JPS61268710A - Branched random styrene-butadiene copolymer and composition thereof - Google Patents

Abstract

PURPOSE:To provide the titled copolymer having specific composition and thermal properties and excellent impact resilience, wet-skid resistance and abrasion resistance, by copolymerizing styrene and butadiene in the presence of a Lewis base and an organic Li compound, and adding a polyfunctional coupling agent to the copolymer. CONSTITUTION:Styrene is copolymerized with butadiene using an organic Li compound as a polymerization initiator in a hydrocarbon solvent containing a Lewis base, and the resultant copolymer is added and reacted with a polyfunctional coupling agent having >=3 reactive sites to obtain the objective copolymer characterized in that the Mooney viscosity (ML1+4, 100 deg.C) is 30-150, the ratio of the weight-average molecular weight MW to the number-average molecular weight MN (MW/MN) is 1.3-3.0, the vinyl bond content in the butadiene segment is 16-48%, the bonded styrene content is 10-45wt%, the amount of the chain consisting of single styrene unit is 65wt% of whole styrene units, the amount of the long styrene chain consisting of >=8 styrene units is <=5.0wt% of the whole styrene units, and the temperature difference between the deflection points in the glass transition temperature zone of an endothermic curve is >=15 deg.C measured by a differential scanning calorimeter (DSC).

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a copolymer chain in which the styrene units have a specific styrene chain distribution, a specific styrene composition distribution, and a specific styrene The present invention relates to a random styrene-butadiene copolymer having a styrene distribution and an excellent balance of impact resilience, skid resistance (slip resistance on wet road surfaces), and abrasion resistance, and a composition thereof.

[Conventional technology 1] Random styrene-butadiene copolymers have traditionally been widely used as rubber for tires, but in recent years, social demands for resource and energy conservation have led to demands for lower fuel consumption for automobiles and for safety when driving. In response to the recent demand for improved front wheel durability to cope with the increased load on the front wheels due to the shift to front-wheel drive vehicles, rubber for tires has been developed to improve fuel efficiency, high rebound resilience, and driving safety. In order to improve wet skid resistance and durability, excellent abrasion resistance is required.

However, 1. impact resilience and wet skid resistance are contradictory properties, and abrasion resistance and wet skid resistance are also contradictory properties, so in order to balance these contradictory properties, conventionally, different types of rubber were used. Blend compositions have been used. For example, blend compositions of styrene-butadiene copolymer rubber and polybutadiene, such as high-cis polybutadiene and low-cis polybutadiene, have been mainly used for passenger car tires. but.

These blend compositions have not yet achieved high levels of impact resilience, wave/skid resistance, and abrasion resistance.

Recently, various methods have been proposed aimed at improving impact resilience, wet skid resistance, and abrasion resistance by controlling the styrene distribution in the styrene-butadiene copolymer chains. A method of greatly increasing the styrene distribution width at the end of the chain (Japanese Patent Application Laid-Open No. 513-1
43209), a method for highly homogenizing styrene units in a copolymer chain (JP-A-57-100112, JP-A-57-179212, JP-A-59-140211)
, a method of blocking two types of copolymers with different styrene contents in the same copolymer chain (Japanese Patent Application Laid-open No. 57-16544
No. 5, JP-A No. 57-200413), and a method of specifying the styrene reaction composition distribution width and the peak temperature width of the glass transition point in a copolymer (JP-A No. 58-154711).

[Problems to be Solved by the Invention] However, although these copolymers show some improvement effects, they have not yet achieved high levels of impact resilience, wet skid resistance, and abrasion resistance.

The present invention was made in view of the above points, and an object of the present invention is to provide a branched random styrene-butadiene copolymer and a composition thereof that have an improved balance of impact resilience, wet skid resistance, and abrasion resistance. do.

[Means and effects for solving the problems] As a result of intensive studies on the chain distribution and compositional distribution of styrene units in a styrene-butadiene copolymer chain, the present invention has revealed that the styrene units in the copolymer chain are This was based on the discovery that a branched random styrene-butadiene copolymer having a styrene chain distribution and a specific styrene composition distribution has an excellent balance of impact resilience, wet skid resistance, and abrasion resistance. It is something that

