WO2016017922A1 - Adhesive for polarizing plate, polarizing plate comprising same and optical display device comprising same - Google Patents

Abstract

Embodiments of the present invention can provide: an adhesive for a polarizing plate, of which the fusibility index represented by formula 1 is approximately 1.3 to about 4.0 with respect to a polycarbonate film; a polarizing plate comprising the same; and an optical display device comprising the same.

Description

Adhesive for polarizing plate, polarizing plate comprising same and optical display device comprising same

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

The liquid crystal display includes a liquid crystal panel and a polarizer to display a screen, and the liquid crystal panel may be divided into TN (twisted nematic), VA (vertical alignment), and IPS (in-plane switch) according to the liquid crystal driving method. have. Among them, the liquid crystal display device adopting the IPS method should include a polarizing plate including a protective film having zero phase difference. Currently, protective films having zero retardation include triacetyl cellulose (TAC) films and cycloolefin-based (COP) films. However, since the TAC film has a high moisture transmittance, the polarizer may be unreliable when the polarizer is left in a harsh condition of high temperature and / or high humidity, and the COP film may be difficult to process when used in a protective film or a polarizer. Thus, polycarbonate (PC) film or the like is used to replace the TAC, COP film. PC film is more water-resistant and flexible, making it easier to perform than TAC and COP films.

By the way, a PC film is a poorly adhesive film which is inferior to the conventional water-based polyvinyl alcohol-type adhesive agent, or the photocurable adhesive agent containing an epoxy and / or (meth) acrylate. Therefore, the PC film may be peeled off from the polarizer due to low peeling force on the polarizer, or may be deteriorated in durability and reliability under severe conditions such as heat resistance, moisture resistance, and thermal shock after being applied to the polarizer.

Background of the present invention is disclosed in Korean Patent Laid-Open No. 2012-0095227.

An object of the present invention is to provide an adhesive for polarizing plates having excellent adhesion to a polycarbonate film which is a poorly adhesive film.

Another object of the present invention is to provide an adhesive for a polarizing plate that is durable and reliable under severe conditions such as heat resistance, moisture resistance, and thermal shock when a polycarbonate film is adhered to a poor adhesive film.

Still another object of the present invention is to provide an adhesive for a polarizing plate having excellent adhesion to a polycarbonate film but not affecting the physical properties of the polarizer even when used to bond the polycarbonate film and the polarizer.

It is still another object of the present invention to provide a polarizing plate having excellent adhesion between a polycarbonate film and a polarizer and having excellent durability and reliability under severe conditions such as heat resistance, moisture resistance, and thermal shock.

The adhesive for polarizing plates of the present invention may have a solubility index of about 1.3 to about 4.0 represented by Formula 1 for the polycarbonate film:

<Equation 1>

Solubility Index = V2 / V1

In Formula 1, V1, V2 are as defined in the detailed description of the invention below.

The polarizing plate of the present invention may include the adhesive for polarizing plate.

Polarizing plate of the present invention is a polarizer; And a polarizing plate adhesive layer formed on one or both surfaces of the polarizer. And a polycarbonate film formed on the adhesive layer for the polarizing plate, and the adhesive layer for the polarizing plate may be formed of the adhesive for the polarizing plate.

The optical display device of the present invention may include the polarizing plate.

The present invention provides an adhesive for a polarizing plate having excellent adhesion to a polycarbonate film that is a poor adhesive film. The present invention provides a durable, reliable polarizing plate adhesive in the harsh conditions such as heat resistance, moisture resistance, thermal shock when bonding a polycarbonate film that is a poor adhesive film. The present invention provides an adhesive for a polarizing plate that does not affect the polarizer even when used to bond the polycarbonate film and the polarizer. The present invention provides a polarizing plate having excellent adhesion between a polycarbonate film and a polarizer and having excellent durability and reliability under severe conditions such as heat resistance, moisture resistance, and thermal shock.

1 is a cross-sectional view of a polarizing plate of an embodiment of the present invention.

2 is a cross-sectional view of an optical display device according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In the present specification, the 'top' and 'bottom' are defined based on the drawings, and according to the viewpoint, 'top' may be changed to 'bottom' and 'bottom' may be changed to 'top'.

As used herein, '(meth) acrylate' means acrylate and / or methacrylate.

In the present specification, the 'solubility index' for the polycarbonate film with respect to the adhesive is measured using a rheometer (Physica MCR-501, Anton Parr), in which the polycarbonate film (thickness: 20 μm) mounted on the bottom plate is used. The adhesive for polarizing plate (uncured state in liquid phase) was applied to a thickness of 100 μm, adhered to the upper plate, and the initial viscosity value of the adhesive for polarizing plate measured at 25 ° C. and 50% relative humidity was V1 (unit: cPs), The viscosity of the adhesive for polarizing plates measured at 25 ° C. and 50% RH after 10 minutes of rotation at 25 ° C. and 50% RH at normal shear rate 1000 (sec ⁻¹ ) is called V2 (unit: cPs). When the mean value is calculated by the following formula 1:

<Equation 1>

Solubility Index = V2 / V1

In the present specification, the 'soluble index' for the non-soluble component and the soluble component constituting the adhesive for the polarizing plate has a non-soluble component and a soluble component contained in the adhesive for the polarizing plate instead of the adhesive for the polarizing plate, respectively, in Formula 1 for the polarizing plate Means the value calculated by measuring in the same manner as the measurement of the solubility index of the adhesive.

