Active energy ray-curable adhesive and laminate

Abstract

To provide an active energy ray-curable adhesive having good adhesive force to plastic substrates with each other, inorganic substrates such as glass and metal with each other, and further different kinds of substrates, and having high transparency, excellent coating suitability, and excellent long-term moisture and heat resistance.SOLUTION: The active energy ray-curable adhesive contains a polyetherurethane (meth) acrylate compound (A) having a specific structure, a (meth) acrylate compound (B) (excluding the compound (A)), and a photopolymerization initiator (C), wherein the (meth) acrylate compound (B) contains a (meth) acrylate compound (b1) whose homopolymer has a glass-transition temperature of 50 °C or higher. The active energy ray-curable adhesive is characterized in that the content of the (meth) acrylate compound (b1) is 20 mass% or more with respect to 100 mass% of the (meth) acrylate compound (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable adhesive and a laminate using the same. [Background technology]

[0002] Active energy ray curable adhesives have long been studied, including ultraviolet ray curable adhesives (UV adhesives) (see Non-Patent Document 1).

[0003] UV adhesives harden through polymerization and crosslinking reactions to develop adhesive properties (adhesive function). The method by which adhesion is initiated is unique. Specifically, when UV light is irradiated (the UV light acts as a trigger), a phase change from liquid to solid occurs through a chain reaction of photopolymerization, resulting in bonding (see Non-Patent Document 1).

[0004] Active energy ray-curable adhesives for use with plastic materials and the like often contain urethane-based monomers, oligomers, and polymers as components (see Patent Documents 1 to 8). Patent Documents 1 and 2 disclose curable resin compositions containing a urethane (meth)acrylate resin as a polymerizable oligomer or polymer, and Patent Document 3 also discloses an active energy ray-curable resin composition having a long open time by allowing a (meth)acryloyl group and an isocyanate group to coexist. However, there are problems in that the composition may undergo poor curing depending on the method of irradiation with active energy rays, and furthermore, the composition has insufficient adhesion and bonding to poorly adhesive substrates such as plastic substrates.

[0005] In recent years, applications of urethane adhesives to plastic substrates have been investigated as adhesives for bonding optical disks (Patent Documents 3 to 6). Patent Document 3 describes a urethane (meth)acrylate resin composition obtained by reacting a polyisocyanate compound having two or more isocyanate groups per molecule, at least one polyol selected from polyester polyols, polycaprolactone polyols, polyether polyols, and polycarbonate polyols, and a hydroxyl group-containing (meth)acrylate under specific conditions.

[0006] Furthermore, Patent Document 4 discloses a radiation-curable composition in which a monomer having a urethane bond and / or an oligomer thereof is obtained by reacting at least a compound having two or more isocyanate groups in the molecule, a polymer polyol, and a (meth)acrylate having a hydroxyl group, and the polymer polyol contains two or more skeletons selected from the group consisting of a polyether polyol skeleton, a polyester polyol skeleton, and a polycarbonate polyol skeleton.

[0007] Furthermore, Patent Document 5 describes an adhesive composition for optical discs, which is characterized by containing a polyester polyurethane (meth)acrylate, an unsaturated group-containing compound, and a photopolymerization initiator. However, when these compositions are applied to various plastic or glass surfaces, they do not provide sufficient adhesive strength, and even if adhesive strength is achieved, they suffer from degradation in a 500-hour durability test at 85°C and 85% RH, which is required for components used in electronic devices. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-281935 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-2744 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-307133 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-152289 [Patent Document 5] Japanese Patent Application Publication No. 10-1659 [Non-patent literature]

[0009] [Non-Patent Document 1] "Light and Radiation Curing Technology" August 5, 1985, First Edition, First Printing, Publisher: Hideo Sasaki, Publisher: Taiseisha Co., Ltd. Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide an active energy ray-curable adhesive that has good adhesive strength when bonding dissimilar substrates, such as between plastic substrates (films and sheets), between inorganic substrates such as glass and metal, or between plastic substrates and inorganic substrates such as glass and metal, and that also has high transparency, excellent coatability, and excellent long-term moist heat resistance. [Means for solving the problem]

[0011] As a result of intensive efforts to solve the above problems, the present inventors have found that a composition comprising a polyether urethane (meth)acrylate having a specific structure, a (meth)acrylate compound having a glass transition point of 50°C or higher, and a photopolymerization initiator has excellent curability when cured by active energy rays, has excellent adhesive strength between plastic substrates (films, sheets), between inorganic substrates, and between different substrates such as plastic substrates and glass, and also has excellent long-term moist heat resistance and transparency, and can provide an active energy ray-curable adhesive that has a wide range of coating suitability.

