JP5567302B2 - Silica-containing rubber kneading system and kneading method - Google Patents

Description

The present invention relates to a kneading system and a kneading method for silica-blended rubber.

Conventionally used rubber kneading equipment (rubber kneading system) for tires is kneaded with a closed rubber kneader such as a large or small Banbury mixer, then via a feed screw as necessary, and then an open roll. In general, equipment for processing into a sheet and cooling is used. Here, normally, in a closed rubber kneader, a rubber material, which is a raw material, and additives such as carbon, silica, and a silane coupling agent are charged into the kneading chamber through the raw material charging portion, and then the kneading chamber is added by a floating weight. Pressed and kneaded by a rotor rotating in the kneading chamber.

In recent tread rubber blends, blends formulated with silica and silane coupling agents have become mainstream in order to meet the needs of wet grip performance and rolling resistance (low fuel consumption). In general, it is known that when the reaction between silica and a silane coupling agent is sufficiently advanced, the physical properties of rubber are improved and the wear resistance is improved. Here, in order to react these efficiently, it is considered desirable to knead for a long time at a specific temperature.

However, the Banbury mixer has a strong rubber shearing force and the kneaded rubber temperature rises during the kneading process, so it is difficult to adjust the temperature. Therefore, it is difficult to knead for a certain time at a specific temperature. Also, when a silane coupling agent is added to a Banbury mixer together with a rubber material or silica and kneaded, adhesion between the rotor and rubber is likely to occur due to the reaction between the silane coupling agent and the Banbury rotor. Will get worse.

Many improved closed rubber kneaders have been proposed in Patent Document 1 and the like, but even if such a closed rubber kneader is used, it is difficult to adjust the temperature. There is still room for improvement in improving the reaction rate and thereby improving the physical properties of rubber. There is also a need for improved workability such as adhesion between the rotor and rubber.

JP 2003-170421 A

The present invention solves the above-mentioned problems and enables silica to obtain a vulcanized rubber composition having excellent rubber physical properties by enabling high-efficiency coupling treatment of raw rubber and silica with a silane coupling agent in the kneading step. An object is to provide a kneading system and a kneading method for compounded rubber.

The present invention relates to a closed first rubber kneading machine for kneading raw material rubber and silica, and temperature control of a kneading object kneading the primary kneaded rubber discharged from the first rubber kneading machine and a silane coupling agent. And a second rubber kneading machine capable of carrying out the above process.
In the kneading system, the first rubber kneading machine is a Banbury mixer, the second rubber kneading machine is a continuous kneading machine, and the continuous kneading machine is kneaded with a feed area in order from the primary kneading rubber charging side. It is preferable that an area is provided, the silane coupling agent is supplied in the feed area, and at least the temperature of the kneading object in the kneading area can be adjusted. Here, the continuous kneader is preferably a biaxial continuous kneader.
In the kneading system, the second rubber kneader is preferably capable of adjusting the temperature of the kneading object to 120 to 200 ° C.

The present invention also includes a step (I) of kneading raw rubber and silica using a sealed first rubber kneader to obtain a primary kneaded rubber, and the temperature of the object to be kneaded is different from that of the first rubber kneader. And kneading the primary kneaded rubber and the silane coupling agent using an adjustable second rubber kneader to obtain a secondary kneaded rubber (II). About.
In the kneading method, the first rubber kneader is a Banbury mixer, the second rubber kneader is capable of supplying the silane coupling agent in order from the primary kneading rubber charging side, and the primary kneading. A continuous kneading machine provided with a kneading area capable of kneading rubber and the silane coupling agent, wherein after the step (II) supplies the silane coupling agent in the feed area, the second rubber It is preferable to knead the mixture of the primary kneading rubber as the kneading object and the silane coupling agent at 120 to 200 ° C. in at least the kneading area of the kneading machine.

