JP2002371211A - Ink jet ink and recording method using the same - Google Patents

Abstract

(57) Abstract: An ink-jet ink having excellent water resistance and fixability, excellent ejection stability, and excellent ink storage stability even when a weather-resistant, non-ink-absorbing medium is used. And a recording method using the same. An inkjet ink in which at least a colorant and an emulsion resin are dispersed in an aqueous medium, wherein the colorant and the emulsion resin are electrostatically attracted. And a recording medium heated by using the inkjet ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet ink and a recording method.
It is excellent in weather resistance, water resistance, storage stability of ink, and ejection suitability.

[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, a fluorescent lamp, 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 have improved weatherability, but generally have poor fixability. Since pigments are basically insoluble in aqueous solvents and organic solvents, they have the disadvantage that the storage stability of the ink due to sedimentation of the pigment is poor.

[0006] In order to solve this drawback, an ink to which a resin is added is known as an ink having fixability. However, when the resin is contained in the ink, when the solvent in the ink evaporates, the head is clogged by precipitation of the resin,
Alternatively, there is a problem that ejection becomes difficult due to an increase in viscosity of the ink. Further, the resins used here are often water-soluble or hydrophilic, and have a problem in the water resistance of the recorded image.

As a method for solving these problems, for example, as described in JP-A-8-218016, a method using a monomer which is cured by an electron beam is known. However, the monomer used here is dissolved in the ink, and although water resistance increases after curing,
For ink-absorbing media, there is a problem that the ink penetrates into the media, so that the curing is insufficient, or that there is an odor of the monomer and it cannot be said that it is environmentally safe.

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 water resistance, the smell of the ink and the like are considerably improved, but there is a problem in the stability during storage of the ink due to the coalescence of the emulsion.

As another embodiment, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 8462, an ink composition combining a pigment and an emulsion resin is known. Here, it is said that the average particle size of the emulsion resin in the ink composition is 50 nm or less for stable ejection.

Further, for example, JP-A-9-208870 describes an ink composition in which the particle size of a pigment as a colorant and the particle size of an emulsion resin are each 200 nm or less.

According to these modes, however, although the ejection stability is improved, there are problems with the storage stability of the ink, the fixability of the recorded matter, and the water resistance.

[0013]

DISCLOSURE OF THE INVENTION The present invention is excellent in water resistance and fixing properties even when a medium having weather resistance and non-ink-absorbing properties is used, and excellent in ejection stability and storage stability of ink. An object of the present invention is to provide an inkjet ink and a recording method using the same.

[0014]

Means for Solving the Problems The present invention has been made to achieve the above object, and the invention according to claim 1 has at least a colorant and an emulsion resin dispersed in an aqueous medium. An ink-jet ink characterized in that the colorant and the emulsion resin are electrostatically attracted.

According to a second aspect of the present invention, there is provided a recording method comprising heating a recording medium recorded with the ink for ink jet recording.

[0016]

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

The colorant used in the present invention is preferably a pigment that is insoluble in water or an aqueous solvent, and may be any pigment that can be dispersed in water or an aqueous solvent. Known organic or inorganic pigments can be used. It is. 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 And inorganic pigments such as iron oxide pigments and carbon black.

According to a preferred embodiment of the present invention, among these pigments, those having good affinity for water are preferred. Specifically, carbon blacks such as furnace black, lamp black, acetylene black, and channel black (CI Pigment Black 7) are used for black.
Or copper, iron (CI Pigment Black 1)
1), metals such as titanium oxide, aniline black (C.I.
I. And organic pigments such as CI Pigment Black 1).

