JP7337015B2 - PSA COMPOSITION FOR OPTICAL MEMBER PROTECTIVE FILM AND OPTICAL MEMBER PROTECTIVE FILM - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition for an optical member protective film and an optical member protective film.

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

For example, in Patent Document 1, 100 parts by mass of a polymer (A) having a glass transition temperature of less than 0°C and a (meth) acrylic having a weight average molecular weight of 1000 or more and less than 50000 and a glass transition temperature of 30 to 300°C A pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition containing 0.05 to 3 parts by mass of a polymer (B) and an organopolysiloxane compound (C) having a specific polyoxyalkylene chain is coated on at least one side of a support. is disclosed.

JP 2013-216769 A

The pressure-sensitive adhesive composition used for the protective film used for the optical member (hereinafter also referred to as "the pressure-sensitive adhesive composition for the optical member protective film") has protective properties after the protective film is attached to the surface of the optical member. It is required to form a pressure-sensitive adhesive layer that is difficult to cause problems such as peeling and displacement from the optical member for the time required, and that can be efficiently peeled from the optical member at the stage when protection is no longer required.
Here, the pressure-sensitive adhesive layer that is less likely to cause problems such as peeling and displacement from the optical member is the adhesive strength (so-called , low speed peel strength). The adhesive layer that can be efficiently peeled from the optical member can be evaluated by the adhesive strength (so-called high-speed peel strength) measured when the protective film is peeled from the optical member at high speed (30 m/min).

However, when trying to control the low-speed peeling force and high-speed peeling force of the pressure-sensitive adhesive layer of the protective film, both exhibit similar 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, due to the emergence of flexible displays, opportunities to attach protective films to curved surfaces are increasing. When the protective film is attached to a curved surface, problems such as peeling off from the optical member and displacement are more likely to occur than when the protective film is attached to a flat surface. For this reason, there is a tendency that the pressure-sensitive adhesive layer included in the protective film is required to have a higher low-speed peeling force than in the past. On the other hand, the peeling speed of the protective film from the optical member tends to increase 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, if the protective film is peeled from the optical member at a higher speed, the optical member tends to be damaged. For this reason, there is a tendency that the pressure-sensitive adhesive layer included in the protective film is required to have a lower high-speed peeling force than in the past.
Therefore, it is more difficult to adjust the balance between the low-speed peel force and the high-speed peel force, and an optical member that can form a pressure-sensitive adhesive layer with a good balance between the low-speed peel force and the high-speed peel force. It was difficult to realize a pressure-sensitive adhesive composition for protective films.

The problem to be solved by the present invention is to provide a pressure-sensitive adhesive composition for an optical member protective film and an optical member protective film that can form a pressure-sensitive adhesive layer having a good balance between low-speed peel strength and high-speed peel strength. .

Specific means for solving the problems include the following aspects.
<1> a (meth)acrylic polymer (A) having at least one of a hydroxyl group and a carboxyl group;
a carboxy-modified silicone compound (B);
and an isocyanate-based cross-linking agent (C),
For an optical member protective film, wherein the content of the carboxy-modified silicone compound (B) is in the range of 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer (A) Adhesive composition.
<2> The pressure-sensitive adhesive composition for an optical member protective film according to <1>, which contains a polyether-modified silicone compound.
<3> The adhesive composition for an optical member protective film according to <1> or <2>, wherein the carboxy-modified silicone compound (B) has a viscosity of 100 mm ² /s or more.
<4> The adhesive composition for an optical member protective film according to any one of <1> to <3>, wherein the carboxy-modified silicone compound (B) has a functional group equivalent weight of 300 g/mol or more.
<5> The pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <4>, wherein the isocyanate-based cross-linking agent (C) is hexamethylene diisocyanate.
<6> a substrate; a pressure-sensitive adhesive layer provided on the substrate and formed from the pressure-sensitive adhesive composition for an optical member protective film according to any one of <1> to <5>; An optical member protective film.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition for optical member protective films and an optical member protective film which can form the adhesive layer with the favorable balance of low-speed peeling force and high-speed peeling force are provided.

Specific embodiments of the present invention will be described in detail below. However, the present invention is by no means limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

In this specification, the numerical range indicated using "to" means a range including the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of the numerical range described in other steps. . Moreover, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
In the present specification, a combination of two or more preferred aspects is a more preferred aspect.
In the present specification, the amount of each component means the total amount of the multiple types of substances unless otherwise specified when there are multiple types of substances corresponding to each component.

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 units [i.e., (meth)acrylic polymer total structural units] is 50% by mass or more.
As used herein, "(meth)acrylic monomer" means a monomer having a (meth)acryloyl group.

As used herein, "(meth)acrylic" is a term that includes both "acrylic" and "methacrylic", and "(meth)acrylate" is a term that includes both "acrylate" and "methacrylate". , "(meth)acryloyl" is a term encompassing both "acryloyl" and "methacryloyl".

As used herein, "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 substance before the completion of the cross-linking reaction.
As used herein, the "adhesive layer" means a film made of a substance after the crosslinking reaction in the adhesive composition is completed.

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

As used herein, the term "low-speed peeling force" means that the protective film attached to the adherend is peeled off from the adherend at a low speed (that is, 0.3 m/min) in the longitudinal direction of the protective film at 180°. means the adhesive strength measured in In addition, the detailed measuring method is as shown in the examples below.
As used herein, the term "appropriate low-speed peel strength" means an adhesive strength that is strong enough to prevent problems such as peeling from adherends and slippage.

As used herein, the term "high-speed peeling force" refers to the protective film attached to the adherend, measured when the protective film is peeled from the adherend at a high speed (i.e., 30 m/min) in the longitudinal direction of the protective film at 180°. means the adhesive strength to be applied. In addition, the detailed measuring method is as shown in the later-described Examples.
As used herein, "appropriate high-speed peel strength" means adhesive strength strong enough to allow efficient peeling from adherends.

In the present specification, the term "a pressure-sensitive adhesive layer having a good balance between low-speed peeling force and high-speed peeling force" means that problems such as peeling and displacement from the adherend are unlikely to occur, and the adhesive layer can be efficiently peeled from the adherend. It means a pressure-sensitive adhesive layer having as strong an adhesive force 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") comprises a (meth)acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group [hereinafter referred to as It is also called "specific (meth)acrylic polymer (A)". ], a carboxy-modified silicone compound (B), and an isocyanate-based cross-linking agent (C), wherein the content of the carboxy-modified silicone compound (B) is 100 masses of the (meth)acrylic polymer (A) It is in the range of 0.05 parts by mass or more and 5 parts by mass or less.
According to the pressure-sensitive adhesive composition of the present invention, a pressure-sensitive adhesive layer having a good balance between low-speed peel strength and high-speed peel strength can be formed.
Although the reason why the pressure-sensitive adhesive composition of the present invention can exhibit such effects is not clear, the present inventors presume as follows. However, the following assumptions are not intended to restrictively interpret the pressure-sensitive adhesive composition of the present invention, but are explained as an example.

The pressure-sensitive adhesive composition of the present invention contains the carboxy-modified silicone compound (B) in a specific range of amount relative to the specific (meth)acrylic polymer (A). Since the carboxy-modified silicone compound (B) has a siloxane structure, it has a low surface free energy. Therefore, the carboxy-modified silicone compound (B) is added near the surface ( It is thought to be moderately localized near the so-called interface with the adherend). The carboxy-modified silicone compound (B) has a carboxy group, and the carboxy group in the carboxy-modified silicone compound (B) reacts with the isocyanate group in the isocyanate cross-linking agent (C) to form an amide bond. In addition, since the carboxy-modified silicone compound (B) has a higher degree of freedom in the film than the specific (meth)acrylic polymer (A), the carboxy groups in the carboxy-modified silicone compound (B) It is thought that the isocyanate groups in the isocyanate-based cross-linking agent (C) preferentially react with at least one of hydroxyl groups and carboxy groups in the specific (meth)acrylic polymer (A). That is, when a pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition of the present invention, an amide bond is formed near the interface between the pressure-sensitive adhesive layer and the adherend. Since the cohesive force of the adhesive layer formed by amide bonds is relatively high, relatively hard portions are considered to be moderately localized in the vicinity of the interface between the adhesive layer and the adherend. If relatively hard portions are moderately localized near the interface between the adhesive layer and the adherend, the adhesive layer will not excessively wet the adherend, and the adhesive layer will have an appropriate high-speed peeling force. It is considered to indicate
From the above, it is presumed that the pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer having a good balance between low-speed peel strength and high-speed peel strength.

