JP2000119446A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition which can give a vulcanizate having good processability, excellent wet skid resistance, low hysteresis loss, excellent abrasion resistance, and like excellent properties by blending an oil-extended rubber containing a tin-containing conjugated diene copolymer rubber and an extending oil with other diene rubbers, carbon black, silica, and a silane coupling agent. SOLUTION: This composition is obtained by blending (A) an oil-extended rubber containing 100 pts.wt. (A1) conjugated diene copolymer rubber obtained by copolymerizing a conjugated diene compound with a vinylaromatic compound in the presence of an initiator being an organolithium compound, reacting the copolymer with a tin compound and having a tin content of at least 50 ppm and 5-60 pts.wt. (A2) extending oil having a viscosity-specific gravity constant of 0.800-0.950 with 0-300 pts.wt., per 100 pts.wt. component A1, (B) diene rubber other than component A1, 0-100 pts.wt., per 100 pts.wt. total of components A1 and B, (C) carbon black, 5-100 pts.wt., per 100 pts.wt. total of components A1 and B, (D) silica, and 5-20 pts.wt., per 100 pts.wt. components D, (E) silane coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition comprising an oil-extended conjugated diene copolymer rubber and carbon black and silica or a carbon-silica double phase filler as a filler. Vulcanizates having excellent workability, wet skid properties, low hysteresis loss, and excellent balance of abrasion resistance.
The present invention relates to a rubber composition useful for an automobile tire tread.

[0002]

2. Description of the Related Art In response to recent demands for low fuel consumption of automobiles, a rubber material for tires has low rolling resistance, excellent wear resistance and breaking characteristics, and also has steering stability performance represented by wet skid resistance. A conjugated diene rubber composition is desired.

In order to reduce the rolling resistance of a tire,
Hysteresis loss of the vulcanized rubber may be reduced, and as an evaluation index of the vulcanized rubber, the rebound resilience at 50 to 80 ° C.,
A tan δ of up to 80 ° C., good-rich heat generation and the like are used. Large rebound resilience at 50-80 ° C or 50-80 ° C
A rubber material having a low tan δ or a small Goodrich heat generation is preferable. As rubber materials having a small hysteresis loss, natural rubber, polyisoprene rubber, polybutadiene rubber and the like are known, but these have a problem that wet skid resistance is low.

On the other hand, recently, as a rubber material for tires, there has been proposed a method of using a rubber composition in which silica or a mixture of silica and carbon black is blended as a reinforcing agent. However, tire treads containing silica or a mixture of silica and carbon black have low rolling resistance and good steering stability performance typified by wet skid resistance, but on the other hand, they have poor tensile strength and wear resistance of the vulcanizate. There is a problem of inferiority.

Japanese Patent Application Laid-Open No. 7-292162 discloses that when silica is used as a reinforcing filler,
As a general trend, compared to the case of using carbon black, heat resistance and related rolling resistance performance are better, and although the hardness and tensile strength of the vulcanized rubber compound are the same, the large deformation modulus Pointed out that there are problems such as low, poor abrasion resistance, high viscosity of the compound, high shrinkage of the compound and poor processability,
As a rubber composition that solves these problems, (A) a styrene-butadiene rubber having a carbon-tin bond in a molecule obtained by reacting an active lithium terminal with a tin compound using an organolithium compound as an initiator; (B) reinforcing silica filler, (C) reinforcing carbon black, (E)
There has been proposed a rubber composition for a tire containing a silane coupling agent, (F) an organic fatty acid, (G) a rubber extending oil, and the like.

[0006]

According to the study of the present inventors, the rubber composition proposed in the above-mentioned publication has improved the balance of various physical properties, but is still insufficient. In particular, it was found that improvement in workability was necessary. An object of the present invention is to provide a vulcanizate having good workability, a balance excellent in various properties such as wet skid characteristics, low hysteresis loss, and abrasion resistance, and useful for an automobile tire tread. It is to provide a rubber composition.

According to the present invention, the following rubber composition is provided to achieve the above object of the present invention. (1) (A) (A-1) A conjugated diene compound and a vinyl aromatic compound are copolymerized using an organolithium and / or lithium amide compound as an initiator, and then a tin compound as a coupling agent is reacted. The tin content is 5
100 parts by weight of a conjugated diene copolymer rubber of 0 ppm or more, and 5 to 60 parts by weight of (A-2) an extension oil having a viscosity specific gravity (VGC) of 0.800 to 0.950, In the oil-extended rubber contained, (B) a diene rubber other than the (A-1) conjugated diene copolymer rubber was added in an amount of 0 to 300 based on 100 parts by weight of the (A-1) conjugated diene copolymer rubber. Parts by weight, (C) carbon black, the total amount of the (A-1) conjugated diene copolymer rubber and the (B) diene rubber is 1
0 to 100 parts by weight with respect to 100 parts by weight, and (D) silica is added in an amount of 5 to 100 parts by weight based on the total amount of the (A-1) conjugated diene copolymer rubber and the (B) diene rubber.
1 to 100 parts by weight and 5 to 20 parts by weight of (E) a silane coupling agent with respect to 100 parts by weight of the silica. (2) (A) The oil-extended rubber (A) according to claim 1,
(B) A diene rubber other than the (A-1) conjugated diene copolymer rubber is (A-1) a conjugated diene copolymer rubber 10
0 to 300 parts by weight, and 0 to 300 parts by weight, and (F) the carbon-silica double-phase filler is 100% in total of the above (A-1) conjugated diene copolymer rubber and the above (B) diene rubber. A rubber composition characterized by being mixed in an amount of 1 to 100 parts by weight with respect to parts by weight. (3) Further, (G) a filler other than the carbon-silica dual-phase filler is added in an amount of 5 parts by weight based on 100 parts by weight of the total amount of the (A-1) conjugated diene copolymer rubber and the (B) diene rubber. The rubber composition according to the above (2), which is contained in an amount of from 100 to 100 parts by weight.

