WO2015046720A1

WO2015046720A1 - Polarizing plate

Info

Publication number: WO2015046720A1
Application number: PCT/KR2014/005702
Authority: WO
Inventors: 박광승; 조해성; 손현희; 이남정; 박준욱; 허은수; 이미린; 전성현
Original assignee: 주식회사 엘지화학
Priority date: 2013-09-30
Filing date: 2014-06-26
Publication date: 2015-04-02

Abstract

The present invention relates to a polarizing plate comprising a polarizer and a protective film formed on at least one surface of the polarizer, wherein the protective film is formed of a composition for a polarizing plate protective film, the composition comprising: at least one curable compound selected from the group consisting of a compound having a functional group and an ethylenically unsaturated bond, and a ring-opening polymer compound; a non-curable polymer having a functional group at a side chain; and a polymerization initiator, wherein the functional group comprises at least one of O, N and F atoms.

Description

Polarizer

The present invention relates to a polarizing plate, and more particularly, to a polarizing plate manufactured by using a composition for polarizing plate protective film having a low curing shrinkage ratio and excellent thermal stability and optical properties.

Conventional polarizers have been used in a structure in which a protective film is laminated using adhesives on both sides of a polarizer made of a polyvinyl alcohol (hereinafter, referred to as 'PVA')-based resin, which is usually dyed with dichroic dye or iodine. However, as the trend of thinning of display devices has recently accelerated, single-sided polarizing plates having a protective film on only one surface of the polarizer and forming an adhesive layer immediately without a protective film have been developed to reduce the thickness of the polarizing plate. However, in the case of the single-sided polarizing plate in which the adhesive layer is directly formed on the polarizer as described above, the durability of the single-sided polarizing plate is poor, so if the polarizer is easily cracked when raised under a harsh environment, curling occurs due to the shrinkage difference between the protective film and the adhesive layer. There was a problem such as causing a light leakage phenomenon when mounted on.

In order to solve the above problems, a technique for forming a protective film using a cationic curable resin or a radical curable resin between the polarizer and the adhesive layer of the single-sided polarizing plate has been proposed. However, the proposed composition for forming a protective film has a very high cure shrinkage rate because all monomers, oligomers or polymers included in the composition contain a curable reactor, and as a result, the protective film shrinks during curing of the protective film, thereby generating curls. There is a problem that stability is impaired. On the other hand, in order to lower the cure shrinkage rate of the protective film-forming compositions, a method of mixing a polymer without a curable reactor or a solid inorganic material such as carbon black may be considered. However, in the case of mixing the solid inorganic materials, problems such as coloring and light scattering occur, which tends to inhibit optical properties, and in the case of mixing a polymer having no curable reactor, two or more glass transition temperatures of the composition occur. There is a problem that the thermal stability is poor due to the phenomenon.

Accordingly, development of a protective film for polarizing plates having low curing shrinkage and excellent thermal stability and optical properties is desired.

The present invention is to solve the above problems, to provide a polarizing plate having a low curing shrinkage, a protective film that does not inhibit the thermal stability and optical properties of the polarizing plate.

To this end, the present invention includes a polarizer and a protective film formed on at least one surface of the polarizer, the protective film is a compound having an ethylenically unsaturated bond with a functional group containing at least one of O, N and F atoms and ring-opening polymerizable At least one curable compound selected from the group consisting of compounds; An uncured polymer comprising a functional group comprising at least one of O, N and F atoms in the side chain; And it provides the polarizing plate formed by the composition for polarizing plate protective films containing a polymerization initiator.

At this time, the composition for the polarizing plate protective film, 70 to 98.5 weight of at least one curable compound selected from the group consisting of a compound having at least one or more of O, N and F atoms and a compound having an ethylenically unsaturated bond and a ring-opening polymerizable compound It is preferred to include 1 to 20 parts by weight of the non-curable polymer containing a functional group containing at least one of O, N and F atoms in the side chain, and 0.5 to 10 parts by weight of the polymerization initiator.

On the other hand, in the present invention, the functional group containing at least one of the O, N and F atoms is selected from the group consisting of hydroxy group, amine group, amide group, urethane group, carboxyl group, acid anhydride group, oxazoline group and fluorine group It may be one or more.

In addition, the compound having an ethylenically unsaturated bond with a functional group including at least one or more of the O, N and F atoms may be an acrylic compound, a vinyl compound, or a combination thereof, for example, hydroxy (meth) Acrylate monomer, hydroxy (meth) acrylate oligomer, carboxyl (meth) acrylate monomer, carboxyl (meth) acrylate oligomer, acrylamide monomer, acrylamide oligomer, urethane (meth) acrylic Rate monomer, urethane (meth) acrylate oligomer, acid anhydride (meth) acrylate monomer, acid anhydride (meth) acrylate oligomer, oxazoline (meth) acrylate monomer, oxazoline (meth) acrylic Rate oligomer, vinyl pyrrolidone monomer, vinyl pyrrolidone oligomer, acryloyl morpholine monomer acryloyl morphol System, and oligomers or a combination thereof, for example, the may be at least one member selected from the group consisting of the compound represented by the formula.

