JPH07188468A - Rubber composition and pneumatic tire - Google Patents

Abstract

PURPOSE:To obtain a rubber compsn. excellent in rupture characteristics, abrasion resistance, and grip by compounding a specific rubber component with a specific carbon black and a softener, and to obtain a high-performance pneumatic tire excellent in grip and durability by using the compsn. CONSTITUTION:A rubber compsn. with a hardness of 55 deg. or higher is obtd. by compounding 100 pts.wt. rubber component with 50-150 pts.wt. fine-particle carbon black with a nitrogen-adsorption specific surface area (N2SA) of 110m<2>/g or higher and at least 30 pts.wt. softener (e.g. an arom. process oil or a liq. styrene-butadiene rubber). The rubber component contains at least 30 pts.wt. polymer which comprises conjugated diene units or their mixture with arom. vinyl hydrocarbon units, has at least one molecular terminal with a tert. amino group, contains Si-C bonds, and has a wt.-average mol.wt. of 60X10<4> or higher and a glass transition point of -50 deg.C to -6 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition and a pneumatic tire, and more particularly to a rubber composition for a tire tread and a high performance pneumatic tire using the same.

[0002]

2. Description of the Related Art In recent years, tire tread rubber, especially high-performance tire tread rubber, has a high level of wear resistance, fracture characteristics, wet grip characteristics on wet road surfaces (wet skid resistance) and dry grip characteristics. There is a strong demand for a comprehensive balance in.

In response to such demands, these performances are associated with the rubber composition, and in order to improve grip characteristics, the hysteresis loss of the tread rubber composition is increased, that is, in terms of viscoelasticity. It has been found that it is necessary to increase tan δ, and that it is effective to add a large amount of extending oil or the like. It has also been found that in order to improve wear resistance and high-speed durability, it is necessary to increase tensile strength, particularly tensile strength at high temperature (100 ° C.) and fracture characteristics such as elongation at break.

Conventionally, various rubber polymer compositions have been developed for the purpose of satisfying the above-mentioned various properties.
Examples of these include styrene-butadiene copolymer and various rubbers, for example, butyl rubber in JP-B-60-51501, JP-A-62-143945, and JP-A-6-143945.
No. 142842 discloses polynorbornene in JP-A-63-63.
-132949 has a blend of polyisoprene rubber, and as an example of using additives and softeners, coumarone indene resin is used.
No. 1735 etc. are mentioned. Furthermore, new butadiene
Examples of the use of styrene copolymers include butadiene-styrene copolymers whose terminals are modified with a diphenylmethanol-based compound of JP-A-60-61314 and styrene-butadiene copolymers of JP-A-1-131258. A diblock butadiene-styrene copolymer composed of two block copolymer parts having different composition ratios may be mentioned.

However, the above-mentioned rubber composition can sufficiently satisfy the actually required high levels of wear resistance, fracture characteristics and grip characteristics, and the balance of these characteristics at a high level. It has not reached the realm.

Furthermore, adding a large amount of a softening agent, etc.
Although the grip characteristics can be increased, the breaking characteristics and wear resistance may be impaired.

On the other hand, as a means for improving wear resistance,
It is also practiced to reduce the particle size of carbon black to be blended, but as the particle size decreases, the dispersibility becomes poor, and with this, the wear resistance becomes poor. Up to that point, improvement in wear resistance will reach a ceiling. Further, by reducing the particle size, the hysteresis loss of the rubber composition decreases,
It is recognized that the grip characteristics are inferior.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rubber composition having excellent breaking properties and abrasion resistance, and high gripping properties, and by using this rubber composition, grip performance is improved. And to provide a high performance pneumatic tire having excellent durability.

[0009]

The rubber composition according to claim 1 is a polymer comprising a conjugated diene unit or a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit, and at least one polymer terminal. Is a tertiary amine and 100 parts by weight of a rubber component containing 30 parts by weight or more of a polymer containing a silicon-carbon bond, and 100 parts by weight of the rubber component,
50 to 150 parts by weight and the nitrogen adsorption specific surface area (N ₂
SA) is 110 m ² / g or more, carbon black, and 100 parts by weight of the rubber component, and 30 parts by weight or more of a softening agent are characterized by being included.

A rubber composition according to a second aspect is the rubber composition according to the first aspect, wherein the four polymer terminals of the polymer are tertiary amines.

A rubber composition according to a third aspect is the rubber composition according to the first or second aspect, wherein the polymer contained in the rubber component is a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit. , At least one polymer terminal is a tertiary amine and is a polymer containing a silicon-carbon bond.

A rubber composition according to a fourth aspect is characterized in that, in the third aspect, the polymer is a polymer having a vinyl aromatic hydrocarbon unit content of 25 to 50% by weight.

The rubber composition according to claim 5 is the rubber composition according to claim 1,
In 2 or 3, the polymer containing a silicon-carbon bond in the polymer is 20% by weight or more of the total polymer.

