JP2021046532A - Adhesive sheet - Google Patents

Abstract

To provide an adhesive sheet that maintains satisfactory adhesive force even in the case of having passed through a process of applying heat, is difficult to cause adhesive residue on an adherend in peeling the sheet even in the case where the sheet is used for a long period of time, and has excellent thermal resistance and transparency.SOLUTION: A adhesive sheet comprises a base material and an adhesive layer arranged on the base material, the base material contains vinyl chloride-based resin, resin having epoxy group, and polyester-based plasticizer, and in which an epoxy functional group amount of resin having the epoxy group with respect to 100 pts.mass of the vinyl chloride-based resin is 0.005 mol to 0.05 mol, the adhesive layer is formed of adhesive composition including (meth)acrylic copolymer which includes a constitutional unit derived from (meth)acrylic acid alkyl ester monomer and a constitutional unit derived from monomer having carboxy group, and 0.1 pts.mass to 2.0 pts.mass of metal chelate-based cross-linking agent with respect to 100 pts.mass of the (meth)acrylic copolymer.SELECTED DRAWING: None

Description

The present invention relates to an adhesive sheet.

Adhesive sheets provided with a base material containing a vinyl chloride resin have excellent flexibility and printability, and also have good weather resistance. Therefore, decorative stickers for vehicles (for example, automobiles and motorcycles), various signs, and various types. Widely used for signs and the like. In an adhesive sheet provided with a base material containing a vinyl chloride resin, flexibility is generally imparted by blending a plasticizer, and heat resistance is improved by blending a heat stabilizer.

For example, Patent Document 1 describes vinyl chloride-based polymers, polyester-based plasticizers, epoxy resins, at least one metal soap selected from fatty acid calcium, fatty acid zinc, and fatty acid barium, and hydrotalcite. A base film for an adhesive sheet comprising the above is disclosed. According to the description of Patent Document 1, a combination of an epoxy resin having a specific weight average molecular weight, metallic soap, and hydrotalcite functions as a heat stabilizer.
Further, Patent Document 2 describes a (meth) acrylic acid ester monomer having an alkyl group of C4 to C8, a radical polymer monomer having a carboxy group, and a vinyl chloride resin film containing a plasticizer. A decorative pressure-sensitive adhesive sheet is disclosed in which a pressure-sensitive adhesive layer formed of an acrylic copolymer composed of vinyl acetate and methyl acrylate and a pressure-sensitive adhesive composition containing a metal chelate cross-linking agent is laminated. There is.

Japanese Unexamined Patent Publication No. 2001-106990 Japanese Unexamined Patent Publication No. 2006-199843

In recent years, it has been studied to apply an adhesive sheet having a base material containing a vinyl chloride resin to a protective film [so-called PPF (paint protection film)] for protecting a painted surface of a vehicle. Since the PPF uses the vehicle as an adherend, it is required to follow the three-dimensional shape well. Therefore, even in the pressure-sensitive adhesive sheet applied to PPF, flexibility is imparted by blending a plasticizer with the base material.
However, in the pressure-sensitive adhesive sheet provided with the base material containing the plasticizer, when heat is applied, the plasticizer in the base material tends to move to the pressure-sensitive adhesive layer. For example, the surface of an adhesive sheet applied to a PPF, a decorative sticker, or the like is often provided with a decorative layer for imparting design, a functional layer for imparting antifouling properties, and the like. In the step of providing such a layer, for example, heat may be applied to the pressure-sensitive adhesive sheet because it undergoes a drying step.
When the plasticizer in the base material is transferred to the pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer can be reduced. Further, when the plasticizer in the base material is transferred to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer becomes soft. Therefore, when the pressure-sensitive adhesive sheet is peeled off from the adherend after use, the pressure-sensitive adhesive layer is transferred to the adherend (so-called so-called). There may be a problem of adhesive residue. For example, an adhesive sheet applied to PPF is peeled off from the vehicle after being used for a long period of time (for example, 3 years), but when the plasticizer is transferred to the pressure-sensitive adhesive layer, adhesive residue is likely to occur on the vehicle during peeling. .. Further, the heat stabilizer to be blended in the base material for improving the heat resistance may also be transferred to the pressure-sensitive adhesive layer, which may cause a decrease in the adhesive strength of the pressure-sensitive adhesive layer.

Therefore, for an adhesive sheet provided with a base material containing a vinyl chloride resin, a plasticizer, and a heat stabilizer, good adhesive strength is maintained even after a process of applying heat, and a long period of time is maintained. Even when used, it is required that adhesive residue on the adherend is unlikely to occur during peeling.

Further, when the pressure-sensitive adhesive sheet provided with the base material containing the vinyl chloride resin is used outdoors, there may be a problem that the vinyl chloride resin deteriorates with time and turns yellow.
Therefore, the pressure-sensitive adhesive sheet provided with the base material containing the vinyl chloride resin is required to be less likely to turn yellow even when exposed to a high temperature environment for a long period of time.
Further, for example, the pressure-sensitive adhesive sheet applied to PPF is generally required to be transparent.

The problem to be solved by the present invention is that good adhesive strength is maintained even after a process of applying heat, and even when used for a long period of time, adhesive residue on the adherend is unlikely to occur at the time of peeling. To provide an adhesive sheet having excellent heat resistance and transparency.

Specific means for solving the problem include the following aspects.
<1> A base material and an adhesive layer arranged on the base material are provided.
The base material contains a vinyl chloride resin, a resin having an epoxy group, and a polyester plastic agent, and the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0. It is a base material of 005 mol to 0.05 mol, and is
The pressure-sensitive adhesive layer includes a (meth) acrylic copolymer containing a structural unit derived from a (meth) acrylic acid alkyl ester monomer and a structural unit derived from a monomer having a carboxy group, and the above (meth). A pressure-sensitive adhesive sheet, which is a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing 0.1 parts by mass to 2.0 parts by mass of a metal chelate-based cross-linking agent with respect to 100 parts by mass of an acrylic copolymer.
<2> The content of the structural unit derived from the monomer having a carboxy group in the (meth) acrylic copolymer is 0.5 with respect to all the structural units of the (meth) acrylic copolymer. The adhesive sheet according to <1>, which is by mass% to 15% by mass.
<3> The pressure-sensitive adhesive sheet according to <1> or <2>, wherein the content of the polyester-based plasticizer in the base material is 15 parts by mass to 65 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. ..
<4> The pressure-sensitive adhesive sheet according to any one of <1> to <3>, wherein the resin having an epoxy group has a weight average molecular weight of 5,000 to 100,000.
<5> The pressure-sensitive adhesive sheet according to any one of <1> to <4>, wherein the resin having an epoxy group is an acrylic resin.
<6> Amount of epoxy functional group of the resin having the epoxy group in the base material with respect to the molar ratio of the carboxy group in the (meth) acrylic copolymer [that is, the resin having the epoxy group in the base material The adhesive according to any one of <1> to <5>, wherein the amount of epoxy functional group / molar ratio of carboxy group in the (meth) acrylic copolymer] is 0.024 to 7.210. Sheet.
<7> The pressure-sensitive adhesive sheet according to any one of <1> to <6>, wherein the thickness of the base material is 50 μm to 300 μm.
<8> The adhesive sheet according to any one of <1> to <7>, wherein the adherend surface is a painted surface of a vehicle.

According to the present invention, good adhesive strength is maintained even after a process of applying heat, and even when used for a long period of time, adhesive residue on the adherend is unlikely to occur at the time of peeling, and heat resistance and heat resistance An adhesive sheet having excellent transparency is provided.

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

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

In the present specification, the "(meth) acrylic copolymer" means that the content of the structural unit derived from the monomer having a (meth) acryloyl group is the total structural unit [that is, the (meth) acrylic copolymer]. It means a copolymer which is 50% by mass or more of [the total structural unit of the polymer].

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

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

In the present invention, "heat resistance" means a property that does not easily turn yellow even when exposed to a high temperature environment for a long period of time. The "high temperature environment" here is assumed to be an outdoor environment, but in the examples, the heat resistance of the adhesive sheet is evaluated by a heating acceleration test in which the adhesive sheet is allowed to stand in an environment of 200 ° C.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention comprises a base material and a pressure-sensitive adhesive layer arranged on the base material.
The base material contains a vinyl chloride resin, a resin having an epoxy group, and a polyester plastic agent, and the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0. It is a base material of 005 mol to 0.05 mol, and is
The pressure-sensitive adhesive layer is a (meth) acrylic copolymer containing a structural unit derived from a (meth) acrylic acid alkyl ester monomer and a structural unit derived from a monomer having a carboxy group. It is also called "meth) acrylic copolymer". ] And a pressure-sensitive adhesive layer containing 0.1 parts by mass to 2.0 parts by mass of a metal chelate-based cross-linking agent with respect to 100 parts by mass of the (meth) acrylic copolymer. Is.
The adhesive sheet of the present invention maintains good adhesive strength even after undergoing a process of applying heat, is less likely to leave adhesive residue on the adherend during peeling even after long-term use, and has heat resistance. And excellent in transparency.
Although it is not clear why the pressure-sensitive adhesive sheet of the present invention can exert such an effect, the present inventors speculate as follows. However, the following speculation does not limit the interpretation of the pressure-sensitive adhesive sheet of the present invention, but is described as an example.

