KR20160007350A - Adhesive for polarizing plate, and display device using the same - Google Patents

Abstract

Embodiments of the Invention Polarizers; An adhesive layer formed on the surface of the polarizer; And a protective film pasted on at least one side of the polarizer via the adhesive layer; Wherein the adhesive layer comprises a cured product of a resin composition containing an epoxy resin having an isosorbide structure. As a result, the embodiments of the present invention can provide a polarizing plate which is excellent in adhesiveness to a polarizer and a protective film, has excellent heat resistance, can prevent cracks from occurring in the polarizer, and a display device including such a polarizing plate .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adhesive for a polarizing plate,

The present invention relates to an adhesive for a polarizing plate and a display device using the same.

BACKGROUND ART As a recent image display apparatus, flat panel displays such as a liquid crystal display and a plasma display are widely used. Such a flat panel display can save space and realize a high image quality. Of these, the liquid crystal display has excellent power consumption efficiency and can realize a higher quality image, and therefore, many developments are underway.

In a panel of a liquid crystal display, a polarizing plate serving as an optical shutter is used in combination with a liquid crystal. Such a polarizing plate includes a polarizer. Since a conventional polarizer is produced by uniaxially stretching a polyvinyl alcohol resin to a length of 5 to 6 times in a water bath, it is easily split in the stretching direction and has drawbacks. Therefore, the polarizer is configured to adhere the protective film to both surfaces.

As the adhesive for bonding the polarizer to the protective film, a polyvinyl alcohol-based water-based adhesive may be used. However, the polyvinyl alcohol-based water-based adhesive has a problem that it is difficult to adhere to a film formed by, for example, a cycloolefin polymer, and the productivity is low.

In order to solve such a problem, Japanese Patent Application Publication (JP4306270B) discloses an adhesive composed of a composition containing an epoxy resin not containing an aromatic ring as a main component and containing a photo cationic polymerization initiator.

Patent Document 2 (JP2008-257199A) discloses an epoxy resin having two or more epoxy groups in a molecule and at least one of the epoxy groups being an alicyclic epoxy group, an epoxy resin having two or more epoxy groups in the molecule and substantially free of an alicyclic epoxy group A photo-curable adhesive containing a resin and a photo cationic polymerization initiator has been proposed.

However, the adhesives described in the above Patent Documents 1 and 2 have a problem in that it is difficult to make both polarizers and protective films compatible with each other, and heat resistance is poor, so that cracks tend to occur in the polarizer.

JP 4306270 B JP 2008-257199 A

It is an object of the present invention to provide an adhesive for a polarizing plate which is excellent in both the polarizer and the protective film both in adhesiveness and heat resistance.

Another object of the present invention is to provide an adhesive for a polarizing plate capable of suppressing cracking of a polarizer and a display device using the same.

An embodiment of the present invention is a polarizer comprising: a polarizer; An adhesive layer formed on the surface of the polarizer; And a protective film pasted on at least one side of the polarizer via the adhesive layer; Wherein the adhesive layer comprises a cured product of a resin composition containing an epoxy resin having an isosorbide structure.

Another embodiment of the present invention relates to a display device provided with a polarizer according to the above-described embodiments.

Embodiments of the present invention can provide an adhesive for a polarizing plate and a display device using the same, which are excellent in adhesion to both the polarizer and the protective film, excellent in heat resistance, and capable of suppressing cracking of the polarizer.

1 is a cross-sectional view illustrating a polarizer according to an embodiment of the present invention.
2 is a view for explaining a polarizing plate manufacturing method according to an embodiment of the present invention.
3 is a view for explaining an initial curability test of a polarizing plate according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a cross-sectional view illustrating a polarizer according to an embodiment of the present invention.

As shown in Fig. 1, the polarizing plate 1 of the embodiment is provided on both surfaces of the polarizer 2 via the polarizer 2, the adhesive layer 9 formed on the surface of the polarizer 2, and the adhesive layer 9, (Hereinafter also simply referred to as " protective film ") 3. The adhesive layer 9 comprises a cured product of a resin composition containing an epoxy resin having an isosorbide structure.

<Polarizer>

The polarizer 2 is not particularly limited, and conventionally known ones can be used. For example, the polarizer may include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially-foamed polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymerized partial saponification film. In another example, the polarizer may be a polyene oriented film such as a dehydrated product of polyvinyl alcohol or dehydrochlorinated product of polyvinyl chloride.

More specifically, the polarizer can be used after being stretched after adsorbing a dichroic material (for example, iodine or a dichroic raw material) to the polymer film.

Specifically, the polarizer may be a polyvinyl alcohol film having an average polymerization degree of 2,000 to 2,800 and a degree of saponification of 90 to 100% by mole. At this time, the polyvinyl alcohol film can be obtained by immersing it in an aqueous iodine solution for dyeing and then uniaxially stretching it 5 to 6 times. The iodine aqueous solution may be, for example, an aqueous solution containing 0.1% by weight to 1.0% by weight of solids of iodine-potassium iodide. In another embodiment, the polarizer can be immersed in an aqueous solution such as boric acid or potassium iodide at 50 ° C to 70 ° C. The polarizer may be immersed in water at 25 占 폚 to 35 占 폚 in order to prevent washing or staining.

