JP3327653B2 - Rubber composition and pneumatic tire - Google Patents

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 excellent in breaking characteristics, abrasion resistance and low heat generation, and using the rubber composition. The present invention relates to a pneumatic tire excellent in fuel efficiency and safety.

[0002]

2. Description of the Related Art In recent years, since safety and low fuel consumption are required for automobiles, rubber having low rolling friction resistance, that is, hysteresis loss, excellent in abrasion resistance, fracture characteristics and wet skid resistance is used as a rubber for tire materials. Is desired.

[0003] Therefore, natural rubber, polyisoprene rubber, polybutadiene rubber, or the like, which is known as a rubber material having a small hysteresis loss, is used, but on the other hand, wet skid resistance is not sufficient.

Further, as a synthetic rubber having a remarkably improved low hysteresis loss, there is a polymer obtained by polymerizing an organic lithium compound as an initiator in a hydrocarbon solvent and coupling the terminal of the polymer with a tin halide compound (Japanese Patent Laid-Open Publication No. Sho. 57-55
912). This polymer has excellent physical properties and is used in rubber compositions for tires with low rolling friction and low fuel consumption, but it is satisfactory in terms of wear resistance and fracture characteristics. It can not be said.

On the other hand, as another means for increasing the low hysteresis loss property, a polymer which focuses on a polymer having a molecular structure having a tertiary amine terminal has been developed (Japanese Patent Application Laid-Open No. Sho 50/1985).
-79590, JP-A-52-22484). According to these, a polymer is produced using an alkali metal amide compound such as lithium dipropylamide or a lithium amide compound of a lithium cyclic imide compound such as lithium piperidide as an initiator. However, this polymer is excellent in low hysteresis loss property, but as described above,
It is not sufficient in abrasion resistance and fracture characteristics.

Further, by combining the coupling with a tin compound and the introduction of a tertiary amino group to the terminal of the polymer, not only the low hysteresis loss is improved, but also the workability, tensile strength, abrasion resistance and rebound resilience are improved. However, the level and balance of these properties are not satisfactory with respect to the current requirements.

Another means is to reduce the amount of carbon black to be blended in the above-mentioned polymer and / or to decrease the specific surface area of carbon black, thereby achieving the same effect as the above-mentioned coupling of a tin compound. Low hysteresis loss effect can be obtained. However, it is known that with the reduction of the blending amount of carbon black and the specific surface area, the abrasion resistance and the breaking characteristics are reduced, and the reduction of the specific surface area also reduces the wet skid resistance. I have. From this, a rubber composition having both abrasion resistance and rebound resilience by adjusting various properties of carbon black has been proposed (Japanese Patent Laid-Open No. 3-50 / 1990).
249) has not yet reached a satisfactory level.

Further, in the rubber composition using the above-mentioned polymer, it is difficult to obtain various properties such as low hysteresis loss in a wide range of dynamic strains. Even with a pneumatic tire using the composition, the required properties cannot be sufficiently satisfied.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber composition having excellent breaking characteristics, abrasion resistance and low hysteresis loss without impairing wet skid resistance, and a tire comprising the rubber composition. An object of the present invention is to provide a pneumatic tire which is used for a tread and has excellent fuel efficiency and safety.

[0010]

The rubber composition according to claim 1 comprises a conjugated diene unit or a mixed unit of a conjugated diene unit / vinyl aromatic hydrocarbon unit and has a bound vinyl aromatic hydrocarbon content of 20 to 45. 100 parts by weight of a rubber component containing 30 to 100 parts by weight of a polymer which is a tertiary amine in which at least one terminal of the polymer is a tertiary amine and contains a tin-carbon bond; 150 ml / 100 which is 15 to 45 parts by weight for 100 parts by weight
g of carbon black having a dibutyl phthalate oil absorption (DBP) of at least g.

The rubber composition according to claim 2 is characterized in that, in claim 1, the two polymer terminals of the polymer are tertiary amines.

A third aspect of the rubber composition according to the first or second aspect is that the polymer containing a tin-carbon bond in the polymer is at least 20% by weight of the total polymer.

A pneumatic tire according to claim 4, comprising a conjugated diene unit or a mixed unit of conjugated diene unit / vinyl aromatic hydrocarbon unit and having a bound vinyl aromatic hydrocarbon content of 20 to 45% by weight. Wherein at least one terminal of the polymer is a tertiary amine and 100 to 100 parts by weight of a rubber component containing 30 to 100 parts by weight of the polymer having a tin-carbon bond, and 100 parts by weight of the rubber component And carbon black having a dibutyl phthalate oil absorption (DBP) of 150 ml / 100 g or more, that is, 15 to 45 parts by weight.

