JP6101130B2 - Rubber composition and tire using the same - Google Patents

Description

  The present invention relates to a rubber composition for a tire tread and a pneumatic tire using the rubber composition, and more specifically, a rubber composition excellent in low rolling resistance, scorch stability, and processability, and using the rubber composition It relates to a pneumatic tire.

In recent years, there has been an increasing demand for fuel efficiency reduction of automobiles in connection with the global movement of regulation of carbon dioxide emissions due to increasing interest in environmental problems. In order to meet such demands, tires are required to reduce rolling resistance. As a technique for reducing the rolling resistance of the tire, a technique of applying a low heat-generating rubber composition to the tire can be mentioned.
As a method for obtaining a rubber composition having low exothermicity, in the case of a synthetic diene rubber, a method of using a polymer having enhanced affinity for carbon black and silica as the rubber composition (see, for example, Patent Document 1) ). In the case of natural rubber, a method of blending highly reactive carbon black with a modified natural rubber obtained by modifying natural rubber (for example, see Patent Document 2).
According to Patent Documents 1 and 2, by increasing the affinity between a filler such as carbon black and a rubber component, the exothermic property of the rubber composition can be lowered, thereby obtaining a tire having a low hysteresis loss. be able to.
However, as the fuel efficiency of automobiles further advances, further improvements in tires with low heat generation have been desired.

JP 2003-514079 A International Publication No. 2007/066669

  An object of the present invention is to develop a rubber composition having a low heat build-up and a tire using the same by further promoting the reaction between the silane coupling agent and the polymer without adversely affecting the stability and processability of the scorch. It is what.

  As a result of intensive research in order to solve the above problems, the present inventor has made use of a compound having a thiocyanate structure, so that the reaction between the silane coupling agent and the polymer without adversely affecting the scorch stability and processability. Has been found to be able to be further promoted, and the present invention has been completed.

That is, the present invention
[1] A rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and the following general formula (1) A rubber composition comprising a compound (D) having a thiocyanate structure represented by:

(In the formula, X ^{n +} is a sodium ion, a lithium ion, a monovalent copper ion, a potassium ion, a guanidinium ion, and a quaternary ammonium ion represented by NR ₄ ⁺ (R is a hydrogen atom or a carbon number of 1 to 10). And at least one monovalent cation selected from the group consisting of calcium ions, barium ions, cobalt ions, divalent copper ions and zinc ions. The compound (D) having a thiocyanate structure may be a hydrate.
[2] The above compound [D], wherein the compound (D) having a thiocyanate structure is at least one compound selected from ammonium thiocyanate, sodium thiocyanate, and bis (thiocyanate) zinc represented by the following formula (1-a): ], The rubber composition according to

[3] A rubber component (A) composed of at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and the following general formula (1) And a compound (D) having a thiocyanate structure represented by formula (D), wherein the rubber composition is kneaded in a plurality of stages, and in the first stage of kneading, the rubber component (A) A rubber composition characterized by kneading all or part of the inorganic filler (B), all or part of the silane coupling agent (C), and the compound (D) having the thiocyanate structure. Manufacturing method, and

(In the formula, X ^{n +} is a sodium ion, a lithium ion, a monovalent copper ion, a potassium ion, a guanidinium ion, and a quaternary ammonium ion represented by NR ₄ ⁺ (R is a hydrogen atom or a carbon number of 1 to 10). And at least one monovalent cation selected from the group consisting of calcium ions, barium ions, cobalt ions, divalent copper ions and zinc ions. The compound (D) having a thiocyanate structure may be a hydrate.
[4] The rubber composition described in [1] or [2] above or the rubber composition obtained by the method described in [3] above is provided on at least one member. tire,
Is to provide.

  According to the present invention, the reaction between the silane coupling agent and the polymer is further accelerated without adversely affecting the scorch stability and processability, and a low heat-generating rubber composition and a pneumatic tire using the same are provided. can do.

First, the rubber composition of the present invention will be described.
[Rubber composition]
The rubber composition of the present invention comprises at least one rubber component (A) selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and It is characterized by comprising a compound (D) having a thiocyanate structure represented by the general formula (1).

In the formula, X ^{n +} is a sodium ion, a lithium ion, a monovalent copper ion, a potassium ion, a guanidinium ion, and a quaternary ammonium ion represented by NR ₄ ⁺ (R is a hydrogen atom or a carbon number of 1 to 10). An at least one monovalent cation selected from the group consisting of a calcium ion, a barium ion, a cobalt ion, a divalent copper ion and a zinc ion. A divalent cation, n is 1 or 2, and the compound (D) having a thiocyanate structure may be a hydrate.
Among these, the compound (D) having a thiocyanate structure is at least one compound selected from ammonium thiocyanate, sodium thiocyanate and zinc bis (thiocyanate) represented by the following formula (1-a). However, it is preferable because the reaction between the silane coupling agent and the polymer is further promoted to improve the low heat generation property and the wear resistance is further improved.

