Photocurable adhesive composition for printing, cured product, and laminate

Abstract

To provide a photocurable adhesive composition for printing excellent in repeated printability, photocurability under presence of oxygen, and adhesiveness and retention performance after cure, and a cured product and a laminate obtained using the photocurable adhesive composition for printing.SOLUTION: A photocurable adhesive composition for printing contains a (meth)acryl monomer, a photopolymerization initiator and a thermoplastic resin, and does not contain a moisture-curable resin, where the photopolymerization initiator has a weight average molecular weight of 800 or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photocurable pressure-sensitive adhesive composition for printing. The present invention also relates to a cured product and a laminate obtained by using the photocurable pressure-sensitive adhesive composition for printing. [Background technology]

[0002] Adhesives are used to bond electronic components inside electronic devices such as smartphones and PCs. In a typical method of bonding using adhesives, first, an adhesive sheet is prepared with separators arranged on both sides of the adhesive, and then the adhesive sheet is cut into a desired shape. Then, one separator is peeled off from the cut adhesive sheet, and one side of the exposed adhesive is bonded to a first adherend, and then the other separator is peeled off, and the other side of the exposed adhesive is bonded to a second adherend. In this method, a part of the adhesive sheet is discarded after cutting, resulting in waste. In response to this, a method has been considered in which a pressure-sensitive adhesive composition is printed in a desired shape and then attached to an adherend without producing a pressure-sensitive adhesive sheet, which can reduce the generation of waste.

[0003] For example, Patent Document 1 discloses an invention for providing a radiation-curable pressure-sensitive adhesive composition that allows fine patterning and exhibits high adhesion to various adherends such as metals, plastics, etc. Patent Document 1 describes a radiation-curable pressure-sensitive adhesive composition that contains 10 to 70% by weight of an aromatic ring-free ethylenically unsaturated monomer, 1 to 10% by weight of a photopolymerization initiator, and 10 to 55% by weight of a crosslinking agent.

[0004] Patent Document 2 discloses an invention for providing a photocurable adhesive composition that, even when irradiated with light in the presence of oxygen, gives a laminate having adhesive strength equivalent to that in the absence of oxygen. Patent Document 2 describes a photocurable adhesive composition that contains (A) a (meth)acrylate oligomer, (B) a monofunctional (meth)acrylic monomer, (C) a difunctional to tetrafunctional (meth)acrylic monomer, (D) a photoinitiator, (E) a tackifier having a softening point of 70 to 150°C, and (F) a liquid plasticizer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-216742 A [Patent Document 2] International Publication No. 2016 / 163152 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the method of printing the adhesive composition in a desired shape and then laminating it to the adherend without preparing an adhesive sheet can suppress the generation of waste. As a method of curing the adhesive composition, photocuring is preferable to avoid heating the adherend, but the conventional adhesive composition has problems such as needing replacement after each use and being inferior in repeated printability, difficulty in sufficiently curing when irradiated with light in the presence of oxygen, and insufficient adhesion and retention performance (creep resistance) after curing.

[0007] The present invention aims to provide a photocurable pressure-sensitive adhesive composition for printing that is excellent in repeated printability, photocurability in the presence of oxygen, and adhesiveness and retention performance after curing. Another object of the present invention is to provide a cured product and a laminate obtained by using the photocurable pressure-sensitive adhesive composition for printing. [Means for solving the problem]

[0008] The present disclosure 1 relates to a photocurable pressure-sensitive adhesive composition for printing, which contains a (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin, but does not contain a moisture-curable resin, and the photopolymerization initiator has a weight-average molecular weight of 800 or more. Disclosure 2 relates to a method for producing a photocurable pressure-sensitive adhesive composition for printing, comprising: a (meth)acrylic monomer; a photopolymerization initiator; and a thermoplastic resin; and no moisture-curable resin; the photocurable pressure-sensitive adhesive composition for printing is applied to a substrate to a thickness of 40 μm or more and 60 μm or less; and the applied surface is not sealed, and the applied surface is exposed to light at a wavelength of 365 nm and an illuminance of 500 mW / cm in an atmospheric environment. 2 of light, with an irradiation dose of 3000mJ / cm 2 The photocurable pressure-sensitive adhesive composition for printing is obtained by irradiating the photosensitive layer so as to satisfy the above conditions, thereby obtaining a cured product having a solids content of 90% or more and a gel content of 25% by mass or more and 60% by mass or less. The present disclosure 3 relates to the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 2, wherein the photopolymerization initiator has a weight-average molecular weight of 800 or more. The present disclosure 4 relates to the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1 or 2, wherein the photopolymerization initiator is a Norrish I type photopolymerization initiator having a weight average molecular weight of 800 or more. Disclosure 5 relates to the photocurable pressure-sensitive adhesive composition for printing according to Disclosure 4, in which the photopolymerization initiator has two or more carbonyl groups in one molecule that contribute to a Norrish type I cleavage reaction. The present disclosure 6 is the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, or 5, wherein the thermoplastic resin has a weight average molecular weight of 100,000 or more and 1,000,000 or less. The present disclosure 7 is the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, 5, or 6, wherein the thermoplastic resin is a block copolymer. The present disclosure 8 relates to the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 7, wherein the thermoplastic resin is a (meth)acrylic / styrene block copolymer. Disclosure 9 is the photocurable pressure-sensitive adhesive composition for printing according to Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, further comprising a nitrogen-containing vinyl compound, wherein the content of the nitrogen-containing vinyl compound in 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing is 0.1 parts by mass or more and 5.0 parts by mass or less. The present disclosure 10 is the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, further comprising an antifoaming agent. The present disclosure 11 is the photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, further comprising a leveling agent. The present disclosure 12 is a photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, which does not contain a solvent or contains 1 part by mass or less of a solvent per 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing. The present disclosure 13 is a photocurable pressure-sensitive adhesive composition for printing according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, which is used for screen printing and has a viscosity of 1 Pa s or more and 400 Pa s or less, as measured using an E-type viscometer at 25°C and 10 rpm. Disclosure 14 is a photocurable pressure-sensitive adhesive composition for printing according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, which is used for inkjet printing and has a viscosity of 0.001 Pa s or more and 10 Pa s or less, as measured using an E-type viscometer at 25°C and 10 rpm. The present disclosure 15 is a cured product obtained by curing the photocurable pressure-sensitive adhesive composition for printing of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14. The present disclosure 16 is a cured product of the present disclosure 15, having a solid fraction of 90% or more and a gel fraction of 25% by mass or more and 60% by mass or less. Disclosure 17 is a laminate having a release-treated film on at least one side of the cured product of Disclosure 15 or 16. The present invention will be described in detail below. Hereinafter, the photocurable pressure-sensitive adhesive composition for printing of Disclosure 1 will also be referred to as the "photocurable pressure-sensitive adhesive composition for printing of Invention 1," and the photocurable pressure-sensitive adhesive composition for printing of Disclosure 2 will also be referred to as the "photocurable pressure-sensitive adhesive composition for printing of Invention 2." Furthermore, matters common to the photocurable pressure-sensitive adhesive composition for printing of Invention 1 and the photocurable pressure-sensitive adhesive composition for printing of Invention 2 will be described as the "photocurable pressure-sensitive adhesive composition for printing of the present invention."

