JP7797793B2 - Active energy ray-curable resin composition, method for producing same, and printed matter - Google Patents

Description

The present invention relates to a novel and useful active energy ray-curable resin composition and a method for producing it. More specifically, the present invention relates to an active energy ray-curable resin composition that has excellent curing properties and can be widely used as a variety of coating materials, including printing inks.

In recent years, growing demand for shorter printing turnaround times and environmental friendliness has led to the widespread use of quick-drying, solvent-free actinic ray-curable inks, replacing the traditional oil-based inks. Actinic ray-curable inks contain actinic ray-curable unsaturated compounds, such as acrylic ester compounds, as components. They cure instantly upon exposure to actinic rays, forming a tough film through three-dimensional crosslinking of the unsaturated compounds. Because they cure instantly, post-processing can be carried out immediately after printing. Therefore, actinic ray-curable inks are ideal for use in packaging printing and commercial form printing, where a strong film is required to improve productivity and protect designs.

Unsaturated compounds used in actinic radiation-curable inks include acrylic ester compounds obtained by reacting polyols with acrylic acid, and oligomers such as polyester acrylate and polyurethane acrylate. Further improvements in productivity are required, and in order to accelerate curing speed, resins in which acrylic groups are introduced into high-molecular-weight resins with high Tg are also being considered. For example, Patent Documents 1 to 3 disclose resins in which acrylic groups are introduced into polyester polyols via isocyanate compounds. In Patent Document 1, no trivalent or higher alcohols are used in the synthesis of the polyester polyol. In Patent Document 2, the ratio of OH contained in the alcohol to COOH contained in the monobasic acid and polybasic acid (OH/COOH) is less than 1.10. Furthermore, Patent Document 3 does not disclose a ratio of trivalent or higher alcohols of 13.0 mol% or more relative to the total amount of alcohol used. This limits the amount of acrylic groups introduced into the resin, so further introduction of acrylic groups to improve curing properties is required.

Furthermore, compared to oil-based inks, actinic ray-curable inks have poor ink fluidity, which can cause problems such as ink not being scraped off the ink fountain by the roller during printing (ink fountain run-out), and low dot gain in printed materials, resulting in reduced print reproducibility.

Japanese Patent Application Publication No. 7-286019 Japanese Patent Application Laid-Open No. 2001-348516 Japanese Patent Application Laid-Open No. 2020-90603

The present invention aims to provide an actinic radiation-curable ink that improves curability, eliminates ink fountain leakage problems during printing, and improves dot gain in printed materials, as well as to provide a resin composition for use in said ink.

The inventors discovered that an active energy ray-curable resin rich in acrylic groups can be obtained by reacting a polyester resin rich in hydroxyl groups, an isocyanate compound, and a hydroxyl group-containing acrylic compound, and that an active energy ray-curable resin composition containing this resin can provide inks and the like with excellent curability and fluidity, leading to the present invention.

That is, the first aspect of the present invention is
a resin (A) obtained by reacting a hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3);
and polyfunctional acrylic compound (B)
An active energy ray-curable resin composition comprising:
the hydroxyl group-containing polyester resin (a1) is a resin obtained by reacting a polyhydric alcohol containing a trihydric or higher alcohol with a polybasic acid in an OH/COOH molar ratio of 1.10 to 2.20, and the trihydric or higher alcohol is reacted in a proportion of 13 mol % or more relative to the total polyhydric alcohol;
the hydroxyl value of the hydroxyl-containing polyester resin (a1) is 50 or more,
The present invention relates to an active energy ray-curable resin composition, characterized in that the weight-average molecular weight of the hydroxyl group-containing polyester resin (a1) is 3,000 or more.

The second aspect of the present invention is
The present invention relates to the active energy ray-curable resin composition according to the first invention, wherein the isocyanate compound (a2) is a diisocyanate compound having two isocyanate groups.

The third aspect of the present invention is
The present invention relates to the active energy ray-curable resin composition according to either the first or second invention, which is an ink composition.

