TWI627247B - Adhesive composition for optical film and adhesive type optical film - Google Patents

Abstract

The present invention provides an adhesive composition for an optical film, comprising: (A) an acrylic polymer, which includes (a1) a (meth) acrylate monomer having a specific structure and (a2) having 1 in the molecule. A polymer of a monomer mixture of an olefinic double bond and a monomer having at least one hydroxyl group, (B) a crosslinking agent having a specific structure.

Description

Adhesive composition for optical film and adhesive optical film

The present invention relates to an adhesive composition for an optical film and an adhesive optical film.

In recent years, image display devices have been used in a variety of applications and conditions, such as not only at room temperature, but also at high temperatures, and even under severe conditions such as high temperature and humidity. Examples of use under high-temperature or high-temperature and humid conditions include use in a tropical region, use inside a vehicle, or use inside an outdoor measuring device.

In addition, optical films such as polarizing films constituting an image display device are manufactured by adsorbing a dye having a dichroic property onto a polymer film such as polyvinyl alcohol, and extending and aligning the polymer film. Therefore, the optical film will shrink under high temperature and humidity environment, and dimensional deformation will occur. Moreover, once the dimensional deformation of the optical film occurs, it is difficult to completely restore the original size even if the temperature and humidity conditions are changed, for example. As a result, the optical film may be cracked, peeled off, or floated due to the influence of the stress caused by the dimensional change, which may cause light leakage in the image display device due to deformation of the polarization axis.

Furthermore, in recent years, the screen size, image quality, and durability of image display devices have been required. As a result, various reviews have been performed on the adhesive composition in order to resolve appearance defects such as light leakage caused by dimensional changes of optical films such as polarizing films, peeling in high temperature and high humidity environments, and blistering.

[Prior technical literature] [Patent Document 1]

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-169329

An object of the present invention is to provide an adhesive composition for an optical film, and an adhesive optical film using the adhesive composition for an optical film. The former exhibits excellent durability under high temperature and humidity conditions, and is used for bonding When an adherend such as a liquid crystal cell or an optical film such as a polarizing film is used, light leakage can be reduced.

In order to solve such problems, the present inventors have found that when an adhesive layer is formed using an adhesive composition containing a cross-linking agent having a specific structure, and the adhesive layer is used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film, Reduce light leakage.

1. An adhesive composition for an optical film according to one aspect of the present invention, comprising: (A) an acrylic polymer including (a1) (meth) acrylic acid represented by the following general formula (1): A polymer of an ester monomer and (a2) a monomer mixture having a monomer having an olefinic double bond and at least one hydroxyl group in the molecule, and (B) the following general formula (2) or the following general formula ( 3) the crosslinking agent shown;

(Wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having a carbon number of 1 to 14),

(Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently an alkylene group containing 2 to 10 carbon atoms),

(Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently an alkylene group containing 2 to 10 carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F are independently alkylene groups containing 2 to 10 carbon atoms. Base),

(Where x is an integer from 2 to 10 and m is an integer from 1 to 10);

(In the formula, X represents a single bond or -O-, y is an integer of 2 to 10 and n is an integer of 1 to 10).

2. The adhesive composition for an optical film according to the above 1, which may contain the above-mentioned (B) crosslinking agent in an amount of 0.05 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the (A) acrylic polymer.

3. The adhesive composition for an optical film according to the above 1 or 2, wherein the monomer mixture may contain 90% by mass of the (meth) acrylate monomer represented by the general formula (1) (a1) The above is 99.9% by mass or less and (a2) the monomer having one olefinic double bond and at least one hydroxyl group in the molecule is 0.1% by mass or more and 10% by mass or less.

4. The adhesive composition for an optical film according to any one of the above 1 to 3, wherein the monomer mixture may contain (meth) acrylic acid represented by (a1-1) and (a1-2) The ester monomer is the (meth) acrylic acid ester monomer represented by the aforementioned general formula (1) in (a1): (a1-1) assuming that the glass transition temperature (Tg) in the case of forming a homopolymer is 0 ° C As described above, the (meth) acrylic acid ester monomer represented by the general formula (1) is 5 mass% or more and 55 mass% or less; (a1-2) the glass transition temperature (Tg) in the case of forming a homopolymer Less than 0 ° C, the (meth) acrylate monomer represented by the general formula (1) is 44.5% by mass or more and 94.5% by mass or less; (Wherein the total amount of (a1-1) and (a1-2) is 90.1% by mass or more and 100% by mass or less).

5. The adhesive composition for an optical film according to any one of 1 to 4 above, which may further contain 0.01 part by mass or more of the (C) silane coupling agent with respect to 100 parts by mass of the (A) acrylic polymer. 0.5 parts by mass or less.

6. The adhesive composition for an optical film according to any one of the above 1 to 5, further comprising 0.01 part by mass or more of the (D) ionic compound with respect to 100 parts by mass of the (A) acrylic polymer. 3 parts by mass or less.

7. The adhesive composition for an optical film according to any one of 1 to 6 above, wherein the microscopic latent value at 60 ° C may be 0.50 mm or less.

8. Another aspect of the present invention is an adhesive optical film, in which an adhesive layer containing the adhesive composition for an optical film according to any one of 1 to 7 is provided on one side or a double side of the optical film. surface.

9. The adhesive optical film according to 8 above, which may be an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptical polarizing film, an anti-reflection film, a brightness enhancement film, and a light diffusing film.

Since the adhesive composition for an optical film contains the component (B), the component (B) contains a group represented by the general formula (4) and / or a group represented by the general formula (5). The base makes the adhesive composition have a certain hardness, and imparts an appropriate cohesive force and elasticity to the adhesive composition. As a result, the adhesive composition can have a trade-off relationship Cohesion and elasticity. Therefore, the adhesive composition has a moderate adhesive force, exhibits excellent durability (humidity and heat resistance) under high temperature conditions or high temperature and humidity conditions, and is used to adhere to adherends such as liquid crystal cells and polarizing films. When using an optical film, light leakage can be reduced.

Furthermore, the above-mentioned adhesive optical film using the above-mentioned adhesive composition for an optical film is adhered to an adherend such as a liquid crystal cell with a moderate adhesive force, and exhibits excellent durability under high temperature conditions or under high temperature and humidity conditions, and When used to adhere to adherends such as liquid crystal cells, light leakage can be reduced.

100‧‧‧Image display device (LCD panel)

La, Lb, Lc, Ld‧ Brightness near the corner of the image display device

Lcenter‧‧‧ Brightness at the center of the image display device

FIG. 1 is a diagram schematically illustrating a method for measuring the brightness of an image display device (liquid crystal display panel, vertical alignment (VA) type) of an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a method for measuring the brightness of an image display device (liquid crystal display panel, twisted nematic (TN) type) of an embodiment of the present invention.

