JPH0653768B2 - Method for producing modified diene polymer rubber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a modified diene polymer rubber, more specifically, a diene polymer having an active alkali metal terminal or an alkali metal addition And a conjugated diene polymer rubber represented by the general formula: (Wherein R ₁ , R ₂ and R ₃ are an alkyl group or an alkoxy group, R ₄ and R ₅ are an alkyl group, and n is an integer). The present invention relates to a method for producing a modified diene polymer rubber.

<Conventional Technology> Conventionally, conjugated diene polymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber have been used as rubbers for automobile tire treads. Due to the requirement of driving safety, a rubber material having a small rolling resistance and a large road surface grip on snow and ice has been desired as a rubber for an automobile tire red.

The rolling resistance correlates with the impact resilience of the polymer, and the higher the impact resilience, the smaller the rolling resistance.

On the other hand, the road grip on snow and ice is
It is known that there is a correlation with the IS hardness, and the lower the JIS hardness at low temperature, the greater the road surface grip on snow and ice. However, in the existing rubber material, these characteristics were not practically satisfactory.

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

<Means for Solving the Problems> The inventors of the present invention have conducted extensive studies to improve the impact resilience of the conjugated diene polymer rubber and to reduce the JIS hardness at low temperature. The present invention has been completed by finding that the above object can be achieved by reacting the combination with a specific compound and introducing a specific atomic group into the polymer.

That is, the present invention is 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. Rubber or
For a conjugated diene polymer rubber to which an alkali metal is added, which is obtained by reacting a diene polymer rubber having a conjugated diene unit in a polymer chain in a hydrocarbon solvent with an alkali metal catalyst, formula, (Wherein R ₁ , R ₂ and R ₃ represent an alkyl group or an alkoxy group, R ₄ and R ₅ represent an alkyl group, and n represents an integer). The present invention relates to a method for producing a modified diene polymer rubber.

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 with an alkali metal-based catalyst. Regardless of the type of alkali metal bound to the end of the diene polymer, and the polymerization method (eg, solution polymerization, emulsion polymerization, etc.), a diene polymer having a conjugated diene unit in the polymer chain is later formed. The one to which an alkali metal is added in the reaction of.

Examples of the diene polymer rubber include 1,3-butadiene, isoprene, 1,3-pentadiene (piperylene), 2,
Polymer or copolymer rubber of conjugated diene monomer such as 3-dimethyl-1,3-butadiene and 1,3-hexadiene, or styrene, α-methylstyrene, vinyltoluene copolymerizable with the conjugated diene monomer and the monomer , Vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene and other aromatic vinyl compounds, acrylonitrile and other unsaturated nitriles, (meth)
Examples thereof include, but are not limited to, a copolymer rubber with an ester of acrylic acid or vinyl pyridine.

Specifically, polybutadiene rubber, polyisoprene rubber,
Examples thereof include butadiene-isoprene copolymer rubber and butadiene-styrene copolymer rubber.

The diene polymer rubber in which an alkali metal is bonded to the end of the diene polymer rubber is, as described above, obtained by polymerizing the diene polymer rubber with an alkali metal-based catalyst, and at least the polymer chain. It is a living polymer before the termination of polymerization, in which an alkali metal is bonded to one end. It is possible to use a commonly used one such as an alkali metal-based catalyst, a polymerization solvent, a randomizer, a microstructure modifier for conjugated diene units, and the method for producing the polymer is not particularly limited.

Diene polymer rubbers obtained by adding an alkali metal to diene polymer rubbers include alkali metal base catalysts, alkaline earth metal base catalysts, solution polymerization using Ziegler catalysts, redox type catalysts, etc. Diene copolymer rubber obtained by polymerizing or copolymerizing the conjugated diene monomer or the conjugated diene monomer and a monomer copolymerizable therewith by a usual polymerization method such as emulsion polymerization (specifically, polybutadiene rubber, Polyisoprene rubber, butadiene-styrene copolymer rubber, butadiene-
Examples thereof include isoprene copolymer rubber, polypentadiene rubber, butadiene-piperylene copolymer rubber, and butadiene-propylene alternating copolymer rubber), but with an alkali metal added thereto.

Alkali metal addition to the diene polymer rubber may be carried out by a commonly used method. For example, a diene polymer rubber may be added to a hydrocarbon solvent in a conventional alkali metal base catalyst and an ether compound, an amine compound or a phosphine compound. The addition reaction is carried out in the presence of such a polar compound at a temperature of 30 to 100 ° C. for several tens of minutes to several ten hours. The amount of the alkali metal-based catalyst used is usually in the range of 0.1 to 10 mmol per 100 g of the diene polymer rubber. If the amount is less than 0.1 mmol, the impact resilience cannot be improved. Side reactions such as cutting occur and do not contribute to the improvement of impact resilience.

