TW201446907A - Adhesive composition for optical film and adhesive type optical film - Google Patents

Abstract

This present invention provides an adhesive composition for optical film, the composition containing: (A) an acrylic polymer which is a polymer of a mixture of monomers including (a1) a (meth) acrylic acid ester monomer having a specific construction, and (a2) a monomer having one olefinic double bond and at least one hydroxyl group in the molecule, and (B) a crosslinking agent having a specific construction.

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 under various uses and conditions, for example, not only at room temperature, but also at high temperatures, even under severe conditions called so-called high temperature and humidity. The use in high-temperature or high-temperature humid conditions may be, for example, use in a tropical area, inside a vehicle, or in an interior of an outdoor measuring machine.

Further, an optical film such as a polarizing film constituting the image display device is produced by adsorbing a dye having a dichroic property to a polymer film such as polyvinyl alcohol, and extending and orienting the film. Therefore, the optical film shrinks under high temperature and humidity conditions, and dimensional deformation occurs. Moreover, once the optical film is dimensionally deformed, it is difficult to completely return to the original size even if the temperature condition and the humidity condition are changed, for example. As a result, the optical film may be cracked, peeled, and floated due to the influence of the stress caused by the dimensional change, and light leakage due to deformation of the polarization axis may occur in the image display device.

Further, in recent years, large screens, high image quality, and high durability of image display devices have been demanded. In order to solve the appearance defects such as light leakage due to dimensional change of an optical film such as a polarizing film, peeling in a high-temperature and high-humidity environment, and foaming, various evaluations have been made.

[Previous Technical Literature] [Patent Document 1]

Patent Document 1: Japanese Laid-Open Patent Publication 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 exhibiting excellent durability under high temperature and humidity conditions, and is used for further When an optical film such as a liquid crystal cell or a polarizing film is used, it is possible to reduce light leakage.

In order to solve such a problem, the inventors of the present invention have found that when an adhesive layer is formed using an adhesive composition containing a crosslinking agent having a specific structure and used for an optical film such as a liquid crystal cell or a polarizing film. Reduce light leakage.

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

(wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having 1 or more and 14 or less carbon atoms),

(In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkyl group having 2 or more and 10 or less carbon atoms),

(In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkylene group having 2 or more and 10 or less carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E and R ^3F are independently an alkylene group having a carbon number of 2 or more and 10 or less. Base),

(wherein x is an integer of 2 or more and 10 or less, and m is an integer of 1 or more and 10 or less);

(wherein, X represents a single bond or -O-, y is an integer of 2 or more and 10 or less, and n is an integer of 1 or more and 10 or less).

2. The adhesive composition for an optical film according to the above-mentioned item 1, wherein the (B) crosslinking agent is contained 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 above formula (1) (a1). The above 99.9 mass% or less and (a2) are 0.1% by mass or more and 10% by mass or less of a monomer having one olefinic double bond and at least one hydroxyl group in the molecule.

4. The adhesive composition for an optical film according to any 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) acrylate monomer represented by the above formula (1) (a1): (a1-1) It is assumed that the glass transition temperature (Tg) in the case of forming a homopolymer is 0 ° C In the above, the (meth) acrylate monomer represented by the above formula (1) is 5% by mass or more and 55% by mass or less; (a1-2) the glass transition temperature (Tg) assuming that a homopolymer is formed. When it is less than 0 ° C, the (meth) acrylate monomer represented by the above formula (1) is from 44.5 mass% to 94.5 mass%; (The total amount of the above (a1-1) and the above (a1-2) is 90.1% by mass or more and 100% by mass or less).

The adhesive composition for an optical film according to any one of the above-mentioned (1), wherein the (C) decane coupling agent is contained in an amount of 0.01 part by mass or more based on 100 parts by mass of the (A) acrylic polymer. 0.5 parts by mass or less.

The adhesive composition for an optical film according to any one of the above (1), wherein the (D) ionic compound is contained in an amount of 0.01 parts by mass or more based on 100 parts by mass of the (A) acrylic polymer. 3 parts by mass or less.

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

8. The adhesive optical film according to another aspect of the present invention, wherein the adhesive layer comprising the adhesive composition for an optical film according to any one of the above 1 to 7 is provided on one or both sides of the optical film. surface.

9. The adhesive optical film according to the above 8, which 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 enhancement film, and a light diffusing film.

The adhesive composition for an optical film contains the component (B), and the component represented by the above formula (4) and/or the group represented by the above formula (5) is contained in the component (B). The adhesive composition has a certain hardness and imparts a moderate cohesive force and elasticity to the adhesive composition. Thereby, the adhesive composition can have a trade-off relationship. Both cohesion and elasticity. Therefore, the adhesive composition has a moderate adhesive force, exhibits excellent durability (humidity resistance) under high temperature conditions or under high temperature and humidity conditions, and is used for adhering to a liquid crystal cell or the like, and a polarizing film. When the optical film is used, light leakage can be reduced.

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

100‧‧‧Image display device (liquid crystal panel)

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

Lcenter‧‧‧Brightness of the central part of the image display device

Fig. 1 is a view schematically showing a method of measuring the brightness of an image display device (liquid crystal display panel, vertical alignment (VA)) according to an embodiment of the present invention.

Fig. 2 is a view schematically showing a method of measuring the brightness of an image display device (liquid crystal display panel, TN (Twisted Nematic) type) according to an embodiment of the present invention.

The invention will be described in detail below with reference to the drawings. Further, in the present invention, unless otherwise specified, "parts" means "parts by mass", and "%" means "mass%".

1. Adhesive composition for optical film

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

(In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkyl group having 2 or more and 10 or less carbon atoms),

(In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkylene group having 2 or more and 10 or less carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E and R ^3F are independently an alkylene group having a carbon number of 2 or more and 10 or less. Base),

(wherein x is an integer of 2 or more and 10 or less, and m is an integer of 1 or more and 10 or less),

(wherein, X represents a single bond or -O-, y is an integer of 2 or more and 10 or less, and n is an integer of 1 or more and 10 or less).

