JP2008239936A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which is used for a tread or the like which is excellent in travel motion stability in a wetting road surface (wet skid capability) and low rolling resistance property (low pyrogenicity) and to provide a pneumatic tire using the rubber composition. <P>SOLUTION: The rubber composition of this invention comprises, based on a rubber component (A) of 100 pts.mass, an aromatic vinyl compound-conjugated diene compound copolymer (B) in the range of 2-60 pts.mass in which the mass average molecular weight (in terms of polystyrene, measured by gel permeation chromatography) is in the range of 5,000-500,000; and an inorganic compound powder (C) in the range of 3-30 pts.mass having a grain size of 10 μm or less, and comprising at least one or more sorts of a metal oxide expressed by general formula M-xSiO<SB>2</SB>-yH<SB>2</SB>O (1), or a metal hydroxide, and hydrates thereof, wherein in the formula (1), M is either of aluminum, magnesium, titanium, and calcium, x and y are an integer of 0-10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition and a pneumatic tire. In detail, it is related with the pneumatic tire which improved the physical property of the rubber composition used for a tread rubber part, and improved tire performance.

  In general, as shown in FIG. 1, a pneumatic tire includes a pair of bead portions 3, a pair of sidewall portions 4, and a tread portion 1, a carcass layer 6 that extends in a toroid shape and is locked to the bead core 2, The belt layer 7 is located on the outer periphery of the crown portion, and the tread rubber layer 8 is located on the outer side in the tire radial direction. In a pneumatic tire, the characteristics of the rubber composition of the tread portion 1 are extremely important for reducing rolling resistance (or low heat generation) of the tire and for running safety on a wet road surface. .

In recent years, automobile tires are required to improve tire performance, for example, advanced low rolling resistance characteristics and driving safety (wet skid performance) on wet roads due to demands for carbon dioxide reduction and driving safety. Is in a situation where In this connection, improvement of tread rubber is desired.
Conventionally, in a rubber composition for a tire tread, silica is blended in a filler in order to achieve improvement in wet skid performance and low heat build-up (see, for example, Patent Documents 1 to 3). However, only by silica modification, low rolling resistance and wet skid performance cannot be sufficiently achieved.
JP 2006-225600 A JP 2004-355773 A JP 2001-89598 A

  In view of the above problems, the present invention is to provide a rubber composition for a tire tread in which improvement in wet skid performance and improvement in low heat generation are both highly compatible, and a pneumatic tire using the rubber composition.

As a result of intensive studies to solve the above problems, the present inventor blended a rubber component (A) with a low molecular (B) aromatic vinyl compound-diene compound copolymer, and further added an auxiliary filler. By including a specific inorganic compound powder (C) having a relatively small particle size as a tread rubber composition excellent in running stability on wet road surfaces and low heat build-up (low rolling resistance) And the present invention has been completed.
The (B) aromatic vinyl compound-diene compound copolymer is modified with a tin-containing compound or a silicon-containing compound to introduce tin and silicon functional groups, and (B) an aromatic vinyl compound- The present inventors have found that by introducing a nitrogen-containing functional group into the diene compound copolymer, the performance can be further improved, and the present invention has been achieved.
That is, the present invention is characterized by the following configuration or structure.

(1) The rubber component (A) has a mass average molecular weight (polystyrene conversion measured by gel permeation chromatography) in the range of 5,000 to 500,000 and contains a functional group with respect to 100 parts by mass of the rubber component (A). The metal oxide or metal hydroxide represented by the following general formula (1) and water thereof containing the aromatic vinyl compound-conjugated diene compound copolymer (B) in the range of 2 to 60 parts by mass. A rubber composition comprising an inorganic compound powder (C) having an average particle diameter of 10 μm or less and comprising 3 to 30 parts by mass of at least one kind of a Japanese product.
M · xSiO ₂ · yH ₂ O (1) [wherein, in formula (1), M is any one of aluminum, magnesium, titanium, and calcium, and x and y are 0-10. It is an integer. ]

(2) The copolymer (B) is composed of an aromatic vinyl compound of 5 to 80% by mass, and the vinyl bond content of the conjugated diene compound portion of the copolymer (B) is 10 to 80% by mass. The rubber composition as described in (1) above, wherein
(3) The aromatic vinyl compound-conjugated diene compound copolymer (B) contains at least one modified functional group selected from a tin-containing functional group, a silicon-containing functional group, and a nitrogen-containing functional group. The rubber composition as described in (1) above, which is a copolymer.
(4) The nitrogen-containing functional group is at least one selected from a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, and pyridyl group. Rubber composition.
(5) The rubber composition according to the above (1), wherein the rubber component (A) contains 50% by mass or more of styrene-butadiene copolymer rubber.
(6) The rubber composition according to (1), wherein the aromatic vinyl compound in the aromatic vinyl compound-conjugated diene compound copolymer (B) is styrene.
(7) The rubber composition according to the above (1), wherein the conjugated diene compound in the aromatic vinyl compound-conjugated diene compound copolymer (B) is 1,3-butadiene.
(8) The aromatic vinyl compound-conjugated diene compound copolymer (B) has a mass average molecular weight (polystyrene conversion measured by gel permeation chromatography) in the range of 20,000 to 400,000 (1). The rubber composition as described.
(9) The aromatic vinyl compound-conjugated diene compound polymer (B) has a mass average molecular weight (in terms of polystyrene measured by gel permeation chromatography) before introducing a functional group in the range of 5,000 to 200,000. The rubber composition as described in (1) above.
(10) The rubber composition according to claim 1, wherein the inorganic compound powder (C) represented by the general formula (1) is an inorganic compound powder represented by the following general formula (2).
Al ₂ O ₃ mSi ₂ .nH ₂ O (2) [wherein, m is an integer of 1 to 4 and n is an integer of 0 to 4 in the formula (2). ]
(11) The rubber composition according to (10), wherein the inorganic compound powder (C) represented by the general formula (2) is an aluminum hydroxide powder.
(12) A pneumatic tire using the rubber composition according to any one of (1) to (11) as at least a ground contact portion of a tire tread portion.

