JP2020100784A - Method for producing rubber composition and method for manufacturing tire - Google Patents

Abstract

To provide a method for producing a rubber composition, capable of reacting a silane coupling agent with silica well.SOLUTION: The method for producing a rubber composition according to the present disclosure includes the steps of: kneading at least a rubber, silica, and a silane coupling agent while controlling a kneading temperature so as to suppress a reaction between the silica and the silane coupling agent; and kneading them while controlling the kneading temperature so as to advance the reaction between the silica and the silane coupling agent. Furthermore, the silica contains a first silica having a specific surface area measured by a nitrogen adsorption method of more than 200 m2/g.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a method for producing a rubber composition and a method for producing a tire.

Since silica used as a reinforcing filler for rubber has silanol groups, it tends to aggregate due to hydrogen bonds. Therefore, it is not easy to disperse silica well. In particular, it is difficult to disperse silica well when it is highly filled with silica or when silica having a small particle size is used.

Silane coupling agents are commonly used to improve the dispersibility of silica. The silane coupling agent not only can react with silanol groups on the surface of silica, but also can react with a rubber polymer to bond silica and the rubber polymer.

By well dispersing silica and reacting silica with a silane coupling agent well, low heat buildup, which is an important performance for tires, and braking performance on wet road surfaces (hereinafter referred to as "wet road surface braking performance"). ) Can be improved.

JP, 2013-18890, A JP, 2010-216952, A

An object of the present disclosure is to provide a method for producing a rubber composition capable of reacting silica with a silane coupling agent well.

The method for producing a rubber composition according to the present disclosure includes a step of kneading at least rubber, silica and a silane coupling agent while controlling the kneading temperature so that the reaction of silica and the silane coupling agent is suppressed. And a step of kneading while controlling the kneading temperature so that the reaction of the silica and the silane coupling agent proceeds. Moreover, the silica contains the first silica having a specific surface area of more than 200 m ² /g by the nitrogen adsorption method.

The method for producing a tire according to the present disclosure includes a step of producing a rubber composition by the method of producing a rubber composition according to the present disclosure, and a step of producing an unvulcanized tire using the rubber composition.

1 is a conceptual diagram showing a configuration of a closed kneader that can be used in the first embodiment.

A method for producing a rubber composition according to an aspect of the present disclosure includes at least a rubber, a silica, and a silane coupling agent so that a reaction of the silica and the silane coupling agent (hereinafter, referred to as “silane reaction”) is suppressed. , A step of kneading while controlling the kneading temperature (hereinafter referred to as “step K1”), and a step of kneading while controlling the kneading temperature so that the silane reaction proceeds (hereinafter referred to as “step K3”). .) and. The method for producing the rubber composition of the present embodiment may include a step of kneading while increasing the kneading temperature (hereinafter, referred to as “step K2”) between step K1 and step K3. .. Moreover, in the method for producing the rubber composition of the present aspect, the silica contains the first silica having a specific surface area of more than 200 m ² /g by the nitrogen adsorption method.

In the method for producing the rubber composition according to this embodiment, silica can be well reacted with a silane coupling agent. The mechanism leading to such an effect is presumed as follows.

At least the rubber, silica and silane coupling agent are kneaded while controlling the kneading temperature so that the silane reaction (reaction of silica and silane coupling agent) is suppressed. The silica can be effectively dispersed. Therefore, a state in which silica is dispersed can be created before the silane reaction proceeds actively. After that, since the kneading is performed while controlling the kneading temperature so that the silane reaction proceeds, the silane reaction can be actively promoted in a state where silica is dispersed. As a result, it is considered that the silane coupling agent reacts well with silica.

Moreover, since the silica contains the first silica having a specific surface area of more than 200 m ² /g, many silane coupling agents can be reacted (the reaction rate of the silane coupling agent can be increased). Therefore, the silane coupling agent can be better reacted with silica.

The method for producing the rubber composition of this embodiment can also improve the dispersion of silica. It is considered that this is because the method for producing the rubber composition of the present embodiment can effectively react the silica with the silane coupling agent, so that the cohesive force of the silica can be effectively reduced.

The method for producing the rubber composition of the present aspect can also improve the wet road surface braking property of the tire. It is considered that this is because the method for producing the rubber composition of the present embodiment can improve the silica dispersion.

The method for producing the rubber composition of the present aspect can also improve the low heat buildup of the tire. It is considered that this is because the method for producing the rubber composition of the present embodiment can improve the silica dispersion.

