JP2021102721A - Method for producing rubber composition and method for manufacturing pneumatic tire - Google Patents

Abstract

To provide a method for producing a rubber composition excellent in dispersibility of silica and capable of reducing power consumption consumed in the whole production process.SOLUTION: The method for producing a rubber composition comprises a kneading process of kneading a rubber composition containing at least a rubber component, silica and a silane coupling agent in a kneading chamber provided in a closed kneader. The closed kneader includes: a neck part positioned above the kneading chamber and having a cylindrical space therein; and a ram capable of vertically moving in the cylindrical space of the neck part and capable of pressing the rubber composition in the kneading chamber from above when kneading the rubber composition. In the kneading process, the rubber composition is kneaded with the temperature controlled within a predetermined temperature range, while maintaining the ram in a non-pressing state, for a fixed period of time.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a rubber composition having a step of kneading a rubber composition containing a rubber component, silica and a silane coupling agent, and a method for producing a pneumatic tire obtained from the rubber composition as a raw material. Is.

In recent years, silica has come to be used as a filler for rubber reinforcement instead of carbon black. However, since silica has a weaker reinforcing property against rubber than carbon black, it is common to add a silane coupling agent when silica is blended with a rubber component in order to enhance this reinforcing property. By adding the silane coupling agent as a compounding agent, the silane coupling agent is immobilized on silica by the coupling reaction, and the rubber component reacts with the silane coupling agent, so that the dispersibility of silica in rubber is improved. As a result, the reinforcing property is enhanced.

By the way, in order to efficiently carry out the reaction between silica and the silane coupling agent, it is desirable to knead the rubber composition containing the rubber component, silica and the silane coupling agent at a specific temperature for a long time. In a low temperature environment, the coupling reaction between silica and the silane coupling agent is unlikely to occur, but if the temperature becomes too high, a cross-linking reaction of rubber occurs, and the viscosity rapidly increases and gels.

When kneading is performed in a kneading chamber equipped with a closed kneader in the presence of rubber components, silica, and a silane coupling agent, heat is generated by the viscous flow of rubber and heat generated by the coupling reaction. The temperature in the kneading chamber rises. Therefore, there is a problem that the temperature rises to the gelling temperature in a short time, and the coupling reaction time cannot be sufficiently taken.

In Patent Document 1 below, a kneading step of kneading a rubber component, silica and a silane coupling agent using a closed kneader, and a rubber ingot obtained by kneading following the kneading step are subjected to a high temperature below the closed kneader. Described is a method for producing a rubber composition, which comprises a holding step of holding the rubber ingot for a predetermined time in an atmosphere to supply the amount of heat required for the reaction of silica and a silane coupling agent to the rubber block.

In Patent Document 2 below, a rubber component, silica and a silane coupling agent are added and kneaded to obtain a first kneaded product, and the first kneaded product is further kneaded to obtain a second kneaded product. It includes two steps and a third step of adding a second kneaded product and a vulcanizing chemical and kneading to obtain an unvulcanized rubber composition, and was set in the range of 150 to 170 ° C. in the first step. A method for producing a rubber composition for a tire is described in which a reaction process of kneading a rubber component, silica and a silane coupling agent while maintaining a reaction temperature is carried out until a specific condition is satisfied.

In Patent Document 3 below, a rubber component, silica and a silane coupling agent are added and kneaded to obtain a first kneaded product, and the first kneaded product is further kneaded to obtain a second kneaded product. It includes two steps and a third step of adding a second kneaded product and a vulcanizing chemical and kneading to obtain an unvulcanized rubber composition, and was set in the range of 110 to 130 ° C. in the first step. The reaction process of kneading the rubber component, silica and silane coupling agent while maintaining the reaction temperature is performed for 90 seconds or more when the reaction temperature is 110 ° C. or higher and lower than 120 ° C., and 30 when the reaction temperature is 120 to 130 ° C. A method for producing a rubber composition for a tire, which is carried out for a second or longer, is described.

