JP2020090586A - Adhesive for optical film, adhesive layer, optical member and image display device - Google Patents

Abstract

To provide an adhesive for an optical film, which gives improved durability in a severe environment (such as high temperature, high humidity and heat shock) even when used for a single-side protected polarizing plate, which can suppress both of warpage and dent, and which has excellent reworkability (processability).SOLUTION: The adhesive for an optical film contains a (meth)acrylate copolymer (A), in which the (meth)acrylate copolymer (A) comprises 10 mass% or more and 95 mass% or less of a structural unit derived from (a1) an alkyl(meth)acrylate monomer, 5 mass% or more and 90 mass% or less of a structural unit derived from (a2) an alkyl(meth)acrylate monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group, and more than 0 mass% and 20 mass% or less of a structural unit derived from (a3) a functional group-containing monomer that is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group, where the total amount of structural units derived from above (a1), (a2) and (a3) is set to 100 mass%. The (meth)acrylate copolymer (A) has a glass transition temperature of over -55°C and -50°C or lower, and a weight average molecular weight of 700000 or more and 2000000 or less.SELECTED DRAWING: None

Description

The present invention relates to an adhesive for optical films. The present invention also relates to a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive for an optical film, an optical member using the pressure-sensitive adhesive layer, and an image display device using the optical member.

Currently, flat display panels such as liquid crystal display panels (LCD) and plasma display panels (PDP) are mainly used as display panels. On the surface of the flat display panel, a laminated body in which a plurality of films are laminated is usually stuck. For example, an LCD usually has an optical film such as a polarizing plate, a retardation film, a viewing angle widening film, and a brightness improving film laminated on the surface of a liquid crystal panel. And each layer which comprises a flat display panel is usually stuck by the adhesive layer formed by various adhesives.

On the other hand, recently, there is a demand for a cheaper and thinner polarizing plate. As one form, a single-sided protective polarizing plate (single-sided protective polarizing plate) in which only one protective film is used on one side of a polarizer, compared to a double-sided protective polarizing plate (double-sided protective polarizing film) in which both sides of a conventional polarizer are bonded A protective polarizing film) has been proposed. However, it has been known that this one-sided protective polarizing plate, unlike the conventional two-sided protective polarizing plate, greatly contracts in durability, particularly in heating durability and heat shock cycle test.

Therefore, this single-sided protective polarizing plate is required to have the same durability as the conventional double-sided protective polarizing plate. For this reason, it is required to suppress the occurrence of peeling and floating, and further to suppress the bubbles generated at the ends of the polarizing plate due to the large shrinkage of the polarizing plate during the durability test.

Further, since the panel is apt to warp due to the large shrinkage during the durability test, it is also required to control such warpage and dents generated in the pressure-sensitive adhesive layer at the same time.

As a pressure-sensitive adhesive used in a conventional double-sided protective polarizing plate, for example, Patent Documents 1 to 4 propose a pressure-sensitive adhesive containing a copolymer having a glass transition temperature in the range of -47.4°C to -20°C. Has been done. Further, Patent Documents 5 to 7 propose pressure-sensitive adhesives for polarizing plates containing a copolymer having a glass transition temperature of −55° C. or lower.

JP, 2009-084541, A JP, 2009-108113, A JP, 2009-2807776, A JP-A-2007-238853 JP, 2004-224873, A JP, 2003-193013, A JP, 2003-193014, A

However, according to the study by the present inventor, it has been found that there are the following problems. When the pressure-sensitive adhesives described in Patent Documents 1 to 7 are used for a single-sided protective polarizing plate, durability under a harsh environment (high temperature, high humidity, heat shock) (particularly of bubbles generated at the end of the polarizing plate) It was found that there is a phenomenon in which the suppression and the suppression of peeling of the polarizing plate) decrease. Furthermore, it has been found that there is a phenomenon that warpage and dents are likely to occur. In addition, it has also been found that there is a problem that reworkability (workability) is not sufficient.

The present invention has been made in view of the above circumstances. That is, even when used for a single-sided protective polarizing plate, it has durability in a harsh environment (high temperature, high humidity, heat shock) (in particular, suppression of bubbles generated at the end of the polarizing plate and peeling of the polarizing plate). It is an object of the present invention to provide a pressure-sensitive adhesive for an optical film, which is capable of suppressing both warpage and dents and is excellent in reworkability (workability).

The present inventor has conducted diligent research in order to solve the above problems. As a result, they have found that an adhesive containing a (meth)acrylic acid ester copolymer having a specific structure can solve the above problems, and completed the present invention.

That is, the present invention is a pressure-sensitive adhesive for an optical film, comprising the (meth)acrylic acid ester copolymer (A), wherein the (meth)acrylic acid ester copolymer (A) is (a1)(meth). ) Structural unit derived from alkyl acrylate monomer of acrylic acid 10% by mass or more and 95% by mass or less; (a2) Structural unit derived from alkyl ester of (meth)acrylic acid alkyl ester monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group 5% by mass or more 90 % Or less; (a3) a structural unit derived from a functional group-containing monomer which is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group: more than 0% by mass and 20% by mass or less; (however, (a1) , (A2), and the total amount of structural units derived from (a3) is 100% by mass, and the glass transition temperature of the (meth)acrylic acid ester copolymer (A) exceeds −55° C. and −50° C. The following is the pressure-sensitive adhesive for an optical film, wherein the (meth)acrylic acid ester copolymer (A) has a weight average molecular weight of 700,000 to 2,000,000.

According to the present invention, even when used in a single-sided protective polarizing plate, durability under a harsh environment (high temperature, high humidity, heat shock) (in particular, suppression of bubbles generated at the end of the polarizing plate, and Provided is a pressure-sensitive adhesive for an optical film, which can improve peeling of a polarizing plate). Further, it is possible to provide a pressure-sensitive adhesive for an optical film, which is capable of suppressing both warpage and dents and has excellent reworkability (workability).

Hereinafter, modes for carrying out the present invention will be described.

[Adhesive for optical film]
The pressure-sensitive adhesive for optical films of the present invention contains a (meth)acrylic acid ester copolymer (A), and the (meth)acrylic acid ester copolymer (A) is (a1) (meth)acrylic acid alkyl ester. Constituent unit derived from monomer 10% by mass or more and 95% by mass or less; (a2) Constituent unit derived from (meth)acrylic acid alkyl ester monomer having alkoxyalkyl group or alkoxyalkylene glycol group 5% by mass or more and 90% by mass or less; (A3) A structural unit derived from a functional group-containing monomer that is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group: more than 0% by mass and 20% by mass or less; (however, (a1), (a2), And the total amount of (a3) is 100% by mass, and the glass transition temperature of the (meth)acrylic acid ester copolymer (A) is higher than −55° C. and −50° C. or lower. The weight average molecular weight of the acid ester copolymer (A) is 700,000 or more and 2,000,000 or less.

According to the pressure-sensitive adhesive for an optical film of the present invention having such a constitution, even when used in a single-sided protective polarizing plate, durability under a harsh environment (high temperature, high humidity, heat shock) (particularly, Suppression of bubbles generated at the end of the polarizing plate and suppression of peeling of the polarizing plate) can be improved. Furthermore, both warpage and dents can be suppressed, and reworkability (workability) is also excellent.

Recently, there has been a demand for cheaper and thinner polarizing plates. As one form thereof, a single-sided protective polarizing plate using only one protective film on one side of a polarizer has been proposed. In the one-sided protective polarizing plate, the force of suppressing the shrinkage of the polarizer by the protective film is reduced. Therefore, the present inventor has found that shrinkage due to heating or the like is likely to occur, and in particular, a problem that bubbles are likely to occur at the end of the polarizing plate occurs. Therefore, the present inventor has conducted earnest studies to solve this problem. As a result, the glass transition temperature is lower than that of a conventional copolymer (more than −55° C. and −50° C.) and the weight average molecular weight is 700,000 or more and 2,000,000 or less (meth)acrylic acid ester copolymer ( It was found that the above problems can be solved by using an adhesive containing A). By using a (meth)acrylic acid ester copolymer having a low glass transition temperature, it is possible to follow a polarizing plate that has shrunk due to heating or the like, and it is possible to suppress the generation of bubbles at the ends. In order to suppress the air bubbles at the ends, it is advantageous that the glass transition temperature of the (meth)acrylic acid ester copolymer is low. However, when the glass transition temperature of the (meth)acrylic acid ester copolymer becomes low, the durability also deteriorates and it becomes impossible to suppress dents. Therefore, by setting the weight average molecular weight of the (meth)acrylic acid ester copolymer (A) within a specific range (700,000 or more and 2,000,000 or less), durability in a harsh environment (high temperature, high humidity, heat shock) It has been found that the properties (particularly, suppression of bubbles generated at the ends of the polarizing plate and suppression of peeling of the polarizing plate) can be improved. Furthermore, they have found that it is possible to obtain a pressure-sensitive adhesive that can suppress both warpage and dents and that is also excellent in reworkability (workability).

The above mechanism is speculative and the present invention is not limited to the above mechanism.

Hereinafter, each component constituting the pressure-sensitive adhesive for an optical film according to the present invention will be described in order.

In addition, in this specification, "(meth)acrylic acid ester" is a general term for acrylic acid ester and methacrylic acid ester. Similarly, a compound containing (meth) such as (meth)acrylamide is a generic term for a compound having “meth” in the name and a compound not having “meth”. Further, the "(meth)acrylic acid ester copolymer (A)" is also simply referred to as "copolymer (A)".

<(Meth)acrylic acid ester copolymer (A)>
The pressure-sensitive adhesive for optical films according to the present invention essentially contains the (meth)acrylic acid ester copolymer (A).

The weight average molecular weight (Mw) of the copolymer (A) according to the present invention by gel permeation chromatography (GPC) is 700,000 or more and 2,000,000 or less. When the weight average molecular weight (Mw) is less than 700,000, dents are generated and durability at high temperature and reworkability after heating are deteriorated. On the other hand, when it exceeds 2 million, warpage occurs.

The weight average molecular weight (Mw) of the copolymer (A) by gel permeation chromatography (GPC) is 900,000 from the viewpoint of further improving the durability in a harsh environment (high temperature, high humidity, heat shock). It is preferably at least 2 million. The weight average molecular weight is more preferably more than 1 million and 2,000,000 or less. The weight average molecular weight (Mw) of the copolymer (A) of the present invention can be easily controlled by those skilled in the art as follows. That is, it can be easily controlled by appropriately adjusting the reaction conditions such as the type and/or the amount of the polymerization initiator used in the polymerization reaction described later, the reaction temperature, the reaction time, and the like.

The weight average molecular weight (Mw) of the copolymer (A) can be measured by gel permeation chromatography (GPC). Specifically, it can be measured by the method shown in the examples.

Further, the (meth)acrylic acid ester copolymer (A) according to the present invention has a glass transition temperature of higher than −55° C. and −50° C. or lower. When the glass transition temperature is −55° C. or lower, dents are likely to occur. On the other hand, when the glass transition temperature exceeds −50° C., end bubbles are likely to be generated in a harsh environment (high temperature, high humidity, heat shock). The upper limit of the glass transition temperature of the copolymer (A) is preferably −51° C. or lower, and more preferably −52° C. or lower.

In the present specification, the glass transition temperature of the (meth)acrylic acid ester copolymer (A) is calculated from the glass transition temperature of the homopolymer of the monomers constituting the polymer and the content ratio thereof by the Fox equation. It is a theoretical value.

Fox's formula: 1/Tg=(w1/Tg1)+(w2/Tg2)+...+(wn/Tgn)
Tg: Glass transition temperature (K) of polymer
Tgn, Tg2,... Tgn: glass transition temperature (K) of homopolymer of each monomer
w1, w2,... Wn: Weight fraction of each monomer The theoretical value of the glass transition temperature obtained from the Fox equation is the actually measured glass transition obtained by differential scanning calorimetry (DSC) or dynamic viscoelasticity. It matches well with the temperature.

The glass transition temperature of the copolymer (A) can be easily controlled by appropriately adjusting the types and amounts of the monomers (particularly (a1) and (a2)) used and the weight average molecular weight of the copolymer (A). can do.

In the present invention, the constitutional unit constituting the copolymer (A) is
(A1) Structural unit derived from (meth)acrylic acid alkyl ester monomer (hereinafter, also simply referred to as “component (a1)”) 10% by mass or more and 95% by mass or less,
(A2) a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group (hereinafter, also simply referred to as “component (a2)”) 5 mass% or more and 90 mass% or less,
(A3) Structural unit derived from a functional group-containing monomer that is a (meth)acrylic acid derivative monomer having one radical-polymerizable functional group (hereinafter also simply referred to as "component (a3)"): more than 0% by mass and 20% by mass or less When,
(However, the total amount of (a1), (a2), and (a3) is 100% by mass)
including.

In the present specification, for example, “the copolymer X contains a structural unit derived from the monomer Y _{1 and} a structural unit derived from the monomer Y ₂ ”is a raw material used when the copolymer X is obtained by copolymerization. It means that the monomer includes a monomer Y ₁ and a monomer Y ₂ .

Hereinafter, the structural units derived from the respective monomers that can form the copolymer (A) according to the present invention will be described in order.

[(A1) Structural unit derived from (meth)acrylic acid alkyl ester monomer]
The copolymer (A) according to the present invention includes (a1) a structural unit derived from an alkyl (meth)acrylate monomer. It is considered that such a component (a1) has the meaning of ensuring adhesiveness and basic properties by being included as a constituent unit of the (meth)acrylic acid ester copolymer (A) according to the present invention. ..

In the present invention, the structure of the (meth)acrylic acid alkyl ester monomer is not particularly limited as long as the alkyl group is introduced into the ester portion of the monomer. However, the (meth)acrylic acid alkyl ester monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group is classified as the component (a2).

