JP2013018933A - Block copolymer for adhesive, adhesive composition and surface protection film provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a block copolymer for an adhesive, an adhesive composition and a surface protection film, which are excellent in balance of adhesion and adhesive force, can retain adhesive force for a long time, exhibit practically-good adhesion even under low temperature conditions, and leave no adhesive residue.SOLUTION: The block copolymer for an adhesive has: a polymer block consisting mainly of at least two vinyl aromatic monomer units; and a polymer block consisting mainly of at least one hydrogenated conjugated diene monomer unit, and satisfies the following conditions (1) to (4). The adhesive composition comprises the copolymer and a tackifier. The surface protection film is provided with them. (1) The content of the vinyl aromatic monomer units is 15-30 mass%. (2) The vinyl bonding amount of the conjugated diene monomer unit before hydrogenation is 30-45%. (3) The rate of hydrogenation of double bond originating in the conjugated diene-based monomer is 60-90%. (4) The peak molecular weight of the block copolymer for an adhesive, which is measured by gel permeation chromatography (GPC), is 50,000-150,000.

Description

  The present invention relates to a block copolymer for adhesives, an adhesive composition, and a surface protective film comprising the same.

Conventionally, as the adhesive used for the adhesive layer of the surface protective film, rubber adhesives mainly composed of acrylic adhesive, natural rubber, polyisobutylene and other rubber have been mainly used. ing.
When these adhesives are applied to a predetermined support film, a method of applying an adhesive solution obtained by dissolving the adhesive in a solvent using a roll, a spray or the like is used. . This method has the merit that the adhesive layer can be applied uniformly and thinly, but the use of the solvent is from the viewpoint of air pollution, fire, safety and hygiene at the time of production, economy, etc. Is not preferred.

  On the other hand, as a technology for producing a hot-melt type surface protective film that does not use a solvent, a technology for producing a laminate of an adhesive layer and a support film by coextrusion is known. Various hot-melt adhesives have been developed (see, for example, Patent Document 1).

  In addition, as an adhesive having excellent adhesive strength, it consists of a block mainly composed of a vinyl aromatic compound and a block mainly composed of a conjugated diene, and hydrogenates part of the double bond of the conjugated diene part, An adhesive composition comprising an epoxy-modified hydrogenated block copolymer obtained by epoxidizing a part of the remaining double bond has been proposed (see, for example, Patent Document 2).

  Further, when an olefin resin film that is a representative of a difficult-to-adhere material is used as the support film, a copolymer having a high affinity with the olefin resin film and having ethylene as a main component, such as EVA (ethylene-acetic acid). A coextruded film using a vinyl copolymer) as an adhesive layer has been proposed (for example, see Patent Document 3).

Japanese Patent No. 4115791 JP-A-8-73699 Japanese Patent Publication No.7-116410

However, as in Patent Document 1, in the technique for producing a surface protective film by coextrusion of a laminate of an adhesive layer and a support film, the adhesive force between the support film and the adhesive layer Since it is difficult to perform corona treatment, alkali treatment, flame treatment, etc., which are effective means for improving the surface of the support film surface, it is difficult to obtain a co-extruded film having a strong adhesive force. Have.
Specifically, when a laminate of a support film and an adhesive layer is attached to a metal plate, interfacial peeling occurs between the support film and the adhesive layer, resulting in adhesive residue There is a problem that it is easy to do.

Moreover, the adhesive composition disclosed in Patent Document 2 is severely gelled or deteriorated by heating or long-term storage, and has a problem to be solved regarding long-term stability.
Further, in Patent Document 3, for example, an adhesive layer using an ABA (A is a styrene polymer block and B is an ethylene / butylene copolymer block) block copolymer is used as an olefin resin. There is also a disclosure of an adhesive film for surface protection formed on a film, but with this adhesive, good adhesion is obtained when the adherend is distorted or has a complicated shape. However, when it is attached to a smooth adherend on the other hand, the adhesive strength changes due to storage for a long time, and there is a problem that an adhesive residue is generated when the film is peeled off.

When the surface protective film has too high adhesiveness, adhesive residue tends to be generated on the adherend when the film is peeled off after application, and if it is too low, workability is poor.
Further, if the adhesive strength is too high, a large force is required when peeling off, the workability is inferior, and if it is too low, the problem of peeling during storage occurs, which is not preferable.
Furthermore, it is preferable from the viewpoint of workability that the adhesiveness in a low temperature environment and the adhesive strength after long-term storage do not change.

  Therefore, in the present invention, it is excellent in the balance between adhesiveness and adhesive strength, and the adhesive strength does not change even if the adhesive is kept in contact for a long time, and stable adhesiveness is maintained for a long time. Furthermore, it is intended to provide a block copolymer for adhesives that exhibits the same degree of tackiness as room temperature conditions even under low temperature conditions, its adhesive composition, and a surface protective film comprising these. It was aimed.

As a result of intensive studies to solve the above problems, the present inventors have found that the content of the vinyl aromatic monomer unit, the vinyl bond amount of the conjugated diene monomer unit before hydrogenation, the hydrogen of the conjugated diene moiety. By using a block copolymer in which the addition rate and the peak molecular weight of the block copolymer are in a specific range, the adhesive force is excellent in the balance between adhesiveness and adhesive force and can be maintained without changing the adhesive force even if it is adhered for a long time. We found a block copolymer for adhesives and an adhesive composition that showed the same level of tackiness at low temperature conditions as at room temperature conditions, and did not remain glued on the adherend even if the surface protective film was peeled off. The invention has been completed.
That is, the present invention is as follows.