That is, the present invention involves copolymerizing styrene and butadiene in a hydrocarbon solvent containing at least one type of Lewis base using an organolithium compound as a polymerization initiator to obtain a polyfunctional polymer having one and then at least three reactive sites. ; Mooney viscosity obtained by adding a pulling agent (MLI + 4,100
℃) is 30 to 150, weight average molecular weight (Wlw)
The ratio of Mw/MN to the number average molecular weight (MN) is 1.3
Ny 1,3.0, vinyl bond content of phthalene moiety 16% to 48%, bonded methane 10% to 45% by weight, branched component bonded by polyfunctional coupling agent 407% by weight The above styrene-butadiene copolymer has 65% by weight or more of fully bonded styrene in a single styrene chain consisting of one styrene monomer, and 5.0% by weight of fully bonded styrene in a long styrene chain consisting of 8 or more styrene monomers. % by weight or less, and differential scanning calorimeter (D
A raw material containing at least 30% by weight of a branched random styrene-butadiene copolymer, characterized in that the temperature difference between inflection points in the glass transition temperature region in an endothermic curve analyzed by SC) is 15°C or more The present invention relates to a rubber composition in which 5 to 60 parts by weight of rubber processing oil and 30 to 100 parts by weight of carbon black are blended with 100 parts by weight of the raw material rubber.

The branched random styrene-butadiene copolymer of the present invention and the rubber composition using the copolymer as a raw material rubber exhibit excellent properties and are used in various rubber applications, and are useful as tire tread applications.

The present invention will be explained in detail below.

Mooney viscosity of the copolymer of the present invention (ML1+4,100
℃) is 30 to 150. Preferably 5o to 100
It is. If the Mooney viscosity is less than 30, the effects of improving impact resilience and abrasion resistance will not be sufficient; if the Mooney viscosity exceeds 150, problems will remain in the processability of the compound, such as calendering processability and extrusion processability.

The ratio M8w/Ms of the weight average molecular weight (mw) to the number average molecular weight (MN) of the copolymer of the present invention is 1.3 to 3.
．． O1 is preferably 1.5 to 2.5.

When Mw /MN exceeds 3.0, workability is improved, but impact resilience is decreased, which is not preferable.
Styrene-butadiene copolymers obtained by emulsion polymerization generally have M
The copolymer of the present invention, which had ill/MN of 3.5 or more and was unsatisfactory in terms of impact resilience, is one that has improved the drawbacks of the above-mentioned copolymers.

The vinyl bond content of the butadiene moiety of the copolymer of the present invention is from 16% to 48%, preferably 16% or more and 35%
less than %. When the vinyl bond content is less than 16%, the wear resistance is improved, but the wet skid resistance decreases, which is undesirable.On the other hand, when the vinyl bond content is 48%
Exceeding this is undesirable because impact resilience and abrasion resistance decrease.

The bound styrene content of the copolymer of the present invention is 10% by weight to 4% by weight.
5% by weight, preferably 15% to 40% by weight. If the bound styrene content is less than 10% by weight, the wet skid resistance will decrease, which is undesirable. On the other hand, if the bound styrene content exceeds 45% by weight, the impact resilience and abrasion resistance will decrease, which is undesirable.

The branched component of the copolymer of the present invention is 40% by weight or more, preferably 50% by weight or more. If the zero-branched acid content is less than 40% by weight, the impact resilience is lowered and processability is also deteriorated, which is not preferable.

The styrene single chain having one styrene unit (hereinafter referred to as S1) of the copolymer of the present invention accounts for 65% by weight or more, preferably 75% by weight or more of the total bound styrene, and the styrene unit is 8
5. Fully bonded styrene (7) consisting of a long chain of styrene (hereinafter referred to as 88~). The amount of OTt must be less than or equal to 2.5% by weight, preferably less than 2.5% by weight. Wet skid resistance is unfavorable.

The temperature difference between the inflection points (hereinafter referred to as ΔT) in the glass transition temperature range of the copolymer of the present invention is 15°C or more, preferably 25°C.
℃ or higher, particularly preferably 30 to 70℃. ΔT is 1
Below 5°C, the styrene composition distribution width in the copolymer chain is small, resulting in wet skid resistance.

On the other hand, at temperatures above 15°C, the larger the ΔT, the wider the styrene composition distribution in the copolymer chain. Although the copolymer of the present invention satisfies a specific styrene chain distribution and has blendability, if ΔT becomes extremely large, the number of styrene single chains decreases, resulting in a decrease in impact resilience, which is undesirable. must satisfy 15 degrees or more. The temperature difference (ΔT) between the inflection points in the glass transition temperature range here refers to the differential scanning calorimeter (ns'c).
It is the temperature range from the first change point near the glass transition temperature to the final change point in the endothermic curve obtained by measurement using . The OSC measurement was carried out by the method shown in ASTM-03416-82.

