JP2001187852A - Inkjet recording ink - Google Patents

Abstract

(57) [Problem] To provide an ink jet recording ink which is excellent in ozone resistance and excellent in jetting characteristics such as scorching in a printer head and clogging in a nozzle. An ink jet recording ink containing an acid neutralized product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink for ink jet 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 onto a recording member and adhered to obtain characters and images. According to this method, not only has the advantage that the device to be used has low noise and good operability, but also has the advantage that colorization is easy and plain paper can be used as a recording member.
It has been widely used in recent years. In particular, the full-color recording technique has a feature that a vivid image with high saturation is obtained as compared with other recording methods because a dye having a rich color tone is used.

In the case of aqueous inks, most of the dyes used in the ink jet recording are water-soluble dyes such as acid dyes and direct dyes. For example, water-soluble dyes having light resistance and sufficient color tone and lightness are used. No dye has yet been obtained.

[0004] In particular, in the case of ink jet recording, the printed dye is merely adsorbed on the surface layer of the recording paper, and the dye is not protected by a binder or a protective film as in silver halide photography and thermal systems. For this purpose, the dye is usually exposed to oxygen, moisture, gas and the like in the air at all times.

[0005] Further, the dye is deteriorated by light to cause discoloration and fading. The deterioration of the dye due to the light can be suppressed to some extent by a suitable ultraviolet absorber or light stabilizer.

However, even when no light is irradiated, discoloration and fading of the dye occur. In this case, these additives are hardly effective.

It has been pointed out that the cause of discoloration and fading of the dye when no light is irradiated is an oxidizing gas, and this phenomenon is reproduced by an ozone exposure test. Regarding the improvement of ozone resistance, a method of adding a stabilizer to the ink (JP-A-64-75282) and a method of applying a stabilizer to the recording medium (JP-A-7-266689) are known. It has been disclosed. However, none of them is sufficient, and there is a problem that the type of dye or recording medium is limited in order to exhibit an excellent ozone resistance effect.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording ink which is excellent in ozone resistance and excellent in jetting characteristics such as scorching in a printer head and clogging in a nozzle. As an issue.

[0009]

That is, the gist of the present invention is as follows.
The present invention relates to an ink jet recording ink containing an acid neutralized product.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet recording ink of the present invention has one major feature in that an acid neutralized product is incorporated. By blending the acid neutralized product, it is possible to obtain an ink jet recording ink having excellent ozone resistance and excellent jetting characteristics in an ink jet system such as no scorching in a printer head or clogging in a nozzle. Can be.

The acid neutralized product is obtained by neutralizing an acid and a base.

Examples of acids include formic acid, acetic acid, trifluoroacetic acid, isobutyric acid, n-butyric acid, isovaleric acid, n-valeric acid, crotonic acid, pyruvic acid, propionic acid, β-hydroxypropionic acid, gluconic acid, Monovalent carboxylic acids such as glyoxylic acid, glycolic acid, sorbic acid, dehydroacetic acid, benzoic acid, salicylic acid, p-hydroxybenzoic acid, ascorbic acid, erythorbic acid, mucochloroic acid, and carbonic acid; oxalic acid, malic acid, lactic acid, and succinic acid Acid, malonic acid, fumaric acid, maleic acid, adipic acid, sebacic acid, tartaric acid, glutaric acid, α-ketoglutaric acid, phthalic acid, itaconic acid, diglycolic acid, mesaconic acid, tricarballylic acid,
Trans-aconitic acid, citric acid, D-glucuronic acid,
Polycarboxylic acids such as isocitric acid, meso-1,2,3,4-butanetetracarboxylic acid and pyrometic acid, sulfonic acids such as toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid and 2-naphthalenesulfonic acid, and phosphorus Acid group-containing compounds such as acids. Specific examples of the polymerized acid include homopolymers such as polystyrene-sulfonic acid, poly (meth) acrylic acid, polymaleic acid, polyitaconic acid, and polyphosphoric acid, and copolymers with other monomers. When a copolymer is used, other monomers include hydroxyl group-containing monomers such as styrene, alkyl (meth) acrylates (C _{1 to} C ₁₂ ) and 2-hydroxyethyl (meth) acrylate, silicone macromers, and methoxy polyethylene glycol. (1-30) (meth) acrylates and the like. The higher the glass transition temperature of the polymer, the better. Specifically, from the viewpoint of ozone resistance, 30 ° C. or higher is preferable. Among these acids, from the viewpoint of ozone resistance, polyvalent carboxylic acids and / or polyvalent acids which are polymerized acids are preferable, and polyvalent carboxylic acids are more preferable. Among polyvalent carboxylic acids, glutaric acid, citric acid, malonic acid, adipic acid and maleic acid are particularly preferable, and as a polymerized acid, polymaleic acid is particularly preferable.

