JPH0657764B2 - Rubber composition for tire tread - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubbery polybutadiene or styrene-butadiene copolymer composition produced using an organic lithium catalyst, which is suitable for a tread of a fuel-efficient tire.

[Conventional technology]

In recent years, due to the soaring price of crude oil, energy conservation has been advocated in various fields of industry, and many attempts have been made to reduce gasoline consumption in automobiles as well, improvements in engines, weight reduction of car bodies and tires, Air resistance of vehicle bodies and rolling resistance of tires have been reduced.

Among the energy-saving efforts associated with these cars,
Various attempts have been made as methods for reducing rolling resistance of automobile tires, and examples thereof include a method of improving a tire structure and an improvement of a vulcanized rubber used for a tire tread.

Among the attempts to reduce the rolling resistance of these tires, as a method for improving the vulcanized rubber, that is, a method for reducing the energy loss of the vulcanized rubber to improve the impact resilience or heat generation, Methods for improving the raw material rubber used for rubber, changing the type of carbon black, and reducing the amount of carbon black or oil used for vulcanized rubber to achieve high impact resilience have been studied.

Among the above-mentioned methods of improvement, as a method for improving the raw material rubber, from the knowledge about the physical properties of the raw material rubber and the physical properties of the vulcanized rubber up to now, by using a polymer having a higher molecular weight than before, the impact resilience is improved. Although the above-mentioned improvement can be made, it cannot be greatly improved because the Mooney viscosity of the rubber and the compound increases and the processability decreases. On the other hand, change the recipe
Even in the method of reducing the blending amount of oil and carbon black, the Mooney viscosity of the blend is increased, and in this case, the processability is deteriorated. In any method, it is difficult to improve without sacrificing the processability. .

By the way, in recent years, it has been found that a random styrene-butadiene copolymer rubber having a large number of vinyl bonds and having a branched structure can be suitably used for tire applications, rubbers having various structures have been studied, and various proposals have been made. For example, when a styrene-butadiene copolymer rubber with a high vinyl content is tin-coupled to form a branched styrene-butadiene copolymer rubber, rolling resistance is improved by adding butadiene immediately before the coupling reaction and polymerizing. The proposed method has been proposed (JP-A-57-87407 and JP-A-58-16260).
Five). However, even with this method, the rolling resistance cannot be said to be sufficiently improved, and there is a problem that the manufacturing method becomes complicated.

Further, a completely random styrene produced by continuously introducing a monomer into a polymerization zone having a high stirring efficiency controlled at a temperature of 80 ° C. or higher by a catalyst composed of an organolithium compound and a Lewis base, and allowing the polymerization to proceed. A butadiene copolymer rubber has been proposed (JP-A-57-100112).
This polymer exhibited excellent properties such as tensile strength, impact resilience, low heat buildup, abrasion resistance, and wet skid resistance.
However, the impact resilience and the low heat buildup have to be further improved.

In addition to this, various methods for introducing functional groups into the ends of the living polymer have been proposed as methods for improving the raw material rubber. For example, there is a method in which a living polymer is produced using a bifunctional anion initiator and then organic sulfenyl chloride is allowed to act to introduce active groups at both ends of the molecule (Japanese Patent Publication No. 44-855). However, in this method, there is a problem in industrial use that a polymer having a high molecular weight and living ends at both ends is difficult to obtain, and organic sulfenyl chloride is difficult to handle, and the obtained polymer also has tensile strength and modulus. It was inadequate.
Furthermore, there is a method of introducing an amino group at the terminal (Japanese Patent Laid-Open No. 59-59160).
-38209, JP-A-58-162604, JP-A-60-137913, JP-A-60
-137914) In addition to the drawback that the Mooney viscosity of the compound remarkably increases and the workability is impaired, improvement in impact resilience, low heat buildup, abrasion resistance, wet skid property, etc. was insufficient.

[Problems to be solved by the invention]

Therefore, the present inventors have proposed a styrene-butadiene copolymer rubber composition having excellent performances such as wet skid property, workability and the like, tensile strength, impact resilience, low heat buildup, and abrasion resistance. As a result of intensive studies for development, the inventors have invented a specific polybutadiene and styrene-butadiene copolymer rubber composition.