Japanese Unexamined Patent Publication No. 2012-184289 JP-A-2018-70753 JP-A-2018-104586

However, in any of the techniques described in the patent documents, it is necessary to carry out the kneading step a plurality of times in order to improve the dispersibility of silica in the rubber composition and further to reduce the viscosity of the rubber composition. Therefore, it has been found that while the power consumption in the entire manufacturing process of the rubber composition increases, there is room for further improvement in the dispersibility of silica.

The present invention aims to solve the above problems, and an object of the present invention is to provide a method for producing a rubber composition, which has excellent dispersibility of silica and can reduce power consumption consumed in the entire production process.

The above problem can be achieved by the following configuration. The present invention is a method for producing a rubber composition, which comprises a kneading step of kneading a rubber composition containing at least a rubber component, silica and a silane coupling agent in a kneading chamber provided with a closed type kneader. The kneading machine is located above the kneading chamber and can move up and down in a neck portion having a tubular space inside and in the tubular space of the neck portion, and at the time of kneading the rubber composition, The rubber composition in the kneading chamber is provided with a ram capable of pressing the rubber composition from above, and the kneading step keeps the ram in a non-pressed state for a certain period of time within a predetermined temperature range. The present invention relates to a method for producing a rubber composition, which comprises a step of kneading in a temperature-controlled state.

In the method for producing a rubber composition, the kneading chamber is a kneading chamber provided with a kneading rotor capable of automatically controlling the rotation speed by a control unit and capable of detecting and outputting the internal temperature, and the kneading chamber is capable of detecting and outputting the internal temperature. Prior to the step, there is a preparatory step of setting the control time and the target temperature for the control unit, and the kneading step includes information on the measured temperature in the kneading chamber until the control time elapses. It is preferable that the step is to knead the kneading chamber while automatically controlling the rotation speed by PID control for setting the measured temperature to the target temperature by the control unit based on the target temperature.

In the method for producing a rubber composition, at least the rubber component, the silica and the silane coupling agent are kept in a state where the kneading step is temperature-controlled to a temperature lower than the lower limit temperature at which the coupling reaction between silica and the silane coupling agent proceeds. The first step of kneading the rubber composition containing the above, and the second step of kneading the rubber composition while advancing the coupling reaction in a state where the temperature is controlled to be equal to or higher than the lower limit temperature at which the coupling reaction proceeds. It is preferable that the second step is a step of kneading the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range.

In the method for producing a rubber composition, the kneading chamber is a kneading chamber provided with a kneading rotor capable of automatically controlling the rotation speed by a control unit, capable of detecting and outputting the internal temperature, and the kneading chamber. Prior to the step, there is a preparatory step of setting the control time and the target temperature for the control unit, and all of the first step and the second step included in the kneading step are until the control time elapses. During the period, the kneading chamber is kneaded while automatically controlling the rotation speed by PID control for setting the measured temperature to the target temperature by the control unit based on the information on the measured temperature in the kneading chamber and the target temperature. It is preferably a step.

Further, the present invention manufactures an unvulcanized tire using a material process for producing a rubber composition by the method for producing a rubber composition according to any one of the above and the rubber composition produced in the material process. It relates to a method of manufacturing a pneumatic tire including a process.

The method for producing a rubber composition according to the present invention includes a kneading step of kneading the ram from the rubber composition in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. In such a kneading step, the rubber composition is kneaded from the rubber composition in a non-pressed state, that is, in a state where at least a part of the kneading chamber is open, so that while removing volatile substances such as moisture, The rubber composition can be kneaded with fresh oxygen mixed in. Therefore, the effect of reducing the viscosity of the rubber composition and the effect of dispersing silica are excellent. In particular, when the kneading step includes the first step and the second step in which the temperature range to be controlled is different, and the rotation speed of the kneading rotor provided in the kneading chamber is automatically controlled by the PID control by the control unit, each of them. In each step, the temperature in the kneading chamber can be kept within a certain range for a certain period of time. As a result, kneading can be performed in the kneading chamber for a certain period of time while maintaining the temperature, so that the dispersibility of silica is improved as compared with the conventional configuration in which the rubber compound is discharged when the temperature reaches a certain temperature or higher. An excellent rubber compound can be produced. Further, since the man-hours in the kneading process can be reduced, the power consumption in the entire manufacturing process can be reduced. In particular, when the silica finally contained in the rubber composition is collectively added in the kneading process, the man-hours in the kneading process can be significantly reduced, so that the power consumption consumed in the entire manufacturing process can be significantly reduced. Become.

