JP6321629B2 - Adhesive composition for optical film and adhesive optical film - Google Patents

Description

  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 applications and conditions. For example, they are often used not only under room temperature conditions but also under severe conditions such as high temperature and high temperature and humidity. . Examples of the use under a high temperature or high temperature and humidity condition include use in a tropical region, use inside a vehicle, and inside an outdoor measuring instrument.

  An optical film such as a polarizing film constituting the image display device is produced by adsorbing a dichroic dye to a polymer film such as polyvinyl alcohol, and stretching and orienting the film. For this reason, the optical film is easily shrunk in a high temperature or high humidity environment and is likely to undergo dimensional deformation. Moreover, once dimensional deformation occurs in the optical film, it is difficult to completely return to the original dimensions even if the temperature and humidity conditions are changed. As a result, the pressure-sensitive adhesive layer is cracked, peeled off or floated due to the influence of the stress caused by the dimensional change of the optical film, or light leakage due to the polarization axis distortion occurs in the image display device.

  Further, in recent years, there has been a demand for an image display apparatus having a large screen, high image quality, and high durability. Along with this, various studies have been made on the pressure-sensitive adhesive composition to solve defects in appearance such as light leakage caused by dimensional change of an optical film such as a polarizing film, peeling in a high-temperature and high-humidity environment, and foaming. Yes.

JP 2007-169329 A

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

  In order to solve such problems, the present inventors formed a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition containing a cross-linking agent having a predetermined structure, such as an adherend such as a liquid crystal cell and a polarizing film. It has been found that light leakage can be reduced when used for adhesion to an optical film.

1. The pressure-sensitive adhesive composition for an optical film according to one aspect of the present invention,
(A) (a1) a (meth) acrylate monomer represented by the following general formula (1) and (a2) a monomer having one olefinic double bond and at least one hydroxyl group in the molecule An acrylic polymer that is a polymer of a monomer mixture containing a monomer;
(B) a crosslinking agent represented by the following general formula (2) or the following general formula (3).

・・・・（１）
（式中、Ｒ^１は水素原子またはメチル基を表し、Ｒ^２は炭素数１以上１４以下のアルキル基またはアラルキル基を表す。）

(1)
(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 1 to 14 carbon atoms.)

・・・・（２）
（式中、Ｒ^１Ａ，Ｒ^１Ｂ，Ｒ^１Ｃは独立して、下記一般式（４）で表される基および／または下記一般式（５）で表される基を含む基であり、Ｒ^２Ａ，Ｒ^２Ｂ，Ｒ^２Ｃは独立して、炭素原子数２以上１０以下のアルキレン基を含む基である。）

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

・・・・（３）
（式中、Ｒ^１Ａ，Ｒ^１Ｂ，Ｒ^１Ｃは独立して、下記一般式（４）で表される基および／または下記一般式（５）で表される基を含む基であり、Ｒ^２Ａ，Ｒ^２Ｂ，Ｒ^２Ｃは独立して、炭素原子数２以上１０以下のアルキレン基を含む基であり、Ｒ^３Ａ，Ｒ^３Ｂ，Ｒ^３Ｃ，Ｒ^３Ｄ，Ｒ^３Ｅ，Ｒ^３Ｆは独立して、炭素原子数２以上１０以下のアルキレン基を含む基である。）

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

・・・・（４）
（式中、ｘは２以上１０以下の整数であり、ｍは１以上１０以下の整数である。）

.... (4)
(In the formula, x is an integer of 2 to 10, and m is an integer of 1 to 10.)

・・・・（５）
（式中、Ｘは単結合または−Ｏ−を表し、ｙは２以上１０以下の整数であり、ｎは１以上１０以下の整数である。）

(5)
(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. Said 1 adhesive composition for optical films WHEREIN: 0.05 mass part or more and 5 mass parts or less of said (B) crosslinking agent can be included with respect to 100 mass parts of said (A) acrylic polymers.

  3. In the pressure-sensitive adhesive composition for optical film according to 1 or 2, the monomer mixture is 90% by mass or more and (99) 99% by mass or more of the (meth) acrylate monomer represented by the general formula (1). 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 can be contained.

  4). 4. The optical film pressure-sensitive adhesive composition according to any one of 1 to 3, wherein the monomer mixture is (a1) a (meth) acrylic acid ester monomer represented by the general formula (1). (A1-1) (meth) acrylate monomer represented by the above general formula (1) having a glass transition temperature (Tg) of 0 ° C. or higher when it is assumed that a homopolymer is formed 5 mass (Meth) acrylic represented by the above general formula (1) having a glass transition temperature (Tg) of less than 0 ° C. assuming that (a1-2) a homopolymer is formed. Acid ester monomer 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%). % Or less).

  5. 5. The optical film pressure-sensitive adhesive composition according to any one of 1 to 4, wherein (C) silane coupling agent is 0.01 part by mass or more and 0.5 part by mass with respect to 100 parts by mass of (A) acrylic polymer. The following may further be included.

  6). In the pressure-sensitive adhesive composition for an optical film according to any one of 1 to 5, (D) 0.01 part by mass or more and 3 parts by mass or less of an ionic compound with respect to 100 parts by mass of the acrylic polymer (A). Further can be included.

  7). In the pressure-sensitive adhesive composition for an optical film according to any one of 1 to 6, a micro creep value at 60 ° C. may be 0.50 mm or less.

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

  9. The adhesive optical film described in 8 above can 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 diffusion film.

  When the optical film pressure-sensitive adhesive composition contains the component (B), the group represented by the general formula (4) and / or the group represented by the general formula (5) contained in the component (B). Due to the group containing, suitable cohesive force and elasticity are imparted to the pressure-sensitive adhesive composition while the pressure-sensitive adhesive composition has a certain degree of hardness. Accordingly, the pressure-sensitive adhesive composition can have both cohesive force and elasticity, which are often often in a trade-off relationship. Therefore, the pressure-sensitive adhesive composition has an appropriate pressure-sensitive adhesive force, exhibits excellent durability under high-temperature conditions or high-temperature and high-humidity conditions (wet heat durability), and adherends such as liquid crystal cells and polarizing films When used for adhesion to an optical film such as the above, light leakage can be reduced. In addition, the pressure-sensitive adhesive optical film using the pressure-sensitive adhesive composition for an optical film is adhered to an adherend such as a liquid crystal cell with an appropriate adhesive force, and has excellent durability under high temperature conditions or high temperature and high humidity conditions. When it is used for adhesion to an adherend such as a liquid crystal cell, light leakage can be reduced.

