JPS5924702A - Styrene-butadiene copolymer - Google Patents

Abstract

PURPOSE:To titled copolymer excellent in abrasion resistance, breaking strength, hysteresis loss, etc., containing a specified branched copolymer in which the bond of the branched portion comprises a tin-butadienyl bond and having a butadiene portion of a low vinyl content. CONSTITUTION:A branched styrene/butadiene copolymer, in which the bonded styrene content is 3-40wt%, the vinyl bond content in the butadiene portion is below 3wt%, and the proportion of a copolymer having a branched portion comprising tin-butadienyl bonds is greater than 20wt%, is obtained by copolymerizing 1,3-butadiene with styrene in a hydrocarbon solvent in the presence of an initiator hich is an organolithium compound (e.g., n-butyllithium), and then reacting the resulting butadienyllithium-terminated copolymer with a tin halide compound (e.g., tin tetrachloride).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a styrene-butadiene copolymer containing a branched polymer in which the bonds of the branched moieties are linked by tin-butadienyl bonds, and the vinyl content of the butadiene moiety is low.

With the demand for lower fuel consumption for automobiles, there has been a strong desire for materials with low hysteresis loss as rubber for tire materials. Therefore, rubbers such as natural rubber, cis 1,4 polyisoprene, and low cis 1.4 or high cis 1.4 polybutadiene have come to be widely used as rubber materials with low hysteresis loss.
Styrene-butadiene copolymers are still used as rubber materials for tires because of problems in terms of breaking strength and the like.

Conventionally, styrene-butadiene copolymers include styrene-butadiene copolymers obtained by emulsion polymerization and styrene-butadiene copolymers using organolithium compounds as initiators, but they have high hysteresis loss and are therefore not suitable for tire rubber materials. The usage rate was limited. For this reason, a styrene-butadiene copolymer with low hysteresis loss has been desired.

Recently, styrene has significantly improved hysteresis loss.
As a butadiene copolymer, a branched styrene-butadiene copolymer in which the bond at the branch portion is a tin-butadienyl bond is known, as described in JP-A-57-55912.

However, these copolymers are essentially random styrene-butadiene copolymers obtained by polymerizing in the presence of ether or tertiary amine using an organolithium compound as an initiator to reduce hysteresis loss. , a copolymer in which the vinyl content of the butadiene moiety exceeds 50%.

Therefore, properties such as wear resistance and breaking strength are not necessarily sufficient. As a result of intensive studies on styrene-butadiene copolymers with excellent wear resistance, fracture strength, and hysteresis loss, the present inventors found that 1,3-butadiene and styrene were used in a hydrocarbon solvent using an organolithium compound as an initiator. Styrene-butadiene containing a branched styrene-butadiene copolymer obtained by the reaction of a styrene-butadiene copolymer with butadienyl lithium terminals and a tin halide compound. In the copolymer, (1) the bound styrene content of the copolymer is 3 to 40% by weight, (11) the vinyl bond content of the butadiene moiety of the copolymer is less than 30%, and 011) the bonding of the branched portion. It has been found that a random styrene-butadiene copolymer 2, characterized in that is tin-butadienyl bonds and the proportion of al-branched styrene-butadiene copolymer is at least 20% by weight, also achieves the objective.

It is important that the copolymer of the present invention contains at least 20% by weight of a branched styrene-butadiene copolymer whose branched moieties are tin-butadienyl bonds, which are specific metal-carbon bonds.

If the proportion of the branched styrene-butadiene copolymer is less than 20% by weight, the hysteresis loss, fracture properties, and abrasion resistance of the vulcanizate will not be sufficiently improved.

Furthermore, in the presence of an ether compound, 1
．． After copolymerizing 3-butadiene and styrene, 1
．． A mustyrene-butadiene copolymer containing a branched styrene-butadiene copolymer in which the bond of the branched portion is a tin-styryl bond obtained by reaction with a tin halide compound without adding 3-butadiene, the bond of the branched portion is Styrene-butadiene copolymers containing branched styrene-butadiene copolymers with silicon-carbon bonds or other carbon-carbon bonds do not sufficiently improve the hysteresis loss of the vulcanizate.

