CN115244246A

CN115244246A - Rubber composite, tire, steel cord

Info

Publication number: CN115244246A
Application number: CN202080098104.4A
Authority: CN
Inventors: 中岛彻也; 松冈映史; 真岛正利; 小川光靖; 神田良子; 境田英彰
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2020-03-13
Filing date: 2020-12-23
Publication date: 2022-10-25
Anticipated expiration: 2040-12-23
Also published as: CN115244246B; DE112020006889T5; WO2021181821A1; JPWO2021181821A1

Abstract

A rubber composite body comprising a steel cord and a rubber covering at least a part of the surface of the steel cord, wherein a first covering containing Cu is disposed on the longitudinal end face of the steel cord.

Description

Rubber composite, tire, steel cord

Technical Field

The present disclosure relates to a rubber composite, a tire, a steel cord.

The present application claims to incorporate the entire contents of the entire disclosures in japanese application No. 2020-044547, which was filed on 3/13/2020.

Background

For example, patent document 1 discloses a pneumatic steel radial tire having a carcass layer made of a steel cord fabric in which a steel cord is embedded, wherein the surface of a steel wire constituting the steel cord is subjected to predetermined brass plating.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 8-253004

Disclosure of Invention

The rubber composite of the present disclosure has:

a steel cord, and

a rubber covering at least a part of the surface of the steel cord, and

a first covering containing Cu is disposed on an end surface of the steel cord in the longitudinal direction.

Drawings

Fig. 1 is a perspective view of a rubber composite according to an embodiment of the present disclosure.

FIG. 2 isbase:Sub>A sectional view taken along line A-A' of FIG. 1.

Fig. 3 is an explanatory view of a method of calculating a coverage ratio of an end face of a steel cord in a longitudinal direction by a cover.

Fig. 4 is a cross-sectional view of a tire according to an embodiment of the present disclosure.

Fig. 5 is a cross-sectional view of a steel cord according to an embodiment of the present disclosure.

Detailed Description

[ problems to be solved by the present disclosure ]

In a product including a rubber composite such as a tire, corrosion may occur in the vicinity of an end surface of a steel cord. In recent years, improvement in durability has been required in order to suppress the frequency of replacement of a product including a rubber composite. Therefore, it is required to suppress corrosion in the vicinity of the end face of the steel cord.

Accordingly, an object is to provide a rubber composite in which the end surface corrosion of a steel cord is suppressed.

[ Effect of the present disclosure ]

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

[ description of embodiments of the present disclosure ]

First, embodiments of the present disclosure are listed and explained. 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.

(1) A rubber composite according to one embodiment of the present disclosure includes:

a steel cord, and

a rubber covering at least a part of the surface of the steel cord, and

In the rubber composite according to one embodiment of the present disclosure, the first coating is provided on the end surface of the steel cord in the longitudinal direction, whereby the corrosion resistance of the end surface of the steel cord can be improved.

The first coating contains Cu (copper), whereby the surface (specifically, the end surface in the longitudinal direction) of the steel cord can be protected and the corrosion resistance can be improved.

(2) The first cover may further comprise S.

By further containing S (sulfur) in the first cover, cu is formed with the above-mentioned Cu ₂ The copper-sulfur compound such as S can protect particularly the end face in the longitudinal direction of the steel cord and can improve particularly the corrosion resistance. In addition, the steel curtainCu in the case where the wire and the rubber are bonded via the first cover ₂ The copper-sulfur compound such as S can improve the adhesion between the steel cord and the rubber, and can particularly improve the durability of the rubber composite.

(3) The first cover may further include Zn.

Zn (zinc) promotes the reaction of Cu with other elements contained in the rubber, and promotes Cu ₂ S, etc. in the presence of a copper compound. The copper compound can protect particularly the end face of the steel cord in the longitudinal direction and further improve the corrosion resistance. In addition, when the steel cord and the rubber are bonded through the first cover, the copper compound improves the adhesion between the steel cord and the rubber, and improves the durability of the rubber composite.

(4) The first cover may further contain one or more selected from Sn, cr, fe, co, and Ni.

Sn (tin), cr (chromium), fe (iron), co (cobalt), and Ni (nickel) have a greater ionization tendency than Zn. Therefore, the first coating material contains Cu and Zn and at least one selected from Sn, cr, fe, co, and Ni, thereby functioning as sacrificial corrosion protection or increasing the synthetic potential (synthetic potential) of Cu and Zn. Therefore, the end faces of the steel cord in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

(5) The end face of the steel cord may be covered with the rubber through the first cover.

The longitudinal end face of the steel cord can be protected by rubber in addition to the first cover by covering the longitudinal end face of the steel cord with rubber through the first cover. Therefore, the corrosion resistance of the end faces of the steel cord in the longitudinal direction can be improved. In addition, the rubber composite can be prevented from being damaged, and the durability can be improved.

(6) The end surface of the steel cord may be bonded to the rubber through the first cover.

The longitudinal end face of the steel cord can be protected by rubber in addition to the first cover by adhering the longitudinal end face of the steel cord to rubber through the first cover. Therefore, the corrosion resistance of the end face of the steel cord in the longitudinal direction can be improved.

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 rubber and the end face of the steel cord in the longitudinal direction. However, by bonding the longitudinal end face of the steel cord to the rubber through the first cover, the rubber, the first cover, and the steel cord are integrated and can support the applied force. Therefore, breakage of the rubber composite is particularly suppressed, and durability can be improved.

Further, by bonding the longitudinal end face of the steel cord, the first cover and the rubber, it is possible to prevent particularly the intrusion of foreign matter such as water between the members. Therefore, it is possible to suppress the entry of foreign matter such as water into the end face of the steel cord, and particularly to improve the corrosion resistance.

(7) The first cover may cover more than 20% of the end face.

The first coating covers 20% or more of the area of the end face of the steel cord 11 in the longitudinal direction, and thus the corrosion resistance of the end face of the steel cord can be particularly improved.

(8) A second cover comprising Cu may be arranged on the side of the steel cord.

By providing the rubber composite with the second coating on the side surface of the steel cord, the corrosion resistance of the side surface of the steel cord can be improved.

The second coating contains Cu, whereby the surface (specifically, the side surface) of the steel cord can be protected and the corrosion resistance can be improved.

(9) A tire according to one embodiment of the present disclosure includes the rubber composite according to any one of (1) to (8).

A tire according to one embodiment of the present disclosure includes the rubber composite. Therefore, corrosion of the end faces of the steel cord in the longitudinal direction can be suppressed, and the durability can be improved.

(10) In a steel cord according to one embodiment of the present disclosure, a coating film containing Cu is disposed on an end surface in a longitudinal direction.

The steel cord according to one embodiment of the present disclosure has a coating on an end surface in a longitudinal direction, and thus can improve corrosion resistance of the end surface.

The coating film contains Cu (copper), whereby the surface of the steel cord can be protected and the corrosion resistance can be improved.

(11) The coating may further contain Zn.

Zn has a greater ionization tendency than Cu. Therefore, the coating film can function as sacrificial corrosion protection by including Zn in addition to Cu. Therefore, the end faces of the steel cord in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

(12) The coating may further contain one or more selected from Sn, cr, fe, co, and Ni.

Sn, cr, fe, co and Ni have a higher ionization tendency than Zn. Therefore, the film contains Cu and Zn and at least one selected from Sn, cr, fe, co, and Ni, and thus can function as sacrificial corrosion protection or increase the synthetic potential of Cu and Zn. Therefore, the end faces of the steel cord in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

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

The coating film covers 20% or more of the area of the end face of the steel cord 11 in the longitudinal direction, and thereby the corrosion resistance of the end face of the steel cord can be particularly improved.

[ details of embodiments of the present disclosure ]

Specific examples of a rubber composite, a tire, and a steel cord according to an embodiment (hereinafter referred to as "the present embodiment") of the present disclosure will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and range equivalent to the claims.

[ rubber composite ]

In a product including a rubber composite such as a tire, corrosion may occur in the vicinity of an end surface of a steel cord. In order to suppress the occurrence of this corrosion, the inventors of the present invention have studied the cause of the corrosion.

As described above, conventionally, a coating film obtained by plating has been formed on the surface of a wire of a steel cord.

When a rubber composite is produced using a steel cord having a coating film, a metal component contained in the coating film of the steel cord reacts with a component of rubber to form a coating also called an adhesive layer on the surface of the steel cord. It is considered that the steel cord is protected and the corrosion resistance is improved by forming the covering on the surface of the steel cord.

However, in the production of the rubber composite, the steel cord needs to be cut in accordance with the size of the rubber composite. Therefore, the wire members are exposed at the end faces of the steel cord contained in the rubber composite, and no covering is formed on the end faces of the steel cord. As a result, it is considered that in the conventional rubber composite, the end face of the steel cord is not protected, and corrosion occurs at the end face.

Based on the above results of the study, the inventors of the present invention completed the rubber composite of the present embodiment capable of suppressing corrosion at the end face of the steel cord.

