JPS6023409A - Styrene-butadiene copolymer rubber - Google Patents

Abstract

PURPOSE:The titled rubber useful for tire tread, etc., having a specific bonded styrene content, a specified chain length distribution of bonded styrene, Mooney viscosity, etc., showing low vulcanization hysteresis loss, and improved fraction strength, obtained by using an organolithium compound as a catalyst. CONSTITUTION:The desired rubber obtained by using an organolithium compound as a catalyst preferably by a solution polymerization method, having 10- 45wt%, preferably 15-35wt% bonded styrene content, a chain length distribution of bonded styrene consisting of <50wt%, preferably 25-40wt% short-chain polystyrene of 1-3 styrene chain length, >=30wt%, preferably 40-60wt% middle- chain block polystyrene of 4-20 styrene chain length, <20wt%, preferably <15wt% long-chain block polystyrene of >20 styrene chain length, having >=20wt%, preferably 40-80wt% branched styrene-butadiene copolymer containing tin-carbon bond, and 20-150, preferably 40-80 Mooney viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a styrene-butadiene copolymer rubber containing a branched polymer in which bonded styrene is bonded with a specific chain length and consisting of tin-carbon bonds, and the object thereof is to The object of the present invention is to provide a styrene-pucdiene copolymer rubber having a small hysteresis loss in a vulcanizate and excellent breaking strength.

Conventionally, when obtaining a cystyrene-butadiene copolymer by a solution polymerization method using an organolithium compound as an initiator, the copolymerization reactivity of butadiene in the copolymerization system is greater than that of styrene, so the obtained copolymer is a block polymer. This copolymer has good molding processability, but is not suitable as a tire material because of the large p-hysteresis loss of the vulcanizate.

For this reason, a method of obtaining a random styrene-butadiene copolymer by adding a Lewis base to a solution polymerization system has been proposed.

Furthermore, in recent years, styrene-butadiene copolymers with low hysteresis loss have become desirable due to the demand for lower fuel consumption in automobiles, and methods for reducing the bound styrene content in the copolymers have also been proposed. . However, according to this method, although the hysteresis loss of the vulcanizate is improved, it causes a decrease in the fracture strength, so increasing or decreasing the bound styrene content still affects both the hysteresis loss and fracture strength of the vulcanizate. It was difficult to achieve both.

Recently, ozonolysis-gel permeation chromatography (GPC) has been developed (Po, lyme
r, Vol, 22, 1981, Kuchinaka et al.

p1721-1723), it became possible to know in detail about the chain length distribution of styrene-butadiene copolymers.

The present inventors have conducted extensive studies on the chain length distribution of bonded styrene in styrene-butadiene copolymers using the ozonolysis OPC method. A styrene-butadiene copolymer rubber containing a branched styrene-butadiene copolymer made of tin-carbon bonds is a styrene-butadiene copolymer rubber that has a low hysteresis loss and a high fracture strength. The present invention was achieved by discovering that this is a combination.

That is, the present invention provides a styrene-butadiene copolymer rubber obtained using an organolithium compound as a catalyst, including: 1) 10 to 45% by weight of bound styrene; 11) short styrene chain lengths of 1 to 3 in the bound styrene; Less than 50% by weight of chain polystyrene, 60% by weight or more of medium chain block polystyrene with a styrene chain length of 4 to 20, less than 20% by weight of long chain block polystyrene with a styrene chain length of more than 20, iii) From tin-carbon bonds Branched styrene
at least 20% by weight of butadiene copolymer, iv) Mooney viscosity (ML1+4., I 00°C) of 20 to
150. A styrene-butadiene copolymer rubber characterized by: First, the total bound styrene content of the styrene-butadiene copolymer rubber of the present invention is about 40-60% by weight, preferably about 25-40% by weight.

If the total bound styrene content is less than about 10% by weight, the fracture properties of the vulcanizate will be poor, while if it exceeds about 45% by weight, hysteresis loss will be undesirable. Next, the chain length distribution of bound styrene in the styrene-butadiene copolymer rubber of the present invention can be determined by the ozonolysis GPC method, and short chain polystyrene with a styrene chain length of 1 to 6 is about 50
Less than 25-40% by weight, preferably about 4-2% by weight
The medium chain block polystyrene of o is about 60% by weight or more, preferably about 40 to 60% by weight, and the long chain block polystyrene of more than 20% is less than about 20% by weight, preferably 1
Less than 5% by weight.