  According to the present invention, by blending the aromatic vinyl compound-conjugated diene compound copolymer (B) having a predetermined molecular structure and including the specific inorganic compound powder (C), hysteresis in a high temperature range is achieved. The loss of loss can be reduced, the increase in hysteresis loss in the low to medium temperature range can be suppressed, and a rubber composition for tire tread can be obtained by containing a specific inorganic compound powder. And in the tire which uses such a rubber composition as a tread, it can be set as the pneumatic tire which made wet skid performance and low heat generation highly compatible.

Embodiments of the present invention will be described below.
The rubber composition according to the present invention is an aromatic vinyl having a mass average molecular weight (in terms of polystyrene measured by gel permeation chromatography) in the range of 5,000 to 500,000 with respect to 100 parts by mass of the rubber component (A). The compound-conjugated diene compound copolymer (B) is contained in the range of 2 to 60 parts by mass, and the metal oxide or metal hydroxide represented by the following general formula (1) and hydrates thereof The inorganic compound powder (C) comprising at least one kind and having an average particle diameter of 10 μm or less is contained in the range of 3 to 30 parts by mass.
M · xSiO ₂ · yH ₂ O (1)
Here, in Formula (1), M is any of aluminum, magnesium, titanium, and calcium, and x and y are integers of 0 to 10. The rubber composition shown below is arranged on the base rubber part.

<Rubber component (A)>
The rubber component (A) comprises at least one of natural rubber (NR) and synthetic diene rubber, and any of unmodified rubber and modified rubber may be used as the rubber component. Here, as the synthetic diene rubber, those synthesized by emulsion polymerization or solution polymerization are preferable.
Specific examples of the synthetic diene rubber include polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber ( CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like. Particularly preferred are natural rubber, polyisoprene rubber (IR), polybutadiene rubber (BR), halogenated (Br) butyl rubber and the like. Particularly preferred rubber components are natural rubber, polybutadiene rubber (BR), polyisoprene rubber (IR), and styrene-butadiene copolymer rubber (SBR).
The said rubber component may be used individually by 1 type, and may blend and use 2 or more types. In addition, from the viewpoint of wear resistance and heat resistance of the rubber composition, the rubber component preferably has a glass transition temperature (Tg) of −60 ° C. or higher.

In the present invention, the rubber component (A) preferably contains 50% by mass or more of styrene-butadiene copolymer rubber (SBR). When the rubber component (A) contains 50% by mass or more of styrene-butadiene copolymer rubber, it is preferable in that the improvement effect by the combination of the copolymer (B) described later becomes clear.
The rubber component (A) containing a styrene-butadiene copolymer rubber (SBR) component can ensure compatibility within the predetermined range, and stably provide an improvement in storage elastic modulus and tan ∂. More preferably, the copolymer rubber is an emulsion polymerized styrene-butadiene copolymer and / or a solution polymerized styrene-butadiene copolymer.

<Aromatic vinyl compound-conjugated diene compound copolymer (B)>
The aromatic vinyl compound-conjugated diene compound copolymer (B) has a weight average molecular weight (polystyrene conversion measured by gel permeation chromatography) in the range of 5,000 to 500,000 and contains a specific functional group. It becomes.
A copolymer (B) is contained in 2-70 mass parts with respect to 100 mass parts of rubber components (A). Preferably, it contains in the range of 5-50 mass parts, More preferably, it contains in the range of 10-40 mass parts. When the blending amount of the aromatic vinyl compound-conjugated diene compound copolymer is less than 2 parts by mass, the effect of improving the braking performance is insufficient as a rubber composition for a tread. It deteriorates and the destructive properties of the vulcanized rubber deteriorate.

  The aromatic vinyl compound-conjugated diene compound copolymer has a mass average molecular weight (polystyrene conversion by gel permeation chromatography) obtained by copolymerizing an aromatic vinyl compound as a monomer and a conjugated diene compound. Copolymer in ˜500,000. Preferably, it is 20,000-400,000, More preferably, it is 50,000-400,000. Higher molecular weight materials are superior in storage elastic modulus and loss coefficient, but workability is lowered at 500,000 or more. The molecular weight distribution is preferably narrow. If it is wide, the loss factor tends to be inferior.

Moreover, it is preferable that a copolymer consists of 5-80 mass% aromatic vinyl compounds. Moreover, it is preferable that the vinyl bond amount of the part of a conjugated diene compound is 10-80 mass%.
A copolymer comprising a conjugated diene compound having a vinyl content ratio of less than 5% by mass or greater than 80% by mass and less than 10% or greater than 80% deteriorates workability. Further, durability and rolling resistance in the tire are not sufficiently improved. In addition, the vinyl amount prescribed | regulated here shows the vinyl amount in the structural unit derived from a diene compound, and shows the ratio of all the vinyl amounts represented by a cis bond and a trans bond.

Examples of the aromatic vinyl compound include styrene, p-methylstyrene, m-methylstyrene, p-tert-butylstyrene, α-methylstyrene, chloromethylstyrene, vinyltoluene and the like. Preferable examples include styrene, p-methylstyrene, and α-methylstyrene. In particular, styrene is preferable.
As the diene compound, butadiene, isoprene, pentadiene, 2,3-dimethylbutadiene or the like is used, and 1,3-butadiene is particularly preferable.
The copolymer can be obtained by various production methods as long as a predetermined molecular structure is given. As the copolymer, various liquid or low molecular weight polymers or rubbers can be applied. Preferably, the copolymer is suitably produced by solution polymerization of styrene and butadiene. Particularly preferably, the copolymer is a solution polymerized styrene-butadiene copolymer rubber.
An example of an industrial method is a method in which a predetermined monomer is copolymerized in a hydrocarbon solvent using an organolithium compound as an initiator. For example, the copolymer can be prepared in a tank or tower reactor using a small amount of 1,2-butadiene in a hydrocarbon solvent using an organolithium compound initiator in the presence of ether or tertiary amine. It can be obtained by copolymerizing a diene compound such as 1,3-butadiene and an aromatic vinyl compound.

