JPH0755964B2 - Method for producing improved rubbery polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a conjugated diene rubbery polymer having improved processability and vulcanization properties, and more specifically, excellent processability during compounding and kneading, The present invention also relates to a method for producing a rubber-like polymer having excellent impact resilience and heat generation of a vulcanized product. The vulcanized rubber using the rubber-like polymer is suitable for tire applications centered on tire treads.

[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 to reduce the rolling resistance of automobile tires, including, for example, a method of improving the tire structure and an improvement of vulcanized rubber used in the tire tread.

Among these attempts to reduce rolling resistance of tires, as a method for improving vulcanized rubber, that is, a method for reducing the energy loss of vulcanized rubber to improve 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 of 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 to date, by using a polymer having a higher molecular weight than before, the impact resilience 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. .

On the other hand, there are some known techniques for improving processability by changing the structure of a polymer used as a raw material rubber. For example, Japanese Examined Patent Publication (Kokoku) No. 49-36957 discloses a method for improving processability by using a branched polymer by using tetrahalosilane, trihaloalkylsilane or the like as a coupling agent. In the case of the polymer obtained by the method, the impact resilience of the vulcanized product is not sufficient and it is unsatisfactory for improving the rolling resistance.

It is also known that the processability can be improved by broadening the molecular weight distribution of the polymer or increasing the degree of branching. However, when the rubber-like polymer obtained by these methods is used, The impact resilience of sulphur is comparable to that before the improvement of workability.

JP-A-57-87407 and JP-A-58-162605 disclose that when a styrene-butadiene copolymer rubber having an increased vinyl content is tin-coupled to form a branched styrene-butadiene copolymer rubber, a cup is used. It has been shown that rolling resistance is improved by adding butadienes immediately before the ring reaction and conducting polymerization. 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.

Moreover, after the copolymerization of all of styrene and a part of butadiene is initiated by a catalyst composed of an organolithium compound and a Lewis base, the remaining butadiene is continuously or intermittently supplied under specific conditions, and A branched random styrene-butadiene copolymer obtained by adding a polyfunctional coupling agent after the completion of the polymerization has been proposed (JP-A-59-140211). Although this polymer showed some excellent performances such as impact resilience and low heat buildup, the tire market needs are advanced and further improvement is needed.

Therefore, there has been a demand for the appearance of a rubber-like polymer that does not complicate the manufacturing method, does not reduce the workability, and can further improve the rolling resistance.

[Problems to be solved by the invention]

The present invention has been made in view of the above points, and has been made to obtain a rubber-like polymer having improved processability at the time of compounding and kneading, impact resilience of a vulcanized product, heat generation property, and the like.

[Means and Methods for Solving Problems]

The present invention has been completed based on the finding that a styrene-butadiene copolymer rubber having a specific polymer structure satisfies the above object.

That is, the present invention copolymerizes butadiene and styrene in a hydrocarbon solvent using an organolithium catalyst. (1) The content of bound styrene is 10 to 50% by weight, and the content of 1,2-vinyl bond in the butadiene portion is The amount is less than 50%,
The isolated styrene analyzed by GPC of ozonolysis is 40% by weight or more of the total bound styrene, and the long-chain block styrene is 5% by weight or less of the fully bound styrene. (2) 10 to 50 of the molecules constituting the polymer % By weight is branchedly bonded by a trifunctional or higher functional branching agent, and (3) at least 20% by weight of the molecule constituting the polymer has the general formula (R ₁ ) _l (R ₂ ) _m Sn (X) _n [ In the formula, R ₁ R ₂ is an alkyl group, an aryl group, a benzyl group, an alkoxy group, X is a halogen atom, l and m are 0 or an integer of 1 or more, and n is 1 or 2, l + m + n = 4] The active tin compound is added and the constituent molecules are linearly bound, and among the molecules subjected to the treatment of (4), (2) or (3), the molecule bound to the active tin compound is a polymer. At least 30% by weight of the constituent molecules, (5) Mooney viscosity Is 25 to 150 is to provide a method of manufacturing a rubber-like styrene-butadiene copolymer.

