JPH07138447A - Polymer composition and pressure-sensitive adhesive - Google Patents

Abstract

PURPOSE:To obtain a polymer composition excellent in heat resistance, weather resistance and pressure-sensitive adhesion and useful for a pressure-sensitive adhesive tape, etc., by blending a specified diblock copolymer or a specified triblock copolymer with another specified triblock copolymer. CONSTITUTION:This polymer composition is composed of (A) a triblock copolymer composed of an aromatic vinyl monomer polymer block isobutylene polymer block aromatic vinyl monomer polymer block and (B) both or either one of (i) a diblock copolymer composed of an aromatic vinyl monomer polymer block isobutylene polymer block and (ii) a triblock copolymer composed of an isotylene polymer block aromatic vinyl monomer polymer block isobutylene polymer block, different from (A). In addition, the number-average molecular weight of the component (A) is preferably 20000 to 500000 and that of the component (i) or (ii) is preferably 5000 to 400000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer composition having excellent heat resistance and weather resistance and having good adhesiveness, an adhesive composition comprising the same, and an adhesive product.

[0002]

2. Description of the Related Art From the viewpoints of prevention of environmental pollution, safety, resource saving, etc., hot-melt instead of solvent-based pressure-sensitive adhesive or adhesive in which natural rubber, synthetic rubber or other polymer is dissolved in an organic solvent. Type or aqueous emulsion type adhesives and adhesives have been widely used. As a base polymer for hot-melt type pressure-sensitive adhesives and adhesives, a triblock copolymer composed of a vinyl aromatic monomer polymer block-conjugated diene polymer block-vinyl aromatic monomer polymer block is known ( U.S. Pat. No. 3,676,202, U.S. Pat. No. 3,723,
170, etc.). The pressure-sensitive adhesive produced using this triblock copolymer has excellent adhesiveness at room temperature and low temperature, is highly flexible, and easily fluidizes when heated and can be easily applied to a substrate. It has features.
However, since it has a double bond derived from a conjugated diene in the molecule, it is severely deteriorated by ultraviolet rays and heat and has a drawback that it cannot be used in an environment under high temperature or ultraviolet irradiation.

In order to improve the stability against heat and ultraviolet rays, a pressure-sensitive adhesive composition using a triblock copolymer consisting of a styrene polymer block-isobutylene polymer block-styrene polymer block has been developed. However (Japanese Patent Laid-Open No. 4-145184), there is a problem that the adhesiveness is not sufficient, and the fluidity is insufficient at the time of heating, which makes it difficult to perform coating processing.

[0004]

The object of the present invention is to have good heat resistance and weather resistance, and to prevent bleeding from a substrate,
Moreover, it is to provide a polymer composition which has excellent low-temperature characteristics, adhesive strength, workability, and has a large adhesive strength, and which is useful as an adhesive, an adhesive comprising the same, and an adhesive material product using the same. .

[0005]

DISCLOSURE OF THE INVENTION As a result of repeated investigations by the present inventors, a vinyl compound was obtained from a triblock copolymer composed of two vinyl aromatic monomer polymer blocks and one isobutylene polymer block. When at least one of a diblock copolymer consisting of an aromatic monomer and isobutylene and a triblock copolymer consisting of two isobutylene polymer blocks and one vinyl aromatic monomer polymer block is blended, the above-mentioned object is obtained. The present invention has been completed by finding that a base polymer composition for adhesives that is compatible with

That is, the present invention provides (a) a vinyl aromatic monomer polymer block-isobutylene polymer block-vinyl aromatic monomer polymer block triblock copolymer; and (b) a vinyl aromatic monomer polymer. Diblock copolymer (b ₁ ) composed of block-isobutylene polymer block and triblock copolymer composed of isobutylene polymer block-vinyl aromatic monomer polymer block-isobutylene polymer block
A polymer composition comprising at least one of (b ₂ ). Furthermore, the present invention includes a pressure-sensitive adhesive containing the above-mentioned polymer composition, and a pressure-sensitive adhesive material product obtained by applying the pressure-sensitive adhesive to a sheet, tape, or other substrate.

