JP2012092210A - Aqueous ultraviolet curing mold ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ultraviolet curing mold ink composition which can form an image, solid black image, half tone dot, etc. with a very thick film which has very strong ink coating and excellent abrasion resistance without a special drying apparatus.SOLUTION: The aqueous ultraviolet curing mold ink composition includes at least a glittering pigment, photopolymerizable compound, photopolymerization initiator and water, wherein the photopolymerization compound has at least one type of photopolymerization oligomer of five or more functionalities, and at least one type of urethane photopolymerization oligomer of two functionalities.

Description

  The present invention relates to a water-based ultraviolet curable ink composition that forms a high-thickness ink film containing a bright pigment, and in particular, does not require heat drying, and the leafing effect (orientation) of the bright pigment in the ink film. The aqueous ultraviolet curable ink composition is excellent in ink film strength and friction resistance.

  Water-based UV curable inks are generally made by adding water to UV curable varnishes for the purpose of reducing the viscosity of the inks, and those using water-soluble UV curable resins and surfactants. Some have been emulsified.

  For example, as an example using a water-soluble ultraviolet curable resin, there is a printing ink characterized by containing a water-soluble ultraviolet curable resin, water, and a water-soluble solvent (see, for example, Patent Document 1).

  For example, as an example of emulsification using a surfactant, an ultraviolet curable stencil in which an aqueous phase is finely dispersed in an oil phase comprising an ultraviolet curable ink and a nonionic surfactant having an HLB of 10 or less. There is a printing emulsion ink (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 4-117469 JP-A-8-3501

  However, the technique described in Patent Document 1 is intended to perform printing with a relatively low film thickness as a printing ink for corrugated cardboard, and is an ink film formed by penetrating ink into paper. When a thick ink film is formed, there is a problem that the friction resistance of the ink film may be lowered.

  The technique described in Patent Document 2 improves the temperature dependence of ink viscosity by emulsifying using a specific surfactant, and the water contained in the ink is from 20% by weight. Since it has a high composition of 85% by weight, it is necessary to evaporate the moisture with hot air before curing the ink with ultraviolet rays when printing an image with a high film thickness. Therefore, there is a problem that the equipment becomes large and the friction resistance of the ink film may be lowered.

  In addition, since the techniques described in Patent Documents 1 and 2 are not inventions aimed at forming a high-thickness ink film containing a glitter pigment, water is added to obtain the leafing effect of the glitter pigment. The water-based ultraviolet curable type has no need for thermal drying, which is the object of the present invention, has a leafing effect of the glitter pigment in the ink film, and has excellent ink film strength and friction resistance. The ink composition cannot be obtained.

  The present invention aims to solve the above-mentioned problems, and without forming a special drying device, the film strength is high even when a high-thickness ink film containing a bright pigment is formed, and the friction resistance is high. The present invention relates to an aqueous ultraviolet curable ink composition capable of forming a high-thickness image line, solid, halftone dot and the like (hereinafter referred to as “image line etc.”) having good properties.

  The aqueous ultraviolet curable ink composition of the present invention is an aqueous ultraviolet curable ink composition comprising at least a luster pigment, a photopolymerizable compound, a photopolymerization initiator, and water, and the photopolymerizable compound is at least It has one type of pentafunctional or higher functional photopolymerizable oligomer and at least one type of bifunctional urethane photopolymerizable oligomer, the photopolymerizable compound is 40 wt% to 68 wt%, and the photo polymerization initiator is 2 wt%. An aqueous ultraviolet curable ink composition characterized by comprising from 15% by weight to 15% by weight, from 5% by weight to 18% by weight of water, and from 5% by weight to 25% by weight of the glitter pigment.

  The aqueous ultraviolet curable ink composition of the present invention is an aqueous ultraviolet curable ink composition characterized in that the oligomer having five or more functional groups is urethane, epoxy, or ester photopolymerizable oligomer.

  In the aqueous ultraviolet curable ink composition of the present invention, a photopolymerizable compound having 5 or more functional photopolymerizable oligomers is 5 to 40% by weight, and a bifunctional urethane photopolymerizable oligomer is 20% by weight. % To 70% by weight of an aqueous ultraviolet curable ink composition.

  The aqueous ultraviolet curable ink composition of the present invention is an aqueous ultraviolet curable ink composition characterized in that the photopolymerizable compound further comprises at least one photopolymerizable monomer.

