KR20200067731A - Adhesive for optical film, adhesive layer, optical member and display apparatus - Google Patents

Abstract

Provided is an adhesive for an optical film, capable of improving durability and suppressing bending and dent damages under harsh environments (high temperature, high humidity, thermal shock) even when the adhesive is used for a single-sided protective polarizing plate, and achieving excellent rework properties (processability). The adhesive for the optical film includes: a polymer component (A) having a hydroxyl group; and a silane coupling agent (B) having a plurality of isocyanate groups, wherein the silane coupling agent (B) is a compound having an isocyanurate skeleton including a plurality of isocyanate groups having a specific structure.

Description

Adhesive for optical film, adhesive layer, optical member and image display device {ADHESIVE FOR OPTICAL FILM, ADHESIVE LAYER, OPTICAL MEMBER AND DISPLAY APPARATUS}

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

Currently, a display panel in a flat state such as a liquid crystal monitor panel (LCD) and a flat panel display panel (PDP) is mainly used as the display panel. A laminate in which a plurality of films are laminated is usually attached to the surface of a flat display panel and joined. For example, in the LCD, an optical film such as a polarizing plate, a retardation plate, an enlarged viewing angle, and a brightness improving film is usually laminated on the surface of a liquid crystal panel. In addition, each layer constituting the flat display panel may be pasted and bonded by an adhesive layer formed of various adhesives.

As a necessary characteristic of the pressure-sensitive adhesive, durability in the adhesive state of the pressure-sensitive adhesive that does not cause defects such as peeling or lifting due to the pressure-sensitive adhesive is required for an endurance test by heating, humidification, and the like, which is usually performed as an environmental acceleration test.

Meanwhile, a cheaper and thinner polarizing plate has been recently demanded. As one form, for a double-sided protective polarizing plate in which both sides of a conventional polarizer are bonded to each other with a protective film, a single-sided protective polarizing plate using only one protective film on one side of the polarizer has been proposed. However, it is known that, unlike the conventional double-sided protective polarizing plate, this single-sided protective polarizing plate shrinks significantly during durability, particularly in heat durability or heat shock cycle tests.

For this reason, in such a single-sided protective polarizing plate, since the same durability as that of a conventional double-sided protective polarizing plate is required, in addition to suppressing the occurrence of peeling or lifting, the polarizing plate shrinks significantly during the durability test, and thus occurs at the edge portion (end) of the polarizing plate. It is required to suppress the air bubbles to be said. In order to suppress the bubbles generated at the edge of the polarizing plate, it is considered effective to use a silane coupling agent having a plurality of isocyanate groups that can function as a crosslinking agent and improve wettability in glass.

As the pressure-sensitive adhesive containing a silane coupling agent having an isocyanate group, an pressure-sensitive adhesive containing at least one component (C) selected from the pressure-sensitive adhesive component (A), the silane coupling agent (B) having an isocyanate group, and a crosslinking agent and curing agent has been proposed (eg For example, see Patent Document 1).

Further, as another invention, a reaction product of a polymer [P] having at least one of a carboxyl group or a hydroxyl group and having a glass transition temperature of -80°C or more and 10°C or less, a silane compound (f2) having an isocyanate group and an alkoxysilyl group, and a polyol (f1) (F) is a pressure-sensitive adhesive comprising a reaction product (F) containing a hydroxyl group and an alkoxysilyl group and a reactive compound (G) obtained by reacting at least one of a carboxyl group or a hydroxyl group in the polymer [P]. Has been proposed (for example, see Patent Document 2).

[Advanced technical literature]

[Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2013-209600

[Patent Document 2] Japanese Patent Application Publication No. 2009-280776

However, according to the examination of the inventor, it was found that the following problems exist. In patent document 1, when the silane coupling agent which has an isocyanate group does not have one isocyanate group or an isocyanurate skeleton, it is impossible to improve the wettability in glass and to function as a crosslinking agent. In addition, when there are a plurality of isocyanate groups, the crosslinking density is too high when used as a crosslinking agent. For this reason, it has been found that in either case, there is a problem that air bubbles generated in the edge portion of the polarizing plate during the durability test cannot be suppressed. Moreover, it has been found that there is a problem that the reworkability (processability) is not sufficient.

In addition, in patent document 2, the silane coupling agent which has an isocyanate group has one isocyanate group. When the isocyanate group is one, it is not possible to improve the wettability in glass and to function as a crosslinking agent. For this reason, it has been found that there is a problem in that both occurrence of excitation during the durability test and bubbles generated at the edge of the polarizing plate cannot be suppressed. Moreover, it has been found that there is a problem that the reworkability (processability) is not sufficient.

The present invention has been made in light of the above circumstances. In other words, even when used in a single-sided protective polarizing plate, durability under harsh environments (high temperature, high humidity, and heat shock) (especially suppression of peeling and lifting of the polarizing plate and suppression of bubbles generated at the edge of the polarizing plate) It is an object to provide a pressure-sensitive adhesive for an optical film that can be improved and further excellent in reworkability (processability).

The present inventor has made extensive studies to solve the above problems. As a result, it has been found that the above problems can be solved by an adhesive comprising a silane coupling agent having a plurality of isocyanate groups having a specific structure, and the present invention has been completed.

In other words, the present invention is a pressure-sensitive adhesive for an optical film comprising a polymer component (A) having a hydroxyl group and a silane coupling agent (B) having a plurality of isocyanate groups, and the silane coupling agent (B) having a plurality of isocyanate groups is isocyanate It is a pressure-sensitive adhesive for an optical film comprising at least one compound selected from the group consisting of compounds represented by the following general formula 1 to general formula 4 having an anurate skeleton.

(Formula 1)

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.

(Formula 2)

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 , Y ² 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.

(Formula 3)

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 , Y ² is a group represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 4)

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 , Y ³ are groups represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 5)

In Equation 5, * denotes a part connected to another atom (adjacent atom).

According to the present invention, even when used for a single-sided protective polarizing plate, it is possible to improve the durability (especially suppression of bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) under harsh environments (high temperature, high humidity, and thermal shock). There is further provided an adhesive for an optical film that has excellent reworkability (processability).

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

[Adhesive for optical film]

The adhesive for optical films of the present invention is an adhesive for optical films comprising 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 is characterized by comprising at least one compound selected from the group consisting of compounds represented by the following general formula 1 to general formula 4 having an isocyanurate skeleton will be.

(Formula 1)

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.

(Formula 2)

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 , Y ² 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.

(Formula 3)

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 , Y ² is a group represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 4)

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 , Y ³ are groups represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 5)

In Equation 5, * denotes a part connected to another atom (adjacent atom).

According to the pressure-sensitive adhesive for an optical film of the present invention having such a configuration, even when used in a single-sided protective polarizing plate, durability in harsh environments (high temperature, high humidity, heat shock) (especially, suppression of air bubbles generated at the edge of the polarizing plate and polarizing plate) Suppression of peeling), and further excellent in reworkability (processability).

Recently, a cheaper and thinner polarizing plate is required. As one form, a single-sided 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 suppression force of shrinkage of the polarizer by the protective film becomes small. For this reason, the inventors have found that a problem that shrinkage due to heating or the like is likely to occur and bubbles are particularly likely to occur at the edge of the polarizing plate. There, the inventor has made extensive studies to solve these problems. As a result, it has been found that the above problem can be solved by using an adhesive comprising a polymer component (A) having a hydroxyl group and a silane coupling agent (B) having a plurality of isocyanate groups (NCO) having a specific structure. By using a silane coupling agent (B) having a plurality of isocyanate groups having a specific structure, wettability in glass and a crosslinking effect by a plurality of NCOs are simultaneously realized. Moreover, it has an NCO cross-linked structure and at the same time can secure flexibility. For this reason, the crosslinking effect is large, and at the same time, the stress relaxation property is not impaired, and in the single-sided protective polarizing plate, the suppression force of the shrinkage of the polarizer by the protective film is small, so that the shrinkage due to heating can be suppressed. As a result, it is possible to suppress the generation of bubbles at the edge portion and suppress peeling and lifting of the polarizing plate. In other words, durability in a harsh environment (high temperature, high humidity, thermal shock) (especially at the edge of the polarizer) by using an adhesive comprising a copolymer component (A) having a hydroxyl group and the silane coupling agent (B) It was found that it is possible to improve the suppression of generated bubbles and suppression of peeling of the polarizing plate), and furthermore, an adhesive excellent in reworkability (processability) can be obtained.

Meanwhile, the mechanism is speculative, and the present invention is not limited to the mechanism.

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

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

<Polymer component having hydroxyl group (A)>

The pressure-sensitive adhesive for an optical film 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 homopolymer such as an unsaturated compound containing a hydroxyl group or an unsaturated compound containing a polar group capable of introducing or generating a hydroxyl group by any chemical modification after polymerization, a copolymer with another polymerizable monomer, And at least one (co)polymer selected from the group consisting of graft polymers for other polymers, and as a result, the hydroxyl groups are irregularly or regularly pendant to the molecular chains, which are structurally branched or linear, or hydroxyl groups. Refers to the first half from the oligomer to the polymer having a structure in which the side chain chain having a graft.

The polymer component (A) can be produced by a known method. For example, a polymerization method of an unsaturated compound containing a hydroxyl group, a method of copolymerizing an unsaturated compound containing a hydroxyl group with another polymerizable monomer, a method of grafting a hydroxyl group-containing unsaturated compound to a polymer, a diol compound as a polar group in the polymer, a polyol compound, an epoxy-containing compound Or a method of reacting a compound having at least one hydroxyl group with a bifunctional or higher function, and a method of generating a hydroxyl group by a chemical reaction such as oxidation or hydrolysis of a polar group in a polymer. The polymer produced from the above production method and the like, among them, (meth)acrylic acid ester copolymer (A1), as shown below, is preferred. Hereinafter, a preferable copolymer (A1) is explained in full detail.

<(meth)acrylic acid ester copolymer (A1)>

It is preferable that the copolymer component (A) having the hydroxyl group is a (meth)acrylic acid ester copolymer (A1).

The weight average molecular weight (Mw) of the copolymer (A1) by gel permeation chromatography (GPC) is preferably 500,000 or more and 2 million or less. The following effects can be obtained by crosslinking the high molecular weight copolymer (A1) in the above range with a silane coupling agent (B) having a plurality of isocyanate groups having a specific structure. In other words, the crosslinking effect is large and at the same time there is no damage to the stress relaxation properties. For this reason, in the single-sided protective polarizing plate, the suppression force of shrinkage of the polarizer by the protective film becomes small, so that shrinkage due to heating or the like can be suppressed. As a result, it is possible to obtain a significant improvement in durability under harsh environments, such as suppressing the generation of bubbles at the edge portion and suppressing peeling and lifting of the polarizing plate. When the weight average molecular weight (Mw) is 500,000 or more, it is preferable in that it can prevent the durability at high temperature and the rework property after heating from falling. On the other hand, if it is 2 million or less, it is preferable in that there are few gel components in the polymer solution and there is no deterioration of the coating property due to an increase in the viscosity of the coating solution during coating.

The weight average molecular weight (Mw) of the copolymer (A1) by GPC is more preferably from 900,000 to 1.5 million, and more preferably from 1,000,000 to 1.5,000,000. If the weight average molecular weight (Mg) of the copolymer (A1) is within the above range, durability in harsh environments (high temperature, high humidity, and thermal shock) can be further improved. The weight average molecular weight (Mg) of the copolymer (A1) can be easily controlled by those skilled in the art. For example, it can be controlled by appropriately adjusting reaction conditions such as the type and/or amount of polymerization initiator used in the polymerization reaction to be described later, reaction temperature, reaction time, and the like.

