JP3304802B2 - 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 water-based ink for ink-jet recording which has improved water resistance and prevents scorching to a printer head. .

[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.

[0005] In addition, there has been proposed a method of improving water resistance by containing a latex (Japanese Patent Application Laid-Open No. 55-18412). However, when latex is mixed, scorching by a printer head is severe, and also in a nozzle. The problem of clogging arises.

Accordingly, it is an object of the present invention to provide a water-based ink for ink-jet recording which further improves water resistance and hardly causes sticking to a printer head.

[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. It has been found that the water resistance of the ink is improved without impairing the coloring property of the ink. In addition, it has been found that a vinyl polymer aqueous dispersion having a specific structure is effective in suppressing scorching to a printer head, and the present invention has been completed.

That is, the present invention provides a silicone macromer (a-1) and an acrylamide monomer (a-2) or a methacrylamide monomer (a) represented by the following formula (1):
-3) (excluding those having a salt-forming group), one or more selected from the group consisting of (a), a polymerizable unsaturated monomer (b) having a salt-forming group, and A water dispersion (A) of a vinyl polymer obtained by copolymerizing a monomer and a copolymerizable monomer (c) in the presence of a radical polymerization initiator, wherein a hydrophobic dye is contained in the dispersion particles. (B) A water-based ink for ink-jet recording characterized by being enclosed.

X (Y) _n Si (R) _3-m (Z) _m (1) (where X represents a polymerizable unsaturated group; Y represents a divalent linking group; R represents hydrogen) Represents an atom, a lower alkyl group, an aryl group or an alkoxy group, and a plurality of R may be the same or different Z: represents a monovalent siloxane polymer moiety having a number average molecular weight of at least about 500. n: 0 or 1 is shown, and m represents an integer of 1 to 3.)

[0010]

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

The aqueous 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 includes a silicone macromer (a) represented by the above formula (1). -1) and an acrylamide-based monomer (a-2) or a methacrylamide-based monomer (a-3) (excluding those having a salt-forming group)
One or more selected from the group consisting of (a), a polymerizable unsaturated monomer (b) having a salt-forming group, and a monomer (c) copolymerizable with these monomers as a radical It is obtained by copolymerization in the presence of a polymerization initiator.

As a method for obtaining a vinyl polymer aqueous dispersion (A) encapsulating a hydrophobic dye, the vinyl polymer obtained as described above is dissolved in an organic solvent together with the hydrophobic dye (B). A method is preferred in which a salt-forming group in the polymer is ionized by adding a neutralizing agent, if necessary, and then water is added, followed by distilling off the organic solvent and inverting the aqueous phase.

In the silicon macromer (a-1) represented by the above formula (1) used in the present invention, X represents a polymerizable unsaturated group, specifically, CH ₂ CH—, CH _{2 2} =
And a group such as C (CH ₃ ) —. Y is a divalent linking group, in particular -COO-, -COOC _b H _2b - (wherein b is 1
5), a phenylene group and the like, and -COOC ₃ H ₆
-Is preferred. R represents a hydrogen atom; a lower alkyl group such as a methyl group or an ethyl group; an aryl group such as a phenyl group; an alkoxy group such as a methoxy group, with a methyl group being preferred. Z
Denotes a monovalent siloxane polymer moiety having a number average molecular weight of at least about 500, but preferably has a number average molecular weight of 8
00-5000 monovalent dimethylsiloxane polymer.
n is 0 or 1, but is preferably 1. m is 1
It is an integer of 3, preferably 1.

As such a silicon macromer,
For example, compounds represented by the following formulas (1-1) to (1-4) are exemplified.

[0016]

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(In the formula, R ′ is a hydrogen atom or a methyl group, R has the above-mentioned meaning, and a plurality of Rs may be the same or different.

[0018]

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And a represents a number of 5 to 65. Among these, a compound represented by the formula (1-1) is preferable, and a silicon macromer FM-0711 (manufactured by Chisso Corporation) having a structure represented by the following formula (1-1-1) is particularly preferable. .

[0020]