The fourth aspect of the present invention is
The present invention relates to a method for producing an active energy ray-curable resin composition according to any one of the first to third inventions, characterized in that a hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3) are reacted in a polyfunctional acrylic compound (B) to obtain a resin (A).

The fifth aspect of the present invention is
The present invention relates to a printed matter obtained by printing the active energy ray-curable resin composition according to any one of the first to third inventions on a substrate.

The present invention provides an actinic ray-curable ink that improves curability, eliminates ink fountain leakage problems during printing, and improves dot gain in printed materials, as well as a resin composition for use in said ink. The actinic ray-curable resin composition of the present invention can be used in a wide range of applications and is extremely useful industrially.

Embodiments of the present invention are described in detail below. However, the present invention is not limited to the embodiments described below, and various modifications are possible within the scope of the gist of the present invention.

In this invention, active energy rays refer to the energy required to excite the starting material of the curing reaction from the ground state to the transition state, and active energy rays in this invention refer to ultraviolet rays and electron beams.

The active energy ray-curable resin composition of the present invention comprises a resin (A) and a polyfunctional acrylic compound (B). The resin (A) is obtained by reacting a hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3).
The resin (A) of the present invention is a resin having a complex structure obtained by reacting a hydroxyl group-containing polyester, an isocyanate compound, and a hydroxyl group-containing acrylic compound, and since it is impossible or not practical to represent it by a general formula (structure), it will be described by its production method.

(Hydroxyl Group-Containing Polyester Resin (a1))
The hydroxyl-containing polyester resin (a1) used in the present invention is a resin obtained by reacting a polyhydric alcohol containing a trihydric or higher alcohol with a polybasic acid at an OH/COOH molar ratio of 1.10 to 2.20. Here, OH refers to the number of moles of hydroxyl groups in the polyhydric alcohol, and COOH refers to the number of moles of carboxyl groups theoretically capable of reacting with the alcohol. For example, in the case of 1 mole of carboxylic dianhydride, the COOH is 2 moles.

By using a trihydric or higher alcohol and reacting the polyhydric alcohol with a polybasic acid at an OH/COOH molar ratio in the range of 1.10 to 2.20, it is possible to introduce a large number of hydroxyl group terminals into the polyester resin (a1), which then allows for the introduction of a large number of active energy ray-curable acrylic groups in the subsequent reaction with the isocyanate compound (a2) and the hydroxyl group-containing acrylic compound (a3). To introduce sufficient hydroxyl groups, the trihydric or higher alcohol is preferably present in an amount of 13 mol% or more, and more preferably 20 mol% to 50 mol% of the total polyhydric alcohol. If it exceeds 50 mol%, gelation is likely to occur during the synthesis of the polyester resin (a1). However, by using a monobasic acid such as benzoic acid in combination, it is possible to use a trihydric or higher alcohol in an amount of 50 mol% or more, based on the total polyhydric alcohol.

Trivalent or higher polyhydric alcohols include, but are not limited to, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, sorbitan, sorbitol, dipentaerythritol, inositol, and tripentaerythritol.

Dihydric alcohols can also be used as polyhydric alcohols. Dihydric alcohols are not particularly limited and include linear alkylene dihydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, and 1 1,7-heptanediol, 1,8-octanediol, 1,2-octanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,12-dodecanediol, 1,2-dodecanediol, 1,14-tetradecanediol, 1,2-tetradecanediol, 1,16-hexadecanediol, 1,2-hexadecanediol, and the like are branched alkylene dihydric alcohols. Examples of cyclic alkylene dihydric alcohols include 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-dimethylpentanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, dimethylol octane, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, and 2,4-diethyl-1,5-pentanediol; and examples of cyclic alkylene dihydric alcohols include 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cycloheptanediol, tricyclodecane dimethanol, and hydrogenated bisphenol A. Examples include hydrogenated bisphenol F, hydrogenated bisphenol S, hydrogenated catechol, hydrogenated resorcinol, hydrogenated hydroquinone, as well as polyether polyols and polyester polyols such as polyethylene glycol (n = 2 to 20), polypropylene glycol (n = 2 to 20), and polytetramethylene glycol (n = 2 to 20).

