JP2008001819A - Method for producing hydrogenated block copolymer imparted with polar functional group and the hydrogenated block copolymer imparted with polar functional group - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a hydrogenated block copolymer imparted with a polar functional group by imparting the polar functional group to the hydrogenated material of an aromatic vinyl compound-based block copolymer having a specific structural unit, and the hydrogenated block copolymer imparted with the polar functional group. <P>SOLUTION: This method for producing the hydrogenated block copolymer imparted with the polar functional group is provided by hydrogenating the aromatic vinyl compound-based block copolymer having ≥1 polymer block A consisting mainly of an aromatic vinyl compound containing a methylstyrene-derived structural unit (a) obtained by bonding at least one methyl group with a benzene ring, and ≥1 polymer block B consisting mainly of a conjugated diene compound in the presence of a hydrogenation catalyst to obtain a hydrogenated block copolymer, effecting an organo-alkali metal compound on the hydrogenated block copolymer in the presence of a base to form an anion by drawing out a hydrogen atom of methyl group on an aromatic ring and then reacting a polar functional group-imparting agent on the anionized hydrogenated block copolymer. The hydrogenated block copolymer imparted with the polar functional group is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an aromatic vinyl compound-based block copolymer containing a structural unit (a) derived from methylstyrene having at least one methyl group bonded to a benzene ring (hereinafter sometimes abbreviated as structural unit (a)). Water having a polar functional group formed by adding a polar functional group to a hydrogenated product of a coalescence (hereinafter sometimes simply referred to as “hydrogenated block copolymer (I ₀ )” in the present specification) The present invention relates to a method for producing a hydrogenated block copolymer, and a hydrogenated block copolymer to which the polar functional group is imparted.
More specifically, the present invention relates to a hydrogenated block copolymer provided with a polar functional group at a specific position and a method for producing the same.

  Conventionally, an aromatic vinyl compound block copolymer or a hydrogenated product thereof is a raw material for various thermoplastic elastomer compositions, a resin modifier, taking advantage of its excellent mechanical properties, elasticity, flexibility, adhesiveness, etc. It is used for adhesives. However, since such aromatic vinyl compound block copolymers or hydrogenated products thereof are nonpolar, they generally have affinity with nonpolar materials such as polyolefins, polystyrenes, petroleum softeners, etc., but polyacetal resins It has no affinity for polar materials such as engineering plastics such as polyamide resin, polycarbonate resin, polybutylene terephthalate and polyetheretherketone. In general, many of these engineering plastics have better heat resistance than aromatic vinyl compound block copolymers, and aromatic vinyl compound block copolymers or their hydrogenated resins are used as resin modifiers. Adding an object is disadvantageous from the aspect of affinity, and has problems such as a decrease in heat resistance. For this reason, it is desired to impart polarity and heat resistance to the aromatic vinyl compound block copolymer or a hydrogenated product thereof.

As a method for introducing a polar functional group into a molecule in order to impart polarity to an aromatic vinyl compound-based (co) polymer, for example, [1] When anionic polymerization of styrene using sec-butyllithium as a polymerization initiator A method in which ethylene oxide is added to poly (styryl) lithium, and water is added to introduce a hydroxyl group at the molecular end (see Non-Patent Document 1);
[2] When an aromatic vinyl compound and a conjugated diene compound are sequentially polymerized in an inert organic solvent such as n-hexane or cyclohexane using an alkyl lithium compound as an initiator, ethylene oxide is obtained when the desired molecular structure and molecular weight are reached. , A compound having an oxirane skeleton such as propylene oxide and styrene oxide, or a lactone compound such as ε-caprolactone, β-propiolactone, dimethylpropiolactone (pivalolactone), and the like, and then alcohols, carboxylic acids, water A method of adding an active hydrogen-containing compound such as to stop the polymerization and introducing a hydroxyl group at the molecular end (see Patent Document 1);
[3] At least one aromatic vinyl compound block copolymer having an olefin compound polymer block whose degree of unsaturation does not exceed 20% and an unsaturated carboxylic acid or a derivative thereof are radicalized in an extruder. The reaction is carried out in the presence of an initiator, and the added amount of unsaturated carboxylic acid or derivative thereof is 0.05 to 20 parts by mass per 100 parts by mass of the block copolymer, and the toluene insoluble matter is 0.05 mass. % Of a method for producing a modified block copolymer that is not more than% (see Patent Document 2);
Etc.

