JP2015183064A - Ink composition for inkjet printing - Google Patents

Abstract

An ink composition for ink jet printing capable of forming a glossy printed matter while changing its hue according to a viewing angle is provided.
An ink composition for ink jet printing comprising a structural color pigment and a phosphoric acid group-containing polymer, wherein the mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is 0.2 to 2.0. It is a thing.
[Selection figure] None

Description

  The present invention relates to an ink composition for ink-jet printing, and more particularly to an ink composition for ink-jet printing capable of forming a glossy printed material while changing its hue according to the viewing angle.

  Conventionally, in the industrial fields of automobiles, building materials, etc. and various plastics used in household electrical appliances, etc., an ink composition containing a metal pigment or a pearl pigment is used as a plastic to express a design with excellent metallic luster and pearl luster. A method of applying on a substrate has been proposed.

  For example, Japanese Patent Laid-Open No. 2011-173943 (Patent Document 1) uses a pearlescent pigment including at least a thin plate-like substrate, an interference layer, an intermediate layer, a reflective layer, and a protective layer, and adjusts the refractive index of the pearlescent pigment. By doing so, it is described that the brightness of the interference light can be increased and a strong pearl luster can be obtained.

JP 2011-173943 A

  However, the pearlescent pigment as described in Patent Document 1 has a multilayer structure in which a thin plate-like base material is coated with a metal compound and a resin, and it has a visual effect due to a hue difference between highlight and shade. Although pearly luster is expressed, if the color of reflected light is low, the luster is insufficient and sufficient pearly luster may not be obtained. Further, as a means for enhancing the visual effect, a technique of increasing the particle diameter of a metal pigment or a pearl pigment is known, but there is a problem that nozzles are clogged during ink jet printing.

  By the way, among the pigments called metal pigments and pearl pigments, those classified as structural color pigments are known. The structural color pigment has a regular concavo-convex shape on its surface, and the concavo-convex shape interferes with light like a diffraction grating, so it can express a structural color whose hue changes according to the viewing angle. it can.

  In order to express the structural color, a method of blending the structural color pigment into the ink composition for inkjet printing can be considered, but when printed using an inkjet printer, the structural color pigment in the printed material has poor orientation and gloss. There is a problem that the interference cannot be obtained sufficiently and the coherence becomes weak.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink composition for ink jet printing capable of solving the above-mentioned problems of the prior art and forming a glossy printed matter while changing the hue according to the viewing angle.

  As a result of intensive studies to achieve the above object, the present inventor has found that the structural color pigment has a complicated structure on the surface, so that the specific surface area is increased and the cohesive force is increased. It has been found that the dispersibility of the structural color pigment in the composition is low, the orientation of the structural color pigment in the printed matter is also deteriorated, and there are problems in gloss and interference. And when the present inventor further examined, by blending the phosphate group-containing polymer in a specific ratio with the ink composition for inkjet printing containing the structural color pigment, the hue changes according to the viewing angle. The inventors have found that a glossy printed material can be formed, and have completed the present invention.

  That is, the ink composition for inkjet printing of the present invention includes a structural color pigment and a phosphate group-containing polymer, and the mass ratio of the structural color pigment to the phosphate group-containing polymer is 0.2 to 2.0. It is characterized by.

  In the suitable example of the ink composition for inkjet printing of this invention, content of the said phosphate group containing polymer is 0.1-2.0 mass%.

  In another preferred embodiment of the ink composition for ink jet printing of the present invention, it further comprises a polyester resin having a weight average molecular weight of 12,000 or less.

  In another preferred embodiment of the ink composition for ink jet printing according to the present invention, the structural color pigment is obtained by natural filtration using a twilled woven wire mesh as a filter.

  According to the present invention, an ink composition for ink jet printing capable of forming a glossy printed matter while changing its hue according to the viewing angle by combining the structural color pigment and the phosphate group-containing polymer in a specific ratio. Can be provided.

