JPH09124844A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition excellent in low rolling resistance and wet skid properties and a pneumatic tire using the rubber composition. SOLUTION: This rubber composition is obtained by blending 10 pts.wt. of a conjugated diene-based rubber such as a butadiene-styrene copolymer rubber or a natural rubber with 30-120 pts.wt. of carbon black having both characteristics of [=C=O functional group concentration]/N2 SA>=4.0×10<-4> and [=C=O functional group concentration] >= [-OH functional group concentration]<2> -0.1[-OH functional group concentration] +0.03 [=C=O functional group concentration] is the concentration of a functional group (meq/g) to form an oxime by reaction with a hydroxylamine, N2 SA is a specific surface area of nitrogen absorption (m<2> /mg) and [-OH functional group concentration] is a concentration of a functional group to be acetylated with acetic anhydride}. The pneumatic tire uses this rubber composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition,
More specifically, it relates to a rubber composition having extremely low hysteresis loss and a high level of wet skid. The present invention also relates to a pneumatic tire using this rubber composition for a tire tread, and more specifically to a pneumatic tire having significantly improved low rolling resistance performance (fuel economy) and excellent wet skid performance.

[0002]

2. Description of the Related Art In recent years, along with the demand for safety and low fuel consumption for automobiles, good wet skid properties and low hysteresis loss properties (and low tire rolling resistance performance, low tire resistance performance) have been achieved in rubber materials for tires. It is strongly demanded that fuel efficiency is satisfied at the same time. It is generally known that these two characteristics have an antinomy relationship. That is, when the low hysteresis loss property (low rolling resistance performance) is set, the wet skid property is deteriorated, and when the wet skid property is improved, the low hysteresis loss property is deteriorated.

In the prior art, in order to solve the above problems,
Improvements in rubber compositions for tires have been made from both sides of polymer type and carbon black type.

Focusing on the improvement of the rubber composition by the carbon black system, many techniques are known as exemplified below. In an example of increasing the particle size of carbon black, it is known that the rubber composition has a low hysteresis loss property, but the wet skid property is deteriorated. Only the surface chemical properties of carbon black and the effect of the rubber composition for tires (and by extension the pneumatic tire using the same) will be described, but in JP-A-64-20246, the concentration and pH of all acidic groups are mainly described. A rubber composition having improved exothermic properties and reinforcing properties at high temperatures using carbon black whose value is specified; in JP-A-2-105836, carbon black mainly specified in the number of oxygen-containing functional groups is used. And a rubber composition having excellent wet skid characteristics, rolling friction resistance, and reinforcement at high temperature;
No. 837 discloses a rubber composition which mainly uses carbon black whose oxygen-containing functional group concentration is specified and which is excellent in rolling friction resistance and reinforcement at high temperature;
In Japanese Patent Publication No. 144, rolling resistance and abrasion resistance are mainly used by using carbon black whose relationship with the amount of functional groups that undergo acetylation reaction with acetic anhydride and the amount of functional groups that react with hydroxylamine to form oximes is specified. In JP-A-4-189845, carbon black having a specified concentration of -OH functional group which reacts with acetylation with acetic anhydride is mainly used, and it has excellent rolling friction resistance and reinforcement at high temperature. Rubber composition;
No. 25472, a rubber composition using mainly oxidized carbon black and having excellent low rolling resistance and traction characteristics; JP-A No. 6-107863 discloses a quinone group concentration in NaOH and a quinone group concentration in NaOH. A rubber composition and the like having excellent reinforcing properties are disclosed by using carbon black whose total acidity determined by the Japanese method is specified.

[0005]

However, in these prior arts, the rubber composition containing carbon black having the characteristic surface chemical properties as described above, a modified rubber in some cases, and various compounding agents in some cases is used in the present invention. Although many aim to achieve different purposes, some attempts have been made to achieve the same purpose as the present invention, but they cannot be said to be sufficient. That is, the low hysteresis loss property (low rolling resistance performance) is remarkably improved,
At the same time, there is no known rubber composition or pneumatic tire that satisfies a high level of wet skid properties.

Therefore, an object of the present invention is to provide a rubber composition excellent in low hysteresis loss property and wet skid property. Another object of the present invention is to provide a pneumatic tire having improved low rolling resistance performance and wet skid performance at the same time.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have made diligent studies by paying attention to the chemical structure, chemical properties, physical properties of the carbon black surface, and the molecular structure of the rubber raw material. As a result, they have found that the above-mentioned required characteristics can be satisfied at the same time by using a specific carbon black different from the conventional one, by the following means, and have completed the present invention. (1) The rubber composition of the present invention is represented by the following formula (I) and formula (II) with respect to 100 parts by weight of at least one rubber selected from the group consisting of conjugated diene synthetic rubber and natural rubber. 30 to 12 carbon black having both characteristics
It is characterized by containing 0 part by weight.