On the other hand, the weight average molecular weight (Mw) of the copolymer (A1) can be measured by GPC, and can be specifically measured by a method shown in Examples.

As the structural unit constituting the copolymer (A1) in the present invention

(a1) a structural unit derived from an alkyl (meth)acrylate monomer (hereinafter also simply referred to as "component (a1)"), and

(a2) Structural units derived from (meth)acrylate monomers having a hydroxy group (hereinafter also referred to simply as "component (a2)") and (a3) structural units derived from monomers having a carboxyl group (hereinafter, only "component (a3)" (Also referred to as'') at least one structural unit selected from the group consisting of

It is preferred to include. In other words, it is preferable that the copolymer (A1) includes component (a1) and component (a2); It is also preferred to include component (a1) and component (a3); Moreover, it is also preferable to include a component (a1), a component (a2), and a component (a3).

On the other hand, in the present specification, for example, "Copolymer X includes a structural unit derived from monomer Y1 and a structural unit derived from monomer Y2" is a raw material monomer used when obtaining copolymer X by copolymerization with monomer Y1. It is meant to include monomer Y2.

Hereinafter, the structural unit derived from each monomer which can constitute the copolymer (A1) will be described in order.

(Constituent unit derived from (a1)alkyl (meth)acrylate monomer)

It is preferable that the copolymer (A1) contains (a1) alkyl (constituent unit derived from a (meth)acrylate monomer (hereinafter also simply referred to as "component (a1)"), and such component (a1) is (meth) It is considered to have the meaning of securing adhesiveness and securing basic properties by being included as a structural unit of the acrylate copolymer (A1).

In the present invention, the structure of the alkyl (meth)acrylate monomer is not particularly limited as long as the alkyl group is introduced at the ester site of the (meth)acrylate.

Although the number of carbons of the alkyl group concerned is not particularly limited, 1 or more and 18 or less are preferable, 1 or more and 12 or less are more preferable, 1 or more and 10 or less are also preferable, and 1 or more and 8 or less are also more preferable, and 1 or more and 6 or less The following are particularly preferred. If the number of carbons of the alkyl group concerned is within the above range, it is preferable from the viewpoints of versatility, price and handling. Further, 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. On the other hand, when the alkyl group is cyclic, the number of carbon atoms is 3 or more.

Although it does not specifically limit as a related alkyl group, Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, isobutyl group, n-pentyl group, isopentyl group, n- Hexyl group, 2-hexyl group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, t-heptyl group, n- Octyl group, isooctyl group, t-octyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, And an octadecyl group or a cyclohexyl group. In particular, a methyl group, an n-butyl group, an n-hexyl group, a 2-ethylhexyl group, a nonyl group, and an isononyl group are preferable from the viewpoint of securing adhesiveness or securing basic properties.

Accordingly, specific examples of the alkyl (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, Isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate , Heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. Among them, methyl (meth)acrylate and n-butyl (meth)acrylate are preferred from the viewpoint of improving heating durability and adhesion (especially rework property). Meanwhile, the component (a1) may be used alone or in combination of two or more.

In the copolymer (A1), the content of the component (a1) (the amount of the alkyl (meth)acrylate monomer as the raw material monomer) is not particularly limited, but the total of the constituent units constituting the (meth)acrylate copolymer (A1) It is preferable that 64.5 mass% or more and less than 99.5 mass% with respect to 100 mass %, 80 mass% or more and 99 mass% or less are more preferable, 65 mass% or more and 99.4 mass% or less, 75 mass% or more and 99.4 mass% or less, 85 Particularly preferred is mass% or more and 99 mass% or less, and 90 mass% or more and 99 mass% or less. When the content of the component (a1) in the copolymer (A1) is within the above range, it is preferable from the viewpoint of good balance with the content of other raw material monomers, which will be described later, and improvement in durability. In addition, in this specification, "the total amount of 100 mass% of the structural unit which comprises (meth)acrylate copolymer (A1)" is all the raw materials used when obtaining (meth)acrylate copolymer (A) by copolymerization. It means that the total amount of the monomers is 100% by mass.

(Constituent unit derived from (meth)acrylate monomer having (a2)hydroxy group)

It is preferable that the copolymer (A1) contains a structural unit derived from a (meth)acrylate monomer having a (a2)hydroxy group (hereinafter also simply referred to as "component (a2)"). Such component (a2) is rich in reactivity with a silane coupling agent (B) or a crosslinking agent. For this reason, it is considered to have the significance of improving the cohesiveness, heat resistance, and durability of the pressure-sensitive adhesive layer described later by being included as a structural unit of the copolymer (A1). In addition, a portion of component (a2) of copolymer (A1) may react with at least one component (C) selected from a silane coupling agent (B), a crosslinking agent, and a curing agent. For this reason, the crosslinking density of the pressure-sensitive adhesive layer described later becomes high, and the pressure-sensitive adhesive layer becomes hard and the amount of deformation of the pressure-sensitive adhesive layer at the time of re-release is small. As a result, it was found that the adhesive strength is poor, the desired rework property can be obtained, and peeling and lifting can be suppressed even in durability.

In the present invention, the structure of the (meth)acrylate monomer having a hydroxy group is not particularly limited as long as the hydroxy group is introduced in a part of the (meth)acrylate monomer.

Specific examples of the (meth)acrylate monomer having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, and pentaerythritol. Tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, neopentyl glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, 2- Hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, hydroxy Methyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, cyclohexane dimethanol monoacrylate, and the like; and alkylglycidyl ether, arylglycidyl ether, and glycidyl (meth)acrylate. The compound etc. which can be obtained by addition reaction of a glycidyl group containing compound and (meth)acrylic acid etc. are mentioned. Among them, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylamide, and cyclohexanedimethanol monoacrylic from the viewpoint of efficiently functioning as a crosslinking point. The rate is preferable, and 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are more preferable. Meanwhile, these components (a2) may 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 compounding amount of the (meth)acrylate monomer having a hydroxyl group as the raw material monomer) is the total amount of the constituent units constituting the copolymer (A1). It is preferably 0.01 mass% or more and 25 mass% or less, and 0.01 mass% or more and 10 mass% or less with respect to 100 mass%. When the content of the component (a2) is 0.01 mass% or more, the crosslinking reaction point is not too small, and it is preferable from the viewpoint of improving durability. On the other hand, when the content of the component (a2) is 10% by mass or less, the proportion of the polar monomers to be blended does not increase relatively, and the polarity of the formed pressure-sensitive adhesive layer is not too high, and it is preferable from the viewpoint of improving durability. The content of the component (a2) is more preferably 0.1 mass% or more and 5 mass% or less, more preferably 0.3 mass% or more and 5 mass% or less, and even more preferably 0.5 mass% or more and 5 mass% or less.

(Constituent unit derived from monomer having a (a3) carboxyl group)

In the present invention, it is preferable that the copolymer (A1) contains a structural unit derived from a monomer having a (a3) carboxyl group (hereinafter also simply referred to as "component (a3)"). Such a component (a3) can mainly contribute to improvement of durability and rework property in the adhesive for optical films.

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

Specific examples of the monomer having a carboxyl group include (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, itaconic anhydride, myristic oleic acid, palmitoleic acid, and oleic acid. Among them, (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, itaconic anhydride are preferred from the viewpoint of good copolymerization with other (meth)acrylic monomers, and (meth)acrylic acid It is more preferable. Meanwhile, these components (a3) may be used alone or in combination of two or more.

When the copolymer (A1) contains the component (a3), the content of the component (a3) (a blending amount of a monomer having a carboxyl group as a raw monomer) is based on 100% by mass of the total amount of constituent units constituting the copolymer (A) , It is preferable that it is 0.01 mass% or more and 7 mass% or less. When the content of the component (a3) is 0.01 mass% or more, the crosslinking reaction point is not too small, and it is preferable from the viewpoint of improving durability. On the other hand, if the content of the component (a3) is 7% by mass or less, the proportion of the polar monomers to be blended does not increase too much, and the polarity of the formed pressure-sensitive adhesive layer is not too high, and it is preferable in terms of improving durability. The content of the component (a3) is more preferably 0.2% by mass or more and 5% by mass or less, and more preferably 0.6% by mass or more and 5% by mass or less.

((A4): Component unit derived from monomers other than (a3) from component (a1)]

The copolymer (A) according to the present invention is a component other than the components (a1) to (a3) which are copolymerizable with the components (a1) to (a3) described above (optionally referred to as "component (a4)") Also referred to as ”) can include derived structural units.

As the component (a4), a known substance can be used as long as the effects of the present invention are not impaired. For example, as a component (a4), the structural unit derived from the (meth)acrylate monomer which has an aromatic ring can be used. 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 (meth)acrylate group in the structure. Although there is no restriction|limiting in particular as an aromatic ring here, A benzene ring, a naphthalene ring, a biphenyl ring, etc. are mentioned.

Specific examples of the (meth)acrylate monomer having an aromatic ring include benzyl (meth)acrylate, phenyl (meth)acrylate, o-phenylphenol (meth)acrylate, phenoxy (meth)acrylate, and pt-butylphenyl ( Meta)acrylate, 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-3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, cresyl ( Having a benzene ring such as meth)acrylate and polystyryl (meth)acrylate; Hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate, etc. Having a naphthalene ring; And those having a biphenyl ring such as biphenyl (meth)acrylate. Among them, benzyl (meth)acrylate and phenoxyethyl (meth)acrylate are preferred from the viewpoint of suppressing light leakage and at the same time making it easy to secure durability. On the other hand, these components (a4) may be used alone or in combination of two or more.

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

Examples of the raw material monomer of the component (a4) include, for example, an acrylic monomer having an epoxy group such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; (Meth)acrylic having amino groups such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, Nt-butylaminoethyl (meth)acrylate, and (meth)acryloyloxyethyltrimethylammonium chloride Monomer; (Meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-methylol (meth)acrylamide, N -(Meth)acrylic monomers having amide groups such as methoxymethyl (meth)acrylamide, N, N-methylenebis (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, and diacetone (meth)acrylamide; 2-methacryloyloxyethyldiphenylphosphate (meth)acrylate, trimethacryloyloxyethylphosphate (meth)acrylate, triacryloyloxyethylphosphate (meth)acrylate, etc. ) Acrylic monomers; (Meth)acrylic monomers having sulfonic acid groups such as sodium sulfopropyl (meth)acrylate, sodium 2-sulfoethyl (meth)acrylate, and sodium 2-acrylamido-2-methylpropanesulfonate; (Meth)acrylic monomers having urethane groups such as urethane (meth)acrylate; 2-acetoacetoxyethyl (meth)acrylate, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris (β-methoxyethyl) silane, vinyl triacetylsilane, methacryloyloxypropyl trimethoxysilane Vinyl monomers having silane groups such as; Styrene, chlorostyrene, α-methylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, vinylpyridine, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclo Fentanyl (meth)acrylate, (meth)acryloylmorpholine, 2-(meth)acrylooxyethylphthalic acid, tetrahydrofurfuryl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ( And meta)acryloyl morpholine.

In addition, a (meth)acrylate monomer having an alkoxyalkyl group or an alkylene oxide group as the raw material monomer of component (a4) can be preferably applied.

Examples of the (meth)acrylate monomer having an alkoxyalkyl group or an alkylene oxide group include, for example, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl ( Meth)acrylate, butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate; Ethoxy-diethylene glycol (meth)acrylate, ethoxy-triethylene glycol (meth)acrylate, methoxy-triethylene glycol (meth)acrylate, methoxy-diethylene glycol (meth)acrylate, propoxy -Diethylene glycol (meth)acrylate, methoxy-triethylene glycol (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate (2-ethylhexyloxy-diethylene glycol (meth)acrylate ), methoxy-polyethylene glycol (meth)acrylate (n=4-10), methoxydipropylene glycol (meth)acrylate, 2-ethylhexyl-diglycol acrylate, and the like.