When the amount of short chain polystyrene having a styrene chain length of 1 to 6 in the bonded styrene is about 50% by weight or more, the fracture strength and abrasion resistance are sufficiently improved. Moreover, if the medium-chain block polystyrene of 4 to 20 is less than about 30% by weight, the interaction with carbon black is small and the fracture strength and abrasion resistance are not improved. Furthermore, if the long chain block polystyrene exceeding 20 is about 20% by weight or more, the hysteresis loss is large and it is not preferred as a tire tread rubber.

The styrene-butadiene copolymer rubber of the present invention has tin-
At least about 20% by weight of a branched polymer consisting of carbon bonds
, preferably about 40 to 60% by weight, and contains silicon-carbon bonds other than tin and carbon-carbon bonds.
Copolymer rubber containing a branched polymer consisting of carbon bonds cannot be expected to improve hysteresis loss.

Here, the content of the polymer containing tin-carbon bond chains can be easily determined from the high molecular weight component having a bimodal or more molecular weight distribution measured by gel permeation chromatography.

When the tin-carbon bond in the branch is a tin-butadienyl bond rather than a tin-styryl bond, the fracture characteristics and hysteresis loss in the copolymer vulcanizate are improved. Furthermore, if the proportion of the branched polymer consisting of tin-carbon bonds is less than about 20% by weight, the breaking strength and hysteresis loss will not be improved. When the copolymer of the present invention is kneaded with carbon black, stearic acid, zinc white and other compounds by containing the branched polymer in a specific amount (approximately 20% by weight or more), When carbon black is well dispersed, fracture strength is improved and hysteresis loss is reduced.

Further, the Mooney viscosity of the styrene-butadiene copolymer comb of the present invention is in the range of about 20 to 150, preferably about 40 to 80 at ML1+4 100°C. If the Mooney viscosity is less than about 20, the hysteresis loss will be poor, while if it exceeds about 150, the processability will be poor and the carbon black will be poorly dispersed, resulting in poor fracture strength.

The vinyl content of the polybutadiene moiety in the styrene-butadiene copolymer rubber of the present invention is not particularly limited, but is preferably about 12% or more and less than about 50'%.

Copolymer rubbers with a vinyl content of less than about 12% are difficult to manufacture, while at greater than about 50% the fracture and wear properties deteriorate.

The method for producing the styrene-butadiene copolymer rubber of the present invention as described above includes (a) using an organic lithium compound as a catalyst in a hydrocarbon solvent and a Lewis base as necessary;
, 6-butadiene and styrene are added intermittently in several portions to carry out polymerization, and then a coupling reaction is carried out with a tin halide compound.

(b) Another method is to first charge styrene into a hydrocarbon solvent in which an organolithium compound and, if necessary, a Lewis base are present, and then polymerize by sequentially adding 1,3-butadiene, and then convert the styrene into a hydrocarbon solvent. Obtained by coupling with a tin compound.

Examples of the hydrocarbon solvent used for producing the styrene-butadiene copolymer comb include hexane, heptane, cyclohexane, benzene, quinolene, and mixtures thereof. As organolithium compounds,
For example, n-butyllithium, 5ec-butyllithium, alkyllithium such as 1,4-dilithiobutane, alkylene dilithium, etc., 5 parts per 100 parts by weight of monomer.
0.02 to 0.2 parts by weight is used.

Lewis bases used as needed, styrene, butadiene randomizing agents, and at the same time as regulators of the microstructure of the butadiene moiety, such as dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol butyl. Ercil,
Diethylene glycol dimethyl ether, triethylamine, pyridine, N-methylmorpholine, NNN'N'
-Tetramethylethylenediamine, ethers such as 1,2-dimethoxyethane, and 6th class amines.

Examples of the halogenated tin compound used for coupling include tetrachlorotin, tetrabromtin, methyltrichlorotin, butyltrichlorotin, bischlorostannylethane, etc. ...Used in a proportion of 0.2 to 6 equivalents of rogen atoms.