Formula (I)

[0009]

(Equation 5)

Formula (II)

[0011]

(Equation 6)

[In the formula, [> C═O functional group concentration] represents the functional group concentration (meq / g) which reacts with hydroxylamine to form an oxime, and N ₂ SA represents the nitrogen adsorption specific surface area (m ² / m ² ). mg), and [-OH functional group concentration] represents the functional group concentration (meq / g) that undergoes acetylation reaction with acetic anhydride.) (2) The rubber composition of the present invention is the same as the above (1), The conjugated diene-based synthetic rubber is polybutadiene rubber and / or styrene-butadiene rubber. (3) The rubber composition of the present invention is characterized in that, in the above item (1), the conjugated diene-based synthetic rubber is a rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group. To do. (4) In the rubber composition of the present invention, the functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group in the conjugated diene-based synthetic rubber is polybutadiene rubber and / or styrene-butadiene. It is characterized in that it is a rubber contained in rubber. (5) In the rubber composition of the present invention, in the above (1), at least one selected from the group consisting of furnace black and channel-type carbon black is oxidized by an oxidizing means. It is characterized by being carbon black obtained by applying. (6) In the rubber composition of the present invention, in the above (1), at least one selected from the group consisting of furnace black and channel type carbon black is oxidized by an oxidizing means. Further, it is characterized in that it is a carbon black obtained by heat treatment at a temperature of 100 to 900 ° C. (7) The pneumatic tire of the present invention is a pneumatic tire including a tread portion, a sidewall portion, and a bead portion, wherein the tread portion is at least one selected from the group consisting of conjugated diene-based synthetic rubber and natural rubber. Rubber 100
The rubber composition is characterized by using 30 to 120 parts by weight of carbon black having both characteristics represented by the following formula (I) and formula (II) with respect to parts by weight.

Formula (I)

[0014]

(Equation 7)

Formula (II)

[0016]

(Equation 8)

[In the formula, [> C = O functional group concentration] represents the functional group concentration (meq / g) which reacts with hydroxylamine to form an oxime, and N ₂ SA represents the nitrogen adsorption specific surface area (m ² / mg), and [-OH functional group concentration] represents the functional group concentration (meq / g) that undergoes acetylation reaction with acetic anhydride.) (8) The pneumatic tire of the present invention is the same as in (7) above. The conjugated diene-based synthetic rubber is polybutadiene rubber and / or styrene-butadiene rubber. (9) The pneumatic tire of the present invention is characterized in that in the above (7), the conjugated diene-based synthetic rubber is a rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group. To do. (10) In the pneumatic tire of the present invention, in the above (7), the conjugated diene-based synthetic rubber has a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group as polybutadiene rubber and / or styrene-butadiene. It is characterized in that it is a rubber contained in rubber. (11) In the pneumatic tire of the present invention, in the above (7), at least one selected from the group consisting of furnace black and channel type carbon black is oxidized by an oxidizing means. It is characterized by being carbon black obtained by applying. (12) In the pneumatic tire of the present invention, according to the item (7), at least one selected from the group consisting of furnace black and channel type carbon black is oxidized by an oxidizing means, Further, it is characterized in that it is a carbon black obtained by heat treatment at a temperature of 100 to 900 ° C.

It is essential that the carbon black compounded in the rubber composition of the present invention satisfies two characteristics. 2
The two characteristics are [> C = O functional group concentration] / N ₂ SA ≧
4.0 × 10 ⁻⁴ (hereinafter referred to as X characteristic) and [> C═O functional group concentration] ≧ [—OH functional group concentration] ² −
0.1 * [-OH functional group concentration] +0.03 (hereinafter referred to as Y characteristic). Various functional groups are present on the surface of carbon black, and as described above, in the prior art, carbon black is specified by using various parameters based on these functional groups. In the present invention, the carbon black specified by the X characteristic and the Y characteristic related to the> C = O functional group concentration and / or the -OH functional group concentration is used.
This is a new spec of carbon black that has never been known. The X characteristic represents the required amount of> C = O functional group concentration, and the Y characteristic represents the relative concentration difference between> C = O functional group and -OH functional group. By using carbon black satisfying both the X characteristic and the Y characteristic, the rubber composition exhibits the effects of low hysteresis loss and wet skid for the first time. It is difficult to achieve compatibility of the effects even if either of the characteristics of carbon black is lacking. If the carbon black is less than 4.0 × 10 ⁻⁴ in the X characteristic and does not satisfy the inequality in the Y characteristic, a sufficient effect cannot be obtained.

The carbon black used in the present invention may be a commercially available product, a commercially available product treated or a newly manufactured product, as long as it has both the X characteristic and the Y characteristic. Although not particularly limited, for example, (1) gas furnace black, (2) channel type carbon black, (3) furnace black (including oil furnace black and gas furnace black) or channel type carbon black is used. HNO ₃ , H ₂ O ₂ , O ₃ , those subjected to oxidation treatment by an oxidizing means such as dichromate, and (4) gas furnace black or channel-type carbon black was heat-treated at a temperature of 100 to 900 ° C. Things, (5)
The carbon black subjected to the oxidation treatment of (3) above may be further subjected to a heat treatment at a temperature of 100 to 900 ° C. Among them, the carbon blacks (3) and (5) are preferable from the viewpoint of the effect.

The amount of carbon black used in the rubber composition of the present invention is 30 to 1 with respect to 100 parts by weight of rubber.
20 parts by weight, preferably 35 to 100 parts by weight, 3
If it is less than 0 parts by weight, a rubber composition having a sufficient elastic modulus cannot be obtained and the reinforcing property cannot be secured, and if it exceeds 120 parts by weight, sufficient carbon dispersion cannot be obtained and the reinforcing property is deteriorated, which is not preferable.

