Composition

Abstract

The present invention provides a composition that exhibits excellent adhesion to various substrates, preferably plastic films, as well as excellent impact resistance after curing, and furthermore, excellent coating properties. [Solution] A composition comprising a monofunctional ethylenically unsaturated compound (A) having an aryl group and a urethane (meth)acrylate compound (B), wherein the urethane (meth)acrylate compound (B) has a polyester structure and a weight-average molecular weight of 1,000 to 20,000, and the mass content ratio of the monofunctional ethylenically unsaturated compound (A) having an aryl group to the urethane (meth)acrylate compound (B) is (A):(B)=80:20 to 20:80.

Description

[Technical Field]

[0001] The present invention relates to a composition that can bond various substrates, preferably plastic films, by irradiation with active energy rays such as electron beams or ultraviolet rays, and further exhibits excellent impact resistance. [Background technology]

[0002] Traditionally, glass substrates were used for optical components such as touch panels and optical recording media, as transparent substrates were required. However, in recent years, highly transparent plastics have become widely used as a substitute for glass due to their impact resistance and lightweight properties. Furthermore, for optical components, the adhesives used are increasingly required to be flexible in terms of design and safety. Therefore, in addition to adhesive strength, the adhesives are also required to have high elongation properties.

[0003] It is known that adhesives made of urethane (meth)acrylate compounds can be used as adhesives for optical components that require such physical properties. For example, Patent Document 1 discloses a (meth)acrylate adhesive composition containing a (meth)acrylate monomer, a urethane-based (meth)acrylate oligomer, and one selected from acrylamide derivatives, silane compounds, and organophosphorus compounds. It has been shown that polycarbonate resin laminates made using this (meth)acrylate adhesive composition exhibit excellent transparency, adhesive strength, heat resistance, moisture resistance, and bendability.

[0004] Furthermore, Patent Document 2 discloses an active energy ray-curable adhesive composition for polycarbonate-based materials containing acryloylmorpholine and a urethane (meth)acrylate compound having a carbonate structure. It has been shown that this active energy ray-curable adhesive composition for polycarbonate-based materials can produce an adhesive layer that exhibits excellent adhesion to polycarbonate resin and also has excellent hardness after curing.

[0005] Furthermore, cured products (adhesives) obtained by curing compositions that harden with active energy rays are required to mitigate external impacts and minimize their influence on optical components. However, if the elastic modulus of the adhesive is too high, there is a problem in that its impact resistance decreases. To improve the elastic modulus of such adhesives, for example, Patent Document 3 describes the study of rosin-based compounds and petroleum resin-based plasticizers. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-274256 [Patent Document 2] Japanese Patent Publication No. 2017-214550 [Patent Document 3] Japanese Patent Publication No. 2013-14718 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the technologies disclosed in Patent Documents 1 to 3 do not exhibit sufficient adhesion, particularly to various plastic films, and further improvements are needed. Furthermore, the technologies disclosed in Patent Documents 1 to 3 also lack sufficient impact resistance, and further improvements are needed.

[0008] Therefore, against this background, the present invention aims to provide a composition that exhibits excellent adhesion to various substrates, particularly various plastic films, as well as excellent impact resistance after curing, and furthermore, excellent coating properties. [Means for solving the problem]

[0009] However, in view of these circumstances, the present inventors conducted extensive research and found that the aforementioned problems can be solved by using a monofunctional unsaturated compound having an aryl group and a urethane (meth)acrylate compound having a specific weight-average molecular weight and polyester structure in combination in a specific mass content ratio as an active energy ray curable monomer, thus completing the present invention.

[0010] In other words, the present invention has the following aspects. [1] A composition comprising a monofunctional ethylenically unsaturated compound having an aryl group (A) and a urethane (meth)acrylate compound (B), The urethane (meth)acrylate compound (B) has a polyester structure and a weight-average molecular weight of 1,000 to 50,000. A composition in which the mass content ratio of the monofunctional ethylenically unsaturated compound (A) having an aryl group and the urethane (meth)acrylate compound (B) is (A):(B) = 80:20 to 20:80. [2] The composition according to [1] further comprising a photopolymerization initiator (C). [3] The composition according to [1] or [2], wherein the urethane (meth)acrylate compound (B) is a reaction product of a polyvalent isocyanate compound (b1), a polyester polyol (b2-1), and a hydroxyl group-containing (meth)acrylate compound (b3). [4] The composition according to [3], wherein the polyester polyol (b2-1) is a polyester polyol having a number average molecular weight of 60 to 20,000. [5] The composition according to [3] or [4], wherein the hydroxyl group-containing (meth)acrylate compound (b3) is a hydroxyl group-containing (meth)acrylate compound having one ethylenically unsaturated group. [Effects of the Invention]

[0011] The composition of the present invention exhibits excellent adhesion to various substrates, particularly various plastic films, as well as excellent impact resistance after curing, and furthermore, excellent coating properties. [Modes for carrying out the invention]

[0012] Hereinafter, the present invention will be described based on examples of modes for carrying out the present invention. However, the present invention is not limited to the embodiments described below.