[0012] Specifically, the present invention relates to an active energy ray-curable adhesive containing a polyether urethane (meth)acrylate compound (A), a (meth)acrylate compound (B) (excluding compound (A)), and a photopolymerization initiator (C), characterized in that the polyether urethane (meth)acrylate compound (A) is a reaction product of a polyether polyol (a1) having a number average molecular weight of 2000 or more, a hydroxyl group-containing (meth)acrylate compound (a2), and a polyisocyanate compound (a3), the (meth)acrylate compound (B) contains a (meth)acrylate compound (b1) whose homopolymer glass transition temperature is 50°C or more, and the content of the (meth)acrylate compound (b1) is 20 mass% or more in 100 mass% of the (meth)acrylate compound (B).

[0013] 2. The active energy ray-curable adhesive according to claim 1, wherein the content of the (meth)acrylate compound (b1) is 30% by mass or more in 100% by mass of the (meth)acrylate compound (B).

[0014] The present invention also relates to the active energy ray-curable adhesive, wherein the (meth)acrylate compound (b1) contains a monofunctional (meth)acrylate compound containing a nitrogen atom.

[0015] The present invention also relates to the above-mentioned active energy ray-curable adhesive, wherein the nitrogen atom-containing monofunctional (meth)acrylate compound contains acryloylmorpholine.

[0016] The present invention also relates to the active energy ray-curable adhesive, wherein the content of the (meth)acrylate compound (b1) is 50 mass % or more relative to 100 mass % of the (meth)acrylate compound (B).

[0017] The present invention also relates to the above-mentioned active energy ray-curable adhesive, wherein the polyether polyol (a1) contains polypropylene glycol.

[0018] The present invention also relates to the above-mentioned active energy ray-curable adhesive, wherein the photopolymerization initiator (C) contains an acylphosphine oxide-based radical photopolymerization initiator.

[0019] The present invention also relates to the above-mentioned active energy ray-curable adhesive, which further contains a silane coupling agent.

[0020] The present invention also relates to the above-mentioned active energy ray-curable adhesive, wherein the silane coupling agent contains a silane coupling agent having a (meth)acrylic group.

[0021] The present invention also relates to a laminate having a first substrate, an adhesive layer, and a second substrate, wherein the adhesive layer is a cured product of the above-mentioned active energy ray-curable adhesive.

[0022] The present invention also relates to the laminate, wherein the first substrate and the second substrate are plastic substrates or inorganic substrates.

[0023] The present invention also relates to the above laminate, wherein one of the first substrate and the second substrate is a plastic substrate, and the other of the first substrate and the second substrate is an inorganic substrate. [Effects of the Invention]

[0024] The present invention can provide an active energy ray-curable adhesive that has good adhesive strength not only when joining substrates of the same type but also when joining substrates of different types, has high transparency, excellent coatability, and excellent long-term moist heat resistance. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments for carrying out the active energy ray-curable adhesive of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and can be modified and carried out within a range in which the problems can be solved.

[0026] In this specification, unless otherwise specified, "(meth)acryloyl", "(meth)acrylic", "(meth)acrylic acid", "(meth)acrylate", "(meth)acryloyloxy", or "(meth)acrylamide" means "acryloyl and / or methacryloyl", "acrylic and / or methacrylic", "acrylic acid and / or methacrylic acid", "acrylate and / or methacrylate", "acryloyloxy and / or methacryloyloxy", or "acrylamide and / or methacrylamide", respectively.

[0027] In this specification, the term "active energy rays" refers to energy rays necessary to excite the starting material of the curing reaction from the ground state to the transition state, and includes, but is not limited to, ultraviolet rays and electron beams.

[0028] In this specification, unless otherwise specified, all values ​​are by mass, and mass, parts by mass, and mass% may be abbreviated to amount, parts, and %. Furthermore, unless otherwise specified, the "molecular weight" of resins, polymers, and oligomers refers to the number average molecular weight.

