Polarizing plate and adhesive composition for polarizing plate

Abstract

The present invention provides an adhesive composition for polarizing plates that can reduce hardening shrinkage force, and a polarizing plate using the adhesive composition. The polarizing plate of the present invention comprises, in sequence, a polarizing film, an adhesive layer, and a protective film. The adhesive layer is a cured layer of the adhesive composition. The adhesive composition includes a curing component and a photocationic polymerization initiator (D). The curing component includes: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq to 155 g / eq, a second aromatic epoxy compound (B) with an epoxy equivalent of greater than 155 g / eq and less than 1000 g / eq, and an oxobutane compound (C) having at least one oxobutane group within its molecule.

Description

Polarizing plate and adhesive composition for polarizing plate This invention relates to a polarizing plate and an adhesive composition for polarizing plates. Polarizing plates are used in display devices such as liquid crystal display devices and organic EL display devices. A polarizing plate has a structure in which a protective film such as a thermoplastic resin film is laminated on one or both sides of the polarizing film. The polarizing film and the protective film are usually bonded together using an adhesive, and curable adhesive compositions are known as such adhesives (e.g., Patent Documents 1, 2, etc.). [Previous Technical Documents] [Patent Literature] [Patent Document 1] Japanese Patent Application Publication No. 2011-236389 [Patent Document 2] Japanese Patent No. 5446902 It has been found that polarizing plates obtained by bonding polarizers and protective films using a curable adhesive composition sometimes warp. This warping of the polarizing plate may lead to reduced operability or, when applied to display devices, cause peeling of the polarizing plate. The inventors have discovered that if the curable adhesive composition shrinks significantly during curing, the curing shrinkage force of the curable adhesive composition increases, which may easily cause warping of the polarizing plate. The purpose of this invention is to provide an adhesive composition for polarizing plates that can reduce hardening shrinkage force and a polarizing plate using the adhesive composition. The present invention provides a polarizing plate and an adhesive composition for polarizing plates. [1] A polarizing plate comprising, in sequence, a polarizing film, an adhesive layer, and a protective film, The aforementioned adhesive layer is a hardened layer of the adhesive composition. The aforementioned adhesive composition system includes a curing component and a photocationic polymerization initiator (D). The aforementioned curing components include: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq or more but less than 155 g / eq, a second aromatic epoxy compound (B) with an epoxy equivalent of more than 155 g / eq but less than 1000 g / eq, and an oxobutane compound (C) having at least one oxobutane group in its molecule. [2] The polarizing plate as described in [1], wherein, in the aforementioned adhesive composition, In the total 100% by mass of the aforementioned curing components, the content of the aforementioned first aromatic epoxy compound (A) is 5.0% by mass or more and 40.0% by mass or less. In the total 100% by mass of the aforementioned curing components, the content of the aforementioned second aromatic epoxy compound (B) is 20.0% by mass or more and 60.0% by mass or less. In the total 100% by mass of the aforementioned curing components, the content of the aforementioned cyclobutane compound (C) is 5.0% by mass or more and 60.0% by mass or less. The content of the aforementioned photocationic polymerization initiator (D) is 0.5% to 10.0% by mass relative to 100% by mass of the total mass of the aforementioned curing components. [3] A polarizing plate as described in [1] or [2], wherein, The aforementioned second aromatic epoxy compound (B) is at least one of bisphenol A type epoxy compounds and bisphenol F type epoxy compounds. [4] The polarizing plate as described in any one of [1] to [3], wherein the aforementioned cyclobutane compound (C) is a monofunctional cyclobutane compound containing one intramolecular cyclobutane group. [5] A polarizing plate as described in any one of [1] to [4], wherein, The aforementioned oxobutane compound (C) contains 3-[(benzylmethyloxy)methyl]-3-ethyloxobutane. In the total 100% by mass of the aforementioned curing components, the content of the aforementioned 3-[(benzylmethyloxy)methyl]-3-ethyloxycyclobutane is 5.0% by mass or more and 40.0% by mass or less. [6] A polarizing plate as described in any one of [1] to [5], wherein the aforementioned curing component further comprises an alicyclic epoxy compound (E). [7] A polarizing plate as described in any one of [1] to [6], wherein the aforementioned polarizing plate is a polyvinyl alcohol resin film with dichroic pigments adsorbed and oriented. [8] A polarizing plate as described in any one of [1] to [7], wherein the aforementioned protective film is a (meth)acrylic resin film. [9] An adhesive composition for a polarizing plate, comprising a curing component and a photocationic polymerization initiator (D), wherein, The aforementioned curing components include: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq or more but less than 155 g / eq, a second aromatic epoxy compound (B) with an epoxy equivalent of more than 155 g / eq but less than 1000 g / eq, and an oxobutane compound (C) having at least one oxobutane group in its molecule. According to the present invention, an adhesive composition for a polarizing plate that can reduce hardening shrinkage force and a polarizing plate using the adhesive composition can be provided. 1,2:Polarizing plate 10: Polarizing film 11: First protective film (protective film) 15: First adhesive layer (adhesive layer) 21: Second protective film 25: Second adhesive layer Figure 1 is a schematic cross-sectional view of a polarizing plate illustrating one embodiment of the present invention. Figure 2 is a schematic cross-sectional view of a polarizing plate, representing another embodiment of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. (Polarizing plate) Figures 1 and 2 are schematic cross-sectional views illustrating one embodiment of the polarizing plate of the present invention. As shown in Figures 1 and 2, the polarizing plates 1 and 2 of this embodiment are sequentially laminated with a polarizer 10, a first adhesive layer 15, and a first protective film 11. The polarizer 10 and the first adhesive layer 15 are preferably in direct contact. The first adhesive layer 15 and the first protective film 11 are preferably in direct contact. The polarizing plate of this embodiment is the polarizing plate 2 shown in Figure 2. On the side opposite to the polarizer 10 and the first adhesive layer 15, the second adhesive layer 25 and the second protective film 21 can be sequentially deposited. The polarizer 10 and the second adhesive layer 25 are preferably in direct contact. The second adhesive layer 25 and the second protective film 21 are preferably in direct contact. Polarizing plates can be used in display devices. Examples of display devices include liquid crystal displays (LCDs) and organic EL displays. Display devices can be portable terminals such as smartphones or tablets, as well as televisions, digital photo frames, electronic signboards, measuring instruments or meters, office equipment, medical equipment, and computers. (First adhesive layer) The first adhesive layer 15 is a cured layer of the