JP2005255785A - Rubber composition for coating steel cord and steel cord / rubber composite using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for coating a steel cord, improved with fatigue resistance, aiming at a light weight and improving initial bonding performance to the steel cord and deterioration resistant bonding property, and a steel cord/rubber composite material consisting of the rubber composition and the steel cord. <P>SOLUTION: This rubber composition for coating the steel cord is provided by blending collagen particles having ≤20 μm mean particle diameter. For example, 3-30 pts. wt. collagen particles having ≤20 μm mean particle diameter are blended with 100 pts. wt. natural rubber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber composition for coating a steel cord and a steel cord / rubber composite using the same. More specifically, a rubber composition having improved fatigue resistance, low heat build-up, initial adhesion performance to steel cord and resistance to deterioration, and a steel cord / rubber composite comprising the rubber composition and the steel cord About the body.

  In general, a steel cord is used as a reinforcing material because a large load is applied to an automobile tire or a rubber conveyor belt. Particularly in the case of automobile tires, if the steel cord and rubber are peeled off due to the heat generated by the tire during running, it may cause a fatal tire failure. Therefore, it is desired to further improve the adhesion between the steel cord and rubber.

  Conventionally, as a means of improving the adhesion and reinforcement between steel cord and rubber, a method of plating brass on the steel cord, or a method of blending a rubber coating the steel cord with a cobalt salt of an organic acid as an adhesion promoter It has been known. However, although these methods are excellent in the adhesiveness immediately after vulcanization, that is, the initial adhesive performance, there is a problem that the thermal deterioration of the rubber and the generation of water thereby are promoted and the deterioration-resistant adhesiveness is poor.

  Further, in recent years, a method has been proposed in which a hygroscopic porous inorganic filler such as clay is added to the coating rubber to improve the initial adhesion performance with steel cord and the deterioration-resistant adhesion (see Patent Document 1). ). However, this method improves initial adhesion performance and anti-degradation adhesion, but has a problem in that the fatigue resistance of the rubber is lowered, and heat is increased due to an increase in the weight of the rubber.

JP 2000-7838 A

  An object of the present invention is to improve the fatigue resistance, reduce the weight, and improve the initial adhesion performance and deterioration-resistant adhesion to the steel cord, and the rubber composition for steel cord coating, and the rubber composition and the steel. The object is to provide a steel cord / rubber composite comprising a cord.

  The present invention relates to a rubber composition for steel cord coating comprising a rubber component and collagen particles having an average particle size of 20 μm or less.

  The rubber composition preferably contains 3 to 30 parts by weight of collagen particles having an average particle diameter of 20 μm or less with respect to 100 parts by weight of the rubber component.

  The rubber composition preferably further contains a cobalt salt of an organic acid.

  The present invention also relates to a steel cord / rubber composite comprising the rubber composition and a steel cord.

  According to the present invention, as a rubber composition for steel cord coating, by adding collagen particles to the rubber component, the fatigue resistance is improved, the weight is reduced, and the initial adhesion performance and the degradation-resistant adhesion to the steel cord are achieved. Can be improved.

  The rubber composition for steel coating of the present invention comprises a rubber component and collagen particles.

  As the rubber component used in the present invention, natural rubber or synthetic rubber is used. Examples of the synthetic rubber include diene synthetic rubbers such as butadiene rubber (BR), isoprene rubber (IR), and styrene butadiene rubber (SBR), butyl rubber, halogenated butyl rubber (for example, brominated butyl rubber), and paramethylstyrene group. Examples thereof include butyl rubber such as butyl rubber (for example, a copolymer of isobutylene and p-halogenated methylstyrene), ethylene propylene diene rubber (EPDM), and the like. These rubber components can be used alone or in admixture of two or more.

  Among the rubber components, natural rubber is preferably used particularly from the viewpoint of breaking strength, and it is preferable that the rubber component contains natural rubber in an amount of 50% by weight or more, further 60% by weight or more. If the content of natural rubber is less than 50% by weight, the fracture strength tends to decrease.

  The rubber composition of the present invention contains collagen particles. Collagen particles contain moisture due to their hygroscopic properties, so when added to rubber, moisture is released during vulcanization, effectively acting to form an adhesive layer with the steel cord, and improving the initial adhesion to the steel cord. Improve. In addition, since the collagen particles from which moisture has been released absorbs moisture generated with rubber deterioration, the destruction of the adhesive layer by moisture is suppressed, and the deterioration-resistant adhesion is improved. Moreover, since the specific gravity of collagen particles is smaller than that of a porous inorganic filler or the like, it leads to weight reduction of the rubber composition.

