JP7386115B2 - Inkjet ink set, printed matter manufacturing method, and printed matter - Google Patents

Description

The present invention relates to an inkjet ink set, a method for manufacturing printed matter, and a printed matter. More specifically, the present invention provides a printed matter that has a wide color gamut that can be expressed, has an excellent transparency of the inkjet image layer, does not easily damage the design formed on the base material, and easily maintains the desired design over a long period of time. The present invention relates to an inkjet ink set that can be produced, a method for manufacturing printed matter, and a printed matter.

In recent years, various inkjet ink sets including inkjet inks for producing printed materials with excellent weather resistance have been developed. Patent Document 1 discloses an inkjet ink set using an inorganic pigment.

Patent No. 6366669

The inkjet ink set described in Patent Document 1 contains an inorganic pigment. However, inkjet ink sets containing inorganic pigments have a narrow color gamut, making it difficult to produce prints with a wide color gamut. On the other hand, in prints obtained using organic pigments, certain hues (for example, yellow or red) tend to fade over time. As a result, it is difficult for the printed matter to maintain its desired design over a long period of time. Furthermore, for example, inkjet inks are often used to produce printed matter expressing silver-based or pearl-based designs. The silver design can be formed by applying a paint containing fine aluminum foil and decorating it with inkjet ink.

The present invention was made to solve these problems, and by using a specified pigment, it is possible to express a design with a wide color gamut, the inkjet image layer has excellent transparency, and the base material An inkjet ink set that does not easily damage a design formed in the design, prevents fading of only a predetermined hue from the resulting design, and easily maintains a desired design over a long period of time, a method for manufacturing a printed matter, and a print. The purpose is to provide something.

The inkjet ink set, printed product manufacturing method, and printed product of the present invention that solve the above problems mainly include the following configurations.

(1) The ink includes a yellow ink, a red ink, and a blue ink, and the yellow ink, the red ink, and the blue ink each contain a pigment, a binder resin, a dispersant, and a solvent, and the pigment The average particle diameter of C.I. is 120 to 250 nm, and the pigment in the yellow ink is C.I. I. Pigment Yellow 138, 150, 151, 154 and 184, and the pigment in the red ink is C. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. Pigment Violet 19, and the pigment in the blue ink includes at least one selected from the group consisting of C. I. An inkjet ink set containing at least one of Pigment Blue 15:3 and 15:4.

According to such a configuration, predetermined pigments are selected as pigments for the yellow ink, red ink, and blue ink. An ink set containing such ink can express designs with a wide color gamut. Furthermore, the selected predetermined pigments have similar weather resistance for each hue (yellow, red, blue). As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

(2) The yellow ink has an average light transmittance of 50 to 90% at a wavelength of 530 to 580 nm of the inkjet image layer obtained by applying the yellow ink to a film thickness of 20 μm, and the red ink has a film thickness of 20 μm. The inkjet image layer obtained by coating the inkjet image layer has an average light transmittance of 50 to 90% at a wavelength of 630 to 680 nm, and the blue ink is coated to a thickness of 20 μm. The inkjet ink set according to (1), which has an average light transmittance of 50 to 90% at a wavelength of 780 to 830 nm.

According to such a configuration, the resulting inkjet image layer has high transparency. As a result, the resulting print does not easily damage the design formed on the base material.

(3) The yellow ink, the red ink, and the blue ink are each coated to a thickness of 20 μm, and the resulting inkjet image layer has an average light transmittance of 20% or less at a wavelength of 280 to 380 nm. The inkjet ink set described in (1) or (2).

According to such a configuration, the resulting inkjet image layer has a low transmittance in the ultraviolet light region. As a result, the resulting prints have pigments in the inkjet image layer that are less likely to be damaged and have excellent weather resistance.

(4) The yellow ink is coated to have a film thickness of 20 μm, so that the resulting inkjet image layer satisfies b*≧65 in the L*a*b* color system, and the red ink has a film thickness of 20 μm. The inkjet image layer obtained by coating the blue ink satisfies a*≧40 in the L*a*b* color system, and the inkjet image layer obtained by coating the blue ink to a film thickness of 20 μm satisfies L*a The inkjet ink set according to any one of (1) to (3), which satisfies b*≦-35 in the *b* color system.

According to such a configuration, the ink set has the advantage that the obtained printed matter has excellent coloring properties.

(5) The inkjet ink set according to any one of (1) to (4), wherein the binder resin is a fluororesin.

According to such a configuration, the resulting printed matter exhibits better weather resistance.

(6) The inkjet ink set according to (5), wherein the fluororesin is a copolymer of fluoroethylene and a vinyl monomer.

According to such a configuration, the resulting printed matter exhibits better weather resistance.

(7) A printed product comprising a printing step of applying ink to a substrate by an inkjet method using the inkjet ink set according to any one of (1) to (6), and a drying step of drying the ink. manufacturing method.

According to such a configuration, the resulting print can express a design with a wide color gamut. Further, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is easily maintained over a long period of time.

(8) comprising a base material and an inkjet image layer on which ink constituting an ink set is applied, the inkjet image layer comprising a yellow ink, a red ink and a blue ink, the yellow ink; The red ink and the blue ink each contain a pigment, a binder resin, and a dispersant, and the pigment has an average particle diameter of 120 to 250 nm, and the pigment in the yellow ink contains C.I. I. Pigment Yellow 138, 150, 151, 154 and 184, and the pigment in the red ink is C. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. Pigment Violet 19, and the pigment in the blue ink includes at least one selected from the group consisting of C. I. A printed matter containing at least one of Pigment Blue 15:3 and 15:4.

According to such a configuration, the printed matter can express a design with a wide color gamut. Further, in the printed matter, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is easily maintained over a long period of time.

According to the present invention, by using a predetermined pigment, a design with a wide color gamut can be expressed, and only a predetermined hue can be prevented from fading from the obtained design, and the desired color can be maintained for a long period of time. It is possible to provide an inkjet ink set, a method for manufacturing a printed matter, and a printed matter in which the design of the printed matter is easily maintained.

<Inkjet ink set>
An inkjet ink set (hereinafter referred to as an ink set) according to an embodiment of the present invention includes yellow ink, red ink, and blue ink. The yellow ink, red ink, and blue ink each contain a pigment, a binder resin, a dispersant, and a solvent. The average particle size of the pigment is 120 to 250 nm. The pigment in the yellow ink is C. I. Pigment Yellow 138, 150, 151, 154 and 184. The pigment in the red ink is C.I. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. Contains at least one species selected from the group consisting of Pigment Violet 19. The pigment in the blue ink is C.I. I. Pigment Blue 15:3 and 15:4. In the ink set of this embodiment, predetermined pigments are selected as pigments in yellow ink, red ink, and blue ink. An ink set containing such ink can express designs with a wide color gamut. Furthermore, the selected predetermined pigments have similar weather resistance for each hue (yellow, red, blue). As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time. Each will be explained below.

The ink set of this embodiment includes yellow ink, red ink, and blue ink as inks. Note that the ink set may include inks of other hues (for example, black ink, colored inks, etc.).

(yellow ink)
The yellow ink includes a pigment (yellow pigment), a binder resin, a dispersant, and a solvent.

