Rubber composition for metal bonding

Abstract

The present invention discloses a rubber composition for metal bonding which includes 40-80 parts by mass of carbon black and silica in total per 100 parts by mass of a diene-based rubber and contains a specific disulfide compound and / or a C12-C20 fatty acid in an amount of 0.2-20 mass% with respect to the silica, the ratio between the silica and the carbon black being 1.0 or higher.

Description

Rubber composition for metal bonding

[0001] The present invention relates to a rubber composition for metal bonding, and more specifically, to a rubber composition for metal bonding that has sufficient hardness and tackiness for practical use, low viscosity, low rolling resistance, and excellent adhesion after moist heat aging.

[0002] A pneumatic tire is primarily composed of a pair of bead sections and sidewall sections, and a tread section that extends from both sidewall sections. A carcass layer is provided on the inside of the tire, and both ends of the carcass layer are folded back to enclose the bead core from the inside to the outside of the tire. The tread section consists of a cap tread and an under tread, and a belt layer is placed between the under tread and the carcass layer. Because this belt layer is subjected to strong impacts and heavy loads, steel wire coated with a metal-plated compound is used as a reinforcing material. The rubber covering such steel wire requires good adhesion to the steel wire.

[0003] On the other hand, from a carbon neutrality perspective, there is a demand for tires with reduced rolling resistance. The belt layer is no exception, and there is a need to switch from conventional carbon-based materials to silica-based materials. However, silica-based materials have problems such as increased viscosity, decreased hardness, and deterioration of wire adhesion after moisture aging, as well as a deterioration in tackiness (adhesion over time). In particular, regarding processability, sufficient tackiness improves splice workability and makes it easier to bond each component.

[0004] Furthermore, Patent Documents 1 to 4 below disclose techniques for incorporating disulfide compounds to improve the processability of rubber compositions.

[0005] Patent No. 5248211 Patent No. 4768521 Patent No. 6147585 Patent No. 6522091

[0006] The object of the present invention is to provide a rubber composition for metal bonding that has sufficient hardness and tackiness for practical use, low viscosity, low rolling resistance, and excellent adhesion after moist heat aging.

[0007] The present invention provides a rubber composition for metal bonding, characterized in that, with respect to 100 parts by mass of a diene rubber containing 50 parts by mass or more of natural rubber and / or synthetic isoprene rubber, the composition contains 40 to 80 parts by mass of carbon black and silica in total, and at least one selected from the group consisting of a disulfide compound represented by the following formula (1) and a fatty acid having 12 to 20 carbon atoms in an amount of 0.2 to 20% by mass relative to the silica, wherein the ratio of silica to carbon black is 1.0 or more as the former / latter (mass ratio).

[0008]

[0009] (In formula (1), R1 and R2 each represent substituents that can independently form an amide bond with an NH group.)

[0010] The rubber composition for metal bonding of the present invention contains 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber and / or synthetic isoprene rubber, 40 to 80 parts by mass of carbon black and silica in total, and 0.2 to 20% by mass of at least one selected from the group consisting of disulfide compounds represented by formula (1) and fatty acids having 12 to 20 carbon atoms relative to the silica, and the ratio of silica to carbon black as the former / latter (mass ratio) is 1.0 or more, so it has sufficient hardness and tackiness for practical use, low viscosity, low rolling resistance, and excellent adhesion after moist heat aging.

[0011] The present invention will be described in further detail below. The diene rubber used in the metal adhesive rubber composition of the present invention is essential to be natural rubber (NR) and / or synthetic isoprene rubber (IR). The amount of NR and / or IR must be 50 parts by mass or more when the total diene rubber is 100 parts by mass. If the amount of NR and / or IR is less than 50 parts by mass, the tensile strength deteriorates, which is undesirable. In addition to NR and IR, other diene rubbers can be used, such as butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), and acrylonitrile-butadiene copolymer rubber (NBR). These may be used alone or in combination of two or more. Furthermore, their molecular weight and microstructure are not particularly limited, and they may be end-modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl groups, etc., or epoxidized. The amount of NR and / or IR blended is preferably 80 parts by mass or more when the total diene rubber is 100 parts by mass. The weight-average molecular weight (Mw) of the diene rubber is not particularly limited, but for reasons of superior effects of the present invention, it is preferably 100,000 to 5,000,000, more preferably 200,000 to 3,000,000, and even more preferably 300,000 to 2,000,000. In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are standard polystyrene equivalent values ​​obtained by gel permeation chromatography (GPC) measurement.

