JP7386896B2 - Photocurable adhesive compositions, photocurable adhesives, polarizing plates and optical equipment - Google Patents

Description

The present invention relates to the field of optical materials, and specifically relates to a photocurable adhesive composition, a photocurable adhesive, a polarizing plate, and optical equipment.

In recent years, liquid crystal display devices have been widely applied to various display devices due to their characteristics such as low power consumption, low voltage operation, light weight edness, and miniaturization. A liquid crystal display device can include many components, such as a liquid crystal cell, a polarizing plate, a retardation film, a prism sheet, a light diffusion film, a light guide plate, and a light reflection sheet. Therefore, efforts are being made to improve productivity and brightness by reducing the number of films used or making films and sheets thinner, and by making liquid crystal display devices lighter.

A polarizing plate includes a polarizer manufactured from polyvinyl alcohol (PVA) resin dyed with a dichroic dye or iodine, and a protective film laminated on one or both surfaces of the polarizer. Install adhesive between the protective film. Triacetyl cellulose (TAC) films are widely used as protective films. However, the TAC film has the drawback of being deformed in high temperature and high humidity environments. Therefore, instead of TAC film, protective films manufactured from various materials have been developed, and polyethylene terephthalate (PET) film, cycloolefin polymer (COP) film, and acrylic film are used alone or in combination with these films. Concepts for film combinations are being proposed one after another.

Acrylic adhesives, dry lamination adhesives obtained by mixing polyurethane resin solutions and polyisocyanate resin solutions, styrene/butadiene/rubber adhesives, epoxy adhesives, polyvinyl alcohol adhesives, polyurethane adhesives, polyester ionomer type polyurethane resins Adhesives such as adhesives and thermosetting adhesives containing compounds having glycidyl and glycidyl groups are constantly being developed. However, the adhesion of these adhesives to different films is a factor that should be taken into consideration, as well as the viscosity of the composition, the thickness that can be produced, acid resistance, alkali resistance, and heat resistance. be.

Therefore, various oxetane monomers have been developed, and these oxetane compounds generally have properties such as low viscosity, weak toxicity, fast polymerization rate, thermal stability, and excellent mechanical properties, and are suitable for cationic curing systems. When applied, it can increase the polymerization rate and improve the performance of the cured product. However, this type of monomer still has obvious shortcomings in practical applications in that there are only a few types of commercially available compounds and it is difficult to balance the overall properties such as curing speed and hardness, especially in polarizing plates. In applications, the adhesion of the entire system becomes a problem after the introduction of oxetanes and requires further optimization.

The present invention provides a photocurable adhesive composition, a photocurable adhesive, a polarizing plate, and an optical equipment, and aims to solve the problem of insufficient adhesion of photocurable adhesives in the prior art. do.

［式（ａａ）中、Ｒがフェニル基、ビフェニル基、ナフチル基を表す。０≦ｎ≦４である。］
前記成分（Ｂ）は、エポキシ基を有する化合物であり、
前記成分（Ｃ）は、光カチオン重合開始剤である。 In order to achieve the above object, one aspect of the present invention provides a photocurable adhesive composition comprising a component (A), a component (B), and a component (C), wherein the component (A) is an oxetane compound containing a structure represented by formula (aa),

[In formula (aa), R represents a phenyl group, a biphenyl group, or a naphthyl group. 0≦n≦4. ]
The component (B) is a compound having an epoxy group,
The component (C) is a photocationic polymerization initiator.

である。 Furthermore, the component (A) is

It is.

Further, the component (B) includes a component (B1) which is a polyglycidyl ether of a polyol having 2 to 10 carbon atoms, and a component (B2) which is a polymer having an epoxy group.

Furthermore, the component (B1) includes ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dimethylol Cyclohexane diglycidyl ether, 1,9-nonanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, hydroquinone diglycidyl ether, resorcinol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tri- or tetraglycidyl It is one or more selected from the group consisting of ethers and di- or triglycidyl ethers of ethylene oxide adducts of isocyanuric acid.

Furthermore, the component (B2) has a Tg of 20° C. or higher and a Mw of 1,000 to 30,000, preferably 3,000 to 20,000, more preferably 5,000 to 15,000, and the Mw is the molecular weight measured by GPC of polystyrene. This is the weight average molecular weight obtained by conversion.