In contrast to the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive composition described in Patent Document 1 reduces the high-speed peeling force of the pressure-sensitive adhesive layer by an organopolysiloxane compound having a polyoxyalkylene chain. For this reason, in the adhesive layer formed from the adhesive composition described in Patent Document 1, not only the high-speed peel strength but also the low-speed peel strength is considered to be reduced. It is presumed that it does not meet the standard set.

[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 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 hydroxyl groups among hydroxyl groups and carboxy groups, or may be a polymer having only carboxy groups. 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. At least one of a hydroxyl group and a carboxy group may be introduced by substitution into a homopolymer of a (meth) acrylic monomer that does not have a (meth) acrylic monomer having at least one of a hydroxyl group and a carboxy group. may be a copolymer of 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 monomer, 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 structural unit derived from a monomer having a hydroxyl group and a monomer having a carboxy group, which will be described later. It is an embodiment having at least one of a hydroxyl group and a carboxy group by including at least one of structural units derived from the body.

<Structural Unit Derived from Monomer Having Hydroxyl Group>
The specific (meth)acrylic polymer (A) preferably contains structural units derived from a monomer having a hydroxyl group.
As used herein, the term “structural unit derived from a monomer having a hydroxyl group” means a structural unit formed by addition polymerization of a monomer having a hydroxyl group.

The type of hydroxyl group-containing monomer is not particularly limited.
Specific examples of monomers having a hydroxyl group include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl -3-hydroxybutyl (meth)acrylate, 1,3-dimethyl-3-hydroxybutyl (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth)acrylate, 2-ethyl-3-hydroxyhexyl (Meth) 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 etc.
The monomer having a hydroxyl group is preferably a hydroxyalkyl (meth)acrylate, more preferably a hydroxyalkyl (meth)acrylate having a hydroxyalkyl group having 1 to 5 carbon atoms, and a hydroxyalkyl group having 2 to 4 carbon atoms. is more preferred, and 4-hydroxybutyl acrylate is particularly preferred.

When the specific (meth)acrylic polymer (A) contains a structural unit derived from a monomer having a hydroxyl group, it may contain only one type of structural unit derived from a 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, a structural unit derived from the monomer having a hydroxyl group in the specific (meth)acrylic polymer (A) Although the content of is not particularly limited, for example, it is preferably in the range of 0.1% by mass or more and 10% by mass or less with respect to all structural units of the specific (meth)acrylic polymer (A), and 0 It is more preferably in the range of 5% by mass or more and 8% by mass or less, and even more preferably in the range of 1% by mass or more and 5% by mass or less.
The content of structural units derived from a monomer having a hydroxyl group in the specific (meth)acrylic polymer (A) is 0.1 mass with respect to all 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 structural units derived from a monomer having a hydroxyl group in the specific (meth)acrylic polymer (A) is 10% by mass or less with respect to all structural units of the specific (meth)acrylic polymer (A). Then, there is a tendency that a pressure-sensitive adhesive layer having a better balance between low-speed peel strength and high-speed peel strength can be formed.

<Structural Unit Derived from Monomer Having Carboxy Group>
The specific (meth)acrylic polymer (A) preferably contains structural units derived from a monomer having a carboxy group.
As used herein, the term "structural 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 monomers having a carboxy group include acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, ω-carboxy-polycaprolactone mono(meth)acrylate [ Examples thereof include ω-carboxy-polycaprolactone (n≈2) monoacrylate], succinic acid esters [eg, 2-acryloyloxyethyl-succinic acid], and the like.
Acrylic acid is preferred 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 type of structural unit derived from a monomer having a carboxy group. , may contain two or more kinds.

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

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

In the present specification, "a structural unit derived from a (meth)acrylic acid alkyl ester monomer" means a structural unit formed by addition polymerization of a (meth)acrylic acid alkyl ester monomer.
In addition, 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 (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.
The number of carbon atoms in the alkyl group is, for example, preferably in the range of 1 to 18, more preferably in the range of 1 to 12, and more preferably in the range of 1 to 8, from the viewpoint of adhesive strength. More preferred.
In particular, when the number of carbon atoms in the alkyl group is in the range of 1 to 8, the pressure-sensitive adhesive layer to be formed tends to moderately wet and spread on the adherend, exhibiting more appropriate low-speed peel strength.

Specific examples of (meth) acrylic acid alkyl ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, s-butyl (meth) acrylates, t-butyl (meth)acrylate, n-octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, i-nonyl (meth)acrylate, n-decyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate and the like.
At least one selected from n-butyl acrylate and 2-ethylhexyl acrylate is preferable as the (meth)acrylic acid alkyl ester monomer.

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

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

<Other structural units>
The specific (meth)acrylic polymer (A) can contain structural units other than the above-described structural units (so-called other structural units) as long as the effects of the present invention are exhibited.

Examples of monomers constituting other structural units include (meth)acrylates having an aromatic ring represented by benzyl (meth)acrylate and phenoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate and ethoxyethyl Alkoxyalkyl (meth)acrylates typified by (meth)acrylates, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and aromatic monovinyls typified by vinyltoluene, acrylonitrile and methacrylates. vinyl cyanides typified by lonitrile; and vinyl esters typified by vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate. Various derivatives of these monomers are also included.

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 thereof.

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, depending 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 for example, it is preferably −40° C. or less, and −50° C. or less. It is more preferably −60° 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 low-speed peel strength and high-speed peel strength can be formed.
Although the lower limit of the glass transition temperature of the specific (meth)acrylic polymer (A) is not particularly limited, it is preferably −70° C. or higher, for example.

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

In formula 1, Tg1, Tg2, ..., Tg (k-1), and Tgk are absolute when each monomer constituting the specific (meth) acrylic polymer (A) is a homopolymer Each represents the glass transition temperature expressed in temperature. m1, m2, . (k−1)+mk=1.
The absolute temperature can be converted to a Celsius temperature by subtracting 273 from the absolute temperature, and the Celsius temperature can be converted to an absolute temperature by adding 273 to the Celsius temperature.

In the present specification, the "glass transition temperature represented by the absolute temperature of a homopolymer" refers to the absolute temperature of the homopolymer produced by polymerizing the monomer alone. means temperature.
The glass transition temperature of the homopolymer was measured using a differential scanning calorimeter (DSC) [model number: EXSTAR6000, Seiko Instruments Inc.] in a nitrogen stream, with a measurement sample of 10 mg and a heating rate of 10° C./min. The inflection point of the measured DSC curve is taken as the glass transition temperature of the homopolymer.

The "glass transition temperature represented by the Celsius temperature when converted to a homopolymer" of representative monomers is -76 ° C. for 2-ethylhexyl acrylate (2EHA) and -10 ° C. for 2-ethylhexyl methacrylate (2EHMA). , n-butyl acrylate (n-BA) is −57° C., n-butyl methacrylate (n-BMA) is 21° C., t-butyl acrylate (t-BA) is 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, isobornyl methacrylate (IBXMA) is 155°C, isobornyl 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) is 55 ° C., 2-hydroxypropyl acrylate (2HPA) is -7 ° C., acrylic acid (AA) is 163 ° C., i-octyl acrylate (i-OA) is -75 ° C., dimethylaminoethyl methacrylate ( DM) is 18° C., ω-carboxy-polycaprolactone (n≈2) monoacrylate is −30° C., and 2-acryloyloxyethyl-succinic acid is −40° C.

