JP2018119243A - Steel cord and rubber-steel cord composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel cord and a rubber-steel cord composite capable of further suppressing deterioration in adhesion to a rubber and corrosive fatigue.SOLUTION: The invention relates to a steel cord and a rubber-steel cord composite having a steel cord embedded in a rubber. The steel cord comprises a predetermined steel wire and a resin layer located on a surface of the steel wire. The resin layer contains a sparingly soluble rust preventive agent that is at least one selected from the group consisting of an inorganic compound, an organic compound and an organometallic compound and has a solubility to water at 25°C of 0.0001 g/l or more and less than 0.01 g/l in an amount of 0.1 mass % or more and 90 mass % or less based on the total mass of the resin layer.SELECTED DRAWING: None

Description

  The present invention relates to steel cords and rubber-steel cord composites.

  Generally, rubber products such as tires and conveyors are used by coating rubber on steel cords (plated steel cords) subjected to brass plating (copper-zinc alloy plating) for reinforcement. Causes of shortening the life of rubber products reinforced with these plated steel cords include corrosion of steel cords and corrosion fatigue caused by corrosion. Rubbers used for tires, conveyors and the like are permeable to water and oxygen, and various additives are used for rubber products in order to give the rubber the desired performance. Therefore, when water is contained in the rubber product, the steel cord for reinforcing the rubber product is exposed to a corrosive environment and corrodes.

  Further, corrosion may be promoted by scratching the rubber product due to various external and internal factors during use and facilitating the ingress of water. As a result, the rubber peels off from the steel cord due to corrosion or breaks earlier than the original fatigue life of the steel cord due to corrosion fatigue, so the life of the rubber product becomes shorter than the original fatigue life of the steel cord. There was a problem.

  As a technique for improving the fatigue characteristics by suppressing the decarburization of the wire against such problems and improving the corrosion resistance, Sn, Zn, and Bi are plated before the final heat treatment performed before the brass plating process. Techniques (for example, see Patent Document 1 below) and techniques for plating Ni (for example, see Patent Document 2 below) have been proposed.

  Further, as a technique for suppressing the corrosion of the wire rod, for example, a technology has been proposed in which at least one steel wire positioned inside the outermost layer strand of the wire rod is subjected to a metal having a higher ionization tendency than iron (for example, (See Patent Document 3 below.)

  In addition, a technique of applying Ni plating to improve the corrosion resistance of the steel cord and treating with a sulfur-containing silane coupling agent in order to ensure the adhesion thereof has been proposed (see, for example, Patent Document 4 below) .)

  In addition to the above technique, a technique for protecting the surface of the wire with a corrosion inhibitor made of a metal oxide, a rare earth metal salt, and an organic acid salt has been proposed (see, for example, Patent Document 5 below). .

Japanese Patent No. 5602657 JP 2012-167380 A JP-A-2015-196937 JP 2000-351852 A Japanese Patent No. 5649732

  However, although the techniques disclosed in Patent Document 1 and Patent Document 2 have contributed to the suppression of decarburization, the film is damaged by various external and internal factors particularly during the wire drawing process and in use. If it sticks, corrosion will occur like a conventional rubber product.

  Further, in the technique disclosed in Patent Document 3, the corrosion of the wire is suppressed while the metal having a high ionization tendency remains, but the metal having a high ionization tendency is easily corroded and consumed in a short period of time. Therefore, the durability improvement of rubber products was insufficient.

  In the technique disclosed in Patent Document 4, when the film is damaged due to various external and internal factors during use, corrosion occurs as in the case of conventional rubber products.

  Moreover, although the technique currently disclosed by the said patent document 5 contains organic acid salt, the means for hold | maintaining this organic acid salt is not mentioned. For this reason, with such a technique, the retention of the organic acid salt functioning as a rust inhibitor is weak, and the durability improvement of the rubber product has been insufficient.

  As mentioned above, with the conventional technology, there is a technology that suppresses corrosion, especially when there is a scratch on the plating layer, and suppresses the progress of corrosion and sufficiently suppresses the peeling of rubber from the steel cord and corrosion fatigue. I didn't.