The rubber used in the rubber composition of the present invention is at least one rubber selected from the group consisting of conjugated diene synthetic rubber and natural rubber.

The conjugated diene-based synthetic rubber includes (1) a rubber obtained by polymerizing a conjugated diene monomer, (2) a rubber obtained by copolymerizing a conjugated diene monomer and a vinyl aromatic hydrocarbon monomer, and (3) A rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group at the end of the conjugated diene rubber at (1) or the end of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber at (2) is included. . Above all, the rubber having the tin-containing group or the nitrogen-containing group of the above (3) at the rubber end is preferable from the viewpoint of improving the low hysteresis loss property and the wet skid property. These synthetic rubbers may be used alone or in combination of two or more. Further, these synthetic rubbers are preferably used as a blend with natural rubber. In this case, the weight ratio of synthetic rubber / natural rubber is about 90/10 to 30/70.

Examples of the conjugated diene monomer include 1,
3-butadiene, isoprene, 2,3-dimethyl-1,
3-Butadiene, 1,3-pentadiene, 1,3-hexadiene and the like, and mixtures thereof are included, among which 1,3-butadiene or isoprene is preferable. Preferred conjugated diene rubbers are high cis-1,4-polybutadiene, low cis-1,4-polybutadiene, high cis-1,
4-polyisoprene can be mentioned.

The vinyl aromatic hydrocarbon monomer includes styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, t-butylstyrene and the like, among which styrene is preferred. Preferred conjugated diene / vinyl aromatic hydrocarbon copolymer rubbers include styrene-butadiene rubber.

The microstructure of a conjugated diene / vinyl aromatic hydrocarbon co-heavy rubber, for example, styrene-butadiene rubber, may have a composition distribution of random type, block type or intermediate type, but is preferably random type. ,
The amount of vinyl in the butadiene part may be in the range obtained by polymerization with a lithium compound initiator system, and is usually 20 to 80%.
The styrene / butadiene weight ratio is usually in the range of 10/90 to 60/40.

The conjugated diene rubber and the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber can be easily obtained by polymerizing or copolymerizing a predetermined amount of the above-mentioned monomer with, for example, an organic lithium compound as an initiator. The organolithium compound includes all generally known compounds and is not particularly limited, and examples thereof include methyllithium, ethyllithium, propyllithium, n-butyllithium, sec.
-Alkyl lithium typified by butyl thylium, tert-butyl lithium, hexyl lithium, octyl lithium, etc., Aryl lithium typified by phenyl lithium, tolyl lithium, lithium naphthylide, alkenyl lithium typified by vinyl lithium, propenyl lithium, etc. , Alkylenedilithium represented by tetramethylenedilithium, pentamethylenedilithium, hexamethylenedilithium, heptamethylenedilithium, decamethylenedilithium, and the like.

The amount of organolithium compound is determined depending on the desired molecular weight of the rubber, but is generally 100% monomer.
With respect to g, 0.05 to 15 mmol, preferably 0.1
-10 mmol is used. If it exceeds 15 mmol, it is difficult to obtain a high molecular weight compound,
If it is less than the above range, it may be inactivated by impurities in the polymerization system and the polymerization may not proceed, which is not preferable.

In the conjugated diene rubber or the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber in the rubber composition of the present invention, a randomizer is preferably used when it is desired to obtain a rubber having a desired molecular structure. The term "randomizer" as used herein refers to control of the microstructure of the rubber, such as the increase of 1,2 bonds in the butadiene part of polybutadiene or styrene-butadiene rubber, and the composition of the monomer units of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber. It is a compound having a function of controlling distribution, for example, randomizing butadiene units and styrene units of styrene-butadiene rubber.

The randomizer is not particularly limited, but includes all commonly used randomizers. Examples of the randomizer used include ethers such as tetrahydrofuran (THF), tetrahydropyran, 1,4-dioxane, monoglycol methyl ether (monoglyme), diglycol methyl ether (diglyme), triglycol methyl ether (triglyme). , And oligomeric oxolanyl alkane compounds such as bis (2-oxolanyl) methane, 2,2-bis (2-oxolanyl) propane, 1,1-bis (2-oxolanyl) ethane, 2,2-bis (5 -, methyl-2-oxolanyl) propane, further tertiary amine compounds such as triethylamine, tripropylamine, ^{tributylamine, N, N, N ',} N' - tetramethylethylenediamine (TMEDA), dipiperidinoethane etc. Included .

The randomizer is used in an amount of 0.01 to 1000 mol per mol of the organic lithium compound.

The polymerization can be carried out at any temperature within the range of about -80 to 150 ° C, but a temperature of -20 to 100 ° C is preferred. The polymerization reaction can be carried out under a generated pressure, but it is usually desirable to operate at a pressure sufficient to keep the monomer substantially in the liquid phase. That is, the pressure depends on the individual substance to be polymerized, the diluent used and the polymerization temperature,
Higher pressures can be used if desired, and such pressures are obtained in any suitable manner such as pressurizing the reactor with a gas inert to the polymerization reaction.