  The ink composition for ink jet printing of the present invention (hereinafter also simply referred to as the ink composition of the present invention) will be described in detail below. The ink composition for inkjet printing of the present invention comprises a structural color pigment and a phosphate group-containing polymer, and the mass ratio of the structural color pigment to the phosphate group-containing polymer is 0.2 to 2.0. And

  The structural color pigment used in the ink composition of the present invention is a metal pigment having a thin and flat shape such as a foil, and its surface has a regular uneven shape to interfere with light like a diffraction grating. Is formed. In addition, the shape of a convex part is not specifically limited, A line, a square, a circle | round | yen, etc. are mentioned. Although the space | interval of a convex part and a convex part is not specifically limited, For example, it is the range of 0.1-1.0 micrometer.

  As the structural color pigment, a pigment having metallic luster is used, and specifically, aluminum, silver, gold, nickel, chromium, tin, zinc, copper and the like can be mentioned. In addition, a structural color pigment may be used individually by 1 type, and may be used in combination of 2 or more type.

The structural color pigment preferably has a volume-based particle size distribution with a 90% particle diameter (D ₉₀ ) of 2.0 to 20.0 μm. When the 90% particle diameter (D ₉₀ ) of the structural color pigment exceeds 20.0 μm, nozzle clogging may occur during ink jet printing. The 90% particle diameter (D ₉₀ ) can be determined from the particle size distribution measured using a normal particle size distribution measuring device (for example, a laser diffraction / scattering particle size distribution measuring device).

  Furthermore, it is preferable to use the structural color pigment obtained by natural filtration using a twilled woven wire mesh as a filter. By performing natural filtration using a twilled woven wire mesh, the structural color pigment can be prevented from aggregating in the ink composition, and nozzle clogging during ink jet printing can also be prevented. The twilled woven wire mesh is preferably made of stainless steel or iron having a wire diameter of 0.02 to 0.07 mm from the viewpoint of making the particle diameter of the structural color pigment finer, specifically, JIS standard. A # 3600 to # 2300 mesh twilled woven wire mesh according to (JIS Z8801) is particularly preferred.

  The structural color pigment is commercially available, for example, in the form of a dispersion, and a commercially available product can be suitably used.

  In the ink composition of the present invention, the content of the structural color pigment is preferably 0.3 to 1.5% by mass. If the content of the structural color pigment is less than 0.3% by mass, sufficient interference may not be obtained. On the other hand, if it exceeds 1.5% by mass, the gloss may be lowered.

  Since the phosphoric acid group-containing polymer used in the ink composition of the present invention can improve the dispersion stability of the structural color pigment, the orientation of the structural color pigment in the printed matter is improved, and the hue depends on the viewing angle. It becomes possible to form a glossy printed matter as the temperature changes.

  In the ink composition of the present invention, in order to improve the dispersion stability of the structural color pigment, it is also important to define the ratio of the phosphate group-containing polymer and the structural color pigment. The mass ratio of the structural color pigment to the coalescence is required to be 0.2 to 2.0. If the mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is less than 0.2, the amount of the phosphoric acid group-containing polymer is too small relative to the specific surface area of the structural color pigment, so that the structural color pigment tends to aggregate. On the other hand, if it exceeds 2.0, the amount of the phosphoric acid group-containing polymer is too large relative to the specific surface area of the structural color pigment, so that the phosphoric acid group-containing polymer may float on the ink film surface. .

  The phosphate group-containing polymer is a polymer having a phosphate group, a phosphate group, or a phosphate ester group. Note that the phosphate ester group has a structure in which part or all of the hydrogen of the phosphate group is substituted with an organic group such as an alkyl group. Examples of the phosphate group include alkali metal salts, alkaline earth metal salts, amine salts, ammonium salts and the like. The main chain constituting the phosphate group-containing polymer is preferably selected from the group consisting of a vinyl monomer polymer or copolymer, polyether, polyester, and copolymers thereof. In addition, a phosphate group containing polymer may be used individually by 1 type, and may be used in combination of 2 or more type.

  The phosphate group-containing polymer is not particularly limited. For example, (i) a vinyl monomer having a phosphate group, a phosphate group or a phosphate ester group is copolymerized with another vinyl monomer. Or (ii) by polymerizing a polymer having one or more hydroxyl groups and a compound having a phosphate group, a phosphate group or a phosphate ester group.