FIG. 1 shows DSC endothermic curves of the styrene-butadiene copolymers obtained in Examples and Comparative Examples. As shown in Figure 1, the present invention includes a copolymer having two or more glass transition temperatures. A copolymer in which the copolymer is present in blocks has two glass transition temperatures and a relatively large ΔT, which has favorable properties.

The copolymer of the present invention is produced by the method described below. One method is to copolymerize styrene and butadiene with an organolithium compound in a hydrocarbon solvent containing at least one type of Lewis base, as described in JP-A No. 5111-1402.
As described in No. 11, butadiene is continuously supplied so that the styrene monomer content in the monomer composition ratio in the polymerization system falls within a specific concentration range, and a block copolymer having a certain monomer composition ratio is produced. A block copolymer or a butadiene polymer having a heptamer composition ratio different from that of the above-mentioned copolymer was obtained by the same polymerization method, and then a polyfunctional coupling agent was added to obtain the same copolymer. This is a method to obtain two types of random block copolymers with different monomer composition ratios in the chains. Another method is to copolymerize styrene and butadiene with an organolithium compound in a hydrocarbon solvent containing at least one type of Lewis base, so that the styrene monomer content in the 7-mer composition ratio in the polymerization system falls within a specific concentration range. Butadiene is continuously supplied to the polymerization system under specific conditions, and after the copolymerization is completed,
Branched random styrene is then prepared by adding a coupling agent having at least three reactive sites.
This is a method to obtain a butadiene copolymer. The styrene monomer content in the seven-mer composition ratio in the polymerization system is more than twice the amount of bound styrene in the final copolymer prepared from the total amount of styrene and a part of butadiene after the start of copolymerization, and 92% by weight or less, and after the start of copolymerization until the end of supplying the remaining butadiene, it must be lower than the above-mentioned styrene monomer content, and at the end of supplying the remaining butadiene, it needs to be below the bound styrene of the above-mentioned copolymer. It is preferable to start supplying the remaining butadiene simultaneously with the start of copolymerization.
It is necessary to terminate the supply after the polymerization conversion rate of the copolymer reaches 32% by weight. In addition, the remaining butadiene is
It is preferable to supply the styrene monomer so that the content of the styrene monomer in the seven-mer composition ratio in the polymerization system decreases as the copolymerization progresses.

The organolithium compound used in the present invention includes n-
Monoorganolithium compounds such as propyllithium, isopropyllithium, n-butyllithium, 5ec-butyllithium, tert-butyllithium, dilithiomethane, 1.4-dilithiobutane, 1.4-dilithio-2-
These include polyfunctional organolithium compounds such as ethylchloromethane, 1,2-dilithio-1,2-diphenylmethane, and 1.3.5-) lylithiobenzene, which may be used alone or in combination of two or more. used in a mixture of

Furthermore, as the polyfunctional organolithium compound used in the present invention, compounds that can be substantially converted into a polyfunctional organolithium compound by reacting the above-mentioned monoorganolithium compound with another compound are also used. For example, a reaction product of a monoorganolithium compound and a polyvinyl aromatic compound (Japanese Patent Publication No. 55-8652), a reaction product of a monoorganolithium compound and a conjugated diene, and/or a monovinyl aromatic compound, and then a polyvinyl aromatic compound or a reaction product obtained by simultaneously reacting a monoorganolithium compound, a conjugated diene, and/or a monovinyl aromatic compound, and the king of polyvinyl compounds (West German Patent No. 2003384).

As the hydrocarbon solvent used in the present invention, aliphatic, alicyclic, and aromatic hydrocarbons can be used. For example, the hydrocarbon solvent may include propane, isobutane,
Examples include n-hexane, isooctane, cyclopentane, cyclohexane, benzene, and toluene, and particularly preferred solvents are n-hexane, cyclohexane, and benzene. These may be used alone or as a mixture of two or more.

The Lewis base used in the present invention includes diethyl ether, ethylene glycol dimethyl ether,
Ethylene glycol di-n-butyl ether, ethylene glycol n-butyl-tert-butyl ether, ethylene glycol di-tert-butyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetrahydrofuran, α-methoxymethyltetrahydrofuran, dioxane, 1.2 Examples thereof include -dimethoxybenzene, triethylamine, N, N, N', N', -tetramethylethylenediamine, and botanical tert-amyl oxide. These compounds may be used alone or as a mixture of two or more.

