Active energy ray-curable adhesive composition, cured product, and laminate

Abstract

To provide an active energy ray-curable adhesive composition which gives a cured product layer having high adhesive force at an initial stage and after high-temperature exposure and also having excellent thermal yellowing resistance and wet heat whitening resistance.SOLUTION: The active energy ray-curable adhesive composition contains specific amounts of: a urethane (meth)acrylate (A) which is a reaction product of a chain polyether polyol (a1) having a C4 or higher alkylene chain in a repeating unit, a polyisocyanate (a2), and a mono(meth)acrylate (a3-1) having a hydroxy group or a mono(meth)acrylate (a3-2) having an isocyanate group and has a weight average molecular weight of 50,000-200,000; a mono(meth)acrylate (B) having no hydroxy group; and a mono(meth)acrylate (C) having a hydroxy group. The component (B) contains an alkyl mono(meth)acrylate (B1) having a C6-20 alkyl group and a cycloalkyl mono(meth)acrylate (B2) in a specific mass ratio.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable pressure-sensitive adhesive composition, a cured product, and a laminate. [Background technology]

[0002] Adhesives are used in mobile devices such as smartphones and tablets, digital home appliances such as digital cameras and audio equipment, communication devices such as radios and modems, as well as in car navigation systems, audio displays, rear seat entertainment systems, and other in-vehicle touch panels.

[0003] Adhesives used in automotive touch panels are required to have not only adhesive strength, but also the ability to not turn yellow even after exposure to high temperatures (high heat yellowing resistance), maintain high adhesive strength, and not turn white even under high temperature and humidity conditions (high humidity and heat whitening resistance).

[0004] In order to solve these problems, the present applicant has also disclosed an ultraviolet-curable pressure-sensitive adhesive that is prepared by blending a specific photopolymerization initiator and an antioxidant with a polyether-based polyurethane (meth)acrylate, an alkyl mono(meth)acrylate having an alkyl group with 4 to 12 carbon atoms, a cycloalkyl mono(meth)acrylate having a cycloalkyl group with 6 to 10 carbon atoms, or a primary hydroxyl group-containing mono(meth)acrylate (Patent Document 1). However, these required properties have not been satisfied, and there is room for improvement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-100403 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an active energy ray-curable pressure-sensitive adhesive composition that provides a cured product layer that has high adhesive strength both initially and after exposure to high temperatures, and that is also excellent in resistance to heat yellowing and humidity-heat whitening. [Means for solving the problem]

[0007] The present inventors have conducted extensive research and found that the above-mentioned problems can be solved. That is, the present invention relates to the following active energy ray-curable pressure-sensitive adhesive composition, cured product, and laminate.

[0008] 1. A urethane (meth)acrylate (A) having a weight average molecular weight of 50,000 to 200,000, which is a reaction product of a linear polyether polyol (a1) having an alkylene chain having 4 or more carbon atoms as a repeating unit, a polyisocyanate (a2), and a mono(meth)acrylate (a3-1) having a hydroxy group or a mono(meth)acrylate (a3-2) having an isocyanate group; A mono(meth)acrylate (B) having no hydroxy group, and Contains a mono(meth)acrylate (C) having a hydroxy group, The component (B) is an alkyl mono(meth)acrylate (B1) having an alkyl group having 6 to 20 carbon atoms and a cycloalkyl mono(meth)acrylate (B2), the ratio of the nonvolatile mass of the component (B1) to the component (B2) [(B1) / (B2)] is 0.05 or more and less than 1; An active energy ray-curable pressure-sensitive adhesive composition, in which the content of component (C) is 10 to 35 mass % when the total of components (A), (B), and (C) is taken as 100 mass %.

[0009] 2. The active energy ray-curable pressure-sensitive adhesive composition according to item 1 above, further comprising a tackifier resin (D).

[0010] 3. A cured product of the active energy ray-curable pressure-sensitive adhesive composition according to the preceding item 1 or 2.

[0011] 4. A laminate having the cured product according to item 3 on at least one surface of a substrate. [Effects of the Invention]

[0012] The active energy ray-curable pressure-sensitive adhesive composition according to the present invention (hereinafter simply referred to as "pressure-sensitive adhesive composition") provides a cured product layer (hereinafter also referred to as "cured product layer") that has high adhesive strength both initially and after exposure to high temperatures, and is also excellent in resistance to heat yellowing and wet heat whitening. DETAILED DESCRIPTION OF THE INVENTION

[0013] The pressure-sensitive adhesive composition of the present invention contains a specific polyurethane (meth)acrylate (A) (hereinafter referred to as component (A)), a mono(meth)acrylate (B) (hereinafter referred to as component (B)) that does not have a hydroxy group, and a mono(meth)acrylate (C) (hereinafter referred to as component (C)) that has a hydroxy group.