adhesive composition. The adhesive composition is a polarizing plate adhesive composition used to form the first adhesive layer 15 of the polarizer 10 and the first protective film 11, and includes a curing component and a photocationic polymerization initiator (D). The curing component includes: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq to 155 g / eq, a second aromatic epoxy compound (B) with an epoxy equivalent of greater than 155 g / eq and less than 1000 g / eq, and an oxobutane compound (C) having at least one oxobutane group in its molecule. The polarizing plate can be obtained by depositing the polarizer 10 and the first protective film 11 with the aforementioned adhesive composition in between, and then curing the adhesive composition to form a first adhesive layer 15. By using the adhesive composition described above to form the first adhesive layer 15, the shrinkage of the adhesive composition during curing can be suppressed, and the curing shrinkage force, which is a shrinkage force generated during the curing of the adhesive composition, can be reduced. Therefore, it is believed that by using the aforementioned adhesive composition to obtain polarizing plates 1 and 2, warping of polarizing plates 1 and 2 can be suppressed. The storage modulus of the first adhesive layer 15 at a temperature of 70°C can be 70 MPa or more, 90 MPa or more, 150 MPa or more, or 500 MPa or less, 400 MPa or less, or 300 MPa or less. Since the storage modulus of the first adhesive layer 15 is within the above range, cracking of the polarizers 1 and 2 can be suppressed even when they are exposed to alternating high and low temperature conditions. The storage modulus can be measured by the method described in the following embodiments. The first adhesive layer 15 has a moisture permeability of 60 g / (m²) at a temperature of 40°C and a relative humidity of 90%RH. 2 • 24hr) or less, and can be 1g / (m 2 • 24hr) or more, or 10g / (m 2 • 24hr) or more. In particular, when the polarizer 10 is a polyvinyl alcohol-based resin film with dichroic pigment adsorption orientation (described later), since the aforementioned moisture permeability of the first adhesive layer 15 is within the aforementioned range, warping of the polarizers 1 and 2 when exposed to a humid and hot environment can be suppressed. The aforementioned moisture permeability is for a (meth)acrylic resin film with a thickness of 60 μm (the aforementioned moisture permeability at the aforementioned temperature and relative humidity is 65 g / (m²)). 2 The value of the first adhesive layer 15 formed and measured over 24 hours can be determined by the method described in the examples below. The thickness of the first adhesive layer 15 may be, for example, less than 20 μm, less than 15 μm, less than 10 μm, or more than 0.5 μm, more than 1 μm, or more than 3 μm. The curing components contained in the above-mentioned adhesive composition may include other curing components besides those mentioned above. Other curing components may include, for example, alicyclic epoxy compounds (E) and aliphatic epoxy compounds. The adhesive composition described above may include components other than curing agents and photocationic polymerization initiators (D). Other components may include: photosensitizers, photosensitizing aids, polymerization accelerators, ion scavengers, antioxidants, light stabilizers, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, antistatic agents, leveling agents, pigments, and organic solvents. The aforementioned adhesive composition is preferably an active energy line curing adhesive composition that is cured by irradiation with active energy lines such as ultraviolet light, visible light, X-rays, or electron beams, causing the curing components to polymerize and harden. More preferably, the aforementioned adhesive composition is an ultraviolet curing adhesive composition that is cured by ultraviolet irradiation. When the above-mentioned adhesive composition is of the UV-curing type, the cumulative amount of light irradiation intensity can be, for example, 10 mJ / cm. 2 The above can also be 100 mJ / cm 2 The above, again, can be 1000mJ / cm 2 The following values ​​can also be 800 mJ / cm. 2 The ultraviolet light irradiating the above adhesive composition may be UVA (wavelength 320 to 400 nm) or UVB (wavelength 280 to 320 nm). When the above-mentioned adhesive composition is of the electron beam curing type, the electron beam irradiation line intensity can be, for example, 5 kGy or more, 10 kGy or more, 100 kGy or less, or 75 kGy or less. (First Aromatic Epoxide (A)) The curing component of the adhesive composition includes a first aromatic epoxy compound (A). The first aromatic epoxy compound (A) is an aromatic epoxy compound with an epoxy group equivalent of 100 g / eq to 155 g / eq. The aromatic epoxy compound comprises a compound having at least one epoxy group and at least one aromatic ring within its molecule. Preferably, the first aromatic epoxy compound (A) has one or two epoxy groups within its molecule. Preferably, the first aromatic epoxy compound (A) has one aromatic ring within its molecule. Because the adhesive composition includes the first aromatic epoxy compound (A), the moisture permeability of the first adhesive layer 15 can be reduced. Because the adhesive composition includes both a second aromatic epoxy compound (B) and a first aromatic epoxy compound (A), the adhesion strength of the first adhesive layer 15 is easily ensured, and the shrinkage of the adhesive composition during curing is easily suppressed. The epoxy group equivalent of the first aromatic epoxy compound (A) can be greater than 100 g / eq, greater than 110 g / eq, greater than 115 g / eq, or greater than 120 g / eq, or less than 153 g / eq, less than 145 g / eq, or less than 135 g / eq. The epoxy group equivalent of the first aromatic epoxy compound (A) is defined by the molecular weight of the first aromatic epoxy compound (A) per epoxy group, and can be determined according to the method specified in JIS K7236. Examples of the first aromatic epoxy compound (A) system include: glycidyl phenyl ether, resorcinol diglycidyl ether, and naphthalene-type epoxy compounds. Naphthalene-type epoxy compounds are polyglycidyl ethers of naphthalene or naphthalene derivatives. One or more of the first aromatic epoxy compounds (A) system may be used. The content of the first aromatic epoxy compound (A) in the adhesive composition is preferably 5.0% by mass or more, may be 10.0% by mass or more, or may be 15.0% by mass or more, and preferably 40.0% by mass or less, may be 35.0% by mass or less, may be 30.0% by mass or less, or may be 25.0% by mass or less, out of a total of 100% by mass of the curing components. When the adhesive composition contains two or more first aromatic epoxy compounds (A), the content of the first aromatic epoxy compound (A) is the total amount of the first aromatic epoxy compounds (A) contained in the adhesive composition. (Second Aromatic Epoxide (B)) The curing component of the adhesive composition includes a second aromatic epoxy compound (B). The second aromatic epoxy compound (B) is an aromatic epoxy compound with an epoxy group equivalent greater than 155 g / eq and less than 1000 g / eq. As described above, the aromatic epoxy compound is a compound containing at least one epoxy group and at least one aromatic ring within its molecule. Preferably, the second aromatic epoxy compound (B) has two epoxy groups within its molecule. Preferably, the second aromatic epoxy compound (B) has two or more aromatic rings within its molecule. Because the adhesive composition includes the second aromatic epoxy compound (B), the moisture