  Examples of vinyl monomers having a phosphate group, a phosphate group or a phosphate ester group include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acryloyl phosphate and phenyl-2-acryloyloxyethyl phosphate. Examples include phosphoric acid monoesters.

  Other vinyl monomers include aromatic vinyl hydrocarbons such as styrene, α-methyl styrene, vinyl toluene, 2,4-dimethyl styrene, ethyl styrene, phenyl styrene, cyclohexyl styrene, and benzyl styrene; hydroxystyrene, Hydroxy group-containing vinyl monomers such as N-methylol (meth) acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, 2-hydroxyethylpropenyl ether, sucrose allyl ether, methyl (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) Acrylate, hexadecyl (meth) acrylate, eicosyl (meth) alkyl acrylate such as (meth) acrylate.

  On the other hand, examples of the polymer having one or more hydroxyl groups include polymers or copolymers of vinyl monomers, polyethers, polyesters (including polycaprolactone), and the like.

  A polymer or copolymer of vinyl monomers can be synthesized by using, for example, the above-described vinyl monomers.

  Examples of the polyether include polyalkylene ether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol.

  Examples of polyesters include polycondensates of polyols with polycarboxylic acids, acid anhydrides or lower alkyl esters thereof, polyaddition products of γ-butyrolactone, polyaddition products of ε-caprolactone, and the like. Here, examples of the polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, octanediol, decanediol, dodecanediol, and tetradecane. Examples include alkylene glycols such as diols; alkylene ether glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Examples of polycarboxylic acids include succinic acid, adipic acid, sebacic acid, dodecenyl succinic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and alkylenedicarboxylic acid such as octadecanedicarboxylic acid; alkenylene dicarboxylic acid such as maleic acid and fumaric acid, etc. Is mentioned.

  Examples of the compound having a phosphate group, a phosphate group or a phosphate ester group include (mono, di, tri) alkyl esters having 1 to 12 carbon atoms of phosphoric acid in addition to phosphoric acid and phosphate. It is done.

The phosphate group-containing polymer preferably has a weight average molecular weight of 1,000 to 12,000. In the present invention, the weight average molecular weight is a value measured by gel filtration chromatography, and polystyrene is used as a standard substance.
Moreover, it is preferable that the mg number of potassium hydroxide required in order to neutralize 1 g of this phosphate group containing polymer is 100-150 mgKOH / g in the said phosphate group containing polymer. Such a value can be measured by a neutralization titration method.

  In addition, the phosphoric acid group containing polymer is marketed, for example as a dispersing agent, and commercial items, such as DISPERBYK-111 (the dispersing agent made by a Big Chemie), can be used conveniently.

  In the ink composition of the present invention, the content of the phosphate group-containing polymer is preferably 0.1 to 2.0% by mass. When the content of the phosphoric acid group-containing polymer exceeds 2.0% by mass, an excessive amount of the phosphoric acid group-containing polymer floats on the surface of the ink film, so that the metallic gloss may be lowered.

  The ink composition of the present invention preferably further contains a polyester resin having a weight average molecular weight of 12,000 or less as a binder resin from the viewpoint of forming a structural color printed matter having excellent abrasion resistance in addition to metallic luster. The polyester resin requires a weight average molecular weight of 12,000 or less, and preferably has a weight average molecular weight of 6,000 or less. If the weight average molecular weight of the polyester resin is 12,000 or less, the structural color pigment is not aggregated in the ink composition of the present invention, nozzle clogging at the time of inkjet printing can be prevented, and the metallic gloss is high. A structural color print can be obtained. On the other hand, when the weight average molecular weight of the polyester resin exceeds 12,000, the structural color pigment is poorly wetted, and the structural color pigment tends to aggregate in the ink drying process, which may reduce the interference. In addition, since a polyester resin comprises the resin base material of printed matter, it is preferable that the weight average molecular weight is 3,000 or more. In the present invention, the weight average molecular weight is a value measured by gel filtration chromatography, and polystyrene is used as the standard substance.

