KR101780530B1 - Adhesive film for polarizing plate, adhesive composition for polarizing plate for the same, polarizing plate comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

The present invention relates to an adhesive film for a polarizing plate comprising an isocyanate group and formed from an adhesive composition comprising an epoxy compound, a (meth) acrylate compound and a compound having a reactive group and an isocyanate group, an adhesive composition for the polarizer, And an optical display device including the same.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive film for a polarizing plate, an adhesive composition for a polarizing plate for the same, and a polarizing plate including the same and an optical display device including the polarizing plate. SAME}

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

The polarizer includes an optical film formed on the upper surface and the lower surface of the polarizer and the polarizer, respectively, and the polarizer and the optical film can be adhered by an adhesive for the polarizer. A water-based adhesive is used as an adhesive for a polarizing plate. However, in a polarizing plate made of a water-based adhesive, the size of the polarizing plate changes due to the heat of the backlight unit, and distortion of the polarizing plate is caused in a part of the display screen due to a change in dimension thereof, have. Therefore, in the case where the optical film has a low moisture permeability, an adhesive for the photo-curable polarizing plate must be used because it is impossible to dry moisture for adhesion when using an aqueous adhesive, in particular, an adhesive for a photosetting type polarizing plate is used in place of the water- .

The cationic polymerizable photocurable adhesive for polarizing plate is subject to dark reaction (post polymerization) after irradiation with ultraviolet rays, so that curling may occur after the polarizing plate is produced, and it is likely to be influenced by humidity at the time of curing, thereby causing deviation before and after curing. On the other hand, the problem of the cationic polymerizable photocurable adhesive is relatively small in the adhesive for the radical photocurable polarizing plate, but the performance of the polarizing plate tends to be deteriorated when left in wet heat for a long time.

On the other hand, the polarizer of the polarizing plate is a film stretched in one direction, and moisture can be penetrated even after the stretching process or final manufacturing, and the polarizing plate can also be permeated with moisture from the outside, and the adhesive force, durability, Physical properties such as cohesive force may be lowered. In addition, the polarizing plate after the polarizing plate manufacturing process can be exposed in severe high humidity conditions during the transportation process, and an adhesive for a polarizing plate having reliability even when exposed to severe high humidity conditions is needed.

Korean Patent Laid-Open No. 2008-0093361 discloses a method for solving the thermal shock problem using an acrylate containing an N-substituted amide-based monomer.

An object of the present invention is to provide an adhesive film for a polarizing plate which can have both effects of an adhesive for a cationic polymerizable photocurable polarizing plate and an adhesive for a radical photocurable polarizing plate.

Another object of the present invention is to provide an adhesive film for a polarizing plate which does not cause generation of outgassing and does not deteriorate physical properties such as adhesion, durability and cohesive force even by moisture remaining in the polarizer and / or the optical film and / will be.

Another object of the present invention is to provide an adhesive film for a polarizing plate which is highly reliable when exposed to high humidity.

The adhesive film for a polarizing plate of the present invention may be formed of an adhesive composition for a polarizing plate containing an isocyanate group and containing an epoxy compound, a (meth) acrylate compound and a compound having a reactive group and an isocyanate group.

The adhesive composition for a polarizing plate of the present invention may comprise an epoxy compound, a (meth) acrylate compound, a compound having a reactive group and an isocyanate group, a photocationic polymerization initiator, and a photosensitizer.

The polarizing plate of the present invention may comprise an adhesive film for the polarizing plate.

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

The present invention provides an adhesive film for a polarizing plate that can have both the effects of an adhesive for a cationically polymerizable photocurable polarizing plate and an adhesive for a radical photocurable polarizing plate. The present invention provides an adhesive film for a polarizing plate that does not deteriorate physical properties such as adhesion, durability and cohesive force even by the moisture remaining in the polarizer and / or the protective film or the moisture permeating from the outside without generating outgas. The present invention provides an adhesive film for a polarizing plate which is highly reliable when exposed to high humidity.

1 is a sectional view of a polarizing plate of one embodiment of the present invention.
2 is a cross-sectional view of an optical display device according to an embodiment of the present invention.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. 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.

In the present specification, '(meth) acrylate' means acrylate and / or (meth) acrylate, and 'upper' and 'lower' , 'Lower' can be changed to 'upper', and '*' and '**' indicate the connecting part of the element.

Hereinafter, an adhesive film for a polarizing plate of one embodiment of the present invention will be described.

The adhesive film for a polarizing plate in one embodiment of the present invention is used for adhering an optical film to a polarizer, and the optical film may include a protective film, for example, a non-retardation film and / or a retardation film.

