JPS61231014A - Production of conjugated diene copolymer - Google Patents

Abstract

PURPOSE:To produce the titled copolymer excellent in rolling friction resistance, by polymerizing a vinyl aromatic compound with a conjugated diene compound under specified conditions. CONSTITUTION:To 100pts.wt. monomer mixture comprising 5-35pts.wt. vinyl aromatic compound and 95-65pts.wt. conjugated compound, 200-1,000pts.wt. hydrocarbon solvent, 0.01-0.2pt.wt. organolithium compound as an initiator and 0.01-3,000mol, per equivalent of Li atoms, of an ether and/or a tert. amine (e.g., ethylene glycol dimethyl ether). The polymerization of the mixture is started at -10-50 deg.C and continued at an elevated temperature <=150 deg.C. After the polymer conversion reaches 90-99%, 1-5pts.wt. conjugated diene compound is added continuously or intermittently and the polymerization is continued. This polymerization is stopped by the addition of a polyfunctional coupling agent (e.g., SnCl4) to obtain a conjugated diene copolymer having a total content of 1,2-bonds and 3,4-bonds of 20-70%.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for producing a copolymer having excellent rolling friction resistance properties.

b. Conventional technology In recent years, there have been demands for rubber materials for automobile tires to have low rolling friction resistance to improve fuel efficiency, high wet skid resistance to improve braking characteristics on wet roads, and high durability. In order to improve this, diene polymers with high breaking strength are required.

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

Problems to be Solved by the C8 Invention However, the recent demand for fuel efficiency from the automobile industry has become even more severe, and it is desired to further improve the fuel efficiency of the above-mentioned polymers.

Means for solving the d9 problem The present inventors have developed solution polymerization S using an organolithium initiator.
As a result of intensive studies to further improve the fuel efficiency of BR, we have arrived at the present invention.

That is, in order to solve the above-mentioned problems, the present invention provides, 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 form 1.2 bonds and 3
．． When producing a conjugated diene copolymer containing a total of 20 to 70% of 4-bonds, at the stage when the polymerization conversion rate reaches a range of 90 to 99%, 1 to 10 parts by weight of the monomer mixture is added. The present invention provides a method for producing a conjugated diene copolymer, which comprises adding 5 parts by weight of a conjugated diene compound continuously or intermittently, and further carrying out polymerization.

The conjugated diene copolymer obtained by the method of the present invention can be obtained by combining a vinyl aromatic compound and a conjugated diene compound in the presence of an ether or a tertiary amine at elevated temperatures or isothermal conditions until the polymerization conversion rate is 90 to 99%. Copolymerization of 0
Next, the polymerization conversion rate is 90 to 99%, more preferably 95 to 99%.
After reaching 99%, the content of the vinyl aromatic compound in the monomer increases, so a small amount of the conjugated diene compound is added continuously or intermittently from the outside into the polymerization system to generate random conjugated diene compounds. It becomes a copolymer.

If the conjugated diene compound is added continuously or intermittently when the polymerization conversion rate is less than 90%, the randomized polymerization of the conjugated diene and the vinyl aromatic compound will be incomplete, and a block polymer of the polyvinyl aromatic compound will be formed at the polymer terminal. is formed, the rolling friction resistance of the vulcanizate increases, and fuel efficiency is poor.

When the polymerization conversion rate exceeds 99%, a block polymer of the polyvinyl aromatic compound is formed before the conjugated diene compound is added, and rolling friction resistance may increase.

If the amount of the conjugated diene added is less than 1 part by weight, the randomization 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 lithium active terminals deactivated by impurities contained in the added conjugated diene will increase, and the coupling efficiency will decrease, especially when cambling with a tin compound etc. after the completion of polymerization, resulting in reduced rolling friction. Resistance characteristics are not improved, which is not preferable.

The conjugated diene compounds used in the present invention include 1.3-butadiene, isoprene, 1.3-pentadiene, 2.3-
Examples include dimethylbutadiene, preferably 1,3
-butadiene, isoprene.