The pneumatic tire according to claim 6 is a polymer comprising a conjugated diene unit or a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit, and at least one polymer terminal is a tertiary amine. Further, 100 parts by weight of a rubber component containing 30 parts by weight or more of a polymer containing a silicon-carbon bond, and 50 to 150 parts by weight with respect to 100 parts by weight of the rubber component.
And the nitrogen adsorption specific surface area (N ₂ SA) is 11 parts by weight.
A rubber composition containing carbon black of 0 m ² / g or more and a softening agent of 30 parts by weight or more based on 100 parts by weight of the rubber component is used.

A pneumatic tire according to claim 7 is characterized in that, in claim 6, the rubber composition is a rubber composition having a hardness of 55 degrees or more.

In order to solve the above-mentioned problems, the present inventors have paid attention to the composition of the polymer constituting the rubber composition and its physical properties, as well as the colloidal properties of the compounding agent, especially carbon black, and the influence of the softening agent. As a result of investigation, abrasion resistance and fracture characteristics were obtained by adding a specific amount of carbon black having specific physical properties to a polymer having at least one terminal of a tertiary amine and containing a silicon-carbon bond. The inventors have found that it is possible to achieve both high grip performance and high grip performance, and have completed the present invention.

That is, in the polymer, silicon in the polymer
The carbon bond is a strong bond unlike the tin-carbon bond, and the bond is less likely to be broken by a physical action such as kneading.Therefore, by using the polymer containing the silicon-carbon bond chain, the polymer is The reinforcing property of the rubber composition containing the rubber composition can be improved, and therefore, the breaking property and wear resistance of the rubber composition can be improved. Further, in order to improve the reinforcing effect of carbon black, it has been carried out to reduce the particle size of carbon black,
Dispersion failure due to the formation of fine particles, which has been a problem in the past, can be solved by blending a specific amount of a softening agent that does not impair grip properties and introducing a tertiary amino group at the polymer terminal. did it. The tertiary amine at the end of the polymer acts on the carbon black, so that the dispersibility of the carbon black can be assisted, and the tertiary amine itself also has a reinforcing effect. Even if it is made small, the dispersibility does not decrease, and the wear resistance can be improved as the particles become finer. Therefore, it is possible to improve wear resistance and fracture characteristics without impairing grip performance, and by using this rubber composition for a tire tread, a high-performance pneumatic tire having both high grip performance and safety can be obtained. I was able to get it.

The present invention will be described in detail below. The polymer used in the present invention is a polymer composed of a conjugated diene unit or a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit, wherein at least one polymerization end is a tertiary amine and a silicon-carbon bond. It is a polymer containing. If at least one end is a tertiary amine, the above-mentioned effects can be obtained, but in order to obtain a more remarkable effect, a polyfunctional polymer having two or more polymer terminals as a tertiary amine is preferable, and It is the tetrafunctional polymer in which four polymer ends are tertiary amines that give a significant effect. In addition, the ratio of the polymer containing a silicon-carbon bond (coupling efficiency) to the total polymer is preferably 20% by weight or more, and more preferably 50% by weight or more, from the viewpoint of wear resistance and fracture characteristics. .

The content of vinyl aromatic hydrocarbon units in the polymer of the present invention is 25 to 50% by weight, preferably 30.
~ 45% by weight. If it is less than 25% by weight, the breaking strength is inferior, which is not preferable, and if it exceeds 50% by weight, the glass transition temperature becomes too high and the abrasion resistance and the low temperature characteristics are inferior. Furthermore, the vinyl bond content in the conjugated diene part such as butadiene part of the above polymer is 15 to 50% by weight. If it exceeds 50% by weight, the glass transition temperature and elastic modulus are increased, and the abrasion resistance and low temperature characteristics are deteriorated, which is not preferable, and if it is less than 15% by weight, the heat resistance is deteriorated, which is not preferable.

The conjugated diene unit or the mixed unit of conjugated diene unit / vinyl aromatic hydrocarbon unit, which is a constituent element of the polymer used in the present invention, is the conjugated diene monomer or the conjugated diene monomer used in the production of the polymer, respectively. / Means a unit obtained by polymerizing a mixture of vinyl aromatic hydrocarbon monomers.

The tertiary amine at the end of the polymer, which is a constituent of the polymer used in the present invention, has a heavy amine compound such as an amine compound or an amide compound used in the production of the polymer in the form of a tertiary amine. It means the one bound to the end of the united body. For example, when a reaction product of a secondary amine and an organic lithium compound or a lithium amide compound was used as a polymerization initiator, these amino groups were obtained as a tertiary amine because they were bonded to the end of the polymer. The amino group of the tertiary amine of the polymer is the same as the amino group of the compound used as the initiator.

The weight average molecular weight of the polymer of the present invention is 60 × 10 ⁴ or more, preferably 70 × 10 ⁴ or more. When it is less than 60 × 10 ⁴ , tensile properties and impact resilience are deteriorated, which is not preferable.

