JP2008240140A - Steel wire for reinforcing rubber product excellent in corrosion fatigue resistance and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel wire for reinforcing a rubber product having excellent corrosion fatigue resistance even after being embedded in a rubber composition and capable of maintaining the shape and strength of a rubber product even in a corrosive environment, and its manufacturing method. <P>SOLUTION: The steel wire for reinforcing a rubber product excellent in corrosion resistance includes: a plating layer containing 55-75% Cu on a surface of a steel wire having a diameter of 0.1-0.4 mm; and further, a compound coating layer, in which the main components are oxygen and metal containing one or more kinds among Zr, Ti, Si, Mo, Co, and Ni, formed on the plating layer, wherein the thickness of the coating layer is 10-1,000 nm. The steel wire can be manufactured by forming a metal oxide coating film on the plating layer of the steel wire by performing continuous deposition processing by forcible energizing at a current density of 1-10 A/dm<SP>2</SP>by a liquid phase deposition method using a metal fluoride complex. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steel wire for reinforcing a rubber product, which is used for reinforcing a rubber product and excellent in corrosion fatigue resistance, and a method for producing the same.

  Conventionally, steel strands have been widely used as reinforcing materials for rubber products such as tires, belts and hoses. Such a steel wire embedded in the rubber product is continuously subjected to an external force during use. Furthermore, since moisture and air permeate and penetrate through the rubber composition, the surface of the steel strand is exposed to a corrosive environment. Therefore, since stress acts on the steel wire in a corrosive environment, it breaks due to corrosion fatigue, thereby reducing the strength of the rubber product.

  Therefore, the steel wire embedded in the rubber composition needs to have an improved durability life as well as a high breaking strength, and is required to improve corrosion fatigue resistance. As a conventional technique for improving the corrosion fatigue resistance of steel wires and steel cords for reinforcing rubber products, a technique has been proposed in which La and Ce are added to the steel material to improve the corrosion fatigue resistance of the steel material itself (for example, patents). Reference 1). Further, as a method by surface treatment, a technique for performing an organic film treatment on the surface of a steel wire (for example, see Patent Document 2) and a technique for limiting pinhole defects in a plating film on the surface (for example, see Patent Document 3) are proposed. Has been. Furthermore, a method of applying compressive residual stress to the surface portion of the steel cord strand and applying a lubricating oil has also been proposed (see, for example, Patent Document 4). However, in these conventional techniques, a sufficient effect of improving the corrosion-resistant fatigue life of the steel wire for reinforcing rubber products has not been obtained.

JP-A-8-170149 JP-A-6-49786 JP-A-8-199394 Japanese Patent Laid-Open No. 5-86589

  The present invention has been made in view of the above-described problems, and aims to ensure the strength and durability of rubber products, and the steel wire for reinforcing rubber products excellent in corrosion fatigue resistance and the production thereof. A method is provided.

  Assuming a corrosive environment in which moisture and oxygen have penetrated into the rubber product, the present inventors have shown the corrosion fatigue resistance characteristics of steel wires for reinforcing rubber products on which various organic coatings and inorganic coatings are formed. The composition and thickness were changed for evaluation. As a result, it was clarified that the corrosion fatigue resistance of steel wires for reinforcing rubber products is remarkably improved by forming an inorganic coating composed of a compound mainly composed of metal and oxygen with a certain thickness on the surface. Furthermore, it has been found that by embedding a reinforcing material with improved corrosion fatigue resistance in rubber, the shape and strength of the rubber product can be maintained and the durability life can be improved. This invention is made | formed based on such knowledge, The summary is as follows. Note that the number of wires that pass through the film forming process is not limited to one, and a plurality of wires can be processed simultaneously.

  (1) It has a plating layer on the surface of a steel strand having a diameter of 0.1 to 0.4 mm, and further, one or two of Zr, Ti, Si, Mo, Co, Ni on the surface of the plating layer A steel wire for reinforcing rubber products having excellent corrosion fatigue resistance, comprising a coating layer having a thickness of 10 nm or more and 1000 nm or less composed of a compound containing at least a seed and oxygen as a main component.

