KR20150087329A - Adhesive composition for optical films, adhesive optical film, and laminate - Google Patents

Abstract

A pressure-sensitive adhesive composition for an optical film, a pressure-sensitive adhesive optical film, and a pressure-sensitive adhesive film which can realize high adhesive force and excellent durability when used for adhering an adherend such as a liquid crystal cell and an optical film such as a polarizing film, Provide sieve.
A pressure-sensitive adhesive composition for an optical film is provided which contains an acrylic polymer (A) having a crosslinkable functional group and a crosslinking agent (B), having a maximum strain of 10% or less and a strain recovery rate of 50% or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition for an optical film, a pressure-sensitive adhesive optical film for an optical film,

The present invention relates to a pressure-sensitive adhesive composition for an optical film, a pressure-sensitive adhesive optical film, and a laminate.

BACKGROUND ART [0002] Image display devices have been used in recent years under a variety of uses and conditions. For example, they are used not only under room temperature conditions, but also under extreme conditions such as high temperature and high temperature and humidity. Examples of the use in a high temperature or high temperature and high humidity condition include use in a tropical region, use in a vehicle or in an outdoor measurement device.

An optical film such as a polarizing film constituting an image display apparatus is produced by adsorbing a dye having dichroism to a polymer film such as polyvinyl alcohol, and stretching and orienting the dye. For this reason, the optical film shrinks under high temperature or high humidity environment, and dimensional distortion is likely to occur. It is difficult to completely return to the original dimensions even if the optical film is deformed once, even if it is changed to a temperature condition or a humidity condition. As a result, cracks, peeling, and lifting occur in the pressure-sensitive adhesive layer due to the influence of the stress caused by the dimensional change of the optical film, or light leakage due to deformation of the polarization axis occurs in the image display device.

In addition, recent image display apparatuses are required to have a large screen, high image quality, and high durability. For example, when the image display device is a liquid crystal display device, a method of using an LED for a light source is widely adopted in order to meet the demand for power saving. In the case of a liquid crystal display device in which an LED is used as a light source, there is a remarkable demand for high image quality and high durability against heat and light from a light source. However, in the case of a liquid crystal display device employing a method of using an LED for a light source, the light leakage tends to be prominent because the brightness of the LED as the light source is high.

Japanese Patent Application Laid-Open No. 2007-169329

The present invention relates to a pressure-sensitive adhesive composition for an optical film that exhibits excellent durability under high-temperature and high-humidity conditions and can reduce light leakage when used for adhering an adherend such as a liquid crystal cell and an optical film such as a polarizing film, An adhesive optical film using the same, and a laminate.

In order to solve such a problem, the present inventors have found that when a pressure-sensitive adhesive layer is formed by using a pressure-sensitive adhesive composition having a predetermined viscoelastic property and is used for adhering an adherend such as a liquid crystal cell and an optical film such as a polarizing film, I found that I could reduce it.

1. The pressure-sensitive adhesive composition for an optical film according to one embodiment of the present invention comprises an acrylic polymer (A) having a crosslinkable functional group and a crosslinking agent (B), wherein the maximum strain defined below is not more than 10% Is at least 50%.

Maximum strain: A pressure-sensitive adhesive sheet having a thickness of 1 mm obtained by applying the pressure-sensitive adhesive composition for an optical film on a flat plate and drying the pressure-sensitive adhesive sheet was cut into 8 mm, and the following test pieces 1 to 3 were measured (%) At the time when the strain becomes maximum,

Final strain: Strain (%) of the test piece after the following measuring steps 1 to 3 were carried out in sequence using a rheometer.

Deformation recovery rate: A value obtained by applying a pressure-sensitive adhesive sheet for optical film to a test piece obtained by applying a pressure-sensitive adhesive composition for an optical film on a flat plate and drying the pressure-sensitive adhesive sheet cut to a thickness of 8 mm,

Strain recovery rate (%) = (maximum strain - final strain) / maximum strain x 100 ... (One)

Measuring Step 1: While increasing the temperature of the sample piece from 23 DEG C to 80 DEG C for 15 minutes at a constant rate, the shearing stress of the sample piece is increased from 0 Pa to 1000 Pa for 15 minutes at a constant rate

Measuring Step 2: While maintaining the temperature of the sample piece at 80 占 폚 for 30 minutes, the shear stress is increased from 1000 Pa to 2000 Pa at a constant rate for 30 minutes

Measuring Step 3: While the temperature of the sample piece is reduced from 80 ° C to 23 ° C at a constant rate for 15 minutes, the shearing stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes

2. The pressure-sensitive adhesive composition for an optical film according to 1 above, wherein the acrylic polymer (A) having a crosslinkable functional group does not have a crosslinkable functional group and the (meth) acrylate ester having a glass transition temperature (Tg) (meth) acrylic ester (a2) having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 占 폚 and 44.5 to 94.5 mass% of a monomer having a crosslinkable functional group (a1) (a3) 0.5 to 6 mass%, wherein the total amount of (a1), (a2) and (a3) in the monomer mixture is 90 to 100 mass%.

3. The pressure-sensitive adhesive composition for an optical film according to 1 or 2, wherein the (meth) acrylate ester (a1) is a (meth) acrylic acid alkyl ester, and the alkyl chain constituting the alkyl ester portion of the (meth) (Wherein the number of carbon atoms in the alkyl chain is from 1 to 20) may be a linear or branched alkyl chain.

(4) The pressure-sensitive adhesive composition for an optical film according to any one of (1) to (3), wherein the acrylic polymer (A) having a crosslinkable functional group has a Tg of -70 to 0 캜.

5. The pressure-sensitive adhesive composition for an optical film according to any one of 1 to 4, wherein the acrylic polymer (A) having a crosslinkable functional group has a weight average molecular weight of 500,000 to 200.

6. The pressure-sensitive adhesive composition for an optical film according to any one of 1 to 5, wherein the gel fraction is 70% or more.

7. A pressure-sensitive adhesive composition for optical films according to another embodiment of the present invention comprises an acrylic polymer (A) having a crosslinkable functional group and a crosslinking agent (B)

The acrylic polymer (A) having a crosslinkable functional group,

(Meth) acrylic acid ester (a1) having no crosslinkable functional group and having a glass transition temperature (Tg) of 0 占 폚 or more,

44.5 to 94.5 mass% of a (meth) acrylic acid ester (a2) having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 占 폚,

Wherein the total amount of the monomer mixture (a1), (a2) and (a3) in the monomer mixture is from 90 to 100 mass% %), And the gel fraction may be 70% or more.

8. A pressure-sensitive adhesive optical film according to another aspect of the present invention, wherein a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition for an optical film according to any one of 1 to 7 above is formed on one side or both sides of the optical film.

