JP2004238619A - Rubber composition and studless tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber composition excellent in on-ice and -snow performance and durability under heat-buildup and to provide a studless tire excellent in on-ice and -snow performance and durability under heat-buildup using the rubber composition as a tread rubber. <P>SOLUTION: The rubber composition is obtained by compounding a rubber component with a foaming agent, its expansion ratio after vulcanization is 5-30%, and its dynamic elastic modulus is 30 MPa or below at 0°C and 7 MPa or above at 60°C, respectively. The studless tire uses this rubber composition as the tread rubber. The rubber composition desirably has a tanδ of 0.25 or below at 60°C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a rubber composition and a studless tire using the rubber composition for a tread rubber, and more particularly to a rubber composition and a studless tire having excellent performance on ice and snow and durability against heat generation.

  Conventional studless tires have a low glass transition point (Tg) to improve the performance on ice and snow, and have a low temperature (here, the low temperature is a temperature at the time of running on ice and snow and is about -20 to 0 ° C). In many cases, the elastic modulus is set low. However, since the elastic modulus at low temperatures generally tends to decrease when the elastic modulus at low temperatures decreases, conventional studless tires have high heat build-up and rolling resistance (RR), and heat endurance and rolling resistance are low in the market. Has not been able to adequately meet the requirements of

  In general, the heat generation durability does not become a significant problem in a studless tire for a passenger car with a small load, even if the elastic modulus is lowered. Therefore, even a studless tire that emphasizes performance on ice and snow, it is necessary to ensure a certain level of heat generation durability.

  On the other hand, in order to secure heat durability, a technique has been disclosed in which only the heat generated by the base rubber is reduced in a tread having a cap-base structure (see Patent Document 1). In addition, a method of increasing the ratio of the base rubber in the tread having the cap-base structure to reduce the heat generation of the entire tread can be considered.

JP-A-6-227 211

  However, even if only the heat generation of the base rubber is reduced, there is a limit in reducing the heat generation of the tread as a whole, and in general, the lower the heat generation of the base rubber, the lower the abrasion resistance. Therefore, there is a problem that the wear resistance when the base rubber is exposed becomes insufficient.

  In addition, when the ratio of the base rubber is increased, the ratio of the cap rubber is inevitably reduced, and the exposure of the base rubber accompanying the progress of tread wear is accelerated, so that stable performance on ice and snow is maintained until the end of wear. There is a problem that is difficult.

  Then, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a rubber composition excellent in performance on ice and snow and durability against heat generation, and a studless tire using the rubber composition for tread rubber.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, a foaming agent was added to the rubber component, and the foaming rate after vulcanization and the dynamic elastic modulus at 0 ° C and 60 ° C were specified. It has been found that the use of the rubber composition in the above range for the tire tread rubber improves the performance of the tire on ice and snow and the durability against heat generation, and has completed the present invention.

  That is, the rubber composition of the present invention is obtained by blending a foaming agent with a rubber component, has a foaming rate after vulcanization of 5 to 30%, a dynamic elastic modulus at 0 ° C of 30 MPa or less and 60 ° C. Wherein the dynamic modulus of elasticity is 7 MPa or more.

  In a preferred example of the rubber composition of the present invention, tan δ (loss tangent) at 60 ° C. is 0.25 or less.

  In another preferred embodiment of the rubber composition of the present invention, the rubber composition contains short fibers made of a thermoplastic resin, and when the short fibers are vulcanized, the temperature of the rubber composition reaches the maximum vulcanization temperature. It melts or softens in the matrix of the rubber composition before reaching. Here, it is more preferable that the short fibers have a diameter of 0.03 to 0.3 mm and a length of 1 to 10 mm. Further, it is more preferable that the short fiber is made of a crystalline polymer and has a melting point of 100 to 190 ° C or an amorphous polymer and a softening point of 100 to 190 ° C. When the rubber composition contains short fibers, it is particularly preferable that at least most of the bubbles generated during vulcanization are long and vulcanized in a certain direction after vulcanization.

  In another preferred embodiment of the rubber composition of the present invention, the rubber component contains a terminal-modified conjugated diene-based polymer. Here, the terminal-modified conjugated diene-based polymer is obtained by polymerizing a conjugated diene-based monomer alone or together with another monomer, and has a content of cis-1,4-bond in the conjugated diene portion of the main chain. It is more preferable that 75 mol% or more of the conjugated diene-based polymer having an active terminal is obtained by modifying the active terminal with a modifying agent. Further, the terminal-modified conjugated diene-based polymer is a saccharide having 4 or more carbon atoms after the first modification in which a hydrocarbyloxysilane compound is reacted with the active terminal of the conjugated diene-based polymer having the active terminal. A fatty acid ester of a polyhydric alcohol containing a modified saccharide and a compound having at least one hydroxyl group, and a compound produced by performing a second modification by reacting at least one compound selected from the group consisting of a hydrocarbyloxysilane compound. Is particularly preferred.

Here, a condensation accelerator is used in the second modification, and the condensation accelerator preferably comprises water and at least one selected from the group consisting of metal compounds represented by the following (1) to (3). .
(1) Tin carboxylate having 3 to 30 carbon atoms and having an oxidation number of 2 and satisfying the following formula: Sn (OCOR ¹⁴ ) ₂
(In the formula, R ¹⁴ is an organic group having 2 to 19 carbon atoms, and when there are a plurality of them, they may be the same or different.)
(2) Tin compounds having an oxidation number of 4 and satisfying the following formula: R ¹⁵ _r SnA ⁴ _t B ¹ _(4-tr)
[In the formula, r is an integer of 1 to 3; t is an integer of 1 or 2; t + r is an integer of 3 or 4. R ¹⁵ is an aliphatic hydrocarbon group having 1 to 30 carbon atoms; B ¹ is a hydroxyl group or a halogen. A ⁴ represents (i) a carboxyl group having 2 to 30 carbon atoms, (ii) an α, γ-dionyl group having 5 to 30 carbon atoms, (iii) a hydrocarbyloxy group having 3 to 30 carbon atoms, and (iv) A group selected from siloxy groups which are totally trisubstituted (may be the same or different) with a hydrocarbyl group having 1 to 20 and / or a hydrocarbyloxy group having 1 to 20 carbon atoms, and when there are a plurality of A ^4, They may be the same or different. ]
(3) A titanium compound having an oxidation number of 4 and satisfying the following formula: A ⁵ _x TiB ² _(4-x)
(In the formula, x is an integer of 2 or 4. A ⁵ is (i) an alkoxy group having 3 to 30 carbon atoms, (ii) an alkyl group having 1 to 30 carbon atoms and / or an alkyl group having 1 to 20 carbon atoms. the sum trisubstituted siloxy group with an alkoxy group, .B ² may be the same or different if a ⁵ there are multiple, alpha of 5 to 30 carbon atoms, a γ- dionyl group.)

The polymerization catalyst used for the polymerization of the conjugated diene polymer is preferably a combination of at least one compound selected from the following components (A), (B) and (C).
Component (A): a rare earth compound selected from the following (A1) to (A4), which may be used directly as an inert organic solvent solution or supported on an inert solid.
(A1) A rare earth compound having an oxidation number of 3, which is a carboxyl group having 2 to 30 carbon atoms, an alkoxy group having 2 to 30 carbon atoms, an aryloxy group having 6 to 30 carbon atoms, and an α, γ-diketonyl having 5 to 30 carbon atoms. Having a total of three ligands selected from the groups, or a complex compound of this with a Lewis base compound
(A2) Complex compound of rare earth trihalide and Lewis base
(A3) An organic rare earth compound having an oxidation number of 3, wherein at least one (substituted) allyl group is directly bonded to a rare earth atom
(A4) An organic rare earth compound having an oxidation number of 2 or 3 in which at least one (substituted) cyclopentadienyl group is directly bonded to a rare earth atom, or an ion comprising this compound and a trialkylaluminum or a non-coordinating anion and a counter cation Reaction product (B) component with a reactive compound: at least one type of organoaluminum compound selected from the following ones, and a plurality of them can be used simultaneously
(B1) R ³ ₃ trihydrocarbyl aluminum compound represented by Al (where, R ³ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other)
(B2) R ⁴ ₂ AlH or hydrocarbyl aluminum hydride represented by R ⁴ AlH ₂ (where, R ⁴ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other)
(B3) a hydrocarbylaluminoxane compound having a hydrocarbon group having 1 to 30 carbon atoms (C) component: a compound selected from the following, wherein (A) contains a halogen or a non-coordinating anion, and ( Not necessary when B) contains aluminoxane
(C1) Group II, III, IV inorganic or organic compounds having at least one hydrolyzable halogen or complex compounds thereof with Lewis bases
(C2) an organic halide having a structure selected from at least one tertiary alkyl halide, benzyl halide, and allyl halide
(C3) a zinc halide or a complex compound thereof with a Lewis base
(C4) Ionic compound consisting of non-coordinating anion and counter cation

  The rare earth element is particularly preferably at least one selected from the group consisting of lanthanum, neodymium, praseodymium, samarium, and gadolinium.

  Further, the conjugated diene-based polymer is particularly preferably at least one selected from the group consisting of polybutadiene, polyisoprene, and a copolymer of butadiene and another conjugated diene.

（式中、Ｒ¹は、それぞれ独立して炭素数１〜１２のアルキル基、シクロアルキル基又はアラルキル基である）で表される置換アミノ基、及び下記式(II)：

（式中、Ｒ²は、３〜１６のメチレン基を有するアルキレン基、置換アルキレン基、オキシアルキレン基又はＮ-アルキルアミノ-アルキレン基を示す）で表される環状アミノ基からなる群から選択された少なくとも一種の官能基を有する変性共役ジエン系重合体も好ましい。ここで、該変性共役ジエン系重合体は、ブタジエン部のビニル結合量が30％以下であるのが特に好ましく、前記ビニル芳香族化合物の結合量が20質量％以下であるのが特に好ましい。また、該変性共役ジエン系重合体は、スチレン・ブタジエン共重合体又はポリブタジエンであるのが特に好ましい。更に、該変性共役ジエン系重合体は、ガラス転移温度（Ｔg）が-50℃以下であるのが好ましい。 Further, the terminal-modified conjugated diene-based polymer is a copolymer of butadiene and a vinyl aromatic compound or a homopolymer of butadiene, and has the following formula (I):

(Wherein R ¹ is independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aralkyl group), and the following formula (II):

(Wherein, R ² represents an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group). A modified conjugated diene polymer having at least one functional group is also preferable. Here, in the modified conjugated diene polymer, the vinyl bond amount in the butadiene portion is particularly preferably 30% or less, and the bond amount of the vinyl aromatic compound is particularly preferably 20% by mass or less. The modified conjugated diene polymer is particularly preferably a styrene / butadiene copolymer or polybutadiene. Further, the modified conjugated diene polymer preferably has a glass transition temperature (Tg) of -50 ° C or lower.