  Then, this invention is made | formed in view of the said problem, The place made into the objective of this invention is the steel cord and rubber | gum which can suppress adhesiveness deterioration with rubber | gum, and corrosion fatigue more. It is to provide a steel cord composite.

  In order to further suppress adhesion deterioration with rubber and corrosion fatigue, it is important to suppress the corrosion of steel and the progress of corrosion. Therefore, the present inventors have investigated in detail the corrosion of brass-plated steel cords, which are typical examples of steel cords covered with rubber. As a result, the steel begins to preferentially corrode from the missing portion of the brass plating, which is a precious film applied to the steel cord, and the pitting corrosion of the steel proceeds in the lower layer of the precious plating layer as the corrosion proceeds, It was discovered that rust expansion and destruction caused peeling of a coating layer such as brass plating that functions as an adhesion layer with rubber. At the same time, the present inventors have found that corrosion fatigue progresses starting from a pitting corrosion site and leads to early fracture.

Based on these findings, the present inventors consider that it is effective to suppress the progress of corrosion in exposed steel parts such as brass plating defects, and as a result of further intensive studies, the results show that the surface of the steel cord is hardly soluble. The knowledge that the progress of corrosion of steel can be suppressed by forming a resin layer containing a rusting agent was obtained.
The gist of the present invention completed based on such findings is as follows.

[1] A predetermined steel wire and a resin layer positioned on the surface of the steel wire, and the resin layer is at least one selected from the group consisting of an inorganic compound, an organic compound, and an organometallic compound And the slightly soluble rust preventive agent whose solubility in water at 25 ° C. is 0.0001 g / l or more and less than 0.01 g / l is 0.1% by mass or more and 90% by mass with respect to the total mass of the resin layer. Steel cord containing:
[2] The steel cord according to [1], wherein the resin layer has a thickness of 0.01 μm or more.
[3] The steel cord according to [1] or [2], wherein the steel wire is a steel wire having a tensile strength of 1000 MPa or more.
[4] A plating layer is further provided between the steel wire and the resin layer, and the plating layer is made of an element selected from the group consisting of Zn, Ni, Cu, Sn, Fe, Cr, Al, and Mg. The steel cord according to any one of [1] to [3], containing at least one of them.
[5] A rubber-steel cord composite in which the steel cord according to any one of [1] to [4] is embedded in rubber.

  As described above, according to the present invention, it is possible to further suppress deterioration in adhesion to rubber and corrosion fatigue.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In addition, embodiment shown below does not limit this invention. The constituent elements of the embodiment include those that can be easily replaced by a person skilled in the art or those that are substantially the same. Furthermore, various forms included in the following embodiments can be arbitrarily combined within a range obvious to those skilled in the art.

  An embodiment of the present invention described in detail below relates to a steel cord embedded in a rubber product for the purpose of reinforcing various rubber products, and a composite of the steel cord and rubber. The present invention relates to a steel cord and a rubber-steel cord composite capable of suppressing deterioration of adhesion between rubber and a steel cord and corrosion fatigue by suppressing the corrosion and progress of corrosion.

(About steel cord and rubber-steel cord composite)
Hereinafter, the steel cord and the rubber-steel cord composite according to the embodiment of the present invention will be described in detail.

  The rubber-steel cord composite according to the present embodiment has a predetermined rubber composition and a steel cord embedded in the rubber composition.

<About steel cord>
Hereinafter, first, the steel cord embedded in a predetermined rubber composition in the rubber-steel cord composite according to the present embodiment will be described in detail.

[About resin layer]
The steel cord according to the present embodiment has a predetermined steel wire and a resin layer provided on the surface of the steel wire. Such a resin layer contains one or more hardly soluble rust preventives selected from the group consisting of inorganic compounds, organic compounds, and organometallic compounds. The content of the hardly soluble rust preventive is 0.1% by mass or more and 90% by mass or less. Here, content of a hardly soluble rust preventive agent is represented as a mass of a hardly soluble rust preventive agent when the sum total of the mass of the whole resin layer is set to 100.

