Rubber composite, tire

Abstract

Provided is a rubber complex having a steel cord and a rubber that covers at least part of the surface of the steel cord, wherein a first coating that contains Cu is disposed on an end surface of the steel cord in the longitudinal direction.

Description

Technical Field

[0001] The present disclosure relates to a rubber composite, a tire, and a steel cord.

[0002] This application claims priority based on Japanese Application No. 2020-044547 filed on March 13, 2020, and incorporates by reference all the descriptions set forth in the said Japanese application.

Background Art

[0003] For example, Patent Document 1 discloses that in a pneumatic steel radial tire including a carcass layer made of a steel ply in which a steel cord is embedded, a predetermined brass plating is applied to the surface of the steel wire constituting the steel cord.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The rubber composite of the present disclosure has a steel cord and rubber covering at least a part of the surface of the steel cord, and a first coating containing Cu is disposed on the longitudinal end faces of the steel cord.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0007] [Problems to be Solved by the Present Disclosure] In products containing rubber composites such as tires, corrosion sometimes occurs in the vicinity of the end faces of steel cords. In recent years, in order to suppress the replacement frequency of products containing rubber composites, it has been required to enhance durability. For this reason, it has been required to suppress corrosion in the vicinity of the end faces of such steel cords.

[0008] Therefore, an object is to provide a rubber composite in which corrosion of the end face of a steel cord is suppressed. [Effects of the Present Disclosure]

[0009] According to the present disclosure, a rubber composite in which corrosion of the end face of a steel cord is suppressed can be provided.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0011] (1) A rubber composite according to one aspect of the present disclosure includes a steel cord and rubber that covers at least a part of the surface of the steel cord, and a first coating containing Cu is disposed on the end faces in the longitudinal direction of the steel cord.

[0012] The rubber composite according to one aspect of the present disclosure has a first coating on the end faces in the longitudinal direction of the steel cord, whereby the corrosion resistance of the end faces of the steel cord can be improved.

[0013] By containing Cu (copper), the first coating can protect the surface of the steel cord, specifically the end faces in the longitudinal direction, and enhance the corrosion resistance.

[0014] (2) The first coating may further contain S.

[0015] By further containing S (sulfur) in the first coating, copper-sulfur compounds such as the aforementioned Cu and Cu 2 S can be formed, especially protecting the end faces in the longitudinal direction of the steel cord and particularly enhancing the corrosion resistance. Also, when the steel cord and the rubber are adhered via the first coating, copper-sulfur compounds such as Cu 2 S can enhance the adhesive force between the steel cord and the rubber and particularly enhance the durability of the rubber composite.

[0016] (3) The first coating may further contain Zn.

[0017] Zn (zinc) promotes the reaction between Cu and other elements contained in the rubber and promotes the formation of copper compounds such as Cu 2 S. The copper compound particularly protects the end faces in the longitudinal direction of the steel cord and further enhances the corrosion resistance. Also, when the steel cord and the rubber are adhered via the first coating, the copper compound enhances the adhesive force between the steel cord and the rubber and enhances the durability of the rubber composite.

[0018] (4) The first coating may further contain one or more selected from Sn, Cr, Fe, Co, and Ni.

[0019] Sn (tin), Cr (chromium), Fe (iron), Co (cobalt), and Ni (nickel) have a greater ionization tendency than Zn. Therefore, by further containing one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn in the first coating, it can function as sacrificial corrosion protection or make the composite potential of Cu and Zn noble. For this reason, the end faces in the longitudinal direction of the steel cord can be particularly protected and the corrosion resistance can be further enhanced.

[0020] (5) The end face of the steel cord may be covered with the rubber via the first covering.

[0021] By covering the longitudinal end face of the steel cord with the rubber via the first covering, the longitudinal end face of the steel cord can be protected by the rubber in addition to the first covering. Therefore, the corrosion resistance of the longitudinal end face of the steel cord can be enhanced. Furthermore, breakage of the rubber composite can be suppressed, and the durability can be enhanced.

[0022] (6) The end face of the steel cord may be adhered to the rubber via the first covering.

[0023] By adhering the longitudinal end face of the steel cord to the rubber via the first covering, the longitudinal end face of the steel cord can be protected by the rubber in addition to the first covering. Therefore, the corrosion resistance of the longitudinal end face of the steel cord can be enhanced.

[0024] Also, when the rubber composite is applied to a tire or the like, a large force is likely to be applied in the vicinity of the boundary between the longitudinal end face of the steel cord and the rubber. However, since the longitudinal end face of the steel cord is adhered to the rubber via the first covering, the rubber, the first covering, and the steel cord can support the applied force integrally. Therefore, breakage of the rubber composite can be particularly suppressed, and the durability can be enhanced.

[0025] Furthermore, by adhering the longitudinal end face of the steel cord, the first covering, and the rubber, entry of foreign matter such as water between the above members can be particularly prevented. Therefore, entry of foreign matter such as water up to the end face of the steel cord can be suppressed, and the corrosion resistance can be particularly enhanced.

[0026] (7) The first covering may cover 20% or more of the end face.

[0027] By covering more than 20% of the area of the longitudinal end face of the steel cord 11 with the first coating, the corrosion resistance of the end face of the steel cord can be particularly enhanced.

[0028] (8) A second coating containing Cu may be disposed on the side surface of the steel cord.

[0029] By having the second coating on the side surface of the steel cord, the rubber composite can improve the corrosion resistance of the side surface of the steel cord.

[0030] By containing Cu in the second coating, the surface of the steel cord, specifically the side surface, can be protected and the corrosion resistance can be enhanced.

[0031] (9) The tire according to one aspect of the present disclosure includes any one of the rubber composites of (1) to (8).

[0032] The tire according to one aspect of the present disclosure includes the above-described rubber composite. Therefore, corrosion at the longitudinal end face of the steel cord can be suppressed and the durability can be enhanced.

[0033] (10) The steel cord according to one aspect of the present disclosure has a film containing Cu disposed on the longitudinal end face.

[0034] By having the film on the longitudinal end face, the corrosion resistance of the end face of the steel cord according to one aspect of the present disclosure can be improved.

[0035] By containing Cu (copper) in the film, the surface of the steel cord can be protected and the corrosion resistance can be enhanced.

[0036] (11) The film may further contain Zn.

[0037] Zn has a greater ionization tendency than Cu. Therefore, by further containing Zn in addition to Cu in the film, it can function as sacrificial corrosion protection. Thus, the longitudinal end face of the steel cord can be particularly protected and the corrosion resistance can be further enhanced.

[0038] (12) The coating may further contain one or more selected from Sn, Cr, Fe, Co, and Ni.

[0039] Sn, Cr, Fe, Co, and Ni have a greater ionization tendency than Zn. Therefore, by the coating further containing one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn, it can function as sacrificial corrosion protection or increase the noble potential of the combined potential of Cu and Zn. For this reason, the end faces in the longitudinal direction of the steel cord can be particularly protected, and the corrosion resistance can be further enhanced.

[0040] (13) The coating may cover 20% or more of the end face.

[0041] By the coating covering 20% or more of the area of the end faces in the longitudinal direction of the steel cord 11, the corrosion resistance of the end faces of the steel cord can be particularly enhanced.

[0042] [Details of Embodiments of the Present Disclosure] Specific examples of the rubber composite, tire, and steel cord according to one embodiment of the present disclosure (hereinafter referred to as "this embodiment") will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0043] [Rubber Composite] In products including rubber composites such as tires, corrosion sometimes occurs in the vicinity of the end faces of the steel cord. In order to suppress the occurrence of such corrosion, the inventors of the present invention examined the causes of the corrosion.

[0044] As described above, it has conventionally been done to form a coating by plating on the surface of the wire rod of the steel cord.

[0045] When manufacturing a rubber composite using a steel cord having a coating, the metal components of the coating of the steel cord react with the components of the rubber, and a coating, also called an adhesive layer, is formed on the surface of the steel cord. It is considered that the steel cord is protected and its corrosion resistance is enhanced by forming the above coating on the surface of the steel cord.

[0046] However, when manufacturing a rubber composite, it is necessary to cut the steel cord according to the size of the rubber composite. For this reason, at the end face of the steel cord contained in the rubber composite, the wire material is exposed, and no coating is formed on the end face of the steel cord. As a result, in the conventional rubber composite, it is considered that the end face of the steel cord is not protected and corrosion occurs at the end face.

[0047] Based on the above examination results, the inventors of the present invention have completed the rubber composite of the present embodiment that can suppress corrosion at the end face of the steel cord.

[0048] A configuration example of the rubber composite of the present embodiment is shown in FIGS. 1 and 2. FIG. 1 is a perspective view of the rubber composite 10 of the present embodiment, and FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1. Specifically, it shows a cross-sectional view of the end portion in the longitudinal direction of the steel cord 11 on a plane passing through the central axis of the steel cord 11. In FIGS. 1 and 2, the Y-axis direction is parallel to the longitudinal direction of the steel cord 11, and the XZ plane is a plane perpendicular to the longitudinal direction of the steel cord 11. In FIGS. 1 and 2, the X-axis direction is the width direction of the rubber composite 10, and a plurality of steel cords 11 are arranged in a row along the X-axis direction. The Z-axis direction is the thickness direction of the rubber composite 10.

[0049] As shown in FIG. 1, the rubber composite 10 of the present embodiment can have a steel cord 11 and rubber 12 that covers at least a part of the surface of the steel cord 11. And as shown in FIG. 2, the end face 11A in the longitudinal direction of the steel cord 11 can have a first coating 131 which is a coating 13.

[0050] The number of steel cords 11 included in the rubber composite 10 of the present embodiment is not particularly limited and can be selected according to the application. For example, it may be one or a plurality. When the rubber composite 10 of the present embodiment has a plurality of steel cords 11, the arrangement of the steel cords 11 is not particularly limited. For example, as shown in FIG. 1, in the XZ plane, which is a cross section perpendicular to the longitudinal direction of the plurality of steel cords 11, they can be arranged in a row.

