JP6958005B2 - Manufacturing method of rubber composition for tires - Google Patents

Description

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

In rubber compositions for tires, a technique of blending silica is widely used for the purpose of improving fuel efficiency and wet grip in a well-balanced manner.

Since silica has high cohesiveness and is difficult to disperse uniformly in rubber, it is generally used in combination with a silane coupling agent that binds to silica and promotes dispersion of silica. Conventionally, various methods for increasing the reactivity of a silane coupling agent have been studied in order to improve the dispersibility of silica. For example, in Patent Document 1, a method of blending a hydroxy acid and an itaconic acid into a rubber composition. Is disclosed. Further, as another method for increasing the reactivity of the silane coupling agent, a method in which the vulcanization accelerator, which is usually added in the finish kneading process, is added together with the rubber component, silica and the silane coupling agent in the base kneading process is also known. ing. However, in recent years, further improvement in the dispersibility of silica has been required.

International Publication No. 2011/06202099

The present invention solves the above problems, improves the dispersibility of silica while obtaining good workability, and provides a rubber composition for tires having improved fuel efficiency and wet grip performance in a well-balanced manner. It is an object of the present invention to provide a method for producing a composition.

The present invention comprises a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator, a finish kneading step of kneading the kneaded product 1 and the vulcanizing agent obtained in the base kneading step, and a cylinder. Including an extrusion step of extruding the kneaded product 2 obtained in the finish kneading step by an extruder equipped with a screw, the extrusion step adjusts the temperature difference between the cylinder and the screw to 12 to 33 ° C. The present invention relates to a method for producing a rubber composition for a tire.

According to the present invention, there is a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator, and a finish kneading step of kneading the kneaded product 1 and the vulcanizing agent obtained in the base kneading step. Including an extrusion step of extruding the kneaded product 2 obtained in the finish kneading step by an extruder equipped with a cylinder and a screw, the extrusion step adjusts the temperature difference between the cylinder and the screw to 12 to 33 ° C. Since this is a method for producing a rubber composition for tires, the rubber composition for tires has improved dispersibility of silica while obtaining good workability, and has improved fuel efficiency and wet grip performance in a well-balanced manner. Is obtained.

The present invention comprises a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator, a finish kneading step of kneading the kneaded product 1 and the vulcanizing agent obtained in the base kneading step, and a cylinder. Including an extrusion step of extruding the kneaded product 2 obtained in the finish kneading step by an extruder equipped with a screw, the extrusion step adjusts the temperature difference between the cylinder and the screw to 12 to 33 ° C. This is a method for producing a rubber composition for a tire.

When the kneaded product obtained in the kneading step is kneaded by an extruder, the reaction rate of the coupling agent can be further increased by raising the temperature of the screw to improve the dispersion of silica. Further, as the temperature difference between the screw and the cylinder increases, the discharge amount also increases. With ordinary compounds, there is a problem that burning is likely to occur when the temperature of the screw is raised.
In the present invention, the vulcanization accelerator is added and kneaded by the base kneading to improve the silica dispersion and reduce the compound viscosity, and even when the temperature of the screw is raised, discoloration is unlikely to occur, and the above effect is good. The dispersion of silica is remarkably improved while obtaining excellent processability.

This is because a low-viscosity compounded rubber can be obtained by adding a vulcanization accelerator as a base kneading, so that heat generation can be suppressed. Therefore, it is difficult to burn even under high share conditions, so the temperature difference between the screw and the cylinder is increased. This is due to the fact that the reaction rate of the coupling agent can be further increased under high temperature conditions, and it is presumed that this synergistically improves the silica dispersion while obtaining good processability. Therefore, it is possible to synergistically improve the performance balance between fuel efficiency and wet grip performance while preventing discoloration during kneading and obtaining good workability (kneading workability, extrusion workability).

The details of each step will be described below.

(Base kneading process)
In the base kneading step, the rubber component, silica, silane coupling agent and vulcanization accelerator are kneaded.

Examples of the rubber component include diene rubbers such as natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR). These may be used alone or in combination of two or more. Of these, SBR and BR are preferable, and the combined use of SBR and BR is more preferable.

The silane coupling agent is not particularly limited, and examples thereof include sulfide-based, vinyl-based, amino-based, glycidoxy-based, nitro-based, and chloro-based silane coupling agents. These may be used alone or in combination of two or more. Of these, a sulfide-based silane coupling agent is preferable, and bis (3-triethoxysilylpropyl) tetrasulfide is more preferable.