The component (B2) is obtained by polymerization from monomer (b1), monomer (b2), and optionally used monomer (b3). The monomer (b1) is a compound having an epoxy group and an ethylenically unsaturated group, and the ethylenically unsaturated group is a vinyl group or an acryloyl group. Preferably, the monomer (b1) is a glycidyl acrylate, Glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, or 3,4-epoxycyclohexyl methacrylate. The monomer (b2) is a monofunctional methacrylate having a hydrocarbon group having 1 to 10 carbon atoms, and preferably the monomer (b2) is methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate. , sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate, and benzyl One or more types selected from the group consisting of methacrylates. The monomer (b3) is an alkenyl compound different from the monomer (b1), and preferably the monomer (b3) is an aromatic group-containing vinyl compound, a monofunctional acrylate, acrylonitrile, methacrylonitrile, acrylamide, and one selected from the group consisting of methacrylamide, the aromatic group-containing vinyl compound is styrene or α-methylstyrene, and the monofunctional acrylate is methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl From acrylate, sec-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, benzyl acrylate One or more types selected from the group consisting of:

Furthermore, the component (B2) contains, in weight percent, 10 to 60% by weight of the monomer (b1), 10 to 70% by weight of the monomer (b2), and 0 to 60% by weight of the monomer (b3). .

Furthermore, the component (C) is one type or a combination of various types selected from the group consisting of iodonium salts, sulfonium salts, and arylferrocene salts.

Furthermore, when based on the photocurable adhesive composition, the content of the component (A) is 25 to 55% by weight, preferably 25 to 45% by weight, and the content of the component (B1) is The content of component (B2) is 20 to 80% by weight, and the content of component (C) is 3 to 5% by weight.

According to another aspect of the present invention, there is provided a photocurable adhesive obtained by polymerization from a photocurable adhesive composition. The photocurable adhesive composition is any one of the photocurable adhesive compositions described above.

According to another aspect of the present invention, there is provided a polarizing plate including a polarizer and a protective film adhered to the polarizer via an adhesive. The adhesive is the photocurable adhesive described above.

According to another aspect of the invention, an optical equipment including a polarizing plate is provided. The polarizing plate is the polarizing plate described above.

According to the technical proposal of the present invention, by selecting a specific oxiquitane compound and using it in combination with a compound having an epoxy group and a photocationic polymerization initiator, the adhesive strength of the resulting photocurable adhesive, Curability and adhesion to polarizers and protective films are improved.

Note that, unless there is a contradiction, the embodiments of the present invention and the features in the embodiments can be combined with each other. Hereinafter, the present invention will be explained in detail with reference to Examples.

As analyzed in the background art of the present invention, oxetane compounds in the prior art generally have characteristics such as low viscosity, weak toxicity, fast polymerization rate, thermal stability, and excellent mechanical properties. However, during actual application, there is still a problem in that it is difficult to balance curing speed and hardness. Especially when applied to polarizing plates, the overall adhesion effect of the adhesive is not ideal after the introduction of oxetane compounds. In order to solve this problem, the present invention provides a photocurable adhesive composition, a photocurable adhesive, a polarizing plate, and optical equipment.

［式（ａａ）中、Ｒがフェニル基、ビフェニル基、ナフチル基を表す。０≦ｎ≦４である。］
成分（Ｂ）は、エポキシ基を有する化合物であり、成分（Ｃ）は、光カチオン重合開始剤である。 In one exemplary embodiment of the present invention, there is provided a photocurable adhesive composition comprising component (A), component (B) and component (C), wherein component (A) has the formula (aa): An oxetane compound containing the structure shown,

[In formula (aa), R represents a phenyl group, a biphenyl group, or a naphthyl group. 0≦n≦4. ]
Component (B) is a compound having an epoxy group, and component (C) is a cationic photopolymerization initiator.

The present invention improves the adhesion, curability, and polarization of the resulting photocurable adhesive by selecting a specific oxiquitane compound and using it in combination with a compound having an epoxy group and a photocationic polymerization initiator. Improved adhesion to the child and protective film.

である場合、効果がより明らかである。 As a result of testing, the component (A) is:

, the effect is more obvious.