permeability of the first adhesive layer 15 can be reduced. Since the second aromatic epoxy compound (B) is used together with the aforementioned first aromatic epoxy compound (A), the adhesion strength of the first adhesive layer 15 is easily ensured, and the shrinkage of the adhesive composition during curing is easily suppressed. The epoxy group equivalent of the second aromatic epoxy compound (B) can be 170 g / eq or more, 180 g / eq or more, or 200 g / eq or more, or 900 g / eq or less, 700 g / eq or less, 500 g / eq or less, or 300 g / eq or less. The epoxy group equivalent of the second aromatic epoxy compound (B) is defined by the molecular weight of the second aromatic epoxy compound (B) per epoxy group, and can be determined according to the method specified in JIS K7236. Examples of the second aromatic epoxy compound (B) include: bisphenol-type epoxy compounds that are epoxypropyl ethers of bisphenol derivatives such as bisphenol A, bisphenol F, bisphenol S, bisphenol M, and bisphenol P; and epoxypropyl ethers that are epoxypropyl ethers of bisphenol or its derivatives. The second aromatic epoxy compound (B) is preferably a bisphenol-type epoxy compound, and more preferably at least one of bisphenol A-type epoxy compounds and bisphenol F-type epoxy compounds. The second aromatic epoxy compound (B) may be an epoxy-based resin. One or more types of the second aromatic epoxy compound (B) may be used. The content of the second aromatic epoxy compound (B) in the adhesive composition is preferably 20.0% by mass or more, may be 25.0% by mass or more, or may be 30.0% by mass or more, and preferably 60% by mass or less, may be 50.0% by mass or less, or may be 45.0% by mass or less, out of a total of 100% by mass of the curing components. When the adhesive composition contains two or more second aromatic epoxy compounds (B), the content of the second aromatic epoxy compound (B) is the total amount of the second aromatic epoxy compounds (B) contained in the adhesive composition. The mixing ratio of the first aromatic epoxy compound (A) and the second aromatic epoxy compound (B) in the adhesive composition (first aromatic epoxy compound (A) / second aromatic epoxy compound (B)) is preferably 0.1 or more, more preferably 0.3 or more, more preferably 0.4 or more, preferably 1.4 or less, more preferably 1.2 or less, more preferably 1.0 or less, and especially preferably 0.8 or less. Since the mixing ratio of the first aromatic epoxy compound (A) and the second aromatic epoxy compound (B) is within the above range, the adhesion strength of the first adhesive layer 15 is easily ensured, and the changes in the optical properties of the polarizing plates 1 and 2 during durability tests under high temperature and high humidity conditions (e.g., a humid and hot environment with a temperature of 80°C and a relative humidity of 90%) are easily suppressed. The combined amount of the first aromatic epoxy compound (A) and the second aromatic epoxy compound (B) in the adhesive composition, within 100% by mass of the combined amount of the curing components, is preferably 40.0% by mass or more, may be 45.0% by mass or more, may be 50.0% by mass or more, preferably 90.0% by mass or less, may be 80.0% by mass or less, and may be 70.0% by mass or less. Since the combined amount of the first aromatic epoxy compound (A) and the second aromatic epoxy compound (B) is included within the above range, the adhesion strength of the first adhesive layer 15 is easily ensured, and the shrinkage of the adhesive composition during curing is easily suppressed. (Oxycyclobutane compound (C)) The curing component of the adhesive composition includes an oxobutane compound (C). The oxobutane compound (C) is a compound having at least one oxobutane ring (oxobutane ring) within its molecule, and can be any of aliphatic compounds such as chain aliphatic compounds and alicyclic compounds, or aromatic compounds. In this specification, the oxobutane compound (C) refers to a compound that does not have an epoxy group within its molecule. Because the adhesive composition includes an oxobutane compound (C), the curing speed and viscosity of the adhesive composition can be adjusted, and its reactivity can be improved. The cyclobutane compound (C) preferably has one or two intramolecular cyclobutyl groups. The cyclobutane compound (C) is preferably a monofunctional cyclobutane compound with one intramolecular cyclobutyl group, and can be a mixture of monofunctional cyclobutane compounds and polyfunctional cyclobutane compounds with two or more intramolecular cyclobutyl groups. The monofunctional cyclobutane compound is preferably a monofunctional cyclobutane compound containing an aromatic ring. The polyfunctional cyclobutane compound is preferably an aliphatic compound with two intramolecular cyclobutyl groups. One or more types of cyclobutane compounds (C) can be used. Examples of monofunctional cyclobutane compounds include: 3-ethyl-3-(phenoxy)methylcyclobutane, 3-[(phenylmethyloxy)methyl]-3-ethylcyclobutane, 3-ethyl-3-(cyclohexyloxymethyl)cyclobutane, 3-ethyl-3-(2-ethylhexyloxymethyl)cyclobutane, 3-ethyl-3-hydroxymethylcyclobutane, and 3-ethyl-3-(chloromethyl)cyclobutane. One or more monofunctional cyclobutane compounds may be used. Examples of multifunctional oxocyclobutane compounds include: 3,7-bis(3-oxocyclobutyl)-5-oxa-nonane, 1,4-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]propane, and ethylene glycol bis(3-ethyl-3-oxocyclobutylmethyl] Ethers, triethylene glycol bis(3-ethyl-3-oxocyclobutylmethyl) ether, tetraethylene glycol bis(3-ethyl-3-oxocyclobutylmethyl) ether, 1,4-bis(3-ethyl-3-oxocyclobutylmethoxy)butane, 1,6-bis(3-ethyl-3-oxocyclobutylmethoxy)hexane, 3-ethyl-3{[(3-ethyloxocyclobutane-3-yl)methoxy]methyl}oxocyclobutane, phenylenedimethyldioxocyclobutane, etc. One or more polyfunctional oxocyclobutane compounds may be used. The cyclobutane compound (C) preferably comprises any one of 3-[(benzylmethyloxy)methyl]-3-ethylcyclobutane, 3-ethyl-3-(phenoxy)methylcyclobutane, and 3-ethyl-3{[(3-ethylcyclobutane-3-yl)methoxy]methyl}cyclobutane, more preferably comprises at least one of 3-[(benzylmethyloxy)methyl]-3-ethylcyclobutane and 3-ethyl-3{[(3-ethylcyclobutane-3-yl)methoxy]methyl}cyclobutane, and even more preferably comprises 3-[(benzylmethyloxy)methyl]-3-ethylcyclobutane. The content of the cyclobutane compound (C) in the adhesive composition is preferably 5.0% by mass or more, and may be 10.0% by mass or more, 15.0% by mass or more, 20.0% by mass or more, or 25.0% by mass or more, and preferably 60.0% by mass or less, and may be 55.0% by mass or less, 50.0% by mass or less, 45.0% by mass or less, or 40.0% by mass or less. When the adhesive composition contains two or more cyclobutane compounds (C), the content of the cyclobutane compound (C) is the total amount of the cyclobutane compounds (C) contained in the adhesive composition. When the cyclobutane compound (C) contains a monofunctional cyclobutane compound, the content of the monofunctional cyclobutane compound, within 100% by mass of the total amount of curing components, may be 5.0% by mass or more, 10.0% by mass or more, or 15.0% by mass or more, and may be 40.0% by mass or less, 35.0% by mass or less, or 30.0% by mass or less. When the adhesive composition contains two or more monofunctional cyclobutane compounds, the content of the monofunctional cyclobutane compound is the total amount of the monofunctional cyclobutane compounds contained in the adhesive composition. When 3-[(benzylmethyloxy)methyl]-3-ethyloxycyclobutane is included as an oxycyclobutane compound (C), the content of 3-[(benzylmethyloxy)methyl]-3-ethyloxycyclobutane in 100% by mass of the total amount of the curing components is preferably 5.0% by mass or more, may be 10.0% by mass or more, may be 15.0% by mass or more, and preferably 40.0% by mass or less, may be 35.0% by mass or more, may be 30.0% by mass or less. (Alicyclic epoxides (E)) The adhesive composition may include an alicyclic epoxy compound (E) as a curing component other than the aforementioned curing component. The alicyclic epoxy compound (E) is a compound having an alicyclic epoxy group. In this specification, an alicyclic epoxy group refers to an epoxy group bonded to an alicyclic ring, and has an oxygen atom -O- in the structure shown below. In the following formulas, m is an integer from 2 to 5. The alicyclic epoxy compound (E) is formed by removing (CH) from the following formula. 