In the substituted amino group represented by the formula (I), R ¹ is preferably a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, a 3-phenyl-1-propyl group, and an isobutyl group.

In the cyclic amino group represented by the formula (II), R ² is preferably a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, or a hexadecamethylene group.

  Further, a studless tire of the present invention is characterized in that the above rubber composition is used for a tread rubber. Here, the studless tire is preferably a heavy load studless tire.

  In a preferred example of the studless tire of the present invention, the rubber composition used for the tread rubber contains short fibers, and at least most of the air bubbles after vulcanization are long and substantially oriented in the tire circumferential direction. ing.

  ADVANTAGE OF THE INVENTION According to this invention, a foaming rate and a dynamic elastic modulus are in a specific range, and the rubber composition excellent in performance on ice and snow and heat generation durability can be provided. Further, the studless tire of the present invention using the rubber composition for a tread rubber is excellent in performance on ice and snow and durability against heat generation.

  Hereinafter, the present invention will be described in detail. The rubber composition of the present invention is obtained by blending a foaming agent with a rubber component, has a foaming rate after vulcanization of 5 to 30%, a dynamic elastic modulus at 0 ° C. (E ′) of 30 MPa or less, and A dynamic elastic modulus (E ') at 60 ° C. is 7 MPa or more. If the foaming rate of the rubber composition after vulcanization is less than 5%, the performance on ice and snow cannot be sufficiently ensured, and if it exceeds 30%, the abrasion resistance is remarkably inferior and not only is not practically preferable, but also the elastic modulus decreases. Then, the dynamic elastic modulus at 60 ° C. tends to be less than 7 MPa. Further, the rubber composition of the present invention has a dynamic elastic modulus at 0 ° C. of 30 MPa or less, so that it is pliable even at a low temperature, and sufficient performance on ice and snow can be secured. From the viewpoint of further improving the performance on ice and snow, the rubber composition preferably has a dynamic elastic modulus at 0 ° C. of 25 MPa or less. Furthermore, since the rubber composition of the present invention has a dynamic elastic modulus at 60 ° C. of 7 MPa or more, a tire using the rubber composition for a tread has a high block rigidity of the tread during normal running on ice and snow. In addition, since the block deformation during rolling is suppressed, heat generation is reduced, and as a result, heat generation durability is high. From the viewpoint of further reducing heat generation and further improving heat generation durability, the rubber composition preferably has a dynamic elastic modulus at 60 ° C. of 9 MPa or more. Further, the rubber composition of the present invention preferably has a tan δ (loss tangent) at 60 ° C. of 0.25 or less from the viewpoint of reducing heat generation of the rubber composition itself.

The foaming rate (Vs) after vulcanization of the rubber composition needs to be in the range of 5 to 30%. Here, the foaming ratio (Vs) can be calculated by the following equation.
Vs = (ρ ₀ / ρ ₁ -1) × 100 (%)
(Wherein, [rho ₁ represents the density of the rubber composition after vulcanization ^{(g / cm 3), ρ} 0 represents the density of the solid phase portion in the rubber composition after vulcanization (g / cm ^3). )

  The density of the rubber composition after vulcanization and the density of the solid phase portion in the rubber composition after vulcanization are calculated from the mass in ethanol and the mass in air. Further, the foaming ratio (Vs) can be appropriately changed depending on the types and amounts of the foaming agent and the foaming assistant described later.

  Examples of the rubber component used in the rubber composition of the present invention include diene rubbers such as natural rubber (NR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), and polyisoprene rubber (IR). However, there is no particular limitation as long as it has the above physical properties. The rubber component may be a single kind or a blend of two or more kinds. The rubber component preferably contains a terminal-modified conjugated diene polymer. When the rubber component contains a terminal-modified conjugated diene-based polymer, it is particularly effective in reducing the dynamic elastic modulus (E ') at 0 ° C and the tan δ.

  The terminal-modified conjugated diene-based polymer is obtained by polymerizing a conjugated diene-based monomer alone or together with another monomer, and has a cis-1,4-bond content of 75 mol in the conjugated diene portion of the main chain. % Or more of the conjugated diene-based polymer having an active terminal, wherein the active terminal is modified with a modifier. Here, examples of the modifier include a hydrocarbyloxysilane compound.

  Examples of the method for producing a polymer having an active terminal having a cis-1,4 bond content of 75% or more include a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method. preferable. Further, the polymerization system may be any of a batch system and a continuous system.

  Examples of the conjugated diene-based monomer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. Among them, 1,3-butadiene is particularly preferred. These conjugated diene monomers may be used alone or in combination of two or more. Although a small amount of another hydrocarbon monomer may be allowed to coexist with these conjugated diene-based monomers, the content of the conjugated diene-based monomer is preferably at least 80 mol% of all the monomers.

  In the production of a polymer having an active terminal having a cis-1,4 bond content of 75% or more, at least one compound selected from the following components (A), (B) and (C) is used as a polymerization catalyst. Are preferred.

Component (A): a rare earth compound selected from the following (A1) to (A4), which may be used as it is as an inert organic solvent solution or may be supported on an inert solid.
(A1) A rare earth compound having an oxidation number of 3, which is a carboxyl group having 2 to 30 carbon atoms, an alkoxy group having 2 to 30 carbon atoms, an aryloxy group having 6 to 30 carbon atoms, and an α, γ-diketonyl having 5 to 30 carbon atoms. Having a total of three ligands freely selected from groups, or a Lewis base compound (in particular, free carboxylic acid, free alcohol, α, γ-diketone, cyclic ether, linear ether, trihydrocarbyl) Phosphine, trihydrocarbyl phosphite, etc.). Specific examples include neodymium tri-2-ethylhexanoate, a complex compound thereof with acetylacetone, neodymium trinedecanoate, a complex compound thereof with acetylacetone, neodymium tri-n-butoxide, and the like.
(A2) A complex compound of a rare earth trihalide and a Lewis base. For example, there is a THF complex of neodymium trichloride.
(A3) An organic rare earth compound having an oxidation number of 3, in which at least one (substituted) allyl group is directly bonded to a rare earth atom. For example, a salt of tetraallyl neodymium and lithium is given.
(A4) An organic rare earth compound having an oxidation number of 2 or 3 in which at least one (substituted) cyclopentadienyl group is directly bonded to a rare earth atom, or an ion comprising this compound and a trialkylaluminum or a non-coordinating anion and a counter cation It is a reaction product with a reactive compound. For example, dimethylaluminum (μ-dimethyl) bis (pentamethylcyclopentadienyl) samarium can be mentioned.

  As the rare earth element of the rare earth compound, lanthanum, neodymium, praseodymium, samarium, and gadolinium are preferable, and among these, lanthanum, neodymium, and samarium are more preferable. Among the above components (A), a carboxylate of neodymium and a substituted cyclopentadienyl compound of samarium are preferred.

Component (B): at least one type of organoaluminum compound selected from the following ones, and a plurality of them can be used simultaneously.
(B1) R ³ ₃ trihydrocarbyl aluminum compound represented by Al (where, R ³ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other).
(B2) R ⁴ ₂ AlH or hydrocarbyl aluminum hydride represented by R ⁴ AlH ₂ (where, R ⁴ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other).
(B3) A hydrocarbylaluminoxane compound having a hydrocarbon group having 1 to 30 carbon atoms.

  Examples of the component (B) include trialkylaluminum, dialkylaluminum hydride, alkylaluminum dihydride, and alkylaluminoxane. These compounds may be used as a mixture. Among the components (B), a combination of an aluminoxane and another organic aluminum compound is preferred.

Component (C): a compound selected from the following, but is not necessarily required when (A) contains a halogen or a non-coordinating anion, and when (B) contains an aluminoxane.
(C1) Inorganic or organic compounds of groups II, III and IV having a hydrolyzable halogen or complex compounds thereof with Lewis bases. Examples thereof include alkylaluminum dichloride, dialkylaluminum chloride, silicon tetrachloride, tin tetrachloride, a complex of zinc chloride with a Lewis base such as an alcohol, a complex of magnesium chloride with a Lewis base such as an alcohol, and the like.
(C2) An organic halide having a structure selected from at least one tertiary alkyl halide, benzyl halide, and allyl halide. For example, benzyl chloride, t-butyl chloride, benzyl bromide, t-butyl bromide and the like can be mentioned.
(C3) A zinc halide or a complex compound thereof with a Lewis base.
(C4) An ionic compound comprising a non-coordinating anion and a counter cation. An example is triphenylcarbonium tetrakis (pentafluorophenyl) borate.

  The preparation of the catalyst is carried out by preliminarily using the same conjugated diene-based monomer and / or non-conjugated diene-based monomer as the polymerization monomer, if necessary, in addition to the components (A), (B) and (C). May be used. Further, a part or all of the component (A) or the component (C) may be supported on an inert solid and used, and in this case, it can be carried out by so-called gas phase polymerization. The amount of the catalyst to be used can be appropriately set, but the component (A) is usually 0.001 to 0.5 mmol per 100 g of the monomer. The molar ratio of component (B) / component (A) is 5 to 1000, and the ratio of component (C) / component (A) is 0.5 to 10.

  Examples of the solvent used in the solution polymerization include organic solvents inert to the reaction, for example, hydrocarbon solvents such as aliphatic, alicyclic, and aromatic hydrocarbon compounds. Specifically, those having 3 to 8 carbon atoms are preferable, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, Cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or as a mixture of two or more.

  The temperature in the above-mentioned polymerization reaction is preferably selected within a range of -80 to 150 ° C, more preferably -20 to 120 ° C. The polymerization reaction can be carried out under the pressure generated, but it is usually desirable to operate at a pressure sufficient to keep the monomer in a substantially liquid phase. That is, the pressure will depend on the particular material being polymerized, the polymerization medium used and the polymerization temperature, but higher pressures can be used if desired, and such pressures are maintained in the reactor with an inert gas for the polymerization reaction. Is obtained by an appropriate method such as pressing. In this polymerization reaction, it is desirable to use, as all raw materials involved in the polymerization of the catalyst, the solvent, the monomer, and the like, those from which reaction inhibitors such as water, oxygen, carbon dioxide, and protic compounds have been substantially removed.

