JP2006283270A - Brass plated copper wire for reinforcement of rubber article and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brass plated copper wire and a method for producing the same, securely improving adhesion of the brass plated copper wire with rubber. <P>SOLUTION: The brass plated copper wire 10 for reinforcement of rubber article comprises a plated layer 11 on the surface, wherein the plated layer 11 comprises an amorphous part 11a composed of crystalline particles with ≤20 nm of particle diameter. The plated layer 11 has a laminated structure 13 comprising the amorphous part 11a on the surface side and the crystalline part 11b inside, wherein the amorphous part 11a comprises crystal particles with ≤20 nm of particle diameter, and the crystalline part 11b comprises crystal particles with ≥20 nm of particle diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brass-plated steel wire for reinforcing rubber articles having a surface provided with a brass (brass) plating layer, which is used for a wire of a tire-reinforcing steel cord. It is related with the improvement of adhesiveness.

Conventionally, as a steel wire for reinforcing a rubber article used for a wire of a steel cord for reinforcing a tire, a brass-plated steel wire having a surface provided with a brass plating layer is used. This brass-plated steel wire is manufactured by cold-drawing a steel wire subjected to a heat treatment such as patenting and a brass plating process to a predetermined wire diameter.
Regarding the adhesion between the brass-plated steel wire and the rubber, for example, in the vulcanization process at the time of tire production, the sulfur in the rubber reacts with the copper in the brass plating by being heated in contact with the rubber. Thus, it is known that an adhesive layer is formed. The adhesive layer is required to be formed quickly and reliably in the vulcanization process (initial adhesion performance) and not deteriorated by moisture or heat when the rubber article is used (adhesion durability performance).

As a method for improving the adhesion of a brass-plated steel wire for reinforcing rubber articles with a rubber, conventionally, an alloying element such as Fe or Ni is added to the plating component, and the surface layer is alloyed (for example, Patent Documents 1 and 2), a method of performing plasma treatment on a steel wire subjected to brass plating (for example, Patent Document 3), and a method for limiting the oxygen ratio on the outermost surface of the plating layer (for example, Patent Document 4) or a method of performing blasting after wire drawing (for example, see Patent Document 5) is known.
JP-A-8-209386 JP 2002-13081 A JP 2003-160895 A JP 2004-68102 A JP-A-5-278147

  However, none of the above conventional methods can satisfy both the initial adhesive performance and the adhesive durability performance, although some improvement in adhesiveness is observed.

  The present invention has been made in view of the above-mentioned conventional problems, and provides a brass-plated steel wire for reinforcing rubber articles and a method for producing the same, which can reliably improve the adhesion between the brass-plated steel wire and rubber. The purpose is to do.

The brass-plated steel wire for reinforcing rubber articles according to the present invention is a brass-plated steel wire for reinforcing rubber articles having a brass plating layer on the surface, and the brass plating layer is formed of crystal grains having a particle size of 20 nm or less. It has a non-crystalline part.
A brass-plated steel wire for reinforcing rubber articles having a brass plating layer on the surface, the brass plating layer comprising a laminated structure part in which a noncrystalline part on the surface side and a crystalline part on the inside are laminated The amorphous part is formed by crystal grains having a particle size of 20 nm or less, and the crystalline part is formed by crystal grains having a particle diameter exceeding 20 nm.
The volume ratio of the laminated structure portion to the whole brass plating layer is also 50% or more.
The ratio of the area occupied by the surface of the amorphous portion to the entire surface of the brass plating layer is 80% or more.
The area ratio of the surface of the amorphous portion of the laminated structure portion to the entire surface of the brass plating layer is 20% or more, and the volume ratio of the amorphous portion of the laminated structure portion to the entire laminated structure portion is It is also characterized by being 20% or more and 80% or less.
The method of manufacturing a brass-plated steel wire for reinforcing rubber articles according to the present invention comprises forming a crystalline brass plating layer on the surface of the steel wire and then forming an amorphous brass plating layer on the surface of the crystalline brass plating layer. A brass plating layer having a laminated structure composed of a lower crystalline portion and a non-crystalline portion of the surface layer is formed on the surface of the steel wire.
After forming a crystalline brass plating layer on the surface of the steel wire, by strongly processing only the extreme surface layer of this crystalline brass plating layer, the lower crystalline portion and the surface layer are formed on the surface of the steel wire. The present invention is also characterized in that a brass plating layer having a laminated structure composed of non-crystalline parts is formed.

