JP6981236B2 - Rubber kneading method - Google Patents

Description

The present invention relates to a rubber kneading method.

Conventionally, for example, as a rubber kneading method for kneading a rubber composition containing unvulcanized rubber and silica, a silane coupling agent may be added to uniformly disperse silica in the unvulcanized rubber. Are known. When such rubber in which silica is uniformly dispersed is molded as, for example, a tire, the tire is excellent in rolling resistance performance, durability performance and the like.

However, in this type of kneading method, the reaction of silica with the silane coupling agent produces, for example, a reaction product containing ethanol. This reaction product becomes a factor that inhibits the reaction between silica and the silane coupling agent. Therefore, for example, in Patent Document 1 below, it is proposed to air blow the inside of the casing in order to discharge the reaction product from the casing in which the rubber composition is kneaded.

Japanese Unexamined Patent Publication No. 2014-217985

However, it has been further required to uniformly disperse silica and knead it into unvulcanized rubber.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a rubber kneading method capable of further uniformly dispersing silica and kneading it into rubber.

The present invention is a rubber kneading method for kneading a rubber composition containing rubber, silica, and a silane coupling agent by a closed kneading device, the first step of kneading the rubber composition, and the first step. Includes a second step of supplying the rubber composition with a gas having a temperature lower than the temperature of the rubber composition in one step, and a third step of discharging the reaction product produced in the first step. , The second step is performed during the first step.

In the rubber kneading method according to the present invention, it is desirable that the temperature of the gas is 10 to 80 ° C.

In the rubber kneading method according to the present invention, it is desirable that the pressure of the gas is 0.1 to 1.2 MPa.

In the rubber kneading method according to the present invention, it is desirable that the gas is supplied to the rubber composition from a plurality of air supply passages.

In the rubber kneading method according to the present invention, the closed type kneading device has a pair of rotors, and the plurality of air supply passages are arranged on either one side of the pair of rollers. And a second air supply path arranged between the pair of rotors.

In the rubber kneading method according to the present invention, it is desirable that the closed kneading device has a kneading chamber in which the pair of rotors are housed, and the reaction product is discharged from above the kneading chamber. ..

The rubber kneading method of the present invention includes a step of discharging the reaction product produced by the kneading. Therefore, since the silica and the coupling agent can be effectively reacted, the silica can be uniformly dispersed and kneaded into the rubber. Further, in the rubber kneading method of the present invention, during the first step of kneading the rubber composition, a second step of supplying a gas having a temperature lower than the temperature of the rubber composition in the first step to the rubber composition is performed. conduct. As a result, the temperature of the rubber composition in the first step is lowered, so that the number of shears associated with the kneading of the rubber composition by the kneading device can be increased. Therefore, the silica can be more uniformly dispersed and kneaded into the rubber.

It is a schematic diagram which shows one Embodiment of the closed type kneading apparatus used in the rubber kneading method of this invention. It is the schematic of the chamber of the closed type kneading apparatus of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a closed-type kneading device (hereinafter, may be simply referred to as “device”) 1 used in the rubber kneading method of the present embodiment. As shown in FIG. 1, the apparatus 1 of the present embodiment can knead a rubber composition (not shown) containing rubber (unvulcanized rubber), silica, and a silane coupling agent. The rubber composition kneaded in the device 1 of the present embodiment is suitably adopted as, for example, a rubber member of a tire mounted on a vehicle.

As the rubber of this embodiment, it is preferable to use a diene-based rubber. As the diene-based rubber, natural rubber (NR) or diene-based synthetic rubber can be used. Examples of the diene synthetic rubber include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). When rubber is used as a tire, for example, NR, BR, and SBR are preferable because it improves fuel efficiency and wet grip performance in a well-balanced manner. These rubber components may be used alone or in combination of two or more.

The silica of the present embodiment is not particularly limited, but silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), and the like are preferable. In particular, silica prepared by a wet method is preferable because it has many silanol groups on the surface and many reaction points with the silane coupling agent.

