JP2016190902A - Adhesive composition and adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition from which an adhesive film having excellent fast peeling property after a heating treatment and having low dependency on a peeling speed can be produced, and an adhesive film.SOLUTION: The adhesive composition comprises: a (meth)acrylic polymer including a structural unit derived from a monomer having a hydroxyl group, and having a hydroxyl value of 10 mgKOH/g or more and a weight average molecular weight of 300000 or more and 1800000 or less; an isocyanate compound; and a terpene phenol-based tackifier. The content of the terpene phenol-based tackifier is 0.1 pts.mass or more and 5 pts.mass or less with respect to 100 pts.mass of the (meth)acrylic polymer; and the total hydroxyl value calculated by the following formula (1) is 10 mgKOH/g or more and 85 mgKOH/g or less. Formula (1) is represented by total hydroxyl value=A×{a/(a+c)}+C×{c/(a+c)}. In formula (1), A represents a hydroxyl value (mgKOH/g) of the (meth)acrylic polymer; C represents a hydroxyl value (mgKOH/g) of the terpene phenol-based tackifier; a represents a content of the (meth)acrylic polymer (pts.mass); and c represents a content of the terpene phenol-based tackifier (pts.mass).SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition and an adhesive film.

  When processing or transporting articles such as metal plates, painted steel plates, and synthetic resin plates, adhesive films are applied to protect the surfaces of the articles from damage, dirt, etc. . The adhesive film is peeled off from the article when protection of the article is no longer necessary. The pressure-sensitive adhesive film used here generally has a pressure-sensitive adhesive layer for attaching to an article (hereinafter also referred to as “adhered body”) on one side of a sheet-like base material.

  The pressure-sensitive adhesive layer of the pressure-sensitive adhesive film has such a degree of adhesiveness that it does not cause displacement on the surface of the adherend or fall off from the surface of the adherend while protection of the adherend is required. It is required to be easily peelable from the adherend (hereinafter also referred to as “peelability”) at the stage where the protection of the adherend becomes unnecessary.

  In addition, the adherend may be heat-treated in a state protected by an adhesive film. In general, the adhesive film is difficult to peel off from the adherend due to an increase in the adhesive force of the adhesive layer, for example, by heat treatment at 100 ° C. For this reason, the adhesive film is required to have good peelability even after heat treatment.

  In response to these requirements, Patent Document 1 discloses a pressure-sensitive adhesive composition in which a reactive oligomer is added to an acrylic polymer as a pressure-sensitive adhesive having a small increase in adhesive strength even after heat treatment. Patent Document 2 discloses a pressure-sensitive adhesive composition containing an acrylic high molecular weight copolymer having a functional group and an acrylic low molecular weight copolymer having a functional group.

JP 2003-277707 A JP 2008-38103 A

Generally, it is known that the force for peeling an adhesive film from an adherend (hereinafter also referred to as “peeling force”) varies depending on the peeling rate (hereinafter also referred to as “peeling rate dependency”). Yes. Moreover, there exists a tendency for big peeling force to be required, so that peeling speed is high. The pressure-sensitive adhesive film that has been heat-treated has an increased adhesive strength of the pressure-sensitive adhesive layer, and may be difficult to peel off from the adherend, and is also referred to as “high-speed peelability” (hereinafter, “high-speed peelability”). ) Is likely to get worse.
If the high-speed peelability is inferior, it may be possible to peel at a low speed, but peeling at a low speed is inefficient.
Therefore, the adhesive film is required to be excellent in high-speed peelability from the viewpoint of increasing the peeling speed and improving the efficiency.

Moreover, since the peeling speed of the adhesive film is not constant, depending on the peeling speed, the adhesive film may be difficult to peel from the adherend and may be damaged.
For this reason, the adhesive film is also required to have a peeling force that hardly changes even if the peeling speed changes, that is, it has a low dependence on the peeling speed.

  On the other hand, in Patent Documents 1 and 2 described above, no study has been made on the high-speed peelability after heat treatment and the peel rate dependency. In addition, when the conventional pressure-sensitive adhesive composition as described in Patent Documents 1 and 2 described above has high-speed peelability and peel-speed dependency after heat treatment are not at a level sufficient for recent requirements. I found out that

This invention is made | formed in view of the above situations, and provides the adhesive composition which can manufacture the adhesive film which is excellent in the high speed peelability after heat processing, and has low peeling rate dependence. Is an issue.
Another object of the present invention is to provide a pressure-sensitive adhesive film that includes a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition, is excellent in high-speed peelability after heat treatment, and has low peel rate dependency.

Specific means for solving the problems include the following aspects.
<1> A (meth) acrylic polymer containing a structural unit derived from a monomer having a hydroxyl group, a hydroxyl value of 10 mgKOH / g or more, and a weight average molecular weight of 300000 to 1800000, an isocyanate compound, and a terpenephenol series The content of the terpene phenolic tackifier with respect to 100 parts by mass of the (meth) acrylic polymer is 0.1 parts by mass or more and 5 parts by mass or less, and is calculated by the following formula (1). A pressure-sensitive adhesive composition having a total hydroxyl value of 10 mgKOH / g or more and 85 mgKOH / g or less.

<2> A (meth) acrylic oligomer containing a structural unit derived from a monomer having a hydroxyl group, having a hydroxyl value of 70 mgKOH / g or more and a weight average molecular weight of 1,000 to 30,000, The ratio of the (meth) acrylic oligomer to the total mass of the polymer based polymer and the (meth) acrylic oligomer is 1% by mass or more and 40% by mass or less, and the content of the terpene phenolic tackifier is the above (meta) ) The content of the terpene phenolic tackifier with respect to a total of 100 parts by mass of the acrylic polymer and the (meth) acrylic oligomer, and the total hydroxyl value calculated by the above formula (1) is the following formula: This is the total hydroxyl value calculated by (2), calculated by the following formula (2) Total hydroxyl value that is less than or equal to 15 mgKOH / g or more 85 mgKOH / g, pressure-sensitive adhesive composition according to <1>.

<3> The content of the isocyanate compound is such that the isocyanate group is 0.5 equivalent with respect to a total of 1 equivalent of the hydroxyl group contained in the (meth) acrylic polymer and the hydroxyl group contained in the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to <2>, which is an amount of 2.0 equivalent or less.

<4> The structural unit derived from a monomer having a glass transition temperature (Tg) of −50 ° C. or less when the (meth) acrylic oligomer is a homopolymer is defined as all structural units of the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to <2> or <3>, containing 50% by mass or more based on

<5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, wherein a glass transition temperature (Tg) of the (meth) acrylic polymer is −50 ° C. or lower.

<6> The pressure-sensitive adhesive composition according to any one of <1> to <5>, wherein the terpene phenol-based tackifier has a hydroxyl value of 20 mgKOH / g or more and 160 mgKOH / g or less.

A pressure-sensitive adhesive film comprising a <7> base material and a pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition according to any one of <1> to <6>.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can manufacture the adhesive film which is excellent in the high-speed peelability after heat processing and has low peeling rate dependence can be provided.
In addition, according to the present invention, it is possible to provide a pressure-sensitive adhesive film that includes the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition, is excellent in high-speed peelability after heat treatment, and has low peel rate dependency.

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

In the present specification, a numerical range indicated using “to” means a range including the numerical values described before and after “to” as a minimum value and a maximum value, respectively.
In this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. .

In this specification, the “pressure-sensitive adhesive composition” refers to a liquid or paste-like composition after mixing a (meth) acrylic polymer, an isocyanate compound, and a terpenephenol tackifier and before the crosslinking reaction is completed. Means a substance.
In the present specification, the “pressure-sensitive adhesive layer” means a substance after the crosslinking reaction of the pressure-sensitive adhesive composition is completed.

In the present specification, “(meth) acrylic polymer” or “(meth) acrylic oligomer” means a polymer in which at least a monomer as a main component is a monomer having a (meth) acryloyl group among the monomers constituting these. Or an oligomer is meant. The monomer as the main component here means a monomer having the largest content (mass%) among monomers constituting the polymer or oligomer. In an embodiment of the (meth) acrylic polymer or (meth) acrylic oligomer in the present invention, the content of the structural unit derived from the monomer having the (meth) acryloyl group as the main component is 50% by mass of the total structural unit. That's it.
In the present specification, “(meth) acryl” means both “acryl” and “methacryl”, “(meth) acrylate” means both “acrylate” and “methacrylate”, and “(meth) acryloyl” Means both “acryloyl” and “methacryloyl”.

  In this specification, the (meth) acrylic polymer and the (meth) acrylic oligomer are collectively referred to as “acrylic resin”.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention comprises a (meth) acrylic polymer having a structural unit derived from a monomer having a hydroxyl group, a hydroxyl value of 10 mgKOH / g or more, and a weight average molecular weight of 300000 to 1800000, and an isocyanate. A terpene phenolic tackifier, and a content of the terpene phenolic tackifier with respect to 100 parts by mass of the (meth) acrylic polymer is 0.1 parts by mass or more and 5 parts by mass or less, and the following formula: The total hydroxyl value calculated by (1) is 10 mgKOH / g or more and 85 mgKOH / g or less.

  By satisfy | filling the said requirements, the adhesive composition of this invention turns into an adhesive composition which can manufacture the adhesive film which is excellent in the high-speed peelability after heat processing, and has low peeling rate dependence.

In general, a tackifier (tackifier) is used by being added to an adhesive composition in order to increase adhesive strength and tack.
The inventor has a pressure-sensitive adhesive composition containing a small amount of a terpene phenol-based tackifier together with a hydroxyl group-containing (meth) acrylic polymer and an isocyanate compound. It has been found that, while exhibiting good peelability during high-speed peeling, the dependency of the adhesive force on the peeling speed can be kept low.
The reason why the pressure-sensitive adhesive composition of the present invention can exhibit such an effect is not clear, but the present inventors presume as follows.

