JP6385655B2 - Method for producing rubber composition - Google Patents

Description

  The present invention relates to a rubber composition, and more particularly to a method for producing a rubber composition containing silica, and a rubber composition and a pneumatic tire obtained thereby.

  In order to reduce the heat generation of the rubber composition, it is known to add silica as a reinforcing filler. However, silica easily aggregates due to the influence of silanol groups present on the surface and is inferior in dispersibility, so that it is difficult to sufficiently exhibit its performance. Therefore, in order to improve the dispersibility of silica, a silane coupling agent is used in combination. The silane coupling agent is added to and mixed with the rubber component together with the silica to react with the silanol groups on the silica surface and react with the polymer of the rubber component to link the two together and disperse the silica. To improve.

  Therefore, in the rubber composition containing silica, the reactivity between silica and the silane coupling agent is important in order to stably exhibit the characteristics. When the reaction rate of the silane coupling agent is low, the overall physical properties of the rubber composition, particularly the processability and low heat generation performance, are inferior. For example, when used in a tire tread, low fuel consumption performance (rolling resistance performance) It is difficult to fully demonstrate. On the other hand, in order to increase the reactivity, it is inferior in efficiency, that is, production efficiency, that the number of steps is repeated or mixed for a long time in the mixing process or the extrusion process. Therefore, it is desirable to improve rubber physical properties such as processability and low heat generation performance while suppressing deterioration of production efficiency, that is, it is required to improve production efficiency and rubber physical properties in a balanced manner.

  By the way, Patent Document 1 discloses a method for measuring the reaction rate of an added silane coupling agent in a silica-blended rubber composition. In Patent Document 2, silica and a silane coupling agent are added to a rubber component and mixed to obtain a non-pro rubber mixture in which the reaction rate of the silane coupling agent is 50 to 80%. It is disclosed that the reaction of the silane coupling agent is allowed to proceed gently by aging, thereby improving the balance between processability, reinforcement and low heat generation performance. However, further improvement is required to improve workability and low heat generation performance without deteriorating production efficiency.

JP 2010-216952 A JP 2012-255048 A

  An object of the present invention is to provide a production method capable of improving the balance between production efficiency and rubber physical properties such as processability and low heat generation performance in a rubber composition containing silica.

The method for producing a rubber composition according to the present invention includes a step of obtaining a first rubber mixture in which a reaction rate of a silane coupling agent is A% by adding and kneading silica and a silane coupling agent to a rubber component; Adding a silica and a silane coupling agent to the rubber component and kneading and mixing to obtain a second rubber mixture in which the reaction rate of the silane coupling agent is B% higher than the A%; and the first rubber mixture; And a step of mixing the second rubber mixture at a ratio of 8 to 40% by mass with respect to the total amount of the second rubber mixture.

The method according to claim 1, wherein the reaction ratio of the first rubber mix is A = 50 to 75%, the reaction rate of the second rubber mixture Ri B = 70 to 95% der, the first rubber mixture and the second rubber mixture, the rubber component, the formulation of the silica and silane coupling agent that are common. In the manufacturing method according to claim 2, a reaction rate of the first rubber mixture is A = 50 to 75%, a reaction rate of the second rubber mixture is B = 70 to 95%, and the first rubber is The mixture and the second rubber mixture each contain or do not contain a vulcanizing additive comprising a vulcanizing agent and a vulcanization accelerator, and the first rubber mixture and the second rubber mixture contain the vulcanizing system. additives excluding compounding that are common.

  The rubber composition according to the present invention is obtained by these production methods, and the pneumatic tire according to a preferred embodiment of the present invention uses the rubber composition for at least a part thereof. .

  According to the present invention, the first rubber mixture containing silica and the silane coupling agent is blended with the second rubber mixture having a higher reaction rate of the silane coupling agent, thereby suppressing the deterioration in production efficiency. Further, the viscosity of the rubber composition can be lowered to improve processability, and the low heat generation performance can be improved.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The method for producing a rubber composition according to this embodiment includes a step of obtaining a first rubber mixture by adding and mixing silica and a silane coupling agent to a rubber component (hereinafter referred to as step (1)), and a rubber component. A step of obtaining a second rubber mixture by adding and mixing silica and a silane coupling agent (hereinafter referred to as step (2)), and a step of mixing the first rubber mixture and the second rubber mixture (hereinafter referred to as steps). Step (3)).

