JP2002285062A - Activated energy ray curable printing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activated energy ray curable printing ink composition having good adhesive properties to plastics, particularly polypropylene. SOLUTION: The activated energy ray curable printing ink composition comprises a urethane (meth) acrylate resin [A] obtained by reacting a diisocyanate trimer (a1) with a hydroxy group containing (meth) acrylate (a2), and a cycloaliphatic (meth) acrylate [B].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy ray-curable printing ink composition, and more particularly to an ink composition having excellent curability and excellent adhesion to polyolefin.
The present invention relates to a printing ink composition having an active energy ray-curable urethane (meth) acrylate-based resin as a main component. In the present specification, (meth) acrylate means acrylate and / or methacrylate, (meth) acrylic acid means acrylic acid and / or methacrylic acid, and (meth) acryloyl means acryloyl And / or methacryloyl.

[0002]

2. Description of the Related Art Conventionally, printing inks which are hardened by active energy rays such as ultraviolet rays are superior in terms of hygiene and environment to solvent type inks, and have a very short energy consumption. Since curing is completed by irradiation of the line,
Widely used for printing on various substrates. In particular, as disclosed in JP-A-6-184484, for example, a printing ink composition containing a urethane (meth) acrylate resin as a main component balances the flexibility of a cured film with the adhesiveness to a substrate. It is known that post-processing properties such as printability can be excellent.

[0003]

However, in the above-mentioned publication, although the adhesive strength to a polar plastic material is moderate, the adhesive strength to a non-polar plastic material such as polyolefin, metal or glass is not sufficient. In terms of printability on polyolefin molded articles whose use in the market is expanding, there are limitations in market development, and improvements are desired.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above circumstances, and as a result, have found that diisocyanate 3
Monomer (a1) and a hydroxyl group-containing (meth) acrylate (a
It has been found that an active energy ray-curable printing ink composition containing a urethane (meth) acrylate-based resin [A] and an alicyclic (meth) acrylate [B] obtained by reacting with 2) meets the above object. Thus, the present invention has been completed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Urethane (meth) acrylate resin [A] The urethane (meth) acrylate resin [A] used in the present invention is obtained by reacting a diisocyanate trimer (a1) with a hydroxyl group-containing (meth) acrylate (a2). Manufactured.

Diisocyanate trimer (a1) The diisocyanate constituting the diisocyanate trimer (a1) is not particularly limited as long as it is a compound having two isocyanate groups in the molecule. Alicyclic, aromatic and aliphatic diisocyanates are used. Specifically, isophorone diisocyanate,
Alicyclic diisocyanates such as norbornene diisocyanate and 1,3-bis (isocyanatomethyl) cyclohexane; tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, Aromatic diisocyanates such as tetramethylxylylene diisocyanate; and aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, among which isophorone diisocyanate is preferably used.

The hydroxyl group-containing (meth) acrylate (a2) The hydroxyl group-containing (meth) acrylate (a2) is not particularly limited as long as it is a (meth) acrylate compound having one or more hydroxyl groups in a molecule. For example, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxyethyl Acryloyl phosphate, 4-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-
Hydroxypropyl phthalate, glycerin di (meth)
Acrylate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate, caprolactone modified 2
-Hydroxyethyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate and the like. Among them, pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate are practical.

In producing the urethane (meth) acrylate resin [A] used in the present invention, a plurality of active hydrogens may be contained, if necessary, in addition to the essential components (a1) and (a2). Compounds, such as polyols, may be reacted. Specifically, ethylene glycol, diethylene glycol, triethylene glycol,
Tetraethylene glycol, polyethylene glycol,
Propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, 1,3-
Butanediol, 1,4-butanediol, polybutylene glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, cyclohexanedimethanol, hydrogenated bisphenol A, polycaprolactone diol, trimethylolethane, polytrimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, polypentaerythritol, sorbitol, mannitol, arabitol,
Polyhydric alcohols such as xylitol, galactitol, glycerin, polyglycerin, and polytetramethylene glycol; polyether polyols such as polyethylene oxide, polypropylene oxide, and ethylene oxide / propylene oxide block copolymers or random copolymers; Polyhydric alcohol or polyether polyol and maleic anhydride, maleic acid, fumaric acid,
Polyester polyols which are condensates with polybasic acids such as itaconic anhydride, itaconic acid, adipic acid and isophthalic acid; caprolactone-modified polyols such as caprolactone-modified polytetramethylene polyol; polybutadiene such as polyolefin-based polyols and hydrogenated polybutadiene polyol Polyols such as a system polyol are exemplified.