The compounding quantity of the compound (D) which has a thiocyanate structure shown by the said General formula (1) in the rubber composition in this invention is 0.01-10 mass parts with respect to 100 mass parts of rubber components (A). It is preferably 0.02 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, and particularly preferably 0.1 to 8 parts by mass.
The compounding mass ratio of the compound (D) having a thiocyanate structure represented by the above general formula (1) in the rubber composition in the present invention to the silane coupling agent (C) {compound having a thiocyanate structure (D) / silane The coupling agent (C)} is preferably (2/100) to (100/100). If it is (2/100) or more, the silane coupling agent (C) is sufficiently activated, and if it is (100/100) or less, the vulcanization rate is not greatly affected. More preferably, the compounding mass ratio of the compound (D) having a thiocyanate structure in the rubber composition to the silane coupling agent (C) {the compound (D) having a thiocyanate structure / silane coupling agent (C)} is ( 4/100) to (80/100), particularly preferably (4/100) to (50/100).

Since the compound (D) having a thiocyanate structure is usually solid at room temperature, it is used as a carrier supported on powder, granulated material, silica, or the like, for example, a silica carrier.
From the viewpoint of efficiently dispersing the rubber composition during kneading, it is preferably used as a silica support.
Next, the manufacturing method of the rubber composition of this invention is demonstrated.

[Method for producing rubber composition]
The method for producing a rubber composition of the present invention comprises a rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), and a silane coupling agent (C). And a method of producing a rubber composition comprising the compound (D) having a thiocyanate structure represented by the general formula (1), wherein the rubber composition is kneaded in a plurality of stages, and the first stage of kneading. And kneading the rubber component (A), all or part of the inorganic filler (B), all or part of the silane coupling agent (C), and the compound (D) having the thiocyanate structure. It is characterized by.
Next, a rubber component (A), a filler containing an inorganic filler (B), silica, carbon black, and a silane coupling agent (C) used in the rubber composition of the present invention and the manufacturing method thereof will be described. .

[Rubber component (A)]
The rubber component (A) used in the rubber composition and the method for producing the same of the present invention comprises at least one selected from natural rubber and synthetic diene rubber. Here, as the synthetic diene rubber, styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), Halogenated butyl rubber (Cl-IIR, Br-IIR, etc.), ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-butadiene copolymer rubber, propylene-butadiene copolymer rubber, etc. can be used. Natural rubber and synthetic diene rubber may be used singly or as a blend of two or more.

[Inorganic filler (B)]
As the inorganic filler (B) used in the rubber composition and the production method thereof of the present invention, silica and an inorganic compound represented by the following general formula (2) can be used.
dM ¹ · xSiO _y · zH ₂ O (2)
Here, in the general formula (VIII), M ¹ is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium, and zirconium, oxides or hydroxides of these metals, and hydrates thereof, Or at least one selected from carbonates of these metals, and d, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10 is there.
In the general formula (2), when both x and z are 0, the inorganic compound is at least one metal, metal oxide or metal hydroxide selected from aluminum, magnesium, titanium, calcium and zirconium. It becomes.

(silica)
In the present invention, among the inorganic fillers (B), silica is preferable from the viewpoint of achieving both low rolling properties and wear resistance. Any commercially available silica can be used, among which wet silica, dry silica, and colloidal silica are preferably used, and wet silica is particularly preferably used. The BET specific surface area (measured in accordance with ISO 5794/1) of silica is preferably 40 to 350 m ² / g. Silica having a BET surface area within this range has an advantage that both rubber reinforcement and dispersibility in a rubber component can be achieved. In this respect, BET surface area is more preferably silica in the range of 80~350m ² / g, silica BET surface area in the range of 120~350m ² / g is particularly preferred. Examples of such silica include Tosoh Silica Co., Ltd., trade name “Nip Seal AQ” (BET specific surface area = 205 m ² / g), “Nip Seal KQ”, and Degussa's trade name “Ultra Gil VN 3” (BET specific surface area = 175 m ² / g) can be used.

As the inorganic compound represented by the general formula (2), .gamma.-alumina, alumina (Al ₂ O ₃₎ such as α- alumina, boehmite, alumina monohydrate such as diaspore _{(Al 2 O 3 · H 2} O ), Aluminum hydroxide such as gibbsite, bayerite [Al (OH) ₃ ], aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white (TiO _2), titanium black (TiO _2n-1), calcium oxide (CaO) , calcium hydroxide [Ca (OH) _2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), kaolin ( _{l 2 O 3 · 2SiO 2 ·} 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ · 3SiO ₄ · 5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O], zirconium carbonate [ Zr (CO _{3) 2],} hydrogen to correct electric charge as various zeolites, such as crystalline aluminosilicates including alkali metal or alkaline earth metal is used It can be. Further, it is preferable that M ¹ in the general formula (2) is at least one selected from aluminum metal, aluminum oxide or hydroxide, hydrates thereof, and aluminum carbonate.
These inorganic compounds represented by the general formula (2) may be used alone or in combination of two or more. The average particle diameter of these inorganic compounds is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.02 to 10 μm, from the viewpoint of kneading workability, wear resistance and wet grip performance. The range of 0.02 to 5 μm is more preferable, and the range of 0.02 to 0.20 μm is preferable.
The inorganic filler (B) in the present invention may be used alone or in combination with silica and one or more inorganic compounds represented by the general formula (2).