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

1. Adhesive composition for optical film

The adhesive composition for an optical film according to an embodiment of the present invention (hereinafter also simply referred to as "adhesive composition") contains an acrylic polymer (A) (hereinafter also simply referred to as "(A) component") Same as the following general formula (2) or The crosslinking agent (B) represented by the formula (3) (hereinafter also simply referred to as "(B) component").

(Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently an alkylene group containing 2 to 10 carbon atoms),

(Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently an alkylene group containing 2 to 10 carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F are independently alkylene groups containing 2 to 10 carbon atoms. Base),

(Where x is an integer from 2 to 10 and m is an integer from 1 to 10),

(In the formula, X represents a single bond or -O-, y is an integer of 2 to 10 and n is an integer of 1 to 10).

1.1. (A) Ingredient

The component (A) is an acrylic polymer derived from (a1) a (meth) acrylic acid ester monomer represented by the following general formula (1) and (a2) having an olefinic bis A monomer mixture of a bond with a monomer having at least one hydroxyl group.

(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having a carbon number of 1 to 14).

In the present invention, the "acrylic polymer" refers to a polymerization unit that contains at least one selected from acrylic acid, acrylate, acrylate, methacrylic acid, methacrylic acid salt, and methacrylic acid in a constituent unit of 50% by mass or more. Thing. In the present invention, the "olefinic double bond" means a carbon-carbon double bond (C = C). Therefore, the "monomer having one olefinic double bond in the molecule" means a monomer having a carbon-carbon double bond site.

In the general formula (1), the alkyl group having 1 to 14 carbon atoms represented by R _{2 is a} linear or branched alkyl group having 1 to 14 carbon atoms, and examples thereof include methyl and ethyl. Base, n-propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, n-pentyl, isopentyl, neopentyl, tertiary pentyl, 2-methylbutyl, 1-methyl Butylbutyl, n-hexyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, n- Nonyl, n-decyl, n-undecyl, n-dodecyl, n-decyl, n-tetradecyl (myristyl) and the like. Among them, R ₂ is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably a linear alkyl group having 1 to 10 carbon atoms.

In the present invention, the "aralkyl group" refers to an alkyl group in which one hydrogen atom of an alkyl group is substituted with an aryl group. Examples of the aralkyl group having 1 to 14 carbon atoms represented by R ₂ in the general formula (1) include benzyl (benzyl) and benzyl (phenethyl).

The content of the component (A) of the adhesive composition of the present embodiment may be 90 parts by mass relative to 100 parts by mass of the adhesive composition of the present embodiment. It is preferably 99.4 parts by mass or more and 95 parts by mass or more and 99.4 parts by mass or less.

The adhesive composition of this embodiment exhibits better adhesion and better durability, and can be used to more effectively reduce light leakage when used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film. From a viewpoint, it is preferable that (A) component is a polymer containing the monomer mixture of the following (a1) and (a2) monomer: (a1) (meth) acrylic acid ester monoester represented by the said general formula (1) (Hereinafter also simply referred to as "(a1) component") 90% by mass or more and 99.9% by mass or less (preferably 92% by mass or more and 98.9% by mass or less), (a2) has an olefinic double bond in the molecule and Monomer with at least one hydroxyl group (hereinafter also simply referred to as "(a2) component") 0.1 mass% to 10 mass% (preferably 0.6 mass% to 7 mass%, more preferably 0.6 mass% to 6 mass) %the following). In this case, the total amount of the component (a1) and the component (a2) is preferably 90.1% by mass or more and 100% by mass or less.

1.1.1. (A1) Ingredients

(a1) The component can improve the adhesion and durability of the adhesive composition of this embodiment. For (a1) the (meth) acrylate monomer represented by the above-mentioned general formula (1), for example, (a1-1) can be used assuming that the glass transition temperature (Tg) in the case of forming a homopolymer is 0 The (meth) acrylic acid ester monomer (hereinafter also simply referred to as "(a1-1) component") represented by the above-mentioned general formula (1) at a temperature higher than or equal to.

As the component (a1-1), the (meth) acrylic acid ester monomer represented by the above-mentioned general formula (1) where Tg is 0 ° C. or higher in the case of forming a homopolymer is exemplified by methyl acrylate Ester, methyl methacrylate, methyl Ethyl acrylate, n-propyl acrylate, n-propyl methacrylate, n-butyl methacrylate, n-hexadecyl acrylate, n-hexadecyl methacrylate, stearyl acrylate, stearyl methacrylate, etc. have Alkyl (meth) acrylates of linear alkyl groups; tertiary butyl acrylate, isopropyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, etc. (Meth) acrylic acid alkyl ester monomers; cyclohexyl acrylate, cyclohexyl methacrylate, isoamyl acrylate, isoamyl methacrylate, and dicyclopentyl acrylate are equivalent to the Group) acrylate monomers; (meth) acrylate monomers with aromatic ring groups such as benzyl methacrylate, benzyl acrylate, 2-naphthyl acrylate, etc., which can be used alone or in combination of two or more use. Among them, the point that the adhesive layer formed using the adhesive composition of this embodiment can further reduce light leakage of the image display device is that the component (a1-1) is assumed to be represented by the general formula (1) above. In the case of forming a homopolymer, the (meth) acrylic acid alkyl ester monomer having a Tg of 0 ° C or higher, and the alkyl chain constituting the (meth) acrylic acid alkyl ester monomer is linear or branched. Alkyl chains are preferred, and branched alkyl chains are more preferred. In this case, the point that the adhesive layer formed by using the adhesive composition of this embodiment can further reduce light leakage of the image display device is that the carbon number of the alkyl chain is more preferably 1 to 10 It is particularly preferable that it is 1 or more and 6 or less.

If the content of the component (a1-1) in the monomer mixture to obtain the polymer of the component (A) is less than 5% by mass, light leakage may not be sufficiently suppressed. On the other hand, if it exceeds 55% by mass %, There may be cases where the adhesive layer becomes too hard, the adhesion handling property becomes poor, and the durability is adversely affected. In order to sufficiently suppress light leakage and obtain adhesion with excellent durability The content of the component layer (a1-1) in the monomer mixture to obtain the polymer of the component (A) is preferably 5 mass% or more and 55 mass% or less, and 5 mass% or more and 40 mass% or less. Better.

Further, (a1) the (meth) acrylic acid ester monomer represented by the above-mentioned general formula (1), for example, (a1-2) can be used assuming that the glass transition temperature (Tg) does not reach 0 when a homopolymer is formed. The (meth) acrylic acid ester monomer (hereinafter also simply referred to as "(a1-2) component") represented by the above-mentioned general formula (1) at ° C.