10 to 100 parts by weight of carbon black, 0.3 to 5 parts by weight of sulfur, a vulcanization accelerator and an organic carboxylic acid are mixed with 100 parts by weight of a raw rubber containing at least 10% by weight of this copolymer in a rubber component. The composition is a rubber composition suitable for tire applications, mainly tire treads.

The present invention will be described in detail below.

The rubber-like styrene-butadiene copolymer obtained by the production method of the present invention (hereinafter referred to as the rubber-like copolymer of the present invention) specifies styrene and butadiene in a hydrocarbon solvent with a catalyst composed of organic lithium and a Lewis base. By copolymerizing the obtained completely random-rubbery living polymer with a trifunctional or higher functional branching agent and a monofunctional or difunctional specific active tin compound. It can be obtained by using a part of the living polymer as a branched polymer and the remaining part or most of the living polymer as an unbranched tin addition polymer.

Examples of the organolithium catalyst used in the present invention include monoalkyllithium compounds such as n-butyllithium, sec-butyllithium and n-propyllithium.

In the polymerization, as a co-catalyst component, diethyl ether, dimethoxyethane, diglyme, ethers such as tetrahydrofuranyl, triethylamine, amines such as tetramethylethylenediamine, hexamethylphosphortriamide, sodium salt or potassium dodecylbenzenesulfonic acid. Add Lewis base, such as salt, alcoholate such as sodium butoxide.

The polymerization is carried out in an inert hydrocarbon solvent such as benzene, toluene, hexane and cyclohexane. The polymerization temperature is generally in the range of 30 ° C to 180 ° C, and preferably 30 ° C to 150 ° C in order to prevent deactivation of the active end.

The bound styrene content of the rubbery copolymer of the present invention is 10 to 50.
%, Preferably 13-40% by weight. The bound styrene content of the rubbery copolymer is determined by the feed composition of the monomer during polymerization, and the tensile strength is less than 10% by weight,
The modulus and abrasion resistance are insufficient, and when it exceeds 50% by weight, performances such as heat generation and impact resilience deteriorate. More preferably,
15 to 35% by weight. Further, the 1,2-vinyl bond in the butadiene portion is 50% or less, preferably 13 to 48%, and when the 1,2-vinyl bond in the butadiene portion exceeds 50%, the abrasion resistance decreases. If the 1,2-vinyl bond is reduced, the wet skid performance is deteriorated, and in either case, the excellent performance of the copolymer of the present invention cannot be obtained. More preferably, it is 15 to 45% by weight. The 1,2-vinyl bond is controlled by the amount of Lewis base which is a promoter component and the polymerization temperature.

The styrene chain distribution, which is a measure of the randomness of the styrene-butadiene copolymer of the present invention, is analyzed by gel permeation chromatography of the low temperature ozonolysis product of the copolymer. This method was developed by Tanaka et al., And the chain distribution of styrene is 2
All the heavy bonds are analyzed by GPC by decomposing products obtained by ozone cleavage. (Macromolecules, 1983,16,1925).

The rubber-like polymer of the present invention has 40% by weight or more of the total styrene content of isolated styrene analyzed by this method, preferably
The content of long-chain block styrene, that is, styrene having a chain of styrene units of 8 or more, is 50% by weight or more, and 5% by weight or less, preferably 2.5% by weight or less, based on the total styrene. Whether the isolated styrene is less than 40% by weight or the long-chain block styrene is more than 5% by weight, the rubber of the present invention has excellent properties such as high impact resilience, low heat buildup and high wet skit resistance. The balance of sex is lowered, which is not preferable.

In the present invention, a method of copolymerizing styrene and butadiene to obtain a completely random-rubbery living polymer is disclosed in JP-A-2006-29187.
The method of 57-100112 or the method of JP-A-59-140211 is preferable.

The Mooney viscosity of the living polymer before the reaction with the active compound is preferably in the range of about 3 to 60 from the viewpoint of vulcanization properties or processability of the finally obtained polymer. In particular
A range of 10-50 is preferred.