[0008] The rubber composition proposed in the above-mentioned JP-A-7-292162 also contains an extender oil.
The paragraph number [0040] of the publication states that "The rubber-like polymer composition of the present invention comprises a raw rubber, a reinforcing silica filler, a reinforcing carbon black, a silane coupling agent, a rubber extending oil, a rubber chemical, and the like. Is kneaded at a temperature of 140 to 180 ° C. using an internal mixer or the like, and after cooling the obtained composition, a vulcanizing agent such as sulfur and a vulcanization accelerator are further mixed with an internal mixer or a mixing roll. After being formed into a predetermined shape, it is vulcanized at a temperature of 140 to 180 ° C., and exhibits its performance in the state of a vulcanized rubber compound, and is used for a tire tread. ” As described above, the raw rubber and the extending oil are kneaded with other additives and the like to prepare a compounded rubber. The raw rubber is not oil-extended in advance, and the oil-extended rubber of the present invention is not used. This is clear from the description of the examples in the publication. In the present invention, an oil-extended rubber containing a specific conjugated diene copolymer rubber is used. As a result, in the kneading process of preparing a compounded rubber, a filler such as silica, carbon black, and a carbon-silica double phase filler is used. Is easily and finely dispersed in the conjugated diene copolymer rubber, and is excellent in various properties such as processability and vulcanizate, and as a whole, a highly balanced rubber composition can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The (A) oil-extended rubber used in the present invention contains (A-1) a conjugated diene-based copolymer rubber and (A-2) an extended oil. (A-1) Conjugated diene-based copolymer rubber is obtained by subjecting a conjugated diene compound and a vinyl aromatic compound to living anion copolymerization using an organic lithium and / or lithium amide compound as an initiator, and then forming a carbanion and tin at a polymer chain end. It is obtained by reacting a coupling agent comprising a compound.

The organic lithium as the anionic polymerization initiator is not particularly limited, but is represented by the general formula LiR ¹ (where R ¹ is an alkyl group having preferably 1 to 20 carbon atoms, and preferably 6 to 6 carbon atoms). 20 aryl groups, preferably 1-20 aralkyl groups, or 1 carbon atom
To 20); a general formula Li ₂ R
² (here, R ² is an alkyl group having preferably 1 to 20 carbon atoms, an aryl group having preferably 6 to 20 carbon atoms, an aralkyl group having preferably 1 to 20 carbon atoms, or a 1 to 20 carbon atom. 20 alkylene group etc.). Preferred specific examples of the organic lithium include n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium, dilithiomethane,
Examples thereof include 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene. Particularly, n-butyllithium, sec.
The use of -butyllithium and t-butyllithium is preferred. These organic lithiums can be used alone or in combination of two or more.

The lithium amide compound has the general formula LiN
It is a compound represented by R ¹ R ² . Here, R ¹ and R ² are
The same or different, an alkyl group having preferably 1 to 20 carbon atoms, an aryl group having preferably 6 to 20 carbon atoms,
An aralkyl group having preferably 7 to 20 carbon atoms, R ¹ , R ²
Are bonded to each other and have a carbon number of 3 to
Represents a ring structure of 7, but is not limited thereto. Among them, preferred lithium amide compounds are R ¹ and R ²
Is a compound in which R ¹ and R ² are bonded to each other to form a ring structure containing a nitrogen atom of the general formula. Preferred specific examples of the lithium amide compound include dimethylaminolithium, diethylaminolithium, diisobutylaminolithium, di-n-butylaminolithium, dipentylaminolithium, dioctylaminolithium, piperazine lithium, 2-methylpiperazine lithium, pyrrolidine lithium, and piperidine lithium. , 1-benzylpiperazine lithium, hexamethyleneimine lithium, heptamethyleneimine lithium, etc., and particularly preferred are diethylaminolithium, diisobutylaminolithium, di-n-butylaminolithium, pyrrolidine lithium, and piperidinelithium. These lithium amide compounds can be used alone or in combination of two or more.

The organic lithium and the lithium amide compound can be used alone or in combination.

When a lithium amide compound is used as an initiator, or when a lithium amide compound and an organic lithium are used in combination, a polymer chain having an amino group bonded to the terminal is formed. Since the amino groups are present in the system copolymer rubber and the interaction with the silica compounded in the rubber composition of the present invention is strengthened, the silica is not easily aggregated in the rubber component and is easily dispersed finely. As a result, the rubber composition of the present invention can obtain a vulcanizate having further improved processability and a well-balanced wet skid property, low hysteresis loss, and excellent wear resistance. (A-1) Conjugated diene copolymer rubber 10
The content of amino groups in 0 g is preferably from 0 to 2 mmol, particularly preferably from 0.01 to 1 mmol. The amino group content can be adjusted by the amount of the lithium amide compound used.