Hereinafter, the adhesive for polarizing plates of one embodiment of the present invention will be described.

The adhesive for polarizing plates of one embodiment of the present invention has a solubility index of about 1.3 to about 4.0 for the polycarbonate film. When the solubility index is less than about 1.3, the adhesive strength between the polarizer and the polycarbonate film is low, thereby lowering the reliability of the polarizing plate. In addition, the surface of the polycarbonate film may be destroyed by the adhesive when the solubility index exceeds 4.0. In this case, the polycarbonate film and the polarizer may be well adhered as the polycarbonate film is partially dissolved by the wetting of the polycarbonate film to the adhesive when the adhesive is in contact with the polycarbonate film. Therefore, there is no separation phenomenon between the polycarbonate film and the polarizer, and the polycarbonate film may be used as a protective film of the polarizer without the breakage of the surface of the polycarbonate film and the non-uniformity of the adhesive force due to excessive dissolution of the polycarbonate film by the adhesive.

Specifically, the solubility index for the polycarbonate film of the polarizing plate adhesive may be about 1.5 to about 3.8. Within this range, the adhesion between the polarizer and the polycarbonate film is more excellent and the reliability of the polarizing plate can be improved even under the harsh conditions of high temperature and / or high humidity.

In addition, when the sample prepared by adhering the polycarbonate film and the polarizer using the adhesive for the polarizing plate was fixed to both sides of a universal testing machine (UTM) (TA XT Plus, Texture Technologies, Inc.) and peeled at a peel rate of 300 mm / min. The peel force measured can be from about 90 gf / 25 mm to about 170 gf / 25 mm.

The polycarbonate film may be a conventional modified polycarbonate film. For example, for a polarizing plate used in a liquid crystal display device employing an in-plane switch (IPS) liquid crystal mode, a low phase difference, for example, in-plane phase difference (Ro) of about 0 nm to about 1,000 nm, specifically about 0 nm to about It can be a polycarbonate film having 50nm. For example, the polycarbonate film may be an aromatic polycarbonate film containing a heterocycloaliphatic group, for example, a heterocycloaliphatic group having 3 to 10 carbon atoms containing oxygen, nitrogen, or sulfur.

In one embodiment, the polycarbonate film is a polycarbonate resin having a unit of formula (1), a polycarbonate resin having a unit of formula (2), a film of at least one of the polycarbonate resin having a unit of the formula (1) and 2 Can include:

<Formula 1>

<Formula 2>

In Formulas 1 and 2, * is a linking site of an element, A is -CH ₂ -Y-CH _2- , wherein Y is represented by a cycloalkylene group having 4 to 20 carbon atoms or the following formula (3).

<Formula 3>

In Formula 3, * is a linking site for -CH ₂ -in A of Formula 2, R ₁ , R ₂ , R ₃ , R ₄ are the same or different, each independently hydrogen or an alkyl group having 1 to 5 carbon atoms to be.

In one embodiment, the polycarbonate resin may be prepared by reacting a carbonate ester forming compound with a dihydroxy compound represented by Formula 4 and Formula 5 below:

<Formula 4>

<Formula 5>

In Formula 5, Y is represented by a cycloalkylene group having 4 to 20 carbon atoms or represented by the following Formula 6.

<Formula 6>

In Formula 6, * is a linking site for —CH ₂ — in Formula 5, and R ₁ , R ₂ , R ₃ , and R ₄ are the same or different, and are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms.

The dihydroxy compound of formula 4 may be isosorbide (isosorbide), isomannide (isomannide), these may be used alone or two or more kinds. The dihydroxy compound of formula 5 is tricyclodecane dimethanol, pentacyclopentadedecimethanol, 2,6-decalindimethanol, 1,4-cyclohexanedimethanol, norbornane dimethanol, cyclopentane-1,3- Dimethanol, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane and the like, and these may be used alone or in combination of two or more. Can be used. The carbonate ester forming compound is a carbonate compound commonly used in the production of a polycarbonate resin, and for example, diphenyl carbonate may be used.

The number of moles of Formula 1 in the polycarbonate resin: The number of moles of Formula 2 is about 99: 1 to about 1:99, specifically about 90:10 to about 10, based on the sum of the number of moles of Formula 1 and the number of moles of Formula 2 Can be: 90 The polycarbonate resin may have a glass transition temperature of about 90 ° C. to about 200 ° C., for example, about 100 ° C. to about 190 ° C., in the above range, having good heat resistance and moldability, and improving the surface hardness of the protective film. There can be. Polycarbonate resin may have a weight average molecular weight of about 30,000 g / mol to about 200,000 g / mol, specifically about 40,000 g / mol to about 150,000 g / mol, in the above range, the strength of the protective film May be good, and moldability may be good.