1.1. (A) component

The component (A) is an acrylic polymer obtained by containing (a1) a (meth) acrylate monomer represented by the following formula (1) and (a2) having one olefinic double in the molecule. A monomer mixture of a bond with a monomer of at least one hydroxyl group.

(wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having 1 or more and 14 or less carbon atoms).

In the present invention, the "acrylic polymer" refers to a polymerization comprising at least one selected from the group consisting of acrylic acid, acrylate, acrylate, methacrylic acid, methacrylic acid salt, and methacrylic acid ester in a constituent unit of 50% by mass or more. Things. Further, 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 moiety.

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

Further, in the present invention, the "aralkyl group" means an alkyl group in which one hydrogen atom of the alkyl group is substituted with an aryl group. In the above formula (1), the aralkyl group having 1 or more and 14 or less carbon atoms represented by R ₂ may, for example, be a benzyl group (benzyl group) or a benzyl group (phenethyl group).

The content of the component (A) of the adhesive composition of the present embodiment may be 90% by weight based on 100 parts by mass of the adhesive composition of the present embodiment. The mass fraction is 99.4 parts by mass or less, preferably 95 parts by mass or more and 99.4 parts by mass or less.

The adhesive composition of the present embodiment exhibits better adhesion and more excellent durability, and can be used to more effectively reduce light leakage when used for an optical film such as a liquid crystal cell or a polarizing film. From the viewpoint, the component (A) is preferably a polymer comprising a monomer mixture of the following (a1) and (a2) monomers: (a1) a (meth) acrylate single represented by the above formula (1) The body (hereinafter simply referred to as "(a1) component") is 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), and (a2) has one olefinic double bond in the molecule. The monomer having at least one hydroxyl group (hereinafter simply referred to as "(a2) component") is 0.1% by mass or more and 10% by mass or less (preferably 0.6% by mass or more and 7% by mass or less, more preferably 0.6% by mass or more and 6% by mass). %the following). In this case, the total amount of the component (a1) and the component (a2) is preferably from 90.1% by mass to 100% by mass.

1.1.1. (a1) ingredients

The component (a1) enhances the adhesion and durability of the adhesive composition of the present embodiment. With regard to (a1) the (meth) acrylate monomer represented by the above 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) acrylate monomer represented by the above formula (1) above °C (hereinafter simply referred to as "(a1-1) component").

In the case of the (meth) acrylate monomer represented by the above formula (1) in which the Tg of the component (a1-1) is 0 ° C or more in the case of forming a homopolymer, for example, acrylic acid A 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. a linear alkyl (meth) acrylate; a tertiary butyl acrylate, isopropyl methacrylate, isobutyl methacrylate, butyl methacrylate or the like having a branched alkyl group Alkyl (meth)acrylate monomer; cyclohexyl acrylate, cyclohexyl methacrylate, isodecyl acrylate, isodecyl methacrylate, dicyclopentanyl acrylate equivalent to an ester moiety having an alicyclic group (A) a (meth) acrylate monomer having an aromatic ring group such as benzyl methacrylate, benzyl acrylate or 2-naphthyl acrylate, wherein one type may be used alone or two or more types may be used in combination. use. In addition, the adhesive layer formed by using the adhesive composition of the present embodiment can further reduce the light leakage of the image display device, and the component (a1-1) is assumed to be represented by the above formula (1). The alkyl (meth) acrylate monomer having a Tg of 0 ° C or higher in the case of forming a homopolymer, and the alkyl chain system constituting the alkyl (meth) acrylate monomer is linear or branched The alkyl chain is preferred, and it is more preferred to have a branched alkyl chain. In this case, the use of the adhesive layer formed of the adhesive composition of the present embodiment can further reduce the light leakage of the image display device, and the carbon number of the alkyl chain is preferably 1 or more and 10 or less. It is particularly good to be 1 or more and 6 or less.

When the content of the component (a1-1) in the monomer mixture of the polymer for obtaining the component (A) is less than 5% by mass, the light leakage may not be sufficiently suppressed. On the other hand, if the content exceeds 55 mass %, there is a case where the adhesive layer becomes too hard, the adhesive treatment property is deteriorated, and the durability is adversely affected. In order to sufficiently suppress light leakage, adhesion with excellent durability is obtained. The content of the component (a1-1) in the monomer mixture for obtaining the polymer of the component (A) is preferably 5% by mass or more and 55% by mass or less, and preferably 5% by mass or more and 40% by mass or less. Better.

Further, (a1) the (meth) acrylate monomer represented by the above formula (1), for example, (a1-2) can be used, assuming that the glass transition temperature (Tg) in the case of forming a homopolymer is less than 0. The (meth) acrylate monomer represented by the above formula (1) at °C (hereinafter simply referred to as "(a1-2) component").

With respect to the (meth) acrylate represented by the above formula (1) in which the Tg of the component (a1-2) is not more than 0 ° C in the case of forming a homopolymer, for example, ethyl acrylate, N-propyl acrylate, n-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-amyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-decyl acrylate, methyl An alkyl (meth)acrylate monomer having a linear alkyl group such as lauryl acrylate, lauryl acrylate or n-tetradecyl methacrylate; isopropyl acrylate, isobutyl acrylate, isooctyl acrylate, and A a (meth)acrylic acid alkyl ester monomer having a branched alkyl group such as isooctyl acrylate, 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate; The alkyl (meth) acrylate monomer of the aromatic ring group may be used alone or in combination of two or more. In the case where the adhesive layer formed by the adhesive composition of the present embodiment can further reduce the light leakage point, the component (a1-2) assumes that the Tg in the case of forming a homopolymer is less than 0 ° C. The alkyl (meth)acrylate monomer represented by the above formula (1), and the alkyl chain constituting the alkyl (meth)acrylate is preferably a linear or branched alkyl chain. It is more preferable to have a linear alkyl chain. In this situation In the case where the adhesive layer formed of the adhesive composition of the present embodiment is used to further reduce the 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 component (a1-2) in the monomer mixture of the polymer for obtaining the component (A) is less than 44.5 mass%, the adhesive property may be unbalanced, and the adhesion to the adherend is insufficient. On the other hand, if it exceeds 94.5 mass%, there is a case where light leakage cannot be sufficiently suppressed. In order to obtain an adhesive layer which is excellent in light leakage and excellent in durability, the content of the component (a1-2) in the monomer mixture for obtaining the polymer of the component (A) is 44.5 mass% or more and 94. 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.

