JP5592219B2 - 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.

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, reduction of rolling resistance is also demanded for tire performance. Conventionally, as a technique for reducing the rolling resistance of a tire, a technique for optimizing the tire structure has been studied, but it is currently most important to use a rubber composition having a lower exothermic property as a rubber composition applied to the tire. This is done as a general method.
As a method for obtaining such a rubber composition having low exothermicity, a method using an inorganic filler such as silica as a filler is known.
However, when an inorganic filler such as silica is blended in an inorganic filler-containing rubber composition, the inorganic filler, especially silica, aggregates in the rubber composition (caused by hydroxyl groups on the silica surface). Therefore, a silane coupling agent is used to prevent aggregation.
Therefore, various attempts have been made in order to improve the activity of the coupling function of the silane coupling agent in order to suitably solve the above problems by blending the silane coupling agent.

For example, in Patent Document 1, 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 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). A rubber composition comprising an alkoxysilane together with (iv) zinc dithiophosphate and (v) a guanidine derivative is disclosed.
Patent Document 3 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 4, 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.
However, in these inventions, the kneading conditions have not been considered.
In addition, as an example of enhancing the activity of the coupling function of the silane coupling agent in consideration of the kneading conditions, Patent Document 5 can be cited, but the effect of enhancing the activity of the coupling function of the silane coupling agent is other compounding. No consideration has been made to suppress the reduction by the agent.

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, the present invention suitably suppresses the activity reduction of the coupling function of the silane coupling agent, further increases the activity of the coupling function, and obtains a rubber composition that preferably has a low heat generation. It is an object of the present invention to provide a method for producing a rubber composition that can be used.

In order to solve the above-mentioned problems, the present inventors, in the first stage of the kneading process, the rubber component, all or part of the inorganic filler, all or part of the silane coupling agent, guanidines, As a result of blending with at least one vulcanization accelerator selected from sulfenamides and thiazoles and conducting various experiments, at least one vulcanization acceleration selected from guanidines, sulfenamides and thiazoles was obtained. It has been found that there are cases where the effect of enhancing the activity of the coupling function is high and low even when an agent is blended. As a result of various experimental analyzes of factors that enhance the effect, the amount of the organic acid compound and guanidines, sulfenamides, and thiazoles are selected in order to increase the activity of the coupling function. The present invention has been completed by experimentally discovering that the blending amount of at least one vulcanization accelerator should be in a specific relationship.
That is, the present invention relates to a rubber component (A) composed of at least one selected from natural rubber and synthetic diene rubber, a filler containing an inorganic filler (B), and a silane cup represented by the following general formula (1). A method for producing a rubber composition comprising a ring agent (C) and at least one vulcanization accelerator (D) selected from guanidines, sulfenamides and thiazoles, wherein the rubber composition is divided into a plurality of stages. In the first stage of kneading, all or part of the rubber component (A), the inorganic filler (B), all or part of the silane coupling agent (C) and the vulcanization accelerator (D ), And the molecular number X of the organic acid compound (E) in the rubber composition in the first step is represented by the following formula (2) with respect to the molecular number Y of the vulcanization accelerator (D): It is a manufacturing method of the rubber composition characterized by having a relationship.

｛式中、Ｒ¹は炭素数１〜２０の直鎖、分岐又は環状のアルキル基であり、Ｇは同一でも異なっていても良く、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、Ｚ^aは同一でも異なっていても良く、各々二つの珪素原子と結合することのできる基で、且つ [−Ｏ−]_0.5、[−Ｏ−Ｇ−]_0.5又は[−Ｏ−Ｇ−Ｏ−] _0.5から選ばれる基であり、Ｚ^bは同一でも異なっていても良く、各々二つの珪素原子と結合することのできる基で、且つ [−Ｏ−Ｇ−Ｏ−] _0.5で表される官能基であり、Ｚ^cは同一でも異なっていても良く、各々−Ｃｌ、−Ｂｒ、−ＯＲ^a、Ｒ^aＣ(＝Ｏ)Ｏ−、Ｒ^aＲ^bＣ＝ＮＯ−、Ｒ^aＲ^bＮ−、Ｒ^a−、ＨＯ−Ｇ−Ｏ−（Ｇは上記表記と一致する。）で表される官能基であり、Ｒ^a及びＲ^bは同一でも異なっていても良く、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、ｗは同一でも異なっていても良く、１≦ｍ≦２０、０≦ｎ≦２０、０≦ｕ≦３、０≦ｖ≦２、０≦ｗ≦１であり、且つ（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良く、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良い。｝
０≦Ｘ≦１．５×Ｙ ・・・（２）

