KR20150075377A - Photocurable adhesive composition, polarizer and process for producing same, optical member, and liquid-crystal display device - Google Patents

Abstract

The present invention provides a photocurable adhesive and a polarizing plate having a polarizer laminated with a protection film by using the adhesive. The photocurable adhesive: has excellent curability even in an environment with high humidity; has proper adhesiveness proper to various forces after a certain period of time; does have problems after a durability test; has proper adhesiveness after a moisture and heat resistance test; and has low viscosity. The adhesiveness composition is used to attach the protection film, comprising a transparent resin film selected from certain four kinds, to the polarizer made of a polyvinyl alcohol-based resin film. The adhesiveness composition includes, at a certain ratio: (A) poly(meth) acrylate of polyol having 2-15 carbon atoms; (B) polyglycidyl ether of polyol having 2-10 carbon atoms; (C) a compound which has two or more oxetanyl groups and the molecular weight of 500 or smaller; (D) a polymer having an epoxy group; and a light cation polymerization initiator.

Description

TECHNICAL FIELD [0001] The present invention relates to a photo-curable adhesive composition, a polarizing plate and a process for producing the same, an optical member and a liquid crystal display device,

The present invention relates to a photo-curable adhesive composition used for bonding a polarizer and a protective film in a polarizing plate, a polarizing plate in which a protective film is applied to a polarizer using the adhesive composition, and a method for producing the polarizing plate. The present invention also relates to an optical member and a liquid crystal display device using this polarizing plate.

The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate is usually used by being mounted on a liquid crystal display device with a protective film laminated on both sides of the polarizer. It is also known that a protective film is formed only on one side of a polarizer, but in most cases, a layer having other optical function is combined not only as a simple protective film on the other side but also as a protective film. As a method for producing a polarizer, there is widely known a method in which a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic dye is subjected to boric acid treatment, followed by washing with water and drying.

Normally, the protective film is directly adhered to the polarizer after the above-described water washing and drying. This is because the polarizer after drying has a weak physical strength, and once it is excited, a problem such as tearing in the processing direction occurs. Therefore, after drying, the polarizer is generally applied directly to the water-based adhesive, and then the protective film is simultaneously adhered to both surfaces of the polarizer through the adhesive. Generally, a triacetylcellulose film having a thickness of 30 to 120 占 퐉 is used as a protective film.

A polyvinyl alcohol-based adhesive is often used to adhere a protective film made of a polarizer and a protective film, particularly a triacetylcellulose film. However, an attempt has been made to use a urethane-based adhesive instead. For example, Japanese Unexamined Patent Application Publication No. 7-120617 (Patent Document 1) discloses a method in which a urethane prepolymer is used as an adhesive, and a polarizer having a high water content is bonded to a cellulose acetate-based protective film, for example, a triacetyl cellulose film .

On the other hand, triacetyl cellulose has a high moisture permeability. Therefore, the polarizing plate in which this resin film is laminated as a protective film has problems such as deterioration under the conditions of, for example, a temperature of 70 DEG C and a relative humidity of 90%. Thus, a method for solving such a problem has been proposed by using a resin film having a lower moisture permeability than triacetylcellulose film as a protective film. For example, it has been known to use an amorphous polyolefin resin as a protective film. Specifically, it is described in JP-A-6-51117 (Patent Document 2) that a thermoplastic saturated norbornene resin sheet is laminated as a protective film on at least one surface of a polarizer.

When such a protective film having low moisture permeability is to be attached to a conventional device, a protective film is applied to a polyvinyl alcohol polarizer using an adhesive containing water as a main solvent, for example, a polyvinyl alcohol aqueous solution, In the so-called wet lamination, sufficient adhesive strength can not be obtained, or the appearance is poor. This is because the film having a low moisture permeability is generally hydrophobic compared with the triacetyl cellulose film, but the water as the solvent can not be sufficiently dried because of low moisture permeability.

Japanese Unexamined Patent Application Publication No. 2000-321432 (Patent Document 3) proposes to adhere a protective film made of a polyvinyl alcohol-based polarizer and a thermoplastic saturated norbornene-based resin with a polyurethane-based adhesive. However, the polyurethane-based adhesive has a problem that a long time is required for hardening, and the adhesive strength is not necessarily sufficient.

On the other hand, it is known that a protective film of a different kind is applied to both surfaces of a polarizer. For example, Japanese Patent Application Laid-Open No. 2002-174729 (Patent Document 4) discloses a polarizer comprising a polarizer made of a polyvinyl alcohol- It has been proposed to join a protective film made of an amorphous polyolefin resin and a protective film made of a resin different from the amorphous polyolefin resin, for example triacetyl cellulose, on the other side. Japanese Unexamined Patent Application Publication No. 2005-208456 (Patent Document 5) discloses a method in which a cycloolefin-based resin film is laminated on one side of a polarizing film made of a polyvinyl alcohol-based resin via a first adhesive of water-base containing a specific urethane resin, 1 adhesive agent, which is different from the first adhesive agent, for example, a polyvinyl alcohol-based resin, It has been proposed to laminate a set-acid-cellulose-based resin film.

In Patent Document 4, what is called an amorphous polyolefin-based resin and referred to as cycloolefin-based resin in Patent Document 5 is norbornene or a derivative thereof, a polycyclic olefin such as dimethano-octahydronaphthalene , And when a double bond such as a ring-opening polymer remains, it is preferably a hydrogenated thermoplastic resin.

Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 6) discloses an adhesive mainly comprising an epoxy resin not containing an aromatic ring. The adhesive is irradiated with active energy rays to perform cationic polymerization, A method of bonding a protective film has been proposed. The epoxy-based adhesive disclosed here is particularly effective for bonding various transparent resin films including an amorphous polyolefin-based resin and a cellulose-based resin to a polarizer, but particularly when an acrylic resin is used as a protective film, It was revealed that it did not.

Therefore, the present inventors have found that when a resin film having low moisture permeability selected from an acrylic resin, a polyester resin, a polycarbonate resin and an amorphous polyolefin resin is used as a protective film for a polarizer, Curable adhesives were developed. As a result, it has been found that a composition containing a glycidyl ether type epoxy resin having an aromatic ring and an oxetane compound gives a good adhesive force, and particularly a composition containing 5 to 25% by weight of a (meth) acrylate monomer having an alicyclic skeleton And exhibits high adhesion and durability (Patent Document 7). However, in this adhesive, the production process itself ends with a short-time process called light irradiation, but there is a problem that sufficient adhesive force can not be exhibited unless a certain period of time has elapsed after the film is wound. For this reason, there has been a problem that it is difficult to handle the film after light irradiation in the production process.

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

The adhesive composition was a photo-curable adhesive for a polarizing plate that not only had adhesive strength and durability but also productivity.

Japanese Patent Application Laid-Open No. 7-120617 Japanese Patent Application Laid-Open No. 6-51117 Japanese Patent Application Laid-Open No. 2000-321432 Japanese Patent Application Laid-Open No. 2002-174729 Japanese Patent Application Laid-Open No. 2005-208456 Japanese Patent Application Laid-Open No. 2004-245925 Japanese Laid-Open Patent Publication No. 2010-209126 Japanese Laid-Open Patent Publication No. 2012-140610

However, in the case of the adhesive disclosed in Patent Document 8, when a protective film made of an acrylic resin and a polarizer are adhered to each other, an anti-moisture heat test is conducted under a high temperature and high humidity environment (for example, 60 ° C. and 90% Lt; RTI ID = 0.0 > 23 C < / RTI > 50%).

When the protective film made of an acrylic resin is peeled off when the film is left in a normal environment for 15 hours, the deterioration of the adhesive force is restored as the protective film breaks the material. Even after the end of the moisture resistance test, peeling of the protective film does not occur depending on the force (shear direction or vertical force) applied in the form of the product to which the polarizing plate is attached to the glass. However, it is desired to improve the peel strength immediately after the end of the moisture resistance heat test, assuming that the worst case is that the polarizer is exposed to a high temperature and high humidity environment during transportation and immediately enters the processing step.

In the case of bonding a protective film made of an acrylic resin and a polarizer, a good adhesion is exhibited in a peeling test in which a polarizer is stuck to a plate such as glass to bend an acrylic resin film, or a T-peeling test in which both films are bent, In the peeling test in which the polarizer is bent by attaching the glass plate to a plate of glass or the like, the adhesive force is remarkably reduced. For this reason, if a strong force for bending the polarizer is applied to the end portion in the processing step of the polarizing plate or the like, peeling may occur. For the purpose of preventing such a problem, there has been a demand for an adhesive exhibiting a good adhesive force even in the peeling test in which an acrylic resin film is fixed to a plate and a polarizer is bent.

It is an object of the present invention to provide a resin composition which is excellent in curability even when a resin film having low moisture permeability selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is used as a protective film, The present invention also provides a photocurable adhesive which has good adhesive strength, does not cause problems such as poor appearance after an endurance test, exhibits good adhesion after completion of the anti-wet heat test, and has a low viscosity before curing. Another object of the present invention is to provide an adhesive exhibiting excellent adhesion even when a polarizer is attached to a protective film made of an acrylic resin and a protective film made of an acrylic resin is attached to the plate to bend the polarizer.

Here, the present invention focuses on providing an adhesive that solves the above problems even when the humidity at the time of applying the adhesive is high.

It is still another object of the present invention to provide an optical member capable of forming a liquid crystal display device having excellent reliability by using a polarizing plate using the adhesive and to apply it to a liquid crystal display device.

That is, according to the present invention, an adhesive for bonding a protective film made of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin to a polarizer made of a polyvinyl alcohol- As a composition,

(A) a poly (meth) acrylate of a polyol having 2 to 15 carbon atoms,

(B) a polyglycidyl ether of a polyol having 2 to 10 carbon atoms,

(C) a compound having a molecular weight of 500 or less and having at least two oxetanyl groups in one molecule,

(D2) a hydrocarbon group having 1 to 10 carbon atoms and a methacryloyl group having 1 to 10 carbon atoms, and (d2) a compound having an epoxy group and an ethylenically unsaturated group (hereinafter referred to as " (Hereinafter referred to as " monomer (d2) "), and optionally (d3) a compound having one ethylenic unsaturated group other than the monomers (d1) (Hereinafter referred to as " Tg ") of 20 ° C or more and a weight average molecular weight (hereinafter referred to as " Mw ") of 1,000 to 5,000, 30,000 polymer,

(E) a photocathode polymerization initiator,

The content ratio of the components (A) to (E)

Component (A): 5 to 50 wt%

Component (B): 5 to 45 wt%

Component (C): 5 to 45 wt%

Component (D): 1 to 25 wt%

(E): 0.5 to 10 wt%

And a photocurable adhesive composition.

As the component (A), a di (meth) acrylate of a diol having 2 to 10 carbon atoms is preferable. As the (meth) acrylate, acrylate is more preferable.

As the component (B), a diglycidyl ether of a diol having 2 to 10 carbon atoms (except polyether diol having 3 or more repeating number of alkylene oxide units is excluded) is preferable.

As the component (C), an oxetane compound represented by the following formula (1) is preferable.

[Chemical Formula 1]

The preferred content of the component (A), the component (B), the component (C), the component (D) and the component (E) is 10 to 45 wt%, 5 to 35 wt%, 5 to 35 wt% , 2 to 20 wt%, and 2 to 6 wt%.

As the component (D), a polymer containing 5 to 95% by weight of the monomer (d1), 5 to 95% by weight of the monomer (d2) and 0 to 80% by weight of the monomer (d3) desirable.

As the component (D), a compound having as a monomer (d3) 0 to 60% by weight of styrene and / or a hydrocarbon group having 1 to 10 carbon atoms and 1 acryloyl group (hereinafter referred to as "monofunctional Quot; acrylate ") in an amount of 0 to 40% by weight.

As the component (D), 10 to 60% by weight of glycidyl methacrylate as the monomer (d1), 10 to 80% by weight of methyl methacrylate as the monomer (d2) It is preferable that the monomer (d3) contains a polymer obtained by high-temperature polymerization at a temperature of 160 DEG C or higher, containing 1 to 50% by weight of styrene.