The adhesive film for a polarizing plate of one embodiment of the present invention may include an isocyanate group (* -N = C = O, * is a connecting site for an element). The isocyanate group is included in the free state of the polarizing plate adhesive film. When the moisture permeates into the adhesive film, the isocyanate group reacts with the water permeated to remove moisture, thereby reacting the isocyanate group with water to produce carbon dioxide. It is possible to prevent deterioration of physical properties such as durability and adhesive force of the adhesive film. Specifically, the isocyanate group in a glass state can be contained in an amount of 10% by weight or less, more preferably 0.05 to 1% by weight in the adhesive film, and the durability and adhesion of the adhesive film due to moisture can be prevented have. The 'glassy state' means a state in which an isocyanate group is not reacted (e.g., cross-linked) with a copolymer, various monomers, photosensitizer, initiator, additives, etc. constituting the adhesive film. When the isocyanate group is in the glass state, the adhesive film or moisture that can be permeated into the polarizing plate is removed, thereby improving the durability and adhesive force of the adhesive film.

Specifically, the isocyanate group may be included in the adhesive film as a "* -linker-isocyanate group ". The "linking group" varies depending on the compound having an isocyanate group in the adhesive composition, for example, it may be an unsubstituted alkylene group having 1 to 5 carbon atoms.

The adhesive film for a polarizing plate is made of an adhesive composition for a polarizing plate, and some of the isocyanate groups in the adhesive composition for a polarizing plate are copolymerized with a functional group (e.g., hydroxyl group) reactive with an isocyanate group and / or a monomer (e.g., Acrylate compound) or the like, the urethane bond may be contained in the adhesive film. However, the polarizing plate adhesive film of the present invention contains a relatively larger amount of isocyanate group in a free state as compared with the urethane-reacted isocyanate group, so that even after a long period of time after the production of the adhesive film or application of the adhesive film to the polarizing plate, .

The adhesive film of the present invention can be realized by the adhesive composition of the following embodiments of the present invention. Hereinafter, the adhesive composition for a polarizing plate of one embodiment of the present invention will be described.

The adhesive composition for a polarizing plate of the present invention comprises (A) an epoxy compound, (B) a (meth) acrylate compound, (C) a compound having a reactive group and an isocyanate group, (D) a photosensitizer, And an ionic polymerization initiator. As a result, the adhesive film for a polarizing plate of the present invention can prevent deterioration of adhesive force, durability and cohesive force due to moisture permeation by a compound having a reactive group and an isocyanate group.

(A) The epoxy compound imparts an adhesive force between the polarizer and the optical film, and can provide high reliability due to the structural strength of the epoxy itself. In addition, cohesive force can be imparted to the adhesive film by the following (meth) acrylate-based compound and physical molecular chain twist and chain transfer bonding with the hydrophilic group. In addition, the epoxy compound has a high glass transition temperature to support the structure of the adhesive film to impart durability, and it is possible to impart the interfacial adhesion between the polarizer and the optical film due to the chemical bond and good wettability caused by the hydroxyl group generated during the reaction . Specifically, the epoxy compound can have a glass transition temperature of from 50 to 250 캜, specifically from 100 to 200 캜. In this range, the durability can be enhanced and the interfacial adhesion between the polarizer and the optical film can be imparted.

(A) The epoxy-based compound may be a non-isocyanate-based epoxy-based compound having no isocyanate group. Specifically, (A) the epoxy compound may include an alicyclic epoxy compound, an aromatic epoxy compound, an aliphatic epoxy compound, and a hydrogenated epoxy compound, and these may be included singly or in combination of two or more.

The alicyclic epoxy compound may be a compound having at least one epoxy group in the alicyclic ring. The alicyclic epoxy-based compound may be an alicyclic diepoxycarboxylate. In particular embodiments, there may be mentioned 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro- (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexyl) adipate, 3,4-epoxy-6-methylcyclohexyl- 3 ', 4'-epoxy-6'-methylcyclohexanecarboxylate, ε-caprolactone modified 3,4-epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, trimethylcaprolactone denatured 3 , 4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone-modified 3,4-epoxycyclohexylmethyl-3'4, (3,4-epoxycyclohexanecarboxylate), ethylenebis (3,4-epoxycyclohexanecarboxylate), epoxycyclohexanecarboxylic acid esters such as ethylenebis Dioctyl phthalate, and the like epoxy cycloalkyl hexahydrophthalic acid di-2-ethylhexyl, and these may be contained alone or as a mixture of two or more.

The aromatic epoxy compounds include bisphenol A epoxy, bisphenol F epoxy, and phenol novolak epoxy, cresol novolak epoxy, bisphenol A-novolak epoxy, dichloropentadiene novolak epoxy, glycidyl ether of triphenolmethane, , Tetraglycidyl methylenedianiline, and the like, and they may be used alone or in combination of two or more.

The aliphatic epoxy compound may be 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether Diallyl ether, glycerin triglycidyl ether, polypropylene glycol diglycidyl ether; Polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin; Diglycidyl esters of aliphatic long chain dibasic acids; Monoglycidyl ethers of aliphatic higher alcohols; Glycidyl ethers of higher fatty acids; Epoxidized soybean oil; Butyl stearate; Octyl stearate; Epoxidized linseed oil; Epoxylated polybutadiene, and the like. These may be used alone or in combination of two or more.