  In the present embodiment, the rubber component is not particularly limited. For example, natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber, butadiene -Isoprene rubber, styrene-butadiene-isoprene rubber, nitrile rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like can be used, and these can be used alone or in combination of two or more. More preferably, it is NR, SBR, BR, or a blend rubber of two or more thereof.

  The diene rubber was also selected from the group consisting of an amino group, a hydroxyl group, an epoxy group, an alkoxy group, an alkylsilyl group, an alkoxysilyl group, and a carboxyl group at the molecular terminal or molecular chain of those listed above. A modified diene rubber modified with the functional group by introducing at least one functional group may be used. These functional groups interact with silanol groups on the surface of silica particles (reactivity and affinity), and can improve the dispersibility of silica. The usage-amount of this modified diene rubber is not specifically limited, For example, 1-50 mass parts may be sufficient among 100 mass parts of rubber components, and 5-30 mass parts may be sufficient as it.

In the present embodiment, the silica is not particularly limited, but wet silica such as wet precipitation silica or wet gel silica is preferably used. Colloidal properties of the silica is not particularly limited, for example, (measured according to BET method according to JIS K6430) BET specific surface area may also be used as a 80~300m ² / g, 150~230m ² / You may use what is g. The compounding quantity of a silica is not specifically limited, For example, it is 5-150 mass parts with respect to 100 mass parts of rubber components, More preferably, it is 10-120 mass parts, More preferably, it is 30-100 mass parts. .

In this embodiment, as a silane coupling agent, what contains sulfur in a molecule | numerator is used preferably, and various sulfur containing silane coupling agents mix | blended with a silica in a rubber composition can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) disulfide, bis ( Sulfide silanes such as 3-trimethoxysilylpropyl) tetrasulfide and bis (2-trimethoxysilylethyl) disulfide; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3 - mercaptopropyl dimethyl methoxy silane, mercaptoethyl triethoxysilane _formula: HS- table in _{(CH 2) 3 -Si (OC} 2 H 5) m (O (C 2 H 4 O) k -C 13 H 27) n Evo Click-Degussa Co. "VP Si363" (where, m = average 1, n = average 2, k = average 5) mercaptosilane such as, 3-octanoylthio-1-propyltriethoxysilane (Formula: _CH 3 ( CH ₂ ) ₆ C (═O) S— (CH ₂ ) ₃ —Si (OC ₂ H ₅ ) ₃ ), protected mercaptosilanes such as 3-propionylthiopropyltrimethoxysilane (ie, the mercapto group is an acyl group) A silane compound having a protected thiol ester structure), and the like can be used singly or in combination of two or more. It is preferable that the compounding quantity of a silane coupling agent is 2-25 mass parts with respect to 100 mass parts of silica, More preferably, it is 4-15 mass parts.

  The rubber composition according to this embodiment is usually blended with a vulcanizing agent and a vulcanization accelerator. Although it does not specifically limit as a vulcanizing agent, Usually, sulfur is used. Examples of sulfur as a vulcanizing agent include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and oil-treated sulfur. These may be used alone or in combination of two or more. Although it does not specifically limit as a compounding quantity of a vulcanizing agent, It is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of said rubber components, More preferably, it is 0.5-5 mass parts. is there.

  Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N-oxydiethylene-2- Sulfenamides such as benzothiazolylsulfenamide (OBS) and N, N-diisopropyl-2-benzothiazolylsulfenamide (DPBS), tetramethylthiuram disulfide (TMTD), tetrabutylthiuram disulfide (TBTD), etc. Thiuram series, 1,3-diphenylguanidine (DPG), guanidine series such as 1,3-di-O-tolylguanidine (DOTG), dibenzothiazolyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), etc. And thiazole series. These can be used alone or in combination of two or more. Although it does not specifically limit as a compounding quantity of a vulcanization accelerator, It is preferable that it is 0.1-7 mass parts with respect to 100 mass parts of said rubber components, More preferably, it is 0.5-5 mass parts. It is.

  In the rubber composition according to this embodiment, in addition to the above-described components, other reinforcing fillers such as carbon black, softeners such as process oil, plasticizers, anti-aging agents, zinc white, stearic acid, wax Various additives usually used in the rubber industry, such as resins, can be blended.

  In the said process (1), the 1st rubber mixture whose reaction rate of a silane coupling agent is A% is obtained by adding and mixing a silica, a silane coupling agent, and another additive to a rubber component. . Mixing can be performed using various mixers generally used in the rubber field, for example, a Banbury mixer, a roll, a kneader, etc., preferably using a closed kneader such as a Banbury mixer.