Meanwhile, the aforementioned monomers may be used alone or in combination of two or more. Moreover, it is preferable that the raw material monomer of component (a4) does not contain olefinic monomers, such as ethylene and propylene. This is because 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, can be easily controlled when producing the (meth)acrylate copolymer (A1). Moreover, it is because molecular weight is difficult to increase.

The content of the structural unit derived from the component (a4) in the copolymer (A1) is 0.01 parts by mass or more and 30 to 100 parts by mass based on 100 parts by mass of the constituent units derived from the component (a1), the component (a2), and the component (a3). It is preferable that it is a mass part or less, and it is more preferable that it is 0.1 mass part or more and 25 mass parts or less.

In one embodiment, in the copolymer (A1), component (a1) is 75 mass% to 99.4 mass%, component (a2) is 0.6 mass% to 25 mass%, preferably component (a1) is 90 mass% to 99% by mass, component (a2) may be included in 1% by mass to 10% by mass.

In another embodiment, in the copolymer (A1), component (a1) is 85 mass% to 99.4 mass%, component (a2) is 0.01 mass% to 10 mass%, component (a3) is 0.01 mass% to 7 mass% , Preferably, the component (a1) may be included in an amount of 90 mass% to 99 mass%, the component (a2) 0.1 mass% to 5 mass%, and the component (a3) 0.2 mass% to 5 mass%.

In another embodiment, in the copolymer (A1), the component (a1) is 65 mass% to 99.4 mass%, the component (a2) is 0.01 mass% to 10 mass%, and the component (a4) is 0.01 mass% to 30 mass% %, preferably 65 mass% to 85 mass% of component (a1), 0.01 mass% to 10 mass% of component (a2), and 5 mass% to 30 mass% of component (a4).

(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, and solution polymerization method using a polymerization initiator, bulk polymerization method, emulsion polymerization method, suspension polymerization method, reverse phase suspension polymerization method, thin film polymerization method, spraying Conventionally known methods, such as a polymerization method, can be used. Examples of the polymerization control method include an adiabatic polymerization method, a temperature-controlled polymerization method, and an isothermal polymerization method. The polymerization initiator may be either a thermal polymerization initiator or a photopolymerization initiator. Further, in addition to or in addition to a method for initiating polymerization with a polymerization initiator, a method for initiating polymerization by irradiation with active energy rays such as radiation, electron beams, or ultraviolet rays may also be employed. Among them, a solution polymerization method using a thermal polymerization initiator or a bulk polymerization method using a photo polymerization 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 serving as a raw material for the copolymer (A1), for example, a raw material monomer solution composed of the monomers, and a polymerization reaction is performed. 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 to 1 part by mass based on 100 parts by mass of the total amount of raw material monomers. Thereafter, for example, a method of reacting at a reaction temperature of 40°C or higher and 90°C or lower (or 60°C or higher and 90°C or lower) in a nitrogen atmosphere for 3 hours to 10 hours is mentioned.

As the thermal polymerization initiator, 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-methylpropio) Nate), 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] hydrate, 2,2'-azobis [2-(2-imidazolin-2-yl )Propane], 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis [2-methyl-N-(2-hydroxy Azo compounds such as hydroxyethyl) propionamide]; t-butylperoxypivalate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxide, cumene hydroperoxide, benzoylperoxide, t-butylhydro Organic peroxides such as peroxide; And inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate. These thermal polymerization initiators may be used alone or as a mixture of more than one species.

In the bulk polymerization method using a photopolymerization initiator, for example, a raw material monomer and a photopolymerization initiator are added. Subsequently, the active energy ray is irradiated with a reaction start temperature of 20°C to 35°C in a nitrogen atmosphere. A method of obtaining a copolymer (A1) by stopping the reaction by introducing air into the reaction system or the like in a step where the temperature in the reaction system rises from 5°C to 15°C from the reaction start temperature is obtained.

Examples of active energy rays that can be used in the bulk polymerization method include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron beams. Ultraviolet rays can be preferably applied as the active energy ray from the viewpoints of controllability and handleability, and price. More preferably, ultraviolet rays having a wavelength of 200 nm or more and 400 nm or less may be used. Ultraviolet light can be irradiated using a high pressure mercury lamp, a microwave excitation lamp, a chemical lamp, or a black light source. The roughness is preferably in the 3.2mW / cm ² or less than 5.6mW / cm ^2.

Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, and 1-(4-isopropylphenyl)-2- Hydroxy-2-methyl propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1- Acetophenones such as phenylpropan-1-one; Benzophenones, including benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; Benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; Thioxanthones, such as 4-isopropyl thioxanthone; And 1-hydroxycyclohexylphenylketone, xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone. These photopolymerization initiators may be used alone or in combination of two or more.

A commercially available product may be used as a photopolymerization initiator, and examples of the commercial product include, for example, IRAGACURE (registered trademark) 184, 819, 907, 651, 1700, 1800, 819, 369, 261, DAROCUR (DAROCUR) ( TPO, 1173 (above, BASF Japan Co., Ltd.), Esacure (ESACURE) (registered trademark) KIP150, TZT (above, DKSH Japan Corporation), Kayacure (registered trademark) BMS, DMBI (above) , Japanese Chemicals Co., Ltd.) and the like.

The amount of the photopolymerization initiator used is preferably 0.0005 parts by mass or more and 1 part by mass or less, 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 the raw material monomers.

In addition, a chain transfer agent may be used to control 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 the like Mercaptans such as ester, 2-ethylhexyl thioglycol, and octyl thioglycolate; Alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol, and allyl alcohol; Halogenated hydrocarbons such as chloroethane, fluoroethane and trichloroethylene; Carbonyls such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butylaldehyde, furfural, and benzaldehyde; Methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, α-methylstyrene, and the like. These chain transfer agents may be used alone or in combination of two or more.

<silane coupling agent (B) having a plurality of isocyanate groups>

The adhesive for optical films of the present invention includes a silane coupling agent (B) having a plurality of isocyanate groups. Further, the silane coupling agent having a plurality of (B) isocyanate groups includes at least one compound selected from the group consisting of compounds represented by the following general formulas 1 to 4 having an isocyanurate skeleton. In the present invention, the following effects can be obtained by using a silane coupling agent (B) having a plurality of isocyanate groups having a specific structure. In other words, the wettability to glass and the crosslinking effect by a plurality of NCOs are simultaneously realized. In addition, it has an NCO crosslinked structure, and at the same time, flexibility can be secured. For this reason, the effect by crosslinking becomes large, and at the same time, stress relaxation is not impaired. For this reason, in the single-sided protective polarizing plate, the suppression force of shrinkage of the polarizer by the protective film becomes small, and the shrinkage due to heating or the like can be suppressed. As a result, generation of air bubbles can be suppressed at the edge portion, and peeling and lifting of the polarizing plate can be suppressed. Moreover, durability in harsh environments (high temperature, high humidity, and thermal 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 furthermore, reworkability (processability) It can provide an excellent adhesive. On the other hand, in this specification, "silane coupling agent" means a silane compound having a siloxane bond (Si-O-Si bond) and having two or more reactors in the molecule.

(Formula 1)

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.

(Formula 2)

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 , Y ² 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.

(Formula 3)

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 , Y ² is a group represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 4)

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 , Y ³ are groups represented by the following formula 5,

n and m are each independently an integer of 1 to 8,

a and b are each independently an integer of 0 or more and 3 or less.

(Formula 5)

In Equation 5, * denotes a part 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 crosslinking agent and the effect of stress relaxation, it is preferably an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms.

R ³ , R ⁵ , R ⁶ and R ⁹ are each independently an alkylene group having 1 to 8 carbon atoms. From the viewpoint of securing both the effect as a crosslinking 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.

In General Formula 1, R ⁴ is an alkylene group having 1 to 8 carbon atoms. From the viewpoint of ensuring both the effect as a crosslinking 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. In the general formula 1, when R ³ and R ⁴ are single bonds, the rework properties and stress relieving effects of the present invention may not be achieved.

R ⁴ and R ¹⁰ in the general formulas 2 to ⁴ are each independently an alkylene group having 1 to 16 carbon atoms. From the viewpoint of securing both the effect as a crosslinking agent and the effect of stress relaxation, it is preferably an alkylene group having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms.

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

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

It is preferable that the silane coupling agent (B) includes at least one compound selected from the group consisting of compounds represented by the following general formulas 1a to 4a. It is excellent in that the effect of the above-mentioned invention can be further improved by using these compounds.

(Formula 1a)

(Formula 2a)

(Formula 3a)

(Formula 4a)

The silane coupling agent (B) may be a commercial product or a synthetic product. As a commercial product of a silane coupling agent (B), X-12-1159L (made by Shin-Yetsu Chemical Industry Co., Ltd.) etc. is mentioned, for example.

The silane coupling agent (B) may 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, more preferably 0.001 parts by mass or more and 5 parts by mass or less, and more preferably 0.01 parts by mass with respect to 100 parts by mass of the polymer component (A) having a hydroxyl group. It is more preferable that it is 3 mass parts or less, 0.01 mass parts or more, and 1 mass parts 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 of being capable of exhibiting an effect on durability even when placed in a harsh environment. On the other hand, if the content of the silane coupling agent (B) is 10 parts by mass or less, it is preferable from the viewpoint that the deterioration of bubble generation due to heating derived from the low molecular weight compound is eliminated.

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

Nitrogen is replaced inside the reaction vessel having a stirrer, thermometer, and cooling tube, and hexamethylene diisocyanate (HDI) and 3-isocyanatepropyltriethoxysilane are injected together in a molar ratio of 2:1. Then, an isocyanurate catalyst (for example, tetramethylammonium cuprate) is added in an appropriate amount under heating (for example, to 70°C) and stirring. An isocyanurate reaction is stopped by adding an appropriate amount of phosphoric acid when the conversion rate reaches 25% by measuring the refractive index of the reaction solution. Further, the obtained isocyanurate-type polyisocyanate composition is heated (for example, heated at 100°C for 150 minutes).

Subsequently, the isocyanurate-type polyisocyanate composition is filtered. Thereafter, the unreacted HDI monomer and a part of 3-isocyanatepropyltriethoxysilane are removed by the first thin film distillation under the conditions of heating and decompression (for example, 160°C and 0.8 mmHg). The content of the HDI monomer and 3-isocyanatepropyltriethoxysilane 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). Thereafter, the remaining HDI monomer is removed by the second thin film distillation under the conditions of heating and decompression (for example, 160°C and 0.1 mmHg). The content of the HDI monomer in the isocyanurate-type polyisocyanate composition after the second thin film distillation is about 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). Thereby, the triethoxysilyl group containing isocyanurate type polyisocyanate (silane coupling agent (B)) represented by said general formula 1a can be obtained.

<At least one component (C) selected from a crosslinking agent and hardening agent which can react with the polymer component (A) having a hydroxyl group>

The pressure-sensitive adhesive for an optical film of the present invention is also referred to as at least one component (C) (hereinafter referred to as "crosslinking agent/curing agent component (C)") selected from a crosslinking agent and a curing agent capable of reacting with a polymer component (A) having a hydroxyl group. It is preferred to include. The crosslinking agent/curing agent component (C) reacts with the polymer component (A) having a hydroxyl group to form a crosslinking structure. For this reason, the crosslinking agent/curing agent component (C) can mainly contribute to adhesiveness (adhesiveness) and durability in the adhesive for optical films.