As for the (a1-2) component, the (meth) acrylic acid ester represented by the above-mentioned general formula (1) where Tg does not reach 0 ° C. in the case of forming a homopolymer, for example, ethyl acrylate, N-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, lauryl methacrylate, acrylic acid (Meth) acrylic acid alkyl ester monomers having linear alkyl groups such as lauryl ester, n-tetradecyl methacrylate; isopropyl acrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate (Meth) acrylic acid alkyl ester monomers having branched alkyl groups, such as 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and phenoxyethyl acrylate, such as ( The alkyl (meth) acrylate monomers may be used alone or in combination of two or more thereof. Among them, the point that light leakage can be further reduced by using the adhesive layer formed by using the adhesive composition of this embodiment is that the (a1-2) component is assumed to have a Tg of less than 0 ° C in the case of forming a homopolymer. The (meth) acrylic acid alkyl ester monomer represented by the above general formula (1), and the alkyl chain constituting the (meth) acrylic acid alkyl ester is preferably a linear or branched alkyl chain. It is more preferable to have a linear alkyl chain. In this situation For the point that the adhesive layer formed by using the adhesive composition of this embodiment can further reduce light leakage of the image display device, the carbon number of the alkyl chain is preferably 1 or more and 10 or less.

If the content of the (a1-2) component in the aforementioned monomer mixture to obtain the polymer of the (A) component is less than 44.5 mass%, the adhesive physical properties will be lost, and the adhesion to the adherend will be insufficient. On the other hand, if it exceeds 94.5% by mass, light leakage may not be sufficiently suppressed. In order to obtain an adhesive layer that sufficiently suppresses light leakage and has excellent durability, the content of the component (a1-2) in the monomer mixture to obtain the polymer of component (A) is 44.5 mass% or more and 94.5 mass% or less. Preferably, it is more preferably 59.5 mass% or more and 90 mass% or less, and more preferably 69.5 mass% or more and 90 mass% or less.

(a1) The total amount of the component (a1-1) and the component (a1-2) is preferably 49.5 mass% or more and 100 mass% or less, and more preferably 64.5 mass% or more and 100 mass% or less.

1.1.2. (A2) Ingredient

By reacting the hydroxyl group contained in the component (a2) with the isocyanate group in the component (B), a crosslinked structure can be formed. (a2) Examples of the component include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and methacrylic acid. 4-hydroxybutyl acrylate, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-methacrylate A hydroxyl group-containing (meth) acrylate monomer such as 3-phenoxypropyl ester may be used singly or in combination of two or more thereof. Among them, especially with (Meth) acrylate monomers having a hydroxyl group of 1 to 6 are preferred.

1.1.3. (A3) Ingredient

The aforementioned monomer mixture to obtain the polymer of component (A) may further include (a3) a monomer having a reactive functional group other than at least one olefinic double bond and at least one hydroxyl group in the molecule (hereinafter also simply noted) "(A3) component"). In the present invention, the "reactive functional group" means a functional group capable of reacting with the component (B), and the reactive functional group contained in the component (a3) means, for example, at least one selected from the group consisting of a carboxyl group, an amine group, and amidine. And anhydride groups.

The reactive functional group contained in the component (a3) can be efficiently cross-linked by interacting with the isocyanate group in the component (B) to the hydroxyl group in the component (a2). (a3) Examples of the component include carboxyethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, and N, N-diethyl methacrylate Aminoethyl, acrylamide, N, N-dimethylaminopropylacrylamide, diacetone acrylamide, acrylmorpholine, acrylic acid, methacrylic acid, maleic acid, itaconic acid, Among them, one type may be used or two or more types may be used in combination. Among them, in terms of excellent efficiency in forming a crosslinked structure, the (a3) component is preferably at least one selected from the group consisting of acrylic acid and alkylphosphonium amine, and particularly preferably acrylic acid.

In order to obtain an adhesive layer that sufficiently suppresses light leakage and has excellent durability, the content of the component (a3) in the monomer mixture for obtaining the polymer of component (A) is preferably 0% by mass or more and 5% by mass or less. It is more preferably 0.1 mass% or more and 2 mass% or less.

In the adhesive composition of this embodiment, from the viewpoints of good adhesion and durability, and a reduction in light leakage can be more surely achieved. It can be seen that the total amount of the (a1) component, (a2) component, and (a3) in the monomer mixture to obtain the polymer of the component (A) may be 90.1% by mass to 100% by mass, and 95% by mass. More than 100% by mass is more preferable.

1.1.4. (A4) Ingredients

In addition, the aforementioned monomer mixture to obtain a polymer of the component (A) may further include a monomer (a4) other than the components (a1) to (a3), and is a monomer having one olefinic double bond in the molecule. (Hereinafter also simply referred to as "(a4) component"). Examples of the component (a4) include vinyl acetate, styrene, acrylonitrile, and macromonomers having a radical polymerizable vinyl group at a terminal of a monomer polymerized by a vinyl group. The content of the component (a4) in the monomer mixture to obtain the polymer of the component (A) is preferably 0% by mass or more and 2% by mass or less.

1.1.5. (A1) component, (a2) and (a3) and (a4) combined measurement

In the adhesive composition of this embodiment, from the standpoint of good adhesiveness and durability, and a more reliable reduction in light leakage, the above-mentioned monomer mixture in the above-mentioned monomer mixture for obtaining the polymer of the component (A) The total amount of (a1) component, (a2), (a3), and (a4) may be 90.1 mass% or more and 100 mass% or less, preferably 95 mass% or more and 100 mass% or less, and more preferably 100 mass% or less.

In addition, the adhesive composition of the present embodiment is preferably a content of a monomer having an epoxy alkyl group in terms of the point that light leakage can be further reduced by using the adhesive layer formed by the adhesive composition of the present embodiment. It is 5% by mass or less, and more preferably does not contain a monomer having an alkylene oxide group. Examples of the monomer having an alkylene oxide group include (meth) propyl groups having an alkylene oxide group in a side chain. An olefinic monomer, a reactive emulsifier with an alkylene oxide group. In the present invention, the "adhesive composition does not contain a monomer having an alkylene oxide group" means that the content of the monomer having an alkylene oxide group in the adhesive composition is 2% by mass or less. In particular, the content of the monomer having an alkylene oxide group in the adhesive composition is preferably 0% by mass or more and 2% by mass or less.

1.1.6.Tg

In the adhesive composition of this embodiment, from the viewpoints of good adhesion and durability, and a more reliable reduction in light leakage, the Tg of the component (A) is preferably -70 ° C or higher and 0 ° C or lower. Above -60 ° C and below -10 ° C is more preferred. In the present invention, the Tg of the component (A) is a value calculated from the following formula (6) (formula of FOX).

1 / Tg _A = W _a1 / Tg _a1 + W _a2 / Tg _a2 + W _a3 / Tg _a3 + W _a4 / Tg _a4 ‧‧‧‧ (6)

(In the formula, Tg _A represents the glass transition temperature (K) of the (A) component, and Tg _a1 , Tg _a2 , Tg _a3 , and Tg _a4 represent the constituent monomers (a1), (a2), (a3), and (a4), respectively. ) The glass transition temperature (Tg (K)) of the homopolymer prepared, W _a1 , W _a2 , W _a3 , and W _a4 respectively represent the constituent monomers (a1), (a2), and (a) contained in the component (A). (a3), (a4) weight fraction).