  Generally, in an adhesive film, the adhesive force of an adhesive layer rises by heating. The increase in the adhesive force is caused by the resin becoming soft by heating and excessively spreading on the adherend. Moreover, the force (peeling force) for peeling the pressure-sensitive adhesive film from the adherend has a peeling speed dependency, and the higher the peeling speed, the larger the peeling force is required. The heated pressure-sensitive adhesive film tends to be inferior in high-speed peelability since the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is increased.

  In the pressure-sensitive adhesive composition of the present invention, a (meth) acrylic polymer having a hydroxyl value of 10 mgKOH / g or more and a small amount of terpenephenol-based tackifier that does not increase the adhesive strength or tack are contained via an isocyanate compound. Crosslinked to form a crosslinked body. In this crosslinked product, the total hydroxyl value derived from the (meth) acrylic polymer and the terpene phenolic tackifier is 10 mgKOH / g or more and 85 mgKOH / g or less, and there are many hydroxyl groups that are crosslinkable functional groups. Hard because it contains cross-linking points. If the cross-linked body is hard, the (meth) acrylic polymer portion is difficult to spread excessively on the adherend due to heating, and an increase in adhesive force due to heating is suppressed, so that it is considered that high-speed peelability is excellent.

In general, the peel rate dependency of the adhesive force is determined by the balance between the viscoelasticity of the adhesive layer and the wettability to the adherend.
In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer and the terpene phenolic tackifier are cross-linked via an isocyanate compound, so that a balance between viscoelasticity and wettability can be obtained, so that the peeling rate It is considered that the dependency is kept low.

  In the present specification, the “hydroxy value of (meth) acrylic polymer” is determined by the following calculation formula. In the following calculation formula, 56.1 is the molecular weight of KOH.

  When there are two or more monomers having a hydroxyl group used in the (meth) acrylic polymer, the hydroxyl value is obtained according to the above formula for each monomer, and the obtained values are summed to obtain the hydroxyl value. Ask.

  In this specification, the “hydroxyl value of terpene phenolic tackifier” is measured by the method of JIS K 0070: 1992. A commercially available product can be used as the terpene phenol-based tackifier. When the terpene phenol tackifier is a commercial product, the hydroxyl value described in the catalog of the commercial product is preferentially adopted.

In the pressure-sensitive adhesive composition of the present invention, the total hydroxyl value calculated by the above formula (1) is 10 mgKOH / g or more and 85 mgKOH / g or less.
The pressure-sensitive adhesive composition of the present invention is excellent in high-speed peelability after heat treatment when the total hydroxyl value calculated by the above formula (1) is 10 mgKOH / g or more.
Further, the pressure-sensitive adhesive composition of the present invention has a sufficient pressure-sensitive adhesive strength so that it does not easily fall off from the adherend when the total hydroxyl value calculated by the above formula (1) is 85 mgKOH / g or less. It can be applied to the agent layer and can also maintain excellent high-speed peelability.
The total hydroxyl value calculated by the above formula (1) is preferably 15 mgKOH / g or more. The total hydroxyl value calculated by the above formula (1) is preferably 75 mgKOH / g or less.

  The ratio of the hydroxyl value of the (meth) acrylic polymer and the hydroxyl value of the terpene phenolic tackifier in the pressure-sensitive adhesive composition of the present invention [hydroxyl value of the (meth) acrylic polymer / hydroxyl value of the terpenephenol tackifier] is From the viewpoint of further improving the high-speed peelability after the heat treatment and keeping the dependency on the peel rate lower, it is preferably 5 or more and 500 or less, more preferably 8 or more and 100 or less.

  The ratio between the hydroxyl value of the (meth) acrylic polymer and the hydroxyl value of the terpene phenolic tackifier in the pressure-sensitive adhesive composition can be determined by the following calculation formula.

  The pressure-sensitive adhesive composition of the present invention includes a structural unit derived from a monomer having a hydroxyl group, a hydroxyl value of 70 mgKOH / g or more, and a weight-average molecular weight of 1000 or more and 30000 or less (meth) acrylic oligomer (hereinafter, The ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass or more. The content of the terpene phenolic tackifier is 40% by mass or less, and the content of the terpene phenolic tackifier is 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer. And the total hydroxyl value calculated by the above formula (1) is The sum of the hydroxyl value calculated by the equation (2), the sum of hydroxyl value calculated by the equation (2) below is preferably at most 15 mgKOH / g or more 85 mgKOH / g.

In the pressure-sensitive adhesive composition of the present invention, as the oligomer contained in the pressure-sensitive adhesive composition, a (meth) acrylic oligomer having a hydroxyl value of 70 mgKOH / g or more and a large number of crosslinking points is used, compared to the case where no oligomer is used. , The crosslinked body becomes hard. For this reason, compared with the case where an oligomer is not used, excessive wetting and spreading to the adherend due to heating is suppressed, and more excellent high-speed peelability and lower peel dependency are exhibited.
In general, when the adhesive film is peeled from the adherend, the adherend may be contaminated, and the adherend may need to be discarded. Therefore, the adhesive film is required to have a low property of contaminating the adherend (hereinafter also referred to as “contamination”), that is, it is difficult to contaminate the adherend. Furthermore, the pressure-sensitive adhesive composition containing an oligomer tends to contaminate the adherend because the oligomer tends to remain on the surface of the adherend upon peeling. In particular, when the adhesive force of the pressure-sensitive adhesive layer is increased by the heat treatment and is difficult to peel, the surface of the adherend is more easily contaminated.
On the other hand, in the pressure-sensitive adhesive composition of the present invention, there are many crosslinking points of the oligomer contained in the pressure-sensitive adhesive composition, and since there are few uncrosslinked oligomers, it is difficult to contaminate the adherend and exhibits low contamination. .

  In the present specification, the “hydroxy value of (meth) acrylic oligomer” is determined by the following calculation formula. In the following calculation formula, 56.1 is the molecular weight of KOH.

  When there are two or more monomers having a hydroxyl group used in the (meth) acrylic oligomer, the hydroxyl value is obtained according to the above formula for each monomer, and the obtained values are summed to obtain the hydroxyl value. Ask.

  When the pressure-sensitive adhesive composition of the present invention further contains a specific (meth) acrylic oligomer, the total hydroxyl value calculated by the above formula (2) in the pressure-sensitive adhesive composition is more high-speed peelability after heat treatment. From the viewpoint of improving and imparting sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend, it is preferably 15 mgKOH / g or more and 85 mgKOH / g or less, more preferably 15 mgKOH / g or more and 75 mgKOH / g or less. preferable.

  When the pressure-sensitive adhesive composition of the present invention further contains a specific (meth) acrylic oligomer, the total hydroxyl value of the (meth) acrylic polymer and acrylic oligomer in the pressure-sensitive adhesive composition (that is, the hydroxyl value of the acrylic resin), The ratio of the hydroxyl value of the terpene phenolic tackifier (hydroxyl value of the acrylic resin / hydroxyl value of the terpene phenolic tackifier) is improved from the viewpoint of further improving the high-speed release property and lowering the release rate dependency. 5 or more and 500 or less are preferable, and 8 or more and 100 or less are more preferable.

  The ratio between the hydroxyl value of the acrylic resin and the hydroxyl value of the terpene phenolic tackifier in the pressure-sensitive adhesive composition is determined by the following calculation formula.

  Hereinafter, each component of the pressure-sensitive adhesive composition of the present invention will be described.

<(Meth) acrylic polymer>
The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention contains a structural unit derived from a monomer having a hydroxyl group, has a hydroxyl value of 10 mgKOH / g or more, and a weight average molecular weight of 300000 or more and 1800000 or less. .

A (meth) acrylic polymer is crosslinked by an isocyanate compound by including a structural unit derived from a monomer having a hydroxyl group.
Moreover, it is excellent in the high-speed peelability after heat processing because the hydroxyl value of a (meth) acrylic-type polymer is 10 mgKOH / g or more.
Furthermore, the weight average molecular weight of the (meth) acrylic polymer is 300,000 or more, and it is easy to adjust the viscoelasticity of the pressure-sensitive adhesive layer. The period of time that can be stored after mixing (hereinafter also referred to as “pot life”) is long, and it is easy to produce an adhesive film.
The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention may be only one type, or two or more types having different monomer compositions, weight average molecular weights, and the like.

  In the present specification, the “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 kind of monomer having a hydroxyl group is not particularly limited.
Examples of the monomer having a hydroxyl group include an alkyl (meth) acrylate having a hydroxyl group as a substituent and a polyalkylene glycol (meth) acrylate having a hydroxyl group.

  The alkyl part of the alkyl (meth) acrylate having a hydroxyl group as a substituent may be linear, branched or cyclic. The number of carbon atoms in the alkyl moiety of the alkyl (meth) acrylate having a hydroxyl group as a substituent is preferably in the range of 1-12. When the carbon number of the alkyl moiety is within the above range, the adhesiveness and the adhesiveness with the substrate when used as an adhesive film are excellent. For the same reason, the number of carbon atoms in the alkyl moiety of the alkyl (meth) acrylate having a hydroxyl group as a substituent is more preferably in the range of 2-6, and still more preferably in the range of 2-4.

  Examples of the alkylene glycol constituting the polyalkylene glycol moiety of the polyalkylene glycol (meth) acrylate having a hydroxyl group include ethylene glycol, propylene glycol, and a combination of ethylene glycol and propylene glycol.

