JPH0657766B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a rubber composition which gives a vulcanized rubber having improved impact resilience and improved JIS hardness at low temperature.

More specifically, a rubber containing a diene polymer rubber having an active alkali metal terminal or a modified diene polymer rubber obtained by reacting a conjugated diene polymer rubber to which an alkali metal is added with a nitro compound as a rubber component. It relates to a composition.

<Prior Art> Conventionally, conjugated diene-based polymer rubbers such as polybutadiene and butadiene-styrene copolymer rubber have been used as rubbers for automobile tire treads, but in recent years demands for low fuel consumption of automobiles and snow and ice From the demand of running safety, a rubber material having a small rolling resistance and a large road grip on snow and ice has been desired as a rubber for an automobile tire tread.

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 rubber composition comprising an engine polymer rubber that enhances impact resilience and reduces JIS hardness at low temperatures.

<Means for Solving Problems> The present inventors have found that a rubber composition containing a conjugated diene-based polymer rubber as a rubber component has high impact resilience and J at low temperature.
As a result of repeated intensive studies to lower the IS hardness, an alkali metal-containing diene polymer is reacted with a specific compound,
It was found that the rubber composition containing the modified diene polymer rubber obtained by introducing a specific atomic group into a polymer as a rubber component can achieve the above-mentioned object, and thus completed the present invention.

That is, the present invention is obtained by reacting a diene polymer rubber having an active alkali metal terminal or a conjugated diene rubber to which an alkali metal is added with a nitro compound in a rubber composition comprising a rubber component and a compounding agent. The present invention relates to a rubber composition comprising a modified diene polymer rubber in an amount of at least 10% by weight in a rubber component.

The alkali metal-containing diene polymer used in the present invention is
Polymerization in which a diene monomer or another monomer and a monomer that can be co-weighed with the same are polymerized by using an alkali metal-based catalyst and an alkaline metal is bonded to the end of the diene polymer. Regardless of the method (for example, solution polymerization, emulsion polymerization, etc.), it is a diene polymer having a conjugated diene unit in the polymer chain, to which an alkali metal is added by a subsequent reaction.

The diene polymer rubber is a polymer of a conjugated diene monomer such as 1,3-butadiene, isoprene, 1,3-pentadiene (piperylene), 2,3-dimethyl-1,3-butadiene, or 1,3-hexadiene, or Copolymer, styrene copolymerizable with conjugated diene monomer, α-methylstyrene, vinyltoluene, vinylnaphthalene, aromatic vinyl compounds such as divinylbenzene, trivinylbenzene, divinylnaphthalene, unsaturated nitriles such as acrylonitrile, (meth Examples thereof include, but are not limited to, copolymer rubbers with acrylic acid esters such as 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 obtained by polymerizing the above-mentioned diene polymer rubber with an alkali metal-based catalyst, and at least one end of the polymer chain It is a living polymer in which an alkali metal is bonded and before the termination of polymerization. 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. The diene polymer rubber obtained by adding an alkali metal to a diene polymer rubber is an alkali metal base catalyst, an alkaline earth metal base catalyst, a solution polymerization using a Ziegler catalyst, or a redox type catalyst. A diene-based copolymer rubber (specifically, polybutadiene rubber) obtained by polymerizing or copolymerizing the conjugated diene monomer or the conjugated diene monomer described above and a monomer copolymerizable therewith by a usual polymerization method such as emulsion polymerization. , 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 100 g per 100 g of the diene polymer rubber.
It may be in the range of 0.1 to 10 millimoles, and if it is less than 0.1 millimoles, improvement of impact resilience cannot be obtained, and if it exceeds 10 millimoles, side reactions such as cross-linking and cutting of the polymer occur and do not contribute to 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 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 is a nitro compound having a nitro group in the molecule.

Specific examples of such nitro compounds are shown below.

(1) An aliphatic nitro compound can be mentioned.