Journal of Polymer Science, Part A Polymer Chemistry (J. Polym. Sci. Part A Polym. Chem.), 26, 2031-2037 (1998) JP-A-10-57527, paragraph 0018, etc. JP 63-81113 A, Claims, etc.

However, the introduction of the polar functional group into the molecular chain by the methods [1] and [2] is limited to the terminal. Since introduction of a functional group is impossible, the effect of imparting polarity is small. In the method [3], the site where the polar functional group can be introduced is limited to the olefin compound polymer block, and the types of polar functional groups that can be introduced are also limited. Moreover, since it is difficult to wash the resulting modified block copolymer in the reaction process, there is a problem that by-products and unreacted substances cannot be removed and remain mixed.
Thus, the object of the present invention is to provide polar functional groups having polarity and heat resistance by imparting polar functional groups to the hydrogenated aromatic vinyl compound block copolymer containing the structural unit (a). It is to provide a method for producing a hydrogenated block copolymer imparted with a hydrogenated block copolymer and a hydrogenated block copolymer imparted with the polar functional group.

According to the present invention, the above object is
[1] Polymer block A mainly composed of an aromatic vinyl compound containing a structural unit (a) derived from methylstyrene having at least one methyl group bonded to a benzene ring [hereinafter abbreviated as structural unit (a)]. And an aromatic vinyl compound block copolymer [hereinafter abbreviated as block copolymer (I ₀ )] having at least one polymer block and at least one polymer block B mainly composed of a conjugated diene compound. A hydrogenated block copolymer obtained by hydrogenation in the presence [hereinafter abbreviated as block copolymer (I ₁ )] is reacted with an organic alkali metal compound in the presence of a base to form methyl on the benzene ring. A polar functional group is added, characterized in that a hydrogen atom of the group is extracted to form an anion, and then the anionized hydrogenated block copolymer is reacted with a polar functional group-imparting agent. A hydrogenated block copolymer [hereinafter abbreviated as block copolymer (I)]; and [2] by providing block copolymer (I) obtained by the method of [1]. Achieved.

According to the present invention, it becomes possible to introduce a plurality of polar functional groups into the polymer block A mainly composed of the aromatic vinyl compound of the block copolymer (I ₁ ). For example, a block copolymer (I) excellent in tensile permanent elongation at 70 ° C. can be provided.

The present invention is described in detail below.
In the polymer block A of the block copolymer (I ₀ ), examples of methylstyrene constituting the structural unit (a) include o-methylstyrene, m-methylstyrene, p-methylstyrene, and 2,4-dimethylstyrene. 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, 3,4,5-trimethylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5-ethylstyrene, and the like. The polymer block A may be comprised only from 1 type of these structural units (a), and may be comprised from 2 or more types. Among these, a structural unit derived from p-methylstyrene is preferable.

The polymer block A corresponds to the hard segment of the block copolymer (I ₀ ), and the methyl group bonded to the benzene ring in the structural unit (a) is extracted by the action of an organic alkali metal compound. This is a site where a polar functional group is introduced.

The proportion of the structural unit (a) in the polymer block A, the block copolymer weight of the polymer block A constituting the (I ₀₎ [block copolymer (I ₀₎ is 2 or more polymer blocks A If present, the total mass] is preferably 1% by mass or more, more preferably 10% by mass or more, further preferably 40% by mass or more, and all units are structural units (a ). When the proportion of the structural unit (a) is less than 1% by mass, the polar functional group tends not to be introduced into the polymer block A. The bonding form of the structural unit (a) and the other aromatic vinyl compound unit in the polymer block A may be any form such as random, block, and tapered.

