JP6645349B2 - Rubber-steel cord composite - Google Patents

Description

  The present invention relates to a rubber-steel cord composite in which a steel wire, such as a steel cord, is embedded in a rubber product, for the purpose of reinforcing various rubber products, for example, by suppressing corrosion and progress of corrosion of the steel wire. An object of the present invention is to provide a rubber-steel cord composite containing a water-soluble rust inhibitor in rubber covering a steel cord and capable of suppressing deterioration of adhesion to rubber and corrosion fatigue.

2. Description of the Related Art In general, rubber products such as tires and conveyors use, for reinforcement, steel wires coated on the surface with brass plating (copper-zinc alloy plating). The causes of shortening the life of rubber products reinforced with these plated steel wires include corrosion of the steel wires and corrosion fatigue caused by the corrosion. Rubber used for tires and conveyors is permeable to water and oxygen, and rubber products contain water because various additives are used to give the rubber the desired performance. At this time, the steel wire for reinforcing rubber products is exposed to a corrosive environment and corrodes.
In addition, various external and internal factors during use may damage the rubber product and promote water penetration, thereby promoting corrosion. As a result, the rubber peels off from the steel wire due to corrosion or breaks earlier than the original fatigue life of the steel wire due to corrosion fatigue, so the life of the rubber product is shorter than the original fatigue life of the steel wire There was a problem.

For such a problem, Sn, Zn, and Bi are plated before the final heat treatment performed before the brass plating process as a technology for suppressing the decarburization of the wire and improving the fatigue characteristics and improving the corrosion resistance. A technique (Patent Document 1) and a technique of plating Ni (Patent Document 2) have been proposed.
However, although these technologies have contributed to the suppression of decarburization, corrosion occurs as in conventional rubber products, especially if the coating is damaged by various external and internal factors during the wire drawing process and during use. did.
As a technique for suppressing corrosion of a wire, for example, a technique of applying a metal having a higher ionization tendency than iron to at least one steel filament located inside the outermost layer strand of the wire (for example, Patent Document 3) discloses that, while the metal having a high ionization tendency remains, the corrosion of the wire is suppressed, but the metal having a high ionization tendency is easily corroded and consumed in a short period of time. The improvement was not enough.
Another technique has been proposed in which the surface of a wire is protectively coated with a corrosion inhibitor composed of a metal oxide, a rare earth metal salt and an organic acid salt (for example, Patent Document 4). No consideration was given to adhesion, and corrosion of the wire was suppressed, but adhesion was insufficient.
Also, a technique for improving the adhesion between a wire and rubber by incorporating a porous inorganic filler selected from silica, aluminum hydroxide, aluminum oxide, calcium carbonate, magnesium carbonate, clay, and zeolite into a rubber composition has been proposed. Although it is disclosed (for example, Patent Document 5), this is because the vulcanization reaction is promoted by moisture contained in the porous inorganic filler, and does not contribute to corrosion resistance at all.

Japanese Patent No. 5602657 JP 2012-167380 A JP 2015-196937 A Japanese Patent No. 5649732 JP-A-2002-13083

As described above, in the conventional technology, there is a technology for suppressing corrosion, in particular, for suppressing the progress of corrosion when a scratch is present on the plating layer, and for sufficiently suppressing the peeling of rubber from a steel wire and corrosion fatigue. Did not.
The present invention has been made in view of the above circumstances, and is a rubber-metal composite in which a steel wire is embedded, which can suppress deterioration of adhesion to rubber by suppressing corrosion and progress of corrosion of steel, and can suppress corrosion fatigue. The purpose is to provide the body.