The hydrogenated epoxy compound means a resin obtained by subjecting an aromatic epoxy resin to a hydrogenation reaction selectively under pressure in the presence of a catalyst. These resins may be used singly or in combination of two or more. Examples of the aromatic epoxy resin include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolak epoxy resin; Glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and epoxy polyvinylphenols, and the like. Although the hydrogenated epoxy resin of the aromatic epoxy resin becomes a hydrogenated epoxy resin, it is preferable to use hydrogenated bisphenol A glycidyl ether.

The epoxy compound (A) may be contained in an amount of 40 to 90 parts by weight based on 100 parts by weight of the total sum (A) + (B) + (C) of components (A), (B) and (C). In the above range, it is possible to prevent the polarizer from sticking to the optical film, to prevent the polarizer from being wetted due to an excessive increase in the viscosity of the adhesive composition, to prevent the adhesive layer from being broken due to excessive modulus rise, The crack resistance and the cuttability can be improved. Specifically 45 to 85 parts by weight based on 100 parts by weight of the total of (A), (B) and (C).

(A) the epoxy compound may be contained in an amount of 40 to 90% by weight based on the solid content of the adhesive composition. In the above range, the adhesive force between the polarizer and the optical film is good, the viscosity of the adhesive composition is excessively increased, the wettability of the polarizer can be prevented from being reduced, the adhesive layer can be prevented from being broken due to excessive modulus rise, It is possible to improve the anti-cracking property and the cuttability. Specifically, it may be contained in an amount of 45 to 80% by weight in the adhesive composition.

The (B) (meth) acrylate compound can undergo polymerization by a radical initiated by light energy. In addition, the polarizer can have high reactivity without being inhibited by the moisture of the polarizer, and can exhibit adhesion to each interface of the polarizer or optical film and chain transfer bonding with the activated epoxy compound during the curing process. The (B) (meth) acrylate-based compound is a non-isocyanate-based (meth) acrylate compound having no isocyanate group and rapidly cures to realize stable adhesion performance.

The (meth) acrylate compound (B) may be a monofunctional (meth) acrylate, a polyfunctional (meth) acrylate or a mixture thereof depending on the number of (meth) acrylate groups. The 'polyfunctional (meth) acrylate' may mean a compound having two or more, for example, two to six (meth) acrylate groups.

(B1) (meth) acrylate compounds may include (B1) a monofunctional (meth) acrylate having at least one hydroxyl group (hereinafter referred to as a (B1) (meth) acrylate compound) (Meth) acrylate compound can increase the interfacial adhesion between the polarizer and the optical film due to the hydroxyl group, and the bonding strength with the cationically activated epoxy compound.

(Meth) acrylate compound is a non-aromatic (meth) acrylate having no aromatic group and specifically includes an alkyl group having 1 to 10 carbon atoms having at least one hydroxyl group, preferably a carbon number having at least one hydroxyl group (Meth) acrylate having an alkyl group having 1 to 5 carbon atoms, (meth) acrylate having an alicyclic group having at least one hydroxyl group and having 3 to 10 carbon atoms. For example, a monofunctional (meth) acrylate having at least one hydroxyl group may be selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- (Meth) acrylate, 2-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (Meth) acrylate, 1,6-hexanediol mono (meth) acrylate, 4-hydroxycyclopentyl (meth) acrylate and 4-hydroxycyclohexyl May be one or more, and these may be included singly or in combination of two or more.

The (B1) (meth) acrylate compound may be contained in an amount of 10 to 60% by weight, specifically 15 to 55% by weight, more preferably 15 to 40% by weight in the adhesive composition. Can be.

(Meth) acrylate compounds (hereinafter referred to as (B2) (meth) acrylate compounds in which at least one epoxy group in the aromatic epoxy compound (B2) is substituted with a (meth) acrylate group ). ≪ / RTI > (A) an adhesive composition for a polarizing plate formed of only an epoxy compound and a (B1) (meth) acrylate compound may have a cohesive force after curing, and the cohesive force may be applied under ordinary humidity conditions (e.g., The cohesive force and / or the adhesive force can be maintained, but in a severe humidifying condition (for example, immersion of the adhesive film), the adhesive force is lowered and the optical film can be separated from the polarizer. On the other hand, the (B2) (meth) acrylate compound can significantly increase the curing degree of the (meth) acrylate based curing portion having a lower glass transition temperature than the epoxy compound (A), and as a result, An adhesive film can be formed.

(B2) (meth) acrylate compound is a compound in which all or part of the epoxy group in the aromatic epoxy compound is substituted with (meth) acrylate, in which a part of the epoxy group is substituted with a (meth) acrylate group, (Meth) acrylate group in the aromatic epoxy compound, and compounds having only a (meth) acrylate group without an epoxy group. Wherein the aromatic epoxy compound is selected from the group consisting of bisphenol A epoxy, bisphenol F epoxy, and phenol novolak epoxy, cresol novolak epoxy, bisphenol A-novolak epoxy, dichloropentadiene novolak epoxy, glycidyl ether of triphenolmethane, P-aminophenol, tetraglycidylmethylene dianiline, biphenyl epoxy, but are not limited thereto. Specifically, the (B2) (meth) acrylate-based compound may include at least one of bisphenol A epoxy di (meth) acrylate and biphenyl epoxy di (meth) acrylate.