[Means and Actions for Solving Problems]

That is, the present invention is a rubber-like polybutadiene polymerized in a hydrocarbon solvent using an organolithium catalyst or a rubber-like butadiene-styrene copolymer having a styrene content of 45% by weight or less, wherein the vinyl bond of the butadiene portion is 10 to 70
%, Molecular weight distribution (Mw / Mn) represented by the ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) by GPC
The living polymer of 1.2 to 3 is reacted with carbodiimides to modify the end of the polymer. 100 parts by weight of raw material rubber containing at least 10% by weight of a polymer having a Mooney viscosity of 20 to 150 is added to carbon black of 10 to 100. A rubber composition suitable for a tire tread containing 1 part by weight, 0.1 to 5 parts by weight of sulfur and a vulcanization accelerator.

Hereinafter, the present invention will be described in detail.

The organolithium catalyst used in the present invention is a hydrocarbon having at least one or more lithium atoms bonded thereto, such as ethyllithium, propyllithium and n-.
There are butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, propenyllithium, hexyllithium, etc., and particularly preferable are n-butyllithium and sec-butyllithium. This organolithium catalyst can be used not only as one kind but also as a mixture of two or more kinds. The amount of the organolithium catalyst used depends on the Mooney viscosity of the polymer produced, but is usually 0.3 to 3 mmol, preferably 0.5 to 1.5 mmol, per 100 g of the monomer.

As the hydrocarbon solvent used in the present invention, n-butane, n-pentane, iso-pentane, n-hexane,
It is n-heptane, iso-octane, cyclohexane, methylcyclopentane, benzene, toluene and the like, and particularly preferable solvents are n-hexane, n-heptane and cyclohexane. This hydrocarbon solvent may be used alone or in combination of two or more kinds, and it is usually used in an amount of 1 to 20 parts by weight per 1 part by weight of the monomer.

The bound styrene content of the styrene-butadiene copolymer rubber of the present invention is 45% by weight or less. If it exceeds 45% by weight, heat generation increases and impact resilience also decreases, resulting in poor performance. on the other hand,
When the amount of bound styrene is low, the tensile strength decreases, and it is preferably 5% by weight or more. From the viewpoint of the balance among wet skid, tensile strength, impact resilience and heat generation, a particularly preferred range is 10 to 35% by weight.

The vinyl bond of the butadiene portion of the polybutadiene or styrene-butadiene copolymer rubber of the present invention is 10 to 70%, preferably 15 to 50%. Wet skid resistance is low when there are few vinyl bonds, while abrasion resistance decreases when there are many vinyl bonds. Particularly preferably, it is in the range of 20 to 45%.

The molecular weight distribution of the styrene-butadiene copolymer rubber of the present invention is calculated using GPC using a calibration curve of standard polystyrene, and is represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). Distribution size (Mw /
Mn) is 1.2 to 3, preferably 1.5 to 2.5.
If the molecular weight distribution is small, the processability is poor, and if the molecular weight distribution is large, the impact resilience and low heat buildup are poor. The molecular weight distribution by GPC may be one or two. Usually, a linear or branched coupling polymer is prepared by using a coupling agent such as silicon tetrachloride, alkyl trichloride, dialkyl silicon chloride or tin chloride, which is used for improving processability. Any method may 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 distributed by GPC of the low temperature ozonolysis product of the copolymer rubber. This method was developed by Tanaka et al., And the chain distribution of styrene was analyzed by GPC, which was a decomposition product obtained by ozone cleavage of all double bonds of butadiene (Macromolecules, 1983, 16, 19).
twenty five). The copolymer rubber of the present invention has an isolated styrene analyzed by this method, that is, styrene having a chain of 1 styrene unit is preferably 40% by weight or more, more preferably 50% by weight or more, of long-chain. Block styrene, that is, 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, based on the total bound styrene. Whether the isolated styrene is less than 40% by weight or the long-chain block styrene is more than 5% by weight, excellent properties of the copolymer rubber of the present invention are high impact resilience, low heat buildup and high wettability. The skid resistance balance is unfavorably lowered.

The carbodiimide used in the present invention is a disubstituted carbodiimide compound having a general formula —N═C═N- bond or a disubstituted carbamide compound having a general formula> N—C≡N bond, including dialkylcarbodiimide and alkylaryl. Carbodiimide, diarylcarbodiimide,
Dialkyl cyanamide, alkylaryl cyanamide,
It is a compound containing diaryl cyanamide and is used as one kind or as a mixture of two or more kinds.