  Specific examples of the monomer having a hydroxyl group include 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 (meta ) Acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, glycerin mono (Me ) Acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, and poly (ethylene glycol - include propylene glycol) mono (meth) acrylate. Monomers having a hydroxyl group may be used alone or in combination of two or more.

  The monomer having a hydroxyl group has an appropriate pressure-sensitive adhesive force on the adherend and an excellent high-speed peelability, and from the viewpoint of lowering the dependency on the peel rate, an alkyl (meth) acrylate having a hydroxyl group as a substituent. And is preferably composed of 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate. More preferably, at least one selected from the group is included, and at least one selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 6-hydroxyhexyl (meth) acrylate. Further including species Masui.

  The alkyl (meth) acrylate having a hydroxyl group as a substituent particularly preferably includes at least one selected from 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. These monomers have particularly good compatibility and copolymerization with other monomers and also have good reactivity with isocyanate compounds.

  Furthermore, the (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention preferably contains a structural unit derived from alkyl (meth) acrylate. Adhesive force can be easily adjusted because a (meth) acrylic-type polymer contains the structural unit derived from an alkyl (meth) acrylate.

  In the present specification, the “structural unit derived from alkyl (meth) acrylate” means a structural unit formed by addition polymerization of alkyl (meth) acrylate.

  When the (meth) acrylic polymer includes a structural unit derived from alkyl (meth) acrylate, the alkyl (meth) acrylate constituting the structural unit derived from alkyl (meth) acrylate is an unsubstituted alkyl (meth) acrylate. Preferably, the type is not particularly limited. The alkyl group of the alkyl (meth) acrylate may be linear, branched or cyclic. Moreover, the range of 1-18 is preferable and, as for carbon number of an alkyl group, the range of 1-12 is more preferable. When the carbon number of the alkyl group is within the above range, the adhesiveness and the adhesiveness to the substrate when used as an adhesive film are excellent.

Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, s-butyl (meth) acrylate, t -Butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (meth) acrylate, n-decyl (Meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
Alkyl (meth) acrylate may be used individually by 1 type, and may use 2 or more types together.

  Alkyl (meth) acrylate is 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate, i-nonyl acrylate, and lauryl from the viewpoint of compatibility between (meth) acrylic polymer and terpene phenolic tackifier. It is preferable to include at least one selected from the group consisting of methacrylates.

The ratio of the structural unit derived from the alkyl (meth) acrylate in the total structural unit of the (meth) acrylic polymer is excellent while providing the adhesive layer with sufficient adhesive strength so as not to easily fall off from the adherend. From the viewpoint of maintaining high-speed peelability, the content is preferably 50% by mass or more, more preferably 65% by mass or more, and still more preferably 80% by mass or more based on the entire structural unit.
In addition, the proportion of the structural unit derived from alkyl (meth) acrylate in the total structural units of the (meth) acrylic polymer is preferably 97% by mass or less based on the total structural units from the viewpoint of keeping contamination low. 96 mass% or less is more preferable, and 95 mass% or less is still more preferable.

The (meth) acrylic polymer preferably contains 50% by mass or more of a structural unit derived from a monomer having an acryloyl group with respect to all structural units (hereinafter also referred to as “acrylic monomer”). The (meth) acrylic polymer contains 50% by mass or more of structural units derived from acrylic monomers with respect to all the structural units, so that the copolymerizability is improved and the hydroxyl groups are more uniformly distributed in the (meth) acrylic polymer Therefore, unevenness in cross-linking is further suppressed, and the contamination property can be further suppressed.
From the same viewpoint, the (meth) acrylic polymer preferably contains 60% by mass or more, more preferably 80% by mass or more, of structural units derived from acrylic monomers with respect to all the structural units.

  Within the range in which the effects of the present invention are exhibited, the (meth) acrylic polymer has a constitutional unit other than a constitutional unit derived from a monomer having a hydroxyl group and an alkyl (meth) acrylate that is an arbitrary constitutional unit. Units (hereinafter also referred to as “other structural units”) may be included. In this case, the total ratio of the structural unit derived from the monomer having a hydroxyl group and the structural unit derived from the alkyl (meth) acrylate is preferably 70% by mass or more based on the total structural unit of the (meth) acrylic polymer. 75 mass% or more is more preferable, and 80 mass% or more is still more preferable.

The type of monomer constituting other structural units is not particularly limited.
Specific examples of monomers constituting other structural units include (meth) acrylates having a cyclic group represented by benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, and ethoxy. Alkoxyalkyl (meth) acrylates represented by ethyl (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and aromatic monovinyl, acrylonitrile represented by vinyltoluene and Examples thereof include vinyl cyanide represented by methacrylonitrile, vinyl formate, vinyl acetate, vinyl propionate, vinyl esters represented by vinyl versatate, and various derivatives of these monomers. Moreover, the monomer which has functional groups other than a hydroxyl group, such as a carboxy group, a glycidyl group, an amide group or an N-substituted amide group, and a tertiary amino group, is mentioned.

  Specific examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, 2- (meth) acryloyloxyethyl succinate. Acid, monohydroxyethyl maleate (meth) acrylate, monohydroxyethyl fumarate (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) Acrylic acid dimer and ω-carboxy-polycaprolactone mono (meth) acrylate.

  Specific examples of the monomer having a glycidyl group include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meth) allyl ether, and 3,4-epoxycyclohexyl (meth) allyl ether is mentioned.

  Specific examples of the monomer having an amide group or an N-substituted amide group include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N -Ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-tert-butylacrylamide, N-octylacrylamide, and diacetone acrylamide.

  Specific examples of the monomer having a tertiary amino group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropyl (meth) acrylamide.

The hydroxyl value of the (meth) acrylic polymer is preferably 12 mgKOH / g or more, more preferably 14 mgKOH / g or more, and still more preferably 16 mgKOH / g or more from the viewpoint of further improving the high-speed peelability.
In addition, the hydroxyl value of the (meth) acrylic polymer is 75 mgKOH / g from the viewpoint of maintaining excellent high-speed peelability while imparting sufficient pressure-sensitive adhesive strength to the pressure-sensitive adhesive layer so as not to easily fall off from the adherend. The following is preferable, 70 mgKOH / g or less is more preferable, and 65 mgKOH / g or less is still more preferable.

  The weight average molecular weight of the (meth) acrylic polymer is preferably 400,000 or more, more preferably 500,000 or more, from the viewpoint of keeping the contamination property low. In addition, the weight average molecular weight of the (meth) acrylic polymer is preferably 1400000 or less, and more preferably 1000000 or less, from the viewpoint of increasing the pot life.

  The dispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth) acrylic polymer is not particularly limited. For example, the dispersity (Mw / Mn) of the (meth) acrylic polymer is preferably in the range of 1 to 30 from the viewpoint of keeping the contamination property low.

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

~conditions~
Measuring device: High-speed GPC (model number: HLC-8220 GPC, manufactured by Tosoh Corporation)
Detector: differential refractometer (RI) (built in HLC-8220, manufactured by Tosoh Corporation)
Column: 4 TSK-GEL GMHXL (manufactured by Tosoh Corporation) connected in series Column temperature: 40 ° C
Eluent: Tetrahydrofuran Sample concentration: 0.2% by mass
Injection volume: 100 μL
Flow rate: 0.6 mL / min

  The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably −50 ° C. or lower. When the Tg of the (meth) acrylic polymer is −50 ° C. or lower, the elasticity of the (meth) acrylic polymer is sufficiently low, so that an increase in adhesive force due to heat treatment can be suppressed, and high-speed peelability is more excellent. Further, when the Tg of the (meth) acrylic polymer is −50 ° C. or lower, the compatibility between the (meth) acrylic polymer and the terpene phenolic tackifier becomes high, so that the cross-linking structure with the tackifier becomes more uniform. It is formed. Thereby, the raise of the adhesive force by heat processing can be suppressed, and high-speed peelability is more excellent.

The Tg of the (meth) acrylic polymer is −50 by using a monomer having a Tg of −50 ° C. or less as a homopolymer as all or part of the monomer constituting the (meth) acrylic polymer. It can be adjusted to below ℃.
Specific examples of monomers having a Tg of −50 ° C. or less when homopolymers are butyl acrylate (−57 ° C.), 2-ethylhexyl acrylate (−76 ° C.), lauryl methacrylate (−65 ° C.), octyl Examples include acrylate (−65 ° C.), isooctyl acrylate (−58 ° C.), isononyl acrylate (−58 ° C.), and isomyristyl acrylate (−56 ° C.).

  Specific examples of monomers having a Tg exceeding −50 ° C. when homopolymers are methyl acrylate (5 ° C.), 4-hydroxybutyl acrylate (−39 ° C.), 2-hydroxyethyl acrylate (−15 ° C.), And acrylic acid (166 ° C.).

  “Tg when homopolymer” refers to Tg of a homopolymer produced by polymerizing the monomer alone. The Tg of the homopolymer was measured using a differential scanning calorimeter (DSC) (model number: EXSTAR6000, manufactured by Seiko Instruments Inc.) in a nitrogen stream, 10 mg of a measurement sample, and a heating rate of 10 ° C./min. The inflection point of the DSC curve obtained by measurement under the conditions is the Tg of the homopolymer.

  Tg of the (meth) acrylic polymer is a value obtained by converting the absolute temperature (K) obtained by calculation from the following formula into Celsius temperature (° C.).