・Yellow pigment Yellow pigment is C. I. Pigment Yellow 138, 150, 151, 154 and 184. Among these, yellow pigments are more resistant to fading and have a similar degree of fading, that is, weather resistance, to other inks; therefore, C.I. I. Pigment Yellow 150, 151 and 184. A yellow pigment may be used in combination.

The content of yellow pigment in the yellow ink is not particularly limited. For example, the content of the yellow pigment in the yellow ink is preferably 1% by mass or more, more preferably 1.5% by mass or more. Further, the content of the yellow pigment in the yellow ink is preferably 15% by mass or less, more preferably 10% by mass or less. When the content of the yellow pigment is within the above range, the resulting ink set can easily express designs with a wider color gamut. Additionally, the yellow pigment selected has similar weather resistance to other ink pigments. As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

- Binder resin The binder resin is contained, for example, to adjust the viscosity of the ink, and to adjust the hardness and shape of the resulting print.

The type of binder resin is not particularly limited. For example, binder resins include epoxy resin, diallyl phthalate resin, silicone resin, phenolic resin, unsaturated polyester resin, polyimide resin, polyurethane resin, melamine resin, urea resin, ionomer resin, ethylene ethyl acrylate resin, acrylonitrile acrylate styrene. Copolymer resin, acrylonitrile styrene resin, acrylonitrile chlorinated polyethylene styrene copolymer resin, ethylene vinyl acetate resin, ethylene vinyl alcohol copolymer resin, acrylonitrile butadiene styrene copolymer resin, vinyl chloride resin, chlorinated polyethylene resin, polyvinylidene chloride resin, Cellulose acetate resin, fluororesin, polyoxymethylene resin, polyamide resin, polyarylate resin, thermoplastic polyurethane elastomer, polyether ether ketone resin, polyether sulfone resin, polyethylene, polypropylene, polycarbonate resin, polystyrene, polystyrene maleic acid copolymer resin , polystyrene acrylic acid copolymer resin, polyphenylene ether resin, polyphenylene sulfide resin, polybutadiene resin, polybutylene terephthalate resin, acrylic resin, methacrylic resin, methylpentene resin, polylactic acid, polybutylene succinate resin, butyral resin, formal resin, polyvinyl Examples include alcohol, polyvinylpyrrolidone, ethyl cellulose, carboxymethyl cellulose, gelatin, and copolymer resins thereof. The binder resin may be appropriately selected in consideration of film strength, viscosity, residual viscosity of the inkjet ink, pigment dispersion stability, thermal stability, non-coloring property, water resistance, and chemical resistance. A binder resin may be used in combination.

Among these, the binder resin is preferably a fluororesin, acrylic resin, vinyl chloride resin, or silicone resin from the viewpoint of having excellent heat resistance and weather resistance. A fluororesin is preferable from the viewpoint of better weather resistance of the resulting printed product.

-Fluororesin The fluororesin is not particularly limited. For example, the fluororesin is preferably a copolymer of various fluorine-containing monomers and a vinyl monomer. Furthermore, among vinyl monomers, the fluororesin is more preferably a copolymer with a vinyl ether monomer.

The fluorine-containing monomer is preferably fluoroethylene, and examples thereof include tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, and the like. Among these, tetrafluoroethylene and chlorotrifluoroethylene are more preferable as the fluorine-containing monomer, since printed materials exhibiting excellent weather resistance can be obtained.

Examples of vinyl monomers include nonionic monoethylenically unsaturated monomers and difunctional vinyl monomers. Examples of nonionic monoethylenically unsaturated monomers include styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth)acrylamide, (meth)acrylic acid ester, and the like. (Meth)acrylic acid esters include methyl acrylate, methyl methacrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl methacrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, lauryl ( Examples include meth)acrylate, oleyl(meth)acrylate, palmityl(meth)acrylate, and stearyl(meth)acrylate. Examples of the difunctional vinyl monomer include divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, 1,3-butane-diol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

Vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether. di- or trivinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl Examples include monovinyl ether compounds such as ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

The copolymerization ratio of the fluorine-containing monomer and the vinyl monomer is not particularly limited. For example, the copolymerization ratio is fluorine-containing monomer:vinyl monomer=3 to 1:1 to 2 (weight ratio). When the copolymerization ratio is within this range, the resulting prints tend to exhibit excellent weather resistance. Note that the polymerization method is not particularly limited. For example, polymerization methods include solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization.

The resulting fluororesin may be any of alternating copolymers, block copolymers, random copolymers, and graft copolymers. Among these, the fluororesin is preferably an alternating copolymer of fluoroethylene and vinyl monomer. Prints containing such a fluororesin have even better weather resistance. In the present embodiment, an "alternating copolymer" means that the bond between a fluoroethylene unit and a vinyl monomer unit is the bond between a fluoroethylene unit and a fluoroethylene unit, and the bond between a vinyl monomer unit and a vinyl monomer unit. This means a copolymer containing much more bonds than the total number of bonds. Specifically, the alternating copolymer of this embodiment preferably contains 90 to 100 mol% of bonds between fluoroethylene units and vinyl monomer units. In addition, in this embodiment, the alternating copolymer may include a small number of random bonding portions or block bonding portions. Moreover, the above-mentioned bonds can be distinguished, for example, by ¹ H NMR measurements and ²⁹ Si NMR measurements. For the analysis method of alternating copolymerizability, reference may be made to, for example, Journal of Applied Polymer Science, Vol. 106, 1007-1013 (2007).

The fluororesin of this embodiment preferably has a solubility in diethylene glycol diethyl ether of 500 (g/L) or more, more preferably 1000 (g/L) or more, in terms of solid content. When the solubility of the ink in diethylene glycol diethyl ether is within the above range, reprecipitation of the fluororesin is less likely to occur over a long period of time, and the ejection stability during inkjet printing is better.

The fluororesin of this embodiment preferably has a hydroxyl value of 20 mgKOH/g or more, more preferably 30 mgKOH/g or more. Further, the hydroxyl value of the fluororesin is preferably 100 mgKOH/g or less, more preferably 80 mgKOH/g or less. When the hydroxyl value is within the above range, the ink has excellent curability and more excellent ejection stability during inkjet printing. When the hydroxyl value is less than 20 mgKOH/g, it tends to be difficult to react with the curing agent. On the other hand, if the hydroxyl value exceeds 100 mgKOH/g, the ink dispersion system tends to become unstable and the ejection stability tends to decrease. In this embodiment, the hydroxyl value represents the number of mg of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of the sample (solid content of the resin) is acetylated. This is a value measured by a method similar to the method described in JIS K 0070.

The fluororesin preferably has an acid value of 5 mgKOH/g or less, more preferably 4 mgKOH/g or less. When the acid value is 5 mgKOH/g or less, the ink has a stable dispersion system and excellent ejection stability. On the other hand, when the acid value exceeds 5 mgKOH/g, the dispersion system of the ink tends to become unstable and the ejection stability tends to decrease. In addition, in this embodiment, the acid value represents the mass (mg) of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample (solid content of the resin), and is This is a value measured by a method similar to the above method.