Silica, the nitrogen adsorption specific surface area (N2SA) is 90m ² / g or more, preferably 95 m ² / g or more, more preferably 100 m ² / g or more. When the rubber composition is used as a tire, if the N2SA of silica ^{is less than 90 m 2} / g, the reinforcing property of the rubber required for the tire cannot be ensured, and the fracture strength and wear resistance may not be ensured. Further, N2SA of silica is preferably 300 meters ² / g or less, more preferably 24m ² / g. If the N2SA of silica ^{exceeds 300 m 2} / g, workability may deteriorate and processing may become difficult. The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The silica content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If the silica content is less than 5 parts by mass, the above-mentioned reinforcing property cannot be obtained. The silica content is preferably 200 parts by mass or less, more preferably 180 parts by mass or less. If the silica content exceeds 200 parts by mass, the processability may deteriorate. The silica is not particularly limited, but for example, Ultrasil VN3 manufactured by Evonik Industries, Inc. is desirable.

In the present invention, silica (1) and silica (2) satisfying the following conditions may be used in combination as silica. By using silica (1) and silica (2) in combination, it is possible to achieve both reduction of rolling resistance as tire performance and improvement of fracture strength, and further remarkably improve workability.

Silica (1) is N2SA of preferably 125m ² / g or less, more preferably 100 m ² / g or less, more preferably 80 m ² / g or less, particularly preferably not more than 60 m ² / g. If it exceeds 125 m ² / g, the effect of blending with silica (2) is small. The N2SA of silica (1) is preferably 20 m ² / g or more, more preferably 30 m ² / g or more. If it is less than 20 m ² / g, the hardness and breaking strength of the rubber of the obtained rubber composition tend to decrease.

The silica (1) is not particularly limited, and for example, Ultrazil 360 manufactured by Degussa, Z40 manufactured by Rhodia, RP80 manufactured by Rhodia, and the like are desirable.

As the silica (1), only one type may be used, or two or more types may be used in combination.

The content of silica (1) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 parts by mass, the rolling resistance tends not to be sufficiently reduced. The content of silica (1) is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and further preferably 50 parts by mass or less. If it exceeds 70 parts by mass, the rolling resistance can be reduced, but the workability, the hardness of the rubber and the breaking strength tend to decrease.

The N2SA of silica (2) is preferably 155 m ² / g or more, more preferably 170 m ² / g or more, ^{still more preferably 180 m 2} / g or more, and particularly preferably 190 m ² / g or more. If it is less than 155 m ² / g, it may not be sufficient to achieve both reduction of rolling resistance and improvement of wet grip performance by blending with silica (1). The N2SA of silica (2) is preferably 400 m ² / g or less, more preferably 360 m ² / g or less, ^{still more preferably 300 m 2} / g or less, particularly preferably 240 m ² / g or less, and most preferably 210 m ² /. It is less than or equal to g. If it exceeds 400 m ² / g, not only the workability is deteriorated, but also the rolling resistance tends not to be sufficiently reduced.

The silica (2) is not particularly limited, and for example, Zeosyl 1205MP manufactured by Rhodia and Ultrazil VN3-G manufactured by Degussa are desirable.

As the silica (2), only one type may be used, or two or more types may be used in combination.

The content of silica (2) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 parts by mass, sufficient fracture strength tends not to be obtained. The content of silica (2) is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and further preferably 55 parts by mass or less. If it exceeds 70 parts by mass, the workability tends to deteriorate even if the breaking strength is improved.

The total content of silica (1) and silica (2) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and particularly preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. It is 30 parts by mass or more, most preferably 45 parts by mass or more. If it is less than 10 parts by mass, a sufficient reinforcing effect by blending silica (1) and silica (2) may not be obtained. The total content of silica (1) and silica (2) is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less. If it exceeds 150 parts by mass, it becomes difficult to uniformly disperse silica in the rubber composition, which may not only deteriorate the processability of the rubber composition but also increase the rolling resistance.

As the silane coupling agent of the present embodiment, bis (3-triethoxysilylpropyl) tetrasulfide and 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide are preferably adopted. Such a silane coupling agent is excellent in terms of ease of temperature control of the reaction with silica and an effect of improving the reinforcing property of the rubber composition. These silane coupling agents may be used alone or in combination of two or more.