Examples of the base include inorganic bases such as sodium hydroxide and potassium hydroxide; ammonia, allylamine, aminomethane, trimethylamine, aminoethane,
Aminobutane, 1-amino-3-methylbutane, 1-aminopropane, 2-aminoethanol, diethanolamine, triethanolamine, 1-amino-2-propanol, 3-amino-1-propanol, 3-amino-1,2- Propanediol, n-butylamine, tert-butylamine, Nn-butylethanolamine, diethylamine, 2-diethylaminoethylamine, isopropanolamine, diisopropanolamine, triisopropanolamine, N-methylethanolamine, N-methyldiethanolamine, 2- (2
-Aminoethoxy) Ethanol and amines such as 2- (2-dimethylaminoethoxy) ethanol and other tertiary amines, hexamethylenediamine, dodecamethylenediamine, diethylenetriamine and triethylenetetramine. Examples of the polymerized base include polymers such as an unsaturated tertiary amine-containing polymer and an unsaturated ammonium salt-containing polymer. Among these, N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide and the like are preferred. When used as a copolymer, other monomers include styrene, alkyl (meth) acrylate (C ₁ -C ₁₂ ),
Examples include a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate, a silicone macromer, and methoxypolyethylene glycol (1 to 30) (meth) acrylate. The higher the glass transition temperature of the polymer, the better. Specifically, from the viewpoint of ozone resistance, 30 ° C. or higher is preferable. Among these bases, amines such as ammonia, allylamine, 2-aminoethanol, hexamethylenediamine and triethanolamine are preferred from the viewpoint of ozone resistance, and primary amines such as 2-aminoethanol and hexamethylenediamine are preferred. Is particularly preferred.

The method for neutralizing the acid and the base may be any known method. Further, the combination of the acid and the base constituting the acid neutralized product may be any of a monovalent acid and a monovalent base, a polyvalent acid and a monovalent base, and a monovalent acid and a polyvalent base. However, a combination of a polyvalent acid and a monovalent base is particularly preferable for achieving both improvement in ozone resistance and improvement in storage stability.

Typical examples of the acid neutralized product are not particularly limited, but from the viewpoint of the effect on ozone resistance, ammonium glutarate, aminoethanol adipate, triethanolamine citrate, methyl methacrylate-methacrylic acid. A sodium hydroxide neutralized product of a copolymer, sodium polystyrene sulfonate, a maleic acid-styrene copolymer aminoethanol neutralized product, and the like are preferable. These acid neutralized products may be used alone or in combination of two or more.

The degree of neutralization of the acid-neutralized product may be any of 1 to 100%. However, since the degree of neutralization is related to the pH of the ink, the degree of neutralization must be taken into consideration in combination with a coloring agent and other additives. It is preferable to appropriately adjust the degree of neutralization to an optimum degree. For example,
When a dye containing an azo group is used, it is desirable to adjust the degree of neutralization so that the pH is 3 to 10, preferably 5 to 8, from the viewpoint of the stability of the dye. The degree of neutralization can be measured at 25 ° C. by using a glass electrode type hydrogen ion concentration meter (manufactured by Horiba, Ltd.).

The content of the acid neutralized product in the ink is preferably from 0.1 to 30% by weight from the viewpoint of printing stability.
0.1 to 10% by weight is more preferred. The content is preferably 0.1% by weight or more from the viewpoint of obtaining a sufficient anti-fading effect. In addition, excellent dispersion stability of the ink can be obtained, and the content of the liquid accompanying the evaporation of the ink at the nozzle tip can be improved. From the viewpoint that thickening and aggregation of particles do not occur and clogging of the head does not occur, the content is preferably 30% by weight or less.

