JP6379558B2 - Method for producing rubber composition for tire - Google Patents

Description

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

  In order to improve the fuel efficiency of a vehicle, it is required to reduce the rolling resistance of a pneumatic tire. At the same time, it is necessary for pneumatic tires to ensure sufficient steering stability and wet performance. In general, a rubber composition for tires containing silica in order to improve low rolling resistance and wet performance is known. However, if a part of the carbon black is replaced with silica, there is a concern that the rubber hardness is lowered and the steering stability is lowered. For this reason, it has been proposed to incorporate silica having a large nitrogen adsorption specific surface area (see, for example, Patent Document 1). However, the demand level for the tire performance of consumers is higher, and further improvements are expected.

  On the other hand, dry silica is known as silica having a large nitrogen adsorption specific surface area. Dry silica has a smaller primary aggregate (minimum constituent) and a larger nitrogen adsorption specific surface area than wet silica generally used in rubber compositions for tires. However, since dry silica is very bulky and fluffy, it tends to scatter when trying to knead into rubber, and is easy to agglomerate even if mixed. This was industrially difficult. For this reason, blending dry silica with a tire rubber composition has not been performed in practice.

JP 2013-166862 A

  An object of the present invention is to provide a method for producing a rubber composition for tires, which improves the mixing processability of dry silica and improves the dispersibility to a level higher than the conventional level.

The method for producing a rubber composition for a tire according to the present invention that achieves the above object is a method for producing a rubber composition for a tire in which 5 to 100 parts by weight of dry silica and a plasticizer component are blended with 100 parts by weight of a diene rubber. The plasticizer component comprises a silane coupling agent and at least one selected from oil, processing aid, and alkylsilane, and after premixing the plasticizer component and the dry silica in a mixer , the diene rubber was poured into the mixer, characterized by mixing.

Method for producing a rubber composition for a tire of the present invention includes a pre-silane coupling agents, oils, processing aids, and or plasticizer component and fumed silica consisting of alkyl silanes were premixed in a mixer, the mixer Since the diene rubber is added to and mixed with the diene rubber , it is possible to suppress the scattering of the dry silica during kneading and improve the mixing processability, and to disperse the dry silica well in the diene rubber. Thereby, the reinforcing performance and low rolling resistance of silica with respect to the diene rubber can be improved to a level higher than the conventional level.

The nitrogen adsorption specific surface area of dry silica is preferably more than 160 m ² / g and 500 m ² / g or less. Furthermore, at the time of preliminary mixing, it is preferable to blend 1 to 500% by weight of the plasticizer component based on the weight of dry silica. As the alkylsilane, alkyltriethoxysilane having an alkyl group having 7 to 20 carbon atoms is preferable. Further, when the mixture of dry silica and plasticizer component and the diene rubber are mixed, wet silica may be added and mixed at the same time.

  The method for producing a rubber composition for a tire according to the present invention includes a premixing step in which dry silica and a plasticizer component are mixed in advance, and a kneading step in which a mixture of the obtained dry silica and plasticizer component is mixed with a diene rubber. Have. In the kneading step, other compounding agents excluding the plasticizer component can be added and mixed together with the diene rubber. In addition, it is preferable to divide a vulcanization type compounding agent among other compounding agents and to mix at a lower temperature.

  In the premixing step of the present invention, dry silica and a plasticizer component are mixed. By mixing the plasticizer component with the dry silica, the bulk of the dry silica can be reduced and can be easily kneaded into the diene rubber. Dry silica is amorphous silicon dioxide produced by a dry method, and has fewer silanol groups (density) on the particle surface than wet silica. The dry silica used in the present invention should have a primary aggregate (minimum constituent) size smaller than that of the ultrafine type wet silica, that is, a specific surface area larger than that of wet silica. Is preferred.

The nitrogen adsorption specific surface area of the dry silica is preferably more than 160 m ² / g and 500 m ² / g or less, more preferably 180 to 450 m ² / g, and even more preferably 200 to 400 m ² / g. When the nitrogen adsorption specific surface area is less than 160 m ² / g, the difference in performance from a rubber composition in which wet silica having the same primary aggregate size is highly dispersed is reduced. On the other hand, when the nitrogen adsorption specific surface area exceeds 500 m ² / g, the mixing processability decreases. The nitrogen adsorption specific surface area of the dry silica is a value measured according to JIS K6217-2.

  In the tire rubber composition obtained by the production method of the present invention, the amount of dry silica is 5 to 100 parts by weight, preferably 5 to 80 parts by weight, more preferably 5 to 60 parts by weight based on 100 parts by weight of the diene rubber. Weight part. If the amount of dry silica is less than 5 parts by weight, the effect of reducing the rolling resistance cannot be sufficiently obtained, and the reinforcement to rubber cannot be sufficiently improved. Moreover, when the compounding quantity of a dry silica exceeds 100 weight part, mixing workability will fall. Furthermore, the reinforcement with respect to rubber | gum falls on the contrary.