  The inorganic filler (B) used in the rubber composition and the method for producing the same of the present invention is preferably used in an amount of 20 to 120 parts by mass with respect to 100 parts by mass of the rubber component (A). If it is 20 mass parts or more, it is preferable from a viewpoint of ensuring wet performance, and if it is 120 mass parts or less, it is preferable from a viewpoint of rolling resistance reduction. Furthermore, it is more preferable to use 30-100 mass parts.

(Carbon black)
The filler used in the rubber composition and the method for producing the same of the present invention may contain carbon black in addition to the above-described inorganic filler (B), if desired. By containing carbon black, it is possible to enjoy the effect of reducing electrical resistance and suppressing charging. The carbon black is not particularly limited. For example, high, medium or low structure SAF, ISAF, IISAF, N339, HAF, FEF, GPF, SRF grade carbon black, particularly SAF, ISAF, IISAF, N339, HAF, Preferably, FEF grade carbon black is used. The nitrogen adsorption specific surface area (N ₂ SA, measured in accordance with JIS K 6217-2: 2001) is preferably 30 to 250 m ² / g. This carbon black may be used individually by 1 type, and may be used in combination of 2 or more type. In the present invention, carbon black is not included in the inorganic filler (B).

[Filler]
The filler of the rubber composition according to the present invention is preferably used in an amount of 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component (A). If it is 20 mass parts or more, it is preferable from a viewpoint of the reinforcement property improvement of a rubber composition, and if it is 150 mass parts or less, it is preferable from a viewpoint of rolling resistance reduction.
In the filler, the inorganic filler (B) is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 70% by mass or more.
In addition, when using a silica as an inorganic filler (B), it is preferable that the silica in the said filler is 30 mass% or more.

[Silane coupling agent (C)]
The silane coupling agent (C) used in the rubber composition of the present invention and the production method thereof is a compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV). Is preferred.
By using such a silane coupling agent (C), the rubber composition of the present invention can be further improved in workability during rubber processing and can provide a tire with better wear resistance.
Hereinafter, the following general formulas (I) to (IV) will be described in order.

In the formula, when there are a plurality of R ^{1 s} , they may be the same or different, and each of them may be a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, or a linear or branched alkoxy group having 2 to 8 carbon atoms. A substituent selected from an alkyl group and a silanol group, and when there are a plurality of R ^{2 s} , they may be the same or different and each is a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms; ³ may be the same or different when there are a plurality, and each is a linear or branched alkylene group having 1 to 8 carbon atoms. a is an average value of 2 to 6, and p and r may be the same or different, and are each an average value of 0 to 3. However, both p and r are not 3.

  Specific examples of the silane coupling agent (C) represented by the general formula (I) include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (3-methyl). Dimethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (3-methyldimethoxysilylpropyl) Disulfide, bis (2-triethoxysilylethyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-methyldimethoxysilylpropyl) trisulfide Bis (2-triethoxysilylethyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) tetrasulfide, bis (3-monoethoxydimethylsilylpropyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) Disulfide, bis (3-monomethoxydimethylsilylpropyl) tetrasulfide, bis (3-monomethoxydimethylsilylpropyl) trisulfide, bis (3-monomethoxydimethylsilylpropyl) disulfide, bis (2-monoethoxydimethylsilylethyl) Examples thereof include tetrasulfide, bis (2-monoethoxydimethylsilylethyl) trisulfide, and bis (2-monoethoxydimethylsilylethyl) disulfide.

Wherein, R ⁴ is ^{-Cl, -Br, R 9 O-,} R 9 C (= O) O-, R 9 R 10 C = NO-, R 9 R 10 CNO-, R 9 R 10 N-, And-(OSiR ⁹ R ¹⁰ ) _h (OSiR ⁹ R ¹⁰ R ¹¹ ) are each a monovalent group (R ⁹ , R ¹⁰ and R ¹¹ are each a hydrogen atom or a monovalent hydrocarbon having 1 to 18 carbon atoms. H is an average value of 1 to 4, and R ⁵ is R ⁴ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ⁶ is R ⁴ , R ⁵ , a hydrogen atom or a — [O (R ¹² O) _j ] _0.5 — group (R ¹² is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4), and R ⁷ is a carbon number. A divalent hydrocarbon group having 1 to 18 carbon atoms, and R ⁸ is a monovalent hydrocarbon group having 1 to 18 carbon atoms. x, y, and z are numbers satisfying the relationship of x + y + 2z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1.

In the above general formula (II), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ may be the same or different, preferably each a straight-chain, cyclic or branched alkyl group or alkenyl group having 1 to 18 carbon atoms. And a group selected from the group consisting of an aryl group and an aralkyl group. When R ⁵ is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is a group selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. Preferably there is. R ¹² is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ⁷ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene having 6 to 18 carbon atoms. And aralkylene groups having 7 to 18 carbon atoms. The alkylene group and alkenylene group may be linear or branched, and the cycloalkylene group, cycloalkylalkylene group, arylene group, and aralkylene group have a substituent such as a lower alkyl group on the ring. You may have. R ⁷ is preferably an alkylene group having 1 to 6 carbon atoms, particularly preferably a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group. it can.