For example, dimethylcarbodiimide, diethylcarbodiimide, dipropylcarbodiimide, dibutylcarbodiimide, dihexylcarbodiimide, dicyclohexylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, methylpropylcarbodiimide, butylcyclohexylcarbodiimide, ethylbenzylcarbodiimide, propylphenylcarbodiimide, phenylbenzylcarbodiimide, dimethylcyanamide. , Diethylcyanamide, dipropylcyanamide, dibutylcyanamide, dihexylcyanamide, dicyclohexylcyanamide, dibenzylcyanamide, diphenylcyanamide,
Examples include methylpropyl cyanamide, butylcyclohexyl cyanamide, ethylbenzyl cyanamide, propylphenyl cyanamide, and phenylbenzyl cyanamide.
Of these, particularly preferred are dicyclohexylcarbodiimide, diphenylcarbodiimide and diphenylcyanamide.

These compounds are based on 1 mol of the living polymer,
It is fed at a rate of 0.2 to 5 mol, preferably 0.3 to 3
It is a molar ratio. The ratio is more preferably 0.5 to 2 mol. In the reaction of living lithium with carbodiimides in the present invention, there is almost no increase in Mooney viscosity after the reaction, and the processability does not decrease. When the amount of feed is small, the effect of improving the physical properties is small. On the other hand, when the amount of feed is large, it is unreacted and the vulcanization time is shortened and the tensile strength is lowered. The reaction between the living polymer and these compounds is extremely rapid, and the reaction temperature is generally room temperature to 120 ° C. and the reaction time is several seconds to several hours. An antioxidant is usually added to a polymer obtained by reacting these compounds with a living polymer to introduce a non-end-modified group, and if necessary, oil-extended, and the solvent is removed by a usual method.

The Mooney viscosity ML (1 + 4,100) of the polybutadiene or styrene-butadiene copolymer rubber used in the present invention, which is obtained by reacting carbodiimides and introducing terminal modifying groups.
C.) is 20 to 150, preferably 25 to 130. If the Mooney viscosity is lower than this, the vulcanized rubber is inferior in tensile strength, abrasion resistance, impact resilience, and low heat buildup.If the Mooney viscosity is higher than this, excessive torque may be applied during kneading with rolls or Banbury, Alternatively, the dispersion of carbon is poor and the performance of the vulcanized rubber is poor.

The polybutadiene or styrene-polybutadiene copolymer rubber modified with carbodiimides used in the present invention is used as a raw material rubber alone or blended with another synthetic rubber or natural rubber. In this case, in order to exhibit the excellent properties of the present invention, it is necessary that at least 10% by weight of the raw rubber is a polybutadiene or styrene-butadiene copolymer rubber modified with the carbodiimides of the present invention.
It is preferably 30% by weight or more.

Other synthetic rubbers or natural rubbers used by blending are emulsion-polymerized styrene-butadiene copolymer rubber, 1,2-vinyl less than 35% solution-polymerized styrene-butadiene copolymer rubber, cis-1,4 polybutadiene rubber, 1,
2 Syndiopolybutadiene rubber, 1,2-vinyl 10% to 90% polybutadiene rubber, synthetic polyisoprene rubber or natural rubber, one or two of which are listed.
More than one species can be used.

The amount of carbon black used in the present invention depends on the raw rubber.
Carbon black is used in an amount of 10 to 100 parts by weight based on 100 parts by weight. If it is less than 10 parts by weight, tensile strength, abrasion resistance, etc. are not sufficient, and if it exceeds 100 parts by weight, the rubber elasticity is remarkably lowered, which is not preferable. It is preferably 20 to 80 parts by weight.

The types of carbon black used in the present invention are
Carbon black having an iodine adsorption amount (IA) of 40 mg / g or more and a dibutyl phthalate oil absorption amount (DBP) of 70 ml / 100 g or more is preferably used. Such a carbon black is a carbon black having a small particle size and a high structure. Other than this, the high tensile strength of the present invention,
A balance of high impact resilience and high wear resistance may not be obtained. IA is preferably 60 mg / g or more and DBP is 80
It is carbon black of ml / 100g or more.

