JP2687215B2 - Styrene-butadiene copolymer and composition thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a styrene-butadiene copolymer widely used as a rubber for tires of automobiles and the like, and a composition containing the styrene-butadiene copolymer. Is. [Prior Art] In recent years, as an automobile tire, due to various energy situations and speeding up of automobiles, safety is achieved when driving on a paved open road, that is, improvement of braking performance and fuel saving, and unpaved roads. It is required to prevent cracks and chipping from occurring in large tires of trucks, large buses, etc. when driving on a rough road. From these things, as a rubber for tires, improvement of impact resilience as fuel saving, improvement of wet skid resistance for improvement of braking performance, and strength and elongation energy for prevention of cracking and chipping, that is, improvement of tensile strength, And the improvement of three types of physical properties is required. Conventionally, a blend composition of a styrene-butadiene copolymer and a different rubber or a resin has been used as a rubber for tires, and improvement has been studied by controlling the distribution of styrene in the styrene-butadiene copolymer chain. . For example, in JP-A-56-143209 and JP-A-60-8310, a method of greatly increasing the styrene concentration at the end of the copolymer chain, and JP-A-56-61413 and JP-A- Sho 5
7-165445 and JP-A-57-200413 disclose methods for blocking two kinds of copolymers having different styrene contents in the same copolymer chain, and the impact resilience and the wet skid resistance are disclosed by the respective methods. Sexuality is being improved. On the other hand, JP-B-45-18671 discloses that a styrene-butadiene copolymer having a specific amount of styrene block has excellent dynamic properties and cold flow prevention, which is a non-coupling compound. Is a polymer,
Not enough in impact resilience, wet skid resistance and tensile strength. [Problems to be Solved by the Invention] Impact resilience and wet skid resistance are contradictory properties, and a tire rubber excellent in both these properties at the same time is obtained by improving a styrene-butadiene copolymer. However, a rubber which maintains both of these properties and is excellent in tensile strength has not been obtained yet. [Means and Actions for Solving Problems] The present inventors diligently studied the styrene composition distribution in the styrene-butadiene copolymer chain, and as a result, surprisingly, a specific molecular weight in the copolymer chain was obtained. A styrene-butadiene copolymer containing a specific amount of a styrene block having a is excellent in tensile strength without impairing high impact resilience and high wet skid resistance, and a rubber containing the copolymer. The present invention has been found out that a rubber composition using as a raw material rubber exhibits excellent performance as a rubber for tires. Hereinafter, the present invention will be described in detail. The content of the styrene block (hereinafter abbreviated as styrene block) in which 8 or more styrene monomer units are connected in the styrene-butadiene copolymer of the present invention is 5 to 15% by weight. If the styrene block content is less than 5% by weight, the tensile strength is insufficient, and if it exceeds 15% by weight, the impact resilience is reduced, which is not preferable. The molecular weight of the styrene block of the styrene-butadiene copolymer of the present invention measured by gem permeation chromatography (hereinafter abbreviated as GPC) is 3,000 to 1
It is 5,000, preferably 4,000 to 12,000. If the molecular weight of the styrene block is less than 3,000, the tensile strength is insufficient, and if it exceeds 15,000, the impact resilience is greatly reduced. The molecular weight and content of the styrene block in the styrene-butadiene copolymer chain here are measured by the method developed by Tanaka et al. This method uses double bonds of butadiene units in the styrene-butadiene copolymer chain to
All of them measure GPC of decomposition products obtained by ozone cleavage. (Proceedings of the Society of Polymer Science, Vol. 29, No. 7, p. 2055, 1980
(Year) The styrene block molecular weight is a molecular weight converted by a polystyrene standard substance of a main peak of GPC of a styrene long chain portion in which eight or more styrene monomer units in which the ozonolysis product is connected are eight or more in sequence. Further, the content of the styrene block is a portion in which eight or more styrene monomer units of the ozone decomposition product are connected, and this is calculated by the following formula. The position of the styrene block occupied in the styrene-butadiene copolymer chain of the present invention may be located in any part of the copolymer chain, but it is preferably the end part of the copolymer chain, particularly the free end. It is preferably located at. Further, two or more styrene blocks may be contained in the copolymer chain, and in this case, the styrene blocks may have different molecular weights. The styrene-butadiene copolymer of the present invention has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 35 to 150, preferably 40 to 90.