The present inventors have conducted a detailed investigation on the corrosion of a brass-plated steel wire, which is a typical example of a steel wire coated with rubber, and as a result, it has been found that steel is lost from the noble coating of the brass plating which is a noble film applied to the steel wire. Corrosion begins preferentially, and pitting of steel progresses below the noble plating layer with the progress of corrosion, and rust expansion and destruction causes peeling of the coating layer such as brass plating, which is the adhesion layer with rubber, Was found to occur.
At the same time, it was found that corrosion fatigue progressed from a pit-like corrosion site as a starting point, leading to early fracture. Based on these findings, it was considered effective to suppress the progress of corrosion in exposed steel parts such as defects in brass plating. The present inventors have found that the incorporation of a rust inhibitor that forms a film on the cord surface can suppress the progress of steel corrosion, and completed the present invention. The summary is as follows.

[1] A rubber-steel cord composite in which a rubber coating layer is laminated on a steel cord surface via a film for improving adhesion to the rubber coating layer, wherein the rubber coating layer has a rubber component of 100 A rubber-steel cord composite, comprising 0.1 to 160.0 parts by mass of a water-soluble rust inhibitor based on parts by mass.
[2] The rubber-steel cord composite according to [1], wherein the thickness of the rubber coating layer containing the water-soluble rust inhibitor is 0.5 μm or more.
[3] The rubber-steel according to [1] or [2], further including a rubber layer not containing a water-soluble rust inhibitor outside the rubber coating layer containing the water-soluble rust inhibitor. Code complex.
[4] The rubber-steel cord composite according to any one of [1] to [3], wherein the steel cord is a steel wire having a tensile strength of 1000 MPa or more.
[5] The film for the purpose of improving the adhesion contains Cu, and further contains at least one or more elements selected from Ni, Sn and Zn [1] to [4]. The rubber-steel cord composite according to any one of the above.
[6] The rubber-steel cord composite according to [5], wherein the film for improving the adhesion is brass plating.

  Normally, additives used for rubber are added to improve and adjust the performance of rubber, and even if such additives are dissolved when water is contained or water enters from the cut part, In addition, the conductivity is improved to promote corrosion. Further, in the stranded state, it is difficult for rubber to enter between the wires, and there is a gap, and once water enters, the water penetrates the gap to promote corrosion. On the other hand, in the rubber-steel cord composite according to the present invention, the rubber composition for coating the steel cord contains an inorganic rust preventive that dissolves in water and reacts with metal to form a dense film. As a result, in a corrosive environment, the water-soluble rust inhibitor dissolves and reaches the surface of the steel cord to form a dense film having good adhesion. This dense film serves as a barrier against corrosion factors, effectively suppressing the progress of corrosion of steel, suppressing the separation of rubber, and suppressing pitting. As a result, according to the rubber-steel cord composite according to the present invention, it is possible to suppress the deterioration of the adhesion between the metal and the rubber and the corrosion fatigue.

  Hereinafter, the rubber-steel cord composite according to the present invention will be described in detail. Note that these embodiments do not limit the present invention. The components of the above-described embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially equivalent. Furthermore, those skilled in the art can arbitrarily combine various forms included in the above-described embodiments within a range obvious to those skilled in the art.

<Rubber composition>
The rubber-steel cord composite according to the present invention comprises 0.1 parts by mass of a rust preventive that dissolves in water to form a film on a metal surface in a rubber composition that coats a steel cord with respect to 100 parts by mass of a rubber component. Not less than 160.0 parts by mass. Here, each part by mass is indicated by a relative value when the total mass of the rubber including the natural rubber and the synthetic rubber contained in the rubber composition is 100.

  Examples of the water-soluble rust inhibitor include phosphate compounds (for example, phosphoric acid, primary phosphate, secondary phosphate, tertiary phosphate, pyrophosphate, pyrophosphate, tripolyphosphate, tripolyphosphate). Condensed phosphates such as phosphates, phosphites, phosphites, hypophosphorous acid, hypophosphites, etc., vanadium compounds (eg, oxides, hydroxides, sulfides, and sulfuric acids of vanadium) , Carbonate, halide, nitride, fluoride, carbide, cyanide (thiocyanide) and salts thereof), niobium compound, zirconium compound, phosphate (eg, zinc phosphate, aluminum dihydrogen phosphate) , Zinc phosphite, etc.), molybdate, phosphomolybdate (eg, aluminum phosphomolybdate, etc.), vanadate, etc., organic phosphoric acid and salts thereof (eg, phytic acid, phytate) Phosphonic acids, phosphonates and their metal salts, such as alkali metal salts) can be applied. One or more of these may be used in combination.