The weight average molecular weight (Mw) of the fluororesin is not particularly limited. For example, Mw is preferably 5,000 or more, more preferably 8,000 or more. Mw is preferably 50,000 or less, more preferably 40,000 or less. When Mw is within the above range, the fluororesin is easily dissolved in the solvent. Furthermore, the ink has improved drying properties and has excellent ejection stability during inkjet printing. Furthermore, the resulting printed matter has less stickiness on the surface and has excellent anti-blocking properties. When Mw is less than 5,000, the resulting printed matter tends to become sticky and the anti-blocking properties tend to decrease. On the other hand, when Mw exceeds 50,000, the solubility of the fluororesin tends to decrease, and the ejection stability of ink during inkjet printing tends to decrease. In the present embodiment, Mw is a value measured by, for example, GPC (gel permeation chromatography), and can be measured using a high-speed GPC device (manufactured by Tosoh Corporation, HLC-8120GPC).

- Acrylic resin Acrylic resin is not particularly limited. For example, the acrylic resin may be a polymer of acrylic ester (acrylate) or methacrylic ester (methacrylate). More specifically, acrylic resins include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; methyl methacrylate, and methacrylate. Methacrylic acid alkyl esters such as ethyl acid, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, etc. Hydroxy group-containing acrylic esters: Examples include polymers such as hydroxy group-containing methacrylic esters such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate. These may be used in combination.

The weight average molecular weight (Mw) of the acrylic resin is not particularly limited. For example, Mw is preferably 5,000 or more, more preferably 10,000 or more. Mw is preferably 100,000 or less, more preferably 50,000 or less. When Mw is within the above range, the ink containing such an acrylic resin has excellent ejection stability during inkjet printing.

- Vinyl chloride resin Vinyl chloride resin is not particularly limited. For example, vinyl chloride resins include copolymers of vinyl chloride and other monomers such as vinyl acetate, vinylidene chloride, acrylic acid, maleic acid, and vinyl alcohol. Among these, the vinyl chloride resin is preferably a copolymer (vinyl chloride-vinyl acetate copolymer) containing structural units derived from vinyl chloride and vinyl acetate.

The vinyl chloride-vinyl acetate copolymer can be obtained, for example, by suspension polymerization. The vinyl chloride-vinyl acetate copolymer preferably contains 70 to 90% by mass of vinyl chloride units. Within the above range, the vinyl chloride-vinyl acetate copolymer is stably dissolved in the ink, and therefore has excellent long-term storage stability. Further, the ink has excellent ejection stability.

In addition to vinyl chloride units and vinyl acetate units, the vinyl chloride-vinyl acetate copolymer may include other structural units as necessary. For example, other structural units include carboxylic acid units, vinyl alcohol units, hydroxyalkyl acrylate units, and the like. Among these, the other structural units are preferably vinyl alcohol units.

The number average molecular weight (Mn) of the vinyl chloride resin is not particularly limited. For example, Mn of the vinyl chloride resin is preferably 10,000 or more, more preferably 12,000 or more. Further, Mn is preferably 50,000 or less, more preferably 42,000 or less. Note that Mn can be measured by GPC, and can be obtained as a relative value in terms of polystyrene.

-Silicone resin Silicone resin is not particularly limited. For example, silicone resins include methyl-based straight silicone resin (polydimethylsiloxane), methylphenyl-based straight silicone resin (polydimethylsiloxane in which some of the methyl groups are replaced with phenyl groups), acrylic resin-modified silicone resin, and polyester resin. Examples include resin-modified silicone resin, epoxy resin-modified silicone resin, alkyd resin-modified silicone resin, and rubber-based silicone resin. These may be used in combination. Among these, the silicone resin is preferably methyl-based straight silicone resin, methylphenyl-based straight silicone resin, or acrylic resin-modified silicone resin.

The silicone resin may be dissolved in an organic solvent or the like. Examples of organic solvents include xylene and toluene.

The number average molecular weight (Mn) of the silicone resin is not particularly limited. For example, the Mn of the silicone resin is preferably 10,000 or more, more preferably 20,000 or more. Further, Mn is preferably 5,000,000 or less, more preferably 3,000,000 or less. Note that Mn can be measured by GPC, and can be obtained as a relative value in terms of polystyrene.

Returning to the overall description of the binder resin, the content of the binder resin in the ink is not particularly limited. For example, the binder resin preferably accounts for 1% by mass or more in the ink, more preferably 3% by mass or more, and even more preferably 5% by mass or more, in terms of solid content. Further, the binder resin content in the ink is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. When the content of the binder resin is less than 1% by mass, it is difficult to obtain desired performance as a binder, and image adhesion to the substrate tends to deteriorate. On the other hand, if the content of the binder resin exceeds 40% by mass, the viscosity of the ink increases and the ejection stability during inkjet printing tends to decrease.

Among them, when a fluororesin is included as the binder resin, the content of the fluororesin in the ink is not particularly limited. For example, in terms of solid content, the fluororesin content in the ink is preferably 2% by mass or more, and more preferably 5% by mass or more. Further, the content of the fluororesin in the ink is preferably 40% by mass or less, and more preferably 30% by mass or less. When the content of the fluororesin is 2% by mass or more, the ink tends to have excellent ejection stability during inkjet printing. On the other hand, when the content of the fluororesin exceeds 40% by mass, the viscosity of the ink increases, and the ejection stability during inkjet printing tends to decrease.

- Dispersant A dispersant is blended to disperse the above pigment. The dispersant is not particularly limited. For example, the dispersant may be an anionic surfactant, a nonionic surfactant, a polymer dispersant, or the like. A dispersant may be used in combination.

Anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, lignin sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, and polyesters. Examples include oxyethylene alkyl sulfate salts and substituted derivatives thereof.

Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl amine, glycerin fatty acid ester, oxyethylene oxy Examples include propylene block polymers and substituted derivatives thereof.

It is preferable that the polymeric dispersant has both an acid value and a base value, and the acid value is larger than the base value from the viewpoint of obtaining more stable dispersion characteristics. For example, polymer dispersants include the PB series manufactured by Ajinomoto Fine Techno Co., Ltd., the Hinoact series manufactured by Kawaken Fine Chemicals Co., Ltd., the Solsperse series manufactured by Nippon Lubrizol Co., Ltd., and the Kusumoto Kasei Co., Ltd. Examples include the DISPARLON series manufactured by ) and the Efka (registered trademark) series manufactured by BASF Japan Co., Ltd.

The content of the dispersant is appropriately determined depending on the type and content of the pigment to be dispersed. For example, the content of the dispersant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, based on 100 parts by mass of the pigment. Further, the content of the dispersant is preferably 150 parts by mass or less, more preferably 80 parts by mass or less, based on 100 parts by mass of the pigment. When the content of the dispersant is less than 5 parts by mass, the pigment tends to be difficult to disperse. On the other hand, if the content of the dispersant exceeds 150 parts by mass, raw material costs tend to increase and pigment dispersion tends to be inhibited.

-Solvent A solvent is added to the ink to dissolve the binder resin. The type of solvent is not particularly limited. Examples of the solvent include water, glycol ether solvents, acetate solvents, alcohol solvents, ketone solvents, ester solvents, hydrocarbon solvents, fatty acid ester solvents, aromatic solvents, and the like. Solvents may be used in combination. Among these, the solvent of the present embodiment preferably contains at least one of a glycol ether solvent and an acetate solvent. Glycol ether solvents and acetate solvents both have low viscosity and relatively high boiling points. Therefore, inks containing these as solvents have improved drying properties and better ejection stability during inkjet printing.

Glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono(iso)propyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, and propylene glycol. Monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n -Butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-propyl ether, triethylene glycol mono-n-butyl ether, tripropylene glycol monoethyl ether, tripropylene glycol mono-n-propyl Ether, tripropylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether , triethylene glycol butyl methyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether and the like.

Acetate solvents include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, ethylene glycol mono-sec-butyl ether acetate, Ethylene glycol monoisobutyl ether acetate, ethylene glycol mono-tert-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monoisopropyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol mono-n-butyl ether Acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol monoisobutyl ether acetate, propylene glycol mono-tert-butyl ether acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-ethoxybutyl acetate, 3-methyl -3-propoxybutyl acetate, 3-methyl-3-isopropoxybutyl acetate, 3-methyl-3-n-butoxyethyl acetate, 3-methyl-3-isobutoxybutyl acetate, 3-methyl-3-sec-butoxy alkylene glycol monoalkyl ether acetates such as butyl acetate, 3-methyl-3-tert-butoxybutyl acetate, ethylene glycol diacetate, diethylene glycol diacetate, triethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, Examples include tripropylene glycol diacetate.

The solvent of this embodiment preferably has a boiling point of 150°C or higher, more preferably 180°C or higher. Further, the boiling point of the solvent is preferably 300°C or lower, more preferably 280°C or lower. When the boiling point is within the above range, the resulting ink has improved drying properties and better ejection stability during inkjet printing. Furthermore, with ink, clear prints with little bleeding can be easily formed. If the boiling point of the solvent is less than 150° C., the ink tends to dry near the head nozzle, and the ejection stability tends to decrease. On the other hand, when the boiling point of the solvent exceeds 300° C., the ink becomes difficult to dry, and the drying process during the formation of printed matter tends to take a long time. In addition, the images in the obtained prints tend to bleed.

The content of the solvent is not particularly limited. For example, the amount of the solvent in the ink is preferably 25% by mass or more, more preferably 30% by mass or more. Further, the content of the solvent in the ink is preferably 95% by mass or less, and more preferably 90% by mass or less. When the content of the solvent is less than 25% by mass, the viscosity of the ink increases, and the ejection stability during inkjet printing tends to decrease. On the other hand, when the content of the solvent exceeds 95% by mass, the proportion of pigments and binder resins that can be added to the ink decreases, and it tends to be difficult to obtain desired color development and performance.

-Optional Components In addition to the pigment (yellow pigment), binder resin, dispersant, and solvent described above, the ink can contain arbitrary components well known in the field of inkjet inks. For example, optional components include a curing agent, a curing catalyst, a weather resistance improver (for example, an ultraviolet absorber, a light stabilizer, etc.), a slip agent (leveling agent), a polymerization accelerator, a polymerization inhibitor, a penetration enhancer, These include wetting agents (humectants), fixing agents, antifungal agents, preservatives, antioxidants, chelating agents, thickeners, etc.

- Hardening agent A hardening agent may be blended to harden the ink. The curing agent is not particularly limited. For example, the curing agent may include a carbodiimide curing agent, an aziridine curing agent, a metal chelate curing agent, an isocyanate curing agent, a melamine curing agent, an epoxy curing agent, an oxazoline curing agent, a urea curing agent, These include polyamine-based curing agents, polyethyleneimine-based curing agents, acrylamide-based curing agents, and the like. A curing agent may be used in combination. Among these, the curing agent preferably contains an isocyanate-based curing agent. Thereby, prints obtained using such ink have better weather resistance.

The isocyanate resin constituting the isocyanate curing agent may be any compound having two or more isocyanate groups in one molecule, and any of general-purpose, non-yellowing, and non-yellowing types may be used. Examples of general-purpose types include tolylene diisocyanate (TDI), isocyanurate which is a trimerized product of TDI, 4,4-diphenylmethane diisocyanate (MDI), and polymeric diphenylmethane diisocyanate (polymeric MDI). Examples of the non-yellowing type include xylylene diisocyanate (XDI) and the like. Examples of non-yellowing types include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), hydrogenated XDI, and hydrogenated MDI. Among these, the curing agent preferably contains a non-yellowing blocked isocyanate, and more preferably a non-yellowing blocked isocyanate having an isocyanurate structure. Ink containing such a curing agent has better curability. Further, by using such an ink, the resulting printed matter has even better weather resistance. Therefore, the printed matter tends to exhibit the desired color for a longer period of time.

The content of the curing agent is not particularly limited. Since it varies depending on the amount of binder resin added, etc., it cannot be determined uniquely. For example, the content of the curing agent in the ink is preferably 0.1% by mass or more, more preferably 1% by mass or more. Further, the content of the curing agent in the ink is preferably 20% by mass or less, more preferably 10% by mass or less. If the content of the curing agent is less than 0.1% by mass, it may not be able to react sufficiently with the binder resin, and the desired performance may not be obtained. On the other hand, if the content of the curing agent exceeds 20% by mass, there is a risk that the curing agent will be added excessively to the binder resin, and the weather resistance of the resulting printed product will tend to deteriorate.

・Curing catalyst Curing catalysts include organic acid salts, alcoholates, and chelate compounds of metals such as tin, titanium, zirconium, iron, antimony, bismuth, manganese, zinc, and aluminum; amines such as hexylamine and dodecylamine; hexylamine acetate , amine salts such as dodecylamine phosphate; quaternary ammonium salts such as benzyltrimethylammonium acetate; and alkali metal salts such as potassium acetate. More specifically, organic bismuth compounds such as bismuth octylate and bismuth neodecanoate, dibutyltin dilaurate, dibutyltin dioctylate, dimethyltin dineodecanoate, and organotin compounds such as stannath octoate, tetrabutyl titanate, tetraisopropyl titanate, and Examples include organic titanium compounds such as isopropoxybis(acetylacetone)titanium and diisopropoxybis(ethylacetoacetate)titanium. These may be used in combination. In this embodiment, the curing catalyst is preferably a tin-based compound, more preferably a dialkyltin-based compound such as dibutyltin dilaurate or dimethyltin dineodecanoate, and even more preferably dibutyltin dilaurate. When dibutyltin dilaurate is included as a curing catalyst, the resulting ink has excellent curability.

When a curing catalyst is blended, the content is not particularly limited. For example, the content of the curing catalyst in the ink is preferably 0.001% by mass or more, more preferably 0.01% by mass or more. Further, the content of the curing catalyst in the ink is preferably 5% by mass or less, more preferably 3% by mass or less. When the content of the curing catalyst is less than 0.001% by mass, there is a tendency that the performance as a curing catalyst is not sufficiently exhibited. On the other hand, when the content of the curing catalyst exceeds 5% by mass, the curability of the ink increases, and the ejection stability during inkjet printing tends to decrease.

-Weather resistance improver A weather resistance improver (for example, an ultraviolet absorber, a light stabilizer, etc.) is suitably contained in order to improve the weather resistance of a printed product.

