Method for manufacturing rubber composition

Abstract

To improve uniformity of properties of a kneaded product even between batches with different water contents of silica.SOLUTION: A method for manufacturing a rubber composition disclosed herein comprises: providing materials containing rubber and silica; measuring a moisture content of the provided silica; setting a temperature T1 at which the materials are kneaded depending on the moisture content; and kneading the materials at the temperature T1 using a closed kneader. According to this configuration, uniformity of a property of the kneaded product can be improved even between batches in which the moisture content of silica differs from one another.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a rubber composition. [Background technology]

[0002] JP 2016-8235 A discloses a method for producing a rubber composition for tires that contains at least a rubber component and silica. The method includes a step of kneading the raw materials of the rubber composition for tires in an internal mixer, and is characterized in that a treatment for reducing the amount of moisture contained in the silica is carried out prior to the kneading step. The publication exemplifies a moisture reduction treatment for silica in which the silica is heated at a temperature of 100° C. for at least 10 minutes. It also describes that carrying out such a treatment can suppress the ejection of powdered compounding agents from the kneading chamber during kneading in the internal mixer.

[0003] JP 2012-185102 A discloses a method for mixing fillers in a process using a rubber mixer for mixing fillers as compounding agents. This mixing method includes a step of measuring the moisture content of the entire amount of filler to be added before the filler is added to the rubber mixer. In this method, if the moisture content measured in the above step is greater than the standard moisture content, the filler is dried to the standard moisture content before being added to the rubber mixer. In addition, if the moisture content measured in the above step is the same as the standard moisture content, the filler is directly added to the rubber mixer. In addition, if the moisture content measured in the above step is less than the standard moisture content, water is added to the filler to the standard moisture content before being added to the rubber mixer. The publication states that this method allows the moisture content of the entire filler to be accurately grasped, so that a filler with a constant moisture content can always be added to the mixer.

[0004] The rubber mixing method disclosed in JP 2006-205584 A uses a rubber mixing facility equipped with a mixing means, a weighing means, a moisture content measuring means for measuring the moisture content of the silica in the process of conveying the silica weighed by the weighing means to the mixing means, a water supplying means for supplying water to the silica weighed by the weighing means, and a control means for controlling the weighing means, the moisture content measuring means, and the water supplying means. This rubber mixing method is configured to calculate the moisture deficiency amount with respect to the target moisture content based on the actual moisture content measured by the moisture content measuring means and the weight of the silica measured by the weighing means, control the amount of water supplied from the water supplying means based on the moisture deficiency amount, and mix the silica that has received the water supply into the rubber compound together with a silane coupling agent in the mixing means. The publication states that in this rubber kneading method, the moisture content of the silica is measured prior to kneading and the moisture content can be brought close to a target value, thereby stabilizing the reaction between the silica and the silane coupling agent when the silica is kneaded into the rubber compound, thereby stabilizing the quality of the rubber compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-8235 A [Patent Document 2] JP 2012-185102 A [Patent Document 3] JP 2006-205584 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a material containing rubber and silica is kneaded, the moisture content of the silica varies from batch to batch, which may cause a difference in the progress of the reaction in the material. The present inventors wish to improve the uniformity of the properties of the kneaded product even between batches with different moisture contents of the silica. [Means for solving the problem]

[0007] The method for producing a rubber composition disclosed herein includes the steps of preparing a material containing rubber and silica, measuring the moisture content of the prepared silica, setting a temperature T1 for kneading the material according to the moisture content, and kneading the material at temperature T1 using an internal kneader. With this configuration, it is possible to improve the uniformity of the properties of the kneaded product even between batches in which the moisture content of the silica differs from one another. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a kneader 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the method for producing a rubber composition disclosed herein will be described with reference to the drawings. The technology disclosed herein is not limited to the following embodiments. The drawings are drawn diagrammatically and do not necessarily reflect the actual product. The drawings only show an example, and do not limit the technology disclosed herein unless otherwise specified. The same reference numerals are appropriately used for members and parts that perform the same function, and duplicated explanations are omitted. The notations "L", "R", "U", and "D" in the drawings represent "left", "right", "upper", and "lower", respectively. In this specification, the notation "P~Q" for a numerical range means "P or more and Q or less", and also means "P or more and less than Q", "P and less than Q", and "P and Q or less".

