KR20200057642A - Adhesive composition for protective film of optical member and protective film of optical member - Google Patents

Abstract

The present invention relates to an adhesive composition for a protective film of an optical member, and to a protective film of an optical member. In particular, the adhesive composition comprises: a (meth)acrylic copolymer (A) comprising a constitutive unit derived from n-BA and a constitutive unit derived from a hydroxyl group-containing monomer, and having a Tg of -40°C or less and a Mw of 200,000 to 2,000,000; a (meth)acrylic copolymer (B) comprising a constitutive unit derived from n-BMA and a constitutive unit derived from a hydroxyl group-containing monomer, and having a Tg from 0-45°C and a Mw of 10,000 to 200,000; and an isocyanate-based crosslinker, wherein a (meth)acrylic copolymer (B) content is 1-70 parts by weight with respect to 100 parts by weight of the (meth)acrylic copolymer (A).

Description

Adhesive composition for optical member protective film and optical member protective film {ADHESIVE COMPOSITION FOR PROTECTIVE FILM OF OPTICAL MEMBER AND PROTECTIVE FILM OF OPTICAL MEMBER}

The present invention relates to an adhesive composition for an optical member protective film and an optical member protective film.

In order to protect the surface of various articles, a protective film having an adhesive layer is widely used. In particular, protective films are used in various optical members represented by polarizing plates.

For example, Japanese Unexamined Patent Publication No. 2005-146151 discloses (A) a (meth) acrylic polymer having a glass transition temperature of at least -40 ° C or less by copolymerizing at least a (meth) acrylic acid alkyl ester and a functional group-containing monomer, (B) (meta) A crosslinking agent containing a (meth) acrylic polymer and a (C) crosslinking agent having a glass transition temperature of 80 deg. Disclosed is a pressure-sensitive adhesive for a protective sheet formed by crosslinking a composition so that the gel fraction is 80% or more.

In addition, Japanese Unexamined Patent Publication No. 2013-216769 discloses (meth) acrylic polymer having 100 parts by mass of polymer (A) having a glass transition temperature of less than 0 ° C, and having a weight average molecular weight of 1000 or more and less than 50000 and a glass transition temperature of 30 to 300 ° C. (B) An adhesive composition comprising an organopolysiloxane compound (C) having a specific structure having 0.05 to 3 parts by mass and a polyoxyalkylene chain is disclosed.

In addition, Japanese Unexamined Patent Publication No. 2017-128636 discloses a (meth) acrylic polymer having a hydroxyl group and having an acid value of 0 mgKOH / g or more and less than 16 mgKOH / g, and an alkylene oxide chain containing an acid value of 0.1 mgKOH / g or more and 40 mgKOH / g or less (meth) acrylic oligomer. And a pressure-sensitive adhesive composition comprising a polyether-modified silicone having a reactive group, a crosslinking agent, and an ionic compound.

The pressure-sensitive adhesive composition used in the protective film used for the optical member (hereinafter also referred to as "the optical member protective film pressure-sensitive adhesive composition") is affixed to the surface of the optical member and then peeled off from the optical member while protection is required, It is required that a pressure-sensitive adhesive layer capable of efficiently peeling from the optical member is formed at a stage in which defects such as misalignment are unlikely to occur and protection is unnecessary. Here, the pressure-sensitive adhesive layer, which is unlikely to cause defects such as peeling and misalignment from the optical member, is evaluated by the adhesive force (so-called low-speed peeling force) measured when the protective film is peeled from the optical member at a low speed (0.3 m / min). Can be. In addition, the pressure-sensitive adhesive layer that can be efficiently peeled from the optical member can be evaluated by the adhesive force (so-called high-speed peeling force) measured when the protective film is peeled from the optical member at high speed (30 m / min).

By the way, when peeling off a protective film from an optical member, the phenomenon called zipping (hereinafter also referred to as a `` jipping phenomenon '') that peels off without a soft peeling may occur. When the jing phenomenon occurs, a gold-like defect may be confirmed on the surface of the optical member after peeling off the protective film. Therefore, it is also required that the pressure-sensitive adhesive layer capable of suppressing the jing phenomenon is formed in the pressure-sensitive adhesive composition for an optical member protective film.

Furthermore, the pressure-sensitive adhesive composition for an optical member protective film is required to be able to form a highly transparent pressure-sensitive adhesive layer so that the appearance of the optical member can be confirmed while the protective film is stuck.

However, when controlling the low-speed peeling force and the high-speed peeling force of the pressure-sensitive adhesive layer provided by the protective film, it is difficult to adjust the balance between the low-speed peeling force and the high-speed peeling force because both exhibit the same behavior.

In addition, in recent years, from the viewpoint of further improving workability, there is a tendency that the peeling speed of the protective film from the optical member becomes higher. In addition, with the thinning of the optical member, the surface defects of the optical member tend to be more likely to occur due to the zipping phenomenon at the time of peeling of the protective film. It is said that the jing phenomenon occurs due to the strength and weakness of the adhesive layer. In general, since the adhesive force of the pressure-sensitive adhesive layer tends to increase as the peeling speed increases, the jing phenomenon tends to occur when the protective film is peeled from the optical member at high speed.

Therefore, an adhesive composition for an optical member protective film capable of forming a pressure-sensitive adhesive layer having both a good balance of low-speed peeling force and high-speed peeling force, that is difficult to occur in the case of peeling at high speed, and excellent transparency is achieved. It was difficult to do.

The problem to be solved by the present invention is that the balance between the low-speed peeling force and the high-speed peeling force is good, and the jeeping phenomenon that may occur when peeling at a high speed is sufficiently suppressed, and an optical member capable of forming an adhesive layer having excellent transparency It is to provide an adhesive composition for a protective film and a protective film for an optical member.

Specific means for solving the problem include the following aspects.

<1> A structural unit derived from n-butyl acrylate and a structural unit derived from a monomer having a hydroxyl group, having a glass transition temperature of -40 ° C or less, and a weight average molecular weight of 200,000 to 2,000,000 Phosphorous (meth) acrylic copolymer (A),

It includes a structural unit derived from n-butyl methacrylate and a structural unit derived from a monomer having a hydroxyl group, and has a glass transition temperature of 0 ° C or more and 45 ° C or less, and a weight average molecular weight of 10,000 or more and 200,000 or less. (Meth) acrylic copolymer (B) that is in the range of,

It contains an isocyanate-based crosslinking agent,

The adhesive composition for optical member protective films whose content of the said (meth) acrylic-type copolymer (B) is 1 mass part or more and 70 mass parts or less with respect to 100 mass parts of said (meth) acrylic-type copolymer (A).

<2> The adhesive composition for an optical member protective film according to <1>, wherein the glass transition temperature of the (meth) acrylic copolymer (A) is in the range of -70 ° C to -40 ° C.

<3> The content rate of the constituent units derived from the n-butyl methacrylate in the (meth) acrylic copolymer (B) is 50% by mass or more with respect to the total constituent units of the (meth) acrylic copolymer (B). , <1> or <2>, the pressure-sensitive adhesive composition for an optical member protective film.

<4> The content ratio of the constituent units derived from the n-butylacrylate in the (meth) acrylic copolymer (A) is 50% by mass or more with respect to the total constituent units of the (meth) acrylic copolymer (A), The pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <3>.

<5> The content ratio of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (A) is 0.7% by mass or more and 15% by mass relative to the total structural units of the (meth) acrylic copolymer (A). The adhesive composition for optical member protective films as described in any one of <1>-<4> which is a range of% or less.

<6> The content ratio of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B) is 0.7 mass% or more and 15 mass% based on the total structural units of the (meth) acrylic copolymer (B). The adhesive composition for optical member protective films as described in any one of <1>-<5> which is a range of% or less.

<7> <1> to <6>, wherein the content of the (meth) acrylic copolymer (B) is in a range of 3 parts by mass to 60 parts by mass relative to 100 parts by mass of the (meth) acrylic copolymer (A) The adhesive composition for optical member protective films described in any one of the above.

<8> The adhesive composition for an optical member protective film according to any one of <1> to <7>, wherein the weight average molecular weight of the (meth) acrylic copolymer (B) is in the range of 10,000 to 150,000.

<9> The pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <8>, wherein the isocyanate-based crosslinking agent is hexamethylene diisocyanate.

<10> Optical member protection provided with the base material and the adhesive layer provided on the said base material, and also formed with the adhesive composition for optical member protective films in any one of <1>-<9> film.

According to the present invention, the balance between the low-speed peeling force and the high-speed peeling force is good, and the zipping phenomenon that can occur when peeling at a high speed is sufficiently suppressed, and the adhesive for an optical member protective film capable of forming an adhesive layer excellent in transparency A composition and an optical member protective film are provided.

Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments at all, and can be carried out with appropriate changes within the scope of the object of the present invention.

In the present specification, a numerical range indicated by using “~” means a range including numerical values described before and after “~” as minimum and maximum values, respectively.

In the numerical ranges described in stages in the present specification, the upper or lower limit values described in a certain numerical range may be substituted with the upper or lower limit values of the numerical ranges of other stepwise descriptions. In addition, in the numerical range described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be substituted with the value shown in the Example.

Combinations of two or more preferred aspects herein are more preferred aspects.

In the present specification, the amount of each component means a total amount of a plurality of substances unless otherwise specified, when there are multiple kinds of substances corresponding to each component.

In the present specification, the "(meth) acrylic copolymer" means that the content rate of the structural unit derived from the monomer having a (meth) acryloyl group is 50% by mass or more of the total structural units (i.e., the total structural units of the (meth) acrylic polymer). Means a copolymer.

In this specification, "(meth) acrylic" is a term that includes both "acrylic" and "methacryl", and "(meth) acrylate" is a term that includes both "acrylate" and "methacrylate". And "(meth) acryloyl" is a term including both "acryloyl" and "methacryloyl".

In this specification, "n-" means normal, "i-" means iso, "s-" means secondary, and "t-" means tertiary.

In the present specification, the "adhesive composition" means a liquid or paste-like substance before the crosslinking reaction is completed.

In the present specification, the “adhesive layer” means a film made of a material after the crosslinking reaction in the pressure-sensitive adhesive composition is completed.

In the present specification, the term "adhered body" refers to the optical member.

As used herein, "low-speed peeling force" refers to the adhesive force measured when the protective film adhered to the adherend is peeled 180 ° at a low speed (ie, 0.3 m / min) in the longitudinal direction of the protective film from the adherend. In addition, the detailed measuring method is as showing in the Example mentioned later.

In the present specification, "appropriate low-speed peeling force" means an adhesive strength of a strength that is difficult to cause defects such as peeling and displacement from an adherend.

In the present specification, "high-speed peeling force" means the adhesive force measured when the protective film adhered to the adherend is peeled 180 ° at high speed (ie, 30 m / min) in the longitudinal direction of the protective film from the adherend. In addition, the detailed measuring method is as showing in the Example mentioned later.

In the present specification, "appropriate high-speed peeling force" means an adhesive force having a strength sufficient to be peeled off efficiently from an adherend.

In the present specification, the term “adhesive layer having a good balance of low-speed peeling force and high-speed peeling force” is unlikely to cause defects such as peeling or misalignment from the adherend, and also provides an adhesive strength with a strength sufficient to effectively peel from the adherend. It means the adhesive layer to have.

In this specification, the "optical member protective film" is also referred to simply as a "protective film."

[Adhesive composition for optical member protective film]

The pressure-sensitive adhesive composition for an optical member protective film of the present invention (hereinafter also simply referred to as "adhesive composition") includes a structural unit derived from n-butylacrylate and a structural unit derived from a monomer having a hydroxyl group, and has a glass transition temperature. (Meth) acrylic copolymer (A) (hereinafter also referred to as “specific (meth) acrylic copolymer (A)”) having a temperature average molecular weight of -40 ° C. or less, and a weight average molecular weight of 200,000 to 2,000,000, and n -Containing units derived from butyl methacrylate and constituent units derived from a monomer having a hydroxyl group, the glass transition temperature is in the range of 0 ° C or more and 45 ° C or less, and the weight average molecular weight is 10,000 or more and 200,000 or less. The content of the specific (meth) acrylic copolymer (B), including the (meth) acrylic copolymer (B) in the range (hereinafter also referred to as "specific (meth) acrylic copolymer (B)") and an isocyanate-based crosslinking agent It is the range of 1 mass part or more and 70 mass parts or less with respect to 100 mass parts of this specific (meth) acrylic-type copolymer (A).

According to the pressure-sensitive adhesive composition of the present invention, the balance between the low-speed peeling force and the high-speed peeling force is good, and the jinging phenomenon that may occur when peeling at a high speed is sufficiently suppressed, and an adhesive layer excellent in transparency can be formed.

Although it is not clear why the pressure-sensitive adhesive composition of the present invention can exhibit such an effect, the present inventors speculate as follows. However, the following speculation is not limited to interpret the pressure-sensitive adhesive composition of the present invention, but is described as an example.

The specific (meth) acrylic copolymer (B) contained in the pressure-sensitive adhesive composition of the present invention has a glass transition temperature of 0 ° C or higher, and a weight average molecular weight of 10,000 to 200,000 or less. Moreover, content of the specific (meth) acrylic-type copolymer (B) in the adhesive composition of this invention is 1 mass part or more and 70 mass parts or less with respect to 100 mass parts of specific (meth) acrylic-type copolymers (A). For this reason, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, it is considered that the specific (meth) acrylic copolymer (B) is appropriately localized near the surface (so-called interface with the adherend). In the pressure-sensitive adhesive layer, if the specific (meth) acrylic copolymer (B) is appropriately localized near the interface with the adherend, it is assumed that the pressure-sensitive adhesive layer exhibits an appropriate high-speed peeling force because the wetness of the pressure-sensitive adhesive layer does not become excessive. do. In addition, since the glass transition temperature of the specific (meth) acrylic copolymer (B) is 45 ° C. or less, it is considered that the wetness of the pressure-sensitive adhesive layer to the adherend becomes suitable. Therefore, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, it is presumed that the jinging phenomenon due to insufficient wettability of the pressure-sensitive adhesive layer to the adherend is suppressed.

The specific (meth) acrylic copolymer (A) contained in the pressure-sensitive adhesive composition of the present invention has a glass transition temperature of -40 ° C or less, and a weight average molecular weight of 200,000 to 2,000,000. Therefore, it is estimated that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention exhibits a suitable low-speed peeling force. In addition, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, it is presumed that the zip phenomenon that can occur when peeling at a high speed is sufficiently suppressed.