  Examples of such hardly soluble rust preventives include phosphoric acid compounds (for example, phosphoric acid, primary phosphate, secondary phosphate, tertiary phosphate, pyrophosphoric acid, pyrophosphate, tripolyphosphoric acid, tripolyphosphoric acid. Condensed phosphates such as salts, phosphorous acid, phosphites, hypophosphorous acid, hypophosphites, etc.), vanadium compounds (e.g., vanadium oxides, hydroxides, sulfides, sulfates, Carbonates, halides, nitrides, fluorides, carbides, cyanides (thiocyanides) and their salts), niobium compounds, zirconium compounds, phosphates (eg, zinc phosphate, aluminum dihydrogen phosphate, Zinc phosphate, etc.), molybdate, phosphomolybdate (eg, aluminum phosphomolybdate), vanadate, etc., organic phosphoric acid and its salts (eg, phytic acid, phytin) Salts, phosphonic acids, phosphonates and their metal salts, such as alkali metal salts) of a available indicates a poorly soluble. Moreover, it is also possible to use what mixed 1 type (s) or 2 or more types among these compounds as this hardly soluble rust preventive agent. Here, in the present embodiment, the hardly soluble means that the solubility in water at 25 ° C. is included in the range of 0.0001 g / l or more and less than 0.01 g / l as described below.

  Examples of the resin component constituting the resin layer include an epoxy resin, a urethane resin, a polyester resin, a phenol resin, a polyether sulfone resin, a melamine alkyd resin, an acrylic resin, a polyamide resin, and a polyimide. Resin, silicone resin, polyvinyl acetate resin, polyolefin resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, natural rubber resin, synthetic rubber resin and the like can be used. At this time, in order to improve the adhesion to the metal, a silanol group or the like may be introduced into the various resins. In forming the resin layer, these resins may be used alone, a mixture of these resins may be used, or a laminated structure of these resins may be used. When these resin components function as a binder, the resin layer according to the present embodiment can more effectively retain the hardly soluble rust preventive agent as described above. As a result, in the present embodiment, the durability of the steel cord and the rubber-steel cord composite can be further improved.

  As a rust preventive agent that can be contained in the resin layer according to the present embodiment, a water-soluble rust preventive agent having a water solubility at 25 ° C. of 0.01 g / l or more and a water solubility at 25 ° C. Two types are considered: a poorly soluble rust preventive that is less than 0.01 g / l. The water-soluble rust inhibitor penetrates into the steel cord or rubber-steel cord composite and dissolves in the water that reaches the steel wire, and the steel cord component and the steel cord and the resin layer containing the water-soluble rust inhibitor are mixed. Bonded with the components of the layer provided between them and the exposed steel portion of the steel cord surface, a dense and poorly soluble film with good adhesion is formed on the exposed steel surface. This dense and poorly soluble coating with good adhesion is considered to be a barrier against corrosion factors to suppress corrosion and to suppress a decrease in fatigue limit due to corrosion. However, depending on the amount of infiltrated water and the period of exposure to the corrosive environment, all the water-soluble rust preventive agent may be eluted and the effect may be lost.

  Therefore, in the resin layer according to the present embodiment, a hardly soluble rust inhibitor having a solubility in water at 25 ° C. of less than 0.01 g / l is used as the rust inhibitor. The poorly soluble rust preventive agent remains in the resin layer regardless of the amount of infiltrated water and the period of exposure to the corrosive environment. The rust effect can be exhibited. Further, the steel cord and rubber-steel cord composite according to this embodiment in which a hardly soluble rust preventive agent is contained in the resin layer include a steel cord and a rubber-steel cord composite containing a water-soluble rust preventive agent. In comparison, the rust prevention effect can be exhibited even in a severer corrosive environment.

  As briefly mentioned above, the solubility of such a hardly soluble rust preventive in water at 25 ° C. is 0.0001 g / l or more and less than 0.01 g / l. Those having a solubility in water at 25 ° C. of 0.01 g / l or more are defined as water-soluble rust preventives in this embodiment. Such water-soluble rust preventives penetrate into steel cords or rubber-steel cord composites and dissolve in the water that reaches the steel wire, depending on the amount of infiltrated water and the period of exposure to the corrosive environment. It may be difficult to maintain a sufficient rust prevention effect. On the other hand, if the solubility in water at 25 ° C. is less than 0.0001 g / l, a sufficient amount of the rust preventive agent does not elute from the state of the compound, so that it is not suitable for practical use. In addition, the more preferable range of the solubility of a hardly soluble rust preventive agent is 0.0005 g / l or more and 0.005 g / l or less as solubility in water at 25 degreeC.