The glass transition temperature of the specific (meth)acrylic polymer (A) can be appropriately adjusted, for example, by using two or more monomers having different glass transition temperatures when converted into homopolymers.

<<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 to 2,000,000, and more than 200,000 to 1,500,000. It is more preferably in the range, more preferably in the range of over 200,000 to 1,000,000 or less, and particularly preferably in the range of over 200,000 to 800,000 or less.
When the weight average molecular weight of the specific (meth)acrylic polymer (A) is within the above range, the wettability to the adherend is moderate, and the extreme decrease in low-speed peel force and the extreme increase in high-speed peel force are further suppressed. be done. Therefore, there is a tendency that a pressure-sensitive adhesive layer having a better balance between low-speed peel strength and high-speed peel strength can be formed.

The weight average molecular weight of the specific (meth)acrylic polymer (A) is a value measured by the following method. Specifically, it is measured according to the following (1) to (3).
(1) A solution of the specific (meth)acrylic polymer (A) is applied to release paper and dried at 100° C. for 1 minute to obtain a film-like specific (meth)acrylic polymer (A).
(2) Using the film-shaped specific (meth)acrylic polymer (A) obtained in (1) above and tetrahydrofuran, a sample solution having a solid content concentration of 0.2% by mass is obtained. The term "solid content concentration" as used herein means the mass ratio of the specific (meth)acrylic polymer (A) in 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 into HLC-8220, Tosoh Corporation]
Column: Four TSK-GEL GMHXL [Tosoh Corporation] connected in series Column temperature: 40 ° C.
Eluent: Tetrahydrofuran Injection volume of sample solution: 100 μL
Flow rate: 0.8 mL/min

The weight average molecular weight of the specific (meth)acrylic polymer (A) can be adjusted to the desired value 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 valued.

<<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. is preferably in the range of 0.5 mgKOH/g or more and 30 mgKOH/g or less, more preferably 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, there is a tendency that a pressure-sensitive adhesive layer having a better balance between low-speed peel strength and high-speed peel strength can be formed.

The hydroxyl value of the specific (meth)acrylic polymer (A) is a value determined by the following formula. In addition, in the following formulas, 56.1 is the molecular weight of KOH.
Hydroxyl value (mgKOH/g)
= {(A1/100)/A2} x 56.1 x 1000 x A3
A1: Proportion of monomers having hydroxyl groups in all monomers used for production of specific (meth)acrylic polymer (A) (unit: % by mass)
A2: Molecular weight of monomer having hydroxyl group used for producing specific (meth)acrylic polymer (A) A3: Number of hydroxyl groups contained in one molecule of monomer having hydroxyl group

When there are two or more types of monomers having a hydroxyl group used in the production of the specific (meth)acrylic polymer (A), the hydroxyl value of each monomer is calculated according to the above formula. After that, add up the obtained values 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. It is preferably in the following range, more preferably in the range of 1 mgKOH/g to 20 mgKOH/g, and even more preferably in the range of 2 mgKOH/g to 10 mgKOH/g.
When the acid value of the specific (meth)acrylic polymer (A) is within the above range, there is a tendency that a pressure-sensitive adhesive layer having a better balance between low-speed peel strength and high-speed peel strength can be formed.

The acid value of the specific (meth)acrylic polymer (A) is a value determined by the following formula. In addition, in the following formulas, 56.1 is the molecular weight of KOH.
Acid value (mgKOH/g)
= {(a1/100)/a2} x 56.1 x 1000 x a3
a1: Proportion of a monomer having a carboxy group in all monomers used for producing the specific (meth)acrylic polymer (A) (unit: % by mass)
a2: Molecular weight of monomer having carboxy group used for production of specific (meth)acrylic polymer (A) a3: Number of carboxy groups contained in one molecule of monomer having 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), for each monomer, the acid value is calculated according to the above formula. After determination, the obtained values are totaled to determine the acid number.

<<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. It is preferably in the range of 9% by mass or less, more preferably in the range of 85% by mass or more and 99.9% by mass or less, even more preferably in the range of 90% by mass or more and 99.9% by mass or less, A range of 95% by mass or more and 99.9% by mass or less is particularly preferable.
As used herein, "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. When included, it means the mass of the residue after removing the solvent from the pressure-sensitive adhesive composition.

<<Method for producing 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) is, for example, a known polymerization method represented by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method, and polymerizes the above-described monomers. It can be manufactured by Further, the specific (meth)acrylic polymer (A) can be produced by a known polymerization method represented by, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. After producing a (meth) acrylic polymer by polymerizing a monomer having no .
As the polymerization method, the solution polymerization method is preferable in that the processing steps are relatively simple and can be performed in a short period of time when preparing the pressure-sensitive adhesive composition of the present invention after production.

In the solution polymerization method, generally, a predetermined organic solvent, monomers, a polymerization initiator, and optionally a chain transfer agent are charged in a polymerization tank, and stirred at the reflux temperature of the organic solvent in a nitrogen stream. Heat and react for several hours while stirring. In this case, at least part of the organic solvent, monomer, polymerization initiator and/or chain transfer agent may be added sequentially.

Organic solvents 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 specific examples of the organic solvent used during the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic hydrocarbon compounds typified by aromatic naphtha, fats typified by n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and turpentine. or alicyclic hydrocarbon compounds, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate. Ester compounds, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, and ketone compounds represented by methyl cyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ethers and glycol ether compounds typified by diethylene glycol monobutyl ether, and methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t- Alcohol compounds represented by butyl alcohol are mentioned.

In the production of the specific (meth)acrylic polymer (A), it is preferable to use an organic solvent that is unlikely to cause chain transfer during the polymerization reaction of aromatic hydrocarbon compounds, ester compounds, ketone compounds, and the like. ) At least one selected from the group consisting of ethyl acetate, toluene, and methyl ethyl ketone is preferably used from the viewpoint of the solubility of the acrylic polymer (A), ease of polymerization reaction, and the like.

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

Examples of the polymerization initiator include organic peroxides, azo compounds, and the like, which are used in ordinary solution polymerization methods.
Examples of organic peroxides include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, carbonate, t-butyl peroxypivalate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4 -di-t-butylperoxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane.
Examples of azo compounds include 2,2'-azobisisobutyronitrile [AIBN], 2,2'-azobis(2,4-dimethylvaleronitrile) [ABVN], 2,2'-azobis(4- methoxy-2,4-dimethylvaleronitrile), 1,1′-azobis(cyclohexane-1-carbonitrile), and 2,2′-azobis(isobutyrate)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, particularly preferably an azo compound.

At the time of the polymerization reaction, only one type of polymerization initiator may be used, or two or more types may be used.

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

If necessary, a chain transfer agent may be used in the production of the specific (meth)acrylic polymer (A).
Examples of chain transfer agents include cyanoacetic acid, cyanoacetic acid alkyl ester compounds having 1 to 8 carbon atoms, bromoacetic acid, bromoacetic acid alkyl ester compounds having 1 to 8 carbon atoms, α-methylstyrene, anthracene, phenanthrene, and fluorene. , and aromatic compounds represented by 9-phenylfluorene, aromatic nitro compounds represented by p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and p-nitrotoluene, benzoquinone and Benzoquinone derivatives typified by 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives typified by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane Halogenated hydrocarbon compounds typified by , tribromoethylene, trichlorethylene, bromotrichloromethane, tribromomethane, and 3-chloro-1-propene; aldehyde compounds typified by chloral and furaldehyde; alkyls having 1 to 18 carbon atoms; Mercaptan compounds, aromatic mercaptan compounds represented by thiophenol and toluene mercaptan, mercaptoacetic acid, alkyl ester compounds of mercaptoacetic acid having 1 to 10 carbon atoms, hydroxyalkyl mercaptan compounds having 1 to 12 carbon atoms, and pinene and terpinolene Representative terpene compounds are 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. ) can be appropriately set according to the molecular weight of the product.