[0029] <Active energy ray curing adhesive> The active energy ray-curable adhesive of the present invention is an active energy ray-curable adhesive containing a polyetherurethane (meth)acrylate compound (A), a (meth)acrylate compound (B), and a photopolymerization initiator (C), characterized in that the polyetherurethane (meth)acrylate compound (A) is a reaction product of a polyether polyol (a1) having a number average molecular weight of 2000 or more, a hydroxyl group-containing (meth)acrylate compound (a2), and a polyisocyanate compound (a3), the (meth)acrylate compound (B) contains a (meth)acrylate compound (b1) whose homopolymer glass transition temperature is 50°C or more, and the content of the (meth)acrylate compound (b1) is 20 mass% or more in 100 mass% of the (meth)acrylate compound (B).

[0030] In the present invention, the (meth)acrylate compound (B) does not include the polyether urethane (meth)acrylate compound (A).

[0031] <Polyether urethane (meth)acrylate compound (A)> The polyether urethane (meth)acrylate compound (A) of the present invention can be synthesized from a polyether polyol (a1), a hydroxyl group-containing (meth)acrylate compound (a2), and a polyisocyanate compound (a3).

[0032] Examples of the polyether polyol (a1) include a product obtained by addition polymerization of one or more alkylene oxides, such as ethylene oxide, propylene oxide, and butylene oxide, to a compound having two or more active hydrogen atoms; polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran; modified polytetramethylene glycol obtained by copolymerizing tetrahydrofuran and alkyl-substituted tetrahydrofuran; and modified polytetramethylene glycol obtained by copolymerizing neopentyl glycol and tetrahydrofuran. The polyether polyols may be used alone or in combination of two or more.

[0033] Examples of the compound having two or more active hydrogens include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, and 1,6-hexanediol. 2,5-Hexanediol, 1,7-Heptanediol, 1,8-Octanediol, 1,9-Nonanediol, 1,10-Decanediol, 1,11-Undecanediol, 1,12-Dodecanediol, 2-Methyl-1,3-propanediol, Neopentyl Glycol, 2-Butyl-2-Ethyl-1,3-Propanediol, 3-Methyl-1,5-Pentanediol, 2-Ethyl-1,3-Propanediol, 3-Methyl-1,5-Pentanediol , 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4'-bisphenol, and other relatively low molecular weight dihydroxy compounds; alicyclic polyols such as 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1,4-cyclohexanedimethanol, hydroxypropylcyclohexanol, dicyclohexanediol, hydroxypropyltricyclo[5,3,1,1]dodecanol, spiro[3,4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, and 1,3-adamantanediol; and polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Among these, it is more preferable to use an aliphatic polyether polyol from the viewpoint of imparting good adhesive properties, and it is particularly preferable to use polypropylene glycol obtained by ring-opening polymerization of propylene glycol.

[0034] The number average molecular weight of the polyether polyol (a1) of the present invention is characterized by being 2000 or more, and is appropriately determined in consideration of the physical properties as an adhesive. It is preferably 5000 or less, and more preferably 2000 to 4000. If it is less than 2000, the viscosity as a UV adhesive tends to be too low, resulting in poor coatability, while if it is 5000 or less, it is easy to obtain and easy to synthesize.

[0035] The polyisocyanate (a3) ​​used in the present invention includes various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are commonly used in the production of polyurethane resins, such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and cyclohexane. Examples of suitable diisocyanate compounds include 1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanato-benzyl chloride, and dimer diisocyanate in which the carboxyl groups of dimer acid are converted to isocyanate groups. These diisocyanate compounds can be used alone or in combination of two or more.

[0036] The hydroxyl group-containing (meth)acrylate compound (a2) used in the present invention includes compounds having one or more hydroxyl groups and one or more (meth)acryloyl groups. Examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, 2-hydroxyalkyl (meth)acryloyl phosphate, 4-hydroxycyclohexyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, lactone-modified hydroxyethyl (meth)acrylate, and polyether-modified hydroxyethyl (meth)acrylate, of which 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is particularly preferred.

[0037] The content of the polyether urethane (meth)acrylate compound (A) in the active energy ray-curable adhesive is preferably from 10 to 80 mass %, more preferably from 20 to 70 mass %, and particularly preferably from 30 to 60 mass %.

[0038] It is impossible or practically unrealistic to specify and describe how the polyether polyol (a1), the hydroxyl group-containing (meth)acrylate compound (a2), and the polyisocyanate compound (a3) ​​are bonded in the polyether urethane (meth)acrylate compound (A), so the description is based on the production method.