In order to solve the above-mentioned problems, the present inventors have focused on the composition and physical properties of the polymer constituting the rubber composition and the colloidal properties of the compounding agent, particularly carbon black, and have conducted extensive studies. Low hysteresis loss (low rolling friction resistance) by blending a specific amount of carbon black having specific physical properties with a polymer having at least one terminal of a tertiary amine and containing a tin-carbon bond. And high abrasion resistance at the same time, and completed the present invention.

That is, in order to remarkably improve the low hysteresis loss property, introduction of a tin-carbon bond into a polymer chain, introduction of a tertiary amino group at a polymer terminal, reduction of the amount of carbon black blended, and the like. In order to improve the fracture characteristics and abrasion resistance even if the amount of carbon black is reduced, and to increase the styrene content in the polymer, for example, By blending the carbon black in a specific amount that does not impair the suitable balance between low hysteresis loss and abrasion resistance, etc., without impairing wet skid resistance, low hysteresis loss, fracture characteristics and abrasion resistance A rubber composition having excellent properties was obtained. In particular, since the rubber composition has a remarkably low hysteresis loss in a wide range of dynamic strain, it can maintain low hysteresis loss even when the situation changes. Furthermore, by using this rubber composition for a tire tread, a pneumatic tire having both low fuel consumption and safety could be obtained.

The following is a detailed description of the present invention. The polymer used in the present invention is a polymer comprising a conjugated diene unit or a mixed unit of a conjugated diene unit / vinyl aromatic hydrocarbon unit and having a vinyl aromatic hydrocarbon unit content of 20 to 45% by weight, At least one polymerized terminal is a tertiary amine and contains a tin-carbon bond. If at least one end is a tertiary amine, the above-mentioned effects can be obtained. However, in order to obtain a more remarkable effect, a multifunctional polymer having two or more polymer terminals with a tertiary amine is preferable, Significant effects can be obtained by 2
Two polymer ends are bifunctional polymers with tertiary amines. Further, the ratio (coupling efficiency) of the polymer containing a tin-carbon bond in the entire polymer is preferably 20% by weight or more from the viewpoint of low hysteresis loss.
0% by weight or more is more preferable.

The content of the vinyl aromatic hydrocarbon in the polymer of the present invention is 20 to 45% by weight, preferably 30 to 4% by weight.
5% by weight. If it is less than 20% by weight, the breaking strength is inferior, and if it exceeds 45% by weight, the hysteresis loss increases, and the glass transition temperature becomes too high, so that the abrasion resistance and low-temperature properties are inferior, which is not preferable. Furthermore, the vinyl bond content in the conjugated diene portion, for example, the butadiene portion of the polymer is 20 to 60% by weight, preferably 40% by weight.
% By weight or less. If it exceeds 60% by weight, the hysteresis loss similarly increases, the glass transition temperature and the modulus of elasticity increase, and the abrasion resistance and low-temperature properties deteriorate.

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

Further, the tertiary amine at the terminal of the polymer, which is a component of the polymer used in the present invention, is a compound in which an amino group such as an amine compound or an amide compound used in the production of the polymer is a tertiary amine. It means the one bonded to the terminal of the union. For example, when a reaction product of a secondary amine and an organic lithium compound or a lithium amide compound is used as a polymerization initiator, these amino groups are bonded to the terminal of the polymer as a tertiary amine. 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 Mooney viscosity of the polymer of the present invention (M
L _{1 + 4} , 100 ° C.) is from 20 to 150, preferably 40
If it is less than 20, the tensile properties and the rebound resilience decrease, which is not preferable. On the other hand, if it exceeds 150, the workability is inferior and it is not preferable.

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

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

The monomer used to obtain the polymer of the present invention is a conjugated diene or a conjugated diene / vinyl aromatic hydrocarbon, and the conjugated diene monomer has 4 to 12 carbon atoms, preferably 4 to 12 carbon atoms per molecule. It is a conjugated diene hydrocarbon containing up to eight. For example, 1,3-butadiene, isoprene, 2,3-dimer-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 preferred.

The vinyl aromatic hydrocarbon monomers include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-butylstyrene,
Vinyl naphthalene and the like are included, with styrene being particularly preferred.