The bound styrene content of the styrene-butadiene copolymer of the present invention is 3 to 40% by weight, preferably 10 to 30% by weight, and 3 to 40% by weight, preferably 10 to 30% by weight.
If it is less than 40% by weight, the fracture properties of the vulcanizate will be poor, and if it exceeds 40% by weight, the hysteresis loss of the vulcanizate will be poor, which is not preferable.

In addition, the random styrene-butadiene copolymer of the present invention means that bound styrene is present in the copolymer with 1, M, Kolth
The oxidative decomposition method of Off et al. [J, Polymer Sel.

Vol. 1, page 429 (1946)), the content of blocked polystyrene in the bound styrene is 10% by weight or less, preferably 5% by weight or less. If the block polystyrene content is less than 10% by weight, the bound styrene may increase or decrease by forming molecular chains. If the block polystyrene content exceeds 10% by weight, the hysteresis loss of the vulcanizate will be poor. Undesirable.

The vinyl bound gold content of the butadiene portion of the copolymer of the invention is less than 30%, preferably less than 20%. If the vinyl content exceeds 30%, the wear resistance and fracture strength of the vulcanizate will deteriorate.
This is not preferable because it results in poor low-temperature properties. .

The Mouni viscosity of the styrene-butadiene copolymer of the present invention is 20-120. When the Mooney viscosity is less than 20, the hysteresis loss of the vulcanizate is large, and when the Mooney viscosity is less than 12.
If it is 0 or more, the processability is poor and undesirable.

The styrene-butadiene copolymer of the present invention is produced by the method described below.

When carrying out a copolymerization reaction of styrene and 1,3-butadiene using an organolithium compound as an initiator in a hydrocarbon solvent, British Patent No. 994726 and Japanese Patent Application Laid-Open No. 143209-1989
As described in 1, 1,3-butadiene and styrene are continuously or semi-continuously mixed so that the amount of styrene in the polymerization system is within a certain range because the copolymerization reactivity of styrene is small. After carrying out the polymerization by adding stepwise or stepwise, finally 0.5 to 100 mol, preferably 1 to 100 mol, per 1 gram atom equivalent of lithium of the organolithium initiator
By adding 50 moles of 1,3-butadiene to form an active butadienyl-lithium-terminated styrene-butadiene copolymer, and reacting this copolymer with a tin halide compound, branched styrene-butadiene is produced. A random styrene-butadiene copolymer containing copolymer is obtained.

Still another method is to carry out a copolymerization reaction of styrene and 1,3-butadiene in a hydrocarbon solvent using an organolithium compound as an initiator, as described in Japanese Patent Publication No. 38-2394. After carrying out the polymerization by adding 1,3-butadiene and styrene at a slow rate, from 0.5 to 1 gram atom equivalent of lithium in the organolithium initiator.
By reacting an active butadienyl-lithium-terminated styrene-butadiene copolymer produced by adding 100 moles, preferably 1 to 50 moles of 1,3-butadiene, with a tin halide compound, branched styrene can be produced. A random styrene-butadiene copolymer containing -butadiene copolymer is obtained.

Tetrahydrofuran, dimethoxybenzene, ethylene glycol dimethyl ether, ethylene glycol diptyl ether, dibutyl ether, triethylamine, pyridine, NNN'N'- Ethers such as tetramethylamine and tertiary amines can be added to improve polymerization activity and randomness of styrene.

Additionally, potassium salts of alcohols, phenols, organic carboxylic acids, and organic sulfonic acids can also be used to improve the randomness of styrene.

1,3-butadiene used in the above polymerization is 1,2-
Butadiene 500 ppm or less, preferably 1100p
p or less is used. The polymerization is carried out under isothermal or temperature-programmed polymerization conditions in the range of 0 to 120°C.