In the present invention, the aromatic vinyl compound-conjugated diene compound copolymer is modified, and the copolymer has at least one functional group. And the functional group contained in the copolymer can be any one of tin-containing functional group, silicon-containing functional group, nitrogen-containing functional group, or two or more of these, improving heat generation durability. This is preferable.
The aromatic vinyl compound-conjugated diene compound copolymer having such a functional group is modified with a tin-containing compound, a silicon-containing compound, or a nitrogen-containing compound.
The aromatic vinyl compound-conjugated diene compound compound copolymer having a functional group preferably has a polystyrene-reduced mass average molecular weight of 5,000 to 200,000 measured by gel permeation chromatography before introducing the functional group. In particular, it is preferably 20,000 to 150,000, and more preferably 50,000 to 150,000. In this case, the storage average modulus (G ′) of the rubber composition is improved by setting the mass average molecular weight after introduction of the functional group to a range of 5,000 to 500,000, particularly preferably in the range of 50,000 to 400,000. It is easy to reduce loss tangent (tan ∂) and secure workability.

  The aromatic vinyl compound-conjugated jun compound copolymer having the above functional group is obtained by copolymerizing (1) a monomeric aromatic vinyl compound and a conjugated diene compound using a polymerization initiator, And a method of modifying the polymerization active site with various modifiers, and (2) a monomeric aromatic vinyl compound and a conjugated diene compound. It can be obtained by a method of copolymerization using a polymerization initiator having a functional group.

Here, the aromatic vinyl compound-conjugated diene compound copolymer having a polymerization active site may be produced by anionic polymerization or may be produced by coordination polymerization.
When producing an aromatic vinyl compound-conjugated diene compound compound copolymer having a polymerization active site by anionic polymerization, an organic alkali metal compound is preferably used as a polymerization initiator, and a lithium compound is more preferably used.

In the rubber composition, the low molecular weight aromatic vinyl compound-conjugated diene compound compound copolymer having a nitrogen functional group includes a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, and biridyl group. Is preferably represented by the formula (I): (R ¹ ) ₂ N— [wherein R ^{1 s} are each independently an alkyl group, cycloalkyl group or aralkyl group having 1 to 12 carbon atoms]. Substituted amino group and formula (II): R ² = N— [where, = is ylene, R ² is an alkylene group having 3 to 16 methylene groups, substituted alkylene group, oxyalkylene A cyclic amino group represented by the formula: or a N-alkylamino-alkylene group]. These nitrogen-containing functional groups have a high filler dispersion effect in rubber compositions containing various fillers such as carbon black, silica, and aluminum hydroxide, and greatly improve the storage elastic modulus of rubber compositions of all kinds. Loss tangent (tan ∂) is greatly reduced.

Examples of lithium compounds include hydrocarbyl lithium and lithium amide compounds.
When hydrocarbyl lithium is used as the polymerization initiator, a copolymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained.
On the other hand, when a lithium amide compound is used as a polymerization initiator, a copolymer having a nitrogen-containing functional group at the polymerization start terminal and the other terminal being a polymerization active site is obtained, and the copolymer is a modifier. Even if not modified, it can be used as a copolymer in the present invention. In addition, the usage-amount of the organic alkali metal compound as a polymerization initiator has the preferable range of 2-20 mmol per 100g of monomers.

  Examples of the hydrocarbyl lithium include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl-phenyl. Examples include lithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and among these, ethyllithium, n-propyllithium, isopropyllithium, n Alkyllithium such as -butyllithium, sec-butyllithium, tert-octyllithium and n-decyllithium is preferable, and n-butyllithium is particularly preferable.

  On the other hand, the lithium amide compounds include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium Dihexylamide, lithium diheptylamide, lithium dioctylamide, lythym-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium methylbutyramide, lithium ethylbenzylamide, Lithium methyl phenethyl amide, etc., among which lithium hexamethylene imide, lithium pyrrolidide, lithium Umupiperijido, lithium heptamethylene imide, preferably lithium amide compound of the cyclic such as lithium dodecamethylene imide, lithium hexamethylene imide and lithium pyrrolidide are particularly preferable.

As the lithium amide compound, lithium represented by the formula: Li-AM [wherein AM is a substituted amino group represented by the above formula (I) or a cyclic amino group represented by the formula (II)] Low molecular weight in which at least one nitrogen-containing functional group selected from the group consisting of a substituted amino group represented by formula (I) and a cyclic amino group represented by formula (II) is introduced by using an amide compound An aromatic vinyl compound-conjugated diene compound compound copolymer (B) is obtained.
In the formula (I), R ¹ is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aralkyl group, specifically, a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, Preferable examples include 3-phenyl-1-propyl group and isobutyl group. R ^l may be the same or different.

In the formula (II), R ² is an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group. Here, the substituted alkylene group includes a 1- to 8-substituted alkylene group, and examples of the substituent include a chain or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a bicycloalkyl group, and an aryl group. Groups and aralkyl groups. R ² is preferably a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, or the like.

  The lithium amide compound may be preliminarily prepared from a secondary amine and a lithium compound and used for the polymerization reaction, but may be generated in a polymerization system. Here, examples of the secondary amine include dimethylamine, diethylamine, dibutylamine, dioctylamine, dicyclohexylamine, diisobutylamine and the like, azacycloheptane (ie, hexamethyleneimine), 2- (2-ethylhexyl) pyrrolidine, 3- (2-propyl) pyrrolidine, 3,5-bis (2-ethylhexyl) piperidine, 4-phenylpiperidine, 7-decyl-1-azacyclotridecane, 3,3-dimethyl-1-azacyclotetradecane, 4-dodecyl-1-azacyclooctane, 4- (2-phenylbutyl) -1-azacyclooctane, 3-ethyl-5-cyclohexyl-1-azacycloheptane, 4-hexyl-1-azacycloheptane, 9-isoamyl-1-azacycloheptadecane, 2-methyl-1-aza Chloheptade-9-ene, 3-isoptyruteazacyclododecane, 2-methyl-7-tert-butyl-1-azacyclododecane, 5-nonyl-toazacyclododecane, 8- (4′-methylphenyl)- 5-pentyl-3-azabicyclo [5,4.0] undecane, 1-butyl-6-azabicyclo [3.2.1] octane, 8-ethyl-3-azabicyclo [3.2.1] octane, Propyl-3-azabicyclo [3.2.2] nonane, 3- (t-butyl) -7-azabicyclo [4.3.0] nonane, 1,5,5-trimethyl-3-azabicyclo [4.4. 0] cyclic amines such as decane. On the other hand, as the lithium compound, the above hydrocarbyl lithium can be used.