  The plasticizer component premixed with the dry silica described above necessarily includes a silane coupling agent, and additionally contains at least one selected from oil, processing aid, and alkylsilane. By blending a silane coupling agent, the mixing processability of dry silica can be improved, the dispersibility of the diene rubber can be improved, and the reinforcement of the rubber can be enhanced.

  The type of the silane coupling agent is not particularly limited as long as it can be used for the rubber composition containing silica. For example, bis- (3-triethoxysilylpropyl) tetrasulfide, bis (3- Sulfur-containing silane coupling agents such as (triethoxysilylpropyl) disulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane can be exemplified. .

  The amount of the silane coupling agent is preferably 3 to 30% by weight, more preferably 4 to 15% by weight, based on the total amount of dry silica and wet silica. When the compounding amount of the silane coupling agent is less than 3% by weight of the silica compounding amount, the dispersion of dry silica and wet silica cannot be improved sufficiently. When the compounding amount of the silane coupling agent exceeds 15% by weight of the silica compounding amount, the silane coupling agents condense and the desired hardness and strength in the rubber composition cannot be obtained.

  The plasticizer component to be premixed with dry silica is not limited to the silane coupling agent described above, and it is necessary to add at least one selected from oil, processing aid, and alkylsilane. Oils, processing aids, and alkylsilanes that are usually blended into tire rubber compositions can be used.

  Examples of the oil include aroma oil, paraffin oil, naphthenic oil and the like. These may be used alone or in combination of two or more.

  The oil is preferably blended in an amount of 3 to 300% by weight, more preferably 5 to 200% by weight, based on the weight of the dry silica, and premixed.

  Examples of processing aids include polyalkylene glycols, fatty acid metal salts, fatty acid amides, amide esters, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, and the like. . These may be used alone or in combination of two or more.

  The processing aid is preferably added in an amount of 0.1 to 50% by weight, more preferably 0.5 to 20% by weight, based on the weight of dry silica, and premixed.

  In the production method of the present invention, by blending alkylsilane, aggregation of silica and increase in viscosity of the rubber composition can be suppressed, and rolling resistance and wet performance can be further improved.

  As the alkylsilane, alkyltriethoxysilane having an alkyl group having 7 to 20 carbon atoms is preferable. As a C7-20 alkyl group, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl Groups. Among these, from the viewpoint of compatibility with the diene rubber, an alkyl group having 8 to 10 carbon atoms is more preferable, and an octyl group and a nonyl group are further preferable.

  The alkylsilane is preferably mixed in an amount of 0.1 to 50% by weight, more preferably 0.5 to 30% by weight, based on the weight of the dry silica, and premixed.

  The total amount of the plasticizer component consisting of the silane coupling agent, oil, processing aid, and alkylsilane described above is preferably 1 to 500% by weight, more preferably 3.1 to the weight of dry silica. It is 400% by weight, more preferably 6 to 300% by weight. When the total amount of the plasticizer components is less than 3% by weight, the mixed processability of dry silica cannot be improved. On the other hand, when the total amount of the plasticizer components exceeds 500% by weight, the reinforcing property and low rolling resistance (tan δ at 60 ° C.) to the diene rubber are deteriorated.

  The mixer used in the preliminary mixing step is not particularly limited as long as it can mix dry silica and a plasticizer component. Preferably, dry silica and a plasticizer component are premixed in a mixer, and then a diene rubber and other compounding agents are charged into the mixer so that they can be mixed and kneaded. Examples of the mixer used in the preliminary mixing step include a Banbury mixer, a kneader, a meshing mixer, and a Henschel mixer.

  The mixing conditions in the preliminary mixing step are not particularly limited, and the temperature, the number of rotations, and the like can be appropriately determined so that the dry silica and the plasticizer component are mixed substantially uniformly.

  The method for producing a rubber composition for a tire of the present invention includes a kneading step of mixing and kneading a mixture of dry silica and a plasticizer component obtained in the preliminary mixing step and a diene rubber.

  In the present invention, examples of the diene rubber include styrene butadiene rubber, butadiene rubber, natural rubber, isoprene rubber, acrylonitrile butadiene rubber, butyl rubber, ethylene-propylene-diene rubber, and chloroprene rubber. Of these, styrene butadiene rubber, butadiene rubber, and natural rubber are preferable. The content ratio of each diene rubber is not particularly limited, and can be appropriately selected depending on the required characteristics of the tire member to be applied.

  In the kneading step, other compounding agents excluding the plasticizer component can be added together with the diene rubber. Other compounding agents include other reinforcing fillers other than dry silica, vulcanization or crosslinking agents, vulcanization accelerators, anti-aging agents, liquid polymers, thermosetting resins, and other rubber compositions for tires in general. Various compounding agents used can be illustrated. The compounding amounts of these compounding agents can be conventional conventional compounding amounts as long as the object of the present invention is not violated.