  The other additives added in the step (1) may or may not include a vulcanizing additive composed of a vulcanizing agent and a vulcanization accelerator. When the first rubber mixture does not contain a vulcanizing additive, step (1) follows a normal non-pro kneading step, for example, the discharge temperature (maximum mixing temperature) is 160 ° C. or less (preferably 120 to 150 ° C.). It can carry out by mixing by the number of times of kneading once or several times. On the other hand, when the vulcanizing additive is included in the first rubber mixture, the step (1) is first carried out in accordance with a normal non-pro kneading process and excluding the vulcanizing additive. After mixing at a discharge temperature of 1 or a plurality of kneading times, a vulcanizing additive is added according to a normal professional kneading process, and a discharge temperature of 110 ° C. or less (preferably 80 to 100 ° C.) is 1 This can be done by mixing once.

  The higher reaction rate A of the silane coupling agent for the first rubber mixture is preferable, but in this embodiment, the reaction rate A is preferably 50 to 75% from the viewpoint of production efficiency. When the reaction rate A is 50% or more, the blend ratio of the second rubber mixture having a high reaction rate can be suppressed, and the production efficiency can be improved. More preferably, the reaction rate A = 55 to 70%.

  In the said process (2), the 2nd rubber mixture whose reaction rate of a silane coupling agent is B% is obtained by adding and mixing a silica, a silane coupling agent, and another additive to a rubber component. . About the mixer which can be used, the point which may or may not contain the vulcanizing additive, and the difference in the mixing method depending on the presence or absence of the vulcanizing additive are the same as in step (1), and the description is omitted. .

  The second rubber mixture is characterized in that the reaction rate of the silane coupling agent is higher than that of the first rubber mixture (that is, B%> A%). In step (2), in order to obtain a rubber mixture having a high reaction rate, the number of times of kneading in accordance with the non-pro kneading step may be larger than that in step (1). The reaction rate of the silane coupling agent for the second rubber mixture is preferably B = 70 to 95%, more preferably 75 to 90%. When the reaction rate B is higher than the reaction rate A and 70% or more, the effect of improving rubber properties can be enhanced when mixed with the first rubber mixture. The difference in reaction rate between the first rubber mixture and the second rubber mixture (BA (%)) is not particularly limited, but is preferably 10% or more, and more preferably 20% or more.

  In the present specification, the reaction rate of the silane coupling agent is measured by the method described in JP 2010-216952 A. That is, it is contained in the rubber mixture by performing an extraction treatment using a solvent in which the rubber component does not dissolve in the unvulcanized rubber mixture (however, an organic solvent in which a chemical containing an unreacted silane coupling agent is dissolved). The unreacted silane coupling agent is extracted, and the content of the reacted silane coupling agent is determined by quantifying the amount of sulfur contained in the rubber mixture after extraction. The reaction rate of the silane coupling agent can be determined by comparing the content with the blending amount of the silane coupling agent.

In detail, the reaction rate of a silane coupling agent is calculated | required by following formula (I).
Reaction rate (%) = {(S−S ₀ ) / S _r } × (m / m ₀ ) × 100 (I)
In the formula, S is a sulfur content (% by mass) contained in the rubber mixture after extraction. S ₀ is the sulfur content (% by mass) contained in the rubber mixture after extraction measured for a rubber mixture of the same composition excluding the silane coupling agent. _Sr is the sulfur content (mass%) by the silane coupling agent contained in the rubber mixture before extraction calculated from the blending amount of the silane coupling agent. m ₀ is the mass of the rubber mixture before extraction, and m is the mass of the rubber mixture after extraction.

  The first rubber mixture and the second rubber mixture can be blended differently, but basically it is preferable that the reaction rate of the silane coupling agent is different in the same blending system. Specifically, the first rubber mixture and the second rubber mixture have the same compounding for the rubber component, silica, and silane coupling agent (that is, the types and amounts of these components are the same). ) Is preferred. More preferably, the first rubber mixture and the second rubber mixture have the same composition except for the vulcanizing additive, that is, the blending of both is the same except for the presence or absence of the vulcanizing additive. It is preferable that the two silane coupling agent reaction rates differ depending on the number of times of kneading.

  In addition, any of process (1) and process (2) may be implemented first, and may be implemented simultaneously using a separate mixer, and the order is not ask | required.

