JP5562573B2 - Composition for pressure-sensitive adhesive and surface protective film comprising the same - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition and a surface protective film comprising the same.

Conventionally, rubber pressure-sensitive adhesives mainly composed of rubbers such as acrylic pressure-sensitive adhesives, natural rubber, and polyisobutylene have been mainly used as pressure-sensitive adhesives for surface protecting pressure-sensitive adhesive films.
When these pressure-sensitive adhesives are applied to a predetermined support film, a method of applying a pressure-sensitive adhesive solution obtained by dissolving the pressure-sensitive adhesive in a solvent using a roll, a spray or the like has been employed. This method has the advantage that the pressure-sensitive adhesive layer can be applied uniformly and thinly, but the use of a solvent is preferable from the viewpoint of air pollution, fire, safety and hygiene at the time of production, economy, etc. Absent.
As a hot-melt type manufacturing technology that does not use a solvent, a technology to manufacture a laminate of a pressure-sensitive adhesive layer and a support film by co-extrusion is known, and various hot-melt type pressure-sensitive adhesives have also been developed. (For example, refer to Patent Document 1).

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

  In addition, when an olefin resin film, which is a representative of difficult-to-adhere materials, is used as the support film, an ethylene-based copolymer having a high affinity with the olefin resin film, such as EVA, is used as an adhesive layer. A coextruded film is proposed (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 laminate of a pressure-sensitive adhesive layer and a support film by coextrusion, it is an effective means for increasing the adhesive force between the support film and the pressure-sensitive adhesive layer. Since it is difficult to perform corona treatment, alkali treatment, flame treatment and the like, there is a problem that it is difficult to obtain a coextruded film having a strong adhesive force.
Specifically, when a laminate of the support film and the pressure-sensitive adhesive layer is attached to a metal plate or the like, there is a problem that interfacial peeling occurs between the support film and the pressure-sensitive adhesive layer, and adhesive residue is likely to occur. There is.

  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.

  In addition, the coextruded film disclosed in Patent Document 3 has a problem that sufficient tackiness cannot be obtained with a very low acid vinyl content.

  Further, in Patent Document 3, for example, a pressure-sensitive adhesive layer using an ABA (A is a styrene polymer block and B is an ethylene / butylene copolymer block) block copolymer is provided on an olefin resin film. The adhesive film for surface protection formed on the surface is also disclosed, but with this pressure-sensitive adhesive, good adhesion can be obtained when the adherend is distorted or has a complicated shape. On the other hand, when it is attached to a smooth adherend, 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.

  Therefore, in the present invention, even if the adherend has a distorted shape, it can exhibit good adhesion, has an appropriate adhesion strength, and does not change the adhesion strength even if it adheres for a long time. An object of the present invention is to provide a composition for a pressure-sensitive adhesive that maintains stable adhesiveness and that exhibits a pressure-sensitive adhesive strength comparable to that at room temperature even under low temperature conditions, and a surface protective film including the same.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a pressure-sensitive adhesive composition containing a copolymer having tan δ peaks in two specific temperature ranges. Even if the body is distorted, it exhibits good adhesion, has practically sufficient adhesive strength and can maintain the adhesive strength without changing even if it adheres for a long time, and is comparable to room temperature conditions even at low temperatures The present inventors have found a pressure-sensitive adhesive composition exhibiting the above-mentioned adhesive strength and have completed the present invention.
That is, the present invention is as follows.

[1] A pressure-sensitive adhesive composition containing a copolymer (A) having a vinyl aromatic monomer unit, wherein the copolymer (A) is in a range of −70 ° C. or higher and −5 ° C. or lower. The copolymer (A) has one or more tan δ (loss tangent) peaks 1 and one or more tan δ (loss tangent) peaks 2 in the range of 0 ° C. or more and 50 ° C. or less. The composition for adhesives containing 1 or more of each block of (c) is provided.
(A) Polymer block containing 95% by mass or more of vinyl aromatic monomer unit
(B) a copolymer block containing an alkylene unit and a vinyl aromatic monomer unit or a hydrogenated copolymer block containing a conjugated diene unit and a vinyl aromatic monomer unit, Copolymer block or hydrogenated copolymer block having a content of monomer units of 55 to 90% by mass
(C) A polymer block containing 60% by mass or more of alkylene units or a hydrogenated polymer block containing 60% by mass or more of conjugated diene units

[2] The pressure-sensitive adhesive composition according to [1], wherein the copolymer (A) has a tan δ (loss tangent) at 25 ° C. of 0.10 or more.

[3] The pressure-sensitive adhesive composition according to [1] or [2] , wherein the copolymer (A) contains the following blocks (a), (b2), and (c2): .
(A) Polymer block containing 95% by mass or more of vinyl aromatic monomer unit: 10 to 50% by mass
(B2) A hydrogenated copolymer block containing a conjugated diene unit and a vinyl aromatic monomer unit, wherein the content of the vinyl aromatic monomer unit is 55 to 90% by mass. Combined block : 25-80% by mass
(C2) Hydrogenated polymer block containing 60% by mass or more of conjugated diene units: 10 to 70% by mass

[4] The pressure-sensitive adhesive composition according to [3] , wherein the copolymer (A) is a polymer in which 60 mol% or more of all conjugated diene units in the copolymer (A) are hydrogenated. Offer things.

[5] As described in any one of [1] to [4] , the copolymer (A) has a polymer block containing 95% by mass or more of a vinyl aromatic monomer unit at both terminal portions. A pressure-sensitive adhesive composition is provided.

[6] The pressure-sensitive adhesive composition according to any one of [1] to [5] , further including one or more thermoplastic resins.

[7] The above [1] to [6] further containing one or more selected from the group consisting of (B) hydrogenated styrene elastomer, (C) ethylene vinyl acetate copolymer, and (D) acrylic copolymer. ] The composition for adhesives as described in any one of these.

[8] The composition for pressure-sensitive adhesives according to [7] , containing 10% by mass to 80% by mass of the copolymer (A) and 20% by mass to 90% by mass of the (B) hydrogenated styrene elastomer. Offer things.

[9] The pressure-sensitive adhesive composition according to any one of [1] to [8] , wherein the copolymer (A) has a functional group.

[10] Provided is a surface protective film in which one or more layers of the pressure-sensitive adhesive composition according to any one of [1] to [9] having a thickness of 1 μm to 100 μm are provided on a base film.

  According to the present invention, even if the adherend is in a distorted shape, it exhibits good adhesion, has an appropriate adhesion strength, and does not change even if it adheres for a long time, so that long-term stability The composition for adhesives which is excellent in this and shows the adhesive force comparable to room temperature conditions also in low temperature conditions, and the surface protection film which comprises this are obtained.