Further, the glass transition temperature (T
_g ) is −50 to −6 ° C., preferably −40 to −
It is 20 ° C. This T _g can be adjusted by the microstructure of the polymer and the physical properties and amount of various compounding agents. If this T _g is less than −50 ° C., the grip properties will be poor, and if it is −6 ° C. or higher, the fracture properties and wear resistance will be poor, and this is not preferred.

In order to obtain such a polymer of the present invention, various production methods are used. For example, after polymerizing the above monomer in a hydrocarbon solvent using a reaction product of a secondary amine compound and an organolithium compound or a lithium amide compound as an initiator, and optionally in the presence of an ether or a tertiary amine compound. There is a method of causing a coupling reaction with a silicon compound. Hereinafter, an exemplary production method for obtaining the polymer of the present invention will be described.

Examples of usable hydrocarbon solvents are aromatic hydrocarbon solvents such as benzene, toluene and xylene, n-pentane, n-hexane, n-butane and n-.
Aliphatic hydrocarbon solvents such as heptane and octane, alicyclic hydrocarbon solvents such as methylcyclopentane and cyclohexane, and mixtures thereof can be used.

The monomers used to obtain the polymers of this invention are conjugated dienes or conjugated diene / vinyl aromatic hydrocarbons, which have from 4 to 12 carbon atoms per molecule, preferably 4 carbon atoms. It is a conjugated diene hydrocarbon containing ~ 8. For example, 1,3-butadiene, isoprene, 2,3-dimel-1,3-butadiene, 1,3-pentadiene, octadiene and the like can be mentioned. These may be used alone or in combination of two or more, and 1,3-butadiene is particularly preferable.

The vinyl aromatic hydrocarbon includes styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-butylstyrene, vinylnaphthalene and the like, and particularly styrene. preferable.

Organolithium compounds include all commonly known compounds such as methyllithium, ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexyllithium, Alkyl lithium typified by octyl lithium, phenyl lithium, tolyl lithium, aryl lithium typified by lithium naphthylide, vinyl lithium, alkenyl lithium typified by propenyl lithium, tetramethylene dilithium, pentamethylene dilithium, Hexamethylenedilithium,
Examples include alkylenedilithium typified by theoramethylenedilithium, pentamethylenedilithium, hexamethylenedilithium, decamethylenedilithium and the like, but preferably n-butyllithium and sec
-Butyl lithium. These lithium initiators are
They may be used alone or in combination of two or more. The amount of these lithium compounds used can be in the range of 0.2 to 30 mmol per 100 g of the monomer.

The secondary amine compound in the amide portion of the secondary amine compound or amide compound used in the method for producing the polymer can be represented by the general formula R ¹ R ² NH,
Here, R ¹ and R ² represent a hydrocarbon group having 1 to 20 carbon atoms or a hydrocarbon group having an oxygen atom and / or a nitrogen atom, and both include those which are bonded to each other to form a ring. Examples of the secondary amine compound as described above include dimethylamine, diethylamine, dipropylamine, dibutylamine, diisobutylamine, dipentylamine,
Dihexylamine, diheptylamine, dioctylamine, diallylamine, dicyclohexylamine, butylisopropylamine, dibenzylamine, methylbenzylamine, methylhexylamine, ethylhexylamine, trimethyleneimine, pyrrolidine, 2,5-dimethylpyrrolidine, piperidine, 2 -Methylpiperidine, 3
-Methylpiperidine, 4-methylpiperidine, 3,3-
Dimethylpiperidine, 2,6-dimethylpiperidine,
3,5-dimethylpiperidine, 2-ethylpiperidine,
1-methyl-4- (methylamine) piperidine, 2,
2,6,6-Tetramethylpiperidine, hexamethyleneimine, heptamethyleneimine, morpholine, piperazine, 2,6-dimethylmorpholine, 2,6-dimethylpiperazine, 2-methylpiperazine, N-methylpiperazine, N-ethylpiperazine , 1-benzylpiperazine,
N-methylimidazolidine, N-ethylimidazolidine, oxazine, pyrroline, 2,5-dimethyl-3-pyrroline, pyrrole, azepine, 5-pentyloxyindole, 3-azuspiro [5,5] undecane, 3-azabicyclo Examples include [3,2,2] nonane and carbazole. Among these, dimethylamine, dibutylamine, dihexylamine, butylisopropylamine, trimethyleneimine, pyrrolidine, hexamethyleneimine, dodecamethyleneimine and the like are more preferable.

The amount of these secondary amines added is 0.01 to 20 molar equivalents, preferably 0.1 to 5.0 molar equivalents, relative to 1 molar equivalent of the organolithium compound. When the amount is less than 0.01 molar equivalent, the lithium initiator not containing a nitrogen atom serves as a polymerization initiation point, and the content of the polymer having a polymer terminal other than a tertiary amine in the obtained polymer is high. The dispersibility and the reinforcing effect of the carbon black are deteriorated and the abrasion resistance is poor, which is not preferable. On the other hand, when it exceeds 20 molar equivalents, the number of nitrogen atoms not contained in the initiator increases, which is not preferable.

