JPH11286526A - Thermoplastic block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject copolymer excellent in heat resistance and moldability and processability as well as physical properties such as strength by high hydrogenating an aromatic ring, or the like of a specific compound. SOLUTION: The thermoplastic block copolymer is represented by the formulae (A-B)n -A, (A-B)n+1 , (A-B)n+1 $-X and (A-B)n+1 }N-X [A is a polymer block consisting mainly of a hydrogenated vinyl aromatic hydrocarbon compound (a); B is a polymer block consisting mainly of a hydrogenated conjugated diene compound (b); X is a polyfunctional coupling agent residue; (n) and (m) are each >=1] and, in the copolymer, number-average molecular weight of a polymer of the component (a) before hydrogenation in the polymer block A exceeds 14,000 and hydrogenation ratio obtained by NMR measurement is at least >=80% based on the wholly aromatic ring and at least >=90% based on the wholly olefinic unsaturated double bond and number-average molecular weight-reducing ratio after hydrogenating reaction is <10% and a weight ratio of the components a/b is (10/90) to (90/10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermoplastic block copolymer. More specifically, hydrogenating the unsaturated olefin portion and the aromatic ring of the specific block copolymer,
A thermoplastic hydrogenated block copolymer having a small molecular weight distribution with little decrease in the number average molecular weight during the hydrogenation reaction, and having extremely excellent strength, heat resistance, and moldability. It relates to a copolymer.

[0002]

2. Description of the Related Art Block copolymers composed of a vinyl aromatic hydrocarbon compound and a conjugated diene compound have been widely used in the fields of elastic materials, resin modification, adhesives, transparent resins, and the like. In recent years, hydrogenated block copolymers having improved heat resistance by hydrogenating the double bond of a conjugated diene portion to form a saturated type have also been widely used in resin modifiers, molding materials and the like. Particularly, a block copolymer comprising a styrene compound as a vinyl aromatic hydrocarbon compound, butadiene as a conjugated diene compound and an isoprene compound, and a block copolymer obtained by hydrogenating the diene portion thereof have the heat resistance as an elastomer. The resin is excellent in transparency, impact resistance and weather resistance, strength and flexibility, and is used for various materials.

Further, a block copolymer composition obtained by blending a thermoplastic resin or the like with these styrene-based block copolymers and hydrogenated polymers thereof further improves various physical properties such as heat resistance, fluidity and adhesive properties. This is widely practiced. However, in recent years, the market requirements for polymer materials have become increasingly sophisticated, and it is strongly desired to improve the heat resistance and improve the moldability. Conventional styrene-conjugated diene block copolymers are difficult to meet such demands at all, and the same applies to block copolymers in which the diene portion has been hydrogenated. When the molecular weight was increased in order to improve the physical properties, the flowability was extremely low, and the molding processability was greatly reduced.

[0004] In order to greatly improve the heat resistance, a method of increasing the Tg by hydrogenating the aromatic ring of styrene has also been considered, and some studies have already been made. For example, U.S. Pat. No. 3,333,024 describes an example in which a styrene aromatic ring and an unsaturated olefin moiety of a styrene-isoprene-styrene block copolymer having a relatively low molecular weight are hydrogenated. There is no example of a copolymer, and in the hydrogenation method described, molecular chain scission occurs during the reaction, so that the obtained block copolymer has reduced physical properties.

Further, US Pat. Nos. 5,352,744 and WO 96/34896 disclose a method of hydrogenating a styrene aromatic ring and an unsaturated olefin moiety of a styrene-isoprene-styrene block copolymer having a relatively low molecular weight. And the improvement in Tg of the styrene block portion was confirmed. However, in these patent specifications,
In particular, there is no description of a high molecular weight elastomer, the molecular weight of the styrene block before hydrogenation is low, and the effect of improving heat resistance is not at the level of the present invention.