Polybasic acids are not particularly limited and include, but are not limited to, aliphatic polybasic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, azelaic acid, dodecenylsuccinic acid, pentadecenylsuccinic acid, and other alkenylsuccinic acids; aromatic polybasic acids such as isophthalic acid, isophthalic acid, terephthalic acid, himic acid, 3-methylhimic acid, 4-methylhimic acid, trimellitic acid, pyromellitic acid, 1,8-naphthalic acid, and their anhydrides; and alicyclic polybasic acids such as 1,2,3,6-tetrahydrophthalic acid, 3-methyl-1,2,3,6-tetrahydrophthalic acid, 4-methyl-1,2,3,6-tetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, and their anhydrides.

In the reaction of the polyfunctional alcohol with the polybasic acid, a monohydric alcohol or a monobasic acid can also be used in combination.
Examples of monohydric alcohols include n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, isopentyl alcohol, amyl alcohol, tert-pentyl alcohol, cyclohexyl alcohol, benzyl alcohol, and α-phenylethyl alcohol.

Monobasic acids include benzoic acid, methylbenzoic acid, t-butylbenzoic acid, naphthoic acid, orthobenzoylbenzoic acid, propionic acid, butyric acid, α-methylbutyric acid, valeric acid, and cyclohexanecarboxylic acid.

In addition, hydroxy acids such as lactic acid and 12-hydroxystearic acid, and cyclic esters such as caprolactone can also be used in combination.

Hydroxyl group-containing polyester resin (a1) can be easily obtained by heating the above-mentioned polyhydric alcohol and polybasic acid in a conventional manner and subjecting them to a dehydration condensation reaction. The polyhydric alcohol and polybasic acid are reacted at an OH/COOH molar ratio in the range of 1.10 to 2.20, with a range of 1.10 to 1.50 being more preferable. If the ratio is less than 1.10, the number of terminal hydroxyl groups will be reduced, and if it exceeds 2.20, the molecular weight will be difficult to elongate, which is undesirable.

While the condensation reaction proceeds without a catalyst, a catalyst such as sulfuric acid, paratoluenesulfonic acid, or methanesulfonic acid may be used. If necessary, an appropriate solvent such as xylene may also be used. The weight-average molecular weight of the polyester resin (a1) is preferably 3,000 to 100,000, and more preferably 5,000 to 20,000. If the weight-average molecular weight is less than 3,000, the effect of improving curability tends to be small. If it exceeds 100,000, the viscosity of the final active energy ray-curable resin composition tends to increase, which is undesirable. Furthermore, the hydroxyl value of the polyester resin (a1) is preferably 50 or greater. If it is less than 50, the reaction of the hydroxyl group-containing acrylic compound (a3) via the isocyanate compound (a2) does not proceed sufficiently, which is undesirable, resulting in a small effect of improving curability.

(Isocyanate compound (a2))
The isocyanate compound (a2) is not particularly limited, and examples thereof include tolylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, and methylene diisocyanate. , 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate in which the carboxyl group of a dimer acid is converted to an isocyanate group. From the viewpoint of reaction control, bifunctional diisocyanates are preferred.

(Hydroxyl group-containing acrylic compound (a3))
The hydroxyl group-containing acrylic compound (a3) is not particularly limited, and examples thereof include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyethylene glycol acrylate, caprolactone-modified 2-hydroxyethyl acrylates, glycerin acrylate, glycerin diacrylate, diglycerin diacrylate, diglycerin triacrylate, trimethylolpropane acrylate, trimethylolpropane diacrylate, ditrimethylolpropane diacrylate, ditrimethylolpropane triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, and dipentaerythritol pentaacrylate.

