JP2021147590A - Adhesive composition for optical member protective films and optical member protective film - Google Patents

Abstract

To provide an adhesive composition for optical member protective films that can form an adhesive layer striking a balance between low-speed peeling force and high-speed peeling force, and an optical member protective film.SOLUTION: An adhesive composition for optical member protective films has a (meth)acrylic polymer (A) having at least one of a hydroxy group and a carboxy group, and an isocyanate crosslinker (B) having an alkylene oxide chain. The content of the isocyanate crosslinker (B) is 5 pts.mass or more and 15 pts.mass or less relative to 100 pts.mass of the (meth)acrylic polymer (A). There is also provided an optical member protective film.SELECTED DRAWING: None

Description

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 provided with an adhesive layer is widely used. In particular, protective films are often used in various optical members represented by polarizing plates.

For example, Patent Document 1 describes 100 parts by mass of a polymer (A) having a glass transition temperature of less than 0 ° C., a weight average molecular weight of 1000 or more and less than 50,000, and a (meth) acrylic having a glass transition temperature of 30 to 300 ° C. At least one side of the support is provided with a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition containing 0.05 to 3 parts by mass of the system polymer (B) and an organopolysiloxane compound (C) having a specific polyoxyalkylene chain. The surface protective sheet formed in the above is disclosed.

Japanese Unexamined Patent Publication No. 2013-216769

The adhesive composition used for the protective film used for the optical member (hereinafter, also referred to as "adhesive composition for the optical member protective film") is protected after the protective film is attached to the surface of the optical member. While it is necessary, it is required that a pressure-sensitive adhesive layer that can be efficiently peeled off from the optical member can be formed at a stage where problems such as peeling and misalignment from the optical member are unlikely to occur and protection is no longer necessary.
Here, the fact that the adhesive layer is less likely to cause problems such as peeling and slipping from the optical member means that the adhesive force (so-called) measured when the protective film is peeled from the optical member at a low speed (0.3 m / min). , Low speed peeling force). Further, the 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 a high speed (30 m / min).

However, when trying to control the low-speed peeling force and the high-speed peeling force of the pressure-sensitive adhesive layer included in the protective film, both exhibit the same behavior, and it is difficult to adjust the balance between the low-speed peeling force and the high-speed peeling force. Especially in recent years, with the rise of flexible displays, there are increasing opportunities to attach a protective film to a curved surface. When the protective film is attached to a curved surface, problems such as peeling and misalignment from the optical member are more likely to occur than when the protective film is attached to a flat surface. Therefore, the pressure-sensitive adhesive layer provided in the protective film tends to be required to have a higher low-speed peeling force than before. On the other hand, the peeling speed of the protective film from the optical member tends to be higher from the viewpoint of further improving workability. In general, the peeling force of the pressure-sensitive adhesive layer tends to increase as the peeling speed increases. Therefore, when the protective film is peeled from the optical member at a higher speed, the optical member is likely to be damaged. Therefore, the pressure-sensitive adhesive layer provided in the protective film tends to be required to have a lower high-speed peeling force than before.
Therefore, it is more difficult than ever to adjust the balance between the low-speed peeling force and the high-speed peeling force, and an optical member capable of forming an adhesive layer having a good balance between the low-speed peeling force and the high-speed peeling force. It has been difficult to realize a pressure-sensitive adhesive composition for a protective film.

An object to be solved by the present invention is to provide an adhesive composition for an optical member protective film capable of forming an adhesive layer having a good balance between a low-speed peeling force and a high-speed peeling force, and an optical member protective film. ..

Specific means for solving the problem include the following aspects.
<1> With the (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group,
Containing an isocyanate-based cross-linking agent (B) having an alkylene oxide chain,
The content of the isocyanate-based cross-linking agent (B) is in the range of 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (A). Composition.
<2> The pressure-sensitive adhesive composition for an optical member protective film according to <1>, wherein the alkylene oxide chain contained in the isocyanate-based cross-linking agent (B) contains a propylene oxide structure.
<3> The pressure-sensitive adhesive composition for an optical member protective film according to <1> or <2>, wherein the isocyanate-based cross-linking agent (B) is a trifunctional isocyanate compound.
<4> The pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <3>, which contains an antistatic agent.
<5> The pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <4>, which contains a polyether-modified silicone compound.
<6> A base material, a pressure-sensitive adhesive layer provided on the base material and formed by the pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <5>. An optical member protective film comprising.

According to the present invention, there are provided an adhesive composition for an optical member protective film capable of forming an adhesive layer having a good balance between a low-speed peeling force and a high-speed peeling force, and an optical member protective film.

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

The numerical range indicated by using "~" in the present specification means a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. .. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
In the present specification, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, the amount of each component means the total amount of a plurality of kinds of substances when a plurality of kinds of substances corresponding to each component are present, unless otherwise specified.

As used herein, the term "(meth) acrylic polymer" means that the content of structural units derived from a monomer having a (meth) acryloyl group is the total structural unit [that is, (meth) acrylic polymer. It means a polymer which is 50% by mass or more of [all constituent units].
As used herein, the term "(meth) acrylic monomer" means a monomer having a (meth) acryloyl group.

In the present specification, "(meth) acrylic" is a term that includes both "acrylic" and "methacrylic", and "(meth) acrylate" is a term that includes both "acrylate" and "methacrylate". , "(Meta) acryloyl" is a term that includes both "acryloyl" and "methacrylic".

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

As used herein, the term "adhesive composition" means a liquid or paste-like substance before the cross-linking reaction is completed.
As used herein, the term "adhesive layer" means a film made of a substance after the cross-linking reaction in the pressure-sensitive adhesive composition is completed.

As used herein, the term "adhesive body" refers to an optical member.

In the present specification, the "low-speed peeling force" means when the protective film attached to the adherend is peeled 180 ° from the adherend in the longitudinal direction of the protective film at a low speed (that is, 0.3 m / min). Means the adhesive strength measured in. The detailed measurement method is as shown in Examples described later.
In the present specification, the "appropriate low-speed peeling force" means an adhesive force having a strength to such an extent that defects such as peeling and slippage from the adherend are unlikely to occur.

In the present specification, the "high-speed peeling force" is measured when the protective film attached to the adherend is peeled 180 ° from the adherend in the longitudinal direction of the protective film at a high speed (that is, 30 m / min). It means the adhesive strength to be applied. The detailed measurement method is as shown in Examples described later.
In the present specification, the "appropriate high-speed peeling force" means an adhesive force having a strength sufficient to efficiently peel from an adherend.

In the present specification, the "adhesive layer having a good balance between low-speed peeling force and high-speed peeling force" means that problems such as peeling and slippage from the adherend are unlikely to occur, and the adhesive layer is efficiently peeled from the adherend. It means an adhesive layer having an adhesive strength as strong as possible.

[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 “pressure-sensitive adhesive composition”) is a (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group [hereinafter, Also referred to as "specific (meth) acrylic polymer (A)". ] And an isocyanate-based cross-linking agent (B) having an alkylene oxide chain [hereinafter, also referred to as "specific isocyanate-based cross-linking agent (B)". ], And the content of the isocyanate-based cross-linking agent (B) is in the range of 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (A).
According to the pressure-sensitive adhesive composition of the present invention, a pressure-sensitive adhesive layer having a good balance between low-speed peeling force and high-speed peeling force can be formed.
Although it is not clear why the pressure-sensitive adhesive composition of the present invention can exert such an effect, the present inventors speculate as follows. However, the following speculation does not limit the interpretation of the pressure-sensitive adhesive composition of the present invention, but is described as an example.

The pressure-sensitive adhesive composition of the present invention contains a specific (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group, and a specific isocyanate-based cross-linking agent (B) having an alkylene oxide chain. Hereinafter, "hydroxyl group and carboxy group" are also referred to as "hydroxyl group and the like". The hydroxyl groups and the like in the specific (meth) acrylic polymer (A) react with the isocyanate groups in the specific isocyanate-based cross-linking agent (B) to form urethane bonds. Since the specific isocyanate-based cross-linking agent (B) has an alkylene oxide chain, the urethane bond and the alkylene oxide chain coexist at one cross-linking point. Generally, the skeleton containing urethane bonds is hard, and the skeleton containing alkylene oxide chains is soft. Therefore, in the crosslinked structure of the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, a hard skeleton that suppresses wetting on the adherend and a soft skeleton that promotes wetting on the adherend coexist. It is thought that. Further, since the pressure-sensitive adhesive composition of the present invention contains a specific range of the specific isocyanate-based cross-linking agent (B) with respect to the specific (meth) acrylic polymer (A), cross-linking of the pressure-sensitive adhesive layer formed. It is considered that a hard skeleton and a soft skeleton coexist in an appropriate ratio in the structure. Therefore, according to the pressure-sensitive adhesive composition of the present invention, it is presumed that a pressure-sensitive adhesive layer having a good balance between low-speed peeling force and high-speed peeling force can be formed.

Even when the pressure-sensitive adhesive layer is formed by a pressure-sensitive adhesive composition containing a (meth) acrylic polymer having a hydroxyl group or the like and an alkylene oxide chain and an isocyanate-based cross-linking agent having no alkylene oxide chain, cross-linking is also performed. A urethane bond and an alkylene oxide chain are present in the structure. In this case, the urethane bond is concentrated at one cross-linking point and the alkylene oxide chain is dispersed, so that the degree of freedom of the alkylene oxide chain is reduced. It is considered that the skeleton containing the alkylene oxide chain does not show sufficient softness. Therefore, the formed pressure-sensitive adhesive layer is insufficiently wetted with respect to the adherend, and an appropriate low-speed peeling force cannot be obtained (see, for example, Comparative Example 6 described later).