[0013] In the present specification, the expression "x and / or y, wherein x and y are arbitrary components" means at least one of x and y, and covers three cases: only x, only y, and both x and y. In the present specification, when the expression "X to Y, wherein X and Y are arbitrary numerical values" is used, unless otherwise specified, it means "not less than X and not more than Y", and also includes the meaning of "preferably more than X" or "preferably less than Y". In the present specification, when the expression "not less than X, wherein X is an arbitrary numerical value" or "not more than Y, wherein Y is an arbitrary numerical value" is used, it also includes the meaning of "preferably more than X" or "preferably less than Y". Regarding the numerical ranges described stepwise in the present specification, the upper limit or lower limit of the numerical range at one step can be arbitrarily combined with the upper limit or lower limit of the numerical range at another step. Further, in the numerical ranges described in the present specification, the upper limit or lower limit of the numerical range can also be replaced with the values shown in the examples.

[0014] In the present specification, "(meth)acryl" means acryl and / or methacryl, "(meth)acryloyl" means acryloyl and / or methacryloyl, and "(meth)acrylate" means acrylate and / or methacrylate, respectively. In the present specification, the term "film" also includes "tape" and "sheet".

[0015] A composition according to an embodiment of the present invention (hereinafter referred to as "the present composition") contains a monofunctional ethylenically unsaturated compound (A) having an aryl group, and a urethane (meth)acrylate-based compound (B). The present composition is cured upon irradiation with an active energy ray, and can be used as an adhesive. That is, the present composition can be suitably used as an active energy ray-curable adhesive composition. Each component is described below.

[0016] [Monofunctional ethylenically unsaturated compound (A) having an aryl group] Examples of the aryl group contained in the monofunctional ethylenically unsaturated compound (A) having an aryl group (hereinafter referred to as "unsaturated compound (A)") include monocyclic aryl groups, bicyclic aryl groups, and aryl groups having three or more rings. Examples of the monocyclic aryl group include a phenyl group. Examples of the bicyclic aryl group include a naphthyl group and a biphenyl group. Examples of the aryl group having three or more rings include a fluorene ring structure and an anthracene ring structure. Specific examples thereof include styrenic unsaturated compounds such as styrene, vinyltoluene, chlorostyrene, and α-methylstyrene; phenoxyalkyl (meth)acrylates such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxypropyl (meth)acrylate; phenoxydialkylene glycol (meth)acrylates such as phenoxydiethylene glycol (meth)acrylate and phenoxydipropylene glycol (meth)acrylate; and monofunctional (meth)acrylates having an aryl group such as phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol (meth)acrylate, (meth)acrylate of an adduct of p-cumylphenol with an alkylene oxide, (meth)acrylate of an adduct of o-phenylphenol with an alkylene oxide, (meth)acrylate of an adduct of phenol with an alkylene oxide, and (meth)acrylate of an adduct of nonylphenol with an alkylene oxide. These may be used alone or in combination of two or more thereof. Among these, monofunctional (meth)acrylates having an aryl group are preferred, and phenoxydialkylene glycol (meth)acrylate is more preferred in terms of its excellent impact resistance after curing, and phenoxydiethylene glycol (meth)acrylate is particularly preferred.

[0017] The content of unsaturated compound (A) in this composition is usually 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more. The upper limit is usually 99% by mass or less, preferably 90% by mass or less, and more preferably 85% by mass or less.

[0018] [Urethane (meth)acrylate compound (B)] The urethane (meth)acrylate compound (B) has a polyester structure and can be obtained, for example, by reacting a polyvalent isocyanate compound (b1), a polyol (b2), and a hydroxyl group-containing (meth)acrylate compound (b3). In particular, for the urethane (meth)acrylate compound (B), it is preferable that the polyester structure is derived from polyol (b2) in order to have excellent impact resistance after curing. In other words, the urethane (meth)acrylate compound (B) is preferably a reaction product of a polyvalent isocyanate compound (b1), a polyester polyol (b2-1), and a hydroxyl group-containing (meth)acrylate compound (b3).

[0019] [Polyvalent isocyanate compounds (b1)] Examples of the polyvalent isocyanate compound (b1) include aromatic polyisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; pentamethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. Examples include aliphatic polyisocyanates such as lysine diisocyanate and lysine triisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, 1,3-bis(isocyanato)cyclohexane, 1,4-bis(isocyanato)cyclohexane, norbornene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate, or trimer compounds or polymer compounds of these polyisocyanates; allophanate-type polyisocyanates, biuret-type polyisocyanates, etc. These may be used individually or in combination of two or more.

[0020] Among these, aliphatic diisocyanates and alicyclic diisocyanates are preferred because they cause less yellowing, isophorone diisocyanate, 1,3-bis(isocyanato)cyclohexane, and 4,4'-dicyclohexylmethane diisocyanate are more preferred because they offer excellent reactivity and versatility, and 1,3-bis(isocyanato)cyclohexane is particularly preferred because it does not result in an excessively high modulus of elasticity and offers excellent impact resistance.

[0021] [Polyol (b2)] The polyol (b2) preferably includes a polyester polyol (b2-1) having a polyester structure.