Examples thereof include nitromethane, nitroethane, 1-nitropropane, 2-nitropropane, 1-nitro-n-butane, 2-nitro-n-butane, 2-methyl-1-nitrobutane, 3-methyl-1. -Nitrobutane, 2-methyl-2-nitrobutane, 1-nitro-n-
Hexane, 1-nitro-n-heptane, 1-nitro-n
-Octane, mononitroparaffins such as 2-nitro-n-octane, nitroethylene, 1-nitro-1-propene, 2-nitropropene, 3-nitro-1-propene, 1-nitro-1-butene, 2 -Nitro-2-butene, 1-nitro-2-methyl-1-propene, 2-nitro-1-butene, 2-nitro-1-pentene, 3-nitro-1,3-pentadiene, 2-nitro-3 -Methyl-
1,3-Butadiene, 1-nitro-4-methyl-1-pentene, 2-nitro-1-hexene, 2-nitro-1-
Heptene, 1-nitro-1-octene, 1-nitro-
Mononitroolefins such as 2,4,4-trimethyl-1-octene, chloronitromethane, bromonitromethane, 1-chloro-1-nitroethane, 1-bromo-1-
Nitroethane, 2-chloro-1-nitroethane, 1-chloro-1-nitropropane, 1-bromo-1-nitropropane, 2-chloro-1-nitropropane, 3-chloro-1-nitropropane, 1-chloro- 2-nitropropane, 1-bromo-2-nitropropane, 2-chloro-2
-Nitropropane, 1,1-dichloro-1-nitroethane, 1,1-dibromo-1-nitroethane, 1,1-dichloro-1-nitropropane, 1,1-dibromo-1-
Monohalogen nitroparaffins such as nitropropane, chloropicrin, brompicrin, methyl-2-nitroethyl ether, ethyl-2-nitroethyl ether,
2-nitroethyl-n-propyl ether, 2-nitroethyl isopropyl ether, n-butyl-2-nitroethyl ether, methyl-2-nitroisopropyl ether, 3-methoxy-2-nitrobutane, methyl-2-
Mononitroethers such as nitropropyl ether, n-butyl-2-nitroisopropyl ether, ethylnitro-tert-butyl ether, nitroacetone, 4,4
-Dimethyl-5-nitro-2-pentanone, methyl-2
-Mononitroketones such as nitroethylketone, 1,1
-Dinitroethane, 1,1-dinitropropane, 2,2
-Dinitropropane, 1,1-dinitropentane, 3,
3-dinitropentane, 1,2-dinitroethane, 1,
2-dinitropropane, 1,2-dinitrobutane, 2,
3-dinitrobutane, 2-methyl-2,3-dinitropropane, 2,3-dimethyldinitrobutane, 1,3-dinitropropane, 1,4-dinitrobutane, 1,5-dinitropentane, 1,6-dinitro Hexane, 2,2-
Dimethyl-1,3-dinitropropane, tetrochlor-
Dinitroparaffins such as 1,2-dinitroethane and tetrobrom-1,2-dinitroethane, dinitroolefins such as 2,3-dinitro-2-butene and 3,4-dinitro-3-hexene, trinitromethane, 1 , 1, 1
-Polynitro compounds such as trinitroethane, chlorotrinitromethane, bromotrinitromethane, iodotrinitromethane, tetranitromethane and hexanitroethane.

Further, (2) alicyclic nitro compounds can be mentioned.

Examples thereof include, for example, nitrocyclopentane, 1-
Methyl-1-nitrocyclopentane, 1-methyl-2-
Nitrocyclopentane, cyclopentylnitromethane,
Nitrocyclohexane, 1-methyl-1-nitrocyclohexane, 2-methyl-1-nitrocyclohexane, 4
-Methyl-1-nitrocyclohexane, 1,2-dimethyl-1-nitrocyclohexane, 1,3-dimethyl-1
-Nitrocyclohexane, 1,4-dimethyl-1-nitrocyclohexane, 1-bromo-1-nitrocyclohexane, 1,2-dinitrocyclohexane, 1-nitromethylcyclohexane, 1-nitromethylcyclohexene and the like can be mentioned.

Further, (3) aromatic nitro compounds can be mentioned.