[0012] The rubber composition for metal bonding in the present invention comprises carbon black and silica. From the viewpoint of improving the effects of the present invention, the carbon black preferably has the following embodiments: (1) The specific surface area of ​​the CTAB is 75 to 95 g / m². ２ Preferably, 80-90 g / m ２ (2) The compressed DBP oil absorption amount (24M4DBP) is preferably 60 to 85 ml / 100 ml, and more preferably 70 to 80 ml / 100 ml. (3) Nitrogen adsorption specific surface area N ２ SA (unit: m) ２N is the ratio of (mg / g) to the iodine adsorption amount IA (unit mg / g). ２ SA / IA is preferably 1.10 or less, and more preferably 0.85 to 1.05. In this specification, the CTAB specific surface area is measured in accordance with JIS K6217-2, and the compressed DBP (24M4DBP) is measured as the 24M4-DBP oil absorption amount based on JIS K6217-4 (compressed sample), and the nitrogen adsorption specific surface area N ２ SA is measured in accordance with JIS K6217-2, and iodine adsorption amount IA is measured in accordance with JIS K6217-1.

[0013] The silica used in this invention has a nitrogen adsorption specific surface area N, which is important for improving the effects of the present invention. ２ SA is 100-200m ２ It is preferable that the amount is / g. The type of silica that can be used is not particularly limited, and silica made from biomass materials such as rice husks may be used.

[0014] The rubber composition for metal bonding in the present invention comprises at least one selected from the group consisting of a disulfide compound represented by the following formula (1) and a fatty acid having 12 to 20 carbon atoms.

[0015]

[0016] (In formula (1), R1 and R2 each represent substituents that can independently form an amide bond with an NH group.)

[0017] Among the disulfide compounds represented by formula (1), dibenzamide diphenyl disulfide represented by the following formula is particularly preferred.

[0018]

[0019] Commercially available dibenzamide diphenyl disulfide can be used, such as dibenzamide diphenyl disulfide manufactured by Tokyo Chemical Industry Co., Ltd. or Noctizer SD manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzamide diphenyl disulfide is commonly used as a deconjugate (mixing accelerator) when compounding diene-based rubber (see, for example, Patent Document 3: Japanese Patent No. 6147585). On the other hand, in a preferred embodiment of the present invention, it is preferable to have at least a mixing step in which the diene-based rubber, the carbon black, the silica, and the disulfide compound represented by formula (1) are mixed simultaneously. Adopting such a mixing step further improves hardness and adhesion after moist heat aging. After the mixing step is completed, it is preferable to add other components to the obtained mixture and mix to prepare a rubber composition for metal adhesion.

[0020] The fatty acids having 12 to 20 carbon atoms used in the metal adhesive rubber composition of the present invention include saturated or unsaturated linear or branched fatty acids having 12 to 20 carbon atoms, preferably saturated linear fatty acids having 12 to 20 carbon atoms, and more preferably saturated linear fatty acids having 14 to 20 carbon atoms.

[0021] (Formulation ratio of rubber composition for metal bonding) The rubber composition for metal bonding in the present invention contains, with respect to 100 parts by mass of diene rubber, 40 to 80 parts by mass of carbon black and silica in total, and at least one selected from the group consisting of a disulfide compound represented by formula (1) and a fatty acid having 12 to 20 carbon atoms, in an amount of 0.2 to 20% by mass relative to the silica, and the ratio of silica to carbon black is 1.0 or more as the former / latter (mass ratio).

