JP2008056771A - Photocurable type ink composition for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable ink composition exhibiting an excellent close adhesion in printing on various plastics, glasses and metal media, and also capable of obtaining a printed matter excellent in hardness and scratch resistance, and the printed matter printed by using the same. <P>SOLUTION: This photocurable type ink composition contains (P) 2 to 50 pts.wt. acrylic polymer containing hydroxy group of 1 to 200 mgKOH/g hydroxy value and having 1,000 to 100,000 molecular weight, (M) 50 to 98 pts.wt. radically polymerizable compound and (C) 0.1 to 15 pts.wt. photo polymerization initiator based on 100 pts.wt total of the (P) and (M). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a photocurable ink composition for printing that can be cured by ultraviolet rays, electron beams, radiation, and the like. More specifically, a photocurable ink composition for printing that exhibits excellent adhesion to plastic, glass, and metal surfaces, and that can perform printing with excellent hardness and scratch resistance, and printed by the same. It is printed matter.

  Printing methods include relief printing such as flexographic printing and dry offset printing, intaglio printing such as gravure printing and gravure offset printing, lithographic printing such as offset printing, and stencil printing such as screen printing. In recent years, a printing method called ink jet printing, in which droplets of an ink composition are ejected and attached to a recording medium such as paper, is also used. The ink composition used for the ink jet recording method is generally composed of an aqueous solvent as a main component and a coloring component and a wetting agent such as glycerin for the purpose of preventing clogging. Paper, fabrics, or materials that do not penetrate easily, such as plastic, glass, metal, etc., such as acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, polybutylene When printing on recording media such as terephthalate (PBT) resin, fiber reinforced composite material (FRP), polymethylmethacrylate (acrylic) resin, and plastics such as vinyl chloride, the ink composition , It must contain components that can be stably fixed to the recording medium It is. Such a demand is not limited to ink jet printing, and there is a strong demand in any printing method.

In response to such demands, ultraviolet curable inks containing ultraviolet curable materials (polymerizable compounds), photopolymerization initiators, and the like have begun to be used, and ultraviolet curable inks have also been disclosed for inkjet inks. (Patent Document 1). According to this ink, it is said that the ink can be prevented from bleeding into the recording medium and the image quality can be improved. However, the ultraviolet curable ink described in Patent Document 1 has poor adhesion to a substrate, and is not an ink that adheres widely to substrates such as various plastics, glass, and metals. Moreover, since water is used as a solvent, the wettability with respect to various base materials is poor, and this is also a factor of lowering the adhesion.
Furthermore, an actinic ray curable inkjet solventless ink containing a specific acrylate compound, which is particularly effective in the case of a non-absorbing recording material such as a plastic film, is disclosed (Patent Document 2). When printed on a PP or PET film, wrinkles / curls, character quality, and color mixing have been improved, but adhesion to various substrates and scratch resistance of printed matter were insufficient.
US Pat. No. 5,562,001 Japanese Patent Application Laid-Open No. 2004-175906

  In view of the above-mentioned present situation, the present invention provides a printed material that exhibits excellent adhesion, and has excellent hardness and scratch resistance when printed on various plastic, glass, and metal media. It aims at providing a photocurable ink composition and its printed matter.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the present invention contains 2 to 50 parts by weight of an acrylic polymer (P) having a hydroxyl value of 1 to 200 mg KOH / g and a molecular weight of 1,000 to 100,000, and a radical polymerizable compound (M) 50. The photocurable ink composition for printing, comprising 0.1 to 15 parts by weight of the photoinitiator (C) with respect to -98 parts by weight and 100 parts by weight of the total of (P) and (M) It is a thing. Moreover, it is preferable that 1-100 weight part of urethane acrylate (U) is contained in a radically polymerizable compound (M) in 100 weight part. Moreover, it is a printed matter obtained by printing the photocurable ink composition for printing of this invention, and also irradiating this with an ultraviolet-ray and hardening an ink composition.

