JP2018177835A - 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 high mileage property and wet grip performance in a balanced manner, while achieving good processability.SOLUTION: The production method of a rubber composition for a tire includes: a first base kneading step of kneading a rubber component, silica and a silane coupling agent; a second base kneading step of kneading a first kneaded material obtained in the first base kneading step with a vulcanization accelerator; a finish kneading step of kneading a second kneaded material obtained in the second base kneading step with a vulcanizing agent; and an extrusion step of extruding a third kneaded material 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 fuel economy and wet grip property with sufficient 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-mentioned problems, improves the dispersibility of silica while obtaining good processability, and provides a rubber composition for a tire from which the low fuel consumption and wet grip performance are improved in a well-balanced manner. It is an object of the present invention to provide a method of producing a composition.

The present invention comprises a first base kneading step of kneading a rubber component, silica and a silane coupling agent, and a second base kneading step of kneading the first kneaded product and the vulcanization accelerator obtained in the first base kneading step. And a final kneading step of kneading the second kneaded material obtained in the second base kneading step and the vulcanizing agent, and an extrusion step of extruding the third kneaded material obtained in the final kneading step. A process relates to the manufacturing method of the rubber composition for tires performed by adjusting the screw temperature of an extruder to 50-90 ° C.

According to the present invention, the first base kneading step of kneading the rubber component, the silica and the silane coupling agent, and the second base of kneading the first kneaded product and the vulcanization accelerator obtained in the first base kneading step A final kneading step of kneading the second kneaded product obtained in the second base kneading step and the vulcanizing agent, and an extruding step of extruding the third kneaded material obtained in the final kneading step; Since 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, the dispersibility of a silica is improved, obtaining favorable processability, and low. A rubber composition for a tire having well-balanced fuel economy and wet grip performance can be obtained.

The present invention comprises a first base kneading step of kneading a rubber component, silica and a silane coupling agent, and a second base kneading step of kneading the first kneaded product and the vulcanization accelerator obtained in the first base kneading step. And a final kneading step of kneading the second kneaded material obtained in the second base kneading step and the vulcanizing agent, and an extrusion step of extruding the third kneaded material obtained in the final kneading step. A process is a manufacturing method of a rubber composition for tires performed by adjusting screw temperature of an extruder to 50-90 ° 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 balance of low fuel consumption and wet grip performance while preventing burn and the like during kneading to obtain good processability (kneading processability, extrusion processability).

The details of each step will be described below.
(First base kneading process)
In the first base kneading step, the rubber component, silica and a silane coupling agent 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.

In the first base kneading step, the input amounts of the rubber component, the silica and the silane coupling agent may be all (total amount used in all steps) or may be a part.
It is preferable to add and knead | mix the whole rubber component in a 1st base kneading process from the reason that dispersion of a silica can be promoted more, and a silica and a silane coupling agent introduce | transduce a part at a 1st base kneading process It is preferable to knead the mixture and to charge the remaining part in the second base kneading step.

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

The kneading in the first base kneading step can be carried out using a known kneader, and for example, is preferably carried out using a closed Banbury mixer. The shape of the Banbury mixer rotor may be either tangential or meshing.

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

(2nd base kneading process)
In the second base kneading step, the first kneaded product and the vulcanization accelerator obtained in the first base kneading step are kneaded.

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 second base kneading step, the input amount of the vulcanization accelerator may be the entire amount (total amount used in all steps) or may be a part, but the dispersion of silica can be further promoted. From the reason, it is preferable to partially charge and knead in the second base kneading step, and to charge and knead the remaining portion in the final kneading step.
Further, from the viewpoint of the reaction promoting effect of the silane coupling agent and the silica, the amount of the vulcanization accelerator to be added is preferably set to 0.1 to 10 parts by mass with respect to 100 parts by mass of the amount of silica added.

In the second base kneading step, components other than the above-described first kneaded product 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 silica, a silane coupling agent, an oil, stearic acid, an antiaging agent and the like.

The kneading in the second base kneading step can be carried out using a known kneader, and can be carried out using, for example, a closed Banbury mixer similar to the first base kneading step.

In the second base kneading step, the discharge temperature of the second kneaded material 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 final kneading step, the second kneaded product and the vulcanizing agent obtained in the second base kneading step are 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 third kneaded material 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 third kneaded product 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 the kneading | mixing (extrusion) of a 3rd kneaded material, the temperature of the screw with which the extruder is equipped is adjusted to a predetermined range, and an extrusion process is implemented. 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 55 to 85 ° C, more preferably 60 to 80 ° 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 manufacturing method of the present invention, the content of the silica is preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component because the fuel economy and wet grip performance are obtained in a balanced manner. More preferably, it is 60 mass parts or more, Preferably, it is 200 mass parts or less, More preferably, it is 100 mass parts 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 the silica because the fuel economy and the wet grip performance are obtained in a 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) First base kneading process The materials described in the item of the first base kneading process in Tables 1 to 5 are kneaded using a Banbury mixer, and the time when the rubber temperature (temperature of the kneaded material) reaches about 150 ° C. Was discharged.
(2) Second base kneading process Using the Banbury mixer, the first kneaded product obtained in the first base kneading process and the materials described in the item of the second base kneading process in Tables 1 to 5 are kneaded, It was discharged when the rubber temperature reached about 150 ° C.
(3) Finish kneading step Using the open roll, the second kneaded product obtained in the second base kneading step and the materials described in the item of finish kneading step in Tables 1 to 5 are kneaded, and the rubber temperature is about It was discharged when it reached 110 ° C.
(4) Extrusion process The third kneaded material obtained in the finishing and kneading process is extruded using an extruder (screw diameter: φ 80 mm, L / D: 50, die gap width: 40 mm), screw rotation speed 80 RPM, extrusion speed The ribbon-like sheet was extruded at about 9 m / min to obtain an unvulcanized rubber composition. In addition, screw temperature of each Example and a comparative example is as having indicated in each table.
(5) 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 problems in the surface of the fabric and those with no problems in 生地 and △, but with practically no problems were marked with Δ, and those with practical problems were indicated with ×.

(Amount of unreacted 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.

(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.

(RR index)
Loss tangent (tan δ) of the above-mentioned vulcanized rubber composition under the conditions of temperature 50 ° C., frequency 10 Hz, initial strain 10% and dynamic strain 2% using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) Were measured, and the index ratio was indexed to 100. The larger the index, the lower the rolling resistance and the better the fuel economy.

(WET index)
Loss tangent (tan δ) of the above-mentioned vulcanized rubber composition under the conditions of temperature 0 ° C., frequency 10 Hz, initial strain 10% and dynamic strain 2% using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) Were measured, and the index ratio was indexed to 100. The larger the index, the larger the coefficient of friction on a wet road surface, and the better the wet grip performance.

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 the fuel efficiency and wet grip performance were improved in a well-balanced manner. In addition, good processability (extrusion processability) was also obtained.

Claims (1)

A first base kneading step of kneading a rubber component, silica and a silane coupling agent;
A second base kneading step of kneading the first kneaded product and the vulcanization accelerator obtained in the first base kneading step;
A final kneading step of kneading the second kneaded product and the vulcanizing agent obtained in the second base kneading step;
And extruding the third kneaded material obtained in the final 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.