In addition, since TgA calculated by the above formula (6) is an absolute temperature (K), it can be converted into a Celsius temperature (° C) as necessary.

The glass transition temperature of a homopolymer prepared from a representative monomer is shown in Table 1 below. More specifically, it is described in, for example, the Polymer Handbook Fourth Edition, Wiley-Interscience, 1999. )Wait.

1.1.7. Weight average molecular weight (Mw)

Furthermore, in the adhesive composition of this embodiment, from the viewpoints of good adhesion and durability, and a more reliable reduction in light leakage, the component A) preferably has a weight average molecular weight (Mw) of 500,000 or more Over 2 million It is more preferably 800,000 to 1.8 million. The weight-average molecular weight of the component (A) is obtained by using GPC (colloidal permeation chromatography) and calculating the weight-average molecular weight (Mw) of standard polystyrene under the following conditions.

<GPC measurement conditions>

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

GPC pipe string composition: The following 5 connected pipe strings (all manufactured by Tosoh Corporation)

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

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: diluted with tetrahydrofuran to 1.0 mg / cm ³

Mobile phase solvent: tetrahydrofuran

Flow: 1.0cm ³ / min

Column temperature: 40 ℃

The component (A) in this embodiment is preferably one in which the molecular weight distribution (weight average molecular weight / number average molecular weight) obtained by GPC described above is in a range of 4 or more and 7 or less. In the component (A), the aforementioned molecular weight distribution is 7 or less, which means that the proportion of the high molecular weight component is high and the proportion of the low molecular weight component is less. Therefore, the adhesive layer obtained by using the component (A) can be maintained under the durability test conditions. The cohesive force of the adhesive layer can further improve the durability of the adhesive layer, which is preferable in this regard. In addition, since the molecular weight distribution of the component (A) is 4 or more, the component (A) becomes a polymer having a molecular weight distribution to a certain degree. Therefore, adhesion to the component (A) can be achieved. The agent composition imparts moderate stress relaxation.

1.2. (B) ingredients

As described above, in the adhesive composition of the present embodiment, the crosslinking agent of the component (B) includes a crosslinking agent represented by the general formula (2) or the general formula (3).

In the adhesive composition of this embodiment, from the viewpoint of providing more excellent adhesion and durability, and more reliably preventing light leakage, the general formula (2) or the general formula (3) contains ^Among the groups represented by the general formula (4) of R ^1A , R ^1B , and R ^1C , x is preferably an integer of 2 to 10 (more preferably, an integer of 4 to 8), and m is 1 to 10. The integers below are more preferred (the integers from 1 to 6 are most preferred). In addition, in the group represented by the general formula (5) of R ^1A , R ^1B , and R ^1C contained in the general formula (2) or the general formula (3), it is preferable that y is an integer of 2 or more and 10 or less. It is more preferable to use an integer of 4 to 8, n is an integer of 1 to 10, and an integer of 1 to 6 is more preferable. In addition, R ^1A , R ^1B , and R ^1C may be the same or different, or a combination of plural numbers.

In the general formula (2) or the general formula (3), the alkylene group contained in R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , R ^3F may be, for example, It is linear, branched, or cyclic, and is preferably linear. Examples of the alkylene group include methylene, ethylene, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, and cyclohexanedimethylene. The carbon number of this alkylene group is preferably 2 or more and 10 or less, and more preferably 4 or more and 8 or less. Moreover, R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F may each be an alkylene group. R ^2A , R ^2B , and R ^2C may be the same or different. Moreover, R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F may be the same or different.

The component (B) is an isocyanate-based crosslinking agent. More specifically, the component (B) has a skeleton derived from trimethylolpropane (-) as shown in the general formula (2) or the general formula (3). (O-CH _2- ) ₃ -C-CH ₂ CH ₃ ), and an isocyanate (-N = C = O) group.

From the viewpoint that a moderate elasticity can be imparted to the adhesive composition of this embodiment, the component (B) may have, for example, a degree of crosslinking (the number of isocyanate groups contained in the (B) component of one molecule) is 1 or more and 9 Hereinafter, the degree of crosslinking is preferably 3 or more and 6 or less. The component (B) can be obtained, for example, by condensing an acid halide (or an ester or a carboxylic acid) having trimethylolpropane and an isocyanate group.

In the adhesive composition of the present embodiment, from the viewpoint of achieving a balance between cohesion and elasticity, the molecular weight of the component (B) is preferably 500 or more and 10,000 or less, and more preferably 2,000 or more and 7,000 or less.

Since the adhesive composition of the present embodiment contains the component (B), the component (B) contains a group represented by the general formula (4) and / or a group represented by the general formula (5). The adhesive composition imparts moderate cohesion and elasticity. As a result, the adhesive composition can have both cohesive force and elasticity, which are mostly mutually compensated. Therefore, when the adhesive composition is used to form an adhesive layer of an image display device using the adhesive composition, it is possible to prevent light leakage and improve adhesion and durability (damp heat resistance).

In general, when the adhesive composition is too hard (when the adhesive composition has high cohesive force and low elasticity), the adhesive layer formed by using the adhesive composition may crack; on the other hand, the adhesive composition When the substance is too soft (when the adhesive composition has low cohesive force and high elasticity), the adhesive layer formed by using the adhesive composition may have air bubbles entering, and may Poor appearance. In contrast, by including the component (B) in the adhesive composition of this embodiment, the adhesive composition has moderate cohesion and elasticity, so it can prevent cracking of the adhesive layer and prevent bubbles from entering the adhesive. Floor.

The content of the (B) component of the adhesive composition of the present embodiment may be 0.05 from 100 parts by mass of the (A) component of the present embodiment from the viewpoint of preventing light leakage and improving adhesion and durability. At least 5 parts by mass and preferably at least 4 parts by mass.

As the component (B), a commercially available crosslinking agent can be used. For example, (B) component can be used: D-94 (seller: Iken Chemical Co., Ltd.), E405-70B (seller: Asahi Kasei Corporation), MFA-75B (seller: Asahi Kasei Corporation), and the like.

The adhesive composition for an optical film according to this embodiment may be less than the general formula (2) or (B) by including the cross-linking agent represented by the general formula (2) or the general formula (3). A cross-linking agent having a structure represented by the above-mentioned general formula (3) (for example, a commercially available isocyanate-based cross-linking agent, NY 730A (seller: Mitsubishi Chemical Corporation), L-45 (seller: Comprehensive Research Chemical Co., Ltd. ), CORONATE HL (seller: Nippon Polyurethane Co., Ltd.) and the like) more reliably reduce light leakage and have excellent durability (humidity and heat resistance).

1.3. Other ingredients

The adhesive composition for optical films of this embodiment may further contain components other than (A) component and (B) component as needed. For example, without compromising Within the range of the effects of the present invention, (C) a silane coupling agent (hereinafter also simply referred to as "(C) component"), (D) an ionic compound (hereinafter also simply referred to in the adhesive composition of this embodiment) "(D) component"), antioxidant, ultraviolet absorber, tackifier, plasticizer, etc.

