JP2003073434A - Method for producing block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a block copolymer comprising α-methylstyrene polymer block and a conjugated diene polymer block. SOLUTION: The method is characterized in that α-methylstyrene in a concentration of 5-50 mass% is polymerized at -30 to 30 deg.C in the presence of a polar compound in a concentration of 0.1-10 mass% with an organolithium compound in a nonpolar solvent as an initiator, the resulting polymer block A is polymerized with a conjugated diene of 1-100 mol equivalent based on a living poly α-methylstyllithium to obtain a polymer block B1, further the conjugated diene is polymerized at a temperature higher than 30 deg.C to obtain a polymer block B2 and, if necessary, a polyfunctional coupling agent is reacted to be hydrogenated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a block copolymer, more specifically, a specific structure comprising a polymer block mainly composed of α-methylstyrene units and a polymer block mainly composed of conjugated diene units. The present invention relates to a method for producing a block copolymer containing

[0002]

2. Description of the Related Art A glass transition point (Tg) at both ends of a polymer chain
Has a polymer block (constrained phase) higher than room temperature, while Tg is lower than room temperature (rubber phase)
The block copolymer in which is arranged is widely known as a thermoplastic elastomer. Among the thermoplastic elastomers, styrene-conjugated diene block copolymers and styrene-based thermoplastic elastomers that are hydrogenated products thereof,
It is used in many applications such as molding materials, adhesives, and resin modification, and is attracting attention as one of the extremely useful materials.

With the recent advances in industrial technology, the demand for using thermoplastic elastomers at high temperatures tends to increase in the market, and the development of thermoplastic elastomers excellent in high temperature properties is strongly desired. High-temperature properties are especially required in the application fields of automobile parts, electric / electronic parts, films / sheets, medical materials, etc. Specifically, the required high-temperature properties are heat resistance and tensile properties at high temperatures. Mechanical properties such as strength and tensile elongation, compression set and dynamic hysteresis closer to vulcanized rubber. However, the styrene-based thermoplastic elastomer has a problem that the Tg of the styrene polymer block, which is the constrained phase, is about 100 ° C., and the performance as an elastomer is significantly deteriorated under high temperature conditions exceeding this temperature.

Further, it has been reported that the heat resistance of the styrene-based thermoplastic elastomer is improved by blending the poly α-methylstyrene resin, polyolefin, polyphenylene ether, etc. It hasn't met the demand.

As an alternative to the above method, styrene-
It is known to introduce an α-methylstyrene polymer block having a high Tg in place of the styrene polymer block in the conjugated diene block copolymer to improve its high temperature characteristics. The method for producing an α-methylstyrene-conjugated diene block copolymer by this method includes (1) a method of polymerizing α-methylstyrene after the conjugated diene polymerization (Macromolecules, (19
69), 2 (5), 453-458), and (2) a method of polymerizing a conjugated diene after polymerizing α-methylstyrene (K).
autosch. Gummi, Kunstst. , (19
84), 37 (5), 377-379; Polym. B
all. , (1984), 12, 71-77) and (3) a method of sequentially polymerizing α-methylstyrene, a conjugated diene and α-methylstyrene in a hydrocarbon solvent at a polymerization temperature of 60 ° C. (JP-A-61-281163). There are three known methods.

In the above method (1), isoprene is polymerized using a dianion type initiator, and then α-methylstyrene is successively polymerized in a polar solvent (tetrahydrofuran) under a temperature condition of −78 ° C. -Methylstyrene-isoprene block copolymer is being synthesized. Under the polymerization conditions of this method, the amount of 1,4-bond in the conjugated diene block, which is the rubber phase of the resulting block copolymer, is decreased, and as a result, the Tg of the block is increased and the performance as an elastomer is poor, which is preferable. Is hard to say.

Further, in the above method (2), 1,3-methylstyrene is polymerized without using a solvent and then 1,3-
An α-methylstyrene-1,3-butadiene block copolymer is obtained by polymerizing butadiene and stopping the polymerization with a coupling agent of tetrachlorosilane or dichlorodiphenylsilane. In this method, since the polymerization reaction of α-methylstyrene is carried out in the absence of a solvent, increasing the polymerization conversion rate increases the viscosity of the reaction solution and makes it difficult to stir, and the α-methylstyrene polymer block It is difficult to control the molecular weight. For this reason, it is necessary to add a conjugated diene at the time when the polymerization conversion rate of α-methylstyrene is low and polymerize it, but a large amount of α-methylstyrene remaining during the polymerization of the conjugated diene is a conjugated diene that is a rubber phase. It is not preferable because it is copolymerized therein, and the Tg and elastic modulus of the rubber phase in the obtained block copolymer become high, resulting in poor performance as an elastomer.

Further, in the above method (3), a production method in a hydrocarbon solvent at a polymerization temperature of 60 ° C. is exemplified.
Ceiling temperature of α-methylstyrene (temperature at which the polymerization reaction reaches an equilibrium state and the polymerization reaction substantially stops)
Is 61 ° C., and the half-life of α-methylstyryl anion, which is a polymerization active species at 60 ° C. in a hydrocarbon solvent, is very unstable at several minutes, so that the target block copolymer can be obtained. The current situation is that it has not been done.

[0009]

SUMMARY OF THE INVENTION The object of the present invention, however, is to obtain high-temperature properties of an α-methylstyrene polymer block and a conjugated diene polymer block by polymerizing α-methylstyrene at a high polymerization conversion rate. Another object of the present invention is to provide a method for producing an excellent block copolymer.

[0010]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventors with respect to the above-mentioned object, the above-mentioned problems are mainly caused by α-
The present invention has been completed by finding that a block copolymer having a specific structure composed of a polymer block composed of a methylstyrene unit and a polymer block composed mainly of a conjugated diene unit can be produced by a specific anionic polymerization method.