In the present invention, the crosslinking agent/curing agent component (C) contains at least one member 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 preferable. Hereinafter, these various crosslinking agents and hardening agent components (C) are demonstrated.

[Isocyanate compound]

In the present invention, specific examples of the isocyanate compound that can be used as the crosslinking agent/curing agent component (C) include dimer acid diisocyanate, 2,4-torylene diisocyanate (2,4-TDI), and 2,6-torylene di. Isocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4 -Aromatic diisocyanates such as phenylene diisocyanate, xylene diisocyanate (XDI), tetramethyl xylene diisocyanate (TMXDI), toluidine diisocyanate (TODI), and 1,5-naphthalene diisocyanate (NDI); Aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and norbornane diisocyanate methyl (NBDI); Fatty cyclic diisocyanates such as transcyclohexane 1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), and H12-MDI (hydrogenated MDI); Carbodiimide-modified diisocyanates of the diisocyanate; Or these isocyanurate-modified diisocyanates. Adducts of the isocyanate compounds and polyol compounds such as trimethylolpropane, polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), and burettes or isocyanurates of these isocyanate compounds can also be preferably used. .

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

As commercial products, for example, Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, Coronate (registered trademark) 2031 (or higher) , Tosoh Co., Ltd.), Coronate (registered trademark) D-102, TAKENATE (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 ( Above, Mitsui Chemical Co., Ltd., Duranate (registered trademark) 24A-100, Duranate (registered trademark) TPA-100, Duranate (registered trademark) TKA-100, Duranate (registered trademark) ) P301-75E, Duranate (registered trademark) E402-90T, Duranate (registered trademark) E405-80T, Duranate (registered trademark) TSE-100, Duranate (registered trademark) D-101, Duranate (registered trademark) ) D-201 (above, manufactured by Asahi Hwasung Co., Ltd.), SMIDULE (registered trademark) N-75, N-3200, N-3300 (above, manufactured by Sumika Kovesturo Urethane Co., Ltd.), Sanprene ( SANPRENE) (registered trademark) P-6090 (PTMG/MDI system), Sanprene (registered trademark) P-663L (PTMG/TDI system), Sanprene (registered trademark) P-664 (PTMG/TDI system), Sanprene (Registered trademark) P-665 (PTMG/TDI system), Sanprene (registered trademark) P-667 (PTMG/TDI system), Sanprene (registered trademark) P-868 (PTMG/HMDI system), Sanprene (registered trademark) Trademarks) P-870 (PTMG/HMDI system), Sanprene (registered trademark) C-810" (PPG/TDI system) (above, manufactured by Sanyo Chemical Co., Ltd.) and the like, but are not limited to these.

The isocyanate compound may be used in the form of an unblocked isocyanate compound. Further, the isocyanate compound may be used in the form of a blocked isocyanate compound obtained by reacting with a blocking agent protecting an isocyanate group. The block isocyanate compound may be a commercial product or a synthetic product. Commercially available products of the block isocyanate compound are, for example, DURANATE (registered trademark) MF-B60X (block 1,6-hexamethylene diisocyanate) manufactured by Asahi Chemical Co., Ltd., and DURANATE (registered trademark) MF-K60X ( Block 1,6-hexamethylene diisocyanate), Coronate (registered trademark) AP-M, 2503, 2507, 2513, 2515, MIRIONATE (registered trademark) MS-50 manufactured by Tosoh Corporation , Mitsui Chemical Co., Ltd. TAKANATE (registered trademark) B-830 (block tolylene diisocyanate), B-815N (block 4,4'-methylenebis (cyclohexyl isocyanate)), B-842N (block 1) ,3-bis(isocyanatemethyl)cyclohexane), B-846N (block 1,3-bis(isocyanatemethyl)cyclohexane), B-874N (block isophorone diisocyanate), B-882N (block 1, 6-hexamethylene diisocyanate), DIC Corporation's BARNOCK (registered trademark) D-500 (block torylene diisocyanate), D-550 (block 1,6-hexamethylene diisocyanate), Daiichi Industries ELASTRON (registered trademark) BN-P17 (block 4,4'-diphenylmethane diisocyanate), BN-04, BN-08, BN-44, BN-45 (above, manufactured by Pharmaceutical Co., Ltd.) Block urethane-modified polyisocyanates); and the like. Among these, Duranate (registered trademark) MF-K60X is preferable.

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

In addition, 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. The following effects can be obtained by including an isocyanate compound having such a number average molecular weight as a crosslinking agent/curing agent component (C).

In other words, while suppressing the compaction of the crosslinked structure of the polymer component (A) having a hydroxyl group, a slow crosslinking effect due to a long distance between the crosslinking points can be expressed. Thereby, it is possible to achieve both the suppression of air bubbles and the suppression of peeling at the edge portion more efficiently.

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

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 from 900 to 7,000, more preferably from 1,000 to 5,000. On the other hand, the number average molecular weight (Mn) of the isocyanate compound can be obtained 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 that can be used as the crosslinking agent/curing agent component (C) is not particularly limited. Given one example of a carbodiimide compound, a high molecular weight polycarbodiimide produced by subjecting a diisocyanate condensation reaction to diisocyanate in the presence of a carbodiimide catalyst is used.

Examples of the diisocyanate provided for the decarbonation condensation reaction include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, and 3,3'-dimethyl. -4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-torylene diisocyanate, 2 And 6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, and the like.

Further, examples of the carbodiimide catalyst that can be used in the decarbonation condensation reaction include, for example, 1-phenyl-2-phosphorene-1-oxide, 3-methyl-2-phosphorene-1-oxide, and 1-ethyl And phosphorene oxides such as -3-methyl-2-phosphorene-1-oxide, 1-ethyl-2-phosphorene-1-oxide, and 3-phosphorene isomers thereof.

The high molecular weight polycarbodiimide may be a commercial product or a synthetic product. Examples of commercial products include, for example, 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 have excellent compatibility with an organic solvent, and are preferable.

[Oxazoline compounds]

The oxazoline compound which can be used as a crosslinking agent/curing agent component (C) in the present invention is not particularly limited. The oxazoline compound contains an acrylic skeleton or a main chain composed of a styrene skeleton and includes an oxazoline group-containing acrylic/styrene polymer having an oxazoline group in the side chain of the main chain or a main chain composed of an acrylic skeleton, and oxazoline in the side chain of the main chain. An oxazoline group-containing polymer called an oxazoline group-containing acrylic polymer having a group is preferable.

As an oxazoline group, a 2-oxazoline group, 3-oxazoline group, 4-oxazoline group, etc. are mentioned, for example, Especially, 2-oxazoline group is preferable.

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

As the oxazoline group-containing polymer, specifically, EPOCROS (registered trademark) WS-300, Epocross (registered trademark) WS-500, Epocross (registered trademark) WS-700 manufactured by Nihon Shokubai Co., Ltd. Oxazoline group-containing acrylic polymers, oxazoline group-containing acrylic/styrene-based polymers such as Epocross (registered trademark) K-1000 series manufactured by Nihon Shokubai Co., Ltd., and E-pocross (registered trademark) K-2000 series. have.

[Epoxy compound]

In the present invention, the epoxy compound that can be used as the crosslinking agent/curing agent component (C) is not particularly limited, and a known epoxy-based crosslinking agent can be suitably employed. As commercially available products of the epoxy compound, for example, ``TETRAD (registered trademark)-C'' manufactured by Mitsubishi Gas Chemical Co., ``TETRAD (registered trademark)-X'', ``ADEKA RESIN'' manufactured by ADEKA Corporation Liquid Epoxy Resin, such as EPU series", "Adecar Resin (registered trademark) EPR series", "CELLOXIDE (registered trademark)" manufactured by Daicel Co., Ltd., and the like. These liquid epoxy resins are preferable in that the mixing operation when manufacturing the pressure-sensitive adhesive for an optical film becomes easy.

[Polyfunctional (meth)acrylic acid ester monomer]

The polyfunctional (meth)acrylic acid ester monomer is a (meth)acrylic acid ester monomer having a plurality of radically polymerizable functional groups. Such a compound can also be used as a crosslinking agent/curing agent component (C).

As a polyfunctional (meth)acrylic acid ester monomer, a hydrocarbon-type or hydrocarbon ether-type polyfunctional monomer is mentioned, for example. The hydrocarbon-based or hydrocarbon ether-based polyfunctional monomer is a compound having a (meth)acrylate of a hydroxyl group of a polyhydric alcohol having a hydrocarbon group or a hydrocarbon ether group having 10 to 100 carbon atoms as the main skeleton. These are preferable from the viewpoint of improving adhesion by crosslinking. Examples of the hydrocarbon group of the polyhydric alcohol include a straight-chain or branched-chain aliphatic hydrocarbon group, an aromatic hydrocarbon group, a fatty-cyclic hydrocarbon group, and a hydrocarbon group combining these hydrocarbon groups. As said hydrocarbon ether group, what etherified the said hydrocarbon group is mentioned. Further, examples of the polyhydric alcohol having a hydrocarbon ether group as the main skeleton include a compound having an alkylene oxide having 2 or more and 4 or less carbon atoms (addition number 1 or more and 30 or less), or an alkylene oxide having 2 or more and 4 carbon atoms or less. Polyalkylene glycol (addition number 1 or more and 30 or less) etc. which can be obtained are mentioned.

Specific examples of the hydrocarbon-based bifunctional monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediyl di(meth). Di(meth)acrylates of alkylene glycols such as acrylate and neopentyl glycol di(meth)acrylate; Di(meth)acrylates of diol compounds having a cycloaliphatic hydrocarbon group such as cyclohexanedimethanol di(meth)acrylate and tricyclodecanedimethanol di(meth)acrylate; And di(meth)acrylates of diol compounds having an aromatic hydrocarbon group such as bisphenol A di(meth)acrylate.

Further, specific examples of the hydrocarbon ether-based difunctional monomer include, for example, alkoxylated hexanedimethanol di(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate, alkoxylated di(meth)acrylate, Compounds in which alkylene oxides are added to alkylene glycols or diol compounds based on the above hydrocarbon-based bifunctional monomers such as alkoxylated neopentyl glycol di(meth)acrylate and alkoxylated bisphenol A di(meth)acrylate. Di(meth)acrylate etc. are mentioned. Further, specific examples of the hydrocarbon ether-based difunctional monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylic. And di(meth)acrylates of polyalkylene glycols such as acrylate, tripropylene glycol di(meth)acrylate, and dipropylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, and the like.

Moreover, as a trifunctional monomer or a tetrafunctional monomer of a hydrocarbon type or a hydrocarbon ether type, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glyceryl tri(meth)acrylate , Tri(meth)acrylate or tri(meth)acrylate of tri or tetraol compounds such as pentaerythritol tetra(meth)acrylate and trimethylolpropane tetra(meth)acrylate, or alkyl to the tri or tetraol compound And tri(meth)acrylate or tetra(meth)acrylate of the compound to which renoxide has been added.

Moreover, as a monomer other than the said hydrocarbon type or hydrocarbon ether type, polyester poly(meth)acrylate which has two or more (meth)acryloyl groups at the terminal, epoxy (meth)acrylate, etc. are mentioned.

〔peroxide〕

The peroxide that can be used as the crosslinking agent/curing agent component (C) in the present invention is not particularly limited, and a known substance can be used. In addition, in view of productivity and stability, the peroxide preferably has a half-life temperature of 80°C or more and 160°C or less, more preferably 80°C or more and 140°C or less, and also preferably 80°C or more and 125°C or less, and 90°C or more It is particularly preferable to be 125°C or lower. On the other hand, "half-life of peroxide" is an index indicating the decomposition rate of peroxide, and means the time until the residual amount of peroxide becomes half. The decomposition temperature for obtaining a half-life at a certain time or the half-life time at a certain temperature is described in the manufacturer's catalog, for example, in the 9th edition of the organic peroxide catalog published by Ilyu Corporation (NOF Corporation) (May 2003). It is described.