  Examples of the aromatic vinyl compound unit other than the structural unit (a) include units composed of styrene, α-methylstyrene, β-methylstyrene, monofluorostyrene, difluorostyrene, methoxystyrene, vinylnaphthalene, vinylanthracene, indene and the like. Among them, a unit composed of styrene is preferable.

The block copolymer (I ₀ ) comprises a polymer block A composed of aromatic vinyl compound units containing the structural unit (a) and a polymer composed of aromatic vinyl compound units not containing the structural unit (a). You may have a united block.

The content of the polymer block A is preferably in the range of 10 to 40% by mass with respect to the total constituent amount of the block copolymer (I ₀ ). When the content is lower than 10% by mass, the cohesive force as a hard segment of the polymer block A is not sufficient, and the pseudo-crosslinking points are not sufficiently formed. Therefore, the block copolymer (I) has sufficient heat resistance (for example, 70 ° C. It tends to show no elasticity recovery property. Moreover, when larger than 40 mass%, the thermoplastic elastomer consisting of block copolymer (I) tends to lack flexibility.

The polymer block A may have a small amount of structural units composed of other polymerizable monomers as necessary together with the structural units composed of the aromatic vinyl compound containing the structural unit (a). In this case, the proportion of structural units composed of other polymerizable monomers is such that the mass of the polymer block A constituting the block copolymer (I ₀ ) [the aromatic vinyl compound block copolymer (I ₀ ) is In the case of having two or more polymer blocks A, the total mass] is preferably 20% by mass or less, and more preferably 10% by mass or less. Examples of other polymerizable monomers in that case include butadiene and isoprene.

On the other hand, examples of the conjugated diene compound constituting the polymer block B in the block copolymer (I ₀ ) include butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1, Examples include 3-hexadiene. The polymer block B may be comprised only from 1 type of these conjugated diene compounds, and may be comprised from 2 or more types. Among these, it is preferable to be composed of butadiene, isoprene or a mixture of butadiene and isoprene. The type and content of the microstructure of the polymer block B are not particularly limited. Further, when two or more kinds of conjugated diene compounds are used in combination, their bonding form can be random, block, tapered, or a combination of two or more thereof.

  As described above, the polymer block B is preferably a polyisoprene block composed of isoprene units, a polybutadiene block composed of butadiene units, or a copolymer block composed of a mixture of isoprene units and butadiene units.

The polymer block B may have a small amount of a structural unit composed of another polymerizable monomer as necessary, together with a structural unit composed of a conjugated diene compound. In that case, the proportion of other polymerizable monomer, the weight of the polymer block B constituting the block copolymer (I ₀₎ [block copolymer (I ₀₎ is 2 or more polymer blocks B When it has, it is preferable that it is 30 mass% or less based on the total mass], and it is more preferable that it is 10 mass% or less. Examples of other polymerizable monomer in that case include styrene, α-methylstyrene, p-methylstyrene, and the like.

As long as the polymer block A and the polymer block B are bonded to each other, the block copolymer (I ₀ ) is not limited in its bonding mode, and is linear, branched, radial, or two of them. Any of the above combined forms may be used. Especially, it is preferable that the coupling | bonding type of the polymer block A and the polymer block B is a linear form, when the polymer block A is represented by A and the polymer block B is represented by B, for example, AB- Examples thereof include a triblock copolymer represented by A, a tetrablock copolymer represented by ABABA, and a pentablock copolymer represented by ABABA. Among these, a triblock copolymer (ABA) is preferable from the viewpoint of ease of production of the block copolymer (I ₀ ).

The number average molecular weight of the block copolymer (I ₀ ) is not particularly limited, but is preferably in the range of 30000 to 1000000, more preferably in the range of 40000 to 300000. In addition, the number average molecular weight here means the number average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC).