In contrast to the pressure-sensitive adhesive composition of the present invention, in the pressure-sensitive adhesive composition described in Patent Document 1, the high-speed peeling force of the pressure-sensitive adhesive layer is reduced by the organopolysiloxane compound having a polyoxyalkylene chain. Therefore, in the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition described in Patent Document 1, it is considered that not only the high-speed peeling force but also the low-speed peeling force is reduced, and the low-speed peeling force has been required for protective films in recent years. It is presumed that it does not meet the standard.

[Specific (meth) acrylic polymer (A)]
The pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group [that is, a specific (meth) acrylic polymer (A)].
The pressure-sensitive adhesive composition of the present invention may contain only one type of the specific (meth) acrylic polymer (A), or may contain two or more types.

The specific (meth) acrylic polymer (A) may be a homopolymer or a copolymer. Further, the specific (meth) acrylic polymer (A) may be a polymer having only a hydroxyl group among the hydroxyl groups and the carboxy group, or a polymer having only a carboxy group, and the hydroxyl group and the carboxy group may be used. It may be a polymer having both groups.
The specific (meth) acrylic polymer (A) may be, for example, a homopolymer of a (meth) acrylic monomer having at least one of a hydroxyl group and a carboxy group, and has both a hydroxyl group and a carboxy group. A homopolymer of a (meth) acrylic monomer in which at least one of a hydroxyl group and a carboxy group is introduced by substitution may be introduced, and a (meth) acrylic-based single amount having at least one of a hydroxyl group and a carboxy group may be introduced. It may be a polymer of the body, and is a simple substance other than a (meth) acrylic monomer having at least one of a hydroxyl group and a carboxy group and a (meth) acrylic monomer having neither a hydroxyl group nor a carboxy group. It may be a copolymer with a polymer, and it may be a monomer other than a (meth) acrylic monomer having at least one of a hydroxyl group and a carboxy group, and a (meth) acrylic having neither a hydroxyl group nor a carboxy group. It may be a copolymer with a system monomer.
As a preferred embodiment of the specific (meth) acrylic polymer (A), the specific (meth) acrylic polymer (A) is a monomer having a structural unit derived from a monomer having a hydroxyl group and a carboxy group, which will be described later. By including at least one of the constituent units derived from the body, it is an embodiment having at least one of a hydroxyl group and a carboxy group.

<Constituent unit derived from a monomer having a hydroxyl group>
The specific (meth) acrylic polymer (A) preferably contains a structural unit derived from a monomer having a hydroxyl group.
In the present specification, the “constituent 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 monomer having a hydroxyl group is not particularly limited.
Specific examples of the monomer having a hydroxyl group include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl. (Meta) 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-trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (Meta) acrylate, N-hydroxyethyl (meth) acrylamide, glycerin mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate And so on.
As the monomer having a hydroxyl group, a hydroxyalkyl (meth) acrylate is preferable, a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 1 to 5 carbon atoms is more preferable, and a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable. Hydroxyalkyl (meth) acrylates having the above are more preferable, and 4-hydroxybutyl acrylate is particularly preferable.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from a monomer having a hydroxyl group, it may contain only one structural unit derived from the monomer having a hydroxyl group. It may contain more than seeds.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from a monomer having a hydroxyl group, the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic polymer (A) The content of is not particularly limited, but is preferably in the range of 0.1% by mass or more and 10% by mass or less with respect to all the constituent units of the specific (meth) acrylic polymer (A), and is 0. It is more preferably in the range of 5.5% by mass or more and 8% by mass or less, and further preferably in the range of 1% by mass or more and 5% by mass or less.
The content of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic polymer (A) is 0.1 mass by mass with respect to all the structural units of the specific (meth) acrylic polymer (A). % Or more means that the specific (meth) acrylic polymer (A) positively contains a structural unit derived from a monomer having a hydroxyl group.
The content of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic polymer (A) is 10% by mass or less with respect to all the structural units of the specific (meth) acrylic polymer (A). If this is the case, there is a tendency that a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force can be formed.

<Constituent unit derived from a monomer having a carboxy group>
The specific (meth) acrylic polymer (A) preferably contains a structural unit derived from a monomer having a carboxy group.
As used herein, the "constituent unit derived from a monomer having a carboxy group" means a structural unit formed by addition polymerization of a monomer having a carboxy group.

The type of monomer having a carboxy group is not particularly limited.
Specific examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, and ω-carboxy-polycaprolactone mono (meth) acrylate [ For example, ω-carboxy-polycaprolactone (n≈2) monoacrylate], succinic acid ester [for example, 2-acryloyloxyethyl-succinic acid] and the like can be mentioned.
Acrylic acid is preferable as the monomer having a carboxy group.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from a monomer having a carboxy group, it may contain only one structural unit derived from the monomer having a carboxy group. Two or more types may be included.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from a monomer having a carboxy group, it is derived from the monomer having a carboxy group in the specific (meth) acrylic polymer (A). The content of the constituent units is not particularly limited, but is preferably in the range of 0.1% by mass or more and 5% by mass or less with respect to all the constituent units of the specific (meth) acrylic polymer (A). , 0.3% by mass or more and 3% by mass or less, and more preferably 0.5% by mass or more and 1.5% by mass or less.
The content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic polymer (A) is 0.1 with respect to all the structural units of the specific (meth) acrylic polymer (A). The mass% or more means that the specific (meth) acrylic polymer (A) positively contains a structural unit derived from a monomer having a carboxy group.
The content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic polymer (A) is 5% by mass with respect to all the structural units of the specific (meth) acrylic polymer (A). When the following, there is a tendency that a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force can be formed.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer>
The specific (meth) acrylic polymer (A) preferably contains a structural unit derived from the (meth) acrylic acid alkyl ester monomer.
The structural unit derived from the (meth) acrylic acid alkyl ester monomer contributes to the adjustment of the adhesive strength.

In the present specification, the “constituent unit derived from the (meth) acrylic acid alkyl ester monomer” means a structural unit formed by addition polymerization of the (meth) acrylic acid alkyl ester monomer.
The "(meth) acrylic acid alkyl ester monomer" in the present specification does not include a (meth) acrylic acid alkyl ester monomer having at least one of a hydroxyl group and a carboxy group.

The type of the (meth) acrylic acid alkyl ester monomer is not particularly limited.
As the (meth) acrylic acid alkyl ester monomer, an unsubstituted (meth) acrylic acid alkyl ester monomer is preferable.
The alkyl group of the (meth) acrylic acid alkyl ester monomer may be linear, branched or cyclic.
From the viewpoint of adhesive strength, for example, the number of carbon atoms of the alkyl group is preferably in the range of 1 or more and 18 or less, more preferably in the range of 1 or more and 12 or less, and preferably in the range of 1 or more and 8 or less. More preferred.
In particular, when the number of carbon atoms of the alkyl group is in the range of 1 or more and 8 or less, the formed pressure-sensitive adhesive layer tends to appropriately wet and spread with respect to the adherend and exhibit a more appropriate low-speed peeling force.

Specific examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 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, Examples thereof include n-decyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
As the (meth) acrylic acid alkyl ester monomer, at least one selected from n-butyl acrylate and 2-ethylhexyl acrylate is preferable.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from the (meth) acrylic acid alkyl ester monomer, one kind of structural unit derived from the (meth) acrylic acid alkyl ester monomer is used. It may contain only two kinds or more.

When the specific (meth) acrylic polymer (A) contains a structural unit derived from the (meth) acrylic acid alkyl ester monomer, the (meth) acrylic acid alkyl ester in the specific (meth) acrylic polymer (A) The content of the structural unit derived from the monomer is not particularly limited, but is preferably 50% by mass or more, preferably 50% by mass or more, based on all the structural units of the specific (meth) acrylic polymer (A), for example. It is more preferably in the range of mass% or more and 99% by mass or less, further preferably in the range of 60% by mass or more and 99% by mass or less, and particularly preferably in the range of 70% by mass or more and 99% by mass or less.
Here, the content of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic polymer (A) is the total structural unit of the specific (meth) acrylic polymer (A). The content of 50% by mass or more is that the structural unit derived from the (meth) acrylic acid alkyl ester monomer is contained as the main component of the structural unit constituting the specific (meth) acrylic polymer (A). It means that it is.

<Other building blocks>
The specific (meth) acrylic polymer (A) can include structural units (so-called other structural units) other than the above-mentioned structural units within the range in which the effects of the present invention are exhibited.

Examples of the monomer constituting the other structural unit include (meth) acrylate having an aromatic ring represented by benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate and ethoxyethyl. Alkoxyalkyl (meth) acrylate represented by (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and aromatic monovinyl represented by vinyltoluene, acrylonitrile and methacryl. Examples thereof include vinyl cyanide typified by lonitrile, and vinyl esters typified by vinyl acrylate, vinyl acetate, vinyl propionate, and vinyl versatic acid. In addition, various derivatives of these monomers can be mentioned.

When the specific (meth) acrylic polymer (A) contains other structural units, it may contain only one type of other structural units, or may contain two or more types of other structural units.

When the specific (meth) acrylic polymer (A) contains other structural units, the content of the other structural units in the specific (meth) acrylic polymer (A) is not particularly limited and depends on the purpose. , Can be set as appropriate.