  Hereinafter, although the form for implementing this invention (henceforth "this embodiment") is demonstrated, this invention is not limited to the form shown below.

[Adhesive composition]
The composition for adhesives of this embodiment is a composition for adhesives containing the copolymer (A) which has a vinyl aromatic monomer unit.
The copolymer (A) has at least one tan δ (loss tangent) peak 1 in the range of −70 ° C. to −5 ° C. and one or more tan δ (loss tangent) in the range of 0 ° C. to 50 ° C. ) A pressure-sensitive adhesive composition having a peak 2.

((A) Copolymer having vinyl aromatic monomer unit)
(A) The copolymer having a vinyl aromatic monomer unit has one or more tan δ peaks 1 in a range of −70 ° C. or more and −5 ° C. or less in a viscoelasticity measurement test. Thereby, the composition for pressure-sensitive adhesives of the present embodiment can exhibit good adhesion even if the object to be adhered has a distorted shape, and has an adhesive strength comparable to that at room temperature even under low temperature conditions. It will be obtained.
Moreover, (A) the copolymer which has a vinyl aromatic monomer unit has one or more tan-delta peaks 2 in the range of 0 degreeC or more and 50 degrees C or less in a viscoelasticity measurement test. Thereby, the composition for pressure-sensitive adhesives of the present embodiment has an appropriate adhesive strength, and can exhibit the characteristics that the adhesive strength is maintained even if the adhesive composition is adhered for a long time.
In addition, it is preferable to have one or more tan δ peaks 1 in the range of −65 ° C. or more and −15 ° C. or less, and one or more tan δ peaks 2 in the range of 5 ° C. or more and 45 ° C. or less. It is more preferable to have one or more tan δ peaks 1 in the range of 25 ° C and one or more tan δ peaks 2 in the range of 10 ° C to 40 ° C.

The copolymer (A) preferably has a tan δ (loss tangent) at 25 ° C. of 0.10 or more.
Thereby, the softness | flexibility of the composition for adhesives becomes favorable, and even if the to-be-adhered body is a distorted surface, it can be made to contact | adhere reliably.
The tan δ value at 25 ° C. is more preferably 0.15 or more, and further preferably 0.25 or more.

The tan δ (loss tangent) value and the tan δ peak can be measured by cutting a measurement sample into a predetermined size and using a predetermined viscoelasticity measuring device.
For example, a sample for measurement is cut into a size of 10 mm in width and 35 mm in length, set in a twist type geometry of an apparatus ARES (trade name, manufactured by TI Instruments Inc.), and the effective measurement length is 25 mm, strain 0.5%, frequency 1 Hz, a value obtained from −70 ° C. to 50 ° C. at a heating rate of 3 ° C./min. The tan δ peak temperature is determined from a peak detected by automatic measurement of RSI Orchestrator (trade name, manufactured by TI Instrument Co., Ltd.).
In the present embodiment, the tan δ value at the peak temperature is preferably 0.1 or more.

As a method for controlling the tan δ peak and the tan δ value, “a method in which a copolymer block of a hydrogenated conjugated diene and / or alkylene and a vinyl aromatic compound is contained in the copolymer (A)”, “copolymer” Vinyl content and distribution derived from conjugated diene before hydrogenation contained in (A), and hydrogenation amount of conjugated diene contained in copolymer (A), or alkylene contained in copolymer (A) α-olefin content and distribution of 3 or more carbon atoms from the molecular weight distribution, and a method "to control the content of block mainly composed of vinyl aromatic compounds.

The copolymer (A) preferably contains the following (a) and two or more types of (b) blocks.
(A) Polymer block mainly composed of vinyl aromatic monomer unit (b) Copolymer block mainly composed of alkylene unit and vinyl aromatic monomer unit or conjugated diene unit and vinyl aromatic monomer unit Hydrogenated copolymer block mainly composed of

The copolymer (A) preferably contains at least one of the following blocks (a) to (c).
(A) Polymer block mainly composed of vinyl aromatic monomer unit (b) Copolymer block mainly composed of alkylene unit and vinyl aromatic monomer unit or conjugated diene unit and vinyl aromatic monomer unit (C) A polymer block mainly composed of alkylene units or a hydrogenated polymer block mainly composed of conjugated diene units. As a result, the adhesive strength of the pressure-sensitive adhesive composition over time Change can be reduced, and the production efficiency of the copolymer (A) can be improved.

In the present embodiment, the names of the monomer units constituting the copolymer are in accordance with the names of the monomers from which the monomer units are derived.
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 embodiment, “mainly” means that the copolymer contains 60 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. It is more preferable that 1,3-butadiene and isoprene are mainly composed of 1,3-butadiene from the viewpoint of obtaining high mechanical strength in the pressure-sensitive adhesive composition of 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.

The “alkylene unit” refers to a monoolefin unit such as an ethylene unit, a propylene unit, a butylene unit, a hexylene unit, and an octylene unit. In particular, an ethylene unit, a propylene unit and a butylene unit are preferred from the viewpoint of economy.
Alkylene refers to monoolefins such as ethylene, propylene, butene, hexene and octene.
These may be used alone or in combination of two or more.

The method for polymerizing the copolymer (A) is not particularly limited, and examples thereof include coordination polymerization, anionic polymerization, and cationic polymerization. Anionic polymerization is preferred from the viewpoint of easy control of the structure.
As a method for producing an anionic polymerization block copolymer, a known method can be applied. 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.

Examples of the structure of the copolymer (A) include at least one structure selected from the following general formula group.
_{c- (b-a) n,} c- (a-b) n, c- (a-b-a) n, c- (b-a-b) n, a-c- (b-a) n , A-c- (ab) _n , a-c- (b-a) _n -b [(abc) _n ] _m -X, [(a- (b-c) _n ] _m -X, [(ab) _n -c] _m -X, [(ab-a) _n -c] _m -X, [(b-ab) _n -c] _m -X, [ (C-b-a) _n ] _m- X, [c- (b-a) _n ] _m- X, [c- (ab-a) _n ] _m- X, or [c- (b- a−b) _n ] _m −X
a is a polymer block mainly composed of vinyl aromatic monomer units.
b is a copolymer block mainly comprising an alkylene unit and a vinyl aromatic monomer unit or a hydrogenated copolymer block mainly comprising a conjugated diene unit and a vinyl aromatic monomer unit.
c is a polymer block mainly composed of alkylene units or a hydrogenated polymer block mainly composed of conjugated diene units.
When a plurality of polymer blocks are present in the copolymer (A), the structures such as molecular weight and composition may be the same or different. In addition, the boundary and the end of each block need not be clearly distinguished.

