JP6557087B2 - Steel cord topping rubber and tires - Google Patents

Description

  The present invention relates to steel cord topping rubbers—rubbers for coating steel cords—and tires.

Steel cords are used for tire belts and plies. The steel cord is made by twisting multiple steel wires. The steel cord adheres to the steel cord topping rubber by bonding Cu in the plating with S in the rubber to form copper sulfide (Cu _x S).

JP-A-2-233736

  A steel cord topping rubber excellent in adhesiveness with a steel cord after wet heat aging (hereinafter referred to as “wet heat adhesiveness”) is desired.

  In Patent Document 1, a steel cord is not used with a bead component-bead of polyoctenamer and sulfur vulcanized rubber of sulfur vulcanizable rubber. Describes a technique for obtaining a bundle of hard beads by using it. However, Patent Document 1 does not disclose the idea of improving the wet penetration of rubber by improving the penetration of rubber into the inside of the steel cord—the gap between the steel wires by blending polyoctenamer.

  This invention is made | formed in view of the said situation, The objective is to provide the steel cord topping rubber excellent in the penetration | invasion property to the inside of a steel cord, and excellent in wet heat adhesiveness.

  In order to solve the above problems, the present invention comprises the following arrangement. That is, the present invention relates to a steel cord topping rubber containing polyoctenylene. Polyoctenylene can improve the rubber flow when unvulcanized-the rubber penetration into the steel cord-and can prevent the steel cord from being corroded by water and scratching caused by rubbing between the steel cords. Since the copper sulfide and polyoctenylene formed at the initial stage of vulcanization are strongly entangled, the polyoctenylene can strengthen the entanglement with the copper sulfide and eliminate the gap for water to enter. Therefore, a steel cord topping rubber excellent in wet heat adhesion can be obtained by blending polyoctenylene.

  It is preferable to further blend a liquid butadiene rubber modified with maleic anhydride. The liquid butadiene rubber modified with maleic anhydride can trap residual amine compounds generated from the accelerator—reducing adhesion. Therefore, wet heat adhesiveness can be improved by blending maleic anhydride-modified liquid butadiene rubber.

  The present invention relates to a tire using a steel cord topping rubber for at least one of a rubber covering a steel cord of a belt and a rubber covering a steel cord of a ply.

  The steel cord topping rubber according to the embodiment of the present invention includes polyoctenylene. The weight average molecular weight of polyoctenylene is preferably 80,000 to 100,000. The melting point of polyoctenylene is preferably 65 ° C. or lower, more preferably 60 ° C. or lower. When the temperature is 60 ° C. or lower, the rubber flow during unvulcanization can be effectively improved. The glass transition temperature of polyoctenylene is preferably −75 to −50 ° C.

  The content of polyoctenylene is preferably 0.2 to 4 parts by mass with respect to 100 parts by mass of the diene rubber. There exists a possibility that the improvement effect of wet heat adhesiveness may not appear as it is less than 0.2 mass part. If the amount exceeds 4 parts by mass, the formation of copper sulfide may be hindered.

  The steel cord topping rubber according to the embodiment of the present invention may further include a maleic anhydride-modified liquid butadiene rubber (hereinafter referred to as “liquid butadiene rubber”). The liquid butadiene rubber preferably has fluidity at 23 ° C.

  The content of the liquid butadiene rubber is preferably 1 to 3 parts by mass with respect to 100 parts by mass of the diene rubber. There exists a possibility that the improvement effect of wet heat adhesiveness may not appear as it is less than 1 mass part. If the amount exceeds 3 parts by mass, the formation of copper sulfide may be hindered.

  The steel cord topping rubber according to the embodiment of the present invention may further include a diene rubber. Examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), and nitrile rubber (NBR). The diene rubber preferably has no fluidity at 23 ° C. The number average molecular weight of the diene rubber is preferably 100,000 or more.

  The steel cord topping rubber according to the embodiment of the present invention may further include sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and oil-treated sulfur. The sulfur content is preferably 2 to 8 parts by mass with respect to 100 parts by mass of the diene rubber. If it is less than 2 parts by mass, the crosslinking reaction or the reaction between rubber and brass plating may be insufficient. When it exceeds 8 parts by mass, a copper sulfide layer is excessively formed on the surface of the brass plating, and the wet heat adhesiveness and the heat resistant adhesiveness tend to be lowered.

  The steel cord topping rubber according to the embodiment of the present invention may further include a vulcanization accelerator. Sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization accelerator, dithiocarbamate vulcanization accelerator as vulcanization accelerator And so on. The content of the vulcanization accelerator is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

  The steel cord topping rubber according to the embodiment of the present invention may further include a methylene acceptor and a methylene donor. The hydroxyl group of the methylene acceptor and the methylene group of the methylene donor undergo a curing reaction, and adhesion to the steel cord is enhanced. From the viewpoint of compatibility with other components and the density and reliability of the resin after curing, resorcin or a resorcin derivative is preferred as the methylene acceptor, and a resorcin-alkylphenol co-condensed formalin resin is particularly preferred. The content of the methylene acceptor is preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the diene rubber. On the other hand, examples of the methylene donor include hexamethylenetetramine and melamine derivatives. As the melamine derivative, for example, methylol melamine, a partially etherified product of methylol melamine, a condensate of melamine, formaldehyde, and methanol is used. Of these, hexamethoxymethylmelamine is preferable. The methylene donor content is preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the diene rubber.