9. The adhesive optical film according to 8 above may be an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness improving film and a light diffusion film.

10. A laminate according to another aspect of the present invention comprises a glass substrate, a polarizing plate, and a pressure-sensitive adhesive composition for an optical film as described in any one of 1 to 7, which is formed between the glass substrate and the polarizing plate, And a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive composition for an optical film has a suitable adhesive strength and exhibits excellent durability under high temperature or high temperature and high humidity conditions. When used for adhering an optical film such as a polarizing film to an adherend such as a liquid crystal cell, Can be reduced. The adhesive optical film using the pressure-sensitive adhesive composition for an optical film is adhered (adhered) to an adherend such as a liquid crystal cell with an appropriate adhesive force, exhibits excellent durability under high temperature or high temperature and high humidity conditions, When used for adhesion to an adherend such as a cell, light leakage can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph schematically illustrating the time-course change of the strain of a pressure-sensitive adhesive composition for an optical film according to an embodiment of the present invention measured using a rheometer.
2 is a diagram schematically illustrating a method of measuring the luminance of an image display apparatus (liquid crystal display panel) in an embodiment of the present invention.
3 is a view for explaining a method of measuring a strain using a rheometer for a test piece of the pressure-sensitive adhesive composition of the present invention.
4 is a cross-sectional view schematically showing an example of a laminate including a pressure-sensitive adhesive layer obtained by using a pressure-sensitive adhesive composition for an optical film according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, " part " means " mass part ", and "% " means " mass% "

1. Pressure-sensitive adhesive composition for optical film

The pressure-sensitive adhesive composition for an optical film according to one embodiment of the present invention (hereinafter sometimes simply referred to as "pressure-sensitive adhesive composition") comprises an acrylic polymer (A) having a crosslinkable functional group , And a cross-linking agent (B) (hereinafter sometimes simply referred to as " component (B) ").

The pressure-sensitive adhesive composition for an optical film according to the present embodiment has a maximum strain of 10% or less as defined below, and a strain recovery rate as defined below of 50% or more.

Maximum strain: A pressure-sensitive adhesive sheet having a thickness of 1 mm obtained by applying the pressure-sensitive adhesive composition for an optical film on a flat plate and drying the pressure-sensitive adhesive sheet was cut into 8 mm, and the following test pieces 1 to 3 were measured (%) At the time when the strain becomes maximum,

Final strain: Strain (%) of the test piece after the following measuring steps 1 to 3 were carried out in sequence using a rheometer.

Deformation restoration ratio: A test piece obtained by applying a pressure-sensitive adhesive composition for an optical film according to the present invention on a flat plate and drying the pressure-sensitive adhesive sheet obtained by cutting the pressure-sensitive adhesive sheet of 1 mm in thickness into 8 mm, value

Strain recovery rate (%) = (maximum strain - final strain) / maximum strain x 100 ... (One)

Measuring Step 1: While increasing the temperature of the sample piece from 23 DEG C to 80 DEG C for 15 minutes at a constant rate, the shearing stress of the sample piece is increased from 0 Pa to 1000 Pa for 15 minutes at a constant rate

Measuring Step 2: While maintaining the temperature of the sample piece at 80 占 폚 for 30 minutes, the shear stress is increased from 1000 Pa to 2000 Pa at a constant rate for 30 minutes

Measuring Step 3: The shearing stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes while the temperature of the sample piece is decreased from 80 캜 to 23 캜 at a constant rate for 15 minutes.

1.1. Maximum strain and strain recovery

The " maximum strain " in the present invention is an index of ease of deformation of the pressure-sensitive adhesive composition, and it can be said that the pressure-sensitive adhesive composition tends to be deformed as the maximum strain is large. In the pressure-sensitive adhesive composition for an optical film according to the present embodiment, when the maximum strain exceeds 10%, the pressure-sensitive adhesive layer can not follow the expansion or contraction of the adherend of the pressure-sensitive adhesive, resulting in birefringence in the pressure- Can not be prevented. In the pressure-sensitive adhesive composition for an optical film according to the present embodiment, the maximum strain is preferably 10% or less, more preferably 8% or less, in view of more reliably preventing birefringence generated in the pressure- Is more preferable.

In the present invention, the " strain recovery ratio " is an index of ease of recovery of the modified pressure-sensitive adhesive composition. It can be said that the larger the strain recovery ratio is, the more easily the pressure- In the pressure-sensitive adhesive composition for an optical film according to the present embodiment, if the deformation recovery rate is less than 50%, deformation of the pressure-sensitive adhesive layer is not well restored, so that birefringence generated in the pressure-sensitive adhesive can not be eliminated and light leakage can not be prevented . In the pressure-sensitive adhesive composition for an optical film according to the present embodiment, the strain recovery ratio is preferably 50% or more, more preferably 70% or more, from the viewpoint that the birefringence generated in the pressure- desirable.

In the present invention, the " strain (%) " at any point is calculated as follows: {circumferential moving amount M (탆) of? 8 mm jig installed in the rheometer} / {thickness (占 퐉)} 占 100 (%) (see Fig. 3).

The " maximum strain " and " strain recovery ratio " in the present invention will be described with reference to Fig. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph schematically illustrating the time-course change of strain of a pressure-sensitive adhesive composition for an optical film according to the present embodiment measured using a rheometer. That is, FIG. 1 shows the measurement results of the viscoelasticity (rheology characteristic) of the pressure-sensitive adhesive composition for an optical film according to the present embodiment in the order of the measurement steps 1 to 3 using a rheometer. That is, the strain of the pressure-sensitive adhesive composition for an optical film according to the present embodiment is a value measured using a rheometer.

Measuring steps 1 to 3 are imitations of deformation that occurs over a long period of time when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition for an optical film according to the present embodiment is formed on the surface of the adherend.

In the measuring step 1, the temperature and the shearing stress of the sample piece are increased at a constant rate for a predetermined time (15 minutes). In the measuring step 2, the specimen is held at a constant temperature (80 DEG C) and a constant shear stress (1000 Pa). In the measuring step 3, the temperature and the shearing stress of the sample are reduced at a constant rate for a predetermined time (15 minutes).

1, the strain continues to increase during the measurement steps 1 and 2, and the strain becomes maximum (maximum strain) at the end of the measurement step 2 (the strain at the time when the strain reaches the maximum is the maximum strain) . Thereafter, in the measuring step 3, the strain and the shear stress together with the strain are reduced, and at the end of the measuring step 3, the strain in the measuring step 3 becomes minimum (final strain). From the final strain and the maximum strain, the strain restoration rate is calculated based on the equation (1).

