Ultraviolet-curable adhesive composition and method for producing laminate

Abstract

The present invention is an ultraviolet-curable adhesive composition comprising a maleimide derivative, an ultraviolet-polymerizable compound, a photopolymerization initiator, and an amine compound. When this maleimide derivative contains a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom, the maleimide derivative either does not contain a maleimide derivative that has a structure in which hydrogen is bonded to a heteroatom, or the content in the maleimide derivative of maleimide derivative having a structure in which hydrogen is bonded to a heteroatom is less than 50 mass%. When the maleimide derivative contains only maleimide derivative having a structure in which hydrogen is bonded to a heteroatom, the content of this maleimide derivative having a structure in which hydrogen is bonded to a heteroatom is not more than 9.8 parts by mass per 100 parts by mass of the ultraviolet-polymerizable compound. The ultraviolet-polymerizable compound contains at least 20 mass% of monomer that can be a hydrogen donor. The photopolymerization initiator contains at least one selection from the group consisting of hydrogen-abstracting photopolymerization initiators and polymeric photopolymerization initiators. With regard to the amine compound, the content in this amine compound of amine compound that does not have a structure in which hydrogen is bonded to a heteroatom is at least 50 mass%. The content in the ultraviolet-curable adhesive composition of the amine compound, per 100 parts by mass of the total of the maleimide derivative and ultraviolet-polymerizable compound, is 0.1 parts by mass to 10 parts by mass.

Description

Ultraviolet-curable pressure-sensitive adhesive composition and method for producing laminate

[0001] The present invention relates to an ultraviolet-curable pressure-sensitive adhesive composition and a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.

[0002] Adhesives are used to bond electronic components inside electronic devices such as smartphones and PCs. In a typical adhesive bonding method, a pressure-sensitive adhesive sheet is first prepared, with separators disposed on both sides of the adhesive. The adhesive sheet is then cut to the desired shape. One separator is then peeled from the cut adhesive sheet, and one side of the exposed adhesive is bonded to a first adherend. The other separator is then peeled off, and the other side of the exposed adhesive is bonded to a second adherend. This method generates waste because a portion of the adhesive sheet is discarded after cutting. Furthermore, air bubbles can sometimes be trapped at the bonded surface.

[0003] In response to this, a method has been investigated in which a pressure-sensitive adhesive composition is printed in a desired shape and then bonded to an adherend, without producing a pressure-sensitive adhesive sheet, which can reduce waste generation and prevent air bubbles from forming at the bonding surface.

[0004] For example, Patent Document 1 discloses an invention for providing a radiation-curable pressure-sensitive adhesive composition that allows for fine patterning and exhibits high adhesion to various adherends such as metals and plastics. 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.

[0005] Furthermore, Patent Document 2 discloses an invention for providing a photocurable adhesive composition that, even when irradiated with light in the presence of oxygen, provides a laminate having adhesive strength equivalent to that in the absence of oxygen. Patent Document 2 describes a photocurable adhesive composition containing (A) a (meth)acrylate oligomer, (B) a monofunctional (meth)acrylic monomer, (C) a di- to tetra-functional (meth)acrylic monomer, (D) a photoinitiator, (E) a tackifier having a softening point of 70 to 150°C, and (F) a liquid plasticizer.

[0006] Patent Document 1: JP 2013-216742 A, International Publication No. 2016 / 163152

[0007] As described above, the method of printing a pressure-sensitive adhesive composition into a desired shape and then laminating it to an adherend without preparing a pressure-sensitive adhesive sheet can reduce waste generation and prevent air bubbles from forming at the lamination surface. On the other hand, UV curing is desirable as a method for curing a pressure-sensitive adhesive composition to avoid heating the adherend. However, when attempting to obtain a highly curable cured product by UV curing in the presence of oxygen, the crosslinking density increases, resulting in poor stress relaxation properties, and as a result, the cured product may have poor impact resistance. Furthermore, if the pressure-sensitive adhesive composition is exposed to oxygen without being covered with a separator during curing, the outermost surface may not cure, and sufficient adhesiveness may not be obtained. Furthermore, poor curability at the outermost surface may cause bleeding, and the presence of this bleeding may cause slippage in the shear direction when the pressure-sensitive adhesive composition is used to laminate an adherend.

[0008] The present invention aims to provide an ultraviolet-curable pressure-sensitive adhesive composition that has excellent printability, is resistant to cohesive failure in a cured product, and has excellent impact resistance, and an ultraviolet-curable pressure-sensitive adhesive composition that has excellent adhesion and low bleeding properties. Another object of the present invention is to provide a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.

[0009] Disclosure 1 relates to an ultraviolet-curable pressure-sensitive adhesive composition containing a maleimide derivative, an ultraviolet-polymerizable compound, a photopolymerization initiator, and an amine compound, wherein when the maleimide derivative contains a maleimide derivative not having a structure in which hydrogen is bonded to a heteroatom, the maleimide derivative does not contain a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom, or the content of the maleimide derivative having a structure in which hydrogen is bonded to the heteroatom in the maleimide derivative is less than 50 mass %, and when the maleimide derivative contains only a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom, the content of the maleimide derivative having a structure in which hydrogen is bonded to the heteroatom relative to 100 mass parts of the ultraviolet-polymerizable compound is less than 50 mass %. The ultraviolet-curable pressure-sensitive adhesive composition includes: a maleimide derivative having a hydrogen-bonded structure in an amount of 9.8 parts by mass or less; the ultraviolet-polymerizable compound includes a monomer capable of acting as a hydrogen donor in an amount of 20% by mass or more; the photopolymerization initiator includes at least one selected from the group consisting of a hydrogen-abstraction photopolymerization initiator and a polymeric photopolymerization initiator; the amine compound includes an amine compound having no structure in which a hydrogen is bonded to a heteroatom in an amount of 50% by mass or more; and the amount of the amine compound is 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound. Disclosure 2 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1, wherein the amount of the maleimide derivative is 0.1 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the ultraviolet-polymerizable compound. Disclosure 3 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1 or 2, wherein the monomer capable of serving as a hydrogen donor is a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond. Disclosure 4 is a method for producing an ultraviolet-curable pressure-sensitive adhesive composition by applying the ultraviolet-curable pressure-sensitive adhesive composition to a substrate, and then, without sealing the coated surface, applying ultraviolet light at a wavelength of 365 nm and an illuminance of 20 mW / cm under atmospheric conditions. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1, 2, or 3 is an ultraviolet-curable pressure-sensitive adhesive composition containing a maleimide derivative, an ultraviolet-polymerizable compound, and a photopolymerization initiator, wherein the content of the maleimide derivative is 8 parts by mass or more relative to 100 parts by mass of the ultraviolet-polymerizable compound, and the ultraviolet-curable pressure-sensitive adhesive composition is applied to a substrate, and the coated surface is not sealed, and the composition is cured under atmospheric conditions at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２and a cured product having a thickness of 100 μm, the cured product having a reaction rate of 88% or higher, obtained by simultaneously irradiating the ultraviolet rays and the ultraviolet ray source to the ultraviolet ray source so that the reaction rate is 88% or higher. Disclosure 6 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 5, further containing an amine compound. Disclosure 7 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, or 6, wherein the ultraviolet-polymerizable compound contains 50 mass% or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond. Disclosure 8 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, or 7, wherein the ultraviolet-polymerizable compound contains at least one selected from the group consisting of a (meth)acrylic monomer and a vinyl monomer. Disclosure 9 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 8, wherein the ultraviolet-polymerizable compound contains a polyfunctional (meth)acrylic monomer. Disclosure 10 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 9, wherein the ultraviolet-polymerizable compound comprises a polyfunctional (meth)acrylic monomer, and the content of the polyfunctional (meth)acrylic monomer is 25 parts by mass or less per 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound excluding the polyfunctional (meth)acrylic monomer. Disclosure 11 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 10, wherein the content of the polyfunctional (meth)acrylic monomer is 20 parts by mass or less per 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound excluding the polyfunctional (meth)acrylic monomer. Disclosure 12 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, wherein the content of the photopolymerization initiator is 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound. The present disclosure 13 is the ultraviolet-curable pressure-sensitive adhesive composition according to disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, further comprising a thermoplastic resin. The present disclosure 14 is the ultraviolet-curable pressure-sensitive adhesive composition according to disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, further comprising a tackifier.Disclosure 15 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, having a viscosity of 10 mPa·s or more and 75,000 mPa·s or less at 25° C. Disclosure 16 is a method of applying the ultraviolet-curable pressure-sensitive adhesive composition to a substrate and applying the composition to a substrate at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, wherein the glass transition temperature of a 100 μm-thick cured product obtained by simultaneously irradiating ultraviolet rays and ultraviolet rays onto a first adherend such that the ultraviolet-curable pressure-sensitive adhesive composition is -60°C or higher and 20°C or lower. Disclosure 17 is a method for producing a laminate, comprising the steps of applying the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 onto a first adherend and exposing the composition to light to form an adhesive layer, and attaching a second adherend to the adhesive layer, wherein the method for applying the ultraviolet-curable pressure-sensitive adhesive composition is inkjet printing, screen printing, spray coating, spin coating, gravure offset, or reverse offset printing, and the ultraviolet-curable pressure-sensitive adhesive composition is partially coated onto the first adherend. The present invention is described in detail below.

[0010] Hereinafter, the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1 will also be referred to as the "ultraviolet-curable pressure-sensitive adhesive composition of Invention 1," and the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 5 will also be referred to as the "ultraviolet-curable pressure-sensitive adhesive composition of Invention 2." Furthermore, matters common to the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1 and the ultraviolet-curable pressure-sensitive adhesive composition of Invention 2 will be described as the "ultraviolet-curable pressure-sensitive adhesive composition of the present invention." The present inventors investigated the use of a specific maleimide derivative, a specific ultraviolet-polymerizable compound, a specific photopolymerization initiator, and a specific amine compound in a specific combination in a specific content ratio in an ultraviolet-curable pressure-sensitive adhesive composition. As a result, they found that an ultraviolet-curable pressure-sensitive adhesive composition can be obtained that exhibits excellent printability, is resistant to cohesive failure in a cured product, and exhibits excellent impact resistance, thereby completing Invention 1. The present inventors have also investigated the use of a combination of a maleimide derivative, an ultraviolet-polymerizable compound, and a photopolymerization initiator in an ultraviolet-curable pressure-sensitive adhesive composition, adjusting the content of the photopolymerization initiator to a specific range, and curing the ultraviolet-curable pressure-sensitive adhesive composition under specific conditions to achieve a reaction rate of a specific value or higher. As a result, they have found that an ultraviolet-curable pressure-sensitive adhesive composition having excellent adhesion and low bleeding properties can be obtained, leading to the completion of Invention 2.