As another preferred example, the component (D) is a copolymer comprising 10 to 60% by weight of glycidyl methacrylate as the monomer (d1), 10 to 80% by weight of methyl methacrylate as the monomer (d2) And 1 to 30% by weight of a monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms as the monomer (d3), and polymerizing at a high temperature of 160 占 폚 or higher.

The radical polymerizable component such as the component (A) contained in these photocurable adhesive compositions can be cured by radicals generated when the component (E) is decomposed into light, but in order to obtain a sufficient reaction rate with a small irradiation dose, F) as a photo-radical polymerization initiator in a proportion of 10% by weight or less. In order to obtain a coating surface excellent in smoothness, these photocurable adhesive compositions preferably contain 0.01 to 0.5% by weight of a leveling agent as a component (G) in the composition.

According to the present invention, there is also provided a polarizer comprising a polyvinyl alcohol-based resin film, wherein a protective film composed of a transparent resin film selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is bonded via an adhesive As the polarizing plate, there is provided a polarizing plate in which the adhesive is formed of any of the above-mentioned photocurable adhesive compositions.

The polarizing plate is provided with an adhesive applying step of applying any of the above-described photocurable adhesive compositions onto at least one of the laminated surfaces of the polarizer and the protective film, an adhesion step of bonding the polarizer and the protective film via the obtained adhesive layer, And a curing step of curing the photocurable adhesive composition in a state in which the polarizer and the protective film are bonded to each other. Specifically, there is a method of applying an uncured, photo-curable adhesive composition to a polarizer, then attaching a protective film to the adhesive composition coating surface, and then curing the adhesive composition to form an adhesive layer; A method of applying a curable adhesive composition and then applying a polarizer to the applied surface of the adhesive composition and then curing the adhesive composition to form an adhesive layer; a method of softening the uncured curable adhesive composition between the polarizer and the protective film, A method in which the adhesive composition is uniformly pressed and diffused by placing the adhesive layer between rolls and the like, and then the adhesive composition is cured to form an adhesive layer.

According to the present invention, there is also provided an optical member in which an optical layer exhibiting an optical function different from that of the above-mentioned polarizing plate is laminated. The other optical layer in this case preferably includes a retarder. And a liquid crystal display device in which the optical member is disposed on one side or both sides of the liquid crystal cell.

INDUSTRIAL APPLICABILITY When the polarizing plate having a protective film of a resin film having low moisture permeability selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is produced, the photo-curing adhesive composition of the present invention, Excellent curability, good final adhesive strength after a lapse of a predetermined time, and does not cause problems such as appearance failure even after the durability test, and is excellent in adhesion strength after completion of the anti-wet heat test.

The adhesive composition of the present invention is particularly useful when the protective film is composed of an acrylic resin. Further, the adhesive composition of the present invention is excellent in peeling test in which the peeling strength is weakened when an acrylic resin and a polarizer are bonded, that is, when the acrylic resin is fixed on a smooth plate and the peeling test when the polarizer is bent . Therefore, it is excellent in that it is not peeled off well in the processing step.

Further, since the adhesive composition of the present invention has a very low viscosity, it is easy to apply it thinly and to bond it without defects. The polarizing plate obtained by bonding the polarizer and the protective film through the adhesive composition is not only cured by a short time process of light irradiation but also has an adhesive strength of a certain strength even after the light irradiation, .

Further, an optical member in which this polarizing plate is combined with another optical layer can form a liquid crystal display device having excellent reliability.

Hereinafter, the present invention will be described in detail. In the present invention, in adhering a protective film made of a transparent resin film to a polarizer made of a polyvinyl alcohol-based resin film, a photo-curable adhesive composition having a specific composition is used. In this manner, the polarizer and the protective film are bonded to each other via the photo-curable adhesive composition to obtain a polarizing plate. This polarizing plate can be laminated with an optical layer having another optical function to make an optical member. The optical member can be disposed on at least one side of the liquid crystal cell to make a liquid crystal display device. Hereinafter, explanation will be made in the order of the photo-curable adhesive composition, the polarizing plate, the method of producing the polarizing plate, the optical member, and the liquid crystal display.

[Photocurable adhesive composition]

In the present invention, a photo-curable adhesive composition having a specific composition is used for bonding the polarizer and the protective film. Hereinafter, this photocurable adhesive composition may be simply referred to as "photocurable adhesive" or "composition". The photocurable adhesive of the present invention essentially contains five components (A), (B), (C), (D) and (E)

(A) a poly (meth) acrylate of a polyol having 2 to 15 carbon atoms

(B) a polyglycidyl ether of a polyol having 2 to 10 carbon atoms

(C) a compound having a molecular weight of 500 or less and having at least two oxetanyl groups in one molecule

(D) a polymer comprising a monomer (d1), a monomer (d2) and optionally a monomer (d3) as constituent monomer units, a polymer produced by high temperature polymerization of these monomers and having a Tg of 20 ° C or more and Mw Is from 1,000 to 30,000

(E) a photocathode polymerization initiator

In the present specification, (meth) acrylate means acrylate or methacrylate, and (meth) acryloyl group means acryloyl or methacryloyl group.

In the present specification, the poly (meth) acrylate of the above (A) is also referred to as "component (A)" or "poly (meth) acrylate (A) (C) "or" oxetane compound (C) ", and the polymer having an epoxy group in the above (D) is referred to as" an epoxy compound Component (D) ", and the photocationic polymerization initiator (E) is also referred to as" component (E) "or" photocationic polymerization initiator (E) ".

The content of the components (A) to (E) in the composition is from 5 to 50% by weight, the component (B) is from 5 to 45% by weight, the component (C) 1 to 25% by weight of component (D), and 0.5 to 10% by weight of component (E).

The photocurable adhesive may optionally contain a photo radical polymerization initiator as the component (F), and it is preferable that the content is 10% by weight or less. As the component (G), a leveling agent may be contained.

In the present specification, the photo radical polymerization initiator (F) is also referred to as "component (F)" or "photo radical polymerization initiator (F)", and the leveling agent of (G) (G) ".

≪ Poly (meth) acrylate (A) >

In the photocurable adhesive of the present invention, the poly (meth) acrylate to be the component (A) is a poly (meth) acrylate of a polyol having 2 to 15 carbon atoms.

(Meth) acrylate having a number of (meth) acryloyl groups in the molecule tends to lack durability such as resistance to cold and heat cycles.

By using the component (A), the adhesive force and durability to the protective film are excellent while lowering the viscosity of the composition. As the component (A), a di (meth) acrylate of a diol having 2 to 10 carbon atoms is more preferable in terms of low viscosity, adhesive strength, and durability. Further, (meth) acrylate is preferable because acrylate is curable.

Specific examples of the component (A) include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 3-methyl- Ethyl (meth) acrylate, 1,9-nonanediol di (meth) acrylate, ethyleneglycol di (meth) acrylate, Acrylate, propylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di Acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol trie or tetra (meth) acrylate, (Meth) acrylate, di Other erythritol, and the like erythritol penta or hexa (meth) acrylate, and di (meth) acrylate of a hydrogenated bisphenol A.

The component (A) may have an ester skeleton or an isocyanurate skeleton. Specific examples of the compound having an ester skeleton include neopentyl glycol, an esterification reaction product of hydroxypivalic acid and (meth) acrylic acid, and examples of the compound having an isocyanurate skeleton include isocyanuric acid And di- or tri (meth) acrylates of acid alkylene oxide adducts.

Of these, the esterification reaction products of 1,6-hexanediol di (meth) acrylate and neopentyl glycol, hydroxypivalic acid and (meth) acrylic acid are excellent in low viscosity, adhesion and durability, .

The content of the component (A) is in the range of 5 to 50% by weight based on the whole composition. By setting this ratio, the curability, the final adhesive force, and the durability can be improved. By setting the content of the component (A) in the range of 10 to 45% by weight, the adhesive strength can be further improved.

≪ Epoxy Compound (B) >

In the photocurable adhesive of the present invention, the epoxy compound as the component (B) is a polyglycidyl ether of a polyol having 2 to 10 carbon atoms.

An epoxy compound having a number of glycidyl ether groups in the molecule is liable to have poor durability such as adhesive strength and cold and heat cycle resistance.

By using the component (B), the adhesive force to the polarizer is excellent while the viscosity of the composition is lowered. Here, as the component (B), a diglycidyl ether of a diol having 2 to 10 carbon atoms (provided that the polyether diol having 3 or more repeating number of alkylene oxide units is excluded) , And it is more preferable that the adhesive force is excellent.

Specific examples of the component (B) include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6- Hexanediol diglycidyl ether, cyclohexanedimethyloliglycidyl ether, 1,9-nonanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, hydroquinone Trimethylolpropane triglycidyl ether, pentaerythritol tri or tetraglycidyl ether, and di- or triglycidyl ether of isocyanuric acid ethylene oxide adduct, and the like. .

Of these, alkanediol diglycidyl ethers having 2 to 10 carbon atoms are particularly preferable in view of low viscosity and adhesion.

The content of the component (B) is in the range of 5 to 45% by weight based on the whole composition. By setting this ratio, the curability, the final adhesive force, and the adhesive strength after the anti-wet heat test can be improved. In this respect, the content of the component (B) is preferably 5 to 35% by weight, more preferably 10 to 35% by weight, and still more preferably 15 to 35% by weight.

≪ Oxetane compound (C) >

In the photocurable adhesive of the present invention, the oxetane compound serving as the component (C) is a compound having a molecular weight of 500 or less and having at least two oxetanyl groups in one molecule.

Specific examples of the component (C) include bis [(3-ethyloxetan-3-yl) methyl] ether, bis [ Methyl] benzene, 1,4-bis [(3-ethyloxetan-3-yl) Methoxy] benzene, 1,2-bis [(3-ethyloxetan-3-yl) methoxy] , Bis [(3-ethyloxetan-3-yl) methoxy] biphenyl, 1,1'-bis [ Methoxy] propane, 1,2-bis [(3-ethyloxetan-3-yl) methoxy] ethane, 2,2-bis { Methoxy] methyl} propane, 1,2-bis [(3-ethyloxetan-3-yl) methoxy] propane, 1,4- Ethyloxetan-3-yl) methoxy] butane and 1,6-bis [(3-ethyloxetan-3-yl) methoxy] hexane.

As the component (C), a composition in which a compound having two oxetanyl groups in one molecule and a compound having a molecular weight of 150 to 400 are obtained has a low viscosity, and a cured product is more preferable because of its excellent adhesive strength. 150 to 300.

As the component (C), bis [(3-ethyloxetan-3-yl) methyl] ether, that is, an oxetane compound represented by the following formula (1) is particularly preferable.

(2)

The content of the component (C) is in the range of 5 to 45% by weight based on the whole composition. By setting this ratio, the curability, the final adhesive force, the adhesive force after the anti-wet heat test, and the durability can be improved. By mixing an appropriate amount of the component (C), the adhesion to various kinds of base materials is improved, but the adhesion to a protective film made of acrylic resin is remarkably improved.

When the content of the component (C) is less than 5% by weight, the adhesive force immediately after the light irradiation and the final adhesive force are insufficient. On the other hand, if it exceeds 45% by weight, the adhesive force to the polarizer decreases.

The content of the component (C) is preferably from 5 to 35% by weight, and more preferably from 10 to 30% by weight, from the viewpoint that the adhesive strength is more excellent.

<Polymer (D) Having an Epoxy Group>

In the photocurable adhesive of the present invention, by containing the component (D), the curing property and the adhesive strength can be improved even when the humidity at the time of applying the adhesive is high.

As the component (D), a polymer containing monomer (d1), monomer (d2) and optionally monomer (d3) as constituent monomer units and having a Tg of 20 ° C And a polymer having Mw of 1,000 to 30,000, various polymers can be used.

The component (D) has a Tg of 20 ° C or higher, preferably 30 ° C or higher, and more preferably 40 to 100 ° C. In a polymer having a Tg of less than 20 캜, the adhesive force becomes insufficient. In the present invention, Tg means a value measured at a heating rate of 10 ° C / minute using a differential scanning calorimeter (DSC).

