TWI607074B - Photocurable adhesive composition, polarizing adhesive and manufacturing method therefor, optical member and liquid crystal display device - Google Patents

Description

Photocurable adhesive composition, polarizing plate, manufacturing method thereof, optical member, and liquid crystal display device

The present invention relates to a photocurable adhesive composition used for bonding a polarizing film and a protective film in a polarizing plate, a polarizing plate in which a protective film is bonded to a polarizing film using the adhesive composition, and the production of the polarizing plate. method. The present invention is also related to an optical member and a liquid crystal display device using the polarizing plate.

The polarizing plate is used as one of optical parts constituting a liquid crystal display device. The polarizing plate is generally used in a liquid crystal display device in a state in which the protective film is applied to the two-layer protective film of the polarizing film. It is also known that a protective film is provided only on one side of the polarizing film, but in most cases, the other layer having the optical function is bonded to the other surface as a protective film, not just as a simple protective film. Further, as a method for producing a polarizing film, a method of treating a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic dye with boric acid and drying it after washing with water is widely known.

In general, the protective film is bonded to the polarizing film immediately after washing and drying as described above. This is because the polarized film after drying has a weak physical strength, and once it is taken up, it may cause problems such as cracking in the processing direction. Therefore, the polarizing film after drying is usually applied with a water-based adhesive immediately, and then the protective film is bonded to both surfaces simultaneously with the adhesive. usually As the protective film, a cellulose triacetate film having a thickness of 30 to 120 μm was used.

In the polarizing film and the protective film, in particular, a polyvinyl alcohol-based adhesive is often used as the adhesive film of the protective film containing the cellulose triacetate film, and an amine-based adhesive is also tried. Japanese Patent Publication No. 7-120617 (Patent Document 1) discloses a polarizing film having a high water content and a cellulose acetate-based protective film, such as cellulose triacetate, using a urethane prepolymer as an adhesive. film.

On the other hand, the cellulose triacetate has a high moisture permeability, and the polarizing plate to which the resin film is bonded as a protective film causes problems such as deterioration under conditions of moist heat such as a temperature of 70 ° C and a relative humidity of 90%. Therefore, a method of solving the above problem by using a resin film having a lower moisture permeability than a cellulose triacetate film as a protective film has been proposed. For example, an amorphous polyolefin resin is known as a protective film. In the above-mentioned Japanese Patent Publication No. Hei 6-51117 (Patent Document 2), a thermoplastic saturated norbornene-based resin sheet having at least one area of a polarizing film is used as a protective film.

When such a low moisture permeability protective film is bonded to a conventional device, even a water-based solvent, such as an aqueous solution of polyvinyl alcohol, is applied to the protective film of the polyvinyl alcohol-based polarizing film after the protective film is applied to the so-called wet laminate. When the solvent is dried, problems such as insufficient adhesion strength or poor appearance may not be obtained. This is because the film having a low moisture permeability is generally more hydrophobic than the cellulose triacetate film or has a low moisture permeability, and the water as a solvent cannot be sufficiently dried.

Therefore, Japanese Laid-Open Patent Publication No. 2000-321432 (Patent Document 3) proposes a polyvinyl alcohol-based polarizing film and a thermoplastic saturated hail. The protective film of the olefinic resin is followed by a polyurethane-based adhesive. However, the polyurethane adhesive has a problem that it takes a long time to harden, and the adhesive force is not necessarily sufficient.

On the other hand, it is also known to apply a different type of protective film to both surfaces of a polarizing film. For example, Japanese Laid-Open Patent Publication No. 2002-174729 (Patent Document 4) proposes a polarizing film comprising a polyvinyl alcohol resin film. A protective film containing an amorphous polyolefin-based resin is bonded to one surface, and a resin different from the amorphous polyolefin-based resin, for example, a protective film of cellulose triacetate, is bonded to the other surface. Japanese Patent Laid-Open No. 2005-208456 In the case of one of the polarizing films containing a polyvinyl alcohol-based resin, it is proposed that a water-based first adhesive layer-containing cycloolefin-based resin film containing a specific urethane resin is interposed on the other side. A water-based second adhesive different from the first adhesive, for example, an aqueous solution of a polyvinyl alcohol-based resin, is laminated with a cellulose acetate-based resin film.

In the above-mentioned Patent Document 4, it is referred to as "amorphous polyolefin-based resin", and in the above-mentioned Patent Document 5, it is referred to as "cycloolefin-based resin", and it is intended to contain, for example, norbornene or a derivative thereof. When a monomer unit of a polycyclic cyclic olefin such as dimethanoocta hydronaphthalene is used, and a double bond remains as in the case of a ring-opening polymer, a hydrogenated thermoplastic resin is preferably used.

Further, Japanese Laid-Open Patent Publication No. 2004-245925 (Patent Document 6) discloses an adhesive containing an epoxy resin containing no aromatic ring as a main component, and proposes a cation by irradiating the adhesive with an active energy ray. A method of polymerizing followed by a polarizing film and a protective film. The epoxy-based adhesive disclosed herein is suitable for bonding to a polarizing film to form an amorphous polyolefin tree. Various types of transparent resin films, such as fats and cellulose-based resins, are particularly effective. However, in the case where an acrylic resin is used as a protective film, it is known that the adhesion is not necessarily sufficient.

Therefore, the inventors of the present invention performed a protective film having a low moisture permeability of a resin film selected from the group consisting of an acrylic resin, a polyester resin, a polycarbonate resin, and an amorphous polyolefin resin as a polarizing film in a short period of time. The procedure demonstrates the development of a low adhesion, photocurable adhesive with good adhesion. As a result, it has been found that a composition containing a epoxidized propyl ether epoxy resin having an aromatic ring and a propylene oxide compound imparts a good adhesion, particularly in a (meth) acrylate system having an alicyclic skeleton. When the monomer is 5 to 25% by weight, high adhesion and durability can be exhibited (Patent Document 7). However, in this adhesive agent, the production step itself is completed in a short-time step of illuminating, but there is a problem that a sufficient adhesive force cannot be exhibited after a film is taken up without a lapse of a period of time. Therefore, there is a problem that handling of the film after illumination in the production step is difficult.

As a result of various studies to solve the above problems, the present inventors have found that an alicyclic epoxy compound, a specific poly(meth)acrylate, a photocationic polymerization initiator, and an oxetane alcohol are contained. The photocurable adhesive composition is effective (Patent Document 8).

This adhesive composition is not only a photocurable adhesive for polarizing plates, but also excellent in adhesion and durability, and excellent in productivity.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 7-120617

[Patent Document 2] Japanese Patent Laid-Open No. Hei 6-51117

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2000-321432

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2002-174729

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2005-208456

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2004-245925

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2010-209126

[Patent Document 8] Japanese Laid-Open Patent Publication No. 2012-140610

However, it has been confirmed that the adhesive of the aforementioned Patent Document 8 is subjected to a moist heat resistance test in a high-temperature and high-humidity environment (e.g., 60% at 60 ° C), and returned to a general environment (e.g., 23 ° C, 50%), and then the peeling force is extremely low.

In response to this decrease in force, if placed in a general environment for 15 hours, the peeling adhesion force will return to the extent that the protective film is damaged by the material. Further, even after the end of the moist heat resistance test, the force applied to the form of the product in which the polarizing plate is adhered to the glass (the force in the shearing direction or the vertical direction) does not cause peeling of the protective film. However, if it is assumed that after exposure to a high-temperature and high-humidity environment in the transport of the polarizing plate, the worst case of the processing step is immediately entered, and it is expected that the peeling strength will be improved after the end of the moist heat resistance test.

An object of the present invention is to provide a photocurable adhesive which is a resin film having a low moisture permeability selected from a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin. When the film is protected, the adhesion force can be quickly expressed after the light is irradiated. After the time limit, the final adhesion was also good, and the endurance test did not cause problems such as poor appearance, and the adhesion after the end of the damp heat test was good, and the viscosity before hardening was low. Further, a polarizing plate in which a protective film is bonded to a polarizing film using the adhesive is provided. Another object of the present invention is to provide an optical member which can form a liquid crystal display device having excellent reliability by using the polarizing plate, and further applies the same to a liquid crystal display device.

That is, the photocurable adhesive composition of the present invention is used for a polarizing film followed by a protective film, and the polarizing film comprises a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye. The film system includes a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin, and the adhesive composition is characterized by: (A) having intramolecular At least two epoxy compounds of the alicyclic epoxy group represented by the following formula (1);

(B) a poly(meth)acrylate having a carbon number of 2 to 15 polyols; (C) a photocationic polymerization initiator; (D) a propylene oxide compound represented by the following formula (2);

(E) a polymer having a (meth)acrylic acid alkyl ester as an essential constituent monomer unit, and the content ratio of the above components (A) to (E) in the composition is

(A) Composition: 10 to 65 wt%

(B) Composition: 10 to 55% by weight

(C) Component: 0.5 to 10% by weight

(D) Composition: 1 to 25% by weight

(E) component: 0.1 to 25% by weight.

In the composition of the present invention, the component (A) is preferably an epoxy compound represented by the following formula (4).

The component (B) is more preferably a di(meth)acrylate having a diol having 5 to 10 carbon atoms. Further, as the (meth) acrylate, it is more preferably an acrylate.

The preferred content ratio of the component (A) and the component (B) is 10 to 50% by weight and 20 to 45% by weight, respectively, based on the composition.

The component (E) preferably contains a polymer having an alkyl (meth)acrylate containing an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit and having a weight average molecular weight of 1,000 to 500,000.

The polymer preferably contains 60% by weight or more of methyl propyl group. Methyl enoate as a constituent monomer unit, and a polymer having a weight average molecular weight of 1,000 to 200,000 (hereinafter also referred to as "(E1) component"], and containing 60% by weight or more of an alkyl group having 1 to 10 carbon atoms The alkyl acrylate is a polymer constituting a monomer unit and having a weight average molecular weight of 1,000 to 200,000 [hereinafter also referred to as "(E2) component").

The (E2) component is more preferably a polymer obtained by polymerization at a high temperature, and an alkyl acrylate containing 60% by weight or more of an alkyl group having 1 to 10 carbon atoms is used as a constituent monomer unit, and the weight average molecular weight is 1,000. ~200,00 polymer.

Furthermore, in the composition of the present invention, it is preferred that the composition contains 1 to 30% by weight of the propylene oxide compound represented by the formula (3) as the component (F).

The radically polymerizable component such as the component (B) contained in the photocurable adhesive composition can be cured by the radical generated when the component (C) is photodecomposed, but A sufficient amount of irradiation is obtained to obtain a sufficient reaction rate, and a photoradical polymerization initiator containing the component (G) in a proportion of 10% by weight or less is preferable.

As the component (G), the mercaptophosphine oxide compound is preferred because it has excellent adhesion.

Further, in order to obtain a coated surface having excellent smoothness, the photocurable adhesive composition preferably contains 0.01 to 0.5% by weight of a leveling agent of the component (H) in the composition.

Further, the polarizing plate of the present invention is a polarizing plate obtained by laminating a protective film on a polarizing film via an adhesive, and the adhesive comprises a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye. The protective film includes a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin, and the adhesive is polarized by any of the above photocurable adhesive compositions. board.

The polarizing plate can be manufactured by a method comprising the steps of: applying an adhesive coating step to coating at least one of the bonding surfaces of the polarizing film and the protective film, and coating the photocurable adhesive composition; The obtained adhesive layer is bonded to the polarizing film and the protective film, and the curing step is to cure the photocurable adhesive composition in a state where the polarizing film and the protective film are bonded to each other via the adhesive layer. Specifically, after applying the photocurable adhesive composition which is not cured to the polarizing film, the protective film may be bonded to the adhesive composition application surface, and then the adhesive composition may be cured to form an adhesive. a method of laminating a photocurable adhesive composition on a surface of the adhesive composition, applying a polarizing film to the adhesive composition coating surface, and then curing the adhesive composition to form an adhesive layer. a method of casting an unhardened photocurable adhesive composition between a polarizing film and a protective film, and holding a laminate of a polarizing film and a protective film with a roller or the like, and uniformly stretching the adhesive composition on one side After the connection, the adhesive composition is cured to form an adhesive layer or the like.

Further, an optical member in which an optical layer of the above-described polarizing plate and other display optical functions is laminated is provided to the liquid crystal display device of the present invention. The other optical layers at this time preferably include a phase difference plate. In the liquid crystal display device of the present invention, the optical member is disposed on one side or both sides of the liquid crystal cell to make.