[0051] Hereinafter, each member included in the rubber composite of the present embodiment will be described. (1) Steel cord As shown in FIG. 2, the steel cord 11 can have a wire rod 111 and a coating 112 covering the surface of the wire rod 111. In FIGS. 1 and 2, an example in which the steel cord 11 is composed of a single line is shown, but it is not limited to such a form. For example, a steel cord formed by twisting a plurality of steel wires may be used. When the steel cord has a configuration in which a plurality of steel wires are twisted together, it is preferable that each steel wire has a wire rod 111 and a coating 112 covering the surface of the wire rod 111, which will be described below.

[0052] The wire rod 111 included in the steel cord 11 can be, for example, a steel wire, and a high-carbon steel wire is more preferably used.

[0053] The steel cord 11 can have a first coating 1121 covering the end face 11A side in addition to the second coating 1122 covering the side face 11B side of the steel cord 11 as the coating 112.

[0054] By providing the coating 112 on the surface of the wire rod 111 of the steel cord 11, when the rubber composite 10 is formed, a covering 13 can be formed on the surface of the steel cord 11. Specifically, by providing the first coating 1121 covering the end face 11A side in the longitudinal direction of the steel cord 11, when the rubber composite 10 is formed, the first covering 131 can be formed and arranged on the end face 11A in the longitudinal direction of the steel cord 11.

[0055] Further, by providing the second film 1122 that covers the side surface 11B side of the steel cord 11, when the rubber composite 10 is formed, the second covering 132 can be formed and disposed on the side surface 11B side of the steel cord 11.

[0056] When the first film 1121 and the second film 1122 are used to form the rubber composite 10, they can react with the rubber components to form the first covering 131 and the second covering 132. Therefore, when the rubber composite 10 is formed, part of the first film 1121 and the second film 1122 may remain, or all of them may become the first covering 131 and the second covering 132. That is, the rubber composite 10 may not have the first film 1121 and the second film 1122.

[0057] As described above, when manufacturing the rubber composite, it is necessary to cut the steel cord according to the size of the rubber composite. Therefore, in the conventional rubber composite, no film was provided on the longitudinal end surface of the steel cord. And it is considered that the covering is formed by the reaction between the rubber components and the components of the film of the steel cord. Therefore, when there is no film on the longitudinal end surface of the steel cord, no covering is formed on the end surface, and in the conventional rubber composite, corrosion occurred from the longitudinal end surface of the steel cord.

[0058] On the other hand, the steel cord 11 included in the rubber composite 10 of the present embodiment has the first film 1121, which is the film 112, on the longitudinal end surface 11A. Therefore, the rubber composite 10 can have the first covering 131 on the longitudinal end surface of the steel cord 11, and the corrosion resistance of the end surface 11A of the steel cord can be improved.

[0059] The steel cord 11 included in the rubber composite 10 of the present embodiment can also have the second film 1122, which is the film 112, on the side surface 11B. Therefore, the rubber composite 10 can also have the second covering 132 on the side surface of the steel cord 11, and the corrosion resistance of the side surface 11B of the steel cord can also be improved.

[0060] The first coating 1121 can be formed after cutting a steel cord to a predetermined length in order to manufacture the rubber composite 10. Specifically, it can be formed before embedding the steel cord 11 in the rubber 12, or after embedding a part of the steel cord 11 in the rubber 12 and before covering the longitudinal end faces of the steel cord 11 with the rubber 12 or the like.

[0061] The specific means for forming the first coating 1121 is not particularly limited, and various means capable of forming a coating having a desired composition can be used. The first coating 1121 can contain, for example, one or more selected from oxides and metals. For this reason, the first coating 1121 can be formed by various means capable of forming oxides or metals. Examples of the manufacturing method of the first coating 1121 include a coating method of applying a coating liquid containing a predetermined component such as a metal, and an immersion method of immersing the end face 11A side of the steel cord 11 in the coating liquid. Other examples of the manufacturing method of the first coating 1121 include an electroplating method, an electroless plating method, and a displacement plating method. The electroplating method also includes a pen plating method. When the first coating 1121 contains a plurality of components, a plurality of layers corresponding to the plurality of components of the first coating 1121 are formed on the longitudinal end faces of the steel cord 11, and the first coating 1121 can also be formed by performing heat treatment as necessary. Before forming the first coating 1121, it is preferable to perform a pretreatment for removing substances adhering to the surface such as degreasing treatment on the end face 11A of the steel cord 11, but the first coating 1121 may be formed without performing the pretreatment.

[0062] The method for forming the second coating 1122 is not particularly limited. For example, a coating corresponding to the surface of the mother wire for manufacturing the steel cord 11 is formed, and by drawing the mother wire, the second coating 1122 can be formed on the surface of the wire rod 111. That is, the second coating 1122 disposed on the side surface 11B side of the steel cord 11 is derived from the coating formed on the surface of the mother wire before drawing.

[0063] As described above, the first coating 1121 provided on the end face 11A side of the steel cord 11 and the second coating 1122 provided on the side face 11B side are formed at different timings. Therefore, the first coating 1121 and the second coating 1122 may have the same composition and film thickness, or may be different.

[0064] The composition of the first coating 1121 and the second coating 1122, which are the coatings 112, is not particularly limited. The coating 112 preferably contains, for example, Cu (copper). In particular, it is more preferable to further contain Zn (zinc) in addition to Cu.

[0065] Furthermore, it is even more preferable that the coating 112 further contains one or more selected from Sn (tin), Cr (chromium), Fe (iron), Co (cobalt), and Ni (nickel) in addition to Cu and Zn. (2) Rubber The rubber 12 can be manufactured by molding a rubber composition and vulcanizing it as necessary.

[0066] The specific composition of the rubber can be selected according to the use, characteristics, etc. of the rubber composite of the present embodiment, and is not particularly limited. The rubber can contain, for example, a rubber component, sulfur, and a vulcanization accelerator.

[0067] It is preferable that the rubber component contains 60% by mass or more, more preferably 70% by mass or more, and even more preferably 100% by mass of one or more selected from natural rubber (NR: natural rubber) and isoprene rubber (IR: isoprene rubber) in the rubber component.

[0068] This is because by setting the proportion of one or more rubbers selected from natural rubber and isoprene rubber in the rubber component to 60% by mass or more, the breaking strength of the rubber composite can be increased, which is preferable.

[0069] Examples of the rubber components used in admixture with natural rubber or isoprene rubber include one or more selected from styrene-butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), butyl rubber (IIR), and acrylonitrile-butadiene rubber (NBR).

[0070] Although sulfur is not particularly limited, for example, sulfur generally used as a vulcanizing agent in the rubber industry can be used.

[0071] Although the sulfur content of the rubber is not particularly limited, it is preferably, for example, 5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0072] This is because by setting the ratio of sulfur to 5 parts by mass or more with respect to 100 parts by mass of the rubber component, the crosslink density of the resulting rubber can be increased, and in particular, the adhesion between the steel cord and the rubber can be increased. Also, by setting the ratio of sulfur to 8 parts by mass or less with respect to 100 parts by mass of the rubber component, sulfur can be dispersed particularly uniformly in the rubber, and blooming can be suppressed, which is preferable.

[0073] The vulcanization accelerator is not particularly limited either. For example, sulfenamide-based accelerators such as N,N′-dicyclohexyl-2-benzothiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, and N-oxydiethylene-2-benzothiazolylsulfenamide are preferably used. Also, if desired, thiazole-based accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyldisulfide, and tetrabenzylthi Back um disulfide, tetramethylthi Back um disulfide, tetraethylthi Back um disulfide, tetrakis(2-ethylhexyl)thi Back um disulfide, tetramethylthi Back um monosulfide and other thi BackA mu-based accelerator may be used.

[0074] The rubber composition used for the rubber composite of the present embodiment can be manufactured by kneading the above-described respective components by a conventional method and then performing heat treatment and extrusion.

[0075] Moreover, it is preferable that the rubber of the rubber composite of the present embodiment contains one or more selected from metallic cobalt and compounds containing cobalt.

[0076] Examples of the compound containing cobalt include cobalt organic acid salts and cobalt inorganic acid salts.

[0077] As the cobalt organic acid salt, for example, one or more selected from cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tallate, etc. can be preferably used. Note that the cobalt organic acid salt may be a complex salt in which a part of the organic acid is replaced with boric acid.

[0078] As the cobalt inorganic acid salt, for example, one or more selected from cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, cobalt chromate can be preferably used.

[0079] In particular, it is more preferable that the rubber of the rubber composite of the present embodiment contains a cobalt organic acid salt. This is because, by containing the cobalt organic acid salt, the initial adhesion performance between the steel cord and the rubber can be particularly improved. Note that the initial adhesion performance means the adhesion performance between the steel cord and the rubber at the time of manufacturing the rubber composite, for example, immediately after vulcanization.

[0080] Moreover, according to the studies by the inventors of the present invention, by adding cobalt to the rubber, Cu in the coating 2The proportion of copper compounds such as S can be increased, and the adhesive force between the steel cord and the rubber can be increased. When cobalt organic acid is used as the cobalt to be added, this tendency becomes remarkable. Therefore, it is preferable that the rubber of the rubber composite of the present embodiment contains cobalt, particularly cobalt organic acid, and thereby a rubber composite particularly excellent in durability can be obtained.

[0081] In addition to the above rubber components, sulfur, vulcanization accelerator, cobalt, etc., the rubber can contain any components. The rubber can also contain well-known rubber additives such as reinforcing agents (carbon black, silica, etc.), waxes, and anti-aging agents.

[0082] The rubber 12 can cover at least a part of the surface of the steel cord 11. By covering at least a part of the surface of the steel cord 11 with the rubber 12, even in the part not directly covered with the rubber 12, in the part where the coating 112 is provided as described above, the components of the coating 112 and the components of the rubber 12 can react to form the covering 13, and the corrosion resistance can be improved.

[0083] Therefore, the rubber 12 can cover at least a part of the end face 11A of the steel cord 11 in the longitudinal direction, and can also cover the entire end face 11A. Further, the rubber 12 can cover at least a part of the side face 11B of the steel cord 11, and can also cover the entire side face 11B of the steel cord 11. The rubber 12 can also cover the entire surface of the steel cord 11.