2) m Compounds in which one or more hydrogen atoms are bonded to other chemical structures. (CH) 2) m One or more hydrogen atoms can be substituted by straight-chain alkyl groups such as methyl and ethyl. Alicyclic epoxy compounds (E) may have one or more alicyclic epoxy groups, but two are preferred. Examples of alicyclic epoxy (E) compounds include: 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, 1,2-epoxy-4-vinylcyclohexane, 1,2-epoxy-1-methyl-4-(1-methylepoxyethyl)cyclohexane, methyl 3,4-epoxycyclohexyl methacrylate, 4-(1,2-epoxyethyl)-1,2-epoxycyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, ethylbis(3,4-epoxycyclohexane carboxylate), oxydiethylbis(3,4-epoxycyclohexane carboxylate), 1,4-cyclohexanedimethylbis(3,4-epoxycyclohexane ester), 3-(3,4-epoxycyclohexylmethoxycarbonyl)propyl 3,4-epoxycyclohexane carboxylate, etc. One or more alicyclic epoxy (E) compounds can be used. Relative to the total mass percentage of the curing components, the content of alicyclic epoxy compounds (E) in the adhesive composition may be 1.0% by mass or more, 5.0% by mass or more, or 10.0% by mass or more, or 50.0% by mass or less, 40.0% by mass or less, or 30.0% by mass or less. When the adhesive composition contains two or more alicyclic epoxy compounds (E), the content of alicyclic epoxy compounds (E) is the total mass percentage of alicyclic epoxy compounds (E) contained in the adhesive composition. (Aliphatic epoxy compounds) The adhesive composition may contain curing components other than aliphatic epoxy compounds as curing agents. In this specification, aliphatic epoxy compounds are compounds that do not possess aromatic rings or alicyclic epoxy groups. Aliphatic epoxy compounds may possess one or more epoxy groups, but more than two are preferred. Examples of aliphatic epoxy compounds include polyoxypropyl ethers of aliphatic polyols or their alkyl oxide adducts. More specifically, examples include: diglycidyl ether of 1,4-butanediol; diglycidyl ether of 1,6-hexanediol; triglycidyl ether of glycerol; triglycidyl ether of trimethylolpropane; diglycidyl ether of polyethylene glycol; diglycidyl ether of propylene glycol; and polyoxypropyl ethers of polyether polyols obtained by adding one or more alkyl oxides (ethylene oxide or propylene oxide) to aliphatic polyols such as ethylene glycol, propylene glycol, or glycerol. One or more aliphatic epoxy compounds may be used. There is no particular limitation on the content of aliphatic epoxy compounds in the adhesive composition. However, relative to 100% by mass of the total amount of curing components, it can be set as 1% or more by mass, 5% or more by mass, or 10% or more by mass, or, for example, 50% or less by mass, 40% or less by mass, or 30% or less by mass. When the adhesive composition contains two or more aliphatic epoxy compounds, the content of aliphatic epoxy compounds is the total amount of aliphatic epoxy compounds contained in the adhesive composition. (Photocationic polymerization initiator (D)) The adhesive composition includes a photocationic polymerization initiator (D). This allows the curing components within the adhesive composition to undergo cationic polymerization to form a cured layer. The photocationic polymerization initiator (D) generates cationic species or Lewis acids by irradiation with an active energy beam, initiating the polymerization reaction of the curing components. Because the photocationic polymerization initiator (D) uses photocatalysis, it maintains excellent stability and workability even when mixed with curing components. Examples of photocationic polymerization initiators (D) include: aromatic diazonium salts; aromatic monazite salts and aromatic strontium salts; iron-aromatic hydrocarbon complexes, etc. Examples of aromatic diazonium salts include the following compounds. Benzenediazohexafluoroantimonate, Benzenediazohexafluorophosphate, Benzenediazohexafluoroborate, etc. Examples of aromatic uranium salts include the following compounds. Diphenylbenzyl borate, Diphenyl monazine hexafluorophosphate, Diphenylmonafluoroantimonate, Di(4-nonylphenyl)hexafluorophosphate, etc. Examples of aromatic strontium salts include the following compounds. Triphenylsulphur hexafluorophosphate, Triphenylsilane hexafluoroantimonate, Triphenylsperylene(pentafluorophenyl)borate, 4,4'-Bis(diphenylstrontium)diphenyl sulfide dihexafluorophosphate, 4,4'-Bis[di(β-hydroxyethoxy)phenylsmuryl]diphenyl sulfide dihexafluoroantimonate, 4,4'-Bis[di(β-hydroxyethoxy)phenylspermyl]diphenyl sulfide dihexafluorophosphate, 7-[bis(p-tolyl)smurfyl]-2-isopropylthioxanthone hexafluoroantimonate, 7-[bis(p-tolyl)smurnyl]-2-isopropylthioxanthone tetra(pentafluorophenyl)borate, 4-Phenylacetyl-4'-diphenylsulpho-diphenylsulfide hexafluorophosphate, 4-(p-tert-butylphenylcarbonyl)-4'-diphenylsulphyl-diphenyl sulfide hexafluoroantimonate, 4-(p-tert-butylphenylcarbonyl)-4'-bis(p-tolyl)sulpho-diphenyl sulfide tetra(pentafluorophenyl)borate, etc. Examples of iron-aromatic hydrocarbon complexes include the following compounds. Xylene-cyclopentadienyl iron(II) hexafluoroantimonate Cumene-cyclopentadienyl iron(II) hexafluorophosphate Xylene-cyclopentadienyl iron(II) benzo[trifluoromethylsulfonyl]methane, etc. One or more photocationic polymerization initiators (D) may be used. Among the above, aromatic strontium salts, in particular, also have ultraviolet absorption characteristics in the wavelength region around 300 nm, so it is preferable to use them to obtain a first adhesive layer 15 with excellent curing properties and good mechanical strength or adhesion strength. Relative to the total mass of the curing components, the content (solid content) of the photocationic polymerization initiator (D) in the adhesive composition is preferably 0.5% by mass or more, may be 1.0% by mass or more, or may be 3.0% by mass or more, and preferably 10.0% by mass or less, may be 8.0% by mass or less, or may be 5.0% by mass or less. When the adhesive composition contains two or more photocationic polymerization initiators (D), the content of the photocationic polymerization initiator (D) is the total mass of the photocationic polymerization initiators (D) contained in the adhesive composition. (Second adhesive layer) The second adhesive layer 25 may be a hardened layer formed using the adhesive composition used to form the first adhesive layer 15, or it may be a hardened layer of an adhesive composition other than that adhesive composition. When the second adhesive layer 25 is a hardened layer of the aforementioned adhesive composition, the first adhesive layer 15 and the second adhesive layer 25 may be hardened layers of adhesive compositions with the same composition, or they may be hardened layers of adhesive compositions with different compositions. Other adhesive composition systems include, for example, known aqueous adhesives, and known active energy line curing adhesives other than those mentioned above. Examples