  As said collagen particle, the composite_body | complex (refer Unexamined-Japanese-Patent No. 2002-30300) which consists of collagen and a resin component can be used, for example. In such a composite, the collagen fiber bundle is formed by stitching the side surfaces of the collagen coarse fiber with a resin component formed by non-catalytic graft copolymerization, and the collagen fiber bundle is dried and then pulverized. Can be obtained. Since such a composite can be uniformly dispersed in the rubber composition, it can be blended in the rubber composition to provide flexibility and rigidity derived from the properties of the collagen fiber bundle, as well as durability and heat resistance. Can be granted.

  The average particle diameter of the collagen particles is 20 μm or less, preferably 16 μm or less. By blending collagen particles having an average particle size of 20 μm or less, the fatigue resistance of rubber is improved. If the average particle diameter exceeds 20 μm, collagen particles in the rubber composition are likely to be the starting point of the breaking phenomenon, and the reinforcing property of the rubber is lowered. When the thickness is 20 μm or less, the reinforcing property is improved. The average particle diameter of the collagen particles is preferably 5 μm or more, more preferably 8 μm or more. When the average particle diameter is less than 5 μm, the reinforcing effect of the reinforcing property tends to be lowered.

  The rubber composition of the present invention preferably contains 3 parts by weight or more, more preferably 8 parts by weight or more, and more preferably 10 parts by weight or more with respect to 100 parts by weight of the rubber component. preferable. When the content is less than 3 parts by weight, the effect of improving the initial adhesiveness and deterioration-resistant adhesiveness of rubber tends to be insufficient. The rubber composition preferably contains 30 parts by weight or less of the collagen particles, more preferably 25 parts by weight or less, and even more preferably 20 parts by weight or less. When it exceeds 30 parts by weight, the strength of the rubber tends to decrease.

  Furthermore, various adhesion promoters conventionally used in steel cord coating rubber compositions can be blended with the rubber composition of the present invention. Examples of such an adhesion promoter include metal salts of organic acids, particularly cobalt salts of organic acids.

  The organic acid constituting the metal salt of the organic acid may be saturated, unsaturated, linear or branched, for example, neodecanoic acid, stearic acid, naphthenic acid, rosin acid, tall oil acid Oleic acid, linoleic acid, linolenic acid and the like. Further, when the metal is multivalent, a part of these organic acids can be replaced with a compound containing boron, boric acid, aluminum or the like.

  The compounding amount of the organic acid metal salt is preferably 0.1 parts by weight or more in terms of the metal element content with respect to 100 parts by weight of the rubber component. Moreover, it is preferable that the compounding quantity of a metal salt is 0.2 weight part or less.

  The rubber composition of the present invention can further contain sulfur. As sulfur, insoluble sulfur is preferable in terms of excellent processability in the production process of the rubber composition. When insoluble sulfur is used, it is preferably 60 to 90% insoluble in rubber as a medium. If it is less than 60%, the processability on the process due to the Bloom phenomenon tends to be lowered.

  The compounding amount of sulfur is preferably 3 parts by weight or more, and more preferably 4 parts by weight or more with respect to 100 parts by weight of the rubber component. If the amount of sulfur is less than 3 parts by weight, the adhesive strength tends to be insufficient. Moreover, it is preferable that the compounding quantity of sulfur is 8 weight part or less, Furthermore, it is preferable that it is 7 weight part or less. When the amount of sulfur exceeds 8 parts by weight, the adhesive strength is lowered, and the heat aging resistance as a physical property of rubber tends to be lowered.

  The rubber composition of the present invention can further contain carbon black. As carbon black, N329, N330, N220, N219, etc. are used, for example.

  Furthermore, in the rubber composition of the present invention, in addition to the rubber component, collagen particles, metal salt, sulfur, and carbon black, a compounding agent that is usually used in the rubber industry is within a range that does not impair the effects of the present invention. It can mix | blend suitably. Specifically, fillers other than carbon black such as silica, softeners such as aroma oil, guanidine compounds such as diphenylguanidine, thiazole compounds such as mercaptobenzothiazole, N, N′-dicyclohexyl-2-benzothiazolylsulfur Vulcanization accelerators such as sulfenamide compounds such as phenamide, thiuram compounds such as tetramethylthiuram disulfide, vulcanization accelerators such as zinc oxide, poly (2,2,4-trimethyl-1,2-dihydroquinoline ), And anti-aging agents such as amine compounds such as phenyl-α-naphthylamine.

  The steel cord / rubber composite of the present invention comprises the rubber composition and a steel cord, and is obtained by coating the surface of the steel cord with the rubber composition.

