JP2020075984A - Rubber composition for tire side wall - Google Patents

Abstract

To provide a rubber composition for a tire side wall, to be served as a raw material of a pneumatic tire with improved fatigue resistance performance while reducing an odor characteristic of rubber.SOLUTION: A rubber composition for a tire side wall includes 1.0-10 pts.mass of composite powder containing a persimmon extract and a sodium carbonate based on 100 pts.mass of a total amount of a rubber constituent. In the composite powder, a mass ratio of the persimmon extract and the sodium carbonate is preferably 1:1-5:1. An amount of an active ingredient of the persimmon extract in the composite powder is preferably 0.01-8.0 pts.mass based on 100 pts.mass of the total amount of the rubber constituent.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a rubber composition for tire sidewalls, and more particularly to a rubber composition that is a raw material for a pneumatic tire that has little odor peculiar to rubber and is excellent in fatigue resistance.

  In general, tires are used in various traveling environments, and particularly, sidewall members are repeatedly subjected to vibration under a load applied during traveling, and therefore are required to have excellent fatigue resistance. The rubber member which occupies most of the side wall member generally has a peculiar odor, and reduction of the odor peculiar to rubber is required in the market.

  Patent Document 1 below describes a method for producing a natural rubber-white filler composite including a step of mixing a natural rubber latex and a white filler, subjecting the obtained mixture to a purification treatment, and then coagulating and drying the mixture. Has been done.

  Further, in Patent Document 2 below, a rubber composition for a tire is described in which 5 to 130 parts by weight of an inorganic filler and 0.01 to 10 parts by weight of a tea extract containing catechin are mixed with 100 parts by weight of a diene rubber. Has been done.

  In addition, Patent Document 3 below describes a method for producing a rubber wet masterbatch, which includes a step of adding tannin to a rubber latex solution containing a filler, solidifying and then drying.

  Furthermore, in Patent Document 4 below, after adding water to the persimmon juice and stirring it to obtain a mixed solution, an aqueous sodium carbonate solution is added to adjust the pH value to 8.5 to 9.0. And a method for producing a deodorant against a sulfur-based malodor.

JP, 2018-35250, A JP, 2010-31260, A JP 2012-207088A Japanese Patent No. 3919729

  However, as a result of diligent study by the present inventor, it is difficult to provide a pneumatic tire having improved fatigue resistance while reducing the odor peculiar to rubber with the techniques described in Patent Documents 1 to 3 above. It has been found. In addition, the said patent document 4 describes the technology regarding a deodorant, it does not have any problem about the odor peculiar to a pneumatic tire (rubber), let alone the improvement of various performances of a pneumatic tire. There is no suggestion.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce the odor peculiar to rubber, and to provide a rubber composition for a tire sidewall, which is a raw material for a pneumatic tire having improved fatigue resistance. To provide.

  The above problem can be solved by the following configuration. That is, the present invention relates to a rubber composition for a tire sidewall, which contains 1.0 to 10 parts by mass of a composite powder containing a persimmon extract and sodium carbonate when the total amount of the rubber component is 100 parts by mass. .

Since the rubber composition according to the present invention contains a composite powder containing a persimmon extract and sodium carbonate, when the final pneumatic tire is obtained, (1) reduction of odor peculiar to rubber and (2) resistance to It is possible to achieve both improvement in fatigue performance. The reason why these effects are obtained is not clear, but can be estimated as follows, for example.
(1) At least the condensed tannin contained in the persimmon extract is partially oxidized by complexing at least the persimmon extract and sodium carbonate and pulverizing, and the reduction originally possessed by the condensed tannin in the molecule. In addition to the ability, an oxidizing ability can be added. This makes it possible to exert a deodorizing effect on both the components deodorized by the oxidation reaction and the components deodorized by the reduction reaction. Therefore, the odor peculiar to rubber can be reduced by chemically reacting the partially oxidized condensed tannin with the odor components such as nitrogen compounds, sulfur compounds and lower fatty acids contained in the rubber.
(2) The condensed tannin contained in the extract of persimmon has a large number of phenolic hydroxyl groups in the molecule, which complements the radicals generated in rubber that is repeatedly vibrated under a load. To do. As a result, it is possible to suppress deterioration of the rubber member of the sidewall and improve fatigue resistance.

  In the present invention, when the total amount of the rubber component is 100 parts by mass, the compounded amount of the composite powder is set to 1.0 to 10 parts by mass to reduce the odor peculiar to rubber and improve fatigue resistance. Can be compatible with both. In particular, the vulcanization rate of the rubber composition can be further stabilized by setting the blending amount to 10 parts by mass or less.