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

1.1.2. (a2) ingredients

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

1.1.3. (a3) ingredients

The monomer mixture of the polymer for obtaining the component (A) may further comprise (a3) a monomer having one olefinic double bond in the molecule and at least one reactive functional group other than the hydroxyl group (hereinafter also simple It is "(a3) ingredient"). In the present invention, the "reactive functional group" means a functional group reactive 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 a decylamine. a group based on an acid anhydride group.

The reactive functional group contained in the component (a3) can be efficiently crosslinked by the action of the hydroxyl group in the component (a2) of the isocyanate group in the component (B). The component (a3) may, for example, be carboxyethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate or N,N-diethyl methacrylate. Aminoethyl ester, acrylamide, N,N-dimethylaminopropyl acrylamide, diacetone acrylamide, propylene morpholine, acrylic acid, methacrylic acid, maleic acid, itaconic acid, Among them, one type or two or more types may be used in combination. Among them, in the point that the efficiency of forming the crosslinked structure is excellent, the component (a3) is preferably at least one selected from the group consisting of acrylic acid and alkylguanamine, and more preferably acrylic acid.

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

In the adhesive composition of the present embodiment, from the viewpoint of good adhesion and durability, and more reliably achieving reduction in light leakage. It is to be noted that the total amount of the above-mentioned (a1) component, (a2) component, and (a3) in the monomer mixture for obtaining the polymer of the component (A) may be 90.1% by mass or more and 100% by mass or less, and 95% by mass. More than 100% by mass or less is more preferable.

1.1.4. (a4) ingredients

Further, the monomer mixture of the polymer for obtaining the component (A) may further contain a monomer (a4) other than the components (a1) to (a3), which is a monomer having one olefinic double bond in the molecule. (The following is also simply referred to as "(a4) component"). Examples of the component (a4) include vinyl acetate, styrene, acrylonitrile, and a macromonomer having a radical polymerizable vinyl group at a monomer terminal polymerized with an ethylene group. The content of the component (a4) in the monomer mixture of the polymer for obtaining 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)

In the adhesive composition of the present embodiment, the aforementioned monomer mixture of the polymer for obtaining the component (A) is used in view of good adhesion and durability and a more reliable reduction in light leakage. The total amount of the component (a1), (a2), and (a3) and (a4) may be 90.1% by mass or more and 100% by mass or less, preferably 95% by mass or more and 100% by mass or less, more preferably 100% by mass or less.

Further, in the adhesive composition of the present embodiment, the adhesive layer formed of the adhesive composition of the present embodiment can further reduce the light leakage point, and is preferably a monomer having an epoxy alkyl group. It is 5% by mass or less, and more preferably contains no monomer having an alkylene oxide group. The monomer having an alkylene oxide group may, for example, be a (meth) propyl group having an alkylene oxide group in a side chain. An olefinic monomer, a reactive emulsifier having 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 epoxyalkyl group in the adhesive composition is 2% by mass or less. In particular, it is preferred that the content of the monomer having an epoxyalkyl group in the adhesive composition is 0% by mass or more and 2% by mass or less.

1.1.6.Tg

In the adhesive composition of the present embodiment, the Tg of the component (A) is preferably -70 ° C or more and 0 ° C or less from the viewpoint of good adhesion and durability and a reduction in light leakage more reliably. More preferably, it is -60 ° C or more and -10 ° C or less. Further, in the present invention, the Tg of the component (A) is a value calculated by the following formula (6) (form of FOX).

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

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

Further, since TgA calculated by the above formula (6) is an absolute temperature (K), it can be converted to Celsius temperature (°C) as needed.

Further, the glass transition temperature of the homopolymer prepared by the representative monomer is shown in Table 1 below, and more specifically, it is described, for example, in the Polymer Handbook Third Edition (Polymer Handbook Third Edition, Wiley-Interscience, 1999). )Wait.

1.1.7. Weight average molecular weight (Mw)

Further, in the adhesive composition of the present embodiment, the component A) preferably has a weight average molecular weight (Mw) of 500,000 or more from the viewpoint of good adhesion and durability and a more reliable reduction in light leakage. 2 million Next, it is better to be 800,000 or more and 1.8 million or less. In addition, the weight average molecular weight of the component (A) is obtained by GPC (colloidal permeation chromatography), and the weight average molecular weight (Mw) of the standard polystyrene is determined under the following conditions.

<GPC measurement conditions>

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

GPC column structure: the following 5 connected pipe columns (all made by Tosoh Corporation)

(1) TSK-GEL HXL-H (protective 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 rate: 1.0cm ³ / minute

Column temperature: 40 ° C

Further, in the component (A) of the present embodiment, the molecular weight distribution (weight average molecular weight/number average molecular weight) determined by GPC is preferably in the range of 4 or more and 7 or less. In the component (A), the molecular weight distribution is 7 or less, meaning that the ratio of the high molecular weight component is high and the ratio of the low molecular weight component is small, so that the adhesive layer obtained by using the component (A) can be maintained under the endurance test condition. The cohesive force can further improve the durability of the adhesive layer, and is preferable in this regard. Further, in the component (A), since the molecular weight distribution is 4 or more, the component (A) is a polymer having a certain molecular weight distribution, so that the adhesion of the component (A) can be contained. 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) contains the crosslinking agent represented by the above formula (2) or the above formula (3).