  The polyester resin preferably has an acid value of 5-50. If the acid value of the polyester resin is in the range of 5 to 50, the acid groups in the polyester resin react with the surface of the structural color pigment, and the structural color pigment can be further fixed to further improve the scratch resistance. In addition, wetting with the structural color pigment becomes better. If the acid value of the polyester resin exceeds 50, film properties such as weather resistance may be deteriorated.

  The polyester resin is a copolymer obtained by dehydrating polycondensation of a polyvalent carboxylic acid and a polyalcohol, which are monomers, by an ordinary method, and by adjusting the type and amount of the monomer used The desired weight average molecular weight is obtained.

  The polyvalent carboxylic acid is a carboxylic acid having two or more carboxyl groups. Specific examples thereof include fumaric acid, maleic acid, itaconic acid, orthophthalic acid, isophthalic acid, terephthalic acid, succinic acid, malonic acid, succinic acid, and glutar. Acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, tetradecanedicarboxylic acid, hexadecanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like can be mentioned. These polyvalent carboxylic acids may be used alone or in combination of two or more.

  Polyalcohol is an alcohol having two or more hydroxyl groups (—OH groups). Specific examples include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, and dipropylene glycol. , Tripropylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, butylethylpropanediol, 1 , 6-hexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexane Nji methanol, 1,4-cyclohexane diethanol, 1,10-decamethylene glycol, 1,12-dodecanediol, polyethylene glycol, polytrimethylene glycol, polytetramethylene glycol, and the like. These polyalcohols may be used alone or in combination of two or more.

  In the ink composition of the present invention, even if the polyester resin is blended in a high content of, for example, 3.0% by mass or more, the structural color pigment is not aggregated in the ink composition of the present invention, and the inkjet Although it is possible to prevent nozzle clogging during printing, the content of the polyester resin is preferably 10.0% by mass or less from the viewpoint of forming a glossy structural color print. On the other hand, in the ink composition of the present invention, the content of the polyester resin is preferably 3.0% by mass or more, and more preferably 5.0% by mass or more from the viewpoint of improving the scratch resistance of the printed matter.

  The ink composition of the present invention can contain an organic solvent as a solvent, but from the viewpoint of further improving the dispersion stability of the structural color pigment, for example, glycol ether is preferable. For example, ethylene glycol diethyl ether, propylene glycol diethyl Ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, Tetraethyleneglycol Dimethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, propylene glycol-n- Examples include propyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, and tripropylene glycol monomethyl ether. In addition, these organic solvents may be used individually by 1 type, and may be used in combination of 2 or more type. In the ink composition of the present invention, the content of the organic solvent is, for example, 84.0 to 95.0% by mass.

  The ink composition of the present invention can also be used as an active energy ray-curable ink, and an active energy ray-curable compound (for example, a monomer, an oligomer, or a polymer) commonly used in the ink industry, alone or in two kinds. The above can be mixed and used. The active energy ray-curable compound is not particularly limited as long as it is a compound that reacts or polymerizes upon irradiation with active energy rays such as ultraviolet rays and visible rays. Specifically, the active energy ray-curable compound is reactive when irradiated with active energy rays. Monofunctional compounds (monofunctional monomers, monofunctional oligomers, and monofunctional polymers) having one functional group exhibiting a polyfunctional compound having a plurality of functional groups that exhibit reactivity when irradiated with active energy rays (multifunctional compounds) Functional monomers, polyfunctional oligomers and polyfunctional polymers). Examples of the functional group that is reactive to active energy rays include an acrylate group, a methacrylate group, and a vinyl group.

  Specific examples of the active energy ray-curable compound include stearyl acrylate, tridecyl acrylate, lauryl acrylate, decyl acrylate, isodecyl acrylate, isobornyl acrylate, N-vinylcaprolactam, ethylene oxide (EO) modified 2-ethylhexyl acrylate, N- Vinyl-2-pyrrolidone, N-vinylimidazole, tetrahydrofurfuryl acrylate, 2-phenoxyethyl acrylate, methoxydipropylene glycol acrylate, ethoxydiethylene glycol acrylate, 3-ethyl-3-oxetanylmethyl acrylate, (2-methyl-2-ethyl -1,3-dioxolan-4-yl) methyl acrylate, (2-methyl-isobutyl-1,3-dioxolan-4-yl) methyl Monofunctional compounds such as acrylate, (5-ethyl-1,3-dioxane-5-yl) methyl acrylate, and 2- (2-vinyloxyethoxy) ethyl acrylate, and triethylene glycol diacrylate, 1,4- Butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylol Propane triacrylate, EO-modified trimethylolpropane triacrylate, propylene oxide (PO) -modified trimethylolpropane triacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate acrylate, EO-modified pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, polyfunctional compounds such as dipentaerythritol hexaacrylate. In addition, these active energy ray hardening compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