In the brass-plated steel wire of the present invention, the surface brass-plated layer had an amorphous part formed by crystal grains having a grain size of 20 nm or less. For example, an amorphous brass plating layer is formed on the surface of a steel wire subjected to crystalline brass plating, or only the extreme surface of a steel wire subjected to crystalline brass plating is strongly processed. According to the brass-plated steel wire of the present invention in which the amorphous part is formed in the brass-plated layer, a brass-plated steel wire with good initial adhesion performance with rubber can be obtained.
According to the brass-plated steel wire provided with the laminated structure portion in which the amorphous portion on the surface side and the crystalline portion on the inner side are laminated, a brass-plated steel wire having good adhesion durability can be obtained.
According to the brass-plated steel wire in which the volume ratio of the laminated structure portion to the entire brass-plated layer is 50% or more, it is possible to obtain a brass-plated steel wire having both good initial adhesion performance and adhesion durability performance. it can.
According to the brass-plated steel wire in which the area ratio of the surface of the amorphous portion to the entire surface of the brass-plated layer is 80% or more, a brass-plated steel wire with better initial adhesion performance can be obtained. .
The area ratio of the surface of the non-crystalline portion of the laminated structure portion to the entire surface of the brass plating layer is 20% or more, and the volume ratio of the non-crystalline portion of the laminated structure portion to the entire laminated structure portion is 20%. According to the brass-plated steel wire set to be not less than 80% and not more than 80%, a brass-plated steel wire having good initial adhesion performance and adhesion durability performance can be obtained.
According to the method for producing a brass-plated steel wire for reinforcing rubber articles according to the present invention, as described above, a brass-plated steel wire having excellent adhesion performance with rubber can be produced.

Best form 1
Hereinafter, the best mode 1 of the present invention will be described with reference to FIGS.
A brass-plated steel wire 10 will be described with reference to FIG. The brass-plated steel wire 10 has a steel wire 12 and a brass-plated layer 11 formed on the surface of the steel wire 12. The brass plating layer 11 includes a laminated structure portion 13 in which a noncrystalline portion 11a on the front side and a crystalline portion 11b on the inner side are laminated. The amorphous part 11a is formed of crystal grains having a particle diameter of 20 nm or less. In other words, the amorphous portion 11a is a substantially amorphous portion that is formed of fine crystal grains of 20 nm or less, or has a feature that the crystal grains cannot be distinguished. The crystalline part 11b is a part formed by crystal grains having a grain size exceeding 20 nm. For example, when the backscattered electron beam pattern is taken, a clear Kikuchi pattern corresponding to the crystal orientation of Cu is obtained in the crystalline part 11b, but the amorphous part 11a does not have a clear crystal structure. The Kikuchi pattern cannot be obtained.

  In the best mode 1, the area ratio (hereinafter referred to as area ratio A) occupied by the surface of the amorphous portion 11a of the multilayer structure portion 13 with respect to the entire surface of the brass plating layer 11 is set to 80% or more. The volume ratio (hereinafter referred to as volume ratio A) of the structural portion 13 with respect to the entire brass plating layer 11 was set to 50% or more.