^{In general, a compound having an epoxy group captures H +} and Cl ⁻ derived mainly from HCl generated by heating when processing a vinyl chloride resin into a film, and discolors the vinyl chloride resin (specifically, in detail. , Yellowing), functions as a so-called heat stabilizer. Conventionally, epoxidized soybean oil is often used as a heat stabilizer which is a compound having an epoxy group.
On the other hand, the base material in the present invention contains a resin having an epoxy group. The resin having an epoxy group functions as a heat stabilizer for the vinyl chloride resin. Since the amount of the epoxy functional group of the resin having an epoxy group is a specific amount or more, the pressure-sensitive adhesive sheet of the present invention is excellent in heat resistance. Further, the resin having an epoxy group is less likely to move from the base material to the pressure-sensitive adhesive layer as compared with a low molecular weight compound such as epoxidized soybean oil. Therefore, it is presumed that the pressure-sensitive adhesive sheet of the present invention maintains good adhesive strength even after undergoing a process of applying heat.
Further, the pressure-sensitive adhesive layer in the present invention has a specific range with respect to a specific (meth) acrylic copolymer containing a structural unit derived from a monomer having a carboxy group and a specific (meth) acrylic copolymer. It is a pressure-sensitive adhesive layer formed by a pressure-sensitive adhesive composition containing an amount of a metal chelate-based cross-linking agent. The metal chelate-based cross-linking agent has a fast cross-linking reaction and rapidly and sufficiently cross-links with the carboxy group of the constituent unit derived from the monomer having a carboxy group to plasticize the base material to the pressure-sensitive adhesive layer. Drug transfer is suppressed. Therefore, it is presumed that the pressure-sensitive adhesive sheet of the present invention maintains good adhesive strength even after undergoing a process of applying heat.
In the pressure-sensitive adhesive sheet of the present invention, a part of the epoxy groups of the resin having an epoxy group in the base material is present near the interface with the pressure-sensitive adhesive layer of the base material, and the monomer having a carboxy group in the pressure-sensitive adhesive layer. It is considered that a part of the carboxy group of the structural unit derived from is present near the interface of the pressure-sensitive adhesive layer with the base material. In the pressure-sensitive adhesive sheet of the present invention, the epoxy group existing near the interface between the base material and the pressure-sensitive adhesive layer and the carboxy group existing near the interface between the base material and the pressure-sensitive adhesive layer are the interface between the base material and the pressure-sensitive adhesive layer. It is presumed that adhesive residue on the adherend is unlikely to occur during peeling even when used for a long period of time because the adhesion between the base material and the pressure-sensitive adhesive layer is improved.

DOP [bis (bis (2-ethylhexyl) phthalate)] is often used as a plasticizer for vinyl chloride resins. On the other hand, the base material in the present invention contains a polyester-based plasticizer. Polyester-based plasticizers are less likely to migrate from the substrate to the pressure-sensitive adhesive layer than low-molecular-weight compounds such as DOP. Therefore, it is presumed that the pressure-sensitive adhesive sheet of the present invention maintains good adhesive strength and suppresses a decrease in the flexibility of the base material even after undergoing a process of applying heat. Further, in the pressure-sensitive adhesive sheet of the present invention, since the transfer of the plasticizer from the base material to the pressure-sensitive adhesive layer is suppressed, the pressure-sensitive adhesive layer contains the plasticizer and becomes soft, resulting in an adherend at the time of peeling. It is presumed that the generation of adhesive residue on the surface is suppressed.

Further, since the pressure-sensitive adhesive sheet of the present invention has an epoxy functional group amount of a resin having an epoxy group of a specific amount or less, it is presumed that the transparency is not impaired and the transparency is excellent.

〔Base material〕
The pressure-sensitive adhesive sheet of the present invention comprises a base material.
The base material provided in the pressure-sensitive adhesive sheet of the present invention contains a vinyl chloride resin, a resin having an epoxy group, and a polyester plasticizer, and the epoxy functionality of the resin having the epoxy group with respect to 100 parts by mass of the vinyl chloride resin. The base amount is 0.005 mol to 0.05 mol.

<Vinyl chloride resin>
The base material provided in the pressure-sensitive adhesive sheet of the present invention contains a vinyl chloride resin.
As used herein, the term "vinyl chloride-based resin" means a polymer containing a structural unit derived from vinyl chloride. Further, the "constituent unit derived from vinyl chloride" means a structural unit formed by addition polymerization of vinyl chloride.

Examples of the vinyl chloride resin include a homopolymer of vinyl chloride (that is, polyvinyl chloride), and vinyl chloride and other monomers (specifically, other monomers copolymerizable with vinyl chloride). ), And examples thereof.
Other monomers copolymerizable with vinyl chloride include, for example, vinyl ester compounds typified by vinyl acetate and vinyl propionate, olefin compounds typified by ethylene and propylene, methyl acrylate, ethyl acrylate, and the like. (Meta) acrylic acid ester compounds represented by methyl methacrylate, maleic acid diester compounds represented by dibutyl maleate and diethyl maleate, fumaric acid diester compounds represented by dibutyl fumarate and diethyl fumarate, acrylonitrile and methacrylate. Examples thereof include vinyl cyanide compounds typified by acrylonitrile, vinyl halide compounds typified by vinylidene chloride and vinyl bromide, and vinyl ether compounds typified by methyl vinyl ether and ethyl vinyl ether.

The content rate (that is, ratio; hereinafter the same) of the constituent units derived from vinyl chloride in the vinyl chloride resin is not particularly limited, but is, for example, 50% by mass or more with respect to all the constituent units of the vinyl chloride resin. It is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, and 80% by mass. It is more preferably% to 100% by mass, and particularly preferably 90% by mass to 100% by mass.

The average degree of polymerization of the vinyl chloride resin is not particularly limited, but is preferably 500 to 1700, more preferably 700 to 1400, and even more preferably 800 to 1300, for example.
When the average degree of polymerization of the vinyl chloride resin is within the above range, the base material exhibits appropriate flexibility and is firm, so that the releasability from the adherend tends to be better. ..
The average degree of polymerization of the vinyl chloride resin is a value measured by a method according to JIS K6721. As described later, a commercially available product can be used as the vinyl chloride resin. When a commercially available product is used as the vinyl chloride resin, the average degree of polymerization of the vinyl chloride resin is adopted with priority given to the catalog value of the commercially available product.

As the vinyl chloride resin, a commercially available product can be used.
Examples of commercially available vinyl chloride resins include Kanevinyl (registered trademark) S1001N [trade name, average degree of polymerization: 1050, Kaneka Co., Ltd.], Kanevinyl (registered trademark) S1008 [trade name, average degree of polymerization: 800, Kaneka Co., Ltd.], Kanevinyl (registered trademark) S1003 [trade name, average degree of polymerization: 1300, Kaneka Co., Ltd.], ZEST PQLT [trade name, average degree of polymerization: 800, Shin Daiichi PVC Co., Ltd. ], ZEST P31D [trade name, average degree of polymerization: 1000, Shin Daiichi PVC Co., Ltd.], ZEST PQHC [trade name, average degree of polymerization: 1300, Shin Daiichi PVC Co., Ltd.], TK-1000 [trade name] , Average degree of polymerization: 1030, Shin-Etsu Chemical Industry Co., Ltd.], TK-800 [Product name, Average degree of polymerization: 800, Shin-Etsu Chemical Industry Co., Ltd.], TK-1300 [Product name, Average degree of polymerization: 1300, Shin-Etsu Chemical Industry Co., Ltd.] and the like.

The base material may contain only one type of vinyl chloride resin, or may contain two or more types.

The content of the vinyl chloride resin in the base material is not particularly limited, but is preferably 55% by mass to 90% by mass and 60% by mass to 85% by mass with respect to the total mass of the base material, for example. More preferably, it is more preferably 65% by mass to 80% by mass.
When the content of the vinyl chloride resin in the base material is within the above range with respect to the total mass of the base material, the base material tends to exhibit appropriate flexibility.

<Resin with epoxy group>
The base material provided in the pressure-sensitive adhesive sheet of the present invention contains a resin having an epoxy group.
The resin having an epoxy group contributes as a heat stabilizer.

The type of resin having an epoxy group is not particularly limited.
Examples of the resin having an epoxy group include an acrylic resin, a resin which is a reaction product of bisphenol and epichlorohydrin, a polyester resin, and a silicone resin.
Among these, an acrylic resin is preferable as the resin having an epoxy group.
When the resin having an epoxy group is an acrylic resin, the compatibility with the vinyl chloride resin is better, and the appearance and transparency of the pressure-sensitive adhesive sheet tend to be better.

As used herein, the term "acrylic resin" means a polymer containing a structural unit derived from a monomer having a (meth) acryloyl group. Further, the “constituent unit derived from the (meth) acrylic monomer” means a structural unit formed by addition polymerization of a monomer having a (meth) acryloyl group.
Examples of the acrylic resin include a copolymer of a monomer having a (meth) acryloyl group, and a monomer having a (meth) acryloyl group and another monomer (specifically, a (meth) acryloyl group. Examples thereof include a copolymer of a monomer having and copolymerizable with another monomer.
The monomer having a (meth) acryloyl group is not particularly limited, and examples thereof include the (meth) acrylic acid alkyl ester monomer described later.
The content of the structural unit derived from the monomer having a (meth) acryloyl group in the acrylic resin is not particularly limited, and is, for example, 50% by mass or more with respect to all the structural units of the acrylic resin. It is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, and 80% by mass to 100% by mass. It is more preferably%, and particularly preferably 90% by mass to 100% by mass.

The weight average molecular weight (Mw) of the resin having an epoxy group is not particularly limited, but is preferably, for example, 5,000 to 100,000, more preferably 10,000 to 100,000, and 30,000 to 10. It is more preferably 10,000, and particularly preferably 50,000 to 100,000.
When the weight average molecular weight of the resin having an epoxy group is 5,000 or more, the migration to the pressure-sensitive adhesive layer tends to be further suppressed.
When the weight average molecular weight of the resin having an epoxy group is 100,000 or less, the compatibility with the vinyl chloride resin is better, and the appearance and transparency of the pressure-sensitive adhesive sheet tend to be better.

The weight average molecular weight of the resin having an epoxy group is a value measured as a standard polystyrene-equivalent value under the following conditions using gel permeation chromatography (GPC). As described later, a commercially available product can be used as the resin having an epoxy group. When a commercially available product is used as the resin having an epoxy group, the weight average molecular weight of the resin having an epoxy group is adopted with priority given to the catalog value of the commercially available product.

~conditions~
Measuring device: High-speed GPC [Model number: HLC-8020 GPC, Tosoh Corporation]
Detector: Differential Refractometer (RI) [Built-in to HLC-8220, Tosoh Corporation]
Column: TSKguardcolumnH _XL- H [trade name, Tosoh Corporation] 1 bottle,
TSKgel-GMH _XL [trade name, Tosoh Corporation] 2 bottles and
TSKgel-G2000 _XL [Product name, Tosoh Corporation] 1 column size: 7.8 mm ID x 30 cm
Column temperature: 38 ° C
Eluent: tetrahydrofuran Sample concentration: 4 mg / mL
Injection volume: 100 μL
Flow rate: 0.8 mL / min

As the resin having an epoxy group, a commercially available product can be used.
Examples of commercially available resins having an epoxy group include Metabrene (registered trademark) P-1901 [trade name, weight average molecular weight: 68000, epoxy equivalent (catalog value): 170 g / eq, acrylic resin, Mitsubishi Chemical Co., Ltd. )], Marproof (registered trademark) G-01100 [Product name, weight average molecular weight: 12000, epoxy equivalent (catalog value): 170 g / eq, acrylic resin, Nichiyu Co., Ltd.], Marproof (registered trademark) G-0150M [Product name, weight average molecular weight: 10000, epoxy equivalent (catalog value): 310 g / eq, acrylic resin, Nichiyu Co., Ltd.], Marproof (registered trademark) G-0130SP [Product name, weight average Molecular weight: 9000, epoxy equivalent (catalog value): 530 g / eq, acrylic resin, Nichiyu Co., Ltd.] and the like.