The content of the silane coupling agent is preferably 1 part by mass or more, and more preferably 2 parts by mass or more with respect to 100 parts by mass of silica. When the content of the silane coupling agent is less than 1 part by mass, the viscosity of the unvulcanized rubber composition tends to be high and the processability tends to be poor. The content of the silane coupling agent is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less with respect to 100 parts by mass of silica. If the content of the silane coupling agent exceeds 20 parts by mass, the compounding effect of the silane coupling agent cannot be obtained as much as the content, and the cost tends to be high.

In the present embodiment, the rubber composition contains an antiaging agent, a softener, a vulcanizing agent, a vulcanization accelerator, and a vulcanization aid.

The anti-aging agent of the present embodiment is appropriately selected from amine-based, phenol-based, and imidazole-based compounds, carbamic acid metal salts, waxes, and the like.

As the softener of the present embodiment, petroleum-based softeners, fatty oil-based softeners, fatty acids and the like are used. Examples of the petroleum-based softener include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum and the like. Examples of the fatty oil-based softener include soybean oil, palm oil, castor oil, linseed oil, rapeseed oil, and coconut oil. Examples of waxes include tall oil, sub, beeswax, carnauba wax, lanolin and the like. Examples of fatty acids include linoleic acid, palmitic acid, stearic acid, and lauric acid. The blending amount of the softener is preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component. Such a softener can suppress a decrease in wet grip performance.

As the vulcanizing agent of the present embodiment, an organic peroxide or a sulfur-based vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, and the like. 5-Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexin- 3 or 1,3-bis (t-butylperoxypropyl) benzene or the like can be used. As the sulfur-based vulcanizing agent, for example, sulfur, morpholine disulfide, or the like can be used. Of these, sulfur is preferred.

The vulcanization accelerator of the present embodiment is, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based, aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization. Accelerators and the like are adopted. These may be used alone or in combination of two or more.

As the vulcanization aid of this embodiment, stearic acid, zinc oxide (zinc white) and the like are used.

In addition, the rubber composition of the present embodiment contains various compounding agents and additives such as other reinforcing agents, various oils, plasticizers, coupling agents and the like for tires or general rubber compositions. Can be done. Further, it is desirable that the contents of these compounding agents and additives are also general amounts.

The apparatus 1 of the present embodiment includes a kneader main body 2 capable of kneading the rubber composition, an air supply means 3 for supplying gas to the rubber composition, and a reaction product produced from the rubber composition (not shown). ) Is provided with a discharging means 4 for discharging) to the outside of the kneader main body 2. In this embodiment, silica and a silane coupling agent are kneaded to produce a reaction product containing water and ethanol.

As the kneading machine main body 2 of the present embodiment, a small vanbury mixer having a kneading capacity of 300 liters or less is adopted. The kneader main body 2 includes, for example, a chamber 6 having a kneading chamber 6a in which a pair of rotatable rotors 5 and 5 are housed, and a ram weight 7 for pressurizing the rubber composition charged into the kneading chamber 6a. I'm out. The ram weight 7 improves the stirring efficiency and kneading efficiency of the rotor 5. The kneader main body 2 is not limited to such a Banbury mixer.

The chamber 6 of the present embodiment is provided with an opening 8 in which the rubber composition can be charged in the upper part of the rotor 5 and an discharge port 9 in which the rubber composition kneaded in the lower part of the rotor 5 can be discharged. .. The kneading chamber 6a has, for example, a substantially gourd-shaped cross-sectional shape in which two circumferential surfaces concentric with the pair of rotors 5 and 5 are connected. The opening 8 and the discharge port 9 are provided, for example, in the constricted portion having a gourd-like cross section.

The rotor 5 is provided with stirring blades spirally around a base shaft rotatably supported, for example, in the same direction or in opposite directions to each other via a rotating means (not shown) having a well-known structure such as a motor. It is driven to rotate.

The opening 8 is located, for example, at the lower end of the vertical hole 11 leading to the input port 10. The charging port 10 is formed of, for example, a well-known opening / closing structure that can be opened to the outside, and the rubber composition is charged into the kneader main body 2. The discharge port 9 has, for example, an openable structure, and the kneaded rubber composition (hereinafter, may be simply referred to as “kneaded rubber”) is discharged in a lump form.