[0011] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention contains a maleimide derivative. The reaction system of the maleimide derivative basically proceeds via a hydrogen abstraction (Type II) reaction. Photoradical polymerization via a hydrogen abstraction reaction is less susceptible to oxygen inhibition, thereby enabling enhanced surface curability. Furthermore, photoradical polymerization via a hydrogen abstraction reaction produces a branched polymer, rather than a linear polymer as in the cleavage (Type I) reaction, and also exhibits enhanced cohesive strength. Therefore, by incorporating the maleimide derivative in combination with a UV-polymerizable compound described below, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention can produce a cured product that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced surface curability and cohesive strength. In this specification, the term "maleimide derivative" refers to a compound having a maleimide group. Although the maleimide derivative is UV-polymerizable, it is not considered a UV-polymerizable compound described below.

[0012] In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, when the maleimide derivative contains a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom, the maleimide derivative does not contain a maleimide derivative that has a structure in which hydrogen is bonded to a heteroatom, or the content of the maleimide derivative that has a structure in which hydrogen is bonded to the heteroatom in the maleimide derivative is less than 50 mass%. When the maleimide derivative contains only a maleimide derivative that has a structure in which hydrogen is bonded to a heteroatom, the content of the maleimide derivative that has a structure in which hydrogen is bonded to the heteroatom is 9.8 mass parts or less per 100 mass parts of the ultraviolet-polymerizable compound. This allows the ultraviolet-curable pressure-sensitive adhesive composition of the present invention to produce a cured product with excellent impact resistance. It is particularly preferable that the maleimide derivative contains only a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom.

[0013] Examples of the structure in which hydrogen is bonded to a hetero atom include a hydroxyl group, a carboxyl group, a primary amino group, and a secondary amino group.

[0014] Among the maleimide derivatives not having a structure in which hydrogen is bonded to a heteroatom, examples of monofunctional maleimides include N-cyclohexylmaleimide, N-laurylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-benzylmaleimide, N-phenylmethylmaleimide, N-octadecenylmaleimide, N-dodecenylmaleimide, etc. Among these, at least one selected from the group consisting of N-cyclohexylmaleimide and N-laurylmaleimide is preferred. Furthermore, examples of polyfunctional maleimides among the maleimide derivatives that do not have a structure in which hydrogen is bonded to a heteroatom 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 Examples of suitable maleimide derivatives include N,N'-4,4'-biphenylene bismaleimide, 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-mentioned monofunctional maleimide may be used in combination with these polyfunctional maleimides as the maleimide derivative not having a structure in which hydrogen is bonded to a heteroatom; however, using a large amount of polyfunctional maleimide in combination is not preferred because the gel fraction increases.

[0015] Examples of the maleimide derivative having a structure in which hydrogen is bonded to the hetero atom include N-(4-carboxycyclohexylmethyl)maleimide, 4-hydroxyphenylmaleimide, and N-(4-anilinophenyl)maleimide.

[0016] Among the maleimide derivatives in the ultraviolet-curable pressure-sensitive adhesive composition of the second invention, 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, and N-methylmaleimide. Examples of suitable maleimide include N-ethylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-benzylmaleimide, N-phenylmethylmaleimide, N-(2,4,6-tribromophenyl)maleimide, N-[3-(triethoxysilyl)propyl]maleimide, N-octadecenylmaleimide, N-dodecenylmaleimide, N-(2-methoxyphenyl)maleimide, N-(2,4,6-trichlorophenyl)maleimide, and N-(1-hydroxyphenyl)maleimide. Among these, maleimide derivatives that do not have a structure in which hydrogen is bonded to a heteroatom are preferably selected from the viewpoint of increasing the reaction rate. Furthermore, maleimide derivatives that have a structure in which hydrogen is bonded to a heteroatom may also be used from the viewpoint of improving adhesive strength. Specifically, the monofunctional maleimide is preferably at least one selected from the group consisting of N-cyclohexylmaleimide, 4-hydroxyphenylmaleimide, and N-(4-carboxycyclohexylmethyl)maleimide.Furthermore, examples of the polyfunctional maleimides among the maleimide derivatives 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 suitable 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-mentioned monofunctional maleimide may be used in combination with these polyfunctional maleimides as the maleimide derivative, but using a large amount of polyfunctional maleimide in combination is not preferred because the gel fraction increases.

[0017] In the ultraviolet-curable pressure-sensitive adhesive composition of invention 1, the content of the maleimide derivative is preferably 0.1 parts by mass at the lower limit and 20 parts by mass at the upper limit relative to 100 parts by mass of the ultraviolet-polymerizable compound described below. By setting the content of the maleimide derivative in the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 within the above range, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better curability. The content of the maleimide derivative in the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 is more preferably 0.5 parts by mass at the lower limit and 10 parts by mass at the upper limit. In the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, the content of the maleimide derivative is more preferably 8 parts by mass at the lower limit relative to 100 parts by mass of the ultraviolet-polymerizable compound described below. By setting the content of the maleimide derivative in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 to 8 parts by mass or more, the obtained ultraviolet-curable pressure-sensitive adhesive composition has excellent surface curability. The lower limit of the content of the maleimide derivative in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is preferably 10 parts by mass, more preferably 12 parts by mass, and even more preferably 14 parts by mass. From the viewpoint of the reaction rate, the upper limit of the content of the maleimide derivative in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 relative to 100 parts by mass of the ultraviolet-polymerizable compound described below is preferably 70 parts by mass, and more preferably 30 parts by mass.

[0018] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention contains an ultraviolet-polymerizable compound. As described above, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention contains the ultraviolet-polymerizable compound in combination with the maleimide derivative, thereby making it possible to obtain a cured product that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced curability and cohesive strength.

[0019] In the ultraviolet-curable pressure-sensitive adhesive composition of invention 1, the ultraviolet-polymerizable compound contains a monomer capable of serving as a hydrogen donor. Furthermore, in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, the ultraviolet-polymerizable compound preferably contains a monomer capable of serving as a hydrogen donor. In this specification, the term "monomer capable of serving as a hydrogen donor" refers to a monomer having hydrogen capable of being used in a hydrogen abstraction reaction.

[0020] The hydrogen donor monomer is preferably a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond. When the hydrogen donor monomer is a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond, it can more easily provide hydrogen to a hydrogen abstraction reaction. Of these, the hydrogen donor monomer is more preferably a monomer having at least one structure selected from the group consisting of an ether bond, a phenoxy group, and an amide bond.

[0021] In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, the lower limit of the content of the monomer capable of serving as a hydrogen donor in the ultraviolet-polymerizable compound is 20% by mass. When the content of the monomer capable of serving as a hydrogen donor in the ultraviolet-polymerizable compound is 20% by mass or more, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention exhibits excellent curability. A preferred lower limit of the content of the monomer capable of serving as a hydrogen donor in the ultraviolet-polymerizable compound is 35% by mass. Furthermore, from the viewpoint of impact resistance, a preferred upper limit of the content of the monomer capable of serving as a hydrogen donor in the ultraviolet-polymerizable compound is 90% by mass, more preferably 70% by mass. In particular, in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention, the ultraviolet-polymerizable compound preferably contains 50% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond. When the ultraviolet-polymerizable compound contains 50 mass% or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond, the resulting ultraviolet-curable pressure-sensitive adhesive composition exhibits superior surface curability and impact resistance of the cured product. More preferably, the ultraviolet-polymerizable compound contains 70 mass% or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond per 100 mass% of the (meth)acrylic monomer. Furthermore, the (meth)acrylic monomer may contain only a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.

[0022] The ultraviolet-polymerizable compound preferably contains at least one selected from the group consisting of (meth)acrylic monomers and vinyl monomers. When the ultraviolet-polymerizable compound contains at least one selected from the group consisting of the (meth)acrylic monomers and vinyl monomers, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better curability. 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.

[0023] The (meth)acrylic monomer preferably contains a monofunctional (meth)acrylic monomer from the viewpoint of adhesion to various substrates, etc. In this specification, the "monofunctional (meth)acrylic monomer" refers to a monomer having one (meth)acryloyl group in one molecule.

[0024] Examples of the monofunctional (meth)acrylic monomer include monofunctional (meth)acrylic acid ester compounds and monofunctional (meth)acrylamide compounds.

[0025] 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, and 4-hydroxybutyl (meth)acrylate. , cyclohexyl (meth)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, 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, imide (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-ethyloxetan-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, and the like. In this specification, the term "(meth)acrylate" means acrylate or methacrylate.

[0026] 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.

[0027] The ultraviolet-polymerizable compound may contain a polyfunctional (meth)acrylic monomer as the (meth)acrylic monomer. The polyfunctional (meth)acrylic monomer serves as a cross-linking component. In this specification, the "polyfunctional (meth)acrylic monomer" refers to a monomer having two or more (meth)acryloyl groups in one molecule.

[0028] Examples of the polyfunctional (meth)acrylic monomer include polyfunctional urethane (meth)acrylate, polyfunctional (meth)acrylic acid ester compound, polyfunctional epoxy (meth)acrylate, etc. In this specification, the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have reacted with (meth)acrylic acid.

[0029] 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.

[0030] Examples of the isocyanate compound that can be used as 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.

[0031] Furthermore, 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, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0032] Examples of the (meth)acrylic acid derivatives 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)acrylates include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate. Examples of the dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohols include trimethylolethane, trimethylolpropane, and glycerin.

[0033] 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, trimethyl 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.

[0034] 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.

[0035] In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, the preferred upper limit of the content of the polyfunctional (meth)acrylic monomer relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compounds excluding the polyfunctional (meth)acrylic monomer is 25 parts by mass. When the content of the polyfunctional (meth)acrylic monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 25 parts by mass or less, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better printability and impact resistance of the cured product. A more preferred upper limit of the content of the polyfunctional (meth)acrylic monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 20 parts by mass. Furthermore, from the viewpoints of impact resistance test strength and adhesive strength, a preferred lower limit of the content of the polyfunctional (meth)acrylic monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 5 parts by mass relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compounds excluding the polyfunctional (meth)acrylic monomer. In the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, the content of the polyfunctional (meth)acrylic monomer relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound excluding the polyfunctional (meth)acrylic monomer is preferably 1 part by mass at the lower limit and 30 parts by mass at the upper limit. When the content of the polyfunctional (meth)acrylic monomer in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is within this range, the adhesion of the cured product made from the obtained ultraviolet-curable pressure-sensitive adhesive composition becomes more excellent. The content of the polyfunctional (meth)acrylic monomer in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is more preferably 3 parts by mass at the lower limit and more preferably 25 parts by mass at the upper limit, even more preferably 20 parts by mass at the upper limit, and particularly preferably 15 parts by mass at the upper limit.