The organic lithium and / or lithium amide compound as an initiator is preferably 0.1 to 2 mmol, in terms of lithium, based on 100 g of the monomer.
More preferably, 0.2 to 1 mmol is used. Generally, when the molecular weight of the copolymer chain constituting the (A-1) conjugated diene copolymer rubber to be obtained is increased, the amount of the initiator used is reduced, and when the molecular weight is reduced, Use more.

The conjugated diene used for producing the (A-1) conjugated diene copolymer rubber of the present invention includes, for example,
3-butadiene, isoprene, 2,3-dimethyl-1,3
-Butadiene, 2-chloro-1,3-butadiene, 1,3
-Pentadiene and mixtures thereof, but are not limited thereto. Examples of the aromatic vinyl compound include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, and 4-tert-butylstyrene. , Divinylbenzene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethylstyrene, tert-butoxystyrene, vinylpyridine, and mixtures thereof. Not restricted. Of these, styrene is particularly preferred.

(A-1) The content of the bound aromatic vinyl compound bound in the conjugated diene copolymer rubber is preferably 3
0 to 50% by weight, more preferably 30 to 45% by weight. When the content of the bound aromatic vinyl compound is less than 30% by weight, wet skid characteristics and abrasion resistance are deteriorated. If it exceeds 50% by weight, the hysteresis loss increases.

(A-1) The content of 1,2-bonds and / or 3,4-bonds (hereinafter, referred to as "vinyl bonds") in the conjugated diene portion of the copolymer rubber is preferably 25 to 55%, more preferably. Is 28 to 55%, more preferably 30 to 4
5%. When the vinyl bond content is less than 25%, the wet skid characteristics are reduced, and the steering stability is poor. Also, 55
%, The wear resistance deteriorates and the hysteresis loss property increases.

(A-1) As described above, the conjugated diene copolymer rubber is obtained by subjecting a conjugated diene compound and a vinyl aromatic compound to living anion copolymerization, and then forming a cup comprising a carbanion at the polymer chain end and a tin compound. It is obtained by reacting a ring agent. As the tin compound, a general formula R
³ tin compounds represented by _(4-m) SnX _m are typical.
Here, R ³ is an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 15 carbon atoms, m is an integer of 2 to 4, and X is a halogen atom, preferably a chlorine atom or a bromine atom.

Specifically, when m is 4, tin tetrachloride and tin tetrabromide; when m is 3, monobutyltin trichloride and monooctyltin trichloride;
When m is 2, dibutyltin dichloride, dioctyltin dichloride and the like can be mentioned.

These tin compounds are obtained (A-
1) The conjugated diene copolymer rubber has a tin content of 50 ppm or more, preferably 50 to 600 ppm, more preferably 1 to 50 ppm.
It is used in such an amount that it becomes 00 to 500 ppm. When the tin content is in this range, good workability and low hysteresis loss are obtained, which is preferable. Further, the tin compound is preferably reacted with the living polymer chain in an amount of 0.1 to 1.0 equivalent, particularly preferably 0.2 to 0.6 equivalent.

When the tin compound represented by the above formula, in which m is 3 or 4, is used, it becomes a (A-1) conjugated diene copolymer rubber containing a branched polymer molecule, and the viewpoint of preventing cold flow. Is preferred.

When a tin compound having m of 3 or 4 and a tin compound having m of 2 are used in combination, a polymer chain having a branched carbon-tin bond and a polymer chain having a linear carbon-tin bond can be used. It becomes a copolymer rubber containing both of the united chains. Also,
In the present invention, a monofunctional tin compound, for example, a tin compound in which m in the above general formula is 1 and a polyfunctional tin compound, for example, a tin compound in which m is 2, 3, or 4 in the above general formula, May be used in combination. Examples of the compound when m is 1 include tributyltin chloride, triphenyltin chloride, and trioctyltin chloride. The proportion of the monofunctional tin compound is preferably not more than 50 mol% of the total amount of the tin compound used. Excessive use results in a large cold flow of the obtained (A-1) conjugated diene copolymer rubber, which causes a problem.

These tin compounds are reacted after copolymerizing a conjugated diene compound and a vinyl aromatic compound. Here, “reacting after copolymerization” does not necessarily mean that the reaction is performed after the copolymerization is completed. In the present invention, the tin compound can be added and reacted at any arbitrary stage during the copolymerization, that is, at any arbitrary stage during the copolymerization. Preferably, after the copolymerization is substantially completed, a tin compound is added,
It is desirable to react.

In the present invention, a tin compound as a coupling agent is added and reacted, and for example, a compound of the general formula R
¹⁰ _m Si (OR ¹¹ ) _4-m (where R ¹⁰ is a group having 1 to 2 carbon atoms)
0 represents an alkyl group, an aryl group, a vinyl group or a halogenated alkyl group, and R ¹¹ is a hydrocarbon group having 1 to 20 carbon atoms, preferably 4 to 20 carbon atoms, that is, OR is
20 alkoxy groups, preferably a non-hydrolyzable alkoxy group having 4 to 20 carbon atoms, and m is an integer of 1 to 3). An alkoxysilyl group can be introduced into the conjugated diene rubber. The addition amount of the silane compound is 0.01 to 0.5 with respect to 1 mol of organic lithium.
mol, particularly preferably 0.05 to 0.2 mol. The addition time of the silane compound may be simultaneous with, before or after the addition of the tin compound, but is preferably simultaneous. (A-1) When an alkoxysilyl group is introduced into the conjugated diene-based copolymer rubber, a bond with silica as a filler is generated, and the silica is more easily finely dispersed in the rubber composition of the present invention.

