KR101854507B1 - Polarizing plate and optical display apparatus comprising the same - Google Patents

Abstract

A polarizer, an optical film formed below the polarizer, and an adhesive film for a polarizing plate formed below the optical film, wherein the swelling degree of the polarizing plate is 200% or less in Formula 1, and the polarizing plate- (Meth) acrylate having an unsubstituted alkyl group and 5 to 30% by weight of a (meth) acrylate having an unsubstituted alkyl group, wherein the optical film comprises a cyclic polyolefin resin, a polycarbonate resin, And a polarizing plate and an optical display device including the polarizing plate are provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate and an optical display device including the polarizing plate.

The present invention relates to a polarizing plate and an optical display device including the same.

The liquid crystal display device includes a liquid crystal panel and a polarizing plate attached to both sides of the liquid crystal panel. The polarizer includes a polarizer and a protective film formed on one or both sides of the polarizer. The polarizing plate is attached to the liquid crystal panel by an adhesive film for a polarizing plate. The pressure sensitive adhesive film for a polarizing plate is formed of a pressure sensitive adhesive composition for a polarizing plate.

A polycarbonate-based, cyclic polyolefin-based or (meth) acrylic-based protective film often used as a retardation film in a protective film may cause cracking during solvent contact and heat treatment during the assembly process of an image display device. The polarizing plate including the cracked protective film may cause a light leakage phenomenon at the crack occurrence site and the protective film may not block the influence of the polarizer on the external environment and the reliability of the polarizing plate may be deteriorated. In addition, since the original retardation providing function as a retardation film can not be attained, the polarizing plate image quality may deteriorate. In recent years, with the polarizing plate becoming thinner, the protective film is also thinned, and there is a great possibility that cracks will occur due to handling problems and solvents constituting the adhesive and the pressure-sensitive adhesive.

The background art of the present invention is described in Japanese Laid-Open Patent Publication No. 2014-032270.

A problem to be solved by the present invention is to provide a polarizing plate capable of suppressing cracking of an optical film by an organic solvent.

Another problem to be solved by the present invention is to provide a polarizing plate excellent in transparency and thinned.

Another problem to be solved by the present invention is to provide a polarizer excellent in endurance reliability.

Another object of the present invention is to provide a polarizing plate having high adhesion to a hydrophobic optical film.

The polarizing plate of the present invention comprises a polarizer, an optical film formed below the polarizer, and an adhesive film for a polarizing plate formed below the optical film, wherein the polarizing plate adhesive film has a degree of swelling of 200%

<Formula 1>

Swelling degree = (B - A) /0.2 x 100

(In the above formula 1, A and B are as defined in the detailed description of the present invention)

Wherein the adhesive film for a polarizing plate comprises a (meth) acrylic copolymer of a monomer mixture comprising 5 to 30% by weight of a (meth) acrylate having an unsubstituted alkyl group of C11 to C20, Based resin, a polyolefin-based resin, a polycarbonate-based resin, and a (meth) acrylic-based resin.

The optical display device of the present invention may comprise the above-mentioned pressure sensitive adhesive film for a polarizing plate.

The present invention provides a polarizing plate in which cracking due to an organic solvent of an optical film is suppressed.

The present invention provides a polarizing plate excellent in transparency and thinned.

The present invention provides a polarizing plate having excellent endurance reliability.

The present invention provides a polarizing plate having high adhesion to a hydrophobic optical film.

1 is a sectional view of a polarizing plate of an embodiment of the present invention.
2 is a cross-sectional view of a polarizing plate of another embodiment of the present invention.
3 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

It should be noted that the terms "upper" and "lower" in the present specification are based on the drawings and are not necessarily fixed to the upper and lower portions, .

In the present specification, "adhesive film for polarizing plate" and "pressure-sensitive adhesive composition for polarizing plate" may be referred to as "adhesive film" and "pressure-sensitive adhesive composition", respectively. As used herein, "(meth) acrylic" means acrylic and / or methacrylic.