[0022] If the total amount of carbon black and silica is less than 40 parts by mass, the hardness and adhesion after moist heat aging will decrease, while if it exceeds 80 parts by mass, the viscosity will increase, worsening the processability. If the amount of at least one compound selected from the group consisting of the disulfide compound represented by formula (1) and fatty acids having 12 to 20 carbon atoms is less than 0.2% by mass relative to silica, the amount is too small to achieve the effects of the present invention, while if it exceeds 20% by mass, the adhesion after moist heat aging will decrease. If the ratio of silica to carbon black as the former / latter (mass ratio) is less than 1.0, the adhesion after moist heat aging will decrease.

[0023] The total amount of carbon black and silica is preferably 50 to 70 parts by mass per 100 parts by mass of diene rubber. The amount of at least one selected from the group consisting of a disulfide compound represented by formula (1) and a fatty acid having 12 to 20 carbon atoms is preferably 0.2 to 15.0% by mass, and more preferably 2.0 to 13.0% by mass, relative to the silica. The ratio of silica to carbon black is preferably 1.2 to 5.0, and more preferably 1.5 to 3.0, as the former / latter (mass ratio).

[0024] (Other Components) In addition to the components mentioned above, the rubber composition for metal bonding in the present invention may contain various additives commonly used in rubber compositions, such as vulcanizing or crosslinking agents; vulcanizing or crosslinking accelerators; zinc oxide; various fillers such as clay, talc, calcium carbonate, aluminum oxide, and titanium oxide; various oils; antioxidants; plasticizers; fatty acid cobalt, etc. Such additives can be mixed in a conventional manner to form a composition which can then be used for vulcanization or crosslinking. The amounts of these additives can also be the conventional amounts, as long as they do not contradict the purpose of the present invention.

[0025] Furthermore, the rubber composition for metal bonding in the present invention can achieve the effects of the present invention well by having one or more of the following forms (A) to (H). (A) Contains 2 to 10% by mass of a silane compound represented by the following formula (11) relative to the silica.

[0026]

[0027] (In formula (11), R １ and R ２ are hydrocarbon groups having 1 to 20 carbon atoms, and R ３ is a hydrocarbon group having 1 to 3 carbon atoms or hydrogen. R １ to R ３ may contain heteroatoms (however, sulfur is not included). n represents a number from 0 to 2.)

[0028] (B) Stearic acid is used together with the disulfide compound represented by the formula (1). (C) In a constant strain fatigue test at a strain of 60% and 400 rpm, the number of repetitions until fracture is 40,000 times or more. The constant strain fatigue test complies with JIS K6251, uses a test piece punched out in the shape of a JIS No. 3 dumbbell, and performs a tensile constant strain fatigue test under the conditions of 20°C, a strain of 60%, and a test frequency of 6.67 Hz (rotation speed 400 rpm) based on JIS K6270, and measures the number of repeated deformations until fracture. (D) In the silane compound represented by the formula (11), n is 0, R １ is an alkyl group having 7 to 20 carbon atoms, and R ３(E) The metal adhesive rubber composition further contains, per 100 parts by mass of the diene rubber, 0.1 to 1.5 parts by mass of organic acid cobalt salt as cobalt amount, 0.5 parts by mass or more and less than 3.0 parts by mass of phenolic resin, and 0.5 to 5.0 parts by mass of curing agent. Examples of organic acid cobalt salts include cobalt naphthenate, cobalt neodecanoate, cobalt stearate, cobalt rosinate, cobalt versatate, cobalt tall oilate, cobalt neodecanoate borate, and cobalt acetylacetonate. Examples of phenolic resins include cresol resin, resorcinol resin, alkylphenol resin, and modified phenolic resin. Examples of modified phenolic resins include cashew-modified phenolic resin, oil-modified phenolic resin, epoxy-modified phenolic resin, aniline-modified phenolic resin, and melamine-modified phenolic resin. Examples of curing agents include hexamethylenetetramine, hexamethoxymethylmelamine (HMMM), hexamethoxymethylolmelamine, pentamethoxymethylmelamine, hexaethoxymethylmelamine, a polymer of para-formaldehyde, and an N-methylol derivative of melamine. (F) The silica content is 55 to 70% by mass relative to the total amount of carbon black and silica. (G) The metal adhesive rubber composition contains 12 parts by mass or more, preferably 12 to 18 parts by mass, of zinc oxide per 100 parts by mass of the diene rubber. (H) As a vulcanization accelerator, 0.1 to 1.5 parts by mass of N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (for example, Noxellar DZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) is added per 100 parts by mass of the diene rubber.

