WO2021261585A1

WO2021261585A1 - Adhesive composition for decorative film, and use thereof

Info

Publication number: WO2021261585A1
Application number: PCT/JP2021/024138
Authority: WO
Inventors: 祐介橋本; 伸幸竹谷; 聡子安藤; 絵美子時田
Original assignee: 東亞合成株式会社
Priority date: 2020-06-26
Filing date: 2021-06-25
Publication date: 2021-12-30
Also published as: TW202200648A; JP2022007594A

Abstract

An adhesive composition for a decorative film contains a block copolymer having a polymer block (A) and a (meth)acrylic polymer block (B), and a vinyl polymer (C). The vinyl polymer (C) has a glass transition temperature of 30 to 200°C inclusive and a number average molecular weight of 500 to 10,000 inclusive. In the adhesive composition for a decorative film, the content of the vinyl polymer (C) is 0.5 to 60 mass parts inclusive per 100 mass parts of the block copolymer.

Description

Adhesive composition for decorative films and its uses

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2020-110666 filed on June 26, 2020, and the contents of the description are incorporated herein by reference.

The present disclosure relates to an adhesive composition for a decorative film and its use.

For the purpose of improving design and measures against VOC (Volatile Organic Compounds), decorative films are attached or transferred to molded products, mainly for automobile interior / exterior parts and home appliances. As a molding method using a decorative film, in-mold molding by injection molding, vacuum forming, vacuum pressure forming, and the like are used. Further, as a decorative film to be bonded to a molded product, a decorative film provided with an adhesive layer is known.

When giving a design to a molded product with a decorative film, attention is being paid to a technique of stretching the decorative film and attaching it to the molded product. The decorative film attached to the molded product in the stretched state is liable to be displaced from the molded product, peeled off, or floated under high temperature conditions, which may cause an appearance defect. Especially in the field of automobiles, a product to which a decorative film is bonded may be required to have heat resistance in an environment exceeding 100 ° C., and various decorative films have been proposed to meet this requirement (for example,). See Patent Document 1).

In Patent Document 1, a vinyl polymer having a glass transition temperature of 30 ° C. or higher and 200 ° C. or lower and a number average molecular weight of 500 or higher and 10,000 or lower is randomly copolymerized with a (meth) acrylic monomer. It is disclosed that a pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive polymer is used to form a pressure-sensitive adhesive layer of a decorative film. Further, Patent Document 1 describes a pressure-sensitive adhesive layer that exhibits high adhesiveness even under high temperature conditions by keeping the glass transition temperature of the entire pressure-sensitive adhesive layer and the surface layer portion and the storage elastic modulus at 90 ° C. within a predetermined range. It is disclosed that you will get.

Japanese Unexamined Patent Publication No. 2019-11254

In order to increase the heat resistance of the pressure-sensitive adhesive layer, it is conceivable to increase the molecular weight of the acrylic pressure-sensitive adhesive polymer constituting the pressure-sensitive adhesive layer. However, when the acrylic adhesive polymer has a high molecular weight, the viscosity of the pressure-sensitive adhesive composition increases, and the coatability decreases due to the high viscosity, or it becomes necessary to dilute to a viscosity suitable for coating. There is a concern that the handleability may be reduced. Further, when the pressure-sensitive adhesive composition is diluted to ensure the coatability of the pressure-sensitive adhesive composition, the coating film thickness becomes thick, and the pressure-sensitive adhesive performance is deteriorated by the components remaining in the pressure-sensitive adhesive layer due to insufficient drying. It is also conceivable that foaming may occur during drying, resulting in poor appearance. On the other hand, if the acrylic adhesive polymer has a low molecular weight in order to reduce the viscosity of the pressure-sensitive adhesive composition, the heat resistance of the pressure-sensitive adhesive layer is lowered.

Also, in the automobile field, etc., products that have been given a design by a decorative film are expected to be used in a harsh environment where temperature changes are drastic. In such a usage environment, there is a concern that the adhesive layer may be peeled off from the molded product or floated due to repeated shrinkage and expansion of the base material layer of the decorative film due to changes in the ambient temperature. For this reason, the adhesive layer of the decorative film has high adhesiveness and heat resistance under high temperature conditions, and is highly durable because it is less likely to be displaced, peeled off, or floated from the molded product due to temperature changes. Is required.

The present disclosure has been made in view of the above problems, and it is possible to form an adhesive layer having high adhesiveness under high temperature conditions and high heat resistance and durability against temperature changes while reducing the viscosity. The main purpose is to provide a possible pressure-sensitive adhesive composition.

The present inventors have diligently studied in order to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by using a pressure-sensitive adhesive composition having a specific composition. This disclosure has been completed based on these findings. According to the present disclosure, the following means are provided.

[1] A block copolymer having a polymer block (A) and a (meth) acrylic polymer block (B) and a vinyl polymer (C) are contained, and the vinyl polymer (C) is The glass transition temperature is 30 ° C. or higher and 200 ° C. or lower, the number average molecular weight is 500 or higher and 10,000 or lower, and the content of the vinyl polymer (C) is 100 parts by mass of the block polymer. A pressure-sensitive adhesive composition for a decorative film, which is 0.5 parts by mass or more and 60 parts by mass or less.

[2] The polymer block (A) is a polymer having a glass transition temperature of 100 ° C. or higher, and the (meth) acrylic polymer block (B) has a glass transition temperature of −50 ° C. or higher to −10 ° C. The pressure-sensitive adhesive composition for a decorative film according to the above [1], which is the following polymer.
[3] The polymer block (A) contains at least one selected from the group consisting of a structural unit derived from an aromatic vinyl compound and a structural unit derived from an imide group-containing vinyl compound. [2] Adhesive composition for decorative film.
[4] The pressure-sensitive adhesive composition for a decorative film according to any one of the above [1] to [3], wherein the block copolymer has a weight average molecular weight of 200,000 or more and 700,000 or less.
[5] Any of the above [1] to [4], wherein the block copolymer has a molecular weight distribution (Mw / Mn) of 3.5 or less represented by the ratio of the weight average molecular weight to the number average molecular weight. Adhesive composition for decorative films.

[6] The pressure-sensitive adhesive composition for a decorative film according to any one of the above [1] to [5], which further contains a cross-linking agent.
[7] The vinyl polymer (C) has a glass transition temperature of 40 ° C. or higher and 140 ° C. or lower, and a number average molecular weight of 1,000 or more and 9,500 or lower. Adhesive composition for any of the decorative films.
[8] Any of the above [1] to [7], wherein the content of the vinyl polymer (C) is 0.5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the block copolymer. Adhesive composition for decorative films.

[9] In the (meth) acrylic polymer block (B), the structural unit derived from the (meth) acrylic acid alkoxy ester compound is used as the total monomer unit of the (meth) acrylic polymer block (B). The pressure-sensitive adhesive composition for a decorative film according to any one of the above [1] to [8], which contains 20% by mass or more and 99% by mass or less with respect to the above.
[10] A decorative film comprising an adhesive layer comprising the adhesive composition for a decorative film according to any one of the above [1] to [9].
[11] A decorative molded body to which the decorative film of the above [10] is attached to the molded body.

According to the pressure-sensitive adhesive composition for decorative films of the present disclosure, it is possible to obtain a pressure-sensitive adhesive layer having high adhesiveness under high temperature conditions, heat resistance and durability against temperature changes while reducing the viscosity. can.

Hereinafter, this disclosure will be described in detail. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacrylic, and "(meth) acrylate" means acrylate and / or methacrylate. Further, the “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.

<< Adhesive composition for decorative film >>
The pressure-sensitive adhesive composition for a decorative film of the present disclosure (hereinafter, also referred to as "the present pressure-sensitive adhesive composition") is a pressure-sensitive adhesive composition used as a pressure-sensitive adhesive for adhering or transferring a decorative film to a molded body. Is. The present pressure-sensitive adhesive composition comprises a block copolymer having a polymer block (A) and a (meth) acrylic polymer block (B) (hereinafter, also referred to as “block copolymer (P)”) and a vinyl weight. Contains the coalescence (C). Hereinafter, the block copolymer (P) and the vinyl polymer (C) to be blended in the pressure-sensitive adhesive composition, and the components to be blended as necessary will be described in detail.

<Block Copolymer (P)>
The polymer block (A) and the (meth) acrylic polymer block (B) contained in the block copolymer (P) are segments having different monomer compositions from each other. In the block copolymer (P), the polymer block (A) is preferably a segment having a higher glass transition temperature (Tg) than the (meth) acrylic polymer block (B).

In the present specification, the Tg of the polymer is a value measured by differential scanning calorimetry (DSC). The details of the measurement method follow the operations described in Examples described later. The Tg of each polymer block is a value obtained by producing a polymer corresponding to the polymer block to be measured and obtaining the Tg of the produced polymer by DSC. The Tg of the polymer can be arbitrarily selected by changing the type and composition of the constituent monomers.

(Polymer block (A))
The polymer block (A) can be obtained by polymerizing a vinyl monomer. The polymer block (A) is a structural unit and an imide group derived from an aromatic vinyl compound in that it can form a polymer block having a sufficiently high Tg and can impart excellent heat resistance to the block copolymer (P). It is preferable to contain at least one selected from the group consisting of structural units derived from the contained vinyl compound (hereinafter, also referred to as “structural unit U1”).

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene and p-ethyl. Styrene, pn-butyl styrene, p-isobutyl styrene, pt-butyl styrene, o-methoxy styrene, m-methoxy styrene, p-methoxy styrene, o-chloro styrene, m-chloro styrene, p-chloro styrene , P-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol, o-vinyl benzoic acid, m-vinyl benzoic acid, p-vinyl benzoic acid Examples thereof include styrene-based compounds such as acid and divinylbenzene, and vinylnaphthalene. Of these, the aromatic vinyl compound is preferably a styrene compound. As the aromatic vinyl compound, one or more of these can be used.

Examples of the imide group-containing vinyl compound include maleimide compounds such as maleimide and N-substituted maleimide compounds; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-2-ethylhexylitaconimide, and N-cyclohexyl. Itaconimide compounds such as itaconimide; citraconimide compounds such as N-methylcitraconimide, N-ethylcitraconimide, N-butylcitraconimide, N-2-ethylhexylcitraconimide, and N-cyclohexylcitraconimide; N- (2- (2- (Meta) acryloyloxyethyl) succinate imide, N- (2- (meth) acryloyloxyethyl) maleimide, N- (2- (meth) acryloyloxyethyl) phthalate imide, and N- (4- (meth) Examples thereof include (meth) acrylicimide compounds such as acryloyloxybutyl) phthalateimide. Of these, maleimide compounds are preferable because they exhibit high copolymerizability with styrene-based compounds.

As the maleimide compound, a maleimide and an N-substituted maleimide compound can be preferably used. Examples of the N-substituted maleimide compound include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, and N. -N-alkyl substituted maleimide compounds such as pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, and N-stearylmaleimide; N such as N-cyclopentylmaleimide and N-cyclohexylmaleimide. -Cycloalkyl-substituted maleimide compounds; N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide; N-phenylmaleimide, N- (4-hydroxyphenyl) maleimide, N- (4-acetylphenyl) maleimide, N- (4-) Examples thereof include N-aryl substituted maleimide compounds such as methoxyphenyl) maleimide, N- (4-ethoxyphenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromophenyl) maleimide. As the imide group-containing vinyl compound, one or more of these can be used.

Among the above, the imide group-containing vinyl compound used for producing the block copolymer (P) is described below in that the heat resistance and adhesiveness of the block copolymer (P) can be further improved. The compound represented by the formula (1) is preferable.

(In the formula (1), R ¹ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group, or a hydroxy group at an arbitrary position of the phenyl group, an alkoxy group having 1 to 2 carbon atoms, and acetyl. Represents a substituted phenyl group to which a group or a halogen atom is bonded.)

When an aromatic vinyl compound is used in the production of the polymer block (A), the ratio of the structural units derived from the aromatic vinyl compound to all the monomer units of the polymer block (A) improves the cohesive force. From the viewpoint and from the viewpoint of increasing the Tg of the polymer block (A), 1% by mass or more is preferable, 5% by mass or more is more preferable, 10% by mass or more is further preferable, and 20% by mass or more is further preferable. Regarding the upper limit of the ratio of the structural unit derived from the aromatic vinyl compound, it is preferably 90% by mass or less, more preferably 80% by mass or less, and 70% by mass, based on all the monomer units of the polymer block (A). The following is even more preferable, and 50% by mass or less is even more preferable.