In the present specification, the "degree of swelling" of the pressure-sensitive adhesive film is obtained by placing 0.2 g of the pressure-sensitive adhesive film in a wire net (weight: A, unit: g, 200 mesh), placing the wire net containing the pressure-sensitive adhesive film in a 250 ml bottle, The weight of the whole wire netting containing the adhesive film after leaving the wire net containing the adhesive film at 25 ° C for 30 minutes and leaving it at 25 ° C for 3 days so that the adhesive film contained in the wire net is completely immersed, g), and is calculated by the following formula 1:

<Formula 1>

Swelling degree = (B - A) /0.2 x 100

The organic solvent may include at least one of toluene, methyl ethyl ketone, and ethyl acetate. The pressure-sensitive adhesive film is produced by coating a pressure-sensitive adhesive composition on a release film (for example, a polyethylene terephthalate (PET) film) and aging the film at 35 ° C and 45% RH for 2 days to produce an adhesive film having a thickness of 25 μm, will be.

In the present specification, the "modulus" of the pressure-sensitive adhesive film is a storage modulus, and a plurality of pressure-sensitive adhesive films having a thickness of 25 占 퐉 are laminated and cut to produce circular specimens having a thickness of 1 mm and a diameter of 8 mm. The prepared specimens are Physica MCR501 Means a value at 25 ° C when evaluated at a shear rate of 1 rad / sec and 5% strain while heating at a rate of 10 ° C / min from 25 ° C to 120 ° C on a disk having a diameter of 8 mm using a stirrer. At this time, the pressure-sensitive adhesive film is prepared by coating a pressure-sensitive adhesive composition on a release film (for example, PET film) and aging at 35 캜 and 45% RH for 2 days to produce a pressure-sensitive adhesive film having a thickness of 25 탆 and releasing it from the release film.

In the present specification, "in-plane retardation (Re)" of the optical film is represented by the following formula (2), and "thickness direction retardation (Rth)

<Formula 2>

Re = (nx - ny) xd

<Formula 3>

Rth = ((nx + ny) / 2 - nz) xd

(Nx, ny, and nz are refractive indexes in the x-axis, y-axis, and z-axis directions of the optical film at a wavelength of 550 nm, respectively, and d is the thickness (unit: nm) of the optical film).

As used herein, the term "optical film" may mean a protective film or a retardation film.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 1, the polarizing plate 100 according to the present embodiment may include a polarizing plate adhesive film 110, a first protective film 120, a polarizer 130, and a second protective film 140.

The degree of swelling of the adhesive film 110 for a polarizing plate may be 200% or less.

The degree of swelling is the degree to which the polarizing plate adhesive film absorbs organic solvents and the like. The degree of swelling of the adhesive film for a polarizing plate having a low swelling degree is low enough to absorb and / or absorb an organic solvent and the like, so that the first protective film 120 can be prevented from being cracked by an organic solvent or the like. Specifically, the swelling degree of the polarizing plate adhesive film may be from 50% to 200%. Specifically, the organic solvent may be toluene, ethyl acetate, methyl ethyl ketone or the like, but is not limited thereto. Therefore, even if the polarizing plate 100 is exposed to organic solvent contact and heat treatment, the occurrence of cracks in the first protective film 120 can be reduced. It is possible to suppress the occurrence of cracks even when applying the thin first protective film 120, which is easy to generate cracks, to make the polarizing plate thinner, and the adhesive film for the polarizing plate can suppress the cracks caused by the organic solvent of the first protective film 120, Endurance reliability can also be enhanced.

Hereinafter, the polarizing plate adhesive film 110 will be described in detail.

The adhesive film 110 for a polarizing plate may be formed on the first protective film 120 to adhere the polarizing plate 100 to an optical element such as a panel for a liquid crystal display device.

The polarizing plate adhesive film 110 is directly formed on the first protective film 120. The "directly formed" means that no adhesive layer and / or adhesive layer is interposed between the polarizing plate adhesive film 110 and the first protective film 120. Even so, the degree of swelling of the polarizing plate adhesive film 110 is less than 200%, thereby preventing the first protective film 120 from being cracked by an organic solvent or the like.

The pressure-sensitive adhesive film 110 for a polarizing plate may have a modulus of 0.5 MPa or more, specifically 0.5 MPa to 10 MPa, more specifically 0.5 MPa to 1 MPa at 25 占 폚. In the above range, the cohesive force of the pressure-sensitive adhesive film is high, so that the pressure-sensitive adhesive film can absorb less organic solvents and the like, can suppress cracking caused by the organic solvent and the like of the protective film, and can exhibit excellent processability.

