JP2586085B2 - Method for producing modified diene polymer rubber - Google Patents

Description

The present invention relates to a method for producing a modified diene-based polymer rubber, and more particularly, to a conjugated diene-based polymer rubber having an active alkali metal terminal, and formula Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl groups, and n is an integer, wherein the acrylamide compound is reacted with a method for producing a modified diene polymer rubber. Things.

<Conventional Technology> Conventionally, conjugated diene-based polymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber have been used as rubber for automobile tire treads. Low rolling resistance as rubber for automobile tire tread
A rubber material having a large road surface slip on snow and ice has been desired.

The rolling resistance is correlated with the rebound resilience of the polymer, and the higher the repulsion, the lower the rolling resistance.

On the other hand, road grip on snow and ice
It is known that there is a correlation with the JIS hardness, and that the lower the JIS hardness at low temperatures, the greater the road surface grip on snow and ice. However, these properties have been unsatisfactory in practical use with existing rubber materials.

<Problems to be Solved by the Invention> An object of the present invention is to provide a method for modifying a diene-based polymer rubber that increases rebound resilience and reduces JIS hardness at low temperatures.

<Means for Solving the Problems> The present inventors have conducted intensive studies to increase the rebound resilience of the conjugated diene polymer rubber and lower the JIS hardness at low temperatures, and as a result, have found that the alkali metal-containing diene polymer has been obtained. And a specific compound, and by introducing a specific atomic group into the polymer, it has been found that the above object can be achieved, and the present invention has been completed.

That is, the present invention relates to an active conjugated diene-based polymer having an alkali metal terminal obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in a hydrocarbon solvent using an alkali metal-based catalyst. General formula for rubber (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl groups, and n is an integer) by reacting an acrylamide compound represented by the following formula: It is about the method.

The alkali metal-containing diene polymer used in the present invention is obtained by polymerizing a diene monomer or the monomer and another monomer copolymerizable therewith using an alkali metal base catalyst. The diene-based polymer terminal bonded to the resulting alkali metal.

Examples of the diene polymer rubber include polymers of conjugated diene monomers such as 1,3-butadiene, isoprene, 1,3-pentadiene (piperylene), 2,3-dimethyl-1,3-butadiene, and 1,3-hexadiene. Or a copolymer rubber, or a conjugated diene monomer and styrene copolymerizable with the monomer, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, aromatic vinyl compounds such as divinylnaphthalene, acrylonitrile and the like. Examples include, but are not limited to, unsaturated nitriles, (meth) acrylic acid esters or copolymer rubbers with vinylpyridine and the like.

Specific examples include polybutadiene rubber, polyisoprene rubber, butadiene-isoprene copolymer rubber, and butadiene-styrene copolymer rubber.

As described above, the diene polymer rubber in which the alkali metal is bonded to the end of the diene polymer rubber is obtained by polymerizing the diene polymer rubber with the alkali metal base catalyst,
An alkali metal is bonded to at least one end of the polymer chain,
Living polymer before termination of polymerization. It is possible to use commonly used ones such as an alkali metal base catalyst, a polymerization solvent, a randomizer, and a microstructure modifier of a conjugated diene unit, and the production method of the polymer is not particularly limited.

The amount of the polar compound is usually 0.1 to 10 mol, preferably 0.5 to 2 mol, per 1 mol of the alkali metal base catalyst. The following are examples of the alkali metal-based catalyst used in the polymerization.

Lithium, sodium, potassium, rubidium, cesium metals or complexes of these with hydrocarbon compounds or polar compounds.

Preferred are lithium or sodium compounds having 2 to 20 carbon atoms.

For example, ethyl lithium, n-propyl lithium, is
o-propyl lithium, n-butyl lithium, sec-butyl lithium, t-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium , 4-cyclopentyllithium, 1,4-dilithio-butene-2, sodium naphthalene, sodium biphenyl, potassium-tetrahydrofuran complex, potassium diethoxyethane complex, sodium salt of α-methylstyrene tetramer, and the like.

The polymerization reaction is a hydrocarbon solvent or tetrahydrofuran,
The reaction is performed in a solvent that does not destroy alkali metal-based catalysts such as tetrahydropyran and dioxane.

Suitable hydrocarbon solvents are selected from aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons.
Propane having ~ 12, n-butane, iso-butane,
n-pentane, iso-pentane, n-hexane, cyclohexane, propene, 1-butene, iso-butene, trans-2-butene, cis-2-butene, 1-pentene,
Preferred are 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These solvents can be used as a mixture of two or more kinds.

Next, the compound to be reacted with the alkali metal-containing diene polymer rubber used in the present invention has a general formula (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms, and n is an integer, preferably an integer of 2 to 5). Compound.

Specific examples of such an acrylamide compound are shown below.

