JPS63243116A - Production of styrene butadiene copolymer - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer having excellent friction characteristics and repulsion characteristics after vulcanization, by copolymerizing styrene with,3-butadiene in a hydrocarbon in the presence of specific amounts of an organo-potassium salt and an allene compound by the use of an organo-lithium initiator in a stepwise way. CONSTITUTION:In polymerizing 10-50pts.wt. styrene with 90-50pts.wt. 1,3-butadiene in a hydrocarbon solvent by the use of an organo-lithium initiator, 0.01-0.5mol. based on 1 gram atom lithium of the organolithium initiator of an organopotassium salt (e.g. potassium phenoxide) and 0.1-1.5mol. based on the same amount of an allene compound (e.g. 1,2-butadiene), a monomer mixture consisting of consisting of 60-98wt.% based on sum of 1,3-butadiene and 70-100 based on sum of styrene is initially polymerized. When the polymerization conversion ratio reaches 90-99.5%, the residual monomers are continuously or intermittently added to the polymerization system more than 1-2 times to give the aimed copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Application Field The present invention relates to a method for producing a styrene-butadiene copolymer, more specifically a copolymer with a vinyl content of 30% that has good wear properties and repulsion properties after vulcanization. The present invention relates to the following method for producing a random styrene-butadiene copolymer.

b. Conventional technology Styrene-butadiene copolymer in which styrene and butadiene units are randomly distributed in the polymer chain (hereinafter referred to as random styrene-butadiene copolymer)
is obtained using a lithium-based polymerization initiator and is used in various rubber products including tires.

Conventionally, as a method for obtaining this random styrene-butadiene copolymer, when styrene and 1,3-butadiene are copolymerized using a lithium-based polymerization initiator, a copolymerization reaction of styrene and 1,3-butadiene is carried out. Due to the large difference in sex ratio, the
No. 68, etc., proposes a method in which 1,3-butadiene is added from the side of the reactor using a reactor equipped with a specific stirring device. Further, in Japanese Patent Publication No. 49-48188, British Patent No. 903331, British Patent No. 994726, etc., 1,3-butadiene or 1. A method of adjusting the amounts of 3-butadiene and styrene added has been proposed.

However, these methods require complex reactors and
Furthermore, since it is necessary to strictly control the composition ratio of styrene and 1,3-butadiene in the polymerization system, the reaction operation becomes complicated. In other words, if the balance between the consumption rate of the monomers 1,3-butadiene and styrene in the polymerization reaction and the amounts of 1,3-butadiene or 1,3-butadiene and styrene added is out of balance, the resulting polymer will become block-shaped. Since the vulcanizate contains a polystyrene component, its rebound properties and abrasion properties are reduced, making it undesirable as a tire rubber. - It is necessary to closely control the composition ratio of butadiene.

Therefore, as a method for easily obtaining a random styrene-butadiene copolymer with a vinyl content of 30% or less in the polybutadiene moiety, Japanese Patent Publication No. 44-20463 and Japanese Patent Publication No. 45-
No. 22338, Japanese Patent Publication No. 54-44315, etc. have been proposed. In these methods, alkali metal alkoxides, alkali metal phenoxytes, alkali metal sulfonates, alkali metal carboxylic acids are used together with an organolithium initiator. Salt etc. are used. However, in this method, as shown in Japanese Patent Publication No. 60-55527, if arenes such as 1,2-butadiene and allene, which are used to prevent gel formation and reduce molecular weight, are present, styrene and 1. Since the randomness of the copolymerization reaction of 3-butadiene is inhibited, the incompletely random styrene
A butadiene copolymer is obtained.

In Japanese Patent Publication No. 60-'55527, an incompletely random styrene-butadiene copolymer obtained by polymerizing butyllithium as a polymerization initiator in the presence of 1,2-butadiene/potassium dodecylbenzenesulfonate is It is disclosed that sulfur has excellent wear resistance and heat generation properties.