In one embodiment of the present invention, the component (B) includes component (B1) and component (B2). Component (B1) is a polyglycidyl ether of a polyol having 2 to 10 carbon atoms, and component (B2) is a polymer having an epoxy group. By blending the above two types of epoxy group-containing compounds and further blending with an oxetane compound, the adhesiveness of the photocurable adhesive is further improved.

Preferably, the component (B1) is ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, di- Methylolcyclohexane diglycidyl ether, 1,9-nonanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, hydroquinone diglycidyl ether, resorcinol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tri- or tetra One or more types selected from the group consisting of glycidyl ether and di- or triglycidyl ether of an ethylene oxide adduct of isocyanuric acid.

In order to improve the workability of applying the photocurable adhesive and to ensure adhesiveness, the component (B2) must have a Tg of 20° C. or higher (same as the general measurement method of the prior art, that is, The value measured using a differential scanning calorimeter (DSC) at a heating rate of 10° C./min), and the Mw is preferably 1000 to 30000, preferably 3000 to 20000, more preferably 5000 to 15000. be. Here, Mw is the weight average molecular weight obtained by converting the molecular weight measured by GPC into polystyrene. When the Mw of the component (B2) is less than 1,000, the effect of improving the adhesive force between the polarizer and the protective film is not obvious, and when the Mw exceeds 30,000, the applicability decreases, making installation difficult. Increase.

In one embodiment of the invention, component (B2) is obtained by polymerization from monomer (b1), monomer (b2) and optionally used monomer (b3). Component (B2) is a low Mw polymer. If it is desired to make such polymers by conventional polymerization methods, it is usually necessary to increase the chain transfer agent and/or polymerization initiator. When forming a polymer using a large amount of chain transfer agent, the cationic curability and/or adhesive strength of the composition tends to decrease, and the storage stability of the composition also tends to decrease. Therefore, preferably, the monomer (b1) is a compound having an epoxy group and an ethylenically unsaturated group, and the ethylenically unsaturated group is a vinyl group or an acryloyl group. Preferably, monomer (b1) is glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, or 3,4-epoxycyclohexyl methacrylate. Monomer (b2) is a monofunctional methacrylate having a hydrocarbon group having 1 to 10 carbon atoms, preferably methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, tert- Any member selected from the group consisting of butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate, and benzyl methacrylate. or one or more types. Monomer (b3) is an alkenyl compound different from monomer (b1), and is preferably selected from the group consisting of aromatic group-containing vinyl compounds, monofunctional acrylates, acrylonitrile, methacrylonitrile, acrylamide, and methacrylamide. Either one is one of them. The aromatic group-containing vinyl compound is styrene or α-methylstyrene. Monofunctional acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl It is one or more selected from the group consisting of acrylate, nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, and benzyl acrylate. This avoids problems with high temperature polymerizations that employ large amounts of chain transfer agents and/or polymerization initiators.

The monomer (b1) and monomer (b2) are copolymerized as essential monomer units with component (B1) and component (A), which are cationic curable compounds. Furthermore, the monomer (b1) is particularly preferably glycidyl methacrylate, and the monomer (b2) is particularly preferably one or more selected from the group consisting of methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. . From the viewpoint of adjusting reactivity, system viscosity, etc., monomer (b3) can be further added.

Preferably, in % by weight, component (B2) comprises 10 to 60 % by weight of monomer (b1), 10 to 70 % by weight of monomer (b2) and 0 to 60 % by weight of monomer (b3). When monomer (b3) contains styrene, the content of styrene in component (B2) is 5 to 45% by weight, preferably 10 to 40% by weight. When the monomer (b3) contains a monofunctional acrylate, the content of the monofunctional acrylate in component (B2) is 1 to 30% by weight, preferably 5 to 25% by weight. Preferably, component (B2) contains methyl methacrylate as monomer (b2) with a content of 10 to 70% by weight, and contains styrene as monomer (b3) with a content of 1 to 50% by weight. . Preferably, component (B2) comprises glycidyl methacrylate having a content of 10 to 60% by weight as monomer (b1), methyl methacrylate having a content of 10 to 70% by weight as monomer (b2), and monomer (b2) having a content of 10 to 70% by weight. b3) contains a monofunctional acrylate having a hydrocarbon group having 1 to 10 carbon atoms in a content of 1 to 30% by weight. By adjusting the amount of styrene or monofunctional acrylate used, the activity, viscosity, volume shrinkage rate of the reaction system containing the composition, and stability of the formed adhesive can be further adjusted.