Examples thereof include nitrobenzene, 1-chloro-3-nitrobenzoyl chloride, p-nitrophenyl-trifluoroacetate, o-dinitrobenzene, m-dinitrobenzene, 1,5-difluoro-2,4-dinitrobenzene, 3 , 5-dinitrobenzoyl chloride, p
-Dinitrobenzene, 1,2,3-trinitrobenzene, 1,2,4-trinitrobenzene, 1,3,5-trinitrobenzene, 1,2,3,5-tetranitrobenzene, 1,2,4,5- Tetranitrobenzene, o-fluoronitrobenzene, m-fluoronitrobenzene,
p-fluoronitrobenzene, 1-fluoro-2,4-
Dinitrobenzene, o-chloronitrobenzene, m-chloronitrobenzene, p-chloronitrobenzene, 1-
Chlor-2,4-dinitrobenzene, 1-chloro-2,
6-dinitrobenzene, 1-chloro-3,4-dinitrobenzene, 1-chloro-2,4,6-trinitrobenzene, 3,4-dichloronitrobenzene, 3,5-dichloronitrobenzene, 2,4-dinitrobenzene Chloronitrobenzene,
2,5-dichloronitrobenzene, 4,5-dichloro-
1,2-dinitrobenzene, 4,6-dichloro-1,3
-Dinitrobenzene, 2,5-dichloro-1,3-dinitrobenzene, 2,4,5-trichloronitrobenzene, 2-chloro-4-nitrotoluene, 2-chloro-6
-Nitrotoluene, 4-chloro-2-nitrotoluene,
2-chloro-3,4-dinitrotoluene, 2-chloro-
3,5-dinitrotoluene, o-bromonitrobenzene, m-bromonitrobenzene, p-bromonitrobenzene, 1-bromo-2,4-dinitrobenzene, 1-bromo-3,4-dinitrobenzene, 1-bromo-2,
4,6-trinitrobenzene, 2,3-dibromonitrobenzene, 3,4-dibromonitrobenzene, 2,4-
Dibromonitrobenzene, 2,6-dibromonitrobenzene, 4,6-dibromo-1,3-dinitrobenzene,
2,5-dibromo-1,4-dinitrobenzene, 2,
4,6-tribromonitrobenzene, 2-bromo-4-
Nitrotoluene, 2-bromo-5-nitrotoluene, 3
-Brom-2-nitrotoluene, 3-bromo-4-nitrotoluene, o-iodonitrobenzene, m-iodonitrobenzene, 1-iodo-2,4-dinitrobenzene, 1-iodo-3,4-dinitrobenzene, 3,4 ，
5-triiodonitrobenzene, 1-nitronaphthalene, 2-nitronaphthalene, dinitronaphthalene, trinitronaphthalene, tetranitronaphthalene, nitromethylnaphthalene, nitrophenylnaphthalene, halonitronaphthalene, halodinitronaphthalene, 5-nitrotetralin, 6-nitrotetralin,
5,6-dinitrotetralin, 5,7-dinitrotetralin, 5,8-dinitrotetralin, 6,7-dinitrotetralin, 3-nitro-1,2-naphthoquinone, 7-
Nitro-1,2-naphthoquinone, 3-methyl-2-nitro-1,4-naphthoquinone, 4-chloro-3-nitro-
1,2-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, nitroanthraquinone, p-
Examples thereof include dimethyl nitrophthalate, 4,4'-dinitrodiphenyl, 4,4'-dinitrodiphenylmethane and ethylbis (2,4-dinitrophenyl) acetate.

Furthermore, (4) heterocyclic nitro compounds can be mentioned.

Examples thereof include 7-chloro-4-nitrobenzofurazan, 2-chloro-5-nitropyridine, 2,4,5-trinitro-9-fluorene, 2,4,7-trinitro-.
Examples thereof include 9-fluorene and tetranitrocarbazole.

The amount of the nitro compound used is such that when an alkali metal is added to the alkali metal-based catalyst or the diene polymer rubber used in the production of a diene polymer rubber having an alkali metal 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 nitro 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, the reaction temperature and the reaction time can be selected within a wide range. Specifically, the temperature is from room temperature to 100 ° C and from several seconds to several hours.

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

The obtained modified diene polymer rubber has a nitro 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.