  Examples of other reinforcing fillers include wet silica, carbon black, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, and titanium oxide. Of these, wet silica and carbon black are preferred.

  By blending wet silica, the silica reinforcing performance, low rolling resistance and processability with respect to the diene rubber can be balanced at a high order. The amount of wet silica is preferably 5 to 150 parts by weight, more preferably 10 to 120 parts by weight, based on 100 parts by weight of the diene rubber.

  Further, the ratio [Wa / (Wa + Wb)] of the dry silica compounding amount (Wa) to the total (Wa + Wb) of the dry silica compounding amount (Wa) and the wet silica compounding amount (Wb) is preferably 0.05 to 0. .95, more preferably 0.10 to 0.85, still more preferably 0.10 to 0.75.

  By blending carbon black, the hardness, strength and wear resistance of the rubber composition can be increased. The compounding amount of the carbon black is preferably 3 to 50 parts by weight, more preferably 5 to 40 parts by weight with respect to 100 parts by weight of the diene rubber.

  Vulcanizing compounding agents such as a vulcanization or crosslinking agent and a vulcanization accelerator are preferably mixed at a low temperature so that vulcanization does not proceed during kneading and mixing. For this reason, the kneading process is divided into two stages. First, a mixture of dry silica and a plasticizer component, and other compounding agents excluding diene rubber and vulcanizing compounding agent are mixed, kneaded, cooled, and then added. It is better to add and mix a sulfur compounding agent. The mixing method of the vulcanizing compounding agent may be performed in accordance with a normal method.

  In the kneading step, as a kneading machine, a normal rubber kneading machine such as a Banbury mixer, a meshing mixer, a kneader, a roll, or the like can be used.

  As the kneading conditions in the kneading step, normal conditions such as separation of mixing of the vulcanizing compounding agent as described above can be applied.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  16 types of tire rubber compositions (Examples 1 to 8, Standard Examples, Comparative Examples 1 to 7) comprising the compounding agents shown in Table 3 as a common compounding and comprising the premixing step and the kneading step shown in Tables 1 and 2 ) Was prepared. First, silica and a plasticizer component in the column of the premixing step shown in Tables 1 and 2 were mixed for 3 minutes with a 1.7 L closed Banbury mixer (premixing step). Next, the components described in the column of the kneading step (excluding sulfur and the vulcanization accelerator) and the common compounding agents shown in Table 3 were added to this closed Banbury mixer and kneaded for 6 minutes. The kneaded master batch was discharged and allowed to cool to room temperature. The master batch was returned to a 1.7 L closed Banbury mixer, and sulfur and a vulcanization accelerator were added and mixed to produce a rubber composition for a tire (kneading step). In addition, in the column of styrene butadiene rubber (SBR) in Tables 1 and 2, the amount of net SBR excluding oil-extended components is shown in parentheses in addition to the amount of product. Moreover, the compounding quantity of the compounding agent described in Table 3 was shown by the weight part with respect to 100 weight part of diene rubber described in Tables 1 and 2.

In addition, in the kneading process, as the mixing processability of the dry silica, the time taken into the diene rubber (the time until the silica scatters) was measured and evaluated according to the following criteria. It can be considered that it can be industrially produced if the obtained results have a score of 3 or more shown in Tables 1 and 2.
5: Silica rubber uptake time less than 120 seconds 4: Silica rubber uptake time between 120 seconds and less than 180 seconds 3: Silica rubber uptake time between 180 seconds and less than 240 seconds 2: Silica rubber Up to 240 seconds or more and less than 300 seconds 1: Uptake time of silica into rubber is 300 seconds or more

  The obtained 16 kinds of rubber compositions were press vulcanized at 170 ° C. for 10 minutes in a predetermined mold to prepare test pieces made of a rubber composition for tires. The reinforcing properties and tan δ (60 ° C.) of the obtained test pieces were evaluated by the following methods.

Reinforcing (M300 / M100)
From the obtained test piece, a JIS No. 3 dumbbell-type test piece based on JIS K6251 was cut out. Using this test piece, a tensile test is performed based on JIS K6251, the stress at 100% elongation (M100) and the stress at 300% elongation (M300) are measured, and the ratio of these stresses (M300 / M100) is calculated. did. The obtained results are shown in the column of “Reinforcing (M300 / M100)” in Tables 1 and 2 as an index with the value of the standard example as 100. The larger this value, the better the reinforcing property for rubber.

tan δ (60 ° C)
The dynamic viscoelasticity of the obtained test piece was measured with a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd. at an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz, and tan δ at an ambient temperature of 60 ° C. was measured. . The obtained results are expressed as an index with the value of the standard example being 100, and are shown in the column of “tan δ (60 ° C.)” in Tables 1 and 2. The smaller this value, the smaller the rolling resistance and the better the fuel efficiency.