Examples of the vinyl aromatic compound include styrene, P-methylstyrene, 0-methylstyrene, P-butylstyrene, and vinylnaphthalene, with styrene being preferred.

As the hydrocarbon solvent, one or more selected from butane, pentane, 2-methylbutene, 1-methylbutene, hexane, heptane, cyclohexane, methylcyclopenkune, octane, benzene, etc. can be used. The amount of hydrocarbon solvent is 2 to 10 parts by weight of the monomer mixture.
Parts by weight are used.

Examples of organic lithium compounds include n-butyllithium, 5
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 parts by weight per 100 parts by weight of the monomer.

Ethers and tertiary amines used include 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-methoxymethyltetrahydrofuran, 2,5
-dimethoxymethyltetrahydrofuran, N, N, N
'N'-tetramethylethylenediamine 1,1
．． 2-dilithiobutane, diethyl ether, tetrahydrofuran, dioxane, pyridine, triethylamine, etc. are used.

The amount of ether or tertiary amine used varies depending on the type, but is usually in the range of 0.01 to 3000 mol per 1 atom equivalent of lithium in the organolithium compound, and is in the range of 0.01 to 3000 mol per 1 atomic equivalent of lithium in the organolithium compound. The total amount of 2-bond and 3,4-bond gold is adjusted to be in the range of 20 to 70%.

The polymerization reaction is carried out using an organolithium compound as an initiator in the presence of an ether or a tertiary amine in a hydrocarbon solvent, and 5 to 35 parts by weight of a vinyl aromatic compound and 95 parts by weight of a conjugated diene compound.
65 parts by weight of a monomer mixture, the polymerization is initiated at a polymerization initiation temperature of 110 to 50°C, and is carried out at an elevated temperature of 150°C or less, or isothermally in the range of 0°C to 100°C. It takes place below.

The polymerization reaction can be followed by a reaction with a polyfunctional coupling agent. As the polyfunctional coupling agent, those described in Japanese Patent Publication No. 49-36957 can be used.

Preferably, the tin halide compound includes tin tetrachloride, dibutyldichlorotin, triphenyltin chloride, etc., and the organic carboxylic acid tin compound includes dibutyl dilauryl tin, butyl tristearyl tin, dimethyl distearyl tin, etc. There is. Vinyltin compounds include monovinyltributyltin and divinyldibutyltin, and isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and crude diphenylmethane diisocyanate.

Dialkyl- or amino-substituted aromatic compounds 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 below the polymerization temperature.

By reacting with a polyfunctional coupling agent, rolling resistance properties and breaking strength are improved.

The reaction time varies depending on the type of polyfunctional coupling agent, but is within 3 hours, usually within 1 hour.

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

e. Example In this example, the microstructure was measured using an infrared method (Morello method).
I asked for it. The styrene content was measured using an absorption peak of 699 cs-' based on the absorption of phenyl groups using a calibration curve determined in advance.

The tensile strength according to JIS K 6301 was used as an index for breaking strength.

The rolling friction resistance characteristics are tan δ measured at 50°C.
The value of was used. tan δ was measured using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho) (frequency 15 Hz)
.

The skid resistance was measured using a Stanley skid tester.

Sea urchin 7 tosked resistance was measured at room temperature.

Examples 1 to 10, Comparative Examples 1 to 5 [Preparation of Polymer A] 25% of cyclohexane was added to a 51 reactor purged with nitrogen.
00 g, butadiene 385 g, styrene 100 g
Prepare 12.5 g of tetrahydrofuran and set the temperature to 20
0.30 g of n-butyllithium was charged and polymerization was carried out under heat insulation. 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,
The reaction conversion rate reached almost 100% in 15 minutes. As an anti-aging agent, 0.5 parts by weight of 2,6-di-t-butylcatechol was added to 100 parts by weight of the polymer, and the mixture was desolubilized and dried in a conventional manner.

The vinyl bond Mooney viscosity (ML++4) of the butadiene moiety of the obtained copolymer was 40.