The (B2) (meth) acrylate compound has at least one hydroxyl group, so that the interfacial adhesion between the polarizer and the optical film can be enhanced.

(B2) (meth) acrylate compound is used in an amount of from 0 to 10% by weight, for example, from 1 to 10% by weight, specifically from 1, 2, (B) from 0 to 30% by weight, such as from 1 to 30% by weight, particularly from 20 to 25% by weight, of the (meth) acrylate based compound, The effect is good and the interfacial adhesion with the protective film and / or the polarizer may not be reduced.

The (meth) acrylate compound (B) may further comprise (B3) a (meth) acrylate compound having no hydroxyl group (hereinafter referred to as (B3) (meth) acrylate compound). The (B3) (meth) acrylate compound is a non-hydroxylated machine having no hydroxyl group, which can improve the adhesion of an adhesive film to an optical film having hydrophobicity and can realize an adhesive film advantageous in severe humidity harsh conditions. The (B3) (meth) acrylate compound has one or more, for example, 1 to 5, for example 1, 2, 3, 4 or 5 aromatic groups to increase the curing rate, Can be adjusted.

Specifically, the (B3) (meth) acrylate compound is a non-epoxy system having no epoxy group and is an alkyl group having 1 to 10 carbon atoms substituted with an aryloxy group having 6 to 10 carbon atoms, specifically an aryloxy group having 6 to 10 carbon atoms (Meth) acrylate having a substituted alkyl group having 1 to 5 carbon atoms. For example, phenoxyethyl (meth) acrylate. The (B3) (meth) acrylate compound may be included in the adhesive composition in an amount of from 0 to 25% by weight, for example, from 9 to 25% by weight.

(B) (meth) acrylate compound may be contained in an amount of 5 to 50 parts by weight based on 100 parts by weight of the total of (A) + (B) + (C) of components (A), (B) and (C). In the above range, the adhesiveness is not lowered due to the lowering of the cohesive force, the tackiness due to the decrease of the interfacial adhesion and the modulus is not generated, the reliability is not lowered, and the polarizer is not discolored at the time of immersing the hot water. Specifically, 40 to 49.5 parts by weight of 100 parts by weight of (A) + (B) + (C) may be included.

The (B) (meth) acrylate-based compound may be contained in an amount of 15 to 50% by weight in the adhesive composition. In the above range, the adhesiveness is not lowered due to the lowering of the cohesive force, and the tackiness due to the decrease of the interfacial adhesion force and the modulus reduction does not occur, so that the reliability may not be deteriorated. Specifically, it may be contained in an amount of 16 to 49% by weight in the adhesive composition.

(C) In the compound having a reactive group and an isocyanate group, the reactive group can be a (meth) acrylate group, and as a result, it can react with the (B) (meth) acrylate compound to increase the durability of the adhesive film, There may be no. When a compound having an isocyanate group but no reactive group is included in the adhesive composition, it has a water-removing effect, but is not included in the (B) (meth) acrylate compound but is contained only as an additive in the adhesive film. This is because the film may cause clouding phenomenon.

Generally, a hybrid type polarizing plate adhesive composed of a cationic polymerizable curable epoxy and a radical curable (meth) acrylate system may deteriorate the adhesion at high humidity. (C) Some of the compounds having a reactive group and an isocyanate group react with the penetrated moisture to remove water, thereby preventing a decrease in adhesion due to moisture.

In addition, some of the compounds having (C) reactive groups and isocyanate groups are obtained by reacting (B1) a hydroxyl group and an isocyanate group of the (meth) acrylate compound with urethane reaction * -OH + ** - NCO → * -OCONH - It is possible to exhibit excellent durability against appearance changes such as crack prevention and cutting property by increasing the cohesive force and increasing the tensile strength. Therefore, the adhesive film for a polarizing plate of one embodiment of the present invention may also include a urethane bond, and as a result, the adhesive force, cohesion, durability and cuttability may be good.

In the compound (C) having a reactive group and an isocyanate group, one or more reactive groups may be included, for example, 1 to 3, and an isocyanate group may be included 1 to 3, for example, 1 to 3. For example, by including one reactive group and one isocyanate group, it is possible to reduce the possibility of the isocyanate group reacting with the hydroxyl group of the (B) (meth) acrylate compound to make a large number of isocyanate groups in a free state, It is possible to catch moisture penetrating into the body.

Specifically, the compound (C) having a reactive group and an isocyanate group may be represented by the following formula (1)

≪ Formula 1 >

CH ₂ ═CH (R ¹ ) -C (═O) O - R ² - NCO

(Wherein R ¹ is hydrogen or a methyl group, and R ² is an alkylene group having 1 to 5 carbon atoms).

For example, (C) the compound having a reactive group and an isocyanate group may be, but is not limited to, 2-isocyanatoethyl (meth) acrylate.