The distribution of vinyl aromatic monomer units in each of the polymer blocks a and b is not limited as long as the content of the vinyl aromatic compound is within the range described above, and may be tapered, stepped, convex, evenly distributed. Or may be distributed in a concave shape.
In addition, a crystal part may be present in the polymer block.
In each copolymer block, a plurality of segments having different vinyl aromatic compound contents may coexist.
X is, for example, silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, polyhalogenated hydrocarbon compound, carboxylic acid ester compound, polyvinyl compound, bisphenol type epoxy compound, alkoxysilane compound, halogenated silane compound, ester series A residue of a coupling agent such as a compound or a residue of an initiator such as a polyfunctional organolithium compound is shown.

In said general formula, m and n show an integer greater than or equal to 1, and it is preferable that it is an integer of 1-5.
The distribution of the vinyl unit of the conjugated diene unit in each block is not particularly limited, but may be a distribution.
The distribution of vinyl units can be controlled by a method such as adding a vinylating agent during polymerization or changing the temperature during polymerization.
Further, there may be a distribution in the hydrogenation rate of the conjugated diene unit. The distribution of the hydrogenation rate is changed by changing the distribution of vinyl units, or after copolymerizing isoprene and butadiene, and then hydrogenating using the catalyst described below, and the difference in the hydrogenation rate between the isoprene units and the butadiene units is determined. It can be controlled by the method used.

  The copolymer (A) has a block structure (a) a polymer block mainly composed of vinyl aromatic monomer units, and (b2) a hydrogenated copolymer mainly composed of conjugated diene units and vinyl aromatic monomer units. The copolymer preferably contains a polymer block and (c2) a hydrogenated polymer block mainly composed of a conjugated diene unit.

From the viewpoint of obtaining good heat resistance in the pressure-sensitive adhesive composition of the present embodiment, the copolymer (A) is a polymer block mainly composed of a vinyl aromatic monomer unit in the above general formula group. It is preferable to have a structure containing two or more, more preferably a copolymer block mainly composed of a vinyl aromatic monomer unit at both ends of the copolymer (A). Specifically, the structure of ac- (ba) _n in the above general formula can be given.
Thus, cohesive force improves by making it the structure which has a polymer block which mainly has a vinyl aromatic monomer unit in the both terminal part of a copolymer (A), and the adhesive in this embodiment The adhesive strength of the composition for use can be increased.

  The content of the polymer block mainly composed of the above-mentioned (a) vinyl aromatic monomer unit contained in the copolymer (A) is excellent in heat resistance and practical use in the pressure-sensitive adhesive composition of the present embodiment. From the viewpoint of obtaining sufficient tensile strength, it is preferably 10% by mass or more, and from the viewpoint of obtaining good flexibility and ensuring adhesion, it is preferably 50% by mass or less. (A) The content of the polymer block mainly composed of vinyl aromatic monomer units is preferably in the range of 13 to 45% by mass, and more preferably in the range of 15 to 40% by mass. Thereby, the composition for adhesives excellent in the balance of adhesiveness, adhesive strength, and adhesive force is obtained.

The copolymer block (B) contained in the copolymer (A) is a copolymer block mainly composed of an alkylene unit and a vinyl aromatic monomer unit, or water mainly composed of a conjugated diene unit and a vinyl aromatic monomer unit. The content of the additive copolymer block is preferably 25% by mass or more from the viewpoint that the change over time in the adhesive strength after the lapse of a predetermined time immediately after bonding in the pressure-sensitive adhesive composition in the present embodiment is small. 80 mass% or less is preferable from a viewpoint of obtaining sufficient adhesiveness to a body. The content of the above in the co-polymer (A) (b) is more preferably in the range of 30 to 70 wt%, more preferably in the range of 35 to 60 wt%.

The copolymer block (B) contained in the copolymer (A) is a copolymer block mainly composed of an alkylene unit and a vinyl aromatic monomer unit, or water mainly composed of a conjugated diene unit and a vinyl aromatic monomer unit. The content of the vinyl aromatic monomer unit contained in the copolymer block is that the adhesive strength in the present embodiment has little change with time in the adhesive strength after a predetermined time from immediately after pasting in the pressure-sensitive adhesive composition. From the viewpoint, 10 to 90 mass% is preferable, 30 to 85 mass% is more preferable, 45 to 80 mass% is more preferable, and 55 to 75 mass% is still more preferable.
In particular, the content of the vinyl aromatic monomer unit contained in the hydrogenated copolymer block mainly comprising (b2) conjugated diene unit and vinyl aromatic monomer unit, which is limited to the above (b), In the composition for pressure-sensitive adhesives in the present embodiment, 10 to 90% by mass is preferable, 30 to 85% by mass is more preferable, and 45 to 90% by mass is more preferable, from the viewpoint that there is little change with time in the adhesive strength immediately after pasting. More preferably, it is -80 mass%, and it is still more preferable that it is 55-75 mass%.

The content of the vinyl aromatic monomer unit in the copolymer (A) is obtained by obtaining good heat resistance in the productivity of the copolymer (A) described later and the pressure-sensitive adhesive composition of this embodiment. From the viewpoint that there is little change in the adhesive strength with time even after a lapse of a predetermined time immediately after combining, 35% by mass or more is preferable. Moreover, 80 mass% or less is preferable from a viewpoint of obtaining the favorable adhesiveness to a to-be-adhered body, It is more preferable that it is the range of 40-75 mass%, It is further more preferable that it is the range of 50-70 mass%.
When the content of the vinyl aromatic monomer unit in the copolymer (A) is less than 35% by weight, the polymer finish is inferior, and the polymer solution after polymerization is desolvated with water vapor and then dehydrated. The polymer becomes large lumps and does not take up finishing equipment. Further, since the polymer becomes sticky when the temperature is raised even in the drying step of the polymer, it takes a long time at a low temperature to dry, resulting in poor productivity.

The vinyl bond amount in the conjugated diene unit contained before hydrogenation in the copolymer (A) is preferably 5 mol% or more from the viewpoint of obtaining good adhesion in the pressure-sensitive adhesive composition of the present embodiment. 75 mol% or less is preferable from the viewpoint of reducing the change with time in the adhesive strength after a predetermined time immediately after the combination, more preferably in the range of 10-60 mol%, and still more preferably in the range of 10-50 mol%.
The “vinyl bond amount” refers to 1,2-bonds and 1,2-bonds, 1,2-bonds, and 1,4-bonds that are incorporated in the conjugated diene before hydrogenation. It is the ratio of those incorporated by 3,4-bonds.
The above “vinyl bond amount” can be calculated by the Hampton method using a copolymer (A) before hydrogenation and using an infrared spectrophotometer (device name: FT / IR-230; manufactured by JASCO Corporation). .