In the adhesive composition of the present embodiment, the above formula (2) or the above formula (3) is contained in view of imparting more excellent adhesion and durability, and more reliably preventing light leakage. ^Among the groups represented by the above formula (4), R ^1A , R ^1B and R ^{1C are} preferably an integer of 2 or more and 10 or less (more preferably 4 or more and 8 or less), and m is 1 or more and 10 or less. The following integers are more preferable (the best is an integer of 1 or more and 6 or less). Further, in the group represented by the above formula (5) of R ^1A , R ^1B and R ^1C contained in the above formula (2) or the formula (3), it is preferred that y is an integer of 2 or more and 10 or less. Further, an integer of 4 to 8 is more preferable, and n is preferably an integer of 1 or more and 10 or less, and more preferably an integer of 1 or more and 6 or less. Further, R ^1A , R ^1B , and R ^1C may be the same, or may be different, or may be a combination of plural numbers.

In the above formula (2) or the above formula (3), the alkylene group contained in R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F may be, for example, It is linear, branched, or cyclic, preferably linear. The alkylene group may, for example, be a methylene group, an ethylidene group, a propyl group, a butyl group, a hexyl group, a decyl group, a decyl group, a cyclohexyl group, a cyclohexane dimethylene group or the like. The carbon number of the alkylene group is preferably 2 or more and 10 or less, more preferably 4 or more and 8 or less. Further, R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F may themselves be an alkylene group. Further, R ^2A , R ^2B and R ^2C may be the same or different. Further, 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 crosslinking agent, and more specifically, the component (B) has a skeleton derived from trimethylolpropane as shown by the above formula (2) or the above formula (3). (O-CH ₂ -) ₃ -C-CH ₂ CH ₃ ), and isocyanate (-N=C=O) group.

The component (B) can be, for example, a degree of crosslinking (the number of isocyanate groups contained in one molecule (B) component) is 1 or more, from the viewpoint of imparting appropriate elasticity to the adhesive composition of the present embodiment. 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 ester or carboxylic acid) having trimethylolpropane and an isocyanate group.

In the adhesive composition of the present embodiment, 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, from the viewpoint of achieving both the cohesive force and the elasticity.

The adhesive composition of the present embodiment contains the group represented by the above formula (4) and/or the group represented by the above formula (5), which is contained in the component (B), by the component (B). The adhesive composition is given a moderate cohesive force and elasticity. Thereby, the adhesive composition can have both the cohesive force and the elasticity which are originally in a mutual compensation relationship. Therefore, when the adhesive composition is used to form the adhesive layer of the image display device, the adhesive composition can prevent light leakage and improve adhesion and durability (humidity 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 cause cracking; on the other hand, the adhesive composition When the material 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 bubbles entering, and there may be Poor appearance. On the other hand, the adhesive composition of the present embodiment contains the component (B), and the adhesive composition has a moderate cohesive force and elasticity, so that the adhesive layer can be prevented from being cracked, and the bubble can be prevented from entering the adhesive. Floor.

The content of the component (B) of the adhesive composition of the present embodiment is 0.05 in terms of 100 parts by mass of the component (A) of the present embodiment, from the viewpoint of preventing light leakage and improving adhesion and durability. The mass part is 5 parts by mass or less, preferably 0.1 part by mass or more and 4 parts by mass or less.

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

According to the adhesive composition for an optical film of the present embodiment, the crosslinking agent (B) represented by the above formula (2) or the above formula (3) may be less than the above formula (2) or A crosslinking agent having a structure represented by the above formula (3) (for example, NY 730A (seller: Mitsubishi Chemical Corporation), commercially available isocyanate crosslinking agent, L-45 (seller: Synthetic Chemical Co., Ltd.) ), CORONATE HL (Vendor: Nippon Polyurethane Co., Ltd.), etc.) more reliably reduce light leakage, and is excellent in durability (heat and humidity resistance).

1.3. Other ingredients

The adhesive composition for an optical film of the present embodiment further contains components other than the components (A) and (B) as needed. For example, without damaging Within the scope of the effects of the present invention, (C) a decane coupling agent (hereinafter simply referred to as "(C) component") and (D) an ionic compound can be formulated in the adhesive composition of the present embodiment (hereinafter also simply described) It is "(D) component"), an antioxidant, a UV absorber, an adhesive, a plasticizer, etc.

1.3.1. (C) decane coupling agent

When the adhesive composition for an optical film of the present embodiment contains the component (C), when the adhesive layer is formed on the surface of the adherend using the adhesive composition for an optical film of the present embodiment, it can be favorably maintained. Behind the adherend. The component (C) may be, for example, a fluorene-containing compound containing a polymerizable unsaturated group such as ethylene trimethoxy decane, ethylene triethoxy decane or methacryloxypropyl trimethoxy decane; Epoxy group structure such as propyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane矽 compound; 3-aminopropyltrimethoxydecane, N-(2-aminoethyl) 3-aminopropyltrimethoxydecane and N-(2-aminoethyl)-3-amine An amino group-containing hydrazine compound such as propylmethyldimethoxydecane; and 3-chloropropyltrimethoxydecane; an oligomeric decane coupling agent, etc., wherein the point of flaking is less likely to occur in a hot and humid environment In particular, a decane coupling agent having a functional group reactive with a functional group contained in the (meth)acryl-based copolymer (A) is preferred.

The content of the component (C) in the adhesive composition for an optical film of the present embodiment may be 0.01 parts by mass based on 100 parts by mass of the component (A) from the viewpoint of maintaining the adhesion to the adherend. The amount is 0.5 parts by mass or less, preferably 0.05 parts by mass or more and 0.3 parts by mass or less.

1.3.2. (D) ionic compounds

Further, the adhesive composition of the present embodiment may contain an ionic compound (D). When the adhesive composition of the present embodiment contains the component (D), when the adhesive composition of the present embodiment is used to form an adhesive layer on the surface of the adherend, the adherend can be effectively prevented from being charged. The component (D) may, for example, be an ionic compound containing an anion or a cation at 25 ° C in a liquid form or in a solid form, and specific examples thereof include an alkali metal salt and an ionic liquid (liquid at 25 ° C). , surfactants, etc.