Examples of these carbon blacks include HAF and
There are those called ISAF and SAF.

In the present invention, 0.1 to 5 parts by weight of sulfur is used as a vulcanizing agent with respect to 100 parts by weight of the raw material rubber. When the amount of sulfur is small, tensile strength, impact resilience and wear resistance are insufficient, and when it is too large, rubber elasticity is reduced. It is preferably 0.5 to 2.5 parts by weight.

In the present invention, various conventionally known vulcanization accelerators are used as the vulcanization accelerator, but thiazole vulcanization accelerators are preferably used. What is a thiazole vulcanization accelerator? It is a vulcanization accelerator having a basic structure of (R = alkyl, arylene) group. While these vulcanization accelerators provide the excellent tensile strength, impact resilience, and abrasion resistance of the present invention, other vulcanization accelerators may not provide adequate vulcanization. As these accelerators, a vulcanization accelerator M (2-mercaptobenzothiazole), a vulcanization accelerator DM (dibenzothiazyl disulfide), and a vulcanization accelerator CZ (N-cyclohexyl-2-benzo) are preferable. Thiazyl sulfenamide).

The amount of vulcanization accelerator used is preferably 0.2 to 3 parts by weight per 100 parts by weight of rubber.

In the composition of the present invention, those commonly used as a process oil for compounding rubber are used depending on the purpose and application. Depending on its chemical structure, it is classified into paraffinic, naphthenic and aromatic types. Aromatic type is used for applications where tensile strength and wear resistance are important, and naphthene to paraffin type is used for applications where emphasis is placed on impact resilience and low temperature properties. Is preferably used. The amount is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the raw rubber. If it is less than 5 parts by weight, the workability is poor and the dispersion of carbon black is poor, so that the performance such as tensile strength and elongation does not appear. On the other hand, if it exceeds 100 parts by weight, tensile strength, impact resilience, and hardness are significantly lowered, which is not preferable.

The composition of the copolymer rubber of the present invention, when used, further
Other fillers than carbon black, zinc oxide, stearic acid, antioxidants, antiozonants, if necessary,
Wax or the like can be added.

As fillers other than carbon black, silicic acid,
Silicate, calcium carbonate, titanium oxide, various clays, etc. are used.

The composition of the copolymerized rubber of the present invention is obtained by kneading the above-mentioned components by various known methods using a known mixer for the rubber industry, such as an open roll and an internal mixer. The rubber product obtained through the vulcanization step exhibits excellent performance as compared with the rubber products obtained from conventionally known rubber compositions, the increase in the Mooney viscosity of the compound is small, the processability is extremely excellent, and particularly It has high impact resilience, low heat buildup, tensile strength and wet skid properties. Therefore, it is preferably used for applications in which ordinary polybutadiene or styrene-butadiene copolymer rubber compositions are used.

〔Example〕

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

In the following Examples and Comparative Examples, "parts" means "parts by weight" unless otherwise specified. Also, "phm"
Means "parts by weight per 100 parts of monomer".

Example 1 A stainless steel stirrer having an internal volume of 10 and two reactors with jackets were connected in series, 1,3-butadiene and styrene (75/25 weight ratio) were used as monomers, and n-hexane was used as a solvent. 100 g of n-butyllithium monomer as a catalyst
At a rate of 0.06 g / phm, ethylene glycol dibutyl ether was used as a vinylating agent in an amount of 0.60 phm, and 1,2-butadiene was used as an allene compound in an amount of 0.03 mol per 1 mol of the catalyst to carry out continuous copolymerization. The internal temperature of the first unit was controlled so as to be 100 ° C., and the monomers and the like were supplied by a metering pump so that the average residence time was 45 minutes.

The polymerization rate at the outlet of the first unit was measured by gas chromatography to obtain a butadiene polymerization rate of 97% and a styrene polymerization rate of 95%.

Measure the Mooney viscosity with a Mooney viscometer, Got

Further, the polymer solution was continuously introduced into the second group, and dicyclohexylcarbodiimide was added to the second group in an amount of 0.19 phm (Li
(1 mol relative to 1 mol) was continuously added, and the internal temperature was controlled to 100 ° C.

