KR102122630B1 - Adhesive composition, protective film and polarizing plate comprising adhesive layer formed by using the same and display device comprising the same - Google Patents

Abstract

The present specification relates to a polarizing plate comprising an adhesive composition and an adhesive layer formed using the adhesive composition.

Description

Adhesive composition, a protective film and a polarizing plate comprising an adhesive layer formed using the same, and an image display device including the same TECHNICAL FIELD

The present specification relates to a polarizing plate comprising an adhesive composition and an adhesive layer formed using the adhesive composition.

The polarizing plate has been used in a structure in which a protective film is laminated using an adhesive on one or both sides of a polarizer made of a polyvinyl alcohol (hereinafter referred to as'PVA') resin dyed with a dichroic dye or iodine. Conventionally, a triacetyl cellulose (TAC)-based film has been mainly used as a polarizing plate protective film, but in the case of such a TAC film, there is a problem that it is easily deformed in a high temperature and high humidity environment. Accordingly, recently, protective films of various materials that can replace the TAC film have been developed, for example, polyethylene terephthalate (PET), cycloolefin polymer (COP), acrylic film, etc. alone. Alternatively, a method of mixing and using it has been proposed.

At this time, as the adhesive used to attach the polarizer and the protective film, an aqueous adhesive composed mainly of an aqueous solution of a polyvinyl alcohol-based resin is used. However, in the case of the water-based adhesive, when using an acryl-based film or a COP film other than TAC as a protective film, there is a problem that its use is limited depending on the film material because the adhesive strength is weak. In addition, in the case of the water-based adhesive, in addition to the problem of poor adhesion depending on the material, when the material of the protective film applied to both sides of the PVA element is different, the problem of curl generation of the polarizing plate by the drying process of the water-based adhesive and initial optics Problems such as deterioration of physical properties occur. Moreover, in the case of using the water-based adhesive, a drying process is absolutely necessary, and there is a problem in that a defect rate increases due to a difference in moisture permeability and thermal expansion in the drying process. As an alternative to solve the above problems, a method of using a non-aqueous adhesive instead of a water-based adhesive has been proposed.

The non-aqueous adhesives for polarizing plates proposed to date can be divided into adhesives and cationic curing adhesives according to the curing method. The cationic curing adhesive has the advantage of having excellent adhesion to films of various materials, but has many disadvantages in the manufacturing process due to its slow curing speed and low curing degree. In order to solve the problems of the cationic curing adhesive, an adhesive based on an acrylamide-based compound has been proposed. However, in the case of an adhesive containing an acrylamide-based compound as a main component, the curing speed is faster than that of a cationic curing adhesive, but in a high-humidity atmosphere, the curing speed is slow, and there is a problem that the adhesive strength is lowered. On the other hand, since the polarizing plate manufacturing process includes a wet process in which swelling, dyeing, stretching, etc. of a polyvinyl alcohol film is performed on an aqueous solution, the water content is high. Therefore, in order to apply the acrylic amide adhesive to the polarizing plate, the polarizer before applying the adhesive It is a situation that additional processes such as hot air drying or surface treatment such as plasma should be performed.

Therefore, there is a need to develop an adhesive that does not lower curing speed and adhesion even in a high-humidity environment so that it can be applied to a polarizing plate without additional treatment.

Japanese public publication 2003-121644

The present specification provides an adhesive composition, a polarizing plate comprising an adhesive layer formed using the same.

According to an exemplary embodiment of the present specification, the cationic polymerization monomer; It provides an adhesive composition comprising a radical polymerization monomer and a crosslinking agent represented by the following formula (1).

[Formula 1]

In Formula 1, R is a substituted or unsubstituted carbon number 2 to 20 is an alkylene group, and n is 1 or 2.

According to an exemplary embodiment of the present specification, the protective film; And a protective film provided on one surface of the protective film and provided with an adhesive layer formed of the above-described adhesive composition.

According to an exemplary embodiment of the present specification, the polarizer; An adhesive layer provided on at least one surface of the polarizer and formed of the adhesive composition described above; And it provides a polarizing plate comprising a protective film provided on at least one surface on the adhesive layer.

In addition, according to an exemplary embodiment of the present specification, the display panel; And it provides an image display device including the above-described polarizing plate provided on one or both sides of the display panel.

The adhesive composition according to the exemplary embodiment of the present specification may have a high glass transition temperature after curing, and thereby a thermally stable polarizing plate may be manufactured.

In addition, as well as having excellent adhesion to films of various materials, for example, TAC film, acrylic film, COP film, PET film, etc., it is excellent in water resistance and can stably maintain adhesion even at high humidity.

Hereinafter, the present specification will be described in detail.

In the present specification, when a part is to “include” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated.

In the present specification, when a member is said to be positioned “on” another member, this includes not only the case where one member is in contact with the other member but also another member between the two members.

According to an exemplary embodiment of the present specification, the cationic polymerization monomer; It provides an adhesive composition comprising a radical polymerization monomer and a crosslinking agent represented by the following formula (1).