The component (D) has a Mw of 1,000 to 30,000, preferably 3,000 to 20,000, and more preferably 5,000 to 15,000. When the Mw of the component (D) is less than 1,000, the adhesive force between the polarizer and the polarizer protective film is reduced. When the Mw of the component (D) is more than 30,000, the coating property is lowered.

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

Component (D) is a polymer obtained by high temperature polymerization.

The component (D) is a polymer having a low Mw. If a polymer having such low Mw is to be produced by a usual polymerization method, it is usually necessary to increase the chain transfer agent and the polymerization initiator. If a polymer using a chain transfer agent in a large amount is used, the cationic curability and adhesive force of the composition tend to be lowered. If a polymer containing a large amount of a polymerization initiator is used, the storage stability of the composition tends to be lowered. For this reason, a polymer produced by high-temperature polymerization which does not require a large amount of chain transfer agent or polymerization initiator is required.

The temperature for the high-temperature polymerization is preferably 160 占 폚 or higher, more preferably 160 占 폚 to 350 占 폚, and particularly preferably 180 占 폚 to 300 占 폚.

Among high temperature polymerization, high temperature continuous polymerization is preferable. High-temperature continuous polymerization is advantageous not only in productivity, but also in that the composition distribution in the copolymer product is not well formed, and therefore excellent compatibility is obtained.

The high-temperature continuous polymerization can be carried out by a known method (for example, Japanese Unexamined Patent Publication No. 57-502171, Japanese Unexamined Patent Publication No. 59-6207, Japanese Unexamined Patent Publication No. 60-215007, etc.).

Specifically, after a pressurizable reactor is filled with a solvent and set at a predetermined temperature under pressure, a monomer mixture, or a monomer mixture composed of a polymerization solvent and a polymerization initiator, if necessary, is fed to the reactor at a constant feed rate, And a method of extracting the reaction solution in an amount suitable for the reaction.

The component (D) is a polymer having the monomer (d1) and the monomer (d2) as essential constituent monomer units and is a polymer having an epoxy group and can be copolymerized with the component (B) and the component (C) which are the cationically curable compounds.

The monomer (d1) is a compound having an epoxy group and an ethylenic unsaturated group.

Examples of the ethylenic unsaturated group in the monomer (d1) include a vinyl group and a (meth) acryloyl group.

Specific examples of the monomer (d1) include glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate.

(d1), glycidyl methacrylate is particularly preferable.

The monomer (d2) is a compound having a hydrocarbon group having 1 to 10 carbon atoms and is a compound having one methacryloyl group (hereinafter referred to as "monofunctional methacrylate").

Specific examples of the monomer (d2) include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, Acrylate, isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate Isodecyl methacrylate, benzyl methacrylate, and the like.

As the monomer (d2), among these compounds, a monofunctional methacrylate having a hydrocarbon group of 1 to 6 carbon atoms is preferable, and more preferable is methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate and benzyl methacrylate And particularly preferably methyl methacrylate.

The weight ratio of the monomer (d1) and the monomer (d2) contained in the component (D) as the constituent monomer unit is preferably 5 to 95% by weight and 5 to 95% by weight, respectively, in the total constituent monomer units. With this range, the adhesive composition is excellent in adhesion even when it is coated under high humidity.

A more preferable weight ratio of the monomer (d1) and the monomer (d2) contained in the component (D) as the constituent monomer unit is 10 to 60% by weight and 10 to 80% by weight, respectively, 20 to 50% by weight and 20 to 70% by weight. Further, when the total of the monomers (d1) and (d2) is less than 100% by weight, it means a polymer containing the monomer (d3) as a constituting monomer.

As the component (D), a monomer (d3) which is a compound having one ethylenic unsaturated group other than the monomer (d1) and the monomer (d2) may be contained as a constituent monomer unit, if necessary.

The weight ratio of the monomer (d3) contained in the component (D) is preferably from 0 to 80% by weight, and more preferably from 0 to 60% by weight, based on the total constituent monomer units.

Examples of the ethylenic unsaturated group in the monomer (d3) include a vinyl group and a (meth) acryloyl group.

As the monomer (d3), various compounds can be used as long as it is a monomer other than the monomer (d1) and the monomer (d2), and an aromatic group-containing vinyl compound such as styrene and -methylstyrene, (Hereinafter referred to as "monofunctional acrylate"), (meth) acrylonitrile, and (meth) acrylamide.

Among these compounds, monomers (d3) are preferably monofunctional acrylates having styrene and / or a hydrocarbon group of 1 to 10 carbon atoms.

When the monomer (d3) contains styrene, the content of styrene contained in the component (D) is preferably 60% by weight or less (0 to 60% by weight), more preferably 1 to 50 By weight, more preferably 5 to 45% by weight, and particularly preferably 10 to 40% by weight. When the content is in this range, the adhesive strength of the adhesive composition when applied under a high humidity is more excellent.

When the monomer (d3) contains a monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms, specific examples of the monofunctional acrylate include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, Butyl acrylate, isobutyl acrylate, isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, nonyl acrylate, Isononyl acrylate, decyl acrylate, isodecyl acrylate, and benzyl acrylate.

Among these compounds, methyl acrylate, ethyl acrylate, cyclohexyl acrylate and benzyl acrylate are preferable, and methyl acrylate is more preferable.

When the monomer (d3) contains a monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms, the content ratio of the monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms contained in the component (D) Is preferably 40% by weight or less (0 to 40% by weight), more preferably 1 to 30% by weight, and still more preferably 5 to 25% by weight. When the content is in this range, the adhesive strength of the adhesive composition when applied under a high humidity is more excellent.

More preferred examples of the component (D) include 10 to 60% by weight of glycidyl methacrylate as the monomer (d1), 10 to 80% by weight of methyl methacrylate as the monomer (d2) And 1 to 50% by weight of styrene as the monomer (d3) and polymerizing at a high temperature of 160 DEG C or higher.

As another preferred example, the component (D) is a copolymer comprising 10 to 60% by weight of glycidyl methacrylate as the monomer (d1), 10 to 80% by weight of methyl methacrylate as the monomer (d2) And 1 to 30% by weight of a monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms as the monomer (d3), and polymerizing at a high temperature of 160 占 폚 or higher.

The content of the component (D) contained in the adhesive composition of the present invention should be 1 to 25% by weight, preferably 2 to 20% by weight, more preferably 5 to 20% by weight, To 15% by weight. (D) in a proportion of 1 to 25% by weight, it is possible to improve the adhesive force immediately after the light irradiation, the final adhesive force and the adhesive force after the anti-wet heat test.

&Lt; Optical cationic polymerization initiator (E) >

The photocurable adhesive of the present invention is a curable composition comprising an epoxy compound (B), an oxetane compound (C), a polymer (D) having an epoxy group, and an epoxy compound or oxetane In view of containing a compound, a photocationic polymerization initiator is blended as the component (E). The photo cationic polymerization initiator generates a cationic species or Lewis acid by irradiation of an active energy ray such as visible light, ultraviolet ray, X-ray or electron ray to initiate polymerization reaction of an epoxy group or an oxetanyl group.

(C) can be cured at room temperature by blending a photocationic polymerization initiator as the component (E), and it is possible to satisfactorily adhere the protective film by reducing heat resistance of the polarizer and deformation due to expansion or contraction. The photocathione polymerization initiator acts catalytically by irradiation of an active energy ray. Therefore, the photocathione polymerization initiator is preferably used in combination with an epoxy compound (B), an oxetane compound (C), a polymer (D) having an epoxy group, Even when mixed with an oxetane compound, storage stability and workability are excellent. Examples of the compound capable of generating a cationic species or a Lewis acid by irradiation with an active energy ray include an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt and an aromatic sulfonium salt, and an iron-arene complex.

As the aromatic diazonium salt, for example, the following compounds can be mentioned.

Benzene diazonium hexafluoroantimonate, benzene diazonium hexafluoroantimonate,

Benzene diazonium hexafluorophosphate,

Benzene diazonium hexafluoroborate and the like.

As the aromatic iodonium salt, there may be mentioned, for example, the following compounds.

Diphenyl iodonium tetrakis (pentafluorophenyl) borate,

Diphenyl iodonium hexafluorophosphate,

Diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroantimonate,

Di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

As the aromatic sulfonium salt, for example, the following compounds can be mentioned.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium tetrakis (pentafluorophenyl) borate,

4,4'-bis (diphenylsulfono) diphenyl sulfide bis hexafluorophosphate,

4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,

4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,

7- (di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,

4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate,

4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate,

4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

The iron-arene complexes include, for example, the following compounds.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron (II) -tris (trifluoromethylsulfonyl) methanide, and the like.

Each of these photocathione polymerization initiators may be used singly or in combination of two or more kinds thereof. Among them, an aromatic sulfonium salt is preferably used since it has an ultraviolet ray absorption property in a wavelength range of 300 nm or more, and is excellent in curability and can give a cured product having good mechanical strength and adhesive strength.

(EI) can be obtained commercially. For example, "KAYARAD PCI-220", "KAYARAD PCI-620" (manufactured by Nippon Kayaku Co., Ltd.), "UVI CIT-1370 " (trade name, manufactured by Dow Chemical), "ADEKA OPTOMER SP-150 & DPI-101 "," DPI-102 "and" DPI-2064S "(all manufactured by Nippon Soda Co., Ltd.)," CIP-1882S "," CIP- 101, BBI-102, BBI-103, BBI-105, TPS-101, DPI-105, MPI-103, MPI-105, DPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," (Manufactured by Rhodia), "Irgacure 250", "Irgacure PAG103", "Irgacure PAG108", "Irgacure PAG121", "Irgacure PAG203" (Manufactured by BASF), "CPI-100P", "CPI-101A", "CPI-210S" and "CPI-110P"

Among them, a product which does not contain propylene carbonate which is often used as a solvent for the component (E) is more preferable since it has excellent adhesion with a protective film such as acrylic resin.

The content of the component (E) 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 curing of the adhesive becomes insufficient and the mechanical strength and the adhesive strength are lowered. On the other hand, if the ratio exceeds 10% by weight, the ionic substance in the cured product increases, And the durability is deteriorated, which is not preferable. The content of the component (E) is more preferably 2 to 6% by weight. By containing the component (E) in an amount of 2% by weight or more, the adhesive strength when the adhesive composition is applied under a high humidity is more excellent. By containing not more than 6% by weight of component (E), optical properties such as transparency and durability performance can be improved.

&Lt; Photo radical polymerization initiator (F) >

The radical-curable component such as the component (A) contained in the photocurable adhesive of the present invention can be cured with a radical generated when the component (E) is decomposed by light, but in order to obtain a sufficient reaction rate with a small irradiation dose, It is preferable to blend a photo radical polymerization initiator as the component (F). (F) is preferably 10% by weight or less, more preferably 0.1 to 10% by weight, and still more preferably 0.1 to 5% by weight based on the whole composition. When the blending amount exceeds 10% by weight, the durability may be lowered, which is not preferable.

Specific examples of the component (F) include, for example, the following compounds.

Dichloroacetophenone, 4'-tert-butyl-2,2-dichloroacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2- -Methylthiophenyl) -2-morpholinopropane-1-one, 1-hydroxycyclohexyl phenyl ketone,?,? - diethoxyacetophenone, 2-hydroxy- 2-methylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy- , 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methylpropan- ) Butan-1-one;

Benzoin ether-based photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

Benzophenone-based photopolymerization initiators such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, and 2,4,6-trimethylbenzophenone;

Thioxanthone photopolymerization initiators such as 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, and 1-chloro-4-propanedioxanthone;

Trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, and bis (2,4,6-trimethylbenzoyl) phenyl An acylphosphine oxide-based photopolymerization initiator such as phosphine oxide;

Oxime ester-based photopolymerization initiators such as 1- [4- (phenylthio) phenyl] -1,2-octanedione 2- (O-benzoyloxime);

Camphorquinone and the like.

The component (F) may be used singly or in combination of two or more depending on the desired performance.

When the photo-radical polymerization initiator of component (F) is blended, the content thereof is preferably 10% by weight or less, more preferably 0.1 to 10% by weight, more preferably 0.1 to 10% by weight, 5% by weight. When the content ratio of the photo radical polymerization initiator (F) is within the above range, sufficient adhesive strength is obtained and the curing property is also excellent.