  In the aqueous ultraviolet curable ink composition of the present invention, 5 to 40% by weight of the photopolymerizable oligomer having 5 or more functional photopolymerizable compounds, and 20 to 20% by weight of the bifunctional urethane-based photopolymerizable oligomer. A water-based ultraviolet curable ink composition characterized by comprising from 70% by weight to 70% by weight of photopolymerizable monomer and from 0 to 60% by weight.

  The aqueous ultraviolet curable ink composition of the present invention is an aqueous ultraviolet curable ink composition characterized by having a viscosity at 30 ° C. of 0.5 Pa · s to 10 Pa · s.

  Further, the aqueous ultraviolet curable ink composition of the present invention is characterized by being used for producing a forgery-preventing printed material.

  The aqueous ultraviolet curable ink composition of the present invention is excellent in the leafing effect of the glitter pigment contained in the ink film having a high film thickness, has a high ink film strength, and has a high film thickness with good friction resistance. An image line or the like can be formed.

  Moreover, the water-based ultraviolet curable ink composition of the present invention does not require a separate drying device for evaporating moisture, and thus the equipment can be made compact.

  A mode for carrying out the present invention will be described. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical idea described in the claims.

  The present invention is an aqueous ultraviolet curable ink composition comprising at least a luster pigment, a photopolymerizable compound, a photopolymerization initiator and water, wherein the photopolymerizable compound is a photopolymerizable oligomer having five or more functional groups, An aqueous ultraviolet curable ink composition comprising a bifunctional urethane oligomer.

(Photopolymerizable compound)
Examples of the photopolymerizable oligomer having 5 or more functional groups include urethane oligomers, epoxy oligomers, and ester oligomers having a molecular weight of 2000 to 15000 and 5 or more photopolymerizable functional groups in one molecule. By using the oligomer, high film strength can be obtained.

  In addition, the blending ratio of the pentafunctional or higher functional photopolymerizable oligomer to the photopolymerizable compound is 5% by weight to 40% by weight. This is because if it is less than 5% by weight, sufficient film strength cannot be obtained. This is because if the amount exceeds 40% by weight, the elasticity of the ink film is lowered and becomes brittle.

  As a bifunctional urethane-based oligomer, for example, a urethane prepolymer is produced by reacting a polyol (a) with an organic polyisocyanate (b), and a hydroxyl group-containing (meth) acrylate (c) is reacted with the urethane prepolymer. There is something that can be obtained. Moreover, what is obtained by reacting organic polyisocyanate (b) and hydroxyl group-containing (meth) acrylate (c) can be exemplified. This is because by using such a bifunctional urethane oligomer, the elasticity of the ink film is improved and the ink film is prevented from becoming brittle.

  Examples of the polyol (a) include ethylene glycol, propylene glycol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexanediol, polypropylene glycol, bisphenol A polyethylene glycol, polytetramethylene glycol, glycerin, and trimethylol. Examples include propane, polyester polyol, polycarbonate polyol, polycaprolactone polyol, polybutadiene polyol, polymer polyol, and polysiloxane polyol.

  Examples of the organic polyisocyanate (b) include aromatic diisocyanates such as tolylene diisocyanate or diphenylmethane diisocyanate; araliphatic diisocyanates such as tetramethylxylylene diisocyanate, isophorone diisocyanate, bis (4-isocyanatocyclohexyl) methane, hexa Examples thereof include aliphatic or cycloaliphatic diisocyanates such as methylene diisocyanate and trimethylhexamethylene diisocyanate. Examples of the hydroxyl group-containing (meth) acrylate (c) include one acrylic group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Multifunctional having two or more acrylic groups such as functional (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, etc. (Meth) acrylate etc. can be mentioned.

  In addition, the mixture ratio of the bifunctional urethane type photopolymerizable oligomer with respect to a photopolymerizable compound is 20 to 70 weight%. If it is less than 20% by weight, it becomes a brittle ink film with no flexibility when a high-thickness image line is formed, and if it exceeds 70% by weight, it is a low-viscosity photopolymerizable compound or pentafunctional. This is because there is no physical property adjustment range in the oligomer.

  In addition, the photopolymerizable compound can be further strengthened by further blending a photopolymerizable monomer to improve ink flow characteristics and film physical properties. As the photopolymerizable monomer, known monofunctional or polyfunctional photopolymerizable monomers can be used alone or in combination of two or more.

  Examples of the monofunctional photopolymerizable monomer include (meth) acrylic acid, itaconic acid, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, and N, N-dimethyl (meth) acrylamide. N, N-diethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-ethylaminoethyl (meth) acrylamide, diacetone (meth) acrylamide, N-vinylpyrrolidone, N- (meth) acryloylpyrrolidone, 2- Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, glycerol (meth) acrylate, (methoxy) polyethylene glycol (meth) acrylate Etc. The.