The order of stretching the polarizer is not limited, and may be performed after dyeing, during dyeing or before dyeing. The polarizer can be washed with water after dyeing and stretching, and dried at 35 ° C to 55 ° C for 1 minute to 10 minutes.

<Protection film>

The protective film (3) can be made of a material having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like. Protective films for polarizers include, for example, cellulosic resins such as cellulose diacetate, cellulose triacetate, cellulose tripropionate, and cellulose dipropionate; Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate; (Meth) acrylic resins such as polymethyl methacrylate; Styrene-based resins such as polystyrene, acrylonitrile-styrene copolymer (AS resin); Polycarbonate resin; Polyolefin resins such as polyolefins having polyethylene, polypropylene, cyclic or norbornene structures, ethylene / propylene copolymers and cycloolefins; Vinyl chloride resin; Amide resins such as nylon and aromatic polyamide; Imide resin; Sulfonic resin, polyether sulfone resin; Polyetheretherketone (PEEK) resins; Polyphenylene sulfide type resin; Vinyl alcohol-based resin; Vinylidene chloride resins; Vinyl butyral resin; Arylate resins; Polyoxymethylene type resin; Epoxy resin; Or a mixture of the resins, and the like.

In an embodiment, the protective film 3 may use at least one of cellulose triacetate (TAC film), cycloolefin polymer (COP film) and polyethylene terephthalate (PET film). In this case, the material is easily available and the cost efficiency is excellent.

In one embodiment, the cycloolefin polymer (COP) is exemplified by a polymer obtained by hydrogenating a ring-opening polymer of tetracyclododecene disclosed in Japanese Patent Publication No. 2-9619. As commercial products of the cycloolefin polymer (COP) film, ARTON (registered trademark) of JSR Corporation, ZEONEX (registered trademark) series of NIHON ZEON Co., Ltd., ZEONOR, (Registered trademark) series.

In another embodiment, as a commercially available product of polyethylene terephthalate (PET) film, COSMOSHINE (registered trademark) series manufactured by TOYO BOSEKI CO., LTD. Is exemplified.

In yet another embodiment, the cellulose triacetate (TAC) can be saponified, but the use of un-saponified cellulose triacetate (TAC) can further improve the cost efficiency of the manufacturing process. Examples of commercial products of cellulose triacetate (TAC) films include UV-50, UV-80, SH-80, TD-80U, TD-TAC, UZ-TAC, KC series of products manufactured by Konica Minolta Opto Co., For example.

The surface of the protective film 3 can be modified by a corona discharge treatment. As a result, active groups such as, for example, hydroxyl groups are formed on the surface of the protective film 3, which is believed to contribute to further improvement in adhesiveness. The corona discharge treatment method is not particularly limited, and can be performed using a general corona discharge treatment apparatus (for example, KASUGA ELECTRIC WORKS LTD.).

In one embodiment, when the saponified cellulose triacetate is used as the protective film 3, the same effect as the corona discharge treatment can be expected to improve the adhesiveness, so that the corona discharge treatment is not necessarily required. In another embodiment, when the un-saponified cellulose triacetate is subjected to corona discharge treatment, the complicated and expensive saponification process can be omitted. In this case, the cost efficiency of the manufacturing process can be more excellent.

The amount of discharge at the time of corona treatment is not particularly limited and may be, for example, 30 W.min / .mu.m to 300 W.min / .mu.m, and 50 W.min / .mu.m to 250 W.min./m2. Within this range, the adhesiveness between the protective film 3 and the adhesive layer 9 can be improved without deteriorating the protective film 3 itself. Here, the discharge amount means a work amount to the object by the corona discharge represented by the following formula (1). The corona discharge power can be determined based on the discharge amount.

[Formula 1]

(Discharge amount) = [(discharge electric power) / {(object processing speed) x (electrode length)}]

<Adhesive Layer>

The adhesive layer 9 includes a cured product of a resin composition containing an epoxy resin having an isosolide structure. In this case, the adhesive layer is excellent in adhesiveness, has excellent heat resistance, and can suppress cracking of the polarizer 2 in a thermal shock test such as a cooling and heating cycle.

The adhesive layer of one embodiment may have a peel strength of 4 N / 25 mm to 8.5 N / 25 mm for the PET film and a peel strength of 1.7 N / 25 mm to 3.5 N / 25 mm for the COP film. In this case, the adhesive layer is not only excellent in adhesiveness but also can further improve the endurance reliability of the polarizing plate.

In embodiments, the adhesive layer may have a peel strength of 4 N / 25 mm to 8.5 N / 25 mm, 4.5 N / 25 mm to 8.0 N / 25 mm, 4.8 N / 25 mm to 8.0 N / 25 mm, 5 N / 7.5 N / 25 mm or 5 N / 25 mm to 7.0 N / 25 mm.

In embodiments, the adhesive layer may have a peel strength for the COP film of 1.7 N / 25 mm to 3.5 N / 25 mm, 1.8 N / 25 mm to 3.0 N / 25 mm, or 2.0 N / 25 mm to 3.0 N / 25 mm.

In one embodiment, the adhesive layer may have a ratio of peel strength to PET film (peel strength to PET film / peel strength to COP film) to peel strength to the COP film of 1 to 5 times. In this case, the adhesive layer is not only excellent in adhesiveness but also can further improve the endurance reliability of the polarizing plate.

