JP7149067B2 - PSA COMPOSITION FOR OPTICAL FILM, ADHESIVE LAYER, OPTICAL MEMBER, AND IMAGE DISPLAY DEVICE - Google Patents

Description

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

Liquid crystal panels such as liquid crystal display devices, which are a type of image display device, are affixed with optical members such as various optical films to improve the display quality of the display, in addition to the indispensable polarizing film (polarizing plate). It is A pressure-sensitive adhesive is usually used when attaching an optical member such as an optical film to a liquid crystal panel, or when attaching two or more optical films of the same type or different types.

The required properties of the adhesive are the durability of the adhesive in its adhered state, such that problems such as peeling and lifting due to the adhesive do not occur in durability tests such as heat and humidification, which are usually conducted as environmental accelerated tests. is required. Especially in recent years, there is a demand for optical films used in automotive panels that do not cause problems such as foaming or peeling caused by adhesives in durability tests under higher temperature and humidity environments than before. ing.

Also, when using an adhesive to attach the optical film to the LCD panel, if the location of the attachment is incorrect or foreign matter is caught in the attachment surface, the optical film should be peeled off from the LCD panel. Then, it is necessary to perform bonding again. In particular, in recent years, in addition to the manufacturing process of conventional liquid crystal display devices, the use of liquid crystal display devices such as thin liquid crystal panels using chemically etched glass is increasing, and optical films are becoming thinner and more fragile. . If a conventional pressure-sensitive adhesive that aims only for durability is used for such a thin liquid crystal display device or thin optical film, the thin liquid crystal display device or thin optical film will crack or break. I have a problem. For this reason, in the peeling process, adhesives are required to have re-peelability (also referred to as "reworkability"), which allows the optical film to be easily peeled off from liquid crystal display devices and the like without leaving adhesive residue. ing. In addition, in thin liquid crystal panels, there is a problem that the optical film expands or contracts due to heating, humidification, or the like, causing the liquid crystal panel to warp and come into contact with the frame, resulting in deterioration of display quality. . However, if the stress relaxation property of the pressure-sensitive adhesive is increased in order to reduce the expansion or contraction of the optical film due to heating, humidification, etc., workability and dents will be deteriorated, and the defect rate in the process will be deteriorated.

In addition, pressure-sensitive adhesive optical films used in highly versatile products such as televisions (TVs) are required to further reduce manufacturing costs, and it has become necessary to increase the line speed of pressure-sensitive adhesive production. ing. In this way, it is possible to simultaneously suppress warping and dents while ensuring workability, have high durability and reworkability, and have excellent handling properties in the manufacturing process. There is a demand for an optical film pressure-sensitive adhesive from which a film can be obtained.

As such an adhesive, for example, Patent Document 1 discloses an acrylic polymer having a weight average molecular weight of 500,000 or more and 1,000,000 or less, which is obtained by copolymerizing n-butyl acrylate, a hydroxyl group-containing monomer, and other monomers. and a pressure-sensitive adhesive composition for optical members containing the acrylic polymer, a radical generator, an isocyanate cross-linking agent, and a silane coupling agent, wherein the solid content is 25% by weight or more and the solvent is 75 % by weight or less and having a viscosity of 8 Pa·s or less with a Brookfield viscometer at 100 rpm at 23°C.

Further, Patent Document 2 discloses a pressure-sensitive adhesive composition for an optical film containing a (meth)acrylic polymer and a solvent, wherein the (meth)acrylic polymer does not contain a carboxyl group-containing monomer as a monomer unit, An alkyl (meth)acrylate, a polymerizable aromatic ring-containing monomer, and a hydroxyl group-containing monomer are copolymerized, and have a weight average molecular weight of 300,000 to 1,200,000, and contain a solid content containing the (meth)acrylic polymer. Compositions are disclosed in which the amount of solvent is greater than or equal to 20% by weight and the content of said solvent is less than or equal to 80% by weight.

Furthermore, Patent Document 3 discloses a pressure-sensitive adhesive composition for an optical film containing a (meth)acrylic polymer and a solvent, wherein the (meth)acrylic polymer is an alkyl (meth)acrylate and a polymerizable aromatic ring-containing monomer. , a hydroxyl group-containing monomer, and a carboxyl group-containing monomer, have a weight average molecular weight of 300,000 to 1,200,000, and have a solid content of 20% by weight or more including the (meth)acrylic polymer. A composition is disclosed in which the solvent content is 80% by weight or less.

JP 2011-057794 A JP 2012-140578 A JP 2012-140579 A

However, according to the studies of the present inventors, even with the adhesive compositions described in Patent Documents 1 to 3, durability (high temperature It has been found that the foaming resistance at high temperature, lifting and peeling from the adherend under high temperature and high humidity) and reworkability (processability) are not sufficient, and light leakage may occur. Furthermore, in addition to the case where the durability, reworkability, and light leakage are not sufficient, it has been found that the occurrence of warpage and dents cannot be suppressed in some cases.

The present invention has been made in view of the above circumstances, and in the pressure-sensitive adhesive composition for optical films, after ensuring processability, durability in harsh environments (high temperature, high humidity, heat shock) (high temperature In addition to improving foaming resistance at high temperature and high humidity, and reworkability (processability), light leakage is sufficiently suppressed, and warp and dent It aims at providing the means which can suppress both.

Means for Solving the Problems As a result of intensive studies aimed at solving the above problems, the present inventors have found that the above problems can be solved by a pressure-sensitive adhesive composition having a specific configuration, and have completed the present invention.

That is, the present invention provides a (a1) structural unit derived from an alkyl (meth)acrylate monomer, and (a2) a (meth)acrylate having 0.01 to 10% by mass of a hydroxyl group relative to 100% by mass of the total amount of structural units. At least one structural unit selected from the group consisting of a structural unit derived from a monomer and a structural unit derived from a monomer having a (a3) carboxyl group in an amount of 0.01 to 7% by mass relative to 100% by mass of the total amount of structural units. A (meth)acrylate copolymer (A), a polyrotaxane compound (B) having as a cyclic molecule a cyclic oligosaccharide having a hydroxyl group as a reactive group, a cross-linking agent (C), and a solvent (D), comprising wherein the (meth)acrylate copolymer (A) has a weight average molecular weight of 300,000 or more and 1,200,000 or less by gel permeation chromatography (GPC); The solid content containing the (meth)acrylate copolymer (A) in the adhesive composition is 20% by mass or more with respect to the total mass of the optical film adhesive composition, and the optical film The content of the solvent (D) in the pressure-sensitive adhesive composition is 80% by mass or less with respect to the total weight of the pressure-sensitive adhesive composition for optical films, and the B-type viscometer of the pressure-sensitive adhesive composition for optical films The pressure-sensitive adhesive composition for an optical film has a viscosity of 200 mPa·s or more and 5000 mPa·s or less at 23° C. (rotation speed: 20 rpm).

According to the present invention, in the pressure-sensitive adhesive composition for optical films, after ensuring workability, durability in harsh environments (high temperature, high humidity, heat shock) (foaming resistance at high temperature, high temperature and high humidity It is possible to improve reworkability (processability), sufficiently suppress light leakage, and further suppress both warpage and dents. .

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated.

[Adhesive composition for optical film]
The pressure-sensitive adhesive composition for an optical film of the present invention comprises (a1) structural units derived from alkyl (meth)acrylate monomers, and 0.01 to 10% by weight of (a2) hydroxyl groups relative to 100% by weight of the total amount of structural units. Structural units derived from (meth) acrylate monomers having and 0.01 to 7% by weight of the total amount of structural units 100% by weight (a3) selected from the group consisting of structural units derived from monomers having a carboxyl group a (meth)acrylate copolymer (A), a polyrotaxane compound (B) having as a cyclic molecule a cyclic oligosaccharide having a hydroxyl group as a reactive group, a cross-linking agent (C), and A pressure-sensitive adhesive composition for an optical film containing a solvent (D), wherein the (meth)acrylate copolymer (A) has a weight-average molecular weight determined by gel permeation chromatography (GPC) of 300,000 or more and 1,200,000 or less. and the solid content containing the (meth)acrylate copolymer (A) in the pressure-sensitive adhesive composition for optical films is 20% by mass or more with respect to the total mass of the pressure-sensitive adhesive composition for optical films. and the content of the solvent (D) in the pressure-sensitive adhesive composition for optical films is 80% by mass or less with respect to the total weight of the pressure-sensitive adhesive composition for optical films, and the pressure-sensitive adhesive composition for optical films The viscosity at 23° C. measured by a B-type viscometer (rotation speed 20 rpm) is 200 mPa·s or more and 5000 mPa·s or less.

According to the pressure-sensitive adhesive composition for an optical film of the present invention having such a configuration, workability is ensured, and durability (foaming resistance at high temperature) under harsh environments (high temperature, high humidity, heat shock) In addition to improving reworkability (processability), light leakage is sufficiently suppressed, and both warping and dents are suppressed. be able to.

Each component constituting the pressure-sensitive adhesive composition for an optical film according to the present invention will be described below in order.

In this specification, "(meth)acrylate" is a generic term for acrylate and methacrylate. Similarly, compounds containing (meth) such as (meth)acrylic acid are collective names for compounds having "meta" in their names and compounds not having "meta" in their names. The "(meth)acrylate copolymer (A)" is also referred to as "copolymer (A)".

<(Meth)acrylate copolymer (A)>
The pressure-sensitive adhesive composition for an optical film according to the present invention essentially contains a (meth)acrylate copolymer (A). The copolymer (A) reacts with the cross-linking agent (C) together with the polyrotaxane compound (B) to form a cross-linked structure, thereby exhibiting adhesiveness (adhesiveness).

The weight average molecular weight (Mw) of the copolymer (A) according to the present invention by gel permeation chromatography (GPC) is 300,000 or more and 1,200,000 or less. When the weight-average molecular weight (Mw) is less than 300,000, dents are generated, and durability at high temperatures and reworkability after heating are deteriorated. On the other hand, when it exceeds 1,200,000, warping occurs.

The weight average molecular weight (Mw) of the copolymer (A) by gel permeation chromatography (GPC) is preferably 300,000 or more and less than 1,000,000, more preferably 400,000 or more and 950,000 or less, and 50 It is more preferably 10,000 or more and 900,000 or less. When the Mw of the copolymer (A) is within the above range, the molecular weight of the component (A) is small by adjusting the solid content and the solvent content of the component (A), and further by adjusting the viscosity of the pressure-sensitive adhesive composition. By cross-linking the polyrotaxane compound (B) with the cross-linking agent (C) to form a network and apply a network (to form a network structure), conventionally, when using the low molecular weight component (A) in the above range, the high temperature It was found that the polarizing plate peeled off as soon as the shrinkage of the polarizing plate increased in 1, but it was found that a special effect can be obtained in that the peeling becomes difficult. In addition, due to the effect of the low molecular weight of component (A), the effect of suppressing the occurrence of warpage is excellent, and the effect of suppressing the occurrence of dents is also excellent due to the presence of a network structure, although the molecular weight is low. In addition, due to the effect of reducing the molecular weight of component (A) and adjusting the viscosity, the effect of significantly improving productivity during coating is also excellent. In this way, it is preferable from the viewpoint of particularly excellent balance between the effect of suppressing the occurrence of warpage and dents, in addition to the effect of significantly improving the durability (peeling suppression effect) under harsh environments and the effect of greatly improving the productivity during coating. The weight average molecular weight (Mw) of the copolymer (A) of the present invention is appropriately adjusted by adjusting reaction conditions such as the type and/or amount of the polymerization initiator used in the polymerization reaction described later, the reaction temperature, and the reaction time. Therefore, a person skilled in the art can easily control it.

In addition, the number average molecular weight (Mn) of the copolymer (A) according to the present invention by gel permeation chromatography (GPC) is not particularly limited. In addition, from the viewpoint of particularly excellent balance between the effect of suppressing the occurrence of warping and dents, it is preferably 50,000 or more and 400,000 or less, more preferably 70,000 or more and 300,000 or less, and 80,000 or more and 200,000 or less. is particularly preferred. Further, the number average molecular weight (Mn) of the copolymer (A) of the present invention can be determined by those skilled in the art by appropriately adjusting the polymerization initiator used in the polymerization reaction described below, reaction conditions such as reaction temperature and reaction time, and the like. can be easily controlled.

In addition, the degree of dispersion (Mw/Mn) of the copolymer (A) according to the present invention is not particularly limited, but durability and reworkability are compatible, and the productivity during coating is greatly improved. In addition, from the viewpoint of a particularly excellent balance between the effects of suppressing the occurrence of warpage and dents, it is preferably 2.0 or more and 20 or less, more preferably 2.5 or more and 15 or less, and 3.0 or more and 10 or less. is particularly preferred.