Fig. 1 and 2 show an example of the structure of the rubber composite of the present embodiment. Fig. 1 isbase:Sub>A perspective view ofbase:Sub>A rubber composite 10 according to the present embodiment, and fig. 2 isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A' of fig. 1, specifically,base:Sub>A sectional view taken alongbase:Sub>A plane passing through the center axis ofbase:Sub>A steel cord 11 at the end in the longitudinal direction of the steel cord 11. In fig. 1 and 2, the Y-axis direction is a direction 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 fig. 1 and 2, the X-axis direction is the width direction of the rubber composite 10, and a plurality of steel cords 11 are aligned in a row in the X-axis direction. The Z-axis direction is the thickness direction of the rubber composite 10.

As shown in fig. 1, the rubber composite 10 of the present embodiment may have a steel cord 11 and a rubber 12 covering at least a part of the surface of the steel cord 11. Further, as shown in fig. 2, a first cover 131 as the cover 13 may be provided at the end surface 11A in the longitudinal direction of the steel cord 11.

The number of the steel cords 11 included in the rubber composite 10 of the present embodiment is not particularly limited, and may be selected according to the application, and may be, for example, one or a plurality of cords. 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, and for example, as shown in fig. 1, the steel cords 11 may be arranged in a line on an XZ plane which is a cross section perpendicular to the longitudinal direction of the plurality of steel cords 11.

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 may have a wire 111 and a coating film 112 covering the surface of the wire 111. Fig. 1 and 2 show an example in which the steel cord 11 is formed of 1 wire, but the present invention is not limited to this embodiment. For example, the steel cord may be a steel cord formed by twisting a plurality of steel wires. When the steel cord has a structure in which a plurality of steel wires are twisted, each steel wire preferably has a wire 111 described below and a coating 112 covering the surface of the wire 111.

The wire 111 of the steel cord 11 may be, for example, a steel wire, and more preferably a high carbon steel wire.

As the coating 112, the steel cord 11 may have a first coating 1121 covering the end surface 11A side in addition to a second coating 1122 covering the side surface 11B side of the steel cord 11.

By providing the coating 112 on the surface of the wire 111 of the steel cord 11, the coating 13 can be formed on the surface of the steel cord 11 when the rubber composite 10 is produced. Specifically, by providing the first coating 1121 that covers the longitudinal end face 11A side of the steel cord 11, the first covering 131 can be formed and arranged on the longitudinal end face 11A of the steel cord 11 when the rubber composite 10 is manufactured.

Further, by providing the second coating 1122 covering the side surface 11B side of the steel cord 11, the second covering 132 can be formed and arranged on the side surface 11B side of the steel cord 11 when the rubber composite 10 is manufactured.

When the rubber composite 10 is manufactured, the first coating 1121 and the second coating 1122 react with rubber components to form the first covering 131 and the second covering 132. Therefore, when the rubber composite 10 is manufactured, a part of the first coating 1121 and the second coating 1122 may remain, or the whole may be the first cover 131 and the second cover 132. That is, the rubber composite 10 may not have the first coating 1121 and the second coating 1122.

As described above, in the production of the rubber composite, the steel cord needs to be cut in accordance with the size of the rubber composite. Therefore, in the conventional rubber composite, no coating is provided on the end surface of the steel cord in the longitudinal direction. Further, it is considered that the covering is formed by a reaction of a rubber component and a component of a coating film of the steel cord. Therefore, when the end face of the steel cord in the longitudinal direction is not coated, the end face is not coated, and corrosion occurs from the end face of the steel cord in the longitudinal direction in the conventional rubber composite.

On the other hand, the steel cord 11 included in the rubber composite 10 of the present embodiment includes a first coating 1121 as a coating 112 on the end surface 11A in the longitudinal direction. Therefore, the rubber composite 10 can have the first coating 131 on the end surface of the steel cord 11 in the longitudinal direction, and the corrosion resistance of the end surface 11A of the steel cord can be improved.

The steel cord 11 included in the rubber composite 10 of the present embodiment may include the second coating 1122 as the coating 112 on the side surface 11B. Therefore, the rubber composite 10 may have the second cover 132 on the side surface of the steel cord 11, and the corrosion resistance of the side surface 11B of the steel cord may be improved.

In order to manufacture the rubber composite 10, the first coating 1121 may be formed after cutting a steel cord into a predetermined length. Specifically, the rubber layer may be formed before the steel cord 11 is embedded in the rubber 12, or after a part of the steel cord 11 is embedded in the rubber 12 and before the longitudinal end face of the steel cord 11 is covered with the rubber 12 or the like.

A specific method of forming the first coating film 1121 is not particularly limited, and various methods capable of forming a coating film having a desired composition can be used. The first coating film 1121 may contain, for example, one or more selected from the group consisting of an oxide and a metal. Therefore, the first film 1121 may be formed by various methods capable of forming an oxide or a metal. Examples of the method for producing the first coating 1121 include a coating method in which a coating solution containing a predetermined component such as a metal is applied, and a dipping method in which the end surface 11A side of the steel cord 11 is dipped in the coating solution. Examples of the method for manufacturing the first coating 1121 include, in addition to electroplating, electroless plating, and displacement plating. The plating method may be brush plating or the like. When the first film 1121 includes a plurality of components, a plurality of layers corresponding to the plurality of components of the first film 1121 may be formed on the end surfaces of the steel cord 11 in the longitudinal direction, and heat treatment may be performed as necessary to form the first film 1121. Before the first coating 1121 is formed, the end surfaces 11A of the steel cords 11 are preferably subjected to a pretreatment such as degreasing treatment to remove substances adhering to the surfaces, but the first coating 1121 may be formed without the pretreatment.

The method of forming the second coating 1122 is not particularly limited, and for example, a coating corresponding to the surface of the bus bar for manufacturing the steel cord 11 is formed in advance, and the bus bar is drawn, whereby 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 a coating formed on the surface of the bus bar before drawing.

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

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

Further, the coating 112 preferably contains at least one selected from Sn (tin), cr (chromium), fe (iron), co (cobalt), and Ni (nickel) in addition to Cu and Zn.

(2) Rubber composition

The rubber 12 can be produced by molding a rubber composition and vulcanizing it as necessary.

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

The rubber component preferably contains at least one selected from natural rubber (NR: natural rubber) and isoprene rubber (IR: isoprene rubber) in an amount of 60% by mass or more, more preferably 70% by mass or more, and still more preferably 100% by mass, in the rubber component.

This is because the ratio of the one or more rubbers selected from natural rubber and isoprene rubber in the rubber component is preferably set to 60 mass% or more, so that the breaking strength of the rubber composite can be improved.

Examples of the rubber component used in combination with the natural rubber and the isoprene rubber include at least one 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).

The sulfur is not particularly limited, and for example, sulfur generally used as a vulcanizing agent in the rubber industry can be used.

The sulfur content of the rubber is not particularly limited, and is preferably set to, 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.

This is because the crosslinking density of the obtained rubber, particularly the adhesion between the steel cord and the rubber, can be increased by setting the ratio of sulfur to 100 parts by mass of the rubber component to 5 parts by mass or more. Further, it is preferable that the ratio of sulfur to 100 parts by mass of the rubber component is set to 8 parts by mass or less because sulfur can be particularly uniformly dispersed in the rubber and the occurrence of blooming (blooming) can be suppressed.

The vulcanization accelerator is not particularly limited, and for example, sulfenamide-based accelerators such as N, N' -dicyclohexyl-2-benzothiazylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide, N-t-butyl-2-benzothiazylsulfenamide and N-oxydiethylene-2-benzothiazylsulfenamide can be preferably used. Further, if necessary, thiazole accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazole disulfide; thiuram accelerators such as tetrabenzylthiuram disulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide and tetramethylthiuram monosulfide.

The rubber composition used in the rubber composite of the present embodiment can be produced by kneading, heating, and extruding the above-described respective components by a conventional method.

The rubber of the rubber composite of the present embodiment preferably contains one or more selected from the group consisting of a cobalt simple substance and a cobalt-containing compound.

Examples of the cobalt-containing compound include cobalt organic acid and cobalt inorganic acid.

As the organic acid cobalt, for example, one or more selected from cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt abietate, cobalt versatate, cobalt tallate, and the like can be preferably used. The organic acid cobalt may be a complex salt obtained by substituting a part of the organic acid with boric acid.

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

In particular, the rubber of the rubber composite of the present embodiment more preferably contains organic acid cobalt. This is because the initial adhesion property between the steel cord and the rubber can be particularly improved by containing the organic acid cobalt. The initial adhesion performance is an adhesion performance between a steel cord and rubber immediately after vulcanization, for example, in the production of a rubber composite.

Further, according to the study of the present inventors, it is possible to increase Cu in the coating by adding cobalt to the rubber ₂ S and the like, and can improve the adhesive force between the steel cord and the rubber. Further, in the case of using cobalt, which is an organic acid, as the added cobalt, this tendency becomes remarkable. Therefore, the rubber of the rubber composite of the present embodiment preferably contains cobalt, particularly an organic compoundCobalt sulfate enables the production of a rubber composite particularly excellent in durability.