  In the copolymer (A), the amount of vinyl bonds in the conjugated diene unit contained before hydrogenation of the hydrogenated copolymer block mainly composed of the (b2) conjugated diene unit and the vinyl aromatic monomer unit is as follows: From the viewpoint of obtaining good adhesiveness in the productivity of the copolymer (A) and the composition for pressure-sensitive adhesives of this embodiment, 5 mol% or more is preferable, and the productivity of the copolymer (A), this embodiment In the composition for pressure-sensitive adhesives, 60 mol% or less is preferable, a range of 10 to 40 mol% is more preferable, and a range of 15 to 30 mol% is more preferable from the viewpoint that there is little change in the adhesive strength with time after a predetermined time has passed since the pasting. Further preferred.

  From the viewpoint that the hydrogenation rate of all conjugated diene units in the copolymer (A) is less changed with time in the adhesive strength after the lapse of a predetermined time immediately after bonding in the pressure-sensitive adhesive composition of the present embodiment, and From the viewpoint of improving heat aging resistance, 60 mol% or more is preferable, 75 mol% or more is more preferable, 90 mol% or more is more preferable, and 95 mol% or more is even more preferable.

Examples of the hydrogenation method include 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, (3 ) 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.

The copolymer (A) 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.

In the copolymer (A), the content of (c) the polymer block mainly composed of alkylene units or the hydrogenated polymer block mainly composed of conjugated diene units is applied in the pressure-sensitive adhesive composition of the present embodiment. It is preferably 10% by mass or more from the viewpoint of obtaining good adhesion to the body, and is preferably 70% by mass or less from the viewpoint that there is little change with time in the adhesive strength immediately after the predetermined time has passed since the pasting. The range is more preferably 15 to 60% by mass, and still more preferably 15 to 50% by mass.
In particular, in the copolymer (A), the content of the hydrogenated polymer block mainly composed of (c2) conjugated diene units, which limited the above (c), is applied in the pressure-sensitive adhesive composition of this embodiment. It is preferably 10% by mass or more from the viewpoint of obtaining good adhesion to the body, and is preferably 70% by mass or less from the viewpoint that there is little change with time in the adhesive strength immediately after the predetermined time has passed since the pasting. The range is more preferably 15 to 60% by mass, and still more preferably 15 to 50% by mass.

  The amount of vinyl bonds in the conjugated diene unit contained before hydrogenation of the hydrogenated polymer block mainly comprising (c2) conjugated diene unit in the copolymer (A) is the composition for pressure-sensitive adhesives of this embodiment. From the viewpoint of obtaining good adhesion to an adherend in an article, it is preferably 20 mol% or more, and from the viewpoint of little change with time in the adhesive strength after a predetermined time immediately after bonding, 85 mol% or less is preferable. The range of 30-75 mol% is more preferable, and the range of 40-65 mol% is more preferable.

The weight average molecular weight and number average molecular weight of the copolymer (A) are preferably 50,000 or more from the viewpoint of realizing practically sufficient adhesiveness in the pressure-sensitive adhesive composition of this embodiment, and good moldability is obtained. From the viewpoint, it is preferably 400,000 or less, more preferably from 50,000 to 300,000, and even more preferably from 100,000 to 250,000.
In the case of sequential polymerization, the copolymer (A) preferably has a smaller molecular weight distribution (= weight average molecular weight / number average molecular weight), preferably 1.2 or less.
Specifying the molecular weight distribution narrowly in this way is effective from the viewpoint of obtaining a practically sufficient adhesive strength, maintaining the adhesive strength for a long time after bonding, and maintaining a stable adhesive force for a long time. .
The weight average molecular weight can be determined by gel permeation chromatography (GPC).

Copolymer (A) is another thermoplastic synthetic resin in the composition for pressure-sensitive adhesives of this embodiment in order to improve the adhesion to the adherend and to increase the adhesive strength, adhesive strength, etc. You may use together.
Thermoplastic resins include polyethylene, polypropylene, butadiene resin, acrylonitrile / styrene resin, acrylonitrile / butadiene / styrene resin, polymethacrylstyrene, methacrylic resin, styrene, olefin, polyester, polyurethane, etc. Examples include plastic elastomers and petroleum resins as various tackifiers. In particular, hydrogenated styrene elastomers, ethylene vinyl acetate copolymers, acrylic copolymers, and tackifying resins are suitable.

((B) Hydrogenated styrene elastomer)
In the composition for adhesives of this embodiment, you may further contain (B) hydrogenated styrene-type elastomer.
(B) Although it does not specifically limit as hydrogenated styrene-type elastomer, For example, styrene-ethylene-butylene-styrene (SEBS) which saturated styrene-butadiene-styrene (SBS), styrene-isoprene-styrene by hydrogenation, Styrene-ethylene-propylene-styrene (SEPS) is a typical hydrogenated styrene-based 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-based 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, halogen A reactive elastomer having a functional group, which includes a silicon halide group, an alkoxysilicon group, a tin halide group, a boronic acid group, a boron-containing group, a boronate group, an alkoxytin group, and a phenyltin group, may be used.

((C) ethylene vinyl acetate copolymer)
In the composition for adhesives of this embodiment, you may further contain (C) ethylene vinyl acetate copolymer.
(C) Although ethylene vinyl acetate copolymer is not specifically limited, For example, ethylene and vinyl acetate can be manufactured by radical copolymerization under high temperature and high pressure conditions. The properties differ depending on the vinyl acetate content, but are not particularly limited.

((D) Acrylic copolymer)
In the composition for adhesives of this embodiment, you may further contain (D) acrylic type copolymer.
(D) Although an acrylic copolymer is not specifically limited, For example, the copolymer of methyl acrylate, ethyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, vinyl chloride, styrene etc. is mentioned.

Regarding the composition ratio of the above “copolymer (A)”, “(B) hydrogenated styrene elastomer”, “(C) ethylene vinyl acetate copolymer”, “(D) acrylic copolymer”, Although there is no limitation, a component (A) is 10 mass%-80 mass%, a component (B) is 20 mass%-90 mass%, Preferably, a component (A) is 20 mass%-70 mass%, a component (B ) Is 30% by mass to 80% by mass, more preferably 30% by mass to 60% by mass of component (A), and 40% by mass to 70% by mass of component (B).
When the blending ratio of the component (A) is less than 20% by mass, the adhesiveness in the pressure-sensitive adhesive composition of the present embodiment is lowered, and the adhesive strength is changed after being adhered for a long time immediately after bonding. In addition, the adhesive strength under low temperature conditions is further reduced.
When the blending ratio of the component (A) exceeds 80% by mass, the adhesive strength and the adhesive strength are lowered in the pressure-sensitive adhesive composition of the present embodiment, which is not preferable.