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(In the formula, a ′ is a number such that the weight average molecular weight becomes 1000.) The acrylamide monomer (a-2) or the methacrylamide monomer (a-2) having no salt-forming group used in the present invention. 3) (hereinafter abbreviated as (meth) acrylamide-based monomer) includes acrylamide, N- (1,1-dimethyl-3-oxobutyl) acrylamide (diacetoneacrylamide), N, N-dimethylacrylamide,
N, N-diethylacrylamide, N, N-diisopropylacrylamide, N, N-dibutylacrylamide, N, N
-Diphenylacrylamide, Nt-butylacrylamide, Nt-hexylacrylamide, Nt-octylacrylamide, N- (1-methylundecyl)
Acrylamide, N-isobornylacrylamide, N
-Norbornylacrylamide, N-adamantylacrylamide, N-benzylacrylamide, N- (4-
Methylphenyl) methylacrylamide, N-diphenylacrylamide, phthalimidomethylacrylamide,
Acrylamide hydroxyacetic acid, 3-acrylamide-
3-methylbutanoic acid, 10-acrylamide-undecylic acid, N- (2,2,2-trichloro-1-hydroxy) ethylacrylamide, N- (1,1,3,5-tetramethyl) octylacrylamide, N- ( 1,5-dimethyl-1-ethyl)
Acrylamide monomers such as hexyl acrylamide, Ni-propyl acrylamide, N-methylol acrylamide, N-cyclohexyl acrylamide, N- (1,1,3-trimethyl) butyl acrylamide, and methacrylamide, N- (1,1-dimethyl -3-oxobutyl) methacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N, N-diisopropylmethacrylamide, N, N-dibutylmethacrylamide, N, N-diphenylmethacrylamide, N- t-butyl methacrylamide, Nt-hexyl methacrylamide, Nt-octyl methacrylamide, N- (1-
Methylundecyl) methacrylamide, N-isobornyl methacrylamide, N-norbornyl methacrylamide, N-adamantyl methacrylamide, N-benzyl methacrylamide, N- (4-methylphenyl) methyl methacrylamide, N-diphenyl Methacrylamide,
Phthalimide methyl methacrylamide, N- (2,2,2-trichloro-1-hydroxy) ethyl methacrylamide, N
-(1,1,3,5-tetramethyl) octyl methacrylamide, N- (1,5-dimethyl-1-ethyl) hexyl methacrylamide, Ni-propyl methacrylamide, N-
Examples include, but are not limited to, methacrylamide monomers such as methylol methacrylamide, N-cyclohexyl methacrylamide, and N- (1,1,3-trimethyl) butyl methacrylamide.

As the polymerizable unsaturated monomer (b) having a salt-forming group used in the present invention, cationic monomers include unsaturated tertiary amine-containing monomers and unsaturated ammonium salt-containing monomers. Specific examples thereof include monovinylpyridines such as vinylpyridine, 2-methyl-5-vinylpyridine and 2-ethyl-5-vinylpyridine; N, N-dimethylaminostyrene, N, N-dimethylaminomethyl Styrenes having a dialkylamino group such as styrene; N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N
Acrylic acid such as diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminopropyl acrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate, N, N-diethylaminopropyl methacrylate Or esters having a dialkylamino group of methacrylic acid; vinyl ethers having a dialkylamino group such as 2-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'-dimethylamido) Propyl)
Acrylamide or methacrylamides having a dialkylamino group such as methacrylamide, N- (N ', N'-diethylaminopropyl) acrylamide, N- (N', N'-diethylaminopropyl) methacrylamide, or alkyl halides thereof. (Alkyl having 1 to 18 carbon atoms, chlorine, bromine, iodine as halogen), benzyl halide such as benzyl chloride or benzyl bromide, alkyl or arylsulfonic acid such as methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid. Examples thereof include those quaternized with a known quaternizing agent such as an alkyl ester (alkyl group having 1 to 18 carbon atoms) and dialkyl sulfate (alkyl group having 1 to 4 carbon atoms). Examples of the anionic monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer. Specifically, examples of the unsaturated carboxylic acid monomer include acrylic acid and methacrylic acid. , Crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like, or anhydrides and salts thereof, as unsaturated sulfonic acid monomers,
Styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconate, salts thereof, and other 2-hydroxyethyl ( There are sulfuric acid monoesters of meth) acrylic acid and salts thereof, and unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl -2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dioctyl-2
-(Meth) acryloyloxyethyl phosphate and the like.

The monomer (c) copolymerizable with the above monomer used in the present invention includes methyl acrylate,
Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-acrylate
Acrylates such as amyl, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate; Methacrylic acid n
-Butyl, isobutyl methacrylate, n-methacrylate
Methacrylates such as amyl, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate, dodecyl methacrylate; styrene, vinyltoluene, 2-methylstyrene, chlorostyrene Styrene-based monomers such as 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, polyethylene glycol acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate,
Examples include hydroxyl group-containing acrylates or methacrylates such as polyethylene glycol methacrylate.

In the present invention, when producing the vinyl polymer, one or more (a) compounds selected from the group consisting of the silicon macromer represented by the above formula (1) and a (meth) acrylamide monomer 1 to 40% by weight based on all monomer components, 3 to 40% by weight based on all monomer components of polymerizable unsaturated monomer (b) having a salt-forming group, and other monomers Preferably, component (c) is copolymerized at a rate of 0 to 89% by weight based on all monomer components.

The vinyl polymer of the present invention is produced by polymerizing the above monomers by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. It is preferably produced by a 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 from 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 (B) can be used without particular limitation as long as it is a dye which can be encapsulated in at least a dispersion formed by the vinyl polymer obtained as described above. Examples thereof include disperse dyes, direct dyes, acid dyes, and basic dyes, and it is particularly preferable to use oily dyes and disperse dyes from the viewpoint of good encapsulation.

The oily dye is not particularly limited, but examples thereof include CI Solvent Black 3,
7, 27, 29, 34, CI Solvent Yellow 14, 16, 2
9, 30, 56, 82, 93, 162, CI Solvent Red 1, 3, 8, 18, 24, 27, 43, 49, 51, 72, 73, 109, 1
22, 218, CI Solvent Violet 3, CI Solvent Blue 2, 11, 25, 35, 70, CI Solvent Violet 3,
Green 3, 7 and CI Solvent Orange 2.