According to the present invention, a sealed first rubber kneader for kneading raw material rubber and silica, and a kneading target for kneading the primary kneaded rubber and the silane coupling agent discharged from the first rubber kneader. A silica compounded rubber kneading system equipped with a second rubber kneader capable of adjusting the temperature, and a kneading method using the system, so that the rubber can be heated and sheared efficiently, and the raw rubber and silica are coupled with silane coupling. Coupling can be performed with high efficiency by the agent. Accordingly, excellent rubber properties (hardness, tensile strength, breaking strength, rolling resistance, wet grip performance, dry grip performance, etc.) can be obtained in the rubber composition after vulcanization.

Schematic diagram of kneading system (kneading equipment) and kneading method for silica-blended rubber of the present invention Schematic diagram of sealed rubber kneader Enlarged plan view of screw of twin screw extruder Cross-sectional illustration of kneading area

A rubber kneading system for silica-containing rubber according to the present invention comprises a sealed first rubber kneading machine for kneading raw material rubber and silica, and a primary kneading rubber and a silane coupling agent discharged from the first rubber kneading machine. A second rubber kneader capable of adjusting the temperature of the kneaded object to be kneaded. Further, the method for kneading the silica-blended rubber of the present invention includes the step (I) of obtaining a primary kneaded rubber by kneading raw material rubber and silica using a hermetic first rubber kneader, and the first rubber kneader, And the step (II) of obtaining the secondary kneaded rubber by kneading the primary kneaded rubber and the silane coupling agent using a second rubber kneader capable of adjusting the temperature of the object to be kneaded. That is, in the present invention, a second rubber kneader capable of adjusting the temperature is laid out downstream of the hermetic first rubber kneader, and a silane coupling agent is injected into the second rubber kneader. Kneading with the primary kneading rubber produced by the rubber kneader. For this reason, the rubber kneaded and heated by the first rubber kneader can be kneaded for a certain period of time while accurately adjusting the temperature to the predetermined temperature with the second rubber kneader. Therefore, since the reaction between silica and the silane coupling agent can be controlled by controlling the kneading temperature and kneading time, the coupling treatment between the silica and the raw rubber can be sufficiently advanced, and the rubber physical properties can be improved.

Moreover, since it is not necessary to introduce a silane coupling agent into the closed first rubber kneader, rubber adhesion (deterioration in workability and safety) in the first rubber kneader can be improved. Further, since the kneaded rubber kneaded by the first rubber kneader can be kneaded by the second rubber kneader capable of adjusting the temperature without cooling, high productivity can be secured. Furthermore, by adjusting the size (length, etc.) of the second rubber kneader, production can be performed while maintaining the production efficiency of the hermetic first rubber kneader.

Hereinafter, the kneading system and the kneading method of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a schematic view of a kneading equipment (kneading system) used in the present invention.
In the system of the present invention, first, a sealed first rubber kneader is provided, and the raw rubber and silica are kneaded using the first rubber kneader to obtain a primary kneaded rubber (step (I)).

In the system of FIG. 1, the hermetic first rubber kneader 1 includes a Banbury mixer 11 as shown in FIG. 2 (for example, a large Banbury mixer with a kneading capacity of 200 to 400 liters, a small banbury mixer of 200 liters or less). Banbury mixer) can be used. The Banbury mixer 11 includes a mixing chamber 13 provided with a pair of agitating rotors 12 and 12 arranged in parallel, kneading raw material rubber, silica and the like put into the mixing chamber 13, and as the primary kneading rubber, the mixing chamber 13. It discharges in the lump form from the openable discharge port 14 provided in (step (I): first base kneading step). In this example, the closed first rubber kneader 1 kneads a material containing a reinforcing agent such as the raw rubber and silica and not containing a silane coupling agent, a vulcanizing agent and a vulcanization accelerator. Illustrated. Examples of the reinforcing agent include carbon black in addition to silica.