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

[Carboxy-modified silicone compound (B)]
The pressure-sensitive adhesive composition of the present invention contains a carboxy-modified silicone compound (B). In addition, the content of the carboxy-modified silicone compound (B) in the pressure-sensitive adhesive composition of the present invention is 0.05 parts by mass or more with respect to 100 parts by mass of the specific (meth)acrylic polymer (A) described above. It is in the range of parts by mass or less.
The pressure-sensitive adhesive composition of the present invention may contain only one type of carboxy-modified silicone compound (B), or may contain two or more types.

Carboxy-modified silicone compound (B) is not particularly limited.
As the carboxy-modified silicone compound (B), for example, a silicone compound in which an organic group having a carboxy group is introduced into a part of the side chain of the main polysiloxane chain, and a Examples include silicone compounds into which an organic group having a carboxy group has been introduced, and silicone compounds into which an organic group having a carboxy group has been introduced to one end of the main polysiloxane chain.
As the carboxy-modified silicone compound (B), a silicone compound in which an organic group having a carboxy group is introduced into a part of the side chain of the main polysiloxane chain is preferable.
Examples of the organic group having a carboxy group include alkyl groups having a carboxy group such as 2-carboxyethyl group, 2-carboxypropyl group and 3-carboxypropyl group, and alkylene oxide groups.

Examples of the carboxy-modified silicone compound (B) include a compound having a structure represented by the following formula (a), a compound having a structure represented by the formula (b), and the like.
In formulas (a) and (b), R represents any organic group. Optional organic groups include, for example, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 18 carbon atoms. In formulas (a) and (b), x is the number of repeating dimethylsiloxane structural units and represents an integer of 1-100. In formula (b), y is the number of repeating methylsiloxane structural units having an organic group having a carboxyl group, and represents an integer of 1-100.

An example of a commercially available carboxy-modified silicone compound having a structure represented by formula (a) is DOWSIL (registered trademark) BY16-750 [trade name, viscosity: 180 mm ² /s, functional group equivalent: 750 g/mol, Dow Toray Industries, Inc.], X-22-162C [trade name, viscosity: 220 mm ² /s, functional group equivalent: 2300 g/mol, Shin-Etsu Chemical Co., Ltd.] and the like.

An example of a commercially available carboxy-modified silicone compound having a structure represented by formula (b) is DOWSIL (registered trademark) BY16-880 [trade name, viscosity: 2500 mm ² /s, functional group equivalent: 3500 g/mol, Dow Toray Industries, Inc.], X-22-3701E [trade name, viscosity: 2000 mm ² /s, functional group equivalent: 4000 g/mol, Shin-Etsu Chemical Co., Ltd.] and the like.

<<Viscosity of carboxy-modified silicone compound (B)>>
^The viscosity of the ^carboxy - ^modified silicone compound (B) ^is not particularly limited. /s or more and 4000 mm ² /s or less, and particularly preferably 150 mm ² /s or more and 3000 mm ² /s or less.
When the viscosity of the carboxy-modified silicone compound (B) is 100 mm ² /s or more, the carboxy-modified silicone compound (B) is more likely to be localized near the interface between the adhesive layer and the adherend. Therefore, the formed pressure-sensitive adhesive layer tends to have a better balance between low-speed peel strength and high-speed peel strength.

The viscosity of the carboxy-modified silicone compound (B) means dynamic viscosity at 25°C. Viscosity as used herein is a value of kinematic viscosity measured using a capillary viscometer according to a method conforming to JIS K7367-1:2002.

<<Functional group equivalent of carboxy-modified silicone compound (B)>>
The functional group equivalent weight of the carboxy-modified silicone compound (B) is not particularly limited, but for example, it is preferably 300 g/mol or more, more preferably 300 g/mol or more and 10000 g/mol or less, and 500 g/mol. It is more preferably in the range of 8000 g/mol or more, and particularly preferably in the range of 600 g/mol or more and 5000 g/mol or less.
When the functional group equivalent of the carboxy-modified silicone compound (B) is 300 g/mol or more, the carboxy groups of the carboxy-modified silicone compound (B) are not too many, so when forming the pressure-sensitive adhesive layer, the carboxy-modified silicone compound Before (B) is localized near the surface of the film (so-called near the interface with the adherend), the carboxy groups in the carboxy-modified silicone compound (B) and the isocyanate groups in the isocyanate cross-linking agent (B) is more inhibited from reacting with and forming an amide bond. Therefore, the formed pressure-sensitive adhesive layer tends to have a better balance between low-speed peel strength and high-speed peel strength.

As used herein, the term "functional group equivalent" indicates the molecular weight per carboxyl group in a compound.

<<Content of carboxy-modified silicone compound (B)>>
The content of the carboxy-modified silicone compound (B) in the pressure-sensitive adhesive composition of the present invention is in the range of 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic polymer (A). , preferably in the range of 0.1 parts by mass or more and 5 parts by mass or less, more preferably in the range of 0.3 parts by mass or more and 3 parts by mass or less, and 0.3 parts by mass or more and 1 part by mass or less More preferably, it is in the range of 0.3 parts by mass or more and 0.7 parts by mass or less.
The content of the carboxy-modified silicone compound (B) in the pressure-sensitive adhesive composition of the present invention is 0.05 parts by mass or more relative to 100 parts by mass of the specific (meth)acrylic polymer (A). positively contains the carboxy-modified silicone compound (B).
When the content of the carboxy-modified silicone compound (B) in the pressure-sensitive adhesive composition of the present invention is 5 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic polymer (A), low-speed peeling force and high-speed There is a tendency that a pressure-sensitive adhesive layer having a good balance with peel strength can be formed.

In a preferred embodiment of the pressure-sensitive adhesive composition of the present invention, the viscosity of the carboxy-modified silicone compound (B) is in the range of 100 mm ² /s or more and 5000 mm ² /s or less, and the carboxy-modified silicone compound (B) An embodiment in which the content is in the range of 0.3 parts by mass or more and 0.7 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic polymer (A) is exemplified.
Further, as a preferred embodiment of the pressure-sensitive adhesive composition of the present invention, the functional group equivalent of the carboxy-modified silicone compound (B) is in the range of 300 g/mol or more and 10000 g/mol or less, and the carboxy-modified silicone compound (B ) is in the range of 0.3 parts by mass or more and 0.7 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic polymer (A).

[Isocyanate-based cross-linking agent (C)]
The pressure-sensitive adhesive composition of the present invention contains an isocyanate-based cross-linking agent (C).
As used herein, "isocyanate-based cross-linking agent (C)" refers to a compound having two or more isocyanate groups in the molecule (so-called polyisocyanate compound).

The isocyanate-based cross-linking agent (C) is not particularly limited.
Examples of the isocyanate-based cross-linking agent (C) include aromatic polyisocyanate compounds such as xylylene diisocyanate (XDI), diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), and pentamethylene. Aliphatic or alicyclic polyisocyanate compounds such as diisocyanate (PDI), isophorone diisocyanate, hydrogenated products of aromatic polyisocyanate compounds, and the like.
Further, the isocyanate-based cross-linking agent (C) includes dimers, trimers, or pentamers of the above polyisocyanate compounds, adducts of the above polyisocyanate compounds and polyol compounds such as trimethylolpropane, and the above polyisocyanates. Also included are biuret forms of compounds.
Examples of the isocyanate-based cross-linking agent (C) include compounds having two or more isocyanate groups, a polysiloxane structure and an alkylene oxide structure in the molecule (so-called silicone-based polyisocyanate compounds).
Specific examples of the silicone-based polyisocyanate compound include the exemplary silicone-based isocyanate compounds (C) described in paragraphs [0102] to [0118] of JP-A-2019-35066.

Among these, hexamethylene diisocyanate is preferable as the isocyanate-based cross-linking agent (C).
When the isocyanate-based cross-linking agent (C) is hexamethylene diisocyanate, there is a tendency that a pressure-sensitive adhesive layer having a peel strength more suitable for use as a protective film can be formed.