[0036] The vinyl monomer is preferably an amide compound having a vinyl group, more preferably a cyclic amide compound having a vinyl group.

[0037] The cyclic amide compound having a vinyl group preferably has a lactam structure, and more preferably is a compound represented by the following formula (1):

[0038]

[0039] In formula (1), n ​​represents an integer of 2 to 6.

[0040] Examples of the compound represented by the formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, etc. Among these, N-vinyl-ε-caprolactam is preferred.

[0041] Among the above-mentioned amide compounds having a vinyl group, examples of compounds other than the above-mentioned cyclic amide compounds having a vinyl group include N-vinylacetamide.

[0042] In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, when the ultraviolet-polymerizable compound contains the (meth)acrylic monomer and the vinyl monomer, the preferred lower limit of the content of the vinyl monomer relative to 100 parts by mass of the (meth)acrylic monomer is 20 parts by mass, and the preferred upper limit is 80 parts by mass. When the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 20 parts by mass or more, the resulting ultraviolet-curable pressure-sensitive adhesive composition has superior curability. When the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 80 parts by mass or less, the resulting ultraviolet-curable pressure-sensitive adhesive composition can also have excellent properties other than curability. A more preferred lower limit of the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 40 parts by mass, and a more preferred upper limit is 60 parts by mass. Furthermore, in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, when the ultraviolet-polymerizable compound contains the (meth)acrylic monomer and the vinyl monomer, a preferred lower limit of the content of the vinyl monomer per 100 parts by mass of the (meth)acrylic monomer is 8 parts by mass, and a preferred upper limit is 80 parts by mass. When the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 8 parts by mass or more, the resulting ultraviolet-curable pressure-sensitive adhesive composition has superior curability. When the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 80 parts by mass or less, the resulting ultraviolet-curable pressure-sensitive adhesive composition can also have excellent properties other than curability. A more preferred lower limit of the content of the vinyl monomer in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 15 parts by mass, and a more preferred upper limit is 60 parts by mass.

[0043] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator. In the ultraviolet-curable pressure-sensitive adhesive composition of invention 1, the photopolymerization initiator comprises at least one selected from the group consisting of a hydrogen-abstraction photopolymerization initiator and a polymeric photopolymerization initiator. By using such a photopolymerization initiator in combination with an amine compound described below, the resulting ultraviolet-curable pressure-sensitive adhesive composition can produce a cured product that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced surface curability and cohesive strength. Furthermore, in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, the photopolymerization initiator preferably comprises a hydrogen-abstraction photopolymerization initiator. By using the hydrogen-abstraction photopolymerization initiator in combination with an amine compound described below as the photopolymerization initiator, the resulting ultraviolet-curable pressure-sensitive adhesive composition can produce a cured product that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced surface curability and cohesive strength.

[0044] The hydrogen abstraction photopolymerization initiator is preferably a benzophenone-based photopolymerization initiator. Examples of the benzophenone-based photopolymerization initiator include benzophenone, 4-chlorobenzophenone, 4,4'-dimethylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, methyl o-benzoylbenzoate, 3,3'-dimethyl-4-methoxybenzophenone, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 4-morpholinobenzophenone, 4,4'-diphenoxybenzophenone, 4-hydroxybenzophenone, 2-carboxybenzophenone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methyl-propionyl)-benzyl)-phenyl)-2-methyl-propan-1-one, 1-(4-(4-benzoylphenylthio)phenyl)-2-tosyl-2-methyl-1-propanone, and 3-ketocoumarin.

[0045] Among the hydrogen abstraction photopolymerization initiators, commercially available examples include Esacure TZT and Omnirad 4MBZ (both manufactured by IGM Resins).

[0046] Examples of the polymeric photopolymerization initiator include a polymer of ethyl(2,4,6-trimethylbenzoyl)phenylphosphonate, polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate, and bis(benzophenone-2-carboxylic acid) polyethylene glycol ester.

[0047] Among the above polymeric photopolymerization initiators, commercially available ones include, for example, Omnipol TP, Omnipol 910, and Omnipol 2702 (all manufactured by IGM Resins).

[0048] In the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, a cleavage-type photopolymerization initiator can also be used as the photopolymerization initiator. Examples of the cleavage-type photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0049] In the ultraviolet-curable pressure-sensitive adhesive composition of invention 1, the content of the photopolymerization initiator is preferably 0.5 parts by mass at the lower limit and 15 parts by mass at the upper limit, relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound. When the content of the photopolymerization initiator in the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 is within this range, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better storage stability, curability, and adhesion. The content of the photopolymerization initiator in the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 is more preferably 1 part by mass at the lower limit and 10 parts by mass at the upper limit, and even more preferably 3 parts by mass and 9 parts by mass at the upper limit. In the ultraviolet-curable pressure-sensitive adhesive composition of invention 2, the content of the photopolymerization initiator is preferably 1 part by mass at the lower limit and 10 parts by mass at the upper limit, relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound. When the content of the photopolymerization initiator in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is within this range, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better storage stability, curability, and adhesion. A more preferred lower limit of the content of the photopolymerization initiator in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 3 parts by mass, and a more preferred upper limit is 9 parts by mass.

[0050] The ultraviolet-curable pressure-sensitive adhesive composition of invention 1 contains an amine compound. Preferably, the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 further contains an amine compound. As described above, by using the amine compound in combination with the hydrogen-abstraction photopolymerization initiator, it becomes possible to obtain a cured product from the ultraviolet-curable pressure-sensitive adhesive composition that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced curability and cohesive strength.

[0051] In the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1, the amine compound contains 50% by mass or more of an amine compound that does not have a structure in which hydrogen is bonded to a heteroatom. By using an amine compound containing 50% by mass or more of an amine compound that does not have a structure in which hydrogen is bonded to a heteroatom, the obtained ultraviolet-curable pressure-sensitive adhesive composition can produce a cured product that is less susceptible to bleeding due to reduced surface curability and cohesive failure due to reduced surface curability and cohesive strength. In the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1, the amine compound contains preferably 75% by mass or more, and most preferably 100% by mass, of an amine compound that does not have a structure in which hydrogen is bonded to a heteroatom.

[0052] Examples of the amine compound not having a structure in which hydrogen is bonded to a heteroatom include (bis-N,N-(4-dimethylaminobenzoyl)oxyethylene-1-yl)-methylamine, bis(2-morpholinoethyl)ether, 1-methyl 10-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate.

[0053] Commercially available amine compounds that do not have a structure in which hydrogen is bonded to a heteroatom include, for example, Esacure A198 (manufactured by IGM Resins), U-cat 660 (manufactured by San-Apro Co., Ltd.), Eversorb 93 (manufactured by Everlight Chemical Co.), Adekastab LA-52, and Adekastab LA-72 (all manufactured by ADEKA Corporation).

[0054] In the ultraviolet-curable pressure-sensitive adhesive composition of the second invention, examples of the amine compound include (bis-N,N-(4-dimethylaminobenzoyl)oxyethylene-1-yl)-methylamine, bis(2-morpholinoethyl)ether, 1-methyl 10-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.

[0055] In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, the lower limit of the content of the amine compound relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound is 0.1 parts by mass, and the upper limit is 10 parts by mass. When the content of the amine compound in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 0.1 parts by mass or more, the resulting ultraviolet-curable pressure-sensitive adhesive composition has excellent curability. When the content of the amine compound in the ultraviolet-curable pressure-sensitive adhesive composition of the first invention is 10 parts by mass or less, the resulting cured product of the ultraviolet-curable pressure-sensitive adhesive composition is less likely to suffer from cohesive failure. In the ultraviolet-curable pressure-sensitive adhesive composition of the first invention, the lower limit of the content of the amine compound is preferably 1.5 parts by mass, more preferably 2.5 parts by mass, and the upper limit is preferably 7 parts by mass, even more preferably 5 parts by mass. In the ultraviolet-curable pressure-sensitive adhesive composition of the second invention, the lower limit of the content of the amine compound relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound is preferably 1.5 parts by mass, and the upper limit is preferably 8 parts by mass. When the content of the amine compound in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 1.5 parts by mass or more, the resulting ultraviolet-curable pressure-sensitive adhesive composition has superior surface curability. When the content of the amine compound in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 8 parts by mass or less, the resulting cured product of the ultraviolet-curable pressure-sensitive adhesive composition is less likely to suffer from cohesive failure. A more preferred lower limit of the content of the amine compound in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is 2.5 parts by mass, and a more preferred upper limit is 5 parts by mass.

[0056] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention may further contain a thermoplastic resin. The thermoplastic resin is preferably a compound that does not contain a reactive double bond or that has a reactive double bond but does not substantially exhibit photoradical polymerization reactivity.

[0057] Examples of the thermoplastic resin include solventless acrylic polymers and polymers obtained by drying a polymer dissolved in a solvent. Examples of the solventless acrylic polymer include a polymer of at least one monomer selected from (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 20 carbon atoms, or a copolymer of the monomer with another copolymerizable monomer. Commercially available solventless acrylic polymers include the ARUFON-UP1000 series, UH2000 series, and UC3000 series (all manufactured by Toagosei Co., Ltd.), the Kurariti LA series, and the Kurariti LK series (all manufactured by Kuraray Co., Ltd.), etc.

[0058] The content of the thermoplastic resin is preferably 5 parts by mass or less and 100 parts by mass or less per 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound. When the content of the thermoplastic resin is within this range, the viscosity of the obtained ultraviolet-curable pressure-sensitive adhesive composition is improved, a thick coating film can be formed, printability is improved, and a decrease in adhesiveness at high temperatures can be suppressed. The lower limit of the content of the thermoplastic resin is more preferably 20 parts by mass, and the upper limit is more preferably 60 parts by mass.

[0059] The ultraviolet-curable pressure-sensitive adhesive composition may contain a thermosetting resin or a moisture-curing resin, and thus may contain a material that exhibits reactivity to a trigger such as heat or moisture.

[0060] Examples of the thermosetting resin include epoxy resin, phenol resin, urea resin, melamine resin, etc. Among these, epoxy resin is preferred. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, biphenyl novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, anthracene type epoxy resin, epoxy resin having an adamantane skeleton, epoxy resin having a tricyclodecane skeleton, and epoxy resin having a triazine nucleus in the skeleton.