[1]
A polymer block mainly comprising at least two vinyl aromatic monomer units;
A block copolymer for an adhesive having a polymer block mainly composed of at least one conjugated diene monomer unit hydrogenated,
The block copolymer for adhesives which comprises the conditions of following (1)-(4).
(1) The content of vinyl aromatic monomer units is 15 to 30% by mass.
(2) The vinyl bond content of the conjugated diene monomer unit before hydrogenation is 30 to 45%.
(3) The hydrogenation rate of the double bond derived from the conjugated diene monomer is 60 to 90%.
(4) The peak molecular weight measured by gel permeation chromatography (GPC) of the block copolymer for adhesives is 5 to 150,000.
[2]
The block copolymer for adhesives according to [1]: 100 parts by mass;
Tackifier: More than 0 parts by weight and 200 parts by weight or less,
An adhesive composition containing
[3]
Surface protective film comprising an adhesive layer in which the block copolymer for adhesives according to [1] or the adhesive composition according to [2] is laminated on a base film. .

  According to the present invention, it is excellent in the balance between adhesiveness and adhesive strength, and can be maintained without changing the adhesive strength even if it is kept in close contact for a long time. Then, a block copolymer for an adhesive that does not remain on the adherend even if the surface protective film is peeled off, an adhesive composition thereof, and a surface protective film comprising the same are obtained.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail.
In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

[Block copolymer for adhesives]
The block copolymer for an adhesive of this embodiment comprises a polymer block mainly composed of at least two vinyl aromatic monomer units and at least one conjugated diene monomer unit hydrogenated. It is a block copolymer for adhesives having a polymer block as a main component and satisfying the following conditions (1) to (4).
(1) The content of vinyl aromatic monomer units is 15 to 30% by mass.
(2) The vinyl bond content of the conjugated diene monomer unit before hydrogenation is 30 to 45%.
(3) The hydrogenation rate of the double bond derived from the conjugated diene monomer is 60 to 90%.
(4) The peak molecular weight measured by gel permeation chromatography (GPC) of the block copolymer is 5 to 150,000.

In addition, in this embodiment, the naming of each monomer unit which comprises a block copolymer shall follow the naming of the monomer from which the said monomer unit derives.
For example, “vinyl aromatic monomer unit” means a structural unit of a polymer resulting from polymerization of a vinyl aromatic compound as a monomer, and the structure thereof is substituted ethylene derived from a substituted vinyl group. It is a molecular structure in which the two carbons of the group are binding sites.
The term “conjugated diene monomer unit” means a structural unit of a polymer produced as a result of polymerizing a monomer, conjugated diene, and its structure is the same as that of an olefin derived from a conjugated diene monomer. It is a molecular structure in which two carbons are binding sites.
In the present specification, “mainly” means that the polymer block contains 60% by mass or more of monomer units. It is preferable to contain 80% by mass or more of monomer units, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

Examples of the “vinyl aromatic monomer” include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, And vinyl aromatic compounds such as N-diethyl-p-aminoethylstyrene. These may be used alone or in combination of two or more.
The “conjugated diene” is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1, Examples include 3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. In particular, 1,3-butadiene and isoprene are preferable. These may be used alone or in combination of two or more.
When 1,3-butadiene and isoprene are used, it is preferable that 1,3-butadiene is mainly used from the viewpoint of obtaining high mechanical strength in the adhesive composition in the present embodiment. The 1,3-butadiene content in the conjugated diene is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.

As described above, the block copolymer for an adhesive of the present embodiment includes a polymer block mainly composed of at least two vinyl aromatic monomer units, and at least one conjugated diene hydrogenated. And a polymer block mainly composed of monomer units.
If there is only one polymer block mainly composed of vinyl aromatic monomer units, the adhesiveness will be too high. If the film is peeled off after sticking, the adhesive will remain on the adherend and the adhesive strength will be insufficient. It becomes. From the viewpoint of productivity, the number of polymer blocks mainly composed of vinyl aromatic monomer units is preferably two.
The block copolymer for an adhesive of the present embodiment includes a polymer block (S) mainly composed of vinyl aromatic monomer units and a heavy polymer composed mainly of conjugated diene monomer units that are partially hydrogenated. It is preferably a block copolymer consisting of a combined block (B) and having a structure of SBS.

The block copolymer for adhesives of this embodiment may have a functional group-containing atomic group.
Examples of the functional group include a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group, and a sulfonic acid. Group, sulfonate group, phosphate group, phosphate group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfide group, isocyanate group, isothiocyanate group, silicon halide Group, alkoxysilicon group, tin halide group, boronic acid group, boron-containing group, boronate group, alkoxytin group, phenyltin group and the like.

Content of the vinyl aromatic monomer unit of the block copolymer for adhesives of this embodiment is the range of 15-30 mass%, The range of 15-25 mass% is preferable, 17-23 mass % Range is more preferred.
When content of a vinyl aromatic monomer unit exceeds 30 mass%, the adhesiveness of an adhesive composition falls. On the other hand, if it is less than 15% by mass, the tackiness becomes too high, and if the film is peeled off after sticking, an adhesive residue tends to be formed on the adherend and the coating property is also inferior.
Content of the vinyl aromatic monomer unit of the block copolymer for adhesives of this embodiment can be measured by the method described in the Example mentioned later.

The microstructure of the conjugated diene monomer unit constituting the block copolymer for adhesives of this embodiment is such that the vinyl bond content is in the range of 30 to 45% before hydrogenation. The vinyl bond amount is preferably in the range of 32 to 43%, and more preferably in the range of 33 to 41%.
The vinyl bond amount is 1,2-bond among conjugated diene monomer units incorporated in the block copolymer in a 1,2-bond, 3,4-bond and 1,4-bond bond mode. The percentage of those incorporated in the bond and 3,4-bond mode.
When the vinyl bond amount of the conjugated diene monomer unit before hydrogenation is less than 30%, the tackiness of the block copolymer for adhesive and the adhesive composition becomes too high, and the surface protective film is formed. Adhesive residue tends to occur on the adherend when it is peeled off after application. Moreover, the adhesive force of the block copolymer for adhesives and an adhesive composition becomes inadequate. On the other hand, when the vinyl bond amount of the conjugated diene monomer unit before hydrogenation exceeds 45%, the tackiness of the resulting block copolymer for adhesives and the adhesive composition is inferior.
The microstructure of the conjugated diene monomer unit can be analyzed by an infrared spectrophotometer (IR), a nuclear magnetic resonance apparatus (NMR), or the like. Specifically, it can be analyzed by the method described in Examples described later.