The coloring agent used in the present invention includes:
Any of a water-soluble dye, a hydrophobic dye, and a pigment can be used. In consideration of water resistance, hydrophobic dyes and pigments are more preferable than water-soluble dyes.

Examples of the water-soluble dye include direct dyes, acid dyes, basic dyes, reactive dyes, food dyes and the like.

As direct dyes, CI Direct Black 2, 4, 9, 11, 14, 17, 19, 22, 27, 32, 36, 3
8, 41, 48, 49, 51, 56, 62, 71, 74, 75, 77, 78, 8
0, 105, 106, 107, 108, 112, 113, 117, 132,
146, 154, 194; CI Direct Yellow 1, 2,
4, 8, 11, 12, 24, 26, 27, 28, 33, 34, 39, 41, 4
2, 44, 48, 50, 51, 58, 72, 85, 86, 87, 88, 98, 100
, 110, 132; CI Direct Orange 6, 8, 1
0, 26, 29, 39, 41, 49, 51, 102; CI Direct
Red 1,2,4,8,9,11,13,17,20,23,24,
28, 31, 33, 37, 39, 44, 46, 47, 48, 51, 59, 62,
63, 73, 75, 77, 80, 81, 83, 84, 85, 90, 94, 99, 10
1, 108, 110, 145, 189, 197, 220, 224, 225
, 226, 227, 230; CI Direct Violet 1
, 7,9,12,35,48,51,90,94; CI Direct Blue 1,2,6,8,15,22,25,34,69,70,7
1, 72, 75, 76, 78, 80, 81, 82, 83, 86, 90, 98, 9
9, 106, 108, 110, 120, 123, 158, 163, 165
, 192, 193, 194, 195, 196, 199, 200, 201
, 202, 203, 207, 218, 236, 237, 239, 246
, 258; CI Direct Green 1, 6, 8, 28, 3
3, 37, 63, 64; CI Direct Brown 1A, 2, 6
, 25, 27, 44, 58, 95, 100, 101, 106, 112, 173
, 194, 195, 209, 210, 211 and the like.

Examples of the acid dye include CI Acid Black 1, 2, 7, 16, 17, 24, 26, 28, 31, 41, 48, 52,
58, 60, 63, 94, 107, 109, 112, 118, 119, 121
, 122, 131, 155, 156; CI Acid Yellow 1
, 3,4,7,11,12,13,14,17,18,19,23,2
5, 29, 34, 36, 38, 40, 41, 42, 44, 49, 53, 55, 5
9, 61, 71, 72, 76, 78, 99, 111, 114, 116, 122
, 135, 161, 172; CI Acid Orange 7, 8
, 10, 33, 56, 64; CI Acid Red 1, 4, 6
, 8, 13, 14, 15, 18, 19, 21, 26, 27, 30, 32, 3
4, 45, 37, 40, 42, 51, 52, 54, 57, 80, 82, 83, 8
5, 87, 88, 89, 92, 94, 97, 106, 108, 110, 111
, 119, 129, 131, 133, 134, 135, 154, 155
, 172, 176, 180, 184, 186, 187, 243, 249
, 254, 256, 260, 289, 317, 318; CI Acid Violet 7, 11, 15, 34, 35, 41, 43, 49, 7
5; CI Acid Blue 1, 7, 9, 22, 23, 25, 27,
29, 40, 41, 43, 45, 49, 51, 53, 55, 56, 59, 62, 7
8, 80, 81, 83, 90, 92, 93, 102, 104, 111, 113
, 117, 120, 124, 126, 145, 167, 171, 175,
183, 229, 234, 236; CI Acid Green 3,
12, 19, 27, 41, 9, 16, 20, 25; CI Acid Brown 4, 14, and the like.

The basic dyes include CI Basic Black 2, 8; CI Basic Yellow 1, 2, 11,
12, 14, 21, 32, 36; CI Basic Orange 2, 1
5, 21, 22; CI Basic Red 1, 2, 9, 12, 1
3, 37; CI Basic Violet 1, 3, 7, 1
0, 14; CI Basic Blue 1, 3, 5, 7, 9, 2
4, 25, 26, 28, 29; CI Basic Green 1, 4
CI Basic Brown 1, 12 and the like.