Urethane (meth) acrylate resin
The method for producing [A] is not particularly limited, and the trimer (a1) of diisocyanate and (meth) acrylate (a2) containing a hydroxyl group are usually reacted at a temperature of about 50 to 90 ° C. Until the residual isocyanate groups become 0 to 0.5% by weight,
It is advantageous to react. Diisocyanate trimer (a1) and hydroxyl group-containing (meth) acrylate (a2)
Means that when (a2) contains one hydroxyl group, (a1):
The reaction is preferably performed at a ratio such that (a2) has a reaction molar ratio of 1: 3.0 to 1: 3.2. During the reaction,
For the purpose of accelerating the reaction, it is also preferable to use a catalyst such as dibutyltin dilaurate, an inert solvent such as ethyl acetate, butyl acetate, and toluene, and an antioxidant.

Thus, the urethane (meth) acrylate resin [A] is obtained. In the present invention, the weight average molecular weight of [A] is preferably from 2,000 to 30,000, and more preferably from 3,000 to 20,000. . If the weight average molecular weight is less than 2,000, the cured product (ink coating or the like) becomes brittle, and if it exceeds 30,000, the curability deteriorates, which is not preferable.

The above weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and is determined by high performance liquid chromatography (Showa Denko;
xGPC system-11 type ”), column: Sh
Odex GPC KF-806L (exclusion limit molecular weight:
2 × 10 ^7, separation range: 100 to 2 × 10 ^7, theoretical plate number: 10,000 plates / the filler material: styrene - divinylbenzene copolymer, filler particle size: using three series of 10 [mu] m) It is measured by

The glass transition temperature (measured by TMA (thermomechanical analysis) method) of the urethane (meth) acrylate resin [A] is preferably -40 to 80 ° C, more preferably 0 to 70 ° C. . If the temperature is lower than -40 ° C, the curability is poor. If the temperature is higher than 80 ° C, the cured product (ink coating film or the like) becomes brittle, which is not preferable.

Active energy ray-curable printing ink composition
The active energy ray-curable printing ink composition of the present invention needs to contain an alicyclic (meth) acrylate [B] together with the urethane (meth) acrylate resin [A]. The combination of [B] is important in that it can be diluted without impairing the adhesion. Specific examples of the alicyclic (meth) acrylate [B] include dicyclopentenyl (meth).
Acrylate, tricyclodecanyl (meth) acrylate, cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclononyl (meth) acrylate, cyclodecyl (meth)
Acrylate, cyclododecyl (meth) acrylate,
Examples include cyclostearyl (meth) acrylate, cyclolauryl (meth) acrylate, and isobornyl (meth) acrylate. Among them, dicyclopentenyl (meth) acrylate and tricyclodecanyl (meth) acrylate are preferably used.

In the printing ink composition of the present invention, other than the above-mentioned component (B), other ethylenically unsaturated compounds may be used in combination, if necessary. Representative of other ethylenically unsaturated compounds are Michael adduct of (meth) acrylic acid and 2- (meth) acryloyloxyalkyldicarboxylic acid monoester. Examples of the Michael adduct of (meth) acrylic acid include acrylic acid dimer [formula (1) below], methacrylic acid dimer, acrylic acid trimer [formula (2)], methacrylic acid trimer, acrylic acid tetramer [(( 3) Formula], methacrylic acid tetramer and the like, and these can be used in a mixture. Among them, an acrylic acid dimer represented by the following formula (1) is preferable.