[0029] The rubber-metal composite of the present invention is formed by embedding a wire in the rubber composition for metal adhesion of the present invention. Examples of the wire include a steel wire coated with a plating compound, and the plating compound is preferably brass plating, copper-tin plating, copper plating, zinc plating, nickel plating, chromium plating, or copper-zinc-cobalt ternary plating. In addition, examples of the uses of the rubber-metal composite of the present invention include tires, belt conveyors, electric wires, hoses, seismic isolation rubbers, etc. In the case of tire use, the rubber-metal composite includes belts embedded in the undertread, carcasses, and beads (including bead cores and steel cords housed therein).

[0030] The rubber-metal composite of the present invention can be obtained, for example, by mixing the above various components using a general-purpose mixer such as a Banbury mixer or a roll mixer to prepare a rubber composition for metal adhesion, embedding a wire therein, and then vulcanizing it according to a conventional method.

[0031] Further, when the rubber-metal composite of the present invention is used for tire applications, its manufacturing method is not particularly limited, and a tire can be manufactured according to known techniques. The tire is preferably a pneumatic tire and can be filled with an inert gas such as air or nitrogen and other gases.

[0032] Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples.

[0033] Standard Example, Examples 1-8, Comparative Examples 1-8 In the formulations (parts by mass) shown in Tables 1 and 2, diene rubber, carbon black, silica, and the disulfide compound represented by formula (1) were simultaneously mixed for 5 minutes using a 1.7-liter sealed Banbury mixer. The other components were then added to the resulting mixture and kneaded to prepare an unvulcanized metal adhesive rubber composition. Subsequently, the unvulcanized rubber composition was vulcanized at 170°C for 10 minutes to produce vulcanized rubber test specimens. Various physical properties of the unvulcanized rubber composition were measured as follows. For the wire pull-out test (wire adhesion after hot water degradation), a wire was coated with the unvulcanized rubber composition, and the test specimen vulcanized under the vulcanization conditions was immersed in hot water at 70°C for 4 weeks to perform a hot water degradation treatment to obtain a test specimen after hot water degradation, and the test was performed under the following conditions. Brass-plated steel wire was used as the wire.

[0034] Viscosity: For the unvulcanized rubber composition, the Mooney viscosity ML(1+4) at 100°C was determined using an L-shaped rotor in accordance with JIS K6300. The results are expressed as an index, with the standard example value set to 100. A smaller index indicates lower viscosity and better processability.

[0035] Heat generation: For the vulcanized rubber test piece, tanδ(60°C) was measured using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., under the conditions of initial strain 10%, amplitude ±2%, frequency 20 Hz, and temperature 60°C. The results are shown exponentially, with the standard value set to 100. A smaller value indicates lower heat generation and lower rolling resistance.

[0036] Hardness Hs: The hardness of the vulcanized rubber test specimen was measured at 20°C using a Type A durometer in accordance with JIS K6253. The results are expressed as an index, with the standard value set to 100. A higher index indicates higher hardness.

[0037] Pull-out force: In accordance with ASTM D-2, the steel wire was pulled out from the test specimen after hot water degradation, and the pull-out force was measured. The results are expressed as an index with the standard example value set to 100. A higher value indicates better adhesion to rubber after hot water degradation.

[0038] Rubber adhesion amount: In accordance with ASTM D-2229, the amount of rubber adhesion was measured by pulling out steel wires from the test specimens after hot water degradation. The results are expressed as an index with the standard example value set to 100. A higher value indicates better adhesion to rubber after hot water degradation.

