JP2001311021A - ink - Google Patents

Abstract

(57) [Problem] To provide an ink having weather resistance, excellent in water resistance, fixing property, and drying property, and particularly suitable for inkjet. A non-aqueous solvent contains at least a colorant, a photopolymerizable monomer, a photopolymerization initiator, and a resin soluble in a non-aqueous solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink, particularly to an ink suitable for ink-jet printing, and more particularly to an ink having excellent fixability, weather resistance, water resistance and quick drying property.

[0002]

2. Description of the Related Art Conventionally, as an ink-jet ink, there has been known an ink in which various water-soluble dyes are dissolved in an aqueous liquid as described in Japanese Patent Application Laid-Open No. 55-65269. .

However, the ink using the water-soluble dye as described above has a problem in weather resistance of a recorded image because the dye has poor weather resistance. That is, when the image is exposed to sunlight, fluorescent light, light from a projector, or the like, the image has a defect that the image becomes unreadable, disappears, or fades.

As a form for solving the drawback of poor weather resistance, for example, as described in JP-B-56-18623 and JP-A-4-18463, those using water-dispersible pigments are known. Are known.

[0005] However, inks using pigments are improved in weather resistance, but generally have the disadvantages of poor fixability and poor storage stability of the ink due to sedimentation of the pigment.

[0006] In order to solve this drawback, an ink to which a resin is added is known as an ink having fixability. However, when a resin is contained in the ink, there is a problem in that the head is clogged with the resin when the solvent in the ink evaporates or the viscosity of the ink is increased, so that ejection is difficult. Furthermore, the resin used here is water-soluble,
Alternatively, many of them are hydrophilic and have a problem in water resistance of a recorded image.

As a method for solving these problems, for example, as described in JP-A-7-224241, a method using a water-soluble monomer which solidifies upon application of energy and a water-soluble initiator is known. Are known. Although water resistance is expected to be improved by this, there are few types of initiators with particularly high sensitivity due to the restriction that the monomers and initiators used are water-soluble. Therefore, it has been difficult to show good fixation with low energy to the ink to which the pigment is added.

As still another embodiment, for example, Japanese Patent Application Laid-Open
As described in JP-A-48922, there is known an ink in which a radiation-curable macromer is contained in an emulsion state in an ink.

According to this embodiment, the range of choice of the monomer and the initiator is widened, but there is a problem in drying property.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet ink which has weather resistance, and is excellent in water resistance, fixability and drying property.

[0011]

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and the invention according to claim 1 provides at least a colorant and a photopolymerizable monomer in a non-aqueous solvent. An ink comprising a photopolymerization initiator and a resin soluble in a non-aqueous solvent.

The invention according to claim 2 is the ink according to claim 1, wherein the resin soluble in the non-aqueous solvent is an acrylic resin.

The invention according to claim 3 is the ink according to claim 1 or 2, wherein the colorant is a pigment.

According to a fourth aspect of the present invention, there is provided the ink according to the third aspect, wherein the pigment has an average particle diameter of 10 nm to 200 nm.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The pigment used in the present invention may be any pigment that can be dispersed in a solvent, and known organic or inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, quinacridone pigments,
Organic pigments such as anthraquinone pigments, perylene pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, dioxazine pigments, metal complex pigments, and fluorescent pigments, and barium sulfate, barium carbonate, alumina white, and titanium oxide Inorganic pigments such as iron oxide pigments and carbon black can be used, but are not limited thereto. The pigments may be used alone or in combination.

The particle diameters of these pigments are determined in consideration of the prevention of nozzle clogging, the coloring property, the transparency, and the dispersion stability of the ink over time because the produced ink is used in an ink jet system. Then, the smaller the particle size, the better the average particle size is 10 nm to 200 nm, and the maximum particle size is preferably 500 nm or less.

As the acrylic resin, about 3 to 5 kinds of monomers are selected from alkyl acrylates or alkyl methacrylates such as acrylic acid, methacrylic acid, methyl acrylate and methyl methacrylate, cyclic acrylates or methacrylates, hydroxyethyl acrylates and methacrylates. Using a molecular weight of 500
It is general to use a resin synthesized to about 0 to 100,000, but the resin is not limited to these.