(C) a compound having a reactive group and an isocyanate group may increase in viscosity due to reaction with the (B1) (meth) acrylate compound in the adhesive composition as the content of the adhesive composition increases. When the viscosity increases, . In addition, the content of the (B1) (meth) acrylate compound is relatively decreased when the content of the (C) reactive group and the isocyanate group in the adhesive composition is increased. As the adhesive strength is increased, it may lower the adhesion to the polarizer. Therefore, (C) the compound having a reactive group and an isocyanate group may be contained in an amount of 10 parts by weight or less, for example, 0.05 to 10 parts by weight, based on 100 parts by weight of the total of the components (A), (B) and (C) 0.01 to 19 parts by weight, specifically 0.5 to 12 parts by weight, based on 100 parts by weight of the sum of the components (A) and (B), and the water resistance can be improved while maintaining the adhesive strength and cutability within the above range.

(D) The photosensitizer generates a small amount of radicals to catalyze the curing reaction. The adhesive composition for a polarizing plate of the present invention has a heterogeneous hybrid curing structure including both (A) an epoxy compound and (B) a (meth) acrylate compound, wherein the photosensitizer is (B) The reactivity of the photocationic polymerization initiator can be improved by not only curing the acrylate compound but also (A) catalyzing the initiation reaction of the photocationic polymerization initiator required for curing of the epoxy compound.

(D) the photosensitizer may include phosphorus, triazine, acetophenone, benzophenone, thioxanthone, benzoin, oxime or mixtures thereof. In embodiments, it may include a thioxantanone or a mixture thereof, a thioxanthene photosensitizer.

(D) the photosensitizer may be added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the total of (A), (B) and (C) The (meth) acrylate-based compound may be sufficiently cured under the light amount condition and the effect of improving the reactivity of the photocationic polymerization initiator may be obtained.

(E) the photocationic polymerization initiator may include a conventional photocationic initiator capable of carrying out a photocurable reaction. The photocationic polymerization initiator may include an onium salt of an onium ion and an onium salt of an anion. Specific examples of the onium ion include dia, such as diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, bis (4-tert- butylphenyl) iodonium, bis (dodecylphenyl) (Diphenylsulfonium) -phenyl] sulfide, bis [4- ((4-fluorophenylsulfonyl) phenyl] sulfide, triarylsulfonium such as thiodiphenylsulfonium, Phenyl] sulfide, 5-2,4- (cyclopentadienyl) [1,2,3,4,5,6-.eta.] Di (4- (2-hydroxyethyl) - (methylethyl) -benzene] -iron (1+). Specific examples of the anion include tetrafluoroborate (BF ₄ ^- ), hexafluorophosphate (PF ₆ ^- ), hexafluoroantimonate (SbF ₆ ^- ), hexafluoroarsenate (AsF ₆ ^- And chlorantimonate (SbCl ₆ ^- ).

(E) the photocationic polymerization initiator may be contained in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total of (A), (B) and (C). Within the above range, the polymerization of the epoxy compound can be sufficiently carried out and remaining amount of the initiator can be prevented from remaining.

The adhesive composition for a polarizing plate is prepared by mixing (A) an epoxy compound, (B) a (meth) acrylate compound, (C) a compound having a reactive group and an isocyanate group, (E) D) a photosensitizer, and mixing them.

The adhesive composition for a polarizing plate may have a viscosity of 30 to 80 cPs at 25 ° C, and the coating property and the coating property to the optical film may be good in the above range.

The adhesive composition for a polarizing plate may use a predetermined solvent, but it is preferable to use a solventless formulation to reduce the generation of outgas after curing. The adhesive composition for a polarizing plate may contain a conductivity-imparting additive such as an antioxidant, an ultraviolet absorber, an ion-type conductive agent, and a conductive metal oxide fine particle, a light diffusivity-imparting additive, a viscosity modifier, and the like within a range that does not impair the effect of the present invention have.

The adhesive film for a polarizing plate may be formed from the adhesive composition for a polarizing plate of the present invention. Specifically, the adhesive composition for a polarizing plate may be irradiated with light having a wavelength of 200-450 nm and a light intensity of 1-500 mW / cm 2 at an irradiation dose of 10-10,000 mJ / .

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

The thickness of the adhesive film for a polarizing plate may be 5 占 퐉 or less, preferably 1 占 퐉 to 5 占 퐉. In the above range, it can be used as an adhesive film for a polarizing plate.

The adhesive film for a polarizing plate may have a glass transition temperature of 55 to 105 ° C, specifically 75 to 105 ° C, and the effect of suppressing deformation under the reliability condition may be obtained in the above range.

The polarizing plate of the present invention may include an adhesive film formed of an adhesive composition for a polarizing plate of one embodiment of the present invention. Hereinafter, a polarizing plate of one embodiment of the present invention will be described with reference to FIG. 1 is a sectional view of a polarizing plate of one embodiment of the present invention.