In the present specification, a triblock copolymer consisting of a vinyl aromatic monomer polymer block as "block A", an isobutylene polymer block as "block B", and a block A-block B-block A will be referred to hereinafter. Is an "ABA triblock copolymer", a diblock copolymer consisting of block A-block B is an "AB diblock copolymer", and a triblock consisting of block B-block A-block B. The block copolymer is referred to as "BAB triblock copolymer".

In the above-mentioned diblock copolymer (b ₁ ) and two types of triblock copolymers (a) and (b ₂ ), the vinyl aromatic monomer constituting the block A is styrene, α- Methylstyrene, β-methylstyrene, p-methylstyrene, t-butylstyrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, indene, acenaphthylene, etc. And the block A is formed of one or more of these vinyl aromatic monomers. Among them, it is most preferable that the block A is formed of styrene.

In the polymer composition of the present invention, an ABA triblock copolymer is used as the component (a). This A-
In the B-A triblock copolymer, a polymer block (block A) made of a vinyl aromatic monomer and a polymer block (block B) made of isobutylene are linearly A-shaped.
It is a triblock copolymer in which -BA is bonded in that order.
The total number average molecular weight of the ABA triblock copolymer is preferably in the range of 20,000 to 500,000, more preferably in the range of 25,000 to 450,000. Moreover, the number average molecular weight of each of the two blocks A is 2,500 to 4 but is not limited thereto.
The number average molecular weight of the block B is preferably in the range of 10,000 to 400,000. In the ABA triblock copolymer, the ratio of the structural unit from the vinyl aromatic monomer to the structural unit from isobutylene is 5/95 to 8 by weight.
It is preferably 0/20 and preferably 10/90 to 75/25
Is more preferable. When the weight ratio of the structural unit from the vinyl aromatic monomer to the structural unit from isobutylene is less than 5/95, the cohesive force of the polymer composition becomes small, and the creep resistance is poor, so that a good pressure-sensitive adhesive is obtained. If the ratio is larger than 80/20, on the other hand, the adhesive strength and the flexibility are deteriorated.

Further, the polymer composition of the present invention has the above-mentioned A-
At least one of an AB diblock copolymer and a BAAB triblock copolymer is contained as the component (b) together with the BA triblock copolymer. The AB diblock copolymer comprises a polymer block (block A) made of a vinyl aromatic monomer and a polymer block (block B) made of isobutylene in a linear form, AB or B.
-A is a diblock copolymer bonded in this order,
In the -B triblock copolymer, a polymer block made of isobutylene (block B) and a polymer block made of vinyl aromatic monomer (block A) are linearly B-A.
It is a triblock copolymer which is bonded in the order of -B.

A-B diblock copolymer or B-A-
The number average molecular weight of the B triblock copolymer is preferably in the range of 5,000 to 400,000, and more preferably in the range of 6,000 to 350,000.

Further, an AB diblock copolymer or B
The ratio of the structural unit from the vinyl aromatic monomer to the structural unit from isobutylene in the -AB triblock copolymer is preferably 5/95 to 80/20 by weight, and 10/90 to 75/25 is More preferable. When the weight ratio of the structural unit from the vinyl aromatic monomer to the structural unit from isobutylene is less than 5/95, the compatibility with the ABA triblock copolymer used as the component (a) is poor. Bleed easily. Meanwhile 80 /
When it is larger than 20, the adhesive strength and flexibility are reduced, and particularly at low temperature, the adhesive strength and flexibility are significantly reduced.