[0039] Tackiness: The obtained unvulcanized rubber composition was molded into a sheet-like sample (10 mm wide x 200 mm long x 2 mm thick) without vulcanization, and this was set on a metal disc. Furthermore, a sample to be pressed (70 mm wide x 100 mm long x 2 mm thick) was molded from the same rubber composition without vulcanization. The sheet-like sample was pressed onto this sample to be pressed with 4.9 N of pressure, and after 3 hours, the attached sheet-like sample (unvulcanized) was peeled off, and the adhesive force required to peel it off was measured using a PICMA tack meter (manufactured by Toyo Seiki Seisakusho Co., Ltd.). The obtained results were expressed as an index with the standard value set to 100. A larger index indicates higher tackiness over time (adhesion over time), which makes it easier to bond each component and thus indicates superior processability.

[0040] Constant Strain Fatigue Test: The vulcanized rubber test specimens were punched into a JIS No. 3 dumbbell shape in accordance with JIS K6251, and a tensile constant strain fatigue test was performed on these specimens under the conditions of 20°C, 60% strain, and a test frequency of 6.67 Hz (rotation speed of 400 rpm), referring to JIS K6270, and the number of repeated deformations until failure was measured. The results are shown in Tables 1 and 2.

[0041]

[0042]

[0043] *1: NR (RSS #3) *2: Carbon Black CB (Tokai Carbon Co., Ltd. Seast 300, CTAB specific surface area = 86 g / m²) ２ , Compressed DBP oil absorption (24M4DBP) = 75ml / 100ml, N ２SA / IA = 1.024) *3: Silica (Precipitated silica K160, manufactured by FengHai Rice Biotechnology) *4: Silane coupling agent 1 (Si69, manufactured by Evonik Degussa, bis(3-triethoxysilylpropyl) tetrasulfide) *5: Zinc oxide (3 types of zinc oxide, manufactured by Seido Chemical Industries, Ltd.) *6: Disulfide compound (Dibenzamide diphenyl disulfide, manufactured by Tokyo Chemical Industries, Ltd.) *7: Stearic acid (Beads stearic acid YR, manufactured by NOF Corporation) *8: Anti-aging agent (6PPD, manufactured by Flexis) *9: Organic acid cobalt salt (DICNATE NBC-II, manufactured by DIC Corporation, cobalt borate neodecanoate) *10: Sulfur (Crystex HT OT 20, manufactured by AkzoNobel K.K.) *11: Vulcanization accelerator 1 (Noxellar DZ, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *12: Vulcanization accelerator 2 (Noxellar CZ-G, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *13: Silane compound (KBE-3083, octyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) *14: Silane coupling agent 2 (Si75, bis(3-triethoxysilylpropyl) disulfide, manufactured by Evonik de Gussa)

[0044] From the results in Table 1, it can be seen that the metal bonding rubber composition of each example contains 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber and / or synthetic isoprene rubber, 40 to 80 parts by mass of carbon black and silica in total, and at least one selected from the group consisting of disulfide compounds represented by the following formula (1) and fatty acids having 12 to 20 carbon atoms in an amount of 0.2 to 20% by mass relative to the silica, and the ratio of silica to carbon black as the former / latter (mass ratio) is 1.0 or more. Therefore, compared to the standard example, it can be seen that it has practically sufficient hardness and tackiness, low viscosity, low rolling resistance, and excellent adhesion after moist heat aging. In Comparative Example 1, the total amount of carbon black and silica was below the lower limit specified in the present invention, so the hardness and pull-out strength were reduced. In Comparative Example 2, the ratio of carbon black and silica was below the lower limit specified in the present invention, so the heat generation, rubber adhesion amount, tackiness, and constant strain fatigue test results were reduced. Comparative Example 3 showed a decrease in heat generation, tensile strength, rubber adhesion, tackiness, and constant strain fatigue test results because the ratio of carbon black and silica was below the lower limit specified in the present invention. Comparative Example 4 showed a decrease in heat generation, tensile strength, rubber adhesion, and tackiness because the amount of disulfide compound and fatty acid with 12 to 20 carbon atoms exceeded the upper limit specified in the present invention. Comparative Example 5 showed a decrease in hardness and tensile strength because the total amount of carbon black and silica was below the lower limit specified in the present invention. Comparative Example 6 showed the same results as the standard example because the amount of fatty acid with 12 to 20 carbon atoms was below the lower limit specified in the present invention, and the effects of the present invention could not be achieved. Comparative Example 7 showed a decrease in tensile strength, rubber adhesion, and tackiness because the amount of fatty acid with 12 to 20 carbon atoms exceeded the upper limit specified in the present invention. Comparative Example 8 showed a deterioration in viscosity and heat generation because the total amount of carbon black and silica exceeded the upper limit specified in the present invention.