1.2. (A) Component

In the present invention, the term "acrylic polymer" refers to a polymer containing at least one member selected from acrylic acid, an acrylate, an acrylate, a methacrylate, a methacrylate, and a methacrylate in an amount of at least 50 mass% . In the present invention, "(meth) acrylic acid" is a concept including acrylic acid and methacrylic acid. In the present invention, the "crosslinkable functional group" refers to a functional group capable of reacting with the crosslinking agent (B). More specifically, at least one functional group selected from a hydroxyl group, a carboxyl group, an amino group, an amide group, and an acid anhydride group The term of the species.

The content of the component (A) in the pressure-sensitive adhesive composition according to the present embodiment may be 90 to 99.99 parts by mass, preferably 95 to 99.8 parts by mass based on 100 parts by mass of the pressure-sensitive adhesive composition according to the present embodiment.

(Meth) acrylic acid ester (a1) (hereinafter simply referred to as "(a1)") having no cross-linkable functional group and having a glass transition temperature (Tg) of 0 ° C or higher in the pressure-sensitive adhesive composition according to the present embodiment, (Meth) acrylic acid ester (a2) having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 占 폚 (hereinafter, simply referred to as "(a2 ) Component (hereinafter, sometimes referred to as "component (a3)") of from 44.5 to 94.5 mass% and a monomer (a3) having a crosslinkable functional group ≪ / RTI >

1.2.1. (a1) Component

The component (a1) may be, for example, a (meth) acrylate ester having a Tg of 0 ° C or more represented by the following general formula (1).

[Chemical Formula 1]

(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched alkyl group, a pericyclic group or an aromatic ring-containing group)

(meth) acrylate ester having a Tg of 0 ° C or more, which is a component (a1), includes, for example, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate , (meth) acrylic acid alkyl esters having a linear alkyl group at an ester moiety such as n-hexadecyl acrylate, n-hexadecyl methacrylate, stearyl acrylate, and stearyl methacrylate;

(meth) acrylic acid alkyl ester having a branched alkyl group at an ester moiety such as t-butyl acrylate, i-propyl methacrylate, i-butyl methacrylate, and t-butyl methacrylate;

(Meth) acrylic acid alkyl esters having an alicyclic group at an ester moiety such as cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate and isobornyl methacrylate;

Benzyl methacrylate, benzyl acrylate, 2-naphthyl acrylate and the like, and (meth) acrylic acid alkyl esters having aromatic ring groups at the ester moiety. One of these may be used singly or in combination of two or more thereof . Among them, the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to the present embodiment is preferably a (meth) acrylic acid alkyl ester, and the (meth) acrylic acid The alkyl chain constituting the alkyl ester portion of the alkyl ester is preferably an alkyl chain of a linear or branched type, more preferably a branched alkyl chain. In this case, the number of carbon atoms in the alkyl chain is preferably from 1 to 20 (preferably from 1 to 10, more preferably from 1 to 10, more preferably from 1 to 10, ) Is more preferable.

If the content of the component (a1) in the monomer mixture for obtaining the polymer as the component (A) is less than 5% by mass, the light leakage may not be sufficiently suppressed. On the other hand, if the content is more than 55% by mass, The layer is excessively hardened, which may adversely affect the adhesive workability or the durability. In order to obtain a pressure-sensitive adhesive layer which suppresses light leakage sufficiently and is excellent in durability, the content of the component (a1) in the monomer mixture for obtaining the polymer as the component (A) is preferably 5 to 55% by mass, More preferably 10 to 40% by mass.

1.2.2. (a2) Component

The component (a2) may be, for example, a (meth) acrylate ester represented by the following general formula (2) and having a Tg of less than 0 占 폚.

(2)

(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched alkyl group, a pericyclic group or an aromatic ring-containing group)

Examples of the (meth) acrylic acid ester having a Tg of less than 0 占 폚, which is the component (a2), include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, , n-hexyl methacrylate, n-pentyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, (Meth) acrylic acid alkyl ester having a linear alkyl group at an ester moiety such as tetradecyl methacrylate; having a branched alkyl group at an ester moiety such as isopropyl acrylate, isopropyl acrylate, i-butyl acrylate, i-octyl acrylate, i-octyl methacrylate, 2-ethylhexyl acrylate, Methacrylic acid alkyl ester; (Meth) acrylic acid alkyl ester having an aromatic ring group at an ester moiety such as phenoxy ethyl acrylate, and these may be used singly or in combination of two or more kinds. Among them, the (a2) component is preferably a (meth) acrylic acid alkyl ester in which the pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition according to the present embodiment can further reduce light leakage, The alkyl chain constituting the ester moiety is preferably a linear or branched alkyl chain, more preferably a linear alkyl chain. In this case, the number of carbon atoms in the alkyl chain is preferably from 1 to 20 (preferably from 1 to 10, more preferably from 1 to 10, more preferably from 1 to 10, ) Is more preferable.

If the content of the component (a2) in the monomer mixture for obtaining the polymer as the component (A) is less than 44.5 mass%, the balance of the adhesive property may be broken and the adhesion to the adherend may be insufficient. On the other hand, , There is a case where light leakage can not be sufficiently suppressed. In order to obtain a pressure-sensitive adhesive layer which sufficiently suppresses light leakage and is excellent in durability, the content of the component (a2) in the monomer mixture for obtaining the polymer as the component (A) is preferably 44.5 to 94.5% by mass, More preferably 50 to 89.5% by mass, and still more preferably 60 to 86% by mass.

1.2.3. (a3) Component

The component (a3) is a monomer other than the component (a1) and the component (a2), and has a crosslinkable functional group. Examples of the component (a3) include, for example, carboxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, acrylamide, N, N-dimethylamino Propyl acrylamide, acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide and acrylonitrile. Of these, one or two or more kinds of monomers having a crosslinkable functional group as essential ones may be used in combination . Among these, the component (a3) is preferably an alkyl (meth) acrylate and an alkyl amide having a crosslinkable functional group, or an alkyl group having a crosslinking functional group, from the viewpoint of excellent crosslinking performance with the crosslinking agent as the component (B) (Meth) acrylate, acrylic acid, and alkyl amide.

1.2.4. The total amount of the component (a1), the component (a2) and the component (a3)

In the pressure-sensitive adhesive composition according to the present embodiment, from the viewpoint of achieving a predetermined maximum strain and strain recovery ratio, the component (a1), the component (a2) and the component (a3) may be 90 to 100 mass%, preferably 95 to 100 mass%.