[0009] The present inventors have investigated the use of a photopolymerization initiator having a weight average molecular weight of a specific value or more for a photocurable adhesive composition for printing that contains a (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin, but does not contain a moisture-curable resin. As a result, they have found that a photocurable adhesive composition for printing that is excellent in repeated printability, photocurability in the presence of oxygen, and adhesiveness and retention performance after curing can be obtained, and have completed the present invention 1. The present inventors also investigated a printing photocurable pressure-sensitive adhesive composition that contains a (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin, but does not contain a moisture-curable resin, and that is photocured in the presence of oxygen to obtain a cured product with a solid content of 90% or more and a gel content of 25% by mass or more and 60% by mass or less. As a result, they found that a printing photocurable pressure-sensitive adhesive composition that is excellent in repeated printability, photocurability in the presence of oxygen, and adhesiveness and retention performance after curing can be obtained, and thus completed the present invention 2.

[0010] The photocurable pressure-sensitive adhesive composition for printing of the present invention contains a (meth)acrylic monomer. In particular, the photocurable pressure-sensitive adhesive composition for printing of the present invention preferably contains a monofunctional (meth)acrylic monomer and a polyfunctional (meth)acrylic monomer. In this specification, the term "(meth)acrylic" means acrylic or methacrylic, the term "(meth)acrylic monomer" means a monomer having a (meth)acryloyl group, and the term "(meth)acryloyl" means acryloyl or methacryloyl. In addition, in this specification, the term "monofunctional (meth)acrylic monomer" means a monomer having one (meth)acryloyl group in one molecule, and the term "polyfunctional (meth)acrylic monomer" means a monomer having two or more (meth)acryloyl groups in one molecule.

[0011] The monofunctional (meth)acrylic monomer is a polymerizable monomer that is polymerized by a reaction with a photopolymerization initiator described below. By containing the monofunctional (meth)acrylic monomer, the photocurable pressure-sensitive adhesive composition for printing of the present invention has excellent adhesion to various substrates. Examples of the monofunctional (meth)acrylic monomer include a monofunctional (meth)acrylic acid ester compound, a monofunctional (meth)acrylamide compound, and a monofunctional (meth)acrylimide compound.

[0012] Examples of the monofunctional (meth)acrylic acid ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. ) acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-Octafluoropentyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, 2-(((butylamino)carbonyl)oxy)ethyl (meth)acrylate, (3-propyloxetan-3-yl)methyl (meth)acrylate, (3-butyloxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)ethyl (meth)acrylate, (3-ethyl oxetan-3-yl)propyl (meth)acrylate, (3-ethyloxetan-3-yl)butyl (meth)acrylate, (3-ethyloxetan-3-yl)pentyl (meth)acrylate, (3-ethyloxetan-3-yl)hexyl (meth)acrylate, γ-butyrolactone (meth)acrylate, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-cyclohexyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal acrylate, etc., In this specification, the term "(meth)acrylate" means acrylate or methacrylate.

[0013] Examples of the monofunctional (meth)acrylamide compound include N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-hydroxyethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide.

[0014] Examples of the monofunctional (meth)acrylimide compound include N-(meth)acryloyloxyethylhexahydrophthalimide.

[0015] The content of the monofunctional (meth)acrylic monomer in 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing of the present invention is preferably 45 parts by mass at the lower limit and 75 parts by mass at the upper limit. By making the content of the monofunctional (meth)acrylic monomer within this range, the obtained cured product has better adhesion to various substrates. The more preferred lower limit of the content of the monofunctional (meth)acrylic monomer is 50 parts by mass, and the more preferred upper limit is 70 parts by mass.

[0016] The polyfunctional (meth)acrylic monomer is a polymerizable monomer that is polymerized by the reaction of a photopolymerization initiator described below, and the polyfunctional (meth)acrylic monomer serves as a crosslinking component. Examples of the polyfunctional (meth)acrylic monomer include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, and polyfunctional epoxy (meth)acrylates. In this specification, the above-mentioned "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have been reacted with (meth)acrylic acid.

[0017] The polyfunctional urethane (meth)acrylate can be obtained, for example, by reacting an isocyanate compound with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin compound.

[0018] Examples of the isocyanate compound that is a raw material for the polyfunctional urethane (meth)acrylate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0019] As the isocyanate compound serving as a raw material for the polyfunctional urethane (meth)acrylate, a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, tetraethylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0020] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylates, mono(meth)acrylates of dihydric alcohols, and mono(meth)acrylates or di(meth)acrylates of trihydric alcohols. Examples of the hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin.

[0021] Examples of the polyfunctional (meth)acrylic acid ester compound include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-Propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethylol dicyclopentadiene Di(meth)acrylate, ethylene oxide modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl(meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, polybutadiene diol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, trimethylol dimethacrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, ethylene oxide-added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate , pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0022] Examples of the polyfunctional epoxy(meth)acrylate include bisphenol A type epoxy(meth)acrylate, bisphenol F type epoxy(meth)acrylate, bisphenol E type epoxy(meth)acrylate, and caprolactone modified versions of these.