[0015]

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As the 2- (meth) acryloyloxyalkyldicarboxylic acid monoester, 2- (meth) acryloyloxyethyldicarboxylic acid monoester is preferable. For example, 2-acryloyloxyethylsuccinic acid monoester [formula (4) below] 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester [formula (5) below],
Methacryloyloxyethyl phthalate monoester, 2
-Acryloyloxyethyl hexahydrophthalic acid monoester [formula (6) below], 2-methacryloyloxyethyl hexahydrophthalic acid monoester, and the like. Above all, 2-acryloyloxyethyl hexahydrophthalic acid monoester represented by the following formula (6) is preferable. Further, in addition to the Michael adduct of (meth) acrylic acid and 2- (meth) acryloyloxyalkyldicarboxylic acid monoester, ω-carboxy-polycaprolactone monoacrylate [formula (7) below] and the like are also included.

[0017]

Embedded image

As other ethylenically unsaturated compounds, other (meth) acrylates other than those described above may be used in combination. For example, monofunctional (meth) acrylates,
There are functional (meth) acrylates and trifunctional or higher (meth) acrylates. Examples of such monofunctional (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-stearyl (meth) acrylate, and phenoxyethyl (meth) acrylate. A) acrylate, glycerin mono (meth) acrylate, glycidyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, phenol ethylene oxide modified (n = 2) (meth) acrylate, nonylphenol propylene oxide modified (n =
2.5) (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, furfuryl (meth) acrylate, carbitol (meth) acrylate, benzyl (meth) acrylate, butoxyethyl (meth) acrylate, allyl (meth) Acrylate,
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) ) Acrylate, 3
-Chloro-2-hydroxypropyl (meth) acrylate and the like.

As the bifunctional (meth) acrylate, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di ( (Meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth)
Acrylate, ethylene oxide modified bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, 1,6
-Hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, diglycidyl phthalate Di (meth) acrylate,
Hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate;

Examples of the trifunctional or higher functional (meth) acrylate include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Examples thereof include dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, and glycerin polyglycidyl ether poly (meth) acrylate. Also, isocyanuric acid derivatives such as isocyanuric acid ethylene oxide-modified tri (meth) acrylate and isocyanuric acid ethylene oxide-modified di (meth) acrylate can be used.

Further, examples of the ethylenically unsaturated compound other than (meth) acrylate include styrene, vinyltoluene, chlorostyrene, α-methylstyrene, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, vinylcaprolactam and the like.

The amount of [A] and [B] in the printing ink composition of the present invention is such that [B] is 10 to 200 parts by weight, preferably 30 to 10 parts by weight per 100 parts by weight of [A].
0 parts by weight. If [B] is less than 10 parts by weight, the viscosity is so high that it is not suitable for printing, and if it exceeds 200 parts by weight, the adhesion to polyolefins is unfavorably deteriorated. When other monomers are used in combination, the blending ratio by weight to [B] is preferably 1 to 50% by weight, particularly preferably 5 to 30% by weight.

Curing by irradiation with active energy rays The printing ink composition of the present invention is cured by irradiation with active energy rays after printing. The energy rays include far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays and the like. In addition to electromagnetic waves such as light rays, X-rays, and γ-rays, electron beams, proton beams, neutron beams, etc. can be used, but curing by ultraviolet irradiation is advantageous from the viewpoints of curing speed, availability of irradiation equipment, and price. is there. As a method of ultraviolet curing, 150 to 45
Irradiation may be performed at about 100 to 3000 mJ / cm ² using a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, or the like that emits light in a wavelength range of 0 nm.

For curing by ultraviolet irradiation, it is preferable to use a photopolymerization initiator in combination, and the photopolymerization initiator is not particularly limited as long as it generates a radical by the action of light. Specifically, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-
(4-Isopropylenephenyl) -2-hydroxy-2
-Methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) -phenyl (2-
(Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholinopropane-
1, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
Benzoin isobutyl ether, benzyldimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'-dimethyl-4-methoxybenzophenone, Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone,
Camphorquinone, dibenzosuberone, 2-ethylanthraquinone, 4 ', 4 "-diethylisophthalophenone, 3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, α-acyloxime ester , Acylphosphine oxide, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, 4- (2-hydroxyethoxy) phenyl-
(2-hydroxy-2-propyl) ketone and the like. Among them, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropane -1-One is preferably used.