The polyfunctional coupling agents used in the present invention include epoxidized soybean oil, epoxidized linseed oil, epoxidized liquid polybutadiene, dimethyl terephthalate, diethyl terephthalate, dimethyl phthalate, dimethyl isophthalate, diethyl adipate, Terephthalic acid dichloride, phthalic acid dichloride, isophthalic acid dichloride, adipic acid chloride, phthalic anhydride, maleic anhydride, silicon tetrachloride, methyltrichlorosilane, hexachlorosilane, tetramethoxycin, hydrogen tetrachloride, ferric chloride Examples include tin, methyltrichlorotin, stannic bromide, dodecyltrichlorotin, and the like. Among these, silicon tetrachloride and tin chloride are particularly preferred. When a copolymer coupled with stannic chloride is kneaded with carbon black, process oil, etc., the carbon gel increases, and its vulcanizate exhibits excellent impact resilience. Coupled copolymers show good processability, especially good extrusion properties. Therefore, if you want to obtain a copolymer with better processability, use silicon tetrachloride as a coupling agent. It is preferable to use it as

Although there are no particular limitations on the method of adding these polyfunctional coupling agents, the polyfunctional coupling agent is usually added after the copolymerization of styrene and butadiene is completed.

Alternatively, after the copolymerization is completed, a small amount of butadiene may be added, and then the polyfunctional coupling agent may be added.

The polymerization temperature in the present invention is in the range of 20 to 130°C. In the batch polymerization method, polymerization starts at 36-87°C,
It is recommended to perform at elevated temperature so that the maximum temperature reaches 30-125°C.

The copolymer of the present invention may be mixed with a process oil in a solution state, and after mixing, the solvent may be removed and used as an oil-extended rubber.

The copolymer of the present invention may be used alone or blended with other synthetic rubber or natural rubber, and used as a raw material rubber for various rubber applications, including 5 to 60 parts by weight of process oil and 230 parts by weight of process oil per 100 parts by weight of the copolymer. It can be used by blending up to 100 parts by weight. In this case, in order to exhibit the excellent properties of the present invention, at least 30% by weight of the raw rubber needs to be the copolymer of the present invention. Other preferred synthetic rubbers or natural rubbers to be used as a blend include emulsion polymerized styrene-butadiene copolymer, cis 1,4 polybutadiene, 1.2 syndiopolybutadiene, and 1.2 vinyl bond content of 10% to 90%. % of polybutadiene rubber, polyisoprene, or natural rubber, and one or more of these can be used.

Process oils used in rubber compounding consist of high-boiling components of petroleum fractions, and are usually classified into three types depending on the chemical structure of the oil's hydrocarbon molecules.The criteria for classification is viscosity specific gravity constant (
It depends on the size of VGC). General Ni VCC is 0.79
0 NO,849(7)Mo(7) is paraffin based, 0
．． Those with 650 to 0.899 are nandene-based, 0-900
The above are classified as aromatic.

Among these, since the copolymer of the present invention is used in combination with carbon black, aromatic type oils are generally used as process oils, and VGC0.930 is particularly preferable.
It is an aromatic type.

The amount of process oil used in the present invention is 10% of the copolymer.
The amount is 5 to 60 parts by weight, preferably 5 to 35 parts by weight relative to 0 parts by weight. If the process oil is less than 5 parts by weight, the dispersion of compounding agents such as carbon black and vulcanization accelerator will not be good, and if it exceeds 60 parts by weight, the physical properties of the obtained vulcanizate will be poor.

The carbon black used in the present invention is FEF,
HAF, 15AF, etc. are commonly used, and the amount used is 3 parts by weight per 100 parts by weight of the copolymer.
The amount is 0 to 100 parts by weight, preferably 40 to 75 parts by weight. If it is less than 30 parts by weight, the reinforcing effect will not be sufficient;
If it exceeds 0.00 parts by weight, impact resilience, breaking strength, etc. will decrease.

The copolymer of the present invention is the above carbon black.

In addition to rubber process oil, other reinforcing agents and fillers such as white carbon, calcium carbonate, and magnesium carbonate can also be blended, and zinc oxide, stearic acid, antioxidants, anti-ozonants, Vulcanization accelerators, vulcanizing agents, waxes, etc. can also be selected and blended as necessary.

Mixing of any of the above ingredients may be carried out by conventional means such as a Banbury, kneader or open roll.

After the rubber composition of the present invention thus obtained is subjected to a vulcanization process, it can be used in many useful applications, such as tire applications such as tire treads, carcass, and sidewalls, extruded products, automobile window frames, industrial products, etc. It can be used for the following purposes.