The stirring rotor 12 has a well-known configuration in which, for example, a spiral blade is provided around a base shaft that is rotatably supported, and is disposed in a mixing chamber 13 provided in the kneader body 15. Each agitating rotor 12 is rotationally driven in the same direction or in the opposite direction via drive means (not shown) including a motor attached to the kneader main body 15. The mixing chamber 13 has a cross-sectional gourd shape in which two circumferential surfaces concentric with the pair of stirring rotors 12 and 12 are connected. The lower end of the vertical hole 17 leading to is connected. The vertical hole 17 is provided with a floating weight 18 supported by a cylinder or the like so as to be movable up and down. The floating weight 18 pressurizes the raw rubber, silica and the like charged into the mixing chamber 13 to improve the stirring efficiency and kneading efficiency by the stirring rotor 12.

The kneading machine main body 15 is provided with a drop door 19 for opening and closing the discharge port 14 formed in the lower part of the mixing chamber 13, and opening the kneaded primary kneaded rubber from the discharge port 14. Eject and drop in bulk.

In the first base kneading step in the first kneader, it is preferable that the temperature of the kneading material (kneading object) such as raw rubber and silica is adjusted to 120 to 200 ° C. The kneading time is preferably 1.5 to 10 minutes. If it is less than the lower limit, there is a tendency that filler dispersion becomes worse due to insufficient kneading and physical properties are lowered. When the upper limit is exceeded, productivity tends to deteriorate.

In the first base kneading step, the rotor rotation speed of the first rubber kneader 1 (Banbury mixer 11) is preferably 15 to 65 rpm. If it is less than 15 rpm, productivity tends to be poor (kneading time becomes too long). If it exceeds 65 rpm, the kneading time is short and filler dispersion tends to deteriorate, leading to a decrease in physical properties.

Examples of the raw rubber used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), and styrene butadiene rubber (SBR). Especially, it is preferable to use SBR and BR modified for silica from the viewpoint that the raw rubber and silica can be coupled with a silane coupling agent with high efficiency in the second rubber kneader.

Examples of the modified SBR include those modified with an organosilicon compound containing an alkoxy group described in JP-A-2001-114938.

When the modified SBR is used as the raw rubber, the blending amount of the modified SBR in 100% by mass of the raw rubber is preferably 20% by mass or more, more preferably 30% by mass or more. If it is less than 20% by mass, the silica dispersibility improving effect due to the modification effect tends to be small. The amount of the modified SBR is preferably 90% by mass or less, more preferably 80% by mass or less. If it exceeds 90 mass%, it may be difficult to handle as tire rubber.

The BR is not particularly limited. For example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having a high cis content such as BR150B, VCR412 manufactured by Ube Industries, Ltd. BR containing syndiotactic polybutadiene crystals can be used.

When BR is used as the raw rubber, the blending amount of BR in 100% by mass of the raw rubber is preferably 5% by mass or more, more preferably 10% by mass or more. Moreover, the blending amount of the BR is preferably 80% by mass or less, more preferably 70% by mass or less. If it is less than 5% by mass or more than 80% by mass, it may be difficult to handle as rubber for tires.

Silica is blended in the kneading step (step (I)) in the first rubber kneader. Examples of the silica include silica prepared by a dry method (anhydrous silicic acid) and silica prepared by a wet method. (Hydrous silicic acid) can be used. Since there are many silanol groups on the surface and there are many reaction points with a silane coupling agent, it is preferable to use silica prepared by a wet method.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica compounded in the step (I) is preferably 50 m ² / g or more, more preferably 80 m ² / g or more. If it is less than 50 m ² / g, the reinforcing property of silica is low, and there is concern about durability. The N ₂ SA of silica is preferably 250 m ² / g or less, more preferably 220 m ² / g or less. If it exceeds 250 m ² / g, kneading may be difficult.
The nitrogen adsorption specific surface area (N ₂ SA) of silica is a value measured by the BET method according to ASTM D3037-81.