Specific examples of the monovalent hydrocarbon group having 1 to 18 carbon atoms of R ⁵ , R ⁸ , R ⁹ , R ¹⁰ and R ^{11 in} the general formula (II) include a methyl group, an ethyl group, and an 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 group, cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
Examples of R ¹² in the general formula (II) include methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, octamethylene group, decamethylene group, dodecamethylene group and the like.

  Specific examples of the silane coupling agent (C) represented by the general formula (II) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltri Ethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane Down, 2-octanoylthiopropyl ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane. Among these, 3-octanoylthiopropyltriethoxysilane (manufactured by Momentive Performance Materials, trademark “NXT silane”) is particularly preferable.

In the formula, when there are a plurality of R ^{13 s} , they may be the same or different, and each of them may be a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, or a linear or branched alkoxy group having 2 to 8 carbon atoms. A substituent selected from an alkyl group and a silanol group, and when there are a plurality of R ^{14 s} , they may be the same or different and each is a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms; ^When there are a plurality of ^15s , they may be the same or different and each is a linear or branched alkylene group having 1 to 8 carbon atoms. R ¹⁶ is selected from the general formulas (—S—R ¹⁷ —S—), (—R ¹⁸ —S _m1 —R ¹⁹ —) and (—R ²⁰ —S _m2 —R ²¹ —S _m3 —R ²² —). Divalent groups (R ^{17 to} R ²² are each selected from a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent aromatic group, and a divalent organic group containing a hetero element other than sulfur and oxygen. Each of m1, m2 and m3 is an average value of 1 or more and less than 4, and a plurality of k's may be the same or different, and each of the average values is 1 to 6 , S, and t are 0 to 3 as average values. However, both s and t are not 3.

As a specific example of the silane coupling agent (C) represented by the general formula (III),
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 - (CH 2) 6 -S 2 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 - (CH 2) 10 -S 2 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 3 - (CH 2) 6 -S 3 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average composition formula (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S ₄ — (CH ₂ ) ₆ —S ₄ — (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ ,
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 2 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH 3 ₃
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 2.5 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH 3 ₃
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 3 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH 3 ₃
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 4 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH 3 ₃
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 10 -S 2 - (CH 2) 10 -S- (CH 2) 3 -Si (OCH 2 CH 3 ₃
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 4 - (CH 2) 6 -S 4 - (CH 2) 6 -S 4 - (CH 2) 3 -Si (OCH 2 CH _{3) 3,}
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S 2 - (CH 2) 6 -S 2 - (CH 2) 6 -S 2 - (CH 2) 3 -Si (OCH 2 CH _{3) 3,}
Average composition formula _{(CH 3 CH 2 O) 3} Si- (CH 2) 3 -S- (CH 2) 6 -S 2 - (CH 2) 6 -S 2 - (CH 2) 6 -S- (CH 2 The compound represented by _3- Si (OCH ₂ CH ₃ ) _{3 and the} like is preferably exemplified. The silane coupling agent (C) represented by the general formula (III) is, for example, International Publication No. 2004/000930, It can be produced by the method described in Japanese Unexamined Patent Publication No. 2006-167919.

In the formula, R ²³ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and a plurality of Gs may be the same or different, and each is an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms. There, the plurality of Z ^a may be the same or different, is a functional group capable of binding with each of two silicon atoms, and _{[-O-] 0.5, [- O} -G-] 0.5 and [- O—G—O—] is a functional group selected from _0.5 , and a plurality of Z ^b may be the same or different, each being a functional group capable of bonding to two silicon atoms, and [—O— G-O-] _0.5 is a functional group, and a plurality of Z ^c may be the same or different, and each represents —Cl, —Br, —OR ^e , R ^e C (═O) O—, R ^{e R f C = NO-, R} e R f N-, R e - and HO-G-O- (G coincides with the notation.) selected from Is a functional group, R ^e and R ^f are each linear having 1 to 20 carbon atoms, branched or cyclic alkyl group. m, n, u, v and w are 1 ≦ m ≦ 20, 0 ≦ n ≦ 20, 0 ≦ u ≦ 3, 0 ≦ v ≦ 2, 0 ≦ w ≦ 1, and (u / 2) + v + 2w. = 2 or 3. When there are a plurality of A parts, each of Z ^a _u , Z ^b _v and Z ^c _w in the plurality of A parts may be the same or different. When there are a plurality of B parts, Z ^a in the plurality of B parts Each of _u , Z ^b _v and Z ^c _w may be the same or different.

As specific examples of the silane coupling agent (C) represented by the general formula (IV), a trademark “NXT Low-V Silane” manufactured by Momentive Performance Materials, a trademark “NXT Ultra Low-V Silane” manufactured by Momentive Performance Materials, Inc. ", Trademark" NXT-Z "manufactured by Momentive Performance Materials is available as a commercial product.
The silane coupling agent obtained by the above general formula (II) and chemical formula (IV) has a protected mercapto group and prevents the occurrence of initial vulcanization (scorch) during processing in the process prior to the vulcanization process. Therefore, workability is improved.
Moreover, since the silane coupling agent represented by the general formula (IV) has a large number of alkoxysilane carbon atoms, the generation of the volatile compound VOC (particularly alcohol) is small, which is preferable in the work environment.