FIG. 1 is a diagram schematically illustrating a method for measuring the luminance of an image display device (liquid crystal display panel, VA method) in an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a method for measuring the luminance of the image display device (liquid crystal display panel, TN method) in the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, “parts” means “parts by mass” and “%” means “mass%” unless otherwise specified.

1. Optical film pressure-sensitive adhesive composition The optical film pressure-sensitive adhesive composition according to an embodiment of the present invention (hereinafter sometimes simply referred to as “pressure-sensitive adhesive composition”) is an acrylic polymer (A) (hereinafter referred to as “pressure-sensitive adhesive composition”). May be simply referred to as “component (A)”) and a crosslinking agent (B) represented by the following general formula (2) or the following general formula (3) (hereinafter simply referred to as “component (B)”). In some cases).

・・・・（２）
（式中、Ｒ^１Ａ，Ｒ^１Ｂ，Ｒ^１Ｃは独立して、下記一般式（４）で表される基および／または下記一般式（５）で表される基を含む基であり、Ｒ^２Ａ，Ｒ^２Ｂ，Ｒ^２Ｃは独立して、炭素原子数２以上１０以下のアルキレン基を含む基である。）

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

・・・・（３）
（式中、Ｒ^１Ａ，Ｒ^１Ｂ，Ｒ^１Ｃは独立して、下記一般式（４）で表される基および／または下記一般式（５）で表される基を含む基であり、Ｒ^２Ａ，Ｒ^２Ｂ，Ｒ^２Ｃは独立して、炭素原子数２以上１０以下のアルキレン基を含む基であり、Ｒ^３Ａ，Ｒ^３Ｂ，Ｒ^３Ｃ，Ｒ^３Ｄ，Ｒ^３Ｅ，Ｒ^３Ｆは独立して、炭素原子数２以上１０以下のアルキレン基を含む基である。）

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

・・・・（４）
（式中、ｘは２以上１０以下の整数であり、ｍは１以上１０以下の整数である。）

.... (4)
(In the formula, x is an integer of 2 to 10, and m is an integer of 1 to 10.)

・・・・（５）
（式中、Ｘは単結合または−Ｏ−を表し、ｙは２以上１０以下の整数であり、ｎは１以上１０以下の整数である。）

(5)
(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. Component (A) Component (A) is composed of (a1) a (meth) acrylic acid ester monomer represented by the following general formula (1) and (a2) one olefinic double bond in the molecule and at least 1 It is an acrylic polymer obtained from a monomer mixture containing a monomer having a number of hydroxyl groups.

・・・・（１）
（式中、Ｒ^１は水素原子またはメチル基を表し、Ｒ^２は炭素数１以上１４以下のアルキル基またはアラルキル基を表す。）

(1)
(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 1 to 14 carbon atoms.)

  In the present invention, the “acrylic polymer” means at least one selected from acrylic acid, acrylic acid salt, acrylic acid ester, methacrylic acid, methacrylic acid salt, and methacrylic acid ester in a structural unit of 50% by mass or more. Refers to the polymer containing. In the present invention, “olefinic double bond” refers to a carbon-carbon double bond (C═C). For this reason, "a 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, such as a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylbutyl group, 1-methylbutyl group, n-hexyl Group, isohexyl group, 3-methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, n-heptyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group , N-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group (myristyl group) and the like. Among preferably has an alkyl group having 1 to 10 carbon atoms as R ^2, and more preferably has 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 of the hydrogen atoms of the 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 a benzyl group (phenylmethyl group) and a phenethyl group (phenylethyl group).

  The content of the component (A) in the pressure-sensitive adhesive composition according to this embodiment can be 90 parts by mass or more and 99.4 parts by mass or less with respect to 100 parts by mass of the pressure-sensitive adhesive composition according to this embodiment. It is preferably 95 parts by mass or more and 99.4 parts by mass or less.

  In the pressure-sensitive adhesive composition according to this embodiment, when exhibiting better adhesive strength and superior durability, and used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film From the viewpoint of more effectively reducing light leakage, the component (A) is (a1) a (meth) acrylate monomer represented by the general formula (1) (hereinafter simply referred to as “(a1) component”). 90 mass% or more and 99.9 mass% or less (preferably 92 mass% or more and 98.9 mass% or less) and (a2) at least one olefinic double bond in the molecule and at least Monomer having one hydroxyl group (hereinafter sometimes simply referred to as “component (a2)”) 0.1% by mass to 10% by mass (preferably 0.6% by mass to 7% by mass) Or less, more preferably 0.6 mass% or more and 6 mass% It is preferably a polymer of a monomer mixture comprising below). 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) component (a1) A component can contribute to the adhesive force and durability of the adhesive composition which concerns on this embodiment. (A1) As the (meth) acrylic acid ester monomer represented by the general formula (1), for example, (a1-1) the glass transition temperature (Tg) when assuming that a homopolymer is formed is 0 ° C. The (meth) acrylic acid ester monomer represented by the above general formula (1) (hereinafter sometimes simply referred to as “(a1-1) component”) can be used.

  As the (meth) acrylic acid ester monomer represented by the above general formula (1) having a Tg of 0 ° C. or more when it is assumed that a homopolymer is formed as the component (a1-1), for example, Linear alkyl groups such as methyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, n-butyl methacrylate, n-hexadecyl acrylate, n-hexadecyl methacrylate, stearyl acrylate, stearyl methacrylate (Meth) acrylic acid alkyl ester having; (meth) acrylic acid alkyl ester monomer having a branched alkyl group such as tert-butyl acrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate; (Meth) acrylic acid ester monomers having an alicyclic group at the ester site such as hexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, dicyclopentanyl acrylate; benzyl methacrylate, benzyl acrylate, 2-naphthyl Examples include (meth) acrylic acid ester monomers having an aromatic ring group such as acrylate. Among them, one kind can be used alone, or two or more kinds can be used in combination. Among these, (a1-1) component is the said General formula (1) by the point that the adhesive layer formed using the adhesive composition which concerns on this embodiment can reduce the light leak of an image display apparatus more. A (meth) acrylic acid alkyl ester monomer having a Tg of 0 ° C. or more when it is assumed that a homopolymer is formed, and the alkyl constituting the (meth) acrylic acid alkyl ester monomer The chain is preferably a linear or branched alkyl chain, and more preferably has a branched alkyl chain. In this case, the number of carbon atoms of the alkyl chain is 1 or more and 10 or less in that the adhesive layer formed using the adhesive composition according to this embodiment can further reduce the light leakage of the image display device. Is more preferable, and it is particularly preferably 1 or more and 6 or less.