In embodiments, the ratio of the peel strength may be from 2 to 3.5, from 2.3 to 3.25, from 2.6 to 3.25, or from 2.8 to 3.25. In this case, the adhesive layer is not only excellent in adhesiveness but also can further improve the endurance reliability of the polarizing plate.

The adhesive layer in one embodiment can be formed by applying a resin composition for forming an adhesive layer containing an epoxy resin having an isosolide structure to the surface of a polarizer and then curing the resin composition. In this case, the adhesive layer is excellent in adhesiveness, has excellent heat resistance, and can suppress cracking of the polarizer 2 in a thermal shock test such as a cooling and heating cycle.

In addition to the epoxy resin having an isosolide structure, the resin composition for forming an adhesive layer in one embodiment may contain an aromatic epoxy resin; An epoxy resin having no aromatic skeleton; At least one of a photoacid generator or a photosensitizer; And (meth) acrylic resins; Or more.

The resin composition for forming an adhesive layer in one embodiment is an epoxy resin having an isosolide structure; An epoxy resin having no aromatic skeleton; And a photoacid generator; . &Lt; / RTI &gt;

In another embodiment, the resin composition for forming an adhesive layer comprises an epoxy resin having an isosolide structure; Aromatic epoxy resins; An epoxy resin having no aromatic skeleton; And photoacid generators and photosensitizers; . &Lt; / RTI &gt;

In another embodiment, the resin composition for forming an adhesive layer comprises an epoxy resin having an isosolide structure; An epoxy resin having no aromatic skeleton; Photoacid generators and photosensitizers; And (meth) acrylic resins; . &Lt; / RTI &gt;

In another embodiment, the resin composition for forming an adhesive layer comprises an epoxy resin having an isosolide structure; Aromatic epoxy resins; An epoxy resin having no aromatic skeleton; Photoacid generators and photosensitizers; And (meth) acrylic resins; . &Lt; / RTI &gt;

Hereinafter, the components included in the resin composition for forming an adhesive layer (hereinafter referred to as &quot; resin composition &quot;) according to the embodiments of the present invention will be described in detail.

Epoxy resin with isosolide structure

The resin composition of one embodiment includes an epoxy resin having an isosolide structure.

Specifically, an epoxy resin having an isosolide structure may include an epoxy resin having two glycidyl groups in the molecule.

More specifically, the epoxy resin having an isosolide structure and having two glycidyl groups in the molecule may be a compound represented by the following formula (1)

[Chemical Formula 1]

.

When the compound of Chemical Formula 1 is used as an epoxy resin having an isosolide structure, occurrence of cracks in the polarizer in the thermal shock test such as a cooling and heating cycle can be further suppressed.

The content of the epoxy resin having an isosolide structure may be 5 wt% to 60 wt%, for example, 5 wt% to 55 wt% or 10 wt% to 50 wt% with respect to the whole resin composition. Within the above range, the resin composition can improve the reliability and adhesion of the adhesive layer.

The resin composition of one embodiment may further include at least one of an aromatic epoxy resin and an epoxy resin having no aromatic skeleton.

Aromatic epoxy resin

The resin composition of one embodiment may further include an aromatic epoxy resin

Specifically, the aromatic epoxy resin may include at least one of bisphenol A type diglycidyl ether, bisphenol F type diglycidyl ether and resorcinol type diglycidyl ether. In this case, the resin composition can further improve the adhesiveness of the adhesive layer.

The bisphenol A type epoxy resin may be synthesized directly, or a commercially available product may be used. Commercially available bisphenol A type epoxy resins are commercially available, for example, from EPIKOTE (registered trademark) 825, 828, 834, 1001, 1002, 1003, 1004, 1007, 1009, 1010 YD-019, YD-019, YD-022 (manufactured by TOHTO KASEI), EPICLON (registered trademark) 840 , 850, 1050, 3050, HM-101, and EXA850CRP (manufactured by DIC Co., Ltd.).

In another embodiment, the aromatic epoxy resin is selected from the group consisting of glycidyl ethers of phenol novolac resins, glycidyl etherates of cresol novolak resins, glycidyl etherates of phenol aralkyl resins, glycidyl ether of naphthol aralkyl resins, Diallyl phthalate, diallyl phthalate, diallyl phthalate, diallyl phthalate, diallyl phthalate, diallyl phthalate, diester phthalate, and glycidyl ether phthalate of phenol dicyclopentadiene resin. In this case, the resin composition can further improve the adhesiveness of the adhesive layer.

The content of the aromatic epoxy resin may be 0 wt% to 40 wt%, for example, 5 wt% to 40 wt%, 8 wt% to 30 wt%, or 10 wt% to 30 wt% . Within the above range, the resin composition can further improve the reliability and adhesion of the adhesive layer.

The aromatic epoxy resin may be contained in an amount of 0.1 to 4 times the weight of the epoxy resin having the above-described isosolide structure. Specifically, the weight ratio of the epoxy resin: aromatic epoxy resin having an isosolide structure is 1: 0.1 to 1: 4, 1: 0.1 to 1: 3, 1: 0.4 to 1: 3, 1: 0.4 to 1: 1: 0.5 to 1: 1.3. Within the above range, the resin composition can further improve the reliability and adhesion of the adhesive layer.

In one embodiment, the content of the aromatic epoxy resin in the resin composition may be larger than the content of the epoxy resin having the structure of the isosorbide. In this case, the resin composition can further improve the reliability and adhesion of the adhesive layer.