The ultraviolet absorber is not particularly limited. For example, the ultraviolet absorber may be a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, a triazine derivative, a salicylic acid derivative, or the like. Benzotriazole UV absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'- Hydroxy-5'-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3 '-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-( 2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methacrylate) oxyethylphenyl)-2H-benzotriazole, 2-{(2'-hydroxy-3',3'',4'',5'',6''-tetrahydrophthalimidomethyl)-5'-methylphenyl}benzotriazole, etc. Illustrated. Benzophenone UV absorbers include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, and 2-hydroxybenzophenone. -4-dodecyloxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4 -Methoxy-5-sulfobenzophenone and the like are exemplified. The triazine derivative is 2-[4-{(2-hydroxy-3-dodecyloxy-propyl)oxy}-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5- triazine, 2-[4-{(2-hydroxy-3-tridecyloxy-propyl)oxy}-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-{4-(octyl-2-methylethanoate)oxy-2-hydroxyphenyl-4,6-{bis(2,4-dimethylphenyl)}-1,3,5-triazine, tris[2,4 , 6-[2-{4-(octyl-2-methylethanoate)oxy-2-hydroxyphenyl}]-1,3,5-triazine and the like. Examples of salicylic acid derivatives include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and p-(1,1,3,3-tetramethylbutyl) phenyl salicylate. Ultraviolet absorbers may be used in combination.

When an ultraviolet absorber is blended, the content is not particularly limited. For example, the content of the ultraviolet absorber in the ink is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. Further, the content of the ultraviolet absorber in the ink is preferably 10% by mass or less, more preferably 5% by mass or less. When the content of the ultraviolet absorber is within the above range, the weather resistance of the printed matter is likely to be improved.

The light stabilizer is not particularly limited. For example, the light stabilizer is a hindered amine light stabilizer. The hindered amine light stabilizers include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6- Tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1 -undecyloxy-2,2,6,6-tetramethyl-4-piperidyl)carbonate, tetrakis(2,2,6,6-tetramethyl-4-piperidylbutanetetracarboxylate, tetrakis(1,2,2 , 6,6-pentamethyl-4-piperidylbutane tetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl) di(tridecyl)-1,2,3,4-butane tetracarboxylate , bis(1,2,2,6,6-pentamethyl-4-piperidyl) di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6- Pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl- 4-piperidinol/diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/dibromoethane polycondensate, 1,6-bis(2,2 , 6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4 -piperidylamino)hexane/2,4-dichloro-6-tertiary octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2 , 2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis[2, 4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane , 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-ylaminoundecane, 1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-ylaminoundecane, Bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)-decanedioate and the like. A light stabilizer may be used in combination.

When a light stabilizer is blended, the content is not particularly limited. For example, the content of the light stabilizer in the ink is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. Further, the content of the light stabilizer in the ink is preferably 10% by mass or less, more preferably 5% by mass or less. When the content of the light stabilizer is within the above range, the weather resistance of the printed matter is likely to be improved.

Returning to the explanation of the ink as a whole, the viscosity of the ink is not particularly limited. For example, the viscosity of the ink is preferably 2 mPa·s or more, more preferably 5 mPa·s or more. Further, the viscosity is preferably 50 mPa·s or less, more preferably 30 mPa·s or less. When the viscosity is within the above range, the ink is less likely to cause ejection failure from the inkjet head and has excellent ejection stability. In this embodiment, the viscosity of the ink can be measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVB-20LT, rotor rotation speed 60 rpm). Note that the method for adjusting the viscosity within the above range is not particularly limited. For example, the viscosity can be adjusted by the amount of each component added and the type and amount of the solvent. The viscosity may be adjusted by using a viscosity modifier such as a thickener, if necessary.

The surface tension of the ink is not particularly limited. The surface tension of the ink at 25° C. is preferably 20 dyne/cm or more, more preferably 22 dyne/cm or more. Further, the surface tension of the ink at 25° C. is preferably 40 dyne/cm or less, more preferably 35 dyne/cm or less. When the surface tension is within the above range, the ink has excellent ejection stability. In this embodiment, the surface tension can be measured using a static surface tension meter (plate method) (manufactured by Kyowa Interface Science Co., Ltd., CBVP-A3).

(red ink)
The red ink includes a pigment (red pigment), a binder resin, a dispersant, and a solvent.

・Red pigment The red pigment is C. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. Contains at least one species selected from the group consisting of Pigment Violet 19. Among these, red pigments are more resistant to fading and have a similar degree of fading, that is, weather resistance, to other inks; therefore, C.I. I. Pigment Red 254, 264 is preferably included. A red pigment may be used in combination.

The content of red pigment in the red ink is not particularly limited. For example, the content of the red pigment in the red ink is preferably 1% by mass or more, more preferably 1.5% by mass or more. Further, the content of the red pigment in the red ink is preferably 15% by mass or less, more preferably 10% by mass or less. When the content of the red pigment is within the above range, the obtained ink set can easily express designs with a wider color gamut. In addition, the selected red pigment has similar weather resistance to other ink pigments. As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

Note that the binder resin, dispersant, solvent, and optional components contained in the red ink are the same as those described above in connection with the yellow ink. Therefore, explanation regarding these components will be omitted. Further, the physical properties of the red ink are similar to the physical properties of the ink described above in relation to the yellow ink.

(blue ink)
The blue ink includes a pigment (blue pigment), a binder resin, a dispersant, and a solvent.

The blue pigment is C. I. Pigment Blue 15:3 and 15:4. Among these, blue pigments are more resistant to fading and have a similar degree of fading, that is, weather resistance, to other inks; therefore, C.I. I. Pigment Blue 15:4. A blue pigment may be used in combination.

The content of blue pigment in the blue ink is not particularly limited. For example, the content of the blue pigment in the blue ink is preferably 1% by mass or more, more preferably 1.5% by mass or more. Further, the content of the blue pigment in the blue ink is preferably 15% by mass or less, and more preferably 10% by mass or less. When the content of the blue pigment is within the above range, the resulting ink set can easily express designs with a wider color gamut. Additionally, the selected blue pigment has similar weather resistance to other ink pigments. As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

Note that the binder resin, dispersant, solvent, and optional components contained in the blue ink are the same as those described above in connection with the yellow ink. Therefore, explanation regarding these components will be omitted. Further, the physical properties of the blue ink are similar to the physical properties of the ink described above in relation to the yellow ink.

(black ink)
Black ink is preferably included in the ink set of this embodiment. The black ink includes a pigment (black pigment), a binder resin, a dispersant, and a solvent.

The black pigment is not particularly limited. For example, black pigments include carbon pigments (C.I. Pigment Black 7), bismuth manganese pigments, yttrium manganese pigments, copper chromium pigments (C.I. Pigment Black 28), and copper iron manganese pigments. These include pigments (C.I. Pigment Black 26), cobalt iron chromium pigments (C.I. Pigment Black 27), ruthenium oxide, cobalt manganese pigments, titanium manganese pigments, and the like. A black pigment may be used in combination. Among these, it is preferable that the black pigment contains a carbon-based pigment because it is more resistant to fading and has a similar degree of fading, that is, a degree of weather resistance, to other inks. A black pigment may be used in combination.

When black ink is included, the content of black pigment in the black ink is not particularly limited. For example, the content of the black pigment in the black ink is preferably 1% by mass or more, more preferably 1.5% by mass or more. Further, the content of the black pigment in the black ink is preferably 15% by mass or less, more preferably 10% by mass or less. When the content of the black pigment is within the above range, the obtained ink set can easily express designs with a wider color gamut. Additionally, the black pigment selected has similar weather resistance to other ink pigments. As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

Note that the binder resin, dispersant, solvent, and optional components contained in the black ink are the same as those described above in connection with the yellow ink. Therefore, explanation regarding these components will be omitted. Further, the physical properties of the black ink are similar to the physical properties of the ink described above in relation to the yellow ink.

