JP7291475B2 - OPTICAL FILM ADHESIVE, ADHESIVE LAYER, OPTICAL MEMBER, AND IMAGE DISPLAY DEVICE - Google Patents

Description

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

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

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.

On the other hand, recently, cheaper and thinner polarizing plates have been desired. As one form thereof, conventionally, a single-sided protective polarizing plate using only one protective film on one side of a polarizer has been proposed, in contrast to a double-sided protective polarizing plate in which both sides of a polarizer are laminated with protective films. However, unlike the conventional double-sided protective polarizing plate, it is known that the single-sided protective polarizing plate shrinks significantly during durability, particularly heat durability and heat shock cycle tests.

Therefore, this single-sided protective polarizing plate is required to have the same durability as the conventional double-sided protective polarizing plate. It is required to suppress air bubbles generated at the edge of the plate. In order to suppress the formation of air bubbles at the edges of the polarizing plate, it is effective to use a silane coupling agent having multiple isocyanate groups, which can improve wettability to glass while functioning as a cross-linking agent. It is believed that there are

The pressure-sensitive adhesive containing a silane coupling agent having an isocyanate group includes at least one component selected from a pressure-sensitive adhesive component (A), a silane coupling agent (B) having an isocyanate group, a cross-linking agent and a curing agent. A pressure-sensitive adhesive containing (C) has been proposed (see, for example, Patent Document 1).

Further, as another invention, a polymer [P] having a glass transition temperature of −80° C. or more and 10° C. or less having at least one of a carboxyl group and a hydroxyl group, a silane compound (f2) having an isocyanate group and an alkoxysilyl group, Reaction product (F) with polyol (f1), which reaction product (F) contains hydroxyl groups and alkoxysilyl groups, and reaction capable of reacting with at least one of carboxyl groups and hydroxyl groups in the polymer [P] A pressure-sensitive adhesive characterized by containing a chemical compound (G) has been proposed (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2013-209600 JP 2009-280776 A

However, according to the inventor's examination, it was also found that there are the following problems. In Patent Document 1, a silane coupling agent having an isocyanate group can improve wettability to glass and function as a cross-linking agent at the same time when it has one isocyanate group or does not have an isocyanurate skeleton. do not have. Also, when there are a plurality of isocyanate groups, the crosslink density is too high when used as a crosslinker. Therefore, in any case, it was found that there was a problem that bubbles generated at the edge of the polarizing plate during the durability test could not be suppressed. Furthermore, it was found that there was a problem that the reworkability (workability) was not sufficient.

Moreover, in Patent Document 2, the silane coupling agent having an isocyanate group has one isocyanate group. When there is only one isocyanate group, it is impossible to achieve both the improvement of wettability to glass and the function as a cross-linking agent. For this reason, it has been found that there is a problem that both the occurrence of peeling and floating during the durability test and the formation of air bubbles at the edges of the polarizing plate cannot be suppressed. Furthermore, it was found that there was a problem that the reworkability (workability) was not sufficient.

The present invention has been made in view of the above circumstances. That is, even when used as a single-sided protective polarizing plate, durability in harsh environments (high temperature, high humidity, heat shock) (in particular, suppression of peeling and floating of the polarizing plate and It is an object of the present invention to provide a pressure-sensitive adhesive for an optical film, which can suppress the generation of air bubbles and improve reworkability (workability).

The present inventor has made intensive studies to solve the above problems. As a result, the inventors have found that the above problems can be solved by a pressure-sensitive adhesive containing a silane coupling agent having a plurality of isocyanate groups having a specific structure, and have completed the present invention.

That is, the present invention provides an optical film pressure-sensitive adhesive comprising a polymer component (A) having a hydroxyl group and a silane coupling agent (B) having a plurality of isocyanate groups,
The silane coupling agent (B) having a plurality of isocyanate groups contains at least one compound selected from the group consisting of compounds represented by the following general formulas 1 to 4 containing an isocyanurate skeleton. It is a pressure-sensitive adhesive for optical films characterized by:

In the general formula 1,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁴ are each independently an alkylene group having 1 to 8 carbon atoms,
Y ¹ is a group represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 2,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁶ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 3,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁵ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In the general formula 4,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁹ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ and R ¹⁰ are each independently an alkylene group having 1 to 16 carbon atoms,
Y ¹ , Y ² and Y ³ are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In Formula 5, * means a portion connected to another atom (adjacent atom).

According to the present invention, even when used in a single-sided protective polarizing plate, durability in harsh environments (high temperature, high humidity, heat shock) (in particular, suppression of bubbles generated at the edge of the polarizing plate, and Provided is a pressure-sensitive adhesive for an optical film that can improve the suppression of peeling of a polarizing plate and is also excellent in reworkability (processability).

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

[Adhesive for optical films]
The pressure-sensitive adhesive for optical films of the present invention is a pressure-sensitive adhesive for optical films containing a polymer component (A) having a hydroxyl group and a silane coupling agent (B) having a plurality of isocyanate groups,
The (B) silane coupling agent having a plurality of isocyanate groups contains at least one compound selected from the group consisting of compounds represented by the following general formulas 1 to 4 containing an isocyanurate skeleton. It is characterized by

In the general formula 1,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁴ are each independently an alkylene group having 1 to 8 carbon atoms,
Y ¹ is a group represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 2,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁶ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 3,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁵ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In the general formula 4,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁹ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ and R ¹⁰ are each independently an alkylene group having 1 to 16 carbon atoms,
Y ¹ , Y ² and Y ³ are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In Formula 5, * means a portion connected to another atom (adjacent atom).

According to the pressure-sensitive adhesive for optical films of the present invention having such a configuration, even when used for a single-sided protective polarizing plate, it exhibits durability in harsh environments (high temperature, high humidity, heat shock) (particularly, (Suppression of air bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) can be improved, and reworkability (processability) is also excellent.

Recently, cheaper and thinner polarizers are desired. As one form thereof, a single-side protective polarizing plate using only one protective film on one side of a polarizer has been proposed. In the single-sided protective polarizing plate, the force of the protective film to suppress shrinkage of the polarizer is reduced. As a result, the present inventors have found that shrinkage due to heating or the like is likely to occur, and in particular, there is a problem that air bubbles are likely to be generated at the edges of the polarizing plate. Therefore, the inventors have made extensive studies to solve this problem. As a result, by using a polymer component (A) having a hydroxyl group and a pressure-sensitive adhesive containing a silane coupling agent (B) having a plurality of isocyanate groups (NCO) having a specific structure, the above problems can be solved. Found it. By using the silane coupling agent (B) having a plurality of isocyanate groups having a specific structure, wettability to glass and a cross-linking effect by a plurality of NCOs can be achieved at the same time. Furthermore, it has an NCO crosslinked structure and can ensure flexibility. Therefore, the effect of cross-linking is large and the stress relaxation property is not impaired, and even if the protective film suppresses shrinkage of the polarizer in the single-sided protective polarizing plate, shrinkage due to heating or the like can be suppressed. . As a result, it is possible to suppress the generation of air bubbles at the edges and to suppress peeling and floating of the polarizing plate. That is, by using a polymer component (A) having a hydroxyl group and an adhesive containing the silane coupling agent (B) described above, durability in harsh environments (high temperature, high humidity, heat shock) (especially polarized light The present inventors have found that it is possible to obtain a pressure-sensitive adhesive that can improve the suppression of air bubbles generated at the edge of the plate and the suppression of peeling of the polarizing plate, and also has excellent reworkability (processability).

Note that the above mechanism is based on speculation, and the present invention is in no way limited to the above mechanism.

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

In addition, in this specification, "(meth)acrylic acid ester" is a general term for acrylic acid ester and methacrylic acid ester. Similarly, compounds containing (meth) such as (meth)acrylamide are collective names for compounds having "meta" in their names and compounds not having "meta" in their names. In addition, the "(meth)acrylic acid ester copolymer (A1)" is also simply referred to as "copolymer (A1)".