When an imide group-containing vinyl compound is used in the production of the polymer block (A), the ratio of the structural units derived from the imide group-containing vinyl compound to the total monomer units of the polymer block (A) is the same as that of the block. From the viewpoint of sufficiently increasing the heat resistance of the polymer (P), 5% by mass or more is preferable, 10% by mass or more is more preferable, 20% by mass or more is further preferable, and 30% by mass or more is further preferable. The upper limit of the ratio of the structural unit derived from the imide group-containing vinyl compound is preferably 95% by mass or less, more preferably 90% by mass or less, and more preferably 80% by mass, based on all the monomer units of the polymer block (A). % Or less is more preferable. When the ratio of the imide group-containing vinyl compound is 95% by mass or less, the adhesiveness of the block copolymer (P) can be sufficiently ensured, which is preferable.

Styrene compounds tend to improve the polymerizable properties of maleimide compounds. Therefore, when a maleimide compound is used as the monomer unit constituting the polymer block (A), it is preferable to improve the polymerizable property of the maleimide compound by using a styrene compound in combination. When the imide group-containing vinyl compound and the styrene-based compound are used in combination in the production of the polymer block (A), the styrene-based compound is used in the polymer block (A) with respect to 1 mol of the structural unit derived from the imide group-containing vinyl compound. The ratio of the derived structural unit is preferably 0.01 to 100 mol, more preferably 0.1 to 10 mol, still more preferably 0.2 to 5 mol, still more preferably 0.5 to 1.5 mol. be.

The ratio of the structural unit U1 in the polymer block (A) is preferably 30% by mass or more, more preferably 50% by mass or more, and more preferably 60% by mass or more, based on the total monomer units of the polymer block (A). Is even more preferable, and 70% by mass or more is even more preferable.

In the production of the polymer block (A), the polymer block (A) is crosslinked by using a vinyl monomer having a crosslinkable functional group (hereinafter, also referred to as “crosslinkable group-containing monomer”). The structure may have a sex structural unit. Since the polymer block (A) has a crosslinkable structural unit, the pressure-sensitive adhesive layer formed by using the present pressure-sensitive adhesive composition has adhesiveness under high temperature conditions, heat resistance, and durability against temperature changes (cold-heat cycle). It is preferable in that the characteristics) can be further improved. The crosslinkable group-containing monomer is not particularly limited, and examples thereof include unsaturated carboxylic acid, unsaturated acid anhydride, hydroxy group-containing vinyl compound, epoxy group-containing vinyl compound, and reactive silicon group-containing vinyl compound. Be done.

Specific examples of the crosslinkable group-containing monomer include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamon acid, and monoalkyl of unsaturated dicarboxylic acid as unsaturated carboxylic acids. Esters (monoalkyl esters such as maleic acid, fumaric acid, itaconic acid, citraconic acid) and the like; as unsaturated acid anhydrides, for example, maleic anhydride, itaconic acid anhydride, citraconic acid anhydride and the like;
As hydroxy group-containing vinyl compounds, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth) (Meta) hydroxyalkyl compounds of (meth) acrylate, such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate and polyethylene glycol-polypropylene glycol mono ( Polyalkylene glycol mono (meth) acrylate compounds such as meta) acrylates, unsaturated alcohols such as allyl alcohol, N-substituted maleimide compounds such as N- (4-hydroxyphenyl) maleimide, and o-hydroxystyrene and m-hydroxystyrene. And hydroxyl group-containing styrene compounds such as p-hydroxystyrene;
Examples of the epoxy group-containing vinyl compound include epoxy group-containing (meth) acrylic acid ester compounds such as glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth) acrylate. ;
As the reactive silicon group-containing vinyl compound, a vinyl silane compound such as vinyl trimethoxysilane, vinyl tritoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane; trimethoxysilylpropyl (meth) acrylate, triethoxy (meth) acrylate. Cyril group-containing (meth) acrylic acid ester compounds such as silylpropyl, methyldimethoxysilylpropyl (meth) acrylate and dimethylmethoxysilylpropyl (meth) acrylate, silyl group-containing vinyl ether compounds such as trimethoxysilylpropyl vinyl ether, and tri. Examples thereof include silyl group-containing vinyl ester compounds such as methoxysilyl undecanoate vinyl and the like. Further, as the crosslinkable group-containing monomer, an oxazoline group-containing vinyl compound, an isocyanate group-containing vinyl compound, or the like may be used. In the production of the polymer block (A), one kind or two or more kinds can be used as the crosslinkable group-containing monomer.

When the polymer block (A) has a crosslinkable structural unit, the crosslinkable structural unit is preferably a structural unit derived from the (meth) acrylic monomer among the above. Among these, the crosslinkable structural unit is a group consisting of (meth) acrylic acid, (meth) acrylic acid hydroxyalkyl compound, epoxy group-containing (meth) acrylic acid ester compound, and silyl group-containing (meth) acrylic acid ester compound. It is preferably a structural unit derived from at least one monomer selected from, and particularly preferably a structural unit derived from a (meth) hydroxyalkyl acrylate compound. As the (meth) hydroxyalkyl acrylate compound, a compound having a hydroxyalkyl group having 2 to 8 carbon atoms is preferable, and a compound having a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable, from the viewpoint of adhesive performance.

When the polymer block (A) has a crosslinkable structural unit, the content of the crosslinkable structural unit is preferably 1% by mass or more, more preferably 1% by mass, based on all the monomer units of the polymer block (A). It is preferably 5% by mass or more, and more preferably 10% by mass or more. When the proportion of the crosslinkable structural unit in the polymer block (A) is 1% by mass or more, the crosslinkable structure is sufficiently formed by the polymer block (A), and the block has good heat resistance and durability against temperature changes. It becomes easy to obtain the polymer (P). The upper limit of the content of the crosslinkable structural unit is not particularly limited, but from the viewpoint of maintaining a high Tg of the polymer block (A), the content of the polymer block (A) is relative to all the monomer units. It is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.

The polymer block (A) is a monomer copolymerizable with at least one of an aromatic vinyl compound and an imide group-containing vinyl compound as long as the action of the block copolymer (P) is not impaired, and is aromatic. It may further contain a structural unit derived from a polymer different from the vinyl compound and the imide group-containing vinyl compound (hereinafter, also referred to as “other monomer A”). Examples of the other monomer A include the compound exemplified as the crosslinkable group-containing monomer, an alkyl (meth) acrylic acid compound, an aliphatic cyclic ester compound of (meth) acrylic acid, and (meth) acrylic. Acid alkenyl ester compound, (meth) acrylic acid aromatic ester compound, aliphatic vinyl compound, amino group-containing vinyl compound, amide group-containing vinyl compound, polyfunctional (meth) acrylate compound, polyfunctional alkenyl compound, nitrile group-containing Examples thereof include unsaturated compounds and dialkyl ester compounds of unsaturated dicarboxylic acids. Specific examples of these compounds include the compounds exemplified in the description of the (meth) acrylic polymer block (B) and the vinyl polymer (C) described later. As the other monomer A, only one kind may be used, or two or more kinds may be used.

In the production of the polymer block (A), the amount of the other monomer A used can be appropriately set within a range that does not impair the effects of the present disclosure. The ratio of the structural units derived from the other monomer A to the total monomer units of the polymer block (A) is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferable. Is 30% by mass or less.

The Tg of the polymer block (A) is preferably 100 ° C. or higher. When the Tg of the polymer block (A) is 100 ° C. or higher, the effect of improving the cohesive force due to the pseudo-crosslinking formed by the microphase separation structure of the block copolymer (P) can be maintained even at a high temperature. Adhesion, heat resistance and durability against temperature changes can be imparted. From this point of view, the Tg of the polymer block (A) is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, still more preferably 160 ° C. or higher, still more preferably 180 ° C. or higher, and more preferably 180 ° C. or higher. Particularly preferably, it is 200 ° C. or higher. The Tg of the polymer block (A) is 350 ° C. or lower in that the degree of freedom of the constituent monomer units that can be used is high and that the heating temperature at the time of bonding can be suppressed from becoming too high. It is preferably 280 ° C. or lower, more preferably 270 ° C. or lower, and even more preferably 260 ° C. or lower.

The number average molecular weight (Mn) of the polymer block (A) is preferably in the range of 1,000 to 45,000. When Mn is 1,000 or more, the cohesive force of the block copolymer (P) can be sufficiently secured, and when it is 45,000 or less, the flexibility is maintained and the peel strength with respect to the adherend is increased. It is preferable in that it can be sufficiently high. The Mn of the polymer block (A) is preferably 2,000 or more, more preferably 3,000 or more, still more preferably 5,000 or more, still more preferably 7,000 or more. The upper limit of Mn of the polymer block (A) is preferably 40,000 or less, more preferably 35,000 or less, still more preferably 33,000 or less, still more preferably 30,000 or less. Is. In addition, in this specification, Mw and Mn of a polymer are standard polystyrene conversion values obtained by using gel permeation chromatography (GPC).

The weight average molecular weight (Mw) of the polymer block (A) is preferably in the range of 1,000 to 50,000. The Mw of the polymer block (A) is preferably 2,000 or more, more preferably 3,000 or more, still more preferably 6,000 or more, still more preferably 9,000 or more. The upper limit of Mw of the polymer block (A) is preferably 48,000 or less, more preferably 45,000 or less, still more preferably 40,000 or less, still more preferably 35,000 or less. Is.

When a plurality of polymer blocks (A) are present in one molecule of the block copolymer (P), what are "Mn of the polymer block (A)" and "Mw of the polymer block (A)"? , Mn and Mw of the entire plurality of polymer blocks (A) possessed by one molecule of the block copolymer (P). For example, when the block copolymer (P) is a (ABA) type triblock composed of a polymer block (A) / (meth) acrylic polymer block (B) / polymer block (A). The Mn of the polymer block (A) in the triblock is a value obtained by adding the Mns of the two polymer blocks (A).

((Meta) Acrylic Polymer Block (B))
The (meth) acrylic polymer block (B) is a polymer containing a (meth) acrylic monomer as a main monomer unit. As the monomer constituting the (meth) acrylic polymer block (B), the (meth) acrylic acid alkyl compound and the (meth) acrylic acid alkyl compound and the polymer block having a relatively low Tg and sufficient adhesiveness can be obtained. At least one monomer selected from the group consisting of (meth) acrylic acid alkoxy ester compounds (hereinafter, also referred to as “structural unit U2”) can be preferably used. As the monomer constituting the (meth) acrylic polymer block (B), one type may be used alone or two or more types may be used in combination.

The (meth) acrylic acid alkyl compound used for producing the (meth) acrylic polymer block (B) is a (meth) acrylic acid alkyl compound having an alkyl group having 1 to 10 carbon atoms in the alkyl ester moiety (-COOR). Is preferable. Specific examples thereof include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and (meth) acrylic acid. Isobutyl, (meth) acrylic acid n-hexyl, (meth) acrylic acid n-octyl, (meth) acrylic acid isooctyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid n-nonyl, (meth) acrylic acid Examples thereof include isononyl, n-decyl (meth) acrylate, and lauryl (meth) acrylate. Of these, preferred monomers include n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, and n (meth) acrylate. -Nonyl, isononyl (meth) acrylate and the like can be mentioned.

The (meth) acrylic acid alkoxyester compound used for producing the (meth) acrylic polymer block (B) is preferably a (meth) acrylic acid alkoxyalkyl compound having an alkoxyalkyl group having 2 to 12 carbon atoms. Specific examples include methoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, butoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include butoxyethyl, methoxybutyl (meth) acrylate, ethoxybutyl (meth) acrylate, butoxybutyl (meth) acrylate and the like.

In the (meth) acrylic polymer block (B), the content of the structural unit U2 is preferably 50% by mass or more with respect to all the monomer units of the (meth) acrylic polymerizable block (B). 70% by mass or more is more preferable, 80% by mass or more is further preferable, and 90% by mass or more is further preferable. By setting the ratio of the structural unit U2 to 30% by mass or more, the adhesive strength, initial adhesive strength (tack), low temperature adhesiveness, and the like of the obtained pressure-sensitive adhesive composition can be sufficiently increased. The upper limit of the content of the structural unit U2 is not particularly limited. The range of the content of the structural unit U2 is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass, based on all the monomer units of the (meth) acrylic polymer block (B). % Or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less.

In the (meth) acrylic polymer block (B), in particular, the vinyl polymer (C) tends to segregate on the surface layer in the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive composition is adhered under high and low temperature conditions while keeping the viscosity low. It is preferable to include a structural unit derived from the (meth) acrylic acid alkoxyester compound in that the property, heat resistance and durability against temperature changes can be improved. Specifically, the content of the structural unit derived from the (meth) acrylic acid alkoxy ester compound is 20% by mass or more with respect to the total monomer unit of the (meth) acrylic polymer block (B). It is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more. The upper limit of the content of the structural unit derived from the (meth) acrylic acid alkoxy ester compound is not particularly limited, but from the viewpoint of sufficiently ensuring compatibility with the vinyl polymer (C) and high-temperature adhesiveness, (meth) acrylic. It is preferably 99% by mass or less, more preferably 90% by mass or less, based on all the monomer units of the system polymer block (B). The range of the content of the structural unit derived from the (meth) acrylic acid alkoxy ester compound is preferably 20% by mass or more and 99% by mass or less, and more preferably 30% by mass or more and 95% by mass or less.