Examples of the alkali metal salt include a compound containing an alkali metal cation such as lithium, sodium or potassium and an anion, and specific examples thereof 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, or the like.

Examples of the cation constituting the ionic liquid include a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, a cation having a pyrrole skeleton, an imidazolium cation, a tetrahydropyrimidinium cation, a dihydropyrimidinium cation, and the like. a pyrazolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, etc.; and an anion constituting the above ionic liquid, examples thereof include Cl ^- , Br ^- , I ^- , and 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.

Further, examples of the ionic compound include an ionic compound which is composed of the cation and the anion and is 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-dimethyl Base tetrafluoroborate, 1-ethyloxazole 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 dicyandiamide, 1-ethyl-3-methylimidazolium bis(trifluoromethyl) Sulfhydryl)imine, 1-ethyl-3-methylimidazolium bis(pentafluoroethanesulfonyl)imide, 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 trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluoro Butane sulfonate, 1-butyl-3-methylimidazolium double (three Methanesulfonyl)imide, 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) Sulfhydryl)imide, 1-methylpyrazolium tetrafluoroborate, 3-methylpyrazolium tetrafluoroborate, tetrahexylammonium bis(trifluoromethanesulfonyl)imide, diallyl Dimethylammonium tetrafluoroborate, diallyldimethyl Glycol trifluoromethanesulfonate, diallyldimethylammonium bis(trifluoromethanesulfonyl)imide, diallyldimethylammonium bis(pentafluoroethanesulfonyl)imide, 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)imide, N, N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(pentafluoroethanesulfonyl)imide, epoxypropyltrimethylammonium triflate, Epoxypropyltrimethylammonium bis(trifluoromethanesulfonyl)imide, epoxypropyltrimethylammonium bis(pentafluoroethanesulfonyl)imide, 1-butylpyridinium (trifluoromethyl) Sulfosyl)trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl)trifluoroacetamide, 1-ethyl-3-methylimidazolium (trifluoromethyl) Sulfhydryl)trifluoroacetamide, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (trifluoromethanesulfonyl)trifluoroacetamide, two Allyldimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, epoxypropyltrimethylammonium (trifluoromethanesulfonyl)trifluoroacetamide, N,N-dimethyl -N-B -N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N, N-dimethyl-N-ethyl-N-pentyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl-N-hexylammonium bis(trifluoromethyl) Sulfhydryl)imine, N,N-dimethyl-N-ethyl-N-heptyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-ethyl- N-decyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dipropylammonium bis(trifluoromethanesulfonyl)imide, N,N-di Methyl-N-propyl-N-butylammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-propyl-N-amylammonium bis(trifluoromethanesulfonate) Imino, N,N-dimethyl-N-propyl-N-hexylammonium bis(trifluoromethanesulfonyl)amine, N,N-dimethyl-N-propyl-N-heptyl Ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl -N-hexyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N-butyl-N-heptyl ammonium bis(trifluoromethanesulfonyl)imide, N,N - dimethyl-N-pentyl-N-hexyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-dimethyl-N,N-dihexyl ammonium bis(trifluoromethanesulfonyl) Imine, trimethylheptyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide , N,N-Diethyl-N-methyl-N-pentyl ammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptyl ammonium (Trifluoromethanesulfonyl) imine, N,N-diethyl-N-propyl-N-pentyl ammonium bis(trifluoromethanesulfonyl)imide, triethylpropylammonium double (three Fluoromethanesulfonyl)imide, triethylammonium bis(trifluoromethanesulfonyl)imide, triethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-di propyl-N-methyl-N-ethylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N-methyl-N-amylammonium bis(trifluoromethanesulfonate) Imine, N,N-dipropyl-N-butyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, N,N-dipropyl-N,N-dihexylammonium (trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-amylammonium bis ( Trifluoromethanesulfonyl)imide, N,N-dibutyl-N-methyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide, trioctylmethylammonium bis(trifluoromethyl) Sulfhydryl)imine, N-methyl-N-ethyl-N-propyl-N-amylammonium bis(trifluoromethanesulfonyl)imide, and the like.

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 surfactant include polyvinyl alkyl ethers such as polyethylene lauryl ether and polyethylene stearyl ether; and polyvinyl alkyl groups such as polyethylene octyl phenyl ether and polyvinyl decyl phenyl ether; Phenyl ethers; Yamanashi Polysorbate such as alcoholic anhydride monolaurate, sorbitan monostearyl ester, sorbitan trioleate, etc.; polyethylene sorbitan higher fatty acid ester such as polyethylene sorbitan monolaurate Polyethylene higher fatty acid esters such as polyethylene monolaurate and polyethylene monostearyl ester; glycerol higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride; polyethylene, polypropylene, polybutylene Polyoxyolefins such as olefins and such block copolymers.

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

Examples of the anionic surfactant include sodium laurate, sodium oleate, N-nonyl-N-methylglycine sodium salt, and polyvinyl lauryl ether carboxylate; and dodecylbenzene; a sulfonate such as sodium sulfonate, dialkyl sulfosuccinate or sodium dimethyl-5-sulfoisophthalate; sodium lauryl sulfate, sodium polyethyl lauryl ether sulfate, polyvinyl nonylphenyl a sulfate salt such as sodium ether sulfate; a phosphate salt such as sodium polyvinyl lauryl phosphate or sodium polyvinyl nonylphenyl ether phosphate.

The amphoteric surfactant may, for example, be a carboxybetaine type surfactant, an aminocarboxylate, an imidazolinium betaine, a lecithin or an alkylamine oxide. Further, other polymers may be used, such as a conductive polymer, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, or the like.

Among them, an organic salt which is particularly liquid at 25 ° C is 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, and 0.05 parts by mass or more, based on 100 parts by mass of the component (A) of the present embodiment. The following parts are preferred.

