JPH0625236B2 - Method for producing conjugated diene-based copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. TECHNICAL FIELD The present invention relates to a method for producing a copolymer having excellent rolling friction resistance characteristics.

b. 2. Description of the Related Art In recent years, as a demand for rubber materials for automobile tires, rolling friction resistance is low for low fuel consumption, high wet skid resistance is required for improving braking characteristics on wet road surfaces, and durability is improved. Therefore, a diene polymer having a high breaking strength is required.

Conventionally, these diene-based polymers have been disclosed in Japanese Examined Patent Publication No. 44-499.
No. 6, U.S. Pat. No. 3,956,232, JP-A-57-205414, etc., or a conjugated diene compound is polymerized in a hydrocarbon solvent using an organolithium initiator, or It is obtained by copolymerizing a conjugated diene compound and a vinyl aromatic compound and then reacting them with a tin halide compound and an alkenyltin compound.

c. Problems to be Solved by the Invention However, the recent demand for fuel economy from the automobile industry has become more severe, and it is desired to further improve the fuel economy of the above polymers.

d. Means for Solving the Problems The present inventors have proposed a solution polymerization S using an organolithium initiator.
The present invention has been achieved as a result of extensive studies to further improve fuel economy with BR.

That is, the present invention, in order to solve the above problems, in the presence of an ether or a tertiary amine in a hydrocarbon solvent,
Using an organolithium compound as an initiator, a monomer mixture consisting of 5 to 35 parts by weight of a vinyl aromatic compound and 95 to 65 parts by weight of a conjugated diene compound is polymerized to give 1,2 bonds and 3,3 parts.
When a conjugated diene-based copolymer containing 20 to 70% of 4 bonds in total is produced, 1 to 100 parts by weight of the monomer mixture is added when the polymerization conversion reaches a range of 90 to 99%. Disclosed is a method for producing a conjugated diene-based copolymer, which comprises adding 5 parts by weight of a conjugated diene compound continuously or intermittently, and further performing polymerization to terminate the polymerization with a polyfunctional coupling agent. To do.

The conjugated diene-based copolymer obtained by the method of the present invention comprises a vinyl aromatic compound and a conjugated diene compound at elevated temperature or isothermal temperature in the presence of ether or tertiary amine at a polymerization conversion rate of 90 to 99%. Are copolymerized.
Next, the polymerization conversion rate is 90 to 99%, more preferably 95 to 99%.
After the step of reaching 99%, the content of vinyl aromatic compound in the monomer becomes high. Therefore, a small amount of the conjugated diene compound is continuously or intermittently added to the polymerization system from the outside and the random conjugated diene compound is added. It becomes a system copolymer.

If the conjugated diene compound is added continuously or intermittently at a polymerization conversion rate of less than 90%, the randomized polymerization of the conjugated diene and the vinyl aromatic compound is incomplete, and the block polymer of the vinyl aromatic compound is less than the polymer. Are generated, the rolling friction resistance of the vulcanized product is increased, and the fuel efficiency is deteriorated.

If the polymerization conversion rate exceeds 99%, a block polymer of a polyvinyl aromatic compound may be produced before the addition of the conjugated diene compound to increase rolling friction resistance.

If the amount of the conjugated diene added is less than 1 part by weight, the randomized polymerization of the conjugated diene and the vinyl aromatic compound will be incomplete and the rolling friction resistance will increase. If the amount exceeds 5 parts by weight, the number of active lithium terminals that are deactivated by the impurities contained in the added conjugated diene increases, especially when coupling with a tin compound after the completion of polymerization, the coupling efficiency decreases and rolling friction The resistance characteristics are not improved, which is not preferable.

The conjugated diene compound used in the present invention is 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-
Examples include dimethyl butadiene, preferably 1,3
-Butadiene, isoprene.

As the vinyl aromatic compound, styrene, P-methylstyrene, O-methylstyrene, P-butylstyrene,
Examples thereof include vinylnaphthalene, and preferably styrene.

As the hydrocarbon solvent, one or more selected from butane, pentane, 2-methylbutene, 1-methylbutene, hexane, heptane, cyclohexane, methylcyclopentane, octane and benzene can be used. The amount of the hydrocarbon solvent is 2 to 10 with respect to 1 part by weight of the monomer mixture.
Used in parts by weight.