<< Glass transition temperature of specific (meth) acrylic polymer (A) >>
The glass transition temperature (also referred to as “Tg”) of the specific (meth) acrylic polymer (A) is not particularly limited, but is preferably −40 ° C. or lower, preferably −45 ° C. or lower, for example. More preferably, it is more preferably −50 ° C. or lower.
When the glass transition temperature of the specific (meth) acrylic polymer (A) is −40 ° C. or lower, there is a tendency that a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force can be formed.
The lower limit of the glass transition temperature of the specific (meth) acrylic polymer (A) is not particularly limited, but is preferably −70 ° C. or higher, for example.

The glass transition temperature of the specific (meth) acrylic polymer (A) is the absolute temperature (unit: K; hereinafter the same) calculated from the following formula 1 as the Celsius temperature (unit: ° C; hereinafter the same). ) Is the value converted.
1 / Tg = m1 / Tg1 + m2 / Tg2 + ... + m (k-1) / Tg (k-1) + mk / Tgk (Equation 1)

In the formula 1, Tg1, Tg2, ..., Tg (k-1), and Tgk are absolute when each monomer constituting the specific (meth) acrylic polymer (A) is used as a homopolymer. Each represents the glass transition temperature represented by the temperature. m1, m2, ..., M (k-1), and mk represent the mole fractions of each monomer constituting the specific (meth) acrylic polymer (A), and m1 + m2 + ... + m. (k-1) + mk = 1.
The absolute temperature can be converted to the Celsius temperature by subtracting 273 from the absolute temperature, and the Celsius temperature can be converted to the absolute temperature by adding 273 to the Celsius temperature.

In the present specification, the "glass transition temperature represented by the absolute temperature when made into a homopolymer" is the glass transition represented by the absolute temperature of the homopolymer produced by polymerizing the monomer alone. Refers to temperature.
The glass transition temperature of the homopolymer was measured using a differential scanning calorimetry device (DSC) [model number: EXSTAR6000, Seiko Instruments Co., Ltd.] under the conditions of a measurement sample of 10 mg and a temperature rise rate of 10 ° C./min in a nitrogen stream. The measured and obtained bending point of the DSC curve is taken as the glass transition temperature of the homopolymer.

The "glass transition temperature represented by the Celsius temperature when made into a homopolymer" of a typical monomer is -76 ° C for 2-ethylhexyl acrylate (2EHA) and -10 ° C for 2-ethylhexyl methacrylate (2EHMA). , N-butyl acrylate (n-BA) at −57 ° C., n-butyl methacrylate (n-BMA) at 21 ° C., t-butyl acrylate (t-BA) at 41 ° C., 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, isobonyl methacrylate (IBXMA) is 155 ° C, and isobonyl acrylate (IBXA). ) Is 96 ° C, ethyl acrylate (EA) is -27 ° C, methacrylic acid is 185 ° C, 4-hydroxybutyl acrylate (4HBA) is -39 ° C, 2-hydroxyethyl acrylate (2HEA) is -15 ° C, 2-hydroxy. Ethyl methacrylate (2HEMA) at 55 ° C, 2-hydroxypropyl acrylate (2HPA) at -7 ° C, acrylic acid (AA) at 163 ° C, i-octyl acrylate (i-OA) at -75 ° C, dimethylaminoethyl methacrylate ( DM) at 18 ° C, ω-carboxy-polycaprolactone (n≈2) monoacrylate at -30 ° C, polypropylene glycol monomethacrylate (PPGMA) at -62 ° C, and 2-acryloyloxyethyl-succinic acid at -40 ° C. be.

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

<< Weight average molecular weight of specific (meth) acrylic polymer (A) >>
The weight average molecular weight (also referred to as "Mw") of the specific (meth) acrylic polymer (A) is preferably in the range of more than 200,000 and not more than 2 million, and more than 200,000 and not more than 1.8 million. It is more preferably in the range, more preferably in the range of more than 200,000 and not more than 1.5 million, and further preferably in the range of more than 200,000 and not more than 1.2 million.
When the weight average molecular weight of the specific (meth) acrylic polymer (A) is within the above range, the wettability to the adherend becomes appropriate, and the extreme decrease in the low-speed peeling force and the extreme increase in the high-speed peeling force are further suppressed. Will be done. Therefore, there is a tendency that a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force can be formed.

The weight average molecular weight of the specific (meth) acrylic polymer (A) is a value measured by the following method. Specifically, the measurement is performed according to the following (1) to (3).
(1) A solution of the specific (meth) acrylic polymer (A) is applied to a release paper and dried at 100 ° C. for 1 minute to obtain a film-like specific (meth) acrylic polymer (A).
(2) A sample solution having a solid content concentration of 0.2% by mass is obtained by using the film-shaped specific (meth) acrylic polymer (A) obtained in (1) above and tetrahydrofuran. The "solid content concentration" here means the mass ratio of the specific (meth) acrylic polymer (A) to the sample solution.
(3) Using gel permeation chromatography (GPC), the weight average molecular weight of the specific (meth) acrylic polymer (A) is measured as a standard polystyrene-equivalent value under the following conditions.

~conditions~
Measuring device: High-speed GPC [Model number: HLC-8220 GPC, Tosoh Corporation]
Detector: Differential Refractometer (RI) [Built-in to HLC-8220, Tosoh Corporation]
Column: TSK-GEL GMHXL [Tosoh Co., Ltd.] connected in series 4 Column temperature: 40 ° C
Eluent: Tetrahydrofuran Sample solution injection volume: 100 μL
Flow rate: 0.8 mL / min

The weight average molecular weight of the specific (meth) acrylic polymer (A) is desired by adjusting the polymerization temperature, polymerization time, amount of organic solvent used, type of polymerization initiator, amount of polymerization initiator used, and the like. Can be a value.

<< Hydroxyl value of specific (meth) acrylic polymer (A) >>
When the specific (meth) acrylic polymer (A) has a hydroxyl group, the hydroxyl value of the specific (meth) acrylic polymer (A) is not particularly limited, but is, for example, 0.3 mgKOH / g or more and 40 mgKOH / g or less. It is preferably in the range of 0.5 mgKOH / g or more and 30 mgKOH / g or less, and further preferably in the range of 1 mgKOH / g or more and 20 mgKOH / g or less.
When the hydroxyl value of the specific (meth) acrylic polymer (A) is within the above range, a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force tends to be formed.

The hydroxyl value of the specific (meth) acrylic polymer (A) is a value obtained by the following formula. In the following calculation formula, 56.1 is the molecular weight of KOH.
Hydroxy group value (mgKOH / g)
= {(A1 / 100) ÷ A2} × 56.1 × 1000 × A3
A1: Ratio (unit: mass%) of the monomer having a hydroxyl group to all the monomers used in the production of the specific (meth) acrylic polymer (A).
A2: Molecular weight of the monomer having a hydroxyl group used for producing the specific (meth) acrylic polymer (A) A3: Monomer having a hydroxyl group The number of hydroxyl groups contained in one molecule

When there are two or more types of monomers having hydroxyl groups used in the production of the specific (meth) acrylic polymer (A), determine the hydroxyl value of each monomer according to the above formula. After that, the obtained values are totaled to obtain the hydroxyl value.

<< Acid value of specific (meth) acrylic polymer (A) >>
When the specific (meth) acrylic polymer (A) has a carboxy group, the acid value of the specific (meth) acrylic polymer (A) is not particularly limited, but is, for example, 0.7 mgKOH / g or more and 24 mgKOH / g. The range is preferably as follows, more preferably 1 mgKOH / g or more and 20 mgKOH / g or less, and further preferably 2 mgKOH / g or more and 10 mgKOH / g or less.
When the acid value of the specific (meth) acrylic polymer (A) is within the above range, a pressure-sensitive adhesive layer having a better balance between the low-speed peeling force and the high-speed peeling force tends to be formed.

The acid value of the specific (meth) acrylic polymer (A) is a value obtained by the following formula. In the following calculation formula, 56.1 is the molecular weight of KOH.
Acid value (mgKOH / g)
= {(A1 / 100) ÷ a2} × 56.1 × 1000 × a3
a1: Ratio (unit: mass%) of the monomer having a carboxy group in all the monomers used for producing the specific (meth) acrylic polymer (A).
a2: Molecular weight of the monomer having a carboxy group used for producing the specific (meth) acrylic polymer (A) a3: Number of carboxy groups contained in one monomer having a carboxy group

When there are two or more types of monomers having a carboxy group used in the production of the specific (meth) acrylic polymer (A), the acid value of each monomer is determined according to the above formula. After the calculation, the obtained values are summed to obtain the acid value.

<< Content of specific (meth) acrylic polymer (A) >>
The content of the specific (meth) acrylic polymer (A) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, but is, for example, 75.0% by mass or more with respect to the total solid content in the pressure-sensitive adhesive composition. It is preferably in the range of 95.2% by mass or less, more preferably in the range of 80.0% by mass or more and 95.0% by mass or less, and in the range of 85.0% by mass or more and 95.0% by mass or less. It is more preferable that there is, and it is particularly preferable that it is in the range of 90.0% by mass or more and 95.0% by mass or less.
In the present specification, the "total solid content in the pressure-sensitive adhesive composition" means the total mass of the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition does not contain a solvent, and the pressure-sensitive adhesive composition contains a solvent. When included, it means the mass of the residue obtained by removing the solvent from the pressure-sensitive adhesive composition.