1.4. Polymerization method of component (A)

The polymerization method of the component (A) is not particularly limited, and polymerization can be carried out by a known method such as solution polymerization, emulsion polymerization or suspension polymerization, except that a mixture of the copolymers obtained by polymerization is used to produce the adhesive composition of the present invention. In the case where the treatment step is simple and can be carried out in a short period of time, it is preferred to carry out polymerization by solution polymerization.

In general, solution polymerization is carried out by charging a specific organic solvent, each monomer, a polymerization initiator, and a chain transfer agent as needed in a polymerization tank, and stirring at a reflux temperature of a nitrogen gas stream or an organic solvent. Heating is carried out for several hours.

Further, in this case, at least a part of the organic solvent, the monomer, and/or the polymerization initiator may be added successively. Examples of the organic solvent include benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, decalin, and aromatic. An aromatic hydrocarbon such as naphtha (anamatics naphtha); for example: n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirit, petroleum brain (petroleum) Naphtha), turpentine oil or other aliphatic or alicyclic hydrocarbons; for example: ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate And esters such as 3-methoxybutyl acetate and methyl benzoate; for example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methylcyclohexanone For example: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethyl a glycol ether such as a glycol monobutyl ether; for example, an alcohol such as methyl alcohol, ethyl alcohol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol or tertiary butanol ;Wait. These organic solvents may be used alone or in combination of two or more.

Among these organic solvents for polymerization, in the case of polymerizing the component (A), it is preferred to use an organic solvent which is less likely to undergo chain transfer during the polymerization reaction, and for example, an ester or a ketone is used, and particularly, the component (A) is used. It is more preferable to use ethyl acetate, methyl ethyl ketone, acetone or the like in terms of solubility, ease of polymerization, and the like.

As the polymerization initiator, an organic peroxide, an azo compound or the like which is generally used for solution polymerization can be used. Examples of such an organic peroxide include tertiary butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzamidine peroxide, and bay laurel. Base peroxide, hexyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, tertiary butyl peroxyisobutyrate, 2,2-dual 4,4-di-tertiary butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-triamylpentylperoxycyclohexyl)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-trioctyloctylperoxycyclohexyl)butane, etc.; azo compounds, for example, 2,2'- Azobis-isobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylpentyl Nitrile and the like.

Among these polymerization initiators, a polymerization initiator which does not undergo a graft reaction in the polymerization reaction of the component (A) is preferred, and an azo system is particularly preferred. Polymerization initiator. The amount thereof is generally 0.01 parts by mass or more and 2 parts by mass or less, preferably 0.1 parts by mass or more and 1.0 part by mass or less based on 100 parts by mass of the total of the monomers.

Further, when the component (A) contained in the adhesive composition of the present invention is produced, generally, a chain transfer agent is not used, but it can be used as long as it does not impair the object and effect of the present invention as needed.

Examples of such a chain transfer agent include cyanoacetic acid; alkyl esters having a carbon number of 1 or more and 8 or less; bromoacetic acid; alkyl ketone having a carbon number of 1 or more and 8 or less; , anthracene, 9-phenylindole and other aromatic compounds; p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene, etc. Nitro compounds; phenylhydrazine derivatives such as benzoquinone, 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrachloride, tetrachlorination Halogenated hydrocarbons such as carbon, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-propene; chloral, furfural Aldehydes such as (furaldehyde): alkyl mercaptans having a carbon number of 1 or more and 18 or less; aromatic mercaptans such as thiophenol and toluene mercaptan; and alkyl groups having 1 or more and 10 or less carbon atoms of indole acetic acid and indole acetic acid; Esters; hydroxyalkyl thiols having a carbon number of 1 or more and 12 or less; terpenes such as terpenes and terpinolene; and the like.

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

1.5. micro-creep value

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

As a result of the adhesive composition of the present 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 reliably prevent light leakage. In view of the above, it is preferred that the difference between the microscopic latent value at 60 ° C and the microscopic latent value at 23 ° C is small, for example, the microscopic latent value at 60 ° C and 23 ° C It is preferable that the difference in the microscopic creep value is within 0.30 mm.

1.6. Manufacture of adhesive composition

The adhesive composition of the present embodiment is generally prepared by mixing the components (A) and (B) and optional components as needed, either simultaneously or in any order. Further, 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 completion of the polymerization. In the case where the component (A) is prepared by bulk polymerization, since it becomes difficult to uniformly mix after the completion of the polymerization, it is preferred to add the component (B) in the middle of the polymerization and mix it.

1.7. Use and effect

The adhesive composition of the present embodiment can be suitably used as an adhesive for an optical film (described in detail later). According to the adhesive composition of the embodiment, It exhibits excellent durability under high temperature and humidity conditions, and it can reduce light leakage when it is used for an optical film such as a liquid crystal cell or a polarizing film. Further, when the image display device includes a retardation film, since a retardation film can be provided between the liquid crystal cell and the polarizing film, the adhesive composition of the present embodiment can be provided between the retardation film and the polarizing film. Agent layer.

For example, when the adhesive composition of the present embodiment is used for an optical film such as a liquid crystal cell or the like, and an optical film such as a polarizing film, excellent light leakage prevention characteristics and high durability can be achieved, so that a high image of the image display device can be achieved. Qualitative. In this case, the adhesive composition of the present embodiment can be used as a polarizing film for a VA mode, a polarizing film for a TN mode, or a polarizing film for an IPS mode as an adhesive for an adherend, thereby achieving high image quality. In addition, an adhesive which is a polarizing film in a VA mode or a polarizing film in a TN mode as an adherend can be suitably used.

The light leakage prevention characteristic which is one of the effects of the adhesive composition of the present embodiment is presumed to be due to the following mechanism of action.

In other words, when the adhesive composition is provided on the surface of the optical film (polarizing film) by using the adhesive composition of the present embodiment, the adhesive composition has the component (B) and is contained in the component (B). The base represented by the above formula (4) and/or the group represented by the above formula (5) has a certain hardness and imparts a moderate cohesive force to the adhesive composition. And flexibility. Thereby, the adhesive composition can have both the cohesive force and the elasticity which are originally in a mutual compensation relationship. Therefore, when the adhesive composition is used to form the adhesive layer of the image display device, light leakage can be prevented, and adhesion and durability (humidity resistance) can be improved.