After adding 2,6-ditertiarybutyl-p-cresol as an antioxidant at the outlet of the second unit, the solvent is removed by steam stripping and the product is dried on a hot roll at 110 ° C to introduce a functional group into the polymer terminal. A styrene-butadiene copolymer rubber was obtained. This is designated as Evaluation Sample A.

The Mooney viscosity of the obtained rubber is measured with a Mooney viscometer, Got Also, 1,2 of the bound styrene and butadiene moieties
The vinyl content was determined by the method of Hampton using an infrared spectrophotometer and obtained 25% by weight of bound styrene and a 1,2-vinyl content of the butadiene part of 29%. The molecular weight distribution was calculated using GPC using a standard polystyrene polymer calibration curve to obtain Mw / Mn: 2.2. Also, the GPC curve showed that the molecular weight distribution was one peak. In addition, the isolated styrene obtained by GPC of ozone decomposed matter was 64 wt% with respect to the total styrene, and the long-chain block styrene was 0.6%.
It was wt%.

Next, using the evaluation sample A as the raw material rubber, (IA): 90 mg /
g, (DBP): 119 ml / 100 g of N339 carbon black with the composition shown in Table 1 and using a test Banbury mixer with an internal capacity of 1.7, ASTM-D-3403-75
Compounds were obtained by the method B of the standard compounding and mixing procedure of 1., these were vulcanized, and each physical property was measured. The measurement was performed by the method described below.

(1) Hardness and tensile strength: In accordance with JIS-K-6301.

(2) Impact resilience: Reyupke method according to JIS-K-6301, except that impact resilience at 70 ° C. is measured by taking out the sample in an oven at 70 ° C. for 1 hour and then quickly taking it out.

(3) Goodrich heat generation Using a Goodrich flexometer, a test was conducted under the conditions of a load of 48 pounds, a displacement of 0.225 inches, a start of 50 ° C and a rotation speed of 1800 rpm, and the temperature rise difference after 20 minutes was expressed.

(4) Wet skid resistance Stanley London portable skid tester is used, and a safety walk (3M) is used as the road surface.
Was measured according to the method of ASTM-E-808-74. It is expressed as an index with the measured value of SBR1502 being 100.

The physical properties are shown in Table 3.

Examples 2 to 4, 7 to 9 and Comparative Examples 1 to 4 The evaluation rubbers were produced in the same manner as in Example 1 except that the method shown in Table 2 was used. The obtained rubbers are referred to as evaluation samples B to D and G to I. Evaluation samples B to D and G
Compounds I to I were used to obtain blends in the same manner as in Example 1 except that the methods shown in Table 3 were used, and these were vulcanized and each physical property was measured. The physical properties are shown in Table 3.

Example 5 Two stirrers having an internal volume of 10 and reactors with jackets were connected in series, and purified 1,3 butadiene as a monomer 17.9 g /
min, purified styrene 7.5g / min, solvent n-hexane 109.3g / min, catalyst n-butyllithium 0.065phm for all monomers, tetramethylethylenediamine 0.030phm from the bottom of the first reactor. Feed with a metering pump, and further feed purified 1,3 butadiene 4.6 g / min and n-hexane 10.7 g / min from the position 2/3 of the height of the first reactor, stirring rotation speed 250 rpm, within Polymerization was carried out at a temperature of 105 ° C and an average residence time of 45 minutes. The polymer is sampled at the outlet of the first unit to measure the Mooney viscosity, Got Further, the polymer solution was continuously introduced into the bottom of the second unit, 0.0065 phm of silicon tetrachloride (0.15 equivalent to Li) was continuously added from the bottom, and the second reactor height was 2 / Dicyclohexylcarbodiimide (0.16 phm (0.75 mol relative to Li)) was continuously added to the 3-position with an n-hexane solution to carry out the reaction. The temperature of the second unit was controlled at 100 ° C. BHT0.75phm was continuously added to the polymer solution having the second group, and the solvent was removed by heating to recover the polymer.

The polymer obtained has a Mooney viscosity. Styrene content is 25% by weight, the microstructure of the butadiene part is 1,4-trans bond 46%, 1,4 cis bond 32%,
The 1,2-vinyl bond was 22%. Also, Mw / Mn is 2.
2, the GPC curve indicated that there was one peak. The isolated styrene determined by GPC of the ozone decomposed product was 65% by weight, and the long-chain block styrene was 0.2% by weight, based on the total styrene. This is designated as Evaluation Sample E.