[0022] Examples of the polyester polyol (b2-1) include condensation polymers of polyhydric alcohols and polyhydric carboxylic acids; ring-opening polymers of cyclic esters (lactones); and reaction products of three components: polyhydric alcohols, polyhydric carboxylic acids, and cyclic esters.

[0023] Examples of the aforementioned polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), sugar alcohols (such as xylitol and sorbitol), and the like. Examples of the polycarboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid. Examples of the cyclic esters mentioned above include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

[0024] The number of hydroxyl groups in the polyester polyol (b2-1) is preferably 2 to 6, more preferably 2 to 4, and particularly preferably 2.

[0025] The hydroxyl value of the polyester polyol (b2-1) is typically 10 to 500 mg KOH / g, preferably 20 to 300 mg KOH / g, and more preferably 40 to 200 mg KOH / g. When the hydroxyl value of the polyester polyol (b2-1) is within the above range, it tends to exhibit excellent flexibility.

[0026] The number-average molecular weight of the polyester polyol (b2-1) is preferably 60 to 20,000, more preferably 100 to 15,000, and even more preferably 200 to 10,000. When the number-average molecular weight of the polyester polyol (b2-1) is within the above range, it tends to have excellent flexibility. The number-average molecular weight of the polyester polyol (b2-1) can be calculated from the hydroxyl value.

[0027] The aforementioned polyol (b2) may include polyols other than polyester polyol (b2-1) (b2-2) [hereinafter sometimes referred to as "other polyols (b2-2)"]. Examples of the other polyols (b2-2) mentioned above include aliphatic polyols, alicyclic polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, and polysiloxane polyols. These can be used individually or in combination of two or more.

[0028] Examples of the aliphatic polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, 1 Examples include aliphatic alcohols containing two hydroxyl groups, such as 6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1,9-nonanediol, and 2-methyl-1,8-octanediol; sugar alcohols such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups, such as glycerin, trimethylolpropane, and trimethylolethane.

[0029] Examples of the alicyclic polyols include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecanedimethanol.

[0030] Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, as well as random or block copolymers of these polyalkylene glycols.

[0031] Examples of the polycarbonate polyol include reaction products of polyhydric alcohols and phosgene; and ring-opening polymers of cyclic carbonate esters (such as alkylene carbonates). Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polyester polyol. Examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate. The polycarbonate polyol can be any compound having a carbonate bond within its molecule and a hydroxyl group at its terminus, and may also have ester bonds in addition to the carbonate bond.

[0032] Examples of the aforementioned polyolefin polyols include those having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon backbone, and having hydroxyl groups at the molecular ends.

[0033] Examples of the polybutadiene polyol include those having a butadiene copolymer as the hydrocarbon backbone and having hydroxyl groups at the molecular ends. The polybutadiene polyol may also be a hydrogenated polybutadiene polyol in which all or part of the ethylenically unsaturated groups contained in its structure are hydrogenated.

[0034] Examples of the (meth)acrylic polyol include polymers or copolymers of (meth)acrylic acid esters that have at least two hydroxyl groups in the molecule. Examples of such (meth)acrylic acid esters include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0035] Examples of the polysiloxane polyols include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

[0036] Among these other polyols (b2-2), aliphatic polyols are preferred, more preferably aliphatic alcohols containing two hydroxyl groups, and particularly preferably neopentyl glycol.

[0037] When the polyester polyol (b2-1) and other polyols (b2-2) are used in combination, the molar content ratio is preferably (b2-1):(b2-2) = 10:90 to 90:10, more preferably 15:85 to 50:50, and even more preferably 20:80 to 40:60.

[0038] [Hydroxyl group-containing (meth)acrylate compound (b3)] Examples of the hydroxyl group-containing (meth)acrylate compound (b3) include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol (meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 2-hydroxy-3-(meth)acryloyloxyethyl Examples include hydroxyl group-containing (meth)acrylate compounds containing one ethylenically unsaturated group, such as ropyl (meth)acrylate; hydroxyl group-containing (meth)acrylate compounds containing two ethylenically unsaturated groups, such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyloxypropyl methacrylate; and hydroxyl group-containing (meth)acrylate compounds containing three or more ethylenically unsaturated groups, such as pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate. These may be used individually or in combination of two or more.

[0039] Among these, hydroxyl group-containing (meth)acrylate compounds having one ethylenically unsaturated group are preferred in that they offer a good balance between adhesion to the substrate and hardness when used as an adhesive layer. Hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate are more preferred, and 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are even more preferred in that they offer excellent reactivity and versatility.

[0040] The urethane (meth)acrylate compound (B) is obtained by reacting a polyvalent isocyanate compound (b1), a polyol (b2), and a hydroxyl group-containing (meth)acrylate compound (b3). It can be produced according to known methods.