  (2) The steel wire for reinforcing rubber products according to (1) above, wherein the plating layer contains 55 to 75% by mass of Cu.

  (3) The coating layer is one or both of a metal oxide and a metal hydroxide, and the ratio of the metal species to the total of metal species and oxygen in the coating layer is 30% to 70% in atomic%. (1) or (2), wherein the steel wire for reinforcing rubber products is excellent in corrosion fatigue resistance.

  (4) The steel strand according to any one of (1) to (3) above is in mass%, C: 0.4 to 1.1%, Si: 0.2 to 1.5%, Corrosion-resistant fatigue characterized by containing Mn: 0.2-1.0%, P: 0.02% or less, S: 0.02% or less, the balance being Fe and inevitable impurities Steel wire for reinforcing rubber products with excellent characteristics.

  (5) The steel strand is further mass%, Cr: 0.05 to 0.5%, Cu: 0.05 to 0.3%, Ni: 0.05 to 0.5%, Mo: 0 0.05 to 0.3%, V: 0.05 to 0.5%, W: 0.05 to 0.3%, Co: 0.01 to 0.1%, or one or more The steel wire for reinforcing rubber products having excellent corrosion fatigue resistance as described in (4) above.

  (6) A rubber product excellent in corrosion fatigue resistance, characterized in that it is a stranded wire formed by twisting a plurality of steel wires for reinforcing rubber products according to any one of (1) to (5) above. Stranded steel wire for reinforcement.

  (7) A method for manufacturing a steel wire for reinforcing rubber products according to any one of (1) to (3) above, wherein a metal fluoride complex is formed on the surface of the plating layer provided on the surface of the steel wire. Excellent in anti-corrosion fatigue characteristics characterized by forming a compound mainly composed of oxygen and one or more of Zr, Ti, Si, Mo, Co, Ni by a liquid phase precipitation method using A method of manufacturing steel wires for reinforcing rubber products.

  (8) The method for producing a steel wire for reinforcing a rubber product according to (7), wherein the steel wire has the component composition as described in (4) or (5) above and has excellent corrosion fatigue resistance characteristics .

(9) The anode is immersed in the metal fluoride complex solution, and the steel strand having a plating layer on the surface is used as the cathode to continuously pass through the metal fluoride complex solution, and the current density is 1 to 10 A / dm ^2. The rubber having excellent corrosion fatigue resistance as described in (7) or (8) above, which comprises a step of forming a film in the range of, and a step of subsequently drying in a temperature range of 80 ° C. to 200 ° C. Manufacturing method of steel wire for product reinforcement.

  With the coating layer of the present invention, it is possible to provide a steel wire for reinforcing rubber products that has excellent corrosion fatigue resistance even in an environment embedded in a rubber composition and can maintain the shape and strength of the rubber product. It becomes. Moreover, according to the liquid phase precipitation method using the metal fluoride complex of the present invention, it is possible to provide a method for producing a steel wire for reinforcing rubber products having a coating layer, which can improve corrosion fatigue resistance. it can. Moreover, the stable wire drawing process is attained by making Cu content rate in a plating layer into 55 to 75%, and it can manufacture stably industrially. As described above, the industrial contribution of the present invention, which can provide a steel wire for reinforcing rubber products excellent in corrosion fatigue resistance and a method for producing the same, is extremely remarkable.

  The present inventors have studied in detail the improvement of the corrosion fatigue resistance of the steel wire for reinforcing rubber products inside the rubber composition. As a result, in a corrosive environment due to the intrusion of moisture and air into the rubber composition, the durability of the rubber product is improved by forming a coating layer on the surface of the steel wire for reinforcing the rubber product and improving the corrosion resistance. Revealed. Therefore, the present inventor has examined and succeeded in improving the corrosion resistance by forming a coating film having a high gas and moisture barrier property on the surface so that the steel wire is not oxidized by moisture and oxygen that have penetrated into the rubber. The proper condition of the form of the coating layer was found.