The step K1 may include kneading so that the kneading temperature is kept constant. According to this configuration, since it is possible to suppress an increase in the kneading temperature due to the progress of the kneading, it is possible to effectively suppress the silane reaction. Therefore, silica can be more effectively dispersed in the step K1.

The step K3 may include kneading so that the kneading temperature is kept constant. According to this configuration, an increase in the kneading temperature due to the progress of the kneading can be suppressed, so that the silane reaction can be promoted while suppressing gelation.

In step K1, kneading may be performed by a closed kneader, and in step K3, kneading may be performed by a closed kneader.

<<Embodiment 1>>
From here, Embodiment 1 which is an example of this aspect is demonstrated.

<1. Closed kneader>
First, a closed type kneader that can be used in the first embodiment will be described.

As shown in FIG. 1, the closed kneader 1 includes a kneading section 4 having a casing 2 and a rotor 3, a neck section 5 located above the kneading section 4 and having a cylindrical space inside, and a neck section. 5, a ram 7 that can move up and down in the cylindrical space of the neck portion 5, and a drop door 9 located on the lower surface of the kneading portion 4.

An opening 2a is provided at the center of the upper surface of the casing 2. A neck portion 5 having a cylindrical space inside is provided above the opening 2a. On the side surface of the neck portion 5, a charging port 6 through which rubber and a compounding agent can be charged is provided. Two or more charging ports 6 may be provided for charging the rubber and the compounding agent through separate charging ports. The rubber and the compounding agent introduced from the introduction port 6 are introduced into the casing 2 through the opening 2a of the casing 2 through the tubular space of the neck portion 5.

The ram 7 has a shape capable of closing the opening 2a of the casing 2. The ram 7 can move up and down in the tubular space of the neck portion 5 by the shaft 8 connected to the upper end thereof. The ram 7 can press and press the rubber existing in the casing 2 by its own weight or the pressing force from the shaft 8.

The drop door 9 is closed during kneading. After the kneading is completed, the drop door 9 is opened.

The rotation speed of a motor (not shown) that rotates the rotor 3 is adjusted based on a control signal from the control unit 11. The control unit 11 controls the rotation speed of the motor based on the temperature information (specifically, the measured temperature Tp) in the kneading unit 4 sent from the temperature sensor 13. The rotation speed of the motor can be freely changed by the control unit 11. The motor can be, for example, an inverter motor.

In order to determine the rotation speed of the motor, the PID calculation processing unit provided inside the control unit 11 is proportional to the deviation (from the difference between the actual measurement temperature Tp in the kneading unit 4 detected by the temperature sensor 13 and the target temperature Ts ( P), integration (I) and differentiation (D). Specifically, 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, and the integral that integrates the deviation e in the time axis direction. The rotation speed of the motor is calculated by the sum of the control amounts obtained by the integral (I) operation for calculating the control amount by the value and the derivative (D) operation for calculating the control amount from the gradient of the change in the deviation e, that is, the differential value. To decide. PID is an abbreviation for Proportional Integral Differential.

<2. Each step of the method for producing a rubber composition>
Next, some of the steps included in the method for producing a rubber composition according to the first embodiment will be described.

The method for producing a rubber composition according to the first embodiment includes a step of producing a rubber mixture (hereinafter referred to as “step S1”) and a step of kneading at least the rubber mixture and a vulcanizing compounding agent to obtain a rubber composition. (Hereinafter, referred to as “process S2”).

<2.1. Step S1 (step of producing a rubber mixture)>
Step S1 is a step K1 of kneading at least rubber, silica and a silane coupling agent while controlling the kneading temperature so that the silane reaction (reaction of silica and the silane coupling agent) is suppressed, and then, It includes a step K2 of kneading while increasing the kneading temperature, and then a step K3 of kneading while controlling the kneading temperature so that the silane reaction proceeds.

<2.1.1. Step K1 (step of kneading so as to suppress silane reaction)>
In step K1, at least rubber, silica and a silane coupling agent are charged into the closed kneading machine 1, and the kneading temperature is controlled so that the silane reaction (reaction of silica and the silane coupling agent) is suppressed. Knead.

In step K1, it is preferable to add rubber and the like (at least rubber, silica and a silane coupling agent) to the closed kneading machine 1 so that the fill factor is 60% or less. When it is 60% or less, the object to be kneaded can be effectively sheared. Therefore, silica can be effectively dispersed. The fill factor is preferably 50% or more, more preferably 52% or more, still more preferably 54% or more. When it is 50% or more, when it is desired to raise the kneading temperature to a predetermined temperature, the kneading temperature can be raised without any problem.