of water-based adhesives include adhesives that dissolve or disperse polyvinyl alcohol resin or ethyl amino formaldehyde resin in water. Active energy line curing adhesives are adhesives that cure under the influence of active energy lines such as ultraviolet light, visible light, X-rays, or electron beams. Regarding the curing components, examples of active energy line curing adhesives include: epoxy compounds that cure via cationic polymerization and photocationic polymerization initiators; and (meth)acrylic acid compounds and photofree radical polymerization initiators that are free radical polymerizable. In this specification, "(meth)acrylic acid" refers to at least one of acrylic acid and methacrylic acid. The same applies to "(meth)acrylic acid" and the like. Examples of epoxy compounds and photocationic polymerization initiators include those listed above. Examples of (meth)acrylic acid compounds include: (meth)acrylate monomers having one or more (meth)acrylic acid groups in their molecules; (meth)acrylate oligomers obtained by reacting two or more functional compounds and having at least two (meth)acrylic acid groups in their molecules; and other compounds containing (meth)acrylic acid groups. Examples of photoradical polymerization initiators include: acetobenzene initiators, benzophenone initiators, benzoin ether initiators, thioxanthraquinone initiators, xanthraquinones, fumonisins, camphorquinone, benzaldehyde, anthraquinones, etc. The thickness of the second adhesive layer 25 may be less than 20 μm, less than 15 μm, or less than 10 μm, or more than 0.5 μm, more than 1 μm, or more than 3 μm. (Polarizing film) A polarizer possesses the following property: when unpolarized light is incident, it allows linearly polarized light with a vibrational plane orthogonal to the absorption axis to pass through. The polarizer can be a polyvinyl alcohol-based resin film (hereinafter sometimes referred to as "PVA-based film") formed by adsorbing and oriented dichroic pigments, or it can be a film containing liquid crystals formed by coating a composition comprising compounds with anisotropic absorption and liquid crystal properties onto a substrate film. The compounds with anisotropic absorption and liquid crystal properties can be a mixture of anisotropic pigments and liquid crystal compounds, or they can be pigments with anisotropic absorption and liquid crystal properties. Preferably, the polarizer is a PVA-based resin film formed by adsorbing and oriented dichroic pigments. Examples of PVA-based polarizing films include: polyvinyl alcohol films, partially formaldehyde-modified polyvinyl alcohol films, and partially saponified ethylene / vinyl acetate copolymer films, which undergo dyeing and stretching treatments with dichroic dyes. If necessary, the PVA film, which has undergone dyeing treatment to orient the dichroic dye through adsorption, can be treated with a boric acid aqueous solution. Afterward, a washing step to remove the boric acid aqueous solution can be performed. Known methods can be used in each step. Polyvinyl alcohol (PVA) resins (hereinafter sometimes referred to as "PVA-based resins") can be manufactured by saponifying polyvinyl acetate (PVA) resins. Besides polyvinyl acetate homopolymers, PVA resins can also be copolymers of vinyl acetate with other monomers that can copolymerize with vinyl acetate. Examples of other monomers that can copolymerize with vinyl acetate include: unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides containing ammonium groups. The degree of saponification of PVA-based resins is typically around 85 to 100 moles, preferably above 98 moles. PVA-based resins can be modified; for example, aldehyde-modified polyvinyl formaldehyde or polyvinyl acetal can be used. The average degree of polymerization of PVA-based resins is typically around 1,000 to 10,000, preferably around 1,500 to 5,000. The degree of saponification and average degree of polymerization of PVA-based resins can be determined according to JIS K 6726 (1994). A lower average degree of polymerization (below 1000) makes it difficult to obtain good polarization performance, while a degree exceeding 10,000 results in poor film processability. Examples of dichroic pigments that can be oriented for adsorption on PVA membranes include iodine or dichroic dyes. Iodine is preferred as a dichroic pigment. Examples of dichroic dyes include: Red BR, Red LR, Red R, Pink LB, Magenta BL, Maroon GS, Sky Blue LG, Tartrazine, Blue BR, Blue 2R, Navy Blue RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Super Blue G, Super Blue GL, Super Orange GL, Direct Sky Blue, Direct Fast Orange S, Fast Black, etc. A method for manufacturing a PVA-based polarizer may include the following steps: preparing a substrate film, coating the substrate film with a resin solution such as a PVA-based resin, and drying it to remove the solvent, thereby forming a resin layer on the substrate film. Furthermore, a primer layer may be pre-formed on the surface of the substrate film where the resin layer is formed. The substrate film may be a film made of a resin material used to form the thermoplastic resin described later for the first and second protective films. Examples of materials used as the primer layer include cross-linked resins of the hydrophilic resin used in polarizers. Then, the amount of water and other solvents in the resin layer is adjusted as needed. Next, the substrate film and resin layer are uniaxially stretched. Then, the resin layer is dyed with a dichroic pigment to allow the pigment to adsorb and align on the resin layer. Next, the resin layer formed by the adsorption and alignment of the dichroic pigment is treated with a boric acid aqueous solution as needed. Then, a washing step to remove the boric acid aqueous solution is performed. In this way, a resin layer with adsorption and alignment of the dichroic pigment is manufactured, which is a PVA-based film for polarizing. Known methods can be used in each step. When the dichroic dye is iodine, the amount of boric acid in the boric acid-containing aqueous solution used to treat the iodine-oriented PVA membrane or resin layer is typically about 2 to 15 parts by mass per 100 parts by mass of water, preferably 5 to 12 parts by mass. This boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is typically about 0.1 to 15 parts by mass per 100 parts by mass of water, preferably about 5 to 12 parts by mass. The immersion time in the boric acid-containing aqueous solution is typically about 60 to 1,200 seconds, preferably about 150 to 600 seconds, more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is typically above 50°C, preferably 50 to 85°C, more preferably 60 to 80°C. The uniaxial stretching of the PVA-based film, substrate film, and resin layer can be performed before dyeing, during dyeing, during boric acid treatment after dyeing, or in multiple stages. The PVA-based film, substrate film, and resin layer can be uniaxially stretched in the MD direction (film transport direction). This can be done between rollers with different circumferential speeds, or using hot rollers. Alternatively, the PVA-based film, substrate film, and resin layer can be uniaxially stretched in the TD direction (perpendicular to the film transport direction). This can be done using a so-called tenter frame method. Furthermore, the above stretching can be dry stretching in the atmosphere or wet stretching in a state where the PVA-based film or resin layer is swollen with a solvent. To exhibit the performance of the polarizer, the elongation ratio is 4 times or more, preferably 5 times or more, and especially preferably 5.5 times or more. There is no particular upper