JP2018177834A - Production method of rubber composition for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a rubber composition for a tire, by which a rubber composition for a tire can be obtained that has increased dispersibility of silica and is improved in wear resistance or the like, while achieving good processability.SOLUTION: The production method of a rubber composition for a tire includes: a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator; a finish kneading step of kneading a kneaded material 1 obtained by the base kneading step with a vulcanizing agent; and an extrusion step of extruding a kneaded material 2 obtained in the finish kneading step. The extrusion step is performed by controlling a screw temperature of an extruder to 50 to 90°C.SELECTED DRAWING: None

Description

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

In the rubber composition for tires, the technique which mix | blends a silica is widely used in order to improve performance, such as fuel economy, abrasion resistance, wet grip property, in a good balance.

Silica is highly cohesive and difficult to be uniformly dispersed in rubber, and therefore, it is generally used in combination with a silane coupling agent which binds to silica and promotes the dispersion of silica. Conventionally, in order to improve the dispersibility of silica, various methods for enhancing the reactivity of a silane coupling agent have been studied. For example, in Patent Document 1, a method of blending a hydroxy acid and itaconic acid in a rubber composition Is disclosed. In addition, as another method for enhancing the reactivity of the silane coupling agent, a method is also known in which a vulcanization accelerator, which is usually added in the final mixing step, is added together with the rubber component, silica and the silane coupling agent in the base mixing step. ing. However, in recent years, further improvement of the dispersibility of silica is required.

International Publication No. 2011/062099

The present invention solves the above problems and improves the dispersibility of silica while obtaining good processability, and a method for producing a rubber composition for a tire from which a rubber composition for a tire having improved abrasion resistance and the like can be obtained. Intended to provide.

The present invention comprises a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator, and a final kneading step of kneading the kneaded product 1 obtained in the base kneading step and a vulcanizing agent, And extruding step of extruding the kneaded material 2 obtained in the final kneading step, the extruding step relates to a method for producing a rubber composition for a tire, which is performed by adjusting the screw temperature of the extruder to 50 to 90 ° C.

According to the present invention, a base kneading step of kneading the rubber component, silica, a silane coupling agent and a vulcanization accelerator, and a final kneading step of kneading the kneaded product 1 obtained in the base kneading step and the vulcanizing agent An extrusion step of extruding the kneaded material 2 obtained in the final kneading step, wherein the extrusion step is a method for producing a rubber composition for a tire, which is performed by adjusting the screw temperature of the extruder to 50 to 90.degree. Since it exists, the dispersibility of a silica is improved and the rubber composition for tires by which abrasion resistance etc. were improved is obtained, obtaining favorable workability.

The present invention comprises a base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator, and a final kneading step of kneading the kneaded product 1 obtained in the base kneading step and a vulcanizing agent, And an extrusion step of extruding the kneaded material 2 obtained in the final kneading step, wherein the extrusion step is a method for producing a rubber composition for a tire which is carried out by adjusting the screw temperature of the extruder to 50 to 90 ° C.

When the kneaded material obtained in the kneading step is kneaded with an extruder, the reaction rate of the coupling agent is increased and the silica dispersibility is increased by setting the temperature control of the extruder to a higher temperature, but in the case of ordinary compounding There is a problem that burns occur. In the present invention, good processability is obtained by improving the silica dispersion by adding and kneading the vulcanization accelerator based on the base kneading, and further improving the silica dispersion by raising the screw temperature of the extruder. At the same time, silica dispersion can be significantly improved.

This is because mixing rubber of low viscosity can be obtained by charging the vulcanization accelerator based on the base, and thus heat generation can be suppressed. Therefore, since it is hard to burn even under high temperature conditions, screw temperature of the extruder can be raised. It is assumed that the silica dispersion is synergistically improved while obtaining good processability. Therefore, it is possible to synergistically improve the performance balance with the abrasion resistance etc. while preventing burnt and the like during kneading and obtaining good processability (kneading processability, extrusion processability).

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. Among them, SBR and BR are preferable, and combined use of SBR and BR is more preferable.

Although it does not specifically limit as a silane coupling agent, For example, a sulfide type, a vinyl type, an amino type, glycidoxy type, a nitro type, a chloro type silane coupling agent etc. are mentioned. One of these may be used alone, or two or more may be used in combination. Among them, sulfide-based silane coupling agents are preferable, and bis (3-triethoxysilylpropyl) tetrasulfide is more preferable.

The silica is not particularly limited, and those common 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 in accordance with ASTM D3037-81.

The vulcanization accelerator is not particularly limited, and examples thereof include guanidines, sulfenamides, thiazoles, thiurams, dithiocarbamates, thioureas, xanthogenates and the like. One of these may be used alone, or two or more may be used in combination. Among them, guanidines, sulfenamides, thiazoles and thiurams are preferable because the effects of the present invention can be obtained well.