The (meth) acrylic polymer block (B) has 1 to 3 carbon atoms in the alkyl ester portion in that the vinyl polymer (C) easily segregates to the surface layer in the pressure-sensitive adhesive layer and further enhances heat resistance. It can also contain structural units derived from (meth) alkyl acrylate compounds having an alkyl group. By using such an alkyl (meth) acrylate compound in the production of the (meth) acrylic polymer block (B), the elastic modulus of the (meth) acrylic polymer block (B) can be increased. Effective for improving heat resistance. Among these, one selected from the group consisting of methyl (meth) acrylate and ethyl (meth) acrylate is preferable, and methyl (meth) acrylate is more preferable. In the (meth) acrylic polymer block (B), the content of the structural unit derived from the (meth) acrylic acid ester having an alkyl group having 1 to 3 carbon atoms is from the viewpoint of ensuring the flexibility of the adhesive coating film. , 70% by mass or less, more preferably 40% by mass or less.

In the production of the (meth) acrylic polymer block (B), it is possible to use a compound which is a monomer unit of a homopolymer having a dissolution parameter (SP value) of 9.9 or more obtained by the Fedors method. The vinyl polymer (C) is likely to segregate on the surface layer portion of the pressure-sensitive adhesive layer, which is preferable. Examples of the monomer having an SP value of 9.9 or more in the homopolymer include methyl (meth) acrylate, ethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, and 2-ethoxyethyl (meth) acrylate. Examples thereof include hydroxyethyl, acryloylmorpholine, (meth) acrylic acid, styrene, and benzyl methacrylate. The (meth) acrylic polymer block (B) has a structural unit derived from such a monomer, preferably 15 mass by mass with respect to all the monomer units of the (meth) acrylic polymer block (B). % Or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, still more preferably 50% by mass or more.

By using a crosslinkable group-containing monomer in the production of the (meth) acrylic polymer block (B), the (meth) acrylic polymer block (B) has a structure having a crosslinkable structural unit. be able to. Since the (meth) acrylic polymer block (B) has a crosslinkable structural unit, it is preferable in that the adhesiveness, heat resistance and durability of the pressure-sensitive adhesive layer under high temperature conditions can be further improved. When the block copolymer (P) has a crosslinkable structural unit, only one of the polymer block (A) and the (meth) acrylic polymer block (B) has a crosslinkable structural unit. Also, both the polymer block (A) and the (meth) acrylic polymer block (B) may have a crosslinkable structural unit.

The crosslinkable group-containing monomer used for producing the (meth) acrylic polymer block (B) is not particularly limited, but contains (meth) acrylic acid, a (meth) hydroxyalkyl compound acrylate, and an epoxy group (meth). It is preferably at least one selected from the group consisting of an acrylic acid ester compound and a silyl group-containing (meth) acrylic acid ester compound. Among these, the (meth) acrylic acid hydroxyalkyl compound is preferable because the adhesive strength of the (meth) acrylic polymer block (B) tends to be high, and it has a hydroxyalkyl group having 2 to 8 carbon atoms. Compounds are more preferable, and compounds having a hydroxyalkyl group having 2 to 4 carbon atoms are particularly preferable. Specific examples of the (meth) acrylic acid hydroxyalkyl compound, the epoxy group-containing (meth) acrylic acid ester compound, and the silyl group-containing (meth) acrylic acid ester compound are exemplified in the description of the polymer block (A). Examples include compounds.

When the (meth) acrylic polymer block (B) has a crosslinkable structural unit, the content of the crosslinkable structural unit is relative to all the monomer units of the (meth) acrylic polymer block (B). It is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more. By setting the content of the crosslinkable structural unit in the (meth) acrylic polymer block (B) to 0.1% by mass or more, a good crosslinked structure is formed, and both the blocks exhibiting higher heat resistance and durability. The polymer (P) can be obtained. The upper limit of the content of the crosslinkable structural unit is not particularly limited, but from the viewpoint of increasing the flexibility of the obtained pressure-sensitive adhesive layer, all the monomers of the (meth) acrylic polymer block (B) It is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and particularly preferably 10% by mass or less with respect to the unit. In the production of the (meth) acrylic polymer block (B), only one type of crosslinkable-containing monomer may be used, or two or more types may be used.

In addition to the above, the (meth) acrylic polymer block (B) is a monomer copolymerizable with the above-mentioned monomer (hereinafter, “other monomer B”” as long as the adhesive performance is not impaired. Also called) may be used. Examples of the other monomer B include an aliphatic cyclic ester compound of (meth) acrylic acid, an aromatic ester compound of (meth) acrylic acid, an aromatic vinyl compound, an imide group-containing vinyl compound, and an amino group-free compound. Examples thereof include saturated compounds, amide group-containing unsaturated compounds, cyano group-containing unsaturated compounds, and nitrile group-containing unsaturated compounds. Specific examples of these compounds include the compounds exemplified above and the compounds exemplified in the description of the vinyl polymer (C) described later. The other monomer B may be used alone or in combination of two or more.

In the production of the (meth) acrylic polymer block (B), the amount of the other monomer B used can be appropriately set within a range that does not impair the effects of the present disclosure. The ratio of the structural units derived from the other monomer B to the total monomer units of the (meth) acrylic polymer block (B) is preferably 20% by mass or less, more preferably 10% by mass or less. It is more preferably 5% by mass or less.

The Tg of the (meth) acrylic polymer block (B) is preferably in the range of −50 ° C. or higher and −10 ° C. or lower. When the Tg of the polymer block (B) is −50 ° C. or higher, the cohesive force of the pressure-sensitive adhesive layer obtained by the present pressure-sensitive adhesive composition can be sufficiently increased, and the adhesiveness tends to be sufficiently ensured. When Tg is −10 ° C. or lower, sufficient adhesiveness and curved surface followability under low temperature conditions can be ensured. Further, even when the molded body to which the decorative film is bonded is used in an environment in which the base material layer of the decorative film thermally expands and contracts, the adhesive layer has good followability to the base material layer. , A decorative film having high durability against temperature changes can be obtained. The Tg of the (meth) acrylic polymer block (B) is more preferably −45 ° C. or higher. The upper limit of Tg is more preferably −15 ° C., and even more preferably −20 ° C. The range of Tg of the (meth) acrylic polymer block (B) is more preferably −50 ° C. or higher and −15 ° C. or lower, and further preferably −45 ° C. or higher and −20 ° C. or lower.

The polymer block (A) may have a property of phase separation from the (meth) acrylic polymer block (B). Having such a property is preferable in that the block copolymer (P) can easily form a microphase-separated structure. A person skilled in the art can easily design a polymer block (A) that is phase-separated from the (meth) acrylic polymer block (B) based on the common general knowledge as of the filing of the present application. For example, when the SP value of the polymer block (A) calculated by a method for calculating the SP value, which is a known solubility parameter (for example, the Fedors method), is compared with the SP value of the (meth) acrylic polymer block (B). The difference ΔSP (absolute value) of is 0.01 or more. The difference ΔSP may be, for example, 0.05 or more, for example 0.1 or more, for example 0.2 or more, or for example 0.5 or more. In the case of the Fedors method, the SP value is R.I. F. It can be calculated by the calculation method described in "Polymer Engineering and Science" 14 (2) and 147 (1974) written by Fedors. In addition, the SP value can be easily estimated for the phase separation between blocks by observing the intended structure of the block copolymer (P) with an electron microscope, a scanning probe microscope, small-angle X-ray scattering, or the like. can.

As long as the block copolymer (P) has the polymer block (A) and the (meth) acrylic polymer block (B), the number of blocks and the arrangement are not particularly limited. Specific examples of the block copolymer (P) include a (AB) type diblock composed of a polymer block (A) and a (meth) acrylic polymer block (B), and a polymer block (A). / (ABA) type triblock composed of (meth) acrylic polymer block (B) / polymer block (A), and (meth) acrylic polymer block (B) / polymer block (A) / Examples thereof include a (BAB) type triblock body composed of a (meth) acrylic polymer block (B). Further, the block copolymer (P) may further have a polymer block other than the polymer block (A) and the (meth) acrylic polymer block (B). Of these, the block copolymer (P) preferably has a (ABA) type structure. With such a structure, the polymer block (A) and the (meth) acrylic polymer block (B) can easily form a pseudo-crosslinked structure, and the heat resistance and durability against temperature changes are improved as well as the adhesive physical properties.

The ratio of the polymer block (A) to the (meth) acrylic polymer block (B) in the block copolymer (P) (hereinafter, also referred to as “block ratio”) is the polymer block (A) / (meth). ) When represented by the acrylic polymer block (B), the mass ratio is preferably 1/99 to 20/80. When the block ratio is within the above range, the block copolymer having a polymer block (A) that can form a hard segment and can be a cross-linking point and a (meth) acrylic polymer block (B) that can be a soft segment can be used. It is possible to obtain a pressure-sensitive adhesive composition having excellent heat resistance and durability while keeping the viscosity of the pressure-sensitive adhesive composition low. Further, it is possible to form a pressure-sensitive adhesive layer having excellent followability to thermal expansion of the base material layer, and it is possible to obtain a pressure-sensitive adhesive layer that is unlikely to peel off or float from the molded body even under high temperature conditions. From this point of view, the block ratio is more preferably 1/99 to 13/87, still more preferably 1/99 to 10/90, still more preferably 1/99 to 7/93, and even more. It is preferably 3/97 to 7/93.

The Mw of the block copolymer (P) is from the viewpoint of exhibiting sufficient cohesive force and good adhesiveness, and from the viewpoint of sufficiently segregating the vinyl polymer (C) on the surface layer portion of the pressure-sensitive adhesive layer. , 200,000 or more is preferable. When the Mw of the block copolymer (P) is 200,000 or more, sufficient adhesiveness can be ensured, heat resistance can be sufficiently increased, and floating and peeling of the pressure-sensitive adhesive layer due to temperature changes are sufficiently suppressed. can do. The Mw of the block copolymer (P) is more preferably 230,000 or more, further preferably 250,000 or more, still more preferably 260,000 or more, and particularly preferably 280,000 or more. be.

On the other hand, if Mw is too large, the viscosity of the pressure-sensitive adhesive composition becomes too high, which may lead to deterioration in coatability and handleability, or may make it difficult to handle in manufacturing. Therefore, the Mw of the block copolymer (P) is preferably 700,000 or less, more preferably 650,000 or less, further preferably 600,000 or less, and 550,000 or less. Is even more preferable. The range of Mw of the block copolymer (P) is preferably 200,000 or more and 700,000 or less, more preferably 230,000 or more and 650,000 or less, and further preferably 250,000 or more and 600,000 or less. It is as follows.

The Mn of the block copolymer (P) is preferably 100,000 or more, more preferably 120,000 or more, still more preferably 130,000 or more, from the viewpoint of exhibiting good adhesiveness and sufficient cohesive force. , 150,000 or more are even more preferable. The upper limit of Mn of the block copolymer (P) is preferably 500,000 or less, more preferably 400,000 or less, from the viewpoint of ease of production and good compatibility with the vinyl polymer (C). 300,000 or less is more preferable, and 200,000 or less is even more preferable. The range of Mn of the block copolymer (P) is preferably 100,000 or more and 500,000 or less, and more preferably 120,000 or more and 400,000 or less.

For the block copolymer (P), the molecular weight distribution (Mw / Mn) expressed by the ratio of Mw and Mn makes it easy to obtain good adhesive strength and suppresses the increase in viscosity of the pressure-sensitive adhesive composition. From the point of view, 4.5 or less is preferable, 3.5 or less is more preferable, 3.3 or less is further preferable, 3.0 or less is further preferable, and 2.8 or less is particularly preferable. The lower limit of Mw / Mn of the block copolymer (P) is not particularly limited and may be 1.0 or more.

<Manufacturing method of block copolymer (P)>
The block copolymer (P) is not particularly limited in the production method as long as a polymer having the polymer block (A) and the (meth) acrylic polymer block (B) can be obtained. It can be obtained by a known production method. Examples of the method for producing the block copolymer (P) include a method using various controlled polymerization methods such as living radical polymerization and living anionic polymerization, and a method of coupling polymers having functional groups with each other. .. Among these, the living radical polymerization method is preferable because it is easy to operate and can be applied to a wide range of monomers.