  According to the present invention, when printed on various plastics, glass, and metal media, a printed matter exhibiting excellent adhesion and excellent in hardness and scratch resistance can be obtained.

The present invention will be described in detail below.

<< Acrylic polymer (P) >>
The acrylic polymer (P) in the present invention contains at least one monomer selected from acrylic acid ester and methacrylic acid ester in order to express excellent adhesion and scratch resistance. It is an acrylic polymer that is polymerized by containing 50% by weight or more in the coalescence (P). The acrylic polymer (P) of the present invention can be obtained by copolymerizing a monomer (a) containing a hydroxyl group and another monomer (b).
Examples of the monomer (a) containing a hydroxyl group include hydroxyl group-containing vinyls such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Here, description like methyl (meth) acrylate shows methyl acrylate and / or methyl methacrylate, and the following (meth) has the same meaning.

 Examples of the other monomer (b) include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n -Amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) ) Acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanylmeth) acrylate, dicyclopentenyl (meth) acrylate, Alkyl (meth) acrylates such as cyclopentenyloxyethyl (meth) acrylate; aromatic resins such as styrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene and divinylbenzene; acrylic Unsaturated carboxylic acids such as acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and anhydrides thereof; acrylamide, methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic amide, etc. Amides; vinyl esters such as vinyl acetate and vinyl propionate; vinylidene halides such as vinylidene chloride and vinylidene fluoride; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylamino Chill (methacrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dihydroxyethylaminoethyl Aminoalkyl (meth) acrylates such as (meth) acrylate; Unsaturated sulfonic acids such as styrene sulfonic acid, sodium styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid; mono (2-methacryloyloxyethyl) acid Unsaturated phosphoric acids such as phosphate and mono (2-acryloyloxyethyl) acid phosphate; 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether , Acrylonitrile, methacrylonitrile, vinyl chloride, ethylene, propylene, isoprene, butadiene, chloroprene, vinyl pyrrolidone, 1,2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate, 2,2,6,6 -Tetramethyl-4-piperidyl (meth) acrylate, 2- (2'-hydroxy-5'-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.

Among these, as other monomer (b), in order to obtain good adhesion, the carbon number of alkyl such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc. is 4 or less. The alkyl (meth) acrylates are preferably used.
The acrylic polymer (P) in the present invention usually contains a hydroxyl group having a hydroxyl value of 1 to 200 mgKOH / g, preferably 10 to 180 mgKOH / g, more preferably 20 in order to develop adhesion and hardness. It contains ˜160 mg KOH / g hydroxyl group.

  Further, the molecular weight of the acrylic polymer (P) in the present invention is usually 1,000 to in order to express good hardness and scratch resistance, and to make the viscosity of the ink composition in a printable range. 100,000, preferably 3,000-60,000, more preferably 5,000-30,000.

<< Radically polymerizable compound (M) >>
The radical polymerizable compound (M) in the present invention is a compound having an acrylic group. For example, ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dipropylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentenyl (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane Diol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, neopen Diglycol-modified trimethylolpropane di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, bis ((meth) acryloxyethyl) bisphenol A, tri Methylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane ditri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, ethylene oxide modified glycerol tri (meth) acrylate, propylene Oxide-modified glycerin tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythrine Lithol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, part of these (meth) acrylates substituted with alkyl groups or ε-caprolactone Examples thereof include polyfunctional (meth) acrylate, acryloylmorpholine having an active double bond, triethylene glycol divinyl ether, hydroxyethyl divinyl ether, styrene, divinylbenzene and the like.