  The step (3) is a step of mixing the first rubber mixture and the second rubber mixture, and corresponds to a final mixing step. The first rubber mixture and the second rubber mixture are blended so that the ratio of the second rubber mixture is 8% by mass or more with respect to the total amount of both. More preferably, it is 8-50 mass% (namely, 1st rubber mixture / 2nd rubber mixture (mass ratio) = 92 / 8-50 / 50), More preferably, it is 10-40 mass% (same mass ratio = 90). / 10-60 / 40), particularly preferably 15-30% by mass (the same mass ratio = 85 / 15-70 / 30). Thus, by blending the second rubber mixture having a high silane coupling agent reaction rate with the first rubber mixture having a low silane coupling agent reaction rate in a relatively small amount, the viscosity of the obtained rubber composition is increased. The processability is improved and the extrusion performance is improved. This can reduce the number of rubber re-kneading or extrusion steps up to the final mixing step. Moreover, the low heat generation performance of the obtained rubber composition can be improved, and the rolling resistance performance can be improved when used in a tire.

  Since the step (3) is a final mixing step, a predetermined amount of a vulcanizing additive necessary for the final rubber composition is added and mixed as necessary. For example, when no vulcanizing additive is added in both step (1) and step (2), a necessary amount of vulcanizing system is added when mixing the first rubber mixture and the second rubber mixture in step (3). What is necessary is just to add and mix an additive, and also when the vulcanization system additive is added in any one of process (1) and process (2), in process (3), the remaining vulcanization system addition What is necessary is just to add and mix an agent. In addition, since the vulcanization system additive is added in the process (3), it is preferable to mix once at the discharge temperature of 110 degrees C or less (preferably 80-100 degreeC) according to a normal professional kneading process. Usable mixers are the same as in step (1).

  In the present embodiment, each of the first rubber mixture and the second rubber mixture is obtained with a certain reaction rate, but measuring the reaction rate of the silane coupling agent itself is the production of the rubber composition of the present embodiment. It is not essential in the method. That is, when the rubber composition manufacturing process is determined, the reaction rate at each of the above stages is measured, and if the number of times of kneading is determined so that the reaction rate satisfies the predetermined condition, the actual rubber composition It is not necessary to measure the reaction rate in the production of. Of course, the method for producing the rubber composition may include a step for measuring the reaction rate.

  The use of the rubber composition thus obtained is not particularly limited, and tires (eg, parts such as treads, sidewalls, and bead parts), vibration-proof rubbers (eg, engine mounts, strut mounts, body mounts, Suspension bush, etc.), seismic isolation rubber (construction seismic isolation rubber, etc.), belts such as conveyor belts, etc. Preferably, it is used for tires, and rubber parts of various pneumatic tires can be constituted by vulcanization molding at 140 to 180 ° C., for example, according to a conventional method. As one embodiment, it is preferably used for a tread rubber and / or a sidewall rubber of a pneumatic tire, and a tire excellent in low fuel consumption performance can be produced by reducing rolling resistance.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. The raw materials used in the examples and comparative examples are as follows.

  According to the composition (parts by mass) shown in Table 1 below, a rubber mixture was prepared using a Banbury mixer at the number of times shown in Table 1. Specifically, for the rubber mixtures 1-1 to 1-4 and 2-1 to 2-4 which do not contain a vulcanizing additive, the compounding agents described in Table 1 are added to the rubber component, and the kneading described in Table 1 is performed. Mixing (discharge temperature = 150 ° C.) was performed so that the number of times reached. On the other hand, for rubber mixtures 1-5, 1-6, 2-5, and 2-6 containing a vulcanizing additive, first, a compounding agent excluding the vulcanizing additive is added to the rubber component and listed in Table 1. After kneading to the number of times less than the number of times of kneading (discharge temperature = 150 ° C.), vulcanizing additives are added and kneaded at the final kneading stage (discharge temperature = 100 ° C.), and total kneading Mixing was performed so that the number of times was the number of times described in Table 1. The details of each component in Table 1 are as follows.