The organic lithium compound includes all generally known compounds, for example, methyl lithium, ethyl lithium, propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexyl lithium, Alkyllithium represented by octyllithium, phenyllithium, tolyllithium, aryllithium represented by lithiumnaphthylide, alkenyllithium represented by vinyllithium, propenyllithium, tetramethylenedilithium, pentamethylenedilithium, Hexamethylene dilithium,
Teolamethylene dilithium, pentamethylene dilithium, hexamethylene dilithium, alkylenedilithium represented by decamethylene dilithium and the like, preferably n-butyllithium and sec.
-Butyllithium. These lithium initiators
They may be used alone or as a mixture of two or more. These lithium compounds can be used in an amount of 0.2 to 30 mmol per 100 g of the monomer.

The secondary amine compound in the amide moiety 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 each represent a hydrocarbon group having 1 to 20 carbon atoms or a hydrocarbon group having an oxygen atom and / or a nitrogen atom, and also include those bonded together to form a ring. Such secondary amine compounds include, for example, 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-methyl imidazolidine, N-ethyl imidazolidine, oxazine, pyrroline, 2,5-dimethyl-3-pyrroline, pyrrole, azepine, 5-pendyloxyindole, 3-azspiro [5,5] undecane, 3-azabicyclo [3,2,2] nonane, carbazole and the like can be mentioned. Among them, dimethylamine, dibutylamine, dihexylamine, butylisopropylamine, trimethyleneimine, pyrrolidine, hexamethyleneimine, dodecamethyleneimine and the like are more preferable.

The addition amount of these secondary amines is 0.01 to 20 molar equivalents, preferably 0.1 to 5.0 molar equivalents, per 1 molar equivalent of the organic lithium compound. When the molar ratio is less than 0.01 molar equivalent, the lithium initiator containing no nitrogen atom becomes the polymerization starting point, and the resulting polymer has a high content of the polymer whose terminal is not a tertiary amine. On the other hand, if it exceeds 20 molar equivalents, the nitrogen atoms not contained in the initiator increase, which is not preferable.

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

In this case, when the reactant of the secondary amine compound and the organolithium compound is used, or when the alcohol and the organolithium are used, the amount of each added is determined by the breaking characteristics, the wear resistance and the low hysteresis. The molar ratio between the secondary amine compound and the organolithium compound is 1: 0.2 to 5.0, preferably 1: 1. The molar ratio is from 1: 0.8 to 5.0, preferably 1: 1.

The alcohols and alcohols in the 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-piperidineethanol, 2-phenyl-
1-piperidineethanol, 2-ethyl-N-β-hydroxyethylmorpholine, 1-piperazineethanol,
1-piperazinepropanol, N, N′-bis (β-hydroxyethyl) piperazine, N, N′-bis (γ-hydroxypropyl) piperazine, 2- (β-hydroxyethyl) pyridine, 2- (γ-hydroxypropyl ) Pyridine and the like, and preferred are tetrahydrofurfuryl alcohol, N, N-dimethylethanolamine, N, N-diethylethanolamine and 1-piperidineethanol.

In the method for producing a polymer, the tin compound may be, for example, tetrachlorotin, tetrabromotin,
Trichlorobutyltin, trichloromethyltin, trichlorooctyltin, dibromodimethyltin, dichlorodimethyltin, dichlorodibutyltin, dichlorotin,
1,2 bis (trichlorostanil) ethane, 1,2 bis (merdichlorostadylethane), 1,4 bis (trichlorostanil) butane, 1,4 bis (methyldichlorostadyl) butane, ethyltin tristea Rate, butyltin trisoctanoate butyltin tristearate, butyltin trislaurate, dibutyltin bisoctanoate, dibutyltin bisstearate, dibutyltin bislaurate, and the like. Dichlorodimethyltin, dibromodimethyltin, dichlorodibutyl, dichlorotin, trichlorobutyltin, trichloromethyltin, tetrachlorotin, tetrabromotin, and the like that can be obtained. Among them, tin from which a bifunctional polymer can be obtained Compounds Preferred. Furthermore, the amount of these silicon compounds added is important in determining the desired number of tertiary amines in the polymer. Assuming that one terminal lithium atom of the polymer and one halogen atom of the silicon compound react stoichiometrically, one mole equivalent of the terminal lithium atom of the polymer having a tertiary amine has a desired number of tertiary amines. The molar equivalent of the silicon compound is added. For example, 0.2 mole of silicon tetrachloride to 1 mole equivalent of polymer terminal lithium atom.
If 5 molar equivalents are added, four polymers of tertiary amine can be obtained, and if 0.125 molar equivalents of silicon tetrachloride or 0.5 molar equivalents of dichlorodimethylsilane are added, tertiary amines become two polymers. Combination can be obtained.
If the molar equivalent of the silicon compound within the range determined stoichiometrically as described above is less than the silicon equivalent contained in the polymer,
Since the content of the polymer having a carbon bond chain is not sufficient, the resulting polymer has poor abrasion resistance and destructive properties, which is not preferable.
On the other hand, if the molar equivalent of the silicon compound is exceeded, the amount of the silicon compound not contained in the polymer increases, which is not preferable.