The weight-average molecular weight (Mw), number-average molecular weight (Mn), and dispersity (Mw/Mn) of the copolymer (A) can be measured by gel permeation chromatography (GPC), and are described in detail. can be measured by the method shown in the examples.

In the present invention, as structural units constituting the copolymer (A),
(a1) A structural unit derived from an alkyl (meth)acrylate monomer (hereinafter also simply referred to as “component (a1)”), and (a2) a structural unit derived from a (meth)acrylate monomer having a hydroxyl group (hereinafter simply referred to as “component (a2)”) and (a3) a structural unit derived from a monomer having a carboxyl group (hereinafter also simply referred to as “component (a3)”). That is, the copolymer (A) according to the present invention preferably contains component (a1) and component (a2); it also preferably contains component (a1) and component (a3); It is also preferred to include component (a2) and component (a3).

In this 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 used when the copolymer X is obtained by copolymerization. It means that the monomer Y1 and the monomer _{Y2 are} included as raw material monomers.

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

[(a1) structural unit derived from alkyl (meth)acrylate monomer]
The copolymer (A) according to the present invention preferably contains (a1) a structural unit derived from an alkyl (meth)acrylate monomer (hereinafter also simply referred to as "component (a1)"). It is considered that such a component (a1) is significant in ensuring adhesiveness and basic properties by being included as a structural unit of the (meth)acrylate copolymer (A) according to the present invention.

In the present invention, the structure of the alkyl (meth)acrylate monomer is not particularly limited as long as it is a form in which an alkyl group is introduced into the ester site of (meth)acrylate.

The number of carbon atoms in the alkyl group is not particularly limited, but is preferably 1 to 20, more preferably 1 to 12, and 1 to 10 from the viewpoint of versatility, price, handling, etc. is more preferably 1 or more and 8 or less, and particularly preferably 1 or more and 6 or less. The alkyl group may be linear, branched, or cyclic, but is preferably linear or branched from the viewpoint of lowering the glass transition temperature. When the alkyl group is cyclic, it has 3 or more carbon atoms.

Examples of such alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, t-butyl, isobutyl, n-pentyl, isopentyl, n -hexyl group, 2-hexyl 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 , an isooctyl group, a t-octyl group, a 2-ethylhexyl group, a nonyl group, an isononyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a cyclohexyl group, or the like. mentioned. In particular, a methyl group, n-butyl group, n-hexyl group, 2-ethylhexyl group, nonyl group, and isononyl group are preferable from the viewpoint of ensuring adhesiveness and basic properties.

Thus, specific examples of alkyl (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, acrylates, 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. Among them, methyl (meth)acrylate and n-butyl (meth)acrylate are preferred from the viewpoint of improving heat durability and adhesive strength (especially reworkability). In addition, the component (a1) can be used alone or in combination of two or more.

The content of component (a1) in the copolymer (A) according to the present invention (amount of alkyl (meth)acrylate monomer blended as a raw material monomer) is not particularly limited, but the content of other raw material monomers described later and and from the viewpoint of improving durability, etc., 64.5% by mass or more and 99.5% by mass with respect to 100% by mass of the total amount of structural units constituting the (meth)acrylate copolymer (A) %, more preferably 80% by mass or more and 99% by mass or less, and particularly preferably 85% by mass or more and 99% by mass or less. In the present specification, "the total amount of the structural units constituting the (meth)acrylate copolymer (A) is 100% by mass" means that when the (meth)acrylate copolymer (A) is obtained by copolymerization, It means that the total amount of all raw material monomers used is 100% by mass.

[(a2) structural unit derived from (meth)acrylate monomer having hydroxyl group]
The copolymer (A) according to the present invention preferably contains (a2) a structural unit derived from a (meth)acrylate monomer having a hydroxyl group (hereinafter also simply referred to as "component (a2)"). Since such a component (a2) is highly reactive with a cross-linking agent, it is contained as a structural unit of the copolymer (A) according to the present invention, thereby improving the cohesiveness and heat resistance of the pressure-sensitive adhesive layer described later. It is considered to have significance to improve. In addition, according to the studies of the present inventors, the portion of the component (a2) of the copolymer (A) can react with the cross-linking agent (C) according to the present invention, and the cross-linking density of the pressure-sensitive adhesive layer described later is It was found that the rising pressure-sensitive adhesive layer becomes hard and the amount of deformation of the pressure-sensitive adhesive layer at the time of re-peeling is reduced, thereby lowering the adhesive strength, achieving desirable reworkability, and suppressing peeling in terms of durability. Furthermore, it was also found that by setting the weight average molecular weight of the copolymer (A) and the viscosity of the composition within the ranges of the present invention, it is possible to suppress the occurrence of warpage and dents.

In the present invention, the structure of the (meth)acrylate monomer having a hydroxyl group is not particularly limited as long as it is in a form in which a hydroxyl group is partially introduced into the (meth)acrylate monomer.

Specific examples of (meth)acrylate monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate. ) acrylate, dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylol ethane di (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, hydroxymethyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, cyclohexanedimethanol monoacrylate, etc. and furthermore, compounds obtained by the addition reaction of glycidyl group-containing compounds such as alkyl glycidyl ether, allyl glycidyl ether, glycidyl (meth)acrylate, and (meth)acrylic acid. Among them, from the viewpoint of efficiently functioning as a cross-linking point, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylamide, and cyclohexanedimethanol monoacrylate are preferable, and 2- Hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are more preferred. These components (a2) can be used alone or in combination of two or more.

When the copolymer (A) according to the present invention contains the component (a2), the content of the component (a2) (the amount of the (meth)acrylate monomer having a hydroxyl group as a raw material monomer) is It is 0.01% by mass or more and 10% by mass or less with respect to 100% by mass of the total amount of the structural units constituting A). If the content of component (a2) is less than 0.01% by mass, the number of cross-linking reaction points becomes too small, resulting in poor durability. On the other hand, if the content of the component (a2) exceeds 10% by mass, the ratio of the polar monomers to be blended becomes relatively large, and the polarity of the formed pressure-sensitive adhesive layer also becomes high, resulting in reduced durability. The content of component (a2) is preferably 0.3% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less.

[(a3) Structural Unit Derived from Monomer Having Carboxyl Group]
In the present invention, the copolymer (A) preferably contains (a3) a structural unit derived from a monomer having a carboxyl group (hereinafter also simply referred to as "component (a3)"). Such a component (a3) can mainly contribute to improvement of durability and reworkability in the pressure-sensitive adhesive composition for optical films.

In the present invention, the structure of the monomer having a carboxyl group is not particularly limited, and may have any structure as long as it contains a carboxyl group and a polymerizable unsaturated bond in its structure.

Specific examples of monomers having a carboxyl group include (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, itaconic anhydride, myristoleic acid, palmitoleic acid, and olein. acids and the like. Among them, (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, anhydride, from the viewpoint of excellent copolymerization with other (meth)acrylic monomers Itaconic acid is preferred, and (meth)acrylic acid is more preferred. These components (a3) can be used alone or in combination of two or more.

When the copolymer (A) according to the present invention contains the component (a3), the content of the component (a3) (the amount of the (meth)acrylate monomer having a hydroxyl group as a raw material monomer) is It is 0.01% by mass or more and 7% by mass or less with respect to 100% by mass of the total amount of the structural units constituting A). If the content of component (a3) is less than 0.01% by mass, the number of cross-linking reaction points becomes too small, resulting in poor durability. On the other hand, when the content of the component (a3) exceeds 7% by mass, the ratio of the polar monomers to be blended becomes relatively large, and the polarity of the formed pressure-sensitive adhesive layer becomes high, resulting in deterioration in durability. The content of component (a3) is preferably 0.2% by mass or more and 5% by mass or less, more preferably 0.6% by mass or more and 5% by mass or less.

[(a4) Structural Unit Derived from (Meth)acrylate Monomer Having Aromatic Ring]
The copolymer (A) according to the present invention preferably further contains (a4) a structural unit derived from a (meth)acrylate monomer having an aromatic ring (hereinafter also simply referred to as "component (a4)"). Such a component (a4) can mainly contribute to suppression of light leakage in the pressure-sensitive adhesive composition for optical films.

In the present invention, the structure of the (meth)acrylate monomer having an aromatic ring is not particularly limited, and has any structure as long as it contains an aromatic ring (aromatic ring) and a (meth)acryloyl group in its structure. can be anything. Here, the aromatic ring is not particularly limited, and includes benzene ring, naphthalene ring, biphenyl ring and the like.

Specific examples of (meth)acrylate monomers having an aromatic ring include benzyl (meth)acrylate, phenyl (meth)acrylate, o-phenylphenol (meth)acrylate, phenoxy (meth)acrylate, pt-butylphenyl (meth) Acrylates, phenoxyethyl (meth)acrylate, phenoxypropyl (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 -Those having a benzene ring such as 3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, cresyl (meth)acrylate, polystyryl (meth)acrylate; hydroxyethylated β-naphthol acrylate , 2-naphthoethyl (meth) acrylate, 2-naphthoxyethyl acrylate, 2-(4-methoxy-1-naphthoxy) ethyl (meth) acrylate having a naphthalene ring; biphenyl (meth) acrylate having a biphenyl ring include those that have Among them, benzyl (meth)acrylate and phenoxyethyl (meth)acrylate are preferable from the viewpoint of suppressing light leakage and easily ensuring durability. These components (a4) can be used alone or in combination of two or more.

The content of the component (a4) in the copolymer (A) according to the present invention (the amount of the (meth)acrylate monomer having an aromatic ring as a raw material monomer) is not particularly limited, but light leakage can be sufficiently suppressed. From the viewpoint of ensuring sufficient durability together with the (meth)acrylate copolymer, it is preferably 0% by mass or more and 30% by mass or less with respect to 100% by mass of the total amount of the structural units constituting the (meth)acrylate copolymer (A). , more preferably 10% by mass or more and 20% by mass or less.

[(a5): constituent units derived from monomers other than components (a1) to (a4)]
The copolymer (A) according to the present invention includes, as an optional component, a constituent unit derived from a monomer other than the components (a1) to (a4), which is copolymerizable with the components (a1) to (a4) described above (hereinafter referred to as Also simply referred to as “component (a5)”).

As the raw material monomer for component (a5), known monomers can be used as long as they do not impair the effects of the present invention.

Examples of raw material monomers for component (a5) include acrylic monomers having an epoxy group such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (Meth)acrylic monomers having an amino group such as Nt-butylaminoethyl (meth)acrylate, (meth)acryloyloxyethyltrimethylammonium chloride; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N, N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N,N-methylenebis (meth)acrylamide, dimethylaminopropyl (meth)acrylamide , (Meth) acrylic monomers having an amide group such as diacetone (meth) acrylamide; 2-methacryloyloxyethyl diphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacryloyloxyethyl phosphate ( (meth)acrylic monomers having a phosphoric acid group such as acrylate; (meth)acrylic monomer having a urethane group such as urethane (meth)acrylate; 2-acetoacetoxyethyl (meth)acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethyl ) vinylmonimers having a silane group such as silane, vinyltriacetylsilane, methacryloyloxypropyltrimethoxysilane; styrene, chlorostyrene, α-methylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, vinylpyridine, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (meth)acryloyl morpholine, 2-(meth)acryloyloxyethyl phthalate, tetrahydrofurfuryl (meth)acrylate, Dicyclopentenyloxyethyl (meth)acrylate, (meth) acryloylmorpholine and the like.

A (meth)acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is also preferably used as a raw material monomer for component (a5).

Examples of (meth)acrylate monomers with alkoxyalkyl groups or alkylene oxide groups include, for example, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxy ethyl (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-ethylhexyloxy-didiethylene glycol (meth) acrylate, methoxy-polyethylene glycol (meth) acrylate (n = 4-10 ), methoxydipropylene glycol (meth)acrylate, 2-ethylhexyl-diglycol acrylate, and the like.

The above-mentioned monomers can be used alone or in combination of two or more. Further, in the production of the (meth)acrylate copolymer (A) according to the present invention, the component ( It is preferable that the raw material monomers of a5) do not contain olefinic monomers such as ethylene and propylene.