[0039] <Method for producing polyether urethane (meth)acrylate compound (A)> In the present invention, the polyether urethane (meth)acrylate compound (A) is obtained by reacting the polyether polyol (a1), the hydroxyl group-containing (meth)acrylate compound (a2), and the polyisocyanate compound (a3). That is, in the present invention, the polyether urethane (meth)acrylate compound (A) is synthesized by reacting an isocyanate group in the polyisocyanate compound (a3), a hydroxyl group in the polyether diol (a1), and a hydroxyl group in the hydroxyl group-containing (meth)acrylate compound (a2), respectively. This synthesis is preferably carried out by reacting a hydroxyl group-containing (meth)acrylate compound (a2) with a polyisocyanate compound (a3), and then reacting the compound with a polyether diol (a1).

[0040] The reaction ratio when reacting the polyether polyol (a1), polyisocyanate compound (a3), and hydroxyl group-containing (meth)acrylate compound (a2) is such that the polyisocyanate compound (a3) ​​contains 1 equivalent of isocyanate groups per equivalent of the total hydroxyl groups in the polyether polyol (a1) and the hydroxyl group-containing (meth)acrylate compound (a2). When chain extension of the polyether polyol is involved using polyisocyanate, they are mixed in a ratio according to the desired degree of chain extension, and are used so that the equivalents of hydroxyl groups and isocyanate groups are equal overall. However, in order to improve physical properties such as adhesiveness, it is also possible to synthesize the resin with an increased equivalent weight of isocyanate groups rather than with the same equivalent weight.

[0041] In the present invention, the amount of isocyanate groups in the polyether urethane (meth)acrylate compound (A) is determined by the IR spectrum at 2240 cm -1 A specific peak appears nearby, and the progress of the reaction can be checked by comparing it with other peaks or by the disappearance of the peak.

[0042] Furthermore, when reacting the polyether diol (a1), the polyisocyanate compound (a3), and the hydroxyl group-containing (meth)acrylate compound (a2), it is preferable from the viewpoint of reaction control to gradually add the hydroxyl group-containing (meth)acrylate compound (a2) dropwise to the polyisocyanate compound (a3), and then, when the heat generation subsides after the dropwise addition, add the polyether polyol (a1).

[0043] Furthermore, a catalyst can be used in the reaction (so-called urethanization reaction) of the polyether polyol (a1), polyisocyanate compound (a3), and hydroxyl group-containing (meth)acrylate compound (a2). Usable catalysts include, for example, tertiary amine catalysts such as triethylamine and dimethylaniline; and metal catalysts such as tin and zinc. These catalysts are typically used in an amount of 0 to 1000 ppm relative to the polyether polyol compound. The reaction temperature for this urethanization reaction is preferably 50 to 80°C.

[0044] The number average molecular weight of the polyether urethane (meth)acrylate compound (A) used in the present invention is preferably 2800 to 30000, since this allows the viscosity of the resulting adhesive to be optimal for application without using an organic solvent.

[0045] <(Meth)acrylate Compound (B)> The (meth)acrylate compound (B) used in the present invention is preferably (1) a monofunctional or polyfunctional (meth)acrylate monomer, or (2) a (meth)acrylate oligomer (reactive oligomer), and by using these appropriately, the viscosity of the active energy ray-curable adhesive can be adjusted.

[0046] Examples of monofunctional (meth)acrylate monomers include alkyl (having 2 to 18 carbon atoms) (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate, and further examples include benzyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and tricyclodecane monomethylol (meth)acrylate.

[0047] Examples of polyfunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, pentyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate (commonly known as Manda), hydroxypivalyl hydroxypivalate dicaprolactonate di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl-2,4-Pentanediol di(meth)acrylate, bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, water-added bisphenol A tetraethylene oxide adduct di(meth)acrylate, water-added bisphenol F tetraethylene oxide adduct di(meth)acrylate, water-added bisphenol A di(meth)acrylate, water-added bisphenol F di(meth)acrylate, glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tricaprolactonate tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, pentaerythritol Examples of the acrylates that can be used include thritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane tetracaprolactonate, tetra(meth)acrylate, ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, ditrimethylolhexane tetra(meth)acrylate, ditrimethyloloctane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, and tripentaerythritol octa(meth)acrylate.