[Formula 1]

In Formula 1, R is a substituted or unsubstituted carbon number 2 to 20 is an alkylene group, and n is 1 or 2.

Since the adhesive composition according to an exemplary embodiment of the present specification includes a crosslinking agent including a hydroxyl group and a methacrylate functional group, it can act as a link between a cationic polymerization monomer and a radical polymerization monomer while speeding up the opening of an epoxy compound, and a polarizer It is possible to realize excellent adhesion through hydrogen bonding with and there is no stick and slip phenomenon with respect to an acrylic film, and has an effect of having an adhesion of 1.5 N/2cm or more.

According to one embodiment of the present specification, when R is an alkylene group, the glass transition temperature of the adhesive is increased. When a compound in which R is an aromatic hydrocarbon other than an alkylene is used as a crosslinking agent, the viscosity of the adhesive increases, the curing rate becomes slow, and the glass transition temperature of the cured adhesive becomes very low.

According to an exemplary embodiment of the present specification, R is ethyl or propyl.

According to one embodiment of the present specification, the crosslinking agent represented by Chemical Formula 1 is selected from the following structural formulas.

According to an exemplary embodiment of the present specification, the cationic polymerization monomer is an epoxy-based compound or an oxetane compound.

According to an exemplary embodiment of the present specification, the epoxy-based compound includes at least one epoxy group in the molecule.

According to the exemplary embodiment of the present specification, the epoxy-based compound may include an alicyclic epoxy-based compound, an aromatic epoxy-based compound, a hydrogenated epoxy-based compound, and an aliphatic epoxy-based compound. These may be used alone or in combination of two or more.

The alicyclic epoxy-based compound means an epoxy-based compound formed between two adjacent carbon atoms constituting an aliphatic hydrocarbon ring, but is not limited thereto, for example 2-(3,4- Epoxy) cyclohexyl-5,5-spiro-(3,4-epoxy)cyclohexane-m-dioxane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy -6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexane dioxide, bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy -6-methylcyclohexylmethyl) adipate, exo-exobis(2,3-epoxycyclopentyl) ether, endo-exobis(2,3-epoxycyclopentyl) ether, 2,2-bis[4-( 2,3-epoxypropoxy)cyclohexyl]propane, 2,6-bis(2,3-epoxypropoxycyclohexyl-p-dioxane), 2,6-bis(2,3-epoxypropoxy)norbor Nene, limonene dioxide, 2,2-bis(3,4-epoxycyclohexyl)propane, dicyclopentadienedioxide, 1,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4 ,7-methanoindan, p-(2,3-epoxy)cyclopentylphenyl-2,3-epoxypropyl ether, 1-(2,3-epoxypropoxy)phenyl-5,6-epoxyhexahydro-4 ,7-methanoindan, o-(2,3-epoxy)cyclopentylphenyl-2,3-epoxypropyl ether), 1,2-bis[5-(1,2-epoxy)-4,7-hexa Hydromethanoindanokisyl]ethanecyclopentenylphenylglycidyl ether, methylenebis(3,4-epoxycyclohexane)ethylene glycoldi(3,4-epoxycyclohexylmethyl) ether, ethylenebis(3,4-epoxy Cyclohexanecarboxylate), ε-caprolactone (1 to 10 mol) adducts of 3,4-epoxycyclohexane methanol and polyatomic (3 to 20 values) alcohols (GR, TMP, PE, DPE, hexapentaeryte) Ester) compounds and the like. Among these, from the viewpoint of reactivity, it is particularly preferable to use 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

In this case, the aromatic epoxy-based compound means an epoxy-based compound containing at least one aromatic hydrocarbon ring in the molecule, but is not limited thereto, for example, diglycidyl ether of bisphenol A, 4,4'-methylene Bisphenol-type epoxy resins such as diphenol diglycidyl ether, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolac-type epoxy resins such as phenol novolac epoxy resins, cresol novolac epoxy resins, and hydroxybenzaldehyde phenol novolac epoxy resins; And glycidyl ethers of tetrahydroxyphenyl methane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

In addition, the hydrogenated epoxy-based compound means an epoxy-based compound obtained by selectively performing a hydrogenation reaction under pressure in the presence of a catalyst in the presence of a catalyst, but is not limited thereto, and in particular, hydrogenated bisphenol A It is preferred to use diglycidyl ether.

In addition, the aliphatic epoxy-based compound means an epoxy-based compound containing an aliphatic chain or an aliphatic ring in the molecule, but is not limited thereto, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1 ,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl diglycidyl ether, resorcinol diglycidyl ether, diethylene glycol diglycidyl ether, ethylene glycol di Glycidyl ether, trimethylolpropane triglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and the like.

At this time, the alicyclic epoxy-based compound is an epoxy-based compound having at least two epoxy groups and at least two alicyclic rings in the molecule, for example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxyl It is particularly preferable that it is a rate or the like.