  The steel cord topping rubber according to the embodiment of the present invention may further include an organic acid metal salt. In addition to organic acid cobalt salts such as cobalt naphthenate, cobalt stearate, cobalt oleate, cobalt neodecanoate, cobalt rosinate, cobalt borate, cobalt maleate, etc., organic acid nickel salt, organic A molybdenum acid salt etc. can be mentioned. The content of the organic acid metal salt with respect to 100 parts by mass of the diene rubber is preferably 0.03 to 0.4 parts by mass, more preferably 0.1 to 0.3 parts by mass in terms of metal content.

  The steel cord topping rubber according to the embodiment of the present invention may further include a filler such as carbon black and silica as a reinforcing agent. For example, SAF, ISAF, HAF, FEF grade carbon black can be used. The carbon black content is preferably 5 to 100 parts by mass, and more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the diene rubber.

  The steel cord topping rubber according to the embodiment of the present invention may further include a compounding agent that is generally blended. Examples of such a compounding agent include a softening agent, zinc white, stearic acid, wax, anti-aging agent, and processing aid.

  The steel cord topping rubber according to the embodiment of the present invention can be produced by kneading with a mixer such as a Banbury mixer or a kneader.

  Steel cord topping rubbers according to embodiments of the present invention can be used to coat steel cords.

  A tire according to an embodiment of the present invention includes a belt. The belt includes a steel cord and a steel cord topping rubber that covers the steel cord. A tire according to an embodiment of the present invention includes a ply. The ply includes a steel cord and a steel cord topping rubber that covers the steel cord. The tire according to the embodiment of the present invention can be used as a pneumatic tire, and can be suitably used as a heavy duty tire—a tire for trucks, buses, construction vehicles, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Preparation of rubber composition]
A rubber composition was prepared by kneading with a Banbury mixer according to the formulation shown in Table 1. The detail of each component of Table 1 is as follows.
Carbon black (HAF): “Seast 300” manufactured by Tokai Carbon
・ Zinc flower: “Zinc flower 3” manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Stearic acid: “N-50” manufactured by NOF Corporation
Anti-aging agent: “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Resorcin-alkylphenol-formalin resin: “SUMIKANOL 620” manufactured by Sumitomo Chemical Co., Ltd.
・ Hexamethoxymethylmelamine: “CYRETS 963L” manufactured by Mitsui Cytec
・ Cobalt stearate: “Corebond CS-9.5” manufactured by Taikou Precision Chemical Co., Ltd.
Insoluble sulfur: “Muclon OT-20” manufactured by Shikoku Kasei Kogyo Co., Ltd.
DCBS: “Noxeller DZ-G” (N, N-dicyclohexyl-2-benzothiazolesulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Polyoctenylene: “VESTENAMER 8012” manufactured by EVONIK (polyoctenylene having a weight average molecular weight of 90000, a melting point of 54 ° C., and a glass transition temperature of −65 ° C.)
-Maleic anhydride modified liquid BR: "MA-75" manufactured by EVONIK

[Production of rubber and steel cord unvulcanized composite]
A rubber sheet having a thickness of 1.0 mm was produced by sheeting the rubber composition. Two pieces of steel cords with brass plating (structure: 3 x 0.20 mm + 6 x 0.35 mm) arranged at 12/25 mm intervals and sandwiched between rubber sheets are stacked, and there is no steel cord with two steel cords A sulfur composite was prepared.

[Evaluation-Adhesiveness after wet heat aging]
A test piece was obtained by vulcanizing the unvulcanized composite at 150 ° C. for 30 minutes. After leaving the test piece in saturated steam at 105 ° C. for 96 hours, a peeling test between two layers of steel cords was performed using an autograph (DCS500 manufactured by Shimadzu Corporation), and rubber adhesion of the steel cords was visually confirmed. The adhesion was evaluated using the rubber adhesion rate as an index. The comparative example 1 was set to 100, and the adhesiveness of each example was indicated by an index. A larger value means better adhesion. When the numerical value was 10 or more larger than Comparative Example 1, it was determined that there was an improvement effect.

  Compared with Comparative Example 1, Examples 1 to 4—Examples in which polyoctenylene was blended—had good adhesiveness. The improvement effect of Example 4—an example in which polyoctenylene and maleic anhydride-modified liquid BR were blended—was greater than the sum of the improvement effect of Example 1 and the improvement effect of Comparative Example 2.

Claims (5)

With polyoctenylene,
Liquid butadiene rubber modified with maleic anhydride;
Diene rubber,
Sulfur and
Including a vulcanization accelerator,
Steel cord topping rubber used for tires .   The steel cord topping rubber according to claim 1, wherein a content of the polyoctenylene is 0.2 to 4 parts by mass with respect to 100 parts by mass of the diene rubber.   The steel cord topping rubber according to claim 1 or 2, wherein a content of the maleic anhydride-modified liquid butadiene rubber is 1 to 3 parts by mass with respect to 100 parts by mass of the diene rubber.   The steel cord topping rubber according to any one of claims 1 to 3, wherein the vulcanization accelerator includes a sulfenamide vulcanization accelerator.   A tire using the steel cord topping rubber according to any one of claims 1 to 4 in at least one of rubber covering a steel cord of a belt and rubber covering a steel cord of a ply.