As the photopolymerizable monomer, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, cyclohexyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, nonylphenyl carbitol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) Acrylate, 2-ethylhexyl carbitol (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylamide, vinyl acetate, N-hydroxymethyl (meth) acrylamide, diethylene glycol di (meth) acrylate,
Polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, styrene, vinyl acetate, various acrylates, various methacrylates, acrylonitrile , Dipentaerythritol hexa (meth) acrylate, tricyclodecanyl (meth) acrylate, dipentaerythritol hexa (meth) acrylate caprolactone adduct hexa (meth) acrylate, melamine (meth) acrylate, epoxy (meth) acrylate In addition to polymers and the like, polyester acrylate, urethane acrylate and the like can be mentioned. These may be used alone or in various mixtures. In particular, it is preferable that the main component of the photopolymerizable monomer contains at least one of polyol polyacrylate and polyester acrylate. In the description of (meth) acrylic acid and the like, “(meth)”
In this specification, it means either acrylic acid or methacrylic acid, and the same applies to the other.

Examples of the photoinitiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1one, -Hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1- (4-
Acetophenone-based photoinitiators such as morpholinophenyl) -butan-1-one; benzoin-based, benzophenone-based photoinitiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; benzophenone;
Benzoylbenzoic acid, methyl benzoylbenzoate, 4-
Phenylbenzophenone, hydroxybenzophenone,
Benzophenone-based photoinitiators such as acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, thioxanthone, 2-chlorothioxanthone,
Thioxanthone photoinitiators such as -methylthioxanthone, isopropylthioxanthone and 2,4-diisopropylthioxanthone; 2,4,6-trichloro-s-triazine; 2-phenyl-4,6-bis (trichloromethyl ) -S-Triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine , 2-Pipenyl-4,6-bis (trichloromethyl) -s-triazine, 2,4-
Bis (trichloromethyl) -6-styryl s-triazine, 2- (naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxy-
Naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2,4-trichloromethyl-
Compounds such as triazine photoinitiators such as (piperonyl) -6-triazine and 2,4-trichloromethyl (4′-methoxystyryl) -6-triazine and compounds such as carbazole photoinitiators and imidazole photoinitiators are used. Can be These may be used alone or in combination of two or more. In particular, when the main component of the initiator is a triazine-based compound, the sensitivity is good and fixing can be performed with low energy.

As sensitizers, α-acyloxime esters, acylphosphine oxides, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone, 4,4′-diethyl Isophthalophenone, 3,
Compounds such as 3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone and 4,4′-diethylaminobenzophenone can also be used.

Examples of the non-aqueous solvent include cyclohexanone, ethyl cellosolve acetate, butyl cellosolve acetate, 1-methoxy-2-propyl acetate,
Diethylene glycol dimethyl ether, ethylbenzene, ethylene glycol diethyl ether, xylene,
Ethyl cellosolve, methyl-n amyl ketone, propylene glycol monomethyl ether toluene, methyl ethyl ketone, ethyl acetate, methanol, ethanol, isopropyl alcohol, butanol, isobutyl ketone,
A petroleum-based solvent and the like can be mentioned, and these are used alone or as a mixture.

The ink-jet ink of the present invention is usually prepared as follows. First, a pigment is dispersed together with an acrylic resin and a solvent, or the pigment is mechanically kneaded with a transparent resin in advance, and then a solvent or a resin solution is added and dispersed. The pigment and the resin are blended at a solid content ratio of 1: 4 to 10: 1.

For dispersing the pigment in the resin, various dispersing means such as a three-roll mill, a two-roll mill, a sand mill, a ball mill, and a kneader can be used. In order to improve the dispersion, a dispersant may be added as necessary.

As the dispersant, anionic, nonionic, cationic, amphoteric activators, polymer dispersants and the like are used. Examples of anionic surfactants include alkyl sulfate salts, fatty acid salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, polyoxyethylene alkyl ether salts, and formalin naphthalene sulfonic acid. Condensates and the like. Examples of the nonionic activator include polyoxyethylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, glycerin fatty acid ester, silicone type, fluorine type and the like. Examples of the cationic activator include a quaternary ammonium salt and an alkylamine salt. Examples of amphoteric surfactants include dimethylalkyl lauryl betaine, alkyl glycine, imidazolinium betaine and the like. In practice, these dispersants are used alone or as a mixture.

Although the amount of the dispersant added is not particularly limited, it is generally 0.1 to 50 parts by mass of the pigment.

After the pigment and the resin are dispersed, a photopolymerizable monomer and a photoinitiator are added, and the mixture is adjusted by a method such as dilution with a solvent so as to have a viscosity suitable for ink-jet ink. The addition amount of the photopolymerizable monomer is generally 10 to 200 parts by mass based on the pigment, and the addition amount of the photoinitiator is generally 0.1 to 50 parts by mass based on the photopolymerizable monomer.