Hydrocarbon solvents used in the polymerization include hexane, heptane, cyclohexanebenzene, xylene, methylcyclopentane, and mixtures thereof. As the organic lithium compound, n-butyllithium, 5eC-butyllithium, tert-butyllithium, propyllithium, phenyllithium, etc. are used. The amount of organolithium compound is 0.02 to 0.2 per 100 parts by weight of monomer.
Used in parts by weight. The amount of 1,3-butadiene added at the final stage of polymerization is 0.00% in 100 parts by weight of total monomers.
It is used in a wide range of 2 to 40 parts by weight.

Examples of tin halide compounds used in the production of branched styrene-butadiene copolymer, that is, in the coupling reaction, include tetrachlorotin, tetrabromtin, methyltrichlorotin, butyltrichlorotin, dichlorotin, bistrichlorostannylethane, and histrichlorotin. Stannyl butane etc. are used, and 0.2 to 3 halogen atoms of the tin halide compound are used per equivalent of the terminal lithium atom of the polymer.
Used in equivalent proportions. Coupling reaction is 50-1
It is carried out at a temperature in the range of 20°C.

The styrene-butadiene copolymer of the present invention can be used alone or in natural rubber, cis 1,4 polyisoprene, emulsion polymerized styrene-butadiene copolymer, solution polymerized styrene-butadiene copolymer, high cis 1.4 polybutadiene, low cis 1 ,4
It is used by blending one or more of polybutadiene and ethylene propylene diene copolymers, and if necessary, it is oil-extended, and ordinary compounding agents for vulcanized rubber are added, and vulcanization is performed to create treads, sidewalls, and beads. It can be used for parts such as tires, anti-vibration rubber, belts, hoses, window frames, and other industrial products.

The styrene-butadiene copolymer of the present invention can also be used as a pace rubber for impact-resistant polystyrene, impact-resistant resins made of acrylonitrile/styrene/rubber, and the like.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the scope of the invention unless it goes beyond the gist of the invention.

In addition, various measurements were performed according to the following methods.

The tensile properties were measured according to JIS K6301.

As an index of hysteresis loss, rebound resilience at 70° C. (resilience measured by Dunlop trypsometer) was used.

Abrasion resistance was measured using a Pico abrasion tester.

The microstructure of the butadiene moiety of the styrene-butadiene copolymer was determined by an infrared method (Morello method). The content of bound styrene was determined from a calibration curve using an infrared method based on the absorption of phenyl groups of 699crrL-1.

The proportion of the branched styrene-butadiene copolymer in the styrene-butadiene copolymer was determined from the ratio of the area of the peak on the high molecular weight side of gel permeation chromatography (GPO) to the total peak area. The proportion of blocked boris-styrene to the total styrene content in the styrene-butadiene copolymer was determined by the method of I-M-Kolthoff et al. mentioned above.

Example 1 Reactor C with a stirrer of 10/cyclohexane 1250
11, n-hexane 1250#, 1,3-butadiene 4
5g of styrene 5519 was charged, and the temperature inside the reactor was set to 60.
After adjusting the temperature to .degree. C., 0.34 # of n-butyllithium was charged to start polymerization. After polymerization at 60°C for 10 minutes, 1,3-butadiene 2801i+ and styrene 70.9
A mixture of 1.3-butadiene 50F was continuously fed into the reactor at a rate of 10 g/min and the process was carried out at 60°C for 35 minutes. Next, 1,3-butadiene 50F was continuously fed into the reactor at a rate of 5 g/min. Polymerization was carried out at 60° C. for 10 minutes while supplying the solution.

Thereafter, 0.175.9% of tin tetrachloride was added and a coupling reaction was carried out at 60°C for 30 minutes. 2.6 in polymer solution
After adding 2.5 g of -ditertiary-butyl-p-cresol, the solvent was removed by steam stripping and then dried with a heated roll at 110°C to obtain a copolymer. Properties 9 of the copolymer raw rubber are shown in Table 1.

The copolymer was kneaded and blended using a '250 country plastomill and a 6-inch roll according to the formulation shown in Table 2, and then
Vulcanization was carried out at ℃ 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 2 g of tetrahydrofuran was added before starting the polymerization.