In the copolymer (A) according to the present invention, among the components containing the (a1) to (a4) (that is, the components (a1) to (a5)), the homopolymer has a glass transition temperature of 50 ° C. It is preferable to (selectively) contain the structural unit derived from the above (meth)acrylate monomer (hereinafter also simply referred to as "component (a')"). Such a component (a') can ensure the hardness of the pressure-sensitive adhesive layer at room temperature, which requires dent resistance, and softens and sticks at 80 ° C. or higher, which is the heating durability test temperature at which warping occurs. In addition to being able to suppress warpage by imparting stress relaxation properties to the agent layer, it has excellent polymerizability with the above-mentioned (meth)acrylate monomer, improving durability and adhesive strength (especially reworkability). It is excellent in that it can suppress the occurrence of warpage and dents.

((Meth)acrylic (co)polymer (I))
In the adhesive composition for an optical film according to the present invention, apart from the copolymer (A), the weight average molecular weight (Mw) is smaller than that of the copolymer (A), and the glass transition temperature of the homopolymer is Further containing a (meth)acrylic (co)polymer (I) containing a structural unit derived from a (meth)acrylic monomer having a temperature of 50° C. or higher (hereinafter also simply referred to as “(co)polymer (I)”) is preferred. Such a (co)polymer (I) has structural units similar to those of the copolymer (A), but, like the high-softening-point resin (H) described below, is an acrylic resin having a low-molecular-weight component. exists separately. Therefore, since the (co)polymer (I) can move freely in the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition for an optical film containing the (co)polymer (I), It is excellent in that it becomes easier to impart stress relaxation properties to the agent layer. In addition, unlike the high softening point resin (H), the (co)polymer (I) is the same acrylic component as the copolymer (A), so the compatibility is good and the pressure-sensitive adhesive layer is highly softened. Compared with the case where the point resin (H) is contained (whitening may occur although it is small), it is excellent in that whitening is reduced (preferably no whitening). Therefore, by adding the (co)polymer (I) to impart the above-described properties, it is possible to ensure the hardness of the pressure-sensitive adhesive layer at room temperature, which requires resistance to dents, and to prevent warping. At a temperature of 80° C. or higher, which is the test temperature for heat durability, the pressure-sensitive adhesive layer is softened, giving stress relaxation to the pressure-sensitive adhesive layer, which is excellent in that warping can be suppressed.

(Weight average molecular weight of (co)polymer (I))
The weight average molecular weight (Mw) of the (co)polymer (I) 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. , 800 or more and 80,000 or less, and more preferably 1,000 or more and 50,000 or less. The (co)polymer (I), which has a molecular weight within the above range, contains structural units similar to those 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 composition for an optical film containing the (co)polymer (I), the (co)polymer (I) can move freely. , is excellent in that stress relaxation properties can be easily imparted to the pressure-sensitive adhesive layer. In addition, since the (co)polymer (I) is the same acrylic component as the copolymer (A), it has good compatibility and makes it difficult for the pressure-sensitive adhesive layer to become cloudy (preferably cloudy). is preferred because

In the adhesive composition for an optical film according to the present invention, the copolymer (A) may contain the component (a′), or the (co)polymer ( I) may be contained.

In the adhesive composition of the present invention, in order to efficiently exhibit the effects of the component (a′) and the (co)polymer (I), which are components having a homopolymer glass transition temperature of 50° C. or higher, A component having a homopolymer glass transition temperature of 50 ° C. or higher may be a constituent component of the (meth)acrylate copolymer (A), and the (meth)acrylate copolymer (A) may be separately added to the ( It may be present as a co)polymer (I). That is, the component (a') may be copolymerized with another (meth)acrylate copolymer (A) component, or the copolymer (A) and the component (a') may be copolymerized by multistage polymerization. may be polymerized, or the (co)polymer (I) may be blended separately from the copolymer (A).

In the present invention, the structure of the (meth)acrylic monomer used in the component (a′) or the (co)polymer (I) and having a homopolymer glass transition temperature of 50° C. or higher is There are no particular restrictions as long as the temperature is 50°C or higher.

Specific examples of (meth)acrylic monomers constituting the (co)polymer (I) 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 morpholine, 2-methacryloyloxyethyl phthalate, 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 esters such as octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate , furthermore, for example, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates, etc. ) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) ) acrylate, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) methacrylate, 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, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., 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, etc.), alkylaminoalkyl (meth)acrylates (eg, dimethylaminoethyl (meth)acrylate, etc.), and the like. These (meth)acrylic monomers may be used alone or in combination of two or more.

An acrylic oligomer can also be used as the (co)polymer (I). Specific examples of acrylic oligomers include "ARUFON (registered trademark)" manufactured by Toagosei Co., Ltd., "Actflow (registered trademark)" manufactured by Soken Chemical Co., Ltd., and "JONCRYL (registered trademark)" manufactured by BASF Japan Ltd. )” and other commercially available products.

Specific examples of the (meth)acrylic monomer having a homopolymer glass transition temperature of 50° C. or higher, which are used in the above component (a′) or (co)polymer (I), are shown below, but are not limited to these. not something. The values in parentheses indicate the glass transition temperature of the homopolymer.

Specific examples include isobornyl acrylate (94°C), dicyclopentenyl acrylate (120°C), dicyclopentanyl acrylate (120°C), acrylonitrile (97°C), acrylamide (165°C), and N-methylolacrylamide. (150°C), dimethylacrylamide (119°C), N-isopropylacrylamide (134°C), diethylacrylamide (81°C), dimethylaminopropylacrylamide (134°C), diacetone acrylamide (77°C), acryloyl morpholine (145°C) ° C.), 2-methacryloyloxyethyl phthalate (55° C.), methyl methacrylate (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. These can be used alone or in combination of two or more.

The content of the component (a′) in the copolymer (A) according to the present invention (the amount of the (meth)acrylic monomer in which the homopolymer as a raw material monomer has a glass transition temperature of 50° C. or higher) is determined according to the present invention. From the viewpoint of more efficiently exhibiting the effect of, it is preferably 0% by mass or more and 20% by mass or less, more preferably 0.1% by mass, based on 100% by mass of the total amount of the structural units constituting the copolymer (A). It is 0.5 mass % or more and 10 mass % or less, preferably 0.5 mass % or more and 15 mass % or less. When the content of component (a') is 20% by mass or less, it is preferable because it becomes easier to simultaneously suppress dents and warpage.

The content of the (co)polymer (I) according to the present invention is preferably 20% by mass with respect to 100% by mass of the total amount of the pressure-sensitive adhesive composition for optical films, from the viewpoint of more efficiently exhibiting the effects of the present invention. or less, 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 (I) is 20% by mass or less, advantages such as easy suppression of both dents and warpage can be obtained.

The glass transition temperature of the homopolymer may be 50° C. or higher. ° C. or higher and 150 °C or lower is more preferable, and 60 °C or higher and 120 °C or lower is even more preferable. The glass transition temperature is a value measured by differential scanning calorimetry of the homopolymer (homopolymer).

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

[Method for producing (meth)acrylate 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. A conventionally known method such as a polymerization method or a spray polymerization method can be used. The polymerization control method includes an adiabatic polymerization method, a temperature-controlled polymerization method, an isothermal polymerization method, and the like. Either a thermal polymerization initiator or a photopolymerization initiator may be used as the polymerization initiator. In addition to or in addition to the method of initiating polymerization with a polymerization initiator, a method of initiating polymerization by irradiation with active energy rays such as radiation, electron beams, and ultraviolet rays can also be employed. Among them, a solution polymerization method using a thermal polymerization initiator or a 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 which is a raw material of the copolymer (A), for example, a raw material monomer solution composed of the above monomers, and a polymerization reaction is carried out. More specifically, ethyl acetate, toluene, methyl ethyl ketone, acetone, or the like is used as a solvent, and a thermal polymerization initiator is preferably added in an amount of 0.01 part by mass or more and 1 part by mass or less with respect to 100 parts by mass of the total amount of raw material monomers. Then, in a nitrogen atmosphere, for example, the reaction temperature is 40° C. or higher and 90° C. or lower (or 60° C. or higher and 90° C. or lower) for 3 hours or more and 10 hours or less.

Thermal polymerization initiators include, for example, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis(2-methylbutyronitrile), azobiscyanovaleric acid, 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]hyde Late, 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-butyl peroxypivalate, t-butyl peroxybenzoate, t-butyl peroxy-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 are mentioned. These thermal polymerization initiators can be used alone or in combination of two or more.

In the bulk polymerization method using a photopolymerization initiator, for example, raw material monomers and a photopolymerization initiator are added, and active energy rays are irradiated at a reaction initiation temperature of 20° C. or higher and 35° C. or lower in a nitrogen atmosphere. When the temperature in the reaction system rises from the reaction initiation temperature by 5° C. or more and 15° C. or less, the reaction is stopped by introducing air into the reaction system, etc., to obtain the copolymer (A). .

Examples of active energy rays used in the bulk polymerization method include, for example, ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron beams. From the point of view, ultraviolet rays are preferably used. More preferably, ultraviolet light with a wavelength of 200 nm or more and 400 nm or less is used. Ultraviolet rays can be applied using a light source such as a high-pressure mercury lamp, a microwave excitation lamp, a chemical lamp, or a black light. The illuminance is preferably 3.2 mW/cm ² or more and 5.6 mW/cm ² or less.

Examples of photopolymerization initiators 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; Cyclohexylphenyl ketone, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone, and the like. These photopolymerization initiators may be used alone or in combination of two or more.

Commercially available photopolymerization initiators may be used, and examples of commercially available products include Irgacure (registered trademark) 184, 819, 907, 651, 1700, 1800, 819, 369, 261, and Darocure (registered trademark) TPO. , 1173 (above, manufactured by BASF Japan Co., 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.), etc. mentioned.

The amount of the photopolymerization initiator used is preferably 0.0005 parts by mass or more and 1 part by mass or less, more preferably 0.002 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the total amount of raw material monomers. be.

A chain transfer agent can also be used to adjust the molecular weight of the copolymer (A). 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 esters, 2-ethylhexylthioglycol, octyl thioglycolate, etc. mercaptans; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol, allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane, trichlorethylene; acetone, methyl ethyl ketone, Carbonyls such as cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butyraldehyde, furfural and benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic anhydride, α-methylstyrene and the like. These chain transfer agents can be used alone or in combination of two or more.

The production method for synthesizing the (co)polymer (I) is the same as the production method for the copolymer (A) described above, except that the type and amount of the monomer used, the amount of the polymerization initiator used, etc. are changed. It is the same.

<Polyrotaxane compound (B)>
The polyrotaxane compound (B) is a compound having at least two cyclic molecules with linear molecules penetrating openings and having blocking groups at both ends of the linear molecules. In this polyrotaxane compound (B), the cyclic molecule can move freely on the linear molecule, but the blocking group prevents the cyclic molecule from escaping from the linear molecule. In other words, linear molecules and cyclic molecules maintain their shape not by chemical bonds such as covalent bonds, but by so-called mechanical structures. The pressure-sensitive adhesive composition of the present invention contains the polyrotaxane compound (B) having such a mechanical structure, and the (meth)acrylic acid ester polymer (A) and the polyrotaxane compound (B) ( When the cyclic molecules in the polyrotaxane compound (B) are crosslinked, the cyclic molecules move freely on the linear molecules in the polyrotaxane compound (B), thereby significantly improving the flexibility of the crosslinked product. Thereby, the pressure-sensitive adhesive composition to be obtained has excellent durability.

The polyrotaxane compound (B) according to the present invention has, as a cyclic molecule, a cyclic oligosaccharide having a hydroxyl group as a reactive group. By using a cyclic oligosaccharide having a hydroxyl group as the cyclic molecule of the polyrotaxane compound (B), it becomes possible to select an appropriate ring diameter, thereby enhancing the effect of the movement of the cyclic molecule on the linear molecule. Easy to express. Moreover, since the cyclic oligosaccharide has a hydroxyl group as a reactive group, the reaction with the cross-linking agent (C) is facilitated. Furthermore, various substituents can be easily introduced, and this makes it possible to adjust the compatibility between the polyrotaxane compound (B) and other components by means of the polyrotaxane compound (B). Furthermore, cyclic oligosaccharides also have the advantage of being readily available. In the present specification, "cyclic" in "cyclic molecule" or "cyclic oligosaccharide" means substantially "cyclic". That is, a cyclic molecule need not be a completely closed ring, for example a helical structure, as long as it can move on a linear molecule.

Cyclic oligosaccharides include cyclodextrins such as α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin, among which α-cyclodextrin is preferred. Two or more cyclic molecules of the polyrotaxane compound (B) may be mixed in the polyrotaxane compound (B) or in the adhesive composition.

A cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (B) has a hydroxyl group as a reactive group. This hydroxyl group may be a hydroxyl group originally possessed by the cyclic oligosaccharide (meaning the state before modification), or may be a hydroxyl group introduced as a substituent into the cyclic oligosaccharide.