In another embodiment, the resin composition may have a content of aromatic epoxy resin less than the content of epoxy resin having the structure of isosorbide. In this case, the resin composition can further improve the adhesive force between the adhesive layer and the PET.

Epoxy resin without aromatic skeleton

The resin composition of one embodiment may further include an epoxy resin having no aromatic skeleton. In such a case, the resin composition is improved in photoreactivity and easily controlled in viscosity.

The epoxy resin not having an aromatic skeleton may include, for example, an aliphatic epoxy resin, an alicyclic epoxy resin, or a mixture thereof.

Specifically, the aliphatic epoxy resin may include an aliphatic polyhydric alcohol or a polyglycidylether compound of an alkylene oxide adduct thereof. For example, the aliphatic epoxy resin may be 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, trimethyl Propylene glycol diglycidyl ether, propylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycerol, Lysyldiethers, trimethylolpropane diglycidyl ethers, polyethylene glycol diglycidyl ethers, and the like.

Specifically, the alicyclic epoxy resin includes, for example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1,2: 8,9-diepoxy limonene, 1,2- -Vinylcyclohexane, and the like.

In an embodiment, as the epoxy resin having no aromatic skeleton, for example, an epoxy resin containing an acrylate group such as 3,4-epoxycyclohexylmethyl methacrylate can be used. In this case, the resin composition can have improved photoreactivity and more easily control the viscosity.

The content of the epoxy resin not having an aromatic skeleton is preferably from 15% by weight to 80% by weight, for example, from 20% by weight to 80% by weight, from 20% by weight to 75% by weight, 20% to 65% by weight. Within the above range, the resin composition can improve the curing degree and flexibility of the adhesive layer.

The epoxy resin not having an aromatic skeleton may be contained in an amount of 0.5 to 6 times the weight of the epoxy resin having the above-described isosolide structure. Specifically, the weight ratio of the epoxy resin having an isosolide structure to the epoxy resin having no aromatic skeleton is 1: 0.5 to 1: 6, 1: 0.5 to 1: 4.7, 1: 0.5 to 1: 2.6, 1: 1.5. Within the above range, the resin composition can further improve the reliability and adhesion of the adhesive layer and can further improve the adhesion to the COP film and the PET film.

In one embodiment, the resin composition comprises an epoxy resin having an isosolide structure; Aromatic epoxy resins; And an epoxy resin having no aromatic skeleton.

In this case, the weight ratio of the aromatic epoxy resin having no aromatic skeleton included in the resin composition is, for example, 1: 1 to 1: 7.5, 1: 1 to 1: 3.5, or 1: . Within the above range, the resin composition can further improve the adhesion to the COP film and the PET film.

In this case, the weight ratio of the epoxy resin: aromatic epoxy resin: having an isosolide structure contained in the resin composition and the epoxy resin having no aromatic skeleton may be 1: 0.5 to 6: 0.5 to 42. Within the above range, the resin composition can further improve the adhesion to the COP film and the PET film.

Photoacid generators and / or photosensitizers

The resin composition may include at least one of a photo acid generator (photopolymerization initiator) and a photosensitizer. In such a case, the resin composition may have improved mechanical strength and adhesiveness after curing. As the photoacid generator, conventionally known photoacid generators may be used without particular limitation. Specifically, it may include, for example, an aromatic salt such as an aromatic diazonium salt, an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt, an iron-allene complex, and the like. These may be used alone or in combination of two or more kinds.

The aromatic diazonium salt may include, for example, benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, benzene diazonium hexafluoroborate and the like.

Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diester 4 -Nonylphenyl) iodonium hexafluorophosphate, and the like.

Examples of the aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenyl Thio) phenyl] sulfonium hexafluoroantimonate, 4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate, 4,4'-bis [di ((β-hydroxyethoxy ) Phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate, 7- [ Di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p- (Pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfo-diphenylsulfate (P-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p-tert- butylphenylcarbonyl) (P-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium, and the like.

Examples of the iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadiene (II) -tris (trifluoromethylsulfonyl) methanide, and the like.

Commercial products of the photo acid generators may be commercially available, for example, CPI-100P, 101A, 200K, 210S (manufactured by San A Pro Co.), KAYARAD (registered trademark) PCI-220, (Manufactured by Nippon Kayaku), UVI-6990 (manufactured by Union Carbide), Adeka Optoma SP-150 and SP-170 (manufactured by Adeka Corporation), CI-5102, 101, 102, 103, 105, MPI-103, 105, BBI-101, 102, 103, 105, TPS-101, 102, 103, 105, MDS-103, 105, DTS-102 and 103 (manufactured by Midori-kagaku) and PI-2074 (manufactured by Rhodia Japan KK).

The content of the photoacid generator may be 0.1 wt% to 10 wt%, specifically 0.5 wt% to 8 wt%, more specifically 1 wt% to 5 wt% with respect to the whole resin composition. Within the above range, the resin composition can be improved in curability after irradiation with energy rays, and the durability of the adhesive layer formed after curing can be improved.

As the photosensitizer, conventionally known photoacid generators may be used without particular limitation. When the resin composition contains a photosensitizer, the reactivity of the cationic polymerization can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, halogen compounds and light reducing pigments, and more specifically, benzoin methyl Benzoin derivatives such as ether, benzoin isopropyl ether, and?,? -Dimethoxy-? -Phenylacetophenone; Benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone and 4,4'-bis (diethylamino) ; Thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloro anthraquinone and 2-methyl anthraquinone; Acridone derivatives such as N-methyl acridone and N-bithylacridone; And?,? - diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compound, halogen compound and the like.