The compounding quantity of the silica in process (I) becomes like this. Preferably it is 5 mass parts or more with respect to 100 mass parts of raw rubber, More preferably, it is 40 mass parts or more. If the amount is less than 5 parts by mass, the balance between fuel efficiency and wet grip performance tends to deteriorate. Moreover, the compounding quantity of this silica becomes like this. Preferably it is 150 mass parts or less, More preferably, it is 120 mass parts or less. If it exceeds 150 parts by mass, processing may be difficult.

In the kneading process in the first rubber kneader, in addition to the above materials, compounding agents conventionally used in the rubber industry, for example, inorganic and organic fillers such as carbon black, softeners such as oil, stearic acid, zinc oxide Various anti-aging agents, ozone degradation inhibitors, waxes and the like can be appropriately blended as necessary.

In the system of FIG. 1, a feed screw 2 is provided. Here, the primary kneaded rubber discharged from the first rubber kneader 1 is transferred by a feed screw 2 rotated by a driving means (not shown) such as a motor and supplied to the second rubber kneader 3.

Next, in the system of the present invention, a second rubber kneader capable of adjusting the temperature of the object to be kneaded is provided, and using the second rubber kneader, the temperature of the supplied primary kneaded rubber and the silane coupling agent is increased. By kneading while adjusting, a secondary kneaded rubber can be obtained (step (II)).

The second rubber kneader can be used without particular limitation as long as the temperature of the kneaded object (mixture of the first kneaded rubber and the silane coupling agent) can be adjusted. For example, a uniaxial extruder , A twin screw extruder, a twin screw kneader and the like. In particular, a feed area capable of supplying a silane coupling agent in order from the primary kneading rubber charging side and a kneading area capable of kneading the primary kneading rubber and the silane coupling agent are provided, and an object to be kneaded in the kneading area. A continuous kneader (such as a biaxial continuous kneader) whose temperature can be adjusted can be suitably used.

FIG. 1 shows an extruder (kneading extruder) having a feed area 3a, a kneading area 3b, and a cooling area 3c as an example of the second rubber kneading machine 3, and the feed area 3a of the kneading extruder. A silane coupling agent injection device 4 for injecting the silane coupling agent is provided.

In the system of FIG. 1, the primary kneaded rubber is transferred to the second rubber kneader 3 by the feed screw 2 and at the same time, the silane coupling agent is injected from the silane coupling agent injection device 4 into the feed area 3 a. The feed area 3a is not particularly limited as long as the primary kneaded rubber and the silane coupling agent can be introduced. The injecting device 4 is not particularly limited as long as it can inject a silane coupling agent. For example, a syringe type injecting device can be used.

As the silane coupling agent that can be used in the present invention, any silane coupling agent conventionally used in combination with silica can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-tri Ethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilyl) Butyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) Trisulfide Bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4- Triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N -Dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimeth Sisilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxy Sulfide series such as silylpropyl methacrylate monosulfide, mercapto series such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyltriethoxysilane , Vinyl type such as vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2- Amino-ethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane and other amino compounds, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycine Glycidoxy series such as sidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, nitro series such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, Examples include chloro-based compounds such as 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. Of these, Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) and Si266 (bis (3-triethoxysilylpropyl) disulfide) are preferable from the viewpoint of coupling treatment efficiency in a twin-screw kneader and workability.

The compounding amount of the silane coupling agent is preferably 2 parts by mass or more, more preferably 4 parts by mass or more with respect to 100 parts by mass of silica in the first kneaded rubber. If the amount is less than 2 parts by mass, the effect of improving physical properties due to the coupling effect of silica and polymer tends to be small. Moreover, the compounding quantity of this silane coupling agent becomes like this. Preferably it is 15 mass parts or less, More preferably, it is 12 mass parts or less. If it exceeds 15 parts by mass, the excess coupling agent may remain without reacting.