The polycarbonate resin may further include structural units derived from aromatic dihydroxy compounds in addition to Chemical Formulas 4 and 5. The aromatic dihydroxy compound is a compound commonly included in the production of an aromatic polycarbonate resin, for example, may be bisphenol A, but is not limited.

The polycarbonate film has a photoelastic coefficient of about 10 x 10 ^-12 Pa ^-1 to about 70 x 10 ^-12 Pa ^-1 , for example about 60 x 10 ^-12 Pa ^-1 to about 70 x 10 ^-12 Pa ^-1 The surface hardness may be about 2B or less, for example about 6B to about 7B.

The polycarbonate film may be an unstretched type polycarbonate film that does not stretch the film made of polycarbonate resin.

In addition, the polycarbonate film may be the polycarbonate film disclosed in JP 5448264, JP 5033935 or JP 4938151 and the like. Polycarbonate resins are commercially available, and polycarbonate resins may be purchased from Mitsubishi Chemical Co., Ltd. (Durabio, modified polycarbonate resins), etc., and melted and coextruded to produce a film (thickness: 10 μm to 50 μm).

In order to realize the solubility index, the adhesive for polarizing plate of the embodiment of the present invention may include a non-soluble component having a solubility index of about 1.5 or less, a solubility component having a solubility index of more than about 1.5, and an initiator for a polycarbonate film. It may include. Adhesives each comprising a non-insoluble component and a soluble component alone are difficult to adjust the solubility index of the adhesive to about 1.3 to about 4.0, and there may be a problem of lowering the overall adhesive strength due to lack of cohesion within the adhesive or lack of interfacial adhesion of the polycarbonate film. have.

The insoluble component is to prevent the polycarbonate film from being excessively dissolved by the soluble component and to destroy the surface of the film and to secure adhesion. The solubility index is about 1.5 or less, specifically about 0.5 to about 1.5, more specifically about 0.9 to about It may be 1.1, in the above range to secure the adhesive force to the polycarbonate film, copolymerizing with the soluble component to have a stable curing structure to have an effect of improving the internal cohesion of the adhesive.

The insoluble component is a monofunctional photocurable monomer having a photocurable functional group of at least one of an epoxy group, a (meth) acrylate group, a polyfunctional photocurable monomer, or a mixture thereof, the molecular weight being from about 50 g / mol to about 500 g / mol. And solubility index of about 1.5 or less can be secured in the above range.

Specifically, the insoluble component is an alicyclic epoxy compound, an aromatic epoxy compound, an alkyl group-containing (meth) acrylate having 1 to 10 carbon atoms having at least one hydroxyl group, aliphatic glycidyl ether, phenoxyethyl (meth) acryl It may include one or more of the rates. The alicyclic means an alicyclic group having 3 to 10 carbon atoms, the aromatic means an aromatic group having 6 to 20 carbon atoms, and the aliphatic means an alkyl group having 1 to 20 carbon atoms. More specifically, the non-soluble component is alicyclic epoxy (trade name: CY179, Celloxide 2021P), bisphenol A epoxy, bisphenol F epoxy (trade name: KDS-8170), phenol novolak epoxy, cresol novolac epoxy, bisphenol Aromatic epoxy compound containing A novolak epoxy system, etc., phenoxyethyl acrylate (brand name: M140), 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, alapathic ( aliphatic) may comprise one or more of glycidyl ether (trade name: EX212L), which has a better mixing effect with the soluble component. The insoluble component may be included alone or in mixture of two or more kinds of the adhesive for polarizing plates.

The soluble component is included in the adhesive for the polarizing plate to physically dissolve some of the interface of the polycarbonate film to provide adhesion to the poorly adhesive polycarbonate film, so that the solubility index may be greater than about 1.5, for example, about 1.55 to about 10.5. In the above range, the interface breakage phenomenon due to excessive dissolution does not occur, and there may be an effect of securing adhesion to the polycarbonate film.

The soluble component is a monofunctional or polyfunctional photocurable monomer comprising at least one photocurable functional group of an epoxy group or a (meth) acrylate group, and may have a molecular weight of about 50 g / mol to about 500 g / mol, in the above range A solubility index greater than about 1.5 can be obtained.

Specifically, the soluble component includes (meth) acrylate having a heteroalicyclic group, mono- or diglycidyl ether having an aromatic group, (meth) acrylate having a glycidyl group, and (meth) acrylate having an ethylene oxide group. It may include one or more of. The 'heteroalicyclic group' means an alicyclic group having 2 to 5 carbon atoms containing oxygen, nitrogen, sulfur, preferably means a tetrahydrofuran group, the 'aromatic group' is a substituted or unsubstituted carbon 6 to 20 means an aryl group, where 'substituted' in 'substituted or unsubstituted' means that at least one hydrogen is substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and the like. A phenyl group, a resorcinol group, and a t-butylphenyl group are meant. For example, the soluble component may be tetrahydroperfuryl (meth) acrylate, phenylglycidyl ether, resorcinol diglycidyl ether, (t-butyl) phenyl glycidyl ether, glycidyl (meth) acrylate. And ethoxyethoxyethyl (meth) acrylate. The soluble component may be included alone or in mixture of two or more kinds of adhesives for polarizing plates.