The lower limit of the hydroxyl value of the cyclic molecule is preferably 10 mgKOH/g or more, more preferably 30 mgKOH/g or more, and even more preferably 50 mgKOH/g or more. When the lower limit of the hydroxyl value is at least the above, the polyrotaxane compound (B) can sufficiently react with the cross-linking agent (C) (preferably an isocyanate cross-linking agent). The upper limit of the hydroxyl value of the cyclic molecule is preferably 1000 mgKOH/g or less, more preferably 200 mgKOH/g or less, and even more preferably 100 mgKOH/g or less. If the upper limit of the hydroxyl value is equal to or less than the above value, it will have appropriate cross-linking points, and as a result, the durability of the pressure-sensitive adhesive layer can be ensured. In addition, the said hydroxyl value can be measured by the method based on JISK0070:1992.

The linear molecule of the polyrotaxane compound (B) is a molecule or substance that is enclosed in a cyclic molecule and can be integrated by a mechanical bond instead of a chemical bond such as a covalent bond, and is linear. If so, it is not particularly limited. In this specification, the "straight chain" of the "straight chain molecule" means substantially "straight chain". That is, the linear molecule may have a branched chain as long as the cyclic molecule can move on the linear molecule.

Examples of linear molecules of the polyrotaxane compound (B) include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polybutadiene diol, polyisoprene diol, polyisobutylene diol, and poly(acrylonitrile-butadiene) diol. , hydrogenated polybutadiene diol, polyethylene diol, polypropylene diol, and other hydroxyl-terminated polyolefins; polycaprolactone diol, polylactic acid, polyethylene adipate, polybutylene adipate, polyethylene terephthalate, polybutylene terephthalate, and other polyesters; terminal silanol-type polydimethylsiloxane terminal functional polysiloxanes such as; terminal amino group polyethylene glycol, terminal amino group polypropylene glycol, terminal amino group chain polymers such as terminal amino group polybutadiene; trifunctional having three or more of the above functional groups in one molecule The above polyfunctional linear polymers and the like can be mentioned. Among them, polyethylene glycol and/or terminal amino group polyethylene glycol are preferably used from the viewpoint of easy availability. Two or more of these linear molecules may be mixed in the adhesive composition.

The lower limit of the number average molecular weight of the linear molecule of the polyrotaxane compound (B) is preferably 3,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. . The upper limit of the number average molecular weight of the linear molecule of the polyrotaxane compound (B) is preferably 300,000 or less, more preferably 200,000 or less, and 100,000 or less. More preferred.

The blocking group of the polyrotaxane compound (B) is not particularly limited as long as it is a group capable of maintaining a form in which a cyclic molecule is skewered by a linear molecule. Such groups include bulky groups, ionic groups and the like.

Specifically, the blocking group of the polyrotaxane compound (B) includes dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, anthracenes, etc., or a number average molecular weight of 1,000 or more. A polymer main chain or side chain having a molecular weight of 1,000,000 or less is preferable, and two or more of these blocking groups may be mixed in the polyrotaxane compound (B) or in the pressure-sensitive adhesive composition.

The weight average molecular weight of the polyrotaxane compound (B) is preferably 50,000 or more, more preferably 100,000 or more. On the other hand, it is preferably 1,000,000 or less, more preferably 800,000 or less.

A synthetic product or a commercially available product may be used as the polyrotaxane compound (B). Synthetic methods include, for example, the method described in JP-A-2005-154675.

Examples of commercially available products include SH1310P, SH2400P, and SH3400P (manufactured by Advanced Soft Materials Co., Ltd.).

The lower limit of the content of the polyrotaxane compound (B) in the adhesive composition for optical films of the present invention is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the copolymer (A). It is more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more. When the content of the polyrotaxane compound (B) is 0.01 parts by mass or more, stress relaxation properties can be imparted to the pressure-sensitive adhesive layer due to the effect of the polyrotaxane structure. The upper limit of the content of the polyrotaxane compound (B) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. When the content of the polyrotaxane compound (B) is equal to or less than the above upper limit, good compatibility with the copolymer (A) can be maintained, and an appropriate crosslinked structure can be imparted to the pressure-sensitive adhesive layer. .

<Crosslinking agent (C)>
The adhesive composition for optical films of the present invention contains a cross-linking agent (C) as an essential component. Since the cross-linking agent (C) reacts with the (meth)acrylate copolymer (A) and the polyrotaxane compound (B) to form a cross-linked structure, in the pressure-sensitive adhesive composition for an optical film, the adhesiveness (adhesiveness ) and durability.

In the present invention, the cross-linking agent (C) may contain at least one selected from the group consisting of isocyanate-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, epoxy-based cross-linking agents, and aziridine-based cross-linking agents. preferable. These various cross-linking agents are described below.

[Isocyanate-based cross-linking agent]
In the present invention, isocyanate-based cross-linking agents preferably used include triallyl isocyanurate, dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 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), Aromatic diisocyanates such as tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI); hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane Aliphatic diisocyanates such as methyl diisocyanate (NBDI); Formula diisocyanates; carbodiimide-modified diisocyanates of the above diisocyanates; or isocyanurate-modified diisocyanates thereof. Adducts of the above isocyanate compounds and polyol compounds such as trimethylolpropane, and biuret and isocyanurate of these isocyanate compounds can also be suitably used.

These isocyanate-based cross-linking agents may be synthetic products or commercially available products.

Commercially available products include, for example, Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, and Coronate (registered trademark) 2031 (manufactured by Nippon Polyurethane Industry Co., Ltd.). ), Takenate (registered trademark) D-102, Takenate (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (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 (manufactured by Asahi Kasei Chemicals Corporation), Sumidule (registered trademark) N-75, N-3200 , and N-3300 (manufactured by Sumika Bayer Urethane Co., Ltd.). Among these, Coronate® L, Coronate® HL, Coronate® HX, Takenate® D-110N, Duranate® 24A-100, Duranate® TPA -100. Among them, Takenate (registered trademark) D-110N, Coronate (registered trademark) L, Coronate (registered trademark) HX, and Duranate (registered trademark) 24A-100 are preferred.

In addition, these isocyanate-based cross-linking agents may be used in the form of unblocked isocyanate compounds, or in the form of blocked isocyanate compounds obtained by reacting with a blocking agent that protects isocyanate groups. good. Such blocked isocyanate compounds may be synthesized or commercially available. 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-hexamethylene diisocyanate) manufactured by Asahi Kasei Chemicals Corporation. Diisocyanate), Nippon Polyurethane Industry Co., Ltd.'s Coronate (registered trademark) AP-M, 2503, 2507, 2513, 2515, Millionate (registered trademark) MS-50, Mitsui Chemicals, Inc. Takenate (registered trademark) B-830 (blocked tolylene diisocyanate), B-815N (block 4,4′-methylenebis(cyclohexylisocyanate)), B-842N (block 1,3-bis(isocyanatomethyl)cyclohexane), B-846N (block 1 , 3-bis(isocyanatomethyl)cyclohexane), B-874N (blocked isophorone diisocyanate), B-882N (blocked 1,6-hexamethylene diisocyanate), manufactured by Dainippon Ink & Chemicals Co., Ltd. Barnock (registered trademark) D-500 (blocked tolylene diisocyanate), D-550 (blocked 1,6-hexamethylene diisocyanate), Elastron (registered trademark) BN manufactured by Daiichi Kogyo Seiyaku Co., Ltd. -P17 (blocked 4,4'-diphenylmethane diisocyanate), BN-04, BN-08, BN-44, BN-45 (blocked urethane-modified polyvalent isocyanate) and the like. Among these, Duranate (registered trademark) MF-K60X is particularly preferred.

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

The isocyanate-based cross-linking agent according to the present invention preferably contains an isocyanate compound having a number average molecular weight (Mn) of 900 or more and 10,000 or less. By including such an isocyanate compound, it is possible to exhibit a moderate cross-linking effect due to the long distance between cross-linking points while suppressing the denseness of the cross-linking structure of the copolymer (A). This makes it possible to achieve both suppression of foaming and suppression of peeling as heat durability. From the viewpoint of further exhibiting such effects, the number average molecular weight (Mn) is preferably 900 or more and 7,000 or less, and more preferably 1,000 or more and 5,000 or less. The number-average molecular weight (Mn) of the isocyanate-based cross-linking agent can be determined by the same method as that for measuring the weight-average molecular weight of the copolymer (A) shown in Examples.

[Carbodiimide-based cross-linking agent]
In the present invention, the carbodiimide-based cross-linking agent is not particularly limited, but as an example, a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidation catalyst is used.

Examples of the diisocyanate to be subjected to the decarboxylation condensation reaction include 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 carbodiimidation catalyst used in the decarboxylation condensation reaction include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl- Phosphorene oxides such as 2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and 3-phospholene isomers of these are included.

As the high-molecular-weight polycarbodiimide, a synthetic product or a commercially available product may be used.

Commercially available products include, for example, the 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 of their excellent compatibility with organic solvents.

[Oxazoline-based cross-linking agent]
In the present invention, the oxazoline-based cross-linking agent is not particularly limited, but includes an oxazoline-group-containing acrylic/styrene-based polymer having a main chain composed of an acrylic skeleton or a styrene skeleton and having an oxazoline group in the side chain of the main chain. 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 in a side chain of the main chain is preferably used.

The oxazoline group includes, for example, a 2-oxazoline group, a 3-oxazoline group, a 4-oxazoline group, etc. Among them, a 2-oxazoline group is preferred.

Moreover, 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 acrylics such as Epocross (registered trademark) WS-300, Epocross (registered trademark) WS-500, and Epocross (registered trademark) WS-700 manufactured by Nippon Shokubai Co., Ltd. oxazoline group-containing acrylic/styrene polymers such as Epocross (registered trademark) K-1000 series and Epocross (registered trademark) K-2000 series manufactured by Nippon Shokubai Co., Ltd.;

[Epoxy cross-linking agent]
In the present invention, the epoxy-based cross-linking agent is not particularly limited, and any known epoxy-based cross-linking agent can be appropriately employed. Examples of commercially available products include "TETRAD (registered trademark)-C" and "TETRAD (registered trademark)-X" manufactured by Mitsubishi Gas Chemical Co., Ltd., and "ADEKA RESIN (registered trademark) EPU series" manufactured by ADEKA Corporation. liquid epoxy resins such as ADEKA RESIN (registered trademark) EPR series” and “CELLOXIDE (registered trademark)” manufactured by Daicel Corporation. These liquid epoxy resins are preferable in terms of facilitating the mixing operation when producing the pressure-sensitive adhesive composition for optical films.

[Aziridine-based cross-linking agent]
In the present invention, the aziridine-based cross-linking agent is not particularly limited, but polyfunctional aziridine compounds having multiple aziridine rings can be preferably used. As polyfunctional aziridine compounds, for example, US Pat. No. 3,225,013, US Pat. Compounds disclosed in JP-A No. 104970 and the like can be mentioned.

Examples of commercially available aziridine-based cross-linking agents include Chemitite (registered trademark) PZ-33 and Chemitite (registered trademark) DZ-22E manufactured by Nippon Shokubai Co., Ltd.

In the present invention, the cross-linking agent (C) may be used alone or in combination of two or more. When two or more types are combined, two or more of the same type of cross-linking agents (e.g., two types of isocyanate-based cross-linking agents) may be combined, or one or more types of different types of cross-linking agents (e.g., isocyanate-based cross-linking agents) may be combined. One type of agent and one type of carbodiimide-based cross-linking agent) may be combined.

The content of the cross-linking agent (C) in the adhesive composition for an optical film of the present invention is not particularly limited, but is 0.001 parts by mass or more with respect to 100 parts by mass of the (meth)acrylate copolymer (A). It is preferably 20 parts by mass or less, more preferably 0.01 parts 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, and 0.05 parts by mass or more. It is particularly preferable that it is 3 parts by mass or less. A content of 0.001 part by mass or more is preferable from the viewpoint that foaming can be suppressed during heat durability. Moreover, it is preferable from the viewpoint that the occurrence 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 can be ensured even in a harsh environment, which is preferable.

<Solvent (D)>
The adhesive composition for optical films of the present invention contains a solvent (D). By containing the solvent (D), the effect of greatly improving productivity during coating can be obtained. The solvent (D) 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; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone. These solvents can be used alone or in combination of two or more.