 Furthermore, polyester poly (meth) acrylates obtained by reaction of polybasic acids such as phthalic acid and adipic acid, polyhydric alcohols such as ethylene glycol and butadiol, and (meth) acrylic acid compounds; epoxy resins and (meth ) Epoxy poly (meth) acrylate obtained by reaction with acrylic acid compound; Polysiloxane poly (meth) acrylate obtained by reaction of polysiloxane and (meth) acrylic acid compound; Polyamide and (meth) acrylic acid compound Examples thereof include polyamide poly (meth) acrylate obtained by the reaction.

  In the present invention, one or more radical polymerizable compounds (M) are applied according to the desired hardness and scratch resistance of the coating film, but urethane acrylate (U), trimethylolpropane tri (meth) acrylate, Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified trimethylolpropane ditri (meth) acrylate, tripropylene glycol di (meth) acrylate, dipentaerythritol penta (Meth) acrylate and dipentaerythritol hexa (meth) acrylate are preferably used.

Among these, in order to obtain a coating film particularly excellent in scratch resistance, it is preferable to contain urethane acrylate (U) having an acrylic group in the urethane resin as the radical polymerizable compound (M). The content of is usually 1 to 100 parts by weight, preferably 50 to 100 parts by weight, and more preferably 70 to 100 parts by weight in 100 parts by weight of the radical polymerizable compound (M). Urethane acrylate (U) is synthesized by polymerization by addition reaction of a diisocyanate compound and a glycol species, and further adding (meth) acrylate having an active hydrogen group such as a hydroxyl group to the remaining isocyanate group.
Examples of the diisocyanate compound include hexamethylene diisocyanate (HDI), 1,3-diisocyanatomethylcyclohexane (H ₆ XDI), isophorone diisocyanate (IPDI), and toluene diisocyanate (TDI). Of these, HDI, H ₆ XDI, and IPDI are preferred.

Examples of the glycol species include polyester polyols such as pivalic acid neopentyl glycol ester and polycaprolactone polyol; polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol; polycarbonate polyols such as polyhexamethylene carbonate glycol; Ethylene glycol, propanediol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,6-hexanediol, methylpentanediol, neopentylglycol, 3,3-dimethylolheptane, Alkanediol having 7 to 22 carbon atoms, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexane dimeta Alcohol, alkane-1,2-diol having 17 to 20 carbon atoms, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,8-diol, bisphenol A, glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, 1,1,1-tris (hydroxy Methyl) propane, 2,2-bis (hydroxymethyl) -3-butanol, other aliphatic triols having 8 to 24 carbon atoms, tetramethylolmethane, D-sorbitol, xylitol, D-mannitol, D-mannitol, etc. It is. Among these, polyester polyols such as polycaprolactone polyol and polyether polyols such as polytetramethylene ether glycol are preferable.
Furthermore, examples of (meth) acrylates having active hydrogen groups such as hydroxyl groups include hydroxyl group-containing vinyls such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Can be mentioned.

<< Photoinitiator (C) >>
The photoinitiator (C) of the present invention is a compound capable of generating radicals by ultraviolet rays, electron beams, radiation, etc., and specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether. , Benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4 -Bis (dimethylaminobenzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy- Carbonyl compounds such as methylpropan-1-one; sulfur compounds such as tetramethylthiuram disulfide; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; anthraquinones such as 2-ethylanthraquinone Peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide; acyls such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide A phosphine oxide compound can be mentioned.

  Examples of preferred initiators include benzophenone, methylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine These are oxides, and these may be used alone or in combination of two or more.

The ratio of the acrylic polymer (P) of the present invention to the radical polymerizable compound (M) is a cured product that exhibits excellent adhesion on a plastic, glass or metal surface, and has excellent hardness and scratch resistance. In order to obtain a coating film, usually 2 to 50 parts by weight of the acrylic polymer (P), 50 to 98 parts by weight of the radical polymerizable compound (M), preferably 2 to 40 parts by weight of (P), and 60 to (M). 98 parts by weight, more preferably (P) 2 to 30 parts by weight, (M) 70 to 98 parts by weight.
The ratio of the photoinitiator (C) is usually 0.1 to 15 parts by weight, preferably 1 to 10 parts by weight, more preferably 100 parts by weight of the total of (P) and (M). 1 to 8 parts by weight.