limit to the elongation ratio, but from the viewpoint of suppressing cracking, it is preferably 8 times or less. A polarizer manufactured using a substrate film manufacturing method can be obtained by peeling off the substrate film after laminating a protective film. This method allows for further thinning of the polarizer. The thickness of polarizers belonging to the PVA film system is preferably 1μm or more, can be 2μm or more, can also be 5μm or more, and preferably 30μm or less, more preferably 15μm or less, can be 10μm or less, and can also be 8μm or less. Examples of film systems containing a liquid crystal polarizing layer include polarizers obtained by coating a composition containing a pigment with liquid crystal properties and anisotropic absorption, or a composition containing a pigment with anisotropic absorption and polymerizable liquid crystal, onto a substrate film. Examples of substrate film systems include films using resin materials described below, which are thermoplastic resins used to form the first and second protective films described later. Examples of film systems containing a liquid crystal polarizing layer include polarizing layers disclosed in Japanese Patent Application Publication No. 2013-33249, etc. The combined thickness of the substrate film and polarizer formed in the above manner is preferably smaller. However, if it is too small, there will be a tendency for the strength to decrease and the processability to deteriorate. It is usually below 20μm, preferably below 5μm, and even more preferably 0.5 to 3μm. (First protective film, second protective film) As the first and second protective films (hereinafter, sometimes both are referred to as "protective films"), films formed from thermoplastic resins with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and elongation can be used. Specific examples of thermoplastic resins include: cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether resins; polyether resins; polycarbonate resins; polyamide resins such as nylon or aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene / propylene copolymers; cyclic polyolefin resins having a cyclic system and a nobornene structure (also called nobornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; and mixtures thereof. The protective film can be a phase difference film with any phase difference value. The phase difference film can be obtained by stretching (uniaxial stretching or biaxial stretching, etc.) a film formed from the above-mentioned thermoplastic resin, or by forming a liquid crystal layer on the film. The protective film may possess anti-reflective, anti-glare, or hard coating properties. If the protective film does not possess these properties, an anti-reflective layer, anti-glare layer, or hard coating layer may be provided on one side of the polarizing plate. Preferably, the surface functional layer is positioned in direct contact with the protective film. Preferably, the surface functional layer is located on the side of the protective film opposite to the polarizing film side. The protective film is usually 5μm or larger, and can be 10μm or larger. It is also usually less than 200μm, and can be less than 150μm, less than 100μm, or less than 80μm. The first protective film and the second protective film can be of the same type or different types. From the viewpoint of adhesion to the first adhesive layer 15 obtained using the above-described adhesive composition, the first protective film is preferably a (meth)acrylic resin film using (meth)acrylic resins such as polymethyl methacrylate as the thermoplastic resin. When the second adhesive layer is a cured layer of the above-described adhesive composition, the second protective film is preferably also a (meth)acrylic resin film. [Example] The present invention will be described in more detail below with reference to embodiments and comparative examples, but the present invention is not limited to these examples. The materials used in the embodiments and comparative examples are as follows. (First Aromatic Epoxide (A)) Compound (A1): Resorcinol diglycidyl ether (trade name "EX-201" obtained from NAGASE CHEMTEX Co., Ltd., epoxy equivalent: 117 g / eq) Compound (A2): Phenyl glycidyl ether (trade name "EX-141" obtained from NAGASE CHEMTEX Co., Ltd., epoxy equivalent: 151 g / eq) (Second Aromatic Epoxide (B)) Compound (B1): Bisphenol A diglycidyl ether (trade name "EP-4100E" obtained from ADEKA Corporation, epoxy equivalent: 190 g / eq) Compound (B2): Bisphenol F diglycidyl ether (trade name "EXA-830CRP" obtained from DIC Corporation, epoxy equivalent: 156 to 168 g / eq) (Alicyclic epoxides (E)) Compound (E1): 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (trade name "CEL2021P" obtained from DAICL Chemical Industry Co., Ltd.) (Oxycyclobutane compound (C)) Compound (C1): 3-Ethyl-3{[(3-ethyloxocyclobutane-3-yl)methoxy]methyl}oxocyclobutane (trade name "OXT-221" obtained from Dong-A Synthetic Co., Ltd.) Compound (C2): 3-[(benzylmethyloxy)methyl]-3-ethyloxycyclobutane (trade name "TCM-104" obtained from Toronly Corporation) (Photocationic polymerization initiator (D)) Compound (D1): 50% propyl carbonate solution of a triaryl strontium salt photocationic polymerization initiator (trade name "CPI-100P" obtained from SAN-APRO Co., Ltd.) [Example 1] (Preparation of adhesive composition (x1)) The adhesive composition (x1) is prepared by mixing the curing components shown in Table 1 at the ratios shown in Table 1 (total 100 parts by mass), and by mixing the photocationic polymerization initiator (D) at the ratios shown in Table 1 (as a ratio of solid components). (Modulation of adhesive composition (y)) An adhesive composition (y) was prepared by mixing 70 parts by weight of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (trade name "CEL2021P" obtained from DAICL Chemical Industry Co., Ltd.), 20.0 parts by weight of neopentyl glycol diglycidyl ether (trade name "EX-211" obtained from NAGASE CHEMTEX Co., Ltd.), 10.0 parts by weight of 2-ethylhexyl glycidyl ether (trade name "EX-121" obtained from NAGASE CHEMTEX Co., Ltd.), and 5.5 parts by weight of a 50% solution of triaryl strontium salt photocationic polymerization initiator, propyl carbonate (trade name "CPI-100P" obtained from SAN-APRO Co., Ltd.). (Making of polarizing plates) A corona discharge treatment was applied to one side of the first protective film (a 60 μm thick polymethyl methacrylate (PMMA) film). On the corona-treated side, the prepared adhesive composition (x1) was applied using a rod coater. Then, using a roller, a polarizer (a polyvinyl alcohol-iodine polarizing film with a thickness of approximately 23 μm) was bonded to the coated side of the adhesive composition (x1) of the first protective film to obtain a polarizer with the first protective film attached. Next, a corona discharge treatment was applied to one side of the second protective film (a 50 μm thick phase retardation film made of cyclic polyolefin resin (norbornene resin) [trade name "ZEONOR" manufactured by ZEON Corporation of Japan]). On this corona-discharge treated side, the prepared adhesive composition (y) was applied using a rod coater. Then, using a roller, the polarizer side of the polarizer with the first protective film attached was bonded to the coated side of the second protective film on the adhesive composition (y) side to obtain a laminate. The total cumulative irradiation intensity (cumulative light intensity in the wavelength region of 320 to 400 nm) from the second protective film side of the laminate was approximately 200 mJ / cm². 2 (Measurement values ​​obtained using a measuring instrument: Fusion UV Corporation's "UV Power Puck II") Ultraviolet