In the block copolymer for adhesives of this embodiment, the hydrogenation rate of the double bond derived from the conjugated diene monomer is in the range of 60 to 90%, and the range of 65 to 85%. Preferably, the range of 70 to 80% is more preferable.
When the hydrogenation rate of the conjugated diene portion is less than 60%, the adhesive strength of the block copolymer for adhesives and the adhesive composition becomes insufficient, resulting in poor coating properties. When it exceeds 90%, the tackiness of the block copolymer for adhesives and the adhesive composition becomes insufficient. The hydrogenation rate of the conjugated diene moiety can be controlled by adjusting the amount of the hydrogenation catalyst described later.
The hydrogenation rate of the conjugated diene moiety can be measured by the method described in the examples described later.

The peak molecular weight measured by gel permeation chromatography (GPC) of the block copolymer for adhesives of this embodiment is in the range of 5 to 150,000, preferably 6 to 130,000, and preferably 7 to 120,000. A range is more preferred.
When the peak molecular weight is less than 50,000, the adhesive strength of the block copolymer for adhesive and the adhesive composition becomes insufficient, and when it exceeds 150,000, the melt viscosity becomes high and the coating property deteriorates. To do.
Specifically, the peak molecular weight of the block copolymer for adhesives can be measured by the method shown in the Examples described later.

[Method for producing block copolymer for adhesive]
The method for producing the block copolymer for an adhesive of the present embodiment is not particularly limited, and for example, any polymerization method such as coordination polymerization, anionic polymerization, or cationic polymerization can be applied.
Anionic polymerization is preferred from the viewpoint of easy control of the structure.
A known method can be applied as a method for producing a block copolymer by anionic polymerization. For example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17879, Japanese Patent Publication No. 46-32415, Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 48-4106, Examples thereof include the methods described in JP-B-56-28925, JP-A-59-166518, JP-A-60-186777, and the like.
As a method of hydrogenating the conjugated diene portion of the block copolymer for adhesives of this embodiment, there is a method of supplying hydrogen in the presence of a hydrogenation catalyst and hydrogenating an unsaturated portion.
The hydrogenation catalyst is not particularly limited, but is a conventionally known hydrogenation catalyst. (1) A supported type in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like. A heterogeneous hydrogenation catalyst, (2) a so-called Ziegler-type hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, Cr or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum; ) Homogeneous hydrogenation catalysts such as so-called organometallic complexes such as organometallic compounds such as Ti, Ru, Rh and Zr.
Specifically, JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041 And hydrogenation catalysts described in Japanese Patent Publication No.

[Adhesive composition]
(Constitution)
The adhesive composition of this embodiment contains the above-mentioned block copolymer for adhesives: 100 parts by mass, and a tackifier described later: more than 0 parts by mass and 200 parts by mass or less. If necessary, it contains other components described later.

(Tackifier)
The tackifier constituting the adhesive composition of the present embodiment is not particularly limited, and examples thereof include rosin terpene resins, hydrogenated rosin terpene resins, coumarone resins, and phenol resins. And known tackifiers such as terpene-phenolic resins, aromatic hydrocarbon resins, and aliphatic hydrocarbon resins.
A tackifier may be used independently and may be used in mixture of 2 or more types.
As specific examples of the tackifier, those described in “Rubber / Plastic Compounding Chemicals” (edited by Rubber Digest Co., Ltd.) can be used.
By using a tackifier, the adhesive force can be improved.
Content of the tackifier in the adhesive composition of this embodiment is more than 0 mass part and 200 mass parts or less when the block copolymer for adhesives mentioned above is 100 mass parts. And preferably in the range of 10 to 100 parts by weight.
When the content of the tackifier exceeds 200 parts by mass, the adhesive strength after long-term pasting becomes too strong, and an adhesive residue tends to be generated at the time of peeling, which is not preferable.

(Other additives)
<Hydrogenated styrene elastomer>
The adhesive composition of the present embodiment may further contain a hydrogenated styrene-based elastomer other than the block copolymer of the present embodiment described above.
The hydrogenated styrene-based elastomer is not particularly limited, and examples thereof include styrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene (SEBS) obtained by saturation of styrene-isoprene-styrene by hydrogenation, and styrene-ethylene. -Propylene-styrene (SEPS) is a typical hydrogenated styrene elastomer, but may be an elastomer having a structure such as styrene-ethylene-butylene (SEB) or styrene-ethylene-propylene (SEP).
In addition, the hydrogenated styrene elastomer has a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group. Sulfonic acid group, sulfonic acid ester group, phosphoric acid group, phosphoric acid ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfide group, isocyanate group, isothiocyanate group, Reactive elastomers with functional groups, which have a halogenated silicon group, an alkoxysilicon group, a halogenated tin group, a boronic acid group, a boron-containing group, a boronate group, an alkoxytin group, and a phenyltin group, may be used. .

<Ethylene vinyl acetate copolymer>
The adhesive composition of this embodiment may further contain an ethylene vinyl acetate copolymer.
The ethylene vinyl acetate copolymer is not particularly limited, and can be produced, for example, by radical copolymerization of ethylene and vinyl acetate under high temperature and high pressure conditions. The ethylene vinyl acetate copolymer has different properties depending on the vinyl acetate content, but is not particularly limited.

<Acrylic copolymer>
The composition for adhesives of this embodiment may further contain an acrylic copolymer.
The acrylic copolymer is not particularly limited, and examples thereof include copolymers of methyl acrylate, ethyl acrylate, methyl methacrylate, acrylonitrile with vinyl acetate, vinyl chloride, styrene, and the like.