[0061] When using the thermosetting resin, it is preferable to include a thermosetting agent in the ultraviolet-curable pressure-sensitive adhesive composition. Examples of the thermosetting agent include cyanate ester compounds (cyanate ester curing agents), phenolic compounds (phenolic thermosetting agents), amine compounds (amine thermosetting agents), thiol compounds (thiol thermosetting agents), imidazole compounds, phosphine compounds, acid anhydrides, active ester compounds, and dicyandiamide. When using an epoxy resin as the thermosetting resin, a photocationic polymerization initiator may be included in the ultraviolet-curable pressure-sensitive adhesive composition. This facilitates gradual curing even after the first stage of irradiation with active energy rays. As a result, the resulting ultraviolet-curable pressure-sensitive adhesive composition has even better initial adhesive strength. Even when the epoxy resin and the photocationic polymerization initiator are included, the epoxy resin is not considered to be the ultraviolet-polymerizable compound.

[0062] The photocationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon irradiation with light, and may be either an ionic photoacid generating type or a nonionic photoacid generating type.

[0063] Examples of the ionic photoacid generating cationic photopolymerization initiator include the following: Aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe cation is used as the cationic initiator, and BF is used as the anionic initiator. ４ － , P.F. ６ － , SbF ６ － , or (BX ４ ) － The X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups.

[0064] Examples of the aromatic sulfonium salt include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(diphenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, and diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate. , triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, and the like.

[0065] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0066] Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1-(naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0067] Examples of the (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salt include (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0068] Examples of the nonionic photoacid generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinone, and N-hydroxyimidesulfonates.

[0069] The cationic photopolymerization initiator may be used alone or in combination of two or more. The content of the cationic photopolymerization initiator is preferably 0.1 parts by mass or less and 10 parts by mass or less relative to 100 parts by mass of the epoxy resin.

[0070] Examples of the moisture-curing resin include moisture-curing urethane resins and resins having crosslinkable silyl groups. Among these, moisture-curing urethane resins are preferred. Moisture-curing urethane resins have a urethane bond and an isocyanate group, and the isocyanate group in the molecule reacts with moisture to cure. The isocyanate group is preferably located at the end of the molecule. The moisture-curing urethane resin may have a radical-reactive functional group. Note that even when the moisture-curing urethane resin has a radical-reactive functional group, the moisture-curing urethane resin is not considered to be the ultraviolet-polymerizable compound. The moisture-curing urethane resin can be obtained by reacting a polyol compound having two or more hydroxyl groups per molecule with a polyisocyanate compound having two or more isocyanate groups per molecule.

[0071] When the moisture-curable resin is used, it is preferable to add a moisture-curing accelerator to the ultraviolet-curable pressure-sensitive adhesive composition in order to improve the curing rate during moisture curing. Examples of the moisture-curing accelerator include a compound having a morpholine skeleton, a compound having a piperidine skeleton, and a compound having a piperazine skeleton.

[0072] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention may further contain a tackifier, such as a rosin-based resin or a terpene-based resin.

[0073] Examples of the rosin-based resin include rosin diols. The rosin diols are not particularly limited as long as they are rosin-modified diols having two rosin skeletons and two hydroxyl groups per molecule. Diols containing a rosin component in the molecule are called rosin polyols, and these include polyether-type diols, such as polypropylene glycol (PPG), and polyester-type diols, such as condensation polyester polyols, lactone polyester polyols, and polycarbonate diols, in which the skeleton excluding the rosin component is polyether-type diols. Examples of the rosin diols include rosin esters obtained by reacting rosin with polyhydric alcohols, epoxy-modified rosin esters obtained by reacting rosin with epoxy compounds, and modified rosins having hydroxyl groups, such as polyethers with a rosin skeleton. These diols can be produced by conventional methods.

[0074] Examples of the rosin component include pimaric acid-type resin acids such as abietic acid and its derivatives, such as dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, neoabietic acid, and levopimaric acid; hydrogenated rosins obtained by hydrogenating these; and disproportionated rosins obtained by disproportionating these.

[0075] Among the above rosin-based resins, commercially available examples include 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, and Pine Crystal D-6250 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0076] Examples of the terpene resin include terpene phenolic resins. The terpene phenolic resin is a copolymer of phenol and a terpene resin, which is an essential oil component obtained from natural products such as rosin or orange peel. The copolymer also includes partially hydrogenated terpene phenolic resins obtained by at least partially hydrogenating the copolymer, and fully hydrogenated terpene phenolic resins. Here, fully hydrogenated terpene phenolic resins are terpene resins obtained by substantially completely hydrogenating a terpene phenolic resin, and partially hydrogenated terpene phenolic resins are terpene resins obtained by partially hydrogenating a terpene phenolic resin. The terpene phenolic resins have terpene-derived double bonds and aromatic ring double bonds derived from phenols. Therefore, fully hydrogenated terpene phenolic resins refer to resins in which both the terpene and phenolic moieties are completely or almost completely hydrogenated, while partially hydrogenated terpene phenolic resins refer to resins in which the degree of hydrogenation of these moieties is partial, rather than complete. The hydrogenation method and reaction format are not particularly limited. Among the above terpene phenol-based resins, commercially available examples include YS Polystar NH (fully hydrogenated terpene phenol-based resin) manufactured by Yasuhara Chemical Co., Ltd.

[0077] The content of the tackifier is preferably 5 parts by mass at the lower limit and 50 parts by mass at the upper limit, relative to 100 parts by mass of the total UV-curable pressure-sensitive adhesive composition not including the tackifier. By having the tackifier content within this range, the resulting UV-curable pressure-sensitive adhesive composition will have better adhesion to various substrates. The more preferred lower limit of the tackifier content is 10 parts by mass, and the more preferred upper limit is 35 parts by mass.

[0078] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention may contain a plasticizer, such as an organic acid ester, an organic phosphate ester, or an organic phosphite ester.

[0079] Examples of the organic acid esters include monobasic organic acid esters and polybasic organic acid esters. Examples of the monobasic organic acid esters include glycol esters obtained by reacting monobasic organic acids such as butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octylic acid, 2-ethylhexyl acid, pelargonic acid (n-nonylic acid), and decylic acid with glycols such as triethylene glycol, tetraethylene glycol, and tripropylene glycol. Examples of the polybasic organic acid esters include ester compounds obtained by reacting polybasic organic acids such as adipic acid, sebacic acid, and azelaic acid with alcohols having a linear or branched structure and 4 to 8 carbon atoms.

[0080] Specific examples of the organic acid ester include triethylene glycol di-2-ethylbutyrate (3GH), triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycol dicaprylate, triethylene glycol di-n-octanoate, and triethylene glycol di-n-heptanoate (3G7). Other examples include tetraethylene glycol di-n-heptanoate (4G7), tetraethylene glycol di-2-ethylhexanoate, dibutyl sebacate, dioctyl azelate, dibutyl carbitol adipate, ethylene glycol di-2-ethylbutyrate, and 1,3-propylene glycol di-2-ethylbutyrate. Further examples include 1,4-butylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate, and dipropylene glycol di-2-ethylbutyrate. Other examples include triethylene glycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate (4GH), diethylene glycol dicaprylate, dihexyl adipate (DHA), dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, etc. Other examples include oil-modified sebacic acid alkyd, a mixture of a phosphate ester and an adipate ester, and a mixed adipate ester prepared from an alkyl alcohol having 4 to 9 carbon atoms and a cyclic alcohol having 4 to 9 carbon atoms.

[0081] Examples of the organic phosphate ester or organic phosphite ester include compounds obtained by the condensation reaction between phosphoric acid or phosphorous acid and an alcohol. Of these, compounds obtained by the condensation reaction between an alcohol having 1 to 12 carbon atoms and phosphoric acid or phosphorous acid are preferred. Examples of the alcohol having 1 to 12 carbon atoms include methanol, ethanol, butanol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, and benzyl alcohol. Examples of the organic phosphate ester or organic phosphite ester include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tri(butoxyethyl) phosphate, tri(2-ethylhexyl) phosphite, isodecylphenyl phosphate, and triisopropyl phosphate.

[0082] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention may contain an antifoaming agent. Examples of the antifoaming agent include silicone-based antifoaming agents, acrylic polymer-based antifoaming agents, vinyl ether polymer-based antifoaming agents, and olefin polymer-based antifoaming agents.

[0083] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention may further contain various known additives such as a crosslinking agent, a viscosity modifier, a silane coupling agent, a sensitizer, a heat curing agent, a cure retarder, an antioxidant, a storage stabilizer, a dispersant, a filler, etc. From the viewpoint of preventing a decrease in ultraviolet reactivity, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention preferably does not substantially contain an organic solvent, and specifically, the content of the organic solvent is preferably 1.5 mass% or less relative to 100 mass% of the ultraviolet-curable pressure-sensitive adhesive composition.

[0084] A method for preparing the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 includes, for example, a method of using a mixer to mix the maleimide derivative, the ultraviolet-polymerizable compound, the photopolymerization initiator, the amine compound, and additives added as needed. A method for preparing the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 includes, for example, a method of using a mixer to mix the maleimide derivative, the ultraviolet-polymerizable compound, the photopolymerization initiator, and additives added as needed. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.

[0085] The ultraviolet-curable pressure-sensitive adhesive composition of the second invention is prepared by coating the ultraviolet-curable pressure-sensitive adhesive composition on a substrate, and then irradiating the coated surface with a wavelength of 365 nm and an illuminance of 20 mW / cm under atmospheric conditions without sealing the coated surface. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 can be prepared by simultaneously irradiating the ultraviolet-curable pressure-sensitive adhesive composition onto a substrate, and then irradiating the ultraviolet-curable pressure-sensitive adhesive composition onto the substrate at a wavelength of 365 nm and an illuminance of 20 mW / cm under atmospheric conditions without sealing the coated surface. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２It is preferable that the reactivity of a 100 μm-thick cured product obtained by simultaneously irradiating the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1 to the ultraviolet light source and the ultraviolet light source is 85% or more. When the reactivity of the cured product of the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1 is 85% or more, it can be said that the ultraviolet reactivity in the presence of oxygen is sufficiently high, making it possible to apply a method in which the ultraviolet-curable pressure-sensitive adhesive composition is printed into a desired shape and then laminated to an adherend. A more preferable lower limit of the reactivity of the cured product of the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1 is 88%. A PET film with a release-treated surface (release PET film) is preferably used as the substrate. The above conditions are such that the ultraviolet-curable pressure-sensitive adhesive composition is coated on the substrate, and then ultraviolet light is irradiated in the presence of oxygen without covering the coated surface with a separator. Therefore, the reactivity of the cured product reflects the ultraviolet reactivity in the presence of oxygen. In other words, due to the high reactivity of the cured product, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention has excellent adhesion in the presence of oxygen and low bleeding properties. The lower limit of the reaction rate of the cured product is preferably 90%, more preferably 92%. Although a higher reaction rate of the cured product is preferable, the practical upper limit is 99%.