For other colors, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34,
35, 37, 42 (yellow iron oxide), 53, 55, 81,
83 (Disazo Yellow HR), 95, 97, 98, 1
00, 101, 104, 108, 109, 110, 11
7, 120, 138, 153, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I.
I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant Fast Scallet), 23, 31, 3
8, 48: 2 (permanent red 2B (Ba)), 4
8: 2 (permanent red 2B (Ca)), 48: 3
(Permanent red 2B (Sr)), 48: 4 (permanent red 2B (Mn)), 49: 1, 52: 2,
53: 1, 57: 1 (Brilliant Carmine 6B), 6
0: 1, 63: 1, 63: 2, 64: 1, 81 (rhodamine 6G lake), 83, 88, 101 (Bengara),
104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 17
0, 172, 177, 178, 179, 185, 19
0, 193, 209, 219, C.I. I. Pigment Violet 1 (rhodamine lake), 3, 5: 1, 16,
19 (quinacridone red), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56 , 60, 63, C.I. I.
Pigment Green 1, 4, 7, 8, 10, 17, 1
8, 36, etc. are used.

The particle size of these pigments is 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, a smaller one is preferable, and the average particle size is 10 nm to 200 nm and the maximum particle size is 50 nm.
Those having a thickness of 0 nm or less are preferably used.

Examples of the emulsion resin include polyacrylate, polymethacrylate, polyethylacrylate, styrene-butadiene copolymer,
Butadiene copolymer, acrylonitrile butadiene copolymer, chloroprene copolymer, crosslinked acrylic resin, crosslinked styrene resin, fluororesin, vinylidene fluoride, benzoguanamine resin, phenolic resin, polyolefin resin, cellulose, styrene-acrylate copolymer Coalesce, styrene-methacrylate copolymer, polystyrene, styrene-acrylamide copolymer, n-isobutyl acrylate, acrylonitrile, vinyl acetate, acrylamide, silicone resin, polyvinyl acetal, polyamide, rosin resin, polyethylene, polycarbonate, chloride Vinylidene resin, polyvinyl alcohol, cellulosic resin, epoxy resin, vinyl acetate resin, ethylene-vinyl acetate copolymer, vinyl acetate-acrylic copolymer, salt Vinyl resin, polyurethane, rosin ester, polyethylene wax, montan wax, alcohol wax, synthetic oxidized wax, α-olefin-maleic anhydride copolymer, carnauba wax and other animal and plant waxes, lanolin, paraffin wax, microcrystalline wax, etc. However, the present invention is not limited to this.

In order to prevent nozzle clogging, these resins only dry at room temperature and do not form a film.
When the solvent is removed at a temperature of T or more, it is desirable to form a water-resistant film.

The smaller the particle size of the emulsion resin, the smaller the particle size in consideration of the prevention of nozzle clogging and the stability of the ink over time because the produced ink is used in an ink jet system. Preferably
Average particle size is 10 nm to 200 nm, maximum particle size is 500 n
m or less is preferable.

Further, the particle size of the emulsion resin is preferably smaller than the particle size of the colorant.

In the present invention, the colorant and the emulsion resin retain their electric charges on the particle surface, and are attracted electrostatically because their polarities are opposite. Since the particle size of the emulsion resin is smaller than the particle size of the colorant and has a charge having the opposite polarity, the emulsion resin easily covers around the colorant in the ink. Therefore, sedimentation of the coloring agent is suppressed, and a more stable ink can be prepared.

The preparation of the ink is carried out by mixing a pigment dispersion in which a colorant is dispersed together with a dispersant in an aqueous medium, and an emulsion resin. The mixing ratio is preferably such that the emulsion resin uniformly covers the periphery of the colorant, and is determined by the particle size of the colorant and the emulsion resin.

As the dispersant, anionic, nonionic, cationic, amphoteric activators, polymer dispersants and the like are used. Examples of anionic surfactants include alkyl sulfates, fatty acid salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, polyoxyethylene alkyl ether salts, and naphthalene sulfonic acid formalin. 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 50.0 parts by mass of the colorant.

The charge on the surface can be stabilized by adding a generally known charge control agent such as an aliphatic metal salt and a quaternary ammonium salt in addition to the dispersant. In this case, the colorant and the emulsion resin are charged to opposite polarities.