&Lt; Leveling agent (G) >

In the photocurable adhesive of the present invention, it is preferable to contain a leveling agent of the component (G) for the purpose of obtaining a coating surface excellent in smoothness.

Examples of the component (G) include silicone leveling agents and fluorine leveling agents, and various commercially available leveling agents can be used.

The preferable content of the component (G) is 0.01 to 0.5% by weight based on the whole composition. By setting the amount in the above range, the effect of adding the leveling agent is sufficiently obtained and the adhesion is excellent.

<Other Curable Component>

The photocurable adhesive of the present invention may contain other cateine curing component or radical curing component in addition to the components (A) to (G) described above.

Examples of the cationic curing component other than the component (B), the component (C) and the component (D) include various epoxy compounds, oxetane compounds, and vinyl ether compounds.

Specific examples of the epoxy compound other than the component (B) and the component (D) include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) Adipate, a caprolactone-modified product of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, an esterified product of a polycarboxylic acid and 3,4-epoxycyclohexylmethyl alcohol or a caprolactone-modified product thereof , Diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of brominated bisphenol A, phenol novolak type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, terephthalic acid Diglycidyl ester, phthalic acid diglycidyl ester, an addition reaction product of a terminal carboxylic acid polybutadiene and a bisphenol A type epoxy resin, dicyclopentadiene dioxide, limonene dioxide, 4-vinylcyclohexene dioxy Polyglycidyl ether, diglycidyl ether of polyethylene glycol (6 or more repeating number) diglycidyl ether, diglycidyl ether of polypropylene glycol (repeating number 4 or more), diglycidyl ether of polytetramethylene glycol (repeating number 3 or more), hydrogenated bisphenol Epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxysilane, 3- Propyl trimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, polybutadiene diglycidyl ether of both terminal hydroxyl groups, internal epoxide of polybutadiene, a compound in which a double bond of styrene-butadiene copolymer is partially epoxidized (For example, "Epofriend ", manufactured by Daicel Chemical Industries, Ltd.) and a compound in which an isoprene unit of an ethylene-butylene copolymer and a block copolymer of polyisoprene is partially epoxidized "L-20 " 7 ").

Specific examples of the oxetane compound other than the component (C) include monofunctional oxetane containing an alkoxyalkyl group such as 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl- Hydroxymethyloxetane, 3-chloromethyl-3-ethyloxane of a novolak type phenol-formaldehyde resin, and the like. 3-yl) methoxy] propyl trimethoxysilane, 3 - [(3-ethyloxetan-3-yl) methoxy] propyl tri Condensation reaction of 3-ethyloxetane-3-ylmethanol with silane tetraol condensate, hydrolysis condensation product of 3 - [(3-ethyloxetan-3-yl) methoxy] propyltrialkoxysilane, And the like.

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, triethylene glycol divinyl ether, cyclohexane Dimethanol divinyl ether, and the like.

The content of the cationically curable component other than the component (B), the component (C), and the component (D) is preferably less than 30% by weight, more preferably less than 15% by weight based on the whole composition.

Examples of the radical-curable component other than the component (A) include various compounds, and examples thereof include (meth) acrylates, (meth) acrylamides, maleimides, (meth) acrylic acid, (Meth) acrylic aldehyde, N-vinyl-2-pyrrolidone, triallyl isocyanurate, divinyl adipate, and vinyltrimethoxysilane.

Specific examples of the (meth) acrylates having one (meth) acryloyl group in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (Meth) acrylate, isooctyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, cyclohexyl (Meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl (Meth) acrylate, benzyl (Meth) acrylate of a phenol alkylene oxide adduct, (meth) acrylate of a p-cumylphenol alkylene oxide adduct, (meth) acrylate of an o-phenylphenol alkylene oxide adduct, nonylphenol alkyl (Meth) acrylate of an alkylene oxide adduct of 2-methoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate and 2-ethylhexyl alcohol, Mono (meth) acrylate of triethylene glycol, mono (meth) acrylate of triethylene glycol, mono (meth) acrylate of tetraethylene glycol, mono (meth) , Mono (meth) acrylates of polyethylene glycol, mono (meth) acrylates of dipropylene glycol, mono (meth) acrylates of tripropylene glycol, polypropylene (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, tetrahydrofurfuryl , Caprolactone modified tetrahydrofurfuryl (meth) acrylate, (2-ethyl-2-methyl-1,3-dioxolane- (Meth) acrylate, glycidyl (meth) acrylate, methyl (meth) acrylate, (Meth) acryloyloxyethyl isocyanate, allyl (meth) acrylate, (meth) acryloyloxyethyl isocyanate, Acrylates such as N- (meth) acryloyloxyethylhexahydrophthalimide, N- (meth) acryloyloxyethyltetrahydrophthalimide, 2- (meth) acryloyloxyethylhexa (Meth) acryloyloxyethyl succinic acid, ω-carboxy-polycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, 3- (Meth) acryloyloxypropyldimethoxymethylsilane, 3- (meth) acryloyloxypropyltriethoxysilane, and the like can be given.

Specific examples of (meth) acrylates other than the component (A) having two or more (meth) acryloyl groups in the molecule (hereinafter referred to as "polyfunctional (meth) acrylate") include polyethylene glycol Di (meth) acrylate, urethane (meth) acrylate, urethane (meth) acrylate of di (meth) acrylate, polypropylene glycol (Meth) acrylate, and epoxy (meth) acrylate. Examples of polyester (meth) acrylates having three or more (meth) acryloyl groups include dendrimer type (meth) acrylates.

Specific examples of the (meth) acrylamides include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-methylol (Meth) acrylamide, N, N-diallyl (meth) acrylamide, (meth) acrylamide, ) Acryloylmorpholine, and the like.

Specific examples of the maleimide include N-methylmaleimide, N-hydroxyethylmaleimide, N-hydroxyethyl citraconimide, urethane of N-hydroxyethyl citraconimide and isophorone diisocyanate Reactants and the like.

The content of the radical-curing component other than the component (A) is preferably less than 20% by weight based on the entire composition.

&Lt; Other components not having curability >

The photo-curable adhesive of the present invention may optionally contain other components that do not have curability within the range not impairing the effects of the present invention. Specific examples thereof include photosensitizers, thermal cation polymerization initiators, D), other polyol compounds, water, and the like.

Specific examples of the photosensitizer include benzophenone, methyl o-benzoylbenzoate, 2-isopropylthioxanthone, and 9,10-dibutoxyanthracene. Among these, there are compounds corresponding to the photo radical polymerization initiator of the component (F), but the photosensitizer mentioned here functions as a sensitizer for the photocathon polymerization initiator of the component (E). These may be used alone or in combination of two or more.

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

Specific examples of the thermal cation polymerization initiator include benzylsulfonium salts, thiophenium salts, thiolanium salts, benzylammonium salts, pyridinium salts, hydrazinium salts, carboxylic acid esters, sulfonic acid esters and amine imides . These initiators can be commercially available. For example, "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (manufactured by ADEKA Co., Ltd.) and "CI-2639" (Manufactured by Nippon Soda Co., Ltd.), "San-ai SI-60L", "San-ai SI-80L" and "San- ) And the like.

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

The photocurable adhesive of the present invention may be blended with a polymer (hereinafter referred to as "component (D)") other than the component (D) for the purpose of increasing the adhesive strength in the test method for inserting the blade of the cutter.

(D) 'may be used as the component (D). However, it is preferable that the composition contains 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms as a constituent monomer unit and has an Mw of 1,000 to 200,000 ) &Quot; component &quot;) is preferable because the final adhesive force to the polarizer is excellent.

Specific examples of the alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms include a compound having an alkyl group in the monofunctional acrylate having a hydrocarbon group of 1 to 10 carbon atoms in the monomer (d3).

(D1) 'component may be a copolymer of alkyl methacrylate and other monomers as long as alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms is contained in an amount of 60% by weight or more as constituting monomer units.

(D1) 'component is preferably a polymer having a Tg of 10 DEG C or lower, more preferably a polymer having a Tg of -80 DEG C to 0 DEG C is preferable because the adhesive strength of the blade in the test method for inserting the blade of the cutter is increased Do.

(D1) 'component may be a block copolymer of an alkyl acrylate containing an alkyl group of 1 to 10 carbon atoms and an alkyl methacrylate or other monomer [hereinafter referred to as "(D1-1)' component") .

(D1-1) 'component is preferably a combination of a block polymer having a polyacrylate block unit and a polymethacrylate block unit, and a block unit of a polymer of a polyacrylate block unit and another monomer And the like.

Among these, a block polymer having a polyacrylate block unit and a polymethacrylate block unit, or a block polymer containing polybutyl acrylate and polymethyl methacrylate as a block unit is preferable.

As the component (D1-1) ', there can be used those produced by the polymerization of a conventional method using the above monomers, and examples thereof include radical polymerization, living anion polymerization, living radical polymerization, . Examples of the polymerization method include a solution polymerization method, an emulsion polymerization method, a suspension polymerization method and a bulk polymerization method.

(D1-1) 'are commercially available, and Kurari (LA1114, LA2140e, LA2330, LA2250) manufactured by Kuraray Co., Ltd. can be mentioned.

(D) 'is preferably from 1 to 15% by weight, more preferably from 1 to 8% by weight in the composition.

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

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

The viscosity of the photocurable adhesive of the present invention is preferably 150 mPa · s or less at 25 ° C. and preferably 100 mPa · s or less at 25 ° C. in order to obtain a coating property that is excellent in coating properties usable in a polarizing plate manufacturing process, s or less. More preferably 50 mPa 占 퐏 or less.

To the photo-curable adhesive of the present invention, a small amount of water may be added in order to improve the adhesive force to the polarizer having a high degree of drying. In this case, the amount of water added is preferably less than 3% by weight, more preferably less than 1% by weight based on the whole composition.

In addition to these, an ion trap agent, an antioxidant, a light stabilizer, a chain transfer agent, a tackifier, a thermoplastic resin, a metal oxide fine particle, a defoaming agent, a pigment, an organic solvent and the like may be blended.

[Polarizer]

The above-described photocurable adhesive is used for adhering a protective film to a polarizer made of a polyvinyl alcohol-based resin film, and preferably a monoaxially stretched polarizing film made of a polyvinyl alcohol-based resin film in which a dichromatic dye is adsorbed and oriented And a protective film is adhered to the polarizer in this way to form a polarizing plate. That is, the polarizing plate related to the present invention is a polarizing plate formed by a uniaxially stretched polyvinyl alcohol based resin film in which a dichroic dye is adsorbed and aligned, and a protective film is applied to the polarizer. The protective film may be applied only to one side of the polarizer, or may be applied to both sides of the polarizer. When the protective film is laminated on both surfaces of the polarizer, the respective protective films may be made of the same kind of resin or may be made of different types of resins.

<Polarizer>

The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, polyvinyl acetate, which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and other monomers copolymerizable therewith, and the like are exemplified. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and the like. The saponification degree of the polyvinyl alcohol-based resin is preferably 85 to 100 mol%, more preferably 98 to 100 mol%. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol-based resin is preferably in the range of 1,000 to 10,000, more preferably 1,500 to 10,000.

The polarizing plate may be prepared by a process comprising the steps of uniaxially stretching a polyvinyl alcohol resin film as described above, a step of dying a polyvinyl alcohol resin film with a dichroic dye, a step of adsorbing the dichroic dye, a step of dying a polyvinyl alcohol- A step of treating the resin film 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 applying a protective film to the uniaxially stretched polyvinyl alcohol-based resin film .

The uniaxial stretching may be carried out before dyeing with a dichroic dye, or simultaneously with dyeing with a dichroic dye, or after dyeing with a dichroic dye. In the case where uniaxial stretching is carried out after dyeing with a dichroic dye, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching at these plural stages. In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls having different circumferential speeds, or may be uniaxially stretched using a heat roll. In addition, it may be dry stretching in which drawing is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen with a solvent. The draw ratio is preferably about 4 to 8 times.