The thickness of the adhesive film 110 for a polarizing plate may be 30 占 퐉 or less, specifically 5 占 퐉 to 30 占 퐉. In the above range, it can be used in an optical display device.

The (meth) acrylic adhesive resin for a polarizing plate is formed from a pressure sensitive adhesive composition for a polarizing plate comprising a (meth) acrylic adhesive resin and a curing agent, and the (meth) acrylic adhesive resin comprises a (meth) acrylate 5 having an unsubstituted alkyl group of C11 to C20 To 30% by weight, and the curing agent may be included in an amount of 10 to 25 parts by weight based on 100 parts by weight of the (meth) acrylic adhesive resin. In the above range, it has a good cohesive strength and can increase the degree of crosslinking of the pressure-sensitive adhesive film, so that the swelling degree can be lowered and the durability can be secured.

The pressure-sensitive adhesive film for a polarizing plate can be produced by coating the pressure-sensitive adhesive composition for a polarizing plate to a predetermined thickness, drying it, and then aging at a constant temperature and humidity of 25 ° C to 50 ° C and a relative humidity of 30% to 60%.

Hereinafter, a pressure-sensitive adhesive composition for a polarizing plate according to an embodiment of the present invention will be described.

The pressure-sensitive adhesive composition for a polarizing plate according to the present embodiment contains 5 to 30% by weight, specifically 10 to 30% by weight, more specifically 15 to 30% by weight, of (meth) acrylate having an unsubstituted alkyl group of C11 to C20 (Meth) acryl-based copolymer polymerized with a monomer mixture containing about 25% by weight of the (meth) acrylic copolymer. Within this range, the pressure-sensitive adhesive film may contain a suitable amount of a hydrophobic alkyl group to lower the degree of swelling of the pressure-sensitive adhesive film, and durability reliability may also be ensured.

The (meth) acrylate having an unsubstituted alkyl group of C11 to C20 is a (meth) acrylate having a linear C11 to C20 unsubstituted linear alkyl group such as lauryl (meth) acrylate, tri (Meth) acrylate, nonadecyl (meth) acrylate, myristyl (meth) acrylate, myristyl (meth) acrylate, pentadecyl (meth) acrylate, cetyl can do. These can give the effect of suppressing the cracking of the organic solvent to the first protective film 120. [

(Meth) acrylic copolymers include (meth) acrylates having C11 to C20 unsubstituted alkyl groups; And (meth) acrylates having C1 to C10 unsubstituted alkyl groups, monomers having (meth) acrylate having a hydroxyl group and monomers having a carboxylic acid group. Therefore, the polarizing plate adhesive film 110 can secure a degree of swelling of 200% or less, and can have good adhesion to the first protective film 120.

The (meth) acrylate having an unsubstituted alkyl group of C1 to C10 is at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, (Meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, iso-octyl (meth) acrylate, nonyl These may be included singly or in combination of two or more. The (meth) acrylate having an unsubstituted alkyl group of C1 to C10 may be contained in the monomer mixture in an amount of 65% by weight to 85% by weight, specifically 70% by weight to 80% by weight. Within this range, it is possible to provide the adhesive film with mechanical strength and have excellent adhesive properties.

The (meth) acrylate having a hydroxyl group may include (meth) acrylate having at least one hydroxyl group, a C1 to C20 alkyl group, a C3 to C10 cycloalkyl group or a C6 to C20 aryl group. Specifically, the (meth) acrylate having a hydroxyl group is preferably selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, At least one of mono (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclopentyl (meth) acrylate and 4-hydroxycyclohexyl (meth) . These may be included singly or in combination of two or more. The (meth) acrylate having a hydroxyl group may be contained in the monomer mixture in an amount of 0.1 wt% to 5 wt%, specifically 0.5 wt% to 2.5 wt%. Within the above range, the degree of crosslinking of the pressure-sensitive adhesive film may be high and the adhesive force of the pressure-sensitive adhesive film to the protective film may be good.