As a result of further study on the above method, the present inventors found that
When attempting to obtain a styrene-butadiene copolymer with a bound styrene content of 20% or more by this method, 1.3-
When the polymerization conversion rate of butadiene exceeds 95%, the amount of long-chain block polystyrene in which nine or more styrene molecules are continuously bonded in the polymer molecular chain increases significantly, resulting in a decrease in the repulsion properties of the vulcanizate. I found out.

Furthermore, with this method, it is difficult to obtain a so-called completely random copolymer in which the bonded styrenes in the polymer molecular chain are randomly arranged.

Problems to be Solved by the C0 Invention The present invention has been made in view of the above points, and eliminates the need to strictly control the composition ratio of 1,3-butadiene and styrene in the polymerization system, and prevents gelling. Even in the presence of allene compounds that act as agents and molecular weight modifiers, randomness is not inhibited even at high styrene contents, and the vulcanizate has excellent abrasion resistance, rebound properties, tensile properties, and tear strength. The present invention provides a method for producing a styrene-butadiene copolymer with random content.

d. Means and effects for solving the problems, that is, the present invention provides 10 to 50 parts by weight of styrene and 90 to 50 parts by weight of 1,3-butadiene in a hydrocarbon solvent, an organolithium initiator, an organolithium initiator, and an organolithium initiator. In copolymerization using 0.01 to 0.5 mol of an organopotassium salt per gram atom equivalent of lithium as an initiator and 0.1 to 1.5 mol of an allene compound per gram atomic equivalent of lithium as an organolithium initiator. , i) 60 to 9 of the total amount of 1,3-butadiene used in polymerization
ii) When the polymerization conversion rate of 1,3-butadiene in the polymerization system reaches 90 to 99.5%, the remaining 1 .3-Butadiene or C3-butadiene and styrene are added to the polymerization system once or twice or more continuously or intermittently to perform the polymerization. be.

The hydrocarbon solvent used in the present invention is one or more selected from hydrocarbon compounds such as benzene, toluene, xylene, hexane, heptane, octane, cyclohexane, methylcyclopenkune, methylbutene, and isopentane. The amount used is 50 to 1000 parts by weight per 100 parts by weight of monomer.

As the organolithium polymerization initiator, propyllithium,
n-butyllithium, 5ec-butyllithium, ter
Examples include t-butyllithium, phenyllithium, 1,4-dilithiobutane, (1), 2-dilithio-1,2-phenylethane, and preferably n-butyllithium and 5ec-butyllithium are used.

The amount of the organolithium polymerization initiator to be used is appropriately determined depending on the required Mooney viscosity (ML ++ 4. to ℃) or molecular weight of the produced polymer, but the Mooney viscosity of the produced polymer (MLI + 4.1 ℃ to ℃) is determined as appropriate. 20 to 200, 0.1 to 20 mmol per 100 g of monomer,
It is preferably used in a range of 0.3 to 10 mmol.

As the organic potassium salt, potassium alkoxide, potassium phenoxide, potassium salt of organic carboxylic acid, potassium salt of organic sulfonic acid, potassium salt of organic phosphoric acid, etc. are used.

Examples of potassium alkoxide and potassium phenoxide include potassium isopropoxide and potassium tert.
-butoxide, potassium 2-methylpropoxide, potassium 1,1-dimethylpropoxide, potassium n-hebutaoxide, potassium cyclohexaoxide, potassium benzyloxide, potassium 2-ethyl-1-hexoxide, potassium 2-octaoxide, Potassium-2-bebutaoxide, potassium phenoxide, potassium 2,6-
Sheet tert-butyl-p-methyl phenoxide, potassium octyl phenoxide, potassium nonyl phenoxide, potassium dodecyl phenoxide and these potassium alkoxides, potassium phenoxide and carbon atoms 1 to 1
Examples include complexes of aliphatic and alicyclic alcohols, thioalcohols, primary amines, and secondary amines.

Potassium salts of organic carboxylic acids include isovaleric acid, caprylic acid, lauric acid, palmitic acid, stearic acid, oleic acid, riluic acid, benzoic acid, phthalic acid,
Examples include potassium salts such as 2-ethylhexanoic acid.