This is an example of a closed kneader that can be used in the manufacturing method according to the present invention.

The method for producing a rubber composition according to the present invention includes a kneading step of kneading a rubber composition containing at least a rubber component, silica and a silane coupling agent in a kneading chamber provided with a closed kneader, and the kneading step. However, it is characterized in that it is a step of kneading the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. Such temperature control may be one step in which the temperature range to be controlled is one step, but in the present invention, the kneading step in particular has two steps in the temperature range to be controlled, specifically, the following first step. It is preferable to include a two-step kneading step including one step and a second step.

[First step]
In the first step, the rubber composition containing at least the rubber component, silica and the silane coupling agent is kneaded at a temperature below the lower limit at which the coupling reaction between silica and the silane coupling agent proceeds.

As the rubber component, a diene-based rubber can be preferably used. Examples of the diene rubber include natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), and butadiene rubber containing syndiotactic-1,2-polybutadiene (SPB). Examples thereof include chloroprene rubber (CR) and nitrile rubber (NBR), which can be used alone or as a blend of two or more kinds. Examples of these exemplified diene-based rubbers include those having a modified end (for example, terminal-modified BR, terminal-modified SBR, etc.) or those modified to impart desired properties (for example, modified), if necessary. NR) can also be used. As the terminal-modified diene-based rubber, a diene-based rubber in which the polymer end is modified with various modifying agents can be used, and various known modification methods can be used. Specifically, as the modifier, tin compound, aminobenzophenone compound, isocyanate compound, diglycidylamine compound, cyclic imine compound, halogenated alkoxysilane compound, glycidoxypropylmethoxysilane compound, neodium compound, alkoxysilane compound, amine Examples thereof include a combination of a compound and an alkoxysilane compound. In the case of synthetic rubber, the polymerization method and molecular weight are not particularly limited, and a combination of rubber type and blend ratio can be appropriately selected depending on the site and application in which the rubber composition is used. Regarding polybutadiene rubber (BR), in addition to those synthesized using a cobalt (Co) catalyst, a neodymium (Nd) catalyst, a nickel (Ni) catalyst, a titanium (Ti) catalyst, and a lithium (Li) catalyst, WO2007 Those synthesized by using the polymerization catalyst composition containing the metallocene complex described in −129670 can also be used. Among these diene-based rubbers, the use of BR and / or SBR is preferable, the use of SBR is more preferable, and the use of modified SBR modified with amine and alkoxysilane is particularly preferable.

As the silica, wet silica, dry silica, sol-gel silica, surface-treated silica and the like used for ordinary rubber reinforcement are used. Of these, wet silica is preferable.

The silane coupling agent is not particularly limited as long as it contains sulfur in the molecule, and various silane coupling agents blended with silica in the rubber composition can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide (for example, "Si69" manufactured by Degusa), bis (3-triethoxysilylpropyl) disulfide (for example, "Si75" manufactured by Degusa), bis (2-tri). Propylsilanes such as ethoxysilylethyl) tetrasulfide, bis (4-triequitysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltri Mercaptosilanes such as methoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, 3-propionylthiopropyltri Protected mercaptosilanes such as methoxysilane can be mentioned.