[0014] The component (A) of the present invention is a reaction product of a linear polyether polyol (a1) (hereinafter referred to as the component (a1)) having an alkylene chain with 4 or more carbon atoms as a repeating unit, a polyisocyanate (a2) (hereinafter referred to as the component (a2)), and a mono(meth)acrylate (a3-1) having a hydroxy group (hereinafter referred to as the component (a3-1)) or a mono(meth)acrylate (a3-2) having an isocyanate group (hereinafter referred to as the component (a3-2)).

[0015] Component (a1) is a linear polyether polyol having an alkylene chain with four or more carbon atoms as a repeating unit. The structure having an alkylene chain with four or more carbon atoms as a repeating unit is represented by general formula (1), and when component (a1) is used, the resulting component (A) tends to exhibit a weight-average molecular weight described below, and a cured product layer containing component (A) tends to exhibit excellent heat yellowing resistance.

[0016] [C1]HO-[(CH2) m O] n -H···(1) (In formula (1), m represents an integer of 4 or more, and n represents an integer of 2 or more.)

[0017] As the component (a1), polytetramethylene glycol is preferred because the cured product layer tends to exhibit excellent heat yellowing resistance.

[0018] Examples of commercially available products of component (a1) include "PTMG650", "PTMG850", "PTMG1000", "PTMG1300", "PTMG1500", "PTMG1800", "PTMG2000", "PTMG3000", "PTMG3200", "BioPTMG650", "BioPTMG1000", "BioPTMG2000", and "BioPTMG3000" (all manufactured by Mitsubishi Chemical Corporation). These may be used alone or in combination of two or more.

[0019] Furthermore, a polyol (a1') other than the component (a1) (hereinafter referred to as the component (a1')) may be used in combination. Examples of the component (a1') include linear polyether polyols having an alkylene chain with 3 or less carbon atoms, such as polyethylene glycol and polypropylene glycol; polyester polyols, poly(meth)acrylic polyols, polyolefin polyols, polycaprolactone polyols, and polycarbonate polyols. These may be used alone or in combination of two or more. Note that (meth)acrylic means acrylic or methacrylic.

[0020] The amount of the component (a1') used is preferably 30% by mass or less, and more preferably 20% by mass or less, with the total of the components (a1) and (a1') being 100% by mass.

[0021] As for the physical properties of the component (a1), for example, the number average molecular weight (polystyrene equivalent value determined by gel permeation chromatography (GPC)) is preferably 1000 to 3000, more preferably 2000 to 3000, from the viewpoint of adhesive strength.

[0022] Examples of the component (a2) include: Aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; Aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; Examples of the diisocyanate include alicyclic diisocyanates such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated tolylene diisocyanate. These may be used alone or in combination of two or more. Furthermore, as component (a2), nurates, adducts, or biuret forms of these may also be used.

[0023] Among these, aliphatic diisocyanates and alicyclic diisocyanates are preferred, and hexamethylene diisocyanate and isophorone diisocyanate are more preferred, since the cured product layer is likely to exhibit high adhesive strength even after being exposed to high temperatures.

[0024] Examples of the component (a3-1) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate. These may be used alone or in combination of two or more.

[0025] Examples of the component (a3-2) include 2-isocyanatoethyl (meth)acrylate, 1,1-bis(acryloyloxymethyl)ethyl isocyanate, 2-(o-[1'-methylpropylideneamino]carboxyamino)ethyl methacrylate, etc. These may be used alone or in combination of two or more.

[0026] Among these, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-isocyanatoethyl (meth)acrylate are preferred because they readily react with the functional groups (hydroxy groups derived from component (a1) or isocyanate groups derived from component (a2)) of the urethane prepolymer formed by the reaction of component (a1) and component (a2). Note that (meth)acrylate means acrylate or methacrylate.

[0027] Component (A) is produced by various known methods. Hereinafter, component (a3) ​​will be described separately as component (A1) obtained using component (a3-1) (hereinafter referred to as component (A1)), and component (A2) obtained using component (a3-2) (hereinafter referred to as component (A2)).

[0028] The (A1) component can be obtained, for example, by reacting the (a1) component with the (a2) component to produce an isocyanate group-terminated urethane prepolymer (hereinafter referred to as the (A1') component), and then reacting the (A1') component with the (a3-1) component. The reaction conditions are preferably a temperature of 70 to 85°C and a reaction time of 1 to 5 hours. The ratio of the (a1) component to the (a2) component is determined by the number of moles of isocyanate groups in the (a2) component (NCO (a2) ) and the number of moles of hydroxyl groups in the (a1) component (OH (a1) ) and the ratio (NCO (a2) / OH (a1) ) is preferably 1.01 to 2. The ratio of the component (A1') to the component (a3-1) used is determined by the ratio of the number of moles of isocyanate groups (NCO (A1’) ) and the number of moles of hydroxyl groups in the latter (OH (a3-1) ) and the ratio (NCO (A1’) / OH (a3-1) ) is preferably 0.25 to 1.