The carbon number of the alkyl group is not particularly limited, but is preferably 1 or more and 18 or less. Further, the carbon number of the alkyl group is more preferably 2 or more and 18 or less from the viewpoint of the glass transition temperature of the copolymer (A) and the compatibility when used in combination with the crosslinking agent (B) described below. The carbon number is more preferably 3 or more and 16 or less, and particularly preferably 4 or more and 12 or less. Further, the alkyl group may be linear, branched or cyclic. From the viewpoint of lowering the glass transition temperature of the copolymer (A), it is preferably linear or branched. When the alkyl group is cyclic, it has 3 or more carbon atoms.

The alkyl group is not particularly limited, but is not limited to methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, isobutyl group, n-pentyl group, isopentyl group, n. -Hexyl group, 2-hexyl group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, t-heptyl group, isoheptyl group, t-heptyl group, n-octyl group , Isooctyl group, t-octyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, cyclohexyl group, etc. Can be mentioned. In particular, a methyl group, an n-butyl group, an n-hexyl group, a 2-ethylhexyl group, a nonyl group, and an isononyl group are preferable from the viewpoint of securing adhesiveness and securing basic properties.

Therefore, specific examples of the (meth)acrylic acid alkyl ester monomer include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl( (Meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth) Acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate and the like can be mentioned. Among them, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferable from the viewpoint of improvement in heating durability and adhesive strength (particularly reworkability). The component (a1) can be used alone or in combination of two or more. As the component (a1), a commercially available product or a synthetic product may be used. Examples of commercially available products include 2EHA, BA (above, manufactured by Nippon Shokubai Co., Ltd.) and the like.

The content of the structural unit derived from the component (a1) in the copolymer (A) according to the present invention (the blending amount of the (meth)acrylic acid ester monomer as a raw material monomer) is the same as that of the component (a1), the component (a2), And the total amount of the constituent units derived from the component (a3) is 100% by mass or more and 90% by mass or less. When the content of the component (a1) is less than 10% by mass, the proportion of the components other than (a1) in the copolymer (A) increases. This makes it difficult to balance the suppression of air bubbles at the ends, the adhesiveness, the durability, and the suppression of warpage and dents. On the other hand, when the content exceeds 90 mass, it becomes difficult to impart cohesive force to the pressure-sensitive adhesive, and the adhesiveness decreases.

The content of the structural unit derived from the component (a1) is 13% by mass or more and 88% by mass or less, with the total amount of the structural units derived from the component (a1), the component (a2), and the component (a3) being 100% by mass. Preferably. The content is more preferably 15% by mass or more and 80% by mass or less, and further preferably 50% by mass or more and 79% by mass or less.

[(A2) Structural unit derived from (meth)acrylic acid alkyl ester monomer having alkoxyalkyl group or alkoxyalkylene glycol group]
The (meth)acrylic acid ester copolymer (A) of the present invention contains a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group.

When the monomer constituting the (meth)acrylic acid ester copolymer (A) corresponds to both the component (a1) component and the component (a2), it shall be classified as the component (a2).

The component (a2) is not particularly limited as long as it has an alkoxyalkyl group or an alkoxyalkylene glycol structure in the (meth)acrylic acid ester molecule. It is considered that when such a component is contained in the pressure-sensitive adhesive of the present invention, it has an effect of improving adhesiveness and durability. Further, by including the structural unit derived from the component (a2), it becomes easier to control the glass transition temperature within the range of the present invention, and it is possible to suppress edge bubbles.

The carbon number of the alkoxy moiety in the alkoxyalkyl group or the alkoxyalkylene glycol group is not particularly limited. However, it is preferably 1 or more and 20 or less from the viewpoint of a balance between improvement in adhesiveness and improvement in durability, and further from the viewpoint of suppressing edge bubbles. The carbon number is more preferably 2 or more and 18 or less, still more preferably 2 or more and 10 or less.

Further, the carbon number of the alkyl portion in the alkoxyalkyl group is not particularly limited. However, from the viewpoint of a balance between improvement of adhesiveness and improvement of durability, and further suppression of air bubbles at the ends, it is preferably 1 or more and 6 or less, and more preferably 1 or more and 4 or less.

The carbon number of the alkylene portion in the alkoxyalkylene glycol group is not particularly limited. However, the carbon number is preferably 1 or more and 4 or more, and more preferably 1 or more and 3 or less from the viewpoint of the balance between the improvement of the adhesiveness and the improvement of the durability and the suppression of the bubbles at the end.

The component (a2) is preferably a compound represented by the following chemical formula 1.

In Chemical Formula 1, R ₁₁ is a hydrogen atom or a methyl group, and R ₁₂ is an alkoxyalkyl group or —(A—O) _n —X.

Preferred alkoxyalkyl groups include methoxymethyl group, ethoxymethyl group, methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, methoxypropyl group, ethoxypropyl group, methoxybutyl group, ethoxybutyl group. .. More preferred alkoxyalkyl groups include ethoxymethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, ethoxypropyl group, ethoxybutyl group.

The above A is an alkylene group having 1 to 4 carbon atoms, and examples thereof include a methylene group, an ethylene group, a trimethylene group, a propylene group, or a butylene group. The above n is 1 or more and 10 or less, preferably 1 or more and 4 or less.

The X is an alkyl group having 1 to 20 carbon atoms. Such an alkyl group may be linear or branched. The carbon number is preferably 2 or more and 18 or less, more preferably 2 or more and 10 or less. Examples of such an alkyl group are the same as the alkyl groups mentioned in the description of the above component (a1), but an ethyl group or a propyl group is particularly preferable.

Specific examples of the component (a2) include methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxypropyl (meth). Acrylate, methoxybutyl (meth)acrylate; ethoxy-diethylene glycol (meth)acrylate, ethoxy-triethylene glycol (meth)acrylate, methoxy-triethylene glycol (meth)acrylate, methoxy-diethylene glycol (meth)acrylate, propoxy-diethylene glycol (meth ) Acrylate, methoxy-triethylene glycol (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate (2-ethylhexyloxy-diethylene glycol (meth)acrylate), methoxy-polyethylene glycol (meth)acrylate (n=4 or more 10) The following), methoxydipropylene glycol (meth)acrylate and the like.

Among them, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxy are particularly preferable from the viewpoint of a balance between improvement of adhesiveness and improvement of durability, and further suppression of end air bubbles. Ethyl (meth)acrylate, ethoxy-diethylene glycol (meth)acrylate and 2-ethylhexyl-diglycol (meth)acrylate are more preferable.

The component (a2) can be used alone or in combination of two or more. As the component (a2), a commercially available product or a synthetic product may be used. Examples of commercially available products include Light Acrylate EC-A, Light Acrylate EHDG-AT (above, Kyoeisha Chemical Co., Ltd.), Viscoat #190 (Osaka Organic Chemical Co., Ltd.) and the like.

The content of the structural unit derived from the component (a2) in the copolymer (A) is 5 mass when the total amount of the structural units derived from the components (a1), (a2), and (a3) is 100 mass %. % To 90% by mass. If the content is less than 5% by mass, the glass transition temperature (Tg) will be high, and air bubbles will be generated at the edges. On the other hand, when it exceeds 90% by mass, Tg tends to be too low, resulting in peeling or marked deterioration in dent resistance. The content of the structural unit derived from the component (a2) is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[(A3) Structural unit derived from functional group-containing monomer that is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group]
In a preferred embodiment of the present invention, the (meth)acrylic acid ester copolymer (A) contains a structural unit derived from a functional group-containing monomer which is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group. ..

Here, the "(meth)acrylic acid derivative" refers to a compound obtained from (meth)acrylic acid as a starting material. Preferred is (meth)acrylic acid ester or (meth)acrylamide.

That is, the component (a3) may be a (meth)acrylic acid ester monomer or a (meth)acrylamide monomer having a (meth)acryloyl group and one or more functional groups other than the (meth)acryloyl group. preferable.

Although the component (a3) is an optional component, by combining it with the above components (a1) and (a2) and being contained in the adhesive of the present invention, the intended effect of the present invention can be more efficiently achieved. it can.

The component (a3) is highly reactive with the crosslinking agent (B). Therefore, it is considered to have the significance of improving the cohesiveness and heat resistance of the pressure-sensitive adhesive layer by being included as a constitutional unit of the copolymer (A) according to the present invention. In addition, the crosslinking density of the pressure-sensitive adhesive layer increases, the pressure-sensitive adhesive layer becomes hard, and the amount of deformation of the pressure-sensitive adhesive layer at the time of re-peeling becomes small. As a result, the adhesive force is reduced, desirable reworkability is obtained, peeling can be suppressed in terms of durability, and further warpage and dents can be suppressed.

In addition, when the monomer which comprises a (meth)acrylic acid ester copolymer (A) corresponds to both a component (a1) component and a component (a3), it shall classify as a component (a3).

The functional group contained in the component (a3) is preferably a functional group that reacts with the crosslinking agent when the crosslinking agent (B) is used. The functional group is preferably a hydroxy group, an acyl group or an epoxy group, more preferably a hydroxy group. By including the copolymer (A) obtained by using the monomer having such a functional group in the pressure-sensitive adhesive, the copolymer (A) is cross-linked with the cross-linking agent (B), and the durability at high temperature is high. Is expected to improve. That is, a preferable mode of the present invention is that (a3) the functional group-containing monomer, which is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group, has a hydroxy group, an acyl group or an epoxy group (meth)acrylic An adhesive for optical films, which is an acid ester monomer or a (meth)acrylamide monomer. A more preferable form of the present invention is a form in which the copolymer (A) has a hydroxy group.

Hereinafter, the (meth)acrylic acid ester monomer and (meth)acrylamide monomer having a hydroxy group, an acyl group or an epoxy group will be described.

<<(a3-1) (meth)acrylic acid ester monomer having a hydroxy group, an acyl group or an epoxy group>>
The (meth)acrylic acid ester monomer having a hydroxy group, an acyl group or an epoxy group (hereinafter, also referred to as the component (a3-1)) typically has a structure represented by the following chemical formula 2.

In the above chemical formula 2,
R ₄ is a hydrogen atom or a methyl group,
R ₅ is a single bond or a divalent organic group,
R ₆ is a hydroxy group, an acyl group or an epoxy group.

The carbon number of the acyl group is not particularly limited, but it is preferably 1 or more and 18 or less, and more preferably 1 or more and 6 or less. The acyl group includes an acetoacetoxy group.

The divalent organic group is not particularly limited, but an alkylene group having 1 to 10 carbon atoms is preferable. Examples of the alkylene group having 1 to 10 carbon atoms include methylene group, ethylene group, trimethylene group, propylene group, butylene group, hexylene group, cyclohexylene group, heptylene group, octylene group, 2-ethylhexylene group, nonylene. Group, decylene group and the like.

The alkylene group or the acyl group is at least one alkyl group having 1 to 8 carbon atoms, phenoxyalkyl group (carbon number of alkyl group: 1 to 8 carbon atoms), phenyl group, or cyclohexyl group. You may have as a substituent.

Specific examples of the component (a3-1) include, for example, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 2-hydroxymethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1,4-cyclohexanedimethanol (meth)monoacrylate and the like can be mentioned. Among them, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, and acetoacetoxyethyl (meth)acrylate are preferable from the viewpoint of adhesiveness.

The component (a3-1) can be used alone or in combination of two or more. As the component (a3-1), a commercially available product or a synthetic product may be used. Examples of commercially available products include, for example, 2HEA (above, Nippon Shokubai Co., Ltd.), 4HBA (above, Nippon Kasei Co., Ltd.), light ester HOA (N), light ester HOP-A (N), light acrylate HOB. -A, epoxy ester M-600A (above, Kyoeisha Chemical Co., Ltd.), CHDMMA (above, Nippon Kasei Co., Ltd.), GMA (Mitsubishi Gas Chemical Co., Ltd.), AAEM (above, Nippon Synthetic Chemical Industry Co., Ltd.) ) And the like.

<<(a3-2) (meth)acrylamide monomer having hydroxy group, acyl group or epoxy group>>
The (meth)acrylamide monomer having a hydroxy group, an acyl group or an epoxy group (hereinafter, also referred to as component (a3-2)) typically has a structure represented by the following chemical formula 3.

In the above chemical formula 3,
R ₇ is a hydrogen atom or a methyl group, R ₈ is a single bond or a divalent organic group, R ₉ is a hydroxy group, an acyl group or an epoxy group, and R ₁₀ is a hydrogen atom or a carbon group. It is an alkyl group having a number of 1 or more and 10 or less.

As the divalent organic group, an alkylene group having 1 to 10 carbon atoms is preferable. Further, the alkylene group or the acyl group may have at least one alkyl group having 1 to 8 carbon atoms, a phenyl group or a cyclohexyl group as a substituent.

Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, t-butyl group, isobutyl group, n-hexyl group, and 2-hexyl group. Group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, t-heptyl group, n-octyl group, isooctyl group, t-octyl group Group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group and the like.

The carbon number of the acyl group is also not particularly limited, but it is preferably 1 or more and 18 or less, more preferably 1 or more and 6 or less. The acyl group includes an acetoacetoxy group.

Specific examples of the component (a3-2) include, for example, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(2,2-dimethyl-β. -Hydroxyethyl)(meth)acrylamide, diacetone (meth)acrylamide and the like can be mentioned. Among them, N-(2-hydroxyethyl)(meth)acrylamide is preferable from the viewpoint of improving adhesiveness.

The component (a3-2) can be used alone or in combination of two or more. As the component (a3-2), a commercially available product or a synthetic product may be used. Examples of commercially available products include HEAA (registered trademark) (manufactured by KJ Chemicals Co., Ltd.) and DAAM (manufactured by Nippon Kasei Co., Ltd.).