It is. When the Mooney viscosity is less than 35, impact resilience and tensile strength are insufficient, and when it exceeds 150, problems remain in the processability such as calendering processability and extrusion processability of the composition. The styrene-butadiene copolymer of the present invention is coupled with a coupling agent, and the Mooney viscosity before the coupling is preferably 30-80. If the Mooney viscosity before coupling is less than 30, the tensile strength will decrease,
If it exceeds 80, workability is deteriorated, which is not preferable. The bound styrene content of the styrene-butadiene copolymer of the present invention is 10 to 45% by weight, preferably 15 to 40% by weight. If the content of bound styrene is less than 10% by weight, wet skid resistance and tensile strength are lowered, and if it exceeds 45% by weight, impact resilience is lowered, which is not preferable. The vinyl bond content of the butadiene part of the styrene-butadiene copolymer of the present invention is 13 to 50%, and particularly preferably
16-30%. If the vinyl bond content is less than 13%, the wet skid property is deteriorated, and if it exceeds 50%, the impact resilience and the tensile strength are deteriorated. The distribution of 1,2-vinyl groups in the copolymer chain is uniform even in the copolymer chain.
The distribution may be such that it gradually decreases along the copolymer chain as shown in JP-A-5, or it may be distributed in blocks (USP-3301840). The styrene-butadiene copolymer of the present invention may have a functional group such as an amino group or a hydroxyl group or an organic metal introduced at the chain end of the copolymer. The styrene-butadiene copolymer of the present invention is blended, kneaded, with carbon black, process oil, and other compounding agents,
The vulcanized composition has excellent impact resilience, wet skid resistance, and tensile strength. Hereinafter, the method for producing the styrene-butadiene copolymer of the present invention will be described. First, in one method, a styrene-butadiene copolymer was obtained by copolymerizing styrene and 1,3-butadiene using an organic lithium compound as a polymerization initiator in a hydrocarbon solvent containing at least one Lewis base. After that, or when the common use of styrene and 1,3-butadiene was started, or after that, 1,3-butadiene was continuously added so that the styrene monomer content in the monomer composition ratio in the polymerization system was within a specific concentration range. Of the styrene-butadiene copolymer, after the styrene-butadiene copolymer was added and reacted to obtain a styrene-butadiene copolymer containing a specific styrene block at the chain end of the copolymer, Then, a coupling agent is added for coupling. Another method is to polymerize styrene using an organolithium compound as a polymerization initiator in a hydrocarbon solvent containing at least one Lewis base, and then copolymerize styrene with 1.3-butadiene, or Obtained by continuously supplying and copolymerizing 1,3-butadiene so that the styrene monomer content in the monomer composition ratio in the polymerization system falls within a specific concentration range after or simultaneously with the copolymerization of 3-butadiene. A styrene-butadiene polymer containing a specific styrene block at the head end position in the copolymer chain is obtained, and then a coupling agent is added for coupling. In addition, a styrene monomer is further added to the styrene-butadiene copolymer before the coupling reaction for polymerization, and then a coupling agent is added for coupling so that two or more specific styrene monomers are present in the copolymer chain. There is also a method of obtaining a styrene-butadiene copolymer containing a styrene block. Further, as another method, during the reaction of various styrene-butadiene copolymer and the coupling agent obtained by the above method, an organic compound capable of introducing an amino group or a hydroxyl group,
There is also a method of obtaining a coupled styrene-butadiene copolymer having a specific styrene block by adding one or more organic metal compounds and / or reacting them. The amount of organolithium used as a polymerization initiator of the styrene-butadiene copolymer of the present invention is 0.2 to 7.0 mmol as metallic lithium per 100 g of the monomer, preferably 0.4 mmo.
at l. Organic lithium compounds include n-propyl lithium, isopropyl lithium, n-butyl lithium, se
Monoorganolithium compounds such as c-butyllithium and tert-butyllithium, dilithiomethane, 1,4-dilithioptan, 1,4-dilithio-2-ethylcyclohexane, 1,2
Examples thereof include polyfunctional organolithium compounds such as -dilithio-1,2-diphenylmethane and 1,3,5-trilithiobenzene, which are used alone or as a mixture of two or more kinds. As the polyfunctional organolithium compound, a compound which can be substantially a polyfunctional organolithium compound by reacting the above monoorganolithium compound with another compound is also used. For example, a reaction product of a monoorganolithium compound and a polyvinyl aromatic compound (Japanese Patent Publication No. Sho 55-6652).