The content of the solvent (D) in the adhesive composition for optical films of the present invention is 80% by mass or less with respect to the total mass of the adhesive composition for optical films. If the content of the solvent exceeds 80% by mass, the productivity at the time of coating is lowered, and the balance between the effect of suppressing the occurrence of warpage and dents is lowered. The content of the solvent (D) in the adhesive composition for optical films is preferably 30% by mass or more and 80% by mass or less, preferably 50% by mass, based on the total mass of the adhesive composition for optical films. It is more preferably 78% by mass or more, and even more preferably 70% by mass or more and 77% by mass or less. Within such a range of content, in addition to the effect of greatly improving durability and productivity during coating, the effect of suppressing the occurrence of warpage and dents is particularly well balanced.

Moreover, the solid content containing the copolymer (A) in the pressure-sensitive adhesive composition for optical films of the present invention is 20% by mass or more with respect to the total mass of the pressure-sensitive adhesive composition for optical films. When the solid content is less than 20% by mass, the productivity during coating is lowered, and the balance between the effect of suppressing the occurrence of warpage and dents is lowered. The solid content in the pressure-sensitive adhesive composition for optical films is preferably 20% by mass or more and 70% by mass or less, and 22% by mass or more, relative to 100% by mass of the total amount of the pressure-sensitive adhesive composition for optical films. It is more preferably 50% by mass or less, and even more preferably 23% by mass or more and 30% by mass or less. With such a content range, the balance of the effect of suppressing the occurrence of warping and dents is particularly excellent, and the solid content at the time of coating is high, and the coating speed can be secured at a higher level than ever before. It is possible to provide a pressure-sensitive adhesive composition for an optical film that can provide a pressure-sensitive adhesive optical film of good quality with excellent handleability on the surface.

The solid content in the pressure-sensitive adhesive composition for optical films of the present invention can be easily controlled by those skilled in the art by appropriately adjusting the amount of each component constituting the pressure-sensitive adhesive composition for optical films. The solid content can be measured by removing non-solid components from the adhesive composition for optical films (solid-liquid separation). The solvent content in the pressure-sensitive adhesive composition for optical films of the present invention can also be easily controlled by those skilled in the art by appropriately adjusting the amount of each component constituting the pressure-sensitive adhesive composition for optical films. The content of the solvent can be measured by volatilizing and drying the solvent from the adhesive composition for optical films.

Furthermore, the viscosity at 23°C of the adhesive composition for an optical film of the present invention measured by a Brookfield viscometer (rotation speed 20 rpm) is 200 mPa·s or more and 5000 mPa·s or less. When the viscosity is less than 200 mPa s or more than 5000 mPa s, it becomes difficult to achieve both durability and reworkability, the productivity during coating decreases, and the effect of suppressing the generation of warpage and dents. balance is lowered. The viscosity is preferably 400 mPa·s or more and 4500 mPa·s or less, more preferably 500 mPa·s or more and 4000 mPa·s or less, and particularly preferably 500 mPa·s or more and 3500 mPa·s or less. Within such a viscosity range, both durability and reworkability are achieved, and in addition to the effect of greatly improving productivity during coating, the effect of suppressing the occurrence of warpage and dents is particularly well balanced.

The viscosity at 23° C. of the pressure-sensitive adhesive composition for an optical film of the present invention measured by a Brookfield viscometer (rotation speed 20 rpm) is determined by the molecular weight of the (meth)acrylate copolymer (A), the solid content, the thickener, etc. It can be easily controlled by those skilled in the art by appropriately adjusting the viscosity by adding an additive capable of adjusting the viscosity. In this specification, the viscosity at 23° C. of the pressure-sensitive adhesive composition for optical films measured with a Brookfield viscometer (rotation speed 20 rpm) can be measured by the method shown in Examples.

<Silane coupling agent (E)>
The pressure-sensitive adhesive composition for optical films of the present invention preferably further contains a silane coupling agent (E). The silane coupling agent (E) can mainly contribute to improvement in durability and adhesion to glass when the adherend is glass in the pressure-sensitive adhesive composition for optical films. As used herein, the term "silane coupling agent" means a silane compound that does not have a siloxane bond (Si--O--Si bond) and has two or more reactive groups in the molecule.

In the present invention, the silane coupling agent (E) is not particularly limited, but specifically includes 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane 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-glycide 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. mentioned. Furthermore, a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), an amino group, a mercapto group, a (meth)acryloyl group, and a silane cup containing a functional group reactive with these functional groups A compound having a hydrolyzable silyl group obtained by reacting a ring agent, other coupling agent, polyisocyanate or the like in an arbitrary ratio for each functional group can also be used.

The silane coupling agent (E) may be a synthetic product or a commercially available 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, and KBE-9007 (manufactured by Shin-Etsu Chemical Co., Ltd.).

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

When the pressure-sensitive adhesive composition for an optical film of the present invention contains a silane coupling agent (E), the content of the silane coupling agent (E) is not particularly limited. On the other hand, it is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 5 parts by mass, still more preferably 0.01 to 3 parts by mass, Especially preferably, it is 0.01 mass part or more and 1 mass part or less. When the content is 0.001 parts by mass or more, it is preferable from the viewpoint that the effect on durability can be exhibited even under harsh environments. On the other hand, when the content is 10 parts by mass or less, it is preferable from the viewpoint that deterioration of thermal foaming due to the low-molecular-weight compound is eliminated.

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

The silicate oligomer (F) according to the present invention has a structure represented by the following chemical formula (1).

In the above chemical formula (1), 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, preferably 2 or more and 100 or less. Such alkyl groups and phenyl groups may be substituted or unsubstituted. In addition, the alkyl group may have a straight chain structure or a branched chain structure.

In the present invention, from the viewpoint of easily achieving both durability and reworkability, among the compounds represented by the chemical formula (1), all of R ¹ and R ² and X ¹ and X ² are methyl groups. A silicate oligomer is preferred. The silicate oligomer (F) can be used alone or in combination of two or more.

In the present invention, the weight average molecular weight of the silicate oligomer (F) is not particularly limited, but is preferably 300 or more and 30,000 or less, more preferably 500 or more and 25,000 or less, still more preferably 600 or more and 5,000 or less, especially It is preferably 600 or more and 5000 or less. A weight-average molecular weight of 300 or more is preferable from the viewpoint of ensuring reworkability. On the other hand, when it is 30000 or less, it is preferable from the viewpoint of easily ensuring durability. The weight-average molecular weight of the silicate oligomer (F) can be measured by the same method as that for measuring the weight-average molecular weight of the copolymer (A) shown in Examples.

When the pressure-sensitive adhesive composition for an optical film of the present invention contains a silicate oligomer (F), the content of the silicate oligomer (F) is not particularly limited, but is preferably is 0.01 to 50 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass. When the content is 0.01 parts by mass or more, it is preferable in terms of exerting an effect on durability even in a severe environment. On the other hand, when the content is 50 parts by mass or less, reworkability and durability are easily compatible, which is preferable.

<Peroxide (G)>
The pressure-sensitive adhesive composition for optical films of the present invention may further contain a peroxide (G). As used herein, the term "peroxide" means a compound having a peroxide structure "--O--O--" in its molecular structure.

In the present invention, the peroxide (G) may act as a cross-linking agent, may act as a polymerization initiator, or may have both roles.

The peroxide (G) according to the present invention is not particularly limited, and known ones can be used. In addition, the peroxide (G) preferably has a one-minute half-life temperature of 80° C. or higher and 160° C. or lower, more preferably 80° C. or higher and 140° C. or lower, in consideration of productivity and stability. It is preferably 80° C. or higher and 125° C. or lower, more preferably 90° C. or higher and 125° C. or lower, particularly preferably. The "half-life of peroxide" is an index representing the rate of decomposition of peroxide, and means the time until the residual amount of peroxide is reduced to half. Regarding the decomposition temperature for obtaining a half-life at a certain time and the half-life time at a certain temperature, it is described in the manufacturer's catalog etc. For example, the organic peroxide catalog 9th edition (2003 May 2009).

Examples of such peroxides (G) include, for example, diisopropyl peroxydicarbonate (1-minute half-life temperature 88.3 ° C., hereinafter, the temperature in parentheses indicates the 1-minute half-life temperature), di( 2-ethylhexyl)peroxydicarbonate (90.6°C), di(4-t-butylcyclohexyl)peroxydicarbonate (92.1°C), di-sec-butylperoxydicarbonate (92.4°C) , t-butyl peroxyneodecanoate (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), dibenzoyl peroxide and benzoyl m-methylbenzoyl peroxide and m-toluoyl peroxide (131.1° C.), t-butyl peroxybutyrate (136.1° C.), and the like. Among them, diisopropyl peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, and t-butyl peroxyneodecanoate are preferably used. These may be used alone, but from the viewpoint of adjusting the reactivity, it is also preferable to use two or more in combination. As an example of a combination of two or more, a combination of di(4-t-butylcyclohexyl)peroxydicarbonate and dilauroyl peroxide is suitable.

A synthetic product or a commercially available product may be used as the peroxide (G).

Commercial products include, for example, NOF Corporation trade names: "Perloyl (registered trademark, hereinafter the same) IB" (85.1 ° C.), "Percumyl (registered trademark, hereinafter the same) ND" (94.0 ° C. ), “Perloyl NPP” (94.0 ° C.), “Perloyl IPP” (88.3 ° C.), “Perloyl SBP” (92.4 ° C.), “Perocta (registered trademark, hereinafter the same) ND” (92.4 ° C.), “Perloyl TCP” (92.1 ° C.), “Perloyl OPP” (90.6 ° C.), “Perhexyl (registered trademark, hereinafter the same) 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), "Perroyl 355" (112 .6 ° C.), “Perroyl L” (116.4 ° C.), “Perocta O” (124.3 ° C.), “Perroyl SA” (131.8 ° C.), “Perhexa (registered trademark, the same applies hereinafter) 25O” ( 118.8 ° C), “Perhexyl O” (132.6 ° C), “Nyper (registered trademark, hereinafter the same) PMB” (128.2 ° C), “Perbutyl O” (134.0 ° C), “Nyper 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), "Perbutyl A" (159.9°C), "Perhexa 22" (159.9°C) and the like.

In the present invention, the content of the peroxide (G) is preferably more than 0.05 parts by mass and not more than 10 parts by mass with respect to 100 parts by mass of the (meth)acrylate copolymer (A). Within such a range, heat durability at high temperatures can be improved, and the cross-linking density becomes appropriate, thereby improving durability and stability of the pressure-sensitive adhesive composition.

Further, from the viewpoint of further satisfying heat durability at high temperatures, the content of the peroxide (G) is 0.1 parts by mass with respect to 100 parts by mass of the (meth)acrylate copolymer (A). It is preferably more than 5.0 parts by mass and more preferably more than 0.2 parts by mass and 3.0 parts by mass or less.

<High softening point resin (H)>
The pressure-sensitive adhesive composition for an optical film of the present invention further contains a high softening point resin (H) having a softening point of 60° C. or higher and 200° C. or lower (hereinafter also simply referred to as “high softening point resin (H)”). is preferred. This is because the addition of the high softening point resin (H) makes it possible to provide a pressure-sensitive adhesive composition that is somewhat hard at room temperature and softens (becomes soft) at high temperatures. By adding the above high softening point resin (H) to impart such properties, it is possible to harden at room temperature and effectively suppress the occurrence of dents. Moreover, by softening at a high temperature, stress relaxation can be imparted in a high-temperature (for example, 85° C.) environment, which is preferable in terms of being able to effectively suppress the occurrence of warping.

The high softening point resin (H) used in the present invention is not particularly limited as long as it has a softening point of 60° C. or higher and 200° C. or lower from the viewpoint of being able to effectively exhibit the above effects. , conventionally known ones can be used. Specific examples thereof include aliphatic petroleum resins, alicyclic hydrocarbon resins, aromatic petroleum resins, fully hydrogenated aliphatic petroleum resins, fully hydrogenated alicyclic hydrocarbon resins, Petroleum resins such as fully hydrogenated aromatic petroleum resins, partially hydrogenated aliphatic petroleum resins, partially hydrogenated alicyclic hydrocarbon resins, partially hydrogenated aromatic petroleum resins, aromatic hydrocarbon resins, aliphatic Rosin resins (also known as rosins or rosin derivatives) such as saturated hydrocarbon resins, terpene resins, terpene phenolic resins, hydrogenated terpene resins, cumarone-indene resins, rosin acid, polymerized rosin acid and rosin ester resins (rosin acid esters) , epoxy resins, phenol resins, oil-soluble phenols (resins), or modified resins thereof. These high softening point resins (H) may be used alone or in combination of two or more. Among these, alicyclic hydrocarbon resins, terpene phenol resins, and terpene resins are more preferable from the viewpoint of good compatibility with the copolymer (A). In addition, the high softening point resin (H) is a rosin ester resin from the viewpoint that the compatibility with other components of the pressure-sensitive adhesive composition is very good and transparency is easily obtained when applied to an optical film. It is even more preferable to have

A synthetic product or a commercially available product may be used as the high softening point resin (H).