{In the formula, R ¹ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and G may be the same or different and each is an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms. , Z ^a may be the same or different, a group capable of binding with each of two silicon atoms, and _{[- O -] 0.5, [} - O -G-] 0.5 or [-O-G-O -] Is a group selected from _0.5 , Z ^b may be the same or different, each being a group capable of bonding to two silicon atoms, and represented by [—O—G—O—] _0.5 A functional group, Z ^c may be the same or different and each represents —Cl, —Br, —OR ^a , R ^a C (═O) O—, R ^a R ^b C═NO—, R ^a R ^{b N-, R a -, HO-} G-O- (. G is consistent with the notation) is a functional group represented by, R ^a and R ^b be the same or different Well, they are each straight-chain, branched or cyclic alkyl group having 1 to 20 carbon atoms. m, n, u, v, and w may be the same or different, and 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 ^a plurality of B parts Each of _u , Z ^b _v and Z ^c _w may be the same or different. }
0 ≦ X ≦ 1.5 × Y (2)

  According to the present invention, it is possible to suitably suppress a reduction in the activity of the coupling function of the silane coupling agent (C), to further increase the activity of the coupling function, and to obtain a rubber composition excellent in low heat generation. The manufacturing method of the rubber composition which is can be provided.

It is a graph which shows the critical regression type of Formula (2) concerning the present invention. X is the number of molecules of the organic acid compound (E) in the rubber composition in the first stage of kneading, and Y is the number of molecules of the vulcanization accelerator (D) in the rubber composition.

The present invention is described in detail below.
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 the general formula (1). A rubber composition comprising a silane coupling agent (C) and at least one vulcanization accelerator (D) selected from guanidines, sulfenamides and thiazoles, the rubber composition comprising: In a first stage of kneading, the rubber component (A), all or part of the inorganic filler (B), all or part of the silane coupling agent (C) and The sulfur accelerator (D) is added and kneaded, and the molecular number X of the organic acid compound (E) in the rubber composition in the first stage is as follows with respect to the molecular number Y of the vulcanization accelerator (D) It has the relationship of Formula (2).
0 ≦ X ≦ 1.5 × Y (2)
In the present invention, the vulcanization accelerator (D) is added and kneaded in the first stage of kneading in order to increase the activity of the coupling function of the silane coupling agent (C). The vulcanization accelerator is that the number of molecules (number of moles) X of the organic acid compound (E) in the rubber composition is 1.5 times or less the number of molecules (number of moles) Y of the vulcanization accelerator (D). (D) It is for suppressing suitably that the activity improvement effect of the coupling function by a mixing | blending reduces.

  In order to more suitably increase the activity of the coupling function of the silane coupling agent (C), the maximum temperature of the rubber composition in the first stage of kneading is preferably 120 to 190 ° C, More preferably, it is 175 degreeC, and it is further more preferable that it is 140-170 degreeC.

The rubber composition kneading step in the present invention includes at least two stages of a first stage of kneading that does not include other vulcanizing agents other than the vulcanization accelerator (D) and a final stage of kneading that includes the vulcanizing agent and the like. It includes a stage, and may include an intermediate stage of kneading that does not include other vulcanizing agents other than the vulcanization accelerator (D), if necessary. Here, vulcanizing agents and the like refer to vulcanizing agents and vulcanization accelerators.
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). A stage in the case of kneading A) and a filler other than the inorganic filler (B) or in the case of preliminarily kneading only the rubber component (A) is not included.