In the photocurable adhesive composition of the present invention, when a resin film having a low moisture permeability selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin is used as a protective film, After that, the adhesion force can be quickly expressed. After a certain period of time, the final adhesion force is also good, and the endurance test does not cause problems such as poor appearance, and even the endurance of the damp heat resistance test is excellent. This adhesive composition is particularly useful when the protective film is composed of an acrylic resin. Further, since the adhesive composition of the present invention has an extremely low viscosity, it is easy to apply it thinly and adhere without defects. The polarizing plate obtained by laminating the polarizing film and the protective film via the adhesive composition not only cures the adhesive composition in a short-time step, but also obtains a bonding strength of a certain strength by illumination. It can be manufactured with good productivity. Further, an optical member in which the polarizing plate is combined with another optical layer can form a liquid crystal display device having excellent reliability.

[Formation of the Invention]

Hereinafter, the present invention will be described in detail. In the present invention, when a polarizing film and a protective film are used, a photocurable adhesive composition having a specific composition containing a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye is used. The film system includes a transparent resin film. By adhering to the photocurable adhesive composition in this way A light film and a protective film are used to obtain a polarizing plate. The polarizing plate can be laminated with an optical layer having other optical functions to form an optical member. Further, the optical member may be disposed on at least one side of the liquid crystal cell to form a liquid crystal display device. Hereinafter, the order of the photocurable adhesive composition, the polarizing plate, the method of producing the polarizing plate, the optical member, and the liquid crystal display device will be described.

[Photocurable adhesive composition]

In the present invention, in order to bond the polarizing film and the protective film, a photocurable adhesive composition having a specific composition is used. Hereinafter, only the photocurable adhesive composition may be referred to as a "photocurable adhesive" or a "composition". The photocurable adhesive of the present invention must contain the following five components (A), (B), (C), (D), and (E): (A) having at least two formulas (1) in the molecule. An epoxy compound of an alicyclic epoxy group; (B) a poly(meth)acrylate having a carbon number of 2 to 15; (C) a photocationic polymerization initiator; (D) (2) a propylene oxide compound shown; (E) a polymer having an alkyl (meth) acrylate as an essential constituent monomer unit.

In the present specification, the epoxy compound of the above (A) is also referred to as "(A) component" or "epoxy compound (A)"; and the poly(meth)acrylate of (B) is also referred to as "(B) "Component" or "poly(meth)acrylate (B)"; the photocationic polymerization initiator of (C) is also referred to as "(C) component" or "photocationic polymerization initiator (C)"; The propylene oxide compound of the above (D) is also referred to as "(D) component" or "propylene oxide compound (D)"; the (E) alkyl (meth) acrylate is an essential constituent monomer Unit aggregation Also known as "(E) ingredient."

The content of the components in the components (A) to (E) is 10 to 65 wt% of the component (A) and 10 to 55 wt% of the component (B), based on the entire composition. (C) The component is 0.5 to 10% by weight, the component (D) is 1 to 25% by weight, and the component (E) is 0.1 to 25% by weight.

The photocurable adhesive may optionally contain a propylene oxide compound represented by the following formula (3) as the component (F), and preferably has a content ratio of 1 to 30% by weight. A photoradical polymerization initiator may be contained as the component (G), and a leveling agent may be contained as the component (H).

In the present specification, the propylene oxide compound of the above (F) is also referred to as "(F) component" or "propylene oxide compound (F)"; and the photoradical polymerization initiator of (G) is also referred to as " (G) component or "photoradical polymerization initiator (G)"; the leveling agent of (H) is also referred to as "(H) component" or "leveling agent (H)".

<epoxy compound (A)>

In the photocurable adhesive of the present invention, the epoxy compound having the (A) component has at least two epoxy compounds having an alicyclic epoxy group represented by the following formula (1) in the molecule, and a general compound can be used. Various hardening epoxy compounds are known. Further, in the formula (1), the wave line portion indicates the bonding position with other structures.

Specific examples of the component (A) include 3,4-epoxycyclohexane. Methyl-3,4-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate, 3,4-epoxycyclohexylmethyl-3,4- a caprolactone modification of an epoxycyclohexane carboxylate, an esterified product of a polycarboxylic acid and 3,4-epoxycyclohexylmethanol or a caprolactone modification, and an alicyclic ring represented by the above formula (1) An epoxy group-based compound such as an epoxy group.

Further, the number of the alicyclic epoxy groups represented by the formula (1) of the component (A) is preferably from 2 to 10, more preferably from the viewpoint of excellent low viscosity, hardenability, adhesion and durability. 2~6, then 2 is better.

As the component (A), the epoxy compound represented by the following formula (4) is preferable because it is excellent in low viscosity, hardenability, adhesion and durability.

The epoxy compound of the component (A) may be used singly or in combination of two or more.

The content ratio of the epoxy compound of the component (A) is in the range of 10 to 65% by weight based on the entire composition. By setting it as this range, the subsequent adhesive force, final adhesive force, and durability of the illuminating light can be made good. Further, by setting the content ratio of the component (A) to a range of 10 to 50% by weight, the adhesion can be further improved.

<Poly(meth)acrylate (B)>

In the photocurable adhesive of the present invention, the poly(meth)acrylate which is the component (B) is a poly(meth)acrylate having a polyhydric alcohol having 2 to 15 carbon atoms.

The (meth) acrylate having a (meth) acrylonitrile group number of 1 in the molecule is less likely to have insufficient durability such as cold cycle resistance.

By using the component (B), the viscosity of the composition can be lowered, and it is excellent in adhesion to the polarizing film and durability. Here, as the component (B), a di(meth)acrylate having a diol having 5 to 10 carbon atoms is more preferable from the viewpoint of low viscosity, adhesion, and durability. Further, as the (meth) acrylate, the acrylate is preferred from the viewpoint of curability.

Specific examples of the component (B) include neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 3-methyl-1,5-pentanediol. Di(meth)acrylate, cyclohexanedimethylol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9- Decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butanediol di(meth)acrylate, diethylene glycol di(a) Acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tricyclodecane dimethylol di(methyl) Acrylate, trimethylolpropane tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, pentaerythritol tri- or tetra(meth)acrylate, dipentaerythritol Five or six (meth) acrylates and hydrogenated bisphenol A bis (meth) acrylates.

The component (B) may also have an ester skeleton or an isomeric cyanate skeleton. Specific examples of the compound having an ester skeleton include an esterification reaction product of neopentyl glycol with hydroxytrimethylacetic acid and (meth)acrylic acid, and the like, and examples of the compound having an isomeric cyanate skeleton. Examples of the di- or tris(meth)acrylate of the isomeric cyanuric acid alkylene oxide adduct can be mentioned.

Among these, the esterification reaction product of 1,6-hexanediol di(meth)acrylate and neopentyl glycol with hydroxytrimethylacetic acid and (meth)acrylic acid has low viscosity and adhesion. The viewpoint of excellent durability and low odor is particularly preferable.

The content ratio of the component (B) is in the range of 10 to 55% by weight based on the entire composition. By setting this ratio, the subsequent adhesion force, final adhesion force, and durability of the illumination can be made good. Further, by setting the content ratio of the component (B) to a range of 20 to 45% by weight, the adhesion can be further improved.

<Photocationic polymerization initiator (C)>

The photocurable adhesive of the present invention contains the epoxy compound (A), the propylene oxide compound (D), and the propylene oxide compound described later as a curing component, and any of these may be used. It is hardened by cationic polymerization, and thus a photocationic polymerization initiator is blended as the component (C). The photocationic polymerization initiator generates a cationic species or a Lewis acid by irradiating an active energy ray such as visible light, ultraviolet light, X-ray or electron beam, and starts the polymerization of an epoxy group or an oxetane group. .

By blending the photocationic polymerization initiator as the component (C), it is hardenable at room temperature, and the necessity of considering the heat resistance of the polarizing film or the stress generated by the expansion or contraction is reduced, and the film can be favorably adhered. Further, since the photocationic polymerization initiator is photocatalytically irradiated by the active energy ray, it is also stable in storage stability or workability even when it is blended with the epoxy compound (A) and the propylene oxide compound (D). excellent. Examples of the compound which generates a cationic species or a Lewis acid by irradiation of an active energy ray include a sulfonium salt such as an aromatic diazonium salt, an aromatic sulfonium salt or an aromatic sulfonium salt. , iron-arene complexes, and the like.

Examples of the aromatic diazonium salt include the following compounds: benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

Examples of the aromatic onium salt include the following compounds: diphenylphosphonium tetrakis(pentafluorophenyl)borate, diphenylphosphonium hexafluorophosphate, diphenylphosphonium hexafluoroantimonate, and di(4-anthracene). Phenyl) quinone hexafluorophosphate.

Examples of the aromatic onium salt include the following compounds: triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, 4,4'- Bis(diphenyldihydrothio)diphenyl sulfide dihexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenyldihydrothiodiphenyl sulfide dihexafluoroantimony Acid salt, 4,4'-bis[bis(β-hydroxyethoxy)phenyldihydrothio]diphenyl sulfide dihexafluorophosphate, 7-[bis(p-tolyl)dihydrothio] 2-isopropyl thioxanthone hexafluoroantimonate, 7-[bis(p-tolyl)dihydrothio]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4- Phenylcarbonyl-4'-diphenyldihydrothio-diphenyl sulfide hexafluorophosphate Salt, 4-(p-tert-butylphenylcarbonyl)-4'-diphenyldihydrothio-diphenyl sulfide hexafluoroantimonate, 4-(p-tert-butylphenylcarbonyl)-4 '-Di(p-tolyl)dihydrothio-diphenyl sulfide tetrakis(pentafluorophenyl)borate.

Examples of the iron-aromatic complex include the following compounds: xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene. - cyclopentadienyl iron (II)-tris(trifluoromethanesulfonyl) methanide or the like.

These photocationic polymerization initiators may be used alone or in combination of two or more. Among these, in particular, the aromatic onium salt has an ultraviolet absorbing property even in a wavelength range of 300 nm or more, and therefore, a cured product having excellent curability and good mechanical strength or adhesion strength can be provided, and can be preferably used.

(C) component can be easily obtained as a commercial item, for example, "KAYARAD PCI-220", "KAYARAD PCI-620" (the above is manufactured by Nippon Kayaku Co., Ltd.), "UVI-6992", respectively, by the trade name. (made by Dow Chemical Co., Ltd.), "ADEKA OPTOMER SP-150", "ADEKA OPTOMER SP-160" (above, ADEKA Co., Ltd.), "CI-5102", "CIT-1370", "CIT-1682", “CIP-1866S”, “CIP-2048S”, “CIP-2064S” (above is Japanese Soda (share) system), “DPI-101”, “DPI-102”, “DPI-103”, “DPI-105” ", MPI-103", "MPI-105", "BBI-101", "BBI-102", "BBI-103", "BBI-105", "TPS-101", "TPS-102", "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102", "DTS-103" (above Midori Chemical Co., Ltd., "PI-2074" (manufactured by Rhodia Co., Ltd.), "IRGACURE 250", "IRGACURE PAG103", "IRGACURE PAG108", "IRGACURE PAG121", and "IRGACURE PAG203" (all manufactured by BASF Corporation) "CPI-100P", "CPI-101A", "CPI-210S", "CPI-110P" (the above is a San-Apro system). In particular, the "CPI-100P" and "CPI-110P" manufactured by San-Apro Co., Ltd. are particularly excellent in terms of hardenability and adhesion.

The content ratio of the component (C) is in the range of 0.5 to 10% by weight based on the entire composition. If the ratio is less than 0.5% by weight, the hardening of the adhesive becomes insufficient, and the mechanical strength or the subsequent strength decreases. On the other hand, if the ratio exceeds 10% by weight, the ionic substance in the cured product increases. On the other hand, there is a case where the hygroscopic property of the cured product becomes high and the durability can be lowered. In addition, the content ratio of the component (C) is preferably from 1 to 5% by weight, and by setting it as such a range, optical properties such as transparency and durability can be further improved.

<propylene oxide compound (D)>

In the photocurable adhesive of the present invention, a propylene oxide compound represented by the following formula (2) is blended as the component (D). By containing the (D) component, it is possible to enhance the speed of the adhesion after illumination. Moreover, the final adhesion force when the relative humidity of the coating environment is about 45% is improved. Further, in the relative humidity of the coating environment which may be changed, by containing the component (D), the adhesion can be exhibited even if the relative humidity of the coating environment is slightly changed.