Further, Japanese Patent Application Laid-Open No. Hei 3-160051 discloses that an styrene aromatic ring and an unsaturated olefin portion of a styrene-butadiene block copolymer having a high styrene content are hydrogenated to improve heat resistance and to improve the optical material. However, in the hydrogenation method described, the molecular chain was severely cut during the reaction, and the number-average molecular weight reduction rate after the reaction greatly exceeded 10%. Improvement of physical properties such as strength of the block copolymer is small. In any case, at present, block copolymers having both higher heat resistance and moldability have not been obtained, and high-molecular-weight elastomers with particularly excellent elasticity have not been obtained at all. It is a fact.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a thermoplastic block copolymer which is excellent in heat resistance, molding workability and physical properties such as strength.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and as a result, have found that the aromatic copolymer of a vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer having a specific structure has A block copolymer in which the ring and unsaturated olefin moieties are highly hydrogenated, and which has no molecular chain breakage during the hydrogenation reaction, has improved heat resistance and has extremely high fluidity and excellent molding processability, and is extremely excellent. It was found that the strength was high. More surprisingly, the present inventors have found that even a high molecular weight block copolymer having a vinyl aromatic hydrocarbon compound content of 50% or less and a number average molecular weight of more than 200,000 shows sufficient moldability, and completed the present invention.

That is, the present invention relates to the general formulas (AB) _n -A, (AB) _{n + 1} , (AB) _{n + 1-}
X, {(AB) _{n + 1} } _m- X (where A is a polymer block mainly composed of a hydrogenated vinyl aromatic hydrocarbon compound, and B is mainly composed of a hydrogenated conjugated diene compound) X is a polyfunctional coupling agent residue, and n and m are integers of 1 or more.), And a vinyl aromatic hydrocarbon compound in the polymer block A before hydrogenation. Number average molecular weight of the polymer is 1
The hydrogenation rate obtained by NMR measurement is at least 80% or more of all aromatic rings, at least 90% or more of all olefinically unsaturated double bonds, and the number average after hydrogenation reaction is more than 4,000. 10% reduction in molecular weight
Is a block copolymer having a weight ratio of a vinyl aromatic hydrocarbon compound to a conjugated diene compound in the copolymer before hydrogenation of from 10/90 to 90/10. It is.

Hereinafter, the present invention will be described in detail. The present invention
Thermoplastic block copolymer in which the aromatic ring and unsaturated olefin moiety of the vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer having a specific structure are hydrogenated and the molecular chain is substantially not broken during the hydrogenation reaction. It is united.
In the present invention, the number average molecular weight of the vinyl aromatic hydrocarbon compound polymer before hydrogenation in the block copolymer is 14,00.
When the molecular weight is more than 0 and is less than 0, the degree of improvement in heat resistance of the block copolymer is low. Further, the present invention relates to a block copolymer having a number average molecular weight reduction rate of less than 10% after the hydrogenation reaction, and a block copolymer having a number average molecular weight reduction rate of more than 10% has severely broken molecular chains, , Elasticity and the like are low.

Hereinafter, the present invention will be described in more detail. The block copolymer of the present invention comprises a polymer block A mainly composed of a hydrogenated vinyl aromatic hydrocarbon compound and a polymer block B mainly composed of a hydrogenated conjugated diene compound.
It is composed of Examples of the vinyl aromatic hydrocarbon compound include styrene, α-methylstyrene,
One or more kinds are selected from alkylstyrenes such as p-methylstyrene and p-tert-butylstyrene, paramethoxystyrene, vinylnaphthalene and the like, and styrene is particularly preferred.

In the present invention, the polymer mainly composed of a vinyl aromatic hydrocarbon compound refers to a case in which one or more vinyl aromatic hydrocarbon compounds are used, or a polymer which is subjected to living anion polymerization with these compounds. The case where the compound of (1) is copolymerized is also included. Examples of these copolymerizable compounds include conjugated diene compounds, methyl methacrylate, methacrylates such as butyl methacrylate,
Cyclohexadiene, caprolactone and the like can be mentioned.
The form of copolymerization may be any form such as random, alternating, or tapered, and when there are a plurality of polymer blocks A, the composition, molecular weight and the like of each may be different.