((E) tackifier resin)
In the composition for adhesives of this embodiment, you may further contain (E) tackifier resin.
As the tackifier resin, there is no particular limitation, for example, rosin terpene resin, hydrogenated rosin terpene resin, coumarone resin, phenol resin, terpene-phenol resin, aromatic hydrocarbon resin, Known tackifying resins such as aliphatic hydrocarbon resins can be used. 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.
(E) By using a tackifier resin, the adhesion strength is improved.
Content of (E) tackifier resin in the composition for adhesives of this embodiment is 0-200 mass parts when a copolymer (A) is 100 mass parts, Preferably it is 0-100 mass parts. Used in the range of
If the amount used exceeds 200 parts by mass, the adhesive strength after long-term sticking becomes too strong, and an adhesive residue tends to be generated at the time of peeling, which is not preferable.

((F) softener)
In the composition for adhesives of this embodiment, you may further contain (F) softener.
(F) As the softener, either a mineral oil softener or a synthetic resin softener can be used.
Mineral oil softeners generally include mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Paraffinic hydrocarbons account for 50% or more of all carbon atoms. Is called paraffinic oil, naphthenic hydrocarbons with 30-45% carbon atoms are called naphthenic oils, and aromatic hydrocarbons with 35% or more carbon atoms are aromatic. It is called oil.
(F) As the softening agent, paraffinic oil which is a softening agent for rubber is preferable, and as the synthetic resin softening agent, for example, polybutene, low molecular weight polybutadiene and the like are preferable.

(F) By containing a softening agent, in the composition for adhesives of this embodiment, adhesiveness and adhesiveness are improved.
The content of the softening agent (F) in the pressure-sensitive adhesive composition of the present embodiment secures a practically sufficient mechanical strength in the pressure-sensitive adhesive composition of the present embodiment and suppression of bleeding of the softening agent (F). From the viewpoint, it is preferably 0 to 100% by mass.
(F) As for content in the composition for adhesives of a softener, the range of 0-50 mass% is more preferable, and the range of 0-30 mass% or less is further more preferable.

(Antioxidants, light stabilizers, etc.)
You may add stabilizers, such as antioxidant and a light stabilizer, to the composition for adhesives 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.

  The pressure-sensitive adhesive composition of the present embodiment includes other pigments such as bengara and titanium dioxide; waxes such as paraffin wax, microcrystalline wax, and low molecular weight polyethylene wax; amorphous polyolefin, ethylene-ethyl Polyolefin or low molecular weight vinyl aromatic thermoplastic resins such as acrylate copolymers; natural rubber; polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene rubber A synthetic rubber such as polypentenamer rubber may be added. Examples of the synthetic rubber include those described in “Rubber / Plastic Compounding Chemicals” (edited by Rubber Digest Co., Ltd.).

[Method for producing composition for pressure-sensitive adhesive]
The composition for adhesives of this embodiment can be manufactured by a conventionally well-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 pressure-sensitive adhesive composition of this embodiment may be foamed in order to achieve lightening, softening, and adhesion improving effects. Examples of the foaming method include a chemical method, a physical method, and use of a thermal and 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 has a configuration including a pressure-sensitive adhesive layer obtained by laminating and forming the above-described pressure-sensitive adhesive composition of the present embodiment on a predetermined base film.
As 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, and the polar resin is polyethylene terephthalate, polybutylene. Preferred examples include polyester resins such as terephthalate, polyamide resins, ethylene-vinyl acetate copolymers and hydrolysates thereof.
1 μm or more and 100 μm or less is preferable, and 5 to 100 μm is more preferable for the layer of the pressure-sensitive adhesive composition constituting the surface protective film of this embodiment.
When the thickness of the layer of the composition for pressure-sensitive adhesives 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 base film is 5 mm or less, preferably 3 mm or less, 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.

As a manufacturing method of the surface protection film in this embodiment, the method by a film extruder and the method of coating are mentioned, for example.
First, as a method using a film extruder, the component of the pressure-sensitive adhesive composition layer and the thermoplastic resin component of the base film layer are made into two flows in a melt co-extruder, that is, an adhesive layer is formed. It can be manufactured by combining the adhesive fluid and the resin film layer by joining the fluid for forming and the fluid for forming the substrate body film in the die mouth to form a single fluid and extruding it.
As a method for coating, it can be produced by dissolving the pressure-sensitive adhesive layer composition in a predetermined solvent, preparing a coating solution, and applying this to a base film.
In the case of a method using a film extruder, the pressure-sensitive adhesive composition is excellent in productivity because it can be produced by dry blending each component of the pressure-sensitive adhesive composition in advance.
Moreover, as a coating method, it can manufacture by melt | dissolving the composition for adhesives in the solvent which can be melt | dissolved, apply | coating on a base film using a coater etc., and heat-drying a solvent. Suitable solvents for the pressure-sensitive adhesive composition include cyclohexane, toluene, xylene, diethyl ether, tetrahydrofuran, chloroform and the like.

Examples of the present invention and comparative examples will be specifically described below.
First, evaluation methods and physical property measurement methods applied to Examples and Comparative Examples are shown below.

I. Evaluation of composition and structure of copolymer (A) containing vinyl aromatic monomer unit (I-1) Styrene content, vinyl bond content of conjugated diene, hydrogenation rate of double bond based on conjugated diene In polymer The styrene content, the vinyl bond content of the conjugated diene, and the hydrogenation rate of the double bond based on the conjugated diene were measured by nuclear magnetic resonance spectrum analysis (NMR) under the following conditions.
Measuring instrument: JNM-LA400 (manufactured by JEOL)
Solvent: Deuterated chloroform Sample: Sample taken before and 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) Content of polymer block mainly composed of vinyl aromatic monomer M.M. Kolthoff, et al. , J. et al. Polym. Sci. , 1946, Vol. 1, p. It was measured by the osmium tetroxide method described in 429.
Measurement sample: sample taken before polymer is hydrogenated Polymer decomposition solution: solution of 0.1 g of osmic acid dissolved in 125 mL of tertiary butanol

(I-3) Weight average molecular weight and molecular weight distribution The weight average molecular weight and molecular weight distribution of the vinyl aromatic monomer unit-containing copolymer (A) were measured by gel permeation chromatography (GPC) under the following conditions. did.
The molecular weight distribution was calculated from the ratio of the obtained weight average molecular weight and number average molecular weight.
Measuring device: LC-10 (manufactured by Shimadzu Corporation)
Column: TSKgel GMHXL (4.6 mm ID × 30 cm), 2 solvents: Tetrahydrofuran Calibration curve sample: commercially available standard polystyrene (manufactured by Tosoh Corporation), 10-point measurement

(I-4) tan δ peak and tan δ value at 25 ° C. The measurement material was cut into a size of 10 mm in width and 35 mm in length to obtain a measurement sample.
A measurement sample is set in the twisted geometry of the device ARES (manufactured by TI Instrument Co., Ltd., trade name), the effective measurement length is 25 mm, the strain is 0.5%, the frequency is 1 Hz, and -70 ° C. The measurement was performed up to 50 ° C. under conditions of a temperature rising rate of 3 ° C./min.
The tan δ peak temperature is a value obtained from a peak detected by automatic measurement of RSI Orchestrator (trade name, manufactured by TI Instrument Co., Ltd.).