The ring-opening polymerizable compound may be an epoxy compound, an oxetane compound, or a combination thereof, but is not limited thereto. For example, an epoxy compound, a hydrogenated epoxy compound, an alicyclic epoxy compound, and an aliphatic epoxy It may be a compound, an oxetane compound or a combination thereof.

Next, the non-curable polymer including a functional group containing at least one of O, N and F atoms in the side chain, for example, vinyl alcohol polymer or copolymer, vinyl acrylic acid polymer or copolymer, vinyl It may be a rollidone polymer or copolymer, a vinyl acetate polymer or copolymer, an amide polymer or copolymer, a vinylidene fluoride polymer or copolymer, a urethane polymer or a copolymer, or a combination thereof, and the polymerization initiator may be a cation It may be a polymerization initiator, a radical polymerization initiator or a combination thereof.

On the other hand, in the present invention, the composition for polarizing plate protective film is about 7% to 13% of the cure shrinkage at 20 ℃, the glass transition temperature is about 60 to 200 ℃ degree, the viscosity is preferably about 30cP to 500cP. .

In addition, the polarizing plate of the present invention, if necessary, the protective film is attached to the opposite side of the surface on which the protective film of the polarizer is formed via the adhesive layer, or may further include an adhesive layer on the protective film. In this case, the protective film may be a cellulose film, a polyethylene terephthalate (PET) film, a cycloolefin polymer (COP) film, or an acrylic film.

In another aspect, the present invention provides a display device including the polarizing plate of the present invention.

Since the composition for protective films used in the present invention includes a curable component and a non-curable polymer together, the curing shrinkage rate is low, thereby minimizing the polarizing plate curl generated when the protective film is cured.

In addition, in the polarizing plate of the present invention, since the curable compound and the non-curable polymer are present in the hydrogen bonded state in the protective film, double Tg does not occur and has stable thermal characteristics.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The present inventors have repeatedly studied to solve the problem of shrinkage during curing of the polarizing plate protective film, when forming a protective film using a composition containing a curable compound and a non-curable polymer that can hydrogen bond with the curable compound, The present invention was completed by finding that the shrinkage rate of curing of the protective film can be lowered without lowering the thermal and optical properties of the film.

More specifically, the polarizing plate of the present invention includes a polarizer and a protective film formed on at least one surface of the polarizer, wherein the protective film comprises (1) a curable compound (2) a non-curable polymer and (3) a polymerization initiator. It is characterized by being formed by the composition for.

At this time, the (1) the curable compound may be at least one selected from the group consisting of a compound having an ethylenically unsaturated bond and a ring-opening polymerizable compound, wherein the compound having an ethylenically unsaturated bond is one of O, N and F atoms Functional groups comprising at least one or more. This is because, when the compound having an ethylenically unsaturated bond includes the functional group as described above, stable thermal properties can be realized by hydrogen bonding with (2) the non-curable polymer described later. In the case of the ring-opening polymerizable compound, a functional group containing O, N and / or F atoms is often generated after the ring-opening reaction, so that a separate functional group is not required for hydrogen bonding, but if necessary, the ring-opening polymerizable compound Also, functional groups containing O, N and / or F atoms may be included.

On the other hand, the functional group containing at least one or more of the O, N and F atoms is not limited to this, for example, hydroxy group, amine group, amide group, urethane group, carboxyl group, anhydride group, oxazoline group and fluorine It may be one or more selected from the group consisting of groups.

On the other hand, the compound having a functional group and an ethylenically unsaturated bond containing at least one or more of the O, N and F atoms usable in the present invention, may be an acrylic compound, a vinyl compound or a combination thereof, for example, Hydroxy (meth) acrylate monomers, hydroxy (meth) acrylate oligomers, carboxyl (meth) acrylate monomers, carboxyl (meth) acrylate oligomers, acrylamide monomers, acrylamide oligomers, Urethane (meth) acrylate monomers, urethane (meth) acrylate oligomers, acid anhydride (meth) acrylate monomers, acid anhydride (meth) acrylate oligomers, oxazoline (meth) acrylate monomers, oxazoline (Meth) acrylate oligomer, vinyl pyrrolidone monomer, vinyl pyrrolidone oligomer, acryloyl morpholine Nomeo, acryloyl morpholine oligomer, or may be a combination thereof, and the like.

Meanwhile, in order to control the viscosity of the composition before curing and the glass transition temperature after curing, two or more compounds may be mixed and used as the compound having an ethylenically unsaturated bond. For example, as the ethylenically unsaturated compound, a combination of an acrylate compound having an functional group containing at least one of O, N and F atoms and an acryl amide compound is used, or at least one of O, N and F atoms. When using a combination of an acrylate compound and a vinyl pyrrolidone compound having a functional group containing the above, it is possible to improve the workability by lowering the viscosity of the composition before curing, it is possible to implement a high glass transition temperature after curing There is this.