That is, the present invention uses an organolithium compound in a non-polar solvent as an initiator to obtain 0.1 to 10% by mass.
In the presence of a polar compound at a concentration of -30 ° C to 30 ° C, α-methylstyrene at a concentration of 5 to 50% by mass is polymerized, and then the resulting polymer block A is subjected to living poly α-methyl. After polymerizing a conjugated diene in an amount of 1 to 100 molar equivalents with respect to styryllithium to form a polymer block B1, and further polymerizing the conjugated diene at a temperature above 30 ° C. to form a polymer block B2, it is necessary. The method for producing a block copolymer is characterized in that a polyfunctional coupling agent is reacted with and hydrogenated. Further, the present invention uses an organolithium compound in a nonpolar solvent as an initiator and, in the presence of a polar compound at a concentration of 0.1 to 10% by mass, at a temperature of −30 ° C. to 30 ° C., 5 to 50% by mass. % Of α-methylstyrene is polymerized, and then the obtained polymer block A is polymerized with 1 to 100 molar equivalents of conjugated diene based on living poly α-methylstyryllithium to form a polymer block B1. Then, the conjugated diene is further polymerized at a temperature higher than 30 ° C. to obtain a polymer block B
After forming 2, α is added to the living polymer obtained.
-A method for producing a block copolymer, which comprises polymerizing an anion-polymerizable monomer other than methylstyrene and hydrogenating it if necessary.

In the present invention, the resulting block copolymer has at least one block structure A-B1-B2 consisting of the following block A, block B1 and block B2, and constitutes block B1 and block B2. The present invention relates to the above production method, which is a block copolymer in which at least a part of carbon-carbon unsaturated double bonds derived from a conjugated diene unit is optionally hydrogenated. Block A: a polymer block mainly composed of α-methylstyrene units and having a number average molecular weight of 1,000 to 300,000, block B1: mainly composed of a conjugated diene unit and having a number average molecular weight of 500 to 10,000 and 1,4 thereof.
A polymer block having a bond amount of less than 30%, block B2: a polymer block mainly composed of a conjugated diene unit, having a number average molecular weight of 10,000 to 400,000 and having a 1,4-bond amount of 30% or more. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The following method is adopted as the method for producing the block copolymer of the present invention. (1) Using an organolithium compound in a nonpolar solvent as an initiator, in the presence of a polar compound having a concentration of 0.1 to 10% by mass, at a temperature of -30 ° C to 30 ° C, a concentration of 5 to 50% by mass. Of α-methylstyrene, and then the polymer block A thus obtained is polymerized with 1 to 100 molar equivalents of conjugated diene based on living poly α-methylstyryllithium to form a polymer block B1. A method for producing a block copolymer, which comprises further polymerizing a conjugated diene at a temperature higher than 0 ° C. to form a polymer block B2, and then reacting a polyfunctional coupling agent if necessary and hydrogenating. (2) Using an organolithium compound in a nonpolar solvent as an initiator, in the presence of a polar compound having a concentration of 0.1 to 10% by mass, at a temperature of -30 ° C to 30 ° C, a concentration of 5 to 50% by mass. Of α-methylstyrene, and then the polymer block A thus obtained is polymerized with 1 to 100 molar equivalents of conjugated diene based on living poly α-methylstyryllithium to form a polymer block B1. After further polymerizing the conjugated diene to form the polymer block B2 at a temperature higher than ° C, the living polymer obtained is polymerized with an anion-polymerizable monomer other than α-methylstyrene,
A method for producing a block copolymer, which comprises hydrogenating if necessary.

The above method will be described more specifically below. Examples of the organolithium compound used as a polymerization initiator in the above method include n-butyllithium and s
Examples include monolithium compounds such as ec-butyllithium and tert-butyllithium, and dilithium compounds such as tetraethylenedilithium, and these compounds may be used alone or in combination of two or more.

The solvent used in the polymerization of α-methylstyrene is a non-polar solvent, for example, aliphatic hydrocarbons such as cyclohexane, methylcyclohexane, n-hexane and n-heptane, and aromatic hydrocarbons such as benzene, toluene and xylene. A hydrocarbon etc. can be mentioned. These may be used alone or in combination of two or more.

The polar compound used during the polymerization of α-methylstyrene is a compound having no functional group (hydroxyl group, carbonyl group, etc.) that reacts with anionic species and having a hetero atom such as oxygen atom or nitrogen atom in the molecule. Examples of the compound include diethyl ether, monoglyme, tetramethylethylenediamine, dimethoxyethane, and tetrahydrofuran. These compounds may be used alone or in combination of two or more.

The polar compound has a concentration of 0.
It is important to be in the range of 1 to 10% by mass. It is preferably in the range of 0.5 to 3 mass%. When the concentration of the polar compound in the reaction system is less than 0.1% by mass, it becomes difficult to polymerize α-methylstyrene at a high conversion rate, while when the concentration of the polar compound exceeds 10% by mass,
When polymerizing the conjugated diene thereafter, it becomes difficult to control the 1,4-bond amount of the conjugated diene polymer block portion.

It is important that the concentration of α-methylstyrene is in the range of 5 to 50% by mass in the reaction system. It is preferably in the range of 25 to 40% by mass. When the concentration of α-methylstyrene in the reaction system is less than 5% by mass, it becomes difficult to polymerize α-methylstyrene at a high conversion rate. Also, the concentration of α-methylstyrene is 50
When the content is more than mass%, the reaction solution becomes highly viscous in the latter stage of polymerization of α-methylstyrene, and stirring becomes difficult.

The above-mentioned polymerization conversion rate means the unpolymerized α-
It means the rate of conversion of methylstyrene to a block copolymer by polymerization, and in the present invention, the degree is 70%.
It is preferably at least 80%, more preferably at least 85%.

The temperature conditions during the polymerization of α-methylstyrene are as follows: the ceiling temperature of α-methylstyrene (the temperature at which the polymerization reaction reaches an equilibrium state and substantially no longer progresses), α-
From the viewpoint of the polymerization rate of methyl styrene and the living property,
It is important to be in the range of 30 ° C to 30 ° C. More preferably -20 ° C to 10 ° C, even more preferably -15
~ 0 ° C. When the polymerization temperature is higher than 30 ° C., it becomes difficult to polymerize α-methylstyrene at a high conversion rate, and further, the living polymer produced is deactivated at a high rate, and therefore, the homopolymer is obtained in the obtained block copolymer. α-Methylstyrene is mixed in and the physical properties are impaired. If the polymerization temperature is lower than -30 ° C, the reaction solution becomes highly viscous in the latter stage of the polymerization of α-methylstyrene, and stirring becomes difficult, and the cost required for maintaining the low temperature state is high, which is economical. Will be at a disadvantage.