The polar compound is usually used for 1 mol of the alkali metal-based catalyst.
It is 0.1 to 10 mol, preferably 0.5 to 2 mol. An example of the alkali metal-based catalyst used in the polymerization and the addition reaction is as follows.

It is a complex with lithium, sodium, potassium, rubidium, cesium metal or their hydrocarbon compounds or polar compounds.

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

For example, ethyl lithium, n-propyl lithium, iso
-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-cyclopentyl lithium, 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 and the alkali metal addition reaction are carried out in a hydrocarbon solvent or a solvent that does not destroy the alkali metal-based catalyst such as tetrohydrofuran, tetrahydropyran and dioxane.

The suitable hydrocarbon solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons and alicyclic hydrocarbons, and particularly has 2 to 2 carbon atoms.
Propane having twelve, n-butane, iso-butane,
n-pentane, iso-pentane, n-hexane, cyclohexane, propene, 1-butene, iso-butene, trans-2-butene, cis-2-butene, 1-pentene,
2-Pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like are preferable. Further, these solvents can be used as a mixture of two or more kinds.

Next, the compound to be reacted with the above-mentioned alkali metal-containing diene polymer rubber used in the present invention has a general formula: (Wherein R ₁ , R ₂ and R ₃ represent an alkyl group or an alkoxy group, R ₄ and R ₅ represent an alkyl group, and n represents an integer).

Specific examples of such aminosilane compounds are shown below.

3-dimethylaminomethyltrimethoxysilane, 3-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminobutyltrimethoxysilane, 3-dimethylaminomethyldimethoxymethylsilane, 3-dimethylaminoethyl Dimethoxymethylsilane, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminobutyldimethoxymethylsilane, 3-dimethylaminomethyltriethoxysilane, 3-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 3 -Dimethylaminobutyltriethoxysilane,
3-dimethylaminomethyldiethoxymethylsilane, 3
-Dimethylaminoethyldiethoxymethylsilane, 3-
Dimethylaminopropyldiethoxymethylsilane, 3-
Examples thereof include dimethylaminobutyldiethoxymethylsilane, and particularly preferred is 3-dimethylaminopropyldiethoxymethylsilane.

The amount of the aminosilane compound used is such that when an alkali metal is added to an alkali metal-based catalyst or a diene polymer rubber used in the production of a diene polymer rubber in which an alkali metal is bonded to the terminal, in a subsequent reaction. The amount is usually 0.05 to 10 mol, preferably 0.2 to 2 mol, per mol of the alkali metal-based catalyst used.

Since the reaction between the aminosilane compound and the active conjugated diene-based polymer rubber having an alkali metal terminal or the conjugated diene-based polymer rubber to which an alkali metal is added occurs rapidly,
Although the reaction temperature and the reaction time can be selected within a wide range, it is generally room temperature to 100 ° C. and several seconds to several hours.

The reaction may be carried out by contacting the alkali metal-containing diene polymer rubber with the aminosilane compound. For example, the diene polymer rubber is polymerized using an alkali metal base catalyst and the aminosilane is added to the polymer rubber solution. A method of adding a predetermined amount of a compound, a method of reacting by adding the aminosilane compound after the completion of the alkali metal addition reaction in a diene polymer rubber solution can be exemplified as a preferable state, but is not limited to this method. Not something.

The resulting modified diene polymer rubber has an aminosilane compound introduced at the molecular end or in the molecular chain.

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

The crumb separated from the reaction system can also be dried by using a band dryer, an extrusion type dryer or the like used in the usual production of synthetic rubber, and the drying temperature is not limited at all.

The modified diene-based polymer rubber thus obtained has improved impact resilience and JIS hardness at low temperatures as compared with unmodified rubber, and thus is preferably used especially for automobile tires. Also, it can be used as a raw material rubber for various industrial purposes such as shoe soles, floor materials, anti-vibration rubbers, etc.

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

Example 1 A polymerization reactor made of stainless steel having an internal volume of 10 was washed, dried and replaced with dry nitrogen, and then 1000 g of 1,3-butadiene,
4300 g of n-hexane, 40 mmol of ethylene glycol diethyl ether and 6.0 mmol of n-butyllithium (n-hexane solution) were added, and polymerization was carried out at 50 ° C. for 1 hour while stirring.

After the completion of the polymerization, 4.1 mmol of 3-dimethylaminopropyldiethoxymethylsilane was added, and the reaction was carried out for 30 minutes while stirring. Then, 10 milliliter of methanol was added and the mixture was further stirred for 5 minutes.

Then, the contents of the polymerization reactor were taken out, and 5 g of 2,6-
Di-t-butyl-p-cresol (Sumura manufactured by Sumitomo Chemical Co., Ltd.
Iser BHT) was added, and most of n-hexane was evaporated.
After that, it was dried under reduced pressure at 60 ° C. for 24 hours.

