JPH08209388A - Brass plated steel wire having good adhesiveness to rubber - Google Patents

Abstract

PURPOSE: To produce a brass plated steel wire having an excellent adhesiveness to rubber by regulating the content of Fe in the extreme surface layer of plating in particular, with respect to a technique for improving the adhesiveness of the steel wire for reinforcing the rubber to the rubber. CONSTITUTION: This extremely fine wire to be used by executing drawing after subjecting the steel wire to brass plating mainly composed of Cu and Zn contains Fe in the brass plating layer and the concn. ratio of the Fe in the extreme surface layer of the brass plating interns of Fe/(Cu+Zn+Fe) is 2 to 50%. The brass plated steel wire described above has the good adhesiveness to the rubber. The extreme surface layer of the brass plating described above is 0.01 to 0.03μm from the plating surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the adhesion of a rubber reinforcing steel wire to rubber, and particularly to a brass having excellent adhesion to rubber by regulating the Fe content in the outermost layer of the plating. Regarding plated steel wire.

[0002]

2. Description of the Related Art In general, a technique of compounding plated steel wire with rubber for reinforcement is widely used industrially such as automobile tires, high-pressure rubber hoses, and conveyor belts. In particular, automobile tire cords are highly required to have adhesiveness with rubber, and further improvements have been recently made. To improve this adhesion, in the vulcanization process in the step of embedding the brass-plated steel wire in the rubber, combine S in the rubber and Cu, which is the plating component, and strengthen the adhesion at the interface. It is important how many Cu _X S compounds that have the function of producing are present and present.

Regarding the mechanism of adhesion between the rubber and the metal, how to strengthen the reaction layer at the adhesion interface and how to prevent direct contact with the metal surface have been studied as a study on the rubber. We have only concluded that further studies should be conducted in terms of both reaction and rubber physical properties. But,
As a general theory among them, when an activity promoter is added to rubber, S reacts with the rubber quickly, free S in the rubber decreases, and the reaction from CuS to Cu ₂ S ends, and It has been reported that in the paper, oxidation occurs at the interface and the adhesion is rather lowered. From this, CuS to Cu
It is understood that sustaining the reaction to ₂ S during vulcanization is important for adhesion. (See, for example, Journal of Japan Rubber Association, Vol. 45 (1972) No. 10, P920-931)

In addition, as a known technique for defining the brass outermost surface element in order to improve the adhesion between the ultrafine steel wire and the rubber, for example, in JP-A-54-4250, the outermost surface layer having a thickness of 10 angstroms is disclosed. Cu concentration of about 20
.About.50% by weight. In Japanese Examined Patent Publication No. 5-21990, Cu on the outermost surface of Cu, Zn and Ni ternary brass plating is less than 4% by weight, gradually increases from the outermost surface to a depth of 50 angstroms, and is deeper than that.
˜14% by weight. JP-A-57-
Japanese Unexamined Patent Publication No. 56110 discloses a technique in which a ternary brass plating of Cu, Zn, and Co has a Co concentration gradient in the outermost surface layer of about 500 angstroms.

In the above-mentioned prior art, the Cu concentration in the outermost layer of brass plating, which is important for the adhesiveness to rubber, is specified, and Ni, C
The addition of o and the concentration thereof are specified. Although the regulation of the Cu concentration, which contributes most to the adhesion with rubber, is effective, it is not easy to adjust the Cu concentration because the Cu and Zn do not always have a clean concentration gradient in the depth direction when wire drawing is performed. . In addition, the plated material containing Ni and Co is disadvantageous in cost.

Also, in the actual manufacturing process, the adhesion condition is the residual condition of the plating after wire drawing and the characteristics of the plating itself,
And is greatly affected by other process factors. Therefore, in order to obtain stable and good adhesion, manufacturing process control and plating control require considerable labor and cost.

More recently, even in plating technology,
Diffusion plating is the mainstream due to pollution problems, and there is a concentration gradient of Cu and Zn components in brass plating due to mutual diffusion caused by this diffusion heat treatment. Therefore, the alloy concentration is adjusted by diffusion plating and bonded. In order to optimize the sex, the process control becomes more complicated and enormously difficult. For this reason, there is a demand for technological development that enables simplification of manufacturing process control for obtaining stable and good adhesiveness.