For living radical polymerization, any process such as batch process, semi-batch process, dry continuous polymerization process, continuous stirring tank type process (CSPR) may be adopted. Further, the polymerization type can be applied to various aspects such as bulk polymerization using no solvent, solvent-based solution polymerization, aqueous emulsion polymerization, mini-emulsion polymerization or suspension polymerization.

There are no particular restrictions on the type of living radical polymerization method, such as reversible addition-cleaving chain transfer polymerization method (RAFT method), nitroxy radical method (NMP method), atom transfer radical polymerization method (ATRP method), and organic tellurium compounds. Various polymerization methods such as a polymerization method using (TERP method), a polymerization method using an organic antimony compound (SBRP method), a polymerization method using an organic bismuth compound (BIRP method), and an iodine transfer polymerization method can be adopted. Among these, the RAFT method, the NMP method and the ATRP method are preferable from the viewpoint of controllability of polymerization and ease of implementation.

In the RAFT method, controlled polymerization proceeds via a reversible chain transfer reaction in the presence of a specific polymerization control agent (RAFT agent) and a general free radical polymerization initiator. As the RAFT agent, various known RAFT agents such as a dithioester compound, a zantate compound, a trithiocarbonate compound and a dithiocarbamate compound can be used. As the RAFT agent, a monofunctional compound having only one active site may be used, or a bifunctional or higher functional compound may be used. It is preferable to use a bifunctional RAFT agent from the viewpoint that it is easy to efficiently obtain a block copolymer having 3 or more blocks. The amount of the RAFT agent used is appropriately adjusted depending on the monomer used, the type of the RAFT agent, and the like.

As the polymerization initiator used in the polymerization by the RAFT method, known radical polymerization initiators such as azo compounds, organic peroxides and persulfates can be used, but they are easy to handle for safety and are used during radical polymerization. Azo compounds are preferable because side reactions are unlikely to occur. Specific examples of the azo compound include 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2, 4-Dimethylvaleronitrile), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1- Carbonitrile), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide) and the like. As the polymerization initiator, only one type may be used, or two or more types may be used in combination. The proportion of the polymerization initiator used is not particularly limited, but the amount of the polymerization initiator used is 0. 1 per mol of the RAFT agent from the viewpoint of stably performing the polymerization reaction and obtaining a polymer having a smaller molecular weight distribution. It is preferably 01 mol or more and 0.5 mol or less, and more preferably 0.01 mol or more and 0.2 mol or less.

The reaction temperature during the polymerization reaction by the RAFT method is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 45 ° C. or higher and 90 ° C. or lower, and further preferably 50 ° C. or higher and 80 ° C. or lower. When the reaction temperature is 40 ° C. or higher, the polymerization reaction can proceed smoothly, which is preferable. Further, when the reaction temperature is 100 ° C. or lower, side reactions can be suppressed and restrictions on the initiators and solvents that can be used are relaxed, which is preferable.

In the NMP method, a specific alkoxyamine compound or the like having nitroxide is used as a living radical polymerization initiator, and the polymerization is allowed to proceed via the nitroxide radical derived from the living radical polymerization initiator. In the production of the block copolymer (P), the type of nitroxide radical is not particularly limited, and a commercially available nitroxide-based polymerization initiator can be used. From the viewpoint of polymerization controllability when polymerizing a monomer containing an acrylate, it is preferable to use a compound represented by the following formula (2) as the nitroxide compound.

(In the formula (2), R ¹ is an alkyl group or a hydrogen atom ^{having 1 to 2 carbon atoms, R 2} is an alkyl group or a nitrile group having 1 to 2 carbon ^{atoms, and R 3} is − (CH ₂ ) m. -., m is an integer of 0 to 2, R ⁴ and R ⁵ are each independently an alkyl group having 1 to 4 carbon atoms plurality of R ⁴ in formula are be the same or different from each other at best, a plurality of R ⁵ in the formula may be the same or different from each other.)

The nitroxide compound represented by the above formula (2) undergoes a primary dissociation by heating at about 70 to 80 ° C. and causes an addition reaction with a vinyl-based monomer. At this time, it is possible to obtain a polyfunctional polymerization precursor by adding a nitroxide compound to a vinyl-based monomer having two or more vinyl groups. Next, the vinyl-based monomer can be subjected to living polymerization by secondary dissociation of the polymerization precursor under heating. In this case, since the polymerization precursor has two or more active sites in the molecule, a polymer having a narrower molecular weight distribution can be obtained. From the viewpoint of efficiently obtaining the block copolymer (P), it is preferable to use a bifunctional polymerization precursor having two active sites in the molecule. The amount of the nitroxide compound used is appropriately adjusted depending on the monomer used, the type of the nitroxide compound, and the like.

When the block copolymer (P) is produced by the NMP method, 0.001 to 0.2 of the nitroxide radical represented by the following formula (3) is added to 1 mol of the nitroxide compound represented by the above formula (2). Polymerization may be carried out by adding in the range of moles.

(In the formula (3), R ⁶ and R ⁷ are independently alkyl groups having 1 to 4 carbon atoms. A plurality of R 6s in the formula may be the same or different from each other ^{, and a plurality of R 6 in the formula may be different from each other.} R ⁷ may be the same or different from each other.)

By adding 0.001 mol or more of the nitroxide radical represented by the above formula (3), the time for the concentration of the nitroxide radical to reach a steady state can be shortened. This is preferable in that the polymerization can be controlled to a higher degree and a polymer having a narrower molecular weight distribution can be obtained. On the other hand, if the amount of nitroxide radical added is too large, the polymerization may not proceed. A more preferable amount of the nitroxide radical added to 1 mol of the nitroxide compound is in the range of 0.01 to 0.5 mol, and a more preferable amount of addition is in the range of 0.05 to 0.2 mol.

The reaction temperature in the NMP method is preferably 50 ° C. or higher and 140 ° C. or lower, more preferably 60 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. or higher and 120 ° C. or lower. When the reaction temperature is 50 ° C. or higher, the polymerization reaction can proceed smoothly. On the other hand, if the reaction temperature is 140 ° C. or lower, side reactions such as radical chain transfer tend to be suppressed.

In the ATRP method, an organic halide is generally used as an initiator, and a transition metal complex is used as a catalyst to carry out a polymerization reaction. The organic halide used as an initiator may be a monofunctional compound or a bifunctional or higher functional compound. It is preferable to use a bifunctional compound in that the block copolymer (P) can be easily obtained efficiently. As the type of halogen, bromide and chloride are preferable. The reaction temperature in the ATRP method is preferably 20 ° C. or higher and 200 ° C. or lower, and more preferably 50 ° C. or higher and 150 ° C. or lower. When the reaction temperature is 20 ° C. or higher, the polymerization reaction can proceed smoothly, which is preferable.

When an ABA triblock copolymer composed of a polymer block (A) / (meth) acrylic polymer block (B) / polymer block (A) is obtained by the living radical polymerization method, each block is sequentially polymerized. You may obtain the block copolymer of interest. In this case, first, as the first polymerization step, the constituent monomers of the polymer block (A) are polymerized to obtain the polymer block (A). Next, as a second polymerization step, the constituent monomers of the (meth) acrylic polymer block (B) are polymerized to obtain a (meth) acrylic polymer block (B). Further, as a third polymerization step, the constituent monomers of the polymer block (A) are polymerized. Thereby, (ABA) type triblock copolymer can be obtained. As the polymerization initiator, it is preferable to use the above-mentioned monofunctional polymerization initiator or polymerization precursor.

Further, when an ABA triblock copolymer is produced by a two-step polymerization step shown below using a bifunctional polymerization initiator or a polymerization precursor, the desired product can be obtained more efficiently. First, as a first polymerization step, the constituent monomers of the polymer block (A) are polymerized to obtain a polymer block (A), and then as a second polymerization step, a (meth) acrylic polymer block (B). ) Is polymerized. Thereby, (ABA) type triblock copolymer can be obtained. According to this method, the process can be simplified as compared with the case where each block is sequentially polymerized and manufactured.

The block copolymer (P) may be polymerized in the presence of a chain transfer agent, if necessary. As the chain transfer agent, known ones can be used. Specifically, ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 2-butanethiol, 1-hexanethiol, 2-hexanethiol, 2-butylbutane-1-thiol, 1,1- In addition to alkylthiol compounds having an alkyl group having 2 to 20 carbon atoms such as dimethyl-1-pentanethiol, 1-dodecanethiol, tert-tetradecanethiol, 1-hexadecanethiol and 1-octadecanethiol, mercaptoacetic acid and mercaptopropionic acid. , 2-Mercaptoethanol and the like. As the chain transfer agent, one or more of these can be used.

In the production of the block copolymer (P), a known polymerization solvent can be used in living radical polymerization. Specifically, aromatic compounds such as benzene, toluene, xylene and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, dimethylsulfoxide, Examples include alcohol and water. Further, it may be carried out in the form of bulk polymerization or the like without using a polymerization solvent.

<Vinyl polymer (C)>
The vinyl polymer (C) is a polymer having a glass transition temperature (Tg) of 30 ° C. or higher and 200 ° C. or lower. When the Tg of the vinyl polymer (C) is less than 30 ° C., when the pressure-sensitive adhesive layer is formed by the present pressure-sensitive adhesive composition, the Tg of the surface layer portion of the pressure-sensitive adhesive layer is unlikely to be sufficiently high, and under high temperature conditions. Adhesive strength and heat resistance cannot be sufficiently ensured. On the other hand, the Tg of the vinyl polymer (C) is generally 200 ° C. or lower due to restrictions on the raw material monomer and the like. The Tg of the vinyl polymer (C) is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher, and particularly preferably 80 ° C. or higher. It is above ℃. The upper limit of Tg is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, still more preferably 130 ° C. or lower, and even more preferably 120 ° C. or lower. The range of Tg of the vinyl polymer (C) is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 40 ° C. or higher and 140 ° C. or lower, still more preferably 50 ° C. or higher and 130 ° C. or lower, and even more preferably. Is 60 ° C. or higher and 120 ° C. or lower.

As the monomer constituting the vinyl polymer (C), various vinyl monomers having radical polymerizable properties can be used. Examples of the vinyl monomer include a hydrocarbon ester compound of (meth) acrylic acid, an aromatic vinyl compound, an unsaturated carboxylic acid, an unsaturated acid anhydride, a hydroxy group-containing unsaturated compound, and an amino group-containing unsaturated compound. Examples thereof include compounds, amide group-containing unsaturated compounds, alkoxy group-containing unsaturated compounds, nitrile group-containing unsaturated compounds, and maleimide-based compounds. These compounds may be used alone or in combination of two or more.

Examples of the hydrocarbon ester compound of (meth) acrylic acid include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, and (meth) acrylic acid. n-butyl, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, amyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, (meth) acrylate Alkyl (meth) acrylate compounds such as ethylhexyl, n-dodecyl (meth) acrylate, n-octadecyl (meth) acrylate; cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, tert (meth) acrylate. -(Meta) acrylics such as butylcyclohexyl, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc. An aliphatic cyclic ester compound of an acid; an aromatic ester compound of (meth) acrylic acid such as phenyl (meth) acrylic acid and benzyl (meth) acrylic acid can be mentioned.

Examples of the amino group-containing unsaturated compound include dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, and 2-diethylaminoethyl (meth) acrylate, (. 2- (Di-n-propylamino) ethyl (meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, 2-diethylaminopropyl (meth) acrylate, 2- (di-n-propyl) (meth) acrylate Examples thereof include amino) propyl, 3-dimethylaminopropyl (meth) acrylate, 3-diethylaminopropyl (meth) acrylate, and 3- (di-n-propylamino) propyl (meth) acrylate.

Examples of the amide group-containing unsaturated compound include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylol (meth) acrylamide and the like. Examples of the alkoxy group-containing unsaturated compound include (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid 2-ethoxyethyl, (meth) acrylic acid 2- (n-propoxy) ethyl, and (meth) acrylic acid. 2- (n-Butoxy) ethyl, (meth) acrylate 3-methoxypropyl, (meth) acrylate 3-ethoxypropyl, (meth) acrylate 2- (n-propoxy) propyl, (meth) acrylate 2- Examples thereof include (n-butoxy) propyl and the like.

Examples of the nitrile group-containing unsaturated compound include cyanomethyl (meth) acrylate, 1-cyanoethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, 1-cyanopropyl (meth) acrylate, and (meth) acrylic. 2-cyanopropyl acid, 3-cyanopropyl (meth) acrylic acid, 4-cyanobutyl (meth) acrylic acid, 6-cyanohexyl (meth) acrylic acid, 2-ethyl-6-cyanohexyl (meth) acrylic acid, ( Examples thereof include 8-cyanooctyl acrylate, (meth) acrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, and α-fluoroacrylonitrile.