As the reactive dye, CI Reactive.
Black 1,3,5,6,8,12,14; CI Reactive Yellow 1,2,3,13,14,15,17; CI Reactive Orange 2,5,7,16,20,24 ; CI Reactive Red 6, 7, 11, 12, 15, 17, 21, 23, 24,
35, 36, 42, 63, 66, 180; CI Reactive Violet 2, 4, 5, 8, 9; CI Reactive Blue
2, 5, 7, 12, 13, 14, 15, 17, 18, 19, 20, 21, 2
5, 27, 28, 37, 38, 40, 41, 71; CI reactive
Green 5, 7; CI Reactive Brown 1, 7,
16 and the like.

As food coloring, CI Food Black
2; CI Food Yellow 3, 4, 5; CI Food Red 2, 3, 7, 9, 14, 52, 87, 92, 94, 102, 10
4, 105, 106; CI Food Violet 2; CI Food Blue 1, 2; CI Food Green 2, 3, and the like.

Examples of the hydrophobic dye include oil dyes, disperse dyes, direct dyes, acid dyes, basic dyes and the like.
Among these, oil-based dyes and disperse dyes are preferred from the viewpoint of using them as an aqueous dispersion of a polymer and a dispersant.

Examples of the oil-based dye include CI Solvent Black, CI Solvent Yellow, CI Solvent Red, CI Solvent Violet, CI Solvent Blue, CI Solvent Green, CI Solvent Orange and the like.

Examples of the disperse dye include CI Disperse Yellow, CI Disperse Orange, CI Disperse Red, CI Disperse Violet, CI Disperse Blue, and CI Disperse Green Series.

The pigment may be either an inorganic pigment or an organic pigment. If necessary, extenders can be used in combination with them.

Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, metal chloride and the like. Among these, carbon black is particularly preferred for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.

Examples of the organic pigment include an azo pigment, a diazo pigment, a phthalocyanine pigment, a quinacridone pigment, an isoindolinone pigment, a dioxazine pigment, a perylene pigment, a perinone pigment, a thioindigo pigment, an anthoraquinone pigment, and a quinophthalone pigment.

Examples of the extender include silica, calcium carbonate, talc and the like.

These coloring agents may be used alone or in combination of two or more. The content of the colorant in the ink is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight.

The coloring agent may be added as it is to form an ink, or may be added in the state of a coloring material to form an ink. In the present invention, the “coloring material” contains a coloring agent and water. Examples of the coloring agent include a dye and a pigment. As the coloring agent, any of a water-soluble dye, a hydrophobic dye and a pigment can be used. In the case of hydrophobic dyes and pigments,
It can be used as an aqueous dispersion of polymer particles containing hydrophobic dyes and pigments or various dispersants, or as an aqueous dispersion of hydrophobic dyes and pigments provided with self-dispersibility. The polymer may have a salt-forming group, and the salt-forming group may be neutralized to be an acid-neutralized product (hereinafter, referred to as a polymer-neutralized product). Removed from acid neutrals.

When a water-insoluble coloring agent is used, the method for producing the coloring material includes, for example, a macromer having a polymerizable functional group (hereinafter referred to as component (a)) and a polymerizable unsaturated monomer having a salt-forming group. A monomer (hereinafter referred to as component (b)) and a copolymerizable monomer (hereinafter referred to as component (c)) in the presence of a radical polymerization initiator [hereinafter referred to as component (d)]
A coloring agent is added to a vinyl polymer solution (copolymer solution) obtained by copolymerization by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, and a dispersion polymerization method. Then, if necessary, a method of emulsifying using a phase inversion emulsification method, a forced emulsification method, or the like can be given.

The component (a) is represented by the formula (I): X (Y) _n Si (R ¹ ) _3-m (Z) _m (I) (where X is a polymerizable unsaturated group; Y is 2 A valent linking group;
R ¹ may be the same or different and each represents a hydrogen atom, a lower alkyl group, an aryl group or an alkoxy group;
Z is a residue of a monovalent siloxane polymer having a number average molecular weight of 500 or more; m is an integer of 1 to 3; n is 0 or 1); and a polymerizable functional group at one end. It is preferably at least one selected from the group consisting of a styrene-based macromer and a (meth) acryl-based macromer having a polymerizable functional group at one end. Here, “(meth) acryl” means methacryl or acryl.