The silica is not particularly limited, and those commonly used in the tire industry can be used. The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 to 250 m ² / g, more preferably 120 to ²⁰⁰ m 2 / g.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

The vulcanization accelerator is not particularly limited, and examples thereof include guanidines, sulfenamides, thiazoles, thiurams, dithiocarbamate salts, thioureas, and xanthogenates. These may be used alone or in combination of two or more. Of these, guanidines, sulfenamides, thiazoles, and thiurams are preferable because the effects of the present invention can be obtained satisfactorily.

Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholbolate, and 1,3-di-o-. Examples thereof include cumenyl guanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine and the like. These may be used alone or in combination of two or more. Of these, 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine are preferable.

Examples of sulfenamides include N-cyclohexyl-2-benzothiazolyl sulfenamide, N, N-dicyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide, Examples thereof include N-oxydiethylene-2-benzothiazolyl sulfenamide and N-methyl-2-benzothiazolyl sulfenamide. These may be used alone or in combination of two or more. Of these, N-cyclohexyl-2-benzothiazolyl sulfeneamide is preferable.

Examples of thiazoles include 2-mercaptobenzothiazole (MBT), dibenzothiazil disulfide (MBTS), 2- (2,4-dinitrophenyl) mercaptobenzothiazole, and 2- (2,6-diethyl-4-moriholinothio) benzo. Thiazole and the like can be mentioned. These may be used alone or in combination of two or more. Of these, 2-mercaptobenzothiazole and dibenzothiazyl disulfide are preferable.

Examples of thiurams include tetrakis (2-ethylhexyl) thiuram disulfide, tetrabenzyl thiuram disulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, dipentamethylene thiuram tetrasulfide and the like. These may be used alone or in combination of two or more. Of these, tetrakis (2-ethylhexyl) thiuram disulfide and tetrabenzyl thiuram disulfide are preferable.

In the base kneading step, the amount of the vulcanization accelerator added should be set to 0.1 to 10 parts by mass with respect to 100 parts by mass of the added amount of silica from the viewpoint of the reaction promoting effect of the silane coupling agent and silica. Is preferable.

In the base kneading step, in addition to the above-mentioned rubber component, silica, silane coupling agent, and vulcanization accelerator, other components may be added and kneaded. The other components are not particularly limited as long as they are other than the vulcanizing agent added in the finish kneading step, and examples thereof include carbon black, oil, stearic acid, and an antiaging agent.

In the base kneading step, the amount of the rubber component, silica, silane coupling agent and vulcanization accelerator added may be the total amount (total amount used in the whole process) or a part thereof.
It is preferable to add all of the rubber component, silica and silane coupling agent in the base kneading process and knead them because the dispersion of silica can be further promoted, and part of the vulcanization accelerator is added in the base kneading process. It is preferable that the mixture is charged and kneaded, and the balance is charged and kneaded in the finishing kneading process.

As the kneader used in the base kneading process, a closed type Banbury mixer is preferable. The shape of the rotor of the Banbury mixer may be either a tangential type or a meshing type.

In the base kneading step, the discharge temperature of the kneaded product 1 is preferably 130 to 160 ° C. from the viewpoint of the reaction promoting effect of the silica and the silane coupling agent.

(Finishing process)
In the finish kneading step, the kneaded product 1 and the vulcanizing agent obtained in the base kneading step are added and kneaded.

The kneading method in the finish kneading step is not particularly limited, and for example, a known kneading machine such as an open roll can be used. The discharge temperature of the kneaded product 2 is preferably 80 to 120 ° C.

The vulcanizing agent to be added in the finish kneading step is not particularly limited as long as it is a chemical capable of cross-linking the rubber component, and examples thereof include sulfur and the like. Further, the hybrid cross-linking agent (organic cross-linking agent) can also be used as the vulcanizing agent in the present invention. These may be used alone or in combination of two or more. Of these, sulfur is preferable.

In the finish kneading step, other components may be added and kneaded in addition to the above-mentioned vulcanizing agent. Examples of other components include vulcanization accelerators, zinc oxide and the like.

As the vulcanization accelerator added in the finish kneading step, the same vulcanization accelerator added in the base kneading step can be used, but guanidines, thiazoles and sulfenamides are preferable, and guanidines and thiazoles are preferable. , Sulfenamides are more preferable in combination.