(A-1) The carbon-tin bond present in the conjugated diene copolymer rubber includes a butadienyl-tin bond and a styryl-tin bond, but the butadienyl-tin bond is preferred from the viewpoint of vulcanization properties. .

(A-1) The polymerization reaction and the modification reaction for obtaining the conjugated diene copolymer rubber are usually carried out at 0 to 120.
It is performed in a temperature range of ° C., and may be under a constant temperature condition or a rising temperature condition. The polymerization system may be either a batch polymerization system or a continuous polymerization system.

Also, if necessary, diethyl ether,
Ether compounds such as di-n-butyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, α-methoxytetrahydrofuran, dimethoxybenzene, dimethoxyethane and / or triethylamine, pyridine, N, N, N ′, N '-
Tertiary amine compounds such as tetramethylethylenediamine and dipiperidinoethane are added to the polymerization system to adjust the microstructure (vinyl bond content) of the conjugated diolefin portion of the diolefin-based copolymer and to increase the aromaticity. The randomness of the vinyl group compound can be improved.

Preferred examples of the hydrocarbon solvent used for producing the (A-1) conjugated diene copolymer rubber by copolymerizing a conjugated diene and a vinyl aromatic compound include pentane, hexane, heptane, octane, and the like. Examples include methylcyclopentane, cyclohexane, benzene, xylene and the like.

When the reactivity of the initiator used in the present invention is to be improved, or the aromatic vinyl compounds introduced into the polymer are randomly arranged, or a single chain of the aromatic vinyl compound is added. If you want to
A potassium compound may be added together with the polymerization initiator.
As the potassium compound added together with the polymerization initiator, for example, potassium alkoxide, potassium phenoxide, for example, potassium isopropoxide, potassium-t-butoxide, potassium-t-amyloxide, potassium-n-heptaoxide, potassium benzyl oxide, Potassium phenoxide and potassium alkoxide thereof, potassium alkoxide represented by potassium phenoxide, potassium phenoxide, isovaleric acid, caprylic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, benzoic acid, phthalic acid, 2 Potassium salts such as ethylhexanoic acid; dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid,
Potassium salts of organic sulfonic acids such as hexadecylbenzenesulfonic acid and octadecylbenzenesulfonic acid; organic phosphorous acids such as diethyl phosphite, diisopropyl phosphite, diphenyl phosphite, dibutyl phosphite and dilauryl phosphite And the like of potassium salt of organic phosphorous acid.

These potassium compounds can be added in an amount of from 0.005 to 0.5 mol per gram atomic equivalent of lithium of the organolithium compound used to form the initiator. If the amount is less than 0.005 mol, the effect of adding the potassium compound (improvement of the reactivity of the initiator, randomization of the aromatic vinyl compound or addition of a single chain) does not appear, whereas if it exceeds 0.5 mol, the polymerization activity is reduced. In addition, the productivity is greatly reduced, and the modification efficiency at the time of performing the reaction for modifying the polymer terminal with a functional group is reduced.

(A-1) When a conjugated diene copolymer rubber is produced by using a lithium amide compound as an initiator, the polymerization reaction activity is improved, and the reaction between the polymer active terminal and the coupling agent is carried out. For the purpose of improving the reaction efficiency, an alkali metal alkoxide compound may be added together with the polymerization initiator. The alkali metal alkoxide compound can be a reaction between an alcohol having a corresponding structure and an organic alkali metal compound, and the reaction is performed before copolymerizing the conjugated diolefin and the aromatic vinyl compound in a hydrocarbon solvent. The reaction may be performed in the presence of the monomer. Preferred examples of the alkali metal alkoxide compound include alkali metal alkoxides such as tetrahydrofurfuryl alcohol, N, N-dimethylethanolamine, N, N-diethylethanolamine, and 1-piperazineethanolamine.

As the organic alkali metal compound to be reacted with an alcohol compound to form an alkali metal alkoxide, an organic lithium compound is preferable. For example, ethyl lithium, propyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium,
Hexyllithium or a mixture thereof can be mentioned, and preferred are n-butyllithium and sec-butyllithium. The molar ratio of the alcohol compound to the organolithium compound needs to be 1: 0.7 to 1: 5.0, preferably in the range of 1: 0.8 to 1: 2.0, and more preferably. Is 1: 0.9 to 1: 1.2.
If the molar ratio exceeds 1: 5.0 and the amount of the organolithium compound is excessive, the effect of improving wear resistance and low hysteresis cannot be obtained. On the other hand, when the molar ratio is less than 1: 0.7 and the amount of the organolithium compound is too small, the polymerization rate is remarkably reduced, and the productivity is significantly reduced.
Modification efficiency at the time of performing a reaction for modifying a copolymer chain terminal with a functional group is reduced.