The monomer having a carboxylic acid group may be at least one monomer selected from the group consisting of (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, itaconic acid, , Maleic anhydride, and the like. These may be included singly or in combination of two or more. The (meth) acrylate having a carboxylic acid group may be contained in the monomer mixture in an amount of 0.1 wt% to 5 wt%, specifically, 1.5 wt% to 2.5 wt%. Within the above range, the degree of crosslinking of the pressure-sensitive adhesive film may be high and the adhesive force of the pressure-sensitive adhesive film to the protective film may be good.

The monomer having a carboxylic acid group may be contained in an excessive amount in a monomer mixture to (meth) acrylate having a hydroxyl group. For example, the weight ratio of the monomer content having a carboxylic acid group to the (meth) acrylate having a hydroxyl group in the monomer mixture may be 1.5 to 5, specifically 1.5 to 3. Within the above range, adhesion to hydrophobic protective film can be ensured.

(Meth) acrylic copolymer may have a weight average molecular weight (Mw) of 1.3 million or less, specifically from 900 to 1.3 million. Within the above range, the durability of the adhesive film can be excellent. The weight average molecular weight may be a value obtained by converting the polystyrene in the gel permeation chromatography method. (Meth) acrylic copolymer may have a glass transition temperature of -80 ° C to -10 ° C, specifically -75 ° C to -20 ° C. Within the above range, it is possible to have an adhesive property with excellent wettability. The (meth) acrylic copolymer may have a polydispersity of 2.0 to 10.0, more specifically 3.0 to 7.0. Within the above range, durability can be secured at a high temperature. The (meth) acrylic copolymer may have an acid value of 5.0 mgKOH / g or less, more specifically 0.1 mgKOH / g to 3.0 mgKOH / g. Within this range, it is possible to realize a corrosion preventing effect directly or indirectly on the adherend.

The (meth) acrylic copolymer may be prepared by polymerizing a monomer mixture by a conventional polymerization method. The polymerization method may include conventional methods known to those skilled in the art. For example, the (meth) acrylic copolymer can be prepared by adding an initiator to a monomer mixture, followed by conventional copolymerization, such as suspension polymerization, emulsion polymerization, solution polymerization and the like. The polymerization temperature may be 65 占 폚 to 70 占 폚, and the polymerization time may be 6 hours to 8 hours. The initiator may be an azo-based polymerization initiator; And / or peroxides such as benzoyl peroxide or acetyl peroxide, and the like.

The pressure-sensitive adhesive composition for a polarizing plate according to this embodiment may include a curing agent. The curing agent may be contained in an amount of 10 parts by weight to 25 parts by weight, specifically 15 parts by weight to 20 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer. Within the above range, the degree of crosslinking of the pressure-sensitive adhesive film can be increased and the swelling degree can be lowered.

The curing agent is a polyfunctional curing agent and may include at least one of an isocyanate curing agent, a metal chelating curing agent, an epoxy curing agent, an amine curing agent and a carbodiimide curing agent. Specifically, the curing agent contains a mixture of an isocyanate-based curing agent and a metal chelate-based curing agent, whereby the aging time can be shortened while the degree of curing is increased, and the degree of swelling can be reduced. More specifically, the isocyanate-based curing agent is contained in an excess amount relative to the metal chelate-based curing agent, and the isocyanate-based curing agent may include 9 to 20 parts by weight and the metal chelate-based curing agent may be included in a mixture of 0.1 to 5 parts by weight.

The isocyanate-based curing agent may include an isocyanate-based curing agent having two or more functional groups, such as trifunctional or hexafunctional, and at this time, the modulus and the gel fraction of the adhesive film can be easily increased. Specifically, the isocyanate-based curing agent is a trifunctional isocyanate curing agent including trifunctional trimethylolpropane-modified toluene diisocyanate adduct, trifunctional toluene diisocyanate trimer, trimethylolpropane-modified xylene diisocyanate adduct, etc., 6 Functionalized trimethylolpropane-modified toluene diisocyanate, and hexafunctional isocyanurate-modified toluene diisocyanate. These may be included singly or in combination of two or more.