The styrenic macromer may be a homopolymer of styrene or a copolymer with another monomer, and the (meth) acrylic macromer may be a homopolymer of acrylic acid or methacrylic acid ester or a copolymer with another monomer. It may be a polymer. These macromonomers can be used alone or
More than one species may be used in combination.

In the silicone macromer represented by the formula (I), X represents a polymerizable unsaturated group. Specific examples include a CH ₂ CHCH— group and a CH ₂ CC (CH ₃ ) — group. Y represents a divalent linking group. Specifically, -COO- group, -COOC _b H
_{A 2b} -group (where b represents an integer of 1 to 5); a phenylene group; and the like, and a -COOC ₃ H ₆ -group is preferable. In R ¹ , a hydrogen atom; a carbon atom having 1 to 4 carbon atoms such as a methyl group and an ethyl group.
A lower alkyl group; an aryl group such as a phenyl group; an alkoxy group having 1 to 4 carbon atoms such as a methoxy group; and a methyl group is particularly preferable. Z is preferably a number average molecular weight of 8
It is a monovalent dimethyl siloxane polymer of 00 to 5000.
n is preferably 1. m is an integer of 1 to 3, and is preferably 1. Specific examples of the silicone macromer represented by the formula (I) include a silicone macromer
FM-0711 (trade name, manufactured by Chisso Corporation).

The styrenic macromer is a styrene homopolymer having a polymerizable functional group at one end or a copolymer of styrene and another monomer, and has a weight average molecular weight of
1000 to 10,000 is preferred. The weight average molecular weight is preferably 1,000 or more from the viewpoint of stabilizing the aqueous dispersion, efficiently forming an aqueous dispersion of vinyl polymer particles, and without causing scorching to the head or clogging of the nozzle during ejection,
From the viewpoint of obtaining a good image, it is preferably 10,000 or less. Among these, those having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end are preferable. The styrene content of the copolymer is preferably at least 60% by weight, more preferably at least 70% by weight, from the viewpoint of sufficiently securing the stability of the aqueous dispersion. Examples of the other monomer include, but are not limited to, acrylonitrile. Specific examples of such styrene macromers include styrene macromers AS-6 and AN-6 (both manufactured by Toagosei Co., Ltd., trade names)
And the like.

As the (meth) acrylic macromer,
A (meth) acrylate homopolymer having a polymerizable functional group at one end or a copolymer with another monomer may be mentioned, and its weight average molecular weight is preferably 1,000 to 10,000. The weight average molecular weight is preferably 1,000 or more from the viewpoint of stabilizing the aqueous dispersion of the vinyl polymer particles, and efficiently forms the aqueous dispersion of the vinyl polymer particles, causing burning to the head during ejection and clogging of the nozzle. It is preferably 10,000 or less from the viewpoint that no good image is obtained without occurrence of the image. As these (meth) acrylic macromers, those having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end are particularly preferable. The content of the (meth) acrylic acid ester in the copolymer is desirably 60% by weight or more, preferably 70% by weight or more, from the viewpoint of sufficiently securing the stability of the aqueous dispersion. Examples of the other monomer include, but are not limited to, styrene, vinyl acetate, and acrylonitrile. Specific examples of such a (meth) acrylic macromer include isobutyl methacrylate macromer AW-6S (Toagosei Co., Ltd., trade name, weight average molecular weight 6000) from the viewpoint of the stability of the aqueous dispersion. .

The component (b) includes a cationic monomer and an anionic monomer having a salt-forming group. Examples of the cationic monomer include an unsaturated tertiary amine-containing monomer, an unsaturated ammonium salt-containing monomer, and the like. Specifically, vinyl pyridine, 2-methyl-5
Monovinylpyridines such as -vinylpyridine and 2-ethyl-5-vinylpyridine; styrenes having a dialkylamino group such as N, N-dimethylaminostyrene and N, N-dimethylaminomethylstyrene; N, N-dimethylamino Ethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N
Esters having a dialkylamino group of (meth) acrylic acid, such as -dimethylaminopropyl acrylate, N, N-dimethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate, N, N-diethylaminopropyl methacrylate; 2-dimethylamino Vinyl ethers having a dialkylamino group such as ethyl 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'-dimethylaminopropyl) methacrylamide, N- (N ', N'-diethylaminopropyl) acrylamide, N- (Meth) acrylamides having a dialkylamino group such as (N ', N'-diethylaminopropyl) methacrylamide, or alkyl halides thereof (an alkyl group having 1 to 18 carbon atoms, chlorine, bromine, and iodine as halogen); Benzyl halides such as benzyl chloride or benzyl bromide, alkyl or aryl sulfonic acids such as alkyl esters of methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid (alkyl groups having 1 to 18 carbon atoms), and dialkyl sulfates (carbon A known quaternizing agent such as an alkyl group
And the like.