  The terminal-modified conjugated diene-based polymer has a carbon number after the first modification in which a hydrocarbyloxysilane compound is reacted with the active terminal of the conjugated diene-based polymer having an active terminal obtained as described above. Performing a second modification by reacting a fatty acid ester of a polyhydric alcohol containing four or more saccharides or modified saccharides and having at least one compound selected from the group consisting of a compound having at least one hydroxyl group and a hydrocarbyloxysilane compound; It is particularly preferred that they are produced by

  The terminal-modified conjugated diene polymer produced through the above-mentioned primary modification and secondary modification is modified in two modes, namely, (1) reacting a hydrocarbyloxysilane compound with an active terminal of the polymer. And then reacting with a carboxylic acid partial ester compound of a polyhydric alcohol containing a saccharide having 4 or more carbon atoms or a modified saccharide, (2) reacting a hydrocarbyloxy silane compound (silicon compound) with the active terminal of the polymer. Thereafter, a method is preferred in which a condensation accelerator is further added to carry out a condensation reaction between the residual silicon compound residue introduced at the terminal and the remaining or newly added silicon compound. In the above modification reaction, the polymer used is preferably one in which at least 10% of the polymer chains have a living property.

  In the modification methods (1) and (2), the hydrocarbyloxysilane compound used for the reaction with the active terminal of the polymer may be, for example, a hydrocarbyloxysilane compound represented by the following formula (III) and / or Partial condensates can be used.

［式中、Ａ¹は(チオ)エポキシ、(チオ)インシアネート、(チオ)ケトン、(チオ)アルデヒド、イミン、アミド、イソシアヌル酸トリエステル、(チオ)カルボン酸ヒドロカルビルエステル、(チオ)カルボン酸の金属塩、カルボン酸無水物、カルボン酸ハロゲン化物及び炭酸ジヒドロカルビルエステルの中から選ばれる少なくとも一種の官能基を有する一価の基で；Ｒ⁵は単結合又は二価の不活性炭化水素基で；Ｒ⁶及びＲ⁷は、それぞれ独立に炭素数１〜２０の一価の脂肪族炭化水素基又は炭素数６〜１８の一価の芳香族炭化水素基で；ｎは０〜２の整数であり；ＯＲ⁷が複数ある場合、複数のＯＲ⁷はたがいに同一でも異なっていてもよく；また分子中には活性プロトン及びオニウム塩は含まれない。］

[Wherein, A ¹ represents (thio) epoxy, (thio) incyanate, (thio) ketone, (thio) aldehyde, imine, amide, isocyanuric acid triester, (thio) carboxylic acid hydrocarbyl ester, (thio) carboxylic acid A monovalent group having at least one functional group selected from metal salts, carboxylic anhydrides, carboxylic acid halides and dihydrocarbyl carbonates of the formula: R ⁵ is a single bond or a divalent inert hydrocarbon group 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; n is an integer of 0 to 2 in it; If oR ⁷ there are a plurality or different and a plurality of oR ⁷ is each; for also in the molecule does not include an active proton and an onium salt. ]

Encompasses In the formula (III), the in functional groups in A ^1, imine ketimine, aldimine, include amidine, a (thio) carboxylic acid esters, unsaturated carboxylic acid esters such as acrylates and methacrylates. Examples of the metal of the metal salt of (thio) carboxylic acid include alkali metals, alkaline earth metals, Al, Sn, Zn, and the like.

As the divalent inert hydrocarbon group of R ⁵ , an alkylene group having 1 to 20 carbon atoms is preferable. The alkylene group may be linear, branched, or cyclic, but is preferably a linear one. 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 ⁶ and R ⁷ 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, and include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl And cyclohexenyl groups. Further, 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. Further, 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.

  n is an integer of 0 to 2, preferably 0, and it is necessary that this molecule has no active proton or onium salt.

  Examples of the hydrocarbyloxysilane compound represented by the formula (III) include, for example, 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 replacing epoxy group in these compounds with thioepoxy group Among these, among them, Particularly preferred are 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

  As imine group-containing hydrocarbyloxysilane compounds, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N- (1-methylethylidene) -3- (triethoxy) (Silyl) -1-propanamine, N-ethylidene-3- (triethoxysilyl) -1-propanamine, N- (1-methylpropylidene) -3- (triethoxysilyl) -1-propanamine, N- (4-N, N-dimethylaminobenzylidene) -3- (triethoxysilyl) -1-propanamine, N- (cyclohexylidene) -3- (triethoxysilyl) -1-propanamine and their triethoxy Examples thereof include trimethoxysilyl compounds, methyldiethoxysilyl compounds, ethyldiethoxysilyl compounds, methyldimethoxysilyl compounds, and ethyldimethoxysilyl compounds corresponding to silyl compounds. However, among these, N- (1-methylpropylidene) -3- (triethoxysilyl) -1-propanamine and N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1 -Propanamine is particularly preferred.

  Further, other hydrocarbyloxysilane compounds include the following. That is, as the imine (amidine) group-containing compound, 1- [3- (triethoxysilyl) propyl] -4,5-dihydroimidazole, 1- [3- (trimethoxysilyl) propyl] -4,5-dihydro Examples thereof include imidazole, 3- [10- (triethoxysilyl) decyl] -4-oxazoline, and among these, 3- (1-hexamethyleneimino) propyl (triethoxy) silane, (1-hexamethylene) Preferred are imino) methyl (trimethoxy) silane, 1- [3- (triethoxysilyl) propyl] -4,5-dihydroimidazole and 1- [3- (trimethoxysilyl) propyl] -4,5-dihydroimidazole. Also, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole, N- (3-isopropoxysilylpropyl) -4,5-dihydroimidazole, N- (3-methyldiethoxysilylpropyl)- Examples thereof include 4,5-dihydroimidazole, and among them, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole is preferable.

  Examples of the carboxylic acid ester group-containing compound include 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriisosilane. Examples thereof include propoxysilane, and among these, 3-methacryloyloxypropyltrimethoxysilane is preferable.

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

  Still further, examples of the carboxylic 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 preferred.

  These hydrocarbyloxysilane compounds may be used alone or in a combination of two or more. Further, a partial condensate of the above hydrocarbyloxysilane compound can also be used.

  In the modification method (1), after the terminal of the polymer having an active terminal and the hydrocarbyloxysilane compound first react with each other, a fatty acid ester of a polyhydric alcohol containing a saccharide having 4 or more carbon atoms or a modified saccharide is used. A compound having one or more hydroxyl groups is added and reacted. Such esters include (i) monoesters, diesters and triesters of a saturated higher fatty acid or unsaturated higher fatty acid having 10 to 20 carbon atoms and a polyhydric alcohol, and (ii) a portion of a polyhydric carboxylic acid and a higher alcohol. An ester compound in which one to three esters are bonded to a polyhydric alcohol is preferred.

  Examples of the polyhydric alcohol as a raw material for the fatty acid ester compound of the polyhydric alcohol include saccharides having 5 or 6 carbon atoms and having 5 or 6 carbon atoms (which may or may not be hydrogenated), glycols and the like. Polyhydroxy compounds and the like are preferred. Moreover, as a fatty acid, a C10-C20 saturated or unsaturated fatty acid, for example, stearic acid, lauric acid, and palmitic acid, are preferable. Among the fatty acid ester compounds of polyhydric alcohols, sorbitan fatty acid esters are preferable. For example, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate and sorbitan triolein Acid esters and the like. Commercial products include SPAN60 (trademark: sorbitan monooleate), SPAN80 (tradename: sorbitan monooleate) and SPAN85 (trademark: sorbitan trioleate) manufactured by ICI. Further, aliphatic, alicyclic, or aromatic alcohols having 6 or more carbon atoms and at least a part of which can be dissolved in an inert solvent or polymer, for example, branched alcohols such as 2-ethylhexanol, lauryl alcohol, and the like Although higher alcohols can be used, the fatty acid ester compounds of the polyhydric alcohols are preferred from the viewpoint of the effect.

  The addition of the fatty acid ester compound or alcohol of the polyhydric alcohol is preferably performed after the primary denaturation reaction of the polymer is stopped, followed by stirring. In this case, the addition amount is preferably 0.2 to 10 mol, and particularly preferably 1 to 10 mol, per 1 mol of the hydrocarbyloxysilyl group provided to the polymer.

  Next, in the modification method (2), the hydrocarbyloxysilane compound represented by the following formula (IV) and / or a partial condensate thereof is further converted to a hydrocarbyloxysilane compound represented by the above formula (III) And / or a partial condensate thereof. Here, the partial condensate refers to a product in which a part (but not all) of the SiOR of the hydrocarbyloxysilane compound is SiOSi-bonded by condensation.

（式中、Ａ²は環状三級アミン、非環状三級アミン、ピリジン、スルフィド及びマルチスルフィドの中から選ばれる少なくとも一種の官能基を有する一価の基で；Ｒ⁸は単結合又は二価の不活性炭化水素基で；Ｒ⁹及びＲ¹⁰は、それぞれ独立に炭素数１〜２０の一価の脂肪族炭化水素基又は炭素数６〜１８の一価の芳香族炭化水素基で；ｍは０〜２の整数であり；ＯＲ¹⁰が複数ある場合、複数のＯＲ¹⁰は互いに同一でも異なっていてもよく；また分子中には活性プロトン及びオニウム塩は含まれない。）

(Wherein A ² is a monovalent group having at least one functional group selected from a cyclic tertiary amine, an acyclic tertiary amine, pyridine, sulfide and multisulfide; R ⁸ is a single bond or a divalent group. R ⁹ and R ¹⁰ 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; m It is an integer of 0 to 2; if oR ¹⁰ there are a plurality or different and a plurality of oR ¹⁰ on the same to each other; in addition the molecule does not include active proton and an onium salt).

  The hydrocarbyloxysilane compound represented by the formula (IV) and / or a partial condensate thereof were introduced into the active terminal because the direct reaction with the active terminal did not substantially occur and remained in the reaction system unreacted. It is consumed for condensation with the hydrocarbyloxysilane compound residue.