In the photocurable ink composition for printing of the present invention, a coloring material, a dye, a pigment, an organic solvent, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, a yellowing inhibitor, a leveling agent, and an antifoaming agent. Various additives such as a thickener, an anti-settling agent, an antistatic agent, an antifogging agent, an anti-fogging agent, a wetting agent, a dispersing agent, an anti-sagging agent, and a coupling agent can be contained.
Printing methods include relief printing such as flexographic printing, dry offset printing, intaglio printing such as gravure printing and gravure offset printing, lithographic printing such as offset printing, stencil printing such as screen printing, and inkjet printing. It is done. In order to enable printing, the viscosity at 25 ° C. is preferably 5 to 200 mPa · s. For this purpose, adjustment can be performed by adding an organic solvent or a radical polymerizable compound (M).

Moreover, a known method can be used for irradiation with active energy rays such as ultraviolet rays, electron beams, and radiations, and ultraviolet lamps are generally used as a generation source in terms of practicality and economy. Specific examples include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a gallium lamp, a metal halide lamp, and ultraviolet rays such as sunlight. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon. Further, ultraviolet irradiation can be performed by an ultraviolet light emitting semiconductor element such as an ultraviolet light emitting diode (ultraviolet LED) or an ultraviolet light emitting semiconductor laser. The irradiation amount of ultraviolet rays in a range of ^{100mJ / cm 2 ~1000mJ / cm 2} .
Moreover, you may heat before ultraviolet irradiation, simultaneously, or after that. Examples of the heating include a method of heating a recording medium by bringing it into contact with a heat source, a method of heating without contacting the recording medium, such as irradiation with infrared rays or microwaves (electromagnetic waves), or blowing hot air.

  Examples of the plastic that is the base material include various synthetic resin molded products. Specific examples of synthetic resin molded products include acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, fiber reinforced composite material (FRP), Polyester resin, polymethyl methacrylic resin, polystyrene resin, polyolefin resin, acrylonitrile-styrene copolymer resin, polyamide resin, polyarylate resin, polymethacrylimide resin, polyallyl diglycol carbonate resin, and the like. These are sheet-like molded products made of resin, film-shaped molded products, various injection-molded products, and the like.

In addition, examples of the metal include iron, aluminum, stainless steel, zinc, and alloys thereof, and further, a metal deposition base material formed by using a method such as vapor deposition, sputtering, ion plating, or plating of the metal. . Examples of the metal used for these include Al, Zn, Cu, Ag, Au, Sn, Ni, and alloys thereof.
Furthermore, the base material which consists of glass is mentioned, The glass product which has shapes, such as a bottle and a container other than on a board, is mentioned.
The photocurable ink composition for printing according to the present invention can produce a printed matter that exhibits excellent adhesion and has excellent hardness and scratch resistance when printed on various plastics, glass, and metal media. it can.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
[Example 1]
Into a reaction vessel charged with 85 g of toluene and 37 g of n-butanol, a mixed solution of 85 g of methyl methacrylate (MMA), 14 g of 2-hydroxyethyl methacrylate (HEMA), 1 g of methacrylic acid (MAA) and 2 g of azobisisobutyronitrile. The solution was added dropwise at 100 ° C. for 4 hours under a nitrogen stream. Furthermore, in order to maintain 100 degreeC and to complete polymerization, 0.2 g of azobisisobutyronitrile was added twice every hour. The mixture was cooled 3 hours after the completion of the dropping to obtain an acrylic polymer (P) solution having a nonvolatile content of 45% and a weight average molecular weight of 15000.
Further, 11.1 g of this polymer solution (5 g of polymer) was added to 31 g of olestar RA1574 (manufactured by Mitsui Chemicals: urethane acrylate), 13 g of neopentyl glycol diacrylate (NPG-A), 1,6-hexanediol diacrylate ( HDDA) 51 g and Irgacure 184 (Ciba Specialty Photoinitiator) 3 g were mixed to obtain a transparent photocurable ink composition having a viscosity at 25 ° C. of 13.5 mPa · s.