[0041] A specific method for producing the aforementioned urethane (meth)acrylate compound (B) is, for example, (1) A method of charging a polyvalent isocyanate compound (b1), a polyol (b2), and a hydroxyl group-containing (meth)acrylate compound (b3) into a reactor together or separately and carrying out the reaction. (2) A method of reacting a hydroxyl group-containing (meth)acrylate compound (b3) with an intermediate reaction product obtained by pre-reacting a polyvalent isocyanate compound (b1) with a polyol (b2), (3) A method of reacting a polyol (b2) with an intermediate reaction product obtained by first reacting a polyvalent isocyanate compound (b1) with a hydroxyl group-containing (meth)acrylate compound (b3), While these are some examples, method (2) is preferred in terms of reaction stability and reduction of by-products.

[0042] In the method described in (2) above, known reaction methods can be used for the reaction between the polyvalent isocyanate compound (b1) and the polyol (b2). In this case, for example, by setting the molar ratio [isocyanate group:hydroxyl group] of the isocyanate group in the polyvalent isocyanate compound (b1) to the hydroxyl group in the polyol (b2) to approximately 2n:(2n-2) [where n is an integer of 2 or more], a terminal isocyanate group-containing urethane (meth)acrylate compound (hereinafter sometimes referred to as an "intermediate reaction product") can be obtained, and an addition reaction between the isocyanate group remaining at the end of this compound and the hydroxyl group-containing (meth)acrylate compound (b3) becomes possible.

[0043] In the aforementioned molar ratio, n is usually 4 or more, preferably 5 or more, and more preferably 6 or more. The upper limit is usually 10 or less, preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less. When n is within the above range, adhesion is excellent and handling tends to improve.

[0044] The addition reaction between the aforementioned intermediate reaction product and the hydroxyl group-containing (meth)acrylate compound (b3) can be carried out using known reaction methods.

[0045] The reaction molar ratio between the intermediate reaction product and the hydroxyl group-containing (meth)acrylate compound (b3) is, for example, approximately 1:2 if the intermediate reaction product has two isocyanate groups and the hydroxyl group-containing (meth)acrylate compound (b3) has one hydroxyl group, and approximately 1:3 if the intermediate reaction product has three isocyanate groups and the hydroxyl group-containing (meth)acrylate compound (b3) has one hydroxyl group.

[0046] In the addition reaction between the aforementioned intermediate reaction product and the hydroxyl group-containing (meth)acrylate compound (b3), the urethane (meth)acrylate compound (B) can be obtained by terminating the reaction when the remaining isocyanate groups in the reaction system become 0.5% by mass or less.

[0047] In the reaction between the polyvalent isocyanate compound (b1) and the polyol (b2), and further in the reaction between the intermediate reaction product and the hydroxyl group-containing (meth)acrylate compound (b3), it is also preferable to use a catalyst to accelerate the reaction. Examples of the catalysts include organometallic compounds such as tin octate, dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octote, tin octote, cobalt naphthenate, stannous chloride, and stannous chloride; amine catalysts such as triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, and N-ethylmorpholine; bismuth nitrate, bismuth bromide, bismuth iodide, and bismuth sulfide; as well as organobismuth compounds such as dibutylbismuth dilaurate and dioctylbismuth dilaurate; and 2-ethylhexyl Examples include bismuth-based catalysts such as bismuth phosphate, bismuth naphthenate, bismuth isodecanate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth lybisneodecanoate, bismuth disalicylate, bismuth digallate, and other organic acid bismuth salts; zirconium-based catalysts such as inorganic zirconium, organozirconium, and elemental zirconium; and combinations of two or more catalysts such as zinc 2-ethylhexanoate / zirconium tetraacetylacetonate. Among these, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferred. These may be used individually or in combination of two or more. Dibutyltin dilaurate is particularly preferred.

[0048] Furthermore, in the production of urethane (meth)acrylate compound (B), organic solvents that do not have functional groups that react with isocyanate groups can be used, such as esters like ethyl acetate and butyl acetate, ketones like methyl ethyl ketone and methyl isobutyl ketone, and aromatics like toluene and xylene.

[0049] The reaction temperature in the production of the urethane (meth)acrylate compound (B) is usually 30 to 90°C, preferably 40 to 80°C, and the reaction time is usually 2 to 12 hours, preferably 3 to 10 hours.

[0050] The weight-average molecular weight of the urethane (meth)acrylate compound (B) is 1,000 to 50,000, preferably 2,000 to 45,000, and particularly preferably 3,000 to 40,000. When the weight-average molecular weight is within the above range, it exhibits excellent adhesion to the adherend and flexibility after curing.

[0051] The aforementioned weight-average molecular weight is the weight-average molecular weight converted to the standard polystyrene molecular weight, and was obtained using a high-performance liquid chromatograph (Showa Denko Corporation, "Shodex GPC system-11") with a column (Shodex GPC KF-806L, exclusion limit molecular weight: 2 × 10⁻¹⁶). 7 Separation range: 100~2×10 7 The measurement is performed by using three tubes in series (theoretical plate count: 10,000 stages / tube, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm).

[0052] The viscosity of the urethane (meth)acrylate compound (B) is preferably 1,000 to 1,000,000 mPa·s at 60°C, particularly preferably 2,000 to 500,000 mPa·s, and even more preferably 3,000 to 100,000 mPa·s. When the viscosity is within the above range, it tends to have excellent coating properties. The viscosity can be measured using an E-type viscometer.