Further, the aliphatic epoxy-based compound may preferably include one or more glycidyl ether groups, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol digles Cydyl ether, 1,6-hexanediol diglycidyl ether, neopentyl diglycidyl ether, resorcinol diglycidyl ether, diethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, One selected from the group consisting of trimethylolpropane triglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and o-cresyl glycidyl ether The above may be selected.

On the other hand, the aliphatic epoxy compound is more preferably a glass transition temperature of the homopolymer of 0 ℃ to 60 ℃ degree.

According to an exemplary embodiment of the present invention, it is preferable to use one or more of the alicyclic epoxy-based compound and one or more of the aliphatic epoxy-based compound. In the case of an alicyclic epoxy, it is preferable because it has a fast curing rate and a high Tg, but the viscosity is high, so it is not possible to add a large amount to the adhesive formulation, and an aliphatic epoxy has a lower curing rate and Tg than an alicyclic epoxy, but is used with an alicyclic epoxy. By lowering the adhesive viscosity, processability can be secured, and the adhesive strength, curing speed, and Tg of the adhesive can be suitably adjusted.

According to one embodiment of the present specification, the oxetane compound is not particularly limited as long as it has at least one oxetanyl group in the molecule, and various oxetane compounds well known in the art may be used. For example, as the oxetane compound of the present invention, 3,3'-oxybis(methylene)bis(3-ethyloxetane), 3-ethyl-3-[(3-ethyloxetane-3-yl )Methoxymethyl]oxetane, 1,4-bis[(3-ethyloxetan-3-yl)methoxymethyl]benzene, 1,4-bis[(3-ethyloxetan-3-yl)methoxy Benzene, 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene, 1,2-bis[(3-ethyloxetan-3-yl)methoxy]benzene, 4,4 '-Bis[(3-ethyloxetan-3-yl)methoxy]biphenyl, 2,2'-bis[(3-ethyloxetan-3-yl)methoxy]biphenyl, 3,3', 5,5'-tetramethyl-4,4'-bis[(3-ethyloxetan-3-yl)methoxy]biphenyl, 2,7-bis[(3-ethyloxetan-3-yl)meth Thoxy]naphthalene, bis[4-{(3-ethyloxetan-3-yl)methoxy}phenyl]methane, bis[2-{(3-ethyloxetan-3-yl)methoxy}phenyl]methane, Etherification of 2-, 2-bis [4-{(3-ethyloxetan-3-yl)methoxy}phenyl] propane, novolak-type phenol-formaldehyde resin with 3-chloromethyl-3-ethyloxetane Modified product, 3(4),8(9)-bis[(3-ethyloxetan-3-yl)methoxymethyl]-tricyclo[5.2.1.0 2,6]decane, 2,3-bis[( 3-ethyloxetan-3-yl)methoxymethyl]norbornane, 1,1,1-tris[(3-ethyloxetan-3-yl)methoxymethyl]propane, 1-butoxy-2, 2-bis[(3-ethyloxetan-3-yl)methoxymethyl]butane, 1,2-bis[{2-(3-ethyloxetan-3-yl)methoxy}ethylthio]ethane, bis [{4-(3-ethyloxetan-3-yl)methylthio}phenyl] sulfide, 1,6-bis[(3-ethyloxetan-3-yl)methoxy]- 2,2,3, And 3,4,4,5,5-octafluorohexane.

When having two oxetanyl groups as an oxetane compound, it is effective to increase the glass transition temperature of the adhesive layer, and when it has one oxetanyl group, it is advantageous for adhesion.

According to the exemplary embodiment of the present specification, the cationic polymerization monomer uses an epoxy-based compound and an oxetane compound simultaneously. When an epoxy compound and an oxetane compound are used simultaneously, the curing rate of an epoxy group having a low photocationic curing rate can be increased by using an oxetane compound, and oxetane is used as a reactive diluent to have a high viscosity. The fairness of the adhesive can be ensured.

According to an exemplary embodiment of the present specification, the radical polymerization monomer is a monofunctional acrylic compound and a polyfunctional acrylic compound.

According to an exemplary embodiment of the present specification, the monofunctional acrylic compound is a hydroxyl group acrylate.

According to an exemplary embodiment of the present specification, the polyfunctional acrylic compound is a bifunctional acrylic crab compound.

According to an exemplary embodiment of the present specification, the radical polymerization monomer is a diacrylate-based compound.

According to an exemplary embodiment of the present specification, the radical polymerization monomer is tricyclodecane dimethanol diacrylate, hexanediol diacrylate tripropylene glycol diacrylate, dipropylene glycol diacrylate, butanediol diacrylate, hydroxy pival Late neopentyl glycol acrylate, triethylene glycol diacrylate and 1,9-nonanediol diacrylate.