<< Manufacturing method of specific (meth) acrylic polymer (A) >>
The method for producing the specific (meth) acrylic polymer (A) is not particularly limited.
The specific (meth) acrylic polymer (A) polymerizes the above-mentioned monomers by a known polymerization method typified by, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a massive polymerization method. Can be manufactured by The specific (meth) acrylic polymer (A) is a known polymerization method typified by, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method, and is either a hydroxyl group or a carboxy group. It can be produced by producing a (meth) acrylic polymer by polymerizing a monomer having no such substance, and then introducing at least one of a hydroxyl group and a carboxy group into the produced (meth) acrylic polymer by substitution. ..
As the polymerization method, the solution polymerization method is preferable because the treatment step is relatively simple and can be performed in a short time in preparing the pressure-sensitive adhesive composition of the present invention after production.

In the solution polymerization method, generally, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent used as needed are charged in a polymerization tank, and the mixture is stirred in a nitrogen stream at the reflux temperature of the organic solvent. While heating for several hours. In this case, at least a part of the organic solvent, the monomer, the polymerization initiator and / or the chain transfer agent may be added sequentially.

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, alcohol compounds and the like.
More specifically, examples of the organic solvent used in the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetraline, and decalin. And aromatic hydrocarbon compounds typified by aromatic naphtha, n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and fat typified by terepine oil. Represented by group or alicyclic hydrocarbon compounds, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate. Estel compounds, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, and ketone compounds typified by methylcyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Glycol ether compounds typified by ether and diethylene glycol monobutyl ether, as well as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t- Examples thereof include alcohol compounds typified by butyl alcohol.

In the production of the specific (meth) acrylic polymer (A), it is preferable to use an organic solvent that does not easily cause chain transfer during the polymerization reaction of the aromatic hydrocarbon compound, ester compound, ketone compound and the like, and in particular, the specific (meth) acrylic polymer (meth) is produced. ) From the viewpoint of the solubility of the acrylic polymer (A), the ease of the polymerization reaction, and the like, it is preferable to use at least one selected from the group consisting of ethyl acetate, toluene, and methyl ethyl ketone.

At the time of the polymerization reaction, only one kind of organic solvent may be used, or two or more kinds may be used.

Examples of the polymerization initiator include organic peroxides and azo compounds used in ordinary solution polymerization methods.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, and di-2-ethylhexylperoxydi. Carbonate, t-butylperoxypivalate, 2,2-bis (4,5-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,5-di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,5-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,54-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4) Examples include -di-t-butylperoxycyclohexyl) butane and 2,2-bis (4,5-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.
In the production of the specific (meth) acrylic polymer (A), it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and particularly preferably an azo compound.

At the time of the polymerization reaction, only one kind of polymerization initiator may be used, or two or more kinds of polymerization initiators may be used.

The amount of the polymerization initiator used is not particularly limited, and can be appropriately set, for example, according to the molecular weight of the target specific (meth) acrylic polymer (A).

A chain transfer agent may be used in the production of the specific (meth) acrylic polymer (A), if necessary.
Examples of the chain transfer agent include cyanoacetic acid, an alkyl ester compound having 1 to 8 carbon atoms of cyanoacetic acid, bromoacetic acid, an alkyl ester compound having 1 to 8 carbon atoms of bromoacetic acid, α-methylstyrene, anthracene, phenanthrene, and fluorene. , And aromatic compounds such as 9-phenylfluorene, p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and aromatic nitro compounds such as p-nitrotoluene, benzoquinone and A benzoquinone derivative typified by 2,3,5,6-tetramethyl-p-benzoquinone, a borane derivative typified by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane. , Tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, and halogenated hydrocarbon compounds typified by 3-chloro-1-propene, aldehyde compounds typified by chloral and furaldehyde, alkyl having 1 to 18 carbon atoms. For mercaptan compounds, aromatic mercaptan compounds typified by thiophenol and toluene mercaptan, mercaptoacetic acid, alkyl ester compounds having 1 to 10 carbon atoms of mercaptoacetic acid, hydroxyalkyl mercaptan compounds having 1 to 12 carbon atoms, and pinen and turpinolene. A typical terpen compound can be mentioned.

When a chain transfer agent is used in the production of the specific (meth) acrylic polymer (A), the amount of the chain transfer agent used is not particularly limited, and for example, the target specific (meth) acrylic polymer (A) is used. ) Can be appropriately set according to the molecular weight.

The polymerization temperature is not particularly limited, and can be appropriately set, for example, according to the molecular weight of the target specific (meth) acrylic polymer (A).

[Specific isocyanate-based cross-linking agent (B)]
The pressure-sensitive adhesive composition of the present invention contains an isocyanate-based cross-linking agent (B) having an alkylene oxide chain [that is, a specific isocyanate-based cross-linking agent (B)]. The content of the specific isocyanate-based cross-linking agent (B) in the pressure-sensitive adhesive composition of the present invention is 5 parts by mass or more and 15 parts by mass with respect to 100 parts by mass of the above-mentioned specific (meth) acrylic polymer (A). It is in the range of less than a part.

As used herein, the term "isocyanate-based cross-linking agent" refers to a compound having two or more isocyanate groups in the molecule (so-called polyisocyanate compound).

The specific isocyanate-based cross-linking agent (B) is not particularly limited as long as it has an alkylene oxide chain.
The alkylene oxide chain contained in the specific isocyanate-based cross-linking agent (B) is not particularly limited, and may contain, for example, an ethylene oxide structure, a propylene oxide structure, or a butylene oxide structure. good.
For example, the alkylene oxide chain of the specific isocyanate-based cross-linking agent (B) preferably contains a propylene oxide structure from the viewpoint of easily forming a pressure-sensitive adhesive layer exhibiting a moderately high low-speed peeling force.

The number of repeating units of the alkylene oxide chain is not particularly limited.
The number of repeating units of the alkylene oxide chain may be, for example, 2 to 100.
As used herein, the "repeating unit number" of an alkylene oxide chain means the "average number of moles of substance added" of the alkylene oxide chain. The "number of repeating units" of the alkylene oxide chain means the number of each of the alkylene oxide chains when a plurality of alkylene oxide chains are present.

The specific isocyanate-based cross-linking agent (B) may be a bifunctional isocyanate compound or a trifunctional or higher functional isocyanate compound.
The trifunctional or higher functional isocyanate compound may be an adduct-type isocyanate compound, an isocyanurate-type isocyanate compound, or a biuret-type isocyanate compound.
As the specific isocyanate-based cross-linking agent (B), a trifunctional isocyanate compound is preferable, and an adduct-type isocyanate compound is more preferable.
As used herein, the term "trifunctional isocyanate compound" means a compound having three isocyanate groups in the molecule.

The molecular weight of the specific isocyanate-based cross-linking agent (B) is not particularly limited, but is preferably in the range of 150 or more and 50,000 or less, and more preferably 400 or more and 30,000 or less.

Examples of the specific isocyanate-based cross-linking agent (B) include an adduct of an isocyanate compound containing a structure derived from hexamethylene diisocyanate (HMDI) and an alkylene oxide structure, and a structure derived from isocyanatomethylcyclohexane and an alkylene oxide structure. Adduct of an isocyanate compound containing, an adduct of an isocyanate compound containing a structure derived from tolylene diisocyanate (TDI) and an alkylene oxide structure, an isocyanate compound containing a structure derived from hexamethylene diisocyanate (HMDI) and an alkylene oxide structure. Examples thereof include an isocyanurate form, a bullet form of an isocyanate compound containing a structure derived from hexamethylene diisocyanate (HMDI) and an alkylene oxide structure.
Examples of the specific isocyanate-based cross-linking agent (B) include an adduct compound of an isocyanate compound containing a structure derived from hexamethylene diisocyanate (HMDI) and an alkylene oxide structure, and a structure derived from isocyanatomethylcyclohexane and an alkylene oxide structure. At least one selected from the group consisting of adducts of isocyanate compounds containing is preferable.

As the specific isocyanate-based cross-linking agent (B), a commercially available product can be used.
As an example of a commercially available product of the specific isocyanate-based cross-linking agent (B), an adduct of an isocyanate compound containing a structure derived from Takenate (registered trademark) M631N [trade name, hexamethylene diisocyanate (HMDI) and a propylene oxide structure, 3 Functional isocyanate compound, Mitsui Kagaku Co., Ltd.], Takenate (registered trademark) M605NE [trade name, isocyanatomethylcyclohexane-derived structure and propylene oxide structure-containing isocyanate compound adduct, trifunctional isocyanate compound, Mitsui Chemical Co., Ltd.] and the like.

The pressure-sensitive adhesive composition of the present invention may contain only one type of the specific isocyanate-based cross-linking agent (B), or may contain two or more types.

The content of the specific isocyanate-based cross-linking agent (B) in the pressure-sensitive adhesive composition of the present invention is in the range of 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). Yes, it is preferably in the range of 5 parts by mass or more and 12 parts by mass or less, more preferably in the range of 5 parts by mass or more and 10 parts by mass or less, and further preferably in the range of 7 parts by mass or more and 10 parts by mass or less. preferable.
When the content of the specific isocyanate-based cross-linking agent (B) in the pressure-sensitive adhesive composition of the present invention is 5 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic polymer (A), the pressure-sensitive adhesive is formed. The agent layer does not have an excessively high high-speed peeling force, and tends to have a better balance between the low-speed peeling force and the high-speed peeling force.
A pressure-sensitive adhesive formed when the content of the isocyanate-based cross-linking agent (C) in the pressure-sensitive adhesive composition of the present invention is 15 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). The layer tends to have a better balance between the low speed peeling force and the high speed peeling force without the low speed peeling force being excessively low.

[Organic solvent]
The pressure-sensitive adhesive composition of the present invention may contain an organic solvent.
When the pressure-sensitive adhesive composition of the present invention contains an organic solvent, the coatability can be improved.
Examples of the organic solvent include the same organic solvents as those used in the polymerization reaction of the specific (meth) acrylic polymer (A) described above.