It is necessary that the improved diene polymer rubber is contained in the rubber composition in an amount of at least 10% by weight, preferably 20% by weight or more. If it is less than 10% by weight, improvement in impact resilience cannot be expected.

When the rubber is used in combination with another rubber, the other rubber is emulsion-polymerized styrene-butadiene copolymer rubber, solution polymerization (anionic polymerization catalyst, Ziegler type catalyst, etc.).
Polybutadiene rubber, styrene-butadiene copolymer rubber, polyisoprene rubber, butadiene-isoprene copolymer rubber, etc. and natural rubber. One or more of these rubbers are selected and used according to the purpose.

Mooney viscosity (ML) of modified diene polymer rubber
_{1 + 4} 100 ° C.) is usually in the range of 10 to 200, preferably 20 to 150. If it is less than 10, mechanical properties such as tensile strength are inferior, and if it exceeds 200, miscibility is poor when used in combination with other rubber and processing operability becomes difficult, and the vulcanized product of the obtained rubber composition is obtained. It is not preferable because the mechanical properties of are deteriorated.

All or part of the rubber component used in the present invention can be used as an oil-extended rubber.

The rubber composition of the present invention is produced by mixing the rubber component and various compounding agents with a mixing machine such as a roll and Banbury. The various compounding agents used are not particularly limited as long as they can be selected from those commonly used in the rubber industry, and those suitable for the purpose of use of the rubber composition can be selected.

Usually, the vulcanization type is sulfur, stearic acid, zinc white, various vulcanization accelerators (thiazole type, thiuram type, sulfenamide type, etc.) or organic peroxides, and the reinforcing agents are various types such as HAF and ISAF. Grade carbon black, silica and the like, fillers such as calcium carbonate and talc, and other compounding agents such as process oils, processing aids and anti-aging agents. The type and amount of these compounding agents are selected according to the purpose of use of the rubber composition, and are not particularly limited in the present invention.

Since the rubber composition of the present invention has improved impact resilience and JIS hardness at low temperatures, it is particularly preferably used for automobile tires. In addition, it is used for shoe soles, floor materials, anti-vibration rubber, etc. It can also be used as various industrial raw rubbers.

<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 stainless steel polymerization reactor having an internal volume of 10 was washed and dried,
1000 g of 1,3-butadiene after replacement with dry nitrogen, n
-Hexane 4300 g and ethylene glycol diethyl ether 40 mmol n-butyllithium (n-hexane solution) 6.0 mmol were added, and polymerization was carried out at 50 ° C for 1 hour with stirring. After completing the polymerization, add 3.0% of P-chloronitrobenzene.
After adding millimole and reacting for 30 minutes under stirring, 10 milliliter of methanol was added and further stirred for 5 minutes. Thereafter, the contents of the polymerization reactor were taken out, 5 g of 2,6-di-t-butyl-p-cresol (BHT) was added thereto, and most of n-hexane was evaporated, and then 60 ° C.
And dried under reduced pressure for 24 hours.

The Mooney viscosity and 1,2 bond unit content (by infrared spectroscopy) of the resulting polymer rubber were measured.

The resulting polymer rubber had a Mooney viscosity of 77 and a vinyl content of 70%.

The resulting polymer rubber was kneaded on a roll with each compound according to the compounding recipe in Table 1 to obtain a rubber composition.
Press vulcanization was carried out under the condition of 30 ° C for 30 minutes.

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 measurement results are shown in Table 2.

Comparative Example 1 A polymer and a rubber composition were obtained in the same manner as in Example 1 except that P-chloronitrobenzene was not added, and their physical properties were measured.

The polymer rubber produced has a Mooney viscosity of 23 and a vinyl content of 7
It was 0%.

Comparative Example 2 P-chloronitrobenzene was not added and n-
A polymer and a rubber composition were obtained in the same manner as in Example 1 except that butyllithium was 3.9 mmol, and the physical properties were measured.

The produced rubber had a Mooney viscosity of 77 and a vinyl content of 70%.