The solubility index of the adhesive for polarizing plates is mainly controlled by the content of the insoluble component and the soluble component. In order to secure the solubility index of about 1.3 to about 4.0 of the adhesive, the insoluble component of the total of 100 parts by weight of the insoluble component and the soluble component is From about 35 parts by weight to about 75 parts by weight, the soluble component may be included from about 25 parts by weight to about 65 parts by weight, the appropriate adhesion to the polycarbonate film in the above range can be obtained and the interfacial stability of the polycarbonate film can be ensured. For example, about 100 parts by weight of the insoluble component and the soluble component may include about 35 parts by weight to about 70 parts by weight, and the soluble component may include about 30 parts by weight to about 65 parts by weight.

The initiator is used to cure the insoluble component and / or the soluble component to form an adhesive layer, and may include one or more of a photocationic polymerization initiator and a photosensitizer.

The photocationic polymerization initiator generates a cation by light irradiation to cure it, and may include a conventional photocationic polymerization initiator capable of carrying out a photocurable reaction. The photocationic polymerization initiator may include an onium salt of a cation and an anion. As a specific example of a cation, diphenyl iodonium, 4-methoxy diphenyl iodonium, bis (4-methylphenyl) iodonium, (4-methylphenyl) [(4- (2-methylpropyl) phenyl], bis (4-tert- Triarylsulfonium, bis [4- (, such as diaryl iodonium, triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, such as butylphenyl) iodonium and bis (dodecylphenyl) iodonium; Diphenylsulfonio) -phenyl] sulfide, bis [4- (di (4- (2-hydroxyethyl) phenyl) sulfonio) -phenyl] sulfide, etc. As a specific example of an anion, borate (BF ₄ ^-) tetrafluoroborate, hexafluorophosphate (PF ₆ ^-), antimonate hexafluorophosphate (SbF ₆ ^-), are Senate hexafluorophosphate (AsF ₆ ^-), hexachloro antimonate ( sbCl ₆ ^-) and the like.

The photosensitizer generates a small amount of radicals by light irradiation to catalyze the curing reaction. The photosensitizers are phosphorus, triazine, acetophenone, benzophenone, thioxanthone, benzoin, oxime or these It may include a mixture of. In embodiments, by using a thioxanthone-based photosensitizer may be further improved reactivity.

The initiator may be included in an amount of about 0.1 part by weight to about 10 parts by weight, specifically about 1 part by weight to about 6 parts by weight, based on 100 parts by weight of the total solid-based insoluble component and the soluble component in the adhesive for the polarizing plate, and cured in the above range. Is sufficiently advanced and the residual amount of initiator remains to prevent the permeability of the adhesive layer from decreasing.

The adhesive for polarizing plates can be manufactured by mix | blending an insoluble component and a soluble component, adding an initiator, and mixing. The adhesive for polarizing plates may have a viscosity of about 30 mPa · s to about 120 mPa · s at 25 ° C., and may have good coating property and coating property on the polycarbonate film in the above range.

Although the adhesive for polarizing plates may be a solventless type which does not contain a solvent, coating property and coating property can be improved by further including the organic solvent, such as a solvent, for example, methyl ethyl ketone.

The adhesive for polarizing plate further contains additives, such as an antioxidant, a ultraviolet absorber, an ionic conductive agent, electroconductivity additives, such as electroconductive metal oxide microparticles | fine-particles, a light-diffusion imparting additive, and a viscosity modifier, in the range which does not impair the effect of this invention. can do.

The adhesive film for a polarizing plate of an embodiment of the present invention is coated with an adhesive for a polarizing plate of the embodiment of the present invention, such as a base film, the irradiation amount of light with a wavelength of about 200 nm to about 450 nm, roughness of about 1 mW / cm ² to about 500 mW / cm ² irradiation at about 10mJ / cm ² to about 10,000mJ / cm ^2, and may be prepared by removing from the substrate film.

The adhesive film for the polarizing plate may have a haze of about 0% to about 20%, for example, about 0.2% to about 4.5% at a thickness of about 0.1 μm to about 10 μm and a wavelength of about 400 nm to about 700 nm. In the above range, even if adhered to a polarizer or an optical film, the optical transmittance may not be a problem.

The thickness of the adhesive film for the polarizing plate may be about 3 μm or less, for example, about 1 μm to about 3 μm. In the said range, it can be used as an adhesive film for polarizing plates.

The polarizing plate adhesive film may have a glass transition temperature of about 55 ° C. to about 105 ° C., specifically about 70 ° C. to about 100 ° C., and may have good adhesion, durability, and adhesion after immersion in the above range. .