A compound was obtained from this evaluation sample by the same method as in Example 1, vulcanized, and each physical property was measured.

Table 3 shows the evaluation physical properties of the evaluation sample E.

Example 6 It carried out like Example 5. However, instead of using dicyclohexylcarbodiimide, 0.15 phm of diphenyl cyanamide (0.75 mol relative to Li) was used. The obtained polymer is referred to as Material F. Similarly, the evaluation physical properties are shown in Table 3.

Table 1 Compound No. Raw rubber 100 parts by weight Aromatic oil ^{* 1} 10 parts by weight Carbon black 50 parts by weight Stearic acid 2 parts by weight Zinc white 3.5 parts by weight Accelerator CZ ^{* 2} 1.3 parts by weight Sulfur 2 parts by weight * 1 Joint Petroleum X -140 * 2 N-cyclohexyl-2-benzothiazylsulfenamide Vulcanization condition: 160 ° C x 20 minutes From the results shown in Table 3 above, the characteristics of the rubber composition of the present invention are clear as follows.

Each of Examples 1 to 6 is a composition of the present invention in which a polymer modified with carbodiimides is used as a rubber component.
From the comparison between Examples 1 and 2 and Comparative Example 1 and the comparison between Example 4 and Comparative Example 2, the composition of the present invention has a higher tensile strength, impact resilience, and a higher strength than the composition using the polymer not modified with carbodiimides. The heat buildup is greatly improved.

Example 7 is 31% styrene isolated from ozonolysis-GPC.
The composition of the present invention using a polymer end-modified with a low polymer as a rubber component was slightly inferior to Example 1 in performance, but was extremely superior to Comparative Example 1.

Examples 8 and 9 are rubber compositions in which the polymer according to the present invention is blended with other rubber, and are rubber compositions in which a polymer not modified with carbodiimides is used as a rubber component. In comparison, tensile strength, impact resilience,
Excellent heat generation.

The excellent effects of the present invention are shown in other examples.

Examples 10 and 11 and Comparative Example 5 Cyclohexane 4598 was placed in a reactor equipped with a stirrer with an internal volume of 10.
g, purified 1,3-butadiene 780 g, purified styrene 162
After charging 38 g of tetrahydrofuran and maintaining the temperature at 40 ° C., 0.52 g of n-butyllithium was injected to initiate polymerization, and thereafter the polymerization temperature was adiabatically raised.
From the time the internal temperature reached 75 ° C, 138g of butadiene and 322g
A mixture of g cyclohexane was added over 15 minutes using a metering pump. Maximum temperature of reaction is 100 ℃
Met. 1 minute after the addition was completed, 0.132 g of tin tetrachloride (0.25 equivalent to Li) was added, and 1 minute later, 1.26 g.
Dicyclohexylcarbodiimide (0.75 mol with respect to Li) was added and reacted for 20 minutes, 8 g of BHT as an antioxidant was added to the polymer solution, and then the solvent was removed by heating.
The polymer was recovered. The polymer obtained (Material J) has a Mooney viscosity. 50, styrene content 15% by weight, microstructure of butadiene part is 1,4 trans bond 34%, cis 1,4 bond 23
%, 1,2-vinyl bond was 43%. Also, Mw / M
n = 1.60, showing that the GPC curve has two peaks. The styrene content and the microstructure of the butadiene portion were obtained by measuring the IR spectrum and calculating by the method of Hampton. Mw / Mn is GPC (Shimadzu Corporation, LC-5A, columns 10 ⁴ , 10 ⁵ , 10 ⁶ 1 each)
This was calculated by a method using a calibration curve using standard polystyrene as the solvent, tetrahydrofuran as the solvent, and a differential refractometer as the detector.

The isolated styrene determined by GPC of the ozone decomposed product was 67% by weight, and the long-chain block styrene was 0.8% by weight, based on the total styrene.