II. Characteristics (II-1) Adhesiveness of Adhesive Composition Surface protective film prepared in Examples 1 to 8 and Comparative Examples 1 to 8 below on a PMMA plate (arithmetic surface roughness: 1.1 μm) Pasted and rolled at 23 ° C x 50% relative humidity using a 1kg weight rubber roll (diameter: 10cm) at a constant speed, and then visually observed the area ratio between the contacted part and the gap part. did.
The adhesion was evaluated according to the following four levels.
A: No bubble that can be visually observed with respect to the peeled area (1 m ² ).
A: One bubble can be visually observed with respect to the peeled area (1 m ² ).
×: ² to 4 bubbles that can be visually observed with respect to the peeled area (1 m ² ).
XX: 5 or more bubbles that can be visually observed with respect to the peeled area (1 m ² ).

(II-2) 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.
Using a surface protective film produced in the following Examples 1 to 8 and Comparative Examples 1 to 8 having a loop shape of 180 mm length × 20 mm width, as an adherend, a PMMA plate (surface arithmetic average roughness: 0.1 μm) The contact area is 15 mm × 50 mm, the contact interval (distance between the lower end of the upper chuck and the upper surface of the PMMA plate) is 30 mm, the adhesion time is 10 sec, the adhesion and peeling speed is 500 mm / min, and the adhesive force ( g / 10 mm).
In addition, the measurement temperature was made into 2 types, 0 degreeC and 23 degreeC.

(II-3) Adhesive strength (g / 25mm)
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 8 and Comparative Examples 1 to 8 below was attached to a PMMA plate (surface arithmetic average roughness: 0.1 μm), and the 180 ° peeling test was performed at a temperature of 23 ° C. Two types were performed immediately after pasting and for a long time.
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.
The evaluation of long-time adhesion was measured after pasting the surface protective film prepared in Examples 1 to 8 and Comparative Examples 1 to 8 below on a PMMA plate and leaving it at 23 ° C. and 50% relative humidity for 28 days. did.

III. Preparation of hydrogenation catalyst The hydrogenation catalyst used for the hydrogenation reaction of the copolymer (A) containing a vinyl aromatic monomer unit 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 copolymer (A) containing vinyl aromatic monomer unit <Polymer 1: Hydrogenated product of styrene-butadiene-styrene / butadiene-styrene (acba)>
Here, a to c represent the following polymer blocks, respectively.
a: Polystyrene block b: Copolymer of butadiene and styrene block c: Polybutadiene single block A stirrer and a jacketed tank reactor having an internal volume of 10 L are washed, dried and purged with nitrogen, and batched by the following method. Polymerization was performed.
First, a cyclohexane solution (concentration 20% by mass) containing 15 parts by mass of styrene was added.
Next, 0.06 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. 0.7 mol was added with respect to 1 mol of lithium, and it polymerized at 70 degreeC for 30 minutes.
Thereafter, a cyclohexane solution (concentration: 20% by mass) containing 20 parts by mass of butadiene was added and polymerized at 70 ° C. for 30 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 15 parts by mass of butadiene and 35 parts by mass of styrene was added and polymerized at 70 ° C. for 1 hour.
Finally, a cyclohexane solution containing 15 parts by mass of styrene (concentration 20% by mass) was added and polymerization was performed at 70 ° C. for 30 minutes.
The polymer obtained as described above has a styrene content of 65% by mass, a polystyrene block (a) content of 30% by mass, a polybutadiene single block (c) part with a vinyl bond content of 48 mol%, and the co-polymerization of butadiene and styrene. The vinyl bond content of the combined block (b) part was 21 mol%, the weight average molecular weight of the whole polymer was 177,000, and the molecular weight distribution was 1.10.
Next, 100 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 hydrogenated block copolymer (Polymer 1) had a butadiene hydrogenation rate of 99%.

<Polymer 2: Hydrogenated product of styrene-butadiene-styrene / butadiene-styrene (acba)>
Here, a to c represent the following polymer blocks, respectively.
a: polystyrene block b: copolymer block of butadiene and styrene c: single block of polybutadiene In the same manner as in the synthesis of polymer 1 above, a stirring device and a jacketed tank reactor having an internal volume of 10 L are washed, dried, and nitrogen Substitution was carried out and batch polymerization was carried out by the following method.
After the cyclohexane solution containing 10 parts by mass of styrene is charged into the reactor, 0.05 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers, and 0.7% of TMEDA with respect to 1 mol of n-butyllithium. Mole was added and polymerized at 70 ° C. for 30 minutes.
Thereafter, a cyclohexane solution containing 25 parts by mass of butadiene was added and polymerized at 70 ° C. for 30 minutes.
Next, a cyclohexane solution containing 15 parts by mass of butadiene and 40 parts by mass of styrene was added and polymerized at 70 ° C. for 1 hour.
Finally, a cyclohexane solution containing 10 parts by mass of styrene was added and polymerized at 70 ° C. for 30 minutes.
The polymer obtained as described above has a styrene content of 60% by mass, a polystyrene block (a) content of 20% by mass, a polybutadiene single block (c) part having a vinyl bond content of 43 mol%, and the co-polymerization of butadiene and styrene. The vinyl bond content in the combined block (b) part was 18 mol%, the weight average molecular weight of the whole polymer was 222,000, and the molecular weight distribution was 1.11.
Next, 100 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 hydrogenated block copolymer (Polymer 2) had a butadiene hydrogenation rate of 99%.