  FIG. 1 is a schematic cross-sectional view of a steel wire for reinforcing rubber products according to the present invention. The central portion is a steel wire 1, a plating layer 2 exists around it, and a coating layer 3 mainly composed of metal and oxygen is formed on the surface thereof with a thickness in the range of 10 to 1000 nm. Here, the main component of metal and oxygen means atomic%, and the ratio of metal species and oxygen is 60% or more of the whole compound.

  The strand of the present invention is manufactured by cold working. For example, when manufacturing by die drawing, if it becomes thinner than 0.1 mm, the number of processing steps increases, and the work becomes complicated and the productivity is greatly reduced. .1 mm was taken as the lower limit of the wire diameter. On the other hand, when the wire diameter is thicker than 0.4 mm, the strength of the wire is lowered, and the effect as a reinforcing material is reduced.

  The metal species contained in the coating layer formed on the surface of the plating layer provided on the surface of the steel strand of the present invention may be any one of Zr, Ti, Si, Mo, Co, and Ni. It may be a plurality of metal species. All of these metal species have the effect of improving the corrosion fatigue resistance. By making the metal species one or more of Zr, Ti, Si, Mo, Co, and Ni, reinforcement of rubber products The effect of improving the corrosion resistance of steel wires is clearly recognized. The mechanism by which these metal species improve the corrosion fatigue resistance of steel wires for reinforcing rubber products is because the metal species forms a strong chemical bond with the rubber formed on the coating layer. It is estimated that the improvement in corrosion fatigue resistance is remarkable when used as a reinforcing steel wire. From the viewpoint of strong chemical bonding with rubber, particularly preferred metal species are Zr and Ti. In addition, the metal species of the coating composed of oxides or hydroxides of these metal species can be identified by X-ray photoelectron spectroscopy (referred to as XPS), Auger electron spectroscopy (referred to as AES), and infrared spectroscopy. it can.

  The metal species constituting the coating layer and the compound containing oxygen as a main component means either an oxide of a metal species, a hydroxide, or a mixture of an oxide and a hydroxide. The reason why the coating layer contains the metal type hydroxide is that moisture contained in the oxide formed by the liquid phase deposition method may remain even after drying.

The thickness of the coating layer greatly affects the corrosion fatigue resistance of the steel wire for rubber product reinforcement. The thickness of the coating layer was changed, and the corrosion fatigue resistance characteristics were evaluated by a rotational bending fatigue test using the stress loading method shown in FIG. In the corrosion fatigue test, the tip of the curvature portion of the corrosion test plating wire (test piece) 4 was immersed in a corrosion test solution 5 of a 0.1% NaCl aqueous solution at a rotation speed of 3000 rpm. The corrosion fatigue life was evaluated by the number of rotations (life) until breakage with a load stress σ of 300 MPa. The load stress was determined by the following formula.
σ = 1.19 × d × E / C
L = 2.19 × C
Here, σ is the load stress (MPa), d is the wire diameter (mm) of the steel wire, E is the elastic modulus of the steel wire, and is 2.09 × 10 ⁵ MPa. C is the distance between chucks (mm), and L is the length of the test piece (mm).

  The results are shown in FIG. As is clear from the results of the relationship between the film thickness (nm) and the corrosion fatigue life (min) in FIG. 3, when the thickness of the coating layer is less than 10 nm, the effect of improving the corrosion fatigue resistance is insufficient. There is. On the other hand, when a film thicker than 1000 nm is formed, the effect of improving the corrosion fatigue resistance is saturated, and in some cases, the surface of the film may be cracked or peeled off, and the corrosion fatigue resistance may be lowered. Therefore, the thickness of the coating layer made of one or both of metal oxide and metal hydroxide is preferably 10 nm to 1000 nm. More preferably, it is 20-500 nm.