ABA triblock copolymers, AB diblock copolymers and BABs used in the present invention.
The triblock copolymer may have a functional group such as a halogen group such as chlorine, a carboxyl group, a hydroxyl group, an acid anhydride group or the like in the molecular chain or at the terminal of the molecule, if necessary. Further, the ABA triblock copolymer, the AB diblock copolymer and the BAB triblock copolymer are
Other cationically polymerizable monomers may be copolymerized within a range that does not impair the performance of the polymer composition of the present invention, and examples of such other cationic monomers include 1-butene, pentene and hexene. , Butadiene, isoprene, methyl vinyl ether and the like.

ABAA triblock copolymer, AB
The method for producing the diblock copolymer and the BAB triblock copolymer is not particularly limited. For example, a vinyl aromatic monomer and isobutylene can be blocked in an inert solvent using a suitable polymerization initiator system. It can be produced by sequentially polymerizing so as to obtain the bonding order. Examples of the polymerization initiator system in that case include a mixed system of a Lewis acid and an organic compound that produces a cationic polymerization active species by the Lewis acid. The Lewis acid is titanium tetrachloride, tin tetrachloride, boron trichloride, aluminum chloride or the like, and the organic compound is an organic compound having a functional group such as an alkoxy group, an acyloxy group or a halogen group, for example, bis (2-methoxy). -2-propyl) benzene, bis (2-acetoxy-2-propyl) benzene,
Examples thereof include bis (2-chloro-2-propyl) benzene. If necessary, amides such as dimethylacetamide and dimethylformamide, and esters such as ethyl acetate may be used as the third component together with the Lewis acid and the organic compound. Further, as an inert solvent for polymerization, hexane, cyclohexane, methylcyclohexane, methyl chloride, methylene chloride and the like can be used.

For example, in the ABA triblock copolymer, a vinyl aromatic monomer is polymerized by using a Lewis acid and an organic compound having one functional group which produces a cationic polymerization active species as a polymerization initiator system. After forming block A, isobutylene is added to the reaction system to polymerize to form block B, and vinyl aromatic monomer is again added to the reaction system to polymerize to form block A. can do. Alternatively, a Lewis acid and an organic compound having two functional groups that generate cationic polymerization active species are used as a polymerization initiator system to first polymerize isobutylene to form a centrally located block B. Can be produced by adding a vinyl aromatic monomer to the reaction system and performing polymerization to form blocks A at both ends of the block B. The AB diblock copolymer and the BAB triblock copolymer can be produced in the same manner.

In the polymer composition of the present invention, the component (a) (ABA triblock copolymer) and the component (b) (A
-B diblock copolymer and / or BAB triblock copolymer) is usually 95/5 to 2 by weight.
It is preferably 0/80, and 90/10 to 25/75
Is more preferable. When both the component (b), the AB diblock copolymer and the BAB triblock copolymer are used, the total amount of them and the proportion of the ABA triblock copolymer are Be within the above range. When the proportion of the component (b) in the polymer composition is less than 5% by weight, the low temperature properties are not improved, while when it exceeds 80% by weight, the cohesive force at high temperature is lowered and sufficient adhesive performance is obtained. It gets harder.

The polymer composition of the present invention may consist of the above-mentioned components (a) and (b) alone, or may contain other components. In particular, when the polymer composition of the present invention is used as a pressure-sensitive adhesive, it is preferable to add a tackifying resin. By blending the tackifying resin, the three characteristics of tackiness, tackiness, and holding power can be adjusted in a well-balanced manner. Tackifying resins are roughly classified into natural resin type and synthetic resin type, and as the natural resin type, rosin type resins such as rosin, gum rosin, tall oil rosin, hydrogenated rosin and maleated rosin, terpene phenol resin, α-pinene. , A terpene resin mainly composed of β-pinene, limonene, an aromatic hydrocarbon-modified terpene resin, and the like. Further, as the synthetic resin-based tackifying resin, an aliphatic-based, alicyclic-based, aromatic-based petroleum resin, coumarone-indene resin, styrene-based resin, alkylphenol resin, phenol resin such as rosin-modified phenol resin, A xylene resin etc. can be mentioned. When the tackifier resin is blended, one or more of the above tackifier resins can be blended, and hydrogenated rosin and styrene resins are particularly preferably used. The amount of the tackifying resin blended can be appropriately selected according to the type of the tackifying resin, the application of the pressure-sensitive adhesive of the present invention, the type of the adherend, etc. It is preferable to add 30 to 500 parts by weight of the tackifying resin to 100 parts by weight in total.