The content ratio of the component (D) is preferably 1 to 25% by weight, preferably 1 to 18% by weight based on the entire composition. By containing the component (D) in a ratio of 1 to 25% by weight, the final adhesion force when the adhesion force after the illuminating is exhibited and the relative humidity with the coating environment is about 45% can be improved. Moreover, by preferably containing 18% by weight or less, even if the relative humidity of the coating environment is about 65%, the final adhesion is not deteriorated, and the relative humidity of the coating environment is raised to about 45%. The final adhesion force and the adhesion force under the two humidity conditions show the speed. The content of the component (D) is more preferably from 1 to 12% by weight.

<A polymer (E) having a (meth)acrylic acid alkyl ester as an essential constituent monomer unit>

In the photocurable adhesive of the present invention, by containing the component (E), the heat resistance test can be completed and the subsequent adhesive force is good. Further, in the present invention, the "polymer of (meth)acrylic acid alkyl ester is an essential constituent monomer unit" and the "polymer having at least a constituent monomer unit derived from an alkyl (meth)acrylate) Synonymous.

As the component (E), various polymers can be used as long as the (meth)acrylic acid alkyl ester is a polymer which is an essential constituent monomer unit. The component (E) is preferably a polymer containing 50 mol% or more of an alkyl (meth)acrylate as a constituent monomer unit, and more preferably a polymer containing 80 mol% or more.

Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate. Base) butyl acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylate 2 -ethylhexyl ester, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-decyl (meth)acrylate And isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, and n-tetradecyl (meth)acrylate.

Among these compounds, an alkyl (meth)acrylate having an alkyl group having 1 to 10 carbon atoms is preferred, and an alkyl (meth)acrylate having a lower alkyl group having 1 to 4 carbon atoms is more preferred.

The (E) component may be a copolymer of an ethylenically unsaturated monomer (hereinafter referred to as "another monomer") copolymerizable with a (meth) acrylate in addition to an alkyl (meth)acrylate. .

Specific examples of the other monomer include a carboxyl group-containing monomer such as (meth)acrylic acid; a sulfonic acid group-containing monomer such as acrylamide 2-methylpropanesulfonic acid or styrenesulfonic acid; and a phosphate group-containing monomer; a cyano group-containing monomer such as (meth)acrylonitrile or a vinyl ester; an aromatic vinyl compound such as styrene or α-methylstyrene; an acid anhydride group-containing monomer; hydroxyethyl (meth)acrylate; a hydroxyl group-containing monomer such as hydroxyethyl acrylate or hydroxybutyl (meth) acrylate such as hydroxyalkyl (meth) acrylate; decylamine such as acrylamide, dimethyl acrylamide or diethyl acrylamide Base monomer; amine group-containing monomer; quinone imine group-containing monomer; epoxy group-containing (meth)acrylic acid propyl acrylate; (meth) acrylonitrile group Porphyrin; and vinyl ether and the like.

As the component (E), various polymers can be used from the above polymer.

For the purpose of improving the adhesion and the solubility of the composition, a copolymer of an alkyl (meth)acrylate and an acid group-containing monomer is preferred.

Examples of the acid group-containing monomer include a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, an acid anhydride group-containing monomer, and a phosphoric acid group-containing monomer, and a carboxyl group-containing monomer is preferable.

The copolymer is preferably a copolymer having an acid value of 20 mgKOH/g or less, more preferably 15 mgKOH/g or less, for the reason that the storage stability of the composition is good.

The molecular weight of the component (E) is preferably from 1,000 to 500,000, more preferably from 1,000 to 200,000, based on the weight average molecular weight (hereinafter referred to as "Mw").

In the present invention, Mw means that the molecular weight measured by gel permeation chromatography (hereinafter also referred to as "GPC") is converted into polystyrene.

As the component (E), various polymers may be used from the above polymer, and it is preferred to use an alkyl (meth)acrylate having an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit, and a weight average molecular weight. It is a polymer of 1,000 to 500,000.

As a more preferable example of the polymer, for example, the following two polymers are exemplified:

‧ (E1) component: a polymer containing 60% by weight or more of methyl methacrylate as a constituent monomer unit and having a Mw of 1,000 to 200,000

‧ (E2) component: a polymer containing 60% by weight or more of an alkyl acrylate having an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit and having a Mw of 1,000 to 200,000.

The component (E1) is a polymer containing 60% by weight or more of methyl methacrylate as a constituent monomer unit and having a Mw of 1,000 to 200,000, which is preferable for the reason that the adhesion to the acrylic resin is excellent.

The component (E1) may be a copolymer with an acid group-containing monomer, and examples of the acid group-containing monomer include the same monomers as described above, and a carboxyl group-containing monomer is preferred.

The copolymer is preferably a copolymer having an acid value of 20 mgKOH/g or less, more preferably 15 mgKOH/g or less, for the same reason as described above.

The component (E1) is commercially available, and, for example, Dianal BR-80 manufactured by Mitsubishi Rayon Co., Ltd. (containing 60% by weight or more of methyl methacrylate as a constituent monomer unit, Mw 95,000, and an acid value of 0 mgKOH/g) PMMA-based polymer), with BR-83 (containing 60% by weight or more of methyl methacrylate as a constituent monomer unit, Mw 40,000, an acid value of 2 mgKOH/g of PMMA-based polymer) and the same BR-87 (including 60% by weight or more of methyl methacrylate is used as a constituent monomer unit, Mw 25,000, a PMMA-based polymer having an acid value of 10.5 mgKOH/g, and the like.

The (E1) component may be a high-temperature polymerization described later, and is preferably a high-temperature continuous polymerization.

The component (E2) is an alkyl acrylate containing 60% by weight or more of an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit, and Mw is 1,000 to 200,000, which is for protection of a polarizing film or an acrylic resin. The reason why the adhesion of the film is excellent is preferable.

Examples of the alkyl acrylate having an alkyl group having 1 to 10 carbon atoms include the same compounds as described above.

The (E2) component may be an alkyl acrylate containing 60% by weight or more of an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit, and may be copolymerized with an alkyl methacrylate or other monomer. Things.

The component (E2) may be an alkyl acrylate having an alkyl group having 1 to 10 carbon atoms, a block copolymer with an alkyl methacrylate or another monomer (hereinafter referred to as "(E2-1) component"). ].

Preferred examples of the monomer in the component (E2-1) include a block polymer having a polyacrylate block unit and a polymethacrylate block unit, and a polyacrylate block unit and A block polymer or the like of a block unit of a polymer of another monomer.

Among these, block polymers having polyacrylate block units and polymethacrylate block units, or even blocks containing polybutyl acrylate and polymethyl methacrylate as block units are used. Polymers are preferred.

The component (E2-1) can be produced by polymerization using a conventional method, and examples thereof include a radical polymerization method, a living anionic polymerization method, and a living radical polymerization method. Moreover, examples of the form of polymerization include a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method.

The component (E2-1) is commercially available, and KURARITY (LA1114, LA2140e, LA2330, LA2250) manufactured by Kuraray Co., Ltd. may be mentioned.

The component (E2) is a polymer having a Mw of 1,000 to 200,000, preferably a polymer having a Mw of 1,000 to 100,000, more preferably 1,000 to 20,000. This is because the polymer having the Mw is low in viscosity, the resulting composition is also low in viscosity and easy to apply; or even if there is a composition The limitation of low viscosity can still increase the number of blends, and as a result, the reason for the adhesion can be improved.

If the low molecular weight polymer is to be produced by a usual polymerization method, it is generally necessary to add a chain transfer agent or a polymerization initiator. When a polymer using a chain transfer agent in a large amount is used, the cationic hardenability or the bonding force of the composition is liable to lower; if a polymer using a polymerization initiator in a large amount is used, the storage stability of the composition becomes easy. decline.

Therefore, it is preferred to use a polymer prepared by high-temperature polymerization which does not require a large amount of a chain transfer agent or a polymerization initiator, and which contains 60% by weight or more of an alkyl acrylate having an alkyl group having 1 to 10 carbon atoms as A polymer which constitutes a monomer unit and has a Mw of 1,000 to 20,000 [hereinafter referred to as "(E2-2) component").

Further, in the present invention, Mw means that the molecular weight measured by GPC is converted into polystyrene.

The temperature for high-temperature polymerization is preferably 160 to 350 ° C, more preferably 180 to 300 ° C.

Among the high-temperature polymerizations, continuous polymerization at a high temperature is not only excellent in productivity, but also has a composition distribution in a copolymer product, and has an advantage of excellent compatibility.

The high-temperature continuous polymerization can be carried out by a known method (for example, JP-A-57-502171, JP-A-59-6207, JP-A-60-215007, and the like).

Specifically, a reactor that can be pressurized by a solvent is used, and after setting to a predetermined temperature under pressure, a reactor containing a monomer or a polymerization solvent according to a demand is supplied at a constant supply rate. Aggregation start A monomer mixture of the agent, and a method of extracting a reaction liquid in an amount corresponding to the supply amount of the monomer mixture.

The glass transition temperature of the component (E2-2) is preferably 20 ° C or lower, more preferably -90 to 0 ° C.

Further, in the present invention, the glass transition temperature means a value measured by a differential scanning calorimeter (DSC) at a temperature elevation rate of 2 ° C /min.

The component (E) of the present invention may be a cationically polymerizable functional group such as a radical polymerizable functional group such as a (meth)acrylinyl group or an epoxy group or an oxetanyl group. Examples of the method of introducing such a functional group include a method of introducing a terminal at the end of living anionic polymerization or living radical polymerization, a method of adding a compound having a polymerizable functional group to a functional group in a polymer, and the like. Further, in the case of introducing a cationically polymerizable functional group such as an epoxy group or an oxetanyl group, a (meth) acrylate having such a functional group may be copolymerized.

The component (E) may be used alone or in combination of two or more.

As a preferred combination of the component (E), it is preferred to use the (E1) component and the (E2) component in combination with the other types of substrates, and it is more preferable to use the (E1) component in combination with (E2-). 2) Ingredients.

The ratio of the combination of the (E1) component and the (E2) component is preferably from 1/9 to 7/3.

The content ratio of the component (E) is required to be 0.1 to 25% by weight, preferably 1 to 20% by weight, based on the entire composition. By containing the component (E) in a ratio of 0.1 to 25% by weight, the endurance of the damp heat resistance test can be made good.

<propylene oxide compound (F)>

In the photocurable adhesive of the present invention, a propylene oxide compound represented by the following formula (3) may be blended as the component (F). By containing the (F) component, it is possible to further enhance the adhesion force or the final adhesion force after the illumination.

The content ratio of the component (F) is preferably from 1 to 30% by weight. By setting this range, it is possible to further enhance the adhesion force or the final adhesion force after the illumination. The content ratio of the component (F) is more preferably from 1 to 20% by weight.

<Photoradical polymerization initiator (G)>

The radical curable component such as the component (B) contained in the photocurable adhesive of the present invention can be cured by radicals generated by photodecomposition of the component (C), and in order to reduce the amount of irradiation. In order to obtain a sufficient reaction rate, it is preferred to incorporate a photoradical polymerization initiator as the component (G). The blending ratio of the component (G) is preferably 10% by weight or less, and more preferably 0.1 to 3% by weight based on the entire composition. When the blending amount is 10% by weight or more, the deterioration of durability is not preferable.

Specific examples of the component (G) include, for example, the following compounds: 4'-phenoxy-2,2-dichloroacetophenone, 4'-tertiary butyl-2,2-dichloroacetophenone 2,2-dimethoxy-2-phenylacetophenone, 2-methyl-1-(4-methylthiophenyl)-2- Phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, α,α-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-( 4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 1 -[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one and 2-benzyl-2-dimethylamino-1-(4- An acetophenone photopolymerization initiator of phenyl phenyl)butan-1-one; a benzoin ether photopolymerization initiator such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; Benzophenone, methyl ortho-benzoylbenzoate, 4-phenylbenzophenone, 4-benzylidene-4'-methyldiphenyl sulfide and 2,4,6-trimethyl a benzophenone photopolymerization initiator of benzophenone; such as 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, and 1-chloro a thioxanthone photopolymerization initiator of -4-propoxythioxanthone; such as 2,4,6-trimethylbenzhydryldiphenylphosphine oxide, bis(2,6-dimethoxy Benzophosphonium oxide of bis-(2,4,6-trimethylbenzylidene)phenylphosphine oxide Photopolymerization initiator; such as 1,2-octanedione, 1-[4-(phenylthiophenyl)]-, 2-(O-benzylidenehydrazide) oxime ester photopolymerization initiator ; cerebral palsy and so on.