[0048] As the oligomer (reactive oligomer) of (meth)acrylates, alkyd acrylate, epoxy acrylate, urethane-modified acrylate, etc. are used.

[0049] These (meth)acrylate compounds (B) can be used alone or in combination of two or more.

[0050] The (meth)acrylate compound (B) used in the present invention is characterized by containing a (meth)acrylate compound (b1) whose homopolymer has a glass transition temperature of 50°C or higher. Examples of (meth)acrylate compounds with a homopolymer glass transition temperature of 50°C or higher include isobornyl acrylate (94°C), phenyl acrylate (57°C), acrylamide (165°C), acrylonitrile (105°C), benzyl methacrylate (54°C), methyl methacrylate (105°C), ethyl methacrylate (65°C), isopropyl methacrylate (81°C), isobutyl methacrylate (53°C), sec-butyl methacrylate (60°C), t-butyl methacrylate (118°C), cyclohexyl methacrylate (83°C), 2-hydroxyethyl methacrylate (8 5°C), allyl methacrylate (52°C), isobornyl methacrylate (110°C), dimethylacrylamide (DMAA; 119°C), acryloylmorpholine (ACMO; 145°C), dimethylaminopropyl acrylamide (DMAPAA; 134°C), isopropyl acrylamide (NIPAM; 134°C), diethylacrylamide (DEAA; 81°C), hydroxyethyl acrylamide (HEAA; 98°C), 2-acryloxymethyl methyl acrylate (AOMA; 135°C), and the like. These compounds may be used alone or in combination of two or more. The glass transition temperature is preferably 70°C or higher, more preferably 100°C or higher and 200°C or lower, from the viewpoint of adhesive strength between different substrates.

[0051] Among the above, it is preferable to contain a nitrogen atom-containing monofunctional (meth)acrylate compound, and it is particularly preferable to contain acryloylmorpholine, because when combined with polyether urethane acrylate, this can exhibit excellent adhesion to plastic films and inorganic compounds.

[0052] The content of the (meth)acrylate compound (b1) having a homopolymer glass transition temperature of 50°C or higher is 20% by mass or higher, preferably 30% by mass or higher, more preferably 50 to 100% by mass, and even more preferably 60 to 90% by mass, based on 100% by mass of the total (meth)acrylate compounds (B). When a nitrogen atom-containing monofunctional (meth)acrylate compound is used, the content thereof is preferably 30 mass %, more preferably 50 to 100 mass %, and particularly preferably 60 to 90 mass %, relative to 100 mass % of the total (meth)acrylate compounds (B). When acryloylmorpholine is used, the content is 20% by mass or more, preferably 30% by mass, more preferably 50 to 100% by mass, and particularly preferably 60 to 90% by mass, based on 100% by mass of the total (meth)acrylate compounds (B).

[0053] The content of the (meth)acrylate compound (B) is preferably from 10 to 80 mass %, more preferably from 25 to 65 mass %, and particularly preferably from 25 to 50 mass %, based on the active energy ray-curable adhesive composition.

[0054] The molecular weight of the (meth)acrylate compound (B) is the molecular weight calculated from its structural formula in the case of a monofunctional or polyfunctional (meth)acrylate monomer, and indicates the number average molecular weight in the case of an oligomer (reactive oligomer) having an ethylenically unsaturated double bond.

[0055] The glass transition temperature can be measured using a differential scanning calorimeter at a temperature rise rate of 10°C / min in accordance with JIS-K7121. Examples of the differential scanning calorimeter include "DSC7020" manufactured by Hitachi High-Tech Science Corporation.

[0056] <Photopolymerization initiator (C)> The photopolymerization initiator used in the present invention is preferably a photoradical polymerization initiator, and known examples of the photoradical polymerization initiator include alkylphenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, oxime ester-based photoradical polymerization initiators, benzophenone-based photoradical polymerization initiators, and thioxanthone-based photoradical polymerization initiators.

[0057] Examples of alkylphenone-based photoradical polymerization initiators include 2,2'-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, and 2-benzylmethyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone. Examples of the acylphosphine oxide photoradical polymerization initiator include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis-2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide. Examples of oxime ester-based photoradical polymerization initiators include (2E)-2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one. Examples of benzophenone-based photoradical polymerization initiators include methyl o-benzoylbenzoate, benzophenone, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 4,4-diethylaminobenzophenone. Examples of thioxanthone-based photoradical polymerization initiators include 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 1-chloro-4-propoxythioxanthone.