Examples of the anionic monomer include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers and the like. Specifically, the unsaturated carboxylic acid monomers include acrylic acid, Methacrylic acid,
Crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethylsuccinic acid, etc., or anhydrides and salts thereof; unsaturated sulfonic acid monomers include styrene sulfonic acid, 2-acrylamide-2- Methylpropanesulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconate, and salts thereof,
Sulfuric acid monoesters of hydroxyethyl (meth) acrylic acid and salts thereof; 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.

As the component (c), 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,
Hydroxyl-containing monomers such as hydroxyl-containing acrylates or methacrylates such as polyethylene glycol methacrylate; methoxy polyethylene glycol (1 to 3)
0: Number of moles of alkylene oxide added. The same applies hereinafter) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) (meth) acrylate, ethoxypolyethylene glycol (1 to 30) (meth) acrylate, (iso) propoxypolyethylene glycol (1 to 30)
30) (meth) acrylate, butoxy polyethylene glycol (1-30) (meth) acrylate, methoxy polypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol copolymerization) (1-30, among them) Ethylene glycol: 1 to 29) (meth) acrylate and the like,
These can be used alone or in combination of two or more. Among these, methoxypolyethylene glycol (1-30) (meth) acrylate is preferred. In addition, "(meth) acrylate" in this specification shows acrylate or methacrylate. “(Iso) propoxy” indicates n-propoxy or isopropoxy.

In the present invention, the content of the component (a) in the vinyl polymer is 1 to 40% by weight, and the content of the components (b) and (c) in the vinyl polymer is 60 to 40% by weight.
Preferably it is 99% by weight.

As the component (d), for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy −
2,4-dimethylvaleronitrile), dimethyl-2,2'-azobisbutyrate, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (1-cyclohexanecarbonitrile), etc. And peroxides such as t-butyl peroxide, dicumyl peroxide, di-t-butyl peroxide, dibenzoyl oxide, potassium persulfate and ammonium persulfate.

The component (d) is preferably used in an amount of 0.001 to 2.0 mol%, particularly 0.01 to 1.0 mol%, based on the total amount of the components (a) to (c).

During the polymerization, a polymerization chain transfer agent may be further added. Examples of the polymerization chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, and t-tetradecyl mercaptan; dimethyl xanthogen disulfide, diethyl xanthogen Xanthogen disulfides such as disulfide and diisopropylxanthogen disulfide; thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; pentaphenylethane and the like Hydrocarbons; and acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate, turbinole , Alpha-terpinene, .gamma.-terpinene, dipentene, alpha-methyl styrene dimer (2,4 - diphenyl-4-methyl-1-
Preferably, the pentene is at least 50 parts by weight) and 9,
Unsaturated cyclic hydrocarbon compounds such as 10-dihydroanthracene, 1,4-dihydronaphthalene, indene, and 1,4-cyclohexadiene; and unsaturated heterocyclic compounds such as xanthene and 2,5-dihydrofuran. These may be used alone or in combination of two or more. Usually, the amount of the polymerization chain transfer agent is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the charged monomer.

The polymerization conditions for the components (a) to (c) are as follows:
The polymerization temperature is usually from 30 to 100 ° C., preferably from 50 to 80 ° C., and the polymerization time is usually from about 1 to 10 hours, depending on the type of the component (c) and the solvent. The polymerization atmosphere is preferably an inert gas atmosphere such as a nitrogen gas.

After completion of the polymerization reaction, the copolymer can be isolated from the reaction solution (also referred to as a vinyl polymer solution or a copolymer solution) by a known method such as reprecipitation or solvent evaporation. The obtained copolymer can be purified by repeating reprecipitation or removing unreacted monomers and the like by membrane separation, chromatography, extraction and the like.