[0084] From the viewpoint of protecting the end face 11A in the longitudinal direction of the steel cord 11 and particularly improving the corrosion resistance, it is preferable that the rubber 12 covers at least a part of the end face 11A in the longitudinal direction of the steel cord 11, and it is more preferable to cover the entire end face 11A in the longitudinal direction of the steel cord 11. (3) Covering (3-1) First covering As described above, in the rubber composite 10 of the present embodiment, the first covering 131 which is the covering 13 can be provided on the end face 11A in the longitudinal direction of the steel cord 11.

[0085] In FIG. 2, the first coating 131 is shown as being formed with a uniform thickness along the longitudinal end face 11A of the steel cord 11. However, FIG. 2 is a schematic illustration and is not limited to such a form. For example, the first coating 131 may be arranged so as to be scattered on the surface of the longitudinal end face 11A of the steel cord 11, or may have a film shape so as to cover the entire longitudinal end face 11A of the steel cord 11 as shown in FIG. 2.

[0086] The first coating 131 is considered to be formed by the reaction of the components contained in the first coating film 1121 and the components contained in the rubber 12, etc. Therefore, the composition of the first coating 131 changes according to the composition of the first coating film 1121 and the rubber 12 and is not particularly limited. However, the first coating 131 preferably contains, for example, Cu (copper). This is because when the first coating 131 contains Cu, the surface of the steel cord 11, specifically the longitudinal end face, can be protected and the corrosion resistance can be enhanced.

[0087] As described above, the first coating film 1121 can further contain Zn (zinc) in addition to Cu. Further, the first coating film 1121 can further contain one or more selected from Sn (tin), Cr (chromium), Fe (iron), Co (cobalt), and Ni (nickel) in addition to Cu and Zn. Therefore, the first coating 131 can also further contain Zn in addition to Cu. Further, the first coating 131 can further contain one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn.

[0088] When the first coating film 1121 contains Zn in addition to Cu, the first coating 131 can also contain Zn in addition to Cu. Zn promotes the reaction between Cu and other elements contained in the rubber 2Promote the formation of copper compounds such as S. The copper compound particularly protects the longitudinal end face 11A of the steel cord 11, further enhancing the corrosion resistance. Also, when the steel cord 11 and the rubber 12 are adhered via the first coating 131, the copper compound increases the adhesive force between the steel cord and the rubber, enhancing the durability of the rubber composite.

[0089] Also, Sn, Cr, Fe, Co, Ni have a greater ionization tendency than Zn. Therefore, when the first coating 131 further contains one or more selected from Sn, Cr, Fe, Co, Ni in addition to Cu and Zn, it functions as sacrificial corrosion protection or can ennoble the composite potential of Cu and Zn. Thus, the longitudinal end face 11A of the steel cord 11 can be particularly protected, further enhancing the corrosion resistance.

[0090] When manufacturing the rubber composite, vulcanization is usually performed. Therefore, it is more preferable for the first coating 131 to further contain S (sulfur) added during vulcanization. By the first coating 131 further containing S, the above-mentioned copper-sulfur compounds such as Cu and Cu 2 form, particularly protecting the longitudinal end face 11A of the steel cord 11 and particularly enhancing the corrosion resistance. Also, when the steel cord 11 and the rubber 12 are adhered via the first coating 131, the copper-sulfur compounds such as Cu 2 increase the adhesive force between the steel cord 11 and the rubber, particularly enhancing the durability of the rubber composite.

[0091] The first coating 131 can further contain a part of the components of the first film 1121. As described above, the first film 1121 can contain one or more selected from oxides and metals. Therefore, the first coating 131 can also contain one or more selected from oxides and metals derived from the first film 1121. When the first coating 131 contains one or more selected from oxides and metals, the adhesion to the first film 1121 becomes particularly high. For this reason, the corrosion resistance of the steel cord 11 can be particularly enhanced, and at the location where the steel cord 11 and the rubber 12 are adhered, the adhesive force between the steel cord 11 and the rubber 12 can also be enhanced.

[0092] As described above, in the rubber composite 10 of the present embodiment, it is preferable that the rubber 12 covers at least a part of the longitudinal end face 11A of the steel cord 11, and it is more preferable that the rubber 12 covers the entire longitudinal end face 11A of the steel cord 11.

[0093] During the production of the rubber composite 10, by arranging the rubber 12 so as to cover at least a part of the longitudinal end face 11A of the steel cord 11 as described above, the longitudinal end face 11A of the steel cord 11 can be brought into a state of being adhered to the rubber 12 via the first coating 131. That is, on the longitudinal end face 11A side of the steel cord 11, the rubber 12, the first coating 131, and the steel cord 11 are arranged in that order from the outer surface side of the rubber composite 10, and each member of the rubber 12, the first coating 131, and the steel cord 11 can be brought into an adhered state.

[0094] As described above, since the longitudinal end face 11A of the steel cord 11 is adhered to the rubber 12 via the first coating 131, in addition to the first coating 131, the rubber 12 can protect the longitudinal end face 11A of the steel cord 11. For this reason, the corrosion resistance of the longitudinal end face 11A of the steel cord 11 can be enhanced.

[0095] In addition, when the rubber composite 10 is applied to a tire or the like, a large force is likely to be applied in the vicinity of the boundary between the longitudinal end face 11A of the steel cord 11 and the rubber 12. However, since the longitudinal end face 11A of the steel cord 11 is adhered to the rubber 12 via the first covering 131, the rubber 12, the first covering 131, and the steel cord 11 can be integrated to support the applied force. Therefore, the rubber composite 10 is particularly suppressed from being damaged, and the durability can be enhanced.

[0096] Furthermore, by the adhesion of the longitudinal end face 11A of the steel cord 11, the first covering 131, and the rubber 12, it is possible to particularly prevent foreign matters such as water from entering between the above members. Therefore, it is possible to suppress the intrusion of foreign matters such as water up to the longitudinal end face 11A of the steel cord 11, and the corrosion resistance can be particularly enhanced.

[0097] However, for example, when the rubber composite 10 is used for a long period of time, the reaction between the components of the rubber 12 and the components of the first coating 1121 may progress, and the state of the first covering 131 and its periphery may change. In addition, a repeated force may be applied between the rubber 12 and the steel cord 11, and a gap or the like may be generated between the two members. Therefore, when the rubber composite 10 is used for a long period of time, the adhesive force between the rubber 12 and the steel cord 11 may decrease.

[0098] However, even when the adhesive force between the rubber 12 and the steel cord 11 decreases, in the rubber composite 10, since the first covering 131 is disposed on the end face 11A of the steel cord 11, it has the effect of protecting the end face 11A of the steel cord 11 and improving the corrosion resistance.

[0099] Therefore, the longitudinal end face 11A of the steel cord 11 is not limited to the form adhered to the rubber 12 via the first covering 131, and the longitudinal end face 11A of the steel cord 11 can be in a form covered with rubber via the first covering.

[0100] Since the longitudinal end face 11A of the steel cord 11 is covered with the rubber 12 via the first covering, in addition to the first covering 131, the rubber 12 can protect the longitudinal end face 11A of the steel cord 11. Therefore, the corrosion resistance of the longitudinal end face 11A of the steel cord 11 can be enhanced. Furthermore, it is possible to suppress the rubber composite 10 from being damaged and enhance the durability of the rubber composite 10.

[0101] The fact that the longitudinal end face 11A of the steel cord is covered with the rubber 12 via the first covering 131 includes the following two forms in addition to the aforementioned adhered case. As the first form, at the longitudinal end face 11A of the steel cord 11, from the outer surface side of the rubber composite 10, the rubber 12, the first covering 131, and the steel cord 11 are arranged in this order, and the members are in contact with each other. Here, the fact that the members are in contact with each other means that there is no adhesive force between the members, but they are in contact without gaps. As the second form, at the longitudinal end face 11A of the steel cord 11, from the outer surface side of the rubber composite 10, the rubber 12, the first covering 131, and the steel cord 11 are arranged in this order, and it is a form including gaps in at least a part between the members.

[0102] In addition, in any case where the longitudinal end face 11A of the steel cord 11 is covered with the rubber via the first covering 131, the first coating 1121 may be arranged on the surface of the steel cord 11 facing the first covering 131.

[0103] As described above, in the conventional rubber composite, since the first coating 1121 which is the coating 112 was not formed on the end face 11A side of the steel cord 11, the first covering 131 was not disposed on the end face 11A of the steel cord 11 either. For this reason, if the first covering 131 is disposed on the end face 11A of the steel cord 11 even a little, the corrosion resistance can be enhanced as compared with the conventional case, and the degree to which the first covering 131 is disposed is not particularly limited. However, it is preferable that the first covering 131 covers 20% or more of the area of the end face 11A in the longitudinal direction of the steel cord 11, and more preferably 40% or more. Since the corrosion resistance of the end face 11A of the steel cord 11 can be particularly enhanced by the first covering 131 covering 20% or more of the area of the end face 11A in the longitudinal direction of the steel cord 11, it is preferable.

[0104] Since the first covering 131 can also cover the entire end face 11A of the steel cord 11, the first covering 131 can cover 100% or less of the area of the end face 11A of the steel cord 11.

[0105] The method for measuring the ratio of the area covered by the first covering 131 on the end face 11A of the steel cord 11 is not particularly limited. For example, when a part of the end face side rubber 121 which is a part of the rubber 12 disposed on the end face 11A side of the steel cord 11 of the rubber composite 10 is peeled off, as shown in FIG. 3, the end face 11A side of the steel cord 11 is exposed. For this reason, the ratio of the area occupied by the rubber 12 can be calculated, excluding the region where the steel cord 11 such as the first coating 1121 is exposed, out of the end face 11A of the steel cord 11. Since the rubber 12 remaining on the end face 11A of the steel cord 11 corresponds to the location where the first covering 131 was formed, the ratio of the area covered by the first covering 131 on the end face 11A of the steel cord 11 can be calculated from the ratio of the area occupied by the rubber 12 as described above.