The component (a3-1) and the component (a3-2) may be used alone or in combination. When the component (a3-1) and the component (a3-2) are used in combination, hydrophilicity can be ensured. This makes it possible to keep the glass transition temperature of the copolymer (A) low while maintaining good adhesiveness to the polar base material.

The content of the structural unit derived from the component (a3) in the copolymer (A) is such that the total amount of the structural units derived from the component (a1), the component (a2) and the component (a3) is 100% by mass, It is more than 0 mass% and 20 mass% or less. If the content exceeds 20% by mass, the suppression of edge bubbles, the adhesiveness, the durability, and the suppression of warp and dent are deteriorated due to the effects of the increase in the glass transition temperature and the increase in the degree of crosslinking. The lower limit of the content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. Further, the upper limit of the content is preferably less than 15 parts by mass, more preferably 10% by mass or less.

[(A4): Structural unit derived from monomer other than components (a1) to (a3)]
The copolymer (A) according to the present invention is, as an optional component, a monomer other than the components (a1) to (a3), which is copolymerizable with the components (a1) to (a3) described above (hereinafter, simply referred to as “component ( a4)” also may be included).

As the component (a4), known components can be used unless the effects of the present invention are impaired. Specifically, for example, carboxyl such as (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric acid anhydride, crotonic acid, itaconic acid, itaconic anhydride, myristoleic acid, palmitoleic acid, or oleic acid. Group-containing monomer: benzyl (meth)acrylate, phenyl (meth)acrylate, o-phenylphenol (meth)acrylate phenoxy (meth)acrylate, p-t-butylphenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy Propyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, ethylene oxide modified cresol (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, Monomers having a benzene ring such as methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, cresyl (meth)acrylate, and polystyryl (meth)acrylate; hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2 -Monomers having a naphthalene ring such as naphthoxyethyl acrylate and 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate; monomers having a biphenyl ring such as biphenyl (meth)acrylate; 2-methacryloyloxyethyldiphenylphos Phosphate group-containing (meth)acryl monomers such as phosphate (meth)acrylate, trimethacryloyloxyethyl phosphate (meth)acrylate, and triacryloyloxyethyl phosphate (meth)acrylate; sodium sulfopropyl (meth)acrylate, 2- (Meth)acrylic monomer having a sulfonic acid group such as sodium sulfoethyl (meth)acrylate and sodium 2-acrylamido-2-methylpropanesulfonate; (meth)acrylic monomer having a urethane group such as urethane (meth)acrylate; dimethylamino (Meth)acrylic monomer having an amino group such as ethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, Nt-butylaminoethyl (meth)acrylate, (meth)acryloyloxyethyltrimethylammonium chloride; vinyltrimethoxysilane Vinyl triet Vinyl monomers having silane groups such as xysilane, vinyltris(β-methoxyethyl)silane, vinyltriacetylsilane, methacryloyloxypropyltrimethoxysilane; styrene, chlorostyrene, α-methylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, propion. Examples thereof include vinyl acid salt, acrylonitrile, vinyl pyridine, (meth)acryloylmorpholine, and 2-(meth)acryloyloxyethylphthalic acid.

The above-mentioned component (a4) can be used alone or in combination of two or more kinds. From the viewpoint that the reaction with the cross-linking agent (B) described below can be easily controlled, and that the molecular weight is unlikely to be high when the copolymer (A) according to the present invention is produced, the component (a4) is It is preferable not to contain olefinic monomers such as ethylene and propylene.

The content of the constituent unit derived from the component (a4) in the copolymer (A) is 0. 0 with respect to 100 parts by mass in total of the constituent units derived from the component (a1), the component (a2) and the component (a3). It is preferable that the amount is from 01 part by mass to 10 parts by mass. It is more preferably 0.1 part by mass or more and 5 parts by mass or less.

In the copolymer (A) according to the present invention, among the components (a1) to (a4), a homopolymer has a glass transition temperature of 50° C. or higher (meth)acrylic acid ester monomer (hereinafter, simply referred to as “meth”). It is preferable to (selectively) contain a structural unit derived from “component (a′)”. Such component (a′) can secure the hardness of the pressure-sensitive adhesive layer at room temperature that requires dent resistance, and softens at a heating durability test temperature of 80° C. or higher at which warpage occurs, The pressure-sensitive adhesive layer can have stress relaxation properties. This makes it possible to suppress warpage. Further, it is excellent in polymerizability with the above-mentioned component (a1) and the like, and is excellent in that durability and adhesive strength (particularly reworkability) can be improved and warpage and dents can be suppressed.

<(Meth)acrylic (co)polymer (F)>
In the pressure-sensitive adhesive for an optical film according to the present invention, in addition to the copolymer (A), a homopolymer includes a structural unit derived from a (meth)acrylic monomer having a glass transition temperature of 50° C. or higher, and a copolymer It is preferable to further include a (meth)acrylic (co)polymer (F) having a weight average molecular weight (Mw) smaller than that of the polymer (A) (hereinafter, simply referred to as “(co)polymer (F)”). .. Such a (co)polymer (F) has a constitutional unit which is similar to that of the copolymer (A), but as a high softening point resin (E) described later, as an acrylic resin having a low molecular weight component. It exists separately. Therefore, the (co)polymer (F) can move freely in the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive for an optical film containing the (co)polymer (F). This is excellent in that stress relaxation can be easily imparted to the pressure-sensitive adhesive layer. Further, unlike the high softening point resin (E), the (co)polymer (F) has the same acrylic component as the copolymer (A), and therefore has good compatibility. Therefore, as compared with the case where the pressure-sensitive adhesive layer contains the high softening point resin (E) (there is little clouding, it can occur), it is excellent in that it becomes less cloudy (preferably no clouding). .. Therefore, by adding the (co)polymer (F) and imparting the various properties described above, the hardness of the pressure-sensitive adhesive layer at room temperature, which requires dent resistance, can be secured. In addition, it is excellent in that it can soften at a heating durability test temperature of 80° C. or higher at which a warp occurs, thereby giving the pressure-sensitive adhesive layer a stress relaxation property and suppressing the warp.

[Weight average molecular weight of (co)polymer (F)]
The weight average molecular weight (Mw) of the (co)polymer (F) is not particularly limited as long as the weight average molecular weight (Mw) is smaller than that of the copolymer (A), but is preferably 500 or more and 100,000 or less. .. The weight average molecular weight is more preferably 800 or more and 80,000 or less, and further preferably 1,000 or more and 50,000 or less. The (co)polymer (F) having a molecular weight in the above range has a constitutional unit which is similar to that of the copolymer (A), but exists separately as a low molecular weight acrylic resin. Therefore, in the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive for an optical film containing the (co)polymer (F), the (co)polymer (F) can move freely. This is excellent in that stress relaxation can be easily imparted to the pressure-sensitive adhesive layer. Further, since the (co)polymer (F) is an acrylic component similar to the copolymer (A), the compatibility is good and it becomes difficult for the pressure-sensitive adhesive layer to become cloudy (preferably cloudy). It is preferable).

In the pressure-sensitive adhesive for an optical film according to the present invention, the component (a′) may be contained in the copolymer (A), or the (co)polymer (F) may be included separately from the copolymer (A). May be contained.

In order to efficiently exert the effects of the component (a′) and the (co)polymer (F), the component (a′) may be a constituent component of the copolymer (A), or The (co)polymer (F) may be present separately from the polymer (A). That is, the components (a1) to (a4) contained in the copolymer (A) and the component (a') may be copolymerized. Further, the copolymer (A) and the component (a′) may be polymerized by multistage polymerization, or the (co)polymer (F) may be blended separately from the copolymer (A). Good.

In the present invention, the structure of the (meth)acrylic monomer used as the component (a′) or used in the (co)polymer (F) is not particularly limited.

Specific examples of the (meth)acrylic monomer constituting the (co)polymer (F) include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and acrylonitrile. , (Meth)acrylamide, N-methylol(meth)acrylamide, dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, diethyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, diacetone(meth)acrylamide, acryloyl Moropholin, 2-methacryloyloxyethyl phthalic acid, tetrahydrofurfuryl (meth)acrylate, methyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, Isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n -Pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n- (Meth)acrylic acid (C1-20) alkyl ester such as octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate Further, for example, cycloalkyl (meth)acrylate (for example, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylate (for example, benzyl (meth)acrylate, etc.), polycyclic (meth) ) Acrylate (for example, 2-isobornyl(meth)acrylate, 2-norbornylmethyl(meth)acrylate, 5-norbornen-2-yl-methyl(meth)acrylate, 3-methyl-2-norbornylmethyl(meth) ) Acrylate), hydroxy group-containing (meth)acrylic acid esters (for example, hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)meth). (Tacrylate, etc.), alkoxy group or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl) (Meth)acrylate, ethylcarbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc., epoxy group-containing (meth)acrylic acid esters (eg, glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid Esters (for example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, Octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate and the like, alkylaminoalkyl (meth)acrylate (for example, dimethylaminoethyl (meth)acrylate and the like) and the like can be mentioned. These (meth)acrylic monomers may be used alone or in admixture of two or more.

An acrylic oligomer or acrylic polymer can also be used as the (co)polymer (F). Specific examples of the acrylic oligomer include, for example, "ARUFON (Alfon, registered trademark)" manufactured by Toagosei Co., Ltd., "Actflow (registered trademark)" manufactured by Soken Kagaku Co., Ltd., "JONCRYL (registered trademark)" )” and “Clarity (registered trademark)” manufactured by Kuraray Co., Ltd., and the like.

Specific examples of the (meth)acrylic monomer whose glass transition temperature of the homopolymer used as the above-mentioned component (a') or used in the (co)polymer (F) is 50°C or higher are shown below. However, it is not limited to these. The values in parentheses indicate the glass transition temperature of the homopolymer.

Specific examples include, for example, isobornyl acrylate (94° C.), dicyclopentenyl acrylate (120° C.), dicyclopentanyl acrylate (120° C.), acrylonitrile (97° C.), acrylamide (165° C.), N-methylol acrylamide. (150°C), dimethylacrylamide (119°C), N-isopropylacrylamide (134°C), diethylacrylamide (81°C), dimethylaminopropylacrylamide (134°C), diacetoneacrylamide (77°C), acryloylmorpholine (145). C), 2-methacryloyloxyethyl phthalic acid (55 C), methyl metal acrylate (105 C), ethyl methacrylate (65 C), t-butyl methacrylate (107 C), cyclohexyl methacrylate (66 C), tetrahydrofurfuryl Methacrylate (60° C.), benzyl methacrylate (54° C.), isobornyl methacrylate (180° C.), dicyclopentenyloxyethyl methacrylate (50° C.), dicyclopentanyl methacrylate (175° C.) and the like can be mentioned. These may be used alone or in combination of two or more.

The preferable content of the component (a′) in the copolymer (A) (the blending amount of the (meth)acrylic monomer having a glass transition temperature of a homopolymer as a raw material monomer of 50° C. or higher) is as follows. .. That is, from the viewpoint of more efficiently exhibiting the effect of the present invention, it is preferably more than 0% by mass and 20% by mass or less with respect to 100% by mass of the total amount of the constituent units constituting the copolymer (A). The content is more preferably 0.1% by mass or more and 15% by mass or less, and particularly preferably 0.5% by mass or more and 10% by mass or less. It is preferable that the content of the component (a') is 20% by mass or less, because it becomes easier to achieve both suppression of dents and warpage, and the like.

The content of the (co)polymer (F) according to the present invention is preferably 20% by mass or less based on 100% by mass of the total amount of the pressure-sensitive adhesive for an optical film, from the viewpoint of more efficiently exhibiting the effect of the present invention. is there. The content is more preferably 0.1% by mass or more and 15% by mass or less, and particularly preferably 0.5% by mass or more and 10% by mass or less. When the content of the (co)polymer (F) is 20% by mass or less, advantages such as easy suppression of dents and warpage can be obtained.

The glass transition temperature of the homopolymer may be 50° C. or higher, but the glass transition temperature is preferably 50° C. or higher and 200° C. or lower from the viewpoint of easily balancing the suppression of dents and warpage. C. or higher and 150.degree. C. or lower are more preferable, and 60.degree. C. or higher and 120.degree. C. or lower are still more preferable. The glass transition temperature is a value measured by differential scanning calorimetry of the above homopolymer (homopolymer).

The above-mentioned copolymer (A) and (co)polymer (F) can be used alone or in combination of two or more kinds.

[Method for producing (meth)acrylic acid ester copolymer (A)]
Next, a method for producing the copolymer (A) will be described. In the present invention, the method for producing the copolymer (A) is not particularly limited. Specifically, conventionally known methods such as a solution polymerization method using a polymerization initiator, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, a reverse phase suspension polymerization method, a thin film polymerization method, and a spray polymerization method are used. You can Examples of the polymerization control method include adiabatic polymerization method, temperature control polymerization method and isothermal polymerization method. As the polymerization initiator, either a thermal polymerization initiator or a photopolymerization initiator may be used. In addition to or in addition to the method of initiating the polymerization with a polymerization initiator, a method of irradiating active energy rays such as radiation, electron beams, and ultraviolet rays to initiate the polymerization can also be employed. Among them, the solution polymerization method using a thermal polymerization initiator or the bulk polymerization method using a photopolymerization initiator is more preferable because the molecular weight can be easily adjusted and impurities can be reduced.

In the solution polymerization method using a thermal polymerization initiator, a thermal polymerization initiator is added to a monomer solution as a raw material of the copolymer (A), for example, a raw material monomer solution made of the above-mentioned monomers to carry out a polymerization reaction. More specifically, ethyl acetate, toluene, methyl ethyl ketone, acetone or the like is used as a solvent, and 0.01 part by mass or more and 1 part by mass or less of a thermal polymerization initiator is preferably added to 100 parts by mass of the total amount of raw material monomers. To do. Then, in a nitrogen atmosphere, for example, a reaction temperature is 40° C. or higher and 90° C. or lower, and a reaction time is 3 hours or longer and 10 hours or shorter.

Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis(2-methylbutyronitrile), azobiscyanovaleric acid and 2,2′-azobis( 4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2.4-dimethylvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'- Azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane-1-carbonitrile), 2,2′-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2 '-Azobis(N-butyl-2-methylpropionamide), 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis[2-(2- Imidazolin-2-yl)propane]disulfate dihydrate,2,2'-azobis(2-methylpropionamidine)dihydrochloride,2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hide Rate, 2,2′-azobis[2-(2-imidazolin-2-yl)propane], 2,2′-azobis(1-imino-1-pyrrolidino-2-methylpropane)dihydrochloride, 2,2′ -Azo compounds such as azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; t-butylperoxypivalate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate , Organic peroxides such as di-t-butyl peroxide, cumene hydroperoxide, benzoyl peroxide and t-butyl hydroperoxide; inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate Things can be mentioned. These thermal polymerization initiators can be used alone or in combination of two or more.

As the bulk polymerization method using a photopolymerization initiator, for example, a method of adding a raw material monomer and a photopolymerization initiator and irradiating an active energy ray at a reaction start temperature of 20° C. or higher and 35° C. or lower under a nitrogen atmosphere Is mentioned. When the temperature in the reaction system rises by 5° C. or more and 15° C. or less from the reaction start temperature, the reaction is stopped by introducing air into the reaction system and the copolymer (A) is obtained.

Examples of active energy rays used in the bulk polymerization method include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron rays. Ultraviolet rays are preferably used from the viewpoints of good controllability and handleability, cost and the like. More preferably, ultraviolet light having a wavelength of 200 nm or more and 400 nm or less is used. Ultraviolet rays can be irradiated by using a light source such as a high pressure mercury lamp, a microwave excitation type lamp, a chemical lamp, and a black light. The illuminance is preferably 3.2 mW/cm ² or more and 5.6 mW/cm ² or less.

Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-. 2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. Acetophenones; benzophenones such as benzophenone, 4-chlorobenzophenone and 4,4′-diaminobenzophenone; benzoin ethers such as benzoinpropyl ether and benzoin ethyl ether; thioxanthones such as 4-isopropylthioxanthone; 1-hydroxy Examples thereof include cyclohexyl phenyl ketone, xanthone, fluorenone, camphorquinone, benzaldehyde and anthraquinone. These photopolymerization initiators can be used alone or in admixture of two or more.

A commercially available product may be used as the photopolymerization initiator. Examples of commercially available products include, for example, Irgacure (registered trademark) 184, 819, 907, 651, 1700, 1800, 819, 369, 261, Darocur (registered trademark) TPO, 1173 (above, manufactured by BASF Japan Ltd.), Ezacure. (Registered trademark) KIP150, TZT (above, manufactured by DKSH Japan Co., Ltd.), Kayacure (registered trademark) BMS, DMBI (above, manufactured by Nippon Kayaku Co., Ltd.) and the like.

The amount of the photopolymerization initiator used is preferably 0.0005 parts by mass or more and 1 part by mass or less based on 100 parts by mass of the total amount of the raw material monomers. The amount used is more preferably 0.002 parts by mass or more and 0.5 parts by mass or less.

Further, a chain transfer agent can be used to adjust the molecular weight of the copolymer (A). Examples of chain transfer agents include, for example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its ester, 2-ethylhexyl. Mercaptans such as thioglycol and octyl thioglycolate; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol, allyl alcohol; halogenation of chloroethane, fluoroethane, trichloroethylene, etc. Hydrocarbons; carbonyls such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butyraldehyde, furfural, benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, α-methylstyrene, etc. Is mentioned. These chain transfer agents may be used alone or in combination of two or more.

The production method for synthesizing the (co)polymer (F) is the same as the production method for the copolymer (A) except that the kind and amount of the monomer, the amount of the polymerization initiator used and the like are changed. It is the same.

<Crosslinking agent (B)>
The pressure-sensitive adhesive for optical films of the present invention preferably contains a crosslinking agent (B). The cross-linking agent (B) reacts with the (meth)acrylic acid ester copolymer (A) to form a cross-linked structure. Therefore, in the pressure-sensitive adhesive for optical films, it can mainly contribute to adhesiveness (tackiness) and durability.

In the present invention, the crosslinking agent (B) contains at least one selected from the group consisting of an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound, a polyfunctional (meth)acrylic acid ester monomer, and a peroxide. Is preferred. Below, these various crosslinking agents are demonstrated.

[Isocyanate compound]
In the present invention, specific examples of the isocyanate compound used as the crosslinking agent (B) include dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), and 2,6-tolylene diisocyanate (2 , 6-TDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI). ), tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI) and other aromatic diisocyanates; hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate , Aliphatic diisocyanates such as norbornane diisocyanatomethyl (NBDI); such as transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12-MDI (hydrogenated MDI) Examples thereof include alicyclic diisocyanates; carbodiimide-modified diisocyanates of the above diisocyanates; or these isocyanurate-modified diisocyanates. An adduct of the above-mentioned isocyanate compound and a polyol compound such as trimethylolpropane, polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), a biuret body or an isocyanurate body of these isocyanate compounds can also be preferably used.

As these isocyanate compounds, commercially available products or synthetic products may be used.

Examples of commercially available products include Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, Coronate (registered trademark) 2031 (all manufactured by Tosoh Corporation), Takenate (registered trademark) D-102, Takenate (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (all manufactured by Mitsui Chemicals, Inc.), Duranate (registered trademark) 24A-100, Duranate (registered trademark) TPA-100, Duranate (registered trademark) TKA-100, Duranate (registered trademark) P301-75E, Duranate (registered trademark) E402-90T, Duranate (registered trademark) E405-80T, Duranate (Registered trademark) TSE-100, Duranate (registered trademark) D-101, Duranate (registered trademark) D-201 (above, manufactured by Asahi Kasei Corporation), Sumijour (registered trademark) N-75, N-3200, N- 3300 (above, manufactured by Sumika Covestro Urethane Co., Ltd.), Samprene (registered trademark) P-6090 (PTMG/MDI system), Samprene (registered trademark) P-663L (PTMG/TDI system), Samprene (registered trademark) P -664 (PTMG/TDI system), Samprene (registered trademark) P-665 (PTMG/TDI system), Samprene (registered trademark) P-667 (PTMG/TDI system), Samprene (registered trademark) P-868 (PTMG/ HMDI-based), Samprene (registered trademark) P-870 (PTMG/HMDI-based), Sampren (registered trademark) C-810" (PPG/TDI-based) (above, Sanyo Kasei Co., Ltd.), and the like. It is not limited to these.

The isocyanate compound may be used in the form of an unblocked isocyanate compound. It may also be used in the form of a blocked isocyanate compound obtained by reacting with a blocking agent that protects an isocyanate group. The blocked isocyanate compound may be a commercially available product or a synthetic product. Examples of commercially available blocked isocyanate compounds include Duranate (registered trademark) MF-B60X (block 1,6-hexamethylene diisocyanate) and Duranate (registered trademark) MF-K60X (block 1,6-hexa) manufactured by Asahi Kasei Corporation. Methylene diisocyanate), Tosoh Corporation Coronate (registered trademark) AP-M, 2503, 2507, 2513, 2515, Millionate (registered trademark) MS-50, Mitsui Chemicals, Inc. Takenate (registered trademark) B-830 ( Block tolylene diisocyanate), B-815N (block 4,4′-methylenebis(cyclohexyl isocyanate)), B-842N (block 1,3-bis(isocyanatomethyl)cyclohexane), B-846N (block 1, 3-bis(isocyanatomethyl)cyclohexane), B-874N (block isophorone diisocyanate), B-882N (block 1,6-hexamethylene diisocyanate), DIC Corporation Vernock (registered trademark) ) D-500 (block tolylene diisocyanate), D-550 (block 1,6-hexamethylene diisocyanate), Elastron (registered trademark) BN-P17 (block) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. 4,4′-diphenylmethane diisocyanate), BN-04, BN-08, BN-44, BN-45 (above, block urethane-modified polyvalent isocyanate) and the like. Of these, Duranate (registered trademark) MF-K60X is preferable.

From the viewpoint of further improving the durability of the pressure-sensitive adhesive, the isocyanate compound is preferably used in the form of an unblocked isocyanate compound.

Further, the isocyanate compound according to the present invention preferably has a number average molecular weight (Mn) of 900 or more and 10,000 or less. By including an isocyanate compound having such a number average molecular weight as the cross-linking agent (B), a gradual cross-linking effect due to the long distance between cross-linking points is suppressed while suppressing the clustering of the cross-linking structure of the copolymer (A). Can be expressed. As a result, it is possible to more efficiently achieve both suppression of air bubbles at the ends and suppression of peeling.

That is, according to a more preferred embodiment of the present invention, the crosslinking agent (B) contains an isocyanate compound having a number average molecular weight (Mn) of 900 or more and 10,000 or less (excluding the blocked isocyanate compound).

From the viewpoint of further exerting the effect of the present invention, the number average molecular weight (Mn) of the isocyanate compound is more preferably 900 or more and 7,000 or less. The number average molecular weight (Mn) is more preferably 1,000 or more and 5,000 or less. The number average molecular weight (Mn) of the isocyanate compound can be determined by the same method as the method for measuring the weight average molecular weight of the copolymer (A) shown in the examples.

[Carbodiimide compound]
In the present invention, the carbodiimide compound used as the crosslinking agent (B) is not particularly limited. As an example, a high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst is used.

Examples of the diisocyanate used in the decarboxylation condensation reaction include, for example, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′- Diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4 -Diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and the like.

Examples of the carbodiimidization catalyst used in the decarboxylation condensation reaction include, for example, 1-phenyl-2-phospholen-1-oxide, 3-methyl-2-phospholen-1-oxide, 1-ethyl-3-methyl- Examples thereof include 2-phospholen-1-oxide, 1-ethyl-2-phospholen-1-oxide, and phospholene oxides such as their 3-phosphorene isomers.

The high molecular weight polycarbodiimide may be a commercially available product or a synthetic product. Examples of commercially available products include Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd. Among them, Carbodilite (registered trademark) V-01, V-03, V-05, V-07 and V-09 are preferable because they have excellent compatibility with an organic solvent.

[Oxazoline compound]
In the present invention, the oxazoline compound used as the crosslinking agent (B) is not particularly limited. However, an oxazoline group-containing acrylic/styrene polymer having a main chain composed of an acrylic skeleton or a styrene skeleton and having an oxazoline group on the side chain of the main chain is preferable. Further, an oxazoline group-containing polymer such as an oxazoline group-containing acrylic polymer having a main chain composed of an acrylic skeleton and having an oxazoline group on the side chain of the main chain is also preferable.

Examples of the oxazoline group include a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. Among them, the 2-oxazoline group is preferable.

Further, the oxazoline group-containing polymer may have a polyoxyalkylene group in addition to the oxazoline group.

Specific examples of the oxazoline group-containing polymer include oxazoline group-containing acryl such as Epocros (registered trademark) WS-300, Epocros (registered trademark) WS-500, and Epocros (registered trademark) WS-700 manufactured by Nippon Shokubai Co., Ltd. Examples of the polymer include oxazoline group-containing acrylic/styrene polymers such as Epocros (registered trademark) K-1000 series and Epocros (registered trademark) K-2000 series manufactured by Nippon Shokubai Co., Ltd.

[Epoxy compound]
In the present invention, the epoxy compound used as the cross-linking agent (B) is not particularly limited, and a known epoxy-based cross-linking agent can be appropriately used. Examples of commercially available epoxy compounds include "TETRAD (registered trademark)-C" and "TETRAD (registered trademark) -X" manufactured by Mitsubishi Gas Chemical Co., Inc. and "ADEKA Resin (registered trademark) EPU series manufactured by ADEKA CORPORATION. Liquid epoxy resins such as “Adeka Resin (registered trademark) EPR series” and “Celoxide (registered trademark)” manufactured by Daicel Corporation. These liquid epoxy resins are preferable because they facilitate the mixing operation when producing the pressure-sensitive adhesive for optical films.

[Polyfunctional (meth)acrylic acid ester monomer]
The polyfunctional (meth)acrylic acid ester monomer is a (meth)acrylic acid ester monomer having a plurality of radically polymerizable functional groups. Such compounds can also be used as the crosslinking agent (B).

Examples of polyfunctional (meth)acrylic acid ester monomers include hydrocarbon-based or hydrocarbon ether-based polyfunctional monomers. The hydrocarbon-based or hydrocarbon ether-based polyfunctional monomer is a compound in which a hydroxy group of a polyhydric alcohol having a hydrocarbon group or a hydrocarbon ether group having 10 to 100 carbon atoms as a main skeleton is (meth)acrylated. is there. The compound is preferable from the viewpoint of improving adhesiveness by crosslinking. Examples of the hydrocarbon group of the polyhydric alcohol include a linear or branched aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and a hydrocarbon group obtained by combining these hydrocarbon groups. .. Examples of the hydrocarbon ether group include those obtained by etherifying the hydrocarbon group. Examples of the polyhydric alcohol having a hydrocarbon ether group as a main skeleton include compounds (addition number of 1 or more and 30 or less) in which an alkylene oxide having 2 or more and 4 or less carbon atoms is added to the polyhydric alcohol. Further, a polyalkylene glycol obtained from an alkylene oxide having 2 to 4 carbon atoms (addition number: 1 to 30) can be used.

Specific examples of the hydrocarbon-based bifunctional monomer include, for example, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth). ) Acrylate, di(meth)acrylate of alkylene glycol such as neopentyl glycol di(meth)acrylate; alicyclic carbonization such as cyclohexanedimethanol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate Di(meth)acrylate of a diol compound having a hydrogen group; di(meth)acrylate of a diol compound having an aromatic hydrocarbon group such as bisphenol A di(meth)acrylate and the like.