Also included are complexes of these organic carboxylic acids with aliphatic or alicyclic alcohols having 1 to 12 carbon atoms, thioalcohols, primary amines, secondary amines, and the like.

In addition, examples of potassium salts of organic sulfonic acids include dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid,
Examples include potassium salts of organic sulfonic acids such as hexadecylbenzenesulfonic acid and octadecylbenzenesulfonic acid. Also included are complexes of potassium salts of these organic sulfonic acids and aliphatic or alicyclic alcohols having 1 to 12 carbon atoms, thioalcohols, primary amines, secondary amines, and the like.

These organic potassium salts are used in an amount of 0.01 to 0.5 mol per gram atom equivalent of lithium in the organolithium initiator. If the amount is less than 0.01 mol, it is difficult to obtain a random styrene-butadiene copolymer;
If the amount exceeds 5 moles, the polymerization activity will decrease or it will be difficult to obtain a high molecular weight polymer for oil-extended rubber.

Furthermore, if necessary, diethyl ether, di-n-butyl ether, ethylene glycol diethyl ether, ethylene glycol, cold dibutyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, α-methoxytetrahydrofuran, 0-dimethoxybenzenepyridine, tetramethylethylenediamine, dipiperidine Polar compounds such as ethers such as noethane and tertiary amines can also be used in combination with organic potassium salts as long as the vinyl content of the polybutadiene moiety of the styrene-butadiene copolymer is 30% or less. At amounts of polar compounds such that the vinyl content is less than 30%, a random styrene-butadiene copolymer cannot be obtained. Also, the vinyl content is 30
% of styrene-butadiene copolymer, it is possible to obtain a random styrene-butadiene copolymer using only a polar compound without using an organic potassium salt. It is not possible to obtain a styrene-butadiene copolymer with excellent properties and rebound properties.

Allene compounds have the ability to prevent gel formation during polymer production and act as molecular weight regulators.
Examples include 1,2-butadiene, ethyl arene, dimethyl arene, etc., but 1,2-butadiene is preferably used.

The amount used is in the range of 0.1 to 1.5 mol per gram atom equivalent of lithium as the organolithium polymerization initiator.

If the amount is less than 0.1 mol, gel formation cannot be prevented during continuous polymerization at high temperatures of 70° C. or higher. Also 1
If the amount exceeds 5 moles, the polymerization activity and randomness will decrease significantly, which is not preferable.

In the present invention, in order to obtain a random styrene-butadiene copolymer, there is an allene compound that acts to prevent gel formation or as a molecular weight regulator, so using only an organic potassium compound will not yield a random styrene-butadiene copolymer. That is difficult.

Even if a random styrene-butadiene copolymer is obtained by using a large amount of potassium salt, the molecular weight (Mooney viscosity) may decrease significantly or the copolymer may contain a large amount of gel, resulting in a vulcanized product. It is unfavorable in terms of tensile properties, tear strength, rebound properties, abrasion resistance, etc. Therefore, in order to solve these problems, the monomers to be used are added to the polymerization system in two or more steps, and different 1,
Polymerization is carried out by adding a monomer mixture having a composition ratio of 3-butadiene and styrene. That is, in the first stage, the copolymerization reaction is carried out at 60 to 90% of the total amount of 1,3-butadiene used.
% and 70 to 100% of the total amount of styrene, and organic lithium polymerization is applied to a mixture of styrene and 1,3-butadiene with a styrene content equivalent to or higher than the bound styrene content of the final copolymer. Polymerization is initiated by adding an initiator, an organic potassium salt and an allene compound. In this first stage polymerization, it is preferred to use 50 to 98% of the total amount of all monomers used in the first and second stages. This amount is 50%
If it is less than 98%, the amount of deactivated polymer will increase during the second and subsequent polymerization due to impurities contained in the monomer, and if it is more than 98%, the monomer added later will prevent the formation of block polystyrene. less effective.