N, N-dimethylaminomethylacrylamide, N, N-ethylmethylaminomethylacrylamide, N, N-diethylaminomethylacrylamide, N, N-ethylpropylaminomethylacrylamide, N, N-dipropylaminomethylacrylamide, N, N -Butylpropylaminomethylacrylamide, N, N-dibutylaminomethylacrylamide, N, N-dimethylaminoethylacrylamide, N, N-ethylmethylaminoethylacrylamide,
N, N-diethylaminoethylacrylamide, N, N-ethylpropylaminoethylacrylamide, N, N-dipropylaminoethylacrylamide, N, N-butylpropylaminoethylacrylamide, N, N-dibutylaminoethylacrylamide, N, N -Dimethylaminopropylacrylamide, N, N-ethylmethylaminopropylacrylamide, N, N-diethylaminopropylacrylamide, N, N-ethylpropylaminopropylacrylamide, N, N-dipropylaminopropylacrylamide, N, N-butylpropyl Aminopropylacrylamide, N, N-dibutylaminopropylacrylamide, N, N
-Dimethylaminobutylacrylamide, N, N-ethylmethylaminobutylacrylamide, N, N-diethylaminobutylacrylamide, N, N-ethylpropylaminobutylacrylamide, N, N-dipropylaminobutylacrylamide, N, N-butylpropyl Examples thereof include aminobutylacrylamide, N, N-dibutylaminobutylacrylamide and the like, and methacrylamide thereof, and particularly preferred is N, N-dimethylaminopropylacrylamide.

The amount of the acrylamide compound to be used is generally 0.05 to 10 mol, preferably 0.2 to 2 mol, per 1 mol of the alkali metal base catalyst used in producing the diene copolymer rubber having an alkali metal bonded to the terminal. It is.

Since the reaction between the acrylamide compound and the active conjugated diene-based polymer rubber having an alkali metal terminal occurs rapidly, the reaction temperature and the reaction time can be selected in a wide range,
Generally, the temperature is from room temperature to 100 ° C. and several seconds to several hours.

The reaction may be carried out by bringing the alkali metal-containing diene polymer rubber into contact with the acrylamide compound.For example, the diene polymer rubber is polymerized using an alkali metal base catalyst, and the acrylamide compound is added to the polymer rubber solution. The method of adding the compound in a predetermined amount can be exemplified as a preferable state, but is not limited to this method.

An acrylamide compound is introduced at the molecular end of the resulting modified diene polymer rubber.

After completion of the reaction, the modified diene polymer rubber uses the coagulation method used in the production of rubber by ordinary solution polymerization, such as addition of a coagulant or steam coagulation from the reaction solution, and the coagulation temperature is also limited at all. It has not been.

For drying the crumb separated from the reaction system, band dryers, extrusion dryers and the like used in the production of ordinary synthetic rubber can be used, and the drying temperature is not limited at all.

The modified diene polymer rubber thus obtained has improved rebound resilience and JIS hardness at low temperature as compared with unmodified rubber, so that it is particularly preferably used for automobile tires. Also, it can be used as a raw material rubber for various industrial uses such as shoe soles, flooring materials, and vibration-proof rubbers.

<Examples> Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A stainless steel polymerization reactor having an internal volume of 10 was washed, dried, and purged with dry nitrogen. Thereafter, 850 g of 1,3-butadiene, 150 g of styrene, 4300 g of n-hexane, and 9
g and 4.4 mmol of n-butyllithium (n-hexane solution) were added, and polymerization was carried out at 50 ° C. for 1 hour with stirring. After completion of the polymerization, N, N-dimethylaminopropylacrylamide
After adding mmol and reacting with stirring for 30 minutes, 10 ml of methanol was added and the mixture was further stirred for 5 minutes.

 The contents of the polymerization reactor were then removed and 5 g of 2,6-diene
-T-butyl-p-cresol (Sumirai Chemical Co., Ltd.
The BHT) and evaporated most of the n-hexane
Thereafter, the resultant was dried under reduced pressure at 60 ° C. for 24 hours.

The Mooney viscosity of the resulting polymer rubber was 77, and the vinyl content (by infrared spectroscopy) and the styrene content (by the refractive index method) were measured.

The resulting polymer rubber has a Mooney viscosity of 55 and a styrene content of
The vinyl content was 15% and the vinyl content was 31%.

Comparative Example 1 A polymer was obtained in the same manner as in Example except that N, N-dimethylaminopropylacrylamide was not added.

The resulting polymer rubber has a Mooney viscosity of 55 and a styrene content of
The vinyl content was 15% and the vinyl content was 31%. (Compounding / vulcanized rubber properties) The polymerized polymers of Example 1 and Comparative Example 1 were kneaded on a roll according to the compounding recipe shown in Table 1 to obtain a compounded rubber, which was pressed at 160 ° C for 30 minutes. Vulcanized.

The rebound resilience of the vulcanized rubber was measured at 60 ° C. using a Lupke resilience tester. JIS hardness is JIS K6301-
Measured at 20 ° C.

Table 2 shows the results. from this result, It can be seen that the polymer of the present invention has remarkably high rebound resilience and remarkably low JIS hardness at a low temperature, compared to a polymer obtained by the same method as the polymer of the present invention except that no acrylamide compound is added.

<Effect of the Invention> As described above, according to the present invention, the rebound resilience is increased,
It is possible to provide a method for modifying a diene-based copolymer rubber that reduces JIS hardness at low temperatures.

Claims (1)

(57) [Claims] An active conjugated diene-based polymer rubber having an alkali metal terminal obtained by polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in a hydrocarbon solvent using an alkali metal-based catalyst. For the general formula (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl groups, and n is an integer) by reacting an acrylamide compound represented by the following formula: Method.