The base material may contain only one type of resin having an epoxy group, or may contain two or more types of resin.

The amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0.005 mol to 0.05 mol, preferably 0.008 mol to 0.05 mol, and 0.010. It is more preferably mol to 0.05 mol, and even more preferably 0.012 mol to 0.05 mol.
When the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0.005 mol or more, an adhesive sheet having excellent heat resistance can be realized.
When the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0.05 mol or less, an adhesive sheet having excellent transparency can be realized.

In the present specification, the "epoxy functional group amount" is a value obtained by dividing the number of parts containing an epoxy group (unit: parts by mass) with respect to 100 parts by mass of a vinyl chloride resin by the epoxy equivalent of the resin having an epoxy group. Means.
The epoxy equivalent (molecular weight / number of epoxy groups, unit: g / eq) of the resin having an epoxy group is a value measured by a method according to JIS K 7236: 2009. When a commercially available product is used as the resin having an epoxy group, the epoxy equivalent of the resin having an epoxy group is adopted with priority given to the catalog value of the commercially available product.

The content of the resin having an epoxy group in the base material is particularly high as long as the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0.005 mol to 0.05 mol. Not limited.
The content of the resin having an epoxy group in the base material is preferably, for example, 1 part by mass to 10 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.

<Polyester plasticizer>
The base material provided in the pressure-sensitive adhesive sheet of the present invention contains a polyester-based plasticizer.
The polyester-based plasticizer contributes to imparting flexibility to the base material.

The polyester-based plasticizer is not particularly limited, and examples thereof include phthalic acid-based polyester, adipic acid-based polyester, and sebacic acid-based polyester.
Among these, as the polyester-based plasticizer, at least one selected from the group consisting of adipic acid-based polyester and sebacic acid-based polyester is preferable, and adipic acid-based polyester is more preferable.
As the polyester, a polyalkylene glycol diester is preferable.
Examples of the polyalkylene glycol diester include polyethylene glycol diester, polypropylene glycol diester, and polyethylene polypropylene glycol diester.

The number average molecular weight of the polyester-based plasticizer is not particularly limited, but is preferably, for example, 1000 to 3000, more preferably 1200 to 3000, and even more preferably 1500 to 3000.
When the number average molecular weight of the polyester-based plasticizer is within the above range, the transfer of the polyester-based plasticizer from the base material to the pressure-sensitive adhesive layer tends to be more suppressed when the pressure-sensitive adhesive sheet is used for a long period of time.

The number average molecular weight (Mn) of the polyester-based plasticizer is a value measured as a standard polystyrene-equivalent value under the following conditions using gel permeation chromatography (GPC). As described later, a commercially available product can be used as the polyester-based plasticizer. When the polyester-based plasticizer is a commercially available product, the number average molecular weight (Mn) of the polyester-based plasticizer is adopted with priority given to the catalog data of the commercially available product.

~conditions~
Measuring device: High-speed GPC [Model number: HLC-8020 GPC, Tosoh Corporation]
Detector: Differential Refractometer (RI) [Built-in to HLC-8220, Tosoh Corporation]
Column: TSKguardcolumnH _XL- H [trade name, Tosoh Corporation] 1 bottle,
TSKgel-GMH _XL [trade name, Tosoh Corporation] 2 bottles and
TSKgel-G2000 _XL [Product name, Tosoh Corporation] 1 column size: 7.8 mm ID x 30 cm
Column temperature: 38 ° C
Eluent: tetrahydrofuran Sample concentration: 4 mg / mL
Injection volume: 100 μL
Flow rate: 0.8 mL / min

As the polyester-based plasticizer, a commercially available product can be used.
Examples of commercially available polyester-based plasticizers include ADEKA CORPORATION (registered trademark) PN-350 [trade name, number average molecular weight: 3000, ADEKA Corporation], ADEKA CORPORATION (registered trademark) PN-446 [trade name, Number average molecular weight: 2000, ADEKA Corporation], ADEKA CORPORATION (registered trademark) PN-150 [trade name, number average molecular weight: 1000, ADEKA Corporation], D623 [trade name, number average molecular weight: about 1800, Mitsubishi Chemical Co., Ltd.], D645 [trade name, number average molecular weight: about 2200, Mitsubishi Chemical Co., Ltd.] and the like. All of the above-mentioned commercially available products are adipic acid-based polyesters.

The base material may contain only one type of polyester plasticizer, or may contain two or more types.

The content of the polyester-based plasticizer in the base material is not particularly limited, but is preferably 15 parts by mass to 65 parts by mass, and 20 parts by mass to 60 parts by mass, for example, with respect to 100 parts by mass of the vinyl chloride resin. It is more preferably 25 parts by mass to 55 parts by mass, and particularly preferably 25 parts by mass to 50 parts by mass.
When the content of the polyester-based plasticizer in the base material is 15 parts by mass or more with respect to 100 parts by mass of the vinyl chloride resin, the base material becomes more flexible, so that the adherend having a three-dimensional shape (for example, It tends to be easier for the adhesive sheet to follow the vehicle (vehicles such as automobiles and motorcycles), and it tends to be possible to further suppress the floating from the adherend after sticking.
When the content of the polyester-based plasticizer in the base material is 65 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin, the elastic modulus of the base material becomes appropriate, so that the adherend having a three-dimensional shape ( For example, there is a tendency that the sticking work on vehicles such as automobiles and motorcycles can be further improved.

<Other ingredients>
The base material provided in the pressure-sensitive adhesive sheet of the present invention may contain components other than the above-mentioned components (so-called other components), if necessary, as long as the effects of the present invention are not impaired.
Other components include stabilizers, lubricants, antistatic agents, processing aids, colorants, colorants, UV absorbers, modifiers, fillers, diluents and the like.

The stabilizer is not particularly limited, and is, for example, a barium-based stabilizer, a calcium-based stabilizer, a tin-based stabilizer, a zinc-based stabilizer, and a composite stabilizer [for example, a calcium / zinc-based (Ca / Zn-based) stabilizer. , And barium / zinc-based (Ba / Zn-based) stabilizers] and other stabilizers. Further, metallic soap (for example, fatty acid calcium, fatty acid zinc, and fatty acid barium), silica compounds, and the like can also function as stabilizers.
When the base material contains a stabilizer, the base material may contain only one type of stabilizer, or may contain two or more types of stabilizer.

The lubricant is not particularly limited, and is, for example, a metal soap-based lubricant (for example, zinc stearate, zinc myristate, aluminum stearate, and calcium stearate), a fatty acid ester-based lubricant (for example, butyl stearate, butyl laurate, etc.). And stearyl stearate), fatty acid lubricants (eg stearic acid, behenic acid, and montanic acid), amide lubricants (eg ethylene bisstearoamide, erucic acid amide, oleic acid amide, stearic acid amide, and behenic acid). Examples thereof include lubricants such as amide) and hydrocarbon-based lubricants (for example, liquid paraffin, paraffin wax, and polyethylene wax). In addition, anionic surfactants can also function as lubricants.
When the base material contains a lubricant, it may contain only one type of lubricant, or may contain two or more types of lubricant.

[Method for producing base material]
The method for producing the base material in the present invention is not particularly limited.
An example of a preferable method for producing a base material in the present invention will be described in detail. The details of the matters common to the above-mentioned base material, for example, the material of the base material and the amount thereof will be omitted.

A vinyl chloride-based resin, a resin having an epoxy group, a polyester-based plasticizer, and, if necessary, other components such as a stabilizer and a lubricant are mixed to obtain a mixture.
The mixing means is not particularly limited, and examples thereof include a mixing device such as a ribbon blender, a Henschel mixer, a V-type blender, and a tumble mixer.
The mixing temperature is not particularly limited and can be appropriately set according to, for example, the type and amount of the material.
The mixing time is not particularly limited and can be appropriately set according to, for example, the type and amount of the material.

Then, the obtained mixture is melt-kneaded to obtain a melt-kneaded product.
The melt-kneading means is not particularly limited, and examples thereof include a single-screw (so-called single-screw) kneading extruder, a twin-screw kneading extruder, and a melt-kneading machine such as two rolls.
The conditions for melt-kneading are not particularly limited and can be appropriately set according to the type of material, for example.

Next, the obtained melt-kneaded product is used to form a film to obtain a base material.
The method for forming the film-like base material is not particularly limited, and for example, an extrusion method is preferable, and a T-die method is more preferable.
For the extrusion method, a single-screw extruder with a T-die can be preferably used.
The cylinder temperature is not particularly limited and can be set to, for example, 140 ° C to 180 ° C.
The die temperature is not particularly limited and can be set to, for example, 180 ° C. to 220 ° C.

The thickness of the base material in the present invention is not particularly limited and can be appropriately set according to the intended purpose.
The thickness of the base material in the present invention is, for example, preferably 50 μm to 300 μm, more preferably 50 μm to 250 μm, further preferably 100 μm to 250 μm, and particularly preferably 100 μm to 200 μm.
When the thickness of the base material in the present invention is 50 μm or more, the contents of the resin having an epoxy group and the polyester-based plasticizer are relatively large. The pressure-sensitive adhesive sheet of the present invention tends to be less likely to cause problems such as a decrease in adhesive strength and generation of adhesive residue due to these additives even if the thickness of the base material is 50 μm or more.
When the thickness of the base material in the present invention is 300 μm or less, the adhesive sheet tends to be more easily followed by an adherend having a three-dimensional shape (for example, a vehicle such as an automobile or a motorcycle).

[Adhesive layer]
The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer arranged on the above-mentioned base material.
The pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing a specific (meth) acrylic copolymer and a specific amount of a metal chelate-based cross-linking agent.

<Adhesive composition>
The pressure-sensitive adhesive composition in the present invention contains a specific (meth) acrylic copolymer and a specific amount of a metal chelate-based cross-linking agent.
Hereinafter, each component of the pressure-sensitive adhesive composition will be described in detail.