<Softener>
The adhesive composition of this embodiment may further contain a softening agent.
As the softener, either a mineral oil softener or a synthetic resin softener can be used.
The mineral oil softener generally includes a mixture of aromatic hydrocarbon, naphthene hydrocarbon, and paraffin hydrocarbon, and the number of carbon atoms of the paraffin hydrocarbon is 50% or more of all carbon atoms. Is called paraffinic oil, naphthenic hydrocarbons having 30 to 45% carbon atoms are called naphthenic oils, and aromatic hydrocarbons having 35% or more carbon atoms. It is called aromatic oil.
As the mineral oil softener, paraffin oil which is a softener for rubber is preferable, and as the synthetic resin softener, polybutene, low molecular weight polybutadiene and the like are preferable.
By containing the softening agent, the tackiness of the adhesive composition of this embodiment is improved.
The content of the softener in the adhesive composition of the present embodiment is the above-mentioned from the viewpoint of suppressing bleeding of the softener and ensuring practically sufficient adhesive strength in the adhesive composition of the present embodiment. It is preferable that it is 0-100 mass parts, when the block copolymer for adhesive agents made 100 mass parts.

<Antioxidants, light stabilizers, etc.>
You may further add stabilizers, such as antioxidant and a light stabilizer, to the adhesive composition of this embodiment.
Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, 2 , 2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,4-bis [(octylthio) methyl] -o-cresol 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- [1- (3 , 5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl)] acrylate, and the like. Antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate pentaerythritol-tetrakis (β-lauryl thiopropionate); tris (nonylphenyl) phosphite, tris ( And phosphorus-based antioxidants such as 2,4-di-t-butylphenyl) phosphite.
Examples of the light stabilizer include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) benzotriazole, 2- (2 Benzotriazole ultraviolet absorbers such as '-hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, benzophenone ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone, or hindered amines System light stabilizers and the like.

<Pigments, waxes, thermoplastic resins, natural rubber, synthetic rubber>
In addition, the adhesive composition of the present embodiment includes, if necessary, pigments such as Bengala and titanium dioxide; waxes such as paraffin wax, microcrystalline wax, and low molecular weight polyethylene wax; amorphous polyolefin, ethylene Polyolefin or low molecular weight vinyl aromatic thermoplastic resins such as ethyl acrylate copolymer; natural rubber; polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene Synthetic rubber such as rubber and polypentenamer rubber may be added. Other examples of the synthetic rubber include those described in “Rubber / Plastic Compounding Chemicals” (edited by Rubber Digest Co., Ltd.).

[Method for producing adhesive composition]
The adhesive composition of this embodiment can be produced by a conventionally known method.
For example, a melt kneading method using a general mixer such as a Banbury mixer, a single screw extruder, a twin screw extruder, a kneader, a multi-screw extruder, etc. A method of removing the solvent by heating after coating on the Kizai film is used.
The adhesive composition of this embodiment may be subjected to a foaming treatment in order to achieve an effect of improving weight reduction, softening, and adhesion. Examples of the foaming method include a chemical method, a physical method, and use of a thermal expansion type microballoon. In each case, bubbles can be distributed inside the material by adding a chemical foaming agent such as an inorganic foaming agent or an organic foaming agent, a physical foaming agent or the like, or adding a thermal and thermal expansion type microballoon.
Moreover, you may aim at weight reduction, softening, and the improvement of adhesiveness by adding a hollow filler (already inflated balloon).

[Surface protection film]
The surface protective film of the present embodiment comprises an adhesive layer obtained by laminating the above-mentioned block copolymer for an adhesive or the adhesive composition of the present embodiment on a predetermined substrate film. It has the composition to comprise.
As the material for the base film, either a nonpolar resin or a polar resin can be used, but from the viewpoint of performance and price, the nonpolar resin is polyethylene, homo- or block polypropylene, the polar resin is polyethylene terephthalate, Preferred examples include polyester resins such as polybutylene terephthalate, polyamide resins, ethylene-vinyl acetate copolymers and hydrolysates thereof.
The thickness of the adhesive layer constituting the surface protective film of the present embodiment is preferably 1 μm or more and 100 μm or less, and more preferably 5 to 100 μm.
When the thickness of the adhesive layer exceeds 100 μm, the capacity becomes large, the handleability deteriorates, and it is economically disadvantageous. In addition, when the thickness is less than 1 μm, the adhesiveness is deteriorated and a uniform thickness cannot be obtained.
The thickness of the base film is preferably 5 mm or less, more preferably 3 mm or less, still more preferably 1 mm or less, even more preferably 300 μm or less, and even more preferably 10 to 200 μm.
In general, a film having a thickness exceeding 300 μm is referred to as a “sheet”, but in the present specification, it is described as a film including these.

[Method for producing surface protective film]
Examples of the method for producing a surface protective film in the present embodiment include a method of coating a block copolymer for an adhesive or a solution of an adhesive composition, or a melt on the base film, and a film. The method using an extruder is mentioned.
In the method of coating the solution of the block copolymer for adhesive or the adhesive composition, dissolve it in a soluble solvent, apply it on the base film using a coater, and heat the solvent. It can be manufactured by drying.
In the method of melting and coating the adhesive block copolymer or adhesive composition, using a hot melt coater or the like, the adhesive block copolymer melted on the base film or It can manufacture by applying an adhesive composition. In this case, various base films having a glass transition temperature, a melting point or a softening point higher than the coating temperature are used.
As a method using a film extruder, a block copolymer for an adhesive or a layer of an adhesive composition and a thermoplastic resin component of a base film layer are separated into two by a melt co-extruder. In a flow, that is, the adhesive layer forming fluid and the base body film forming fluid are merged in the die mouth to form a single fluid, and the adhesive layer and the resin film layer are extruded. It is manufactured by combining.
In the case of the method using a film extruder, the block copolymer or adhesive composition for an adhesive is dry-blended with each component of the block copolymer for adhesive or the adhesive composition in advance. Therefore, it is a method with excellent productivity.