  The type of the other rubber composition is not particularly limited, and for example, generally known natural rubber and synthetic rubber can be used alone or in combination of two or more. Examples of the synthetic rubber include diene rubbers such as butadiene rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-vinyl acetate rubber, chlorosulfonated polyethylene, and acrylic rubber. Olefin rubber, urethane rubber, fluorine rubber, polysulfide rubber and the like can be used.

  Further, in order to improve and adjust the performance of rubber, a compounding agent usually used in the rubber industry can be appropriately blended in a usual blending amount. Specifically, fillers such as carbon black and silica, softeners such as aroma oil, guanidines such as diphenylguanidine, thiazoles such as mercaptobenzothiazole, N, N'-dicyclohexyl-2-benzothiazolyl Vulcanization accelerators such as sulfenamides such as rusulfenamide, thiurams such as tetramethylthiuram disulfide, vulcanization accelerators such as zinc oxide, poly (2,2,4-trimethyl-1,21-dihydro Anti-aging agents such as quinoline) and amines such as phenyl-α-naphthylamine. The co-presence of these compounding agents commonly used in the rubber industry in the rubber does not affect the performance of the present invention.

  Furthermore, in the rubber-steel cord composite according to the present invention, a coating for improving the adhesion to the rubber coating layer is present on the surface of the steel cord. Such a coating is not particularly limited as long as it contributes to the improvement of the adhesion between the steel wire and the rubber. For example, a phosphate coating, a chromate coating, a trivalent chromium-treated coating, a silane coupling-treated coating, Examples thereof include a urethane resin film, an epoxy resin film, an acrylic resin film, and a Cu alloy film, and other known means can be applied without being limited to these. In particular, if necessary, two or more of the above-mentioned films can be combined and applied as a multilayer film.

(Action, etc.)
The water-soluble rust inhibitor contained in the rubber-steel cord composite dissolves in water that has penetrated into the rubber covering the steel cord, and improves the adhesion to the rubber. To form a dense, well-adhesive, hardly soluble film on the exposed steel surface. This dense and hardly soluble film having good adhesion serves as a barrier against corrosion factors and suppresses corrosion, so that a decrease in fatigue limit due to corrosion can be suppressed. Here, the term “poorly soluble” means that the solubility in water at 25 ° C. is less than 0.01 g / l.

  The solubility of this water-soluble rust inhibitor in water at 25 ° C. is desirably 0.01 g / l or more and less than 10 g / l. If the solubility in water at 25 ° C. is less than 0.01 g / l, a sufficient amount of a rust preventive to elute a film on the exposed portion of the steel cord surface is not eluted, and the rust preventive effect cannot be obtained. On the other hand, when the solubility in water at 25 ° C. is as high as 10 g / l or more, all the rust preventives are eluted at an early stage, which is not suitable for long-term rust preventive. In addition, since the affinity with water is too high, it is easy to take in moisture from the outside, and this causes a problem of promoting hydrolysis of the surrounding rubber. The more preferable range of the solubility is 0.05 g / l or more and 5 g / l or less.

  In the rubber-steel cord composite, by setting the amount of the water-soluble rust inhibitor to 100 parts by mass or more with respect to 100 parts by mass of the rubber component, the coating is dense and has good adhesion to the exposed steel portion on the surface of the steel cord. Can be formed. The above effect can be achieved at a higher level by setting the total content of the water-soluble rust inhibitor contained in the rubber covering the steel cord to 0.5 part by mass or more, and 1.0 mass The above effect can be achieved at an extremely high level by setting the number of parts to be greater than or equal to the number of parts.