The fill factor is calculated by the following formula.
Fill factor=(volume of kneading target/volume of kneading chamber of closed kneading machine 1)×100
In this equation, the volume of the object to be kneaded can be expressed in cubic decimeters. The volume of the kneading target can be calculated based on the mass of the kneading target and the density of the kneading target. Here, the mass of the object to be kneaded can be the total of the mass of the compounding agent excluding the vulcanizing compounding agent (for example, sulfur and the vulcanization accelerator) and the mass of the rubber. In this formula, the volume of the kneading chamber can also be expressed in cubic decimeters. The capacity of the kneading chamber is not particularly limited. The capacity of the kneading chamber can be, for example, 150 dm ³ or more and 450 dm ³ or less. In addition, 1 cubic decimeter corresponds to 1 L.

Examples of the rubber include natural rubber, polyisoprene rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), nitrile rubber, chloroprene rubber and the like. From these, one or any combination can be selected and used. The rubber is preferably a diene rubber.

Modified rubber may be used as the rubber. Examples of the modified rubber include modified SBR and modified BR. The modified rubber can have a functional group containing a hetero atom. The functional group may be introduced at the end of the polymer chain or may be introduced in the polymer chain, but is preferably introduced at the end. Examples of the functional group include an amino group, an alkoxyl group, a hydroxyl group, a carboxyl group, an epoxy group, a cyano group, and a halogen group. Of these, an amino group, an alkoxyl group, a hydroxyl group and a carboxyl group are preferable. The modified rubber can have at least one of the exemplified functional groups. Examples of the amino group include a primary amino group, a secondary amino group and a tertiary amino group. Examples of the alkoxyl group include a methoxy group, an ethoxy group, a propoxy group and a butoxy group. The functional groups illustrated interact with the silanol groups of silica (Si-OH). Here, the interaction means, for example, a chemical bond or a hydrogen bond by a chemical reaction with the silanol group of silica. The amount of the modified rubber in 100% by mass of the rubber used in the step K1 may be 10% by mass or more, 20% by mass or more, and 30% by mass or more. The amount of the modified rubber in 100% by mass of the rubber used in the step K1 may be 90% by mass or less, 80% by mass or less, or 70% by mass or less.

As the silica, at least first silica (silica having a specific surface area of 200 m ² /g by the nitrogen adsorption method) and second silica (silica having a specific surface area of 200 m ² /g or less by the nitrogen adsorption method) are used.

The specific surface area of the nitrogen adsorption method on the first silica exceeds 200 m ² /g. The specific surface area of the first silica is preferably 210 m ² /g or more, more preferably 220 m ² /g or more. The specific surface area of the first silica may be, for example, 300 m ² /g or less, 280 m ² /g or less, or 260 m ² /g or less.

On the other hand, the specific surface area of the second silica in the nitrogen adsorption method is 200 m ² /g or less. The specific surface area of the second silica may be, for example, 190 m ² /g or less, or 180 m ² /g or less. The specific surface area of the second silica may be, for example, 80 m ² /g or more, 120 m ² /g or more, 140 m ² /g or more, and 160 m ² /g or more. May be.

The specific surface area of silica is measured according to the multipoint nitrogen adsorption method (BET method) described in JIS K-6430.

Examples of the silica such as the first silica and the second silica include wet silica and dry silica. Of these, wet silica is preferable. Wet silica may include precipitated silica.

The compounding ratio of the first silica to the second silica (that is, the amount of the first silica/the amount of the second silica) is preferably 0.6 or more, more preferably 1.0 or more, still more preferably 1.4 or more. is there. When the compounding ratio is 0.6 or more, the effect of improving the reaction rate of the silane coupling agent may be good. The blending ratio may be 2.0 or more, 3.0 or more, and 4.0 or more. On the other hand, this blending ratio is preferably 7.0 or less, more preferably 6.0 or less, further preferably 5.5 or less, and further preferably 5.0 or less. When the compounding ratio is 7.0 or less, the bulk of silica can be prevented from becoming excessively high. Therefore, the object to be kneaded can be effectively sheared.

The amount of the first silica in 100% by mass of silica may be 10% by mass or more, 30% by mass or more, 50% by mass or more, and 70% by mass or more. It may be 90% by mass or more.

In step K1, the amount of silica is preferably 10 parts by mass or more, and more preferably 20 parts by mass or more with respect to 100 parts by mass of rubber. The amount of silica may be 30 parts by mass or more, 40 parts by mass or more, and 60 parts by mass or more. The amount of silica is preferably 160 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 120 parts by mass or less with respect to 100 parts by mass of rubber. The amount of silica may be 100 parts by mass or less, or 90 parts by mass or less.

Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, and bis(4-triethoxysilyl). Butyl) disulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, sulfide silane such as bis(2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyl Examples thereof include mercaptosilanes such as dimethoxysilane, mercaptopropyldimethylmethoxysilane and mercaptoethyltriethoxysilane, and protected mercaptosilanes such as 3-octanoylthio-1-propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. From these, one or any combination can be selected and used.

In step K1, the amount of the silane coupling agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, relative to 100 parts by mass of silica. The upper limit of the amount of silane coupling agent is, for example, 20 parts by mass or 15 parts by mass with respect to 100 parts by mass of silica.

In step K1, carbon black, an antioxidant, stearic acid, wax, zinc oxide, oil and the like can be kneaded together with the rubber, silica and silane coupling agent. From these, one or any combination can be selected and used.

As the carbon black, for example, furnace black such as SAF, ISAF, HAF, FEF and GPF, as well as conductive carbon black such as acetylene black and Ketjen black can be used. The carbon black may be a granulated carbon black granulated in consideration of its handling property or an ungranulated carbon black. One or more of these can be used.

As anti-aging agents, aromatic amine anti-aging agents, amine-ketone anti-aging agents, monophenol anti-aging agents, bisphenol anti-aging agents, polyphenol anti-aging agents, dithiocarbamate anti-aging agents, thiourea An antiaging agent etc. can be mentioned. As the antiaging agent, one or any combination can be selected from these and used.

In step K1, kneading is performed so that the kneading temperature is kept constant. The phrase "kneading temperature is kept constant" includes that the kneading temperature is kept within a certain range. In the step K1, specifically, the measured temperature Tp is kneaded so as to be maintained at the target temperature Ts. At this time, the measured temperature Tp can be kept within plus or minus 5° C. of the target temperature Ts. The target temperature Ts may be less than 140° C., 138° C. or less, 135° C. or less, 132° C. or less, and 130° C. or less. The target temperature Ts is preferably 100° C. or higher, more preferably 110° C. or higher, even more preferably 115° C. or higher, even more preferably 120° C. or higher. If it is too low, it tends to take time to disperse the silica. The target temperature Ts can be appropriately set in consideration of the composition, particularly the type of the silane cup agent.

In step K1, kneading is performed for 10 seconds or more so that the kneading temperature is maintained within a certain range. It is preferably 20 seconds or longer, more preferably 30 seconds or longer, still more preferably 40 seconds or longer. It may be 1000 seconds or less, 800 seconds or less, 600 seconds or less, 400 seconds or less, 200 seconds or less, 100 seconds or less. May be.

The kneading temperature is maintained by adjusting the rotation speed of the rotor 3. Specifically, the kneading temperature is maintained by adjusting the rotation speed of the rotor 3 by PID control. Here, the rotation speed of the rotor 3 is adjusted by PID control for setting the measured temperature Tp to the target temperature Ts. The PID control may be started from the beginning of kneading, or may be started when the measured temperature Tp reaches a predetermined temperature.

<2.1.2. Process K2 (process of kneading while increasing kneading temperature)>
In step K2, kneading is performed while increasing the kneading temperature. In step K2, the kneading temperature is raised to a temperature at which the silane reaction actively proceeds (for example, 140° C. or higher). Specifically, the kneading temperature is raised to the target temperature Ts of step K3.

<2.1.3. Process K3 (process of kneading so that silane reaction proceeds)>
In step K3, kneading is performed while controlling the kneading temperature so that the silane reaction (reaction of silica and silane coupling agent) proceeds.

In step K3, kneading is performed so that the kneading temperature is kept constant. The phrase "kneading temperature is kept constant" includes that the kneading temperature is kept within a certain range. In step K3, specifically, the measured temperature Tp is kneaded so as to be maintained at the target temperature Ts. At this time, the measured temperature Tp can be kept within plus or minus 5° C. of the target temperature Ts. The target temperature Ts may be 140°C or higher, 142°C or higher, 145°C or higher, 148°C or higher, and 150°C or higher. If it is too low, it will tend to take too long to proceed with the silane reaction. The target temperature Ts is preferably 170° C. or lower, more preferably 165° C. or lower, further preferably 160° C. or lower, further preferably 155° C. or lower, still more preferably 153° C. or lower. If it is too high, gels may form.