1, the polarizing plate 100 of the embodiment of the present invention includes a polarizer 110, a first polarizing plate adhesive film 120 formed on the upper surface of the polarizer 110, a first polarizing plate adhesive film 120 A second polarizing plate adhesive film 140 formed on the lower surface of the polarizer 110 and a second optical film 140 formed on the lower surface of the second polarizing plate adhesive film 140, And one of the first adhesive film for polarizing plate 120 and the second adhesive film for polarizing plate 140 may be formed of an adhesive composition for a polarizing plate according to one embodiment of the present invention.

The polarizer 110 can be produced by dying and stretching iodine onto a film made of a polyvinyl alcohol-based resin. As the polyvinyl alcohol-based resin, polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, or a saponified product of an ethylene-vinyl acetate copolymer can be used. The saponification degree of the polyvinyl alcohol-based resin film may be 99 or more, preferably 99 to 99.5, and the degree of polymerization may be 2000 or more, preferably 2000 to 2500, and the thickness may be 10 to 200 占 퐉. The thickness of the polarizer may be 10 탆 to 200 탆, and the polarizer may be used in the above range.

The first optical film 130 and the second optical film 150 may be at least one of a protective film and a retardation film, but is not particularly limited as long as it is a transparent film. As a specific example, the protective film may be a non-retardation film such as a cellulose-based film including triacetyl cellulose (TAC), a polyester-based film including polyethylene terephthalate (PET), a cyclic polyolefin (COP )- based film, a polycarbonate , Polyacrylate type, polyether sulfone type, polysulfone type, polyamide type, polyimide type, polyolefin type, polyarylate type, polyvinyl alcohol type, polyvinyl chloride type, polyvinylidene chloride type or mixtures thereof A film made of a material selected from the group consisting of The retardation film can be used without restriction as long as the retardation film is a film having a? / 2 or? / 4 retardation function. For example, a film made of an olefinic, acrylic, cellulose, or a mixture thereof including a cycloolefin polymer (COP) can be used.

The first optical film 130 and the second optical film 150 may each have a thickness of 25 탆 to 500 탆. In the above range, it can be used as a polarizing plate when laminated on a polarizing element. And preferably 25 占 퐉 to 100 占 퐉.

The first optical film 130 and the second optical film 150 may have different thicknesses and / or materials. FIG. 1 shows a case where the first optical film 130 and the second optical film 150 have different thicknesses and / or materials. However, the same thickness and materials may be included in the scope of the present invention.

The first optical film 130 and the second optical film 150 may be subjected to a surface treatment, for example, a corona pre-treatment step of 250 mJ / cm ² or more before the application of the adhesive composition or before the preparation of the polarizing plate.

The first polarizing plate adhesive film 120 may be formed of an adhesive composition for a polarizing plate according to an embodiment of the present invention and the second polarizing plate adhesive film 140 may be formed of a conventional polarizing plate adhesive composition such as an aqueous adhesive or a curing adhesive . FIG. 1 shows a case where the adhesive film for a first polarizing plate 120 and the adhesive film for a second polarizing plate 140 are formed of different adhesive compositions for a polarizing plate, but both the adhesive film for a first polarizing plate and the adhesive film for a second polarizing plate But also the case where it is formed of the adhesive composition for a polarizing plate of the present invention can be included in the scope of the present invention.

The polarizing plate can be produced by a conventional method. For example, an adhesive composition for a polarizing plate is applied to one side of a protective film to produce a protective film having an adhesive composition layer. Drying and the like can be carried out if necessary. As the coating method, for example, a die coating method, a roll coating method, a gravure coating method and a spin coating method can be used. A protective film having the above-mentioned adhesive composition layer is laminated on each of the upper and lower surfaces of the polarizer to obtain a laminate. The adhesive layer is formed by curing the adhesive composition layer by irradiating ultraviolet rays, from which the polarizing plate can be produced. Ultraviolet irradiation can be performed by irradiating light having a wavelength of 200-450 nm and an illumination of 1-500 mW / cm ² at an irradiation dose of 10-10,000 mJ / cm ² .

The optical display device of the present invention may include the polarizer adhesive composition, the adhesive film formed of the adhesive composition, or a polarizer including the same. The optical display device is a conventional optical display device including a polarizing plate, and may include, for example, a liquid crystal display or the like. 2 is a cross-sectional view of an optical display device according to an embodiment of the present invention.

2, an optical display device 200 according to an embodiment of the present invention includes a liquid crystal panel 210, a first polarizer 220 formed on the liquid crystal panel 210, and a second polarizer 220 formed below the liquid crystal panel 220. [ And a polarizer 230. At least one of the first polarizer 220 and the second polarizer 230 may be a polarizer of the present invention.