In addition, the polymerization of styrene and 1,3-butadiene is 0 to 1
The coupling reaction between the lithium atom-terminated styrene-butadiene copolymer and the tin halide compound is carried out at 50°C, preferably 30~ioo,"c.
It is carried out at 110°C.

Further, in the present invention, in order to obtain a styrene-butadiene copolymer rubber containing a branched styrene-butadiene copolymer consisting of tin-butadienyl bonds, the above-mentioned manufacturing method (a) is used.
In this case, it is obtained by adding 1 to 50 moles of 1,6-butadiene per atomic equivalent of Li1y of the fabric lithium compound after polymerization, and then carrying out a coupling reaction with a tin halide compound.

Thus, the styrene-butadiene copolymer rubber of the present invention is
Alone or blended with natural rubber, cis-1,4 polyimprene, emulsion polymerized styrene-butadiene copolymer, high cis-1,4 polybutadiene, low cis-1,4 holiftadiene, ethylene propylene diene copolymer, etc. If necessary, it is extended with aromatic, naphthenic, or roughin oil, and then carbon black and other reinforcing agents, fillers, stearic acid, zinc white, antiaging agents, and vulcanization are used. After adding accelerators and vulcanizing agents and other usual vulcanized rubber compounding agents, vulcanization is carried out after molding.
In addition to tire treads, it can be used in a wide variety of applications, including tire components, anti-vibration rubber, belts, hoses, window frames, and industrial supplies.

In particular, the copolymer rubber of the present invention has a completely new styrene chain length, and has properties that were difficult to achieve in the past, such as low hysteresis loss and excellent fracture properties in the vulcanizate. It is especially useful as a tire trend.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples. In addition, various measurements in the examples were as follows.

<Amount of bound styrene> Calibration curve measurement using infrared method based on absorption of phenyl group at 699 cm.

<Microstructure> I used the infrared method (Morello method).

<Ratio of branched polymer> Measured from the ratio of the peak area on the high molecular weight side of the bimodal molecular weight distribution of Gelper 8A chromatograph (GPC).

Tensile strength〉 Constructed in accordance with JIS I6301.

<70"C rebound resilience> Resilience using a Dunlop trypsometer. Measured as an index of hysteresis loss.

Example 1 1250y of cyclohexane was placed in a 10A reactor equipped with a stirrer.
= 1-hexane 1250F, 1,6-butadiene 10
y and 150 y of styrene were charged, and the temperature inside the reactor was set to 7.
After adjusting to 0°C, n-butyllithium 0.605'
was charged to start polymerization. After polymerization was carried out at 70'°C for 5 minutes, 1,6-butadiene 335y was added five times each to effect copolymerization. When adding 1,6-butadiene for the second time and thereafter, it was confirmed that 95% by weight or more of the previously added 1,3-butadiene had been consumed in the copolymerization, and then addition 1 to polymerization were carried out. After that, 1,3-butadiene 5F was further added and polymerized, and then tin tetrachloride o,
Soy was added and the coupling reaction was carried out at 70°C for 30 minutes. 2,6-ditertiary-butyl-p-cresol 5y is added to this polymer solution.

After addition, the solvent was removed by steam stripping and then dried with a hot roll at 110''C to obtain a polymer.

The properties of the copolymer raw rubber are shown in Table 1.

The copolymer was kneaded with a 250CC plastomill and a 6-inch roll according to the formulation shown in Table 2, and then mixed with 14
Vulcanization was performed at 5° C. for 35 minutes.

The properties of the vulcanizate are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that 5 y of tetrahydrofuran was added before the start of polymerization in Example 1. Example 6 1250 y of cyclohexane was added to a 10 t reactor equipped with a stirrer
After charging 125 Dy of n-hexane, 10 parts of 1,3-phytadiene, and 120 parts of styrene and adjusting the temperature inside the reactor to 70°C, 0.60 Dy of n-phyllithium was added.
y was charged to start polymerization.

After polymerization was carried out at 70°C for 5 minutes, 1,6-phytadiene 665F was added 5 times, 11 times each, to carry out copolymerization. When adding 1,3-butadiene for the second and subsequent times, it was confirmed that 95% or more of the previously added 1,3-butadiene had been consumed by copolymerization, and then the addition was carried out.

Thereafter, 1,6-butadiene 5y was further added and polymerized, and then 0.80p of tin tetrachloride was added and a coupling reaction was carried out at 70°C for 30 minutes.