[0010] <Method for producing rubber composition> The method for producing a rubber composition disclosed herein includes, for example, a preparing step, a measuring step, a setting step, and a kneading step.

[0011] - Preparation process - The preparation step is, for example, a step of preparing a constituent material of a rubber composition to be produced by the production method disclosed herein. In this embodiment, in the preparation step, a material containing rubber and silica is prepared. As the rubber, any rubber used for this type of application can be used without any particular limitation. As the rubber, for example, natural rubber (NR); synthetic rubber such as isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene butadiene isoprene rubber (SBIR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene rubber (EPR), and butyl rubber (BR); can be mentioned. These may be used alone or in combination of two or more kinds.

[0012] As the silica, silica used for this kind of application is used without any particular limitation. The silica may be either silica (anhydrous silicic acid) prepared by a dry method or silica (hydrated silicic acid) prepared by a wet method. The silica prepared by a dry method may be, for example, silica prepared by a combustion method or silica prepared by an arc method. The silica prepared by a wet method may be, for example, silica prepared by a precipitation method or silica prepared by a gel method. From the viewpoint of preferably realizing the effect of the technology disclosed herein, it is preferable that the silica is silica prepared by a wet method having a relatively high moisture content. The above-mentioned silica may be used alone or in combination of two or more kinds.

[0013] The amount of silica is not particularly limited, but can be set to 10 to 200 parts by mass per 100 parts by mass of rubber. From the viewpoint of applying the technology disclosed herein, the amount of silica is, for example, 50 parts by mass or more, preferably 75 parts by mass or more, and more preferably 100 parts by mass or more per 100 parts by mass of rubber. On the other hand, from the viewpoint of suppressing poor dispersion of silica, the amount of silica is preferably 175 parts by mass or less, and more preferably 150 parts by mass or less per 100 parts by mass of rubber.

[0014] If necessary, additives may be added to the material. Examples of additives include fillers other than silica (e.g., carbon black, zinc oxide, calcium carbonate, etc.), silane coupling agents, silanes, resins, oils, antioxidants, potassium tetraborate, processing aids, metal release agents, waxes, sulfur, vulcanization accelerators, and vulcanization accelerator assistants. The type and content of the additives can be appropriately set.

[0015] According to the knowledge of the present inventor, the moisture content of silica prepared by a wet method (for example, a precipitation method) is generally 4% by mass to 8% by mass, but it is known that it increases or decreases from this range depending on the lot, environment, etc. Therefore, due to the variation in the moisture content of silica, the progress of the reaction in the material during kneading varies, and the characteristics of the kneaded product vary from batch to batch, which may lead to variation in the processability of the kneaded product. The present inventor wanted to improve the uniformity of the characteristics of the kneaded product between batches.

[0016] The inventors of the present invention have conducted a study on the properties related to the processability of the kneaded product, focusing on the Mooney viscosity. Through such a study, it has been found that the Mooney viscosity of the kneaded product tends to decrease as the moisture content of silica increases, and the Mooney viscosity of the kneaded product tends to increase as the moisture content of silica decreases. Furthermore, the inventors of the present invention have found that, when kneading materials, the Mooney viscosity increases as the temperature in the kneading tank of the kneading machine increases, and the Mooney viscosity decreases as the temperature in the kneading tank decreases. The inventors of the present invention have come up with the idea of ​​measuring the moisture content of silica prepared as a material, and adjusting the temperature in the kneading tank of the kneading machine according to the moisture content. Hereinafter, an embodiment of the manufacturing method disclosed herein will be described for the case where the property of the kneaded product to be improved in batch-to-batch uniformity is the Mooney viscosity.

[0017] -Measurement process- The measuring step is, for example, a step of measuring the moisture content of silica. The moisture content of silica is, for example, the ratio (mass%) of moisture contained in silica when the total amount of silica prepared in the preparation step is taken as 100 mass%. The method of measuring the moisture content of silica is not particularly limited. For example, the weight W0 of silica at room temperature (about 23°C) is measured, and the weight W1 of silica when the silica is heated at a predetermined temperature (for example, 150°C to 250°C) for a predetermined time is subtracted to obtain the weight W of moisture contained in silica. w The weight of water W w The moisture content of silica can be obtained based on the above. The moisture content of silica can be measured using, for example, a commercially available heat-drying moisture meter.