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 ink jet 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.

The organic solvent used here is preferably a hydrophilic organic solvent, 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 vinyl polymer aqueous dispersion containing the hydrophobic dye thus obtained has a particle size of 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 aqueous vinyl polymer dispersion in which the hydrophobic dye is encapsulated is 1 to 50% by weight in terms of solid content in the ink. 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 aqueous ink of the present invention in an amount of 1 to 10% by weight, and more 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 aqueous ink for ink-jet recording of the present invention contains, in addition to the above-mentioned specific vinyl polymer dispersion in which water is used as a medium and a hydrophobic dye is encapsulated, various conventionally known additives such as polyhydric alcohols. 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.

[0045]

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[0046] _{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 has extremely excellent water resistance, and can prevent scorching on the printer head.

[0049]

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 to 6 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 Tables 1 and 2 as a polymerizable unsaturated monomer were used. The monomers and the polymerization chain transfer agent described in the column of the initially charged monomer No. 2 were charged, and nitrogen gas substitution was sufficiently performed. On the other hand, in the dropping funnel, the monomers and the polymerization chain transfer agent described in the column of dropped monomers in Tables 1 and 2, 60 parts of methyl ethyl ketone, 2,2'-azobis (2,4-dimethylvaleronitrile) 0.2 The part was charged after sufficient nitrogen replacement. 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 further added at 65 ° C. for 2 hours.
After aging 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 the hydrophobic dyes shown in Tables 1 and 2 were added to completely dissolve, and while stirring, 98 parts of a 30% aqueous solution of a base shown in Tables 1 and 2 was added thereto, and the copolymer was dissolved in the copolymer. After partially neutralizing the salt-forming groups and adding 1500 parts of ion-exchanged water, methyl ethyl ketone and acetone are completely removed at 60 ° C. under reduced pressure, and the water is further concentrated by removing a part of the water to obtain a solid content concentration. Is 13
By weight, a water-based dispersion of a vinyl polymer containing a hydrophobic dye was obtained.

[0053]

[Table 1]

[0054]

[Table 2]

Examples 1 to 6 80 parts of the vinyl polymer dispersion obtained in Production Examples 1 to 6, 10 parts of diethylene glycol, 10 parts of ion-exchanged water, 0.1 part of an antifoaming agent (KM-71 manufactured by Shin-Etsu Silicone Co., Ltd.) And the resulting dispersion is 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 3 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) Bleed Using the above printer, print alphanumeric characters on recycled paper for PPC (manufactured by Nippon Kikai Seisaku Co., Ltd.), leave it for one hour or more, and then use a microscope and visual inspection to determine the sharpness and character of the characters. 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 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
0 (4) Burning resistance Using the above-mentioned printer, five solid prints were made on A4-size recycled paper for PPC (manufactured by Nippon Kaishi Paper Co., Ltd.), and then the heating section in the ink cartridge was observed with a microscope.
The degree of scorching of the ink was evaluated according to the following criteria. ：: Burnt adhesion is not recognized. Δ: Burnt adhesion is slightly recognized. ×: Burnt adhesion is severe.

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 3 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%

[0061]

[Table 3]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-95366 (JP, A) JP-A-5-239392 (JP, A) JP-A-55-139471 (JP, A) JP-A-54-1979 58504 (JP, A) JP-A-54-146109 (JP, A) JP-A-7-118583 (JP, A) JP-A-4-359912 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C09D 11/00-11/20

Claims (3)

(57) [Claims] 1. A silicon mask represented by the following formula (1-1):
One or two or more (a) selected from the chroma (a-1) and a polymerizable unsaturated monomer (b) having a salt-forming group
And an aqueous dispersion (A) of a vinyl polymer obtained by copolymerizing a monomer (c) copolymerizable with these monomers in the presence of a radical polymerization initiator. A water-based ink for ink-jet recording, characterized by containing a hydrophobic dye (B). Embedded image (Wherein R ′ is a hydrogen atom or a methyl group, R is a hydrogen atom,
A secondary alkyl group, an aryl group or an alkoxy group,
The +3 Rs may be the same or different. a is 5 to 65
Indicates the number of ) 2. A vinyl polymer having a weight average molecular weight of 3,0
Aqueous ink for ink jet recording of claim 1, wherein in the range of 00～50,000. 3. A water dispersion (A) of a vinyl polymer in which a hydrophobic dye is encapsulated is represented by the above formula (1-1).
One or two selected from silicon macromers (a-1)
At least one species (a), a polymerizable unsaturated monomer (b) having a salt-forming group, and a monomer (c) copolymerizable with these monomers
And a vinyl polymer obtained by copolymerizing the polymer in the presence of a radical polymerization initiator together with a hydrophobic dye (B) are dissolved in an organic solvent, and if necessary, a neutralizing agent is added to ionize a salt-forming group in the polymer. , and then after adding water, it is prepared by phase inversion into an aqueous and distilling off the organic solvent, according to claim 1 or 2 water-based ink for inkjet recording according.