[Silane coupling agent (C)]
The silane coupling agent (C) used in the method for producing a rubber composition of the present invention comprises a compound represented by the above general formula (1) and is represented by any one of the following chemical formulas (3) to (5). A compound is preferred.

式中、Ｌはそれぞれ独立して炭素数１〜９のアルカンジイル基又はアルケンジイル基であり、ｘ＝ｍ、ｙ＝ｎである。ここで、ｍ及びｎは、上記一般式（１）におけるｍ及びｎである。

In the formula, each L is independently an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms, and x = m and y = n. Here, m and n are m and n in the general formula (1).

As the silane coupling agent represented by the chemical formula (3), a trademark “NXT Low-V Silane” manufactured by Momentive Performance Materials is commercially available.
Moreover, as a silane coupling agent represented by Chemical formula (4), the trademark "NXT Ultra Low-V Silane" manufactured by Momentive Performance Materials is also available as a commercial product.
Furthermore, examples of the silane coupling agent represented by the chemical formula (5) include “NXT-Z” manufactured by Momentive Performance Materials.
Since the silane coupling agent obtained by the chemical formulas (3), (4) and (5) has a large number of alkoxysilane carbon atoms, the generation of a volatile compound VOC (especially alcohol) is small, which is preferable in the working environment, and is less exothermic A good pneumatic tire can be provided.
Further, the silane coupling agent represented by the chemical formula (5) is preferable because it can provide further low heat generation as tire performance.

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.
It is preferable that the compounding quantity of the silane coupling agent (C) of the rubber composition which concerns on this invention is 1-20 mass% of an inorganic filler. If the amount is less than 1% by mass, the effect of improving the low heat build-up of the rubber composition is hardly exhibited. If the amount exceeds 20% by mass, the cost of the rubber composition becomes excessive and the economic efficiency is lowered. Furthermore, it is more preferable that it is 3-20 mass% of an inorganic filler, and it is especially preferable that it is 4-10 mass% of an inorganic filler.

[Vulcanization accelerator (D)]
Examples of the vulcanization accelerator (D) used in the method for producing the rubber composition of the present invention include guanidines, sulfenamides, and thiazoles.
Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, dicatechol borate di-o-tolylguanidine salt, 1,3-di-o- Examples include cumenyl guanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionyl guanidine, and the like. 1,3-diphenyl guanidine, 1,3-di-o-tolyl Guanidine and 1-o-tolylbiguanide are more preferable because of their high reactivity, and 1,3-diphenylguanidine is particularly preferable because of its higher reactivity.
Examples of the sulfenamides include N-oxydiethylene-2-benzothiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-2-benzothiazolylsulfenamide and N -Tert-butyl-2-benzothiazolylsulfenamide and the like, and N-cyclohexyl-2-benzothiazolylsulfenamide and N-tert-butyl-2-benzothiazolylsulfenamide are highly reactive It is more preferable.
Examples of thiazoles include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, 2-mercaptobenzothiazolecyclohexylamine salt, 2-mercaptobenzothiazole sodium salt, 2 (4-mol For example, di-2-benzothiazolyl disulfide and 2-mercaptobenzothiazole are more preferable because of high reactivity.

  In the first stage of kneading according to the present invention, the number of molecules (number of moles) of the vulcanization accelerator (D) is 0.1 to 1.0 times the number of molecules (number of moles) of the silane coupling agent (C). Preferably there is. This is because the activation of the silane coupling agent (C) occurs sufficiently when the ratio is 0.1 times or more, and the vulcanization speed is not greatly affected when the ratio is 1.0 times or less. More preferably, the number of molecules (number of moles) of the vulcanization accelerator (D) is 0.3 to 1.0 times the number of molecules (number of moles) of the silane coupling agent (C).

Furthermore, as a method for charging the vulcanization accelerator (D) in the first stage, all or part of the rubber component (A), the inorganic filler (B) and all or part of the silane coupling agent (C) are used. It is preferable to add the vulcanization accelerator (D) after kneading and further knead. This is because, by this charging method, the reaction between the silane coupling agent (C) and the rubber component (A) can be advanced after the reaction between the silane coupling agent (C) and the silica has sufficiently progressed.
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 It is preferable that the time until the vulcanization accelerator (D) is added during the process is 10 to 180 seconds. The lower limit value of this time is more preferably 30 seconds or more, and the upper limit value is more preferably 150 seconds or less, and still more 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.