[0106] Further, when the end face side rubber 121 is peeled off, either element distribution mapping between the end face side rubber 121 and the end face 11A side of the steel cord exposed after peeling may be performed, and the ratio of the area where the first covering 131 covers the end face 11A of the steel cord 11 may be measured. When rubber remains on the end face 11A side of the steel cord, the end face 11A side of the steel cord can be subjected to element distribution mapping, and when no rubber remains on the end face 11A side of the steel cord, the side of the end face side rubber 121 can be subjected to element distribution mapping.

[0107] When the above element distribution mapping is performed, a region where both the components of the first coating 1121 and the components of the rubber, for example, Cu and S, are distributed becomes the region where the first covering 131 is formed. Therefore, from the result of the element distribution mapping, by obtaining the ratio of the area of the region where the first covering 131 is formed out of the end face 11A of the steel cord 11, the ratio of the area where the first covering 131 covers the end face 11A of the steel cord 11 can be calculated.

[0108] Note that the means for performing the element distribution mapping is not particularly limited, and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscop) or the like can be used. When performing element mapping on the end face side rubber, since the object to be measured is an insulator, for example, low acceleration voltage SEM and EDX can be used. (3-2) Second covering The rubber composite 10 can also have a second covering 132, which is a covering 13, on the side surface 11B side of the steel cord 11. The second covering 132 is considered to be formed by the reaction of the components contained in the second coating 1122 and the components contained in the rubber 12 and the like. Therefore, the composition of the second covering 132 changes according to the composition of the second coating 1122 and the rubber 12 and is not particularly limited, but the second covering 132 preferably contains, for example, Cu (copper). This is because when the second covering 132 contains Cu, the surface of the steel cord 11, specifically the side surface, can be protected and the corrosion resistance can be enhanced.

[0109] Also, as described above, the second coating 1122 can further contain Zn (zinc) in addition to Cu. Therefore, the second covering 132 can also further contain Zn in addition to Cu. Zn promotes the reaction between Cu and other elements contained in the rubber, and promotes the formation of copper compounds such as Cu 2 S. The copper compound particularly protects the side surface 11B of the steel cord 11 and further enhances the corrosion resistance. Also, when the steel cord 11 and the rubber 12 are adhered via the second covering 132, the copper compound enhances the adhesive force between the steel cord and the rubber, and enhances the durability of the rubber composite.

[0110] The second coating 1122 can further contain one or more selected from Sn (tin), Cr (chromium), Fe (iron), Co (cobalt), and Ni (nickel) in addition to Cu and Zn. Therefore, the second covering 132 can also further contain one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn. Sn, Cr, Fe, Co, and Ni have a greater ionization tendency than Zn. Therefore, by the second covering 132 further containing one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn, it can function as sacrificial corrosion protection or make the composite potential of Cu and Zn noble. Therefore, the side surface 11B of the steel cord 11 can be particularly protected and the corrosion resistance can be further enhanced.

[0111] It is more preferable that the second covering 132 further contains S (sulfur) added during vulcanization. By the second covering 132 further containing S, copper-sulfur compounds such as the aforementioned Cu and Cu 2 S can be formed. The copper-sulfur compound can enhance the adhesive force between the steel cord 11 and the rubber when the steel cord 11 and the rubber 12 are adhered via the second covering 132, and particularly enhance the durability of the rubber composite.

[0112] As described above, in the rubber composite 10 of the present embodiment, it is preferable that the rubber 12 covers at least a part of the side surface 11B of the steel cord 11, and it is more preferable that the rubber 12 covers the entire side surface 11B of the steel cord 11.

[0113] When manufacturing the rubber composite 10, by arranging the rubber 12 so as to cover at least a part of the side surface 11B of the steel cord 11 as described above, the side surface 11B of the steel cord 11 can be adhered to the rubber 12 via the second covering 132. That is, on the side surface 11B side of the steel cord 11, the rubber 12, the second covering 132, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10, and each member of the rubber 12, the second covering 132, and the steel cord 11 can be in an adhered state.

[0114] As described above, since the side surface 11B of the steel cord 11 adheres to the rubber 12 via the second covering 132, in addition to the second covering 132, the side surface 11B of the steel cord 11 can be protected by the rubber 12. Therefore, the corrosion resistance of the side surface 11B of the steel cord 11 can be enhanced.

[0115] Also, when the rubber composite 10 is applied to a tire or the like, a large force is likely to be applied in the vicinity of the boundary between the side surface 11B of the steel cord 11 and the rubber 12. However, since the side surface 11B of the steel cord 11 is adhered to the rubber 12 via the second covering 132, the rubber 12, the second covering 132, and the steel cord 11 can support the force applied integrally. Therefore, the breakage of the rubber composite 10 is particularly suppressed, and the durability can be enhanced.

[0116] Furthermore, since the side surface 11B of the steel cord 11, the second covering 132, and the rubber 12 are adhered, it is possible to particularly prevent foreign substances such as water from entering between the above members. Therefore, the intrusion of foreign substances such as water up to the side surface 11B of the steel cord 11 is suppressed, and the corrosion resistance can be enhanced.

[0117] However, for example, when the rubber composite 10 is used over a long period of time, the reaction between the components of the rubber 12 and the components of the second film 1122 may progress, and the state of the second coating 132 and its surroundings may change. Also, a repetitive force may be applied between the rubber 12 and the steel cord 11, and a gap or the like may occur between the two members. Therefore, when the rubber composite 10 is used over a long period of time, the adhesive force between the rubber 12 and the steel cord 11 may decrease.

[0118] However, even when the adhesive force between the rubber 12 and the steel cord 11 decreases, in the rubber composite 10, since the second coating 132 is disposed on the side surface 11B of the steel cord 11, it has the effect of protecting the side surface 11B of the steel cord 11 and improving the corrosion resistance.

[0119] Therefore, the side surface 11B of the steel cord 11 is not limited to the form of being adhered to the rubber 12 via the second coating 132, and the side surface 11B of the steel cord 11 can be in the form of being covered by the rubber via the second coating.

[0120] Since the side surface 11B of the steel cord 11 is covered by the rubber 12 via the second coating, in addition to the second coating 132, the side surface 11B of the steel cord 11 can be protected by the rubber 12. Therefore, the corrosion resistance of the side surface 11B of the steel cord 11 can be enhanced. Furthermore, breakage of the rubber composite 10 can be suppressed, and the durability of the rubber composite 10 can be enhanced.

[0121] The fact that the side surface 11B of the steel cord is covered with rubber via the second covering includes the above-described adhered case and the following two forms. As the first form, on the side surface 11B of the steel cord 11, from the outer surface side of the rubber composite 10, the rubber 12, the second covering 132, and the steel cord 11 are arranged in this order, and the members are in contact with each other. Here, the fact that the members are in contact with each other means that there is no adhesive force between the members, but they are in contact without gaps. As the second form, on the side surface 11B of the steel cord 11, from the outer surface side of the rubber composite 10, the rubber 12, the second covering 132, and the steel cord 11 are arranged in this order, and it is a form including gaps in at least a part between the members.

[0122] In addition, in any case where the side surface 11B of the steel cord 11 is covered with rubber via the second covering 132, a second coating 1122 may be arranged on the surface of the steel cord 11 facing the second covering 132. 〔Tire〕 Next, the tire in the present embodiment will be described with reference to FIG. 4.

[0123] The tire of the present embodiment can include the above-described rubber composite.

[0124] FIG. 4 shows a cross-sectional view of the tire 40 according to the present embodiment in a plane perpendicular to the circumferential direction. In FIG. 4, only the left side portion of the center line CL is shown, but with CL as the axis of symmetry, the same structure continues on the right side of CL.

[0125] As shown in FIG. 4, the tire 40 includes a tread portion 41, a sidewall portion 42, and a bead portion 43.

[0126] The tread portion 41 is the part that contacts the road surface. The bead portion 43 is provided on the inner diameter side of the tire 40 with respect to the tread portion 41. The bead portion 43 is the part that contacts the rim of the wheel of the vehicle. The sidewall portion 42 connects the tread portion 41 and the bead portion 43. When the tread portion 41 receives an impact from the road surface, the sidewall portion 42 elastically deforms to absorb the impact.

[0127] The tire 40 includes an inner liner 44, a carcass 45, a belt layer 46, and a bead wire 47.

[0128] The inner liner 44 is made of rubber and seals the space between the tire 40 and the wheel.

[0129] The carcass 45 forms the skeleton of the tire 40. The carcass 45 is composed of organic fibers such as polyester, nylon, rayon, or steel cords, and rubber. The above-described rubber composite can also be used for the carcass 45.

[0130] The bead wire 47 is provided in the bead portion 43. The bead wire 47 receives the tensile force acting on the carcass 45.

[0131] The belt layer 46 tightens the carcass 45 to increase the rigidity of the tread portion 41. In the example shown in FIG. 4, the tire 40 has two belt layers 46.

[0132] The two belt layers 46 can be stacked in the radial direction of the tire 40, and the above-described rubber composite can be used.

[0133] The tire of the present embodiment contains the above-described rubber composite. Therefore, corrosion at the longitudinal end face of the steel cord can be suppressed, and the durability can be improved. [Steel cord] The steel cord of the present embodiment can have the same configuration as the steel cord 11 described with the rubber composite. Therefore, some of the overlapping explanations will be omitted.

[0134] Fig. 5 schematically shows a cross-sectional view of the present embodiment of the steel cord taken along a plane passing through the central axis of the steel cord. In Fig. 5, the Y-axis direction is parallel to the longitudinal direction of the steel cord 11, and the XZ plane is a plane perpendicular to the longitudinal direction of the steel cord 11.

[0135] As shown in Fig. 5, the steel cord 11 of the present embodiment can include a wire rod 111 and a coating 112 covering the surface of the wire rod 111. In Fig. 5, the steel cord 11 shows an example of a single-wire steel cord composed of one wire, but it is not limited to such a form as described above. For example, it may be a steel cord formed by twisting a plurality of steel wires. When the steel cord has a configuration in which a plurality of steel wires are twisted together, it is preferable that each steel wire has a wire rod 111 and a coating 112 covering the surface of the wire rod 111 as described below.

[0136] The wire rod 111 included in the steel cord 11 can be, for example, a steel wire, and a high-carbon steel wire is more preferably used.