Gazette), a reaction product obtained by simultaneously reacting a monoorganolithium compound with a conjugated diene, and / or a monovinylaromatic compound, and a polyvinyl compound (West German Patent
2003384, JP-A-57-40513) and the like. As the hydrocarbon solvent used in the present invention, aliphatic, alicyclic, and aromatic hydrocarbons can be used. For example, the hydrocarbon solvent is propane, isobutane, n-hexane, isooctane, cyclopentane, cyclohexane, benzene, toluene and the like, and particularly preferred solvents are n-hexane, cyclohesane and benzene. These are used as one kind or as a mixture of two or more kinds. As the Lewis base used in the present invention, diethyl ether, ethylene glycol dimethyl ether,
Ethylene glycol di-n-butyl ether, ethylene glycol n-butyl tert-butyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetrahydrofuran,
α-methoxybenzene, triethylamine, N, N, N ′,
N'-tetramethylethylenediamine, potassium-ter
t-amyl oxide and the like. These compounds are 1
It is used as a species or a mixture of two or more species. Examples of the polyfunctional coupling agent used in the present invention include epoxidized liquid polybutadiene, epoxidized linseed oil, epoxidized soybean oil, dimethyl terephthalate, dimethyl phthalate, dimethyl terephthalate, dimethyl isophthalate, diethyl adipate, and terephthalate. Acid dichloride, phthalic dichloride, isophthalic dichloride, adipic chloride, phthalic anhydride, maleic anhydride, stannous chloride, dichloromethylsilane, dibutyltin dichloride, divinylbenzene, silicon tetrachloride, methyltrichlorosilane, Hexachlorosilane, tetramethoxysilane, carbon tetrachloride, stannic chloride, methyltrichlorotin, stannic bromide, triphenyltin chloride, triphenylgermanium chloride, triphenyllead chloride and the like. Particularly preferred is stannic chloride, the copolymer coupled with stannic chloride being carbon black,
When kneaded with process oil etc., carbon gel increases,
The vulcanizate also exhibits excellent impact resilience. The method of adding these polyfunctional coupling agents is not particularly limited, but usually, after the completion of the polymerization of styrene and 1,3-butadiene, or at the end of the polymerization, a small amount of 1,3
Add the polyfunctional coupling agent after adding and reacting with butadiene. The amount of coupling agent to be added is usually determined by comparison with the amount of active lithium, but is preferably 0.001 to 1 mol per 1 mol of active lithium. When a functional group such as an amino group or a hydroxyl group, or an organic metal or the like is introduced into the copolymer of the present invention, the organic compound used as a modifier is a C═Y group (Y represents an oxygen atom or a sulfur atom) in the molecule. ) And an NR ₁ group (R ₁ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group or an aryl group), respectively, and is, for example, 4,4′- Bis (dimethylamino) benzophenone, 4,4'-bis (dimethylamino) thiobenzophenone, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone,
1,3-dipropyl-2-imidazolidinone, 1-methyl-3 (2-methoxyethyl) -2-imidazolidinone,
1-Methyl-3- (2-ethoxyethyl) -2-imidazolidinone, 1,3-di- (2-ethoxyethyl) -2-
Imidazolidinone, 1,3-dimethylethylenethiourea, N, N'-diethylpropyleneurea, N-methyl-
N'-ethylpropylene urea, 1,3-dimethyl-3,4,
5,6-Tetrahydro-2 (1H) -pyrimidinone, N-methylacridone, tetramethylurea, tetramethylthiourea, N, N-diphenylacetamide, N, N-dimethylbenzamide, N, N-dimethylacetamide, 1, 1,3,3
-Tetrabutylurea, N, N'-carbonyldiimidazole, N-methyl-2-pyrrolidone, N-methyl-ε-
Examples thereof include caprolactam, succinimide, N-methylsuccinimide, and methyl carbamate. Alternatively, the general formula R ₂
N = C = Y) Isocyanates represented by _n (Y in the formula:
Represents an oxygen atom or a sulfur atom, R ₂ represents an aliphatic group, a cycloaliphatic group, an aromatic group, or a hydrocarbon group having 1 to 20 carbon atoms, and n represents an integer of 1,2,3). , For example, methyl isocyanate, ethyl isocyanate, isocyanic acid-n-butyl, phenyl isocyanate, isocyanic acid-1-naphthyl, methyl isothiocyanate, ethyl isothiocyanate, isothiocyanate-isobutyl, isothiocyanate-n-butyl, isothiocyanate. -Tert-butyl, allyl isothiocyanate, phenyl isothiocyanate, benzyl isothiocyanate, isothiocyanate-