The content of the photosensitizer may be 0 wt% to 5 wt%, specifically 0 wt% to 3 wt%, more specifically 0 wt% to 2 wt% with respect to the whole resin composition. Within the above range, the resin composition can be improved in curability after irradiation with energy rays, and the durability of the adhesive layer formed after curing can be further improved.

(Meth) acrylic resin

The resin composition of one embodiment may further contain a (meth) acrylic resin. When a (meth) acrylic resin which is a radical polymerizable compound is contained, the resin composition further improves the photoreactivity and easily controls the viscosity.

As the (meth) acrylic resin, conventionally known ones can be used without particular limitation, as long as they exhibit radical polymerization. The (meth) acrylic resin may be contained in a state in which (meth) acrylic monomers are polymerized to form a resin or in a state of a (meth) acrylic monomer.

For example, the (meth) acrylic monomer may include a monomer having a (meth) acryloyl group, a (meth) acrylamide group and the like, and may include (meth) acrylic acid and its derivatives, (meth) acrylonitrile, (Meth) acrylamide and derivatives thereof, and the like. These monomers may be used alone or in combination of two or more.

More specifically, (meth) acrylic monomers include (meth) acrylic acid and salts thereof. The (meth) acrylic monomer may be, for example, methyl (meth) acrylate, ethyl (meth) acrylate, methylphenoxyethyl (meth) acrylate, n- (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, cyclohexyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2-hydroxy-3 - phenoxypropyl (meth) acrylate, ethylene glycol di (Meth) acrylate, phenoxyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, phenoxy diethylene glycol (meth) acrylate, triethylene glycol di (Meth) acrylate, phenoxy triethylene glycol di (meth) acrylate, butyleneglycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, polypropylene glycol di (Meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol (meth) acrylate, dipropylene glycol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri )acryl (Meth) acrylate, isobornyl (meth) acrylate, N-vinylpyrrolidone, acryloylsulfone, urethane (meth) acrylate, tetrahydrofurfuryl (Meth) acrylate of a mono? -Caprolactone adduct of tetrahydrofurfuryl alcohol, a (meth) acrylate of a di-e-caprolactone adduct of tetrahydrofurfuryl alcohol, a mono? -Methyl- (meth) acrylate of 隆 -valerolactone adduct, a (meth) acrylate of 隆 -methyl-隆 -valerolactone adduct of tetrahydrofurfuryl alcohol, ω-carboxy-polycaprolactone monoacrylate Metha) acrylic ester compounds; Nitrile group-containing vinyl compounds such as acrylonitrile and methacrylonitrile; (Meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl Containing vinyl compounds such as N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, diacetone (meth) acrylamide and N, N-methylenebis can do.

In an embodiment, the resin composition may include at least one of a hydroxyl group-containing (meth) acrylic monomer and a phenoxy group-containing (meth) acrylic monomer as the (meth) acrylic resin.

(Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, methylphenoxyethyl -Hydroxy-3-phenoxypropyl acrylate. &Lt; / RTI &gt; In this case, the resin composition is excellent in initial curability and the ability to bond the polarizer and the protective film can be improved.

The content of the (meth) acrylic resin is 0 wt% to 50 wt%, 0 wt% to 50 wt%, specifically 5 wt% to 30 wt%, more specifically 10 wt% to 20 wt% % &Lt; / RTI &gt; Within the above range, the resin composition can be improved in curability after irradiation with energy rays, and the durability of the adhesive layer formed after curing can be further improved.

In one embodiment, the (meth) acrylic resin may be contained in the resin composition for forming an adhesive layer in the state of the monomer described above.

In another embodiment, the (meth) acrylic resin may be contained in the resin composition for forming an adhesive layer in a state in which the above-mentioned monomers are polymerized.

The (meth) acrylic resin may be contained 0.3 to 1 times the weight of the epoxy resin having the above-described isosolide structure. Specifically, the weight ratio of the epoxy resin: (meth) acrylic resin having an isosolide structure is 1: 0.3 to 1: 1, 1: 0.4 to 1: 1, 1: 0.4 to 1: 0.8, 0.8. Within the above range, the resin composition can further improve the reliability and adhesion of the adhesive layer and can further improve the adhesion to the COP film and the PET film.

In one embodiment, the resin composition comprises an epoxy resin having an isosolide structure; An epoxy resin having no aromatic skeleton and (meth) acrylic resin. In this case, the weight ratio of the epoxy resin: (meth) acrylic resin having no aromatic skeleton contained in the resin composition may be 1: 0.3 to 1: 1, or 1: 0.4 to 1: 1. Within the above range, the resin composition can further improve the adhesion to the COP film and the PET film.

&Lt; Polarizing plate production method >

Method for producing resin composition of adhesive layer

The method for producing the resin composition for forming an adhesive layer of the present invention is not particularly limited.

In specific embodiments, the resin composition for forming an adhesive layer comprises an epoxy resin having the above-described isosolide structure; And at least one of an aromatic epoxy resin, an epoxy resin having no aromatic skeleton, a photoacid generator, a photosensitizer, a (meth) acrylic monomer, and a (meth) acrylic resin.