  When the content of the component (a1-1) in the monomer mixture for obtaining the polymer as the component (A) is less than 5% by mass, light leakage may not be sufficiently suppressed. On the other hand, when it exceeds 55% by mass, the pressure-sensitive adhesive layer becomes too hard, and the workability of sticking may be deteriorated or the durability may be adversely affected. In order to obtain a pressure-sensitive adhesive layer that sufficiently suppresses light leakage and has excellent durability, inclusion of the component (a1-1) in the monomer mixture for obtaining the polymer as the component (A) The amount is preferably 5% by mass or more and 55% by mass or less, and more preferably 5% by mass or more and 40% by mass or less.

  Moreover, (a1) As a (meth) acrylic acid ester monomer represented by the general formula (1), for example, (a1-2) a glass transition temperature (Tg) when a homopolymer is assumed to be formed. The use of a (meth) acrylic acid ester monomer represented by the above general formula (1) (hereinafter sometimes simply referred to as “component (a1-2)”) that is less than 0 ° C. it can.

  As the (meth) acrylic acid ester represented by the above general formula (1) having a Tg of less than 0 ° C. assuming that a homopolymer is formed as the component (a1-2), for example, ethyl acrylate , N-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-pentyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, lauryl methacrylate, lauryl (Meth) acrylic acid alkyl ester monomers having a linear alkyl group such as acrylate and n-tetradecyl methacrylate; isopropyl acrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethyl methacrylate (Meth) acrylic acid alkyl ester monomers having a branched alkyl group such as ruhexyl acrylate and 2-ethylhexyl methacrylate; (meth) acrylic acid alkyl ester monomers having an aromatic ring group such as phenoxyethyl acrylate, Of these, one can be used alone or two or more can be used in combination. Among these, (a1-2) component is Tg when it is assumed that the adhesive layer formed using the adhesive composition which concerns on this embodiment can reduce light leakage more, and the homopolymer was formed. Is a (meth) acrylic acid alkyl ester monomer represented by the above general formula (1), wherein the alkyl chain constituting the (meth) acrylic acid alkyl ester is linear or branched It is preferably a linear alkyl chain, and more preferably has a linear alkyl chain. In this case, the number of carbon atoms of the alkyl chain is 1 or more and 10 or less in that the adhesive layer formed using the adhesive composition according to this embodiment can further reduce the light leakage of the image display device. Is more preferable.

  When the content of the component (a1-2) in the monomer mixture for obtaining the polymer as the component (A) is less than 44.5% by mass, the balance of the adhesive physical properties is lost and the adherend is adhered to. On the other hand, if it exceeds 94.5% by mass, light leakage may not be sufficiently suppressed. In order to sufficiently suppress light leakage and to obtain a pressure-sensitive adhesive layer excellent in durability, the content of component (a1-2) in the monomer mixture for obtaining a polymer as component (A) The amount is preferably 44.5 mass% or more and 94.5 mass% or less, more preferably 59.5 mass% or more and 90 mass% or less, and 69.5 mass% or more and 90 mass% or less. More preferably.

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

1.1.2. Component (a2) A hydroxyl group contained in component (a2) reacts with an isocyanate group in component (B) to form a crosslinked structure. Examples of the component (a2) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, and 2-hydroxy-3. -Hydroxyl group-containing (meth) acrylic acid ester monomers such as -chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxypropyl methacrylate Of these, one or a combination of two or more can be used. Especially, it is preferable that it is a C1-C6 hydroxyl-containing (meth) acrylic acid ester monomer.

1.1.3. (A3) Component The monomer mixture for obtaining the polymer as the component (A) is (a3) a reactive functional group other than one olefinic double bond and at least one hydroxyl group in the molecule. (Hereinafter sometimes simply referred to as “component (a3)”). In the present invention, the “reactive functional group” means a functional group capable of reacting with the component (B), and examples of the reactive functional group contained in the component (a3) include a carboxyl group, an amino group, and an amide group. And at least one group selected from acid anhydride groups.

  The reactive functional group contained in the component (a3) acts on the isocyanate group in the component (B) and the hydroxyl group in the component (a2), so that a crosslinked structure can be efficiently formed. Examples of the component (a3) include carboxyethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, acrylamide, N, N-dimethylaminopropyl acrylamide, Examples include diacetone acrylamide, acryloylmorpholine, acrylic acid, methacrylic acid, maleic acid, and itaconic acid. Among these, one kind or a combination of two or more kinds can be used. Of these, the component (a3) is more preferably at least one selected from acrylic acid and alkylamide, and more preferably acrylic acid, from the viewpoint of excellent efficiency for forming a crosslinked structure.

  In order to sufficiently suppress light leakage and to obtain a pressure-sensitive adhesive layer excellent in durability, the content of the component (a3) in the monomer mixture for obtaining the polymer as the component (A) is The content is preferably 0% by mass or more and 5% by mass or less, and more preferably 0.1% by mass or more and 2% by mass or less.

  In the pressure-sensitive adhesive composition according to the present embodiment, in the monomer mixture for obtaining the polymer as the component (A) from the viewpoint of more reliably achieving good adhesiveness and durability, and reduction of light leakage. The total amount of the component (a1), component (a2) and (a3) can be 90.1% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less.

1.1.4. Component (a4) The monomer mixture for obtaining the polymer as the component (A) is a monomer other than the components (a4) (a1) to (a3), and one monomer is included in the molecule. And a monomer having an olefinic double bond (hereinafter sometimes simply referred to as “component (a4)”). Examples of the component (a4) include vinyl monomers, styrene, acrylonitrile, macromonomers having a radical polymerizable vinyl group at the monomer terminal obtained by polymerizing a vinyl group. The content of the component (a4) in the monomer mixture for obtaining the polymer as the component (A) is preferably 0% by mass or more and 2% by mass or less.

1.1.5. Total amount of component (a1), (a2) and (a3) and (a4) In the pressure-sensitive adhesive composition according to this embodiment, good adhesiveness and durability, and reduction of light leakage can be achieved more reliably. The total amount of the components (a1), (a2), (a3) and (a4) in the monomer mixture for obtaining the polymer as the component (A) is 90.1% by mass or more and 100% by mass. More preferably, it is 95 mass% or more and 100 mass% or less, More preferably, it is 100 mass% or less.