The metal chelate-based curing agent may include aluminum, zirconium, titanium, cobalt and the like, more specifically, aluminum. The metal chelating curing agent is selected from the group consisting of acetylacetonate aluminate, aluminum tris (acetylacetonate), aluminum tris (ethyl acetoacetate, aluminum bis (ethylacetoacetate), zirconium tris (acetylacetonate), cobalt tris But is not limited thereto.

The epoxy-based curing agent is selected from the group consisting of bisphenol A epichlorohydrin type epoxy resin, ethyleneglycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol Diglycidyl ether, diglycidyl ether, trimethylol propane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, 1,3- Bis (N, N-diglycidylaminomethyl) benzene, N, N, N ', N'-tetraglycidyl- m-xylylenediamine. &lt; / RTI &gt;

The pressure sensitive adhesive composition for a polarizing plate according to this embodiment may further include a silane coupling agent. Silane coupling agent The silane coupling agent can increase the adhesion of the adhesive film to an adherend such as glass.

The silane coupling agent may comprise conventional silane coupling agents known to those skilled in the art. For example, the silane coupling agent may be 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclo Hexyl) ethyl trimethoxysilane and the like; A polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and (meth) acryloxypropyltrimethoxysilane; Containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane. ; And 3-chloropropyltrimethoxysilane, and the like, but are not limited thereto.

The silane coupling agent may be contained in an amount of 0.05 to 5 parts by weight, specifically 0.05 to 1 part by weight, based on 100 parts by weight of the (meth) acrylic copolymer. Within the above range, the durability reliability can be ensured with excellent adhesive performance.

The pressure-sensitive adhesive composition for a polarizing plate according to this embodiment may further include usual additives. The additive may include an antistatic agent, an ultraviolet absorber, an antioxidant, a tackifier, a plasticizer, and the like.

The pressure-sensitive adhesive composition for a polarizing plate may have a viscosity of 500 cPs to 2,500 cPs at 25 캜. Within the above range, the thickness of the adhesive film can be easily adjusted, there is no unevenness in the adhesive film, and the coated surface can have a uniform effect.

Hereinafter, the first protective film 120 will be described.

The first protective film 120 may be formed on the polarizer 130 and the adhesive film 110 for the polarizer so as to protect the polarizer 130. [ The first protective film 120 may be a film formed of a resin that is optically transparent and susceptible to cracking upon contact with an organic solvent or the like. For example, the first protective film 120 may be a film formed of at least one of a cyclic polyolefin resin including a cyclic polyolefin and the like, a polycarbonate resin, and a (meth) acrylic resin. For example, the first protective film 120 may be a film that is cracked when heat-treated at 170 ° C to 220 ° C while exposed to an organic solvent (such as ethyl acetate, toluene, methyl ethyl ketone, etc.).

The first protective film 120 may be a hydrophobic film and may have a water contact angle of 100 ° to 120 ° at 25 ° C. The first protective film 120 may be a film having been subjected to a surface treatment such as a primer or a corona treatment in order to increase the bonding strength with the adhesive film 110. The pressure-sensitive adhesive film for a polarizing plate of the present invention also has good adhesion to a first hydrophobic protective film.

The first protective film 120 can improve the viewing angle and the image quality of the polarizing plate with a retardation film having a predetermined range of retardation. Specifically, the first protective film 120 may have a Re of 0 nm to 200 nm and an Rth of -200 nm to 200 nm. In the above range, image quality can be improved when a polarizing plate is applied. In the case of the vertical alignment (VA) mode, the Re value is preferably 30 nm to 80 nm, the Rth value is preferably 100 nm to 200 nm, and in the IPS (in-plane switching) mode, Re may be 0 nm to 20 nm , And Rth is preferably -10 nm to 10 nm.

The first protective film 120 may have a thickness of 5 占 퐉 to 80 占 퐉, for example, 20 占 퐉 to 60 占 퐉, more specifically, 40 占 퐉 to 60 占 퐉. And can be used in an optical display device in the above range.

Hereinafter, the polarizer 130 will be described.

The polarizer 130 may polarize external light or internal light. The polarizer 130 may include a polyvinyl alcohol polarizer in which iodine or the like is stained on a polyvinyl alcohol film, and a polyene polarizer produced by dehydrating a polyvinyl alcohol film. For example, a polyvinyl alcohol polarizer is prepared by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching it in a certain direction. Specifically, it is produced through a swelling process, a dyeing process, and a stretching process. Methods of performing each step are commonly known to those skilled in the art. The thickness of the polarizer 130 may be 5 占 퐉 to 50 占 퐉. And can be used in an optical display device in the above range.