Examples of such peroxides are, for example, diisopropyl peroxydicarbonate (half-life temperature 88.3°C for 1 minute, hereinafter, the temperature in parentheses represents the half-life temperature for 1 minute), di(2-ethylhexyl)peroxydicarbonate (90.6°C), Bis(4-t-butylcyclohexyl)peroxydicarbonate (92.1℃), di-sec-butylperoxydicarbonate (92.4℃), t-butylperoxy neodecanoate (103.5℃), t-hexylperoxy Pivalate (109.1°C), t-butylperoxypivalate (110.3°C), dilauroyl peroxide (116.4°C), bis-n-octanoylperoxide (117.4°C), 1,1,3,3 -Tetramethylbutyl peroxy-2-ethylhexanoate (124.3℃), di(4-methylbenzoyl) peroxide (128.2℃), dibenzoyl peroxide (benzoyl peroxide) (130.0℃), and dibenzoyl peroxide And mixtures of benzoyl m-methylbenzoyl peroxide and m-toluoyl peroxide (131.1°C), t-butylperoxybutyrate (136.1°C), and the like. Among them, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, and t-butylperoxyneodecanoate can be preferably used. These may be used in only one type, but it is also preferable to use two or more types in combination from the viewpoint of controlling reactivity. As an example of using two or more kinds, a combination of di(4-t-butylcyclohexyl)peroxydicarbonate and dilauroyl peroxide is preferable.

As the peroxide, a commercial product or a synthetic product may be used. Commercially available products include, for example, Ilyu Co., Ltd. trade name: "PAROIL (registered trademark, same as hereinafter) IB" (85.1°C), "PARK MILL (registered trademark, hereinafter the same) ND" (94.0) ℃), "Paroyl NPP" (94.0°C), "Paroyl IPP" (88.3°C), "Paroyl SBP" (92.4°C), "Paokuta (registered trademark, hereinafter the same) ND" (92.4°C), ``Paroyl TCP'' (92.1°C), ``Paroyl OPP'' (90.6°C), ``Fahexyl (registered trademark, hereinafter the same) ND'' (100.9°C), ``Pabutyl (registered trademark, hereinafter the same) ND'' ( 103.5℃), "Pabutyl NHP" (104.6℃), "Pahexyl PV" (109.1℃), "Pabutyl PV" (110.3℃), "Paroyl 3 55" (112.6℃), "Paroyl L" (116.4 °C), "Paokuta O" (124.3 °C), "Paroyl SA" (131.8 °C), "Fahexa (registered trademark, same as hereinafter) 25O" (118.8 °C), "Fahexyl O" (132.6 °C) ), ``Nypa (registered trademark, same as hereinafter) PMB'' (128.2°C), ``Pabutyl O'' (134.0°C), ``Nypa BMT'' (131.1°C), ``Nypa BW'' (130.0°C), `` Naifa BMT-K40'' (131.1°C), ``Nipa BMT-M'' (131.1°C), ``Pahexa MC'' (142.1°C), ``Pahexa TMH'' (147.1°C), and ``Pahexa HC'' (149.2 ℃), "Pahexa C" (153.8 ℃), "Patetra (registered trademark, same as hereinafter) A" (153.8 ℃), "Pahexyl I" (155.0 ℃), "Pabutyl L" (159.4 ℃), "Pabutyl I" (158.8°C), "Pahexa 25Z" (158.2°C), "Pabutyl A" (159.9°C), "Pahexa 22" (159.9°C), and the like.

In the present invention, only one type of the crosslinking agent/curing agent component (C) may be used alone, or two or more types may be used in combination. When two or more types are combined, two or more of the same series of crosslinking agents and curing agent components (C) may be combined (for example, two types of isocyanate compounds), and one of the other series of crosslinking agents and curing agent components (C) may be combined. You may combine the above (for example, 1 type of isocyanate compound and 1 type of peroxide).

The content of the crosslinking agent/curing agent component (C) in the pressure-sensitive adhesive for an optical film of the present invention is not particularly limited, but is preferably 0.001 part 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, and 0.01 It is more preferable that it is 10 parts by mass or more, more preferably 0.03 parts by mass or more and 5 parts by mass or less, and particularly preferably 0.05 parts by mass or more and 3 parts by mass or less. When the content of the crosslinking agent/curing agent component (C) is 0.001 parts by mass or more, it is preferable from the viewpoint that air bubbles can be suppressed during heating durability. On the other hand, if the content of the crosslinking agent/curing agent component (C) is 20 parts by mass or less, it is preferable from the viewpoint that the crosslinking structure is not too dense and durability can be secured even in harsh environments.

<silane coupling agent not containing an isocyanate group (D)>

It is preferable that the adhesive for optical films of this invention further contains the silane coupling agent (D) which does not contain an isocyanate group. The silane coupling agent (D) that does not contain an isocyanate group can mainly contribute to improvement in durability and adhesion to glass when the skin complex is glass in the adhesive for optical films.

In the present invention, the silane coupling agent (D) that does not contain an isocyanate group is not particularly limited, but specifically, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and methyltrimethoxysilane , Dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane,

n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, cyclohexylmethyldimethoxysilane, vinyltrichlorosilane, vinyltri Methoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ- Methacryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyl Dimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ -Aminopropyl triethoxysilane, N-phenyl-γ-aminopropyl trimethoxysilane, γ-chloropropyl trimethoxysilane, γ-mercaptopropyl trimethoxysilane, γ-mercaptopropyl methyl dimethoxysilane, etc. Can be heard.

In addition, a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), an amino group, a mercapto group, or a (meth)acryloyl group, and a silane coupling agent containing a functional group reactive with the functional group thereof, other coupling agents, etc. A compound having a hydrolyzable silyl group that can be obtained by reacting each functional group at an arbitrary ratio can also be used. Preferably, the silane coupling agent (D) containing no isocyanate group may include a silane coupling agent having an epoxy group such as a glycidoxy group.

The silane coupling agent (D) that does not contain the isocyanate group may be a commercial product or a synthetic product. As commercially available products of the silane coupling agent (D), for example, KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, KBM-802, KBM And -803, KBE-846 (above, manufactured by Shinyetsu Chemical Industry Co., Ltd.).

The silane coupling agent (D) that does not contain the isocyanate group may be used alone or in combination of two or more.

When the pressure-sensitive adhesive for an optical film of the present invention contains a silane coupling agent (D) that does not contain an isocyanate group, the content of the silane coupling agent (D) is not particularly limited, but is 0.001 to 100 parts by mass of the polymer component (A) having a hydroxyl group It is preferable that it is 10 parts by mass or more, more preferably 0.001 parts by mass or more and 5 parts by mass or less, and still more preferably 0.01 parts by mass or more and 3 parts by mass or less. 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 of being capable of exhibiting an effect on durability even when placed in a harsh environment. On the other hand, if the content of the silane coupling agent (D) that does not contain an isocyanate group is 10 parts by mass or less, it is preferable from the viewpoint that the deterioration of bubble generation upon heating derived from the low molecular weight compound is eliminated.

<Other additive components>

If necessary, the pressure-sensitive adhesive for an optical film of the present invention may contain a known additive component (other additive component) within a range that does not impair the effects of the invention. Although it is not particularly limited as a known additive component, for example, a solvent, a crosslinking accelerator, an anti-aging agent, a filler, a colorant (pigment or dye), an ultraviolet absorber, an antioxidant, a chain transfer agent, a plasticizer, a softener, a surfactant, an antistatic agent And the like.

<solvent>

The adhesive for optical films of the present invention may contain a solvent. By including the solvent, a significant improvement effect in productivity at the time of coating can be obtained. Although it does not specifically limit as a solvent, 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; Fatty cyclic hydrocarbons such as cyclohexane and methylcyclohexane; And organic solvents such as ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetone. These solvents may be used alone or in combination of two or more.

<Method for preparing (preparing) an adhesive for optical films>

When the adhesive for optical films which concerns on this invention contains the component other than the polymer component (A) which has a hydroxyl group and the polymer component (A) which has a hydroxyl group, it can prepare by mixing each component. Meanwhile, the mixing order of each component, the mixing temperature, and the like are not particularly limited, and can be appropriately adjusted by those skilled in the art.

[purpose]

The above-mentioned adhesive for optical films of the present invention is suitable for various uses. For example, it can be preferably used for an optical member such as an optical film. In particular, it can be preferably used in thin adhesive optical films used in large-sized liquid crystal panels. Examples of the optical film include a polarizing plate, a retardation plate for preventing coloration, an optical compensation film such as a viewing angle enlargement film for improving the viewing angle of a liquid crystal display, and a brightness enhancing film for increasing the contrast of the display, and those laminated thereon.

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

<Adhesive layer>

According to one embodiment of the present invention, the pressure-sensitive adhesive layer for an optical film formed of the above-mentioned pressure-sensitive adhesive for an optical film of the present invention is provided.

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 use. The thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 75 μm or less, more preferably 5 μm or more and 40 μm or less, particularly preferably 7 μm or more and 35 μm or less And most preferably 10 μm or more and 30 μm or less. If the thickness of the pressure-sensitive adhesive layer is within the above range, it is preferable from the viewpoint of having a good balance between durability and adhesion properties.

The gel fraction immediately after drying of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 95% or less from the viewpoint of punching or slit processing. Moreover, it is preferable that it is 40% or more from a viewpoint which does not require an aging treatment, since the concern about the puncture, warping, or durability of the pressure-sensitive adhesive layer immediately after drying disappears, 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 crosslinking agent, or the amount of peroxide.

The initial adhesive strength of the pressure-sensitive adhesive layer of the present invention may be 1.2 to 4.0 N/25 mm, preferably 1.3 to 3.9 N/25 mm, and more preferably 2.2 to 3.6 N/25 mm. The adhesive strength after heating of the pressure-sensitive adhesive layer of the present invention may be 2.0 to 5.0 N/25 mm, preferably 2.5 to 5.0 N/25 mm. Within the above range, rework property may be excellent. The'initial adhesive force' and'adhesive force after heating' may be measured by the method described below.

(Method for manufacturing adhesive layer)

According to another aspect of the present invention, a method of manufacturing the pressure-sensitive adhesive layer for an optical film comprising applying the above-mentioned pressure-sensitive adhesive for an optical film of the present invention onto a release sheet, followed by heat treatment and crosslinking reaction.

When using an adhesive in an optical film, you may apply an adhesive directly on an optical film, and you may form an adhesive layer. Among them, it is preferable to apply the pressure-sensitive adhesive on a film having releasability to form the pressure-sensitive adhesive layer and then transfer it to various optical films for use. In addition, the film having the releasability to which the pressure-sensitive adhesive layer prepared in this way is added can also be wound together in a manufacturing process to be rolled. In addition, after making it into a roll state, when it cuts or processes as needed and sticks to various optical films, liquid crystal panels, etc., the film which has the said mold release property can be removed and used. Additionally, a film having release properties until the pressure-sensitive adhesive layer is provided for practical use can also serve to protect the pressure-sensitive adhesive layer. In this specification, the film having such a release property is also referred to as a release sheet (separator).

As the constituent material of the release sheet, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and non-woven fabrics, nets, foam sheets, metal foils, and laminates thereof And suitable thin bodies. A plastic film can be preferably used as the constituent material of the release sheet in that it has excellent surface smoothness.

Moreover, the thickness of a release sheet is 5 micrometers or more and 200 micrometers or less normally, Preferably it is about 5 micrometers or more and 100 micrometers or less.