As the polymerization system, either bulk polymerization or solution polymerization can be adopted, but it is preferable to use solution polymerization in an inert solvent. Normally, the solvent is preferably a liquid under the conditions of the polymerization reaction, and an aliphatic, alicyclic or aromatic hydrocarbon is used. Examples of preferred inert solvents include propane, butane, pentane, hexane, heptane, isooctane, cyclopentane, cyclohexane, methylcyclohexane, decane, benzene, toluene, xylene,
Examples thereof include naphthalene and tetrahydronaphthalene.
You may use these solvents as a mixture of 2 or more types.
In general, it is preferred to remove water, oxygen, carbon dioxide and other catalyst poisons from all materials involved in the polymerization process such as initiator components, solvents, monomers.

The rubber having a tin-containing group at the end of the conjugated diene rubber or the end of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber used in the rubber composition of the present invention includes:
(1) As described above, the tin-containing compound is added to the terminal active lithium of the conjugated diene rubber or the terminal active lithium of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber obtained by polymerizing a monomer with, for example, an organolithium compound initiator. The rubber obtained by the reaction, (2) using a tin-containing initiator,
The rubber obtained by polymerization of the conjugated diene monomer or copolymerization of the conjugated diene monomer / vinyl aromatic hydrocarbon monomer can be mentioned in the same manner as the above-mentioned organolithium initiator.

The tin-containing compound has the following general formula: Sn R ¹ pXq or R ¹ pSn- (OCO-R ² ) _4- p (wherein R ¹ and R ² are an alkyl group, an alkenyl group,
Substituents selected from the group consisting of cycloalkyl groups and aryl groups, which may be the same or different, X is a halogen atom, p is an integer of 0 to 3, and p + q.
= 4), chlorine or bromine is preferably used as the halogen atom of X, and R is
The alkyl group and alkenyl group of ¹ and R ² are preferably those having 1 to 20 carbon atoms, and the cycloalkyl group and aryl group are preferably those having 6 to 20 carbon atoms.

Specifically, the tin halide compound represented by the general formula SnR ¹ pXq is tetrachlorotin, tetrabromotin, methyltrichlorotin, butyltrichlorotin, octyltrichlorotin, phenyltrichlorotin, phenyl. Tribromotin, tolyltrichlorotin, dimethyldichlorotin, dimethyldibromotin, diethyldichlorotin, dibutyldichlorotin,
Dioctyldichlorotin, diphenyldichlorotin, diallyldichlorotin, dibutenyldichlorotin, tributylmonochloross and the like can be mentioned.

The above general formula R ¹ pSn- (OCO-
Examples of the tin carboxylate compound represented by R ² ) _4- p include methyltin tris stearate, ethyl tin tris stearate, butyl tin tris octanoate, butyl tin tris stearate, octyl tin tris stearate, and butyl tin trislaurate. Rate, dibutyl tin bis octanoate, dibutyl tin bis stearate, dibutyl tin bis laurate, dimethyl tin bis stearate, diethyl tin bis laurate, dioctyl tin bis stearate, trimethyl tin laurate,
Trimethyltin stearate, tributyltin octanoate, tributyltin stearate, tributyltin laurate, trioctyltin stearate, phenyltin tristearate, phenyltin trisoctanoate, phenyltin trislaurate, diphenyltin bisstearate, diphenyltin bis stearate Octanoate, diphenyl tin bislaurate, triphenyl tin stearate, triphenyl tin octanoate, triphenyl tin laurate, cyclohexyl tin tris stearate, dicyclohexyl tin bis stearate,
Examples thereof include tricyclohexyltin stearate, tributyltin acetate, dibutyltin bisacetate, butyltin trisacetate and the like.

The reaction between the tin-containing compound and the rubber active terminal lithium is usually at 30 to 120 ° C. for 0.5 minutes to 1
It can be performed under the condition of time range.

The amount of the tin-containing compound used is in the range of 0.4 to 1.5 molar equivalent based on the halogen atom in the case of the tin halide compound, per 1 molar equivalent of active terminal lithium. In the case of a tin carboxylate compound, the carboxyl group is 0.2 to 3.0 per mol of lithium.
It is used in a molar equivalent, preferably 0.4 to 1.5 molar equivalent. If the amount of the tin halide compound is less than 0.4 molar equivalent and the amount of the tin carboxylate compound is less than 0.2 molar equivalent, the low stericis loss property of the vulcanized rubber obtained is inferior, and the tin halide is less. If the amount of the compound exceeds 1.5 molar equivalents, or if the amount of the tin carboxylate compound exceeds 3.0 molar equivalents, a gel polymer is produced,
The vulcanized product is also inferior in low hysteresis loss property.

The tin-containing initiator can be obtained, for example, by reacting lithium metal with an organotin halogen compound having the general formula R ³ ₃ SnX. In the formula, R ³ has an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 7 to 20 carbon atoms. It is selected from the group consisting of aralkyl groups. Typical alkyl groups include n-butyl, sec-butyl, methyl, ethyl, isopropyl and the like. The cycloalkyl group includes
Includes cyclohexyl, menthyl and the like. The aryl group and aralkyl group include phenyl, benzyl and the like. In the formula, X is preferably a chlorine atom or a bromine atom.