The pressure-sensitive adhesive composition of the present invention includes a specific (meth) acrylic copolymer (A) having a different monomer composition and a specific (meth) acrylic copolymer (B).

In general, in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition containing two or more types of copolymers having different monomer compositions, a problem of low transparency (so-called haze increase) tends to occur.

The specific (meth) acrylic copolymer (A) contained in the pressure-sensitive adhesive composition of the present invention contains a structural unit derived from n-butyl acrylate, and the specific (meth) acrylic copolymer (B) is n-butyl methacryl It contains the structural unit derived from a rate. Since the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) both contain constituent units derived from a monomer having an n-butyl group, the compatibility tends to be improved. Therefore, it is estimated that the adhesive layer formed from the adhesive composition of this invention is excellent in transparency.

Since the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) contained in the pressure-sensitive adhesive composition of the present invention both contain structural units derived from monomers having hydroxyl groups, they are appropriately crosslinked with isocyanate-based crosslinkers. Reacts. Therefore, it is estimated that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention has a good balance between low-speed peeling power and high-speed peeling power. In addition, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, it is presumed that the zip phenomenon that can occur when peeling at a high speed is sufficiently suppressed.

In contrast to the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive for a protective sheet described in JP 2005-146151 A includes two types of (meth) acrylic polymers, but the glass transition of (meth) acrylic polymer of component (B) Since the temperature (Tg) is 80 ° C or higher, the pressure-sensitive adhesive layer formed lacks wetness to the adherend, and, for example, at a high-speed peeling at a peeling speed of 30 m / min, the jing phenomenon is not sufficiently suppressed.

The pressure-sensitive adhesive composition described in Japanese Patent Application Laid-Open No. 2013-216769 contains two types of copolymers, but the glass transition temperature (Tg) of (meth) acrylic polymer (B) is 59 ° C or higher, and therefore, Japanese Patent Publication No. 2005-146151 The pressure-sensitive adhesive layer formed in the same way as the pressure-sensitive adhesive for a protective sheet described in the publication is insufficient for wetness to the adherend, and, for example, at a high-speed peeling at a peeling speed of 30 m / min, the jing phenomenon is not sufficiently suppressed. In addition, the two types of copolymers included in the pressure-sensitive adhesive composition disclosed in Japanese Patent Laid-Open No. 2013-216769 have insufficient monomer transparency, and thus the transparency of the pressure-sensitive adhesive layer is not sufficient.

The pressure-sensitive adhesive composition described in Japanese Patent Laid-Open No. 2017-128636 contains two types of (meth) acrylic copolymers, but is formed because an alkylene oxide chain is contained in (meth) acrylic copolymers corresponding to oligomers. It is thought that the wetting of the layer to the adherend is too accelerated and the high-speed peeling force is excessively increased. Therefore, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition described in Japanese Patent Laid-Open No. 2017-128636 has a poor balance between low-speed peeling power and high-speed peeling power (for example, see Comparative Example 16 described later).

Hereinafter, in this specification, "specific (meth) acrylic copolymer (A) and specific (meth) acrylic copolymer (B)" are collectively referred to as "specific (meth) acrylic copolymer".

[Specific (meth) acrylic copolymer (A)]

The pressure-sensitive adhesive composition of the present invention comprises a structural unit derived from n-butylacrylate and a structural unit derived from a monomer having a hydroxyl group, the glass transition temperature is -40 ° C or less, and the weight average molecular weight is 200,000 or more and 2 million. It includes (meth) acrylic-type copolymer (A) (namely, specific (meth) acrylic-type copolymer (A)) which is the following range.

<Constituent unit derived from n-butyl acrylate>

The specific (meth) acrylic copolymer (A) contains constituent units derived from n-butyl acrylate.

In the present specification, "the structural unit derived from n-butyl acrylate" means a structural unit formed by addition polymerization of n-butyl acrylate.

The content rate (so-called content ratio; hereinafter the same) of the constituent unit derived from n-butylacrylate in the specific (meth) acrylic copolymer (A) is not particularly limited.

It is preferable that the content rate of the structural unit derived from n-butylacrylate in the specific (meth) acrylic copolymer (A) is 40% by mass or more with respect to the total structural units of the specific (meth) acrylic copolymer (A), for example. And more preferably 45% by mass or more, and even more preferably 50% by mass or more.

If the content rate of the constituent unit derived from n-butylacrylate in the specific (meth) acrylic copolymer (A) is 40% by mass or more relative to the total constituent units of the specific (meth) acrylic copolymer (A), the (meth) acrylic system Since the compatibility with the copolymer (B) becomes better, there is a tendency that a pressure-sensitive adhesive layer in which haze is further suppressed can be formed.

In addition, the content rate of the constitutional unit derived from n-butylacrylate in the specific (meth) acrylic copolymer (A) is, for example, 70 mass% or less with respect to the total constitutional unit of the specific (meth) acrylic copolymer (A). It is preferred.

If the content rate of the constituent units derived from n-butylacrylate in the specific (meth) acrylic copolymer (A) is 70% by mass or less with respect to the total constituent units of the specific (meth) acrylic copolymer (A), the There is a tendency that an adhesive layer having a better balance of high-speed peeling power can be formed.

<Constituent unit derived from a monomer having a hydroxyl group>

Certain (meth) acrylic copolymers (A) include structural units derived from monomers having hydroxyl groups.

In the present specification, "a structural unit derived from a monomer having a hydroxyl group" means a structural unit formed by addition polymerization of a monomer having a hydroxyl group.

The type of the monomer having a hydroxyl group is not particularly limited.

As a specific example of the monomer which has a hydroxyl group, 2-hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate , 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 3-methyl- 3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-hydroxybutyl (meth) acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4 -Hydroxymethyl (meth) acrylates such as trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, and N-hydroxyethyl (meth) acrylamide, And 1,4-cyclohexanedimethanol monoacrylate, dicaprolactone-2-acryloyloxy-ethyl ether, and the like.

Among these, as the monomer having a hydroxyl group, for example, hydroxyalkyl (meth) acrylate is preferred from the viewpoint of good copolymerization with n-butyl acrylate.

As the hydroxyalkyl (meth) acrylate, for example, from the viewpoint of good compatibility with n-butyl acrylate and copolymerizability and good reactivity with an isocyanate-based crosslinking agent, a hydroxyalkyl group having 1 to 5 carbon atoms. The hydroxyalkyl (meth) acrylate to have is preferable, and the hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable.

The specific (meth) acrylic copolymer (A) may contain only one type of structural unit derived from a monomer having a hydroxyl group, or may contain two or more types.

Although the content rate of the structural unit derived from the monomer which has a hydroxyl group in a specific (meth) acrylic-type copolymer (A) is not specifically limited, For example, 0.1 mass with respect to all the structural units of a specific (meth) acrylic-type copolymer (A) It is preferably in the range of% to 20% by mass, more preferably in the range of 0.7% to 15% by mass, and more preferably in the range of 1% by mass to 10% by mass.

It is specific (meth) acrylic that the content ratio of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) is 0.1% by mass or more with respect to the total structural units of the specific (meth) acrylic copolymer (A) It means that the copolymer (A) actively contains a structural unit derived from a monomer having a hydroxyl group.

When the content rate of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) is 20% by mass or less with respect to the total structural unit of the specific (meth) acrylic copolymer (A), when peeling at high speed There is a tendency to be able to form a pressure-sensitive adhesive layer is more sufficiently suppressed the jinging phenomenon that can occur in the. In addition, there is a tendency to form an adhesive layer having better transparency.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer different from n-butyl acrylate>

The specific (meth) acrylic copolymer (A) is a structural unit derived from a (meth) acrylic acid alkylester monomer different from n-butylacrylate (hereinafter also referred to as another (meth) acrylic acid alkylester monomer (a)). It is preferred to include.

The structural unit derived from another (meth) acrylic acid alkyl ester monomer (a) contributes to the adjustment of the adhesive force of the pressure-sensitive adhesive layer.

In the present specification, "the structural unit derived from another (meth) acrylic acid alkylester monomer (a)" means a structural unit formed by addition polymerization of another (meth) acrylic acid alkylester monomer (a).

As other (meth) acrylic acid alkylester monomer (a), if it is a (meth) acrylic acid alkylester monomer different from n-butylacrylate, the kind is not specifically limited.

As another (meth) acrylic acid alkylester monomer (a), an unsubstituted (meth) acrylic acid alkylester monomer is preferable.

The alkyl group of the other (meth) acrylic acid alkyl ester monomer (a) may be linear, branched or cyclic.

Further, the number of carbon atoms of the alkyl group is preferably 1 to 18, and more preferably 1 to 12, from the viewpoint of adhesion to the adherend of the pressure-sensitive adhesive layer to be formed and adhesion of the protective film to the base material.

As other (meth) acrylic acid alkyl ester monomer (a), methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl methacrylate, i-butyl (meth) acrylate, s-butyl (meth) acrylate , t-butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (Meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, iso And carbonyl (meth) acrylates.

Among these, other (meth) acrylic acid alkyl ester monomers (a), for example, 2-ethylhexyl from the viewpoint of easy adjustment of the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) to -40 ° C or less. Acrylate (2EHA) is preferred.

When a specific (meth) acrylic-type copolymer (A) contains the structural unit derived from another (meth) acrylic acid alkylester monomer (a), the structural unit derived from another (meth) acrylic acid alkylester monomer (a) is 1 The species may be included, or two or more may be included.

When a specific (meth) acrylic copolymer (A) contains a structural unit derived from another (meth) acrylic acid alkylester monomer (a), another (meth) acrylic acid alkyl in a specific (meth) acrylic copolymer (A) The content rate of the structural unit derived from the ester monomer (a) is, for example, preferably in the range of 10% by mass or more and 59.9% by mass or less with respect to all the structural units of the specific (meth) acrylic copolymer (A), and 15% by mass It is more preferably in the range of 50% by mass or more, and more preferably in the range of 20% by mass or more and 40% by mass or less.

<Constituent unit derived from a monomer having a carboxyl group>

The specific (meth) acrylic copolymer (A) may contain a structural unit derived from a monomer having a carboxy group.

When a specific (meth) acrylic copolymer (A) contains a structural unit derived from a monomer having a carboxy group, the high-speed peeling force of the pressure-sensitive adhesive layer formed decreases, and the balance between the low-speed peeling force and the high-speed peeling force tends to be better. .

In the present specification, "the structural unit derived from a monomer having a carboxyl group" means a structural unit formed by addition polymerization of a monomer having a carboxyl group.

The type of the monomer having a carboxyl group is not particularly limited.

Specific examples of the monomer having a carboxy group include acrylic acid (AA), methacrylic acid (MAA), crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, ω-carboxy-polycaprolactone mono (meth) acrylic. And rate (for example, ω-carboxy-polycaprolactone (n ≒ 2) monoacrylate), succinic acid ester (for example, 2-acryloyloxyethyl-pumponic acid) and the like.

Among these, as the monomer having a carboxy group, acrylic acid (AA) is preferred from the viewpoint of good reactivity with an isocyanate-based crosslinking agent, for example.

When a specific (meth) acrylic-type copolymer (A) contains the structural unit derived from the monomer which has a carboxy group, it may contain only 1 type and may contain 2 or more structural units derived from the monomer which has a carboxy group.

When the specific (meth) acrylic copolymer (A) contains a structural unit derived from a monomer having a carboxy group, the content rate of the structural unit derived from a monomer having a carboxy group in the specific (meth) acrylic copolymer (A) is specific It is preferable that it is the range of 0.1 mass% or more and 5 mass% or less with respect to the whole structural unit of (meth) acrylic-type copolymer (A), It is more preferable that it is the range of 0.3 mass% or more and 3 mass% or less, More preferably, it is 0.5 mass% or more. It is more preferable that it is 1.5 mass% or less of range.

The content of the constituent unit derived from the monomer having a carboxyl group in the specific (meth) acrylic copolymer (A) is 0.1 mass% or more with respect to the total constituent units of the specific (meth) acrylic copolymer (A). There is a tendency that the high-speed peeling force is lowered more.

When the content rate of the structural unit derived from the monomer having a carboxyl group in the specific (meth) acrylic copolymer (A) is 5% by mass or less with respect to the total structural unit of the specific (meth) acrylic copolymer (A), when peeling at high speed There is a tendency to be able to form a pressure-sensitive adhesive layer is more sufficiently suppressed the jinging phenomenon that can occur in the.

<Other components>

The specific (meth) acrylic copolymer (A) is derived from a monomer having a structural unit and a hydroxyl group derived from the above-described structural unit, that is, an essential structural unit, within the range in which the effects of the present invention are exhibited. Constituent units other than the structural units derived from other (meth) acrylic acid alkyl ester monomers (a) and structural units derived from monomers having a carboxyl group (so-called other structural units) may be included. .

The monomer constituting the other constitutional units is not particularly limited as long as it can be copolymerized with the monomer constituting the constitutional units described above.

As the monomers constituting the other structural units, for example, (meth) acrylate, methoxyethyl (meth) acrylate and ethoxy having a cyclic group represented by benzyl (meth) acrylate and phenoxyethyl (meth) acrylate Aromatic monovinyl, acrylonitrile represented by alkoxyalkyl (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and vinyltoluene represented by ethyl (meth) acrylate And vinyl esters represented by vinyl cyanide, vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatic acid represented by methacrylonitrile. Moreover, various derivatives of these monomers are mentioned.

However, when the specific (meth) acrylic copolymer (A) contains a structural unit derived from (meth) acrylate having a cyclic group, (meth) acrylic having a cyclic group in a specific (meth) acrylic copolymer (A) The content rate of the structural unit derived from the rate is, for example, from the viewpoint of transparency of the pressure-sensitive adhesive layer to be formed, it is preferably 10% by mass or less, and 5% by mass or less with respect to all the structural units of the specific (meth) acrylic copolymer (A) More preferably, it is more preferably 1% by mass or less, and the specific (meth) acrylic copolymer (A) does not contain a structural unit derived from (meth) acrylate having a cyclic group, that is, it is particularly 0% by mass. desirable.

<< The glass transition temperature of a specific (meth) acrylic copolymer (A) >>

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is -40 ° C or less, preferably -50 ° C or less, more preferably -55 ° C or less, and even more preferably -60 ° C or less.