In order to dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, a polyvinyl alcohol-based resin film may be dipped in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically iodine or dichroic dye is used.

When iodine is used as the dichroic dye, a method of dying and dyeing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide is preferably employed. The content of iodine in this 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 about 0.5 to 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution is preferably about 20 to 40 占 폚, and the immersion time for 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 dipped in an aqueous solution containing a water-soluble dichroic dye and is dyed is preferably adopted. The content of the dichroic dye in the aqueous solution is preferably about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is preferably about 20 to 80 占 폚, and the immersion time for the aqueous solution is preferably about 30 to 300 seconds.

The boric acid treatment after dyeing with the dichroic dye is carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution of boric acid. The content of boric acid in the aqueous solution of boric acid 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 solution of boric acid preferably contains potassium iodide. The content of potassium iodide in the aqueous solution of boric acid is preferably about 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time for the boric acid aqueous solution is preferably about 100 to 1,200 seconds, more preferably about 150 to 600 seconds, and still more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is preferably 50 占 폚 or higher, and more preferably 50 to 85 占 폚.

The polyvinyl alcohol-based resin film after boric acid treatment is subjected to water washing treatment. The water washing treatment is preferably carried out, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. After washing with water, drying treatment is carried out to obtain a polarizer. The temperature of water in the water washing treatment is preferably about 5 to 40 占 폚, and the immersing time is preferably about 2 to 120 seconds. The drying treatment to be performed thereafter is preferably carried out using a hot-air dryer or a far-infrared heater. The drying temperature is preferably 40 to 100 占 폚. The treatment time in the drying treatment is preferably about 120 to 600 seconds.

In this manner, a polarizer comprising a polyvinyl alcohol-based resin film in which iodine or dichromatic dye as a dichroic dye is adsorbed and oriented can be obtained.

<Protection film>

Next, the polarizer is adhered to one side or both sides of the protective film using the above-described photo-curable adhesive. The triacetyl cellulose film widely used as a protective film for a polarizer generally has a moisture permeability of about 400 g / m 2/24 hr. In the present invention, as a protective film to be adhered to at least one surface of a polarizer, triacetyl cellulose As the resin exhibiting a low moisture permeability, a polyester resin, a polycarbonate resin, an acrylic resin, or an amorphous polyolefin resin is employed.

The kind 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 and cost. The polyethylene terephthalate means a resin in which at least 80 mol% of the repeating units are composed of ethylene terephthalate, and may contain a constituent unit derived from another copolymerization component. Examples of other copolymerization components include isophthalic acid, p- beta -hydroxyethoxybenzoic acid, 4,4'-dicarboxy diphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) Dicarboxylic acid components such as acid, sebacic acid, 5-sodium sulfoisophthalic acid, and 1,4-dicarboxycyclohexane; Diol components such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These dicarboxylic acid components and diol components may be used in combination of two or more kinds, if necessary. In addition to the dicarboxylic acid component and the diol component, a hydroxycarboxylic acid such as p-hydroxybenzoic acid may be used in combination. As other copolymerization components, a small amount of a dicarboxylic acid component and / or a diol component having an amide bond, a urethane bond, an ether bond, a carbonate bond or the like may be used.

As a production method of the polyester resin, a so-called direct polymerization method in which terephthalic acid is directly reacted with ethylene glycol (and further dicarboxylic acid and / or other diol if necessary), a dimethyl ester of terephthalic acid and ethylene glycol Such as a dimethyl ester of another dicarboxylic acid and / or other diol according to the method of the present invention, such as the so-called transesterification reaction method. The polyester resin may contain known additives if necessary. Examples of the additives that can be contained include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, photostabilizers, and impact resistance improvers. However, since transparency is required as a protective film laminated on the polarizing film, it is preferable to limit the amount of these additives to a minimum.

By forming the raw resin into a film and subjecting the film to a uniaxial stretching or a biaxial stretching treatment, a protective film comprising a stretched polyester resin can be produced. By conducting the stretching treatment, a film having high mechanical strength can be obtained. The method of producing the stretched polyester resin film is arbitrary and not particularly limited. However, after the raw material resin is melted and the unoriented film extruded into a sheet form is transversely stretched by a tenter at a temperature equal to or higher than the glass transition temperature, And a fixing process is performed.

In the case of using a polyester resin as the protective film, it is preferable that a corona treatment is performed before applying the adhesive, or a polyester resin film having an easy surface adhesion treatment layer is used in order to obtain good adhesion.

The polycarbonate resin used for the protective film is preferably a polyester formed from carbonic acid and glycol or bisphenol. Among them, an aromatic polycarbonate having a diphenylalkane in a molecular chain is preferably used since it has excellent heat resistance, weather resistance and acid resistance. As such polycarbonate, there can be mentioned 2,2-bis (4-hydroxyphenyl) propane (also known as bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, ) Polycarbonates derived from bisphenols such as cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, or 1,1-bis (4-hydroxyphenyl) ethane.

As a method for producing the polycarbonate resin film, any of a flexible film production method, a melt extrusion method, and the like may be used. As a specific example of the production method, a polycarbonate resin is dissolved in an appropriate organic solvent to prepare a polycarbonate resin solution, which is then softened on a metal support to form a web, the web is separated from the metal support, Followed by hot-air drying to obtain a film.

The acrylic resin used for the protective film is not particularly limited, but is preferably a polymer containing methacrylic acid ester as a main monomer, and more preferably a copolymer in which a small amount of another comonomer component is copolymerized. The methacrylic acid ester which is the main component of the acrylic resin is preferably alkyl methacrylate, and methyl methacrylate is particularly preferably used. As the comonomer component, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and the like are generally used. In addition, aromatic vinyl compounds such as styrene and vinyl cyan compounds such as acrylonitrile may be used as comonomer components.

As the production method of the acrylic resin, any usual method such as bulk polymerization, suspension polymerization, emulsion polymerization and the like can be adopted. Particularly, bulk polymerization in which a water-soluble component is not present in the polymerization system is preferably employed. Further, in order to obtain a desired glass transition temperature or to obtain a viscosity showing a moldability to a preferable film, it is preferable to use a chain transfer agent at the time of polymerization. The amount of the chain transfer agent may be appropriately determined depending on the kind and composition of the monomer. The acrylic resin may contain known additives if necessary. Known additives include, for example, lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light stabilizers, impact resistance improvers, surfactants and the like. However, since transparency is required as a protective film laminated on a polarizing film, it is preferable to limit the amount of these additives to a minimum.

As the production method of the acrylic resin film, any method such as the melt-extrusion method such as the melt-softening method, the T-die method and the inflation method, and the calendering method may be used. Among them, a method of melt-extruding a raw material resin from, for example, a T-die and contacting at least one surface of the resulting film with a roll or a belt to form a film is preferable in that a film having good surface properties can be obtained.

The acrylic resin may contain acrylic rubber particles, which are impact modifiers, from the viewpoints of the film composition for the film and the impact resistance of the film. The acrylic rubber particles referred to herein are particles of an elastomer mainly composed of an acrylate ester as an essential component, which have a single-layer structure consisting essentially of only this elastomer, or those having a multi-layer structure composed of this elastomer as a single layer have. As an example of such an elastomer, a crosslinked elastic copolymer comprising an alkyl acrylate as a main component and another vinyl monomer copolymerizable therewith and a crosslinkable monomer is copolymerized. Examples of the alkyl acrylate as a main component of the elastomer include those having an alkyl group of 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, Acrylates having an alkyl group having 4 or more carbon atoms are preferably used. Examples of other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methacrylic acid esters such as methyl methacrylate, The same aromatic vinyl compounds, and vinyl cyan compounds such as acrylonitrile. Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di (meth) acrylate and butanediol di (meth) acrylate (Meth) acrylates of polyhydric alcohols such as allyl (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate, and divinylbenzene.

A laminate of a film made of an acrylic resin not containing rubber particles and a film made of an acrylic resin containing rubber particles may be used as a protective film.

In the case of using an acrylic resin as a protective film, it is possible to obtain good adhesiveness without corona treatment by using the composition of the present invention. However, in order to improve the applicability of the adhesive or to improve the adhesiveness, The corona treatment may be carried out before this step.

The amorphous polyolefin-based resin used for the protective film usually has a polymerization unit derived from an alicyclic olefin such as an alicyclic polyolefin-based resin, that is, norbornene or a derivative thereof, or dimethano-octahydronaphthalene, When a double bond is left, such as a ring-opening polymer, it is preferably a hydrogenated thermoplastic resin. The amorphous polyolefin-based resin may be a copolymer of a cyclic olefin and a chain olefin, or may be introduced with a polar group. Among them, a thermoplastic saturated norbornene resin is typical. Examples of commercially available amorphous polyolefin resins include "ATON" manufactured by JSR Corporation, "ZEONEX" and "ZEONOR" manufactured by Nippon Zeon Co., Ltd., "APO" and "APEL" manufactured by Mitsui Chemicals, Inc. . When an amorphous polyolefin-based resin is formed into a film, known methods such as a solvent casting method and a melt extrusion method are appropriately used for the film formation.

When an amorphous polyolefin-based resin is used as a protective film, it is preferable to conduct corona treatment before applying an adhesive in order to obtain good adhesion.

In the polarizing plate used on the viewing side of the liquid crystal display device, the protective film disposed on the visual side, that is, the opposite side to the liquid crystal cell, can be imparted with antifogging properties. In this case, it is common to form an antiglare layer having surface irregularities on the surface that becomes the visible side of the protective film, that is, the surface opposite to the surface that is adhered to the polarizer. The antiglare layer is generally formed by imparting unevenness to the active energy ray curable resin by an embossing method or by blending fine particles having an index of refraction different from that of the active energy ray curable resin and curing the unevenness. When the protective film is made of an acrylic resin, a laminated film of a light-diffusing layer in which fine particles having a refractive index different from that of the light diffusing agent is mixed in the acrylic resin serving as a binder, and a transparent layer made of an acrylic resin containing no such fine particles, Is also effective. In this case, a laminated film composed of two layers of the above-mentioned light diffusion layer and the above-mentioned transparent layer is laminated to the polarizer on the light diffusion layer side, or a lamination structure of a laminate having a three-layer structure in which both surfaces of the light diffusion layer are sandwiched by the above- And a form in which the film is bonded to the polarizer in one of the transparent layers. Further, by including such a light-diffusing layer, even when an acrylic resin laminated film imparted with a light-shielding property is used as a protective film, it is possible to prevent the surface of the acrylic resin laminate film, It is effective to further improve the anti-glare performance.

As described above, in the case of using an acrylic resin film as a protective film, in the case of the epoxy resin alone which does not contain the aromatic ring shown in the Patent Document 6 (Japanese Patent Laid-Open Publication No. 2004-245925) The composition of the present invention gives good adhesion even when such 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 protective film composed of a transparent resin film selected from the above-described polyester resin, polycarbonate resin, acrylic resin and amorphous polyolefin resin is applied onto at least one surface of the polarizer via the above-described photocurable adhesive . In the case of bonding the protective film to only one side of the polarizer, for example, a pressure-sensitive adhesive layer for bonding to another member such as a liquid crystal cell may be directly formed on the other side of the polarizer.

On the other hand, when the protective film is bonded to both surfaces of the polarizer, the respective protective films may be of the same kind or of different kinds. Concretely, for example, there are a form in which a polyester resin film is applied as a protective film to both surfaces of a polarizer, a form in which a polycarbonate resin is applied as a protective film to both surfaces of the polarizer, a form in which acrylic resin is applied as a protective film to both surfaces of the polarizer, And a transparent resin film selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is applied as a protective film to one surface of the polarizer, and the polarizer The other surface may be selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin, and a transparent resin film different from the one-side protective film may be used as a protective film. Further, a transparent resin film selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is applied as a protective film to one surface of the polarizer, and a polyester resin, a polycarbonate resin, an acrylic resin, Both of the amorphous polyolefin-based resin and the transparent amorphous polyolefin-based resin may be used as a protective film. When the protective film is bonded to both surfaces of the polarizer, the two protective films may be laminated one by one in a stepwise manner, or both surfaces may be laminated in one step.