  Hereinafter, the present invention will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

First, evaluation methods and physical property measurement methods applied to Examples and Comparative Examples are shown below.
[I. (Evaluation of composition and structure of block copolymer)
(I-1) Styrene content, vinyl bond amount of conjugated diene, hydrogenation rate of double bond based on conjugated diene Styrene content in polymer, vinyl bond amount of conjugated diene, hydrogen of double bond based on conjugated diene The addition rate was measured under the following conditions by nuclear magnetic resonance spectrum analysis (NMR).
Measuring instrument: JNM-LA400 (manufactured by JEOL)
Solvent: Deuterated chloroform Measurement sample: Extracted product before or after hydrogenation of polymer Sample concentration: 50 mg / mL
Observation frequency: 400 MHz
Chemical shift criteria: TMS (tetramethylsilane)
Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45 °
Measurement temperature: 26 ° C

(I-2) Peak molecular weight It measured by gel permeation chromatography (GPC) on the following conditions, and calculated | required from molecular weight from the PS conversion calibration curve in the obtained peak.
Measuring device: GPC HLC-8220 (manufactured by TOSOH, trade name)
Column: TAKgelGMHXL SuperH5000: 1, SuperH4000: 2 (trade name, manufactured by TOSOH)
Solvent: Tetrahydrofuran Temperature: 40 ° C
Calibration curve sample: commercially available standard sample (manufactured by TOSOH), 10-point measurement

[II. Characteristics of block copolymer for adhesive and adhesive composition)
(II-1) Coating property The coating property with a small automatic film applicator was visually observed. The coatability was evaluated according to the following criteria.
○: The surface state of the adhesive layer was uniform.
Δ: The surface of the adhesive layer was slightly rough.
X: The surface of the adhesive layer was considerably rough.

(II-2) Adhesiveness As a measuring device, probe tack tester NTS-4800: manufactured by Tester Sangyo Co., Ltd. was used.
The surface protective films produced in Examples 1 to 5 and Comparative Examples 1 to 10 below were attached to a bobbin on which a double-sided tape with a weight of 10 g was attached, and the temperature was 23 ° C., CONACT SPEED and PEELING SPEED were 1.0 cm / second. The measurement was performed under the condition of a contact time of 5 seconds.
Moreover, the adhesiveness at low temperature was measured under the conditions of a temperature of 0 ° C. and a contact time of 5 seconds without changing SPEED.
In addition, the value of adhesiveness read the maximum value of the data detected from the probe tack tester NTS-4800.

(II-3) Adhesive strength (g / 10 mm)
As a measuring apparatus, a universal tensile testing machine “Tensilon STM-T-200BP: manufactured by Orientec Co., Ltd.” was used.
A surface protective film prepared in Examples 1 to 5 and Comparative Examples 1 to 10 below was attached to a PMMA plate (polymethyl methacrylate plate: arithmetic average roughness of the surface: 0.1 μm), and 180 ° C. at a temperature of 23 ° C. Two types of peeling tests were performed immediately after sticking and after long-term adhesion.
In the 180 degree peeling test, the surface protective film as a measurement sample was applied to a PMMA plate with a width of 25 mm, and the peeling force was measured at a peeling speed of 300 mm / min.
In addition, the evaluation of long-time adhesion was measured after pasting the surface protective film prepared in Examples 1 to 5 and Comparative Examples 1 to 10 below on a PMMA plate and leaving it at 23 ° C. and 50% relative humidity for 14 days. did.

(II-4) Adhesive residue A surface protective film prepared in the following Examples and Comparative Examples was attached to a PMMA plate (arithmetic average roughness of surface: 1.1 μm), and in a relative humidity of 23 ° C. × 50%. A rubber roll having a weight of 1 kg (diameter 10 cm) was rolled and pasted, and then left for 14 days under a temperature condition of 23 ° C. Thereafter, the surface protective film was peeled off, and the state of the adhesive residue on the PMMA plate was evaluated.
In Tables 1 to 3 below, the adhesive residue was evaluated in three stages of ◯, ×, and XX.
I will show you these evaluation criteria.
A: The adhesive residue that can be visually observed with respect to the peeled area (1 m ² ) is 0 to 1 point.
X: The adhesive residue which can be visually observed with respect to a peeling area (1m < ² >) is a thing of 2-4 points | pieces.
Xx: The adhesive residue which can be visually observed with respect to a peeling area (1 m < ² >) is 5 or more points | pieces.

[III. Preparation of hydrogenation catalyst)
The hydrogenation catalyst used for the hydrogenation reaction of the block copolymer was prepared by the following method.
Charge 1 liter of dried and purified cyclohexane to a nitrogen-substituted reaction vessel, add 100 mmol of biscyclopentadienyl) titanium dichloride, and add an n-hexane solution containing 200 mmol of trimethylaluminum while stirring thoroughly. The mixture was reacted at room temperature for about 3 days to prepare a hydrogenation catalyst.

[IV. Preparation of block copolymer)
<Polymer 1: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
Here, A1, A2, B1, and B2 each represent the following polymer block.
A1, A2: Polystyrene polymer block B1: Partially hydrogenated product of polybutadiene copolymer block The internal volume is 10L, and the stirred apparatus and jacketed tank reactor are washed, dried, and purged with nitrogen. Batch polymerization was performed.
First, a cyclohexane solution (concentration 20% by mass) containing 10 parts by mass of styrene was added.
Next, 0.042 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers, and N, N, N ′, N′-tetramethylethylenediamine (hereinafter referred to as “TMEDA”) are n-butyl. 0.5 mol was added to 1 mol of lithium and polymerized at 70 ° C. for 15 minutes.
Thereafter, a cyclohexane solution (concentration 20% by mass) containing 80 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution (concentration 20% by mass) containing 10 parts by mass of styrene was added and polymerized at 75 ° C. for 20 minutes.
The polymer obtained as described above had a styrene content of 20% by mass, a vinyl bond content of 40% in the polybutadiene portion, and a peak molecular weight of 100,000 in the polymer.
Next, 77 ppm of the hydrogenation catalyst prepared according to the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction is performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the polymer.
The resulting block copolymer (Polymer 1) had a butadiene hydrogenation rate of 75%.