More specifically. The compound having an ethylenically unsaturated bond may be, for example, at least one selected from the group consisting of compounds represented by the following formulas.

Next, the ring-opening polymerizable compound may be an epoxy compound, an oxetane compound, or a combination thereof, but is not limited thereto. For example, an aromatic epoxy compound, a hydrogenated epoxy compound, an alicyclic epoxy compound, It may be an aliphatic epoxy compound, an oxetane compound, or a combination thereof.

Meanwhile, in order to control the viscosity of the composition before curing and the glass transition temperature after curing, two or more compounds may be mixed and used as the ring-opening polymerizable compound. For example, when the alicyclic epoxy compound, the aliphatic epoxy compound, and the oxetane compound are mixed and used as the ring-opening polymerizable compound, the viscosity of the composition before curing can be lowered to improve workability. The advantage is that the glass transition temperature can be realized.

In this case, the aromatic epoxy compound refers to an epoxy compound containing at least one aromatic hydrocarbon ring in the molecule, but is not limited thereto, for example, diglycidyl ether of bisphenol A, digly of bisphenol F Bisphenol-type epoxy resins such as cydyl ether and diglycidyl ether of bisphenol S; Glycidyl ether of tetrahydroxyphenyl methane, Glycidyl ether of tetrahydroxy benzophenone, Novolak-type epoxy resin, such as a phenol novolak epoxy resin, a cresol novolak epoxy resin, and a hydroxy benzaldehyde phenol novolak epoxy resin, And polyfunctional epoxy resins such as epoxidized polyvinylphenol.

In addition, the hydrogenated epoxy compound means an epoxy compound obtained by selectively hydrogenating the aromatic epoxy compound in the presence of a catalyst under pressure, but is not limited thereto, and particularly among the hydrogenated bisphenol A Preference is given to using diglycidyl ether.

In addition, the alicyclic epoxy compound means an epoxy compound in which an epoxy group is 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, vinylcyclohexanedioxide, 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-epoxyprop Lopoxy) norbornene, limonene dioxide, 2,2-bis (3,4-epoxycyclohexyl) propane, dicyclopentadiene dioxide, 1,2-epoxy-6- (2,3-epoxypropoxy ) Hexahydro-4,7-methanoindan, p- (2,3-epoxy) cyclopentylphenyl-2,3-epoxypropylether, 1- (2,3-epoxypropoxy) phenyl-5,6- Epoxyhexahydro-4,7-methanoindan, o- (2,3-epoxy) cyclopentylphenyl-2,3-epoxypropylether), 1,2-bis [5- (1,2-epoxy)- 4,7-hexahydromethanoindanoxyl] ethanecyclopentenylphenylglycidyl ether, methylenebis (3,4-epoxycyclohexane) ethylene glycoldi (3,4-epoxycyclohexylmethyl) ether, ethylenebis ( Ε-caprolactone (1-10 moles) adduct of 3,4-epoxycyclohexanecarboxylate), 3,4-epoxycyclohexane methanol and polyvalent (3-20 values) alcohols (GR, TMP, PE, And esterified compounds of DPE and hexapentaerythritol). Among these, it is preferable to use 3, 4- epoxycyclohexyl methyl-3, 4- epoxy cyclohexane carboxylate from a reactive viewpoint.

Meanwhile, the aliphatic epoxy compound refers to an epoxy compound having an aliphatic chain or an aliphatic ring in a 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 diglycid Dimethyl ether propyl triglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and the like.

On the other hand, the oxetane compound means a compound having at least one oxetanyl group in the molecule, but is not limited thereto, for example, 3-ethyl-3-[(3-ethyloxetan-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 Methoxy] naphthalene, bis [4-{(3-ethyloxetan-3-yl) methoxy} phenyl] methane, bis [2-{(3-ethyloxetan-3-yl) methoxy} phenyl] methane, 2,2-bis [4-{(3-ethyloxetan-3-yl) methoxy} phenyl] propane, novolac type phenol-formal Etherified modified compound with 3-chloromethyl-3-ethyloxetane of hydride, 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-ethyloxetane- 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-ethyl Oxetan-3-yl) methoxy] -2,2,3,3,4,4,5,5-octafluorohexane, etc. are mentioned.

On the other hand, the curable compound as described above is contained in an amount of about 70 to 98.5 parts by weight, preferably about 80 to 98.5 parts by weight, and more preferably about 80 to 90 parts by weight based on the total weight of the composition for polarizing plate protective film. desirable. When the content of the curable compound is less than 70 parts by weight, the viscosity becomes high, and film formation is difficult. When the content of the curable compound is greater than 98.5 parts by weight, the effect of reducing the shrinkage shrinkage is insignificant.