In the case where a protective film is bonded to both surfaces of a polarizer and one of them is made of another resin film different from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin, as a preferable example of the other resin, Resin. The protective film made of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin which are bonded to one surface of the polarizer is adhered via the above-described photocurable adhesive according to the present invention, May be adhered to each other with another adhesive interposed therebetween. For example, when a protective film made of a resin film having a relatively high moisture permeability such as a cellulose-based resin film is formed on one surface of a polarizer, such a polyvinyl alcohol-based adhesive agent or the like Other adhesives may be used. However, since the photo-curable adhesive according to the present invention gives a high adhesive force to the cellulose-based resin film exemplified here, it is advantageous to use the same adhesive on both sides of the polarizer, since the operation becomes simple.

Examples of the cellulose-based resin which can be used as a protective film for one side include cellulose acetate ester, propionic acid ester, butyric acid ester, and their mixed esters, for example, as partial or complete esterified products of cellulose. Specifically, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, cellulose acetate butyrate and the like can be given. Examples of commercially available films of such a cellulose ester resin include commercially available products such as "Fujitac TD80 "," Fujitac TD80UF "and" Fujitac TD80UZ "manufactured by Fuji Film, KC8UX2M "and" KC8UY ". A cellulose-based resin film imparted with an optical compensation function may also be used. Examples of such an optical compensation film include a film containing a compound having a retardation adjusting function in a cellulose resin, a film coated with a compound having a retardation adjusting function on the surface of the cellulose resin film, a cellulose resin film having a single- A film obtained by biaxial stretching, and the like. Examples of commercially available cellulose-based optical compensation films include "Wide View Film WV BZ 438" and "Wide View Film WV EA" manufactured by Fuji Film Co., Ltd., "KC4FR-1" manufactured by Konica Minolta Opto "And" KC4HR-1 ".

Examples of the transparent resin which is different from the polyester resin, the polycarbonate resin, the acrylic resin and the amorphous polyolefin resin and which can be used as a protective film for one side and has a low moisture permeability include polysulfone resin and alicyclic polyimide resin .

Prior to bonding to the polarizer, the protective film may be subjected to an easy adhesion treatment such as saponification treatment, corona treatment, primer treatment, anchor coating treatment, or the like. The surface of the protective film opposite to the surface to be cohered with the polarizer may have 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 占 퐉, more preferably 10 to 120 占 퐉, and still more preferably 10 to 85 占 퐉.

[Polarizing plate production method]

The polarizing plate of the present invention is characterized in that at least one of the above-described polarizer and the concave surface of a protective film made of a transparent resin film selected from a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin, And a curing step of curing the photo-curable adhesive in a state where the polarizer and the protective film are bonded to each other via the adhesive layer, and a curing step of curing the photo-curable adhesive in a state where the polarizer and the protective film are bonded to each other via the adhesive layer . &Lt; / RTI &gt;

&Lt; Adhesive application step &

In the adhesive applying step, the above-described photocurable adhesive is applied to at least one of the concave surfaces of the polarizer and the protective film. When a photocurable adhesive is directly applied to the surface of the polarizer or the protective film, there is no particular limitation on the coating method. For example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Also, after the above-described photo-curable adhesive is softened between the polarizer and the protective film, a method of pressurizing the film with a roll or the like and uniformly pressing it may be used.

The atmospheric temperature of the adhesive application step is preferably 15 to 30 占 폚, particularly preferably 20 to 25 占 폚. The relative humidity of the application atmosphere is preferably 90% or less, more preferably 80% or less, and further preferably 30 to 80%. By controlling the atmospheric temperature and humidity in the adhesive application step within the above range, the curing property and the adhesive strength can be improved.

<Bonding Step>

After the photocurable adhesive is applied in this way, it is provided in the bonding process. In this bonding step, for example, when a photocurable adhesive is applied to the surface of the polarizer in the previous coating step, a protective film is superimposed thereon, and when the photocurable adhesive is applied to the surface of the protective film in the preceding coating step, Polarizers are superimposed on each other. When the photo-curing adhesive is poured between the polarizer and the protective film, the polarizer and the protective film overlap with each other in this state. When a protective film is applied to both surfaces of a polarizer and both of the surfaces are used with the photocurable adhesive of the present invention, a protective film is superimposed on both surfaces of the polarizer with a photocurable adhesive interposed therebetween. Normally, in this state, a pressure is applied between the rolls and the like from both sides (on the polarizer side and the protective film side when the protective film is superimposed on one side of the polarizer, and on the side of the protective film on both sides of the polarizer when the protective film is superimposed on the polarizer side) . The material of the roll may be metal or rubber. The rolls disposed on both sides may be the same material or different materials.

<Curing Process>

As described above, the state in which the polarizer and the protective film are in contact with each other via the uncured light-curable adhesive is subsequently provided to the curing step. In this curing step, the photo-curable adhesive is irradiated with an active energy ray to cure the adhesive layer containing an epoxy compound, a (meth) acrylate, an oxetane compound or the like to adhere the polarizer and the protective film. When a protective film is bonded to one surface of the polarizer, the active energy ray may be irradiated from either the polarizer side or the protective film side. When a protective film is attached to both surfaces of a polarizer, an active energy ray is irradiated from either side of the protective film side in a state where a protective film is laminated on both surfaces of the polarizer via a photocurable adhesive, It is advantageous to cure at the same time. However, in the case where an ultraviolet absorber is blended in any one of the protective films (for example, a cellulose-based resin film in which an ultraviolet absorber is blended is used as one protective film), when the active energy ray is ultraviolet rays, The ultraviolet ray is irradiated from the side of the protective film to which the ultraviolet absorber of

As the active energy ray, visible light, ultraviolet ray, X-ray, electron beam and the like can be used, but ultraviolet rays are preferably used because they are easy to handle and have a sufficient curing speed. The light source of the active energy ray is not particularly limited, but a light source of a wavelength of 400 nm or less, 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, , An LED lamp, or the like can be used.

The light irradiation intensity with respect to the photocurable adhesive is determined not only by the intended composition but also by a UV-B (medium to long wavelength ultraviolet light of 280 to 320 nm), which is effective for the activation of the polymerization initiator 1 to 3,000 mW / cm &lt; 2 &gt;. When the irradiation intensity is within the above range, the reaction time is adequate, and the yellowing of the photocurable adhesive due to the heat radiated from the lamp and the heat generated during polymerization of the photocurable adhesive can be suppressed.

The light irradiation time for the photocurable adhesive is controlled for each composition to be cured and is not particularly limited, but the total amount of light, which is expressed by the product of irradiation intensity and irradiation time, is set to be 10 to 5,000 mJ / cm 2 by UV-B desirable. When the total amount of light is within the above range, the generation of active species derived from the polymerization initiator is sufficient, the adhesive layer is sufficiently cured, the irradiation time is short, and the productivity is excellent.

In curing the photo-curing adhesive by irradiating the active energy ray, it is preferable to cure the photo-curable adhesive under conditions that do not degrade various functions of the polarizing plate such as the polarization degree, transmittance and hue of the polarizer, and transparency of the protective film.

In the thus obtained polarizing plate, the thickness of the adhesive layer is preferably 50 占 퐉 or less, more preferably 20 占 퐉 or less, further preferably 10 占 퐉 or less, particularly preferably 5 占 퐉 or less.

As a preferable method for further strengthening the adhesive force between the adhesive of the present invention and the protective film, a polarizer and a protective film are laminated using an adhesive, and then, before irradiation of the active energy ray, A heating process may be added. The heating conditions at this time are preferably within a range that does not cause shrinkage of the polarizer or deterioration of optical characteristics. Preferable heating conditions vary depending on the molecular weight of the acrylic resin, and for example, 1 to 10 seconds at 60 DEG C, 5 to 30 seconds at 40 DEG C, and the like. Even if the temperature of the adhesive is cooled to 40 占 폚 or less during heating up to the activation energy ray irradiation, the effect of the improvement of the adhesive strength is not hindered.

Another preferred method for improving the adhesive strength between the adhesive of the present invention and the protective film is to use a polarizing plate having a polarizing plate and a protective film laminated even when the polarizing plate is not heated, that is, at 20 to 25 캜, And the length of time from when the adhesive comes in contact with the acrylic resin to about 60 seconds.

However, the adhesive of the present invention has an advantage of exhibiting a good adhesive force even when the adhesive and the protective film made of acrylic resin come in contact with each other for 20 to 30 seconds at 20 to 25 ° C.

[Optical member]

When the polarizing plate is used, an optical member having optical functions other than the polarization function may be laminated on one side of the polarizing plate. Examples of the optical layer that is laminated on a polarizing plate for the purpose of forming an optical member include various ones used for forming liquid crystal display devices such as a reflection layer, a transflective reflective layer, a light diffusion layer, a retardation plate, a light condensing plate, . The reflective layer, the semi-transmissive reflective layer and the light-diffusing layer are used in the case of forming an optical member made of a polarizing plate of a reflective type, a semi-transmissive type, a diffusive type, or both of them.

The reflection type polarizing plate is used in a liquid crystal display device of the type that reflects incident light from the viewer side and displays the liquid crystal display device, and a light source such as a backlight can be omitted. In addition, the transflective type polarizing plate is used in a liquid crystal display device of the type that displays as a reflection type in a bright place and a light source such as a backlight in a dark place. In the optical member as the reflection type polarizing plate, for example, a reflective layer can be formed by laminating a foil or a vapor deposition film made of a metal such as aluminum on a protective film on a polarizer. The optical member as the transflective type polarizing plate can be formed by making the above-mentioned reflective layer a half mirror, or containing a pearl pigment or the like, and attaching a reflective plate exhibiting light transmittance to the polarizing plate. On the other hand, the optical member as the diffusion-type polarizing plate can be formed by various methods such as a method of applying a matting treatment to a protective film on a polarizing plate, a method of applying a resin containing a fine particle, Thereby forming a micro concavo-convex structure.

The formation of the optical member as the polarizing plate for both of the reflection diffusion and the reflection can be performed by, for example, forming a reflective layer reflecting the concavo-convex structure on the fine uneven structure surface of the polarizing plate. The reflective layer of the micro concavo-convex structure diffuses incident light by diffuse reflection to prevent directivity and glare, and has an advantage of suppressing unevenness of light and shade. The resin layer or film containing fine particles also has an advantage that the incident light and the reflected light thereof are diffused when they penetrate the fine particle-containing layer, whereby the non-uniformity of the light and shade can be further suppressed. The reflective layer in which the surface micro concavo-convex structure is reflected can be formed by laying the metal directly on the surface of the fine concavo-convex structure by vapor deposition such as vacuum deposition, ion plating, sputtering, plating or the like. Examples of the fine particles to be mixed in order to form the surface micro concavo-convex structure include inorganic fine particles made of silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide or the like and having an average particle size of 0.1 to 30 탆, And the like can be used.

On the other hand, the retarder as the above optical layer is used for the purpose of compensating the retardation by the liquid crystal cell or the like. Examples thereof include birefringent films made of stretched films of various plastics, films on which discotic liquid crystals or nematic liquid crystals are aligned and fixed, and those on which the liquid crystal layer is formed on a film substrate. In this case, a cellulose base film such as triacetyl cellulose is preferably used as a film base for supporting the aligned liquid crystal layer.

Examples of the plastic forming the birefringent film include polyolefins such as polycarbonate, polyvinyl alcohol, polystyrene, polymethylmethacrylate and polypropylene, polyarylate, polyamide and amorphous polyolefin resins . The stretched film may be processed in a suitable manner such as a single-axis or a double-axis. It is also possible to use a birefringent film in which the refractive index in the thickness direction of the film is controlled by applying a shrinking force and / or a stretching force under adhesion with the heat-shrinkable film. Further, the retardation plate may be used in combination of two or more for the purpose of controlling optical characteristics such as broadening.

The light-collecting plate is used for the purpose of optical path control or the like, and can be formed as a prism array sheet, a lens array sheet, a dot-laid sheet, or the like.

The brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display device or the like. Examples of the brightness enhancement film include a reflection type linear polarized light separation sheet designed to laminate a plurality of thin film films having different refractive index anisotropies, , An orientation film of cholesteric liquid crystal polymer, and a circularly polarized light separation sheet on which the alignment liquid crystal layer is supported on a film base.