<< Specific (meth) acrylic copolymer >>
The pressure-sensitive adhesive composition in the present invention contains a specific (meth) acrylic copolymer.
The specific (meth) acrylic copolymer contains a (meth) acrylic acid alkyl ester monomer-derived structural unit and a (meth) acrylic acid-based copolymer containing a structural unit derived from a monomer having a carboxy group. Including coalescence.

-Constituent unit derived from (meth) acrylic acid alkyl ester monomer-
The specific (meth) acrylic copolymer contains a structural unit derived from the (meth) acrylic acid alkyl ester monomer.
The structural unit derived from the (meth) acrylic acid alkyl ester monomer contributes to the adjustment of adhesive strength.

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

The type of (meth) acrylic acid alkyl ester monomer is not particularly limited.
As the (meth) acrylic acid alkyl ester monomer, an unsubstituted (meth) acrylic acid alkyl ester monomer is preferable.
The alkyl group of the (meth) acrylic acid alkyl ester monomer may be linear, branched or cyclic.
The number of carbon atoms of the alkyl group is, for example, preferably 1 to 18 and more preferably 1 to 12 from the viewpoint of adhesive strength.

Specific examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and s-butyl (meth). Acrylate, t-butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (meth) acrylate, Examples thereof include n-decyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
Examples of the (meth) acrylic acid alkyl ester monomer include n-butyl acrylate (n-BA), methyl acrylate (MA), and 2-ethylhexyl acrylate (from the viewpoint of easily adjusting the cohesive force and adhesive force). At least one selected from the group consisting of 2EHA) is preferable.

The specific (meth) acrylic copolymer may contain only one type of structural unit derived from the (meth) acrylic acid alkyl ester monomer, or may contain two or more types.

The content of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer is not particularly limited, but for example, all the structural units of the specific (meth) acrylic copolymer. On the other hand, it is preferably 50% by mass or more, more preferably 50% by mass to 99.5% by mass, further preferably 60% by mass to 99.5% by mass, and 70% by mass to 70% by mass. It is more preferably 99.5% by mass, further preferably 80% by mass to 99.5% by mass, and particularly preferably 85% by mass to 99.5% by mass.
Here, the fact that the content of the structural unit derived from the (meth) acrylic acid alkyl ester monomer is 50% by mass or more with respect to all the structural units of the specific (meth) acrylic copolymer is (meth). ) It means that the structural unit derived from the acrylic acid alkyl ester monomer is contained as the main component of the structural unit constituting the specific (meth) acrylic copolymer.

-A structural unit derived from a monomer having a carboxy group-
The specific (meth) acrylic copolymer contains a structural unit derived from a monomer having a carboxy group.
The carboxy group of the structural unit derived from the monomer having a carboxy group rapidly undergoes a cross-linking reaction with a metal chelate-based cross-linking agent described later. Further, as described above, the carboxy group of the structural unit derived from the monomer having a carboxy group, which is present near the interface of the pressure-sensitive adhesive layer with the base material, is present near the interface of the base material with the pressure-sensitive adhesive layer. The epoxy group of the resin having an epoxy group reacts at the interface between the base material and the pressure-sensitive adhesive layer.

In the present specification, the “constituent unit derived from a monomer having a carboxy group” means a structural unit formed by addition polymerization of a monomer having a carboxy group.

The type of the monomer having a carboxy group is not particularly limited.
Specific examples of the monomer having a carboxy group include acrylic acid (AA), methacrylic acid (MAA), crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, and ω-carboxy-polycaprolactone. Examples thereof include mono (meth) acrylate (for example, ω-carboxy-polycaprolactone (n≈2) monoacrylate) and succinic acid ester (for example, 2-acryloyloxyethyl-succinic acid).
As the monomer having a carboxy group, for example, acrylic acid (AA) is preferable from the viewpoint of copolymerizability.

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

The content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer is not particularly limited, but for example, with respect to all the structural units of the specific (meth) acrylic copolymer. , 0.5% by mass to 15% by mass, more preferably 0.5% by mass to 13% by mass, further preferably 0.8% by mass to 10% by mass, and 1% by mass. It is particularly preferably% to 10% by mass.
When the content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer is 0.5% by mass or more with respect to all the structural units of the specific (meth) acrylic copolymer. If there is, the cross-linking reaction with the metal chelate-based cross-linking agent described later is made more quickly and sufficiently, the cross-linking density of the pressure-sensitive adhesive layer becomes more moderately high, and the transfer of the polyester-based plasticizer from the base material is promoted. Since it can be further reduced, good adhesive strength is maintained better even after undergoing a process of applying heat, and even after long-term use, adhesive residue on the adherend is less likely to occur during peeling. A sheet can be realized. Further, the content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer is 0.5% by mass with respect to all the structural units of the specific (meth) acrylic copolymer. As described above, at the interface between the base material and the pressure-sensitive adhesive layer, the carboxy group that reacts with the epoxy group in the base material is more sufficiently present, and the adhesion between the base material and the pressure-sensitive adhesive layer is further improved. The adhesive sheet tends to be less likely to leave adhesive residue on the adherend when peeled off even when used for a long period of time.
When the content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer is 15% by mass or less with respect to all the structural units of the specific (meth) acrylic copolymer. Since the cross-linking density of the pressure-sensitive adhesive layer does not become excessively high and the pressure-sensitive adhesive layer exhibits a more appropriate cohesive force, the pressure-sensitive adhesive sheet is less likely to leave adhesive residue on the adherend even after long-term use. Can be realized.

Further, the amount of epoxy functional group of the resin having an epoxy group in the base material with respect to the molar ratio of the carboxy group in the specific (meth) acrylic copolymer [the amount of epoxy functional group of the resin having an epoxy group in the base material / specific The molar ratio of carboxy groups in the (meth) acrylic copolymer] is preferably 0.024 to 7.210, more preferably 0.050 to 5.320, and 0.086 to 3 It is more preferably .429, and particularly preferably 0.086 to 1.538.
When the amount of epoxy functional group of the resin having an epoxy group in the base material / the molar ratio of the carboxy group in the specific (meth) acrylic copolymer is within the above range, the interface between the base material and the pressure-sensitive adhesive layer Since the reaction between the epoxy group in the base material and the carboxy group in the pressure-sensitive adhesive layer becomes more appropriate, the adhesion between the base material and the pressure-sensitive adhesive layer is further improved, and the cross-linking density of the pressure-sensitive adhesive layer becomes excessive. Since the pressure is not increased and the pressure-sensitive adhesive layer exhibits a more appropriate cohesive force, it is possible to realize a pressure-sensitive adhesive sheet in which adhesive residue on the adherend is less likely to occur even when used for a long period of time.

The molar ratio of the carboxy group in the specific (meth) acrylic copolymer is the molar ratio of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer, and the specific (meth) acrylic copolymer. It is calculated from the number of carboxy groups (so-called valence) in the structural unit derived from the monomer having a carboxy group in the acrylic copolymer by the following formula.

Molar ratio of carboxy group in specific (meth) acrylic copolymer = [Content rate of structural unit derived from monomer having carboxy group in specific (meth) acrylic copolymer (unit: mass%) × Number (valence) of carboxy groups in the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic copolymer / single amount having a carboxy group in the specific (meth) acrylic copolymer Body molecular weight (g / mol)]

The "molar ratio of carboxy groups in the specific (meth) acrylic copolymer" in the pressure-sensitive adhesive sheet of the present invention can be confirmed by, for example, the following method.
Only the adhesive layer is peeled off from the adhesive sheet. Next, the soluble component is extracted from the peeled pressure-sensitive adhesive layer by using ethyl acetate as an extraction solvent. By this extraction, an uncrosslinked (meth) acrylic copolymer can be obtained as a soluble component. Next, the acid value of the obtained soluble component is measured by a method according to JIS K5601-21: 1999. From the obtained acid value value, the "molar ratio of carboxy groups in the specific (meth) acrylic copolymer" is obtained by the following formula. The "acid value" means the mass (unit: mg) of potassium hydroxide (KOH) required to neutralize the free acid in 1 g of the resin.

Molar ratio of carboxy group in specific (meth) acrylic copolymer = [Acid value of soluble component of pressure-sensitive adhesive layer (unit: mgKOH / g) x 100] / [56.11 (Molecular weight of potassium hydroxide) × 1000]

Further, the "amount of epoxy functional group of the resin having an epoxy group in the base material" in the pressure-sensitive adhesive sheet of the present invention can be confirmed by, for example, the following method.
The soluble component is extracted from the base material after removing the pressure-sensitive adhesive layer from the pressure-sensitive adhesive sheet by using diethyl ether as an extraction solvent. The epoxy equivalent of the insoluble matter remaining by this extraction is measured by a method according to JIS K7236: 2009. From the obtained value of the epoxy equivalent of the insoluble matter, the "amount of epoxy functional group with respect to the vinyl chloride resin per unit mass" is obtained by the following calculation formula.

Amount of epoxy functional group with respect to vinyl chloride resin per unit mass = 1 / [Epoxy equivalent of insoluble matter (unit: g / eq) x content of vinyl chloride resin in insoluble matter (unit: mass%) / 100]

Regarding the content of the vinyl chloride resin in the insoluble matter, the chlorine content in the insoluble matter was measured by a method according to JIS K7229: 1995, and the value of the chlorine content in the obtained insoluble matter was obtained. Therefore, it is calculated from the following formula.

Content of vinyl chloride resin in insoluble matter = [Chlorine content in insoluble matter (unit: mass%)] x [62.5 (molecular weight of vinyl chloride) / 35.45 (atomic weight of chlorine)]

From the "amount of epoxy functional group with respect to the vinyl chloride resin per unit mass", the "amount of epoxy functional group of the resin having an epoxy group in the base material" with respect to 100 g of the vinyl chloride resin is obtained by the following calculation formula.
Amount of epoxy functional group of resin having epoxy group in base material = Amount of epoxy functional group with respect to vinyl chloride resin per unit mass (unit: mol / g) x 100 (unit: g)

-Other building blocks-
The specific (meth) acrylic copolymer is a structural unit derived from the above-mentioned structural unit, that is, a (meth) acrylic acid alkyl ester monomer, and carboxy within the range in which the effect of the present invention is exhibited. It may contain a structural unit (so-called other structural unit) other than the structural unit derived from the monomer having a group.