Moreover, it is preferable that the number of molecules of the vulcanization accelerator (D) in the rubber composition in the first stage of kneading is 0.1 to 1 times the number of molecules of the silane coupling agent (C). This is because the activation of the silane coupling agent (C) is sufficiently achieved when it is 0.1 times or more, and the vulcanization rate is not greatly affected when it is 1 or less. More preferably, the number of molecules (number of moles) of the vulcanization accelerator (D) is 0.4 to 1.0 times the number of molecules (number of moles) of the silane coupling agent (C).
Since the vulcanization accelerator (D) is also used as a sulfur vulcanization accelerator, an appropriate amount may be blended as desired even in the final stage of kneading.

[Organic acid compound]
Examples of the organic acid compound in the present invention include stearic acid, palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, capric acid, pelargonic acid, caprylic acid, enanthic acid, caproic acid, oleic acid, vaccenic acid Organic acids such as saturated fatty acids and unsaturated fatty acids such as linoleic acid, linolenic acid and nervonic acid, and resin acids such as rosin acid and modified rosin acid, alkali metal salts or esters of the saturated fatty acids and unsaturated fatty acids and resin acids Etc. As the alkali metal, sodium, potassium and the like are preferable.
In the present invention, 50 mol% or more in the organic acid compound is preferably stearic acid because it is necessary to sufficiently exhibit the function as a vulcanization acceleration aid.
Further, when an emulsion-polymerized styrene-butadiene copolymer is used as a part or all of the rubber component (A), rosin acid (50 mol% or more in the organic acid compound is contained in the emulsion-polymerized styrene-butadiene copolymer ( Modified rosin acid is also included) and / or a fatty acid is preferable from the viewpoint of an emulsifier necessary for polymerizing an emulsion-polymerized styrene-butadiene copolymer.

[Rubber component (A)]
Synthetic diene rubbers of the rubber component (A) used in the method for producing a rubber composition of the present invention include styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), butyl rubber. (IIR), ethylene-propylene-diene terpolymer rubber (EPDM) and 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 (B) used in the method for producing a rubber composition of the present invention, silica and an inorganic compound represented by the following general formula (6) can be used.
dM ¹ · xSiO _y · zH ₂ O (6)
Here, in the general formula (6), M ¹ is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium, and zirconium, an oxide or hydroxide of these metals, and a hydrate 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 (6), 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 (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 silicas are those manufactured by Tosoh Silica Co., Ltd., trade names “Nipsil AQ” (BET specific surface area = 220 m ² / g), “Nipsil KQ”, and Degussa's trade name “Ultra Gil VN3” (BET specific surface area = 175 m ^2. / G) and other commercial products can be used.

As the inorganic compound represented by the general formula (6), .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 (6) 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 (6) 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 (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 (6).

The filler of the rubber composition according to 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).

The inorganic filler (B) of the rubber composition according to 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 40% by mass or more from the viewpoint of achieving both wet performance and rolling resistance, and more preferably 70% by mass or more.

In the method for producing a rubber composition of the present invention, usually, various compounding agents such as a vulcanization activator such as zinc white and an anti-aging agent blended in the rubber composition are used in the first stage or final stage of kneading as required. It is kneaded in a stage or 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 roll, an intensive mixer 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) was evaluated by the following method.