[0008]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to investigate the addition of elements other than brass components as components during plating, and the regulation of the surface layer portion concentration of the components to determine the Cu generated at the interface. By promoting the formation of ₂ S (rather Cu _1.96 S) compounds, maintaining this reaction continuously during the vulcanization process, and stably forming Cu ₂ S (rather Cu _1.96 S) compounds, Provide a brass-plated steel wire with excellent adhesion. Another object of the present invention is to optimize the diffusion plating process of the plating process, and further expand the tolerance of the process conditions such as wire drawing, thereby improving the adhesiveness with rubber in which the variation in the adhesive properties is reduced. To provide excellent brass-plated steel wire.

[0009]

Means for Solving the Problems The present invention achieves the above-mentioned objects, and the gist thereof is as follows: (1) Wire-drawing is performed after brass plating mainly containing Cu and Zn on a steel wire. In the ultrafine steel wire to be used and used, the brass plating layer contains Fe, and the Fe concentration ratio of the brass plating outermost layer portion is Fe / (Cu + Zn + Fe) = 2 to 50%. Brass-plated steel wire having good adhesiveness, (2) Brass-plated steel wire having good adhesiveness to rubber according to (1), wherein the brass-plated outermost layer is 0.01 to 0.03 μm from the plated surface. Is.

[0010]

The present inventors have made a detailed study of the wire drawing strain, surface element concentration, and adhesiveness with rubber of brass-plated steel wire. As a result, it was found that the concentration of Fe appearing in the plating from the steel substrate during wire drawing was most easily controlled, and the relationship with the adhesiveness with rubber was obtained. FIG. 1 shows the relationship between the Fe concentration ratio of the brass plating layer and the initial rubber adhesiveness. For this analysis, an Auger spectrophotometer was used to sputter from the brass surface and to detect F at a position of about 0.02 μm.
e concentration ratio. A typical example of the Auger spectroscopic analysis result is shown in FIG. In this figure, the horizontal axis is the depth from the plating surface, and indicates the relative intensity of each component at each position. For example, Cu, Zn and F at 0.02 μm position
The concentration ratio of e is shown on the dotted line in the figure.

Further, the surface Fe concentration is approximately determined by the brass plating thickness and the wire drawing strain, and Cu and Zn at that time are determined.
Even if the concentration is not specified in detail, if the Cu / Zn ratio at the time of plating is about 60/40 to 70/30 which is general, there is almost no effect. Further, the portion that contributes to the adhesion with the rubber has a thickness of 0.01 to 0.03 μm, which is the outermost surface layer of the plating.
The concentration ratio of Fe / (Cu + Zn + Fe) = 2 to 50% is the range in which the adhesiveness with rubber is the best. This is because the presence of Fe in the adhesive layer suppresses an excessive reaction between Cu and S and promotes the formation of Cu _1.96 S, which has high strength, at the adhesive interface. That is, the Fe concentration ratio of the plating outermost surface layer 0.01 to 0.03 μm is Fe / (Cu + Zn + Fe) = 2 to 50%.
In this case, good adhesion with rubber can be obtained.

The reason for containing Fe in the present invention is as follows.
This is obtained from the above-mentioned finding that Cu _x S having high strength, specifically Cu _1.96 S, is easily generated. That is, it is considered that the presence of Fe in the brass has an action as a kind of reaction accelerator for producing Cu _1.96 S at the interface between the brass plating and the rubber. Further, in the adhesiveness between the steel wire and the rubber of the present invention, a brass-plated drawn material is embedded in a tire in the state of a twisted wire in which several are twisted,
The reaction with S in the vulcanization step at about 150 ° C. for 20 to 30 minutes is the most important. In addition, this brass plating is
The layer is Cu-plated, the second layer is Zn-plated on the layer, and diffusion-annealing is performed on the layer to adjust it to a predetermined brass component. In order to contain Fe, a diffusion plating process of plating an alloy of Fe and Zn as a second layer on the Cu plating of the first layer and then performing diffusion annealing to adjust it to a predetermined ternary brass component is performed. May be done. In addition, as described above, in the wire drawing process, the Fe contained in the plating surface layer portion is adjusted to have a certain amount of strain so that an amount corresponding to the area reduction rate is introduced into the brass plating layer from the base steel wire. The Fe content of the outermost surface layer of the plating layer may be adjusted by a combination of these methods. The gist of the present invention is not changed by any of these methods.