The polarizing plate of the embodiment of the present invention may include a polarizing plate adhesive film formed of the polarizing plate adhesive of the embodiment of the present invention and / or the adhesive for the polarizing plate of the embodiment of the present invention. Specifically, the polarizing plate of the embodiment of the present invention includes a polarizer, a polarizing plate adhesive film formed on at least one surface of the polarizer, and a polycarbonate film formed on one surface of the adhesive film for polarizing plates, the adhesive film for the polarizing plate adhesive of the polarizing plate of the embodiment of the present invention It may include an adhesive film for a polarizing plate formed as.

The polarizing plate of the present invention may include an adhesive layer formed of the adhesive for polarizing plate of the present invention or the adhesive for polarizing plate of the present invention. Specifically, the polarizing plate of the present invention; And a polarizing plate adhesive layer formed on one or both surfaces of the polarizer. And a polycarbonate film formed on the adhesive layer for the polarizing plate, and the adhesive layer for the polarizing plate may be formed of the adhesive for the polarizing plate of the present invention. As a result, the polarizing plate of the present invention has excellent adhesion between the polycarbonate film and the polarizer without the influence of physical properties on the polarizer even if the polarizing plate including a hard-adhesive polycarbonate film, because of this, in the harsh conditions such as heat resistance, moisture resistance, thermal shock, Reliability can be good. The polycarbonate film may include the conventional modified polycarbonate film described above.

Hereinafter, a polarizer of an embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of a polarizing plate of an embodiment of the present invention.

Referring to FIG. 1, the polarizing plate 100 according to the exemplary embodiment of the present invention is formed on the polarizer 110, the adhesive film 120 for the first polarizing plate formed on the polarizer 110, and the adhesive film 120 for the first polarizing plate 120. A first optical film 130, a second polarizing plate adhesive film 140 formed under the polarizer 110, and a second optical film 150 formed under the second polarizing plate adhesive film 140; The first polarizing plate adhesive film 120 is formed of the polarizing plate adhesive of the embodiment of the present invention, the first optical film 130 may include a polycarbonate film.

The polarizer 110 polarizes natural light or artificial light and may be made of a polyvinyl alcohol-based film. For example, the polarizer is produced by dyeing iodine or dichroic dye on a modified polyvinyl alcohol film such as a partially formalized polyvinyl alcohol film, an acetoacetyl group-modified polyvinyl alcohol film, and stretching it in a predetermined direction. Specifically, it is prepared through the swelling process, the dyeing step, the stretching step. Methods of performing each step are commonly known to those skilled in the art.

The polarizer 110 may have a thickness of about 10 μm to about 50 μm, and may be used for the optical display device in the above range.

The first optical film 130 may be the polycarbonate film described above. In particular, when the first optical film 130 is a polycarbonate film having an in-plane phase difference (Ro) of about 0 nm to about 50 nm at a wavelength of 550 nm, the first optical film 130 may be placed on the liquid crystal display panel side when the polarizing plate is attached to the liquid crystal display panel. It may be more desirable for viewing angle and IPS mode when sticking.

The second optical film 150 may be an optically transparent film. For example, the second optical film 150 is a non-polycarbonate-based film, specifically, a cellulose-based containing triacetyl cellulose (TAC), a polyester-based containing polyethylene terephthalate (PET), and a cyclic polyolefin. (COP) type, polyacrylate type, polyether sulfone type, polysulfone type, polyamide type, polyimide type, acyclic polyolefin type, polyacrylate type, polyvinyl alcohol type, polyvinyl chloride type, polyvinyl chloride type It may be one or more films of the lidene system.

However, not only the first optical film 130 but also the polarizing plate in which the second optical film 150 is the aforementioned polycarbonate film may be included in the scope of the present invention.

The thicknesses of the first optical film 130 and the second optical film 150 may be the same or different, and may each have a thickness of about 25 μm to about 500 μm, for example, about 25 μm to about 100 μm, In the above range, it can be used for the polarizing plate.

The first polarizing plate adhesive film 120 may be formed of the polarizing plate adhesive of the embodiment of the present invention, the second polarizing plate adhesive film 140 is a polarizing plate adhesive (for example, the solubility index deviates from 1.3 to 4.0 of the polarizing plate) Solvent adhesive, specifically an aqueous adhesive). However, the polarizing plate formed of the adhesive film for the second polarizing plate 140 of the polarizing plate of the embodiment of the present invention may also be included in the scope of the present invention.

Although not shown in FIG. 1, an adhesive film may be further formed on an upper surface of the first optical film 130 or a lower surface of the second optical film 150 to attach the polarizer to the liquid crystal display panel.

In addition, although not shown in FIG. 1, a functional coating layer may be further formed on an upper surface of the first optical film 130 or a lower surface of the second optical film 150 to provide additional functions to the polarizing plate. It may be a hard coating layer, an anti-fingerprint layer, an antireflection layer, or the like.