When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is -40 ° C or less, the pressure-sensitive adhesive layer having a good balance of low-speed peeling power and high-speed peeling power without forming too high a high-speed peeling force can be formed. In addition, it is possible to form the pressure-sensitive adhesive layer sufficiently suppressed the jinging phenomenon that may occur when peeling at a high speed.

The lower limit of the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is not particularly limited, and for example, -70 ° C or higher is preferable from the viewpoint of adhesion to the adherend.

The glass transition temperature (Tg) of a specific (meth) acrylic copolymer (A) is converted from the absolute temperature (unit: K; same as below) obtained by calculation from the following formula 1 to the temperature in degrees Celsius (unit: ℃; same as below). It is one value.

1 / Tg = m1 / Tg1 + m2 / Tg2 +… + m (k-1) / Tg (k-1) + mk / Tgk (Equation 1)

In formula 1, Tg1, Tg2,… , Tg (k-1) and Tgk each indicate a glass transition temperature (Tg) expressed as an absolute temperature (K) when each monomer constituting a specific (meth) acrylic copolymer (A) is a homopolymer. m1, m2,… , m (k-1) and mk indicate the molar fraction of each monomer constituting a specific (meth) acrylic copolymer (A), and m1 + m2 +… + m (k-1) + mk = 1.

Also, by subtracting 273 from the absolute temperature (K), the absolute temperature (K) can be converted to the temperature in degrees Celsius (℃), and by adding 273 to the temperature in degrees Celsius (℃), the temperature in degrees Celsius (℃) is added to the absolute temperature (K). Can be converted to

In the present specification, "glass transition temperature (Tg) expressed as absolute temperature (K) when used as a homopolymer" is a glass transition temperature (Tg) expressed as an absolute temperature (K) of a homopolymer prepared by polymerizing the monomer alone. Says

The glass transition temperature (Tg) of the homopolymer was measured in a nitrogen stream using a differential scanning calorimeter (DSC) [Model No .: EXSTAR6000, manufactured by Seiko Instruments Co., Ltd.] under a condition of 10 mg of sample and a rate of temperature increase of 10 ° C / min. The inflection point of the obtained DSC curve was taken as the glass transition temperature (Tg) of the homopolymer.

As for the representative monomer, "the glass transition temperature (Tg) expressed in degrees Celsius (° C) when used as a homopolymer" is 2-ethylhexyl acrylate (2EHA) at -76 ° C and 2-ethylhexyl methacrylate (2EHMA). -10 ℃, n-butyl acrylate (n-BA) is -57 ℃, n-butyl methacrylate is 21 ℃, t-butyl acrylate (t-BA) is 41 ℃, t-butyl methacrylate ( t-BMA) is 107 ° C, i-butyl methacrylate (i-BMA) is 48 ° C, methyl acrylate (MA) is 5 ° C, methyl methacrylate (MMA) is 103 ° C, isobornyl methacrylate ( IBXMA) is 155 ℃, isobornyl acrylate (IBXA) is 96 ℃, cyclohexyl methacrylate (CHMA) is 56 ℃, ethyl acrylate (EA) is -27 ℃, ethyl methacrylate (EMA) is 42 ℃ , Methacrylic acid is 185 ° C, 4-hydroxybutyl acrylate (4HBA) is -39 ° C, 2-hydroxyethyl acrylate (2HEA) is -15 ° C, and 2-hydroxyethyl methacrylate (2HEMA) is 55 ℃, acrylic acid (AA) 163 ℃, isooctyl acrylate (i-OA) -75 ℃, dimethylaminoethyl methacrylate (DM) 18 ℃, ω-carboxy-polycaprolactone (n ≒ 2) mono The acrylate is -30 ° C and the 2-acryloyloxyethyl-pumponic acid is -40 ° C.

<< weight average molecular weight of specific (meth) acrylic-type copolymer (A) >>

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is in the range of 200,000 or more and 2 million or less, preferably in the range of 250,000 or more and 1,000,000 or less, and in the range of 300,000 or more and 800,000 or less It is more preferable, and it is still more preferable that it is 350,000 or more and 550,000 or less.

When the weight average molecular weight (Mw) of a specific (meth) acrylic-type copolymer (A) is 200,000 or more, it tends to become easy to obtain cohesion.

When the weight average molecular weight (Mw) of a specific (meth) acrylic-type copolymer (A) is 2 million or less, coating property tends to become easy to improve.

The weight average molecular weight (Mw) of a specific (meth) acrylic-type copolymer (A) is a value measured by the following method. Specifically, it is measured according to the following (1) to (3).

(1) A solution of a specific (meth) acrylic copolymer (A) is applied to a release paper, and dried at 100 ° C. for 1 minute to obtain a film-shaped specific (meth) acrylic copolymer (A).

(2) A sample solution having a solid content concentration of 0.2% by mass is obtained by using the specific (meth) acrylic copolymer (A) in the film form obtained in the above (1) and tetrahydrofuran.

(3) Using gel permeation chromatography (GPC), the weight average molecular weight (Mw) of a specific (meth) acrylic copolymer (A) is measured as a standard polystyrene conversion under the following conditions.

~ Condition ~

Measuring device: High speed GPC [Model No .: HLC-8220 GPC, manufactured by Tosoh Corporation]

Detector: Differential Refractometer (RI) (assembled on HLC-8220, manufactured by Tosoh Corporation)

Column: TSK-GEL GMHXL [Tosoh Co., Ltd.] connected in series 4

Column temperature: 40 ° C

Eluent: Tetrahydrofuran

Sample concentration: 0.2% by mass

Injection volume: 100 μL

Flow rate: 0.6 mL / min

<< content of specific (meth) acrylic copolymer (A) >>

The content of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and is preferably in the range of 50% by mass or more and 99% by mass or less relative to the total solid content in the pressure-sensitive adhesive composition, for example. , It is more preferably in the range of 60% by mass or more and 90% by mass or less, and more preferably in the range of 70% by mass or more and 80% by mass or less.

If the content ratio of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is 50% by mass or more with respect to the total solids content in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive that can occur when peeling at a high speed is more sufficiently suppressed There is a tendency to form layers.

When the content ratio of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is 99% by mass or less with respect to the total solid content in the pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer having a better balance of low-speed peeling power and high-speed peeling power can be formed. I tend to be.

In the present specification, "the total solid content in the adhesive composition" means the total mass of the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition does not contain a volatile component such as a solvent, and the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition contains a volatile component such as a solvent In, it means the mass of the residue excluding volatile components such as solvents.

[Specific (meth) acrylic copolymer (B)]

The pressure-sensitive adhesive composition of the present invention includes a structural unit derived from n-butyl methacrylate and a structural unit derived from a monomer having a hydroxyl group, and has a glass transition temperature in the range of 0 ° C or higher and 45 ° C or lower, and has a weight average molecular weight. It includes (meth) acrylic-type copolymer (B) (that is, specific (meth) acrylic-type copolymer (B)) which is in the range of 10,000 to 200,000 or less.

Moreover, content of the specific (meth) acrylic-type copolymer (B) in the adhesive composition of this invention is 1 mass part or more and 70 mass parts or less with respect to 100 mass parts of specific (meth) acrylic-type copolymers (A).

<Constituent unit derived from n-butyl methacrylate>

Certain (meth) acrylic copolymers (B) contain constituent units derived from n-butyl methacrylate.

In the present specification, "the structural unit derived from n-butyl methacrylate" means a structural unit formed by addition polymerization of n-butyl methacrylate.

The content rate of the structural unit derived from n-butyl methacrylate in the specific (meth) acrylic copolymer (B) is not particularly limited.

The content rate of the structural unit derived from n-butyl methacrylate in the specific (meth) acrylic copolymer (B) is, for example, 40% by mass or more with respect to the total structural unit of the specific (meth) acrylic copolymer (B) It is preferable, more preferably 50% by mass or more, and even more preferably 60% by mass or more.

If the content rate of the structural unit derived from n-butyl methacrylate in the specific (meth) acrylic copolymer (B) is 40% by mass or more with respect to the total structural unit of the specific (meth) acrylic copolymer (B) (meth) Since the compatibility with the acrylic copolymer (A) becomes better, there is a tendency to form a pressure-sensitive adhesive layer in which haze is further suppressed.

In addition, the content rate of the constitutional unit derived from n-butyl methacrylate in the specific (meth) acrylic copolymer (B) is, for example, 99.9% by mass relative to the total constitutional unit of the specific (meth) acrylic copolymer (B). It is preferably the following, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

An isocyanate-based crosslinking agent if the content of the constituent units derived from n-butyl methacrylate in the specific (meth) acrylic copolymer (B) is 99.9% by mass or less with respect to the total constituent units of the specific (meth) acrylic copolymer (B) Since it crosslinks more appropriately, there is a tendency that a pressure-sensitive adhesive layer having a better balance of low-speed peeling power and high-speed peeling power can be formed.

<Constituent unit derived from a monomer having a hydroxyl group>

The specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having a hydroxyl group.

In the present specification, "a structural unit derived from a monomer having a hydroxyl group" means a structural unit formed by addition polymerization of a monomer having a hydroxyl group.

The type of the monomer having a hydroxyl group is not particularly limited.

Since the specific example of the monomer which has a hydroxyl group is the same as the specific example of the monomer which has a hydroxyl group in a specific (meth) acrylic-type copolymer (A), description is abbreviate | omitted here.

As a monomer having a hydroxyl group, for example, hydroxyalkyl (meth) acrylate is preferable from the viewpoint of good copolymerization with n-butyl methacrylate.

As a hydroxyalkyl (meth) acrylate, for example, from the viewpoint of good compatibility with n-butyl methacrylate and good copolymerizability and good reactivity with an isocyanate-based crosslinking agent, a hydroxyalkyl group having 1 to 5 carbon atoms. A hydroxyalkyl (meth) acrylate having a amine is preferred, and a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable.

The specific (meth) acrylic copolymer (B) may contain only one type of structural unit derived from a monomer having a hydroxyl group, or may include two or more types.

Although the content rate of the structural unit derived from the monomer which has a hydroxyl group in a specific (meth) acrylic-type copolymer (B) is not specifically limited, For example, 0.1 mass with respect to all the structural units of a specific (meth) acrylic-type copolymer (B) It is preferably in the range of% to 20% by mass, more preferably in the range of 0.7% to 15% by mass, and more preferably in the range of 1% by mass to 10% by mass.

It is specific (meth) acrylic that the content ratio of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) is 0.1% by mass or more with respect to the total structural units of the specific (meth) acrylic copolymer (B) It means that the copolymer (B) actively contains a structural unit derived from a monomer having a hydroxyl group.

When the content rate of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) is 20% by mass or less with respect to the total structural unit of the specific (meth) acrylic copolymer (B), low-speed peeling force and high speed There is a tendency that an adhesive layer having a better balance of peeling force can be formed.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer different from n-butyl methacrylate>

The specific (meth) acrylic copolymer (B) is a structural unit derived from a (meth) acrylic acid alkylester monomer different from n-butyl methacrylate (hereinafter also referred to as another (meth) acrylic acid alkylester monomer (b)). It is preferred to include.

The structural unit derived from another (meth) acrylic acid alkyl ester monomer (b) contributes to the adjustment of the adhesive force of the formed adhesive layer.

In the present specification, "the structural unit derived from another (meth) acrylic acid alkylester monomer (b)" means a structural unit formed by addition polymerization of another (meth) acrylic acid alkylester monomer (b).

As other (meth) acrylic acid alkylester monomer (b), if it is a (meth) acrylic acid alkylester monomer different from n-butyl methacrylate, the kind is not specifically limited.

As another (meth) acrylic acid alkylester monomer (b), an unsubstituted (meth) acrylic acid alkylester monomer is preferable.

The alkyl group of the other (meth) acrylic acid alkyl ester monomer (b) may be linear, branched or cyclic.

Further, the number of carbon atoms of the alkyl group is preferably 1 to 18, and more preferably 1 to 12, from the viewpoint of adhesion to the adherend of the pressure-sensitive adhesive layer to be formed and adhesion of the protective film to the base material.

Other (meth) acrylic acid alkyl ester monomers (b) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butylacrylate (n-BA), i-butyl (meth) acrylate, and s-butyl ( Meth) acrylate, t-butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate , i-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, and the like.

Among these, other (meth) acrylic acid alkyl ester monomers (b), for example, have good copolymerizability with n-butyl methacrylate (n-BMA), and also have a suitable glass transition temperature (Tg) to achieve the desired adhesive performance. Ethyl methacrylate (EMA) is preferred from the viewpoint of easy to obtain. Moreover, as another (meth) acrylic-acid alkylester monomer (b), n-butyl acrylate (n-BA) is preferable from a viewpoint of compatibility with a specific (meth) acrylic copolymer (A), for example.

When a specific (meth) acrylic-type copolymer (B) contains the structural unit (b) derived from another (meth) acrylic acid alkylester monomer, the structural unit (b) derived from another (meth) acrylic acid alkylester monomer is 1 The species may be included, or two or more may be included.

When a specific (meth) acrylic copolymer (B) contains the structural unit derived from another (meth) acrylic acid alkylester monomer (b), another (meth) acrylic acid alkyl in the specific (meth) acrylic copolymer (B) It is preferable that the content rate of the structural unit derived from the ester monomer (b) is 0.1 mass% or more and 59.9 mass% or less with respect to the whole structural unit of a specific (meth) acrylic-type copolymer (B), for example.

<Constituent unit derived from a monomer having a carboxyl group>

The specific (meth) acrylic copolymer (B) may contain a structural unit derived from a monomer having a carboxy group.

When a specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having a carboxy group, the high-speed peeling force of the pressure-sensitive adhesive layer formed decreases, and the balance between the low-speed peeling force and the high-speed peeling force tends to be better. .

The type of the monomer having a carboxyl group is not particularly limited.

Since the specific example of the monomer which has a carboxy group is the same as the specific example of the monomer which has a carboxy group in a specific (meth) acrylic-type copolymer (A), description is abbreviate | omitted here.

As the monomer having a carboxy group, for example, acrylic acid (AA) is preferred from the viewpoint of good reactivity with an isocyanate-based crosslinking agent.

When a specific (meth) acrylic-type copolymer (B) contains the structural unit derived from the monomer which has a carboxy group, it may contain only one structural unit derived from the monomer which has a carboxy group, and may contain 2 or more types.