[Example 1] Hereinafter, the present invention will be explained with reference to Examples, but these Examples are not intended to limit the present invention.

Note that measurements of various characteristics were carried out using the following methods.

The styrene chain distribution of styrene-butadiene copolymer is
Analyzed using a method recently developed by Kuninaka et al. Specifically, the styrene chain distribution is analyzed by gel permeation chromatogram (GPC) of a decomposed product obtained by ozone cleavage of all the double bonds of butadiene units (Proceedings of the Society of Polymer Science and Technology, Vol. 29, No. 8). Section 2055).

Temperature difference (Δ
T) is OSC (product name: 5S) manufactured by Seiko Electronics Co., Ltd.
It was determined by the temperature range from the first change point near the glass transition temperature to the final change point in the endothermic curve obtained by measurement using 0560). Measurement conditions are ASTM-0341
The ratio Mw/MW of zero weight average molecular weight (M-) to number average molecular weight (WiN) according to 6-82 is G
The weight average molecular weight (Mll) and number average molecular weight (MW) in terms of polystyrene were calculated from the GPC curve obtained using PC (trade name: 204 compact type) and tetrahydrofuran as the mobile phase. The styrene monomer content and polymerization rate in the 7-mer group were determined by analyzing the sample extracted from the polymerization vessel using Shimadzu's gas chromatography (product name: GC?A). Calculated using the ratio.

Mooney viscosity is 1 using the L rotor in the usual way.
Measured at 00°C. The bound styrene was calculated from the absorption based on phenyl groups at 282 nm using ultraviolet absorption spectroscopy. The microstructure of the butadiene moiety was calculated by the Hampton method using an infrared spectrophotometer. The hardness, tensile strength, 300% modulus, and elongation of the vulcanizate are JIS K.
Measured by 8301. Repulsion resilience was measured using a Dunlop trypsometer at a test temperature of 70°C.

Abrasion resistance was measured using a Pico abrasion tester. Wet skid resistance was measured using British Road Research Institute equipment.

Example 1. Comparative Example 1.2 Under a nitrogen atmosphere, predetermined amounts of cyclohexane, tetrahydrofuran, and styrene (hereinafter referred to as primary styrene) as shown in Table 1 were placed in a stainless steel polymerization vessel with an internal volume of about 10 cm and equipped with a stirrer. .3-Butadiene (hereinafter referred to as primary butadiene) was charged, and the temperature of the mixture in the polymerization vessel was adjusted to about 74° C. while stirring the mixture vigorously. Next, after starting copolymerization by adding a predetermined amount of n-butyllithium, 1,3-butadiene (hereinafter referred to as additionally added primary butadiene) was continuously added to the polymerization system using a metering pump, as shown in Table 1. The supply started at a constant rate. Additional addition 1st
After the supply of butadiene was finished and the copolymerization was completed when one polymerization unit reached the maximum temperature, a predetermined amount of stannic chloride was added and the reaction was allowed to proceed for about 10 minutes. To the thus obtained copolymer solution, 5 g of 2,6-tert-butyl-4-methylphenol was added as a stabilizer, and the solvent was removed by heating to obtain a copolymer.

However, in Comparative Example 2, 1.2-butadiene was 0.1? The styrene monomer content in the monomer composition in the 6-polymerization system in which g was added to the polymerization system was always less than about 86% by weight, and was about 16% by weight at the end of the first butadiene addition. Moreover, the polymerization conversion rate at the end of the supply was about 65% by weight. The polymerization conditions and basic properties of the obtained copolymer are shown in Tables 1 and 3.

The temperature difference between the inflection points in the glass transition temperature range and the DSC endothermic curve of the copolymer obtained in Example 1 are shown as (a) in FIG. An unvulcanized rubber composition obtained by cross-mixing in a small pressure kneader according to the formulation shown in Table 2 was vulcanized at 145° C., and physical properties were evaluated. The measurement results are shown in Table 3.

Example 2 A method similar to Example 1, except that the primary butadiene was added to 0.
38 kg, and the additionally added primary butadiene was changed to 0.30 kg, and the supply of additionally added primary butadiene was started when the polymerization conversion rate of the finally obtained copolymer reached approximately 50% by weight. Copolymerization was carried out under the polymerization conditions shown in Table 1 by changing the feed rate of the additional primary butadiene to 0.0375 kg/min. Table 11 Table 3 shows the polymerization conditions, basic properties, and vulcanizate properties of the obtained copolymer.
Shown below.