[0029] Component (A2) can be prepared by reacting components (a1) and (a2) to obtain a hydroxyl-terminated urethane prepolymer (hereinafter referred to as component (A2')), and then reacting component (A2') with component (a3-2). The reaction temperature and reaction time are the same as for component (A1). The ratio of component (a1) to component (a2) is preferably (NCO (a2) / OH (a1) The ratio of the component (A2') to the component (a3-2) is determined by the ratio of the number of moles of isocyanate groups (NCO (a3-2) ) and the number of moles of hydroxyl groups in the former (OH (A2’) ) and the ratio (NCO (a3-2) / OH (A2’) ) is preferably 0.5 to 1.

[0030] The production of these components (A1) and (A2) may be carried out in the presence of an organic solvent, as described below, but is preferably carried out in the absence of a solvent to reduce environmental impact.Furthermore, the production of these components can also be carried out in the presence of component (B1), as described below.

[0031] The weight-average molecular weight of the resulting (A) component is 50,000 to 200,000. If the weight-average molecular weight is less than 50,000, the adhesive strength of the cured layer after exposure to high temperatures is likely to decrease, and the resistance to wet heat whitening is also likely to be poor. On the other hand, if the weight-average molecular weight exceeds 200,000, the viscosity increases, making it difficult to prepare the adhesive composition, or the chain length of the (A) component increases, making it difficult to cure the adhesive composition, and the initial adhesive strength of the resulting cured layer is likely to decrease. From the same perspective, the weight-average molecular weight of the (A) component is preferably 50,000 to 150,000, more preferably 60,000 to 100,000. The weight-average molecular weight is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0032] When the total of the components (A), (B), and (C) is taken as 100% by mass, the content of the component (A) is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and even more preferably 20 to 40% by mass in terms of nonvolatile mass (the same applies hereinafter), from the viewpoints of providing a cured product layer with high adhesive strength both initially and after exposure to high temperatures and also excellent resistance to heat yellowing.

[0033] Component (B) is a mono(meth)acrylate that does not have a hydroxy group, and is a component that enables the cured product layer to exhibit high adhesive strength both initially and after exposure to high temperatures.

[0034] When the total of the components (A), (B), and (C) is taken as 100% by mass, the content of the component (B) is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass, since the cured product layer is likely to exhibit high adhesive strength initially and even after exposure to high temperatures.

[0035] The pressure-sensitive adhesive composition of the present invention essentially contains, as component (B), an alkyl mono(meth)acrylate (B1) having an alkyl group having 6 to 20 carbon atoms (hereinafter referred to as component (B1)) and a cycloalkyl mono(meth)acrylate (B2) (hereinafter referred to as component (B2)).

[0036] Examples of the component (B1) include n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, and undecyl (meth)acrylate. Examples of the acrylate include acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate (n-dodecyl (meth)acrylate), myristyl (meth)acrylate (n-tetradecyl (meth)acrylate), palmityl (meth)acrylate (n-hexadecyl (meth)acrylate), stearyl (meth)acrylate (n-octadecyl (meth)acrylate), isostearyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0037] Among these, alkyl mono(meth)acrylates having an alkyl group with 7 to 15 carbon atoms are preferred, and 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, lauryl(meth)acrylate, and isostearyl(meth)acrylate are more preferred, since the cured product layer is likely to exhibit high adhesive strength initially and even after exposure to high temperatures.

[0038] Examples of the component (B2) include monocyclic (meth)acrylates such as cyclopentyl (meth)acrylate and cyclohexyl (meth)acrylate; bicyclic (meth)acrylates such as norbornyl (meth)acrylate, isobornyl (meth)acrylate, norbornanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentanyloxyethyl (meth)acrylate; Examples include tricyclic (meth)acrylates such as tricyclodecanedimethylol di(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0039] Among these, bicyclic (meth)acrylates are preferred, and isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate are more preferred, since the cured layer is likely to exhibit high adhesive strength even after exposure to high temperatures and is likely to have excellent resistance to heat yellowing.

[0040] The ratio of the nonvolatile mass of the (B1) component to the (B2) component [(B1) / (B2)] is 0.05 or more and less than 1. If this ratio is less than 0.05, the adhesive composition will have reduced tackiness when cured, making it difficult to exert adhesive strength and also prone to poor resistance to wet heat whitening, while if this ratio is 1 or more, the adhesive strength of the cured product layer will be prone to decrease after exposure to high temperatures. From the same viewpoint, this ratio is preferably 0.1 or more and 0.8 or less, more preferably 0.2 or more and 0.6 or less.