[0013] The term "mainly composed of a vinyl aromatic hydrocarbon compound" in the present specification means that the hydrogenated vinyl aromatic hydrocarbon compound is at least 50 mol% or more, preferably 70 mol% or more, in the polymer block A. More than mol%. Further, as the conjugated diene compound, for example, one or more kinds are selected from butadiene, isoprene, 1,3-cyclohexadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like. Among them, butadiene, isoprene and a combination thereof are preferred. The microstructure of the conjugated diene compound before hydrogenation can be arbitrarily selected. For example, in the case of a polybutadiene block, the amount of 1,2 bonds in the side chain is 10 mol% or more and 90 mol% or more.
It is preferable that it is less than 20 mol%, and especially for elastic material use, it is preferably 20 mol% or more and less than 60 mol%.

In the present invention, the polymer mainly composed of a conjugated diene compound also includes a case where another compound capable of living anionic polymerization with the conjugated diene compound is copolymerized. These other copolymerizable compounds include:
Vinyl aromatic hydrocarbon compound, methyl methacrylate,
Examples include methacrylates such as butyl methacrylate, cyclohexadiene, caprolactone, and the like. The form of copolymerization may be any form such as random, alternating, or tapered, and when there are a plurality of polymer blocks B, the composition, molecular weight, etc. of each may be different.

Further, in the present specification, the meaning of mainly comprising a conjugated diene compound means that the hydrogenated conjugated diene compound accounts for at least 50 mol% or more, preferably 70 mol% or more in the polymer block B. It is. In the present invention, the number average molecular weight of the vinyl aromatic hydrocarbon compound polymer before hydrogenation contained in the polymer block A is more than 14,000. If it is 14,000 or less, the Tg after hydrogenation of the aromatic ring is low, and the effect of improving heat resistance such as strength at a high temperature is low, so that it does not satisfy market requirements. Although there is no particular upper limit for the molecular weight,
If it exceeds 000, the effect of improving heat resistance is sufficient, but problems may occur in molding workability and the like.

The block copolymer of the present invention preferably has a number average molecular weight in terms of polystyrene of 35,000 or more. Although there is no particular upper limit for the molecular weight, it is preferably 600,000 or less, and more preferably 50,000 or more.
Desirably, it is not more than 00,000. 35,000
When it is below, strength and elasticity are small, and 600,0
When it exceeds 00, the effect of improving heat resistance is sufficient, but problems may occur in molding workability and the like.

The structure of the block copolymer in the present invention may be in any form such as linear, branched, radial, comb-shaped or a mixture thereof. Preferred structures include ABA, ABAB,
(AB) _4- X and the like. In addition, A
A block copolymer having a -B structure may be contained. Further, a tapered block copolymer in which the boundary between each block becomes a random copolymer and its composition gradually changes is also included.

The weight ratio of the vinyl aromatic hydrocarbon compound to the conjugated diene compound contained in the block copolymer of the present invention before hydrogenation is arbitrarily selected between 10/90 and 90/10. 10% vinyl aromatic hydrocarbon compound content
If it is less than 90%, the effect of improving heat resistance cannot be obtained, and if it exceeds 90%, impact resistance becomes low, which is not preferable. In particular, for elastic materials, the weight ratio is 10/90 to
When the ratio is 50/50, the balance between heat resistance, strength, moldability and elasticity is excellent, but more preferably, 20/80 to 40/60 is excellent as an elastic material.

The block copolymer of the present invention is obtained by hydrogenating at least 80%, preferably at least 90%, of all aromatic rings, and at least 90%, preferably at least 95%, of all olefinically unsaturated double bonds. The above is the result of hydrogenation. Hydrogenation rate of all olefinically unsaturated double bonds is 90
%, Deterioration by heat, light, etc. is severe, leading to a decrease in thermoplasticity and physical properties. On the other hand, when the hydrogenation rate of the wholly aromatic ring is less than 80%, Tg is low, heat resistance and strength are poor, and moldability is poor. The hydrogenation rate can be measured by NMR.