[0023] The content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is preferably 1 part by mass at the lower limit and 8 parts by mass at the upper limit. By setting the content of the polyfunctional (meth)acrylic monomer within this range, the obtained cured product has better adhesion and retention performance to various substrates. The more preferred lower limit of the content of the polyfunctional (meth)acrylic monomer is 2 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0024] The photocurable pressure-sensitive adhesive composition for printing of the present invention contains a photopolymerization initiator. In the photocurable pressure-sensitive adhesive composition for printing of invention 1, the photopolymerization initiator has a weight-average molecular weight of at least 800. In addition, in the photocurable pressure-sensitive adhesive composition for printing of invention 2, the photopolymerization initiator preferably has a weight-average molecular weight of at least 800. By using a photopolymerization initiator having a weight-average molecular weight of at least 800, it becomes easy to adjust the solid fraction and gel fraction of the cured product to the ranges described below in the photocurable pressure-sensitive adhesive composition for printing of the present invention, and as a result, the photocurable pressure-sensitive adhesive composition has excellent photocurability in the presence of oxygen, and excellent adhesion and retention performance after curing. In the photocurable pressure-sensitive adhesive composition for printing of the first invention, the lower limit of the weight-average molecular weight of the photopolymerization initiator is preferably 1000, more preferably 1100. In the photocurable pressure-sensitive adhesive composition for printing of the second invention, the lower limit of the weight-average molecular weight of the photopolymerization initiator is more preferably 1000, even more preferably 1100. From the viewpoint of reactivity and the like, the upper limit of the weight-average molecular weight of the photopolymerization initiator in the photocurable pressure-sensitive adhesive composition for printing of the present invention is not particularly limited. However, from the viewpoint of reduced solubility and ease of handling when the molecular weight is significantly large, the upper limit is preferably 10,000, and more preferably 5,000. In the present specification, the "weight average molecular weight" can be determined by, for example, measuring the molecular weight distribution in terms of polystyrene using gel permeation chromatography (GPC). Specifically, for example, it can be determined by measuring under the following conditions using gel permeation chromatography (Waters Corporation, "2690 Separations Module" or the like). Solvent: Tetrahydrofuran Sample flow rate: 1mL / min Detector: Differential refractive index RI Column: GPC KF-806L (Showa Denko) Column temperature (measurement temperature): 40℃ Injection volume: 20μL

[0025] In the photocurable adhesive composition for printing of the present invention, the photopolymerization initiator is preferably a Norrish I type photopolymerization initiator having a weight average molecular weight of 800 or more. By using the Norrish I type photopolymerization initiator having a weight average molecular weight of 800 or more, the photocurable adhesive composition for printing of the present invention can more easily adjust the solid content and gel content of the cured product to the range described below. In particular, the photopolymerization initiator preferably has two or more carbonyl groups in one molecule that contribute to the cleavage reaction of the Norrish I type.

[0026] Examples of the Norrish I type photopolymerization initiator having a weight average molecular weight of 800 or more include polymers of ethyl (2,4,6-trimethylbenzoyl)-phenyl phosphonate, polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate, and bis(benzophenone-2-carboxylic acid) polyethylene glycol ester.

[0027] Among the above-mentioned Norrish I type photopolymerization initiators having a weight average molecular weight of 800 or more, commercially available ones include, for example, Omnipol TP and Omnipol 910 (both manufactured by IGM Resins).

[0028] The preferred lower limit of the content of the photopolymerization initiator in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is 1 part by mass, and the preferred upper limit is 20 parts by mass. When the content of the photopolymerization initiator is within this range, the obtained photocurable adhesive composition for printing has better photocurability in the presence of oxygen, and better adhesiveness and retention performance after curing. The more preferred lower limit of the content of the photopolymerization initiator is 3 parts by mass, and the more preferred upper limit is 10 parts by mass.

[0029] The photocurable pressure-sensitive adhesive composition for printing of the present invention contains a thermoplastic resin. By containing the thermoplastic resin, the photocurable pressure-sensitive adhesive composition for printing of the present invention has excellent retention performance when cured.

[0030] The thermoplastic resin has a weight average molecular weight of preferably 100,000 at the lower limit and 1,000,000 at the upper limit. By having the weight average molecular weight of the thermoplastic resin in this range, the printing performance is excellent and the obtained cured product has better retention performance. The weight average molecular weight of the thermoplastic resin is more preferably 200,000 at the lower limit and 500,000 at the upper limit.

[0031] The thermoplastic resin is preferably a block copolymer. By using the thermoplastic resin that is a block copolymer, the obtained cured product has better retention performance. In particular, the thermoplastic resin preferably contains a triblock copolymer.

[0032] The lower limit of the content of the triblock copolymer in the thermoplastic resin is preferably 50% by mass. When the content of the triblock copolymer is 50% by mass or more, the obtained cured product has better retention performance. The lower limit of the content of the triblock copolymer is more preferably 70% by mass. The content of the triblock copolymer in the thermoplastic resin may be 100% by mass, that is, the thermoplastic resin may contain only the triblock copolymer.

[0033] The thermoplastic resin which is a block copolymer is preferably a (meth)acrylic / styrene block copolymer, and more preferably a (meth)acrylic / styrene triblock copolymer.

[0034] The preferred lower limit of the content of the styrene-derived structure in the (meth)acrylic / styrene block copolymer is 3% by mass. When the content of the styrene-derived structure is 3% by mass or more, the obtained cured product has better retention performance. The more preferred lower limit of the content of the styrene-derived structure is 4% by mass. From the viewpoints of compatibility of the composition and adhesion to an adherend, the upper limit of the content of the structure derived from styrene is preferably 40% by mass, and more preferably 30% by mass.

[0035] The preferred lower limit of the content of the thermoplastic resin in 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing of the present invention is 1 part by mass, and the preferred upper limit is 60 parts by mass. By having the content of the thermoplastic resin in this range, the obtained cured product has better retention performance. The more preferred lower limit of the content of the thermoplastic resin is 10 parts by mass, and the more preferred upper limit is 40 parts by mass.

[0036] The photocurable pressure-sensitive adhesive composition for printing of the present invention does not contain a moisture-curable resin. By not containing the moisture-curable resin, the photocurable pressure-sensitive adhesive composition for printing of the present invention does not need to be replaced after each use and has excellent repeat printability. In this specification, the above-mentioned "moisture-curable resin" refers to a curable resin whose curing reaction proceeds when triggered by moisture in the air, such as a moisture-curable urethane resin or a resin having a crosslinkable silyl group.

[0037] The photocurable pressure-sensitive adhesive composition for printing of the present invention preferably further contains a nitrogen-containing vinyl compound as a polymerizable monomer. By containing the nitrogen-containing vinyl compound, the photocurable pressure-sensitive adhesive composition for printing obtained has better photocurability in the presence of oxygen.

[0038] The nitrogen-containing vinyl compound preferably contains at least one selected from the group consisting of monofunctional radically polymerizable monomers having a lactam structure and maleimide derivatives, and more preferably contains a maleimide derivative. The reaction system of the monofunctional radical polymerizable monomer having the lactam structure and the maleimide derivative basically proceeds by a hydrogen abstraction reaction. Photoradical polymerization by hydrogen abstraction reaction is less susceptible to oxygen inhibition, and can therefore increase surface curability. In addition, photoradical polymerization by hydrogen abstraction reaction produces a branched polymer and also increases cohesive strength. Therefore, by containing the monofunctional radical polymerizable monomer having the lactam structure and the maleimide derivative, the photocurable pressure-sensitive adhesive composition for printing can produce a cured product that is less susceptible to bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength. In this specification, the above "maleimide derivative" means a compound having a maleimide group.

