the following methods.
Table 2 shows the results.

<Evaluation method> (1) Print density Printing was performed using a commercially available Micro Bubble Jet Printer (model number BJ-10VL) manufactured by Canon Inc.
Solid printing was carried out on recycled paper for C (manufactured by Nippon Kaishi Paper Co., Ltd.), and after natural drying at room temperature for 24 hours, the optical density was measured with a Macbeth densitometer RD918 (manufactured by Mac11 Cubes).

(2) Bleeding Using the above-mentioned printer, alphanumeric characters are printed on recycled paper for PPC (manufactured by Nippon Kikai Seisaku Co., Ltd.), left for one hour or more, and then the sharpness of the characters and the characters are visually observed under a microscope and visually. The degree of mustache-like bleeding was evaluated according to the following criteria. ：: The character is sharp and has no bleeding. Δ: The character is not sharp and a little bleeding occurs. X: The character is not sharp and there is much bleeding.

(3) Water resistance Using the above-mentioned printer, solid printing was performed on recycled paper for PPC (manufactured by Nippon Kaishi Paper Co., Ltd.), dried for 1 hour or more, immersed vertically in still water for 10 seconds, and Raised to.
After naturally drying at room temperature, the print density of the same print was measured using the Macbeth densitometer, and the water resistance was determined from the following equation. Water resistance (%) = print density after immersion / initial print density x 10
Comparative Examples 1 and 2 As comparative examples, inks were prepared by using the water-soluble dyes used in ordinary ink jet recording inks according to the following formulation. The physical properties of the obtained ink were evaluated in the same manner as in the above examples. Table 2 shows the results.

<Ink of Comparative Example 1> CI Direct Yellow 132 1.5% Diethylene glycol 7.5% Glycerin 2.5% Deionized water 88.5% <Ink of Comparative Example 2> CI Acid Red 52 1.5% Triethylene glycol 10% 1,2,6 -Hexanetriol 5% Deionized water 83.5%

[0052]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-188600 (JP, A) JP-A-3-250069 (JP, A) JP-A 62-95366 (JP, A) JP-A 55- 139471 (JP, A) JP-A-54-58504 (JP, A) JP-A-9-40895 (JP, A) JP-A-5-239392 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (5)

(57) [Claims] 1. A styrene macromer comprising a homopolymer or copolymer of styrene having a polymerizable functional group at one end, a polymerizable unsaturated monomer having a salt-forming group, and a monomer copolymerizable therewith. Water dispersion containing a vinyl polymer obtained by copolymerizing a monomer with a monomer in the presence of a radical polymerization initiator, wherein a hydrophobic dye is encapsulated in the dispersion particles. System ink. 2. The styrene macromer has a weight average molecular weight of
2. The aqueous ink for inkjet recording according to claim 1, wherein the amount is 1,000 to 10,000. 3. A styrene macromer has a acryloyloxy group or a methacryloyloxy group at one terminal, styrene <br/> Le emissions copolymer copolymerization ratio is more than 60 wt% in total monomer styrene or styrene heavy 3. The method according to claim 1, which is a union.
The aqueous ink for inkjet recording according to the above. 4. A vinyl polymer having a weight average molecular weight of 3,0
The aqueous ink for inkjet recording according to any one of claims 1 to 3, wherein the water-based ink has a range of from 00 to 50,000. 5. An aqueous dispersion of a vinyl polymer in which a hydrophobic dye is encapsulated has a styrene macromer comprising a homopolymer or copolymer of styrene having a polymerizable functional group at one end, and a salt-forming group. A vinyl polymer obtained by copolymerizing a polymerizable unsaturated monomer and a monomer copolymerizable therewith in the presence of a radical polymerization initiator is dissolved in an organic solvent together with a hydrophobic dye, and 5. A method according to claim 1, wherein a salt-forming group in the polymer is ionized by adding a neutralizing agent, and then water is added. The aqueous ink for inkjet recording according to claim 1.