  The method for producing an aromatic vinyl compound-conjugated Jun compound copolymer by anionic polymerization using the above organic alkali metal compound or the like as a polymerization initiator is not particularly limited. For example, in a hydrocarbon solvent inert to the polymerization reaction. Thus, a copolymer can be produced by polymerizing a mixture of a conjugated diene compound and an aromatic vinyl compound. Here, as the hydrocarbon solvent inert to the polymerization reaction, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, tobutene, isobutene, trans-2-butene, cis-2- Examples include butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. These may be used alone or in combination of two or more.

  The anionic polymerization may be performed in the presence of a randomizer. The randomizer can control the microstructure of the conjugated diene compound portion of the copolymer. More specifically, the randomizer can control the vinyl bond amount of the conjugated diene compound portion of the copolymer, The conjugated Jun compound unit and the aromatic vinyl compound unit are randomized. Examples of the randomizer include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, 1 , 2-dipiperidinoethane, potassium t-amylate, potassium t-butoxide, sodium t-amylate and the like. The amount of these randomizers used is preferably in the range of 0.01 to 100 molar equivalents per mole of polymerization initiator.

The anionic polymerization is preferably carried out by solution polymerization, and the concentration of the monomer in the polymerization reaction solution is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass. In addition, the content rate of the aromatic vinyl compound in the mixture of a conjugated diene compound and an aromatic vinyl compound is the range of 5-80 mass% as above-mentioned. Therefore, it can be appropriately selected according to the amount of the aromatic vinyl compound of the target copolymer. Further, the polymerization mode is not particularly limited, and may be batch type or continuous type.
The polymerization temperature of the anionic polymerization is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 130 ° C. The polymerization can be carried out under a generated pressure, but it is usually preferred to carry out the polymerization under a pressure sufficient to keep the monomer used in a substantially liquid phase. Here, when the polymerization reaction is carried out under a pressure higher than the generated pressure, it is preferable to pressurize the reaction system with an inert gas. Moreover, it is preferable to use what removed reaction-inhibiting substances, such as water, oxygen, a carbon dioxide, and a protic compound, as raw materials, such as a monomer used for superposition | polymerization, a polymerization initiator, and a solvent.

On the other hand, when producing an aromatic vinyl compound-conjugated diene compound compound copolymer having a polymerization active site by coordination polymerization, a rare earth metal compound is preferably used as the polymerization initiator, and the following component (a), ( More preferably, the component (b) and the component (c) are used in combination.
The component (a) used for the coordination polymerization is selected from a rare earth metal compound, a complex compound of a rare earth metal compound and a Lewis base, and the like. Here, examples of rare earth metal compounds include rare earth element carboxylates, alkoxides, β-diketone complexes, phosphates and phosphites, and Lewis bases include acetylacetone, tetrahydrofuran, pyridine, N, N. -Dimethylformamide, thiophene, diphenyl ether, triethylamine, an organic phosphorus compound, monovalent or divalent alcohol, etc. are mentioned. As the rare earth element of the rare earth metal compound, lanthanum, neodymium, praseodymium, samarium and gadolinium are preferable, and among these, neodymium is particularly preferable. Specific examples of the component (a) include neodymium tri-2-ethylhexanoate, a complex compound thereof with acetylacetone, neodymium trineodecanoate, a complex compound thereof with acetylacetone, neodymium tri-n-butoxide, and the like. It is done. These (a) components may be used individually by 1 type, or 2 or more types may be mixed and used for them.

The component (b) used for the coordination polymerization is selected from organoaluminum compounds. As the organoaluminum compound, specifically, a trihydrocarbyl aluminum compound represented by the formula: R ₃ Al, a hydrocarbyl aluminum hydride represented by the formula: R ₂ AIH or RAIH ₂ (wherein R is independently And a hydrocarbylaluminoxane compound having a hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum hydride, alkylaluminum dihydride, alkylaluminoxane, and the like. These compounds may be used alone or in combination of two or more. In addition, as (b) component, it is preferable to use aluminoxane and another organoaluminum compound together.

  The component (c) used in the coordination polymerization is a compound having a hydrolyzable halogen or a complex compound thereof with a Lewis base; an organic halide having a tertiary alkyl halide, benzyl halide or allyl halide; a non-coordinating anion And an ionic compound comprising a counter cation. Specific examples of the component (c) include alkylaluminum dichloride, dialkylaluminum chloride, silicon tetrachloride, tin tetrachloride, complexes of zinc chloride with Lewis bases such as alcohol, magnesium chloride and Lewis such as alcohol. Examples include complexes with bases, benzyl chloride, t-butyl chloride, benzyl bromide, t-butyl bromide, triphenylcarbonium tetrakis (pentafluorophenyl) borate and the like. These (c) components may be used individually by 1 type, or 2 or more types may be mixed and used for them.

In addition to the components (a), (b), and (c), the polymerization initiator is preliminarily used, if necessary, using the same conjugated diene compound and / or aromatic vinyl compound as the polymerization monomer. May be prepared. Further, part or all of the component (a) or the component (c) may be supported on an inert solid. Although the usage-amount of said each component can be set suitably, (a) component is 0.001-0.5 mol normally per 100g of monomers. The molar ratio (b) component / (a) component is preferably 5 to 1000, and (c) component / (a) component is preferably 0.5 to 10.
The polymerization temperature in the coordination polymerization is preferably in the range of −80 to 150 ° C., and more preferably in the range of −20 to 120 ° C. Moreover, as a solvent used for coordination polymerization, a hydrocarbon solvent inert to the reaction exemplified in the above-mentioned anionic polymerization can be used, and the concentration of the monomer in the reaction solution is the same as in the case of anionic polymerization. . Furthermore, the reaction pressure in coordination polymerization is the same as that in the case of anionic polymerization, and it is desirable that the raw material used for the reaction substantially removes reaction inhibitors such as water, oxygen, carbon dioxide, and protic compounds.

  In modifying the polymerization active site of the copolymer having a polymerization active site with a modifier, the modifier used is preferably a nitrogen-containing compound, a silicon-containing compound or a tin-containing compound. In this case, a nitrogen-containing functional group, a silicon-containing functional group, or a tin-containing functional group can be introduced by a modification reaction.