In step K3, kneading is performed for 20 seconds or more so that the kneading temperature is maintained within a certain range. It is preferably 40 seconds or longer, more preferably 60 seconds or longer, still more preferably 80 seconds or longer. It may be 2000 seconds or less, 1500 seconds or less, 1000 seconds or less, 500 seconds or less, 300 seconds or less, 200 seconds or less. May be.

The kneading temperature is maintained by adjusting the rotation speed of the rotor 3 as in the step K1.

Then, if necessary, the kneading is continued to a predetermined discharge temperature, the drop door 9 is opened, and the rubber mixture is discharged.

<2.1.4. Other>
The rubber mixture can be further kneaded if necessary. For example, silica and a silane coupling agent can be added to the rubber mixture, if necessary, and further kneaded. The silica added at this stage may be the same as or different from the silica added in the step K1. The silane coupling agent added at this stage may be the same as or different from the silane coupling agent added in the step K1.

The rubber mixture can be obtained by the above procedure.

<2.2. Step S2 (step of kneading a rubber mixture and a vulcanizing compounding agent to obtain a rubber composition)>
In step S2, at least the rubber mixture and the vulcanizing compounding agent are kneaded to obtain a rubber composition. Examples of the vulcanizing compounding agent include vulcanizing agents such as sulfur and organic peroxides, vulcanization accelerators, vulcanization accelerating aids, and vulcanization retarders. The vulcanizing compounding agent can be used by selecting one or any combination thereof. Examples of sulfur include powdered sulfur, precipitated sulfur, insoluble sulfur, and highly dispersible sulfur. Sulfur can be used by selecting one or any combination from these. As a vulcanization accelerator, a sulfenamide vulcanization accelerator, a thiuram vulcanization accelerator, a thiazole vulcanization accelerator, a thiourea vulcanization accelerator, a guanidine vulcanization accelerator, a dithiocarbamate vulcanization accelerator And so on. As the vulcanization accelerator, one or any combination can be selected and used from these. The kneading can be performed with a kneader. Examples of the kneader include a closed kneader and an open roll. Examples of the closed kneader include Banbury mixer and kneader.

In the rubber composition, the amount of silica is preferably 10 parts by mass or more, and more preferably 20 parts by mass or more with respect to 100 parts by mass of rubber. The amount of silica may be 30 parts by mass or more, 40 parts by mass or more, and 60 parts by mass or more. The amount of silica is preferably 160 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 120 parts by mass or less with respect to 100 parts by mass of rubber. The amount of silica may be 100 parts by mass or less, or 90 parts by mass or less.

In the rubber composition, the amount of the silane coupling agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of silica. The upper limit of the amount of silane coupling agent is, for example, 20 parts by mass or 15 parts by mass with respect to 100 parts by mass of silica.

The rubber composition may further include carbon black, an antioxidant, stearic acid, wax, zinc oxide, oil, sulfur, a vulcanization accelerator and the like. The rubber composition may include one or any combination thereof. The amount of sulfur is preferably 0.5 to 5 parts by mass in terms of sulfur content with respect to 100 parts by mass of rubber. The amount of the vulcanization accelerator is preferably 0.1 part by mass to 5 parts by mass with respect to 100 parts by mass of rubber.

The rubber composition can be used for producing a tire. Specifically, it can be used for producing a tire member constituting a tire. For example, the rubber composition can be used for producing tread rubber, sidewall rubber, chafer rubber, bead filler rubber and the like. The rubber composition can be used to make one or any combination of these tire components.

<3. Each step of tire manufacturing method>
Next, some of the steps included in the tire manufacturing method according to the first embodiment will be described. Among these steps, the step of producing the rubber composition has already been described.

The tire manufacturing method according to the first embodiment includes a step of manufacturing an unvulcanized tire using the rubber composition. This step includes producing a tire member including the rubber composition, and producing an unvulcanized tire including the tire member. Examples of tire members include tread rubber, sidewall rubber, chaeher rubber, and bead filler rubber. Of these, tread rubber is preferable.

The tire manufacturing method according to the first embodiment may further include a step of vulcanizing and molding an unvulcanized tire. The tire obtained by the method of the first embodiment can be a pneumatic tire.

<Various changes can be made to the first embodiment>
Various modifications can be added to the method for manufacturing the rubber composition and the method for manufacturing the tire according to the first embodiment. For example, one or more can be selected from the following modified examples to change the first embodiment.

In the above-described first embodiment, the configuration in which the first silica and the second silica are used as the silica has been described. However, the first embodiment is not limited to this configuration. For example, only the first silica may be used as the silica.