In the present embodiment, the ram weight 7 is arranged in the vertical hole 11, and closes the opening 8 of the chamber 6 at the lower limit position. The ram weight 7 is supported so as to be able to move up and down by a well-known drive means 12 such as a cylinder. The ram weight 7 can be urged downward by the driving means 12 and lowered to pressurize the rubber composition charged into the kneading chamber 6a. The driving means 12 of the present embodiment has a sensor (not shown) and detects the upper limit position and the lower limit position of the ram weight 7.

The air supply means 3 includes, for example, a well-known blower for blowing gas, a well-known temperature controller (not shown) for controlling the temperature of the gas blown from the blower, and a temperature controller. It includes a supply air passage 16 for supplying a temperature-controlled gas into the kneading chamber 6a.

The gas is preferably air or nitrogen, for example. As the blower of the present embodiment, for example, an air compressor, a blower, or the like that can compress air is preferably adopted.

As the temperature controller, for example, a heat pump type cooling unit having a well-known structure capable of cooling a gas or the like is preferably adopted.

The temperature of the gas supplied to the rubber composition is set lower than the temperature of the rubber composition kneaded in the kneading chamber 6a. As a result, the temperature of the rubber composition during kneading to which the gas is supplied is lowered, so that the number of shears to the rubber composition by the rotor 5 (rotor rotation speed) can be increased. Therefore, silica can be uniformly dispersed and kneaded into the rubber.

The temperature of the gas supplied to the rubber composition is preferably 10 to 80 ° C. in order to effectively exert the above-mentioned action. In order to further increase the number of shears to the rubber composition by the rotor 5, the temperature of the gas is preferably 50 ° C. or lower, and more preferably 20 ° C. or lower. When the temperature of the gas is less than 10 ° C., the temperature of the rubber composition during kneading becomes too low and the viscosity of the rubber composition deteriorates, so that silica may not be uniformly dispersed.

The pressure of the supplied gas is preferably 0.1 to 1.2 MPa. As a result, the inside of the kneading chamber 6a is made positive pressure, and the reaction product can be discharged from the inside of the kneading chamber 6a. If the pressure of the gas exceeds 1.2 MPa, the ram weight 7 will rise during kneading, and kneading may not be possible. Further, when the pressure of the gas is less than 0.1 MPa, the effect of discharging the above-mentioned reaction product may be reduced.

FIG. 2 is an enlarged schematic view of the chamber 6 of the present embodiment. As shown in FIG. 2, in the present embodiment, the supply air passage 16 is located between the first air supply passage 16A arranged on any one side of the pair of rotors 5 and 5 and the pair of rotors 5 and 5. It includes the second air supply passage 16B to be arranged. It is desirable that the air supply passage 16 is provided with, for example, a well-known on-off valve (not shown). This makes it possible to control the amount of gas supplied and the timing of supply.

In the present embodiment, the first air supply passage 16A is arranged so as to supply toward the outer peripheral surface of the rotor 5. Such a first air supply passage 16A can directly supply a gas to the rubber composition attached to the rotor 5. Thereby, the reaction product produced by the rubber composition can be removed from the rubber composition. In this embodiment, two first air supply passages 16A are formed on each rotor 5 and 5 side.

In the present embodiment, the second air supply passage 16B is arranged so as to supply between the pair of rotors 5 and 5. Such a second air supply passage 16B can directly supply a gas to the rubber composition arranged between the pair of rotors 5 and 5 to which a large shearing force is applied. In this embodiment, one second air supply passage 16B is formed.

As shown in FIG. 1, the discharge means 4 includes, for example, a vacuum device (not shown) made of a vacuum pump or the like having a well-known structure, a discharge hood 18 provided on the upper part of an inlet 10, a vacuum device, and a discharge hood 18. Includes a discharge duct 19 that succeeds. In the case of the present embodiment, the reaction product in the kneading chamber 6a is discharged from the vertical hole 11 together with the gas through the gap between the ram weight 7 and the chamber 6 to the vacuum device via the discharge hood 18. In this way, the reaction product is discharged above the kneading chamber 6a. Therefore, the discharge of the rubber composition having a higher specific density than the reaction product is suppressed.