  In the steel cord according to the present embodiment, the content of the hardly soluble rust preventive contained in the resin layer is 0.1% by mass or more, so that a dense and good adhesion film is formed on the steel exposed portion of the steel cord surface. Can be formed. In addition, by making the total content of the hardly soluble rust inhibitor contained in the resin layer formed on the surface of the steel wire 0.5% by mass or more, the above effect can be achieved at a higher level, By setting the content to 1.0% by mass or more, the above effect can be achieved at an extremely high level.

  On the other hand, the hardly soluble rust preventive agent contained in the resin layer on the surface of the steel cord cannot be formed as a film when the total content exceeds 90% by mass. Therefore, the upper limit of the content of the hardly soluble rust preventive contained in the resin layer on the steel cord surface is set to 90% by mass. The content of the hardly soluble rust preventive agent contained in the resin layer is preferably 80% by mass or less.

  Thus, when exposed to a corrosive environment, the steel cord and the rubber-steel cord according to the present embodiment are formed on the surface of the steel cord in order to form a dense film having good adhesion and high barrier properties. In the composite, the resin layer provided on the surface of the steel wire and the type and amount of the rust inhibitor contained in the resin layer are limited to specific ones. As a result, according to the steel cord and the rubber-steel cord composite according to the present invention, it is possible to suppress both deterioration of adhesion with rubber and corrosion fatigue caused by corrosion.

  The resin layer as described above preferably has a thickness of 0.01 μm or more. In steel cords and rubber-steel cord composites, the thickness of the resin layer containing a sparingly soluble rust preventive agent is set to 0.01 μm or more, thereby suppressing deterioration in adhesion to rubber due to corrosion and corrosion. Suppression of fatigue can be achieved more effectively. In addition, although the upper limit of the thickness of a resin layer is not specifically limited, In order to aim at the saving of the above hardly soluble rust preventives, it is preferable to set it as 1000.0 micrometer (namely, 1 mm) or less. In addition, the range of the thickness of the resin layer containing the hardly soluble rust preventive is more preferably 0.1 μm or more and 10.0 μm or less. By making the thickness of the resin layer a more preferable range, the above effects can be enjoyed more stably.

  Note that the thickness and composition of these resin layers after being embedded in rubber were prepared by using a means such as Cryo-CP (Cross-section Polishing) to prevent the resin layer from being damaged, and making a FE-SEM-EDX ( Measurement can be performed by elemental analysis using a field emission scanning electron microscope with an energy dispersive X-ray analyzer or an FE-EPMA (field emission electron microanalyzer). In this measurement, the thickness of the resin layer is a value obtained by measuring the thickness of the thickest portion on the circumference of the obtained cross section. The content of the rust inhibitor contained in the resin layer is within the scope of the present invention as long as the elements other than C, O, and N are 0.1% by mass or more and 90% by mass or less with respect to C by elemental analysis. It is considered.

[About steel wire]
It is preferable to use a steel material having a tensile strength of 1000 MPa or more, and more preferable to use a steel material having a tensile strength of 2800 MPa or more for the steel wire as the material of the steel cord according to the present embodiment. If the tensile strength is 1000 MPa, the steel wire can be preferably used as a reinforcing material that reinforces rubber such as the tires and conveyors described above. In addition, the upper limit of the tensile strength of the steel wire used as a raw material is not specifically limited, The higher the better. Here, the tensile strength of the steel wire can be measured by a tensile test based on JIS Z2241 (1998).

  Examples of the steel wire having the above-described tensile strength can include a high carbon steel wire having a carbon content of 0.7 mass% or more. The wire diameter of the steel wire is not particularly limited, but is, for example, about φ (diameter) 0.05 mm to 0.4 mm.