In Embodiment 1 described above, the configuration in which the kneading temperature is controlled by the rotation speed of the rotor 3 in the step K1 has been described. However, the first embodiment is not limited to this configuration. For example, the kneading temperature may be controlled by the temperature of the heating/cooling medium flowing through the jacket (not shown) of the closed kneading machine 1, or the kneading temperature may be controlled by the pressing force of the ram 7. The kneading temperature may be controlled by any combination of these.

In the above-described first embodiment, the configuration in which the kneading temperature is controlled based on the PID control in the step K1 has been described. However, the first embodiment is not limited to this configuration. The kneading temperature may be controlled based on a control method other than the PID control.

In Embodiment 1 described above, the configuration in which the kneading temperature is controlled by the rotation speed of the rotor 3 in the step K3 has been described. However, the first embodiment is not limited to this configuration. For example, the kneading temperature may be controlled by the temperature of the heating/cooling medium flowing through the jacket (not shown) of the closed kneading machine 1, or the kneading temperature may be controlled by the pressing force of the ram 7. The kneading temperature may be controlled by any combination of these.

In Embodiment 1 described above, the configuration in which the kneading temperature is controlled based on the PID control in the step K3 has been described. However, the first embodiment is not limited to this configuration. The kneading temperature may be controlled based on a control method other than the PID control.

In the above-described first embodiment, the configuration in which the rubber mixture and the vulcanizing compounding agent are kneaded to obtain the rubber composition has been described. However, the first embodiment is not limited to this configuration. For example, the rubber mixture may be considered a rubber composition.

Examples of the present disclosure will be described below.

The raw materials and chemicals used in the examples are shown below.
SBR1 "SBR1502" made by JSR SBR2 "SBR1723" (oil content 37.5% by mass) made by JSR NR RSS#3
Carbon black "Seast KH" manufactured by Tokai Carbon Co., Ltd. Silica 1 "9100GR" (BET = 235m ² / g) Evonik Co. Silica 2 "VN3" (BET = 180m ² / g) Evonik Ltd. Oil "Process NC-140" JX Nikko Nisseki Energy's silane coupling agent “Si75” Degussa's anti-aging agent “Nocrac 6C” Ouchi Shinko Chemical Co., Ltd. zinc oxide “Zinc oxide 2” Mitsui Mining & Smelting wax “OZOACE0355” Nippon Seiro Manufactured by Stearic acid “Industrial stearic acid” Kao manufactured by Sulfur “5% oil-treated powdered sulfur” Tsurumi Chemical Co., Ltd. Vulcanization accelerator “Nocceller NS-P” manufactured by Ouchi Shinko Chemical Co., Ltd. And in Table 2, the mass part of SBR2 is shown based on the amount of net rubbers. That is, when SBR2 is 30 parts by mass in the table below, the amount of oil is not included in the 30 parts by mass.

Calculation of fill factor The fill factor was calculated by the following formula.
Fill factor=(volume of kneading object/volume of kneading chamber of B type Banbury mixer)×100
The volume of the kneading target was determined based on the mass of the kneading target and the density of the kneading target. Here, the mass of the object to be kneaded was determined by summing the mass of the compounding agent excluding sulfur and the vulcanization accelerator and the mass of the rubber. The capacity of the kneading chamber was 260 cubic decimeters.

Preparation of Unvulcanized Rubber in Comparative Example 1 According to Table 1, a compounding agent excluding sulfur and a vulcanization accelerator and rubber were put into a B-type Banbury mixer, kneaded without PID control, and discharged at 160° C. And a rubber mixture was obtained. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation of Unvulcanized Rubber in Comparative Example 2 and Comparative Example 4 According to Table 1, a compounding agent excluding sulfur and a vulcanization accelerator and rubber were put into a B-type Banbury mixer, and kneaded under PID control to obtain 160. Discharged at ℃, to obtain a rubber mixture. That is, the compounding agent and the rubber were kneaded at the target temperature Ts=150° C. and discharged at 160° C. to obtain a rubber mixture. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation of Unvulcanized Rubber in Examples 1, 2 and 4 and Comparative Example 3 According to Table 1, a compounding agent excluding sulfur and a vulcanization accelerator and rubber were charged into a B-type Banbury mixer, and PID control was performed. The mixture was kneaded and discharged at 160° C. to obtain a rubber mixture. That is, the compounding agent and the rubber were kneaded at the target temperature Ts=130° C., then at the target temperature Ts=150° C., and discharged at 160° C. to obtain a rubber mixture. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation of Unvulcanized Rubber in Example 3 According to Table 1, a compounding agent excluding sulfur and a vulcanization accelerator and rubber were put into a B-type Banbury mixer, kneaded under PID control, and discharged at 165°C. , A rubber mixture was obtained. That is, the compounding agent and the rubber were kneaded at the target temperature Ts=120° C., then at the target temperature Ts=160° C., and discharged at 165° C. to obtain a rubber mixture. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation of Vulcanized Rubber Unvulcanized rubber was vulcanized at 150° C. for 30 minutes to obtain a vulcanized rubber.