Moreover, in order to raise the intensity | strength of printed matter, it is preferable to use an acrylate oligomer, an acrylate polymer, etc. as an active energy ray hardening compound. Note that the acrylate oligomers and polymers, oligomers and polymers having acryloyloxy groups (CH ₂ = CHCOO-) one or more. As specific examples of acrylate oligomers and polymers, aminoacrylate oligomers and polymers [acrylate oligomers and polymers having a plurality of amino groups (—NH ₂ )], urethane acrylate oligomers and polymers [having a plurality of urethane bonds (—NHCOO—) Acrylate oligomer and polymer], epoxy acrylate oligomer and polymer [acrylate oligomer and polymer having a plurality of epoxy groups], silicone acrylate oligomer and polymer [acrylate oligomer and polymer having a plurality of siloxane bonds (-SiO-)], ester acrylate oligomer and polymer [Acrylate oligomers and polymers having a plurality of ester bonds (—COO—)] and butadiene acrylate Mer and polymers [acrylate oligomers and polymers having a plurality of butadiene unit], and the like. Moreover, as a commercial item, for example, beam set 502H, beam set 505A-6, beam set 505B, beam set 575, beam set AQ17 (made by Arakawa Chemical Industries), UA-306H, UA-306I, UA510H, UF- 8001G (manufactured by Kyoeisha Chemical), CN929, CN940, CN944B85, CN959, CN963E75, CN963E80, CN963J75, CN964, CN964A85, CN964E75, CN965, CN965A80, CN966A80, CN966A80, CN966B C981A75, CN981B88, CN982A75, CN982B88, CN982E75, CN 82P90, CN983, CN985B88, CN989, CN991, CN996, CN9001, CN9002, CN9004, CN9005, CN9006, CN9007, CN9008, CN9009, CN9010, CN9011, CN9014, CN9178, 983C -6HA, U-6LPA, UA-1100H, UA-53H, UA-33H, U-200PA, UA-4200, UA-122P (manufactured by Shin-Nakamura Chemical Co., Ltd.), New Frontier R-1214, New Frontier R-1301 , New Frontier R1304, New Frontier R-1306X, New Frontier R-1150D (Daiichi Kogyo Seiyaku Co., Ltd.), EBECRYL230, EBECRYL 44, EBECRYL245, EBECRYL264, EBECRYL265, EBECRYL270, EBECRYL284, EBECRYL285, EBECRYL294, EBECRYL1290, EBECRYL4820, EBECRYL5129, EBECRYL5129, EBECRYL5129 -7000B, UV-7461TE, UV-3000B, UV-3310B, UV-3520TL, UV-3700B (manufactured by Nippon Synthetic Chemical Co., Ltd.), Art Resin UN-333, UN-1255, UN-2600, UN-2700, UN- 5500, UN-5507, UN-6060P, UN-6200, UN-6300 , UN-6301, UN-7600, UN-7700, UN-900PEP, UN-9200A, UN-3320HA, UN-3320HC, UN-904 (manufactured by Negami Kogyo Co., Ltd.). In addition, these active energy ray hardening compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the ink composition of the present invention, the content of the active energy ray-curable compound is, for example, 84.0 to 95.0% by mass.

  When the ink composition of the present invention contains an active energy ray-curable compound, the ink composition preferably contains a photopolymerization initiator having an action of initiating polymerization of the active energy ray-curable compound. Furthermore, in order to accelerate the initiation reaction of the photopolymerization initiator, an auxiliary such as a photosensitizer can be used in combination.