The amount of the photopolymerization initiator is as follows.
1 to 10 with respect to a total of 100 parts by weight of [A] and [B]
It is preferable that the amount is from 2 to 5 parts by weight. If the amount is less than 1 part by weight, the curing speed of ultraviolet curing is extremely slow, and if it exceeds 10 parts by weight, the curability is not improved and it is useless.

Further, triethanolamine, triisopropanolamine, 4,4
4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-
Dimethylaminoethyl benzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy) ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate,
It is also possible to use 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone or the like in combination.

In preparing a printing ink,
Inorganic coloring pigments, organic coloring pigments, organic matting pigments and the like are used alone or in combination. The compounding amount is suitably 100 to 200 parts by weight with respect to 100 parts by weight in total of [A] and [B]. Of course, thixotropic regulators, leveling agents, defoamers, pigment wetting agents, dispersants, thermal polymerization inhibitors, antioxidants, flame retardants, antistatic agents, fillers, stabilizers, reinforcing agents, matting agents, etc. It is also possible to mix well-known additives for printing inks. Other diluents can also be blended, such as ethyl acetate, toluene, xylene, methanol, ethanol, butanol,
Examples include acetone, methyl isobutyl ketone, methyl ethyl ketone, cellosolves, and diacetone alcohol.

The active energy ray irradiation type printing ink composition of the present invention can be used for non-polar substances such as polyolefin resins such as polyethylene and polypropylene and molded articles thereof (films, sheets, cups, containers, bags, etc.). And excellent adhesion (adhesion) performance. The printing method on the substrate is not particularly limited, and may be arbitrarily performed such as screen printing, offset printing, flexographic printing, and the like.

[0029]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, “%” and “part” refer to
Unless otherwise specified, it is based on weight. Various urethane (meth) acrylate-based resins [A] were produced in the following manner. Urethane acrylate resin [A-1] In a four-necked flask equipped with a thermometer, a stirrer, a water-cooled condenser, and an air inlet, 133.5 parts (0.18 mol) of a trimer of isophorone diisocyanate was charged. 80
Heated to ° C. to dissolve. Subsequently, after introducing air into the liquid, 249.3 parts (0.56 mol) of pentaerythritol triacrylate and 0.3% of methyl ethyl hydroquinone were added.
8 parts and 0.38 part of dibutyltin dilaurate were charged and reacted at the same temperature for 5 hours. When the remaining isocyanate groups became 0.3%, the reaction was completed. After the reaction,
688.9 parts of ethyl acetate was added to obtain a urethane acrylate resin [A-1] having a solid content of 35% [glass transition temperature: 68 ° C, weight average molecular weight: 4,500].

Urethane acrylate resin [A-2] Trimer of isophorone diisocyanate of A-1 133.
The same operation as in A-1 was performed, except that 100 parts (0.17 mol) of a trimer of hexamethylene diisocyanate was used instead of 5 parts (0.18 mol), to obtain a urethane acrylate resin [A-2]. ] [Glass transition temperature 70 ° C, weight average molecular weight 5700].

Urethane acrylate resin [A-3] pentaerythritol triacrylate 24 of A-1
The same operation as in A-1 was carried out except that 302.4 parts (0.56 mol) of dipentaerythritol pentaacrylate was used instead of 9.3 parts (0.56 mol), and the urethane acrylate resin [A -3] [Glass transition temperature 7
0 ° C, weight average molecular weight 6000].

Urethane acrylate resin [A-4] Trimer of isophorone diisocyanate of A-1 133.
A except that 166 parts (0.75 mol) of isophorone diisocyanate was used instead of 5 parts (0.18 mol)
-1, the same procedure as in Example 1 was repeated to obtain a urethane acrylate resin [A-4] [glass transition temperature: 65 ° C.
870].