In the method for producing a rubber composition according to the present invention, when the total amount of the rubber components is 100 parts by mass at the time of the first step of the kneading step, the blending amount of silica is preferably 30 to 150 parts by mass. Conventionally, when the blending amount of silica in the rubber composition is set within such a range, the silica is kneaded in a plurality of times or the rubber composition once kneaded is kneaded again in order to improve the dispersibility of the silica. However, in the present invention, in the first step, the kneading step is carried out in a state where the silica is highly filled, and more preferably, the silica finally contained in the rubber composition is collectively charged in the kneading step. Can be carried out. Moreover, by carrying out the second step, which will be described later, following the first step (without discharging the rubber composition), the silica in the rubber composition is collectively charged, the dispersibility of the silica is improved, and a plurality of silicas are dispersed. Since it is not necessary to knead repeatedly, it is possible to reduce the power consumption in the kneading process.

In the method for producing a rubber composition according to the present invention, the blending amount of silica in the rubber composition in the kneading step is 30 to 150 parts by mass and 80 to 130 parts by mass when the total amount of the rubber components is 100 parts by mass. It is preferably a part. The blending amount of the silane coupling agent is preferably 2 to 15 parts by mass, more preferably 6 to 13 parts by mass with respect to 100 parts by mass of silica.

In the first step, the lower limit temperature at which the coupling reaction between silica and the silane coupling agent proceeds is appropriately determined by the combination of silica and the silane coupling agent. For example, a sulfide bond is formed by the coupling reaction. In this case, the lower limit temperature at which the coupling reaction proceeds is in the range of 135 to 145 ° C, and more specifically, about 140 ° C. Therefore, in the first step, it is preferable to knead the rubber composition while controlling the temperature in the range of 90 to 130 ° C., and it is more preferable to knead the rubber composition while controlling the temperature in the range of 100 to 120 ° C. preferable. Examples of the method of controlling the temperature within such a temperature range include a PID control method, which will be described later.

In the first step of the kneading step, the fill factor indicating the volume of the rubber composition with respect to the capacity of the kneading chamber provided in the closed kneader is preferably 70 to 80%. Even if kneading is carried out in a state where the fill factor is less than 70%, the viscosity of the rubber composition is low, the temperature rise tends to proceed, and as a result, temperature control may become difficult. On the other hand, if the fill factor exceeds 80%, the rubber composition may be insufficiently mixed and it may be difficult to improve the dispersibility of silica.

In the present invention, the fill factor can be specifically calculated by the following formula.
[Fill factor] = ([Volume of rubber composition] / [Capacity of kneading chamber provided in closed kneader]) × 100

The method for producing a rubber composition according to the present invention improves the dispersibility of silica while collectively adding silica in the rubber composition even if the fill factor is a high fill factor mixture of about 70 to 80%. Moreover, since it is not necessary to knead a plurality of times, it is possible to reduce the power consumption in the kneading process.

[Second step]
In the second step, the rubber composition is kneaded while advancing the coupling reaction in a state where the temperature is controlled to be equal to or higher than the lower limit temperature at which the coupling reaction proceeds. As described above, for example, when a sulfide bond is formed by a coupling reaction, the lower limit temperature at which the coupling reaction proceeds is in the range of 135 to 145 ° C, and more specifically, it is about 140 ° C. In the two steps, it is preferable to knead the rubber composition while controlling the temperature within the range of 140 to 170 ° C., and more preferably to knead the rubber composition while controlling the temperature within the range of 145 to 165 ° C. As a method of controlling the temperature within such a temperature range, for example, a PID control method can be mentioned as in the first step.

In the present invention, since the first step is carried out following the first step (without discharging the rubber composition), the mixing ratio of silica to the rubber component and the fill factor in the second step are the same as those in the first step. ..

The present invention is characterized in that the kneading step is a step of kneading the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. When the kneading step includes two steps including the first step and the second step, the second step kneads the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. It is preferable that the step is to be performed. This point will be described later.