In addition, the pressure-sensitive adhesive composition according to the present embodiment has a content of a monomer having an alkylene oxide group of 5% by mass or less in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to the present embodiment can further reduce light leakage And it is more preferable that it does not contain a monomer having an alkylene oxide group. Examples of the monomer having an alkylene oxide group include a reactive emulsifier having a (meth) acryl monomer and an alkylene oxide group having an alkylene oxide group in the side chain. In the present invention, "the pressure-sensitive adhesive composition does not contain a monomer having an alkylene oxide group" means that the content of a monomer having an alkylene oxide group in the pressure-sensitive adhesive composition is 2% by mass or less. In particular, the content of the monomer having an alkylene oxide group in the pressure-sensitive adhesive composition is preferably 0 to 2% by mass.

1.2.5. Tg

In the pressure-sensitive adhesive composition according to the present embodiment, it is preferable that the Tg of the component (A) is from -70 to 0 캜, from the viewpoint of preventing light leakage and increasing durability by achieving a predetermined maximum strain and strain recovery ratio And more preferably -40 to -10 ° C. Further, in the present invention, the Tg of the component (A) is a value calculated by the following formula (2) (formula of FOX).

1 / Tg _A = W _a1 / Tg _a1 + W _a2 / Tg _a2 + W _a3 / Tg _a3 ... (2)

Wherein Tg _A represents the glass transition temperature (K) of the component (A), and Tg _a1 , Tg _a2 and Tg _a3 represent the glass transition temperature of the homopolymer prepared from the constituent monomers (a1), (a2) represents the glass transition temperature (Tg (K)), W _a1, W _{a2, a3} W represents the weight fraction of monomer configuration (a1), (a2), (a3) contained in the component (a), respectively)

Further, according to the above equation (2), since Tg _A is calculated as the absolute temperature K, it is converted to the Celsius temperature (占 폚) as needed.

The glass transition temperature of a homopolymer prepared from a typical monomer is shown in Table 1 below. More specifically, it is described in, for example, Polymer Handbook Third Edition (Wiley-Interscience, 2003) .

1.2.6. Weight average molecular weight (Mw)

In the pressure-sensitive adhesive composition according to the present embodiment, the component (A) has a weight average molecular weight (Mw) of from 1 to 20, preferably from 1 to 10, and more preferably from 1 to 10, in terms of preventing light leakage and increasing durability, It is preferably from 500,000 to 2,000,000, more preferably from 800,000 to 1,800,000. Here, the weight average molecular weight (Mw) of the component (A) was determined by GPC (gel permeation chromatography) under the following conditions in terms of standard polystyrene.

≪ GPC measurement condition >

Measuring apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC Column Composition: The following five columns (all manufactured by Toso Co., Ltd.)

(1) TSK-GEL HXL-H (Guide column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: 1.0 mg / cm3, diluted with tetrahydrofuran

Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0 cm3 / min

Column temperature: 40 DEG C

It is preferable that the component (A) according to the present embodiment has a molecular weight distribution (weight average molecular weight / number average molecular weight) determined by GPC in the range of 4 to 7.

1.2.7. Gel fraction

From the standpoint of preventing light leakage and increasing durability by achieving a predetermined maximum strain and strain recovery ratio in the pressure-sensitive adhesive composition according to the present embodiment, the pressure-sensitive adhesive composition of the present embodiment has a gel fraction of 70 Or more, more preferably 77% or more.

In the pressure-sensitive adhesive composition according to the present embodiment, the gel fraction may be determined depending on, for example, the kind and amount of the component (a3) in the monomer mixture used in preparing the pressure-sensitive adhesive composition, the type and amount of the cross- Can be adjusted. The gel fraction was obtained by taking 0.1 g (dry weight (1)) of the cross-linked pressure-sensitive adhesive on a dry weight basis, further adding 30 cc of ethyl acetate to the sample bottle, shaking it for 24 hours, The contents of the sample bottle were separated by filtration through a 200 mesh stainless steel wire net and the residue on the wire net was dried at 100 占 폚 for 2 hours to measure the dry weight (dry weight (2)) and was determined by the following formula (3) .

Gel fraction (%) = (dry weight (2) / dry weight (1)) × 100 (3)

1.3. Component (B)

In the pressure-sensitive adhesive composition according to the present embodiment, the crosslinking agent as the component (B) is not particularly limited as long as it is a crosslinking agent capable of crosslinking with the component (A) at ordinary temperature or under heating. Examples thereof include isocyanate crosslinking agents, Chelate crosslinking agents, and isocyanate crosslinking agents.

Specific examples of the isocyanate crosslinking agent include xylylene diisocyanate, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenyl And isocyanate monomers such as methane diisocyanate, and isocyanate compounds and isocyanurate compounds obtained by subjecting them to an addition reaction with a divalent or higher alcohol compound such as trimethylolpropane.

Also, urethane prepolymer type isocyanates obtained by subjecting an isocyanate compound to addition reaction with known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols and the like can be given. Of these, xylylene diisocyanate and derivatives thereof are preferably used. When the component (A) has a carboxyl group, an isocyanate-based crosslinking agent and an epoxy crosslinking agent may be used in combination.

The content of the component (B) in the pressure-sensitive adhesive composition according to the present embodiment is preferably such that the content of the component (B) is 100 parts by mass or more, 0.01 to 3 parts by mass, and preferably 0.1 to 1.5 parts by mass.

1.4. Other Ingredients

The pressure-sensitive adhesive composition for an optical film according to the present embodiment may further contain components other than the components (A) and (B), if necessary. For example, the pressure-sensitive adhesive composition according to the present embodiment may contain (C) a silane coupling agent (hereinafter sometimes simply referred to as "component (C)"), (D (Hereinafter sometimes simply referred to as " component (D) "), an antioxidant, an ultraviolet absorber, a tackifier, and a plasticizer.

1.4.1. (C) Silane coupling agent

When the pressure-sensitive adhesive composition for an optical film according to the present embodiment contains the component (C), when a pressure-sensitive adhesive layer is formed on the surface of the adherend using the pressure-sensitive adhesive composition for an optical film according to the present embodiment, It can be kept good. The component (C) includes, for example, a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane; Silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; And 3-chloropropyltrimethoxysilane; An oligomer-type silane coupling agent, and the like. Among them, a silane coupling agent having a functional group reactive with a functional group contained in the (meth) acrylic copolymer (A) is preferable because it does not easily cause peeling under a humid environment.

The content of the component (C) in the pressure-sensitive adhesive composition for an optical film according to the present embodiment is preferably within a range of from about 100 parts by mass to about 100 parts by mass with respect to 100 parts by mass of the pressure- May be 0 to 0.5 parts by mass, and preferably 0.05 to 0.3 parts by mass.

