JPS62127330A - Rubber composition for tire tread - Google Patents

Abstract

PURPOSE:To obtain the titled rubber composition excellent in tensile strength, resiliency, heat build-up, etc., by adding carbon black, sulfur, a vulcanization accelerator, etc., to a stock rubber containing a specified living polymer having C=S bonds in the molecule. CONSTITUTION:Styrene is copolymerized with butadiene in a hydrocarbon solvent in the presence of an organolithium catalyst (e.g., ethyllithium) to prepare a living polymer having a vinyl bond content in the butadiene part of 10-70% and a MW distribution (Mw/Mn) of 1.2-3. This living polymer is reacted with carbon disulfide, a xanthogen compound, a dithio acid compound (e.g., methyl dithioacetate) or the like to introduce C=S bonds into the molecule. 10-100pts. wt. carbon black, 0.3-5pts.wt. sulfur and a vulcanization accelerator are added to 100pts.wt. stock rubber containing at least 10wt% above obtained polymer of a Mooney viscosity of 20-150.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a styrene-butadiene copolymer composition prepared using an organolithium catalyst, which is suitable for the tread of the fuel-efficient tie A7.

[Conventional technology]

In recent years, due to the soaring price of crude oil, energy conservation has been advocated in various industries, including automobiles.
Many attempts have been made to reduce gasoline consumption.
The engine has been improved, the weight of the car body and tires has been reduced, and the air resistance of the car body and the rolling resistance of the tie A7 have been reduced.

In an attempt to save energy related to these automobiles,
Various attempts have been made to reduce the rolling resistance of tie V for automobiles, such as improving the structure of the tire and improving the vulcanized rubber used in the tread of tie A7.

In an attempt to reduce the rolling resistance of these ties V, a method of improving the vulcanized rubber, that is, reducing the energy loss of the vulcanized rubber to improve rebound resilience or heat generation f1
Methods to improve this include improving the raw rubber used for H0 sulfur rubber, changing the type of Rikiichi pump rack, and reducing the amount of carbon black or A-il used in H0 sulfur rubber to achieve high repulsion. How to make it elastic has been tested.

Among the above improvement methods, the method for improving the raw T4 rubber is to use a polymer with a higher molecular weight than before, based on the previous method of improving the raw T4 rubber. As a result, the impact resilience can be improved, but the Mooney viscosity of Rubber J3 and the compound increases, and the elasticity decreases, so a significant improvement cannot be achieved. On the other hand, when changing the blending recipe to reduce the blending rate of A-il and carbon black, the Mooney viscosity of the blend increases, and in this case, the processability of J3 becomes worse. It is difficult to improve without sacrificing sex.

By the way, it has recently been found that a random styrene-butadiene copolymer rubber with many vinyl bonds and a branched structure is suitable for use in wetsuit applications, and rubbers with various structures have been studied and various proposals have been made. There is. For example, when a soubrene-butadiene co-synthesized rubber with an increased content of styrene is tin-coupled with a branched styrene-butadiene co-synthesized rubber, a butadiene compound is added immediately before the coupling reaction to cause polymerization. A method for improving rolling resistance has been proposed (Japanese Patent Application Laid-Open No. 57-87407.
JP-A-58-16260! l). However, even with this method, the improvement in rolling resistance is still not sufficient, and there are problems such as the manufacturing method becoming complicated.

In addition, a complete polymer produced by continuously introducing a t-sumer into a polymerization zone with high stirring efficiency controlled at a temperature of 80°C or higher using a catalyst consisting of an organolithium compound and a Lewis base and regressing the polymerization. Random styrene-butadiene copolymer rubber has been proposed (Japanese Patent Laid-Open No. 57-10
0112). This polymer showed excellent performance in terms of tensile strength, impact resilience, low heat build-up, abrasion resistance, and wet skid properties.

However, there was a need for further improvement in terms of rebound resilience, low heat build-up, etc.

In addition, as a method for improving raw rubber, a method of introducing a functional group at the end of a living polymer has been proposed.For example, a method of producing a living polymer using a difunctional anionic initiator has been proposed. After that, there is a method in which active groups are introduced at both ends of the molecule by the action of a prominent sulfenyl chloride (Japanese Patent Publication No. 44-855). However, this method has a high molecular weight and cannot yield a polymer with living potassium ends at both ends. There were problems with its use in T leaves, as it was difficult to handle and the organic sulnoenyl chloride was difficult to handle, and the obtained polymers were insufficient in terms of tensile strength, modulus, etc. Furthermore, amino groups were introduced at the terminals. Is there a way to do it?
4, 4? Jm]1lTh 60-137913. 17
nlln 60-137914>Repulsion,;! Improvements in II properties, low heat generation properties, abrasion resistance, wet skid properties, etc. were insufficient.