In the above method, as long as the characteristics of the α-methylstyrene polymer block are not impaired, another aromatic vinyl compound is allowed to coexist during the polymerization of α-methylstyrene, and this is copolymerized with α-methylstyrene. May be.
Examples of other aromatic vinyl compounds include styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, vinylnaphthalene, vinylanthracene and the like can be mentioned. The other aromatic vinyl compounds may be used alone or in combination of two or more.

Living poly .alpha.-methylstyryllithium is produced by the polymerization of .alpha.-methylstyrene using organolithium as an initiator, and then conjugated diene is polymerized with this. Examples of the conjugated diene include 1,3-
Butadiene, isoprene, 2,3-dimethyl-1,3-
Examples thereof include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These compounds may be used alone or in combination of two or more. Among these, preferred examples of the conjugated diene are 1,3-butadiene and isoprene, and these may be used as a mixture.

The conjugated diene is subjected to polymerization by adding it to the reaction system in a divided manner. After a small amount of the conjugated diene is polymerized at a low temperature, the conjugated diene is further polymerized at an elevated temperature. The method for adding the conjugated diene to the reaction system is not particularly limited, and may be added directly to the living poly α-methylstyryllithium solution or may be diluted with a solvent and added. As a method for adding the conjugated diene after diluting it with a solvent, the conjugated diene may be added and then diluted with the solvent, or the conjugated diene and the solvent may be added at the same time, or the conjugated diene may be added after being diluted with the solvent. . 1 to 1 for living poly α-methylstyryllithium
After modifying the living active end by adding an amount equivalent to 00 molar equivalents, preferably 5 to 50 molar equivalents of the conjugated diene, it is diluted with a solvent and subsequently the remaining conjugated diene is charged.
A method of carrying out the polymerization reaction at a temperature exceeding 30 ° C., preferably 40 to 80 ° C. is adopted.

Examples of the solvent that can be used for dilution include aliphatic hydrocarbons such as cyclohexane, methylcyclohexane, n-hexane and n-heptane, aromatic hydrocarbons such as benzene, toluene and xylene. be able to. These solvents may be used alone or in combination of two or more. The block polymer consisting of the α-methylstyrene polymer block and the conjugated diene polymer block has good heat resistance and weather resistance, and therefore the carbon-carbon unsaturated double bond of the block copolymer in the block copolymer is preferable. It is preferable that a part or the whole thereof is hydrogenated.

Living poly α-methylstyryllithium A living polymer of a block copolymer consisting of an α-methylstyrene polymer block and a conjugated diene polymer block obtained by copolymerizing a conjugated diene with, for example, a polyfunctional cup A hexablock or radial tereblock type block copolymer can be produced by reacting a ring agent. In this case, the block copolymer may be a mixture obtained by adjusting the amount of the polyfunctional coupling agent to be used, and the mixture may include a coupling body and a block copolymer not involved in the coupling in any proportion. Good. Examples of the polyfunctional coupling agent include phenyl benzoate, methyl benzoate, ethyl benzoate, ethyl acetate, methyl acetate, methyl pivalate, phenyl pivalate, ethyl pivalate, α, α′-dichloro-o- Xylene, α, α′-dichloro-m-xylene,
Examples include α, α′-dichloro-p-xylene, bis (chloromethyl) ether, dibromomethane, diiodomethane, dimethyl phthalate, dichlorodimethylsilane, dichlorodiphenylsilane, trichloromethylsilane, tetrachlorosilane and divinylbenzene.

Hydrogenation (hydrogenation) of the block copolymer obtained by reacting a living polymer of a block copolymer consisting of an α-methylstyrene polymer block and a conjugated diene polymer block with a polyfunctional coupling agent.
In this case, alcohols, carboxylic acids, if necessary, active hydrogen compounds such as water are added to stop the coupling reaction, and then the presence of a hydrogenation catalyst in an inert organic solvent according to a known method. By hydrogenating below, a hydrogenated block copolymer can be obtained.

When hydrogenating a block polymer consisting of an α-methylstyrene polymer block and a conjugated diene polymer block, after the conjugated diene is polymerized with living poly α-methylstyryllithium, alcohols, The active hydrogen compound such as carboxylic acid and water is added to stop the polymerization reaction, and hydrogenated in the presence of a hydrogenation catalyst in an inert organic solvent according to a known method to give a hydrogenated block copolymer. Can be

The hydrogenation reaction is usually carried out in the presence of a hydrogenation catalyst such as a Ziegler catalyst composed of an alkylaluminum compound and cobalt, nickel or the like at a reaction temperature of 20 to 100 ° C. and a hydrogen pressure of 0.1 to 10 MPa. be able to. It is desirable that the unhydrogenated block copolymer be hydrogenated until 90% or more of the unsaturated double bonds derived from the conjugated diene unit are saturated, which can enhance the weather resistance of the block copolymer. . The hydrogenation rate of the unsaturated double bond derived from the conjugated diene unit in the hydrogenated block copolymer is analyzed by iodine value titration method, infrared spectroscopy spectrum measurement, nuclear magnetic resonance spectrum (1H-NMR spectrum) measurement, etc. It can be calculated using a means.

The block A in the block copolymer obtained by the above production method is mainly composed of α-methylstyrene units. The α-methylstyrene unit in the block A is preferably 50% by mass or more, more preferably 70% by mass or more, in order to improve the mechanical properties of the resulting block copolymer at high temperature. Preferably 9
It is 0 mass% or more.

The block A of the above block copolymer may contain other monomer units as a copolymerization component within a range not impairing the gist of the present invention, and a monomer which constitutes the copolymerization component. The body is not particularly limited as long as it is an anion-polymerizable monomer, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, diphenylethylene and the like. The vinyl aromatic compounds, 1,3-butadiene, isoprene, and conjugated dienes such as 2,3-dimethyl-1,3-butadiene are preferable. Particularly preferably,
Styrene, p-methylstyrene, 1,3-butadiene,
Isoprene. The form in which other monomer components are introduced into the block A by copolymerization is not particularly limited, and may be random or tapered.