  Furthermore, the pressure-sensitive adhesive composition according to this embodiment is a content of a monomer having an alkylene oxide group in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment can further reduce light leakage. Is preferably 5% by mass or less, and more preferably not containing a monomer having an alkylene oxide group. As a monomer which has an alkylene oxide group, the reactive emulsifier which has the (meth) acryl monomer which has an alkylene oxide group in a side chain, and an alkylene oxide group is mentioned, for example. In the present invention, “the pressure-sensitive 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 pressure-sensitive adhesive composition is 2% by mass or less. In particular, the content of the monomer having an alkylene oxide group in the pressure-sensitive adhesive composition is preferably 0% by mass or more and 2% by mass or less.

1.1.6. Tg
In the pressure-sensitive adhesive composition according to this embodiment, the Tg of the component (A) is −70 ° C. or higher and 0 ° C. or lower from the viewpoint of more reliably achieving good adhesiveness and durability and light leakage reduction. Preferably, it is -60 degreeC or more and -10 degreeC or less. In the present invention, the Tg of the component (A) is a value calculated by the following formula (6) (FOX formula).

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 component (A), and Tg _a1 , Tg _a2 , Tg _a3 , and Tg _a4 are the constituent monomers (a1), (a2), (a3), and The glass transition temperature (Tg (K)) of the homopolymer prepared from (a4) is shown, and W _a1 , W _a2 , W _a3 and W _a4 are each contained in the component (A), the constituent monomer (a1) , (A2), (a3), (a4) indicates the weight fraction.)

In addition, since Tg _A is calculated as an absolute temperature (K) by the above equation (6), it is converted to a Celsius temperature (° C.) as necessary.

  The glass transition temperatures of homopolymers prepared from typical monomers are shown in Table 1 below. More specifically, for example, Polymer Handbook Third Edition, Wiley-Interscience, 1999) It is described in.

1.1.7. Weight average molecular weight (Mw)
In addition, in the pressure-sensitive adhesive composition according to this embodiment, from the viewpoint of more reliably achieving good adhesion and durability and light leakage reduction, the component (A) has a weight average molecular weight (Mw) of 500,000 or more. It is preferably 2 million or less, and more preferably 800,000 to 1.8 million. Here, the weight average molecular weight of the component (A) is obtained by using GPC (gel permeation chromatography) and calculating the weight average molecular weight (Mw) in terms of standard polystyrene under the following conditions.
<GPC measurement conditions>
Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
GPC column configuration: The following five columns (all manufactured by Tosoh Corporation)
(1) TSK-GEL HXL-H (guard column)
(2) TSK-GEL G7000HXL
(3) TSK-GEL GMHXL
(4) TSK-GEL GMHXL
(5) TSK-GEL G2500HXL
Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm ³ Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 cm ³ / min Column temperature: 40 ° C.

  Moreover, it is preferable that (A) component concerning this embodiment exists in the range whose molecular weight distribution (weight average molecular weight / number average molecular weight) calculated | required by said GPC is 4-7. In the component (A), the molecular weight distribution of 7 or less means that the proportion of the high molecular weight component is high and the proportion of the low molecular weight component is smaller. Therefore, under the durability test conditions, the component (A) Since the cohesive force of the pressure-sensitive adhesive layer obtained by use can be maintained, it is preferable in that the durability of the pressure-sensitive adhesive layer can be further increased. In addition, in the component (A), since the molecular weight distribution is 4 or more, the component (A) becomes a polymer having a distribution with a certain degree of molecular weight, so that it is suitable for the pressure-sensitive adhesive composition containing the component (A). Stress relaxation can be provided.

1.2. Component (B) As described above, in the pressure-sensitive adhesive composition according to this embodiment, the crosslinking agent as component (B) is a crosslinking agent represented by the general formula (2) or the general formula (3). ,including.

In the pressure-sensitive adhesive composition according to this embodiment, from the viewpoint of imparting better adhesive strength and durability and more reliably preventing light leakage, the above general formula (2) or general formula (3) is used. In the group represented by the general formula (4) which is R ^1A , R ^1B , R ^1C included, x is more preferably an integer of 2 or more and 10 or less (more preferably an integer of 4 or more and 8 or less). , M is more preferably an integer of 1 to 10, more preferably an integer of 1 to 6. In the group represented by the general formula (5) which is R ^1A , R ^1B or R ^1C included in the general formula (2) or the general formula (3), y is an integer of 2 or more and 10 or less. More preferably, it is more preferably an integer of 4 to 8, and n is more preferably an integer of 1 or more and 10 or less, and further preferably an integer of 1 or less and 6 or less. Note that R ^1A , R ^1B , and R ^1C may be the same, different, or a plurality of combinations.

Examples of the alkylene group contained in R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F in the general formula (2) or the general formula (3) include It may be linear, branched, or cyclic, and is preferably linear. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group, an octylene group, a dodecylene group, a cyclohexylene group, and a cyclohexanedimethylene group. The alkylene group preferably has 2 or more and 10 or less carbon atoms, more preferably 4 or less and 8 or less. R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F themselves may each be an alkylene group. R ^2A , R ^2B and R ^2C may be the same or different. 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) is a skeleton derived from trimethylolpropane as represented by the general formula (2) or the general formula (3) ( - _(O-CH 2 -) with a _{3 -C-CH 2 CH 3)} , an isocyanate (-N = C = O) group.

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

  In the pressure-sensitive adhesive composition according to this embodiment, the molecular weight of the component (B) is preferably 500 or more and 10,000 or less, more preferably 2,000 or more, from the viewpoint of more reliably achieving cohesion and elasticity. More preferably, it is 7,000 or less.

  When the pressure-sensitive adhesive composition according to this embodiment contains the component (B), the group represented by the general formula (4) and / or the general formula (5) contained in the component (B) is represented. Due to the group containing the group, an appropriate cohesive force and elasticity are imparted to the pressure-sensitive adhesive composition. Accordingly, the pressure-sensitive adhesive composition can have both cohesive force and elasticity, which are often often in a trade-off relationship. Therefore, when the pressure-sensitive adhesive composition is used to form a pressure-sensitive adhesive layer of an image display device, light leakage can be prevented and adhesion and durability (wet heat durability) can be improved. .