The block copolymer of the present invention must have a number-average molecular weight reduction rate of less than 10% after the hydrogenation reaction. Preferably less than 5%, more preferably 3%
%. When the number-average molecular weight reduction rate after the hydrogenation reaction is 10% or more, the molecular chains are severely cut during the hydrogenation reaction, and the physical properties, particularly the strength and the elastic properties such as permanent elongation, are significantly reduced. Thus, the effect of the present invention can no longer be obtained. The number-average molecular weight reduction after the hydrogenation reaction can be measured by gel permeation chromatography (GPC).

Examples of the method for producing the block copolymer before hydrogenation include the methods described in JP-B-36-19286, JP-B-43-14979, and JP-B-49-36957. These use an organolithium compound or the like as an anionic polymerization initiator in a hydrocarbon solvent, add an ether compound such as diethyl ether or tetrahydrofuran, or a tertiary amine such as triethylamine or tetramethylethylenediamine to the side of the conjugated diene compound block. Controls the amount of chain binding and the binding mode,
In addition, if necessary, a polyfunctional compound such as epoxidized soybean oil or silicon tetrachloride is used as a coupling agent, and a vinyl aromatic hydrocarbon compound and a conjugated diene compound are block-copolymerized. A block copolymer before hydrogenation having a branched or radial structure is obtained.

As a method for hydrogenating the block copolymer, a method is used in which the olefinic double bond of the conjugated diene compound and the aromatic ring of the vinyl aromatic hydrocarbon compound in the block copolymer are hydrogenated in one step. For example, in a hydrocarbon solvent, a metal catalyst such as Pd or Rh supported on an alumina carrier is added in an amount of 1% to 100% by weight based on the weight of the block copolymer.
And the reaction temperature is from 120 ° C. to 250 ° C., preferably 1 ° C.
30 ° C. to 220 ° C., hydrogen partial pressure 2 MPa to 25 MPa,
Preferably, a method of reacting at 3 MPa to 20 MPa is used. After completion of the reaction, it is preferable to separate the catalyst by a known method and to recycle the catalyst. In addition, a two-stage hydrogenation method in which the olefinic double bond of the conjugated diene compound in the block copolymer is first hydrogenated by a known method, and then the aromatic ring of the vinyl aromatic hydrocarbon compound is hydrogenated by the above method. The addition method may be used. However, considering the simplicity of the process, the productivity and the like, the one-step reaction is more preferable.

The block copolymer of the present invention may contain, if necessary, an inorganic filler, a stabilizer, a lubricant, a coloring agent, silicone oil,
Mineral oil, flame retardants and the like can be added. Examples of the inorganic filler include calcium carbonate, magnesium carbonate, talc, magnesium hydroxide, mica, barium sulfate, white carbon, titanium oxide, and carbon black. Examples of the stabilizer include a hindered phenol-based antioxidant, a phosphorus-based heat stabilizer, a hindered amine-based light stabilizer, and a benzotriazole-based UV absorber. Examples of the lubricant include stearic acid, stearic acid ester, stearic acid amide, metal stearate and the like. As the mineral oil, a paraffin component, a naphthene component, and an aroma component can be used in an arbitrary ratio. When mixing the above components with the block copolymer of the present invention, any kneading apparatus such as a Banbury mixer, a Labo Plastomill, a single screw extruder, and a twin screw extruder may be used.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

[Example] (Method of analysis of block copolymer and evaluation of physical properties) Determination of styrene content of block copolymer: Using a UV spectrophotometer, the absorbance of a chloroform solution of the block copolymer was measured, and the styrene content was determined. The styrene content in the block copolymer was determined from a calibration curve in which the relationship between absorbances was measured in advance.