In the kneading area 3b of FIG. 1, the primary kneaded rubber supplied by the feed screw 2 and the silane coupling agent supplied from the silane coupling agent injection device 4 are further kneaded. FIG. 3 shows an enlarged plan view of a screw in a twin screw extruder as an example of the second rubber kneader 3. In the kneading area 3b of FIG. 1, for example, two screws as shown in FIG. The screws 31 and 32 are kneaded by a twin screw extruder arranged in parallel. The extruder is provided with a screw driving device (not shown).

FIG. 4 shows an example of a cross-sectional explanatory view of the kneading area 3b. In FIG. 4, the inside of the cylinder 41 in the kneading area 3 b has an oval shape, and the two screws 31 and 32 are arranged in a common cylinder hole. The rotation direction of the two screws 31 and 32 can be set so as to rotate in the same direction or in the opposite direction.

The cylinder jacket 42 is provided around a cylindrical space in which the two screws 31 and 32 are accommodated, and the cylinder wall can be maintained at a predetermined temperature by circulating a heat medium therein. The temperature can be arbitrarily adjusted by a temperature adjusting device (not shown) according to the temperature content, ambient temperature, and the like. Thereby, temperature adjustment of kneading | mixing of a primary kneading rubber and a silane coupling agent is attained.

The extrusion conditions of the twin screw extruder are preferably a screw diameter of 20 to 200 mm, a screw rotation speed of 20 to 400 rpm, and a screw L / D (screw length / screw diameter) of 5 to 100. When it is within the above range, shearing can be performed efficiently, and the coupling process can proceed well.

In the kneading step (step (II): second base kneading step) in the second rubber kneader, the temperature of the kneading material (kneading object) such as the primary kneading rubber and the silane coupling agent is 120 to 200 ° C. It is preferable to adjust to (more preferably 130 to 180 ° C.). The kneading time is preferably 0.5 to 5 minutes. By adjusting within the said range, the reaction rate of a silica and a silane coupling agent can be raised, and the coupling process of a silica and raw material rubber can advance efficiently. For this reason, excellent rubber physical properties (hardness, tensile strength, breaking strength, rolling resistance, wet grip performance, dry grip performance, etc.) can be imparted to the vulcanized rubber composition.
In the second rubber kneader, materials other than the primary kneaded rubber and the silane coupling agent may be kneaded as long as the effects of the present invention are not impaired.

In the cooling area 3c of FIG. 1, the secondary kneaded rubber obtained in the kneading area 3b is cooled to 120 ° C. or lower, for example. The cooling area is cooled by a well-known configuration (air cooling, water cooling, etc.).

After cooling the secondary kneaded rubber in the cooling area 3c, a sheet-like rubber is produced with a sheeting roll or the like, and is transferred to the cooling device 5 with a conveyor or the like. The apparatus 5 is cooled by a known cooling facility (water cooling, air cooling, etc.) and stored in a predetermined place until it is used in the next process.

A finishing kneading process is performed after the above-mentioned process. In the final kneading step, a vulcanizing agent (such as sulfur) and a vulcanization accelerator are kneaded together with the stored sheet-like rubber (secondary kneaded rubber) to obtain a tertiary kneaded rubber. The kneading method can be carried out by a conventionally known method such as a method using a closed rubber kneader such as the Banbury mixer of FIG. By the finish kneading step, an unvulcanized rubber composition can be obtained, and further vulcanized to produce a vulcanized rubber composition. Such a rubber composition can be suitably used for tire members such as treads, base treads, and sidewalls.