  In the above rubber composition for tire sidewall, it is preferable that a mass ratio of the persimmon extract and the sodium carbonate in the composite powder is 1: 1 to 5: 1. Further, in the above rubber composition for tire sidewall, when the total amount of the rubber component is 100 parts by mass, the amount of the active ingredient of the persimmon extract in the composite powder is 0.01 to 8.0 parts by mass. preferable. According to this structure, the odor peculiar to rubber can be further reduced, which is preferable.

  The rubber composition for a tire sidewall according to the present invention contains a rubber component and a composite powder containing a persimmon extract and sodium carbonate as at least essential components.

  The rubber composition for a tire sidewall according to the present invention preferably contains a diene rubber as a rubber component. Examples of the diene rubber include natural rubber (NR), polyisoprene rubber (IR), polybutadiene (BR), polystyrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR) and the like.

  The composite powder contains at least a persimmon extract and sodium carbonate as essential components. The persimmon extract contains condensed tannin which is a kind of polyphenol, and this condensed tannin has many phenolic hydroxyl groups (-OH groups), which are chemically bonded to various malodorous components contained in rubber. , Deodorizing effect. In particular, the condensed tannin is complexed with sodium carbonate and partially oxidized, so that the odor peculiar to rubber can be reduced at a high level. The composite powder contains persimmon extract and sodium carbonate as essential components, and may contain a water-soluble polymer such as trehalose or cellulose.

In order to achieve a good balance between the reduction of odor peculiar to rubber and the improvement of fatigue resistance, the compounding amount of the composite powder should be 1.0 to 10 parts by mass when the total amount of rubber components is 100 parts by mass. Is preferable, and it is more preferable to set it as 3.0-8.0 mass parts.

  In order to achieve a good balance between the reduction of odor peculiar to rubber and the improvement of fatigue resistance, the mass ratio of persimmon extract and sodium carbonate in the composite powder is 1: 1 to 5: 1. It is preferably 2: 1 to 4: 1 and more preferably. Further, in the rubber composition for a pneumatic tire, when the total amount of the rubber component is 100 parts by mass, the amount of the active ingredient of the persimmon extract in the composite powder is preferably 0.01 to 8.0 parts by mass, It is more preferably 0.3 to 5.0 parts by mass. The content of sodium carbonate in the composite powder is not particularly limited as long as it satisfies both the amount of the active ingredient of the persimmon extract in the composite powder and the mass ratio of the persimmon extract and sodium carbonate.

  The rubber composition for a tire sidewall according to the present invention can be compounded with a compounding agent known to those skilled in the art as a component other than the rubber component, and the composite powder containing the persimmon extract and sodium carbonate, such as carbon black, Silica, a silane coupling agent, a vulcanizing compounding agent, an antioxidant, a zinc oxide, stearic acid, a softening agent such as wax and oil, a processing aid, and the like can be added.

  As the carbon black, for example, conductive carbon black such as acetylene black or Ketjen black can be used in addition to carbon black used in a usual rubber industry such as SAF, ISAF, HAF, FEF and GPF. The rubber composition for a pneumatic tire according to the present invention preferably contains 10 to 120 parts by mass of carbon black, and more preferably 20 to 100 parts by mass, based on 100 parts by mass of the diene rubber.

  As silica, there are used wet silica, dry silica, sol-gel silica, surface-treated silica and the like which are commonly used for rubber reinforcement. Of these, wet silica is preferable.

  The silane coupling agent is not particularly limited as long as it contains sulfur in the molecule, and various silane coupling agents blended with silica in the rubber composition can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide (for example, "Si69" manufactured by Degussa), bis (3-triethoxysilylpropyl) disulfide (for example, "Si75" manufactured by Degussa), bis (2-tri Sulfidosilanes such as ethoxysilylethyl) tetrasulfide, bis (4-triethyloxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltrisulfide Mercaptosilanes such as methoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, and mercaptoethyltriethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, 3-propionylthiopropyltriethoxysilane. Included are protected mercaptosilanes such as methoxysilane.

  As the anti-aging agent, usually used for rubber, aromatic amine anti-aging agent, amine-ketone anti-aging agent, monophenol anti-aging agent, bisphenol anti-aging agent, polyphenol anti-aging agent, dithiocarbamic acid Antiaging agents such as salt antiaging agents and thiourea antiaging agents may be used alone or in admixture.