Example 3.4 Into the polymerization vessel used in Example 1, predetermined amounts of cyclohexane, tetrahydrofuran, primary styrene, and
The primary butadiene was charged, and the temperature of the mixture in the polymerization vessel was adjusted to about 73°C while stirring the mixture vigorously.
Next, after copolymerization was started by adding a predetermined amount of n-butyllithium, a predetermined amount of additionally added primary butadiene was started to be continuously supplied to the polymerization system at a constant rate using a metering pump. After finishing the supply of the additional primary butadiene and completing the copolymerization,
Predetermined amount of styrene (hereinafter referred to as secondary styrene), 1
．． 3-butadiene (hereinafter referred to as secondary butadiene) is added, and then a predetermined amount of 1,3-butadiene (hereinafter additionally added secondary butadiene, referred to as ene) is continuously added to the polymerization system at a constant rate using a metering pump. It was supplied by After the supply of the additionally added stannic butadiene was completed and the copolymerization was completed, a predetermined amount of stannic chloride was added and the reaction was allowed to proceed for about 10 minutes. 2,6-sheet tert-
5 g of butyl-4-methylphenol was added and the solvent was removed by heating to obtain a branched random block copolymer. However, in Example 4, the secondary styrene and the additional secondary butadiene were not added, and the entire amount of styrene was added to the polymerization vessel before adding n-butyllithium. Table 11 shows the polymerization conditions, basic properties, and vulcanizate properties of the obtained copolymer.
The temperature difference between the inflection points in the glass transition temperature range and the SC endothermic curve of the copolymer obtained in Example 4 shown in Table 3 are shown as (b) in FIG. 1.

Comparative Example 3 In the same manner as in Example 3, but without additional addition of primary and secondary butadiene, and with potassium ter
0.058 g of t-butyl alkoxide (KTB) was newly added to the polymerization system, and copolymerization was carried out under the polymerization conditions shown in Table 1 to obtain a monobranched random block copolymer. The polymerization conditions, basic properties, and vulcanizate properties of the obtained copolymer are shown in Tables 1 and 3.

Comparative Example 4 The same method as in Example 1 was used, except that the primary butadiene was added to 0.
38 kg, the additional primary butadiene was changed to 0.30 kg, and the additional primary butadiene was added at a time when the polymerization conversion rate of the finally obtained copolymer reached about 15% by weight. Copolymerization was carried out under the polymerization conditions shown in Table 1 by changing the feed rate of the added primary butadiene to 0.042 kg for 7 minutes.

The polymerization conditions, basic properties, and vulcanizate properties of the obtained copolymer are shown in Tables 1 and 3, and the temperature difference between the inflection points in the glass transition temperature range and the DSC endothermic curve are shown in Figure 1. Shown as (c).

Comparative Example 5 Into the polymerization vessel used in Example 1, predetermined amounts of cyclohexane, tetrahydrofuran, styrene, 1,
After 3-butadiene was charged and the mixture in the polymerization vessel was vigorously stirred and the temperature of this mixture was adjusted to about 73°C, a predetermined amount of n-butyllithium was added to start copolymerization. As a stabilizer to the thus obtained copolymer solution after reaching the maximum temperature and finishing the copolymerization.

5 g of di-tert-butyl-4-methylphenol was added and the solvent was removed under heating to obtain a copolymer. Table 11 shows the polymerization conditions, basic properties, and vulcanizate properties of the obtained copolymer.
It is shown in Table-3.

As can be seen from Table 1, Examples 1 to 4 have impact resilience,
Excellent balance of wet skid resistance and abrasion resistance.

Examples 5-9. Comparative Examples 6 to 9 Copolymerization was carried out in the same manner as in Example 1, except that stannic chloride was changed to tetrachlorosilane and under the polymerization conditions shown in Table 4 to obtain Te copolymers. In the polymerization systems of the various copolymers mentioned above, the styrene monomer content in the Kazummer composition ratio in each polymerization system is lower than the styrene monomer content before the start of polymerization during the addition of primary butadiene, and when the supply ends, the styrene monomer content is lower than the styrene monomer content before the start of polymerization. The amount of bound styrene in the copolymer obtained was less than that of the copolymer obtained. Furthermore, the polymerization conversion rate at the end of the additional first butadiene supply was 82% by weight. The polymerization conditions, basic properties, and vulcanizate properties of the copolymer obtained in the above manner are shown in Tables 4 and 5.