  In general, when the pressure-sensitive adhesive composition is too hard (when the cohesive force of the pressure-sensitive adhesive composition is high and the elasticity is low), the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition may crack, On the other hand, when the pressure-sensitive adhesive composition is too soft (when the cohesive force of the pressure-sensitive adhesive composition is low and the elasticity is high), air bubbles enter the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition, which is preferable in terms of appearance. There may not be. On the other hand, since the pressure-sensitive adhesive composition according to the present embodiment contains the component (B), the pressure-sensitive adhesive composition has an appropriate cohesive force and elasticity, thereby preventing the pressure-sensitive adhesive layer from cracking, and Air bubbles can be prevented from entering the pressure-sensitive adhesive layer.

  The content of the component (B) in the pressure-sensitive adhesive composition according to the present embodiment is 100 masses of the component (A) according to the present embodiment from the viewpoint of preventing light leakage and enhancing the adhesive strength and durability. 0.05 parts by mass or more and 5 parts by mass or less, and preferably 0.1 parts by mass or more and 4 parts by mass or less with respect to parts.

  As the component (B), a commercially available crosslinking agent can be used. For example, as component (B), D-94 (distributor: Soken Chemical Co., Ltd.), E405-70B (distributor: Asahi Kasei Co., Ltd.), MFA-75B (distributor: Asahi Kasei Co., Ltd.) or the like may be used. it can.

  According to the pressure-sensitive adhesive composition for an optical film according to the present embodiment, by including the (B) crosslinking agent represented by the general formula (2) or the general formula (3), the general formula (2) or A crosslinking agent having no structure represented by the above general formula (3) (for example, NY730A (distributor: Mitsubishi Chemical Corporation), which is a commercially available isocyanate crosslinking agent, L-45 (distributor: Soken Chemical Co., Ltd.) ), Coronate HL (Distributor: Nippon Polyurethane Co., Ltd.), etc.), light leakage can be reduced more reliably and durability (wet heat durability) is excellent.

1.3. Other components The adhesive composition for optical films which concerns on this embodiment can further contain components other than (A) component and (B) component as needed. For example, the pressure-sensitive adhesive composition according to the present embodiment includes (C) a silane coupling agent (hereinafter sometimes simply referred to as “component (C)”), as long as the effects of the present invention are not impaired. (D) An ionic compound (hereinafter sometimes simply referred to as “component (D)”), an antioxidant, an ultraviolet absorber, a tackifier, a plasticizer, and the like may be blended.

1.3.1. (C) Silane coupling agent When the pressure-sensitive adhesive composition for an optical film according to this embodiment contains the component (C), the surface of the adherend is used with the pressure-sensitive adhesive composition for an optical film according to this embodiment. When the pressure-sensitive adhesive layer is formed, good adhesion with the adherend can be maintained. Component (C) is, for example, a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, or methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Silicon compounds having an epoxy structure such as methyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane And an amino group-containing silicon compound such as N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; and 3-chloropropyltrimethoxysilane; an oligomer type silane coupling agent, etc. Meta) Acrylic Copo Silane coupling agents having a functional group reactive with the functional group contained in the mer (A) is preferable because hardly cause peeling in wet heat environment.

  The content of the component (C) in the optical film pressure-sensitive adhesive composition according to the present embodiment is 0. 0 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of maintaining good adhesion to the adherend. It can be 01 parts by mass or more and 0.5 parts by mass or less, and preferably 0.05 parts by mass or more and 0.3 parts by mass or less.

1.3.2. (D) Ionic compound Moreover, the adhesive composition which concerns on this embodiment may contain the ionic compound (D). When the pressure-sensitive adhesive composition according to the present embodiment contains the component (D), when the pressure-sensitive adhesive layer is formed on the surface of the adherend using the pressure-sensitive adhesive composition according to the present embodiment, charging of the adherend is performed. Can be effectively prevented. Examples of the component (D) include an ionic compound that is composed of an anion and a cation and is liquid or solid at 25 ° C., specifically, an alkali metal salt, an ionic liquid (liquid at 25 ° C. Shape), surfactants and the like.

Examples of the alkali metal salt include compounds comprising an alkali metal cation such as lithium, sodium and potassium and an anion. Specifically, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, potassium chlorate , Potassium nitrate, sodium nitrate, sodium carbonate, sodium thiocyanate, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, sodium acetate, sodium alginate, sodium lignin sulfonate, sodium toluene sulfonate, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) IN, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) IN, Li (CF ₃ SO ₂ ) ₃ C, and the like. It is done.

As the cation constituting the ionic liquid, piperidinium cation, pyrrolidinium cation, cation having pyrroline skeleton, cation having pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyra Examples include an azolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, and a tetraalkylphosphonium cation, and examples of anions constituting the ionic liquid include Cl ⁻ , Br ⁻ , I ⁻ , AlCl _4. ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ (n = 2 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 can be mentioned.

  And as said ionic compound, it is comprised from these cations and anions, and a liquid ionic compound is mentioned at 25 degreeC. Specific examples of such ionic compounds include 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, and 1-ethyl. Carbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazole 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium dicyanamide, 1 Ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluoro Butyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis ( Trifluoromethanesulfonyl) 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 (trifluoromethanesulfonyl) imide, 1-methylpyrazolium tetrafluoroborate, 3- Methyl pyrazolium tetrafluoroborate, tetrahexylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium bis (penta Fluoroethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium trifluoromethane Sulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide, glycidyltrimethyl Ammonium bis (pentafluoroethanesulfonyl) imide, 1-butylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-3-methylimidazolium ( Trifluoromethanesulfonyl) trifluoroacetamide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) an Ni (trifluoromethanesulfonyl) trifluoroacetamide, diallyldimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, glycidyltrimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-dimethyl-N-ethyl-N-propylammonium bis ( Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-he Ptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) ) Imide, N, N-dimethyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N -Dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl- -Butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-pentyl-N-hexyl Ammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl- N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl -N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, triethylpropylammonium bis (trifluoromethanesulfonyl) imide, triethylpentylammonium bis (Trifluoromethanesulfonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl- N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluorome Tansulfonyl) imide, N, N-dipropyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N -Dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoro) Romethanesulfonyl) imide and the like.

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

  Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkylphenyls such as polyoxyethylene octylphenyl ether and polyoxyethylene nonielphenyl ether. Sorbitan higher fatty acid esters such as ethers, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene monolaurate, poly Polyoxyethylene higher fatty acid esters such as oxyethylene monostearate; for example, oleic acid monoglyceride, stearic acid monoglycera Glycerine higher fatty acid esters such as de, polyoxyethylene, polyoxypropylene, polyoxyalkylenes and their block copolymers such as polyoxyethylene butylene.