[Problems to be Solved by the Invention] Therefore, the inventors of the present invention have developed a method that does not impair wet/skid properties, workability, etc., has tensile strength, rebound resilience, low heat generation, and wear resistance. As a result of extensive research in order to develop a styrene-butadiene copolymer rubber composition with extremely excellent performance, a specific styrene-butadiene copolymer rubber composition was invented.

(Means and effects for solving the problem) Specifically, the present invention copolymerizes styrene and butadiene in a hydrocarbon solvent using an organolithium catalyst, and the amount of bound styrene is 5.
~45% by weight, vinyl bond of butadiene moiety is 1O-7
0%, the molecular seedling molecule R (Mw
/Mn) of 1.2 to 3 is reacted with carbon disulfide, a quilintogun compound, and a dithioic acid compound to introduce a C=S bond into the molecule, and the Mooney viscosity is 20.
- 100 parts by weight of raw 11 rubber containing at least 10% by weight of a polymer of
This is a rubber composition suitable for tie A7 tread, containing ~100 parts by weight, 0.3 to 5 parts by weight of sulfur, and a vulcanization accelerator.

The present invention will be described in detail below.

The organolithium catalyst used in the present invention is a hydrocarbon having at least one lydium atom bonded thereto, such as T-butyl lidium, pyrulybrum, n-butyl lidium cum, 5ec-butyl lithium, t
ert-butyllithium, phenyllithium, cum, propenyllithium, hexyllithium, 1,4-ziridy,;
Examples include 1-n-butane, and particularly preferred are n-butyllithium cum and 5ec-butyllithium cum.These organolithium catalysts can be used not only as one type but also as a mixture of two or more types.

The amount of the lithium catalyst used depends on the Mooney viscosity of the produced polymer, but is usually 0.3 to 100'J per 100'J of monomer.
3 millimoles, preferably 0.5 to 1.5 millimoles.

The hydrocarbon solvent used in the present invention is tan-
Butane, n~pentane, 1so-pentane, r)-hexane, n-hebutane, 1so-octane, cyclohexane, medylcyclobentane, bemvin, toluene, etc., and a particularly preferred solvent is n-hexane. , n-hebutane, and cyclohekiline.

This hydrocarbon solvent may be used alone, or two or more kinds may be used.
! It may be used in conjunction with ilj T, which is usually
1 to 20 parts of skewers are used per 1 part of the body.

The bonded styrene index of the soubrene-butadiene copolymer rubber of the present invention is 5.~45! ! ! It is early%. If it is less than 5% by weight, the tensile strength of the vulcanized rubber will be poor, and if it exceeds 45% by weight, heat will increase and performance will deteriorate. A particularly preferable range is 10
~35,000 m%.

The vinyl bond in the butadiene moiety of the styrene-butadiene copolymer rubber of the present invention is 10 to 70%, preferably 15 to 5%.
It is 0%. Low vinyl bonding results in low wet skid resistance, while high vinyl bonding results in low abrasion resistance. Particularly preferred is a range of 20 to 40%.

The molecular weight distribution of the styrene-butadiene copolymer rubber of the present invention was determined using GPC using a calibration curve of iL boristyrene, and the weight average molecular weight (MW) and number average molecular weight (
The size of the molecular weight distribution expressed as the ratio of Mn) MW/M
n) is 1.2 to 3, preferably 1.5 to 2.5. If the molecular M distribution is small, the processability will be poor, and if the molecular weight distribution is large, the impact resilience and low heat generation properties will be poor. Further, the molecule R and the molecule B obtained by GPC may have one or two peaks. A coupling agent such as silicon tetrachloride, alkyl silicon trichloride, dialkyl silicon dichloride, or tin tetrachloride, which is usually used to improve processability, is used to form a linear or branched coupling polymer. A method may also be used.