The polystyrene equivalent number average molecular weight of block A in the block copolymer is preferably 1
000 to 300000, and more preferably 3000
The range is from -100,000. If the molecular weight is less than 1000, the effect of improving the mechanical properties of the resulting block copolymer at high temperature may not be sufficient, while if the molecular weight exceeds 300,000, the processing of the resulting block copolymer may be performed. The sex may not be sufficient.

Next, block B1 in the block copolymer
As the conjugated diene that constitutes 1,3-butadiene,
Examples thereof include conjugated dienes such as isoprene and 2,3-dimethyl-1,3-butadiene. Among these, 1,3-
Butadiene and isoprene are preferable, and 1,3-butadiene is particularly preferable. The conjugated dienes may be used alone or in combination of two or more.

The block B1 may be copolymerized with an anion-polymerizable monomer component other than the conjugated diene within a range not impairing the gist of the present invention. At this time, the form of copolymerization may be random or tapered.

The polystyrene-reduced number average molecular weight of the block B1 is preferably 500 to 10,000, more preferably 1,000 to 7,000.
When the molecular weight is less than 500, the effect of improving the mechanical properties of the obtained block copolymer at high temperature may not be sufficient, while when the molecular weight exceeds 10,000, the rubber of the obtained block copolymer may be obtained. Characteristics may not be sufficient

Furthermore, the conjugated diene units constituting the block B1 obtained by the method of the present invention usually have a 1,4-bond content of less than 30%. 1,4-bond amount is 30%
If it exceeds, the heat deterioration resistance of the block B1 may become insufficient.

The conjugated diene constituting the block B2 in the block copolymer of the present invention includes conjugated dienes such as 1,3-butadiene, isoprene and 2,3-dimethyl-1,3-butadiene. . Among these, 1,3-butadiene and isoprene are preferable, and 1,3-butadiene is particularly preferable. The conjugated dienes may be used alone or in combination of two or more.

In the block B2, an anion-polymerizable monomer component other than the conjugated diene may be introduced by copolymerization so long as the gist of the present invention is not impaired. The form of copolymerization at that time may be random or tapered.

The polystyrene equivalent number average molecular weight of the block B2 is preferably 10,000 to 400,000.
And more preferably in the range of 15,000 to 200,000. When the molecular weight is less than 10,000, the rubber properties of the obtained block copolymer may not be sufficient, while when the molecular weight exceeds 400000, the processability of the obtained block copolymer is not sufficiently improved. There are cases.

Further, the 1,4-bond content of the conjugated diene unit constituting the block B2 obtained by the method of the present invention is usually 30% or more, preferably 35% to 9%.
It is 5%, more preferably 40% to 80%. 1,4-
When the bonding amount is less than 30%, the glass transition temperature (Tg) of the rubber portion made of the conjugated diene becomes high, and the rubber property of the obtained block copolymer may deteriorate.

The structure of the block copolymer obtained by the method of the present invention is not limited to linear, branched, etc.
A block copolymer having at least one B1-B2 structure, for example, A-B1-B2-B2-B1-A type copolymer, A-B1-B2-B2-B1-A type copolymer, A-B1-B2 type copolymer mixture, (A-B1-B
2) nX type copolymer (X represents a coupling agent residue,
n represents an integer of 2 or more) and the like.

Further, the block C composed of other monomer components may be copolymerized within a range not impairing the gist of the present invention. The polystyrene-equivalent number average molecular weight of the block copolymer obtained by the method of the present invention can be appropriately adjusted depending on the application, etc., but is usually 10,000 to 2000.
000 range, preferably 11500-1,000,000
The range is more preferably 15,000 to 1,000,000.

Further, the block copolymer obtained by the method of the present invention is preferably hydrogenated from the viewpoint of improving heat deterioration resistance and weather resistance. The proportion of hydrogenation is not particularly limited, but at least 30% or more of the total carbon-carbon unsaturated double bond derived from the conjugated diene in the block copolymer may be hydrogenated, and preferably It is preferably hydrogenated at 50% or more, more preferably 80% or more.

The block copolymer may have a functional group such as a carboxyl group, a hydroxyl group, an acid anhydride, an amino group or an epoxy group in the molecular chain or at the terminal of the molecule, as long as the gist of the present invention is not impaired. May be included.

The block copolymer obtained by the method of the present invention includes, for example, an antioxidant, a softening agent, a plasticizer, an antistatic agent, a lubricant, an ultraviolet absorber, a flame retardant, a pigment, depending on the purpose of use. Various additives such as dyes and inorganic fillers can be added.

The block copolymer obtained by the method of the present invention has heat resistance, mechanical properties such as tensile strength at high temperature and tensile elongation, and relaxation of compression set, dynamic hysteresis and the like closer to vulcanized rubber. Various types of molded products, films / sheets, hoses / tubes, fibers, etc. can be produced by utilizing the characteristics of the block copolymer alone or as a composition or composite with a thermoplastic resin or a thermosetting resin. A molded product can be obtained and can be widely used in various fields of applications such as automobiles, electric / electronics, medical care, building materials, daily necessities / general goods.

[0046]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The chemicals used in the examples and specific examples had the highest purity available. The general solvent used in this example was sufficiently deaerated and dried.

The number average molecular weights of the polymers obtained in Examples and Comparative Examples are polystyrene conversion values measured by gel permeation chromatography (GPC). In addition, analysis of the composition and microstructure of the block copolymer was carried out by nuclear magnetic resonance spectrum measurement (1H-NM
R). Further, the polymerization conversion rate of α-methylstyrene was determined by quantifying the residual α-methylstyrene monomer by gas chromatography measurement.

The test methods used for various evaluations in the examples and comparative examples are as follows. (1) High temperature side tan δ (Tα) Wide range dynamic viscoelasticity measuring device DVE-V4F manufactured by Rheology Co.
Using the T Rheospectr, pull mode (11H
z), the peak temperature on the high temperature side of tan δ measured under the condition of the temperature rising rate of 3 ° C./min was read. (2) Hardness (JIS A) Measured at 25 ° C. according to JIS-K6301. (3) Melt flow rate (MFR) Measured at 230 ° C. under a load of 10 kg according to JIS-K7210. (4) Breaking strength Measured at 25 ° C and 80 ° C according to JIS-K6301. (5) Breaking elongation Measured at 25 ° C and 80 ° C according to JIS-K6301. (6) Compression set 80 ° C according to JIS-K6301, compression deformation 25%
The compressive deformation strain was measured when left for 22 hours under the above condition.