Furthermore, when the copolymer was analyzed by ozonolysis-gel permeation chromatography, the content of long chain blocks of styrene, in which 5 or more styrenes were bonded consecutively, was 5%.
% or less.

[Preparation of polymer B]

Polymerization was carried out using the same recipe as Polymer A. After the reaction conversion rate reached almost 100%, 0.2 mol of tin tetrachloride was added to 1 mol of n-butyllithium, and the vinyl bond in the butadiene moiety, the amount of bonded styrene, and the amount of block bonded styrene were the same as that of polymer A. [Preparation of Polymer C] Polymerization was performed using the same recipe as Polymer A.

After the reaction conversion rate reached almost 100%, tolylene was converted to 62
Met.

The vinyl bond in the butadiene moiety, the amount of bonded styrene, and the amount of block bonded styrene were the same as in Polymer A.

[Preparation of Polymer D]

Nitrogen-substituted 5I! Into a reactor, 2500 g of cyclohexane, 400 g of butadiene, and 1 g of styrene were added.
00g.

Prepare 12.5 g of tetrahydrofuran and set the temperature to 20
0.30 g of n-butyllithium was charged and polymerization was carried out under heat insulation, and the polymerization temperature reached 85°C.

After the reaction conversion reached approximately 100%, the same post-polymerization treatment as for Polymer A was carried out without adding butadiene. The amount of butathic bonded styrene in the obtained polymer was 25%.

[Preparation of polymer E-N]

Polymerization was carried out under heat insulation according to the recipe shown in Table 2. The amount of solvent, total monomer amount, n-butyllithium amount, and polymerization initiation temperature were the same as those of Polymer A.

The amount of tetrahydrofuran is 12.5g for polymer ENM.
.

The amount of polymer N was 20g.

Butadiene was added in a predetermined amount over a period of 5 to 15 minutes at a predetermined reaction conversion. After addition, the reaction conversion rate was approximately 100 within 15 minutes.
% has been reached. 0.2 mol of tin tetrachloride was added to 1 mol of n-butyllithium.

(5nC14 was not added for G and H) Then, desolubilization and drying were performed. Table 3 shows the ML of the obtained polymer, the vinyl bond in the butadiene moiety, the amount of bonded styrene, and the amount of block bonded styrene. The above polymers were kneaded using a 250 cc plastomill according to the formulation shown in Table 1 and vulcanized at 145° C. for 30 minutes, and the initial evaluation results are shown in Table 4.

Comparative Examples-1, 2, and 3 containing long-chain block polystyrene outside the scope of the present invention had poor rolling friction resistance characteristics;
In addition, in Comparative Examples 4 and 5, the amount of butadiene added continuously increased,
Since the coupling efficiency is lower than in Example-2, the rolling friction resistance characteristics are inferior.

Compared to these, the examples of the present invention provide polymers that are particularly excellent in rolling friction resistance properties, and also excellent in wet skid resistance and fracture strength.

f0 Effects of the Invention The copolymer obtained by the method of the present invention has excellent rolling friction resistance properties, and can be used alone or blended with other diene rubbers (natural rubber, BR, emulsion polymerized SBR, etc.) for ordinary rubber compounding. It can be suitably used in tire applications and various industrial products.

Claims (2)

[Claims] (1) In the presence of ether or tertiary amine in a hydrocarbon solvent, using an organolithium compound as an initiator, 5 to 35 parts by weight of a vinyl aromatic compound and 95 to 95 parts by weight of a conjugated diene compound
When producing a conjugated diene copolymer containing a total of 20 to 70% of 1,2 bonds and 3,4 bonds by polymerizing a monomer mixture consisting of 65 parts by weight, the polymerization conversion rate is 90 to 99%.
When the above range has been reached, 1 to 5 parts by weight of a conjugated diene compound is added continuously or intermittently to 100 parts by weight of the monomer mixture, and further polymerization is carried out. Method for producing a copolymer. (2) The method for producing a conjugated diene copolymer according to claim (1), which comprises terminating the polymerization with a polyfunctional coupling agent after completion of the polymerization.