The styrene-butadiene copolymer rubber of the present invention is preferably a random copolymer. The styrene chain distribution of the styrene-butadiene copolymer rubber is analyzed by GPC of a low-temperature ozonolyzed product of the copolymer rubber. This method was developed by Yamanaka et al. In this method, the styrene chain molecule 5 covers the double viscosity of butadiene and is cleaved by ozone, and the decomposed product 17 is analyzed by GPC () lacromole.
cules, 1983.16°1925). In the copolymer rubber of the present invention, isolated styrene analyzed by this method, that is, styrene having a chain of 1 styrene unit, preferably accounts for 40 ffl m% or more, more preferably 50% by weight or more, of the total bonded styrene, and has long chains. block styrene,
That is, the amount of styrene having a chain of 8 or more styrene units is preferably 5% by weight or less, more preferably 2.5% by weight or less of the total combined styrene. Even if the isolated styrene content is less than 40Φm% or the long chain block styrene content is more than 5% by weight, the copolymer rubber of the present invention has the following excellent properties: 1) high impact resilience, low heat generation, and high The balance of wet skid resistance is unfavorable.

The reactive compounds to be reacted with the styrene-butadiene copolymer pasting polymer of the present invention include carbon disulfide,
It is a xanthogen compound and a dithi-1 compound. Here, the xanthogen compounds include luxanthogenic acid, ethylxanthogenic acid, n-propylkyrindovonic acid, isopropylxanthogenic acid, n-butylxanthogenic acid,
Furkylxanthogenic acids such as ec-butylxanthogenic acid, n-hexylkylintogonic acid, n-octylxanthic acid, phenylkylintogonic acid, p-tolyl-
Allylkylintogunic acid of 1 lintogenic acid and lithium, nium, potassium salts of these 4 phosphoric acids and dimedylkylintogun disulfide, diethylkylintogun disulfide, di-n-70 pylxanthogen disulfide, diisopropyl-kylintogun disulfide, di-n-abreu) non-togun disulfide, di-5ec-butyl chilintogun disulfide,
G[1-he2-silnitrintogundisulfide,
=t-lintogen disulfides such as diphenylkylintogun disulfide and di-p-tolyl-lintogun disulfide are preferably used. Among these, particularly preferred are Kirin 1 to Gen disulfides such as dimethylkyrintogun disulfide, diisopropyl 4-1 nontogun disulfide, di-n-hexylxanthogen disulfide, and diphenylkylintogun disulfide. Examples of dithi-AK compounds include compounds having the general formula R-C-3-, such as dithioformic acid, sibu, 71M acid, ethancal small dibu-71[1, isobutanecarbodibu-AW, isopentanecarpodiIA acid, etc. Carbodiyl AK and their lithium, 1-lium, and potassium salts, as well as thioacyl sulfite and dibutyl chloride derived from these, methyl dithiolate, dithiochloride dithiolate, Nisful dithiamonoate such as butyl acid is preferably used.

Preferred among these 1) are dithia 1M earth esters such as dithi Δ mebble, dithioethyl ethyl acetate, and ethane rufodib 71M zobl.

These compounds, for living polymer 17,
It is fed at a rate of 0.3-10-El, preferably 0.5-5 tl. More preferably, the proportion is 1 to 3 moles. Feed ♀ acts only as a coupling agent for a small amount of the porous polymer, resulting in an abnormal increase in viscosity and a decrease in IJ processability. On the other hand, if the feed ω is too large, unreacted substances may cause the generation of odor and shorten the vulcanization ratio of +1:'1, which is not preferable. The reaction between living polymers and these compounds is extremely rapid, and the reaction temperature is 1. E( is generally a reaction time of room temperature to 120' C1 and several seconds to several hours.

A living polymer is reacted with these compounds to introduce a C=S bond into the molecule, and an antioxidant is usually added to the polymer, if necessary, it is oil-extended, and the solvent is removed by a conventional method.

The Mooney viscosity of the styrene-butadiene copolymer rubber in which a C=S bond is introduced into the molecule used in the present invention is as follows. If the Mooney viscosity is lower than this, the tensile strength, abrasion resistance, rebound resilience, and low heat build-up of the vulcanized rubber will be inferior; Sometimes excessive torque is applied or the carbon is poorly dispersed, resulting in poor performance of the vulcanized rubber.

The styrene-butadiene co-neutralized rubber in which a C=S bond is introduced into the molecule used in the present invention is used alone or blended with other synthetic rubber or natural rubber to form a raw material rubber. In this case, in order to exhibit the excellent properties of the present invention, at least 10% by weight of the raw material rubber must be the styrene-butadiene copolymer rubber in which C=S bonds are introduced into the molecules of the present invention. do.

It is preferably 30 fold π% or more.