  Examples of the bifunctional photopolymerizable monomer include triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6- Hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO (ethylene oxide) adduct of bisphenol A, PO (propylene oxide) adduct of bisphenol A Diacrylate, hydroxypivalate neopentyl glycol diacrylate, polytetramethylene glycol diacrylate, etc. It is.

  Examples of the trifunctional photopolymerizable monomer include triacrylate or trimethacrylate of trihydric or higher polyhydric alcohols such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate and the like. It is done.

  Examples of the tetra- or higher functional photopolymerizable monomer include tricyclodecane di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane polyethoxytri (meth) acrylate, trimethylolpropane polypropoxytri (meth) acrylate, glycerin polypropoxytri (meth) acrylate Bisphenol A polyethoxydi (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) ) Acrylate, dipentaerythritol penta and hexa (meth) acrylate mixture, dipentaerythritol polyethoxy hexa (meth) acrylate, dipentaerythritol poly propoxy hexa (meth) acrylate and the like. This is because the use of such an acrylic monomer improves the strength of the ink film and prevents the ink film from becoming brittle.

  In addition, the mixture ratio of the photopolymerizable monomer with respect to a photopolymerizable compound is 0 to 60 weight%. This is because if the amount exceeds 60% by weight, the ink film becomes brittle and is not suitable for forming a high-thickness image line or the like.

(Water-based UV curable ink composition)
The aqueous ultraviolet curable ink composition comprises at least the above-described photopolymerizable compound, a photopolymerization initiator, and water.

  The blending ratio of the photopolymerizable compound to the aqueous ultraviolet curable ink composition is 40% by weight to 68% by weight. If it is less than 40% by weight, there is a risk of causing poor curing. On the other hand, if it exceeds 68% by weight, the blending of water and other materials is insufficient, and it may not function as an aqueous ultraviolet curable ink.

  As a photoinitiator, a well-known photoinitiator can be used individually or in combination of 2 or more types. The blending ratio of the photopolymerization initiator to the aqueous ultraviolet curable ink composition is 2 to 15% by weight. If it is 2% by weight or less, curing failure occurs, and the kind and amount of pigment, the ink film thickness, and the like are limited. This is because when the content exceeds 15% by weight, there is no significant change in curability even when added.

  As the water, tap water, distilled water, ion-exchanged water or the like can be used, and there is no particular limitation as long as the contained impurities do not adversely affect the curability of the polymerizable compound pigment and the flow characteristics of the ink. The mixing ratio of water for obtaining the leafing effect of the glittering pigment needs to be in the range of 5 to 18% by weight. If it is less than 5% by weight, the viscosity of the ink cannot be lowered, and the leafing effect of the pearl pigment or the like is difficult to obtain. In addition, when it exceeds 18% by weight, the ink viscosity becomes excessively low and becomes 0.5 Pa · s or less, so that it is difficult to obtain a sufficient film thickness, and the film is cured by UV irradiation alone. It will be difficult. However, when there is no uniform moisture in the ink system, such as when there is a water-absorbing pigment such as calcium carbonate, calcium silicate, or barium sulfate, it is desirable to mix the absorbed water.

  The glitter pigment is not particularly limited as long as it is not soluble in water or a photopolymerizable compound. Known glitter pigments such as pearl pigments, scaly pigments, scaly mica, scaly metal pigments, glass flake pigments, and cholesteric liquid crystal pigments are used. Pigments can be used. Further, the particle size of the glitter pigment is, for example, an average size of 500 μm or less, preferably an average of 200 μm or less. The thickness of the glitter pigment is an average of 5 μm or less, preferably an average of 1 μm or less. This is because the orientation deteriorates when the upper limit is exceeded. In addition, the mixture ratio of a luster pigment is 5 to 25 weight%. If it is 5% by weight or less, sufficient saturation cannot be obtained when observing interference light after ink formation. This is because if the amount is 25% by weight or more, the effect corresponding to the blending ratio cannot be obtained, and the saturation is not further improved.

  Moreover, the well-known organic pigment and an inorganic pigment can be added to the aqueous ultraviolet curable ink composition of this invention as needed. Further, in order to improve the stability of the ink and the abrasion resistance of the ink film, an antifoaming agent, a leveling agent, an emulsifier, a polymerization inhibitor and a wax can be added. The ink viscosity is preferably 0.5 Pa · s to 10 Pa · s (30 ° C.). If it is less than 0.5 Pa · s, it is difficult to obtain a sufficient film thickness, and if it exceeds 10 Pa · s, the printability is inferior and reproducibility of image lines and the like is applied.

