JP6340164B2 - Method for producing rubber composition - Google Patents

Description

  The present invention relates to a method for producing a rubber composition containing an inorganic filler that improves low heat buildup.

It is effective to use silica as a filler as a technique that achieves both low rolling resistance and high braking performance on wet road surfaces. Here, it is essential to use a silane coupling agent in combination with silica in order to further reduce loss and wear resistance. The silane coupling agent also has a role of preventing adsorption of the vulcanization accelerator to the silica surface by interacting with the silica surface.
However, when a silane coupling agent is used, unreacted components remain in the rubber, which may cause rubber burns during kneading. Therefore, by using a small amount of a silane coupling agent in combination with a nonionic surfactant, rubber with excellent low loss, wettability, wear resistance, processability, etc. without causing rubber burns It is known that a composition can be obtained (see Patent Document 1).
However, in this case, since the nonionic surfactant is rapidly adsorbed on the silica surface, the reaction between the silane coupling agent and silica is hindered. As a result, the reinforcing properties of the silica and the rubber component are lowered, and the wear resistance as the rubber composition is deteriorated.

In Patent Document 2, as a basic component, at least (i) one diene elastomer, (ii) a white filler as a reinforcing filler, and (iii) a polysulfide as a coupling agent (white filler / diene elastomer). Rubber compositions containing alkoxysilanes together with (iv) enamines and (v) guanidine derivatives have been proposed.
In Patent Document 3, as a basic component, at least (i) one diene elastomer, (ii) a white filler as a reinforcing filler, and (iii) a polysulfide as a coupling agent (white filler / diene elastomer). A rubber composition comprising an alkoxysilane together with (iv) zinc dithiophosphate and (v) a guanidine derivative is disclosed.
Patent Document 4 is based on at least (i) a diene elastomer, (ii) an inorganic filler as a reinforcing filler, and (iii) a polysulfated alkoxysilane (PSAS) as a (inorganic filler / diene elastomer) coupling agent. And (iv) a rubber composition in which aldimine (R—CH═N—R) and (v) a guanidine derivative are used in combination.
Further, in Patent Document 5, based on at least: (i) a diene elastomer, (ii) an inorganic filler as a reinforcing filler, (iii) a polysulfated alkoxysilane as a coupling agent, (iv) 1,2-dihydropyridine and ( v) Rubber compositions with guanidine derivatives have been proposed.
Patent Document 6 is an example of enhancing the activity of the coupling function of the silane coupling agent in consideration of the kneading conditions.
However, in these inventions, the reaction between the silane coupling agent and the rubber component is not sufficient, and there is room for improvement from the viewpoint of improving low heat build-up.

Japanese Patent Laid-Open No. 11-130908 Special table 2002-521515 gazette Special table 2002-521516 gazette Japanese translation of PCT publication No. 2003-530443 Special table 2003-523472 gazette International Publication No. 2008/123306 Pamphlet

  Under such circumstances, an object of the present invention is to provide a method for producing a rubber composition that improves the reactivity between a coupling agent and a rubber component and is excellent in low heat build-up.

In order to solve the above problems, the present inventors have formulated a rubber composition comprising a rubber component (A) composed of at least one selected from natural rubber and synthetic diene rubber, and a filler containing an inorganic filler. As a result, it was found that the activity of the coupling function can be further improved by surface-treating the inorganic filler and blending thioureas, thereby completing the present invention.
That is, the present invention
[1] At least one rubber component (A) selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B) surface-treated with a sulfur-containing silane coupling agent, and thiourea and carbon A method for producing a rubber composition comprising at least one thiourea compound selected from N-substituted thiourea having an alkyl group of 1 to 6 or an aromatic hydrocarbon group, wherein the rubber composition is a master batch. A rubber characterized by kneading in a plurality of stages including a kneading stage, and kneading the rubber component (A), all or part of the inorganic filler (B), and the thiourea in a kneading masterbatch kneading stage. It is a manufacturing method of a composition.