According to an exemplary embodiment of the present specification, with respect to the total 100 parts by weight of the adhesive composition, the cationic polymerization monomer 29 to 80 parts by weight, the radical polymerization monomer 10 to 70 parts by weight, and the crosslinking agent represented by the formula (1) It contains 1 to 30 parts by weight, preferably, 50 to 70 parts by weight of the cationic polymerization monomer, 20 to 35 parts by weight of the radical polymerization monomer, and 5 to 15 parts by weight of the crosslinking agent represented by Chemical Formula 1.

When the cationic polymerization monomer satisfies the above range, it is excellent in improving the adhesive strength and water resistance of the adhesive composition, and when the radical polymerization monomer satisfies the above range, the effect of increasing the physical properties of the adhesive composition is excellent, than the cationic polymerization monomer. Since the curing speed is relatively fast, it has an excellent effect on the initial curing speed and curing degree of the adhesive, and when the crosslinking agent including the hydroxyl group and the methacrylate functional group satisfies the above range, it serves as a crosslinking role between the epoxy group and the acrylate group of the adhesive composition. It has an excellent effect of increasing physical properties and adhesion.

According to the exemplary embodiment of the present specification, the glass transition temperature of the adhesive composition is 60°C or higher, preferably 70°C or higher, and the higher the glass transition temperature is, the more thermally stable, so the upper limit is not particularly limited. It is preferable that it is 200 degrees C or less.

In this specification, the glass transition temperature is a differential scanning calorimeter (DSC, Mettler Co., Ltd.), a sample of about 10mg is sealed in a dedicated pen, and heat is absorbed by the material due to the phase change when heated to a constant heating environment. And it is the value that measured the glass transition temperature by drawing the calorific value according to the temperature.

<glass transition temperature( Tg ) Measurement method>

The glass transition temperature of the adhesive layer was checked using a differential scanning calorimeter (DSC, Mettler). After separating the adhesive layer of the polarizing plate manufactured under the above curing conditions, the temperature was raised to -30 to 200°C to measure the glass transition temperature in the second run.

According to one embodiment of the present specification, the adhesive composition may further include a cationic initiator, a radical initiator, a photosensitizer, and the like.

Cationic initiator according to an exemplary embodiment of the present specification is a compound that generates an acid (H +) by active energy rays, the cationic initiator usable in the present invention is a sulfonium salt or iodonium salt It is preferably included. Specific examples of the photoacid generator including sulfonium salt or iodonium salt include diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate (Diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate), diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, (phenyl)[4-(2-methylpropyl)phenyl]-iodinium hexafluorophosphate ((phenyl)[4-(2-methylpropyl) phenyl]-Iodonium hexafluorophosphate), (thiodi-4,1-phenylene)bis(diphenylsulfonium) dihexafluoroantimonate ((Thiodi-4,1 -phenylene)bis(diphenylsulfonium) dihexafluoroantimonate) and (thiodi-4,1-phenylene)bis(diphenylsulfonium) dihexafluorophosphate ((Thiodi-4,1-phenylene)bis(diphenylsulfonium) dihexafluorophosphate) One or more selected from the group consisting of may be mentioned, but is not limited thereto.

The radical initiator according to an exemplary embodiment of the present specification is to promote the radical polymerizability to improve the curing rate, and the radical initiators generally used in the art may be used without limitation.

The photosensitizer according to the exemplary embodiment of the present specification includes, for example, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, anthracene compounds, halogen compounds, and photoreducing dyes. However, it is not limited thereto.

In addition, the adhesive composition for the polarizing plate of the present invention may further include a silane coupling agent, if necessary, together with the components. When a silane coupling agent is included, the silane coupling agent lowers the surface energy of the adhesive, thereby improving the adhesive wetting.

In this case, it is more preferable that the silane coupling agent contains a cationic polymerizable functional group such as an epoxy group, a vinyl group, and a radical group. In addition, when using a silane coupling agent that does not contain a cationic polymerizable functional group, compared with a surfactant or a silane coupling agent that does not contain a cationic polymerizable functional group, the effect of improving the wetting property without lowering the glass transition temperature There is. This is because the cationic polymerization functional group of the silane coupling agent reacts with the silane group of the adhesive composition to form a crosslinked form while reducing the phenomenon in which the glass transition temperature of the adhesive layer decreases after curing.

The silane coupling agent usable in the present invention may be a silane coupling agent represented by the following Chemical Formula 2, but is not limited thereto.

[Formula 2]

Si(R1)m(R2) _{4 -m}

In Formula 2, R1 is a cationic polymerizable functional group bonded to a silicon atom, and is a functional group containing a cyclic ether group or a vinyloxy group, and R2 is a hydrogen, hydroxy group, alkyl group or alkoxy group bonded to the silicon atom. , m is an integer from 1 to 4.

According to an exemplary embodiment of the present specification, the adhesive strength of the adhesive composition is 1 N/2cm or more, preferably 1.5 N/2cm or more and 20 N/2cm or less.