［ここで、
Ｒ_１とＲ_２は、それぞれ独立的に水素、Ｃ_１－Ｃ_２０の直鎖又は分岐アルキル基、Ｃ_４－Ｃ_２０のシクロアルキルアルキル基又はアルキルシクロアルキル基を表し、また、これらの基における非環式－ＣＨ_２－は、－Ｏ－、－Ｓ－又は１，４－フェニレン基で置換されてもよい。
Ｒ_３とＲ_４は、それぞれ独立的に水素、Ｃ_１－Ｃ_２０の直鎖又は分岐アルキル基、Ｃ_４－Ｃ_２０のシクロアルキルアルキル基又はアルキルシクロアルキル基、Ｃ_６－Ｃ_２０の置換又は非置換アリール基を表し、また、これらの基における非環式－ＣＨ_２－は、－Ｏ－、－Ｓ－又は１，４－フェニレン基で置換されてもよい。
Ｒ_５は、Ｃ_６－Ｃ_２０の置換又は非置換アリール基、Ｃ_６－Ｃ_２０の置換又は非置換アルキルアリール基、Ｃ_１－Ｃ_２０の直鎖又は分岐アルキル基、Ｃ_４－Ｃ_２０のシクロアルキルアルキル基又はアルキルシクロアルキル基、置換又は非置換のフェニルチオフェニル基を表し、また、これらの基における非環式－ＣＨ_２－は、カルボニル基、－Ｏ－、－Ｓ－又は１，４－フェニレン基で置換されてもよい。
Ｒ_６とＲ_７は、それぞれ独立的にアルキル基、ヒドロキシ基、アルコキシ基、アルキルカルボニル基、アリールカルボニル基、アルコキシカルボニル基、アリールオキシカルボニル基、アリールチオカルボニル基、アシルオキシ基、アリールチオ基、アリール基、複素環式炭化水素基、アリールオキシ基、アルキルスルフィニル基、アリールスルフィニル基、アルキルスルホニル基、アリールスルホニル基、ヒドロキシ（ポリ）アルキレンオキシ基、置換してもよいアミノ基、シアノ基、ニトロ基又はハロゲン原子を表す。
ｍ１、ｍ２は、それぞれ独立的に、Ｒ_６とＲ_７の個数を表し、０、１、２、３、又は４から選ばれる。
Ｘ^－は、それぞれ独立的に、Ｍ^－、ＣｌＯ_４ ^－、ＣＮ^－、ＨＳＯ_４ ^－、ＮＯ_３ ^－、ＣＦ_３ＣＯＯ^－、(ＢＭ_４) ^－、(ＳｂＭ_６) ^－、(ＡｓＭ_６) ^－、(ＰＭ_６) ^－、Ａｌ[ＯＣ(ＣＦ_３)_３]_４ ^－、スルホン酸イオン、Ｂ(Ｃ_６Ｍ_５)_４ ^－、又は[(Ｒｆ)_ｂＰＦ_６－b] ^－を表す。その中、Ｍはハロゲンであり、Ｒｆはそれぞれ独立的に水素原子の８０％以上がフッ素原子に置換されたアルキル基を表し、ｂは１～５の整数を表す。］ In one embodiment of the present invention, the component (C) is one or a combination of various selected from the group consisting of iodonium salts, sulfonium salts, and arylferrocene salts. Preferably, the component (C) is a compound having a structure represented by the following formula (I) and/or (II).

