JP2014217985A - Kneading method of rubber composition and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method capable of producing a rubber composition where the dispersibility of silica is excellent and the dynamic viscoelasticity of a vulcanized rubber is enhanced by appropriately adjusting the reaction amount of silica with a silane coupling agent in the rubber composition and determining an optimal reaction end point.SOLUTION: A closed mixer comprising: at least a casing and a rotor; a kneading part to knead a rubber composition; a neck part positioning at the upper part of the kneading part and having a cylindrical space inside; and a humidity sensor disposed at the side surface of the neck part, is used. The reaction end point of silica with a silane coupling agent is determined based on the difference between internal humidity measured by the humidity sensor with time and a prescribed humidity measured under an external atmosphere. Kneading is finished when being reached to a reaction end point.

Description

  The present invention relates to a method for kneading a rubber composition containing at least raw rubber, silica and a silane coupling agent, and a rubber composition.

  Silica is used as a filler for reinforcing rubber. Silica tends to aggregate particles due to hydrogen bonding of silanol groups which are surface functional groups. Therefore, when silica is blended in the rubber composition, it is preferable to add a silane coupling agent in order to improve the dispersion of silica. As a result, a coupling reaction between silica and a coupling agent is performed to improve dispersibility and suppress re-aggregation, thereby improving the low fuel consumption performance and wet road handling stability performance of the tire.

  When the silica and the silane coupling agent are reacted in the rubber composition, if the reaction amount between the silica and the silane coupling agent is insufficient, good dispersibility of the silica cannot be obtained. On the other hand, when the reaction amount of silica and the silane coupling agent is excessive, the rubber is overheated and the rubber physical properties may be deteriorated. Therefore, it is important to appropriately adjust the reaction amount of silica and the silane coupling agent in the rubber composition to determine the optimum reaction end point.

  In order to solve the above problem, in Patent Document 1 below, a necessary reaction amount between silica and a silane coupling agent to be achieved in the kneading operation is determined in advance by experiments, and the amount of kneading energy input from the start of the kneading operation The mixed rubber temperature was calculated over time based on the discharged amount, and the reaction amount between silica and the silane coupling agent was calculated over time based on the mixed rubber temperature, and the calculated reaction amount reached the required reaction amount. Sometimes a technique for terminating the kneading operation is described.

  Further, in Patent Document 2 below, in a kneading method of unvulcanized rubber in which silica and a coupling agent are blended with unvulcanized rubber in a mixing chamber and kneaded, water is supplied to the mixing chamber and from the mixing chamber A technique is described in which kneading is performed while maintaining the kneading temperature at 130 to 170 ° C. while removing the alcohol generated by the reaction of silica and the coupling agent.

JP 2004-358893 A JP 2006-123272 A

  However, each of the above prior arts has the following problems. That is, the rubber, silica, and coupling agent used as raw materials vary in physical properties and water content due to seasonal factors and storage conditions. Therefore, the technique described in Patent Document 1 uses silica based on past experimental data. Even when the required reaction amount between the silane coupling agent and the mixed rubber temperature was determined, it was difficult to accurately determine the end point of the reaction due to variations in physical properties and water content.

  In addition, in the technique described in Patent Document 2 below, the device for promoting the reaction between the silica and the coupling agent is devised, but the adjustment of the reaction amount between the silica and the silane coupling agent is merely adjusting the temperature. Therefore, it was difficult to accurately determine the end point of the reaction.

  The present invention has been made in view of the above circumstances, and its problem is to appropriately adjust the reaction amount of silica and a silane coupling agent in the rubber composition and determine the optimum reaction end point. An object of the present invention is to provide a production method capable of producing a rubber composition having excellent dispersibility of silica and improved dynamic viscoelasticity of vulcanized rubber.

  As a result of intensive studies to solve the above problems, the present inventor has paid attention to the amount of water generated proportionally with respect to the reaction amount of silica and the silane coupling agent, and in a closed mixer for kneading the rubber composition. It was found that the reaction end point between silica and the silane coupling agent can be accurately determined by measuring the internal humidity of the liquid and predicting the reaction amount between the silica and the silane coupling agent based on the measurement result. The present invention has been made based on such discovery and has the following configuration.