Example 2 A stainless steel polymerization reactor having an internal volume of 10 was washed and dried, and after substituting with dry nitrogen, 1000 g of 1,3-butadiene,
4300 g of n-hexane, 40 mmol of ethylene glycol diethyl ether, 5.0 mmol of n-butyllithium (n-hexane solution) were added, and the mixture was stirred at 50 ° C. for 1 hour.
Polymerization was carried out for a time. After the completion of the polymerization, 5.0 mmol of chloropicrin was added, and the mixture was reacted for 30 minutes with stirring.
Milliliter methanol was added and stirred for another 5 minutes. Then, the contents of the polymerization reactor were taken out and 5 g of 2,6
-Di-t-butyl-p-cresol (BHT) was added n
After evaporation of most of the hexane, it was dried under reduced pressure at 60 ° C. for 24 hours.

The resulting polymer rubber has a Mooney viscosity of 84 and a vinyl content of 7
It was 0%.

With respect to the obtained polymer rubber, a rubber composition was obtained in the same manner as in Example 1 and its physical properties were measured.

Example 3 It carried out like Example 2 except not adding chloropicrin.

The resulting polymer rubber had a Mooney viscosity of 46 and a vinyl content of 70%.

Comparative Example 4 The procedure of Example 2 was repeated, except that chloropicrin was not added and n-butyllithium was adjusted to 3.8 mmol.

The resulting polymer rubber had a Mooney viscosity of 84 and a vinyl content of 70%.

Example 3 A stainless steel polymerization reactor having an internal volume of 10 was washed and dried,
After substituting with dry nitrogen, 1000 g of 1,3-butadiene,
4300 g of n-hexane, 40 mmol of ethylene glycol diethyl ether, and 6.4 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, 3.2 mmol of dimethyl p-nitrophthalate was added, and the mixture was reacted for 30 minutes while stirring. Then, 10 milliliters 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 (BHT) was added and n
After evaporation of most of the hexane, it was dried under reduced pressure at 60 ° C. for 24 hours.

The resulting polymer rubber had a Mooney viscosity of 56 and a vinyl content of 70%.

With respect to the obtained polymer rubber, a gou composition was obtained in the same manner as in Example 1, and the physical properties were measured.

Comparative Example 5 The procedure of Example 3 was repeated, except that dimethyl p-nitrophthalate was not added.

The resulting polymer rubber had a Mooney viscosity of 17 and a vinyl content of 70%.

Comparative Example 6 No addition of dimethyl p-nitrophthalate and n
The same procedure as in Example 3 was repeated except that -butyllithium was 4.5 mmol.

The resulting polymer rubber had a Mooney viscosity of 56 and a vinyl content of 70%.

Example 4 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 6.4 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 polymerization, p-chloronitrobenzene was added to 3.
After adding 2 mmol and reacting for 30 minutes under stirring,
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 (BHT) was added and n
After evaporation of most of the hexane, it was dried under reduced pressure at 60 ° C. for 24 hours.

The produced polymer rubber had a Mooney viscosity of 77, a styrene content of 25% and a vinyl content of 40%.

With respect to the obtained polymer rubber, a rubber composition was obtained in the same manner as in Example 1 and its physical properties were measured.

Comparative Example 7 The procedure of Example 4 was repeated except that p-chloronitrobenzene was not added.

The resulting polymer rubber had a Mooney viscosity of 23, a styrene content of 25% and a vinyl content of 40%.

Comparative Example 8 No addition of p-chloronitrobenzene and n-
The same procedure as in Example 4 was repeated except that butyllithium was changed to 4.0 mmol.

The produced polymer rubber had a Mooney viscosity of 77, a styrene content of 25% and a vinyl content of 40%.

Example 5 A polymerization reactor made of stainless steel having an internal volume of 10 was washed, dried and replaced with dry nitrogen, and then 1,3-butadiene 750 was used.
g, styrene 250 g, n-hexane 4300 g, tetrahydrofuran 40 mmol, n-butyllithium (n-hexane solution) 5.2 mmol, and the mixture was stirred at 50 ° C. for 1 hour.
Polymerization was carried out for a time.

After the completion of the polymerization, chloropicrin (5.2 mmol) 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. After that, the contents of the polymerization reactor were taken out, 5 g of 2,6-di-t-butyl-p-cresol (BHT) was added to evaporate most of n-hexane, and then dried under reduced pressure at 60 ° C. for 24 hours. did.