[0086] Specifically, the reaction rate of the cured product can be measured, for example, according to the following procedure. First, the ultraviolet-curable pressure-sensitive adhesive composition is applied to a release PET film as a substrate. Then, using an ultraviolet irradiation device, the cured product is exposed to ultraviolet light at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２By simultaneously irradiating the ultraviolet rays so that the cured product is 100 μm thick, the ultraviolet-curable pressure-sensitive adhesive composition is cured, and a cured product with a thickness of 100 μm is obtained. Approximately 0.3 g of the obtained cured product is placed on an aluminum pan, and a mixed solvent containing THF:acetone:ethanol in an 8:1:1 mass ratio is gently added so as not to scatter the cured product sample, and the sample is allowed to swell for approximately 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 masses of the dried aluminum pan and the dried sample are then weighed, and the reaction rate of the cured product is calculated using the following formula: Reaction rate [%] = (Total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) x 100

[0087] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention is prepared by coating the ultraviolet-curable pressure-sensitive adhesive composition on a substrate and then irradiating the composition at a wavelength of 365 nm with an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The glass transition temperature of a 100 μm-thick cured product obtained by simultaneously irradiating the two layers at the same time is preferably −60° C. or higher and 20° C. or lower. When the glass transition temperature of the cured product is in this range, the product can have excellent adhesion to various substrates. The glass transition temperature is more preferably 10° C. or lower.

[0088] Specifically, the glass transition temperature of the cured product can be measured, for example, according to the following procedure: First, the ultraviolet-curable pressure-sensitive adhesive composition is applied to a release PET film as a substrate. Then, the composition is exposed to light at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The ultraviolet-curable pressure-sensitive adhesive composition is cured by simultaneously irradiating the ultraviolet rays so that the cured product has a thickness of 100 μm. The glass transition temperature can be determined from the tan δ peak temperature when dynamic viscoelasticity measurement is performed on the obtained cured product using a dynamic viscoelasticity measuring device under the following conditions. Examples of the dynamic viscoelasticity measuring device that can be used include the MCR-702e (manufactured by Anton Paar). <Conditions> Shear method: Measurement using an 8 mm parallel plate with a twin drive. Measurement temperature: -70 to 200°C. Heating rate: 7°C / min. Frequency: 1 Hz. While cooling from 50°C to -70°C at a rate of 10°C / min, the sample is pre-pressed with 8 N and measured from a low temperature as described below in (1) to (6). (1) The temperature is increased with a normal force of 20 N at a strain of 0.005%, and measurements are performed under these conditions until the torque value becomes less than 1500 μN m. (2) After (1), raise the temperature at a normal force of 8 N and a strain of 0.05%, and measure under these conditions until the torque value is less than 200 μN·m. (3) After (2), raise the temperature at a normal force of 3 N and a strain of 0.5%, and measure under these conditions until the torque value is less than 150 μN·m. If the torque in (3) is 150 μN·m or greater up to 120°C, proceed to (4). (4) After (3), raise the temperature at a normal force of 1.5 N and a strain of 2%, and measure under these conditions until the torque value is less than 100 μN·m. If the torque in (4) is 100 μN·m or greater up to 170°C, proceed to (5). (5) After (4), raise the temperature at a normal force of 1 N and a strain of 5%, and measure under these conditions until the torque value is less than 80 μN·m. If the torque in (5) is 80 μN·m or more up to 190°C or if the thickness becomes less than 30 μm, proceed to (6). (6) After (5), the temperature is raised to 10% strain with a normal force of 1 N, and measurements are taken under these conditions until the temperature reaches 200°C. If the thickness becomes less than 20 μm before the temperature in (6) reaches 200°C, the measurement is terminated.

[0089] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention is suitable for printing. Forming a pressure-sensitive adhesive layer by applying the composition in a desired pattern to an adherend (substrate) by printing has the advantage that the cutting process can be omitted compared to when a sheet-shaped pressure-sensitive adhesive is cut just before lamination to obtain a pressure-sensitive adhesive of the desired shape. As a result, it is possible to suppress the generation of waste and reduce the environmental load. Examples of methods for printing the ultraviolet-curable pressure-sensitive adhesive composition of the present invention include screen printing, inkjet printing, gravure printing, etc. Among these, screen printing is preferably used.

[0090] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention has a viscosity at 25°C of preferably 5 mPa·s at its lower limit and 100,000 mPa·s at its upper limit. Having a viscosity within this range makes the ultraviolet-curable pressure-sensitive adhesive composition of the present invention more suitable for printing. A more preferred lower limit of the viscosity is 10 mPa·s at its upper limit and 75,000 mPa·s at its upper limit. The viscosity can be measured, for example, using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer with an appropriate cone plate for each viscosity at 25°C and 10 rpm.

[0091] The ultraviolet-curable pressure-sensitive adhesive composition of the present invention forms an adhesive layer by curing it with ultraviolet light, and its use may involve forming an adhesive layer on a substrate (separator) to produce an adhesive sheet that can be transferred to an adherend, or may involve forming an adhesive layer directly on an adherend. The method of forming an adhesive layer directly on an adherend minimizes the number of bonding operations and prevents air bubbles from entering the interface during bonding. On the other hand, the method of forming an adhesive layer on a substrate (separator) has the advantage of fewer application constraints, since the adhesive layer is placed on the adherend by transfer.

[0092] The present invention also provides a method for producing a laminate, which includes a step of applying the ultraviolet-curable pressure-sensitive adhesive composition of the present invention onto a first adherend and exposing the composition to light to form an adhesive layer, and a step of attaching a second adherend onto the adhesive layer, wherein the method for applying the ultraviolet-curable pressure-sensitive adhesive composition is inkjet printing, screen printing, spray coating, spin coating, gravure offset, or reverse offset printing, and in which the ultraviolet-curable pressure-sensitive adhesive composition is partially applied onto the first adherend.

[0093] Examples of the material for the first adherend and the second adherend include metals such as stainless steel and aluminum, and resins.

[0094] The thickness of the adhesive layer is preferably 30 μm or more, more preferably 50 μm or more. By having the thickness of the adhesive layer be 30 μm or more, sufficient adhesion can be obtained. Furthermore, from the viewpoint of responding to the trend toward thinner electronic devices, the thickness of the adhesive layer is preferably 1000 μm or less, more preferably 500 μm or less.

[0095] According to the present invention, it is possible to provide an ultraviolet-curable pressure-sensitive adhesive composition that has excellent printability, is resistant to cohesive failure in a cured product, and has excellent impact resistance, and an ultraviolet-curable pressure-sensitive adhesive composition that has excellent adhesion and low bleeding properties. Furthermore, according to the present invention, it is possible to provide a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0097] (Examples 1-1 to 1-40, Comparative Examples 1-1 to 1-17) Each material was mixed in a planetary mixer (Thinky Corporation, "Awatori Rentaro") according to the blending ratios shown in Tables 1 to 6 to obtain each of the PSA compositions of Examples 1-1 to 1-40 and Comparative Examples 1-1 to 1-17. Details of the materials listed by abbreviations in the tables are as follows. (Maleimide derivatives) CHMI: N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd., no structure in which hydrogen is bonded to a heteroatom) LMI: N-laurylmaleimide (manufactured by Seiko Chemical Industry Co., Ltd., no structure in which hydrogen is bonded to a heteroatom) HPM: 4-hydroxyphenylmaleimide (manufactured by Seiko Chemical Industry Co., Ltd., structure in which hydrogen is bonded to a heteroatom) (UV-polymerizable compounds) CBA: ethyl carbitol acrylate (manufactured by Osaka Organic Chemical Industry Ltd., "Viscoat #190", contains an ether bond) MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd., contains an ether bond) Viscoat #192: phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd., contains a phenoxy group) Viscoat #216: acrylic acid-2-butylcarbamoyloxyethyl ester (manufactured by Osaka Organic Chemical Industry Ltd., containing an amide bond) NOAA: n-octyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) 4-HBA: 4-hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation) UA-160TM: polyether-based multifunctional urethane acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) NVC: N-vinyl-ε-caprolactam (manufactured by Tokyo Chemical Industry Co., Ltd.) (photopolymerization initiator) Esacure TZT: mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (manufactured by IGM Resins, hydrogen abstraction photopolymerization initiator) Omnirad 4MBZ: 4-methylbenzophenone (manufactured by IGM Resins, hydrogen abstraction photopolymerization initiator) Omnipol TP: Ethyl (2,4,6-trimethylbenzoyl)-phenylphosphineate polymer (manufactured by IGM Resins, polymer type photopolymerization initiator) Omnipol 910: polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate (manufactured by IGM Resins, polymer type photopolymerization initiator) Omnipol 2702: bis(benzophenone-2-carboxylic acid) polyethylene glycol ester (manufactured by IGM Resins, polymer type photopolymerization initiator) Omnirad 184: 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins, cleavage type photopolymerization initiator) Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins, cleavage type photopolymerization initiator) Omnirad 819: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins, cleavage-type photopolymerization initiator) (amine compound) Esacure A198: (bis-N,N-(4-dimethylaminobenzoyl)oxyethylene-1-yl)-methylamine, bis(2-morpholinoethyl)ether (manufactured by IGM Resins, no structure in which hydrogen is bonded to a heteroatom) U-cat 660M: bis(2-morpholinoethyl)ether (manufactured by San-Apro, no structure in which hydrogen is bonded to a heteroatom) Eversorb 93: 1-methyl 10-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate (manufactured by Everlight Chemical, no structure in which hydrogen is bonded to a heteroatom) ADK STAB LA-72: bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (manufactured by ADEKA Corporation, no structure with hydrogen bonded to a heteroatom) ADK STAB LA-52: tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (manufactured by ADEKA Corporation, no structure with hydrogen bonded to a heteroatom) ADK STAB LA-77Y: bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (manufactured by ADEKA Corporation, structure with hydrogen bonded to a heteroatom) ADK STAB LA-57: tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-Tetracarboxylate (manufactured by ADEKA Corporation, has a structure in which hydrogen is bonded to a hetero atom) (tackifier) ​​KE-359: rosin-based resin (manufactured by Arakawa Chemical Industries, Ltd.) (thermoplastic resin) LA2140: acrylic block copolymer (manufactured by Kuraray Co., Ltd.) LA4285: acrylic block copolymer (manufactured by Kuraray Co., Ltd.) (crosslinking agent) Coronate L: toluene diisocyanate (manufactured by Tosoh Corporation)