A polarizing plate can be manufactured by a conventional method. For example, the adhesive composition for polarizing plates is apply | coated to one side of a protective film, and the protective film which has an adhesive composition layer is manufactured. Drying etc. can be performed as needed. As the coating method, for example, a die coating method, a roll coating method, a gravure coating method, or a spin coating method can be used. A protective film having the adhesive composition layer is laminated on each of the upper and lower surfaces of the polarizer to obtain a laminate. An adhesive layer is formed by irradiating an ultraviolet-ray and hardening an adhesive composition layer, from which a polarizing plate can be manufactured. UV irradiation may be performed by irradiation of about 200-450nm, light intensity of about 1 mW / cm ² to about 500mW / a light dose of about 10 mJ / cm ² to about ² cm of 10,000mJ / cm ² wavelength. The first optical film and the second optical film may be subjected to a surface treatment, for example, at least about 250 mJ / cm ² corona pretreatment step before application of the adhesive composition or before the manufacture of the polarizing plate.

The optical display device of the embodiment of the present invention may include the polarizing plate of the embodiment of the present invention. The optical display device is a conventional optical display device including a polarizing plate, and may include, for example, a liquid crystal display. 2, an optical display device 200 according to an exemplary embodiment of the present invention includes a liquid crystal panel 210, a first polarizing plate 220 formed on one surface of the liquid crystal panel 210, and another surface of the liquid crystal panel 210. A second polarizing plate 230 is formed between the light source unit 240, the first polarizing plate 220 may include a polarizing plate of the embodiment of the present invention.

The second polarizing plate 230 may include a conventional polarizing plate (eg, a polarizing plate not including the adhesive film for the polarizing plate of the present invention), but the optical display device in which the second polarizing plate is the polarizing plate of the embodiment of the present invention is also within the scope of the present invention. Can be included.

The liquid crystal panel 210 may adopt a twisted nematic (TN), a vertical alignment (VA), an in-plane switch (IPS), or the like, and may employ, for example, an IPS liquid crystal mode.

The light source unit 240 may include a backlight unit.

Although not shown in FIG. 2, an adhesive film (not shown in FIG. 2) may be formed between the liquid crystal panel 210 and the first polarizing plate 220 and between the liquid crystal panel 210 and the second polarizing plate 230. , The pressure-sensitive adhesive film may be formed of a pressure-sensitive adhesive (PSA, pressure sensitive adhesive) or the like for a conventional polarizing plate.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Specific specifications of the components used in the following Examples and Comparative Examples are as follows.

A) Insoluble Ingredients:

A1) CY179 (cycloaliphatic epoxy, Huntsman, Solubility Index: 0.99)

A2) KDS-8170 (bisphenol F epoxy, Kukdo Chemical, Solubility Index: 1.02)

A3) HEA: 2-hydroxyethyl acrylate (soluble index: 1.01),

A4) EX212L (aliphatic glycidyl ether, Nagase chemtex, solubility index: 1.05),

A5) M140 (phenoxy ethyl acrylate, Miwon, Solubility Index: 1.06)

B) Soluble Ingredients:

B1) THFA (tetrahydroperfuryl acrylate, Eternal Chemical, Solubility Index: 2.14),

B2) EX141 (phenylglycidyl ether, Nagase Chemtex, Solubility Index: 1.83),

B3) GMA (glycidyl methacrylate, Sigma Aldrich, Solubility Index: 10.11),

B4) M170 (ethoxyethoxyethyl acrylate, Miwon, Solubility Index: 1.88)

C) Initiator: Iodonium salt (Irgacure-250, Basf) of hexaflourophosphate

Example  1 to 7 lessons Comparative example  1 to 3

The insoluble component and the soluble component without the solvent were combined in the content of Table 1 (unit: parts by weight). An initiator was blended in the amount (unit: parts by weight) of Table 1 to prepare an adhesive for a polarizing plate.

Comparative example  4

A water-based adhesive was prepared by mixing 3.5 parts by weight of polyvinyl alcohol resin, 1 part by weight of polyethyleneimine, and 0.1 part by weight of zirconium compound (zirconium oxide) to 100 parts by weight of water.

Preparation of Polarizer

An 80 micrometer-thick polyvinyl alcohol film (blackness: 99.5, polymerization degree: 2000) was immersed in a 0.3% aqueous solution of iodine for dyeing, and stretched so that the draw ratio was 5.0. Subsequently, the stretched polyvinyl alcohol film was immersed in a boric acid solution and a 2% potassium iodide solution at a concentration of 3% for color correction, and dried at 50 ° C. for 4 minutes to prepare a polarizer (thickness 25 μm).

A 100 μm thick polyethylene terephthalate (PET) film was used as the upper protective film, and a primer layer including urethane was formed on the surface of the PET film in order to secure adhesive strength. As a lower protective film, a polycarbonate film (Mitsubishi Chemical Co., Ltd., Durabio® T7450 resin melt coextrusion), a non-stretch type film, was used, and the film surface was corona-treated at 100 W.min / m ² .

Upper protective film-Polarizer adhesive-Polarizer-Polarizer adhesive-Lower protective film in the order of 22 ℃ to 25 ℃, humidity 20% to 60% environment, 300mW / cm with a metal halide lamp ² , 1000 mJ / cm ² conditions to irradiate the ultraviolet light, the polarizing plate (thickness 160㎛) In this case, the polarizing plate adhesives of Examples and Comparative Examples were used as adhesives for the polarizing plate.