  The nitrogen-containing compound that can be used as the modifier preferably has a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, or biridyl group. Suitable nitrogen-containing compounds as the modifier include isocyanate compounds such as diphenylmethane diisocyanate, crude MDI, trimethylhexamethylene diisocyanate, tolylene diisocyanate, 4- (dimethylamino) benzophenone, 4- (diethylamino) benzophenone, 4-dimethylamino. Examples include benzylideneaniline, 4-dimethylaminobenzylidenebutylamine, dimethylimidazolidinone, N-methylpyrrolidone and the like.

Examples of the silicon-containing compound that can be used as the modifier include the following formula (III):
^{A-R 3 (R 4)} n -Si- (OR 5) 3-n ··· (III)
[Wherein A is (thio) epoxy, (thio) inocyanate, (thio) ketone, (thio) aldehyde, imine, amide, isocyanuric acid triester, (thio) carponic acid hydrocarbyl ester, (thio) carboxylic acid One having at least one functional group selected from metal salts, carboxylic anhydrides, carboxylic acid halides, dihydrocarbyl carbonates, cyclic tertiary amines, acyclic tertiary amines, nitriles, pyridines, sulfides and multisulfides. R ³ is a single bond or a divalent inert hydrocarbon group; R ⁴ and R ⁵ are each independently a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or 6 to 6 carbon atoms. 18 monovalent aromatic hydrocarbon group; n is an integer from 0 to 2; if OR ⁵ there is a plurality, the plurality of OR ⁵ may be the same as or different from each other; In addition, the molecule does not contain active protons and onium salts], and hydrocarbyloxysilane compounds and partial condensates thereof, and the following formula (IV):
R ⁶ _p —Si— (OR ⁷ ) _4-p (IV)
[Wherein, R ⁶ and R ⁷ are each independently a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms; It is ~ 2 integer; If oR ⁷ there are a plurality, a plurality of oR ⁷ each other may be the same or different; hydrocarbyloxy represented by not included active proton and onium salt are also in the molecule] Silane compounds and partial condensates thereof are also preferred.

In formula (III), among the functional groups in A, imine includes ketimine, aldimine and amidine, (thio) carboxylic acid ester includes unsaturated carboxylic acid ester such as acrylate and methacrylate, Tertiary amines include N, N-disubstituted aromatic amines such as N, N-disubstituted anilines, and cyclic tertiary amines can include (thio) ethers as part of the ring. Examples of the metal of the metal salt of (thio) carboxylic acid include alkali metals, alkaline earth metals, Al, Sn, Zn and the like.
The divalent inert hydrocarbon group in R ³ is preferably an alkylene group having 1 to 20 carbon atoms. The alkylene group may be linear, branched or cyclic, but is particularly preferably linear. Examples of the linear alkylene group include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and a dodecamethylene group.

Examples of R ⁴ and R ⁵ include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, and an aralkyl group having 7 to 18 carbon atoms. Here, the alkyl group and alkenyl group may be linear, branched, or cyclic, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, cyclopentyl, cyclohexyl, vinyl, propenyl, allyl, hexenyl, octenyl Group, cyclopentynyl group, cyclohexenyl group and the like. The aryl group may have a substituent such as a lower alkyl group on the aromatic ring, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Furthermore, the aralkyl group may have a substituent such as a lower alkyl group on the aromatic ring, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

In the formula (III), n is an integer of 0 to 2, but 0 is preferable, and it is necessary that this molecule does not have active protons and onium salts.
Examples of the hydrocarbyloxysilane compound represented by formula (III) include (thio) epoxy group-containing hydrocarbyloxysilane compounds such as 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, (2 -Glycidoxyethyl) methyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl) methyldimethoxysilane, 2- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl (methyl) dimethoxysilane and epoxies in these compounds Replace the group with a thioepoxy group Can be exemplified ones, among them, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyl triethoxysilane are particularly preferred.

  Further, as imine group-containing hydrocarbyloxysilane compounds, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N- (tomethylethylidene) -3- (triethoxysilyl) ) -1-propanamine, N-ethylidene-3- (triethoxysilyl) -1-propanamine, N- (tomethylpropylidene) -3- (triethoxysilyl) -1-propanamine, N- (4 -N, N-dimethylaminobenzylidene) -3- (triethoxysilyl) -1-propanamine, N- (cyclohexylidene) -3- (triethoxysilyl) -1-propanamine and their triethoxysilyl compounds Trimethoxysilyl compounds, methyldiethoxysilyl compounds, ethyldiethoxysilyl compounds, methyl A dimethoxysilyl compound, an ethyldimethoxysilyl compound, etc. can be mentioned, Among these, N- (1-methylpropylidene) -3- (triethoxysilyl) -1-propanamine and N- (1,3- Dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine is particularly preferred.

  Furthermore, imine (amidine) group-containing compounds include 1- [3- (triethoxysilyl) propyl] -4,5-dihydroimidazole, 1- [3- (trimethoxysilyl) propyl] -4,5-dihydro. Imidazole, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole, N- (3-isopropoxysilylpropyl) -4,5-dihydroimigzole, N- (3-methyldiethoxysilylpropyl) ) -4,5-dihydroimidazole and the like. Among these, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole is preferable.

  Furthermore, as the carboxylic acid ester group-containing compound, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltri Examples thereof include isopropoxysilane, and among these, 3-methacryloyloxypropyltrimethoxysilane is preferable.

  Examples of the isocyanate group-containing compound include 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, and 3-isocyanatopropyltriisopropoxysilane. Of these, 3-isocyanatopropyltriethoxysilane is preferred.

Furthermore, examples of the carboxylic acid anhydride-containing compound include 3-triethoxysilylpropyl succinic anhydride, 3-trimethoxysilylpropyl succinic anhydride, 3-methyldiethoxysilylpropyl succinic anhydride, and the like. Among these, 3-triethoxysilylpropyl succinic anhydride is preferable.
Examples of the cyclic tertiary amine group-containing hydrocarbyloxysilane compound include 3- (1-hexamethyleneimino) propyl (triethoxy) silane, 3- (1-hexamethyleneimino) propyl (trimethoxy) silane, and (1-hexamethylene). Imino) methyl (trimethoxy) silane, (1-hexamethyleneimino) methyl (triethoxy) silane, 2- (1-hexamethyleneimino) ethyl (triethoxy) silane, 2- (1-hexamethyleneimino) ethyl (trimethoxy) silane 3- (1-pyrrolidinyl) propyl (triethoxy) silane, 3- (1-pyrrolidinyl) propyl (trimethoxy) silane, 3- (1-heptamethyleneimino) propyl (triethoxy) silane, 3- (1-dodecamethylene) Imino) propyl (triethoxy Silane, 3- (1-hexamethyleneimino) propyl (diethoxy) methylsilane, 3- (1-hexamethyleneimino) propyl (diethoxy) ethylsilane, 3- [10- (triethoxysilyl) decyl] -4-oxazoline, etc. Among these, 3- (1-hexamethyleneimino) prochyl (triethoxy) silane and (1-hexamethyleneimino) methyl (trimethoxy) silane are preferable.