<About rubber composition>
Next, the rubber composition in which the steel cord as described above is embedded in the rubber-steel cord composite according to the present embodiment will be briefly described.
The rubber composition in which the steel cord according to the present embodiment is embedded is not particularly limited. For example, generally known natural rubber or synthetic rubber is used alone or in combination of two or more. be able to. Synthetic rubbers include, for example, 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, chlorosulphonated polyethylene, acrylic rubber. For example, olefin rubber such as urethane rubber, fluorine rubber, polysulfide rubber, and the like can be used.

  Moreover, in the rubber composition according to the present embodiment, a compounding agent that is usually used in the rubber industry in order to improve and adjust the performance of the rubber can be appropriately blended in a normal compounding amount. Specifically, the compounding agents include fillers such as carbon black and silica, softeners such as aroma oil, guanidines such as diphenylguanidine, thiazoles such as mercaptobenzothiazole, N, N′-dicyclohexyl- Vulcanization accelerators such as sulfenamides such as 2-benzothiazolylsulfenamide, thiurams such as tetramethylthiuram disulfide, vulcanization accelerators such as zinc oxide, poly (2,2,4-trimethyl- 1,2-dihydroquinoline) and amines such as phenyl-α-naphthylamine. Even if these compounding agents usually used in the rubber industry coexist in the rubber composition, the performance of the present application is not affected.

<Other configurations>
In the steel cord and rubber-steel cord composite according to the present embodiment, a coating layer for improving corrosion resistance and wire drawing work or a steel wire is difficult between the steel wire as the material and the resin layer. There may be a film layer or the like for improving the adhesion with the resin layer containing a soluble rust preventive.

  The coating layer as described above is not particularly limited as long as it is a coating layer having desired characteristics. For example, the coating layer is selected from the group consisting of Zn, Ni, Cu, Sn, Fe, Cr, Al, and Mg. A film containing at least one of the above elements (in other words, a film layer containing the above element alone or a film layer containing an alloy composed of two or more of the above elements). it can. Such a coating layer can be formed by, for example, various plating methods using the above elements. Further, the method for forming the coating layer is not limited to the plating method as described above, and can be formed by applying other known means.

  Further, if particularly necessary, two or more kinds of the above-mentioned films can be combined and applied as a multilayer coating film.

  In addition, about the thickness of the above coating layers, although it does not specifically limit, For example, it is preferable to set it as the average thickness of about 50 nm-1000 nm. The average thickness of the coating layer can be measured in the same manner as the thickness of the resin layer.

  As described above, in the steel cord and the rubber-steel cord composite according to the present embodiment, hardly soluble on the surface of the steel wire as a raw material, which dissolves slightly and reacts with the metal to form a dense film. A resin layer containing a rust inhibitor is formed. As a result, in the steel cord and rubber-steel cord composite according to the present embodiment, in the corrosive environment, the slightly soluble rust preventive agent is slightly dissolved in the water present to form a defective portion on the surface of the steel cord. Reach and form a dense film with good adhesion. This dense film serves as a barrier against corrosion factors, and can effectively suppress the progress of corrosion of steel, suppress the peeling of rubber, and suppress pitting corrosion. As a result, in the steel cord and the rubber-steel cord composite according to the present embodiment, it is possible to suppress the deterioration of the adhesion between the metal and the rubber and the corrosion fatigue.

(About manufacturing method of steel cord and rubber-steel cord composite)
Next, a method for producing the steel cord and rubber-steel cord composite as described above will be briefly described.

  First, a final heat treatment is performed on a rolled or drawn steel wire to obtain a uniform and fine pearlite structure. Thereafter, the steel wire after heat treatment is pickled to remove the scale on the surface of the steel wire. Subsequently, the final wire drawing is performed in a wet manner to obtain a steel wire having a desired wire diameter and strength. At this time, for example, hydrochloric acid or sulfuric acid can be used as the acid solution used for pickling.

  A resin layer containing at least a sparingly soluble rust preventive agent is formed on the lubricant removed from the steel wire after the final wire drawing by degreasing treatment. Such a resin layer is formed by applying and drying an aqueous solution or solvent in which a sparingly soluble rust inhibitor and a resin monomer, resin oligomer, resin, or the like are dispersed on the surface of the steel wire.

  In addition, the treatment liquid used for forming the resin layer uses a hardly soluble rust preventive as described above, and the mass of the hardly soluble rust preventive is 0.1% by mass with respect to the total solid content of the treatment liquid. It adjusts so that it may become 90 mass% or less above.