The brass-plated steel wire 10 according to the best mode 1 includes the brass plating layer 11 having the laminated structure portion 13 in which the amorphous portion 11a on the surface side and the crystalline portion 11b on the inner side are laminated. Therefore, the following effects could be obtained.
The amorphous portion 11a of the brass plating layer 11 has a very high lattice defect concentration and thus has a high activity and a high diffusion rate of Cu atoms. For this reason, the amorphous portion 11a of the brass-plated steel wire 10 and the rubber were brought into contact with each other in the vulcanization process when the tire was manufactured using the brass-plated steel wire 10 as an element wire of the tire reinforcing steel cord. When the brass-plated steel wire 10 is heated in the state, the adhesion reaction between the brass-plated steel wire 10 and rubber proceeds rapidly. Therefore, since the adhesive layer between the brass-plated steel wire 10 and the rubber is quickly formed in the vulcanization process, the initial adhesion performance is improved (hereinafter referred to as effect (1)). That is, in the best mode 1, it was possible to obtain a brass-plated steel wire 10 with good initial adhesion performance.
Further, even if the tire is placed in an environment (for example, a high temperature and high humidity environment) where Cu atoms are rapidly consumed at the adhesion interface after the adhesive layer is formed, Cu atoms from the amorphous portion 11a. Is promptly supplied, so that Cu atoms in the adhesive layer are prevented from being diluted and a strong adhesive layer is maintained.
Further, the crystalline part 11b of the brass plating layer 11 has a lower activity and a slower diffusion rate of Cu atoms than the non-crystalline part 11a. Therefore, when the brass plating layer 11 has only a highly active non-crystalline part 11a, the brass plating / steel interface is likely to become brittle in a poor wet heat degradation environment, and is likely to be a starting point of destruction. Therefore, in the best mode 1, by providing the crystalline portion 11b in the brass plating layer 11, the adhesion durability performance can be improved. That is, since the brass plating layer 11 has the crystalline part 11b that gradually promotes the adhesion reaction with the rubber, the copper does not move even when the reaction due to moisture or heat during the use of a rubber article such as a tire proceeds. It was possible to ensure adhesion durability without being depleted early (hereinafter referred to as effect (2)).

  Therefore, according to the brass-plated steel wire 10 according to the best mode 1, it was possible to obtain the brass-plated steel wire 10 having both good initial adhesiveness and adhesion durability.

For example, the brass-plated steel wire 10 of the best mode 1 is formed by strongly processing only the extreme surface of the brass-plated layer of the steel wire 12 subjected to crystalline brass plating, and the surface of the brass-plated layer is made amorphous. It can be manufactured by altering the part 11a.
The strong processing of the extreme surface of the brass plating layer is performed, for example, by wire drawing using a die.
When lubrication is insufficient in the wire drawing process, it is known that when the work wire and the tool come into contact directly or through an incomplete film, a strong work layer is formed on the surface of the work wire. This strongly processed layer is a portion into which extremely high density lattice defects are introduced. The generation of such a hard-worked layer is generally said to cause problems such as brass plating dropout, steel wire material deterioration, or wire breakage or die wear. By processing, an extremely thin strong processing layer can be formed on the extreme surface of the brass plating layer.
For example, in order to perform wire drawing in a state where the lubricity is lowered to some extent by wet drawing using a liquid lubricating liquid, the concentration of the lubricating component in the lubricating liquid is higher than the concentration used for normal drawing. Lower the wire for drawing or lower the temperature of the lubricant below the recommended temperature for the lubricant.
Depending on the strength and wire diameter of the steel wire to be manufactured, how much the lubricity is reduced depends on the strength and wire diameter of the steel wire to be manufactured. The concentration may be 80% to 20% of the concentration of the lubricating liquid. If the lubricity is lowered too much, the brass plating may fall off, the steel wire material may deteriorate, or the wire may break or die wear. On the other hand, if the method of lowering the lubricity is insufficient, the ratio of the non-crystalline part 11a on the surface of the brass plating layer is reduced, so that the adhesiveness is deteriorated.

Also, if the heat generation during wire drawing is too large, there is a possibility that the lattice defect density of brass plating will decrease due to temperature rise and the ductility of steel wire may be deteriorated. It is preferable to set it to 150 ° C. or lower when the wire drawing conditions are set and the temperature of the outgoing wire from the die is measured with a contact thermometer.
・ Drawing conditions
-1 Set the area reduction per die low.
-Set the wire drawing speed lower.
-Cooling the die to suppress the temperature rise.
-Cool the wire that enters and / or exits the die.
At this time, in order to form the laminated structure portion of the amorphous portion and the crystalline portion, it is better to increase the thickness of the brass plating layer.
In addition, when manufacturing by wet continuous wire drawing, wire drawing in a finishing die or several dies downstream of the wire drawing including the finishing die is performed in a state where the lubricity as described above is reduced to some extent, If the dies are used under good lubrication conditions, a brass plating layer having a crystalline inside and an amorphous surface can be reliably produced.