Hereinafter, the present invention will be described in more detail by way of 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) Epoxy system: Aliphatic cycloepoxy (SEE-4221, Seechem)

(B1) 4-Hydroxybutyl acrylate (100%, Osaka Organic (JAPAN)), (B2) Bisphenol A Epoxy diacrylate (PE210, Miwon), (B3) Phenoxyethyl acrylate (M140, Miwon )

(C) a compound having a reactive group and an isocyanate group: 2-Isocyanatoethyl acrylate (KarenzAOI ™, Karenz)

(D) Photosensitizer: Diethylthioxanthone (DETX-S, Nipponkayaku)

(E) Gwangyang Ion Polymerization Initiator: hexaflourophosphate Iodonium salt (Irgacure-250, BASF)

Examples 1 to 7 and Comparative Examples 1 to 3

(A) an epoxy compound, (B) a (meth) acrylic compound, and (C) a compound having a reactive group and an isocyanate group in the amounts shown in Table 1 (unit: parts by weight). Then, 1 part by weight of the photosensitizer (D) and 3 parts by weight of the cationic polymerization initiator (E) were mixed and mixed to prepare an adhesive composition for a polarizing plate.

Production of Polarizer

A polyvinyl alcohol film (degree of saponification: 99.5, degree of polymerization: 2000) having a thickness of 80 탆 was immersed in a 0.3% iodine aqueous solution and salt-baked, followed by drawing to a draw ratio of 5.0. Subsequently, the stretched polyvinyl alcohol film was immersed in a boric acid solution of 3% concentration and an aqueous solution of 2% potassium iodide to perform color correction, and then dried at 50 DEG C for 4 minutes to prepare a polarizer (thickness 25 mu m).

Triacetate cellulose 80㎛ thickness of the upper protective film (TAC) film, a 80㎛ thick polyethylene terephthalate (PET) film, the thickness 80㎛ acrylic (ACRYL) was used for the film, each of at least 250 mJ / cm ² corona treated Respectively. A cycloolefin-based (COP) resin film having a thickness of 30 탆 was used as a lower protective film, and corona treatment was performed at 250 W.min / m ² or more.

Under the environment of temperature of 22 to 25 캜 and humidity of 20 to 60%, the upper protective film was laminated in the order of the adhesive composition of the examples and comparative examples, the polarizer and the examples, and the adhesive composition of the comparative example and the lower protective film, And irradiated with ultraviolet rays under a condition of 400 mW / cm ² and 1000 mJ / cm ² with a metal halide lamp to prepare a polarizing plate (thickness 140 μm) .

(A) (B) (C) Top protective film Lower protective film (B1) (B2) (B3) Example 1 50 32 8 - 10 TAC COP Example 2 50 36 9 - 5 TAC COP Example 3 50 39.2 9.8 - One TAC COP Example 4 50 39.6 9.9 - 0.5 TAC COP Example 5 50 39.2 9.8 - One PET COP Example 6 50 39.2 9.8 - One ACRYL COP Example 7 50 20 10 10 10 TAC COP Comparative Example 1 50 40 10 - - TAC COP Comparative Example 2 50 - - - 50 TAC COP Comparative Example 3 - 70 10 10 10 TAC COP

The following properties of the adhesive composition or polarizing plate for a polarizing plate of Examples and Comparative Examples were evaluated and shown in Table 2.

Whether or not an isocyanate group is included in the adhesive film Viscosity (cPs) Cutting Adhesiveness Hot water appearance Room temperature immersion separation Example 1 ○ 72 ○ ○ ◎ ○ Example 2 ○ 65 ◎ ○ ◎ ◎ Example 3 ○ 56 ◎ ◎ ◎ ◎ Example 4 ○ 55 ◎ ◎ ◎ ◎ Example 5 ○ 53 ◎ ◎ ◎ ◎ Example 6 ○ 51 ◎ ◎ ◎ ◎ Example 7 ○ 60 ○ ○ ◎ ○ Comparative Example 1 × 51 ◎ ◎ × × Comparative Example 2 ○ 8 × × ◎ × Comparative Example 3 ○ 40 × ○ ○ ×

As shown in Table 2, the adhesive film for a polarizing plate of the present invention does not deteriorate physical properties such as adhesion, durability and cohesive force even by moisture remaining in the polarizer and / or the protective film including water and penetrating from the outside, The reliability was high. In addition, it was confirmed that both the cationic polymerizable photocurable polarizing plate adhesive and the radical photocurable polarizing plate adhesive can have both effects.

On the other hand, Comparative Example 1, which did not contain a reactive group and a compound having an isocyanate group, had a problem of water resistance, Comparative Example 2 which did not include a (meth) acrylate compound had a problem of interfacial adhesion, Comparative Example 3, which was not used, had a problem of cuttability due to weak cohesive force and flocculation separation at room temperature.

(1) Viscosity: The adhesive composition for a polarizing plate was measured with a PP25 measurement instrument at an angular velocity of 1000 / s using a rheometer (Physica, MCR-501) at 25 ° C.

(2) Cutting property: The polarizing plate was subjected to press cutting at a size of 5 x 5 cm (width x height), and it was confirmed whether or not the polarizing plate was peeled off between the films. The peeled state of the cut portion from the four sides of the polarizing plate was visually observed. A peeling of not more than 1 mm and not more than 2 mm was evaluated as?, And a peeling of not less than 2 mm was evaluated as x.