In addition, the rubber may contain optional components in addition to the rubber component, sulfur, a vulcanization accelerator, cobalt, and the like. The rubber may further contain known additives for rubbers such as reinforcing agents (carbon black, silica, etc.), waxes, and antioxidants.

The rubber 12 may 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 a portion not directly covered with the rubber 12, the component of the coating 112 can react with the component of the rubber 12 to form the covering 13 in the portion where the coating 112 is provided, and the corrosion resistance can be improved.

Therefore, the rubber 12 may cover at least a part of the end face 11A of the steel cord 11, for example, or may cover the entire end face 11A. The rubber 12 may cover at least a part of the side surface 11B of the steel cord 11, or may cover the entire side surface 11B of the steel cord 11. The rubber 12 may also cover the entire surface of the steel cord 11.

From the viewpoint of protecting the longitudinal end surfaces 11A of the steel cord 11, particularly improving corrosion resistance, the rubber 12 preferably covers at least a part of the longitudinal end surfaces 11A of the steel cord 11, and more preferably covers the entire longitudinal end surfaces 11A of the steel cord 11.

(3) Covering article

(3-1) first cover

As described above, the rubber composite 10 of the present embodiment may have the first cover 131 as the cover 13 on the end surface 11A in the longitudinal direction of the steel cord 11.

Fig. 2 shows an example in which the end face 11A of the first cover 131 in the longitudinal direction of the steel cord 11 is formed with a uniform thickness, but fig. 2 is schematically shown and is not limited thereto. For example, the first cover 131 may be disposed so as to be scattered on the surface of the end surface 11A in the longitudinal direction of the steel cord 11, or may have a film shape so as to cover the entire end surface 11A in the longitudinal direction of the steel cord 11 as shown in fig. 2.

It is considered that the first cover 131 is formed by reacting a component contained in the first coating film 1121 with a component contained in the rubber 12 or the like. Therefore, the composition of the first cover 131 varies depending on the composition of the first coating film 1121, the rubber 12, and is not particularly limited, but the first cover 131 preferably contains Cu (copper), for example. This is because the first cover 131 contains Cu, thereby protecting the surface of the steel cord 11 (specifically, the end surface in the longitudinal direction) and improving corrosion resistance.

As described above, the first film 1121 may further include Zn (zinc) in addition to Cu. The first film 1121 may include Cu and Zn, and may further include one or more selected from Sn (tin), cr (chromium), fe (iron), co (cobalt), and Ni (nickel). Therefore, the first cover 131 may further include Zn in addition to Cu. The first cover 131 may further include one or more selected from Sn, cr, fe, co, and Ni in addition to Cu and Zn.

In the case where the first coating film 1121 includes Zn in addition to Cu, the first cover 131 may include Zn in addition to Cu. Zn promotes the reaction of Cu with other elements contained in the rubber, and promotes Cu ₂ S, etc. in the presence of a copper compound. The copper compound protects the end surface 11A of the steel cord 11 in the longitudinal direction in particular, and can further improve the corrosion resistance. In addition, when the steel cord 11 and the rubber 12 are bonded via the first cover 131, the copper compound improves the adhesion between the steel cord and the rubber, and can improve the durability of the rubber composite.

In addition, sn, cr, fe, co, and Ni have a higher ionization tendency than Zn. Therefore, the first cover 131 includes Cu and Zn, and also includes one or more selected from Sn, cr, fe, co, and Ni, thereby functioning as sacrificial corrosion protection or increasing the composite potential of Cu and Zn. Therefore, the end surfaces 11A of the steel cord 11 in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

In the production of the rubber composite, vulcanization is generally performed. Therefore, the first cover 131 more preferably further contains S (sulfur) added at the time of vulcanization. By the first covering 131 also containing S, andthe Cu forms Cu ₂ S and other copper-sulfur compounds can protect the end surfaces 11A of the steel cord 11 in the longitudinal direction, and particularly improve the corrosion resistance. In addition, in the case where the steel cord 11 and the rubber 12 are bonded via the first cover 131, cu ₂ The copper-sulfur compound such as S can improve the adhesion between the steel cord 11 and the rubber, and particularly improve the durability of the rubber composite.

The first cover 131 may also contain a portion of the composition of the first cover film 1121. As described above, the first coating 1121 may contain one or more selected from the group consisting of oxides and metals. Therefore, the first cover 131 may contain one or more selected from oxides and metals from the first cover film 1121. The first cover 131 contains one or more selected from an oxide and a metal, and thus, the adhesion to the first film 1121 is particularly improved. Therefore, the corrosion resistance of the steel cord 11 can be particularly improved, and the adhesion between the steel cord 11 and the rubber 12 can be improved at the portion where the steel cord 11 and the rubber 12 are adhered.

As described above, in the rubber composite 10 of the present embodiment, the rubber 12 preferably covers at least a part of the longitudinal end surface 11A of the steel cord 11, and more preferably covers the entire longitudinal end surface 11A of the steel cord 11.

In the production of the rubber composite 10, as described above, the rubber 12 is disposed so as to cover at least a part of the longitudinal end surface 11A of the steel cord 11, whereby the longitudinal end surface 11A of the steel cord 11 can be bonded to the rubber 12 via the first cover 131. That is, the rubber 12, the first cover 131, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the longitudinal end surface 11A side of the steel cord 11, and the rubber 12, the first cover 131, and the steel cord 11 can be bonded to each other.

As described above, by bonding the longitudinal end face 11A of the steel cord 11 to the rubber 12 through the first cover 131, the longitudinal end face 11A of the steel cord 11 can be protected by the rubber 12 in addition to the first cover 131. Therefore, the corrosion resistance of the end surface 11A in the longitudinal direction of the steel cord 11 can be improved.

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, the rubber 12, the first cover 131, and the steel cord 11 are integrated to support the applied force by bonding the longitudinal end face 11A of the steel cord 11 to the rubber 12 through the first cover 131. Therefore, breakage of the rubber composite 10 is particularly suppressed, and durability can be improved.

Further, by bonding the longitudinal end face 11A of the steel cord 11, the first cover 131, and the rubber 12, it is possible to prevent particularly foreign matter such as water from entering between the members. Therefore, it is possible to suppress the entry of foreign matter such as water into the end surface 11A in the longitudinal direction of the steel cord 11, and particularly to improve the corrosion resistance.

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 cover 131 and the periphery thereof may change. Further, a force may be repeatedly applied between the rubber 12 and the steel cord 11, and a gap may be formed between the both members. Therefore, when the rubber composite 10 is used for a long period of time, the adhesion between the rubber 12 and the steel cord 11 may be reduced.

However, even when the adhesion between the rubber 12 and the steel cord 11 is reduced, the rubber composite 10 has the effect of protecting the end surface 11A of the steel cord 11 and improving the corrosion resistance because the first covering 131 is disposed on the end surface 11A of the steel cord 11.

Therefore, the longitudinal end face 11A of the steel cord 11 is not limited to the form of being bonded to the rubber 12 through the first cover 131, and the longitudinal end face 11A of the steel cord 11 may be covered with rubber through the first cover.

By covering the longitudinal end surface 11A of the steel cord 11 with the rubber 12 through the first cover, the longitudinal end surface 11A of the steel cord 11 can be protected by the rubber 12 in addition to the first cover 131. Therefore, the corrosion resistance of the end surface 11A in the longitudinal direction of the steel cord 11 can be improved. In addition, the rubber composite 10 can be prevented from being broken, and the durability of the rubber composite 10 can be improved.

The end surface 11A of the steel cord in the longitudinal direction is covered with the rubber 12 via the first cover 131, and the above-described adhesion and the following two modes are included. As a first embodiment, the rubber 12, the first cover 131, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the end surface 11A of the steel cord 11 in the longitudinal direction, and the respective members are in contact with each other. The contact of the members is a state in which the members are in contact with each other without any gap, although there is no adhesive force between the members. As a second form, the rubber 12, the first cover 131, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the longitudinal end surface 11A of the steel cord 11, and a gap is included in at least a part between the respective members.

In any of the embodiments in which the longitudinal end surface 11A of the steel cord 11 is covered with rubber via the first cover 131, the first coating 1121 may be disposed on the surface of the steel cord 11 facing the first cover 131.

As described above, in the conventional rubber composite, the first coating 1121 as the coating 112 is not formed on the end surface 11A side of the steel cord 11, and therefore the first cover 131 is not disposed on the end surface 11A of the steel cord 11. Therefore, if the first cover 131 is disposed even in a small amount on the end face 11A of the steel cord 11, the corrosion resistance can be improved compared to the conventional one, and the degree of disposing the first cover 131 is not particularly limited. However, the first cover 131 preferably covers 20% or more, more preferably 40% or more, of the area of the end face 11A in the longitudinal direction of the steel cord 11. The first cover 131 is preferable because it can particularly improve the corrosion resistance of the end face 11A of the steel cord 11 by covering 20% or more of the area of the end face 11A of the steel cord 11 in the longitudinal direction.