The fixing of the ink of the present invention is performed as follows. That is, the ink discharged from the inkjet head is absorbed by the solvent of the ink on the recording medium or dried by heating, and then is given energy by ultraviolet rays or electron beams. With this energy, the photopolymerizable monomer is polymerized and cured, and the acrylic resin is cross-linked with the polymerization, and the pigment is fixed on the recording medium. Therefore, an image having excellent water resistance can be obtained.

Further, according to the ink of the present invention, the energy required for polymerization and curing of the photopolymerizable monomer is 100 to 2
It may be about 00 mJ / cm ^2, which means low energy consumption.

In addition, if necessary, a pH adjuster, an antioxidant, a fungicide, an antifoaming agent and the like can be added.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments. <Example 1> 10 parts by mass of a phthalocyanine-based blue pigment, 10 parts by mass of an acrylic resin, 0.4 parts by mass of a polymer dispersant (manufactured by Zeneca: Solsperse 20000), cyclohexanone 7
9.6 parts by mass were mixed and dispersed in a sand mill for 3 hours to obtain a pigment dispersion (A).

25 parts by mass of pigment dispersion (A), 5 parts by mass of NK ester ATMPT (manufactured by Shin-Nakamura Chemical), 0.70 parts by mass of Irgacure 907 (manufactured by Ciba-Geigy), Kayacure DETX (Nippon Kayaku Co., Ltd.) 0.70 parts by mass)
Kaya Cure EPA (manufactured by Nippon Kayaku Co., Ltd.) 0.40 parts by mass,
After sufficiently mixing and dissolving 68.2 parts by mass of cyclohexanone, 1
Filtration through a micron and subsequently a 0.4 micron membrane filter gave an inkjet ink.

This ink was recorded on coated paper using an ink jet printer (HG5130, manufactured by Seiko Epson Corporation), and then irradiated with ultraviolet rays having an irradiation intensity of 100 mJ / cm ² . The recorded image was excellent in water resistance, solvent resistance, and adhesion. Even after exposure to a fluorescent lamp for three months, the density of the image did not change, and an image excellent in weather resistance was obtained.

Example 2 10 parts by mass of a carbon black pigment, 10 parts by mass of an acrylic resin, 0.4 parts by mass of a polymer dispersant (manufactured by Zeneca: Solsperse 20000) and 79.6 parts by mass of cyclohexanone were mixed. The mixture was dispersed in a sand mill for 3 hours to obtain a pigment dispersion (A).

25 parts by mass of the pigment dispersion (A), 5 parts by mass of NK ester ATMPT (manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.70 parts by mass of Irgacure 907 (manufactured by Ciba-Geigy), Kayacure DETX (Nippon Kayaku Co., Ltd.) 0.70 parts by mass)
Kaya Cure EPA (manufactured by Nippon Kayaku Co., Ltd.) 0.40 parts by mass,
After sufficiently mixing and dissolving 68.2 parts by mass of cyclohexanone, 1
Filtration through a micron and subsequently a 0.4 micron membrane filter gave an inkjet ink.

This ink was recorded on coated paper using an ink jet printer (HG5130, manufactured by Seiko Epson Corporation), and then irradiated with ultraviolet rays having an irradiation intensity of 200 mJ / cm ² . The recorded image was excellent in water resistance, solvent resistance, and adhesion. Even after exposure to a fluorescent lamp for three months, the density of the image did not change, and an image excellent in weather resistance was obtained.

[0037]

The ink-jet ink of the present invention uses an acrylic resin and a photopolymerizable monomer as a fixing material for a pigment which is a colorant. The pigment is fixed on the recording medium. By using an initiator having particularly high sensitivity, fixing can be performed with low energy, and energy consumption is low.

The obtained recorded image is excellent in water resistance and solvent resistance because the resin is in a crosslinked state. Also,
Since the pigment is used, the weather resistance is good.

Furthermore, since a non-aqueous solvent is used, it has excellent quick drying properties and can be used for various industrial purposes.

Claims (4)

[Claims] An ink characterized in that a non-aqueous solvent contains at least a colorant, a photopolymerizable monomer, a photopolymerization initiator, and a resin soluble in a nonaqueous solvent. 2. The ink according to claim 1, wherein the resin soluble in the non-aqueous solvent is an acrylic resin. 3. The ink according to claim 1, wherein the colorant is a pigment. 4. The pigment has an average particle size of 10 nm to 200 n.
The ink according to claim 3, wherein m is m.