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

  Examples of the anionic surfactant include sodium laurate, sodium oleate, N-acyl-N-methylglycine sodium salt, carboxylate such as sodium polyoxyethylene lauryl ether carboxylate, sodium dodecylbenzenesulfonate, dialkylsulfosuccinate. Acid ester salts, sulfonates such as sodium dimethyl-5-sulfoisophthalate, sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate, sodium polyoxyethylene lauryl phosphate And phosphoric acid ester salts such as sodium polyoxyethylene nonylphenyl ether phosphate.

  Examples of the amphoteric surfactants include carboxybetaine surfactants, aminocarboxylates, imidazolinium petines, lecithins, and alkylamine oxides. In addition, conductive polymers, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, and the like can be used.

  Among these, an organic salt which is liquid at 25 ° C. is preferably used.

  Content of (D) component in the adhesive composition for optical films which concerns on this embodiment is 0.01 mass part or more and 3 mass parts or less with respect to 100 mass parts of (A) component which concerns on this embodiment. It is preferably 0.05 parts by mass or more and 2.5 parts by mass or less.

1.4. (A) Polymerization Method of Component (A) The polymerization method of component (A) is not particularly limited and can be polymerized by known methods such as solution polymerization, emulsion polymerization, suspension polymerization, etc. In producing the pressure-sensitive adhesive composition of the present invention using a mixture of coalesces, it is preferable to perform polymerization by solution polymerization from the viewpoint that the treatment process is relatively simple and can be performed in a short time.

  In solution polymerization, generally, a predetermined organic solvent, each monomer, a polymerization initiator, a chain transfer agent used as necessary, and the like are charged in a polymerization tank, under a nitrogen stream or a reflux temperature of the organic solvent, The reaction is carried out by heating for several hours with stirring.

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

  Among these organic solvents for polymerization, in the polymerization of the component (A), it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction, for example, esters and ketones. In view of solubility and ease of polymerization reaction, use of ethyl acetate, methyl ethyl ketone, acetone or the like is preferable.

  As the polymerization initiator, it is possible to use organic peroxides, azo compounds and the like that can be used in ordinary solution polymerization. Examples of such organic peroxides include tert-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, and di-2. -Ethylhexyl peroxydicarbonate, tert-butyl peroxybivalate, 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-tert- Amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-tert-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2 , 2-bis (4,4-di-te t-butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-tert-octylperoxycyclohexyl) butane and the like. Examples of the azo compound include 2,2′-azobis-isobuty Examples include rhonitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, and the like.

  Among these polymerization initiators, a polymerization initiator that does not cause a graft reaction during the polymerization reaction of the component (A) is preferable, and an azo polymerization initiator is particularly preferable. The amount used is usually 0.01 parts by weight or more and 2 parts by weight or less, preferably 0.1 parts by weight or more and 1.0 parts by weight or less, with respect to 100 parts by weight of the total amount of monomers.

  Further, in the production of the component (A) contained in the pressure-sensitive adhesive composition of the present invention, it is normal not to use a chain transfer agent, but as long as it does not impair the object and effect of the present invention. It is possible to use.

  Examples of such chain transfer agents include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; anthracene, phenanthrene, and fluorene. , Aromatic compounds such as 9-phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2, 3, Benzoquinone derivatives such as 5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, Bromotrichloromethane, tribromomethane, 3-chloro (B) Halogenated hydrocarbons such as -1-propene; Aldehydes such as chloral and furaldehyde: Alkyl mercaptans having 1 to 18 carbon atoms; Aromatic mercaptans such as thiophenol and toluene mercaptan; Mercaptoacetic acid and mercaptoacetic acid Examples thereof include alkyl esters having 1 to 10 carbon atoms; hydroxyalkyl mercaptans having 1 to 12 carbon atoms; and terpenes such as pinene and terpinolene.

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

1.5. Micro creep value Furthermore, in the pressure-sensitive adhesive composition according to this embodiment, from the viewpoint of more reliably preventing light leakage and further enhancing the adhesive force and durability, the pressure-sensitive adhesive composition according to this embodiment The micro creep value at 60 ° C. is preferably 0.50 mm or less, more preferably 0.35 mm or less when an 800 g load is applied for 1000 seconds. In the present invention, the minute creep value can be measured using the method described in Examples.

  As a result of suppressing the shrinkage of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition according to the present embodiment suppresses the shrinkage of the optical film provided with the pressure-sensitive adhesive layer. From the viewpoint of more reliably preventing light leakage, it is preferable that the difference between the micro creep value at 60 ° C. and the micro creep value at 23 ° C. is small. For example, the difference between the micro creep value at 60 ° C. and the micro creep value at 23 ° C. Is preferably within 0.30 mm.

1.6. Manufacture of an adhesive composition The adhesive composition which concerns on this embodiment is normally prepared by mixing the said (A) and (B) component and arbitrary components as needed simultaneously or in arbitrary orders. Moreover, when mixing (A) component and (B) component, when preparing (A) component by solution polymerization, (B) component is added to the solution containing (A) component after the completion of polymerization. In addition, when the component (A) is prepared by bulk polymerization, uniform mixing becomes difficult after the completion of the polymerization. Therefore, it is preferable to add and mix the component (B) during the polymerization.

1.7. Applications and operational effects The pressure-sensitive adhesive composition according to this embodiment can be suitably used as an adhesive for optical films (described in detail later). According to the pressure-sensitive adhesive composition according to the present embodiment, it exhibited excellent durability under high temperature and high humidity conditions, and was used for adhesion between an adherend such as a liquid crystal cell and an optical film such as a polarizing film. In this case, light leakage can be reduced. When the image display device includes a retardation film, since the retardation film is provided between the liquid crystal cell and the polarizing film, the pressure-sensitive adhesive composition according to this embodiment is provided between the retardation film and the polarizing film. An adhesive layer using can be provided.

  For example, when the pressure-sensitive adhesive composition according to this embodiment is used for adhesion between an adherend such as a liquid crystal cell and an optical film such as a polarizing film, it achieves good light leakage prevention characteristics and high durability. Therefore, high image quality of the image display device can be achieved. In this case, the pressure-sensitive adhesive composition according to the present embodiment can be used as an adhesive having a VA mode polarizing film, a TN mode polarizing film, or an IPS mode polarizing film as an adherend. Can be suitably used as an adhesive having a VA mode polarizing film or a TN mode polarizing film as an adherend.