In the formula (IV), the acyclic tertiary amine of A ² includes an N, N- (disubstituted) aromatic amine such as N, N- (disubstituted) aniline, and the cyclic tertiary amine is And (thio) ether as part of the ring. Divalent inactive hydrocarbon group out of R ^8, the R ⁹ and R ¹⁰ are as described R ^5, R ⁶ and R ⁷ in each of the formulas (III). It is necessary that this molecule does not have active protons and onium salts.

  Examples of the hydrocarbyloxysilane compound represented by the formula (IV) include, for example, non-cyclic tertiary amine group-containing hydrocarbyloxysilane compounds such as 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-dimethylaminopropyl (triethoxy) silane Examples thereof include dibutylaminopropyl (triethoxy) silane, and among these, 3-diethylaminopropyl (triethoxy) silane and 3-dimethylaminopropyl (triethoxy) silane are 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-dodecamethyleneimino ) Propyl (triethoxy) silane, 3- (1-hexamethyleneimino) propyl (diethoxy) methylsilane, 3- (1- Xamethyleneimino) propyl (diethoxy) ethylsilane is exemplified, among which 3- (1-hexamethyleneimino) propyl (triethoxy) silane is particularly preferred.

  Further, other hydrocarbyloxysilane compounds include 2- (trimethoxysilylethyl) pyridine, 2- (triethoxysilylethyl) pyridine, 4-ethylpyridine and the like.

  These hydrocarbyloxysilane compounds may be used alone or in a combination of two or more. In addition, partial condensates of these hydrocarbyloxysilane compounds can also be used.

  In the modification method (2), the hydrocarbyloxysilane compound II condensed with the residue of the hydrocarbyloxysilane compound I introduced at the active terminal of the polymer may be a hydrocarbyl compound represented by the formula (III) Oxysilane compounds and partial condensates thereof, hydrocarbyloxysilane compounds represented by the formula (IV) and partial condensates thereof, and hydrocarbyloxysilane compounds represented by the following formula (V) and partial condensates thereof At least one selected may be used.

（式中、Ａ³はアルコール、チオール、第一級アミン又はそのオニウム塩、環状二級アミン又はそのオニウム塩、非環状二級アミン又はそのオニウム塩、環状三級アミンのオニウム塩、非環状三級アミンのオニウム塩、アリール又はベンジルＳｎ結合を有する基、スルフォニル、スルフィニル及びニトリルの中から選ばれる少なくとも一種の官能基を有する一価の基で；Ｒ¹¹は単結合又は二価の不活性炭化水素基で；Ｒ¹²及びＲ¹³は、それぞれ独立に炭素数１〜２０の一価の脂肪族炭化水素基又は炭素数６〜１８の一価の芳香族炭化水素基で；ｑは０〜２の整数であり；ＯＲ¹³が複数ある場合、複数のＯＲ¹³はたがいに同一でも異なっていてもよい。）

(Wherein, A ³ is an alcohol, a thiol, a primary amine or an onium salt thereof, a cyclic secondary amine or an onium salt thereof, an acyclic secondary amine or an onium salt thereof, an onium salt of a cyclic tertiary amine, an acyclic triamine An onium salt of a secondary amine, a group having an aryl or benzyl Sn bond, a monovalent group having at least one functional group selected from sulfonyl, sulfinyl and nitrile; and R ¹¹ is a single bond or a divalent inert carbon. R ¹² and R ¹³ 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; be an integer; if OR ¹³ there are a plurality, the plurality of OR ¹³ may be the same with or different from each other).

In the formula (V), the primary amine of A ³ includes an aromatic amine such as aniline, and the acyclic secondary amine is an N- (monosubstituted) aromatic amine such as N- (monosubstituted) aniline. Is included. Further, onium salts of acyclic tertiary amines include onium salts of N, N- (disubstituted) aromatic amines such as N, N- (disubstituted) aniline. Also. In the case of a cyclic secondary amine or a cyclic tertiary amine, a (thio) ether can be contained as a part of the ring. The divalent inert hydrocarbon group, R ¹² and R ¹³ of R ¹¹ are as described for R ⁵ , R ⁶ and R ⁷ in the formula (III), respectively.

  Examples of the hydrocarbyloxysilane compound represented by the formula (V) include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, hydroxymethyltrimethoxysilane, hydroxymethyltriethoxysilane, mercaptomethyltrimethoxysilane , Mercaptomethyltriethoxysilane, aminophenyltrimethoxysilane, aminophenyltriethoxysilane, 3- (N-methylamino) propyltrimethoxysilane, 3- (N-methylamino) propyltriethoxysilane, octadecyldimethyl (3- Trimethylsilylpropyl) ammonium chloride, octadecyldimethyl (3-triethylsilylpropyl) ammonium chloride, cyanomethyltrimethoxysilane, cyanomethyltriethoxysilane, sulfonylmethyltrichloride Examples include methoxysilane, sulfonylmethyltriethoxysilane, sulfinylmethyltrimethoxysilane, and sulfinylmethyltriethoxysilane.

  As the hydrocarbyloxysilane compound II, one type may be used alone, or two or more types may be used in combination.

  In the modification method (2), the polymer having an active terminal is reacted with a substantially stoichiometric amount of the hydrocarbyloxysilane compound I added to the reaction system, and substantially all of the terminals are reacted. A hydrocarbyloxysilyl group is introduced (primary modification), and the hydrocarbyloxysilyl group introduced above is reacted with a hydrocarbyloxyl group-containing compound, so that more than an equivalent of a hydrocarbyloxysilane compound residue is added to the active terminal. Is introduced.

  The condensation reaction between alkoxysilyl groups occurs between free (remaining or newly added) alkoxysilane and an alkoxysilyl group at a polymer terminal, and in some cases, occurs between alkoxysilyl groups at a polymer terminal. Preferably, the reaction between free alkoxysilanes is unnecessary. Therefore, when an alkoxysilane compound is newly added, it is preferable from the viewpoint of reaction efficiency that the hydrolyzability of the alkoxysilyl group does not exceed the hydrolyzability of the alkoxysilyl group at the polymer terminal. For example, a compound containing a trimethoxysilyl group having a large hydrolyzability is used for the alkoxysilane I, and an alkoxysilyl group (for example, a triethoxysilyl group) having a lower hydrolyzability is used for the newly added alkoxysilane II. Combinations using the compounds described above are preferred. Conversely, for example, making alkoxysilane I a triethoxysilyl group-containing compound and alkoxysilane II a trimethoxysilyl group-containing compound are within the scope of the present invention, but are not preferred from the viewpoint of reaction efficiency.

  The denaturation reaction (1) and (2) in the present invention may be either a solution reaction or a solid phase reaction, but a solution reaction (a solution containing an unreacted monomer used at the time of polymerization) is preferable. The type of the denaturation reaction is not particularly limited, and may be carried out using a batch reactor, or may be carried out continuously using a multistage continuous reactor or an apparatus such as an in-line mixer. In addition, it is important that the modification reaction be performed after the completion of the polymerization reaction and before performing desolvation treatment, water treatment, heat treatment, various operations necessary for polymer isolation, and the like. As the temperature of the modification reaction, the polymerization temperature of the conjugated diene polymer can be used as it is, and specifically, 20 to 100 ° C. is preferable. When the temperature is low, the viscosity of the polymer tends to increase, and when the temperature is high, the polymerization active terminal is easily deactivated, which is not preferable.

  In order to promote the secondary modification, it is preferable to use a condensation accelerator. As the condensation accelerator, a combination of a metal compound generally known as a curing catalyst for an alkoxy condensation-curable room temperature crosslinking (RTV) silicone and water can be used. For example, a combination of tin carboxylate and / or titanium alkoxide with water is preferred. There is no particular limitation on the method of introducing the condensation accelerator into the reaction system of water. A solution of an organic solvent compatible with water such as alcohol may be used, or water may be directly injected, dispersed, and dissolved in the hydrocarbon solution using various chemical engineering techniques. As such a condensation accelerator, a compound comprising water and at least one selected from the group consisting of metal compounds represented by the following (1) to (3) is preferable.

(1) A carboxylate salt of tin having an oxidation number of 2 and having 3 to 30 carbon atoms, which satisfies the following formula.
Sn (OCOR ¹⁴ ) ₂
(In the formula, R ¹⁴ is an organic group having 2 to 19 carbon atoms, and when there are a plurality of them, they may be the same or different.)
(2) A tin compound having an oxidation number of 4 and satisfying the following formula.
R ¹⁵ _r SnA ⁴ _t B ¹ _(4-tr)
[In the formula, r is an integer of 1 to 3; t is an integer of 1 or 2; t + r is an integer of 3 or 4. R ¹⁵ is an aliphatic hydrocarbon group having 1 to 30 carbon atoms; B ¹ is a hydroxyl group or a halogen. A ⁴ represents (i) a carboxyl group having 2 to 30 carbon atoms, (ii) an α, γ-dionyl group having 5 to 30 carbon atoms, (iii) a hydrocarbyloxy group having 3 to 30 carbon atoms, and (iv) A group selected from siloxy groups which are totally trisubstituted (may be the same or different) with a hydrocarbyl group having 1 to 20 and / or a hydrocarbyloxy group having 1 to 20 carbon atoms, and when there are a plurality of A ^4, They may be the same or different. ]
(3) A titanium compound having an oxidation number of 4 and satisfying the following formula.
A ⁵ _x TiB ² _(4-x)
(In the formula, x is an integer of 2 or 4. A ⁵ is (i) an alkoxy group having 3 to 30 carbon atoms, (ii) an alkyl group having 1 to 30 carbon atoms and / or an alkyl group having 1 to 20 carbon atoms. the sum trisubstituted siloxy group with an alkoxy group, .B ² may be the same or different if a ⁵ there are multiple, alpha of 5 to 30 carbon atoms, a γ- dionyl group.)

  Specific examples of the tin carboxylate include (1) a divalent tin dicarboxylate (particularly preferably a carboxylate having 8 to 20 carbon atoms) and (2) a tetravalent dihydrocarbyltin. [Including bis (hydrocarbyl dicarboxylic acid) salt], bis (α, γ-diketonate), alkoxy halide, monocarboxylate hydroxide, alkoxy (trihydrocarbylsiloxide), alkoxy (dihydrocarbylalkoxysiloxide) ), Bis (trihydrocarbylsiloxide), bis (dihydrocarbylalkoxysiloxide) and the like are preferred. The hydrocarbyl group directly bonded to tin preferably has 4 or more carbon atoms, and particularly preferably has 4 to 8 carbon atoms.