If necessary, the release sheet may be subjected to an antistatic treatment such as a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, anti-fouling treatment, anti-fouling treatment, coating type, kneading type, deposition type, etc. Can be. In particular, it is preferable to perform a peeling treatment such as silicone treatment, long chain alkyl treatment, fluorine treatment on the surface of the release sheet. This is for improving the peelability of the said adhesive layer.

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

In the manufacturing method of the adhesive layer of this invention, the process of heat-processing, after apply|coating the above-mentioned adhesive for optical films on a release sheet is performed. The related heat treatment step not only removes the solvent in the coating film obtained by coating by drying, but also serves to cross-link the pressure-sensitive adhesive for an optical film described above. The temperature of the heat treatment is preferably 40°C or more and 150°C or less, more preferably 50°C or more and 130°C or less, and more preferably 80°C or more and 120°C or less. By setting the temperature of the heat treatment within the above range, an adhesive layer having excellent adhesive properties can be obtained.

Further, the time for the heat treatment can be appropriately set, but is preferably 5 seconds or more and 20 minutes or less, more preferably 5 seconds or more and 10 minutes or less, and more preferably 10 seconds or more and 5 minutes or less.

Moreover, it does not specifically limit as a means of heat processing, Various well-known methods can be used. For example, a parallel drying method in which hot air is blown in the same direction of the film in the same direction up and down, a counter drying method in which hot air is blown in the conveying direction of the film in different directions up and down, hot air directly from the top and bottom of the film And a float drying method for blowing air.

[Absence of optics]

According to one aspect of the present invention, an optical member having the above-described pressure-sensitive adhesive layer for optical films and a first optical film formed on one side of the pressure-sensitive adhesive layer is provided.

In addition, according to one embodiment of the present invention, the first optical film formed on one side of the pressure-sensitive adhesive layer for the optical film and the pressure-sensitive adhesive layer and the glass or second optical film formed on one side of the pressure-sensitive adhesive layer are already provided. An optical member having is provided. In addition, here, "the 1st optical film" and "the 2nd optical film" may be a film which has the same structure (material, function, etc.), or a film which has a different structure (material, function, etc.). Further, in the present invention, a form in which the first optical film (or the second optical film) is a polarizing plate is also provided.

In the present invention, the above-described pressure-sensitive adhesive may be used by directly applying to one side or both sides of an optical film to form an pressure-sensitive adhesive layer. In the present invention, it is preferable to use the above-mentioned reason by forming an adhesive layer in a separator or the like in advance and transferring it to one side or both sides of the optical film. In addition, a basic treatment such as the formation of an easily adhesive treatment layer or the formation of an antistatic layer may be performed on the surface of the optical film before transfer. Moreover, you may perform an easily adhesive process also on the surface of an adhesive layer. From the viewpoint of strongly adhering the optical film and the pressure-sensitive adhesive layer, it is preferable to provide a self-adhesive treatment layer between the optical film and the pressure-sensitive adhesive layer for an optical film of the present invention.

<Easy adhesive treatment layer (easy adhesive layer)>

It is preferable that the optical member of the present invention further has at least one self-adhesive treatment layer between the first optical film and the pressure-sensitive adhesive layer for optical films.

In addition, as a more preferable aspect, the optical member of the present invention comprises a first self-adhesive treatment layer and a second self-adhesive in order from the first optical film side between the first optical film and the pressure-sensitive adhesive layer for the optical film. It has a treatment layer. The structure having both the first and second easily-adhesive treatment layers in the optical member is preferable from the viewpoint of bonding the optical film and the pressure-sensitive adhesive layer more strongly.

As the adhesive treatment layer, a surface of a member contacting the adhesive layer such as corona treatment or plasma treatment may be treated. Further, as the easily-adhesive 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.

It is preferable that the material constituting the primer layer forms a film having good adhesion to a member in contact with the primer layer and having excellent cohesion. As the material constituting the primer layer, various polymers, metal oxide sol, silica sol, and the like can be used. Among them, polymers can be preferably used. The primer layer may have an antistatic function.

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

As the oxazoline group-containing polymer, commercially available products can be used. For example, the EPOCROS (registered trademark) series (for example, Epocross (registered trademark) WS700) manufactured by Nihon Shokubai Co., Ltd. is mentioned, but is not limited to this. Further, for the polyurethane resin, polyester resin, polymers containing amino groups in the molecule, etc., materials disclosed in paragraphs "0107" to "0113" of JP 2011-105918 A may be suitably employed.

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

The method of forming the primer layer is not particularly limited, and the primer layer can be formed by coating and drying the raw material (coating agent) of the primer layer using a coating method such as a coating method, a dipping method, or a spray method.

<optical film>

In the present invention, the optical film (first optical film or second optical film) includes an optical compensation film such as a polarizing plate, a retardation plate for preventing coloration, a viewing angle enlargement film for improving the viewing angle of a liquid crystal display, and the contrast of the display. And a luminance-enhancing film for raising the product, a product on which they are laminated, and the like, but are not limited to these. Preferably, the optical film (first optical film or second optical film) is a polarizing plate. Hereinafter, a polarizing plate is demonstrated.

(Polarizing plate)

In the present invention, a polarizing plate preferable as an optical film is one in which a protective film and a polarizer are bonded to each other using an adhesive by a conventionally known method. After that, it can be produced by heat drying or curing by ultraviolet rays, electron beams, or the like. The coating adhesive forms an adhesive layer by exhibiting adhesiveness by drying or curing under ultraviolet rays or electron beams.

There is no restriction|limiting in particular as a polarizer, A conventionally well-known substance can be used. For example, a single axis is obtained by adsorbing dichroic materials such as iodine or dichroic dye to hydrophilic polymer films such as polyvinyl alcohol-based films, partially-formylated polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. And a polyene-based alignment film such as a stretched product, a dehydration product of polyvinyl alcohol, or a dehydrochloric acid product of polyvinyl chloride.

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

As a method of immersing in an aqueous solution of iodine, for example, it is preferable to immerse in an aqueous solution containing iodine and/or potassium iodide having a concentration of 0.1% by mass or more and 10% by mass or less. Moreover, if necessary, you may immerse in 50 degreeC or more and 70 degreeC or less aqueous solution, such as boric acid or potassium iodide, or you may immerse in water of 25 degreeC or more and 35 degreeC or less for washing|cleaning and stain stain prevention. Stretching may be performed after dyed with iodine, or may be stretched while dyed, or may be dyed with iodine after stretching. After dyeing and stretching, water may be washed, if necessary, and dried at 35°C or higher and 55°C or lower for about 1 minute to 10 minutes. These polarizers can also be obtained as commercial products from various types.

In addition, although the thickness of the polarizer is not particularly limited, it is generally 3 µm or more and 80 µm or less, and preferably 10 µm or more and 25 µm or less. When the thickness of the polarizer is 25 µm or less, the single-sided protective polarizing plate can contribute to the shrinkage suppression force of the polarizer by the protective film.

As a result, shrinkage due to heating can be suppressed, and it is possible to further suppress the generation of bubbles at the edge portion and peeling and lifting of the polarizing plate.

From the viewpoint of requiring higher durability as an optical film in the present invention, a polarizing plate having one or both surfaces protected as an optical film is preferable. Especially, a polarizing plate (one-sided protective polarizing plate) with one side protected as an optical film is more preferable. The method of protection is not particularly limited, and a known method such as bonding a protective film can be suitably employed.

As the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy and the like is preferable. For example, acrylic resins, cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefins And (meth)acrylic resins such as resins and polymethyl methacrylates, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, epoxy resins, and mixtures thereof.

Meanwhile, a transparent protective film may be bonded to one side of the polarizer by an adhesive. On the other side of the polarizer, a transparent protective film can be bonded by an adhesive or a protective layer is formed. As a protective layer, it can be formed using (meth)acrylic-type, urethane-based, acrylic urethane-based, epoxy-based, silicone-based thermosetting resins 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 is preferably 100 µm or less from the viewpoint of thinning. Such a thin polarizing plate is preferable from the viewpoint of more remarkably expressing the effect of the pressure-sensitive adhesive of the present invention.

The manufacturing method of a polarizing plate is not specifically limited, For example, after apply|coating an adhesive agent, it can be performed by making a polarizer and a protective film stick to each other with a roll laminator. After adhering to each other, a drying process may be appropriately performed, or a curing process may be performed in ultraviolet rays or electron beams. Moreover, when apply|coating an adhesive agent, you may apply to either a protective film or a polarizer, or you may apply to both sides. The adhesive is preferably coated such that the thickness of the adhesive layer after drying becomes 10 nm or more and 10 μm or less. In addition, it is not particularly limited as an adhesive, and can be suitably used as a known material in accordance with the material of the polarizer. For example, when using a polyvinyl alcohol-based film as a polarizer, an acrylic, epoxy, or acrylic-epoxy watch can be used as a polyvinyl alcohol-based adhesive or an ultraviolet curing adhesive. The thickness of the adhesive layer is preferably 10 nm or more and 200 nm or less in the polyvinyl alcohol-based adhesive, and preferably 0.2 μm or more and 10 μm or less in the ultraviolet curing adhesive. This is because if the thickness of the adhesive layer is within the above range, a uniform in-plane thickness can be obtained and at the same time sufficient adhesive strength can be obtained.

In the present invention, an adhesive polarizing plate on which an adhesive layer is formed may also be provided. On the other hand, the structure, manufacture, and the like of the pressure-sensitive adhesive polarizing plate are the same as those of the optical film having the pressure-sensitive adhesive layer described above, and thus description thereof is omitted here.

[Image display device]

The present invention also provides an image display device using at least one of the aforementioned optical members.

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

Example

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 to the following examples.

In addition, unless otherwise indicated in the following operation, measurement of operation, physical properties, and the like was set to conditions of 23°C and 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 Preparation Example was measured by gel permeation chromatography (GPC) (see below for measurement conditions).

Analytical device: manufactured by Tosoh Corporation, HLC-8120GPC

Column: Tosoh Corporation, G7000HXL+GMHXL+GMHXL

Column size: Each 7.8mmφ×30cm total 90cm

Column temperature: 40℃

Flow rate: 0.8 ml/min

·Injection amount: 100µl

· Eluent: Tetrahydrofuran

Detector: Differential Refractometer (RI)

Standard sample: Polystyrene.

(Production of single-sided protective polarizer)

A polyvinyl alcohol film having a thickness of 45 µm was placed between rolls having different speed ratios, and stretched up to 3 times while dying for 1 minute in an iodine solution at a concentration of 0.3% by mass at 30°C. Then, the film stretched up to 3 times was stretched until the total draw ratio became 6 times while immersing for 0.5 minute in an aqueous solution containing 60°C, 4 mass% concentration of boric acid and 10 mass% concentration of potassium iodide. Then, the film stretched up to 6 times was washed by immersion in an aqueous solution containing potassium iodide at a concentration of 1.5% by mass at 30°C for 10 seconds. Then, it dried at 50 degreeC for 4 minutes, and obtained the polarizer. A uniaxially stretched PET film having a thickness of 80 μm (a PET film of Cosmoshine (registered trademark) Super Birefringence Type (SRF) manufactured by Dongyang Co., Ltd.) was attached to one side of the polarizer with a polyvinyl alcohol adhesive, and the total thickness was 98 μm. A thin polarizing plate having a single-sided protection (often referred to as a single-sided protective polarizing plate) was produced.