	Insoluble ingredients					Soluble Ingredients				Initiator	Solubility Index of Adhesives
	CY179	KDS-8170	HEA	EX212L	M140	THFA	EX141	GMA	M170
Example 1	50	-	-	-	-	30	20	-	-	5	1.5
Example 2	60	-	-	-	-	-	20	20	-	5	2.9
Example 3	-	50	-	-	-	30	-	20	-	5	3.2
Example 4	-	50	-	-	-	-	30	-	20	5	3.5
Example 5	5	55	10	-	-	-	20	10	-	5	2.1
Example 6	-	35	-	5	-	35	-	25	-	5	3.7
Example 7	30	-	-	-	5	30	30	-	5	5	1.6
Comparative Example 1	80	-	-	-	-	-	20	-	-	5	1.2
Comparative Example 2	30	-	-	-	-	-	30	40	-	5	4.9
Comparative Example 3	100	-	-	-	-	-	-	-	-	5	1.0
Comparative Example 4	-	-	-	-	-	-	-	-	-	-	-

The physical properties of the adhesives for the polarizing plates and the polarizing plates prepared therefrom in Examples and Comparative Examples were evaluated and shown in Table 2.

	Peeling state
	Breaking mode	Peeling force (gf / 25㎜)
Example 1	Cohesive failure of adhesive	134
Example 2	Cohesive failure of adhesive	150
Example 3	Cohesive failure of adhesive	129
Example 4	Cohesive failure of adhesive	106
Example 5	Cohesive failure of adhesive	96
Example 6	Cohesive failure of adhesive	93
Example 7	Cohesive failure of adhesive	101
Comparative Example 1	PC film interface separation	25
Comparative Example 2	PC Film Surface Destruction / Coagulation	58
Comparative Example 3	PC film interface separation	15
Comparative Example 4	PC film interface separation	5

As shown in Table 2, the adhesive for a polarizing plate of the present invention has a solubility index of about 1.3 to about 4.0 for the polycarbonate film, so that both the adhesive remains on both the polycarbonate film and the polarizer even after peeling off the polycarbonate film and the polarizer. The adhesion (peel strength) between the polycarbonate film and the adhesive was good. Accordingly, the polarizing plate including the adhesive layer formed of the adhesive for polarizing plate of the present invention has good adhesion between the polycarbonate film and the polarizer, and thus, may be excellent in durability and reliability under severe conditions such as heat resistance, moisture resistance, and thermal shock.

On the other hand, in Comparative Example 1 having a solubility index of less than 1.3, when the polycarbonate film and the polarizer were peeled off, the adhesive did not remain on both the polarizer and the polycarbonate film, so that the adhesive force (peelability) between the polycarbonate film and the adhesive was not good, and the solubility index was low. Comparative Example 2 exceeding 4.0 was confirmed that the interface of the polycarbonate film is not dissolved to implement the performance of the polycarbonate film, the adhesion between the polarizer and the polycarbonate film is also lower than the present invention.

Comparative Example 3 containing a non-insoluble component alone had a problem of polycarbonate interface peeling, Comparative Example 4 adhered to the existing water-based adhesive had a problem of polycarbonate interface peeling. Therefore, the polarizing plate of the comparative example which does not contain the adhesive agent for polarizing plates of this invention may not have the adhesive force between a polycarbonate film and a polarizer, and / or may be poor in durability and reliability.

<Property evaluation method>

1) Adhesive solubility index: Rheometer (Physica MCR-501, Anton Parr) equipped with a polycarbonate film (thickness: 20 μm, a film melt-coextruded from Mitsubishi Chemical's Durabio® T7450 resin) on a lower plate with a diameter of 25 mm G) is prepared, and the adhesive for polarizing plates is apply | coated so that it may become 100 micrometers thick, and it contacts with the upper plate of diameter 25mm. The initial viscosity value of the adhesive measured at 25 ° C. and 50% relative humidity is called V1 (cps). Viscosity of the adhesive measured at 25 ° C and 50% RH after 25 minutes at 25 ° C and 50% RH at a normal shear rate of 1000 (sec ^-1 ) at 25 ° C and 50% relative humidity is called V2 (unit: cps). The solubility index of the adhesive is V2 / V1.

2) Solubility index of insoluble components and soluble components, which are adhesive components: Measure in the same manner as 1), but using insoluble components and soluble components instead of adhesives.