[0053] The content of the urethane (meth)acrylate compound (B) in this composition is usually 1 to 90% by mass, preferably 5 to 85% by mass, and more preferably 10 to 75% by mass.

[0054] Furthermore, the content ratio (mass ratio) of the unsaturated compound (A) and the urethane (meth)acrylate compound (B) is (A):(B) = 80:20 to 20:80, preferably 79:21 to 25:75, and more preferably 78:22 to 40:60. When the content ratio is within the above range, the adhesion to the adherend and the impact resistance after curing are excellent.

[0055] [Photopolymerization initiator (C)] This composition preferably contains a photopolymerization initiator (C) in order to efficiently cure using active energy rays.

[0056] The photopolymerization initiator (C) is not particularly limited as long as it generates radicals upon the action of light, for example, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy- Acetophenones such as 2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methyl-propan-1-one; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, o-benzo Benzophenones such as methyl ylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminonium bromide, (4-benzoylbenzyl)trimethylammonium chloride, etc.; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthio Examples include thioxanthones such as xanthones, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; and acyl phosphonate oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.These may be used individually or in combination of two or more types.

[0057] The content of the photopolymerization initiator (C) is usually 0.1 to 20 parts by mass, preferably 1 to 10 parts by mass, and more preferably 2 to 5 parts by mass, based on 100 parts by mass of the total of the unsaturated compound (A) and the urethane (meth)acrylate compound (B) [and if an ethylenically unsaturated compound (D) described later is included, the total including (D)]. When the content of the photopolymerization initiator (C) is within the above range, the adhesive strength is excellent and discoloration such as yellowing tends to be suppressed.

[0058] As auxiliary agents for these photopolymerization initiators (C), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. may be used in combination. These may be used individually or in combination of two or more.

[0059] [Ethylene-unsaturated compounds other than unsaturated compounds (A) (D)] Furthermore, this composition may also contain an ethylenically unsaturated compound (D) other than the unsaturated compound (A) and the urethane (meth)acrylate compound (B) [hereinafter referred to as "unsaturated compound (D)"]. Examples of the unsaturated compound (D) include monofunctional monomers, difunctional monomers, and monomers with three or more functions. These may be used individually or in combination of two or more.

[0060] The aforementioned monofunctional monomers are monomers containing one ethylenically unsaturated group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate Examples include lylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, glycidyl (meth)acrylate, trimethylolpropane (formal) (meth)acrylate, acrylonitrile, vinyl acetate, allyl (meth)acrylate, and 2-(meth)acryloyloxyethyl acid phosphate monoester.

[0061] Other examples of monofunctional monomers include Michael adducts of (meth)acrylic acid and 2-acryloyloxyethyl dicarboxylic acid monoesters. Examples of the Michael adducts of (meth)acrylic acid include (meth)acrylic acid dimers, (meth)acrylic acid trimers, and (meth)acrylic acid tetramers. The 2-acryloyloxyethyl dicarboxylic acid monoester is a carboxylic acid having a specific substituent, such as 2-acryloyloxyethyl succinate monoester, 2-methacryloyloxyethyl succinate monoester, 2-acryloyloxyethyl phthalate monoester, 2-methacryloyloxyethyl phthalate monoester, 2-acryloyloxyethyl hexahydrophthalate monoester, and 2-methacryloyloxyethyl hexahydrophthalate monoester. Furthermore, other oligoester acrylates can also be used as monofunctional monomers.

[0062] The aforementioned bifunctional monomer is a monomer containing two ethylenically unsaturated groups, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene Examples include bisphenol A type di(meth)acrylate modified with ammonium oxide, bisphenol A type di(meth)acrylate modified with propylene oxide, 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide modified di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diglycidyl phthalate di(meth)acrylate, hydroxypivalic acid modified neopentyl glycol di(meth)acrylate, and 2-(meth)acryloyloxyethyl acid phosphate diester.

[0063] The aforementioned monomers with three or more functions are monomers containing three or more ethylenically unsaturated groups, and examples include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, isocyanurate ethylene oxide-modified triacrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and caprolactone-modified pentaerythritol tetra(meth)acrylate.

[0064] Among these unsaturated compounds (D), monofunctional monomers are preferred in terms of their excellent flexibility of the coating film, and methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and butoxyethyl (meth)acrylate are more preferred in terms of less yellowing and excellent flexibility.

[0065] When this composition contains an unsaturated compound (D), its content is usually 70% by mass or less, preferably 50% by mass or less, and more preferably 30% by mass or less, relative to the total of the unsaturated compound (A), the urethane (meth)acrylate compound (B), and the unsaturated compound (D). When the content is within the above range, the composition tends to exhibit excellent adhesion to the adherend.

[0066] In addition to the unsaturated compound (A), urethane (meth)acrylate compound (B), photopolymerization initiator (C), and unsaturated compound (D), this composition may optionally contain resins such as acrylic resins and polyurethane compounds, or inorganic particles such as silica gel. Furthermore, the composition may contain antioxidants, flame retardants, antistatic agents, fillers, leveling agents, stabilizers, reinforcing agents, matting agents, crosslinking agents, etc., in a range that does not impair the effects of the present invention (for example, 10% by mass or less of the composition, preferably 5% by mass or less).