As the organic lithium compound, n-butyllithium, s
ec-butyllithium, tert-butyllithium, n
-Hexyllithium, 1,4-dilithiobutane, a reaction product of butyllithium and divinylbenzene, etc. are used. The amount of the organic lithium compound used is 0.01 to 0.2 part by weight based on 100 parts by weight of the monomer.

As the ether and the tertiary amine used, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, 2-methoxymethyl tetrahydrofuran, 2,
5-dimethoxymethyltetrahydrofuran, N, N,
N ', N'-tetramethylethylenediamine, 1,2-
Dipyridinoethane, diethyl ether, tetrahydrofuran, dioxane, pyridine, triethylamine and the like are used.

The amount of the ether or tertiary amine used varies depending on the kind thereof, but is usually in the range of 0.01 to 3000 mol per 1 atomic equivalent of lithium of the organolithium compound, and the average amount of the conjugated diene copolymer is 1. The total content of 2 bonds and 3,4 bonds is adjusted to be in the range of 20 to 70%.

The polymerization reaction is carried out in the presence of an ether or a tertiary amine in a hydrocarbon solvent using an organolithium compound as an initiator in an amount of 5 to 35 parts by weight of a vinyl aromatic compound and a conjugated diene compound 95.
~ 65 parts by weight of the monomer mixture is initiated at a polymerization initiation temperature of -10 to 50 ° C and is carried out at an elevated temperature of 150 ° C or lower, or isotherm in the range of 0 ° C to 100 ° C. Done below.

Following the polymerization reaction, a polyfunctional coupling agent is reacted. As a polyfunctional coupling agent, Japanese Examined Patent Publication Sho-49-36
Those described in Japanese Patent No. 957 can be used.

Preferably, the tin halide compound includes tin tetrachloride, dibutyldichlorotin, triphenyltin chloride, and the like, and the tin compound of the organic carboxylic acid includes dibutyldilauryltin, butyltristearyltin, dimethyldistearyltin, and the like. is there. Further, vinyltin compounds include monovinyltributyltin, divinyldibutyltin, and the like, and isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, crude diphenylmethane diisocyanate, and the like.

Examples of the dialkyl or amino-substituted aromatic compound containing at least one epoxy group, ketone group, aldehyde group, ester group, or nitrile group include those represented by the following general formula.

The reaction (treatment) with the polyfunctional coupling agent is not particularly limited, but is carried out at a temperature not higher than the polymerization temperature. By reacting with a polyfunctional coupling agent, rolling resistance characteristics and breaking strength are improved. The reaction time varies depending on the type of polyfunctional coupling agent, but is usually 3 hours or less, usually 1
Within time.

Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the Examples is not limited as long as the gist thereof is not exceeded.

e. Example In this example, the microstructure is infrared method (Morero method).
I asked. The styrene content was measured by an absorption peak based on the absorption of a phenyl group at 699 cm _-1 and a calibration curve that had been obtained in advance.

The breaking strength is based on the tensile strength according to JIS K 6301.

The rolling frictional resistance characteristic is tan δ measured at 50 ° C.
The value of was used. The smaller the tan δ at 50 ° C. measured with a viscoelasticity spectrometer (manufactured by Iwamoto Seisakusho), the better the rolling friction resistance characteristics.

The wet skid resistance was measured using a Stanley skid tester.

Wet skid resistance was measured at room temperature.

Examples 1 to 9 and Comparative Examples 1 to 6 [Preparation of Polymer A] Cyclohexane was added to the reactor of nitrogen substitution 5 at 25
00g, 385g of butadiene, 100g of styrene,
12.5 g of tetrahydrofuran was charged, and the temperature was 20 ° C.
Then, 0.30 g of n-butyllithium was charged and polymerization was carried out under adiabatic condition. When the polymerization conversion rate of the initially charged monomer was 96% (the temperature of the polymerization system reached 80 ° C.), 15 g of butadiene was continuously added for 5 minutes. After addition, 1
The reaction conversion reached almost 100% in 5 minutes. 2,6-di-t-butylcatechol as an anti-aging agent was added in an amount of 0.5 part by weight to 100 parts by weight of the polymer, and the mixture was dissolved and dried by a conventional method.

The vinyl bond content of the butadiene portion of the obtained copolymer was 4
8%, bound styrene content 20% by weight, Mooney viscosity Was 40.