Returning to the description of the ink as a whole, the average particle diameter of the yellow pigment, red pigment, blue pigment, and preferably black pigment contained in each ink may be 120 nm or more, preferably 130 nm or more, More preferably, the thickness is 150 nm or more. Further, the average particle diameter may be 250 nm or less, preferably 245 nm or less, and more preferably 240 nm or less. When the average particle diameter is less than 120 nm, the obtained printed matter tends to have a poor degree of discoloration of the inkjet image layer, that is, poor weather resistance. On the other hand, if the average particle diameter exceeds 250 nm, the ink tends to clog a nozzle or the like when applied to a substrate by an inkjet method, and the ejection stability tends to decrease. Moreover, when the average particle diameter exceeds 250 nm, the ink tends to reduce the visibility of the design formed on the base material. Therefore, when the average particle diameter is within the above range, the obtained printed matter has excellent transparency of the inkjet image layer. Therefore, the design formed on the base material is less likely to be damaged. Further, the above-mentioned predetermined pigment is selected as the pigment of the ink. An ink set made of such inks can express designs with a wide color gamut. In addition, the selected pigments have similar weather resistance for each hue (yellow, red, blue (and black)). As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time. In addition, in this embodiment, the average particle diameter can be measured by a dynamic light scattering method using Zetasizer Nano series manufactured by Malvern Instruments.

The inks of this embodiment (yellow ink, blue ink, and red ink) are coated to have a film thickness of 20 μm, and the average light transmittance of the inkjet image layer (film thickness 20 μm) at a wavelength of 280 to 380 nm is 20% or less. It is preferably 15% or less, and more preferably 15% or less. Note that the lower limit of the average light transmittance of the ink is not particularly limited. In this embodiment, the average light transmittance is measured in the wavelength range of 300 to 2500 nm according to JIS R 3106 using an ultraviolet-visible near-infrared spectrophotometer (UV-3600plus, manufactured by Shimadzu Corporation). It can be calculated by measuring the light transmittance (%) every 1 nm. The ink included in the ink set of this embodiment has an inkjet image layer obtained within the above average light transmittance range, so that the transmittance of the inkjet image layer in the ultraviolet light region is kept low. As a result, the resulting prints have excellent weather resistance, with the pigments in the inkjet image layer being less likely to be damaged.

Further, among the inks included in the ink set of this embodiment, the yellow ink has an average light transmittance of 50% or more in the wavelength range of 530 to 580 nm of the inkjet image layer obtained by coating it to a film thickness of 20 μm. It is preferably 55% or more, and more preferably 55% or more. Further, the average light transmittance of the inkjet image layer obtained by coating the yellow ink to a film thickness of 20 μm at a wavelength of 530 to 580 nm is preferably 90% or less, more preferably 85% or less. . By containing the yellow ink in which the average light transmittance of the inkjet image layer made of the yellow ink at a wavelength of 530 to 580 nm is within the above range, the obtained printed matter easily transmits yellow visible light. As a result, the resulting print does not easily damage the design formed on the base material.

Among the inks included in the ink set of this embodiment, the red ink is coated to a film thickness of 20 μm, and the average light transmittance of the inkjet image layer obtained at a wavelength of 630 to 680 nm is 50% or more. It is preferably 55% or more, and more preferably 55% or more. Further, the average light transmittance of the inkjet image layer obtained by applying the red ink to a film thickness of 20 μm at a wavelength of 630 to 680 nm is preferably 90% or less, more preferably 85% or less. . By containing the red ink in which the average light transmittance of the inkjet image layer made of the red ink at a wavelength of 630 to 680 nm is within the above range, the obtained printed matter easily transmits red visible light. As a result, the resulting print does not easily damage the design formed on the base material.

Among the inks included in the ink set of this embodiment, the blue ink is coated to a film thickness of 20 μm, and the average light transmittance of the inkjet image layer obtained at a wavelength of 780 to 830 nm is 50% or more. It is preferably 55% or more, and more preferably 55% or more. Further, the average light transmittance of the inkjet image layer obtained by coating the blue ink to a film thickness of 20 μm at a wavelength of 780 to 830 nm is preferably 90% or less, more preferably 85% or less. . By containing the blue ink in which the average light transmittance of the inkjet image layer made of blue ink at a wavelength of 780 to 830 nm is within the above range, visible blue light is easily transmitted through the obtained print. As a result, the resulting print does not easily damage the design formed on the base material.

Among the inks included in the ink set of this embodiment, the yellow ink is such that the inkjet image layer obtained by coating it to a film thickness of 20 μm satisfies b*≧65 in the L*a*b* color system and is red. The ink is coated to a thickness of 20 μm, and the resulting inkjet image layer satisfies a*≧40 in the L*a*b* color system, and the blue ink is coated to a thickness of 20 μm. It is preferable that the inkjet image layer satisfies b*≦-35 in the L*a*b* color system. In such an ink set, the yellow ink, red ink, and blue ink all satisfy the above ranges, so that the resulting printed matter has excellent color development. In this embodiment, a* and b* in the L*a*b* color system can be measured using, for example, a spectrophotometer (manufactured by Konica Minolta, Inc., CM-3700). can.

It is preferable that the yellow ink is applied so that the resulting inkjet image layer satisfies b*≧65 in the L*a*b* color system, more preferably b*≧70.

It is preferable that the inkjet image layer obtained by applying the red ink to a film thickness of 20 μm satisfies a*≧40 in the L*a*b* color system, and more preferably satisfies a*≧45.

It is preferable that the inkjet image layer obtained by applying the blue ink to a film thickness of 20 μm satisfies b*≦-35 in the L*a*b* color system, and more preferably satisfies b*≦-40. preferable.

The ink set of this embodiment forms an ink image on the base material by discharging it onto the base material using an inkjet device that employs an inkjet method, and then hardens (dries) the ink to form a printed material. can be manufactured. Each ink constituting the ink set contains a specific pigment, and the average particle diameter of the pigment is 120 to 250 nm. As described above, the pigment used in the ink of this embodiment has a small average particle diameter, and the transparency of the inkjet image layer is excellent. Therefore, it is difficult to damage the design formed on the base material. Furthermore, a predetermined pigment is selected as the pigment for each ink. An ink set containing such ink can express designs with a wide color gamut. In addition, the selected pigments have similar weather resistance for each hue (yellow, red, blue). As a result, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is likely to be maintained over a long period of time.

<Manufacturing method of printed matter and printed matter>
A method for manufacturing a printed product according to an embodiment of the present invention includes a printing step of applying ink to a base material by an inkjet method using an inkjet ink set, and a drying step of drying the ink. The method for producing a printed product according to the present embodiment only needs to include these printing steps and drying steps, and other steps are not particularly limited. Each will be explained below.

-Printing process The printing process is a process of applying the above-described ink onto a base material by an inkjet method.

The method of applying the ink constituting the ink set to the base material by the inkjet method is not particularly limited. These methods include continuous methods such as charge modulation method, microdot method, charged jetting control method, ink mist method, and on/off methods such as piezo method, pulse jet method, bubble jet (registered trademark) method, and electrostatic suction method. An example is a demand method.