According to the present invention, by adding the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent and the thiourea at the kneading masterbatch kneading stage, the sulfur-containing silane coupling agent is silica from the beginning. Thioureas can activate the sulfur-containing silane coupling agent near the inorganic filler and improve the reaction efficiency of the sulfur-containing silane coupling agent with the polymer. Can do. Thereby, the following effects are produced.
(1) The reinforcing property of the inorganic filler such as silica and the rubber component is further improved.
(2) Since the surface treatment is performed in advance, the amount of unreacted sulfur-containing silane coupling agent is greatly reduced, and rubber scoring can be effectively prevented.
(3) Since the dispersion of the inorganic filler such as silica is efficiently improved by the surface treatment, the rubber component on the surface of the inorganic filler (B) in which the thioureas are surface-treated with the sulfur-containing silane coupling agent and Thus, the low exothermic property of the rubber composition is preferably improved.
(4) Furthermore, since thioureas can directly react with the rubber component, a further reduction in heat generation can be achieved by generating a modified rubber during kneading and improving the dispersion of the filler.
(5) Since the thiourea reacted with the rubber component can interact with silica and carbon black, it has an effect of improving dispersion of carbon black as well as inorganic fillers such as silica.
As described above, a rubber composition excellent in low heat buildup can be provided by the method for producing a rubber composition of the present invention.

The present invention is described in detail below.
The rubber composition production method of the present invention comprises a rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, and an inorganic filler (B) surface-treated with a sulfur-containing silane coupling agent. A method for producing a rubber composition comprising a filler, and at least one thiourea selected from thiourea and N-substituted thiourea having an alkyl group having 1 to 6 carbon atoms or an aromatic hydrocarbon group. The rubber composition is kneaded in a plurality of stages including a masterbatch kneading stage, and the rubber component (A), all or part of the inorganic filler (B), and the thioureas are kneaded in a masterbatch kneading stage. It is characterized by kneading.
Examples of the thioureas used in the present invention include thiourea, and N-substituted thiourea having an alkyl group having 1 to 6 carbon atoms or an aromatic hydrocarbon group. Examples of the N-substituted thiourea having an alkyl group having 1 to 6 carbon atoms, that is, the alkylthiourea having an alkyl group having 1 to 6 carbon atoms include methylthiourea, N, N′-dimethylthiourea, trimethylthiourea, ethylthiourea, N, At least one selected from N′-diethylthiourea, propylthiourea, N, N′-dipropylthiourea, butylthiourea, N, N′-dibutylthiourea, pentylthiourea, N, N′-dipentylthiourea, hexylthiourea and dihexylthiourea Preferred examples include N-substituted thiourea having an aromatic hydrocarbon group, and preferably at least one selected from N-phenylthiourea and N, N′-diphenylthiourea. Thiourea is preferred because it improves low heat build-up and wear resistance. The thiourea according to the present invention is also called thiourea, and is a white solid having a molecular formula of CH ₄ N ₂ S and a molecular weight of 76.1. Sakai Chemical Industry Co., Ltd., Mitsui Chemicals Fine Co., Ltd., Nippon Chemical Industry Co., Ltd. It is produced industrially.
N, N′-diethylthiourea, N, N′-dibutylthiourea, trimethylthiourea, N, N′-diphenylthiourea, etc. are industrially produced by Ouchi Shinsei Chemical Industry Co., Ltd., Sanshin Chemical Industry Co., Ltd. Has been produced.

In the method for producing a rubber composition of the present invention, the blending amount of thioureas in the kneading masterbatch kneading stage is preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A). It is more preferable that it is 0.05-5 mass parts, and it is still more preferable that it is 0.1-5 mass parts.
Further, the mass ratio of the amount of thiourea to the amount of sulfur-containing silane coupling agent present in the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent {thiourea amount / sulfur-containing silane coupling agent amount} Is preferably (2/100) to (100/100), more preferably (4/100) to (100/100), and (4/100) to (80/100). Is more preferable, and (4/100) to (50/100) is particularly preferable. If it is (2/100) or more, the sulfur-containing silane coupling agent is sufficiently activated, and if it is (100/100) or less, the vulcanization rate is not greatly affected.