[here,
R ₁ and R ₂ each independently represent hydrogen, a C ₁ -C ₂₀ linear or branched alkyl group, a C ₄ -C ₂₀ cycloalkylalkyl group or an alkylcycloalkyl group, and Acyclic -CH ₂ - may be substituted with -O-, -S- or 1,4-phenylene group.
R ₃ and R ₄ are each independently hydrogen, a C ₁ -C ₂₀ linear or branched alkyl group, a C ₄ -C ₂₀ cycloalkylalkyl group or an alkylcycloalkyl group, a C ₆ -C ₂₀ substituted or It represents an unsubstituted aryl group, and the acyclic -CH ₂ - in these groups may be substituted with -O-, -S- or 1,4-phenylene group.
R ₅ is a C ₆ -C ₂₀ substituted or unsubstituted aryl group, a C ₆ -C ₂₀ substituted or unsubstituted alkylaryl group, a C ₁ -C ₂₀ linear or branched alkyl group, a C ₄ -C ₂₀ It represents a cycloalkylalkyl group or an alkylcycloalkyl group, a substituted or unsubstituted phenylthiophenyl group, and the acyclic -CH ₂ - in these groups represents a carbonyl group, -O-, -S- or 1, It may be substituted with a 4-phenylene group.
R ₆ and R ₇ each independently represent an alkyl group, a hydroxy group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an arylthiocarbonyl group, an acyloxy group, an arylthio group, an aryl group , heterocyclic hydrocarbon group, aryloxy group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, hydroxy(poly)alkyleneoxy group, optionally substituted amino group, cyano group, nitro group, or Represents a halogen atom.
m1 and m2 each independently represent the number of R ₆ and R ₇ and are selected from 0, 1, 2, 3, or 4.
X ⁻ is each independently M ⁻ , ClO ₄ ⁻ , CN ⁻ , HSO ₄ ⁻ , NO ₃ ⁻ , CF ₃ COO ⁻ , (BM ₄ ) ⁻ , (SbM ₆ ) ⁻ , (AsM ₆ ) ⁻ , (PM ₆ ) ⁻ , Al[OC(CF ₃ ) ₃ ] ₄ ⁻ , sulfonic acid ion, B(C ₆ M ₅ ) ₄ ⁻ , or [(Rf) _b PF _6-b ] ⁻ . Among them, M is a halogen, Rf each independently represents an alkyl group in which 80% or more of hydrogen atoms are substituted with fluorine atoms, and b represents an integer of 1 to 5. ]

By employing the above substance as a photocationic polymerization initiator, the curing rate of the photocurable adhesive composition can be increased.

As a preferred structure, in the compounds represented by formulas (I) and (II), R ₁ and R ₂ each independently represent hydrogen, a C ₁ -C ₁₂ linear or branched alkyl group, or a C ₄ -C ₁₀ alkyl group. Represents a cycloalkylalkyl group or an alkylcycloalkyl group, and the acyclic -CH ₂ - in these groups may be substituted with -O-; R ₃ and R ₄ each independently represent hydrogen, C ₁ -C ₁₀ straight chain or branched alkyl group, C ₄ -C ₁₀ cycloalkylalkyl group or alkylcycloalkyl group, C ₆ -C ₁₂ substituted or unsubstituted aryl group; Cyclic -CH ₂ - may be substituted with -O-, -S- or 1,4-phenylene; R ₅ is a C ₆ -C ₁₀ substituted or unsubstituted aryl group, a C ₆ -C ₁₀ It represents a substituted or unsubstituted alkylaryl group, a substituted or unsubstituted phenylthiophenyl group, and the acyclic -CH ₂ - in these groups represents a carbonyl group, -O-, -S- or 1,4-phenylene. may be substituted with a group; R ₆ and R ₇ are a C ₁ -C ₁₀ straight chain or branched alkyl group, a C ₁ -C ₁₀ straight chain or branched alkoxy group, a C ₁ -C ₁₀ alkylcarbonyl group , and represents a halogen.

Commercially available photocationic initiators with similar structures can also be used as component (C) of the present invention. Examples include (but are not limited to) PAG20001, PAG20001s, PAG20002, PAG20002s, PAG30201, PAG30101 (all of the above are manufactured by the company Trnoloy), Irgacure 250 (manufactured by BASF), and the like.

In the photocurable adhesive composition of the present invention, as the usage amount of each component, the usage amount of the corresponding component in the prior art can be referred to. Preferably, the content of component (A) is 25 to 60% by weight, preferably 25 to 55% by weight, more preferably 25 to 45% by weight, based on the photocurable adhesive composition; The content of (B1) is 10 to 45% by weight, preferably 10 to 35% by weight; the content of component (B2) is 15 to 80% by weight, preferably 20 to 80% by weight, more preferably 15 to 80% by weight. 35% by weight; the content of component (C) is 3 to 5% by weight, preferably 5% by weight.

Depending on the needs of the product application, the photocurable adhesive of the present invention may contain organic and/or inorganic auxiliaries commonly used in this field, such as leveling agents, dispersants, curing agents, surfactants. , a solvent, etc. may be added, but the auxiliary agent is not limited to these. This is obvious to those skilled in the art. Furthermore, other sensitizers and/or photoinitiators may also be added to the adhesive for use, provided that they do not adversely affect the application effectiveness of the composition.