[B] used the following various types. [B-1] Dicyclopentenyl acrylate [B-2] Tricyclodecanyl acrylate [B-3] Tripropylene glycol diacrylate

Examples 1 to 5 and Comparative Examples 1 to 4 The above [A] and [B] were mixed at the compounding amounts shown in Table 1, and further added to 100 parts of the total of [A] and [B]. 50 parts of titanium oxide, 1 part of a silicone-based defoamer, 2 parts of an acrylic leveling dispersant, and a photopolymerization initiator [Irgacure 18 manufactured by Ciba Specialty Chemicals Co., Ltd.
4 "] 3 parts were added to obtain a UV-curable white ink composition for printing. The following evaluation was performed about the obtained composition and the adhesiveness of the ink was confirmed. Table 2 shows the evaluation results.

(Cross-cut adhesion test) The obtained composition was placed on a polypropylene plate [size: 1.0 mm (thickness) x 70 m
mx 150 mm: manufactured by Nippon Test Panel Co.] A 10 µm thick coating was applied to the surface of the base material using a # 20 bar coater, and then a metal halide lamp 120 W1 placed at a height of 10 cm from the conveyor belt was condensed. By type, 1
After passing once at a line speed of 0 m / min and irradiating with ultraviolet rays (integrated light amount 240 mJ / cm ² ) to cure, a cross-cut adhesion test was performed according to JIS K5400, and the measurement result was a non-peeled cross-cut. The fraction is displayed by the number / the total number of grids. A larger fraction indicates better adhesion.

Examples 6 to 7 The same procedures as in Examples 1 to 5 were carried out except that carbon iron oxide was used in place of the titanium oxide, and that [A] and [B] were used in the amounts shown in Table 1. An ultraviolet curable black ink composition for printing was obtained according to the procedure. Table 2 shows the evaluation results.

[Table 1] [A] [B] Type Content Type Content (parts by weight in terms of solid content ) (parts by weight in terms of solid content ) Example 1 A-1 100 B-150 (white ink) A-2 100 B-1 100 (white ink) ３ 3 A-3 100 B-150 (white ink) ４ 4 A-1 100 B-250 (white ink) ５ 5 A-2 100 B-2 100 (White ink) 〃 6 A-1 100 B- 140 (black ink) ７ 7 A-1 100 B-240 (black ink) Comparative Example 1 A-1 100 B-350 (white ink) 〃 2 A -2 100 B-3 100 (white ink) 〃 3 A-3 100 B- 350 (white ink) ４ 4 A-4 100 B-150 (white ink)

[0038]

[0039]

The active energy ray-curable printing ink composition of the present invention has excellent curability and also has excellent adhesiveness (adhesion) to polyolefins, and its use in the market is expanding. It is extremely useful in the field of printing on polyolefin moldings, which are being developed.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yusuke Sugita 2-13-1, Muroyama, Ibaraki-shi, Osaka Inside the Central Research Laboratory of Nippon Gosei Chemical Industry Co., Ltd. No. 1 F-term in the Central Research Laboratory of Nippon Kasei Chemical Co., Ltd. 4J039 AD10 AE04 BE27 EA05 EA06 EA36 FA02

Claims (5)

[Claims] 1. A urethane (meth) acrylate resin [A] and an alicyclic (meth) acrylate [B] obtained by reacting a diisocyanate trimer (a1) with a hydroxyl group-containing (meth) acrylate (a2). An active energy ray-curable printing ink composition comprising: 2. The active energy ray-curable printing ink composition according to claim 1, wherein the alicyclic (meth) acrylate [B] is dicyclopentenyl (meth) acrylate or tricyclodecanyl (meth) acrylate. 3. The active energy ray-curable printing ink composition according to claim 1, wherein the trimer of diisocyanate (a1) is a trimer of isophorone diisocyanate. 4. A hydroxyl group-containing (meth) acrylate (a)
The active energy ray-curable printing ink composition according to any one of claims 1 to 3, wherein 2) is pentaerythritol tri (meth) acrylate or dipentaerythritol penta (meth) acrylate. 5. The active energy ray-curable printing ink composition according to claim 1, which is used for printing for a polyolefin substrate.