The component (G) can be used singly or in combination of two or more kinds depending on the desired properties.

When the photoradical polymerization initiator of the component (G) is blended, the content thereof is preferably 10% by weight or less, and more preferably 0.1 to 3% by weight based on the entire composition. When the content ratio of the photoradical polymerization initiator (G) is in the above range, sufficient strength can be obtained and the curability is excellent.

As the component (G), it is preferred that the mercaptophosphine is oxidized from the viewpoint of excellent adhesion. Compounds.

<Leveling agent (H)>

In the photocurable adhesive of the present invention, for the purpose of obtaining a coated surface having excellent smoothness, a leveling agent containing the component (H) is preferred.

Examples of the component (H) include a ruthenium-based leveling agent and a fluorine-based leveling agent, and various commercially available leveling agents can be used. Among these, a (meth)acrylonitrile-based oxime-based leveling agent is particularly preferred from the viewpoint of the end of the heat-resistant test and the subsequent adhesion.

The content ratio of the component (H) is preferably 0.01 to 0.5% by weight based on the entire composition. When the addition ratio is in the above range, the effect of adding the leveling agent can be sufficiently obtained, and the adhesion is excellent.

<Other hardening ingredients>

The photocurable adhesive of the present invention may contain other cationic hardening components or radical curable components in addition to the above components (A) to (H).

Examples of the cationically curable component other than the component (A), the component (D) and the component (F) include various epoxy compounds, propylene oxide compounds and vinyl ether compounds.

Specific examples of the epoxy compound other than the component (A) include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of brominated bisphenol A. , phenol novolak type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, hydroquinone diglycidyl ether, resorcinol diepoxypropyl ether, p-nonanoic acid bicyclo Oxypropyl propyl ester, diglycidyl citrate, addition reaction of terminal carboxylic acid polybutadiene with bisphenol A type epoxy resin, dicyclopentadiene dioxide, limonene dioxide, 4- Ethylene cyclohexene dioxide, 1,6-hexanediol diepoxypropyl ether, trimethylolpropane triepoxypropyl ether, pentaerythritol tetraepoxypropyl ether, polybutanediol Diepoxypropyl ether, hydrogenated bisphenol A diglycidyl ether, epoxidized vegetable oil, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 2-(3,4-epoxy Cyclohexyl)ethyltriethoxydecane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, polybutanediol bicyclic ring at both terminal carboxyl groups Oxypropyl propyl ether, internal epoxide of polytetramethylene glycol, a part of the double bond of styrene-butadiene copolymer, epoxidized compound [for example, "Epofriend" by DAICEL Chemical Industry Co., Ltd.], and ethylene-butyl A compound in which a part of the isoprene unit of the block copolymer of the olefin copolymer and the polyisoprene is epoxidized (for example, "L-207" manufactured by KRATON Co., Ltd.) or the like.

Specific examples of the propylene oxide compound other than the component (D) and the component (F) include an alkoxyalkyl group such as 3-ethyl-3-(2-ethylhexyloxymethyl) propylene oxide. Monofunctional propylene oxide, aromatic group-containing monofunctional propylene oxide such as 3-ethyl-3-phenoxymethyl propylene oxide, 1,4-bis[(3-ethyl propylene oxide) 3-yl)methoxymethyl]benzene, 1,4-bis[(3-ethylepoxypropan-3-yl)methoxy]benzene, 1,3-bis[(3-ethylcyclo) Oxypropan-3-yl)methoxy]benzene, 1,2-bis[(3-ethylepoxypropan-3-yl)methoxy]benzene, 4,4'-bis[(3-ethyl) Propylene oxide-3-yl)methoxy]biphenyl, 2,2'-bis[(3-ethylepoxypropan-3-yl)methoxy]biphenyl, 3,3',5,5 '-Tetramethyl-4,4'-bis[(3-ethylepoxypropan-3-yl)methoxy]biphenyl, 2,7-bis[(3-ethylepoxypropane-3- Methoxy]naphthalene, bis[4-{(3-ethyl propylene oxide-3-yl)methoxy}phenyl]methane, bis[2-{(3-ethyl propylene oxide-3) -yl)methoxy}phenyl]methane, 2,2-bis[4-{(3-ethylepoxypropan-3-yl)methoxy}phenyl]propane, phenolic phenol-formaldehyde resin Etherification modification by 3-chloromethyl-3-ethyl propylene oxide, 3(4), 8 (9)-bis[(3-ethylepoxypropan-3-yl)methoxymethyl]-tricyclo[5.2.1.0 ^2,6 ]decane, 2,3-bis[(3-ethyl) Propylene oxide-3-yl)methoxymethyl]norbornane, 1,1,1-tris[(3-ethylepoxypropan-3-yl)methoxymethyl]propane, 1-butyl Oxy-2,2-bis[(3-ethylepoxypropan-3-yl)methoxymethyl]butane, 1,2-bis[{2-(3-ethyl propylene oxide-3) -yl)methoxy}ethylthio]ethane, bis[{4-(3-ethyl propylene oxide-3-yl)methylthio}phenyl] sulfide, 1,6-bis[(3) -ethyl propylene oxide-3-yl)methoxy]-2,2,3,3,4,4,5,5-octafluorohexane, 3-[(3-ethyl propylene oxide-3 -yl)methoxy]propyltrimethoxydecane, 3-[(3-ethylepoxypropan-3-yl)methoxy]propyltriethoxydecane, 3-[(3-ethyl Hydrolyzed condensate of propylene oxide-3-yl)methoxy]propyltrialkoxydecane, tetrakis[(3-ethylepoxypropan-3-yl)methyl]decanoate, 3-ethyl A condensation reaction product of propylene oxide-3-ylmethanol and a decane tetraol polycondensate.

Specific examples of the vinyl ether compound include cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and triethylene glycol. Vinyl ether, cyclohexanedimethanol divinyl ether, and the like.

The content ratio of the cationically curable component other than the component (A), the component (D), and the component (F) is preferably less than 20% by weight, more preferably less than 10% by weight, based on the entire composition. It is less than 5% by weight.

Examples of the radical curable component other than the component (B) include various compounds, and examples thereof include (meth)acrylates, (meth)acrylamides, and maleimide. Methyl)acrylic acid, maleic acid, isaconic acid, (meth)acrolein, (meth)acrylonitrile Porphyrin, N-vinyl-2-pyrrolidone, allyl isocyanurate, divinyl adipate, ethylene trimethoxydecane, and the like.

Specific examples of the (meth) acrylate having one (meth) acryl fluorenyl group in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, (methyl) ) isooctyl acrylate, lauryl (meth) acrylate, stearyl methacrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (methyl) 4-hydroxybutyl acrylate, cyclohexyl (meth) acrylate, isodecyl (meth) acrylate, 1,4-cyclohexane dimethylol mono (meth) acrylate, (meth) acrylate Cyclopentyl ester, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, benzyl (meth)acrylate, phenol alkylene oxide adduct (methyl) (Meth) acrylate, p-isopropylphenol alkylene oxide adduct (meth) acrylate, o-phenol alkylene oxide adduct (meth) acrylate, nonylphenol alkylene oxide adduct (methyl) Acrylate, 2-methoxyethyl (meth)acrylate, (A Ethylene oxide ethoxy acrylate 2-ethylhexanol alkylene oxide adduct (meth) acrylate, pentanediol mono (meth) acrylate, hexane diol mono (meth) acrylate Monoester (meth) acrylate of ester, diethylene glycol, mono (meth) acrylate of triethylene glycol, mono (meth) acrylate of tetraethylene glycol, mono (methyl) of polyethylene glycol Acrylate, mono (meth) acrylate of dipropylene glycol, mono (meth) acrylate of tripropylene glycol, mono (meth) acrylate of polypropylene glycol, 2-hydroxy-3-phenoxypropyl (a) Acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, (meth) acrylate tetrahydrofuran ester, caprolactone modified (meth) acrylate tetrahydrofuran ester, (2-ethyl- 2-methyl-1,3-di 4-yl)methyl(meth)acrylate, (2-isobutyl-2-methyl-1,3-di 4-yl)methyl(meth)acrylate, (1,4-dioxaspiro[4,5]indol-2-yl)methyl(meth)acrylate, (meth)acrylic acid epoxy Propyl ester, 3,4-epoxycyclohexylmethyl (meth) acrylate, (3-ethyl propylene oxide-3-yl) methyl (meth) acrylate, 2-(methyl) isocyanate ) propylene oxime ethyl ester, allyl (meth) acrylate, N-(methyl) propylene oxiranyl hexahydro quinone imine, N-(methyl) propylene oxy oxyethyl tetrahydro fluorene Amine, 2-(methyl)propene oxime ethyl hexahydrophthalate, 2-(methyl) propylene oxime ethyl succinate, ω-carboxy-polycaprolactone mono(meth) acrylate, phosphoric acid 2 -(Methyl) propylene oxime ethyl ester, 3-(methyl) propylene oxypropyl trimethoxy decane, 3-(methyl) propylene oxypropyl dimethoxy methyl decane, 3- (A Base) propylene oxypropyl triethoxy decane, and the like.

Further, specific examples of the (meth) acrylates (hereinafter referred to as "polyfunctional (meth) acrylates)" other than the component (B) having two or more (meth) acrylonitrile groups in the molecule are exemplified. Polyethylene glycol di(meth)acrylate (excluding polyols having 15 or less carbon atoms), polypropylene glycol di(meth)acrylate (excluding polyols having 15 or less carbon atoms), and bisphenol A alkylene oxide addition The (meth) acrylate, the urethane (meth) acrylate, the (meth) acrylate of the polyester polyol having a carbon number of 16 or more, and the epoxy (meth) acrylate. The polyester (meth) acrylate having three or more (meth) acrylonitrile groups may, for example, be a dendrimer type (meth) acrylate.

The blending ratio of the polyfunctional (meth) acrylate is preferably 2 to 20% by weight in the composition.

Specific examples of the (meth) acrylamide are exemplified (A Acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N -(3-N,N-dimethylaminopropyl)(meth)acrylamide, methylenebis(meth)acrylamide, ethyl bis(methyl)propenamide, N,N - Diallyl (meth) acrylamide or the like.

Specific examples of the maleimide group include N-methylbutyleneimine, N-hydroxyethyl maleimide, and N-hydroxyethylmethoxide. a urethane-reacting reaction of decylamine, N-hydroxyethylmethyl maleimide and isophorone diisocyanate.

The content ratio of the radical curable component other than the component (B) is preferably less than 20% by weight based on the entire composition.

<Other ingredients that are not hardenable>

Further, in the photocurable adhesive of the present invention, other components having no curability can be optionally blended insofar as the effects of the present invention are not impaired, and specific examples thereof include a photosensitizer and a thermal cationic polymerization initiator. A polyol compound, water, or the like.

Specific examples of the photosensitizer include benzophenone, methyl ortho-benzoylbenzoate, 2-isopropylthioxanthone, and 9,10-dibutoxyfluorene. Among these, there are also compounds which are photoradical polymerization initiators of the above (G) component, but the term "photosensitizer" as used herein means sensitivity as a photocationic polymerization initiator for the component (C). The agent acts. These may be used alone or in combination of two or more.

The content ratio of the photosensitizer is preferably less than 3% by weight based on the entire composition.

Specific examples of the thermal cationic polymerization initiator include a benzyl sulfonium salt, a tetrahydrothiophene sulfonium salt, a thiofuranium salt, a benzylammonium salt, a pyridinium salt, a hydrazine salt, a carboxylic acid ester, a sulfonate, an amine quinone, or the like. Such a starting agent can be easily obtained as a commercially available product, and examples thereof include "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (the above are manufactured by ADEKA Co., Ltd.) and "CI-2639", both of which are represented by the trade names. "CI-2624" (the above is manufactured by Japan Soda Co., Ltd.), "SUNAID SI-60L", "SUNAID SI-80L", and "SUNAID SI-100L" (the above is manufactured by Sanshin Chemical Industry Co., Ltd.).

The content of the thermal cationic polymerization initiator is preferably less than 3% by weight based on the entire composition.

Specific examples of the polyol compound include ethylene glycol, propylene glycol, a polyether polyol compound, a polyester polyol compound, a polycaprolactone polyol compound, and a polycarbonate polyol compound.

The blending ratio of the polyol compound is preferably less than 10% by weight based on the entire composition.