  Examples of the titanium compound include a tetraalkoxide of titanium having an oxidation number of 4, a dialkoxybis (α, γ-diketonate), and tetrakis (trihydrocarboxyoxysiloxide). Among these, a tetraalkoxide is preferable. .

  On the other hand, as the water, a form such as a simple substance or a solution of alcohol or the like, micelles dispersed in a hydrocarbon solvent, or the like is preferably used. Moisture potentially contained by compounds capable of releasing water in the system can also be used effectively.

  These two forming the condensation accelerator may be separately charged into the reaction system, or may be mixed immediately before use and charged as a mixture, but long-term storage of the mixture is not preferable because it causes decomposition of the metal compound. .

  The amount of the condensation promoter used is preferably such that the molar ratio of the metal of the metal compound and water effective for the reaction to the total amount of hydrocarbyloxysilyl groups present in the reaction system is 0.1 or more. Although the upper limit varies depending on the purpose and reaction conditions, it is preferable that about 0.5 to 3 effective water is present in a molar ratio to the total amount of hydrocarbyloxysilyl groups bonded to the polymer terminal before the condensation treatment. The mole ratio of the metal of the metal compound and water effective for the reaction varies depending on the required reaction conditions, but is preferably about 1 / 0.5 to 1/20.

  Furthermore, in the present invention, after the hydrocarbyloxysilane compound is reacted with the active terminal of the polymer, a condensation accelerator is added and reacted, and thereafter, the reaction can be further performed with the carboxylic acid ester compound of the polyhydric alcohol. .

  In the present invention, at the time of this modification reaction, if necessary, a known antioxidant or a short stop agent can be added in a step after the introduction of the hydrocarbyloxysilane compound residue into the active terminal of the polymer.

  After the modification treatment as described above, a conventionally known post-treatment such as desolvation is performed to obtain a desired modified polymer. Analysis of the polymer chain terminal modified group of the modified polymer can be performed by using liquid chromatography as a carrier such as high performance liquid chromatography (HPLC) or thin layer chromatography, or by using nuclear magnetic resonance spectroscopy (NMR). it can.

The Mooney viscosity ML _{1 + 4} (100 ° C.) of the above terminal-modified conjugated diene polymer is preferably from 10 to 150, and more preferably from 15 to 70. If the Mooney viscosity is low, rubber properties such as breaking properties tend to be low, and if it is high, workability is poor and it is difficult to knead with a compounding agent. When the terminal-modified conjugated diene-based polymer is used as a rubber component in a rubber composition in which an inorganic compound such as silica or carbon black is compounded as a filler, the interaction with the filler is enhanced and destroyed regardless of the type. The properties, abrasion resistance and low heat generation can be simultaneously improved, and good workability can be exhibited.

  The terminal-modified conjugated diene-based polymer which can be used as the rubber component of the rubber composition of the present invention includes a copolymer of 1,3-butadiene and a vinyl aromatic compound or a homopolymer of 1,3-butadiene. A modified conjugated diene polymer having at least one functional group selected from the group consisting of a substituted amino group represented by the above formula (I) and a cyclic amino group represented by the above formula (II) Is also preferred. Here, examples of the vinyl aromatic compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, and vinylnaphthalene, and among them, styrene is preferable. In the modified conjugated diene-based polymer, the binding amount of the vinyl aromatic compound in the polymer is preferably 20% by mass or less, and particularly preferably 0% by mass. When the bonding amount of the vinyl aromatic compound in the polymer is 0% by mass, the modified conjugated diene-based polymer is a homopolymer of 1,3-butadiene, that is, polybutadiene. In the modified conjugated diene polymer, the butadiene portion (1,3-butadiene unit) preferably has a vinyl bond content of 30% or less. The modified conjugated diene-based copolymer preferably has a glass transition temperature of -50 ° C or lower.

In the formula (I), R ¹ is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aralkyl group, and is a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, a 3-phenyl-1-propyl group. And an isobutyl group. Note that R ¹ may be the same or different.

In the formula (II), R ² is a divalent 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 mono- to octa-substituted alkylene group. 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. 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.

R ² can be derived from cyclic amines, which are not particularly limited, but include azacycloheptane (ie, hexamethyleneimine), 2- (2-ethylhexyl) pyrrolidine 3,3- (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-azacycloheptadec-9-ene, 3-isobutyl-1-azacyclododecane, 2-methyl-7-t-butyl-1-azacyclo Dodeca 5-nonyl-1-azacyclododecane, 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, 1-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] decane, and the like.

  As a method for introducing a substituted amino group of the formula (I) or a cyclic amino group of the formula (II) into a conjugated diene polymer, for example, as described in JP-A-2001-131227, a conjugated diene polymer There is also a method of bonding to an organic group having a 2-hydroxy-1,3-propylene group bonded to at least one nitrogen atom in a cyclic amino group, but a polymerization initiator composed of lithioamine or a lithioamine and an organic compound It is preferable to use a polymerization initiator consisting of a mixture with an alkali metal to modify the polymerization initiation terminal with the amino group.

That is, a solution of one or more anionic polymerizable monomers is formed in a hydrocarbon solvent, and a solution of the following general formula: (AM) Li (Q) _a
Wherein a is 0 or 0.5 to 3, Q is a solubilizing component selected from the group consisting of hydrocarbons, ethers, amines and mixtures thereof, and AM is )) Or a cyclic amino group represented by the formula (II)], or a mixture of the lithioamine and an organic alkali metal compound is used as a polymerization initiator to polymerize the above monomer. As a result, a modified conjugated diene polymer into which the substituted amino group of the formula (I) or the cyclic amino group of the formula (II) has been introduced can be obtained.

  The above (Q) is a solubilizing component, and may be a hydrocarbon, an ether, an amine or a mixture thereof. When the component (Q) is present, the lithioamine becomes soluble in a hydrocarbon solvent. Also, (Q) includes dienyl or vinyl aromatic polymers or copolymers having a degree of polymerization of from 3 to about 300 polymerized units. The polymers include polybutadiene, polystyrene, polyisoprene and copolymers thereof. Other examples of (Q) include polar ligands such as tetrahydrofuran (THF) and tetramethylethylenediamine (TMEDA).

  The above (AM) is a substituted amino group represented by the above formula (I) or a cyclic amino group represented by the above formula (II). A polymer having at least one group of at the end is synthesized.

When the soluble component (Q) is an ether or an amino compound, a solution of the functionalizing agent AM-H is prepared using an anhydrous aprotic solvent such as cyclohexane in the presence of (Q); Next, a polymerization initiator can be generated by adding a solution of the organolithium compound dissolved in the same or similar solvent to this solution. The organolithium compound has the following general formula:
R ¹⁶ Li
Wherein R ¹⁶ is an alkyl, cycloalkyl, alkenyl, aryl, and aralkyl group having 1 to about 20 carbon atoms, and a short group having up to 25 units obtained from diolefin and vinylaryl monomers. Selected from the group consisting of low molecular weight polymers having a chain length). Here, examples of the alkyl group include an n-butyl group, an s-butyl group, a methyl group, an ethyl group, and an isopropyl group.Examples of the cycloalkyl group include a cyclohexyl group and a menthyl group. Is an allyl group, a vinyl group or the like. Further, the aryl group and the aralkyl group include a phenyl group, a benzyl group, an oligo (styryl) group and the like, and the short-chain long polymers are formed by initiating oligomerization of a suitable monomer with organolithium. Oligo (butadienyl) s, oligo (isoprenyl) s, oligo (styryl) s and the like. As the organic lithium compound, n-butyllithium is preferable.

The organic alkali metal compound that can be used in the initiator system includes the following general formula:
R ¹⁷ M
R ¹⁸ OM
R ¹⁹ C (O) OM
R ²⁰ R ²¹ NM
R ²² SO ₃ M
Wherein R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² are each an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an alkenyl group, an aryl group or a phenyl group, and M is , Na, K, Rb or Cs]. Here, Na and K are particularly preferable as the metal component M. The initiator mixture consisting of lithioamine and the organic alkali metal compound preferably contains from about 0.02 to about 0.5 equivalents of the organic alkali metal compound per equivalent of lithium in the lithioamine initiator.

  A chelating agent can be added to the above-mentioned initiator or a mixture thereof so as not to make the polymerization uneven. Useful chelating agents include tetramethylethylenediamine (TMEDA), oxolanyl cyclic acetals, cyclic oligomeric oxolanyl alkanes, etc. Among them, cyclic oligomeric oxolanyl alkanes are particularly preferred.

  As the polymerization solvent, various hexanes, heptanes, octanes, and mixtures thereof are used.

The modified conjugated diene-based polymer having a substituted amino group of the formula (I) or a cyclic amino group of the formula (II) further has the following general formula:
R ²³ _b SnX _c
(Wherein, R ²³ is selected from the group consisting of 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; X is chlorine or bromine, b is 0 to 3, c is 1 to 4, where b + c = 4), and at least one tin-carbon bond derived from a coupling agent represented by the formula: It is preferred to have. In this case, the butadiene-based polymer can further improve the low heat build-up of the rubber composition. As the R ^23, a methyl group, an ethyl group, n- butyl group, neophyl group, cyclohexyl group, n- octyl group, a 2-ethylhexyl group. Among the coupling agents include tin _{^{tetrachloride, R 23 SnCl 3, R 23}} 2 SnCl 2, R 23 3 SnCl , and the like are preferable, and tin tetrachloride is particularly preferred.

  Further, other modifiers can be used for the modified conjugated diene-based polymer. Preferred other modifiers include carbodiimides, N-methylpyrrolidinone, cyclic amides, cyclic ureas, isocyanates, Schiff bases, 4,4′-bis (diethylamino) benzophenone, and the like.

  The modified conjugated diene-based polymer is a polymer having at least one kind of the amino group (AM) at the terminal, where AM can be derived from a reaction product of an amine and an organolithium compound.

  Further, the modified conjugated diene polymer having AM at the terminal is preferably a polyfunctional polymer having a tin-carbon bond in the molecular chain or at the terminal, and the tin-carbon bond is, for example, terminated. It can be derived from a modifier consisting of an agent, a coupling agent and a linking agent. After adding these modifiers to the reaction vessel, the vessel is agitated for about 1 to about 1000 minutes to form a tin-carbon bond in the polymer. The butadiene-based polymer having a tin-carbon bond has a large affinity for carbon black as a reinforcing filler, and thus improves the dispersibility of carbon black. As a result, the low heat build-up of the rubber composition is reduced. Greatly improved.