Examples of the monomer constituting the other structural unit include (meth) acrylate having an aromatic ring represented by benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate and ethoxyethyl. Alkoxyalkyl (meth) acrylate represented by (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and aromatic monovinyl represented by vinyltoluene, acrylonitrile and methacryl. Examples thereof include vinyl cyanide typified by acrylonitrile, and vinyl esters typified by vinyl acrylate, vinyl acetate, vinyl propionate, and vinyl versatic acid. In addition, various derivatives of these monomers can be mentioned.
Examples of the monomer constituting the other structural unit include a monomer having a hydroxyl group represented by 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

<< Weight average molecular weight of specific (meth) acrylic copolymer >>
The weight average molecular weight of the specific (meth) acrylic copolymer is not particularly limited, but is preferably, for example, 300,000 to 1,500,000, more preferably 350,000 to 1,300,000, and 400,000 to 1,200,000. Is more preferable, and 450,000 to 1,000,000 is particularly preferable.
When the weight average molecular weight of the specific (meth) acrylic copolymer is 300,000 or more, the cohesive force of the pressure-sensitive adhesive layer is not too low and tends to be more appropriate.
When the weight average molecular weight of the specific (meth) acrylic copolymer is 1.5 million or less, the cohesive force of the pressure-sensitive adhesive layer is not too high and tends to be more appropriate.

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

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

The weight average molecular weight of the specific (meth) acrylic copolymer can be adjusted to a desired value by adjusting the polymerization temperature, polymerization time, amount of organic solvent used, type of polymerization initiator, amount of polymerization initiator used, and the like. it can.

<< Content of specific (meth) acrylic copolymer >>
The content of the specific (meth) acrylic copolymer in the pressure-sensitive adhesive composition of the present invention is not particularly limited, but is, for example, 70% by mass to 99.9% by mass with respect to the total solid content in the pressure-sensitive adhesive composition. %, More preferably 80% by mass to 99.9% by mass, further preferably 85% by mass to 99.9% by mass, and 90% by mass to 99.9% by mass. Is particularly preferred.
In the present specification, the "total solid content in the pressure-sensitive adhesive composition" means the total mass of the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition does not contain a solvent, and the pressure-sensitive adhesive composition contains a solvent. When included, it means the mass of the residue obtained by removing the solvent from the pressure-sensitive adhesive composition.

<< Manufacturing method of specific (meth) acrylic copolymer >>
The method for producing the specific (meth) acrylic copolymer is not particularly limited.
The specific (meth) acrylic copolymer is obtained by polymerizing the above-mentioned monomer by a known polymerization method typified by, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a massive polymerization method. Can be manufactured by
As the polymerization method, the solution polymerization method is preferable because the treatment step is relatively simple and can be performed in a short time in preparing the pressure-sensitive adhesive composition of the present invention after production.

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

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

In the production of the specific (meth) acrylic copolymer, it is preferable to use an organic solvent that does not easily cause chain transfer during the polymerization reaction of the aromatic hydrocarbon compound, the ester compound, the ketone compound and the like, and in particular, the specific (meth) acrylic. From the viewpoint of solubility of the system copolymer, ease of polymerization reaction and the like, it is preferable to use ethyl acetate.

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

Examples of the polymerization initiator include organic peroxides and azo compounds used in ordinary solution polymerization.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, and di-2-ethylhexylperoxydi. Carbonate, t-butylperoxypivalate, 2,2-bis (4,5-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,5-di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,5-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,54-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4) Examples include -di-t-butylperoxycyclohexyl) butane and 2,2-bis (4,5-di-t-octylperoxycyclohexyl) butane.
Examples of the azo compound include 2,2'-azobisisobutyronitrile [AIBN], 2,2'-azobis (2,4-dimethylvaleronitrile) [ABVN], and 2,2'-azobis (4-). Methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), and 2,2'-azobis (isobutyric acid) dimethyl.
In the production of the specific (meth) acrylic copolymer, it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and particularly preferably an azo compound.

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

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

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

When a chain transfer agent is used in the production of the specific (meth) acrylic copolymer, the amount of the chain transfer agent used is not particularly limited, and is, for example, the molecular weight of the target specific (meth) acrylic copolymer. It is set as appropriate according to the situation.

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

<< Metal chelate cross-linking agent >>
The pressure-sensitive adhesive composition in the present invention contains 0.1 part by mass to 2.0 parts by mass of a metal chelate-based cross-linking agent with respect to 100 parts by mass of the above-mentioned specific (meth) acrylic copolymer.
A specific amount of the metal chelate-based cross-linking agent with respect to the specific (meth) acrylic copolymer contributes to suppressing the migration of the polyester-based plasticizer contained in the base material to the pressure-sensitive adhesive layer.

In the present specification, the "metal chelate-based cross-linking agent" refers to a metal chelate compound (hereinafter, also simply referred to as "metal chelate compound") that functions as a cross-linking agent.

Examples of the metal chelate compound include aluminum monoacetylacetonate bis (ethylacetoacetate), aluminumtris (ethylacetacetate), and aluminum chelate compounds typified by aluminumtris (acetylacetonate), titanium chelate compounds, and zirconium chelate compounds. Examples thereof include cobalt chelate compounds.
Among these, as the metal chelate compound, an aluminum chelate compound is preferable.

As the metal chelate-based cross-linking agent, a commercially available product can be used.
Examples of commercially available metal chelate-based cross-linking agents include aluminum chelate A [trade name, aluminum tris (acetylacetone), Kawaken Fine Chemicals Co., Ltd.], aluminum chelate D [trade name, aluminum monoacetylacetone bis (trade name, aluminum monoacetylacetone bis). Ethylacetacetate), Kawaken Fine Chemicals Co., Ltd.], and ALCH-TR [trade name, aluminum tris (ethylacetacetate), Kawaken Fine Chemicals Co., Ltd.].

The pressure-sensitive adhesive composition in the present invention may contain only one type of metal chelate-based cross-linking agent, or may contain two or more types.

The content of the metal chelate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is 0.1 part by mass to 2.0 parts by mass with respect to 100 parts by mass of the specific (meth) acrylic copolymer, and is 0.15. It is preferably from parts by mass to 2.0 parts by mass, more preferably from 0.2 parts by mass to 2.0 parts by mass, and even more preferably from 0.2 parts by mass to 1.8 parts by mass. It is particularly preferably 0.2 parts by mass to 1.5 parts by mass.
When the content of the metal chelate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is 0.1 part by mass or more with respect to 100 parts by mass of the specific (meth) acrylic copolymer, the cross-linking reaction is rapid and The cross-linking density of the pressure-sensitive adhesive layer is moderately high, and the transfer of the polyester-based plasticizer from the base material can be reduced, so that good pressure-sensitive adhesive strength is maintained even through the process of applying heat. In addition, it is possible to realize an adhesive sheet in which adhesive residue on the adherend is unlikely to occur at the time of peeling even when used for a long period of time.
When the content of the metal chelate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is 2.0 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic copolymer, the cross-linking density of the pressure-sensitive adhesive layer becomes high. The pressure-sensitive adhesive layer exhibits moderate cohesive force without being excessively high. Further, the carboxy group in the pressure-sensitive adhesive layer does not cross-link with the metal chelate-based cross-linking agent more than necessary, and sufficiently reacts with the epoxy group in the base material to improve the adhesion between the base material and the pressure-sensitive adhesive layer. improves. Therefore, even when used for a long period of time, it is possible to realize an adhesive sheet in which adhesive residue on the adherend is unlikely to occur at the time of peeling.

<< Organic Solvent >>
The pressure-sensitive adhesive composition in the present invention may contain an organic solvent, for example, from the viewpoint of improving coatability.
Examples of the organic solvent include the same organic solvents as those used in the polymerization reaction of the specific (meth) acrylic copolymer described above.

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

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

<< Other ingredients >>
The pressure-sensitive adhesive composition in the present invention may contain components other than the above-mentioned components (so-called other components), if necessary, as long as the effects of the present invention are not impaired.
Other components include polymers other than specific (meth) acrylic copolymers, cross-linking catalysts, antistatic agents, antioxidants, colorants (eg dyes and pigments), light stabilizers (eg UV absorbers). ), Various additives such as antistatic agents.

When the pressure-sensitive adhesive composition in the present invention contains these other components, the content of the other components can be appropriately set within the range in which the effects of the present invention are exhibited.

<Gel fraction after cross-linking>
The gel fraction after cross-linking of the pressure-sensitive adhesive composition in the present invention (so-called gel fraction of the pressure-sensitive adhesive layer) is not particularly limited, but is preferably 40% by mass or more, and is preferably 40% by mass to 90% by mass, for example. %, More preferably 40% by mass to 85% by mass, and particularly preferably 40% by mass to 80% by mass.
When the gel fraction after cross-linking of the pressure-sensitive adhesive composition in the present invention is 40% by mass or more, the cohesive force of the pressure-sensitive adhesive layer becomes appropriate, and even when used for a long period of time, it is applied to the adherend at the time of peeling. It is possible to realize an adhesive sheet in which adhesive residue is less likely to occur.

In the present specification, the "gel fraction after cross-linking of the pressure-sensitive adhesive composition" is the percentage of the solvent-insoluble component measured using ethyl acetate as the extraction solvent. Specifically, the gel fraction after cross-linking of the pressure-sensitive adhesive composition is measured according to the following (1) to (4).
(1) Approximately 0.15 g of the crosslinked pressure-sensitive adhesive composition (that is, the pressure-sensitive adhesive layer) was attached to a 250-mesh wire mesh (100 mm × 100 mm) whose mass was accurately measured with a precision balance, and the gel content leaked. Fold the wire mesh 5 times with the attached adhesive layer inside so that it does not exist, and use it as a sample. After that, 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) The sample is taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. After that, the mass is accurately measured with a precision balance.
(4) Calculate the gel fraction by the following formula.
Gel fraction (unit: mass%) = (ZX) / (YX) x 100
However, X is the mass of the wire net (unit: g), Y is the mass of the wire net to which the adhesive layer is attached before immersion (unit: g), and Z is the mass of the wire net to which the adhesive layer is attached and dried after immersion. (Unit: g).

[Thickness of adhesive layer]
The thickness of the pressure-sensitive adhesive layer in the present invention is not particularly limited and can be appropriately set according to the intended purpose.
The thickness of the pressure-sensitive adhesive layer in the present invention is, for example, preferably 10 μm to 100 μm, more preferably 10 μm to 75 μm, further preferably 10 μm to 50 μm, and particularly preferably 20 μm to 50 μm. ..
In general, the thicker the pressure-sensitive adhesive layer, the more likely it is that adhesive residue will occur. On the other hand, the pressure-sensitive adhesive sheet of the present invention tends to be less likely to leave adhesive residue even when the thickness of the pressure-sensitive adhesive layer is 100 μm, for example.