  Here, the formation method of the resin layer is not particularly limited, and a known method can be used, and an immersion pulling method, a spray method, or the like can be applied. From the viewpoint of controlling the thickness of the resin layer to be formed, it is more preferable to use the immersion pulling method. Further, from the viewpoint of controlling the thickness of the resin layer, the viscosity of the treatment liquid in which at least the hardly soluble rust preventive and the resin are dispersed is preferably 0.5 mPa · s to 200 mPa · s at 25 ° C. .

  After a desired amount of a treatment liquid in which a hardly soluble rust preventive and a resin are dispersed is applied to the surface of the steel wire, the resin layer is formed by drying. At this time, it is more preferable to leave a part of the reaction terminal without completely polymerizing the resin layer or to include a component that improves the adhesion to rubber. Note that the drying conditions of the treatment liquid are not particularly limited, and the heating temperature and the heating time may be appropriately determined according to the solvent used in the treatment liquid.

  After forming the resin layer as described above, a steel cord is formed by twisting a plurality of obtained steel wires. The rubber-steel cord according to this embodiment in which a steel cord provided with a resin layer containing a hardly soluble rust preventive agent is embedded in the rubber by coating the steel composition with a known method on the steel cord. Form a complex.

  In order to improve the strength of the rubber composition, it is preferable that the rubber-steel cord composite is subjected to a vulcanization treatment at a temperature of 170 ° C. to 220 ° C. for several minutes to several hours following the above-described steps. . As the vulcanizing agent used for the vulcanization treatment, known ones can be used. For example, sulfur and its related elements (Se, Te), sulfur-containing organic compounds, organic peroxides, metal oxides (MgO, PbO, ZnO, etc.), organic polyvalent amines, modified phenolic resins, isocyanates and the like can be used. Also, during the vulcanization treatment, a vulcanization accelerator is added in addition to the vulcanizing agent for the purpose of shortening the vulcanization time, lowering the vulcanization temperature, reducing the amount of vulcanizing agent, and improving the quality of rubber products. May be.

  The resin layer containing the hardly soluble rust preventive agent may be applied by a stranded wire process, and the treatment liquid for forming the resin layer is dried together with the vulcanization process in the above vulcanization process. May be.

  Also, between the final heat treatment and after the final wire drawing, a coating layer for improving the corrosion resistance and wire drawing workability on the surface of the steel wire, and a resin layer containing the steel wire and a hardly soluble rust preventive agent You may provide the process of forming the membrane | film | coat layer for improving adhesiveness. The formation method of a film layer is not specifically limited, A well-known method can be used.

  For example, a Zn film, Ni film, Cu film, Sn film, Fe film, Cr film and alloy films thereof can be formed by an electroplating method, etc., and a Zn film, an Al film, a Mg film, These alloy films can be formed by a hot dipping method or the like. Moreover, it can utilize without being specifically limited about the film forming method by application | coating, For example, the immersion method, the spray method, etc. can be applied. In any case, it is preferable to subject the steel wire to degreasing and acid activation prior to the film formation treatment.

  As described above, according to the manufacturing method according to the present embodiment, the steel cord and the rubber that can suppress the corrosion of the steel cord and the progress of the corrosion, and can suppress the adhesion deterioration with the rubber and the corrosion fatigue can be suppressed. A steel cord composite can be obtained.

  Below, the effect of this invention is demonstrated concretely with an invention example. The present invention is not limited to the conditions used in the following invention examples. Moreover, the underlined part in Table 1 means that it deviates from the scope of the present invention.

  Steel containing, by mass%, C: 0.82%, Si: 0.21%, Mn: 0.42%, P: 0.007%, S: 0.006%, the balance being Fe and impurities Was melted and rolled into a steel wire having a diameter of 5.5 mm. The obtained steel wire was pickled and scale was removed, followed by drawing to a wire diameter of 1.8 mm. As a final heat treatment, this steel wire was austenitized by heating at 950 ° C. for 2 minutes in a heating furnace, then rapidly cooled to 600 ° C. at a cooling rate of 100 ° C./s, and held at that temperature for 10 seconds.