  The blending mass ratio {silane coupling agent (C) / inorganic filler (B)} of the silane coupling agent (C) in the rubber composition according to the present invention to the inorganic filler (B) is (1/100). It is preferable that it is (60/100). If it is (1/100) or more, the effect of improving the low heat build-up of the rubber composition will be exhibited, and if it is (60/100) or less, the cost of the rubber composition will not be excessive, so the economy will be improved. Because. Furthermore, the blending mass ratio {silane coupling agent (C) / inorganic filler (B)} is more preferably (3/100) to (50/100), and (3/100) to (20 / 100) is particularly preferred.

Next, the manufacturing method of the rubber composition of this invention is demonstrated in detail.
As described above, the method for producing a rubber composition of the present invention is a method for producing a rubber composition of the present invention, wherein the rubber composition is kneaded in a plurality of stages, and natural rubber and synthesis are performed in the first stage of kneading. In the rubber component (A) comprising at least one selected from diene rubbers, all or part of the inorganic filler (B), all or part of the silane coupling agent (C), and the above general formula (1) The compound (D) having the thiocyanate structure shown is kneaded. In the first stage of this kneading, zinc oxide (E) may be used as an activator.

  In the present invention, if desired, zinc oxide (E) used as an activator is also called zinc white and is represented as ZnO. Zinc flower for rubber is commercially available from Sakai Chemical Industry Co., Ltd., Shodo Chemical Industry Co., Ltd., Toho Zinc Co., Ltd., and Hakusui Tech Co., Ltd.

  In order to improve the dispersion of the inorganic filler such as silica in the rubber composition, the maximum temperature of the rubber composition in the first stage of kneading is preferably 120 to 190 ° C., and 130 to 180 More preferably, it is 140 degreeC, and it is still more preferable that it is 140-175 degreeC. The kneading time is preferably from 10 seconds to 20 minutes, more preferably from 10 seconds to 10 minutes, and further preferably from 30 seconds to 5 minutes.

  In the present invention, in the first stage of kneading, the rubber component (A), all or part of the inorganic filler (B), and all or part of the silane coupling agent (C) are simultaneously described above. The compound (D) having a thiocyanate structure represented by the general formula (1) and the desired zinc oxide (E) may be kneaded, or all of the rubber component (A) and the inorganic filler (B). Alternatively, after kneading a part and all or part of the silane coupling agent (C), the compound (D) having the thiocyanate structure and the desired zinc oxide (E) may be added and further kneaded. In this case, in the first stage of kneading, all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C) are kneaded, and kneading is started. Within 180 seconds (0 to 180 seconds), the compound (D) having the thiocyanate structure and the desired zinc oxide (E) are preferably added and further kneaded. In the first stage of kneading, after adding all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C), the first stage During the process, the time until the compound (D) having a thiocyanate structure and the desired zinc oxide (E) are added is from the start of kneading until the compound (D) having the thiocyanate structure and the desired zinc oxide (E) are added. More preferably, the time is 10 to 180 seconds. The upper limit of this time is more preferably 150 seconds or less, and particularly preferably 120 seconds or less. If this time is 10 seconds or more, the reaction of (B) and (C) can be sufficiently advanced. Even if this time exceeds 180 seconds, the reaction of (B) and (C) has already proceeded sufficiently, so that it is difficult to enjoy further effects, and the upper limit is preferably set to 180 seconds.

The kneading step of the rubber composition in the production method of the present invention includes at least two stages of a first stage of kneading without compounding the vulcanizing agent and a final stage of kneading with compounding the vulcanizing agent. Accordingly, an intermediate stage of kneading without blending a vulcanizing agent may be included. Here, the vulcanizing agent is a substance that can crosslink a polymer chain of a conjugated diene rubber, which is a plastic material, in a network, and sulfur is a representative example. Vulcanizing agents are roughly classified into inorganic vulcanizing agents and organic vulcanizing agents. Specific examples of the former include sulfur (powder sulfur, sulfur white, deoxidized sulfur, precipitated sulfur, colloidal sulfur, high molecular weight. Sulfur, insoluble sulfur), and sulfur monochloride. Specific examples of the latter include those capable of releasing active sulfur by thermal dissociation of morphodisulfide, alkylphenol disulfide, and the like. Specific examples of other organic sulfur-containing vulcanizing agents include the Japan Rubber Association, “Rubber Industry Handbook 4th Edition” (published by the Japan Rubber Association in January 1994). It is described in the vulcanizing agent.
The first stage of kneading in the present invention refers to the first stage of kneading the rubber component (A), the inorganic filler (B) and the silane coupling agent (C). In the first stage, silane coupling is performed. The step of kneading the rubber component (A) and the filler without adding the agent (C) or preliminarily kneading only the rubber component (A) is not included.