[0039] Among the maleimide derivatives, examples of monofunctional maleimides include N-cyclohexylmaleimide, N-laurylmaleimide, 4-hydroxyphenylmaleimide, N-(4-carboxycyclohexylmethyl)maleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-chlorophenyl)maleimide, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N- Examples of the monofunctional maleimide include butyl maleimide, N-benzyl maleimide, N-phenylmethyl maleimide, N-(2,4,6-tribromophenyl) maleimide, N-(3-(triethoxysilyl)propyl) maleimide, N-octadecenyl maleimide, N-dodecenyl maleimide, N-(2-methoxyphenyl) maleimide, N-(2,4,6-trichlorophenyl) maleimide, and N-(1-hydroxyphenyl) maleimide. Among them, it is preferable to select a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom from the viewpoint of increasing the reaction rate. In addition, a maleimide derivative that has a structure in which hydrogen is bonded to a heteroatom from the viewpoint of improving adhesive strength may be used. Specifically, the monofunctional maleimide is preferably at least one selected from the group consisting of N-cyclohexyl maleimide, 4-hydroxyphenyl maleimide, and N-(4-carboxycyclohexylmethyl) maleimide, and more preferably N-cyclohexyl maleimide. Among the maleimide derivatives, examples of polyfunctional maleimides include N,N'-methylene bismaleimide, N,N'-trimethylene bismaleimide, N,N'-dodecamethylene bismaleimide, N,N'-(4,4'-diphenylmethane) bismaleimide, 1,4-dimaleimidecyclohexane, isophorone bisurethane bis(N-ethylmaleimide), N,N'-p-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-m-toluylene bismaleimide, and N,N'-4,4'-biphenyl Examples of the maleimide derivatives include N,N'-4,4'-(3,3'-dimethyl-biphenylene) bismaleimide, N,N'-4,4'-(3,3'-dimethyldiphenylmethane) bismaleimide, N,N'-4,4'-(3,3'-diethyldiphenylmethane) bismaleimide, N,N'-4,4'-diphenylpropane bismaleimide, N,N'-4,4'-diphenylether bismaleimide, N,N'-3,3'-diphenylsulfone bismaleimide, and N,N'-4,4'-diphenylsulfone bismaleimide. From the viewpoint of increasing the reaction rate, the above monofunctional maleimide may be used in combination with these polyfunctional maleimides as the maleimide derivatives, but it is not preferable to use a large amount of polyfunctional maleimide in combination because the gel fraction increases.

[0040] The monofunctional radically polymerizable monomer having a lactam structure is preferably a compound represented by the following formula (1).

[0041] [ka]

[0042] In the formula (1), n ​​represents an integer of 2 to 6.

[0043] Examples of the compound represented by the above formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, etc. Among these, N-vinyl-ε-caprolactam is preferred.

[0044] The content of the nitrogen-containing vinyl compound in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is preferably 0.1 parts by mass at the lower limit and 5.0 parts by mass at the upper limit. By making the content of the nitrogen-containing vinyl compound within this range, the obtained cured product has better surface curability and adhesion to various substrates. The content of the nitrogen-containing vinyl compound is more preferably 0.5 parts by mass at the lower limit and 3.0 parts by mass at the upper limit.

[0045] From the viewpoint of improving printability, etc., it is preferable that the photocurable pressure-sensitive adhesive composition for printing of the present invention further contains an antifoaming agent. Examples of the defoaming agent include silicone-based defoaming agents, acrylic polymer-based defoaming agents, vinyl ether polymer-based defoaming agents, and olefin polymer-based defoaming agents.

[0046] The content of the defoaming agent in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is preferably 0.1 parts by mass at the lower limit and 3.0 parts by mass at the upper limit. By having the content of the defoaming agent in this range, the printability of the obtained photocurable adhesive composition for printing is more excellent. The content of the defoaming agent is more preferably 0.5 parts by mass at the lower limit and 2.0 parts by mass at the upper limit.

[0047] From the viewpoint of improving printability, etc., it is preferable that the photocurable pressure-sensitive adhesive composition for printing of the present invention further contains a leveling agent. Examples of the leveling agent include silicone-based leveling agents, acrylic-based leveling agents, and fluorine-based leveling agents.

[0048] The preferred lower limit of the content of the leveling agent in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is 0.05 parts by mass, and the preferred upper limit is 3.0 parts by mass. By having the content of the leveling agent in this range, the printability of the obtained photocurable adhesive composition for printing becomes more excellent. The more preferred lower limit of the content of the leveling agent is 0.1 parts by mass, and the more preferred upper limit is 2.0 parts by mass.

[0049] The photocurable pressure-sensitive adhesive composition for printing of the present invention may further contain a tackifier. Examples of the tackifier include rosin-based resins and terpene-based resins.

[0050] The rosin-based resin may, for example, be rosin diol. The rosin diol is not particularly limited as long as it is a rosin-modified diol having two rosin skeletons and two hydroxyl groups in the molecule. Diols having a rosin component in the molecule are called rosin polyols, and these include polyether types such as polypropylene glycol (PPG) in which the skeleton excluding the rosin component is polyether, and polyester types such as condensation polyester polyols, lactone polyester polyols, and polycarbonate diols. Examples of the rosin diol include rosin ester obtained by reacting rosin with a polyhydric alcohol, epoxy-modified rosin ester obtained by reacting rosin with an epoxy compound, and modified rosin having a hydroxyl group, such as polyether having a rosin skeleton, etc. These can be produced by conventionally known methods.

[0051] Examples of the rosin component include abietic acid, abietic acid derivatives such as dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, and neoabietic acid, pimaric acid type resin acids such as levopimaric acid, hydrogenated rosins obtained by hydrogenating these, and disproportionated rosins obtained by disproportionating these.

[0052] Among the above rosin-based resins, commercially available ones include, for example, Pine Crystal D-6011, Pine Crystal KE-615-3, Pine Crystal KR-614, Pine Crystal KE-100, Pine Crystal KE-311, Pine Crystal KE-359, Pine Crystal KE-604, Pine Crystal D-6250 (all manufactured by Arakawa Chemical Industries Co., Ltd.), and the like.