As for the aromatic vinyl compound, unsaturated carboxylic acid, unsaturated acid anhydride, hydroxy group-containing unsaturated compound and maleimide-based compound, the compounds exemplified in the description of the block copolymer (P) can be exemplified. Further, in the production of the vinyl polymer (C), in addition to the above compounds, unsaturated dicarboxylic acid dialkyl esters, vinyl ester compounds, vinyl ether compounds and the like can also be used.

Among these, the vinyl polymer (C) is a polymer containing a structural unit derived from a hydrocarbon-based ester compound of (meth) acrylic acid in that it has appropriate compatibility with the block copolymer (P). It is preferable to have. In the vinyl polymer (C), the content of the structural unit derived from the hydrocarbon-based ester compound of (meth) acrylic acid is 30% by mass or more with respect to the total monomer unit of the vinyl polymer (C). A range of 100% by mass or less is preferable. The content of the structural unit derived from the hydrocarbon-based ester compound of (meth) acrylic acid is more preferably 50% by mass or more, still more preferably 50% by mass, based on all the monomer units of the vinyl polymer (C). It is 70% by mass or more, and more preferably 80% by mass or more.

In the production of the vinyl polymer (C), it is preferable to use an aliphatic cyclic ester compound of (meth) acrylic acid because Tg can be relatively high and the adhesive strength under high temperature conditions can be high. In the vinyl polymer (C), the content of the structural unit derived from the aliphatic cyclic ester compound of (meth) acrylic acid is 1% by mass with respect to all the monomer units of the vinyl polymer (C). The above is preferable, 5% by mass or more is more preferable, 10% by mass or more is further preferable, and 15% by mass or more is further preferable. The upper limit of the content of the structural unit derived from the aliphatic cyclic ester compound of (meth) acrylic acid is preferably 90% by mass or less, preferably 80% by mass or less, based on all the monomer units of the vinyl polymer (C). It is more preferably mass% or less, and further preferably 70% by mass or less. The content range of the structural unit is preferably 1% by mass or more and 90% by mass or less, more preferably 5% by mass or more and 80% by mass or less, and further preferably 10% by mass or more and 70% by mass or less.

Among these, as the aliphatic cyclic ester compound of (meth) acrylic acid, Tg can be set high, and the vinyl polymer (C) is easily segregated on the surface when the pressure-sensitive adhesive layer is formed, and has good heat resistance. At least one selected from the group consisting of isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate and adamantyl (meth) acrylate is preferable in that It can be used, and among them, isobornyl (meth) acrylate can be more preferably used.

The Mn of the vinyl polymer (C) is 500 or more and 10,000 or less. When Mn exceeds 10,000, segregation of the vinyl polymer (C) is not sufficient in the pressure-sensitive adhesive layer, and the adhesiveness and heat resistance under high temperature conditions are lowered, or the vinyl polymer (P) is combined with the block copolymer (P). Compatibility is reduced. Further, in order to produce a polymer having a Mn of less than 500, it is necessary to use a large amount of a polymerization initiator and a chain transfer agent, and there is a concern that productivity may decrease. The Mn of the vinyl polymer (C) is preferably 1,000 or more, more preferably 1,500 or more, still more preferably 2,000 or more. The upper limit of Mn of the vinyl polymer (C) is preferably 9,500 or less, more preferably 9,000 or less, still more preferably 7,000 or less, still more preferably 5,000 or less. Is. The range of Mn of the vinyl polymer (C) is preferably 1,000 or more and 9,500 or less, more preferably 1,000 or more and 9,000 or less, and further preferably 1,500 or more and 7, It is 000 or less, and more preferably 1,500 or more and 5,000 or less.

In the vinyl polymer (C), the molecular weight distribution (Mw / Mn) represented by the ratio of Mw and Mn is preferably 3.0 or less in that good adhesive strength can be easily obtained. Mw / Mn is more preferably 2.5 or less, still more preferably 2.0 or less. The lower limit of Mw / Mn of the vinyl polymer (C) is not particularly limited and is 1.0 or more.

It is preferable that the vinyl polymer (C) has a property of phase separation from the block copolymer (P). Having such a property makes it easy for the vinyl polymer (C) to segregate on the surface layer portion in the pressure-sensitive adhesive layer formed by using the present pressure-sensitive adhesive composition, and when the pressure-sensitive adhesive composition has a relatively low viscosity. Is also suitable in that it can form a pressure-sensitive adhesive layer having high heat resistance and durability against temperature changes. As described above, the SP value of the vinyl polymer (C) calculated by the method for calculating the SP value, which is a known solubility parameter (for example, the Fedors method), was compared with the SP value of the block copolymer (P). The vinyl polymer (C) phase-separated from the block copolymer (P) can be designed by adjusting the difference ΔSP (absolute value) to be appropriately large.

The vinyl polymer (C) can be obtained by polymerizing the above-mentioned monomer by adopting a known radical polymerization method such as a solution polymerization method, a suspension polymerization method, an emulsion polymerization method and a bulk polymerization method. .. In the case of the solution polymerization method, for example, an organic solvent and a monomer are charged in a reactor, a polymerization initiator is added, and the mixture is heated to 50 to 300 ° C. for copolymerization to obtain a target vinyl polymer (C). ) Can be obtained. The method for charging each raw material containing a monomer may be a batch-type initial batch charging in which all raw materials are collectively charged, or a semi-continuous charging method in which at least a part of the raw materials is continuously supplied into the reactor. A continuous polymerization method may be used in which all the raw materials are continuously supplied and the produced resin is continuously extracted from the reactor at the same time. When preparing the pressure-sensitive adhesive composition, the vinyl polymer (C) may be used as the polymer solution dissolved in the organic solvent, or the organic solvent may be distilled off by heat reduction treatment or the like. ..

An organic hydrocarbon compound is suitable as the organic solvent used in the solution polymerization method. Examples of the organic hydrocarbon compound include cyclic ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbon compounds such as benzene, toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone and cyclohexanone. , Methyl orthostate, methyl orthoacetate, methanol, ethanol, isopropanol and other alcohols can be exemplified. As the organic solvent, one or more of these can be used. The amount of the organic solvent used is such that the total amount of the monomers used for the polymerization is, for example, 1 to 50% by mass with respect to the total amount of the organic solvent and the monomer.

As the polymerization initiator, known radical polymerization initiators such as azo compounds, organic peroxides, and inorganic peroxides can be used, and are not particularly limited. Further, as the polymerization initiator, a redox-type polymerization initiator composed of a known oxidizing agent and reducing agent may be used. Furthermore, a known chain transfer agent can be used in combination with the polymerization initiator. Of these, an azo compound can be preferably used as the polymerization initiator. Specific examples of the azo compound include compounds exemplified as azo compounds that may be used in the production of the block copolymer (P). In the production of the vinyl polymer (C), the amount of the polymerization initiator used is, for example, 0.01 to 20 parts by mass with respect to 100 parts by mass of all the monomers used for the polymerization.

The present pressure-sensitive adhesive composition contains the vinyl polymer (C) in a range of 0.5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the block copolymer (P) in terms of solid content. When the content of the vinyl polymer (C) is less than 0.5 parts by mass, the amount of the vinyl polymer (C) on the surface layer portion of the pressure-sensitive adhesive layer is small, and the adhesive strength under high temperature conditions is lowered. Further, when the content of the vinyl polymer (C) exceeds 60 parts by mass, the flexibility of the pressure-sensitive adhesive layer is lowered, the pressure-sensitive adhesive layer becomes hard and brittle, the adhesiveness is lowered, and the transparency is lowered. There is a risk of doing so. From this point of view, the lower limit of the content of the vinyl polymer (C) is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more with respect to 100 parts by mass of the block copolymer (P). Yes, more preferably 2 parts by mass or more. The upper limit of the content of the vinyl polymer (C) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 25 parts by mass with respect to 100 parts by mass of the block copolymer (P). It is not less than parts by mass, and more preferably 15 parts by mass or less.

The content range of the vinyl polymer (C) is preferably 0.5 parts by mass or more and 40 parts by mass or less, more preferably 0.5 parts by mass, based on 100 parts by mass of the block copolymer (P). It is 5 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 25 parts by mass or less, and further preferably 1 part by mass or more and 25 parts by mass or less.

<Other ingredients>
The present pressure-sensitive adhesive composition may contain only the block copolymer (P) and the vinyl polymer (C), but if necessary, the block copolymer (P) and the vinyl polymer (C). It may contain components such as polymers and additives other than the above (hereinafter, also referred to as “other components”). Hereinafter, other components that may be blended in the pressure-sensitive adhesive composition will be described.

(Crosslinking agent)
When the block copolymer (P) has a crosslinkable functional group, the adhesiveness, heat resistance and temperature under high temperature conditions can be obtained by blending a crosslinking agent capable of reacting with the crosslinkable functional group into the pressure-sensitive adhesive composition. It is preferable in that the durability against changes can be further improved.

Examples of the cross-linking agent (hardener) include a glycidyl compound having two or more glycidyl groups, an isocyanate compound having two or more isocyanate groups, an aziridine compound having two or more aziridinyl groups, an oxazoline compound having an oxazoline group, and a metal chelate compound. Examples thereof include a butylated melamine compound. Among these, isocyanate compounds are preferable because they have excellent adhesive properties under high temperature conditions.

As a specific example of the cross-linking agent, examples of the glycidyl compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and tetraglycidyl xylene diamine. , 1,3-Bis (N, N-diglycidyl aminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether and other polyfunctional glycidyl compounds can be mentioned.
Examples of the isocyanate compound include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylenedi isocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and trizine diisocyanate. Aromatic isocyanate compounds such as (TODI); aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI) and lysine diisocyanate (LDI); isophorone diisocyanate (IPDI), cyclohexyldiisocyanate (CHDI), hydrogenated XDI (H6XDI), And alicyclic isocyanate compounds such as hydrogenated MDI (H12MDI); urethane modified, dimer, trimer, carbodiimide modified, urea modified, isocyanurate modified, oxazolidone modified, and isocyanate group-terminated pre. Examples thereof include modified isocyanate compounds such as polymers.
Examples of the aziridine compound include 1,6-bis (1-aziridinylcarbonylamino) hexane, 1,1'-(methylene-di-p-phenylene) bis-3,3-aziridylurea, and ethylenebis- (2-). Aziridinyl propionate), 2,4,6-triaziridinyl-1,3,5-triazine, trimethylpropan-tris (2-aziridinylpropionate) and the like.

When the cross-linking agent is blended in the pressure-sensitive adhesive composition, the content of the cross-linking agent in the pressure-sensitive adhesive composition is not particularly limited, but is usually 0.01 to 10% by mass with respect to the content of the block copolymer (P). It is preferably 0.03 to 5% by mass, and more preferably 0.05 to 2% by mass.

(Adhesive)
The present pressure-sensitive adhesive composition may further contain a pressure-sensitive adhesive. Examples of the tackifier include rosin derivatives such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin, and disproportionated rosin ester; terpene phenol resin, α-pinene, β-pinene, or. Terpene-based resins mainly composed of rosinen and the like; kumaron-inden-based resins, hydride aromatic copolymers, phenol-based resins and the like can be mentioned. The tackifier may be used alone or in combination of two or more. The content of the tackifier is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, based on the total amount of the block copolymer (P) and the vinyl polymer (C). More preferably, it is 0 to 5% by mass.

(Plasticizer)
The present pressure-sensitive adhesive composition may contain a plasticizer. Examples of the plasticizer include phthalates such as din-butylphthalate, din-octylphthalate, bis (2-ethylhexyl) phthalate and din-decylphthalate; bis (2-ethylhexyl) adipate and din-octyl adipate. Adipic acid esters such as; sevacinic acid esters; azelaic acid esters; paraffins such as chlorinated paraffin; glycols such as polypropylene glycol; epoxy-modified vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; trioctyl Phthalate esters such as phosphate and triphenyl phosphate; Ester oligomers such as esters of adipic acid and 1,3-butylene glycol; low molecular weight polybutene, low molecular weight poly Low molecular weight polymers such as isobutylene and low molecular weight polyisoprene; oils such as process oils and naphthenic oils can be mentioned. The content of the plasticizer is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, based on the total amount of the block copolymer (P). be.

Other additives to be blended in the pressure-sensitive adhesive composition include, for example, antioxidants, ultraviolet absorbers, antioxidants, flame retardants, fungicides, silane coupling agents, fillers, colorants and the like. Be done. The content of the additive can be appropriately set according to various compounds as long as the effects of the present disclosure are not impaired.

(solvent)
The present pressure-sensitive adhesive composition may be a liquid composition in which the block copolymer (P), the vinyl polymer (C), and the additive component to be blended as necessary are dissolved or dispersed in a solvent. good. As the solvent used for preparing the pressure-sensitive adhesive composition, an organic solvent capable of dissolving the block copolymer (P) and the vinyl polymer (C), or the block copolymer (P) and the vinyl polymer (C) can be used. Examples include dispersible aqueous media. Specific examples of the organic solvent include aprotonic polar solvent, phenol solvent, alcohol solvent, ester solvent, ketone solvent, ether solvent, hydrocarbon solvent and the like. The organic solvent may be one of these or a mixed solvent of two or more.