[0040] As another tin-containing initiator, such as lithium metal and tin - organotin compounds include tin bond R ⁴ ₃ SnSnR ⁴ ₃ (wherein, R ⁴ has the same meaning as R ³⁾ and Is obtained by reacting. The preferred organotin compound has 6 to 120 carbon atoms and is, for example, hexabutylditin.

As the tin-containing initiator, R ³ ₃ S obtained by reacting lithium metal with an organotin halogen compound is used.
nLi (in the formula, R ³ is as described above) is preferable, and examples thereof include tributyltin lithium.

The rubber having a nitrogen-containing group at the end of the conjugated diene rubber or the end of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber used in the rubber composition of the present invention is (1)
As described above, for example, to the terminal active lithium of the conjugated diene rubber or the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber obtained by polymerizing the monomer with an organolithium compound initiator, an isocyanate compound, a dialkylamino-substituted aromatic compound or A rubber obtained by reacting an aromatic heteronitrogen-containing compound, (2) using a lithium amide initiator prepared in advance or prepared in situ in the presence of a monomer, with an organolithium initiator as described above Similarly, a rubber obtained by polymerization of the conjugated diene monomer or copolymerization of the conjugated diene monomer / vinyl aromatic hydrocarbon monomer can be mentioned.

As the isocyanate compound, 2,4-
Tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolidine diisocyanate, triphenylmethane triisocyanate, p-phenylene diisocyanate, tris (isocyanatophenyl)
Thiophosphate, xylylene diisocyanate, benzene-1,2,4-triisocyanate, naphthalene-
1,2,5,7-tetraisocyanate, naphthalene-
1,3,7-triisocyanate, phenyl isocyanate, hexamethylene diisocyanate, methylcyclohexane diisocyanate and the like can be mentioned. Preferably, aromatic diisocyanate or triisocyanate or an aromatic isocyanate compound such as a dimer, a trimer of various aromatic isocyanate compounds and an adduct obtained by reacting the aromatic isocyanate with a polyol or a polyamine is used. Used. More preferably, aromatic polyisocyanate compounds such as 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate are used.

Examples of the dialkylamino-substituted aromatic compound include N, N'-dimethylaminobenzophenone, N,
N'-diethylaminobenzophenone, N-dimethylaminobenzaldehyde, N-diethylaminobenzaldehyde, N-dimethylaminobenzoyl chloride, N
-Methyl ester of dimethylaminobenzoic acid, p-diethylaminostyrene, p-dimethylaminostyrene, p
-Dimethylaminomethylstyrene, 1- (N-dimethylamino) -4-chlorobenzene and the like.

As the aromatic hetero nitrogen-containing compound, 4-
Vinyl pyridine, 2-vinyl pyridine, bis (2-pyridyl) ketone, bis (4-pyridyl) ketone, etc. are mentioned.

These compounds are 0.1 to 10 molar equivalents of reactive groups per 1 molar equivalent of rubber active terminal lithium atom.
It is preferably used within a range of 0.2 to 3 molar equivalents. 0.
If it is less than 1 molar equivalent, the reactivity to carbon black is insufficient and the reinforcing property is small. On the other hand, if it exceeds 10 molar equivalent, the improvement effect reaches saturation and it is economically disadvantageous, which is not preferable.

The coupling reaction between the terminally active lithium and these compounds is carried out in the range of 0 ° C. to 150 ° C., and may be carried out under isothermal conditions or elevated temperature conditions.

The lithium amide initiator is prepared by reacting the organolithium compound with an amine compound or imine compound which is a secondary amine. Examples of amine compounds are dimethylamine, diethylamine, dipropylamine, di-n-butylamine, diisobutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, diallylamine, dicyclohexylamine, butylisopropylamine, dibenzylamine. , Methylbenzylamine, methylhexylamine,
Examples thereof include ethylhexylamine. Examples of the imine compound include trimethyleneimine, pyrrolidine, piperidine, 2-methylpiperidine, 3-methylpiperidine, 4-methylpiperidine, 3,5-dimethylpiperidine, 2-ethylpiperidine, hexamethyleneimine, heptamethyleneimine, morpholine, Examples thereof include N-methylpiperazine, N-ethylpiperazine, N-methylimidazolidine, N-ethylimidazolidine, oxazine, pyrroline, pyrrole and azepine.

The amount of the secondary amine is 0.01 to 20 molar equivalents, preferably 0.1 to 5.0 molar equivalents, and more preferably 0.2 to 1 molar equivalent of the organic lithium compound. It is 1.5 molar equivalents. When the amount of secondary amine increases, a phenomenon that increases hysteresis loss of rubber is observed. If this amount is less than 0.01 molar equivalent, the efficiency of introducing a tertiary amine at the polymer terminal decreases, and if it exceeds 20 molar equivalents, the amount of amine-containing oligomer that does not contribute to the improvement of physical properties increases, which is preferable. Absent.