Examples of commercially available rosin ester-based resins include Pine Crystal (registered trademark, hereinafter the same) KR-85 (softening point 80-87 ° C., hereinafter the temperature in parentheses indicates the 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) (manufactured by Arakawa Chemical Industries, Ltd.), etc. are mentioned. These are suitably used as ultra-light colored rosins for optical applications requiring transparency.

Other examples of commercially available rosin ester 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.) (manufactured by Arakawa Chemical Industries, Ltd.), and the like.

Examples of commercially available alicyclic hydrocarbon resins include Alcon (registered trademark, hereinafter the same) 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 Industries, Ltd.).

Examples of commercially available terpene phenol resins include Tamanol (registered trademark, hereinafter the same) 803L (145-160°C), Tamanol 901 (125-135°C) (manufactured by Arakawa Chemical Industries, Ltd.), and YS Polystar. (registered trademark, hereinafter the same) U130 (125-135°C), YS polyester U115 (110-120°C), YS polyester T160 (155-165°C), YS polyester T145 (140-150°C), YS polyester T130 (125) -135°C), YS Polyster T115 (110-120°C), YS Polyster T100 (95-105°C), YS Polyster T80 (75-85°C), YS Polyster S145 (140-150°C), YS Polyster G150 (145 -155°C), YS Polyster G125 (120-130°C), YS Polyster N125 (120-130°C), YS Polyster K125 (120-130°C), YS Polyster TH130 (125-135°C) (Yasuhara Chemical Co., Ltd.) made) and the like.

Examples of commercially available terpene resins include YS Resin (registered trademark, hereinafter the same) PX1250 (120-130°C), YS Resin PX1150 (110-120°C), YS Resin PX1000 (95-105°C), YS 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 (80-90° C.) (manufactured by Yasuhara Chemical Co., Ltd.) and the like.

When the high softening point resin (H) is added to the adhesive composition for optical films of the present invention, the amount of the high softening point resin (H) added is not particularly limited, but the (meth)acrylate copolymer (A ) With respect to 100 parts by mass, it is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 25 parts by mass, and 1 to 20 parts by mass more preferably 2 parts by mass or more and 15 parts by mass or less. When the content is 0.1 part by mass or more, it is preferable from the viewpoint that a softening effect is obtained during a durability test. Moreover, it is preferable from the viewpoint that the occurrence of warping can be suppressed. On the other hand, when the content is 30 parts by mass or less, it is preferable from the viewpoint that deterioration of durability due to low molecular weight substances can be suppressed. It is also preferable from the viewpoint of ensuring durability even in harsh environments, such as being able to effectively suppress deterioration in flexibility of the pressure-sensitive adhesive composition even in a low temperature range such as −25° C. or less.

The softening point of the high softening point resin (H) is preferably 60 ° C. or higher and 200 ° C. or lower, and furthermore, heat resistance retention, adhesiveness, flexibility in a low temperature range such as -25 ° C. or lower, durability and reworkability. from the viewpoints of improvement in temperature and suppression of warping and dents, the temperature is more preferably 70° C. or higher and 150° C. or lower, still more preferably 80° C. or higher and 140° C. or lower, and particularly preferably 85° C. or higher and 130° C. or lower. In addition, in this invention, the said softening point shall employ|adopt the value measured by the method of JISK6863 (1994).

<Other additive ingredients>
The pressure-sensitive adhesive composition for an optical film of the present invention may optionally contain a cross-linking accelerator, an anti-aging agent, a filler, a coloring agent (pigment, dye, etc.), an ultraviolet absorber, an antioxidant, a chain transfer agent, and a plasticizer. Known additive components (other additive components) such as agents, softeners, surfactants, antistatic agents, etc. may be contained within a range that does not impair the effects of the present invention.

<Production (preparation) method of pressure-sensitive adhesive composition>
In the present invention, the pressure-sensitive adhesive composition for optical films is not particularly limited, and may optionally contain, for example, a copolymer (A), a polyrotaxane compound (B), a cross-linking agent (C), and a solvent (D). It can be prepared by mixing a silane coupling agent (E), a silicate oligomer (F), and other additives. The mixing order and mixing temperature of the above components are not particularly limited, and can be appropriately adjusted by those skilled in the art.

[Use]
The pressure-sensitive adhesive composition for optical films of the present invention described above is suitable for various uses. For example, it is preferably used for optical members such as optical films. In particular, in recent years, it is preferably used for thin pressure-sensitive adhesive optical films used in large-sized liquid crystal panels. Such optical films include polarizing plates, retardation plates for preventing coloration, optical compensation films such as viewing angle widening films for improving the viewing angle of liquid crystal displays, brightness enhancement films for increasing the contrast of displays, Furthermore, the thing in which these are laminated|stacked is mentioned.

In the present invention, the form of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for an optical film described above, the form of the optical member formed by forming the pressure-sensitive adhesive layer on an optical film or the like, and the optical film being a polarizing plate. A form or 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 can also be provided. Each of these 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 formed from the above-described pressure-sensitive adhesive composition 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 use, but 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. A thickness within the above range is preferable from the viewpoint of achieving a good balance between durability and adhesive properties.

Although the gel fraction of the pressure-sensitive adhesive layer of the present invention immediately after drying is not particularly limited, it is preferably 95% or less from the viewpoint of punching or slitting. In addition, from the viewpoint of eliminating concerns about dents, warping, and durability of the adhesive layer immediately after drying and requiring no aging treatment, it is preferably 40% or more, and more preferably 65% or more. The gel fraction can be adjusted by controlling the amount of cross-linking agent and the amount of peroxide.

[Method for producing pressure-sensitive adhesive layer]
According to another aspect of the present invention, the pressure-sensitive adhesive composition for optical films of the present invention is coated on a release sheet that has been subjected to release treatment, and then heat-treated to cause a cross-linking reaction. A method of making the agent layer is also provided.

When the pressure-sensitive adhesive composition is used for an optical film, the pressure-sensitive adhesive composition may be applied directly onto the optical film to form a pressure-sensitive adhesive layer. It is desirable to apply the material to form a pressure-sensitive adhesive layer, and then transfer it to various optical films for use. In addition, the film having releasability with the pressure-sensitive adhesive layer produced in this way can also be wound together in the production process to form a roll, and can be cut and processed as necessary to produce various products. When the film is attached to an optical film, a liquid crystal panel, or the like, the film having releasability can be removed before use. Furthermore, the release film can also serve to protect the adhesive layer until the adhesive layer is put to practical use. In this specification, such a film having releasability is also referred to as a release sheet (separator).

Materials constituting the release sheet include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, laminates thereof, and the like. However, a plastic film is preferably used because of its 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.

For the release sheet, silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agents, release treatment and antifouling treatment with silica powder, etc., coating type, kneading type, vapor deposition, etc. Antistatic treatments such as molds can be further applied. In particular, it is preferable to subject the surface of the release sheet to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, from the viewpoint of further enhancing the releasability from the pressure-sensitive adhesive layer.

In the present invention, the coating method for coating the adhesive composition for an optical film of the present invention onto a release sheet that has been subjected to release treatment is not particularly limited, and various known methods are used. For example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, etc. method.

In the method for producing a pressure-sensitive adhesive layer of the present invention, a step of heat-treating is performed after applying the above-described pressure-sensitive adhesive composition for an optical film onto a release sheet. The heat treatment step not only dries and removes the solvent in the coating film obtained by coating, but also fulfills the purpose of cross-linking the above-described pressure-sensitive adhesive composition for optical films. 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 still more preferably 80° C. or higher and 120° C. or lower. By setting the temperature of the heat treatment within the above range, a pressure-sensitive adhesive layer having excellent adhesive properties can be obtained.

The heat treatment time can be set as appropriate, but is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, still more preferably 10 seconds to 5 minutes, particularly It is preferably 10 seconds or more and 2 minutes or less.

Moreover, the means for the heat treatment is not particularly limited, and various known methods are used. For example, the parallel drying method blows hot air in the direction of film transport in the same direction up and down, the counter drying method blows hot air in different directions in the direction of film transport, and the float drying method blows hot air directly from the top and bottom of the film. method.

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

Moreover, the optical member of the present invention can 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 provided with the first optical film. Here, the "first optical film" and the "second optical film" may be films having the same configuration (materials, functions, etc.), or may be films having different configurations (materials, functions, etc.). It may be a film having Moreover, in the present invention, there is also provided a mode in which the first optical film (or the second optical film) is a polarizing plate.

In the present invention, the pressure-sensitive adhesive composition described above may be used by directly applying it to one or both sides of an optical film to form a pressure-sensitive adhesive layer. It is desirable to use it by forming it and transferring it to one or both sides of an optical film. Prior to the transfer, the surface of the optical film may be subjected to surface treatment such as formation of an easy-adhesion treatment layer or formation of an antistatic layer, depending on the material. Also, the surface of the pressure-sensitive adhesive layer may be subjected to an easy-adhesion treatment. From the viewpoint of firmly bonding 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 adhesion-facilitating layer between the first optical film and the optical film pressure-sensitive adhesive layer.

Further, as a more preferable embodiment, the optical member of the present invention has a first easy-adhesion treatment layer on the surface of the first optical film facing the pressure-sensitive adhesive layer for an optical film, and The surface of the pressure-sensitive adhesive layer for optical discs facing the first optical film has a second easy-adhesion treatment layer. Such a configuration in which the optical member has both the first and second easy-adhesion treatment layers is preferable from the viewpoint that the optical film and the pressure-sensitive adhesive layer can be adhered more firmly.

As the easy-adhesion treatment layer, the surface of the member in contact with the adhesive layer may be treated by corona treatment, plasma treatment, or the like, or a separate member such as a primer layer may be applied to the member in contact with the adhesive layer. may be provided on the surface of

The material constituting the primer layer preferably has good adhesion to members in contact with the primer layer and forms a film with excellent cohesive force. For example, various polymers, metal oxide sols, silica sols, etc. 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 containing amino groups in the molecule. Among them, polyurethane resins and oxazoline group-containing polymers are more preferably used.

A commercial item can be used for the oxazoline group-containing polymer. Examples include, but are not limited to, the Epocross (registered trademark) series manufactured by Nippon Shokubai Co., Ltd. (eg, Epocross (registered trademark) WS700). As for polyurethane resins, polyester resins, polymers containing amino groups in the molecule, etc., those disclosed in paragraphs "0107" to "0113" of JP-A-2011-105918 can be employed as appropriate.

The thickness of the primer layer is preferably 10 nm or more and 5000 nm or less, 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 the primer layer can be formed by applying the raw material (undercoat agent) for the primer layer using a coating method such as a coating method, a dipping method, or a spray method, and drying. .

<Optical film>
In the present invention, the optical film (first optical film or second optical film) includes optical films 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. They include, but are not limited to, compensation films, brightness enhancement films to increase display contrast, and laminates thereof.

<Polarizing plate>
In the present invention, a polarizing plate suitable as an optical film is produced by bonding a protective film and a polarizer together using an adhesive and curing by heat drying or ultraviolet rays, electron beams, or the like by a conventionally known method. obtain. The applied adhesive develops adhesiveness by drying or by curing with ultraviolet rays, electron beams, or the like, and constitutes an adhesive layer.

The polarizer is not particularly limited, and conventionally known polarizers can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene/vinyl acetate copolymer film is allowed to adsorb a dichroic material such as iodine or a dichroic dye. Polyene-based oriented films such as those uniaxially stretched by stretching, polyvinyl alcohol dehydrated products, polyvinyl chloride dehydrochlorinated products, and the like.

Among them, a polarizer produced by dyeing a polyvinyl alcohol film having an average degree of polymerization of 2000 to 2800 and a degree of saponification of 90 mol% to 100 mol% with iodine and uniaxially stretching 3 to 8 times is particularly preferable. . More specifically, such a polarizer is obtained, for example, by 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, for example, immersion in an aqueous solution containing 0.1% by mass or more and 10% by mass or less of iodine and/or potassium iodide is preferable. In addition, if necessary, it may be immersed in an aqueous solution of boric acid or potassium iodide at a temperature of 50° C. or higher and 70° C. or lower. good too. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. After dyeing and stretching, the fabric may be washed with water and dried at 35° C. or higher and 55° C. or lower for about 1 minute or longer and 10 minutes or shorter. A wide variety of such polarizers are commercially available.

Also, 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. The method of protection is not particularly limited, and a known method such as attaching a protective film can be appropriately employed.