(Resin (A))
The resin (A) is obtained by reacting the above-mentioned hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3).
The reactions of the hydroxyl-containing polyester resin (a1), the isocyanate compound (a2), and the hydroxyl-containing acrylic compound (a3) may be carried out simultaneously, or the isocyanate compound (a2) and the hydroxyl-containing acrylic compound (a3) may be reacted in advance, followed by the reaction of the hydroxyl-containing polyester resin (a1). Hydroxyl-containing polyester resins (a1) may also be reacted with each other using the isocyanate compound (a2), which is preferred when used in inks requiring viscoelasticity. The molar ratio NCO/OH of the total hydroxyl groups in the polyester resin (a1) and the hydroxyl-containing acrylic compound (a3) to the isocyanate groups in the isocyanate compound (a2) is preferably 1 or less. The reaction proceeds without a catalyst, but a catalyst can also be used. Usable catalysts include, for example, tertiary amine catalysts such as triethylamine and dimethylaniline, and metal catalysts such as tin and zinc. Furthermore, the reaction can be carried out in a solvent as needed, but it can also be carried out in a polyfunctional acrylic compound (B) described below, which is preferable because it can omit the steps of dissolving the resin (A) in the polyfunctional acrylic compound and removing the solvent.

(Polyfunctional Acrylic Compound (B))
The content of the polyfunctional acrylic compound (B) used in the present invention is 10 to 90% by weight, preferably 40 to 80% by weight, based on the total weight of the composition, and the content of the radical polymerization inhibitor is 0.01 to 5% by weight, preferably 0.1 to 1% by weight.

The polyfunctional acrylic compound (B) is not particularly limited and may be ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate (n = 2 to 20), propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate (n = 2 to 20), alkane (carbon number 4 to 12) glycol di(meth)acrylate, alkane (carbon number 4 to 12) glycol ethylene oxide adduct (2 to 20 mol) di(meth)acrylate, alkane (carbon number 4 to 12) glycol propylene oxide adduct (2 to 20 mol) di(meth)acrylate, hydroxypivalyl hydroxypivalyl Bifunctional acrylic compounds such as bisphenol A di(meth)acrylate, tricyclodecane dimethylol di(meth)acrylate, bisphenol A ethylene oxide adduct (2 to 20 mol) di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol A ethylene oxide adduct (2 to 20 mol) di(meth)acrylate, glycerin tri(meth)acrylate, glycerin ethylene oxide adduct (3 to 30 mol) tri(meth)acrylate, glycerin propylene oxide adduct (3 to 30 mol) tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene trifunctional acrylic compounds such as trimethylolpropane propylene oxide adduct (3 to 30 mol) tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethylene oxide adduct (4 to 40 mol) tetra(meth)acrylate, pentaerythritol propylene oxide adduct (4 to 40 mol) tetra(meth)acrylate, diglycerin tetra(meth)acrylate, pentaerythritol ethylene oxide adduct (4 to 40 mol) tetra(meth)acrylate, pentaerythritol propylene oxide adduct Examples of tetrafunctional or higher acrylic compounds include (4 to 40 mol) tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane ethylene oxide adduct (4 to 40 mol) tetra(meth)acrylate, ditrimethylolpropane propylene oxide adduct (3 to 30 mol) tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol ethylene oxide adduct (6 to 60 mol) hexa(meth)acrylate, and dipentaerythritol propylene oxide adduct (6 to 60 mol) hexa(meth)acrylate, as well as mixtures thereof.

In the active energy ray-curable resin composition of the present invention, an active energy ray-curable compound other than the polyfunctional acrylic compound (B) or an additive such as a radical polymerization inhibitor can be appropriately selected depending on the required physical properties of the cured coating film. For example, a monofunctional acrylic compound, a vinyl compound, or an active energy ray-curable oligomer can be used.
Examples of monofunctional acrylic compounds include 2-ethylhexyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, and acryloylmorpholine.
Examples of the vinyl compound include N-vinylpyrrolidone and divinylbenzene.
Examples of the active energy ray-curable oligomer include polyester acrylate, polyurethane acrylate, and epoxy acrylate.

Examples of radical polymerization inhibitors include (alkyl)phenols, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-tert-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutyl cresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, and cyclohexanone oxime.