[0137] The steel cord 11 can have a first coating 1121 covering the end face in the longitudinal direction of the steel cord 11 as the coating 112. The first coating 1121 may cover the entire surface of the end face 11A in the longitudinal direction of the steel cord 11, or may cover a part of the end face 11A.

[0138] In addition, the steel cord 11 can have a second coating 1122 covering the side surface 11B side of the steel cord 11 as the coating 112. The second coating 1122 may cover the entire surface of the side surface 11B of the steel cord 11, or may cover a part of the side surface 11B.

[0139] By providing the coating 112 on the surface of the wire rod 111 of the steel cord 11, the corrosion resistance of the steel cord 11 can be enhanced as compared with the case of only the wire rod 111.

[0140] When manufacturing a rubber composite or the like using a steel cord, it is necessary to cut it according to the required size or the like. For this reason, in the conventional steel cord, a coating was not provided on the end face in the longitudinal direction. And when there was no coating on the end face in the longitudinal direction of the steel cord, corrosion occurred from the end face in the longitudinal direction of the steel cord.

[0141] On the other hand, the steel cord 11 of the present embodiment can improve the corrosion resistance particularly by having the first coating 1121 that covers the end face 11A side in the longitudinal direction.

[0142] In addition, the steel cord 11 of the present embodiment can also protect the side face 11B and improve the corrosion resistance by having the second coating 1122 that covers the side face 11B side.

[0143] The first coating 1121 can be formed after cutting the steel cord to a predetermined length in order to manufacture the rubber composite 10. Specifically, it can be formed after cutting the steel cord 11.

[0144] The specific means for forming the first coating 1121 is not particularly limited, and various means capable of forming a coating having a desired composition can be used. The first coating 1121 can contain, for example, one or more selected from oxides and metals. For this reason, the first coating 1121 can be formed by various means capable of forming oxides or metals. Since the manufacturing method of the first coating 1121 has already been described, the description is omitted here.

[0145] The method for forming the second coating 1122 is not particularly limited. For example, a coating corresponding to the surface of the mother wire for manufacturing the steel cord 11 is formed, and by drawing the mother wire, the second coating 1122 can be formed on the surface of the wire rod 111. That is, the second coating 1122 disposed on the side face 11B side of the steel cord 11 is derived from the coating formed on the surface of the mother wire before drawing.

[0146] The first coating 1121 provided on the end face 11A side of the steel cord 11 and the second coating 1122 provided on the side face 11B side are formed at different timings. Therefore, the first coating 1121 and the second coating 1122 may have the same composition and film thickness, or may be different.

[0147] The composition of the first coating 1121 and the second coating 1122, which are the coatings 112, is not particularly limited. The first coating 1121 preferably contains, for example, Cu (copper). This is because when the first coating 1121 contains Cu, the end face of the steel cord 11 can be protected and the corrosion resistance can be enhanced.

[0148] The first coating 1121 more preferably further contains Zn (zinc) in addition to Cu.

[0149] Zn has a greater ionization tendency than Cu. Therefore, when the second coating 1122 further contains Zn in addition to Cu, it can function as sacrificial corrosion protection. Thus, the end face 11A in the longitudinal direction of the steel cord 11 can be particularly protected and the corrosion resistance can be further enhanced.

[0150] Furthermore, the second coating 1122 more preferably further contains one or more selected from Sn (tin), Cr (chromium), Fe (iron), Co (cobalt), and Ni (nickel) in addition to Cu and Zn.

[0151] Sn, Cr, Fe, Co, and Ni have a greater ionization tendency than Zn. Therefore, when the second coating 1122 further contains one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn, it can function as sacrificial corrosion protection or increase the composite potential of Cu and Zn to noble. Thus, the end face 11A in the longitudinal direction of the steel cord 11 can be particularly protected and the corrosion resistance can be further enhanced.

[0152] For the second coating 1122 as well, the same materials as those for the first coating 1121 can be preferably used. That is, the second coating 1122 preferably contains Cu. Further, the second coating 1122 more preferably further contains Zn in addition to Cu. The second coating 1122 even more preferably further contains one or more selected from Sn, Cr, Fe, Co, and Ni in addition to Cu and Zn. The reason is the same as that for the first coating 1121, so the explanation is omitted.

[0153] In the conventional steel cord, the first coating 1121 which is the coating 112 was not formed on the end face 11A side of the steel cord 11. For this reason, if the first coating 1121 is disposed on the end face 11A of the steel cord 11 even a little, the corrosion resistance can be enhanced as compared with the conventional case, and the degree of arrangement of the first coating 1121 is not particularly limited. However, it is preferable that the first coating 1121 covers 20% or more of the area of the end face 11A in the longitudinal direction of the steel cord 11, and more preferably 40% or more. Since the first coating 1121 covers 20% or more of the area of the end face 11A in the longitudinal direction of the steel cord 11, the corrosion resistance of the end face 11A of the steel cord 11 can be particularly enhanced, which is preferable.

[0154] Since the first coating 1121 can also cover the entire end face 11A of the steel cord 11, the first coating 1121 can cover 100% or less of the area of the end face 11A of the steel cord 11.

[0155] The method for measuring the ratio of the area covered by the first coating 1121 on the end face 11A of the steel cord 11 is not particularly limited. It can be evaluated in the same manner as in the case of the first coating described above.

[0156] That is, for example, first, a rubber composite 10 is formed using a steel cord 11 for evaluation. When a part of the rubber 12 on the end face 11A side of the steel cord 11, i.e., the end face side rubber 121, of the obtained rubber composite 10 is peeled off, as shown in FIG. 3, the end face 11A side of the steel cord 11 is exposed. Therefore, the ratio of the area occupied by the rubber 12 can be calculated for the end face 11A of the steel cord 11, excluding, for example, the first coating 1121 and the region where the steel cord 11 is exposed. Note that the rubber 12 remaining on the end face 11A of the steel cord 11 corresponds to at least the location where the first coating 1121 was formed. Therefore, based on the ratio of the area occupied by the rubber 12 as described above, the ratio of the area where at least the first coating 1121 covers the end face 11A of the steel cord 11 can be calculated.

[0157] However, a part of the rubber may peel off even at the location where the first coating 1121 was formed. Therefore, the area ratio of the first coating 1121 covering the longitudinal end face 11A of the steel cord 11 is equal to or greater than the area ratio calculated by the above method.

[0158] Also, elemental distribution mapping of the end face 11A of the steel cord 11 can be performed to calculate the ratio of the area where the first coating 1121 covers the end face 11A of the steel cord 11.

[0159] Specifically, when elemental distribution mapping of the end face of the steel cord 11 is performed, the region where the components of the first coating 1121 are distributed becomes the region where the first coating 1121 is formed. Therefore, from the results of the elemental distribution mapping, by obtaining the ratio of the area of the region where the first coating 1121 is formed on the end face 11A of the steel cord 11, the ratio of the area where the first coating 1121 covers the end face 11A of the steel cord 11 can be calculated.

[0160] Note that the means for performing elemental distribution mapping is not particularly limited, and SEM-EDX or the like can be used.

[0161] The thickness of the first film 1121 is not particularly limited, but the average thickness is preferably 5 nm or more and 2 μm or less, and more preferably 0.1 μm or more and 1.5 μm or less.

[0162] This is because by setting the average thickness of the first film 1121 to 5 nm or more, the corrosion resistance of the end face can be particularly enhanced. Further, when it is a rubber composite, a first coating 131 with a sufficient thickness can be formed, thereby enhancing the corrosion resistance of the end face.

[0163] By setting the average thickness of the first film 1121 to 2 μm or less, the productivity during the production of the steel cord can be enhanced. Further, when applied to a rubber composite, if the first film 1121 is made too thick, the first coating 131 may become porous, and there is a risk that the effect of improving the corrosion resistance of the end face 11A may be suppressed.

[0164] The method for obtaining the average thickness of the first film 1121 is not particularly limited. For example, measurement can be performed using a fluorescent X-ray film thickness meter. The measurement is performed at a total of three points, namely, the center of the end face 11A of the steel cord 11 and two measurement points on the line segment passing through the center, and the average value can be taken as the average thickness of the first film 1121.

[0165] The line segment passing through the center of the end face 11A of the steel cord 11 is the line segment that is the diameter of the circle that is the contour line of the end face 11A. Here, let the diameter of the circle that is the contour line of the end face 11A be D. In this case, the two measurement points are two points at a distance of 0.25D from the center on the line segment that is the diameter of the circle that is the contour line of the end face 11A, which is arbitrarily drawn so as to pass over the first film 1121 on the end face 11A.

[0166] Although the embodiments have been described in detail above, the present invention is not limited to specific embodiments, and various modifications and changes are possible within the scope described in the claims.

Examples

[0167] Specific examples will be given below for explanation, but the present invention is not limited to these examples. (Evaluation method) First, the evaluation method of the rubber composite prepared in the following experimental examples will be described. (1) Evaluation of the corrosion resistance of the rubber composite Regarding the rubber composite 10 prepared in each of the following experimental examples, when the end face side rubber 121 on the end face 11A side of the steel cord 11 was peeled off, the corrosion resistance was evaluated by the ratio of the area occupied by the rubber 12 in the longitudinal end face 11A of the steel cord 11.

[0168] In the evaluation, in the image of the longitudinal end face 11A side of the steel cord 11 after peeling off the end face side rubber 121, a boundary line was drawn between the portion where the rubber 12 remained visually and the portion where the first coating 1121 and the longitudinal end face 11A of the steel cord 11 were exposed. Also, the contour line of the end face 11A was drawn together. Such a boundary line and the contour line of the end face 11A are lines surrounding the portion where the rubber 12 remains. Then, the portion where the rubber 12 remains surrounded by the boundary line and the contour line of the end face 11A and the other portion were separated by binarization processing, and the area of the portion where the rubber 12 remains was calculated.

[0169] Then, the ratio of the area occupied by the rubber 12 in one longitudinal end face of an arbitrary steel cord in the rubber composite was obtained.

[0170] When the ratio of the area of the rubber 12 in the longitudinal end face of the steel cord was 80% or more, it was evaluated as A; when it was 60% or more and less than 80%, it was evaluated as B; when it was 20% or more and less than 60%, it was evaluated as C; and when it was less than 20%, it was evaluated as D.