The viscosity of the photocurable adhesive of the present invention is preferably a coating surface which is excellent in smoothness even when the film is applied, in order to obtain a coating property which can be used in the production step of the polarizing plate. The viscosity at 25 ° C is preferably 150 mPa ‧ s Hereinafter, it is more preferably 100 mPa‧s or less. It is preferably 50mPa‧s or less.

In the photocurable adhesive of the present invention, a small amount of water may be added in order to improve the adhesion to the polarizing film having a high degree of dryness. In this case, the amount of water added is preferably less than 3% by weight, and more preferably less than 1% by weight based on the entire composition.

In addition to these, as long as the effect of the invention is not impaired, it can be blended Mixed ion trapping agent, antioxidant, light stabilizer, chain transfer agent, tackifier, thermoplastic resin, metal oxide fine particles, antifoaming agent, coloring matter, organic solvent, and the like.

[Polarizer]

The photocurable adhesive agent described above is for applying a protective film to a polarizing film, and the polarizing film comprises a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye, and the protective film is thus It is bonded to the polarizing film to form a polarizing plate. In other words, in the polarizing plate of the present invention, the protective film is bonded to a polarizing film comprising a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye. The protective film may be attached only to one side of the polarizing film, or may be attached to both sides of the polarizing film. When the protective film is bonded to both surfaces of the polarizing film, each of the protective films may be one containing the same kind of resin, or may be a resin containing different types.

<polarized film>

The polyvinyl alcohol-based resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may, for example, be a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate of a homopolymer of vinyl acetate. Examples of the other monomer copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is preferably from 85 to 100 mol%, more preferably from 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, an aldehyde-modified polyvinyl formal or a polyvinyl acetal may be used. The degree of polymerization of the polyvinyl alcohol-based resin is preferably from 1,000 to 10,000, more preferably from 1,500 to 10,000.

The polarizing plate is produced by a step of uniaxially stretching the polyvinyl alcohol-based resin film, and a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye; a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed with an aqueous solution of boric acid; a step of washing with water after treatment with an aqueous solution of boric acid; and a step of uniaxially stretching the adsorption of a dichroic dye by performing such steps The step of bonding a vinyl alcohol resin film to a protective film.

The uniaxial stretching may be carried out before the dyeing by the dichroic dye, or simultaneously with the dyeing by the dichroic dye, or after the dyeing by the dichroic dye. When uniaxially stretching is carried out by dyeing with a dichroic dye, the uniaxial stretching can be carried out before the boric acid treatment or in the boric acid treatment. It is of course also possible to carry out a uniaxial extension in several stages of this. The uniaxial extension can be uniaxially stretched between rolls having different peripheral speeds, or can be uniaxially extended by a heat roll. Further, it may be a dry stretching which is extended in the atmosphere, or may be a wet stretching which is extended in a state of being swollen by a solvent. The stretching ratio is preferably about 4 to 8 times.

When the polyvinyl alcohol-based resin film is dyed with a dichroic dye, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic dye can be specifically used.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is preferably used. The content of iodine in the aqueous solution is preferably about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is preferably per 100 parts by weight. The water content is about 0.5 to 10 parts by weight. The temperature of the aqueous solution is preferably about 20 to 40 ° C, and the immersion time of the aqueous solution is preferably about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye and dyed is preferably used. The content of the dichroic dye in the aqueous solution is preferably from about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight per 100 parts by weight of water. The aqueous solution may also contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is preferably about 20 to 80 ° C, and the immersion time of the aqueous solution is preferably about 30 to 300 seconds.

The boric acid treatment by dyeing the dichroic dye is carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The content of boric acid in the aqueous boric acid solution is preferably about 2 to 15 parts by weight, more preferably about 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the aqueous boric acid solution is preferably from 2 to 20 parts by weight, more preferably from 5 to 15 parts by weight, per 100 parts by weight of water. Immersion time for boric acid aqueous solution It is preferably about 100 to 1,200 seconds, more preferably about 150 to 600 seconds, and preferably about 200 to 400 seconds. The temperature of the aqueous boric acid solution is preferably 50 ° C or higher, more preferably 50 to 85 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is subjected to a water washing treatment. The water washing treatment is suitably carried out, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. After washing with water, drying treatment was carried out to obtain a polarizing film. The temperature of the water in the water washing treatment is preferably about 5 to 40 ° C, and the immersion time is preferably about 2 to 120 seconds. Afterwards The drying treatment is preferably carried out using a hot air dryer or a far infrared heater. The drying temperature is preferably from 40 to 100 °C. The treatment time in the drying treatment is preferably about 120 to 600 seconds.

Thus, a polarizing film comprising a polyvinyl alcohol-based resin film which adsorbs iodine or a dichroic dye having a dichroic dye is obtained.

<Protective film>

Next, the polarizing film is bonded to the one surface or both surfaces of the protective film by using the photocurable adhesive described above. The cellulose triacetate film widely used as a protective film for a polarizing film has a moisture permeability of about 400 g/m ² /24 hr. However, in the present invention, a protective film which is bonded to at least one side of the polarizing film is used. A resin exhibiting a moisture permeability lower than that of the cellulose triacetate, that is, a polyester resin, a polycarbonate resin, an acrylic resin or an amorphous polyolefin resin.

The type of the polyester resin used for the protective film is not particularly limited, but polyethylene terephthalate is particularly preferable in terms of mechanical properties, solvent resistance, scratch resistance, cost, and the like. The polyethylene terephthalate refers to a resin composed of 80 mol% or more of a repeating unit of ethylene phthalate, and may contain a constituent unit derived from another copolymerized component. Examples of the other copolymerization component include isodecanoic acid, p-β-hydroxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl ester, 4,4′-dicarboxybenzophenone, and bis ( 4-carboxyphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfonate isophthalic acid and 1,4-dicarboxycyclohexane dicarboxylic acid components; such as propylene glycol, butanediol, new A diol component of pentanediol, diethylene glycol, cyclohexanediol, an ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polybutanediol. These dicarboxylic acid components or diols The components may be used in combination of two or more types as needed. Further, a hydroxycarboxylic acid such as p-hydroxybenzoic acid may be used in combination with the above dicarboxylic acid component or diol component. As the other copolymerization component, a small amount of a dicarboxylic acid component and/or a diol component having a guanamine bond, a urethane bond, an ether bond, or a carbonate bond may be used.

As a method for producing the polyester resin, a direct reaction of citric acid with ethylene glycol (further depending on other dicarboxylic acids and/or other diols as required), that is, a so-called direct polymerization method; The methyl ester is subjected to a transesterification reaction with ethylene glycol (further, other dimethyl dicarboxylates and/or other diols as required), that is, any method such as a so-called transesterification reaction. Further, the polyester resin may contain a known additive as needed. Examples of the additives which may be contained include a lubricant, an anti-caking agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, and an impact resistance improver. However, since it is required to have transparency as a protective film laminated on the polarizing film, it is preferable to control the amount of the additive to a minimum.

By forming the raw material resin into a film shape and performing uniaxial stretching or biaxial stretching treatment, a protective film containing an extended polyester resin can be produced. By performing the stretching treatment, a film having high mechanical strength can be obtained. The method for producing the stretched polyester resin film is not particularly limited, and an unaligned film in which the raw material resin is melted and extruded into a sheet shape is used, and the tenter is transversely formed at a temperature higher than the glass transition temperature. The method of performing heat setting treatment after extension.

When a polyester resin is used as the protective film, in order to obtain good adhesion, it is preferred to carry out corona treatment before applying the adhesive or to use a polyester resin film having a surface easily treated layer.

The polycarbonate resin used for the protective film is a polyester formed of carbonic acid and a diol or bisphenol. Among them, an aromatic polycarbonate having a diphenyl alkane in a molecular chain is preferably used because of its excellent heat resistance, weather resistance, and acid resistance. As such a polycarbonate, it can be exemplified by, for example, 2,2-bis(4-hydroxyphenyl)propane (alias bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-double Polycarbonate of (4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, or 1,1-bis(4-hydroxyphenyl)ethane .

As a method of producing the polycarbonate resin film, any one of a casting film forming method and a melt extrusion method can be employed. As an example of a specific production method, a polycarbonate resin solution is prepared by dissolving a polycarbonate resin in an appropriate organic solvent, and casting it on a metal support to form a web. After the metal material is peeled off from the metal support, the peeled web is dried by hot air to obtain a film.

The acrylic resin to be used for the protective film is not particularly limited, but is generally a polymer in which methacrylate is a main monomer, and a copolymer in which a small amount of other comonomer components are copolymerized is preferable. The methacrylate which is a main component of the acrylic resin is preferably an alkyl methacrylate, and particularly preferably methyl methacrylate. Further, as the comonomer component, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate or the like is generally used. Further, an aromatic vinyl compound such as styrene, a cyanoethylene compound such as acrylonitrile, or the like is sometimes used as a comonomer component.

As a method of producing the acrylic resin, any method such as general bulk polymerization, suspension polymerization, or emulsion polymerization can be employed. Among these, it is particularly preferable to use a bulk polymerization in which no water-soluble component is present in the polymerization system. also It is preferred to use a chain transfer agent in the polymerization in order to obtain a suitable glass transition temperature or to obtain a viscosity which exhibits a suitable formability to the film. The amount of the chain transfer agent may be appropriately determined depending on the type and composition of the monomer. Further, the acrylic resin may also contain well-known additives as needed. As a known additive, a slip agent, an anti-caking agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, an impact resistance improver, a surfactant, etc. are mentioned, for example. However, since it is required to have transparency as a protective film laminated on the polarizing film, it is preferable to control the amount of the additive to a minimum.

As a method for producing the acrylic resin film, any one of a melt extrusion method, a T-die method, an inflation method, and the like, a melt extrusion method, a calender method, or the like can be employed. Further, a method of forming a film by melt-extruding a raw material resin from, for example, a T-shaped mold, and bringing at least one side of the obtained film material into contact with a roll or a strip is preferable from the viewpoint of obtaining a film having a good surface property.

The acrylic resin may contain acrylic rubber particles which are impact modifiers, from the viewpoints of film forming properties of the film or impact resistance of the film. The term "acrylic rubber particles" as used herein refers to particles having an elastomeric polymer mainly composed of an acrylate as an essential component, and examples thereof include a single layer structure including substantially only the elastic polymer. A multi-layer structure of one layer. Examples of the elastic polymer include a crosslinked elastic copolymer in which an alkyl acrylate is used as a main component and another ethylene monomer and a crosslinkable monomer copolymerizable therewith are copolymerized. Examples of the alkyl acrylate which is a main component of the elastic polymer include those having an alkyl group such as methyl acrylate, ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate having a carbon number of about 1 to 8. Excellent use with carbon number 4 The above alkyl acrylate. Examples of the other ethylene monomer copolymerizable with the alkyl acrylate include a compound having one polymerizable carbon-carbon double bond in the molecule, and more specifically, a methacrylate such as methyl methacrylate. For example, an aromatic vinyl compound such as styrene, a cyanoethylene compound such as acrylonitrile, or the like. Further, examples of the crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, for example, ethylene glycol di(meth)acrylate and butylene glycol. A (meth) acrylate of a di(meth) acrylate polyol, an alkenyl (meth) acrylate such as (meth) acrylate, divinyl benzene or the like.

Further, a laminate of a film containing an acrylic resin containing no rubber particles and a film containing an acrylic resin containing rubber particles can also be used as a protective film.

When an acrylic resin is used as the protective film, if the composition of the present invention is used, good adhesion can be obtained without corona treatment, but the coating property of the adhesive is good or the adhesion is further improved. Corona treatment can be performed prior to application of the adhesive.

The amorphous polyolefin-based resin used for the protective film usually has a polymerized unit derived from a polycyclic cyclic olefin such as a norbornene or a derivative thereof, such as a dicyclic octahydronaphthalene, such as a ring-opening polymer. When a double bond remains, it is preferred to hydrogenate the thermoplastic resin there. The amorphous polyolefin-based resin may be a copolymer of a cyclic olefin and a chain olefin, or may be a polar group. Among them, a thermoplastic saturated decene-based resin is representative. Examples of commercially available amorphous polyolefin-based resins include "ARTON" of JSR (shares), "ZEONEX" and "ZEONOR" of Japan's ZEON (shares), and "APO" of Mitsui Chemicals Co., Ltd. "APEL" and so on. Amorphous polyolefin When the resin is formed into a film to form a film, a known method such as a solvent casting method or a melt extrusion method is preferably used for the film formation.