[0041] The pressure-sensitive adhesive composition of the present invention may contain a mono(meth)acrylate (B') (hereinafter referred to as component (B')) that does not have a hydroxy group, other than components (B1) and (B2).

[0042] Examples of the component (B') include mono(meth)acrylates having an alkyl group having 5 or less carbon atoms, such as methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, s-butyl(meth)acrylate, t-butyl(meth)acrylate, and n-pentyl(meth)acrylate; Examples include aromatic mono(meth)acrylates such as phenyl(meth)acrylate, benzyl acrylate, 2-phenylethyl(meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0043] The content of the component (B') is preferably 30% by mass or less, and more preferably 10% by mass or less, relative to 100% by mass of the total of the components (A), (B), and (C).

[0044] The component (C) is a mono(meth)acrylate having a hydroxy group, and is a component that allows the cured product layer to exhibit excellent resistance to wet heat whitening.

[0045] Examples of the component (C) include aliphatic mono(meth)acrylates having one primary hydroxy group, such as 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 5-hydroxypentyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 7-hydroxyheptyl(meth)acrylate, and 8-hydroxyoctyl(meth)acrylate; aliphatic mono(meth)acrylates having one secondary hydroxy group, such as 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 3-hydroxybutyl(meth)acrylate, 4-hydroxyhexyl(meth)acrylate, and 5-hydroxyhexyl(meth)acrylate; aliphatic mono(meth)acrylates having two hydroxy groups, such as 2,3-dihydroxypropyl (meth)acrylate, 3,4-dihydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, and 1,4-dihydroxyheptyl (meth)acrylate; alicyclic mono(meth)acrylates having one hydroxy group, such as 4-hydroxycyclohexyl(meth)acrylate and 3-hydroxy-1-adamantyl(meth)acrylate; Alicyclic mono(meth)acrylates having two hydroxy groups, such as 1,4-cyclohexanedimethanol mono(meth)acrylate and 3,5-dihydroxyadamantyl (meth)acrylate; Examples include aromatic (meth)acrylates having one hydroxy group such as 2-hydroxy-3-phenoxypropyl (meth)acrylate, which may be used alone or in combination of two or more.

[0046] Among these, (meth)acrylates having one primary hydroxy group are preferred, and 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are more preferred, as the cured product layer is likely to exhibit excellent resistance to wet heat whitening.

[0047] When the total of components (A), (B), and (C) is taken as 100% by mass, the content of component (C) is 10 to 35% by mass. If the content of component (C) is less than 10% by mass, the initial adhesive strength and resistance to wet heat whitening of the cured material layer tend to deteriorate, while if it exceeds 35% by mass, the adhesive strength of the cured material layer tends to decrease initially and after exposure to high temperatures. From the same viewpoint, the content of component (C) is preferably 15 to 30% by mass, more preferably 15 to 25% by mass.

[0048] The pressure-sensitive adhesive composition of the present invention may contain a tackifier resin (D) (hereinafter referred to as component (D)) because the cured product layer is likely to exhibit high adhesive strength both initially and after exposure to high temperatures.

[0049] Examples of component (D) include rosin resins, aliphatic petroleum resins, aromatic petroleum resins, phenolic resins, styrene resins, xylene resins, coumarone-indene resins, terpene resins, terpene phenolic resins, aromatic modified terpene resins, and hydrogenated versions of these resins. These may be used alone or in combination of two or more.

[0050] Commercially available products of component (D) include, for example, "Pensel D-135," "Super Ester A-125," "Pine Crystal KE-100," "Pine Crystal KE-311," "Pine Crystal KE-604," "Alcon P-100," "Alcon M-100," "Alcon M-135," and "Alcon P-140" (manufactured by Arakawa Chemical Industries, Ltd.), "YS Polystar K125," "YS Polystar N125," "YS Polystar TH130," "YS Polystar G150," and "YS Polystar T-160" (all manufactured by Yasuhara Chemical Co., Ltd.), and "FTR0100," "FTR0120," "FTR2085," "FTR2120," "FTR2140," "FTR6100," "FTR6110," and "FTR6125" (all manufactured by Mitsui Chemicals, Inc.).

[0051] The content of the (D) component relative to 100% by mass of the total of the (A), (B), and (C) components is preferably 10% by mass or less, and more preferably 5% by mass or less, because the cured product layer exhibits high adhesive strength both initially and after exposure to high temperatures and is likely to have excellent resistance to wet heat whitening.

[0052] The pressure-sensitive adhesive composition of the present invention may further contain a polyfunctional monomer. Examples thereof include (meth)acrylates such as hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and urethane (meth)acrylate. These may be used alone or in combination of two or more. The content of the polyfunctional monomer is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the pressure-sensitive adhesive composition according to the present invention.