[0171] In each of the following experimental examples 1-1 to 1-10, two rubber composites were manufactured for evaluation. And for one rubber composite, the above corrosion resistance evaluation was performed immediately after manufacturing (initial evaluation). For the other rubber composite, after being subjected to a damp heat test, the above corrosion resistance evaluation was performed. The damp heat test is a test in which the rubber composite is placed in an environment with a temperature of 80°C and a relative humidity of 95% for 150 hours (damp heat evaluation).

[0172] Both the above initial evaluation and the damp heat evaluation mean that A is the best, and the evaluations of B, C, and D become worse in this order.

[0173] When the rubber is peeled off, the rubber remaining on the end face of the steel cord corresponds to the location where the coating is formed. Therefore, the higher the damp heat evaluation after the damp heat test, the more it can be said that the end face of the steel cord is continuously protected by a stable coating even after the damp heat test, and it can be said that it is a rubber composite that suppresses the corrosion of the end face of the steel cord.

[0174] However, as shown in Table 1, there is a correlation between the damp heat evaluation and the initial evaluation. When the initial evaluation is excellent, it can be said that it is a rubber composite that suppresses the corrosion of the end face of the steel cord. Therefore, only the initial evaluation was carried out after Experimental Example 2.

[0175] In addition, in the initial evaluation, when the rubber was peeled off, the rubber portion remaining on the end face of the steel cord also corresponded to at least the location where the first coating 1121 was formed. Therefore, the result of the initial evaluation can also be said to be the ratio of the area of at least the portion where the first coating 1121 is formed among the end faces in the longitudinal direction of the steel cord. (2) Evaluation of the corrosion resistance of the steel cord Evaluation was carried out using electrochemical measurement (LSV: Linear Sweep Voltammetry). Specifically, the evaluation sample was immersed in a sulfuric acid aqueous solution with a pH of 1, and the current flowing at 0 V (reference electrode: Ag / AgCl, counter electrode: Pt) was observed.

[0176] The evaluation samples were 30 steel cords prepared under the same conditions so that the influence of the ends could be easily confirmed. 10 mm from the end face where the first coating was formed was immersed in the above sulfuric acid aqueous solution, and the above current was measured.

[0177] The current value measured for the steel cord before forming the plating film on the end face prepared in "(Preparation of the steel cord)" of Experimental Example 1-1 below by the above measurement method, that is, the corrosion current, was 10 mA / cm 2 It was.

[0178] Therefore, when the measured current value is less than 10 mA / cm 2 it means excellent corrosion resistance, and when the current value is 10 mA / cm 2 or more, it means inferior corrosion resistance.

[0179] (Experimental Example) Hereinafter, the experimental conditions will be described. [Experimental Example 1] A rubber composite and a steel cord were produced according to the following procedure, and the corrosion resistance was evaluated. Experimental Examples 1-1 to 1-9 are examples, and Experimental Example 1-10 is a comparative example. (Experimental Example 1-1) (Preparation of Steel Cord) A copper layer and a zinc layer were formed on the surface of a steel filament by plating. For the copper layer, cupric pyrophosphate was used as the plating solution, and the film was formed with a current density of 22 A / dm 2 and a treatment time of 14 seconds. For the zinc layer, zinc sulfate was used as the plating solution, and the film was formed with a current density of 20 A / dm 2 and a treatment time of 7 seconds.

[0180] Thereafter, heat treatment was performed by heating at 600 °C for 9 seconds in an air atmosphere to diffuse the metal components and form a plating film.

[0181] The wire drawing process was performed on the obtained filament with the plating film to make the cord diameter 1 mm.

[0182] Next, the drawn steel cord was cut at a plurality of locations in the longitudinal direction so as to fit the size of the rubber composite to be manufactured. The obtained steel cord has a second coating 1122 that covers the side 11B side and is derived from the plating film of the above filament. When the second coating 1122 was analyzed by SEM-EDX, it was confirmed that it contains Cu and Zn.

[0183] A part of the obtained steel cord was used for the production of the following rubber composite, and the remainder was used for the production of the steel cord described later. (Preparation of Rubber Composition) A rubber composition containing a rubber component and an additive was prepared. The rubber composition contains 100 parts by mass of natural rubber as the rubber component. And the rubber composition contains, as additives, 60 parts by mass of carbon black, 6 parts by mass of sulfur, 1 part by mass of a vulcanization accelerator, 10 parts by mass of zinc oxide, and 1 part by mass of cobalt stearate as an organic acid cobalt, based on 100 parts by mass of the rubber component. (Manufacture of Rubber Composite) Using the above steel cord and the rubber composition, the rubber composite 10 shown in FIGS. 1 and 2 was manufactured.

[0184] The steel cords 11 were arranged so that their longitudinal directions were parallel to each other, and the side surfaces 11B of the steel cords 11 were covered with the rubber composition to produce a precursor of the rubber composite. At this time, the longitudinal end faces 11A of the steel cords 11 were left exposed without being covered with the rubber composition.

[0185] A resin mask with a thickness of 15 μm was placed on the side of the precursor of the rubber composite on the longitudinal end face 11A side of the steel cord 11 to protect the rubber composition. The resin mask has an opening at a position corresponding to the longitudinal end face 11A of the steel cord 11, and the end face 11A is exposed without being covered by the resin mask.

[0186] Next, pretreatment was performed on the exposed longitudinal end face 11A of the steel cord 11.

[0187] The pretreatment was carried out by sequentially performing electrolytic degreasing with 20% by mass sulfuric acid, water washing, electrolytic degreasing with 10% by mass sodium hydroxide aqueous solution, water washing, immersion in 1% by mass sulfuric acid, and water washing. The electrolytic degreasing with 20% by mass sulfuric acid was carried out at a liquid temperature of 45 °C with a current density of 10 A / dm 2 for 1 second. The electrolytic degreasing with 10% by mass sodium hydroxide was carried out at a liquid temperature of 40 °C with a current density of 10 A / dm 2 for 1 second. The immersion in 1% by mass sulfuric acid was carried out at a liquid temperature of 35 °C for 1 second.

[0188] Then, a first coating film 1121 was formed on the longitudinal end face 11A of the steel cord 11 by a coating method. Specifically, conductive copper nanoink (model number GO-01) manufactured by Ishihara Chemical Co., Ltd. was applied to the entire longitudinal end face 11A of the steel cord 11 and dried to form a first coating film 1121 with a thickness of 0.15 μm.

[0189] Note that the first coating film 1121 was formed on the end faces 11A on both sides in the longitudinal direction of all the steel cords 11 included in the rubber composite under the same conditions. Further, when the average thickness of the first coating film 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0190] The average thickness of the first coating film 1121 was measured using a fluorescent X-ray film thickness gauge. The thickness was measured at a total of three points, namely, the center of the end face 11A of the steel cord 11 and two measurement points on the line segment passing through the center, and the average value was taken as the average thickness of the first coating film 1121.

[0191] The line segment passing through the center of the end face 11A of the steel cord 11 is the diameter of the circle that is the contour line of the end face 11A. And when the diameter of the circle that is the contour line of the end face 11A is D, the two measurement points are two points at a distance of 0.25D from the center on the line segment that is the diameter of the circle that is the contour line of the end face 11A and is arbitrarily drawn so as to pass over the first coating film 1121 on the end face 11A. In the following other experimental examples, the average thickness of the first coating film 1121 was measured in the same manner.

[0192] After applying and drying the above-mentioned conductive copper nanoink, the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the side of the longitudinal end face 11A of the steel cord 11 of the precursor of the rubber composite.

[0193] Thereafter, vulcanization was carried out under the conditions of 180°C for 10 minutes to obtain the rubber composite 10. In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first coating 131 containing Cu and S was arranged on the longitudinal end face 11A of the steel cord 11. A second coating 132 containing Cu, Zn, and S was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively.

[0194] The fact that the first coating 131 contains Cu and S and the second coating 132 contains Cu, Zn, and S was confirmed by analysis using SEM-EDX. The same analysis was carried out in the following Experimental Examples 1-2 to 1-10 to identify the contained components. In the following other experimental examples as well, since the second coating 132 contains Cu, Zn, and S, the description is omitted. Also, in the following Experimental Examples 1-2 to 1-9, Experimental Example 2, and Experimental Example 3, both the first coating 131 and the second coating 132 contain at least Cu and S, and it can be said that they contain a copper-sulfur compound.

[0195] Using the obtained rubber composite 10, the corrosion resistance of the rubber composite was evaluated. The evaluation results are shown in Table 1.

[0196] As shown in the evaluation results, when the end-face-side rubber 121 was peeled off to evaluate the corrosion resistance of the longitudinal end face 11A side of the steel cord 11, it was confirmed that the rubber 12 remained. Therefore, as described above, it can be said that the end face 11A of the steel cord 11 is adhered to the rubber 12 via the first coating 131. Similarly, when the rubber was peeled off for the side face 11B side of the steel cord 11, it was confirmed that the rubber 12 remained on the side face 11B of the steel cord 11. Therefore, it can be said that the side face 11B of the steel cord 11 is adhered to the rubber 12 via the second coating 132.

[0197] For the same reasons, regarding the following Experimental Examples 1-2 to 1-9, it was confirmed that the end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively. (Manufacture of Steel Cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing the pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, the first film 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first film 1121 contained Cu. Also, the average thickness of the first film 1121 was 0.15 μm.

[0198] When evaluating the corrosion resistance of the obtained steel cord, the current was less than 10 mA / cm 2 and less. (Experimental Example 1-2) (Manufacture of Rubber Composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that the first film 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by electroplating under the following conditions.

[0199] In this experimental example, the first film 1121 is a laminated film in which a Cu layer and a Sn layer are laminated in this order on the end face 11A, and the first film 1121 was formed so that the total film thickness of the Cu layer and the Sn layer was 0.15 μm. When measuring the average thickness of the first film 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that it was 0.15 μm.