  In order to improve dispersion of the inorganic filler such as silica in the rubber composition, the maximum temperature of the rubber composition in the kneading masterbatch kneading stage, particularly the first stage of kneading described later, is 120 to 190. ° C is preferred, 130-175 ° C is more preferred, and 140-170 ° C is even more preferred. The kneading time is preferably 10 seconds to 20 minutes, more preferably 10 seconds to 10 minutes, and further preferably 30 seconds to 5 minutes.

  Further, in the present invention, in the masterbatch kneading stage of kneading, particularly in the first stage of kneading, all of the rubber component (A) and the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent or Even if thioureas are kneaded at the same time as part, the rubber component (A) and the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent are all or partly kneaded, and then thiourea You may add and knead | mix further. After adding all or part of the rubber component (A) and the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent in the kneading masterbatch kneading stage, particularly the first stage of kneading, The time until the thioureas are added during the kneading masterbatch kneading stage is preferably 0 to 180 seconds, and more preferably 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 longer, the rubber composition of the inorganic filler (B) (hereinafter sometimes abbreviated as “inorganic filler (B)”) surface-treated with the sulfur-containing silane coupling agent. Dispersibility in the inside can be further improved. Even if this time exceeds 180 seconds, it is difficult to enjoy further dispersibility improvement effect of the inorganic filler (B) in the rubber composition, and the upper limit is preferably set to 180 seconds.

The kneading step of the rubber composition in the present invention includes at least two stages of a masterbatch kneading stage containing no vulcanizing agent and a final stage of kneading containing the vulcanizing agent. Here, the kneading masterbatch kneading stage refers to the first stage of kneading, the intermediate stage of kneading between the first stage of kneading and the final stage of kneading, and the rubber component (A) and inorganic before the first stage. A kneading step including a step of kneading fillers other than the filler (B). The masterbatch kneading stage of kneading may be only the first stage of kneading.
Here, the first stage of kneading in the present invention refers to the stage of kneading the rubber component (A) and the inorganic filler (B), as long as it is performed prior to the kneading stage including the vulcanizing agent, Before the first stage, the case where the rubber component (A) and the filler other than the inorganic filler (B) are kneaded or the case where only the rubber component (A) is preliminarily kneaded is not included.
However, the masterbatch kneading step includes a step of blending the rubber component (A) and the thiourea before the first step.
Therefore, in the masterbatch kneading stage, mixing the thiourea means that when the rubber component (A) and the thiourea are blended before the first stage of kneading, the rubber component (A) is blended before the first stage of kneading. When blending a filler other than the inorganic filler (B) with thioureas, when blending thioureas at the first stage of kneading, when blending thioureas at the middle stage of kneading, and first stage of kneading And a case where thioureas are blended in a plurality of kneading stages such as both in the middle stage of kneading.
The vulcanizing agent compounded in the final stage of the kneading is a substance capable of cross-linking the polymer chain of the conjugated diene rubber, which is a plastic body, 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.

If it is difficult or desirable to produce a masterbatch with only the first stage of kneading, the kneading masterbatch stage may include an intermediate stage of kneading. In this case, the maximum temperature of the rubber composition in the intermediate stage of kneading is preferably 120 to 190 ° C, more preferably 130 to 175 ° C, and further preferably 140 to 170 ° C. The kneading time is preferably 10 seconds to 20 minutes, more preferably 10 seconds to 10 minutes, and further preferably 30 seconds to 5 minutes. In addition, when including the intermediate stage, after lowering by 10 ° C. or more from the temperature after completion of the kneading in the previous stage, preferably after lowering to room temperature (23 ° C.), more preferably after curing at room temperature, It is desirable to proceed to the next kneading 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 further preferably 100 to 120 ° C. The kneading time is preferably 10 seconds to 20 minutes, more preferably 10 seconds to 10 minutes, and further preferably 20 seconds to 5 minutes.
When proceeding from the kneading masterbatch kneading stage to the final stage, the temperature is lowered by 10 ° C. or more from the temperature after completion of the kneading in the previous stage, preferably lowered to room temperature (23 ° C.), and more preferably at room temperature. It is desirable to proceed to the next kneading stage after curing.
For example, in the kneading masterbatch kneading stage, all or part of the rubber component (A) and the inorganic filler (B) are kneaded in the first kneading stage, for example, after natural cooling and curing, At the stage, thioureas may be added and further kneaded.