1.4.2. (D) an ionic compound

The pressure-sensitive adhesive composition according to the present embodiment may contain an ionic compound (D). When the pressure-sensitive adhesive composition according to the present embodiment contains the component (D), when the pressure-sensitive adhesive composition according to the present embodiment is used to form a pressure-sensitive adhesive layer on the surface of an adherend, charging of the adherend can be effectively prevented. Examples of the component (D) include ionic compounds which are in the form of liquid or solid at 25 占 폚 comprising anion and cation, and specifically include alkali metal salts, ionic liquids (liquid at 25 占 폚) , A surfactant, and the like.

Examples of the alkali metal salt include an alkali metal cation such as lithium, sodium, potassium, and an anion. Specific examples of the alkali metal salt include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, potassium chlorate, sodium carbonate, sodium thiocyanate, sodium, LiBr, LiI, LiBF _4, LiPF _6, LiSCN, sodium acetate, sodium alginate, lignin sulfonate, toluene _{sulfonate, LiCF 3 SO 3, Li (} CF 3 SO 2) 2 N, Li (CF ₃ SO ₂ ) IN, Li (C ₂ F ₅ SO ₂ ) 2N, Li (C ₂ F ₅ SO ₂ ) IN and Li (CF ₃ SO ₂ ) ₃ C.

Examples of the cation that constitutes the ionic liquid include piperidinium cation, pyrrolidinium cation, cation having a pyrrolene skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium Examples of the cationic cationic surfactant include cationic cationic surfactants such as cationic surfactants, cationic surfactants, cationic surfactants, cationic surfactants, cationic surfactants, cationic surfactants, cationic surfactants, cationic surfactants, The anions constituting the liquid include Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CF _{^{3 COO -, CH 3 SO 3}} -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, NbF 6 -, TaF 6 ^{-, F (HF) n -} (n = 2 ~ 3), (CN) 2 n -, C 4 F 9 SO 3 -, (C 2 F 5 SO 2) 2 n -, C 3 F 7 COO -, (CF ₃ SO ₂ ) (CF ₃ CO) N ^- and the like.

Examples of the ionic compound include an ionic compound which is composed of these cation and anion and is in a liquid phase at 25 占 폚. Specific examples of such ionic compounds include 2-methyl-1-pyrrolin tetrafluoroborate, 1-ethyl-2-phenyl indole tetrafluoroborate, 1,2-dimethyl indole tetrafluoroborate, 1 Ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate Ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate , 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, (Trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl- Imidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluoro Butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis Methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1 3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl- 3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-di 3-propylimidazolium bis (trifluoromethanesulfonyl) imide, 1-methylpyrazolium tetrafluoroborate, 3-methylpyrazolium tetrafluoroborate, tetrahexylammonium bis (trifluoromethanesulfonyl) imide, Diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium bis (pentafluoro) N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluoro Methanesulfonate, glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide, glycidyltrimethylammonium bis (pentafluoroethanesulfonyl) imide, 1-butylpyridinium (trifluoromethanesulfonyl) ) Trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-3-methylimidazolium (trifluoromethanesulfonyl) (2-methoxyethyl) ammonium (trifluoromethanesulfonyl) trifluoroacetamide, diallyldimethylammonium (trifluoromethanesulfonyl) amide, N, ) Trifluoroacetamide, glycidyltrimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-dimethyl-N-ethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfo N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-butylammonium bis (triphenylmethanesulfonyl) imide, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl- (Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoromethanesulfonyl) Ammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-heptylammonium bis N, N-dimethyl-N-pentyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, Trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, (Trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, triethylpropylammonium bis (trifluoromethanesulfonyl) imide, tri (Trifluoromethanesulfonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammonium bis Lometasulfonyl) imide N, N-dipropyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl- N, N-dibutylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl- N, N-dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide.

As the surfactant, any of a nonionic surfactant, a cationic surfactant, an anionic surfactant and an amphoteric surfactant can be used.

Examples of the nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether, Sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monolaurate, sorbitan monolaurate, sorbitan monostearate and sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; Polyoxyethylene higher fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monostearate; Examples thereof include glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride, and polyoxyalkylenes such as polyoxyethylene, polyoxypropylene and polyoxybutylene, and block copolymers thereof.

Examples of the cationic surfactant include alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzalkonium chloride salt, and alkyldimethylammonium ethosulfate.

Examples of the anionic surfactant include carboxylates such as sodium laurate, sodium oleate, N-acyl-N-methylglycine sodium salt and sodium polyoxyethylene lauryl ether carboxylate, sodium dodecylbenzenesulfonate, di Sulfonic acid salts such as alkylsulfosuccinic acid ester salts and sodium dimethyl-5-sulfoisophthalate, sulfuric acid ester salts such as sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene nonylphenyl ether sulfate, polyoxyethylene lauryl Phosphoric acid ester salts such as sodium phosphate, polyoxyethylene nonylphenyl ether phosphate and the like.

Examples of the amphoteric surfactant include carboxybetaine type surfactants, aminocarboxylic acid salts, imidazolinium betaines, lecithin and alkylamine oxides. In addition, a conductive polymer, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, and the like may be used.

Of these, alkali metal salts are preferable, and lithium perchlorate is particularly preferably used.

The content of the component (D) in the pressure-sensitive adhesive composition for an optical film according to the present embodiment may be 0 to 3 parts by mass, preferably 0.05 to 2.5 parts by mass, per 100 parts by mass of the pressure- Do.

1.5. Method of polymerization of component (A)

The method of polymerizing the component (A) is not particularly limited, and it can be polymerized by a known method such as solution polymerization, emulsion polymerization, suspension polymerization, etc. By using the mixture of the copolymer obtained by the polymerization, It is preferable to polymerize by solution polymerization from the viewpoint that the treatment process is relatively simple and can be carried out in a short time.

Solution polymerization is generally carried out by heating and reacting with a predetermined organic solvent, a monomer, a polymerization initiator, a chain transfer agent and the like, which are used as needed, in a polymerization vessel, while stirring under a nitrogen stream or an organic solvent at a reflux temperature .

In this case, at least a part of the organic solvent, the monomer and / or the polymerization initiator may be added sequentially. Examples of the organic solvent include organic solvents such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, Aromatic hydrocarbons; Examples thereof include aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha and turpentine; For example, esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate and methyl benzoate; Ketones such as acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, and methylcyclohexanone; For example, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether; Examples thereof include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol. These organic solvents may be used alone or in combination of two or more.

Among these organic solvents for polymerization, it is preferable to use an organic solvent (for example, esters and ketones) which does not generate chain transfer well during the polymerization reaction in the polymerization of the component (A) The use of ethyl acetate, methyl ethyl ketone, acetone or the like is preferable in view of the solubility of the reaction mixture and the ease of polymerization.