The polymer composition of the present invention, if necessary, contains the process oil as a plasticizer in an amount of 200 parts by weight or less per 100 parts by weight of the total of the components (a) and (b). Good. Further, other polymers may be contained within a range that does not impair the performance of the polymer composition of the present invention. Examples of such other polymers include styrene-ethylene propylene-styrene block copolymers. , Styrene-ethylene propylene block copolymer, styrene-ethylene butylene-styrene block copolymer, E
PR, EPDM, polybutene, polyisobutylene, etc. can be mentioned. Further, the polymer composition of the present invention,
If necessary, various additives may be contained, and examples of such additives include weather resistance, heat resistance, and antioxidants and ultraviolet absorbers for improving the oxidation resistance, and carbonic acid. Examples thereof include inorganic powder fillers such as calcium and titanium oxide, fibrous fillers such as glass fibers and organic reinforcing fibers.

The method for preparing the polymer composition of the present invention is not particularly limited. For example, the component (a) (ABA triblock copolymer) and the component (b) (AB diblock copolymer). And / or BAB triblock copolymer)
Using a known mixing or kneading device such as a kneader ruder, an extruder, a mixing roll, a Banbury mixer, etc., together with the above-mentioned tackifying resin, other polymers and additives as necessary, usually at 110 to 220 ° C. It can be prepared by mixing in the temperature range of. Alternatively, in the step of synthesizing the copolymer, both an isobutylene and a vinyl aromatic compound can be prepared by using both an organic compound having two functional groups and an organic compound having one functional group together with a Lewis acid as a polymerization initiator system. When the monomers are polymerized sequentially, A-B-A
The polymer composition of the present invention, which is a mixture of a triblock copolymer and an AB diblock copolymer, can be directly produced by polymerization, and if necessary, a tackifier resin or another polymer may be added thereto. Combine and mix additives.

A book comprising the component (a) (ABA triblock copolymer) and the component (b) (AB diblock copolymer and / or BAB triblock copolymer) The polymer composition of the invention is particularly useful as a base composition for a pressure-sensitive adhesive, and the pressure-sensitive adhesive can be obtained by blending it with the above-mentioned tackifying resin and other components. Such adhesives are included. Incidentally, the pressure-sensitive adhesive is also called a pressure-sensitive adhesive, and the present invention includes a pressure-sensitive adhesive composed of the component (a), the component (b) and, if necessary, a tackifying resin and other components.

Since the polymer composition or pressure-sensitive adhesive of the present invention usually melts easily and becomes fluid, it is used as a paper, cellophane, organic polymer having a film shape, a sheet shape, a tape shape or other shapes. Various adhesive materials such as an adhesive film, an adhesive sheet and an adhesive tape can be obtained by applying it to a base material such as a film, a sheet and a cloth. Further, in some cases, the polymer composition or the pressure-sensitive adhesive of the present invention is dissolved in toluene or other solvent to form a solution, and the solution is applied to the above-mentioned base material to produce an adhesive product such as an adhesive tape or an adhesive sheet. May be.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Production of Mixture of ABA Triblock Copolymer and AB Diblock Copolymer (1) 800 ml of methylene chloride as a solvent in a reactor equipped with a stirrer and Methylcyclohexane 1200m
l, titanium tetrachloride (Lewis acid) as a polymerization initiator system 4.
3 g and 0.52 g of a mixture of 1,4-bis (2-methoxy-2-propyl) benzene and 2-methoxy-2-propylbenzene were added, and isobutylene 236 was added at -65 ° C.
After charging 4 g and polymerizing for 4 hours, dimethylacedamide (0.13 g) and styrene (41.4 g) were added to give a further 4
Polymerize for a period of time to give ABA triblock copolymer and A-
A mixture (polymer composition) with the B diblock copolymer was prepared. When the polymer composition in this mixture was investigated by a terminal group quantitative method by ¹³ C-NMR, (ABA triblock copolymer) :( AB diblock copolymer)
The content rate of was 70:30 by weight.

