JPH02263806A - Modified block copolymer rubber - Google Patents

Abstract

PURPOSE:To obtain the title rubber suitable for rubber material for tire tread, rubber material for the sole of sneakers to reduce energy consumption, etc., having high impact resilience and the end of molecular chain bonded to a specific atomic group, comprising a conjugated diene and an aromatic vinyl monomer. CONSTITUTION:Block copolymer rubber which contains the end of polymer chain bonded to at least one atomic group shown by formula I (R1 and R2 are N-dialkylamino) m and n are integers to show >=1 m+n) through C-C bond and 5-60wt.% aromatic vinyl monomer and comprises the aromatic vinyl monomer having >=10 Mooney viscosity (ML1+4, 100 deg.C) and a conjugated diene. The rubber is obtained by subjecting the aromatic vinyl monomer and the conjugated diene monomer to block copolymerization by using an alkali metal base catalyst to give a living block copolymer containing the end of molecular chain bonded to an alkali metal and reacting the living block copolymer with a benzophenone catalyst shown by formula II in a solution.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a block copolymer rubber of an aromatic vinyl monomer and a terminally modified conjugated diene in which a specific atomic group is bonded to the end of the molecular chain. .

(Prior Art) Block copolymers of conjugated dienes and aromatic vinyl monomers have been widely used as adhesives, modifiers for styrene resins, and the like.

Such block copolymers in which a sulfone group or a carboxyl group is bonded to the end of the molecular chain are known from US Pat. No. 3,471.431, US Pat. No. 4,020,036, US Pat. Incidentally, in recent years, due to demands for lower fuel consumption and driving safety of automobiles, there has been a strong desire for rubber materials for automobile tire treads that have low rolling friction resistance and high wet skid resistance.

However, these two characteristics are contradictory,
Various proposals have been made to harmonize both characteristics (
JP-A-54-62248, JP-A-56-1432
09.149413, etc.).

As a result of various studies on ways to harmonize the above two characteristics, the present inventor found that by bonding a specific atomic group to the end of the conjugated diene rubber, the impact resilience could be significantly increased without reducing the wet skid resistance. I have found that things can be improved. It was also found that the significant improvement in 1 impact resilience was the result of improved dispersibility of carbon black blended into the conjugated diene rubber. This effect can be obtained not only with rubber materials for tire treads, such as polybutadiene rubber, random copolymers of styrene and butadiene, but also with block copolymers of styrene and butadiene.

(Problems to be Solved by the Invention) An object of the present invention is to improve the repulsion elasticity. That is, the object of the present invention is to provide a novel block copolymer rubber of an aromatic vinyl monomer and a conjugated diene, which has improved filler dispersibility.

(Technical Means for Solving the Problems) According to the present invention, at least one atomic group represented by the general formula is bonded to the end of a polymer chain via a carbon-carbon bond.
A block copolymer of an aromatic vinyl monomer and a conjugated diene is provided, which has an aromatic vinyl monomer content of 5 to 60% by weight and a Mooney viscosity (ML+, 4,100°C) of 10 or more.

In the present invention, impact resilience is improved regardless of the structure of the block copolymer.

The block copolymer rubber of the present invention is obtained by block copolymerizing an aromatic vinyl monomer and a conjugated diene monomer by a known method using an alkali metal-based catalyst, and an alkali metal is bonded to one or both ends of the molecular chain. The active so-called living block copolymer has the general formula and man is an integer of 1 or more, respectively) and. (in which man represents an integer of 1 or more) are reacted in a solution with stirring.

The reaction temperature is usually in the range of room temperature to 100°C, preferably in the range of 30 to 80°C. After the HL reaction is completed, the block copolymer rubber of the present invention can be obtained by adding an allyl, water, hydrochloric acid, etc. to the reaction system.