The sulfur-containing silane coupling agent used in the production method of the present invention is preferably a compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV).
The rubber composition obtained by the production method of the present invention is more excellent in workability during rubber processing by using the inorganic filler (B) surface-treated with such a sulfur-containing silane coupling agent, and more A tire with good wear resistance can be provided.
Hereinafter, the following general formulas (I) to (IV) will be described in order.

式中、Ｒ¹は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖、環状又は分枝のアルキル基、炭素数２〜８の直鎖又は分枝のアルコキシアルキル基及びシラノール基から選ばれる置換基であり、Ｒ²は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖、環状又は分枝のアルキル基であり、Ｒ³は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖又は分枝のアルキレン基である。ａは平均値として２〜６であり、ｐ及びｒは同一でも異なっていてもよく、各々平均値として０〜３である。但しｐ及びｒの双方が３であることはない。

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 sulfur-containing silane coupling agent represented by the general formula (I) include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (3-methyldimethoxy). Silylpropyl) 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) ) Tetrasulfide, bis (2-monoethoxydimethylsilylethyl) trisulfide, bis (2-monoethoxydimethylsilylethyl) disulfide and the like.

式中、Ｒ⁴は−Ｃｌ、−Ｂｒ、Ｒ⁹Ｏ−、Ｒ⁹Ｃ（＝Ｏ）Ｏ−、Ｒ⁹Ｒ¹⁰Ｃ＝ＮＯ−、Ｒ⁹Ｒ¹⁰ＣＮＯ−、Ｒ⁹Ｒ¹⁰Ｎ−、及び−（ＯＳｉＲ⁹Ｒ¹⁰）_h（ＯＳｉＲ⁹Ｒ¹⁰Ｒ¹¹）から選択される一価の基（Ｒ⁹、Ｒ¹⁰及びＲ¹¹は各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値として１〜４である。）であり、Ｒ⁵はＲ⁴、水素原子又は炭素数１〜１８の一価の炭化水素基であり、Ｒ⁶はＲ⁴、Ｒ⁵、水素原子又は−[Ｏ（Ｒ¹²Ｏ）_j]_0.5 −基（Ｒ¹²は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）であり、Ｒ⁷は炭素数１〜１８の二価の炭化水素基であり、Ｒ⁸は炭素数１〜１８の一価の炭化水素基である。ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。

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 may 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 sulfur-containing silane coupling agent represented by the general formula (II) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, and 3-decanoylthiopropyltriethoxy. Silane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxy Run, 2-octanoylthiopropyl ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane (manufactured by Momentive Performance Materials, trademark “NXT silane”) is particularly preferable.

式中、Ｒ¹³は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖、環状又は分枝のアルキル基、炭素数２〜８の直鎖又は分枝のアルコキシアルキル基及びシラノール基から選ばれる置換基であり、Ｒ¹⁴は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖、環状又は分枝のアルキル基であり、Ｒ¹⁵は複数ある場合には同一でも異なっていてもよく、各々炭素数１〜８の直鎖又は分枝のアルキレン基である。Ｒ¹⁶は一般式
（−Ｓ−Ｒ¹⁷−Ｓ−）、（−Ｒ¹⁸−Ｓ_m1−Ｒ¹⁹−）及び（−Ｒ²⁰−Ｓ_m2−Ｒ²¹−Ｓ_m3−Ｒ²²−）から選ばれる二価の基（Ｒ¹⁷〜Ｒ²²は各々炭素数１〜２０の二価の炭化水素基、二価の芳香族基、並びに硫黄及び酸素以外のヘテロ元素を含む二価の有機基から選ばれる二価の置換基であり、ｍ１、ｍ２及びｍ３は各々平均値として１以上４未満である。）であり、複数あるｋは同一でも異なっていてもよく、各々平均値として１〜６であり、ｓ及びｔは各々平均値として０〜３である。但しｓ及びｔの双方が３であることはない。

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 sulfur-containing silane coupling agent 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 ) ₃ -Si (OCH ₂ CH ₃ ) _{3 and the} like are preferred. The sulfur-containing silane coupling agent 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.