When the pressure-sensitive adhesive composition of the present invention contains an organic solvent, it may contain only one type of organic solvent, or may contain two or more types of organic solvent.

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 intended purpose.

[Antistatic agent]
The pressure-sensitive adhesive composition of the present invention may contain an antistatic agent.
The antistatic agent is not particularly limited, and examples thereof include an ionic compound.
Examples of the ionic compound include alkali metal salts and organic salts.
Among these, an alkali metal salt is preferable as the ionic compound.
The alkali metal salt is not particularly limited as long as it is a metal salt having ^{lithium ion (Li +} ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium ion (Rb ^{+) or the like as cations.}
Alkali metal ^salt, a Li +, Na ^+, and at least one cation selected from the group consisting of ^{K +, Cl -, 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 ⁻ It is preferably a metal salt composed of at least one anion selected from the above, preferably LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ (so-called LiTFS), Li (FSO). ₂ ) _{Lithium salts such as 2} N, Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C are more preferable, and LiClO ₄ , At least one lithium salt selected from the group consisting of _{LiCF 3} SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and Li (CF ₃ SO ₂ ) _{3 C.} It is more preferable to have.

When the pressure-sensitive adhesive composition of the present invention contains an antistatic agent, it may contain only one type of antistatic agent, or may contain two or more types of antistatic agent.

When the pressure-sensitive adhesive composition of the present invention contains an antistatic agent, the content of the antistatic agent is not particularly limited and can be appropriately set according to the intended purpose.
The content of the antistatic agent in the pressure-sensitive adhesive composition of the present invention is, for example, in the range of 0.01 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). Is preferable.

[Polyether-modified silicone compound]
The pressure-sensitive adhesive composition of the present invention may contain a polyether-modified silicone compound.
In the pressure-sensitive adhesive composition of the present invention, the polyether-modified silicone compound can function as a release modifier.
The polyether-modified silicone compound is not particularly limited, but for example, it has a silicone compound in which an alkylene oxide structure having a hydroxyl group at the end is bonded to a part of a side chain of a polysiloxane chain which is a main chain, and an acetyl group at the end. At least one silicone compound selected from the group consisting of a silicone compound having an alkylene oxide structure bonded and a silicone compound having an alkylene oxide structure bonded to both ends of a polysiloxane chain which is a main chain [hereinafter, , Also referred to as "specific polyether-modified silicone compound". ] Is preferable.

The specific polyether-modified silicone compound is preferably a polysiloxane compound containing a structural unit derived from a dialkylsiloxane and a structural unit derived from an alkylsiloxane having an alkylene oxide structure having a hydroxyl group at the terminal bonded thereto.
The number of carbon atoms of the alkyl group in the dialkylsiloxane is preferably 1 to 4, and more preferably 1.
The carbon number of the alkylene oxide chain in the alkylsiloxane to which the alkylene oxide structure having a hydroxyl group at the terminal is bonded is preferably 2 to 4, more preferably 2 or 3.
The number of carbon atoms of the alkyl group in the alkylsiloxane to which the alkylene oxide structure having a hydroxyl group at the terminal is bonded is preferably 1 to 4.
The content of the alkylene oxide chain in the alkylsiloxane to which the alkylene oxide structure having a hydroxyl group at the terminal is bonded is preferably 1 to 100, more preferably 10 to 100.

When the specific polyether-modified silicone compound contains a structural unit derived from dialkylsiloxane and a structural unit derived from alkylsiloxane having an alkylene oxide structure having a hydroxyl group at the terminal bonded, the content of the structural unit derived from dialkylsiloxane. Is preferably 100 or less, and more preferably 1 to 80.
Further, the content of the structural unit derived from the alkylsiloxane having the alkylene oxide structure having a hydroxyl group at the terminal bonded is preferably 2 to 100, more preferably 2 to 80.

As the specific polyether-modified silicone compound, a compound represented by the following formula (A) or formula (B) is preferable.

In the formula (A), p is the number of repetitions of the dimethylsiloxane structural unit, which represents an integer of 0 to 100, and q is the number of repetitions of the methylpropylenesiloxane structural unit having a polyethylene oxide chain, which is 2 to 2. It represents an integer of 100, where a is the number of iterations of the ethyleneoxide structural unit and represents an integer of 1-100.
When the compound represented by the formula (A) is an aggregate of a plurality of compounds, p, q, and a are average values as an aggregate of the compounds and are rational numbers.

In the formula (A), the number of repetitions of the ethylene oxide structural unit represented by a is preferably an integer of 10 to 100.
In the formula (A), the number of repetitions of the dimethylsiloxane structural unit represented by p is preferably an integer of 1 to 80.
In the formula (A), the number of repetitions of the methylpropylene siloxane structural unit represented by q is preferably an integer of 2 to 80.

As the compound represented by the formula (A), a commercially available product can be used.
Examples of commercially available products of the compound represented by the formula (A) include "DOWNSIL (registered trademark) SF-8428", "DOWNSIL (registered trademark) FZ-2162", "DOWNSIL (registered trademark) SH-3773M", "DOWNSIL® FZ-77", "DOWNSIL® FZ-2104", "DOWNSIL® FZ-2110", "DOWNSIL® L-7001", "DOWNSIL®""L-7002","DOWNSIL (registered trademark) SH-3479", etc. [above, Dow Toray Co., Ltd.] can be mentioned.

In the formula (B), R ¹ and R ² independently represent an alkylene group having 1 to 6 carbon atoms, and c is a repetition number of a dimethylsiloxane structural unit and represents an integer of 10 to 80. d is the number of repetitions of the ethylene oxide structural unit and represents an integer of 1 or more, e is the number of repetitions of the propylene oxide structural unit and represents an integer of 0 or more, and d + e is an integer of 1 to 30. show. The order of the ethylene oxide structural units and the propylene oxide structural units may be random.

As the compound represented by the formula (B), a commercially available product can be used.
Examples of commercially available compounds represented by the formula (B) include "DOWNSIL (registered trademark) BY-16-201" and "DOWNSIL (registered trademark) SF-8427" [above, Dow Toray Industries, Inc. Toray Dow Corning Co., Ltd.] can be mentioned.

The weight average molecular weight of the polyether-modified silicone compound is not particularly limited, but is preferably in the range of 10,000 or more and 20,000 or less, and preferably in the range of 3,000 or more and 15,000 or less. More preferred.
The weight average molecular weight of the polyether-modified silicone compound is a value measured by the same method as the method for measuring the weight average molecular weight of the specific (meth) acrylic polymer (A) described above.

When the pressure-sensitive adhesive composition of the present invention contains a polyether-modified silicone compound, it may contain only one type of the polyether-modified silicone compound, or may contain two or more types.

When the pressure-sensitive adhesive composition of the present invention contains a polyether-modified silicone compound, the content of the polyether-modified silicone compound is not particularly limited and can be appropriately set depending on the intended purpose.
The content of the polyether-modified silicone compound in the pressure-sensitive adhesive composition of the present invention is, for example, 0.1 part by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). It is preferably in the range of 0.1 parts by mass or more and 1.5 parts by mass or less, and further preferably in the range of 0.1 parts by mass or more and 1.0 parts by mass or less.

[Crosslink catalyst]
The pressure-sensitive adhesive composition of the present invention may contain a cross-linking catalyst.
The cross-linking catalyst is not particularly limited, and known ones can be used.
Examples of the cross-linking catalyst include organometallic compounds represented by dioctyltin dilaurate (DOTDL) and 1,3-diacetoxytetrabutylstanoxane, and tertiary amines represented by triethylenediamine and N-methylmorpholine. Examples include compounds.

When the pressure-sensitive adhesive composition of the present invention contains a cross-linking catalyst, it may contain only one type of cross-linking catalyst, or may contain two or more types of cross-linking catalysts.

When the pressure-sensitive adhesive composition of the present invention contains a cross-linking catalyst, the content of the cross-linking catalyst is not particularly limited and can be appropriately set depending on the intended purpose.

[Other ingredients]
The pressure-sensitive adhesive composition of the present invention may contain components other than the above-mentioned components (so-called other components), if necessary, as long as the effects of the present invention are not impaired.
Other components include polymers other than the specific (meth) acrylic polymer (A) and cross-linking agents other than the specific isocyanate-based cross-linking agent (B) [for example, an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B). Cross-linking agents and metal chelate-based cross-linking agents], antioxidants, colorants (for example, dyes and pigments), light stabilizers (for example, ultraviolet absorbers) and the like.

When the pressure-sensitive adhesive composition of the present invention contains other components, the content of the other components can be appropriately set as long as the effects of the present invention are exhibited.

[Use]
The pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer having a good balance between low-speed peeling force and high-speed peeling force, in other words, after being attached to the surface of an adherend, while protection is required. In order to protect the optical member, it is difficult for problems such as peeling and slipping from the adherend to occur, and protection is not required. When peeling from the adherend, an adhesive layer that can be peeled off efficiently can be formed. It is preferably used for the film (so-called optical member protective film). That is, the pressure-sensitive adhesive composition of the present invention is suitable for use in attaching a protective film to an optical member.

The optical member is not particularly limited, and examples thereof include a member constituting a device (so-called optical device) such as an image display device and an input device, or a member used for these devices.
Specific examples of the optical member include a polarizing plate, an AG (Anti-Glare) polarizing plate, a wave plate, a retardation plate including a wave plate such as 1/2 and 1/4, a viewing angle compensation film, an optical compensation film, and brightness improvement. Examples thereof include a film, a light guide plate, a reflective film, an antireflection film, a transparent conductive film such as an ITO (Indium-Tin Oxide) film, a prism sheet, a lens sheet, and a diffusing plate.
As the material of the optical member, polyethylene resin, polyester resin, acetate resin (for example, triacetyl cellulose resin), polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, etc. Examples thereof include acrylic resins, vinyl chloride resins, ABS (Acrylonitrile Butadiene Styrene) resins, and fluororesins.