A commercial item can be used as an isocyanate type crosslinking agent (C).
Examples of commercially available isocyanate cross-linking agents (C) include "Coronate (registered trademark) HX", "Coronate (registered trademark) HL-S", "Coronate (registered trademark) L", "Coronate (registered trademark) L-45E", "Coronate (registered trademark) 2031", "Coronate (registered trademark) 2030", "Coronate (registered trademark) 2234", "Coronate (registered trademark) 2785", "Aquanate (registered trademark) 200" , and "Aquanate (registered trademark) 210" [above, Tosoh Corporation], "Sumidule (registered trademark) N3300", "Desmodur (registered trademark) N3400", and "Sumidule (registered trademark) N75" [The above, Sumika Covestro Urethane Co., Ltd.], "Duranate (registered trademark) E-405-80T", "Duranate (registered trademark) AE700-100", "Duranate (registered trademark) 24A-100", and " Duranate (registered trademark) TSE-100” [Asahi Kasei Corporation], and “Takenate (registered trademark) D-110N”, “Takenate (registered trademark) D-120N”, “Takenate (registered trademark) M- 631N”, “MT-Olestar (registered trademark) NP1200”, and “STABIO (registered trademark) XD-340N” [all of Mitsui Chemicals, Inc.].

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

The content of the isocyanate-based cross-linking agent (C) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, but for example, 0.1 parts by mass with respect to 100 parts by mass of the specific (meth)acrylic polymer (A) It is preferably in the range of 7.0 parts by mass or less, more preferably in the range of 0.3 parts by mass or more and 7.0 parts by mass or less, and in the range of 0.5 parts by mass or more and 5.0 parts by mass or less. is more preferable.
The content of the isocyanate-based cross-linking agent (C) in the pressure-sensitive adhesive composition of the present invention is 0.1 parts by mass or more relative to 100 parts by mass of the specific (meth)acrylic polymer (A). The pressure-sensitive adhesive layer does not exhibit an excessively high high-speed peel strength, and tends to have a better balance between the low-speed peel strength and the high-speed peel strength.
The content of the isocyanate-based cross-linking agent (C) in the pressure-sensitive adhesive composition of the present invention is 7.0 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic polymer (A). The pressure-sensitive adhesive layer does not exhibit excessively low low-speed peel strength and tends to have a better balance between low-speed and high-speed peel strength.

[Organic solvent]
The pressure-sensitive adhesive composition of the 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 those similar to 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.

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

[Polyether-modified silicone compound]
The pressure-sensitive adhesive composition of the 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, a silicone compound in which an alkylene oxide structure having a hydroxyl group at the end is bonded to a part of the side chain of the polysiloxane chain, which is the 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 thereto, and a silicone compound having an alkylene oxide structure having a terminal hydroxyl group bonded to both ends of a polysiloxane chain that is the main chain [hereinafter , Also referred to as a "specific polyether-modified silicone compound". ] is preferable.

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

When the specific polyether-modified silicone compound contains structural units derived from dialkylsiloxane and structural units derived from alkylsiloxane to which an alkylene oxide structure having a terminal hydroxyl group is bonded, the number of structural units derived from dialkylsiloxane is preferably 100 or less, more preferably 1-80.
In addition, the number of structural units derived from an alkylsiloxane to which an alkylene oxide structure having a terminal hydroxyl group is bonded is preferably 2-100, more preferably 2-80.

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

In formula (A), p is the number of repeating dimethylsiloxane structural units and represents an integer of 0 to 100, q is the number of repeating methylpropylene siloxane structural units having a polyethylene oxide chain, and is 2 to represents an integer of 100, a is the number of repeating ethylene oxide structural units and represents an integer of 1-100.
When the compound represented by formula (A) is an aggregate of a plurality of compounds, p, q, and a are average values of the compound aggregate and are rational numbers.

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

A commercial item can be used as a compound represented by Formula (A).
Examples of commercially available products of the compound represented by formula (A) include "DOWSIL (registered trademark) SF-8428", "DOWSIL (registered trademark) FZ-2162", "DOWSIL (registered trademark) SH-3773M", "DOWSIL (registered trademark) FZ-77", "DOWSIL (registered trademark) FZ-2104", "DOWSIL (registered trademark) FZ-2110", "DOWSIL (registered trademark) L-7001", "DOWSIL (registered trademark) L-7002", "DOWSIL (registered trademark) SH-3749", etc. [the above are Dow Toray Industries, Inc.].

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

A commercial item can be used as a compound represented by Formula (B).
Examples of commercially available products of the compound represented by formula (B) include "DOWSIL (registered trademark) BY-16-201", "DOWSIL (registered trademark) SF-8427", etc. ] is mentioned.

The weight average molecular weight of the polyether-modified silicone compound is not particularly limited. 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 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 in the pressure-sensitive adhesive composition of the present invention is not particularly limited. (A) With respect to 100 parts by mass, it is preferably in the range of 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably in the range of 0.1 parts by mass or more and 1.5 parts by mass or less. , 0.1 parts by mass or more and 1.0 parts by mass or less.

[Crosslinking 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 catalysts can be used.
Examples of cross-linking catalysts include organometallic compounds typified by dioctyltin dilaurate (DOTDL) and 1,3-diacetoxytetrabutylstannoxane, and tertiary amines typified by triethylenediamine and N-methylmorpholine. compound.

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

[Other ingredients]
The pressure-sensitive adhesive composition of the present invention may optionally contain components other than those described above (so-called other components) as long as the effects of the present invention are not impaired.
Other components include polymers other than the specific (meth)acrylic polymer (A), cross-linking agents other than isocyanate-based cross-linking agents (e.g., metal chelate-based cross-linking agents), antioxidants, colorants (e.g., dyes and pigments), light stabilizers (eg, 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 within the range in which 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 with a good balance between low-speed peel strength and high-speed peel strength. Problems such as peeling and displacement from the adherend are unlikely to occur, protection is not required, and an adhesive layer that can be peeled off from the adherend efficiently can be formed to protect the optical member. 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 includes, for example, members constituting devices (so-called optical devices) such as image display devices and input devices, and members used in these devices.
Specific examples of optical members include polarizing plates, AG (Anti-Glare) polarizing plates, wave plates, retardation plates including wave plates such as 1/2 and 1/4 wave plates, viewing angle compensation films, optical compensation films, and luminance enhancement. Films, light guide plates, reflective films, antireflection films, transparent conductive films such as ITO (Indium-Tin Oxide) films, prism sheets, lens sheets, diffusion plates, and the like.
Materials for optical members include polyethylene-based resin, polyester-based resin, acetate-based resin (for example, triacetyl cellulose resin), polyethersulfone-based resin, polycarbonate-based resin, polyamide-based resin, polyimide-based resin, polyolefin-based resin, Resins such as acrylic resins, vinyl chloride resins, ABS (Acrylonitrile Butadiene Styrene) resins, and fluorine resins can be used.

[Protective film for optical members]
The optical member protective film of the present invention (hereinafter also simply referred to as "protective film") comprises a base material and an adhesive formed on the base material and formed from the above-described pressure-sensitive adhesive composition of the present invention. and an agent layer. That is, in the protective film of the present invention, the substrate and the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention are laminated.
Since the protective film of the present invention has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention, it has a good balance between low-speed peel strength and high-speed peel strength. In other words, the protective film of the present invention, after being attached to the surface of the adherend, is less likely to cause problems such as peeling and displacement from the adherend while protection is required, and protection is not required. When peeling from the adherend, it can be peeled off efficiently.