Hereinafter, the second protective film 140 will be described.

A second protective film 140 may be formed on the polarizer 130 to protect the polarizer 130. The second protective film 140 may include a film formed of the same or different resin as the first protective film 120. Specifically, the second protective film 140 may be made of a polyester type, triacetyl cellulose or the like including a cyclic polyolefin type, a poly (meth) acrylate type, a polycarbonate type, a polyethylene terephthalate (PET) Based resin may be formed of at least one of a polyester resin, an ester resin, a polyether sulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a polyolefin resin, a polyarylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, have. The thickness of the second protective film 140 may be equal to or different from that of the first protective film 120.

An adhesive layer may be formed between the polarizer 130 and the first protective film 120 and between the polarizer 130 and the second protective film 140, though not shown in FIG. The adhesive for the polarizing plate may include an aqueous adhesive, a pressure sensitive adhesive, and an ultraviolet curable adhesive.

Hereinafter, a polarizing plate of another embodiment of the present invention will be described with reference to FIG.

2, the polarizer 200 of the present embodiment includes a first adhesive film 110a, a first retardation film 150, a second adhesive film 110b, a second retardation film 160, and a polarizer 130 Can be sequentially stacked. The first adhesive film 110a and the second adhesive film 110b may include the above-described adhesive film for a polarizing plate of the present invention.

The first retardation film 150 and the second retardation film 160 may each be a film formed of at least one of a cyclic polyolefin resin including a cyclic polyolefin and the like, a polycarbonate resin, and a (meth) acrylic resin . Therefore, even when the first and second retardation films 150 and 160 are exposed to the organic solvent contact and the heat treatment, the occurrence of cracks can be reduced.

The thicknesses of the first retardation film 150 and the second retardation film 160 may be 5 탆 to 80 탆, for example, 20 탆 to 60 탆. In the above range, it can be used for a polarizing plate.

2 shows the case where both the first adhesive film 110a and the second adhesive film 110b are the polarizing plate adhesive film of the present invention. However, when the first adhesive film 110a and the second adhesive film 110b are used, May be included in the scope of the present invention when any one of them is the adhesive film for a polarizing plate of the present invention. Although not shown in FIG. 2, a conventional protective film or a retardation film may be laminated on the upper surface of the polarizer. In FIG. 2, the first retardation film and the second retardation film have different thickness, material, and phase difference, but the same case may be included in the scope of the present invention. Further, although not shown in FIG. 2, an adhesive layer or an adhesive layer may be formed between the polarizer and the second retardation film.

The optical display device of one embodiment of the present invention may include the polarizing plate of the present invention. For example, the optical display device may include a liquid crystal display device, an organic light emitting display device, but is not limited thereto.

3 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention. 3, a liquid crystal display 300 according to an exemplary embodiment of the present invention includes a liquid crystal display panel 310, a first polarizer 320 formed on the upper surface of the liquid crystal display panel 310, A second polarizer 330 formed on the lower surface and a backlight unit 340 formed on the lower portion of the second polarizer 330. One or more of the first polarizer 320 and the second polarizer 330 may be used in the present invention Examples may include polarizing plates.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Example 1

77 parts by weight of n-butyl acrylate (BA), 20 parts by weight of lauryl acrylate (LA), 2 parts by weight of acrylic acid (AA), and 10 parts by weight of norbornene were added to a 1 L reactor equipped with a cooling device, And 100 parts by weight of a monomer mixture comprising 1 part by weight of 2-hydroxyethyl methacrylate (2-HEMA). To the monomer mixture were added 60 parts by weight of ethyl acetate as a solvent and 25 parts by weight of methyl ethyl ketone. The monomer mixture was nitrogen purged at 65 占 폚 for 30 minutes and 0.04 part by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was diluted in 2 parts by weight of ethyl acetate. The temperature of the reactor was maintained at 65 DEG C, and the reaction was carried out for 6 hours and further reacted at 70 DEG C for 2 hours. After completion of the reaction, 130 parts by weight of ethyl acetate was added to prepare a methacrylic copolymer solution.