The block copolymer (I ₀ ) can be produced, for example, by the following known anionic polymerization method. That is, methylstyrene constituting the structural unit (a) or methylstyrene constituting the structural unit (a) in an organic solvent inert to the polymerization reaction such as n-hexane or cyclohexane using an alkyl lithium compound as an initiator. And a mixture of an aromatic vinyl compound and a conjugated diene compound are sequentially polymerized to form a block copolymer (I ₀ ).

From the reaction mixture containing the block copolymer (I ₀ ), preferably, without isolating the block copolymer (I ₀ ), a hydrogenation catalyst is subsequently added and hydrogenated in a hydrogen atmosphere to block the block copolymer. The union (I ₁ ) can be obtained. This hydrogenation reaction is a Ziegler system comprising a combination of an organometallic compound composed of a Group 9 or 10 metal such as nickel or cobalt and an organoaluminum compound or organolithium compound such as triethylaluminum or triisobutylaluminum as a hydrogenation catalyst. Catalyst: In the presence of a metallocene catalyst comprising a combination of a bis (cyclopentadienyl) compound of a transition metal such as titanium, zirconium or hafnium and an organometallic compound comprising lithium, sodium, potassium, aluminum, zinc or magnesium. Usually, the reaction temperature is 20 to 100 ° C. and the hydrogen pressure is 0.1 to 10 MPa.

In the block copolymer (I), when the functional group is introduced into the polymer block A rather than the polymer block B, the heat resistance (for example, elasticity at 70 ° C.) of the obtained block copolymer (I). (Recoverability) tends to be excellent. In the block copolymer (I ₁ ), the higher the hydrogenation rate, the higher the proportion of functional groups introduced into the polymer block A. Therefore, the hydrogenated polymer constituting the block copolymer (I ₁ ) 95% or more of the carbon-carbon double bonds based on the conjugated diene compound unit of the combined block B are preferably hydrogenated, more preferably 98% or more, and 99% or more hydrogenated. Is more preferable.
In addition, the hydrogenation rate of the carbon-carbon double bond based on the conjugated diene compound unit of the polymer block B that has been hydrogenated is determined by hydrogenation using a measuring means such as iodine titration, infrared spectrophotometer, or nuclear magnetic resonance. The amount of the carbon-carbon double bond in the polymer block B before and after the reaction can be measured and calculated from the measured value.

A base is preferably added to the reaction mixture from the reaction mixture containing the block copolymer (I ₁ ) thus obtained, preferably without isolating the block copolymer (I ₁ ). In the presence, an organic alkali metal compound is allowed to act to extract a hydrogen atom of a methyl group on the benzene ring of the structural unit (a) to form an anion, and then the anionized hydrogenated block copolymer (I ₁ ) In addition, the block copolymer (I) can be obtained by reacting the polar functional group-imparting agent. In addition, the block copolymer (I ₁ ) is distilled off from the reaction mixture containing the block copolymer (I ₁ ) by distilling off the solvent in a short time by blowing high-temperature steam such as a steam stripping method, After isolation once by a known polymer isolation means from a polymer solution such as a reprecipitation method in which a reaction mixture is added to a poor solvent of a block copolymer (I ₁ ) such as methanol or acetone for precipitation. The block copolymer (I) may be obtained by carrying out the reaction described above, but the former method is simpler. Hereinafter, this reaction will be described.

  Examples of the organic alkali metal compound include methyl lithium, ethyl lithium, n-propyl lithium, i-propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, phenyl lithium, α-naphthyl lithium, β-naphthyl. Lithium, allyl lithium, benzyl lithium and the like can be mentioned. These alkyl metals may be used alone or in combination of two or more. Of these, n-butyllithium, sec-butyllithium, and tert-butyllithium are preferable.