[Release film]
The pressure-sensitive adhesive sheet of the present invention may have a release film on the surface of the pressure-sensitive adhesive layer opposite to the base material.
The release film is not particularly limited as long as it can be easily peeled from the pressure-sensitive adhesive layer, and examples thereof include a resin film in which at least one surface is easily peeled with a release treatment agent.
Examples of the resin film include a polyester film typified by a polyethylene terephthalate film.
Examples of the peeling treatment agent include a silicone-based peeling treatment agent (for example, silicone), a wax-based peeling treatment agent (for example, paraffin wax), and a fluorine-based peeling treatment agent (for example, a fluorine-based resin).

The thickness of the release film is not particularly limited, and is preferably 100 μm to 300 μm, for example.

In the pressure-sensitive adhesive sheet of the present invention, the release film protects the surface of the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet is put into practical use, and is peeled off during use.

[Other layers]
In addition to the base material, the pressure-sensitive adhesive layer, and the release film which may be provided as needed, the pressure-sensitive adhesive sheet of the present invention is a layer for imparting design (so-called) as long as the effects of the present invention are not impaired. , Decorative layer), a layer for imparting a function (for example, antifouling property) (so-called functional layer) and the like (so-called other layer) may be provided.
The other layers can be appropriately selected depending on the purpose.
In the step of providing such a layer, heat is usually applied in many cases as in the drying step.

[Use of adhesive sheet]
The use of the pressure-sensitive adhesive sheet of the present invention is not particularly limited.
The adhesive sheet of the present invention maintains good adhesive strength even after undergoing a process of applying heat, is less likely to leave adhesive residue on the adherend during peeling even after long-term use, and has heat resistance. And because of its excellent transparency, for example, films for protecting the paint of vehicles (for example, automobiles and motorcycles), trains, agricultural machinery, outboard units, etc. (so-called paint protection films), vehicles (for example, automobiles and motorcycles). It is suitable for applications such as stickers used for motorcycles, various signs installed outdoors, and various signs.
The adhesive sheet of the present invention can be suitably used for a painted surface such as melamine coating, alkyd coating, alkyd melamine coating, acrylic coating, urethane coating, epoxy coating and the like.

[Manufacturing method of adhesive sheet]
The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited.
The pressure-sensitive adhesive sheet of the present invention can be produced, for example, by the following method.
The pressure-sensitive adhesive composition is applied onto the surface of the base material to form a coating film. Then, the formed coating film is dried to obtain an adhesive layer. Next, by laminating the exposed surface of the pressure-sensitive adhesive layer and the surface of the release film, a pressure-sensitive adhesive sheet having a laminated structure of a base material / pressure-sensitive adhesive layer / release film can be manufactured.

As another method, for example, the following method can be mentioned.
The pressure-sensitive adhesive composition is applied onto the surface of the release film to form a coating film. Next, the formed coating film is dried to prepare a film with an adhesive layer. Next, by laminating the surface of the pressure-sensitive adhesive layer of the film with the pressure-sensitive adhesive layer and the surface of the base material, a pressure-sensitive adhesive sheet having a laminated structure of a base material / pressure-sensitive adhesive layer / release film can be produced.

The method of applying the pressure-sensitive adhesive composition on the surface of the base material or the release film is not particularly limited.
Examples of the method for applying the pressure-sensitive adhesive composition include known methods using a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a knife coater, a spray coater, a bar coater, an applicator and the like.
The amount of the pressure-sensitive adhesive composition applied onto the surface of the base material or the release film is appropriately set according to, for example, the thickness of the pressure-sensitive adhesive layer to be formed.

The method for drying the coating film is not particularly limited.
Examples of the method for drying the coating film include methods such as natural drying, heat drying, hot air drying, and vacuum drying.
The drying temperature and drying time of the coating film are not particularly limited, and are appropriately set according to, for example, the thickness of the coating film and the amount of the organic solvent in the coating film.

In the pressure-sensitive adhesive sheet of the present invention, the epoxy group existing near the interface between the base material and the pressure-sensitive adhesive layer and the carboxy group existing near the interface between the base material and the pressure-sensitive adhesive layer are the interface between the base material and the pressure-sensitive adhesive layer. In the production of the pressure-sensitive adhesive sheet, for example, the adhesion between the base material and the pressure-sensitive adhesive layer is not required without corona treatment on the base material surface or provision of an undercoat layer on the base material. Becomes good.

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

[Manufacturing of adhesive sheet]
[Example 1]
1. 1. Preparation of base material Vinyl chloride resin [Product name: Kanevinyl (registered trademark) S1001N, average degree of polymerization: 1050, Kaneka Corporation] Resin having 100 parts by mass and an epoxy group [Product name: Metabrene (registered trademark) P-1901, Epoxy equivalent (catalog value): 170 g / eq, Mitsubishi Chemical Co., Ltd.] 2.0 parts by mass (equivalent to 0.012 mol of epoxy functional group) and polyester plasticizer [Product name: ADEKA Sizer] (Registered trademark) PN-446, adipic acid-based polyester, solid content: 100% by mass, number average molecular weight: 2000, ADEKA Corporation] 40 parts by mass and stabilizer [trade name: ADEKA STAB (registered trademark) AC-258 , Barium / zinc-based (Ba / Zn-based) stabilizer, solid content: 100% by mass, ADEKA Corporation] 2.7 parts by mass, and stabilizer [trade name: ADEKA STAB (registered trademark) CPL-1563, calcium / Zinc-based (Ca / Zn-based) stabilizer, solid content: 100% by mass, ADEKA Corporation] 1.2 parts by mass, and external plasticizer [trade name: AC-6A, polyethylene wax, Honeywell] 0.2 mass The part and 2.0 parts by mass of the internal plasticizer [trade name: Butyl stearate, Kawaken Fine Chemical Co., Ltd.] are mixed using a Henschel mixer [Mitsui Miike Kakoki Co., Ltd.] until the temperature reaches 90 ° C. , A mixture was obtained. Next, the obtained mixture was extruded using a single-screw extruder with a T-die (cylinder diameter: 40 mm, L / D: 28) under the conditions of a cylinder temperature of 140 ° C. to 180 ° C. and a die temperature of 200 ° C. A substrate having a thickness of 150 μm was formed.

2. Preparation of Adhesive Composition 90 parts by mass of n-butyl acrylate (n-BA; acrylic acid alkyl ester monomer), acrylic in a reactor equipped with a stirrer, a reflux condenser, a sequential dropping device, and a thermometer. 10 parts by mass of acid (AA; monomer having a carboxy group) and 75 parts by mass of ethyl acetate were added and mixed to obtain a mixture, and then the inside of the reactor was substituted with nitrogen. Then, the mixture in the reactor was heated to 70 ° C. with stirring, and then 2,2'-azobis (2,4-dimethylvaleronitrile) [ABVN; polymerization initiator] 0.02 in 120 parts by mass of ethyl acetate. The solution in which the mass part was dissolved was sequentially added dropwise over 4 hours, and the reaction was carried out for 2 hours after the completion of the addition. After completion of the reaction, the reaction mixture was diluted with ethyl acetate to obtain a solution of a (meth) acrylic copolymer having a solid content concentration of 30% by mass. The "solid content concentration" here means the mass ratio of the (meth) acrylic copolymer to the solution of the (meth) acrylic copolymer.
Next, 100 parts by mass (solid content conversion value) of the solution of the (meth) acrylic copolymer and 0.25 parts by mass (solid) of the metal chelate-based cross-linking agent [trade name: aluminum chelate A, Kawaken Fine Chemical Co., Ltd.] (Minute conversion value) and was sufficiently mixed to obtain a pressure-sensitive adhesive composition.

3. 3. Manufacture of Adhesive Sheet The adhesive composition prepared above is applied onto the surface of a release film [trade name: PET75GS, Lintec Corporation] using an applicator so that the thickness after drying is 30 μm. , A coating film was formed. Next, the formed coating film was dried at 100 ° C. for 90 seconds using a hot air circulation type dryer to obtain an adhesive layer on the release film.
Next, the exposed surface of the pressure-sensitive adhesive layer is laminated on the surface of the base material produced above, and then pressure-bonded using a hand roller to laminate the base material / pressure-sensitive adhesive layer / release film. An adhesive sheet having a structure was obtained.

[Examples 2 to 5, and 18]
In Examples 2 to 5, and Example 18, the same operations as in Example 1 were performed except that the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer was changed to the composition shown in Table 1. This was done to obtain an adhesive sheet.

[Examples 6 to 10, Example 15, and Example 16]
In Examples 6 to 10, Examples 15, and Example 16, the components other than the stabilizer, the external lubricant, and the internal lubricant among the raw materials for producing the base material were changed to the compositions shown in Table 1. Except for the above, the same operation as in Example 2 was carried out to obtain an adhesive sheet.

[Examples 11 to 14]
Examples 11 to 14 are the same as in Example 1 except that the components other than the stabilizer, the external lubricant, and the internal lubricant among the raw materials for producing the base material are changed to the compositions shown in Table 1. To obtain an adhesive sheet.

[Example 17 and Example 19]
In Examples 17 and 19, the same as in Example 18 except that the components other than the stabilizer, the external lubricant, and the internal lubricant among the raw materials for producing the base material were changed to the compositions shown in Table 1. To obtain an adhesive sheet.

[Comparative Example 1, Comparative Example 2, and Comparative Example 8 to 11]
In Comparative Example 1, Comparative Example 2, and Comparative Examples 8 to 11, the composition of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer was changed to the composition shown in Table 2, except that the composition was changed to that of Example 1. The same operation was performed to obtain an adhesive sheet.

[Comparative Examples 3 to 7]
Comparative Examples 3 to 7 are the same as in Example 2 except that the components other than the stabilizer, the external lubricant, and the internal lubricant among the raw materials for producing the base material are changed to the compositions shown in Table 2. To obtain an adhesive sheet.

The weight average molecular weight of the (meth) acrylic copolymer in Examples 1 to 19, Comparative Example 1, and Comparative Examples 3 to 11 is 600,000, and the (meth) acrylic copolymer in Comparative Example 2 is used. The weight average molecular weight of the polymer was 500,000.
The weight average molecular weight of the (meth) acrylic copolymer was measured by the same method as the above-mentioned method for measuring the weight average molecular weight of the specific (meth) acrylic copolymer.