<Polymer Component (A) Having a Hydroxyl Group>
The optical film pressure-sensitive adhesive according to the present invention essentially contains a polymer component (A) having a hydroxyl group. As the polymer component (A) having a hydroxyl group, a hydroxyl group-containing unsaturated compound or a homopolymer such as an unsaturated compound containing a polar group capable of introducing or generating a hydroxyl group by some chemical modification after polymerization, etc. and at least one (co)polymer selected from the group consisting of a copolymer with a polymerizable monomer and a graft polymer to another polymer, and as a result, structurally branched or linear hydroxyl groups are randomly or regularly pendant to the molecular chain, or from oligomers to polymers having a structure in which side chains having hydroxyl groups are grafted.

The polymer component (A) can be produced by a well-known method. For example, a method of polymerizing a hydroxyl group-containing unsaturated compound, a method of copolymerizing a hydroxyl group-containing unsaturated compound with another polymerizable monomer, a method of grafting a hydroxyl group-containing unsaturated compound onto a polymer, a diol compound to a polar group in the polymer, Examples include a method of reacting a polyol compound, an epoxy-containing compound, or a compound having at least one hydroxyl group with a functionality of two or more, and a method of generating a hydroxyl group by chemical reaction such as oxidation or hydrolysis of a polar group in a polymer. be able to. Among the polymers produced by the above production methods and the like, the (meth)acrylic acid ester copolymer (A1) is preferred as shown below. The preferred copolymer (A1) will be described in detail below.

<(Meth) acrylic acid ester copolymer (A1)>
The polymer component (A) having a hydroxyl group is preferably a (meth)acrylate copolymer (A1).

The weight average molecular weight (Mw) of the copolymer (A1) measured by gel permeation chromatography (GPC) is preferably 500,000 or more and 2,000,000 or less. The following effects can be obtained by cross-linking the copolymer (A1) having a high molecular weight within the above range with the silane coupling agent (B) having a plurality of isocyanate groups having a specific structure. That is, the effect of cross-linking is large, and the stress relaxation property is not impaired. Therefore, even if the protective film suppresses shrinkage of the polarizer in the single-sided protective polarizing plate, shrinkage due to heating or the like can be suppressed. As a result, it is possible to suppress the generation of air bubbles at the edges and to suppress peeling and floating of the polarizing plate, thereby significantly improving the durability under harsh environments. A weight-average molecular weight (Mw) of 500,000 or more is preferable in terms of preventing deterioration in durability at high temperatures and reworkability after heating. On the other hand, if it is 2,000,000 or less, the amount of gel components in the polymer solution is small, and coating properties are not deteriorated due to an increase in coating liquid viscosity during coating, which is preferable.

The weight average molecular weight (Mw) of the copolymer (A1) measured by GPC is more preferably 900,000 or more and 1,500,000 or less, further preferably 1,000,000 or more and 1,500,000 or less. If the weight-average molecular weight (Mw) of the copolymer (A1) is within the above range, the durability in severe environments (high temperature, high humidity, heat shock) can be further improved. A person skilled in the art can easily control the weight average molecular weight (Mw) of the copolymer (A1). For example, it can be controlled by appropriately adjusting reaction conditions such as the type and/or amount of the polymerization initiator used in the polymerization reaction described below, the reaction temperature, and the reaction time.

In addition, the weight average molecular weight (Mw) of the copolymer (A1) can be measured by GPC, and in detail, it can be measured by the method shown in Examples.

In the present invention, as structural units constituting the copolymer (A1),
(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)").
It preferably contains That is, the copolymer (A1) preferably contains component (a1) and component (a2); it also preferably contains component (a1) and component (a3); further component (a1) and component (a2) , and component (a3).

In this specification, for example, "the copolymer X contains a structural unit derived from the monomer Y1 and a structural unit derived from the monomer Y2" means that when the copolymer X is obtained by copolymerization, the raw material used As a monomer, it is meant to include monomer Y1 and monomer Y2.

Hereinafter, structural units derived from respective monomers that can constitute the copolymer (A1) will be described in order.

[(a1) structural unit derived from alkyl (meth)acrylate monomer]
The copolymer (A1) preferably contains (a1) a structural unit derived from an alkyl (meth)acrylate monomer (hereinafter also simply referred to as "component (a1)"). Such a component (a1) is considered to be significant in ensuring adhesiveness and basic properties by being included as a structural unit of the (meth)acrylate copolymer (A1).

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 from 1 to 18, more preferably from 1 to 12, still more preferably from 1 to 10, even more preferably from 1 to 8, and from 1 to 6. is particularly preferred. If the number of carbon atoms in the alkyl group is within the above range, it is preferable from the viewpoint of versatility, price, handling, and the like. Also, the alkyl group may be linear, branched, or cyclic. From the viewpoint of lowering the glass transition temperature, the alkyl group is preferably linear or branched. 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 the component (a1) in the copolymer (A1) (amount of the alkyl (meth)acrylate monomer as a raw material monomer) is not particularly limited, but constitutes the (meth)acrylate copolymer (A1). It is preferably 64.5% by mass or more and less than 99.5% by mass, 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, relative to 100% by mass of the total amount of the structural units. If the content of the component (a1) in the copolymer (A1) is within the above range, it is preferable from the viewpoints of a good balance with the content of the other raw material monomers described below, improved durability, and the like. In the present specification, "100% by mass of the total amount of structural units constituting the (meth)acrylate copolymer (A1)" 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 (A1) preferably contains (a2) a structural unit derived from a (meth)acrylate monomer having a hydroxyl group (hereinafter also simply referred to as "component (a2)"). Such component (a2) is highly reactive with the silane coupling agent (B) and the cross-linking agent. Therefore, it is considered that inclusion as a structural unit of the copolymer (A1) has significance in improving cohesion, heat resistance, and durability of the pressure-sensitive adhesive layer, which will be described later. In addition, the component (a2) portion of the copolymer (A1) can react with at least one component (C) selected from silane coupling agents (B), cross-linking agents and curing agents. Therefore, the cross-linking density of the pressure-sensitive adhesive layer, which will be described later, increases, the pressure-sensitive adhesive layer becomes hard, and the amount of deformation of the pressure-sensitive adhesive layer during re-peeling becomes small. It has been found that this reduces the adhesive strength, provides desirable reworkability, and suppresses peeling and lifting in terms of durability.

In the present invention, the structure of the (meth)acrylate monomer having a hydroxyl group is not particularly limited as long as the 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 (A1) 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) constitutes the copolymer (A1) It is preferably 0.01% by mass or more and 10% by mass or less with respect to 100% by mass of the total amount of the constituent units. When the content of the component (a2) is 0.01% by mass or more, the number of cross-linking reaction sites does not become too small, and durability can be improved, which is preferable. On the other hand, when the content of the component (a2) is 10% by mass or less, the ratio of the polar monomer to be blended does not become relatively large, and the polarity of the pressure-sensitive adhesive layer formed does not become too high. It is preferable in terms of improving durability. The content of component (a2) is more preferably 0.3% by mass or more and 5% by mass or less, and even 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 (A1) 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 for optical films.

In the present invention, the structure of the monomer having a carboxyl group may have any structure as long as it contains a carboxyl group and a polymerizable unsaturated bond.

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 (A1) 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) constitutes the copolymer (A). It is preferably 0.01% by mass or more and 7% by mass or less with respect to 100% by mass of the total amount of the constituent units. When the content of component (a3) is 0.01% by mass or more, the number of cross-linking reaction sites does not become too small, and durability is improved, which is preferable. On the other hand, when the content of the component (a3) is 7% by mass or less, the ratio of the polar monomers to be blended does not become too high, and the polarity of the formed pressure-sensitive adhesive layer does not become too high, resulting in durability. It is preferable in terms of improving the properties. The content of component (a3) is more preferably 0.2% by mass or more and 5% by mass or less, and even more preferably 0.6% by mass or more and 5% by mass or less.