According to application needs, one or more large molecules or polymer compounds can be selectively added to the photocurable adhesive to enhance the application performance, and it does not contain any reactive functional groups. Polymers can be added selectively. This large molecule or polymeric compound may be a polyol or polyester polyol. These polymers are usually resins containing acidic functional groups such as phenolic hydroxyl groups and carboxyl groups.

One typical embodiment of the present invention provides a photocurable adhesive obtained by polymerization from a photocurable adhesive composition. The photocurable adhesive composition is any one of the photocurable adhesive compositions described above.

In the photocurable adhesive composition of the present invention, a specific oxetane compound is selected and used in combination with a compound having an epoxy group and a photocationic polymerization initiator. Adhesion, curability, and adhesion to polarizers and protective films are improved.

Another exemplary embodiment of the invention provides a polarizing plate that includes a polarizer and a protective film adhered to the polarizer via an adhesive. The adhesive is the photocurable adhesive described above. The photocurable adhesive of the present invention has good adhesion, acid resistance, alkali resistance, and excellent thermal stability, so the polarizing plate using it as an adhesive has a long service life and good optical performance. In good condition.

The photocurable adhesive of the present invention can be used to adhere a protective film to a polarizer made of a polyvinyl alcohol resin film, such as polyvinyl alcohol that has been uniaxially stretched and has a dichroic dye adsorbed and oriented. It can be used to adhere a protective film to a polarizer made of a resin film. Thereby, a polarizing plate is produced by attaching the protective film to the polarizer. The protective film can be attached to one side of the polarizer, or can be attached to both sides of the polarizer. When the protective films are attached to both sides of the polarizer, each protective film may be made of the same type of resin or may be made of different types of resin.

Based on the above application of the invention, polarizing plates can be manufactured by conventional processes in the field. Typically, the manufacturing method includes attaching a protective film to one or both sides of a polarizer via a photocurable adhesive, and curing the photocurable adhesive by light irradiation.

The specific process includes the following steps.
(1) Coating process: The photocurable adhesive is applied to the protective film in an uncured state to form the adhesive coated surface.
(2) Attaching process: Attach the polarizer to the adhesive-coated surface of the protective film.
(3) Curing process: The photocurable adhesive is cured by light irradiation to form an adhesive layer.

During the manufacturing process of the polarizing plate, a protective film can be attached to one side, or a protective film can be attached to both sides. Preferably, at least one of the protective films on both sides also has other optical functions.

As the polarizer, it is possible to use a type commonly used in this field, such as a uniaxially stretched polyvinyl alcohol resin film on which iodine or dichroic dye is adsorbed and oriented.

Another exemplary embodiment of the invention provides an optical equipment that includes a polarizer. The polarizing plate is the polarizing plate described above.

In actual use, a polarizing plate may be manufactured as an optical member obtained by laminating an optical layer exhibiting an optical function other than a polarizing function on one side of the polarizing plate. Regarding optical members, depending on the purpose of use, one or more optical layers selected from a polarizing plate and the above-mentioned reflective layer or semi-transparent reflective layer, light scattering layer, retardation plate, light condensing plate, brightness enhancement film, etc. A laminate of two layers, three layers or more can be produced by combining the layers. Various optical layers forming an optical member are integrated with a polarizing plate using an adhesive. A liquid crystal display device can be manufactured by arranging the above optical members on one or both sides of a liquid crystal cell.

The present invention will be explained in more detail with reference to the following examples, but is not limited to these examples.

1. Preparation of photocurable adhesive Referring to the recipe shown in the table, the raw materials were mixed uniformly to obtain a photocurable adhesive composition (unless otherwise specified, all "parts" are "mass"). ).

2. Performance evaluation The photocurable adhesives prepared in Examples and Comparative Examples were subjected to defoaming treatment, and coated with a triacetyl cellulose (TAC) protective film (80 μm thick) using a bar coater so that the coating film thickness was 10 μm. (trade name: Fujitech, Fuji Film Company), and then attached to one side of a polyvinyl alcohol-iodine polarizer. Next, the same adhesive was applied to the other side of the polarizer so that the thickness of the coating film was 10 μm, and a norbornene resin film (trade name: ZEONOR, manufactured by OPTES Company) was attached. Next, curing was carried out using a mercury lamp (exposure machine part number RW-UV20101, which received a cumulative radiant energy of 2000 mJ/cm ² ).