[0200] The Cu layer was formed using a Cu plating solution that is a pyrophosphate bath. The Sn layer was formed using a Sn plating solution that is a sulfuric acid bath. When forming each layer, an electrode with a sponge impregnated with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first film 1121 was to be formed, and power was supplied from the end face opposite to the longitudinal end face 11A of the steel cord 11 on which the first film 1121 was to be formed. The thickness of the first film 1121 was adjusted by the amount of electricity supplied.

[0201] After forming the first coating 1121, it was washed with water and dried, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the end face 11A side in the longitudinal direction of the steel cord 11 of the precursor of the rubber composite, and vulcanized under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0202] In the obtained rubber composite 10, the rubber 12 was disposed so as to cover the entire surface of the steel cord 11. A first coating 131 containing Cu, Sn, and S was disposed on the end face 11A in the longitudinal direction of the steel cord 11. A second coating 132 was disposed on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 1. (Manufacture of Steel Cord) Regarding the end face 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu and Sn. Further, the average thickness of the first coating 1121 was 0.15 μm.

[0203] When the corrosion resistance of the obtained steel cord was evaluated, the current was less than 10 mA / cm 2 less than. (Experimental Example 1-3) (Manufacture of Rubber Composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that the first coating 1121 was formed on the entire end face 11A in the longitudinal direction of the steel cord 11 by electroplating under the following conditions.

[0204] In this experimental example, the first coating 1121 is a laminated film in which a Cu layer, a Zn layer, and a Cu layer are laminated in this order on the end face 11A. The thickness ratio of the Cu layer:Zn layer:Cu layer is 3:4:3, and the first coating 1121 was formed so that the total thickness was 0.15 μm. When measuring the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed to be 0.15 μm.

[0205] The Cu layer was formed using a Cu plating solution that is a pyrophosphate bath. The Zn layer was formed using a Zn plating solution that is a borofluoride bath. When forming each layer, an electrode with a sponge impregnated with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was formed, and power was supplied from the end face opposite to the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was formed. The thickness of the first coating 1121 was adjusted by the amount of electricity supplied.

[0206] After forming the first coating 1121, it was washed with water and dried, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also arranged on the longitudinal end face 11A side of the precursor of the rubber composite, and vulcanized under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0207] In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu, Zn, and S was arranged on the longitudinal end face 11A of the steel cord 11. A second covering 132 was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 1. (Manufacture of steel cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as when manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu and Zn. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0208] When evaluating the corrosion resistance of the obtained steel cord, the current was less than 10 mA / cm 2 and less than. (Experimental Example 1-4) (Manufacture of Rubber Composite) A rubber composite 10 was manufactured and evaluated in the same manner as Experimental Example 1-1, except that the first coating 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by electroplating under the following conditions.

[0209] In this experimental example, the first coating 1121 is a laminated film in which a Cu layer and a Zn layer are laminated in order on the end face 11A, and the thickness ratio of the Cu layer:Zn layer = 6:4. The first coating 1121 was formed so that the total thickness was 0.15 μm. When measuring the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that it was 0.15 μm.

[0210] The Cu layer was formed using a Cu plating solution that is a pyrophosphate bath. The Zn layer was formed using a Zn plating solution that is a fluoborate bath. When forming each layer, a sponge electrode impregnated with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed, and power was supplied from the end face opposite to the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. The thickness of the first coating 1121 was adjusted by the amount of electricity supplied.

[0211] After forming the first coating 1121, it was washed with water and dried, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the end face 11A side in the longitudinal direction of the steel cord 11 of the precursor of the rubber composite, and vulcanized under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0212] In the obtained rubber composite 10, the rubber 12 was disposed so as to cover the entire surface of the steel cord 11. A first coating 131 containing Cu, Zn, and S was disposed on the end face 11A in the longitudinal direction of the steel cord 11. A second coating 132 was disposed on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 1. (Manufacture of Steel Cord) Regarding the end face 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing the same pretreatment as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu and Zn. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0213] When the corrosion resistance of the obtained steel cord was evaluated, the current was less than 10 mA / cm 2 less. (Experimental Example 1-5) (Manufacture of Rubber Composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that the first coating 1121 was formed on the entire end face 11A in the longitudinal direction of the steel cord 11 by electroplating under the following conditions.

[0214] In this experimental example, the first coating 1121 was a Cu layer, and the first coating 1121 was formed so that the film thickness was 0.15 μm. When the average thickness of the first coating 1121 formed on the end face 11A in the longitudinal direction of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0215] The Cu layer, which is the first coating 1121, was formed using a Cu plating solution in a pyrophosphate bath. When forming the Cu layer, an electrode with a sponge soaked with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed, and power was supplied from the surface opposite to the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. The thickness of the first coating 1121 was adjusted according to the amount of electricity supplied.

[0216] After forming the first coating 1121, it was washed with water and dried, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also placed on the side of the longitudinal end face 11A of the steel cord of the precursor of the rubber composite, and vulcanized under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0217] In the obtained rubber composite 10, rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu and S was arranged on the longitudinal end face 11A of the steel cord 11. A second covering 132 was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 1. (Manufacture of steel cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0218] When evaluating the corrosion resistance of the obtained steel cord, the current was less than 10 mA / cm 2 less than that. (Experimental Example 1-6) (Manufacture of rubber composite) A rubber composite 10 was produced and evaluated in the same manner as in Experimental Example 1-1, except that a first coating 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by displacement plating under the following conditions.

[0219] In this experimental example, the first coating 1121 was a Cu layer, and the first coating 1121 was formed so that the film thickness was 0.15 μm. When the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0220] The first coating 1121 was formed by immersing the longitudinal end face of the steel cord 11 in a sulfuric acid bath adjusted to have 0.01 mol / dm 3 for 1 minute, followed by washing with water and drying.

[0221] After forming the first coating 1121, the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the longitudinal end face 11A side of the precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0222] In the obtained rubber composite 10, the rubber 12 was disposed so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu and S was disposed on the longitudinal end face 11A of the steel cord 11. A second covering 132 was disposed on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 1. (Manufacture of Steel Cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, the first coating 1121 was confirmed to contain Cu. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0223] When the corrosion resistance of the obtained steel cord was evaluated, the current was less than 10 mA / cm 2 . (Experimental Example 1-7) (Manufacture of rubber composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that a first coating 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by electroplating under the following conditions.

[0224] In this experimental example, the first coating 1121 is a Cu-Zn alloy layer, and the first coating 1121 was formed so that the film thickness was 0.15 μm. When the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0225] The Cu-Zn alloy layer, which is the first coating 1121, was formed using a plating solution in which zinc sulfate and L-histidine monohydrochloride monohydrate, which is an additive, were added to a pyrophosphate bath for copper plating. The Cu-Zn alloy layer was formed so that the content ratio of Cu and Zn was Cu:Zn = 6:4 in molar ratio. When forming the Cu-Zn alloy layer, a sponge electrode impregnated with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. Then, power was supplied from the surface opposite to the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. The thickness of the first coating 1121 was adjusted by the amount of electricity supplied.

[0226] After forming the first coating 1121, washing with water and drying were performed, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the longitudinal end face 11A side of the precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0227] In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first coating 131 containing Cu, Zn, and S was arranged on the longitudinal end face 11A of the steel cord 11. A second coating 132 was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 1. (Manufacture of steel cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, a first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu and Zn. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0228] When the corrosion resistance of the obtained steel cord was evaluated, the current was less than 10 mA / cm 2 and less. (Experimental Example 1-8) (Manufacture of rubber composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that a first coating 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by electroplating under the following conditions.

[0229] In this experimental example, the first coating 1121 was a Cu-Sn alloy layer, and the first coating 1121 was formed so that the film thickness was 0.15 μm. When the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that the thickness was 0.15 μm.

[0230] The Cu-Sn alloy layer, which is the first coating 1121, was formed using a plating solution prepared by adding stannous sulfate and L-histidine monohydrochloride monohydrate, which is an additive, to a pyrophosphate bath for copper plating. The Cu-Sn alloy layer was formed such that the content ratio of Cu and Sn was Cu:Sn = 95:5 in terms of molar ratio. When forming the Cu-Sn alloy layer, a sponge electrode impregnated with the plating solution was brought into contact with the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. Then, power supply was carried out from the surface opposite to the longitudinal end face 11A of the steel cord 11 on which the first coating 1121 was to be formed. The thickness of the first coating 1121 was adjusted according to the amount of electricity supplied.

[0231] After forming the first coating 1121, it was washed with water and dried, and then the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the longitudinal end face 11A side of the steel cord of the precursor of the rubber composite, and vulcanization was carried out under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0232] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of the steel cord 11. A first coating 131 containing Cu, Sn, and S was disposed on the longitudinal end face 11A of the steel cord 11. A second coating 132 was disposed on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 1. (Manufacture of steel cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing pretreatment in the same manner as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When the first coating 1121 was analyzed by SEM-EDX, it was confirmed that it contained Cu and Sn. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0233] When the corrosion resistance of the obtained steel cord was evaluated, the current was less than 10 mA / cm 2 and less. (Experimental Example 1-9) (Manufacture of Rubber Composite) A rubber composite 10 was manufactured and evaluated in the same manner as in Experimental Example 1-1, except that a first coating 1121 was formed on the entire longitudinal end face 11A of the steel cord 11 by displacement plating under the following conditions.

[0234] In this experimental example, the first coating 1121 was a Cu-Sn alloy layer, and the first coating 1121 was formed so that the film thickness was 0.15 μm. When the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0235] The Cu-Sn alloy layer as the first coating 1121 was formed by immersing the longitudinal end face of the steel cord 11 in a sulfuric acid bath containing copper and tin for 20 seconds, followed by water washing and drying. The Cu-Sn alloy layer was formed so that the content ratio of Cu and Sn was Cu:Sn = 95:5 in molar ratio.

[0236] After forming the first coating 1121, the resin mask that had been protecting the rubber composition was peeled off. Then, the rubber composition was also disposed on the longitudinal end face 11A side of the precursor of the rubber composite, and vulcanization was carried out under the same conditions as in the case of Experimental Example 1-1 to obtain a rubber composite 10.