As the polymerization initiator, it is possible to use organic peroxides, azo compounds and the like that can be used in ordinary solution polymerization. Examples of such organic peroxides include t-butyl hydroperoxide, cumene hydrooxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, Bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di- (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-a-cumylperoxycyclo (4,4-di-t-butylperoxycyclohexyl) butane, 2,2-bis (4,4- Azo compounds such as 2,2'-azobis-i-butyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis -4-methoxy-2,4-dimethylvaleronitrile, and the like.

Among these organic peroxides, a polymerization initiator which does not cause a graft reaction during the polymerization reaction of the component (A) is preferable, and an azo system is particularly preferable. The amount to be used is usually 0.01 to 2 parts by weight, preferably 0.1 to 1.0 part by weight based on 100 parts by weight of the total amount of the monomers.

In the production of the component (A) contained in the pressure-sensitive adhesive composition of the present invention, a chain transfer agent is usually not used, but it can be used as needed within a range not hindering the object and effect of the present invention.

Such chain transfer agents include, for example, cyanoacetic acid; Alkyl esters of 1 to 8 carbon atoms in cyanoacetic acid; Bromoacetic acid; Alkyl esters of bromoacetic acid having 1 to 8 carbon atoms; Aromatic compounds such as anthracene, phenanthrene, fluorene, and 9-phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol and p-nitrotoluene; Benzoquinone derivatives such as benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone; Borane derivatives such as tributylborane; Halogenated compounds such as carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichlorethylene, bromotrichloromethane, tribromomethane and 3-chloro-1- Hydrocarbons; Aldehydes such as chloral and furaldehyde; alkylmercaptans having 1 to 18 carbon atoms; Aromatic mercaptans such as thiophenol and toluene mercaptan; Mercaptoacetic acid, alkyl esters having 1 to 10 carbon atoms in mercaptoacetic acid; Hydroxyalkylmercaptans having 1 to 12 carbon atoms; Terpenes such as pinene and terpinolene, and the like.

The polymerization temperature of the component (A) is generally about 30 to 180 占 폚, preferably 40 to 150 占 폚, and more preferably 50 to 90 占 폚. When the unreacted monomer is contained in the polymer obtained by the solution polymerization method or the like, it may be purified by a reprecipitation method using methanol or the like in order to remove the monomer.

1.6. Preparation of pressure-sensitive adhesive composition

The pressure-sensitive adhesive composition according to the present embodiment is usually prepared by mixing the components (A) and (B) and optional components as needed, either simultaneously or in any order. When the component (A) is prepared by solution polymerization in the mixing of the component (A) and the component (B), the component (B) may be added to the solution containing the component (A) When component (A) is prepared by bulk polymerization, it is difficult to uniformly mix after completion of polymerization, and therefore it is preferable to add component (B) during the polymerization to mix.

1.7. Uses and effects

The pressure-sensitive adhesive composition according to the present embodiment can be preferably used as an adhesive for an optical film (to be described in detail later). The pressure-sensitive adhesive composition according to the present embodiment exhibits excellent durability under high-temperature and high-humidity conditions. In addition, when used for adhering an adherend such as a liquid crystal cell and an optical film such as a polarizing film, light leakage can be reduced . In the case where the image display apparatus includes a retardation film, an adhesive layer using the pressure-sensitive adhesive composition according to the present embodiment can be formed between the retardation film and the polarizing film because a retardation film is formed between the liquid- have.

For example, in an image display device (liquid crystal display device) of an LED system employing an LED as a light source, a pressure-sensitive adhesive composition according to the present embodiment is used for adhesion of an adherend such as a liquid crystal cell and an optical film such as a polarizing film , It is possible to realize a good light leakage preventing property and a high durability, so that the image quality of the image display device can be improved. In this case, the pressure-sensitive adhesive composition according to the present embodiment can be used as an adhesive to which a polarizing film for VA mode or a polarizing film for IPS mode is adhered, but in view of achieving high image quality, It can be preferably used as an adhesive.

For example, when the pressure-sensitive adhesive composition according to the present embodiment is used as an adhesive to which a polarizing film for VA mode is applied as an adherend, a large (for example, 10 inch or larger, preferably 19 inch or larger) image display device In the case of using the pressure-sensitive adhesive composition according to the present embodiment for forming the adhesive layer, since the shrinkage of the polarizing film is particularly large in a large-sized image display apparatus, the effect of lifting and peeling due to the influence of stress caused by dimensional deformation is large , The light leakage due to the deformation of the polarization axis is large. Therefore, the adhesive layer is excellent in durability and can be reduced in light leakage, which is advantageous in achieving high image quality.

It is presumed that the light leakage preventing property, which is a mono-action effect of the pressure-sensitive adhesive composition according to the present embodiment, is due to the following two mechanisms of action. First, when the stress resulting from the shrinkage of the polarizing film is applied to the pressure-sensitive adhesive composition according to the present embodiment, the strain of the pressure-sensitive adhesive composition according to the present embodiment is small (the maximum strain of the pressure- Or less), the shrinkage of the polarizing film can be appropriately suppressed, the deformation of the polarization axis of the polarizing film can be reduced, and as a result, the light leakage can be reduced. Secondly, when the stress of the polarizing film is released, the deformation restoration rate of the pressure-sensitive adhesive composition according to the present embodiment is 50% or more, so that the deformation of the pressure-sensitive adhesive composition related to the present embodiment is quickly restored. So that the light leakage of the image display device can be reduced.

That is, when a pressure-sensitive adhesive layer is formed on the surface of an optical film (polarizing film) using the pressure-sensitive adhesive composition according to the present embodiment, the strain of the pressure-sensitive adhesive layer is small (the maximum strain of the pressure- (The strain recovery ratio of the pressure-sensitive adhesive composition relating to the present embodiment is at least 50%), in which the shrinkage of the optical film is appropriately suppressed, and the second characteristic in which the deformation of the pressure- The pressure-sensitive adhesive composition according to the present embodiment is provided, so that high durability of the image display device can be realized and light leakage of the image display device can be reduced.

2. Adhesive type optical film and laminate

2.1. Adhesive optical film

In the adhesive optical film according to another embodiment of the present invention, a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition for an optical film according to the above embodiment is formed on one side or both sides of the optical film. In producing the pressure-sensitive adhesive optical film according to the present embodiment, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition on an optical film by a gravure coater, a Meyer bar coater, an air knife coater, a roll coater, The applied pressure-sensitive adhesive composition may be formed by drying and crosslinking at room temperature or by heating, or may be formed by forming a pressure-sensitive adhesive layer on a release film and transferring the pressure-sensitive adhesive layer onto the optical film. The thickness of the pressure-sensitive adhesive layer is usually 1 to 50 占 퐉, preferably 5 to 30 占 퐉. Prior to use of the adhesive optical film, a release film may be laminated on the surface of the pressure-sensitive adhesive layer in order to protect the pressure-sensitive adhesive layer.