Molecular weight of block copolymer and styrene block chain length before hydrogenation: Calculated by gel permeation chromatography (GPC) using commercially available standard polystyrene for preparing a GPC calibration curve. The styrene block chain length before hydrogenation was measured by a GPC method on a styrene block obtained by subjecting a block copolymer before hydrogenation to osmate decomposition in chloroform. Hydrogenation rate of block copolymer: measured from H-NMR spectrum. Melt flow rate (MFR): Measured under the conditions of 2.16 kg load and 230 ° C. according to JIS K7210.

Hardness: Measured according to JIS K6301, A type. Breaking strength and elongation: Based on JIS K6301, a sample was a compression molded sheet having a thickness of 2 mm, and the test piece was a No. 3 dumbbell. Permanent elongation: According to JIS K6301, sample is 2mm
Using a thick compression molded sheet, the test piece was a No. 3 dumbbell, and the residual strain after 100% elongation was measured. Rebound resilience: measured with a Dunlop trypsometer.
The sample used was a compression molded sheet having a thickness of 4 mm.

(Method of polymerizing block copolymer) In a 40-liter autoclave purged with nitrogen, 26 l of purified and purified cyclohexane, 65 g of tetrahydrofuran, styrene 6
After charging 20 g, the temperature was raised to 60 ° C., a cyclohexane solution containing 2.7 g of n-butyllithium was added, polymerization was started, and after the polymerization of styrene was completed, butadiene was added in 1 part.
940 g was added, and after the polymerization was completed, styrene 62 was added.
0 g was added to complete the polymerization reaction, and the number average molecular weight was 10
A triblock copolymer (SBS) having a styrene content of 6,000, a styrene content of 39%, a styrene block chain length of 15,200, and a side chain of a butadiene portion of 32 mol% was obtained (block copolymer A-1).

Hereinafter, the amounts of tetrahydrofuran, n-butyllithium, styrene, and butadiene were changed, and polymerization was carried out in the same manner except for the above. In some cases, styrene, butadiene, styrene, and butadiene were successively polymerized. As a result, various block copolymers (A-1 to A-7) before hydrogenation shown in Table 1 were obtained. In a 40 L autoclave purged with nitrogen, 26 L of cyclohexane and 88 L of tetrahydrofuran were purified and dried.
g, 990 g of styrene, and the temperature was raised to 60 ° C.
A cyclohexane solution containing 3.5 g of n-butyllithium was added, polymerization was started, and after styrene polymerization was completed, 2210 g of butadiene was added. After the polymerization was completed, 2.2 g of silicon tetrachloride was added, and the coupling reaction was performed. Completed, number average molecular weight 320,000, styrene content 31
%, A styrene block chain length of 16,900, a side chain of a butadiene portion of 38 mol%, and a radial triblock copolymer ((SB ₄ ) -Si + S) containing 5% of a diblock copolymer.
B, A-8).

[0029]

[Table 1]

Example 1 In a 2 l autoclave,
After completion of the polymerization, 1200 g of a 13.5% by weight cyclohexane solution of 13.5% by weight of the block copolymer A-1 in which the growth terminal was terminated by adding 1.2 equivalents of methanol to Li was added. After adding 48 g of 5% palladium alumina powder (particle diameter 20 microns) manufactured by the company, the inside of the system was replaced with hydrogen, the temperature was raised to 180 ° C., and the hydrogen pressure was 8.3 MPa.
a, A hydrogenation reaction was performed for 6 hours, and the hydrogenation rate of the unsaturated olefin portion was 100%, and the hydrogenation rate of the aromatic ring was 99.4%.
The number average molecular weight of the polymer after hydrogenation is 104,0
00, the number average molecular weight reduction rate was 1.9 compared to that before hydrogenation.
%, And a hydrogenated block copolymer having a molecular weight distribution of 1.03 was obtained.

Example 2 A hydrogenation reaction was carried out on the block copolymer A-2 using the same method as in Example 1, and the hydrogenation rate of the unsaturated olefin portion was 100%, and the hydrogenation of the aromatic ring was 100%. The ratio was 99.2%, the number average molecular weight of the polymer after hydrogenation was 138,000, and the number average molecular weight reduction rate was 1.4% and the molecular weight distribution was 1.04 compared to that before hydrogenation.
Was obtained.