Thereafter, the same procedure as in Example 1 was carried out.

Comparative Example 1 Silicon tetrachloride 0962 was used instead of tin tetrachloride in Example 1.
Styrene was prepared in the same manner as in Example 1 except that
A butadiene copolymer was obtained.

Comparative Example 2 A styrene-butadiene copolymer was obtained in the same manner as in Example 1 except that 0.40 y of n-butyllithium and 0.10 y of tin tetrachloride were used in Example 1.

Comparative Example 10 was added to the reactor and 3.00 CJP of cyclohexane was added.
'Potassium silbenzenesulfonate 002y, 1.3-
Prepare 645y of butadiene and 150y of styrene 1
After adjusting the temperature inside the reactor to 70°C, 0.40F of n-butyllithium was charged to start polymerization. 3 at 70℃
After polymerization for 0 minutes, 5y of 1, filtrate-butadiene was added and reacted at 70°C for 10 minutes, and then 0.8% of tin tetrachloride was added.
y was added and the coupling reaction was carried out at 70°C for 60 minutes. Thereafter, the same procedure as in Example 1 was carried out to form random styrene.
A butadiene copolymer was obtained.

Comparative Example 4 1500y of cyclohexane in a 10t reactor with a stirrer
, n-hexane 1500y, 1,3-butadiene 345y
y and styrene 1507 and the temperature inside the reactor was set to 70.
After adjusting the GK, 0.5 Of of n-butyl lithium was charged and polymerization was carried out at 70°C for 2 hours. 1. Added 5 Y of ro-butadiene and 10 minutes later added 0.80 F of tin tetrachloride.
The coupling reaction was carried out at 70°C for 60 minutes. Thereafter, in the same manner as in Example 1, a styrene-butadiene copolymer containing block polystyrene was obtained.

Comparative Example 5 In Example 1, instead of styrene 150F, 30y, 1.6
- except using 465y instead of butadiene 365g,
The same procedure as in Example 1 was carried out.

Comparative Example 6 In place of styrene 150y in Example 1, 2501.1,
The same procedure as in Example 1 was carried out except that 245y was used in place of 6-butadiene 635y.

qq 2nd Table Weight Parts Polymer 100 HAI" Carbon 5° Stearic Acid 1 Zinc White 3 Vulcanization Accelerator NS" Sulfur 1.75 * n-tert-butyl-2-benzothiazylsulfenamide Patent Applicant Japan Synthetic Rubber Co., Ltd. Bridgestone Tire Co., Ltd. Representative Patent Attorney Shigetaka Shirai Procedural Amendment (Method) % Formula % 1. Indication of the case Patent Application No. 130931 of 1988 2. Name of the invention Styrene-butadiene copolymer rubber 6. Relationship with the case of the person making the amendment Patent applicant address: 2-11-24 Tsukiji, Chuo-ku, Tokyo Name (4)
17) Japan Synthetic Rubber Co., Ltd. Representative: Hisashi Yoshimitsu (and 1 other person) 4. Agent: 107 Address: Room 315, Palais Royal Akasaka, 2-17-54 Akasaka, Minato-ku, Tokyo [Shipping date: October 25, 1988] ] Page 18 of the specification (full text) is amended as attached.

Claims (1)

[Claims] 1. In the styrene-butadiene copolymer rubber obtained using an organolithium compound as a catalyst, 1) the weight ratio of bound styrene is 10 to 45, and 11) the styrene chain length in the bound styrene is 1 to 45% by weight. Less than 50% by weight of short chain polystyrene of No. 3, 30% by weight or more of medium chain block polystyrene with a styrene chain length of 4 to 20, and 20% by weight of long chain block polystyrene with a styrene chain length of more than 20.
111) Branched styrene-butadiene copolymer consisting of tin-carbon bonds is at least 20% by weight, iv) Mooney viscosity (ML1+4, 1oooC) is 2
0 to 150. A styrene-butadiene copolymer rubber. 2. The styrene-butadiene copolymer comb according to claim 1, wherein the tin-carbon bond is a tin-butadienyl bond. 3. The styrene-butadiene combination according to claim 1 or 2, wherein the vinyl content of the polybutadiene moiety is less than 501. Combined rubber.