[0053] The pressure-sensitive adhesive composition of the present invention may contain various known additives as needed. The additives are not particularly limited, and examples thereof include surface conditioners, surfactants, UV absorbers, antioxidants, light stabilizers, inorganic fillers, silane coupling agents, colloidal silica, antifoaming agents, wetting agents, and rust inhibitors. These may be used alone or in combination of two or more.

[0054] The pressure-sensitive adhesive composition of the present invention can be obtained by mixing components (A), (B), and (C), and optionally components (B'), (D), the polyfunctional monomer, and additives. The mixing method and order are not particularly limited. Furthermore, when component (A) is diluted with component (B), the resulting solution can be mixed with component (C), and optionally components (B'), (D), the polyfunctional monomer, and additives.

[0055] The pressure-sensitive adhesive composition of the present invention is substantially solvent-free, but may contain an organic solvent as long as the content is less than 1 mass %, preferably less than 0.1 mass %. The organic solvent here includes, for example, aromatic hydrocarbons such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha; aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, isooctane, and n-decane; alicyclic hydrocarbons such as cyclohexane; esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate; acetone, methyl ethyl ketone, and the like. Examples of the alcohol include ketones such as ethylene glycol monomethyl ether, methyl isobutyl ketone, isophorone, cyclohexanone, and methylcyclohexanone; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; and alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, s-butanol, and t-butanol.

[0056] The pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator when irradiated with active energy rays.

[0057] Examples of the photopolymerization initiator include: hydroxyketones such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (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, and 2-isopropoxy-2-phenylacetophenone; acylphosphine oxides such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-2-(o-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(o-acetyloxime); Aminoketones such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropiophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, and 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butan-1-one; Bis(η 5 Cationic photopolymerization initiators such as (2,4-cyclopentadien-1-yl)-bis{2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl}titanium, 4-isobutylphenyl(4-methylphenyl)iodonium hexafluorophosphate, sulfonium hexafluorophosphate, and sulfonium tetrakis(pentafluorophenyl)borate; Benzil ketals such as 2,2-dimethoxy-2-phenylacetophenone (2,2-dimethoxy-1,2-diphenylethan-1-one); benzophenones such as benzophenone, 4-methylbenzophenone, benzophenone 2-carboxylate methyl (methyl 2-benzoylbenzoate), and 4,4-bis(dimethylamino)benzophenone; thioxanthones such as 2,4-diethylthioxanthone and 2-isopropylthioxanthone; Examples include oxyacetic acid esters such as oxyphenylacetic acid 2-(2-oxo-2-phenylacetoxyethoxy)ethyl ester and oxyphenylacetic acid 2-(2-hydroxyethoxy)ethyl ester; methyl benzoyl formate (methyl oxophenylacetate, 1-methoxy-2-phenyl-1,2-ethanedione, phenylglyoxylic acid methyl ester), etc. These may be used alone or in combination of two or more.

[0058] The content of the photopolymerization initiator relative to the total of the components (A), (B), and (C) (100% by mass) is preferably 0.05 to 10% by mass, and more preferably 0.2 to 5% by mass.

[0059] The cured product of the present invention is obtained by curing the pressure-sensitive adhesive composition.

[0060] The cured product of the present invention can be obtained by applying the pressure-sensitive adhesive composition to a substrate and then irradiating the substrate with active energy rays. Alternatively, the composition may be dried under heating before being irradiated with active energy rays.

[0061] Examples of the substrate include plastic and paper.

[0062] Examples of plastics include olefin resins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, and cycloolefin; Polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene terephthalate (PBT), polybutylene adipate terephthalate (PBAT), polylactic acid, polyhydroxyalkanoic acid, and polycaprolactone; (Meth)acrylic resins such as polymethyl (meth)acrylate; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and poly(ethylene-vinyl acetate); styrene resins such as polystyrene, poly(styrene-acrylonitrile) (AS resin), and poly(styrene-butadiene-acrylonitrile) (ABS resin); Examples of the resin include polycarbonate, polyether ether ketone, polyamide, polyimide, epoxy resin, melamine resin, diacetyl cellulose, triacetyl cellulose, and fluororesin.

[0063] Examples of paper include bleached kraft paper, unbleached kraft paper, fine paper, medium-quality paper, lightly coated paper, coated paper, processed base paper, paperboard, white paperboard, liner, semi-glassine paper, glassine paper, parchment paper, and top-coated paper.

[0064] Other substrates that can be used include, for example, fabrics such as woven fabrics and nonwoven fabrics; foam sheets such as foamed polyurethane and foamed polychloroprene rubber; rubbers such as natural rubber and butyl rubber; metals such as aluminum and copper; glass, ITO, and the like.