The (A-1) conjugated diene copolymer rubber has a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 20.
It is preferably in the range of 0, and if it is less than 20, wear resistance and low hysteresis loss deteriorate, and if it exceeds 200, workability deteriorates.

The (A-1) conjugated diene copolymer rubber is obtained by gel permeation chromatography (GP).
The weight-average molecular weight measured by the method C) is preferably 100,000 to 500,000, more preferably 2 to 100,000 in terms of polystyrene.
Desirably, it is in the range of 10,000 to 400,000. The molecular weight distribution is preferably from 1.1 to 4.0, and more preferably from 1.2 to 3.5, expressed as Mw / Mn.

Next, (A) constituting oil-extended rubber (A-
2) The extension oil will be described. The extender oil used has a viscosity specific gravity (VGC) of 0.800 to 0.95.
0, preferably 0.810 to 0.920.
Here, the viscosity specific gravity constant (VGC) is a value calculated by the following equation (1), and is well known to those skilled in the art.

[0036]

V.G.C. = {G−0.24−0.022log (V−35.5)} / 0.755 Formula (1)

In the above equation (1), G is specific gravity (60
/ 60 ^O F: 60 ^O and the mass of the sample in F, the ratio) between the mass of pure water of this volume at the same temperature, V is 210 ^O
It is Saybolt universal viscosity (SUS) in F. When such an extension oil (A-2) is oil-extended on the (A-1) conjugated diene copolymer rubber, the tin-carbon bond present in the copolymer rubber in the oil-extended state is not broken, and the oil is stable. Oil-extended rubber can be obtained.

(A-2) The extending oil is 5 to 60 parts by weight per 100 parts by weight of the (A-1) conjugated diene copolymer rubber,
Preferably, 10 to 50 parts by weight of oil is extended. The oil extension method is not particularly limited, and a known method can be employed. For example, a method of adding an extension oil to the polymerization solution can be used. This method is a preferable method because oil can be uniformly spread in operation. When the extender oil is added to the polymerization solution, a stage after completion of the polymerization is preferable. For example, a coupling agent is added and added after the reaction.

The rubber composition of the present invention may contain (B) a diene compound other than the (A-1) conjugated diene copolymer rubber. (B) As the diene rubber, unmodified vinyl aromatic compound-conjugated diene copolymer rubber, for example, unmodified styrene-butadiene rubber, modified styrene-butadiene rubber, other natural rubber, polyisoprene rubber, polybutadiene rubber, acrylonitrile- Butadiene rubber, chloroprene rubber and the like. Of these, preferred diene rubbers are natural rubber, polybutadiene rubber, modified styrene-butadiene rubber, and unmodified styrene-butadiene rubber. (B) Mooney viscosity (ML) of diene rubber
(1 + 4,100 ° C.) is preferably from 20 to 150, particularly preferably from 25 to 100. (B) The diene rubber is compounded in an amount of 0 to 300 parts by weight, preferably 0 to 250 parts by weight, based on 100 parts by weight of the (A-1) conjugated diene copolymer rubber. By using such a diene rubber (B) in the above range, the composition of the present invention can be produced at low cost without substantially impairing the performance of the rubber composition of the present invention.

In the rubber composition of the present invention, as a filler,
(C) carbon black and (D) silica, or (F) carbon-silica double phase filler (carbon-silica dual phase filler) is used.
(C) Carbon black produced by the furnace method and having a nitrogen adsorption specific surface area of 50 to 2
00m ² / g, DBP oil absorption 80-200ml / 10
0 g of carbon black is preferred, such as FEF, H
AF, ISAF, SAF class and the like can be preferably used, and a highly cohesive type is particularly preferable. As (D) silica, any of wet-process silica, dry-process silica, and synthetic silicate-based silica can be used. Silica having a small particle diameter has a high reinforcing effect, and a small particle / high agglomeration type (high surface area, high oil absorbing property) is particularly preferable in terms of physical properties and processability because of its good dispersibility in rubber. The nitrogen adsorption specific surface area of silica by the BET method is usually 50 to 40.
0 m ² / g, preferably from 100~220m ² / g.

(C) The compounding amount of carbon black is (A)
-1) The amount is 0 to 100 parts by weight, preferably 5 to 80 parts by weight, based on 100 parts by weight of the total amount of the conjugated diene copolymer rubber and the (B) diene rubber. The compounding amount of (D) silica is 5 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 100 parts by weight of the total of (A-1) conjugated diene copolymer rubber and (B) diene rubber. Department. The above (C) carbon black and (D) silica are added to the above (A-1) oil-extended rubber containing the specific (A-1) conjugated diene copolymer rubber and (A-2) a specific extender oil in the above range. Incorporation of these fillers makes these fillers with a reinforcing action uniformly and finely dispersed in rubber, and has excellent roll processability and extrudability, reduces hysteresis loss of the vulcanized product, and provides good rolling resistance. As a result, the wet skid resistance is improved and the wear resistance is excellent.

In the rubber composition of the present invention, other fillers, for example, fillers such as clay, calcium carbonate, magnesium carbonate, etc., may be blended together with (C) carbon black and (D) silica as required. it can. In this case, the compounding amount is based on 100 parts by weight of the total amount of (A-1) conjugated diene copolymer rubber and (B) diene rubber.
0 to 80 parts by weight is preferred.