The dispersion of the colorant is performed using a disperser such as a homogenizer, a paint shaker, a ball mill, and a sand mill.

As the aqueous medium, in addition to water, those which can be mixed with water can be appropriately added. For example, alkyl alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, ethylene glycol, propylene glycol, butylene glycol, 1, 2, 6,
-Hexanetriol, alkylene glycols such as diethylene glycol, polyethylene glycol, polyalkylene glycols such as polypropylene glycol,
Ethers such as tetrahydrofuran and dioxane, amides such as dimethylformamide and dimethylacetamide, and lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol monomethyl ether, diethylene glycol methyl ether and triethylene glycol methyl ether can be used.

In addition, if necessary, a pH adjuster such as potassium dihydrogen phosphate and disodium hydrogen phosphate, an antioxidant, a fungicide, an antifoaming agent and the like can be added.

A hydrophilic, high-boiling, low-volatile solvent can be added to the ink of the present invention in order to provide effects such as nozzle clogging prevention, moisture retention and dispersion stability. Examples of the hydrophilic high-boiling-point low-volatile solvent used in the present invention include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol, and polypropylene glycol. Polyhydric alcohols are used or their monoetherified, dietherified, esterified,
For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Diethylene glycol monobutyl ether and the like are used, and N-methyl-2-pyrrolidone, 1.3-dimethylimidazolidinone, monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, diethanolamine, Nn-butyl Nitrogen-containing organic solvents such as diethanolamine, triisopropanolamine and triethanolamine are used.

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 aqueous medium of the ink on the recording medium or dried by evaporation, and then the colorant is fixed by heating.

By this heating, the emulsion resin uniformly covers the periphery of the colorant, the colorant is strongly fixed on the recording medium, and water resistance is imparted. Fixing by heating is an effective means particularly when recording on a non-absorbable recording medium. In the case of recording on an absorptive recording medium, this heating step is not always necessary.

The heating is performed at a temperature not lower than the minimum film forming temperature of the emulsion resin. Preferably, it is 10 min.
The heating is preferably performed at a temperature higher by about ℃, and more preferably by heating at a temperature higher by about 20 ℃, the water resistance is further improved.

The heating means is not particularly limited.
The heating may be started after the ink droplet lands on the recording medium, or may be recording on a pre-heated recording medium.

In the present invention, since the emulsion resin is electrostatically attracted to the surface of the colorant, it is possible to effectively cover the periphery of the colorant without gaps, thereby improving the water resistance. . Further, since the amount of the emulsion resin to be added can be reduced, the viscosity of the ink can be suppressed low, and more stable ejection can be performed.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments. <Example 1> Phthalocyanine blue pigment (average particle size: 15
0 nm) 10 parts by weight, ethylene glycol 20 parts by weight,
5 parts by weight of glycerin, 1 part by weight of a nonionic active agent (manufactured by Kao: Emulgen 109P), a polymer dispersant (manufactured by Zeneca:
10 parts by weight of Solsperse 20000), 2 parts by weight of an anionic surfactant and 57 parts by weight of water were mixed and dispersed in a sand mill for 3 hours to obtain a pigment dispersion (A) in which the pigment was negatively charged.

To 50 parts by mass of the pigment dispersion (A), a positively charged emulsion resin of vinyl acetate-acrylic copolymer (average particle size: 50 nm, solid content: 40%) 12.5
Parts by weight and 37.5 parts by weight of water were mixed and filtered through a membrane filter of 1 micron followed by a 0.4 micron membrane to obtain an inkjet ink.

Using an ink jet printer (MJ810C, manufactured by Seiko Epson Corporation),
After recording on a T film, the film was heated and dried at 90 ° C. for 5 minutes. The recorded image is excellent in water resistance, solvent resistance and fixability, and there is no change in image density even after exposure to a fluorescent lamp for three months.
An image having excellent weather resistance was obtained.