Since the first cover 131 may cover the entire end surface 11A of the steel cord 11, the first cover 131 may cover 100% or less of the area of the end surface 11A of the steel cord 11.

A method of measuring the ratio of the area of the end face 11A of the steel cord 11 covered by the first cover 131 is not particularly limited. For example, when 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 in the rubber composite 10, is peeled off, the end face 11A side of the steel cord 11 is exposed as shown in fig. 3. Therefore, the ratio of the area occupied by the rubber 12 obtained by subtracting the exposed region of the steel cord 11 such as the first coating 1121 from the end surface 11A of the steel cord 11 can be calculated. Since the rubber 12 remaining on the end surface 11A of the steel cord 11 corresponds to the portion where the first cover 131 is formed, the ratio of the area occupied by the rubber 12 can be calculated as described above, as the ratio of the area of the first cover 131 covering the end surface 11A of the steel cord 11.

When the end face side rubber 121 is peeled off, the element distribution map of the end face side rubber 121 and one of the end face 11A sides of the steel cord exposed after peeling may be performed to measure the ratio of the area of the end face 11A of the steel cord 11 covered with the first covering 131. When rubber remains on the end surface 11A side of the steel cord, the element distribution map may be performed on the end surface 11A side of the steel cord, and when rubber does not remain on the end surface 11A side of the steel cord, the element distribution map may be performed on the end surface side rubber 121 side.

In the element distribution mapping, a region where both the component of the first coating film 1121 and the component of rubber, for example, cu and S are distributed becomes a region where the first cover 131 is formed. Therefore, from the result of the element distribution map, the ratio of the area of the end surface 11A of the steel cord 11 covered with the first cover 131 can be calculated by obtaining the ratio of the area of the end surface 11A of the steel cord 11 in which the first cover 131 is formed.

The method for mapping the element distribution is not particularly limited, and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray spectroscopy) or the like can be used. When element mapping is performed on the end-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 cover

The rubber composite 10 may have a second cover 132 as the cover 13 on the side surface 11B side of the steel cord 11. It is considered that the second cover 132 is formed by a reaction of a component contained in the second cover 1122 with a component contained in the rubber 12 or the like. Therefore, the composition of the second cover 132 varies depending on the composition of the second cover 1122 and the rubber 12, and is not particularly limited, but the second cover 132 preferably contains Cu (copper), for example. This is because the second cover 132 containing Cu protects the surface (specifically, the side surface) of the steel cord 11 and improves corrosion resistance.

As described above, the second coating 1122 may further contain Zn (zinc) in addition to Cu. Therefore, the second cover 132 may further include Zn in addition to Cu. Zn promotes the reaction of Cu with other elements contained in the rubber, and promotes Cu ₂ S, etc. The copper compound protects the side surface 11B of the steel cord 11 in particular, and can further improve the corrosion resistance. In addition, when the steel cord 11 and the rubber 12 are bonded via the second cover 132, the copper compound can improve the adhesion between the steel cord and the rubber and improve the durability of the rubber composite.

The second coating 1122 may 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 cover 132 may further include 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 higher ionization tendency than Zn. Therefore, the second cover 132 includes Cu and Zn, and also includes one or more selected from Sn, cr, fe, co, and Ni, thereby functioning as sacrificial corrosion protection or increasing the synthetic potential of Cu and Zn. Therefore, the side surface 11B of the steel cord 11 can be protected, and the corrosion resistance can be further improved.

It is also more preferable for the second cover 132 to further contain S (sulfur) added at the time of vulcanization. By further containing S in the second cover 132, cu can be formed with the above-described Cu ₂ S, and the like. In the case where the steel cord 11 and the rubber 12 are bonded via the second cover 132, the copper-sulfur compound can enhance the adhesion between the steel cord 11 and the rubberThe adhesion between them, particularly, improves the durability of the rubber composite.

As described above, in the rubber composite 10 of the present embodiment, the rubber 12 preferably covers at least a part of the side surface 11B of the steel cord 11, and more preferably covers the entire side surface 11B of the steel cord 11.

In the production of the rubber composite 10, by disposing 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 bonded to the rubber 12 via the second cover 132. That is, the rubber 12, the second cover 132, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the side of the side surface 11B of the steel cord 11, and the rubber 12, the second cover 132, and the steel cord 11 can be bonded to each other.

As described above, by bonding the side surface 11B of the steel cord 11 to the rubber 12 through the second cover 132, the side surface 11B of the steel cord 11 can be protected by the rubber 12 in addition to the second cover 132. Therefore, the corrosion resistance of the side surface 11B of the steel cord 11 can be improved.

When the rubber composite 10 is used for 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, the rubber 12, the second cover 132, and the steel cord 11 are integrated to support the applied force by bonding the side surface 11B of the steel cord 11 to the rubber 12 through the second cover 132. Therefore, breakage of the rubber composite 10 is particularly suppressed, and durability can be improved.

Further, by bonding the side surfaces 11B of the steel cord 11, the second cover 132, and the rubber 12, it is possible to prevent particularly foreign matter such as water from entering between the members. Therefore, it is possible to suppress the intrusion of foreign matter such as water into the side surface 11B of the steel cord 11 and improve the corrosion resistance.

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 second coating 1122 proceeds, and the state of the second coating 132 and its surroundings may change. Further, a force may be repeatedly applied between the rubber 12 and the steel cord 11, and a gap may be formed between the both members. Therefore, when the rubber composite 10 is used for a long period of time, the adhesion between the rubber 12 and the steel cord 11 may be reduced.

However, even when the adhesion between the rubber 12 and the steel cord 11 is reduced, the rubber composite 10 has the effect of protecting the side surface 11B of the steel cord 11 and improving corrosion resistance because the second coating 132 is disposed on the side surface 11B of the steel cord 11.

Therefore, the side surface 11B of the steel cord 11 is not limited to the form of being bonded to the rubber 12 through the second cover 132, and the side surface 11B of the steel cord 11 may be covered with rubber through the second cover.

Since the side surface 11B of the steel cord 11 is covered with the rubber 12 through the second cover, the side surface 11B of the steel cord 11 can be protected by the rubber 12 in addition to the second cover 132. Therefore, the corrosion resistance of the side surface 11B of the steel cord 11 can be improved. In addition, the rubber composite 10 can be prevented from being damaged, and the durability of the rubber composite 10 can be improved.

The side surface 11B of the steel cord is covered with rubber through a second cover, including the above-described case of adhesion and the following two forms. As a first embodiment, the rubber 12, the second cover 132, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the side surface 11B of the steel cord 11, and the respective members are in contact with each other. The contact of the members is a state in which the members are in contact with each other without any gap, although there is no adhesive force between the members. As a second form, the rubber 12, the second cover 132, and the steel cord 11 are arranged in this order from the outer surface side of the rubber composite 10 on the side surface 11B of the steel cord 11, and a gap is included in at least a part between the respective members.

In either case where the side surface 11B of the steel cord 11 is covered with rubber through the second cover 132, the second coating 1122 may be disposed on the surface of the steel cord 11 facing the second cover 132.

[ tires ]

Next, a tire in the present embodiment will be described with reference to fig. 4.

The tire of the present embodiment may contain the above-described rubber composite.

Fig. 4 shows a cross-sectional view of a surface perpendicular to the circumferential direction of the tire 40 according to the present embodiment. In fig. 4, only the left side portion of CL (center line) is shown, but the same structure is continuously provided on the right side of CL with CL as the axis of symmetry.

As shown in fig. 4, the tire 40 has a tread portion 41, a sidewall portion 42, and a bead portion 43.

The tread portion 41 is a portion that contacts the road surface. The bead portion 43 is provided on the inner diameter side of the tire 40 than the tread portion 41. The bead portion 43 is a portion 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 a road surface, the sidewall portion 42 elastically deforms to absorb the impact.

The tire 40 has an inner liner 44, a carcass 45, a belt 46, and a bead wire 47.

The inner liner 44 is made of rubber, and seals a space between the tire 40 and the wheel.

Carcass 45 forms the carcass of tire 40. The carcass 45 is made of organic fibers such as polyester, nylon, or rayon, or steel cords, and rubber. The above-described rubber composite may be used for the carcass 45.

The bead wire 47 is provided to the bead portion 43. The bead wire 47 receives a tensile force applied to the carcass 45.

The belt 46 fastens the carcass 45, and increases the rigidity of the tread portion 41. In the example shown in fig. 4, the tire 40 has 2 belt layers 46.

The 2 belt layers 46 may be stacked in the radial direction of the tire 40, and the above-described rubber composite may be used.

The tire of the present embodiment includes the above-described rubber composite. Therefore, corrosion of the end faces of the steel cord in the longitudinal direction can be suppressed, and durability can be improved.

[ Steel cord ]

The steel cord of the present embodiment may have the same configuration as the steel cord 11 described in the rubber composite. Therefore, a part of the overlapping description is omitted.