The adhesive optical film according to the present embodiment can be used in an image display apparatus such as an FPD, and includes, for example, a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, And an optical film selected from the group consisting of films. The thickness of the optical film may be appropriately selected depending on the intended use, but is usually from 10 to 500 탆, preferably from 15 to 300 탆.

2.2. The laminate

The laminate related to one embodiment of the present invention comprises a glass substrate, a polarizing plate, and a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) formed by molding a pressure-sensitive adhesive composition for an optical film according to the above embodiment formed between the glass substrate and the polarizing plate and heating Sheet).

2.2.1. Laminated structure

4 is a cross-sectional view schematically showing an example of a laminate (laminate 200) according to an embodiment of the present invention. 1, the laminate 200 includes a glass substrate 110, a polarizing film (polarizing plate) 130, a pressure-sensitive adhesive layer 120 formed between the glass substrate 110 and the polarizing film 130, .

More specifically, the laminate 200 includes a glass substrate 110, a pressure-sensitive adhesive layer 120 formed on the glass substrate 110, and a polarizer 120 formed on the glass substrate 110 via the pressure- Film 130 as shown in FIG. The glass substrate 110 and the polarizing film 130 are bonded to each other with the adhesive layer 120 interposed therebetween.

4, the pressure-sensitive adhesive layer 120 is formed on the surface of the adherend (glass substrate 110). As a method of forming the pressure-sensitive adhesive composition according to the present embodiment on the surface of an adherend, a pressure-sensitive adhesive composition is applied to the surface of a release film (separator) having a good smoothness and the coated film is dried, To be transferred to.

The laminate related to this embodiment is included in, for example, an image display apparatus (particularly, a liquid crystal display apparatus). In this case, the glass substrate included in the laminate related to this embodiment is a glass substrate for a liquid crystal display.

2.2.2. Glass substrate

The glass substrate constituting the laminate related to the present embodiment may be a glass substrate used for an image display apparatus. The image display device may be, for example, a TFT (thin film transistor) liquid crystal display device used in a liquid crystal television, a computer monitor, a cellular phone, a tablet, and the like.

2.2.3. Action effect

The laminate related to this embodiment is obtained by forming a pressure-sensitive adhesive composition for an optical film according to the above-described embodiment, which is formed between a glass substrate, a polarizing film and the glass substrate and the polarizing film, It is possible to exhibit excellent durability under high temperature and high humidity conditions and also to reduce light leakage.

3. Example

Hereinafter, the present invention will be described based on the following examples, but the present invention is not limited to the examples.

3.1. Preparation of the component (A)

A monomer mixture having the mixing ratios shown in Tables 2 and 3 below was poured into a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen-introducing tube, and then ethyl acetate was added to the reaction mixture at a monomer concentration of 50 mass% Lt; / RTI > Subsequently, 0.1 part by mass of azobisisobutyronitrile was added, stirring was performed while air in the reaction vessel was replaced with nitrogen gas, the temperature was raised to 60 占 폚, and the reaction was carried out for 4 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate to obtain a component (A) (acrylic polymers A to L).

3.2. Manufacture of Polishing Plate for Adhesive Process for Evaluation

3.1. The components (A) obtained in (1) and (2) were added to each of the components shown in Tables 3 and 4 to obtain a solution of the pressure-sensitive adhesive compositions of Examples 1 to 15 and Comparative Examples 1 to 5. The solution of the pressure-sensitive adhesive composition was coated on the surface of the exfoliated polyester film and dried to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 20 占 퐉. This adhesive sheet was attached to one side of the polarizing film for VA mode and aged for 7 days in a dark place under the condition of 23 캜 / 50% RH to obtain an adhesive working polarizing plate for evaluation.

For each evaluation adhesive working polarizing plate, the maximum strain, deformation restoration rate, light leakage (using a LED as a light source: LED method), light leakage (not using an LED as a light source, LED method), and wet heat resistance (foaming and thermal insulation) were evaluated by the following methods.

3.3. Assessment Methods

3.3.1. Maximum strain and strain recovery

The acrylic copolymer solutions of Examples 1 to 15 and Comparative Examples 1 to 5 shown in Tables 3 and 4 were coated on the surface of the peeled polyester film and dried to form a film with a thickness of 1 mm , And cut into? 8 mm to obtain a test piece. The test pieces were subjected to the above-mentioned measuring steps 1 to 3 in order by using a rheometer (model name: MCR300, manufactured by Seibe Hagner Co., Ltd.) to measure the maximum strain, and the strain recovery rate Respectively.

3.3.2. Light leakage

A pressure-sensitive adhesive process polarizing plate for evaluation, in which a peeled polyester film was peeled off, was laminated on a 19-inch VA type liquid crystal panel (manufactured by I / O Data Corporation, type: LCD-A191EW) The sample was allowed to contact in the atmosphere at 80 캜 for 240 hours, and then allowed to stand at 23 캜 / 50% RH for 2 hours. Thereafter, the VA type liquid crystal panel in which the polarizing plate was laminated was connected to a personal computer in a dark room to obtain full-screen black display. In this test, evaluation was conducted using two kinds of light sources (backlight), namely, an LED (LED method) and a fluorescent lamp (non-LED method). 2, the brightness (La, Lb, Lc, Ld) in the area of 1 cm in diameter in the vicinity of each corner and the area of 1 cm in diameter in the central part of the monitor (Lcenter) was measured using a luminance meter (model name: RISA-COLOR / CD8, manufactured by Highland Corporation) and the light leakage property? L was calculated based on the following equation (4). The smaller ΔL means less light leakage (from the backlight), and generally, when ΔL is less than 2.0, it can be used as a liquid crystal display panel.

L = (La + Lb + Lc + Ld) / 4 - Lcenter ... (4)

In addition, as shown by the dotted line in Fig. 2, the range R where the light leakage occurred near the corner of the display monitor was visually measured. The smaller the range in which the light leakage occurs, the smaller the light leakage. Generally, when R is less than 20 mm, it can be used as a liquid crystal display panel.

3.3.3. Moist heat durability

An adhesive process polarizing plate for peeling off the peeled polyester film was cut to a size of 15 inches (233 mm 309 mm), and a pressure-sensitive adhesive layer was brought into contact with the glass plate on one side of a non-alkali glass plate with a thickness of 0.5 mm, Using a roll. After the application, the plate was subjected to pressure treatment with an autoclave (manufactured by Kurihara Seisakusho) under the conditions of 0.5 MPa and 50 캜 for 20 minutes to obtain a test plate. The test plate thus obtained was allowed to stand under the condition of 60 占 폚 / 90% RH for 500 hours. After completion of the test, the test plate was taken out of the test environment and allowed to stand under an atmosphere of 23 ° C / 50% RH for 2 hours. Thereafter, the foaming (lack of cohesion) and adiabatic (and crosslinking) Were evaluated by the following evaluation criteria.