  Further, examples of the acyclic tertiary amine group-containing hydrocarbyloxysilane compound include 3-dimethylaminopropyl (triethoxy) silane, 3-dimethylaminopropyl (trimethoxy) silane, 3-diethylaminopropyl (triethoxy) silane, 3-diethylaminopropyl ( Trimethoxy) silane, 2-dimethylaminoethyl (triethoxy) silane, 2-dimethylaminoethyl (trimethoxy) silane, 3-dimethylaminopropyl (diethoxy) methylsilane, 3-dibutylaminopropyl (triethoxy) silane, and the like. Of these, 3-diethylaminopropyl (triethoxy) silane and 3-dimethylaminopropyl (triethoxy) silane are preferable.

  Still other hydrocarbyloxysilane compounds include 2- (trimethoxysilylethyl) pyridine, 2- (triethoxysilylethyl) pyridine, 2-cyanoethyltriethoxysilane and the like.

  The hydrocarbyloxysilane compound of the above formula (III) may be used alone or in combination of two or more. Moreover, the partial condensate of the said hydrocarbyl oxysilane compound can also be used.

In formula (IV), R ⁶ and R ⁷ are as described for R ⁴ and R ⁵ in formula (III), respectively.

Examples of the hydrocarbyloxysilane compound represented by the formula (IV) include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, tetra -Sec-butoxysilane, tetra-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyl Trimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxy Silane, divinyl dimethoxysilane, divinyl diethoxy silane and the like, and among them, tetraethoxysilane is particularly preferred.
The hydrocarbyloxysilane compound of the formula (IV) may be used alone or in combination of two or more. Moreover, the partial condensate of these hydrocarbyl oxysilane compounds can also be used.
As the modifier, the following formula (V):
R ⁸ _a ZX (V)
[Wherein, R ⁸ each independently comprises 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 an aralkyl group having 7 to 20 carbon atoms. Selected from the group; Z is tin or silicon; X is each independently chlorine or bromine; a is 0-3, b is 1-4, provided that a + b = 4. The coupling agent represented is also preferred.
By modifying with the coupling agent of the formula (V), the cold flow resistance of the copolymer can be improved. The copolymer obtained by modification with the coupling agent of the formula (V) has at least one tin-carbon bond or silicon-carbon bond.

Specific examples of R ^{8 in the} formula (V) include a methyl group, an ethyl group, an n-butyl group, a neophyll group, a cyclohexyl group, an n-octyl group, and a 2-ethylhexyl group. Specific examples of the coupling agent of formula M include SnCl ₄ , R ⁸ SnCl ₃ , R ⁸ ₂ SnCl ₂ , R ⁸ ₃ SnCl, SiCl ₄ , R ⁸ SiCl ₃ , R ⁸ ₂ SiCl ₂ , R ⁸ ₃ SiCl, SiCl ₄ , etc. are preferred, and SnCl ₄ and SiCl ₄ are particularly preferred.

The modification reaction of the polymerization active site by the modifying agent is preferably performed by a solution reaction, and the solution may contain a monomer used at the time of polymerization. The reaction mode of the modification reaction is not particularly limited, and may be a batch type or a continuous type. Furthermore, the reaction temperature of the modification reaction is not particularly limited as long as the reaction proceeds, and the reaction temperature of the polymerization reaction may be employed as it is. In addition, the usage-amount of modifier | denaturant has the preferable range of 0.25-3.0 mol with respect to 1 mol of polymerization initiators used for manufacture of a copolymer, and the range of 0.5-1.5 mol is still more preferable.
In the present invention, after drying the reaction solution containing the copolymer and separating the copolymer, the obtained copolymer may be blended with the rubber component, or the reaction containing the copolymer. The solution may be mixed with the rubber cement of the rubber component in a solution state and then dried to obtain a mixture of the rubber component and the copolymer.

<Inorganic compound powder (C)>
The rubber composition contains 3 to 30 parts by mass of the inorganic compound powder (C) represented by the following general formula (1) with respect to 100 parts by mass of the rubber component (A). Preferably it contains in the range of 5-20 mass parts. When the inorganic compound powder (C) is blended without the above range, it exhibits excellent running stability on wet road surfaces while maintaining wear resistance as a tread rubber.
M · xSiO ₂ · yH ₂ O (1)
Here, in Formula (1), M is any of aluminum, magnesium, titanium, and calcium, and x and y are integers of 0 to 10.
The inorganic compound powder (C) represented by the formula (1) has an average particle size in the range of 10 μm or less. Preferably, it is the range of 0.05-5 micrometers. When inorganic compound powder exceeds 10 micrometers, the effect with respect to the wet skid performance as a tread rubber will be reduced.

Examples of the inorganic compound powder (C) represented by the general formula (1) include alumina (Al ₂ O ₃ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (MgO ₂ ), titanium white (TiO ₂ ). _2), titanium black (TiO _2n-1), talc (3MgO · 4SiO _2), attapulgite _{(5MgO · 8SiO 2 -H 2 O} ) , and the like. Magnesium calcium silicate (CaMgSiO ₄ ) and magnesium silicate (MgSiO ₃ ) also exhibit the same effects as the inorganic compound powder of the present invention.
Moreover, it is preferable that the inorganic compound powder represented by the general formula (1) is an inorganic compound powder represented by the following general formula (2).
Al ₂ O ₃ .mSiO ₂ .nH ₂ O (2)
M in General formula (2) is an integer of 1-4, n is an integer of 0-4.
Specific inorganic compound powders represented by the general formula (2) are clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ · 4SiO ₂ · H ₂ O), pentonite (Al ₂ O ₃ · 4SiO ₂ · 2H ₂ O) and the like. Of these, aluminum hydroxide (Al (OH) ₃ ), alumina (Al ₂ O ₃ ), and clay (Al ₂ O ₃ .2SiO ₂ ) are particularly preferable. The aluminum hydroxide used in the present invention includes alumina hydrate.
The inorganic compound powder (C) having the above characteristics can be used alone or in combination of two or more. In addition, the inorganic compound powder that does not satisfy the above conditions, for example, those having many structures such as sulfides, sulfates or carbonates selected from Al, Mg, Ti, and Ca do not improve the wet skid performance.