  Here, the thickness of the coating layer of the compound composed of the metal species and oxygen is analyzed by XPS or Auger electron spectroscopy (AES) from the surface of the steel wire for reinforcing rubber products, and the concentration distribution in the depth direction (depth) It can be evaluated by measuring a profile). That is, the depth from the surface where oxygen is present is the thickness of the coating layer.

  Further, the thickness of the steel wire, the plating layer, and the coating layer may be measured by observing the steel element wire, the plating layer, and the coating layer with a scanning electron microscope (referred to as SEM) or a transmission electron microscope. In this case, any of the following methods may be used. One is a method in which a focused ion beam (FIB) is used to cut perpendicularly to the length direction of the steel wire and the surface is observed by SEM. The other is a method in which a thin film sample including a coating layer is prepared and the structure is observed with a transmission electron microscope at a magnification of 3000 to 100000 times.

  As a method for forming a coating layer that is a compound containing a metal species and oxygen, there are a liquid phase method such as a sputtering method, a CVD gas phase method, and a sol-gel method. Among these, the vapor phase method has a problem that expensive equipment is required to form a vacuum environment. On the other hand, among the liquid phase methods, the sol-gel method requires baking after coating, and is therefore affected by the occurrence of cracks and the diffusion of metal from the material. Moreover, since it contains a volatile component, it is difficult to form a dense film.

  Therefore, in the present invention, the coating layer is formed by a liquid phase deposition method using a metal fluoride complex solution, which is one of the liquid phase methods. Thereby, a dense coating layer can be formed in a short time, and the thickness of the coating layer can be accurately controlled.

  Metal fluoride complexes include silicon fluorosilica complex, titanium fluoro complex, zircon fluoro complex, molybdenum fluoro complex, niobium fluoro complex, zinc fluoro complex, etc. An aqueous solution can be used as the treatment liquid.

  In the present invention, in order to form a coating layer on the surface of a steel wire continuously in a short time by a liquid phase deposition method, the anode is immersed in an aqueous metal fluoride complex solution, and the steel wire is used as a cathode. While passing, energize and process continuously. In order to improve productivity, it is preferable to run a plurality of steel strands simultaneously and control the current density and the wire speed, respectively.

When processing a plurality of steel strands at the same time, the current density per steel strand during energization is preferably 1 A / dm ² or more. When the current density is less than 1 A / dm ^2, the film formation rate of the coating layer is slow, and productivity may be impaired. On the other hand, when the current density is larger than 10 A / dm ^2, the thickness of the coating layer in the circumferential direction and the longitudinal direction of the steel element wire becomes non-uniform, and a portion where the coating is not locally formed may occur. Therefore, it is preferably in the range of current density per one steel wire of 1 to 10 A / dm ^2.

  Since the anode is required to have corrosion resistance, it is preferable to use an electrode in which a Ti plate is coated with iridium oxide or platinum.

  If the drying temperature is less than 80 ° C. after the formation of the coating layer, the generated coating layer may be insufficiently dried. As a result, when moisture remains in the coating layer, a coating layer made of a compound of a metal species and oxygen becomes difficult to be generated stably. On the other hand, when the drying temperature is higher than 200 ° C., the strength of the steel strand may be lowered. Therefore, the drying temperature is preferably in the range of 80 to 200 ° C.

  A plating layer may be provided on the surface of the steel wire. This plating layer is formed for the purpose of improving the lubricity for processing into a predetermined wire diameter and improving the corrosion resistance. The plating layer is preferably made of one or more of Cu, Zn, Sn, Co, and Ni.