  Examples of the photopolymerization initiator include benzophenone compounds, acetophenone compounds, thioxanthone compounds, phosphine oxide compounds, etc. From the viewpoint of curability, the wavelength of the active energy ray to be irradiated and the photopolymerization initiator It is preferable that the absorption wavelengths overlap as much as possible.

  Specific examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-hydroxy-2-methyl-1-phenylpropane. -1-one, benzophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-propan-1-one, 2-hydroxy-1- {4 -[4- (2-hydroxy-2-methylpropionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, phenylglyoxylic acid methyl ester, 2-methyl-1- [4- (methylthio ) Phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, 2 Dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, bis (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide , 1- [4- (phenylthio) phenyl] -1,2-octanedione, 2- (O-benzoyloxime) 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ]-, 1- (O-acetyloxime), 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, etc. Among them, 2,4,6-trimethylbenzoyl-diphenyl-phosphinone. Oxides are preferred from the viewpoint of curability, and these photopolymerization initiators may be used alone or in combination of two or more. It may be used together.

  In the ink composition of the present invention, the content of the photopolymerization initiator is, for example, 0.1 to 1.5% by mass.

  In the ink composition of the present invention, additives commonly used in the ink industry, for example, pigments other than structural color pigments, surface conditioners, wetting agents, thickeners, anti-settling agents, etc., impair the purpose of the present invention. It may be appropriately selected and blended within the range not to be used. Commercially available products can be suitably used for these additives.

  The ink composition of the present invention is a mixture of the structural color pigment and the phosphoric acid group-containing polymer, and various components appropriately selected as necessary. It can be prepared by filtering the resulting mixture using a filter having a pore size of about 1/10 or less.

  The ink composition of the present invention can be printed on various base materials such as plate materials, sheets, and papers such as coated paper. Here, examples of the base material include ABS resin, polycarbonate, polyvinyl chloride, acrylic resin, PP, PET and other plastics, metals such as iron, stainless steel, and aluminum, wood, glass, and ceramics. It is done.

  The ink composition of the present invention is an ink composition for inkjet printing and can be used in various inkjet printers. Examples of the ink jet printer include an ink jet printer that ejects an ink composition by a charge control method or an ink on demand method.

  Moreover, the printed matter formed on the base material by printing using an inkjet printer may be dried by heat and cured. In addition, when the ink composition of the present invention contains an active energy ray-curable compound, the active energy ray such as ultraviolet light is irradiated using a metal halide lamp, a high-pressure mercury lamp, or an ultraviolet LED after printing with an ink jet printer. It is preferable to cure the printed matter. The wavelength of the active energy ray irradiated for curing the printed material preferably overlaps with the absorption wavelength of the photopolymerization initiator, and the main wavelength of the active energy ray is preferably 360 to 425 nm.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Ink compositions of Examples 1 to 4, Comparative Examples 1 to 4, and Reference Example were prepared according to the formulation shown below. Specifically, in Examples 1, 3, 4, Comparative Examples 1 to 4 and Reference Examples, an organic solvent and an additive selected as necessary are stirred to obtain an ink solvent, and a polyester resin is added thereto. Thereafter, a structural color pigment was added, and the mixture was heated and stirred at 60 ° C. for 60 minutes to prepare an ink composition. In Example 2, an active energy ray-curable compound and an additive selected as necessary are stirred to obtain an ink solvent, and a structural color pigment is added thereto and stirred for 60 minutes to prepare an ink composition. did. In addition, about the synthesis | combination of a polyester resin, 320 parts by mass of isophthalic acid, 5 parts by mass of maleic anhydride, 200 parts by mass of neopentyl glycol were placed in a flask equipped with a thermometer, a stirrer, an N ₂ introduction tank and an outflow pipe with a partial condenser. And a dehydration condensation reaction at 240 ° C. until a predetermined acid value is obtained, whereby a polyester resin having a target molecular weight is obtained. The structural color pigment is obtained by natural filtration using a filter described in the formulation. And the vapor deposition aluminum pigment (without unevenness | corrugation) used by the comparative example 1 is obtained by carrying out the natural filtration of the aluminum pigment obtained by the manufacturing method using vapor deposition using the filter as described in a prescription.