[Production Example 1: Preparation of solution of (meth)acrylic acid ester copolymer (A1)]

The following copolymer raw materials and the like were injected into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. In other words, 50 parts by mass of n-butyl acrylate (manufactured by Nihon Shokubai Co., Ltd.), 49 parts by mass of 2-ethylhexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 4-hydroxybutyl acrylate (Osaka Organic Chemical Industry) Co., Ltd.) 1 part by mass and 0.1 part by mass of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator were injected together with 122.2 parts by mass of ethyl acetate. Thereafter, nitrogen gas was introduced with gentle stirring. After nitrogen gas substitution, the temperature of the liquid in the flask was maintained at around 55°C, and polymerization was performed for 4 hours. Thus, a solution of the (meth)acrylic acid ester copolymer (A1) with a weight average molecular weight (Mw) of 1,125,000 was prepared.

[Production Example 2: Preparation of a solution of (meth)acrylic acid ester copolymer (A2)]

In Production Example 1, the same operation as in Production Example 1 was performed except that the type and composition ratio of each monomer forming the (meth)acrylic acid ester copolymer was changed as shown in Table 1 below. Thus, a solution of a (meth)acrylic acid ester copolymer (A2) with a weight average molecular weight (Mw) of 1.3 million was prepared.

[Production Example 3: Preparation of solution of (meth)acrylic acid ester copolymer (A3)]

In Production Example 1, the same operation as in Production Example 1 was performed except that the type of each monomer forming the (meth)acrylic acid ester copolymer and its composition ratio were changed as shown in Table 1 below. Thereby, a solution of (meth)acrylic acid ester copolymer (A3) with a weight average molecular weight (Mw) of 12.5 million was prepared. Table 1 also shows the glass transition temperature (Tｇ) and the weight average molecular weight (Mｗ) of (meth)acrylic acid ester copolymer (A1) to (A3). The blank in Table 1 means that the corresponding monomer is not used.

Copolymer number Monomer composition (parts by mass) AIBN
(Parts by mass) Tg(℃) Mw
X 10 ⁴ (a1)
BA (a1)
2EHA (a2)
4HBA (a3)
AA (a4)
EHDG-AT Preparation Example 1 A1 50 49 One 0.1 -49.9 125 Preparation Example 2 A2 99.4 0.1 0.5 0.1 -44.5 130 Preparation Example 3 A3 50 29 One 20 0.1 -52.5 125

Note) BA: n-butyl acrylate (Japanese catalyst, Tg of homopolymer: -45°C)

2EHA: 2-ethylhexyl acrylate (Japanese catalyst, Tg of homopolymer: -68°C)

4HBA: 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., Tg of homopolymer: -32°C)

AA: acrylic acid (Japan catalyst, Tg of homopolymer: 106°C)

EHDG-AT: 2-ethylhexyl-diglycol acrylate (Tg: -67°C of Homopolymer, manufactured by Kyoeisha Chemical Co., Ltd.)

[Synthesis Example 1: Compound represented by general formula 1a: Synthesis method of silane coupling agent (B)]

Nitrogen was replaced inside the four-necked flask equipped with a stirrer, a thermometer, and a cooling tube, and raw materials for a compound represented by the following general formula 1a were injected. In other words, 336.40 g (2 moles) of hexamethylene diisocyanate (HDI, molecular weight = 168.20) and 3-isocyanate propyl triethoxysilane (KBE-9007 manufactured by Shin-Yetsu Chemical Co., Ltd., molecular weight = 205.28) 205.28 g (1 mole) It was injected. Thereafter, 0.1 g of tetramethylammonium cuprate was added as an isocyanurate catalyst under stirring at 70°C. The isocyanurate reaction was stopped by adding 0.2 g of phosphoric acid when the conversion ratio reached 25% by measuring the refractive index of the reaction solution. Furthermore, the obtained isocyanurate-type polyisocyanate composition was heated at 100 degreeC for 150 minutes. Here, the refractive index of the reaction solution was measured by an Abbe refractometer to measure the refractive index n ₂₀ ^D. The conversion rate was calculated from the obtained refractive index.

Subsequently, the isocyanurate type polyisocyanate composition obtained above was filtered. Thereafter, a portion of the unreacted HDI monomer and 3-isocyanatepropyltriethoxysilane were removed by first thin film distillation under conditions of 160°C and 0.8 mmPa. The total content of the HDI monomer and 3-isocyanatepropyltriethoxysilane 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. Thereafter, the remaining HDI monomer was removed by 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 mass%. The isocyanurate-type polyisocyanate composition after the second thin film distillation was heat treated at a temperature of 90° C. for 180 minutes. Thereby, an isocyanurate type polyisocyanate containing a triethoxysilyl group was obtained as a silane coupling agent (B). The triethoxysilyl group-containing isocyanurate-type polyisocyanate obtained was a compound having a structure represented by General Formula 1a.

When using the compound represented by the general formula 1a as in Synthesis Example 1 as the silane coupling agent (B) in the following examples, commercially available products X-12-1159L (silane coupling agent of the compound represented by the general formula 1a, Shin-Etsu Chemical Industry Co., Ltd.) was used for the experiment.

[Synthesis Example 2: Compound represented by general formula 2a: Synthesis method of silane coupling agent (B)]

Silane coupling agent in the same manner as in Synthesis Example 1, except that 205.28 g (1 mole) of HDI 504.60 g (3 moles) and 3-isocyanatepropyl triethoxysilane (KBE-9007 manufactured by Shin-Yetsu Chemical Industry Co., Ltd.) were injected as the injection amount. As (B), an isocyanurate-type polyisocyanate containing a triethoxysilyl group of the compound represented by the general formula 2a was obtained.

[Synthesis Example 3: Compound represented by general formula 3a: Synthesis method of silane coupling agent (B)]

Silane coupling agent in the same manner as in Synthesis Example 1, except that 410.56 g (2 moles) of HDI 336.40 g (2 moles) and 3-isocyanatepropyl triethoxysilane (KBE-9007 manufactured by Shinyetsu Chemical Industry Co., Ltd.) were injected as the injection amount. As (B), an isocyanurate-type polyisocyanate containing a triethoxysilyl group of the compound represented by General Formula 3a was obtained.

[Synthesis Example 4: Compound represented by general formula 4a: Synthesis method of silane coupling agent (B)]

Silane coupling agent in the same manner as in Synthesis Example 1, except that 410.56 g (2 mol) of HDI 504.60 g (3 mol) and 3-isocyanatepropyl triethoxysilane (KBE-9007 manufactured by Shin-Yetsu Chemical Industry Co., Ltd.) were injected as the injection amount. As (B), an isocyanurate type polyisocyanate containing a triethoxysilyl group of the compound represented by General Formula 4a was obtained.

<Example 1>

(Preparation of adhesive for optical film)

Silane coupling agent having a plurality of isocyanate groups 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 (i.e., 100 parts by mass of the (meth)acrylic acid ester copolymer (A1)) As (B), 0.2 parts by mass of X-12-1159L (containing 90% by mass of the compound represented by the general formula 1a, manufactured by Shin-Yetsu Chemical Co., Ltd.) was blended to prepare an adhesive for optical film (18% by mass of solid content).

(Formation of adhesive layer)

The thickness of the pressure-sensitive adhesive layer after drying was 25 on one side of a polyethylene terephthalate (PET) film (Mitsubishi Chemical Co., Ltd., MRF38, without oligomer prevention layer) having a thickness of 38 µm subjected to silicone treatment of the pressure-sensitive adhesive for optical film obtained above. It was coated to be µm. Then, the pressure-sensitive adhesive coated on the film was heat-treated at 110°C for 4 minutes to form the pressure-sensitive adhesive layer of Example 1. On the other hand, the heat treatment was performed by a float drying method of blowing hot air directly from the top and bottom of the film.

(Production of Optical Member (One-sided protective polarizing plate with adhesive layer added))

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

<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 an optical film, a silane coupling agent (B) having a plurality of isocyanate groups (in the comparative example, does not correspond to the silane coupling agent (B)) Examples include those used), crosslinking agent/curing agent component (C), silane coupling agent (D) containing no isocyanate group (in the comparative example, examples using those not corresponding to silane coupling agent (B) (D) are included. ), and the optical member corresponding to Examples 2 to 18 and Comparative Examples 1 to 8 (a single-sided protective polarizing plate with an adhesive layer added) in the same manner as in Example 1, except that the type and the amount of addition (compounding amount) were changed. Produced.

Copolymer
(A) Type Si coupling agent containing multiple NCOs (B) Crosslinking agent (C) Si coupling agent (D) Kinds Compounding amount
(Parts by mass) Kinds Compounding amount
(Parts by mass) Kinds Compounding amount
(Parts by mass) Example 1 Preparation Example 1 X-12-1159L 0.2 - - - - Example 2 Preparation Example 1 X-12-1159L 0.1 D-110N 0.1 - - Example 3 Preparation Example 1 X-12-1159L 0.1 D-110N 0.1 KBM-403 0.1 Example 4 Preparation Example 2 X-12-1159L 0.2 - - - - Example 5 Preparation Example 2 X-12-1159L 0.1 D-110N 0.1 - - Example 6 Preparation Example 2 X-12-1159L 0.1 D-110N 0.1 KBM-403 0.1 Example 7 Preparation Example 3 X-12-1159L 0.2 - - - - Example 8 Preparation Example 3 X-12-1159L 0.1 D-110N 0.1 - - Example 9 Preparation Example 3 X-12-1159L 0.1 D-110N 0.1 KBM-403 0.1 Example 10 Preparation Example 1 Formula 2a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Example 11 Preparation Example 2 Formula 2a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Example 12 Preparation Example 3 Formula 2a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Example 13 Preparation Example 1 Formula 3a 0.1 D-110N 0.1 KBM-403 0.1 Example 14 Preparation Example 2 Formula 3a 0.1 D-110N 0.1 KBM-403 0.1 Example 15 Preparation Example 3 Formula 3a 0.1 D-110N 0.1 KBM-403 0.1 Example 16 Preparation Example 1 Formula 4a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Example 17 Preparation Example 2 Formula 4a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Example 18 Preparation Example 3 Formula 4a 0.05 effective in small amounts D-110N 0.1 KBM-403 0.1 Comparative Example 1 Preparation Example 1 - - D-110N 0.1 - - Comparative Example 2 Preparation Example 1 - - D-110N 0.1 KBM-403 0.1 Comparative Example 3 Preparation Example 1 - - D-110N 0.1 KBE-9007 0.1 Comparative Example 4 Preparation Example 2 - - D-110N 0.1 Comparative Example 5 Preparation Example 2 - - D-110N 0.1 KBM-403 0.1 Comparative Example 6 Preparation Example 2 - - D-110N 0.1 KBE-9007 0.1 Comparative Example 7 Preparation Example 1 Equation (7) in paragraph 1 of document 1 0.1 D-110N 0.1 KBM-403 0.1 Comparative Example 8 Preparation Example 2 Equation (7) in paragraph 1 of document 1 0.1 D-110N 0.1 KBM-403 0.1

In Table 2 above,

1. (B), (C), (D) Addition amount of a component (unit: mass part) means the addition amount when the copolymer (A) is 100 mass parts.

2. "-" in the table means that the related components are not blended.

3. "D-110N" is a product of Mitsui Chemical Co., Ltd. (TAKANATE (registered trademark) D-110N, a 75% by weight ethyl acetate solution of trimethylolpropane adduct of xylene diisocyanate, isocyanate group in one molecule) Number: 3).

4. 「KBM-403」is a product of Shinyetsu Chemical Industry Co., Ltd. (3-glycidoxypropyl trimethoxysilane).

5. 「KBE-9007」: This is a product of Shinyetsu Chemical Co., Ltd. (3-isocyanatepropyltriethoxysilane).

6. "X-12-1159L" is a product of Shinyetsu Chemical Co., Ltd. (a compound represented by the general formula 1a; a silane coupling agent having an isocyanurate skeleton having a plurality of isocyanate groups).