Further, the molecular weight distribution of this living polymer is preferably relatively narrow when the impact resilience or exothermicity of the vulcanizate of the final polymer is important, and the range is Mw / Mn of 1.6 or less, preferably 1.4 or less. When the impact resilience of the vulcanized product of the final polymer or the balance between heat generation and processability is emphasized, the range is such that Mw / Mn is 1.6 or more and 3 or less, preferably 1.8 or less.
~ 2.5.

The rubber-like polymer of the present invention comprises a polymer having a living active terminal obtained by the above-mentioned polymerization method, a trifunctional or higher functional branching agent, and a monofunctional or difunctional specific active tin compound. Can be obtained by converting a part of the living polymer into a branched polymer and the remaining part or most of the living polymer into a non-branched tin addition polymer.

The number of trifunctional or higher branching agents used in the reaction is 3 in one molecule.
Compounds containing three or more halogen-tin bonds, halogen-silicon bonds, halogen-germanium bonds, alkoxy-tin bonds, aryl-tin bonds, benzyl-tin bonds, dicarboxylic acid diesters, and three or more epoxy groups A compound, a compound containing three or more carbonyl groups, a compound containing three or more isocyanate groups, and the like are used. Of these compounds, halogen-containing compounds having a very fast reaction rate with a living lithium terminal are preferred.
Examples thereof include compounds containing 3 or more tin bonds and halogen-silicon bonds in the molecule, dicarboxylic acid diesters and compounds containing 3 or more epoxy groups. 1 is particularly suitable
It is a compound having three or more halogen-tin bonds or halogen-silicon bonds in the molecule.

Specifically, tin tetrachloride, monobutyl tin trichloride, silicon tetrachloride, ethylenebistrichlorosilane, diethyl adipate, etc. are preferably used.

A polymer bonded in a branched form by reacting with a trifunctional or higher functional branching agent is at least 10% of the molecules constituting the rubber-like polymer.
% By weight.

If the amount of the polymer molecule coupled with a trifunctional or higher functional branching agent is less than 10% by weight, cold flow easily occurs and the processability is insufficient, preferably 15% by weight or more, more preferably 20% by weight or more. .

On the other hand, less than 50% of branched polymer molecules are coupled with a trifunctional or higher functional branching agent. In order to obtain the high impact resilience and low heat buildup of the present invention, it is preferably less than 40%.

On the other hand, the substantially monofunctional or difunctional specific tin compound used to form the linear polymer molecule having tin bound thereto in the present invention has the general formula (R ₁ ) _l (R ₂ ) _M Sn
(X) _n [R ₁ and R ₂ are an alkyl group, an aryl group, a benzyl group, an alkoxy group, X is a halogen atom, and l and m are 0.
Or a compound represented by an integer of 1 or more, n = 1 or 2, l + m + n = 4]. Specific compounds include trimethyltin chloride, tributyltin chloride, trioctyltin chloride, triphenyltin chloride, dibutyltin dichloride, dioctyltin dichloride, diphenyltin chloride, phenyltributyltin, methoxytributyltin, and the like.

The linear polymer molecule bound to tin in the present invention is at least 20% by weight of the molecule constituting the polymer. If the amount of the linear polymer molecule to which these tin compounds are added is less than 20% by weight, the effect of improving the impact resilience is small, and the amount is preferably at least 30% by weight.

When the trifunctional or higher functional branching agent is an active tin compound, a monofunctional or bifunctional specific tin compound is substantially added to the molecule coupled by the trifunctional or higher functional tin compound. The total of the linear polymer molecules, that is, the polymer molecules bound to the active tin compound is at least 30% by weight of the molecules constituting the polymer, and the trifunctional or higher functional branching agent is a compound other than the active tin compound. In this case, the final rubber composition is such that the linear polymer molecule to which the specific monofunctional or difunctional tin compound is added is at least 30% by weight of the molecule constituting the polymer. It is necessary in terms of the balance between the processability and the impact resilience or heat resistance of the vulcanizate, and it can be said that at least 50% by weight of the polymer molecules are preferably treated with the active tin compound.

The reaction with such an active compound is carried out subsequent to the above-mentioned polymerization reaction, and the reaction temperature is within the same range as the polymerization reaction.