・ SBR: "SBR1502" manufactured by JSR Corporation
-Modified SBR: alkoxy group and amino group terminal modified solution polymerization SBR, "HPR350" manufactured by JSR Corporation
-BR: “BR150B” manufactured by Ube Industries, Ltd.
・ NR: RSS No. 3 ・ Carbon black: FEF carbon black (N550)
・ Silica: “Nip seal AQ” manufactured by Tosoh Silica Co., Ltd. (BET = 205 m ² / g)
Silane coupling agent: bis (3-triethoxysilylpropyl) disulfide, “Si75” manufactured by Degussa
・ Oil: “Process NC140” manufactured by JX Nippon Oil & Energy Sun Energy Co., Ltd.
・ Stearic acid: “Lunac S20” manufactured by Kao Corporation
・ Zinc flower: “Zinc flower 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
Anti-aging agent: “Antigen 6C” manufactured by Sumitomo Chemical Co., Ltd.
・ Wax: Nippon Seiki Co., Ltd. “OZOACE0355”
・ Vulcanization accelerator: “Soxinol CZ” manufactured by Sumitomo Chemical Co., Ltd.
・ Sulfur: “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.

  About each obtained rubber mixture, the reaction rate of the silane coupling agent was measured. The measuring method is as follows.

-Reaction rate of silane coupling agent: According to the method described in Japanese Patent Application Laid-Open No. 2010-216952, a sheet-like sample having a thickness of 1 mm or less adjusted to mass m ₀ = 1.00 g was subjected to Soxhlet extraction with acetone for 8 hours. The rubber mixture after extraction was vacuum-dried at 30 ° C. for 5 hours, and the mass m was measured. Subsequently, the sulfur content S (sulfur concentration: mass%) contained in the rubber mixture after extraction was determined by an ion chromatograph “ICS-1500” manufactured by Nippon Dionex Co., Ltd. Further, the same rubber composition was prepared by the same operation except that the silane coupling agent was not blended in the blending shown in Table 1, and the sulfur content S _O (mass%) contained in the rubber mixture after extraction was determined. The reaction rate of the silane coupling agent was determined from the formula (I). Incidentally, the sulfur content S _{r (wt%)} with a silane coupling agent contained in the rubber mixture before extraction which is calculated from the amount of the silane coupling agent, the rubber mixture 1-1 through 1-4 and 2-1 It is 0.536% in ˜2-4, and 0.528% in rubber mixture 1-5, 1-6, 2-5, 2-6.

  Next, by using the above rubber mixture and final mixing using a Banbury mixer according to the composition (parts by mass) described in Table 2 and Table 3 below (discharge temperature = 100 ° C.), a rubber composition for a tire tread A product was prepared. Whether or not the rubber mixture contains a vulcanizing additive, the amount of the vulcanization accelerator and sulfur finally contained in each rubber composition is 0 with respect to 100 parts by mass of the rubber component. It was added and mixed at this stage as necessary so as to be 0.7 parts by mass and 2.2 parts by mass.

  The reaction rate of the silane coupling agent in Table 2 and Table 3 is the reaction rate for the rubber mixture used, and when blending, it was calculated by proportional calculation according to the blend ratio. The number of times of kneading is the total number of times of kneading until the final rubber composition is obtained (the final mixing process is also added as one time). When blending two types of rubber mixtures, proportional calculation according to the blend ratio Calculated by

  About each obtained rubber composition, the Mooney viscosity in an unvulcanized state was measured as a processability parameter | index. Further, the rubber composition was applied to a cap tread of a tire having a tread having a cap / base structure, and a 205 / 65R159H pneumatic radial tire was produced according to a conventional method, and rolling resistance was evaluated. Each measurement / evaluation method is as follows.

(Mooney viscosity)
In accordance with JIS K6300, using a rotorless Mooney measuring machine manufactured by Toyo Seiki Seisakusho, the unvulcanized rubber is preheated at 100 ° C. for 1 minute, and the torque value after 4 minutes is measured in Mooney units. Table 2 shows the values of Comparative Example 2 and Table 3 shows the values of Comparative Example 6 as 100, respectively. The smaller the index, the lower the viscosity and the better the workability.

(Rolling resistance)
Rolling resistance when running at 23km and 80km / h on a single-axis drum tester for rolling resistance measurement, with a rim of 15x6.5JJ and tires mounted, air pressure of 230kPa and load of 4.4kN It was measured. The results are shown as an index with Table 2 indicating the value of Comparative Example 2 and Table 3 indicating the value of Comparative Example 6 as 100, respectively. The smaller the index, the lower the rolling resistance (excellent in low heat generation performance), and thus the lower fuel consumption performance.