Other synthetic rubbers or natural rubbers that can be blended include emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber containing less than 35% 1,2 vinyl, cis-1,4 polybutadiene rubber, 1.
Examples include 2-syndiopolybutadiene rubber, 10 to 90% 1,2 vinyl polybutadiene rubber, synthetic polyisoprene rubber, and natural rubber, and one or more of these can be used.

The carbon black cloth used in the present invention contains 10 to 100 parts of carbon black per 100 parts by weight of raw rubber.
Used for heavy foot parts. If it is less than 10 parts by weight, the tensile strength and resistance to 1
? The wear resistance is not sufficient, and on the other hand, if the amount exceeds 100 parts by weight, the rubber elasticity will be significantly reduced, which is not preferable. Preferably it is 20 to 80 suspended parts.

The carbon black classes used in the present invention are:
Preferably, iodine absorption shield ♀ (I A > 60 mg/U or more and dibuburnotare-1 oil absorption (DBP) Bou
T! Carphone black of y'100!7 or more is used. Such carbon black is a carphone black with a small particle size and a high-speed steel 1 to Rakuji A. 15 may not be possible. Preferably, the IA is 80 mg/g or more and the DBP is 100 m/g.
100g or more of carbon black.

These carbon blacks include, for example, IIAF,
There are those called 15AF and SAF.

In the present invention, 0.3 to 5 parts by weight of sulfur is used as a vulcanizing agent per 100 parts by weight of raw rubber.

If sulfur is too low, tensile strength, impact resilience, and abrasion resistance will be insufficient, and if it is too high, rubber elasticity will be reduced. Preferably 0.5
~2.5 monographs.

In the present invention, various conventionally known vulcanization accelerators can be used as the vulcanization accelerator, but deazole vulcanization accelerators are preferably used.

1” [1 is a sulfur accelerator. These JKI sulfur auxiliary agents have excellent tensile strength, repulsion bullets, [(l, chu[
f wear ↑ (1 is (-7), but proper vulcanization may not be obtained with other accelerators. These accelerators include:
Preferably, vulcanization accelerator M (2-mercaptobenzothiazole), vulcanization accelerator DM (dibenzodialyldilylphide), vulcanization accelerator C7 (N-cyclohexyl-2-pensibacylsulfonamide) ).

The vulcanization accelerator used is 0.2 to 3 parts per 100 parts of rubber.
Parts by weight are preferred.

In the composition of the present invention, resin, which is commonly used as a wrestling oil for rubber compounding, is used depending on the purpose and use. They are divided into paraffinic, naphthenic, and aromatic based on their chemical structure.Aromatic types are used for applications that emphasize tensile strength and abrasion resistance, while naphthenic and even paraffinic systems are used for applications that emphasize impact resilience and low-temperature properties. is preferably used. The amount is 10 raw rubber
It is preferable to use 5 to 100 parts by weight with respect to 0 parts by weight, and if it is less than 5 parts by weight, the processability will be poor and the dispersion of carbon black will be poor, so performance such as tensile strength and elongation will not be exhibited. If it exceeds 1 part by weight, the tensile strength, impact resilience, and hardness will significantly decrease, which is undesirable.

The 1% polymerized rubber composition of the present invention may further contain other fillers other than carbon black, if necessary, when used.
It is possible to add zinc oxide, stearic acid, antioxidants, antiozonants, wax, etc.

In addition, fillers other than carbon black include silicic acid,
Silicates, calcium carbonate, titanium oxide, various clays, etc. are used.

The copolymer rubber composition of the present invention is obtained by kneading the above-mentioned components using a mixer known for use in the rubber industry, such as an oven roll, an internal mixer, etc., by various known methods (7). The rubber products obtained through the vulcanization process exhibit superior performance compared to rubber products made from conventionally known rubber compositions.

Among them, it exhibits especially high impact resilience, low heat build-up, tensile strength, and wet skid property. Therefore, it can be used in applications where ordinary styrene-butadiene copolymer rubber compositions are used,
In particular, it is suitably used for tie V treads.

(Examples) The present invention will be specifically explained with reference to some examples below, but the present invention is not limited to these examples. "Parts" means "parts by weight" unless otherwise specified.