Example 1 Production of Polymer 1 (1) In an autoclave sufficiently replaced with nitrogen, α
-152 g of methylstyrene, 221 g of cyclohexane,
38.5 g of methylcyclohexane and 9.59 g of tetrahydrofuran were added. (2) Subsequently, 4.0 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at -10 ° C for 5 hours. When the number average molecular weight of poly α-methylstyrene (block A) 5 hours after the initiation of polymerization was measured by GPC, it was 30100 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 92%. (3) Next, 13 g of butadiene was added and stirred for 30 minutes to polymerize the block B1, then the temperature was raised to 10 ° C., and 109.1 g of cyclohexane was added. At this point, the polymerization addition rate of α-methylstyrene was 92%, the number average molecular weight of the polybutadiene block (B1) (GPC measurement, polystyrene conversion) was 5800, and 1,4 determined from 1H-NMR measurement The amount of binding was 17%. (4) Subsequently, 317 g of the reaction solution was taken out, and 524.3 g of cyclohexane was further added. (5) Next, add 97.5 g of 1,3-butadiene to obtain 60
The polymerization reaction was carried out at 0 ° C for 2 hours. The number average molecular weight (GPC measurement, polystyrene conversion) of the polybutadiene block (B2) of the polymer (structure: A-B1-B2) obtained by sampling at this point was 98100, and 1H-
The 1,4-bond amount obtained from the NMR measurement was 54%. (6) Subsequently, 0.5 of α, α′-dichloro-p-xylene was used.
1.7 ml of 0 M toluene solution was added and stirred at 60 ° C. for 1 hour to obtain a coupled α-methylstyrene-butadiene block copolymer. The coupling efficiency at this time is determined by the UV in GPC of the coupling body and the unreacted body.
It was 86% when calculated from the area ratio of (254 nm) absorption. The deactivation rate of the α-methylstyrene polymer block was 2.7%. As a result of 1 H-NMR analysis, α-
Methylstyrene polymer block content is 33%,
The entire butadiene polymer block (ie block B
The 1,4-bond content of 1 and block B2) was 52%.

(7) A hydrogenation catalyst was obtained by reacting a toluene solution containing 1.4 mmol of nickel octylate and 4.9 mmol of triisobutylaluminum at room temperature.
This was added to the solution of (6) above under a hydrogen atmosphere, the reaction was started from room temperature at a hydrogen gas pressure of 0.9 MPa, and the temperature was raised to 50 ° C. over 1 hour, and then the hydrogenation reaction was performed for 7 hours. It was (8) Citric acid 4.7 g, 30% hydrogen peroxide water 2.8 g
What was melt | dissolved in 100 ml of distilled water was thrown in in the reaction system of said (7), and after stirring at 50 degreeC for 2 hours, stirring was stopped and it left at room temperature. (9) The aqueous phase was extracted, the remaining organic phase was washed with distilled water three times, and then the organic phase was poured into acetone to reprecipitate the polymer. (10) The reprecipitate thus obtained was thoroughly washed with methanol, and then an antioxidant equivalent to 0.1 phr was added to 60
It was vacuum dried at ° C. (11) In this way, a hydrogenated product of an α-methylstyrene-butadiene block copolymer (Polymer 1) was obtained. As a result of GPC measurement of the obtained polymer 1, the main component was a block copolymer having the following molecular weight, and it was calculated from the area ratio of UV (254 nm) absorption in GPC. It turned out to be included. Mt (peak top of average molecular weight) = 268000 Mn (number average molecular weight) = 263000 Mw (weight average molecular weight) = 270100 Mw / Mn = 1.03 Further, 1H-NMR measurement of polymer 1 shows that block B1 and block B2 are derived. It was found that the hydrogenation rate of the butadiene portion of was 99%.

Example 2 Production of Polymer 2 (1) In an autoclave sufficiently replaced with nitrogen, α
-Methylstyrene 90.9 g, cyclohexane 132
g, methylcyclohexane 23.1 g and tetrahydrofuran 3.11 g were added. (2) Subsequently, 2.6 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at -10 ° C for 3 hours. When the number average molecular weight of poly α-methylstyrene (block A) 3 hours after the initiation of polymerization was measured by GPC method, it was 20400 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 73%. (3) Next, 10.5 g of butadiene was added and stirred for 30 minutes to polymerize block B1, then the temperature was raised to 10 ° C., and 109 g of cyclohexane was added. At this point, the polymerization addition rate of α-methylstyrene was 73%, the number average molecular weight of the polybutadiene block (B1) (GPC measurement, polystyrene conversion) was 9400, and 1,4 determined from 1H-NMR measurement The amount of binding was 25%. (4) Subsequently, 268 g of cyclohexane was added to the reaction solution for dilution, 235 g of the polymer solution was withdrawn, and 319 g of cyclohexane was added for dilution. (5) Next, add 26.0 g of 1,3-butadiene, and add 40
The polymerization reaction was carried out at 0 ° C for 2 hours. (6) Add 22.1 g of 1,3-butadiene and add 4
The polymerization reaction was carried out at 0 ° C. for 2 hours. The number average molecular weight (GPC measurement, polystyrene conversion) of the polybutadiene block (B2) of the polymer (structure: A-B1-B2) obtained by sampling at this point was 58700, and 1H-
The 1,4-bond content determined from NMR measurement was 48%. (7) Subsequently, 1.7 ml of a 0.50 M toluene solution of phenyl benzoate was added, and the mixture was stirred at 40 ° C. for 1 hour to obtain a coupled α-methylstyrene-butadiene block copolymer. The coupling efficiency at this time was 95% when calculated from the area ratio of UV absorption in the GPC of the coupled product and the unreacted product. The deactivation rate of the α-methylstyrene polymer block was 2.3%. 1H-N
As a result of the MR analysis, the content of the α-methylstyrene polymer block was 33%, and the content of the butadiene polymer block (that is, the block B1 and the block B2) was 1,
The amount of 4-bond was 45%.