  The steel cord is preferably plated with brass, zinc, or an alloy of these with nickel or cobalt in order to improve the adhesion layer with rubber, particularly those with brass plating. preferable. When the Cu content in the brass plating is 75% by weight or less, preferably 55 to 70% by weight, good and stable adhesiveness can be obtained. In addition, there is no restriction | limiting in particular about the twist structure of a steel cord.

  The steel cord / rubber composite of the present invention can be used for rubber products such as automobile tires and conveyor belts to obtain an excellent reinforcing effect.

  Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

Example 1 and Comparative Examples 1-3
Below, the various chemical | medical agents used in the Example and the comparative example are demonstrated.
Natural rubber: RSS # 3
Carbon black: N329 manufactured by Mitsubishi Chemical Corporation
Clay: Union clay collagen particles manufactured by Takehara Chemical Co., Ltd. 1: Ergona P-100X manufactured by Matsuoka Chemical Co., Ltd. (average particle size: 8 μm)
Collagen particles 2: Collagen particles having an average particle diameter of 100 μm Zinc oxide: Zinc flower No. 1 cobalt stearate manufactured by Mitsui Mining & Smelting Co., Ltd .: COST manufactured by Dainippon Ink & Chemicals, Inc.
Anti-aging agent: NOCRACK 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.
90% insoluble sulfur: Sanfel EX manufactured by Sanshin Chemical Industry Co., Ltd.
Vulcanization accelerator: Noxeller DZ made by Ouchi Shinsei Chemical Co., Ltd.

  The contents shown in Table 1 except for 90% insoluble sulfur and vulcanization accelerator were kneaded at 120 to 150 ° C. for 7 minutes. Furthermore, 90% insoluble sulfur and a vulcanization accelerator were added and kneaded at 100 ° C. for 2 minutes to obtain a rubber composition.

The following test was implemented about the obtained rubber composition.
(Initial adhesion performance)
Steel cords (1 × 5 structure, strand diameter 0.25 mm) plated with brass (Cu: 63 wt%, Zn: 37 wt%) are arranged in parallel at intervals of 12.5 mm, and both surfaces are made of each rubber composition. Coated with sheet. Further, vulcanization was performed at 160 ° C. for 20 minutes to prepare a sample having a thickness of 12.5 mm. In accordance with ASTM-D-2229, the pulling force when the steel cord was pulled out of the sample was measured, and the value of Comparative Example 1 was taken as 100 and displayed as an index. The larger the numerical value, the better the initial adhesiveness.

(Degradation resistance)
A sample was prepared by the same method as in the case of initial adhesiveness, and this was left to deteriorate in air at 100 ° C. for 7 days, and then the pulling force was measured by the same method. The value of Comparative Example 1 was taken as 100 and displayed as an index. The larger the value, the better the degradation resistance.

(Fatigue resistance)
Each rubber composition was vulcanized at 150 ° C. for 30 minutes to prepare a measurement sample having a width of 25 mm × a length of 150 mm × a thickness of 6 mm. With respect to the measurement sample, the number of times until the sample broke at a room temperature of 25 ° C. was measured by a dematcher test method, and the value of Comparative Example 1 was set to 100 and displayed as an index. The larger the value, the better the fatigue resistance.

(Lightweight)
The specific gravity of each rubber composition vulcanized at 150 ° C. for 30 minutes was measured and indicated as an index with the value of Comparative Example 1 being 100. The smaller the value, the lower the weight.

  The results obtained from the test are shown in Table 1.

  From the results shown in Table 1, the conventional method of blending clay improves initial adhesion performance and deterioration-resistant adhesion, but reduces fatigue resistance and weight reduction (Comparative Example 2), whereas collagen particles It can be seen that the method of blending 1 improves not only the initial adhesion performance and deterioration-resistant adhesion, but also fatigue resistance and weight reduction (Example 1). When the collagen particles 2 having a large particle diameter were blended, the initial adhesion performance, the deterioration-resistant adhesion and the weight reduction were improved, but the fatigue resistance was lowered (Comparative Example 3).

Claims (4)

A rubber composition for steel cord coating comprising a rubber component and collagen particles having an average particle diameter of 20 μm or less. The rubber composition for steel cord coating according to claim 1, comprising 3 to 30 parts by weight of collagen particles having an average particle diameter of 20 µm or less with respect to 100 parts by weight of the rubber component. The rubber composition for steel cord coating according to claim 1 or 2, comprising a cobalt salt of an organic acid. A steel cord / rubber composite comprising the rubber composition according to claim 1, 2 or 3 and a steel cord.