Next, the said (2) non-curable polymer is a component for reducing the cure shrinkage rate of a protective film, and means the polymer which does not contain the functional group which produces hardening reaction like a double bond or an epoxy group. On the other hand, the non-curable polymer used in the present invention is characterized in that it comprises a functional group containing at least one or more of O, N and F atoms in the side chain. As in the present invention, when the above functional groups are included in the side chain of the non-curable polymer, these functional groups form hydrogen bonds with the curable compound, and as a result, the entire composition has a single glass transition temperature. The thermal properties of the protective film can be kept stable.

The functional group containing at least one or more of O, N, and F atoms included in the side chain of the non-curable polymer is not limited thereto, and may be, for example, a hydroxy group, an amine group, an amide group, a urethane group, a carboxyl group, or an anhydride group. It may be at least one selected from the group consisting of an oxazoline group and a fluorine group.

Specific examples of the non-curable polymer that can be used in the present invention include a vinyl alcohol polymer or copolymer, a vinyl acrylic acid polymer or copolymer, a vinylpyrrolidone polymer or copolymer, a vinyl acetate polymer or copolymer, an amide polymer Or a copolymer, a vinylidene fluoride polymer or a copolymer, a urethane polymer or a copolymer, and the like, and each of the above polymers may be used alone or in combination of two or more thereof.

In this case, the vinyl alcohol-based polymer or copolymer may include a repeating unit represented by the following formula (1).

[Formula 1]

The vinyl acrylic acid polymer or copolymer may include a repeating unit represented by Formula 2 below.

[Formula 2]

The vinylpyrrolidone-based polymer or copolymer may include a repeating unit represented by Formula 3 below.

[Formula 3]

The vinyl acetate polymer or copolymer may include a repeating unit represented by the following formula (4).

[Formula 4]

The amide polymer or copolymer may include a repeating unit represented by the following Formula 5.

[Formula 5]

The vinylidene fluoride polymer or copolymer may include a repeating unit represented by the following Formula 6.

[Formula 6]

The urethane-based polymer or copolymer may include a repeating unit represented by the following Chemical Formula 7.

[Formula 7]

In [Formula 7], R and R 'may be each independently alkyl, cycloalkyl or aryl.

On the other hand, the non-curable polymer is preferably contained in an amount of about 1 to 20 parts by weight, preferably about 1 to 15 parts by weight, more preferably about 1 to 10 parts by weight based on the total weight of the composition for polarizing plate protective film. Do. This is because when the content of the non-curable polymer is less than 1 part by weight, the effect of lowering the curing shrinkage ratio is insignificant, and when it exceeds 15 parts by weight, the viscosity becomes high and it is difficult to form a film.

Next, the polymerization initiator is for promoting the curing reaction of the curable compounds, it is good to use a suitable polymerization initiator according to the type of the curable compound used. For example, when the curable compound is a radical curable compound such as an acrylate, a radical initiator may be used, and when the curable compound is a cation curable compound such as an epoxy, a cationic initiator may be used, and a radical initiator and a cationic initiator may be used together. It's okay.

In this case, as the radical initiator, radical initiators generally used in the art may be used without limitation, for example, 1-hydroxy-cyclohexyl-phenyl-ketone (1-Hydroxy-cyclohexyl-phenyl-ketone) , 2-hydroxy-2-methyl-1-phenyl-1-propanone (2-Hydroxy-2-methyl-1-phenyl-1-propanone), 2-hydroxy-1- [4- (2-hydroxy Hydroxyethoxy) phenyl] -2-methyl-1-propanone (2-Hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone), methylbenzoylformate, Oxy-phenyl-acetic acid-2- [2 oxo-2phenyl-acetoxy-ethoxy] -ethyl ester (oxy-phenyl-acetic acid-2- [2-oxo-2-phenyl-acetoxy-ethoxy] -ethyl ester) , Oxy-phenyl-acetic acid-2- [2-hydroxy-ethoxy] -ethyl ester, oxy-phenyl-acetic acid-2- [2-hydroxy-ethoxy] -ethyl ester, alpha-dimethoxy-alpha- Phenylacetophenone (alpha-dimethoxy-alpha-phenylacetophenone), 2-benzyl-2- (dimethylamino) 1- [4- (4-morpholi ) Phenyl] -1-butanone (2-Benzyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl] -1-butanone), 2-methyl-1- [4- (methylthio) Phenyl] -2- (4-morpholinyl) -1-propanone (2-Methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propanone), diphenyl (2 (4,6-trimethylbenzoyl) -phosphine oxide (Diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide), phosphine oxide (Phosphine oxide), phenyl bis (2,4,6-trimethylbenzoyl) (phenyl bis (2,4,6-trimethyl benzoyl)) may be one or more selected from the group consisting of.

On the other hand, the cation initiator may be, for example, those containing sulfonium salt (Sulfonium salt) or iodonium salt (Iodonium salt). The cationic initiator, including sulfonium salt or iodonium salt, is, for example, diphenyl (4-phenylthio) phenylsulfonium hexafluoroantimonate (Diphenyl (4-phenylthio) phenylsulfonium hexafluoroantimonate), diphenyl (4-phenylthio) phenylsulfonium hexafluorophosphate (Diphenyl (4-phenylthio) phenylsulfonium hexafluorophosphate), (phenyl) [4- (2-methylpropyl) phenyl] -iodineium hexafluoro Phosphate ((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) At least one selected from the group consisting of, but is not limited thereto.