A preferred embodiment of the reaction is to obtain a living block copolymer of an aromatic vinyl monomer and a conjugated diene in a hydrocarbon solvent using an alkali metal-based catalyst in a conventional manner, and after the completion of polymerization, add the living block copolymer to a solution of the polymer. This is a method in which a predetermined amount of the above-mentioned benzophenone derivative is added to carry out the reaction.

As the alkali metal-based catalyst, those commonly known as anionic polymerization catalysts can be used, including metal lithium, metal sodium,
Examples include alkali metals and organic alkali metal compounds such as metal rubidium and metal cesium.

As an organic alkali metal compound.

■One formula R- with one alkali metal in the same molecule
An organic monoalkali metal compound represented by M (in the formula, R is an alkyl group such as methyl, ethyl, propyl, butyl, amyl, hexyl, etc., an alkenyl group such as allyl, methallyl,
It is an aryl group, an alkaryl group, or an aralkyl group such as phenyl, xylyl, naphthalyl, etc., and M is lithium, potassium, rubidium, cesium, or um. ).

Examples of these include, for example, methyllithium.

Ethyllithium, propyllithium, butyllithium,
Hexyllithium, metallylithium, phenyllithium, lithium naphthalene, lithium anthracene, phenylisopropyllithium.

Potassium, lithium, etc. and these compounds.

Examples include compounds substituted with rubidium or cesium.

■Organic polyalkali metal compounds containing two or more alkali metals in the same molecule, such as 1,4-silydiobutane, 1,6-silydiohexane, 1,4-silydio-2
-butene, silydionaphthalene, 4,4-silydiobiphenyl, silydioanthracene, 1,2-silydio-1
, 1-diphenylethane, 1,2-silydiotriphenylethane, silydiomethane, etc., and compounds of these metal oxides substituted with lithium sodium, potassium A, rubidium or cesium.

(2) Examples include adducts of olefin compounds such as α-methylstyrene, styrene, isoprene, and dimethylbutadiene with alkali metals, and adducts of polycyclic aromatic compounds such as naphthalene, anthracene, phenanthrene, and biphenyl with alkali metals.

Conjugated dienes used to produce the block copolymer rubber of the present invention include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-
Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene, and vinylnaphthalene.

In the present invention, the production method of the block copolymer may be any known method and is not particularly limited (for example, Japanese Patent Publication No. 38-19286, Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 11JF45-31951, Japanese Patent Publication No. 11JF45-31951, Kosho 4
See Publication No. 8-32415, etc. N [).

The polymerization reaction is usually carried out in a hydrocarbon solvent or a solvent that does not destroy the alkali metal-based catalyst, such as tetrahydrofuran, tetrahydrobilane, dioxane, and the like. Suitable hydrocarbon solvents include n-aliphatic hydrocarbons, aromatic hydrocarbons,
selected from alicyclic hydrocarbons. In particular, carbon number 2-12
propane, tr-butane, i-butane, n-pentane,
i-pentane, n-hexane, cyclohexane, propene, 1-butene.

Trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, etc. are preferred, and these solvents are used in a mixture of 2N or more. You can also. Additionally, tetrahydrofuran, diethyl ether, dioxane, diethylene glycol, etc. are used to adjust the microstructure (1,2 linkage content) of the conjugated diene units in the polymer chain. Polar compounds such as ether compounds such as thyl ether, amine compounds such as tetramethylethylenediamine, trimethylamine, triethylamine, pyridine, and quinuclidine, and phosphine compounds such as triphenylphosphine can be used.

The amount of alkali metal-based catalyst used is usually 0.00 parts per 100 parts by weight of monomer. It ranges from 1 to 10 mmol. The amount of the polar compound used is usually in the range of 0 to 10 moles per mole of the catalyst.

The block copolymer obtained in this way is.

The effect of terminal modification can be obtained regardless of its structure, and the structure of the block copolymer is not particularly limited in the present invention.

For example, - formula (A-B), , A-+B-A)n, B-
(A-B),, ((A-B tear 1 door i-X, 1”(
A-B+-F- child = "Rho X represents a polyfunctional alkali metal-based catalyst residue, respectively), and the like.