When starting the first-stage polymerization reaction, the amount of styrene in the monomer mixture charged into the polymerization system can be adjusted to be equal to or higher than the bound styrene content in the final copolymer. The amount of styrene incorporated into the polymer can be increased and the distribution of styrene within the polymer molecular chain can be made uniform.

At this time, styrene and 1
, 3-butadiene, the content of bound styrene in the desired polymer, the potassium/lithium ratio to be added,
Since it changes depending on the polymerization conditions such as the allene/lithium ratio, it is necessary to appropriately select the optimum composition ratio. - As an example, the composition ratio of styrene and 1,3-butadiene is in the range of 1/9 to 2/1.

The polymerization temperature of the polymerization reaction is usually 30 to 130°C, preferably 50 to 120°C. When the polymerization temperature is less than 30°C, the polymerization rate is extremely slow, and when the polymerization temperature exceeds 130°C, the polymerization rate is extremely fast. Control the polymerization conversion rate of 1,3-butadiene in the range of 90 to 99.5%. becomes difficult.

Next, when the polymerization conversion rate of 1,3-butadiene in the polymerization system is 90 to 99.5%, the second stage monomer is added. Within this range of polymerization conversion of 1,3-butadiene, the polymerization reaction is at a stage where almost no styrene block polymer to be copolymerized is produced, and when this polymerization conversion exceeds 99.5%, styrene block polymers are formed. This is not preferable because the polymer content increases rapidly and the repulsion properties or heat generation properties of the vulcanizate of the styrene-butadiene copolymer ultimately obtained deteriorate.

The amount of monomer added in the second stage is the remainder of the monomer used in the first stage, and is 1,3-butadiene or 1,3-butadiene.
Sometimes it is both butadiene and styrene. These monomers can be added once or twice or more, or can be added continuously at a constant rate from a predetermined time into the polymerization system. The polymerization temperature in the second stage is 30-13
It is carried out at 0°C, preferably 70-120°C. 30℃
If it is less than 130° C., the polymerization temperature is extremely slow, and if it exceeds 130° C., gel is likely to be formed in continuous polymerization, which is not preferable.

The polymerization method carried out in the first stage and the second stage may be a batch polymerization method or a continuous polymerization method.

The batch polymerization method is suitable for obtaining a polymer with a narrow molecular weight distribution, and the continuous polymerization method is suitable for obtaining a polymer with a wide molecular weight distribution. Even in batch polymerization, by using a polyfunctional coupling agent during or after polymerization, the molecular weight distribution of the resulting copolymer can be widened.

After the second stage of polymerization, the polymerization reaction may be terminated using a polymerization terminator selected from water, alcohols, phenols, organic carboxylic acids, and the like.

In addition, in order to widen the molecular weight distribution and further improve the anti-In properties and wear resistance of the vulcanizate, alkenyl aromatic compounds such as divinylbenzene and diisopropenylbenzene, tin tetrachloride, dibutyltin dichloride,
Tin halide compounds such as tributyltin chloride and triphenyltin chloride, silicon halide compounds such as silicon tetrachloride, butyltrichlorosilicon, and methyltrichlorosilicon, phenyl isocyanate, 2.4
- tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric type diphenylmethane diisocyanate,
Isocyanate compounds such as isophorone diisocyanate and hexamethylene diisocyanate, N, N'-
Dimethylaminobenzophenone, N,N'-diethylaminobenzophenone, N-dimethylaminobenzaldehyde, N-diethylaminobenzaldehyde, N-
Dimethylaminobenzoyl chloride, methyl ester of N-dimethylaminobenzoic acid, p-diethylaminostyrene, p-dimethylaminostyrene, p-dimethylaminomethylstyrene, 1-[N-dimethylaminoco-4
- dialkylamino-substituted aromatic compounds such as chlorobenzene, aromatic heteronitrogen-containing compounds such as 4-vinylpyridine, 2-vinylpyridine, bis(2-pyridyl)ketone, bis(4-pyridyl)ketone, 1,3-diethyl −
One or more cyclic urea compounds such as 2-imidazolidinone and 1,3-dimethyl-2-imidazolidinone are selected and added to the polymerization system to terminate active polymer terminals. You can also do it.