[0067] As the crosslinking agent, compounds that induce crosslinking by heat, specifically epoxy compounds, aziridine compounds, melamine compounds, isocyanate compounds, chelate compounds, etc., can be used.

[0068] Furthermore, this composition may contain polythiol compounds in terms of suppressing unreacted components and improving adhesive strength. The aforementioned polythiol compound is not particularly limited, but compounds having 2 to 6 mercapto groups in the molecule are preferred. Examples include aliphatic polythiols such as alkanedithiols with about 2 to 20 carbon atoms, aromatic polythiols such as xylylenedithiols, polythiols obtained by substituting halogen atoms of halohydrin adducts of alcohols with mercapto groups, polythiols consisting of hydrogen sulfide reaction products of polyepoxide compounds, and polythiols consisting of esters of polyhydric alcohols having 2 to 6 hydroxyl groups in the molecule with thioglycolic acid, β-mercaptopropionic acid, or β-mercaptobutanoic acid. These may be used individually or in combination of two or more.

[0069] If the composition contains a polythiol compound, its content is usually 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the total of the unsaturated compound (A) and the urethane (meth)acrylate compound (B) [and if the composition contains the unsaturated compound (D), the total including (D)].

[0070] Furthermore, while this composition may use a solvent to adjust the viscosity during coating as needed, it is preferable that it be a solvent-free adhesive composition that is substantially free of solvents, because solvent residue may remain in the adhesive layer and curing components may volatilize when the solvent dries. In this specification, "substantially solvent-free" means that the solvent is typically 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.1% by mass or less, relative to the composition.

[0071] This composition is obtained by mixing the unsaturated compound (A), the urethane (meth)acrylate compound (B), and optionally a photopolymerization initiator (C), an unsaturated compound (D), etc.

[0072] The viscosity of this composition at 25°C is preferably 100 to 50,000 mPa·s, more preferably 300 to 8,000 mPa·s, and even more preferably 500 to 6,000 mPa·s, from the viewpoint of coating properties and other factors. When the viscosity is within the above range, it tends to have excellent coating properties and adhesion. The viscosity is measured using an E-type viscometer.

[0073] This composition is cured by irradiation with active energy rays, for example, after being coated onto a substrate and then adhering an object to the coated surface, or after being coated onto an object and then adhering a substrate to the coated surface, to form an adhesive layer.

[0074] Examples of substrates to be coated with this composition include synthetic resins such as (meth)acrylic resins, polyolefin resins, polyester resins, polycarbonate resins, acrylonitrile butadiene styrene copolymers (ABS), polystyrene resins, and polyamide resins, as well as molded products thereof (films, sheets, cups, etc.), metal substrates (metal vapor-deposited layers, metal plates (copper, stainless steel (SUS304, SUSBA, etc.), aluminum, zinc, magnesium, etc.)), glass, and composite substrates thereof.

[0075] Examples of the adherends include articles having various metal surfaces; polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; synthetic resins such as polystyrene, polycarbonate, polyarylate, and polyimide, and molded products thereof (plates, films, sheets, cups, etc.).

[0076] In particular, this composition is useful as an adhesive composition for plastic films because it exhibits excellent adhesion to plastic films such as (meth)acrylic resins and polyimides.

[0077] The coating method for this composition is not particularly limited and includes, for example, wet coating methods such as spraying, showering, dipping, rolling, spinning, curtaining, flowing, slitting, die printing, gravure printing, comma printing, dispenser printing, screen printing, and inkjet printing.

[0078] Examples of active energy rays used to cure this composition include far-ultraviolet, ultraviolet, near-ultraviolet, and infrared rays, as well as electromagnetic waves such as X-rays and gamma rays, and electron beams, proton beams, and neutron beams. However, ultraviolet rays are preferred due to their curing speed, availability of irradiation equipment, and cost. When curing is performed using electron beams, curing can be achieved without using a photopolymerization initiator (C).

[0079] When curing with ultraviolet light, use a high-pressure mercury lamp, ultra-high-pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, chemical lamp, electrodeless discharge lamp, LED, etc., that emit light in the 150-450 nm wavelength range, at a pressure of 30-3,000 mJ / cm². 2 A certain amount of ultraviolet light should be applied. After UV irradiation, heating can be performed as needed to ensure complete curing.

[0080] The thickness of the adhesive layer after curing is typically 1 to 50 μm, preferably 2 to 20 μm, and more preferably 3 to 10 μm.

[0081] The adhesive strength of the adhesive layer between polymethyl methacrylate and polymethyl methacrylate is typically 5 N / 25 mm or more, preferably 10 N / 25 mm or more, and more preferably 15 N / 25 mm or more. The upper limit of the adhesive strength is typically 30 N / 25 mm or less.

[0082] The adhesive strength of the adhesive layer to the stainless steel and polymethyl methacrylate is typically 2.0 N / 25 mm or more, preferably 3.0 N / 25 mm or more, and more preferably 5.0 N / 25 mm or more. The upper limit of the adhesive strength is typically 50 N / 25 mm or less.