7. "Formula (7) of document 1 paragraph "0063"" is a silane coupling agent which has an isocyanate group represented by formula (7) represented by paragraph "0063" of patent document 1.

[evaluation]

The following evaluation was performed on the single-sided protective polarizing plate (sample) with the pressure-sensitive adhesive layer for optical films produced by Examples 1 to 18 and Comparative Examples 1 to 8 and the pressure-sensitive adhesive layer as an optical member.

<Edge bubble>

The optical members (one-sided protective polarizer added with the adhesive layer) produced in Examples 1 to 18 and Comparative Examples 1 to 8 were cut into 37-inch sizes to be referred to as samples. The cut sample was attached to an alkali-free glass having a thickness of 0.7 mm (manufactured by Corning, Eagle XG) using a laminator. Then, autoclaving was performed at 50°C and 0.5 MPa for 15 minutes, and the sample was completely adhered to an alkali free glass. Samples subjected to this treatment were provided in the durability tests of (1) and (3) below, and the appearance between the polarizing plate (the polarizer side on which the adhesive layer was formed) and the glass after each test was evaluated visually based on the following criteria. . In this evaluation, bubbles generated within 1 mm of the edge portions on both sides of the stretching direction side of the polarizing plate were observed.

-Visual evaluation-

◎: There are no bubbles newly generated at the edge.

○: A little, but there are air bubbles generated at the edges, but there are no practical problems.

△: There is air bubble generated at the edge, but there is no problem in practical use unless it is a special purpose.

×: There is a significant number of bubbles on the edge, which is a practical problem.

<durability>

Samples treated in the same manner as the bubbles in the edges are provided in the durability tests of (1) to (3) below, and the appearance between the polarizing plate (the polarizer surface side where the adhesive layer is formed) and the glass after each test is as follows. As assessed by Moxie. In this evaluation, the entire polarizing plate was observed visually.

(1) Treatment at 85°C for 500 hours (heating test)

(2) It was treated for 500 hours under an atmosphere of 60°C and a relative humidity of 95% RH (humidification test).

(3) After leaving for 30 minutes in an environment at 85°C, leaving for 30 minutes in an environment at -40°C was treated as a cycle (1 hour), and a total of 300 cycles (300 hours) were processed (thermal shock (HS) test).

-Visual evaluation-

◎: There is no change in appearance such as air bubbles, peeling, and no lifting.

(Circle): There is little peeling or air bubbles at the edges, but there are no practical problems.

(Triangle|delta): There exists a peeling off or a bubble in an edge part, but there is no practical problem unless it is a special use.

X: There is a remarkable peeling off at the edge, and there is a problem in practical use.

<Reworkability>

Example 1 to Example 18 and Comparative Examples 1 to 8, the optical member produced by Comparative Example 8 was cut to a width of 25 mm × length of 100 mm, sample 1, 420 mm length × 320 mm width of the cut sample 2 (3 pieces produced) Said. This sample 1 and sample 2 were each attached to an alkali-free glass plate having a thickness of 0.7 mm (manufactured by Corning, Eagle XG) using a laminator, followed by autoclaving at 50°C and 506.5 Pa (5 atm) for 15 minutes. It was completely adhered (initial). Then, it heat-processed for 48 hours under 50 degreeC drying conditions (after heating).

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

Moreover, about the said sample 2 (3 sheets), the sample was peeled from the alkali free glass plate with a human hand, and the rework property was evaluated by the following criteria (actual rework property).

-Evaluation standard-

◎: Even 3 sheets can be peeled off without adhesive residue or film breakage.

○: Some of the three films were broken, but they could be peeled off again.

(Triangle|delta): All three pieces of film were broken, but could peel again by peeling again.

X: All three sheets were left with an adhesive residue, or even if peeled off several times, the film was broken and could not be peeled off.

Table 3 shows the results of each evaluation.

Edge bubble durability Rework 85℃ 500h HS 300
cycle 85℃ 500h 60℃/95% RH, 500h HS 300 cycles Early After heating Adhesion
(N/25mm) real
Rework Adhesion
(N/25mm) real
Rework Example 1 ○ ○ ○ ○ ◎ 1.3 ◎ 3.3 ○ Example 2 ◎ ◎ ◎ ○ ◎ 1.6 ◎ 2.9 ◎ Example 3 ◎ ◎ ◎ ◎ ◎ 1.8 ◎ 3.5 ○ Example 4 ○ ○ ◎ ◎ ◎ 3.5 ○ 4.5 △ Example 5 ◎ ○ ◎ ◎ ◎ 3.1 ○ 4.2 △ Example 6 ◎ ◎ ◎ ◎ ◎ 3.9 ○ 4.9 △ Example 7 ◎ ◎ ○ ◎ ◎ 1.9 ◎ 2.5 ◎ Example 8 ◎ ◎ ○ ◎ ◎ 1.6 ◎ 2.6 ◎ Example 9 ◎ ◎ ◎ ◎ ◎ 2.1 ◎ 2.8 ◎ Example 10 ◎ ◎ ◎ ◎ ◎ 2.8 ◎ 3.2 ○ Example 11 ◎ ◎ ◎ ◎ ◎ 3.5 ○ 4.6 △ Example 12 ◎ ◎ ◎ ◎ ◎ 2.5 ◎ 2.9 ◎ Example 13 ◎ ◎ ◎ ◎ ◎ 2.2 ◎ 2.4 ◎ Example 14 ◎ ◎ ◎ ◎ ◎ 3.1 ○ 4.2 △ Example 15 ◎ ◎ ◎ ◎ ◎ 2.7 ◎ 2.8 ◎ Example 16 ◎ ◎ ◎ ◎ ◎ 2.4 ◎ 2.8 ◎ Example 17 ◎ ◎ ◎ ◎ ◎ 3.6 ○ 4.6 △ Example 18 ◎ ◎ ◎ ◎ ◎ 2.3 ◎ 2.6 ◎ Comparative Example 1 Ⅹ Ⅹ Ⅹ ○ Ⅹ 2.5 ◎ 3.5 ○ Comparative Example 2 △ Ⅹ Ⅹ ○ Ⅹ 2.8 ◎ 4.2 △ Comparative Example 3 △ Ⅹ Ⅹ ○ Ⅹ 2.7 ◎ 4.1 △ Comparative Example 4 Ⅹ Ⅹ ○ ○ ○ 3.5 ○ 5.5 Ⅹ Comparative Example 5 △ Ⅹ ○ ○ ○ 3.8 ○ 6.4 Ⅹ Comparative Example 6 △ Ⅹ ○ ○ ○ 3.5 ○ 6.1 Ⅹ Comparative Example 7 △ Ⅹ Ⅹ ○ Ⅹ 1.5 ◎ 1.8 ◎ Comparative Example 8 △ Ⅹ ○ ○ ○ 1.8 ◎ 2.6 ◎

As is clear from Table 3, the single-sided protective polarizer with pressure-sensitive adhesive layer prepared using the pressure-sensitive adhesive for optical films of the present inventions of Examples 1 to 18 was subjected to harsh environments (high temperature, high humidity, and thermal shock). It has been found that durability (especially, suppression of bubbles generated at the edge of the polarizing plate and suppression of peeling of the polarizing plate) can be improved, and furthermore, reworkability (processability) is also excellent.

On the other hand, in the evaluation of the bubble at the edge after the thermal shock (HS) test, the single-sided protective polarizing plate with the pressure-sensitive adhesive layer of Comparative Examples 1 to 8 had a significant number of bubbles at the edge, and found that there was a practical problem. . In addition, it was found that the evaluation of either durability (suppression of bubbles generated at the edge of the polarizing plate and peeling of the polarizing plate) and reworkability (processability) was poor (× evaluation) or low (△ evaluation).

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (19)

It is a pressure-sensitive adhesive for an optical film 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) is an optical film pressure-sensitive adhesive comprising at least one compound selected from the group consisting of compounds represented by the following general formula 1 to general formula 4 having an isocyanurate skeleton :
(Formula 1)

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.
(Formula 2)

The general formula double,
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 , Y ² 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.
(Formula 3)

The general formula triple,
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 , Y ² is a group represented by the following formula 5,
n and m are each independently an integer of 1 to 8,
a and b are each independently an integer of 0 or more and 3 or less.
(Formula 4)

The general formula quadruple,
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 , Y ³ are groups represented by the following formula 5,
n and m are each independently an integer of 1 to 8,
a and b are each independently an integer of 0 or more and 3 or less.
(Formula 5)

In Equation 5, * denotes a part connected to another atom (adjacent atom).
The pressure-sensitive adhesive for an optical film 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 1a to 4a.
(Formula 1a)

(Formula 2a)

(Formula 3a)

(Formula 4a)

The pressure-sensitive adhesive for an optical film according to claim 1 or 2, wherein the polymer component (A) having a hydroxyl group is a (meth)acrylic acid ester copolymer (A1).
The polymer component (A) having a hydroxyl group according to claim 1 or 2,
A pressure-sensitive adhesive for an optical film, further comprising at least one component (C) selected from a crosslinking agent and a curing agent.
The pressure-sensitive adhesive for an optical film according to claim 1 or 2, further comprising a silane coupling agent (D) containing no isocyanate group.
The (meth)acrylic acid ester copolymer (A1) according to claim 3, wherein
(a1) a structural unit derived from an alkyl (meth)acrylate monomer, and
(a2) at least one structural unit selected from the group consisting of a structural unit derived from a (meth)acrylate monomer having a hydroxyl group and a structural unit derived from a monomer having a (a3)carboxyl group,
Adhesive for an optical film, characterized in that it comprises a.
The pressure-sensitive adhesive for an optical film according to claim 1, wherein the (meth)acrylic acid ester copolymer (A1) has a weight average molecular weight of 500,000 to 2 million.
7. The pressure-sensitive adhesive for an optical film according to claim 6, wherein the (a1) component has 1 to 18 carbon atoms in the alkyl.
The method according to claim 4, characterized in that at least one component (C) selected from the crosslinking agent and curing agent is contained in an amount of 0.001 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer component (A) having the hydroxyl group. Adhesive for optical film to be said.
The crosslinking agent and the curing agent according to claim 4, wherein at least one component (C) selected from the group consisting of isocyanate compounds, carbodiimide compounds, oxazoline compounds, epoxy compounds, polyfunctional acrylic acid ester monomers and peroxides A pressure-sensitive adhesive for an optical film comprising at least one.
The optical film according to claim 5, wherein the silane coupling agent (D) containing no isocyanate group is contained in an amount of 0.001 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the polymer component (A) having the hydroxyl group. adhesive.
An adhesive layer for an optical film, characterized in that it is formed of the adhesive for an optical film of claim 1 or 2.
The adhesive layer for an optical film of claim 12,
An optical member comprising a first optical film formed on one side of the pressure-sensitive adhesive layer.
The adhesive layer for an optical film of claim 12,
A first optical film formed on one surface of the pressure-sensitive adhesive layer,
An optical member comprising a glass or a second optical film formed on the other surface of the pressure-sensitive adhesive layer.
The optical member according to claim 13 or 14, further comprising at least one self-adhesive treatment layer between the first optical film and the pressure-sensitive adhesive layer for the optical film.
16. The method according to claim 15, between the first optical film and the pressure-sensitive adhesive layer for the optical film, in order from the first optical film side, the first self-adhesive treatment layer, the second self-adhesive treatment layer Optical member comprising a.
An image display apparatus characterized by using at least one of the optical members of claim 13 or 14.
A method for manufacturing 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 subjecting it to heat treatment for crosslinking.
The method for manufacturing the pressure-sensitive adhesive layer for an optical film according to claim 18, wherein the temperature of the heat treatment is 80°C or higher and 120°C or lower.