  That is, the present invention is a kneading method of a rubber composition containing at least raw rubber, silica and a silane coupling agent, and has a casing and a rotor, kneading the rubber composition, A hermetically sealed type comprising a neck portion that is located above and has a cylindrical space inside, a charging port provided at an upper portion on a side surface of the neck portion, and a humidity sensor provided on a side surface of the neck portion. Using a mixer, based on the difference between the internal humidity measured over time by the humidity sensor and the specified humidity measured in an external atmosphere, the reaction endpoint of the silica and the silane coupling agent is determined, The present invention relates to a kneading method for a rubber composition, wherein kneading is terminated when the reaction end point is reached.

  As described above, in the reaction between silica and a silane coupling agent, the silica and the silane coupling agent form a covalent bond by a dehydration condensation reaction (coupling reaction). That is, the amount of water generated in the closed mixer increases in proportion to the amount of coupling reaction between silica and the silane coupling agent. For this reason, in the closed mixer, the humidity (internal humidity) increases as compared to the specified humidity measured in an external atmosphere. That is, it is considered that the coupling reaction between the silica and the silane coupling agent proceeds at the stage where the internal humidity is increased. However, as the coupling reaction between the silica and the silane coupling agent approaches the end point, it is considered that the amount of water generated is proportional to the amount of coupling reaction. In other words, in the present invention, the difference between the internal humidity measured over time by the humidity sensor and the specified humidity measured in the external atmosphere is used as a scale, so that the coupling reaction between silica and the silane coupling agent is measured. The degree of progress can be accurately grasped. Thereby, in this invention, the reaction end point of a silica and a silane coupling agent can be correctly identified and determined. As a result, in the kneading method of the rubber composition according to the present invention, a rubber composition having excellent silica dispersibility and improved dynamic viscoelasticity of the vulcanized rubber can be produced.

  In the kneading method of the rubber composition, it is preferable that a reaction end point is a stage where the difference between the internal humidity and the specified humidity is within 25%. At this stage, the coupling reaction between the silica and the silane coupling agent has progressed sufficiently. By setting this stage as the reaction end point, rubber dispersibility can be prevented and vulcanization can be improved. A rubber composition with improved dynamic viscoelasticity of rubber can be produced.

In the rubber composition kneading method, the rotation speed of the rotor can be automatically controlled by a control unit, a target discharge temperature of rubber at the end of the kneading is set, and information on the actually measured temperature in the kneading unit It is preferable that the kneading unit is stirred while the rotational speed is automatically controlled by PID control for setting the measured temperature to the target discharge temperature by the control unit based on the target discharge temperature.

  As described above, in the kneading method of the rubber composition according to the present invention, the reaction end point between the silica and the silane coupling agent is determined based on the difference between the internal humidity and the specified humidity. However, there are variations in the physical properties and water content of the raw rubber, silica and coupling agent, and the reaction end point may be delayed from the normal set time. However, even in such a case, the difference between the internal humidity and the specified humidity is within a desired range by stirring the rubber composition in the kneading part while automatically controlling the rotational speed of the rotor by PID control. The rubber composition can be kept at the target discharge temperature until it becomes inside. As a result, it is possible to prevent the reaction between rubber molecules and the occurrence of network chains (three-dimensional) bonds due to local overheating of the rubber, etc., preventing rubber deterioration, and vulcanized rubber showing good rubber properties The rubber composition used as the raw material can be produced.

  In the kneading method of the rubber composition, the hermetic mixer has an air blow capable of flowing external air from an air inlet formed in a side surface of the casing, and external air is supplied from the air blow to the casing. It is preferable to knead the rubber composition while flowing into the inside. As described above, moisture and alcohol are generated in the closed mixer in proportion to the amount of coupling reaction between silica and the silane coupling agent. According to such a configuration, the inner wall surface of the neck of the closed mixer, etc. Water and / or alcohol condensed on the water can be efficiently discharged to the outside.

  The rubber composition produced by any one of the above rubber composition production methods is excellent in silica dispersibility. When the rubber composition contains a styrene butadiene rubber modified with amine and alkoxysilane, silica, and a silane coupling agent consisting of at least one of Si69, Si75 and protected mercaptosilane, In addition to high dispersibility, various rubber properties are also excellent.