Fig. 5 schematically shows a cross-sectional view of a plane passing through the center axis of the steel cord of the present embodiment. In fig. 5, the Y-axis direction is a direction 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.

As shown in fig. 5, the steel cord 11 of the present embodiment may have wires 111 and a coating 112 covering the surfaces of the wires 111. Fig. 5 shows an example of a single-wire steel cord in which the steel cord 11 is composed of 1 wire, but is not limited to the above-described manner. For example, the steel cord may be a steel cord obtained by twisting a plurality of steel wires. When the steel cord has a structure in which a plurality of steel wires are twisted, each steel wire preferably has a wire 111 described below and a coating 112 covering the surface of the wire 111.

The wire 111 of the steel cord 11 may be, for example, a steel wire, and more preferably a high-carbon steel wire.

The steel cord 11 may have a first coating 1121 as the coating 112, which covers the end face of the steel cord 11 in the longitudinal direction. The first coating 1121 may cover the entire surface of the end surface 11A in the longitudinal direction of the steel cord 11, or may cover a part of the end surface 11A.

The steel cord 11 may 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.

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

When a rubber composite or the like is produced using a steel cord, it is necessary to cut the steel cord in accordance with a desired size or the like. Therefore, in the conventional steel cord, no coating is provided on the end surface in the longitudinal direction. In addition, when the end faces of the steel cord in the longitudinal direction are not coated, corrosion occurs from the end faces of the steel cord in the longitudinal direction.

In contrast, the steel cord 11 of the present embodiment has the first coating 1121 covering the end surface 11A side in the longitudinal direction, and thus can particularly improve corrosion resistance.

Further, the steel cord 11 of the present embodiment also has the second coating 1122 covering the side surface 11B side, thereby protecting the side surface 11B and improving corrosion resistance.

To manufacture the rubber composite 10, the first cover 1121 may be formed after cutting a steel cord into a predetermined length. Specifically, it may be formed after cutting the steel cord 11.

A specific method for forming the first coating 1121 is not particularly limited, and various methods capable of forming a coating having a desired composition can be used. The first coating film 1121 may contain, for example, one or more selected from the group consisting of an oxide and a metal. Therefore, the first film 1121 may be formed by various methods capable of forming an oxide or a metal. Since the method of manufacturing the first film 1121 has already been described, the description thereof is omitted here.

The first coating 1121 provided on the end surface 11A side of the steel cord 11 and the second coating 1122 provided on the side surface 11B side are formed at different timings. Therefore, the first coating 1121 and the second coating 1122 may have the same composition or different thicknesses.

The composition of the first coating 1121 and the second coating 1122 as the coating 112 is not particularly limited. The first overcoat film 1121 preferably contains, for example, cu (copper). This is because the first coating 1121 includes Cu to protect the end surface of the steel cord 11 and improve corrosion resistance.

The first coating film 1121 more preferably further includes Zn (zinc) in addition to Cu.

Zn has a greater ionization tendency than Cu. Therefore, the second coating 1122 contains Zn in addition to Cu, and thus can function as sacrificial corrosion protection. Therefore, the end surfaces 11A of the steel cord 11 in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

Further, the second coating 1122 preferably contains at least one selected from Sn (tin), cr (chromium), fe (iron), co (cobalt), and Ni (nickel) in addition to Cu and Zn.

Sn, cr, fe, co and Ni have a higher ionization tendency than Zn. Therefore, the second coating 1122 contains Cu and Zn and at least one selected from Sn, cr, fe, co, and Ni, and thus can function as sacrificial corrosion protection or can increase the combined potential of Cu and Zn. Therefore, the end surfaces 11A of the steel cord 11 in the longitudinal direction can be protected, and the corrosion resistance can be further improved.

The same material as that for the first coating 1121 may also be preferably used for the second coating 1122. That is, the second coating 1122 preferably contains Cu. Further, the second coating 1122 preferably contains Zn in addition to Cu. The second coating 1122 preferably further contains Cu and Zn, and at least one selected from Sn, cr, fe, co, and Ni. The reason is the same as that of the first coating 1121, and therefore, the description thereof is omitted.

In the conventional steel cord, the first coating 1121 as the coating 112 is not formed on the end surface 11A side of the steel cord 11. Therefore, if the first coating 1121 is disposed even in a small amount on the end surface 11A of the steel cord 11, the corrosion resistance can be improved compared to the conventional one, and the degree of disposing the first coating 1121 is not particularly limited. However, the first coating 1121 preferably covers 20% or more, more preferably 40% or more, of the area of the end surface 11A of the steel cord 11 in the longitudinal direction. It is preferable that the first coating 1121 covers 20% or more of the area of the end surface 11A of the steel cord 11 in the longitudinal direction, because the corrosion resistance of the end surface 11A of the steel cord 11 can be particularly improved.

Since the first coating 1121 may cover the entire end surface 11A of the steel cord 11, the first coating 1121 may cover 100% or less of the area of the end surface 11A of the steel cord 11.

A method of measuring the ratio of the area of the first coating 1121 covering the end face 11A of the steel cord 11 is not particularly limited. The evaluation can be performed in the same manner as in the case of the first cover.

That is, for example, the rubber composite 10 is first formed using the steel cord 11 to be evaluated. When 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 obtained rubber composite 10 is peeled off, the end face 11A side of the steel cord 11 is exposed as shown in fig. 3. Therefore, the ratio of the area occupied by the rubber 12, which is obtained by subtracting the exposed regions of the first coating 1121 and the steel cord 11, for example, from the end surface 11A of the steel cord 11 can be calculated. The rubber 12 remaining on the end surface 11A of the steel cord 11 corresponds to a portion where at least the first coating 1121 is formed. Therefore, as described above, the ratio of the area occupied by the rubber 12 can calculate the ratio of the area of at least the end surface 11A of the steel cord 11 covered by the first coating 1121.

However, even at the portion where the first film 1121 is formed, a part of the rubber may be peeled off. Therefore, the area ratio of the first coating 1121 covering the end surface 11A in the longitudinal direction of the steel cord 11 is equal to or more than the area ratio calculated by the above-described method.

Further, the element distribution map of the end face 11A of the steel cord 11 may be performed to calculate the ratio of the area of the first coating 1121 covering the end face 11A of the steel cord 11.

Specifically, when element distribution mapping is performed on the end surface of the steel cord 11, the region of the component distribution of the first film 1121 is the region where the first film 1121 is formed. Therefore, from the result of the element distribution mapping, the ratio of the area of the first coating 1121 covering the end surface 11A of the steel cord 11 can be calculated by obtaining the ratio of the area of the region in which the first coating 1121 is formed in the end surface 11A of the steel cord 11.

The method for mapping the element distribution is not particularly limited, and SEM-EDX and the like can be used.

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

This is because the corrosion resistance of the end face can be particularly improved by setting the average thickness of the first coating 1121 to 5nm or more. This is because, when the rubber composite is produced, the first covering 131 can be formed to a sufficient thickness to improve the corrosion resistance of the end face.

By setting the average thickness of the first coating 1121 to 2 μm or less, the productivity at the time of manufacturing the steel cord can be improved. In addition, this is because, when the first coating 1121 is made too thick in the case of being applied to a rubber composite, the first covering 131 becomes porous, and there is a possibility that the effect of improving the corrosion resistance of the end face 11A is suppressed.

The method for determining the average thickness of the first coating 1121 is not particularly limited, and for example, the average thickness can be measured using a fluorescent X-ray film thickness meter. The measurement is performed at 3 points in total on the center of the end surface 11A of the steel cord 11 and 2 measurement points on a line segment passing through the center, and the average value thereof may be taken as the average thickness of the first coating 1121.

A line segment passing through the center of the end surface 11A of the steel cord 11 is a line segment having a diameter of a circle which is a contour line of the end surface 11A. Here, the diameter of a circle, which is the contour line of the end face 11A, is denoted by D. In this case, the two measurement points are two points located at 0.25D from the center on a line segment of a diameter of a circle which is an outline of the end surface 11A arbitrarily drawn on the end surface 11A so as to pass through the first film 1121.

While the embodiments have been described in detail, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the claims.

[ examples ]

The following examples are given by way of illustration, but the present invention is not limited to these examples.

(evaluation method)

First, a method for evaluating a rubber composite produced in the following experimental example will be described.

(1) Evaluation of Corrosion resistance of rubber composite

With respect to the rubber composites 10 produced in 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 at a ratio of the area occupied by the rubber 12 in the end face 11A in the longitudinal direction of the steel cord 11.

In the evaluation, in the image on the longitudinal end surface 11A side of the steel cord 11 from which the end surface side rubber 121 has been peeled off, a boundary line is visually drawn between the portion where the rubber 12 remains and the first coating 1121 and the portion where the longitudinal end surface 11A of the steel cord 11 is exposed. In addition, the contour line of the end face 11A is also drawn. The boundary line and the contour line of the end surface 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 is distinguished from the other portions by the binarization process, and the area of the portion where the rubber 12 remains is calculated.