In the rubber composition of the present invention, instead of using (C) carbon black and (D) silica together,
(F) A carbon-silica dual phase filler can be used, and the same excellent advantages can be obtained. Of course,
(F) With carbon-silica dual phase filler, (C)
Carbon black, (D) silica, and other fillers may be used in combination. (F) Carbon-silica dual phase filler (carbon-silica dual phase filler)
Is a filler that binds silica to the carbon surface and has a dual phase structure of a carbon black phase and a silica phase.
Product name CRX2002, CRX2000, CRX200
No. 6 sold by Cabot Corporation. (F) The compounding amount of the carbon-silica double phase filler is (A-1)
It is 1 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 100 parts by weight of the total amount of the conjugated diene copolymer rubber and the (B) diene rubber.

(F) Examples of fillers that can be used in combination with the carbon-silica dual phase filler include, but are not limited to, carbon black, silica, clay, calcium carbonate, and magnesium carbonate. Among them, carbon black and silica are preferred. These fillers that can be used in combination are 5 to 100 parts by weight, especially 10 to 80 parts by weight, based on 100 parts by weight of the total of (A-1) conjugated diene copolymer rubber and (B) diene rubber. It is preferred to be blended.

When (D) silica is blended as an essential filler, the (E) silane coupling agent is used in an amount of 5 to 20 parts by weight, preferably 6 to 20 parts by weight, per 100 parts by weight of (D) silica.
15 parts by weight are blended. Also, when (F) carbon-silica double phase filler is used as an essential filler,
(E) It is preferable to mix the silane coupling agent in the same amount as described above. The silane coupling agent has in the molecule both a functional group capable of reacting with the silica surface, such as an alkoxysilyl group, and a functional group capable of reacting with a rubber carbon-carbon double bond, such as a polysulfide, a mercapto group, or an epoxy group. Are preferred. For example, bis- (3-triethoxysilylpropyl) tetrasulfide, bis- (2
-Triethoxysilylethyl) tetrasulfide, 3-
Mercaptopropyltrimethoxysilane, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropylbenzothiazoletetrasulfide and the like are well known as silane coupling agents and are preferably used. it can. By using such a silane coupling agent, when silica or a carbon-silica double phase filler is used as a filler, the reinforcing effect can be enhanced.

In the rubber composition of the present invention, the vulcanizing agent comprises (A)
-1) It is usually used in the range of 0.1 to 6 parts by weight per 100 parts by weight of the total amount of the conjugated diene copolymer rubber and the (B) diene rubber. As the vulcanizing agent, sulfur is typically used, and in addition, a sulfur-containing compound, a peroxide and the like are used. In addition, sulfenamide-based in combination with a vulcanizing agent,
Guanidine-based, thiuram-based vulcanization accelerators are used in necessary amounts. Further, zinc white, a vulcanization aid, an antioxidant, a processing aid and the like are used in necessary amounts.

The rubber composition of the present invention comprises an oil-extended rubber, a diene-based rubber, a filler (carbon black, silica, a carbon-silica double phase filler, etc.), a silane coupling agent,
The additives and the like are kneaded at a temperature of 70 to 150 ° C. using a kneader such as a Banbury mixer. After cooling the obtained mixture, a vulcanizing agent such as sulfur and a vulcanization accelerator are further compounded using a Banbury mixer or a mixing roll, molded into a predetermined shape, and then vulcanized at a temperature of 140 to 180 ° C. Thus, a vulcanized rubber having an arbitrary shape, that is, a rubber product is produced.

The rubber composition of the present invention is suitably used for producing a tire tread, and is also suitably used for producing an anti-vibration rubber, a belt, a hose, industrial articles, footwear and the like.

[0049]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the scope of the present invention. Various measurements in the examples were performed according to the following methods. (1) Vinyl content of conjugated diolefin portion It was determined by an infrared absorption spectrum method (Morello method). (2) Bound styrene content A calibration curve was prepared and determined by infrared absorption spectroscopy. (3) Mooney viscosity The Mooney viscosity was measured according to JIS K6300 at an L rotor, preheating for 1 minute, rotor operation time for 4 minutes, and a temperature of 100 ° C. (4) Tin-carbon bond content After dissolving the sample (polymer) in toluene, the tin compound not bonded to the polymer is separated from the polymer by precipitating in a large amount of methanol, and dried. The purified polymer was analyzed by atomic absorption spectroscopy to determine the tin concentration in the polymer. (5) Amino group content Robert T. Keene, James S. Fritz,
J. Anal. Chem. 24, 564 (195
2 years) and the "acid-base titration method in an organic solvent using a perchloric acid-acetic acid solution" described below. Chloroform was used as a solvent for dissolving the sample, and methyl violet was used as a titration indicator, and quantification was performed by a calibration curve prepared in advance using a tri-n-octylamine solution having a known concentration.

(6) Evaluation of physical properties of vulcanized product The raw rubber was kneaded with a 250 cc Labo Plastomill according to any of the compounding formulations shown in Table 4, and then kneaded.
Various measurements were performed using the vulcanized product that had been vulcanized at 45 ° C. for a predetermined time. (A) tan δ (50 ° C.), tan δ (0 ° C.) Using a dynamic spectrometer manufactured by Rheometrics, Inc., the measurement was performed under the conditions of tensile dynamic strain 1%, frequency 10 Hz, and 50 ° C. Indicated by an index, the larger the numerical value, the smaller and better the rolling resistance. Also, tan δ (0 ° C.)
Uses the same equipment, tensile dynamic strain 0.1%, frequency 10H
z, measured at 0 ° C. Expressed as an index, the larger the numerical value, the greater and better the wet skid resistance.