  On the other hand, the water-soluble rust inhibitor contained in the rubber composition covering the steel cord, if the total exceeds 160.0 parts by mass with respect to 100 parts by mass of the rubber component, significantly impairs the physical properties of the rubber. It becomes unsuitable as a product. Therefore, the upper limit of the total amount of the water-soluble rust preventive contained in the rubber covering the steel cord was set to 160.0 parts by mass with respect to 100 parts by mass of the rubber component. In addition, it is a more preferable form that it is 80 parts by mass or less.

  As described above, in the rubber-steel cord composite according to the present invention, when exposed to a corrosive environment, the steel cord has good adhesion to the steel cord surface, and forms a dense film with high barrier properties. The type and amount of the rust inhibitor contained in the rubber composition covering the cord are limited to specific ones. As a result, according to the rubber-steel cord composite according to the present invention, it is possible to suppress deterioration of adhesion to rubber due to corrosion and suppression of corrosion fatigue. In addition, by including a rust preventive in the rubber composition, a coating for the purpose of improving the adhesion to rubber can be provided on the surface layer of the steel cord, so that the adhesion of the steel cord can be secured in the first place.

(Preferred example)
In the rubber-steel cord composite described above, by suppressing the thickness of the rubber coating layer containing the water-soluble rust inhibitor to 0.5 μm or more, it is possible to suppress deterioration of adhesion to rubber due to corrosion and to prevent corrosion. It is possible to effectively suppress fatigue. On the other hand, the upper limit of the thickness is not particularly limited, but is preferably 20000.0 μm or less in order to save the water-soluble rust inhibitor. In addition, a more preferable range of the thickness of the rubber coating layer containing the water-soluble rust preventive is 1.0 μm or more and 10000.0 μm or less, whereby the effect can be more stably enjoyed.

  Further, in the rubber-steel cord composite according to the present invention, it is a preferable embodiment to provide a rubber layer not containing a water-soluble rust inhibitor outside the rubber coating layer containing a water-soluble rust inhibitor. By having a layer that does not contain a water-soluble rust preventive on the outside, it is possible to prevent the water-soluble rust preventive from eluting to the external environment instead of the exposed steel part of the steel cord. The effect can be enjoyed for a longer period.

  The thickness of the rubber coating layer containing the water-soluble rust inhibitor can be measured by analyzing a cross-sectional sample prepared so that the vertical axis cross section of the steel cord is exposed, using EPMA or SEM-EDX.

  Further, a steel material having a tensile strength of 1000 MPa or more is preferably used for the steel wire in the present invention, and more preferably a steel material having a tensile strength of 2800 MPa or more is used. If the tensile strength is 1000 MPa, the plated steel wire can be preferably used as a reinforcing material for reinforcing rubber such as the above-mentioned tires and conveyors. The tensile strength of the plated steel wire can be measured by a tensile test based on JIS G3510 (1992) for a (steel) cord and JIS Z2241 (1998) for a filament.

  Examples of the steel wire having the above tensile strength include a high-carbon steel wire having a carbon content of about 0.8% by mass or more, and a wire diameter of about φ 0.05 mm to 0.4 mm.

The coating for improving the adhesion to rubber in the present invention is preferably a plating layer containing Cu and further containing at least one element selected from Ni, Sn and Zn. Above all, the use of brass plating (Cu-Zn plating) as an adhesion layer when embedded in vulcanized rubber is an even more preferable form because it has the effect of improving lubricity during wire drawing. Since S in the vulcanized rubber and Cu in the brass plating form a strong chemical bond, high adhesion can be obtained. The composition and thickness of the brass plating layer constituting the film for improving the adhesion to the rubber may be appropriately selected according to various demands, and is not particularly limited.
When a plating film other than brass plating or a chemical conversion treatment film is used as a film for improving the adhesion to the rubber coating layer, taking into consideration the extensibility and abrasion resistance of the film, forming the coating after wire drawing. You can also.