3) Peeling state: Insert the cutter tip between the polycarbonate film and the polarizer of the polarizer and slightly peel off, then fix the polarizer and the polycarbonate film on both sides of the universal testing machine (UTM) (TA XT Plus, Texture Technologies) and 300mm / When peeling at the peeling rate of min, the peeling force was measured. When the polarizer and the polycarbonate film are peeled off, when the adhesive is present on both the polarizer and the polycarbonate film, and the adhesive bonds the polarizer and the polycarbonate film, the cohesive failure of the adhesive is not present and the adhesive is not present on the surface of the polarizer and the polycarbonate film. Therefore, when the adhesive fails to bond the polarizer and the polycarbonate film, it is described as 'PC film interface separation', and when the polycarbonate film is dissolved and the surface of the polycarbonate film is broken, it is described as 'PC film surface destruction / aggregation failure'.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (15)

1. Adhesive for polarizing plates having a solubility index of about 1.3 to about 4.0 represented by Formula 1 for the polycarbonate film:

   <Equation 1>

   Solubility Index = V2 / V1

   In Equation 1, V1 is the initial viscosity (cPs) of the adhesive for the polarizing plate measured at 25 ℃ and 50% relative humidity for the specimen coated with the adhesive for the polarizing plate to the polycarbonate film having a thickness of 20㎛ 100㎛ ego,

   V2 is the viscosity (cPs) of the adhesive for polarizing plates measured at 25 ° C. and 50% RH after 10 minutes rotation of the specimen at a shear rate of 1000 sec ⁻¹ at 25 ° C. and 50% RH.
2. The adhesive for polarizing plates of Claim 1 whose said polycarbonate film is an aromatic polycarbonate film containing a heteroalicyclic group.
3. According to claim 1, wherein the polycarbonate film is a polycarbonate resin having a unit of formula (1), a polycarbonate resin having a unit of formula (2), polycarbonate resin having a unit of the formula (1) and 2 Adhesive for polarizing plates, comprising a film:

   <Formula 1>

   

   <Formula 2>

   

   In Chemical Formulas 1 and 2, * is a linking site of an element, A is -CH ₂ -Y-CH _2- , wherein Y is a cycloalkylene group having 4 to 20 carbon atoms or represented by the following Chemical Formula 3

   <Formula 3>

   

   In Formula 3, * is a linking site for -CH ₂ -in A of Formula 2, R ₁ , R ₂ , R ₃ , R 4 are the same or different, each independently hydrogen or an alkyl group having 1 to 5 carbon atoms .
4. The adhesive of claim 1 wherein the adhesive for polarizing plate comprises a non-soluble component having a solubility index of about 1.5 or less for the polycarbonate film, a soluble component having a solubility index of more than about 1.5 for the polycarbonate film, and an initiator. Adhesive for polarizing plate.
5. The polarizing plate of claim 4, wherein the non-soluble component has a solubility index of about 0.5 to about 1.5 for the polycarbonate film, and the soluble component has a solubility index of about 1.55 to about 10.5 for the polycarbonate film. Glue.
6. The method of claim 4, wherein the non-insoluble component is an alicyclic epoxy compound, an aromatic epoxy compound, an alkyl group containing (meth) acrylate having 1 to 10 carbon atoms having at least one hydroxyl group, aliphatic glycidyl ether, phenoxyethyl Adhesive for polarizing plates containing one or more of (meth) acrylates.
7. The soluble component according to claim 4, wherein the soluble component has a (meth) acrylate having a heteroalicyclic group, a mono- or diglycidyl ether having an aromatic group, a (meth) acrylate having a glycidyl group, and an ethylene oxide group ( Adhesives for polarizing plates containing one or more of meth) acrylates.
8. The method according to claim 4, wherein the non-soluble component comprises about 35 parts by weight to about 75 parts by weight and the soluble component contains about 25 parts by weight to about 65 parts by weight based on 100 parts by weight of the non-insoluble component and the soluble ingredient. Phosphorus, adhesive for polarizing plates.
9. 5. The adhesive for polarizing plate according to claim 4, wherein the initiator comprises at least one of a photocationic polymerization initiator and a photosensitizer.
10. The polarizing plate containing the adhesive agent for polarizing plates of Claim 1.
11. Polarizer; And

    An adhesive layer for polarizing plates formed on one or both surfaces of the polarizer; And

    It comprises a polycarbonate film formed on the adhesive layer for the polarizing plate,

    The said adhesive layer for polarizing plates is a polarizing plate formed from the adhesive agent for polarizing plates of Claim 1.
12. The polarizing plate of claim 11, wherein the polycarbonate film has an in-plane retardation (Ro) of about 0 nm to about 1,000 nm at a wavelength of 550 nm.
13. The polarizing plate according to claim 11, wherein the polycarbonate film is an aromatic polycarbonate film containing a heteroalicyclic group.
14. The method of claim 11, wherein the polycarbonate film is made of at least one of a polycarbonate resin having a unit of formula 1, a polycarbonate resin having a unit of formula 2, a polycarbonate resin having a unit of formula 1 and 2 Polarizing plate comprising a film:

    <Formula 1>

    

    <Formula 2>

    

    In Chemical Formulas 1 and 2, * is a linking site of an element, A is -CH ₂ -Y-CH _2- , wherein Y is a cycloalkylene group having 4 to 20 carbon atoms or represented by the following Chemical Formula 3

    <Formula 3>

    

    In Formula 3, * is a linking site to -CH ₂ -in A of Formula 2, R ₁ , R ₂ , R ₃ , R ₄ are the same or different, each independently hydrogen or an alkyl group having 1 to 5 carbon atoms to be.
15. An optical display device comprising the polarizing plate of claim 10.

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