Specific examples of the hydrocarbon ether-based bifunctional monomer include, for example, alkoxylated hexanediol di(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate, and alkoxylated di(meth)acrylate. , An alkoxylated neopentyl glycol di(meth)acrylate, an alkoxylated bisphenol A di(meth)acrylate, or the like, which is a compound obtained by adding an alkylene oxide to an alkylene glycol or diol compound described in the above hydrocarbon-based bifunctional monomer. Examples thereof include (meth)acrylate. Specific examples of the hydrocarbon ether-based bifunctional monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, Examples include polyalkylene glycol di(meth)acrylates such as tripropylene glycol di(meth)acrylate and dipropylene glycol di(meth)acrylate, and dioxane glycol di(meth)acrylate.

Examples of hydrocarbon-based or hydrocarbon ether-based trifunctional monomers and tetrafunctional monomers include, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glyceryl tri(meth)acrylate, Tri(meth)acrylate or tetra(meth)acrylate of a tri- or tetraol compound such as pentaerythritol tetra(meth)acrylate or trimethylolpropane tetra(meth)acrylate, or a compound obtained by adding an alkylene oxide to the above-mentioned tri- or tetraol compound. And tri(meth)acrylate or tetra(meth)acrylate of

Examples of the above-mentioned hydrocarbon-based or hydrocarbon ether-based monomers include polyester poly(meth)acrylates having at least two (meth)acryloyl groups at their terminals, epoxy (meth)acrylates, and the like.

(Peroxide)
In the present invention, the peroxide used as the crosslinking agent (B) is not particularly limited, and known ones can be used. Further, as the peroxide, one having a one-minute half-life temperature of 80° C. or higher and 160° C. or lower is preferable in consideration of productivity and stability. It is more preferable that the one-minute half-life temperature is 80° C. or higher and 140° C. or lower. The temperature is more preferably 80°C or higher and 125°C or lower, and particularly preferably 90°C or higher and 125°C or lower. The "half-life of peroxide" is an index showing the decomposition rate of peroxide, and means the time until the residual amount of peroxide is halved. The decomposition temperature for obtaining a half-life at a certain time and the half-life time at a certain temperature are described in manufacturer catalogs and the like. For example, it is described in Organic Peroxide Catalog 9th Edition (May 2003) issued by NOF CORPORATION.

Examples of such peroxides include, for example, diisopropyl peroxydicarbonate (1 minute half-life temperature 88.3° C., temperature in parentheses indicates 1 minute half-life temperature), di(2-ethylhexyl). ) Peroxydicarbonate (90.6°C), bis(4-t-butylcyclohexyl)peroxydicarbonate (92.1°C), di-sec-butylperoxydicarbonate (92.4°C), t- Butyl peroxy neodecanoate (103.5°C), t-hexyl peroxypivalate (109.1°C), t-butyl peroxypivalate (110.3°C), dilauroyl peroxide (116. 4° C.), bis-n-octanoyl peroxide (117.4° C.), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (124.3° C.), di(4- Methylbenzoyl) peroxide (128.2° C.), dibenzoyl peroxide (benzoyl peroxide) (130.0° C.), a mixture of dibenzoyl peroxide and benzoyl m-methylbenzoyl peroxide and m-toluoyl peroxide ( 131.1° C.), t-butyl peroxybutyrate (136.1° C.) and the like. Of these, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, and t-butyl peroxy neodecanoate are preferably used. These may be used alone, but it is also preferable to use two or more in combination from the viewpoint of controlling the reactivity. As an example of using two or more kinds in combination, a combination of di(4-t-butylcyclohexyl)peroxydicarbonate and dilauroyl peroxide is preferable.

The peroxide may be a commercially available product or a synthetic product. Examples of commercially available products include, for example, NOF CORPORATION's trade name: “Perloyl (registered trademark, the same applies hereinafter) IB” (85.1° C.), “Park Mill (registered trademark, the same applies below)” (94.0° C.) ), “Perloyl NPP” (94.0° C.), “Perloyl IPP” (88.3° C.), “Perloyl SBP” (92.4° C.), “Peroctyl (registered trademark, the same applies hereinafter) ND” (92.4). °C), "Perloyl TCP" (92.1 °C), "Perloyl OPP" (90.6 °C), "Perhexyl (registered trademark, the same applies hereinafter) ND" (100.9 °C), "Perbutyl (registered trademark, hereinafter)" Same) ND" (103.5°C), "Perbutyl NHP" (104.6°C), "Perhexyl PV" (109.1°C), "Perbutyl PV" (110.3°C), "Perloyl 355" (112). .6° C.), “Perloyl L” (116.4° C.), “Perocta O” (124.3° C.), “Perloyl SA” (131.8° C.), “Perhexa (registered trademark, the same applies hereinafter) 25O” ( 118.8° C.), “Perhexyl O” (132.6° C.), “Nyper (registered trademark, the same applies hereinafter) PMB” (128.2° C.), “Perbutyl O” (134.0° C.), “Kniper BMT” (131.1°C), "Nyper BW" (130.0°C), "Nyper BMT-K40" (131.1°C), "Nyper BMT-M" (131.1°C), "Perhexa MC" (142 .1° C.), “Perhexa TMH” (147.1° C.), “Perhexa HC” (149.2° C.), “Perhexa C” (153.8° C.), “Pertetra (registered trademark, the same applies hereinafter) A” ( 153.8°C), "Perhexyl I" (155.0°C), "Perbutyl L" (159.4°C), "Perbutyl I" (158.8°C), "Perhexa 25Z" (158.2°C), Examples thereof include "Perbutyl A" (159.9°C) and "Perhexa 22" (159.9°C).

In the present invention, the crosslinking agent (B) may be used alone or in combination of two or more kinds. When 2 or more types are combined, 2 or more types (for example, 2 types of isocyanate compounds) of crosslinking agents of the same system may be combined. You may combine 1 or more types of crosslinking agents of a different type|system|group (for example, 1 type of isocyanate compounds and 1 type of peroxides), respectively.

The content of the crosslinking agent (B) in the pressure-sensitive adhesive for an optical film of the present invention is not particularly limited, but is 0.001 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the copolymer (A). Preferably. The content is more preferably 0.01 part by mass or more and 10 parts by mass or less, further preferably 0.03 parts by mass or more and 5 parts by mass or less. Particularly preferably, the amount is 0.05 parts by mass or more and 3 parts by mass or less. It is preferable that the content of the crosslinking agent (B) is 0.001 part by mass or more from the viewpoint that foaming can be suppressed during heating durability. Further, it is preferable from the viewpoint that the generation of dents can be suppressed. On the other hand, when the content is 20 parts by mass or less, the crosslinked structure does not become too dense, and durability is ensured even in a harsh environment, which is preferable.

<Silane coupling agent (C)>
The pressure-sensitive adhesive for optical films of the present invention preferably further contains a silane coupling agent (C). The silane coupling agent (C) can contribute mainly to improvement of durability and adhesion to glass when the adherend is glass in the pressure-sensitive adhesive for optical film. In the present specification, the “silane coupling agent” means a silane compound having no siloxane bond (Si—O—Si bond) and having two or more reactive groups in the molecule.

In the present invention, the silane coupling agent (C) is not particularly limited, but specifically, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxy. Silane, trimethylmethoxysilane, n-propyltrimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltrimethoxysilane, diphenyl Dimethoxysilane, cyclohexylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycid Xypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl Methyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ -Aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane Silane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis-(3-[triethoxysilyl]propyl)tetrasulfide, γ-isocyanatopropyltriethoxysilane, etc. Can be mentioned. Furthermore, a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), an amino group, a mercapto group and a (meth)acryloyl group, and a functional group capable of reacting with these functional groups. Agents. Further, a compound having a hydrolyzable silyl group obtained by reacting each functional group with other coupling agent, polyisocyanate or the like at an arbitrary ratio can also be used.

The silane coupling agent (E) may be a commercially available product or a synthetic product. Examples of commercially available silane coupling agents (E) include KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, and KBM-802. , KBM-803, KBE-846, KBE-9007 (above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The silane coupling agent (C) may be used alone or in combination of two or more.

When the pressure-sensitive adhesive for an optical film of the present invention contains a silane coupling agent (C), the content of the silane coupling agent (C) is not particularly limited. However, it is preferably 0.001 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the copolymer (A). The content is more preferably 0.001 parts by mass or more and 5 parts by mass or less, and further preferably 0.01 parts by mass or more and 3 parts by mass or less. A content of 0.001 parts by mass or more is preferable from the viewpoint that the effect on durability can be exhibited even in a harsh environment. On the other hand, when the content is 10 parts by mass or less, it is preferable from the viewpoint that the deterioration of the heat foaming due to the low molecular weight compound does not occur.

<Silicate oligomer (D)>
The pressure-sensitive adhesive for optical films of the present invention preferably further contains a silicate oligomer (D). The silicate oligomer (D) can mainly contribute to improvement of reworkability in the pressure-sensitive adhesive for optical films.

The silicate oligomer (D) according to the present invention has a structure represented by the following chemical formula 4.

In Chemical Formula 4, R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group. X ¹ and X ² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group. n is an integer of 1 or more and 100 or less, and preferably an integer of 2 or more and 100 or less. The alkyl group and the phenyl group may or may not be substituted. The alkyl group may have a straight chain structure or a branched chain structure.

In the present invention, a methyl silicate oligomer in which all of R ¹ , R ² , X ¹ and X ^{2 in} the above chemical formula 4 are methyl groups is preferable from the viewpoint of easily achieving both durability and reworkability. The silicate oligomer (D) can be used either alone or as a mixture of two or more kinds.

In the present invention, the weight average molecular weight of the silicate oligomer (D) is not particularly limited. However, it is preferably 300 or more and 30000 or less, more preferably 500 or more and 25000 or less, still more preferably 600 or more and 5000 or less, and particularly preferably 600 or more and 5000 or less. A weight average molecular weight of 300 or more is preferable from the viewpoint of easily ensuring reworkability. On the other hand, it is preferably 30,000 or less from the viewpoint of easily ensuring durability. The weight average molecular weight of the silicate oligomer (D) can be measured by the same method as the method of measuring the weight average molecular weight of the copolymer (A) shown in the examples.

When the pressure-sensitive adhesive for an optical film of the present invention contains the silicate oligomer (D), the content of the silicate oligomer (D) is not particularly limited. However, it is preferably 0.01 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the copolymer (A). The content is more preferably 0.3 parts by mass or more and 10 parts by mass or less, further preferably 0.5 parts by mass or more and 5 parts by mass or less. When the content is 0.01 parts by mass or more, the effect on durability is exhibited even in a harsh environment, which is preferable. On the other hand, when the content is 50 parts by mass or less, it is easy to achieve both reworkability and durability, which is preferable.

<High softening point resin (E)>
The pressure-sensitive adhesive for optical films of the present invention preferably further contains a high softening point resin (E) having a softening point of 60° C. or higher and 200° C. or lower (hereinafter, simply referred to as “high softening point resin (E)”). .. This is because the addition of the high softening point resin (E) makes it possible to provide a pressure-sensitive adhesive that is hard to some extent at room temperature and softens (softens) at high temperatures. By adding the above-mentioned high softening point resin (E) and imparting such characteristics, it becomes hard at room temperature and the occurrence of dents can be effectively suppressed. Further, by softening at a high temperature, stress relaxation can be given in a high temperature (for example, 85° C.) environment, which is preferable in that the occurrence of warpage can be effectively suppressed.

The high softening point resin (E) used in the present invention is preferably a resin having a softening point of 60° C. or higher and 200° C. or lower from the viewpoint that the above-described effects can be effectively exhibited. Therefore, a conventionally known one can be used. Specific examples thereof include, for example, aliphatic petroleum resins, alicyclic hydrocarbon resins, aromatic petroleum resins, fully hydrogenated aliphatic petroleum resins, and fully hydrogenated alicyclic hydrocarbon resins, Petroleum resin such as fully hydrogenated aromatic petroleum resin, partially hydrogenated aliphatic petroleum resin, partially hydrogenated alicyclic hydrocarbon resin, partially hydrogenated aromatic petroleum resin, aromatic hydrocarbon resin, aliphatic Saturated hydrocarbon resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, coumarone-indene resin, rosin acid, polymerized rosin acid and rosin ester resin (rosin acid ester) and other rosin resins (including rosins and rosin derivatives) Preferred), epoxy resin, phenol resin, oil-soluble phenol (resin), or modified resins thereof. These high softening point resins (E) may be used alone or in combination of two or more. Among these, an alicyclic hydrocarbon resin, a terpene phenol resin, and a terpene resin are more preferable from the viewpoint of good compatibility with the copolymer (A). In addition, the resin having a high softening point (E) is a rosin ester resin from the viewpoint that the compatibility with other components of the pressure-sensitive adhesive is very good and transparency is easily obtained when applied to an optical film. Is more preferable.

The high softening point resin (E) may be a synthetic product or a commercially available product.

Examples of commercially available rosin ester-based resins include, for example, Pine Crystal (registered trademark, the same applies hereinafter) KR-85 (softening point 80-87° C., temperature in parentheses indicates softening point), Pine Crystal KR-. 612 (80-90°C), Pine Crystal KR-614 (84-94°C), Pine Crystal KE-100 (95-105°C), Pine Crystal KE-311 (90-100°C), Pine Crystal PE-590 ( 90-100°C), pine crystal KE-359 (94-104°C), pine crystal KE-604 (124-134°C), pine crystal KR-120 (110-130°C), pine crystal KR-140 (130-). 150° C.), Pine Crystal KR-614 (84-94° C.), Pine Crystal D-6011 (84-99° C.), Pine Crystal KR-50M (145-160° C.) (above, manufactured by Arakawa Chemical Industry Co., Ltd.), etc. Is mentioned. These are ultra-light color rosins and are suitably used for optical applications requiring transparency.