1.3.1. (C) Silane coupling agent

The adhesive composition for an optical film according to this embodiment contains the component (C), and when the adhesive composition for an optical film according to this embodiment is used to form an adhesive layer on the surface of an adherend, the adhesive layer can be well maintained. Followed by the adherend. The component (C) may be, for example, a polymerizable unsaturated group-containing silicon compound such as ethylene trimethoxysilane, ethylene triethoxysilane, and methacryloxypropyltrimethoxysilane; 3-glycidoxy Ethylpropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane have epoxy structures Silicon compounds; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-amine Silyl compounds containing amine groups such as propylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; oligomer-type silane coupling agents, etc., where peeling does not easily occur in hot and humid environments In particular, a silane coupling agent having a functional group that reacts with a functional group contained in the (meth) acrylic copolymer (A) is preferred.

The content of the component (C) in the adhesive composition for an optical film according to this embodiment is 0.01 parts by mass relative to 100 parts by mass of the component (A) from the viewpoint of being able to be well maintained and adhered to the adherend. The above is 0.5 parts by mass or less, preferably 0.05 to 0.3 parts by mass.

1.3.2. (D) Ionic compounds

Moreover, the adhesive composition of this embodiment may contain an ionic compound (D). By including the component (D) in the adhesive composition of this embodiment, when the adhesive composition of this embodiment is used to form an adhesive layer on the surface of an adherend, it can effectively prevent the adherend from being charged. Examples of the component (D) include ionic compounds which are liquid or solid at 25 ° C including anions and cations, and specifically, alkali metal salts and ionic liquids (liquid at 25 ° C) , Surfactants and so on.

Examples of the alkali metal salt include compounds containing alkali metal cations and anions such as lithium, sodium, and potassium. Specific examples include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, potassium chlorate, and potassium nitrate. , Sodium nitrate, sodium carbonate, sodium thiocyanate, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, sodium acetate, sodium alginate, sodium lignosulfonate, sodium toluenesulfonate, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) IN, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) IN, Li (CF ₃ SO ₂ ) ₃ C, and the like.

Examples of the cations constituting the ionic liquid include piperidinium cations, pyrrolidium cations, cations with pyrroline skeleton, cations with pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, cation pyrazole, pyrazoline cation, tetraalkylammonium cation, a trialkyl sulfonium cation, a tetraalkylphosphonium cation and the like; anion constituting the ionic liquids 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 to 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.

Next, examples of the ionic compound include ionic compounds composed of the cations and the anions which are liquid at 25 ° C. Specific examples of such an ionic compound include 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, and 1,2-dimethylformaldehyde. Indole tetrafluoroborate, 1-ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1 -Ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium dicyanimide, 1-ethyl-3-methylimidazolium bis (trifluoromethyl) Sulfofluorenyl) imine, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imine, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) Methyl compound, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetic acid Salt, 1-butyl-3-methylimidazolium heptafluorobutyrate, 1-butyl-3-methylimidazolium triflate, 1-butyl-3-methylimidazolium perfluoro Butanesulfonate, 1-butyl-3-methylimidazolium bis (tri Methanesulfonyl) imine, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1 -Hexyl-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-dimethyl-3-propylimidazolium bis (trifluoromethyl) Sulfonyl) imine, 1-methylpyrazolium tetrafluoroborate, 3-methylpyrazolium tetrafluoroborate, tetrahexylammonium bis (trifluoromethanesulfonyl) imine, diallyl Dimethylammonium tetrafluoroborate, diallyldimethyl Ammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imine, diallyldimethylammonium bis (pentafluoroethanesulfonyl) imine, N , N-Diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2-methoxy (Ethyl) ammonium trifluoromethanesulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imine, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imine, epoxypropyltrimethylammonium trifluoromethanesulfonate, Glycidyl trimethylammonium bis (trifluoromethanesulfonyl) imine, glycidyl trimethylammonium bis (pentafluoroethanesulfonyl) imine, 1-butylpyridinium (trifluoromethyl Sulfonyl) trifluoroacetamidamine, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamidamine, 1-ethyl-3-methylimidazolium (trifluoromethyl) Sulfonyl) trifluoroacetamidamine, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium (trifluoromethanesulfonyl) trifluoroacetamidamine, diamine Allyldimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, epoxypropyltrimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-dimethyl -N-B -N-propylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethyl) Sulfo) imine, N, N-dimethyl-N-ethyl-N-heptylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-ethyl- N-nonylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) imine, N, N-di Methyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) ) Imine, N, N-dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) amine, N, N-dimethyl-N-propyl-N-heptyl Ammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-butyl -N-hexylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl) imine, N, N -Dimethyl-N-pentyl-N-hexylammonium bis (trifluoromethanesulfonyl) imine, N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) Imine, trimethylheptylammonium bis (trifluoromethanesulfonyl) imine, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imine N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imine, N, N-diethyl-N-methyl-N-heptylammonium bis (Trifluoromethanesulfonyl) imine, N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imine, triethylpropylammonium bis (tri Flumethanesulfonyl) imine, triethylpentylammonium bis (trifluoromethanesulfonyl) imine, triethylheptylammonium bis (trifluoromethanesulfonyl) imine, N, N-di Propyl-N-methyl-N-ethylammonium bis (trifluoromethanesulfonyl) imine, N, N-dipropyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) ) Imine, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imine, N, N-dipropyl-N, N-dihexylammonium bis (Trifluoromethanesulfonyl) imine, N, N-dibutyl-N-methyl-N-pentylammonium bis ( Trifluoromethanesulfonyl) imine, N, N-dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imine, trioctylmethylammonium bis (trifluoromethyl) Sulfofluorenyl) imine, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imine and the like.

The surfactant may be any of a nonionic surfactant, a cationic surfactant, an anionic surfactant, and an amphoteric surfactant.

Examples of the non-ionic surfactant include polyvinyl alkyl ethers such as polyethylene lauryl ether and polyethylene stearyl ether; and polyvinyl alkyl ethers such as polyethylene octylphenyl ether and polyethylene nonylphenyl ether. Phenyl ethers Higher fatty acid esters of sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, etc .; higher fatty acid esters of polyethylene sorbitan monolaurate, etc. ; Polyethylene higher fatty acid esters such as polyethylene monolaurate, polyethylene monostearate; for example, glycerol higher fatty acid esters such as oleic acid monoglyceride, stearic acid monoglyceride; polyethylene, polypropylene, polybutylene Polyoxyolefins such as olefins and block copolymers of these.

Examples of the cationic surfactant include alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzylammonium chloride, and alkyldimethylammonium ethyl sulfate.