[0065] Furthermore, as the substrate, these crosslinked films or laminated films may be used, and any of untreated films, films that have been subjected to light to heavy release treatment, and films that have an easy-adhesion layer or anchor layer may be used.

[0066] Examples of the coating method include an applicator, a bar coater, a Mayer bar coater, a roll coater, a die coater, a comma coater, a knife coater, a gravure coater, a reverse gravure coater, offset printing, flexographic printing, screen printing, etc. The amount of the active energy ray-curable pressure-sensitive adhesive composition to be applied is such that the thickness of the cured product layer is preferably 25 to 1000 μm, more preferably 100 to 500 μm.

[0067] Examples of active energy rays include light rays such as ultraviolet rays, infrared rays, and visible light rays, as well as electron beams, X-rays, α rays, β rays, γ rays, and neutron rays. In the present invention, light rays are preferred, and ultraviolet rays are more preferred.

[0068] Examples of ultraviolet light sources include xenon lamps, high-pressure mercury lamps, metal halide lamps, UV-LEDs, etc. The irradiation intensity of ultraviolet light is usually 80 to 160 mW / cm. 2 The cumulative light intensity is usually 100 to 3000 mJ / cm 2 The conveying speed is usually 5 to 50 m / min.

[0069] The laminate of the present invention has the cured product on at least one surface of a substrate. The substrate, coating method, irradiation conditions, etc. used are the same as those described above. [Example]

[0070] The present invention will be specifically described below through examples and comparative examples. However, it goes without saying that the technical scope of the present invention is not limited by these examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0071] Manufacturing Example 1 A reactor equipped with a condenser, a stirrer, and a nitrogen inlet tube was charged with 89.7 parts of polytetramethylene glycol (trade name: "PTMG2000" manufactured by Mitsubishi Chemical Corporation) (hereinafter referred to as PTMG2000), 9.2 parts of isophorone diisocyanate (hereinafter referred to as IPDI), 0.1 parts of methoquinone (hereinafter referred to as MQ), and 0.1 parts of stannous octoate. The mixture was heated to 70 ° C. and maintained at this temperature for 3 hours. 1.1 parts of 2-isocyanatoethyl methacrylate (trade name: "Karenz MOI" manufactured by Showa Denko K.K.) (hereinafter referred to as Karenz MOI) was then added. The mixture was maintained at 70 ° C. for 2 hours, and the NCO value was measured to confirm the completion of the reaction, yielding a urethane methacrylate (A-1) having a weight average molecular weight of 60,000. The NCO value was measured in accordance with JIS K 1603-1 (the same applies hereinafter).

[0072] Manufacturing Example 2 To a reaction apparatus similar to that used in Production Example 1, 91.8 parts of PTMG2000, 7.1 parts of hexamethylene diisocyanate, 0.1 parts of MQ, and 0.1 parts of stannous octoate were added, and the mixture was heated to 70°C and maintained at that temperature for 3 hours. After that, 1.1 parts of Karenz MOI was added, and the mixture was maintained at 70°C for 2 hours. The NCO value was measured to confirm the completion of the reaction, thereby obtaining a urethane methacrylate (A-2) having a weight average molecular weight of 60,000.

[0073] Manufacturing Example 3 92.9 parts of polytetramethylene glycol (trade name: "PTMG3000", manufactured by Mitsubishi Chemical Corporation) (hereinafter referred to as PTMG3000), 6.4 parts of IPDI, 0.1 part of MQ, and 0.1 part of stannous octoate were added, the temperature was raised to 70°C, and the mixture was kept at that temperature for 3 hours. After that, 0.7 parts of Karenz MOI was added, and the mixture was kept at 70°C for 2 hours. The NCO value was measured to confirm the completion of the reaction, thereby obtaining a urethane methacrylate (A-3) with a weight average molecular weight of 80,000.

[0074] Manufacturing Example 4 A reaction apparatus similar to that used in Production Example 1 was charged with 93.0 parts of PTMG3000, 6.4 parts of IPDI, 0.1 parts of MQ, and 0.1 parts of stannous octoate, and the mixture was heated to 70°C and maintained at that temperature for 3 hours. Thereafter, 0.7 parts of 2-isocyanatoethyl acrylate (trade name: Karenz AOI, manufactured by Showa Denko K.K.) was added, and the mixture was maintained at 70°C for 2 hours. The NCO value was measured to confirm completion of the reaction, yielding a urethane acrylate (A-4) having a weight-average molecular weight of 80,000.