[0053] Examples of the terpene resin include terpene phenol resins. The terpene phenol resin is a copolymer of phenol and a terpene resin, which is an essential oil component obtained from natural products such as rosin and orange peel, and also includes partially hydrogenated terpene phenol resins in which at least a portion of the copolymer is hydrogenated, or fully hydrogenated terpene phenol resins in which the copolymer is completely hydrogenated. Here, the fully hydrogenated terpene phenolic resin is a terpene resin obtained by substantially completely hydrogenating a terpene phenolic resin, and the partially hydrogenated terpene phenolic resin is a terpene resin obtained by partially hydrogenating a terpene phenolic resin. The terpene phenolic resin has a double bond derived from a terpene and an aromatic ring double bond derived from a phenol. Therefore, the fully hydrogenated terpene phenolic resin means a resin in which both the terpene portion and the phenol portion are completely or almost hydrogenated, and the partially hydrogenated terpene phenolic resin means a resin in which the degree of hydrogenation of these portions is not complete but partial. The hydrogenation method and reaction form are not particularly limited. Among the above terpene phenol-based resins, examples of commercially available ones include YS Polystar NH (fully hydrogenated terpene phenol-based resin) manufactured by Yasuhara Chemical Co., Ltd.

[0054] The preferred lower limit of the content of the tackifier in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is 7 parts by mass, and the preferred upper limit is 40 parts by mass. By having the content of the tackifier in this range, the obtained cured product has better adhesion to various substrates. The more preferred lower limit of the content of the tackifier is 10 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0055] The photocurable pressure-sensitive adhesive composition for printing of the present invention may contain a filler from the viewpoint of improving printability by adjusting the viscosity. As the filler, an inorganic filler or an organic filler can be used. Examples of the inorganic filler include silica, talc, glass beads, asbestos, gypsum, diatomaceous earth, smectite, bentonite, montmorillonite, sericite, activated clay, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum nitride, silicon nitride, barium sulfate, and calcium silicate. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and (meth)acrylic polymer fine particles. Of these, silica is preferred, and fumed silica is more preferred.

[0056] The preferred lower limit of the filler content in 100 parts by mass of the photocurable adhesive composition for printing of the present invention is 0.3 parts by mass, and the preferred upper limit is 5.0 parts by mass. By having the filler content within this range, the obtained photocurable adhesive composition for printing can easily adjust the viscosity while maintaining excellent adhesion after curing. The more preferred lower limit of the filler content is 0.7 parts by mass, and the more preferred upper limit is 3.0 parts by mass.

[0057] The photocurable pressure-sensitive adhesive composition for printing of the present invention may further contain various known additives such as a plasticizer, a silane coupling agent, a sensitizer, a heat curing agent, a curing retarder, an antioxidant, a storage stabilizer, and a dispersant, within a range that does not impair the object of the present invention. In addition, from the viewpoint of preventing a decrease in photoreactivity, it is preferable that the photocurable pressure-sensitive adhesive composition for printing of the present invention does not contain a solvent or contains 1 part by mass or less of a solvent per 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing.

[0058] Examples of the method for preparing the photocurable pressure-sensitive adhesive composition for printing of the present invention include a method of mixing the (meth)acrylic monomer, the photopolymerization initiator, the thermoplastic resin, and additives added as necessary using a mixer. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.

[0059] The photocurable pressure-sensitive adhesive composition for printing of the second invention is prepared by coating the photocurable pressure-sensitive adhesive composition for printing on a substrate to a thickness of 40 μm or more and 60 μm or less, and then, without sealing the coated surface, applying the composition to a substrate at a wavelength of 365 nm and an illuminance of 500 mW / cm in an atmospheric environment. 2 of light, with an irradiation dose of 3000mJ / cm 2 The lower limit of the solid content of the cured product obtained by irradiating the photocurable pressure-sensitive adhesive composition for printing of the present invention 1 is 90%. The photocurable pressure-sensitive adhesive composition for printing of the present invention 1 is coated on a substrate to a thickness of 40 μm to 60 μm, and the coated surface is not sealed, and the coating surface is exposed to light at a wavelength of 365 nm and an illuminance of 500 mW / cm in an atmospheric environment. 2 of light, with an irradiation dose of 3000mJ / cm 2 The preferred lower limit of the solid content of the cured product obtained by irradiation so as to satisfy the above condition is 90%. As the substrate, a PET film (release PET film) with a release treatment on the surface is preferably used. The preparation conditions of the cured product are that the photocurable pressure-sensitive adhesive composition for printing is applied to the substrate, and then the coated surface is irradiated with light in the presence of oxygen without being covered with a separator or the like. Therefore, the solid content of the cured product reflects the photoreactivity in the presence of oxygen. Since the solid content of the cured product is 90% or more, it can be said that the photoreactivity in the presence of oxygen is sufficiently high, making it possible to apply a method in which the printable photocurable pressure-sensitive adhesive composition is printed in a desired shape and then bonded to an adherend. In the photocurable pressure-sensitive adhesive composition for printing of the present invention 2, the lower limit of the solid content of the cured product is preferably 92%, more preferably 94%, and in the photocurable pressure-sensitive adhesive composition for printing of the present invention 1, the lower limit of the solid content of the cured product is more preferably 92%, even more preferably 94%. In addition, the higher the solid content of the cured product, the more preferable it is, but the practical upper limit is 99%.

[0060] Specifically, the solid content of the cured product can be measured, for example, according to the following procedure. That is, the photocurable pressure-sensitive adhesive composition for printing is first coated onto a release PET film as a substrate to a thickness of 40 μm to 60 μm. Then, without sealing the coated surface, the composition is irradiated with light at a wavelength of 365 nm and an illuminance of 500 mW / cm under atmospheric conditions using a light irradiation device. 2 The light is irradiated at 3000mJ / cm 2 By simultaneously irradiating the photocurable pressure-sensitive adhesive composition for printing with the light so as to obtain a cured product, the photocurable pressure-sensitive adhesive composition for printing is cured. Approximately 0.3 g of the obtained cured product is placed on an aluminum pan, and a mixed solvent containing THF:acetone:ethanol in a mass ratio of 8:1:1 is gently added so that the cured sample does not scatter, and the sample is allowed to swell for about 2 hours. The sample is then dried at 110°C for 30 minutes, 170°C for 1 hour, and 190°C for 30 minutes. The mass of the aluminum pan and the dried sample after drying are then weighed, and the solid content of the cured product is calculated using the following formula. Solid content of cured product (%) = (total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) x 100

[0061] In the photocurable pressure-sensitive adhesive composition for printing of the present invention 2, the lower limit of the gel fraction of the cured product is 25% by mass, and the upper limit is 60% by mass. In the photocurable pressure-sensitive adhesive composition for printing of the present invention 1, the preferred lower limit of the gel fraction of the cured product is 25% by mass, and the preferred upper limit is 60% by mass. When the gel fraction of the cured product is within the above range, the photocurable pressure-sensitive adhesive composition for printing of the present invention has excellent adhesion and retention performance after curing. In the photocurable pressure-sensitive adhesive composition for printing of the present invention 2, the preferred lower limit of the gel fraction of the cured product is 30% by mass, the preferred upper limit is 50% by mass, and the more preferred upper limit is 45% by mass. In the photocurable pressure-sensitive adhesive composition for printing of the present invention 1, the more preferred lower limit of the gel fraction of the cured product is 30% by mass, the more preferred upper limit is 50% by mass, and the even more preferred upper limit is 45% by mass.