Example 1 A reactor with an internal volume of 1 month made of stainless steel and a di-V-ket was connected in two base rows, and 1,3-butadiene and styrene (75/25 weight ratio) were used as monomers. n as a solvent
- to: V″l, n-butyl as a catalyst) Ch’7
Unevenness 1fu (A 100!J'r') 0.06 g
(7) In PI synthesis (1)tn), 0.60 phm of ethylene glycoyl dibutyl-[-thyl] was used as the vinylating agent.
Continuous copolymerization was carried out using 0.03 mol of 1°2-butadiene per mol of catalyst as an allene compound. In the first reactor, the internal temperature was controlled to be 100° C., and the monomer was supplied using a metering pump so that the average fliQA time was 45 minutes. The polymerization rate at the outlet of the first unit was measured by gas chromatography, and it was 17, indicating a butadiene polymerization rate of 97% and a styrene polymerization rate of 95%. Mooney viscosity 100℃ 1M was measured with a Mooney viscometer, ML 41 was 1
Doo 4 17.

Furthermore, the polymer solution was continuously introduced into the second reactor, and 0.143 t) of carbon disulfide was continuously added to the second reactor, and the internal temperature was controlled to be 100°C.

After adding 2,6-ditarchelybutyl-p-cresol as an antioxidant at the exit of the second station, the solvent is removed by steam stripping and dried with a hot roll at 110°C to form C=S in the molecule. 19 is a styrene-butadiene copolymer rubber with a bond introduced. This is referred to as evaluation sample A.

Measure the Mooney viscosity of the crushed rubber using a Mooney viscometer at 100°.
Measured by C, ML 83 is 19. Also, the bonding step 1
+4 The 1,2-vinyl trifluoride of the allene and butadiene moieties was measured by the Hump I~N method using an infrared spectrophotometer 54, and the bound styrene was 25% by weight, and the 1°2-vinyl moiety of the butadiene moiety was 29. % is 19. Molecular weight Ili1. 4 using a standard borisdyrene polymer calibration curve using tGPc.
The result was Mw/Mn: 2.4. Further, the GPC curve showed that the molecular weight distribution was one peak. Also,
Isolated styrene determined by GPC of the ozonolyzed product was 65% by weight of the total styrene, and long-chain blocked styrene was 0.8% by weight.

Next, using evaluation sample A as raw rubber, (IA): 90 m
FI/g, (DBP): 119d/100g of N
Using 339 carbon black and the formulation shown in Table 1, the content fi1.7J! Blends were obtained, vulcanized, and their physical properties were measured using a test Banbury Millimeter according to the standard blending procedure of ASTM-D-3403-75. The measurements were carried out according to the following method.

(1)&J! Tensile strength: JIS-K-630
I followed 1.

(2) Impact resilience: Lubke method according to JIS-6301. However, impact resilience at 70°C
Leave it in the open air at 0℃ for 1 hour, then quickly take it out and measure.

(3) Using a Guttu Lidge heating Guttu Lich Flexmeter, load 48 pounds, displacement 0.225 inch, start 50℃, rotation speed 1
The test was conducted under the condition of 800 ppm, and the upper back temperature difference after 20 minutes was expressed.

(4) Wet skid resistance Swunley London Portable Skid Destruction
Safedy Walk (manufactured by 3M) is used as the road surface.
was measured according to the method of ASTM-E-808-74. It was expressed as an index with the measured value of 3B R1502 set as 100.

The famous Til is shown in Table 3.

Examples 2 to 5, Comparative Examples 1 to 2 The rubber for evaluation was produced in the same manner as in Example 1, except that the method shown in Table 2 was used. The rubber thus obtained is referred to as evaluation samples B-G. Table 3 using evaluation samples B to G
EXAMPLE 17 Compounds were vulcanized in the same manner as in Example 1, except that the method shown in Example 1 was carried out, and each physical property was measured.

Each physical property is shown in Table 3.

Example 6 As carbon black (IA): 44ffiff/
9, (DBP): 114d/10 (IJ's N 5
Compound No. 17 was vulcanized in the same manner as in Example 1, except that 50 carbon black was used, and the various physical properties were measured.

Each physical property is shown in Table 3.

Examples 7-8, Comparative Example 3 The same method as in Example 1 was carried out, except that the rubbers shown in Table 3 were blended and used as the rubber component.

Each physical property is shown in Table 3.

Comparative Example 4 Using 5BR1502 as a raw rubber, compound 19 was vulcanized in the same manner as in Example 1, and its physical properties were measured. Each physical property is shown in Table 3.