Further, as an initiator, in addition to the reaction product of the secondary amine compound and the organic lithium compound or the lithium amide compound, a method of using an alcohol and an organic lithium or lithium alkoxide in combination is also preferably used.

In this case, when the reaction product of the secondary amine compound and the organolithium compound is used, and when the alcohol and the organolithium are used, the addition amount of each is such that the physical properties such as fracture characteristics, abrasion resistance and the like. Is determined in consideration of
The molar ratio of the secondary amine compound and the organolithium compound is
1: 0.2 to 5.0, preferably 1: 1 and the molar ratio of alcohol to organolithium is 1: 0.8 to 5.
It is 0, preferably 1: 1.

The above alcohols and alcohols in lithium alkoxide include t-butanol, sec-butanol, cyclohexanol, octanol, 2-ethylhexanol, p-cresol, m-cresol,
Nonylphenol, hexylphenol, tetrahydrofurfuryl alcohol, furfuryl alcohol, 3-ethyl-tetrahydrofurfuryl alcohol, oligomers of tetrahydrofurfuryl alcohol, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether, N, N-dimethylethanolamine,
N, N-diethylethanolamine, N, N-dibutylethanolamine, N, N-diphenylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, N-phenyldiethanolamine, N, N-dimethylpropanol Amine, N, N-dibutylpropanolamine, N
-Methyldipropanolamine, N-ethyldipropanolamine, 1- (2-hydroxyethyl) pyrrolidine, 2-methyl-1- (2-hydroxyethyl) pyrrolidine, 2-methyl-1- (3-hydroxypropyl) pyrrolidine , 1-piperidine ethanol, 2-phenyl-
1-piperidine ethanol, 2-ethyl-N-β-hydroxyethylmorpholine, 1-piperazine ethanol,
1-piperazine propanol, N, N'-bis (β-hydroxyethyl) piperazine, N, N'-bis (γ-hydroxypropyl) piperazine, 2- (β-hydroxyethyl) pyridine, 2- (γ-hydroxypropyl) ) Pyridine and the like can be mentioned, but tetrahydrofurfuryl alcohol, N, N-dimethylethanolamine, N, N-diethylethanolamine and 1-piperidineethanol are preferable.

The silicon compound in the method for producing the polymer is, for example, silicon tetrachloride, silicon tetrabromide, trichlorobutylsilane, trichloromethylsilane, trichlorooctylsilane, dibromodimethylsilane, dichlorodimethylsilane, dichlorodibutylsilane, Dichlorosilane, chlorotriethylsilane, chlorotriphenylsilane, dichlorodimethylsilane and the like can be mentioned, but preferably dibromodimethylsilane, dichloroditylsilane, dichlorosilane, which can obtain a bifunctional or higher functional polymer. Trictotobutylsilane, trichloromethylsilane, silicon tetrachloride, silicon tetrabromide, and the like, and among these, a silicon compound that can obtain a tetrafunctional polymer is most preferable. Furthermore, the amount of these silicon compounds added is important in determining the desired number of tertiary amines in the polymer. Polymer-terminated lithium atom having a tertiary amine, assuming that one polymer-terminated lithium atom and one halogen atom of a silicon compound react stoichiometrically
A molar equivalent of a silicon compound corresponding to the desired number of tertiary amines is added to the molar equivalent. For example, by adding 0.25 molar equivalent of silicon tetrachloride to 1 molar equivalent of a polymer terminal lithium atom, a polymer having four tertiary amines can be obtained, and 0.125 molar equivalent of silicon tetrachloride or By adding 0.5 molar equivalent of dichlorodimethylsilane, it is possible to obtain a polymer having two tertiary amines. As described above, when the amount is less than the molar equivalent of the silicon compound within the stoichiometrically determined range, the content of the silicon-carbon bond chain-containing polymer contained in the polymer is not sufficient, so that the resistance of the obtained polymer is low. Abrasion resistance and fracture characteristics are inferior, which is not preferable. On the other hand, if the molar equivalent of the silicon compound is exceeded, the amount of silicon compound not contained in the polymer increases, which is not preferable.

Polymers selectively containing a silicon-carbon bond chain are typically initiated with 1,3-butadiene in the polymerization system after the polymerization reaction so that the living polymer ends are butadienyllithium. 0.1 mol per mol equivalent of lithium atom of the agent.
It is obtained by adding 5 to 100 mol, preferably 1 to 20 mol, and then reacting with a silicon compound.

Further, a softening agent is essential to the present invention, and after the completion of the reaction of the polymer, a softening agent is added in a necessary amount in part or in whole, and the softening agent is removed by a direct drying method or a steam strip method. Solvent drying (masterbatch) can also be performed. The softening agent will be described later.

For the purpose of adjusting the desired molecular structure such as molecular weight, microstructure, composition distribution (in the case of copolymer) depending on the purpose of improving the polymerization activity and / or the purpose of use in the polymerization reaction system of the polymer, The usual additives used for the above, for example, Lewis bases such as ether compounds and tertiary amine compounds can be added. The amount of the ether compound and the tertiary amine compound used is 0.05 to 1 mol of the organic lithium compound.
It is used in the range of 1000 mol.