Adhesion, curing performance and adhesive performance were evaluated, and the specific evaluation methods and standards are as follows.

(1) Adhesion force The adhesion force was measured with an ARCOTEST dyne pen, and specifically, the number of the highest numbered dyne pen that distributed the lines evenly and did not cause the ink to form droplets within 3 seconds was taken as the measured value. The smaller the surface dyne value, the greater the surface tension of the lower layer to which it is attached, which is advantageous for adhesion.

(2) Adhesiveness The adhesiveness of different protective films on both sides (ie, TAC film and norbornene film) was evaluated as follows.
A: The protective film cannot be peeled off from the polarizer at the interface, and if it is forcibly removed, the film will be damaged. That is, the adhesive property is excellent.
B: The protective film can be peeled off from the polarizer at the interface without damaging the film. That is, the adhesive property is good.
C: Immediately after curing, the adhesive is floating or not adhered at all. That is, the adhesiveness is poor.

(3) Curability The TAC film and norbornene film were peeled off from the polarizer, and the surface condition of the cured film was observed with reference to the GB1728-79 surface drying time measurement method - finger touch method, and evaluated as follows. .
A: There is no sticky situation. That is, the curability is good.
B: There is a sticky situation. That is, the curability is poor.

3. Specific prescription and evaluation results Example 1
Preparation of different compositions when R in component (A) is a phenyl group
Component (A) (specifically refer to Table 1) 25 parts by mass Component (B1): 35 parts by mass of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate Component (B2): Glycidyl methacrylate/methyl methacrylate /obtained from hydroxyethyl acrylate by heating polymerization (mass ratio 30:40:30, Mw 12000) 35 parts by mass Component (C):

From the results in Table 1, it can be seen that when n=1, the curing effect is good, the adhesion is good, and the adhesion to the TAC film and norbornene film is excellent.

Example 2
Preparation of different compositions when R in component (A) is a biphenyl group
Component (A) (specifically refer to Table 2) 35 parts by mass Component (B1): 25 parts by mass of 3,4-epoxycyclohexylmethyl-3,4- epoxycyclohexylcarboxylate Component (B2): Glycidyl methacrylate/methyl methacrylate /obtained from hydroxyethyl acrylate by heating polymerization (mass ratio 30:40:30, Mw 12000) 35 parts by mass Component (C):

From the results in Table 2, it can be seen that when n=1, the curing effect is good, the adhesion is good, and the adhesion to the TAC film and norbornene film is excellent.

成分（Ａ）（具体的に表３を参照） ４０質量部
成分（Ｂ１）：ペンタエリスリトールテトラグリシジルエーテル ３０質量部
成分（Ｂ２）：グリシジルメタクリレート/メチルメタクリレート/アクリル酸ヒドロキシエチルから加熱重合により得られたもの（質量比３０：４０：３０、Ｍｗは１２０００） ２５質量部
成分（Ｃ）：

Example 3
Preparation of different compositions when R in component (A) is a naphthyl group

Component (A) (see Table 3 for details) 40 parts by mass Component (B1): Pentaerythritol tetraglycidyl ether 30 parts by mass Component (B2): Obtained from glycidyl methacrylate/methyl methacrylate/hydroxyethyl acrylate by heating polymerization (mass ratio 30:40:30, Mw 12000) 25 parts by mass Component (C):

From the results in Table 3, it can be seen that when n=1, the curing effect is good, the adhesion is good, and the adhesion to the TAC film and norbornene film is excellent.

Other compounds where n=1 were selected and their weight ratios in the adhesive composition were changed to evaluate their application performance. The results are shown in Table 4.

From the performance evaluation results in Tables 1 to 3 and Table 5, it can be seen that the adhesive composition of the present invention has good curing effect, good adhesion, and excellent adhesion to TAC film and norbornene film. The reason is that in the formulation containing the composition of the present invention, the oxetane compound contains a monofunctional oxygen heterocycle, has an appropriate viscosity, and the benzyl group in the group accelerates the curing rate, so it has excellent overall application. It is assumed that it has the performance.