[0083] The adhesive strength of the adhesive layer between the polyimide resin and polymethyl methacrylate is typically 5 N / 25 mm or more, preferably 10 N / 25 mm or more, and more preferably 7 N / 25 mm or more. The upper limit of the adhesive strength is typically 80 N / 25 mm or less.

[0084] The adhesive strength of the adhesive layer can be measured according to the measurement method of the embodiment described later.

[0085] The storage modulus of the adhesive layer is typically 10 × 10 8 Pa or less, preferably 5 × 10 8 Pa or less, more preferably 10 × 10 7 It is less than or equal to Pa. Also, the lower limit of the storage modulus is usually 10 × 10 5It is Pa or higher.

[0086] The storage modulus of the adhesive layer can be measured according to the measurement method of the examples described later.

[0087] This composition is useful as an adhesive for bonding to various substrates, and specifically as an adhesive for plastic films. [Examples]

[0088] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In the examples, "parts" and "%" refer to mass.

[0089] Prior to the examples, the following components were prepared.

[0090] [Unsaturated compound (A)] A-1: Phenoxydiethylene glycol acrylate A'-1: Acryloylmorpholine A'-2: 2,2-Ethoxyethyl acrylate

[0091] [Urethane (meth)acrylate compound (B)] [Urethane (meth)acrylate compound (B-1)] In a four-necked flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 324.5 g (1.67 mol) of 1,3-bis(isocyanatomethyl)cyclohexane (b1), 126.0 g (1.11 mol) of neopentyl glycol (b2-2) (molecular weight: 104), 492.1 g (0.45 mol) of bifunctional polyester polyol (b2-1) [hydroxyl value 63 mg KOH / g, number average molecular weight calculated from hydroxyl value 1,781], 0.12 g of dibutylhydroxytoluene as a polymerization inhibitor, and 0.03 g of dibutyltin dilaurate as a reaction catalyst were charged, and the mixture was reacted at 60°C for 2 hours. Next, 51.7 g (0.45 mol) of 2-hydroxyethyl acrylate (b3) and 15.6 g (0.12 mol) of 2-hydroxypropyl acrylate (b3) were added to this system, and the reaction was carried out at 60°C for 3 hours. The reaction was terminated when the remaining isocyanate group was 0.3%, thereby obtaining a urethane acrylate compound (B-1) having a polyester structure [weight-average molecular weight 10,000].

[0092] [Urethane (meth)acrylate compound (B'-1)] In a four-necked flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 167.9 g (0.76 mol) of isophorone diisocyanate (b1), 742.2 g (0.38 mol) of a bifunctional polyether polyol (b2-2) [hydroxyl value 56 mg KOH / g, number average molecular weight calculated from hydroxyl value 2,000], 0.12 g of dibutylhydroxytoluene as a polymerization inhibitor, and 0.03 g of dibutyltin dilaurate as a reaction catalyst were charged, and the mixture was reacted at 60°C for 2 hours. Next, 89.9 g (0.77 mol) of 2-hydroxyethyl acrylate (b3) was charged into this system, and the mixture was reacted at 60°C for 3 hours. The reaction was terminated when the remaining isocyanate group was 0.3%, thereby obtaining a urethane acrylate compound (B'-1) having a polyether structure [weight average molecular weight 13,000].

[0093] [Urethane (meth)acrylate compound (B'-2)] In a flask equipped with an internal thermometer, stirrer, and condenser, 301 g (1.35 mol) of isophorone diisocyanate (b1), 540 g (0.68 mol) of polycarbonate diol (b2-2) [hydroxyl value 140.5 mg KOH / g, number average molecular weight calculated from hydroxyl value 799], and 0.1 g of dibutyltin dilaurate as a reaction catalyst were charged, and the mixture was reacted at 60°C for 2 hours. To this system, 159 g (1.37 mol) of 2-hydroxyethyl acrylate and 0.4 g of methoxyphenol as a polymerization inhibitor were further charged, and the mixture was reacted at 60°C until the residual isocyanate group was 0.3% or less, at which point the reaction was terminated to obtain a urethane (meth)acrylate compound (B'-2) having a carbonate structure [weight average molecular weight 5,000].

[0094] <Example 1> 65 parts of phenoxydiethylene glycol acrylate (A1) as an unsaturated compound (A), 35 parts of urethane (meth)acrylate compound (B-1) as a urethane (meth)acrylate compound (B), and 4 parts of 1-hydroxycyclohexyl-phenyl-ketone (Omnirad184, manufactured by IGM Resins BV) as a photocuring initiator (C) were mixed and dissolved at room temperature to obtain a composition (viscosity 3,000 mPa·s / 25℃).

[0095] <Examples 2-4, Comparative Examples 1-5> A composition was obtained in the same manner as in Example 1, except that the unsaturated compound (A) and the urethane (meth)acrylate compound (B) had the compositions shown in Table 1 below.

[0096] The compositions obtained in Examples 1-4 and Comparative Examples 1-5 above The following evaluations were conducted. The results are shown in Table 1.