[0237] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu, Sn, and S was disposed on the longitudinal end face 11A of the steel cord 11. A second covering 132 was disposed on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 1. (Manufacture of Steel Cord) Regarding the longitudinal end face 11A of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, after performing the same pretreatment as in the case of manufacturing the rubber composite in this experimental example, the first coating 1121 was formed. When analyzed by SEM-EDX, it was confirmed that the first coating 1121 contained Cu and Sn. Also, the average thickness of the first coating 1121 was 0.15 μm.

[0238] When evaluating the corrosion resistance of the obtained steel cord, the current was 10 mA / cm 2 less than. (Experimental Example 1-10) (Manufacture of Rubber Composite) When manufacturing the steel cord, the drawn steel cord was cut at a plurality of locations in the longitudinal direction so as to match the size of the rubber composite to be manufactured, and the first coating 1121 was not formed on the end faces, and it was used in a state where the wire 111 was exposed. A rubber composite was produced in the same manner as in Experimental Example 1-1 except for the above points.

[0239] In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A second covering 132 was arranged on the side face 11B of the steel cord 11, but the first covering was not formed on the longitudinal end face 11A of the steel cord 11. The evaluation results are shown in Table 1. (Manufacture of Steel Cord) When evaluating the corrosion resistance of the steel cord obtained in the preparation of the steel cord of Experimental Example 1-1, the current was 10 mA / cm 2 was.

[0240]

Table 1

[0241] Also, in Experimental Examples 1-1 to 1-9, after the damp heat evaluation, the rubber remaining on the end face 11A was peeled off, and the state of the end face 11A was visually confirmed. As a result, it was confirmed that the portion where the rubber remained when the end face side rubber 121 was peeled off for the damp heat evaluation was not discolored. That is, it was also confirmed that the portion where the first coating 131 was formed was protected and corrosion was prevented.

[0242] In contrast, in Experimental Example 1-10, when the damp heat evaluation was performed, almost no rubber remained on the end face 11A, and since the first coating 131 was not formed, it was confirmed that the entire end face 11A was discolored and corrosion was progressing.

[0243] From the above results, it was confirmed that by providing a coating on the end face in the longitudinal direction of the steel cord, a coating was formed on the end face in the longitudinal direction of the steel cord when it was made into a rubber composite, and the corrosion resistance was improved.

[0244] Also, regarding the steel cord, even when it was not made into a rubber composite, it was confirmed that the corrosion resistance could be improved by providing a coating on the end face in the longitudinal direction as in Experimental Examples 1-1 to 1-9. [Experimental Example 2] A rubber composite was produced according to the following procedure, and the corrosion resistance was evaluated. Experimental Examples 2-1 to 2-5 are all examples. (Experimental Example 2-1) When forming the first coating film 1121 on the entire longitudinal end face 11A of the steel cord 11 included in the precursor of the rubber composite by the coating method, a conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the dried first coating film 1121 would be 0.05 μm. When measuring the average thickness of the first coating film 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that it was 0.05 μm.

[0245] Except for the above points, a rubber composite was produced in the same manner as in Experimental Example 1-1.

[0246] In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu and S was arranged on the longitudinal end face 11A of the steel cord 11. A second covering 132 was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 2.

[0247] The fact that the first covering 131 contains Cu and S was confirmed by analysis using SEM-EDX. The same analysis was performed in the following Experimental Examples 2-2 to 2-5 and Experimental Example 3 to identify the contained components. (Experimental Example 2-2) When forming the first coating film 1121 on the entire longitudinal end face 11A of the steel cord 11 included in the precursor of the rubber composite by the coating method, a conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the dried first coating film 1121 would be 0.1 μm. When measuring the average thickness of the first coating film 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that it was 0.1 μm.

[0248] Except for the above points, a rubber composite was produced in the same manner as in Experimental Example 1-1.

[0249] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 2. (Experimental Example 2-3) When forming the first film 1121 on the entire longitudinal end face 11A of the steel cord 11 contained in the precursor of the rubber composite by the coating method, the conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the obtained first film 1121 after drying would be 0.5 μm. In addition, when measuring the average thickness of the first film 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that the thickness was 0.5 μm.

[0250] A rubber composite was produced in the same manner as in Experimental Example 1-1 except for the above points.

[0251] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 2. (Experimental Example 2-4) When forming the first film 1121 on the entire longitudinal end face 11A of the steel cord 11 contained in the precursor of the rubber composite by the coating method, the conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the obtained first film 1121 after drying would be 1 μm. In addition, when measuring the average thickness of the first film 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that the thickness was 1 μm.

[0252] Except for the above points, a rubber composite was produced in the same manner as in Experimental Example 1-1.

[0253] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 2. (Experimental Example 2-5) When forming the first coating 1121 on the entire longitudinal end face 11A of steel cord 11 included in the precursor of the rubber composite by the coating method, the conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the obtained first coating 1121 after drying would be 2 μm. When measuring the average thickness of the first coating 1121 formed on the longitudinal end face 11A of steel cord 11, it was confirmed that it was 2 μm.

[0254] Except for the above points, a rubber composite was produced in the same manner as in Experimental Example 1-1.

[0255] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 2.

[0256]

Table 2

[0257] However, it was confirmed that when the thickness of the first coating exceeded a certain thickness as in Experimental Examples 2-4 and 2-5, the corrosion resistance tended to decrease. This is presumably because a porous reaction layer with S (sulfur) in the rubber was formed. [Experimental Example 3] A rubber composite was produced according to the following procedure and its corrosion resistance was evaluated. All of Experimental Examples 3-1 to 3-3 are examples. (Experimental Example 3-1) When forming the first coating 1121 on the longitudinal end face 11A of the steel cord 11 included in the precursor of the rubber composite by the coating method, the conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the obtained first coating 1121 after drying would be 0.15 μm.

[0258] However, when applying the above coating liquid to the longitudinal end face 11A of the steel cord 11, a part of the longitudinal end face 11A of the steel cord 11 was masked so that the ratio of the area of the region to which the coating liquid was applied in the above end face would be 20%. When the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11 was measured, it was confirmed that it was 0.15 μm.

[0259] A rubber composite was produced in the same manner as in Experimental Example 1-1 except for the above points.

[0260] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 3. (Experimental Example 3-2) When forming the first coating 1121 on the longitudinal end face 11A of steel cord 11 included in the precursor of the rubber composite by a coating method, the conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the obtained first coating 1121 after drying would be 0.15 μm.

[0261] However, when applying the above coating liquid to the longitudinal end face 11A of steel cord 11, a part of the longitudinal end face 11A of steel cord 11 was masked so that the ratio of the area of the region to which the above coating liquid was applied would be 60% of the above end face. When measuring the average thickness of the first coating 1121 formed on the longitudinal end face 11A of steel cord 11, it was confirmed that the thickness was 0.15 μm.

[0262] A rubber composite was produced in the same manner as in Experimental Example 1-1 except for the above points.

[0263] In the obtained rubber composite 10, rubber 12 was disposed so as to cover the entire surface of steel cord 11. A first coating 131 containing Cu and S was disposed on the longitudinal end face 11A of steel cord 11. A second coating 132 was disposed on the side face 11B of steel cord 11. The end face 11A and the side face 11B of steel cord 11 were adhered to rubber 12 via the first coating 131 and the second coating 132, respectively. The evaluation results are shown in Table 3. (Experimental Example 3-3) When forming the first coating 1121 on the longitudinal end face 11A of the steel cord 11 included in the precursor of the rubber composite by a coating method, conductive copper nanoink, which is the same coating liquid as in Experimental Example 1-1, was applied so that the thickness of the first coating 1121 obtained after drying would be 0.15 μm.

[0264] However, when applying the above coating liquid to the longitudinal end face 11A of the steel cord 11, a part of the longitudinal end face 11A of the steel cord 11 was masked, and the ratio of the area of the region to which the coating liquid was applied in the above end face was set to 80%. In addition, when measuring the average thickness of the first coating 1121 formed on the longitudinal end face 11A of the steel cord 11, it was confirmed that the thickness was 0.15 μm.

[0265] A rubber composite was produced in the same manner as in Experimental Example 1-1 except for the above points.

[0266] In the obtained rubber composite 10, the rubber 12 was arranged so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu and S was arranged on the longitudinal end face 11A of the steel cord 11. A second covering 132 was arranged on the side face 11B of the steel cord 11. The end face 11A and the side face 11B of the steel cord 11 were adhered to the rubber 12 via the first covering 131 and the second covering 132, respectively. The evaluation results are shown in Table 3.

[0267]

Table 3

Explanation of Reference Numerals

[0268] 10 Rubber composite 11 Steel cord 11A End face 11B Side face 111 Wire 112 Coating 1121 First coating 1122 Second coating 12 Rubber 121 Rubber on end face side 13 Coated object 131 First coated object 132 Second coated object X X-axis direction (width direction) Y Y-axis direction (longitudinal direction) Z Z-axis direction (thickness direction) 40 Tire 41 Tread part 42 Sidewall part 43 Bead part 44 Inner liner 45 Carcass (rubber composite) 46 Belt layer (rubber composite) 47 Bead wire

Claims

1. A rubber composite, comprising: a steel cord; and rubber covering at least a part of the surface of the steel cord, wherein a first coating containing Cu is disposed on an end face in the longitudinal direction of the steel cord, and the rubber and the first coating are arranged in this order from the outer surface side of the rubber composite on the end face.

2. The rubber composite according to claim 1, wherein the first coating further contains S.

3. The rubber composite according to claim 1 or 2, wherein the first coating further contains Zn.

4. The rubber composite according to claim 3, wherein the first coating further contains one or more selected from Sn, Cr, Fe, Co, and Ni.

5. The rubber composite according to any one of claims 1 to 4, wherein the end face of the steel cord is covered with the rubber via the first coating.

6. The rubber composite according to any one of claims 1 to 5, wherein the end face of the steel cord is adhered to the rubber via the first coating.

7. The rubber composite according to any one of claims 1 to 6, wherein the first coating covers 20% or more of the end face.

8. The rubber composite according to any one of claims 1 to 7, wherein a second coating containing Cu is disposed on a side surface of the steel cord.

9. A tire comprising the rubber composite according to any one of claims 1 to 8.

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