<Example 1>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0% by mass, filter: “Taya Tatami weave # 2300 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKART)): 10.0 parts by mass, diethylene glycol ethyl methyl ether (organic solvent): 88.40 parts by mass, DISPERBYK- 111 (Bic Chemie's dispersant, phosphate group-containing polymer, nonvolatile content 95% by mass): 0.60 parts by mass / polyester resin (acid value 11, polystyrene-converted weight average molecular weight 6,000): 1.00 parts by mass The mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is 1.2.

<Example 2>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0 mass%, filter: “Taya Tatami mat # 2000 mesh”, “METALURE Primatic M 50720 BG” manufactured by ECKART): 10.0 mass parts, 1,6-hexanediol diacrylate (monomer): 66.40 mass Parts / triethylene glycol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.): 10.00 parts by mass Parts / LUCIRIN TPO (acylphosphine oxide photopolymerization initiator manufactured by BASF): 13.00 parts by mass The mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is 1.2.

<Example 3>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0 mass%, filter: “Taya Tatami weave # 2000 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKART): 10.0 parts by mass, diethylene glycol ethyl methyl ether (organic solvent): 89.40 parts by mass, DISPERBYK- 111 (Bic Chemie's dispersant, phosphate group-containing polymer, non-volatile content 95% by mass): 0.60 part by mass The mass ratio of the structural color pigment to the phosphate group-containing polymer is 1.2.

<Example 4>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0% by mass, filter: “Taya Tatami weave # 2000 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKALT): 10.0 parts by mass, diethylene glycol ethyl methyl ether (organic solvent): 88.40 parts by mass, DISPERBYK- 111 (Bic Chemie's dispersant, phosphate group-containing polymer, non-volatile content 95% by mass): 0.60 parts by mass / polyester resin (acid value 3, polystyrene equivalent weight average molecular weight 23,000): 1.00 parts by mass The mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is 1.2.

<Comparative Example 1>
Metallic pigment dispersion (deposited aluminum pigment (no irregularities): 10.0% by mass, 90% particle size (D ₉₀ ): 3.0 μm, solvent type: diethylene glycol ethyl methyl ether, filter: “Taya Tatami # 2000 Mesh "): 10.0 parts by mass-diethylene glycol ethyl methyl ether (organic solvent): 88.40 parts by mass-DISPERBYK-111 (BIC Chemie's dispersant, phosphate group-containing polymer, non-volatile content 95% by mass): 0 .60 parts by mass / polyester resin (acid value 11, polystyrene-converted weight average molecular weight 6,000): 1.00 parts by mass The mass ratio of the vapor-deposited aluminum pigment to the phosphate group-containing polymer is 1.8.

<Comparative Example 2>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0% by mass, filter: “Taya Tatami weave # 2000 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKART) 10.0 parts by mass, diethylene glycol ethyl methyl ether (organic solvent): 88.40 parts by mass, polyester resin ( Acid value 11, polystyrene conversion weight average molecular weight 6,000): 1.00 parts by mass

<Comparative Example 3>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0 mass%, filter: “Taya Tatami weave # 2000 mesh”, “METALURE Primatic M 50720 BG” manufactured by ECKART) 10.0 mass parts, diethylene glycol ethyl methyl ether (organic solvent): 84.00 mass parts, DISPERBYK-111 (Bic Chemie's dispersant, phosphate group-containing polymer, non-volatile content 95% by mass): 5.00 parts by mass. Polyester resin (acid value 11, polystyrene-converted weight average molecular weight 6,000): 1.00 parts by mass The mass ratio of the structural color pigment to the phosphate group-containing polymer is 0.1.

<Comparative Example 4>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 20 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0 mass%, filter: “Taya Tatami weave # 2000 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKART) 10.0 mass parts, diethylene glycol ethyl methyl ether (organic solvent): 88.05 mass parts, DISPERBYK-164 (Bic Chemie's dispersant, tertiary amine-containing polyester-modified urethane polymer, nonvolatile content 60% by mass): 0.95 parts by mass / polyester resin (acid value 11, polystyrene-converted weight average molecular weight 6,000): 1.00 parts by mass In addition, tertiary amine-containing polyester-modified urethane polymer weight The mass ratio of the structural color pigment to the body is 1.2.