On the other hand, the polymerization initiator is preferably contained in an amount of about 0.5 to 10 parts by weight, preferably about 1 to 5 parts by weight, and more preferably about 2 to 4 parts by weight based on the total weight of the composition for polarizing plate protective film. . This is because when the content of the polymerization initiator is less than 0.5 parts by weight, the curing speed may be slowed to hinder the physical properties of the film. When the content of the polymerization initiator is exceeded by 10 parts by weight, the optical properties of the polarizing plate may be impaired due to the unreacted polymerization initiator.

On the other hand, the composition for polarizing plate protective film having the composition described above is about 7% to 13% of the curing shrinkage at 20 ℃. In this case, the cure shrinkage rate means a change rate of the volume before and after curing with respect to the volume before curing of the protective film composition, it can be calculated by the following formula (1).

Equation (1): curing shrinkage (%) = {(V _i -V _f ) / V _i } 100 = {((m / ρ _i )-V _f ) / (m / ρ _i )} 100

In the formula (1), Vi is the volume before curing of the protective film composition, V _f is the volume after curing of the protective film composition, m is the mass of the protective film composition, ρ _i means the density before curing of the protective film composition.

In addition, the composition for the polarizing plate protective film is preferably a glass transition temperature of about 60 ℃ to 200 ℃. When the glass transition temperature of the composition for protective film satisfies the numerical range, a polarizing plate having excellent heat resistance may be manufactured.

In addition, the composition for polarizing plate protective films has a viscosity of about 30 cP to about 500 cP. When the viscosity of the protective film-forming composition satisfies the above range, there is an advantage in that a thin film is easily formed by a general coating process.

When the protective film is formed by using the composition for a protective film as described above, since the curing shrinkage rate of the protective film is low, less curling occurs, and optical properties and thermal properties were also excellent.

On the other hand, the polarizing plate of the present invention may be manufactured by applying a composition for a protective film as described above on at least one surface of the polarizer and then curing to form a protective film. In this case, the coating is a coating method well known in the art, for example, spin coating, bar coating, roll coating, gravure coating Or the like. In addition, the curing may be performed by irradiating active energy rays such as ultraviolet rays, electron beams, and the like.

On the other hand, the polarizer is not particularly limited, and a film made of polyvinyl alcohol (PVA) including a polarizer well known in the art, for example, iodine or dichroic dye, may be used. The polarizer may be prepared by dyeing iodine or dichroic dye on the PVA film, but a method of manufacturing the same is not particularly limited.

On the other hand, the polarizing plate of this invention can further be equipped with the protective film attached to one surface of the said polarizer through the adhesive bond layer as needed. In this case, the protective film is preferably attached to the surface on which the protective film of the polarizer is not formed, but is not necessarily limited thereto.

Meanwhile, the adhesive layer may be formed using various polarizing plate adhesives well known in the art, for example, polyvinyl alcohol adhesive, acrylic adhesive, epoxy adhesive, or urethane adhesive. More specifically, by applying the adhesive as described above to one surface of the protective film or polarizer, and then laminated the polarizer and the protective film, and curing the adhesive by applying heat or active energy rays, etc., the protective film to the polarizer I can attach it.

On the other hand, as the protective film, protective films of various materials generally known in the art, for example, cellulose-based film, polyethylene terephthalate (PET) film, cycloolefin polymer (COP, cycloolefin polymer) ) Films, acrylic films and the like can be used without limitation. Among them, it is particularly preferable to use an acrylic film in view of optical properties, durability, economy and the like.

In this case, the acrylic protective film may contain a (meth) acrylate resin. The film containing the (meth) acrylate-based resin can be obtained, for example, by molding a molding material containing (meth) acrylate-based resin as a main component by extrusion molding.

The acrylic protective film is a film comprising an alkyl (meth) acrylate-based unit and a copolymer comprising a styrene-based unit, and an aromatic resin having a carbonate portion in the main chain, or an alkyl (meth) acrylate-based unit, a styrene-based unit. It may be a film comprising a 3 to 6-membered heterocyclic unit substituted with at least one carbonyl group and a vinyl cyanide unit.

Alternatively, the acrylic protective film may be a film containing a (meth) acrylate resin having an aromatic ring. Examples of the (meth) acrylate-based resin having an aromatic ring include (a) (meth) acrylate-based units comprising (a) one or more (meth) acrylate-based derivatives described in Korean Patent Laid-Open Publication No. 10-2009-0115040; (b) an aromatic unit having a chain having an hydroxy group containing portion and an aromatic moiety; And (c) a styrene unit comprising one or more styrene derivatives. The units (a) to (c) may each be included in the resin composition in the form of a separate copolymer, and two or more units of the units (a) to (c) may be included in the resin composition in the form of one copolymer. have.