[Examples 2, 3, 4, 5, 6, 7, 8]
Photocurable ink was prepared by the same operation as in Example 1, except that the monomer type constituting the acrylic polymer (P) and the type and mixing ratio of the radical polymerizable compound (M) were changed as shown in Table 1. A composition was obtained. The acrylic polymer (P) used in Example 6 was prepared by adjusting the amount of azobisisobutyronitrile shown in Example 1 to 1 g.

[Comparative Examples 1, 2, 3, 4]
The monomer species constituting the polymer (P) and the type and mixing ratio of the radical polymerizable compound (M) were changed as shown in Table 1, and the operations of Comparative Examples 1 and 2 were carried out in the same manner as in Example 1. A photocurable ink composition was obtained.

[Evaluation methods]
The photocurable ink composition obtained above was tested by the following method. The results are shown in Tables 1-3.
<Measurement of molecular weight>
The molecular weight of the acrylic polymer (P) was measured with a RI detector using GPC (Shodex GPC SYSTEM-11: Showa Denko).
<Measurement of hydroxyl value>
The hydroxyl value was evaluated according to JIS K0070.
<Measurement of viscosity>
The viscosity at 60 rpm was measured according to JIS K7117-1 at a temperature of 25 ° C.
<Printing conditions, UV irradiation conditions>
The prepared ink composition is printed on various substrates with an inkjet printer JET HQL type (manufactured by Kishu Giken Kogyo Co., Ltd.), dried at 60 ° C. for 1 min, and then irradiated with an ultraviolet irradiation device having three 100 w / cm high-pressure mercury lamps. Ultraviolet rays were irradiated at 10 cm and a line speed of 10 m / min. The test piece thus obtained was subjected to subsequent tests.
<Base material>
For printing, a PET (polyethylene terephthalate) plate, a PMMA (polyacrylic) plate, a PC (polycarbonate) plate, an ABS (acrylonitrile-butadiene-styrene copolymer) plate, an aluminum plate, and a glass plate were used as substrates.
<Adhesion>
The adhesion was evaluated by a cross cut test (JIS K5600-5-6). 100/100 is the case where everything is not peeled off, and 0/100 is the case when it is all peeled off.
<Hardness>
The pencil hardness was evaluated according to (JIS K5600-5-6) using a test plate printed on an ABS substrate.
<Abrasion resistance>
With the test plate printed on the ABS base material, the change in the printing state was examined with a load of 250 g and 50 rotations with a CS-10F wear wheel by the Taber abrasion test method (JIS K5600-5-9). ◎ good appearance, ○ slightly scratched coating film, △ scratched and whitened coating film, × scratched and completely unseen base It was.
[Evaluation results]

According to the present invention, it is possible to obtain an ink composition and a printed matter that exhibit excellent adhesion and are excellent in hardness and scratch resistance when printed on various plastics, glass, and metal media.

Claims (3)

2-50 parts by weight of an acrylic polymer (P) having a hydroxyl value of 1-200 mgKOH / g and a molecular weight of 1,000-100,000; and 50-98 parts by weight of the radical polymerizable compound (M) And 0.1 to 15 parts by weight of the photoinitiator (C) with respect to 100 parts by weight of the total of (P) and (M). The photocurable ink composition for printing according to claim 1, wherein the radical polymerizable compound (M) contains 1 to 100 parts by weight of urethane acrylate (U) in 100 parts by weight. A printed matter obtained by printing the photocurable ink composition for printing according to claim 1 or 2 on a plastic, glass or metal substrate, and further irradiating it with ultraviolet rays to cure the ink composition.