In the formula, Tg1, Tg2,..., Tg (k-1), Tgk are glasses represented by absolute temperature (K) when each monomer constituting the (meth) acrylic polymer is a homopolymer. Represents the transition temperature. w1, w2,..., w (k-1), wk each represents a mass fraction of each monomer constituting the (meth) acrylic polymer, and w1 + w2 + ... + w (k-1) + wk = 1. It is.
The absolute temperature (K) can be converted to Celsius temperature (° C) by subtracting 273 from the absolute temperature (K), and the Celsius temperature (° C) can be converted to absolute temperature (K) by adding 273 to the Celsius temperature (° C). Can be converted to

<(Meth) acrylic oligomer>
The pressure-sensitive adhesive composition of the present invention includes a structural unit derived from a monomer having a hydroxyl group, and further includes a (meth) acrylic oligomer having a hydroxyl value of 70 mgKOH / g or more and a weight average molecular weight of 1,000 to 30,000. It is preferable.
When the pressure-sensitive adhesive composition of the present invention further contains a (meth) acrylic oligomer that satisfies the above requirements, an increase in pressure-sensitive adhesive force due to heat treatment can be further suppressed.

  When the pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic oligomer, the (meth) acrylic oligomer may be only one kind, and two or more kinds having different monomer compositions, weight average molecular weights, and the like. There may be.

The structural unit derived from the monomer having a hydroxyl group contained in the (meth) acrylic oligomer contributes to an improvement in high-speed peelability, a reduction in peel rate dependency, and a reduction in contamination.
The kind of monomer having a hydroxyl group is not particularly limited.
As a monomer which has a hydroxyl group, the monomer which has a hydroxyl group in the above-mentioned (meth) acrylic-type polymer can be mentioned, A preferable example is also the same.

The (meth) acrylic oligomer preferably includes a structural unit derived from an alkyl (meth) acrylate. The structural unit derived from alkyl (meth) acrylate contributes to the adjustment of adhesive force.
Examples of the alkyl (meth) acrylate constituting the structural unit derived from the alkyl (meth) acrylate include alkyl (meth) acrylates in the aforementioned (meth) acrylic polymers, and preferred examples are also the same.

  The proportion of the structural unit derived from alkyl (meth) acrylate in the total structural unit of the (meth) acrylic oligomer is excellent while giving the adhesive layer sufficient adhesive strength so that it does not easily fall off from the adherend. From the viewpoint of maintaining high-speed peelability, the content is preferably 40% by mass or more, more preferably 45% by mass or more, and still more preferably 50% by mass or more based on all the structural units. The proportion of the structural unit derived from the alkyl (meth) acrylate in the total structural units of the (meth) acrylic oligomer is preferably 95% by mass or less, based on the total structural units, from the viewpoint of lowering contamination. % Or less is more preferable, and 85% by mass or less is still more preferable.

The (meth) acrylic oligomer preferably contains 50% by mass or more of a structural unit derived from a monomer having an acryloyl group (acrylic monomer) with respect to all the structural units. By including 50% by mass or more of structural units derived from acrylic monomers with respect to all the structural units, the copolymerizability is improved and the hydroxyl groups can be more evenly distributed in the (meth) acrylic oligomer. It is suppressed more and pollution property can be suppressed lower.
The (meth) acrylic oligomer preferably contains 60% by mass or more, more preferably 70% by mass or more, of structural units derived from acrylic monomers with respect to all the structural units.

The (meth) acrylic oligomer is a constitutional unit other than a constitutional unit derived from a monomer having a hydroxyl group and an alkyl (meth) acrylate that is an arbitrary constitutional unit within the range in which the effect of the present invention is exhibited. Units (other structural units) may be included. In this case, the total ratio of the structural unit derived from the monomer having a hydroxyl group in the total structural units of the (meth) acrylic oligomer and the structural unit derived from the alkyl (meth) acrylate is 50 with respect to the total structural units. It is preferably at least mass%, more preferably at least 60 mass%, still more preferably at least 70 mass%.
Examples of the monomer constituting other structural units include monomers constituting other structural units in the aforementioned (meth) acrylic polymers.

The hydroxyl value of the (meth) acrylic oligomer is sufficiently cross-linked with the (meth) acrylic polymer from the viewpoint of further improving the high-speed peelability, lowering the release rate dependency, and lowering the contamination property. 70 mgKOH / g or more is preferable, 85 mgKOH / g or more is more preferable, and 95 mgKOH / g or more is still more preferable.
In addition, the hydroxyl value of the (meth) acrylic oligomer provides the adhesive layer with sufficient adhesive strength that does not easily fall off from the adherend, while maintaining excellent high-speed peelability, and the adhesive layer From the viewpoint of reducing the haze, 200 mgKOH / g or less is preferable, 180 mgKOH / g or less is more preferable, and 160 mgKOH / g or less is more preferable.

  The weight average molecular weight of the (meth) acrylic oligomer is preferably 1000 or more, more preferably 4000 or more, and still more preferably 7000 or more, from the viewpoint of suppressing contamination. From the viewpoint of reducing the haze of the pressure-sensitive adhesive layer, the weight average molecular weight of the (meth) acrylic oligomer is preferably 30000 or less, more preferably 25000 or less, and still more preferably 20000 or less.

  The dispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth) acrylic oligomer is not particularly limited. For example, from the viewpoint of imparting sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend, while maintaining excellent high-speed peelability and keeping contamination low, (meth) acrylic The degree of oligomer dispersion (Mw / Mn) is preferably in the range of 1-30.

  The weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth) acrylic oligomer are the same as the method for measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth) acrylic polymer described above. Measured.

  The glass transition temperature (Tg) of the (meth) acrylic oligomer is preferably −20 ° C. or lower. When the Tg of the (meth) acrylic oligomer is −20 ° C. or lower, an increase in adhesive force due to heat treatment can be suppressed, and thus high-speed peelability is more excellent.

  The glass transition temperature (Tg) of the (meth) acrylic oligomer is calculated in the same manner as the calculation method of the glass transition temperature of the (meth) acrylic polymer described above.

The (meth) acrylic oligomer is 50 masses of structural units derived from monomers having a glass transition temperature (Tg) of −50 ° C. or lower when a homopolymer is used, with respect to all structural units of the (meth) acrylic oligomer. % Or more is preferable. For example, it is preferable to contain 50% by mass or more of 2-ethylhexyl acrylate having a Tg of −76 ° C. as a homopolymer with respect to all structural units of the (meth) acrylic oligomer. In this case, since the glass transition temperature of the (meth) acrylic oligomer is sufficiently low and the pressure-sensitive adhesive layer is more easily adapted to the adherend, the pressure-sensitive adhesive film is difficult to fall off during processing of the adherend.
Examples of the monomer having a Tg of −50 ° C. or less when the homopolymer is used include monomers having a Tg of −50 ° C. or less when the homopolymer in the (meth) acrylic polymer described above is used.

When the pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic oligomer, the ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass to 40 mass% is preferable, 3 mass%-30 mass% is more preferable, 3 mass%-20 mass% is still more preferable.
When the proportion of the (meth) acrylic oligomer is 1% by mass or more, the effect of adding the (meth) acrylic oligomer is sufficiently obtained. Since the raise of the adhesive force by heat processing can be suppressed as the ratio of a (meth) acrylic-type oligomer is 40 mass% or less, high-speed peelability is more excellent. In addition, since the (meth) acrylic polymer and the (meth) acrylic oligomer are sufficiently cross-linked, the (meth) acrylic oligomer hardly remains on the adherend, and the contamination property can be further reduced.

<Isocyanate compound>
The pressure-sensitive adhesive composition of the present invention contains an isocyanate compound.
The isocyanate compound functions as a crosslinking agent.
Examples of the isocyanate compound include xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, aromatic polyisocyanate compounds represented by tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenation of the above-described aromatic polyisocyanate compound. Chain or cyclic aliphatic polyisocyanate compounds typified by products, biuret, dimer, trimer or pentamer of these polyisocyanate compounds, these polyisocyanate compounds and polyols such as trimethylolpropane Examples include adducts with compounds. These isocyanate compounds may be used individually by 1 type, and may use 2 or more types together.

When the pressure-sensitive adhesive composition of the present invention is used for applications in which transparency is important, the isocyanate compound is a chain or cyclic aliphatic polyisocyanate compound and a biuret of a chain or cyclic aliphatic polyisocyanate compound. An isocyanate compound having an isocyanurate structure, which is a trimer of hexamethylene diisocyanate, and an adduct of hexamethylene diisocyanate, preferably at least one selected from the group consisting of a dimer, a trimer, a pentamer and an adduct And at least one selected from the group consisting of biurets of hexamethylene diisocyanate is more preferred. Since these isocyanate compounds do not have a structure derived from an aromatic ring, the pressure-sensitive adhesive layer after the heat treatment is hardly yellowed, and a pressure-sensitive adhesive film that is superior in transparency can be obtained.
Examples of uses that place importance on transparency include surface protection film uses for optical members.

  A commercially available product can be used as the isocyanate compound. Examples of commercially available products include “Coronate HX”, “Coronate HL-S”, “Coronate L”, “Coronate 2031”, “Coronate 2030”, “Coronate 2234”, and “Coronate 2785” manufactured by Nippon Polyurethane Co., Ltd. , “Aquanate 200” and “Aquanate 210”, “Sumijour N3300”, “Death Module N3400”, and “Sumijoule N-75” manufactured by Sumika Bayer Urethane Co., Ltd., manufactured by Asahi Kasei Corporation "Duranate E-405-80T", "Duranate 24A-100", and "Duranate TSE-100" as well as "Takenate D-110N", "Takenate D-120N", "Mitsui Takeda Chemical Co., Ltd." Takenate M-631N ”and“ MT-Olestar NP1200 ” It can be suitably used those commercially available Ri.