20 parts by weight of methyl ethyl ketone as a solvent was added to 100 parts by weight of a methacrylic copolymer, and 12 parts by weight of an isocyanate curing agent L-45 (Soken), 3.1 parts by weight of a metal chelate crosslinking agent (acetylacetonate aluminate) And 0.08 part by weight of coupling agent KBE-403 (Shin-Yatsu) were added to prepare a pressure-sensitive adhesive composition.

Example 2

A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the monomer mixture was changed as shown in Table 1 below.

Comparative Examples 1 to 4

A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the content of the monomer mixture and the curing agent was changed as shown in Table 1 below.

The properties of the polarizing plate including the pressure-sensitive adhesive composition of Examples and Comparative Examples and the pressure-sensitive adhesive film for a polarizing plate prepared therefrom were evaluated in Table 1 below.

Example Comparative Example One 2 One 2 3 4 BA (parts by weight) 77 77 77 77 97 77 LA (parts by weight) 20 - 20 - - - SA ^* (parts by weight) - 20 - - - - EHA ^* (parts by weight) - - - 20 - - MA ^* (parts by weight) - - - - - 20 AA (parts by weight) 2 2 2 2 2 2 2-HEMA (parts by weight) One One One One One One Total (parts by weight) 100 100 100 100 100 100 Isocyanate-based curing agent (parts by weight) 12 12 8 8 12 12 Metal chelate-based curing agent (parts by weight) 3.1 3.1 3.1 3.1 3.1 3.1 Silane coupling agent (parts by weight) 0.08 0.08 0.08 0.08 0.08 0.08 Modulus (MPa) 0.57 0.62 0.32 0.43 0.77 0.89 Swelling (%) 180 150 260 370 490 760 Crack occurrence ○ ○ △ △ × × Endurance reliability ○ ○ ○ ○ △ ×

* In Table 1, SA denotes stearyl acrylate, EHA denotes ethylhexyl acrylate, and MA denotes methyl acrylate.

As shown in Table 1, the polarizing plate of the embodiment of the present invention can suppress the occurrence of cracks in the retardation film and enhance the endurance reliability of the polarizing plate.

On the other hand, the polarizing plates of Comparative Examples 1 to 4 contained a polarizing plate adhesive film having a degree of swelling of more than 200%, resulting in a large number of cracks, or poor durability reliability.

(1) Modulus of pressure-sensitive adhesive film: The pressure-sensitive adhesive composition of Examples and Comparative Examples was coated on a polyethylene terephthalate film and aged at 35 캜 and 45% relative humidity for 2 days to prepare a pressure-sensitive adhesive film having a thickness of 25 탆, A plurality of the obtained adhesive films were laminated and cut to prepare circular specimens having a thickness of 1 mm and a diameter of 8 mm. The prepared specimens were subjected to measurement at 25 DEG C on a disc having a diameter of 8 mm using Physica MCR501 (Anton paar) To a temperature of 25 ° C when the shear rate is measured at a rate of 1 rad / sec and 5% strain while heating at 120 ° C at a heating rate of 10 ° C / min.

(2) Swelling degree: 0.2 g of the pressure-sensitive adhesive composition of Examples and Comparative Examples was coated on a release film and aged at 35 캜 and 45% RH for 2 days to prepare 0.2 g of an adhesive film having a thickness of 25 탆. The degree of swelling is measured with respect to 0.2 g of the adhesive film. The adhesive film was placed in a wire net (weight: A, unit: g, 200 mesh), and a wire net containing the adhesive film was placed in a 250 ml bottle. 100 ml of ethyl acetate was poured into the bottle to the extent that the wire net was immersed therein. , And the weight (B, unit: g) of the whole wire net containing the adhesive film after leaving the wire net containing the adhesive film at 25 DEG C for 30 minutes is calculated by the above formula (1).