<Polymer 3: Hydrogenated product of styrene / butadiene / styrene (ba)>
Two tank reactors with an internal volume of 10 L and a stirrer and a jacket were used, followed by washing, drying, and nitrogen substitution to carry out continuous polymerization.
From the bottom of the first reactor, a cyclohexane solution containing butadiene (concentration 20 mass%) was fed at a feed rate of 3.3 kg / hr, and a cyclohexane solution containing styrene (concentration 20 mass%) was 4.8 kg / hr. At a feed rate, the cyclohexane solution containing n-butyllithium is supplied at a feed rate of 0.077 parts by mass with respect to 100 parts by mass of all monomers, and the cyclohexane solution containing TMEDA is added to 1 mol of n-butyllithium. Each of them was fed at a feed rate of 0.44 mol, and continuous polymerization was carried out at 90 ° C.
The average residence time in the first polymerization reactor was about 45 minutes, the butadiene conversion was about 100%, and the styrene conversion was 99%.
The polymer solution from the first unit is supplied from the bottom of the second reactor, and at the same time, a cyclohexane solution containing styrene (concentration 20% by mass) is supplied at a supply rate of 1.9 kg / hr. Was continuously fed at 90 ° C. The conversion of styrene at the outlet of the second reactor was 98%.
The polymer obtained by continuous polymerization had a styrene content of 67% by mass, a polystyrene block (a) content of 20% by mass, a butadiene-styrene copolymer block (b) part vinyl bond content of 16 mol%, The weight average molecular weight was 200,000 and the molecular weight distribution was 1.9.
Next, 100 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 hydrogenated block copolymer (Polymer 3) had a butadiene hydrogenation rate of 99%.

<Polymer 4: Hydrogenated product of styrene-butadiene-styrene (ac-a)>
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 containing 15 parts by mass of styrene is charged into the reactor, and then 0.05 parts by mass of n-butyllithium with respect to 100 parts by mass of all monomers and 0.55 mol of TMEDA with respect to 1 mol of n-butyllithium. Mole was added and polymerized at 70 ° C. for 30 minutes.
Thereafter, a cyclohexane solution containing 70 parts by mass of butadiene was added and polymerized at 70 ° C. for 1 hour.
Finally, a cyclohexane solution containing 15 parts by mass of styrene was added and polymerized at 70 ° C. for 30 minutes.
The polymer obtained as described above has a styrene content of 30% by mass, a polystyrene block (a) content of 30% by mass, a polybutadiene single block (c) part having a vinyl bond content of 38 mol%, and a total molecular weight of 32. The weight average molecular weight of the polystyrene block was 32,000, and the molecular weight distribution was 1.03.
Next, 100 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 hydrogenated block copolymer (Polymer 4) had a butadiene hydrogenation rate of 99%.

<Polymer 5: Hydrogenated product of styrene-butadiene-styrene / butadiene-styrene (acba)>
Hydrogenation reaction was performed by adding 58 ppm of a hydrogenation catalyst as titanium per 100 parts by mass of the polymer.
Other conditions were the same as (Polymer 1) described above to obtain a hydrogenated block copolymer (Polymer 5).
The hydrogenation rate of butadiene in the hydrogenated block copolymer (Polymer 5) was 70%.

  Table 1 below shows the composition, structure, and molecular weight of the obtained copolymer components (A): (Polymers 1 to 4) and (Polymer 5).

[Example 1]
A 15% toluene solution of the above (Polymer 1) was prepared as the block copolymer (A).
Next, using an applicator, the above toluene solution was applied to a 25 μm thick polyester film, air-dried in a draft for 30 minutes, and then the toluene was completely evaporated in an oven at 70 ° C. to provide a pressure-sensitive adhesive layer. A protective film was prepared.
The pressure-sensitive adhesive layer had a thickness of 15 μm.
The surface protective film was measured for adhesion, adhesive strength (immediately after bonding, 23 ° C. × 14 days later), and adhesive strength (23 ° C., 0 ° C.). The measurement results are shown in Table 2 below.

[Example 2]
Using (Polymer 2) instead of (Polymer 1), a 15% toluene solution was prepared, and using this, a surface protective film was prepared in the same manner as in Example 1, and each characteristic was measured. The measurement results are shown in Table 2 below.

[Comparative Example 1]
Using (Polymer 3) instead of (Polymer 1), a 15% toluene solution was prepared, and using this, a surface protective film was prepared in the same manner as in Example 1, and each characteristic was measured. . The measurement results are shown in Table 2 below.

[Comparative Example 2]
Using (Polymer 4) instead of (Polymer 1), a 15% toluene solution was prepared, and using this, a surface protective film was prepared in the same manner as in Example 1, and each characteristic was measured. .
The measurement results are shown in Table 2 below.

[Reference Example 1]
Using (Polymer 5) instead of (Polymer 1), a 15% toluene solution was prepared, and using this, a surface protective film was prepared in the same manner as in Example 1, and each characteristic was measured. .
The measurement results are shown in Table 2 below.

Example 3
(Polymer 1) is used as the block copolymer (A). This polymer 1 is 50% by mass, a hydrogenated elastomer (polymer structure is EB-S-EB-S, styrene content is 13%, butadiene before hydrogenation. A vinyl content of 73% and a melt flow rate · MFR (230 ° C., 2.16 kg load) of 3.5 g / 10 min) were mixed at a ratio of 50% by mass to prepare a 15% toluene solution of this mixture.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 3 below.

Example 4
(Polymer 2) is used in place of (Polymer 1), the ratio of (Polymer 2) and the hydrogenated elastomer is adjusted to the values shown in Table 3 below, and other conditions are the same as in Example 3. % Toluene solution was prepared.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 3 below.

[Comparative Example 3]
(Polymer 3) is used in place of (Polymer 1), the ratio of (Polymer 3) and the hydrogenated elastomer is adjusted to the values shown in Table 3 below, and other conditions are the same as in Example 3. % Toluene solution was prepared.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 3 below.

[Comparative Example 4]
(Polymer 4) is used instead of (Polymer 1), the ratio of (Polymer 4) and the hydrogenated elastomer is adjusted to the values shown in Table 3 below, and other conditions are the same as in Example 3. % Toluene solution was prepared.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 3 below.

[Reference Example 2]
(Polymer 5) is used in place of (Polymer 1), the ratio of (Polymer 5) and the hydrogenated elastomer is adjusted to the values shown in Table 3 below, and other conditions are the same as in Example 3. % Toluene solution was prepared.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 3 below.

[Example 5], [Example 6], [Reference Example 3], [Reference Example 4]
The ratio of (Polymer 1) and hydrogenated styrene-based elastomer was adjusted to the values shown in Table 4 below, and a 15% toluene solution was prepared in the same manner as in Example 3 under other conditions.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 4 below.

Example 7
(Polymer 1), hydrogenated styrene elastomer, ethylene vinyl acetate copolymer (Evaflex EV45X (VA content: 46 mass%), manufactured by Mitsui DuPont Polychemical Co., Ltd.) and acrylic copolymer (acrylic copolymer) A polymer-containing solvent-type pressure-sensitive adhesive, ARONTAC S-1601 (solid content 30%), manufactured by Toa Gosei Co., Ltd.) has the composition shown in Table 4 below, and the other conditions are the same as in Example 3 with 15% toluene. A solution was made.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 4 below.