(Ink composition)
Next, the use of the ink composition, which is one embodiment of the active energy ray-curable resin composition of the present invention, will be described. Hereinafter, the ink composition will also be referred to as an active energy ray-curable ink.
The active energy ray-curable ink of the present invention is prepared to have a composition consisting of 0 to 30% by weight of pigment, 5 to 40% by weight of binder resin, 20 to 70% by weight of the above-mentioned monomer having a radically polymerizable double bond, 0.01 to 1% by weight of the above-mentioned radical polymerization inhibitor, 1 to 20% by weight of photopolymerization initiator and/or sensitizer, and 0 to 10 parts by weight of other additives, based on the total weight of the ink.
Here, the resin (A) used in the present invention corresponds to a binder resin.

Activin energy ray-curable ink compositions are cured, for example, by light, which is an active energy ray. Light-curing methods generally use light sources that emit ultraviolet light, such as metal halide lamps, high-pressure mercury lamps, or LEDs.

If the active energy ray-curable ink of the present invention is made transparent and does not contain a pigment as a colorant, it becomes an OP varnish, and if it contains the pigment shown below, it becomes a color printing ink.

Pigments can be inorganic or organic. Inorganic pigments include yellow lead, zinc yellow, iron blue, barium sulfate, cadmium red, titanium oxide, zinc white, red iron oxide, alumina white, calcium carbonate, ultramarine, carbon black, graphite, aluminum powder, and red iron oxide. Organic pigments include soluble azo pigments such as β-naphthol, β-oxynaphthoic acid, β-oxynaphthoic acid anilide, acetoacetic acid anilide, and pyrazolone, as well as insoluble azo pigments such as β-naphthol, β-oxynaphthoic acid anilide, acetoacetic acid anilide monoazo, acetoacetic acid anilide disazo, and pyrazolone. Various known and commonly used pigments can be used, including phthalocyanine pigments such as phthalocyanine pigments, copper phthalocyanine blue, halogenated (chlorinated or brominated) copper phthalocyanine blue, sulfonated copper phthalocyanine blue, and metal-free phthalocyanine, as well as polycyclic and heterocyclic pigments such as quinacridones, dioxazines, threnes (pyranthrone, anthanthrone, indanthrone, anthrapyrimidine, flavanthrone, thioindigo, anthraquinones, perinones, and perylenes), isoindolinones, metal complexes, and quinophthalones.

The active energy ray-curable ink of the present invention may further contain a binder resin other than resin (A) as needed.

The content of resin (A) used in the present invention is preferably 5 to 40 parts by weight, and more preferably 10 to 30 parts by weight, based on the total ink content. If it is less than 5 parts by weight, the effects of the present invention will not be fully achieved, and if it is more than 40 parts by weight, the viscosity of the ink will be too high and it will not be suitable for printing.

Binder resins other than resin (A) used in the present invention include diallyl orthophthalate resin, diallyl isophthalate resin, diallyl terephthalate resin, polyester resin, polyvinyl chloride, poly(meth)acrylic acid ester, epoxy resin, polyurethane resin, petroleum (based) resin, cellulose derivatives (e.g., ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, polyamide resin, polyvinyl acetal resin, synthetic rubber such as butadiene-acrylonitrile copolymer, etc. One or more of these resins can be used.

Photopolymerization initiators include photocleavage initiators and hydrogen abstraction initiators.

Photocleavable initiators include α-(dimethyl)aminoalkylphenone compounds and α-morpholinoalkylphenone compounds.

More specifically, examples of α-(dimethyl)aminoalkylphenone compounds include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 or 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, and examples of α-morpholinoalkylphenone compounds include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one. These compounds may be used alone or in combination of two or more.

Furthermore, hydrogen abstraction polymerization initiators include dialkylbenzophenone compounds and thioxanthone compounds.

More specifically, dialkylaminobenzophenone compounds include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone and 4,4'-bis-(diethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Dialkylaminobenzophenone compounds may be used alone or in combination of two or more types. Examples of thioxanthone compounds include 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-hydroxy-3-(3,4-dimethyl-9-oxo-9Hthioxanthone-2-yloxy-N,N,N-trimethyl-1-propanamine hydrochloride, and the like. These may be used alone or in combination of two or more types.