The weight average molecular weight of the vinyl polymer (measured by the method described in Examples described later) is determined to be 3,000 from the viewpoint of the scorching property of the printer head, the durability of the ink after printing, and the forming property of the dispersion. ~ 50000 is preferred, 3000 ~ 2000
0 is more preferred.

The obtained vinyl polymer solution is emulsified by an emulsion polymerization method or a dispersion polymerization method as it is, or by a phase inversion emulsification method or a forced emulsification method when a solution polymerization method or the like is used. Thus, an aqueous dispersion (colorant) of vinyl polymer particles containing a coloring agent can be obtained.

As the phase inversion emulsification method or the forced emulsification method, for example, the vinyl polymer obtained by polymerization is dissolved in an organic solvent, and if necessary, a neutralizing agent is added to ionize the salt-forming groups in the polymer. Then, after adding water and performing ultrasonic treatment or the like as necessary, an organic solvent is distilled off to convert the phase to an aqueous phase.

In this case, for 100 parts by weight of the organic solvent,
It is preferable to dissolve 5 to 50 parts by weight of the vinyl polymer (solid content weight) from the viewpoint of obtaining an aqueous dispersion having good stability.

The organic solvent used here is preferably a good solvent for vinyl polymer, and specifically, methanol, ethanol, n-propanol, isopropanol, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl isobutyl Examples include ketone, diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, benzene, toluene, dichloroethane, chloroform and the like. Of these, acetone, methyl ethyl ketone, toluene and dichloroethane are preferred from the viewpoint of solubility. These hydrophilic organic solvents are 1
Species or a mixture of two or more species is used, and if necessary,
A high boiling 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.

As the neutralizer, a known acid or base may be used depending on the type of the salt-forming group. As the acid,
Examples thereof 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, and potassium hydroxide. The degree of neutralization is not particularly limited, but it is desirable to neutralize the aqueous dispersion of the obtained self-dispersible polymer particles so that the liquidity of the aqueous dispersion is weakly acidic to weakly basic.

After the addition of the neutralizing agent, water such as 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, an aqueous dispersion (coloring material) of vinyl polymer particles containing a coloring agent 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 vinyl polymer particles in the coloring material thus obtained is preferably from 0.01 to 0.50 μm, more preferably from 0.02 to 0.15 μm. From the viewpoint that the effect of addition is efficiently obtained, the particle size is 0.01 μm.
m or more, and preferably 0.50 μm, from the viewpoint of ensuring the stability of the dispersion.

Further, the ink of the present invention may contain a wetting agent. It is preferable to use a wetting agent that is liquid at room temperature. Specifically, polyhydric alcohols, for example, polyhydric alcohols such as diethylene glycol, glycerin, and propylene glycol; alkyl ethers of the polyhydric alcohols and acetates thereof (for example, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, etc.) ); Hydroxyalkylformamides; N-vinyl-2-pyrrolidone oligomer and the like are preferably used. These wetting agents can be used alone or in combination of two or more. The content of the wetting agent in the ink is preferably 5 to 40% by weight, more preferably 5 to 20% by weight.

If necessary, a water-soluble solvent, a surface tension adjuster, a viscosity adjuster, a fungicide, a preservative, an anti-fading agent, etc. may be added to the ink of the present invention. .
These additives may be used alone or in combination of two or more.

Solvents soluble in water include, for example, dioxane, acetone, dimethylformamide, N-methyl-
2-pyrrolidone and the like.

As the surface tension modifier, for example, a cationic surfactant such as sodium alkyl sulfate;
Anionic surfactants such as alkylpyridium sulfate;
Nonionic surfactants such as polyoxyethylene alkyl ether; and amphoteric surfactants such as alkyl betaine.

Examples of the viscosity modifier include hydroxypropyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol and the like.

Examples of the fungicides and preservatives include isopropyl alcohol, sodium dehydroacetate, 6-acetoxy-2, 4-dimethyl-m-dioxane and the like.

Examples of the anti-fading agent include a benzotriazole ultraviolet absorber, a phosphorus antioxidant and the like.

The method for producing the ink jet recording ink of the present invention includes the above-mentioned acid-neutralized product and a coloring agent in water, and if necessary, the coloring material, a wetting agent, a water-soluble solvent, and a surface tension adjusting agent. And a method of appropriately adding and mixing a viscosity modifier, a fungicide, a preservative, an anti-fading agent and the like. Water in the ink is the balance, and its content is not particularly limited.