The polymerization temperature and the reaction with the silicon compound are usually carried out in the range of -20 to 150 ° C, preferably 0 to 120 ° C, and may be under elevated temperature conditions or elevated temperature conditions. The polymerization method may be either a batch polymerization method or a continuous polymerization method.

The above-described method for producing a polymer in the present invention is an example, and the present invention is not limited to this.

As the rubber component of the rubber composition of the present invention,
Practically, the above polymer and natural rubber or other synthetic rubber can be blended and used. In the case of blending, it is necessary to add 30 parts by weight or more to 100 parts by weight of the rubber component, and preferably 50 parts by weight or more. For example, in a blend with natural rubber, if the amount of the polymer of the present invention is less than 30 parts by weight, the effects of the above-mentioned polymer cannot be sufficiently exhibited, which is not preferable.

The synthetic rubbers to be blended and used include cis-1,4-polyisoprene, styrene-butadiene copolymer, low cis-1,4-polybutadiene, high cis-1,4-polybutadiene, ethylene- Examples thereof include propylene-diene copolymer, chloroprene, halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like.

The carbon black used in the rubber composition of the present invention is a carbon black fine particles is preferably 110m ² / g or more of a nitrogen adsorption specific surface area (N ₂ SA), this value is, 110m ² / If it is less than g, the breaking property, the wear resistance and the grip property are deteriorated, which is not preferable.

The amount of carbon black used in the present invention is 50 to 150 parts by weight based on the rubber component.
It is preferably 60 to 100 parts by weight. If it is less than 50 parts by weight, the vulcanizate has insufficient wear resistance and fracture properties,
Further, if it exceeds 150 parts by weight, abrasion resistance and the like are not preferable.

It is essential to add a softening agent to the rubber composition of the present invention, and even if the softening agent is added after the polymerization reaction of the polymer, other additions are made to the obtained polymer. The effect of the present invention can also be obtained by blending with an agent. The softener includes process oil and liquid polymer, and either one of them or a mixture of both can be added. The final blending amount as a softening agent is 30 parts by weight or more, preferably 30 to 200 parts by weight, based on 100 parts by weight of the rubber component. If this amount is less than 30 parts by weight, grip properties and workability are poor, which is not preferable.

Examples of the process oil in the present invention include paraffin type oil, naphthene type oil, aromatic type oil and the like. An aromatic type is particularly used for applications where importance is attached to fracture characteristics and wear resistance. The blending amount of the process oil is determined by the amount of the liquid polymer mixed together as a softening agent, the blending amount of other blending agent, and the like, and is 30 to 120 parts by weight with respect to 100 parts by weight of the rubber component. preferable.

On the other hand, the liquid polymer in the present invention includes a low molecular weight conjugated diene polymer and a conjugated polymer having a weight average molecular weight of 0.5 × 10 ⁴ to 10 × 10 ⁴ , preferably 1 × 10 ^{4 to} 7 × 10 ^4. Diene / vinyl aromatic hydrocarbon copolymers are included, and the content of bound vinyl aromatic hydrocarbon units in the case of copolymers is less than 50% by weight, preferably 10-4.
One of them is 0% by weight. Weight average molecular weight is 0.5
When it is less than × 10 ⁴ , the breaking property is inferior, while when it exceeds 10 × 10 ⁴ , the hardness is high and the grip property is inferior, which is not preferable. It is not preferable because it has high hardness and poor grip characteristics. Examples of these include liquid polybutadiene rubber, liquid polyisoprene rubber, liquid styrene-butadiene rubber, and the like.
Butadiene rubber is preferred. The amount of the liquid polymer is determined by the amount of the process oil to be blended and the amount of the other compounding agent, similar to the process oil, but is 20 to 100 parts by weight with respect to 100 parts by weight of the rubber component. Is preferred.

Examples of the vulcanizing agent that can be used in the present invention include sulfur and the like. The amount of these is 0.1 to 5 parts by weight, preferably 1 to 2 parts by weight, based on 100 parts by weight of the rubber component. is there. If it is less than 0.1 parts by weight, the tensile strength and wear resistance of the vulcanized rubber will decrease, and if it exceeds 5 parts by weight, rubber elasticity will be lost.

The vulcanization accelerator that can be used in the present invention is not particularly limited, but preferably M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2). -Benzothiazylsulfenamide) and other thiazole-based DPGs
Examples of the vulcanization accelerator include guadinine-based vulcanization accelerators such as (diphenylguanidine).
0.1 to 5 parts by weight, preferably 0.2
~ 3 parts by weight.

In the present invention, in addition to these, antioxidants which are usually used in the rubber industry, fillers other than carbon black such as silica, calcium carbonate, titanium oxide, zinc oxide, stearic acid, antioxidants, Additives such as antiozonants may also be added.

The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll or an internal mixer. After the molding process, vulcanization is performed to obtain a tire tread, an undertread, a carcass and a side. It can be used not only for tires such as walls and beads, but also for applications such as anti-vibration rubber, belts, hoses and other industrial products.
Particularly, it is preferably used as rubber for tire tread.