Epoxy in the substrate with respect to the molar ratio of carboxy groups in the (meth) acrylic copolymer in the pressure-sensitive adhesive sheets of Examples 1 to 19, Comparative Example 1, Comparative Example 2 and Comparative Examples 4 to 9. Tables 1 and 2 show the amount of epoxy functional groups of the resin having a group [the amount of epoxy functional groups of the resin having an epoxy group in the base material / the molar ratio of carboxy groups in the (meth) acrylic copolymer]. ..
The amount of epoxy functional group / molar ratio of carboxy group in the (meth) acrylic copolymer of the resin having an epoxy group in the base material was calculated by the method described above. Hereinafter, as an example, the calculation method for the adhesive sheet of Example 1 will be shown.

Mol ratio of carboxy group in (meth) acrylic copolymer = [Content rate of structural unit derived from monomer having carboxy group in (meth) acrylic copolymer (unit: mass%) × (meth) ) Number of carboxy groups in the structural unit derived from the monomer having a carboxy group in the acrylic copolymer (valence) / Molecular weight of the monomer having a carboxy group in the (meth) acrylic copolymer ( g / mol)]
= [10 (parts by mass) / 100 (parts by mass) x 100 (%) / 1 x 72.1 (g / mol)]
= 0.13869 ... ≒ 0.1387

Amount of epoxy functional group of resin having epoxy group in base material / molar ratio of carboxy group in (meth) acrylic copolymer = 0.012 / 0.1387
= 0.0865 ・ ・ ・ ≒ 0.0865

In Tables 1 and 2, "Amount of epoxy functional groups of the resin having an epoxy group in the base material with respect to the molar ratio of carboxy groups in the (meth) acrylic copolymer [resin having an epoxy group in the base material". Amount of epoxy functional group / molar ratio of carboxy group in (meth) acrylic copolymer] ”was described as“ amount of epoxy functional group / molar ratio of carboxy group ”.

Details of each component contained in the base materials shown in Tables 1 and 2 are as shown below.
<Vinyl chloride resin>
"Kaneka Vinyl S1001N" [Product name, average degree of polymerization: 1050, Kaneka Corporation]
The above "Kane Vinyl" is a registered trademark.

<Compound with epoxy group>
(resin)
"Metabrene P-1901" [Product name, weight average molecular weight: 68000, epoxy equivalent (catalog value): 170 g / eq, acrylic resin, Mitsubishi Chemical Corporation]
"Marproof G-01100" [Product name, weight average molecular weight: 12000, epoxy equivalent (catalog value): 170 g / eq, acrylic resin, NOF CORPORATION]
"Marproof G-0150M" [Product name, weight average molecular weight: 10000, epoxy equivalent (catalog value): 310 g / eq, acrylic resin, NOF CORPORATION]
"Marproof G-0130SP" [Product name, weight average molecular weight: 9000, epoxy equivalent (catalog value): 530 g / eq, acrylic resin, NOF CORPORATION]
The above-mentioned "Metabrene" and the above-mentioned "Marproof" are both registered trademarks.
(Other than resin)
"Epoxyd soybean oil" [Product name: New Sizar 510R, Molecular weight: 946, NOF Corporation]
The above "New Sizar" is a registered trademark.

<Plasticizer>
(Polyester plasticizer)
"ADEKA SIZER PN-446" [trade name, adipic acid polyester, solid content: 100% by mass, number average molecular weight: 2000, ADEKA Corporation]
"ADEKA SIZER PN-150" [trade name, adipic acid polyester, solid content: 100% by mass, number average molecular weight: 1000, ADEKA Corporation]
"ADEKA SIZER PN-350" [trade name, adipic acid polyester, solid content: 100% by mass, number average molecular weight: 3000, ADEKA Corporation]
The above "Adeka Sizar" is a registered trademark.
(Other plasticizers)
"DOP" [trade name, bis (2-ethylhexyl) phthalate, J-Plus Co., Ltd.]

Details of each of the monomers shown in Tables 1 and 2 are as shown below.
"N-BA": n-butyl acrylate "2EHA": 2-ethylhexyl acrylate "MA": methyl acrylate "2HEA": 2-hydroxyethyl acrylate "AA": acrylic acid

Details of the cross-linking agents shown in Tables 1 and 2 are as shown below.
<Crosslinking agent>
(Metal chelate cross-linking agent)
"Aluminum chelate A" [Product name, Kawaken Fine Chemical Co., Ltd.]
(Other cross-linking agents)
"TETRAD-C" [Product name, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy-based cross-linking agent, solid content: 100% by mass, Mitsubishi Gas Chemical Company, Inc.]
"Coronate L-45E" [trade name, adduct of toluene diisocyanate (TDI) and trimethylolpropane (TMP), isocyanate-based cross-linking agent, solid content: 45% by mass, Tosoh Corporation]
"Duranate E405-80T" [trade name, hexamethylene diisocyanate (HMDI), isocyanate-based cross-linking agent, solid content: 80% by mass, Asahi Kasei Corporation]
The above "TETRAD", "Coronate", and "Duranate" are all registered trademarks.

<Crosslink catalyst>
"ADEKA STUB OT-1" [Product name, Dioctyl tin dilaurate, ADEKA Corporation]]
The above "Adecastab" is a registered trademark.

In Tables 1 and 2, "-" means that there is no corresponding item in that column.
In Tables 1 and 2, the numerical values described in the column of "blending amount" are all solid content conversion values, and are shown for each base material and each pressure-sensitive adhesive composition.

[Measurement and evaluation]
1. 1. Measurement of gel fraction For each pressure-sensitive adhesive layer in Example 1 and Example 2, the gel fraction was measured according to the following (1) to (4).

(1) Approximately 0.15 g of an adhesive layer is attached to a 250 mesh wire mesh (100 mm x 100 mm) whose mass is accurately measured with a precision balance, and the attached adhesive layer is placed inside so that the gel does not leak. Then, the wire mesh is folded 5 times and used as a sample. After that, 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) The sample is taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. After that, the mass is accurately measured with a precision balance.
(4) Calculate the gel fraction by the following formula.
Gel fraction (unit: mass%) = (ZX) / (YX) x 100
However, X is the mass of the wire net (unit: g), Y is the mass of the wire net to which the adhesive layer is attached before immersion (unit: g), and Z is the mass of the wire net to which the adhesive layer is attached and dried after immersion. (Unit: g).

As a result, the gel fraction of the pressure-sensitive adhesive layer in Example 1 was 55% by mass, and the gel fraction of the pressure-sensitive adhesive layer in Example 2 was 65% by mass.

2. Adhesive Strength Maintenance Rate The adhesive strength maintenance rate was evaluated for each of the adhesive sheets of Examples 1 to 19, Comparative Examples 1 to 9, and Comparative Example 11. The pressure-sensitive adhesive sheet of Comparative Example 10 was not evaluated because it was confirmed that the cross-linking reaction had not progressed.
First, the adhesive sheet was cut into a size of 25 mm × 150 mm, and six evaluation adhesive sheet pieces were prepared. Of the six evaluation adhesive sheet pieces prepared, three were used for the initial measurement of the adhesive strength, and the remaining three were used for the measurement of the adhesive strength after the heat treatment.

(1) Initial Adhesive Strength Under an environment of an atmospheric temperature of 23 ° C. and 50% RH, the release film was peeled off from the three evaluation adhesive sheet pieces, and the surfaces of the adhesive layer exposed by the peeling were made of different stainless steels. A laminated body was produced by laminating and adhering to the surface of a plate (SUS plate) [trade name: SUS304 (BA), Partec Co., Ltd.], and then reciprocating and crimping a 2 kg rubber roller once. The produced laminate has a laminated structure of an adhesive film piece (base material / adhesive layer) / SUS plate. Next, the prepared laminate was allowed to stand in an environment of an atmospheric temperature of 23 ° C. and 50% RH for 24 hours to prepare three test pieces.
For the three test pieces, the adhesive strength (unit: N / 25 mm) when the adhesive film piece (base material / adhesive layer) is peeled 180 ° in the long side (150 mm) direction from the SUS plate is a single column type material. The measurement was carried out using a testing machine [model number: STA-1225, A & D Co., Ltd.] under the condition of an ambient temperature of 23 ° C. and a peeling speed of 300 mm / min in an environment of 50% RH. After arithmetically averaging the measured values, the second digit after the decimal point was rounded off, and the obtained value was used as the initial adhesive strength for evaluation. The results are shown in Tables 3 and 4.

(2) Adhesive strength after heat treatment Three evaluation adhesive sheet pieces were allowed to stand in a constant temperature bath set at 50 ° C. for 72 hours. Next, the release film was peeled off from the three evaluation adhesive sheet pieces after standing in an environment of an atmospheric temperature of 23 ° C. and 50% RH, and the surfaces of the adhesive layer exposed by the peeling were separated from each other by a stainless steel plate. A laminated body was produced by laminating and laminating on the surface of (SUS plate) [trade name: SUS304 (BA), Partec Co., Ltd.], and then reciprocating and crimping a 2 kg rubber roller once. The produced laminate has a laminated structure of an adhesive film piece (base material / adhesive layer) / SUS plate. Next, the obtained laminate was allowed to stand in an environment of an atmospheric temperature of 23 ° C. and 50% RH for 24 hours to prepare three test pieces.
For the three test pieces, the adhesive strength (unit: N / 25 mm) when the adhesive film piece (base material / adhesive layer) is peeled 180 ° in the long side (150 mm) direction from the SUS plate is a single column type material. The measurement was carried out using a testing machine [model number: STA-1225, A & D Co., Ltd.] under the condition of an ambient temperature of 23 ° C. and a peeling speed of 300 mm / min in an environment of 50% RH. The measured values were arithmetically averaged and then rounded to the second decimal place. Then, the obtained value was used as the adhesive strength after the heat treatment and used for evaluation. The results are shown in Tables 3 and 4.

(3) Calculation of maintenance rate The maintenance rate (unit:%) of the adhesive force was calculated from the initial adhesive force and the adhesive force after the heat treatment based on the following formula. The calculated value was rounded off to the first decimal place and used to evaluate the maintenance rate of adhesive strength.
Adhesive strength maintenance rate (unit:%) = [adhesive strength after heat treatment (unit: N / 25 mm) / initial adhesive strength (unit: N / 25 mm)] x 100

The evaluation criteria are as follows.
If the evaluation result is "A" or "B", it is judged that there is no practical problem.
The results are shown in Tables 3 and 4.