The substrate to which the ink is applied is not particularly limited. For example, the base material is a metal plate such as a steel plate, aluminum or stainless steel, a plastic plate or film such as acrylic, polycarbonate, ABS, polypropylene, polyester, or vinyl chloride, a ceramic plate, concrete, wood, glass, etc. These substrates may be treated with a pretreatment agent before printing. Examples of the pretreatment agent include fluorine-based paints, silicone-based paints, acrylic silicone-based paints, acrylic-based paints, epoxy-based paints, and urethane-based paints. Examples of methods for applying these pretreatment agents to the substrate include a spray method, a roll coater method, a curtain flow coater method, a brush coating method, a spatula coating method, a dipping method, and an inkjet method. Moreover, the base material of this embodiment may have various designs (for example, silver-based or pearl-based designs) expressed by applying paint to the surface. According to the method for manufacturing a printed product of this embodiment, the ink included in the above-described ink set is applied. The ink has a small average particle diameter of the pigment, and the transparency of the inkjet image layer is excellent. Therefore, even if a silver-based design or the like is formed on the base material, the design is unlikely to be damaged.

- Drying process The drying process is a process of drying the above-mentioned ink. Drying conditions are not particularly limited. For example, drying is performed by heat treatment at 50 to 250°C for 1 to 60 minutes. Such drying removes the solvent in the ink. Drying is preferably carried out at the same time or immediately after the ink is applied to the substrate in order to prevent bleeding of the inkjet image layer.

The resulting print includes a substrate and an inkjet image layer on which the inks forming the ink set are applied. The inkjet image layer includes yellow ink, red ink and blue ink. Note that the solvent of each ink has been removed by the above-described drying process. Therefore, the applied yellow ink, red ink, and blue ink each contain a pigment, a binder resin, and a dispersant. As mentioned above, the average particle size of the pigment is 120 to 250 nm. The pigment in the yellow ink is C.I. I. Pigment Yellow 138, 150, 151, 154 and 184. The pigment in the red ink is C.I. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. Contains at least one species selected from the group consisting of Pigment Violet 19. The pigment in the blue ink is C.I. I. Pigment Blue 15:3 and 15:4.

As described above, according to the method for manufacturing a printed product of the present embodiment, the obtained printed product is a printed product to which the ink included in the above-described ink set has been applied. Such prints can express designs with a wide color gamut. Further, in the resulting print, only a predetermined hue (for example, yellow or red) is prevented from fading, and the desired design is easily maintained over a long period of time.

Hereinafter, the present invention will be explained in more detail with reference to Examples. The present invention is not limited to these examples at all.

The raw materials used are shown below.
(pigment)
Yellow pigment 1: C. I. Pigment Yellow 138, Sicopal Yellow D1080J, manufactured by BASF Japan Ltd. Yellow pigment 2: C.I. I. Pigment Yellow 150, Chromophtal Yellow D1085J, BASF Japan Ltd. Yellow Pigment 3: C.I. I. Pigment Yellow 151, Ink Jet Yellow H4G, Clariant Japan Co., Ltd. Yellow Pigment 4: C.I. I. Pigment Yellow 154, Chromophtal Yellow L 1084 HD, manufactured by BASF Japan Ltd. Yellow pigment 5: C.I. I. Pigment Yellow 184, Sicopal Yellow L 1130, BASF Japan Co., Ltd. Yellow Pigment 6: C.I. I. Pigment Yellow 180, PVFast Yellow HG01 VP2657, Clariant Japan Co., Ltd. Yellow Pigment 7: C.I. I. Pigment Yellow 42, HY-100, manufactured by Titan Kogyo Co., Ltd. Red pigment 1: C.I. I. Pigment Red 122, Ink Jet Magenta E02, Clariant Japan Co., Ltd. Red Pigment 2: C.I. I. Pigment Red 179, Paliogen Red L3885, BASF Japan Ltd. Red Pigment 3: C.I. I. Pigment Red 202, Cinquasi Magenta L4540, BASF Japan Ltd. Red Pigment 4: C.I. I. Pigment Red 254, Iragazin Red L3630, BASF Japan Co., Ltd. Red Pigment 5: C.I. I. Pigment Red 264, Iragazin Red L4025, BASF Japan Ltd. Red Pigment 6: C.I. I. Pigment Violet 19, InkJet Magenta E5B 02, Clariant Japan Co., Ltd. Red Pigment 7: C.I. I. Pigment Red 112, Irgalite Red L3865HD, BASF Japan Ltd. Red Pigment 8: C.I. I. Pigment Red 101, R-516P, manufactured by Titan Kogyo Co., Ltd. Blue pigment 1: C.I. I. Pigment Blue 15:3, Hostaperm Blue B4G, Clariant Japan Co., Ltd. Blue Pigment 2: C.I. I. Pigment Blue 15:4, CHROMO FINE BLUE 6332 JC, Dainichiseika Chemical Co., Ltd. Blue Pigment 3: C.I. I. Pigment Blue 28, dipyroxide blue #9410, manufactured by Dainichiseika Kagyo Co., Ltd. Black pigment 1: C.I. I. Pigment Black 7, NIPEX35, Orion Engineered Carbons Co., Ltd. Black pigment 2: C.I. I. Pigment Black 28, NF-800 BLACK, manufactured by Nikken Co., Ltd. (resin)
Resin 1: Fluororesin, LF-200F, trifluoroethylene/vinyl monomer alternating copolymer, manufactured by Asahi Glass Co., Ltd., hydroxyl value: 50 mgKOH/g, acid value: 0 mgKOH/g, Mw: 20000, relative to diethylene glycol diethyl ether Solubility: 1000 (g/L) or more, Solubility in water: 6 (g/L), Nonvolatile content: 100%
(dispersant)
Dispersant 1: Basic polyester dispersant, Solsperse 33000, manufactured by Nippon Lubrizol Co., Ltd. (solvent)
Solvent 1: DEDG (diethylene glycol diethyl ether), glycol ether solvent, boiling point: 189°C, SP value: 8.6, manufactured by Nippon Nyukazai Co., Ltd. (other)
Curing agent: SBN-70D, blocked isocyanate, manufactured by Asahi Kasei Chemicals Co., Ltd. Curing catalyst: dibutyltin dilaurate UVA: Tinuvin479, manufactured by BASF Japan Co., Ltd. HALS: Tinuvin123, manufactured by BASF Japan Co., Ltd.

<Inkjet ink set>
Each ink was prepared according to the formulation (unit: parts by mass) shown in Table 1 below, and each color ink was combined with the formulation shown in Table 2 to ink each color of Examples 1 to 13 and Comparative Examples 1 to 6. An ink set consisting of Specifically, each component was mixed with a resin using a mixer and filtered to prepare ink of each color, and then combined to produce each ink set. Using the obtained ink set, DUFLOON 100 Silver (manufactured by Nippon Paint Co., Ltd.) was applied to a base material (electrodeposition coated steel plate) to a DRY film thickness of 25 μm using air spray under the following inkjet conditions. Inkjet printing was performed on the base material prepared by drying for 1 hour in a ℃ atmosphere to produce a printed product, and the design and weather resistance were evaluated. Regarding color development, visible light transmittance, and ultraviolet light transmittance, the substrate was corona-treated ETFE (thickness 250 μm, manufactured by AGC Co., Ltd.) and prints were produced under the same conditions. .