When the specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having a carboxy group, the content rate of the structural unit derived from a monomer having a carboxyl group in the specific (meth) acrylic copolymer (B) is specific It is preferable that it is the range of 0.1 mass% or more and 5 mass% or less with respect to the whole structural unit of (meth) acrylic-type copolymer (B), It is more preferable that it is the range of 0.3 mass% or more and 3 mass% or less, More preferably, it is 0.5 mass% or more. It is more preferable that it is 1.5 mass% or less of range.

When the content rate of the structural unit derived from the monomer having a carboxyl group in the specific (meth) acrylic copolymer (B) is 0.1% by mass or more with respect to the total structural unit of the specific (meth) acrylic copolymer (B), the low-speed peeling force and high speed There is a tendency that an adhesive layer having a better balance of peeling force can be formed.

When the content rate of the structural unit derived from the monomer having a carboxyl group in the specific (meth) acrylic copolymer (B) is 5% by mass or less with respect to the total structural unit of the specific (meth) acrylic copolymer (B), when peeling at high speed There is a tendency to be able to form a pressure-sensitive adhesive layer is more sufficiently suppressed the jinging phenomenon that can occur in the.

<Other components>

The specific (meth) acrylic copolymer (B) is derived from a monomer having a structural unit and a hydroxyl group derived from the above-described structural unit, that is, an essential structural unit, n-butyl methacrylate, within a range in which the effects of the present invention are exhibited. Constituent units and other structural units derived from other (meth) acrylic acid alkyl ester monomers (b) and structural units other than those derived from monomers having a carboxyl group (so-called other structural units) do.

The monomer constituting the other constitutional units is not particularly limited as long as it can be copolymerized with the monomer constituting the constitutional units described above.

The specific examples of the monomers constituting the other structural units are the same as the specific examples of the monomers constituting the other structural units in the specific (meth) acrylic copolymer (A), so the description is omitted here.

<< glass transition temperature of a specific (meth) acrylic-type copolymer (B) >>

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is in the range of 0 ° C or more and 45 ° C or less, preferably in the range of 5 ° C or more and 40 ° C or less, and in the range of 10 ° C or more and 35 ° C or less It is more preferable.

When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is 0 ° C or higher, an adhesive layer having a good balance of low-speed peeling power and high-speed peeling power can be formed.

When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is 45 ° C. or less, a pressure-sensitive adhesive layer capable of sufficiently suppressing the jinging phenomenon that may occur when peeling at a high speed can be formed.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is a value calculated by the same method as the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) described above.

<< weight average molecular weight of specific (meth) acrylic-type copolymer (B) >>

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is in the range of 10,000 or more and 200,000 or less, preferably in the range of 10,000 or more and 150,000 or less, and in the range of 150,000 or more and 150,000 or less It is more preferable, and it is still more preferable that it is 20,000 or more and 100,000 or less in range.

When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is 10,000 or more, a pressure-sensitive adhesive layer having a good balance of low-speed peeling power and high-speed peeling power can be formed.

If the weight-average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is 200,000 or less, it is possible to form a pressure-sensitive adhesive layer that is sufficiently suppressed in the case of peeling at high speed. In addition, since compatibility with a specific (meth) acrylic copolymer (A) is improved, an adhesive layer having excellent transparency can be formed.

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is a value measured by the same method as the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) described above.

《Content of specific (meth) acrylic copolymer (B)》

The content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is in the range of 1 part by mass to 70 parts by mass with respect to 100 parts by mass of the specific (meth) acrylic copolymer (A), and 3 parts by mass It is preferably in the range of not less than 60 parts by mass, more preferably in the range of not more than 10 parts by mass and not more than 60 parts by mass, more preferably in the range of not more than 10 parts by mass and not more than 50 parts by mass.

When the content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is 1 part by mass or more with respect to 100 parts by mass of the specific (meth) acrylic copolymer (A), the balance between the low-speed peeling force and the high-speed peeling force is A good adhesive layer can be formed.

If the content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is 70 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic copolymer (A), it may occur when peeling at a high speed. It is possible to form the pressure-sensitive adhesive layer with sufficiently suppressed development. In addition, an adhesive layer having excellent transparency can be formed.

〔Production method for specific (meth) acrylic copolymers〕

The manufacturing method of a specific (meth) acrylic copolymer (A) and a specific (meth) acrylic copolymer (B) [namely, a specific (meth) acrylic copolymer] is not specifically limited.

The specific (meth) acrylic copolymer can be produced by polymerizing the aforementioned monomers by known polymerization methods, such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

The glass transition temperature (Tg) of a specific (meth) acrylic copolymer can be appropriately adjusted, for example, by using two or more monomers having different glass transition temperatures (Tg) when used as a homopolymer.

Moreover, the weight average molecular weight (Mw) of a specific (meth) acrylic-type copolymer can be made into a desired value by adjusting polymerization temperature, polymerization time, the amount of organic solvent used, the type of polymerization initiator, the amount of polymerization initiator used, and the like.

As a polymerization method, in preparing the pressure-sensitive adhesive composition of the present invention after production, a solution polymerization method is preferable because the treatment step is relatively simple and can be performed in a short time.

In the solution polymerization method, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent, if necessary, are put in a polymerization tank, and the mixture is heated for several hours while stirring in a nitrogen stream and / or reflux temperature of the organic solvent. In this case, at least a part of the organic solvent, monomer, polymerization initiator and / or chain transfer agent may be sequentially added.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbon compounds, aliphatic or alicyclic hydrocarbon compounds, ester compounds, ketone compounds, glycol ether compounds, and alcohol compounds.

More specifically, the organic solvent used in the polymerization reaction is, for example, benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin And aromatic hydrocarbon compounds represented by aromatic naphthas, aliphatic or cycloaliphatic hydrocarbons represented by n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha and terepine oil. Compounds, ester compounds represented by ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate and methyl benzoate, acetone, methyl ethyl ketone, Ketone compounds represented by methyl-i-butyl ketone, isophorone, cyclohexanone and methylcyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, di Glycol ether compounds represented by ethylene glycol monoethyl ether and diethylene glycol monobutyl ether, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and and alcohol compounds represented by t-butyl alcohol.

In the polymerization reaction, only one of these organic solvents may be used, or two or more of them may be mixed and used.

When preparing a specific (meth) acrylic copolymer, it is preferable to use an organic solvent that is difficult to cause chain transfer during polymerization reactions such as an aromatic hydrocarbon compound, an ester compound, a ketone compound, an alcohol compound, and in particular, a specific (meth) acrylic copolymer The use of toluene, ethyl acetate, methyl ethyl ketone, t-butyl alcohol, etc. is preferred from the viewpoint of solubility and ease of polymerization reaction.

Examples of the polymerization initiator include organic peroxides and azo compounds used in ordinary solution polymerization methods.

Examples of the organic peroxide are t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl Peroxydicarbonate, t-butylperoxypivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylper Oxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, And 2,2-bis (4,4-di-t-butylperoxycyclohexyl) butane and 2,2-bis (4,4-di-t-octylperoxycyclohexyl) butane.

Examples of the azo compound include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2,4-dimethylvaleronitrile) (ABVN), and 2,2'-azobis ( 4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile) and 2,2'-azobis (isobutyric acid) dimethyl.

During the polymerization reaction, only one of these polymerization initiators may be used, or two or more of them may be mixed and used.

In the production of a specific (meth) acrylic copolymer, it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and particularly preferably to use an azobis-based polymerization initiator.

The amount of the polymerization initiator is not particularly limited, and is appropriately set depending on the molecular weight of the specific (meth) acrylic copolymer to be targeted.

In the production of a specific (meth) acrylic copolymer, a chain transfer agent may be used if necessary so long as it does not impair the object and effect of the present invention.

As the chain transfer agent, for example, cyanoacetic acid, an alkylester compound having 1 to 8 carbon atoms of cyanoacetic acid, bromoacetic acid, an alkylester compound having 1 to 8 carbon atoms of bromoacetic acid, α-methylstyrene, anthracene, phenanthrene, Aromatic compounds represented by fluorene and 9-phenylfluorene, aromatic nitro compounds represented by p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol and p-nitrotoluene, benzoquinone and Benzoquinone derivatives represented by 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives represented by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoe Halogenated hydrocarbon compounds represented by carbon, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane and 3-chloro-1-propene, aldehyde compounds represented by chloral and furalde, carbon number 1 ~ 18 alkyl mercaptan compounds, aromatic mercaptan compounds represented by thiophenol and toluene mercaptan, mercaptoacetic acid, alkylester compounds having 1 to 10 carbon atoms of mercaptoacetic acid, hydroxyalkyl mercaptan compounds having 1 to 12 carbon atoms , Terpene compounds represented by pinene and terpinolene.

When a chain transfer agent is used in the production of a specific (meth) acrylic copolymer, the amount of the chain transfer agent is not particularly limited, and is appropriately set depending on the molecular weight of the target specific (meth) acrylic copolymer.

The polymerization temperature is not particularly limited, and is appropriately set depending on the molecular weight of the specific (meth) acrylic copolymer desired.

(Isocyanate-based crosslinking agent)

The pressure-sensitive adhesive composition of the present invention contains an isocyanate-based crosslinking agent.

As used herein, "isocyanate-based crosslinking agent" means a compound having two or more isocyanate groups in a molecule (so-called polyisocyanate compound). However, the isocyanate-based crosslinking agent in the present specification does not include a compound having an isocyanate group and a polysiloxane structure and an alkylene oxide structure. In the present specification, a compound having an isocyanate group, a polysiloxane structure, and an alkylene oxide structure is referred to as a “silicone-based isocyanate compound”, and details will be described later.

Examples of the isocyanate-based crosslinking agent include aromatic polyisocyanate compounds such as xylylene diisocyanate (XDI), diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), and pentamethylene diisocyanate. And aliphatic or alicyclic polyisocyanate compounds such as isocyanate (PDI), isophorone diisocyanate, and hydrogenated products of aromatic polyisocyanate compounds.

Moreover, as an isocyanate type crosslinking agent, the dimer of the said polyisocyanate compound, the trimer of the said polyisocyanate compound, the pentamer of the said polyisocyanate compound, the adduct body of the said polyisocyanate compound and a polyol compound (for example, trimethylolpropane), And burettes of the isocyanate compounds.

Among them, as an isocyanate-based crosslinking agent, hexamethylene diisocyanate (HMDI) is preferable, for example, from the viewpoint of easy to express desired adhesion and haze can be further suppressed.

A commercial item can be used as a polyisocyanate compound.

Examples of commercially available products of the polyisocyanate compound are "Colonate (registered trademark) HX", "Clonate (registered trademark) HL-S", "Clonate (registered trademark) L", "Clonate (registered trademark) L-45E" , "Colonate (registered trademark) 2031", "Colonate (registered trademark) 2030", "Colonate (registered trademark) 2234", "Colonate (registered trademark) 2785", "Aquanate (registered trademark) 200" And "Aquanate (registered trademark) 210" [above, manufactured by Tosoh Corporation], "Smidule (registered trademark) N3300", "Death module (registered trademark) N3400" and "Smidule (registered trademark) N-75 」[Above, Sumika Kobestro Urethane Co., Ltd.]," Duranate (registered trademark) E-405-80T "," Duranate (registered trademark) AE700-100 "," Duranate (registered trademark) 24A- 100 "and" Duranate (registered trademark) TSE-100 "(above, Asahi Kasei Co., Ltd.)," Takenate (registered trademark) D-110N "," Takenate (registered trademark) D-120N "," Takenate (registered trademark) M-631N "," MT-Ollester (registered trademark) NP1200 "and" Stavio (registered trademark) XD-340N "(above, manufactured by Mitsui Chemical Co., Ltd.).

The pressure-sensitive adhesive composition of the present invention may contain only one type of isocyanate-based crosslinking agent, or may contain two or more types.

The content of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and is preferably in the range of 0.1 parts by mass or more and 10.0 parts by mass or less, and 0.3 parts by mass or more and 7.0 parts by mass with respect to 100 parts by mass of the specific (meth) acrylic copolymer. It is more preferably in the range of parts by mass or less, more preferably in the range of 0.5 parts by mass or more and 6.0 parts by mass or less, and particularly preferably in the range of 1.0 part by mass or more and 5.0 parts by mass or less.

The content of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition of the present invention is 0.1 parts by mass or more with respect to 100 parts by mass of a specific (meth) acrylic copolymer, which means that the pressure-sensitive adhesive composition of the present invention actively contains an isocyanate-based crosslinking agent.

When the content of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition of the present invention is 10.0 parts by mass or less with respect to 100 parts by mass of a specific (meth) acrylic copolymer, the pressure-sensitive adhesive layer is not excessively deteriorated in wetness to the adherend of the pressure-sensitive adhesive layer to be formed. It tends to exhibit a more suitable low-speed peeling force. In addition, there is a tendency that the zip phenomenon, which may occur when peeling at a high speed, is more sufficiently suppressed.

〔Organic solvent〕

The pressure-sensitive adhesive composition of the present invention may contain an organic solvent.

The organic solvent contributes to improving the coating properties of the pressure-sensitive adhesive composition.

As an organic solvent, the thing similar to the organic solvent used at the time of the polymerization reaction of the above-mentioned specific (meth) acrylic-type copolymer is mentioned, for example.

In the case where the pressure-sensitive adhesive composition of the present invention contains an organic solvent, only one type of organic solvent may be included, or two or more types may be included.

When the pressure-sensitive adhesive composition of the present invention contains an organic solvent, the content of the organic solvent is not particularly limited, and can be appropriately set according to the purpose.

〔Other Ingredients〕

The pressure-sensitive adhesive composition of the present invention may contain components (so-called other components) other than the above-described components as necessary within a range not impairing the effects of the present invention.

As other components, silicone type isocyanate compounds, silicone type compounds other than silicone type isocyanate compounds (hereinafter also referred to as "other silicone compounds"), ionic compounds, polymers other than specific (meth) acrylic copolymers, crosslinking agents other than isocyanate type crosslinking agents ( For example, metal chelate-based crosslinking agents), crosslinking catalysts, tackifiers, antioxidants, colorants (for example, dyes and pigments), and light stabilizers (for example, ultraviolet absorbers).

<Silicone-based isocyanate compound>

The pressure-sensitive adhesive composition of the present invention may contain a compound having an isocyanate group, a polysiloxane structure, and an alkylene oxide structure (ie, a silicone-based isocyanate compound) in addition to the aforementioned isocyanate-based crosslinking agent.