The viscosity of the ink thus obtained (2
5 ° C.) is preferably 1.2 to 30 mPa · s from the practical viewpoint used in the ink jet system. The solid content concentration (here, the solid content concentration means the concentration of components other than water) is preferably 50% by weight or less. Further, the pH of the ink can be varied widely, but precipitation may occur depending on the type of the above-mentioned agent added to the ink.

The ink having the above-described structure has excellent ozone resistance and excellent ejection characteristics in an ink jet system, such as no scorching in a printer head or clogging in a nozzle.

[0067]

EXAMPLES In the following examples and parts and percentages are by weight unless otherwise specified.

Production Example 1 (Preparation of Coloring Material 1) In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, 20 parts of methyl ethyl ketone as a polymerization solvent, and Table 1 in the column of initially charged monomer And the polymerization chain transfer agent described in (1) above 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 Table 1, 60 parts of methyl ethyl ketone, and 0.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) were sufficiently added. It was charged after 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. 2 hours after dropping, 2,2 '
A solution obtained by dissolving 0.1 part of -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 to obtain a copolymer solution.

A part of the obtained copolymer solution was removed under reduced pressure.
It was dried at 105 ° C. for 2 hours and isolated by completely removing the solvent. The molecular weight was measured by gel permeation chromatography using polystyrene as a standard substance and tetrahydrofuran as a solvent, and was found to be 10,000 as the weight average molecular weight. .

Further, 33.4 parts of an oily dye shown in Table 1 and 1000 parts of acetone were added to the obtained copolymer solution to completely dissolve it, and 100 parts of a 30% aqueous solution of a base shown in Table 1 was added under stirring. Partially neutralize the salt-forming groups in the copolymer and ion-exchange water 15
After adding 00 parts, methyl ethyl ketone and acetone were completely removed under reduced pressure at 60 ° C., and further concentrated by removing a part of water to obtain a coloring material 1 having a solid concentration of 20% by weight.

[0071]

[Table 1]

Examples 1 to 7 and Comparative Example 1 After the ink raw materials were added so as to have the compositions shown in Table 2,
The mixture was stirred and mixed for 0.5 hour or more, and each raw material was dissolved in water. Subsequently, the mixture was filtered under pressure through a membrane filter having an opening of 1.2 μm (manufactured by Millipore Co., Ltd.) to obtain an ink for inkjet recording.

The ink thus obtained was applied to plain paper (manufactured by Canon Inc., trade name: PB-paper) and glossy paper (manufactured by Canon Inc., BJC-430J) by an ink jet printer (manufactured by Canon Inc.). The product was printed on glossy photo paper GP301) to obtain a printed product. Using the obtained printed matter, the characteristics of the ink were evaluated by the following methods.

The printed state of the ink was examined by visually evaluating the printed matter of plain paper. In the table, “◎” is very good;
“○” indicates good; “△” indicates blurring (nozzle clogging); “×” indicates printing failure (nozzle clogging or scorching of the printer head).

With respect to the ozone resistance of the ink, the printed matter of plain paper and glossy paper was placed in an ozone atmosphere for one hour, and the color difference between immediately after printing and color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd.) was measured. From each, the ozone resistance of the paper was evaluated. In the table, “◎” is very good (no change);
"O" indicates good (almost no change); "X" indicates poor (significant discoloration and fading).

Table 2 shows the evaluation results.

[0077]

[Table 2]

From the results shown in Table 2, the inks obtained in Examples 1 to 7 are all compared with the ink obtained in Comparative Example 1.
Since the printing state is good, there is no nozzle clogging or scorching of the printer header, and it can be seen that plain paper and glossy paper are also excellent in ozone resistance.

[0079]

By using the ink for ink jet recording of the present invention, an excellent effect of obtaining a printed matter having excellent ozone resistance and being free from scorching in a printer head and clogging in a nozzle is obtained. You.

Claims (4)

[Claims] 1. An ink jet recording ink comprising an acid neutralized compound. 2. The ink according to claim 1, wherein the acid constituting the acid neutralized product is a polyvalent acid. 3. The ink according to claim 1, wherein the base constituting the acid neutralized product is an amine. 4. The ink according to claim 1, wherein the content of the acid-neutralized product in the ink is 0.1 to 30% by weight.