<Inkjet conditions>
Single pass method Dot size: 40pl
Nozzle diameter: 40μm
Drive voltage: 80V
Pulse width: 10μm
Frequency: 10kHz
Resolution: 400 x 800dpi
Coating amount: 20g/m ²
Base material temperature: 50℃ (warming)
Pattern: Solid pattern of each color ink <Drying conditions>
Heat drying (110℃ environment, 30 minutes)

When producing the above printed matter, the viscosity of each ink, the average particle diameter of the pigment, the light transmittance of the inkjet image layer (the ink's visible light transmittance, the ink's ultraviolet light transmittance), the design of the base material, was confirmed according to the evaluation criteria below. Furthermore, regarding the above prints, the coloring properties of the base material and the weather resistance of the inkjet image layer were measured. The results are shown in Table 1 or Table 2.

The method for measuring physical property values is shown below.
<Ink viscosity>
The prepared ink was adjusted to 30° C., and the viscosity (mPa·s) was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVB-20LT, rotor rotation speed 60 rpm).

<Average particle diameter of pigment>
The prepared ink was diluted 2500 times with cyclohexanone, and the average particle diameter (nm) was measured by dynamic light scattering using Zetasizer Nano S manufactured by Malvern Instruments.

<Visible light transmittance of inkjet image layer>
For each print (ink coating thickness: 20 μm), a UV-visible near-infrared spectrophotometer (UV-3600plus, manufactured by Shimadzu Corporation) was used to measure wavelengths from 300 to 2500 nm according to JIS R 3106. The light transmittance (%) of the area was measured every 1 nm. The inkjet image layer of the yellow ink part has an average light transmittance of 530 to 580 nm, the inkjet image layer of the red ink part has an average light transmittance of 630 to 680 nm, and the inkjet image layer of the blue ink part has an average light transmittance of 780 to 830 nm. The transmittance was confirmed.

<Ultraviolet light transmittance of inkjet image layer>
For each print (ink coating thickness: 20 μm), a UV-visible near-infrared spectrophotometer (UV-3600plus, manufactured by Shimadzu Corporation) was used to measure wavelengths from 300 to 2500 nm according to JIS R 3106. The light transmittance (%) of the area was measured every 1 nm. The average light transmittance of the inkjet image layer of each color ink in the wavelength range of 280 to 380 nm was confirmed.

<Design of base material>
The design quality of the base material for each print was visually confirmed.
○: The silver feel of the base material is felt △: The silver feel of the base material is slightly felt ×: The silver feel of the base material is not felt at all

<Color development>
Each print was measured using a spectrophotometer (CM-3700, manufactured by Konica Minolta, Inc.).
Good: Result 1 (yellow ink satisfies 65≦b*, red ink satisfies 40≦a*, and blue ink satisfies b*≦-35).
Δ: Out of yellow ink, red ink, and blue ink, one or two colors did not correspond to Result 1.
×: None of the colors corresponded to Result 1.

<Weather resistance of inkjet image layer>
Each print was irradiated with 750 MJ/m ² at an illuminance of 60 W/m ² as an accelerated weathering test using a xenon weather meter (Suga Test Instruments Co., Ltd., SUV-W161), and the print before irradiation was We measured the color difference of objects.
(Color difference measurement method)
The color difference was defined as the ΔE after the accelerated weathering test of the printed product compared to before the accelerated weathering test. The color difference was measured using a spectrophotometer (CM-3700, manufactured by Konica Minolta, Inc.).
(Evaluation criteria)
Good: The color difference of any color ink was also ΔE≦3.
Δ: The color difference of any color ink was 3<ΔE≦5.
×: The color difference of any color ink was ΔE>5.

As shown in Tables 1 and 2, all of the prints obtained in Examples 1 to 13 do not easily damage the design of the base material, exhibit excellent color development, and express designs with a wide color gamut. It was thought that it could be done. In addition, it was considered that in the printed products of Examples 1 to 13, only a predetermined hue of the resulting design was prevented from fading, and the desired design was likely to be maintained over a long period of time. On the other hand, among the various colored inks, the prints obtained in Comparative Examples 1 to 6, which did not employ the pigment combination of the present invention, had poor weather resistance, the design of the base material was impaired, and the color development was poor. "It is possible to express a design with a wide color gamut, the transparency of the inkjet image layer is excellent, it is difficult to damage the design formed on the base material, and it is possible to achieve a desired hue from the resulting design." The problem of "obtaining a printed product in which fading of color is prevented and a desired design is easily maintained over a long period of time" was not satisfied.

Claims (8)

The ink includes yellow ink, red ink and blue ink,
The yellow ink, the red ink, and the blue ink each include a pigment, a binder resin, a dispersant, and a solvent,
The average particle diameter of the pigment is 120 to 250 nm,
The pigment in the yellow ink is C.I. I. Pigment Yellow 138, 150, 151, 154 and 184,
The pigment in the red ink is C.I. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. containing at least one species selected from the group consisting of Pigment Violet 19,
The pigment in the blue ink is C.I. I. An inkjet ink set containing Pigment Blue 15: 3 . The yellow ink has an average light transmittance of 50 to 90% at a wavelength of 530 to 580 nm of an inkjet image layer obtained by coating to a film thickness of 20 μm,
The red ink has an average light transmittance of 50 to 90% at a wavelength of 630 to 680 nm of an inkjet image layer obtained by applying the red ink to a film thickness of 20 μm,
2. The inkjet ink set according to claim 1, wherein the blue ink is coated to a thickness of 20 μm, and the resulting inkjet image layer has an average light transmittance of 50% to 90% at a wavelength of 780 to 830 nm. 1. The yellow ink, the red ink, and the blue ink are each coated to a thickness of 20 μm, and the resulting inkjet image layer has an average light transmittance of 20% or less at a wavelength of 280 to 380 nm. or the inkjet ink set described in 2. The yellow ink is applied so that the inkjet image layer obtained by coating it to a film thickness of 20 μm satisfies b*≧65 in the L*a*b* color system,
The red ink is applied so that the inkjet image layer obtained by coating it to a film thickness of 20 μm satisfies a*≧40 in the L*a*b* color system,
The blue ink is applied to a film thickness of 20 μm, and an inkjet image layer obtained satisfies b*≦−35 in the L*a*b* color system, according to any one of claims 1 to 3. inkjet ink set. The inkjet ink set according to claim 1, wherein the binder resin is a fluororesin. 6. The inkjet ink set according to claim 5, wherein the fluororesin is a copolymer of fluoroethylene and vinyl monomer. A printing step of applying ink to a substrate by an inkjet method using the inkjet ink set according to any one of claims 1 to 6;
and a drying step of drying the ink. comprising a base material and an inkjet image layer on which ink constituting the ink set is applied,
The inkjet image layer includes yellow ink, red ink and blue ink,
The yellow ink, the red ink, and the blue ink each contain a pigment, a binder resin, and a dispersant,
The average particle diameter of the pigment is 120 to 250 nm,
The pigment in the yellow ink is C.I. I. Pigment Yellow 138, 150, 151, 154 and 184,
The pigment in the red ink is C.I. I. Pigment Red 122, 179, 202, 254, 264 and C.I. I. containing at least one species selected from the group consisting of Pigment Violet 19,
The pigment in the blue ink is C.I. I. Pigment Blue 15: Print containing 3 .