[0051]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

In the examples, parts and% mean parts by weight and% by weight unless otherwise specified.

Various measurements were made by the following methods. The microstructure of the polymer was determined by the infrared absorption spectrum method (Morero method). The amount of bound styrene was obtained by preparing a calibration curve by the infrared absorption spectrum method.

Coupling efficiency is a ratio of a polymer having a silicon-carbon bond to the total polymer, which is a gel filtration chromatography (GPC; H of Tosoh Corp.).
LC-8020, column; Tohso's GMH-XL (two in series) was determined from the area ratio of the high molecular weight component and the low molecular weight component in the measurement curve.

The breaking characteristics were measured according to JIS K-6301. Hardness (HD) is JIS K-6301
The hardness was measured by a spring hardness meter at 25 ° C.

The abrasion resistance was measured by using a Lambourn type abrasion tester and measuring the amount of abrasion at a slip ratio of 25% at room temperature.
Using the reciprocal value, the value in Comparative Example 4 was displayed as an index with the value being 100. Therefore, the larger the value, the better the wear resistance.

The grip characteristics are hysteresis loss characteristics and wet skid resistance as a rubber composition, and
The wet grip performance and dry grip performance of the tire were evaluated as indexes.

The hysteresis loss characteristic is ta at 30 ° C.
nδ was measured and evaluated. For tan δ (30 ° C.), a dynamic spectrometer manufactured by Rheometrics Inc. in the US is used,
The measurement was performed under the conditions of a temperature of 30 ° C., a tensile dynamic strain of 1%, and a frequency of 10 Hz, and the value was expressed as an index with the value in Comparative Example 4 being 100. The wet skid resistance is t at 0 ° C.
An δ was measured and evaluated. The tan δ (0 ° C.) was measured using the same equipment under the conditions of temperature 0 ° C., dynamic tensile strain 0.1% and frequency 10 Hz, and the value in Comparative Example 4 was 100.
Was displayed as an index. In both cases, the larger the numerical value, the greater the rolling friction resistance and the wet skid resistance, and the higher the grip property, the better.

The wet grip and dry grip are
Using the rubber composition used in this example as a rubber composition for a tire tread, a 16.5SR13 tire was prepared and evaluated using this tire. Wet grip is 40k / h on wet asphalt road
Sudden braking was applied from the respective speeds of m, 70 km, and 100 km, and the running distance until the vehicle completely stopped was determined, and the value of the reciprocal thereof was used and displayed as an index with the value in Comparative Example 4 as 100. Therefore, the larger the value, the shorter the distance to complete stop and the better the wet grip performance. The dry grip was measured on a clear day on a circuit running lap time composed of a straight road, a curve, a bank, and the like, and the reciprocal value was used to display the dry grip as an index with the time in Comparative Example 4 as 100. Therefore, the larger the value, the shorter the lap time and the better the dry grip performance.

Example 1 25 g of cyclohexane, 3.7 mmol of lithium diethylaminoethoxide which is a lithium alkoxide, 7.4 mmol of di-n-butylamine which is a secondary amine compound, in a 300 ml pressure resistant bottle.
And n-butyllithium that is organic lithium 7.4 mm
ol was added in this order and reacted at 27 ° C. for 15 minutes,
37 mmol of 1,3-butadiene was added, and the mixture was further reacted for 15 minutes to prepare an initiator.

Next, 200 g of cyclohexane and 240 g of styrene were placed in a reactor having an internal volume of 5 liters which had been purged with nitrogen.
1,3-butadiene 324 g, tetrahydrofuran 1.
68g was charged. After adjusting the polymerization initiation temperature to 60 ° C,
Polymerization was carried out by adding all of the above initiator solution. When the polymerization addition rate reached 100%, 1,3-butadiene 3
After 6 g was added to make the polymer terminal into butadienyl lithium, 0.39 g (1.50 mmol) of silicon tetrachloride
Was added and reacted for 10 minutes.

After adding 2,6-di-t-butyl-p-cresol to the polymer-containing liquid, 37.5 parts by weight of aroma oil was added as a softening agent, and the solvent was removed by steam stripping. The oil masterbatch polymer A (hereinafter referred to as a polymer A (M)), which is a rubber-like polymer, is dried by drying with a 110 ° C. hot roll. That is, a polymer oil-extended with a softening agent that is a process oil or a liquid polymer. X is referred to as a polymer X (M)). Polymer A (M)
The characteristics of are shown in Table 1.

The polymer A (M) was used according to the formulation shown in Table 3 together with carbon black a shown in Table 2 and 22.5 parts by weight of the additional aroma oil (60 parts by weight of the total aroma oil). 250 ml lab plastomill and 3
Kneading and blending was performed with an inch roll. Compound rubber at 145 ° C
After vulcanizing for 30 minutes, the physical properties of the vulcanized product were evaluated, and the results are shown in Table 4.