The discharging means 4 is not limited to such an embodiment. For example, the discharge means 4 may be formed to further include a discharge pipe (not shown) that connects the kneading chamber 6a and the vertical hole 11 and extends vertically. As a result, the above-mentioned action is effectively exerted. In this case, the reaction product in the kneading chamber 6a is discharged from the discharge pipe to the vacuum device via the vertical hole 11. The discharge pipe has, for example, a structure that penetrates the ram weight 7 or the chamber 6. It is desirable that the discharge pipe is provided with, for example, a well-known on-off valve (not shown). As a result, the timing of discharge of the reaction product can be controlled.

Next, a rubber kneading method for kneading the rubber composition will be described using the above-mentioned device 1. The rubber kneading method of the present embodiment includes a first step of kneading the rubber composition, a second step of supplying a gas having a temperature lower than the temperature of the rubber composition in the first step to the rubber composition, and a first step. It includes a third step of discharging the reaction product produced in one step.

In the first step, the ram weight 7 is positioned at the upper limit position, and for example, rubber, silica, a silane coupling agent, and the like conveyed from the conveying means 20 such as a conveyor are respectively from the input port 10 to the vertical hole 11 and the vertical hole 11. It is charged into the kneading chamber 6a through the opening 8. In the first step, in order to suppress vulcanization of the rubber composition, a rubber composition excluding a vulcanizing agent, a vulcanization accelerator and the like is added.

Next, in the first step, for example, the ram weight 7 is lowered and the pair of rotors 5 and 5 are rotated to knead the rubber composition in the kneading chamber 6a. The first step of the present embodiment includes an initial kneading step until the ram weight 7 reaches the lower limit position, and a main kneading step after the ram weight 7 reaches the lower limit position.

In the initial kneading step, the ram weight 7 of the kneader main body 2 is urged downward by the driving means 12 to descend the vertical hole 11. The ram weight 7 is in contact with the rubber composition, for example, before reaching the lower limit position, and pressurizes the rubber composition. At this time, the rubber composition is kneaded by the rotor 5.

In the initial kneading step of the present embodiment, it is desirable that the ram weight 7 is lowered for a certain period of time by the first urging force. It is desirable that the first urging force is smaller than the maximum urging force that urges the ram weight 7 in the main kneading process. The first urging force is preferably 50% or less of the maximum urging force.

Such an initial kneading step improves the fluidity of the rubber composition in the kneading chamber 6a at the initial stage of kneading, and is a rubber composition containing silica other than rubber or a silane coupling agent (hereinafter, simply referred to as "additive"). In some cases) can be prevented from being locally placed on the rubber. In addition, since the initial kneading step improves the uptake of the additive into the rubber, the blowout of the additive can be suppressed. Therefore, a high-quality kneaded rubber having excellent dispersion of additives is stably formed.

In the main kneading step, the ram weight 7 is located at the lower limit position and closes the opening 8 of the kneading chamber 6a. The ram weight 7 is urged downward by the driving means 12 to pressurize the rubber composition in the kneading chamber 6a. At this time, the rubber composition is kneaded by the rotor 5.

In the main kneading step, it is desirable that the ram weight 7 is urged downward with the maximum urging force at the lower limit position. As a result, the rubber composition is kneaded in a state of being greatly pressurized. Therefore, the time required for the main kneading process is shortened.

In the main kneading step, the temperature of the rubber composition is set to, for example, 110 to 180 ° C. The kneading time in the main kneading step is, for example, about 1 to 15 minutes.

It is desirable that the main kneading step further includes an ascending step of opening the opening 8 of the chamber 6 by increasing the ram weight 7. In the ascending step, for example, the ram weight 7 is raised to the upper limit position and then lowered to the lower limit position again. It is desirable that the ascending step is performed at least at the beginning of the main kneading step. In such an ascending step, the rebound resilience of the rubber composition is restored, and the rubber composition is pressurized again, so that the kneading efficiency can be improved.

In the second step, in the present embodiment, the air compressed by the air compressor is cooled by the temperature controller and supplied into the kneading chamber 6a via the air supply passage 16. As a result, the temperature of the rubber composition is lowered, so that the rotor 5 can be further rotated so as to raise the rubber composition to the upper limit of the temperature. Therefore, since a large shearing force can be applied to the rubber composition, silica can be more uniformly dispersed and kneaded into the rubber.