[0075] Comparative Manufacturing Example 1 To a reaction apparatus similar to that used in Production Example 1, 88.4 parts of polypropylene glycol (trade name: "ADEKA POLYETHER P-2000", number average molecular weight: 2000, manufactured by ADEKA Corporation) (hereinafter referred to as P-2000), 10.6 parts of IPDI, 0.1 parts of MQ, and 0.1 parts of stannous octoate were added, the mixture was heated to 70°C, and maintained at that temperature for 3 hours. After that, 1.0 part of 4-hydroxybutyl acrylate (4HBA) was added, and the mixture was maintained at 70°C for 2 hours. The NCO value was measured to confirm completion of the reaction, yielding a urethane acrylate (A'-1) with a weight average molecular weight of 60,000.

[0076] Comparative Manufacturing Example 2 A reaction apparatus similar to that used in Production Example 1 was charged with 84.3 parts of PTMG2000, 12.5 parts of IPDI, 0.1 parts of MQ, and 0.1 parts of stannous octoate, and the mixture was heated to 70°C and maintained at that temperature for 3 hours. After that, 3.3 parts of 2-hydroxyethyl acrylate (2HEA) was added and the mixture was maintained at 70°C for 2 hours. The NCO value was measured to confirm completion of the reaction, yielding a urethane acrylate (A'-2) with a weight-average molecular weight of 35,000.

[0077] Comparative Manufacturing Example 3 To a reaction apparatus similar to that used in Production Example 1, 98.5 parts of polypropylene glycol (trade name: "Preminol S4318F", number average molecular weight: 18,000, manufactured by AGC Corporation), 0.6 parts of IPDI, 0.1 parts of MQ, and 0.1 parts of stannous octoate were added, the temperature was raised to 70°C, and the mixture was maintained at this temperature for 3 hours. After that, 0.9 parts of Karenz MOI was added, and the mixture was maintained at 70°C for 2 hours. The NCO value was measured to confirm the completion of the reaction, thereby obtaining a urethane methacrylate (A'-3) having a weight average molecular weight of 90,000.

[0078] Comparative Manufacturing Example 4 To a reaction vessel similar to that used in Production Example 1, 88.5 parts of PTMG2000, 10.7 parts of IPDI, 0.1 parts of MQ, and 0.1 parts of stannous octoate were added, the temperature was raised to 70°C, and the temperature was maintained for 3 hours. After that, 0.8 parts of 2-hydroxyethyl acrylate (2HEA) was added, and the temperature was maintained at 70°C for 2 hours. The NCO value was measured to confirm the completion of the reaction, yielding a urethane acrylate (A'-4) with a weight-average molecular weight of 220,000. However, due to the high viscosity, the reaction mixture was not subjected to the following evaluations.

[0079] Example 1 Urethane methacrylate (A-1), 2-ethylhexyl acrylate as the (B1) component, isobornyl acrylate as the (B2) component, and 4-hydroxybutyl acrylate as the (C) component were mixed in the blending ratio shown in Table 1, and then 1 part of 1-hydroxycyclohexyl phenyl ketone (trade name: "LUNACURE200", manufactured by DKSH) was further mixed as a photopolymerization initiator to obtain an active energy ray-curable pressure-sensitive adhesive composition.

[0080] Examples 2 to 15, Comparative Examples 1 to 7 The same procedure as in Example 1 was carried out except that the compositions and content ratios were changed as shown in Table 1, and active energy ray-curable pressure-sensitive adhesive compositions were obtained.

[0081] <Preparation of pre-laminate> The pressure-sensitive adhesive composition of each Example and Comparative Example was applied to a 75 μm thick polyester film treated with a heavy release agent (product name: "SP-PET-03-75BU", manufactured by Panac Corporation) so that the film thickness after curing would be 400 μm, and the release-treated surface of a 38 μm thick polyester film treated with a light release agent (product name: "SP-PET-01-38BU", manufactured by Panac Corporation) was bonded to the coated layer. Next, in the atmosphere, a high-pressure mercury lamp (100 mW / cm 2 , 900mJ / cm 2 ) to produce a pre-laminate (light release treated polyester film / cured product / heavy release treated polyester film).

[0082] <Heat yellowing resistance> The light release treated polyester film was peeled off from the pre-laminate and the laminate was instead attached to glass with a 2 kg roller, and then the heavy release treated polyester film was peeled off and the laminate was attached to the glass, followed by autoclave treatment at 70°C and 0.5 MPa for 30 minutes to obtain a double-sided glass laminate (glass / cured product / glass). The obtained laminate was measured for the initial color difference (b * The value of b * The value is the b of the substrate (glass plate) * The results are shown in Table 1 (same below). b * A value of 1 or less indicates good initial color difference, and the closer the value is to 0, the better. Next, the laminate was left to stand in a thermo-hygrostat at a temperature of 120°C for 500 hours, and then the color difference (b * value) and measure the initial color difference (b * The change from the value (△b * ) was calculated and the heat yellowing resistance was evaluated according to the following criteria.