In addition, the resin composition may further contain an organic solvent for viscosity adjustment. There is no particular limitation on the mixing method, and for example, it may be a method of thoroughly stirring and mixing at room temperature (25 캜) until the mixture becomes uniform.

Method for producing polarizer

Hereinafter, a polarizing plate manufacturing method of one embodiment of the present invention will be described with reference to FIG. As shown in Fig. 2, in the polarizing plate manufacturing method of one embodiment, the protective film 3 located on both surfaces of the polarizer 2 is bonded by using the resin composition 6 for forming an adhesive layer described above. Specifically, a polarizer 2 is sandwiched between two protective films 3, and an appropriate amount of a resin composition 6 for an adhesive layer is dropped between the protective film 3 and the polarizer 2 by a dropper &Lt; / RTI &gt; Thereafter, the polarizer 2 and the protective film 3 are adhered to each other by the roll presses 7 and 8, whereby the polarizing plate 10 can be manufactured.

Then, the polarizing plate 10 attached to each other in the above-described exemplary method is irradiated with light having a wavelength of 300 mJ / cm2 to 3000 mJ / cm2, specifically 500 mJ / cm2 to 2000 mJ / cm2, more specifically 800 mJ / The polarizing plate 1 including the cured product of the resin composition is produced as shown in Fig. 1 by irradiating ultraviolet rays of 1500 mJ / cm 2 (365 nm standard, using a metal halide lamp) at both sides.

1 and 2, only the example in which the adhesive layer 9 is formed on both sides of the polarizer 2 and the polarizer 2 is sandwiched between the two protective films 3 has been described. However, The adhesive layer 9 may be formed only on one side of the polarizer 2 by way of examples.

The resin composition can be applied so that the thickness of the cured adhesive layer 9 is 20 占 퐉 or less, specifically 10 占 퐉 or less, more specifically, 5 占 퐉 or less. Within this range, the adhesive layer can improve the reliability and flexibility of the polarizing plate.

Example

Hereinafter, the present invention will be described based on embodiments, but the present invention is not limited to these embodiments. Further, it is to be understood that the present invention is not limited to the above-described embodiments, and various modifications and changes may be made without departing from the scope of the present invention.

Example 1

<Preparation of Resin Composition for Adhesive Layer>

10 parts by weight of an isosorbide diglycidyl ether resin (ISK-DPE, product of Yokkaichi Chemical Company, product name: ISB-DPE), which is an epoxy resin having an isosolide structure, bisphenol A type epoxy resin ), 30 parts by weight of an epoxy resin (product name: EXA-850CRP), 60 parts by weight of an aliphatic epoxy resin (Neopentylglycoldiglycidylether, trade name: NP-E, product of Yokkaichikase Co., And 1 part by weight of a photosensitizer (trade name: DETX-S, product name: manufactured by Nippon Kayaku Co., Ltd.) in a room temperature (25 ° C) The mixture was stirred and mixed until uniform, to obtain a resin composition for an adhesive layer. The material used and the blending ratio thereof are shown in Table 1 below.

<Production of Polarizer>

The polarizer was produced by the following method. A polyvinyl alcohol film having an average degree of polymerization of 2400 and a degree of saponification of 99.9% and a thickness of 75 占 퐉 was swollen by swelling in hot water at 28 占 폚 for 90 seconds and then an aqueous solution of 0.6% by weight of iodine / potassium iodide (weight ratio 2/3) , And the polyvinyl alcohol film was dyed while being stretched 2.1 times. Thereafter, stretching was carried out in an aqueous boric acid ester solution at 60 占 폚 so that the total draw ratio was 5.8 times, followed by washing with water and drying at 45 占 폚 for 3 minutes to prepare a polarizer (thickness 25 占 퐉).

&Lt; Production of polarizing plate &

Using the polarizer and the resin composition thus prepared, a polarizing plate was produced in a thermostatic chamber at room temperature (25 DEG C) and a humidity of 50% RH. A PET film (Toyoboseki Co., Ltd., trade name: Cosmo Shine A4300, thickness: 100 占 퐉) and a COP film (made by Nippon Zeon Co., thickness: 50 占 퐉) were used as the protective film.

The resin composition prepared above was dropped between a polarizer and a protective film using a syringe, and a roll press polarizer and a protective film were adhered to each other to prepare a polarizing plate before ultraviolet irradiation. The polarizing plate before ultraviolet ray irradiation was irradiated with ultraviolet rays at 1000 mJ / cm 2 (365 nm standard, using a metal halide lamp) on both sides. Thereafter, the polarizing plate immediately after ultraviolet irradiation was kept in the above-described constant temperature room for 24 hours, and the resin composition was aged and cured, thereby completing the polarizing plate. The thickness of one side of the adhesive layer formed after curing was 2 탆 to 3 탆.

<Initial Curability Test>

As shown in Fig. 3, the polarizing plate immediately after the ultraviolet irradiation was folded so that the interval between the polarizing plates 1 was 10 mm (R10 mm), and whether or not the protective film was peeled off was visually judged. When no peeling was observed, it was indicated as &amp; cir &amp; The above results are shown in Tables 1 to 3.