The content of the isocyanate compound is, for example, a hydroxyl group contained in the (meth) acrylic polymer [when the pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic oligomer described above, the (meth) acrylic polymer The total number of hydroxyl groups contained and the hydroxyl groups contained in the (meth) acrylic oligomer] is defined as 1 equivalent, and the isocyanate group is 0.5 equivalents or more and 2.0 equivalents per 1 equivalent of this hydroxyl group (or the total hydroxyl groups). An amount that is equal to or less than the equivalent is preferred.
When the equivalent of the isocyanate group is 0.5 equivalent or more with respect to 1 equivalent of the hydroxyl group (or the total number of hydroxyl groups), the pressure-sensitive adhesive layer becomes sufficiently hard, and an increase in adhesive force due to heat treatment can be suppressed, so that high-speed peeling More excellent. Moreover, since the quantity of the (meth) acrylic oligomer which is not cross-linked can be kept low, the contamination can be kept lower. When the equivalent of the isocyanate group is 2.0 equivalents or less with respect to 1 equivalent of the hydroxyl group (or the total number of hydroxyl groups), the amount of the isocyanate compound that has not reacted with the (meth) acrylic polymer can be kept low. Can be kept lower.
The content of the isocyanate compound is a hydroxyl group contained in the (meth) acrylic polymer [when the pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic oligomer described above, it is contained in the (meth) acrylic polymer. Total of hydroxyl group and hydroxyl group contained in (meth) acrylic oligomer] The amount by which the isocyanate group is 0.55 equivalents or more and 1.6 equivalents or less is more preferable with respect to 1 equivalent, 0.6 equivalents or more and 1.2 equivalents More preferred are the following amounts.

<Terpene phenol tackifier>
The pressure-sensitive adhesive composition of the present invention contains a terpene phenolic tackifier.
A terpene phenol type tackifier may be used individually by 1 type, and may use 2 or more types together.

  In the present specification, “terpene phenolic tackifier” means a copolymer of terpenes and a phenol compound.

  Examples of the terpene phenolic tackifier include monocyclic monoterpenes represented by α-pinene, β-pinene, and dipentene (limonene), and phenolic compounds represented by phenol, cresol, and bisphenol A. A copolymer is mentioned.

  The terpene phenol type tackifier can use a commercial item. Examples of commercially available products include “YS Polystar U115”, “YS Polystar U130”, “YS Polystar T80”, “YS Polystar T100”, “YS Polystar T115”, “YS Polystar T130”, “YS Polystar T130”, “YS Polystar T130”, “YS Polyster TH130”, “YS Polystar T145”, “YS Polystar T160”, “YS Polystar S145”, “YS Polystar G125”, “YS Polystar G150”, “YS Polystar N125”, “YS Polystar K125”, and “YS Polystar K140 "and those commercially available under the trade names" Tamanol 803L "and" Tamanol 901 "manufactured by Arakawa Chemical Industries, Ltd. can be preferably used.

The hydroxyl value of the terpene phenol tackifier is preferably 20 mgKOH / g or more and 160 mgKOH / g or less.
When the hydroxyl value of the terpene phenolic tackifier is within the above range, the crosslinking points are sufficiently large, and compatibility with (meth) acrylic polymers and (meth) acrylic oligomers (that is, acrylic resins) is achieved. Since it is excellent, the terpene phenolic tackifier is sufficiently and uniformly crosslinked with the acrylic resin through the isocyanate compound. Thereby, since the raise of the adhesive force by heat processing can be suppressed, the high-speed peelability after heat processing is more excellent, and the peeling rate dependence can be suppressed lower.

The content of the terpene phenol tackifier is a (meth) acrylic polymer [when the pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic oligomer described above, the (meth) acrylic polymer and (meth) Total with acrylic oligomer] is 0.1 to 5 parts by mass with respect to 100 parts by mass.
When the content of the terpene phenol tackifier is 0.1 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer (or the total of the acrylic polymer and the (meth) acrylic oligomer), the terpene phenolic The effect of adding tackifier is sufficiently obtained. When the content of the terpene phenolic tackifier is 5 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (or the total of the acrylic polymer and the (meth) acrylic oligomer), the original properties of the tackifier The effect of imparting adhesive strength, which is one of the above, is small, and an increase in adhesive strength due to heat treatment can be sufficiently suppressed, so that high-speed peelability is more excellent.
Further, from the same viewpoint, the content of the terpene phenol-based tackifier is preferably 0.3 parts by mass or more and 4 parts by mass or less, and more preferably 0.5 parts by mass or more and 3 parts by mass or less.

<Other ingredients>
Examples of other components that the pressure-sensitive adhesive composition of the present invention may contain in addition to the (meth) acrylic polymer, isocyanate compound, terpene phenolic tackifier, and optional (meth) acrylic oligomer include cross-linking Catalyst, chelating agent, solvent, weathering stabilizer, plasticizer, softener, dye, pigment, inorganic filler, antioxidant, polymer other than (meth) acrylic polymer, and oligomer other than (meth) acrylic oligomer Is mentioned.
When the pressure-sensitive adhesive composition contains these other components, the content of the other components can be appropriately set within the range in which the effect of the present invention is exhibited.

Examples of the crosslinking catalyst include organic tin compounds typified by dibutyltin dilaurate and dioctyltin dilaurate, and organic zirconium compounds typified by zirconium tetraacetylacetonate and zirconium dibutoxybis (ethylacetoacetate). .
When the pressure-sensitive adhesive composition contains these crosslinking catalysts, the initial curing rate can be increased. Among these, as the crosslinking catalyst, an organotin compound is preferable because it is easy to adjust the adhesive force and the crosslinking reaction rate to appropriate ranges.

When the pressure-sensitive adhesive composition contains a cross-linking catalyst, the pot life tends to be shortened, and therefore it is preferable to further contain a chelating agent. When the pressure-sensitive adhesive composition contains a chelating agent, the pot life tends to be long.
Examples of the chelating agent include β-diketones and β-ketoesters. Examples of β-diketones or β-ketoesters include acetylacetone, methyl acetoacetate, ethyl acetoacetate, acetoacetate-n-propyl, and isopropyl acetoacetate. A pot life becomes long because an adhesive composition contains these chelating agents. Among these, as the chelating agent, acetylacetone is preferable from the viewpoint of extending the pot life.

  As a combination of a crosslinking catalyst and a chelating agent, a combination of an organic tin compound and acetylacetone is preferable from the viewpoint of increasing adhesive strength and pot life.

<Method for producing (meth) acrylic polymer and (meth) acrylic oligomer>
The production method of the (meth) acrylic polymer and (meth) acrylic oligomer used in the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, it can be produced by polymerizing monomers by a known polymerization method represented by solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, as the polymerization method, solution polymerization is preferable because the treatment process is relatively simple and can be performed in a short time.

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

  Examples of the organic solvent used in the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha. Aliphatic or alicyclic typified by aromatic hydrocarbons, n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and turpentine oil Hydrocarbons, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, esters represented by methyl benzoate, acetone, methyl ethyl ketone, Methyl-i-butyl ketone, isophorone, cyclohexanone, and methylcyclohex Ketones represented by non, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and glycol ethers represented by diethylene glycol monobutyl ether, and methyl alcohol, Examples include alcohols represented by ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t-butyl alcohol. These organic solvents may be used individually by 1 type, and may use 2 or more types together.

  In the production of the (meth) acrylic polymer and the (meth) acrylic oligomer, it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction of esters and ketones. In particular, from the viewpoint of the solubility of the (meth) acrylic polymer and the (meth) acrylic oligomer, the ease of the polymerization reaction, etc., the organic solvent is at least one selected from the group consisting of ethyl acetate, methyl ethyl ketone, and acetone. Species are preferred.

As the polymerization initiator, organic peroxides, azo compounds and the like used in usual solution polymerization can be used.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxide. Carbonato, t-butylperoxybivalate, 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- octyl peroxy cyclohexyl), and butane.
Examples of the azo compound include 2,2′-azobis-i-butylnitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-4-methoxy-2,4-dimethyl. Examples include valeronitrile, 1,1′-azobis-cyclohexane-1-carbonitrile, and 2,2′-azobis (methyl isobutyrate).

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

The amount of the polymerization initiator used in the production of the (meth) acrylic polymer ranges from 0.01 parts by mass to 2 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic polymer. Is preferable, and the range of 0.1 parts by mass or more and 1 part by mass or less is more preferable.
In the production of the (meth) acrylic oligomer, the range of 0.1 to 20 parts by mass is preferable with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic oligomer, and 1 to 10 parts by mass. A range of less than or equal to part by mass is more preferred.

In the production of the (meth) acrylic polymer and the (meth) acrylic oligomer, a chain transfer agent can be used as necessary as long as the purpose and effect of the present invention are not impaired.
Examples of the chain transfer agent include cyanoacetic acid, cyanoacetic acid alkyl esters having 1 to 8 carbon atoms, bromoacetic acid, bromoacetic acid alkyl esters having 1 to 8 carbon atoms, α-methylstyrene, anthracene, phenanthrene, fluorene. And aromatic compounds typified by 9-phenylfluorene, aromatic nitro compounds typified by p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and p-nitrotoluene, Benzoquinone derivatives represented by benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives represented by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2- Tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloro Halogenated hydrocarbons typified by tan, tribromomethane, and 3-chloro-1-propene, aldehydes typified by chloral and furaldehyde, alkyl mercaptans having 1 to 18 carbon atoms, thiophenol and toluene mercaptan Specific examples include aromatic mercaptans, mercaptoacetic acid, alkyl esters having 1 to 10 carbon atoms of mercaptoacetic acid, hydroxyalkyl mercaptans having 1 to 12 carbon atoms, and terpenes represented by binene and terpinolene.