2. Adhesive optical film

In the adhesive optical film according to another embodiment of the present invention, the adhesive layer containing the adhesive composition for an optical film of the above embodiment is provided on one surface or both surfaces of the optical film. In the production of the adhesive optical film of the present embodiment, the adhesive layer may be a gravure coater, a Meyer bar coater, an air knife coater, or a roll by using the adhesive composition. a coater 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 The adhesive layer is formed by transferring it to the above optical film. Further, the thickness of the adhesive layer is generally from 1 μm to 50 μm, preferably from about 5 μm to about 30 μm. Further, before the adhesive optical film is used, the film may be peeled off from the surface layer of the adhesive layer to protect the adhesive layer.

Further, the adhesive optical film of the present embodiment may be a user such as 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 elliptically polarizing film, an antireflection film, a brightness enhancement film, and a light diffusing film. The thickness of the optical film can be appropriately selected depending on the purpose of use, and is generally 10 μm or more and 500 μm or less, preferably 15 μm or more and 300 μm or less.

(Example)

3. Embodiment

The invention is illustrated by the following examples, but the invention is not limited to the examples.

3.1. Modulation of component (A)

In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas introduction tube, a monomer mixture having a blending ratio shown in Table 2 below was charged, and then, ethyl acetate was charged to adjust the amount of the monomer to a monomer concentration. 50% by mass. Then, 0.1 part by mass of azobisisobutyronitrile was added, and the air in the reaction vessel was replaced with a nitrogen gas while stirring, and the temperature was raised to 60 ° C, and then reacted for 8 hours. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain a component (A) (acrylic polymers A to G).

3.2. Evaluation of the production of adhesive processing polarizing plates

Using the component (A) obtained in the above 3.1, and adding each component according to the formulation (solid content formulation) of the following Tables 3 and 4, a solution of the adhesive compositions of Examples 1 to 15 and Comparative Examples 1 to 11 was obtained. . The adhesive composition of the adhesive composition was applied onto the surface of the release-treated polyester film and dried to obtain an adhesive sheet having an adhesive layer having a thickness of 20 μm. The adhesive sheet was adhered to one side of the polarizing film for VA mode, and then immersed in a dark place for 7 days under conditions of 23 ° C / 50% RH to obtain an adhesive-processed polarizing plate for evaluation. Further, as the component (B), as shown in the following Tables 3 and 4, the crosslinking agents 1 to 6 were used. The crosslinking agents 1 to 6 have the configurations shown in the following structural formulas (7) to (12), respectively. Further, the crosslinking agent 1 has a weight average molecular weight (MW) of about 3,700, the crosslinking agent 2 has a weight average molecular weight (MW) of about 4,000, and the crosslinking agent 3 has a weight average molecular weight (MW) of about 4,000.

[Crosslinking agent 1]

(wherein 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]

(wherein l is 1 or more and 10 or less, and m is 1 or more and 10 or less, n It is 1 or more and 10 or less).

[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 the adhesion processing polarizing plates for each evaluation, use the following The method evaluates the maximum deformation rate, strain recovery rate, light leakage (LED for light source: LED method), light leakage (light source is not used for LED: non-LED method), and heat and humidity resistance (bubble) as shown in Tables 3 and 4 below. And break).

3.3. Evaluation method

3.3.1. Light leakage

The adhesive-processed polarizing plate for which the peeled-treated polyester film has been peeled off is adhered to the liquid crystal panel by an adhesive, and the evaluation adhesive-bonding polarizing plate is a method of crossed nicols. A VA type liquid crystal panel (manufactured by I.O DATA Co., Ltd., type: taken by LCD-A191EW), placed in an environment of 80 ° C for 240 hours, and placed in an environment of 23 ° C / 50% RH 2 hours. Thereafter, the liquid crystal panel to which the polarizing plate described above is attached is connected to a computer in a dark room, and a black screen is displayed. In this test, two types of panels, a VA liquid crystal panel and a TN liquid crystal panel, were used as the liquid crystal panel for evaluation. For the display screen on which the black screen is displayed, the luminance (La, Lb) of a region having a diameter of 1 cm in the vicinity of each corner as shown in Fig. 1 was measured using a luminance meter (manufactured by HI-LAND Co., Ltd., model: RISA-COLOR/CD8). , Lc, Ld) and the luminance (Lcenter) of a region having a diameter of 1 cm in the central portion of the screen, and the light leakage property (ΔL) is calculated according to the following formula (13). The smaller the ΔL is, the smaller the light leakage (from the backlight) is. Generally, as long as ΔL is less than 2.0, it can be used as a panel for liquid crystal display.

△L=(La+Lb+Lc+Ld)/4-Lcenter‧‧‧(13)

Further, for the VA liquid crystal panel, the range (R) of light leakage occurring near the corner of the display screen as indicated by the broken line in FIG. 1 was visually measured, and the liquid crystal panel of the TN mode was visually observed. The range (R) of light leakage occurring near the periphery of the display screen as indicated by the broken line in Fig. 2 is determined. The smaller the range in which light leakage occurs, the smaller the light leakage is. Generally, as long as R is less than 20 mm, it can be used as a panel for liquid crystal display. More preferably, it is less than 16.5 mm.

3.3.2. Microscopic latent value

Each of the evaluation adhesive-coated polarizing plates was cut into a width of 10 mm × a length of 100 mm, and each of the adhesive-coated polarizing plates for which the peeled-off polyester film was peeled off was adhered to the glass with an adhesive layer, and the bonding area was changed. The film was bonded in a manner of 100 mm ² (10 mm × 10 mm), and after autoclaving (50 ° C, 5 atm), it was allowed to stand in an environment of 23 ° C / 50% RH for 24 hours. The obtained one was used as a sample for the microscopic creep test. The length of the fixing jig portion in the test chamber of the micro-vision potential measuring machine (manufactured by Yinghong Seiki Co., Ltd., model name: TA.TX.PLUS) was 15 mm, and the test sample was placed. When the test data was fixed up and down and a load of 800 g was applied for 1000 seconds in the vertical direction, the offset distance of the bonded end portion of the sample and the adherend was compared with the initial.