The styrene-butadiene copolymer of the present invention is a random copolymer with a bound styrene content of 10 to 50% by weight and a block polystyrene content of less than 2.0% in the bound styrene. The block polystyrene content is 1. M
, in the method of olthoff (J, Polymer Sc
i, Vol. 1429 (1946)).

The polymerization reaction solution containing the styrene-butadiene copolymer obtained by the method of the present invention is prepared by a method used in a normal solution polymerization method, for example, by adding a stabilizer etc. in a solution state, and then adding naphthene as necessary. The target styrene-butadiene copolymer can be obtained by adding oil or highly aromatic oil, separating the rubber and solvent by direct drying or steam stripping, washing, and drying.

The styrene-butadiene copolymer of the present invention can be used alone or blended with natural rubber, polyisoprene rubber, emulsion polymerized styrene-butadiene rubber, polybutadiene, etc., and can be used in rolls, pans, etc., and reinforcing agents such as carbon black or silica, and various compounding agents. After kneading with a burr mixer,
It is vulcanized by adding sulfur, a vulcanization accelerator, etc., and used for tire rubber such as treads, sidewalls, and carcass, as well as belts, vibration-proof rubber, and other industrial products.

e. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples, but these Examples are not intended to limit the scope of the present invention.

Example 1 A first tank reactor having an internal volume of 101 and having a ribbon stirrer was charged with 1.3-butadiene containing 300 ppm of 1.2-butadiene.
Butadiene 1.95kg/hr, styrene 0.75k
g/hr, cyclohexane 13.5kg/hr Sn
-Butyllithium 1.20g/hr.

A complex of 2-ethylhexanol and potassium nonyl phenoxide was continuously supplied at a rate of 0.485 g/hr.
Polymerization was carried out at ℃. At the outlet of the first reactor, 300 p of 1,2-butadiene is added to the outflowing reaction solution.
Continuously feed 1,3-butadiene containing PM at 0.30 kg/hr, and transfer it to a second reactor of the same size as the first reactor.
The polymer was introduced into a reactor and further polymerized at 100°C.

At the outlet of the second reactor, 2,6-tert-butylcresol is added to the polymer 1 in the outflowing polymerization solution.
Polymerization was stopped by adding 0.4 parts by weight and 0.2 parts by weight of trinonylphenyl phosphite per 00 parts by weight.

Incidentally, the polymer was sampled at the outlet of the first reactor and the second reactor, and the solvent was separated by steam stripping, and the first polymerization reaction and the second polymerization reaction were carried out by drying with a heated roll at 110°C. A sample of the polymer produced by the polymerization reaction of No. 2 was obtained. The oil-extended polymer sample was added to the polymer solution obtained at the outlet of the second reactor using highly aromatic process oil (JSRAROMA) per 100 parts by weight of the polymer.
After adding 37.5 parts by weight, the solvent was separated by steam stripping and dried with a hot roll at 110° C. to obtain a solution.

The polymerization conversion rate of 1,3-butadiene and styrene in the first stage polymerization reaction is determined by gas chromatography analysis of residual 1,3-butadiene and styrene in the polymer solution obtained at the outlet of the first reactor. I asked.

In addition, the bound styrene content is 100 MIIz 'If-N
It was determined using MR.

Block polystyrene content is 100MHz 'II-N
Using MR, it was determined as a percentage of the total bound styrene content from the absorption peak of block polystyrene that appears around a chemical shift of 6.5 ppm when tetramethylsilane is used as an internal standard.

The microstructure of the polybutadiene moiety was determined by infrared analysis (Morello method).

The gel content was determined as the proportion of insoluble matter after the dried polymer was stirred and dissolved in a toluene solvent at 50° C. for 15 hours.

The polymer vulcanizate was obtained by kneading with a Banbury and roll according to the formulation shown in Table 1, and vulcanizing the mixture at 145° C. for 40 minutes.

The above results are shown in Table-2.