(8) A hydrogenation catalyst was obtained by reacting a toluene solution of 2.7 mmol of nickel octylate and 9.5 mmol of triisobutylaluminum at room temperature.
This was added to the solution of (7) above under a hydrogen atmosphere, the reaction was started from room temperature at a hydrogen gas pressure of 0.9 MPa, heated to 60 ° C. for 10 minutes, and then a hydrogenation reaction was performed for 7 hours. It was (9) Citric acid 8.9 g, 30% hydrogen peroxide water 5.3 g
What was melt | dissolved in 100 ml of distilled water was thrown in in the reaction system of said (8), and after stirring at 50 degreeC for 2 hours, stirring was stopped and it left at room temperature. (10) The aqueous phase is extracted and the remaining organic phase is diluted with distilled water to 3
After batch washing, the organic phase was methanol / acetone = 1
The polymer was reprecipitated by pouring it into a mixed solvent of 1/1. (11) The reprecipitate thus obtained is thoroughly washed with methanol, and then an antioxidant equivalent to 0.1 phr is added to 60
It was vacuum dried at ° C. (12) In this way, a hydrogenated product of an α-methylstyrene-butadiene block copolymer (Polymer 2) was obtained. As a result of GPC measurement of the obtained polymer 2, the main component was a block copolymer having the following molecular weight, and it was calculated from the area ratio of UV (254 nm) absorption in GPC. It turned out to be included. Mt (peak top of average molecular weight) = 177000 Mn (number average molecular weight) = 173000 Mw (weight average molecular weight) = 175000 Mw / Mn = 1.01 Further, by 1H-NMR measurement of polymer 2, it was derived from block B1 and block B2. It was found that the hydrogenation rate of the butadiene portion of was 99%.

Example 3 Production of Polymer 3 (1) In an autoclave sufficiently replaced with nitrogen, α
-Methylstyrene 90.9 g, cyclohexane 132
g, hexane 23.1 g and tetrahydrofuran 3.
11 g was added. (2) Subsequently, 9.1 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was performed at -10 ° C for 3 hours. When the number average molecular weight of poly α-methylstyrene (block A) 3 hours after the initiation of polymerization was measured by GPC method, it was 6400 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 91%. (3) Next, 19.5 g of butadiene was added and stirred for 30 minutes to polymerize the block B1, then the temperature was raised to 10 ° C., and 308 g of cyclohexane was added. At this point, the polymerization addition rate of α-methylstyrene was 91%, the number average molecular weight of the polybutadiene block (B1) (GPC measurement, polystyrene conversion) was 3700, and 1,4 determined from 1H-NMR measurement The amount of binding was 13%. (4) 356 g of the polymerization solution was extracted, and 268 g of cyclohexane was further added for dilution. (5) Next, add 32.5 g of 1,3-butadiene, and add 40
The polymerization reaction was carried out at 0 ° C for 2 hours. (6) Add 29.3 g of 1,3-butadiene and add 4
The polymerization reaction was carried out at 0 ° C. for 2 hours. The number average molecular weight (GPC measurement, polystyrene conversion) of the polybutadiene block (B2) of the polymer (structure: A-B1-B2) obtained by sampling at this point was 27050, which was 1H-
The 1,4-bond amount obtained from the NMR measurement was 52%. (7) Subsequently, 4.1 ml of a 0.50 M toluene solution of phenyl benzoate was added and stirred at 40 ° C. for 1 hour to obtain a coupled α-methylstyrene-butadiene block copolymer. The coupling efficiency at this time was 94% when calculated from the area ratio of UV absorption in the GPC of the coupled product and the unreacted product. The deactivation rate of the α-methylstyrene polymer block was 1% or less. Also, 1
As a result of 1 H-NMR analysis, the α-methylstyrene polymer block content was 33%, and the 1,4-bond content of the entire butadiene polymer block (that is, block B1 and block B2) was 47%.

(8) A hydrogenation catalyst was obtained by reacting a toluene solution of 2.7 mmol of nickel octylate and 9.5 mmol of triisobutylaluminum at room temperature.
This was added to the solution of (7) above under a hydrogen atmosphere, the reaction was started from room temperature at a hydrogen gas pressure of 0.9 MPa, heated to 60 ° C. for 10 minutes, and then a hydrogenation reaction was performed for 7 hours. It was (9) Citric acid 8.9 g, 30% hydrogen peroxide water 5.3 g
What was melt | dissolved in 100 ml of distilled water was thrown in in the reaction system of said (8), and after stirring at 50 degreeC for 2 hours, stirring was stopped and it left at room temperature. (10) The aqueous phase is extracted and the remaining organic phase is diluted with distilled water to 3
After batch washing, the organic phase was methanol / acetone = 1
The polymer was reprecipitated by pouring it into a mixed solvent of 1/1. (11) The reprecipitate thus obtained is thoroughly washed with methanol, and then an antioxidant equivalent to 0.1 phr is added to 60
It was vacuum dried at ° C. (12) In this way, a hydrogenated product of an α-methylstyrene-butadiene block copolymer (Polymer 3) was obtained. As a result of GPC measurement of the obtained polymer 2, the main component was a block copolymer having the following molecular weight, and when calculated from the area ratio of UV (254 nm) absorption in GPC, the coupling product was 94% of the whole. It turned out to be included. Mt (peak top of average molecular weight) = 74300 Mn (number average molecular weight) = 72200 Mw (weight average molecular weight) = 73900 Mw / Mn = 1.01 Further, 1H-NMR measurement of polymer 3 resulted in block B1 and block B2. It was found that the hydrogenation rate of the butadiene portion of was 99%. For polymer 3, high temperature side tan-δ (Tα), hardness (JIS A),
Melt flow rate, breaking strength, breaking elongation and compression set were measured. The results are shown in Table 1. The viscoelastic behavior of polymer 3 is shown in FIG. In addition, the measurement of viscoelasticity is a wide-area dynamic viscoelasticity measuring device DVE-V4 made by Rheology
Using FT Rheospectr, pull mode (11H
z) and the temperature rising rate was 3 ° C./min.