The substrate is not particularly limited as long as the adhesive layer can be formed on the substrate.
Examples of base materials include polyethylene-based resins, polyester-based resins, acetate-based resins (e.g., triacetylcellulose resin), polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, Films containing resins such as acrylic resins, vinyl chloride resins, ABS (Acrylonitrile Butadiene Styrene) resins, fluorine resins, and the like can be mentioned.
For example, from the viewpoint of inspection and management of optical members by fluoroscopy, base materials include polyester-based resins, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, and polyolefin-based resins. , and acrylic resins.
Further, for example, from the viewpoint of surface protection performance, a film containing a polyester-based resin is preferable, and in consideration 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 substrate may be partially or wholly patterned.

The thickness of the substrate is not particularly limited, but is generally 500 μm or less, preferably 300 μm or less, more preferably 200 μm or less.
The lower limit of the thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of the strength of the protective film.

An antistatic layer may be provided on one or both sides of the substrate. In addition, the surface of the base material on which the pressure-sensitive adhesive layer is provided may be 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.

A method for forming the pressure-sensitive adhesive layer is not particularly limited, and a commonly used method can be employed.
As a 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 on a substrate as it is or, if necessary, after being diluted with a solvent, to form a coating film. Next, by drying the formed coating film, an adhesive film is formed on the substrate. Next, by curing the adhesive film formed on the substrate, an adhesive layer is formed on the substrate.

In the protective film of the present invention, the exposed pressure-sensitive adhesive layer may be protected with a release film. The release film is not particularly limited as long as it can be easily peeled off from the adhesive layer. is mentioned. Examples of resin films include polyester films typified by polyethylene terephthalate (PET) films. Examples of release agents include fluorine-based resins, paraffin waxes, silicones, long-chain alkyl group compounds, and the like.
The peeling film protects the surface of the pressure-sensitive adhesive layer until the protective film is put to practical use, and is peeled off during use.

As another method for forming a pressure-sensitive adhesive layer on a substrate, for example, the following method can be adopted.
The pressure-sensitive adhesive composition of the present invention, as it is, or diluted with a solvent if necessary, is applied on a release film such as paper or resin film that has been surface-treated with a release agent, and then released. A coating film is formed on the film. Next, by drying the formed coating film, an adhesive film is formed on the release film. Next, the exposed surface of the formed adhesive film is brought into contact with the substrate and pressed to transfer the adhesive film to the substrate, thereby forming the adhesive film on the substrate. Next, by curing the formed adhesive film, an adhesive layer is formed on the substrate.

The method of applying the pressure-sensitive adhesive composition onto the substrate or release film is not particularly limited, and examples include gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, knife coaters, spray coaters, bar A known method using a coater, an applicator, or the like can be mentioned.
The amount of the adhesive composition to be applied onto the substrate or release film is appropriately set according to the thickness of the 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), surface roughness of the adherend, and the like.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but generally ranges from 1 μm to 100 μm, preferably from 5 μm to 50 μm, and more preferably from 10 μm to 30 μm.

The method for drying the coating film formed on the base material or the release film is not particularly limited, and examples thereof include natural drying, heat drying, hot air drying, vacuum drying and the like.
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 conditions includes conditions 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 adhesive composition to form an adhesive layer.

The adhesive force (so-called peel force) of the adhesive layer when the protective film attached to the adherend is peeled off at 180° is 0 when the peel speed is 0.3 m / min (i.e., low speed peel). It is preferably 0.05 N/25 mm or more, more preferably 0.07 N/25 mm or more, and even more preferably 0.10 N/25 mm or more.

The adhesive strength (so-called peeling force) of the adhesive layer when the protective film attached to the adherend is peeled off at 180° is 1.00 N when the peeling speed is 30 m / min (i.e., high-speed peeling). /25 mm, more preferably less than 0.80 N/25 mm, and even more preferably less than 0.60 N/25 mm.

In this specification, a pressure-sensitive adhesive layer having a good balance between low-speed peel strength and high-speed peel strength is defined as a value obtained by dividing the value of low-speed peel strength by the value of high-speed peel strength (i.e., "low-speed peel strength/high-speed Evaluate based on "Peel force").
The "low speed peel strength/high speed peel strength" is preferably 0.10 or more, more preferably 0.15 or more, and even more preferably 0.20 or more.

EXAMPLES Hereinafter, the present invention will be described more specifically 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.

[Production of (meth)acrylic polymer A]
[Production Example A-1]
70.0 parts by mass of ethyl acetate [organic solvent] was introduced into a reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet 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] were added. , 4-hydroxybutyl acrylate [4HBA; a monomer having a hydroxyl group] 3.0 parts by mass, and acrylic acid [AA; a monomer having a carboxyl group] 0.7 parts by mass are added and mixed to obtain a monomer A mixture.
25.0 mass % of this monomer mixture was added into the reaction vessel. Next, 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 under a nitrogen atmosphere. , the temperature of the contents in the reaction vessel was raised to 85° C. to initiate the initial reaction.
After the initial reaction is almost completed, the remaining monomer mixture of 75.0% by mass and a mixture of 20.0 parts by mass of ethyl acetate and 0.02 parts by mass of AIBN are added to the reaction vessel over about 2 hours. The contents in the reaction vessel were allowed to react while being added successively, and after the addition was completed, the reaction was further allowed to proceed for 2 hours to obtain a reactant (a1).
Thereafter, a solution prepared by dissolving 0.25 parts by mass of t-butyl peroxypivalate (polymerization initiator) in 25.0 parts by mass of ethyl acetate was added dropwise to the reactant (a1) in the reaction vessel over 1 hour. After completion of the dropwise addition, the reaction was further performed for 1.5 hours to obtain a reactant (a2). The obtained reactant (a2) was diluted with ethyl acetate to obtain a solution of (meth)acrylic polymer A-1 having a solid concentration of 45% by mass.

The term "solid content concentration" as used herein means the mass proportion of the (meth)acrylic polymer A-1 in the solution of the (meth)acrylic polymer A-1.
The same applies to each solution of (meth)acrylic polymers A-2 to A-6 below.

[Production Examples A-2 and A-4 to A-6]
In Production Examples A-2 and A-4 to A-6, the monomer composition of (meth)acrylic polymer A was changed to the monomer composition shown in Table 1, and the amount of organic solvent used. And by adjusting at least one of the amount of the polymerization initiator used, the weight average molecular weight (Mw) of the (meth)acrylic polymer A is adjusted to the weight average molecular weight (Mw) shown in Table 1, The same operation as in Production Example A-1 was performed to obtain solutions of (meth)acrylic polymers A-2 and A-4 to A-6 having a solid content concentration of 45% by mass.

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

(Meth) acrylic polymers A-1 to A-6 monomer composition (unit: mass%), hydroxyl value (unit: mgKOH/g), acid value (unit: mgKOH/g), weight average molecular weight [ Table 1 shows Mw, unit: 10,000 (denoted as "×10 ⁴ in the table)" and glass transition temperature (Tg, unit: °C).

The weight average molecular weights (Mw) of the (meth)acrylic polymers A-1 to A-6 are determined in the same manner as the weight average molecular weight (Mw) of the specific (meth)acrylic polymer (A) described above. method.
The glass transition temperature (Tg) of the (meth)acrylic polymers A-1 to A-6 is the same as the calculation method of the glass transition temperature (Tg) of the specific (meth)acrylic polymer (A) described above. calculated by the method.

The hydroxyl value and acid value of the (meth)acrylic polymers A-1 to A-6 are calculated in the same manner as the method for calculating the hydroxyl value and acid value of the specific (meth)acrylic polymer (A), respectively. Calculated by

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

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

Among the (meth)acrylic polymers A-1 to A-6 obtained above, the (meth)acrylic polymers A-1 to A-5 are the specific (meth)acrylic polymers in the present invention. It corresponds to (A).