  In particular, the plating layer preferably contains Cu. When the Cu concentration is 55% or less, the workability may be lowered in the step of cold working the steel wire to 0.1 to 0.4 mm. As a result, there is a tendency for many disconnections to occur, and the corrosion resistance of the plating layer may be reduced, so that the corrosion fatigue life is slightly reduced. On the other hand, even when the Cu concentration exceeds 75%, the stretchability during cold working may be reduced, and the drawability deteriorates, so that the drawing speed decreases, the die life decreases, and the occurrence of disconnection increases. It can be a cause. Furthermore, the cathodic reaction of the plating layer is promoted, the galvanic corrosion characteristics are slightly deteriorated, and the corrosion fatigue resistance characteristics are slightly lowered. Therefore, the Cu concentration in the plating layer is preferably 55 to 75%. More preferably, it is 60 to 70%.

  In addition, although the steel wire can be used as a rubber reinforcing wire by a single wire, high toughness can be obtained by twisting a plurality of wires to make a reinforcing body, and rubber can be effectively reinforced.

  The plating layer on the surface of the steel wire may be formed by a conventional method. If the plating layer has a composition containing Cu, manufacturing methods such as wet plating, dry plating, chemical vapor deposition (CVD), and physical vapor deposition (PVD) are applicable, and the method is not particularly limited. . Further, wet brass plating may be performed, and a method of brassing the layered plating layer by thermal diffusion by sequentially performing electric Cu plating and electric Zn plating may be employed. Further, when the plating layer has a composition containing Cu, the composition other than Cu is not particularly limited, and a composite component plating composition containing Zn, Co, Ni, or the like is applicable.

  Next, the components of the steel strand will be described. In addition,% is the mass%.

C: 0.4 to 1.1%
C is a component that has the greatest influence on the strength of the steel wire, and if it is less than 0.4%, sufficient strength as a steel wire for reinforcing rubber products may not be ensured. On the other hand, if it exceeds 1.1%, pro-eutectoid cementite is formed at the grain boundary, and cold workability may be lowered. Therefore, the C content is preferably 0.4 to 1.1%.

Si: 0.2 to 1.5%
Si is a steelmaking process for producing steel materials, and is added as a deoxidizing component and has an effect of improving strength by solid solution strengthening, and preferably contains 0.2% or more. On the other hand, if added over 1.5%, the steel material becomes brittle and the workability and heat treatment properties may be reduced. Further, if the scale generated on the surface remains on the surface of the steel wire, it may cause trouble during processing. Therefore, the Si amount is preferably 0.2 to 1.5%.

Mn: 0.2 to 1.0%
Similar to Si, Mn is added as a deoxidizing component in the steelmaking process, and has the effect of increasing strength. In order to obtain this effect, it is preferable to add 0.2% or more of Mn. On the other hand, Mn is an element that increases hardenability and easily segregates, and if added over 1.0%, a supercooled structure such as bainite is likely to be generated, the steel material becomes brittle, and workability is reduced. There is. Therefore, the Mn content is preferably 0.2 to 1.0%.

P and S: 0.02% or less P and S are impurity elements inevitably contained in the steel, and improve the workability of the steel wire by reducing it as much as possible. It is preferable to limit.

  Furthermore, in order to improve the corrosion fatigue resistance, one or more of Cr, Cu, Ni, W, Mo, and Co may be included.

Cr: 0.05-0.5%
Cr in the steel is an element that improves the corrosion resistance of the steel and has the effect of making the pearlite lamella fine and increasing the strength. In order to obtain this effect, it is preferable to add 0.05% or more of Cr. On the other hand, when Cr is added in excess of 0.5%, the scale peelability may be deteriorated, and since the transformation is delayed, a supercooled structure (bainite or martensite) is easily generated during heat treatment, and the workability is improved. May get worse. For this reason, it is preferable to make Cr addition amount 0.05-0.5%.

  Furthermore, since Cu, Ni, W, Mo, and Co are elements having an effect of improving the corrosion fatigue resistance, one kind or two or more kinds may be added. The effect of these elements not only improves the corrosion resistance of the steel material, but also exhibits a synergistic effect by forming the coating layer and adding it to the steel strand, and a greater effect of improving the corrosion resistance property can be obtained.