The polymer containing the tin-carbon bond chain is typically initiated with 1,3-butadiene in the polymerization system so that the living polymer ends with butadienyllithium after the polymerization reaction. 0.1 per mole 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 tin compound.

In order to improve the polymerization activity and / or adjust a desired molecular structure such as molecular weight, microstructure, composition distribution (in the case of a copolymer), etc., according to the purpose of the polymerization reaction system, The usual additives used for the above-mentioned, 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 to be used is 0.05 to 1 mol per mol of the organic lithium compound.
Used in the range of 1000 moles.

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

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

The rubber component of the rubber composition of the present invention includes
Practically, the above-mentioned polymer can be used by blending with natural rubber or other synthetic rubber. In the case of blending, it is necessary to contain the polymer in an amount of 30 parts by weight or more per 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 in the present invention is less than 30 parts by weight, the effect of the above-mentioned polymer cannot be sufficiently exhibited, which is not preferable.

The synthetic rubbers used as blends include cis-1,4-polyisoprene, styrene-butadiene copolymer, low cis-1,4-polybutadiene, high cis-1,4-polybutadiene, ethylene- Propylene-diene copolymer, chloroprene, halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like can be mentioned.

The carbon black used in the rubber composition of the present invention is a so-called high structure carbon black. That is, it is carbon black having a dibutyl phthalate oil absorption (DBP) of 150 ml / 100 g or more, preferably 160 to 200 ml / 100 g.
If the DBP is less than 150 ml / 100 g, the rubber composition of the present invention is inferior in fracture characteristics and abrasion resistance, and is balanced with low hysteresis loss. Also,
The specific surface area is 70 as a nitrogen adsorption specific surface area (N ₂ SA).
１４145 m ² / g are preferred. If the specific surface area is too small, the abrasion resistance and the breaking characteristics are inferior, and the wet skid resistance tends to decrease.

The carbon black having such a high structure is, for example, generally provided coaxially with a cylindrical high temperature combustible fluid for generating a combustion gas and an oxygen-containing gas fluid in an introduction chamber and downstream of the introduction chamber. A cylinder for introducing an oxygen-containing gas having a diameter smaller than that of the cylinder, a plurality of radial rectifying plates provided on an outer periphery of the cylinder, an upstream end connected to the introduction chamber, and gently converging toward the downstream side; A combustion gas converging chamber, a feed oil introducing chamber downstream of the converging chamber, the feed oil introducing chamber having at least one flat surface provided with a plurality of feed oil spraying devices, a downstream end of the feed oil introducing chamber, A reaction chamber having a diameter larger than the diameter of the reaction chamber, a reaction continuation and rapid cooling chamber in which a plurality of cooling water press-in sprayers connected to the reaction chamber and capable of being inserted and withdrawn are installed, and the reaction continuation and rapid cooling chamber. Rear end Using a carbon black manufacturing apparatus entirely covered with refractory and a connected flue portion, the DBP refueling amount is mainly determined by the feed position of the feedstock, that is, the use position of a plurality of feedstock feed planes. Is adjusted, and the base oil is introduced upstream of the converging chamber, that is, at a position close to the introduction chamber, to raise the DBP to a desired value. For N ₂ SA,
It can be done by the ratio of the amount of raw fuel introduced and the amount of air introduced,
The surface area can be increased by increasing the amount of air introduced.

The amount of carbon black in the present invention is from 15 to 45 parts by weight, preferably from 20 to 40 parts by weight, based on the rubber component. If the amount is less than 15 parts by weight, the abrasion resistance and the breaking characteristics of the vulcanized product are not sufficient, and if it exceeds 45 parts by weight, the hysteresis loss is not preferred.