[0083] (Evaluation criteria) A: Color difference (b * The change from the value is less than 0.5. B: Color difference (b* The change from the value is 0.5 or more and less than 1. C: Color difference (b * The change from the value is 1 or more.

[0084] <Moisture and heat resistance (whitening and peeling)> The light release treated polyester film was peeled off from the pre-laminate and the laminate was instead attached to glass with a 2 kg roller, and then the heavy release treated polyester film was peeled off and the laminate was attached to the glass, followed by autoclave treatment at 70°C and 0.5 MPa for 30 minutes to obtain a double-sided glass laminate (glass / cured product / glass). The resulting laminate was allowed to stand in a thermo-hygrostat at a temperature of 85°C and a humidity of 85% for 500 hours, and then the whitening and peeling of the cured product were visually inspected and evaluated according to the following criteria.

[0085] (Evaluation criteria) A: No whitening or peeling B: No whitening, but part of the base material peeled off C: Whitening occurred and the base material was completely peeled off.

[0086] <Adhesive strength> The light release treated polyester film was peeled off from the pre-laminate and replaced with a 50 μm thick polyester film (product name: "Cosmoshine A-4300", manufactured by Toyobo Co., Ltd.) with a 2 kg roller and left for 2 hours. Next, a 2.5 cm × 8 cm test piece was cut from this and the heavy release treated polyester film was peeled off to obtain a single-sided PSA sheet (Cosmoshine A-4300 / cured product). The laminate was attached to a glass plate using a 2 kg roller and left for 24 hours at 25°C and 50% humidity to produce a laminate (Cosmoshine A-4300 / cured product / glass). Using a commercially available testing machine (trade name: "Tensilon Universal Material Tester," manufactured by A&D Co., Ltd.), the glass plate was peeled off in a 180° direction at a rate of 300 mm / min to measure the adhesive strength (N / 25 mm) of the cured product. The laminate was also placed in a thermo-hygrostat at 85°C for at least 2 hours, after which the high-temperature adhesive strength of the laminate was measured in the same manner. A value of 20 N / mm or greater at 25°C and 5 N / 25 mm or greater at 85°C indicates good adhesive strength, with higher values ​​indicating better adhesive strength.

[0087] [Table 1] *1: Expressed as a ratio when the total of components (A), (B), and (C) is 100% by mass. *2: Shown as a ratio to 100% by mass of the total of components (A), (B), and (C).

[0088] The symbols in Table 1 represent the following compounds: <Urethane (meth)acrylate> A-1: Urethane methacrylate of Production Example 1 A-2: Urethane methacrylate of Production Example 2 A-3: Urethane methacrylate of Production Example 3 A-4: Urethane acrylate of Production Example 4 A'-1: Urethane acrylate of Comparative Preparation Example 1 A'-2: Urethane acrylate of Comparative Production Example 2 A'-3: Urethane methacrylate of Comparative Production Example 3 <(B1) component> 2EHA: 2-Ethylhexyl acrylate NOAA: n-octyl acrylate ·LA: Lauryl acrylate ISTA: Isostearyl acrylate <(B2) component> IBXA: Isobornyl acrylate FA-513AS: Dicyclopentanyl acrylate, product name: "FA-513AS", manufactured by Resonac Co., Ltd. <(C) component> 4HBA: 4-hydroxybutyl acrylate 2HEA: 2-hydroxyethyl acrylate <Tackifying resin> D-1: Styrene resin (product name: "FTR6125", styrene-aliphatic monomer copolymer, manufactured by Mitsui Chemicals, Inc.)

Claims

1. a urethane(meth)acrylate (A) having a weight average molecular weight of 50,000 to 200,000, which is a reaction product of a linear polyether polyol (a1) having an alkylene chain having 4 or more carbon atoms as a repeating unit, a polyisocyanate (a2), and a mono(meth)acrylate (a3-1) having a hydroxy group or a mono(meth)acrylate (a3-2) having an isocyanate group; a mono(meth)acrylate (B) having no hydroxy group, and Contains a mono(meth)acrylate (C) having a hydroxy group, the component (B) is an alkyl mono(meth)acrylate (B1) having an alkyl group having 6 to 20 carbon atoms and a cycloalkyl mono(meth)acrylate (B2), the ratio of the mass of nonvolatile matter of the component (B1) to the mass of the component (B2) [(B1) / (B2)] is 0.05 or more and less than 1; An active energy ray-curable pressure-sensitive adhesive composition, wherein the content of component (C) is 10 to 35 mass% when the total of components (A), (B), and (C) is 100 mass%.

2. The active energy ray-curable pressure-sensitive adhesive composition according to claim 1, further comprising a tackifier resin (D).

3. A cured product of the active energy ray-curable pressure-sensitive adhesive composition according to claim 1 or 2.

4. A laminate having the cured product according to claim 3 on at least one surface of a substrate.

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