Cu: 0.05-0.3%
Cu has the effect of improving corrosion fatigue resistance by forming a dense and stable rust layer on the surface of the steel wire. In order to obtain this effect, addition of 0.05% or more is preferable, but if added over 0.3%, segregation occurs at the grain boundaries, and surface cracks are likely to occur during hot rolling, so 0.3% Is preferably the upper limit.

Ni: 0.05-0.5%
When Ni is dissolved in steel, it has an effect of improving the wire drawing workability and the toughness of the steel wire after processing. Further, when Ni is concentrated on the surface layer, there is an effect of improving the corrosion fatigue resistance. In order to obtain these effects, addition of 0.05% or more is necessary. However, if it exceeds 0.5%, the peelability of the scale may be deteriorated. Thereby, we are anxious about the fall of wire drawing workability. Moreover, since the effect of improving the corrosion fatigue resistance by surface concentration is saturated, it becomes economically unreasonable. From the above, the upper limit is preferably 0.5%.

Mo: 0.05-0.3%
Mo, like W, is an element that improves the pitting corrosion resistance by generating molybdate ions having a corrosion reaction suppressing action on the surface during corrosion dissolution. In order to obtain this effect, addition of 0.05% or more is preferable. However, if the addition exceeds 0.3%, the effect is saturated, so it is preferable to make 0.3% the upper limit.

V: 0.05-0.5%
V forms fine carbides and has the effect of increasing the strength by refining steel crystals and strengthening precipitation. In order to obtain this effect, addition of 0.05% or more is preferable. On the other hand, if added over 0.5%, the wire drawing workability may be deteriorated, so 0.5% is preferably the upper limit.

W: 0.05-0.3%
W, like Mo, is an element that improves the pitting corrosion resistance by generating tungstate ions having a corrosion reaction suppressing action on the surface during corrosion dissolution. In order to obtain this effect, addition of 0.05% or more is preferable. However, if added over 0.3%, the hot workability may be deteriorated, so 0.3% is preferable as the upper limit.

Co: 0.01 to 0.1%
Co also has the effect of improving corrosion fatigue resistance and improving wire drawing workability and stranded wire workability. To obtain these effects, addition of 0.01% or more is preferable. However, Co is an expensive element, and even if added in excess of 0.3%, the effect is saturated, so 0.3% is preferable as the upper limit.

  Although it does not specifically limit about another trace element, 0.05% or less of Al which is a deoxidizer as an inevitable impurity element, and 0.001% or less of Sn mixed from the raw material scrap may be contained.

  As described above, the particularly preferable embodiment of the present invention has been described in detail. The steel wire for reinforcing rubber products of the present invention obtained as described above has improved fatigue characteristics and can be stably produced. It can be suitably used as a reinforcing material for products such as tires, belts and hoses.

  Hereinafter, the present invention will be described in more detail with reference to examples, but aspects other than the diameter of the steel strand, the metal species contained in the coating layer, and the thickness of the coating layer, that is, the component composition and production of the steel strand. The method, the plating composition, and the conditions for forming the coating layer are not limited to the embodiments described below.

  A 5.5 mm hot rolled steel wire made of various steel components shown in Table 1 was used as a raw material. After removing the scale on the surface of the steel wire by pickling, dry drawing was performed and cold drawing was performed to 1.2 mm to obtain a steel strand. Thereafter, the mixture was heated to a temperature of 950 to 1000 ° C. and subjected to constant temperature transformation by a patenting treatment so that a uniform pearlite structure was obtained in the range of 550 to 630 ° C. Subsequently, electrolytic copper plating and electrolytic zinc plating or electrolytic tin plating were successively performed to obtain Cu—Zn or Cu—Sn plating. Further, in some embodiments, electric Co, or electric Ni or electric Mo plating is performed on the Zn plating to form a plating layer made of Cu—Zn—Co or Cu—Zn—Ni and Cu—Zn—Mo. Thus, the plating thickness provided on the surface of each steel wire was adjusted, and thermal plating treatment was performed at 580 ° C. for 10 s in a fluidized bed furnace to obtain brass plating. The Cu concentration and the plating thickness were changed depending on the thickness of the Cu plating and the thickness of the Zn plating.