Reaction Rate of Silane Coupling Agent The reaction rate of the silane coupling agent was determined according to the method described in JP 2010-216952A. Specifically, first, a rubber mixture (that is, a mixture containing no sulfur and a vulcanization accelerator) is drawn into a sheet having a thickness of 1 mm or less, and 1.00 g (m ₀ =1. A sample of 00g) was cut out. Then, Soxhlet extraction was performed for 8 hours with acetone, the sample after extraction was vacuum dried at 30° C. for 5 hours, and the mass m of the sample after extraction was measured. Then, the sulfur content S (sulfur concentration: mass %) contained in the sample after extraction was measured by an ion chromatograph “ICS-1500” manufactured by Nippon Dionex. Further, a rubber mixture (rubber mixture containing no silane coupling agent) was prepared by the same method except that the silane coupling agent was not added. With respect to the rubber mixture containing no silane coupling agent, the sample was cut out and the sulfur content S 2 _O (mass %) contained in the sample after extraction was measured by the same method. Then, the reaction rate of the silane coupling agent was determined by the following formula.
The reaction rate _{(%) = {(S-} S O) / S r} × (m / m 0) × 100 ... (I)
S is the sulfur content S (mass %) contained in the sample after extraction. S 2 _O is the sulfur content (mass %) contained in the sample after extraction derived from the rubber mixture containing no silane coupling agent. S _r is the sulfur content (mass %) due to the silane coupling agent contained in the sample before extraction, which is calculated from the blending amount of the silane coupling agent. m ₀ is the mass of the sample before extraction. m is the mass of the sample after extraction.

Dispersibility A test piece of vulcanized rubber was measured using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd. under conditions of temperature 60° C., frequency 10 Hz, static strain 10% and dynamic strain 0.1% and 10%. The storage elastic moduli (E'(0.1) and E'(10)) were measured and the Payne effect (δE'=E'(0.1)-E'(10)) was calculated. The result of each example is shown in Table 1 by an index with the Pain effect of Comparative Example 1 being 100. The larger the index, the better the dispersibility of the filler.

Wet road braking property Using a Lupke type impact resilience tester, the impact resilience (%) was measured at 23° C. according to JIS K6255. Table 1 shows the reciprocal of each example (reciprocal of impact resilience) with an index with the reciprocal of impact resilience in Comparative Example 1 being 100. The larger the index, the better the wet road braking performance.

Fuel economy The tan δ of the vulcanized rubber was measured according to JIS K-6394. The tan δ was measured using a dynamic viscoelasticity measuring device manufactured by Ueshima Seisakusho under the conditions of frequency 50 Hz, dynamic strain 1.0%, temperature 50° C., static strain (initial strain) 10%. Table 1 shows the tan δ of each example, which is an index with tan δ of Comparative Example 1 as 100. The larger the index, the lower the tan δ and the better the fuel economy.

In Table 1 and Table 2 described later, the first temperature control means PID control started when the measured temperature Tp reaches the target temperature Ts. The first temperature control time is a time (length of time) when the first temperature control is performed. The second temperature control also means PID control started when the measured temperature Tp reaches the target temperature Ts. The second temperature control time is a time (length of time) when the second temperature control is performed.

In the first temperature control, the measured temperature Tp was within the range of plus or minus 5° C. of the target temperature Ts. Also in the second temperature control, the actually measured temperature Tp was within the range of plus or minus 5° C. of the target temperature Ts. Also in the temperature control of Comparative Example 2 and Comparative Example 4, the measured temperature Tp was within the range of plus or minus 5° C. of the target temperature Ts.

The silane coupling agent (“Si75” manufactured by Degussa Co., Ltd.) kneads at 130° C. (first temperature control), where the reaction with silica hardly progresses at 130° C. and the reaction with silica proceeds at 150° C. Then, the reaction rate of the silane coupling agent was improved by following the procedure of kneading at 150° C. (second temperature control) (see Comparative Example 1, Comparative Example 2 and Example 1). By this procedure, dispersibility, wet road braking performance, and fuel economy were also improved (see Comparative Example 1, Comparative Example 2 and Example 1).