Example 4 Production of Polymer 4 (1) In an autoclave sufficiently replaced with nitrogen, α
-Methyl styrene 90.9 g, cyclohexane 132.
4 g, methylcyclohexane 23.1 g and tetrahydrofuran 5.8 g were added. (2) Subsequently, 2.8 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at -10 ° C for 3 hours. When the number average molecular weight of poly α-methylstyrene (block A) 3 hours after the initiation of polymerization was measured by GPC method, it was 28500 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 95%. (3) Next, 6.5 g of 1,3-butadiene was added, and the mixture was stirred for 1 hour to polymerize block B1 and then the temperature was raised to 10 ° C., 156 g of cyclohexane was added, and a polymerization solution of 300 m was added.
I pulled out l. Further, 156 g of cyclohexane was added.
The polymerization addition rate of α-methylstyrene at this point is 95%.
And the number average molecular weight (GPC measurement, polystyrene conversion) of the polybutadiene block (B1) was 7,000, and the 1,4-bond amount obtained from 1H-NMR measurement was 9%.
Met. (4) 200 ml of the polymerization solution was extracted, and 428 g of cyclohexane was further added. (5) Subsequently, 58.5 g of 1,3-butadiene was added and 4
The polymerization reaction was carried out at 5 ° C. for 3 hours. The number average molecular weight (GPC measurement, polystyrene conversion) of the polybutadiene block (B2) of the polymer (structure: A-B1-B2) obtained by sampling at this point was 180500, and 1H.
The amount of 1,4-bond determined from NMR measurement was 60%. (6) Next, 13.6 g of styrene was added and a polymerization reaction was performed at 45 ° C. for 2 hours, and then the polymerization reaction was stopped by adding methanol to obtain an α-methylstyrene-butadiene-styrene block copolymer. . The deactivation rate of the α-methylstyrene polymer block was 2.7% when calculated from the area ratio of UV absorption in GPC. As a result of 1 H-NMR measurement, the content of α-methylstyrene polymer block and styrene polymer block of this product was 31% in total, and 1,4 of the entire butadiene polymer block (that is, block B1 and block B2) was obtained. -58% binding
Met.

(7) A hydrogenation catalyst was obtained by reacting a toluene solution of nickel octylate (2.7 mmol) and triisobutylaluminum (9.5 mmol) at room temperature.
This was added to the solution of (6) above under a hydrogen atmosphere, the reaction was started from room temperature at a hydrogen gas pressure of 0.9 MPa, heated to 60 ° C. for 10 minutes, and then a hydrogenation reaction was performed for 6 hours. It was (8) Citric acid 8.9g, 30% hydrogen peroxide water 5.3g
What was melt | dissolved in 100 ml of distilled water was thrown in in the reaction system of said (7), and after stirring at 50 degreeC for 2 hours, stirring was stopped and it left at room temperature. (9) The aqueous phase was extracted, the remaining organic phase was washed with distilled water three times, and then the organic phase was methanol / acetone = 1 /
The polymer was reprecipitated by pouring it into the mixed solvent of 1. (10) The reprecipitate thus obtained was thoroughly washed with methanol, and then an antioxidant equivalent to 0.1 phr was added to 60
It was vacuum dried at ° C. (11) In this way, a hydrogenated product of an α-methylstyrene-butadiene block copolymer (polymer 4) was obtained. As a result of analyzing the obtained polymer 4 by GPC, the molecular weight was as shown below. Mt (peak top of average molecular weight) = 263000 Mn (number average molecular weight) = 258000 Mw (weight average molecular weight) = 265000 Mw / Mn = 1.03 Further, as a result of analyzing polymer 4 by 1H-NMR, block B1 and It was found that the hydrogenation rate of the butadiene portion derived from block B2 was 97%.

Comparative Example 1 α-Methylstyrene was polymerized in the same manner as in Example 4 except that the polymerization temperature was changed to 35 ° C. (1) In an autoclave sufficiently replaced with nitrogen, α
-Methyl styrene 90.9 g, cyclohexane 132.
4 g, methylcyclohexane 23.1 g and tetrahydrofuran 5.8 g were added. (2) Subsequently, 2.8 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at 35 ° C. for 3 hours. When the number average molecular weight of poly α-methylstyrene 3 hours after the initiation of the polymerization was measured by the GPC method,
It was 1100 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 5%, which was extremely low. Further, even if the polymerization time was set to 24 hours, the polymerization conversion could not be increased.

Comparative Example 2 (1) In an autoclave sufficiently replaced with nitrogen, α
-Methyl styrene 90.9 g, cyclohexane 161.
3 g was added. (2) Subsequently, 2.8 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at 60 ° C. for 1 hour. When the number average molecular weight of poly α-methylstyrene 1 hour after the initiation of polymerization was measured by the GPC method,
It was 800 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was 3%, which was extremely low. Further, even if the polymerization time was set to 24 hours, the polymerization conversion could not be increased.

Comparative Example 3 α-Methylstyrene was polymerized in the same manner as in Example 4 except that the amount of tetrahydrofuran added was reduced. (1) In an autoclave sufficiently replaced with nitrogen, α
-Methyl styrene 90.9 g, cyclohexane 132.
4 g, methylcyclohexane 23.1 g and tetrahydrofuran 0.2 g were added. (2) Subsequently, 2.8 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at -10 ° C for 3 hours. The polymerization conversion rate of α-methylstyrene 3 hours after the initiation of the polymerization was extremely low at 2%, and polyα-methylstyrene was not obtained.

Comparative Example 4 α-Methylstyrene was polymerized in the same manner as in Example 4 except that the concentration of α-methylstyrene was lowered. (1) In an autoclave sufficiently replaced with nitrogen, α
-Methylstyrene 9.1 g, cyclohexane 156.0
g, methylcyclohexane 27.2 g and tetrahydrofuran 6.8 g were added. (2) Subsequently, 0.3 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was performed at -10 ° C for 3 hours. When the number average molecular weight of poly α-methylstyrene 3 hours after the initiation of polymerization was measured by the GPC method, it was 7200 in terms of polystyrene, and the polymerization conversion rate of α-methylstyrene was as low as 24%.