3.3.3. Humidity resistance

The adhesive-processed polarizing plate for peeling off the peeled-treated polyester film was cut into 15 吋 (233 mm × 309 mm), and adhered to the thickness of 0.5 mm using a laminating roller in such a manner that the adhesive layer was in contact with the above-mentioned glass plate. One side of an alkali glass plate. After the adhesion, the test plate was obtained by pressurization with an autoclave (manufactured by Kurihara Seisakusho Co., Ltd.) at 0.5 MPa, 50 ° C, and 20 minutes. The test plate thus obtained was placed under conditions of 60 ° C / 90% RH for 500 hours. After the end of the test, the test plate was taken out from the test environment, and after standing at 23 ° C / 50% RH for 2 hours, the foaming of the adhesive layer was observed visually (insufficient cohesive force), The fracture (overcrosslinking) was evaluated, and the heat and humidity resistance was evaluated on the basis of the following evaluation criteria.

(bubble-size)

○: No foaming at all

△: The diameter of the foam is less than 1 mm

×: The diameter of the foam is larger than 1 mm.

(bubble-production amount)

○: No foaming at all

△: The number of foaming is less than 10

×: The number of blistering is more than 10

(fracture-size)

○: No breaks were seen at all

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

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

(fracture-position)

○: no break at all

△: Defective only in the 1 cm width region near each end of the test plate

×: a 1 cm width region near each end portion of the test plate and a defect outside the region

Further, the abbreviation of Table 2 means the following meaning.

AA: Acrylic

BA: n-butyl acrylate

t-BA: tertiary (tert-) butyl acrylate

4-HBA: 4-hydroxybutyl acrylate

HEA: 2-hydroxyethyl acrylate

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

MA: Methyl acrylate

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

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

From the results of Tables 3 and 4, it is understood that the compositions of the above Examples 1 to 15 are composed of the crosslinking agents 1 to 3 represented by the above formula (2) or the above formula (3) as the component (B). , to achieve high adhesion and excellent durability, and to reduce light leakage. On the other hand, the compositions of Comparative Examples 1 to 11 did not contain the crosslinking agent represented by the above formula (2) or the above formula (3) as the component (B) (the crosslinking agent used was 4 to 6). The structure represented by the above formula (2) or the above formula (3) (Comparative Examples 1 to 11) does not sufficiently reduce the light leakage.

(industrial availability)

The drawing of the present invention is a diagram illustrating a method for measuring the brightness of the image display device of the embodiment of the present invention, which is not sufficient to represent the technical features of the present invention.

Claims (9)

An adhesive composition for an optical film comprising: (A) an acrylic polymer comprising (a1) a (meth) acrylate monomer represented by the following formula (1) and (a2) a molecule a polymer having a monomer mixture of one olefinic double bond and at least one hydroxyl group, (B) a crosslinking agent represented by the following formula (2) or the following formula (3); (wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having 1 or more and 14 or less carbon atoms), (In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkylene group having 2 or more and 10 or less carbon atoms, (In the formula, R ^1A , R ^1B and R ^1C are each independently a group including a group represented by the following formula (4) and/or a group represented by the following formula (5), and R ^2A and R ^2B ; R ^2C is independently a group containing an alkylene group having 2 or more and 10 or less carbon atoms, and R ^3A , R ^3B , R ^3C , R ^3D , R ^3E and R ^3F are independently an alkylene group having a carbon number of 2 or more and 10 or less. Base), (wherein x is an integer of 2 or more and 10 or less, and m is an integer of 1 or more and 10 or less), (wherein, X represents a single bond or -O-, y is an integer of 2 or more and 10 or less, and n is an integer of 1 or more and 10 or less). The adhesive composition for an optical film according to the above aspect of the invention, wherein the (B) crosslinking agent is contained in an amount of 0.05 parts by mass or more and 5 parts by mass based on 100 parts by mass of the (A) acrylic polymer. the following. The adhesive composition for an optical film according to the above aspect of the invention, wherein the monomer mixture comprises the (meth) acrylate monomer represented by the above formula (1) (a1). 90% by mass or more and 99.9% by mass or less and (a2) 0.1% by mass or more and 10% by mass or less of a monomer having one olefinic double bond and at least one hydroxyl group in the molecule. The adhesive composition for an optical film according to claim 3, wherein the monomer mixture comprises the (meth) acrylate monomer represented by (a1-1) and (a1-2) as the aforementioned ( A1) The (meth) acrylate monomer represented by the above formula (1): (a1-1) assumes that the glass transition temperature (Tg) in the case of forming a homopolymer is 0 ° C or more, the above formula ( 1) The (meth) acrylate monomer shown is 5% by mass or more and 55% by 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 formula (1) is 44.5 mass% or more and 94. mass% or less (wherein the total amount of the above (a1-1) and the above (a1-2) is 90.1% by mass or more and 100%. Below mass%). An optical film according to any one of claims 1 to 4 In the adhesive composition, the (C) decane coupling agent is contained in an amount of 0.01 parts by mass or more and 0.5 parts by mass or less based on 100 parts by mass of the (A) acrylic polymer. The adhesive composition for an optical film according to any one of the above-mentioned (A) acrylic polymer, which is 0.01 parts by mass or more and 3 parts by mass based on 100 parts by mass of the acrylic polymer (A). The following (D) ionic compound. The adhesive composition for an optical film according to any one of claims 1 to 6, wherein the microscopic latent value at 60 ° C is 0.50 mm or less. An adhesive type optical film comprising an adhesive layer of an adhesive composition for an optical film according to any one of the first to seventh aspects of the invention, which is provided on one or both sides of the optical film. The adhesive optical film according to claim 8, which is selected from the group consisting of a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and an optical film in a group of light diffusing films.