Other examples of commercially available rosin ester-based resins include superester A-75 (70-80°C), superester A-100 (95-105°C), superester A-115 (108-120°C). ), super ester A-125 (120-130° C.), Tamanoru (registered trademark, the same applies hereinafter) 460 (182-192° C.) (above, manufactured by Arakawa Chemical Industry Co., Ltd.) and the like.

Examples of commercially available alicyclic hydrocarbon resins include, for example, Alcon (registered trademark, the same applies hereinafter) P-90 (85-95°C), Alcon P-100 (95-105°C), Alcon (registered trademark). ) P-115 (110-120°C), Alcon P-125 (120-130°C), Alcon P-140 (135-145°C), Alcon M-90 (85-95°C), Alcon M-100 (95). -105°C), Alcon M-115 (110-120°C), Alcon M-135 (130-140°C) (all manufactured by Arakawa Chemical Industry Co., Ltd.) and the like.

Examples of commercially available terpene phenolic resins include, for example, Tamanol 803L (145-160°C), Tamanol 901 (125-135°C) (above, manufactured by Arakawa Chemical Industry Co., Ltd.), YS Polystar (registered trademark, the same below). U130 (125-135°C), YS Polystar U115 (110-120°C), YS Polystar T160 (155-165°C), YS Polystar T145 (140-150°C), YS Polystar T130 (125-135°C), YS Polystar T115 (110-120°C), YS Polystar T100 (95-105°C), YS Polystar T80 (75-85°C), YS Polystar S145 (140-150°C), YS Polystar G150 (145-155°C), YS Polystar G125 (120-130 degreeC), YS polystar N125 (120-130 degreeC), YS polystar K125 (120-130 degreeC), YS polystar TH130 (125-135 degreeC) (above, Yasuhara Chemical Co., Ltd. make) etc. are mentioned.

Examples of commercially available terpene resins include, for example, YS resin (registered trademark, the same applies hereinafter) PX1250 (120-130°C), YS resin PX1150 (110-120°C), YS resin PX1000 (95-105°C), YS resin. Resin PX800 (75-85°C), YS resin PX1150N (110-120°C), YS resin TO125 (120-130°C), YS resin TO115 (110-120°C), YS resin TO105 (100-110°C), YS Resin TO85 (80 to 90° C.) (above, Yasuhara Chemical Co., Ltd.) and the like can be mentioned.

When the high softening point resin (E) is added to the pressure-sensitive adhesive for an optical film of the present invention, the addition amount of the high softening point resin (E) is not particularly limited. However, it is preferably 0.1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the copolymer (A). The addition amount is more preferably 0.5 part by mass or more and 25 parts by mass or less, further preferably 1 part by mass or more and 20 parts by mass or less. When the content is 0.1 part by mass or more, it is preferable from the viewpoint that the softening effect is obtained during the durability test. Further, it is preferable from the viewpoint that the occurrence of warpage can be suppressed. On the other hand, the content of 30 parts by mass or less is preferable from the viewpoint that deterioration of durability due to a low molecular weight substance can be suppressed. Further, it is preferable from the viewpoint that durability can be secured even in a harsh environment such that the flexibility of the pressure-sensitive adhesive can be effectively suppressed even in a low temperature region such as -25°C or lower.

The softening point of the high softening point resin (E) is preferably 60° C. or higher and 200° C. or lower. From the viewpoint of improving the tackiness, durability and reworkability, and suppressing the occurrence of warpage and dents, 70°C or higher and 150°C or lower is more preferable. The softening point is more preferably 80°C or higher and 140°C or lower, and particularly preferably 85°C or higher and 130°C or lower. In the present invention, as the softening point, a value measured by the method described in JIS K6863 (1994) is adopted.

<Other additives>
The pressure-sensitive adhesive for optical films of the present invention contains, if necessary, a solvent, a crosslinking accelerator, an antioxidant, a filler, a colorant (such as a pigment or a dye), an ultraviolet absorber, an antioxidant, a chain transfer agent, and a plasticizer. Known additives (other additives) such as agents, softeners, surfactants, antistatic agents, etc. may be contained within a range that does not impair the effects of the present invention.

<Solvent>
The pressure-sensitive adhesive for optical films of the present invention may contain a solvent. By including the solvent, the effect of greatly improving the productivity during coating can be obtained. The solvent is not particularly limited, but esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methyl Alicyclic hydrocarbons such as cyclohexane; organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, and ketones such as acetone. These solvents may be used alone or in combination of two or more.

<Method for producing (preparing) adhesive for optical film>
When the pressure-sensitive adhesive for an optical film according to the present invention contains the copolymer (A) and a component other than the copolymer (A), it can be prepared by mixing the respective components. The order of mixing the components and the mixing temperature are not particularly limited and may be appropriately adjusted by those skilled in the art.

[Use]
The pressure-sensitive adhesive for optical films of the present invention described above is suitable for various uses. For example, it is preferably used for an optical member such as an optical film, and particularly preferably for a thin adhesive optical film used for a large liquid crystal panel in recent years. Examples of such an optical film include a polarizing plate, a retardation plate for preventing coloration, an optical compensation film such as a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for increasing the contrast of the display. Furthermore, the thing in which these are laminated is mentioned.

In the present invention, the form of the pressure-sensitive adhesive layer formed of the above-mentioned pressure-sensitive adhesive for an optical film, the form of an optical member having the pressure-sensitive adhesive layer formed on an optical film or the like, and the form in which the optical film is a polarizing plate. Alternatively, a form in which the optical member is applied to an image display device such as a liquid crystal display device, an organic EL display device, a plasma display (PDP), a micro LED display, a curved display or a flexible display is also provided. Each will be described below.

<Adhesive layer>
According to one aspect of the present invention, there is provided a pressure-sensitive adhesive layer for an optical film, which is formed from the above-mentioned pressure-sensitive adhesive for an optical film of the present invention.

The thickness (film thickness after drying) of the pressure-sensitive adhesive layer of the present invention can be appropriately set by those skilled in the art depending on its application. The thickness is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 75 μm or less. It is more preferably 5 μm or more and 40 μm or less, particularly preferably 7 μm or more and 35 μm or less, and most preferably 10 μm or more and 30 μm or less. The thickness within the above range is preferable from the viewpoint of achieving a good balance between durability and adhesive properties.

The gel fraction of the pressure-sensitive adhesive layer of the present invention immediately after drying is not particularly limited, but is preferably 95% or less from the viewpoint of punching or slitting. Further, it is preferably 40% or more from the viewpoint that there is no concern about dents, warpage or durability on the pressure-sensitive adhesive layer immediately after drying and no aging treatment is required. The gel fraction is more preferably 65% or more. The gel fraction can be adjusted by controlling the amount of crosslinking agent and the amount of peroxide.

[Production method of adhesive layer]
According to another embodiment of the present invention, the pressure-sensitive adhesive layer for an optical film, which comprises applying the above-mentioned pressure-sensitive adhesive for an optical film of the present invention onto a release-treated release sheet, and then subjecting it to a heat treatment to cause a crosslinking reaction. A method of manufacturing the same is also provided.

When the pressure-sensitive adhesive is used in the optical film, the pressure-sensitive adhesive may be applied directly on the optical film to form the pressure-sensitive adhesive layer. However, it is desirable to apply the pressure-sensitive adhesive to a film having releasability to form a pressure-sensitive adhesive layer, and then transfer the film to various optical films for use. Further, the release film having the pressure-sensitive adhesive layer produced in this manner can also be wound into a roll in the production process. The film having releasability can be removed and used when it is cut or processed as needed and attached to various optical films or liquid crystal panels. Furthermore, the film having releasability can also play a role of protecting the pressure-sensitive adhesive layer until the pressure-sensitive adhesive layer is put into practical use. In the present specification, such a film having releasability is also referred to as a release sheet (separator).

Examples of the constituent material of the release sheet include polyethylene, polypropylene, polyethylene terephthalate, plastic films such as polyester film, porous materials such as paper, cloth, non-woven fabric, net, foamed sheet, metal foil, and laminates thereof. The appropriate thin leaf body of the above can be mentioned. A plastic film is preferably used because it has excellent surface smoothness.

The thickness of the release sheet is usually 5 μm or more and 200 μm or less, preferably about 5 μm or more and 100 μm or less.

If necessary, the release sheet may include a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release treatment and antifouling treatment with silica powder, coating type, kneading type, vapor deposition. An antistatic treatment such as a mold can be further performed. In particular, from the viewpoint that the releasability from the pressure-sensitive adhesive layer can be further enhanced, it is preferable to perform a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the release sheet.

In the present invention, the coating method when the pressure-sensitive adhesive for an optical film of the present invention is coated on a release-treated release sheet is not particularly limited, and various known methods can be used. For example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, extrusion coat method by die coater, etc. There is a method.

In the method for producing a pressure-sensitive adhesive layer of the present invention, a step of applying heat treatment after applying the pressure-sensitive adhesive for an optical film described above on a release sheet is performed. The heat treatment step not only serves to dry and remove the solvent in the coating film obtained by coating, but also serves to crosslink the above-mentioned pressure-sensitive adhesive for optical film. The temperature of the heat treatment is preferably 40°C or higher and 150°C or lower, more preferably 50°C or higher and 130°C or lower, and further preferably 80°C or higher and 120°C or lower. By setting the temperature of the heat treatment within the above range, an adhesive layer having excellent adhesive properties can be obtained.

The heat treatment time may be appropriately set, but is preferably 5 seconds or more and 20 minutes or less, more preferably 5 seconds or more and 10 minutes or less, and further preferably 10 seconds or more and 5 minutes or less.

The heat treatment means is not particularly limited, and various known methods can be used. For example, a parallel drying method in which hot air is blown in the same direction as the upper and lower sides of the film, a counter drying method in which hot air is blown in the different direction of the film in the conveying direction of the film, and a float drying method in which hot air is blown directly from above and below the film There is a method.

[Optical member]
According to an aspect of the present invention, there is provided an optical member including the above-mentioned pressure-sensitive adhesive layer for an optical film and the first optical film provided on one surface of the pressure-sensitive adhesive layer.

Further, the optical member of the present invention may further have glass or a second optical film on the surface of the pressure-sensitive adhesive layer of the present invention opposite to the surface on which the first optical film is provided. Here, the “first optical film” and the “second optical film” may be films having the same configuration (material, function, etc.), and different configurations (material, function, etc.) may be used. It may be a film having. Further, in the present invention, a form in which the first optical film (or the second optical film) is a polarizing plate is also provided.

In the present invention, the above-mentioned pressure-sensitive adhesive may be used by directly coating on one side or both sides of the optical film to form a pressure-sensitive adhesive layer. However, for the reasons described above, it is desirable to form the pressure-sensitive adhesive layer on the separator or the like in advance and transfer it to one side or both sides of the optical film before use. In addition, before the transfer, the surface of the optical film may be subjected to a base treatment such as formation of an easily-adhesion treated layer or an antistatic layer depending on the material. Also, the surface of the pressure-sensitive adhesive layer may be subjected to easy adhesion treatment. From the viewpoint of firmly adhering the optical film and the pressure-sensitive adhesive layer, it is preferable to have an easy adhesion treatment layer between the optical film and the pressure-sensitive adhesive layer for an optical film of the present invention.

<Easy adhesion treatment layer (easy adhesion layer)>
The optical member of the present invention preferably further has at least one easy-adhesion treatment layer between the first optical film and the pressure-sensitive adhesive layer for an optical film.

In a more preferred form, the easy adhesion treatment layer has a first easy adhesion treatment layer and a second easy adhesion treatment layer. And the said optical member has the 1st optical film, the 1st easy adhesion treatment layer, the 2nd easy adhesion treatment layer, and the adhesive layer for optical films laminated|stacked in this order. As described above, in the optical member, the configuration having both the first and second easily adhesive treatment layers is preferable from the viewpoint that the optical film and the pressure-sensitive adhesive layer can be more firmly adhered to each other.

The easy-adhesion treatment layer may be one that treats the surface of the member that comes into contact with the pressure-sensitive adhesive layer, such as corona treatment or plasma treatment. Alternatively, a separate member such as a primer layer may be provided on the surface of the member that comes into contact with the pressure-sensitive adhesive layer.

It is preferable that the material forming the primer layer has good adhesion to a member that comes into contact with the primer layer and forms a film having excellent cohesive force. For example, various polymers, metal oxide sols, silica sols and the like are used, and among them, polymers are preferably used. The primer layer may have an antistatic function.

Examples of polymers constituting the primer layer include oxazoline group-containing polymers, polyurethane resins, polyester resins, and polymers having an amino group in the molecule. Among them, polyurethane resin and oxazoline group-containing polymer are more preferably used.

A commercially available product can be used as the oxazoline group-containing polymer. Examples include, but are not limited to, Epocros (registered trademark) series manufactured by Nippon Shokubai Co., Ltd. (for example, Epocros (registered trademark) WS700). Further, as the polyurethane resin, polyester resin, polymers containing an amino group in the molecule, those disclosed in paragraphs “0107” to “0113” of JP2011-105918A can be appropriately adopted.

The thickness of the primer layer is preferably 10 nm or more and 5000 nm or less, and more preferably 50 nm or more and 500 nm or less. Within the above range, optical properties can be maintained while exhibiting sufficient strength and adhesion.

The method for forming the primer layer is not particularly limited, and examples thereof include a method in which the raw material (undercoating agent) for the primer layer is applied using a coating method such as a coating method, a dipping method, or a spray method, and then dried.