Comparative Example 5 As a target of comparison of physical properties, a hydrogenated product of a styrene-butadiene-styrene triblock copolymer was produced. (1) 23.2 g of styrene and 640.0 g of cyclohexane were put into an autoclave which had been sufficiently replaced with nitrogen. (2) Subsequently, 2.3 ml of a 1.3 M cyclohexane solution of sec-butyllithium was added, and a polymerization reaction was carried out at 40 ° C. for 2 hours. (3) Next, 1.6 g of tetrahydrofuran and 1,3-
113.6 g of butadiene was added, and the mixture was stirred at 60 ° C. for 2 hours. (4) Next, 23.2 g of styrene was added and a polymerization reaction was carried out at 45 ° C. for 2 hours, and then the polymerization reaction was stopped by adding methanol to obtain a styrene-butadiene-styrene triblock copolymer. As a result of 1 H-NMR measurement, it was found that the content of the styrene polymer block was 29% and the content of 1,4-bond in the butadiene polymer block was 60%.

(7) A hydrogenation catalyst was obtained by reacting a toluene solution of nickel octylate (1.5 mmol) and triisobutylaluminum (5.3 mmol) at room temperature.
This is added to the solution of (6) above under a hydrogen atmosphere, the reaction is started from room temperature at a hydrogen gas pressure of 0.9 MPa, and after heating to 60 ° C. for 10 minutes, the hydrogenation reaction is performed for 6 hours. went. (8) Citric acid 5.0 g, 30% hydrogen peroxide water 3.0 g
What was melt | dissolved in 100 ml of distilled water was thrown in in the reaction system of said (7), and after stirring at 50 degreeC for 2 hours, stirring was stopped and it left at room temperature. (9) The aqueous phase was extracted, the remaining organic phase was washed with distilled water three times, and then the organic phase was methanol / acetone = 1 /
The polymer was reprecipitated by pouring it into the mixed solvent of 1. (10) The reprecipitate thus obtained was thoroughly washed with methanol, and then an antioxidant equivalent to 0.1 phr was added to 60
It was vacuum dried at ° C. (11) Thus, a hydrogenated product of styrene-butadiene block copolymer (Polymer 5) was obtained. As a result of analyzing the obtained polymer 5 by GPC, the molecular weight was as shown below. Mt (peak top of average molecular weight) = 126000 Mn (number average molecular weight) = 80700 Mw (weight average molecular weight) = 847,000 Mw / Mn = 1.05 Moreover, the polymer 5 was analyzed by 1H-NMR, and a butadiene polymer was obtained. It was found that the hydrogenation rate of the block part was 98%. For polymer 5, high temperature side tan-
δ (Tα), hardness (JIS A), melt flow rate, breaking strength, breaking elongation and compression set were measured. The results are shown in Table 1.

[0063]

[Table 1]

The viscoelastic behavior of polymer 5 is shown in FIG. The viscoelasticity is measured in the same manner as in the case of polymer 3,
Rheology wide dynamic viscoelasticity measuring device DVE-V4F
Using the T Rheospectr, pull mode (11H
z) and the temperature rising rate was 3 ° C./min.

[0065]

According to the present invention, by adopting a novel production method, a polymer block mainly composed of α-methylstyrene units and a different polymer block mainly composed of conjugated diene units having a specific structure are copolymerized. By polymerizing, it has become possible to provide a block copolymer having both excellent high-temperature characteristics and rubber-like properties. The block copolymer obtained by the method of the present invention has heat resistance, mechanical properties such as tensile strength at high temperature and tensile elongation,
By making use of relaxation characteristics such as compression set and dynamic hysteresis, which are closer to those of vulcanized rubber, block copolymers alone, compositions with thermoplastic resins and thermosetting resins, etc. Various molded products such as film, sheet, hose, tube, and fiber can be obtained, and can be widely used in various fields such as automobiles, electric / electronics, medical care, building materials, daily necessities / general goods.

[Brief description of drawings]

FIG. 1 Polymer 3 obtained in Example 3 and Comparative Example 5
It is a figure which shows the viscoelastic behavior about the polymer 5 obtained by.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromichi Nakata             41 Miyukigaoka, Tsukuba City, Ibaraki Prefecture Co., Ltd.             Kuraray F-term (reference) 4J026 HA06 HA26 HA32 HA39 HA49                       HB14 HB15 HB16 HB32 HB39                       HB45 HB48 HC06 HC14 HC15                       HC16 HC32 HC39 HC46 HC50                       HE01 HE04 HE05

Claims (3)

[Claims] 1. Using an organolithium compound in a nonpolar solvent as an initiator, in the presence of a polar compound at a concentration of 0.1 to 10% by mass, at a temperature of -30 ° C. to 30 ° C., 5 to 50% by mass. After polymerizing α-methylstyrene at a concentration of 1 and then polymerizing the obtained polymer block A with a conjugated diene in an amount of 1 to 100 molar equivalents to living poly α-methylstyryllithium to form a polymer block B1. , A polymer block B by further polymerizing a conjugated diene at a temperature higher than 30 ° C.
A method for producing a block copolymer, which comprises forming 2 and, if necessary, reacting a polyfunctional coupling agent and hydrogenating. 2. An organic lithium compound in a non-polar solvent is used as an initiator in the presence of a polar compound at a concentration of 0.1 to 10% by mass at a temperature of -30 to 30 ° C. in an amount of 5 to 50% by mass. After polymerizing α-methylstyrene at a concentration of 1 and then polymerizing the obtained polymer block A with a conjugated diene in an amount of 1 to 100 molar equivalents to living poly α-methylstyryllithium to form a polymer block B1. , A polymer block B by further polymerizing a conjugated diene at a temperature higher than 30 ° C.
After forming 2, α is added to the living polymer obtained.
-A method for producing a block copolymer, which comprises polymerizing an anion-polymerizable monomer other than methylstyrene and hydrogenating it if necessary. 3. The block copolymer obtained has at least one block structure A-B1-B2 consisting of the following block A, block B1 and block B2, and is derived from a conjugated diene unit constituting block B1 and block B2. 3. The method according to claim 1, wherein the carbon-carbon unsaturated double bond is a block copolymer in which at least a part of the carbon-carbon unsaturated double bond may be hydrogenated. Block A: a polymer block mainly composed of α-methylstyrene units and having a number average molecular weight of 1,000 to 300,000, and block B1: mainly composed of a conjugated diene unit and having a number average molecular weight of 500 to 10,000, and
Polymer block having a 4-bond content of less than 30%, block B2: a polymer block mainly composed of a conjugated diene unit, having a number average molecular weight of 10,000 to 400,000, and having a 1,4-bond content of 30% or more. United block.