The content of aromatic vinyl monomer in the block copolymer is 5 to 60% by weight. If it exceeds 60% by weight, rubber elasticity is lost, which is not preferable, and preferably 50% by weight or less. In addition, the Mooney viscosity (M
LI-4, ioo°C) is 10 or more. If it is less than 10, the strength will decrease. Preferably it is 30-150.

The benzophenone derivative to be reacted with the above-mentioned block copolymer having an active terminal is a compound represented by the general formula, and n is the number of m where ÷ n is 1 or more, and has either one of both benzene rings. It is necessary that at least one amino group is bonded to the amino group. A substituent other than the amino group may be bonded to the benzene ring.

Examples of preferred benzophenone derivatives include 4,4'
-bis(dimethylamino)-benzophenone, 4,4'
-bis(diethylamino)-benzophenone, 4.4'
-bis(dibutylamino)-benzophenone, 4-dimethylaminobenzophenone and the like.

It is desirable to use the benzophenone derivative in an amount in excess of the II stoichiometric amount with respect to the amount of the alkali metal bonded to the end of the block copolymer, and the preferred amount is 2 mol or less per 1 mol of the alkali metal. .

After the reaction is completed, the terminally modified block copolymer of the present invention can be separated from the reaction solution by a coagulation method such as steep stripping.

The benzophenone derivative bonded to the end of the block copolymer is CH if the end of the block copolymer has a 1,4-structure or a 1,2-structure with butadiene units, for example.

Combine as.

Further, when the end of the block copolymer is one, for example, a styrene unit, it is bonded as.

The present invention will be specifically explained below using Examples.

Example 1 A stainless steel polymerization reactor with an internal volume of 29 cm was washed, dried,
After purging with dry nitrogen, 60 g of styrene.

820 g of benzene, 0.5 mmol of diethylene glycol dimethyl ether, and 2.5 mmol of n-butyllithium (n-hexane solution) were added, and the contents were polymerized at 60° C. for 1 hour while stirring.

Next, a benzene solution containing 90 g of butadiene was added and the polymerization was continued for another 2 hours. After the completion of the first polymerization, 4,4
'-Bis(diethylamino)benzophenone (EAB)
Added 2.0 mmol of 6 and reacted for 15 minutes with stirring.
After the reaction, the contents of the polymerization reactor were poured into a 2.0% by weight methanol solution of 2,6-di-1-butyl-p-cresol, and the resulting terminal-modified polystyrene-polybutadiene block copolymer ( (abbreviated as SOB) was solidified and then dried under reduced pressure at 60° C. for 24 hours. GPC
The weight average molecular weight measured in terms of standard polystyrene is 8.
．． lXl0' Mooney viscosity (M L I◆4゜10
0°C) was 85. Also, the styrene content is 39.
It was 7% by weight.

Example 2 Active SB was obtained under the same conditions as in Example 1 except that the amount of styrene was changed to 30 g, and 30 g of styrene was added to obtain 1.
After completion of the 6-time polymerization, the resulting polymer was subjected to terminal modification under the same conditions as in Example 1. In this way, a terminal-modified block copolymer (5BS) was obtained with a weight average molecular weight of 8.
．． 0XIO' muuni viscosity is 87. Styrene content is 3
It was 9.3% by weight.

Example 3 In the same manner as in Example 1, 45 g of butadiene, 820 g of benzene, and 0.5 mmol% of diethylene glycol dibutyl ether n-butyl lithium (
After adding 2.5 mmol of n-hexane solution and polymerizing at 60°C for 1 hour with stirring, a benzene solution containing 60 g of styrene was added and polymerized for 2 hours, and then a benzene solution containing 45 g of butadiene was added. After further addition and polymerization for 1 hour, terminal modification was carried out under the same conditions as in Example 1. The obtained block copolymer (BSB) had a weight average molecular weight of 8.0×10′, a Mooney viscosity of 87, and a styrene content of 38.8% by weight.