The rubbers having a tin-containing group or a nitrogen-containing group at one end of the conjugated diene rubber or at one end of the conjugated diene / vinyl aromatic hydrocarbon copolymer rubber have been exemplified above. On the other hand, since the tin-containing initiator or the lithium amide initiator polymerizes the monomer in a living manner, the obtained rubber terminal becomes active lithium, and thus it is possible to react with the tin-containing compound or the nitrogen-containing compound described above. A rubber having tin-containing groups or nitrogen-containing groups at both ends of is obtained. Therefore, it is possible to obtain a rubber in which desired tin-containing groups or nitrogen-containing groups are arbitrarily introduced into one end and both ends of the rubber.

In the rubber composition of the present invention, the carbon black specified by the X characteristic and the Y characteristic interacts with the conjugated diene-based synthetic rubber to improve the low hysteresis loss property, and for the reinforcing effect by this interaction. It is considered that the wet skid property is improved. Further, when a conjugated diene rubber or a conjugated diene / vinyl aromatic hydrocarbon copolymer rubber having a modifying group such as a tin-containing group or a nitrogen-containing group at the terminal is used as the conjugated diene-based synthetic rubber, the effect of the rubber composition of the present invention Will increase even more. It is considered that this is because the modifying group of the rubber and the specified functional group on the surface of the carbon black show an extremely large interaction.

The rubber composition of the present invention contains the compounding agents usually used in the rubber industry, such as other reinforcing fillers, vulcanizing agents, stearic acid, zinc oxide, vulcanization accelerators, antiaging agents, A softening agent and the like can be appropriately added.

The rubber composition of the present invention is preferably used as a tread rubber for tires, a side rubber, especially a tread rubber, but also for other rubber products required to have low hysteresis loss, such as belts and shock absorbers. used.

[0054]

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.

Various measurements are as follows. · N in compliance with the measurement ASTM D3037 of ₂ SA (nitrogen adsorption specific surface area), the nitrogen specific surface area of the carbon black per 1g than adsorption amount of (N ^₂₎ (m ₂₎
I asked. -> C = O Measurement of functional group concentration 1) Preparation of oxime-formed carbon black Two Erlenmeyer flasks containing about 1.5 g of carbon black were prepared, and one flask was charged with 20 g of pyridine and 1 g of hydroxylamine hydrochloride. The melted solution is added with 20 ml of pyridine in the other flask. A condenser tube with a ball is attached to the upper part of the Erlenmeyer flask, and a calcium chloride tube and a deoxidizer are connected to the condenser tube. The whole apparatus is replaced by flowing nitrogen gas to create a nitrogen atmosphere.

The flask is placed in an oil bath maintained at 100 ° C. and reacted at this temperature for 16 hours. After completion of the reaction, 50 ml of 3N hydrochloric acid is added while cooling the reaction product to neutralize excess hydroxylamine. The content is suction filtered to separate the oxime carbon black, about 300 ml
Wash with distilled water. This is No. Transfer to 5B filter paper,
Wash with an additional 300 ml of distilled water.

1 after washing the oxime-carried carbon black
Put it in a drier kept at 05 ° C and dry it to a constant weight to prepare an oxime carbon black (the same operation is performed with a blank.) 2) Quantitation of nitrogen amount Preparation of sample for oxime carbon black About 0.2 g of the control carbon black is precisely weighed and placed in a semi-micro Kjeldahl decomposition bottle. Calcium sulfate 2.5 for each
g, 0.02 g of mercuric oxide, and finally 4 m of concentrated sulfuric acid
Add l.

The decomposition bottle is attached to a semi-micro Kjeldahl decomposition device, and tap water is poured into an exhaust gas suction aspirator to heat it. The intensity of the flame is weakened at first so that the contents of the decomposition bottle do not boil, and gradually increases as the white smoke in the decomposition bottle decreases, and the heat is increased to the extent of boiling. After the contents of the decomposition bottle become completely transparent, ignite for another hour. Turn off the heat and allow to cool to room temperature, remove the bottle from the decomposition apparatus and add about 10 ml of distilled water little by little. Then, the contents are put into a sample flask of a semi-micro Kjeldahl nitrogen distillation apparatus. Quantification of nitrogen amount A sample flask is attached to a distillation apparatus, and a beaker containing 5 ml of a 2% boric acid solution is connected to the outlet of a condenser tube with a bulb of the distillation apparatus. From the alkali inlet of the distillation apparatus, sodium hydroxide / sodium thiosulfate (50% / 5%) solution 2
Inject 5 ml, close the inlet and the vapor port, and perform distillation for 9 minutes.

1% of a 2% boric acid solution in which ammonia was dissolved
Titrate with 100N hydrochloric acid. Using an ammonium sulfate solution with a known amount of nitrogen, perform the above-mentioned operation to prepare a calibration curve, determine the milliequivalent of nitrogen from the titration amount of the sample and the calibration curve, and calculate the milliequivalent of> C = O functional group per 1 g of carbon black. Calculate (meq / g).

[0060]

(Equation 9)

-Measurement of -OH functional group concentration 1) Preparation of acetylated carbon black 20 ml of pyridine and 10 ml of acetic anhydride were placed in an Erlenmeyer flask containing about 2 g of carbon black, and a calcium chloride tube was placed above the condenser tube with a ball. Connect and connect a deoxidizer to this tube. The apparatus is replaced by flowing nitrogen gas to create a nitrogen atmosphere.