Since the silicone-based isocyanate compound has an isocyanate group, it is easily reacted with a crosslinkable functional group in a specific (meth) acrylic copolymer to form a crosslinked structure, and is easily maintained in an anchored state in the pressure-sensitive adhesive layer. Therefore, the electrodeposition of the contaminant component to the surface of the adherend is suppressed when the protective film is peeled. Accordingly, when the pressure-sensitive adhesive composition of the present invention contains a silicone-based isocyanate compound, there is a tendency to form a pressure-sensitive adhesive layer excellent in contamination resistance.

In addition, since the silicone-based isocyanate compound has a polysiloxane structure in the molecule, it is difficult to be compatible with a specific (meth) acrylic copolymer and tends to be localized near the surface of the pressure-sensitive adhesive layer. Furthermore, since the silicone-based isocyanate compound has an alkylene oxide structure in the molecule, it tends to be localized near the surface of the pressure-sensitive adhesive layer in a state of being assigned to an antistatic agent, such as a silicone compound having an alkylene oxide structure used as an antistatic aid. Therefore, the silicone-based isocyanate compound can impart excellent antistatic performance in a small amount to the formed pressure-sensitive adhesive layer.

In the present specification, "polysiloxane structure" refers to a structure in which a siloxane group (-Si-O-) is connected.

The number of silicon atoms contained in the polysiloxane structure in the silicone-based isocyanate compound is preferably in the range of 1 to 100.

The silicone-based isocyanate compound has a reactive group and can be obtained by reaction of a silicone compound having an alkylene oxide structure with an isocyanate compound (hereinafter also referred to as "pre-reaction").

Reactive groups such as hydroxyl groups, carboxyl groups, substituted or unsubstituted amide groups, substituted or unsubstituted amino groups, epoxy groups, mercapto groups, and silicon-containing groups as reactive groups in silicone compounds having a reactive group and having an alkylene oxide structure Can be lifted.

Among them, as the reactive group, for example, a hydroxyl group is preferred from the viewpoint of effectively promoting the reaction of the reactive group with an isocyanate group (NCO group) in the isocyanate compound, and also effectively suppressing the occurrence of contamination on the adherend.

The reactive group may be introduced into any of the sock end, one end, and side chain of the silicone compound having an alkylene oxide structure.

Here, "one end" means, for example, one end of the main chain of a silicone compound having a polysiloxane chain (so-called main chain) having a repeating unit of a siloxane group. The term "sock end" means, for example, both ends of the main chain of a silicone compound having a molecular chain (so-called main chain) having a repeating unit of a siloxane group.

Examples of the silicone compound having a reactive group and having an alkylene oxide structure include, for example, a compound in which a alkylene oxide structure is bonded to a silicon chain (so-called polysiloxane main chain) in a graft shape or a compound in a block shape.

Examples of the compound having an alkylene oxide structure include polyethylene oxide having a reactive group, polypropylene oxide, and the like, or polyalkylene oxide in which ethylene oxide and propylene oxide are added in a block shape or at random.

The silicone compound having a reactive group and having an alkylene oxide structure, for example, exhibits excellent antistatic properties, and also has hydroxyl groups at the ends of the alkylene oxide structure and the alkylene oxide structure from the viewpoint of effectively suppressing contamination to the adherend. It is preferable that it is a silicone compound containing a bonded structure (hereinafter also referred to as "a specific alkylene oxide structure-containing silicone compound").

When a specific alkylene oxide structure-containing silicone compound has a structure in which a hydroxyl group is bonded to the terminal of the alkylene oxide structure, it becomes possible to exhibit more excellent stain resistance.

The silicone compound having an alkylene oxide chain tends to localize near the surface of the pressure-sensitive adhesive layer by interacting with an antistatic agent described later. As a result, it is estimated that the surface resistance value at the surface of the pressure-sensitive adhesive layer is lowered. When the pressure-sensitive adhesive composition contains a silicone-based isocyanate compound, it becomes possible to suppress the amount of the antistatic agent in the pressure-sensitive adhesive composition.

As a silicone compound containing a specific alkylene oxide structure from the viewpoint of imparting antistatic property and reducing contamination to an adherend, a structural unit derived from dialkylsiloxane and a composition derived from alkyl (hydroxypolyalkyleneoxyalkyl) siloxane It is preferable that it is a polysiloxane compound containing a unit.

The number of carbon atoms of the alkyl group in the dialkylsiloxane is preferably 1 to 4, more preferably 1.

In addition, the number of carbon atoms in the alkylene oxide chain in the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane is preferably 2 to 4, and more preferably 2 to 3.

The content of the alkylene oxide chain in the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane is preferably 1 to 100, more preferably 10 to 100.

The alkyl (hydroxypolyalkyleneoxyalkyl) siloxane preferably has 1 to 4 carbon atoms in the alkyl group.

When the specific alkylene oxide structure-containing silicone compound contains a structural unit derived from dialkylsiloxane and a structural unit derived from alkyl (hydroxypolyalkyleneoxyalkyl) siloxane, the number of constituent units derived from dialkylsiloxane It is preferable that it is 100 or less, and it is more preferable that it is 1-80. Moreover, it is preferable that the content number of the structural unit derived from the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane is 2-100, and it is more preferable that it is 2-80.

It is preferable that the specific alkylene oxide structure-containing silicone compound is a compound represented by the following general formula (3) or general formula (4) from the viewpoint of lowering adhesion, antistatic properties and contamination to adherends.

In general formula (3), p represents the integer of 0-100 as a repeating number of a dimethylsiloxane structural unit. q is a repeating number of a methyl propylene siloxane structural unit having a polyethylene oxide chain and represents an integer of 2 to 100. a represents the integer of 1-100 as the repeating number of an ethylene oxide structural unit.

Here, when the compound represented by the general formula (3) is an aggregate of a plurality of compounds, p, q and a are rational numbers as an average value as an aggregate of the compounds.

The repeating number a of the ethylene oxide structural unit is an integer of 1 to 100, and is preferably an integer of 10 to 100. When a is 1 or more, sufficient conductivity can be obtained, and the antistatic effect tends to be further improved. Moreover, when a is 100 or less, it becomes easy to localize in the vicinity of the surface of an adhesive layer.

The repeating number p of the dimethylsiloxane structural unit is an integer from 0 to 100, and is preferably an integer from 1 to 80. When p is 0 or more, the antistatic effect tends to be improved. In addition, when p is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be more improved.

The repeating number q of the methyl propylene siloxane structural unit is an integer of 2 to 100, and preferably an integer of 2 to 80. When q is 2 or more, it is easy to obtain sufficient conductivity and tends to improve the antistatic effect. In addition, when q is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be more improved.

As a specific example of the compound represented by general formula (3), "SF-8428", "FZ-2162", "SH-3773M", "FZ-77", "FZ-2104", "FZ-2110", "L- 7001 "," L-7002 "," SH-3749 ", etc. [above, Torre Dow Corning Co., Ltd. product] is mentioned.

In General Formula (4), R ¹ and R ² each independently represent an alkylene group having 1 to 6 carbon atoms, c represents an integer of 10 to 80, and d is 1 as a repeating number of ethylene oxide (EO) structural units. Represents the above integer, e represents the integer of 0 or more as the number of repetitions of the propylene oxide (PO) structural unit, and d + e represents the integer of 1 to 30. The order of ethylene oxide and propylene oxide may be random.

As a specific example of the compound represented by general formula (4), "BY-16-201", "SF-8427", etc. [above, Tore Dow Corning Co., Ltd. product] is mentioned.

Although the weight average molecular weight (Mw) of a specific alkylene oxide structure containing silicone compound is not specifically limited, For example, it is preferable that it is the range of 0.1 million or more and 20,000 or less, and it is more preferable that it is the range of 0.3 million or more and 1.5 million or less. .

The weight average molecular weight (Mw) of the specific alkylene oxide structure-containing silicone compound is a value measured by the same method as the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) described above.

The HLB value of the specific alkylene oxide structure-containing silicone compound is not particularly limited.

The HLB value of a specific alkylene oxide structure-containing silicone compound is preferably in the range of 5 or more and less than 16 from the viewpoint of compatibility with a specific (meth) acrylic copolymer, easy to localize, and adhesion to a protective film. , It is more preferably in the range of 7 or more and 15 or less.

The HLB value is a measure of the balance of hydrophilicity and hydrophobicity of a silicone compound having an alkylene oxide structure. In this specification, the definition of the Griffin method calculated by the following formula is followed. In addition, when a silicone having an alkylene oxide structure is a commercial product, the catalog data of the commercial product is given priority.

HLB = {(total amount of food in the hydrophilic group part) / (molecular weight of the silicone compound having an alkylene oxide structure)} × 20

The specific alkylene oxide structure-containing silicone compound may be selected from the commercially available products described above, or may be obtained by grafting an organic compound having an unsaturated bond and a polyethylene oxide chain to a dimethylpolysiloxane main chain having silicon hydride by a hydrosilylation reaction.

The isocyanate compound used for the pre-reaction of the silicone-based isocyanate compound is not particularly limited as long as it has the above-mentioned reactive group and can react with a silicone compound having an alkylene oxide structure.

As such an isocyanate compound, the polyisocyanate compound which is an isocyanate type crosslinking agent mentioned above is mentioned, for example, It is the same as the specific example of an isocyanate type crosslinking agent.

For example, from the viewpoint of reactivity in the pre-reaction, at least one selected from isophorone diisocyanate or xylylene diisocyanate and hexamethylene diisocyanate and isocyanurate modified products of polyols is preferable as the isocyanate compound used in the pre-reaction. It is more preferable that it is at least one of isophorone diisocyanate and xylylene diisocyanate from the viewpoint of particularly suppressing gelation during pre-reaction described later.

For example, from the viewpoint of antistatic properties, it is preferable that the isocyanate compound used in the pre-reaction is an isocyanate compound different from the polyisocyanate compound, which is the aforementioned isocyanate-based crosslinking agent.

If the isocyanate compound used for the pre-reaction of the polyisocyanate compound and the silicone isocyanate compound, which is the aforementioned isocyanate-based crosslinking agent, is different, the above-mentioned isocyanate-based cross-linking agent, the polyisocyanate compound and the silicone-based isocyanate compound are difficult to use, and the silicone-based isocyanate compound is more an adhesive. Since it tends to be localized on the surface of the layer, there is a tendency to obtain better antistatic properties.

As for the isocyanate compound used for a pre-reaction, only 1 type may be used and 2 or more types may be used. For example, when isophorone diisocyanate and xylylene diisocyanate are used in combination, there is a tendency to further suppress gelation during pre-reaction.

It is preferable that a silicone type isocyanate compound contains the structure represented by following structural formula (1).

In structural formula (1), r represents an integer of 1 to 100, b represents an integer of 1 to 100, and X represents a monovalent organic group containing an isocyanate group.

The repeating number r of the methyl propylene siloxane structural unit is an integer of 1 to 100, and preferably an integer of 2 to 80. When r is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. In addition, when r is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

The repeating number b of the ethylene oxide structural unit is an integer of 1 to 100, and preferably an integer of 10 to 100. When b is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. In addition, when b is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

Examples of the monovalent organic group represented by X include a monovalent group in which one of the isocyanate groups (NCO groups) is removed from the above-described isocyanate-based crosslinking agent, a polyisocyanate compound (i.e., a bifunctional or higher isocyanate compound).

Among these, as the monovalent organic group represented by X, for example, from the viewpoint of reactivity with a specific (meth) acrylic copolymer, a chain or cyclic aliphatic polyisocyanate compound, a dimer of a chain or cyclic aliphatic polyisocyanate compound, and a chain or cyclic A monovalent group obtained by removing one isocyanate group from at least one polyisocyanate compound selected from a trimer or a pentamer containing an isocyanurate modified product of the aliphatic polyisocyanate compound of is preferred, isophorone diisocyanate, xylylene di One isocyanate group is removed from at least one polyisocyanate compound selected from trimers or pentamers including isocyanate or hexamethylene diisocyanate, dimers of hexamethylene diisocyanate and isocyanurate modified products of hexamethylene diisocyanate 1 A valent group is more preferable, and a monovalent group in which at least one isocyanate group is removed from at least one of the trimers containing isophorone diisocyanate, xylylene diisocyanate, and isocyanurate modified products of hexamethylene diisocyanate is more preferred, and isophorone Particularly preferred is a monovalent group in which at least one of diisocyanate and xylylene diisocyanate has one isocyanate group removed.

In addition, as the monovalent organic group represented by X, for example, from the viewpoint of antistatic properties, a monovalent group obtained by removing one isocyanate group (NCO group) from a difunctional or higher isocyanate compound different from the polyisocyanate compound which is the isocyanate-based crosslinking agent described above. desirable.

The specific example of the structure represented by said structural formula (1) is shown below. Moreover, the structure represented by structural formula (1) is not limited to the following exemplary structures, and if it is a structure contained in the structure represented by structural formula (1), for example, there is no restriction | limiting in particular.

As a silicone type isocyanate compound, it is preferable that it is at least 1 sort (s) selected from the group which consists of the compound represented by general formula (1-1) and general formula (2) from a viewpoint of contamination resistance, for example, and is represented by general formula (1-1). It is more preferable that it is a compound.

In the general formula (1-1), p represents an integer of 0 to 100, q and r each independently represent an integer of 1 to 100, a represents an integer of 1 to 100, and b represents 1 to 100. Represents an integer. In addition, X represents a monovalent organic group containing an isocyanate group.

Here, when the compound represented by the general formula (1-1) is an aggregate of a plurality of compounds, p, q, r, a, and b are rational numbers as an average value as an aggregate of the compounds.

The repeating number a of the ethylene oxide structural unit is an integer of 1 to 100, and is preferably an integer of 10 to 100. When a is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. Moreover, when a is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

The repeating number p of the dimethylsiloxane structural unit is an integer from 0 to 100, and is preferably an integer from 1 to 80. When p is 0 or more, the antistatic property tends to be improved. In addition, when p is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

The repeating number q of the methyl propylene siloxane structural unit is an integer of 1 to 100, and preferably an integer of 2 to 80. When q is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. In addition, when q is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

In general formula (1-1), r and b have the same meanings as r and b in structural formula (1), and preferred ranges are also the same.

In General Formula (2), R ¹ and R ² each independently represent an alkylene group having 1 to 6 carbon atoms, c represents an integer of 10 to 80, and d is 1 as a repeating number of ethylene oxide (EO) structural units. Represents the above integer, e represents the integer of 0 or more as the number of repetitions of the propylene oxide (PO) structural unit, and d + e represents the integer of 1 to 30. The order of the ethylene oxide structural unit and the propylene oxide structural unit may be random.