p-tolyl, diphenyl ether-4,4'-diisocyanate, lysine diisocyanate, 4,4'-diphenylmethane diisocyanate, toluene diisocyanate,
Hexamethylene diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, benzene-1,2,4-triisocyanate and the like can be mentioned. Also,
General formula as the organometallic compound (R ₃₎ 3 organometallic compound represented by _-M-X (wherein R ₃ is alkyl group having 1 to 20 carbon atoms, represents an alkoxyalkyl group, M is the Periodic Table IV
Represents a metal atom of group a, and X represents a halogen atom)
And, for example, trimethylchlorosilane, triethoxychlorosilane, triethylgermanium chloride, trimethyltin chloride, triethyltin chloride, tri-n-butyltin chloride, tri-n-butyltin bromide, tripropyltin chloride, butyldimethyltin iodide. , Di-n-butylvinyltin chloride, n-
Butyldicyclohexyl tin bromide, tri-n-butyl lead chloride and the like can be mentioned. The method of adding these modifiers is not particularly limited, but they may be added after the completion of the copolymerization of styrene and butadiene, simultaneously with the coupling agent, before the coupling reaction, or after the coupling reaction. Although the amount of the modifier used is not particularly limited, it is usually determined by the ratio of the amount of active lithium and / or the coupling agent, or according to the purpose. The styrene-butadiene copolymer of the present invention may be polymerized by either a batch polymerization method or a continuous polymerization method. The polymerization temperature may be in the range of 20 to 130 ° C, but in the case of batch polymerization, the maximum temperature is 36 to 87 ° C and the maximum temperature is 90 to 125 ° C.
It is preferable to carry out at an elevated temperature so that the temperature becomes ° C. After completion of the prescribed reaction, an antioxidant such as 2,6-di-tert-butyl-p-cresol is added, and the resulting polymer is subjected to usual post-treatments such as separation, washing and drying to obtain the desired copolymer. To get The styrene-butadiene copolymer of the present invention may be used as an oil-extended rubber by mixing it with a process oil in a solution state, removing the solvent after mixing. Next, the rubber composition containing the styrene-butadiene copolymer, which is another invention of the present invention, will be described in detail. The rubber composition of the present invention is a composition of a raw material rubber containing the styrene-butadiene copolymer of the present invention, a process oil, carbon black, and other compounding agents. The styrene-butadiene copolymer of the present invention contained in the raw material rubber of the rubber composition of the present invention is at least 30% by weight or more, and when the amount is less than 30% by weight, the copolymer has high impact resilience and high Excellent properties such as wet skid resistance and high tensile strength are not expressed. The other rubber blended with the raw material rubber may be a synthetic rubber or a natural rubber, preferably a styrene-butadiene copolymer, cis-1,4-polybutadiene, 1,2-
Syndiopolybutadiene, 1,2-vinyl bond content 10-9
It is 0% polybutadiene rubber, polyisoprene, or natural rubber, and one or more of these can be used. The amount of the process oil used in the rubber composition of the present invention is 5 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the raw rubber. If the process oil is less than 5 parts by weight, the dispersion of carbon black and other compounding agents will decrease,
If it exceeds 100 parts by weight, the physical properties of the finally obtained vulcanizate will be poor. Process oils used for rubber compounding consist of high boiling point components of petroleum fractions and are usually classified into three types according to the chemical structure of hydrocarbon molecules. The classification standard depends on the size of the viscosity specific gravity constant (hereinafter abbreviated as VGC). VGC is generally 0.790 to 0.8