Example 2 Example 2 was carried out in the same manner as in Example 1 except that the polymer B having a higher vinyl content in the butadiene portion than the polymer A used in Example 1 was used. The properties of the polymer B (M) and the physical properties of the obtained vulcanizate are shown in Tables 1 and 4
It was shown to.

Example 3 In Example 3, a low molecular weight styrene-butadiene copolymer (butadiene part vinyl content 6) was used as a softening agent in the masterbatch instead of aromatic oil.
0% by weight, styrene content 25% by weight, molecular weight 1 × 10 ⁴ ;
Hereinafter, polymer C (M) and its vulcanized product were obtained in the same manner as in Example 1 except that 40 parts by weight of low molecular weight SBR) was added and 20.0 parts by weight of aroma oil was added. Polymer C
The properties of (M) and the physical properties of the vulcanizates obtained are shown in Tables 1 and 4.

Example 4 In Example 4, the polymer D (M) was prepared in the same manner as in Example 1 except that the following initiator and softener were used, and the aroma oil was 20.0 parts by weight. And a vulcanized product thereof were obtained. The properties of the polymer D (M) and the physical properties of the obtained vulcanizate are shown in Tables 1 and 4.

The initiator used in the polymer D was di-n-butylamine as a secondary amine compound at 7.4 mmo.
l, n-butyllithium 7.4 mm as organic lithium
was prepared in the same manner as the initiator of the polymer A, except that 3.7 mmol of lithium-t-ethoxide was used as the lithium alkoxide and lithium alkoxide. As the softening agent in the masterbatch, 40 parts by weight of low molecular weight SBR was used instead of aroma oil.

Example 5 In Example 5, the polymer A (M) was used.
The compounding amount of 82.5 parts by weight (rubber component: 60 parts by weight) instead of 100 parts by weight, and the high aroma oil-extended SBR # 1721 (oil compounding ratio: 37.5 parts by weight) is 55.0 parts by weight.
The same procedure as in Example 1 was performed except that the addition of parts by weight (rubber component: 40 parts by weight) was added. The physical properties of the obtained vulcanizate are shown in Table 4.

Example 6 In Example 6, the polymer C (M) was used.
Which is 84 parts by weight (rubber component: 60 parts by weight) instead of 100 parts by weight, which is a highly aromatic oil-extended SBR # 1.
721 was added in the same manner as in Example 1 except that 55.0 parts by weight (rubber component: 40 parts by weight) was added and the aroma oil was changed to 21.0 parts by weight. The physical properties of the obtained vulcanizate are shown in Table 4.

Example 7 Example 7 was performed in the same manner as in Example 1 except that the carbon black to be blended was b instead of carbon black a in Table 2. The physical properties of the obtained vulcanizate are shown in Table 4.

Example 8 In Example 8, the polymer A (M) was used.
Was used as Polymer C (M), and carbon black to be blended was changed to b instead of carbon black a in Table 2, and the same procedure as in Example 1 was carried out. The physical properties of the obtained vulcanizate are shown in Table 4.

Example 9 Example 9 was carried out in accordance with Example 1 except that the amount of aroma oil was 32.5 parts by weight. The physical properties of the obtained vulcanizate are shown in Table 4.

Example 10 Example 10 was carried out in accordance with Example 3 except that the amount of aroma oil was 30 parts by weight. The physical properties of the obtained vulcanizate are shown in Table 4.

Comparative Example 1 Comparative Example 1 was prepared in the same manner as in Example 1 except that the polymer obtained had a high bound styrene content and a high T _g. A vulcanized product was obtained. The properties of the polymer E (M) and the physical properties of the obtained vulcanizate are shown in Tables 1 and 4.

Comparative Example 2 Comparative Example 2 was prepared according to Example 1 except that the polymer obtained had a lower bound styrene content and a lower T _g , and the polymer F (M) and its addition were obtained. A sulfide was obtained. The properties of the polymer F (M) and the physical properties of the obtained vulcanizate are shown in Tables 1 and 4.

[Comparative Example 3] In Comparative Example 3, a polymer G (M) and a vulcanized product thereof were obtained in the same manner as in Example 1 except that the coupling efficiency of the silicon compound was low. Polymer G (M)
The properties and physical properties of the vulcanizate obtained are shown in Table 4.

Comparative Example 4 In Comparative Example 4, n was used as the initiator.
Example 1 except that only -butyllithium was used and no secondary amine compound and lithium alkoxide were used.
Polymer H (M) and its vulcanized product were obtained in the same manner as in.
The properties of the polymer H (M) and the physical properties of the obtained vulcanizate are shown in Table 1.
And 4 are shown.

Comparative Example 5 In Comparative Example 5, polymer I (M) and its vulcanized product were obtained in the same manner as in Example 1 except that silicon tetrachloride was not coupled. Polymer I
The properties of (M) and the physical properties of the vulcanizate obtained are shown in Table 4.

Comparative Example 6 Comparative Example 6 was performed in the same manner as in Example 1 except that the carbon black to be blended was c instead of carbon black a in Table 2. The physical properties of the obtained vulcanizate are shown in Table 4.