When an amorphous polyolefin-based resin is used as the protective film, in order to obtain good adhesion, it is preferred to carry out corona treatment before applying the adhesive.

In the polarizing plate used for the visual recognition side of the liquid crystal display device, the anti-glare property can be imparted to the protective film disposed on the opposite side of the liquid crystal cell. In this case, an anti-glare layer having surface irregularities is generally provided on the surface on the side of the visibility side of the protective film, that is, on the surface opposite to the surface to be bonded to the polarizing film. The antiglare layer is generally provided with an embossing method for imparting irregularities to an active energy ray-curable resin, or by hardening and mixing a particle having a refractive index different therefrom in an active energy ray-curable resin. The method of imparting unevenness is formed. Further, when the protective film is made of an acrylic resin, it is also effective to form a protective film by laminating a film of a light-diffusing layer and a transparent layer, wherein the light-diffusing layer is blended in an acrylic resin to be an adhesive to have a refractive index different therefrom. The particles are at a rate, and the transparent layer comprises an acrylic resin that is not blended with the particles. In this case, a laminated film including two layers of the light-diffusing layer and the transparent layer may be bonded to the polarizing film with the light-diffusing layer side; and both surfaces of the light-diffusing layer may be sandwiched by the transparent layer. The laminated film of the layer structure is in the form of a transparent layer attached to the polarizing film or the like. In addition, even when an acrylic resin laminated film including such a light-diffusing layer is provided as an anti-glare property as a protective film, the surface on the side of the visibility side, that is, the surface opposite to the surface to be bonded to the polarizing film Further, it is also effective to provide the antiglare layer as described above to further improve the antiglare property.

As described above, in particular, when an acrylic resin film is used as a protective film, the epoxy resin-free epoxy resin monomer shown in the prior patent document 6 (JP-A-2004-245925) is not necessarily sufficient. Further, the composition of the present invention can impart a good adhesion when the acrylic resin film is used as a protective film. Therefore, the present invention is particularly useful when an acrylic resin film is used as a protective film.

In the present invention, a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin selected from the above-described ones are bonded to at least one of the polarizing films via a photocurable adhesive described above. A protective film of a resin transparent resin film. When the protective film is bonded to one surface of the polarizing film, for example, an adhesive layer or the like for bonding to another member such as a liquid crystal cell may be directly provided on the other surface of the polarizing film.

On the other hand, when the protective film is bonded to both surfaces of the polarizing film, the protective films may be of the same type or different types. Specifically, for example, a form in which a polyester resin film is bonded as a protective film on both surfaces of a polarizing film; a form in which a polycarbonate resin is bonded as a protective film on both surfaces of the polarizing film; and both sides of the polarizing film are used a form in which an acrylic resin is bonded as a protective film; an amorphous polyolefin-based resin is bonded as a protective film on both surfaces of the polarizing film; and a single side of the polarizing film is selected from a polyester resin and a polycarbonate. Any of a transparent resin film of a resin, an acrylic resin, and an amorphous polyolefin resin is bonded as a protective film, and is selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous film on the other side of the polarizing film. Any of the transparent polyolefin-based resins and the transparent resin film different from the one-sided protective film as a protective film State and so on. Furthermore, it is also possible to apply a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin as a protective film on one side of the polarizing film, and On the other side of the polarizing film, a transparent resin film different from any one of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin is bonded as a protective film. When the protective film is bonded to both surfaces of the polarizing film, the two protective films can be laminated one by one in a stepwise manner, and the both faces can be bonded in one step.

When one of the protective films is bonded to both surfaces of the polarizing film, when one of them is a resin film different from the polyester resin, the polycarbonate resin, the acrylic resin, and the amorphous polyolefin resin, the other resin is used. A cellulose resin is mentioned as a suitable example. Further, a protective film comprising a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin bonded to one surface of the polarizing film is subjected to the photocurability described above in accordance with the present invention. Next, the protective film attached to the other surface of the polarizing film may be followed by another adhesive. For example, when a protective film containing a resin film having a high moisture permeability such as a cellulose resin film is provided on one surface of the polarizing film, the bonding surface of the resin film having a high moisture permeability may be polyethylene. An adhesive other than an epoxy type such as an alcohol-based adhesive. However, the photocurable adhesive of the present invention can impart a high adhesion to the cellulose-based resin film exemplified herein. Therefore, it is advantageous to use the same adhesive on both surfaces of the polarizing film because of simple operation.

A part or a complete esterified product of cellulose-based resin-based cellulose as a protective film of one of them may be used, and for example, cellulose may be mentioned. Acetate, propionate, butyrate, mixed esters thereof, and the like. Specific examples thereof include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, and the like. In the case of a commercially available product including a film of such a cellulose ester resin, there are "FUJITAC TD80", "FUJITAC TD80UF", and "FUJITAC TD80UZ" and "Konica Minolta Opto" ("K") manufactured by Fuji FILM Co., Ltd. KC8UX2M" and "KC8UY" and so on. Further, a cellulose resin film to which an optical compensation function is imparted can also be used. The optical compensation film may, for example, be a film containing a compound having a phase difference adjustment function in a cellulose resin, a compound having a phase difference adjustment function applied to a surface of a cellulose resin film, or a cellulose resin film. The resulting film or the like is extended toward a single axis or a biaxial direction. In the case of a commercially available cellulose-based optical compensation film, there are "wide viewing angle film WV BZ 438" and "wide viewing angle film WV EA" manufactured by Fuji FILM Co., Ltd., and "KC4FR-1" manufactured by Konica Minolta Opto Co., Ltd. And "KC4HR-1" and so on.

As another resin different from the polyester resin, the polycarbonate resin, the acrylic resin, and the amorphous polyolefin resin, an example of a transparent resin having a low moisture permeability of one of the protective films can be used, and examples thereof include polyfluorene. Resin, alicyclic polyimine resin, and the like.

The protective film may be subjected to an easy subsequent treatment such as saponification treatment, corona treatment, primer treatment, anchor coating treatment, or the like on the bonding surface before bonding to the polarizing film. Further, the surface of the protective film opposite to the bonding surface to the polarizing film may be provided with various treatment layers such as a hard coat layer, an antireflection layer, and an antiglare layer. The thickness of the protective film is preferably in the range of about 5 to 200 μm, more preferably 10 to 120 μm, and still more preferably 10 to 85 μm.

[Method of Manufacturing Polarizing Plate]

The polarizing plate of the present invention can be produced by a method comprising the steps of: the polarizing film previously described, and a transparent resin comprising a resin selected from the group consisting of polyester resin, polycarbonate resin, acrylic resin, and amorphous polyolefin resin. At least one of the bonding surfaces of the protective film of the film, an adhesive application step of applying the photocurable adhesive described above; a bonding step of bonding the polarizing film and the protective film via the obtained adhesive layer; In the adhesive layer, the photocurable adhesive is cured in a state in which the polarizing film and the protective film are bonded together.

<Binder coating step>

In the adhesive application step, the photocurable adhesive described above is applied to at least one of the bonding surfaces of the polarizing film and the protective film. When the photocurable adhesive is directly applied to the surface of the polarizing film or the protective film, the coating method is not particularly limited. For example, various coating methods such as blade coating, wire bar coating, die coating, comma coating, and gravure coating can be used. Further, a method in which the photocurable adhesive described above is cast between the polarizing film and the protective film, and then uniformly pressed by a roller or the like may be used.

The ambient temperature of the subsequent coating step is preferably 15 to 30 ° C, and more preferably 20 to 25 ° C. Further, the relative humidity of the coating environment is preferably 80% or less, more preferably 70% or less, still more preferably 30 to 70%, and particularly preferably 40 to 60%. By adjusting the ambient temperature and humidity of the adhesive application step to the above range, the adhesion force display speed or the final adhesion force can be stably made stable.

Moreover, outside the ambient temperature, the temperature of the adhesive at the time of coating is Heating or heating may be performed for the purpose of improving the coating property or the adhesion improving force described later by low viscosity. The heating or heating temperature at this time is preferably 80 ° C or lower, more preferably 20 to 60 ° C. However, after applying the film to the bonding step, the adhesive coating film is exposed to an environment of 15 to 30 ° C and a humidity of 80% or less, and the viewpoint of the adhesion force display speed or the final adhesion force is good. good.

<Fitting step>

After the photocurable adhesive is applied in this manner, a bonding step is provided. In the bonding step, for example, in the case where the photo-curable adhesive is applied to the surface of the polarizing film in the previous coating step, the protective film is laminated thereon; and in the previous coating step, the photo-curing property is applied to the surface of the protective film. In the case of the subsequent agent, the polarizing film is laminated thereon. Further, in the case where the photocurable adhesive is cast between the polarizing film and the protective film, the polarizing film and the protective film are laminated in this state. In the case where the protective film is bonded to both surfaces of the polarizing film, and the photocurable adhesive of the present invention is used on both surfaces, the protective film is laminated on both surfaces of the polarizing film via a photocurable adhesive. Further, in general, in this state, from both sides (in the case where the protective film is superposed on one side of the polarizing film, the polarizing film side and the protective film side are formed; and when the protective film is laminated on both sides of the polarizing film, The protective film side on both sides thereof is sandwiched and pressurized by a roller or the like. Here, the material of the roller may be metal or rubber. The rollers disposed on both sides can be the same material or different materials.

<hardening step>

As described above, the polarizing film and the protective film are bonded to each other via the uncured photocurable adhesive, and the curing step is followed. In this hardening step, the photocurable adhesive is irradiated with an active energy ray. The adhesive layer containing an epoxy compound, a (meth) acrylate, a propylene oxide compound, etc. is hardened, and a polarizing film and a protective film are followed. In the case where the protective film is bonded to one side of the polarizing film, the active energy ray can be irradiated from either the polarizing film side or the protective film side. In the case where the protective film is bonded to both surfaces of the polarizing film, the active energy rays are irradiated from either of the protective film sides in a state in which the protective film is bonded to each other via the photocurable adhesive on both surfaces of the polarizing film. It is advantageous for the hardenable adhesive to harden at the same time. However, when any of the protective films is doped with an ultraviolet absorber (for example, when a cellulose resin film in which an ultraviolet absorber is blended is one of the protective films), and the active energy ray is ultraviolet rays, it is generally Ultraviolet rays are irradiated from the side of the protective film which is not blended with the ultraviolet absorber.

As the active energy ray, visible light, ultraviolet light, X-ray, electron beam or the like can be used. However, since the treatment is easy and the curing speed is sufficient, ultraviolet rays are generally preferably used. The light source of the active energy ray is not particularly limited, and may be used for, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light, a microwave-excited mercury lamp, a metal halide lamp, or an LED having a light-emitting distribution with a wavelength of 400 nm or less. Lights, etc.

The light intensity of the photocurable adhesive can be determined according to the composition of each purpose, and is not particularly limited, but it is preferred that the irradiation intensity of the active wavelength region of the polymerization initiator is UV-B (280). The wavelength of ~320 nm medium wavelength region indicates that the system is 1 to 3,000 mW/cm ² . When the irradiation intensity is in the above range, the reaction time is appropriate, and yellowing of the photocurable adhesive or deterioration of the polarizing film due to heat emitted from the lamp and heat generated during polymerization of the photocurable adhesive can be suppressed.

The illuminating time of the photocurable adhesive can be controlled for each hardened composition, and is not particularly limited. However, it is preferable that the integrated light amount expressed by the product of the irradiation intensity and the irradiation time is expressed by UV-B. 10~5,000mJ/cm ² . When the integrated light amount is in the above range, the active species derived from the polymerization initiator are sufficiently generated, and the adhesive layer is sufficiently cured, and the irradiation time is short and the productivity is excellent.

When the active energy ray is irradiated to cure the photocurable adhesive, it is preferred that the function of the polarizing plate such as the degree of polarization of the polarizing film, the transmittance, and the transparency of the hue and the protective film are not lowered. Hardening.

In the polarizing plate thus obtained, the thickness of the adhesive layer is preferably 50 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less, and still more preferably 5 μm or less.

As a preferred method for further enhancing the adhesion between the adhesive of the present invention and the protective film, it is also possible to apply the polarizing film and the protective film after using the adhesive to irradiate the active energy ray without impairing the optical characteristics of the polarizing film. A heating step is added to the inside. The heating condition at this time is preferably set within a range in which shrinkage of the polarizing film or deterioration of optical characteristics does not occur. Suitable heating conditions may vary depending on the molecular weight of the acrylic resin, etc., and may be, for example, 1 to 10 seconds at 60 ° C and 5 to 30 seconds at 40 ° C. After heating, until the temperature of the adhesive is cooled to 40 ° C or less during the irradiation of the active energy ray, the force-improving effect is not impaired.