49 are classified as paraffinic, 0.850 to 0.899 as naphthenic, and 0.900 or more as aromatic. Since the process oil blended in the rubber composition of the present invention contains carbon black, an aromatic oil is generally used, and a process oil having VGC of 0.930 or more is preferable. The amount of carbon black used in the rubber composition of the present invention is 30 to 150 parts by weight, preferably 40 to 75 parts by weight, based on 100 parts by weight of the raw rubber. If the amount of carbon black is less than 30 parts by weight, the reinforcing effect is not sufficient, and if it exceeds 150 parts by weight, physical properties such as impact resilience and breaking strength deteriorate. As the carbon black, those commonly used such as FEF, HAF, ISAF may be blended. In the rubber composition of the present invention, a compounding agent may be added in addition to the raw material rubber, the process oil, and the carbon black. As the compounding agent, white carbon, calcium carbonate, a reinforcing agent such as magnesium carbonate, a filler, zinc oxide, Stearic acid, antioxidants, antiozonants, vulcanization accelerators, vulcanizing agents, waxes, etc. can be selected and compounded as necessary. The rubber composition of the present invention is obtained by blending and kneading the above-mentioned raw material rubber, process oil and the like by a usual means such as Banbury, kneader or open roll. The rubber composition is used for various purposes after undergoing a vulcanization step. [Examples] The present invention is described below with reference to examples, but these examples do not limit the present invention. Incidentally, the measurement of various characteristics in the examples of the present invention was carried out by the following methods. The content of styrene block in the styrene-butadiene copolymer chain and the molecular weight of the styrene block were measured by GPC, which was developed by Tanaka et al. This was compared with GPC as a polystyrene standard substance, and the styrene block content in which 8 or more styrene monomer units were connected was determined from the GPC chart of the copolymer decomposition product. Similarly, the styrene block molecular weight was determined by comparing the molecular weight at the GPC peak position of the styrene block in which eight or more styrene monomer units of the above-mentioned decomposed product were connected to the molecular weight of the polystyrene standard substance. The bound styrene content was calculated from the absorption based on the phenyl group at 262 nm by the ultraviolet absorption spectrum method. The Mooney viscosity is measured by using the L rotor in the usual way.
It was measured at 100 ° C. and 2 rpm. The microstructure of the butadiene part was measured using an infrared spectrophotometer and calculated by the Hampton method. The tensile strength of the vulcanized product was measured according to JIS-K6301. Further, the impact resilience of the vulcanized product was measured at a test temperature of 70 ° C using a Dunlop trypsometer. Wet skid resistance was measured using a skid resistance device manufactured by British Road Research Institute. The copolymers of Examples 1 to 7 and Comparative Examples 1 to 8 shown in Table 2 were all made of stainless steel with an internal volume of about 10 in a nitrogen atmosphere, and the predetermined amount of raw materials shown in Table 1 was used in a stirrer-equipped polymerizer. Prepared by stirring reaction at elevated temperature, and after completion of the reaction, 2,6 as a stabilizer
5 g of -di-tert-butyl-p-cresol were added and the solvent was removed by heating. Table 2 shows these basic characteristics,
The unvulcanized rubber composition obtained by kneading and mixing these copolymers in a small pressure kneader according to the formulation of Table 3 was used.
Vulcanized at 5 ° C. The results of evaluating the physical properties of these vulcanizates are shown in Table 4 and FIGS. 1 and 2. The polymerization method of each copolymer will be described below. Example 1, Comparative Example 8 A predetermined amount of cyclohexane, tetrahydrofuran and a predetermined amount of styrene were charged into a polymerization vessel, the temperature was adjusted while stirring, and then n-butyllithium was added to initiate polymerization. After completion of styrene polymerization, the styrenes shown in Table 1
A mixture of 1,3-butadiene was added to initiate the copolymerization.