From the above results, in the method of the present invention, no gel is generated even in continuous polymerization, and a random styrene-butadiene copolymer can be easily obtained. It can also be seen that the vulcanized product also has excellent rebound properties, abrasion resistance, tensile properties, and tear strength.

Example 2 In Example 1, 1,3-butadiene containing 1100 pp of 1,2-butadiene was used,
In addition, except that 0.75 g/hr of potassium dodecylbenzenesulfonate was used instead of the complex of 2-ethylhexanol and potassium nonylphenoxate, and the polymerization temperature of the first reactor and the second reactor was 75°C. The same procedure as 1 was carried out. The results are shown in Table-2.

Example 3 In Example 1, the rate of 1.3-butadiene in the first reactor was 1.65 kg/hr, and the rate of styrene was 1.05 kg/hr.
The same procedure as in Example 1 was carried out except that. The results are shown in Table-2.

Example 4 In Example 1, 1,2-butadiene in 1,3-butadiene was 1100 pp, and potassium salt was 0.161 g/
The same procedure as in Example 1 was carried out except that the supply was carried out in hours. The results are shown in Table-2.

Example 5 In Example 1, n-butyllithium 1.00 g/
hr.

Instead of the complex of 2-ethylhexanol and potassium nonylphenoxate, a complex of 2-ethylhexanol and t-butoxypotassium (molar ratio o, s: 1) was used at a concentration of 0.0% potassium per equivalent of lithium atom of n-butyllithium.
The same procedure as in Example 1 was carried out except that 4 equivalents were supplied. The results are shown in Table-2.

Example 6 In Example 1, n-butyllithium 1.00 g/
hr, 1,2-butadiene 0.596 g/hr 1
, 3-butadiene was added in addition to 1,2-butadiene and the polymerization temperature was set at 80°C.

The results are shown in Table-2.

Comparative Example 1 Example 1 except that the 1,3-butadiene supplied to the second reactor was stopped and the 1,3-butadiene supplied to the first reactor was increased to 2.25 kg/hr. The same procedure as 1 was carried out. The results are shown in Table-2.

The results show that vulcanizates containing a large amount of block polystyrene are inferior in terms of anti-ta elasticity.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the polymerization temperature in the first reactor was set to 60°C. The results are shown in Table-2.

In this comparative example, since the polymerization conversion rate of 1,3-butadiene in the first reactor is less than 90%, the polymer at the outlet of the second reactor contains a large amount of block polystyrene. - Vulcanized products of butadiene copolymers are inferior in terms of impact resilience.

Comparative Example 3 In Example 1, the amount of potassium salt was changed to 0.049 g/h.
The same procedure as in Example 1 was carried out except that the temperature was changed to r. The results are shown in Table-2.

In this comparative example, since the amount of potassium salt is small, the obtained styrene-butadiene copolymer contains a large amount of block polystyrene, and therefore the vulcanizate thereof is inferior in terms of impact resilience.

Comparative Example 4 In Example 1, the amount of potassium salt was changed to 3.88 g/hr.
The same procedure as in Example 1 was conducted except that the K/Li molar ratio was 0.53. The polymerization conversion rate of 1,3-butadiene at the outlet of the first reactor is 38%, the polymerization conversion rate of styrene is 42%, and the polymerization conversion rate of all monomers at the outlet of the second reactor is 52%.
Met. Furthermore, the Mooney viscosity before oil extension was 22, which was inappropriate as an oil extended rubber.

Comparative Example 5 In Example 1, 1,2-butadiene was 30 ppm (
The same procedure as in Example 1 was conducted except that 1,3-butadiene with a 1,2-BD/Li ratio of 0.067) was used.

After 24 hours had passed after the start of continuous polymerization, a large amount of gel adhered inside the first reactor, and the actual volume inside the reactor became extremely small, making it impossible to operate continuous polymerization.

The results are shown in Table-2.

Since the obtained styrene-butadiene copolymer contains gel, its vulcanizate is inferior in abrasion resistance, tensile properties, and tear strength.