[0062] Specifically, the gel fraction of the cured product can be measured, for example, according to the following procedure. That is, first, 0.15 g of the cured product obtained in the same manner as in the measurement of the solid content rate above is weighed into a glass bottle, and then immersed in 30 g of tetrahydrofuran and shaken and immersed at 23° C. for 36 hours. Next, the cured product is removed through a 200 mesh filter and heated and dried at 110° C. for 1 hour. The mass of the cured product is then measured, and the gel fraction can be calculated by the following formula. Gel fraction of cured product (mass%) = (W2 / W1) x 100 W1: Mass of the cured product before immersion in tetrahydrofuran at 23°C W2: Mass of the cured product after immersion in tetrahydrofuran at 23°C, removal, and drying

[0063] The photocurable adhesive composition for printing of the present invention is used for printing. If an adhesive layer is formed by applying a desired pattern on an adherend (substrate) by printing, there is an advantage that the cutting process can be omitted compared to the case where an adhesive of a desired shape is obtained by cutting a sheet-like adhesive just before lamination. As a result, it is possible to suppress the generation of waste and reduce the environmental load. Examples of methods for printing the photocurable pressure-sensitive adhesive composition for printing of the present invention include gravure printing, flexographic printing, slot die coating, knife coating, inkjet printing, spray coating, spin coating, screen printing, stencil printing, reverse offset printing, etc. Among these, screen printing and inkjet printing are preferably used.

[0064] When the photocurable pressure-sensitive adhesive composition for printing of the present invention is used for screen printing, the viscosity of the photocurable pressure-sensitive adhesive composition for printing of the present invention, measured using an E-type viscometer at 25°C and 10 rpm, preferably has a lower limit of 1 Pa·s and a higher limit of 400 Pa·s. When the viscosity is in this range, the photocurable pressure-sensitive adhesive composition for printing of the present invention is more suitable for screen printing. When the photocurable pressure-sensitive adhesive composition for printing of the present invention is used for screen printing, a more preferred lower limit of the viscosity is 5 Pa·s and a more preferred upper limit is 100 Pa·s. Furthermore, when the photocurable pressure-sensitive adhesive composition for printing of the present invention is used for inkjet printing, the viscosity of the photocurable pressure-sensitive adhesive composition for printing of the present invention, measured using an E-type viscometer at 25°C and 10 rpm, preferably has a lower limit of 0.001 Pa·s and a higher limit of 10 Pa·s. When the viscosity is in this range, the photocurable pressure-sensitive adhesive composition for printing of the present invention is more suitable for inkjet printing. When the photocurable pressure-sensitive adhesive composition for printing of the present invention is used for inkjet printing, a more preferred lower limit of the viscosity is 0.005 Pa·s and a more preferred upper limit is 1 Pa·s. As the E-type viscometer, for example, VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) can be used.

[0065] The photocurable adhesive composition for printing of the present invention is cured by irradiation with light to form an adhesive layer, and the method of use may be to form an adhesive layer on a substrate (separator) to prepare an adhesive sheet that can be transferred to an adherend, or to form an adhesive layer directly on an adherend. In the method of forming an adhesive layer directly on an adherend, the number of times of lamination can be minimized and air bubbles can be prevented from entering the interface during lamination. On the other hand, in the method of forming an adhesive layer on a substrate (separator), the adhesive layer is placed on the adherend by transfer, which has the advantage of having fewer constraints on construction.

[0066] The present invention also includes a cured product obtained by curing the photocurable pressure-sensitive adhesive composition for printing of the present invention.

[0067] The cured product of the present invention preferably has the above-mentioned solid fraction of 90% or more and the above-mentioned gel fraction of 25% by mass or more and 60% by mass or less.

[0068] The present invention also includes a laminate having a release-treated film on at least one side of the cured product of the present invention. Effect of the Invention

[0069] According to the present invention, it is possible to provide a photocurable pressure-sensitive adhesive composition for printing that is excellent in repeated printability, photocurability in the presence of oxygen, and adhesiveness and retention performance after curing. Also, according to the present invention, it is possible to provide a cured product and a laminate using the photocurable pressure-sensitive adhesive composition for printing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0071] (Examples 1 to 10, Comparative Examples 1 to 2) According to the compounding ratios shown in Table 1, each material was mixed with a planetary mixer (Thinky Corporation, "Awatori Rentaro") to obtain each photocurable pressure-sensitive adhesive composition for printing of the Examples and Comparative Examples. Details of the materials listed in the table are as follows. (Monofunctional (meth)acrylic monomer) CBA: Ethyl carbitol acrylate (Osaka Organic Chemical Industry Co., Ltd., "Viscoat #190") MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) M-140: N-Acryloyloxyethylhexahydrophthalimide (manufactured by Toagosei Co., Ltd.) (Polyfunctional (meth)acrylic monomer) · UA-160TM: Polyether-based multifunctional urethane acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) (Nitrogen-containing vinyl compounds) CHMI: N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd.) (Photopolymerization initiator) Omnipol TP: Polymer of ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate (manufactured by IGM Resins, a Norrish I type photopolymerization initiator with a weight average molecular weight of 1200) Omnipol 910: Polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate (manufactured by IGM Resins, a Norrish I type photoinitiator with a weight average molecular weight of 1100) Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins, a Norrish I type photoinitiator with a weight average molecular weight of 348) Omnirad 379: 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (IGM Resins, a Norrish type I photoinitiator with a weight average molecular weight of 380) (thermoplastic resin) Acrylic random copolymer A: The polymer obtained in the "Synthesis of acrylic random copolymer A" described below (weight average molecular weight: 300,000) Acrylic random copolymer B: The polymer obtained in "Synthesis of acrylic random copolymer B" described below (weight average molecular weight: 80,000) SCT-9001: Acrylic / styrene triblock copolymer (Fujikura Chemical Industries, weight average molecular weight 350,000) (tackifier) KE-359: Rosin ester (Arakawa Chemical Industries, Ltd.) (Filler) R805: Fumed silica (manufactured by Nippon Aerosil Co., Ltd.) (Antifoaming agent) ·KS-66: Silicone-based defoamer (manufactured by Shin-Etsu Chemical Co., Ltd.) (Leveling agent) BYK-302: Silicone leveling agent (manufactured by BYK Japan)