As the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. is preferable. For example, ( 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, and the other side is provided with a transparent protective film or a (meth)acrylic, urethane, acrylic urethane, epoxy, or a protective layer. A thermosetting resin such as silicone or an ultraviolet curable resin can be used.

Although the thickness of the polarizing plate is not particularly limited, it is generally 20 μm or more and 200 μm or less. From the viewpoint of thinning, the thickness of the polarizing plate is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less. Such a thin polarizing plate is preferable from the viewpoint of exhibiting the effects of the pressure-sensitive adhesive composition of the present invention more remarkably.

The method for producing the polarizing plate is not particularly limited, and for example, after applying the adhesive, the polarizer and the protective film can be laminated together using a roll laminator or the like. After bonding, drying or a curing step using ultraviolet rays, electron beams, or the like may be performed as appropriate. Moreover, 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. Moreover, the adhesive is not particularly limited, and can 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, an acrylic, epoxy, or acrylic-epoxy adhesive can be used as the polyvinyl alcohol-based adhesive or the UV-curable adhesive. The thickness of the adhesive layer is preferably 10 nm or more and 200 nm or less for a polyvinyl alcohol-based adhesive, and 0 nm or less for an ultraviolet curable adhesive, in order to obtain a uniform in-plane thickness and sufficient adhesive strength. .2 μm or more and 10 μm or less.

In the present invention, an adhesive polarizing plate having an adhesive layer formed thereon can also be provided. The configuration and production of the pressure-sensitive adhesive polarizing plate are the same as in the case of the optical film having the pressure-sensitive adhesive layer described above, so the description is omitted here.

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

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), a micro LED display, and the like. In addition, from the viewpoint of exhibiting the effects of the pressure-sensitive adhesive composition of the present invention more remarkably, a thin image display device is particularly preferably applied.

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

In addition, in the following operations, unless otherwise specified, the operations and physical properties are measured under the conditions of 23° C. and 55% RH.

(Measurement of weight average molecular weight (Mw) of copolymer (A))
The weight average molecular weight of each (meth)acrylate copolymer (A) prepared in the following production examples was measured by gel permeation chromatography (GPC) (see below for measurement conditions).
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
・ Column: G7000HXL + GMHXL + GMHXL manufactured by Tosoh Corporation
・Column size: 7.8 mmφ×30 cm each, 90 cm in total
・Column temperature: 40°C
・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))
Further, the weight average molecular weight of the silicate oligomer (F) used in the following examples was measured by gel permeation chromatography (GPC) (see below for measurement conditions):
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
・Column: TSKgel SuperHZM-H/HZ4000/HZ2000
- Column size: 6.0 mmI. D. ×150mm
・Column temperature: 40°C
・Flow rate: 0.6 ml/min
・Injection volume: 20 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
- Standard sample: Polystyrene.

[Production Example 1: Preparation of solution of (meth)acrylate copolymer (A1)]
99 parts by mass of n-butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) and 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) were added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler. ) 1 part by mass and 0.1 part by mass of 2,2′-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator were charged together with 100 parts by mass of ethyl acetate and gently stirred. Nitrogen gas was introduced while After purging with nitrogen gas, the temperature of the liquid in the flask was raised until ethyl acetate refluxed, and the polymerization reaction was performed for 5 hours to obtain a solution of (meth)acrylate copolymer (A1) having a weight average molecular weight (Mw) of 900,000. was prepared.

[Production Examples 2 to 11: Preparation of solutions of (meth)acrylate copolymers (A2) to (A11)]
Same as Production Example 1 except that the type and composition ratio of each monomer forming the (meth)acrylate copolymer were changed as shown in Table 1 below, and the amount of the polymerization initiator and the reaction time were changed as appropriate. Operations were performed to prepare solutions of (meth)acrylate copolymers (A2) to (A11). Table 1 also shows the weight average molecular weights (Mw) of the (meth)acrylate copolymers (A1) to (A8) and (A10) to (A11). A blank in Table 1 indicates that the monomer was not used. The weight-average molecular weight of the methacrylate copolymer (A9) could not be measured because the solution gelled.

<Example 1>
[Preparation of adhesive composition for optical film]
The polyrotaxane compound (B) is added to the solid content of 100% by mass of the (meth)acrylate copolymer (A1) solution obtained in Production Example 1 (that is, 100 parts by mass of the (meth)acrylate copolymer (A1)). As SH1310P (manufactured by Advanced Soft Materials Co., Ltd., number average molecular weight of linear molecule (polyethylene glycol): 11,000, hydroxyl value of cyclic molecule: 85 mgKOH / g, weight average molecular weight of compound: 180,000) 2 Parts by mass, Takenate (registered trademark) D-110N as a cross-linking agent (C) (75% by weight ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate, number of isocyanate groups in one molecule: 3, manufactured by Mitsui Chemicals, Inc. ) 0.1 parts by mass (converted to active ingredient), and 0.1 parts by mass of KBM-403 (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (E) are stirred and mixed. Thus, an optical film pressure-sensitive adhesive composition (solid content: 25% by mass) was prepared.

[Formation of adhesive layer]
The pressure-sensitive adhesive composition for an optical film obtained above was applied to one side of a 38 μm thick polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, MRF38, no oligomer prevention layer) that had been subjected to silicone treatment. The pressure-sensitive adhesive layer of Example 1 was formed by applying a pressure-sensitive adhesive layer having a thickness of 20 μm and heat-treating at 110° C. for 2 minutes. The heat treatment was performed by a float drying method in which hot air was directly blown from above and below the film.

[Production of optical member]
(Preparation of double-sided protective polarizing plate)
A double-sided protective polarizing plate was produced as an optical film by the following steps.

A polyvinyl alcohol film having a thickness of 60 μm was stretched up to 3 times while being dyed in an iodine solution having a concentration of 0.3% by mass at 30° C. for 1 minute between rolls having different speed ratios. After that, the film stretched to 3 times was immersed in an aqueous solution containing 4% by mass of boric acid and 10% by mass of potassium iodide at 60° C. for 0.5 minutes while being stretched until the total stretching ratio became 6 times. did. Then, the film stretched up to 6 times was washed by immersing it in an aqueous solution containing potassium iodide at 30° C. and 1.5% by mass for 10 seconds, and then dried at 50° C. for 4 minutes to obtain a polarizer. rice field. A 40 μm-thick triacetyl cellulose (TAC) film (protective film) is provided on one side of the polarizer, and an 80 μm-thick PET film (Cosmo Shine (registered trademark) manufactured by Toyobo Co., Ltd.) on the other side. Type (SRF) PET film; protective film) was laminated with a polyvinyl alcohol-based adhesive to prepare a double-sided protective thin polarizing plate (simply referred to as a double-sided protective polarizing plate) having a total thickness of 143 μm.

(Preparation of double-sided protective polarizing plate with adhesive layer)
The TAC film side of the double-sided protective polarizing plate obtained above was subjected to corona treatment at a discharge amount of 80 [W·min/m ² ] to form an easy-adhesion treatment layer. Next, a PET film (with silicone treatment) having an adhesive layer formed thereon was transferred so as to be in contact with the formed easy-adhesion treatment layer, and the optical member of Example 1, that is, the adhesive layer-attached double-sided protective polarizing plate was obtained. made.

<Examples 2 to 26 and Comparative Examples 1 to 4>
As shown in Table 2 below, a (meth)acrylate copolymer (A), a polyrotaxane compound (B), a cross-linking agent (C), and, if necessary, silane coupling, which constitute the optical film pressure-sensitive adhesive composition Examples 2 to 26 and Comparative Examples 1 to 4 were prepared in the same manner as in Example 1, except that the types and amounts added (blending amounts) of the agent (E) and silicate oligomer (F) were changed. A double-sided protective polarizing plate with an adhesive layer was produced.

In Table 2 above,
1. The amount (parts by mass) of components (B), (C), (E), (F), (G), (H), and (I) is 100 masses of (meth)acrylate copolymer (A). 2. Represents the compounding amount in the case of parts. "-" in the table indicates that such component is not blended.3. "SH2400P": A product manufactured by Advanced Soft Materials Co., Ltd. (Number average molecular weight of linear molecule (polyethylene glycol): 20,000, hydroxyl value of cyclic molecule: 76 mgKOH/g, weight average molecular weight of compound: 400,000) 4. "SH3400P": A product manufactured by Advanced Soft Materials Co., Ltd. (Number average molecular weight of linear molecule (polyethylene glycol): 35,000, hydroxyl value of cyclic molecule: 72 mgKOH/g, weight average molecular weight of compound: 70 4. It is 10,000). "Methyl Silicate 53A": A product manufactured by Colcoat Co., Ltd. (trade name: Methyl Silicate 53A)6. "V-05": A carbodiimide-based cross-linking agent, a product (Carbodilite (registered trademark) V-05) manufactured by Nisshinbo Chemical Co., Ltd.7. "WS-500": An oxazoline-based cross-linking agent, a product (Epocross (registered trademark) WS-500) manufactured by Nippon Shokubai Co., Ltd.8. "TETRAD-X": An epoxy-based cross-linking agent, a product (TETRAD (registered trademark)-X, N, N, N', N'-tetraglycidyl-m-xylenediamine) manufactured by Mitsubishi Gas Chemical Company, Inc. 9. “PZ-33”: an aziridine-based cross-linking agent, a product manufactured by Nippon Shokubai Co., Ltd. (Kemitite (registered trademark) PZ-33, 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate) 10. is “Nyper BMT-K40”: A product manufactured by NOF Corporation (benzoyl peroxide, active ingredient content: 40% by mass, 1-minute half-life temperature: 131.1° C.). The amount added in Table 2 above is the amount added in terms of the amount of active ingredient.11. “Pine Crystal KE-100”: A product manufactured by Arakawa Chemical Industries, Ltd. (softening point 95-105° C. (ring and ball method), ultra-light colored rosin derivative).12. “Alphon (registered trademark) UH-2170”: A product manufactured by Toagosei Co., Ltd. (solvent-free styrene acrylic polymer, weight average molecular weight (Mw) 14,000, glass transition temperature (Tg) 60° C.).

[evaluation]
The optical film pressure-sensitive adhesive compositions prepared in Examples 1 to 26 and Comparative Examples 1 to 4, and the double-sided protective polarizing plate (sample) having a pressure-sensitive adhesive layer, which is an optical member, were evaluated as follows. rice field.

<Coating liquid solid content (solid content)>
The pressure-sensitive adhesive compositions for optical films prepared in Examples 1 to 26 and Comparative Examples 1 to 4 above were dried by heating at 150° C. for 30 minutes, and the volatile residue at that time was referred to as "coating liquid solid content (% by mass) "

<Viscosity>
For the adhesive compositions for optical films prepared in Examples 1 to 26 and Comparative Examples 1 to 4 above, the rotor was rotated at a rotation speed of 20 rpm with a Brookfield viscometer (Brookfield viscometer), and 1 minute from the start. The subsequent numerical value was read and used as the viscosity value.

<Warp>
The optical members (double-sided protective polarizing plates with pressure-sensitive adhesive layers) produced in Examples 1 to 26 and Comparative Examples 1 to 4 were cut into a size of 100 mm long and 50 mm wide to obtain samples. This sample was adhered to non-alkali glass (Eagle XG manufactured by Corning Inc.) having a size of 75 mm long×150 mm wide×0.5 mm thick using a laminator. Then, autoclave treatment was performed at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to non-acrylic glass. After further heat treatment at 85 ° C. for 100 hours to the sample subjected to such treatment, it was left for 1 hour under the conditions of 25 ° C. and 55% relative humidity RH, after which the amount of warpage became convex. The sample was placed on a horizontal surface with the surface facing downward, and the distance (mm) of the longest point from the horizontal surface among the four corner points was measured. Evaluation criteria were as follows:
-Evaluation criteria-
A: Amount of warp 0 mm or more and less than 0.5 mm A: Amount of warp 0.5 mm or more and less than 1.0 mm B: Amount of warp 1.0 mm or more and less than 1.5 mm x: Amount of warp 1.5 mm or more.

<Hits>
Immediately after coating (immediately after transfer of PET film with adhesive layer; within 10 minutes after transfer) prepared in Examples 1 to 26 and Comparative Examples 1 to 4 above (double-sided protective with adhesive layer) A polarizing plate) was cut into a size of 100 mm long by 100 mm wide to prepare a total of 300 sample pieces (samples). These sample pieces are stacked with the PET film (protective film) surface of the polarizing plate (protective film surface on the side where the adhesive layer is not formed) facing up, and a weight of 1 kg is applied from above, 23 ° C., relative humidity It was left under conditions of 50% RH for 1 day, and the depth of dents was evaluated with a laser microscope (VK-X120) manufactured by Keyence Corporation. Evaluation criteria were as follows:
-Evaluation criteria-
A: Depth of dent 0 μm or more and less than 1 μm O: Depth of dent 1 μm or more and less than 3 μm Δ: Depth of dent 3 μm or more and less than 5 μm ×: Depth of dent 5 μm or more.