<Optical film>
In the present invention, as the optical film (first optical film or second optical film), an optical film such as a polarizing plate, a retardation plate for preventing coloration, and a viewing angle widening film for improving the viewing angle of a liquid crystal display. Examples of the film include a compensation film, a brightness enhancement film for increasing the contrast of a display, and a film in which these are laminated. However, it is not limited to these. Preferably, the optical film (first optical film or second optical film) is a polarizing plate. The polarizing plate will be described below.

〔Polarizer〕
In the present invention, a polarizing plate suitable as an optical film is produced by a conventionally known method by laminating a protective film and a polarizer with an adhesive and heating and drying or curing with ultraviolet rays, an electron beam or the like. be able to. The applied adhesive expresses adhesiveness by being dried or cured by ultraviolet rays, electron beams or the like to form an adhesive layer.

The polarizer is not particularly limited, and conventionally known ones can be used. For example, a dichroic material such as iodine or a dichroic dye is adsorbed onto a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene/vinyl acetate copolymer partially saponified film. Uniaxially stretched film, polyene oriented film such as polyvinyl alcohol dehydrated product, polyvinyl chloride dehydrochlorinated product, and the like.

Among these, a polarizer produced by dyeing a polyvinyl alcohol film having an average degree of polymerization of 2000 or more and 2800 or less and a saponification degree of 90 mol% or more and 100 mol% or less with iodine and uniaxially stretching it to 3 times or more and 8 times or less is particularly preferable. .. More specifically, such a polarizer is obtained by, for example, immersing a polyvinyl alcohol film in an aqueous solution of iodine, dyeing it, and stretching it.

As a method of immersing in an aqueous solution of iodine, it is preferable to immerse in an aqueous solution containing iodine and/or potassium iodide having a concentration of 0.1% by mass or more and 10% by mass or less. Further, if necessary, it may be immersed in an aqueous solution of boric acid or potassium iodide at 50° C. or higher and 70° C. or lower. Good. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. After dyeing and stretching, it may be washed with water if necessary and dried at 35° C. or higher and 55° C. or lower for about 1 minute to 10 minutes. A wide variety of such polarizers are also available as commercial products.

The thickness of the polarizer is not particularly limited, but is generally 3 μm or more and 80 μm or less.

In the present invention, a polarizing plate having one side or both sides protected is preferable as the optical film from the viewpoint that higher durability is required as the optical film. More preferably, it is a polarizing plate with one side protected (single-sided protective polarizing plate). The protection method is not particularly limited, and a known method such as attaching a protective film can be appropriately adopted.

As the protective film, a material having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. is preferable. For example, acrylic resin, cellulose resin such as triacetyl cellulose, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, polymethylmethacrylate and the like ( Examples thereof include (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, epoxy resins, and mixtures thereof.

A transparent protective film is attached to one side of the polarizer with an adhesive. However, on the other side, a transparent protective film or a (meth)acrylic, urethane, acryl urethane, epoxy, silicone or other thermosetting resin or ultraviolet curable resin can be used as a protective layer.

The thickness of the polarizing plate is not particularly limited and is generally 20 μm or more and 200 μm or less, but it is preferably 100 μm or less from the viewpoint of thinning. Such a thin polarizing plate is preferable from the viewpoint that the effect of the pressure-sensitive adhesive of the present invention is more remarkably exhibited.

The method for producing the polarizing plate is not particularly limited, and examples thereof include a method in which an adhesive is applied and then the polarizer and the protective film are bonded together by a roll laminator or the like. After bonding, a drying process or a curing process using ultraviolet rays, electron beams, or the like may be appropriately performed. When the adhesive is applied, it may be applied to either the protective film or the polarizer, or may be applied to both. The adhesive is preferably applied so that the thickness of the adhesive layer after drying is 10 nm or more and 10 μm or less. The adhesive is not particularly limited and may be appropriately selected from known ones according to the material of the polarizer. For example, when a polyvinyl alcohol-based film is used as the polarizer, a polyvinyl alcohol-based adhesive or an ultraviolet-curable adhesive may be acrylic, epoxy, or acryl-epoxy adhesive. The thickness of the adhesive layer is preferably 10 nm or more and 200 nm or less for the polyvinyl alcohol-based adhesive in order to obtain a uniform in-plane thickness and a sufficient adhesive force. In the case of an ultraviolet curable adhesive, it is preferably 0.2 μm or more and 10 μm or less.

In the present invention, a pressure-sensitive adhesive type polarizing plate having a pressure-sensitive adhesive layer formed thereon can be provided. Note that the configuration and manufacturing method of the pressure-sensitive adhesive type polarizing plate are the same as those of the optical film having the pressure-sensitive adhesive layer described above, and therefore the description thereof is omitted here.

[Image display device]
The present invention also provides an image display device using at least one of the above-mentioned optical members.

The image display device is not particularly limited, and examples thereof include a liquid crystal display device, an organic EL display device, a plasma display (PDP), and a micro LED display. Further, from the viewpoint of more remarkably exhibiting the effect of the pressure-sensitive adhesive for an optical film of the present invention, a particularly thin image display device is preferably applied.

The present invention will be described in more detail with reference to the following examples and comparative examples, but the technical scope of the present invention is not limited to the following examples.

In addition, in the following operations, unless otherwise specified, operations and measurements of physical properties were performed under conditions of 23° C. and relative humidity of 55% RH.

(Measurement of weight average molecular weight (Mw) of (meth)acrylic acid ester copolymer (A))
The weight average molecular weight of each (meth)acrylic acid ester copolymer (A) prepared in the following production example was measured by gel permeation chromatography (GPC) (see the following for measurement conditions):
・Analyzer: Tosoh Corporation, HLC-8120GPC
・Column: Tosoh Corporation, G7000HXL+GMHXL+GMHXL
・Column size: Each 7.8 mmφ×30 cm, total 90 cm
・Column temperature: 40℃
・Flow rate: 0.8 ml/min
・Injection volume: 100 μl
・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI)
-Standard sample: polystyrene.

(Measurement of weight average molecular weight (Mw) of silicate oligomer (F))
The weight average molecular weight of the silicate oligomer (F) used in the following examples was measured by gel permeation chromatography (GPC) (see the following for measurement conditions):
・Analyzer: Tosoh Corporation, HLC-8120GPC
・Column: TSKgel Super HZM-H/HZ4000/HZ2000
-Column size: 6.0 mmI. D. ×150 mm
・Column temperature: 40℃
・Flow rate: 0.6 ml/min
・Injection volume: 20 μl
・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI)
-Standard sample: polystyrene.

(Calculation of glass transition temperature (Tg) of (meth)acrylic acid ester copolymer (A))
The glass transition temperature of the (meth)acrylic acid ester copolymer (A) was calculated from the glass transition temperature of the homopolymer of the monomers constituting the polymer and the content ratio thereof by the following Fox equation:
Fox's formula: 1/Tg=(w1/Tg1)+(w2/Tg2)+...+(wn/Tgn)
Tg: Glass transition temperature (K) of polymer
Tgn, Tg2,... Tgn: glass transition temperature (K) of homopolymer of each monomer
w1, w2,... Wn: Weight fraction of each monomer.

(Preparation of single-sided protective polarizing plate)
A polyvinyl alcohol film having a thickness of 45 μm was stretched up to 3 times while being dyed for 1 minute in an iodine solution having a concentration of 0.3 mass% at 30° C. between rolls having different speed ratios. Then, the film stretched up to 3 times was immersed in an aqueous solution containing 60° C., 4% by mass concentration of boric acid, and 10% by mass concentration of potassium iodide for 0.5 minutes until the total stretching ratio became 6 times. It was stretched. Then, the film stretched up to 6 times was washed by immersing it in an aqueous solution containing potassium iodide having a concentration of 1.5% by mass at 30° C. for 10 seconds, and then dried at 50° C. for 4 minutes to obtain a polarizer. It was A uniaxially stretched PET film (Cosmoshine (registered trademark) super birefringence type (SRF) PET film manufactured by Toyobo Co., Ltd.) having a thickness of 80 μm was attached to one surface of the polarizer with a polyvinyl alcohol-based adhesive to give a total thickness. A thin polarizing plate having a surface area of 98 μm and being protected on one side (also simply referred to as a single sided protective polarizing plate) was produced.

[Production Example 1: Preparation of solution of (meth)acrylic acid ester copolymer (A1)]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 50 parts by mass of n-butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 2-ethylhexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 29 parts by mass, 2-methoxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 2-ethylhexyl-diglycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) 10 parts by mass, 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 1 Part by mass, and 0.1 part by mass of 2,2′-azobisisobutyronitrile (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) as a polymerization initiator are charged together with 100 parts by mass of ethyl acetate, while gently stirring. Nitrogen gas was introduced. After substituting with nitrogen gas, the liquid temperature in the flask was raised until ethyl acetate was refluxed, a polymerization reaction was carried out for 5 hours, and a (meth)acrylic acid ester copolymer (A1) having a weight average molecular weight (Mw) of 1250,000 was obtained. Was prepared.

[Production Examples 2 to 15: Preparation of solutions of (meth)acrylic acid ester copolymers (A2) to (A15)]
Production Example 1 except that the type and composition ratio of each monomer forming the (meth)acrylic acid ester copolymer were changed as shown in Table 1 below, and the amount of the polymerization initiator and the reaction time were changed appropriately. The same operation as above was performed to prepare solutions of (meth)acrylic acid ester copolymers (A2) to (A15). Table 1 also shows the glass transition temperatures (Tg) and weight average molecular weights (Mw) of the (meth)acrylic acid ester copolymers (A1) to (A15). The blank column in Table 1 indicates that the monomer was not used.

<Example 1>
[Preparation of pressure-sensitive adhesive for optical film]
Crosslinked to 100 parts by mass of the solid content of the (meth)acrylic acid ester copolymer (A1) solution obtained in Production Example 1 (that is, 100 parts by mass of the (meth)acrylic acid ester copolymer (A1)). Takenate (registered trademark) D-110N (75 wt% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate as one agent (B) in ethyl acetate, number of isocyanate groups in one molecule: 3, manufactured by Mitsui Chemicals, Inc.) 1 part by mass (Active ingredient conversion), and 0.1 parts by mass of KBM-403 (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (C) are mixed with stirring to prepare an optical film. An adhesive (solid content 25% by mass) was prepared.

[Formation of adhesive layer]
The pressure-sensitive adhesive for an optical film obtained above was applied to one side of a 38 μm-thick polyethylene terephthalate (PET) film (Mitsubishi Chemical Co., Ltd., MRF38, no oligomer-preventing layer) which had been subjected to a silicone treatment, after drying. It was applied so that the layer thickness was 25 μm. Then, it heat-processed at 110 degreeC for 4 minute(s), and formed the adhesive layer of Example 1. The heat treatment was performed by a float drying method in which hot air was blown directly from above and below the film.

[Preparation of optical member (single-sided protective polarizing plate with adhesive layer)]
Corona treatment was performed on the side of the polarizer forming the pressure-sensitive adhesive layer of the above single-sided protective polarizing plate with a corona discharge amount of 80 [W·min/m ² ]. Then, the pressure-sensitive adhesive layer formed on the above-mentioned silicone-treated PET film was transferred onto the surface of the corona-treated polarizer to prepare an optical member (one-sided protective polarizing plate with a pressure-sensitive adhesive layer). did.

<Examples 2 to 19 and Comparative Examples 1 to 5>
As shown in Table 2 below, a (meth)acrylic acid ester copolymer (A), a cross-linking agent (B), a silane coupling agent (C), a silicate oligomer (D), which constitutes the pressure-sensitive adhesive for an optical film, Examples 2 to 19 and 2 to 19 in the same manner as in Example 1 except that the type and addition amount (blending amount) of the softening point resin (E) and the (meth)acrylic (co)polymer (F) were changed. Optical members (single-sided protective polarizing plates with pressure-sensitive adhesive layers) corresponding to Comparative Examples 1 to 5 were produced.

In Table 2 above,
1. The addition amount (unit: parts by mass) of the components (B), (C), (D), (E), and (F) represents the addition amount when the copolymer (A) is 100 parts by mass. 2. "-" in the table indicates that the component is not blended. “D-110N”: a product manufactured by Mitsui Chemicals, Inc. (Takenate (registered trademark) D-110N, a 75 wt% ethyl acetate solution of a trimethylolpropane adduct of xylylene diisocyanate, the number of isocyanate groups in one molecule: 3) 3. “P-6090”: a product manufactured by Sanyo Kasei Co., Ltd. (Samprene (registered trademark) P-6090, a prepolymer having isocyanate groups at both ends reacted with polytetramethylene ether glycol and diphenylmethane diisocyanate, NCO%: 7 6%) 5. “TCP”: a product manufactured by NOF CORPORATION (Perloyl (registered trademark) TCP, bis(4-t-butylcyclohexyl)peroxydicarbonate) 6. “KBM-403”: a product of Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltrimethoxysilane) 7. “KBE-403”: a product of Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltriethoxysilane) 8. “Methyl silicate 53A”: a product (trade name: methyl silicate 53A) manufactured by Colcoat Co., Ltd. 9. “KE-100”: a product manufactured by Arakawa Chemical Industry Co., Ltd. (pine crystal KE-100, softening point 95-105° C. (ring and ball method), ultra-light color rosin derivative) 10. “A-75”: a product manufactured by Arakawa Chemical Industries, Ltd. (super ester A-75, softening point 70-80° C. (ring and ball method), special rosin ester) 11. "Tamanor 460": a product (softening point 182-192°C (ring and ball method), rosin-modified phenolic resin) manufactured by Arakawa Chemical Co., Ltd. 12. “UH-2170”: a product manufactured by Toagosei Co., Ltd. (Alfon (registered trademark) UH-2170, solvent-free styrene acrylic polymer, weight average molecular weight (Mw) 14,000, glass transition temperature (Tg) 60° C.) is there.