  A steel wire provided with this brass plating on the surface was drawn to 0.08 to 0.45 mm by wet drawing to obtain a brass-plated steel wire (also referred to as a brass-plated wire). Furthermore, the film-forming process to these brass plating strands was performed by the liquid phase precipitation method. That is, the anode was immersed in a solution adjusted to have a pH of 3 to 4 using ammonium fluoride, hydrofluoric acid, and aqueous ammonium in a hexafluoro complex aqueous solution, a mixed aqueous solution of metal chloride and ammonium hydrogen fluoride, The film was formed by running in the liquid while energizing with the brass plating wire as the cathode.

  More specifically, a silicon oxide film is coated with 0.5 mol / l ammonium hexafluorosilicate aqueous solution, 0.1 mol / l ammonium hexafluorotitanate aqueous solution, 0.1 mol / l titanium chloride and 0.3 mol / l hydrogen fluoride. Titanium oxide film with mixed aqueous solution of ammonium, 0.01 mol / l ammonium hexafluorozirconate aqueous solution, 0.01 mol / l zirconia oxide film with 0.5 mol / l ammonium hexafluoromolybdate aqueous solution and molybdenum oxide film with 0 mol A nickel oxide film is mixed with a mixed aqueous solution of 1 mol / l nickel chloride and 0.3 mol / l ammonium hydrogen fluoride, and a cobalt oxide film is mixed with a mixed aqueous solution of 0.1 mol / l cobalt chloride and 0.3 mol / l ammonium hydrogen fluoride. A film was formed. In the case of the composite coating, the treatment was performed twice. As the anode, an electrode obtained by coating a iridium on a Ti plate was used. The thickness of the coating layer was adjusted by cathodic electrolysis using a brass-plated element wire as a cathode while changing the current density and the treatment time. Also, immediately after the film formation, a drying treatment is performed in a temperature range of 65 to 220 ° C., and a coating layer made of one or both of a metal oxide and a metal hydroxide is formed on the surface of the brass-plated element wire, and a rubber product A steel wire for reinforcement was obtained.

  The production state, components, and thickness of the compound composed of the metal species and oxygen of the coating layer formed on the surface of the brass plating wire were identified by X-ray photoelectron spectroscopy and infrared spectroscopy.

  The steel wire for reinforcing rubber products was immersed in a 0.1% NaCl aqueous solution by 20 mm at the tip of the curvature portion by a stress loading type rotating bending fatigue test shown in FIG. 2, and a corrosion fatigue resistance test was conducted at a rotational speed of 3000 rpm. The corrosion fatigue life was evaluated by the number of revolutions (life) until breakage with a load stress of 300 MPa.

  As a conventional material, a hot-rolled wire having the components shown in Table 1A is subjected to dry wire drawing, patenting treatment, and brass plating treatment in the same process as in the present invention, and further, steel that does not perform coating treatment on the plating surface layer by wet wire drawing. A strand was manufactured and the corrosion fatigue life was evaluated.

  As described in Table 2, No. 1 of the present invention. Corrosion fatigue life of steel wires for reinforcing rubber products of 1 to 33 is about 30 to 70% longer than that of steel wires for reinforcing rubber products of Comparative Examples 34 and 39 to 44 having no coating layer. I understand that

  No. which is a comparative example. No. 35 is an example in which the thickness of the coating layer is thinner than that of the present invention and there is almost no effect of improving the corrosion fatigue life. On the other hand, Comparative Example No. No. 36 is an example in which the thickness of the coating layer exceeds the upper limit of the present invention, and the corrosion fatigue resistance is deteriorated by cracking or peeling of the coating.

  Comparative Example No. in which the wire diameter of the steel strand is thinner than the range of the present invention. No. 37 is an example in which the degree of wire drawing is large and the corrosion resistance deteriorates due to an increase in specific surface area. On the other hand, Comparative Example No. No. 38 is an example in which the diameter of the steel wire is large, the strength is low, and the corrosion fatigue life is reduced.