(3) Creation of cracks: A pressure-sensitive adhesive sheet was prepared on a release film by coating the pressure-sensitive adhesive composition on a release film. The polyvinyl alcohol film was stretched three times at 60 DEG C, adsorbed iodine, and then stretched 2.5 times in an aqueous boric acid solution at 40 DEG C to prepare a polarizer. A triacetyl cellulose film was adhered to one surface of the polarizer and a polycarbonate film as a retardation film was adhered to the other surface of the polarizer. A polarizing plate was prepared by laminating an adhesive sheet on one side of a retardation film and aging at a constant aging time at constant temperature and humidity (35 캜, 45% relative humidity). The polarizing plate was cut into a width x length (25 mm x 50 mm), and a polarizing plate was attached to the slide glass at intervals of 1 mm. Heat treatment is performed at 200 ° C for 10 seconds, and after standing at room temperature for 10 seconds, isopropyl alcohol is applied to the end of the polarizing plate using a cotton swab. (24 hours at constant temperature and humidity of 60 ° C and 95% relative humidity) for 24 hours under heat-resistant condition (constant temperature of 85 ° C), or 24 hours at thermal shock condition (30 minutes at -40 ° C and 30 minutes at 85 ° C The film was observed under a microscope to see if cracks occurred in the retardation film.

○: No crack,

C: Crack having a length of 1 mm or less is present.

x: Cracks longer than 1 mm.

(4) Endurance reliability: A polarizing plate was produced in the same manner as in (3). The polarizing plate was cut into a width x length (100 mm x 125 mm), lapped with a liquid crystal cell, left under the heat, wet heat or thermal shock conditions as in (3), left at 25 DEG C for 1 hour, Bubble, peeling, or peeling.

○: No flaking, wrinkles, no bubbles.

?: Somewhat lifted and / or wrinkled

X: A lot of lifting and / or wrinkling.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

A polarizer, an optical film formed under the polarizer, and a pressure-sensitive adhesive film for a polarizer formed under the optical film,
Wherein the swelling degree of the formula (1) is 200% or less,
<Formula 1>
Swelling degree = (B - A) /0.2 x 100
(In the above formula 1, A represents the weight (unit: g) of the wire mesh (200 mesh) and B represents 0.2 g of the adhesive film. The wire mesh containing the adhesive film is placed in a 250 ml bottle, Ethyl acetate was added to allow the adhesive film contained in the wire net to be immersed and allowed to stand at 25 ° C for 3 days. The wire net containing the adhesive film was removed and left at 25 ° C for 30 minutes. Weight (unit: g)),
Wherein the adhesive film for a polarizing plate comprises a (meth) acrylic copolymer of a monomer mixture comprising 5 to 30% by weight of a (meth) acrylate having an unsubstituted alkyl group of C11 to C20,
Wherein the optical film is a film formed of at least one of an annular polyolefin resin, a polycarbonate resin, and an acrylic resin. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive film for polarizing plate is formed directly on the optical film. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive film for a polarizing plate has a storage modulus of 0.5 MPa to 10 MPa at 25 캜. The composition according to claim 1, wherein the (meth) acrylate having an unsubstituted alkyl group of C11 to C20 is selected from the group consisting of lauryl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, pentadecyl (Meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, nonadecyl (meth) acrylate. (Meth) acrylate having an unsubstituted alkyl group, a (meth) acrylate having a C1 to C10 unsubstituted alkyl group, a (meth) acrylate having a (Meth) acrylate and (meth) acrylic copolymer of a monomer mixture comprising a monomer having a carboxylic acid group. The pressure-sensitive adhesive film for a polarizing plate according to claim 1, wherein the pressure-sensitive adhesive film for a polarizing plate is formed of a pressure-sensitive adhesive composition comprising the (meth) acrylic copolymer and a curing agent, By weight, based on the total weight of the polarizer. The polarizing plate according to claim 6, wherein the curing agent comprises at least one of an isocyanate curing agent and a metal chelating curing agent. The polarizing plate according to claim 7, wherein the curing agent comprises a mixture of 9 to 20 parts by weight of an isocyanate curing agent and 0.1 to 5 parts by weight of a metal chelating curing agent. The polarizing plate according to claim 6, wherein the pressure-sensitive adhesive composition further comprises a silane coupling agent. The polarizing plate according to claim 1, wherein the optical film is a retardation film. The polarizer according to claim 1, wherein an optical film is further formed on the polarizer. An optical display device comprising the polarizing plate of any one of claims 1 to 11.

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