[0072] (Synthesis of Acrylic Random Copolymer A) In a 2L separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube, 75 parts by mass of butyl acrylate, 25 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of acrylic acid, and 300 parts by mass of ethyl acetate as a polymerization solvent were added. Next, nitrogen gas was blown in for 30 minutes to replace the atmosphere in the reaction vessel with nitrogen, and the reaction vessel was heated to 80°C while stirring. After 30 minutes, a polymerization initiator solution obtained by diluting 0.2 parts by mass of t-butylperoxy-2-ethylhexanoate with 5 parts by mass of ethyl acetate as a polymerization initiator was added dropwise to the reaction vessel over 2 hours. After that, the mixture was further reacted at 80°C for 6 hours, and then the reaction liquid was cooled to obtain an acrylic polymer solution. The obtained acrylic polymer solution was diluted with ethyl acetate to obtain a solution with a solid content of 20% by mass. The obtained solution was then applied onto a release PET film using a coater so that the thickness after drying would be 100 μm, and dried at 80° C. for 1 hour and at 110° C. for 1 hour to obtain an acrylic random copolymer A. The weight average molecular weight of the resulting acrylic random copolymer A was 300,000.

[0073] (Synthesis of Acrylic Random Copolymer B) In a 2L separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube, 75 parts by mass of butyl acrylate, 25 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of acrylic acid, and 500 parts by mass of ethyl acetate as a polymerization solvent were added. Next, nitrogen gas was blown in for 30 minutes to replace the atmosphere in the reaction vessel with nitrogen, and the reaction vessel was heated to 80°C while stirring. After 30 minutes, a polymerization initiator solution obtained by diluting 0.2 parts by mass of t-butylperoxy-2-ethylhexanoate with 5 parts by mass of ethyl acetate as a polymerization initiator was added dropwise to the reaction vessel over 2 hours. After that, the mixture was further reacted at 80°C for 6 hours, and then the reaction liquid was cooled to obtain an acrylic polymer solution. The obtained acrylic polymer solution was diluted with ethyl acetate to obtain a solution with a solid content of 20% by mass. The obtained solution was then applied onto a release PET film using a coater so that the thickness after drying would be 100 μm, and dried at 80° C. for 1 hour and at 110° C. for 1 hour to obtain an acrylic random copolymer B. The weight average molecular weight of the resulting acrylic random copolymer B was 80,000.

[0074] (viscosity) The viscosity of the obtained photocurable pressure-sensitive adhesive composition for printing was measured at 25° C. and 10 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., "VISCOMETER TV-22"). The results are shown in Table 1.

[0075] (Solid content of hardened product) The obtained photocurable pressure-sensitive adhesive composition for printing was applied to a release PET film (Nippa Corporation, "1-E", thickness 50 μm) using an applicator to a thickness of about 50 μm. Next, without sealing the coated surface, the coating was irradiated with UV-LED irradiation equipment (CS Corporation, "UVS01-01") at a wavelength of 365 nm and an illuminance of 500 mW / cm under atmospheric conditions. 2 The light is irradiated at 3000mJ / cm 2Thereafter, the air surface of the cured product was sealed with a release PET film (manufactured by Nippa Corporation, "1-C", thickness 38 μm) to obtain a laminate. Both release films were peeled off from the obtained laminate, and about 0.3 g of the cured product of the photocurable adhesive composition for printing was placed on an aluminum pan with a diameter of 10 cm and a height of 1 cm. A mixed solvent containing THF: acetone: ethanol in a mass ratio of 8:1:1 was gently added so that the cured sample would not scatter, and the sample was allowed to swell for about 2 hours. After that, the sample was dried at 110°C for 30 minutes, at 170°C for 1 hour, and at 190°C for 30 minutes. The mass of the aluminum pan and the dried sample after drying were weighed, and the solid content of the cured product was calculated using the following formula. The results are shown in Table 1. Solid content of cured product (%) = (total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) x 100

[0076] (Gel fraction of cured product) Both release films were peeled off from the laminate obtained in the same manner as in "(Solid content of cured product)" above, and 0.15 g of the cured product of the photocurable pressure-sensitive adhesive composition for printing was weighed into a glass bottle, which was then immersed in 30 g of tetrahydrofuran and immersed with shaking at 23°C for 36 hours. The cured product was then removed through a 200-mesh filter and dried by heating at 110°C for 1 hour. The mass of the cured product was then measured, and the gel fraction was calculated using the following formula. The results are shown in Table 1. Gel fraction of cured product (mass%) = (W2 / W1) x 100 W1: Mass of the cured product before immersion in tetrahydrofuran at 23°C W2: Mass of the cured product after immersion in tetrahydrofuran at 23°C, removal, and drying

[0077] <Evaluation> The following evaluations were carried out for each of the photocurable pressure-sensitive adhesive compositions for printing obtained in the Examples and Comparative Examples. The results are shown in Table 1.

[0078] (180° peel adhesive strength) Each of the obtained photocurable pressure-sensitive adhesive compositions for printing was applied to the inner treated surface of an easily adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") using an applicator (manufactured by Tester Sangyo Co., Ltd., "SA-201") to a thickness of about 50 μm. Thereafter, without sealing the coated surface, the coated surface was exposed to UV-LED irradiation at a wavelength of 365 nm and an illuminance of 500 mW / cm using a UV-LED irradiation device (manufactured by CCS Inc., "UVS01-01") in an atmospheric environment. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the film so that the cured product was heated to 100°C. The cured product was then sealed at the air side with a release PET film (Nippa Corporation, "1-C", thickness 38 μm) and cut to a width of 25 mm and a length of 200 mm (adhering surface 25 mm x 125 mm) to prepare a laminated film. The release PET film was then peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving a 2 kg roller back and forth once to obtain a test specimen. The test specimen was stored in a 25°C environment for 24 hours, and the 180° peel adhesive strength was measured by performing a 180° peel at a speed of 300 mm / min using a universal testing machine (A&D Corporation, "Tensilon RTI-1310").

[0079] (shear adhesive strength) The laminate obtained in the same manner as in "(Solid content of cured product)" above was cut to 25 mm x 25 mm, one release PET film (1-C) was peeled off, and the cured product was attached to a mirror-polished SUS substrate with a width of 25 mm, length of 100 mm, and thickness of 2 mm. Next, the other release PET film (1-E) was peeled off, and the mirror-polished surface of a similar SUS substrate was attached to the exposed cured product surface, and then the specimen was pressed at 215 N using a universal testing machine (manufactured by A&D, "Tensilon RTI-1310") and left to stand for 48 hours in an environment of 25°C to obtain a test specimen. The tensile shear adhesive strength (shear adhesive strength) of the obtained test specimen was measured at 25°C using a universal testing machine (manufactured by A&D, "Tensilon RTI-1310") according to a method conforming to JIS K 6850.