Then, 3 minutes after the start of the copolymerization, the continuous additional supply of 1,3-butadiene was started. In Example 1, until 13 minutes after the start of the copolymerization, in Comparative Example 8, until 15 minutes after the start of the copolymerization. Copolymerization was carried out while continuously supplying 1,3-butadiene. After the completion of the copolymerization, a predetermined amount of stannic chloride was added to each to terminate the reaction. Examples 2 and 3 Charge a predetermined amount of cyclohexane, tetrahydrofuran and styrene into a polymerization vessel, adjust the temperature while stirring,
Thereafter, n-butyllithium was added to polymerize styrene. After the completion of styrene polymerization, a mixture of styrene and 1,3-butadiene shown in Table 1 was added to carry out copolymerization. After completion of the copolymerization, a predetermined amount of stannic chloride was added to terminate the reaction. Examples 4 and 5 Predetermined amounts of cyclohexane, tetrahydrofuran and styrene were charged in a polymerization vessel, the temperature was adjusted while stirring, and then n-butyllithium was added to initiate polymerization. After completion of styrene polymerization, styrene and 1,
A mixture of 3-butadiene was added to initiate the copolymerization. Next, under the conditions shown in Table 1, 1,3-butadiene was continuously added and copolymerized. After completion of the copolymerization, a predetermined amount of stannic chloride was added and reacted, and in Example 5, further N-methyl-
2-Pyrrolidone was added to terminate the reaction. Examples 6,7 Divinylbenzene 2.6 g, 1,3 in cyclohexane beforehand
A predetermined amount of a reaction product obtained by reacting 24 g of butadiene with 6.4 g of n-butyllithium was used as a polymerization initiator. The polymerization procedure of Example 6 is the same as that of Example 3, and the raw material thereof and the conditions for continuous addition of 1,3 butadiene are shown in Table 1. In Example 7, styrene was polymerized after the completion of the first copolymerization under the conditions shown in Table 1. After the completion of each polymerization, a predetermined amount of triphenyltin chloride was added to terminate the reaction. Comparative Examples 1, 2, 4, 6 Polymerization was carried out in the same manner as in Example 1 using the raw materials shown in Table 1. Comparative Example 3 Using the same initiators as in Examples 6 and 7, all the raw materials shown in Table 1 were first charged into a polymerization vessel to carry out polymerization, and after completion of the polymerization, triphenyltin chloride was added to terminate the reaction. Comparative Example 5 Polymerization was carried out under the conditions shown in Table 1 in the same manner as in Example 2, and after the completion of the polymerization, a predetermined amount of stannic chloride was added to terminate the reaction. Comparative Example 7 Polymerization was carried out in the same manner as in Example 1, except that the coupling agent was not added and about 0.5 g of methanol was added to terminate the reaction. Fig. 1 shows the results of tensile strength and impact resilience from Table 4, and Fig. 2 shows the results of impact resilience and wet skid resistance. As can be seen from these, Examples 1 to 7 show tensile strength. , And the impact resilience and wet skid resistance are all excellent and there is no particularly inferior performance, but Comparative Examples 1 to 8 are inferior in any of the three types of performance. That is, Comparative Example 1 has tensile strength and wet skid resistance, Comparative Examples 3, 6 and 7 have tensile strength, Comparative Examples 2, 4 and 5 have impact resilience, and Comparative Example 8
However, the balance between impact resilience and tensile strength is inferior to other performances. [Effects of the Invention] The styrene-butadiene copolymer of the present invention is excellent in impact resilience, wet skid resistance, and tensile strength. Therefore, the rubber composition of the present invention using the copolymer is a tire tread. It exhibits excellent performance for tires such as carcass and sidewalls, and can be applied to other applications such as extruded products, automobile window frames, anti-vibration rubber, and industrial products, and its industrial significance is great.

[Brief description of the drawings] 1 and 2 are drawings showing the results of the examples.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area (C08L 9/06 57:02)

Claims (1)

(57) [Claims] Styrene obtained by copolymerizing styrene and 1,3-butadiene by using an organic lithium compound as a polymerization initiator in a hydrocarbon solvent containing at least one Lewis base, and then reacting with a polyfunctional coupling agent. It is a butadiene copolymer, and the bound styrene content of the copolymer is
10 to 45% by weight, the styrene monomer unit of the copolymer is 8
Styrene block content of 5 to 15% by weight
The styrene block has a molecular weight of 3,000 to 15,00 as measured by gel permeation chromatography.
0, the vinyl bond content of the butadiene portion of the copolymer is 13
~ 50%, the Mooney viscosity of the copolymer (ML _{1 + 4} , 100 ℃) is 3
A styrene-butadiene copolymer that is 5 to 150. 2. Styrene obtained by copolymerizing styrene and 1,3-butadiene by using an organic lithium compound as a polymerization initiator in a hydrocarbon solvent containing at least one Lewis base, and then reacting with a polyfunctional coupling agent. It is a butadiene copolymer, and the bound styrene content of the copolymer is
10 to 45% by weight, the styrene monomer unit of the copolymer is 8
Styrene block content of 5 to 15% by weight
The styrene block has a molecular weight of 3,000 to 15,00 as measured by gel permeation chromatography.
0, the vinyl bond content of the butadiene portion of the copolymer is 13
-50%, Mooney viscosity (ML _{1 + 4} , 100 ° C) of styrene-butadiene copolymer having a viscosity of 35-150 at least 30% by weight, and 100 parts by weight of the raw rubber, 5 parts by weight of the process oil 5 for rubber.
A rubber composition containing 100 to 100 parts by weight and 30 to 150 parts by weight of carbon black.