  The obtained steel wire was continuously subjected to electrolytic degreasing with an alkaline solution and electrolytic pickling with sulfuric acid, and then the plating shown in Table 1 below was performed.

  In Table 1 below, the Cu—Zn (brass plating) film is formed by subjecting the pyrophosphate Cu plating and the zinc sulfate plating so that the average thickness after wire drawing is 230 nm and the Cu concentration is 63 mass%. After performing in order, it formed by performing the alloying process which heats to 500 degreeC and hold | maintains for 4 second. Moreover, Cu film | membrane and Zn film | membrane were formed by performing pyrophosphoric acid Cu plating or Zn sulfate plating so that the average thickness after a wire-drawing process might be set to 230 nm, respectively. In Zn-Al plating and Zn-Al-Mg plating, a steel wire heated to a temperature about 10 ° C. higher than the melting point of the plating bath in an inert atmosphere is applied to a plating bath in which metals corresponding to the respective compositions are melted. It was formed by dipping and pulling up.

  Thereafter, wire drawing was performed by wet drawing using a wet lubricant so that the wire diameter became 0.2 mm, and a steel wire having a tensile strength of 3100 MPa was manufactured.

  When forming a film other than a Cu-Zn film, a Cu film, a Zn film, a Zn-Al film, or a Zn-Al-Mg film, the wire diameter is reduced by wet drawing using a wet lubricant. A desired film was formed after wire drawing to 0.2 mm.

  The Cu-Sn film is formed into an alloy that is heated to 400 ° C. and held for 4 seconds after sequentially performing Cu pyrophosphate plating and Sn Sn plating so that the average thickness is 230 nm and the Cu concentration is 80% by mass. Processed to form. The Cu—Ni coating is formed into an alloy that is heated to 800 ° C. and held for 5 minutes after sequentially performing Cu pyrophosphate plating and Ni sulfate plating so that the average thickness is 230 nm and the Cu concentration is 80% by mass. Processed to form. The Cr film was plated using a Sargent bath, the Ni film using a Watt bath, and the Sn film using a sulfuric acid bath so that the average thickness was 230 nm. In the Zn—Fe and Zn—Ni plating, the bath composition and the current density were adjusted from a sulfuric acid bath so as to obtain a desired composition, and the average thickness was 230 nm.

  In addition, the plating composition and the plating thickness were specified by collecting a sample from the plated steel wire and observing and measuring the cross-sectional sample produced by the cryo-CP using FE-SEM-EDX.

The resin layer containing the hardly soluble rust preventive shown in the following Table 1 was formed to the obtained steel wire.
Specifically, a treatment liquid in which a resin component and a hardly soluble rust preventive were dispersed in a solvent or water with the composition shown in Table 1 was prepared. Then, the steel wire was immersed in these treatment liquids, the pulling speed was adjusted so that the thickness shown in Table 1 was obtained after drying, and the treatment liquid was applied to the surface of the steel wires. The coated steel wire was placed in a furnace maintained at 250 ° C., held for 1 minute to 5 minutes until the temperature reached by the steel wire reached 210 ° C., and then taken out and cooled.

  In addition, the thickness and composition of the resin layer containing a hardly soluble rust preventive agent were measured with a FE-SEM-EDX for a cross-sectional sample prepared by cryo-CP by collecting a sample from a steel wire coated and dried with a resin layer. did.

  Four steel wires thus obtained were twisted at a pitch of 5 mm to form a steel cord, set in a mold, embedded in the rubber composition shown in Table 2, and heated at 160 ° C. for 30 minutes. A vulcanization treatment was performed by a press to prepare a sample for evaluation.

  For each sample for evaluation, prepare in the center of the sample a notch with a cutter so that the plated steel wire is exposed in a direction perpendicular to the steel wire. Adhesion after deterioration and pitting corrosion The presence or absence was evaluated.