  The amount of the organic alkali metal compound added can be appropriately adjusted depending on the number of polar functional groups to be introduced. From the viewpoint of effectively expressing the polarity and heat resistance, the amount added is 0 with respect to 1 mol of the structural unit (a). The range of 0.001 mol to 5 mol is preferable, and the range of 0.005 mol to 1 mol is more preferable.

  Examples of the base include ethers such as tetrahydrofuran, diethyl ether and dioxane; tertiary amines such as N, N, N ′, N′-tetramethylethylenediamine, triethylamine and hexamethyltriethylenetetramine; nitrogen-containing aromatics such as pyridine. Compound: Metal alkoxides such as potassium tert-butoxide, potassium tert-amyl alkoxide, potassium 1,1-dimethyl-1-butoxide and the like. These bases may be used alone or in combination of two or more. Of these, tetrahydrofuran, N, N, N ′, N′-tetramethylethylenediamine, and potassium tert-butoxide are preferable.

  The addition amount of the base is preferably 0.5 mol or more, more preferably in the range of 1 to 10 mol, relative to 1 mol of the organic alkali metal compound. When the amount is less than 0.5 mol, the anionization reaction of the methyl group on the benzene ring of the structural unit (a) tends not to occur sufficiently.

  The polar functional group-imparting agent is appropriately selected depending on the type of polar functional group to be introduced. For example, when introducing a carboxyl group, carbon dioxide is used, and when introducing a hydroxyl group, epoxides such as ethylene oxide, propylene oxide, and styrene oxide; aldehydes such as formaldehyde, acetaldehyde, and benzaldehyde; ketones such as acetone and benzophenone are listed. In the case of introducing an amino group, for example, imide such as ethyleneimide, vinylpyridine, ε-caprolactam, β-propiolactam, lactam such as dimethylpropiolactam, and the like are introduced, and a fluorine atom-containing group is introduced. In the case, for example, fluoroalkyl (meth) acrylates such as 2,2,2-trifluoroethyl acrylate and 2,2,3,3-tetrafluoropropyl acrylate, and fluorostyrene are exemplified. These may be used alone or in combination of two or more.

  The addition amount of the polar functional group-imparting agent is preferably 1 mol or more, more preferably in the range of 1 to 2 mol, relative to 1 mol of the organic alkali metal compound. When the amount is less than 1 mol, the polar functional group tends not to be sufficiently introduced.

The method for producing the block copolymer (I) of the present invention preferably does not isolate the block copolymer (I ₁ ) from the reaction mixture containing the block copolymer (I ₁ ) obtained by the above method. In the presence of the base, the organic alkali metal compound is added in the range of −50 to 80 ° C., preferably in the range of −20 to 60 ° C. for 30 to 300 minutes. A hydrogen atom of a methyl group on the benzene ring of the structural unit (a) to form an anion, and then the anionized hydrogenated block copolymer (I ₁ ) is added with a polar functional group-imparting agent. Is added and allowed to react at the same temperature, and if necessary, water, an inorganic acid aqueous solution or the like is added to stop the reaction, whereby the block copolymer (I) can be obtained. The reaction time varies depending on the type and amount of the polar functional group-imparting agent to be added, but is usually in the range of 1 to 60 minutes.

  The block copolymer (I) thus obtained is obtained from the reaction mixture by means usually used for isolating the polymer from the solution containing the polymer, for example, block copolymer such as methanol or acetone. It can isolate by applying the reprecipitation method etc. which add and precipitate a reaction liquid mixture to the poor solvent of unification | combination (I).

  The polar functional group content of the block copolymer (I) of the present invention is most suitable according to the type of polar functional group introduced, such as acid value titration, hydroxyl value titration, infrared spectrophotometer, nuclear magnetic resonance, etc. In addition, the concentration of polar functional groups per unit weight can be measured by a measurement means known per se, and the number of polar functional groups (f value) per molecule of the block copolymer (I) can be calculated from the measured value. . From the viewpoint of effectively expressing the polarity and heat resistance, the f value is very preferably 2 or more and 100 or less. When it is smaller than 2, the polarity and heat resistance of the block copolymer (I) tend to be hardly exhibited.