The optical member includes a polarizing plate and a single layer or two or more optical layers selected from the above-mentioned reflective layer or semi-transmissive reflective layer, light diffusing layer, retarder, condenser, A laminate of three or more layers can be formed. In this case, two or more optical layers such as a light-diffusing layer, a retarder, a light-collecting plate, and a brightness enhancement film may be disposed. The arrangement of each optical layer is not particularly limited.

The various optical layers forming the optical member are integrated with the polarizing plate by using an adhesive, but the adhesive used therefor is not particularly limited as long as the adhesive layer can be formed satisfactorily. It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoints of simplicity of the bonding operation and prevention of occurrence of optical deformation. As the pressure-sensitive adhesive, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyether, or the like may be used as the base polymer. Among them, like an acrylic pressure-sensitive adhesive, it has excellent optical transparency, maintains proper wettability and cohesive force, has excellent adhesiveness to a substrate, further has weather resistance and heat resistance, and peels off or peels off under heating or humidification conditions It is preferable to select and use the one that does not cause a problem. In the acrylic pressure-sensitive adhesive, it is preferable to use an alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl group, ethyl group and butyl group and an acrylic monomer containing a functional group comprising (meth) acrylic acid or hydroxyethyl (meth) An acrylic copolymer having a weight-average molecular weight of 100,000 or more, which is obtained by polymerizing and blending such that the glass transition temperature is preferably 25 占 폚 or lower, more preferably 0 占 폚 or lower, is useful as a base polymer.

The pressure-sensitive adhesive layer for the polarizing plate can be formed, for example, by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a liquid having a solid concentration of 10 to 40% by weight, Or a method in which a pressure-sensitive adhesive layer is formed on a separate film in advance and the pressure-sensitive adhesive layer is formed by transferring the pressure-sensitive adhesive layer onto a polarizing plate. The thickness of the pressure-sensitive adhesive layer is determined depending on its adhesive force and the like, but is preferably in the range of about 1 to 50 mu m.

The adhesive layer may contain a filler such as glass fiber, glass beads, resin beads, metal powder or other inorganic powder, a pigment or a colorant, an antioxidant, or an ultraviolet absorber if necessary. Examples of the ultraviolet absorber include a salicylate ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt 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 make a liquid crystal display device. The liquid crystal cell to be used is arbitrary. For example, a 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 or a simple matrix drive type represented by a super twisted nematic type can do. The optical members formed on both sides of the liquid crystal cell may be the same or different.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, the percentages indicating the amounts used or contained are based on weight unless otherwise specified. In addition,% of humidity represents relative humidity at 23 캜. &Quot; Parts &quot; means &quot; parts by weight &quot; unless otherwise specified.

In the examples and comparative examples, the respective components used for preparing the photo-curable adhesive composition are as follows, and are hereinafter referred to as the compound name or each symbol (trade name itself or a part thereof).

Component (A): poly (meth) acrylate compound

HDDA: 1,6-hexanediol diacrylate, "Light Acrylate 1,6HX-A" manufactured by Kyowa Chemical Industry Co., Ltd.

DCPA: tricyclodecane dimethylol diacrylate, "Wright acrylate DCP-A" manufactured by Kyowa Chemical Industry Co., Ltd.

Component (B): polyglycidyl ether compound

HDDGE: 1,6-hexanediol diglycidyl ether, distilled refined product, total chlorine content 0.08%.

Component (C): Oxetane compound

OXT221: bis [(3-ethyloxetan-3-yl) methyl] ether, "Aronoxetane OXT-221" manufactured by TOA Corporation.

(D) Component: A polymer having an epoxy group

Polymer D1: Polymer obtained in Production Example 1 described later.

Polymer D2: Polymer obtained in Production Example 2 described later.

Component (E): Photo cationic polymerization initiator

CPI110P: triarylsulfonium hexafluorophosphate (active ingredient 100%), "CPI-110P" manufactured by San A Pro Co., Ltd.

(F) Component: Photo radical polymerization initiator

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

(G): Leveling agent

SH28: silicone leveling agent "DOW CORNING TORAY SH 28 PAINT ADDITIVE" manufactured by Toor Dow Corning Co., Ltd.

(B) 'Component: An epoxy compound other than the component (B)

JER828: bisphenol A type epoxy resin, "jER-828US" manufactured by Mitsubishi Chemical Corporation.

(D) 'Component: A polymer other than the component (D)

BR87: Methyl methacrylate-based polymer (Mw 25,000, acid value 10.5 mgKOH / g) having no epoxy group, and "Daiyanar BR-87" manufactured by Mitsubishi Rayon.

LA2250: block copolymer (Mw 80,000) of butyl acrylate and methyl methacrylate having no epoxy group, "Kurari LA2250" manufactured by Kuraray Co., Ltd.

Polymer D'1: Polymer obtained in Production Example 3 described later.

Polymer D'2: Polymer obtained in Production Example 4 described later.

Polymer D'3: Polymer obtained in Production Example 5 described later.

[Production Example 1]

The jacket temperature of the 1000 ml capacity pressurized agitation mold reactor equipped with the oil jacket was maintained at 190 占 폚.

Then, methyl methacrylate (hereinafter referred to as "MMA") (45 parts), glycidyl methacrylate (hereinafter referred to as "GMA") (30 parts), styrene (Hereinafter referred to as "St") (25 parts), methyl ethyl ketone (hereinafter referred to as "MEK") (18 parts) as a polymerization solvent, ditertiary butylperoxide ) Was continuously supplied to the reactor from the raw material tank at a constant feed rate (48 g / min, retention time: 12 minutes), and the reaction liquid corresponding to the feed amount of the monomer mixture was fed to the outlet . Immediately after the start of the reaction, a temperature rise due to the polymerization heat was observed once the reaction temperature was lowered. However, by controlling the oil jacket temperature, the internal temperature of the reactor was maintained at 192 to 194 ° C.

The starting point of the reaction solution was taken as the start point of the reaction solution after the temperature in the reactor was stabilized for 36 minutes, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture solution was supplied and 1.2 kg of the reaction solution was recovered.

Thereafter, the reaction solution was introduced into a thin-film evaporator to separate volatile components such as unreacted monomers, and volatile components such as unreacted monomers were removed to obtain polymer &quot; Polymer D1 &quot;.

The polymer D1 thus obtained was measured for GPC, and it was found that the number average molecular weight (hereinafter referred to as "Mn") in terms of polystyrene was 3,500, the Mw (weight average molecular weight) was 9,900, and Tg (DSC measurement, ) Was 65 ° C.

[Production Example 2]

The jacket temperature of the same reactor as in Production Example 1 was maintained at 180 占 폚.

Then, while maintaining the pressure of the reactor at a constant level, MMA (60 parts), GMA (30 parts), Methyl acrylate (10 parts), MEK (18 parts) as a polymerization solvent, and DBP The monomer mixture was continuously fed into the reactor from the raw material tank at the same constant feed rate as in Production Example 1 and the reaction liquid corresponding to the feed amount of the monomer mixture was continuously withdrawn from the outlet. Immediately after the initiation of the reaction, a temperature rise due to polymerization heat was observed once the reaction temperature was lowered. However, by controlling the oil jacket temperature, the internal temperature of the reactor was maintained at 182 to 184 占 폚.

The starting point of the reaction solution was taken as the start point of the reaction solution after the temperature in the reactor was stabilized for 36 minutes, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture solution was supplied and 1.2 kg of the reaction solution was recovered.

Thereafter, the reaction solution was introduced into a thin film evaporator to separate volatile components such as unreacted monomers, and volatile components such as unreacted monomers were removed to obtain polymer &quot; Polymer D2 &quot;.

The obtained polymer D2 was evaluated in the same manner as in Production Example 1, and found that Mn was 3,200, Mw was 8,500, and Tg was 53 占 폚.

[Comparative Production Example 1]

The jacket temperature of the same reactor as in Production Example 1 was maintained at 181 캜.

Subsequently, 45 parts of butyl acrylate (hereinafter referred to as "BA"), 2-ethylhexyl acrylate (45 parts), MMA (10 parts), and isopropyl The monomer mixture consisting of alcohol (9 parts), MEK (9 parts) and DBP (0.25 parts) as a polymerization initiator was continuously supplied to the reactor from the raw material tank at the same constant feed rate as in Production Example 1, Was continuously withdrawn from the outlet. Immediately after the initiation of the reaction, a temperature rise due to polymerization heat was observed once the reaction temperature was lowered. However, by controlling the oil jacket temperature, the internal temperature of the reactor was maintained at 183 to 185 캜. The starting point of the reaction solution was taken as the start point of the reaction solution after the temperature in the reactor was stabilized for 36 minutes, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture solution was supplied and 1.2 kg of the reaction solution was recovered. Thereafter, the reaction solution was introduced into a thin-film evaporator to separate volatile components such as unreacted monomers, and volatile components such as unreacted monomers were removed to obtain polymer "Polymer D'1".

The obtained polymer D'1 was evaluated in the same manner as in Production Example 1, and found that the polymer had Mn of 2,500, Mw of 7,500, Tg of -55 캜 and a viscosity of 20,000 mPa 에 at 25 캜.

[Comparative Production Example 2]

The jacket temperature of the same reactor as in Production Example 1 was maintained at 187 캜.

Subsequently, a monomer mixture composed of BA (50 parts), GMA (50 parts), MEK (18 parts) as a polymerization solvent and DBP (0.25 parts) as a polymerization initiator was added to Production Example 1 Continuous supply to the reactor was started from the raw material tank at the same constant feed rate and the reaction liquid corresponding to the feed amount of the monomer mixture was continuously withdrawn from the outlet. Immediately after the start of the reaction, a temperature rise due to the polymerization heat was observed once the reaction temperature was lowered. However, by controlling the oil jacket temperature, the internal temperature of the reactor was maintained at 189-191 ° C.

The starting point of the reaction solution was taken as the start point of the reaction solution after the temperature in the reactor was stabilized for 36 minutes, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture solution was supplied and 1.2 kg of the reaction solution was recovered.

Thereafter, the reaction solution was introduced into a thin film evaporator to separate volatile components such as unreacted monomers, and volatile components such as unreacted monomers were removed to obtain polymer "polymer D'2".

The polymer D'2 thus obtained was evaluated in the same manner as in Production Example 1, and found that the polymer had Mn of 3,460, Mw of 9,700, Tg of -10 캜 and a viscosity of 12,200 mPa 쨌 s at 80 캜.

[Comparative Production Example 3]

The jacket temperature of the same reactor as in Production Example 1 was maintained at 180 占 폚.

Subsequently, a monomer mixture composed of St (70 parts), GMA (30 parts), MEK (18 parts) as a polymerization solvent and DBP (0.25 parts) as a polymerization initiator was added to Production Example 1 Continuous supply to the reactor was started from the raw material tank at the same constant feed rate and the reaction liquid corresponding to the feed amount of the monomer mixture was continuously withdrawn from the outlet. Immediately after the initiation of the reaction, a temperature rise due to polymerization heat was observed once the reaction temperature was lowered. However, by controlling the oil jacket temperature, the internal temperature of the reactor was maintained at 182 to 184 占 폚.

The starting point of the reaction solution was taken as the start point of the reaction solution after the temperature in the reactor was stabilized for 36 minutes, and the reaction was continued for 25 minutes from this point. As a result, 1.2 kg of the monomer mixture solution was supplied and 1.2 kg of the reaction solution was recovered.

Thereafter, the reaction solution was introduced into a thin-film evaporator to separate volatile components such as unreacted monomers, and volatile components such as unreacted monomers were removed to obtain polymer "Polymer D'3".

The obtained polymer D'3 was evaluated in the same manner as in Production Example 1, and found that Mn was 3,700, Mw was 11,000, and Tg was 65 占 폚.

Examples 1 to 8, Comparative Examples 1 to 8

[Preparation of photocurable adhesive composition]

Each of the components shown in Tables 1 to 4 was blended in respective ratios and stirred and mixed according to a conventional method to prepare a photo-curable adhesive composition.