The vulcanizing agent usable in the present invention includes sulfur and the like. The amount of these used is 0.1 to 5 parts by weight, preferably 1 to 2 parts by weight, per 100 parts by weight of the rubber component. is there. If the amount is less than 0.1 part by weight, the fracture characteristics, abrasion resistance and hysteresis loss of the vulcanized rubber are reduced, and if it exceeds 5 parts by weight, the rubber elasticity is lost.

Process oils that can be used in the present invention include:
For example, paraffinic, naphthenic, aromatic and the like can be mentioned. Aromatic type is used in applications where emphasis is placed on fracture characteristics and abrasion resistance, and naphthene type or paraffin type is used in applications where low hysteresis loss and low temperature characteristics are emphasized. On the other hand, the amount is 0 to 100 parts by weight, and if it exceeds 100 parts by weight, the breaking characteristics and low hysteresis loss of the vulcanized rubber are remarkably deteriorated.

The vulcanization accelerator that can be used in the present invention is not particularly limited, but is preferably M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), or CZ (N-cyclohexyl-2). Benzothiazylsulfenamide) and other thiazole-based DPGs
(Diphenylguanidine) and other guadinine-based vulcanization accelerators.
0.1 to 5 parts by weight, preferably 0.2 to 0 parts by weight
３3 parts by weight.

In the present invention, in addition to these, antioxidants usually used in the rubber industry, fillers other than carbon black, such as silica, calcium carbonate and titanium oxide, zinc oxide, stearic acid, antioxidants, Additives such as an ozone deterioration inhibitor can also be blended.

The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll or an internal mixer. After molding, vulcanization is performed to obtain a tire tread, an undertread, a carcass, and a side. It can be used for tires such as walls and beads, as well as anti-vibration rubber, belts, hoses and other industrial products.
Particularly, it is suitably used as a rubber for a tire tread.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention.

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

Various measurements were made according to the following methods. The microstructure of the polymer was determined by an infrared absorption spectrum method (Morello method). The amount of bound styrene was determined by creating a calibration curve by infrared absorption spectroscopy.

The coupling efficiency indicates the ratio of the polymer having a tin-carbon bond in the total polymer, which is determined by gel filtration chromatography (GPC; HL manufactured by Tosoh Corporation).
C-8020, column; determined by the area ratio between the high molecular weight component and the low molecular weight component in the measurement curve by GMH-XL (two in series) manufactured by Tosoh Corporation.

The breaking characteristics were measured according to JIS K-6301. 60 as an index of low hysteresis loss
Tan δ at ° C. was measured and evaluated. tan δ (60
° C) was measured using a dynamic spectrometer manufactured by Rheometrics, Inc., under the conditions of a temperature of 60 ° C, a tensile dynamic strain of 1%, and a frequency of 10 Hz. It was indicated by an index with the value being 100. Therefore, the larger the numerical value is, the smaller the hysteresis loss is, and the better it is. Further, tan δ at 0 ° C. was measured and evaluated as an index of wet skid resistance. tan
δ (0 ° C.) was measured using the same instrument under the conditions of a temperature of 0 ° C., a dynamic tensile strain of 0.1%, and a frequency of 10 Hz, and was represented by an index with the value in Comparative Example 8 being 100. The higher the numerical value, the higher the wet skid resistance and the better.

The wear resistance was measured by using a Lambourn type abrasion tester and measuring the amount of wear at a slip rate of 25% at room temperature.
Using the value of the reciprocal, the value was represented by an index with the value in Comparative Example 8 being 100. The higher the value, the better the wear resistance.

Example 1 In a 300 ml pressure bottle, 25 g of cyclohexane, 3.7 mmol of lithium diethylaminoethoxide as a lithium alkoxide, 7.4 mmol of di-n-butylamine as a secondary amine compound,
And n-butyllithium 7.4 mm which is an organic lithium
ol were 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, 240 g of styrene, and
324 g of 1,3-butadiene, 1.
68 g were charged. After adjusting the polymerization start temperature to 60 ° C,
The polymerization was carried out by adding the whole amount of the initiator solution. When the polymerization addition rate reaches 100%, 1,3-butadiene 3
After adding 6 g to make the polymer terminal be butadienyl lithium, 1.03 g (3.38 mmol) of dibutyldichlorotin was added as a coupling agent and reacted for 10 minutes.