[0018] -Setting process- The setting step is, for example, a step of setting a temperature T1 at which the material is kneaded. Here, the temperature T1 is set according to the moisture content of the silica measured in the measuring step. The temperature T1 is, for example, the temperature in the kneading tank of the kneader (here, the set temperature). For example, from the viewpoint of promoting the reaction in the kneading step described later, the temperature T1 is preferably room temperature or higher, more preferably 30°C or higher, and more preferably 40°C or higher. On the other hand, for example, from the viewpoint of suppressing a rapid rise in the temperature in the kneading tank due to the reaction in the kneading step proceeding too much, the temperature T1 is preferably about 120°C or lower, more preferably 100°C or lower, and more preferably 90°C or lower.

[0019] The temperature T1 is set to the standard kneading temperature T0, for example, when the moisture content of silica is within the range of a predetermined standard moisture content. The range of the standard moisture content is, for example, the range of the moisture content of silica when materials with only the moisture content of silica being different are kneaded under predetermined kneading conditions, and the Mooney viscosity of the obtained kneaded product falls within a specified range (X to Y (X > 0, Y > 0, and X < Y)). Also, prior to determining the range of the standard moisture content, it is advisable to predetermine the temperature at which the materials are kneaded. Such a predetermined temperature can be set as the standard kneading temperature T0. Also, the specified range of the Mooney viscosity is, for example, the range of the Mooney viscosity that realizes suitable processability in the kneaded product. Note that the kneading conditions when determining the range of the standard moisture content can be appropriately set according to, for example, the type of kneader, the composition of the materials, the desired amount of the kneaded product, the composition of the kneaded product, and the like.

[0020] On the other hand, when the moisture content of silica obtained in the measurement step is higher than the upper limit in the range of the standard moisture content, the Mooney viscosity of the kneaded product may become smaller than the lower limit (here, X) of the specified range. From such a viewpoint, for example, the temperature T1 may be set to a temperature higher than the standard kneading temperature T0. Alternatively, when the moisture content of silica obtained in the measurement step is lower than the lower limit in the range of the standard moisture content, the Mooney viscosity of the kneaded product may become larger than the upper limit (here, Y) of the specified range. From such a viewpoint, for example, the temperature T1 may be set to a temperature lower than the standard kneading temperature T0.

[0021] The standard kneading temperature T0 can be appropriately set depending on, for example, the type of kneader, the composition of the material, the amount of the desired kneaded product, the composition of the kneaded product, etc. Although not particularly limited as long as the effect of the technology disclosed herein can be realized, the standard kneading temperature T0 is preferably set to about 20°C to 100°C. Considering that the temperature T1 is set to a temperature higher or lower than the standard kneading temperature T0 as necessary, the standard kneading temperature T0 is, for example, room temperature or higher, may be 30°C or higher, preferably 40°C or higher, preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher. In addition, the standard kneading temperature T0 is, for example, 95°C or lower, may be 90°C or lower, may be 80°C or lower, preferably 75°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower.

[0022] The range of the standard moisture content can be appropriately set depending on, for example, the type of kneader, the composition of the material, the amount of the desired kneaded product, the composition of the kneaded product, etc. Although not particularly limited as long as the effects of the technology disclosed herein can be realized, the range of the standard moisture content can be set to about 4% by mass to 8% by mass. From the viewpoint of making the properties of the kneaded product (here, Mooney viscosity) more uniform between batches, it is preferable that the range of the standard moisture content is set narrower than the above range. In this case, it is preferable that the range of the standard moisture content is set to 5.5% by mass to 7.5% by mass.

[0023] The specified range of the Mooney viscosity can be appropriately set, for example, depending on the application of the kneaded product, the type of device for processing the kneaded product, etc., while taking into consideration the processability of the kneaded product. From this viewpoint, the Mooney viscosity of the kneaded product is preferably 75 or less, more preferably 70 or less. In addition, the Mooney viscosity of the kneaded product is preferably 55 or more. In a preferred embodiment, the specified range of the Mooney viscosity is 55 or more and 70 or less.