As can be seen from Table 5, Examples 5 to 9 have an excellent balance of impact resilience, wet skid resistance, and abrasion resistance. On the other hand, Comparative Examples 6 and 8 have excellent impact resilience and abrasion resistance, but are inferior in wet skid resistance. Comparative example 7.
9 has excellent wet skid properties, but has good abrasion resistance.

[Effect of the invention] The branched random styrene-butadiene copolymer according to the present invention has a specific styrene chain unit in the copolymer chain and a specific styrene composition distribution, so that the branched random styrene-butadiene copolymer has a specific styrene chain unit and a specific styrene composition distribution. Rubber compositions containing polymers and their copolymers have an excellent balance of impact resilience, wet skit resistance, and abrasion resistance, and are useful for tire applications such as tire treads, carcass, and sidewalls, as well as extruded products, automobile window frames, It can be used for many purposes such as industrial supplies and has great industrial significance.

[Brief explanation of drawings]

Figure 1 shows the endothermic curves measured by DSC of the copolymers obtained in each example and comparative example. In Figure 1, ΔT indicates the temperature difference between the inflection points in the glass transition temperature range, and ( b) is Example 1
, (b) shows the SC endothermic curve of the copolymer obtained in Example 4, and (c) shows the SC endothermic curve of the copolymer obtained in Comparative Example 4. Applicant Hiki Elastomer Co., Ltd. Agent Yutaka 1) Good dissolution 1 figure 1 person 1 degree ('C,) Procedural amendment April 10, 1986 Mr. Michibe Uga, Commissioner of the Patent Office, Incident Indication of Japanese Patent Application No. 60-4108 2, Name of the invention Branched random styrene-butadiene copolymer and its composition 3, Relationship with the amended person case Patent applicant: 1-chome, Yurakucho, Chiyoda-ku, Tokyo No. 2 Nippon Elastomer Co., Ltd. - Representative Director and President Takao Yokoyama 4, Representative Room 204, Sanshin Building, 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Telephone 501-2138 Toyota Naigai Patent Office (8) Ibid. Page 12 ``Random Block Kyodo 5'' on line 12, ``Detailed Description of the Invention'' column 6 of the specification subject to amendment, Contents of the amendment (1) ``Styrene composition'' on page 3, lines 14 to 15 of the specification. distribution and a specific styrene styrene distribution”
``Styrene composition distribution''. (2) In the second line of page 4 of the same book, ``Used ekita ga'' is corrected to ``Used ekita ga''. (3) On page 4, lines 4 to 5 of the circular, "Requirements for low fuel consumption of automobiles and requirements for safety when driving" have been changed to "Requirements for low fuel consumption for automobiles and improvement of safety when driving. 'request'. (4) Circular, page 7, lines 15 to 16 r: At least a branched random styrene-butadiene copolymer characterized by a temperature of 15°C or higher, instead of ``at least a branched random styrene-butadiene copolymer characterized by a temperature of 15°C or higher. The branched random styrene-butadiene copolymer and the copolymer are corrected to "at least". (5) On page 12, line 7 of the same book, "obtain a block copolymer" is corrected to "obtain a block copolymer." (12) In the first line of page 22 of the same book, "monomer addition rate" is corrected to "obtain a branched random styrene-butadiene copolymer having a random block copolymer." (7) "Remaining butadiene copolymerization starts" on page 13, line 10 of the same book is corrected to "remaining butadiene starts copolymerization." (8) “l,4-dilithio-2-
"Ethylclohexane" is corrected to "1,4-dilithio-2-ethylcyclohexane". (8) In the same book, page 15, line 8, “by mixture of two or more types” was changed to “
"A mixture of two or more species." (10) "Adipate chloride" on page 16, line 10 of the same book is corrected to "adipate dichloride." (11) In the fourth line from the bottom of page 21 of the circular, "Styrene monomer content and polymerization conversion rate in the monomer set in the polymerization system" was changed to "Styrene monomer content and polymerization conversion rate in the monomer composition in the polymerization system." I am corrected. Correct it to "monomer conversion rate." (13) Insert "The branched component was determined from the area ratio of the GPC chart" after "Calculated using." in the second line of page 22 of the same book. (14) "Remove the solvent by heating" on page 25, line 15 of the same book is corrected to "remove the four solvents by heating." (15) On page 27, line 13 of the same book, ``After the copolymerization is completed,'' is corrected to ``After the copolymerization is completed, a predetermined amount of stannic chloride is added and reacted for about 10 minutes.'' (16) "Remove the solvent by heating" in the sixth line from the bottom of page 27 of the circular is corrected to "remove the solvent by heating." (17) "Table-1" in the third line from the bottom of page 27 of the circular is corrected to "r-Table-3." (16) "First styrene" in the seventh line from the bottom of the first column on the left in Table 1, page 28 of the circular, is corrected to "second styrene." (16) "Styrene monomer content" on page 31, line 8 of the same book is corrected to "styrene monomer content." (20) “92% by weight” on page 31, line 11 of the same book was changed to “8
2% by weight or more.” (21) In the bottom line of page 31 of the same book, replace “wear-resistant” with “
"It has poor wear resistance." (22) On page 34, line 13 of the same book, ``Figure 1 is the endothermic curve of the copolymer obtained in each example and comparative example according to the DSCIl!III constant.'' This is the endothermic curve measured by DSC of the copolymer obtained in the example.'' Procedural amendment Written June 16, 1986 Michibe Uga, Commissioner of the Patent Office1, Indication of the case, Japanese Patent Application No. 60-41082, Title of the invention: Branched random styrene-butadiene copolymer and composition thereof 3. Person making the amendment Relationship with the case Patent applicant: 1-1-2 Yurakucho, Chiyoda-ku, Tokyo President and CEO of Japan Elastomer Co., Ltd. Takao Yokoyama 4; Agent: 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Sanshin Building, Room 204 Telephone: 501-21365, Subject of Amendment Procedures as shown in Column 6 of ``Subject of Amendment'' of the Written Procedural Amendment submitted on April 10, 1981, and the contents of the amendment in the appendix. 10th, Michibe Uga, Commissioner of the Patent Office 1. 13 indications Patent Application No. 60-4108 2, title of the invention 3, relationship with the person making the amendment case Patent applicant: 1-chome Yurakucho, Chiyoda-ku, Tokyo No. 2 Hiki Elastomer Co., Ltd. President and Representative Director Takao Yokoyama 4, Agent Room 204, Sanshin Building, 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Phone: 501-21365o "Explanation" column and "Brief explanation of drawing" column