Examples of the anionic surfactant include carboxylates such as sodium laurate, sodium oleate, N-fluorenyl-N-methylglycine sodium salt, and sodium polyethylene lauryl ether carboxylate; dodecylbenzene Sulfonates such as sodium sulfonate, dialkyl sulfosuccinate, sodium dimethyl-5-sulfoisophthalate; sodium lauryl sulfate, polyethylene lauryl ether sodium sulfate, polyvinyl nonylphenyl Sulfate salts such as sodium ether sulfate; phosphate salts such as polyethylene sodium lauryl phosphate and polyethylene nonylphenyl ether sodium phosphate.

Examples of the amphoteric surfactant include a carboxybetaine-type surfactant, an aminocarboxylate, imidazolinium betaine, lecithin, and an alkylamine oxide. In addition, conductive polymers, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, and the like can be used for other systems.

Among them, organic salts which are liquid at 25 ° C are particularly suitable.

The content of the component (D) in the adhesive composition for an optical film of the present embodiment may be 0.01 parts by mass or more and 3 parts by mass or less, based on 100 parts by mass of the component (A) of the present embodiment, and 0.05 parts by mass or more and 2.5 It is preferably less than or equal to part by mass.

1.4. (A) Component polymerization method

(A) The polymerization method of the component is not particularly limited, and polymerization can be performed by a known method such as solution polymerization, emulsion polymerization, suspension polymerization, etc., but the adhesive composition of the present invention is produced by using a mixture of copolymers obtained by polymerization In this case, from the viewpoint that the processing steps are simple and can be performed in a short time, it is preferable to perform polymerization by solution polymerization.

Generally, solution polymerization is carried out in a polymerization tank with a specific organic solvent, each monomer, a polymerization initiator, and a chain transfer agent, if necessary, and the like, while stirring under a nitrogen stream or the reflux temperature of the organic solvent. It heats and reacts for several hours.

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 benzene, toluene, ethylbenzene, n-propylbenzene, tertiary butylbenzene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, decahydronaphthalene, and aromatic Aromatic hydrocarbons such as naphtha; for example: n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirit, petroleum brain naphtha), turpentine oil and other aliphatic or alicyclic hydrocarbons; for example: ethyl acetate, n-butyl acetate, n-pentyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate , 3-methoxybutyl acetate, methyl benzoate and other esters; for example: acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl cyclohexanone and other ketones ; For example: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethyl ether Glycol ethers such as glycol monobutyl ether; for example: alcohols such as methyl alcohol, ethyl alcohol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, tertiary butanol ;Wait. These organic solvents can be used individually or in mixture of 2 or more types.

Among the organic solvents for polymerization, when the component (A) is polymerized, an organic solvent that is not likely to undergo chain transfer during the polymerization reaction is used. For example, esters and ketones are preferably used. In particular, the component (A) In terms of solubility, ease of polymerization reaction, and the like, it is more preferable to use ethyl acetate, methyl ethyl ketone, acetone, and the like.

As the polymerization initiator, organic peroxides, azo compounds, and the like that are generally used for solution polymerization can be used. Examples of such organic peroxides include tertiary butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzamyl peroxide, and lauryl hydrazone. Peroxide, hexamethylene peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, tert-butyl peroxyisobutyrate, 2,2-bis ( 4,4-di-tertiary-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-tertiary-pentylperoxycyclohexyl) propane, 2,2-bis (4,4- Di-tertiary octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-isophenylpropylperoxycyclohexyl) propane, 2,2-bis (4,4-di- Tertiary butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-tertiary octylperoxycyclohexyl) butane, etc .; azo compounds, for example, 2,2'- Azobis-isobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylpentane Nitrile and so on.

Among these polymerization initiators, a polymerization initiator that does not undergo a graft reaction during the polymerization reaction of the component (A) is preferred, and an azo-based polymerization initiator is particularly preferred. Polymerization initiator. The amount used is generally 0.01 to 2 parts by mass, and preferably 0.1 to 1.0 parts by mass with respect to 100 parts by mass of the total monomer.

In addition, when producing the (A) component contained in the adhesive composition of the present invention, a chain transfer agent is generally not used, but may be used within a range that does not impair the object and effect of the present invention as necessary.

Examples of such chain transfer agents include: cyanoacetic acid; alkyl esters of cyanoacetic acid having a carbon number of 1 to 8; bromoacetic acid; alkyl esters of bromoacetic acid having a carbon number of 1 to 8; , Hydrazone, 9-phenylhydrazone and other aromatic compounds; p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene and other aromatic compounds Nitro compounds; benzoquinone derivatives such as benzoquinone, 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, tetrachloride Halogenated hydrocarbons such as carbon, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-propene; chloral, furfural (furaldehyde) and other aldehydes: alkyl mercaptans with 1 to 18 carbons; aromatic thiols such as thiophenol and toluene mercaptan; alkyls with 1 to 10 carbons in thioacetic acid and thioacetic acid Esters; hydroxyalkyl mercaptans with carbon number of 1 to 12; terpenes such as pinene and terpinolene; etc.

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

1.5. Micro-creep value

Moreover, the adhesive composition of this embodiment has a microscopic latent change at 60 ° C from the viewpoint of more reliably preventing light leakage and further improving adhesion and durability. The value is preferably 0.50 mm or less when a load of 800 g is applied for 1000 seconds, and more preferably 0.35 mm or less. In the present invention, the microscopic latent value can be measured using the method described in the examples.

As a result of the adhesive composition of this embodiment, the shrinkage of the adhesive layer formed by the adhesive composition is suppressed, and the shrinkage of the optical film provided in the adhesive layer can be suppressed to more surely prevent light leakage. From a viewpoint, the difference between the microscopic latent value at 60 ° C and the microscopic latent value at 23 ° C is better, for example, based on the microscopic latent value at 60 ° C and the difference between 23 ° C The microscopic latent value is better than 0.30mm.

1.6. Manufacture of adhesive composition

The adhesive composition according to this embodiment is generally prepared by mixing the aforementioned components (A) and (B) and any desired components simultaneously or in any order. In addition, when the component (A) and the component (B) are mixed, when the component (A) is prepared by solution polymerization, the component (B) may be added to the solution containing the component (A) after the polymerization is completed. In the case where the (A) component is prepared by block polymerization, it is difficult to uniformly mix after the polymerization is completed. Therefore, it is preferable to add the (B) component during the polymerization and mix.

1.7. Uses and effects

The adhesive composition of this embodiment can be suitably used as an adhesive of an optical film (detailed later). According to the adhesive composition of this embodiment, It exhibits excellent durability under high temperature and humidity conditions, and can reduce light leakage when it is used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film. When the image display device includes a retardation film, a retardation film can be provided between the liquid crystal cell and the polarizing film. Therefore, an adhesive using the adhesive composition of this embodiment can be provided between the retardation film and the polarizing film.剂 层。 The agent layer.