Moreover, a pneumatic tire can be manufactured by a normal method using the obtained rubber composition. That is, at the unvulcanized stage, the rubber composition is extruded in accordance with the shape of a tire member such as a tread, molded by a normal method on a tire molding machine, and bonded together with other tire members. Form a vulcanized tire. This unvulcanized tire can be heated and pressurized in a vulcanizer to produce a tire.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
SBR-1 (no modification): TUFDEN 3830 (Asahi Kasei Co., Ltd., 37.5 parts oil exhibition)
SBR-2 (with modification): SE0191 (manufactured by Sumitomo Chemical Co., Ltd.)
BR: BR150B (manufactured by Ube Industries)
Carbon Black (ISAF): Diamond Black I (Mitsubishi Chemical Corporation)
Silica: Nipsil AQ (manufactured by Tosoh Silica Co., Ltd.)
Silane coupling agent 1: Si266 (manufactured by Degussa)
Silane coupling agent 2: Si69 (manufactured by Degussa)
Oil: VIVETEC400 (manufactured by H & R)
Wax: Sannowax anti-aging agent manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylene produced by Ouchi New Chemical Co., Ltd.) Diamine)
Stearic acid: Tungsten zinc oxide manufactured by NOF Corporation: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. Noxeller CZ (N-cyclohexyl-2-benzothiazylsulfenamide)
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1-5
[First base kneading process]
In accordance with the formulation shown in Table 1, materials other than the silane coupling agent, sulfur, and vulcanization accelerator were kneaded using a Banbury mixer (BB270) manufactured by Kobe Steel Co., Ltd. to produce a primary kneaded rubber. The kneading conditions in the Banbury mixer are as follows.
(Kneading conditions)
Temperature of primary kneading rubber (kneading rubber): Kneading and kneading time: 3.5 minutes until reaching 155 ° C. Rotor rotation speed: 50 rpm

[Second base kneading process]
The primary kneaded rubber obtained in the first base kneading step is supplied to a twin screw extruder by a feed screw (2TR manufactured by Moriyama Co., Ltd.) and at the same time using a silane coupling agent injection device (injector type). According to the formulation shown in Table 1, a silane coupling agent was injected into the feed area of the extruder. Subsequently, the mixture was kneaded in a kneading area under the following kneading conditions to prepare a secondary kneaded rubber.
(Kneading conditions)
Screw diameter: 100mm
Screw rotation speed: 100rpm
Screw L / D: 40
Temperature of secondary kneaded rubber (kneaded rubber): adjusted to the temperature shown in Table 1 Kneading time: secondary kneaded rubber after kneading for the time shown in Table 1 is cooled to 120 ° C. in a cooling area, Molded into sheet rubber. Furthermore, it was transferred to a cooling device (batch off machine), and the secondary kneaded rubber was cooled to 40 ° C.

[Finish kneading process]
According to the formulation shown in Table 1, using the same Banbury mixer, the kneaded product (secondary kneaded rubber), sulfur, and vulcanization accelerator obtained in the second base kneading step were kneaded, and the third kneaded rubber (unvulcanized) A rubber composition) was obtained. The kneading conditions in the Banbury mixer are as follows.
(Kneading conditions)
Temperature of the tertiary kneaded rubber (unvulcanized rubber composition): Kneading and kneading time: 2.5 minutes until the temperature reaches 100 ° C. Rotor rotation speed: 25 rpm

Comparative Example 1
An unvulcanized rubber composition was produced by kneading in three stages with the same composition. In addition, 3 stage kneading | mixing was performed in the following processes.
[First base kneading process]
In accordance with the formulation shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded using the same Banbury mixer to produce a primary kneaded rubber. The obtained primary kneaded rubber was cooled to 40 ° C.
The kneading conditions in the Banbury mixer are as follows.
(Kneading conditions)
Temperature of primary kneading rubber (kneading rubber): Kneading and kneading time: 3.5 minutes until reaching 155 ° C. Rotor rotation speed: 50 rpm