  The adhesion after deterioration was evaluated by measuring the adhesive strength before and after the deterioration treatment and comparing the adhesive strength before and after the deterioration treatment. Specifically, when the strength before the deterioration treatment is set to 100, the strength after the deterioration treatment is evaluated as C, the strength from 50 to less than 70 is evaluated as B, and 70 or more. This was evaluated as A, and a score of B or higher was accepted. The adhesive strength was evaluated by measuring the pulling force when the steel cord was pulled out from the rubber using a tensile test apparatus and evaluating the maximum pulling force. In addition, the deterioration treatment was performed by holding for 300 hours in a constant temperature and humidity chamber having a relative humidity of 95% and a temperature of 80 ° C.

  As for the presence or absence of pitting corrosion, samples were taken from the drawn steel wire for each sample after deterioration treatment, and the corrosion shape of the steel cord was measured with FE-SEM-EDX for the cross-section sample prepared with cryo-CP. confirmed. Specifically, when the depth of pitting corrosion is 1 μm or more, it is evaluated as C, when it is less than 1 μm, it is evaluated as B, when it is less than 0.5 μm, it is evaluated as A, and a score B or more is evaluated. Passed.

  Corrosion fatigue was evaluated by immersing the obtained steel cord in a 20% 0.1% NaCl aqueous solution in a stress load type rotating bending fatigue test and conducting a corrosion fatigue test at a rotation speed of 3000 rpm. . Evaluation of corrosion fatigue was expressed as an index when the number of rotations until the fracture of the brass-plated steel wire without a resin layer containing a sparingly soluble rust preventive was regarded as the lifetime and the lifetime (Comparative Example 1) was 100. . Specifically, an index of 100 or less was evaluated as C, an index of 101 to 129 was evaluated as B, an index of 130 or more was evaluated as A, and a score of B or more was regarded as acceptable.

  The results obtained by the above evaluation are summarized in Table 1 below.

In Table 1 below, details of the compounds used are as follows.
Epoxy resin: manufactured by ADEKA Corporation, trade name: Adeka Resin EM-0461N
Natural rubber-based resin: manufactured by JSR, trade name: RSS # 3
Urethane resin: manufactured by ADEKA Corporation, trade name: HUX-232
Phenol resin: manufactured by DIC Corporation, trade name: IF-1200
Acrylic resin: DIC Corporation, trade name: A-801
Synthetic rubber: Nippon Zeon Co., Ltd., trade name: Nippon 1562
Titanium (IV) oxide: General reagent Calcium carbonate: General reagent Zirconium carbonate: General reagent Fluorotitanic acid: General reagent Zirconium hydroxide: General reagent Zirconium carbonate: General reagent

  According to Table 1 above, the examples corresponding to the present invention show good results in all results, including adhesion after deterioration, pitting corrosion state, and corrosion fatigue. there were. Therefore, for the steel cord and rubber-steel cord composite according to the present invention, it was possible to suppress adhesion deterioration and corrosion fatigue with rubber by suppressing the progress of corrosion and corrosion of the steel cord, It can be said.

  On the other hand, the comparative examples not corresponding to the present invention did not satisfy at least one of adhesion after deterioration, pitting corrosion state, and corrosion fatigue in any result. For this reason, none of the rubber-steel cord composites of the comparative examples could suppress adhesion deterioration with the rubber and corrosion fatigue by suppressing the progress of corrosion and corrosion of the steel cord. I understand that.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to this example. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

Claims (5)

A predetermined steel wire;
A resin layer located on the surface of the steel wire;
With
The resin layer is at least one selected from the group consisting of inorganic compounds, organic compounds and organometallic compounds, and has a solubility in water at 25 ° C. of 0.0001 g / l or more and less than 0.01 g / l. A steel cord containing a slightly soluble rust preventive agent in an amount of 0.1% by mass to 90% by mass with respect to the total mass of the resin layer.   The steel cord according to claim 1 whose thickness of said resin layer is 0.01 micrometer or more.   The steel cord according to claim 1 or 2, wherein the steel wire is a steel wire having a tensile strength of 1000 MPa or more. A plating layer is further provided between the steel wire and the resin layer,
The said plating layer contains at least 1 sort (s) among the elements selected from the group which consists of Zn, Ni, Cu, Sn, Fe, Cr, Al, and Mg of any one of Claims 1-3. Steel cord. A rubber-steel cord composite in which the steel cord according to any one of claims 1 to 4 is embedded in rubber.