[0024] -Kneading process- The kneading process is, for example, a process of kneading materials using an internal kneader. The internal kneader is, for example, a kneader mixer, a Banbury mixer, or the like. In the following, an embodiment in which a Banbury mixer is used as the internal kneader is described, but it is not intended that the internal kneader used in the technology disclosed herein is limited to a Banbury mixer. As the internal kneader used in the technology disclosed herein, a kneader mixer can also be preferably used, similar to a Banbury mixer. FIG. 1 is a cross-sectional view of a kneader 1. The configuration of the kneader 1 shown in FIG. 1 is merely an example, and as the internal kneader 1, a commercially available kneader used for this type of application can be used without particular limitation. As shown in FIG. 1, the kneader 1 includes a kneading tank (kneading chamber) 11, a supply chamber 12, and an input section 13. The kneading tank 11 is, for example, a portion where materials are kneaded. In this embodiment, the kneading tank 11 is connected to the supply chamber 12 via a connection port 11a.

[0025] In this embodiment, the kneading tank 11 is provided with a pair of rotors R. For example, the material is kneaded in the kneading tank 11 by the rotation of the pair of rotors R, and a kneaded product is prepared. As shown in FIG. 1, the kneading tank 11 has a discharge port 11b at the bottom. For example, the kneaded product prepared in the kneading tank 11 is discharged to the outside of the kneader 1 through the discharge port 11b. As shown in FIG. 1, a door 11c is attached to the discharge port 11b. For example, the kneading tank 11 can be opened to the outside by opening the door 11c, and the kneading tank 11 can be sealed by closing the door 11c.

[0026] The supply chamber 12 is, for example, a space that serves as a passageway for the material and the floating weight 12a. As shown in FIG. 1, the supply chamber 12 is a cylindrical space extending in the vertical direction. In this embodiment, the supply chamber 12 is provided with an input section 13. The input section 13 is a section where the material is input into the kneader 1. The material input from the input section 13 passes through the supply chamber 12 and the connection port 11a, and is input into the kneading tank 11.

[0027] In this embodiment, the supply chamber 12 is provided with a floating weight (ram) 12a and a shaft 12b. The floating weight 12a is, for example, a member that closes the connection port 11a. In this embodiment, the floating weight 12a is lowered in the supply chamber 12 to close the connection port 11a, thereby sealing the inside of the kneading tank 11. The shaft 12b is, for example, a member that supports the floating weight 12a and moves it vertically in the supply chamber 12. As shown in FIG. 1, the shaft 12b extends upward from the floating weight 12a.

[0028] In kneading using the kneader 1, for example, first, the floating weight 12a is raised above the input part 13, and the material is input from the input part 13 into the kneading tank 11. Next, the floating weight 12a is lowered in the supply chamber 12 to close the connection port 11a and seal the kneading tank 11. Next, the rotor R is rotated to knead the material in the kneading tank 11 and produce a kneaded product. The obtained kneaded product is then discharged outside the kneader 1.

[0029] In this embodiment, in the kneading step, the material is kneaded at a temperature T1. Here, the temperature of the kneading tank 11 is set to the temperature T1. The total kneading time in this step is not particularly limited, and can be set appropriately in consideration of, for example, the physical properties of the kneaded product.

[0030] The kneaded product obtained as described above can be molded into a sheet shape, for example, by passing it through an extruder (not shown). Such a sheet-shaped molded product can be used, for example, as a rubber composition for tires or a high-damping rubber composition for vibration-damping devices. This rubber composition for tires can be used, for example, for passenger cars, large vehicles such as buses and trucks, and racing cars. This rubber composition for tires can be used, for example, as a rubber composition for tread rubber, a rubber composition for sidewall rubber, etc., and can be preferably used as a rubber composition for tread rubber.

[0031] As described above, the method for producing a rubber composition disclosed herein includes a preparation step, a measurement step, a setting step, and a kneading step. In the preparation step, a material containing rubber and silica is prepared. In the measurement step, the moisture content of the prepared silica is measured. In the setting step, the temperature T1 at which the material is kneaded is set according to the moisture content. In the kneading step, the material is kneaded at the temperature T1 using an internal kneader. In this production method, the silica moisture content is measured for each batch of material, and the kneading temperature T1 is set. This allows the material to be kneaded at a temperature appropriate for each batch. This makes it possible to increase the uniformity of the properties (e.g., Mooney viscosity) of the kneaded product between batches. In addition, in the production method disclosed herein, it is possible to omit the installation of equipment, steps, etc. for drying silica.