In the present invention, the PID control method can be preferably used in both the first step and the second step. Specifically, the following manufacturing method;
The kneading chamber is a kneading chamber equipped with a kneading rotor capable of automatically controlling the rotation speed by a control unit and capable of detecting and outputting the internal temperature, and controls the control unit before the kneading process. It has a preparatory step for setting the time and target temperature, and both the first step and the second step included in the kneading step provide information on the measured temperature in the kneading chamber and the target temperature until the control time elapses. Based on this, a method for producing a rubber composition, which is a step of kneading the kneading chamber while automatically controlling the rotation speed by PID control for setting the measured temperature as the target temperature by the control unit, can be preferably carried out.

As a method for producing a rubber composition according to the present invention, for example, a closed kneader can be used. As such a closed kneader, a meshing type intermix type mixer, a tangential type Banbury type mixer, a pressure type kneader and the like can be used, and the meshing type intermix type mixer is particularly preferable.

The closed-type kneader 1 shown in FIG. 1 is a closed-type mixer, and is charged for charging a cylinder 2 used for raising and lowering the ram 4, and a rubber composition containing at least a rubber component, silica, and a silane coupling agent. It is provided with a mouth 3, a kneading chamber 5 for kneading the rubber composition, and a drop door 7 for discharging the kneaded rubber composition. The ram 4 is arranged to adjust the pressure in the kneading chamber 5 by raising and lowering.

When the ram 4 is pressed against the rubber composition in the kneading chamber while the ram 4 is descending (pressed state), the rubber composition is kneaded while keeping the kneading chamber in a closed state. In the present invention, the kneading step is kneaded in a temperature-controlled state within a predetermined temperature range while the ram is held in a non-pressed state for a certain period of time. That is, by raising the ram 4 for a certain period of time in the kneading step, the kneading chamber 5 is held in an open state (non-pressed state). Therefore, the rubber composition is kneaded with fresh oxygen mixed in while removing volatile substances such as water from the rubber composition.

The kneading chamber 5 is provided with a pair of kneading rotors 6 for kneading the materials, and the kneading rotor 6 is rotationally driven around a rotating shaft 12 by a motor (not shown). Further, the kneading chamber 5 is provided with a temperature sensor 13 for detecting the temperature in the chamber. The temperature sensor 13 may be installed inside the drop door 7, for example.

The rotation speed of the motor that rotates the kneading rotor 6 is adjusted based on the control signal from the control unit 11. The control unit 11 controls the rotation speed of the motor based on the temperature information in the kneading chamber 5 sent from the temperature sensor 13. The motor may have a configuration in which the rotation speed can be freely changed by the control unit 11, and is composed of, for example, an inverter motor.

More specifically, the rotation speed of the motor is proportional to the deviation between the measured temperature Tp in the kneading chamber 5 detected by the temperature sensor 13 and the target temperature Ts by the PID calculation processing unit provided inside the control unit 11. PID control based on the execution of the operations (P), integral (I), and derivative (D) is performed. That is, the PID calculation processing unit calculates the control amount in proportion to the difference (deviation e) between the measured temperature Tp and the target temperature Ts in the kneading chamber 5 detected by the temperature sensor 13, and the proportional (P) operation and deviation. The control amount of each control amount obtained by the integral (I) operation of calculating the control amount by the integral value obtained by integrating e in the time axis direction and the differential (D) operation of calculating the control amount from the gradient of the change of the deviation e, that is, the differential value. The total value determines the rotational speed of the motor.

The flow of the method for producing a rubber composition using the PID control method in the kneading step including the first step and the second step is shown below. When the rubber component, silica, and silane coupling agent are charged into the closed kneader 1, in the first step, based on the values of _{the target temperature T s1} and the control set time t _{m1 input in advance in the preparation step.} , The control unit 11 starts PID control to the motor. That is, the rotation speed of the motor is determined based on the control signal from the control unit 11, and the rotation speed of the kneading rotor 6 is determined thereby. As described above, the target temperature T _s1 in the first step is preferably 90 to 130 ° C., and the control set time t _m1 is preferably 10 to 150 seconds, more preferably 40 to 90 seconds.