式中、Ｒ²³は炭素数１〜２０の直鎖、分岐又は環状のアルキル基であり、複数あるＧは同一でも異なっていてもよく、各々炭素数１〜９のアルカンジイル基又はアルケンジイル基であり、複数あるＺ^aは同一でも異なっていてもよく、各々二つの珪素原子と結合することのできる官能基であり、かつ [−０−]_0.5、[−０−Ｇ−]_0.5及び[−Ｏ−Ｇ−Ｏ−] _0.5から選ばれる官能基であり、複数あるＺ^bは同一でも異なっていてもよく、各々二つの珪素原子と結合することのできる官能基であり、かつ [−Ｏ−Ｇ−Ｏ−] _0.5で表される官能基であり、複数あるＺ^cは同一でも異なっていてもよく、各々−Ｃｌ、−Ｂｒ、−ＯＲ^e、Ｒ^eＣ(＝Ｏ)Ｏ−、Ｒ^eＲ^fＣ＝ＮＯ−、Ｒ^eＲ^fＮ−、Ｒ^e−及びＨＯ−Ｇ−Ｏ−（Ｇは上記表記と一致する。）から選ばれる官能基であり、Ｒ^e及びＲ^fは各々炭素数１〜２０の直鎖、分岐又は環状のアルキル基である。ｍ、ｎ、ｕ、ｖ及びｗは、１≦ｍ≦２０、０≦ｎ≦２０、０≦ｕ≦３、０≦ｖ≦２、０≦ｗ≦１であり、かつ（ｕ／２）＋ｖ＋２ｗ＝２又は３である。Ａ部が複数である場合、複数のＡ部におけるＺ^a _u、Ｚ^b _v及びＺ^c _wそれぞれにおいて、同一でも異なっていてもよく、Ｂ部が複数である場合、複数のＢ部におけるＺ^a _u、Ｚ^b _v及びＺ^c _wそれぞれにおいて、同一でも異なってもよい。

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 _{[-0-] 0.5, [- 0} -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.

  Specific examples of the sulfur-containing silane coupling agent represented by the general formula (IV) include a trademark “NXT Low-V Silane” manufactured by Momentive Performance Materials, a trademark “NXT UltraSi Low-V Silane”, and a trademark “NXT UltraSi Low-V”. ”, Manufactured by Momentive Performance Materials, trade mark“ NXT-Z ”, and the like.

The sulfur-containing silane coupling agent according to the present invention is particularly preferably a compound represented by the above general formula (I) among the compounds represented by the above general formulas (I) to (IV). This is because thioureas easily cause activation of polysulfide bond sites that react with the rubber component (A).
In this invention, a sulfur containing silane coupling agent may be used individually by 1 type, and may be used in combination of 2 or more type.

The surface treatment method of the inorganic filler (B) used in the production method of the present invention is not limited. For example, a predetermined amount of a silane coupling agent is supported on the dry treatment method, wet treatment method, or inorganic filler in advance. Things can be used.
Examples of the dry processing method include a method in which a predetermined amount of a sulfur-containing silane coupling agent is mixed with an inorganic filler such as silica, and the mixture is stirred with a mixer or the like, and heat-treated at about 100 to 170 ° C. as necessary.
In addition, the wet processing method includes adding and mixing an inorganic filler such as silica in a solution in which a sulfur-containing silane coupling agent is dispersed or dissolved to form a slurry, and then heating and stirring as necessary, followed by drying. A method for obtaining surface-treated silica is mentioned.