Example 3 A block copolymer A-3 was subjected to a hydrogenation reaction using the same procedure as in Example 1 except that the amount of the 5% palladium alumina powder was changed to 96 g, to thereby obtain an unsaturated olefin portion. The hydrogenation rate was 99.8%, the hydrogenation rate of the aromatic ring was 99.3%, the number average molecular weight of the polymer after hydrogenation was 217,000, and the number average molecular weight reduction rate was 2.4 compared to that before hydrogenation. %, Molecular weight distribution is 1.05
Was obtained.

Example 4 A block copolymer A-4 was subjected to a hydrogenation reaction in the same manner as in Example 3, and the hydrogenation rate of the unsaturated olefin portion was 99.7%.
The hydrogenation rate of the aromatic ring was 99.2%, the number average molecular weight of the polymer after hydrogenation was 226,000 million, and the number average molecular weight reduction rate was 2.2% and the molecular weight distribution was 1.20 compared to that before hydrogenation.
Thus, a hydrogenated block copolymer No. 05 was obtained.

Example 5 A hydrogenation reaction was carried out on the block copolymer A-8 using the same method as in Example 3, and the hydrogenation rate of the unsaturated olefin portion was 99.7% and the hydrogen content of the aromatic ring was 9 At an addition rate of 99.2%, the number average molecular weight of the polymer after hydrogenation was 315,000, the number average molecular weight reduction rate was 1.6%, and the molecular weight distribution was 1.11 compared to before the hydrogenation.
Was obtained.

(Comparative Example 1) Using the same procedure as in Example 1, block copolymer A-1 was heated at 160 ° C. at 4.degree.
A hydrogenation reaction was performed for 8 hours, and the hydrogenation rate of the unsaturated olefin portion was 99.4%, and the hydrogenation rate of the aromatic ring was 62.6.
% Of partially hydrogenated block copolymer was obtained.

(Comparative Example 2) Using the same procedure as in Example 1, block copolymer A-2 was treated at 160 ° C. with 3.
A hydrogenation reaction was performed for 6 hours, and the hydrogenation rate of the unsaturated olefin portion was 99.3%, and the hydrogenation rate of the aromatic ring was 41.2%.
% Of partially hydrogenated block copolymer was obtained.

(Comparative Example 3) The same procedure as in Example 1 was used except that 5% ruthenium alumina powder (particle size: 20 microns) manufactured by NE Chemcat was used instead of 5% palladium alumina powder. A hydrogenation reaction was performed on the block copolymer A-2, and the hydrogenation rate of the unsaturated olefin portion was 100%, the hydrogenation rate of the aromatic ring was 98.8%, and the number average molecular weight of the polymer after hydrogenation was 121,000. The number average molecular weight reduction rate is 13.6% compared to before hydrogenation,
A hydrogenated block copolymer having a molecular weight distribution of 1.20 was obtained.

Comparative Example 4 Nissan Gardler Co., Ltd. 65% nickel diatomaceous earth 20 instead of 5% palladium alumina powder
A block copolymer A--3 was subjected to a hydrogenation reaction using the same method as in Example 1 except that 0 g was used,
The hydrogenation rate of the unsaturated olefin portion is 100%, the hydrogenation rate of the aromatic ring is 98.6%, the number average molecular weight of the polymer after hydrogenation is 174,000, and the number average molecular weight reduction rate is 21. A 6% hydrogenated block copolymer having a molecular weight distribution of 1.31 was obtained.

Comparative Example 5 A block copolymer A-6 was subjected to a hydrogenation reaction in the same manner as in Example 1. The hydrogenation rate of the unsaturated olefin portion was 100%, and the hydrogenation of the aromatic ring was 100%. The ratio was 99.6%, the number average molecular weight of the polymer after hydrogenation was 100,500, and the number average molecular weight reduction rate was 0.5% and the molecular weight distribution was 1.03 compared to that before hydrogenation.
Was obtained.