<Reference example>
Structural color pigment dispersion (deposited aluminum, 90% particle size (D ₉₀ ): 25 μm or less, pigment content: 7.0% by mass, solvent type: 2-butoxyethanol 88.0% by mass and acetone 5. 0% by mass, filter: “Taya tatami mat # 1400 mesh”, “METALURE Primitive M 50720 BG” manufactured by ECKART)): 10.0 parts by mass, diethylene glycol ethyl methyl ether (organic solvent): 88.40 parts by mass, DISPERBYK- 111 (Bic Chemie's dispersant, phosphate group-containing polymer, non-volatile content 95% by mass): 0.60 parts by mass / polyester resin (acid value 3, polystyrene equivalent weight average molecular weight 6,000): 1.00 parts by mass The mass ratio of the structural color pigment to the phosphoric acid group-containing polymer is 1.2.

  Next, the ink composition is printed on a polyvinyl chloride base material (PVC100MP manufactured by Lintec Corporation) with a large format inkjet printer (head nozzle diameter: 30 μm, filter in head # 2300 mesh), and interference of the obtained printed matter And scratch resistance were evaluated by the following methods. The results are shown in Table 1. In the reference example, nozzle clogging occurred and printing could not be performed.

<Interference>
The printed matter was visually confirmed under sunlight, and the coherence was evaluated according to the following criteria.
◎ There is a metallic luster and the hue changes according to the viewing angle. ○ There is a metallic luster and the hue changes according to the viewing angle, but the interference is weak (partially interferes).
△ The hue changes depending on the viewing angle, but there is no metallic luster (interference due to some wavelengths).
× No interference

<Abrasion resistance>
Under the conditions of a load of 250 g, a width of 5 cm, and 10 reciprocations, the printed matter printed on the polyvinyl chloride base material was rubbed with a cotton swab, the printed matter was visually confirmed, and scratch resistance was evaluated according to the following evaluation criteria.
◎ There is no change in the printed matter ○ There is a slight change in the gloss of the printed matter △ There is a change in the gloss of the printed matter, and the substrate (polyvinyl chloride substrate) is slightly exposed × The printed material is scraped with a cotton swab and the substrate (poly (Vinyl chloride substrate) is exposed

  From Table 1, the ink compositions of Examples 1 and 2 have a glossy printed matter that changes in hue according to the viewing angle by combining the structural color pigment and the phosphate group-containing polymer at a mass ratio of 1.2. Furthermore, in Example 1, by using a polyester resin having a weight average molecular weight of 12,000 or less, the printed matter is excellent in scratch resistance. In Example 2, an active energy ray-curable compound is used, and the printed matter is excellent in scratch resistance. Although the ink composition of Example 3 is excellent in interference, it does not use a polyester resin and an active energy ray-curable compound, and therefore has poor scratch resistance. Since the ink composition of Example 4 includes a polyester resin having a weight average molecular weight of more than 12,000, a reduction in interference can be confirmed as compared with the ink compositions of Examples 1 to 3. It can be seen that if the weight average molecular weight of the polyester resin is too high, the coherence decreases. On the other hand, since the ink composition of Comparative Example 1 does not use a structural color pigment, there is no interference. Since the ink composition of Comparative Example 2 does not use a phosphate group-containing polymer, the interference property is low. In Comparative Example 4, a dispersant other than the phosphate group-containing polymer is used, but the interference is low.

Claims (4)

  An ink composition for inkjet printing, comprising a structural color pigment and a phosphate group-containing polymer, wherein the mass ratio of the structural color pigment to the phosphate group-containing polymer is 0.2 to 2.0.   The ink composition for ink jet printing according to claim 1, wherein the content of the phosphoric acid group-containing polymer is 0.1 to 2.0 mass%.   The ink composition for ink jet printing according to claim 1, further comprising a polyester resin having a weight average molecular weight of 12,000 or less.   The ink composition for inkjet printing according to any one of claims 1 to 3, wherein the structural color pigment is obtained by natural filtration using a twilled woven wire mesh as a filter.