The flask is placed in an oil bath maintained at 120 ° C. and reacted at this temperature for 15 hours. After completion of the reaction, 100 ml of distilled water is added while cooling the reaction product to decompose excess acetic anhydride, and then acetylated carbon black is separated by suction filtration and washed with about 300 ml of distilled water.

1% of acetylated carbon black after washing
An acetylated carbon black is prepared by placing it in a dryer kept at 05 ° C. and drying it until a constant weight is obtained. 2) Determination of acetic acid About 1 g of acetylated carbon black is precisely weighed and placed in a beaker, and 20 ml of warm distilled water is added to 2 barium hydroxide.
g is added to the solution. The container is placed in a 100 ° C. water bath and hydrolysis is carried out for 5 hours. The contents are allowed to cool and suction filtered using a membrane filter. The beaker and the filter were washed with a small amount of distilled water, and the combined filtrate and washing solution was allowed to flow down a column of cation exchange resin Amberlite IR120 (manufactured by Organo Co.) activated with hydrochloric acid to release acetic acid. , Wash the column when no acetic acid is detected.

The effluent is titrated with a 1 / 500N sodium hydroxide solution using a mixed indicator of methyl red and bromocresol green.

Prior to this titration, a calibration curve was prepared in advance using a 1 / 500N acetic acid standard solution, and the amount of acetic acid was determined from this titration value using this calibration curve.

The milliequivalent (meq / g) of -OH functional group per 1 g of carbon black is calculated by the following formula.

[0067]

(Equation 10)

Measurement of Hysteresis Loss The internal loss (tan δ) was measured using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under the conditions of 1% tensile dynamic strain, 50 Hz frequency and 60 ° C. The test piece was a slab sheet with a thickness of about 2 mm and a width of 5 mm.
The initial load was 160 g with the distance between the samples being 2 cm. The value of tan δ is represented by an index with Comparative Example 1 being 100, and the smaller the value, the smaller the hysteresis loss property, which is preferable. -Measurement of wet skid property To evaluate wet skid property, a skid tester manufactured by Stanley London, England was used to measure slip resistance at room temperature on a concrete road surface whose surface was wet with water. The value is represented by an index with Comparative Example 1 being 100, and the larger the value, the better. -Measurement of rolling resistance performance The rubber composition was applied to a tread of a passenger car tire of 195 / 65R15 size, an internal pressure of 2.0 kg, and a load of 440.
A tire with 6 kg of rim and 6 JJ is brought into contact with a drum having an outer diameter of 1.7 m to rotate the drum, and a speed of 120 km / h.
After ascending, the drum was coasted, and the value was calculated from the moment of inertia when the speed was 80 km / hour. The numerical value is represented by an index with Comparative Example 1 being 100, and the larger the value, the more preferable.

[0069]

[Equation 11]

-Measurement of wet skid performance of tires The tires were mounted on a test trailer according to the method determined by running performance on a wet road surface, according to the UTQGS (tire quality grade standard) of the United States, and on a wet asphalt dense particle size road surface. And the frictional resistance when the rotation of the tire was locked was measured. The numerical value is represented by an index with Comparative Example 1 being 100,
The big method is good. Carbon black used in Comparative Examples and Examples 1) Carbon black used in Comparative Examples Carbon black A (control), B, C, D, E
Both F and F are normal furnace blacks, and ASTM codes N330, N660, N550 and N3, respectively.
39, N220 and N110. 2) Carbon black used in the examples Carbon black G is carbon black A which is oxidized at room temperature for 3 hours in an ozone atmosphere.

Carbon black H is carbon black G
Was heat-treated under nitrogen at 450 ° C. for 1 hour.

Carbon black I is produced by a gas furnace method using LPG as a raw material.

Carbon black J is a channel type carbon black of CK-3 (manufactured by Degussa, trade name).

Carbon black K is carbon black J
Is oxidized at room temperature for 3 hours in an ozone atmosphere.

Carbon black L is carbon black K
Was heat-treated under nitrogen at 450 ° C. for 1 hour.

Carbon black M is Special B
This is a channel-type carbon black of rack 4A (trade name, manufactured by Degussa), which is oxidized. -Rubber used in Comparative Examples and Examples 1) SBR is # 1500 manufactured by Japan Synthetic Rubber Co., Ltd. 2) Modified SBR1 is styrene 1kg, butadiene 4kg
In a cyclohexane solvent, n-butyllithium 48
Using mmol and 250 g of tetrahydrofuran, 1
The butadiene-styrene random copolymer obtained by copolymerization at 0 ° C for 30 minutes was coupled with 12 mmol of tin tetrachloride. The styrene content of the copolymer before coupling was 20%, the vinyl content of the butadiene part was 60%, and the weight average molecular weight was 2.1 × 10 ^5.
Met. 3) Modified SBR2 is a butadiene-styrene random copolymer obtained in the same manner as modified SBR1 modified with 12 mmol of diethylaminobenzophenone. The molecular structure of the copolymer before modification is the same as that of modified SBR1.