In the general formula (2), the alkylene group having 1 to 6 carbon atoms represented by R ¹ or R ² is not particularly limited, and examples thereof include a methylene group, an ethylene group, a propylene group, and a butylene group.

The repeating number d of the ethylene oxide structural unit is preferably an integer of 1 to 100, and more preferably an integer of 10 to 100. When d is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. In addition, when d is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

The repeating number e of the propylene oxide structural unit is preferably an integer of 1 to 100, and more preferably an integer of 10 to 100. When e is 1 or more, sufficient conductivity can be obtained and antistatic properties tend to be improved. In addition, when e is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

The sum of the repeating number d of the ethylene oxide structural unit and the repeating number e of the propylene oxide structural unit is more preferably an integer of 1 to 50.

The specific example of a silicone type isocyanate compound is shown below. In addition, the silicone-based isocyanate compound is not limited to the following exemplary compounds, and is not particularly limited as long as it is a compound contained in a compound containing a structure represented by Structural Formula (1).

The method for producing the silicone-based isocyanate compound is not particularly limited, and a known production method can be applied.

For example, a silicone-based isocyanate compound can be obtained by adding a predetermined amount of a silicone compound and an isocyanate compound each having a reactive group to the reaction vessel and having an alkylene oxide structure, and uniformly stirring the mixture (pre-reaction).

The temperature of the pre-reaction is preferably 40 ° C to 100 ° C, more preferably 45 ° C to 95 ° C, and even more preferably 50 ° C to 95 ° C.

When the pressure-sensitive adhesive composition of the present invention contains a silicone-based isocyanate compound, the content of the silicone-based isocyanate compound in the pressure-sensitive adhesive composition is, for example, preferably 0.1 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic copolymer (A), It is more preferably 0.2 parts by mass to 3 parts by mass, and even more preferably 0.3 parts by mass to 2 parts by mass.

When the content of the silicone-based isocyanate compound is 0.1 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic copolymer (A), there is a tendency to form an adhesive layer having excellent stain resistance.

When the pressure-sensitive adhesive composition of the present invention contains a silicone-based isocyanate compound, the mass ratio of the silicone-based isocyanate compound to the isocyanate-based crosslinking agent (silicone-based isocyanate compound / isocyanate-based crosslinking agent) is preferably 1/1 to 1/20, 1/2 to It is more preferable that it is 1/15, and it is more preferable that it is 1/3 to 1/10.

If the mass ratio [silicone-based isocyanate compound / isocyanate-based crosslinking agent] is 1/1 or more, a specific (meth) acrylic copolymer (A) and an isocyanate-based crosslinking agent can react sufficiently to form a crosslinked structure, thereby providing a more suitable adhesive force to the pressure-sensitive adhesive layer Tend to be.

When the mass ratio [silicone-based isocyanate compound / isocyanate-based crosslinking agent] is 1/20 or less, the number of isocyanate-based crosslinking agents contained in the pressure-sensitive adhesive composition is not too large, and since the silicone-based isocyanate compound is appropriately present, an adhesive layer having excellent stain resistance can be formed. Tend to

<Other silicone compounds>

The pressure-sensitive adhesive composition of the present invention may contain at least one silicone-based compound (that is, another silicone compound) other than the silicone-based isocyanate compound within a range not impairing the effects of the present invention.

Other silicone compounds may function as an antistatic aid.

As another silicone compound, the silicone compound which has a reactive group and has an alkylene oxide structure used for the pre-reaction of a silicone type isocyanate compound is mentioned, for example.

The specific example of another silicone compound is the same as the specific example of the silicone compound which has the above-mentioned reactive group and also has an alkylene oxide structure, and the preferable range is also the same.

<Ionic compound>

The pressure-sensitive adhesive composition of the present invention may contain at least one ionic compound.

The ionic compound can function as an antistatic agent.

The ionic compound is not particularly limited.

Examples of the ionic compound include alkali metal salts and organic salts.

As the ionic compound, for example, at least one selected from the group consisting of alkali metal salts and organic salts is preferable from the viewpoint of high ion dissociation properties and easy anti-static properties even in small amounts.

The alkali metal salt is not particularly limited as long as it is a metal salt containing lithium ions (Li ⁺ ), sodium ions (Na ⁺ ), potassium ions (K ⁺ ), and rubidium (Rb ⁺ ) as cations.

Alkali metal salts, for example, Li ^+, at least one kind of cations and Cl is selected from the group consisting of Na ⁺ and ^{K + -, Br -, I} -, BF 4 -, PF 6 -, SCN -, ClO 4 -, ^{_{CF 3 SO 3 -, (FSO}} 2) 2 N -, (CF 3 SO 2) 2 N -, (C 2 F 5 SO 2) 2 N - and _{(CF 3 SO 2) 3 C} - selected from the group consisting of It is preferably a metal salt composed of at least one anion.

Among them, alkali metal salts include, for example, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ (so-called LiTFS), Li (FSO ₂ ) ₂ N, and Li (CF ₃ SO) from the viewpoint of antistatic properties. ₂ ) Lithium salts such as ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C are preferred, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ At least one lithium salt selected from the group consisting of N, Li (C ₂ F ₅ SO ₂ ) ₂ N and Li (CF ₃ SO ₂ ) ₃ C is more preferable.

Organic salts include organic cations and their cations.

Organic salts include, for example, ionic solids having a melting point of 30 ° C or higher and ionic liquids having a melting point of less than 30 ° C.

It is preferable that the organic salt is an ionic solid having a melting point of 30 ° C or higher. When the melting point of the organic salt is 30 ° C or higher, it is preferable because the transition to the adherend is small and the contamination is low.

Examples of the organic cations include imidazolium cations, pyridinium cations, alkylpyrrolidinium cations, ammonium cations having an organic group as a substituent, sulfonium cations having an organic group as a substituent, and phosphonium cations having an organic group as a substituent.

Among them, the organic cation is preferably a pyridinium cation or an imidazolium cation from the viewpoint of antistatic properties.

The anion portion serving as the cation of the organic cation is not particularly limited, and may be either an inorganic anion or an organic anion. In view anion is a counter ion of the organic cation portion antistatic property is excellent preferable that the fluorine-containing anions containing fluorine atoms, a hexafluorophosphate anion (PF ₆ ^-) is more preferably.

Examples of organic salts include pyridinium salts, imidazolium salts, alkylammonium salts, alkylpyrrolidinium salts, and alkylphosphonium salts.

Among them, the organic salt is preferably a pyridinium salt or an imidazolium salt, and more preferably a salt of a pyridinium cation, an imidazolium cation and a fluorine-containing anion.

<Crosslinking catalyst>

The pressure-sensitive adhesive composition of the present invention may contain a crosslinking catalyst.

It does not specifically limit as a crosslinking catalyst, A well-known thing can be used.

Examples of the crosslinking catalyst are organometallic compounds represented by, for example, dioctyltin dilaurate (DOTDL) and 1,3-diacetoxytetrabutylstannoxane, and tertiary amines represented by triethylenediamine and N-methylmorpholine. And compounds.

〔purpose〕

The pressure-sensitive adhesive composition of the present invention is preferably used in a protective film (so-called optical member protective film) for protecting an optical member.

The pressure-sensitive adhesive composition of the present invention has a good balance between low-speed peeling power and high-speed peeling power, and sufficiently suppresses the jing that may occur when peeling at a high speed, and also protects the optical member because an adhesive layer having excellent transparency can be formed. It is suitable for the application of sticking a film.

Examples of the optical member include members constituting devices such as image display devices and input devices (so-called optical devices) or members used in these devices.

As specific examples of the optical member, a polarizing plate, an AG (Anti-Glare) polarizing plate, a wavelength plate, a phase difference plate including a wavelength plate such as 1/2, 1/4, a visual compensation film, an optical compensation film, a brightness enhancing film, a light guide plate, and a reflection And transparent conductive films such as films, antireflection films, and indium-tin oxide (ITO) films, prism sheets, lens sheets, and diffuser plates.

As the material of the optical member, for example, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, vinyl chloride resin, And resins such as ABS (Acrylonitrile Butadiene Styrene) resin and fluorine-based resin.

[Optical member protection film]

The optical member protective film of the present invention includes a base material, an adhesive layer formed on the base material, and formed by the pressure-sensitive adhesive composition of the present invention. That is, in the protective film of this invention, the base material and the adhesive layer formed with the adhesive composition of this invention are laminated.

Since the protective film of the present invention includes the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention, it is difficult to cause defects such as peeling, displacement, etc. from the adherend, while protection is required after sticking to the surface of the adherend When it is removed from the adherend, it can be removed efficiently. In other words, the balance between the low-speed peeling force and the high-speed peeling force is good.

In addition, since the protective film of the present invention includes the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the present invention, it is difficult to cause a jing phenomenon when peeling from the adherend at high speed, and it is difficult to generate a gold-like defect on the surface of the adherend.

Furthermore, the protective film of the present invention is excellent in transparency because it includes the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention.

The base material in the protective film of the present invention is not particularly limited as long as an adhesive layer can be formed on the base material.

As the base material, for example, polyester resin, acetate resin (for example, triacetyl cellulose resin), polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic And films containing resins such as resins, vinyl chloride resins, ABS resins, and fluorine resins.

For example, from the viewpoint of inspection and management of the optical member by fluoroscopy, as the base material, polyester-based resin, acetate-based resin, polyethersulfone-based resin, polycarbonate-based resin, polyamide-based resin, polyimide-based resin, polyolefin-based A film containing at least one resin selected from the group consisting of resins and acrylic resins is preferred.

Further, for example, from the viewpoint of surface protection performance, a film containing a polyester resin is preferred, and in consideration of practicality, a film containing polyethylene terephthalate (PET) is particularly preferred.

The base material may contain various additives such as plasticizers, colorants (for example, dyes and pigments), heat stabilizers, light stabilizers, antistatic agents, and flame retardants.

Further, the base material may be partially or entirely shaped.

The thickness of the base material is generally 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less.

The lower limit of the thickness of the base material is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of the strength of the protective film, for example.

An antistatic layer may be provided on one side or both sides of the base material. In addition, surface treatment such as corona discharge treatment or plasma discharge treatment may be performed on the surface on the side where the pressure-sensitive adhesive layer of the base material is provided to improve the adhesion between the base material and the pressure-sensitive adhesive layer.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and a method commonly used may be employed.

As the method for forming the pressure-sensitive adhesive layer on the base material, for example, the following method can be adopted.

The pressure-sensitive adhesive composition of the present invention is applied on the base material as it is or diluted with a solvent as needed to form a coating film on the base material. Next, the formed coating film is dried to remove the solvent, followed by curing to form an adhesive layer on the base material.

Moreover, the surface of the exposed adhesive layer may be protected with a release film. The release film is not particularly limited as long as it can be easily peeled from the surface of the pressure-sensitive adhesive layer, and examples thereof include paper, resin film, and the like subjected to surface treatment with a release agent on one or both surfaces. As a resin film, the polyester film typified by a polyethylene terephthalate (PET) film is mentioned, for example. Examples of the release agent include fluorine-based resins, paraffin wax, silicones, and long-chain alkyl group compounds.

The release film protects the surface of the pressure-sensitive adhesive layer while providing a protective film for practical use and peels off in use.

As another method of forming the pressure-sensitive adhesive layer on the base material, for example, the following method can be adopted.

The pressure-sensitive adhesive composition of the present invention is applied on a release film, such as paper or resin film, which has been subjected to surface treatment with a release agent in an intact state or diluted with a solvent as necessary to form a coating film on the release film. Next, the formed coating film is dried to remove the solvent. Next, the pressure-sensitive adhesive layer is formed on the base material by pressing the surface of the release film on the side where the pressure-sensitive adhesive layer is formed to contact the base material and transferring the pressure-sensitive adhesive layer to the base material. Next, curing is performed.

The method of applying the pressure-sensitive adhesive composition on the base material or on the release film is not particularly limited, for example, gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, knife coater, spray coater, bar coater, applicator, etc. A well-known method using this is mentioned.

The coating amount of the pressure-sensitive adhesive composition on the base material or the release film is appropriately set depending on the thickness of the pressure-sensitive adhesive layer to be formed.

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the adhesive force required for the protective film, the type of adherend (for example, material and shape), and the surface roughness of the adherend.

The thickness of the pressure-sensitive adhesive layer is generally 1 μm or more and 100 μm or less, preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 30 μm or less.

The method of drying the coating film formed on the base material or on the release film is not particularly limited, and examples thereof include methods such as natural drying, heat drying, hot air drying, and vacuum drying.

The drying temperature and drying time of the coating film are not particularly limited, and are appropriately set depending on the thickness of the coating film, the amount of organic solvent in the coating film, and the like.

Curing is carried out for 1 day to 10 days in an environment of, for example, 23 ° C and 50% RH.

The crosslinking reaction of the pressure-sensitive adhesive composition is terminated by curing to form a pressure-sensitive adhesive layer.

The adhesive force (so-called peeling force) of the pressure-sensitive adhesive layer when the protective film adhered to the adherend is peeled 180 ° is preferably 0.10 N / 25 mm or more when the peeling speed is 0.3 m / min (that is, low-speed peeling), and 0.15 N / 25mm or more is more preferable, and 0.20N / 25mm or more is more preferable.

When the adhesive force (so-called low-speed peeling force) during low-speed peeling is 0.10 N / 25 mm or more, the occurrence of peeling or misalignment of the protective film tends to be more suppressed.

The adhesive strength (so-called peeling force) of the pressure-sensitive adhesive layer when the protective film adhered to the adherend is peeled 180 ° is preferably less than 1.50 N / 25 mm when the peeling speed is 30 m / min (ie, high-speed peeling), and 1.00 N It is more preferably less than / 25 mm, and more preferably less than 0.50 N / 25 mm.

If the adhesive force (so-called high-speed peeling force) during high-speed peeling is less than 1.50 N / 25 mm, the workability can be further improved because the protective film can be peeled more efficiently from the adherend.

In this specification, the pressure-sensitive adhesive layer having a good balance of low-speed peeling force and high-speed peeling force is evaluated based on the value (low-speed peeling force / high-speed peeling force) divided by the value of the low-speed peeling force.