Sensitizers include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 2,3,4-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, methyl-o-benzoylbenzoate, [4-(methylphenylthio)phenyl]phenylmethanone, (4-benzoylbenzyl)trimethylammonium chloride, 2-hydroxy- Examples include 2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-styrylpropan-1-one polymer, diethoxyacetophenone, dibutoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzoin normal butyl ether. These may be used alone or in combination of two or more.

Furthermore, other additives can be used in the active energy ray-curable ink of the present invention as needed.

For example, the radical polymerization inhibitors mentioned above can be cited as an example of an additive that imparts storage stability to the ink. Furthermore, examples of additives that impart abrasion resistance, anti-blocking, smoothness, and scratch resistance include natural waxes such as carnauba wax, Japan wax, lanolin, montan wax, paraffin wax, and microcrystalline wax, as well as synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, and silicone compounds.

Additives such as ultraviolet absorbers, infrared absorbers, and antibacterial agents can also be added depending on the required performance.

The actinic energy ray-curable ink of the present invention can be produced by the same method as that used for conventional actinic energy ray-curable inks. For example, the ink composition components, such as the pigment, the resin composition of the present invention, a monomer having a radically polymerizable double bond, a polymerization inhibitor, a photopolymerization initiator and a sensitizer, and other additives, can be mixed at a temperature between room temperature and 100°C using a milling, mixing, and adjustment machine such as a kneader, three-roll mill, attritor, sand mill, or gate mixer.

Printing methods include lithographic printing (normal lithographic printing using dampening water and waterless lithographic printing not using dampening water), letterpress printing, intaglio printing, and stencil printing, with lithographic printing being preferred.

There are no particular restrictions on the substrate for the printed matter, and printing can be done on any material, including paper, plastic, stickers, labels, and metal, with printing on paper being preferred.

The present invention will be explained in more detail below using examples, but the following examples are not intended to limit the scope of the present invention in any way. Note that in the present invention, "parts" means "parts by weight" and "%" means "% by weight."

In the present invention, the weight-average molecular weight was measured using a gel permeation chromatography (HLC-8320) manufactured by Tosoh Corporation. A calibration curve was created using a standard polystyrene sample. The eluent was tetrahydrofuran, and three TSKgel Super HM-M columns (manufactured by Tosoh Corporation) were used. Measurements were performed at a flow rate of 0.6 ml/min, an injection volume of 10 μl, and a column temperature of 40°C. Furthermore, in the present invention, unless otherwise specified, "molecular weight" refers to the weight-average molecular weight. Furthermore, the hydroxyl value was determined by the conventional potassium hydroxide titration method.

(Synthesis Example 1)
A four-neck flask equipped with a stirrer, Dean-Stark tube, thermometer, and gas inlet tube was charged with 10 parts of glycerin, 20 parts of ethylene glycol, and 53 parts of phthalic anhydride as raw materials, and heated to 220°C with stirring. The reaction was continued while removing the condensed water produced as the reaction proceeded, and the reaction was terminated when the theoretical amount of dehydration was reached, yielding Polyester Resin 1 (molecular weight: 4200, hydroxyl value: 187 mgKOH/g).

(Synthesis Examples 2 to 25)
Resins 2 to 25 were obtained in the same manner as in Synthesis Example 1, except that the raw materials were changed according to the compositions in Table 1.

The physical properties of the synthesized resin are also shown in Table 1.

(Production Example 1)
In a four-neck flask equipped with a stirrer, a cooler, a thermometer, and a gas inlet tube, 7 parts of toluene-2,4-diisocyanate, which is an isocyanate compound (a2), 35 parts of dipentaerythritol pentaacrylate, which is a hydroxyl group-containing acrylic compound (a3), 17.8 parts of dipentaerythritol hexaacrylate, which is a polyfunctional acrylic compound (B), 20 parts of ditrimethylolpropane tetraacrylate, and 0.2 parts of tertiary butylhydroquinone as a polymerization inhibitor were placed and reacted for 5 hours at 100 ° C. with stirring. Next, 20 parts of Resin 1, which is a polyester resin (a1), were placed and further reacted for 5 hours at 110 ° C. to obtain Resin Composition 1.