[Optical member protective film]
The optical member protective film of the present invention (hereinafter, also simply referred to as “protective film”) is a pressure-sensitive adhesive provided on a base material and the above-mentioned pressure-sensitive adhesive composition of the present invention. It comprises an agent layer. That is, in the protective film of the present invention, the base material and the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention are laminated.
Since the protective film of the present invention includes the pressure-sensitive adhesive layer formed by 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. In other words, after the protective film of the present invention is attached to the surface of the adherend, while protection is required, problems such as peeling and slippage from the adherend are unlikely to occur, and protection is not required. When peeling from the adherend, it can be peeled efficiently.

The base material is not particularly limited as long as the pressure-sensitive adhesive layer can be formed on the base material.
Examples of the base material include polyethylene-based resin, polyester-based resin, acetate-based resin (for example, triacetyl cellulose resin), polyether sulfone-based resin, polycarbonate-based resin, polyamide-based resin, polyimide-based resin, and polyolefin-based resin. Examples thereof include films containing resins such as acrylic resins, vinyl chloride resins, ABS (Acrylonitrile Butadiene Styrene) resins, and fluororesins.
For example, from the viewpoint of inspection and management of optical members by fluoroscopy, as the base material, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin , And a film containing at least one resin selected from the group consisting of acrylic resins is preferable.
Further, for example, from the viewpoint of surface protection performance, a film containing a polyester resin is preferable, and from the viewpoint of practicality, a film containing polyethylene terephthalate (PET) is particularly preferable.

The substrate may contain various additives such as plasticizers, colorants (eg, dyes and pigments), heat stabilizers, light stabilizers, antistatic agents, flame retardants, antioxidants and the like.
The base material may be partially or wholly patterned.

The thickness of the base material is not particularly limited, but 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, for example, preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of the strength of the protective film.

An antistatic layer may be provided on one side or both sides of the base material. Further, even if the surface on the side where the pressure-sensitive adhesive layer of the base material is provided is subjected to surface treatment such as corona discharge treatment or plasma discharge treatment from the viewpoint of improving the adhesion between the base material and the pressure-sensitive adhesive layer. good.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and a commonly used method can be adopted.
As a 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 substrate as it is or diluted with a solvent if necessary to form a coating film. Next, the formed coating film is dried to form an adhesive film on the substrate. Next, the pressure-sensitive adhesive film formed on the base material is cured to form a pressure-sensitive adhesive layer on the base material.

In the protective film of the present invention, the exposed pressure-sensitive adhesive layer may be protected by a release film. The release film is not particularly limited as long as it can be easily peeled from the pressure-sensitive adhesive layer. For example, a resin film having one or both sides surface-treated with a release treatment agent (so-called easy peeling treatment). Can be mentioned. Examples of the resin film include a polyester film typified by a polyethylene terephthalate (PET) film. Examples of the stripping agent include fluororesins, paraffin waxes, silicones, long-chain alkyl group compounds and the like.
The release film protects the surface of the pressure-sensitive adhesive layer until the protective film is put into practical use, and is peeled off at the time of use.

As another method for forming the pressure-sensitive adhesive layer on the substrate, for example, the following method can be adopted.
The pressure-sensitive adhesive composition of the present invention is applied as it is or, if necessary, diluted with a solvent on a release film such as a paper or resin film that has been surface-treated with a release agent to remove the pressure-sensitive adhesive composition. A coating film is formed on the film. Next, the formed coating film is dried to form an adhesive film on the release film. Next, the exposed surface of the formed pressure-sensitive adhesive film is brought into contact with the base material and pressurized, and the pressure-sensitive adhesive film is transferred to the base material to form the pressure-sensitive adhesive film on the base material. Next, the formed adhesive film is cured to form an adhesive layer on the base material.

The method of applying the pressure-sensitive adhesive composition on the substrate or the release film is not particularly limited, and for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a knife coater, a spray coater, and a bar. A known method using a coater, an applicator, or the like can be mentioned.
The amount of the pressure-sensitive adhesive composition applied onto the base material or the release film is appropriately set according to 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 strength required for the protective film, the type of adherend (for example, material and shape), the surface roughness of the adherend, and the like.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is generally in the range of 1 μm or more and 100 μm or less, preferably in the range of 5 μm or more and 50 μm or less, and more preferably in the range of 10 μm or more and 30 μm or less.

The method for drying the coating film formed on the base material or 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 according to the thickness of the coating film, the amount of the organic solvent in the coating film, and the like.
An example of the drying condition is a condition of drying at 70 ° C. to 120 ° C. for 1 minute to 3 minutes using a hot air dryer.

Curing is performed, for example, in an environment of 20 ° C. to 35 ° C. for 4 to 7 days.
Curing completes the cross-linking reaction of the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive layer.

The adhesive force (so-called peeling force) of the adhesive layer when the protective film attached to the adherend is peeled 180 ° is 0 when the peeling speed is 0.3 m / min (that is, low-speed peeling). It is preferably .07N / 25mm or more, more preferably 0.10N / 25mm or more, and even more preferably 0.15N / 25mm or more.

The adhesive force (so-called peeling force) of the adhesive layer when the protective film attached to the adherend is peeled 180 ° is 1.00 N when the peeling speed is 30 m / min (that is, high-speed peeling). It is preferably less than / 25 mm, more preferably less than 0.80 N / 25 mm, and even more preferably less than 0.70 N / 25 mm.

In the present specification, a pressure-sensitive adhesive layer having a good balance between low-speed peeling force and high-speed peeling force is a value obtained by dividing the value of low-speed peeling force by the value of high-speed peeling force (that is, "low-speed peeling force / high-speed peeling force / high speed"). Evaluate based on "peeling force").
The "low-speed peeling force / high-speed peeling force" is preferably 0.10 or more, more preferably 0.15 or more, and further preferably 0.20 or more.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Manufacture of (meth) acrylic polymer A]
[Manufacturing Example A-1]
70.0 parts by mass of ethyl acetate [organic solvent] was charged into a reaction vessel equipped with a thermometer, a stirrer, a nitrogen introduction tube, a reflux condenser, and a sequential dropping device.
In another container, 50.0 parts by mass of n-butyl acrylate [n-BA; acrylic acid alkyl ester monomer] and 46.3 parts by mass of 2-ethylhexyl acrylate [2EHA; acrylic acid alkyl ester monomer]. , 4-Hydroxybutyl acrylate [4HBA; monomer having a hydroxyl group] 3.0 parts by mass, and acrylic acid [AA; monomer having a carboxy group] 0.7 parts by mass, and mix them to form a monomer. It was made into a mixture.
Of this monomer mixture, 25.0% by mass was added into the reaction vessel. Then, after replacing the air in the reaction vessel with nitrogen gas, 0.01 part by mass of 2,2'-azobisisobutyronitrile [AIBN; polymerization initiator] was added, and the mixture was stirred in a nitrogen atmosphere. The temperature of the contents in the reaction vessel was raised to 85 ° C. to start the initial reaction.
In the reaction vessel after the initial reaction was almost completed, 75.0% by mass of the remaining monomer mixture and a mixture of 20.0 parts by mass of ethyl acetate and 0.02 parts by mass of AIBN were added over about 2 hours. The contents in the reaction vessel were reacted while being added sequentially, and after the addition was completed, the reaction was further carried out for 2 hours to obtain a reaction product (a1).
Then, a solution prepared by dissolving 0.25 parts by mass of t-butylperoxypivalate (polymerization initiator) in 25.0 parts by mass of ethyl acetate in the reaction product (a1) in the reaction vessel was added dropwise over 1 hour. Then, after the completion of the dropping, the reaction was further carried out for 1.5 hours to obtain a reaction product (a2). The obtained reaction product (a2) was diluted with ethyl acetate to obtain a solution of the (meth) acrylic polymer A-1 having a solid content concentration of 45% by mass.

The "solid content concentration" here means the mass ratio of the (meth) acrylic polymer A-1 in the solution of the (meth) acrylic polymer A-1.
The same applies to each of the following (meth) acrylic polymers A-2 to A-7 solutions.

[Manufacturing Examples A-2 and A-4 to A-7]
In Production Examples A-2 and A-4 to A-7, the monomer composition of the (meth) acrylic polymer A was changed to the monomer composition shown in Table 1, and the amount of the organic solvent used. And, except that the weight average molecular weight (Mw) of the (meth) acrylic polymer A was adjusted to the weight average molecular weight (Mw) shown in Table 1 by adjusting at least one of the amounts of the polymerization initiator used. The same operation as in Production Example A-1 was carried out to obtain solutions of (meth) acrylic polymers A-2 and A-4 to A-7 having a solid content concentration of 45% by mass.

[Manufacturing Example A-3]
In Production Example A-3, by adjusting at least one of the amount of the organic solvent used and the amount of the polymerization initiator used, the weight average molecular weight (Mw) of the (meth) acrylic polymer A is determined by the weight shown in Table 1. The same operation as in Production Example A-1 was carried out except that the average molecular weight (Mw) was adjusted, to obtain a solution of the (meth) acrylic polymer A-3 having a solid content concentration of 45% by mass.