Such a second step is performed during the first step. It is desirable that the second step is performed while monitoring the physical properties of the rubber composition by, for example, a control means (not shown).

In the third step, in the present embodiment, the vacuum device is driven to discharge the reaction product generated in the kneading chamber 6a from the discharge duct 19 through the gap between the ram weight 7 and the chamber 6 via the discharge hood 18. Forced to discharge.

In this embodiment, such a third step is performed during the first step. It is desirable that the third step be performed at the same time as the second step by, for example, a control means (not shown) described above.

In the present embodiment, after the first step, a fourth step of adding a rubber composition for promoting vulcanization and kneading the rubber composition is performed. In the fourth step, for example, the ram weight 7 is raised by the driving means 12, and the vulcanizing agent, the vulcanization accelerator, and the vulcanization aid are conveyed by the conveying means 20 and charged from the charging port 10. Next, the ram weight 7 is lowered, kneaded by the rotor 5 and vulcanized.

In the fourth step, for example, the second step and the third step are not performed in order to promote the vulcanization of the rubber composition.

Finally, for example, the discharge port 9 is opened and the kneaded rubber is discharged in a lump form. The kneaded rubber discharged from the discharge port 9 is conveyed to, for example, an extruder and molded into a rubber strip or the like.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

The rubber composition shown in Table 1 was put into the closed kneading device shown in FIG. 1, and a kneaded rubber was prototyped. The kneaded rubber was then tested for Mooney viscosity and silica dispersibility. Except for the specifications listed in Table 2, prototypes are made with common specifications. Each test method is as follows.

<Moony viscosity>
According to JIS K6300, Mooney viscosity MLs at 10 points of the kneaded rubber at 110 ° C. were measured, and their coefficient of variation (standard deviation / average value) was obtained. The coefficient of variation of Mooney viscosity was measured after the first step and the fourth step, respectively. The upper limit of the temperature of the rubber composition during kneading in the first step is set to 130 ° C. The result is displayed as an index with the coefficient of variation of Comparative Example 1 after each step as 100. The smaller the value, the smaller the variation in Mooney viscosity ML, indicating that the silica is uniformly dispersed.

<Silica dispersibility>
Using the RPA2000 type testing machine manufactured by Alpha Technologies, the strain shear force G * from 1% to 64% of the strain of the kneaded rubber after vulcanization was measured with the following specifications, and the maximum value of G * was measured. The silica pain effect ΔG * was obtained from the difference in the minimum values of G *. The result is displayed as an exponent with the pane effect ΔG * of Comparative Example 1 as 100. It is judged that the smaller the value, the better the silica dispersibility, the better the reactivity between the silica and the silane coupling agent, and the uniformly dispersed silica.
Frequency: 10Hz
Amplitude angle: 1 °
Kneaded rubber temperature: 100 ° C
The test results are shown in Table 2.

As is clear from Table 2, the kneaded rubber of the example has less variation in Mooney viscosity than the comparative example and has excellent silica dispersibility, so that it is understood that silica is uniformly dispersed. Will be done.

1 Sealed kneading device

Claims (6)

A rubber kneading method for kneading a rubber composition containing rubber, silica, and a silane coupling agent by a closed kneading device.
The first step of kneading the rubber composition and
In the second step of supplying the rubber composition with a gas having a temperature lower than the temperature of the rubber composition in the first step,
Including a third step of discharging the reaction product produced during the first step.
The second step is performed during the first step ,
The second step includes a step of cooling the gas with a temperature controller.
Rubber kneading method. The rubber kneading method according to claim 1, wherein the temperature of the gas is 10 to 80 ° C. The rubber kneading method according to claim 1 or 2, wherein the pressure of the gas is 0.1 to 1.2 MPa. The rubber kneading method according to any one of claims 1 to 3, wherein the gas is supplied to the rubber composition from a plurality of air supply passages. The closed kneading device has a pair of rotors and has a pair of rotors.
Wherein the plurality of air supply passage includes a first air supply passage that is disposed either side of the pair of row data, and a second air supply passage disposed between the pair of rotors, claims 4. The rubber kneading method according to 4. The closed kneading device has a kneading chamber in which the pair of rotors are housed.
The rubber kneading method according to claim 5, wherein the reaction product is discharged from above the kneading chamber.

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