The adhesive force in this specification is a value measured through a peeling experiment of a polarizing plate. Specifically, in the peeling experiment, the prepared polarizing plate was cut to a width of 20 mm and a length of 100 mm, and the peeling force of the polarizer and the polymer film was measured at a speed of 300 m/min and 90 degrees using a Texture Analyzer device (TA-XT Plus from Stable Micro Systems). Mean value.

According to an exemplary embodiment of the present specification, the protective film; And a protective film provided on one surface of the protective film and provided with an adhesive layer formed of the above-described adhesive composition.

According to an exemplary embodiment of the present specification, the protective film is an acrylic film.

According to one embodiment of the present specification, the adhesive force of the adhesive layer is 1.5 N/2 cm or more with respect to the acrylic film.

According to an exemplary embodiment of the present specification, the polarizer; An adhesive layer provided on at least one surface of the polarizer and formed of the adhesive composition described above; And it provides a polarizing plate comprising a protective film provided on at least one surface on the adhesive layer.

According to an exemplary embodiment of the present specification, the protective film provides a polarizing plate that is an acrylic film.

According to an exemplary embodiment of the present specification, the adhesive force of the adhesive layer provides a polarizing plate that is at least 1.5 N / 2cm with respect to the acrylic film.

The polarizer is not particularly limited, and a polarizer well known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye may be used. The polarizer may be prepared by dyeing iodine or a dichroic dye on a PVA film, but the manufacturing method thereof is not particularly limited. In the present specification, the polarizer means a state that does not include a protective film, and the polarizer means a state that includes a polarizer and a protective film.

Next, the adhesive layer is formed using the adhesive composition according to the above-described embodiments of the present specification, and may be formed by a method well known in the art. For example, it may be performed by applying an adhesive composition to one surface of the polarizer or the protective film to form an adhesive layer, and then curing the polarizer and the protective film after plywood. At this time, the coating may be performed by coating methods well known in the art, for example, spin coating, bar coating, roll coating, gravure coating, blade coating, or the like.

Meanwhile, the curing may be performed by irradiating active energy rays such as light curing, more specifically ultraviolet rays, visible rays, and electron beam X-rays. For example, it may be performed by a method of irradiating ultraviolet rays of about 10 to 2500 mJ/cm ² by using an ultraviolet irradiation device (Metal halide lamp).

Alternatively, the curing may be performed by thermal curing, more specifically, thermal curing at a curing temperature of 80°C or higher. At this time, if necessary, a known amine-based initiator may be additionally added to the composition in order to accelerate the curing rate during thermal curing.

Alternatively, the curing may be to further perform thermal curing after the photo-curing, or to further perform photo-curing after the thermal curing.

On the other hand, the thickness of the adhesive layer is more than about 0 to 20㎛, about 0 to about 10㎛, preferably 0.1 to 10㎛ or about 0.1 to 5㎛. This is because when the thickness of the adhesive layer is too thin, the uniformity and adhesive strength of the adhesive layer may be deteriorated, and when the thickness of the adhesive layer is too thick, the appearance of the polarizing plate may wrinkle.

The protective film is for supporting and protecting the polarizer, and protective films of various materials generally known in the art, for example, cellulose-based films, polyethylene terephthalate (PET) films, and cycloolefin polymers (COP, cycloolefin polymer) film, acrylic film and the like can be used without limitation. Among these, it is particularly preferable to use an acrylic film when considering optical properties, durability, economical efficiency, and the like.

Meanwhile, the acrylic film usable in the present specification can be obtained by molding a molding material containing a (meth)acrylate-based resin as a main component by extrusion molding. At this time, the (meth) acrylate-based resin is a resin containing a (meth) acrylate-based unit as a main component, as well as a homopolymer resin composed of a (meth) acrylate-based unit, as well as a (meth) acrylate-based unit In addition, it is a concept including a copolymer resin in which other monomer units are copolymerized and a blend resin in which other resins are blended in the (meth)acrylate-based resin as described above.

Meanwhile, the (meth)acrylate-based unit may be, for example, an alkyl (meth)acrylate-based unit. Here, the alkyl (meth) acrylate-based unit means both an alkyl acrylate-based unit and an alkyl methacrylate-based unit, and the alkyl group of the alkyl (meth) acrylate-based unit preferably has 1 to 10 carbon atoms. , It is more preferably having 1 to 4 carbon atoms.

Moreover, as a monomer unit which can be copolymerized with the said (meth)acrylate type unit, a styrene type unit, a maleic anhydride type unit, a maleimide type unit, etc. are mentioned. In this case, the styrene-based unit is not limited to this, and examples thereof include styrene, α-methylstyrene, and the like; Examples of the maleic anhydride-based monomer include, but are not limited to, maleic anhydride, methyl maleic anhydride, cyclohexyl maleic anhydride, phenyl maleic anhydride, and the like; Examples of the maleimide-based monomer include, but are not limited to, maleimide, N-methyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, and the like. These can be used alone or in combination.

Meanwhile, the acrylic film may be a film containing a (meth)acrylate-based resin having a lactone ring structure. As a specific example of the (meth)acrylate-based resin having a lactone ring structure, for example, lactones described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, etc. (Meth)acrylate-type resin which has a ring structure is mentioned.