Example 4 In the same manner as in Example 1, styrene 3 was added to a 2H polymerization reactor.
0 g, butadiene 45 g, diethylene glycol dimethyl ether 1 mmol, benzene 820 g, and n-butyllithium (n-hexane solution) 2.5 mmol were added, and polymerization was carried out at 60° C. for 2 hours with stirring. Further, a reaction mixture having the same composition as above was added and polymerized for 2 hours. After completion of the polymerization, terminal modification was performed under the same conditions as in Example 1 to obtain a Cheevered styrene-butadiene copolymer-tapered styrene-butadiene copolymer. Block copolymer (S/B-8
/B) was obtained. The weight average molecular weight of this product is 8.5X1
0', Mooney viscosity is 60, styrene content is 39.8
% by weight.

Each block copolymer of Examples 1 to 4 had EAB at its end.
It was confirmed by 13C-NMR measurement that these were bonded in the following structure.

100 to 150 milligrams of each block copolymer was dissolved in deuterated chloroform (CDCffs) 1+d and sealed in a sample tube with a diameter of 101 mm. Using JNM-FXI0ONMR surface trometer, room temperature, measurement frequency 25MHz =
Measurement was carried out under the conditions of iR1 constant frequency range of 500 Hz, pulse angle of 45 degrees, pulse repetition time of 15 seconds, and number of integrations of 78,920 times. Peak assignment was performed using EAB and 1,1-bis(p-diethylamino)phenyl-n-pentanol as a model substance. The peak of the carbon of the methyl group of the diethylamino group of EAB bound to the copolymer at 12.6 ppm, and the peak of the 113-carbon to which the OH group was bound at 111.3 ppm indicate that EAE is bound to the end of the block copolymer. It was confirmed that

In addition, after dissolving 2 g of the block copolymer purified by repeating dissolution and reprecipitation in 20 wd2 of toluene, 1 g and 1 acetic acid were added.
When 0- and 10-g of iodine were added, the color of the solution changed from colorless to back-colored, and a spectrum with maximum absorption at 633 nm was obtained. This indicates that the following reaction occurred, and it was confirmed that E and AB were bonded to the ends of one polymer in the above structure.

It was shown to.

In a block copolymer whose terminal end is not modified with EAB, neither the above-mentioned 1C-NMR peak nor a color change reaction is observed.

Example 5 A blended vulcanizate of each terminal-modified block copolymer of Examples 1 to 4 and each corresponding terminal-unmodified block copolymer was prepared, and the impact resilience was measured.

First, prepare a compound according to the following formulation, and add 1
! The test piece was press-vulcanized at 50°C for 20 minutes and its impact resilience at 23°C and 60°C was determined using a Dunlop tribometer. The results are shown in Table 1: Polymer HAF Carbon Black Aromatic Process Oil Zinc Flower Stearic Acid Sulfur N-oxydiethylene-2-bendithiazole sulfenamide From Table 1, the structure of the terminal-modified block copolymer of the present invention is shown. It can be seen that the impact resilience is significantly improved compared to the case where the terminals are unmodified regardless of the condition.

The values within are for the case where the end is unmodified (effect of the invention) The end-modified block copolymer rubber of the present invention has significantly improved impact resilience compared to the unmodified block copolymer rubber, so it has low transference. It can be used for applications such as rubber materials for tire treads that require resistance, rubber materials for sports shoe soles that reduce energy consumption, etc.

Claims (1)

[Claims] At the end of the polymer chain, there is a general formula ▲ a mathematical formula, a chemical formula, a table, etc. The content of an aromatic vinyl monomer in which at least one atomic group shown in ) is bonded with a carbon-carbon bond is 5 to 60
Weight%, Mooney viscosity (ML_1_+_4, 100°C)
A block copolymer rubber of an aromatic vinyl monomer having 10 or more and a conjugated diene.