Comparative Example 6 In Example 1, 1,2-butadiene was 900 pp+
The same procedure as in Example 1 was carried out except for using 1,3-butadiene in a. The results are shown in Table-2.

It can be seen that the Mooney viscosity and polymerization activity of the polymer are also reduced.

Comparative Example 7 The same procedure as in Example 1 was conducted except that no potassium salt was used and n-butyllithium was supplied at 1.35 g/hr. The results are shown in Table-2.

Comparative Example 8 The same procedure as in Example 1 was carried out except that 1,3-butadiene containing 5 ppm of 1,2-butadiene was used.

After 18 hours had passed after the start of continuous polymerization, a large amount of gel adhered to the inside of the first reactor, making it impossible to operate continuous polymerization.

Furthermore, since the obtained styrene-butadiene copolymer contains gel, its vulcanizate is inferior in tensile properties, tear strength, and abrasion resistance.

Table-1 Polymer 137.5 parts by weight Carbon black 6B, 8 Zinc white
4.0 Stearic acid
2.0〃Sulfur 2
．． 0 Vulcanization conditions 145°C 40 minutes Example 7 In a reactor with an internal volume of 71, 2250 g of cyclohexane/isoamicine (weight ratio 70/30), 325 g of 1,3-butadiene containing 300 ppm of 1,2-butadiene, and 150 g of styrene. , 0.08 mmol of potassium dodecylbenzenesulfonate and 0.005 mmol of ethylene glycol dibutyl ether, and the temperature of the mixture was set to 7.
The temperature was adjusted to 0°C.

Polymerization was started by adding 1.0 mmol of 5ee-butyllithium, and the polymerization was carried out for 20 minutes at a temperature of 70 to 80°C.

Sampling the polymerization reaction solution, the remaining 1,3-
When the amount of butadiene was measured by gas chromatography analysis, the polymerization conversion rate of 1,3-butadiene was 93%.

Next, 25 g of 1,3-butadiene was continuously added to the polymerization system over 8 minutes, and the polymerization was continued for an additional 8 minutes, after which 0.1 mmol of silicon tetrachloride was added.

After that, N,N-dimethylaminobenzaldehyde 0
．． 5 mmol was added to impart a tertiary amino group to the end of the polymer. The polymerization conversion rate at this time was 99.
It was 8%.

2,6-di-te per 100 parts by weight of polymer in the polymer solution.
0.5 g of r t-butyl-p-cresol was added, the solvent was removed by steam stripping, and the mixture was further dried with a roll to obtain a polymer.

The analytical results and vulcanized physical properties of the obtained polymer are shown in Table 3, and the formulation of the vulcanizate is shown in Table 4.

As a result, it can be seen that the copolymer of the present invention has a broader molecular weight distribution and excellent roll processability than Comparative Example 7, which is a stisane-butadiene copolymer obtained by a conventional method. It can also be seen that the physical properties of the vulcanized product are superior to those of Comparative Example 7 in tensile properties, tear strength, and abrasion resistance even though the rebound properties are the same.

Comparative Example 9 In Example 4, 1,3-butadiene containing 20 pp- of 1,2-butadiene was used, and 1,3-butadiene at the end of polymerization was
The same procedure as in Example 4 was carried out except that the addition of butadiene was discontinued and the initial addition of 1,3-butadiene was reduced to 350 g. The results are shown in Table-3.

Example 8 In Example 4, when the polymerization conversion rate of 1,3-butadiene was 98%, 25 g of 1,3-butadiene was added, and 0.1 mmol of silicon tetrachloride of Example 4 and N,N- Diphenylmethane diisocyanate 0 instead of 0.5 mmol dimethylaminobenzaldehyde
．． 9 mmol, then 1.0 mmol of 2
The procedure was as in Example 4 except that -ethylhexanol was used. The results are shown in Table-3.

Table-3 MW: Weight average molecular weight, Mn: Number average molecular weight: b
1modal Umbrella Umbrella: Shown as an index with Comparative Example 7 set as 100.

The larger the index, the better.