&Lt; Peel strength test &

The prepared polarizing plate was fixed to the SUS plate with double-sided tape. Next, a knife was inserted into the end face of the polarizing plate so as to be peeled off from the interface (i.e., adhesive layer) between the polarizer of the polarizing plate and the protective film, and a peeled portion was formed. Then, the peeled portion was peeled toward the direction of 90 DEG C at a predetermined peel rate (300 mm / min), and the peel strength of the PET film and the COP film as protective films were measured. The above results are shown in Tables 1 to 3.

<Test of Foundation>

The prepared polarizing plate was cut with a Thomson knife to a size of 50 mm x 50 mm and the state of peeling at the end of cutting was visually observed. As an evaluation standard, 0.5 mm or less was passed. The above results are shown in Tables 1 to 3.

<Hot water immersion test>

The prepared polarizing plate was cut into a size of 50 mm × 50 mm with a Thomson knife, immersed in a water bath at 60 ° C., and held for 2 hours. Thereafter, a sample was taken out from the water bath and the size of the shrinkage of the polarizer was measured. As a criterion for evaluation, from the viewpoint that the shrinkage is small when the adhesiveness of the adhesive is high, the size of the shrinkage is less than 1.0 mm. The above results are shown in Tables 1 to 3.

&Lt; Cold &

The prepared polarizing plate was cut into a size of 50 mm x 50 mm with a Thomson knife, and then adhered to glass via a pressure-sensitive adhesive. Then, the glass-polarized polarizing plate was left under an environment of -40 to 85 캜 cycle (30 minutes, 100 cycles), and then the length (the longest length) of the polarizer was measured visually. The length of the crack was less than 3.0 mm. The above results are shown in Tables 1 to 3.

Examples 2 to 12 and Comparative Examples 1 to 3

A resin composition for an adhesive layer and a polarizing plate using the resin composition were prepared in the same manner as in Example 1, except that the materials and mixing ratios used in preparing the resin composition for an adhesive layer were changed as shown in Tables 1 to 3 below.

(A) an epoxy resin having an isosolide structure;

ISB-DPE: isosorbide diglycidyl ether resin (trade name: ISB-DPE, product of Yokkaichikasei Co., Ltd.)

(B) aromatic epoxy resin:

EXA-850CRP: Bisphenol A type epoxy resin (trade name: EXA-850CRP, manufactured by DIC Corporation)

(C) an epoxy resin having no aromatic skeleton;

NP-E: an aliphatic epoxy resin (Neopentylglycoldiglycidylether, product name: NP-E, product of Yokkaichikasei Co., Ltd.)

2021P: alicyclic epoxy resin (trade name: Celloxide 2021P, manufactured by Daicel)

M100: 25 parts by weight of epoxycyclohexylmethyl methacrylate (trade name: Cychroma M100, manufactured by Daicel)

YX8000: hydrogenated epoxy resin (trade name: YX8000, manufactured by Mitsubishi Chemical Corporation)

(D) a (meth) acrylic resin;

4HBA: 4-hydroxybutyl acrylate (trade name: 4-HBA, manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY CO., LTD.), Which is an acrylic monomer,

PEA: Phenoxyethyl acrylate (trade name: Viscot # 192, PEA, manufactured by Osaka Yuki Kagaku Kogyo Co., Ltd.), which is an acrylic monomer,

(E) a photoacid generator;

CPI 210S: Photo acid generators (CPI 210S, manufactured by SAN-A PRO)

IR 907: Photo acid generator (product name: Irgacure 907, product of BASF)

(F) a photosensitizer;

DETX-S: Photosensitizer (product name: DETX-S, manufactured by Nippon Kayaku Co., Ltd.)

The content units of Tables 1 to 3 are parts by weight based on 100 parts by weight of the sum of components (A), (B), (C) and (D).

Example One 2 3 4 5 6 (A) ISB-DPE 10 20 40 15 15 25 (B) EXA-850CRP 30 30 20 10 20 10 (C) NP-E 60 50 20 50 45 45 2021P - - - 25 20 20 M100 - - - - - - YX8000 - - - - - - (D) 4HBA - - 10 - - 10 PEA - - 10 - - 10 (E) CPI 210S 3 3 3 3 3 3 IR 907 - - One - - - (F) DETX-S One One - One One One Initial hardenability - ○ ○ ○ ○ ○ ○ Peel strength
(PET) N / 25mm 6.0 7.0 8.0 7.0 7.0 7.5 Peel strength
(COP) N / 25mm 2.0 2.5 2.5 2.5 3.0 3.0 Cut test mm 0.2 0.1 0.2 0.1 0.1 0.1 Hot water immersion test mm 0.2 0.1 0.2 0.1 0.1 0.1 Thermal shock test mm 2.0 1.5 2.0 1.5 1.5 2.0

Example 7 8 9 10 11 12 (A) ISB-DPE 35 50 50 50 50 40 (B) EXA-850CRP - - - - - 10 (C) NP-E - - - - 20 20 2021P - - - 10 5 5 M100 65 50 50 40 25 25 YX8000 - - - - - - (D) 4HBA - - 10 - - - PEA - - 10 - - - (E) CPI 210S 3 3 3 3 3 3 IR 907 - - One - - - (F) DETX-S One One One One One One Initial hardenability - ○ ○ ○ ○ ○ ○ Peel strength
(PET) N / 25mm 6.0 5.0 6.5 4.5 4.8 4.5 Peel strength
(COP) N / 25mm 2.0 2.0 2.0 1.8 1.8 1.8 Cut test mm 0.2 0.2 0.1 0.1 0.1 0.1 Hot water immersion test mm 0.2 0.2 0.1 0.1 0.1 0.1 Thermal shock test mm 1.0 1.0 1.5 1.0 1.0 1.0