Example 1 A rubber composition was prepared using carbon black G, natural rubber and modified SBR1 according to the compounding recipes in Tables 2 and 3, and vulcanized at 150 ° C. for 40 minutes. . The results of measuring the characteristics of carbon black G are shown in Table 1. Hysteresis loss property of vulcanizate (tan δ)
Table 3 shows the evaluation results of physical properties such as wet skid property. In addition, the rubber composition used in the tread was 195 /
Table 4 shows the results of evaluation of rolling resistance performance, wet skid performance and the like of a 65R15 size passenger car tire.

[Examples 2 to 10, Comparative Examples 1 to 7] In the same manner as in Example 1, various carbon blacks and various rubbers were used to obtain rubber compositions and tires. The results of measuring the properties of each carbon black are shown in Table 1, the results of measuring the physical properties of each vulcanized product are shown in Table 3, and the results of evaluating the performance of each tire are shown in Table 4.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3]

[0082]

[Table 4]

As shown in Table 3, the rubber composition of the present invention is extremely excellent in low hysteresis loss, and at the same time, has high wet skid property. Further, as shown in Table 4, it is clear that the pneumatic tire using the rubber composition of the present invention has significantly improved low rolling resistance performance and excellent wet skid performance.

As can be seen from the comparative examples, the rubber composition using carbon black in which the two properties of carbon black do not satisfy the claims at the same time is inferior in either low hysteresis loss property or wet skid property,
That is, they exhibit antinomy properties, and similarly, a tire using this rubber composition cannot similarly satisfy low rolling resistance performance and wet skid performance at the same time. As shown in Example 8 (using normal SBR) and other examples (using modified SBR), in the present invention, the rubber-rubber composition using modified SBR as a rubber and its tire have a greater effect. I understand.

[0085]

Since the rubber composition of the present invention has the above constitution, the low hysteresis loss property is remarkably improved, and at the same time, the wet skid property is at a high level, and the pneumatic tire using this rubber composition is also improved. Has significantly improved low rolling resistance performance and has a high level of wet skid performance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C09C 1/48 PBE C09C 1/48 PBE 1/56 PBH 1/56 PBH

Claims (12)

[Claims] 1. It has both properties represented by the following formula (I) and formula (II) with respect to 100 parts by weight of at least one rubber selected from the group consisting of conjugated diene-based synthetic rubber and natural rubber. A rubber composition comprising 30 to 120 parts by weight of carbon black. Formula (I) Formula (II) [Equation 2] (Where [> C = O functional group concentration] is the functional group concentration (meq /
g), and N ₂ SA is a nitrogen adsorption specific surface area (m ² / m
g), and [-OH functional group concentration] represents the functional group concentration (meq / g) that causes an acetylation reaction with acetic anhydride. ) 2. The rubber composition according to claim 1, wherein the conjugated diene-based synthetic rubber is polybutadiene rubber and / or styrene-butadiene rubber. 3. The rubber composition according to claim 1, wherein the conjugated diene-based synthetic rubber is a rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group. 4. A rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group in a polybutadiene rubber and / or a styrene-butadiene rubber, wherein the conjugated diene-based synthetic rubber is a rubber. The rubber composition according to 1. 5. The carbon black is a carbon black obtained by subjecting at least one selected from the group consisting of furnace black and channel type carbon black to an oxidizing treatment by an oxidizing means. The rubber composition according to claim 1. 6. The carbon black, wherein at least one selected from the group consisting of furnace black and channel type carbon black is subjected to oxidation treatment by an oxidizing means, and further subjected to heat treatment at a temperature of 100 to 900 ° C. The rubber composition according to claim 1, which is the obtained carbon black. 7. A pneumatic tire having a tread portion, a sidewall portion and a bead portion, wherein the tread portion has 100 parts by weight of at least one rubber selected from the group consisting of conjugated diene synthetic rubber and natural rubber. On the other hand, a pneumatic tire characterized by using a rubber composition comprising 30 to 120 parts by weight of carbon black having both properties represented by the following formula (I) and formula (II). . Formula (I) Formula (II) [Equation 4] (Where [> C = O functional group concentration] is the functional group concentration (meq /
g), and N ₂ SA is a nitrogen adsorption specific surface area (m ² / m
g), and [-OH functional group concentration] represents the functional group concentration (meq / g) that causes an acetylation reaction with acetic anhydride. ) 8. The pneumatic tire according to claim 7, wherein the conjugated diene-based synthetic rubber is polybutadiene rubber and / or styrene-butadiene rubber. 9. The pneumatic tire according to claim 7, wherein the conjugated diene-based synthetic rubber is a rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group. 10. A rubber having a functional group selected from the group consisting of a tin-containing group and a nitrogen-containing group in a polybutadiene rubber and / or a styrene-butadiene rubber, wherein the conjugated diene-based synthetic rubber is a rubber. The pneumatic tire according to 7. 11. The carbon black is a carbon black obtained by subjecting at least one selected from the group consisting of furnace black and channel type carbon black to an oxidizing treatment by an oxidizing means. The pneumatic tire according to claim 7. 12. The carbon black, wherein at least one selected from the group consisting of furnace black and channel-type carbon black is subjected to oxidation treatment by an oxidizing means, and further subjected to heat treatment at a temperature of 100 to 900 ° C. The pneumatic tire according to claim 7, which is the obtained carbon black.