Example 8
(Polymer 1), hydrogenated styrene elastomer, tackifier resin (hydrogenated petroleum resin, Alcon P115, manufactured by Arakawa Chemical Industries, Ltd.) and softener (Diana Process Oil PW90, manufactured by Idemitsu Kosan Co., Ltd.) are shown in the table below. A 15% toluene solution was prepared in the same manner as in Example 3 except for the composition shown in FIG.
Using the 15% toluene solution, a surface protective film was produced in the same manner as in Example 1, and each characteristic was measured.
The measurement results are shown in Table 4 below.

As shown in Table 2, in Examples 1 and 2, the pressure-sensitive adhesive composition has excellent flexibility, good adhesion, and the adhesive strength is maintained for a long time. Sufficient adhesive strength was obtained under both low temperature conditions and normal temperature conditions.
On the other hand, in Comparative Example 1, since the copolymer (A) does not have a tan δ (loss tangent) peak in the range of −70 ° C. or more and −5 ° C. or less, the adhesion, adhesion strength, and adhesive strength are In any case, good practical evaluation was not obtained.
Further, in Comparative Example 2, the copolymer (A) does not have a tan δ (loss tangent) peak in the range of 0 ° C. or more and 50 ° C. or less. It was not obtained.

  In Reference Example 1, since the copolymer (A) has a low hydrogenation rate of all conjugated dienes, the pressure-sensitive adhesive composition is slightly inferior in adhesion, and the adhesive strength is bonded. Compared to immediately after that, the temperature after 23 ° C. × 14 days was higher, and the adhesive strength was somewhat unstable.

As shown in Table 3, in each of Examples 3 and 4, good adhesion and practically sufficient evaluation of adhesive strength were obtained, and the adhesive strength after storage for a long time immediately after bonding was obtained. There was no change and good characteristics were shown.
On the other hand, in Comparative Example 3, the copolymer 3 (A) of the polymer 3 contained in the pressure-sensitive adhesive composition has a tan δ (loss tangent) peak in the range of −70 ° C. or more and −5 ° C. or less. Therefore, practically good evaluation was not obtained in any of adhesion, adhesive strength, and adhesive strength.
In Comparative Example 4, since the copolymer (A) of the polymer 4 contained in the pressure-sensitive adhesive composition does not have a tan δ (loss tangent) peak in the range of 0 ° C. or higher and 50 ° C. or lower, There was a significant difference in the adhesive strength after storage for a long time immediately after bonding, and it was difficult to peel easily.

  In Reference Example 2, since the copolymer (A) has a low hydrogenation rate of all conjugated dienes, the pressure-sensitive adhesive composition has an adhesive strength of 23 ° C. × 14 days after bonding. However, the adhesive strength was unstable.

  As shown in Table 4, in each of Examples 5 to 8, good adhesion and practically sufficient evaluation of adhesive strength were obtained, and the adhesive strength after storage for a long time immediately after bonding was obtained. There was no change and stable and good characteristics were exhibited.

In Reference Example 3, since the copolymer (A) was too little compared to the hydrogenated styrene elastomer, the adhesion was inferior, and the adhesive strength after 23 ° C. × 14 days was higher than immediately after bonding.
In Reference Example 4, since the copolymer (A) was too much compared to the hydrogenated styrene elastomer, both the adhesive strength and the adhesive strength were low.

  The composition for an adhesive of the present invention is an adhesive for bonding metal, glass, synthetic resin, etc., as an adhesive for surface protection that improves surface scratch resistance and prevents adhesion of dust. There is industrial applicability.

Claims (10)

A pressure-sensitive adhesive composition containing a copolymer (A) having a vinyl aromatic monomer unit,
The copolymer (A) has at least one tan δ (loss tangent) peak 1 in the range of −70 ° C. or more and −5 ° C. or less,
One or more tan δ (loss tangent) peaks 2 in the range of 0 ° C. or more and 50 ° C. or less ,
The composition for adhesives in which the said copolymer (A) contains 1 or more of each block of following (a)-(c) .
(A) Polymer block containing 95% by mass or more of vinyl aromatic monomer unit
(B) a copolymer block containing an alkylene unit and a vinyl aromatic monomer unit or a hydrogenated copolymer block containing a conjugated diene unit and a vinyl aromatic monomer unit, Copolymer block or hydrogenated copolymer block having a content of monomer units of 55 to 90% by mass
(C) A polymer block containing 60% by mass or more of alkylene units or a hydrogenated polymer block containing 60% by mass or more of conjugated diene units The pressure-sensitive adhesive composition according to claim 1, wherein the copolymer (A) has a tan δ (loss tangent) at 25 ° C. of 0.10 or more. The composition for adhesives of Claim 1 or 2 in which the said copolymer (A) contains each block of following (a), (b2), (c2).
(A) Polymer block containing 95% by mass or more of vinyl aromatic monomer unit: 10 to 50% by mass
(B2) A hydrogenated copolymer block containing a conjugated diene unit and a vinyl aromatic monomer unit, wherein the content of the vinyl aromatic monomer unit is 55 to 90% by mass. Combined block : 25-80% by mass
(C2) Hydrogenated polymer block containing 60% by mass or more of conjugated diene units: 10 to 70% by mass The composition for adhesives of Claim 3 whose said copolymer (A) is a polymer by which 60 mol% or more of all the conjugated diene units in the said copolymer (A) was hydrogenated. The composition for adhesives as described in any one of Claims 1 thru | or 4 which has a polymer block which contains 95 mass% or more of vinyl aromatic monomer units in the both terminal part of the said copolymer (A). object. The composition for adhesives as described in any one of Claims 1 thru | or 5 which further contains a 1 or more types of thermoplastic resin. (B) hydrogenated styrene elastomer,
(C) an ethylene vinyl acetate copolymer,
(D) The composition for adhesives as described in any one of Claims 1 thru | or 6 which further contains one or more chosen from the group which consists of an acryl-type copolymer. Copolymer (A): 10% by mass to 80% by mass,
The composition for pressure-sensitive adhesives according to claim 7 , comprising (B) hydrogenated styrene-based elastomer: 20% by mass to 90% by mass. The pressure-sensitive adhesive composition according to any one of claims 1 to 8 , wherein the copolymer (A) has a functional group. The surface protection film in which the layer of the composition for adhesives as described in any one of Claims 1 thru | or 9 of thickness 1 micrometer-100 micrometers is provided on the base film.