(2) The number average molecular weight of the ABA triblock copolymer in the mixture obtained in (1) above was 130,000 when measured by GPC. The content ratio of styrene in the ABA triblock copolymer was determined by ¹ H-NMR to be 15% by weight. When the AB diblock copolymer in the mixture obtained in (1) above was also examined in the same manner, its number average molecular weight was 65,000 and the styrene content was 15% by weight. . (3) Further, the heat resistance and weather resistance of the mixture (polymer composition) obtained in the above (1) were examined as follows, and the results were as shown in Table 1 below.

Heat resistance test of polymer composition: The polymer composition was allowed to stand in air at 120 ° C. for 12 hours, and the colored state was observed with the naked eye. The quality was evaluated according to the evaluation criteria shown in Table 2 below.

Weather resistance test of polymer composition: The polymer composition was subjected to an outdoor exposure test for 1 month in accordance with JIS A1410, and the colored state at that time was observed with the naked eye and touched with a hand to check its stickiness. The quality of weather resistance was checked and judged according to the evaluation criteria shown in Table 2 below.

<Examples 2 to 7> In the same manner as in Example 1, the number average molecular weight and styrene content shown in Table 1 below were obtained.
A mixture (polymer composition) of an ABA triblock copolymer and an AB diblock copolymer having heat resistance and weather resistance was obtained.

Example 8 (1) 800 ml of methylene chloride and 1200 m of methylcyclohexane as a solvent in a reactor equipped with a stirrer.
l, titanium tetrachloride (Lewis acid) as a polymerization initiator system 4.
3 g and 0.33 g of 1,4-bis (2-methoxy-2-propyl) benzene were added, and isobutylene 16 was added at -65 ° C.
After 6 g was charged and polymerized for 4 hours, 0.13 g of dimethylacedamide and 29 g of styrene were added and polymerized for another 4 hours to produce an ABA triblock copolymer. The number average molecular weight and styrene content of the obtained ABA triblock copolymer were as shown in Table 1 below.

(2) In a reactor equipped with a stirrer, 800 ml of methylene chloride and 1200 ml of methylcyclohexane as a solvent, 0.43 g of titanium tetrachloride (Lewis acid) and (2-methoxy-2-propyl) benzene as a polymerization initiator system. Add 0.225g and isobutylene 4 at -65 ° C
After charging 4 g and polymerizing for 4 hours, 0.065 g of dimethylacedamide and 9.75 g of styrene were added to obtain 4
Polymerization was carried out for an hour, 44 g of isobutylene was charged, and polymerization was carried out for 4 hours to produce a BAB triblock copolymer. The number average molecular weight and styrene content of the obtained BAB triblock copolymer were as shown in Table 1 below.

(3) A-B-A obtained in (1) above
The triblock copolymer and the B-A-B triblock copolymer obtained in (2) were mixed at a weight ratio of 70:30 at 150 ° C.
Was kneaded to obtain a polymer composition of the present invention. The heat resistance and weather resistance of the polymer composition obtained as a result are shown in Table 1.