The method for producing the acrylic film is not particularly limited, for example, (meth) acrylate-based resin and other polymers, additives, etc. are sufficiently mixed by any suitable mixing method to prepare a thermoplastic resin composition, and then film forming it Or a (meth) acrylate-based resin, other polymers, additives, etc. are prepared as separate solutions and mixed to form a uniform mixed solution, followed by film molding. Further, the acrylic film may be either an unstretched film or a stretched film. In the case of a stretched film, it may be a uniaxially stretched film or a biaxially stretched film, and in the case of a biaxially stretched film, it may be either a simultaneous biaxially stretched film or a sequential biaxially stretched film.

Meanwhile, the polarizing plate of the present specification may further include a primer layer between the adhesive layer and the protective film in order to further improve adhesion. At this time, the primer layer may be formed by a method of applying a coating solution containing a water-dispersible polymer resin, water-dispersible fine particles, and water on a protective film using a bar coating method, a gravure coating method, and the like. The water-dispersible polymer resin may be, for example, water-dispersible polyurethane-based resin, water-dispersible acrylic resin, water-dispersible polyester-based resin, or a combination thereof, and the water-dispersible fine particles are inorganic fine particles such as silica, titania, alumina, and zirconia. B, but may be used, but not limited to, organic-based fine particles made of silicone-based resin, fluorine-based resin, (meth)acrylic-based resin, cross-linked polyvinyl alcohol and melamine-based resin or a combination thereof.

According to one embodiment of the present specification, the glass transition temperature of the adhesive layer is 60°C or higher, preferably 70°C or higher, and the upper limit is not particularly limited, but is generally 200°C or lower.

According to an exemplary embodiment of the present specification, when the glass transition temperature of the adhesive layer is 70 ℃ or more, in the durability evaluation, such as thermal shock property evaluation, exhibited excellent effects in the appearance properties, adhesion, crack occurrence and optical properties of the polarizing plate.

In this specification, the glass transition temperature is a differential scanning calorimeter (DSC, Mettler Co., Ltd.), a sample of about 10mg is sealed in a dedicated pen, and heat is absorbed by the material due to the phase change when heated to a constant heating environment. And it is the value that measured the glass transition temperature by drawing the calorific value according to the temperature.

<Method for measuring glass transition temperature (Tg)>

The glass transition temperature of the adhesive layer was checked using a differential scanning calorimeter (DSC, Mettler). After separating the adhesive layer of the polarizing plate manufactured under the above curing conditions, the temperature was raised to -30 to 200°C to measure the glass transition temperature in the second run.

According to an exemplary embodiment of the present specification, the display panel; And a polarizing plate according to the above-described embodiment provided on one or both surfaces of the display panel.

The display panel may be a liquid crystal panel, a plasma panel, and an organic light emitting panel.

Accordingly, the image display device may be a liquid crystal display (LCD), a plasma display (PDP), and an organic light emitting display (OLED).

More specifically, the image display device may be a liquid crystal display device including a liquid crystal panel and polarizing plates provided on both sides of the liquid crystal panel, wherein at least one of the polarizing plates is in accordance with one embodiment of the present specification described above. It may be a polarizing plate including a polarizer. That is, the polarizing plate is a polarizing plate comprising a protective film provided on at least one surface of the polyvinyl alcohol-based polarizer and the polyvinyl alcohol-based polarizer dyed with iodine and/or dichroic dye, in a wavelength range of 400 nm to 800 nm locally. It has a simplex transmittance of 80% or more of the polarization canceling region, the arithmetic mean roughness (Ra) of the polarization canceling region is 200nm or less, the polarization degree is 10% or less, sagging (sagging) is characterized in that less than 10㎛.

In this case, the type of the liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, without being limited to the type, a passive matrix type panel such as a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferroelectric (F) type or a polymer dispersed (PD) type; An active matrix panel such as a two-terminal type or a three-terminal type; All well-known panels such as an in-plane switching (IPS) panel and a vertical alignment (VA) panel may be applied. In addition, other configurations constituting the liquid crystal display device, for example, types of upper and lower substrates (for example, color filter substrates or array substrates) are also not particularly limited, and configurations known in the field are not limited. Can be employed.

Hereinafter, it will be described in more detail through examples. However, the following examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.

Comparative example One

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 70/3 parts by weight, neopentyl glycol diglycidyl ester 70/3 parts by weight, 3,3'-oxybis(methylene)bis(3 -Ethyl oxetane) (3,3'-oxybis(methylene)bis(3-ethyloxetane)) 70/3 parts by weight, 30 parts by weight of dipropylene glycol diacrylate, 100 parts by weight of the prepared composition, Irgacure 250 ( Manufacturer: Basf) 2.5 parts by weight, Irgacure 819 (manufacturer: Basf) 1 part by weight, Isopropylthioxanthone (ITX) (manufacturer: SK cytec) 1 part by weight to prepare an adhesive composition.