[(a4): constituent units derived from monomers other than components (a1) to (a3)]
The copolymer (A) according to the present invention includes, as an optional component, a monomer other than the components (a1) to (a3) that can be copolymerized with the components (a1) to (a3) described above (hereinafter simply referred to as "component ( a4)”) can be included.

As component (a4), known components can be used as long as they do not impair the effects of the present invention. For example, a structural unit derived from a (meth)acrylate monomer having an aromatic ring can be used as component (a4). The structure of the (meth)acrylate monomer having an aromatic ring may have any structure as long as it contains an aromatic ring (aromatic ring) and a (meth)acryloyl group. 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.

Furthermore, as the component (a4), in addition to the structural unit derived from the (meth)acrylate monomer having an aromatic ring as described above, as the raw material monomer for the component (a4), as long as the effects of the present invention are not impaired, known monomers are used. can be used.

Examples of raw material monomers for component (a4) 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 (a4).

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-ethylhexyl-diglycol (meth) acrylate (2-ethylhexyloxy-diethylene 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. Moreover, it is preferable that the raw material monomer of the component (a4) does not contain olefinic monomers such as ethylene and propylene. This facilitates the reaction with at least one component (C) selected from a silane coupling agent (B), a crosslinking agent, and a curing agent, which will be described later, when producing the (meth)acrylate copolymer (A1). This is because it is possible to control Moreover, it is because a molecular weight cannot become high easily.

The content of the structural unit derived from the component (a4) in the copolymer (A1) is 0.00 parts per 100 parts by mass in total of the structural units derived from the component (a1), the component (a2), and the component (a3). It is preferably 01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass.

[Method for producing (meth)acrylate copolymer (A1)]
Next, a method for producing the copolymer (A1) will be described. In the present invention, the method for producing the copolymer (A1) is not particularly limited. Conventionally known methods such as a thin film polymerization method and 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. This is 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 that is a raw material for the copolymer (A1), for example, a raw material monomer solution containing the above-described 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. do. After that, a method of reacting for 3 hours or more and 10 hours or less at a reaction temperature of 40° C. or more and 90° C. or less (or 60° C. or more and 90° C. or less) in a nitrogen atmosphere can be used.

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. After that, an active energy ray is applied 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 terminated by introducing air into the reaction system, and a method of obtaining the copolymer (A1) is exemplified. .

Examples of active energy rays used in bulk polymerization include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron beams. Ultraviolet rays are preferably used as the active energy rays from the viewpoints of controllability, ease of handling, and cost. 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 (manufactured by BASF Japan Co., Ltd.), Ezacure (registered trademark) KIP150, TZT (manufactured by DKSH Japan Co., Ltd.), Kayacure (registered trademark) BMS, DMBI (manufactured by Nippon Kayaku Co., Ltd.), etc. is 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 (A1). 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.

<Silane coupling agent having multiple isocyanate groups (B)>
The pressure-sensitive adhesive for optical films of the present invention contains a silane coupling agent (B) having multiple isocyanate groups. Furthermore, the (B) silane coupling agent having a plurality of isocyanate groups contains at least one compound selected from the group consisting of compounds represented by the following general formulas 1 to 4 containing an isocyanurate skeleton. It is a thing. In the present invention, the following effects are obtained by using the silane coupling agent (B) having a plurality of isocyanate groups having a specific structure. In other words, the wettability to glass and the cross-linking effect of a plurality of NCOs can be realized at the same time. Furthermore, it has an NCO crosslinked structure and can ensure flexibility. Therefore, the effect of cross-linking is large, and the stress relaxation property is not impaired. Therefore, even if the protective film suppresses shrinkage of the polarizer in the single-sided protective polarizing plate, shrinkage due to heating or the like can be suppressed. As a result, it is possible to suppress the generation of air bubbles at the edges and to suppress peeling and floating of the polarizing plate. Furthermore, it is possible to improve durability (especially suppression of air bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) under harsh environments (high temperature, high humidity, heat shock), and reworkability ( It is possible to provide an adhesive that is also excellent in workability). 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 general formula 1,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁴ are each independently an alkylene group having 1 to 8 carbon atoms,
Y ¹ is a group represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 2,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁶ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less.

In the general formula 3,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁵ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In the general formula 4,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁹ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ and R ¹⁰ are each independently an alkylene group having 1 to 16 carbon atoms,
Y ¹ , Y ² and Y ³ are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less.

In Formula 5, * means a portion connected to another atom (adjacent atom).

R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms. From the viewpoint of ensuring both the effect as a cross-linking agent and the stress relaxation effect, it is preferably an alkyl group having 1 or more and 6 or less carbon atoms, more preferably 1 or more and 4 or less carbon atoms.

R ³ , R ⁵ , R ⁶ and R ⁹ are each independently an alkylene group having 1 or more and 8 or less carbon atoms. From the viewpoint of ensuring both the effect as a cross-linking agent and the effect of stress relaxation, it is preferably an alkylene group having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms.

R ⁴ in General Formula 1 above is an alkylene group having 1 to 8 carbon atoms. From the viewpoint of ensuring both the effect as a cross-linking agent and the effect of stress relaxation, it is preferably an alkylene group having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms.

R ⁴ and R ¹⁰ in general formulas 2 to 4 above each independently represent an alkylene group having 1 or more and 16 or less carbon atoms. From the viewpoint of ensuring both the effect as a cross-linking agent and the stress relaxation effect, it is preferably an alkylene group having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms.

The above n and m are each independently an integer of 1 or more and 8 or less. It is preferably an integer of 1 or more and 6 or less, more preferably 1 or more and 4 or less, from the viewpoint of ensuring both the effect as a cross-linking agent and the effect of stress relaxation.

The above a and b are each independently an integer of 0 or more and 3 or less, preferably an integer of 0 or more and 2 or less, more preferably 0 or more and 1 or less, from the viewpoint of ensuring affinity with glass.

The silane coupling agent (B) preferably contains at least one compound selected from the group consisting of compounds represented by the following general formulas 1a to 4a. The use of these compounds is excellent in that the effects of the invention described above can be further improved.

As the silane coupling agent (B), a commercially available product or a synthetic product may be used. Examples of commercially available silane coupling agents (B) include X-12-1159L (manufactured by Shin-Etsu Chemical Co., Ltd.).

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

The content of the silane coupling agent (B) is preferably 0.001 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymer component (A) having a hydroxyl group. It is more preferably not more than 0.01 part by mass and even more preferably 0.01 part by mass or more and 3 parts by mass or less. When the content of the silane coupling agent (B) 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 of the silane coupling agent (B) is 10 parts by mass or less, it is preferable from the viewpoint that deterioration of thermal foaming caused by the low-molecular-weight compound is eliminated.

The silane coupling agent (B) can be produced by a well-known method. Hereinafter, the synthesis of general formula 1a will be described as an example, but the production method is not limited to this.

A reaction vessel equipped with a stirrer, a thermometer and a cooling tube is purged with nitrogen, and hexamethylene diisocyanate (HDI) and 3-isocyanatopropyltriethoxysilane are charged at a molar ratio of 2:1. Next, an appropriate amount of an isocyanurate catalyst (eg, tetramethylammonium capriate) is added while heating (eg, at 70° C.) with stirring. When the conversion rate reaches 25% by measuring the refractive index of the reaction solution, an appropriate amount of phosphoric acid is added to stop the isocyanurate reaction. Furthermore, the resulting isocyanurate-type polyisocyanate composition is heated (for example, heated at 100° C. for 150 minutes).