  It is estimated that the light leakage prevention characteristic which is one effect of the adhesive composition which concerns on this embodiment is based on the following action mechanisms.

  That is, when a pressure-sensitive adhesive composition is provided on the surface of an optical film (polarizing film) using the pressure-sensitive adhesive composition according to this embodiment, the pressure-sensitive adhesive composition has the component (B), so that the component (B) The pressure-sensitive adhesive composition has a certain degree of hardness due to the group represented by the general formula (4) and / or the group containing the group represented by the general formula (5). , Moderate cohesive force and elasticity are imparted to the pressure-sensitive adhesive composition. Accordingly, the pressure-sensitive adhesive composition can have both cohesive force and elasticity, which are often often in a trade-off relationship. Therefore, when the pressure-sensitive adhesive composition is used to form a pressure-sensitive adhesive layer of an image display device, light leakage can be prevented and adhesion and durability (wet heat durability) can be improved.

2. Adhesive Optical Film An adhesive optical film according to another embodiment of the present invention is provided with an adhesive layer containing the optical film adhesive composition according to the above embodiment on one or both sides of the optical film. In producing the pressure-sensitive adhesive optical film according to the present embodiment, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition on the optical film with a gravure coater, Mayer bar coater, air knife coater, roll coater, or the like. It may be formed by drying and crosslinking the pressure-sensitive adhesive composition applied thereon at room temperature or by heating, or by forming a pressure-sensitive adhesive layer on a release film and transferring it to the optical film. Good. The thickness of the pressure-sensitive adhesive layer is usually 1 μm or more and 50 μm or less, preferably about 5 μm or more and 30 μm or less. In addition, in order to protect an adhesive layer before using an adhesive optical film, you may laminate | stack a peeling film on the surface of this adhesive layer.

  Examples of the pressure-sensitive adhesive optical film according to the present embodiment include those used in image display devices such as FPD, such as a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and the like. It can be an optical film selected from the group consisting of light diffusing films. The thickness of the optical film can be appropriately selected according to the purpose of use, but is usually from 10 μm to 500 μm, and preferably from about 15 μm to 300 μm.

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

3.1. (A) Preparation of Component A reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with a monomer mixture having the blending ratio shown in Table 2 below. The blending amount was 50% by mass. Next, 0.1 part by mass of azobisisobutyronitrile was added, stirred while replacing the air in the reaction vessel with nitrogen gas, and the temperature was raised to 60 ° C., followed by reaction for 8 hours. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain component (A) (acrylic polymers A to G).

3.2. Preparation of adhesive processing polarizing plate for evaluation Above 3.1. Using the component (A) obtained in the above, the respective components were added in the formulations shown in Tables 3 and 4 (solid content formulation) below, and pressure-sensitive adhesive compositions of Examples 1 to 15 and Comparative Examples 1 to 11 Solution was obtained. The pressure-sensitive adhesive composition solution was applied to the surface of the peeled polyester film and dried to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 20 μm. After sticking this pressure-sensitive adhesive sheet on one side of the polarizing film for VA mode, it was aged in a dark place at 23 ° C./50% RH for 7 days to obtain a pressure-sensitive adhesive processed polarizing plate for evaluation. As the component (B), as shown in Tables 3 and 4 below, crosslinking agents 1 to 6 were used. Each of the crosslinking agents 1 to 6 has a structure represented by the following structural formulas (7) to (12). The weight average molecular weight (MW) of the crosslinking agent 1 is about 3,700, the weight average molecular weight (MW) of the crosslinking agent 2 is about 4,000, and the weight average molecular weight (MW) of the crosslinking agent 3 is about 4,000.

・・・（７）
（式中、ｌは１以上１０以下であり、ｍは１以上１０以下であり、ｎは１以上１０以下であり、ａは１以上１０以下であり、ｂは１以上１０以下であり、ｃは１以上１０以下である。）[Crosslinking agent 1]

... (7)
(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, c Is 1 or more and 10 or less.)

・・・（８）
（式中、ｌは１以上１０以下であり、ｍは１以上１０以下であり、ｎは１以上１０以下である。）[Crosslinking agent 2]

... (8)
(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.)

・・・（９）
（式中、ｌは１以上１０以下であり、ｍは１以上１０以下であり、ｎは１以上１０以下である。）[Crosslinking agent 3]

... (9)
(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.)

・・・（１０）[Crosslinking agent 4]

... (10)

・・・（１１）[Crosslinking agent 5]

(11)

・・・（１２）[Crosslinking agent 6]

(12)

  For each evaluation adhesive polarizing plate, maximum deformation rate, strain recovery rate, light leakage (LED using light source: LED method) and light leakage (without using LED as light source) shown in Table 3 and Table 4 below : Non-LED method) and wet heat durability (foaming and tearing) were evaluated by the following methods.

3.3. Evaluation method 3.3.1. Light leakage 19-inch size VA liquid crystal panel (I / O Data Co., Ltd., model: removed from LCD-A191EW), and peeled polyester film peeled off for evaluation. The layers were bonded so that the layer was in contact with the liquid crystal panel and the evaluation pressure-sensitive adhesive-processed polarizing plate was crossed Nicol, and allowed to stand in an atmosphere at 80 ° C. for 240 hours, and then in an atmosphere at 23 ° C./50% RH. And left for 2 hours. Thereafter, the liquid crystal panel on which the polarizing plate was bonded was connected to a personal computer in a dark room to display a full screen black. In this test, evaluation was performed using two types of liquid crystal panels: a VA liquid crystal panel and a TN liquid crystal panel. As shown in FIG. 1, this full-screen black display monitor has a luminance (La, Lb, Lc, Ld) in a 1 cm diameter area near each corner and a luminance (Lcenter) in a 1 cm diameter area in the center of the monitor. ) Was measured using a luminance meter (manufactured by Highland, model name: RISA-COLOR / CD8), and light leakage (ΔL) was calculated based on the following formula (13). Smaller ΔL means less light leakage (from the backlight). Usually, if ΔL is less than 2.0, it can be used as a liquid crystal display panel.
ΔL = (La + Lb + Lc + Ld) / 4−Lcenter (13)

  As for the VA liquid crystal panel, as shown by a dotted line in FIG. 1, the range (R) where light leakage occurred near the corner of the display monitor is visually measured. For the TN liquid crystal panel, As shown by the dotted line in FIG. 2, the range (R) where light leakage occurred near the outer periphery of the display monitor was measured visually. The smaller the area where light leakage occurs, the smaller the light leakage. Normally, if R is less than 20 mm, it can be used as a liquid crystal display panel. More preferably, it is less than 16.5.