The types of raw materials used in Tables 1 and 2 are shown below.
SBR: Styrene butadiene rubber, E581 manufactured by Asahi Kasei Co., Ltd. Oil-extended product in which 37.5 parts by weight of oil-extended components are blended with 100 parts by weight of styrene butadiene rubber. BR: butadiene rubber, Nipol BR1220 manufactured by Nippon Synthetic Rubber Co., Ltd.
-Dry silica 1: Dry silica, QS-30 manufactured by Tokuyama Corporation, nitrogen adsorption specific surface area is 300 m ² / g
-Dry silica 2: Dry silica, QS-102 manufactured by Tokuyama Corporation, nitrogen adsorption specific surface area is 200 m ² / g
-Dry silica 3: Dry silica, GS-90 manufactured by Tokuyama Corporation, nitrogen adsorption specific surface area is 90 m ² / g
-Wet silica 1: Wet silica, Zeosil 1165MP manufactured by Solay company, nitrogen adsorption specific surface area is 160 m ² / g
-Wet silica 2: Wet silica, Zeosil 200MP manufactured by Solvay, the nitrogen adsorption specific surface area is 210 m ² / g
-Coupling agent: Silane coupling agent, Si69 manufactured by Evonik
-Alkylsilane: Octyltriethoxysilane, Shin-Etsu Chemical KBE-3083
・ Processing aid: Nippon Seisaku Co., Ltd. diethylene glycol oil: Showa Shell Sekiyu Co., Ltd. Extract No. 4S

The types of raw materials used in Table 3 are shown below.
・ Carbon black, Toast carbon company's seast KH
・ Stearic acid: NOF beads stearic acid YR
・ Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Co., Ltd. ・ Anti-aging agent: Ozonon 6C manufactured by Seiko Chemical
・ Sulfur: Fine powder sulfur with Jinhua seal oil manufactured by Tsurumi Chemical Co., Ltd. ・ Vulcanization accelerator 1: Noxeller CZ-G manufactured by Ouchi Shinsei Chemical
・ Vulcanization accelerator 2: Sumokinol DG manufactured by Sumitomo Chemical Co., Ltd.

  As is clear from Table 2, it was confirmed that the rubber compositions for tires produced in Examples 1 to 8 had good mixing processability, and were excellent in reinforcement to rubber and low rolling resistance.

  As is clear from Table 1, the rubber composition of Comparative Example 1 was not subjected to the premixing step of the present invention, so the mixing processability was inferior, and the reinforcement to the rubber and the rolling resistance were deteriorated.

  Since the rubber composition of Comparative Example 2 did not contain a plasticizer component in the preliminary mixing step, the mixing processability was inferior, and the reinforcement to the rubber and the rolling resistance were deteriorated.

  Since the rubber composition of Comparative Example 3 did not contain oil, processing aid and alkylsilane in the pre-mixing step, the mixing processability was inferior and the meshing mixer deteriorated.

  Since the rubber composition of Comparative Example 4 did not contain a silane coupling agent in the premixing step, the mixing processability was inferior, and the silica reinforcing property and low rolling resistance of the diene rubber deteriorated.

  In the rubber composition of Comparative Example 5, the blending amount of dry silica exceeded 100 weight, so the mixing processability was inferior, and the reinforcement to the rubber and the rolling resistance deteriorated.

  In the rubber composition of Comparative Example 6, since the dry silica content is less than 5%, the reinforcement to rubber and the low rolling resistance cannot be improved.

  Since the rubber composition of Comparative Example 7 was mixed with wet silica instead of dry silica in the premixing step, the reinforcing property of silica against the diene rubber deteriorated.

Claims (5)

A method for producing a rubber composition for a tire comprising 5 to 100 parts by weight of dry silica and 100 parts by weight of a diene rubber, wherein the plasticizer component comprises a silane coupling agent, an oil, processing aid comprises at least one selected from alkyl silane, and characterized in that the after the plasticizer component and the dry silica were premixed in a mixer, wherein the diene rubber was poured into the mixer and mixed A method for producing a rubber composition for tires. The method for producing a tire rubber composition according to claim 1, wherein the dry silica has a nitrogen adsorption specific surface area of more than 160 m ² / g and 500 m ² / g or less.   The method for producing a rubber composition for a tire according to claim 1 or 2, wherein the plasticizer component is blended in an amount of 1 to 500% by weight based on the weight of the dry silica and premixed.   The said alkylsilane is alkyltriethoxysilane which has a C7-C20 alkyl group, The manufacturing method of the rubber composition for tires in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a rubber composition for a tire according to any one of claims 1 to 4, wherein wet silica is added and mixed together with the diene rubber.