[0045] The present invention encompasses the following embodiments. Embodiment 1: A rubber composition for metal bonding, characterized in that, with respect to 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber and / or synthetic isoprene rubber, the composition contains 40 to 80 parts by mass of carbon black and silica in total, and at least one selected from the group consisting of a disulfide compound represented by the following formula (1) and a fatty acid having 12 to 20 carbon atoms in an amount of 0.2 to 20% by mass relative to the silica, wherein the ratio of silica to carbon black is 1.0 or more as the former / latter (mass ratio).

[0046]

[0047] (In formula (1), R1 and R2 each represent substituents that can independently form an amide bond with an NH group.) Embodiment 2: The metal-adhesive rubber composition according to Embodiment 1, characterized in that the disulfide compound is dibenzamide diphenyl disulfide. Embodiment 3: The metal-adhesive rubber composition according to Embodiment 1 or 2, characterized in that the metal-adhesive rubber composition contains a silane compound represented by the following formula (11), and the amount of the silane compound is 2 to 10% by mass relative to the silica.

[0048]

[0049] (In formula (11), R １ and R ２ R is a hydrocarbon group having 1 to 20 carbon atoms. ３ R is a hydrocarbon group having 1 to 3 carbon atoms or hydrogen. １ ~R ３ n may contain heteroatoms (but not sulfur). n represents a number from 0 to 2.) Embodiment 4: A metal adhesive rubber composition according to any one of Embodiments 1 to 3, characterized in that in a constant strain fatigue test under conditions of 60% strain and 400 rpm, the number of repetitions until the metal adhesive rubber composition is destroyed is 40,000 or more. Embodiment 5: In the silane compound represented by formula (11), n ​​is 0, and R １ R is an alkyl group having 7 to 20 carbon atoms. ３A metal-adhesive rubber composition according to Embodiment 3, characterized in that the group is an ethyl group. Embodiment 6: A metal-adhesive rubber composition according to any one of Embodiments 1 to 5, characterized in that when the total diene rubber is 100 parts by mass, it contains 80 parts by mass or more of the natural rubber and / or synthetic isoprene rubber. Embodiment 7: The CTAB specific surface area of ​​the carbon black is 75 to 95 g / m². ２ A metal-adhesive rubber composition according to any one of Embodiments 1 to 6, characterized in that the compressed DBP oil absorption amount (24M4DBP) of the carbon black is 60 to 85 ml / 100 ml, as described in Embodiment 8. A metal-adhesive rubber composition according to any one of Embodiments 1 to 7, characterized in that the compressed DBP oil absorption amount (24M4DBP) of the carbon black is 60 to 85 ml / 100 ml. Embodiment 9: Nitrogen adsorption specific surface area N of the carbon black ２ SA (unit: m) ２ N is the ratio of (mg / g) to the iodine adsorption amount IA (unit mg / g). ２ A metal-adhesive rubber composition according to any one of Embodiments 1 to 8, characterized in that SA / IA is 1.10 or less. Embodiment 10: Nitrogen adsorption specific surface area N of the silica ２ SA is 100-200m ２ A rubber composition for metal bonding according to any one of Embodiments 1 to 9, characterized in that it is / g. Embodiment 11: A rubber-metal composite comprising a wire embedded in the rubber composition for metal bonding according to any one of Embodiments 1 to 10. Embodiment 12: A rubber-metal composite according to Embodiment 11, characterized in that the wire is a steel wire coated with a plating compound. Embodiment 13: A rubber-metal composite according to Embodiment 12, characterized in that the plating compound is brass plating, copper-tin plating, copper plating, zinc plating, nickel plating, chromium plating, or copper-zinc-cobalt ternary plating. Embodiment 14: A tire, belt conveyor, electric wire, hose, or seismic isolation rubber using the rubber-metal composite according to any one of Embodiments 11 to 13. Embodiment 15: A tire using the rubber-metal composite according to any one of Embodiments 11 to 13.