The reaction between the living polymer and the tin-halogen bond reacts very quickly and instantaneously, and the aryl-tin bond, the alkoxy-tin bond and the benzyl-tin bond react at a slightly slower rate. Therefore, in order to obtain a rubber-like polymer composed of the branched component of the present invention and the linear component to which the active tin compound is added, the reaction with the living polymer is substantially monofunctional with the trifunctional or higher functional branching agent. A specific or bifunctional tin compound may be reacted at the same time, but a trifunctional or higher functional branching agent is preferably added first, and then substantially monofunctional or difunctional specific tin compound is added. The compound is reacted in an amount of 0.5 mol or more based on 1 mol of the residual living polymer. When the molar ratio of the living polymer to the specific monofunctional or bifunctional tin compound is out of this range and the molar ratio is too small, the number of branched polymers increases and the Mooney viscosity of the polymer increases, resulting in processing. In addition to the decrease in heat resistance, the properties such as impact resilience and low heat build-up decrease. On the other hand, if the tin compound is reacted in an amount of 1 mol or more, the amount of unreacted compound remains, resulting in loss, which may cause problems such as corrosion of the apparatus.

Since the reaction between the living polymer and the active tin compound is almost quantitative, the amount treated with the above active tin compound can be controlled by the equivalent ratio of active lithium and each tin compound. However, compared to the amount of lithium compound used at the start of polymerization, the amount of active lithium is generally small due to the influence of trace impurities contained in the polymerization system. The amount of compound used is adjusted.

Amount of polymer molecules coupled by a trifunctional or higher functional branching agent, amount of polymer molecules linearly linked by a bifunctional tin compound, and a polymer with or without a monofunctional tin compound added. The amount of the polymer can be determined by separating them by GPC (gel-permeation chromatograph) or comparing GPC curves before and after the reaction.

The rubbery polymer of the present invention obtained as described above has a Mooney viscosity due to its processability and vulcanization physical properties. Is in the range of 25 to 150. If the Mooney viscosity is less than 25, the resulting vulcanizate has a problem of tensile strength or abrasion resistance, and if the Mooney viscosity exceeds 150, the processability is poor. The Mooney viscosity is preferably 30 to 100, and more preferably 35 to 80.

The weight average molecular weight (▲ ▼) of the rubber-like polymer of the present invention measured by GPC and the number average molecular weight (▲ ▼)
The ratio (▲ ▼ / ▲ ▼) to ▼) is generally in the range of 1.3 to 3.5 according to the above manufacturing method,
In particular, it is preferable that ▲ ▼ / ▲ ▼ is in the range of 1.3 to 2.0 in view of impact resilience and exothermicity of the obtained vulcanized rubber, and when importance is attached to the balance between impact resilience and exothermicity and processability, / ▲ ▼ is preferably in the range of 2.0 to 3.0.

The rubber-like polymer of the present invention may be used alone or in a blend with another rubber. When blended with another rubber, the rubber-like polymer of the present invention is used in an amount of 10% by weight or more based on the raw rubber. If it is less than 10% by weight, the balance of high impact resilience, low heat buildup and high wet skid resistance, which are excellent properties of the composition of the present invention, is deteriorated.

Other rubbers that can be used with the rubbery polymer of the present invention include various rubbers such as natural rubber, synthetic cis-polyisoprene, styrene-butadiene copolymer rubber, and polybutadiene rubber which are vulcanized by sulfur. The rubber-like polymer of the present invention, alone or blended with another rubber, becomes a composition suitable for a tire tread composed of carbon black, a vulcanizing agent, a vulcanization accelerator and an organic carboxylic acid.

The amount of carbon black used to make the composition using the rubbery polymer of the present invention is preferably 100% rubber.
10 to 100 parts by weight of carbon black is used with respect to parts by weight. If it is less than 10 parts by weight, the tensile strength and abrasion resistance are not sufficient, and if it exceeds 100 parts by weight, the rubber elasticity is significantly lowered, which is not preferable. It is more preferably 20 to 80 parts by weight.