For example, when the adhesive composition of this embodiment is used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film, it can achieve good light leakage prevention characteristics and high durability, so it can achieve high image quality of an image display device. Qualitative. In this case, the adhesive composition of this embodiment can be used as an adhesive for an adherend using a polarizing film for a VA mode, a polarizing film for a TN mode, or a polarizing film for an IPS mode, thereby achieving high image quality. From the point of view, it can be suitably used as an adhesive for a VA mode polarizing film or a TN mode polarizing film as an adherend.

It is estimated that the light leakage prevention property, which is one of the effects of the adhesive composition of this embodiment, is formed by the following action mechanism.

That is, when an adhesive layer is provided on the surface of an optical film (polarizing film) using the adhesive composition of this embodiment, the adhesive composition has the component (B) because the component (B) contains Containing a group represented by the general formula (4) and / or a group represented by the general formula (5) to make the adhesive composition have a certain hardness, and to impart a moderate cohesive force to the adhesive composition And flexibility. As a result, the adhesive composition can have both cohesive force and elasticity, which are mostly mutually compensated. Therefore, when an adhesive layer of an image display device is formed using the adhesive composition, light leakage can be prevented, and adhesion and durability (damp heat resistance) can be improved.

2. Adhesive Optical Film

In the adhesive optical film according to another embodiment of the present invention, an adhesive layer containing the adhesive composition for an optical film of the above embodiment is provided on one side or both sides of the optical film. When producing the adhesive optical film of this embodiment, the adhesive layer may be a method in which the adhesive composition is passed through a gravure coater, a Meyer bar coater, an air knife coater, or a roller. A coating machine or the like is coated on the optical film, and the adhesive composition coated on the optical film is formed by drying and crosslinking at normal temperature or heating, or an adhesive layer may be provided on the release film, and This adhesive layer was formed by transferring to the optical film. The thickness of the adhesive layer is generally 1 μm to 50 μm, and preferably 5 μm to 30 μm. In addition, before using the adhesive optical film, the film may be peeled off from the surface area layer of the adhesive layer to protect the adhesive layer.

In addition, the adhesive optical film of the present embodiment may be used by an image display device such as an FPD. For example, it may be an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptical polarizing film, an anti-reflection film, a brightness enhancement film, and a light diffusion film. The thickness of the optical film is appropriately selected depending on the purpose of use, and is generally 10 μm to 500 μm, and preferably 15 μm to 300 μm.

(Example)

3. Examples

The present invention is described below with reference to the following examples, but the present invention is not limited to the examples.

3.1. (A) Modulation of component

A reaction device having a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube was charged with a monomer mixture having a blending ratio shown in Table 2 below, and then ethyl acetate was charged so that the blended amount became the monomer concentration. 50% by mass. Next, 0.1 part by mass of azobisisobutyronitrile was added, and the air in the reaction vessel was replaced with nitrogen gas, stirred and heated to 60 ° C., and then allowed to react for 8 hours. After completion of the reaction, it was diluted with ethyl acetate to obtain the component (A) (acrylic polymers A to G).

3.2. Production of Adhesive Processing Polarizers for Evaluation

Using the component (A) obtained in the above 3.1. And adding each component in accordance with the formulation (solid content formulation) in Tables 3 and 4 below, solutions of the adhesive composition of Examples 1 to 15 and Comparative Examples 1 to 11 were obtained . By applying the solution of the adhesive composition to the surface of the peeled polyester film and drying it, an adhesive sheet having an adhesive layer having a thickness of 20 μm was obtained. This adhesive sheet was adhered to one side of a polarizing film for VA mode, and then matured in a dark place at 23 ° C./50% RH for 7 days to obtain an adhesive-processed polarizing plate for evaluation. The component (B) is as shown in Tables 3 and 4 below, and the crosslinking agents 1 to 6 were used. The cross-linking agents 1 to 6 have structures represented by the following structural formulae (7) to (12), respectively. The weight average molecular weight (MW) of the crosslinking agent 1 was about 3,700, the weight average molecular weight (MW) of the crosslinking agent 2 was about 4,000, and the weight average molecular weight (MW) of the crosslinking agent 3 was about 4,000.

[Crosslinking agent 1]

(In the formula, l is 1 or more and 10 or less, m is 1 or more and 10 or less, n is 1 or more and 10 or less, a is 1 or more and 10 or less, b is 1 or more and 10 or less, and c is 1 or more and 10 or less).

[Crosslinking Agent 2]

(Where l is 1 or more and 10 or less, m is 1 or more and 10 or less, n (From 1 to 10).

[Crosslinking Agent 3]

(In the formula, l is 1 or more and 10 or less, m is 1 or more and 10 or less, and n is 1 or more and 10 or less).

[Crosslinking agent 4]

[Crosslinking agent 5]

[Crosslinking agent 6]

For each evaluation-adhesive-processed polarizing plate, use the following method Method to evaluate the maximum deformation rate, strain recovery rate, light leakage (light source using LED: LED method), light leakage (light source without LED: non-LED method), humidity and heat resistance (foaming) And breaks).

3.3. Evaluation methods

3.3.1. Light leakage

A method of attaching an evaluation-adhesive polarizing plate for which a peeled polyester film has been peeled off to the aforementioned liquid crystal panel with an adhesive layer, and a method for converting the above-mentioned evaluation-adhesive polarizing plate into crossed nicols, 19-inch VA type LCD panel (manufactured by IO Data Corporation, type: taken out by LCD-A191EW), placed at 80 ° C for 240 hours, and then placed at 23 ° C / 50% RH 2 hours. After that, the liquid crystal panel to which the aforementioned polarizing plate is attached is connected to a computer in a dark room, and a completely black screen is displayed. In this test, two types of panels, a VA-type liquid crystal panel and a TN-type liquid crystal panel, were used as the liquid crystal panel for evaluation. For a display screen displaying a completely black screen, a brightness meter (manufactured by HI-LAND, model: RISA-COLOR / CD8) was used to measure the brightness (La, Lb) of a 1 cm diameter area near each corner as shown in FIG. , Lc, Ld) and the brightness (Lcenter) of a 1 cm diameter area in the center of the screen, and the light leakage (ΔL) was calculated according to the following formula (13). The smaller ΔL means less light leakage (from the backlight). Generally, as long as ΔL is not more than 2.0, it can be used as a liquid crystal display panel.

△ L = (La + Lb + Lc + Ld) / 4-Lcenter‧‧‧ (13)

Further, for a VA-type liquid crystal panel, the range (R) where light leakage occurs near the corner of the display screen as shown by the dotted line in FIG. 1 is visually measured, and for the TN-type liquid crystal panel, visual inspection is performed. The range (R) where light leakage occurs near the periphery of the display screen as shown by the dotted line in FIG. 2 is determined. The smaller the range in which light leakage occurs, the less the light leakage. In general, as long as R is less than 20 mm, it can be used as a liquid crystal display panel. Still more preferably, it is less than 16.5 mm.