Low exothermicity (tan δ index)
Using a viscoelasticity measuring device (Rheometrics), tan δ was measured at a temperature of 60 ° C., a strain of 5%, and a frequency of 15 Hz. The reciprocal of tan δ of the reference vulcanized rubber composition was taken as 100 and expressed as an index using the following formula. A larger index value indicates a lower exothermic property and a smaller hysteresis loss.
Low exothermic index = {(tan δ of reference vulcanized rubber composition) / (tan δ of test vulcanized rubber composition)} × 100

Examples 1-24 and Comparative Examples 1-31
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 55 types of rubber compositions. did. In the first stage of kneading all the rubber compositions other than Comparative Examples 1 and 2, vulcanization is accelerated after kneading all of the rubber component (A), the inorganic filler (B), and the silane coupling agent (C). 1,3-Diphenylguanidine, which is a guanidine, was added as an agent (D) and further kneaded. The low exothermic properties (tan δ index) of the 55 types of rubber compositions obtained were evaluated by the above methods. The results are shown in Table 1.

[note]
* 1: Emulsion polymerization SBR manufactured by JSR Corporation, trade name “# 1500”
* 2: Asahi Kasei Corporation, solution polymerization SBR, trade name “Toughden 2000”
* 3: Asahi Carbon Co., Ltd., trade name “# 80”
* 4: Tosoh Silica Co., Ltd., nip seal AQ, BET surface area 220 m ² / g
* 5: Silane coupling agent represented by the above chemical formula (5), manufactured by Momentive Performance Materials, trade name “NXT-Z” (registered trademark)
* 6: 3-octanoylthiopropyltriethoxysilane, manufactured by Momentive Performance Materials, trade name “NXT silane” (registered trademark)
* 7: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 6C”
* 8: 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller D”
* 9: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 224”
* 10: Di-2-benzothiazolyl disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Sunseller DM”
* 11: N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name “Suncellor NS”
* 12: Silane coupling agent represented by the above chemical formula (3), manufactured by Momentive Performance Materials, trade name “NXT Low-V Silane” (registered trademark)
* 13: Silane coupling agent represented by the above chemical formula (4), manufactured by Momentive Performance Materials, trade name “NXT Ultra Low-V Silane” (registered trademark)

Examples 25-28 and Comparative Example 32
Next, 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. A product was prepared. In the first stage of kneading all the rubber compositions, after kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), guanidines are used as the vulcanization accelerator (D). 1,3-diphenylguanidine was added and further kneaded. The low exothermic properties (tan δ index) of the five types of rubber compositions obtained were evaluated by the above methods. The results are shown in Table 2. For comparison, Examples 1 and 6 and Comparative Examples 1 and 3 are shown again.

［注］＊１〜＊１３のいずれも第１表と同じである。

[Note] * 1 to * 13 are the same as those in Table 1.

Examples 29 and 30 and Comparative Examples 33 and 34
Six types of rubber compositions were prepared by kneading with a Banbury mixer according to the formulation and kneading method shown in Table 3. Four types of rubber compositions were prepared by adjusting the maximum temperature of the rubber composition in the first stage of kneading to 150 ° C. and kneading with a Banbury mixer. In the first stage of kneading all the rubber compositions, after kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), guanidines are used as the vulcanization accelerator (D). 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine or 1-o-tolylbiguanide was added and further kneaded. The low exothermic properties (tan δ index) of the four types of rubber compositions obtained were evaluated by the above methods. The results are shown in Table 3. For comparison, Example 1 and Comparative Examples 2 and 3 are shown again.

［注］
＊１〜＊１３のいずれも第１表と同じである。
＊１４： 大内新興化学工業株式会社製、商品名「ノクセラーＤＴ」
＊１５： 大内新興化学工業株式会社製、商品名「ノクセラーＢＧ」

[note]
* 1 to * 13 are the same as those in Table 1.
* 14: Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller DT”
* 15: Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller BG”

Examples 31-54 and Comparative Examples 35-47
According to the formulation and kneading method shown in Table 4, 37 types of rubber compositions were prepared by adjusting the maximum temperature of the rubber composition in the first stage of kneading to 150 ° C. and kneading with a Banbury mixer. did. In the first stage of kneading all the rubber compositions, after kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), sulfene is used as the vulcanization accelerator (D). N-cyclohexyl-2-benzothiazolylsulfenamide, which is an amide, was added and further kneaded. The low exothermic properties (tan δ index) of the 37 kinds of rubber compositions obtained were evaluated by the above methods. The results are shown in Table 4. For comparison, Comparative Examples 1 and 2 are shown again.