Regarding the method of charging the rubber component, silica, and the silane coupling agent, each of the rubber component, silica, and the silane coupling agent may be charged independently into the closed kneader 1, or the rubber component and the silane coupling agent may be charged. After adding silica, a certain kneading treatment may be performed, and then the silane coupling agent may be added.

The control unit 11 performs PID control on the rotation speed of the motor until the elapsed time t from the control start time becomes the control set time t _{m1 or more.} The specific control contents, as described above, the deviation of the measured temperature Tp and the target temperature T _s of the kneading chamber 5 sent from the temperature sensor 13, the integral value of the deviation, based on the differential value of the deviation, the rotational speed Change in small steps.

Then, when the control time t becomes the control set time t _m1 or more, the control unit 11 ends the PID control to the motor, and then raises the temperature of the rubber composition until the _{target temperature T s1 in the second step is reached.} Let me. The subsequent steps are the same as in the first step, and in the second step, the control unit 11 starts PID control to the motor based on the values of _{the target temperature T s2} and the control set time t _{m2 input in advance.} The control set time t _m2 is set to a time exceeding the minimum time required for the coupling reaction between silica and the silane coupling agent. As described above, the target temperature T _s2 in the second step is preferably 140 to 170 ° C., and the control set time t _{m 2} is preferably 30 to 300 seconds.

In the case of the method for producing a rubber composition using the PID control method in the kneading step including the first step and the second step, preferably, in the second step, the ram is held in a non-pressed state for a certain period of time. It is preferable to knead in a state where the temperature is controlled within a predetermined temperature range. In the second step, the time for holding the ram in the non-pressed state is preferably 5 seconds or longer, preferably 30 seconds or longer, and preferably 60 seconds or longer. However, if the ram is raised immediately after reaching the control temperature in the second step to bring it into a non-pressing state, the temperature control of the rubber composition tends to become unstable, so the second step is not performed immediately after the start of the second step. It is preferable to put it in a non-pressed state in the middle or the end of the step.

After the kneading step including the first step and the second step is completed, the rubber composition is discharged from the drop door 7. Then, a vulcanization-based compounding agent such as sulfur and a vulcanization accelerator is added to the cooled rubber composition and kneaded to produce the rubber composition.

In the method for producing a rubber composition according to the present invention, even if the fill factor is a high fill factor mixture of about 70 to 80%, the power consumption in the kneading step is reduced while adding silica in the rubber composition all at once. However, it is possible to produce a rubber composition having excellent dispersibility of silica. The method for producing a pneumatic tire according to the present invention includes a material process for producing a rubber composition by the method for producing a rubber composition and a step for producing an unvulcanized tire using the rubber composition produced in the material process. And include. The pneumatic tire manufactured in the present invention is excellent in WET grip performance and rolling resistance because it is excellent in dispersibility of silica. Specific examples will be described below.

In each example and comparative example, the following materials were used.
(material)
-SBR; product name "SBR1502", manufactured by JSR, modified S-SBR; product name "HPR350", manufactured by JSR, silica; product name "Nipseal AQ", manufactured by Toso, silane coupling agent; product name "Si75" , Degusa's stearic acid; "Lunac S-20", Kao's carbon black (N339); product name "Seast KH", Tokai Carbon's oil; product name "Process NC-140", JX Zinc oxide manufactured by Nikko Nisseki Energy Co., Ltd .; trade name "Zinc oxide 2 types", wax manufactured by Mitsui Metal Mining Co., Ltd .; trade name "OZOACE355", manufactured by Nippon Seiko Co., Ltd. , Tsurumi Chemical Industry Co., Ltd., Refining Accelerator 1; Product Name "Suncellor DM-G", Sanshin Chemical Industry Co., Ltd., Refining Accelerator 2;

Comparative Example 1
The formulation shown in "1st" in Table 1 was put into a Banbury mixer which is a closed kneader, a kneading step was carried out without PID control, and the rubber composition was discharged when the temperature reached 160 ° C. During the kneading process, kneading was carried out while maintaining the descending state of the ram (pressed state). Then, for the purpose of improving the dispersibility of silica and reducing the viscosity, the rubber composition obtained in "1st" is kneaded as it is without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. Was carried out twice. Finally, the vulcanization compounding agent (sulfur and vulcanization accelerator) described in "Final" is added, the kneading step is carried out without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. As a result, a rubber composition was produced.