3.3.2. Minute creep value Each pressure-sensitive adhesive polarizing plate for evaluation was cut into a width of 10 mm and a length of 100 mm, and each pressure-sensitive adhesive polarizing plate for evaluation obtained by peeling off the peeled polyester film was in contact with glass and 100 mm ^2. The layers were bonded so as to have a bonding area of (10 mm × 10 mm), autoclaved (50 ° C., 5 atm), and then allowed to stand in a 23 ° C./50% RH atmosphere for 24 hours. This was used as a sample for a micro creep test. A test sample was set at a length of 15 mm of the fixing chuck portion in the chamber BOX of a micro creep measuring machine (manufactured by Eiko Seiki Co., Ltd., model name: TA.TX.PLUS). When the upper and lower sides of the test material were fixed and an 800 g load was applied in the vertical direction for 1000 seconds, the distance at which the bonded end of the sample and the adherend shifted from the initial value was measured.

3.3.3. Wet heat durability The adhesive processing polarizing plate for evaluation which peeled off the peeled polyester film was cut into a 15 inch size (233 mm × 309 mm), and an adhesive layer was formed on one surface of a non-alkali glass plate having a thickness of 0.5 mm. It stuck using the laminator roll so that the said glass plate might be touched. After pasting, a test plate was obtained by pressurizing in an autoclave (manufactured by Kurihara Seisakusho) under conditions of 0.5 MPa, 50 ° C., and 20 minutes. The test plate thus obtained was left under conditions of 60 ° C./90% RH for 500 hours. After completion of the test, the test plate is taken out from the test environment and left to stand for 2 hours in a 23 ° C./50% RH atmosphere, and then visually observed for foaming (cohesion insufficient) and tearing (overcrosslinking) in the adhesive layer. The wet heat durability was evaluated according to the following evaluation criteria.

(Foam-size)
○: No foaming is observed Δ: Foam diameter is 1 mm or less ×: Foam diameter is greater than 1 mm

(Foaming-generation amount)
○: No foaming is observed Δ: The number of foams is 10 or less ×: The number of foams is more than 10

(Tear-size)
○: No tearing is observed Δ: The area where tearing occurs is less than 5% with respect to the entire bonding part (100%) in the test plate x: The area where tearing occurs is the entire bonding part in the test plate (100%) over 5%

(Rear-position)
○: No tearing Δ: There is a defect only in the 1 cm width region near each end of the test plate ×: There is a defect outside the region and 1 cm region near each end of the test plate

In addition, the abbreviation in Table 2 has the following meaning.
AA: acrylic acid BA: n-butyl acrylate t-BA: tert- (tertiary) butyl acrylate 4-HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate L-45: TDI isocyanate compound (Soken Chemical Co., Ltd.) L-45)
MA: Methyl acrylate KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
Ionic compound (component (D): antistatic agent): 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide

  From the results of Tables 3 and 4, the compositions of Examples 1 to 15 described above contain the crosslinking agents 1 to 3 represented by the general formula (2) or the general formula (3) as the component (B). Thus, high adhesive strength and excellent durability can be realized, and light leakage can be reduced. 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 used crosslinking agent). 4 to 6 do not have the structure represented by the above general formula (2) or the above general formula (3)) (Comparative Examples 1 to 11), and the light leakage could not be sufficiently reduced. Can understand.

[Explanation of symbols]
100 Image display device (liquid crystal panel)
La, Lb, Lc, Ld Luminance near the corner of the image display device Lcenter Luminance at the center of the image display device

Claims (7)

(A) (a1) a (meth) acrylate monomer represented by the following general formula (1) and (a2) a monomer having one olefinic double bond and at least one hydroxyl group in the molecule An acrylic polymer that is a polymer of a monomer mixture containing a monomer;
(B) a crosslinking agent represented by the following general formula (2) or the following general formula (3);
(C) only contains a silane coupling agent, the,
The molecular weight distribution of the (A) acrylic polymer is 4 or more and 7 or less,
(B) the crosslinking agent (B) is included in an amount of 0.05 parts by weight to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer (A),
(A) The silane coupling agent is contained in an amount of 0.01 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the acrylic polymer.
An adhesive composition for optical films.

(1)
(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 1 to 14 carbon atoms.)

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

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

.... (4)
(In the formula, x is an integer of 2 to 10, and m is an integer of 1 to 10.)

(5)
(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 monomer mixture includes (a1) 90% by mass or more and 99.9% by mass or less of the (meth) acrylic acid ester monomer represented by the general formula (1) and one in the molecule (a2). The pressure-sensitive adhesive composition for an optical film according to claim 1 , comprising 0.1% by mass or more and 10% by mass or less of a monomer having an olefinic double bond and at least one hydroxyl group. The monomer mixture has a glass transition temperature when (a1-1) a homopolymer is formed as the (a1) (meth) acrylate monomer represented by the general formula (1). (Tg) is 0 ° C. or higher, and the (meth) acrylic acid ester monomer represented by the general formula (1) is 5% by mass to 55% by mass and (a1-2) a homopolymer is formed. Assuming that the glass transition temperature (Tg) is less than 0 ° C., the (meth) acrylic acid ester monomer represented by the general formula (1) is 44.5% by mass or more and 94.5% by mass or less, (Here, the total amount of said (a1) and said (a2) is 90.1 mass% or more and 100 mass% or less), The adhesive composition for optical films of Claim 2 characterized by the above-mentioned. The pressure-sensitive adhesive for an optical film according to any one of claims 1 to 3 , further comprising 0.01 to 3 parts by mass of (D) an ionic compound with respect to 100 parts by mass of the (A) acrylic polymer. Composition.   The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 4, wherein a micro creep value at 60 ° C is 0.50 mm or less. An adhesive layer comprising an adhesive composition for optical films according to any one of claims 1 to 5, instal on one or both sides of the optical film, adhesive optical film. The pressure-sensitive adhesive optical film according to claim 6 , which is an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptical polarizing film, an antireflection film, a brightness enhancement film, and a light diffusion film.

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