Table 1 Blend No.0 Carbon black 50 Parts by weight Stearic acid 2 Parts by weight Hon 1 Kyodo Oil
X-140 12N-cyclohexyl-2-benzothiazylsulfenamide vulcanization strip I: 160°C x 20 minutes (blank below) From the results shown in Table 3, the rubber of the present invention was determined as follows. The characteristics of the composition are clear.

Examples 1 to 6 are all compositions of the present invention in which a polymer having a C═S group introduced into the molecule was used as a rubber component.

From the comparison between Example 1 and Comparative Example 1, it was found that the composition of the present invention has c.
Compared to a composition using a polymer without =sm, tensile strength, impact resilience, and heat generation are all greatly improved.

Comparative Example 2 is a composition using polybutadiene into which a C-8 group has been introduced as a rubber component, and the tensile strength is significantly inferior to that of Example 1.

Example 6 uses a polymer into which a C=S group has been introduced as the rubber component and N550 carbon black as the carbon black, and is significantly superior to Comparative Example 1 in impact resilience and heat generation properties.

Examples 7 and 8 are both compositions in which a polymer with c-8 groups introduced into the molecule was used as part of the rubber component, while comparative example 3 similarly used a polymer without c-8 groups. Regarding the compositions, Examples 7 and 8 are superior to Comparative Example 3 in terms of tensile strength, impact resilience, and heat generation.

Example 9 In a reactor with internal volume ION, equipped with a stirrer and a di(·kerato), 4200 g of cyclohexine and 85 g of purified butadiene were added.
After charging 0g of purified styrene, 150g of purified styrene, and 40g of detrahydrofuran as a polar compound, and maintaining the temperature at 60°C, 0.6'J of n-butylridyl cum was added as a catalyst to start polymerization. Φ combined temperature 60~90
The polymerization reaction was carried out for 40 minutes while maintaining the temperature at °C. First, 0.244 Cl of tin tetrachloride (
Adding this product ratio 0.4) to n-butylridium,
Subsequently, 3.049 diisopropylkyrin 1-gen disulfide was immediately added to initiate the coupling reaction and C=S
This was followed by a combined introduction.

Further, 10 g of sheet tert-bubblyhydroxytoluene was added as an antioxidant to this combined solution, and the solvent was evaporated to recover the polymer.

(77 polymer (Test 1rEI A > Mooney viscosity)" structure has 34% of 1.4-trans bonds, 1
The content was 22% for 4-cis bonds and 44% for 1,2-vinyl bonds.

Mw/Mn from molecular ffi and molecular GPC: 1.
66 Te, and the GPC curve showed that there were two peaks for each molecular weight.

The Mooney viscosity of the polymer before coupling is 1
3, and Mw/Mn was 1.10.

Furthermore, the amount of isolated soubrene determined by GPC of the ozone decomposed product was 55% by weight based on the total styrene, and the amount of long chain blocked styrene was 3.8% by weight.

Next, using this polymer as a raw material rubber, a compound No. 19 was vulcanized using N339 carbon black according to the formulation shown in Table 1 in the same manner as in Example 1, and each physical property was measured.

The measurement results are shown in Table 4.

Comparative Example 5 Added diisopropyl xanthogen disulfide 710
55 were carried out in the same manner as in Example 9, except that L was not used.

In the same manner as in Example 9, the 1-[1-sulfur properties were measured. The measurement results are shown in Table 4.

Example 9 is a rubber composition of the present invention, and compared to Comparative Example 5, tensile strength, impact resilience, and heat generation are significantly improved.

(Effect of the invention) As mentioned above, the rubber composition according to the present invention has a tensile strength,
Extremely good rebound resilience and heat generation properties.

The rubber composition of the present invention is particularly suitable for use in tie A7, mainly tire treads, and has great industrial significance.

Margin below Table 4

Claims (1)

[Claims] 1 Styrene and butadiene are copolymerized in a hydrocarbon solvent using an organolithium catalyst, and the amount of bound styrene is 5 to 4.
5% by weight, vinyl bond in butadiene moiety 10-70%
, carbon disulfide, a xanthogen compound, and a dithioic acid compound are added to a living polymer whose molecular weight distribution (Mw/Mn) expressed by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) by GPC is 1.2 to 3. Raw material rubber 10 containing at least 10% by weight of a polymer having a Mooney viscosity of 20 to 150 and having a C=S bond introduced into the molecule by reacting
A rubber composition suitable for a tire tread, which contains 10 to 100 parts by weight of carbon black, 0.3 to 5 parts by weight of sulfur, and a vulcanization accelerator.