(Production Examples 2 to 30)
Resin compositions 2 to 30 were obtained in the same manner as in Production Example 1, except that the raw materials were changed according to the formulations in Table 2.

(Production Example 31)
In a four-neck flask equipped with a stirrer, a cooler, a thermometer, and a gas inlet tube, 25 parts of Resin 2, which is a polyester resin (a1), 53.4 parts of dipentaerythritol hexaacrylate and 20 parts of ditrimethylolpropane tetraacrylate, which are polyfunctional acrylic compounds (B), and 0.2 parts of tertiary butylhydroquinone as a polymerization inhibitor, were placed and dissolved with stirring at 100° C. for 1 hour. Next, 1.4 parts of toluene-2,4-diisocyanate, which is an isocyanate compound (a2), was placed and reacted at 110° C. for 5 hours to obtain Resin Composition 31.

(Production Examples 32 and 33)
Resin compositions 32 and 33 were obtained in the same manner as in Production Example 31, except that the raw materials were changed according to the formulations in Table 2.

(Production Example 34)
Into a four-neck flask equipped with a stirrer, a cooler, a thermometer, and a gas inlet tube, 30 parts of resin 2, which is polyester resin (a1), 49.8 parts of dipentaerythritol hexaacrylate and 20 parts of ditrimethylolpropane tetraacrylate, which are polyfunctional acrylic compounds (B), and 0.2 parts of tertiary butylhydroquinone as a polymerization inhibitor, were placed, and the mixture was dissolved with stirring at 100°C for 1 hour to obtain resin composition 34.

(Examples 1 to 24, Comparative Examples 1 to 10)
Resin compositions 1 to 34 and initiators were mixed according to the formulations in Table 3 to obtain samples of Examples 1 to 24 and Comparative Examples 1 to 10. UV-cured films were prepared from the obtained samples and evaluated by an MEK (methyl ethyl ketone) rubbing test. The results are also shown in Table 3.

<MEK rubbing test>
For MEK rubbing, a sample for MEK rubbing was applied to a corona-treated PET substrate (A-PET sheet Novaclear A2012, manufactured by Mitsubishi Chemical Corporation, thickness 0.25 mm) using an RI tester (simple color developer), and cured using a metal halide lamp (output: 96 W/cm, lamp distance: 10 cm, conveyor speed: 100 m/min, number of passes: 1). The UV-cured film was rubbed back and forth with a cotton swab soaked in MEK, and the degree of effectiveness was judged from the number of times the cotton swab was rubbed back and forth until the UV-cured film was damaged. ◎ and ○ indicate practical levels.
(Evaluation criteria) ⊚: 100 times or more, ○: 50 times or more but less than 100 times, △: 25 times or more but less than 50 times, ×: less than 25 times

Examples 1 to 24 demonstrate that the resin composition of the present invention is superior to MEK rubbing.

(Examples 25 to 48, Comparative Examples 11 to 20)
The actinic ray-curable inks of Examples 25 to 48 and Comparative Examples 11 to 20 were obtained by milling in a three-roll mill according to the compositions in Table 4. The "viscosity" and "fluidity" of the obtained actinic ray-curable ink compositions were measured, and the "dot gain" of the printed matter and "ink fountain run-off" on the printing press were investigated. The results are also shown in Table 4.

<Viscosity measurement method>
The viscosity was measured using a viscoelasticity measuring device (HAAKE RheoStress 6000) manufactured by ThermoFisher Scientific Co., Ltd., under conditions of a measurement temperature of 25°C and a cone plate (diameter: 20 mm, tilt angle: 0.5°).