Subsequently, the isocyanurate-type polyisocyanate composition is filtered. Thereafter, unreacted HDI monomer and a portion of 3-isocyanatopropyltriethoxysilane are removed by first thin film distillation under heating and reduced pressure conditions (eg, 160° C., 0.8 mmHg). The content of the HDI monomer and 3-isocyanatopropyltriethoxysilane in the triethoxysilyl group-containing isocyanurate-type polyisocyanate composition after the first thin-film distillation is around 10% by mass. The isocyanurate-type polyisocyanate composition after the first thin-film distillation is heat-treated (for example, heat-treated at a temperature of 120° C. for 60 minutes). Excess HDI monomer is then removed by a second thin film distillation under heating and reduced pressure conditions (eg, 160° C., 0.1 mmHg). The content of the HDI monomer in the isocyanurate-type polyisocyanate composition after the second thin film distillation is around 0.10% by mass. The isocyanurate-type polyisocyanate composition after the second thin-film distillation is heat-treated (for example, heat-treated at a temperature of 90° C. for 180 minutes). As a result, the triethoxysilyl group-containing isocyanurate-type polyisocyanate (silane coupling agent (B)) represented by the general formula 1a is obtained.

<At least one component (C) selected from a crosslinking agent and a curing agent capable of reacting with the polymer component (A) having a hydroxyl group>
The pressure-sensitive adhesive for optical films of the present invention comprises at least one component (C) selected from a cross-linking agent and a curing agent capable of reacting with the polymer component (A) having a hydroxyl group (hereinafter referred to as "cross-linking agent/curing agent component (C )”) is preferably included. The cross-linking agent/curing agent component (C) reacts with the hydroxyl-containing polymer component (A) to form a cross-linked structure. Therefore, the cross-linking agent/curing agent component (C) can mainly contribute to adhesiveness (tackiness) and durability in the pressure-sensitive adhesive for optical films.

In the present invention, the cross-linking agent/curing agent component (C) is at least one selected from the group consisting of isocyanate compounds, carbodiimide compounds, oxazoline compounds, epoxy compounds, polyfunctional (meth)acrylic acid ester monomers, and peroxides. It is more preferred to contain seeds. These various cross-linking agent/curing agent components (C) are described below.

[Isocyanate compound]
In the present invention, specific examples of the isocyanate compound used as the crosslinking agent/curing agent component (C) include dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tri diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xyl Aromatic diisocyanates such as diisocyanate (XDI), tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI); hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI) ), lysine diisocyanate, norbornane diisocyanate methyl (NBDI) and other aliphatic diisocyanates; transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12-MDI (hydrogenated alicyclic diisocyanates such as MDI); carbodiimide-modified diisocyanates of the above diisocyanates; or isocyanurate-modified diisocyanates thereof. Adducts of the above isocyanate compounds and polyol compounds such as trimethylolpropane, polytetramethylene ether glycol (PTMG) and polypropylene glycol (PPG), and biuret and isocyanurate of these isocyanate compounds can also be suitably used.

These isocyanate compounds may be commercially available products or synthetic products.

Commercially available products include, for example, Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, Coronate (registered trademark) 2031 (manufactured by Tosoh Corporation), 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 TPA-100, Duranate TKA-100, Duranate P301-75E, Duranate E402-90T, Duranate E405-80T, Duranate (registered trademark) TSE-100, Duranate (registered trademark) D-101, Duranate (registered trademark) D-201 (manufactured by Asahi Kasei Corporation), Sumidule (registered trademark) N-75, N-3200, N- 3300 (manufactured by Sumika Covestro Urethane Co., Ltd.), Sampren (registered trademark) P-6090 (PTMG/MDI system), Sampren (registered trademark) P-663L (PTMG/TDI system), Sampren (registered trademark) P -664 (PTMG/TDI system), Samplen (registered trademark) P-665 (PTMG/TDI system), Samplen (registered trademark) P-667 (PTMG/TDI system), Samplen (registered trademark) P-868 (PTMG/ HMDI-based), Sampren (registered trademark) P-870 (PTMG/HMDI-based), Sampren (registered trademark) C-810 (PPG/TDI-based) (manufactured by Sanyo Chemical Industries, Ltd.), and the like. It is not limited to these.

The isocyanate compound may be used in the form of an unblocked isocyanate compound. Also, the isocyanate compound may be used in the form of a blocked isocyanate compound obtained by reacting with a blocking agent that protects the isocyanate group. Such blocked isocyanate compounds may be commercially available products or synthetic products. Examples of commercially available blocked isocyanate compounds include Duranate (registered trademark) MF-B60X (block 1,6-hexamethylene diisocyanate) and Duranate (registered trademark) MF-K60X (block 1,6-hexamethylene diisocyanate) manufactured by Asahi Kasei Corporation. methylene diisocyanate), Tosoh Corporation Coronate (registered trademark) AP-M, 2503, 2507, 2513, 2515, Millionate (registered trademark) MS-50, Mitsui Chemicals, Inc. Takenate (registered trademark) B-830 ( blocked tolylene diisocyanate), B-815N (block 4,4′-methylenebis(cyclohexyl isocyanate)), B-842N (block 1,3-bis(isocyanatomethyl)cyclohexane), B-846N (block 1, 3-bis(isocyanatomethyl)cyclohexane), B-874N (blocked isophorone diisocyanate), B-882N (blocked 1,6-hexamethylene diisocyanate), DIC Corporation Barnock (registered trademark) ) D-500 (blocked tolylene diisocyanate), D-550 (blocked 1,6-hexamethylene diisocyanate), Elastron (registered trademark) BN-P17 (blocked 4,4'-diphenylmethane diisocyanate), BN-04, BN-08, BN-44, BN-45 (these are block urethane-modified polyvalent isocyanates) and the like. Among these, Duranate (registered trademark) MF-K60X is preferred.

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

Further, the isocyanate compound according to the present invention preferably has a number average molecular weight (Mn) of 900 or more and 10,000 or less. By including the isocyanate compound having such a number average molecular weight as the cross-linking agent/curing agent component (C), the following effects are obtained. That is, it is possible to exhibit a moderate cross-linking effect due to the long distance between the cross-linking points while suppressing the density of the cross-linked structure of the polymer component (A) having hydroxyl groups. As a result, it is possible to more efficiently achieve both suppression of end air bubbles and suppression of peeling.

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

From the viewpoint of further exerting the effects of the present invention, the number average molecular weight (Mn) of the isocyanate compound is more preferably 900 or more and 7,000 or less, and more preferably 1,000 or more and 5,000 or less. preferable. The number average molecular weight (Mn) of the isocyanate compound can be determined by the same method as the method for measuring the weight average molecular weight of the copolymer (A1) shown in Examples.

[Carbodiimide compound]
In the present invention, the carbodiimide compound used as the cross-linking agent/curing agent component (C) is not particularly limited. An example of a carbodiimide compound is a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of a diisocyanate in the presence of a carbodiimidation catalyst.

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.

Commercially available products or synthesized products may be used as the high-molecular-weight polycarbodiimide. 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 compound]
In the present invention, the oxazoline compound used as the cross-linking agent/curing agent component (C) is not particularly limited. The oxazoline compound includes an oxazoline group-containing acrylic/styrene polymer having a main chain consisting of an acrylic skeleton or a styrene skeleton and having an oxazoline group in the side chain of the main chain, or a main chain consisting of an acrylic skeleton, Oxazoline group-containing polymers, such as oxazoline group-containing acrylic polymers having oxazoline groups in the side chains of the main chain, are preferred.