If it is difficult to produce a master batch only by the first stage of kneading, or if desired, an intermediate stage of kneading may be provided after the first stage of kneading.
When the intermediate stage after the first stage and before the final stage is included, the maximum temperature of the rubber composition in the intermediate stage of kneading is preferably 120 to 190 ° C, and preferably 130 to 175 ° C. More preferably, it is 140-170 degreeC. The kneading time is preferably from 10 seconds to 20 minutes, more preferably from 10 seconds to 10 minutes, and further preferably from 30 seconds to 5 minutes. In addition, when including an intermediate | middle stage, it is preferable to advance to the next stage, after lowering | hanging 10 degreeC or more from the temperature after completion | finish of the kneading | mixing of the previous stage.
The final stage of kneading refers to a process of blending and kneading a vulcanizing agent. The maximum temperature of the rubber composition in this final stage is preferably 60 to 140 ° C, more preferably 80 to 120 ° C, and still more preferably 100 to 120 ° C. The kneading time is preferably 10 seconds to 20 minutes, more preferably 10 seconds to 10 minutes, and even more preferably 20 seconds to 5 minutes.
When proceeding from the first stage and the intermediate stage to the final stage, it is preferable to proceed to the next stage after lowering the temperature by 10 ° C. or more from the temperature after completion of the previous stage of kneading.
For example, in the first stage of kneading, all or part of the rubber component (A), the inorganic filler (B), and all or part of the silane coupling agent (C) are kneaded and cured by natural cooling. Thereafter, as an intermediate stage, the compound (D) having a thiocyanate structure and zinc oxide (E) as desired may be added and kneaded to form a master batch kneading stage.

The rubber composition of the present invention and the silane coupling agent (C) used in the production method thereof are compounds selected from the group consisting of the compounds represented by the general formulas (I) to (IV) described above. It is preferable that
By using such a silane coupling agent (C), the rubber composition of the present invention can be further improved in workability during rubber processing and can provide a tire with better wear resistance.

  Further, the compounding mass ratio of the compound (D) having a thiocyanate structure represented by the general formula (1) in the rubber composition in the first stage of the kneading to the silane coupling agent (C) {the compound having a thiocyanate structure ( D) / Silane coupling agent (C)} is preferably (2/100) to (100/100). If it is (2/100) or more, the silane coupling agent (C) is sufficiently activated, and if it is (100/100) or less, the vulcanization rate is not greatly affected. More preferably, the compounding mass ratio of the compound (D) having a thiocyanate structure in the rubber composition in the first stage of kneading to the silane coupling agent (C) {the compound (D) having a thiocyanate structure / silane coupling agent ( C)} is (4/100) to (80/100), particularly preferably (4/100) to (50/100).

The silane coupling agent (C) according to the present invention is particularly preferably a compound represented by the general formula (I) among the compounds represented by the general formulas (I) to (IV). This is because the compound (D) having a thiocyanate structure easily causes activation of a polysulfide bond site that reacts with the rubber component (A).
In this invention, a silane coupling agent (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

In the rubber composition of the present invention, the compounding amount of zinc oxide (E) optionally added to the rubber composition in the first stage of kneading is 0.5 to 100 parts by mass with respect to 100 parts by mass of the rubber component (A). It is preferably 4 parts by mass.
Here, the blending amount of zinc oxide (E) in the rubber composition in the first stage of the kneading is preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the rubber component (A). Has an effect of suppressing an increase in viscosity of the unvulcanized rubber composition if the blending amount of zinc oxide (E) is 0.5 parts by mass or more, and if it is 4 parts by mass or less, a coupling agent and a rubber component This is because the reactivity improvement effect can be enjoyed. More preferably, the compounding amount of zinc oxide (E) in the rubber composition in the first stage of kneading is 0.5 to 2 parts by mass, more preferably 100 parts by mass of the rubber component (A). 0.5 to 1.5 parts by mass.

  Further, the blending mass ratio of zinc oxide (E) to the silane coupling agent (C) optionally added to the rubber composition in the first stage of the kneading {zinc oxide (E) / silane coupling agent (C)} Is preferably (10/100) to (1000/100). If the blending mass ratio is (10/100) or more, the effect of suppressing an increase in the viscosity of the unvulcanized rubber composition is suitably exhibited, and if it is (1000/100) or less, the coupling agent and the rubber are preferable. Since the effect of improving the reactivity with the components can be suitably enjoyed, it is preferable. The blending mass ratio {zinc oxide (E) / silane coupling agent (C)} of zinc oxide (E) to the silane coupling agent (C) optionally added to the rubber composition in the first stage of kneading is further Preferably they are (10/100)-(100/100), Most preferably, they are (10/100)-(50/100).

In the method for producing a rubber composition of the present invention, various compounding agents such as a vulcanization activator such as stearic acid and resin acid, an anti-aging agent and the like, which are usually compounded in the rubber composition, are first kneaded as necessary. It is kneaded in the stage or the final stage, or in the intermediate stage between the first stage and the final stage.
As a kneading apparatus in the production method of the present invention, a Banbury mixer, a meshing mixer (internal mixer), a roll, an intensive mixer, a kneader, a twin screw extruder, or the like is used.

The present invention also provides a tire characterized in that the rubber composition obtained by the above-described rubber composition and the above-described production method is disposed on at least one member.
By using the rubber composition obtained by the above-described rubber composition and the above-mentioned production method as the rubber composition, a tire excellent in low heat buildup and wear resistance can be provided, and the processing of the unvulcanized rubber composition Good properties.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
The low exothermic property (tan δ index) and the wear resistance (index) were evaluated by the following methods.