Monomer composition (unit: mass%), hydroxyl value (unit: mgKOH / g), acid value (unit: mgKOH / g), weight average molecular weight of (meth) acrylic polymers A-1 to A-7 [ Mw, ten thousand (in the table, indicated as "× 10 ^4)], and the glass transition temperature (Tg, unit: ° C.) shown in Table 1.

The weight average molecular weight (Mw) of the (meth) acrylic polymers A-1 to A-7 is the same as the method for measuring the weight average molecular weight (Mw) of the specific (meth) acrylic polymer (A) described above. Measured by method.
The glass transition temperature (Tg) of the (meth) acrylic polymers A-1 to A-7 is the same as the method for calculating the glass transition temperature (Tg) of the specific (meth) acrylic polymer (A) described above. Calculated by method.

The hydroxyl value and acid value of the (meth) acrylic polymers A-1 to A-7 are the same as the method for calculating the hydroxyl value and acid value of the specific (meth) acrylic polymer (A) described above, respectively. Calculated by

For example, the hydroxyl value of the (meth) acrylic polymer A-1 was calculated as follows. The content of 4HBA (A1) in the (meth) acrylic polymer A-1 is 3.0% by mass, and the molecular weight of 4HBA (A2) is 144.17. The number of hydroxyl groups (A3) contained in one molecule of 4HBA is 1.
Hydroxy group value (mgKOH / g) of (meth) acrylic polymer A-1 = {(A1 / 100) ÷ A2} × 56.1 × 1000 × A3 = {(3.0/100) ÷ 144.17} × 56.1 × 1000 × 1 = 11.67 ・ ・ ・ ≈11.7

The acid value of the (meth) acrylic polymer A-1 was calculated as follows. The content of AA (a1) in the (meth) acrylic polymer A-1 is 0.7% by mass, and the molecular weight of AA (a2) is 72.06. The number of carboxy groups (a3) contained in one molecule of AA is 1.
Acid value of (meth) acrylic polymer A-1 (mgKOH / g) = {(a1 / 100) ÷ a2} × 56.1 × 1000 × a3 = {(0.7 / 100) ÷ 72.06} × 56.1 × 1000 × 1 = 5.44 ・ ・ ・ ≈5.4

Among the (meth) acrylic polymers A-1 to A-7 obtained above, the (meth) acrylic polymers A-1 to A-5 and A-7 are specified (meth) in the present invention. ) Corresponds to the acrylic polymer (A).

Details of each monomer shown in Table 1 are as shown below.
"N-BA": n-butyl acrylate (acrylic acid alkyl ester monomer)
"2EHA": 2-ethylhexyl acrylate (acrylic acid alkyl ester monomer)
"4HBA": 4-Hydroxybutyl acrylate (monomer having a hydroxyl group)
"AA": Acrylic acid (monomer having a carboxy group)
"PPGMA": Polypropylene glycol monomethacrylate [Product name: Blemmer (registered trademark) PP-800, NOF CORPORATION] (monomer having a hydroxyl group and a propylene oxide chain)

In Table 1, "-" described in the column of monomer composition means that the monomer corresponding to the column is not contained.
In Table 1, "weight average molecular weight" is expressed as "Mw", and "glass transition temperature" is expressed as "Tg".

[Preparation of adhesive composition]
[Example 1]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, 7.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), was added to the flask, and the mixture was sufficiently stirred to obtain Example 1. The pressure-sensitive adhesive composition of the above was obtained.

[Examples 2, 3, and 5]
In Examples 2, 3, and 5, the same operations as in Example 1 were performed except that the type of the specific (meth) acrylic polymer (A) was changed to the types shown in Table 2, and the same operations as in Example 1 were performed. Each of the pressure-sensitive adhesive compositions of 3 and 5 was obtained.

[Example 4]
222.2 mass of a solution of the (meth) acrylic polymer A-4, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc. 7.0 parts by mass, which is a specific isocyanate-based cross-linking agent (B), and dioctyl tin dilaurate (DOTDL), which is a cross-linking catalyst, 0. 02 parts by mass was added and sufficiently stirred to obtain the pressure-sensitive adhesive composition of Example 4.

[Examples 6 and 7]
In Examples 6 and 7, the same operations as in Example 1 were performed except that the blending amount of the specific isocyanate-based cross-linking agent (B) was changed to the blending amount shown in Table 2, and the adhesives of Examples 6 and 7 were obtained. An agent composition was obtained.

[Example 8]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, 7.0 parts by mass of Takenate (registered trademark) M605NE [trade name, Mitsui Chemicals, Inc.] solid content, which is a specific isocyanate-based cross-linking agent (B), was added to the flask, and the mixture was sufficiently stirred. The pressure-sensitive adhesive composition of Example 8 was obtained.

[Example 9]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, 7.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Kagaku Co., Ltd.], which is a specific isocyanate-based cross-linking agent (B), is different from the specific isocyanate-based cross-linking agent (B). 9.0 parts by mass (3.0 parts by mass as solid content) of a diluted solution of Sumijour (registered trademark) N3300 [trade name, Sumika Cobestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent, was added. The pressure-sensitive adhesive composition of Example 9 was obtained with sufficient stirring.

[Example 10]
In Example 10, except that DOWNSIL (registered trademark) SH-3737M [trade name, compound represented by formula (A), Dow Toray Co., Ltd.], which is a polyether-modified silicone compound, was not blended. The same operation as in Example 1 was carried out to obtain the pressure-sensitive adhesive composition of Example 10.

[Example 11]
In Example 11, the blending amount of DOWNSIL (registered trademark) SH-3773M [trade name, compound represented by the formula (A), Dow Toray Co., Ltd.], which is a polyether-modified silicone compound, was set to "0.3 mass". The same operation as in Example 1 was carried out except that "parts" was changed to "0.6 parts by mass" to obtain the pressure-sensitive adhesive composition of Example 11.

[Example 12]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 _{25 parts by mass and 0.25 parts by mass of LiTFS [LiCF 3} SO ₃ (lithium trifluoromethanesulfonate), Morita Chemical Industry Co., Ltd.], which is an antistatic agent, were charged, and the liquid temperature of the contents in the flask was set to 25. The mixture was stirred for 4 hours while keeping the temperature around ° C.
Next, 7.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), was added to the flask, and the mixture was sufficiently stirred to form Example 12. The pressure-sensitive adhesive composition of the above was obtained.

[Example 13]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, 7.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Kagaku Co., Ltd.], which is a specific isocyanate-based cross-linking agent (B), and aluminum chelate A, which is a metal chelate-based cross-linking agent [ Product name, Kawaken Fine Chemicals Co., Ltd.] 0.1 parts by mass was added and sufficiently stirred to obtain the pressure-sensitive adhesive composition of Example 13.

[Example 14]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, 7.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), and dioctyl tin dilaurate (DOTDL) 0, which is a cross-linking catalyst. .02 parts by mass was added and thoroughly stirred to obtain the pressure-sensitive adhesive composition of Example 14.

[Comparative Example 1]
In Comparative Example 1, instead of blending 100 parts by mass of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), the (meth) acrylic polymer A as the comparative polymer The same operation as in Example 1 was carried out except that 100 parts by mass of -6 was blended to obtain a pressure-sensitive adhesive composition of Comparative Example 1.

[Comparative Example 2]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, 3.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), was added to the flask, and the mixture was sufficiently stirred to make Comparative Example 2. The pressure-sensitive adhesive composition of the above was obtained.

[Comparative Example 3]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, 17.0 parts by mass of Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), was added to the flask, and the mixture was sufficiently stirred. A pressure-sensitive adhesive composition was obtained.

[Comparative Example 4]
In Comparative Example 4, the same operation as in Example 1 was performed except that Takenate (registered trademark) M631N [trade name, Mitsui Chemicals, Inc.], which is a specific isocyanate-based cross-linking agent (B), was not blended. The pressure-sensitive adhesive composition of Comparative Example 4 was obtained.

[Comparative Example 5]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, as a comparative cross-linking agent, a dilution of Sumijour (registered trademark) N3300 [trade name, Sumika Cobestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B). 21.0 parts by mass of a product (7.0 parts by mass as a solid content) was added, and the mixture was sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 5.

[Comparative Example 6]
222.2 mass of a solution of the (meth) acrylic polymer A-7, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Co., Ltd.] 0.3 A part by mass was charged, and the mixture was stirred for 4 hours while maintaining the liquid temperature of the contents in the flask at around 25 ° C.
Next, in the flask, as a comparative cross-linking agent, a dilution of Sumijour (registered trademark) N3300 [trade name, Sumika Cobestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B). 21.0 parts by mass of a product (7.0 parts by mass as a solid content) was added, and the mixture was sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 6.

[Comparative Example 7]
222.2 mass of a solution of the (meth) acrylic polymer A-1, which is the specific (meth) acrylic polymer (A), in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. Parts (100 parts by mass as solid content) and DOWNSIL® (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Toray Dow Corning Co., Ltd.] 0. 3 parts by mass and 7.0 parts by mass of polypropylene glycol [trade name: polypropylene glycol, diol type, 2000, Fujifilm Wako Pure Chemical Industries, Ltd.] were charged, and the liquid temperature of the contents in the flask was around 25 ° C. It was stirred for 4 hours while holding it in.
Next, in the flask, as a comparative cross-linking agent, a dilution of Sumijur (registered trademark) N3300 [trade name, Sumika Cobestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B). 21.0 parts by mass of a product (7.0 parts by mass as a solid content) was added, and the mixture was sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 7.

In Tables 2 and 3, "-" means that the corresponding component is not contained.
The blending amounts in Tables 2 and 3 are all solid content conversion values.