Alternatively, the acrylic protective film may be a film including an acrylic resin having a lactone ring structure. As a specific example of (meth) acrylate type resin which has a lactone ring structure, it is the lactone described, for example in Unexamined-Japanese-Patent No. 2000-230016, Unexamined-Japanese-Patent No. 2001-151814, 2002-120326, etc. (Meth) acrylate type resin which has a ring structure is mentioned.

The manufacturing method of the said acrylic protective film is not specifically limited, For example, (meth) acrylate type resin, another polymer, an additive, etc. are fully mixed by arbitrary suitable mixing methods, a thermoplastic resin composition is produced, and this film is then used. It may be produced by molding, or (meth) acrylate-based resin, and other polymers, additives and the like may be prepared in a separate solution and then mixed to form a uniform mixed solution and then film-molded.

The thermoplastic resin composition is prepared by, for example, extrusion kneading the resulting mixture after preblending the film raw material with any suitable mixer such as an omni mixer. In this case, the mixer used for extrusion kneading is not specifically limited, For example, arbitrary appropriate mixers, such as an extruder, such as a single screw extruder and a twin screw extruder, and a pressurized kneader, can be used.

As a method of the said film shaping | molding, arbitrary suitable film shaping | molding methods, such as the solution casting method (solution casting method), the melt extrusion method, the calender method, the compression molding method, are mentioned, for example. Among these film forming methods, a solution cast method (solution casting method) and a melt extrusion method are preferable.

As a solvent used for the said solution casting method (solution casting method), For example, aromatic hydrocarbons, such as benzene, toluene, xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; Esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve and butyl cellosolve; Ethers such as tetrahydrofuran and dioxane; Halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; Dimethylformamide; Dimethyl sulfoxide, etc. are mentioned. These solvents may be used independently or may use 2 or more types together.

As an apparatus for performing the said solution casting method (solution casting method), a drum type casting machine, a band type casting machine, a spin coater, etc. are mentioned, for example. Examples of the melt extrusion method include a T-die method and an inflation method. Molding temperature becomes like this. Preferably it is 150-350 degreeC, More preferably, it is 200-300 degreeC.

When forming a film by the said T die method, a T die can be attached to the front-end | tip of a well-known single screw extruder or a twin screw extruder, the film extruded in film shape can be rolled, and a roll-shaped film can be obtained. Under the present circumstances, you may uniaxially stretch by adjusting the temperature of a winding roll suitably and extending | stretching in an extrusion direction. Moreover, simultaneous biaxial stretching, sequential biaxial stretching, etc. can also be performed by extending | stretching a film in the direction perpendicular | vertical to an extrusion direction.

The acrylic protective film may be any of an unstretched film or a stretched film. In the case of a stretched film, it may be a uniaxial 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 successive biaxially stretched film. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. By mixing another thermoplastic resin, an acryl-type film can suppress an increase of retardation even when extending | stretching, and can maintain optical isotropy.

It is preferable that extending | stretching temperature is a range near the glass transition temperature of the thermoplastic resin composition which is a film raw material, Preferably it is (glass transition temperature -30 degreeC)-(glass transition temperature +100 degreeC), More preferably, it is (glass transition Temperature-20 ° C) to (glass transition temperature + 80 ° C). If the stretching temperature is lower than (glass transition temperature-30 ° C), there is a fear that a sufficient stretching ratio may not be obtained. On the contrary, when extending | stretching temperature exceeds (glass transition temperature + 100 degreeC), there exists a possibility that the flow (flow) of a resin composition may arise and it may not be able to perform stable extending | stretching.

The draw ratio defined by area ratio becomes like this. Preferably it is 1.1-25 times, More preferably, it is 1.3-10 times. If the draw ratio is less than 1.1 times, there is a fear that it does not lead to the improvement of the toughness accompanying stretching. When a draw ratio exceeds 25 times, there exists a possibility that the effect by raising a draw ratio may not be recognized.

The stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min in one direction. If the stretching speed is less than 10% / min, it takes a long time to obtain a sufficient draw ratio, there is a fear that the manufacturing cost increases. When the stretching speed exceeds 20,000% / min, breakage of the stretched film may occur.

The acrylic protective film can be subjected to heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. The heat treatment conditions are not particularly limited and may employ any suitable conditions known in the art.

On the other hand, the acrylic protective film may be subjected to a surface treatment to improve the adhesion if necessary, for example, at least one surface selected from the group consisting of alkali treatment, corona treatment, and plasma treatment on at least one surface of the optical film. Processing can be performed.

Meanwhile, the polarizing plate of the present invention may include an adhesive layer on an upper portion of the protective film, if necessary, for attachment to an optical film such as a display panel or a retardation film.