[0080] (Retention performance (creep resistance)) The laminate obtained in the same manner as in "(Solid content of cured product)" above was cut to 25 mm x 25 mm, one release PET film (1-C) was peeled off, and the cured product was attached to a mirror-polished SUS substrate with a width of 25 mm, length of 100 mm, thickness of 2 mm, and a 5 mm hole at the long edge. Next, the other release PET film (1-E) was peeled off, and the mirror-polished surface of a similar SUS substrate was attached to the exposed cured product surface, and then the specimen was pressed at 215 N using a universal testing machine (A&D Co., Ltd., "Tensilon RTI-1310") and left to stand for 48 hours in an environment of 25°C to obtain a test specimen. The obtained test piece was hung using an S-hook, and furthermore, a weight of 1 kg was hung from the lower SUS substrate. This was left at 25° C., and the time until the weight fell was measured, and the retention performance (creep resistance) was evaluated according to the following criteria. ◎: The weight did not fall even after 72 hours. ○: The time it took for the weight to fall was more than 24 hours but less than 72 hours. △: The time it took for the weight to fall was more than 6 hours but less than 24 hours. ×: The time it took for the weight to fall was less than 6 hours.

[0081] (Printability) (1) Coating method (1-1) Stencil printing The obtained photocurable pressure-sensitive adhesive composition for printing was applied to a release PET film (Nippa Corp., "1-E", thickness 50 μm) to a thickness of about 50 μm using a screen printer (Micro-Tech Corp., "LABTOP 38") and a 55 μm-thick SUS plate as a stencil plate, and stencil printing was performed. Next, a UV-LED irradiation device (CCS Corp., "UVS01-01") was used to irradiate the film with a wavelength of 365 nm and an illuminance of 500 mW / cm. 2 of light, with an irradiation dose of 3000mJ / cm 2 A cured product was obtained by irradiating the material in such a manner that the cured product satisfies the above criteria. (1-2) Screen printing The obtained photocurable pressure-sensitive adhesive composition for printing was applied in a pattern to a thickness of about 50 μm on the inner treated surface of an easily adhesive polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") using a screen printer (Micro-Tec Corporation, "LABTOP 38"), and screen-printed. A pattern-treated 80-mesh printing plate was used as the screen printing plate. Next, a UV-LED irradiation device (CCS Corporation, "UVS01-01") was used to irradiate the film with a wavelength of 365 nm and an illuminance of 500 mW / cm. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the material in such a manner that the cured product satisfies the above criteria. (1-3) Inkjet printing The obtained photocurable pressure-sensitive adhesive composition for printing was applied to a release PET film (Nippa's "1-E", thickness 50 μm) using an inkjet device (FUJIFILM's "Material Printer DMP-2831") to a thickness of about 2 μm. Next, using a UV-LED irradiation device (CCS's "UVS01-01"), the coating was irradiated with a wavelength of 365 nm and an illuminance of 500 mW / cm. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the material in such a manner that the cured product satisfies the above criteria.

[0082] (2) Evaluation of printability The resulting cured products were visually inspected and the printability was evaluated according to the following criteria. ○: When a cured product with uniform thickness and surface smoothness was obtained ×: Uneven thickness, surface irregularities or repelling

[0083] [Table 1] [Industrial Applicability]

[0084] According to the present invention, it is possible to provide a photocurable pressure-sensitive adhesive composition for printing that is excellent in repeated printability, photocurability in the presence of oxygen, and adhesiveness and retention performance after curing. Also, according to the present invention, it is possible to provide a cured product and a laminate using the photocurable pressure-sensitive adhesive composition for printing.

Claims

1. A composition comprising a (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin, and not a moisture-curable resin, The photopolymerization initiator has a weight average molecular weight of 800 or more.

1. A photocurable pressure-sensitive adhesive composition for printing.

2. A composition comprising a (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin, and not a moisture-curable resin, The photocurable pressure-sensitive adhesive composition for printing is applied to a substrate to a thickness of 40 μm or more and 60 μm or less, and the coated surface is not sealed, and is exposed to light at a wavelength of 365 nm and an illuminance of 500 mW / cm in an atmospheric environment. ２ The light is irradiated at a dose of 3000 mJ / cm ２ The solid content of the cured product obtained by irradiating the cured product so as to satisfy the above condition is 90% or more, and the gel content of the cured product is 25% by mass or more and 60% by mass or less.

1. A photocurable pressure-sensitive adhesive composition for printing.

3. The photocurable pressure-sensitive adhesive composition for printing according to claim 2 , wherein the photopolymerization initiator has a weight average molecular weight of 800 or more.

4. 3. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, wherein the photopolymerization initiator is a Norrish I type photopolymerization initiator having a weight average molecular weight of 800 or more.

5. 5. The photocurable pressure-sensitive adhesive composition for printing according to claim 4, wherein the photopolymerization initiator has two or more carbonyl groups in one molecule that contribute to a Norrish I type cleavage reaction.

6. 6. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, 2, 3, 4 or 5, wherein the thermoplastic resin has a weight average molecular weight of 100,000 or more and 1,000,000 or less.

7. 7. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, wherein the thermoplastic resin is a block copolymer.

8. 8. The photocurable pressure-sensitive adhesive composition for printing according to claim 7, wherein the thermoplastic resin is a (meth)acrylic / styrene block copolymer.

9. The photocurable adhesive composition for printing according to claim 1, 2, 3, 4, 5, 6, 7 or 8, further comprising a nitrogen-containing vinyl compound, and the content of the nitrogen-containing vinyl compound in 100 parts by mass of the photocurable adhesive composition for printing is 0.1 parts by mass or more and 5.0 parts by mass or less.

10. 10. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, further comprising an antifoaming agent.

11. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, further comprising a leveling agent.

12. 12. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, which does not contain a solvent or contains 1 part by mass or less of a solvent per 100 parts by mass of the photocurable pressure-sensitive adhesive composition for printing.

13. 13. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, which is used for screen printing and has a viscosity of 1 Pa·s or more and 400 Pa·s or less when measured using an E-type viscometer at 25° C. and 10 rpm.

14. 13. The photocurable pressure-sensitive adhesive composition for printing according to claim 1, which is used for inkjet printing and has a viscosity of 0.001 Pa·s or more and 10 Pa·s or less when measured using an E-type viscometer at 25° C. and 10 rpm.

15. A cured product obtained by curing the photocurable pressure-sensitive adhesive composition for printing according to claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , or 14 .

16. 16. The cured product according to claim 15, having a solids content of 90% or more and a gel content of 25% by mass or more and 60% by mass or less.

17. A laminate having a release-treated film on at least one surface of the cured product according to claim 15 or 16.

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