[0058] Among these, acylphosphine oxide-based photoradical polymerization initiators are preferred in terms of curability and adhesiveness, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is particularly preferred. In addition, a photoaccelerator such as ethyl p-dimethylaminobenzoate or pentyl 4-dimethylaminobenzoate may be used in combination with the photopolymerization initiator. The content of the photopolymerization initiator is preferably from 0.1 to 20 mass %, more preferably from 0.5 to 15 mass %, and particularly preferably from 1 to 10 mass %, based on the active energy ray-curable adhesive composition.

[0059] (Silane coupling agent) In the present invention, it is preferable to use a silane coupling agent. Silane coupling agents are compounds having two or more alkoxysilyl groups, and they significantly improve adhesion to inorganic substrates. Specific examples include trimethoxysilylpropyl (meth)acrylate, triethoxysilylpropyl (meth)acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, p-styryltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Those having a (meth)acrylic group are preferred, and trimethoxysilylpropyl (meth)acrylate is particularly preferred because of its UV curability. The content of the silane coupling agent is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, and particularly preferably 0.1 to 1 mass %, based on the active energy ray-curable adhesive composition. Even if the silane coupling agent has a (meth)acrylic group, it is not included in the (meth)acrylate compound (B).

[0060] (non-reactive resin) In the present invention, a non-reactive resin can be appropriately incorporated as needed. The non-reactive resin is a thermosetting or thermoplastic resin that does not have a reactive functional group such as an ethylenically unsaturated double bond, and examples thereof include acrylic resins, epoxy resins, polyurethane resins, cellulose derivatives (e.g., ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymers, polyamide resins, polyvinyl acetal resins, diallyl phthalate resins, and synthetic rubbers such as butadiene-acrylonitrile copolymers. One or more of these resins can be used. All of these resins are soluble in the compound (B) having an ethylenically unsaturated double bond.

[0061] (Other additives) Other additives that can be used include, for example, silicone additives, leveling agents, extenders, and the like.

[0062] <Laminate> The laminate of the present invention has at least a first substrate, an adhesive layer, and a second substrate, and is characterized in that the adhesive layer is a cured product of the active energy ray-curable adhesive.

[0063] (base material) The substrates used in the present invention include those in which the first substrate and the second substrate are the same type, such as between relatively non-polar, poorly adhesive substrates such as polyolefin resins, such as plastic substrates, or between highly polar glass substrates as inorganic substrates, or those in which the first substrate and the second substrate are different types, such as between highly polar glass and a non-polar plastic substrate. The active energy ray-curable adhesive of the present invention can improve adhesive strength even between such difficult-to-adhere substrates, and is also highly transparent and has excellent coatability.

[0064] Examples of plastic substrates include optical-grade PET films and polycarbonate films. Examples of PET films include Lumirror U34, Lumirror U48, and Lumirror U40 manufactured by Toray Industries, Inc., and Cosmoshine A4160 and Cosmoshine A4360 manufactured by Toyobo Co., Ltd., with Lumirror U34, Cosmoshine A4160, and Cosmoshine A4360 having an easy-adhesion layer being preferred in terms of adhesiveness. Examples of polycarbonate films include Iupilon FS2000L manufactured by Mitsubishi Gas Chemical Company, Inc. and PureAce WR manufactured by Teijin Limited.

[0065] Inorganic substrates include alkali-free glass (EAGLE XG, etc.), ITO, and silicon nitride sputtered glass plates.

[0066] (adhesive layer) The adhesive layer of the present invention is a cured product of the active energy ray-curable adhesive. The active energy ray-curable adhesive can be formed into a film having a thickness of 0.1 to 500 μm by a coating method such as a roll coater, knife coater, or dispenser, or by a printing method such as offset printing, gravure printing, letterpress printing, or silk screen printing. The formed film can be cured and bonded by irradiating it with active energy rays such as ultraviolet rays or electron beams.

[0067] The active energy ray-curable adhesive of the present invention can be suitably used for display materials, electronic materials, optical materials, and the like.

[0068] In the present invention, the number average molecular weight was measured using a gel permeation chromatography (HLC-8020, hereinafter referred to as GPC) manufactured by Tosoh Corporation. A calibration curve was prepared using a standard polystyrene sample. Tetrahydrofuran was used as the eluent, and three TSK gel Super HM-M columns (manufactured by Tosoh Corporation) were used. Measurements were performed at a flow rate of 0.6 ml / min, an injection volume of 10 μl, and a column temperature of 40°C. [Example]

[0069] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % represent parts by mass and % by mass unless otherwise noted.