  In the case of an aromatic vinyl compound block copolymer, generally, when the ambient temperature becomes a temperature near the glass transition temperature of a polymer block composed of an aromatic vinyl compound that serves as a hard segment, the polymer block aggregates. Although the force is weakened and sufficient heat resistance is not exhibited, in the method of the present invention, a polar functional group can be introduced into the polymer block A serving as a hard segment, and the cohesive strength of the polymer block A is increased. Therefore, compared with the case where the polar functional group is introduced only into the polymer block B which plays a role as a soft segment, the hydrogenated block copolymer provided with the polar functional group of the present invention has a heat resistance ( For example, it has excellent elasticity recovery at 70 ° C.

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

Example 1
(1) In a pressure vessel equipped with a stirrer, 40 kg of cyclohexane and 250 ml of sec-butyllithium (11% by mass, cyclohexane solution) are added, and 1.5 kg of p-methylstyrene is added to this solution over 30 minutes at 50 ° C. Polymerization was conducted for 60 minutes, then 7.0 kg of a mixture of isoprene and butadiene (isoprene / butadiene = 50/50; mass ratio) was added over 60 minutes and polymerization was carried out at 50 ° C. for 90 minutes, and 1.5 kg of p-methylstyrene was further added. Was added over 30 minutes and polymerized at 50 ° C. for 60 minutes to obtain a reaction mixture containing poly (p-methylstyrene-poly (isoprene / butadiene) -poly (p-methylstyrene) triblock copolymer. When a part of the reaction mixture was sampled and GPC analysis was performed, the number of poly p-methylstyrene-poly (isoprene / butadiene) -poly p-methylstyrene triblock copolymers contained in the reaction mixture was determined. The average molecular weight was 50000, while the p-methylstyrene content measured by ¹ H-NMR was 30% by mass.

(2) A hydrogenation catalyst prepared by diluting the above reaction mixture with 50 kg of cyclohexane and separately adding 350 g of triisopropylaluminum (20 mass%, cyclohexane solution) to 60 g of nickel octylate (64 mass%, cyclohexane solution). It was added to the reaction mixture and subjected to a hydrogenation reaction at 80 ° C. and a hydrogen pressure of 1 MPa for 3 hours to obtain the poly p-methylstyrene-poly (isoprene / butadiene) -poly p-methylstyrene triblock copolymer described above. Hydrogenated product [hereinafter abbreviated as block copolymer 1] ] Was obtained. A part of the reaction mixture was sampled and subjected to GPC analysis. As a result, the number average molecular weight of the block copolymer 1 contained in the reaction mixture was 51000, while p-measured by ¹ H-NMR. The hydrogenation rates of the carbon-carbon double bonds based on the methylstyrene content and the isoprene / butadiene units of the hydrogenated poly (isoprene / butadiene) block were 29% by mass and 99%, respectively.

(3) Next, 1.2 kg of tetrahydrofuran was added to the reaction mixture containing the block copolymer 1 and cooled to 50 ° C., and 1200 ml of tert-butyllithium (14% by mass, pentane solution) was added to the mixture. The solution was added so as to keep the temperature of the solution in the range of 40 to 60 ° C., and stirred at the same temperature for 3 hours after the addition. The reaction mixture was poured into 10 kg of cyclohexane in which 0.18 kg of carbon dioxide was dissolved at 50 ° C. for 30 minutes, reacted at 60 ° C. for 1 hour, and 1.6 kg of 10% by mass phosphoric acid aqueous solution was added. . The block copolymer 1 was isolated by reprecipitating the organic phase containing the block copolymer 1 with 200 kg of acetone.
A part of the obtained block copolymer (abbreviated as block copolymer (I) -1) was sampled and subjected to GPC analysis. As a result, the number average molecular weight of the block copolymer (I) -1 was obtained. Was 51,000.