Low exothermicity (tan δ index)
Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Ueshima Seisakusho, measurement was performed at a frequency of 52 Hz, an initial strain of 10%, a measurement temperature of 60 ° C., and a dynamic strain of 1%. Was expressed as an index according to the following formula. A larger index value indicates a lower exothermic property and a smaller hysteresis loss.
Low exothermic index = {(tan δ of vulcanized rubber composition of Comparative Example 1 or 5) / (tan δ of test vulcanized rubber composition)} × 100

Abrasion resistance (index)
In accordance with JIS K6264-2: 2005, a wear amount of a slip rate of 60% at room temperature (23 ° C.) was measured using a Lambourn wear tester, and the reciprocal of the wear amount was determined as the wear amount of Comparative Example 1 or 5. 100 was expressed as an index according to the following formula. The larger this value, the better the wear resistance, and it is preferable that the index exceeds 100.
Abrasion resistance index = {Amount of wear of the vulcanized rubber composition of Comparative Example 1 or 5) / Amount of wear of the test vulcanized rubber composition} × 100

Production Example 1
Average composition formula (CH ₃ CH ₂ O) ₃ Si- (CH ₂ ) ₃ -S- (CH ₂ ) ₆ -S _2.5- (CH ₂ ) ₆ -S- (CH ₂ ) ₃ -Si (OCH ₂ CH ₃ The silane coupling agent represented by ₃ was produced as follows.
Into a 2 liter separable flask equipped with a nitrogen gas introduction tube, a thermometer, a Dimroth condenser and a dropping funnel, 119 g (0.5 mol) of 3-mercaptopropyltriethoxysilane was charged, and 20% of the active ingredient was stirred. 151.2 g (0.45 mol) of an ethanol solution of sodium ethoxide was added. Thereafter, the temperature was raised to 80 ° C., and stirring was continued for 3 hours. Then it was cooled and transferred to a dropping funnel.
Next, 69.75 g (0.45 mol) of 1,6-dichlorohexane was charged into a separable flask similar to the above, heated to 80 ° C., and then the above 3-mercaptopropyltriethoxysilane and sodium ethoxide were added. The reaction was slowly added dropwise. After completion of dropping, stirring was continued at 80 ° C. for 5 hours. Thereafter, the mixture was cooled, and the salt was filtered off from the resulting solution. Ethanol and excess 1,6-dichlorohexane were distilled off under reduced pressure. The resulting solution was distilled under reduced pressure to obtain 137.7 g of a colorless transparent liquid having a boiling point of 148 to 150 ° C./0.005 torr. As a result of IR analysis, ¹ H-NMR analysis and mass spectrum analysis (MS analysis), a compound represented by (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ S— (CH ₂ ) ₆ —Cl Met. The purity by gas chromatographic analysis (GC analysis) was 97.5%.
Next, 80 g of ethanol, 5.46 g (0.07 mol) of anhydrous sodium sulfide and 3.36 g (0.105 mol) of sulfur were charged into a 0.5 liter separable flask similar to the above, and the temperature was raised to 80 ° C. did. While stirring this solution, 49.91 g (0.14 mol) of the above (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S— (CH ₂ ) ₆ —Cl was slowly added dropwise. After completion of dropping, stirring was continued at 80 ° C. for 10 hours. After completion of the stirring, the mixture was cooled and the formed salt was filtered off, and then ethanol as a solvent was distilled under reduced pressure.
The obtained reddish-brown transparent solution was subjected to IR analysis, ¹ H-NMR analysis and supercritical chromatography analysis.
(CH ₃ CH ₂ O) ₃ Si- (CH ₂ ) ₃ -S- (CH ₂ ) ₆ -S _2.5- (CH ₂ ) ₆ -S- (CH ₂ ) ₃ -Si (OCH ₂ CH ₃ ) ₃ It was confirmed that the compound was represented. The purity of this product by GPC analysis was 85.2%.

Examples 1-10 and Comparative Examples 1-4
According to the formulation and kneading method shown in Table 1, the maximum temperature of the rubber composition in the first stage of kneading is adjusted to 150 ° C. and kneaded with a Banbury mixer to prepare 14 types of rubber compositions. did. In the first stage of kneading in Examples 1 to 10 and Comparative Examples 1 to 4, the rubber component (A), all of the inorganic filler (B), all of the silane coupling agent (C) and aromatic oil were kneaded. 120 seconds after the start of kneading, Examples 1 to 10 were further kneaded by adding the compound (D) having a thiocyanate structure.
On the other hand, in Comparative Examples 1 to 4, in the first stage of kneading, the rubber component (A), all of the inorganic filler (B), all of the silane coupling agent (C), and aromatic oil are kneaded to form a thiocyanate structure. The kneading was further carried out without adding the compound (D), but zinc oxide (E) was added at the final stage of kneading. In Example 10, the compound (D) having a thiocyanate structure was added and further kneaded at the final stage of kneading.
The resulting 14 types of rubber compositions were vulcanized at a vulcanization temperature of 165 ° C. The vulcanization time was t _c (90) value (minutes) × 1.5 times. Here, t _c (90) values JIS K 6300-2: a t _c (90) values defined in 2001. The low exothermic property (tan δ index) and the wear resistance (index) of the obtained 14 kinds of vulcanized rubber compositions were evaluated by the above methods. The results are shown in Table 1.