Table 1 shows the energy consumption (electric energy) of the obtained rubber composition, the Mooney viscosity, and the wet road surface property and fuel efficiency of the pneumatic tire produced from the obtained rubber composition as a raw material.

[Energy consumption (electric energy) of rubber composition]
The amount of electric power consumed from the 1st step to the final step was expressed by index evaluation with Comparative Example 1 as 100. The lower the value, the smaller the energy consumption (electric energy).

[Moony Viscosity]
_{The Mooney viscosity ML (1 + 4)} at 100 ° C. was measured according to JIS K6300, and the index was expressed with Comparative Example 1 as 100. The smaller the index, the lower the viscosity and the better the workability.

[WET grip performance]
Four 205 / 65R15 test radial tires were mounted, and the tires were run on a road surface sprinkled with water at a water depth of 2 to 3 mm, and the friction coefficient was measured at a speed of 100 km / h to evaluate the wet grip performance. Comparative Example 1 is displayed as an exponential notation as 100, and the larger the exponent, the better the wet grip performance.

[Rolling resistance]
Using the same 205 / 65R15 test radial tire as the above wet grip performance test, in accordance with JISD4234: 2009, at rim (15 x 6JJ), internal pressure (230kPa), load (3.43kN), speed (80km / h) The rolling resistance when running was measured, and it was displayed as an index when Comparative Example 1 was set to 100. The smaller the index, the better.

Comparative Example 2
The formulation shown in "1st" in Table 1 was put into a rubbery mixer, which is a closed kneader, and the kneading process was carried out while performing PID control in which the control temperature range was one step (one step), and the temperature reached 160 ° C. The rubber composition was discharged at this stage. During the kneading process, kneading was carried out while maintaining the descending state of the ram (pressed state). Then, for the purpose of improving the dispersibility of silica and reducing the viscosity, the rubber composition obtained in "1st" is kneaded as it is without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. Was carried out once. Finally, the vulcanization compounding agent (sulfur and vulcanization accelerator) described in "Final" is added, the kneading step is carried out without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. As a result, a rubber composition was produced.

Example 1
The formulation shown in "1st" in Table 1 was put into a rubbery mixer, which is a closed kneader, and the kneading process was carried out while performing PID control in which the control temperature range was one step (one step), and the temperature reached 160 ° C. The rubber composition was discharged at this stage. Of the 120 seconds of PID control, kneading was performed while raising the ram (non-pressed state) for 60 seconds at the end. Then, for the purpose of improving the dispersibility of silica and reducing the viscosity, the rubber composition obtained in "1st" is kneaded as it is without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. Was carried out once. Finally, the vulcanization compounding agent (sulfur and vulcanization accelerator) described in "Final" is added, the kneading step is carried out without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. As a result, a rubber composition was produced.

Example 2
The formulation shown in "1st" in Table 1 was put into a rubbery mixer, which is a closed kneader, and the kneading process was carried out while performing PID control in which the control temperature range was set to 2 steps (2 steps), and the temperature reached 160 ° C. The rubber composition was discharged at this stage. Of the 120 seconds of the second control time in the second step of the kneading step, kneading was carried out while raising the ram (non-pressing state) for 60 seconds at the final stage. Then, for the purpose of improving the dispersibility of silica and reducing the viscosity, the rubber composition obtained in "1st" is kneaded as it is without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. Was carried out once. Finally, the vulcanization compounding agent (sulfur and vulcanization accelerator) described in "Final" is added, the kneading step is carried out without PID control, and the rubber composition is discharged when the temperature reaches 160 ° C. As a result, a rubber composition was produced.