(Low-speed peeling force / high-speed peeling force) is preferably 0.10 or more, more preferably 0.20 or more, and even more preferably 0.30 or more.

Example

Hereinafter, the present invention will be described more specifically by examples. The present invention is not limited to the following examples as long as it does not exceed the gist.

[Production of (meth) acrylic copolymer (A)]

(Production Example A-1)

171.0 parts by mass of ethyl acetate and 249.0 parts by mass of t-butyl alcohol were placed in a reaction vessel equipped with a thermometer, stirrer, nitrogen introduction tube, and reflux cooler.

Moreover, 360.0 parts by mass of n-butyl acrylate (n-BA) and 2-ethylhexyl acrylate [2EHA; Other acrylic acid alkyl ester monomer (a)] 217.8 parts by mass, 4-hydroxybutyl acrylate (4HBA; monomer having a hydroxyl group) 18.0 parts by mass and acrylic acid (AA; monomer having a carboxyl group) 4.2 parts by mass and mixed to form a monomer mixture Did.

20.0% by mass of this monomer mixture was added into the reaction vessel. Next, after replacing the air in the reaction vessel with nitrogen gas, 2,2'-azobisisobutyronitrile [AIBN; Polymerization initiator] 0.08 parts by mass was added and the contents of the reaction vessel were heated to 85 ° C while stirring under a nitrogen atmosphere to initiate an initial reaction.

After the initial reaction was almost finished, the contents of the reaction vessel were reacted while adding a mixture of 80.0 parts by mass of the remaining monomer mixture and 88.0 parts by mass of ethyl acetate and 0.80 parts by mass of AIBN in the reaction vessel sequentially over about 2 hours. The reaction (a1) was obtained by reacting for 2 hours.

Thereafter, a solution prepared by dissolving 0.60 parts by mass of t-butylperoxypivalate (polymerization initiator) in 132.0 parts by mass of ethyl acetate in the reactant (a1) in the reaction vessel was added dropwise over 1 hour, and after completion of dropping, an additional 1.5 hours The reaction product (a2) was obtained. The obtained reactant (a2) was diluted with ethyl acetate to obtain a solution of (meth) acrylic copolymer A-1 having a solid content of 45% by mass.

The term "solid content" as used herein refers to components other than volatile components such as solvents in the solution of (meth) acrylic copolymer A-1. The same applies to the solutions of the following (meth) acrylic copolymers A-2 to A-10.

(Production Examples A-2 to A-10)

By changing the monomer composition of the (meth) acrylic copolymer (A) in Production Example A-1 to the monomer composition shown in Table 1, and adjusting at least one of the amount of the organic solvent and the amount of the polymerization initiator, the (meth) acrylic copolymer ( (Meth) acrylic copolymer A-2 having a solid content of 45% by mass by performing the same operation as in Production Example A-1 except that the weight average molecular weight (Mw) of A) was changed to the weight average molecular weight (Mw) shown in Table 1. Each solution of -A-10 was obtained.

(Meta) Monomer composition of acrylic copolymers A-1 to A-10 (unit: mass%), glass transition temperature (Tg, unit: ° C) and weight average molecular weight [Mw, unit: 10,000 (in the table, "× 10 ⁴ ”) is shown in Table 1.

The glass transition temperature (Tg) of the (meth) acrylic copolymers A-1 to A-10 was calculated by the same method as the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) described above. In addition, the weight average molecular weight (Mw) of (meth) acrylic-type copolymer A-1-A-10 was measured by the method similar to the weight average molecular weight (Mw) of the specific (meth) acrylic-type copolymer (A) mentioned above.

Of the (meth) acrylic copolymers A-1 to A-10 obtained above, (meth) acrylic copolymers A-1 to A-7 correspond to specific (meth) acrylic copolymers (A) in the present invention.

The details of each monomer listed in Table 1 are as shown below.

`` N-BA '': n-butyl acrylate

<Other (meth) acrylic acid alkyl ester monomer (a)>

"2EHA": 2-ethylhexyl acrylate

"MA": methyl acrylate

<Monomer with hydroxyl group>

「4HBA」: 4-hydroxybutyl acrylate

<Monomer having a carboxy group>

`` AA '': acrylic acid

In Table 1, "-" means that the corresponding column monomer is not used.

In Table 1, "glass transition temperature (Tg)" is only indicated as "Tg", and "weight average molecular weight (Mw)" is only indicated as "Mw".

[Production of (meth) acrylic copolymer (B)]

(Production Example B-1)

350.0 parts by mass of ethyl acetate and 150.0 parts by mass of t-butyl alcohol were placed in a reaction vessel equipped with a thermometer, stirrer, nitrogen introduction tube, and reflux cooler.

In addition, 577.8 parts by mass of n-butyl methacrylate (n-BMA) in another container, 18.0 parts by mass of 4-hydroxybutyl acrylate (4HBA; a monomer having a hydroxyl group) and 4.2 mass of acrylic acid (AA; a monomer having a carboxyl group) Part was added and mixed to obtain a monomer mixture.

20.0% by mass of this monomer mixture was added into the reaction vessel. Next, after replacing the air in the reaction vessel with nitrogen gas, 2,2'-azobisisobutyronitrile [AIBN; Polymerization initiator] The initial reaction was initiated by adding 1.80 parts by mass and heating the temperature of the contents in the reaction vessel to 85 ° C while stirring under a nitrogen atmosphere.

After the initial reaction was almost complete, the contents of the reaction vessel were reacted while sequentially adding a mixture of 80.0 parts by mass of the remaining monomer mixture and 80.0 parts by mass of ethyl acetate and 8.0 parts by mass of AIBN in the reaction vessel, and after the completion of the addition, the contents in the reaction vessel were further added. The reaction (b1) was obtained by reacting for 1 hour.

Thereafter, a solution prepared by dissolving 0.60 parts by mass of t-butylperoxypivalate (polymerization initiator) in 132.0 parts by mass of ethyl acetate in the reactant (b1) in the reaction vessel was added dropwise over 1 hour, and further 2 hours after completion of the addition. The reaction product (b2) was obtained. The obtained reaction product (b2) was diluted with ethyl acetate to obtain a solution of (meth) acrylic copolymer B-1 having a solid content of 45% by mass.

The term "solid content" as used herein refers to components other than volatile components such as solvents in the solution of the (meth) acrylic copolymer B-1. The same applies to the solutions of the following (meth) acrylic copolymers B-2 to B-21.

(Production Examples B-2 to B-6, B-10 to B-12 and B-15 to B-21)

The (meth) acrylic copolymer ((meth) acrylic copolymer () was prepared by changing at least one of the monomer composition of the (meth) acrylic copolymer (B) in Production Example B-1 to the monomer composition shown in Table 2, and the amount of the organic solvent and the polymerization initiator. (Meth) acrylic copolymer B-2 having a solid content of 45% by mass by performing the same operation as in Production Example B-1 except that the weight average molecular weight (Mw) of B) was changed to the weight average molecular weight (Mw) shown in Table 2. Each solution of -B-6, B-10-B-12 and B-15-B-21 was obtained.

(Production Examples B-7 to B-9, B-13 and B-14)

The weight average molecular weight (Mw) of the (meth) acrylic copolymer (B) was changed to the weight average molecular weight (Mw) shown in Table 2 by adjusting at least one of the amount of the organic solvent and the amount of the polymerization initiator in Production Example B-1. The same operation as in Production Example B-1 was performed except for the respective solutions of (meth) acrylic copolymers B-7 to B-9, B-13 and B-14 having a solid content of 45% by mass.

(Meta) Monomer composition of acrylic copolymers B-1 to B-21 (unit: mass%), glass transition temperature (Tg, unit: ° C) and weight average molecular weight [Mw, unit: 10,000 (in the table, "× 10 ⁴ ”) is shown in Table 2.

The glass transition temperature (Tg) of the (meth) acrylic copolymers B-1 to B-20 was calculated by the same method as the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) described above. In addition, the glass transition temperature (Tg) of the (meth) acrylic copolymer B-21 was not calculated.

In addition, the weight average molecular weight (Mw) of (meth) acrylic-type copolymers B-1-B-21 was measured by the method similar to the weight average molecular weight (Mw) of the specific (meth) acrylic-type copolymer (A) mentioned above.

Of the (meth) acrylic copolymers B-1 to B-21 obtained above, (meth) acrylic copolymers B-1 to B-12 correspond to specific (meth) acrylic copolymers (B) in the present invention.

The details of each monomer listed in Table 2 are as shown below.

`` N-BMA '': n-butyl methacrylate

<Other (meth) acrylic acid alkyl ester monomer (b)>

「EMA」: Ethyl methacrylate

`` I-BMA '': i-butyl methacrylate

"MMA": methyl methacrylate

"2EHMA": 2-ethylhexyl methacrylate

`` CHMA '': cyclohexyl methacrylate

<Other monomers>

"MePEGMA": Methoxypolyethylene glycol methacrylate (average added mole number of alkylene oxide group: 23)

<Monomer with hydroxyl group>

「4HBA」: 4-hydroxybutyl acrylate

"2HEA": 2-hydroxyethyl acrylate

"2HEMA": 2-hydroxyethyl methacrylate

<Monomer having a carboxy group>

`` AA '': acrylic acid

In Table 2, "-" described in the column of the monomer composition means that the monomer of the corresponding column is not used.

In Table 2, "glass transition temperature (Tg)" is only indicated as "Tg", and "weight average molecular weight (Mw)" is only indicated as "Mw".

[Preparation of silicon-based isocyanate compound]

Takenate (registered trademark) 500 (trade name, xylylene diisocyanate (XDI), manufactured by Mitsui Chemicals Co., Ltd.) 118.0 parts by mass in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, a reflux cooler, and a dropping lot And SH-3773M [trade name, polyether-modified silicone compound, manufactured by Torre Dow Corning Co., Ltd.] 82.0 parts by mass, the air in the flask was replaced with nitrogen gas, and the inner temperature was raised to 50 ° C. While maintaining the internal temperature at 50 ° C, the contents in the flask were stirred for 6 hours to obtain a silicone-based isocyanate compound.

[Preparation of adhesive composition]

[Example 1]

222.2 parts by mass of a solution of (meth) acrylic copolymer A-1 (100 parts by mass as solid content) and a solution of (meth) acrylic copolymer B-1 in a four-necked flask equipped with a stirring blade, thermometer, cooler and dropping lot 66.6 Parts by mass (30 parts by mass as solids) and SH-3773M [trade name, polyether-modified silicone compound, manufactured by Torre Dow Corning Co., Ltd.] 0.30 parts by mass and LiTFS [LiCF ₃ SO ₃ , manufactured by Morita Chemical Industry Co., Ltd.] 0.25 The mass part was added and stirred for 4 hours while maintaining the liquid temperature in the flask at around 25 ° C.

Next, 12.0 parts by mass of Sumidul (trademark) N-3300 [trade name, dimer of hexamethylene diisocyanate (HMDI), manufactured by Sumika Covestro Urethane Co., Ltd.) as an isocyanate crosslinking agent in the flask 12.0 parts by mass (as solid content) 3.00 parts by mass) and stirred sufficiently to obtain an adhesive composition.

[Examples 2 to 18]

In Examples 2 to 18, except for changing the composition of the pressure-sensitive adhesive composition to the composition shown in Table 3, the same operation as in Example 1 was performed to obtain the pressure-sensitive adhesive composition.

[Examples 19 to 34]

In Examples 19-34, the composition similar to Example 1 was performed except having changed the composition of the adhesive composition to the composition shown in Table 4, and the adhesive composition was obtained.

(Comparative Examples 1 to 16)

In Comparative Examples 1 to 16, except for changing the composition of the pressure-sensitive adhesive composition to the composition shown in Table 5, the same operation as in Example 1 was performed to obtain the pressure-sensitive adhesive composition.

In Tables 3 to 5, "-" means that the corresponding component is not included.

The details of the components described in Tables 3 to 5 are as follows.

<Isocyanate-based crosslinking agent>

"N-3300" [Brand name: Sumidul (registered trademark) N-3300, Sumika Covestro Urethane Co., Ltd.): 4-fold dilution of trimer of hexamethylene diisocyanate (HMDI), solid content: 25% by mass

"L-45E" [Product name: Colonate (registered trademark) L-45E, manufactured by Tosoh Corporation]: Adduct of tolylene diisocyanate (TDI) and trimethylolpropane (TMP), solid content: 45% by mass

"N-3400" [Brand name: Death Module (registered trademark) N-3400, manufactured by Sumika Covesturo Urethane Co., Ltd.): 4-fold dilution of dimer of hexamethylene diisocyanate (HMDI), solid content: 25% by mass

"D-120" [Brand name: Takenate (registered trademark) D-120, manufactured by Mitsui Chemical Co., Ltd.): Adduct of xylylene diisocyanate (XDI) and trimethylolpropane (TMP), solid content: 75 mass %

<Other ingredients>

"SH-3773M" (trade name, manufactured by Torre Dow Corning Co., Ltd.): Polyether-modified silicone compound (having a hydroxyl group as a reactive group at the end of the polyalkyleneoxy group), other silicone compound

"LiTFS" [Morita Chemical Industry Co., Ltd.]: Lithium trifluoromethanesulfonic acid [LiCF ₃ SO ₃ ], ionic compound

"DOTDL": dioctyltin dilaurate, crosslinking catalyst

"Aluminate chelate" [Kawaken Fine Chemical Co., Ltd.]: Aluminum trisacetylacetonate, metal chelate-based crosslinking agent

"TETRAD-X" [Product name: TETRAD (registered trademark) -X, manufactured by Mitsubishi Gas Chemical Co., Ltd.): Epoxy-based crosslinking agent

[evaluation]

The following evaluation was performed using the adhesive composition prepared above.

The results are shown in Tables 6-8.

1. Peeling power

<Preparation of protective film for peeling force evaluation>

Coating amount after drying on polyethylene terephthalate (PET) film (trade name: Teijin (registered trademark) Tetoron (registered trademark) film, model number: G2, thickness: 38 μm, manufactured by Teijin Film Solutions Co., Ltd.) as a base material The adhesive composition was applied to be 15 g / m 2 to form a coating film. Next, the formed coating film was dried at 100 ° C. for 60 seconds using a hot air circulation type dryer.