[0070] [Polyether urethane (meth)acrylate synthesis example 1] A round-bottom flask equipped with a stirrer, thermometer, water divider, and nitrogen gas inlet tube was charged with 20.2 parts of isophorone diisocyanate and 0.3 parts of dibutyltin laurate, and 6.6 parts of 4-hydroxybutyl acrylate was added dropwise while stirring under a nitrogen stream. After the addition was complete, the temperature was maintained at 80°C for 1 hour. 273.2 parts of PPG4000 (polypropylene glycol molecular weight 4000) was then added as a diol compound, and the reaction was carried out at 80°C for 4 hours under a nitrogen stream. The reaction was terminated after confirming the disappearance of the isocyanate groups by IR, yielding a polyether urethane acrylate with a number average molecular weight of 15,200.

[0071] [Polyether urethane (meth)acrylate synthesis examples 2 to 7] Polyetherurethane (meth)acrylate Synthesis Examples 2 to 7 were carried out in the same manner as Polyetherurethane (meth)acrylate Synthesis Example 1, except that the type and amount of polyether polyol, isophorone diisocyanate, and amount of 4-hydroxybutyl acrylate were changed to the types and amounts shown in Table 1, to obtain polyetherurethane (meth)acrylates (A-2) to (A-6).

[0072] [Table 1] The polyether polyols in the table are as follows: PPG2000 (Polypropylene glycol, molecular weight 2000) PPG3000 (Polypropylene glycol, molecular weight 3000) PPG4000 (Polypropylene glycol, molecular weight 4000) PTMG2000 (Polytetramethylene glycol, molecular weight 2000) PTMG3000 (Polytetramethylene glycol, molecular weight 3000) PPG1000 (Polypropylene glycol, molecular weight 1000)

[0073] [Example 1] (Preparation of active energy ray curing adhesive) An active energy ray-curable adhesive was obtained by mixing 60 parts of the polyether urethane (meth)acrylate (A-1) obtained in Synthesis Example 1 as the polyether urethane (meth)acrylate (compound (A)), 25 parts of acryloylmorpholine and 10 parts of methyl 2-allyloxymethylacrylate as the (meth)acrylate compound (B), 4.8 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide as an initiator, and 0.2 parts of trimethoxysilylpropyl acrylate as a silane coupling agent using a disper. (Creating a laminate) This active energy ray-curable adhesive was applied to a transparent film or alkali-free glass with an applicator at a thickness of 2 mil, and after placing a transparent film on top of it, air bubbles were removed with a rubber roller and the films were adhered together. After that, a UV lamp was irradiated from the side of the adhered transparent film to cure the active energy ray-curable adhesive and completely adhere the transparent film. UV irradiation conditions: 80W / cm high-pressure mercury lamp, cumulative light intensity 400nJ (UVA) The transparent film used was a polyethylene terephthalate (PET) film with an easy-adhesion layer (Toyobo Cosmoshine A4360), and the alkali-free glass used was "EAGLE XG."

[0074] (evaluation) The laminates prepared with the "easy-adhesion PET / adhesive / easy-adhesion PET" configuration and the "easy-adhesion PET / adhesive / alkali-free glass" configuration were subjected to the following 180° peel strength test. The liquid viscosity of the active energy ray curable adhesive was also measured. The evaluation results are shown in Table 2 along with the dosages. In the 180° peel strength test and liquid viscosity evaluation criteria, a rating of △ or higher is considered practical.

[0075] <180° peel strength test> A 180° peel strength test was performed using a Tensilon tensile tester at a width of 25 mm and a pulling speed of 20 mm / min to measure the peel strength (N / 25 mm). The results were evaluated according to the following criteria. For the initial adhesive strength, the test was performed on the same day after UV irradiation, and a sample prepared at the same time was exposed to the tester at 85°C and 85% RH for 500 hours before undergoing the 180° peel test. (Evaluation criteria) ◎ :35N or more ○: 30N or more, less than 35N 〇△: 25N or more, less than 30N △: 15N or more, less than 25N ×: Less than 15N

