JP5606940B2 - Method for producing rubber composition - Google Patents

Description

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

  In recent years, there has been an increasing demand for lower fuel consumption in automobiles, and there is a strong demand for lower fuel consumption in tires. It is known that the rolling resistance of a tire is related to the heat buildup of the rubber composition. For this reason, various studies have been made to reduce the hysteresis loss of the rubber composition, that is, to suppress the loss factor (tan δ), thereby suppressing the heat generation and improving the fuel efficiency of the tire.

  In order to meet such demands, it is known that a diene-based synthetic rubber such as styrene butadiene rubber is added with a modifying group during production of the polymer to produce a terminal-modified polymer. Since the terminal-modified diene rubber has better compatibility with a reinforcing filler such as carbon black than the unmodified diene rubber, heat generation can be suppressed and fuel efficiency can be improved. However, since this method can only be carried out under anionic polymerization, it is required to improve the low heat build-up by a simpler method.

  The present inventor has found that certain dicarboxylic acid compounds contribute to the deagglomeration of carbon and contribute to low heat build-up by improving the dispersibility of carbon black, and based on this finding, the present invention has been completed.

  In this regard, Patent Document 1 describes that polysulfide dicarboxylic acid is used as a coupling agent when silica is blended in a tire containing a diene rubber.

  Patent Document 2 describes the use of an alkylamine salt of a carboxylic acid group-containing disulfide as a vulcanization accelerator in a diene rubber composition.

  Furthermore, in Patent Document 3, disulfide is compounded with disulfide compound having amino group, carboxyl group, etc. in diene rubber, premixed without compounding carbon black, and then blended with carbon black. A method for producing a rubber composition is described.

  However, none of the documents describes the use of a dicarboxylic acid compound for improving the dispersibility of carbon black. Moreover, in the cited document 3, when carbon black is mix | blended at a 1st mixing process, diene type rubber | gum and carbon black will couple | bond together via a disulfide, and it describes that workability and a dispersibility fall. Paragraph [0024]).

JP-A-7-17205 Japanese Patent No. 4156022 JP 2010-18715 A

  The present invention has been made in view of the above, and a method for producing a rubber composition capable of improving the heat buildup of a tire obtained by improving the dispersibility of carbon black and thus improving the fuel efficiency. I will provide a.

In order to solve the above problems, the method for producing a rubber composition of the present invention contains a rubber component made of a diene rubber and carbon black, and the silica content is 5.0 mass based on the carbon black. der than% is, and a method for producing a rubber composition containing no calcium carbonate, with respect to 100 parts by mass of the rubber component, 0.1 mass% of carbon black 25 parts by mass or more and a carbon black as a reference larger, it viewed including the step of mixing by blending a dicarboxylic acid compound represented by the ratio of the following equation is not more than 2.0 mass% (1), producing a tread rubber or the rubber composition for a side wall of the tire Shall be.

_{HOOC- (CH 2) n -S x} - (CH 2) m -COOH ... (1)
However, in Formula (1), n shows the number of 1-6, m shows the number of 0-6, x shows the number of 0-6.

  According to the production method of the present invention, the dicarboxylic acid represented by the formula (1) assists the deagglomeration of carbon in the rubber composition and improves the dispersibility, thereby producing a tire with improved fuel efficiency. It becomes possible to do.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  In the manufacturing method of this invention, 25 mass parts or more of carbon black is mix | blended with respect to 100 mass parts of rubber components, Preferably it mix | blends in 30-150 mass parts. If the blending amount of the carbon black is less than 25 parts by mass, it is difficult to obtain the reinforcing effect expected by blending. On the other hand, if it exceeds 150 parts by mass, the workability and elongation at break may be deteriorated.

  In the production method of the present invention, in order to obtain the deagglomeration effect of the carbon black, a dicarboxylic acid compound represented by the following formula (1) is blended and mixed in the same step as the blending step of carbon black.

_{HOOC- (CH 2) n -S x} - (CH 2) m -COOH ... (1)
However, in Formula (1), n shows the number of 1-6, m shows the number of 0-6, x shows the number of 0-6.

  The dicarboxylic acid compound blended and mixed in the same process as carbon black contributes to the deagglomeration of carbon by entering the gaps between the carbon aggregates, and as a result, the dispersibility of the carbon black is improved and the low heat build-up is improved. As a result, it is considered that the fuel efficiency of the tire is improved.

  Specific examples of the dicarboxylic acid compound represented by the above formula (1) include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, dithiodipropionic acid, thiodipropionic acid and the like. These dicarboxylic acid compounds can use what is marketed, and can also be manufactured by a well-known method.

  The blending amount of the dicarboxylic acid compound is preferably greater than 0.1% by mass and less than 5.0% by mass, more preferably 2.0% by mass or less, based on carbon black. If it is less than 0.1% by mass, it is difficult to obtain a desired deagglomerating effect of carbon black, that is, an effect of reducing fuel consumption. On the other hand, if it exceeds 2.0% by mass, the effect of reducing fuel consumption will not be reduced, but it becomes difficult to obtain an effect proportional to the increase in the amount of blending, and this is disadvantageous in terms of cost. Is preferably used.