The Mooney viscosity and 1,2-bonded monomer (by infrared spectroscopy) of the resulting polymer rubber were measured.

The resulting polymer rubber had a Mooney viscosity of 85 and a vinyl content of 70%.

Comparative Example 1 A polymer was obtained by the same method as in Example 1 except that 3-dimethylaminopropyldiethoxymethylsilane was not added.

The resulting polymer rubber had a Mooney viscosity of 85 and a vinyl content of 70%.

Example 2 A polymerization reactor made of stainless steel with an internal volume of 10 was washed, dried, and purged with dry nitrogen.
g, 250 g of styrene, 4300 g of n-hexane, 23 g of tetrahydrofuran, and 4.4 mmol of n-butyllithium (n-hexane solution) were added, and polymerization was carried out at 50 ° C. for 1 hour while stirring. After completion of the polymerization, 4.4 mmol of 3-dimethylaminopropyldiethoxymethylsilane was added, and the mixture was reacted for 30 minutes with stirring, then 10 milliliter of methanol was added, and the mixture was further stirred for 5 minutes.

Then, the contents of the polymerization reactor were taken out, and 5 g of 2,6-
Di-t-butyl-p-cresol (Sumilyzer BH
T) was added to evaporate most of the n-hexane,
It was dried under reduced pressure at 60 ° C. for 24 hours.

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

The resulting polymer rubber had a Mooney viscosity of 85, a styrene content of 25% and a vinyl content of 40%.

Comparative Example 2 A polymer was obtained by the same method as in Example 2 except that 3-dimethylaminopropyldiethoxymethylsilane was not added.

The resulting polymer rubber had a Mooney viscosity of 85, a styrene content of 25% and a vinyl content of 40%.

(Physical Properties of Compounded / Vulcanized Rubber) The polymer rubbers produced in Examples 1 and 2 and Comparative Examples 1 and 2 were kneaded on a roll according to the compounding recipe shown in Table 1 to obtain a compounded rubber, which was heated at 160 ° C. for 30 minutes. Press vulcanization was carried out under the conditions.

The impact resilience of the vulcanized rubber was measured at 60 ° C. using a Lupkeresilien tester. JIS hardness is JIS K63
01 at -20 ° C.

The results are shown in Table 2. from this result, The polymer of the present invention is a polymer obtained by the same method as the polymer of the present invention except that the aminosilane compound is not added, and a polymer not containing the aminosilane compound having the same Mooney viscosity as the polymer of the present invention. The impact resilience is extremely high and the JIS hardness at low temperature is extremely low.

Example 3 and Comparative Example 3 A stainless steel polymerization reactor having an internal volume of 10 was washed and dried to give a styrene-butadiene copolymer (Moonie viscosity 5
1, styrene content 25%, vinyl content 40%) 500 g,
4300 g of n-hexane was charged and dissolved with stirring. Then n
-Butyl lithium (n-hexane solution) (6.4 mmol) and tetramethylethylenediamine (6.4 mmol) were added, and the mixture was reacted at 70 ° C for 1 hour.

Next, 6.4 mmol of 3-dimethylaminopropyldiethoxymethylsilane was added, and the mixture was reacted for 30 minutes while stirring. Then, 10 milliliter of methanol was added and the mixture was stirred for further 5 minutes.

Then, the contents of the polymerization reactor were taken out, and 5 g of 2,6-
Di-t-butyl-p-cresol (Sumilyzer BH
T) was added to evaporate most of the n-hexane,
It was dried under reduced pressure at 60 ° C. for 24 hours. The obtained polymer mu
The knee viscosity was 51.

Next, the polymer was blended in the same manner as in Example 1 and the physical properties of the vulcanized rubber were measured.

For comparison, the styrene-butadiene copolymer (modified Mooney viscosity 51, styrene content 25%, vinyl content 40%) before modification was compounded by the same method and the physical properties of the vulcanized rubber were measured. .

The results are shown in Table 2.

<Effects of the Invention> As described above, according to the present invention, it is possible to provide a method for modifying a diene copolymer rubber that enhances impact resilience and reduces JIS hardness at low temperatures.

Claims (1)

[Claims] 1. An active conjugated diene 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 catalyst. Or, for a conjugated diene-based polymer rubber to which an alkali metal has been added, which is obtained by reacting a diene-based polymer rubber having a conjugated diene unit in a polymer chain in a hydrocarbon solvent with an alkali-metal-based catalyst. General formula, (Wherein R ₁ , R ₂ and R ₃ represent an alkyl group or an alkoxy group, R ₄ and R ₅ represent an alkyl group, and n represents an integer). A method for producing a modified diene polymer rubber.