  As described above, according to the best mode 1, by drawing a brass-plated steel wire with the lubricity lowered to some extent, the surface of the steel wire 12 has an amorphous portion 11a and a crystalline portion 11b. Since the brass-plated steel wire 10 having the laminated structure portion 13 having a structure in which the area ratio A is 80% or more and the volume ratio A is 50% or more is formed, good initial adhesion is achieved. A brass-plated steel wire 10 having both performance and adhesion durability performance could be obtained.

  In the best mode 1, a steel wire having a crystalline brass plating layer formed on its surface is drawn in a state where the lubricity is lowered to some extent, and the inside is crystalline and the surface is amorphous. Although the layer 11 is formed, after forming a crystalline brass plating layer on the surface of the steel wire, an amorphous brass plating layer is formed on the surface of the crystalline brass plating layer by, for example, plasma CVD The brass plating layer may be a brass plating layer having a laminated structure including a lower layer portion made of a crystalline material and a surface layer portion made of an amorphous material. In this case, it is possible to make the outermost surface almost amorphous while maintaining the crystallinity inside the brass plating layer well.

Example of Best Mode 1 A brass-plated steel wire (Example 1) drawn with the lubricity lowered to some extent and a brass-plated steel wire (Comparative Example 1) drawn under a conventional good lubricating condition Each was produced. 2 (a) and 2 (b) are diagrams showing cross sections of the brass-plated steel wire of Example 1 and Comparative Example 1, and the brass-plated steel wire of Example 1 has an area ratio A of 96%. On the other hand, in the brass-plated steel wire of the comparative example, the area ratio A was 56%. The area ratio A was calculated from the degree to which a clear Kikuchi pattern corresponding to the crystal orientation of Cu was obtained by taking a backscattered electron pattern on the surface of the produced brass-plated steel wire. The brass-plated steel wires used in the test all had a wire diameter of 0.300 mm, a tensile strength of 3200 MPa, and a brass plating adhesion amount of 3.5 g per kg.
As a result of examining the adhesiveness with rubber for these steel wires, it was confirmed that the brass-plated steel wires of the examples were superior in initial adhesion performance and adhesion durability compared to the brass-plated steel wires of the comparative examples. confirmed.

Best form 2
When the area ratio A is 20% or more and the volume ratio (hereinafter referred to as volume ratio B) of the non-crystalline part of the laminated structure portion to the entire laminated structure part is 20% or more and 80% or less, rubber As a result, a brass-plated steel wire 10 having excellent initial adhesion performance, adhesion layer maintenance performance, and adhesion durability performance was obtained. When the area ratio A was less than 20%, the effects described in the above effects (1) and (2), that is, excellent initial adhesion performance and adhesion durability performance were not obtained. In addition, when the volume ratio B was less than 20%, the effect described in the above effect (1), that is, excellent initial adhesion performance was not obtained. When the volume ratio B was less than 20%, the effects described in the above effects (1) and (2), that is, excellent initial adhesion performance and adhesion durability performance were not obtained. Furthermore, when the volume ratio B exceeded 80%, the effect described in the above effect (2), that is, excellent adhesion durability performance was not obtained. Further, when the volume ratio B was 25% or more and 75% or less, further excellent initial adhesion performance and durable adhesion performance were obtained. When the area ratio A was 80% or more, the initial adhesion performance was further improved.