<Other additives>
In addition to the copolymer (B), other naphthenic and aromatic process oils (aromatic oils) and softeners such as spindle oil can be added to the rubber composition of the present invention.
The softener is supplementarily added to the copolymer (B), and the total amount of the copolymer (B) and the softener is in the range of 5 to 80 parts by mass with respect to 100 parts by mass of the rubber component (A). Especially preferably, it is good to add in the range of 10-60 mass parts. If it is less than 5, the effect of the said copolymer (B) will also reduce, and when it exceeds 80 mass parts, abrasion resistance will deteriorate.

A filler such as silica and / or carbon black (C / B) is added to the rubber composition of the present invention.
The silica mass ratio in the filler is preferably in the range of 30 to 100 mass%, particularly preferably in the range of 50 to 100 mass%. When the silica mass ratio in the filler is less than 30% by mass, it becomes difficult to achieve both braking performance, particularly wet braking performance and low rolling resistance.
The filler carbon black (C / B) is preferably a carbon black such as HAF, ISAF, or SAF. The total content of the filler in the rubber composition is preferably 40 to 100 parts by mass with respect to 100 parts by mass of the rubber component, and if it is less than 40 parts by mass, the elastic modulus decreases and the steering stability of the tire decreases. If it exceeds 100 parts by mass, the heat build-up will deteriorate and the durability of the tire will decrease.
Further, in the rubber composition of the present invention, fatty acids such as stearic acid conventionally used may be used in addition to the above copolymer. The composition of the present invention can contain a silane coupling agent, an anti-aging agent, a vulcanization accelerator, zinc white, sulfur and the like in addition to the above-described composition.

  The pneumatic tire of the present invention is produced by a usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into a tread member at an unvulcanized stage, and pasted and molded by a normal method on a tire molding machine. A green tire is formed. The green tire is heated and pressed in a vulcanizer to obtain a tire. The pneumatic tire of the present invention thus obtained is excellent in wet skid performance and low rolling resistance (low heat generation). An inert gas such as nitrogen may be introduced into the pneumatic tire.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
<Production example of copolymer (B)>
To an 800 mL pressure-resistant glass container that has been dried and purged with nitrogen, 300 g of cyclohexane, 40 g of 1,3-butadiene, 13 g of styrene, and 0.90 mmol of ditetrahydrofurylpropane were added, and n-butyllithium (n-BuLi) 0. After adding 90 mmol, a polymerization reaction was carried out at 50 ° C. for 2 hours. The polymerization conversion rate at this time was almost 100%. Next, the modifier shown in the following Table 1 as a modifier was quickly added to the polymerization reaction system in the amount shown in Table 1, and a modification reaction was further performed at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction. To obtain copolymers 1 to 4. The mass average molecular weight (Mw), microstructure, and bound styrene content of the copolymers 1 to 4 produced as described above were measured by the following methods. The results are shown in Table 1.

(1) Mass average molecular weight (Mw)
Gel permeation chromatography [GPC: Tosoh HLC-8020, column: Tosoh GMH-XL (two in series), detector: differential refractometer (RI)], based on monodisperse polystyrene, The weight average molecular weight (Mw) in terms of polystyrene was determined.
(2) Vinyl content The vinyl content of the polymer was determined by an infrared method (Morero method).
(3) Bonded styrene content The styrene content of the polymer was determined by 270 MHz ¹ H-NMR.
(4) Glass transition point Using a differential thermal analyzer (DSC) 7 type apparatus manufactured by PerkinElmer, Inc., each polymer was cooled to -100 ° C, and then heated at a rate of temperature increase of 10 ° C / min. The glass transition point of the polymer was measured.

  In the production example of copolymer 5, a polymerization reaction is carried out in the same manner as in the production examples of copolymers 1 to 4, and after completion of the polymerization reaction, a modification reaction is not carried out. 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of t-butyl-p-cresol (BHT) was added to terminate the polymerization reaction, and further dried according to a conventional method to obtain a copolymer 1.

Copolymers 6 and 8 to 13 were produced as follows.
To an 800 mL pressure-resistant glass container that has been dried and purged with nitrogen, 300 g of cyclohexane, 40 g of 1,3-butadiene, 13 g of styrene, and 0.90 mmol of ditetrahydrofurylpropane were added, and n-butyllithium (n-BuLi) 0. After adding 90 mmol, a polymerization reaction was carried out at 50 ° C. for 2 hours. The polymerization conversion rate at this time was almost 100%. Next, the modifiers shown in Tables 2 and 3 below were quickly added to the polymerization reaction system in the amounts shown in Tables 2 and 3, followed by a modification reaction at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction. To obtain copolymers 6, 8 to 13. The weight average molecular weight (Mw), microstructure, and bound styrene content of the copolymers 6 and 8 to 13 produced as described above were measured by the above methods. The results are shown in Tables 2 and 3.

Copolymer 7 was produced as follows.
Instead of N-butyllithium (n-BuLi) as a polymerization initiator, lithium hexamethyleneimide prepared in situ [HMI-Li; hexamethyleneimine (HMI) / lithium (Li) molar ratio = 0.9 The copolymer 7 was obtained in the same manner as the copolymer 5 except that the lithium equivalent was 0.9 mmol. Shown in Table 2 above.

Further, copolymers 14 and 15 were produced as follows.
Instead of N-butyllithium (n-BuLi) as a polymerization initiator, lithium hexamethyleneimide prepared in situ [HMI-Li; hexamethyleneimine (HMI) / lithium (Li) molar ratio = 0.9 Copolymers 14 and 15 were obtained in the same manner as Copolymers 8 and 10 except that lithium was used at 0.9 mmol in terms of lithium. Shown in Table 3 above. In addition, * 1-8 in a table | surface is the following.