As a method of surface treatment of the inorganic filler, it is preferable to carry out by a dry treatment method using a mixer such as a Henschel mixer. For example, by putting a pre-dried inorganic filler such as silica in a preheated mixer, applying the treatment liquid to the inorganic filler such as silica by spraying or dripping while stirring, and after stirring for a predetermined time Surface treatment can be performed.
In the case of the dry treatment method, it is preferable to use an inorganic filler such as silica that has been dried in advance. In particular, silica adsorbs moisture in the air due to the presence of silanol groups on the particle surface. However, when the amount of adsorbed water is large, the silica tends to aggregate. Therefore, the silica is pre-dried to reduce adsorbed water, thereby reducing the cohesive force of silica and increasing the crushing effect by the mixer during the surface treatment. Moreover, by reducing the amount of adsorbed water, the reaction between the silica and the sulfur-containing silane coupling agent can be made uniform, and the influence on the surface treatment due to the seasonal variation in the amount of adsorbed water can be reduced. The conditions for preliminary drying of the inorganic filler such as silica are not particularly limited, and for example, heating can be performed at 100 to 140 ° C. for 30 minutes to 3 hours.

  The amount of the sulfur-containing sulfur-containing silane coupling agent used in the surface treatment is preferably 1 to 20 parts by weight, more preferably 2 to 20 parts by weight with respect to 100 parts by weight of an inorganic filler such as silica. 3 to 15 parts by weight is more preferable, and 4 to 15 parts by weight is particularly preferable. If the amount of the sulfur-containing sulfur-containing silane coupling agent used is too small, the dispersibility and reinforcing effect when blended into the rubber composition may not be satisfied. Conversely, if the amount used is too large, the cost is high and uneconomical.

  In the present invention, it is preferable to perform heat drying after the surface treatment. By post-drying, the reaction between the inorganic filler such as silica and the sulfur-containing sulfur-containing silane coupling agent can be completed. That is, the reaction between the inorganic filler such as silica and the sulfur-containing sulfur-containing silane coupling agent may not be sufficient if the treatment is performed with stirring in a mixer such as a Henschel mixer. Moreover, it is preferable to perform heat drying after the treatment. Moreover, the carboxylic acid as an acidic compound can be evaporated and removed by this heat drying. In addition, as heat drying conditions, it can carry out at 100-150 degreeC for 30 minutes-3 hours, for example. Moreover, it is preferable to ventilate during heat drying, and can accelerate | stimulate reaction.

  Subsequent to the above surface treatment, if necessary, it may be further treated with a hydrophobizing agent. This is because the dispersibility of the inorganic filler such as silica in the rubber component (A) is further enhanced. Examples of the hydrophobizing agent include fatty acids having 5 to 30 carbon atoms and derivatives thereof, modified liquid polymers, higher alcohols and glycidyl ethers thereof, polyethers, and the like. Two or more types can be used in combination. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, and may have a linear structure or a branched structure. Specific examples include hexanoic acid, decanoic acid, dodecanoic acid, myristic acid, isomyristic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, oleic acid, and behenylic acid. It can be used alone or in combination of two or more.

  Synthetic diene rubbers of the rubber component (A) used in the production method of the present invention include styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), acrylonitrile-butadiene copolymer. Combined rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Cl-IIR, Br-IIR, etc.), ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-butadiene copolymer rubber (EBR) Propylene-butadiene copolymer rubber (PBR) or the like can be used, and natural rubber and synthetic diene rubber may be used singly or as a blend of two or more.

As the inorganic filler used in the inorganic filler (B) according to the production method of the present invention, silica and an inorganic compound represented by the following general formula (V) can be used.
dM ¹ · xSiO _y · zH ₂ O (V)
Here, in the general formula (V), 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 (V), 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.

In the present invention, among the inorganic fillers used for the above-mentioned inorganic filler (B), silica is preferable from the viewpoint of achieving both low rolling properties and wear resistance. Any commercially available silica can be used. Among these, wet precipitation silica, wet gelation silica, dry silica, and colloidal silica are preferably used, and wet precipitation silica is particularly preferable. 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 “Nipsil AQ” (BET specific surface area = 205 m ² / g), “Nipsil KQ”, Degussa product name “Ultrasil VN3” (BET specific surface area = 175 m). ² / g) can be used.