-Evaluation criteria-
A: The maintenance rate of adhesive strength is 70% or more.
B: The maintenance rate of adhesive strength is 50% or more and less than 70%.
C: The maintenance rate of adhesive strength is less than 50%.

3. 3. Adhesive residue Each of the pressure-sensitive adhesive sheets of Examples 1 to 19, Comparative Examples 1 to 9, and Comparative Example 11 was evaluated for adhesive residue after long-term use. The pressure-sensitive adhesive sheet of Comparative Example 10 was not evaluated because it was confirmed that the cross-linking reaction had not progressed.
First, a heating acceleration test was conducted to evaluate the adhesive residue of the pressure-sensitive adhesive sheet used for a long period of time.
The adhesive sheet was cut into a size of 25 mm × 150 mm, and three pieces of the adhesive sheet for evaluation were prepared. Next, in an environment of an ambient temperature of 23 ° C. and 50% RH, the release film was peeled off from the three evaluation adhesive sheet pieces, and the surfaces of the adhesive layer exposed by the peeling were separated from each other by a separate alkyd melamine white coating plate ( Hereinafter, a laminated body was produced by laminating and adhering them on the surface of a "painted plate"), and then reciprocating a 2 kg rubber roller once and crimping the film. The produced laminated body has a laminated structure of an adhesive film piece (base material / adhesive layer) / coated plate. Next, the prepared laminate was allowed to stand in a constant temperature bath set at 80 ° C. for 168 hours, and then allowed to stand in an environment with an ambient temperature of 23 ° C. and 50% RH for 24 hours to prepare three test pieces. ..
Three test pieces after the heating acceleration test were peeled off in an environment of an ambient temperature of 23 ° C. and 50% RH using a single column type material tester [model number: STA-1225, A & D Co., Ltd.]. The adhesive film piece (base material / adhesive layer) was peeled 180 ° in the long side (150 mm) direction from the coated plate under the condition of a speed of 300 mm / min, and the surface of the coated plate after the peeling was visually observed.

The evaluation criteria are as follows.
If the evaluation result is "A" or "B", it is judged that there is no practical problem.
The results are shown in Tables 3 and 4.

-Evaluation criteria-
A: In all three test pieces, no adhesive residue was confirmed on the surface of the coated plate.
B: In any of the three test pieces, adhesive residue was confirmed on a part of the surface of the coated plate.
C: In any of the three test pieces, adhesive residue was confirmed on the entire surface of the coated plate.

4. Heat resistance Each of the pressure-sensitive adhesive sheets of Examples 1 to 19 and Comparative Examples 1 to 11 was evaluated for heat resistance.
The adhesive sheet was cut into a size of 25 mm × 150 mm, and three pieces of the adhesive sheet for evaluation were prepared. The three pieces of the prepared adhesive sheet for evaluation were allowed to stand in a gear oven set at 200 ° C. Then, the evaluation adhesive sheet pieces left in the gear oven are visually observed every 10 minutes, and at least one of the three evaluation adhesive sheet pieces is yellowed. The time until confirmation was measured. Then, the obtained value was used as the time until yellowing, and was used for the evaluation of heat resistance.

The evaluation criteria are as follows.
If the evaluation result is "A" or "B", it is judged that there is no practical problem.
The results are shown in Tables 3 and 4.

-Evaluation criteria-
A: It takes 100 minutes or more to turn yellow.
B: The time until yellowing is 50 minutes or more and less than 100 minutes.
C: The time until yellowing is less than 50 minutes.

5. Transparency The transparency of each of the pressure-sensitive adhesive sheets of Examples 1 to 19 and Comparative Examples 1 to 11 was evaluated.
The adhesive sheet was cut into a size of 25 mm × 150 mm, and three pieces of the adhesive sheet for evaluation were prepared. The release film was peeled off from the three evaluation adhesive sheet pieces prepared, and the haze (unit:%) was measured using a haze meter [model number: NDH 5000SP, Nippon Denshoku Kogyo Co., Ltd.]. The measured values were arithmetically averaged and then rounded to the second decimal place. Then, the obtained value was used for the evaluation of transparency.

The evaluation criteria are as follows.
If the evaluation result is "A" or "B", it is judged that there is no practical problem.
The results are shown in Tables 3 and 4.

-Evaluation criteria-
A: The haze is less than 3.0%.
B: The haze is 3.0% or more and less than 5.0%.
C: Haze is 5.0% or more.

In Table 4, "-" means that the measurement and evaluation corresponding to that column were not performed.

As shown in Table 3, it was confirmed that the pressure-sensitive adhesive sheets of Examples 1 to 19 maintained good adhesive strength even after the heat treatment. Further, it was confirmed that the adhesive sheets of Examples 1 to 19 are less likely to leave adhesive residue on the adherend even when used for a long period of time. Further, it was confirmed that the pressure-sensitive adhesive sheets of Examples 1 to 19 were excellent in heat resistance and transparency.

On the other hand, as shown in Table 4, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 having a pressure-sensitive adhesive layer formed by using a cross-linking agent other than the metal chelate-based cross-linking agent have significantly reduced adhesive strength after heat treatment. It was confirmed that the adhesive strength before the heat treatment could not be maintained well.
It was confirmed that the pressure-sensitive adhesive sheet of Comparative Example 3 provided with a resin-free base material having an epoxy group tends to leave adhesive residue on the adherend when peeled off after long-term use. Further, it was confirmed that the pressure-sensitive adhesive sheet of Comparative Example 3 was inferior in heat resistance to the pressure-sensitive adhesive sheet of Example.
It was confirmed that the pressure-sensitive adhesive sheet of Comparative Example 4 provided with the base material containing no polyester-based plasticizer had a significantly reduced adhesive strength after the heat treatment, and the adhesive strength before the heat treatment could not be maintained satisfactorily.
The pressure-resistant adhesive sheet of Comparative Example 5 including a base material having an epoxy functional group amount of less than 0.005 mol with respect to 100 parts by mass of the vinyl chloride resin has heat resistance as compared with the pressure-sensitive adhesive sheet of Examples. It was confirmed that the sex was inferior.
The pressure-sensitive adhesive sheet of Comparative Example 6 having a substrate having an epoxy functional group amount of more than 0.05 mol with respect to 100 parts by mass of the vinyl chloride resin was more transparent than the pressure-sensitive adhesive sheet of Example. Was confirmed to be inferior.
It was confirmed that the pressure-sensitive adhesive sheet of Comparative Example 7 provided with a base material containing epoxidized soybean oil instead of the resin having an epoxy group had a significantly reduced adhesive strength after the heat treatment, and the adhesive strength before the heat treatment could not be maintained satisfactorily. It was.
The pressure-sensitive adhesive sheet of Comparative Example 8 comprising a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition in which the content of the metal chelate-based cross-linking agent with respect to 100 parts by mass of the (meth) acrylic copolymer is less than 0.1 parts by mass is It was confirmed that the adhesive strength was remarkably reduced after the heat treatment, and the adhesive strength before the heat treatment could not be maintained well. Further, it was confirmed that when the adhesive sheet of Comparative Example 8 was used for a long period of time, adhesive residue on the adherend was likely to occur at the time of peeling. It is presumed that the reason why the adhesive residue is likely to occur in the pressure-sensitive adhesive sheet of Comparative Example 8 is that the cross-linking of the pressure-sensitive adhesive layer is insufficient and the cohesive force of the pressure-sensitive adhesive layer is reduced by long-term use.
The pressure-sensitive adhesive sheet of Comparative Example 9 comprising a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition in which the content of the metal chelate-based cross-linking agent with respect to 100 parts by mass of the (meth) acrylic copolymer exceeds 2.0 parts by mass is It was confirmed that when used for a long period of time, adhesive residue on the adherend is likely to occur during peeling. In the pressure-sensitive adhesive sheet of Comparative Example 9, the reason why adhesive residue is likely to occur is that the amount of the metal chelate-based cross-linking agent is too large, and the carboxy group of the constituent unit derived from the monomer having a carboxy group is the metal chelate-based cross-linking agent. Because the cross-linking reaction occurs more than necessary, the number of carboxy groups that react with the epoxy groups in the base material at the interface between the base material and the pressure-sensitive adhesive layer decreases, and sufficient adhesion between the base material and the pressure-sensitive adhesive layer cannot be obtained. It is presumed.
Adhesion of Comparative Example 10 comprising a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer containing no structural unit derived from a monomer having a carboxy group and a metal chelate-based cross-linking agent. The sheet did not undergo cross-linking, and the adhesive strength and adhesive residue could not be evaluated.
Comparative Example 11 comprising a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer containing no structural unit derived from a monomer having a carboxy group, an isocyanate-based cross-linking agent, and a cross-linking catalyst. It was confirmed that the adhesive strength of the adhesive sheet of No. 1 was significantly reduced after the heat treatment, and the adhesive strength before the heat treatment could not be maintained well.

Claims (8)

A base material and an adhesive layer arranged on the base material are provided.
The base material contains a vinyl chloride resin, a resin having an epoxy group, and a polyester plastic agent, and the amount of the epoxy functional group of the resin having an epoxy group with respect to 100 parts by mass of the vinyl chloride resin is 0. It is a base material of 005 mol to 0.05 mol, and is
The pressure-sensitive adhesive layer includes a (meth) acrylic copolymer containing a structural unit derived from a (meth) acrylic acid alkyl ester monomer and a structural unit derived from a monomer having a carboxy group, and the (meth). A pressure-sensitive adhesive sheet, which is a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing 0.1 parts by mass to 2.0 parts by mass of a metal chelate-based cross-linking agent with respect to 100 parts by mass of an acrylic copolymer. The content of the structural unit derived from the monomer having a carboxy group in the (meth) acrylic copolymer is 0.5% by mass or more based on all the structural units of the (meth) acrylic copolymer. The adhesive sheet according to claim 1, which is 15% by mass. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the content of the polyester-based plasticizer in the base material is 15 parts by mass to 65 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the resin having an epoxy group has a weight average molecular weight of 5,000 to 100,000. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the resin having an epoxy group is an acrylic resin. Claims 1 to 7.210, wherein the amount of the epoxy functional group of the resin having the epoxy group in the base material with respect to the molar ratio of the carboxy group in the (meth) acrylic copolymer is 0.024 to 7.210. The adhesive sheet according to any one of 5. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the thickness of the base material is 50 μm to 300 μm. The adhesive sheet according to any one of claims 1 to 7, wherein the adherend surface is a painted surface of a vehicle.