Example of Best Mode 2 Brass-plated steel wires having different area ratios A and volume ratios B were produced, and the adhesion performance was evaluated. The area ratio A was calculated from the degree to which a back-scattered electron pattern was taken for the surface of the produced brass-plated steel wire and a clear Kikuchi pattern corresponding to the crystal orientation of Cu was obtained. The volume ratio B was calculated by image analysis of a cross-sectional observation image of the produced brass-plated steel wire. FIG. 3 shows cross sections of a brass-plated steel wire (Examples 2 and 3) drawn with the lubricity lowered to some extent and a brass-plated steel wire (Comparative Example 2) drawn under conventional good lubrication conditions. FIG. 4 shows the area ratio A and the volume ratio B calculated by the above method. As for the adhesive performance evaluation, the initial adhesion was made by twisting brass-plated steel wires with a wire diameter of 0.30 mm into a 1 × 3 structure to produce steel cords, arranging them in parallel at equal intervals, and coating them with rubber from both sides. Then, after vulcanization at 160 ° C. for 7 to 15 minutes, the steel cord was peeled from the rubber for the obtained rubber-steel cord composite, and the rubber adhesion rate at that time was measured. The index is 100. It shows that adhesiveness is so favorable that a numerical value is large. In addition, the adhesive durability was the same as the initial adhesiveness, and after coating with rubber and vulcanizing at 160 ° C. for 20 minutes, the resulting rubber-steel cord composite had an atmospheric pressure of 95% humidity and 75% temperature. The steel cord was left to stand for 7 to 14 days in the atmosphere, and then the steel cord was peeled off. The rubber adhesion rate at that time was measured, and the result was shown as an index with Comparative Example 2 taken as 100. It shows that adhesiveness is so favorable that a numerical value is large. The respective results are shown in FIG. The brass-plated steel wire of Example 2 in which the area ratio A was 98% and the volume ratio B was 45% was the condition described in the best mode 2, that is, the area ratio A was 80% or more and the volume ratio B was 25%. The condition of 75% or less is satisfied, and both the initial adhesion performance and the adhesion durability performance are superior to those of Comparative Example 2. In the brass-plated steel wire of Example 3 that did not satisfy the condition that the volume ratio B was 80% or less, the adhesion durability performance was worse than that of Comparative Example 2, and the above-described effect (2) was not sufficiently obtained.

  Regardless of whether or not the laminated structure portion 13 is provided, the initial adhesion performance to rubber becomes better as the area ratio A is larger, so the area ratio A may be 100%.

It is a schematic diagram which shows the cross section of a brass plating steel wire. It is the figure which compared the cross section of the brass plating steel wire of Example 1 and Comparative Example 1. FIG. It is the figure which compared the cross section of the brass plating steel wire of Example 2, 3 and the comparative example 2. FIG. It is a figure which shows the result of the adhesive performance evaluation of Examples 2 and 3 and Comparative Example 2.

Explanation of symbols

10 brass-plated steel wire, 11 brass-plated layer, 11a amorphous part,
11b Crystalline part, 12 steel wire, 13 laminated structure part.

Claims (7)

  A brass-plated steel wire for reinforcing rubber articles having a brass plating layer on the surface, wherein the brass plating layer has an amorphous portion formed by crystal grains having a particle size of 20 nm or less. Brass plated steel wire for rubber article reinforcement.   A brass-plated steel wire for reinforcing rubber articles having a brass plating layer on the surface, the brass plating layer comprising a laminated structure part in which a noncrystalline part on the surface side and a crystalline part on the inside are laminated A brass-plated steel wire for reinforcing rubber articles, characterized in that the amorphous part is formed by crystal grains having a particle size of 20 nm or less, and the crystalline part is formed by crystal grains having a particle diameter exceeding 20 nm. .   The brass-plated steel wire for reinforcing rubber articles according to claim 2, wherein the volume ratio of the laminated structure portion to the entire brass-plated layer is 50% or more.   The brass for reinforcing rubber articles according to any one of claims 1 to 3, wherein an area ratio of the surface of the amorphous portion to the entire surface of the brass plating layer is 80% or more. Plated steel wire.   The area ratio of the surface of the amorphous portion of the laminated structure portion to the entire surface of the brass plating layer is 20% or more, and the volume ratio of the amorphous portion of the laminated structure portion to the entire laminated structure portion is It is 20% or more and 80% or less, The brass plating steel wire for rubber article reinforcement of Claim 2 characterized by the above-mentioned.   A method for producing a brass-plated steel wire for reinforcing rubber articles according to any one of claims 1 to 5, wherein a crystalline brass-plated layer is formed on the surface of the steel wire, and then the crystalline By forming an amorphous brass plating layer on the surface of the brass plating layer, a brass plating layer having a laminated structure comprising a lower crystalline portion and a noncrystalline portion on the surface of the steel wire. A method of manufacturing a brass-plated steel wire for reinforcing rubber articles, characterized in that   A method for producing a brass-plated steel wire for reinforcing rubber articles according to any one of claims 1 to 5, wherein a crystalline brass-plated layer is formed on the surface of the steel wire, and then the crystalline The brass plating layer having a laminated structure consisting of the lower crystalline part and the amorphous part of the surface layer is formed on the surface of the steel wire by strongly processing only the extreme surface layer of the brass plating layer. A method for producing a brass-plated steel wire for reinforcing rubber articles.

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