[0031]

[Table 1]

[0032]

[Table 2]

<< Examples 9 to 16 >> Examples 1 to 8 above
Polymer composition (block copolymer mixture) 1 obtained in 1.
00 parts by weight, tackifying resin ("YS-" manufactured by Yasuhara Yushi Kogyo Co., Ltd.
100 parts by weight of PX1000 ") and 1 part by weight of an antioxidant (" Irganox 1010 "manufactured by Ciba-Geigy) were mixed in a melt mixing tank at 200 ° C for 20 minutes to produce an adhesive. This adhesive was coated on a polyester film having a thickness of 100 μm using a coater at a temperature of 160 ° C. and a thickness of 40 μm.
An adhesive tape was prepared by coating the adhesive tape to a coating thickness of.
The melt viscosity and coatability of the pressure-sensitive adhesive during coating were as shown in Table 3 below. The evaluation of coatability is
Very good ⊚, good ∘, slightly bad Δ, bad x, and extremely bad xx. The adhesive performance (pole tack), holding power, adhesive strength, heat resistance, weather resistance, and bleed of the obtained adhesive tape were measured or evaluated by the following methods, and the results are shown in Table 3.

Comparative Example 1 Only the ABA triblock copolymer prepared in (1) of Example 8 was used alone and the same tackification as used in Examples 9 to 16 was applied. An adhesive was prepared by mixing the resin and antioxidant in similar amounts. Thereafter, adhesive tapes were produced in the same manner as in Examples 9 to 16. The melt viscosity and coatability at the time of producing the pressure-sensitive adhesive tape were examined in the same manner as in Examples 9 to 16, and the obtained pressure-sensitive adhesive tape had adhesive performance (pole tack), holding power, adhesive strength, heat resistance, weather resistance and bleeding. Was measured or evaluated by the following method and was as shown in Table 3.

Comparative Example 2 Instead of using 100 parts by weight of the mixture of the ABAA triblock copolymer and the AB diblock copolymer, a styrene-isoprene-styrene triblock copolymer [number average Molecular weight 158,000;
Styrene / isoprene = 15/85 (weight ratio); hydrogenation rate 0%; 1,4 bond amount 89%] and styrene-isoprene diene block copolymer [number average molecular weight 28,000; styrene / isoprene = 22/78 (Weight ratio); Hydrogenation rate 0%;
1,4 bonding amount 89%] 70:30 (weight ratio) mixture 1
The adhesive tape was prepared in the same manner as in Examples 9 to 16 except that 100 parts by weight was used, and the mixture was mixed with a tackifier resin and an antioxidant to prepare an adhesive tape. The melt viscosity and coatability at the time of producing the pressure-sensitive adhesive tape were measured in Examples 9 to 16
In the same manner as above, the pressure-sensitive adhesive tape obtained was measured or evaluated for adhesion performance (pole tack), holding power, adhesive strength, heat resistance, weather resistance and bleeding as shown in Table 3. there were.

COMPARATIVE EXAMPLE 3 Instead of using 100 parts by weight of a mixture of an ABA triblock copolymer and an AB diblock copolymer, a styrene-isoprene-styrene triblock copolymer [number average Molecular weight 130,000;
Styrene / isoprene = 13/87 (weight ratio); hydrogenation rate 97%; 1,4 bond amount 88%] and styrene-isoprene diene block copolymer [number average molecular weight 24,000; styrene / isoprene = 20/80 (Weight ratio); Hydrogenation rate 95
%; 1,4 bonding amount 89%], and 100 parts by weight of a 70:30 (weight ratio) mixture was used, and otherwise the same as in Examples 9 to 16, mixed with a tackifying resin and an antioxidant, and tacked. The agent was prepared, and thereafter an adhesive tape was prepared in the same manner.
The melt viscosity and coatability at the time of producing the pressure-sensitive adhesive tape were measured in Examples 9 to
In the same manner as in item 16, the adhesive tape obtained was tested for its adhesive performance (pole tack), holding power, adhesive strength, heat resistance,
The weather resistance and bleed were measured or evaluated by the following methods, and the results are shown in Table 3.