  The amount of the chain transfer agent used is, for example, in the range of 0.005 to 10.0 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic polymer and (meth) acrylic oligomer. Can be.

  As a polymerization temperature in producing a (meth) acrylic polymer and a (meth) acrylic oligomer, a range of 30 ° C. to 180 ° C. is preferable, a range of 50 ° C. to 150 ° C. is more preferable, and a temperature of 50 ° C. to 100 ° C. A range is still more preferable, and a range of 60 ° C to 90 ° C is particularly preferable.

<Adhesive film>
The pressure-sensitive adhesive film of the present invention includes a base material and a pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition of the present invention. That is, in the pressure-sensitive adhesive film of the present invention, a base material and a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention are laminated. The pressure-sensitive adhesive film of the present invention has a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention, so that the high-speed peelability after the heat treatment is excellent and the peel speed dependency is lowered.

  The material of the base material constituting the pressure-sensitive adhesive film of the present invention is not particularly limited. As a material of the base material, from the viewpoint of inspection and management of optical members by fluoroscopy, for example, polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, etc. Resin and acrylic resin are mentioned. Among these, as the base material, a polyester-based resin is preferable from the viewpoint of surface protection performance, and a polyethylene terephthalate resin is more preferable from the viewpoint of transparency and heat resistance.

  The thickness in particular of a base material is not restrict | limited, For example, it is 500 micrometers or less, the range of 5 micrometers-300 micrometers is preferable, and the range of 10 micrometers-200 micrometers is more preferable.

  The method for forming the pressure-sensitive adhesive layer provided on the substrate is not particularly limited, and a commonly used method can be adopted. Formation of the pressure-sensitive adhesive layer on the substrate is performed, for example, directly on the substrate that is the base film, with the pressure-sensitive adhesive composition of the present invention as it is or diluted with a solvent as necessary. It can be performed by a method of applying, drying and removing the solvent, curing and terminating the crosslinking reaction. As another method for forming the pressure-sensitive adhesive layer on the substrate, for example, the pressure-sensitive adhesive composition of the present invention is applied on a release sheet such as paper or polyester film that has been subjected to a release treatment with a silicone resin or the like. And drying to remove the solvent, curing and terminating the cross-linking reaction to form a pressure-sensitive adhesive layer, and then pressing the surface of the release sheet on which the pressure-sensitive adhesive layer is formed is brought into contact with the substrate and pressurized. A method of transferring the pressure-sensitive adhesive layer to the substrate side can be mentioned. If necessary, a release film may be laminated on the surface of the pressure-sensitive adhesive layer on the substrate thus prepared.

  Curing is performed, for example, in an environment of 23 ° C. and 50% RH for 1 to 10 days. By curing, the crosslinking reaction of the pressure-sensitive adhesive composition is completed, and a pressure-sensitive adhesive layer is formed.

  The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the type of adherend and the surface roughness of the adherend. Generally, the thickness of the pressure-sensitive adhesive layer is in the range of 1 μm to 100 μm, preferably in the range of 5 μm to 50 μm, and more preferably in the range of 15 μm to 30 μm.

  The pressure-sensitive adhesive film of the present invention has a sufficient pressure-sensitive adhesive strength so that the pressure-sensitive adhesive layer does not easily fall off from the adherend even after heat treatment (that is, a sufficiently large peel strength when peeling at low speed). It is preferable that the film can be easily peeled when peeled at a high speed (that is, a large peeling force is not needed when peeled at a high speed).

From such a viewpoint, the pressure-sensitive adhesive film of the present invention peels off the pressure-sensitive adhesive force (peeling force) to the adherend of the pressure-sensitive adhesive layer in a 180-degree peel test at 23 ° C. after heat treatment at 150 ° C. for 1 hour. At a speed of 10 m / min (high speed peeling), it is preferably 0.45 N / 25 mm or less, more preferably 0.4 N / 25 mm or less, and still more preferably 0.35 N / 25 mm or less.
The pressure-sensitive adhesive film can be easily peeled from the adherend when the pressure-sensitive adhesive force (peeling force) is 0.45 N / 25 mm or less during high-speed peeling. In particular, the peelability at a wide width is good.

  From the viewpoint of preventing damage to the adherend due to the adhesive film becoming difficult to peel off from the adherend due to heat treatment, the pressure-sensitive adhesive film of the present invention hardly changes the peel force even if the peel speed changes (that is, the peel speed). Preferably, the dependency is low.

From such a viewpoint, the pressure-sensitive adhesive film of the present invention preferably has a peel rate dependency rate (unit:%) of the pressure-sensitive adhesive layer in a 180-degree peel test at 23 ° C. after heat treatment at 150 ° C. for 1 hour. It is 300% or less, more preferably 270% or less, and still more preferably 200% or less.
When the peeling rate dependency rate is 300% or less, the pressure-sensitive adhesive film can be easily peeled from the adherend without depending on the peeling rate.
In this specification, the “peeling rate dependency rate” means a peeling rate of 10 m / min (high speed peeling) with respect to an adhesive force (hereinafter also referred to as “low speed peeling force”) at a peeling speed of 0.3 m / min (low speed peeling). It is a ratio of adhesive strength (hereinafter also referred to as “high-speed peeling force”), and is obtained by the following calculation formula.
Peeling speed dependency rate (%) = (high speed peeling force / low speed peeling force) × 100

  The gel fraction of the pressure-sensitive adhesive layer is preferably in the range of 90% by mass to 100% by mass, more preferably in the range of 93% by mass to 100% by mass, and 95% by mass to 100% by mass from the viewpoint of adhesive strength. The range of is more preferable.

In the present specification, the gel fraction of the pressure-sensitive adhesive layer is a ratio of a solvent-insoluble content measured using ethyl acetate as an extraction solvent. Specifically, the measurement is performed according to the following (1) to (4).
(1) About 0.25 g of the adhesive layer is affixed to a 250-mesh wire mesh (100 mm × 100 mm) whose mass has been accurately measured with a precision balance. Then, the wire mesh is folded five times to obtain a sample. Thereafter, the mass is accurately measured with a precision balance.
(2) The obtained sample is immersed in 80 ml of ethyl acetate for 3 days.
(3) A sample is taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. Thereafter, the mass is accurately measured with a precision balance.
(4) The gel fraction is calculated by the following formula.
Gel fraction (mass%) = (Z−X) / (Y−X) × 100
Where X is the mass (g) of the wire mesh, Y is the mass (g) before immersion of the wire mesh with the adhesive layer attached, and Z is the mass (g) of the wire mesh with the adhesive layer attached after drying. is there.

As an application of the pressure-sensitive adhesive film of the present invention, an application for attaching to an adherend to be heat-treated can be mentioned. Specifically, for example, it can be used as a surface protective film for an optical member, a surface protective film used in a manufacturing process of an electronic member, and a reinforcing film.
That is, the pressure-sensitive adhesive film of the present invention can be used as a heat-resistant pressure-sensitive adhesive film that protects or reinforces the surface of the adherend in the heat treatment step and can be easily peeled off after the heat treatment step.

The optical member as the adherend is, for example, a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a transparent conductive film (ITO film, ITO glass, etc.) ), And optical members used in liquid crystal display devices for design films and decorative films.
The optical member used for the liquid crystal display device may be heat-treated at, for example, 70 ° C. to 90 ° C. for the purpose of eliminating the disorder of the alignment of the liquid crystal when the liquid crystal display device is assembled.
A transparent conductive film, which is a kind of optical member used in a liquid crystal display device, is subjected to a heat treatment at, for example, 100 ° C. to 250 ° C. in a conductive substance crystallization step (ie, an annealing step). The surface to which the adhesive film of the transparent conductive film is attached may be the surface on which the transparent electrode is formed or the other surface.

Examples of the electronic member as the adherend include a flexible printed board and a rigid printed wiring board.
The flexible printed circuit board and the rigid printed circuit board are heat-treated at, for example, 100 ° C. to 250 ° C. in a hot press process.

The adherend to be heat-treated using the pressure-sensitive adhesive film of the present invention is preferably an adherend to be heat-treated at 100 to 250 ° C. The pressure-sensitive adhesive film of the present invention protects or reinforces the surface of an adherend in a heat treatment step at 100 ° C. to 250 ° C., and can be easily peeled off after the heat treatment step.
As an adherend heat-processed at 100 to 250 degreeC, a transparent conductive film, a flexible printed circuit board, and a rigid printed circuit board are mentioned, for example.

  The surface protective film is laminated on the surface of the optical member or the electronic member to protect the surface of the optical member or the electronic member from being contaminated or damaged. The optical member and the electronic member are subjected to heat treatment in the crystallization process (that is, the annealing process), the high temperature dry printing process, the etching process, the pressing process, etc. with the surface protective film being laminated on the optical member or the electronic member. Is done. Thereafter, at the stage where surface protection is no longer necessary, it is peeled off from the optical member or electronic member.