In this case, the pressure-sensitive adhesive layer may be formed using various pressure-sensitive adhesives well known in the art, and the kind thereof is not particularly limited. For example, the pressure-sensitive adhesive layer may be a rubber pressure sensitive adhesive, an acrylic pressure sensitive adhesive, a silicone pressure sensitive adhesive, a urethane pressure sensitive adhesive, a polyvinyl alcohol pressure sensitive adhesive, a polyvinylpyrrolidone pressure sensitive adhesive, a polyacrylamide pressure sensitive adhesive, a cellulose pressure sensitive adhesive, a vinyl alkyl ether pressure sensitive adhesive, or the like. It can be formed using. Among these, in consideration of transparency, heat resistance and the like, it is particularly preferable to use an acrylic pressure-sensitive adhesive.

On the other hand, the pressure-sensitive adhesive layer may be formed by applying a pressure-sensitive adhesive on the upper portion of the protective film, or may be formed by attaching the pressure-sensitive adhesive sheet prepared by applying the pressure-sensitive adhesive on the release sheet to the upper portion of the protective film.

The thickness of the adhesive layer is not limited thereto, but may be about 1 μm to 50 μm, preferably about 5 μm to 40 μm, and more preferably about 10 μm to 30 μm.

The polarizing plate of the present invention as described above can be usefully applied to an optical device such as a liquid crystal display device. The optical device may be, for example, a liquid crystal display including a liquid crystal panel and polarizing plates provided on both surfaces of the liquid crystal panel, and at least one of the polarizing plates may be a polarizing plate according to the present invention. At this time, the type of liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, a panel of a passive matrix type such as, but not limited to, a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferrolectic (F) type, or a polymer dispersed (PD) type; Active matrix panels such as two-terminal or three-terminal; All known panels, such as an In Plane Switching (IPS) panel and a Vertical Alignment (VA) panel, can be applied. In addition, other configurations constituting the liquid crystal display device, for example, types of upper and lower substrates (eg, color filter substrates or array substrates) are not particularly limited, and configurations known in the art may be employed without limitation. Can be.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

실시예 1 - 보호막용 조성물 AExample 1-Composition A for Protective Film

47 g of 2-hydroxyethyl acrylate, 45 g of normal vinylpyrrolidone, 5 g of polyvinyl alcohol resin (Japanese synthetic Gohsefimer Z 100), and 3 g of Igarcure 819 were mixed and then heated to 90 ° C. to prepare a protective film composition A.

실시예 2 - 보호막용 조성물 BExample 2-Composition B for Protective Film

47 g of 2-hydroxyethyl acrylate, 30 g of dimethyl acrylamide (DMAA), 20 g of polyvinylpyrrolidone (IS-15 K-15), and 3 g of Igarcure 819 were mixed and heated to 90 ° C. to form a protective film composition. B was prepared.

실시예 3 - 보호막용 조성물 CExample 3-Composition C for Protective Film

47 g of 2-hydroxyethyl acrylate, 40 g of DMAA, 10 g of Polyurethane (Curant Paint Co., Ltd. CPU0320), and 3 g of Igarcure 819 were mixed and heated to 90 ° C to prepare a protective film composition C.

실시예 4 - 보호막용 조성물 DExample 4-Composition D for Protective Film

Low-humidity environment (humidity) after mixing 47 g of 2-hydroxyethyl acrylate, 40 g of DMAA, 10 g of polyacrylic acid resin (Sigma-Aldrich company catalog no. 323667) and 3 g of Igarcure 819 20% or less) was heated to 90 ℃ to prepare a composition D for a protective film.

실시예 5 - 보호막용 조성물 EExample 5-Composition E for Protective Film

Daicel Celoxide 2021P (3'-4'-Epoxycyclohexane) methyl 3'-4'-epoxycyclohexyl-carboxylate) 20g, Cyclohexanedimethanol Diglycidyl Ether 20g, Toagosei Corporation oxt-221 (3- 45 g of ethyl-3-{[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane), 10 g of polyacrylic acid resin (Sigma-Aldrich company catalog no. 323667), 5 g of Dow chemical company UVI-6992 Triarylsulfonium hexafluorophosphate It heated to 60 degreeC and produced the composition E for protective films.

비교예 1 - 보호막용 조성물 FComparative Example 1-Composition F for Protective Film

52 g of 2-hydroxyethyl acrylate, 45 g of normal vinylpyrrolidone, and 3 g of Igarcure 754 were mixed to prepare a composition F for a protective film.

비교예 2 - 보호막용 조성물 GComparative Example 2-Composition G for Protective Film

47 g of 2-hydroxyethyl acrylate, 40 g of normal vinylpyrrolidone, 10 g of polymethyl methacrylate resin (LG MMA HP-202), and 3 g of Igarcure 754 were mixed and then heated to 90 ° C. to prepare a protective film composition G. It was.

실험예 1Experimental Example 1

The curing shrinkage ratio, glass transition temperature, and viscosity at 20 ° C. of the protective film compositions A to G prepared according to Examples 1 to 5 and Comparative Examples 1 to 2 were measured by the following methods. The measurement results are shown in the following [Table 1].