Example One

3,4-epoxycyclohexylmethyl 20 parts by weight of 3,4-epoxycyclohexane carboxylate, 20 parts by weight of neopentyl glycol diglycidyl ester, 3,3'-oxybis(methylene)bis(3-ethyloxetane ) (3,3'-oxybis(methylene)bis(3-ethyloxetane)) 20 parts by weight, 10 parts by weight of hydroxyethyl methacrylate (HEMA), 30 parts by weight of dipropylene glycol diacrylate, 100 parts by weight With respect to parts, Irgacure 250 (manufacturer: Basf) 2.5 parts by weight, Irgacure 819 (manufacturer: Basf) 1 part by weight, Isopropylthioxanthone (ITX) (manufacturer: SK cytec) 1 part by weight to prepare an adhesive composition.

Example 2

3,4-epoxycyclohexylmethyl 20 parts by weight of 3,4-epoxycyclohexane carboxylate, 20 parts by weight of neopentyl glycol diglycidyl ester, 3,3'-oxybis(methylene)bis(3-ethyloxetane ) (3,3'-oxybis(methylene)bis(3-ethyloxetane)) 20 parts by weight, 2,3-dihydroxypropyl methacrylate (GLM) 10 parts by weight, dipropylene glycol diacrylate 30 parts by weight With respect to 100 parts by weight of the prepared composition, Irgacure 250 (manufacturer: Basf) 2.5 parts by weight, Irgacure 819 (manufacturer: Basf) 1 part by weight, Isopropylthioxanthone (ITX) (manufacturer: SK cytec) 1 part by weight to prepare an adhesive composition .

Glass transition temperature evaluation

The glass transition temperatures of the adhesive compositions prepared according to Examples 1, 2 and Comparative Example 1 were measured, and the measurement method was as described above. The results are shown in Table 1 below.

Glass transition temperature (Tg) (℃) Comparative Example 1 86 Example 1 78 Example 2 76

Adhesion evaluation

The adhesive strength of the adhesive composition prepared according to Examples 1 and 2 and Comparative Example 1 was measured for an acrylic film that was not subjected to primer treatment, and the measuring method is as described above. Table 2 shows the results.

Adhesion (N/2cm) Acrylic film Stick-slip Comparative Example 1 0.9 ◎ Example 1 1.9 X Example 2 1.8 X

In the present specification, ◎ is a stick slip phenomenon, ○: stick slip phenomenon occurs, and X: means no stick slip phenomenon.

In Tables 1 and 2, Examples 1 and 2, which are compositions containing a crosslinking agent including a hydroxyl functional group and a methacrylate functional group according to an exemplary embodiment of the present specification, include a crosslinking agent comprising a hydroxyl group and a methacrylate functional group. It was confirmed that the adhesive strength was higher than that of the adhesive composition of Comparative Example 1 that was not performed, and Comparative Example 1 was able to confirm that a stick and a slip phenomenon appeared.

HEMA Evaluation of adhesion according to content (fixation of cationic polymerization monomer content)

The content of the cationic polymerization monomer is fixed as in the composition of Example 1, and the weights of hydroxydecyl methacrylate (HEMA) and dipropylene glycol diacrylate (DPGDA) are prepared in the ratios shown in Table 3 below. Table 3 shows the results of the adhesive strength evaluation by the aforementioned method.

Epoxy Oxetane HEMA
(Parts by weight) DPGDA
(Parts by weight) Initiator Adhesion [N/2cm] CEL2021P
(Parts by weight) NPDGE
(Parts by weight) OXT221
(Parts by weight) I250 I819 ITX Acrylic film Stick-slip Comparative Example 2 20 20 20 - 40 2.5pt 1pt 1pt 0.7 ◎ Example 3 20 20 20 5 35 1.3 ○ Example 1 20 20 20 10 30 1.9 X Example 4 20 20 20 15 25 1.4 X Example 5 20 20 20 20 20 1.0 X

HEMA Evaluation of adhesion according to the content (fixed content of radical polymerization monomer)

The content of the radical polymerization monomer is fixed as in the composition of Example 1, and the weights of the hydroxydetyl methacrylate (HEMA) and the cationic polymerization monomer are prepared at a ratio shown in Table 4 below to evaluate adhesion by the method described above. Table 4 shows the results of the process.

Epoxy Oxetane HEMA
(Parts by weight) DPGDA
(Parts by weight) Initiator Adhesion [N/2cm] CEL2021P
(Parts by weight) NPDGE
(Parts by weight) OXT221
(Parts by weight) I250 I819 ITX Acrylic film Stick-slip Comparative Example 1 70/3 70/3 70/3 - 30 2.5pt 1pt 1pt 0.9 ◎ Example 6 65/3 65/3 65/3 5 30 1.3 ○ Example 1 20 20 20 10 30 1.9 X Example 7 55/3 55/3 55/3 15 30 1.6 X Example 8 50/3 50/3 50/3 20 30 1.1 X

Evaluation of adhesion according to GLM content (fixation of cationic polymerization monomer content)

The content of the cationic polymerization monomer is fixed as in the composition of Example 2, and the weights of 2,3-dihydroxypropyl methacrylate (GLM) and dipropylene glycol diacrylate (DPGDA) are shown in Table 5 below. Table 5 shows the results of the evaluation of the adhesive strength by preparing the composition as described above.