[0032] In the setting step, when the moisture content of silica is within a predetermined range of standard moisture content, the temperature T1 may be set to a predetermined standard kneading temperature T0. When the moisture content of silica is higher than the upper limit of the range of the standard moisture content, the temperature T1 may be set to a temperature higher than the standard kneading temperature T0. When the moisture content of silica is lower than the lower limit of the range of the standard moisture content, the temperature T1 may be set to a temperature lower than the standard kneading temperature T0. By configuring the setting step in this way, the kneading temperature T1 can be made appropriate for each batch. Therefore, the effect of the technology disclosed herein can be better realized.

[0033] The temperature T1 may be set to 40° C. or higher and 90° C. or lower, which allows better control of the progress of the reaction in the kneading step.

[0034] The standard moisture content may be in the range of 5.5% by mass or more and 7.5% by mass or less when the total mass of the prepared silica is taken as 100% by mass. By setting the standard moisture content in the above range, the uniformity of the properties of the kneaded product between batches can be further improved.

[0035] The standard kneading temperature T0 may be set to 50° C. or higher and 70° C. or lower. When the moisture content of silica is within the range of the standard moisture content, the standard kneading temperature T0 (temperature T1 in this case) being within the above range allows the kneaded product to have desirable properties. Even when the moisture content of silica is outside the range of the standard moisture content, the standard kneading temperature T0 being within the above range allows the appropriate temperature T1 to be set, allowing the kneaded product to have desirable properties.

[0036] In the preparation step, a material containing 100 parts by mass or more of silica per 100 parts by mass of rubber may be prepared. The effect of the technology disclosed herein is more preferably realized when obtaining a kneaded product of a material containing more silica than rubber.

[0037] Test examples relating to the present disclosure will be described below, but it is not intended that the present disclosure be limited to those shown in these test examples.

[0038] "material" A material containing rubber, silica, and additives containing carbon black and oil was prepared. The compounding amounts of each component in this material were 120 parts by mass of silica, 3 parts by mass of carbon black, and 30 parts by mass of oil per 100 parts by mass of rubber. The rubber prepared contained natural rubber (TSR20) and synthetic rubbers SBR and BR. The silica was "Nipsil VN3" manufactured by Tosoh Corporation. The carbon black was "Seat 3" manufactured by Tokai Carbon Co., Ltd.

[0039] "Measuring the moisture content of silica" The silica was subjected to a treatment to adjust the moisture content. The moisture content of the silica was then measured. Here, a heat-drying moisture meter ("MX-50" manufactured by A&D Co., Ltd.) was used, and the moisture content (mass%) of each silica was measured based on the value obtained by subtracting the weight of each silica when heated at 200°C from the weight of each silica at room temperature, following the manual for the measuring device. The heating of the silica was stopped when the weight change rate of the silica became 0.05% / min. The results are shown in the "Moisture content (mass%)" column in Table 1.

[0040] "Example 1" A material containing rubber, silica, carbon black, oil, resin, vulcanization accelerator, and silane was prepared. This material was put into a kneader mixer (manufactured by Moriyama Manufacturing Co., Ltd., capacity: 3 L) as an internal kneader, and kneaded to produce the kneaded product of this example. In the kneading in this example, the temperature in the kneading tank of the kneader mixer was set to 60°C, and the rotor rotation speed was set to 30 rpm. When the temperature of the kneader reached 150°C, the material was kneaded for another 15 minutes, and kneading was completed. The total kneading time here was 30 minutes.

[0041] "Example 2" Silica having the moisture content shown in Table 1 was used. In addition, when the materials were kneaded, the temperature inside the kneading tank of the kneader mixer was set to 90° C. Other than these, the same materials and procedures as in Example 1 were used to prepare the kneaded product of this example.

[0042] "Example 3" Silica having the moisture content shown in Table 1 was used. In addition, when the materials were kneaded, the temperature inside the kneading tank of the kneader mixer was set to 40° C. Other than these, the same materials and procedures as in Example 1 were used to prepare the kneaded product of this example.

[0043] "Comparative Example 1" When the materials were kneaded, the temperature inside the kneading tank of the kneader mixer was set to 60° C. Other than these, the same materials and procedures as in Example 2 were used to prepare the kneaded product of this example.

[0044] "Comparative Example 2" When the materials were kneaded, the temperature inside the kneading tank of the kneader mixer was set to 60° C. Other than these, the same materials and procedures as in Example 3 were used to prepare the kneaded product of this example.