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 compound]
In the present invention, the epoxy compound used as the cross-linking agent/curing agent component (C) is not particularly limited, and a known epoxy-based cross-linking agent can be appropriately employed. Examples of commercially available epoxy compounds 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. ”, “ADEKA RESIN (registered trademark) EPR series”, and liquid epoxy resins such as “Celoxide (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 for optical films.

[Polyfunctional (meth)acrylic acid ester monomer]
A polyfunctional (meth)acrylate monomer is a (meth)acrylate monomer having a plurality of radically polymerizable functional groups. Such a compound can also be used as the cross-linking agent/curing agent component (C).

Polyfunctional (meth)acrylic acid ester monomers include, for example, hydrocarbon-based or hydrocarbon ether-based multifunctional monomers. The hydrocarbon-based or hydrocarbon-ether-based polyfunctional monomer is a compound obtained by (meth)acrylating the hydroxy group of a polyhydric alcohol having a main skeleton of a hydrocarbon group or a hydrocarbon ether group having 10 to 100 carbon atoms. be. These are preferable from the viewpoint of improving adhesiveness by cross-linking. The hydrocarbon group of the polyhydric alcohol includes linear or branched aliphatic hydrocarbon groups, aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and hydrocarbon groups in which these hydrocarbon groups are combined. . Examples of the hydrocarbon ether group include etherified hydrocarbon groups. Further, as the polyhydric alcohol having a hydrocarbon ether group as a main skeleton, a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to the above polyhydric alcohol (addition number 1 to 30), etc. Examples thereof include polyalkylene glycols obtained from 4 or less alkylene oxides (addition number is 1 or more and 30 or less).

Specific examples of the hydrocarbon-based bifunctional monomer include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediyl di(meth)acrylate, ) acrylate, di(meth)acrylate of alkylene glycol such as neopentyl glycol di(meth)acrylate; alicyclic carbonization such as cyclohexane dimethanol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate di(meth)acrylates of diol compounds having a hydrogen group; and di(meth)acrylates of diol compounds having an aromatic hydrocarbon group such as bisphenol A di(meth)acrylate.

Further, specific examples of hydrocarbon ether-based bifunctional monomers include alkoxylated hexanediol di(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate, and alkoxylated di(meth)acrylate. , alkoxylated neopentyl glycol di (meth) acrylate, alkoxylated bisphenol A di (meth) acrylate, etc. Di ( meth)acrylate and the like. Further, specific examples of hydrocarbon ether-based bifunctional monomers include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, Polyalkylene glycol di(meth)acrylates such as tripropylene glycol di(meth)acrylate and dipropylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, and the like can be mentioned.

Examples of hydrocarbon-based or hydrocarbon-ether-based trifunctional monomers and tetrafunctional monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glyceryl tri(meth)acrylate, Tri(meth)acrylates or tetra(meth)acrylates of tri- or tetraol compounds such as pentaerythritol tetra(meth)acrylate and trimethylolpropane tetra(meth)acrylate, and compounds obtained by adding alkylene oxide to the above tri- or tetraol compounds and tri(meth)acrylate or tetra(meth)acrylate.

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

[Peroxide]
In the present invention, the peroxide used as the cross-linking agent/curing agent component (C) is not particularly limited, and known peroxides can be used. The peroxide preferably has a 1-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. °C or higher and 125 °C or lower are more preferred, and those that are 90 °C or higher and 125 °C or lower are particularly preferred. 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 include 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.), bis(4-t-butylcyclohexyl) peroxydicarbonate (92.1° C.), di-sec-butyl peroxydicarbonate (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), a mixture of dibenzoyl peroxide, benzoyl m-methylbenzoyl peroxide and m-toluoyl peroxide ( 131.1°C), t-butyl peroxybutyrate (136.1°C), and the like. Among them, diisopropyl peroxydicarbonate, bis(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 using two or more kinds in combination, a combination of di(4-t-butylcyclohexyl)peroxydicarbonate and dilauroyl peroxide is suitable.

A commercially available product or a synthetic product may be used as the peroxide. 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 crosslinking agent/curing agent component (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/curing agent components (C) (for example, two types of isocyanate compounds) may be combined, or different types of cross-linking/curing agent components (C ) (for example, one isocyanate compound and one peroxide) may be combined.

The content of the crosslinking agent/curing agent component (C) in the pressure-sensitive adhesive for optical films 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 polymer component (A) having a hydroxyl group. 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. When the content of the cross-linking agent/curing agent component (C) is 0.001 parts by mass or more, it is preferable from the viewpoint that foaming can be suppressed during heat durability. On the other hand, when the content of the cross-linking agent/curing agent component (C) is 20 parts by mass or less, the cross-linked structure does not become too dense, and durability can be ensured even in harsh environments, which is preferable.

<Silane coupling agent (D) containing no isocyanate group>
Preferably, the pressure-sensitive adhesive for optical films of the present invention further contains a silane coupling agent (D) containing no isocyanate group. The silane coupling agent (D) containing no isocyanate group can mainly contribute to improvement in durability and adhesion to glass when the adherend is glass in the pressure-sensitive adhesive for optical films.

In the present invention, the silane coupling agent (D) containing no isocyanate group is not particularly limited, but specific examples include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyltriethoxysilane, Methoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyl trimethoxysilane, diphenyldimethoxysilane, cyclohexylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane , 3-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, 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, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane and the like. 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 each functional group with a ring agent, other coupling agent, or the like in an arbitrary ratio can also be used.

As the isocyanate group-free silane coupling agent (D), a commercially available product or a synthetic product may be used. Examples of commercially available silane coupling agents (D) include KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, and KBM-802. , KBM-803, and KBE-846 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The isocyanate group-free silane coupling agent (D) may be used alone or in combination of two or more.

When the pressure-sensitive adhesive for optical films of the present invention contains a silane coupling agent (D) containing no isocyanate group, the content of the silane coupling agent (D) is not particularly limited, but the polymer component (A ) With respect to 100 parts by mass, it is preferably 0.001 to 10 parts by mass, more preferably 0.001 to 5 parts by mass, and 0.01 to 3 parts by mass More preferably: When the content of the silane coupling agent (D) containing no isocyanate group 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 of the silane coupling agent (D) containing no isocyanate group is 10 parts by mass or less, it is preferable from the viewpoint of eliminating deterioration of thermal foaming caused by low-molecular-weight compounds.

<Other additive ingredients>
The optical film pressure-sensitive adhesive of the present invention may optionally contain known additive components (other additive components) within a range that does not impair the effects of the present invention. Examples of known additive components include, but are not limited to, solvents, cross-linking accelerators, anti-aging agents, fillers, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, chain transfer agents, and plasticizers. , softeners, surfactants, antistatic agents, and the like.

<Solvent>
The pressure-sensitive adhesive for optical films of the present invention may contain a solvent. By including a solvent, a significant improvement in productivity during coating can be obtained. The solvent is not particularly limited, but esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane; 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.

<Manufacturing (preparing) method of adhesive for optical film>
When the pressure-sensitive adhesive for an optical film according to the present invention contains a polymer component (A) having a hydroxyl group and a component other than the polymer component (A) having a hydroxyl group, it can be prepared by mixing each component. The mixing order and mixing temperature of each component are not particularly limited, and can be appropriately adjusted by those skilled in the art.

[Use]
The pressure-sensitive adhesive for optical films of the present invention described above is suitable for various uses. For example, it is preferably used for 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. Examples of 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 by the pressure-sensitive adhesive for optical films described above, the form of the optical member formed by forming the pressure-sensitive adhesive layer on an optical film or the like, the form of the optical film being a polarizing plate, Alternatively, a mode of applying the optical member 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 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 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 the application. The thickness of the adhesive layer is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 75 μm or less, still more preferably 5 μm or more and 40 μm or less, particularly preferably 7 μm or more and 35 μm or less, most preferably It is 10 μm or more and 30 μm or less. When the thickness of the pressure-sensitive adhesive layer is within the above range, it 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 the silane coupling agent (B), the amount of the cross-linking agent, and the amount of the peroxide.