<Polymer 2: Hydrogenated product of styrene-partially hydrogenated butadiene-styrene (A1-B1-A2-B2)>
Similarly to the synthesis of Polymer 1, the stirring apparatus and jacketed tank reactor having an internal volume of 10 L were washed, dried, and purged with nitrogen, and batch polymerization was performed by the following method.
A cyclohexane solution (concentration 20% by mass) containing 14 parts by mass of styrene was added. Next, 0.062 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.45 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 20 minutes.
Thereafter, a cyclohexane solution (concentration: 20% by mass) containing 67 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes. Furthermore, a cyclohexane solution containing 14 parts by mass of styrene was added and polymerized at 75 ° C. for 20 minutes.
Finally, a cyclohexane solution containing 5 parts by mass of butadiene was added and polymerized at 70 ° C. for 30 minutes.
The polymer obtained as described above had a styrene content of 28% by mass, a vinyl bond content of polybutadiene part of 35%, and a peak molecular weight of 70,000.
Next, to the polymer obtained as described above, the hydrogenation catalyst prepared according to the above (III) was added in an amount of 82 ppm as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction was performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the polymer.
The resulting hydrogenated block copolymer (Polymer 2) had a butadiene hydrogenation rate of 80%.

<Polymer 3: Styrene-partially hydrogenated butadiene (A1-B1)>
Similarly to the synthesis of the polymer 1, a stirring apparatus and a jacketed tank reactor having an internal volume of 10 L were washed, dried, and purged with nitrogen, and batch polymerization was performed by the following method.
First, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of styrene was added.
Next, 0.041 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.5 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 25 minutes.
Thereafter, a cyclohexane solution (concentration: 20% by mass) containing 75 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes.
The polymer obtained as described above had a styrene content of 25% by mass, a vinyl bond content of 40% in the polybutadiene portion, and a peak molecular weight of 100,000.
Next, to the polymer obtained as described above, the hydrogenation catalyst prepared according to the above (III) was added in an amount of 82 ppm as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction was performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the polymer.
The resulting block copolymer (Polymer 3) had a butadiene hydrogenation rate of 80%.

<Polymer 4: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
Similarly to the synthesis of the polymer 1, a stirring apparatus and a jacketed tank reactor having an internal volume of 10 L were washed, dried, and purged with nitrogen, and batch polymerization was performed by the following method.
A cyclohexane solution (concentration 20% by mass) containing 5 parts by mass of styrene was added.
Next, 0.034 parts by mass of n-butyl lithium with respect to 100 parts by mass of all monomers and 0.5 mol of TMEDA with respect to 1 mol of n-butyl lithium were added and polymerized at 70 ° C. for 15 minutes.
Thereafter, a cyclohexane solution (concentration: 20% by mass) containing 90 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution containing 5 parts by mass of styrene (concentration: 20% by mass) was added and polymerized at 75 ° C. for 20 minutes.
The polymer obtained as described above had a styrene content of 10% by mass, a vinyl bond content of 40 mol% in the polybutadiene portion, and a peak molecular weight of the polymer of 120,000.
Next, 77 ppm of the hydrogenation catalyst prepared according to the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction is performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the polymer.
The resulting block copolymer (Polymer 4) had a butadiene hydrogenation rate of 75%.

<Polymer 5: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
First, a cyclohexane solution (concentration 20% by mass) containing 17.5 parts by mass of styrene was added.
Next, 0.041 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.45 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 20 minutes.
Next, a cyclohexane solution containing 20 parts by mass of butadiene (concentration 20% by mass) was added and polymerization was carried out at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution (concentration 20% by mass) containing 17.5 parts by mass of styrene was added and polymerized at 75 ° C. for 25 minutes to obtain a polymer.
The polymer obtained as described above had a styrene content of 35% by mass, a vinyl bond content of 35% in the polybutadiene portion, and a peak molecular weight of 100,000 in the polymer.
Other conditions were hydrogenated in the same manner as in Polymer 1, and methanol and a stabilizer were added to obtain Polymer 5.
The resulting block copolymer (Polymer 5) had a butadiene hydrogenation rate of 75%.

<Polymer 6: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
First, a cyclohexane solution (concentration 20% by mass) containing 12 parts by mass of styrene was added.
Next, 0.041 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.25 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 15 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 76 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution containing 12 parts by mass of styrene (concentration: 20% by mass) was added and polymerized at 75 ° C. for 20 minutes.
The polymer obtained as described above had a styrene content of 24% by mass, a vinyl bond content of polybutadiene part of 25%, and a peak molecular weight of the polymer of 100,000.
Next, 82 ppm of the hydrogenation catalyst prepared by the above (III) was added as titanium per 100 parts by mass of the polymer, hydrogenated in the same manner as in the polymer 1, methanol and a stabilizer were added, and the polymer 6 was obtained. The resulting block copolymer (Polymer 6) had a butadiene hydrogenation rate of 80%.

<Polymer 7: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
0.041 parts by mass of n-butyllithium was added to 100 parts by mass of all monomers, and 0.65 mol of TMEDA was added to 1 mol of n-butyllithium. The other conditions were polymerized in the same manner as in Polymer 1. The obtained polymer had a styrene content of 20% by mass, a vinyl bond content of 55% in the polybutadiene portion, and a peak molecular weight of 100,000 in the polymer.
Next, the polymer obtained as described above was subjected to a hydrogenation reaction in the same manner as in Polymer 1 to obtain Polymer 7.
The resulting block copolymer (Polymer 7) had a butadiene hydrogenation rate of 75%.