As the inorganic compound represented by the general formula (V), .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 (IX) 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 (V) may be used alone or in combination of two or more. The average particle size of these inorganic compounds is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 5 μm, from the viewpoints of kneading workability, wear resistance, and wet grip performance balance.
The inorganic filler used in the inorganic filler (B) in the present invention may be silica alone, or may be used in combination with silica and one or more inorganic compounds represented by the general formula (V). .

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.

The inorganic filler (B) used in the production method 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.
Moreover, it is preferable to use 20-150 mass parts of fillers of the rubber composition which concerns on this invention with respect to 100 mass parts of rubber components (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 surface treatment silica as an inorganic filler (B), it is preferable that the surface treatment silica in the said filler is 30 mass% or more.

In the production method of the present invention, various compounding agents such as vulcanization activators such as stearic acid, resin acid, zinc white, and anti-aging agents, which are usually compounded in the rubber composition, are optionally the first stage of kneading. Alternatively, they are kneaded in the final stage or in an 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 internal mixer, a roll, an intensive mixer, a kneader, a twin screw extruder, or the like is used.

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%. As an index by the following formula. A smaller index value indicates a lower exothermic property and a smaller hysteresis loss.
Low exothermic index = {(tan δ of test vulcanized rubber composition) / (tan δ of vulcanized rubber composition of Comparative Example 1)} × 100

Abrasion resistance (index)
In accordance with JIS K 6264-2: 2005, using a Lambone-type wear tester, a test was performed at room temperature under the condition of a slip rate of 25%, and the reciprocal of the wear amount was set to the following formula with the value of Comparative Example 1 being 100. Indexed. The larger the value, the better the wear resistance.
Abrasion resistance index = {(Abrasion amount of vulcanized rubber composition of Comparative Example 1) / (Abrasion amount of test vulcanized rubber composition)} × 100

Production Example 1
In a Henschel mixer preheated to 100 ° C., 1000 g of silica manufactured by Tosoh Silica Co., Ltd., trade name “Nipsil AQ” (BET specific surface area = 205 m ² / g) is added and stirred, and 100 g of a sulfur-containing silane coupling agent { Bis (3-triethoxysilylpropyl) disulfide (average sulfur chain length: 2.35), manufactured by Evonik Dexa, trade name “Si75” (registered trademark)} was sprayed. Stirring was continued for 20 minutes and the temperature was raised to 120 ° C. Stirring was further continued for 30 minutes to obtain surface-treated silica A.

Production Example 2
In a Henschel mixer preheated to 100 ° C., 1000 g of silica manufactured by Tosoh Silica Co., Ltd., trade name “Nipsil AQ” (BET specific surface area = 205 m ² / g) is added and stirred, and 80 g of a sulfur-containing silane coupling agent { Bis (3-triethoxysilylpropyl) disulfide (average sulfur chain length: 2.35), manufactured by Evonik Dexa, trade name “Si75” (registered trademark)} was sprayed. Stirring was continued for 20 minutes and the temperature was raised to 120 ° C. Stirring was further continued for 30 minutes to obtain surface-treated silica B.

Examples 1 to 4, Reference Examples 1 to 2 and Comparative Example 1
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 160 ° C. and kneaded with a Banbury mixer to prepare seven types of rubber compositions. did. In the first stage of kneading the rubber compositions of Examples 1 to 4 and Reference Examples 1 to 2 , all of the rubber component (A) and the inorganic filler (B) surface-treated with the sulfur-containing silane coupling agent were added. After kneading for 30 seconds, thioureas were added and further kneaded. In the first stage of kneading the rubber composition of Comparative Example 1, kneading was carried out in the same manner as the rubber composition of Example 1 except that none of the thioureas was added. The resulting unvulcanized rubber composition was vulcanized at a temperature of 165 ° C., and the vulcanization time was defined as t _c (90) value (min) × 1.5 times {specified in JIS K 6300-2: 2001 T _c (90) value}. The low exothermic property (tan δ index) and the wear resistance (index) of the 7 kinds of vulcanized rubber compositions obtained were evaluated by the above methods. The results are shown in Table 1.