When the copolymer was analyzed by ozonolysis-gel permeation chromatography, the long chain block content of styrene in which 5 or more styrenes were continuously bonded was 5
%Met.

[Preparation of Polymer B]

Polymerization was carried out with the same formulation as polymer A. After the reaction conversion reached almost 100%, 0.2 mol of tin tetrachloride was added to 1 mol of n-butyllithium. Then, it was removed by a conventional method and dried. Of the obtained polymer Was 70. The vinyl bond, the amount of bound styrene, and the amount of block bound styrene of the butadiene portion were the same as those of the polymer A.

[Preparation of Polymer C]

 Polymerization was carried out with the same formulation as polymer A.

After the reaction conversion rate reached almost 100%, 1 mol of tolylene diisocyanate was added to 1 mol of n-butyllithium. Of the obtained polymer Was 62.

The vinyl bond, the amount of bound styrene and the amount of block bound styrene in the butadiene portion were the same as those of the polymer A.

[Preparation of Polymer D]

Cyclohexane was added to the reactor 5 replaced with nitrogen in 25
00g, butadiene 400g, styrene 100g,
12.5 g of tetrahydrofuran was charged, and the temperature was 20 ° C.
Then, 0.30 g of n-butyllithium was charged and polymerization was carried out under adiabatic condition. The polymerization temperature reached 85 ° C. After the reaction conversion reached almost 100%, the same post-polymerization treatment as that for the polymer A was carried out without adding butadiene. The resulting polymer had a vinyl bond content in the butadiene part of 47%, a bound styrene content of 20% by weight, Was 46. The amount of block-bonded styrene was 25%.

[Preparation of Polymers E to N]

Polymerization was carried out under adiabatic conditions according to the formulations shown in Table-2. The amount of solvent, the amount of all monomers, the amount of n-butyllithium, and the polymerization initiation temperature were the same as those of the polymer A.

The amount of tetrahydrofuran is 12.5 for polymers E to M.
g, and the polymer N was 20 g.

Butadiene was added at a predetermined reaction conversion rate in a predetermined amount for 5 to 15 minutes. The reaction conversion rate is almost 100 within 15 minutes after the addition.
% Has been reached. 0.2 mol of tin tetrachloride was added to 1 mol of n-butyllithium. (S for G and H
NCL ₄ without adding) then desolvation was performed dry. Table 3 shows the ML of the obtained polymer, the vinyl bond of the butadiene part, the amount of bound styrene, and the amount of block bound styrene. The above polymers were kneaded in the compounding formulation shown in Table 1 using a 250 cc plastomill and vulcanized at 145 ° C. for 30 minutes, and the physical evaluation results are shown in Table 4.

Comparative Examples-2, 3 and 4 containing long-chain block polystyrene outside the scope of the present invention have poor rolling friction resistance characteristics,
In Comparative Examples 5 and 6, the amount of butadiene added was increased,
Since the coupling efficiency is lower than that of Example-1, the rolling friction resistance characteristic is inferior.

In comparison with these, the examples of the present invention are polymers having excellent rolling friction resistance characteristics, wet skid resistance and breaking strength.

f. EFFECTS OF THE INVENTION The copolymer obtained by the method of the present invention has excellent rolling friction resistance characteristics, and is used alone or in a blend with another diene rubber (natural rubber, BR, emulsion-polymerized SBR, etc.) for usual rubber compounding agents. Can be suitably used for tire applications and various industrial products.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area // (C08F 236/04 212: 06)

Claims (1)

[Claims] 1. An organolithium compound as an initiator in a hydrocarbon solvent in the presence of an ether or a tertiary amine,
A conjugated diene-based copolymer containing a total of 20 to 70% of 1,2 bonds and 3,4 bonds by polymerizing a monomer mixture consisting of 5 to 35 parts by weight of a vinyl aromatic compound and 95 to 65 parts by weight of a conjugated diene compound. When producing the polymer, the polymerization conversion rate is 90.
~ 99% range, the monomer mixture 10
1 to 5 parts by weight of the conjugated diene compound relative to 0 parts by weight,
A method for producing a conjugated diene-based copolymer, which comprises continuously or intermittently adding and further polymerizing and terminating the polymerization with a polyfunctional coupling agent.