  As shown in Table 2, since the reaction rate of the silane coupling agent was lower in Comparative Example 1 than in Comparative Example 2 corresponding to the control, processability and fuel efficiency were inferior. On the other hand, when Example 1 was blended with a rubber mixture 1-1 having a low reaction rate of 55% and a rubber mixture 1-3 having a high reaction rate of 87%, a relatively small amount (35% by mass) was compared. Compared to Example 2, while reducing the number of times of kneading, the workability and the low fuel consumption performance were equal or less, and the balance between production efficiency and rubber physical properties (workability / low fuel consumption performance) was improved.

  In Comparative Example 3, the rubber mixture 1-1 having a reaction rate of 55% was blended at 5% by mass with the rubber mixture 1-4 having a reaction rate of 92%, and the blend amount of the rubber mixture having a high reaction rate There was too little, and it was inferior to the improvement effect of workability and low exothermic performance. On the other hand, in Example 2 in which the rubber mixture 1-1 having a reaction rate of 55% and 10% by mass of the rubber mixture 1-4 having a reaction rate of 92% were blended, the number of times of kneading was compared with that of Comparative Example 3. While suppressing the increase, the workability and fuel efficiency performance are remarkably improved, and the number of times of kneading can be reduced while the processability and fuel efficiency performance are comparable to Comparative Example 2, Excellent balance between production efficiency and rubber properties.

  Example 3 is a mixture of rubber mixture 1-1 having a reaction rate of 55% and 20% by mass of rubber mixture 1-4 having a reaction rate of 92%. While suppressing, the processability and fuel efficiency were significantly improved.

  In Example 4, a rubber mixture 1-1 having a reaction rate of 55% was blended with 15% by mass of a rubber mixture 1-5 having a reaction rate of 76%, and the rubber mixture having a high reaction rate was vulcanized. This example includes additives, but in this case as well, the number of times of kneading is reduced and the processability and fuel efficiency are less than or equal to those of the comparative example 2, which is the control. The balance of (/ low fuel consumption performance) has been improved.

  In Example 5, a rubber mixture 1-2 having a reaction rate of 72% was blended with 10% by mass of a rubber mixture 1-6 having a reaction rate of 89% and containing a vulcanizing additive. On the other hand, the workability and fuel efficiency were significantly improved while suppressing the increase in the number of times of kneading. Also, compared to Comparative Example 4 where the reaction was 76% and rubber mixture 1-5 containing a vulcanizing additive alone was used, the workability and fuel efficiency were improved while reducing the number of times of kneading. Excellent balance between production efficiency and rubber properties.

  Table 3 uses rubber mixtures 2-1 to 2-6 containing a modified diene rubber as the rubber mixture. In this case as well, almost the same results as in Table 2 described above were obtained. Example 6 The balance between production efficiency and rubber physical properties (processability / low fuel consumption performance) was improved.

Claims (3)

Adding a silica and a silane coupling agent to the rubber component and kneading to obtain a first rubber mixture in which the reaction rate of the silane coupling agent is A%;
Adding a silica and a silane coupling agent to the rubber component and kneading to obtain a second rubber mixture in which the reaction rate of the silane coupling agent is B% higher than the A%;
Mixing the first rubber mixture and the second rubber mixture in a ratio of 8 to 40% by mass of the second rubber mixture with respect to the total amount of both;
Only including,
The reaction rate of the first rubber mixture is A = 50 to 75%, the reaction rate of the second rubber mixture is B = 70 to 95%,
The said 1st rubber mixture and the 2nd rubber mixture are the manufacturing methods of the rubber composition with which the compounding about a rubber component, a silica, and a silane coupling agent is common . Adding a silica and a silane coupling agent to the rubber component and kneading to obtain a first rubber mixture in which the reaction rate of the silane coupling agent is A%;
Adding a silica and a silane coupling agent to the rubber component and kneading to obtain a second rubber mixture in which the reaction rate of the silane coupling agent is B% higher than the A%;
Mixing the first rubber mixture and the second rubber mixture in a ratio of 8 to 40% by mass of the second rubber mixture with respect to the total amount of both;
Only including,
The reaction rate of the first rubber mixture is A = 50 to 75%, the reaction rate of the second rubber mixture is B = 70 to 95%,
The first rubber mixture and the second rubber mixture each contain or do not contain a vulcanizing additive comprising a vulcanizing agent and a vulcanization accelerator, and the first rubber mixture and the second rubber mixture are A method for producing a rubber composition having a common composition excluding the vulcanizing additive . The manufacturing method of the pneumatic tire which manufactures a rubber composition by the method of Claim 1 or 2 , and manufactures a pneumatic tire using the obtained rubber composition.