Iodine adsorption amount (IA) of carbon black used in preparing a composition using the rubber-like polymer of the present invention 40 mg / g
Above and oil absorption of dibutyl phthalate (DBP) 70ml / 100g
The above carbon black is used. Such a carbon black is a carbon black having a small particle size and a high structure, and in other cases, the high balance of high tensile strength, high impact resilience and abrasion resistance of the present invention may not be obtained. . IA is 60mg / g or more and DBP is 80m
It is carbon black of l / 100g or more. Examples of these carbon blacks include those called HAF, ISAF, and SAF.

In preparing a composition using the rubbery polymer of the present invention,
Sulfur is 0.1 to 5 as a vulcanizing agent for 100 parts by weight of the raw rubber.
Used in parts by weight.

When the amount of sulfur is small, tensile strength, impact resilience and abrasion resistance are insufficient, and when it is too large, rubber elasticity is reduced. Preferably 0.5 to
2.5 parts by weight. Further, as a vulcanization accelerator, one or more selected from sulfenamide-based, guanidine-based, thiuram-based and the like is used in an amount of 0.05 to 2 per 100 parts by weight of the raw rubber component.
Parts by weight can be used.

In the vulcanized rubber composition, an organic carboxylic acid typified by stearic acid is used as a vulcanization aid or a processing aid. In the rubbery polymer of the present invention, such an organic carboxylic acid is particularly preferable. , Reacts with the tin compound bound to the polymer, and the reaction product increases the interaction between the rubbery polymer and the reinforcing carbon black, and as a result, features such as impact resilience, low heat buildup, and tensile strength are exhibited. It

The organic carboxylic acid is used in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the raw rubber.

The composition using the rubbery polymer of the present invention is intended to be one that is usually used as a rubber compound as a process oil,
It is used according to the application. Process oils are divided into paraffinic, naphthenic and aromatic based on their chemical structure. Aromatics are used in applications where tensile strength and wear resistance are important, and naphthenes are used in applications where impact resilience and low temperature properties are important. A paraffin type is preferably used. The amount is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the raw rubber, and 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 is not expressed, On the other hand, if it exceeds 100 parts by weight, the tensile strength, impact resilience and hardness are significantly lowered, which is not preferable.

Further, if necessary, the rubber composition used in a usual rubber composition is used in the rubber composition of the present invention in an appropriate amount depending on the purpose of use.

The composition of the copolymer rubber of the present invention is obtained by kneading the above-mentioned components by a known mixer using a known mixer for the rubber industry, such as an oven roll and an internal mixer. The rubber product obtained through the vulcanization process exhibits excellent performance as compared with the rubber products obtained from conventionally known rubber compositions. Above all, it exhibits particularly high impact resilience, low heat build-up, tensile strength, and wet skid properties. Therefore, as described above, it is suitable for the tread of tires, particularly fuel-efficient tires, all-season tires,
It is used for cap treads and under treads of high-performance tires. In addition to its excellent performance, it is also used for tire parts such as tire sidewalls, carcasses, cushion rubbers, anti-vibration rubbers, industrial products, etc. It goes without saying that it can be used.

[Examples] Examples will be shown below, but these show the present invention more specifically and do not limit the scope of the present invention.

Example 1 and Comparative Example 1 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 g, and tetrahydrofuran 38 g, the temperature was kept at 40 ° C., and then 0.52 g of n-butyl lithium was injected to start the polymerization, and thereafter the polymerization temperature was adiabatically changed. Was raised. Internal temperature is 75 ° C
Then, a mixture of 138 g of butadiene and 322 g of cyclohexane was added over 15 minutes using a metering pump, and 1 minute after the end of addition, 0.185 g of tin tetrachloride (0.35 equivalent to Li) was added, After 1 minute, 1.726 g of triphenyl tin chloride (0.55 mol with respect to Li) was added, and 20
After reacting for 8 minutes, the polymer solution was added with 8 g of antioxidant.
After adding BHT, the solvent was removed by heating and the polymer was recovered. The polymer obtained (Material A) has a Mooney viscosity. 55, the styrene content is 15% by weight, the microstructure of the butadiene part is 1,4-trans bonds 34%, 1,4-cis bonds 23
%, 1,2 vinyl bond was 43%. Also, Mw / Mn = 1.60, indicating 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, column
10 ⁴ , 10 ⁵ , 10 ⁶ , 1 each, solvent, tetrahydrofuran, detector: differential refractometer) were used and calculated by a method using a calibration curve with polystyrene as a standard substance.