Next, the exposed surface of the dried adhesive film was superimposed on the surface treated surface of a release film (trade name: FilmBiner (registered trademark) 100E-0010N023, thickness: 100 μm, manufactured by Fujimori Industries) with a silicone-based release agent. It was set as a laminate. This laminate is passed through a pair of pressurized nip rolls, pressed and glued, and then cured for 96 hours under an atmosphere of 23 ° C. and 50% RH to undergo a crosslinking reaction, thereby exfoliating power having a layered structure of a base material / adhesive layer / peel film A protective film for evaluation was obtained.

(1) Low-speed peeling force

The protective film for peeling force evaluation prepared above was cut to a size of 25 mm × 150 mm to prepare a protective film piece for peeling force evaluation.

Next, the release film is peeled from the prepared protective film piece for evaluation of peeling force, and the surface of the pressure-sensitive adhesive layer exposed by peeling is polyethylene terephthalate (PET) film [brand name: Cosmoshine (registered trademark) A4300, thickness: 300 μm, toyo After being superimposed on the surface of the Bo Co., Ltd. product, it was compressed into a test sample using a table-top laminating machine.

The test sample was allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH. Next, using a single-column type material tester [Model No .: STA-1225, manufactured by A & D Co., Ltd.] as a measuring device, peeled from the PET film under an atmosphere of 23 ° C. and 50% RH at a peel rate of 0.3 m / min. The peel force (unit: N / 25mm) when the protective film piece (adhesive layer / base material) for force evaluation was peeled 180 ° in the long side (150mm) direction was measured. And the low-speed peeling force was evaluated according to the following evaluation criteria.

When the evaluation result was "AA", "A" or "B", it was judged that the low-speed peeling power was excellent.

-Evaluation standard-

AA: The peeling force is 0.20 N / 25 mm or more.

A: The peeling force is 0.15 N / 25 mm or more and less than 0.20 N / 25 mm.

B: The peeling force is 0.10 N / 25 mm or more and less than 0.15 N / 25 mm.

C: Peeling force is less than 0.10N / 25mm.

(2) High-speed peeling force

A test sample was obtained in the same order as in the "(1) low-speed peeling force".

The test sample was allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH. Next, as a measuring device, a peeling tester [Model No .: Transverse TE-720, manufactured by Tester Industries Co., Ltd.] was used to evaluate the peeling force from the PET film under conditions of a peeling rate of 30 m / min under an atmosphere of 23 ° C. and 50% RH. The peel force (unit: N / 25 mm) when the protective film piece (adhesive layer / base material) was peeled 180 ° in the long side (150 mm) direction was measured. And the high-speed peeling force was evaluated according to the following evaluation criteria.

When the evaluation result was "AA", "A" or "B", it was judged that the high-speed peeling power was excellent.

-Evaluation standard-

AA: Peeling force is less than 0.50N / 25mm.

A: The peeling force is 0.50 N / 25 mm or more and less than 1.00 N / 25 mm.

B: Peeling force is 1.00N / 25mm or more and less than 1.50N / 25mm.

C: The peeling force is 1.50 N / 25 mm or more.

(3) Balance between low-speed peeling power and high-speed peeling power

Based on the value of the low-speed peeling force measured in the "(1) low-speed peeling force" and the value of the high-speed peeling force measured in the "(2) high-speed peeling force", the balance of the low-speed peeling force and the high-speed peeling force was evaluated. Did.

Specifically, the value of the low-speed peeling force was divided by the value of the high-speed peeling force, and the balance of the low-speed peeling force and the high-speed peeling force was evaluated according to the following evaluation criteria based on the value rounded off to the third digit after the decimal point.

When the evaluation result was "AA", "A" or "B", it was judged that the balance between the low-speed peeling force and the high-speed peeling force was good.

-Evaluation standard-

AA: "low-speed peeling force / high-speed peeling force" is 0.30 or more.

A: The "low-speed peeling force / high-speed peeling force" is 0.20 or more and less than 0.30.

B: "Low-speed peeling force / high-speed peeling force" is 0.10 or more and less than 0.20.

C: "Low-speed peeling force / high-speed peeling force" is less than 0.10.

2. Suppression of Zipping Phenomenon

In the above "(2) high-speed peeling force", the presence and degree of the jing sound when the protective film piece (adhesive layer / base material) for peeling force evaluation was peeled from the PET film was confirmed. Then, the inhibition of the jing phenomenon was evaluated according to the following evaluation criteria.

When the evaluation result was "AA", "A" or "B", it was judged that the jinging phenomenon that could occur when peeling at a high speed was sufficiently suppressed.

-Evaluation standard-

AA: There is no sound at all.

A: There is a faint sound.

B: I can hear a little.

C: I can hear a loud sound.

3. Transparency

<Preparation of a protective film for evaluating transparency>

On the polyethylene terephthalate (PET) film [trade name: Cosmoshine (registered trademark) A4100, thickness: 100 μm, manufactured by Toyobo Co., Ltd.] as a base material, the adhesive composition was applied to the coating amount after drying to be 40 g / m 2 to apply a coating film. Formed. Next, the formed coating film was dried at 100 ° C. for 60 seconds using a hot air circulation type dryer to form an adhesive film on the PET film.

Next, the surface treatment surface of the release film [trade name: FilmBiner (registered trademark) 100E-0010N023, thickness: 100 μm, manufactured by Fujimori Industries, Ltd.], the surface of which was exposed with the silicone-based release agent on the exposed side of the adhesive film formed on the PET film. It was superimposed on to obtain a laminate. Transparency evaluation with the laminated structure of the base material / adhesive layer / peeling film by passing the laminate through a pair of pressurized nip rolls, pressing and bonding, and curing the mixture for 96 hours under an atmosphere of 23 ° C. and 50% RH for 96 hours. Dragon protection film was obtained.

The protective film for transparency evaluation produced above was cut to a size of 25 mm × 150 mm to obtain a protective film piece for transparency evaluation. The release film was peeled from the protective film piece for transparency evaluation, and the pressure-sensitive adhesive layer was exposed to provide haze measurement. A haze meter (model number: NDH 5000SP) manufactured by Nippon Denshoku Kogyo Co., Ltd. was used for the measurement of haze.

Based on the measured haze value (unit:%), transparency was evaluated according to the following evaluation criteria.

When the evaluation result was "AA", "A" or "B", it was judged that the transparency was excellent.

-Evaluation standard-

AA: The haze value is less than 1.0%.

A: The haze value is 1.0% or more and less than 1.5%.

B: The haze value is 1.5% or more and less than 2.0%.

C: The haze value is 2.0% or more.

As shown in Table 6 and Table 7, the structural unit derived from n-butylacrylate and the structural unit derived from a monomer having a hydroxyl group are included, the glass transition temperature is -40 ° C or less, and the weight average molecular weight is 20. (Meth) acrylic copolymer (A) (that is, specific (meth) acrylic copolymer (A)) which is in the range of 10,000 to 2 million, and monomers having structural units and hydroxyl groups derived from n-butyl methacrylate A specific (meth) acrylic copolymer (B) [that is, specific, containing the derived structural unit, having a glass transition temperature of 0 ° C to 45 ° C, and a weight average molecular weight of 10,000 to 200,000 or less. (Meth) acrylic copolymer (B)] and an isocyanate-based crosslinking agent, and the content of the specific (meth) acrylic copolymer (B) is 1 part by mass per 100 parts by mass of the specific (meth) acrylic copolymer (A) All of the pressure-sensitive adhesive layers formed from the pressure-sensitive adhesive composition of Examples 1 to 34, which are in the range of not less than 70 parts by mass, have a good balance of low-speed peeling force and high-speed peeling force, and a jeeping phenomenon that may occur when peeling at a high speed. It was confirmed that it was sufficiently suppressed and excellent in transparency.

On the other hand, as shown in Table 8, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 1 does not contain a specific (meth) acrylic copolymer (B), the low-speed peeling force is remarkably low, and the high-speed peeling force is remarkably It was confirmed that the balance between the low-speed peeling power and the high-speed peeling power was not high.

It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 2 in which the (meth) acrylic copolymer (A) does not contain a constituent unit derived from n-butylacrylate has high haze and thus poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 3 in which the (meth) acrylic copolymer (A) does not contain a structural unit derived from a monomer having a hydroxyl group has a high high-speed peeling power, and thus a low-speed peeling power and a high-speed peeling power. It was confirmed that the balance was not good.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 4 in which the glass transition temperature (Tg) of the (meth) acrylic copolymer (A) exceeds -40 ° C is markedly high, resulting in high-speed peeling power and high-speed peeling power. It was confirmed that the balance was not good.

It has been confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 5 in which the weight average molecular weight of the (meth) acrylic copolymer (B) exceeds 200,000 cannot be sufficiently suppressed in the case of peeling at a high speed. . In addition, it was confirmed that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of Comparative Example 5 had a high haze and poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 6 in which the weight average molecular weight of the (meth) acrylic copolymer (B) is less than 10,000 is low in low-speed peeling power, and also high in high-speed peeling power, so that low-speed peeling power and high-speed It was confirmed that the balance of the peeling force was not good.

It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 7 in which the (meth) acrylic copolymer (B) did not contain a constituent unit derived from n-butylmethacrylate was found to have poor haze and poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 8 in which the (meth) acrylic copolymer (B) does not contain a structural unit derived from a monomer having a hydroxyl group has a high high-speed peeling power, and thus a low-speed peeling power and a high-speed peeling power. It was confirmed that the balance was not good.

It does not contain a structural unit derived from n-butyl methacrylate and a structural unit derived from a monomer having a hydroxyl group, and has a glass transition temperature (Tg) of more than 45 ° C and a weight average molecular weight of less than 10,000 (Meta). It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 9 containing the acrylic copolymer (B) was unable to sufficiently suppress the jinging phenomenon that could occur when peeling at a high speed. In addition, it was confirmed that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of Comparative Example 9 had a high haze and poor transparency.

Formed by the pressure-sensitive adhesive composition of Comparative Example 10, which does not contain a structural unit derived from n-butyl methacrylate, and also includes a (meth) acrylic copolymer (B) having a glass transition temperature (Tg) exceeding 45 ° C. It was confirmed that the pressure-sensitive adhesive layer could not sufficiently suppress the jinging phenomenon that may occur when peeling at a high speed. In addition, it was confirmed that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of Comparative Example 10 had a high haze and poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 11 in which the glass transition temperature (Tg) of the (meth) acrylic copolymer (B) exceeds 45 ° C can sufficiently suppress the jinging phenomenon that may occur when peeling at high speed. It was confirmed that there was no. In addition, it was confirmed that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of Comparative Example 11 had a high haze and poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 12 in which the glass transition temperature (Tg) of the (meth) acrylic copolymer (B) is less than 0 ° C. is low in low-speed peeling power, and also high in high-speed peeling power, resulting in low-speed peeling. It was confirmed that the balance between the power and the high-speed peeling force was not good.

When the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 13 in which the content of the specific (meth) acrylic copolymer (B) exceeds 70 parts by mass relative to 100 parts by mass of the specific (meth) acrylic copolymer (A) is peeled at high speed It was confirmed that it was not possible to sufficiently suppress the zipping phenomenon that could occur. In addition, it was confirmed that the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of Comparative Example 13 had a high haze and poor transparency.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 14 in which the content of the specific (meth) acrylic copolymer (B) is less than 1 part by mass relative to 100 parts by mass of the specific (meth) acrylic copolymer (A) is markedly low It was confirmed that the balance between the low-speed peeling force and the high-speed peeling force was not good because of the low and high-speed peeling force.

It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 15, which does not contain an isocyanate-based crosslinking agent, cannot sufficiently suppress the jinging phenomenon that may occur when peeling at high speed.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 16 in which a specific (meth) acrylic copolymer (B) contains an alkylene oxide chain and does not contain a structural unit derived from a monomer having a hydroxyl group has a high-speed peeling power It was confirmed that the balance between the low-speed peeling force and the high-speed peeling force was not high.

Claims (10)

It contains a structural unit derived from n-butyl acrylate and a structural unit derived from a monomer having a hydroxyl group, the glass transition temperature is -40 ° C or less, and the weight average molecular weight is in the range of 200,000 or more and 2,000,000 or less (meta ) Acrylic copolymer (A),
It includes a structural unit derived from n-butyl methacrylate and a structural unit derived from a monomer having a hydroxyl group, and has a glass transition temperature of 0 ° C or more and 45 ° C or less, and a weight average molecular weight of 10,000 or more and 200,000 or less. (Meth) acrylic copolymer (B), which is in the range of,
It contains an isocyanate-based crosslinking agent,
The adhesive composition for optical member protective films whose content of the said (meth) acrylic-type copolymer (B) is 1 mass part or more and 70 mass parts or less with respect to 100 mass parts of said (meth) acrylic-type copolymer (A). The method according to claim 1,
The adhesive composition for an optical member protective film in which the glass transition temperature of the (meth) acrylic copolymer (A) is in the range of -70 ° C to -40 ° C. The method according to claim 1 or claim 2,
Protection of the optical member in which the content ratio of the structural unit derived from the n-butyl methacrylate in the (meth) acrylic copolymer (B) is 50% by mass or more with respect to the total structural unit of the (meth) acrylic copolymer (B) Adhesive composition for films. The method according to claim 1 or claim 2,
Optical member protection film in which the content rate of the structural unit derived from the said n-butylacrylate in the said (meth) acrylic-type copolymer (A) is 50 mass% or more with respect to the whole structural unit of the said (meth) acrylic-type copolymer (A) Pressure-sensitive adhesive composition. The method according to claim 1 or claim 2,
The content ratio of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (A) is 0.7 mass% or more and 15 mass% or less with respect to the total structural unit of the (meth) acrylic copolymer (A). The adhesive composition for optical member protective films which is a range. The method according to claim 1 or claim 2,
The content ratio of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B) is 0.7% by mass or more and 15% by mass or less with respect to all the structural units of the (meth) acrylic copolymer (B). The adhesive composition for optical member protective films which is a range. The method according to claim 1 or claim 2,
The adhesive composition for an optical member protective film in which the content of the (meth) acrylic copolymer (B) is in a range of 3 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic copolymer (A). The method according to claim 1 or claim 2,
The (meth) acrylic copolymer (B), the weight average molecular weight of the adhesive composition for an optical member protective film having a range of 10,000 to 150,000. The method according to claim 1 or claim 2,
The pressure-sensitive adhesive composition for an optical member protective film, wherein the isocyanate-based crosslinking agent is hexamethylene diisocyanate. An optical member protection film comprising a base material and an adhesive layer provided on the base material and further formed by the adhesive composition for an optical member protection film according to claim 1 or 2.