After 2,6-di-t-butyl-p-cresol was added to the polymer-containing solution, the solvent was removed by steam stripping, and the polymer was dried with a hot roll at 110 ° C. To a tertiary amine [(n-C ₄ H
₉₎ to obtain a polymer A which is the rubber-like polymer having ₂ N-]. The properties of the polymer A are shown in Table 1.

Polymer A was prepared according to the formulation shown in Table 3 together with the carbon black a shown in Table 2 according to the formulation shown in Table 3.
Kneading and blending were performed using a 0 ml Labo Plastomill and a 3 inch roll. The obtained polymer A was blended with natural rubber (NR) and polymer A at a blend ratio of 30 each.
It was blended as parts by weight and 70 parts by weight. After vulcanizing the compounded rubber at 145 ° C. for 30 minutes, the physical properties of the vulcanized product were evaluated, and the results are shown in Table 4.

Example 2 In Example 2, a polymer B and a vulcanized product thereof were obtained in the same manner as in Example 1 except that the following initiator was used. Tables 1 and 4 show the properties of the polymer B and the physical properties of the obtained vulcanizate.

The initiator used for the polymer B was di-n-butylamine as a secondary amine compound at 7.4 mmol.
1, n-butyllithium 7.4 mm as organic lithium
ol, except that 3.7 mmol of lithium-t-ethoxide was used as the lithium alkoxide.

Example 3 In Example 3, 0.39 g of tetrachlorotin was used instead of dibutyldichlorotin (1.
50 mmol) in the same manner as in Example 1 except that
A polymer C having a tertiary amine at the four terminals of the polymer and a vulcanized product thereof were obtained. The properties of the polymer C and the physical properties of the obtained vulcanized product are shown in Tables 1 and 4.

Example 4 Example 4 was carried out in the same manner as in Example 1 except that the blend ratio of the natural rubber and the polymer A was changed to 60 parts by weight and 40 parts by weight, respectively. . Table 4 shows the physical properties of the obtained vulcanized product.

Example 5 Example 5 was carried out in the same manner as in Example 1 except that carbon black b was used instead of carbon black a. Table 4 shows the physical properties of the obtained vulcanized product.

Example 6 Example 6 was carried out in the same manner as in Example 1 except that the amount of carbon black was changed to the amount shown in Table 4. Table 4 shows the physical properties of the obtained vulcanized product.

Comparative Example 1 In Comparative Example 1, n was used as an initiator.
Polymer D and a vulcanizate thereof were obtained in the same manner as in Example 1 except that only -butyllithium was used and no secondary amine compound and lithium alkoxide were used. This polymer D is a polymer having no tertiary amine at the polymer terminal. Tables 1 and 4 show the properties of the polymer D and the physical properties of the obtained vulcanized product.

Comparative Example 2 In Comparative Example 2, n was used as an initiator.
Using only butyllithium and 0.39 g (1.50 m) of tetrachlorotin instead of dibutyldichlorotin
mol), and E and its vulcanizate were obtained in the same manner as in Example 1. This polymer E is a polymer having no tertiary amine at the polymer terminal. Tables 1 and 4 show the properties of the polymer E and the physical properties of the obtained vulcanized product.

Comparative Examples 3 and 4 Comparative Examples 3 and 4 were carried out in the same manner as in Example 1 except that the amounts of carbon black were changed to 50 parts by weight and 10 parts by weight, respectively. Table 4 shows the physical properties of the obtained vulcanized product.

Comparative Example 5 Comparative Example 5 was carried out in the same manner as in Example 1 except that carbon black was used instead of carbon black a. Table 4 shows the physical properties of the obtained vulcanized product.

Comparative Example 6 Comparative Example 6 was carried out in the same manner as in Example 1 except that the carbon black to be blended was changed to c instead of carbon black a, and the blending amount was changed to 50 parts by weight. Table 4 shows the physical properties of the obtained vulcanized product.

Comparative Example 7 Comparative Example 7 was performed in the same manner as in Example 1 except that the blend ratio of the natural rubber compounded as the rubber component and the polymer A was 80 parts by weight and 20 parts by weight, respectively. went. Table 4 shows the physical properties of the obtained vulcanized product.