The Mooney viscosity of the polymer immediately before the addition of tin tetrachloride was 30 and Mw / Mn = 1.10. Sample J
Sample K (Comparative Example 5) in which dicyclohexylcarbodiimide was not reacted was obtained in the same manner as in the above.
The polymer obtained has a Mooney viscosity. Is 53, styrene content is 15% by weight, microstructure of butadiene part is 1,4-trans bond 34%, cis-1,4 bond
23% and 1,2-vinyl bond 43%. Mw / Mn is
1.65, 65% isolated styrene, 0 for long chain block styrene.
It was 8% by weight. The Mooney viscosity of the polymer immediately before the addition of tin tetrachloride was 30 and Mw / Mn = 1.10. For Samples I and J, Example 1 under the compounding conditions shown in Table 1.
A compound similar to the above was obtained, which was vulcanized and the physical properties were measured.
In Example 11, sample J was used as carbon black (IA): 44 mg / g, (DBP): 114 ml / 100 g of N-.
A blend was obtained in the same manner as in Example 1 except that 550 carbon black was used, and the blend was vulcanized and the physical properties were measured. The evaluation results are shown in Table-4.

Example 12 Cyclohexane 4920 was placed in a reactor equipped with a stirrer and having an internal volume of 10.
g, purified 1,3-butadiene 918 g, purified styrene 162
g, 38 g of tetrahydrofuran, the temperature was kept at 40 ° C., and then 0.52 g of n-butyllithium was injected as a catalyst to initiate the polymerization, and thereafter the polymerization temperature was adiabatically raised. The maximum temperature in the reaction reached 110 ° C, 10 minutes after reaching the maximum temperature, 0.132 g of tin tetrachloride (0.25 equivalent to Li) was added, and 1 minute later, 1.26 g of dicyclohexylcarbodiimide (0.75 mol to Li) was added. Was added and reacted for 20 minutes. Then, the polymer was recovered in the same manner as in Example 9. The polymer obtained (Material L) has a Mooney viscosity. 48, styrene content 15% by weight, microstructure of butadiene part is 1,4 trans bond 35%, cis 1,4 bond 23
%, 1,2-vinyl bond was 42%. Also, Mw / M
n = 1.60, and the GPC curve had two peaks.

Further, the isolated styrene determined by GPC of the ozone decomposed product was 46% by weight and the long-chain block styrene was 7.3% by weight based on the total styrene.

The Mooney viscosity of the polymer immediately before the addition of tin tetrachloride was 33, and Mw / Mn = 1.10. Further, a blend was obtained in the same manner as in Example 1, vulcanized, and each physical property was measured.

The evaluation results are shown in Table-4.

Example 10 was significantly superior to Comparative Example 5 in tensile strength, impact resilience and exothermicity.

Example 11 is a composition of the present invention using N-550 carbon, and although the tensile strength is inferior to that of Example 10, impact resilience,
Both exothermic properties were extremely excellent.

Example 12 is a composition of the present invention using as a rubber component a polymer obtained by subjecting a polymer having 7.3% of long-chain block styrene determined by GPC of an ozone decomposition product to a terminal modification. Comparative Example 5 although slightly inferior to 10
It was extremely superior to.

As described above, the effect of the present invention is clear.

[Effect of the Invention] The rubber composition according to the present invention exhibits excellent performance as compared with rubber products obtained from conventionally known rubber compositions,
The Mooney viscosity of the compound does not increase so much, the processability is extremely excellent, and particularly high impact resilience, low exothermic property, tensile strength and wet skid property are exhibited. Therefore, it is preferably used for applications in which ordinary polybutadiene or styrene-butadiene copolymer rubber compositions are used.

Claims (1)

[Claims] 1. An amount of rubbery polybutadiene or styrene polymerized in a hydrocarbon solvent using an organolithium catalyst is 45.
A rubber-like butadiene-styrene copolymer in an amount of up to 10% by weight, in which the vinyl bond in the butadiene portion is 10 to 70%, GPC
Weight average molecular weight (Mw) and number average molecular weight (Mn)
The molecular weight distribution (Mw / Mn) represented by the ratio is 1.2 to 3
The living polymer, which is a polymer, is modified with carbodiimides to modify the polymer end. Mooney viscosity 20-150
Raw rubber 100 containing at least 10% by weight of polymer
Carbon black 10 to 100 parts by weight, sulfur
A rubber composition suitable for a tire tread, which comprises 0.1 to 5 parts by weight and a vulcanization accelerator.