* 1 Tetraethoxysilane.
* 2 N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine.
* 3 Diphenylmethane-4,4-diisocyanate (crude MDI, MR-400 manufactured by Nippon Polyurethane).
* 4 N, N′-diethylaminobenzophenone.
* 5 Dimethylimidazolidinone.
* 6 N-methylpyrrolidone.
* 7 4-Dimethylaminobenzylideneaniline.
* 8 4-dimethylaminobenzylidenebutylamine.

  Next, the above copolymers (B) 1 to 15 and / or aroma oil are converted into rubber component (A) copolymer rubber; # 1500 ((Emulsion polymerization SBR mass average molecular weight 450,000) manufactured by JSR Corporation). (Styrene amount (St) / vinyl amount (Vi) = 23.5% by mass / 18%)] and the inorganic compound powder (C) has an average particle size of 0.75 μm and a particle size of 5 μm or less. Using aluminum hydroxide (trade name “Hijilite H-43” manufactured by Showa Denko KK), rubber compositions having the formulation shown in Tables 4 to 6 below were prepared. This was used as a tire tread and vulcanized to produce a test tire, which was subjected to the following low heat generation performance and wet skid performance test. The results are shown in Tables 4-6.

(1) Low heat generation performance (low rolling resistance performance)
A sample obtained by vulcanizing the rubber composition was evaluated with a low exothermic index by an exothermic test. In the exothermic test, tan δ was determined using a spectrometer (dynamic strain amplitude 0.1%, frequency 52 Hz, measurement temperature 25 ° C.) manufactured by Toyo Seiki Co., Ltd., and calculated according to the following formula. Low exothermic index = (tan δ of the test piece of Comparative Example 1) / (tan δ of the test piece of Guo, etc.) Here, the larger the low exothermic index, the better the low exothermic property.
(2) Wet skid performance Four test tires (tire size 185 / 70R15) mounted on a domestic 1600CC class passenger car, braking distance at initial speed of 40, 60, and 80 km / h on wet asphalt road surface The tire of Comparative Example 1 was used as a control tire, and braking performance = (braking distance at each speed in Comparative Example 1 / distance at each corresponding speed in each example) × 100. The larger the value, the better the braking performance.

In addition, * 11-17 in a table | surface is the following.
* 11 Tokai Carbon Co., Ltd., trademark: Seast KH (N339).
* 12 Nipsil AQ (manufactured by Tosoh Silica Corporation).
* 13 Bis (3-triethoxysilylpropyl) tetrasulfide Si69 (Degussa).
* 14 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine.
* 15 Diphenylguanidine.
* 16 Benzothiazyl disulfide.
* 17 Nt-butyl-2-benzothiazylsulfenamide.
By using aluminum hydroxide powder, wet skid performance is improved with respect to Comparative Example 1-4, and combined with this, by using copolymer (B) instead of aroma oil, wet skid performance is improved. Low exothermicity is improved while maintaining.

  The present invention improves the characteristics of the rubber composition used in the tread portion, and is excellent in running stability on a wet road surface and low rolling resistance (low heat generation) without impairing contradictory performance such as steering stability. It is a pneumatic tire with high industrial applicability.

FIG. 1 is a schematic sectional view of a general pneumatic tire.

Claims (12)

An aromatic vinyl having a weight average molecular weight (polystyrene conversion measured by gel permeation chromatography) in the range of 5,000 to 500,000 and containing a functional group with respect to 100 parts by mass of the rubber component (A). The compound-conjugated diene compound copolymer (B) is contained in the range of 2 to 60 parts by mass, and the metal oxide or metal hydroxide represented by the following general formula (1) and hydrates thereof A rubber composition comprising an inorganic compound powder (C) composed of at least one kind and having an average particle diameter of 10 μm or less in a range of 3 to 30 parts by mass.
M · xSiO ₂ · yH ₂ O (1) [wherein, in formula (1), M is any one of aluminum, magnesium, titanium, and calcium, and x and y are 0-10. It is an integer. ]   The copolymer (B) is composed of 5 to 80% by mass of an aromatic vinyl compound, and the vinyl bond content of the conjugated diene compound portion of the copolymer (B) is 10 to 80% by mass. The rubber composition according to claim 1.   The aromatic vinyl compound-conjugated diene compound copolymer (B) is at least one modified functional group-containing copolymer selected from a tin-containing functional group, a silicon-containing functional group, and a nitrogen-containing functional group. The rubber composition according to claim 1.   The rubber composition according to claim 3, wherein the nitrogen-containing functional group is at least one selected from a substituted or unsubstituted amino group, an amide group, an imino group, an imidazole group, a nitrile group, and a pyridyl group.   The rubber composition according to claim 1, wherein the rubber component (A) contains 50% by mass or more of styrene-butadiene copolymer rubber.   The rubber composition according to claim 1, wherein the aromatic vinyl compound in the aromatic vinyl compound-conjugated diene compound copolymer (B) is styrene.   The rubber composition according to claim 1, wherein the conjugated diene compound in the aromatic vinyl compound-conjugated diene compound copolymer (B) is 1,3-butadiene.   The rubber composition according to claim 1, wherein the aromatic vinyl compound-conjugated diene compound copolymer (B) has a mass average molecular weight (in terms of polystyrene measured by gel permeation chromatography) in the range of 20,000 to 400,000. object.   The aromatic vinyl compound-conjugated diene compound polymer (B) has a mass average molecular weight (polystyrene conversion measured by gel permeation chromatography) before introducing a functional group in the range of 5,000 to 200,000. Item 2. The rubber composition according to Item 1. The rubber composition according to claim 1, wherein the inorganic compound powder (C) represented by the general formula (1) is an inorganic compound powder represented by the following general formula (2).
Al ₂ O ₃ mSi ₂ .nH ₂ O (2) [wherein, m is an integer of 1 to 4 and n is an integer of 0 to 4 in the formula (2). ]   The rubber composition according to claim 10, wherein the inorganic compound powder (C) represented by the general formula (2) is an aluminum hydroxide powder.   A pneumatic tire using the rubber composition according to any one of claims 1 to 11 for at least a ground contact portion of a tire tread portion.

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