<Durability>
The optical members (double-sided protective polarizing plate with adhesive layer) produced in Examples 1 to 26 and Comparative Examples 1 to 4 above were cut into 37-inch size samples, and alkali-free glass (Corning Co., Ltd.) with a thickness of 0.7 mm was used. manufactured by Eagle XG) using a laminator. Then, autoclave treatment was performed at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to non-acrylic glass. The thus-treated samples were subjected to the following durability tests (1) to (3), and after each test, the appearance between the polarizing plate and the glass was visually evaluated according to the following criteria:
(1) Treated at 85°C for 500 hours (heating test)
(2) Treated for 500 hours in an atmosphere of 60° C./relative humidity of 95% RH (humidification test)
(3) One cycle (1 hour) was left for 30 minutes in an environment of 85 ° C. and then left for 30 minutes in an environment of -40 ° C., and a total of 300 cycles (300 hours) were treated (heat shock (HS) test .

Visual evaluation ◎: No change in appearance such as foaming, peeling, or lifting ○: Slight peeling or foaming at the edge, but no practical problem △: Peeling or foaming at the edge , Practically no problem unless it is used for a special purpose. x: Significant peeling at the edge, presenting a practical problem.

<Oligomer contamination>
While coating the pressure-sensitive adhesive compositions of Examples 1 to 26 and Comparative Examples 1 to 4 above on a polyethylene terephthalate (PET) film (thickness 38 μm, manufactured by Mitsubishi Chemical Corporation, MRF38) without an oligomer prevention layer. , under the heat treatment temperature shown in Table 2 for 2 hours on the coating line. When the heat treatment was carried out while the film was conveyed, it was visually observed whether or not the PET oligomer was precipitated on the guide roll of the coating line, and evaluated according to the following criteria:
Evaluation Criteria ◯: No precipitation of PET oligomer on the guide roll Δ: Some amount of PET oligomer precipitation on the guide roll ×: A large amount of PET oligomer precipitation on the guide roll.

<Light leakage>
Each of the optical members prepared in Examples 1 to 26 and Comparative Examples 1 to 4 was cut into a size of 420 mm long×320 mm wide so that the upper and lower polarizing plates were perpendicular to each other, and used as samples. This sample was laminated on both sides of a 0.7 mm thick non-alkali glass plate (Eagle XG (registered trademark) manufactured by Corning Incorporated) with a laminator so as to form crossed Nicols. Then, autoclave treatment was performed at 50° C. and 5 atm for 15 minutes to obtain a secondary sample (initial stage). A secondary sample was then treated at 105° C. for 48 hours (after heating). After heating, the secondary sample was placed on a 10,000 candela backlight, and the light leakage was visually evaluated according to the following criteria:
Evaluation Criteria ◎: No corner unevenness, no practical problem ○: Corner unevenness occurs slightly, but it does not appear in the display area, so there is no practical problem △: Corner unevenness occurs and is displayed Although it appears slightly in the area, it is not a problem in practical use. ×: Corner unevenness occurs and appears strongly in the display area, which is a problem in practical use.

<Reworkability>
The optical members prepared in Examples 1 to 26 and Comparative Examples 1 to 4 were cut into a size of 25 mm in width and 100 mm in length as sample 1, and cut into a size of 420 mm in length and 320 mm in width as sample 2 (three pieces were produced). did. Each of Sample 1 and Sample 2 was attached to an alkali-free glass plate (manufactured by Corning, Eagle XG) with a thickness of 0.7 mm using a laminator, and then autoclaved at 50 ° C. and 5 atm for 15 minutes to complete. They were brought into close contact (initial stage). After that, heat treatment was performed for 48 hours under dry conditions at 50°C (after heating).

The adhesive strength of Sample 1 was measured. The adhesive strength was measured using a tensile tester (manufactured by Orientec Co., Ltd., Tensilon Universal Material Testing Machine, STA-1150) under the conditions of 23 ° C. and relative humidity of 50% RH, at a peel angle of 180 ° and a peel speed of 300 mm / min. It was obtained by measuring the adhesive strength (N/25 mm) when peeling off the sample 1 in accordance with the method for testing adhesive tapes and adhesive sheets of JIS Z0237 (2009).

In addition, with respect to the sample 2 (three sheets), the sample was manually peeled off from the alkali-free glass plate, and the reworkability was evaluated according to the following criteria (actual reworkability):
Evaluation criteria ◎: All 3 sheets can be peeled off satisfactorily without adhesive residue or film breakage Can be peeled off by repeated peeling ×: Adhesive residue occurred on all three sheets, or the film was broken and could not be peeled off no matter how many times it was peeled off.

Each evaluation result is shown in Table 3 below.

As is clear from Table 3 above, the adhesive layer-attached double-sided protective polarizing plates using the adhesive compositions for optical films of Examples 1 to 26 all performed under harsh environments (high temperature, high humidity). , heat shock) and reworkability can be achieved at the same time, and the occurrence of both warpage and dents can be suppressed. Specifically, the pressure-sensitive adhesive layer-attached double-sided protective polarizing plates (Examples 1 to 26), which are optical members having a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition for an optical film of the present invention, were used in a high-temperature and high-humidity environment. There was almost no peeling, lifting, or foaming due to the adhesive in the durability test. In addition, the double-sided protective polarizing plate with an adhesive layer, which is an optical member, can be reduced in adhesive force immediately after it is attached to a thinner image display device, such as a liquid crystal cell of a large liquid crystal display device, and various A double-sided protective polarizing plate with an adhesive layer, which is an optical member, does not increase in adhesive strength to liquid crystal cells, etc. It was suggested that the can be easily peeled off. As a result, it was confirmed that the reworkability was excellent and that the liquid crystal cell and the like could be reused without being damaged or contaminated. Conventionally, in liquid crystal cells and the like used in large-sized image display devices, it has been difficult to suppress both warpage of the liquid crystal cells and dents in the pressure-sensitive adhesive layer, but according to Examples 1 to 26, , it was also confirmed that these characteristics can be satisfied at the same time. On the other hand, the pressure-sensitive adhesive layer-attached double-sided protective polarizing plates of Comparative Examples 1 to 4 are difficult to achieve both durability and reworkability in harsh environments (high temperature, high humidity, heat shock). It was found that neither one could be suppressed.

Claims (25)

(a1) A structural unit derived from an alkyl (meth)acrylate monomer, and a structural unit derived from a (meth)acrylate monomer having a (a2) hydroxyl group of 0.01 to 10% by mass with respect to 100% by mass of the total amount of structural units, Or 0.01 to 10% by weight of the total amount of structural units and 0.01 to 100% by weight of structural units derived from (a2) hydroxyl group-derived (meth) acrylate monomers with respect to the total amount of 100% by weight 7% by mass of (a3) a monomer-derived structural unit having a carboxyl group,
(Meth)acrylate copolymer (A),
A polyrotaxane compound (B) having, as a cyclic molecule, a cyclic oligosaccharide having a hydroxyl group as a reactive group,
a cross-linking agent (C), and a solvent (D),
An optical film pressure-sensitive adhesive composition comprising
The (meth)acrylate copolymer (A) has a weight average molecular weight of 300,000 or more and 1,200,000 or less by gel permeation chromatography (GPC),
The solid content containing the (meth)acrylate copolymer (A) in the pressure-sensitive adhesive composition for optical films is 20% by mass or more with respect to the total weight of the pressure-sensitive adhesive composition for optical films,
The content of the solvent (D) in the pressure-sensitive adhesive composition for optical films is 80% by mass or less with respect to the total weight of the pressure-sensitive adhesive composition for optical films,
The pressure-sensitive adhesive composition for an optical film has a viscosity of 200 mPa s or more and 5000 mPa s or less at 23° C. measured by a Brookfield viscometer (rotation speed 20 rpm),
The (a1) alkyl (meth)acrylate monomers are methyl (meth)acrylate and n-butyl (meth)acrylate,
The (meth)acrylate copolymer (A) contains a structural unit derived from 4-hydroxybutyl (meth)acrylate as a structural unit derived from (a2) a (meth)acrylate monomer having a hydroxyl group,
A pressure-sensitive adhesive composition for an optical film, wherein the (meth)acrylate copolymer (A) further contains (a4) a structural unit derived from an aromatic-containing (meth)acrylate monomer. The optical film according to claim 1, wherein the content of the polyrotaxane compound (B) is 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the (meth)acrylate copolymer (A). adhesive composition for 3. The pressure-sensitive adhesive composition for an optical film according to claim 1, wherein the (a4) aromatic-containing (meth)acrylate monomer is benzyl (meth)acrylate. Any one of claims 1 to 3, further comprising 0.01 parts by mass or more and 1 part by mass or less of a silane coupling agent (E) with respect to 100 parts by mass of the (meth)acrylate copolymer (A). The pressure-sensitive adhesive composition for an optical film as described in 1. The optical film pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a silicate oligomer (F) having a structure represented by the following chemical formula (1):

In the above chemical formula (1),
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 composition for an optical film according to claim 5, wherein the silicate oligomer (F) comprises a methyl silicate oligomer. The pressure-sensitive adhesive composition for an optical film according to claim 5 or 6, wherein the silicate oligomer (F) has a weight average molecular weight of 300 or more and 30000 or less. The cross-linking agent (C) comprises at least one selected from the group consisting of an isocyanate-based cross-linking agent, a carbodiimide-based cross-linking agent, an oxazoline-based cross-linking agent, an epoxy-based cross-linking agent, and an aziridine-based cross-linking agent. 8. The pressure-sensitive adhesive composition for an optical film according to any one of 7. The pressure-sensitive adhesive composition for an optical film according to claim 8, wherein the isocyanate-based cross-linking agent contains an isocyanate compound having a number average molecular weight of 900 or more and 10,000 or less. The pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 9, further comprising a peroxide (G). The pressure-sensitive adhesive composition for an optical film according to claim 10, wherein the peroxide (G) has a 1-minute half-life temperature of 80°C or higher and 125°C or lower. The pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 11, further comprising a high softening point resin (H) having a softening point of 60°C or higher and 200°C or lower. The pressure-sensitive adhesive composition for an optical film according to claim 12, wherein the high softening point resin (H) is a rosin ester resin. The copolymer (A) according to any one of claims 1 to 13, wherein the homopolymer contains a structural unit (a') derived from a (meth)acrylic monomer having a glass transition temperature of 50°C or higher. A pressure-sensitive adhesive composition for an optical film. (Meth)acrylic containing a structural unit derived from a (meth)acrylic monomer having a weight average molecular weight (Mw) smaller than that of the (meth)acrylate copolymer (A) and a glass transition temperature of the homopolymer of 50° C. or higher The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 14, further comprising a system (co)polymer (I). The pressure-sensitive adhesive composition for an optical film according to claim 15, wherein the (meth)acrylic (co)polymer (I) has a weight average molecular weight (Mw) of 500 or more and 100,000 or less. An optical film pressure-sensitive adhesive layer formed from the optical film pressure-sensitive adhesive composition according to any one of claims 1 to 16. The pressure-sensitive adhesive layer for an optical film according to claim 17;
a first optical film provided on one surface of the pressure-sensitive adhesive layer;
An optical member. 19. The optical member according to claim 18, further comprising glass or a second optical film on the surface of the pressure-sensitive adhesive layer opposite to the surface provided with the first optical film. 20. The optical member according to claim 18, further comprising at least one easy-adhesion treatment layer between said first optical film and said pressure-sensitive adhesive layer for optical film. The first optical film has a first easy-adhesion treatment layer on the surface facing the optical film pressure-sensitive adhesive layer,
21. The optical member according to claim 20, wherein the surface of the optical film pressure-sensitive adhesive layer facing the first optical film has a second easy-adhesion treatment layer. The optical member according to any one of claims 18 to 21, wherein the first optical film is a polarizing plate. An image display device using at least one optical member according to any one of claims 18 to 22. 17. The pressure-sensitive adhesive for optical films, comprising applying the pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 16 onto a release sheet that has been subjected to a release treatment, and then heat-treating to cause a cross-linking reaction. Layer manufacturing method. The method for producing an optical film pressure-sensitive adhesive layer according to claim 24, wherein the temperature of the heat treatment is 80°C or higher and 120°C or lower.