Details of each monomer listed 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 [a monomer having a hydroxyl group]
"AA": acrylic acid [monomer having a carboxy group]

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

[Production of silicone-based polyisocyanate compound X]
Takenate (registered trademark) 500 [trade name, xylylene diisocyanate (XDI), Mitsui Chemicals, Inc.] 118 was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, a reflux condenser, and a dropping funnel. 0 parts by mass and 82.0 parts by mass of DOWSIL (registered trademark) SH-3773M [trade name, polyether-modified silicone compound, Dow Toray Industries, Inc.] were charged, and the air in the flask was replaced with nitrogen gas. After that, the temperature inside the flask was raised to 50°C. Next, while maintaining the temperature in the flask at 50° C., the content in the flask was stirred for 6 hours to obtain a silicone-based polyisocyanate compound X, which is an isocyanate-based cross-linking agent.

[Preparation of adhesive composition]
[Example 1]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as a solid content), 0.5 parts by mass of DOWSIL (registered trademark) BY16-880 [trade name, Dow Toray Industries, Inc.] which is a carboxy-modified silicone compound (B), and polyether-modified silicone 0.3 parts by mass of the compound DOWSIL (registered trademark) SH-3773M [trade name, compound represented by formula (A), Dow Toray Industries, Inc.] was charged, and the liquid temperature of the contents in the flask was adjusted. was stirred for 4 hours while the temperature was maintained at around 25°C.
Next, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestro Urethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as solid content) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Example 1.

[Examples 2 and 3]
In Examples 2 and 3, the same operation as in Example 1 was performed except that the type of the specific (meth)acrylic polymer (A) was changed to the type shown in Table 2, and each of Examples 2 and 3 An adhesive composition was obtained.

[Example 4]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-4, which is the specific (meth)acrylic polymer (A). (100 parts by mass as solid content), 0.5 parts by mass of DOWSIL (registered trademark) BY16-880 [trade name, Dow Toray Industries, Inc.] which is a carboxy-modified silicone compound (B), and polyether-modified silicone 0.3 parts by mass of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a compound, was charged, and the liquid temperature of the contents in the flask was maintained at around 25°C for 4 hours. Stirred.
Next, in the flask, 15 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent (C), was placed in the flask. 0 parts by mass (5.0 parts by mass as a solid content) and 0.02 parts by mass of dioctyltin dilaurate (DOTDL), which is a cross-linking catalyst, were added and sufficiently stirred to obtain the pressure-sensitive adhesive composition of Example 4. got stuff

[Example 5]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-5, which is the specific (meth)acrylic polymer (A). (100 parts by mass as a solid content), 0.5 parts by mass of DOWSIL (registered trademark) BY16-880 [trade name, Dow Toray Industries, Inc.] which is a carboxy-modified silicone compound (B), and polyether-modified silicone 0.3 parts by mass of the compound DOWSIL (registered trademark) SH-3773M [trade name, compound represented by formula (A), Dow Toray Industries, Inc.] was charged, and the liquid temperature of the contents in the flask was adjusted. was stirred for 4 hours while the temperature was maintained at around 25°C.
Next, in the flask, 15 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate-based cross-linking agent (C), was placed in the flask. 0 parts by mass (5.0 parts by mass as solid content) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Example 5.

[Examples 6 to 8]
In Examples 6 to 8, the same operation as in Example 1 was performed, except that the blending amount of the carboxy-modified silicone compound (B) was changed to the blending amount shown in Table 2, and the pressure-sensitive adhesives of Examples 6 to 8 were prepared. A composition was obtained.

[Examples 9 and 10]
In Examples 9 and 10, the same operation as in Example 1 was carried out, except that the type of carboxy-modified silicone compound (B) was changed to the type shown in Table 2, and each pressure-sensitive adhesive composition of Examples 9 and 10 was prepared. got

[Example 11]
In Example 11, the same operation as in Example 1 was performed, except that DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a polyether-modified silicone compound, was not blended. A pressure-sensitive adhesive composition of Example 11 was obtained.

[Example 12]
In Example 12, the blending amount of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a polyether-modified silicone compound, was changed from "0.3 parts by mass" to "0.7 parts by mass." A pressure-sensitive adhesive composition of Example 12 was obtained by performing the same operation as in Example 1, except for changing to

[Example 13]
In Example 13, instead of blending 0.3 parts by mass of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.) as the polyether-modified silicone compound, DOWSIL (registered trademark) SH-8400 was used. The same procedure as in Example 1 was carried out, except that 0.3 parts by mass of [trade name, silicone compound bonded with an alkylene oxide structure having an acetyl group at the end, Dow Toray Industries, Inc.] was added. Thirteen adhesive compositions were obtained.

[Examples 14 and 15]
In Examples 14 and 15, the same operation as in Example 1 was performed, except that the blending amount of the isocyanate cross-linking agent (C) was changed to the blending amount shown in Table 2, and each pressure-sensitive adhesive of Examples 14 and 15 A composition was obtained.

[Examples 16 to 18]
In Examples 16 to 18, the same operation as in Example 1 was performed except that the type of isocyanate cross-linking agent (C) was changed to the type shown in Table 2, and each pressure-sensitive adhesive composition of Examples 16 to 18 got

[Example 19]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as solid content), 0.5 parts by mass of DOWSIL (registered trademark) BY16-880 [trade name, Dow Toray Industries, Inc.] which is a carboxy-modified silicone compound (B), and polyether-modified silicone 0.3 parts by mass of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a compound, was charged, and the liquid temperature of the contents in the flask was maintained at around 25°C for 4 hours. Stirred.
Then, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as a solid content) and 0.45 parts by mass of the silicone-based polyisocyanate compound X, which is the isocyanate-based cross-linking agent (C), are added and sufficiently stirred to obtain the Nineteen adhesive compositions were obtained.

[Example 20]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as solid content), 0.5 parts by mass of DOWSIL (registered trademark) BY16-880 [trade name, Dow Toray Industries, Inc.] which is a carboxy-modified silicone compound (B), and polyether-modified silicone 0.3 parts by mass of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a compound, was charged, and the liquid temperature of the contents in the flask was maintained at around 25°C for 4 hours. Stirred.
Then, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as a solid content), and aluminum chelate A (trade name, aluminum trisacetylacetonate, Kawaken Fine Chemicals Co., Ltd.), which is a metal chelate-based cross-linking agent as another cross-linking agent. 1 part by mass was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Example 20.

[Comparative Example 1]
In Comparative Example 1, instead of blending 100 parts by mass of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A), (meth)acrylic polymer A as a comparative polymer was added. A pressure-sensitive adhesive composition of Comparative Example 1 was obtained in the same manner as in Example 1, except that 100 parts by mass of -6 was added.

[Comparative Example 2]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as a solid content) were charged, and the contents in the flask were stirred for 4 hours while maintaining the liquid temperature around 25°C.
Next, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestro Urethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as solid content) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 2.

[Comparative Example 3]
In Comparative Example 3, a pressure-sensitive adhesive composition of Comparative Example 3 was obtained in the same manner as in Example 1, except that the amount of the carboxy-modified silicone compound (B) was changed to the amount shown in Table 3. .

[Comparative Example 4]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as a solid content), and ARUFON (registered trademark) UC-3510, an acrylic oligomer having a carboxy group as a comparative compound for the carboxy-modified silicone compound (B) [trade name, weight average molecular weight: 2000, Toa Synthetic Co., Ltd.] 0.5 parts by mass, and DOWSIL (registered trademark) SH-3773M, which is a polyether-modified silicone compound [trade name, compound represented by formula (A), Dow Toray Industries, Inc.] 0.5 parts by mass. 3 parts by mass were charged, and the contents in the flask were stirred for 4 hours while maintaining the liquid temperature around 25°C.
Then, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as solid content) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 4.

[Comparative Example 5]
A four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel was charged with 222.2 mass of a solution of (meth)acrylic polymer A-1, which is the specific (meth)acrylic polymer (A). (100 parts by mass as solid content) and 0.5 parts by mass of DOWSIL (registered trademark) SH-3773M (trade name, Dow Toray Industries, Inc.), which is a polyether-modified silicone compound, were charged, and the contents in the flask were The contents were stirred for 4 hours while maintaining the liquid temperature around 25°C.
Then, in the flask, 6 of a diluted solution of Desmodur (registered trademark) N3400 [trade name, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestrourethane Co., Ltd.], which is an isocyanate cross-linking agent (C), was placed in the flask. 0 parts by mass (2.0 parts by mass as solid content) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Comparative Example 5.