[0076] <Liquid viscosity> The viscosity specified in JIS Z 8803 was measured using an E-type viscometer (TV-100EH manufactured by Toki Sangyo Co., Ltd.) The results were evaluated according to the following evaluation criteria. (Evaluation criteria) ○: 2 Pa·s or more and less than 4 Pa·s △: 4 Pa·s or more but less than 6 Pa·s, or less than 2 Pa·s ×:6Pa·s or more

[0077] [Examples 2 to 14, Comparative Examples 1 to 4] Except for changing the formulation amounts to those shown in Table 2, an active energy ray-curable adhesive was prepared in the same manner as in Example 1, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0078] [Table 2] The abbreviations in Table 2 are as follows: Art Resin UN-6207: A polyether urethane acrylate (manufactured by Negami Chemical Industries) with a number average molecular weight of approximately 12,000, which is a reaction product of polypropylene glycol with a number average molecular weight of 4,000, isophorone diisocyanate, and hydroxybutyl acrylate. Art Resin UN-7700: A polyester urethane acrylate with a number average molecular weight of approximately 8000 (manufactured by Negami Chemical Industries). Art Resin UN-7702: A polyester urethane acrylate with a number average molecular weight of approximately 20,000 (manufactured by Negami Chemical Industries).

[0079] From the examples in Table 2, it was found that by using polyether urethane (meth)acrylate (A) and further using a (meth)acrylate compound (b1) whose homopolymer has a glass transition temperature of 50°C or higher, excellent adhesive strength was exhibited, and in particular, by including a monofunctional (meth)acrylate compound containing a nitrogen atom in the (meth)acrylate compound (b1), excellent adhesive strength was exhibited as an adhesive between films or between different substrates such as glass and film, and further, an active energy ray-curable adhesive was obtained that had good initial adhesive strength and adhesive strength even after 500 hours of exposure to a high-temperature, high-humidity environment of 85°C and 85% RH.

Claims

1. An active energy ray-curable adhesive containing a polyether urethane (meth)acrylate compound (A), a (meth)acrylate compound (B) (excluding compound (A)), and a photopolymerization initiator (C), the polyether urethane (meth)acrylate compound (A) is a reaction product of a polyether polyol (a1) having a number average molecular weight of 2,000 or more, a hydroxyl group-containing (meth)acrylate compound (a2), and a polyisocyanate compound (a3); The (meth)acrylate compound (B) contains a (meth)acrylate compound (b1) having a homopolymer glass transition temperature of 50°C or higher, An active energy ray-curable adhesive, characterized in that the content of the (meth)acrylate compound (b1) is 20 mass% or more in 100 mass% of the (meth)acrylate compound (B).

2. 2. The active energy ray-curable adhesive according to claim 1, wherein the content of the (meth)acrylate compound (b1) is 30 mass% or more in 100 mass% of the (meth)acrylate compound (B).

3. 2. The active energy ray-curable adhesive according to claim 1, wherein the (meth)acrylate compound (b1) comprises a monofunctional (meth)acrylate compound containing a nitrogen atom.

4. 4. The active energy ray-curable adhesive according to claim 3, wherein the nitrogen atom-containing monofunctional (meth)acrylate compound contains acryloylmorpholine.

5. 2. The active energy ray-curable adhesive according to claim 1, wherein the content of the (meth)acrylate compound (b1) is 50 mass % or more relative to 100 mass % of the (meth)acrylate compound (B).

6. 2. The active energy ray-curable adhesive according to claim 1, wherein the polyether polyol (a1) contains polypropylene glycol.

7. 2. The active energy ray-curable adhesive according to claim 1, wherein the photopolymerization initiator (C) contains an acylphosphine oxide-based radical photopolymerization initiator.

8. 2. The active energy ray-curable adhesive according to claim 1, further comprising a silane coupling agent.

9. 9. The active energy ray-curable adhesive according to claim 8, wherein the silane coupling agent comprises a silane coupling agent having a (meth)acrylic group.

10. A laminate having a first substrate, an adhesive layer, and a second substrate, wherein the adhesive layer is a cured product of the active energy ray-curable adhesive according to any one of claims 1 to 9.

11. 11. The laminate according to claim 10, wherein the first substrate and the second substrate are plastic substrates or inorganic substrates.

12. 12. The laminate according to claim 11, wherein one of the first substrate and the second substrate is a plastic substrate, and the other of the first substrate and the second substrate is an inorganic substrate.

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