[note]
* 1 to * 13 are the same as those in Table 1.
* 16: Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller CZ”

Examples 55-59 and Comparative Examples 48-50
Next, according to the formulation and kneading method shown in Table 5 or Table 6, the maximum temperature of the rubber composition in the first stage of kneading is adjusted to 150 ° C. and kneaded with a Banbury mixer. A variety of rubber compositions were prepared. In the first stage of kneading all the rubber compositions, after kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), sulfene is used as the vulcanization accelerator (D). N-cyclohexyl-2-benzothiazolylsulfenamide or N-tert-butyl-2-benzothiazolylsulfenamide, which is an amide, was added and further kneaded. The low exothermic properties (tan δ index) of the eight types of rubber compositions obtained were evaluated by the above methods. The results are shown in Tables 5 and 6. For comparison, Examples 31 and 36 and Comparative Example 1 are shown again in Table 5, and Example 31 and Comparative Examples 2 and 48 are shown again in Table 6.

［注］
＊１〜＊１３のいずれも第１表と同じであり、＊１６は第４表と同じである。

[note]
* 1 to * 13 are the same as those in Table 1, and * 16 are the same as those in Table 4.

［注］
＊１〜＊１３のいずれも第１表と同じであり、＊１６は第４表と同じである。

[note]
* 1 to * 13 are the same as those in Table 1, and * 16 are the same as those in Table 4.

Examples 60-83 and Comparative Examples 51-63
According to the formulation and kneading method shown in Table 7, 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 36 types of rubber compositions. did. In the first stage of kneading all the rubber compositions, after thorough kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), thiazoles as a vulcanization accelerator (D) 2-mercaptobenzothiazole was added and further kneaded. The low exothermic properties (tan δ index) of the 36 types of rubber compositions obtained were evaluated by the above methods. The results are shown in Table 7. For comparison, Comparative Examples 1 and 2 are shown again.

＊１〜＊１３のいずれも第１表と同じである。
＊１７： 大内新興化学工業株式会社製、商品名「ノクセラーＭ」

* 1 to * 13 are the same as those in Table 1.
* 17: Product name “Noxeller M” manufactured by Ouchi Shinsei Chemical Co., Ltd.

[note]
* 1 to * 13 are the same as those in Table 1, and * 17 are the same as those in Table 9.

Examples 84-88 and Comparative Examples 64-66
Next, according to the formulation and kneading method shown in Table 8 or Table 9, the maximum temperature of the rubber composition in the first stage of kneading is adjusted to 150 ° C. and kneaded with a Banbury mixer. A variety of rubber compositions were prepared. In the first stage of kneading all the rubber compositions, after thorough kneading all of the rubber component (A), the inorganic filler (B) and the silane coupling agent (C), thiazoles as a vulcanization accelerator (D) 2-Mercaptobenzothiazole or di-2-benzothiazolyl disulfide was added and further kneaded. The low exothermic properties (tan δ index) of the five types of rubber compositions obtained were evaluated by the above methods. The results are shown in Tables 8 and 9. For comparison, Comparative Example 1 is shown again in Table 8, and Examples 60 and 84 and Comparative Examples 2 and 34 are shown again in Table 9.

［注］
＊１〜＊１３のいずれも第１表と同じである。

[note]
* 1 to * 13 are the same as those in Table 1.

［注］
＊１〜＊１３のいずれも第１表と同じであり、＊１７は第９表と同じである。
＊＊： ジ−２−ベンゾチアゾリルジスルフィドが分解して発生するチアゾールの分子数

[note]
* 1 to * 13 are the same as those in Table 1, and * 17 are the same as those in Table 9.
**: Number of thiazole molecules generated by decomposition of di-2-benzothiazolyl disulfide

The critical regression equation according to the present invention was obtained by plotting Examples 1 to 88 and Comparative Examples 1 to 66 on a graph. FIG. 1 shows the obtained critical regression equation of the equation [1] according to the present invention.
As is apparent from Tables 1 to 9 and FIG. 1, the rubber compositions of Examples 1 to 88 are all less heat-generating (tan δ) than the rubber compositions to be compared in Comparative Examples 1 to 66. Index) was good.