[0098] (Reaction rate of cured product) The obtained pressure-sensitive adhesive composition was coated on a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) by the method shown below to obtain a cured product having a thickness of 100 μm. For each of the pressure-sensitive adhesive compositions obtained in Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12, 0.5 mL of each pressure-sensitive adhesive composition was dropped onto a release PET film and coated for 10 seconds at 5000 rpm using a spin coater (manufactured by Mikasa Corporation, "MSB-150") to produce a thin layer. Next, in an atmospheric environment without sealing the top surface of the coating, a batch-type UV LED curing device (manufactured by ITEC Corporation, "M UVBA") was used to cure the cured product at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The adhesive compositions were simultaneously irradiated so that the thickness of the cured product reached 100 μm. This process was repeated until the thickness of the cured product reached 100 μm. For each of the pressure-sensitive adhesive compositions obtained in Examples 1-36 to 1-39 and Comparative Examples 1-13 and 1-14, a screen printing machine ("SSA-PC560E" manufactured by SERIA) was used to apply the pressure-sensitive adhesive composition to a release PET film to a thickness of 100 μm. Thereafter, the upper surface of the coating was not sealed, and the cured product was exposed to light at a wavelength of 365 nm and an illuminance of 20 mW / cm using a batch-type UV LED curing device in an atmospheric environment. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The pressure-sensitive adhesive composition was cured by simultaneously irradiating the two films so that the thickness was 100 μm, thereby obtaining a cured product with a thickness of 100 μm. As the batch-type UV LED curing device, an M UVBA (manufactured by ITEC Co., Ltd.) was used. The pressure-sensitive adhesive composition obtained in Comparative Example 1-15 was applied to a release-treated PET film using a coater so that the thickness after drying would be 100 μm, and then dried at 80°C for 1 hour and at 110°C for 20 minutes to obtain a cured product. For each of the pressure-sensitive adhesive compositions obtained in Comparative Examples 1-16 and 1-17, the pressure-sensitive adhesive composition was applied to a release PET film using an applicator, and the coated surface was sealed with a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) to obtain a UVWet laminated coating. The obtained UVWet laminated coated product was cured using a batch-type UV LED curing device at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The adhesive composition was cured by simultaneous irradiation so that the temperature reached 100°C, yielding a cured product with a thickness of 100 μm. The batch-type UV LED curing device used was an M UVBA (manufactured by ITEC Co., Ltd.). Approximately 0.3 g of the resulting cured product was placed on an aluminum pan, and a mixed solvent containing THF:acetone:ethanol in an 8:1:1 mass ratio was gently added to prevent the cured product sample from scattering. The sample was then allowed to swell for approximately 2 hours. The sample was then dried at 110°C for 30 minutes, 170°C for 1 hour, and 190°C for 30 minutes. The masses of the aluminum pan and the dried sample after drying were weighed, and the reaction rate of the cured product was calculated using the following formula: Reaction rate [%] = (total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) x 100 The reaction rates of the cured products of the pressure-sensitive adhesive compositions obtained in Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12 correspond to the reaction rates of the cured products of the pressure-sensitive adhesive compositions applied by inkjet printing.

[0099] (Glass Transition Temperature of Cured Product) For a cured product obtained in the same manner as in "(Reaction Rate of Cured Product)" above, dynamic viscoelasticity measurement was performed under the following conditions using a dynamic viscoelasticity measuring device ("MCR-702e" manufactured by Anton Paar), and the tan δ peak temperature was determined as the glass transition temperature. <Conditions> Shear method: Measurement using an 8 mm parallel plate with a twin drive. Measurement temperature: -70 to 200°C. Heating rate: 7°C / min. Frequency: 1 Hz. While cooling from 50°C to -70°C at a rate of 10°C / min, the sample was pre-pressed with 8N and measured from a low temperature as described in (1) to (6) below. (1) The sample was heated at a normal force of 20N with a strain of 0.005%, and measurements were made under these conditions until the torque value reached less than 1500 μN m. (2) After (1), the sample was heated at a normal force of 8N with a strain of 0.05%, and measurements were made under these conditions until the torque value reached less than 200 μN m. (3) After (2), raise the temperature with a normal force of 3 N and a strain of 0.5%, and measure under these conditions until the torque value is less than 150 μN·m. If the torque in (3) is 150 μN·m or greater up to 120°C, proceed to (4). (4) After (3), raise the temperature with a normal force of 1.5 N and a strain of 2%, and measure under these conditions until the torque value is less than 100 μN·m. If the torque in (4) is 100 μN·m or greater up to 170°C, proceed to (5). (5) After (4), raise the temperature with a normal force of 1 N and a strain of 5%, and measure under these conditions until the torque value is less than 80 μN·m. If the torque in (5) is 80 μN·m or greater up to 190°C or the thickness is less than 30 μm, proceed to (6). (6) After (5), the temperature is raised with a normal force of 1 N and a strain of 10%, and measurements are taken under these conditions until the temperature reaches 200° C. If the thickness becomes less than 20 μm before the temperature in (6) reaches 200° C., the measurement is terminated.

[0100] <Evaluation> The pressure-sensitive adhesive compositions obtained in Examples 1-1 to 1-40 and Comparative Examples 1-1 to 1-17 were evaluated as follows. The results are shown in Tables 1 to 6.

[0101] (Printability) 0.5 mL of each of the pressure-sensitive adhesive compositions obtained in Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12 was dropped onto a 50 mm x 50 mm aluminum substrate, and coated using a spin coater (manufactured by Mikasa Co., Ltd., "MSB-150") at 5,000 rpm for 10 seconds to prepare a thin layer. Next, using a batch-type UV LED curing device (manufactured by ITEC Co., Ltd., "M UVBA"), the resulting layer was cured with a UV LED at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The layers were simultaneously irradiated so that the thickness of the cured product reached 100 μm. This process was repeated until the thickness of the cured product reached 100 μm. Furthermore, 1 part by mass of KS-66 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as an antifoaming agent to 100 parts by mass of each of the pressure-sensitive adhesive compositions obtained in Examples 1-36 to 1-39 and Comparative Examples 1-13 and 1-14 to obtain screen-printable compositions. The obtained screen-printable compositions were pattern-coated on a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) using a screen printer (manufactured by SERIA Corporation, "SSA-PC560E") to perform screen printing. A pattern-treated 70-mesh printing plate was used as the screen printing plate. Next, a batch-type UV LED curing device (manufactured by ITEC Corporation, "M UVBA") was used to apply a pattern of 70-mesh UV light at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ Cured products were obtained by simultaneously irradiating the ink with light so that the cured product was 100%. Each of the obtained cured products was visually inspected, and printability was evaluated according to the following criteria. In Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12, spin coating was performed as an alternative to inkjet printing, and the printability of each pressure-sensitive adhesive composition obtained in Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12 corresponds to the printability in inkjet printing. ○: When there were no uncured areas and no bleeding was observed ×: When there were uncured areas, or when there were no uncured areas but bleeding was observed

[0102] (Adhesive Strength and Peeling Mode) (1) Preparation of Test Pieces (1-1) Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12 For each of the pressure-sensitive adhesive compositions obtained in Examples 1-1 to 1-35, 1-40, and Comparative Examples 1-1 to 1-12, 0.5 mL of each pressure-sensitive adhesive composition was dropped onto a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm), and coated using a spin coater at 5000 rpm for 10 seconds to prepare a thin layer having a width of 50 mm and a length of 50 mm. The spin coater used was an MSB-150 (manufactured by Mikasa Corporation). Thereafter, a batch-type UV LED curing device (manufactured by ITEC Corporation, "M UVBA") was used to cure the adhesive composition at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The film was cured by simultaneous irradiation so that the temperature was 100 μm. This process was repeated to obtain a cured product with a thickness of 100 μm. Next, the air side of the cured product was sealed with a highly adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") having a width of 50 mm and a length of 200 mm, and the film was cut to a width of 25 mm and a length of 200 mm (adhesion surface 20 mm × 50 mm) to produce a laminated film. Thereafter, the release PET film was peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving it back and forth with a 2 kg roller to obtain a test piece. (1-2) Examples 1-36 to 1-39 and Comparative Examples 1-13 and 1-14 For each of the pressure-sensitive adhesive compositions obtained in Examples 1-36 to 1-39 and Comparative Examples 1-13 and 1-14, a screen printing machine (SERIA, "SSA-PC560E") was used to apply the pressure-sensitive adhesive composition to a thickness of 100 μm on a highly adhesive polyester film (Toyobo, "Cosmoshine A4100"). Thereafter, a batch-type UV LED curing device (ITEC, "M UVBA") was used to apply the composition to a substrate at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The pressure-sensitive adhesive composition was cured by simultaneous irradiation so that a cured product with a thickness of 100 μm was obtained. Next, the air side of the cured product was sealed with a release PET film (Nippa Corporation, "1-E", thickness 50 μm), and the cured product was cut to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 80 mm) to produce a laminated film. Thereafter, the release PET film was peeled from the laminated film, and the exposed surface was attached to a SUS substrate and pressure-bonded by moving it back and forth with a 2 kg roller to obtain a test piece. (1-3) Comparative Example 1-15 For the pressure-sensitive adhesive composition obtained in Comparative Example 1-15, the pressure-sensitive adhesive composition was applied to a highly adhesive polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") using a coater so that the thickness after drying would be 100 μm, and the composition was dried at 80 ° C for 1 hour and at 110 ° C for 20 minutes to obtain a cured product. Next, the air surface of the cured product was sealed with a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm), and the film was cut to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 80 mm) to prepare a laminated film. Thereafter, the release PET film was peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving it back and forth with a 2 kg roller to obtain a test specimen. (1-4) Comparative Examples 1-16 and 1-17 For each of the pressure-sensitive adhesive compositions obtained in Comparative Examples 1-16 and 1-17, the pressure-sensitive adhesive composition was applied to a highly adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") using an applicator, and the coated upper surface was sealed with a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) to form a UVWet laminated coating. The obtained UVWet laminated coating was cured using a batch-type UV LED curing device with a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The adhesive composition was cured by simultaneous irradiation so that a cured product with a thickness of 100 μm was obtained. The batch-type UV LED curing device used was an M UVBA (manufactured by ITEC Co., Ltd.). Next, a laminated film was produced by cutting it to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 80 mm). The release PET film was then peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed back and forth with a 2 kg roller to obtain a test specimen.