Then, the ratio of the area occupied by the rubber 12 in one end face in the longitudinal direction of any one of the steel cords in the rubber composite is determined.

In the end face of the steel cord in the longitudinal direction, when the proportion of the area of the rubber 12 is 80% or more, it is evaluated as a, when it is 60% or more and less than 80%, it is evaluated as B, when it is 20% or more and less than 60%, it is evaluated as C, and when it is less than 20%, it is evaluated as D.

In each of the following experimental examples 1-1 to 1-10, 2 rubber composites were produced for evaluation. Then, the corrosion resistance was evaluated immediately after the production of one rubber composite (initial evaluation). The other rubber composite was subjected to a wet heat test and then evaluated for the corrosion resistance. The moist heat test is a test in which the rubber composite is left to stand in an environment at a temperature of 80 ℃ and a relative humidity of 95% for 150 hours (moist heat evaluation).

In both of the initial evaluation and the wet heat evaluation, A is the best, and the evaluation becomes worse in the order of B, C, and D.

When the rubber is peeled off, the rubber remaining on the end face of the steel cord corresponds to the portion where the cover is formed. Therefore, it can be said that the higher the wet heat evaluation performed after the wet heat test, the more the end face of the steel cord continues to be protected by the stable covering after the wet heat test, and the rubber composite in which the end face corrosion of the steel cord is suppressed.

However, as shown in table 1, the wet heat evaluation has a correlation with the initial evaluation, and when the initial evaluation is excellent, it can be said that the rubber composite suppresses the end surface corrosion of the steel cord. Therefore, only the initial evaluation was performed after experimental example 2.

In the initial evaluation, when the rubber is peeled off, the rubber portion remaining on the end face of the steel cord also corresponds to the portion where at least the first coating 1121 is formed. Therefore, the result of the initial evaluation may be a ratio of the area of at least the portion where the first coating 1121 is formed in the end surface of the steel cord in the longitudinal direction.

(2) Evaluation of Corrosion resistance of Steel cord

Evaluation was carried out using electrochemical measurements (LSV: linear sweep voltammetry). Specifically, the evaluation sample was immersed in an aqueous sulfuric acid solution having a pH of 1, and the current flowing at 0V (reference electrode: ag/AgCl, counter electrode: pt) was observed.

For the evaluation samples, 30 steel cords prepared under the same conditions were bundled to easily confirm the influence of the end portions, 10mm from the end face on which the first coating was formed was immersed in the sulfuric acid aqueous solution, and the current was measured.

In the measuring method, the corrosion current, which is the current value measured with respect to the steel cord before the plating film was formed on the end face prepared in the following Experimental example 1-1 (preparation of Steel cord) ", was 10mA/cm ² 。

Therefore, the measured current value was less than 10mA/cm ² When (2) was used, it was shown to have excellent corrosion resistance, and the current value was 10mA/cm ² In the above case, the corrosion resistance is poor.

(Experimental example)

The experimental conditions are explained below.

[ Experimental example 1]

A rubber composite and a steel cord were produced by the following procedure, and the corrosion resistance was evaluated. Experimental examples 1-1 to 1-9 are examples, and Experimental examples 1-10 are comparative examples.

(Experimental example 1-1)

(preparation of Steel cord)

A copper layer and a zinc layer were formed on the surface of the steel filament by plating. The copper layer used was copper pyrophosphateAs a plating solution, the current density was set to 22A/dm ² And film formation was performed with the treatment time set to 14 seconds. In addition, zinc sulfate was used as a plating solution for the zinc layer, and the current density was set to 20A/dm ² And the film formation was performed with the process time set to 7 seconds.

Then, the film was heated at 600 ℃ for 9 seconds in an atmospheric atmosphere to perform heat treatment, thereby diffusing the metal component and forming a plating film.

The obtained filament on which the plating film was formed was subjected to drawing processing so that the cord diameter became 1mm.

Next, the steel cord subjected to the drawing process is cut at a plurality of positions in the longitudinal direction so as to match the size of the rubber composite to be produced. The resulting steel cord has a second coating 1122 covering the side surface 11B side from the coating of the filament. As a result of analyzing the second coating 1122 by SEM-EDX, it was confirmed that Cu and Zn were contained.

A part of the obtained steel cord was used for the following production of a rubber composite, and the rest was used for the production of a 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 a natural rubber as a rubber component. The rubber composition contained 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 as an additive per 100 parts by mass of the rubber component.

(production of rubber composite)

The rubber composite 10 shown in fig. 1 and 2 is produced by using the steel cord and the rubber composition.

The steel cords 11 were arranged so that the longitudinal directions thereof were parallel to each other, and the side surfaces 11B of the steel cords 11 were covered with the rubber composition, thereby producing a rubber composite precursor. At this time, the longitudinal end face 11A of the steel cord 11 is not covered with the rubber composition but is exposed in advance.

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

Next, the end surfaces 11A in the longitudinal direction of the exposed steel cord 11 are pretreated.

The pretreatment is carried out by electrolytic degreasing with 20 mass% sulfuric acid, water washing, electrolytic degreasing with 10 mass% aqueous sodium hydroxide solution, water washing, immersion in 1 mass% sulfuric acid, and water washing in this order. Electrolytic degreasing using 20 mass% sulfuric acid was carried out at a liquid temperature of 45 ℃ and a current density was set to 10A/dm ² For 1 second. Electrolytic degreasing with 10 mass% sodium hydroxide was carried out at a liquid temperature of 40 ℃ with a current density of 10A/dm ² For 1 second. The immersion in 1 mass% sulfuric acid was performed at a liquid temperature of 35 ℃ for 1 second.

Then, a first coating 1121 is formed on the end surface 11A of the steel cord 11 in the longitudinal direction by a coating method. Specifically, a conductive copper nano ink (model No. GO-01) manufactured by shigai chemical corporation was applied to the entire end surface 11A in the longitudinal direction of the steel cord 11 and dried, thereby forming a first coating 1121 having a thickness of 0.15 μm.

The first coating 1121 is formed on the end surfaces 11A on both sides in the longitudinal direction of all the steel cords 11 included in the rubber composite under the same conditions. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.15 μm.

The average thickness of the first coating film 1121 was measured using a fluorescent X-ray film thickness meter. The thickness is measured at 3 points in total, the center of the end surface 11A of the steel cord 11 and 2 measurement points on a line segment passing through the center, and the average value thereof is defined as the average thickness of the first coating 1121.

A line segment passing through the center of the end face 11A of the steel cord 11 is a line segment having a diameter of a circle, which is the outline of the end face 11A. When the diameter of the circle that is the outline of the end surface 11A is D, the 2 measurement points are 2 points located at 0.25D from the center on a line segment that is arbitrarily drawn on the end surface 11A so as to pass through the first coating 1121 and that becomes the diameter of the circle that is the outline of the end surface 11A. The average thickness of the first coating 1121 was measured in the same manner in other experimental examples described below.

The conductive copper nano ink was coated and dried, and then a resin mask for protecting the rubber composition was peeled off. Then, a rubber composition is also disposed on the end face 11A side in the longitudinal direction of the steel cord 11, which is a precursor of the rubber composite.

Then, vulcanization was carried out at 180 ℃ for 10 minutes to obtain a rubber composite 10. The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first cover 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. A second cover 132 containing Cu, zn, and S is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively.

The first cover 131 containing Cu and S and the second cover 132 containing Cu, zn and S were confirmed by SEM EDX analysis. The analysis was carried out in the same manner as in experimental examples 1-2 to 1-10 below to identify the components contained therein. In other experimental examples described below, the second cover 132 includes Cu, zn, and S, and therefore, the description thereof is omitted. In each of the following experimental examples 1-2 to 1-9, 2, and 3, the first cover 131 and the second cover 132 contain at least Cu and S, and may be said to contain a copper-sulfur compound.

The obtained rubber composite 10 was used to evaluate the corrosion resistance of the rubber composite. The evaluation results are shown in table 1.

As shown in the evaluation results, when the end face side rubber 121 was peeled off to evaluate the corrosion resistance on the end face 11A side in the longitudinal direction of the steel cord 11, it was confirmed that the rubber 12 remained. Therefore, as described above, the end face 11A of the steel cord 11 can be said to be bonded to the rubber 12 via the first cover 131. Similarly, when the rubber is peeled off also from the side surface 11B side of the steel cord 11, it is confirmed that the rubber 12 remains on the side surface 11B of the steel cord 11. Therefore, it can be said that the side surfaces 11B of the steel cord 11 are bonded to the rubber 12 via the second cover 132.

For the following experimental examples 1-2 to 1-9, it was confirmed that the end surface 11A and the side surface 11B of the steel cord 11 were bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively, for the same reason.

(production of Steel cord)

As for the longitudinal end surface 11A of the steel cord obtained in the preparation of the steel cord of experimental example 1-1, the first coating 1121 was formed after the pretreatment, similarly to the case of producing the rubber composite in the present experimental example. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu was contained. The average thickness of the first film 1121 was 0.15 μm.