Claims (1)

[Claims] 1. Styrene and butadiene are copolymerized using an organolithium compound as a polymerization initiator in a hydrocarbon solvent containing at least one type of Lewis base, and then a polymer having at least three reactive sites is copolymerized. Mooney viscosity (ML_1_+_4, 100°C) obtained by adding a functional coupling agent is 3
0 to 150, the ratio of weight average molecular weight (@M@W) to number average molecular weight (@M@N) @M@W/@M@N is 1.3
to 3.0, the vinyl bond content of the butadiene moiety is 16
% to 48%, bound styrene 10% to 45% by weight
A styrene-butadiene copolymer containing 40% by weight or more of branched components bonded by a polyfunctional coupling agent, in which the single styrene chain consisting of one styrene monomer is 65% by weight of the total bonded styrene. % or more, long styrene chains consisting of 8 or more styrene monomers account for 5.0% by weight or less of the total bonded styrene, and differential scanning calorimetry (DS
A branched random styrene-butadiene copolymer characterized in that the temperature difference between inflection points in the glass transition temperature region in the endothermic curve analyzed by C) is 15°C or more. 2. Copolymerizing styrene and butadiene in a hydrocarbon solvent containing at least one type of Lewis base using an organolithium compound as a polymerization initiator, and then copolymerizing a polyfunctional coupling agent having at least three reactive sites. The Mooney viscosity (ML_1_+_4, 100℃) obtained by adding is 3
0 to 150, the ratio of weight average molecular weight (@M@W) to number average molecular weight (@M@N) @M@W/@M@N is 1.3
to 3.0, vinyl bond content in butadiene moiety 16%
A styrene-butadiene copolymer containing 48% to 48% of bound styrene, 10% to 45% by weight of bound styrene, and 40% by weight or more of branched components bonded by a polyfunctional coupling agent, the styrene-butadiene copolymer having one styrene monomer. The total styrene single chain is 65% by weight or more, and the styrene monomer is 8% by weight.
5. Fully bonded styrene is a long chain of styrene.
0% by weight or less, and the temperature difference between the inflection points in the glass transition temperature region of the endothermic curve analyzed by differential scanning calorimetry (DSC) is 15°C or more. 10% of the raw material rubber containing at least 30% by weight of styrene-butadiene copolymer.
A rubber composition containing 5 to 60 parts by weight of rubber processing oil and 30 to 100 parts by weight of carbon black.