Claims

1. A rubber composition for metal bonding characterized in that, per 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber and / or synthetic isoprene rubber, the composition contains 40 to 80 parts by mass of carbon black and silica in total, and at least one selected from the group consisting of a disulfide compound represented by the following formula (1) and a fatty acid having 12 to 20 carbon atoms in an amount of 0.2 to 20% by mass relative to the silica, wherein the ratio of silica to carbon black is 1.0 or more as the former / latter (mass ratio). (In formula (1), R1 and R2 each represent substituents that can independently form an amide bond with an NH group.) 2. The metal bonding rubber composition according to claim 1, characterized in that the disulfide compound is dibenzamide diphenyl disulfide.

3. The metal-adhesive rubber composition according to claim 1, characterized in that the metal-adhesive rubber composition comprises a silane compound represented by the following formula (11), and the amount of the silane compound blended is 2 to 10% by mass relative to the silica. (In formula (11), R １ and R ２ R is a hydrocarbon group having 1 to 20 carbon atoms. ３ R is a hydrocarbon group having 1 to 3 carbon atoms or hydrogen. １ ~R ３ (The compound may contain heteroatoms (but not sulfur). n represents a number between 0 and 2.) 4. The metal adhesive rubber composition according to claim 1, characterized in that, in a constant strain fatigue test under conditions of 60% strain and 400 rpm, the number of cycles until the metal adhesive rubber composition is destroyed is 40,000 or more.

5. In the silane compound represented by formula (11), n ​​is 0, and R １ R is an alkyl group having 7 to 20 carbon atoms. ３ The rubber composition for metal bonding according to claim 3, characterized in that the group is an ethyl group.

6. The metal bonding rubber composition according to claim 1, characterized in that it contains 80 parts by mass or more of natural rubber and / or synthetic isoprene rubber when the total diene rubber is 100 parts by mass.

7. The CTAB specific surface area of ​​the carbon black is 75 to 95 g / m². ２ The rubber composition for metal bonding according to claim 1, characterized in that it is the same as the one described in claim 1.

8. The metal bonding rubber composition according to claim 1, characterized in that the compressed DBP oil absorption amount (24M4DBP) of the carbon black is 60 to 85 ml / 100 ml.

9. The nitrogen adsorption specific surface area N ２ SA (unit: m ２ / g) and the ratio of iodine adsorption amount IA (unit: mg / g), N ２ SA / IA is 1.10 or less, and the rubber composition for metal adhesion according to claim 1, characterized in that.

10. Nitrogen adsorption specific surface area of ​​the silica N ２ SA is 100-200m ２ The rubber composition for metal bonding according to claim 1, characterized in that it is / g.

11. A rubber-metal composite comprising a wire embedded in the metal-adhesive rubber composition according to claim 1.

12. The rubber-metal composite according to claim 11, characterized in that the wire is a steel wire coated with a plating compound.

13. The rubber-metal composite according to claim 12, characterized in that the plating compound is brass plating, copper-tin plating, copper plating, zinc plating, nickel plating, chromium plating, or copper-zinc-cobalt ternary plating.

14. A tire, belt conveyor, electric wire, hose, or seismic isolation rubber using the rubber-metal composite described in claim 11.

15. A tire using the rubber-metal composite according to claim 11.

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