Example 3 Cyclohexane 1250.
9. n''-hexane 1250.9, 65 g of 1,3-butadiene and 35 g of styrene were charged, and the temperature inside the reactor was set to 60.
After adjusting the temperature to .degree. C., 0.351 I of n-butyllithium was charged to start polymerization.

After polymerization was carried out at 60°C for 10 minutes, a mixture of 335 g of 1.3-butadiene and 15.9 g of styrene was continuously fed to the reactor at a rate of 109/min, and polymerization was carried out at 60°C for 35 minutes. . Next, 1,3-butadiene 5011 was continuously fed into the reactor at a rate of 5 g/min at 60°C.
Polymerization was carried out for minutes. Then tin tetrachloride 0.1751
9 was added and the coupling reaction was carried out at 60'°C for 30 minutes.

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

Example 4 Cyclohexane 1250.
9, n-hexane 1250g, 1,3-butadiene 30
After charging 70 g of styrene and adjusting the temperature inside the reactor to 60° C., 0.33 g of n-butyllithium was charged to start polymerization.

After polymerization was carried out at 60°C for 10 minutes, a mixture of 270 g of 1,3-butadiene and 80 g of styrene was continuously fed into the reactor at a rate of 10 g/min, and polymerization was carried out at 60°C for 35 minutes. Next, while 50 g of 1,3-butadiene was continuously fed into the reactor at a rate of 5 g/min, polymerization was carried out for 60 DEG CIO minutes. Thereafter, 0.1"75 g of tin tetrachloride was added and a coupling reaction was carried out at 60°C for 30 minutes.

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

Comparative Example 1 A styrene-butadiene copolymer containing a branched polymer with a vinyl content of 50% in the butadiene moiety was obtained in the same manner as in Example 1 except that 8 g of tetrahydrofuran was added before the start of polymerization. .

Comparative Example 2 1250 g of cyclohexane in a reactor with a 10/1 stirrer
, n-hexane 1250, 9.1,3-butadiene 75
After charging 25g of styrene and adjusting the temperature inside the reactor to 60°C, 0.35g of n-butyllithium was charged,
Polymerization started.

After polymerization was carried out at 60°C for 10 minutes, a mixture of 262.5.9 1,3-butadiene and 87.5F styrene was continuously fed into the reactor at a rate of 10 g/min.
Polymerization was carried out for 5 minutes. Next, 1,3-butadiene 37.
5&, 12.5g of styrene was charged into the reactor, and 60'
Polymerization was carried out for 10 minutes.

Thereafter, 0.180 g of tin tetrachloride was added, and a coupling reaction was carried out at 60° C. for 30 minutes. Thereafter, the same procedure as in Example 1 was carried out to obtain a styrene-butadiene copolymer containing a branched polymer in which the bond at the branched portion was a tin-styryl bond.

Comparative Example 3 Cyclohexane 1250.
9. n-hexane 1250,9. ．． After charging 100 g of 1,3-butadiene and adjusting the temperature inside the reactor to 60° C., 0.34 g of n-butyllithium was charged to start polymerization.

After polymerization was carried out at 60°C for 10 minutes, 350 g of 1,3-butadiene was continuously supplied to the reactor at a rate of 10 g/min, and polymerization was carried out at 60°C for 35 minutes. Next 1.3
-50 g of butadiene was charged into a reactor and polymerization was carried out at 60°C for 10 minutes. Thereafter, 0.175 g of tin tetrachloride was added, and a coupling reaction was carried out at 60°C for 30 minutes.

Thereafter, the same procedure as in Example 1 was carried out to obtain polybutadiene containing a branched polymer.

Comparative Example 4 1250 g of cyclohexane in a 101 reactor equipped with a stirrer
, n-hexane 1250g, 1,3-butadiene 15g
After charging 85 g of styrene and adjusting the temperature inside the reactor to 60°C, 0.35 g of n-butyllithium was added. ! 7 was charged and polymerization was started.