[0097] [Coating properties] The coating properties of the composition were evaluated based on its viscosity according to the following evaluation criteria. (Evaluation Criteria) ○···100~10,000 mPa·s △···50 mPa·s or more and less than 100 mPa·s, or more than 10,000 mPa·s and 20,000 mPa·s or less ×···less than 50 mPa·s or more than 20,000 mPa·s

[0098] [Adhesive Strength] [Preparation of Evaluation Sample] The obtained composition was applied onto an easily adhesive polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., "Cosmo Shine A4360", thickness: 125 µm) using a bar coater to a thickness of 5 µm, thereby forming a composition layer. At this time, an uncoated surface of the composition was provided at an end portion of each film so that the film could be peeled off in the adhesion test. Thereafter, as an adherend, an easily adhesive polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., "Cosmo Shine A4300") or a polyimide resin film (thickness: 125 µm) was bonded to the obtained composition layer with a roller. Then, the composition layer was irradiated from the film side with a high-pressure mercury lamp so that the cumulative light amount was 1000 mJ / cm 2 , thereby curing the composition to form an adhesive layer, and a sample of film / adhesive layer / adherend was prepared.

[0099] [Measurement of Adhesive Strength] The end of the film that was not adhered to the PET film of the sample prepared above was fixed with a chuck, and the adhesiveness was evaluated by a 90° peel test using Shimadzu Autograph AG-X (manufactured by Shimadzu Corporation). The width of the sample in the test was 25 mm, and the measurement was performed at a peel rate of 300 mm / min.

[0100] [Storage Modulus] [Preparation of Evaluation Sample Piece] The composition was applied onto a heavy-release PET film using an applicator to a film thickness of 100 µm, and was subjected to two passes of ultraviolet irradiation from a height of 18 cm at a conveyor speed of 5.1 m / min using one high-pressure mercury lamp (cumulative irradiation dose: 800 mJ / cm 2An adhesive layer was formed on a highly peelable PET film. Next, this adhesive layer was punched out with a dumbbell to create strip-shaped samples measuring 5 mm in width and 30 mm in length. These strips were then peeled off the adhesive layer from the highly peelable PET film to obtain evaluation samples.

[0101] [Measurement of Storage Modulus] Using a dynamic viscoelasticity analyzer (UBM Corporation, "E-4000"), evaluation samples that had been pre-conditioned for more than 2 hours at a temperature of 23°C and a humidity of 50% Rh were measured for E'' (loss modulus) and E' (storage modulus) under the following measurement conditions, and tanδ (loss coefficient) was determined. (Measurement conditions) • Equipment: UBM E-4000 • Sample: 5mm, 30mm in length (20mm gap) • Measurement conditions: Tensile mode ·Measurement temperature: -150~150℃ • Heating conditions: 3°C / min • Frequency: 10Hz

[0102] [Table 1]

[0103] As shown in Table 1, the compositions of Examples 1 to 4 exhibited excellent adhesion to various films, and the resulting adhesive layer had a low storage modulus, making it flexible and able to follow expansion and contraction. Furthermore, the compositions of Examples 1 to 4 also exhibited excellent coating properties. On the other hand, the composition of Comparative Example 1, which had too high a mass content of the unsaturated compound (A), exhibited inferior adhesive strength to various films. Furthermore, the compositions of Comparative Examples 3 and 4, which did not contain the unsaturated compound (A), exhibited inferior adhesive strength to various films. Furthermore, the compositions of Comparative Examples 2 and 5, which used urethane (meth)acrylate compounds that did not have a polyester structure, exhibited inferior adhesive strength to various films. [Industrial applicability]

[0104] This composition is useful as an adhesive because it exhibits excellent adhesion to various substrates, preferably plastic films, after curing by irradiation with active energy rays. Furthermore, because this composition has excellent impact resistance after curing and also excellent coating properties, it can be used very suitably for bonding liquid crystal displays and protective films.

Claims

1. A composition comprising a monofunctional ethylenically unsaturated compound having an aryl group (A) and a urethane (meth)acrylate compound (B), The urethane (meth)acrylate compound (B) has a polyester structure and a weight-average molecular weight of 1,000 to 50,000. A composition in which the mass content ratio of the monofunctional ethylenically unsaturated compound (A) having an aryl group and the urethane (meth)acrylate compound (B) is (A):(B) = 80:20 to 20:

80.

2. Furthermore, the composition according to claim 1, further containing a photopolymerization initiator (C).

3. The composition according to claim 1 or 2, wherein the urethane (meth)acrylate compound (B) is a reaction product of a polyvalent isocyanate compound (b1), a polyester polyol (b2-1), and a hydroxyl group-containing (meth)acrylate compound (b3).

4. The composition according to claim 3, wherein the polyester polyol (b2-1) is a polyester-based polyol having a number average molecular weight of 60 to 20,000.

5. The composition according to claim 3, wherein the hydroxyl group-containing (meth)acrylate compound (b3) is a hydroxyl group-containing (meth)acrylate compound having one ethylenically unsaturated group.

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