Example 2 10 parts by weight of carbon black pigment (average particle size: 170 nm), ethylene glycol 2
0 parts by weight, 5 parts by weight of glycerin, 1 part by weight of a nonionic activator (manufactured by Kao: Emulgen 109P), 2 parts by weight of an anionic activator, polymer dispersant (manufactured by Zeneca: Solsperse 27)
000) and 10 parts by weight of water and 57 parts by weight of water were mixed and dispersed in a sand mill for 3 hours to obtain a pigment dispersion (A) in which the pigment was negatively charged.

11. 50 parts by mass of the pigment dispersion (A) is a positively charged emulsion resin of a styrene-methacrylic acid copolymer (average particle size: 45 nm, solid content: 40%)
5 parts by weight and 37.5 parts by weight of water were mixed and filtered through a 1 micron, then 0.4 micron membrane filter,
An inkjet ink was obtained.

The dispersion of this ink was stably maintained for 6 months or more. This ink was recorded on a PET film using an inkjet printer (manufactured by Seiko Epson Corporation: MJ810C) and then dried by heating at 90 ° C. for 5 minutes. The recorded image was excellent in water resistance, solvent resistance, fixability, and fluorescence. After exposure to the light for three months, there was no change in the density of the image,
An image having excellent weather resistance was obtained.

Comparative Example 1 The same pigment dispersion (A) as in Example 2 (average particle diameter of pigment: 130 nm) was added to 50 parts by mass.
Negatively charged emulsion resin of styrene-methacrylic acid copolymer (average particle size: 45 nm, solid content: 40
%) And 37.5 parts by weight of water were mixed and filtered through a membrane filter of 1 micron followed by a 0.4 micron membrane to obtain an inkjet ink.

Using an ink jet printer (MJ810C, manufactured by Seiko Epson Corporation),
After recording on a T film, the film was heated and dried at 90 ° C. for 5 minutes. Although the recorded image was excellent in weather resistance, it was insufficient in fixability, so that the image had insufficient water resistance and solvent resistance.

[0047]

According to the ink jet ink of the present invention, an emulsion resin is used as a fixing material for a colorant.
The emulsion resin particles and the colorant particles are electrostatically attracted.

Since the particle size of the emulsion resin is smaller than the particle size of the colorant, the emulsion resin is easily covered around the colorant in the ink, and the sedimentation of the colorant is suppressed, so that a more stable ink can be prepared. it can. Also,
Since the amount of the emulsion resin to be added can be reduced, the viscosity of the ink can be suppressed low, and more stable ejection can be performed.

In the present invention, the recording medium on which the ink has been recorded is heated. Because the particle size of the emulsion resin is smaller than the particle size of the colorant and is electrostatically attracted,
The emulsion resin can cover the colorant without gaps. Therefore, by heating, the colorant is uniformly covered with the resin, water resistance is imparted, and the colorant is strongly fixed on the recording medium. Fixing by heating is an effective means especially for recording on a non-absorbing recording medium, and this recording step is not always necessary for recording on an absorptive recording medium.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA13 FC01 FC02 HA46 2H086 BA05 BA53 BA55 BA59 4J039 AB02 AB08 AB12 AD01 AD03 AD04 AD05 AD06 AD07 AD08 AD10 AD11 AD12 AD14 AD15 AE02 AE04 AE05 AE06 AE08 AE11 BA04 BA13 BA16 BA18 BA18 BA35 BA37 BC39 BC60 BE01 CA06 DA02 EA15 EA16 EA17 EA19 EA34 EA38 EA41 EA43 EA44 GA24

Claims (2)

[Claims] An ink-jet ink in which at least a colorant and an emulsion resin are dispersed in an aqueous medium, wherein the colorant and the emulsion resin are electrostatically attracted. ink. 2. A recording method comprising heating a recording medium recorded with the ink for ink jet recording.