After polymerization was carried out at 60°C for 10 minutes, a mixture of 210 g of 1,3-butadiene and 140 g of styrene was continuously supplied to the reactor at a rate of 1019/min, and polymerization was carried out at 60°C for 35 minutes. Next, 50 g of 1,3-butadiene was charged into the reactor, and polymerization was carried out at 60° C. for 10 minutes. Thereafter, 0.175 g of tin tetrachloride was added, and a coupling reaction was carried out at 60° C. for 30 minutes.

Thereafter, the same procedure as in Example 1 was carried out to obtain 45% bonded styrene.
A styrene-butadiene copolymer containing % by weight of branched polymer was obtained.

Comparative Example 5 2000 g of cyclohexane was placed in a reactor equipped with a 101 stirrer.
, n-hexane 2000g, 1,3-butadiene 375
g, 125g of styrene was charged, and the temperature inside the reactor was set to 60℃.
After adjusting the temperature, 0.36 g of n-butyllithium was added and polymerization was carried out at 60° C. for 60 minutes. Thereafter, 0.180 g of tin tetrachloride was added and a coupling reaction was carried out at 60° C. for 30 minutes.

Thereafter, the same procedure as in Example 1 was carried out to obtain a styrene-butadiene copolymer containing block polystyrene.

Comparative Example 6 The same procedure as in Example 1 was carried out except that 0.32191% of monobutyllithium and 0.025.9% of tin tetrachloride were used.

The styrene-butadiene copolymer vulcanizates of Examples 1 to 4 have excellent and well-balanced tensile strength, 70° C. impact resilience, and abrasion resistance.

The vulcanized product of the polymer of Comparative Example 1 is inferior in wear resistance.

The vulcanized product of the polymer of Comparative Example 2 has a tensile strength of 70°C because it is a branched polymer in which the bond at the branched portion is a tin-styryl bond.
Inferior in rebound resilience.

Since the vulcanized product of the polymer of Comparative Example 3 has zero bound styrene, it has excellent 70°C impact resilience but is inferior in tensile strength.

The vulcanizate of the polymer of Comparative Example 4 contained 45% by weight of bound styrene.
Therefore, it is inferior in terms of rebound resilience at 70°C.

In the vulcanizate of the polymer of Comparative Example 6, the proportion of branched polymer was 20.
% or less, it is inferior in terms of 70°C rebound resilience and tensile strength.

μi bunro type 5 #1 ir, 7704＾glue I↓gb
゛ / 7 Sheath 4 and y1 N meeting '70' (-Gobee 4.1 main, tljij arc (Shizuku, attached, 1, 5 Ko 2nd
Volume by surface weight - 100HAF carbon 50 Stearic acid 1 Zinc Flower 3 Vulcanization accelerator N
8* 1 I Ou 1
．． 75* n-tert-butyl-2-benzothiazylsulfenamide patent field Japan Synthetic Rubber Co., Ltd. Brideston Tire Co., Ltd. Patent attorney Akira Ito Procedural amendment (method) % formula % 1. Indication of the case 1982 Patent Specification No. 1329912, name of the invention: Styrene-butanene copolymer 6, relationship with the case of the person making the amendment Patent applicant address: 2-11-24 Tsukiji, Chuo-ku, Tokyo Name:
Japan Synthetic Rubber Co., Ltd. Representative Hisashi Yoshimitsu 4th generation Masato 101 Address 2-42 Kanda Jimbocho, Chiyoda-ku, Tokyo October 7, 1981 (Delivery date October 26, 1980)
6. Specification subject to amendment (reduction of ballpoint pen writing in table frame) Contents of Z amendment as shown in the attached sheet

Claims (1)

[Claims] Polymer obtained in a hydrocarbon solvent using an organolithium compound as an initiator.Styrene-terminated butadienyllithium
In a styrene-butadiene copolymer containing a styrene-butadiene copolymer obtained by reacting a butadiene copolymer with a halo, tin-genide compound, (1) the bound styrene content of the copolymer is (11) the vinyl bond content of the butadiene moiety of the copolymer is less than 30%; Random styrene-butadiene copolymer, characterized in that the proportion of polymer is at least 20% by weight.