[note]
* 1: Asahi Kasei Corporation, solution polymerization SBR, trade name “Toughden 2000”
* 2: Asahi Carbon Co., Ltd., trade name “# 80”
* 3: Surface-treated silica A obtained in Production Example 1
* 4: Surface-treated silica B obtained in Production Example 2
* 5: Thiourea, manufactured by Sakai Chemical Industry Co., Ltd., trade name “thiourea”)
* 6: N, N'-dibutylthiourea, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sunseller BUR"
* 7: N, N'-diphenylthiourea, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name "Noxeller C"
* 8: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 6C”
* 9: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 224”
* 10: 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller D”
* 11: Di-2-benzothiazolyl disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller DM”
* 12: N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Suncellor NS”

As is clear from Table 1 , the rubber compositions of Examples 1 to 4 and Reference Examples 1 to 2 all have low heat build-up (tan δ index) compared to the rubber composition of Comparative Example 1. there were. In addition, the rubber compositions of Examples 1 to 4 gave good results in terms of wear resistance in addition to low exothermic properties.

  The method for producing a rubber composition of the present invention can provide a rubber composition excellent in low heat build-up, so that it can be used for passenger cars, small trucks, light passenger cars, light trucks and large vehicles {for trucks and buses. , For off-the-road tires (for construction vehicles, mining vehicles, etc.)} and the like, particularly as a method for producing tread members (particularly tread grounding member) for pneumatic radial tires. .

Claims (5)

A rubber component (A) comprising at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B) surface-treated by a dry treatment method with a sulfur-containing silane coupling agent, and thiourea A method for producing a rubber composition comprising blending, wherein the rubber composition is kneaded in a plurality of stages including a masterbatch kneading stage, and the rubber component (A) and the inorganic filler ( A method for producing a rubber composition, comprising kneading all or part of B) and the thiourea.   The method for producing a rubber composition according to claim 1, wherein the maximum temperature of the rubber composition in the masterbatch kneading step is 120 to 190 ° C. The method for producing a rubber composition according to claim 1 or 2, wherein the sulfur-containing silane coupling agent is a compound selected from the group consisting of compounds represented by the following general formulas (I) to (IV). .

(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, a linear or branched alkyl group having 2 to 8 carbon atoms. A substituent selected from an alkoxyalkyl 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, When there are a plurality of R ^{3 s} , they may be the same or different 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 are the same However, they may be different, and each is an average value of 0 to 3. However, both p and r are not 3.)

{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 carbon atom having 1 to 18 carbon atoms. H is an average value of 1 to 4), R ⁵ is R ⁴ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ⁶ is R ⁴ , R ⁵ , a hydrogen atom, or — [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 divalent hydrocarbon group having 1 to 18 carbon atoms, 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 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, a linear or branched alkyl group having 2 to 8 carbon atoms. A substituent selected from an alkoxyalkyl 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 R ^{15 s} , 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 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. }

{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. , and the 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 _{[-0-] 0.5, [- 0} -G-] 0 _.5 and [—O—G—O—] _0.5 is a functional group selected from _0.5 , and a plurality of Z ^b may be the same or different and each is a functional group capable of bonding to two silicon atoms. And a functional group represented by [—O—G—O—] _0.5 , 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 is a functional group selected from.) Matching the above notation, 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, and when there are a plurality of B parts, Z ^a in ^a plurality of B parts Each of _u , Z ^b _v and Z ^c _w may be the same or different. }   The method for producing a rubber composition according to claim 3, wherein the sulfur-containing silane coupling agent is a compound represented by the general formula (I).   The method for producing a rubber composition according to any one of claims 1 to 4, wherein the inorganic filler (B) is silica.