Epoxy Oxetane GLM
(Parts by weight) DPGDA
(Parts by weight) Initiator Adhesion [N/2cm] CEL2021P
(Parts by weight) NPDGE
(Parts by weight) OXT221
(Parts by weight) I250 I819 ITX Acrylic film Stick-slip Comparative Example 2 20 20 20 - 40 2.5pt 1pt 1pt 0.7 ◎ Example 9 20 20 20 5 35 1.4 ○ Example 2 20 20 20 10 30 1.8 X Example 10 20 20 20 15 25 1.2 X Example 11 20 20 20 20 20 0.8 X

GLM Evaluation of adhesion according to the content (fixed content of radical polymerization monomer)

The content of the radically polymerized monomer is fixed as in the composition of Example 2, and the weight of 2,3-dihydroxypropyl methacrylate (GLM) and the cationic polymerized monomer is prepared in a ratio described in Table 6 below. Table 6 shows the results of the adhesive strength evaluation in one method.

Epoxy Oxetane GLM
(Parts by weight) DPGDA
(Parts by weight) Initiator Adhesion [N/2cm] CEL2021P
(Parts by weight) NPDGE
(Parts by weight) OXT221
(Parts by weight) I250 I819 ITX Acrylic film Stick-slip Comparative Example 1 70/3 70/3 70/3 - 30 2.5pt 1pt 1pt 0.9 ◎ Example 12 65/3 65/3 65/3 5 30 1.3 ○ Example 2 20 20 20 10 30 1.8 X Example 13 55/3 55/3 55/3 15 30 1.3 X Example 14 50/3 50/3 50/3 20 30 1.0 X

Claims (19)

Cationic polymerization monomer; In the adhesive composition comprising a radical polymerization monomer and a crosslinking agent represented by the formula (1),
The cationic polymerization monomer is an adhesive composition comprising an epoxy-based compound and an oxetane compound:
[Formula 1]

In Chemical Formula 1, R is a substituted or unsubstituted alkylene group having 2 to 20 carbon atoms, and n is 1 or 2. The method according to claim 1, wherein the cross-linking agent represented by the formula (1) is a cross-linking agent selected from the following structural formula.

delete delete The method according to claim 1, wherein the radical polymerization monomer is a diacrylate-based adhesive composition. The method according to claim 1, The radical polymerization monomer comprises at least one compound selected from the group consisting of tricyclodecane dimethanol diacrylate, hexanediol diacrylate and tripropylene glycol diacrylate, dipropylene glycol diacrylate Adhesive composition. The method according to claim 1, with respect to the total 100 parts by weight of the adhesive composition,
29 to 80 parts by weight of the cationic polymerization monomer,
10 to 70 parts by weight of the radical polymerization monomer, and
The adhesive composition comprising 1 to 30 parts by weight of the crosslinking agent represented by the formula (1). The method according to claim 1, based on 100 parts by weight of the adhesive composition,
50 to 70 parts by weight of the cationic polymerization monomer,
20 to 35 parts by weight of the radical polymerization monomer, and
The adhesive composition comprising 5 to 15 parts by weight of the crosslinking agent represented by the formula (1). The method according to claim 1, The glass transition temperature (Tg) of the adhesive composition is 60 °C or more adhesive composition. The adhesive composition of claim 1, wherein the adhesive strength of the adhesive composition is 1.5 N/2 cm or more with respect to the acrylic film. Protective film; And an adhesive layer provided on one side of the protective film and formed of an adhesive composition according to any one of claims 1, 2 and 5 to 10. The protective film of claim 11, wherein the protective film is an acrylic film. The protective film of claim 12, wherein the adhesive force of the adhesive layer is 1.5 N/2 cm or more with respect to the acrylic film. Polarizer;
An adhesive layer provided on at least one surface of the polarizer and formed of an adhesive composition according to any one of claims 1, 2 and 5 to 10; And
A polarizing plate comprising a protective film provided on at least one surface on the adhesive layer. The polarizing plate according to claim 14, wherein the protective film is an acrylic film. The polarizing plate of claim 14, wherein the adhesive force of the adhesive layer is 1.5 N/2 cm or more with respect to the acrylic film. The method according to claim 14, The glass transition temperature of the adhesive layer is a polarizing plate of 70 ℃ or more. The method according to claim 14, The thickness of the adhesive layer is more than 0㎛ 20㎛ less polarizing plate. Display panel; And
An image display device comprising the polarizing plate according to claim 14 provided on one or both sides of the display panel.