<Polymer 8: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
First, a cyclohexane solution (concentration 20% by mass) containing 13.5 parts by mass of styrene was added.
Next, 0.041 parts by mass of n-butyllithium was added to 100 parts by mass of all monomers, and 0.47 mol of TMEDA was added to 1 mol of n-butyllithium, followed by polymerization at 70 ° C. for 15 minutes.
Thereafter, a cyclohexane solution (concentration: 20% by mass) containing 73 parts by mass of butadiene was added and polymerized at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution (concentration 20% by mass) containing 13.5 parts by mass of styrene was added and polymerized at 75 ° C. for 20 minutes.
The polymer obtained as described above had a styrene content of 27% by mass, a vinyl bond content of 37% in the polybutadiene portion, and a peak molecular weight of 100,000 in the polymer.
Next, 66 ppm of the hydrogenation catalyst prepared by the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction is performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol and a stabilizer were added in the same manner as in Polymer 1 to obtain Polymer 8.
The resulting block copolymer (Polymer 8) had a butadiene hydrogenation rate of 65%.

<Polymer 9: Bifunctional coupling of styrene-partially hydrogenated butadiene ((A1-B1) × 2)>
Similarly to the synthesis of Polymer 1, the stirring apparatus and jacketed tank reactor having an internal volume of 10 L were washed, dried, and purged with nitrogen, and batch polymerization was performed by the following method.
First, a cyclohexane solution (concentration 20% by mass) containing 18 parts by mass of styrene was added.
Next, 0.074 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.43 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 20 minutes.
Thereafter, a cyclohexane solution (concentration 20% by mass) containing 82 parts by mass of butadiene was added, and polymerization was carried out at 75 ° C. for 85 minutes.
Next, ethyl benzoate was added, and the reaction was carried out for 10 minutes while adjusting the temperature inside the reactor to 70 ° C. to carry out a coupling reaction.
The polymer obtained as described above had a styrene content of 18% by mass, a vinyl bond content of polybutadiene part of 33%, a coupling rate of 70%, and a main peak molecular weight of the polymer of 120,000.
Next, 87 ppm of the hydrogenation catalyst prepared by the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction is performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Went.
Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the polymer.
The resulting block copolymer (Polymer 9) had a butadiene hydrogenation rate of 85%.

<Polymer 10: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
Polymerization was carried out in the same manner as in Polymer 1 except that 0.034 parts by mass of n-butyllithium was added to 100 parts by mass of all monomers. The obtained polymer had a styrene content of 20% by mass, a vinyl bond content of 40% in the polybutadiene portion, and a peak molecular weight of the polymer of 120,000.
Next, 51 ppm of the hydrogenation catalyst prepared in the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the other conditions are the same as those for the polymer 1 above. 10 was obtained.
The resulting block copolymer (Polymer 10) had a butadiene hydrogenation rate of 50%.

<Polymer 11: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
Polymerization was performed in the same manner as in Polymer 1 except that 0.041 parts by mass of n-butyllithium was added to 100 parts by mass of all monomers, and 0.45 mol of TMEDA was added to 1 mol of n-butyllithium. It was.
The polymer obtained as described above had a styrene content of 20% by mass, a vinyl bond content of the polybutadiene part of 35%, and a peak molecular weight of the polymer of 100,000.
Next, 99 ppm of the hydrogenation catalyst prepared according to the above (III) is added as titanium per 100 parts by mass of the polymer to the polymer obtained as described above, and the other conditions are the same as those of the polymer 1 described above. 11 was obtained.
The resulting block copolymer (Polymer 11) had a butadiene hydrogenation rate of 96%.

<Polymer 12: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
First, a cyclohexane solution (concentration 20% by mass) containing 12.5 parts by mass of styrene was added.
Next, 0.10 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.5 mol of TMEDA with respect to 1 mol of n-butyllithium were added and polymerized at 70 ° C. for 15 minutes.
Next, a cyclohexane solution containing 75 parts by mass of butadiene (concentration 20% by mass) was added, and polymerization was performed at 75 ° C. for 85 minutes.
Finally, a cyclohexane solution (concentration 20% by mass) containing 12.5 parts by mass of styrene was added and polymerized at 75 ° C. for 20 minutes.
The other conditions were polymerized in the same manner as for polymer 1. The resulting polymer had a styrene content of 25% by mass, a vinyl bond content of 40% in the polybutadiene portion, and a peak molecular weight of 30,000 for the polymer.
Next, 77 ppm of the hydrogenation catalyst prepared according to the above (III) is added to the polymer obtained as described above as titanium per 100 parts by mass of the polymer, and the hydrogenation reaction is performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. And methanol and stabilizer were added as in Polymer 1.
The resulting block copolymer (Polymer 12) had a butadiene hydrogenation rate of 75%.

<Polymer 13: Styrene-partially hydrogenated butadiene-styrene (A1-B1-A2)>
0.021 parts by mass of n-butyllithium was added to 100 parts by mass of all monomers, and 0.45 mol of TMEDA was added to 1 mol of n-butyllithium. The other conditions were polymerized in the same manner as in Polymer 1. The obtained polymer had a styrene content of 20% by mass, a vinyl bond content of the polybutadiene part of 35%, and a peak molecular weight of the polymer of 200,000.
Next, the polymer obtained as described above was subjected to a hydrogenation reaction in the same manner as in Polymer 1 to obtain Polymer 13.
The resulting block copolymer (Polymer 13) had a butadiene hydrogenation rate of 75%.

[Example 1]
As a block copolymer, 10 g of the above (Polymer 1) is dissolved in 40 g of toluene, and a 20% by weight toluene solution is used as a polyester film with a thickness of 38 μm using a small automatic film applicator (BYK-Gardner, model: PA-2105). Then, the polymer solution was applied, air-dried in a fume hood for 30 minutes, and then dried in a hot air dryer at 70 ° C. for 7 minutes to prepare a surface protective film having an adhesive layer.
The thickness of the adhesive layer after drying was 30 μm.
About this surface protection film, the adhesive property when the coating property and the surface protection film were peeled off was observed, and the tackiness (after 23 ° C. × 5 seconds, after 0 ° C. × 5 seconds), the adhesive strength (23 ° C. × 1) After 14 days, measurement was performed. The measurement results are shown in Table 1 below.

[Example 2]
Using (Polymer 2) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20% by weight toluene solution of Polymer 2, and each characteristic was measured. The measurement results are shown in Table 1 below.