  Examples of the vulcanizing compounding agent include vulcanizing agents such as sulfur and organic peroxides, vulcanization accelerators, vulcanization accelerating aids, vulcanization retarders and the like.

  Sulfur as a vulcanizing compounding agent may be ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used.

  As the vulcanization accelerator, usually used for rubber vulcanization, sulfenamide-based vulcanization accelerator, thiuram-based vulcanization accelerator, thiazole-based vulcanization accelerator, thiourea-based vulcanization accelerator, guanidine-based vulcanization A vulcanization accelerator such as an accelerator or a dithiocarbamate vulcanization accelerator may be used alone or in an appropriate mixture.

  The rubber composition according to the present invention, a rubber component, and a composite powder containing a persimmon extract and sodium carbonate, further carbon black, silica, a silane coupling agent, a vulcanizing compounding agent, an antioxidant, zinc oxide, It can be obtained by kneading stearic acid, wax, a softening agent such as oil, a processing aid, and the like using a kneader such as a Banbury mixer, a kneader, or a roll used in a usual rubber industry.

  In addition, the mixing method of each of the above components is not particularly limited, and a sulfur-based vulcanizing agent, and a compounding component other than a vulcanizing compounding agent such as a vulcanization accelerator are kneaded in advance to form a masterbatch, and the remaining components are added. And further kneading, a method of adding each component in an arbitrary order and kneading, a method of simultaneously adding all components and kneading, and the like.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described. As for the evaluation items in the examples and the like, the rubber samples obtained by heating and vulcanizing each rubber composition at 160 ° C. for 30 minutes were evaluated based on the following evaluation conditions.

(1) Odor evaluation of rubber Odor was sensory evaluated according to JIS Z9080. A six-level evaluation was performed. The higher the value, the more strongly the odor is felt, which means that the odor cannot be reduced.

(2) Fatigue resistance performance According to JIS K6260, the measurement was performed under the condition of 23 ° C., the number of times until the crack growth reached 2 mm was determined, and the value was set as an index with the value of Comparative Example 1 as 100. The larger the index, the better the fatigue resistance.

(Preparation of rubber composition)
According to the formulation of Table 1, the rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 5 were blended and kneaded with a usual Banbury mixer to prepare rubber compositions. Each compounding agent shown in Table 1 is shown below (in Table 1, the compounding amount of each compounding agent is shown by the number of parts by mass relative to 100 parts by mass of the rubber component).
a) Natural rubber (NR): "RSS # 3"
b) Butadiene rubber (BR): "BR150B" manufactured by Ube Industries c) Carbon black: "Seast SO" manufactured by Tokai Carbon d) Stearic acid: "Bead stearic acid" manufactured by NOF Corporation e) Zinc oxide: "Zinc oxide" 2 types "Mitsui Mining & Smelting Company f) Inorganic filler (A) (white filler):" Nobelite TT "Nitto Koka Kogyo g) Inorganic filler (B) (sodium carbonate):" Sodium carbonate "Fuji Film Wako Pure Chemical Industries, Ltd. h) Condensed tannin: “Condensed tannin” Kawamura Tsusho i) Composite powder containing persimmon extract and sodium carbonate: “Pancil PS-M” Release Kagaku Kogyo j) Anti-aging Agent: "Nocrac 6C" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. k) Sulfur: "Powdered Sulfur" manufactured by Tsurumi Chemical Co., Ltd. l) Vulcanization accelerator: "Sokushiru CZ" manufactured by Sumitomo Chemical Co., Ltd.

  From the results of Table 1, the vulcanized rubbers of the rubber compositions according to Examples 1 to 3 have a reduced odor compared with the vulcanized rubbers of the rubber compositions according to Comparative Example 1, and have fatigue resistance performance. It turns out to be excellent.

Claims (3)

  A rubber composition for a tire sidewall, containing 1.0 to 10 parts by mass of a composite powder containing a persimmon extract and sodium carbonate when the total amount of the rubber component is 100 parts by mass.   The rubber composition for a tire sidewall according to claim 1, wherein a mass ratio of the persimmon extract and the sodium carbonate in the composite powder is 1: 1 to 5: 1. The rubber composition for a tire sidewall according to claim 1 or 2, wherein the total amount of the rubber component is 100 parts by mass, and the amount of the effective component of the persimmon extract in the composite powder is 0.01 to 8.0 parts by mass. object.