<Production method of rubber-steel cord composite>
As described above, the configuration of the steel wire according to the preferred embodiment of the present invention has been described in detail. Next, a method for manufacturing the rubber-steel cord composite will be described.

  First, a rolled or drawn steel wire is subjected to a final heat treatment for obtaining a uniform and fine pearlite structure, and then is pickled to remove the scale of the surface. Thereafter, final drawing is performed by a wet method to obtain a steel cord having a desired wire diameter and strength. At this time, as an acid solution used for pickling, for example, hydrochloric acid, sulfuric acid, or the like can be used.

  During the period from the final heat treatment to after the final drawing, a film is formed on the surface of the steel wire to ensure adhesion to the rubber coating layer. Known methods can be used for forming the film. For a phosphate film, a dipping or spraying method is used. For a chromate film or a trivalent chromium-treated film, a coating method or an electrolytic method is used. A urethane resin film, an epoxy resin film, or an acrylic resin film can be formed by a coating method, and a Cu alloy film can be formed by electroplating. The application method is not particularly limited, and an immersion method, a spray method, or the like can be applied. In any case, it is preferable to perform a degreasing and an acid activating treatment before the film forming treatment.

  In the case of a low spreadability such as a phosphate film, a chromate film and a trivalent chromium-treated film or a resin, it is desirable to form a film for securing adhesion after the final drawing. On the other hand, among the Cu alloy films, brass plating (Cu-Zn) and Cu-Sn plating have a high ductility and also act as a lubricating film at the time of final drawing by a wet method. desirable.

  Among the Cu alloy films, for brass plating (Cu-Zn) or Cu-Sn plating, alloy plating may be directly formed from a cyanide bath or pyrophosphate bath, but Cu plating and Zn plating, or The Cu plating and the Sn plating may be formed by individually plating and laminating each, and then heating to a temperature equal to or higher than the melting point of Zn or Sn and alloying by diffusion.

  Further, when the Cu alloy film is formed after the final drawing by the heat diffusion, the structure is annealed by the heat treatment, and the strength of the steel wire is reduced. Therefore, it is necessary to form the Cu alloy film before the final drawing. is there.

  A rubber composition obtained by mixing a water-soluble rust inhibitor with a steel cord having a coating formed on the surface of a steel wire to ensure adhesion with a rubber coating layer as described above, together with other additives, according to a standard method. Coated to form a rubber-steel cord composite with steel cord embedded in rubber. If necessary, a rubber composition containing no water-soluble rust inhibitor may be further coated on the outside.

  Finally, in order to improve the strength of the rubber composition, and when a Cu alloy plating is formed as a film for securing the adhesion, in order to improve the adhesion, the rubber-metal composite, The vulcanization treatment is performed at 170 ° C to 220 ° C for several minutes to several hours. As the vulcanizing agent used in the vulcanizing treatment, a known vulcanizing agent can be used. For example, sulfur and its congeners (Se, Te), sulfur-containing organic compounds, organic peroxides, metal oxides (MgO, (PbO, ZnO, etc.), organic polyamines, modified phenol resins, isocyanates, and various other materials can be used. During the vulcanization treatment, a vulcanization accelerator is added in addition to the vulcanizing agent for the purpose of shortening the vulcanizing time, lowering the vulcanizing temperature, reducing the amount of the vulcanizing agent, and improving the quality of the rubber product. You may.

  ADVANTAGE OF THE INVENTION According to the manufacturing method which concerns on this invention shown above, the corrosion of a steel wire and the progress of corrosion can be suppressed, and the rubber-steel cord composite which can suppress adhesion deterioration with rubber and corrosion fatigue can be obtained. Can be.