Further, as another preferred method for improving the adhesion between the adhesive of the present invention and the protective film, it is possible to illuminate the active energy even after the polarizing film and the protective film are stretched at a temperature of 20 to 25 ° C even without heating. line The length of the manufacturing line is increased by about 60 seconds after the adhesive is brought into contact with the acrylic resin.

[Optical member]

When a polarizing plate is used, it is also possible to form an optical member in which an optical layer other than the optical function of the polarizing function is laminated on one side. An optical layer laminated on the polarizing plate for the purpose of forming an optical member, for example, a reflective layer, a semi-transmissive reflective layer, a light diffusing layer, a phase difference plate, a concentrating plate, a brightness enhancement film, or the like for forming a liquid crystal display device. Various things. The reflective layer, the semi-transmissive reflective layer, and the light-diffusing layer are used to form an optical member including a reflective or semi-transmissive type, a diffusion type, and the like.

The reflective polarizing plate is a liquid crystal display device of a type that is used to reflect incident light from the visual recognition side. Since the light source such as a backlight can be omitted, the liquid crystal display device can be made thinner. Further, the semi-transmissive polarizing plate is a liquid crystal display device of a type that is displayed as a reflective display in a bright place and a light source such as a backlight in a dark place. As the optical member of the reflective polarizing plate, for example, a foil containing a metal such as aluminum or a vapor deposited film may be attached to the protective film on the polarizing film to form a reflective layer. The optical member as the semi-transmissive polarizing plate can be formed by subjecting the above-mentioned reflective layer to a half mirror or a reflecting plate which exhibits light transmittance by containing a pearl pigment or the like, followed by a polarizing plate. On the other hand, as the optical member of the diffusing type polarizing plate, for example, a method of performing a mat treatment on a protective film on a polarizing plate, a method of applying a microparticle-containing resin, a method of subsequently including a microparticle-containing film, and the like can be employed. A fine uneven structure is formed on the surface.

Moreover, as an optical structure of a polarizing plate for reflection and diffusion The formation of the member can be performed by, for example, providing a reflective layer or the like reflecting the uneven structure on the fine uneven structure surface of the diffusion type polarizing plate. The reflective layer of the fine uneven structure has the advantages of being able to diffuse incident light by scattering reflection, preventing directivity or blindness, and suppressing unevenness of light and dark. Further, the resin layer or film containing fine particles also has the advantage that the incident light and the reflected light thereof are diffused while penetrating the particle-containing layer, and the unevenness of light and dark can be further suppressed. The reflective layer reflecting the fine uneven structure on the surface can be formed by directly attaching a metal to the surface of the fine uneven structure by a method such as vapor deposition or plating such as vacuum deposition, ion plating, or sputtering. As the fine particles to be blended for forming the surface fine uneven structure, for example, inorganic fine particles containing cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, or the like having an average particle diameter of 0.1 to 30 μm can be used. Organic fine particles such as a polymer which is or is not crosslinked.

On the other hand, the phase difference plate as the optical layer described above is used for the purpose of compensating for the phase difference caused by the liquid crystal cell. Examples thereof include a birefringent film including a stretched film of various plastics, a film in which a discotic liquid crystal or a nematic liquid crystal is fixed, and a liquid crystal layer formed on the film substrate. In this case, as the film substrate supporting the alignment liquid crystal layer, a cellulose-based film such as cellulose triacetate is preferably used.

Examples of the plastic forming the birefringent film include polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefin such as polypropylene, polyarylate, polyamine, and amorphous. A polyolefin resin or the like. The stretch film system can be treated in a suitable manner such as uniaxial or biaxial. Also, by being followed by a heat shrinkable film A birefringent film that has a contraction force and/or an extension force and controls the refractive index in the thickness direction of the film. Further, the phase difference plate can also control the optical characteristics such as the wide band, and two or more pieces can be used in combination.

The concentrating sheet is used for the purpose of controlling the optical path and the like, and can be formed as a ytterbium array sheet, a lens array sheet, or a dotted sheet.

The luminance-increasing film is used for the purpose of improving the luminance of a liquid crystal display device or the like, and examples thereof include a film in which a plurality of layers of refractive index have different anisotropy, and anisotropic reflection of reflectance. The linear polarizing separation sheet supports an alignment film of a cholesteric liquid crystal polymer or a circularly polarizing separator of the alignment liquid crystal layer on the film substrate.

The optical member may be a combination of a polarizing plate and one or more layers selected from the above-mentioned reflective layer to the semi-transmissive reflective layer, the light diffusing layer, the phase difference plate, the concentrating plate, the luminance lifting film, etc., depending on the purpose of use. The layer is formed into a laminate of 2 or more layers. In this case, two or more optical layers such as a light diffusion layer, a phase difference plate, a concentrating plate, or a brightness enhancement film may be disposed. Further, the arrangement of the respective optical layers is not particularly limited.

The various optical layers forming the optical member are integrated with the polarizing plate using an adhesive, and the adhesive used for this purpose is not particularly limited as long as the adhesive layer can be favorably formed. Adhesives (also referred to as "pressure-sensitive adhesives") are preferably used from the viewpoint of the convenience of the work or the prevention of the occurrence of optical strain. As the adhesive, an acrylic polymer or a fluorene-based polymer, a polyester, a polyurethane, a polyether or the like can be used as the base polymer. Among them, it is preferable to use an acrylic adhesive such as an optical adhesive, to maintain a moderate wettability or cohesive force, and to adhere to a substrate. It is excellent, and has weather resistance, heat resistance, etc., and does not cause peeling problems such as lifting or peeling under heating or humidification conditions. In the acrylic adhesive, an alkyl ester of (meth)acrylic acid having an alkyl group having a carbon number of 20 or less such as a methyl group or an ethyl group or a butyl group, and (meth)acrylic acid or (meth) group are contained. A functional group-containing acrylic monomer such as hydroxyethyl acrylate is polymerized to obtain an acrylic copolymer having a glass transition temperature of preferably 25° C. or lower, more preferably 0° C. or lower, and a weight average molecular weight of 100,000 or more. It is used as a base polymer.

The formation of the adhesive layer of the polarizing plate can be prepared into a liquid having a solid concentration of 10 to 40% by weight, for example, by dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate, and directly A method of forming an adhesive layer by applying it on a polarizing plate; forming an adhesive layer on the separator film in advance, transferring it to a polarizing plate to form an adhesive layer, or the like. The thickness of the adhesive layer is determined according to the adhesion force, etc., but the range of about 1 to 50 μm is appropriate.

Further, in the adhesive layer, a filler, a pigment or a coloring agent, an antioxidant, an ultraviolet absorber, or the like containing glass fibers, glass beads, resin beads, metal powder or other inorganic powder may be blended as needed. The ultraviolet absorber is a salicylate-based compound, a benzophenone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, or a nickel-salted salt-based compound.

[Liquid Crystal Display Device]

The optical member as described above can be disposed on one side or both sides of the liquid crystal cell to form a liquid crystal display device. Any of the liquid crystal cell systems used, The liquid crystal display device is formed using various liquid crystal cells such as an active matrix drive type represented by a thin film transistor type and a simple matrix drive type represented by a super twisted nematic type. The optical members disposed on both sides of the liquid crystal cell may be the same or different.

[Examples]

The present invention will be more specifically illustrated by the following examples and comparative examples, but the present invention is not limited by the examples. In the examples, the amount used or the % of the content is expressed as a weight basis unless otherwise specified. Further, the % moisture indicates the relative humidity at 23 °C. In addition, "parts" means "parts by weight" unless otherwise stated.

In the examples and comparative examples, the components used for the preparation of the photocurable adhesive composition are as follows. Hereinafter, it is represented by the compound name or its code (the trade name itself or a part thereof).

(A) component: epoxy compound

CEL-2021: an alicyclic epoxy compound represented by the above formula (4), "Celloxide 2021P" manufactured by DAICEL Chemical Industry Co., Ltd.

(B) component: poly(meth) acrylate compound

HDDA: 1,6-hexanediol diacrylate, "light acrylate 1,6HX-A" manufactured by Kyoeisha Chemical Co., Ltd.

(B)' component: (meth) acrylate compound other than (B) component

M-7100: an acrylate mixture containing a trifunctional or higher polyester acrylate as a main component, and "ARONIX M-7100" manufactured by Toagosei Co., Ltd.

V#1000: Dendritic polyester acrylate, "VISCOAT #1000" manufactured by Osaka Organic Chemical Industry Co., Ltd.

(C) component: photocationic polymerization initiator

CPI-100P: a 50% propylene carbonate solution containing triarylsulfonium hexafluorophosphate as a main component and a "CPI-100P" manufactured by San-Apro Co., Ltd. The table shows the number of parts of the active ingredient.

CPI-110P: triarylsulfonium hexafluorophosphate (100% active ingredient), "CPI-110P" manufactured by San-Apro Co., Ltd. It is equivalent to the active ingredient in CPI-100P.

(D) component: propylene oxide compound represented by the above formula (2)

OXT-101: 3-ethyl-3-hydroxymethyl propylene oxide, "ARONE OXETANE OXT-101" manufactured by Toago Corporation.

(E) component: (meth)acrylic polymer

BR-80: a PMMA-based polymer containing 60% by weight or more of methyl methacrylate as a constituent monomer unit, Mw 95,000, an acid value of 0 mgKOH/g, and "Dianal BR-80" manufactured by Mitsubishi Rayon Co., Ltd.

BR-83: a PMMA-based polymer containing 60% by weight or more of methyl methacrylate as a constituent monomer unit, Mw 40,000, an acid value of 2 mgKOH/g, and "Dianal BR-83" manufactured by Mitsubishi Rayon Co., Ltd.

BR-87: a PMMA-based polymer containing 60% by weight or more of methyl methacrylate as a constituent monomer unit, Mw 25,000, an acid value of 10.5 mgKOH/g, and "Dianal BR-87" manufactured by Mitsubishi Rayon Co., Ltd.

LA2140: Mw 80,000, acid value 0 mgKOH/g. A block copolymer of methyl methacrylate and butyl acrylate, containing 60% by weight or more of butyl acrylate as a constituent monomer unit, and both ends of PMMA. Kuraray ("KURARITY LA2140e").

LA1114: Mw 80,000, acid value 0 mgKOH/g. Methacrylate A block copolymer of a methyl ester and butyl acrylate, containing 60% by weight or more of butyl acrylate as a constituent monomer unit, and a single-end PMMA. Kuraray ("KURARITY LA1114").

Polymer A: The polymer obtained in Production Example 1 described later.

(F) component: propylene oxide compound represented by the above formula (3)

OXT-221: 3-ethyl-3-[(3-ethyl propylene oxide-3-yl)methoxymethyl] propylene oxide, "ARONE OXETANE OXT-221" manufactured by Toagos Corporation.

(G) component: photoradical polymerization initiator

Irg-184: 1-hydroxy-cyclohexyl-phenyl-ketone, "IRGACURE 184" manufactured by BASF Corporation.

Irg-819: bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide, "IRGACURE 819" manufactured by BASF Corporation.

(H) component: leveling agent

BYK-UV3500: BYK-UV3500, a fluorene-based oxime-based leveling agent in the molecule of BYK.

SH-28: Dow CORNING TORAY (DOW CORNING TORAY SH 28 PAINT ADDITIVE) which does not have an acrylonitrile group in the molecule.

Other ingredients

OXT-212: 3-ethyl-3-(2-ethylhexyloxymethyl) propylene oxide, "ARONE OXETANE OXT-212" manufactured by Toagos Corporation.