In addition, the isolated styrene obtained from GPC of ozone decomposition products was 67% by weight based on the total styrene, and long-chain block styrene was
It was 0.8% by weight.

The Mooney viscosity of the polymer immediately before the addition of tin tetrachloride was 22, and the Mw / Mn = 1.10.

Further, as in the case of obtaining the sample A, various methods are used,
Polymers within the scope of the invention and polymers for comparison were obtained by batch polymerization as shown in Table 1.

The analytical values are shown in Table 1.

Abbreviations in Table 1 THF: Tetrahydrofuran phm: parts by weight per 100 parts by weight of monomer.

The cold flow property is evaluated by sticking a rectangular parallelepiped rubber on the slope and observing the state after 8 hours at room temperature. Those that are significantly deformed are inferior, and those that are slightly deformed are good.

In Comparative Example 1-3 (Sample F), all of the monomers were charged into the reactor at the start of polymerization, and then n-butyllithium was injected to initiate the polymerization. It is out of range.

Example 2 and Comparative Example 2 A standard of ASTM-D-3403-75 was prepared by using various rubber-like polymers shown in Table 2 as raw rubbers and using a Banbury mixer for testing having an internal volume of 1.7. Compounds were obtained by the method B of the compounding and mixing procedure, 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: Lupke method according to JIS-K-6301, except that the impact resilience at 70 ° C is measured by preheating the sample in an oven at 70 ° C for 1 hour and then quickly taking it out.

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

(4) Wet skid resistance A Skidley London portable skid tester was used, and a safety walk (3M) was used as the road surface, and the measurement was performed according to the method of ASTM-E-808-74. S
It was displayed as an index with the measured value of BR1502 as 100.

From the results shown in Table 3, the characteristics of the rubber using the rubber-like polymer of the present invention are clear as follows.

From the comparison between Example 2-1 (Sample A) and Comparative Example 2-1 (Sample D), the combined use of the tetrafunctional compound and the monofunctional compound improved the impact resilience and heat generation. There is.
On the other hand, in Comparative Example 2-2 (Sample E), although the impact resilience or exothermicity was good, the compound Mooney viscosity was high, the processability was poor, the cold flow property was poor, and only the monofunctional compound was used. It shows some drawbacks.

Comparative Example 2-3 (Sample F) is out of the scope of the present invention because it has a large amount of long-chain block styrene, and is inferior in impact resilience and heat generation. Comparative Example 2-4 (Sample G) is polybutadiene, which is outside the scope of the present invention, and the tensile strength is poor. Comparative Example 2-5 (Sample H) has a styrene content outside the range of the present invention, and is inferior in impact resilience and heat generation.

The effect of the present invention is exhibited in other examples as well, and the impact resilience is high and the exothermicity is low.

The vulcanized rubbers of these examples have a good balance between impact resilience and heat buildup, which are measures of rolling resistance, and wet skid resistance, and can be said to be particularly suitable for tires.

Table-2 Formulation No. 1 Raw rubber 100 parts by weight Aromatic oil ^{* 1} 10 parts by weight N-339 Carbon black ^{* 2} 50 parts by weight Stearic acid 2 parts by weight Zinc white 3.5 parts by weight Accelerator CZ ^{* 3} 1.3 parts by weight Sulfur 2 Parts by weight * 1 Kyodo Petroleum X-140 * 2 Iodine adsorption amount (IA) 90mg / g Dibutylphthalate adsorption amount (DBP) 119ml / 100g * 3 N-cyclohexyl-2-benzothiazyl sulfenamide Vulcanization condition: 160 ° C × 20 minutes Example 3 and Comparative Example 3 As shown in Table 4, sample A or D and another rubber were blended to form a rubber component, and a composition was prepared according to the formulation shown in Table 2. Physical properties were measured in the same manner as in Example 2. did.