(Ii) Lambourn abrasion index Using a Lambourn abrasion tester, the slip ratio was represented by the amount of abrasion at 25%, and the measurement temperature was room temperature. The higher the index, the better the wear resistance. (C) Workability (i) Kneading workability Evaluation was made based on the remaining amount of filler 3 minutes after the start of kneading. (Ii) Roll wrapping property and extruded skin The dump rubber after kneading was visually inspected for unity, gloss appearance and wrapping around the roll, and evaluated.

Example 1 (Preparation of copolymer rubber A and its oil-extended rubber and evaluation thereof) In a 5-liter autoclave reactor purged with nitrogen, 2,500 g of cyclohexane, 25 g of tetrahydrofuran, 100 g of styrene, 100 g of 1, 3-butadiene 35
0 g and 3.45 mmol of pyrrolidine were charged. After adjusting the temperature of the contents of the reaction vessel to 100 ° C., 3.45 mmol of n-butyllithium was added to initiate polymerization. The polymerization was carried out under adiabatic conditions and the maximum temperature reached 85 ° C. After the polymerization conversion reached 100%, 50 g of butadiene was added, and after 5 minutes, 0.5 mmol of tin tetrachloride was added to carry out a reaction for 15 minutes. After the reaction, 2,6-di-
t-Butyl-p-cresol was added, and 18 parts of the extending oil (trade name: Naplex 32, manufactured by Mobil Petroleum) were added.
7.5 g (37.5 parts by weight based on 100 parts by weight of rubber)
After the addition, the solvent was removed by steam stripping, and the rubber was dried with a hot roll at 115 ° C. to obtain an oil-extended rubber.
The rubber produced by the polymerization is referred to as copolymer rubber A. Table 4 shows the composition of the copolymer rubber A and the oil-extended rubber. Using the oil-extended rubber prepared above, the formulation II shown in Table 6
The compounded rubber prepared by the above was vulcanized to evaluate physical properties. Table 7 shows the results.

Examples 2 to 7 (Preparation of Copolymer Rubbers BG and Oil-Extended Rubber and Evaluation thereof) In Example 1, the polymerization recipe and the coupling recipe were changed as described in Tables 1 and 2. Example 1 except that
In the same manner as described above, modified polymers B, C, D, E and F were synthesized, and their oil-extended rubbers were prepared. Table 4 shows the composition of the obtained copolymer rubber and the oil-extended rubber. Using the oil-extended rubber thus prepared, the compounded rubber prepared according to the compounding formula II shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 7 shows the results.

Examples 8 and 9 (Preparation of copolymer rubbers H and I, their oil-extended rubbers, and evaluation thereof) In Example 1, the polymer formulation and the coupling formulation were changed as shown in Table 2. Except for the above, modified polymers H and I were synthesized and oil-extended rubbers were prepared in the same manner as in Example 1. Tables 4 and 5 show the composition and the like of the obtained copolymer rubber and oil-extended rubber. Using the oil-extended rubber thus prepared, the compounded rubber prepared according to the compounding formula II shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 7 shows the results.

Comparative Examples 1 to 6 Modified polymerized rubbers J and K were prepared in the same manner as in Example 1 except that the polymerization recipe and the coupling recipe were changed as shown in Tables 2 and 3. , L, M, N, and O were synthesized, and the oil-extended rubber was prepared (however, in Comparative Example 2, the oil-extended rubber was not prepared, and the copolymer rubber K was directly used for the preparation of the compounded rubber). . Table 5 shows the composition and the like of the obtained copolymer rubber and oil-extended rubber. Using the oil-extended rubber thus prepared, the compounded rubber prepared according to the compounding formula II shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 8 shows the results.
And Table 9 below.

Examples 10 and 11 Using the oil-extended rubber prepared in Example 1, compounded rubbers prepared according to Compounding Formula I (Example 10) and Compounding Formula III (Example 11) shown in Table 6 respectively. Was vulcanized and physical properties were evaluated. Table 8 shows the results.

Comparative Example 7 Using the oil-extended rubber prepared in Comparative Example 2, the compounded rubber prepared according to the compounding formula I shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 9 shows the results. Comparative Example 8 Using the oil-extended rubber prepared in Example 1, the compounded rubber prepared according to the compounding formula V shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 9 shows the results. Comparative Example 9 Using the oil-extended rubber prepared in Example 1, the compounded rubber prepared according to the compounding formula IV shown in Table 6 was vulcanized, and the physical properties were evaluated. Table 9 shows the results.