S in the rubber is opposite to Cu in the plating.
To the interface_xForms S, but this
x takes various values, but Cu_1.96When S is high strength,
The subject of the present invention is how to stably generate this.
It If the Cu ratio decreases, Cu _1.96It is advantageous for generation to S
It has been found that the content of Fe is increased in the present invention.
This Cu ratio is reduced, and further Cu_1.96To S
It is considered that the reaction acceleration is achieved at the same time. The book
In the invention, when the Fe concentration ratio at the outermost surface position is 2% or less,
Is Cu_xOf S, strong Cu_1.96Insufficient generation of S
Will reduce the adhesive strength. Further, if the Fe concentration ratio is 50% or more
In some cases, Cu, which contributes most to adhesion, is insufficient and adhesion failure occurs.
Wear. Therefore, it is regulated within the range of 2 to 50%. Less than,
The present invention will be described in more detail based on examples.

[0014]

Example A 1.2 mm diameter patented steel wire corresponding to SWRS82A was descaled, neutralized with alkali, and then subjected to Cu plating and Zn plating in that order, and brass plating was performed by a diffusion plating method of thermal diffusion. The Cu plating bath is a pyrophosphoric acid bath, and the Zn plating bath is a sulfuric acid plating bath. The plating composition was Cu / Zn = 65/35. The plating current value is preferably about 10 A / dm ² as a current density. The brass alloy diffusion was performed by heat treatment at 500 ° C. for about 10 seconds in a fluidized bed heat treatment furnace. After plating, wire drawing is performed to a diameter of about 0.9 mm with a dry lubricant, then wire drawing with a wet lubricant (sodium or calcium stearate) at a step reduction ratio of 14% is performed at a speed of 600 m / min to obtain the final wire. The diameter was 0.20 mm, 7 strands were processed, and vulcanization was performed using the rubber prepared from the raw materials shown in Table 1. 150 ° C x as vulcanization conditions
It is a vulcanization treatment for 30 minutes.

[0015]

[Table 1]

The surface Fe concentration was changed by changing the plating thickness during plating. That is, by applying the above-described constant wire drawing strain, the Fe in the background is infiltrated into the plating layer. Adhesion test with rubber is AS
Adhesion strength was measured according to TM standard D2229, and the maximum pulling force and the rubber adhesion rate when the cord was pulled out from the rubber were evaluated by an Instron type tensile tester. Initial adhesion and water resistant adhesion (120 ° C, 95% humidity environment for 6 hours)
It evaluated by the two methods of r). The results are shown in Table 2.

[0017]

[Table 2]

The following is clear from Table 2. In Examples 1 to 4 of the present invention, the Fe concentration ratio at the thickness of the outermost layer of the plating of about 0.02 μm was Fe / (Cu + Zn + Fe) = 2 to 50%, so that the adhesion to rubber is good. In Comparative Example 1, since the Fe concentration was 2% or less and the Cu concentration was high, strong Cu _1.96 S out of Cu _x S was insufficiently produced and the adhesive strength was weak. In Comparative Example 2, since the Fe concentration was 50% or more, Cu, which contributes most to the adhesion, was insufficient and adhesion failure occurred.

[0019]

As is apparent from the above examples, according to the present invention, Fe is contained in the brass plating layer, and the concentration of the outermost surface layer portion thereof is regulated, so that Cu in the vulcanization treatment is treated.
_1.96 S promotes the formation of S, strengthens adhesion with rubber, improves initial adhesion and water-resistant adhesion, and contributes to ease of management of processing conditions, reduction of manufacturing cost and omission of steps. The adhesion of the plated steel wire to rubber has been greatly improved, and its industrial utility value is high.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a Fe concentration ratio and an initial rubber adhesion rate according to the present invention.

FIG. 2 is a chart showing an example of Auger spectroscopic analysis of a plating layer according to the present invention.

Claims (2)

[Claims] 1. An ultrafine steel wire which is used by subjecting a steel wire to brass plating mainly composed of Cu and Zn, and then wire drawing.
Fe is contained in the brass plating layer, and the Fe concentration in the outermost layer of the brass plating is Fe / (Cu + Zn + Fe) = 2 to 5
A brass-plated steel wire having good adhesiveness to rubber, which is characterized by 0%. 2. The brass-plated steel wire having good adhesiveness to rubber according to claim 1, wherein the brass-plated outermost layer is 0.01 to 0.03 μm from the plated surface.