[note]
* 1: JSR emulsion polymerization SBR, trade name "JSR 1500"
* 2: RSS # 3
* 3: N220 (ISAF), manufactured by Asahi Carbon Co., Ltd., trade name “# 80”
* 4: Tosoh Silica Co., Ltd., trade name “Nip Seal AQ”, BET surface area 205 m ² / g
* 5: Bis (3-triethoxysilylpropyl) disulfide (average sulfur chain length: 2.35), silane coupling agent manufactured by Evonik, trade name “Si75” (registered trademark)
* 6: 3-octanoylthiopropyltriethoxysilane, manufactured by Monentive Performance Materials, trade name “NXT silane” (registered trademark)
* 7: Silane coupling agent represented by the above chemical formula (VIII), Monentive Performance
Product name “NXT-Z” (registered trademark)
* 8: Silane coupling agent obtained in Production Example 1
Average composition formula (CH ₃ CH ₂ O) ₃ Si- (CH ₂ ) ₃ -S- (CH ₂ ) ₆ -S _2.5- (CH ₂ ) ₆ -S- (CH ₂ ) ₃ -Si (OCH ₂ CH ₃ ) ₃
* 9: Compound (B)-(a): ammonium thiocyanate, manufactured by Kanto Chemical Co., Ltd. * 10: Compound (B)-(b): Sodium thiocyanate, manufactured by Kanto Chemical Co., Ltd. * 11: Compound (B)- (C): Zinc bis (thiocyanate), manufactured by Kanto Chemical Co., Ltd. * 12: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine,
Product name "NOCRACK 6C" manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 13: 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller D”
* 14: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 224”
* 15: Di-2-benzothiazolyl disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sanseller DM”
* 16: N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller NS”

Examples 11-20 and Comparative Examples 5-8
According to the formulation and kneading method shown in Table 2, the maximum temperature of the rubber composition in the first stage of kneading is adjusted to 150 ° C. and kneaded with a Banbury mixer to prepare 14 types of rubber compositions. did. In the first stage of the kneading of Examples 11 to 20 and Comparative Examples 5 to 8, the rubber component (A), the inorganic filler (B), the silane coupling agent (C), and the aromatic oil were kneaded. 120 seconds after the start of kneading, Examples 11 to 20 were further kneaded by adding the compound (D) having a thiocyanate structure.
On the other hand, in Comparative Examples 5 to 8, in the first stage of kneading, all of the rubber component (A), the inorganic filler (B), all of the silane coupling agent (C) and aromatic oil are kneaded to form a thiocyanate structure. The kneading was further carried out without adding the compound (D), but zinc oxide (E) was added at the final stage of kneading. In Example 20, the compound (D) having a thiocyanate structure was added and kneaded at the final stage of kneading.
The resulting 14 types of rubber compositions were vulcanized at a vulcanization temperature of 165 ° C. The vulcanization time was t _c (90) value (minutes) × 1.5 times. Here, t _c (90) values JIS K 6300-2: a t _c (90) values defined in 2001. The low exothermic property (tan δ index) and the wear resistance (index) of the obtained 14 kinds of vulcanized rubber compositions were evaluated by the above methods. The results are shown in Table 2.

[note]
* 1 to 16 are the same as described in Table 1.

As is clear from Table 1, the rubber compositions of Examples 1 to 10 all have low heat build-up (tan δ index) and resistance compared to the rubber compositions to be compared in Comparative Examples 1 to 4. Abrasion (index) is better.
Further, as is clear from Table 2, the rubber compositions of Examples 11 to 20 are all less heat-generating (tan δ index) than the rubber compositions to be compared in Comparative Examples 5 to 8. And wear resistance (index) is better.

  According to the method for producing a rubber composition of the present invention, a rubber composition excellent in low heat buildup and wear resistance can be obtained, so that it is used for passenger cars, small trucks, light passenger cars, light trucks and large vehicles. {Treating parts for various tires such as for trucks and buses, for off-the-road tires (for mining vehicles, construction vehicles, etc.)}, preferably pneumatic radial tire treads, especially treads for pneumatic radial tires The rubber composition is preferably used for the production of a member for a part.

Claims (3)

A rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and the following formula (1-a) ammonium thiocyanate which, Ri name by blending a sodium thiocyanate and bis compounds having a thiocyanate structure consisting of at least one selected from (thiocyanate) zinc (D), that the inorganic filler (B) is Do silica Rubber composition.
A rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), a silane coupling agent (C), and the following formula (1-a) A method for producing a rubber composition comprising a compound (D) having a thiocyanate structure consisting of at least one selected from ammonium thiocyanate, sodium thiocyanate, and bis (thiocyanate) zinc , comprising the inorganic filler (B) is made of silica, and the rubber composition is kneaded in a plurality of stages, and in the first stage of kneading, all or part of the rubber component (A) and the inorganic filler (B), the silane coupling A method for producing a rubber composition, comprising kneading all or part of the agent (C) and the compound (D) having the thiocyanate structure.
The rubber composition according to claim 1, tire characterized by being arranged in at least one of the members.