[Method for producing pressure-sensitive adhesive layer]
According to another aspect of the present invention, a method for producing a pressure-sensitive adhesive layer for an optical film, comprising applying the pressure-sensitive adhesive for an optical film of the present invention described above onto a release sheet, followed by heat treatment to cause a cross-linking reaction. is also provided.

When using an adhesive for the optical film, the adhesive may be applied directly onto the optical film to form an adhesive layer. Above all, it is desirable to apply the pressure-sensitive adhesive on a film having releasability to form a pressure-sensitive adhesive layer, and then transfer it to various optical films for use. In addition, the releasable film with the pressure-sensitive adhesive layer thus produced can also be wound together in the production process to form a roll. Furthermore, after being formed into a roll shape, it is cut or processed as necessary, and when it is attached to various optical films, liquid crystal panels, etc., the film having releasability can be removed and used. 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. suitable thin leaf bodies, etc. can be mentioned. A plastic film is preferably used as a constituent material of the release sheet 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 release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. This is because the releasability from the pressure-sensitive adhesive layer can be further enhanced.

In the present invention, there are no particular restrictions on the method of applying the pressure-sensitive adhesive for optical films of the present invention onto a release sheet, and various known methods can be 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 for optical films 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-mentioned pressure-sensitive adhesive 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 or more and 20 minutes or less, more preferably 5 seconds or more and 10 minutes or less, and still more preferably 10 seconds or more and 5 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 comprising the optical film pressure-sensitive adhesive layer described above and a first optical film provided on one surface of the pressure-sensitive adhesive layer.

Further, according to one aspect of the present invention, the adhesive layer for an optical film described above, the first optical film provided on one side of the adhesive layer, and the adhesive layer provided on the other side of the adhesive layer An optical member is provided having a glass or a second optical film coated thereon. 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 described above may be used by directly coating one side or both sides of the optical film to form a pressure-sensitive adhesive layer. In the present invention, for the reasons described above, it is desirable to form a pressure-sensitive adhesive layer on a separator or the like in advance and transfer this to one side or both sides of the optical film. In addition, before the transfer, the surface of the optical film may be subjected to surface treatment such as formation of an easy-adhesion treatment layer, formation of an antistatic layer, or the like, 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)>
It is preferable that the optical member of the present invention further has at least one easy-adhesion treatment layer between the first optical film and the pressure-sensitive adhesive layer for optical film.

Further, as a more preferable embodiment, the optical member of the present invention includes, between the first optical film and the pressure-sensitive adhesive layer for an optical film, a first easy-adhesion treatment in order from the first optical film side. layer, and 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 more strongly adhered to each other.

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

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. Materials constituting the primer layer include, for example, various polymers, metal oxide sols, silica sols, and the like. 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.

Commercially available products can be used as the oxazoline group-containing polymer. Examples include, but are not limited to, Epocross (registered trademark) series manufactured by Nippon Shokubai Co., Ltd. (for example, Epocross (registered trademark) WS700). In addition, regarding 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 of forming the primer layer is not particularly limited, and the primer layer can be formed by applying a raw material (undercoat) for the primer layer using a coating method such as a coating method, a dipping method, or a spray method, and drying. can.

<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. Examples include, but are not limited to, compensation films, brightness enhancement films for enhancing display contrast, and laminates thereof. Preferably, the optical film (first optical film or second optical film) is a polarizing plate. The polarizing plate will be described below.

〔Polarizer〕
In the present invention, a polarizing plate suitable as an optical film is obtained by pasting together a protective film and a polarizer using an adhesive by a conventionally known method. After that, it can be produced by heating and drying or curing with ultraviolet rays, electron beams, or the like. 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 iodine and/or potassium iodide with a concentration of 0.1% by mass or more and 10% by mass or less 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 also commercially available.

The thickness of the polarizer is not particularly limited, but is generally 3 μm or more and 80 μm or less, preferably 10 μm or more and 25 μm or less. When the thickness of the polarizer is 25 μm or less, the protective film can contribute to the ability to suppress shrinkage of the polarizer in the single-sided protective polarizing plate. As a result, shrinkage due to heating or the like can be suppressed, and the generation of air bubbles at the edges and peeling or floating of the polarizing plate can be further suppressed.

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. Among them, a polarizing plate whose one side is protected as an optical film (single-sided protected polarizing plate) is more preferable. 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. On the other side of the polarizer, a transparent protective film is adhered with an adhesive or a protective layer is formed. The protective layer can be formed using thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, and silicone or ultraviolet curable resins.

The thickness of the polarizing plate is not particularly limited, and is generally 20 μm or more and 200 μm or less, but from the viewpoint of thinning, it is preferably 100 μm or less. Such a thin polarizing plate is preferable from the viewpoint of exhibiting the effects of the pressure-sensitive adhesive 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 the polyvinyl alcohol adhesive, and preferably 0.2 μm or more and 10 μm or less for the ultraviolet curing adhesive. This is because when the thickness of the adhesive layer is within the above range, a uniform in-plane thickness can be obtained and sufficient adhesive strength can be obtained.

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. Moreover, from the viewpoint of exhibiting the effects of the pressure-sensitive adhesive for optical films 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 were measured under conditions of 23° C. and a relative humidity of 55% RH.

(Measurement of weight average molecular weight (Mw) of (meth)acrylic acid ester copolymer (A1))
The weight average molecular weight of each (meth)acrylic acid ester copolymer (A1) 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.

(Preparation of single-sided protective polarizing plate)
A polyvinyl alcohol film having a thickness of 45 μm was stretched up to 3 times while being dyed in an iodine solution having a concentration of 0.3% by mass at 30° C. for 1 minute between rolls having different speed ratios. Thereafter, the film stretched to 3 times was immersed in an aqueous solution containing 4% by mass boric acid and 10% by mass potassium iodide at 60° C. for 0.5 minutes until the total stretching ratio reached 6 times. Stretched. Then, the film stretched up to 6 times was washed by being immersed for 10 seconds in an aqueous solution containing 1.5% by mass of potassium iodide at 30°C. After that, drying was performed at 50° C. for 4 minutes to obtain a polarizer. On one side of the polarizer, an 80 μm thick uniaxially stretched PET film (Cosmo Shine (registered trademark) super birefringence type (SRF) PET film manufactured by Toyobo Co., Ltd.) is laminated with a polyvinyl alcohol-based adhesive. A thin polarizing plate with single-side protection (also referred to simply as a single-side protection polarizing plate) having a thickness of 98 μm was produced.

[Production Example 1: Preparation of solution of (meth)acrylate copolymer (A1)]
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with the following copolymer raw materials and the like. That is, n-butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) 50 parts by mass, 2-ethylhexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 49 parts by mass, 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 1 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 122.2 parts by mass of ethyl acetate. After that, nitrogen gas was introduced while gently stirring. After purging with nitrogen gas, the temperature of the liquid in the flask was kept around 55° C., and the polymerization reaction was carried out for 4 hours. Thus, a solution of (meth)acrylate copolymer (A1) having a weight average molecular weight (Mw) of 1,250,000 was prepared.

[Production Example 2: Preparation of solution of (meth)acrylate copolymer (A2)]
In Production Example 1, the same operation as in Production Example 1 was performed, except that the types and composition ratios of the respective monomers forming the (meth)acrylic acid ester copolymer were changed as shown in Table 1 below. Thus, a solution of (meth)acrylate copolymer (A2) having a weight average molecular weight (Mw) of 1,300,000 was prepared.