  The pressure-sensitive adhesive film of the present invention uses a hydroxyl group as a crosslinking point. Thereby, compared with the case where acidic groups, such as a carboxy group, are used as a cross-linking point, the metal is less likely to be oxidized.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

[Production of (meth) acrylic polymer]
[Production Example 1]
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a sequential dropping device, 25 parts by mass of ethyl acetate, 23.75 parts by mass of 2-ethylhexyl acrylate (2EHA) as an alkyl acrylate, and 4-as a monomer having a hydroxyl group 1.25 parts by mass of hydroxybutyl acrylate (4HBA) and 1,1′-azobiscyclohexane-1-carbonitrile (trade name: V-40, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator 0.0125 A mass part was added, and while stirring, the temperature in the reaction vessel was increased until reflux occurred. 10 minutes after the start of reflux, a solution prepared by dissolving 71.25 parts by mass of 2EHA, 3.75 parts by mass of 4HBA, 0.2 parts by mass of V-40, and 20.8 parts by mass of ethyl acetate The reaction was completed over 120 minutes, and after completion of the addition, the reaction was completed over 150 minutes. After completion of the reaction, the solution was diluted with toluene so that the solid content was 35% by mass to prepare a (meth) acrylic polymer solution. The term “solid content” means the amount of residue obtained by removing volatile components such as a solvent from a solution of a (meth) acrylic polymer.

Table 1 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), hydroxyl value (unit: mgKOH / g), and Tg (unit: ° C) of the obtained (meth) acrylic polymer. Shown in In Table 1, “weight average molecular weight” is simply expressed as “molecular weight”.
The weight average molecular weight (Mw) is measured by the method described above.
The hydroxyl value and Tg are calculated by the method described above.
Specifically, the hydroxyl value of the (meth) acrylic polymer obtained in Production Example 1 was calculated as follows. In addition, the content rate of 4HBA in all the monomers used for the (meth) acrylic-type polymer is 5.0 mass%, and the molecular weight of 4HBA is 144.2. The number of hydroxyl groups contained in one molecule of 2HEA and 4HBA is 1.
Hydroxyl value of the (meth) acrylic polymer obtained in Production Example 1 (mgKOH / g) = {(5.0 / 100) ÷ 144.2} × 56.1 × 1000 × 1 = 19.5

[Production Examples 2 to 8]
In each of Production Examples 2 to 8, the composition of the monomer in Production Example 1 was changed as shown in Table 1, and the amount of the solvent, the amount of the polymerization initiator, and the like were adjusted, as shown in Table 1, ( A (meth) acrylic polymer solution was prepared in the same manner as in Production Example 1 except that the weight average molecular weight of the (meth) acrylic polymer was adjusted.
Table 1 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), hydroxyl value (unit: mgKOH / g), and Tg (unit: ° C) of the obtained (meth) acrylic polymer. Shown in
The weight average molecular weight (Mw) is measured by the method described above.
The hydroxyl value and Tg are calculated by the method described above.

In Table 1, “MA” represents methyl acrylate, “LMA” represents lauryl methacrylate, and “2HEA” represents 2-hydroxyethyl acrylate.
The Tg described for each monomer in Table 1 is the Tg when the monomer is a homopolymer measured by the method described above.

[Production of (meth) acrylic oligomer]
[Production Example A]
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a sequential dropping device, 7 parts by mass of 2-ethylhexyl acrylate (2EHA) as alkyl acrylate and 2-hydroxyethyl acrylate (2HEA) 3 as a monomer having a hydroxyl group Parts by mass, 31.7 parts by mass of toluene, 31.7 parts by mass of methyl ethyl ketone (MEK), and 2,2′-azobis (isobutyric acid) dimethyl (trade name: V-601, Wako Pure Chemical Industries, Ltd.) as a polymerization initiator ) Made) 0.67 parts by mass was added and the temperature in the reaction vessel was increased while stirring until reflux occurred. Ten minutes after the start of reflux, 63 parts by mass of 2EHA, 27 parts by mass of 2HEA, 9.0 parts by mass of V-601, and 14.7 parts by mass of MEK were added dropwise over 90 minutes. After completion of the dropwise addition, the reaction was completed over 230 minutes. After completion of the reaction, the solution was diluted with toluene so that the solid content was 35% by mass to prepare a (meth) acrylic oligomer solution. “Solid content” means the amount of residue obtained by removing volatile components such as a solvent from a solution of a (meth) acrylic oligomer.

Table 2 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), and hydroxyl value (unit: mg KOH / g) of the obtained (meth) acrylic oligomer. In Table 2, “weight average molecular weight” is simply expressed as “molecular weight”.
The weight average molecular weight (Mw) is measured by the method described above.
The hydroxyl value is calculated by the method described above. Specifically, the hydroxyl value of the (meth) acrylic oligomer obtained in Production Example A was calculated as follows. In addition, the content rate of 2HEA in all the monomers used for the (meth) acrylic-type oligomer is 30.0 mass%, and the molecular weight of 2HEA is 116.1.
Hydroxyl value of the (meth) acrylic oligomer obtained in Production Example A (mgKOH / g) = {(30.0 / 100) ÷ 116.1} × 56.1 × 1000 × 1 = 145.0

[Production Examples B to D]
In each of Production Examples B to D, the composition of the monomer in Production Example A was changed as shown in Table 2, and by adjusting the amount of the solvent, the amount of the polymerization initiator, and the like, as shown in Table 2, ( A (meth) acrylic oligomer solution was prepared in the same manner as in Production Example A except that the weight average molecular weight of the (meth) acrylic oligomer was adjusted.
Table 2 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), and hydroxyl value (unit: mg KOH / g) of the obtained (meth) acrylic oligomer.
The weight average molecular weight (Mw) is measured by the method described above.
The hydroxyl value is calculated by the method described above.

“MA” in Table 2 represents methyl acrylate, “LMA” represents lauryl methacrylate, and “4HBA” represents 4-hydroxybutyl acrylate.
The Tg described for each monomer in Table 2 is the Tg when the monomer is a homopolymer measured by the method described above.

[Preparation of pressure-sensitive adhesive composition]
<Example 1>
95 parts by mass of the (meth) acrylic polymer solution prepared in Production Example 1 (solid content: 35% by mass) and 5% of the solution of the (meth) acrylic oligomer prepared in Production Example A (solid content: 35% by mass) 5 3.1 parts by mass ((meth) acrylic) of an isocyanate compound (trade name: Sumidur N3300, an isocyanate compound having an isocyanurate structure which is a trimer of hexamethylene diisocyanate, manufactured by Sumika Bayer Urethane Co., Ltd.) The isocyanate group contained in the isocyanate compound is 1.0 equivalent with respect to 1 equivalent of the total hydroxyl group contained in the hydroxyl group polymer and the hydroxyl group contained in the (meth) acrylic oligomer, and tackifier (trade name: YS Polystar TH130). Terpene phenolic tackifier, hydroxyl value: 60 mgKOH / g, 1 part by mass of Suhara Chemical Co., Ltd.) and a cross-linking catalyst (trade name: ADK STAB OT-1, dioctyltin dilaurate, active ingredient: 100 parts by mass, ADEKA Co., Ltd.) diluted 300 times with acetylacetone 4 2 parts by mass were mixed and sufficiently stirred to obtain the pressure-sensitive adhesive composition of Example 1. Table 3 shows the types of tackifiers used and the hydroxyl values. Table 4 shows details of the composition and the like of the obtained pressure-sensitive adhesive composition.
The total hydroxyl value in Table 4 is calculated by the method described above. Specifically, the total hydroxyl value of the pressure-sensitive adhesive composition of Example 1 was calculated as follows.
Total hydroxyl value (mgKOH / g) of the pressure-sensitive adhesive composition of Example 1 = 19.5 × {95 / (95 + 5 + 1)} + 145.0 × {5 / (95 + 5 + 1)} + 60 × {1 / (95 + 5 + 1)} = 26.1

[Preparation of test adhesive film]
Using the pressure-sensitive adhesive composition obtained above, a test pressure-sensitive adhesive film was produced as follows. On the polyethylene terephthalate (PET) film (trade name: Lumirror U35, thickness: 125 μm, manufactured by Toray Industries, Inc.), the pressure-sensitive adhesive composition was applied so that the coating amount after drying was 20 g / m ² . It dried for 60 seconds at 100 degreeC with the hot air circulation type dryer, and formed the layer of the adhesive composition. Next, the layer of the pressure-sensitive adhesive composition is in contact with a release film (trade name: Film Vina (registered trademark) 100E-0010NO23, manufactured by Fujimori Kogyo Co., Ltd.) whose surface is protected with a silicone-based release agent. A PET film was placed and bonded by pressing with a pressure nip roll. Thereafter, curing for terminating the cross-linking reaction was performed for 2 days in an environment of 23 ° C. and 50% RH, and a test pressure-sensitive adhesive film having a pressure-sensitive adhesive layer was produced.
Table 4 shows the gel fraction of the obtained pressure-sensitive adhesive layer. The gel fraction is measured by the method described above.

(Measurement and evaluation)
1. High-speed peelability after heat treatment The test adhesive film prepared above was cut into a size of 25 mm × 150 mm, the release film was peeled off from the obtained test adhesive film piece, and a hard-coated PET film (product) Name: KB film G01S, manufactured by Kimoto Co., Ltd.) and bonded to the hard-coated surface, a 2 kg rubber roll was reciprocated once and pressure-bonded to obtain a test piece. The test piece was allowed to stand for 1 hour in an environment of 23 ° C. and 50% RH, and then heat-treated in an environment of 150 ° C. for 1 hour, and then left to stand in an environment of 23 ° C. and 50% RH for 1 hour.
About the test piece after standing, the adhesive force (unit: N / 25mm) in 180 degree peeling at the time of peeling the test adhesive film in the long side (150mm) direction is the conditions of peeling speed 10m / min (high speed peeling). The high-speed peelability after the heat treatment was evaluated according to the following evaluation criteria. The results are shown in Table 4.