(4) About 1 g of the obtained block copolymer (I) -1 was precisely weighed and placed in a 500 ml Erlenmeyer flask, and a solution obtained by dissolving 5 mg of phenolphthalein in 200 ml of toluene was added to the block copolymer ( I) -1 was completely dissolved. This solution was titrated with an ethanol solution of potassium hydroxide (0.05 mol / l). The f value (the number of polar functional groups per molecule of the block copolymer) was calculated from the amount dropped by the following formula. The results are shown in Table 1.
f value (pieces / molecule) = 0.05 × V × M
V: dripping amount of ethanol solution (0.05 mol / l) of potassium hydroxide (l)
M: Number average molecular weight of block copolymer (I) -1

(5) On the other hand, about 25 g of the obtained block copolymer (I) -1 was pressed with a hot press machine at 230 ° C. and 10 MPa for 3 minutes to prepare a sheet having a thickness of 0.1 cm. According to the method described in JIS K 6262, a strip-shaped test piece No. 2 was punched out from the obtained sheet, and a 2 cm wide marked line was attached to the test piece. % Stretched and held for 2 hours, then opened, allowed to stand for 30 minutes under each temperature condition, and then the length between the marked lines (l ₁ (cm)) was measured. %) Was calculated. The results are shown in Table 1.
Tensile elongation (%) = 100 × (l ₁ −2) / 2

Comparative Example 1
The same operation as in (1) and (2) in Example 1 was performed, and the block copolymer 1 was isolated by reprecipitation treatment with acetone. Using the obtained block copolymer 1, the same operation as (5) in Example 1 was performed, and the tensile permanent elongation (%) was calculated. The results are shown in Table 1.

Comparative Example 2
In Example 1, the operations of (1), (2) and (3) of Example 1 were similarly performed except that the same amount of styrene was used instead of p-methylstyrene. The number average molecular weight by GPC analysis of the hydrogenated polystyrene-poly (isoprene / butadiene) -polystyrene triblock copolymer obtained by the operation of (2) is 51000, and the styrene content measured by ¹ H-NMR The hydrogenation rates of the carbon-carbon double bonds based on the isoprene / butadiene units of the hydrogenated poly (isoprene / butadiene) block were 29% by mass and 99%, respectively. Further, when a part of the block copolymer (abbreviated as block copolymer (I) -2) obtained in (3) was sampled and subjected to GPC analysis, the block copolymer (I) The number average molecular weight of -2 was 51,000.
Using the obtained block copolymer (I) -2, the f value and tensile permanent elongation (%) were calculated in the same manner as in the operations of (4) and (5) in Example 1. The results are shown in Table 1.

Comparative Example 3
(1) In a pressure vessel equipped with a stirrer, 40 kg of cyclohexane and 250 ml of sec-butyllithium (11% by mass, cyclohexane solution) are added, 1.5 kg of styrene is added to this solution over 30 minutes, and polymerization is carried out at 50 ° C. for 30 minutes. Next, 7.0 kg of a mixture of isoprene and butadiene (isoprene / butadiene = 50/50; mass ratio) is added over 60 minutes and polymerized at 50 ° C. for 90 minutes, and 1.5 kg of styrene is added over 30 minutes. The reaction mixture containing polystyrene-poly (isoprene / butadiene) -polystyrene triblock copolymer was obtained by polymerizing at 50 ° C. for 30 minutes. When a part of the reaction mixture was sampled and subjected to GPC analysis, the polystyrene-poly (isoprene / butadiene) -polystyrene triblock copolymer contained in the reaction mixture had a number average molecular weight of 50,000, The styrene content measured by ¹ H-NMR was 30% by mass.