The corrosion resistance of the steel cord was evaluated on the obtained steel cord, and as a result, the current was less than 10mA/cm ² 。

(Experimental examples 1-2)

(production of rubber composite)

The rubber composite 10 was produced and evaluated in the same manner as in experimental example 1-1, except that the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 by the plating method under the following conditions.

In the present experimental example, the first coating 1121 was a laminated film in which a Cu layer and a Sn layer were laminated in this order on the end surface 11A, and the first coating 1121 was formed so that the total film thickness of the Cu layer and the Sn layer became 0.15 μm. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that it was 0.15 μm.

The Cu layer is formed using a Cu plating solution as a pyrophosphate bath. The Sn layer is formed using a Sn plating solution as a sulfuric acid bath. In forming each layer, the sponge electrode impregnated with the plating solution is brought into contact with the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed, and power is supplied from the end surface opposite to the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

After the first coating film 1121 is formed, washing with water, drying is performed, and then a resin mask for protecting the rubber composition is peeled off. Then, a rubber composition was disposed also on the longitudinal end face 11A side of the steel cord 11 that is a precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of experimental example 1-1, thereby obtaining a rubber composite 10.

The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first cover 131 containing Cu, sn, and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu and Sn were contained. The first coating film 1121 had an average thickness of 0.15 μm.

(Experimental examples 1 to 3)

(production of rubber composite)

In the present experimental example, the first film 1121 is a laminated film obtained by laminating a Cu layer, a Zn layer, and a Cu layer in this order on the end surface 11A, and the thickness of the Cu layer: thickness of Zn layer: thickness of Cu layer =3:4:3 and the total thickness is 0.15 μm, and the first film 1121 is formed. The average thickness of the first coating 1121 formed on the longitudinal end surfaces 11A of the steel cord 11 was measured and was confirmed to be 0.15 μm.

The Cu layer is formed using a Cu plating solution as a pyrophosphate bath. The Zn layer is formed using a Zn plating solution as a fluoboric acid bath. In forming each layer, the sponge electrode impregnated with the plating solution is brought into contact with the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed, and power is supplied from the end surface opposite to the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first covering 131 containing Cu, zn, and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

As for the longitudinal end surface 11A of the steel cord obtained in the preparation of the steel cord of experimental example 1-1, the first coating 1121 was formed after the pretreatment, similarly to the case of producing the rubber composite in the present experimental example. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu and Zn were contained. The first coating film 1121 had an average thickness of 0.15 μm.

(Experimental examples 1 to 4)

(production of rubber composite)

In the present experimental example, the first coating 1121 is a laminated film in which a Cu layer and a Zn layer are laminated in this order on the end surface 11A, and the thickness of the Cu layer: thickness of Zn layer =6:4, the first coating film 1121 was formed so that the total thickness became 0.15. Mu.m. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that it was 0.15 μm.

The Cu layer is formed using a Cu plating solution as a pyrophosphate bath. The Zn layer is formed using a Zn plating solution as a fluoroboric acid bath. In forming each layer, the sponge electrode impregnated with the plating solution is brought into contact with the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed, and power is supplied from the end surface opposite to the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first covering 131 containing Cu, zn, and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu and Zn were contained. The first coating film 1121 had an average thickness of 0.15 μm.

(Experimental examples 1 to 5)

(production of rubber composite)

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

The Cu layer as the first coating 1121 is formed using a Cu plating solution as a pyrophosphate bath. In forming the Cu layer, the sponge-attached electrode impregnated with the plating solution is brought into contact with the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed, and power is supplied from a surface opposite to the longitudinal end surface 11A of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first cover 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu was contained. The average thickness of the first film 1121 was 0.15 μm.

(Experimental examples 1 to 6)

(production of rubber composite)

The rubber composite 10 was produced and evaluated in the same manner as in experimental example 1-1, except that the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 by the displacement plating method under the following conditions.

In this experimental example, the first coating 1121 was a Cu layer, and the first coating 1121 was formed so that the film thickness became 0.15 μm. The average thickness of the first coating 1121 formed on the longitudinal end surfaces 11A of the steel cord 11 was measured and was confirmed to be 0.15 μm.

The first coating 1121 was formed by immersing the end faces of the steel cord 11 in the longitudinal direction to adjust the copper sulfate to 0.01 mol/dm ³ After 1 minute in a sulfuric acid bath, the mixture was washed with water and dried.

After the first coating film 1121 is formed, a resin mask that protects the rubber composition is peeled off. Then, a rubber composition was disposed also on the longitudinal end face 11A side of the steel cord 11 that is a precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of experimental example 1-1, thereby obtaining a rubber composite 10.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu was contained. The first coating film 1121 had an average thickness of 0.15 μm.

(Experimental examples 1 to 7)

(production of rubber composite)

In this experimental example, the first coating 1121 was a Cu — Zn alloy layer, and the first coating 1121 was formed so that the film thickness became 0.15 μm. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that it was 0.15 μm.

The Cu — Zn alloy layer as the first coating 1121 is formed using a plating solution in which zinc sulfate and L-histidine monohydrochloride monohydrate as an additive are added to a pyrophosphate bath for copper plating. The Cu-Zn alloy layer comprises Cu: zn =6:4, is formed. In forming the Cu — Zn alloy layer, the sponge-attached electrode immersed in the plating solution is brought into contact with the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed. Then, electricity is supplied from the surface opposite to the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

After the first coating film 1121 is formed, washing with water, drying is performed, and then a resin mask for protecting the rubber composition is peeled off. Then, a rubber composition was disposed also on the longitudinal end face 11A side of the steel cord 11 which is a precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of experimental example 1-1, thereby obtaining a rubber composite 10.

The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first cover 131 containing Cu, zn, and S is disposed on the end surface 11A in the longitudinal direction of the steel cord 11. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating film 1121 with SEM-EDX, it was confirmed that Cu and Zn were contained. The average thickness of the first film 1121 was 0.15 μm.

(Experimental examples 1 to 8)

(production of rubber composite)

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 became 0.15 μm. The average thickness of the first coating 1121 formed on the longitudinal end surfaces 11A of the steel cord 11 was measured and was confirmed to be 0.15 μm.

The Cu — Sn alloy layer as the first film 1121 is formed using a plating solution prepared by adding tin sulfate and L-histidine monohydrochloride monohydrate as an additive to a pyrophosphate bath for copper plating. The Cu-Sn alloy layer comprises the following components in molar ratio: sn =95:5, in the same manner. In forming the Cu — Sn alloy layer, the sponge-equipped electrode impregnated with the plating solution is brought into contact with the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed. Then, electricity is supplied from the surface opposite to the end surface 11A in the longitudinal direction of the steel cord 11 on which the first coating 1121 is to be formed. The thickness of the first coating 1121 is adjusted by the amount of power supplied.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first cover 131 containing Cu, sn, and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 1.

(production of Steel cord)

(Experimental examples 1 to 9)

(production of rubber composite)

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 became 0.15 μm. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that it was 0.15 μm.

The Cu — Sn alloy layer serving as the first coating 1121 is formed by immersing the longitudinal end surface of the steel cord 11 in a sulfuric acid bath containing copper and tin for 20 seconds, and then washing and drying the end surface. The Cu-Sn alloy layer is characterized in that the content ratio of Cu to Sn is Cu: sn =95:5, in the same manner.

After the first coating film 1121 is formed, a resin mask for protecting the rubber composition is peeled off. Then, a rubber composition was disposed also on the longitudinal end face 11A side of the steel cord 11 which is a precursor of the rubber composite, and vulcanization was performed under the same conditions as in the case of experimental example 1-1, thereby obtaining a rubber composite 10.

(production of Steel cord)

As in the case of producing the rubber composite in this experimental example, the end surface 11A in the longitudinal direction of the steel cord obtained in the preparation of the steel cord in experimental example 1-1 is subjected to the pretreatment, and then the first coating 1121 is formed. As a result of analyzing the first coating 1121 by SEM-EDX, it was confirmed that Cu and Sn were contained. The average thickness of the first film 1121 was 0.15 μm.

(Experimental examples 1 to 10)

(production of rubber composite)

In the production of the steel cord, the steel cord subjected to the drawing process is cut at a plurality of positions in the longitudinal direction so as to conform to the size of the rubber composite to be produced, and is used in a state where the first coating 1121 is not formed on the end face and the wire 111 is not exposed. In addition to the above points, a rubber composite was produced in the same manner as in the case of experimental example 1-1.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. The second coating 132 is disposed on the side surface 11B of the steel cord 11, but the first coating is not formed on the end surface 11A in the longitudinal direction of the steel cord 11. The evaluation results are shown in table 1.