<Preparation of adhesive composition>
The present pressure-sensitive adhesive composition is not particularly limited in its form as long as it contains the block copolymer (P) and the vinyl polymer (C). For example, by dissolving the block copolymer (P) and the vinyl polymer (C) in one or more organic solvents of ethyl acetate, butyl acetate, ethyl methyl ketone and toluene, a solvent-type pressure-sensitive adhesive composition can be obtained. Obtainable. Further, by dispersing the block copolymer (P) and the vinyl polymer (C) in an aqueous medium, an emulsion-type pressure-sensitive adhesive composition can be obtained.

In addition to the block copolymer (P) and vinyl polymer (C), the present pressure-sensitive adhesive composition contains monofunctional and / or polyfunctional (meth) acrylic monomers, photopolymerization initiators, and the like. The composition may be a so-called syrup-type active energy ray-curable pressure-sensitive adhesive composition that is cured by active energy rays such as ultraviolet rays. In the case of an active energy ray-curable pressure-sensitive adhesive composition, the composition may contain a solvent such as an organic solvent, but is usually used as a solvent-free type containing no solvent.

In the case of a solvent-type pressure-sensitive adhesive composition, the solid content concentration in the pressure-sensitive adhesive composition (that is, the ratio of the mass of the non-solvent component in the pressure-sensitive adhesive composition to the total mass of the pressure-sensitive adhesive composition) is not particularly limited. However, it is preferably 1 to 70% by mass. When the solid content concentration is 1% by mass or more, a pressure-sensitive adhesive layer having a sufficient thickness can be formed. Further, when the solid content concentration is 70% by mass or less, good coatability can be ensured, and a pressure-sensitive adhesive layer having a uniform thickness can be easily formed. The solid content concentration in the pressure-sensitive adhesive composition is more preferably 5 to 50% by mass, still more preferably 10 to 45% by mass.

The viscosity of the pressure-sensitive adhesive composition is preferably 500 mPa · s or more and 10,000 mPa · s or less. When the viscosity is 10,000 mPa · s or less, good coatability can be ensured. Further, when coating, it can be used as it is without diluting to a viscosity suitable for coating, and the handleability is good. From this point of view, the viscosity of the pressure-sensitive adhesive composition is more preferably 8,000 mPa · s or less, further preferably 6,000 mPa · s or less, and even more preferably 5,000 mPa · s or less. Further, the lower limit of the viscosity of the pressure-sensitive adhesive composition is more preferably 1,000 mPa · s or more, still more preferably 1,500 mPa · s or more, from the viewpoint of suppressing the film thickness from becoming too thin. Even more preferably, it is 2,000 mPa · s or more. The viscosity range of the pressure-sensitive adhesive composition is more preferably 1,000 mPa · s or more and 8,000 mPa · s or less, further preferably 1,000 mPa · s or more and 6,000 mPa · s or less, and further preferably 1,500 mPa · s. More than 5,000 mPa · s or less is more preferable. The viscosity of the pressure-sensitive adhesive composition is a value measured at 25 ° C. using a pressure-sensitive adhesive composition having a solid content concentration of 25% using a B-type viscometer. The pressure-sensitive adhesive composition preferably contains, as a solvent, at least one organic solvent selected from the group consisting of ethyl acetate, butyl acetate, ethyl methyl ketone and toluene.

<Adhesive layer>
The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition to a separator or the like and drying it if necessary. As the separator, a resin film made of various resin materials can be used. Examples of the resin material include polyester resins such as polyethylene terephthalate, polyether sulfone resins, acetate resins, polycarbonate resins, and polyolefin resins. For example, in order to form a pressure-sensitive adhesive layer using a liquid pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is applied to a separator by a known coating method, and the solvent is removed by a drying treatment such as heating. The heating temperature and heating time for forming the pressure-sensitive adhesive layer may be set as long as the solvent can be removed, and can be appropriately set according to the type of the solvent, the solid content concentration, and the like. In the case of the pressure-sensitive adhesive layer for a decorative film, the thickness of the pressure-sensitive adhesive layer is, for example, 2 to 200 μm. Further, in order to make the pressure-sensitive adhesive layer of the decorative film a desired thickness, the pressure-sensitive adhesive layer may be formed by laminating a plurality of layers.

(Storage modulus)
The pressure-sensitive adhesive layer formed by using the present pressure-sensitive adhesive composition has a storage elastic modulus (G') at 110 ° C. in that it can form a pressure-resistant and durable pressure-sensitive adhesive layer particularly in a high-temperature environment. It is preferably 5 × 10 ⁴ Pa or more. The storage elastic modulus is more preferably 2.0 × 10 ⁴ Pa or more, further preferably 2.5 × 10 ⁴ Pa or more, still more preferably 3.0 × 10 ⁴ Pa or more, and further preferably. Is 4.0 × 10 ⁴ Pa or more. The upper limit of the storage elastic modulus is not particularly limited, but may be, for example, 50.0 × 10 ⁴ Pa or less, and ^{may be 20.0 × 10 4} Pa or less.

In the present specification, the storage elastic modulus at 110 ° C. measures the shear viscoelasticity of a pressure-sensitive adhesive layer having a thickness of 0.8 mm under the conditions of a heating rate of 2 ° C./min, a strain of 0.1%, and a measurement frequency of 1 Hz. It is a value obtained by doing. As for the details of the method for measuring the storage elastic modulus, the method described in Examples described later can be adopted. The storage elastic modulus can be arbitrarily adjusted by adjusting the composition of the block copolymer (P), the ratio of the polymer block (A) to the acrylic polymer block (B), the degree of cross-linking, and the like. .. For example, a (meth) acrylic acid alkyl compound having an alkyl group having 1 to 4 carbon atoms and an alkoxyalkyl group having 2 to 4 carbon atoms (meth) acrylic acid alkoxy as a constituent monomer of the block copolymer (P). The storage elasticity can be adjusted by using one or more of the alkyl compounds and adjusting the type and amount of these monomers.

(Gel fraction)
When the present pressure-sensitive adhesive composition contains a cross-linking agent, the gel fraction of the pressure-sensitive adhesive layer made of the present pressure-sensitive adhesive composition is preferably 50% or more. By setting the gel fraction to 50% or more, the heat resistance of the pressure-sensitive adhesive layer and the durability against temperature changes can be sufficiently enhanced. The gel fraction of the pressure-sensitive adhesive layer is preferably 55% or more, more preferably 58% or more. The upper limit of the gel fraction is preferably 95% or less, more preferably 90% or less, still more preferably 85% or less. In the present specification, the gel fraction of the pressure-sensitive adhesive layer is the ratio of the mass W2 of the residue of the pressure-sensitive adhesive layer remaining after immersion in the solvent to the initial mass W1 of the pressure-sensitive adhesive layer. The details follow the measurement method of the examples described later.

(Peeling strength)
Acrylonitrile-butadiene-styrene (ABS) at 23 ° C. and a peeling rate of 300 mm / min for a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer having a thickness of 50 μm and a thickness of 100 μm on a polyethylene terephthalate (PET) film substrate. ) The peeling strength to the plate is preferably 15 N / 25 mm or more from the viewpoint of obtaining a decorative film that is less likely to float or peel from the molded body at room temperature. The peel strength at 23 ° C. is more preferably 20 N / 25 mm or more, still more preferably 25 N / 25 mm or more.

Further, for a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer having a thickness of 50 μm made of the present pressure-sensitive adhesive composition on a PET film substrate having a thickness of 100 μm, the peeling strength with respect to the ABS plate at 80 ° C. and a peeling speed of 300 mm / min is high. However, from the viewpoint of obtaining a decorative film having high heat resistance and durability, which is less likely to cause floating or peeling from the molded body, it is preferably 10 N / 25 mm or more. The peel strength at 80 ° C. is more preferably 15 N / 25 mm or more, further preferably 20 N / 25 mm or more, and even more preferably 25 N / 25 mm or more. The details of the method for measuring the peel strength follow the measuring method of Examples described later. The characteristic that the pressure-sensitive adhesive layer according to the present pressure-sensitive adhesive composition exhibits high adhesiveness even under high temperature conditions is based on the Tg composition (distribution) of the pressure-sensitive adhesive layer generated by segregation of the vinyl polymer (C). It can have high adhesiveness under high temperature conditions regardless of the type of material of the adherend.

<Decorative film>
The decorative film of the present disclosure (hereinafter, also referred to as "the present decorative film") includes a pressure-sensitive adhesive layer made of the present pressure-sensitive adhesive composition. For this reason, this decorative film does not easily peel off from the molded product even when exposed to a high temperature of 100 ° C. or higher after being bonded to the molded product, has excellent high-temperature adhesiveness, and has excellent heat resistance and temperature change. Has excellent durability against.

One aspect of the present decorative film is a laminate in which the pressure-sensitive adhesive layer, the decoration layer, and the base material layer made of the present pressure-sensitive adhesive composition are laminated in this order. The decorative film having such a structure can be preferably used in a laminating method for obtaining a decorative molded body by laminating the decorative film with the molded body.

The base material layer is located on the outermost layer of the decorative molded body after the molded body is decorated with the decorative film, and functions as a protective layer of the decorative molded body. The material constituting the base material layer may be any material having flexibility, and a resin material is preferable. More preferably, it is a thermoplastic resin. The thermoplastic resin is not particularly limited, and examples thereof include vinyl chloride (PVC) resin, polyester resin, acrylic resin, ABS resin, polycarbonate resin, polypropylene resin, and polyethylene resin. Of these, the base material layer is preferably formed of at least one selected from the group consisting of PVC resin, polyester resin and ABS resin.

The thickness of the base material layer is preferably 25 μm to 500 μm, more preferably 50 μm to 400 μm, and further preferably 100 to 300 μm. When the thickness of the base material layer is within the above range, when the decorative molded body is manufactured by an injection molding method (also referred to as an insert molding method), a vacuum forming method, a vacuum pressure pneumatic molding method, etc. Shape followability and handleability are improved.

The decorative layer is an ink layer to which patterns and patterns such as texts, figures and trademarks are added by printing or the like. This decorative layer gives the decorative film a design. The design and pattern of the decorative layer can be formed by known printing methods such as gravure printing with printing ink, offset printing, silk screen printing, transfer printing from a transfer sheet, sublimation transfer printing, and inkjet printing. The thickness of the decorative layer is preferably 1 to 40 μm, more preferably 1 to 30 μm. When the thickness of the decorative layer is within the above range, it is possible to secure a sufficient thickness for expressing a complicated design such as a gradation. Further, the surface of the decorative film may be provided with an uneven pattern. The uneven pattern can be formed, for example, by transferring the uneven pattern with an embossing roller.

The decorative film may further have a release layer on the outermost layer on the adhesive layer side. The peeling layer prevents unintended adhesion and is peeled off when the present decorative film is adhered to the molded body. The material constituting the release layer is not particularly limited, but for example, polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and resin materials such as polypropylene and polyolefin such as polyethylene; glassin paper, kraft paper, clay coat paper, and the like. Paper material can be used. The thickness of the release layer can be about 10 to 400 μm.

In addition, the present decorative film may be configured to include a hard coat layer (protective layer), a decorative layer, and an adhesive layer on the release layer of the release film provided with the release layer. The decorative film having such a structure can be suitably used as a transfer film. In the decorative film having this configuration, a decorative molded body can be obtained by a transfer method of transferring from the hard coat layer to the pressure-sensitive adhesive layer to the molded body. In the case of the above laminating method, it is necessary to remove the excess film by trimming after the decorative molding, but the transfer method does not require a trimming process, which is advantageous in terms of production efficiency.

The hardcourt layer is in a tack-free state before being transferred, and is composed of a material that can be cured and / or crosslinked by irradiation with active energy rays or the like after being transferred to a molded product. Is preferable. Examples of the material constituting the hard coat layer include a polymer or oligomer having a (meth) acryloyl group, an active energy ray-curable composition irradiated with an appropriate amount of active energy rays to make it in a semi-cured state, or active energy. Examples thereof include a linear curable resin composition in which an isocyanate compound, a polyol resin and the like are blended and appropriately crosslinked. The thickness of the hard coat layer is not particularly limited, but can be about 1 to 50 μm, preferably about 2 to 40 μm.

<Decorative molded body>
According to the present disclosure, a decorative molded body (hereinafter, also referred to as “main decorative molded body”) including the present decorative film is provided. Since the decorative molded body is decorated with a decorative film provided with an adhesive layer obtained by using the adhesive composition, the decorative film is less likely to float or peel off even under high temperature conditions, and is heat resistant. It has excellent properties and durability.