  The content of the terminal-modified conjugated diene polymer in the rubber component of the rubber composition of the present invention is preferably 30% by mass or more, more preferably 35% by mass or more, and particularly preferably 40 to 100% by mass. The terminal-modified conjugated diene-based polymer may be used alone or in combination of two or more.

  Foaming agents used in the rubber composition of the present invention include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), dinitrosopentastyrenetetramine and benzenesulfonylhydrazide derivatives, P, P'-oxybisbenzenesulfonylhydrazide (OBSH), ammonium bicarbonate that generates carbon dioxide, sodium bicarbonate, ammonium carbonate, a nitrososulfonylazo compound that generates nitrogen, N, N′-dimethyl-N, N′-dinitrosophtalamide, toluenesulfonylhydrazide, P-toluenesulfonyl semicarbazide, P, P'-oxybisbenzenesulfonyl semicarbazide and the like can be mentioned. Among these foaming agents, azodicarbonamide (ADCA) and dinitrosopentamethylenetetramine (DPT) are preferred from the viewpoint of processability, and azodicarbonamide (ADCA) is particularly preferred. These foaming agents may be used alone or in combination of two or more.

  The form of the foaming agent is not particularly limited, and can be appropriately selected from particles, liquids, and the like according to the purpose. The form of the foaming agent can be observed using, for example, a microscope. The average particle size of the particulate foaming agent can be measured, for example, using a Coulter counter or the like.

  Further, it is preferable to use urea, zinc stearate, zinc benzenesulfinate, zinc white, or the like as a foaming aid in the foaming agent. These may be used alone or in combination of two or more. By using a foaming aid together, the foaming reaction can be promoted to increase the degree of completion of the reaction, and unnecessary deterioration with time can be suppressed.

  The rubber composition of the present invention is a short fiber made of a thermoplastic resin, and in the matrix of the rubber composition until the temperature of the rubber composition reaches the maximum vulcanization temperature during vulcanization. It preferably contains short fibers characterized by melting or softening. Here, the compounding amount of the short fiber is 0.2 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component. Here, the rubber matrix includes a component excluding short fibers in the rubber composition, and specifically includes at least a rubber component and a foaming agent, and is appropriately selected according to the purpose as another configuration. It consists of fillers, vulcanizing chemicals, additives and others. Further, the maximum vulcanization temperature means the maximum temperature reached by the rubber composition during vulcanization. For example, in the case of mold vulcanization, it means the maximum temperature at which the rubber composition reaches between the time when the rubber composition enters the mold and the time when the rubber composition leaves the mold and is cooled. The maximum vulcanization temperature can be measured, for example, by embedding a thermocouple in the rubber composition.

  The material of the short fiber is not particularly limited as long as it is a thermoplastic resin having the above-mentioned thermal characteristics, and can be appropriately selected depending on the purpose. Preferable examples of the short fibers having the above-mentioned thermal properties include short fibers made of a crystalline polymer having a melting point lower than the maximum vulcanization temperature. Taking the short fibers made of the crystalline polymer as an example, as the difference between the melting point of the short fibers and the maximum vulcanization temperature of the rubber composition increases, the vulcanization of the rubber composition quickly proceeds. The short fibers melt. On the other hand, when the melting point of the short fiber is too close to the maximum vulcanization temperature of the rubber composition, the short fiber does not melt quickly at the beginning of vulcanization, but melts at the end of vulcanization. At the end of vulcanization, the air present in the short fibers is diffused and dispersed or taken into the vulcanized rubber matrix, and a sufficient amount of air is not retained in the molten short fibers. . On the other hand, if the melting point of the short fibers is too low, the short fibers are melted by heat during kneading of the rubber composition, poor dispersion due to fusion of the short fibers at the kneading stage, and short fibers at the kneading stage. However, it is not preferable because there are disadvantages such as that the short fibers are divided into a plurality of pieces, and the short fibers dissolve in the rubber composition and are microscopically dispersed.

  The upper limit of the melting point (or softening point) of the short fibers is not particularly limited, but is preferably selected in consideration of the above points, and is generally higher than the maximum vulcanization temperature of the rubber composition. , Preferably at least 10 ° C, more preferably at least 20 ° C. The industrial vulcanization temperature of the rubber composition is generally up to about 190 ° C., for example, when the maximum vulcanization temperature is set at 190 ° C., the melting point of the short fibers Is usually selected within the range of 190 ° C. or lower, preferably 180 ° C. or lower, more preferably 170 ° C. or lower. On the other hand, considering the kneading of the rubber composition, the melting point (or softening point) of the short fibers is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, with respect to the maximum temperature at the time of kneading. The above is particularly preferred. Assuming that the maximum temperature during kneading of the rubber composition is, for example, 95 ° C., the melting point of the short fibers is preferably 100 ° C. or higher, more preferably 105 ° C. or higher, and particularly preferably 115 ° C. or higher. The melting point of the short fibers can be measured using a melting point measuring device known per se, and for example, the melting peak temperature measured using a DSC measuring device can be used as the melting point.

  The short fibers may be formed from the above-described crystalline polymer, may be formed from an amorphous polymer, or may be formed from a crystalline polymer and an amorphous polymer. In the present invention, in the present invention, it is preferably formed from an organic material containing a crystalline polymer in that the viscosity change occurs rapidly at a certain temperature due to a phase transition, and the viscosity is easily controlled. More preferably, it is formed only from a conductive polymer.

  Examples of the crystalline polymer include polyethylene (PE), polypropylene (PP), polybutylene, polybutylene succinate, polyethylene succinate, syndiotactic-1,2-polybutadiene (SPB), polyvinyl alcohol (PVA), Polymers of a single composition such as polyvinyl chloride (PVC), copolymers whose melting point is controlled in an appropriate range by copolymerization, blending, and the like can be used, and those obtained by further adding additives can also be used. These may be used alone or in combination of two or more. Among these crystalline polymers, polyolefins and polyolefin copolymers are preferred, and polyethylene (PE) and polypropylene (PP) are more preferred in that they are easily available for general use.Polyethylene (PE) has a low melting point and is easy to handle. ) Are particularly preferred.

  Examples of the non-crystalline polymer include polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene (PS), polyacrylonitrile, copolymers thereof, and blends thereof. And the like. These may be used alone or in combination of two or more. Further, the crystalline polymer and the non-crystalline polymer may be used in combination.

  The molecular weight of the material of the staple fiber varies depending on the chemical composition of the material, the state of branching of the molecular chain, etc., and cannot be unconditionally defined.In general, even if the staple fiber is formed of the same material, its molecular weight is The higher the is, the higher the melting point or softening point. In the present invention, the molecular weight of the raw material of the short fibers is selected within a range such that the melting point or softening point of the short fibers does not become higher than the maximum vulcanization temperature of the rubber composition. In addition, known additives may be added to the short fibers as needed as long as the object of the present invention is not impaired.

  The denier of the short fiber is not particularly limited and can be appropriately selected depending on the purpose.From the viewpoint of improving the performance on ice and snow, 1 to 1000 denier is preferable, and 2 to 800 denier is more preferable. .

  The average diameter (D) of the short fibers is not particularly limited and may be appropriately selected depending on the intended purpose.In a vulcanized rubber obtained by vulcanizing a rubber composition containing the short fibers, In order to efficiently form long bubbles that can function as micro drains described below, the length is preferably 0.03 to 0.3 mm, more preferably 0.06 to 0.25 mm. When the average diameter (D) is less than 0.03 mm, it becomes difficult to form a long cylindrical foam groove, and it is not preferable in that many yarn breaks occur during the production of the short fibers, and when it exceeds 0.3 mm. In addition, the average diameter (diameter) of the short fibers increases, and the number of cylindrical foam grooves decreases with the same blending amount, and the drainage efficiency tends to deteriorate.

  The average length (L) of the short fibers is not particularly limited and may be appropriately selected depending on the purpose.From the viewpoint of improving performance on ice and snow, the average length is preferably 1 to 10 mm, and 2 to 8 mm. More preferred. If the average length (L) is less than 1 mm, mechanical cutting becomes difficult, and the productivity of the short fibers may deteriorate.If the average length (L) exceeds 10 mm, poor dispersion at the time of kneading the rubber composition. In addition, misalignment during extrusion may occur. The average length (L) and the average diameter (D) of the short fibers can be measured by, for example, an optical microscope.

  When the rubber composition of the present invention contains the above-described short fibers, the short fibers are melted or softened during vulcanization, while the gas generated during vulcanization in the rubber matrix has undergone a vulcanization reaction. It stays inside the melted or softened thermoplastic resin compared to the rubber matrix. As a result, in the vulcanized rubber obtained by vulcanizing the rubber composition, air bubbles are present at the place where the short fibers existed. The bubbles (wall surfaces of the bubbles) are covered with the thermoplastic resin in the short fibers to form a capsule. These bubbles are present independently in the vulcanized rubber. When the material of the thermoplastic resin in the short fibers is polyethylene, polypropylene, or the like, the vulcanized rubber matrix and the resin are firmly bonded.

  When the rubber composition of the present invention contains the above-mentioned short fibers, long cells are present in the rubber matrix after vulcanization. When the short fibers are oriented in a certain direction in the rubber composition, as shown in FIG. 1, the long bubbles 1 exist in a state of being oriented in a certain direction. In addition, the orientation direction of the short fibers can be aligned in a certain direction in the step of extruding the rubber composition. The orientation state of the rubber composition after vulcanization can be confirmed by slicing the rubber composition parallel to the extrusion direction and observing the cross section with a microscope. Here, the long bubbles 1 are surrounded by a protective layer 3 formed by bonding a resin in a molten short fiber to a vulcanized rubber matrix 2. Further, gas generated from the foaming agent is taken into the protective layer 3.

  When such a rubber composition is used for a tread of a tire, when the tread is worn, as shown in FIG. 2, the concave portion 4 formed by exposing the long bubbles 1 to the surface performs efficient drainage. Functions as a drain.

  Further, in the tire using such a rubber composition for a tread, since the surface of the concave portion 4 is covered with the protective layer 3, the tire also has a water channel shape retention property, a water channel edge wear property, a water channel retention property at the time of load input, and the like. Excellent. The thickness of the protective layer 3 is preferably 0.5 to 50 μm. When the protective layer 3 is made of polyethylene, polypropylene, or the like, the protective layer 3 is firmly adhered to the vulcanized rubber matrix 2. The fiber may contain a component capable of improving the adhesion to the vulcanized rubber matrix 2.