[Second base kneading process]
According to the formulation shown in Table 1, using the same Banbury mixer, only the primary kneaded rubber obtained in the first base kneading step was kneaded to produce a secondary kneaded rubber. The obtained secondary kneaded rubber was cooled to 40 ° C.
The kneading conditions in the Banbury mixer are as follows.
(Kneading conditions)
Temperature of secondary kneaded rubber (kneaded rubber): Kneading and kneading time until 150 ° C .: 3 minutes Rotor rotation speed: 50 rpm

[Finish kneading process]
According to the formulation shown in Table 1, using the same Banbury mixer, the kneaded product (secondary kneaded rubber), sulfur, and vulcanization accelerator obtained in the second base kneading step were kneaded, and the third kneaded rubber (unvulcanized) A rubber composition) was obtained. The kneading conditions in the Banbury mixer are as follows.
(Kneading conditions)
Temperature of the tertiary kneaded rubber (unvulcanized rubber composition): Kneading and kneading time: 2.5 minutes until the temperature reaches 100 ° C. Rotor rotation speed: 25 rpm

Comparative Examples 2-3
Instead of injecting the silane coupling agent in the feed area of the extruder, an unvulcanized rubber composition was prepared in the same manner as in the example except that the silane coupling agent was added to the Banbury mixer in the first base kneading step.

[Production of vulcanized rubber sheet]
The unvulcanized rubber compositions obtained in Examples and Comparative Examples were press vulcanized at 150 ° C. for 30 minutes to obtain vulcanized rubber sheets.

[Manufacture of test tires]
Further, the obtained unvulcanized rubber composition was molded into a tread shape, bonded to another tire member, and vulcanized under the conditions of 150 ° C., 35 minutes, and 25 kgf to obtain a test tire (195 / 65R15 ) Was produced.

The following evaluation was performed using the processability in the above manufacturing (adherence at the rotor of the Banbury mixer, Mooney viscosity of unvulcanized rubber composition, scorch time), the prepared vulcanized rubber sheet, and the test tire. It was. Each test result is shown in Table 1.

<Close contact with Banbury mixer rotor>
Judgment was made based on the following criteria based on the kneading test.
Yes: There is rubber residue in the rotor No: No rubber residue in the rotor

<Mooney viscosity test (workability)>
According to JIS K 6300 “Testing method for unvulcanized rubber”, a temperature of 130 ° C. heated by preheating for 1 minute using a Mooney viscosity tester “Mooney Viscometer SMV-202” manufactured by Shimadzu Corporation Under conditions, the small rotor was rotated, and the Mooney viscosity (ML _{1 + 4} ) of the unvulcanized rubber composition was measured after 4 minutes. Furthermore, the time (scorch time (min)) for the viscosity of the unvulcanized rubber composition to rise by 10 points was measured. A smaller Mooney viscosity indicates superior processability, and a smaller scorch time indicates that early vulcanization occurs and is not preferable.

<Hardness>
Hardness (Hs) was measured according to JIS-K6253 using the vulcanized rubber sheet (length 30 mm × width 50 mm × height 15 mm) obtained above.

<Tensile test>
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Tensile Properties”, a tensile test was conducted using a No. 3 dumbbell, and the rupture strength (TB) of the vulcanized rubber specimen (vulcanized rubber sheet) ), Elongation at break (EB) was measured. Each unit is expressed in MPa and%.

<Viscoelasticity test>
A test piece of a predetermined size was prepared from the vulcanized rubber sheet, and was used under conditions of an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho Co., Ltd. The complex elastic modulus (E ^* ) and loss tangent (tan δ) of the rubber test piece at ° C were measured. The evaluation result is indicated by an index in which E ^{* of} Comparative Example 1 is 100, and the larger the index, the better the rigidity. Moreover, it shows with the index | exponent which sets tan-delta of the comparative example 1 to 100, and it shows that there is little hysteresis loss and there is little heat_generation | fever as the index | exponent is large.

<Measurement of remaining amount of silane coupling agent>
The kneaded rubber was analyzed by gas chromatography. Specifically, the amount of methanol generated by thermal decomposition was quantified, and the remaining amount was calculated.