(3) Adhesiveness: In order to confirm the adhesiveness of the polarizing plate adhesive film, a cutter cutter was inserted between the protective film at the end of the polarizing plate and the polarizer. The point where the edge of the sword did not enter between the protective film and the polarizer was evaluated as?, The edge of the sword was inserted a little,? The edge of the sword was slightly inserted, but the protective film was torn during the constant strength.

(4) Hot water appearance: A sample is made so that the polarizing plate is 5 cm x 5 cm in width and length. And immersed in constant temperature water (60 DEG C) for 2 hours, respectively. The highest values of the decolorization of the polarizer and the contraction length of the one end of the polarizer were measured. The shrinkage length means the minimum value of the distance from the end of the protective film to the end of the polarizer adjacent to the polarizer after the hot water immersion test. The protective film does not shrink in the water resistance test, but the polarizer shrinks when immersed in hot water. A polarizer was peeled and discolored.?, A polarizer was peeled off from 1 mm or less to 1 mm or less.?, A polarizer was peeled off from 2 mm or less and 2 mm or less was peeled off.

(5) Immersion at room temperature: The polarizing plate was immersed in glass at 25 ° C for 24 hours, and then evaluated in the same manner as in the adhesion evaluation.

Claims (14)

Isocyanate group,
Is an adhesive film for a polarizing plate which is formed from an adhesive composition comprising an epoxy compound, a (meth) acrylate compound and a compound having a reactive group and an isocyanate group,
The isocyanate group is contained in a free state in the polarizing plate adhesive film,
The compound having a reactive group and an isocyanate group is represented by the following general formula (1)
≪ Formula 1 >
CH ₂ ═CH (R ¹ ) -C (═O) O - R ² - NCO
(Wherein R ¹ is hydrogen or a methyl group and R ² is an alkylene group having 1 to 5 carbon atoms)
The reactive group and the compound having an isocyanate group are contained in an amount of 0.01 to 19 parts by weight based on 100 parts by weight of the total amount of the epoxy compound and the (meth) acrylate compound,
The (meth) acrylate-based compound includes a compound in which at least one of the monofunctional (meth) acrylate and aromatic epoxy compound having at least one hydroxyl group is substituted with (meth) acrylate, and the aromatic epoxy A compound in which at least one epoxy group in the compound is substituted with (meth) acrylate has at least one hydroxyl group,
Wherein the isocyanate group in the free state in the adhesive film for a polarizing plate is contained in an amount of 0.05 to 10% by weight. delete The adhesive film for a polarizing plate according to claim 1, wherein the adhesive film comprises a urethane bond. delete delete The adhesive film for a polarizing plate according to claim 1, wherein the (meth) acrylate-based compound further comprises a (meth) acrylate-based compound having no hydroxyl group. The composition according to claim 1, wherein the compound in which at least one epoxy group of the aromatic epoxy compound is substituted with (meth) acrylate is at least one of bisphenol A epoxy di (meth) acrylate and biphenyl epoxide (meth) Wherein the polarizing plate is a polarizing plate. The adhesive film for a polarizing plate according to claim 1, wherein the epoxy compound is an alicyclic epoxy compound, an aromatic epoxy compound, an aliphatic epoxy compound, a hydrogenated epoxy compound, or a mixture thereof. The adhesive film for a polarizing plate according to claim 1, wherein the adhesive composition further comprises a photocationic polymerization initiator and a photosensitizer. (A) an epoxy compound, (B) a (meth) acrylate compound, (C) a compound having a reactive group and an isocyanate group, (D) a photocationic polymerization initiator, and (E) a photosensitizer ,
The compound (C) having a reactive group and an isocyanate group is represented by the following general formula (1)
≪ Formula 1 >
CH ₂ ═CH (R ¹ ) -C (═O) O - R ² - NCO
(Wherein R ¹ is hydrogen or a methyl group and R ² is an alkylene group having 1 to 5 carbon atoms)
The adhesive film for a polarizing plate formed of the adhesive composition for a polarizing plate contains an isocyanate group in a free state,
The compound (C) having a reactive group and an isocyanate group is contained in an amount of 0.01 to 19 parts by weight based on 100 parts by weight of the total amount of the epoxy compound (A) and the (B) (meth) acrylate compound,
The (B) (meth) acrylate-based compound includes a compound in which at least one of the monofunctional (meth) acrylate and aromatic epoxy compound having at least one hydroxyl group is substituted with (meth) The compound in which at least one epoxy group in the aromatic epoxy compound is substituted with (meth) acrylate has at least one hydroxyl group,
Wherein the isocyanate group in the free state in the adhesive film for a polarizing plate is contained in an amount of 0.05 to 10% by weight. delete The adhesive composition for a polarizing plate according to claim 10, wherein the compound (C) having a reactive group and an isocyanate group is contained in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the total of the components (A), (B) and (C). An adhesive film for a polarizing plate according to any one of claims 1, 3, 6, 7, 8, and 9, or an adhesive film for a polarizer formed of the adhesive composition for a polarizing plate of claim 10 or 12, Containing polarizer. An optical display device comprising the polarizing plate of claim 13.

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