  The ratio (L '/ D') between the average length (L ') and the average diameter (D') per one of the long bubbles 1 is preferably 3 or more, more preferably 5 or more. The upper limit of L ′ / D ′ is not particularly limited, but is selected to be about 100. When L ′ / D ′ is less than 3, the groove formed by the elongated bubbles 1 exposed on the surface of the worn vulcanized rubber composition cannot be lengthened, and the volume cannot be increased. When the rubber composition is used for a tread or the like of a tire, it is not preferable because the water removal performance of the tire cannot be sufficiently improved.

  The average diameter (D ') of the long bubbles 1 (i.e., the inner diameter of the protective layer 3) is preferably from 20 to 500 m. When the average diameter (D ′) is less than 20 μm, even if the rubber composition is used for a tread of a tire, the water drainage performance of the tire is not improved, and when it exceeds 500 μm, the rubber composition is vulcanized. Since the cut resistance of the vulcanized rubber is deteriorated and the chipping of the block is liable to occur, and also the wear resistance on the dry road surface of the tire is deteriorated even when the rubber composition is used for a tread or the like of the tire. Not preferred.

  In the present invention, as described above, the average foaming ratio (Vs) is 5 to 30%, and the elongated cells 1 may occupy 30% by volume or more of all the cells in the rubber composition after vulcanization. More preferably, the long cells 1 occupy 80% by volume or more of all the cells in the rubber composition after vulcanization.

  In the vulcanized rubber obtained by vulcanizing the rubber composition containing the short fibers, the capsule-shaped elongated bubbles having a substantially circular cross section perpendicular to the longitudinal direction (A direction) are not collapsed. It is formed efficiently. Since the capsule-shaped long bubbles can function as micro drains, the vulcanized rubber is extremely excellent in the performance on ice and snow. Here, the uneven distribution of the foaming agent in the short fibers is prevented to prevent uneven foaming, and the capsule-shaped long bubbles having a substantially circular cross section perpendicular to the longitudinal direction are crushed in a state where they are not collapsed. From the viewpoint of efficient formation, the foaming agent is preferably in the form of fine particles, and the average particle diameter of the particulate foaming agent is, for example, preferably 0.1 to 20 μm, more preferably 0.5 to 10 μm. .

  In the rubber composition of the present invention, an inorganic filler such as carbon black or silica, a silane coupling agent, a softening agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, as long as the object of the present invention is not impaired. Various additives commonly used in the rubber industry, such as zinc white, stearic acid, and an antiozonant, can be appropriately compounded.

  The studless tire of the present invention is characterized in that the above rubber composition is used for a tread rubber. Therefore, the studless tire is excellent in performance on ice and snow and durability against heat generation. The studless tire is particularly preferable as a heavy-load studless tire because both performance on ice and snow and durability against heat generation are compatible. When a rubber composition containing short fibers is applied to a tread of a tire, the orientation direction of the long bubbles is preferably substantially the tire circumferential direction. Here, the orientation directions of the long bubbles need not be all in the tire circumferential direction, and may be partially in directions other than the tire circumferential direction.

  A studless tire in which a rubber composition containing short fibers is applied to a tread can be manufactured, for example, as follows. That is, first, a rubber composition containing short fibers is prepared. In the rubber composition, the short fibers are oriented in a certain direction in the extrusion step. The rubber composition is stuck on a base portion of an uncured case tire previously stuck on a crown portion of a green tire case. At this time, the orientation direction of the short fibers is made to coincide with the tire circumferential direction. Then, by performing vulcanization molding with a predetermined mold under a predetermined temperature and a predetermined pressure, a studless tire in which a rubber composition containing short fibers is applied to a tread is obtained. At this time, when the unvulcanized tread is heated in the mold, the foaming agent in the rubber matrix foams and gas is generated. On the other hand, when the thermoplastic resin of the short fibers is melted or softened, most of the gas generated in the rubber matrix remains inside the short fibers.

  When running a studless tire in which the rubber composition containing short fibers manufactured as described above is applied to a tread, the surface of the tread of the tire is worn due to friction between the tire and a road surface, and the long bubbles 1 The groove-shaped recess 4 is exposed on the tread ground surface. On the other hand, when the tire is driven on an icy and snowy road surface, a water film is formed between the tire and the icy and snowy road surface due to the contact pressure and frictional heat between the tire and the contact surface thereof. This water film is quickly removed and removed by the myriad recesses 4 exposed on the tread ground contact surface. Therefore, the tire is less likely to slip on the icy and snowy road surface.

  Further, in a studless tire in which a rubber composition containing short fibers is applied to a tread, a groove-shaped concave portion 4 substantially oriented in the circumferential direction of the tire functions as a drain groove for efficient drainage. Since the protective layer 3 having excellent peeling resistance is formed on the surface (periphery) of the concave portion 4, the concave portion 4 is hardly crushed even under a high load, and has high drainage groove shape retention and water rejection performance. According to No. 4, the drainage removal performance in the rotation direction rear of the tire is improved, so that the tire is particularly excellent in the braking performance on ice and snow. Further, in the tire, the μ on the snow and snow in the horizontal direction (coefficient of friction) is improved due to the scratching effect of the protective layer 3, and the handling on the snow and snow is improved.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

  Rubber compositions having the compounding formulations shown in Table 1 were prepared, and the expansion ratio, dynamic elastic modulus (E '), and tan δ were measured. The dynamic elastic modulus and tan δ were measured using a spectrometer at a strain of 1% and a frequency of 50 Hz. The rubber composition was applied to a tread to produce a prototype studless tire for heavy load of size 11R22.5, and the prototype tire was mounted on a truck, and the performance on ice and the tire temperature after running were measured by the following methods. did. Table 1 shows the results.

(1) Performance on Ice On a flat road on ice, the lap time was measured until the vehicle accelerated from a stationary state and proceeded 100 m. The larger the index value is, the shorter the arrival time is, and the more excellent the acceleration on ice is, and if the index value is 95 or more, the performance on ice is sufficient.

(2) Tire temperature after running The temperature of the tread of the tire was measured after running 50 rounds on a 100 m radius road on an asphalt road surface, and the temperature difference was shown based on Example 1. If the difference from Example 1 is + 2 ° C. or less, the heat generation is sufficiently low.

* 1 Ube Industries, BR150L.
* 2 Modified polybutadiene rubber synthesized by the following method-1.
* 3 Modified polybutadiene rubber synthesized by the following method-2.
* 4 SBR1500 # made by JSR.
* 5 N134.
* 6 Made of Nippon Silica, Nip Seal AQ.
* 7 Polyethylene material, made by Tyre, melting point = 125 ° C, fiber diameter = 3.6d, average diameter (D) = 0.023mm, average length (L) = 2mm.
* 8 Azodicarbonamide, manufactured by Otsuka Chemical.
* 9 Urea, manufactured by Otsuka Chemical.
* 10 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine.
* 11 N-cyclohexyl-2-benzothiazolesulfenamide.

<Method for producing modified polybutadiene rubber-1 (modified BR-1)>
283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine were each injected as a cyclohexane solution into a dried, nitrogen-substituted pressure-resistant glass container having an internal volume of about 900 mL. Then, 0.57 mmol of n-butyllithium (BuLi) was added thereto, and polymerization was carried out in a 50 ° C warm water bath equipped with a stirrer for 4.5 hours. The polymerization addition rate was almost 100%. To this polymerization system, 0.100 mmol of tin tetrachloride was added as a cyclohexane solution, followed by stirring at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of a 5% solution of 2,6-di-t-butylparacresol (BHT) in isopropanol was added to stop the reaction, followed by drying according to a conventional method to obtain a modified polybutadiene rubber (modified BR). .

The vinyl bond (1,2-bond) amount of the resulting modified BR was determined from the integration ratio in ¹ H-NMR [manufactured by JEOL Ltd., Alpha 400 MHz NMR apparatus, in CDCl ₃ ] spectrum. The amount was 14%. When the coupling efficiency of the obtained modified BR was calculated using the area ratio of the peak on the high molecular weight side in the data obtained by gel permeation chromatography (GPC), the coupling efficiency was 65%. Was. Further, the glass transition temperature was -95 ° C.

<Method for producing modified polybutadiene rubber-2 (modified BR-2)>
Production of WO 03/046020 According to the method described in Example 5, modified polybutadiene rubber-2 was produced.

(1) Preparation of catalyst In a dried / nitrogen-substituted glass bottle having a rubber stoppered volume of 100 mL, 7.11 g of a cyclohexane solution of butadiene (15.2% by weight) and a cyclohexane solution of neodymium neodecanoate (0.56%) were prepared in the following order. M) 0.59 mL, 10.32 mL of a toluene solution (3.23 M as aluminum concentration) of methylaluminoxane MAO (PMAO manufactured by Tosoh Akzo), and 7.77 mL of a hexane solution (0.90 M) of diisobutylaluminum hydride (Kanto Chemical) were added. After aging for 2 minutes, 1.45 mL of a hexane solution (0.95 M) of chlorinated diethylaluminum (manufactured by Kanto Chemical) was added, and the mixture was aged at room temperature for 15 minutes with occasional stirring. The concentration of neodymium in the catalyst solution thus obtained was 0.011 M (mol / liter).

(2) Production of Polymer Intermediate A glass bottle with a rubber stopper having a capacity of about 900 mL was dried and purged with nitrogen, and a dried and purified cyclohexane solution of 1,3-butadiene and dried cyclohexane were added thereto to add 1,3-butadiene. 400 g of a 12.5 wt% cyclohexane solution was charged. Next, 2.28 mL (0.025 mmol in terms of neodymium) of the catalyst solution prepared above was charged, and polymerization was performed in a 50 ° C warm water bath for 1.0 hour.

(3) Primary denaturation treatment As a primary denaturant, 23.5 molar equivalents (compared to neodymium) of GPMOS were introduced as a hexane solution (1.0 M) of 3-glycidoxypropyltrimethoxysilane (GPMOS; epoxy), The first denaturation reaction was performed by treating at 50 ° C. for 60 minutes.