(Extrusion process)
In the extrusion step, an extruder equipped with a cylinder and a screw is used to extrude the kneaded product 2 obtained in the finish kneading step into a sheet shape. In the extrusion process, an extruder having a cylinder and a screw known in the rubber field can be used.

The extrusion process is performed by adjusting the temperature difference between the cylinder and the screw to 12 to 33 ° C. By setting the temperature difference to the lower limit or higher, the compound viscosity tends to be lowered and the silica dispersion tends to be improved. By setting the content below the upper limit, the texture of the rubber sheet tends to be improved and the silica dispersion tends to be improved. The temperature difference is preferably 15 to 30 ° C. Normally, the cylinder is adjusted to a higher temperature than the screw.

In the extrusion step, the temperature of the cylinder is preferably adjusted to 30 to 100 ° C., more preferably 35 to 80 ° C., still more preferably 40 to 70 ° C. from the viewpoint of silica dispersibility and processability. The temperature of the screw is preferably adjusted to 40 to 120 ° C., more preferably 50 to 100 ° C., and even more preferably 60 to 95 ° C. from the viewpoint of silica dispersibility and workability.

The temperature of the cylinder and screw of the extruder can be adjusted by using a temperature adjusting device including a jacket for circulating hot water, a cooling device, a circulation pump, a heating device, a temperature sensor, and the like. For example, a temperature control device is installed on each part of the screw part and the cylinder part, and the cooling device and the heating device are operated based on the result of the temperature measurement of the hot water by the temperature sensor to supply the hot water to the jacket of each part. By adjusting the temperature, the temperature of the screw part and the cylinder part can be adjusted individually.

(Vulcanization process)
The kneaded product (unvulcanized rubber composition) produced in the above step is usually vulcanized afterwards. For example, an unvulcanized rubber composition is extruded according to 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 to form an unvulcanized tire. The tire can be manufactured by heating and pressurizing in a vulcanizer after forming the tire. The vulcanization temperature is preferably 130 to 200 ° C., and the vulcanization time is preferably 5 to 15 minutes.

In the rubber composition obtained by the production method of the present invention, the silica content is preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component because low fuel consumption and wet grip performance can be obtained in a well-balanced manner. , More preferably 60 parts by mass or more, preferably 200 parts by mass or less, and more preferably 100 parts by mass or less.

In the rubber composition obtained by the production method of the present invention, the content of the silane coupling agent is preferably 5 parts by mass with respect to 100 parts by mass of silica because fuel efficiency and wet grip performance can be obtained in a well-balanced manner. It is more than parts, more preferably 8 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Hereinafter, various chemicals used in Examples and Comparative Examples will be collectively described.
SBR: Nippon Zeon Co., Ltd. Nipol NS210 (S-SBR)
BR: BR150B manufactured by Ube Industries, Ltd.
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Carbon black: Diamond black N220 (N ₂ SA: ^{114m 2} / g) manufactured by Mitsubishi Chemical Corporation
Oil: X140 (aroma oil) manufactured by Japan Energy Co., Ltd.
Anti-aging agent: Nocrack 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Stearic acid: Beads made by NOF CORPORATION Stearic acid Tsubaki vulcanization accelerator D: Noxeller D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazolyl sulfeneamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator MP: Noxeller MP (2-mercaptobenzothiazole) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator TOT-N: Noxeller TOT-N (Tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator TBZTD: Sunseller TBZTD (Tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.
Vulcanization accelerator MBTS: Noxeller DM (dibenzothiazil disulfide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Zinc oxide: Zinc oxide type 2 manufactured by Mitsui Metal Mining Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

(Examples and comparative examples)
(1) Base kneading process The materials listed in the items of the base kneading process in Tables 1 to 5 were kneaded using a Banbury mixer, and discharged when the rubber temperature (temperature of the kneaded product) reached about 150 ° C.
(2) Finish kneading process Using an open roll, the kneaded product 1 obtained in the base kneading process and the materials listed in the items of the finish kneading process in Tables 1 to 5 are kneaded to bring the rubber temperature to about 110 ° C. It was discharged when it became.
(3) Extrusion process Using an extruder (screw diameter: φ80 mm, L / D: 50, die gap width: 40 mm), the kneaded product 2 obtained in the finish kneading process has a screw rotation speed of 80 RPM and an extrusion speed of about. A ribbon-shaped sheet was extruded at 9 m / min to obtain an unvulcanized rubber composition. The cylinder temperature and screw temperature of each example and comparative example are as described in each table.
(4) Vulcanization Step The unvulcanized rubber composition obtained in the extrusion step was press-vulcanized at 170 ° C. for 10 minutes with a mold having a thickness of 0.5 mm to obtain a vulcanized rubber composition.