The molded body to which the decorative film is adhered is not particularly limited, and any article such as a resin product, a metal product, a ceramic product, a glass product, etc., to which the decorative film can be adhered may be used. Specifically, for example, various home appliances such as household appliances, kitchen appliances, health appliances, seasonal home appliances; interior / exterior members of housing equipment such as toilets, bathrooms, doors, walls; bumpers, dashboards, doors, roofs, etc. Automotive interiors and exteriors such as bonnets; various miscellaneous goods such as household goods and daily necessities; electronic parts; nursing and medical supplies; interior and exterior parts of ships and aircraft.

A vacuum forming method, a vacuum pressure pneumatic molding method, an injection molding method, or the like can be used for manufacturing this decorative molded body. In the vacuum forming method, the decorative film is stretched while being heated and softened, and the space on the molded body side of the decorative film is depressurized, so that the decorative film is bonded while being molded along the surface shape of the molded body. .. In the vacuum forming method, after the forming step of the vacuum forming method, the space on the opposite side is further pressed to bond the decorative film while forming along the surface shape of the molded body. Examples of the vacuum compressed air molding machine include a hot plate type pressure reducing coating molding machine TFH series manufactured by Asano Laboratories, a TOM molding machine NGF series manufactured by Fuse Vacuum, and a NATS air transfer machine manufactured by Navitas. In the injection molding method, the decorative film is set in the mold cavity of the injection molding machine, and injection molding is performed to bond the decorative film along the surface shape of the molded body. By these methods, the present decorative molded article can be obtained.

Hereinafter, the present disclosure will be specifically described with reference to examples. However, the present disclosure is not limited to these examples. In the following description, "part" means "part by mass" and "%" means "% by mass". Various analyzes in Examples and Comparative Examples were carried out by the methods described below.

<Molecular weight measurement>
Using a gel permeation chromatograph device (model name "HLC-8320", manufactured by Tosoh Corporation), a polystyrene-equivalent number average molecular weight (Mn) and a weight average molecular weight (Mw) were obtained under the following conditions. Moreover, the molecular weight distribution (Mw / Mn) was calculated from the obtained values.
○ Measurement conditions Column: Tosoh TSKgel SuperMultipore HZ-M x 4 Column temperature: 40 ° C
Eluent: Tetrahydrofuran detector: RI
Flow velocity: 600 μL / min

<Mass ratio of (A) / (B) of block copolymer>
The mass ratio (block ratio) of (A) / (B) of the block copolymer was ^{identified and calculated by 1} H-NMR measurement. As a measuring device, a Bruker Ascend ^TM 400 nuclear magnetic resonance measuring device was used. Measurement was performed at 25 ° C. using tetramethylsilane as a standard substance and deuterated chloroform as a solvent.
<Polymer composition>
The monomer composition of the polymer was calculated from the amount of monomer charged and the amount of monomer consumed by gas chromatograph (GC) measurement. The GC measurement was carried out under the following conditions.
GC: Made by Agilent Technologies (7820A GC System), Detector: FID, Column: 100% dimethylsiloxane (CP-Sil 5CB) Column length 30 m, Column inner diameter 0.32 mm, Calculation method: Internal standard method

<Measurement of glass transition temperature (Tg)>
The glass transition temperature (Tg) of the polymer was determined from the intersection of the baseline of the heat flux curve obtained using a differential scanning calorimeter and the tangent at the inflection. The heat flux curve shows that about 10 mg of the sample is cooled to -50 ° C, held for 5 minutes, then heated to 300 ° C at 10 ° C / min, subsequently cooled to -50 ° C, held for 5 minutes, and then 10 ° C. It was obtained under the condition that the temperature was raised to 350 ° C. at / min.
Measuring equipment: DSC6220 manufactured by SII Nanotechnology Co., Ltd.
Measurement atmosphere: Under a nitrogen atmosphere The Tg of the polymer block (A) and the (meth) acrylic polymer block (B) (hereinafter, simply referred to as “polymer block (B)”) is the polymer block (A). ) And the polymer corresponding to the polymer block (B) were produced, respectively, and differential scanning calorimetry (DSC) was performed according to the above measurement method.

1. 1. Synthesis of Vinyl Polymer [Synthesis Example 1] Production of Polymer C-1 In a four-necked flask with an internal volume of 1 liter, butyl acetate (200 parts by mass) and dimethyl-2,2'-azobis (2-methylpropio) Nate) (manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601") (0.9 parts by mass) was charged with a mixed solution, and this mixed solution was sufficiently degassed by bubbling nitrogen gas to form the mixed solution. The internal temperature was raised to 90 ° C. Separately, methyl methacrylate (hereinafter referred to as "MMA") (165 parts by mass), isobornyl methacrylate (hereinafter referred to as "IBXMA") (44 parts by mass), V-601 (17 parts by mass), and butyl acetate (90 parts by mass). Polymerization was carried out by dropping a mixed solution consisting of (part by mass) from the dropping funnel into the flask over 5 hours. After completion of the dropping, the polymerization solution was added dropwise to a mixed solvent consisting of methanol (4800 parts by mass) and water (1200 parts by mass) to isolate the vinyl polymer in the polymerization solution to obtain the polymer C-1. .. As a result of calculating the monomer composition of the obtained polymer C-1 from the charged amount and the monomer consumption by GC measurement, the polymer C-1 was composed of 80% by mass of MMA and 20% by mass of IBXMA, and Mw = 6700. It was Mn = 4370 and Mw / Mn = 1.53. Tg was 108 ° C.

[Synthesis Example 2] Production of Polymer C-2 The initial charge is changed to butyl acetate (90 parts by mass) and V-601 (1.7 parts by mass), and the mixed solution to be dropped is MMA (80 parts by mass) and methacryl. The same operation as in Synthesis Example 1 was performed except that the acid-1-adamantyl (hereinafter referred to as "ADAM") (63 parts by mass), V-601 (33 parts by mass) and butyl acetate (90 parts by mass) were changed to vinyl weight. Combined C-2 was obtained.
[Synthesis Example 3] Production of Polymer C-3 The initial charge was changed to butyl acetate (200 parts by mass) and V-601 (7.5 parts by mass), and the mixed solution to be dropped was MMA (114 parts by mass) and IBXMA. The same operation as in Synthesis Example 1 was carried out except that the components were changed to (140 parts by mass), V-601 (121 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer C-3.

[Synthesis Example 4] Production of Polymer C-4 The initial charge is changed to butyl acetate (200 parts by mass) and V-601 (0.9 parts by mass), and the mixed solution to be dropped is MMA (60 parts by mass), IBXMA. The same operation as in Synthesis Example 1 was carried out except that the components were changed to (166 parts by mass), V-601 (18 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer C-4.
[Synthesis Example 5] Production of Polymer C-5 The initial charge is changed to butyl acetate (280 parts by mass) and V-601 (0.3 parts by mass), and the mixed solution to be dropped is MMA (180 parts by mass), IBXMA. The same operation as in Synthesis Example 1 was carried out except that the components were changed to (46 parts by mass), V-601 (6.2 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer C-5.

[Synthesis Example 6] Production of Polymer C-6 The initial charge is changed to butyl acetate (135 parts by mass) and V-601 (2.2 parts by mass), and the mixed solution to be dropped is MMA (100 parts by mass) and methacryl. The same operation as in Synthesis Example 1 was performed except that the components were changed to dicyclopentanyl acid (hereinafter referred to as “DCP”) (79 parts by mass), V-601 (41 parts by mass) and butyl acetate (90 parts by mass), and the vinyl weight was increased. Combined C-6 was obtained.
[Synthesis Example 7] Production of Polymer C-7 The initial charge was changed to butyl acetate (203 parts by mass) and V-601 (4.1 parts by mass), and the mixed solution to be dropped was MMA (168 parts by mass) and IBXMA. The same operation as in Synthesis Example 1 was carried out except that the components were changed to (83 parts by mass), V-601 (78 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer C-7.

[Synthesis Example 8] Production of Polymer C-8 The initial charge was changed to butyl acetate (280 parts by mass) and V-601 (0.3 parts by mass), and the mixed solution to be dropped was MMA (233 parts by mass) and IBXMA. The same operation as in Synthesis Example 1 was carried out except that the components were changed to (26 parts by mass), V-601 (5.1 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer C-8.
[Synthesis Example 9] Production of Polymer C-9 The initial charge is changed to butyl acetate (221 parts by mass) and V-601 (3.2 parts by mass), and the mixed solution to be dropped is MMA (34 parts by mass) and methacryl. The same operation as in Synthesis Example 1 was carried out except that the components were changed to n-butyl acid (hereinafter referred to as "BMA") (215 parts by mass), V-601 (60 parts by mass) and butyl acetate (90 parts by mass) to obtain a vinyl polymer. Obtained C-9.
The analysis results of the polymers C-1 to C-9 are shown in Table 1.

The abbreviations of the monomers in Table 1 are as follows.
MMA: Methyl Methacrylate IBXMA: Isobornyl Methacrylic Acid ADMA: -1-adamantyl Methacrylic Acid DCP: Dicyclopentanyl Methacrylate BMA: n-Butyl Methacrylate

2. 2. Synthesis of Polymer Block (A) [Synthesis Example 10] Production of Polymer Block A-1 Dibenzyltrithiocarbonate (hereinafter referred to as "DBTTC") (hereinafter referred to as "DBTTC") as a RAFT agent in a 1 L flask equipped with a stirrer and a thermometer (1). .91 parts by mass), 2,2'-azobis (2-methylbutyronitrile) (hereinafter referred to as "ABN-E") (0.25 parts by mass) as a polymerization initiator, styrene as a monomer (hereinafter, "St") (38 parts by mass), N-phenylmaleimide (hereinafter referred to as "PhMI") (62 parts by mass), and ethyl acetate (233 parts by mass) as a polymer were charged and sufficiently degassed by nitrogen bubbling. Polymerization was started in a constant temperature bath at 70 ° C. After 2 hours, the reaction was stopped by cooling to room temperature. The above polymerization solution was reprecipitated and purified from methanol and vacuum dried to obtain polymer block A-1. The obtained polymer block A-1 had Mw = 14,400, Mn = 10,900, Mw / Mn = 1.32, and Tg = 206 ° C. (see Table 4).

[Synthesis Examples 11 to 15] Production of Polymer Blocks A-2 to A-6 Same as Synthesis Example 10 except that the types and amounts of raw materials charged into the flask and the reaction conditions were changed as shown in Table 2. The same operation was carried out to obtain polymer blocks A-2 to A-6. The analysis results of each polymer block are shown in Tables 4 and 5.

The abbreviations for the monomers, RAFT agents and initiators in Table 2 are as follows.
PhMI: N-Phenylmaleimide St: Styrene HEMA: 2-Hydroxyethyl methacrylate DBTTC: Dibenzyltrithiocarbonate ABN-E: 2,2'-azobis (2-methylbutyronitrile)
V-65: 2,2'-azobis (2,4-dimethylvaleronitrile)

3. 3. Synthesis of Block Copolymer [Synthesis Example 16] Production of Block Copolymer P-1 In a 1 L flask equipped with a stirrer and a thermometer, the obtained polymer block A-1 (7 parts by mass) was used as a polymerization initiator. ABN-E (0.013 parts by mass), 2-methoxyethyl acrylate (hereinafter referred to as "MEA") (78 parts by mass) as a monomer, n-butyl acrylate (hereinafter referred to as "n-BA"). (17 parts by mass), 2-hydroxyethyl acrylate (hereinafter referred to as "HEA") (5 parts by mass), and ethyl acetate (60 parts by mass) as a polymer were charged, sufficiently degassed by nitrogen bubbling, and heated to 70 ° C. Polymerization was started in a constant temperature bath. After 6 hours, the mixture was cooled to room temperature, and the solid content concentration was adjusted to 30% by mass by adding ethyl acetate, and the polymer block (A), the polymer block (B), and the polymer block (A) were adjusted. A pressure-sensitive adhesive solution containing a (ABA) type triblock copolymer composed of (ABA) was obtained. The obtained block copolymer P-1 had Mw = 232,000, Mn = 144,000, and Mw / Mn = 1.61. The Tg of the polymer block (B) was −35 ° C.

[Synthesis Examples 17 to 28] Production of Block Copolymers P-2 to P-13 With the exception of Synthesis Example 16 except that the types and amounts of raw materials to be charged into the flask and the reaction conditions were changed as shown in Table 3. The same operation was carried out to obtain block copolymers P-2 to P-13. The analysis results of each block copolymer are shown in Tables 4 and 5.