  Hereinafter, the effects of the present invention will be specifically described with reference to the invention examples. Note that the present invention is not limited to the conditions used in the following invention examples. The underlined portions in Table 1 mean that the values deviate from the scope of the present invention.

  Steel having a diameter of 5.5 mm by melting 0.8% by mass of C, 0.21% of Si, 0.42% of Mn, 0.007% of P, and 0.016% of S by mass%. Rolled into wire. The obtained hot-rolled material was pickled, scale was removed, and then drawn to a wire diameter of 1.8 mm. As a final heat treatment, the drawn wire was heated in a heating furnace at 950 ° C. for 2 minutes to austenitize, then rapidly cooled to 600 ° C. at a cooling rate of 100 ° C./s, and kept at that temperature for 10 seconds.

  The obtained steel wire is continuously subjected to electrolytic degreasing with an alkaline solution and electrolytic pickling with sulfuric acid, and as a film for ensuring adhesion with the rubber coating layer, an average thickness after wire drawing. Was formed by performing a brass plating with 230 nm and a Cu concentration of 63% by mass by performing Cu pyroplating plating and Zn sulfate plating in this order, and then performing an alloying process of heating to 500 ° C. and holding for 4 seconds. Thereafter, wire drawing was performed by wet wire drawing using a wet lubricant so that the wire diameter became 0.1 to 0.4 mm, to produce a thin steel wire. For comparison, a thin steel wire was produced without forming a film and only subjected to electrolytic degreasing with an alkaline solution and electrolytic pickling with sulfuric acid.

  When a film other than brass plating is formed as a film for ensuring adhesion with the rubber coating layer, the wire diameter is reduced to 0.1 to 0.4 mm by wet drawing using a wet lubricant, respectively. It was formed after wire drawing processing. Cu-Sn plating is performed by sequentially performing Cu pyrophosphate plating and Sn sulfate plating so that the average thickness after drawing is 230 nm and the Cu concentration is 80% by mass, and then heating to 400 ° C. for 4 seconds. It was formed by performing an alloying process for holding. Cu—Ni plating is performed by sequentially performing Cu pyrophosphate plating and Ni sulfate plating so that the average thickness after drawing is 230 nm and the Cu concentration is 80% by mass, and then heating to 800 ° C. for 5 minutes. It was formed by performing an alloying process for holding.

The phosphate film, silane coupling film, chromate film, and urethane resin film are immediately washed with water after forming the lower layer film, and the wire diameter is 0.1 to 0.4 mm by wet drawing using a wet lubricant. It was formed to have been subjected to wire drawing. Each of the phosphate films was formed using PBL-3080 manufactured by Nippon Parker Ling Co., Ltd. under ordinary chemical conversion treatment conditions so that the amount of adhesion was 3 g / m ² . The silane coupling treatment was immersed in 3-aminopropyltrimethoxysilane, pulled up and dried, and adjusted to a thickness of 0.3 μm. Chromate film ^{Cr 3+: 10~50g / l, Cr} 6+: 10~50g / l, SiO 2 colloids: pulling was immersed in 100 g / l partially-reduced coating type chromate treatment solution, at the highest temperature 160 ° C. It was adjusted to 300 mg / m ² by drying. The amount of adhesion was determined by X-ray fluorescence analysis. As an example of the resin film, the urethane resin film was immersed in an aqueous dispersion of a cationic polyurethane resin, pulled up, dried at a maximum temperature of 190 ° C., and adjusted to a thickness of 1 μm.