[0058]

[Table 1] (* 1) DBSK: potassium dodecylbenzenesulfonate (* 2) Si69: bis (3-triethoxysilylpropyl) tetrasulfide

[0059]

[Table 2] (* 1) DBSK: potassium dodecylbenzenesulfonate

[0060]

[Table 3] (* 1) DBSK: potassium dodecylbenzenesulfonate

[0061]

[Table 4] (1) Naplex 32 (manufactured by Mobile Sekiyu KK) (2) FUKKOR FLEX # 1400N (manufactured by Fuji Kosan) (3) Shellflex 680 (manufactured by Showa Shell Sekiyu) (4) Shellflex 220RS (manufactured by Showa Shell Sekiyu) (5) Pyrrolidine lithium (lithium amide compound) (6) n-butyllithium

[0062]

[Table 5] (1) Naplex 32 (manufactured by Mobil Oil) (5) Lithium pyrrolidine (lithium amide compound) (6) n-butyllithium (7) Fucall AROMA # 3 (manufactured by Fujikosan) (8) Sonic process oil P-200 (Kyodo Oil Co., Ltd.)

[0063]

[Table 6] (9) In the case of oil-extended rubber, the amount of rubber excluding oil (10) Butadiene rubber manufactured by JSR Corporation (11) Diamond black N339 manufactured by Mitsubishi Chemical Corporation (12) Nipsil AQ manufactured by Nippon Silica Co., Ltd. 13) Si69 manufactured by Degussa Co. (14) The same oil used for the oil exhibition, Aromax # 3 manufactured by Fujikosan Co., Ltd. for non-oil exhibition (15) Nocrack manufactured by Ouchi Shinko Chemical Industry Co., Ltd. 810
NA (16) Noxeller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (17) Noxeller D manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (18) CRX2002 manufactured by Cabot Corporation

[0064]

[Table 7]

[0065]

[Table 8]

[0066]

[Table 9]

From the results in Tables 7 and 8, the following is clear. In the case of Examples 1 to 11 using the rubber composition of the present invention of the present invention, it has good processability, does not impair wet skid characteristics (tan δ at 0 ° C. is large), and has low hysteresis loss (50). Tan δ in ° C.
And abrasion resistance are simultaneously balanced to a high level. On the other hand, in the case of Comparative Example 1 using the conjugated diene-based copolymer rubber J synthesized without performing the coupling with the tin compound, the vulcanized product at 50 ° C.
In the case of Comparative Example 2 and Comparative Example 7 in which an an δ was large and no oil-extended rubber was used, the processability was poor. V. of extender oil G. FIG.
C. In the case of Comparative Example 3 in which the
At 0 ° C., tan δ has a large problem. G. FIG.
C. Is less than 0.800, the tan δ at 50 ° C. of the vulcanizate is also large. In the case of Comparative Example 5 using the conjugated diene-based copolymer rubber N synthesized by reducing the coupling with the tin compound, tan δ of the vulcanized product at 50 ° C. is also large. In the case of Comparative Example 6 using no oil-extended rubber, the tan δ of the vulcanized product at 50 ° C. was large. In the case of Comparative Example 8 in which neither silica nor carbon black-silica double phase filler was used, the tan δ of the vulcanized product at 50 ° C. was large and the abrasion resistance was poor. In the case of Comparative Example 9 in which the amount of the copolymer rubber A synthesized in Example 1 as the rubber component was too small, the kneading processability was poor and the abrasion resistance was slightly poor.

[0068]

According to the rubber composition of the present invention, a vulcanizate having good processability, a balance excellent in wet skid properties, low hysteresis loss and excellent abrasion resistance can be obtained. Useful for

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 9/02 C08K 9/02 C08L 9/00 C08L 9/00 F term (Reference) 4J002 AC013 AC063 AC073 AC083 AC093 AC111 AE052 DA036 DE238 DJ017 DJ038 FB097 FB147 FB157 FD016 FD017 FD018 GN01

Claims (3)

[Claims] (A) (A-1) an organolithium and / or
Alternatively, a conjugated diene-based copolymer rubber having a tin content of 50 ppm or more obtained by copolymerizing a conjugated diene compound and a vinyl aromatic compound with a lithium amide compound as an initiator and then reacting with a tin compound as a coupling agent is used. 10
0 parts by weight, and (A-2) viscosity specific gravity constant (VG.
C. (B) an oil-extended rubber containing 5 to 60 parts by weight of an extender oil of 0.800 to 0.950; (B) a diene rubber other than the (A-1) conjugated diene copolymer rubber; -1) Conjugated diene copolymer rubber 10
0 to 300 parts by weight based on 0 parts by weight, (C) carbon black is the total amount of (A-1) conjugated diene copolymer rubber and (B) diene rubber is 100.
(D) silica is used in an amount of 5 to 100 parts by weight, based on 100 parts by weight of the (A-1) conjugated diene copolymer rubber and the (B) diene rubber. 100 parts by weight and 5 to 20 parts by weight of (E) a silane coupling agent based on 100 parts by weight of the silica. (A) a diene rubber other than the (A-1) conjugated diene copolymer rubber is added to the (A-1) conjugated rubber. Diene copolymer rubber 10
0 to 300 parts by weight, and 0 to 300 parts by weight, and (F) the carbon-silica double-phase filler is 100% in total of the above (A-1) conjugated diene copolymer rubber and the above (B) diene rubber. A rubber composition characterized by being mixed in an amount of 1 to 100 parts by weight with respect to parts by weight. 3. A filler other than the (G) carbon-silica double phase filler is used in an amount of 100 parts by weight based on the total amount of the (A-1) conjugated diene copolymer rubber and the (B) diene rubber. 3. The rubber composition according to claim 2, wherein 5 to 100 parts by weight are blended.