The above description is only a preferred embodiment of the invention and is not intended to limit the invention. Various modifications and variations of the present invention will occur to those skilled in the art. All changes, equivalent conversions, improvements, etc. within the spirit and principles of the present invention are intended to be included within the protection scope of the present invention.

Claims (16)

A photocurable adhesive composition comprising a component (A), a component (B), and a component (C),
The component (A) is an oxetane compound containing a structure represented by formula (aa),
[In formula (aa), R represents a biphenyl group or a naphthyl group. n=1. ]
The component (B) is a compound having an epoxy group, and the component (C) is a cationic photopolymerization initiator,
The component (B) is
A component (B1) which is a polyglycidyl ether of a polyol having 2 to 10 carbon atoms or 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, and
Component (B2) which is a polymer having an epoxy group (excluding the above component (B1))
including;
When based on the photocurable adhesive composition,
The content of the component (A) is 25 to 55% by weight,
The content of the component (B1) is 10 to 45% by weight,
The content of the component (B2) is 20 to 80% by weight, and
The content of the component (C) is 3 to 5% by weight,
Photocurable adhesive composition. The component (A) is
The photocurable adhesive composition according to claim 1, characterized in that: The component (B1) is ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dimethylolcyclohexane di Glycidyl ether, 1,9-nonanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, hydroquinone diglycidyl ether, resorcinol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tri- or tetraglycidyl ether, The photocurable adhesive composition according to claim 1 , characterized in that the photocurable adhesive composition is one or more selected from the group consisting of: and di- or triglycidyl ether of an ethylene oxide adduct of isocyanuric acid. The component (B2) has a Tg of 20°C or higher and a Mw of 1000 to 30000,
The photocurable adhesive composition according to claim 1 , wherein the Mw is a weight average molecular weight obtained by converting the molecular weight measured by GPC into polystyrene. The photocurable adhesive composition according to claim 4 , wherein the component (B2) has an Mw of 3,000 to 20,000. The photocurable adhesive composition according to claim 4 , wherein the component (B2) has an Mw of 5,000 to 15,000. The photocurable adhesive composition according to claim 1 , characterized in that the component (B2) is obtained by polymerization from monomer (b1), monomer (b2), and optionally used monomer (b3). And,
The monomer (b1) is a compound having an epoxy group and an ethylenically unsaturated group, and the ethylenically unsaturated group is a vinyl group or an acryloyl group,
The monomer (b2) is a monofunctional methacrylate having a hydrocarbon group having 1 to 10 carbon atoms,
A photocurable adhesive composition, wherein the monomer (b3) is an alkenyl compound different from the monomer (b1). The photocurable adhesive composition according to claim 7 , wherein the monomer (b1) is glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, or 3,4-epoxycyclohexyl methacrylate. . The monomer (b2) is methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate. , isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate , and benzyl methacrylate. thing. The monomer (b3) is any one selected from the group consisting of aromatic group-containing vinyl compounds, monofunctional acrylates, acrylonitrile, methacrylonitrile, acrylamide, and methacrylamide,
The aromatic group-containing vinyl compound is styrene or α-methylstyrene, and the monofunctional acrylate is methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, It is characterized by being one or more selected from the group consisting of isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, and benzyl acrylate. The photocurable adhesive composition according to claim 7 . The component (B2) contains, by weight, 10 to 60% by weight of the monomer (b1), 10 to 70% by weight of the monomer (b2), and 0 to 60% by weight of the monomer (b3). The photocurable adhesive composition according to claim 7 , characterized in that: The photocurable adhesive composition according to claim 1, wherein the component (C) is a combination of one or more selected from the group consisting of iodonium salts, sulfonium salts, and arylferrocene salts. When based on the photocurable adhesive composition,
The photocurable adhesive composition according to claim 1 , characterized in that the content of the component (A) is 25 to 45% by weight. A photocurable adhesive obtained by polymerization from the photocurable adhesive composition according to any one of claims 1 to 13 . A polarizing plate comprising a polarizer and a protective film adhered to the polarizer via an adhesive,
A polarizing plate, wherein the adhesive is the photocurable adhesive according to claim 14 . Optical equipment including a polarizing plate,
An optical equipment characterized in that the polarizing plate is the polarizing plate according to claim 15 .