Example 3
Of the 120 seconds of the second control time in the second step of the kneading step, the rubber composition was kneaded by the same method as in Example 2 except that the kneading was carried out while raising the ram (non-pressing state) for 5 seconds in the final stage. Manufactured.

Example 4
Of the 120 seconds of the second control time in the second step of the kneading step, the rubber composition was kneaded by the same method as in Example 2 except that the kneading was carried out while raising the ram (non-pressed state) for 100 seconds in the final stage. Manufactured.

Example 5
Of the second control time of 120 seconds in the second step of the kneading process, kneading was performed while raising the ram (non-pressing state) for an intermediate 60 seconds (pressed state 30 seconds → non-pressed state 60 seconds → pressed state). A rubber composition was produced by the same method as in Example 2 except for 30 seconds).

Example 6
Of the 120 seconds of the second control time in the second step of the kneading process, the ram was repeatedly lowered (pressed state) and raised (non-pressed state), and kneading was performed while keeping the non-pressed state for a total of 60 seconds. , A rubber composition was produced by the same method as in Example 2.

The rubber compositions obtained in Comparative Examples 1 and 2 and Examples 1 to 6 were applied to a tire tread to prepare a test tire, and WET grip performance and rolling resistance were measured.

From the results in Table 1, since the rubber compositions obtained in Examples 1 to 6 have excellent silica dispersibility, the pneumatic tire provided with the tire tread obtained from the rubber composition as a raw material has WET grip performance and rolling. It turns out that it has excellent resistance.

Claims (5)

A method for producing a rubber composition, which comprises a kneading step of kneading a rubber composition containing at least a rubber component, silica and a silane coupling agent in a kneading chamber provided with a closed kneader.
The closed kneader is located above the kneading chamber, has a neck portion having a tubular space inside, and can move up and down in the tubular space of the neck portion, and is capable of moving up and down in the tubular space of the neck portion. It is provided with a ram capable of pressing the rubber composition in the kneading chamber from above at the time of kneading.
A method for producing a rubber composition, wherein the kneading step is a step of kneading the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. The kneading chamber is provided with a kneading rotor capable of automatically controlling the rotation speed by a control unit, and is a kneading chamber capable of detecting and outputting the internal temperature.
Prior to the kneading step, there is a preparatory step for setting the control time and the target temperature for the control unit.
Until the control time elapses, the kneading step rotates by PID control for setting the measured temperature to the target temperature by the control unit based on the information on the measured temperature in the kneading chamber and the target temperature. The method for producing a rubber composition according to claim 1, which is a step of kneading the kneading chamber while automatically controlling the speed. The rubber composition containing at least the rubber component, the silica and the silane coupling agent is kneaded in a state where the kneading step controls the temperature below the lower limit temperature at which the coupling reaction between silica and the silane coupling agent proceeds. The first step and
Including a second step of kneading the rubber composition while advancing the coupling reaction in a state where the temperature is controlled to be equal to or higher than the lower limit temperature at which the coupling reaction proceeds.
The method for producing a rubber composition according to claim 1, wherein the second step is a step of kneading the ram in a non-pressed state for a certain period of time while controlling the temperature within a predetermined temperature range. .. The kneading chamber is provided with a kneading rotor capable of automatically controlling the rotation speed by a control unit, and is a kneading chamber capable of detecting and outputting the internal temperature.
Prior to the kneading step, there is a preparatory step for setting the control time and the target temperature for the control unit.
In both the first step and the second step included in the kneading step, the measured temperature is measured by the control unit based on the information on the measured temperature in the kneading chamber and the target temperature until the control time elapses. The method for producing a rubber composition according to claim 3, which is a step of kneading the kneading chamber while automatically controlling the rotation speed by PID control for setting the target temperature. A material step for producing a rubber composition by the method for producing a rubber composition according to any one of claims 1 to 4, and a step for producing an unvulcanized tire using the rubber composition produced in the material step. How to manufacture pneumatic tires including and.

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