  In addition, the aqueous ultraviolet curable ink composition of the present invention can be printed on paper, plastic, film, metal plate and the like without any particular limitation on the substrate to be printed. Particularly preferred is a paper such as a coated paper having high smoothness and having an ink receiving layer. This is because the adhesion is improved when the ground contact area between the ink and the paper is large.

  In addition, the printing method on a base material such as paper using the aqueous ultraviolet curable ink composition of the present invention is not particularly limited, and an offset printing method, a gravure printing method, a screen printing method, a flexographic printing method, and A known printing method such as an intaglio printing method can be used. In consideration of anti-counterfeiting effects, printability, and high-thickness image lines, intaglio printing, screen printing, and flexographic printing are preferable.

  Moreover, since the water-based ultraviolet curable ink composition of the present invention can form a printed image line having a high film thickness, the first image line and the second image line are respectively obtained using the ink composition. It is used for printed matter (for example, Japanese Patent No. 4374446) that forms a background portion and a latent image portion at different angles, and the latent image can be visually recognized by tilting the printed matter. Even if it is used, a printed matter having a high anti-counterfeit effect equivalent to that of oil-based ink can be produced, which is favorable in terms of environment and occupational health.

  In addition, since the aqueous ultraviolet curable ink composition of the present invention forms a printed image line having a high film thickness that the glittering pigment leaves, interference light that is a unique effect of the glittering pigment can be obtained by slightly tilting the printed matter. (Iris color) can be generated. Therefore, using the ink, the first image line and the second image line are arranged at different angles to form a background portion and a latent image portion, and the printed image is tilted to form a latent image having an arbitrary gradation. Since it can be used for printed materials (for example, WO2003 / 013871 etc.) that can visually recognize images, and even if water-based inks are used, printed materials with a high anti-counterfeiting effect equivalent to oil-based inks can be produced. Also good for occupational health.

(Method for producing water-based ultraviolet curable ink composition)
The preparation method of the aqueous ultraviolet curable ink composition of the present invention comprises a photopolymerizable compound preparation step and a mixing and stirring step.

  In the photopolymerizable compound production step, at least one kind of pentafunctional or higher oligomer, at least one kind of bifunctional urethane oligomer, and a low viscosity photopolymerizable compound are mixed and heated and stirred. In addition, stirring can use well-known stirring apparatuses, such as a propeller stirrer and a Henschel mixer. In the aqueous ultraviolet curable ink composition preparation step, a photopolymerization initiator is blended with the prepared photopolymerizable compound, and the mixture is heated and stirred. After blending a photopolymerization initiator, a pigment and an additive such as distilled water and wax are blended and kneaded at room temperature with an ink production apparatus such as a propeller stirrer or a ball mill.

  For example, in the mixing and stirring step, when the photopolymerizable compound is hydrophilic, the photopolymerization initiator is sufficiently dispersed in the photopolymerizable compound by heating and stirring or kneaded meat. Next, a necessary amount of water, an auxiliary agent, a pigment, and the like are added and stirred sufficiently to complete a system. Furthermore, when blending pigments and auxiliaries, they are blended to such an extent that ink gelation does not occur, and stirring is performed. Examples of the highly hydrophilic aqueous photopolymerizable compound include an anion type in which a carboxyl group or a sulfonyl group is introduced, a cation type in which an amino group is neutralized with an acid or converted to a quaternary ammonium salt with a quaternizing reagent, Examples include nonionic type materials having an ether skeleton or a hydroxyl group. When an aqueous material is not used, a surfactant and a photopolymerization initiator are blended with the photopolymerizable compound, stirring is performed in the same manner as when the aqueous material is added, and a pigment and an auxiliary are blended.

  Hereinafter, the water-based ultraviolet curable ink composition of the present invention will be described in detail with specific examples. In addition,% in an example shows weight% altogether.

(Photopolymerizable compound A)
A propeller-type stirrer containing the pentafunctional urethane-based oligomer (manufactured by Nippon Kayaku Co., Ltd.), the bifunctional urethane-based oligomer (manufactured by Kyoeisha Chemical Co., Ltd.) and the monofunctional acrylic monomer (manufactured by Arakawa Chemical Industries) according to the formulation shown in Table 1. Then, the mixture was heated and stirred at a temperature of 70 ° C. for 40 minutes to prepare a photopolymerizable compound A.