4. Synthesis of Random Copolymer [Synthesis Example 29] Production of Random Copolymer P-14 MEA (78 parts by mass), n-BA (17 parts by mass), HEA (5 by mass) in a four-necked flask with an internal volume of 2 liters. (Parts by mass) and ethyl acetate (185 parts by mass) were charged, the mixed solution was sufficiently degassed by bubbling with nitrogen gas, the internal temperature of the mixed solution was raised to 40 ° C., and 2,2'-azobis (2,2'-azobis) ( 2,4-Dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., V-65) (0.047 parts by mass) was charged and polymerization was started. After 5 hours, ethyl acetate was added to a solid content concentration of 30% to obtain an ethyl acetate solution of the random copolymer P-14. The obtained random copolymer P-14 consisted of 78% by mass of MEA, 17% by mass of BA, and 5% by mass of HEA, and had Mw = 572,000, Mn = 160,000, and Mw / Mn = 3.58. Tg was −35 ° C. The analysis results of the random copolymer P-14 are shown in Table 6.

[Synthesis Examples 30 and 31] Production of Random Copolymers P-15 and P-16 The same operation as in Synthesis Example 29 was performed except that the types and amounts of the raw materials charged in the flask were changed as shown in Table 3. This was carried out to obtain random copolymers P-15 and P-16. The analysis results of each random copolymer are also shown in Table 6.

5. Production and Evaluation of Adhesive Composition [Example 1]
The vinyl polymer C-1 obtained in Synthesis Example 1 was dissolved in ethyl acetate to prepare a polymer C-1 solution having a solid content concentration of 30% by mass. The polymer C-1 solution (4 parts by mass) and the block copolymer P-1 solution (100 parts by mass) obtained in Synthesis Example 8 having a solid content concentration of 30% by mass are mixed to obtain a pressure-sensitive adhesive composition. Obtained.

This pressure-sensitive adhesive composition was applied onto a PET separator having a thickness of 50 μm so that the thickness of the pressure-sensitive adhesive layer after drying was 50 ± 2.0 μm. Ethyl acetate is removed by drying the pressure-sensitive adhesive composition at 80 ° C. for 4 minutes, a PET separator having a thickness of 38 μm, which has a different peeling power from the above separator, is attached, and the mixture is allowed to stand at 40 ° C. for 5 days for aging. By (aging), an adhesive film sample with a double-sided separator was obtained. The obtained adhesive film sample was subjected to various measurements and evaluations by the following methods. The results of measurement and evaluation are shown in Table 4.

<Viscosity measurement of adhesive solution>
The above pressure-sensitive adhesive composition was diluted with ethyl methyl ketone to prepare a pressure-sensitive adhesive solution having a solid content concentration of 25%, and the viscosity (mPa · s) was measured at 25 ° C. using a B-type viscometer.
<Gel fraction>
0.2 g of the pressure-sensitive adhesive was collected from the pressure-sensitive adhesive film sample, and the initial mass W1 of the pressure-sensitive adhesive was weighed. The pressure-sensitive adhesive was immersed in 50 g of ethyl acetate and allowed to stand at room temperature for 16 hours. Then, the mixture was filtered through a 200 mesh wire mesh, and the residue remaining on the mesh was dried at 80 ° C. for 3 hours and weighed. The gel fraction (%) of the pressure-sensitive adhesive layer was calculated from the ratio of the residual mass W2 to the initial mass W1.
Gel fraction (%) = (W2 / W1) x 100

<Measurement of storage elastic modulus at 110 ° C>
A 50 μm thick pressure-sensitive adhesive film sample was laminated until the thickness became 0.8 mm to obtain an evaluation pressure-sensitive adhesive sheet. This is punched into a circle with a diameter of 8 mm, and a strain is applied at a frequency of 1 Hz while raising the temperature from -50 ° C to 150 ° C at 2 ° C / min using a shear viscoelastic device (Physica MCR-301 manufactured by Anton Pearl). Dynamic viscoelasticity was measured at 0.1% and the shear storage modulus at 110 ° C. was read. A parallel plate of 8 mmφ was used for the measurement.

<Peeling strength test for ABS plate>
The pressure-sensitive adhesive film sample was transferred to a PET film (100 μm) that had been easily bonded to obtain a pressure-sensitive adhesive sheet for evaluation. The adherend is an ABS plate (manufactured by TP Giken Co., Ltd., 2 mm thick), the above-mentioned adhesive sheet for evaluation is attached, and a precision heating and pressurizing device (manufactured by Shinto Kogyo Co., Ltd.) is used at 0.8 MPa, 120 ° C. It was crimped for 20 seconds under the conditions of. After that, using a tensile tester Strograph R type (manufactured by Toyo Seiki Co., Ltd.) with a constant temperature bath, the temperature is 23 ° C. and the peeling speed is 300 mm / min, according to JIS Z-0237 "Adhesive Tape / Adhesive Sheet Test Method". The 180 ° peel strength (N / 25 mm) of the adhesive sheet was measured.
Further, the same operation as described above was performed except that the temperature of the peel strength test was changed from 23 ° C to 80 ° C, and the 180 ° peel strength (N / 25 mm) of the pressure-sensitive adhesive sheet was measured.

<Cold heat cycle characteristic test (durability test against temperature change)>
A vinyl chloride decorative film (manufactured by Nippon Wave Rock Co., Ltd., 200 μm thick) was attached to a 5 cm × 6 cm pressure-sensitive adhesive film sample to prepare a decorative film with an adhesive layer. This decorative film with an adhesive layer was stretched at a stretch ratio of 200% and bonded to an ABS plate for molding. The decorative film was bonded to the ABS plate using a vacuum compressed air molding machine (NATS-0612B type manufactured by Navitas) under the conditions of a film heating temperature of 120 ° C. and a compressed air of 0.2 MPa. Then, a cross cut was made in the molded decorative film with a cutter, and a cooling / heating cycle of 80 ° C./-30 ° C. was performed for 30 cycles (holding time at each temperature was 30 minutes). After the end of the cooling cycle, the appearance of the cross-cut portion was visually confirmed and evaluated according to the following criteria.
⊚: Peeling or misalignment of the decorative film is 0.5 mm or less ○: Peeling or misalignment of the decorative film is greater than 0.5 mm and 1 mm or less Δ: Peeling or misalignment of the decorative film is greater than 1 mm and 2 mm or less ×: Peeling or misalignment of decorative film is larger than 2 mm

<Heat resistance test>
A vinyl chloride decorative film (manufactured by Nippon Wave Rock Co., Ltd., 200 μm thickness) was attached to the adhesive film sample to prepare a decorative film with an adhesive layer. This decorative film with an adhesive layer was stretched at a stretch ratio of 200% and bonded to an ABS plate for molding. The decorative film was bonded to the ABS plate using a vacuum compressed air molding machine (NATS-0612B type manufactured by Navitas) under the conditions of a film heating temperature of 120 ° C. and a compressed air of 0.2 MPa. Then, a cross cut was put into the molded decorative film with a cutter, and the mixture was left at 110 ° C. for 15 hours. After a lapse of time, the appearance of the cross-cut portion was visually confirmed and evaluated according to the following criteria.
⊚: Peeling or misalignment of the decorative film is 0.5 mm or less ○: Peeling or misalignment of the decorative film is greater than 0.5 mm and 1 mm or less Δ: Peeling or misalignment of the decorative film is greater than 1 mm and 2 mm or less ×: Peeling or misalignment of decorative film is larger than 2 mm

[Examples 2 to 27 and Comparative Examples 1 to 8]
In Example 1, a pressure-sensitive adhesive composition was prepared by substituting the types and blending ratios of the vinyl polymer and the copolymer as shown in Tables 4 to 6. In Examples 10 to 27 and Comparative Example 7, Takenate D-110N (solid content concentration 75% by mass, manufactured by Mitsui Kagaku Co., Ltd.) was used as a cross-linking agent, and the solid content concentration ratios shown in Tables 4 to 6 (that is, that is, It was added so as to be the ratio of the cross-linking agent (solid content) to 100 parts by mass of the solid content of the block copolymer or the random copolymer. Moreover, the same measurement and evaluation as in Example 1 were carried out using the obtained pressure-sensitive adhesive composition. The results of measurement and evaluation are shown in Tables 4-6.

The abbreviations of the monomers and the details of the cross-linking agent in Tables 4 to 6 are as follows.
PhMI: N-Phenylmaleimide St: Styrene HEMA: 2-Hydroxyethyl methacrylate MEA: 2-Methyl acrylate n-BA: n-butyl acrylate MA: Methyl acrylate HEA: 2-Hydroxyethyl acrylate Crosslinker: Takenate D-110N manufactured by Mitsui Chemicals, Inc. (isocyanate-based cross-linking agent, solid content concentration 75% by mass)

As shown in Tables 4 to 6, in each of Examples 1 to 27, the viscosity of the 25% pressure-sensitive adhesive composition was as low as 8000 mPa · s or less, but the peel strength at 80 ° C. with respect to the ABS plate was 10 N / 25 mm. The above was high, and the adhesiveness under high temperature conditions was good. Further, in Examples 1 to 27, the evaluation of the cold heat cycle characteristics and the 110 ° C. heat resistance after the decorative film was bonded was "◎", "○" or "Δ", which were good. In particular, Examples 10 to 27 containing the cross-linking agent improved the peel strength at 80 ° C., the thermal cycle characteristics and the heat resistance at 110 ° C. with respect to the ABS plate, and showed excellent characteristics.

On the other hand, Comparative Examples 1 and 2 containing no vinyl polymer (C) having a Tg of 30 to 200 ° C. and a Mn of 500 to 10,000, and Comparative Example 3 in which the Mn of the vinyl polymer was larger than 10,000. In Comparative Example 4 in which the Tg of the vinyl polymer was less than 30 ° C., the peel strength at 80 ° C. with respect to the ABS plate was lower than that in Examples 1 to 27. Further, in Comparative Examples 1 to 4, both the thermal cycle characteristics and the 110 ° C. heat resistance were evaluated as “x”.
Further, in Comparative Examples 5 to 8 in which the random copolymer was contained instead of the block copolymer, at least one of the cold cycle characteristics and the heat resistance at 110 ° C. was evaluated as "x".

From the above results, according to the pressure-sensitive adhesive composition of the present disclosure, a pressure-sensitive adhesive layer having high adhesiveness under high temperature conditions and high heat resistance and durability against temperature changes is formed while reducing the viscosity. It became clear that it could be done.

Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to the examples. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms containing only one element, more, or less, are within the scope and scope of the present disclosure.

Claims

A block copolymer having a polymer block (A) and a (meth) acrylic polymer block (B),
Vinyl polymer (C) and
Contains,
The vinyl polymer (C) has a glass transition temperature of 30 ° C. or higher and 200 ° C. or lower, and a number average molecular weight of 500 or higher and 10,000 or lower.
A pressure-sensitive adhesive composition for a decorative film, wherein the content of the vinyl polymer (C) is 0.5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the block copolymer.
The polymer block (A) is a polymer having a glass transition temperature of 100 ° C. or higher.
The pressure-sensitive adhesive composition for a decorative film according to claim 1, wherein the (meth) acrylic polymer block (B) is a polymer having a glass transition temperature of −50 ° C. or higher and −10 ° C. or lower.
The polymer block (A) according to claim 1 or 2, wherein the polymer block (A) contains at least one selected from the group consisting of a structural unit derived from an aromatic vinyl compound and a structural unit derived from an imide group-containing vinyl compound. Adhesive composition for decorative films.
The pressure-sensitive adhesive composition for a decorative film according to any one of claims 1 to 3, wherein the block copolymer has a weight average molecular weight of 200,000 or more and 700,000 or less.
The decoration according to any one of claims 1 to 4, wherein the block copolymer has a molecular weight distribution (Mw / Mn) represented by a ratio of a weight average molecular weight to a number average molecular weight of 3.5 or less. Adhesive composition for films.
The pressure-sensitive adhesive composition for a decorative film according to any one of claims 1 to 5, further containing a cross-linking agent.
The vinyl polymer (C) has a glass transition temperature of 40 ° C. or higher and 140 ° C. or lower, and a number average molecular weight of 1,000 or higher and 9,500 or lower, according to any one of claims 1 to 6. The pressure-sensitive adhesive composition for a decorative film described.
The item according to any one of claims 1 to 7, wherein the content of the vinyl polymer (C) is 0.5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the block copolymer. Adhesive composition for decorative films.
The (meth) acrylic polymer block (B) contains structural units derived from the (meth) acrylic acid alkoxyester compound with respect to all the monomer units of the (meth) acrylic polymer block (B). The pressure-sensitive adhesive composition for a decorative film according to any one of claims 1 to 8, which comprises 20% by mass or more and 99% by mass or less.
A decorative film comprising an adhesive layer comprising the adhesive composition for a decorative film according to any one of claims 1 to 9.
A decorative molded body to which the decorative film according to claim 10 is attached to the molded body.