The viscosity of the obtained composition at 25 캜 was measured by an E-type viscometer manufactured by Toki Kogyo Co.,

[Production of polarizing plate]

Here, the following two types of films were used as protective films.

Drawn norbornene resin film: thickness: 70 占 퐉, trade name: "ZEONOR film", manufactured by Nippon Zeon Co., Ltd. This film was subjected to corona discharge treatment and then provided for bonding with a polarizer.

Acrylic resin film: thickness 80 占 퐉, trade name "Technoloy S001", manufactured by Sumitomo Chemical Co., Ltd. This film was subjected to a corona discharge treatment and then provided for bonding with a polarizer.

On the corona discharge treated surface of the drawn norbornene resin film, the composition prepared above was applied to a thickness of 3 탆 by a bar coater. This coated surface was bonded to a polarizer in which iodine was adsorbed and aligned in polyvinyl alcohol using a hand roller.

Next, on the corona discharge treated surface of the acrylic resin film, the composition prepared above was applied to a thickness of 3 탆 by a bar coater. Thereafter, a polarizer integrated with a norbornene resin film as a liquid composition was applied to a coating surface on an acrylic resin film using a hand roller.

In this way, a polarizer with a protective film adhered on both surfaces thereof was irradiated with ultraviolet rays from a surface of a norbornene resin film at an amount of accumulated light of 250 mJ / cm2 from an ultraviolet irradiator (a lamp was a high-pressure mercury lamp manufactured by Eye Graphics Co., Ltd.) Lt; 2 &gt; (UV-B) to cure the adhesive composition.

This experiment was conducted under the conditions of 23 캜 and 80% relative humidity.

Further, the time until the acrylic resin film was coated with the adhesive composition and irradiated with ultraviolet rays was unified in the range of 20 to 25 seconds.

[Evaluation test]

The polarizing plate after irradiation with ultraviolet rays was subjected to a curing test, a cutter insertion adhesion test, a polarizer bending peel adhesion test at a room temperature storage test (before moisture heat test), a moisture resistance test, a polarizer bending peel adhesion test after a moisture resistance test, And the results are summarized in Tables 1 to 4.

<Curability>

After 15 seconds from ultraviolet irradiation, the acrylic resin film and the polarizer were peeled off by hand, and the degree of curing was judged to be three levels below.

?: Not in a liquid phase, and no bubbles are generated in the film transport process during production.

?: Half liquid, and bubbles may be generated in the film transportation process during production.

X: Liquid phase, bubbles are generated in the film transportation process during production.

&Lt; Cutter insertion adhesion force >

A knife blade of a cutter knife was inserted obliquely from above the acrylic resin film into a polarizing plate which had been exposed to ultraviolet rays for two days or more and judged from the state and strength at that time to the following four levels.

◎: Even if the blade does not fit or the blade is inserted, the resistance is very strong, and the acrylic resin film is directly torn.

○: Although the blade was inserted, the acrylic resin film tore when it tried to widen the peeling due to the strong resistance.

△: The blade is inserted and the resistance is felt, but it is possible to widen the peeling.

X: The blade is inserted, and the resistance is weak enough to allow the blade to proceed with slight force at the interface.

<Polarizer Bending Peel Adhesion of Room Temperature Products (Before Moisture Heat Test)>

The polarizing plate, which had been exposed to ultraviolet rays for 2 days or more, was cut into a single-sided single-sided single-sided, 15-cm wide single-sided desk, and the acrylic resin film side was attached to the glass plate with an adhesive tape. Subsequently, the polarizer film adhered to the upper norbornene resin film was peeled off, and the 180 degree peel test was carried out at a tensile rate of 300 mm / min, and the adhesive force (N / inch) was shown in the table.

&Lt; Heat and humidity test &

A polarizing plate having passed the ultraviolet irradiation for 2 days or more was cut to a width of 4 cm and a length of 6 cm and placed in a high temperature and high humidity environment at 60 캜 and a relative humidity of 90% for 500 hours. The peeling or discoloration of the polarizing plate after the anti-wet heat test was visually observed to determine the following three levels.

○: No peeling or discoloration was observed.

?: Peeling or discoloration was slightly observed.

X: peeling or discoloration was observed.

&Lt; Polarizer Bending Peel Adhesion after Anti-Humid Heat Test >

The polarizing plate, which had been exposed to ultraviolet rays for 2 days or more, was cut into a single-sided single-sided single-sided, 15-cm wide single-sided desk, and the acrylic resin film side was attached to the glass plate with an adhesive tape. This was allowed to stand in a high temperature and high humidity environment at 60 캜 and a relative humidity of 90% for 500 hours and then taken out to an environment at 23 캜 and a relative humidity of 50%. The measurement was carried out by peeling the polarizer film adhered to the upper norbornene resin film and peeling 180 ° at a tensile rate of 300 mm / min. The results (N / inch) are shown in the table.

<Cooling and Heating Cycle Test>

The polarizing plate which had been exposed to ultraviolet rays for two days or more was subjected to a cold / heat shock cycle test in which a cycle of 60 minutes at -35 占 폚 and then 60 minutes at +70 占 폚 was repeated 300 times. The polarizing plate after the cooling / heating cycle test was visually observed to determine the following three levels.

?: No appearance defect was observed.

?: A slight appearance defect was observed.

X: Appearance defect was observed.

The unit of each numerical value of the compounding composition in Tables 1 to 4 is% by weight.

Although the present embodiment is carried out under a high-humidity condition (23 DEG C and 80%) unfavorable to catechin hardening, the compositions of Examples 1 to 8 are excellent in viscosity, curability, cutter insertion adhesive force, polarizer bending peel adhesion strength, Test, the polarizer bending peel adhesion force after the moisture resistance heat test, and the results of the cold / heat cycle test were all good.

Example 2, in which the blending amount of the polymer D1 was 10%, was excellent both in the cutter adhesion and in the peel adhesion as compared with Example 1 in which the blending amount of the polymer D1 was 4%. Example 2 in which Polymer D1 and Polymer D'1 [Polymer not containing monomer (d1) and having a Tg that does not reach the lower limit of Component (D)] were used in Example 2 in which polymer D'1 was not contained 3, the cutter adhesion and the peel adhesion were both excellent.

Example 4, in which the component (A) of Example 3 was slightly reduced and the components (B) and (C) were slightly increased, was more excellent in peel adhesion. In Example 5 in which HDDA and DCPA were used together as the component (A), both the cutter insertion adhesion and the peel adhesion were particularly excellent.

Example 6 in which the polymer D1 of Example 2 was changed to Polymer D2 also exhibited a low viscosity, a curability, a cutter insertion adhesion, a polarizer bending peel adhesion strength at room temperature, an anti-moisture heat test, a polarizer bending peel adhesion strength after anti- The results were all excellent.

On the other hand, Comparative Example 1 in which the polymer D1 of Example 1 was replaced with BR87 (polymer having no epoxy group) and Polymer D1 of Example 2 were changed to polymer D'2 [monomer (d2) The polymer which did not reach the lower limit of the component] was replaced with Comparative Example 2, the cutter insertion adhesion and peel adhesion before and after the anti-wet heat test were insufficient. In Comparative Example 3 in which the polymer D1 of Example 2 was changed to Polymer D'3 (polymer not containing monomer (d2)), the adhesive strength after the moisture heat resistance test was insufficient.

Comparative Example 4 containing no component (A) had poor curability. In Comparative Example 5, which contained the component (A) in excess, the cutter insertion adhesion was poor.

In Comparative Example 6 which did not contain the component (B), all the items were defective, and in Comparative Example 7 in which the component (B) was contained excessively, almost all items were defective.

In Comparative Example 8 containing an excessive amount of the component (C), the peel adhesion was good, but the adhesive force by the cutter insertion method was insufficient.

The photo-curable adhesive composition of the present invention is excellent in curability and adhesion even when it is applied in a thin film at a low viscosity and is applied and cured under high humidity, has excellent adhesive force after completion of the anti-moisture heat test, and has excellent durability , It can be preferably used for the production of a polarizing plate.

Claims (16)

An adhesive composition for adhering a protective film made of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin to a polarizer made of a polyvinyl alcohol based resin film,
(A) a poly (meth) acrylate of a polyol having 2 to 15 carbon atoms,
(B) a polyglycidyl ether of a polyol having 2 to 10 carbon atoms,
(C) a compound having a molecular weight of 500 or less and having at least two oxetanyl groups in one molecule,
(D1) a compound having an epoxy group and an ethylenically unsaturated group, (d2) a hydrocarbon group having 1 to 10 carbon atoms and a compound having one methacryloyl group, and optionally (d3) (d1) ) And (d2), and a polymer having a glass transition temperature of 20 占 폚 or higher and a weight average molecular weight of 1,000 to 30,000, which is obtained by polymerizing these monomers at a high temperature,
(E) a photocathode polymerization initiator,
The content ratio of the components (A) to (E)
Component (A): 5 to 50 wt%
Component (B): 5 to 45 wt%
Component (C): 5 to 45 wt%
Component (D): 1 to 25 wt%
(E): 0.5 to 10 wt%
By weight based on the total weight of the photocurable adhesive composition. The method according to claim 1,
Wherein the component (A) is a di (meth) acrylate of a diol having 2 to 10 carbon atoms. The method according to claim 1,
Wherein the component (B) is a diglycidyl ether of a diol having 2 to 10 carbon atoms other than the polyether diol having 3 or more repeating number of alkylene oxide units. The method according to claim 1,
(C) is an oxetane compound represented by the following formula (1).
[Chemical Formula 1]

The method according to claim 1,
The content of the component (A), the component (B), the component (C), the component (D) and the component (E) is 10 to 45 wt%, 5 to 35 wt%, 5 to 35 wt% 2 to 20% by weight and 2 to 6% by weight. The method according to claim 1,
Wherein the component (D) is a polymer containing 5 to 95% by weight of (d1), 5 to 95% by weight of (d2) and 0 to 80% by weight of (d3) in the total constituent monomer units. The method according to claim 1,
(D) is a polymer containing 0 to 60% by weight of styrene and / or 0 to 40% by weight of a compound having a hydrocarbon group having 1 to 10 carbon atoms and an acryloyl group as (d3) in total constituent monomer units A photocurable adhesive composition. 8. The method of claim 7,
(D3), wherein the component (D) comprises 10 to 60% by weight of glycidyl methacrylate, 10 to 80% by weight of methyl methacrylate as (d2) To 50% by weight, and polymerizing at a high temperature of 160 占 폚 or higher. 8. The method of claim 7,
(D3), and the component (D) comprises 10 to 60% by weight of glycidyl methacrylate, 10 to 80% by weight of methyl methacrylate as (d2) 1 to 30% by weight of a compound having 1 to 10 carbon atoms and 1 acryloyl group, and polymerizing at a temperature of 160 占 폚 or more at a high temperature to obtain a photocurable adhesive composition. The method according to claim 1,
Further, the photocurable adhesive composition containing (F) a photo radical polymerization initiator in a proportion of 10% by weight or less in the composition. The method according to claim 1,
Further, a photocurable adhesive composition containing a leveling agent as a component (G) in an amount of 0.01 to 0.5% by weight in the composition. A polarizing plate comprising a polarizer made of a polyvinyl alcohol based resin film and bonded with a protective film made of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin via an adhesive, Wherein the adhesive is formed from the photo-curable adhesive composition according to any one of claims 1 to 11. A protective film made of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin and an amorphous polyolefin resin is bonded to a polarizer made of a polyvinyl alcohol based resin film through an adhesive to produce a polarizing plate As a method,
An adhesive applying step of applying the photo-curable adhesive composition according to any one of claims 1 to 11 to at least one of the laminated surfaces of the polarizer and the protective film;
An adhesion step of bonding the polarizer and the protective film through the obtained adhesive layer,
And a curing step of curing the photo-curable adhesive composition in a state where the polarizer and the protective film are bonded to each other via the adhesive layer. An optical member characterized in that another optical layer is laminated on the polarizing plate according to claim 12. 15. The method of claim 14,
And the other optical layer comprises a retarder. The liquid crystal display device according to claim 14, wherein the optical member is disposed on one side or both sides of the liquid crystal cell.