  No. Reference numerals 39 to 41 are comparative examples in which no coating layer is formed, and the corrosion fatigue life is remarkably reduced. Moreover, these are less than the minimum of the range with preferable C, Si, and Mn, the intensity | strength after wire drawing falls a little, and has a bad influence on corrosion fatigue life.

  No. 42 to 44 are comparative examples in which no coating is formed, and the corrosion fatigue life is remarkably reduced. Moreover, these have more C, Si, and Mn than the preferable range, wire drawing workability falls a little, the surface produces a defect, and has a bad influence on corrosion fatigue life.

It is sectional drawing of the steel wire for rubber product reinforcement of this invention. It is a figure for demonstrating the corrosion fatigue test method. It is a figure which shows the example of a corrosion fatigue test result.

Explanation of symbols

1 Steel element wire 2 Plating layer 3 Coating layer 4 Corrosion test plating wire 5 Corrosion test solution C Distance between chucks (mm)
L Test piece length (m)

Claims (9)

  It has a plating layer on the surface of a steel strand having a diameter of 0.1 to 0.4 mm, and on the surface of the plating layer, one or more of Zr, Ti, Si, Mo, Co, and Ni A steel wire for reinforcing rubber products excellent in corrosion fatigue resistance, comprising a coating layer having a thickness of 10 nm or more and 1000 nm or less made of a compound containing oxygen as a main component.   The steel wire for reinforcing rubber products according to claim 1, wherein the plating layer contains 55 to 75% by mass of Cu.   The coating layer is one or both of a metal oxide and a metal hydroxide, and the ratio of the metal species to the total of metal species and oxygen in the coating layer is 30% to 70% in atomic%. The steel wire for reinforcing rubber products having excellent corrosion fatigue resistance characteristics according to claim 1 or 2. The steel strand according to any one of claims 1 to 3, wherein the steel strand is in mass%.
C: 0.4 to 1.1%
Si: 0.2 to 1.5%
Mn: 0.2 to 1.0%
Containing
P: 0.02% or less,
S: Steel wire for reinforcing rubber products excellent in corrosion fatigue resistance, characterized by being limited to 0.02% or less and the balance being Fe and inevitable impurities. Steel strands are also mass%,
Cr: 0.05 to 0.5%,
Cu: 0.05 to 0.3%,
Ni: 0.05 to 0.5%,
Mo: 0.05-0.3%
V: 0.05-0.5%
W: 0.05-0.3%
Co: 0.01 to 0.1%
The steel wire for reinforcing rubber products according to claim 4, wherein the steel wire is excellent in corrosion fatigue resistance.   A twisted steel wire for reinforcing a rubber product excellent in corrosion fatigue resistance, wherein the steel wire for reinforcing a rubber product according to any one of claims 1 to 5 is a twisted wire formed by twisting a plurality of steel wires.   It is a manufacturing method of the steel wire for rubber product reinforcement of any one of Claims 1-3, Comprising: Liquid phase precipitation using the metal fluoride complex on the surface of the plating layer provided in the surface of steel strand A steel for reinforcing rubber products having excellent anti-corrosion fatigue properties, characterized by forming a compound mainly composed of oxygen and one or more of Zr, Ti, Si, Mo, Co, and Ni Wire manufacturing method.   The method for producing a steel wire for reinforcing rubber products according to claim 7, wherein the steel wire has the component composition according to claim 4 or 5. The anode is immersed in the metal fluoride complex solution, and the steel strand having a plating layer on the surface is continuously passed through the metal fluoride complex solution as a cathode, and the current density is in the range of 1 to 10 A / dm ² . The steel wire for reinforcing a rubber product excellent in corrosion fatigue resistance according to claim 7 or 8, comprising a step of forming a film and a step of subsequently drying in a temperature range of 80 ° C to 200 ° C. Production method.

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