The effect of improving the reaction rate by this procedure (the procedure of kneading at 130° C. and kneading at 150° C.) was greater in the combined system of silica 1 and silica 2 than in the case of silica 2 alone. Specifically, in the combined system, the effect of improving the reaction rate was 10% (see Comparative Example 2 and Example 1). On the other hand, in the single system, the effect of improving the reaction rate was 5% (see Comparative Example 3 and Comparative Example 4). The combined system was also more effective than the single system in improving the dispersibility, wet road surface braking property, and fuel economy (see Comparative Example 2 and Example 1; see Comparative Example 3 and Comparative Example 4).

Preparation of Unvulcanized Rubber in Comparative Example 5 According to Table 2, the compounding agent excluding sulfur and vulcanization accelerator and rubber were put into a B-type Banbury mixer, kneaded under PID control, and discharged at 160°C. , A rubber mixture was obtained. That is, the compounding agent and the rubber were kneaded at the target temperature Ts=150° C. and discharged at 160° C. to obtain a rubber mixture. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation of Unvulcanized Rubber in Example 5 According to Table 2, the compounding agent excluding sulfur and vulcanization accelerator and rubber were put into a B-type Banbury mixer, kneaded under PID control, and discharged at 160°C. , A rubber mixture was obtained. That is, the compounding agent and the rubber were kneaded at the target temperature Ts=130° C., then at the target temperature Ts=150° C., and discharged at 160° C. to obtain a rubber mixture. Next, the rubber mixture, sulfur and vulcanization accelerator were charged into a B type Banbury mixer to obtain an unvulcanized rubber.

Preparation and Evaluation of Vulcanized Rubber Unvulcanized rubber was vulcanized at 150° C. for 30 minutes to obtain a vulcanized rubber. Each item (reaction rate, dispersibility, wet road surface braking property, low fuel consumption) was evaluated by the above method, and the results are shown in Table 2. Regarding the dispersibility, the result of Example 5 is shown in Table 2 as an index with the Payne effect of Comparative Example 5 being 100. The larger the index, the better the dispersibility of the filler. With respect to the wet road surface braking property, the reciprocal of impact resilience in Comparative Example 5 is set to 100, and the reciprocal of Example 5 (reciprocal of impact resilience) is shown in Table 2. The larger the index, the better the wet road braking performance. Regarding fuel economy, the tan δ of Example 5 is shown in Table 2 as an index with tan δ of Comparative Example 5 as 100. The larger the index, the lower the tan δ and the better the fuel economy.

In each temperature control (first temperature control in Example 5, second temperature control in Example 5, temperature control in Comparative Example 5), the measured temperature Tp was within the range of plus or minus 5°C of the target temperature Ts. ..

The reaction rate of the silane coupling agent, dispersibility, wet road surface braking property, and low Fuel economy was improved (see Comparative Example 5 and Example 5).

The effect of improving the reaction rate by this procedure (the procedure of kneading at 130° C. and kneading at 150° C.) was 58% in fill factor, which was larger than 61% in fill factor. Specifically, with a fill factor of 58%, the effect of improving the reaction rate was 10% (see Comparative Example 2 and Example 1). On the other hand, when the fill factor was 61%, the effect of improving the reaction rate was 6% (see Comparative Example 5 and Example 5). The effect of improving the dispersibility, wet road surface braking property, and fuel economy was also higher in the fill factor of 58% than in the fill factor of 61% (see Comparative Example 2 and Example 1, see Comparative Examples 5 and 5).

Claims (4)

In order to suppress the reaction of silica and the silane coupling agent, at least rubber, a step of kneading the silica and the silane coupling agent while controlling the kneading temperature,
As the reaction proceeds, including a step of kneading while controlling the kneading temperature,
The silica includes a first silica having a specific surface area of more than 200 m ² /g according to a nitrogen adsorption method,
Method for producing rubber composition. The step of kneading so that the reaction is suppressed includes kneading so that the kneading temperature is kept constant,
The step of kneading so that the reaction proceeds includes kneading so that the kneading temperature is kept constant,
The method for producing the rubber composition according to claim 1. In the step of kneading so that the reaction is suppressed, kneading with a closed kneader,
The method for producing a rubber composition according to claim 1 or 2, wherein even in the step of kneading so that the reaction proceeds, kneading is performed by the closed kneader. A step of producing a rubber composition by the method for producing a rubber composition according to claim 1,
A step of producing an unvulcanized tire using the rubber composition,
Tire manufacturing method.

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