-Evaluation criteria-
A: When it exceeds 0.2 N / 25 mm and is 0.35 N / 25 mm or less (high-speed peelability is very excellent)
B: More than 0.1N / 25mm and 0.2N / 25mm or less, or more than 0.35N / 25mm and 0.4N / 25mm or less (high-speed peelability is excellent)
C: When it exceeds 0.05 / 25 mm and is 0.1 N / 25 mm or less, or when it exceeds 0.4 N / 25 mm and is 0.45 N / 25 mm or less (high-speed peelability is slightly inferior, but within an allowable range)
D: 0.05 / 25 mm or less, or when exceeding 0.45 N / 25 mm (high speed peelability is inferior and out of tolerance)

2. Peeling speed dependence About the test piece produced by the same method as the test piece used for the evaluation of the high-speed peelability after the heat treatment, the adhesive force at 180 ° peeling when the test adhesive film is peeled in the long side (150 mm) direction (unit: N / 25 mm) was measured under the condition of a peeling speed of 0.3 m / min (low speed peeling). And the value of the adhesive force in the case of this low-speed peeling, and the above 1. By applying the following formula to the value of the adhesive strength in the case of high-speed peeling measured in the high-speed peelability evaluation after the heat treatment, the peel rate dependency rate (%) is calculated, and according to the following evaluation criteria, The peel rate dependency was evaluated. In addition, it shows that peeling rate dependence is so high that the value of peeling rate dependence rate is high.
The results are shown in Table 4.
Peeling speed dependency rate (%) = (high speed peeling force / low speed peeling force) × 100

-Evaluation criteria-
A: When the peel rate dependency rate is 200% or less (the peel rate dependency is very low)
B: When the peeling rate dependency ratio exceeds 200% and is 270% or less (the peeling rate dependency is low)
C: When the peeling rate dependency rate exceeds 270% and is 300% or less (the peeling rate dependency is slightly high but within an allowable range)
D: When the peeling rate dependency rate exceeds 300% (the peeling rate dependency is high and out of the allowable range)

3. Contamination property In the evaluation of the high-speed peelability after the heat treatment, 2 μL of pure water was dropped on the hard coat-treated surface of the hard-coated PET film after the test adhesive film was peeled off from the test piece at high speed. After 2 seconds, the contact angle (θ1) of water was measured using a contact angle measurement device (device name: Drop Master DM-701, manufactured by Kyowa Interface Science Co., Ltd.).
Absolute value (Δθ = | θ1) of the difference between the obtained value and the value of the contact angle of water (θ0 = 84 °) measured in advance on the hard-coated surface without the test adhesive film attached -Θ0 |) was calculated. Then, the calculated absolute value (Δθ) was used as a contamination index and evaluated according to the following criteria. The results are shown in Table 4.

A: When Δθ is 2.0 or less (contamination is very low)
B: When Δθ exceeds 2.0 and is 4.5 or less (contamination is low)
C: When Δθ exceeds 4.5 and is 7.5 or less (contamination is slightly high)
D: When Δθ exceeds 7.5 (highly contaminating)

<Examples 2 to 26 and Comparative Examples 1 to 8>
In each of Examples 2 to 26 and Comparative Examples 1 to 8, types of (meth) acrylic polymer, (meth) acrylic oligomer, and tackifier in Example 1, (meth) acrylic polymer, and (meth) acrylic The blending ratio of the oligomer and the blending amount of the tackifier are as shown in Table 4, and the blending amount of the isocyanate compound is changed to a hydroxyl group contained in the (meth) acrylic polymer and a hydroxyl group contained in the (meth) acrylic oligomer. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the isocyanate group contained in the isocyanate compound was adjusted to the equivalent amount shown in Table 4 with respect to 1 equivalent of the total hydroxyl group. Table 3 shows the types of tackifiers used and the hydroxyl values.
Using the obtained pressure-sensitive adhesive composition, a test pressure-sensitive adhesive film was produced in the same manner as in Example 1. And about the produced adhesive film for a test, it carried out similarly to Example 1, and evaluated the high-speed peelability after heat processing, peeling rate dependence, and stain | pollution | contamination property. The results are shown in Table 4.

“-” In Tables 3 to 4 means that there is no corresponding item.
The hydroxyl values of tackifiers in Tables 3 to 4 are all catalog values disclosed by the manufacturer.
In Table 4, “isocyanate compound” is expressed as “crosslinking agent”.
“The ratio of the hydroxyl value of the acrylic resin to the hydroxyl value of the tackifier” in Table 4 is “the total of the hydroxyl value of the (meth) acrylic polymer and the hydroxyl value of the (meth) acrylic oligomer and the hydroxyl value of the tackifier”. Means the ratio.

The names of the tackifiers in Tables 3 and 4 and details of the manufacturer are as follows.
U115: YS Polystar U115 (trade name), manufactured by Yasuhara Chemical Co., Ltd. T100: YS Polystar T100 (trade name), manufactured by Yashara Chemical Co., Ltd. TH130: YS Polystar TH130 (trade name), manufactured by Yashara Chemical Co., Ltd. T160: YS Polystar T160 (Trade name), Yasuhara Chemical Co., Ltd. S145: YS Polystar S145 (trade name), Yashara Chemical Co., Ltd. D-6011: Pine Crystal D-6011 (trade name), Arakawa Chemical Industries, Ltd. TR105: YS Resin TR105 (trade name), manufactured by Yasuhara Chemical Co., Ltd. SX100: YS Resin SX100 (product name), manufactured by Yasuhara Chemical Co., Ltd.

As shown in Table 4, the pressure-sensitive adhesive compositions of Examples 1 to 27 were all evaluated to be excellent in high-speed peelability after heat treatment and low in peel rate dependency.
The pressure-sensitive adhesive composition of Comparative Example 1 containing no terpene phenol tackifier was inferior in the high-speed peelability after the heat treatment and highly dependent on the peel rate.
The pressure-sensitive adhesive compositions of Comparative Examples 2 to 4 including tackifiers other than the terpene phenol-based tackifier were all inferior in the high-speed peelability after the heat treatment and highly dependent on the peel rate.
The pressure-sensitive adhesive composition of Comparative Example 5 containing less than 0.1 part by mass of the terpene phenol-based tackifier with respect to 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer is subjected to heat treatment. The high-speed peelability was slightly inferior and the dependency on the peel rate was high.
The pressure-sensitive adhesive composition of Comparative Example 6 in which the content of the terpene phenolic tackifier with respect to 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer is higher than 5 parts by mass is high speed after the heat treatment. The peelability was inferior and the peel rate dependency was slightly high.
The pressure-sensitive adhesive composition of Comparative Example 7 in which the hydroxyl value of the (meth) acrylic polymer was lower than 10 mgKOH / g was inferior in the high-speed peelability after heat treatment, was highly dependent on the peel rate, and was highly contaminated. .
The pressure-sensitive adhesive composition of Comparative Example 8 having a total hydroxyl value higher than 85 mgKOH / g was inferior in high-speed peelability after heat treatment.

The pressure-sensitive adhesive composition of Example 1 containing both the (meth) acrylic polymer and the (meth) acrylic oligomer was heated in comparison with the pressure-sensitive adhesive composition of Example 26 not containing the (meth) acrylic oligomer. Excellent high-speed peelability after treatment.
In the pressure-sensitive adhesive composition (for example, Examples 1, 10, 11, etc.) in which the hydroxyl value of the (meth) acrylic oligomer is 70 mgKOH / g or more, compared with the pressure-sensitive adhesive composition of Example 9 lower than 70 mgKOH / g. There was a tendency for contamination to be low.

Claims (7)

A (meth) acrylic polymer containing a structural unit derived from a monomer having a hydroxyl group, having a hydroxyl value of 10 mgKOH / g or more and a weight average molecular weight of 300000 or more and 1800000 or less,
An isocyanate compound;
Including terpene phenolic tackifier,
The content of the terpene phenol tackifier with respect to 100 parts by mass of the (meth) acrylic polymer is 0.1 parts by mass or more and 5 parts by mass or less.
The adhesive composition whose sum total of the hydroxyl value computed by following formula (1) is 10 mgKOH / g or more and 85 mgKOH / g or less.
Including a structural unit derived from a monomer having a hydroxyl group, further comprising a (meth) acrylic oligomer having a hydroxyl value of 70 mgKOH / g or more and a weight average molecular weight of 1,000 to 30,000,
The ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass or more and 40% by mass or less,
The content of the terpene phenol tackifier is the content of the terpene phenol tackifier with respect to a total of 100 parts by mass of the (meth) acrylic polymer and the (meth) acrylic oligomer,
The total hydroxyl value calculated by the above formula (1) is the total hydroxyl value calculated by the following formula (2).
The pressure-sensitive adhesive composition according to claim 1, wherein the total hydroxyl value calculated by the following formula (2) is 15 mgKOH / g or more and 85 mgKOH / g or less.
  The content of the isocyanate compound is such that the isocyanate group is 0.5 equivalent or more to the total of 1 equivalent of the hydroxyl group contained in the (meth) acrylic polymer and the hydroxyl group contained in the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to claim 2, wherein the pressure-sensitive adhesive composition is in an amount of 0 equivalent or less.   The (meth) acrylic oligomer has a structural unit derived from a monomer having a glass transition temperature (Tg) of −50 ° C. or less when a homopolymer is used, with respect to all structural units of the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to claim 2 or 3, comprising 50% by mass or more.   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein a glass transition temperature (Tg) of the (meth) acrylic polymer is -50 ° C or lower.   The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the terpene phenol-based tackifier has a hydroxyl value of 20 mgKOH / g or more and 160 mgKOH / g or less.   An adhesive film provided with a base material and the adhesive layer which is provided on the said base material and originates in the adhesive composition of any one of Claims 1-6.