[Evaluation]
The following evaluations were performed on the pressure-sensitive adhesives for optical films produced in Examples 1 to 19 and Comparative Examples 1 to 5 and the pressure-sensitive adhesive layer-attached single-sided protective polarizing plate (sample) that is an optical member.

<Air bubbles at the end>
The optical member (single-sided protective polarizing plate with an adhesive layer) produced in each of Examples 1 to 19 and Comparative Examples 1 to 5 was cut out to a 37-inch size as a sample, and a 0.7 mm-thick non-alkali glass (Corning Co., Ltd. was used. Manufactured by Eagle XG) using a laminator. Then, the sample was autoclaved at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to acrylic-free glass. The samples subjected to such treatment were subjected to the durability tests (1) and (2) below, and after each test, the appearance between the polarizing plate and the glass was visually evaluated according to the following criteria. In this evaluation, bubbles generated within 1 mm on both ends of the polarizing plate on the stretching direction side were observed:
(1) Treated at 85°C for 500 hours (heating test)
(2) After being left in an environment of 85° C. for 30 minutes and then left in an environment of −40° C. for 30 minutes as one cycle (1 hour), a total of 300 cycles (300 hours) were performed (heat shock (HS) test). ..

Visual evaluation ◎: No air bubbles newly generated at the end ○: There are a few air bubbles generated at the end, but there is no problem in practical use △: There are air bubbles at the end, but if there is no special use, No problem in practical use x: There is a problem in practical use because there are a significant number of bubbles at the edges.

<Warp>
The optical member (single-sided protective polarizing plate with the pressure-sensitive adhesive layer) produced in each of Examples 1 to 19 and Comparative Examples 1 to 5 was cut into a size of 100 mm in length×50 mm in width to obtain a sample. This sample was adhered to a non-alkali glass (Eagle XG, manufactured by Corning Incorporated) having a length of 75 mm × a width of 150 mm × a thickness of 0.5 mm by using a laminator. Then, the sample was autoclaved at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to acrylic-free glass. The sample thus treated was further subjected to heat treatment at 85° C. for 100 hours. Then, after leaving it for 1 hour under the condition of 25°C and relative humidity 55%RH, place it on a horizontal surface so that the surface with the convex warp is on the lower side. The distance (mm) at a long point from the horizontal plane was measured. The evaluation criteria are as follows:
-Evaluation criteria-
⊚: Warpage amount of 0 mm or more and less than 0.5 mm O: Warpage amount of 0.5 mm or more and less than 1.0 mm B: Warpage amount of 1.0 mm or more and less than 1.5 mm X: Warpage amount of 1.5 mm or more

<Scratch>
An optical member (adhesive layer-attached one-sided protection) immediately after coating (immediately after transferring a PET film having an adhesive layer formed thereon; within 10 minutes after transfer) produced in Examples 1 to 19 and Comparative Examples 1 to 5 above. The polarizing plate) was cut into a size of 100 mm long×100 mm wide to prepare 300 pieces of sample pieces (samples) in total. These sample pieces were stacked with the PET film (protective film) surface of the polarizing plate (the protective film surface on the side where the adhesive layer is not formed) facing up. A weight of 1 kg was applied from the top, the plate was left for 1 day under the condition of 23° C. and a relative humidity of 50% RH, and the depth of occurrence of a dent was evaluated by a laser microscope (VK-X120) manufactured by Keyence Corporation. The evaluation criteria are as follows:
-Evaluation criteria-
⊚: dent depth 0 μm or more and less than 1 μm ◯: dent depth 1 μm or more and less than 3 μm Δ: dent depth 3 μm or more and less than 5 μm ×: dent depth 5 μm or more

<Durability>
The optical member (single-sided protective polarizing plate with an adhesive layer) produced in each of Examples 1 to 19 and Comparative Examples 1 to 5 was cut out to a 37-inch size as a sample, and a 0.7 mm-thick non-alkali glass (Corning Co., Ltd. was used. Manufactured by Eagle XG) using a laminator. Then, the sample was autoclaved at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to acrylic-free glass. The samples subjected to such treatment were subjected to the durability tests (1) to (3) below, and after each test, the appearance between the polarizing plate and the glass was visually evaluated according to the following criteria. In this evaluation, the entire polarizing plate was visually observed:
(1) Treated at 85°C for 500 hours (heating test)
(2) Treated for 500 hours in an atmosphere of 60° C./95% relative humidity (humidification test)
(3) After being left in an environment of 85° C. for 30 minutes and then left in an environment of −40° C. for 30 minutes as one cycle (1 hour), a total of 300 cycles (300 hours) were performed (heat shock (HS) test). ..

Visual evaluation ◎: No change in appearance such as foaming, peeling, floating, etc. ○: Peeling or foaming at a slight edge, but no problem in practical use △: Peeling or foaming at the edge, There is no problem in practical use unless it is a special use. x: There is significant peeling at the end, which is a problem in practical use.

<Reworkability>
The optical member produced in each of Examples 1 to 19 and Comparative Examples 1 to 5 was cut into a width of 25 mm and a length of 100 mm to be Sample 1, and a piece to be cut in a length of 420 mm and a width of 320 mm was called Sample 2 (three sheets were prepared). did. Each of Sample 1 and Sample 2 was attached to a 0.7 mm-thick non-alkali glass plate (Eagle XG, manufactured by Corning Incorporated) using a laminator. Then, autoclave treatment was performed at 50° C. and 506.5 kPa (5 atm) for 15 minutes for complete contact (initial stage). Then, it heat-processed for 48 hours on the dry condition of 50 degreeC (after heating).

The adhesive strength of the sample 1 was measured at the initial stage and after heating. The adhesive force is measured by a tensile tester (manufactured by Orientec Co., Ltd., Tensilon universal material tester, STA-1150) under the conditions of 23° C. and relative humidity of 50% RH under a peeling angle of 180° and a peeling speed of 300 mm/min. It was determined by measuring the adhesive force (N/25 mm) when the sample 1 was peeled off according to the method of the adhesive tape and adhesive sheet test of JIS Z0237 (2009).

Further, with respect to the sample 2 (3 pieces), the sample was peeled from the alkali-free glass plate by a human hand, and the reworkability was evaluated according to the following criteria (actual reworkability):
Evaluation Criteria ⊚: All three sheets can be peeled off well without adhesive residue or breakage of the film. ○: Part of the three sheets broke the film, but could be peeled off by peeling again. Peeling was possible by peeling again. ×: Adhesive residue was generated on all three sheets, or the film was broken and could not be peeled off no matter how many times it was peeled off.

The evaluation results are shown in Table 3 below.

As is clear from Table 3 above, the single-sided protective polarizing plates with pressure-sensitive adhesive layers produced using the pressure-sensitive adhesives for optical films of Examples 1 to 19 were used in harsh environments (high temperature, high humidity, heat shock). Durability (particularly, suppression of bubbles generated at the ends of the polarizing plate and suppression of peeling of the polarizing plate) was improved. It was also found that both warpage and dents can be suppressed, and reworkability (workability) is also excellent.

On the other hand, in the one-sided protective polarizing plates with pressure-sensitive adhesive layers of Comparative Examples 1 and 3, peeling of the polarizing plate occurred in the warp test, and evaluation of air bubbles at the edges could not be performed. In the pressure-sensitive adhesive of Comparative Example 2, the Mw of the copolymer (A) was too high and gel was generated, so that an evaluation sample could not be prepared. The one-sided protective polarizing plate with the pressure-sensitive adhesive layer of Comparative Example 4 deteriorated in end air bubbles, and the one-sided protective polarizing plate with the pressure-sensitive adhesive layer of Comparative Example 5 could not suppress dents.

Claims (28)

A pressure-sensitive adhesive for an optical film, comprising a (meth)acrylic acid ester copolymer (A),
The (meth)acrylic acid ester copolymer (A) is
(A1) a structural unit derived from a (meth)acrylic acid alkyl ester monomer: 10% by mass or more and 95% by mass or less;
(A2) a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkoxyalkyl group or an alkoxyalkylene glycol group, 5% by mass or more and 90% by mass or less;
(A3) A structural unit derived from a functional group-containing monomer that is a (meth)acrylic acid derivative monomer having one radically polymerizable functional group, in excess of 0% by mass and 20% by mass or less;
(However, the total amount of the structural units derived from the above (a1), (a2), and (a3) is 100% by mass.
Including,
The (meth)acrylic acid ester copolymer (A) has a glass transition temperature of higher than −55° C. and −50° C. or lower, and a weight average molecular weight of 700,000 or more and 2,000,000 or less. .. The (meth)acrylic acid ester copolymer (A) further contains a structural unit derived from the monomer (a4) other than the (a1), the (a2), and the (a3),
The content of the structural unit derived from the monomer (a4) is 0.01 parts by mass or more and 10 parts by mass with respect to 100 parts by mass in total of the structural units derived from the (a1), the (a2), and the (a3). The adhesive for optical films according to claim 1, which is less than or equal to 1 part. The pressure-sensitive adhesive for an optical film according to claim 1, wherein the (meth)acrylic acid ester copolymer (A) has a weight average molecular weight of more than 1 million and not more than 1.5 million. The carbon number of the alkoxy group which the said (a2) alkoxyalkyl group or the (meth)acrylic acid alkyl ester monomer which has an alkoxyalkylene glycol group has is 2 or more and 18 or less. Adhesive for optical films. The functional group-containing monomer, which is the (meth)acrylic acid derivative monomer having one (a3) radically polymerizable functional group, has a hydroxy group, an acyl group or an epoxy group, or a (meth)acrylic acid ester monomer or (meth)acrylamide. The pressure-sensitive adhesive for an optical film according to any one of claims 1 to 4, which is a monomer. The pressure-sensitive adhesive for an optical film according to any one of claims 1 to 5, wherein the alkyl group of the (meth)acrylic acid alkyl ester monomer (a1) has 1 to 18 carbon atoms. Content of the structural unit derived from the said (a1) (meth)acrylic acid alkyl ester monomer is 15 mass% or more and 80 mass% or less, The adhesive agent for optical films of any one of Claims 1-6. .. The pressure-sensitive adhesive for optical films according to any one of claims 1 to 7, wherein the (meth)acrylic acid ester copolymer (A) contains a hydroxy group. The pressure-sensitive adhesive for an optical film according to claim 1, further comprising a cross-linking agent (B). The optical film according to claim 9, wherein the crosslinking agent (B) is contained in an amount of 0.001 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic acid ester copolymer (A). Adhesive. The cross-linking agent (B) is at least one selected from the group consisting of isocyanate compounds, carbodiimide compounds, oxazoline compounds, epoxy compounds, polyfunctional acrylic acid ester monomers, and peroxides. The pressure-sensitive adhesive for an optical film described. Any one of Claims 1-11 which further contains 0.001 mass part or more and 5 mass parts or less of silane coupling agents (C) with respect to 100 mass parts of said (meth)acrylic acid ester copolymer (A). The pressure-sensitive adhesive for an optical film according to item 1. The pressure-sensitive adhesive for an optical film according to claim 1, further comprising a silicate oligomer (D) represented by the following chemical formula 4:
In the above chemical formula 4,
R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group;
X ¹ and X ² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group;
n is an integer of 1 or more and 100 or less. The pressure-sensitive adhesive for an optical film according to claim 13, wherein the silicate oligomer (D) contains a methyl silicate oligomer. The pressure-sensitive adhesive for an optical film according to claim 13 or 14, wherein the silicate oligomer (D) has a weight average molecular weight of 300 or more and 30,000 or less. 16. The optical film according to claim 9, wherein the crosslinking agent (B) contains an isocyanate compound having a number average molecular weight of 900 or more and 10,000 or less (excluding a blocked isocyanate compound). Adhesive. The pressure-sensitive adhesive for optical films according to claim 1, further comprising a high softening point resin (E). The pressure-sensitive adhesive for an optical film according to claim 17, wherein the high softening point resin (E) is a rosin ester resin. The homopolymer contains a structural unit derived from a (meth)acrylic monomer having a glass transition temperature of 50° C. or higher, and has a smaller weight average molecular weight (Mw) than the (meth)acrylic acid ester copolymer (A) (meta). ) The pressure-sensitive adhesive for an optical film according to any one of claims 1 to 18, further comprising an acrylic (co)polymer (F). The pressure-sensitive adhesive for an optical film according to claim 19, wherein the (meth)acrylic (co)polymer (F) has a weight average molecular weight (Mw) of 500 or more and 100,000 or less. A pressure-sensitive adhesive layer for an optical film, which is formed from the pressure-sensitive adhesive for an optical film according to claim 1. An adhesive layer for an optical film according to claim 21,
A first optical film provided on one surface of the pressure-sensitive adhesive layer,
And an optical member. 23. The optical member according to claim 22, further comprising glass or a second optical film on the surface of the pressure-sensitive adhesive layer opposite to the surface on which the first optical film is provided. The optical member according to claim 22 or 23, further comprising at least one easy-adhesion treated layer between the first optical film and the pressure-sensitive adhesive layer for an optical film. The easy adhesion treatment layer has a first easy adhesion treatment layer and a second easy adhesion treatment layer,
The optical member, the first optical film, the first easy adhesion treatment layer, the second easy adhesion treatment layer, and the pressure-sensitive adhesive layer for the optical film are laminated in this order, 25. The optical member described. An image display device using at least one optical member according to any one of claims 22 to 25. A pressure-sensitive adhesive layer for an optical film, which comprises applying the pressure-sensitive adhesive for an optical film according to any one of claims 1 to 20 onto a release sheet subjected to a release treatment, and then subjecting it to a heat treatment to cause a crosslinking reaction. Production method. The method for producing a pressure-sensitive adhesive layer for an optical film according to claim 27, wherein the temperature of the heat treatment is 80°C or higher and 120°C or lower.