(4) Treatment after Secondary Modification Subsequently, 1.76 mL (equivalent to 70.5 eq / Nd) of cyclohexane solution (1.01 M) of bis (2-ethylhexanoate) tin (BEHAS) was used as a condensation accelerator. 32 ul of ion-exchanged water (corresponding to 70.5 eq / Nd) was charged, and the mixture was treated in a 50 ° C hot water bath for 1.0 hour. Thereafter, 2 mL of a 5% solution of an antioxidant 2,2'-methylene-bis (4-ethyl-6-t-butylphenol) (NS-5) in isopropanol was added to the polymerization system to terminate the reaction. Reprecipitation was performed in isopropanol containing NS-5, and a modified BR-2 was obtained by drum drying. The Mooney viscosity ML _{1 + 4} (100 ° C.) of the resulting modified BR was 93 when measured at 100 ° C. using an RLM-01 tester manufactured by Toyo Seiki Seisaku-sho, Ltd.

  Since the tires of Examples 1 to 6 were obtained by applying the rubber composition having physical properties defined in the present invention to the tread, the tires had excellent performance on ice and the tire temperature after running was sufficiently low. On the other hand, the tire of Comparative Example 1 had insufficient performance on ice because the elasticity of the tread at a low temperature (0 ° C.) was too high. In addition, the tire of Comparative Example 2 had an excessively low elastic modulus at a high temperature (60 ° C.), so that the tire temperature after running was high, which was not preferable from the viewpoint of heat generation durability of the tire. In the tire of Comparative Example 3, since the tan δ was high, the heat generation of the rubber composition itself was high, and the tire temperature after running was high. In the tire of Comparative Example 4, since the foaming rate of the rubber composition used for the tread was too high, the elastic modulus at high temperatures was low, and as a result, the tire temperature after running was high.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic explanatory drawing after vulcanization of the rubber composition containing a short fiber. FIG. 3 is a schematic cross-sectional explanatory view of a rubber composition containing short fibers after progress of wear.

Explanation of reference numerals

Reference Signs List 1 long bubble 2 rubber matrix 3 protective layer 4 concave portion L 'average length of long bubble D' average diameter of long bubble

Claims (21)

  The rubber component is compounded with a foaming agent, the foaming rate after vulcanization is 5-30%, the dynamic elastic modulus at 0 ° C is 30MPa or less and the dynamic elastic modulus at 60 ° C is 7MPa or more. A rubber composition, characterized in that:   The rubber composition according to claim 1, wherein tan δ at 60 ° C is 0.25 or less.   The rubber composition contains short fibers made of a thermoplastic resin, and the short fibers are melted or vulcanized in a matrix of the rubber composition before the temperature of the rubber composition reaches the maximum vulcanization temperature during vulcanization. The rubber composition according to claim 1, wherein the rubber composition softens.   The rubber composition according to claim 3, wherein the short fibers have a diameter of 0.03 to 0.3 mm and a length of 1 to 10 mm.   The rubber composition according to claim 3 or 4, wherein the short fibers are made of a crystalline polymer and have a melting point of 100 to 190 ° C.   The rubber composition according to claim 3 or 4, wherein the short fibers are made of an amorphous polymer and have a softening point of 100 to 190 ° C.   The rubber composition according to any one of claims 3 to 6, wherein at least most of the bubbles generated during vulcanization are elongated after vulcanization and oriented in a certain direction.   The rubber composition according to claim 1, wherein the rubber component contains a terminal-modified conjugated diene polymer.   The terminal-modified conjugated diene-based polymer is obtained by polymerizing a conjugated diene-based monomer alone or together with another monomer, and has a cis-1,4-bond content of 75 mol% in the conjugated diene portion of the main chain. The rubber composition according to claim 8, wherein the active terminal of the conjugated diene-based polymer having an active terminal is modified with a modifying agent.   The terminal-modified conjugated diene-based polymer is obtained by polymerizing a conjugated diene-based monomer alone or together with another monomer, and has a cis-1,4-bond content of 75 mol% in the conjugated diene portion of the main chain. Fatty acid ester of a polyhydric alcohol containing a saccharide having 4 or more carbon atoms or a modified saccharide after the first modification in which the active terminal of the conjugated diene polymer having an active terminal is reacted with a hydrocarbyloxysilane compound as described above. And a compound having at least one hydroxyl group and a hydrocarbyloxysilane compound, and produced by performing a secondary modification by reacting at least one compound selected from the group consisting of hydrocarbyloxysilane compounds. Or the rubber composition according to 9. In the second modification, a condensation accelerator is used, and the condensation accelerator comprises at least one selected from the group consisting of metal compounds represented by the following (1) to (3) and water:
(1) Tin carboxylate having 3 to 30 carbon atoms and having an oxidation number of 2 and satisfying the following formula: Sn (OCOR ¹⁴ ) ₂
(In the formula, R ¹⁴ is an organic group having 2 to 19 carbon atoms, and when there are a plurality of them, they may be the same or different.)
(2) Tin compounds having an oxidation number of 4 and satisfying the following formula: R ¹⁵ _r SnA ⁴ _t B ¹ _(4-tr)
[In the formula, r is an integer of 1 to 3; t is an integer of 1 or 2; t + r is an integer of 3 or 4. R ¹⁵ is an aliphatic hydrocarbon group having 1 to 30 carbon atoms; B ¹ is a hydroxyl group or a halogen. A ⁴ represents (i) a carboxyl group having 2 to 30 carbon atoms, (ii) an α, γ-dionyl group having 5 to 30 carbon atoms, (iii) a hydrocarbyloxy group having 3 to 30 carbon atoms, and (iv) A group selected from siloxy groups which are totally trisubstituted (may be the same or different) with a hydrocarbyl group having 1 to 20 and / or a hydrocarbyloxy group having 1 to 20 carbon atoms, and when there are a plurality of A ^4, They may be the same or different. ]
(3) A titanium compound having an oxidation number of 4 and satisfying the following formula: A ⁵ _x TiB ² _(4-x)
(In the formula, x is an integer of 2 or 4. A ⁵ is (i) an alkoxy group having 3 to 30 carbon atoms, (ii) an alkyl group having 1 to 30 carbon atoms and / or an alkyl group having 1 to 20 carbon atoms. the sum trisubstituted siloxy group with an alkoxy group, .B ² may be the same or different if a ⁵ there are multiple, alpha of 5 to 30 carbon atoms, a γ- dionyl group.)
The polymerization catalyst used for the polymerization of the conjugated diene polymer is a combination of at least one compound selected from each of the following components (A), (B), and (C):
Component (A): a rare earth compound selected from the following (A1) to (A4), which may be used directly as an inert organic solvent solution or supported on an inert solid.
(A1) A rare earth compound having an oxidation number of 3, which is a carboxyl group having 2 to 30 carbon atoms, an alkoxy group having 2 to 30 carbon atoms, an aryloxy group having 6 to 30 carbon atoms, and an α, γ-diketonyl having 5 to 30 carbon atoms. Having a total of three ligands selected from the groups, or a complex compound of this with a Lewis base compound
(A2) Complex compound of rare earth trihalide and Lewis base
(A3) An organic rare earth compound having an oxidation number of 3, wherein at least one (substituted) allyl group is directly bonded to a rare earth atom
(A4) An organic rare earth compound having an oxidation number of 2 or 3 in which at least one (substituted) cyclopentadienyl group is directly bonded to a rare earth atom, or an ion comprising this compound and a trialkylaluminum or a non-coordinating anion and a counter cation Reaction product (B) component with a reactive compound: at least one type of organoaluminum compound selected from the following ones, and a plurality of them can be used simultaneously
(B1) R ³ ₃ trihydrocarbyl aluminum compound represented by Al (where, R ³ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other)
(B2) R ⁴ ₂ AlH or hydrocarbyl aluminum hydride represented by R ⁴ AlH ₂ (where, R ⁴ is a hydrocarbon group having 1 to 30 carbon atoms, may be the same or different from each other)
(B3) a hydrocarbylaluminoxane compound having a hydrocarbon group having 1 to 30 carbon atoms (C) component: a compound selected from the following, wherein (A) contains a halogen or a non-coordinating anion, and ( Not necessary when B) contains aluminoxane
(C1) Group II, III, IV inorganic or organic compounds having at least one hydrolyzable halogen or complex compounds thereof with Lewis bases
(C2) an organic halide having a structure selected from at least one tertiary alkyl halide, benzyl halide, and allyl halide
(C3) a zinc halide or a complex compound thereof with a Lewis base
(C4) an ionic compound comprising a non-coordinating anion and a counter cation, wherein the rare earth element is at least one selected from the group consisting of lanthanum, neodymium, praseodymium, samarium, and gadolinium,
The rubber composition according to claim 10, wherein the conjugated diene-based polymer is at least one selected from the group consisting of polybutadiene, polyisoprene, and a copolymer of butadiene and another conjugated diene. The terminal-modified conjugated diene-based polymer is a copolymer of butadiene and a vinyl aromatic compound or a homopolymer of butadiene, and has the following formula (I):

(Wherein R ¹ is independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aralkyl group), and the following formula (II):

(Wherein, R ² represents an alkylene group having 3 to 16 methylene groups, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group). The rubber composition according to claim 8, further comprising at least one functional group.   The rubber composition according to claim 12, wherein the terminal-modified conjugated diene-based polymer has a butadiene portion having a vinyl bond amount of 30% or less.   The rubber composition according to claim 12, wherein the terminal modified conjugated diene-based polymer has a binding amount of the vinyl aromatic compound of 20% by mass or less.   The rubber composition according to claim 12, wherein the terminal-modified conjugated diene-based polymer is a styrene-butadiene copolymer or polybutadiene.   The rubber composition according to claim 12, wherein the terminal-modified conjugated diene-based polymer has a glass transition temperature (Tg) of -50 ° C or lower. R ¹ in the formula (I) is a rubber according to claim 12, characterized in that a methyl group, an ethyl group, butyl group, octyl group, a cyclohexyl group, 3-phenyl-1-propyl or isobutyl Composition. 13. The method according to claim 12, wherein R ^{2 in the} formula (II) is a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group or a hexadecamethylene group. Rubber composition.   A studless tire using the rubber composition according to any one of claims 1 to 18 for a tread rubber.   A studless tire using the rubber composition according to claim 7 as a tread rubber, wherein the orientation direction of the elongated bubbles is substantially the tire circumferential direction.   21. The studless tire according to claim 19, wherein the studless tire is a heavy load studless tire.

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