[0103] (2) Measurement of adhesive strength and confirmation of peeling mode After aging the obtained test pieces for one day in an environment of 25°C and 50% RH, adhesive strength was measured by performing a 180° peel at a speed of 300 mm / min using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310"). The peeling mode during 180° peeling was evaluated according to the following criteria: AF: Interfacial peeling WLB: Near-interface cohesive peeling Zip: Zipping peeling CF: Cohesive failure Note that AF and WLB are favorable results, Zip is an inferior result, and CF is an even worse result.

[0104] (Impact Resistance) For the cured product obtained in the same manner as in "(Reaction Rate of Cured Product)" above, an impact resistance test was carried out by the following method. A 40 mm x 40 mm x 3 mm SUS substrate with a 20 mm x 20 mm x 3 mm hole in the center and a 25 mm x 25 mm x 3 mm SUS substrate were bonded together via a 25 mm x 25 mm x 3 mm SUS substrate to obtain a laminate. The obtained laminate was pressure-bonded at 62 N using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310") to prepare a test piece. Using a drop weight impact tester (manufactured by IMATEK Co., Ltd., "IM1C-15 Model"), a drop weight of 16 Φ and a total mass of 5 kg was dropped naturally from a height of 51 mm to impact the center of the test piece. ms v. s. From the N spectrum, the area (amount of energy) of the first peak was taken as the impact absorption rate ΔE [J], and the peak force (impact resistance test force [N]) was calculated. Impact resistance was evaluated according to the following criteria: ◎: When ΔE exceeded 0.3 J or when the peak force exceeded 1.4 N ○: When ΔE was 0.15 J or more and 0.3 J or less, and the peak force was 0.8 N or more and 1.4 N or less ×: When ΔE was less than 0.15 J, and the peak force was 0.8 N or more and 1.4 N or less xx: When ΔE was less than 0.15 J, and the peak force was less than 0.8 N

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] (Examples 2-1 to 2-20, Comparative Examples 2-1 to 2-3) Each material was mixed in a planetary mixer (Thinky Corporation, "Awatori Rentaro") according to the blending ratios shown in Tables 7 to 9 to obtain each of the PSA compositions of Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-3. Details of the materials listed by abbreviations in the tables are as follows. (Maleimide derivatives) CHMI: N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd.) HPM: 4-hydroxyphenylmaleimide (manufactured by Seiko Chemical Industry Co., Ltd.) NCCHMI: N-(4-carboxycyclohexylmethyl)maleimide (manufactured by Seiko Chemical Industry Co., Ltd.) (UV-polymerizable compounds) CBA: ethyl carbitol acrylate (manufactured by Osaka Organic Chemical Industry Ltd., "Viscoat #190", containing an ether bond) MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd., containing an ether bond) Viscoat #192: phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd., containing a phenoxy group) Viscoat #216: acrylic acid-2-butylcarbamoyloxyethyl ester (manufactured by Osaka Organic Chemical Industry Ltd., containing an amide bond) NOAA: n-octyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 4-HBA: 4-hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation) UA-160TM: polyether-based multifunctional urethane acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) NVC: N-vinyl-ε-caprolactam (manufactured by Tokyo Chemical Industry Co., Ltd.) (photopolymerization initiator) Omnirad 184: 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins, cleavage-type photopolymerization initiator) Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins, cleavage-type photopolymerization initiator) Omnirad 819: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins, cleavage-type photopolymerization initiator) Esacure 1001M: 1-(4-(4-benzoylphenylthio)phenyl)-2-tosyl-2-methyl-1-propanone (manufactured by IGM Resins, hydrogen abstraction-type photopolymerization initiator) Esacure 3644: 3-ketocoumarin (manufactured by IGM Resins, hydrogen abstraction-type photopolymerization initiator) (amine compounds) Esacure A198: (bis-N,N-(4-dimethylaminobenzoyl)oxyethylene-1-yl)-methylamine, bis(2-morpholinoethyl)ether (manufactured by IGM Resins) U-cat 660M: bis(2-morpholinoethyl)ether (manufactured by San-Apro Co., Ltd.) (tackifier) KE-359: rosin-based resin (manufactured by Arakawa Chemical Industries, Ltd.) (thermoplastic resin) LA2140: acrylic block copolymer (manufactured by Kuraray Co., Ltd.)

[0112] The acrylic polymer used as the thermoplastic resin in Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-3 was prepared by the following method. 100 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 300 parts by mass of ethyl acetate as a polymerization solvent were added to a 2-L separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a condenser. Next, nitrogen gas was blown into the reaction vessel for 30 minutes to replace the atmosphere with nitrogen, and the reaction vessel was heated to 80°C with stirring. After 30 minutes, 0.5 parts by mass of t-butylperoxy-2-ethylhexanoate (1-hour half-life temperature: 92.1°C, 10-hour half-life temperature: 72.1°C) as a polymerization initiator was diluted with 5 parts by mass of ethyl acetate, and the resulting polymerization initiator solution was added dropwise to the reaction vessel over 6 hours. The mixture was then allowed to react for an additional 6 hours at 80°C, and the reaction solution was cooled to obtain an acrylic polymer solution. The resulting acrylic polymer solution was diluted with a dilution solvent (a mixed solvent of methanol and toluene, with a mass ratio of methanol to toluene of 1:2) to obtain a solution with a solids content of 20 mass %. This solution was then applied to a release-treated PET film using a coater to a dry thickness of 100 μm, and dried at 80° C. for 1 hour and at 110° C. for 20 minutes to obtain an acrylic polymer.

[0113] (Viscosity) 0.4 mL of the obtained pressure-sensitive adhesive composition was sampled, and the viscosity was measured using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer with an appropriate cone plate for each viscosity at 25° C. and 10 rpm.

[0114] (Reaction rate of cured product) The obtained pressure-sensitive adhesive composition was coated on a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) by the method shown below to obtain a cured product having a thickness of 100 μm. For each of the pressure-sensitive adhesive compositions obtained in Examples 2-1 to 2-14, 2-16 to 2-20, and Comparative Examples 2-1 to 2-3, the pressure-sensitive adhesive composition was coated on a release PET film to a thickness of 100 μm using a screen printing machine (manufactured by SERIA, "SSA-PC560E"). Thereafter, the upper surface of the coating was not sealed, and the cured product was cured in an atmospheric environment using a batch-type UV LED curing device with a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The pressure-sensitive adhesive composition was cured by simultaneously irradiating the two components so that the cured product had a thickness of 100 μm, thereby obtaining a cured product. As the batch-type UV LED curing device, an M UVBA (manufactured by ITEC Co., Ltd.) was used. For the pressure-sensitive adhesive composition obtained in Example 2-15, 0.5 mL of the pressure-sensitive adhesive composition was dropped onto a release PET film, and coated for 10 seconds at 5,000 rpm using a spin coater (manufactured by Mikasa Co., Ltd., "MSB-150") to produce a thin layer. Next, in an atmospheric environment without sealing the top surface of the coating, a batch-type UV LED curing device (manufactured by ITEC Co., Ltd., "M UVBA") was used to cure the pressure-sensitive adhesive composition at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The samples were simultaneously irradiated so that the cured product reached a thickness of 100 μm. This process was repeated until the thickness of the cured product reached 100 μm. Approximately 0.3 g of the obtained cured product was placed on an aluminum pan, and a mixed solvent containing THF:acetone:ethanol in an 8:1:1 mass ratio was gently added to prevent the cured product sample from scattering. The sample was allowed to swell for approximately 2 hours. The sample was then dried at 110°C for 30 minutes, 170°C for 1 hour, and 190°C for 30 minutes. The masses of the dried aluminum pan and the dried sample were weighed, and the reaction rate of the cured product was calculated using the following formula: Reaction rate [%] = (Total mass of aluminum pan and sample after drying - Mass of aluminum pan before drying) / (Mass of sample before swelling) x 100. Note that in Example 2-15, spin coating was used instead of inkjet printing, and the reaction rate of the cured product of the adhesive composition obtained in Example 2-15 corresponds to the reaction rate of the cured product of the adhesive composition coated by inkjet printing.

[0115] (Glass Transition Temperature of Cured Product) For a cured product obtained in the same manner as in "(Reaction Rate of Cured Product)" above, dynamic viscoelasticity measurement was performed under the following conditions using a dynamic viscoelasticity measuring device ("MCR-702e" manufactured by Anton Paar), and the tan δ peak temperature was determined as the glass transition temperature. <Conditions> Shear method: Measurement using an 8 mm parallel plate with a twin drive. Measurement temperature: -70 to 200°C. Heating rate: 7°C / min. Frequency: 1 Hz. While cooling from 50°C to -70°C at a rate of 10°C / min, the sample was pre-pressed with 8N and measured from a low temperature as described in (1) to (6) below. (1) The sample was heated at a normal force of 20N with a strain of 0.005%, and measurements were made under these conditions until the torque value reached less than 1500 μN m. (2) After (1), the sample was heated at a normal force of 8N with a strain of 0.05%, and measurements were made under these conditions until the torque value reached less than 200 μN m. (3) After (2), raise the temperature with a normal force of 3 N and a strain of 0.5%, and measure under these conditions until the torque value is less than 150 μN·m. If the torque value in (3) is 150 μN·m or greater up to 120°C, proceed to (4). (4) After (3), raise the temperature with a normal force of 1.5 N and a strain of 2%, and measure under these conditions until the torque value is less than 100 μN·m. If the torque value in (4) is 100 μN·m or greater up to 170°C, proceed to (5). (5) After (4), raise the temperature with a normal force of 1 N and a strain of 5%, and measure under these conditions until the torque value is less than 80 μN·m. If the torque value in (5) is 80 μN·m or greater up to 190°C or the thickness is less than 30 μm, proceed to (6). (6) After (5), the temperature is raised with a normal force of 1 N and a strain of 10%, and measurements are taken under these conditions until the temperature reaches 200° C. If the thickness becomes less than 20 μm before the temperature in (6) reaches 200° C., the measurement is terminated.

[0116] <Evaluation> The pressure-sensitive adhesive compositions obtained in Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-3 were evaluated as follows. The results are shown in Tables 7 to 9.