Comparative Example 8 Comparative Example 8 was conducted in the same manner as in Example 1 except that polymer D was used instead of polymer A, c was used instead of carbon black a, and the blending amount was 50 parts by weight. The same was done. Table 4 shows the physical properties of the obtained vulcanized product.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

[Table 3]

[0072]

[Table 4]

As shown in Table 4, the rubber composition of the present invention was a rubber composition excellent in breaking characteristics, abrasion resistance and low hysteresis loss without impairing wet skid resistance.

In Examples of the present invention, polymers A and B were prepared by using a tin coupling agent with an initiator using a secondary amine compound, an organic lithium compound and a lithium alkoxide.
And C are styrene-butadiene random copolymers having a high styrene content and having a tertiary amino group at the polymerization terminal and containing a tin-carbon bond. By using these copolymers, the tan δ (0 ° C.), ie, the breaking characteristic, tan δ (60 ° C.) without impairing the wet skid resistance.
That is, the low hysteresis loss property and the Lambourn abrasion index, that is, the abrasion resistance, were significantly improved (Examples 1 to 6).

Further, this effect can be obtained by using the type of initiator (Examples 1, 2 and 3) and the type of tin compound as a coupling agent (Examples 1 and 3) in the polymer, and the carbon black having a high structure. Irrespective of the type (Examples 1 and 5), and the blend ratio of the copolymer in the rubber component is 30% by weight or more (Example 1).
And 4) and that the compounding amount of the carbon black was 15 parts by weight or more (Example 6 and the like).

It has been clearly recognized that such a remarkable effect cannot be obtained unless the polymer has the above-mentioned molecular structure (Comparative Examples 1 and 2).

Further, even when the copolymer is used, if the blending ratio in the rubber component is less than 30% by weight, not only various physical properties are deteriorated, but also wet skid resistance cannot be maintained, and the balance of the balance cannot be maintained. A removed rubber composition was not obtained (Comparative Example 7). Similarly, even if the copolymer is used, if the high-structure carbon black of the present invention is not used, the fracture characteristics and abrasion resistance are significantly impaired (Comparative Example 5). It was also confirmed that when the amount was increased, the low hysteresis loss property was impaired (Comparative Example 6).

In addition, even when carbon black having a high structure is used, a large amount of carbon black significantly impairs the low hysteresis loss property (Comparative Example 3), while a small amount significantly impairs the breaking characteristics and abrasion resistance (Comparative Example 3). Example 4) also became clear.

[0079]

As described above, the present invention provides a rubber composition having excellent breaking characteristics, abrasion resistance and low hysteresis loss (rolling friction resistance) without impairing wet skid resistance. The use of this rubber composition for a tire tread has an excellent effect that a pneumatic tire excellent in fuel efficiency and safety can be provided.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08F 8/42 C08F 8/42 (56) References JP-A-64-70541 (JP, A) JP-A-62-215639 (JP, A) JP-A-5-186639 (JP, A) JP-A-61-81445 (JP, A) JP-A-63-118343 (JP, A) JP-A-1-193341 (JP, A) JP-A-62-161844 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 9/00-9/10 C08K 3/04

Claims (4)

(57) [Claims] 1. A polymer comprising a conjugated diene unit or a mixed unit of conjugated diene unit / vinyl aromatic hydrocarbon unit and having a bound vinyl aromatic hydrocarbon content of 20 to 45% by weight. The polymer containing at least one tertiary amine and containing a tin-carbon bond,
100 parts by weight of a rubber component containing 100 parts by weight, and carbon black having a dibutyl phthalate oil absorption (DBP) of 150 ml / 100 g or more, which is 15 to 45 parts by weight with respect to 100 parts by weight of the rubber component. A rubber composition characterized by the following: 2. The rubber composition according to claim 1, wherein two polymer terminals of the polymer are tertiary amines. 3. The rubber composition according to claim 1, wherein the amount of the tin-carbon bond-containing polymer in the polymer is 20% by weight or more of the whole polymer. 4. A polymer comprising a conjugated diene unit or a mixed unit of conjugated diene unit / vinyl aromatic hydrocarbon unit and having a bound vinyl aromatic hydrocarbon content of 20 to 45% by weight, The polymer containing at least one tertiary amine and containing a tin-carbon bond,
A rubber composition comprising: 100 parts by weight of a rubber component containing 100 parts by weight; and carbon black having a dibutyl phthalate oil absorption (DBP) of 150 ml / 100 g or more, which is 15 to 45 parts by weight based on 100 parts by weight of the rubber component. A pneumatic tire using a material.