The obtained vulcanized rubber composition and unvulcanized rubber composition were evaluated as follows. The results are shown in Tables 1-5. The standard formulations in each table are as follows.
Table 1: Comparative Example 1-1
Table 2: Comparative Example 2-1
Table 3: Comparative Example 3-1
Table 4: Comparative Example 4-1
Table 5: Comparative Example 5-1

(Fabric skin)
The unvulcanized rubber composition was extruded into a rubber sheet having a thickness of 1.0 mm with a roll, and the state of the obtained rubber sheet dough was confirmed. Those with no cuts in the ears and no problems with the skin of the fabric are marked with ○, those with some problems are marked with △, and those without problems are marked with ×.

(Moony Viscosity Index)
The obtained unvulcanized rubber composition was measured at 100 ° C. according to the method for measuring Mooney viscosity according to JIS K6300. The value of the reference compound was set as 100 and displayed as an index. The larger the index, the lower the viscosity and the better the workability.

(Silica dispersion index)
Using RPA2000 manufactured by Alfer Technology Co., Ltd., the strain dependence of the storage elastic modulus of the vulcanized rubber composition was measured under the conditions of a measurement temperature of 110 ° C. (preheating 1 minute), a frequency of 6 cpm, and an amplitude of 0.28 to 10%. The value of the storage elastic modulus when the strain amount was 0.56% was obtained, and the value of the reference compound was set as 100 and displayed as an index. The larger the index, the less the silica is poorly dispersed, indicating that the silica is well dispersed.

(RR index)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition under the conditions of a temperature of 30 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%. Was measured, and the reference composition was set as 100 and displayed as an index. The larger the index, the lower the rolling resistance and the better the fuel efficiency.

(WET index)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was obtained under the conditions of a temperature of 0 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%. Was measured, and the reference composition was set as 100 and displayed as an index. The larger the index, the larger the coefficient of friction on the wet road surface, indicating that the wet grip performance is excellent.

From Tables 1 to 5, in the examples in which the vulcanization accelerator was kneaded by the base kneading and the temperature difference between the cylinder and the screw of the extruder was adjusted within a predetermined range, the dispersibility of silica was remarkably improved and the fuel consumption was low. It was also clarified that the wet grip performance was improved in a well-balanced manner. In addition, good workability (kneading workability, extrusion workability) was also obtained.

Claims (5)

Base kneading process for kneading rubber components, silica, silane coupling agent and vulcanization accelerator,
A finish kneading step of kneading the kneaded product 1 and the vulcanizing agent obtained in the base kneading step, and a finishing kneading step.
The kneaded product 2 obtained in the finish kneading step includes an extrusion step in which the kneaded product 2 containing a vulcanizing agent is put into an extruder equipped with a cylinder and a screw and extruded.
The extrusion step is a method for producing a rubber composition for a tire, which is carried out by adjusting the temperature difference between the cylinder and the screw to 12 to 33 ° C. Contains styrene butadiene rubber, butadiene rubber and silica
The method for producing a rubber composition for a tire according to claim 1, wherein the rubber composition having a silica content of 70 parts by mass or more with respect to 100 parts by mass of the rubber component is produced. In the base kneading step, at least one selected from the group consisting of N-cyclohexyl-2-benzothiazolyl sulfeneamide, 2-mercaptobenzothiazole, tetrakis (2-ethylhexyl) thiuram disulfide and tetrabenzyl thiuram disulfide is kneaded. The method for producing a rubber composition for a tire according to claim 1 or 2. The base kneading step kneads styrene-butadiene rubber and butadiene rubber.
The method for producing a rubber composition for a tire according to any one of claims 1 to 3, wherein the finishing kneading step kneads zinc oxide. The base kneading step kneads styrene-butadiene rubber and butadiene rubber.
The rubber composition for a tire according to any one of claims 1 to 4, wherein the finishing kneading step kneads at least one selected from the group consisting of dibenzothiazyl disulfide and N-cyclohexyl-2-benzothiazolyl sulfeneamide. Manufacturing method of things.