As guanidines, 1,3-diphenylguanidine, 1,3-di-o-tolyl guanidine, 1-o-tolylbiguanide, di-o-tolyl guanidine salt of dicatechol borate, 1,3-di-o- Examples include cumenyl guanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionyl guanidine and the like. One of these may be used alone, or two or more may be used in combination. Among these, 1,3-diphenylguanidine and 1,3-di-o-tolyl guanidine are preferable.

As sulfenamides, N-cyclohexyl-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide and the like can be mentioned. One of these may be used alone, or two or more may be used in combination. Among them, N-cyclohexyl-2-benzothiazolylsulfenamide is preferable.

As thiazoles, 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzo Thiazole etc. are mentioned. One of these may be used alone, or two or more may be used in combination. Among them, 2-mercaptobenzothiazole and dibenzothiazyl disulfide are preferable.

Examples of thiurams include tetrakis (2-ethylhexyl) thiuram disulfide, tetrabenzylthiuram disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and the like. One of these may be used alone, or two or more may be used in combination. Among them, tetrakis (2-ethylhexyl) thiuram disulfide and tetrabenzylthiuram disulfide are preferable.

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

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

In the base kneading step, the amounts of the rubber component, the silica, the silane coupling agent and the vulcanization accelerator added may be all or a part thereof (total amount used in all steps).
It is preferable that the rubber component, silica and silane coupling agent are all introduced in the base kneading step and kneaded since the dispersion of silica can be further promoted, and the vulcanization accelerator is partially based on the kneading step It is preferable to charge and knead, and to charge and knead the remaining portion in the final kneading step.

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

In the base kneading step, the discharge temperature of the kneaded material 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 finishing and kneading step, the kneaded product 1 and the vulcanizing agent obtained in the base and kneading step are added and kneaded.

It does not specifically limit as a kneading method of a finishing kneading process, For example, well-known kneaders, such as an open roll, can be used. The discharge temperature of the kneaded material 2 is preferably 80 to 120 ° C.

The vulcanizing agent to be added in the finishing and kneading step is not particularly limited as long as it is a chemical which can crosslink the rubber component, and examples thereof include sulfur and the like. In addition, a hybrid crosslinking agent (organic crosslinking agent) can also be used as a vulcanizing agent in the present invention. One of these may be used alone, or two or more may be used in combination. Among them, sulfur is preferred.

In the finishing and kneading step, components other than the above-mentioned vulcanizing agent may be added and kneaded. As other components, for example, a vulcanization accelerator, zinc oxide and the like can be mentioned.

As the vulcanization accelerator to be added in the final kneading step, the same one as the vulcanization accelerator to be added in the base kneading step can be used, but guanidines, thiazoles and sulfenamides are preferable, and guanidines and thiazoles are preferable. More preferred is a combined use of sulfenamides.

(Extrusion process)
In the extrusion step, the kneaded material 2 obtained in the final kneading step is extruded into a sheet. The extrusion process can be carried out, for example, using an extruder having a cylinder and a screw known in the rubber field.

The extrusion process is performed by adjusting the screw temperature of the extruder to 50 to 90 ° C. That is, at the time of kneading (extrusion) of the kneaded material 2, the temperature of the screw provided in the extruder is adjusted to a predetermined range, and the extrusion process is performed. By setting the content to the lower limit or more, the coupling reaction proceeds and the silica dispersion tends to be improved. By setting the content to the upper limit or less, the texture of the rubber sheet can be improved, and the silica dispersion tends to be improved. The screw temperature is preferably 60 to 90 ° C, more preferably 70 to 85 ° C.

The temperature control of the screw of the extruder can be adjusted using a temperature control device constituted by a jacket for circulating warm water, a cooling device, a circulation pump, a heating device, a temperature sensor and the like. For example, the temperature control device is installed to the screw unit, and the temperature of hot water supplied to the jacket of the screw unit is adjusted by operating the cooling device or the heating device based on the result of temperature measurement of the hot water by the temperature sensor Thus, the temperature of the screw portion can be adjusted.

(Vulcanization process)
The kneaded material (unvulcanized rubber composition) produced in the above-mentioned steps is usually vulcanized thereafter. For example, an unvulcanized rubber composition is extruded according to the shape of a tire member such as a tread, molded by a usual method on a tire molding machine, and bonded together with other tire members, an unvulcanized tire The tire can be manufactured by applying heat and pressure in a vulcanizer after forming the. 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 content of silica is preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component because processability, abrasion resistance, etc. are obtained in a well-balanced manner. It is more preferably 60 parts by mass or more, and preferably 200 parts by mass or less, 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 processability, abrasion resistance, etc. are obtained in a well-balanced manner. The amount is preferably at least 8 parts by mass, more preferably at most 20 parts by mass, and more preferably at most 15 parts by mass.