(production of Steel cord)

The corrosion resistance of the steel cord obtained in the preparation of the steel cord of Experimental example 1-1 was evaluated, and as a result, the current was 10mA/cm ² 。

[ Table 1]

	Initial evaluation	Evaluation of moist Heat
			Experimental example 1-1	A	A
Experimental examples 1 to 2	A	B
			Examples 1 to 3	B	B
Experimental examples 1 to 4	C	C
			Examples 1 to 5	A	B
Experimental examples 1 to 6	C	C
			Examples 1 to 7	A	A
Experimental examples 1 to 8	B	B
			Experimental examples 1 to 9	A	A
Experimental examples 1 to 10	D	D

From the results shown in table 1, in each of experimental example 1-1 to experimental example 1-9, the initial evaluation and the wet heat evaluation were a to C, and it was confirmed that the initial evaluation and the wet heat evaluation were almost the same. In contrast, in examples 1 to 10, both of the initial evaluation and the damp-heat evaluation were D, and the second cover was not formed, and it was confirmed that the corrosion resistance was inferior to those of examples 1 to 9.

In addition, 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, and as a result, it was confirmed that the portion where the rubber remained was not discolored when the end face side rubber 121 was peeled off for the damp-heat evaluation. That is, it was confirmed that the portion where the first cover 131 is formed was protected from corrosion.

In contrast, in experimental examples 1 to 10, since almost no rubber remained on the end face 11A and the first coating 131 was not formed at the time of the damp-heat evaluation, it was confirmed that the entire end face 11A was discolored and corroded.

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

In addition, it was confirmed that the corrosion resistance of the steel cord could be improved by providing a coating film on the end surface in the longitudinal direction as shown in experimental examples 1-1 to 1-9 even when the steel cord was not formed into a rubber composite.

[ Experimental example 2]

A rubber composite was produced by the following procedure, and the corrosion resistance was evaluated. Experimental example 2-1 to Experimental example 2-5 are all examples.

(Experimental example 2-1)

When the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by a coating method, a conductive copper nano ink as a coating liquid similar to that in experimental example 1-1 was coated so that the thickness of the first coating 1121 after drying became 0.05 μm. The average thickness of the first coating 1121 formed on the end surface 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.05 μm.

In addition to the above points, a rubber composite was produced in the same manner as in the case of experimental example 1-1.

The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first cover 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 2.

Note that it was confirmed by SEM EDX that the first cover 131 contains Cu and S. The analysis was carried out in the same manner as in experimental examples 2-2 to 2-5 and experimental example 3 below to identify the components contained therein.

(Experimental example 2-2)

When the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by the coating method, the conductive copper nano ink as the same coating liquid as in experimental example 1-1 was coated so that the thickness of the first coating 1121 obtained after drying became 0.1 μm. The average thickness of the first coating 1121 formed on the end surface 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.1 μm.

Except for the above points, a rubber composite was produced in the same manner as in the case of experimental example 1-1.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first cover 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 2.

(Experimental examples 2 to 3)

When the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by a coating method, the conductive copper nano ink, which is the same coating liquid as in experimental example 1-1, was coated so that the thickness of the first coating 1121 obtained after drying became 0.5 μm. The average thickness of the first coating 1121 formed on the end surface 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.5 μm.

(Experimental examples 2 to 4)

When the first coating 1121 was formed on the entire end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by a coating method, a conductive copper nano ink as the same coating liquid as in experimental example 1-1 was coated so that the thickness of the first coating 1121 obtained after drying became 1 μm. The average thickness of the first coating 1121 formed on the end surface 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 1 μm.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first covering 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 2.

(Experimental examples 2 to 5)

When the first coating 1121 was formed on the entire end face 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by the coating method, the conductive copper nano ink as the same coating liquid as in experimental example 1-1 was coated so that the thickness of the first coating 1121 obtained after drying became 2 μm. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 2 μm.

[ Table 2]

	Evaluation results
		Experimental example 2-1	C
Experimental examples 2-2	A
		Experimental examples 2 to 3	A
Experimental examples 2 to 4	B
		Experimental examples 2 to 5	C

From the results shown in table 2, it was confirmed that the corrosion resistance tended to be improved by increasing the thickness of the first coating film. This is considered to be because a sufficient thickness of the coating can be formed by making the first coating film a certain thickness or more.

As shown in experimental examples 2 to 4 and 2 to 5, it was confirmed that the corrosion resistance tended to decrease when the thickness of the first coating film increased beyond a certain thickness. This is considered to be because the reaction layer with S (sulfur) in the rubber is formed to be porous.

[ Experimental example 3]

A rubber composite was produced by the following procedure, and the corrosion resistance was evaluated. Experimental example 3-1 to Experimental example 3-3 are all examples.

(Experimental example 3-1)

When the first coating 1121 was formed on the end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by a coating method, a conductive copper nano ink as a coating solution similar to that in experimental example 1-1 was coated so that the thickness of the first coating 1121 obtained after drying became 0.15 μm.

When the coating liquid is applied to the longitudinal end surface 11A of the steel cord 11, a portion of the longitudinal end surface 11A of the steel cord 11 is masked in advance so that the ratio of the area of the end surface in the region where the coating liquid is applied is 20%. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.15 μm.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first cover 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 3.

(Experimental example 3-2)

When the first coating 1121 was formed on the end surface 11A in the longitudinal direction of the steel cord 11 contained in the precursor of the rubber composite by the coating method, the conductive copper nano ink as the same coating liquid as in experimental example 1-1 was coated so that the thickness of the first coating 1121 obtained after drying became 0.15 μm.

When the coating liquid is applied to the longitudinal end surface 11A of the steel cord 11, a part of the longitudinal end surface 11A of the steel cord 11 is masked in advance so that the ratio of the area of the end surface in the region where the coating liquid is applied is 60%. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.15 μm.

The rubber 12 is disposed in the resulting rubber composite 10 so as to cover the entire surface of the steel cord 11. A first covering 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 3.

(Experimental example 3-3)

When the coating liquid is applied to the longitudinal end surfaces 11A of the steel cord 11, a part of the longitudinal end surfaces 11A of the steel cord 11 is masked in advance so that the ratio of the area of the end surfaces to which the coating liquid is applied is 80%. The average thickness of the first coating 1121 formed on the end surfaces 11A of the steel cord 11 in the longitudinal direction was measured, and it was confirmed that the thickness was 0.15 μm.

The rubber 12 is disposed on the entire surface of the steel cord 11 of the resulting rubber composite 10. A first covering 131 including Cu and S is disposed on an end surface 11A of the steel cord 11 in the longitudinal direction. The second cover 132 is disposed on the side surface 11B of the steel cord 11. The end surface 11A and the side surface 11B of the steel cord 11 are bonded to the rubber 12 via the first cover 131 and the second cover 132, respectively. The evaluation results are shown in table 3.

[ Table 3]

	Evaluation results
		Experimental example 3-1	C
Experimental example 3-2	B
		Experimental examples 3 to 3	A

From the results shown in table 3, it was confirmed that the higher the ratio of the area of the region coated with the coating liquid in the end surface in the longitudinal direction of the steel cord, the higher the results of the corrosion resistance test. In the longitudinal end face of the steel cord, the ratio of the area coated with the coating liquid is increased, whereby the ratio of the area of the end face to be coated with the coating film is increased, and the ratio of the area covered with the coating is also increased in the longitudinal end face of the steel cord. As a result, it is considered that the corrosion resistance can be improved.

Description of the symbols

10. Rubber composite

11. Steel cord

11A end face

11B side surface

111. Wire rod

112. Film coating

1121. A first coating film

1122. Second coating film

12. Rubber composition

121. End face rubber

13. Covering article

131. First cover

132. Second cover

X-axis direction (Width direction)

Y Y-axis direction (length direction)

Z-axis direction (thickness direction)

40. Tyre for vehicle wheels

41. Tread portion

42. Sidewall part

43. Bead part

44. Inner lining

45. Carcass (rubber complex)

46. Belt layer (rubber complex)

47. A bead wire.

Claims

1. A rubber composite, wherein the rubber composite has:

a steel cord, and

a rubber covering at least a part of the surface of the steel cord, wherein

A first cover containing Cu is disposed on an end face of the steel cord in the longitudinal direction.

2. The rubber composite of claim 1, wherein the first cover further comprises S.

3. The rubber composite of claim 1 or claim 2, wherein the first cover further comprises Zn.

4. The rubber composite of claim 3, wherein the first cover further comprises one or more selected from Sn, cr, fe, co, and Ni.

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

6. The rubber composite according to any one of claim 1 to claim 5, wherein the end face of the steel cord is bonded to the rubber via the first cover.

7. The rubber composite of any one of claim 1 to claim 6, wherein the first cover covers more than 20% of the end face.

8. A rubber composite according to any one of claim 1 to claim 7, wherein a secondary covering containing Cu is provided on a side of the steel cord.

9. A tire, wherein the tire comprises the rubber composite of any one of claim 1 to claim 8.

10. A steel cord having a coating film containing Cu disposed on the longitudinal end surface thereof.

11. A steel cord according to claim 10, wherein said coating film further contains Zn.

12. A steel cord according to claim 11, wherein said coating film further contains one or more selected from the group consisting of Sn, cr, fe, co and Ni.

13. A steel cord according to any one of claim 10 to claim 12, wherein said coating covers 20% or more of said end face.