Adhesiveness (Pole tack) : JIS Z0
According to 237, the pole tack performance at 10 ° C. and 25 ° C. was examined. Here, the larger the pole tack performance, the better the tackiness. The low temperature tack property can be judged by the pole tack value at 10 ° C.

Holding power : 25 mm × 25 mm of adhesive tape
Apply a load of 1 kg to the pasted part of 25 ℃ or 40 ℃
The holding power was evaluated by allowing the sample to stand in an atmosphere of temperature and measuring the time required until it dropped. The longer the holding time is, the better the holding power (creep performance) is.

Adhesive force : The adhesive tape was attached to a stainless steel or polyethylene sheet having a thickness of 1 mm, and the peeling force required when peeling at 180 ° C. was measured.

Heat resistance : Coloring of the pressure-sensitive adhesive portion when the pressure-sensitive adhesive tape was left standing in air at 180 ° C. for 12 hours was visually observed and touched by hand to check the stickiness thereof for evaluation. The heat resistance was evaluated according to the evaluation criteria shown in Table 2 above.

Weather resistance : Adhesive tape is JIS A1410
According to the above, the outdoor exposure test was carried out for one month, and the coloring of the pressure-sensitive adhesive portion was visually observed and touched by hand to check the stickiness thereof for evaluation. The weather resistance was evaluated according to the evaluation criteria shown in Table 2 above.

Bleed : A high-quality paper was attached to an adhesive tape, and the presence or absence of leaching of the adhesive into the high-quality paper when heated at 70 ° C. for 2 weeks was evaluated. Those that were found were evaluated as x.

[0043]

[Table 3]

From the results shown in Table 3 above, the adhesives of Examples 9 to 16 are excellent in all of coatability, adhesive performance, holding power, adhesive strength, heat resistance, weather resistance and bleeding.
On the contrary, the adhesives of Comparative Examples 1 to 3 are inferior in coatability, heat resistance and / or weather resistance.

[0045]

The polymer composition of the present invention and the pressure-sensitive adhesive obtained therefrom have good heat resistance and weather resistance, and do not cause coloring or excessive stickiness even in a heating atmosphere or an atmosphere exposed to ultraviolet rays for a long period of time. . Moreover, since it is melted by heating to be in a fluid state with good handleability, the coatability on a substrate is extremely good, and an adhesive material product such as an adhesive tape or an adhesive sheet can be smoothly produced. Moreover, when the pressure-sensitive adhesive of the present invention is used, a high-quality pressure-sensitive adhesive material such as a pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet having excellent adhesive performance and bleeding resistance and having a large holding force and adhesive force can be obtained.

Front page continuation (72) Inventor Mizuho Maeda 36 Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Kuraray Co., Ltd.

Claims (5)

[Claims] 1. A triblock copolymer comprising (a) a vinyl aromatic monomer polymer block-isobutylene polymer block-vinyl aromatic monomer polymer block; and (b) a vinyl aromatic monomer polymer block-isobutylene polymer. At least one of a diblock copolymer (b ₁ ) composed of a polymer block and a triblock copolymer (b ₂ ) composed of an isobutylene polymer block-vinyl aromatic monomer polymer block-isobutylene polymer block A polymer composition comprising: 2. A triblock copolymer (a) having a number average molecular weight of 20,000 to 500,000, and a diblock copolymer (b ₁ ) or a triblock copolymer (b ₂ ).
The polymer composition according to claim 1, having a number average molecular weight of 5,000 to 400,000. 3. The blending ratio of the triblock copolymer (a) to the diblock copolymer (b ₁ ) and / or the triblock copolymer (b ₂ ) is 95: 5 to 20: by weight.
The polymer composition of claim 1 or 2, which is 80. 4. A pressure-sensitive adhesive containing the polymer composition according to claim 1. 5. An adhesive material product obtained by applying the adhesive of claim 4 to a substrate.