[Production Example 3: Preparation of solution of (meth)acrylate copolymer (A3)]
In Production Example 1, the same operation as in Production Example 1 was performed, except that the types and composition ratios of the respective monomers forming the (meth)acrylic acid ester copolymer were changed as shown in Table 1 below. Thus, a solution of (meth)acrylate copolymer (A3) having a weight average molecular weight (Mw) of 1,250,000 was prepared. Table 1 also shows the glass transition temperatures (Tg) and weight average molecular weights (Mw) of the (meth)acrylate copolymers (A1) to (A3). A blank in Table 1 indicates that the monomer was not used.

[Synthesis Example 1: Compound Represented by General Formula 1a: Method for Synthesizing Silane Coupling Agent (B)]
The inside of a four-necked flask equipped with a stirrer, a thermometer and a condenser tube was purged with nitrogen, and raw materials for the compound represented by the following general formula 1a were charged. That is, 336.40 g (2 mol) of hexamethylene diisocyanate (HDI, molecular weight = 168.20) and 205.28 g of 3-isocyanatopropyltriethoxysilane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight = 205.28). (1 mol) was charged. Thereafter, 0.1 g of tetramethylammonium capriate was added as an isocyanurate catalyst while stirring at 70°C. When the refractive index of the reaction solution was measured and the conversion rate reached 25%, 0.2 g of phosphoric acid was added to stop the isocyanurate reaction. Furthermore, the resulting isocyanurate-type polyisocyanate composition was heated at 100° C. for 150 minutes. Here, for the refractive index measurement of the reaction liquid, the refractive index n ₂₀ ^D was measured with an Abbe refractometer. A conversion rate was calculated from the obtained refractive index.

Subsequently, the isocyanurate-type polyisocyanate composition obtained above was filtered. Thereafter, unreacted HDI monomer and a portion of 3-isocyanatopropyltriethoxysilane were removed by first thin film distillation under conditions of 160° C. and 0.8 mmHg. The total content of HDI monomer and 3-isocyanatopropyltriethoxysilane in the triethoxysilyl group-containing isocyanurate-type polyisocyanate composition after the first thin-film distillation was 12.0% by mass. The isocyanurate-type polyisocyanate composition after the first thin film distillation was heat-treated at a temperature of 120° C. for 60 minutes. Excess HDI monomer was then removed by a second thin film distillation under conditions of 160° C. and 0.1 mmHg. The content of the HDI monomer in the isocyanurate-type polyisocyanate composition after the second thin film distillation was 0.10% by mass. The isocyanurate-type polyisocyanate composition after the second thin film distillation was heat-treated at a temperature of 90° C. for 180 minutes. As a result, a triethoxysilyl group-containing isocyanurate-type polyisocyanate was obtained as the silane coupling agent (B). The resulting triethoxysilyl group-containing isocyanurate-type polyisocyanate is a compound having a structure represented by general formula 1a.

In the following examples, when using the compound represented by the same general formula 1a as in Synthesis Example 1 as the silane coupling agent (B), commercially available X-12-1159L (compound represented by general formula 1a (manufactured by Shin-Etsu Chemical Co., Ltd.).

[Synthesis Example 2: Compound Represented by Formula 2a: Method for Synthesizing Silane Coupling Agent (B)]
Synthesis Example 1 was repeated except that 504.60 g (3 mol) of HDI and 205.28 g (1 mol) of 3-isocyanatopropyltriethoxysilane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd.) were charged. Thus, a triethoxysilyl group-containing isocyanurate polyisocyanate of the compound represented by the general formula 2a was obtained as the silane coupling agent (B).

[Synthesis Example 3: Compound Represented by Formula 3a: Method for Synthesizing Silane Coupling Agent (B)]
Synthesis Example 1 was repeated except that 336.40 g (2 mol) of HDI and 410.56 g (2 mol) of 3-isocyanatopropyltriethoxysilane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd.) were charged. Thus, a triethoxysilyl group-containing isocyanurate polyisocyanate of the compound represented by the general formula 3a was obtained as the silane coupling agent (B).

[Synthesis Example 4: Compound Represented by Formula 4a: Method for Synthesizing Silane Coupling Agent (B)]
Same as Synthesis Example 1, except that 504.60 g (3 mol) of HDI and 410.56 g (2 mol) of 3-isocyanatopropyltriethoxysilane (KBE-9007, manufactured by Shin-Etsu Chemical Co., Ltd.) were charged as amounts to be charged. Then, a triethoxysilyl group-containing isocyanurate-type polyisocyanate of the compound represented by the general formula 4a was obtained as the silane coupling agent (B).

<Example 1>
[Preparation of adhesive for optical film]
With respect to 100 parts by mass of the solid content of the (meth)acrylic acid ester copolymer (A1) solution obtained in Production Example 1 (that is, 100 parts by mass of the (meth)acrylic acid ester copolymer (A1)), isocyanate 0.2 parts by mass of X-12-1159L (containing 90% by mass of the compound represented by general formula 1a, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (B) having a plurality of groups is blended to form an optical film. A pressure-sensitive adhesive (solid content: 18% by mass) was prepared.

[Formation of adhesive layer]
The optical film pressure-sensitive adhesive obtained above was applied to one side of a 38 μm-thick polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, MRF38, without oligomer prevention layer) that had been subjected to silicone treatment. A layer thickness of 25 μm was applied. Next, the pressure-sensitive adhesive applied to the film was heat-treated at 110° C. for 4 minutes to form the pressure-sensitive adhesive layer of Example 1. The heat treatment was performed by a float drying method in which hot air was directly blown from above and below the film.

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

<Examples 2 to 18 and Comparative Examples 1 to 8>
As shown in Table 2 below, the (meth)acrylic acid ester copolymer (A) constituting the pressure-sensitive adhesive for optical films, and the silane coupling agent (B) having multiple isocyanate groups (Silane cup (Including examples using those that do not correspond to the ring agent (B)), the crosslinking agent / curing agent component (C), the silane coupling agent (D) that does not contain an isocyanate group (Silane coupling agent (B) Examples 2 to 18 and Examples 2 to 18 and An optical member (single-sided protective polarizing plate with an adhesive layer) corresponding to Comparative Examples 1 to 8 was produced.

In Table 2 above,
1. The amount of components (B), (C) and (D) added (unit: parts by mass) represents the amount added based on 100 parts by mass of the copolymer (A).

2. "-" in the table indicates that such component is not blended.

3. "D-110N" is a product manufactured by Mitsui Chemicals, Inc. (Takenate (registered trademark) D-110N, 75% by weight ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate, number of isocyanate groups in one molecule: 3 ).

4. “KBM-403” is a product of Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltrimethoxysilane).

5. "KBE-9007": A product of Shin-Etsu Chemical Co., Ltd. (3-isocyanatopropyltriethoxysilane).

6. “X-12-1159L” is a product manufactured by Shin-Etsu Chemical Co., Ltd. (compound represented by general formula 1a; silane coupling agent containing an isocyanurate skeleton having multiple isocyanate groups).

7. “Formula (7) of Document 1, paragraph “0063”” is a silane coupling agent having an isocyanate group represented by Formula (7) shown in Patent Document 1, paragraph “0063”.

[evaluation]
The optical film pressure-sensitive adhesives prepared in Examples 1 to 18 and Comparative Examples 1 to 8, and the pressure-sensitive adhesive layer-attached single-sided protective polarizing plate (sample), which is an optical member, were subjected to the following conditions. made an evaluation.