[0045] "Measurement of Mooney Viscosity" The kneaded products obtained in each example were measured for Mooney viscosity (ML) at 130°C based on JIS K6301 using a commercially available measuring device (Shimadzu Corporation's "SMV300"). 1+4 ) was measured. Examples having a Mooney viscosity of 55 or more and 75 or less were evaluated as "○ (pass)", and examples having a Mooney viscosity of less than 55 or more than 75 were evaluated as "× (fail)". The evaluation results are shown in the corresponding columns of Table 1 together with the measured Mooney viscosity values.

[0046] [Table 1]

[0047] As shown in Table 1, according to Examples 1 to 3, by setting the temperature for kneading the materials according to the measured moisture content of the silica and kneading the materials at that temperature, it was found that the uniformity of the properties of the kneaded product (here, Mooney viscosity) between batches can be improved even if the materials have different moisture contents.

[0048] The manufacturing method of the rubber composition disclosed herein has been described above, but the manufacturing method disclosed herein is not limited to the above-mentioned embodiment and modified examples unless otherwise specified. In addition, the respective configurations of the above-mentioned embodiment and modified examples can be appropriately combined as long as they are not mutually inhibiting. In addition, in the above-mentioned embodiment, the case where the property of the kneaded product to be improved in uniformity between batches is Mooney viscosity has been described. However, the property of such kneaded product is not limited to Mooney viscosity, and may be tan δ, silica dispersion ratio, etc.

[0049] The present invention (1) relates to a method for producing a rubber composition. Here, the method for producing a rubber composition in the present invention (1) includes the steps of: Providing a material comprising rubber and silica; Measuring the moisture content of the prepared silica; setting a temperature T1 at which the material is kneaded in accordance with the moisture content; kneading the material at the temperature T1 using an internal mixer; Includes.

[0050] The present invention (2) is In the setting step, When the moisture content is within a range of a predetermined standard moisture content, the temperature T1 is set to a predetermined standard kneading temperature T0; When the moisture content is higher than the upper limit of the range of the standard moisture content, the temperature T1 is set to a temperature higher than the standard kneading temperature T0; When the moisture content is lower than the lower limit of the range of the standard moisture content, the temperature T1 is set to a temperature lower than the standard kneading temperature T0. This is the production method described in present invention (1).

[0051] The present invention (3) is the production method according to the present invention (1) or (2), wherein the temperature T1 is set to 40° C. or higher and 90° C. or lower.

[0052] The present invention (4) is the production method according to the present invention (2), wherein the standard moisture content is in the range of 5.5% by mass or more and 7.5% by mass or less, when the total amount of the prepared silica is taken as 100% by mass.

[0053] The present invention (5) is the production method according to the present invention (2) or (4), in which the standard kneading temperature T0 is set to 50°C or higher and 70°C or lower.

[0054] The present invention (6) is the manufacturing method according to any one of the present inventions (1) to (5), wherein in the preparing step, the material contains 100 parts by mass or more of silica per 100 parts by mass of rubber. [Explanation of symbols]

[0055] 1. Mixer 11 Mixing tank 12 Supply room 13 Input section R rotor

Claims

1. Providing a material comprising rubber and silica; Measuring the moisture content of the prepared silica; The temperature T at which the material is kneaded is determined according to the moisture content. １ Setting Using an internal mixer, １ kneading the material with Including, A method for producing a rubber composition.

2. In the setting step, When the moisture content is within a predetermined range of standard moisture content, the temperature T １ at a predetermined standard kneading temperature T ０ Set it to When the moisture content is higher than the upper limit of the range of the standard moisture content, the temperature T １ The standard kneading temperature T ０ Set the temperature higher than When the moisture content is lower than the lower limit of the range of the standard moisture content, the temperature T １ The standard kneading temperature T ０ Set the temperature lower than 2. The method of claim 1.

3. The temperature T １ The manufacturing method according to claim 1 , wherein the temperature is set to 40° C. or higher and 90° C. or lower.

4. 3. The method according to claim 2, wherein the standard moisture content is in the range of 5.5% by mass or more and 7.5% by mass or less when the entire amount of the prepared silica is taken as 100% by mass.

5. The standard kneading temperature T ０ The manufacturing method according to claim 2 , wherein the temperature is set to 50° C. or higher and 70° C. or lower.

6. The manufacturing method according to claim 1 , wherein in the preparing step, the material is prepared containing 100 parts by mass or more of silica per 100 parts by mass of rubber.

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