(Photopolymerizable compound B)
Pentafunctional urethane oligomer (Nippon Kayaku Co., Ltd.), bifunctional urethane oligomer (Kyoeisha Chemical Co., Ltd.), monofunctional acrylic monomer (Arakawa Chemical Co., Ltd.), hexafunctional acrylic monomer (Nipponization) Yakuhin Co., Ltd.) was used, and the photopolymerizable compound B was prepared by heating and stirring with a propeller stirrer at a temperature of 70 ° C. for 40 minutes according to the formulation shown in Table 2.

(Water-based UV curable ink composition)
A photopolymerization initiator was added to the prepared photopolymerizable compounds A and B, and the mixture was heated and stirred at a temperature of 70 ° C. for 15 minutes. After stopping the heating, the pigment (manufactured by Merck Co.), using distilled water at room temperature by the formulation shown in Table 3, to prepare an aqueous ultraviolet-curable ink composition V ₁ and V ₂ and stirred with a propeller stirrer.

(Comparative photopolymerizable composition)
A bifunctional urethane oligomer (manufactured by Kyoeisha Chemical Co., Ltd.) and a monofunctional acrylic monomer (manufactured by Arakawa Chemical Industry Co., Ltd.) are used. Thus, a comparative photopolymerizable compound C was produced.

(Comparative UV-curable ink composition)
A photopolymerization initiator was added to the produced comparative photopolymerizable compound C, and the mixture was heated and stirred at a temperature of 70 ° C. for 15 minutes. After stopping the heating, the pigment (manufactured by Merck Co.), using distilled water at room temperature by the formulation of Table 5, to prepare a comparative aqueous UV-curable ink composition V ₃ was stirred with a propeller stirrer.

  The aqueous ultraviolet curable ink composition of the present invention was evaluated as follows.

  For printability, an actual screen printer was used, and after screen printing, the ink film was cured by irradiating with ultraviolet rays, and the friction resistance of the ink film was evaluated. The ink film was 10 μm. In the ultraviolet irradiation, the output of one 120 W / cm metal halide lamp was adjusted to 3.6 kw, the irradiation distance from the printed material was adjusted to 14 cm, and the conveyance speed of the printed material was set to 22 m / min.

The strength of the ink film was evaluated on the printed material using a Gakushin friction tester, and the degree of rub-off of the ink film on the surface of the printed material was evaluated in three stages according to the condition of 100 reciprocations of kanakin with a load of 500 g Good if there is no rubbing, good if there is almost no rubbing off, bad if the rubbing is severe x). The evaluation results are shown in Table 6.
×: Defect ○: Good ◎: Good

  As shown in Table 6, according to the examples of the present invention, it was possible to obtain an ink having excellent ultraviolet curability and excellent durability.

Claims (7)

An aqueous ultraviolet curable ink composition comprising at least a glitter pigment, a photopolymerizable compound, a photopolymerization initiator, and water,
The photopolymerizable compound has at least one type of pentafunctional or higher functional photopolymerizable oligomer and at least one type of bifunctional urethane photopolymerizable oligomer,
The photopolymerizable compound is 40 wt% to 68 wt%, the photopolymerization initiator is 2 wt% to 15 wt%, the water is 5 wt% to 18 wt%, and the glitter pigment is 5 wt%. To 25% by weight of an aqueous ultraviolet curable ink composition.   The aqueous ultraviolet curable ink composition according to claim 1, wherein the photopolymerizable oligomer having five or more functional groups is a urethane-based, epoxy-based, or ester-based photopolymerizable oligomer.   The photopolymerizable compound has 5 to 40% by weight of the photopolymerizable oligomer having 5 or more functional groups, and 20 to 70% by weight of the bifunctional urethane-based photopolymerizable oligomer. The aqueous ultraviolet curable ink composition according to claim 1 or 2.   4. The aqueous ultraviolet curable ink composition according to claim 1, wherein the photopolymerizable compound further comprises at least one photopolymerizable monomer. 5.   The photopolymerizable compound includes 5 to 40% by weight of the photopolymerizable oligomer having 5 or more functional groups, and 20 to 70% by weight of the bifunctional urethane-based photopolymerizable oligomer. 5. The aqueous ultraviolet curable ink composition according to claim 4, wherein the monomer content is more than 0% by weight and 60% by weight or less.   The aqueous ultraviolet curable ink composition according to any one of claims 1 to 5, wherein the viscosity at 30 ° C is from 0.5 Pa · s to 10 Pa · s.   Use of the aqueous ultraviolet curable ink composition according to claim 1 for anti-counterfeit printed matter.