<End bubbles>
The optical members (single-sided protective polarizing plate with pressure-sensitive adhesive layer) produced in Examples 1 to 18 and Comparative Examples 1 to 8 were cut into 37 inch size samples. The cut sample was adhered to non-alkali glass (manufactured by Corning, Eagle XG) having a thickness of 0.7 mm using a laminator. Then, the sample was autoclaved at 50° C. and 0.5 MPa for 15 minutes to completely adhere the sample to the non-alkali glass. The samples subjected to such treatment were subjected to the following durability tests (1) and (3), respectively, and after each test, the appearance between the polarizing plate (the polarizer surface side on which the adhesive layer was formed) and the glass was visually evaluated according to the following criteria. In this evaluation, air bubbles generated within 1 mm of both ends of the polarizing plate in the stretching direction were observed.

-Visual evaluation-
◎: No bubbles newly generated at the edge ○: Slight foaming at the edge, but no practical problem None x: A significant number of air bubbles are present at the edge, which poses a practical problem.

<Durability>
The samples treated in the same manner as the end bubbles were subjected to the following durability tests (1) to (3), respectively, and after each test, the polarizing plate (polarizer surface side on which the adhesive layer was formed) and the glass The appearance during the period was visually evaluated according to the following criteria. In this evaluation, the entire polarizing plate was visually observed.

(1) Treated at 85°C for 500 hours (heating test)
(2) Treated for 500 hours in an atmosphere of 60°C and 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 floating ○: Slight peeling or foaming at the edge, but no practical problem △: Peeling or foaming at the edge, but special Practically no problem unless it is used for such a purpose. x: Remarkable peeling at the edge, presenting a problem in practical use.

<Reworkability>
The optical members prepared in Examples 1 to 18 and Comparative Examples 1 to 8 were cut into a size of 25 mm in width and 100 mm in length, and Sample 2 was cut into a size of 420 mm in length and 320 mm in width. (three sheets produced). Each of Sample 1 and Sample 2 was attached to a non-alkali glass plate (manufactured by Corning, Eagle XG) with a thickness of 0.7 mm using a laminator, and then autoclaved at 50 ° C. and 506.5 kPa (5 atm) for 15 minutes. Treated and completely adhered (initial stage). After that, heat treatment was performed for 48 hours under dry conditions at 50°C (after heating).

The initial and post-heating adhesive strengths of Sample 1 were 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).

Further, with respect to the sample 2 (three pieces), the sample was manually peeled off from the alkali-free glass plate, and 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 ○: Some of the 3 sheets were ruptured, but could be peeled off by peeling again Can be peeled off by peeling ×: Adhesive residue was generated on all three sheets, or the film was broken and could not be peeled off no matter how many times it was peeled off.

Each evaluation result is shown in Table 3 below.

As is clear from Table 3 above, the pressure-sensitive adhesive layer-attached single-sided protective polarizing plates produced using the pressure-sensitive adhesives for optical films of the present invention in Examples 1 to 18 were able to withstand harsh environments (high temperature, (high humidity, heat shock) (especially suppression of bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) can be improved, and reworkability (processability) is also excellent. I understand.

On the other hand, the adhesive layer-attached single-sided protective polarizing plates of Comparative Examples 1 to 8 all had a significant number of air bubbles at the edge in the evaluation of air bubbles at the edge after the heat shock (HS) test. It turned out that there was a problem. In addition, either durability (suppression of air bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) or reworkability (processability) is poor (x evaluation) or low ( △ evaluation) It turned out that there was something.

Claims (19)

An optical film pressure-sensitive adhesive comprising a polymer component (A) having a hydroxyl group and a silane coupling agent (B) having a plurality of isocyanate groups,
The silane coupling agent (B) contains at least one compound selected from the group consisting of compounds represented by the following general formulas 2 to 4 containing an isocyanurate skeleton. Film adhesive :

In the general formula 2,
R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁶ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n is an integer of 1 or more and 8 or less,
a is an integer of 0 or more and 3 or less,

In the general formula 3,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ and R ⁵ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ is an alkylene group having 1 to 16 carbon atoms,
Y ¹ and Y ² are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less,

In the general formula 4,
R ¹ , R ² , R ⁷ and R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms,
R ³ , R ⁵ and R ⁹ are each independently an alkylene group having 1 to 8 carbon atoms,
R ⁴ and R ¹⁰ are each independently an alkylene group having 1 to 16 carbon atoms,
Y ¹ , Y ² and Y ³ are groups represented by the following formula 5,
n and m are each independently an integer of 1 or more and 8 or less,
a and b are each independently an integer of 0 or more and 3 or less,

In Formula 5, * means a portion connected to another atom (adjacent atom). 2. The silane coupling agent according to claim 1, wherein the silane coupling agent (B) contains at least one compound selected from the group consisting of compounds represented by the following general formulas 2a to 4a: Adhesive for optical films .

3. The pressure-sensitive adhesive for optical films according to claim 1, wherein the polymer component (A) having a hydroxyl group is a (meth)acrylate copolymer (A1). 4. The composition according to any one of claims 1 to 3, further comprising at least one component (C) selected from a cross-linking agent and a curing agent capable of reacting with the polymer component (A) having hydroxyl groups. adhesive for optical films. 5. The pressure-sensitive adhesive for optical films according to any one of claims 1 to 4, further comprising a silane coupling agent (D) containing no isocyanate group. The (meth)acrylic acid ester copolymer (A1) is
(a1) a structural unit derived from an alkyl (meth)acrylate monomer, and (a2) a structural unit derived from a (meth)acrylate monomer having a hydroxyl group and (a3) a structural unit derived from a monomer having a carboxyl group. at least one structural unit that
The pressure-sensitive adhesive for optical films according to any one of claims 3 to 5, comprising The pressure-sensitive adhesive for optical films according to any one of claims 3 to 6, wherein the (meth)acrylate copolymer (A1) has a weight average molecular weight of 500,000 or more and 2,000,000 or less. . 7. The pressure-sensitive adhesive for optical films according to claim 6, wherein the alkyl in the component (a1) has from 1 to 18 carbon atoms. At least one component (C) selected from the crosslinking agent and the curing agent is contained in an amount of 0.001 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer component (A) having a hydroxyl group. The pressure-sensitive adhesive for optical films according to any one of claims 4 to 8. At least one component (C) selected from the cross-linking agent and curing agent is at least one selected from the group consisting of isocyanate compounds, carbodiimide compounds, oxazoline compounds, epoxy compounds, polyfunctional acrylate monomers and peroxides. 10. The pressure-sensitive adhesive for optical films according to any one of claims 4 to 9, which contains seeds. 0.001 parts by mass or more and 5 parts by mass or less of the silane coupling agent (D) containing no isocyanate group is contained with respect to 100 parts by mass of the polymer component (A) having a hydroxyl group. 11. The adhesive for optical films according to any one of 5 to 10. An optical film pressure-sensitive adhesive layer formed from the optical film pressure-sensitive adhesive according to any one of claims 1 to 11. The pressure-sensitive adhesive layer for an optical film according to claim 12;
and a first optical film provided on one surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer for an optical film according to claim 12;
a first optical film provided on one surface of the pressure-sensitive adhesive layer;
and a glass or a second optical film provided on the other surface of the pressure-sensitive adhesive layer. 15. The optical member according to claim 13, further comprising at least one easy-adhesion treatment layer between the first optical film and the pressure-sensitive adhesive layer for optical film. Between the first optical film and the pressure-sensitive adhesive layer for an optical film, a first easy-adhesion treatment layer and a second easy-adhesion treatment layer are provided in order from the first optical film side. The optical member according to claim 15 . An image display device using at least one optical member according to any one of claims 13 to 16. 12. The pressure-sensitive adhesive layer for an optical film, comprising: applying the pressure-sensitive adhesive for an optical film according to any one of claims 1 to 11 onto a release sheet, and then heat-treating the pressure-sensitive adhesive for a cross-linking reaction. manufacturing method. 19. The method for producing an optical film pressure-sensitive adhesive layer according to claim 18, wherein the temperature of the heat treatment is 80[deg.] C. or higher and 120[deg.] C. or lower.