light (UVB). This allows the adhesive composition (x1) to polymerize and harden to form a first adhesive layer, and the adhesive composition (y) to polymerize and harden to form a second adhesive layer, thus obtaining a polarizing plate. The polarizing plate has a layer structure of a first protective film / first adhesive layer / polarizer / second adhesive layer / second protective film. The thickness of the first adhesive layer is approximately 5 μm, and the thickness of the second adhesive layer is approximately 3 μm. [Examples 2 to 6, Comparative Examples 1 and 2] Except for changing the amounts of the curing components and photocationic polymerization initiator (D) shown in Table 1 to those shown in Table 1, the adhesive compositions (X2) to (x8) were prepared in the same manner as in Example 1. The polarizing plate was obtained in the same manner as in Example 1, except that adhesive compositions (x2) to (x8) were used. The first adhesive layer and polarizing plate formed using the adhesive compositions (x1) to (x8) prepared in the Examples and Comparative Examples were evaluated as follows. The results are presented in Table 1. [Determination of the storage modulus of the first adhesive layer at 70°C] Adhesive compositions (x1) to (x8) were applied to one side of a 50 μm thick cyclic polyolefin resin film using a rod coater, and a further 50 μm thick cyclic polyolefin resin film was deposited on the coated surface. To avoid poor curing of the adhesive composition, the thickness of the adhesive layer was set to less than 20 μm. Next, the total cumulative light intensity (the cumulative intensity of light irradiation in the wavelength region of 320 to 400 nm) was approximately 200 mJ / cm². 2 (Measurement equipment: UV Power Puck II manufactured by Fusion UV Corporation) Ultraviolet (UVB) light was used to polymerize and harden the adhesive composition. This was cut into 5mm × 30mm pieces, and the cyclic polyolefin resin film was peeled off to obtain a test piece containing the hardened film of the adhesive composition. Using a dynamic viscoelasticity measuring device (DVA-220 manufactured by IT Measurement & Control Co., Ltd.) with its long side in the stretching direction, the test piece was held with the grippers spaced 2cm apart. The stretching and shrinkage frequency was set to 10Hz, and the heating rate was set to 10℃ / minute. The storage modulus (MPa) at 70℃ was determined. [Determination of hardening shrinkage force of adhesive compositions (x1) to (x8)] The curing shrinkage force of adhesive compositions (x1) to (x8) was measured using a rotary viscoelasticity measuring device (Anton Paar Co., Ltd., trade name "Physica MCR 301") equipped with a high-brightness mercury-xenon lamp (Hamamatsu Photonics Co., Ltd., trade name "Lightning Cure"). Specifically, it was measured using any one of the steps / adhesive compositions (x1) to (x8) / measuring system (8mm). With parallel plates configured, adhesive components (x1) to (x8) were mounted on the apparatus. The gap between the step and the measurement system was set to 50 μm. Next, adhesive components (x1) to (x8) that had seeped from the measurement system were scraped off. After stabilization in the Normal Force, measurements were started at a temperature of 25°C and a data acquisition interval of 0.5 sec / point. Ten seconds after the start of measurement, the total cumulative light intensity (the cumulative intensity of light irradiation in the wavelength region of 320 to 400 nm) was approximately 50 mJ / cm². 2 (Measurements were obtained using a UVB instrument manufactured by Fusion UV Corporation, "UV Power Puck II") Adhesive compositions (x1) to (x8) were cured under ultraviolet (UVB) light. During curing, the absolute value of the Normal Force generated by the measuring system was determined as the curing shrinkage force of adhesive compositions (x1) to (x8). The curing shrinkage force values ​​shown in Table 1 represent the absolute values ​​of the Normal Force 100 seconds after the start of the measurement. A smaller Normal Force value indicates a larger absolute value, and a greater shrinkage of the adhesive composition during curing. [Determination of the adhesion between the first protective film and the polarizer] Following the order described in the examples and comparative examples, a corona discharge treatment was applied to the surface of the second protective film of the polarizing plate. An acrylic adhesive sheet was then bonded to the corona-treated surface to form a polarizing plate with an adhesive layer. From the obtained polarizing plate with the adhesive layer, test pieces with a width of 25 mm and a length of approximately 200 mm were cut. The adhesive layer was then bonded to a soda glass substrate to obtain a test sample. The test sample was stored at a temperature of 23°C and a relative humidity of 55% for 24 hours. Then, the blade of a cutter was inserted between the first protective film and the polarizing film, and 30 mm was peeled off from the end in the length direction. The peeled portion was gripped by the gripping part of a universal tensile testing machine (product name "AGS-50NX" manufactured by Shimadzu Corporation). The test piece in this state was subjected to a 180-degree peel test at a temperature of 23°C and a relative humidity of 55%, according to JIS K 6854-2:1999 "Adhesives - Peel Bond Strength Test Method - Part 2: 180-degree Peel", with a gripping and moving speed of 300 mm / min. The average peel force covering a length of 60 mm excluding the gripping part was calculated, and this was used as the adhesion strength. ※1 in Table 1 indicates that the first protective film and the polarizer of the test sample cannot be cut, meaning that even if a cutting blade is inserted between them, the first protective film and the polarizer cannot be separated. [Measurement of moisture permeability of the first adhesive layer] A 60 μm thick PMMA film, after being corona-treated, was coated onto adhesive compositions (x1) to (x8) prepared in the examples and comparative examples using an adhesive coating apparatus. A 50 μm thick cyclic polyolefin resin film (manufactured by ZEON Corporation, Japan, trade name "ZEONOR") was then laminated onto each of the adhesive compositions (x1) to (x8) using rollers. The total cumulative light intensity (cumulative light intensity in the wavelength region of 320 to 400 nm) irradiated from the cyclic polyolefin resin film side was approximately 200 mJ / cm². 2 (Measurement values ​​obtained using a Fusion UV Corporation "UV Power Puck II") Ultraviolet light (UVB) was used to harden the coating layer, resulting in a laminate with a layered structure of PMMA film / first adhesive layer / cyclic polyolefin resin film. The thickness of the hardened first adhesive layer was approximately 5 μm. Then, the cyclic polyolefin resin film was peeled off to obtain a moisture permeability test sample with a layered structure of PMMA film / first adhesive layer. For the moisture permeability test sample, the moisture permeability [g / (m³)] was measured at a temperature of 40°C and a relative humidity of 90%RH using the cup method specified in JIS Z 0208. 2 • 24hr). In the measurement, the first adhesive layer of the sample used for moisture permeability testing was installed on the cup with the first adhesive layer facing outwards at an environment of 40°C and 90% RH. Furthermore, for the PMMA film, the moisture permeability measured at 40°C and 90% RH using the same method was 65 g / (m²). 2 • 24hr). The results are presented in Table 1. [Table 1] 1:Polarizing plate 10: Polarizing film 11: First protective film (protective film) 15: First adhesive layer (adhesive layer)