Details of each of the cross-linking agents shown in Tables 2 and 3 are as shown below.
<Specific isocyanate-based cross-linking agent (B)>
"M631N" [Product name: Takenate (registered trademark) M631N, an adduct compound of an isocyanate compound containing a structure derived from hexamethylene diisocyanate (HMDI) and a propylene oxide structure, a trifunctional isocyanate compound, Mitsui Chemicals, Inc.]
"M605NE" [Product name: Takenate (registered trademark) M605NE, an adduct of an isocyanate compound containing a structure derived from isocyanatomethylcyclohexane and a propylene oxide structure, a trifunctional isocyanate compound, Mitsui Chemicals, Inc.]

<Other cross-linking agents or comparative cross-linking agents>
"N3300" [Product name: Sumijour (registered trademark) N3300, hexamethylene diisocyanate (HMDI) trimester, Sumika Cobestrourethane Co., Ltd.]: Isocyanate-based cross-linking agent "Aluminum chelate A" [Product name, aluminum Trisacetylacetonate, Kawaken Fine Chemicals Co., Ltd.]: Metal chelate-based cross-linking agent

[evaluation]
The following evaluation was performed using the pressure-sensitive adhesive composition prepared above.
The results are shown in Table 4.

1. 1. Peeling force <Preparation of protective film for peeling force evaluation>
Amount of application after drying on a polyethylene terephthalate (PET) film as a base material [trade name: Teijin (registered trademark) Tetron (registered trademark) film, model number: G2, thickness: 38 μm, Teijin Film Solution Co., Ltd.] The pressure-sensitive adhesive composition was applied so that the pressure was 15 g / m ^{2, and a coating film was 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 substrate.
Next, a release film in which the exposed surface of the adhesive film formed on the substrate was surface-treated with a silicone-based release treatment agent [trade name: Film Vina (registered trademark) 100E-0010N023, thickness: 100 μm, Fujimori Kogyo ( Co., Ltd.], and then passed through a pressure nip roll to press and bond the adhesive film and the release film. Next, the pressure-sensitive adhesive film was cured for 96 hours in an environment with an ambient temperature of 23 ° C. and 50% RH to obtain a protective film for evaluating peeling force having a laminated structure of a base material / pressure-sensitive adhesive layer / peeling film.

<Evaluation test>
(1) Low-speed peeling force The peeling force evaluation protective film produced above was cut into a size of 25 mm × 150 mm, and a peeling force evaluation protective film piece was prepared.
Next, the release film was peeled off from the prepared protective film piece for evaluation of peeling force, and the surface of the pressure-sensitive adhesive layer exposed by the peeling was a polyethylene terephthalate (PET) film as an adherend [trade name: Cosmoshine (registered trademark)). A4300, thickness: 300 μm, Toyobo Co., Ltd.] was overlaid on the surface and then crimped using a tabletop laminating machine to prepare a test sample.
This test sample was left for 24 hours in an environment with an atmospheric temperature of 23 ° C. and 50% RH. Next, a single column type material testing machine [model number: STA-1225, A & D Co., Ltd.] was used as a measuring device, and the peeling speed was 0.3 m / min in an environment of an atmospheric temperature of 23 ° C. and 50% RH. Measure the peeling force (unit: N / 25 mm) when the protective film piece for evaluation of peeling force (composition: adhesive layer / base material) is peeled 180 ° in the long side (150 mm) direction from the PET film under the above conditions. bottom. Then, the low-speed peeling force was evaluated according to the following evaluation criteria.
If the evaluation result is "AA", "A", or "B", it is determined that the pressure-sensitive adhesive layer exhibits an appropriate low-speed peeling force.

-Evaluation criteria-
AA: The peeling force is 0.15 N / 25 mm or more.
A: The peeling force is 0.10 N / 25 mm or more and less than 0.15 N / 25 mm.
B: The peeling force is 0.07 N / 25 mm or more and less than 0.10 N / 25 mm.
C: The peeling force is less than 0.07 N / 25 mm.

(2) High-speed peeling force A test sample was obtained by the same procedure as in "(1) Low-speed peeling force" above.
This test sample was left for 24 hours in an environment with an atmospheric temperature of 23 ° C. and 50% RH. Next, a peeling tester [model number: horizontal TE-720, Tester Sangyo Co., Ltd.] was used as a measuring device, and the PET film was used under the conditions of an atmospheric temperature of 23 ° C. and a peeling speed of 30 m / min under the condition of an atmospheric temperature of 23 ° C. and 50% RH. The peeling force (unit: N / 25 mm) when the protective film piece for evaluation of peeling force (composition: pressure-sensitive adhesive layer / base material) was peeled 180 ° in the long side (150 mm) direction was measured. Then, the high-speed peeling force was evaluated according to the following evaluation criteria.
If the evaluation result is "AA", "A", or "B", it is determined that the pressure-sensitive adhesive layer exhibits an appropriate high-speed peeling force.

-Evaluation criteria-
AA: The peeling force is less than 0.70 N / 25 mm.
A: The peeling force is 0.70 N / 25 mm or more and less than 0.80 N / 25 mm.
B: The peeling force is 0.80 N / 25 mm or more and less than 1.00 N / 25 mm.
C: The peeling force is 1.00 N / 25 mm or more.

(3) Balance between low-speed peeling force and high-speed peeling force The value of the low-speed peeling force measured in the above "(1) Low-speed peeling force" and the value of the low-speed peeling force measured in the above "(2) High-speed peeling force" were measured. Based on the value of the high-speed peeling force, the balance between the low-speed peeling force and the high-speed peeling force was evaluated.
Specifically, the balance between the low-speed peeling force and the high-speed peeling force is evaluated according to the following evaluation criteria based on the value obtained by dividing the low-speed peeling force value by the high-speed peeling force value and rounding off the third digit after the decimal point. bottom.
If the evaluation result is "AA", "A", or "B", it is determined that the pressure-sensitive adhesive layer has a good balance between the low-speed peeling force and the high-speed peeling force.

-Evaluation criteria-
AA: "Low speed peeling force / high speed peeling force" is 0.20 or more.
A: "Low speed peeling force / high speed peeling force" is 0.15 or more and less than 0.20.
B: "Low speed peeling force / high speed peeling force" is 0.10 or more and less than 0.15.
C: "Low speed peeling force / high speed peeling force" is less than 0.10.

As shown in Table 4, a (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group [that is, a specific (meth) acrylic polymer (A)] and an isocyanate type having an alkylene oxide chain It contains a cross-linking agent (B) [that is, a specific isocyanate-based cross-linking agent (B)], and the content of the specific isocyanate-based cross-linking agent (B) is 100 parts by mass of the specific (meth) acrylic polymer (A). On the other hand, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive compositions of Examples 1 to 14, which is in the range of 5 parts by mass or more and 15 parts by mass or less, has a good balance between low-speed peeling force and high-speed peeling force. Was confirmed.

On the other hand, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 1 in which the (meth) acrylic polymer A has neither a hydroxyl group nor a carboxy group can be evaluated without peeling from the adherend. could not.
Comparative Example in which the specific isocyanate-based cross-linking agent (B) is contained, but the content of the specific isocyanate-based cross-linking agent (B) is less than 5 parts by mass with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of No. 2 had an excessively high high-speed peeling force, and the balance between the low-speed peeling force and the high-speed peeling force was not good.
Comparative Example 3 in which the specific isocyanate-based cross-linking agent (B) is contained, but the content of the specific isocyanate-based cross-linking agent (B) exceeds 15 parts by mass with respect to 100 parts by mass of the specific (meth) acrylic polymer (A). It was confirmed that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of No. 1 had an excessively low low-speed peeling force, and the balance between the low-speed peeling force and the high-speed peeling force was not good.
The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 4 containing no specific isocyanate-based cross-linking agent (B) did not peel off from the adherend and could not be evaluated.

The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 5 containing an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B) instead of the specific isocyanate-based cross-linking agent (B) has a low-speed peeling force. It was confirmed that it was excessively low and the balance between the low-speed peeling force and the high-speed peeling force was not good.
Instead of the specific isocyanate-based cross-linking agent (B), an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B) is contained, and the (meth) acrylic polymer A is added to the hydroxyl group and the carboxy group. The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Comparative Example 6, which is a specific (meth) acrylic polymer (A) having a propylene oxide chain which is an alkylene oxide chain, has an excessively low low-speed peeling force and low-speed peeling. It was confirmed that the balance between the force and the high-speed peeling force was not good.
A pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition of Comparative Example 7 containing an isocyanate-based cross-linking agent different from the specific isocyanate-based cross-linking agent (B) instead of the specific isocyanate-based cross-linking agent (B) and containing polypropylene glycol. It was confirmed that the layer had an excessively high high-speed peeling force, and the balance between the low-speed peeling force and the high-speed peeling force was not good.

Claims (6)

A (meth) acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group, and
Containing an isocyanate-based cross-linking agent (B) having an alkylene oxide chain,
Adhesive for optical member protective film in which the content of the isocyanate-based cross-linking agent (B) is in the range of 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (A). Composition. The pressure-sensitive adhesive composition for an optical member protective film according to claim 1, wherein the alkylene oxide chain contained in the isocyanate-based cross-linking agent (B) contains a propylene oxide structure. The pressure-sensitive adhesive composition for an optical member protective film according to claim 1 or 2, wherein the isocyanate-based cross-linking agent (B) is a trifunctional isocyanate compound. The pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 3, which contains an antistatic agent. The pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 4, which comprises a polyether-modified silicone compound. Optics including a base material and a pressure-sensitive adhesive layer provided on the base material and formed by the pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 5. Member protection film.