[Comparative Example 1]
Using (Polymer 3) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20% by weight toluene solution of Polymer 3, and each characteristic was measured. The measurement results are shown in Table 1 below.

[Comparative Example 2]
Using (Polymer 4) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20% by mass toluene solution of Polymer 4, and each characteristic was measured. The measurement results are shown in Table 1 below.

[Comparative Example 3]
Using (Polymer 5) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 5, and each characteristic was measured. The measurement results are shown in Table 1 below.

[Comparative Example 4]
Using (Polymer 6) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 6, and each characteristic was measured. The measurement results are shown in Table 1 below.

[Comparative Example 5]
Using (Polymer 7) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 7, and each characteristic was measured. The measurement results are shown in Table 1 below.

Example 3
Using (Polymer 8) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 8, and each characteristic was measured. The measurement results are shown in Table 2 below.

Example 4
Using (Polymer 9) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 9, and each characteristic was measured. The measurement results are shown in Table 2 below.

[Comparative Example 6]
Using (Polymer 10) in place of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 10, and each characteristic was measured. The measurement results are shown in Table 2 below.

[Comparative Example 7]
Using (Polymer 11) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 11, and each characteristic was measured. The measurement results are shown in Table 2 below.

[Comparative Example 8]
Using (Polymer 12) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 12, and each characteristic was measured. The measurement results are shown in Table 2 below.

[Comparative Example 9]
Using (Polymer 13) instead of (Polymer 1), a surface protective film was prepared in the same manner as in Example 1 using a 20 mass% toluene solution of Polymer 13, and each characteristic was measured. The measurement results are shown in Table 2 below.

Example 5
10 g of the above (Polymer 1) was used as a block copolymer, 10 g of Alcon M-115 (Arakawa Chemical Industries, Ltd.) was used as a tackifier, and dissolved in 40 g of toluene until uniform, and the same as in Example 1 A surface protective film was prepared by the method, and each characteristic was measured. The measurement results are shown in Table 3 below.

[Comparative Example 10]
10 g of the above (Polymer 1) was used as a block copolymer, 25 g of Alcon M-115 (Arakawa Chemical Industries, Ltd.) was used as a tackifier, and dissolved in 40 g of toluene until uniform, and the same as in Example 1 A surface protective film was prepared by the method, and each characteristic was measured. The measurement results are shown in Table 3 below.

As shown in Table 1, each of Examples 1 and 2 has excellent coating properties, maintains an adhesive force for a long time, and is sufficient for both low temperature conditions and normal temperature conditions. Stickiness was obtained.
On the other hand, in Comparative Example 1, since there is only one vinyl aromatic monomer polymerization block of the block copolymer (Polymer 3), good evaluation in terms of any of adhesiveness, adhesive strength, and adhesive residue. Was not obtained.
In Comparative Example 2, since the content of the vinyl aromatic monomer unit in the block copolymer (Polymer 4) is low, it is practical in any of coating property, adhesiveness, adhesive strength, and adhesive residue. A good evaluation was not obtained.
In Comparative Example 3, since the content of the vinyl aromatic monomer unit in the block copolymer (Polymer 5) is high, a good evaluation for practical use was obtained in both adhesiveness and adhesive strength. I couldn't.
Furthermore, in Comparative Example 4 and Comparative Example 5, the block copolymer (Polymer 6, Polymer 7) has a low or high vinyl bond content in the conjugated diene monomer unit before hydrogenation. No practically good evaluation was obtained.

As shown in Table 2, each of Examples 3 and 4 has excellent coating properties, maintains an adhesive force for a long time, and is sufficient for both low temperature conditions and normal temperature conditions. Stickiness was obtained.
On the other hand, in Comparative Example 6, since the hydrogenation rate of butadiene in the block copolymer (Polymer 10) was low, the coating property was inferior, and the adhesive strength was not evaluated as being practically good.
In Comparative Example 7, since the hydrogenation rate of butadiene in the block copolymer (Polymer 11) was high, evaluation of practically good adhesion was not obtained.
In Comparative Example 8, since the peak molecular weight of the block copolymer (Polymer 12) was low, practically good evaluation of the adhesive strength could not be obtained.
In Comparative Example 9, since the peak molecular weight of the block copolymer (Polymer 13) was high, the coating property was inferior, and the adhesiveness was not evaluated as being practically good.

As shown in Table 3, in Example 5, the adhesive composition has excellent coating properties, and the adhesive strength is maintained for a long time. Also sufficient tackiness was obtained.
On the other hand, in Comparative Example 10, since the amount of the tackifier contained in the adhesive composition is large, the tackiness under low temperature conditions is low, the tackiness is too high, and the adhesive residue is poor. It was.

  The block copolymer for adhesives and the adhesive composition of the present invention are adhesives for bonding metal, glass, synthetic resin, etc., improve the scratch resistance of the surface, dust, dust, dust, etc. As a material for the adhesive layer of the surface protective film that prevents adhesion of the resin, there is industrial applicability.

Claims (3)

A polymer block mainly comprising at least two vinyl aromatic monomer units;
A block copolymer for an adhesive having a polymer block mainly composed of at least one conjugated diene monomer unit hydrogenated,
The block copolymer for adhesives which comprises the conditions of following (1)-(4).
(1) The content of vinyl aromatic monomer units is 15 to 30% by mass.
(2) The vinyl bond content of the conjugated diene monomer unit before hydrogenation is 30 to 45%.
(3) The hydrogenation rate of the double bond derived from the conjugated diene monomer is 60 to 90%.
(4) The peak molecular weight measured by gel permeation chromatography (GPC) of the block copolymer for adhesives is 5 to 150,000. The block copolymer for adhesives according to claim 1: 100 parts by mass;
Tackifier: More than 0 parts by weight and 200 parts by weight or less,
An adhesive composition containing   The surface protection film which comprises the adhesive layer which laminated | stacked the block copolymer for adhesives of Claim 1, or the adhesive composition of Claim 2 on the base film.