  In the method for producing a rubber composition according to the present invention, a composition and steps according to a conventional method for producing a diene rubber composition for tires are adopted except that the dicarboxylic acid compound is blended in the same step as that of carbon black. be able to.

  Examples of the diene rubber that can be used in the present invention include various natural rubbers (NR), various polyisoprene rubbers (IR), various styrene butadiene rubbers (SBR), various polybutadiene rubbers (BR), etc. One kind may be used, or two or more kinds may be used in combination. Preferably, natural rubber and / or isoprene rubber is used.

  In the production method of the present invention, silica is not used or, if used, less than 5.0% by mass with respect to carbon black. This is because when the blending amount is 5.0% by mass or more, the dicarboxylic acid reacts with silica, and it is difficult to obtain the intended deaggregation effect of the carbon black. When silica is used, examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like.

  The rubber composition according to the present invention is generally used in tire rubber compositions such as zinc white, stearic acid, anti-aging agent, wax, vulcanizing agent, and vulcanization accelerator in addition to the above components. Various additives can be blended. Examples of the vulcanizing agent include sulfur and sulfur-containing compounds, and are not particularly limited. However, the blending amount is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is 0.5-5 mass parts. Moreover, as a compounding quantity of a vulcanization accelerator, it is preferable that it is 0.1-7 mass parts with respect to 100 mass parts of said rubber components, More preferably, it is 0.5-5 mass parts. The rubber composition is prepared by kneading according to a conventional method using a rubber kneader such as a normal Banbury mixer or kneader.

  The rubber composition obtained by the above production method can be used as a tread rubber or a side wall rubber of a tire, and the rubber composition is vulcanized and molded at, for example, 140 to 180 ° C. according to a conventional method. Can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Using a Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, in the first mixing stage, components other than sulfur and vulcanization accelerator are added and mixed, and then the resulting mixture is finally mixed. A rubber composition for a tire was prepared by adding and mixing sulfur and a vulcanization accelerator in the stage. The details of each formulation in Table 1 are as follows.

・ NR: Natural rubber (RSS # 3)
・ Carbon black: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
・ Zinc flower: "Zinc flower 3" manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Stearic acid: “Lunac S20” manufactured by Kao Corporation
・ Sulfur: “5% oil-treated powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
・ Vulcanization accelerator: “Noxeller NS-G” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Dithiopropionic acid: manufactured by SC Organic Chemical Co., Ltd. ・ Thiodipropionic acid: manufactured by SC Organic Chemical Co., Ltd. ・ Adipic acid: manufactured by Nacalai Tesque Co., Ltd. 45% aqueous solution)

  About each obtained rubber composition, MH and loss factor tan-delta were measured using the test piece of the predetermined shape vulcanized at 150 degreeC for 30 minutes. Each measuring method is as follows.

MH: The maximum torque when vulcanized at 150 ° C. for 45 minutes is indicated by an index with the value of Comparative Example 1 as 100. The larger the value, the higher the degree of vulcanization.

Loss coefficient tan δ: Based on JIS K6394, using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd., measuring the loss coefficient tan δ at a frequency of 10 Hz, a static strain of 10%, a dynamic strain of 2%, and a temperature of 70 ° C. The value is shown as an index with the value of Comparative Example 1 being 100. It shows that it is excellent in low exothermic property, so that a numerical value is small.

  As can be seen from the results shown in Table 1, the rubber compositions obtained in Examples 1 to 6 according to the present invention have significantly improved fuel efficiency without substantially increasing the degree of vulcanization. It was recognized that This indicates that the blended dicarboxylic acid compound did not act as a vulcanization accelerator and contributed to the improvement of carbon dispersibility. On the other hand, in Comparative Example 2 in which the amount of the dicarboxylic acid compound is small, the effect of reducing fuel consumption was not substantially obtained. Moreover, in Comparative Example 3 using diammonium dithiodiglycolate, a certain level of fuel economy was obtained, but the degree of vulcanization increased greatly and the dicarboxylic acid compound acted as a vulcanization accelerator. I understand.

  The composition obtained by the production method of the present invention can be used for various tires such as passenger cars, light trucks, trucks and buses.

Claims (1)

Containing a rubber component and carbon black consisting of a diene rubber, a method of manufacturing the silica content of the Ri less than 5.0% by mass of carbon black as a reference, and a rubber composition containing no calcium carbonate And
Represented by the following formula (1) with respect to 100 parts by mass of the rubber component , a ratio of 25 parts by mass or more of carbon black and a ratio of 0.1% by mass or more and 2.0% by mass or less based on the carbon black. look including the step of mixing by blending a dicarboxylic acid compound,
A method for producing a rubber composition, comprising producing a tread rubber for a tire or a rubber composition for a sidewall .
_{HOOC- (CH 2) n -S x} - (CH 2) m -COOH ... (1)
However, in Formula (1), n shows the number of 1-6, m shows the number of 0-6, x shows the number of 0-6.