(Foam-size)

○: No foaming is observed at all

DELTA: The diameter of the foam was not more than 1 mm

X: The expansion diameter is larger than 1 mm

(Foam-generated amount)

○: No foaming is observed at all

: The number of foams was 10 or less

X: Number of foams is more than 10

(Insulation - Size)

○: Insulation is not observed at all

?: Less than 5% of the total area (100%) of the fusion region in the test plate

X: The area where the heat insulation occurred was not less than 5% (100%) with respect to the entire joining portion in the test plate

(Insulation - Position)

○: No insulation

?: Only one-cm-wide region near each end of the test plate has defects

X: There are defects other than the 1 cm area and the area near each end of the test plate.

The abbreviations in Tables 2, 3 and 4 have the following meanings.

AA: Acrylic acid

AM: acrylamide

BA: n-butyl acrylate

t-BA: tertiary butyl acrylate

i-BMA: isobutyl methacrylate

HEA: 2-hydroxyethyl acrylate

L-45: TDI isocyanate compound (L-45 manufactured by Soken Chemical & Engineering Co., Ltd.)

MA: methyl acrylate

MEA: methoxyethyl acrylate

i-PMA: isopropyl methacrylate

TD: XDI isocyanate compound (TD-75 manufactured by Mitsui Takeda Chemical Industries, Ltd.)

KBM-403: 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.)

Antistatic agent (component (D): ionic compound): 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide

From the results of Tables 1 to 4, it can be seen that the compositions of Examples 1 to 15 have a maximum strain of 10% or less and a strain recovery rate of 50% or more, whereby the adhesive layer obtained by using the composition can shrink the optical film The pressure-sensitive adhesive composition according to the present embodiment is provided with both the first property for suppressing the pressure-sensitive adhesive layer and the second property for promptly restoring the deformation of the pressure-sensitive adhesive layer, thereby achieving high adhesive strength and excellent durability, . On the other hand, in the compositions of Comparative Examples 1 to 6, since the maximum strain is 10% or less and the strain recovery ratio is not more than 50%, the adhesive layer obtained by using the composition is not the first It is understood that the reduction of the light leakage can not be sufficiently achieved because the characteristics and the second characteristics are not compatible with each other.

1: sample piece
2: Jig
10: Final strain
20: Maximum strain
100: Image display device
La, Lb, Lc, and Ld: luminance near the corner of the image display device
Lcenter: Luminance at the center of the image display device
M: Circumference movement amount
T: thickness of sample piece
110: glass substrate
120: pressure-sensitive adhesive layer
130: polarizing film
200: laminate

Claims (10)

(A) an acrylic polymer having a crosslinkable functional group, and a crosslinking agent (B)
The maximum strain defined below is 10% or less, and the strain recovery ratio defined below is 50% or more.
Maximum strain: A pressure-sensitive adhesive sheet having a thickness of 1 mm obtained by applying the pressure-sensitive adhesive composition for an optical film on a flat plate and drying the pressure-sensitive adhesive sheet was cut into 8 mm, and the following test pieces 1 to 3 were measured (%) At the time when the strain becomes maximum,
Final strain: Strain (%) of the test piece after the following measuring steps 1 to 3 were carried out in sequence using a rheometer.
Deformation recovery rate: A value obtained by applying a pressure-sensitive adhesive sheet for optical film to a test piece obtained by applying a pressure-sensitive adhesive composition for an optical film on a flat plate and drying the pressure-sensitive adhesive sheet cut to a thickness of 8 mm,
Strain recovery rate (%) = (maximum strain - final strain) / maximum strain x 100 ... (One)
Measuring Step 1: While increasing the temperature of the sample piece from 23 DEG C to 80 DEG C for 15 minutes at a constant rate, the shearing stress of the sample piece is increased from 0 Pa to 1000 Pa for 15 minutes at a constant rate
Measuring Step 2: While maintaining the temperature of the sample piece at 80 占 폚 for 30 minutes, the shear stress is increased from 1000 Pa to 2000 Pa at a constant rate for 30 minutes
Measuring Step 3: The shearing stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes while the temperature of the sample piece is decreased from 80 캜 to 23 캜 at a constant rate for 15 minutes. The method according to claim 1,
The acrylic polymer (A) having a crosslinkable functional group,
(Meth) acrylic acid ester (a1) having no crosslinkable functional group and having a glass transition temperature (Tg) of 0 占 폚 or more,
44.5 to 94.5 mass% of a (meth) acrylic acid ester (a2) having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 占 폚,
Wherein the total amount of the monomer mixture (a1), (a2) and (a3) in the monomer mixture is from 90 to 100 mass% %). ≪ / RTI > 3. The method according to claim 1 or 2,
Wherein the (meth) acrylic acid ester (a1) is a (meth) acrylic acid alkyl ester,
Wherein the alkyl chain constituting the alkyl ester portion of the (meth) acrylic acid alkyl ester (wherein the number of carbon atoms of the alkyl chain is from 1 to 20) is a linear or branched alkyl chain. 4. The method according to any one of claims 1 to 3,
The acrylic polymer (A) having a crosslinkable functional group has a Tg of -70 to 0 占 폚. 5. The method according to any one of claims 1 to 4,
The acrylic polymer (A) having a crosslinkable functional group has a weight average molecular weight of 500,000 to 2,000,000. 6. The method according to any one of claims 1 to 5,
A pressure-sensitive adhesive composition for an optical film having a gel fraction of 70% or more. (A) an acrylic polymer having a crosslinkable functional group, and a crosslinking agent (B)
The acrylic polymer (A) having a crosslinkable functional group,
(Meth) acrylic acid ester (a1) having no crosslinkable functional group and having a glass transition temperature (Tg) of 0 占 폚 or more,
44.5 to 94.5 mass% of a (meth) acrylic acid ester (a2) having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 占 폚,
Wherein the total amount of the monomer mixture (a1), (a2) and (a3) in the monomer mixture is from 90 to 100 mass% %), And a gel fraction of 70% or more. A pressure-sensitive adhesive optical film for forming the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 7 on one side or both sides of an optical film. 9. The method of claim 8,
Wherein the optical film is an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and a light diffusion film. A glass substrate,
A polarizing plate,
And a pressure-sensitive adhesive layer obtained by molding the pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 7 formed between the glass substrate and the polarizing plate and heating the film.

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