The obtained thin steel wires were twisted at a pitch of 5 mm to form a cord, which was set in a mold, and the rubber shown in Table 2 to which the water-soluble rust inhibitor shown in Table 1 was added in the amount shown in Table 1. The rubber composition shown in Table 2 without the water-soluble rust inhibitor was embedded in the composition so as to have a thickness shown in Table 1, and then laminated to a total thickness of 10 mm. Thereafter, vulcanization treatment was performed by a hot press heating at 160 ° C. for 30 minutes to prepare an evaluation sample.
Using a sample cut in the center of the sample with a cutter so that the plated steel wire was exposed in a direction perpendicular to the steel cord, the adhesion after the deterioration treatment and the presence or absence of pitting corrosion were evaluated. The adhesion after the deterioration treatment is measured by measuring the adhesive strength before and after the deterioration treatment, and when the strength before the deterioration treatment is set to 100, the strength after the deterioration treatment is less than 50 is C, and the strength is 50 or more and less than 70. Was evaluated as B, and those having 70 or more were evaluated as A, and B or more was evaluated as acceptable.
At this time, the adhesive strength was determined by measuring the pulling force when the cord was pulled out of the rubber with a tensile tester, and evaluated by the maximum pulling force.
Further, the deterioration treatment was performed by holding the sample in a constant temperature and humidity chamber at a relative humidity of 95% and a temperature of 80 ° C. for 300 hours. Regarding the presence or absence of pitting corrosion, a sample was taken from the drawn steel wire, and for the cross-sectional sample prepared by Cross Section Polisher (CP), the corrosion shape under the brass plating layer was confirmed by FE-SEM-EDX, When the depth of the pit-like corrosion was 1 μm or more, C was set if it was less than 1 μm, B was set if it was less than 0.5 μm, and B or more was set as acceptable. Table 1 shows the results.

  As for the corrosion fatigue, a stress load type fatigue test was performed in a neutral salt spray test environment based on JIS Z 2371 (2000). The evaluation of corrosion fatigue is represented by an index when the life of a sample using a rubber containing no water-soluble rust inhibitor (Comparative Example 1) is set to 100, C is 100 or less, B is 101 to 129, and 130 or more is B. A and B or more were judged as pass. Table 1 shows the results.

  According to Table 1, any of the examples of the present invention (including a water-soluble rust inhibitor in the rubber coating layer and having a film for the purpose of ensuring adhesion to rubber) has the following properties: Both the pit-like corrosion state and the corrosion fatigue were improved and passed. Therefore, it can be said that the rubber-steel cord composites of the examples were able to suppress the deterioration of the adhesion to the rubber and the corrosion fatigue by suppressing the corrosion of the steel cord and the progress of the corrosion.

  On the other hand, the comparative examples (in which the water-soluble rust inhibitor contained in the rubber was not adjusted and the film was not provided for the purpose of ensuring the adhesion to the rubber) were all in the comparative example. At least one of a corrosion state of corrosion and corrosion fatigue was not satisfied. For this reason, it cannot be said that any of the rubber-steel cord composites of the comparative examples can suppress deterioration of adhesion to rubber and corrosion fatigue by suppressing corrosion of steel wires and progress of corrosion.

Claims (5)

A rubber-steel cord composite in which a rubber coating layer is laminated on a steel cord surface via a coating for improving adhesion with the rubber coating layer, wherein the coating for improving adhesion is Cu. And further contains at least one element selected from the group consisting of Ni, Sn, and Zn, and the rubber coating layer has a content of 0.1 to 160.0 parts by mass based on 100 parts by mass of the rubber component. A rubber-steel cord composite, which is a rubber composition containing a water-soluble inorganic rust inhibitor.   The rubber-steel cord composite according to claim 1, wherein the thickness of the rubber coating layer containing the water-soluble rust inhibitor is 0.5 µm or more.   The rubber-steel cord composite according to claim 1 or 2, further comprising a rubber layer that does not contain a water-soluble rust inhibitor outside the rubber coating layer containing the water-soluble rust inhibitor. .   The rubber-steel cord composite according to any one of claims 1 to 3, wherein the steel cord is a steel wire having a tensile strength of 1000 MPa or more. The rubber-steel cord composite according to claim 4 , wherein the coating for improving the adhesion is brass plating.