Claims

1. A polarizing plate comprising, sequentially laminated, a polarizing film, an adhesive layer, and a protective film, wherein the adhesive layer is a cured layer of an adhesive composition, the adhesive composition comprising a curing component and a photocationic polymerization initiator (D), the curing component comprising: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq to 155 g / eq, a second aromatic epoxy compound (B) with an epoxy equivalent of greater than 155 g / eq and less than 1000 g / eq, and an oxobutane compound (C) having at least one oxobutane group within its molecule, wherein, in the aforementioned adhesive composition, the content of the first aromatic epoxy compound (A) is 5.0% to 40.0% by mass out of 100% by mass of the total curing component. In the total mass percentage of the aforementioned curing components, the content of the aforementioned second aromatic epoxy compound (B) is 25.0% to 60.0% by mass; in the total mass percentage of the aforementioned curing components, the content of the aforementioned cyclobutane compound (C) is 10.0% to 60.0% by mass; and relative to the total mass percentage of the aforementioned curing components, the content of the aforementioned photocationic polymerization initiator (D) is 0.5% to 10.0% by mass.

2. The polarizing plate as described in claim 1, wherein, In the aforementioned adhesive composition, the mixing ratio of the first aromatic epoxy compound (A) and the second aromatic epoxy compound (B) (first aromatic epoxy compound (A) / second aromatic epoxy compound (B)) is 0.1 to 1.4 or less.

3. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned second aromatic epoxy compound (B) is at least one of bisphenol A type epoxy compounds and bisphenol F type epoxy compounds.

4. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned cyclobutane compound (C) is a monofunctional cyclobutane compound containing one intramolecular cyclobutane group.

5. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned cyclobutane compound (C) contains 3-[(benzylmethyloxy)methyl]-3-ethylcyclobutane, wherein in 100% by mass of the aforementioned curing components, the content of the aforementioned 3-[(benzylmethyloxy)methyl]-3-ethylcyclobutane is 5.0% by mass or more and 40.0% by mass or less.

6. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned curing components further include alicyclic epoxy compounds (E).

7. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned polarizer is a polyvinyl alcohol resin film with dichroic pigments adsorbed and oriented.

8. The polarizing plate as described in claim 1 or 2, wherein, The aforementioned protective film is a (meth)acrylic resin film.

9. An adhesive composition for polarizing plates, comprising a curing component and a photocationic polymerization initiator (D), wherein, The aforementioned curing components comprise: a first aromatic epoxy compound (A) with an epoxy equivalent of 100 g / eq to 155 g / eq; a second aromatic epoxy compound (B) with an epoxy equivalent of greater than 155 g / eq and less than 1000 g / eq; and an oxobutane compound (C) having at least one oxobutane group within its molecule. In the aforementioned adhesive composition for polarizing plates, in 100% by mass of the aforementioned curing components, the content of the first aromatic epoxy compound (A) is 5.0% by mass to 40.0% by mass; in 100% by mass of the aforementioned curing components, the content of the second aromatic epoxy compound (B) is 25.0% by mass to 60.0% by mass; and in 100% by mass of the aforementioned curing components, the content of the oxobutane compound (C) is 10.0% by mass to 60.0% by mass. The content of the aforementioned photocationic polymerization initiator (D) is 0.5% to 10.0% by mass relative to 100% by mass of the total mass of the aforementioned curing components.

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