Comparative Example 7 In Comparative Example 7, the compounding amount of the polymer A was 27.5 parts by weight (rubber component: 20 parts by weight), and
Example 1 was repeated except that the amount of 1721 blended was 110 parts by weight (rubber component: 80 parts by weight). The physical properties of the obtained vulcanizate are shown in Table 4.

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[Table 1]

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[Table 2]

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[Table 3]

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[Table 4]

As shown in Table 4, the rubber composition of the present invention was shown to be an excellent rubber composition capable of improving wear resistance and fracture characteristics without impairing grip characteristics.

In the examples of the present invention, the polymers A, B, C and D prepared by using an initiator containing a secondary amine compound, an organolithium compound and a lithium alkoxide and a silicon compound are each a tertiary amino group at the end of the polymer. And a styrene-butadiene random copolymer having a silicon-carbon bond chain. Tan δ (30 ° C.) and tan δ can be obtained by blending the copolymer, particulate carbon black included in the scope of the present invention, and a softening agent in specific amounts.
It was shown that the fracture characteristics and wear resistance were improved without impairing the hysteresis loss characteristics evaluated by (0 ° C.), that is, the grip characteristics (Examples 1 to 4). Also,
If the effect is within the scope of the present invention, the type of the initiator in the polymer (Examples 1 and 4), the type of the particulate carbon black (Examples 1 and 3 and Examples 7 and 8) and the softening agent It can be obtained regardless of the total amount of addition (Examples 1 and 9 and Examples 3 and 10), and the above polymer is blended with a general-purpose oil-extended styrene-butadiene copolymer # 1721 in a predetermined ratio. It was also clarified that the wear resistance and fracture properties of the obtained rubber composition can be improved by using the rubber component described above (Examples 5 and 6).

It was clearly recognized that such a remarkable effect can be obtained only by the polymer having the above-mentioned molecular structure (Comparative Examples 4 and 5).

Even if a polymer having the above structure is used,
If the T _{g of the} polymer is too high, the wear resistance and fracture properties and the wet grip performance and dry grip performance of the tire are significantly deteriorated (Comparative Example 1), while if the T _g is too low, the grip properties are significantly deteriorated (comparison). Example 2), and if the coupling efficiency of the silicon compound is too low, the fracture characteristics and wear resistance decrease (Comparative Example 3),
Further, when the ratio of the polymer in the rubber component is less than 30 parts by weight, the fracture properties and the wear resistance are inferior (Comparative Example 7),
It was confirmed that the effect cannot be obtained at all (Comparative Example 6) unless the carbon black to be blended is fine carbon black having predetermined characteristics.

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EFFECTS OF THE INVENTION Since the present invention has the above-mentioned constitution, it is possible to provide a rubber composition having excellent breaking characteristics and abrasion resistance and having high grip performance. By using this rubber composition for a tire tread. A high performance pneumatic tire having excellent grip performance and durability can be provided.

Claims (7)

[Claims] 1. A polymer comprising a conjugated diene unit or a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit, wherein at least one polymer end is a tertiary amine and a heavy chain containing a silicon-carbon bond. 100 parts by weight of a rubber component containing 30 parts by weight or more of the coalesce, and 50 to 150 parts by weight and a nitrogen adsorption specific surface area (N ₂ SA) of 110 m ^{2 with} respect to 100 parts by weight of the rubber component.
/ G or more of carbon black, and a rubber composition containing 30 parts by weight or more of a softening agent with respect to 100 parts by weight of the rubber component. 2. The rubber composition according to claim 1, wherein the four polymer terminals of the polymer are tertiary amines. 3. The polymer contained in the rubber component is a polymer composed of a conjugated diene unit / vinyl aromatic hydrocarbon unit mixed unit, and at least one polymer terminal is a tertiary amine and silicon. -The rubber composition according to claim 1 or 2, which is a polymer having a carbon bond. 4. The rubber composition according to claim 3, wherein the polymer is a polymer having a vinyl aromatic hydrocarbon unit content of 25 to 50% by weight. 5. The rubber composition according to claim 1, 2 or 3, wherein the polymer containing a silicon-carbon bond is 20% by weight or more of the total polymer. 6. A polymer comprising a conjugated diene unit or a mixed unit of a conjugated diene unit / a vinyl aromatic hydrocarbon unit, wherein at least one polymer end is a tertiary amine and a heavy chain containing a silicon-carbon bond. 100 parts by weight of a rubber component containing 30 parts by weight or more of the coalesce, and 50 to 150 parts by weight and a nitrogen adsorption specific surface area (N ₂ SA) of 110 m ^{2 with} respect to 100 parts by weight of the rubber component.
A pneumatic tire comprising a rubber composition containing carbon black of not less than 10 g / g and a softening agent of not less than 30 parts by weight with respect to 100 parts by weight of the rubber component. 7. The pneumatic tire according to claim 6, wherein the rubber composition is a rubber composition having a hardness of 55 degrees or more.