3.3.2. Microvision latent value

Each evaluation-adhesive-processed polarizing plate was cut into a width of 10 mm × length 100 mm, and each evaluation-adhesive-processed polarizing plate with the peeled polyester film was contacted with an adhesive layer and glass, and the bonding area became 100mm ² (10mm × 10mm) bonding, autoclave treatment (50 ° C, 5atm), and then left to stand in a 23 ° C / 50% RH environment for 24 hours. The obtained sample was used as a sample for a microscopic creep test. The test specimen was placed in a test fixture with a length of 15 mm in a test chamber of a micro-vision latent measuring machine (manufactured by Hidehiro Seiki Co., Ltd., model name: TA.TX.PLUS). When the test data was fixed up and down and 800 g of load was applied in the vertical direction for 1000 seconds, the offset distance between the adhesion end of the sample and the adherend compared to the original was measured.

3.3.3. Humidity and heat resistance

The adhesive-processed polarizing plate for evaluation of the peeled polyester film was cut to 15 inches (233 mm x 309 mm), and was laminated to a thickness of 0.5 mm using a laminating roller so that the adhesive layer was in contact with the aforementioned glass plate. Single side of alkali glass plate. After sticking, it was subjected to a pressure treatment in an autoclave (manufactured by Kurihara Seisakusho) under conditions of 0.5 MPa, 50 ° C, and 20 minutes to obtain a test plate. The test plate obtained in this way was left to stand at 60 ° C / 90% RH for 500 hours. After the test, remove the test plate from the test environment, and leave it to stand for 2 hours at 23 ° C / 50% RH, and then visually observe the foaming of the adhesive layer (lack of cohesion), It was broken (excessively crosslinked), and the moist heat resistance was evaluated by the following evaluation criteria.

(Bubbly-size)

○: No foaming was seen at all

△: Foaming diameter is below 1mm

×: Bubble diameter is larger than 1mm

(Foaming-production amount)

○: No foaming was seen at all

△: The number of bubbles is less than 10

×: The number of blistering is more than 10

(Break-size)

○: No fracture was seen at all

△: The area where fracture occurred was less than 5% with respect to the entire bonding portion (100%) of the test plate

×: The area where fracture occurred was 5% or more with respect to the entire bonding portion (100%) of the test plate.

(Break-position)

○: No break at all

△: Defect only in a 1 cm width area near each end of the test plate

×: There is a defect in the 1 cm width area near each end of the test plate and outside the area

The abbreviations in Table 2 have the following meanings.

AA: Acrylic

BA: n-butyl acrylate

t-BA: tert-butyl acrylate

4-HBA: 4-hydroxybutyl acrylate

HEA: 2-hydroxyethyl acrylate

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

MA: methyl acrylate

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

Ionic compound ((D) component: antistatic agent): 1-octyl-4-methylpyridinium-bis (fluorosulfonyl) imine

From the results of Tables 3 and 4, it can be seen that the compositions of Examples 1 to 15 above include the cross-linking agents 1 to 3 represented by the general formula (2) or the general formula (3) as the component (B). , While achieving high adhesion and excellent durability, and can reduce light leakage. In contrast, the compositions of Comparative Examples 1 to 11 do not contain the crosslinking agent represented by the general formula (2) or the general formula (3) as the component (B) (the crosslinking agents 4 to 6 used Has the structure represented by the general formula (2) or the general formula (3)) (Comparative Examples 1 to 11), and the reduction of light leakage cannot be sufficiently achieved.

(Industrial availability)

Claims (7)

An adhesive composition for an optical film, comprising: (A) an acrylic polymer including (a1) a (meth) acrylate monomer represented by the following general formula (1) and (a2) a molecule A polymer of a monomer mixture having a monomer having one olefinic double bond and at least one hydroxyl group therein, wherein the monomer mixture includes the (meth) acrylic acid represented by the aforementioned general formula (1) (a1) The ester monomer is 90% by mass or more and 99.9% by mass or less, and the above (a2) monomer having one olefinic double bond and at least one hydroxyl group in the molecule is 0.1% by mass or more and 10% by mass or less, constituting the unit of (a1) The body composition contains a monomer (a1-1) which is assumed to have a glass transition temperature (Tg) of 0 ° C or higher in the case of forming a homopolymer, and the monomer (a1-1) is an alkyl (meth) acrylate monoester And a molecular weight distribution of 4 or more and 7 or less; (B) a crosslinking agent represented by the following general formula (2) or the following general formula (3), which contains 100 masses of the acrylic polymer (A) Parts of the aforementioned (B) crosslinking agent is 0.05 parts by mass or more and 5 parts by mass or less; (Wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having a carbon number of 1 to 14), (Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently a group containing an alkylene group having 2 to 10 carbon atoms), (Wherein R ^1A , R ^1B , and R ^1C are each independently a group containing a group represented by the following general formula (4) and / or a group represented by the following general formula (5), and R ^2A , R ^2B , R ^2C is independently an alkylene group containing 2 to 10 carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F are independently alkylene groups containing 2 to 10 carbon atoms. Base), (Where x is an integer from 2 to 10 and m is an integer from 1 to 10), (In the formula, X represents a single bond or -O-, y is an integer of 2 to 10 and n is an integer of 1 to 10). The adhesive composition for an optical film according to item 1 of the scope of the patent application, wherein the monomer mixture includes the (meth) acrylate monomers shown in (a1-1) and (a1-2) as the ( a1) The (meth) acrylic acid ester monomer represented by the above general formula (1): (a1-1) Assuming that the glass transition temperature (Tg) in the case of forming a homopolymer is 0 ° C or higher, the above general formula ( 1) The (meth) acrylic acid alkyl ester monomer shown is 5 mass% or more and 55 mass% or less; (a1-2) It is assumed that the glass transition temperature (Tg) in the case of forming a homopolymer is less than 0 ° C. The (meth) acrylate monomer represented by the general formula (1) is 44.5 mass% or more and 94.5 mass% or less. Among them, the total amount of the (a1) and the (a2) is 90.1 mass% or more and 100 mass% or less. . The adhesive composition for an optical film according to item 1 or item 2 of the patent application scope, further comprising (C) from 0.01 to 0.5 parts by mass based on 100 parts by mass of the acrylic polymer (A). ) Silane coupling agent. The adhesive composition for an optical film according to item 1 or item 2 of the patent application scope, further comprising 0.01 to 3 parts by mass of (D) with respect to 100 parts by mass of the acrylic polymer (A). ) Ionic compounds. The adhesive composition for an optical film according to item 1 or item 2 of the patent application scope, wherein the microscopic latent value at 60 ° C is 0.50 mm or less. An adhesive optical film is provided with an adhesive layer containing the adhesive composition for an optical film according to any one of the scope of claims 1 to 5 of the application for a patent, and is provided on one or both sides of the optical film. The adhesive optical film according to item 6 of the patent application scope, which is an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptical polarizing film, an anti-reflection film, a brightness enhancement film, and a light diffusion film.