<Method of measuring fluidity>
2.1 ml of ink was placed on a metal plate with a hemispherical depression, left to stand for 2 minutes, then tilted at a 60-degree angle and the length of ink flowing over 10 minutes was measured and evaluated based on the following evaluation criteria. A higher value indicates less ink clumping and better fluidity. ◎ and ○ are practical levels.
(Evaluation criteria) ⊚: 100 mm or more, ○: less than 100 mm to 75 mm or more, △: less than 75 mm to 50 mm or more, ×: less than 50 mm

<Method for evaluating dot gain in printed matter>
Printing was carried out at a speed of 10,000 sheets per hour using an actual offset sheet-fed printing press, LITHRONE L426 (Komori Corporation), and the extent to which 50% dots on the plate surface expanded in the printed matter after 5,000 sheets had been printed (dot gain) was measured using a SpectroEye manufactured by GretagMacbeth. ○ indicates a practical level.
(Evaluation criteria) ◯: Dot gain 10% or more, △: Dot gain less than 10% 8% or more, ×: Dot gain less than 8%

<Ink fountain run-off evaluation method>
Printing was carried out under the above printing conditions, and the occurrence of "ink fountain run-out," a problem in which ink is not scraped off by the ink supply roller in the ink fountain during printing, was observed. ◎ and ○ are at practical levels.
(Evaluation criteria) ⊚: No occurrence for 20 minutes or more, ○: No occurrence for 10 minutes or more but less than 20 minutes, △: No occurrence for 5 minutes or more but less than 10 minutes, ×: Occurs in less than 5 minutes

<Method for evaluating curability>
Curability was evaluated by applying 1 g/ ^m² of ink to PE-coated paper using an RI tester (simple color developer), curing the ink using a metal halide lamp (manufactured by Eye Graphics Co., Ltd., output: 96 W/cm, lamp distance: 10 cm) at various conveyor speeds (80, 100, 120 m/min), and rubbing the ink with a cotton cloth to evaluate the surface condition of the ink coating. ◎ and ○ indicate practical levels.
(Evaluation criteria) ⊚: no scratches at all, ○: some scratches, △: scratches, ×: no coating film

The inks of Examples 25 to 48 of the present invention have better curing properties and flowability than the inks of Comparative Examples 11 to 20, and it was found that active energy ray-curable inks can be obtained that can eliminate problems during printing.

The resin composition of the present invention can enhance the curing reactivity of the resin composition to active energy rays by reacting a large number of acrylic compounds with a hydroxyl group-containing polyester resin, and after curing, it is possible to form a film with a highly crosslinked structure. Therefore, in addition to the offset sheet-fed printing specifically described, it is also useful for various printing inks, paints, coating agents, photoresists, etc.

Claims (5)

Resin (A) obtained by reacting a hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3), and polyfunctional acrylic compound (B).
An active energy ray-curable resin composition comprising:
the hydroxyl group-containing polyester resin (a1) is a resin obtained by reacting a polyhydric alcohol containing a trihydric or higher alcohol with a polybasic acid under conditions in which the OH/COOH molar ratio is 1.10 to 2.20 and the amount of the trihydric or higher alcohol relative to the total amount of the polyhydric alcohol is 13 mol% or more;
the hydroxyl value of the hydroxyl-containing polyester resin (a1) is 50 or more,
The weight average molecular weight of the hydroxyl group-containing polyester resin (a1) is 3,000 or more,
An active energy ray-curable resin composition, characterized in that the hydroxyl group-containing acrylic compound (a3) contains dipentaerythritol pentaacrylate or pentaerythritol triacrylate . The active energy ray-curable resin composition according to claim 1, wherein the isocyanate compound (a2) is a diisocyanate compound. The active energy ray-curable resin composition according to claim 1 or 2, which is an ink composition. A method for producing the active energy ray-curable resin composition according to any one of claims 1 to 3, comprising the step of reacting a hydroxyl group-containing polyester resin (a1), an isocyanate compound (a2), and a hydroxyl group-containing acrylic compound (a3) in a polyfunctional acrylic compound (B) to obtain resin (A). A printed material obtained by printing the active energy ray-curable resin composition according to any one of claims 1 to 3 onto a substrate.