<Steering stability>
The manufactured test tire is mounted on a Toyota Corolla, and it runs at 40-100 km / h on a test course. And wet road surface condition (skid number of about 50). Evaluation was made according to the following criteria.
◎: Grip and grip feel better ○: Standard △: Grip drop and grip feel worse

<Abrasion resistance test>
The manufactured test tire was mounted on a Toyota Corolla, the amount of decrease in the groove depth after traveling a predetermined course for 10,000 km was measured, and the travel distance when the groove depth decreased by 1 mm was calculated. Furthermore, the abrasion resistance index of Comparative Example 1 was set to 100, and the amount of decrease in the groove depth of each formulation was displayed as an index according to the following formula. In addition, it shows that it is excellent in abrasion resistance, so that an abrasion resistance index | exponent is large.
(Abrasion resistance index) = (travel distance when the groove depth of 1 mm decreases in each composition) / (travel distance when the groove of the tire of Comparative Example 1 decreases by 1 mm) × 100

In the examples, the remaining amount of the silane coupling agent was small compared to the conventional three-stage kneading (Comparative Example 1), and the reaction rate between silica and raw rubber could be increased. For this reason, breaking strength and elongation at break improved, and wear resistance and wet performance also improved. Moreover, the improvement of workability was also seen. Furthermore, in Comparative Examples 2 to 3 in which the silane coupling agent was added to the Banbury mixer, adhesion to the rotor occurred, and workability was inferior.

DESCRIPTION OF SYMBOLS 1 Sealed 1st rubber kneading machine 2 Feed screw 3 Second rubber kneading machine 3a Feed area 3b Kneading area 3c Cooling area 4 Silane coupling agent injection device 5 Cooling device 11 Banbury mixer 12 Stirring rotor 13 Mixing chamber 14 Discharge port 15 Kneading machine body 16 Input port 17 Vertical hole 18 Floating weight 19 Drop door 31, 32 Screw 41 Cylinder 42 Cylinder jacket

Claims (4)

A closed first rubber kneader for kneading raw rubber and silica;
A silica-mixed rubber kneading system comprising: a second rubber kneader capable of adjusting the temperature of a kneaded object for kneading the primary kneaded rubber discharged from the first rubber kneader and the silane coupling agent. In
The first rubber kneader is a Banbury mixer, the second rubber kneader is a continuous kneader,
The continuous kneader is provided with a feed area and a kneading area in order from the primary kneading rubber charging side, the silane coupling agent is supplied in the feed area, and at least the kneading object in the kneading area This is a kneading system for silica-blended rubber that allows temperature control of the product . Kneading system of the silica compounded rubber as claimed in claim 1, wherein the continuous kneader is a twin-screw continuous kneader. The silica-blended rubber kneading system according to claim 1 or 2, wherein the second rubber kneader is capable of adjusting the temperature of the object to be kneaded to 120 to 200 ° C. Step (I) of obtaining a primary kneaded rubber by kneading raw material rubber and silica using a hermetic first rubber kneader;
Step (II) of obtaining a secondary kneaded rubber by kneading the primary kneaded rubber and the silane coupling agent using a second rubber kneader different from the first rubber kneader and capable of adjusting the temperature of the kneaded object. In the kneading method of the silica-containing rubber characterized by having
The first rubber kneader is a Banbury mixer,
The second rubber kneader is provided with a feed area capable of supplying the silane coupling agent in order from the primary kneading rubber charging side, and a kneading area capable of kneading the primary kneading rubber and the silane coupling agent. A continuous kneader,
After the step (II) supplies the silane coupling agent in the feed area, at least in the kneading area of the second rubber kneader, the primary kneaded rubber as the kneading object and the silane coupling agent A method for kneading a silica-containing rubber, in which a mixture thereof is kneaded at 120 to 200 ° C.

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