(1) Curing shrinkage rate: The volume (Vi) of 1 g of the protective film compositions A to G prepared in Examples 1 to 5 and Comparative Examples 1 to 2 was measured using an automatic gas pycnometer, respectively. Then, each of the protective film compositions is applied on a release PET film and cured, and then peeled off from the PET film. The volume (Vf) of the peeled protective film was measured using a fully automatic gas specific gravity, and then the cure shrinkage rate was calculated using Equation (1).

(2) Glass transition temperature: The thin film of hardened protective film was taken and measured by DCS (Differential Scanning Calorimetry) of Mettler Toledo. The measurement temperature range was -30 ° C to 200 ° C twice at 10 ° C per minute, and the measured glass transition temperature was the glass transition temperature at the second scan.

(3) Viscosity: The viscosity of compositions A to G for protective films prepared in Examples 1 to 5 and Comparative Examples 1 to 2 was measured at 25 ° C. using Viscometer TV-22 (TOKI SANGYO).

Table 1

division	Hardening Shrinkage (%)	Glass transition temperature (℃)	Viscosity (cP)
Example 1	12.3	80 ℃	250
Example 2	9.8	78 ℃	120
Example 3	11.5	76 ℃	40
Example 4	11.8	88 ℃	70
Example 5	6.8	103 ℃	55
Comparative Example 1	14.6	81 ℃	10
Comparative Example 2	13.4	7 ℃ and 99 ℃	100-600 (not consistently measured)

As shown in Table 1, the compositions of Comparative Examples 1 and 2 not only have a higher curing shrinkage ratio than the compositions of Examples 1 to 5, but the compositions of Comparative Example 1 have very low viscosities, which may cause difficulties in film formation. It can be seen that the composition of Comparative Example 2 has a double Tg value and is not suitable for producing a polarizing plate having excellent heat resistance.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and changes can be made without departing from the technical spirit of the present invention described in the claims. It will be obvious to those of ordinary skill in the field.

Claims

A polarizer and a protective film formed on at least one surface of the polarizer,

The protective film may include at least one curable compound selected from the group consisting of a compound having an ethylenically unsaturated bond with a functional group including at least one of O, N and F atoms and a ring-opening polymerizable compound;

An uncured polymer comprising a functional group comprising at least one of O, N and F atoms in the side chain; And

The polarizing plate formed by the composition for polarizing plate protective films containing a polymerization initiator.
The method of claim 1,

The composition for polarizing plate protective film,

70 parts by weight to 98.5 parts by weight of at least one curable compound selected from the group consisting of a compound having at least one or more O, N and F atoms and a compound having an ethylenically unsaturated bond and a ring-opening polymerizable compound,

1 part by weight to 20 parts by weight of an uncured polymer comprising a functional group containing at least one of O, N and F atoms in the side chain, and

Polarizing plate containing 0.5 to 10 parts by weight of the polymerization initiator.
The method of claim 1,

The functional group containing at least one of the O, N and F atoms is at least one member selected from the group consisting of hydroxy group, amine group, amide group, urethane group, carboxyl group, acid anhydride group, oxazoline group and fluorine group.
The method of claim 1,

The compound having a functional group and an ethylenically unsaturated bond containing at least one or more of the O, N and F atoms is an acrylic compound, a vinyl compound or a combination thereof.
The method of claim 1,

The compound having a functional group and an ethylenically unsaturated bond containing at least one or more of the O, N and F atoms is at least one member selected from the group consisting of compounds represented by the following formula.
The method of claim 1,

The ring-opening polymerizable compound is an epoxy compound, an oxetane compound or a combination thereof.
The method of claim 1,

The non-curable polymer including a functional group containing at least one of O, N and F atoms in the side chain may be a vinyl alcohol polymer or copolymer, a vinyl acrylic acid polymer or copolymer, a vinylpyrrolidone polymer or copolymer, vinyl At least one polarizing plate selected from the group consisting of acetate polymers or copolymers, amide polymers or copolymers, vinylidene fluoride polymers or copolymers, and urethane polymers or copolymers.
The method of claim 1,

The polymerization initiator is a cationic polymerization initiator, a radical polymerization initiator or a combination thereof.
The method of claim 1,

The polarizing plate protective film composition is a polarizing plate of 7% to 13% cure shrinkage at 20 ℃.
The method of claim 1,

The polarizing plate protective film composition has a glass transition temperature of 60 ℃ to 200 ℃ polarizing plate.
The method of claim 1,

The composition for polarizing plate protective film is a polarizing plate having a viscosity of 30cP to 500cP.
The method of claim 1,

The polarizing plate with a protective film attached to the opposite side of the surface on which the protective film of the polarizer is formed via an adhesive layer.
The method of claim 12,

The protective film is a cellulose film, polyethylene terephthalate (PET, polyethylene terephthalate) film, cycloolefin polymer (COP, cycloolefin polymer) film or an acrylic film polarizing plate.
The method of claim 1,

Polarizing plate further comprising an adhesive layer on the protective film.
A display device comprising the polarizing plate of claim 1.