[0117] (Adhesion (Open) and Peeling Mode) (1) Preparation of Test Pieces (1-1) Examples 2-1 to 2-14, 2-16 to 2-20, and Comparative Examples 2-1 to 2-3 For each of the pressure-sensitive adhesive compositions obtained in Examples 2-1 to 2-14, 2-16 to 2-20, and Comparative Examples 2-1 to 2-3, the pressure-sensitive adhesive composition was applied to a highly adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") using a screen printing machine to a thickness of 100 μm, a width of 25 mm, and a length of 80 mm. The screen printing machine used was an SSA-PC560E (manufactured by SERIA). Thereafter, the upper surface of the coating was cured in an atmospheric environment without sealing, using a batch-type UV LED curing device, with a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The pressure-sensitive adhesive composition was cured by simultaneous irradiation so that a cured product with a thickness of 100 μm was obtained. The batch-type UV LED curing device used was an M UVBA (manufactured by ITEC Co., Ltd.). Next, the air side of the cured product was sealed with a release PET film (manufactured by Nippa Co., Ltd., "1-E", thickness 50 μm), and the film was cut to a width of 25 mm and a length of 200 mm to produce 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 back and forth with a 2 kg roller to obtain a test specimen. (1-2) Example 2-15 For each of the pressure-sensitive adhesive compositions obtained in Example 2-15, 0.5 mL of each pressure-sensitive adhesive composition was dropped onto a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm), and coated using a spin coater (manufactured by Mikasa Corporation, "MSB-150") at 5000 rpm for 10 seconds to prepare a thin layer having a width of 50 mm and a length of 50 mm. Thereafter, using a batch-type UV LED curing device (manufactured by ITEC Corporation, "M UVBA"), the composition was cured at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２The film was cured by simultaneous irradiation so that the temperature was 100 μm. This process was repeated to obtain a cured product with a thickness of 100 μm. Next, the air side of the cured product was sealed with a highly adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") having a width of 50 mm and a length of 200 mm, and the film was cut to a width of 25 mm and a length of 200 mm (adhesion surface 20 mm × 50 mm) to produce a laminated film. Thereafter, the release PET film was peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving it back and forth with a 2 kg roller to obtain a test piece.

[0118] (2) Measurement of adhesive strength and confirmation of peeling mode After aging the obtained test piece for one day in an environment of 25°C and 50% RH, the adhesive strength (Open) was measured by performing a 180° peel at a speed of 300 mm / min using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310"). The peeling mode during 180° peeling was evaluated according to the following criteria: AF: Interfacial peeling WLB: Near-interface cohesive peeling Zip: Zipping peeling CF: Cohesive failure Note that AF and WLB are favorable results, Zip is an inferior result, and CF is an even worse result.

[0119] (Adhesion (Close) and Adhesion Ratio) The adhesion (Close) was measured as a reference for comparison with the above-mentioned adhesion (Open). For compositions in which the components other than the photopolymerization initiator were the same as those in Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-3, 0.5 parts by mass each of Omnirad 184, Omnirad TPO, and Omnirad 819 was added to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound, and the mixture was mixed using a planetary mixer to obtain a pressure-sensitive adhesive composition. Awatori Rentaro (manufactured by Thinky Corporation) was used as the planetary mixer. Each of the obtained pressure-sensitive adhesive compositions was coated onto a highly adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") to a thickness of 100 μm using a screen printing machine (manufactured by SERIA, "SSA-PC560E"). Thereafter, the upper surface of the coating (air surface) was sealed with a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm). Next, using a batch-type UV LED curing device, the coating was cured with light having a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ The total irradiation amount is 900 mJ / cm ２ The adhesive composition was cured by simultaneous irradiation so that a cured product with a thickness of 100 μm was obtained. An M UVBA (manufactured by ITEC Co., Ltd.) was used as the batch-type UV LED curing device. Next, the resulting laminate of the highly adhesive polyester film, the cured product, and the release PET film was cut to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 80 mm) to produce a laminate film. The release PET film was then peeled from the laminate film, and the exposed surface was attached to a SUS substrate and pressed with a 2 kg roller back and forth to obtain a test specimen. The resulting test specimen was aged for one day in an environment of 25 °C and 50% RH, and then the adhesive strength (Close) was measured by performing a 180° peel at a speed of 300 mm / min using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310"). In addition, the adhesive strength ratio was calculated as (adhesive strength (open) / adhesive strength (close))×100.

[0120] (Low Bleeding) For a cured product obtained in the same manner as in "(Reaction rate of cured product)" above, five lines about 1 cm long were drawn on the surface with an oil-based marker (Zebra's "Makie") at intervals of about 2 mm, and the state of each line was visually observed. The low bleeding was evaluated according to the following criteria. ○: When all five lines were drawn without fading △: When all five lines were drawn, but fading was observed in one or more lines ×: When one or more lines could not be drawn

[0121]

[0122]

[0123]

[0124] According to the present invention, it is possible to provide an ultraviolet-curable pressure-sensitive adhesive composition that has excellent printability, is resistant to cohesive failure in a cured product, and has excellent impact resistance, and an ultraviolet-curable pressure-sensitive adhesive composition that has excellent adhesion and low bleeding properties. Furthermore, according to the present invention, it is possible to provide a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.

Claims

1. This is an ultraviolet-curable adhesive composition containing a maleimide derivative, an ultraviolet polymerizable compound, a photopolymerization initiator, and an amine compound. If the maleimide derivative includes a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom, then it does not include a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom, or the content of a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom in the maleimide derivative is less than 50% by mass. If the maleimide derivative comprises only maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom, then the content of the maleimide derivative having a structure in which hydrogen is bonded to a heteroatom is 9.8 parts by mass or less per 100 parts by mass of the ultraviolet polymerizable compound. The UV polymerizable compound contains 20% by mass or more of a monomer that can act as a hydrogen donor. The photopolymerization initiator comprises at least one selected from the group consisting of hydrogen abstraction type photopolymerization initiators and polymer type photopolymerization initiators. The amine compound contains 50% by mass or more of an amine compound that does not have a structure in which hydrogen is bonded to a heteroatom in the amine compound. The content of the amine compound is 0.1 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total of the maleimide derivative and the UV polymerizable compound. A UV-curable adhesive composition characterized by the following features.

2. The ultraviolet-curable adhesive composition according to claim 1, wherein the content of the maleimide derivative per 100 parts by mass of the ultraviolet polymerizable compound is 0.1 parts by mass or more and 20 parts by mass or less.

3. The ultraviolet-curable adhesive composition according to claim 1 or 2, wherein the monomer that can serve as the hydrogen donor is a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.

4. The UV-curable adhesive composition is applied to a substrate, and the coated surface is not sealed. In an atmospheric environment, the temperature is measured at a wavelength of 365 nm and an illuminance of 20 mW / cm². ２ Ultraviolet light, with a wavelength of 405 nm and an illuminance of 40 mW / cm². ２ The light emitted was 900 mJ / cm². ２ The ultraviolet-curable adhesive composition according to claim 1 or 2, wherein the reaction rate of a cured product with a thickness of 100 μm obtained by simultaneous irradiation in such a manner is 85% or more.

5. This is an ultraviolet-curable adhesive composition containing a maleimide derivative, an ultraviolet polymerizable compound, and a photopolymerization initiator. Furthermore, it contains amine compounds, The content of the maleimide derivative is 8 parts by mass or more per 100 parts by mass of the UV polymerizable compound. The UV-curable adhesive composition is applied to a substrate, and the coated surface is not sealed. In an atmospheric environment, the temperature is measured at a wavelength of 365 nm and an illuminance of 20 mW / cm². ２ Ultraviolet light, with a wavelength of 405 nm and an illuminance of 40 mW / cm². ２ The light emitted was 900 mJ / cm². ２ The reaction rate of the cured material with a thickness of 100 μm obtained by simultaneous irradiation in such a manner is 88% or higher. A UV-curable adhesive composition characterized by the following features.

6. The ultraviolet-curable adhesive composition according to claim 1, 2, or 5, comprising 50% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond, wherein the ultraviolet-polymerizable compound is further comprising 50% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.

7. The ultraviolet-curable adhesive composition according to claim 1, 2, or 5, comprising at least one ultraviolet polymerizable compound selected from the group consisting of (meth)acrylic monomers and vinyl monomers.

8. The ultraviolet-curable adhesive composition according to claim 7, comprising a polyfunctional (meth)acrylic monomer as the ultraviolet polymerizable compound.

9. The UV-curable adhesive composition according to claim 8, wherein the content of the polyfunctional (meth)acrylic monomer is 25 parts by mass or less relative to 100 parts by mass of the total of the maleimide derivative and the UV-polymerizable compound excluding the polyfunctional (meth)acrylic monomer.

10. The ultraviolet-curable adhesive composition according to claim 9, wherein the content of the polyfunctional (meth)acrylic monomer is 20 parts by mass or less relative to 100 parts by mass of the total of the maleimide derivative and the ultraviolet polymerizable compound excluding the polyfunctional (meth)acrylic monomer.

11. The ultraviolet-curable adhesive composition according to claim 1, 2, or 5, wherein the content of the photopolymerization initiator is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total of the maleimide derivative and the ultraviolet-polymerizable compound.

12. Furthermore, the ultraviolet-curable adhesive composition according to claim 1, 2, or 5, further containing a thermoplastic resin.

13. Furthermore, the ultraviolet-curable adhesive composition according to claim 1, 2, or 5, further containing a tackifier.

14. The ultraviolet-curable adhesive composition according to claim 1, 2, or 5, wherein the viscosity at 25°C is 10 mPa·s or more and 75,000 mPa·s or less.

15. The ultraviolet-curable adhesive composition is applied onto a substrate, and ultraviolet light with a wavelength of 365 nm and an illuminance of 20 mW / cm ２ and light with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ are simultaneously irradiated so that the total irradiation dose is 900 mJ / cm ２ The ultraviolet-curable adhesive composition according to claim 1, 2 or 5, wherein the glass transition temperature of the cured product with a thickness of 100 μm obtained by the simultaneous irradiation is -60°C or higher and 20°C or lower.

16. The method comprises the steps of applying the ultraviolet-curable adhesive composition according to claim 1, 2, or 5 onto a first adherend and exposing it to light to form an adhesive layer, and attaching a second adherend onto the adhesive layer. A method for coating the ultraviolet-curable adhesive composition is inkjet printing, screen printing, spray coating, spin coating, gravure offset, or reverse offset printing, and a method for manufacturing a laminate in which the ultraviolet-curable adhesive composition is partially coated on the first adherend.