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

Hereinafter, various medicines used by an example and a comparative example are summarized and explained.
SBR: Nippon Zeon Co., Ltd. Nipol NS210 (S-SBR)
BR: BR150B manufactured by Ube Industries, Ltd.
Silica: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by Evonik Degussa
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Carbon black: Diamond black N220 (N ₂ SA: 114 m ² / g) manufactured by Mitsubishi Chemical Corporation
Oil: Japan Energy Co., Ltd. X 140 (aroma oil)
Anti-aging agent: Noclac 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine) manufactured by Ouchi Emerging Chemical Industry Co., Ltd.
Stearic acid: Beads made by NOF Corporation, Ltd. Beads: Stearic acid agate vulcanization accelerator D: Nouchiseller D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Co., Ltd.
Vulcanization accelerator DT: Noxceler DT (1,3-di-o-tolyl guanidine) manufactured by Ouchi Emerging Chemical Industry Co., Ltd.
Vulcanization accelerator CZ: Noccellar CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Emerging Chemical Industry Co., Ltd.
Vulcanization accelerator MP: Noccellar MP (2-mercaptobenzothiazole) manufactured by Ouchi Shinko Chemical Co., Ltd.
Vulcanization accelerator TOT-N: Noccellar TOT-N (tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinko Chemical Co., Ltd.
Vulcanization accelerator TBZTD: Sansera TBZTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.
Vulcanization accelerator MBTS: Noxceler DM (dibenzothiazyl disulfide) manufactured by Ouchi Shinko Chemical Co., Ltd.
Zinc oxide: Zinc oxide from Mitsui Metal Mining Co., Ltd. Two types of sulfur: Powdered sulfur from Tsurumi Chemical Industry Co., Ltd.

(Example and Comparative Example)
(1) Base kneading process The material described in the item of the base kneading process of Tables 1-5 was knead | mixed using the Banbury mixer, and it discharged | emitted when rubber | gum temperature (temperature of kneading | mixing thing) became about 150 degreeC.
(2) Finishing and kneading step Using an open roll, the kneaded material 1 obtained in the base kneading step and the materials described in the item of finishing and kneading step in Tables 1 to 5 are kneaded to a rubber temperature of about 110 ° C. It was discharged when it became.
(3) Extrusion process Using the extruder (screw diameter: φ 80 mm, L / D: 50, die gap width: 40 mm), the kneaded product 2 obtained in the finishing and kneading step is operated at a screw rotation speed of 80 RPM and an extrusion speed of about The ribbon-like 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-cured with a 0.5 mm-thick mold for 10 minutes at 170 ° C. to obtain a vulcanized rubber composition.

The following evaluation was performed about the obtained vulcanized rubber composition and the unvulcanized rubber composition. The results are shown in Tables 1-5. The reference composition in each table is 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

(Dough skin)
The above unvulcanized rubber composition was extruded into a 1.0 mm-thick rubber sheet with a roll, and the state of the obtained rubber sheet was confirmed. In addition, those with no problem in the surface of the cloth were marked with ○, those with a little problem with Δ, and those without so with ×.

(Amount of unreacted silane coupling agent)
The unvulcanized rubber composition was finely cut and extracted in ethanol for 24 hours. The amount of unreacted silane coupling agent extracted in the extract solution was measured by gas chromatography, and the amount of unreacted silane coupling agent (wt%) was calculated from the amount of silane coupling agent added. The smaller this value is, the smaller the amount of the silane coupling agent unreacted in the unvulcanized rubber composition is, which indicates that the reaction of the silane coupling agent has progressed.

(Mooney viscosity)
The obtained unvulcanized rubber composition was measured at 130 ° C. in accordance with the measuring method of Mooney viscosity in accordance with JIS K6300. The value of the standard composition was indexed as 100. The larger the index, the lower the viscosity and the better the processability.

(Silica dispersion index)
Using the RPA 2000 manufactured by Alpha Technology, measure the strain dependence of the storage elastic modulus of the above-mentioned vulcanized rubber composition 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 storage elastic modulus at 0.56% strain was determined, and the index of the reference composition was set to 100 as an index. The larger the index, the less the dispersion failure of the silica, and the better the dispersion of the silica.

(Wear index)
The Lambourn's wear was measured using a Lambourn abrasion tester under the conditions of a temperature of 20 ° C., a slip ratio of 20% and a test time of 2 minutes, and the index of the reference composition was indicated as 100 as an index. The larger the wear index, the better the wear resistance.

From Tables 1 to 5, in the examples in which the vulcanization accelerator was kneaded by base kneading and the screw temperature of the extruder was adjusted to a predetermined range, the reaction rate of the silane coupling agent was high, and the dispersibility of silica was remarkable. It became clear that it improved and processability, abrasion resistance, etc. were improved with good balance.

Claims (1)

A base kneading step of kneading a rubber component, silica, a silane coupling agent and a vulcanization accelerator;
A final kneading step of kneading the kneaded product 1 obtained in the base kneading step and the vulcanizing agent;
And extruding the kneaded material 2 obtained in the finishing and kneading step,
The said extrusion process is a manufacturing method of the rubber composition for tires performed by adjusting the screw temperature of an extruder to 50-90 degreeC.