Comparative Example 6 A block copolymer A-7 was subjected to a hydrogenation reaction in the same manner as in Example 1. The hydrogenation rate of the unsaturated olefin portion was 100%, and the hydrogenation of the aromatic ring was 100%. The ratio was 99.6%, the number average molecular weight of the polymer after hydrogenation was 114,000, and the number average molecular weight reduction rate was 0.9% and the molecular weight distribution was 1.03 compared with that before hydrogenation.
Was obtained. Table 2 shows the physical property evaluation results of the present invention.

[0041]

[Table 2]

By hydrogenating the aromatic ring by 90% or more, the heat resistance is greatly improved, the high-temperature tensile strength is extremely high, the flowability is extremely improved, and the block coexistence with excellent moldability is extremely high. Merge. As in the comparative example,
Even if the styrene block chain length before hydrogenation is within the range of the present invention, the block copolymer having a low hydrogenation rate of the aromatic ring or the styrene block chain length of 14 even when the aromatic ring is almost completely hydrogenated. With a block copolymer having a molecular weight of 2,000 or less, the heat resistance is low, the tensile strength at high temperatures is extremely low, and deformation and stickiness occur. Further, when the aromatic ring hydrogenation rate is low, the effect of improving the fluidity is poor and the balance of physical properties is poor. On the other hand, the block copolymer in which the number-average molecular weight reduction rate after hydrogenation was large was one in which the molecular chain was severely broken during the hydrogenation reaction,
The physical properties, especially the strength, the permanent elongation, and the rebound resilience are drastically reduced, and the same effects as those of the present invention can no longer be exhibited.

Example 6 A hydrogenation reaction was carried out on the block copolymer A-5 using the same procedure as in Example 1, and the hydrogenation rate of the unsaturated olefin portion was 100% and the hydrogenation of the aromatic ring was 100%. The ratio was 99.7%, the number average molecular weight of the polymer after hydrogenation was 70,600, and the number average molecular weight reduction rate was 0.06% and the molecular weight distribution was 1.03 compared to that before hydrogenation.
Was obtained. This block copolymer was a thermoplastic block copolymer having significantly improved heat resistance and good moldability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Sasaki 3-13-1, Ushidori, Kurashiki-shi, Okayama Prefecture Asahi Kasei Corporation (72) Inventor Kiyoo Kato 1-3-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa No. Asahi Kasei Kogyo Co., Ltd.

Claims (3)

[Claims] 1. The general formula (AB) _n -A, (AB) _{n + 1} , (AB) _{n + 1} −
X, {(AB) _{n + 1} } _m- X (where A is a polymer block mainly composed of a hydrogenated vinyl aromatic hydrocarbon compound, and B is mainly composed of a hydrogenated conjugated diene compound) X is a polyfunctional coupling agent residue, and n and m are integers of 1 or more.), And a vinyl aromatic hydrocarbon compound in the polymer block A before hydrogenation. Number average molecular weight of the polymer is 1
The hydrogenation rate obtained by NMR measurement is at least 80% or more of all aromatic rings, at least 90% or more of all olefinically unsaturated double bonds, and the number after hydrogenation reaction is more than 4,000. Average molecular weight reduction rate is 10
% Of the block copolymer, wherein the weight ratio of the vinyl aromatic hydrocarbon compound to the conjugated diene compound in the copolymer before hydrogenation is 10/90 to 90/10. Coalescing. 2. The weight ratio of the vinyl aromatic hydrocarbon compound to the conjugated diene compound in the copolymer before hydrogenation is 10/9.
The thermoplastic block copolymer according to claim 1, wherein the ratio is 0 to 50/50. 3. The thermoplastic block copolymer according to claim 2, wherein the side chain of the conjugated diene compound in the copolymer before hydrogenation is 20 mol% to 60 mol%.