The conceptual diagram which shows the structure of the closed type mixer which concerns on this invention

  In the present invention, a closed mixer is used for kneading the rubber composition. As such a closed mixer, a meshing intermix type mixer, a tangential Banbury type mixer, a pressure kneader, or the like can be used. In particular, a meshing intermix type mixer can be suitably used.

  A preferred embodiment of a hermetic mixer according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a configuration of a closed mixer according to the present invention.

  The hermetic mixer 1 includes a kneading part 4 having a casing 2 and a rotor 3, a neck part 5 located above the kneading part 4 and having a cylindrical space inside, and an upper part on the side surface side of the neck part 5. And a ram 7 that can move up and down in the cylindrical space of the neck portion 5, and a drop door 9 positioned on the lower surface of the kneading portion 4.

  In the present embodiment, a pair of rotors 3 are arranged in the width direction of the kneading unit 4 in the casing 2 of the kneading unit 4 and rotate in predetermined directions using a motor as a power source. At that time, when the rubber composition receives a shearing force in the gap between the rotor 3 and the casing 2 and the ram 7, the coupling reaction between the silica and the silane coupling agent proceeds while the rubber composition is kneaded. . The temperature of the rubber composition at the time of kneading is set to 130 to 180 ° C., for example, and the kneading time is exemplified to be 1 to 15 minutes.

  An opening 2a is provided at the center of the upper surface of the casing 3 of the kneading part 4, and a neck part 5 having a cylindrical space inside is provided above the opening 2a. At the upper part on the side surface side of the neck portion 5, there is provided an inlet 6 through which raw materials rubber, compounding agents such as silica and a silane coupling agent can be charged. Two or more input ports 6 may be provided in order to input the raw rubber and the compounding agent from separate input ports. The raw rubber and the compounding agent charged from the charging port 6 pass through the cylindrical space of the neck portion 5 and are charged into the casing 2 from the opening 2a of the casing 2.

  The ram 7 is formed in a shape capable of closing the opening 2 a of the casing 2, and is provided so as to be movable in the vertical direction in the cylindrical space of the neck portion 5 by a shaft 8 connected to the upper end thereof. The ram 7 can press and press the rubber composition existing in the casing 2 of the kneading part 4 by its own weight or a pressing force from the shaft.

  The drop door 9 located on the lower surface of the casing 2 of the kneading part 4 is closed when the rubber composition is kneaded in the kneading part 4, and is opened after the kneading is finished to discharge the rubber composition downward. Can do.

  A humidity sensor is provided on the side surface of the neck portion 5. In the example shown in FIG. 1, a suction port 10 of a dust collector is provided at the upper side of the side opposite to the charging port 6 provided at the upper side of the neck portion 5, and a humidity sensor (not shown) is provided in the vicinity thereof. Is provided. However, in the present invention, the humidity sensor can be provided at any position on the side surface of the neck portion 5.

  The humidity sensor detects moisture generated in the closed mixer in proportion to the amount of coupling reaction between silica and the silane coupling agent, and provides information on the internal humidity to the experimenter. The internal humidity is higher than the specified humidity measured in the external atmosphere by the amount of water generated. Therefore, by calculating the difference between the internal humidity and the specified humidity, it is possible to grasp how much the coupling reaction between the silica and the silane coupling agent has progressed. That is, the reaction end point between the silica and the silane coupling agent can be determined based on the difference between the internal humidity and the specified humidity. In order to reliably determine the reaction end point of the coupling reaction between silica and the silane coupling agent, and to achieve a good balance between preventing rubber burn and improving silica dispersibility, the difference between the internal humidity and the specified humidity is 25. It is preferable to set the reaction end point to a stage within 20%, and a reaction end point to 20% or less. In order to prevent rubber burn, it is preferable that the reaction end point is set up to a stage where the difference between the internal humidity and the specified humidity is 0% (same) at the latest.

  The hermetic mixer used in the present invention may have an air blow (not shown in FIG. 1) through which external air can flow from an air inlet formed in the side surface of the casing 2. By letting external air flow into the casing 2, water and alcohol can be forcibly discharged from the casing 2, and the water content of the rubber composition after kneading can be reduced. On the other hand, when an exhaust port is formed in the side surface of the casing 2 and water and alcohol in the casing 2 are sucked and discharged, the duct pipe may be clogged with a filler such as silica or water and alcohol.