Table 4 Blending recipe Polymer - Part by weight Carbon black (HAF) 100 Zinc white 3 Stearic acid 22-Mercaptobenzothiazole
0.61.3-diphenylguanidine
0.4 I O
1
．． Effects of the 5f0 Invention According to the method for producing a styrene-butadiene copolymer of the present invention, there is no need to strictly control the composition ratio of 1,3-butadiene and styrene in the polymerization system, and the molecular Even in the presence of an allene compound added as a regulator, a styrene-butadiene copolymer with a high styrene content and randomness can be obtained, and the resulting styrene-butadiene copolymer has Since the styrene molecules of the vulcanizate have a random co-combination structure in which they are randomly arranged, the vulcanizate has excellent abrasion resistance, rebound resilience, tensile properties, and tear strength.

Procedure Written by Shufu (spontaneous) 1. Display of the case 1988 Patent Application No. 77068 2, Name of the invention Method for producing styrene-butadiene copolymer 3, Person making the amendment Relationship to the case Name of patent applicant (417) Japan Synthetic Rubber Co., Ltd. 4, Agent Man
107 Address: 3-2-3 Akasaka, Minato-ku, Tokyo (and 2 others) 5. Subject of amendment Contents of amendment (1) The scope of claims in the specification will be corrected as shown in the attached sheet.

(2) On page 5, line 8 of the same book, "Polymerization conversion rate is 95%" is corrected to "Polymerization conversion rate is 98%."

(3) Delete "so-called completely random" from lines 14 to 15 on the same page of the same book.

(4) On page 6 of the same book, line 15, "90%" is corrected to "98%."

(5) The same book, page 12, line 10, “60-90%”
60-98%,” he corrected.

(6) Same book, page 22, line 11: “0.596g/h
Correct "r" to "r O, 596g/hr".

(7) On page 29 of the same book, line 9, "Stisane-butadiene copolymer" is corrected to "styrene-butadiene copolymer."

(8) "Comparative Example 7" in lines 10 and 12 of the same page of the same book is corrected to "Comparative Example 9."

(9) “Example 4” on lines 16 and 19 of the same page in the same book
is corrected to "Example 9".

(10) "Example 4" in lines 2, 4, and 8 of page 30 of the same book is corrected to "Example 9."

(11) On page 31 of the same book, in the second line from the bottom, "Comparative Example 7" is corrected to "Comparative Example 9."

Claims (1) In a hydrocarbon solvent, 10 to 50 parts by weight of styrene and 90 to 50 parts by weight of 1゜3-butadiene are added as an organolithium initiator, per gram atom equivalent of lithium of the organolithium initiator. Potassium salt 0. When copolymerizing using 1 to 0.5 mol of O and 0.1 to 1.5 mol of an allene compound per gram atom equivalent of lithium as an organolithium initiator, i) of the total amount of 1,3-butadiene used in the polymerization; 60-9
ii) When the polymerization conversion rate of 1,3-butadiene in the polymerization system reaches 90 to 99.5%, the remaining 1 .3-butadiene or 1,3-butadiene and styrene once or twice
A method for producing a styrene-butadiene copolymer, which comprises adding the polymerization to a polymerization system several times or more continuously or intermittently.

(2) The method for producing a styrene-butadiene copolymer according to claim (1), wherein the allene compound is 1,2-butadiene.

Claims (2)

[Claims] (1) In a hydrocarbon solvent, 10 to 50 parts by weight of styrene and 90 to 50 parts by weight of 1,3-butadiene are mixed into an organolithium initiator, and 0.0. i) of the total amount of 1,3-butadiene used in the polymerization. 60-9
ii) When the polymerization conversion rate of 1,3-butadiene in the polymerization system is 90 to 99.5%, the remaining 1 , 3-butadiene or 1,3-butadiene and styrene once or twice
1. A method for producing a styrene-butadiene copolymer, which comprises adding the polymerization to a polymerization system several times or more continuously or intermittently. (2) The styrene compound according to claim (1), wherein the allene compound is 1,2-butadiene.
A method for producing a butadiene copolymer.