As is clear from the results in Table 4, the polymer of the present invention is excellent in the balance between the impact resilience of the vulcanizate and the wet skid characteristics even when blended with other rubbers, and is useful as a vulcanized rubber. To bring.

Example 4 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, n-hexane as solvent 109.3g /
min, n-butyllithium as catalyst for all monomers
0.065phm, 0.030phm of tetramethylethylenediamine are fed from the bottom of the 1st phase by a metering pump,
Purification from 2/3 of the height of the first reactor 1,3
-Butadiene 4.6 g / min and n-hexane 10.7 g / min were fed, stirring rotation speed 250 rpm, internal temperature 105 ° C average residence time
Polymerization was carried out for 45 minutes. Polymer is sampled at the first outlet, Mooney viscosity is measured, Got Further, the polymer solution was continuously introduced into the bottom of the second unit, and 0.0065 phm of silicon tetrachloride (0.1 to Li was added from the bottom).
(5 equivalents) were added continuously, and 0.293 ph of triphenyl tin chloride was added at a position 2/3 of the height of the second reactor.
A solution of m (0.59 equivalent to Li) was continuously added to carry out the reaction. The temperature of the second unit was controlled at 100 ° C. BHT0.75phm continuously to the polymer solution that came out of the second unit.
Was added, the solvent was removed by heating, and the polymer was recovered.
The polymer obtained has a Mooney viscosity. Styrene content 25% by weight, the microstructure of the butadiene part is 1,4-trans bond 46%, 1,4-cis bond 32%, 1,2-
The vinyl bond was 22%. The Mw / Mn was 2.2, indicating that the GPC curve had one peak. In addition, the isolated styrene obtained from GPC of ozone decomposition products was 65% of the total styrene.
%, And long-chain block styrene was 0.2% by weight. A compound was obtained from the obtained polymer in the same manner as in Example 2, and the compound was vulcanized to measure each physical property. The results are shown in Table-5.
Shown in.

Comparative Example 4-1 The same procedure as in Example 4 was performed. However, all of the monomers were fed from the first reouter bottom, and the stirring speed of the first set was set to 25 rpm, which was 1/10. The obtained polymer has many long-chain block styrenes. The results are shown in Table-5.

Comparative Example 4-2 The same procedure as in Example 4 was performed. However, the addition of triphenyltin chloride in the second reactor was not performed. The results are shown in Table-5.

As is clear from the results in Table 5, the polymer of the present invention is extremely excellent in the balance of impact resilience and wet skid of the vulcanized product, and is also excellent in tensile strength.

[Effects of the Invention] The rubber-like polymer according to the present invention has improved cold flow properties and roll processability as described above, and the vulcanized product has impact resilience and exothermic properties and wetness which are measures of rolling resistance.
It has a good balance of skid resistance and also exhibits these good properties in blends with other rubbers. The vulcanized rubber using the rubbery polymer of the present invention is particularly suitable for tire applications centering on tire treads and has great industrial significance.

Claims (1)

[Claims] 1. Copolymerizing butadiene and styrene in a hydrocarbon solvent using an organolithium catalyst. (1) The bound styrene content is 10 to 50% by weight, and the butadiene portion contains 1,2-vinyl bonds. The amount is less than 50%,
The isolated styrene analyzed by GPC of ozonolysis is 40% by weight or more of the total bound styrene, and the long-chain block styrene is 5% by weight or less of the fully bound styrene. (2) 10 to 50 of the molecules constituting the polymer % By weight is branchedly bonded by a trifunctional or higher functional branching agent, and (3) at least 20% by weight of the molecule constituting the polymer has the general formula (R ₁ ) _l (R ₂ ) _m Sn (X) _n [ In the formula, R ₁ R ₂ is an alkyl group, an aryl group, a benzyl group, an alkoxy group, X is a halogen atom, l and m are 0 or an integer of 1 or more, and n is 1 or 2, l + m + n = 4] The active tin compound is added and the constituent molecules are linearly bonded, and among the molecules subjected to the treatment of (4) (2) or (3), the molecule bonded to the active tin compound is a polymer. At least 30% by weight of the constituent molecules, (5) Mooney viscosity Process for preparing a rubbery styrene-butadiene copolymer is 25 to 150.