The produced polymer rubber had a Mooney viscosity of 84, a styrene content of 25% and a vinyl content of 40%.

Hereinafter, a rubber composition was obtained in the same manner as in Example 1 and its physical properties were measured.

Comparative example 9 It carried out like Example 5 except not adding chloropicrin.

The resulting polymer rubber had a Mooney viscosity of 46, a styrene content of 25% and a vinyl content of 40%.

Comparative Example 10 The procedure of Example 5 was repeated except that chloropicrin was not added and n-butyllithium was set to 3.8 mmol.

The produced polymer rubber had a Mooney viscosity of 84, a styrene content of 25% and a vinyl content of 40%.

Example 6 A stainless steel polymerization reactor having an internal volume of 10 was washed, dried, and purged with dry nitrogen, and then 1,3-budadiene 750 was used.
g, 250 g of styrene, 4300 g of n-hexane, 23 g of tetrahydrofuran, 7.2 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, 3.6 mmol of dimethyl p-nitrophthalate was added, and the mixture was reacted for 30 minutes under stirring, then 10 milliliter of methanol was added, and the mixture was further stirred for 5 minutes.

Thereafter, the contents of the polymerization reactor were taken out, 5 g of 2,6-di-t-butyl-p-cresol (BHT) was added, and n-
After evaporating most of the hexane, it was dried under reduced pressure at 60 ° C. for 24 hours.

The resulting polymer rubber had a Mooney viscosity of 56, a styrene content of 25% and a vinyl content of 40%.

Hereinafter, a rubber composition was obtained in the same manner as in Example 1 and its physical properties were measured.

Comparative example 11 It carried out like Example 6 except not adding dimethyl p-nitrophthalate.

The produced polymer rubber had a Mooney viscosity of 17, a styrene content of 25% and a vinyl content of 40%.

Comparative Example 12 No dimethyl p-nitrophthalate was added and n
The same procedure as in Example 6 was repeated except that butyllithium was changed to 4.8 mmol.

The resulting polymer rubber had a Mooney viscosity of 56, a styrene content of 25% and a vinyl content of 40%.

Table 2 shows the results of measuring the physical properties of these examples and comparative examples.

From these results, the rubber composition of the present invention has the same Mooney viscosity as the rubber composition containing the polymer obtained by the same method as the polymer of the present invention and the polymer of the present invention except that the nitro compound is not added. It can be seen that the impact resilience is remarkably high and the JIS hardness at low temperature is remarkably low as compared with the rubber composition containing the polymer containing no nitro compound.

Example 7 and Comparative Example 13 A stainless steel polymerization reactor having an internal volume of 10 was washed and dried to obtain a styrene-butadiene copolymer (Moonie viscosity 5
1, styrene content 25%, vinyl content 40%) 500g,
4300 g of n-hexane was charged and dissolved with stirring. Then n
-Butyllithium (n-hexane solution) 6.4 mmol and tetramethylethylenediamine 6.4 mmol were added and reacted at 70 ° C for 1 hour.

Next, 3.2 mmol of p-chloronitrobenzene was added,
After reacting for 30 minutes under stirring, 10 milliliter of methanol was added and 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 (BHT) was added and n
After evaporation of most of the hexane, it was dried under reduced pressure at 60 ° C. for 24 hours.

Using the resulting polymer rubber, a rubber compounding composition was prepared according to the compounding recipe in Table 1, press-vulcanized to prepare a test piece, and physical properties were measured in the same manner as in Example 1.

The measurement results are shown in Table 2.

Also, using the unmodified steren-butadiene copolymer,
It carried out similarly and it was set as the comparative example 13.

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 rubber composition containing a diene copolymer rubber as a rubber component that enhances impact resilience and reduces JIS hardness at low temperatures. .

Claims (1)

[Claims] 1. A rubber composition comprising a rubber component and a compounding agent, which is obtained by reacting a diene polymer rubber having an active alkali metal terminal or a conjugated diene rubber having an alkali metal added with a nitro compound. A rubber composition comprising a diene polymer rubber in an amount of at least 10% by weight in a rubber component.