  The method for producing a rubber composition of the present invention suitably suppresses the activity reduction of the coupling function of the silane coupling agent, further increases the activity of the coupling function, and obtains a rubber composition excellent in low heat buildup. Can be used for various pneumatic tire components such as passenger cars, small trucks, light passenger cars, light trucks and large vehicles (trucks, buses, construction vehicles, etc.), especially pneumatic treads for pneumatic radial tires. It is suitably used as a method for manufacturing a member for use.

Claims (12)

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) represented by the following general formula (1), and A method for producing a rubber composition comprising at least one vulcanization accelerator (D) selected from guanidines, sulfenamides and thiazoles, wherein the rubber composition is kneaded in a plurality of stages, In one step, the rubber component (A), all or part of the inorganic filler (B), all or part of the silane coupling agent (C) and the vulcanization accelerator (D) are added and kneaded. In addition, the molecular number X of the organic acid compound (E) in the rubber composition in the first stage is in the relationship of the following formula (2) with respect to the molecular number Y of the vulcanization accelerator (D). A method for producing a rubber composition.

{In the formula, R ¹ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and G may be the same or different and each is an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms. , Z ^a may be the same or different, a group capable of binding with each of two silicon atoms, and _{[- O -] 0.5, [} - O -G-] 0.5 or [-O-G-O -] Is a group selected from _0.5 , Z ^b may be the same or different, each being a group capable of bonding to two silicon atoms, and represented by [—O—G—O—] _0.5 A functional group, Z ^c may be the same or different and each represents —Cl, —Br, —OR ^a , R ^a C (═O) O—, R ^a R ^b C═NO—, R ^a R ^{b N-, R a -, HO-} G-O- (. G is consistent with the notation) is a functional group represented by, R ^a and R ^b be the same or different Well, they are each straight-chain, branched or cyclic alkyl group having 1 to 20 carbon atoms. m, n, u, v, and w may be the same or different, and 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 ^a plurality of B parts Each of _u , Z ^b _v and Z ^c _w may be the same or different. }
0 ≦ X ≦ 1.5 × Y (2)   The method for producing a rubber composition according to claim 1, wherein the maximum temperature of the rubber composition in the first stage is 120 to 190 ° C. The method for producing a rubber composition according to claim 1 or 2, wherein the silane coupling agent (C) is a compound represented by any one of the following chemical formulas (3) to (5).

[Wherein, L is independently an alkanediyl group or alkenediyl group having 1 to 9 carbon atoms, and x = m and y = n. ]   The method for producing a rubber composition according to any one of claims 1 to 3, wherein the inorganic filler (B) is silica.   The manufacturing method of the rubber composition in any one of Claims 1-4 in which the said filler contains carbon black.   The method for producing a rubber composition according to any one of claims 1 to 5, wherein the inorganic filler (B) is 40% by mass or more in the filler.   The guanidine is at least one compound selected from 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine and 1-o-tolylbiguanide. A method for producing a rubber composition.   The rubber according to any one of claims 1 to 6, wherein the sulfenamide is N-cyclohexyl-2-benzothiazolylsulfenamide and / or N-tert-butyl-2-benzothiazolylsulfenamide. A method for producing the composition.   The method for producing a rubber composition according to any one of claims 1 to 6, wherein the thiazole is 2-mercaptobenzothiazole and / or di-2-benzothiazolyl disulfide.   The method for producing a rubber composition according to any one of claims 1 to 9, wherein 50 mol% or more of the organic acid compound is stearic acid. The method for producing a rubber composition according to any one of claims 1 to 9 , wherein 50 mol% or more in the organic acid compound is rosin acid and / or fatty acid contained in the emulsion-polymerized styrene-butadiene copolymer.   In the first step, the rubber component (A), all or part of the inorganic filler (B) and all or part of the silane coupling agent (C) are kneaded and then the vulcanization accelerator (D The method for producing a rubber composition according to any one of claims 1 to 11, further kneaded.

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