PC: propylene carbonate (solvent brought in by the above CPI-100P)

[Manufacturing Example 1]

A pressurized stirred tank type with a capacity of 1,000 mL with a lubricating oil jacket The jacket temperature of the reactor was maintained at 181 °C. Next, while maintaining the pressure of the reactor constant, the butyl acrylate (45 parts), 2-ethylhexyl acrylate (45 parts), methyl methacrylate (10 parts), and the polymerization solvent were started. a monomer mixture of propanol (9 parts), methyl ethyl ketone (9 parts), bis(tri-butyl) peroxide (0.25 parts) as a polymerization initiator, at a certain supply rate (48 g/ Minute, residence time: 12 minutes) Continuously supplied to the reactor from the raw material tank, and the reaction liquid corresponding to the supply amount of the monomer mixture was continuously withdrawn from the outlet. It was confirmed that after the reaction was started immediately after the reaction temperature was temporarily lowered, the temperature rose due to the heat of polymerization, but the temperature of the oil jacket was controlled to maintain the internal temperature of the reactor at 183 to 185 °C. The time point after 36 minutes after the internal temperature of the reactor was stabilized was taken as the starting point of the reaction liquid, and as a result of continuing the reaction for 25 minutes, 1.2 kg of the monomer mixture was supplied and 1.2 kg of the reaction liquid was recovered. Thereafter, the reaction liquid is introduced into a thin film evaporator, and volatile components such as unreacted monomers are separated to remove volatile components such as unreacted monomers, thereby obtaining a polymer "polymer A". As a result of measuring GPC, the number average molecular weight (Mn) in terms of polystyrene was 2,500, the weight average molecular weight (Mw) was 7,500, and the viscosity at 25 ° C was 20,000 mPa·s.

[Modulation of photocurable adhesive composition]

Each component shown in Table 1 and Table 2 was blended in various ratios, and stirred and mixed by a conventional method to prepare a photocurable adhesive composition. Further, as described above, since "CPI-100P" which is a component (C) is used, a propylene carbonate solution containing 50% of an active ingredient is used, and in the table, the component (C) is separately shown from propylene carbonate. That is, the blending amount of "CPI-100P" in the table means the ratio of the active ingredient, and the blending amount of "CPI-100P" itself is the amount indicated by the column of the component (C) and the column of propylene carbonate. The sum of the quantities indicated.

The viscosity of the obtained composition at 25 ° C was measured by an E-type viscometer manufactured by Toki Sangyo Co., Ltd.

[Production of polarizing plate]

Here, the following two types of films are used as a protective film.

The decene-based resin film was stretched to a thickness of 70 μm, traded under the trade name “ZEONOR film”, and manufactured by Japan ZEON Co., Ltd. The film is subjected to a corona discharge treatment and then applied to the polarizing film.

Acrylic resin film: 80 μm thick, trade name "Technolloy S001", Sumitomo Chemical Co., Ltd. The film is also applied to the polarizing film after the corona discharge treatment.

On the corona discharge treated surface of the above-described extended decene-based resin film and the corona discharge treated surface of the acrylic resin film, the composition prepared by the above application was applied to a bar coater to a thickness of 3 μm. Next, three sheets of the film were simultaneously bonded to each other by sandwiching the polarizing film having iodine adsorbed on the polyvinyl alcohol. In this way, the polarizing film to which the protective film is bonded on both sides is formed by extending the surface of the terpene-based resin film by using an ultraviolet irradiation device (a high-pressure mercury lamp made of EYE GRAPHICS) equipped with a belt conveyor. The amount of light of 250 mJ/cm ² (UV-B) was irradiated with ultraviolet rays to harden the composition of the adhesive.

The experiment was carried out at 23 ° C and a relative humidity of 50%.

[assessment test]

For the polarizing plate after the ultraviolet irradiation, the adhesion force, the final adhesion force, the hot and cold cycle test, the damp heat resistance test, and the heat resistance after the damp heat resistance test were evaluated by the following methods, and the results were summarized in Tables 1 and 2.

<Continue force display speed>

Three minutes after the irradiation of the ultraviolet rays, the acrylic resin film and the polarizing film were peeled off by hand, and at this time, the stronger the force, the better the adhesion speed was evaluated. Then, the force is determined based on the following four levels based on the condition and force of the hand peeling.

◎: Material damage occurred in the acrylic resin film.

○: The material is not broken if it is slowly peeled off, but it is a strong adhesive force.

△: There is no strength at which material damage occurs, but it is not weak to the extent that it can be peeled off with a slight force.

×: A very weak degree can be peeled off with a slight force.

<Final adhesion/tool insertion test>

One day after the irradiation of the ultraviolet ray, the blade of the utility knife was obliquely inserted from above the acrylic resin film, and the situation and force at the time were determined according to the following four levels.

◎: The blade cannot be inserted, or has strength even when inserted, and the acrylic film is broken.

○: The blade is insertable but resistant, and the acrylic film is cut at the interface.

△: The blade can be inserted, but it is not weak enough to advance the blade with only a slight force at the interface.

×: The blade can be inserted and weakened to the extent that the blade advances with only a slight force at the interface.

<Cold and heat cycle test>

For the polarizing plate after 2 days or more after the irradiation of ultraviolet rays, it was repeatedly placed 300 times at -35 ° C for 60 minutes, and then placed at +70 ° C for 60 minutes. The thermal shock cycle test of the ring. The polarizing plate after the hot and cold cycle test was visually observed and judged according to the following three levels.

○: The appearance was not confirmed to be defective.

△: It was confirmed that the appearance was poor.

×: The appearance was poor.

<Damp heat resistance test>

The polarizing plate which had been irradiated with ultraviolet rays for 2 days or more was cut into a width of 1 cm and a length of 6 cm, and placed in a high-temperature and high-humidity environment of 60 ° C and a relative humidity of 90% for 500 hours. For the polarizing plate after the damp heat resistance test, peeling or discoloration was visually observed, and it was judged by the following three levels.

○: No peeling or discoloration was observed.

△: A slight peeling or discoloration was confirmed.

×: Peeling or discoloration was confirmed.

<End-end evaluation after moisture and heat resistance test>

After the end of the damp heat resistance test, the environment was quickly moved to 23 ° C and a relative humidity of 50%, and the adhesion of the polarizing plate was pulled to evaluate the adhesion after 5 minutes from the high temperature and high humidity environment. At this time, the acrylic resin was bent inside and the corners were bent by 5 mm by 90°, and then the hands were released, and it was evaluated whether or not peeling occurred 10 times or more, and the following three levels were determined.

○: No peeling was observed 10 times or more.

△: Peeling was observed on average between 3 and 9 times.

×: Peeling was observed twice or less.

<Acrylic resin bending adhesion force after moisture resistance test>

After the end of the damp heat test, quickly move to an environment of 23 ° C and a relative humidity of 50%, and make the acrylic resin face up and stick the polarizing plate to the glass. After the plate was taken out from a high-temperature and high-humidity environment for 5 minutes and 15 hours, the acrylic resin was peeled off at a tensile speed of 60 mm/min and 180°, and the adhesion was measured. The strength at this time and the breakage of the acrylic resin material were determined according to the following four levels.

◎: 6N/cm or more or cannot be peeled off

○: 3 N/cm or more or material destruction of acrylic resin during peeling

△: 0.1 N/cm or more and less than 3 N/cm

×: less than 0.1 N/cm

The unit of each numerical value in the blending composition of Tables 1 and 2 is % by weight.

First, the first embodiment to the ninth embodiment will be described.

The compositions of Examples 1 to 9 which are the composition of the adhesive of the present invention are not only the viscosity, the adhesion display speed, the final adhesion force, the hot and cold cycle test, the damp heat resistance test, and the heat and humidity test after 15 hours. Then, the force was excellent, and after the end of the moist heat resistance test, the adhesion force after taking out for 5 minutes was also good. Therefore, not only as the basicity of the adhesive for polarizing plates Excellent performance, and the reliability of transportation in high temperature and high humidity environment is also improved.

Among these, in the compositions of Examples 7 to 9, if the acrylic resin was bent and peeled off after the endurance test, the acrylic resin immediately broke and could not be peeled off. That is, the end of the heat and humidity resistance test is further enhanced.

Further, the composition of Example 9 using the polymer A had a viscosity at 25 ° C of 50 mPa ‧ s or less, and was excellent in coatability.

Next, Comparative Example 1 will be described.

The composition of Comparative Example 1 containing no (E) component was excellent in viscosity, adhesion display speed, final adhesion, cold cycle test, and damp heat resistance test, and the adhesion force after 15 hours after the end of the damp heat test was also Excellent, but the adhesion after 5 minutes after the end of the damp heat test was greatly reduced.

[Industrial availability]

The photocurable adhesive composition of the present invention has a low viscosity and is easily applied as a film, and the adhesion speed and final adhesion of the polarizing film and the protective film after illumination are excellent, and the adhesion resistance is excellent after the end of the moist heat test. Further, since the obtained polarizing plate is excellent in durability, it can be suitably used for the production of a polarizing plate.

Claims (17)

A photocurable adhesive composition for use in an adhesive composition of a polarizing film followed by a protective film, wherein the polarizing film comprises a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye, The protective film includes a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin, and the photocurable adhesive composition is characterized by containing: A) an epoxy compound having at least two alicyclic epoxy groups represented by the following formula (1) in the molecule; (B) a poly(meth)acrylate having a carbon number of 2 to 15 polyols; (C) a photocationic polymerization initiator; (D) a propylene oxide compound represented by the following formula (2); (E) A polymer having a (meth)acrylic acid alkyl ester as an essential constituent monomer unit, and the content ratio of the component (A) to (E) in the composition is (A) component: 10 to 65 wt% (B) Component: 10 to 55% by weight (C) Component: 0.5 to 10% by weight (D) Component: 1 to 25% by weight (E) Component: 0.1 to 25% by weight. The photocurable adhesive composition of claim 1, wherein the component (A) is an epoxy compound represented by the following formula (4): The photocurable adhesive composition according to claim 1, wherein the component (B) is a di(meth)acrylate having a carbon number of 5 to 10, but the repeating number of the alkylene oxide unit is 3. Except for the above polyether diol. The photocurable adhesive composition according to claim 1, wherein the content ratio of the component (A) and the component (B) is 10 to 50% by weight and 20 to 45% by weight, respectively, based on the composition. The photocurable adhesive composition of claim 1, wherein the component (E) comprises: an alkyl (meth)acrylate containing an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit, and a weight average molecular weight It is a polymer of 1,000 to 500,000. The photocurable adhesive composition according to claim 5, wherein the component (E) comprises: 60% by weight or more and 100% by weight or less of methyl methacrylate as a constituent monomer unit, and a weight average molecular weight of 1,000 to 200,000 Polymer. The photocurable adhesive composition according to claim 5, wherein the component (E) comprises: an alkyl acrylate containing 60% by weight or more and 100% by weight or less of an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit; And a polymer having a weight average molecular weight of 1,000 to 200,000. The photocurable adhesive composition according to claim 7, wherein the component (E) comprises a polymer obtained by high temperature polymerization, and the polymer contains 60% by weight or more and 100% by weight or less of a carbon number of 1 to 10 carbon atoms. Acrylate The base ester is a constituent monomer unit and has a weight average molecular weight of 1,000 to 20,000. The photocurable adhesive composition according to claim 1, wherein the propylene oxide compound represented by the following formula (3) is further contained in the composition in an amount of from 1 to 30% by weight as the component (F): The photocurable adhesive composition according to claim 1, wherein the (G) photoradical polymerization initiator is further contained in the composition in an amount of 0.1 to 10% by weight. The photocurable adhesive composition of claim 10, wherein the component (G) contains a mercaptophosphine oxide compound. The photocurable adhesive composition of claim 1, wherein the composition further contains 0.01 to 0.5% by weight of a (H) leveling agent. A polarizing plate comprising a polarizing film in which a protective film is bonded to a polarizing film via an adhesive, wherein the polarizing film comprises a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed and has a dichroic dye. The protective film system includes a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin, and the polarizing plate is characterized in that the adhesive is as claimed in claim 1 The photocurable adhesive composition of any one of 12 is formed. A method for producing a polarizing plate, which is a method for producing a polarizing plate by bonding a protective film to a polarizing film via an adhesive, wherein the polarizing film comprises a polyvinyl alcohol-based uniaxially stretched and adsorbed dichroic dye a resin film comprising a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin, the manufacturing method characterized by: an adhesive coating a step of applying a photocurable adhesive composition according to any one of claims 1 to 12 on at least one of a bonding surface of the polarizing film and the protective film; and a bonding step of separating the obtained adhesive The polarizing film and the protective film are bonded to the layer; and the curing step is performed by bonding the photocurable adhesive composition to a state in which the polarizing film and the protective film are bonded to each other via the adhesive layer. An optical member characterized by having another optical layer laminated on a polarizing plate as claimed in claim 13. The optical member of claim 15, wherein the other optical layers comprise phase difference plates. A liquid crystal display device characterized in that an optical member as claimed in claim 15 is disposed on one side or both sides of a liquid crystal cell.