Comparative Example One 2 3 (A) ISB-DPE - - - (B) EXA-850CRP - - - (C) NP-E 70 20 - 2021P 30 80 - M100 - - - YX8000 - - 100 (D) 4HBA - - - PEA - - - (E) CPI 210S 3 3 3 IR 907 - - - (F) DETX-S One One One Initial hardenability - ○ ○ X Peel strength
(PET) N / 25mm 8.0 3.0 0.8 Peel strength
(COP) N / 25mm 2.5 3.0 0.8 Cut test mm 1.0 1.5 2.0 Hot water immersion test mm 1.0 1.5 2.5 Thermal shock test mm 50 2.0 40

As shown in Tables 1 to 3, in Examples 1 to 12 containing an epoxy resin having an isosolide structure, as compared with Comparative Examples 1 and 3 which did not contain an epoxy resin having an isosolide structure, In the test, it was found that cracks hardly occur in the polarizer, and the adhesive layers of Examples 1 to 12 are excellent in heat resistance and can prevent the occurrence of cracks in the polarizer.

In Examples 1 to 12, the peel strength of the PET film as a protective film was higher than that of Comparative Examples 2 and 3, and the peel strength of the COP film as a protective film was higher than that of Comparative Example 3. Further, in Examples 1 to 12, the peeling of the ends was small in the cutting test as compared with Comparative Examples 1 to 3. In Examples 1 to 12, peeling of the protective film did not occur in the initial curability test. From the above, it can be seen that the adhesive layers of Examples 1 to 12 have good adhesiveness to the polarizer and the protective film.

Further, in Examples 1 to 12, shrinkage of the polarizer was very small, and the adhesive layer had excellent adhesion (adhesive property) to the polarizer, even when immersed in hot water, as compared with Comparative Examples 1 to 3 .

1: polarizer
2: Polarizer
3: Protective film
9: Adhesive layer

Claims (17)

A polarizer; An adhesive layer formed on the surface of the polarizer; And a protective film pasted on at least one side of the polarizer via the adhesive layer; / RTI &gt;
Wherein the adhesive layer comprises a cured product of a resin composition containing an epoxy resin having an isosorbide structure. The polarizer according to claim 1, wherein the epoxy resin having the isosorbide structure is a diglycidylether resin. The polarizing plate according to claim 2, wherein the diglycidylether resin is a compound represented by the following formula (1): &lt; EMI ID =
[Chemical Formula 1]

. The polarizing plate according to claim 1, wherein the content of the epoxy resin having the isosolide structure is 5 wt% to 60 wt% with respect to the total of the resin composition. The polarizing plate according to claim 1, wherein the resin composition further comprises at least one of an aromatic epoxy resin and an epoxy resin having no aromatic skeleton. The resin composition according to claim 5, wherein the resin composition comprises an epoxy resin having an isosolide structure and an aromatic epoxy resin,
Wherein the weight ratio of the epoxy resin: aromatic epoxy resin having the isosolide structure is 1: 0.1 to 1: 4. 6. The resin composition according to claim 5, wherein the resin composition comprises an epoxy resin having an isosorbide structure and an epoxy resin having no aromatic skeleton,
Wherein the weight ratio of the epoxy resin having an isosolide structure to the epoxy resin having an aromatic skeleton is 1: 0.5 to 1: 6. The resin composition according to claim 5, wherein the resin composition comprises an epoxy resin having an isosolide structure, an aromatic epoxy resin, and an epoxy resin having no aromatic skeleton,
Wherein the weight ratio of the aromatic epoxy resin to the epoxy resin having no aromatic skeleton is from 1: 1 to 1: 7.5. The resin composition according to claim 5, wherein the resin composition comprises 5 to 60% by weight of an epoxy resin having an isosorbide structure, 0 to 40% by weight of an aromatic epoxy resin, and 15 to 80% by weight of an epoxy resin having no aromatic skeleton %. &Lt; / RTI &gt; The polarizer according to claim 5, wherein the resin composition further contains a (meth) acrylic resin. The polarizer according to claim 10, wherein the resin composition comprises a (meth) acrylic resin in an amount of more than 0 wt% to 50 wt%. The polarizing plate according to claim 10, wherein the (meth) acrylic resin comprises at least one of a hydroxyl group-containing (meth) acrylic monomer, a phenoxy group-containing acrylic monomer and a polymer thereof. The polarizing plate according to claim 1, wherein the resin composition further comprises any one of a photoacid generator and a photosensitizer. 14. The polarizing plate according to claim 13, wherein the content of the photoacid generator in the resin composition is 0.1 wt% to 10 wt%, and the content of the photosensitizer is 0 wt% to 3 wt%. The polarizing plate according to claim 1, wherein the thickness of the adhesive layer is 20 占 퐉 or less. The polarizer according to claim 1, wherein the adhesive layer has a peel strength of 4 N / 25 mm to 8.5 N / 25 mm on the PET film and a peel strength of 1.7 N / 25 mm to 3.5 N / 25 mm on the COP film. A display device provided with the polarizing plate according to claim 1.

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