(2) 1.2 kg of tetrahydrofuran is added to the above reaction mixture at 50 ° C., and 1200 ml of tert-butyllithium (14 mass%, pentane solution) is kept in the mixture at a temperature of 40-60 ° C. After the addition, the mixture was stirred at the same temperature for 3 hours. This reaction mixture was poured into 10 kg of cyclohexane in which 0.18 kg of carbon dioxide was dissolved over 50 minutes at 50 ° C. and reacted at 60 ° C. for 1 hour.

(3) Next, the reaction mixture was diluted with 50 kg of cyclohexane, and separately prepared by adding 350 g of triisopropylaluminum (20 mass%, cyclohexane solution) to 60 g of nickel octylate (64 mass%, cyclohexane solution). And hydrogenation reaction was performed at 80 ° C. and a hydrogen pressure of 1 MPa for 5 hours, and 1.6 kg of a 10% by mass phosphoric acid aqueous solution was added. The block copolymer 2 was isolated by reprecipitating the organic phase containing the block copolymer 2 with 200 kg of acetone. A part of the resulting hydrogenated block copolymer (abbreviated as block copolymer 2) was sampled and subjected to GPC analysis. As a result, the number average molecular weight of the block copolymer 2 was 51,000. The hydrogenation rates of the carbon-carbon double bonds based on the styrene content measured by ¹ H-NMR and the isoprene / butadiene units of the hydrogenated poly (isoprene / butadiene) block were 29% by mass and 95%, respectively. It was.
Using the obtained block copolymer 2, the f value and tensile permanent elongation (%) were calculated in the same manner as in the operations of (4) and (5) in Example 1. The results are shown in Table 1.

  From the results shown in Table 1, the block copolymer (I) -1 obtained in Example 1 of the present invention is the block copolymer 1 obtained in Comparative Example 1 and the block obtained in Comparative Example 2. Compared to copolymer (I) -2, the f value is large, and the tensile permanent elongation at 70 ° C. is small. Therefore, it is understood that the polarity is high and the heat resistance is excellent. Further, the block copolymer 2 obtained in Comparative Example 3 has the same f value as that of the block copolymer (I) -1 obtained in Example 1, but the site where the carboxyl group is introduced is It is the α-position of the carbon-carbon double bond in the polymer block B, and is different in that a carboxyl group is introduced into the methyl group of the structural unit (a), that is, a carboxyl group is introduced into the polymer block A. . Due to the difference in the primary molecular structure, the tensile permanent elongation of the block copolymer (I) -1 obtained in Example 1 and particularly the tensile permanent elongation at 70 ° C. are the same as those obtained in Comparative Example 3. It can be seen that it is smaller than the combined 2 and excellent in heat resistance.

The block copolymer (I) obtained in the present invention can be effectively used as a polar resin modifier or the like by taking advantage of its polarity and heat resistance.

Claims (2)

A polymer mainly composed of a conjugated diene compound and at least one polymer block A mainly composed of an aromatic vinyl compound containing a structural unit (a) derived from methylstyrene having at least one methyl group bonded to a benzene ring. A hydrogenated block copolymer obtained by hydrogenating an aromatic vinyl compound block copolymer having at least one block B in the presence of a hydrogenation catalyst is allowed to act on an organic alkali metal compound in the presence of a base. A polar functional group is imparted by extracting a hydrogen atom of a methyl group on a benzene ring to form an anion, and then reacting the anionized hydrogenated block copolymer with a polar functional group imparting agent. Method for producing a hydrogenated block copolymer. A polymer mainly composed of a conjugated diene compound and at least one polymer block A mainly composed of an aromatic vinyl compound containing a structural unit (a) derived from methylstyrene having at least one methyl group bonded to a benzene ring. A hydrogenated block copolymer obtained by hydrogenating an aromatic vinyl compound block copolymer having at least one block B in the presence of a hydrogenation catalyst is allowed to act on an organic alkali metal compound in the presence of a base. A methyl group on the benzene ring is extracted to form an anion, and then the anionized hydrogenated block copolymer is reacted with a polar functional group-imparting agent to give a polar functional group. Hydrogenated block copolymer.