  In the rubber composition kneading method according to the present invention, it is preferable to stir the rubber composition in the kneading section while automatically controlling the rotational speed of the rotor by PID control. The aspect concerning the following will be described.

  When performing PID control, the rotation speed of the motor that rotates the rotor 3 is adjusted based on a control signal from the control unit 11. The control unit 11 controls the rotational speed of the motor based on the temperature information in the kneading unit 4 sent from the temperature sensor 13. The motor may be configured so that the rotation speed can be freely changed by the control unit 11, for example, an inverter motor.

  More specifically, the rotational speed of the motor is determined from the deviation between the measured temperature Tp in the kneading unit 4 detected by the temperature sensor 13 and the target discharge temperature Ts by the PID calculation processing unit provided inside the control unit 11. PID control based on execution of proportional (P), integral (I), and derivative (D) operations is executed. That is, the PID calculation processing unit calculates a control amount in proportion to a difference (deviation e) between the actual temperature Tp in the kneading unit 4 detected by the temperature sensor 13 and the target discharge temperature Ts (P) operation, Each control amount obtained by an integral (I) operation for calculating a control amount by an integral value obtained by integrating the deviation e in the time axis direction, and a differential (D) operation for calculating a control amount from a gradient of the deviation e, that is, a differential value. The rotation speed of the motor is determined by the sum of the values.

  In the kneading method of the rubber composition according to the present invention, a target discharge temperature of rubber at the end of kneading is set, and based on the information about the measured temperature in the kneading section and the target discharge temperature, the measured temperature is discharged by the control section. The inside of the kneading unit 4 is agitated while automatically controlling the rotation speed by PID control for setting the temperature.

  First, when the rubber composition is charged into the kneading unit 4, the control unit 11 starts PID control on the motor based on the set target discharge temperature value. That is, the rotational speed of the motor is determined based on the control signal from the control unit 11, and thereby the rotational speed of the rotor 3 (that is, the stirring speed) is determined. Information about the target discharge temperature may be given to the control unit 11 side in advance.

  The control unit 11 performs PID control on the rotation speed of the motor until the difference between the internal humidity and the specified humidity falls within a desired range. As for the specific control contents, as described above, the rotational speed is determined based on the deviation between the measured temperature Tp and the target discharge temperature Ts in the kneading section 4 sent from the temperature sensor 13, the integrated value of the deviation, and the differential value of the deviation. Change in small increments.

  The value of the target discharge temperature is preferably set to 180 ° C. or lower in order to prevent the reaction between rubber molecules in the rubber component and the occurrence of network chain (three-dimensional) bonding, and stably maintain the rubber physical properties. 165 ° C. or lower is more preferable. An example of a preferable lower limit of the target discharge temperature is 120 ° C.

  Then, after completion of the kneading, the rubber composition is discharged from the drop door 9. After completion of the kneading, the vulcanizing compounding agent kneading step may be carried out using another mixing and dispersing machine, or the vulcanizing compounding agent kneading is carried out using the mixing and dispersing machine in which the mastication step and the kneading step are carried out. You may implement a process.

  The rubber composition produced by the above production method has a low moisture content and excellent silica dispersibility. Below, the raw material of the rubber composition which can be used by this invention is demonstrated.

  As the raw material rubber to be charged, diene rubber can be preferably used. Examples of the diene rubber include natural rubber (NR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), butadiene rubber (SPB) containing syndiotactic-1,2-polybutadiene, A chloroprene rubber (CR), a nitrile rubber (NBR), etc. are mentioned, These can each be used individually or as a 2 or more types of blend. These exemplified diene rubbers are those having terminal modified as required (for example, terminal modified BR, terminal modified SBR, etc.), or modified to give desired characteristics (for example, modified). NR) can also be used. As this terminal-modified diene rubber, diene rubber whose polymer terminal is modified with various modifiers 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, neodymium 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, molecular weight, etc. are not particularly limited, and the combination of the rubber type and the blend ratio can be appropriately selected depending on the site and use of the rubber composition. 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 What was synthesize | combined using the polymerization catalyst composition containing the metallocene complex as described in -129670 can also be used. Among these diene rubbers, use of BR and / or SBR is preferable, use of SBR is more preferable, and 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, etc. used for usual rubber reinforcement are used. Of these, wet silica is preferable. It is preferable that the compounding quantity of a silica is 20-120 mass parts with respect to 100 mass parts of raw rubber, and it is more preferable that it is 40-100 mass parts.