[Comparative Example 6]
In Comparative Example 6, instead of the isocyanate-based cross-linking agent (C), TETRAD (registered trademark)-X (trade name, Mitsubishi Gas Chemical Co., Ltd.), which is an epoxy-based cross-linking agent, was added as a comparative cross-linking agent. , the same operation as in Example 1 was performed to obtain a pressure-sensitive adhesive composition of Comparative Example 6.

In Tables 2 and 3, "-" means that the corresponding component is not included.
All compounding amounts in Tables 2 and 3 are solid content conversion values.
In Table 2, "silicone-based polyisocyanate compound X" is indicated as "compound X".

Details of each component listed in Tables 2 and 3 are as follows.
<Carboxy-modified silicone compound (B)>
"BY16-880" [trade name: DOWSIL (registered trademark) BY16-880, Dow Toray Industries, Inc.]
: Carboxy-modified silicone compound having a structure represented by formula (b) "X-22-3701E" [trade name, Shin-Etsu Chemical Co., Ltd.]
: Carboxy-modified silicone compound having a structure represented by formula (b) "X-22-162C" [trade name, Shin-Etsu Chemical Co., Ltd.]
: A carboxy-modified silicone compound having a structure represented by formula (a)

<Comparative compound>
“UC-3510” [trade name: ARUFON (registered trademark) UC-3510, weight average molecular weight: 2000, Toagosei Co., Ltd.]
: Acrylic oligomer with carboxy group

<Isocyanate-based cross-linking agent (C)>
"N3400" [trade name: Desmodur (registered trademark) N3400, dimer of hexamethylene diisocyanate (HMDI), Sumika Covestro Urethane Co., Ltd.]
"N3300" [trade name: Sumidule (registered trademark) N3300, trimer of hexamethylene diisocyanate (HMDI), Sumika Covestro Urethane Co., Ltd.]
"L-45E" [trade name: Colonate (registered trademark) L-45E, an adduct of tolylene diisocyanate (TDI) and trimethylolpropane (TMP), Tosoh Corporation]
"D-120" [trade name: Takenate (registered trademark) D-120, an adduct of xylylene diisocyanate (XDI) and trimethylolpropane (TMP), Mitsui Chemicals, Inc.]
"Compound X": silicone-based polyisocyanate compound X

<Other cross-linking agents>
"Aluminum chelate A" [trade name, aluminum trisacetylacetonate, Kawaken Fine Chemicals Co., Ltd.]: metal chelate-based cross-linking agent <comparative cross-linking agent>
"TETRAD-X" [trade name: TETRAD (registered trademark)-X, Mitsubishi Gas Chemical Company, Inc.]: epoxy-based cross-linking agent

[evaluation]
The following evaluation was performed using the adhesive composition prepared above.
Table 4 shows the results.

1. Peeling force <Preparation of protective film for peeling force evaluation>
A polyethylene terephthalate (PET) film (trade name: Teijin (registered trademark) Tetoron (registered trademark) film, model number: G2, thickness: 38 μm, Teijin Film Solution Co., Ltd.) as a substrate, and the amount of coating after drying. A coating film was formed by applying the pressure-sensitive adhesive composition so that the weight was 15 g/m ² . Then, the formed coating film was dried at 100° C. for 60 seconds using a hot air circulating dryer to form an adhesive film on the substrate.
Next, the exposed surface of the adhesive film formed on the base material is treated with a silicone-based release agent to form a release film [trade name: Film Binah (registered trademark) 100E-0010N023, thickness: 100 μm, Fujimori Kogyo ( Co., Ltd.], and passed through pressure nip rolls to press the adhesive film and the release film together. Then, the adhesive film was aged for 96 hours in an environment of an atmospheric temperature of 23° C. and 50% RH to obtain a protective film for peel force evaluation having a laminated structure of substrate/adhesive layer/release film.

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

-Evaluation criteria-
AA: The peel strength is 0.10 N/25 mm or more.
A: The peel strength is 0.07 N/25 mm or more and less than 0.10 N/25 mm.
B: The peel force is 0.05 N/25 mm or more and less than 0.07 N/25 mm.
C: The peel force is less than 0.05 N/25 mm.

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

-Evaluation criteria-
AA: The peel force is less than 0.60 N/25 mm.
A: The peel force is 0.60 N/25 mm or more and less than 0.80 N/25 mm.
B: The peel force is 0.80 N/25 mm or more and less than 1.00 N/25 mm.
C: The peel force is 1.00 N/25 mm or more.

(3) Balance between low-speed peel strength and high-speed peel strength The balance between the low speed peel force and the high speed peel force was evaluated based on the value of the high speed peel force.
Specifically, the value of the low-speed peel force is divided by the value of the high-speed peel force, and the balance between the low-speed peel force and the high-speed peel force is evaluated according to the following evaluation criteria based on the value rounded to the third decimal place. did.
If the evaluation result was "AA", "A", or "B", it was determined that the pressure-sensitive adhesive layer had a good balance between the low-speed peel strength and the high-speed peel strength.

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

As shown in Table 4, the above-mentioned Examples 1 to 20 in which the content of the carboxy-modified silicone compound (B) is in the range of 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer (A). It was confirmed that the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of No. 2 had a good balance between the low-speed peel strength and the high-speed peel strength.

On the other hand, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 1, in which the (meth)acrylic polymer (A) has neither a hydroxyl group nor a carboxyl group, was evaluated without peeling from the adherend. I couldn't.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 2, which does not contain the carboxy-modified silicone compound (B), has an excessively high high-speed peel strength, and the balance between the low-speed peel strength and the high-speed peel strength is not good. was confirmed.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 3 in which the content of the carboxy-modified silicone compound (B) exceeds 5 parts by mass with respect to 100 parts by mass of the specific (meth)acrylic polymer (A) , it was confirmed that the low speed peel force was excessively low and the balance between the low speed peel force and the high speed peel force was not good.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 4, which contains an acrylic oligomer having a carboxy group as a comparative compound instead of the carboxy-modified silicone compound (B) and does not contain a cross-linking agent, exhibits low-speed peeling. It was found that the force was too low and the balance between low speed and high speed peel forces was not good.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 5, which does not contain the carboxy-modified silicone compound (B) but contains the polyether-modified silicone compound, has an excessively low low-speed peel force, and the low-speed peel force and the high-speed peel force are excessively low. It was confirmed that the balance with force is not good.
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Comparative Example 6, which contains an epoxy-based cross-linking agent instead of the isocyanate-based cross-linking agent (C), has an excessively high high-speed peel strength and a poor balance between low-speed peel strength and high-speed peel strength. It was confirmed that the balance was not good.

Claims (6)

a (meth)acrylic polymer (A) having at least one of a hydroxyl group and a carboxy group;
a carboxy-modified silicone compound (B);
and an isocyanate-based cross-linking agent (C),
For an optical member protective film, wherein the content of the carboxy-modified silicone compound (B) is in the range of 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer (A) Adhesive composition. The pressure-sensitive adhesive composition for an optical member protective film according to claim 1, comprising a polyether-modified silicone compound. The pressure-sensitive adhesive composition for an optical member protective film according to claim 1 or 2, wherein the carboxy-modified silicone compound (B) has a viscosity of 100 ^mm2 /s or more. 4. The pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 3, wherein the carboxy-modified silicone compound (B) has a functional group equivalent weight of 300 g/mol or more. The pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 4, wherein the isocyanate-based cross-linking agent (C) is hexamethylene diisocyanate. An optical device comprising a substrate, and a pressure-sensitive adhesive layer provided on the substrate and formed from the pressure-sensitive adhesive composition for an optical member protective film according to any one of claims 1 to 5. Component protection film.