  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 Degussa), bis (3-triethoxysilylpropyl) disulfide (for example, “Si75” manufactured by Degussa), bis (2-tri Sulfide silanes such as ethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltri Mercaptosilanes such as methoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane, 3-octanoylthio-1- Examples thereof include protected mercaptosilanes such as propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. 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 5-15 mass parts.

  A typical example of the vulcanizing agent is sulfur. Sulfur should just be normal sulfur for rubber | gum, For example, powder sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur etc. can be used.

  In the present invention, the rubber composition contains at least a compounding agent other than raw rubber, silica, silane coupling agent and vulcanizing agent, such as filler, zinc oxide, stearic acid, vulcanization accelerator, vulcanization accelerator, Compounding agents usually used in the rubber industry such as vulcanization retarders, anti-aging agents, reversion inhibitors, softeners such as waxes and oils, processing aids, etc. are appropriately blended within a range that does not impair the effects of the present invention. Can be used.

  The filler means an inorganic filler usually used in the rubber industry, such as carbon black, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide. Among the inorganic fillers, carbon black can be particularly preferably used.

  As carbon black, for example, conductive carbon black such as acetylene black and ketjen black can be used in addition to carbon black used in ordinary rubber industry such as SAF, ISAF, HAF, FEF, and GPF. The carbon black may be a granulated carbon black or a non-granulated carbon black granulated in the normal rubber industry in consideration of its handleability.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate.

  As an anti-aging agent, an aromatic amine-based anti-aging agent, an amine-ketone-based anti-aging agent, a dithiocarbamate-based anti-aging agent, a thiourea-based anti-aging agent, etc., which are usually used for rubber in addition to a phenol-based anti-aging agent May be used as needed.

(Raw materials used)
a) Rubber component (the total amount is 100 parts by mass)
Modified styrene butadiene rubber (modified SBR) 100 parts by mass: HPR340 manufactured by JSR Corporation (modified S-SBR, amount of bound styrene: 10% by mass, modified with amine and alkoxyl silane)
b) 20 parts by mass of carbon black (HAF-HS (N339)): Seast KH manufactured by Tokai Carbon Co., Ltd.
c) Silica 70 parts by mass: Tosoh Silica Industry Co., Ltd. “Nipseal AQ”
d) a silane coupling agent 7 parts: protected _{mercaptosilane: (C n H 2n + 1} O) 3 Si-C m H 2m -S-CO-C k H 2k + 1 with a coupling agent represented by (n = 2, m = 3, k = 7), “NXT” made by Momentive Performance Materials
e) Oil 40 parts by mass: Japan Energy Corporation “Process X-140”
f) 2 parts by mass of stearic acid: “stearic acid” manufactured by NOF Corporation
g) 3 parts by mass of zinc oxide: “Zinc oxide 2 types” manufactured by Mitsui Mining & Smelting Co., Ltd.
h) Anti-aging agent 2 parts by mass: “Antigen 6C” manufactured by Sumitomo Chemical Co., Ltd.
i) 2 parts by weight of wax: “paraffin wax 135” manufactured by Nippon Seiwa Co., Ltd.
j) 2.1 parts by mass of sulfur: “oil-treated 150 mesh powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
k) 1.5 parts by mass of vulcanization accelerator: “Noxeller CZ-G” manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1-2
The reaction between silica and the silane coupling agent based on the difference between the internal humidity measured over time by the humidity sensor and the specified humidity measured in the external atmosphere using the hermetic mixer shown in FIG. The end point was determined, and the kneading was finished when the reaction end point was reached (humidity control). In Examples 1 and 2, the target discharge temperature was set to 160 ° C., and the rotation speed of the rotor was set to 100 RPM until such temperature was reached. Then, after reaching the target discharge temperature, the rotational speed of the rotor was automatically controlled by PID control until reaching the reaction end point. Further, a hermetic mixer having an air blow capable of flowing in external air from an air inlet formed in the side surface of the casing 2 was used. After reaching the reaction end point, the rubber composition was discharged from the drop door. The rubber composition after kneading was vulcanized under the following vulcanization conditions and evaluated. The results are shown in Table 1.

Comparative Example 1
The rubber composition was kneaded based on normal temperature control instead of humidity control in Examples 1 and 2. Specifically, the target discharge temperature was set to 160 ° C., and the rotational speed of the rotor was set to 100 RPM until such temperature was reached. After reaching the target discharge temperature, the rubber composition was discharged from the drop door. In addition, as an airtight mixer, what does not have an air blow was used. The rubber composition after kneading was vulcanized under the following vulcanization conditions and evaluated. The results are shown in Table 1.

Comparative Examples 2-3
The rubber composition was kneaded based on normal time management instead of humidity management. Specifically, the mixing time is set in advance, the rotor speed is set to 100 RPM until the target discharge temperature reaches 160 ° C., and after reaching the target discharge temperature, the PID control is performed until the reaction end point is reached. The rotor rotation speed was automatically controlled. Further, a hermetic mixer having an air blow capable of flowing in external air from an air inlet formed in the side surface of the casing 2 was used. After reaching the reaction end point, the rubber composition was discharged from the drop door. Table 1 shows the difference between the internal humidity when the set mixing time is reached and the rubber composition is produced from the drop door and the specified humidity measured in the external atmosphere. Further, the rubber composition after kneading was vulcanized under the following vulcanization conditions and evaluated. The results are shown in Table 1.

[Moisture content in rubber]
Index evaluation was performed with the measurement result of the moisture content of the rubber composition obtained in Comparative Example 1 as 100. The smaller the value, the lower the moisture content. The results are shown in Table 1.

[Dynamic viscoelasticity]
Vulcanized at 160 ° C. for 30 minutes, and tan δ at a temperature of 70 ° C./frequency of 10 Hz, initial strain of 10%, and dynamic strain of 2% using a Toyo Seiki viscoelasticity tester according to JIS K6394 An index evaluation was performed with the measurement result of Comparative Example 1 taken as 100. The smaller the value, the better the dynamic viscoelasticity. The results are shown in Table 1.

[Pain effect]
From the maximum shear force when the strain is changed from 0.5 to 45% using RPA2000 manufactured by Alpha Technologies and vulcanized rubber vulcanized at 160 ° C for 30 minutes at a temperature of 60 ° C and a frequency of 1.667 Hz. The value obtained by subtracting the minimum shear force was measured, and index evaluation was performed with the measurement result of Comparative Example 1 as 100. The smaller the value, the better the dispersibility of the filler. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Sealing mixer 2 Casing 3 Rotor 4 Kneading part 5 Sheet-like rubber molding apparatus 6 Neck part 7 Ram 8 Shaft 9 Drop door

Claims (6)

A method for kneading a rubber composition containing at least raw rubber, silica and a silane coupling agent,
A kneading part having a casing and a rotor, kneading the rubber composition; a neck part located above the kneading part and having a cylindrical space inside; and provided on an upper side of the neck part. Use a closed mixer equipped with an inlet and a humidity sensor provided on the side of the neck,
Based on the difference between the internal humidity measured over time by the humidity sensor and the specified humidity measured in an external atmosphere, the reaction end point of the silica and the silane coupling agent was determined, and the reaction end point was reached. A method of kneading a rubber composition, characterized in that kneading is terminated.   The method for kneading a rubber composition according to claim 1, wherein a reaction end point is a stage where a difference between the internal humidity and the specified humidity is within 25%. The rotor is capable of automatic control of the rotation speed by the control unit,
PID control for setting a target discharge temperature of rubber at the end of the kneading and setting the measured temperature to the target discharge temperature by the control unit based on the information on the measured temperature in the kneading unit and the target discharge temperature The method for kneading a rubber composition according to claim 1 or 2, wherein the inside of the kneading part is stirred while automatically controlling the rotation speed.   The closed mixer has an air blow capable of flowing external air from an air inlet formed in a side surface of the casing, and the rubber composition while allowing external air to flow into the casing from the air blow The method for kneading a rubber composition according to claim 1, wherein kneading is carried out.   The rubber composition manufactured by the kneading | mixing method of the rubber composition in any one of Claims 1-4.   The rubber composition according to claim 5, comprising a styrene butadiene rubber modified with an amine and an alkoxysilane, silica, and a silane coupling agent comprising at least one of Si69, Si75 and protected mercaptosilane.

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