JP2950701B2 - Brass plating with β brass dispersed in α brass with excellent workability and adhesion to rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new brass plating for improving the adhesiveness to rubber and the workability of a material used for reinforcing rubber by applying a brass plating.

[0002]

2. Description of the Related Art There are many techniques for improving the strength and durability of rubber by embedding a reinforcing material in rubber.
Of these, composites of rubber and steel are used for automobile tires,
It is applied to high pressure rubber hoses, conveyor belts, etc. Since steel and rubber have poor adhesion, there are many products that are formed by applying brass plating to steel and utilizing a chemical bond between Cu in the brass plating and S in the rubber. In the brass plating, the conventional alloy plating from a cyanide bath is reduced due to a problem of pollution, and is replaced by a diffusion plating method of performing thermal diffusion after performing Cu and Zn plating independently. In this diffusion plating, a concentration gradient occurs in the Cu and Zn in the depth direction, and the Cu concentration on the surface tends to be lower than that in the bulk, but tends to improve the adhesiveness to rubber. Therefore, JP-A-62-1
48530, the Cu concentration of the brass plating surface is 25 to 4
By adjusting the amount to 0% by weight, the adhesion to rubber was improved. However, it is not described whether or not a β brass structure exists near the surface.
If the brass mass is not a tissue dispersed in alpha brass,
In order to limit the surface Cu concentration after wire drawing as described above, precise plating solution management technology such as plating solution composition, flow rate, and contamination with impurities, and processing condition management technology are required. The effect on surface area, aging of the die, deterioration of the lubricant, and heat generation by wire drawing is large, so that the management cost is actually increased. In Japanese Patent Application Laid-Open No. 62-28235, a steel cord surface is irradiated with an electron beam to modify the surface to be amorphous. ≤500,200-3
00log (t) ≦ T ≦ 500-200log (t), and by performing a heat treatment under the conditions of (T: heating temperature (° C.), t: heating time (second)) to increase the amount of zinc oxide on the surface, Improved adhesion. However, they have the disadvantage that the number of steps is increased and the cost is increased accordingly.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems of the prior art, such as the increase in adhesion between brass plating and rubber, workability, manufacturing cost, and the number of steps. In brass plating mainly composed of Zn,
A process characterized by dispersing a β brass lump having a maximum size of 0.01 to 2 μm in an α brass, and wherein the β brass lump is located within 70% of a plating thickness in a thickness direction from a plating surface. Provided is a brass plating in which β brass having excellent properties and adhesion to rubber is dispersed.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a brass plating mainly composed of Cu and Zn, wherein a .beta. Brass block having a maximum size of 0.01 to 2 .mu.m is formed in an .alpha. And a β brass lump is positioned within 70% of the plating thickness in the thickness direction from the plating surface.

[0005]

The operation of the present invention will be described below. The brass plating of the present invention can improve the adhesion to rubber. Specifically, in brass plating mainly composed of Cu and Zn, a β brass lump having a maximum size of 0.01 to 2 μm is dispersed in an α brass, and the β brass lump is plated in a thickness direction from a plating surface. It is located within 70% of the thickness. As a result, the effect of improving the adhesion to rubber is exhibited even after the subsequent processing. The reason is that the β brass mass is within 70% of the surface side and is wrapped in soft α brass and remains on the surface side.

Hereinafter, the reasons for limitation of the present invention will be described. The brass plating mainly composed of Cu and Zn is not necessarily a brass plating of only Cu and Zn. Elements such as Co, Sn, and Ni for improving corrosion resistance, Pb for improving machinability, and Fe and Mn for improving mechanical properties are often added. The third element and the fourth element are added. The meaning includes the brass to which is added.

The reason why the maximum size is limited to 0.01 to 2 μm is that β brass particles having a size of 0.01 μm or less have a small effect of contributing to adhesion to rubber, and a size of 2 μm or more tends to cause deterioration of workability. is there. The reason why the β brass mass is limited to 70% or less of the plating thickness in the thickness direction from the plating surface will be described below. Adhesion to rubber is a reaction between the surface of the brass plating and the rubber, and although β-brass is more present on the surface, the adhesion is better. This is because β brass is a structure having a Cu ratio with good adhesion to rubber, and does not easily undergo transformation if heat generation during processing is suppressed to a low temperature of 200 ° C. or less. Therefore, it is better that the β brass is present as intensively as possible on the surface side so that the adhesiveness to the rubber is good.
However, when the thickness exceeds 70% of the plating thickness from the surface in the thickness direction, the workability is likely to deteriorate due to the β brass having poor cold workability.

Further, the reason why the β brass mass is dispersed in the α brass is that the α brass has a good cold workability, so that it becomes a medium having good β brass even during processing. An example of the brass plating structure of the present invention is as shown in FIG. 1, in which β brass lump 2 is dispersed in α brass 1 and located within 70% of the plating thickness in the thickness direction from the surface.

The production method is not particularly limited,
As an example, there is a method of performing thermal diffusion after performing Cu plating and Zn plating. The present inventors examined various plating and thermal diffusion conditions, and when the plating thickness ratio, heat treatment temperature, and time in a specific range were limited, a β brass mass was formed in the plating layer, and the presence state was controlled. I found that I could do that.

[0010]

EXAMPLES A 1.2 mm diameter patented steel wire corresponding to JIS SWRS82A was descaled, and then subjected to Cu plating and Zn plating sequentially. Plating was performed with Cu / Zn = 65/35 and a total thickness of about 2 μm. And 350-550 in the fluidized bed
The resultant was subjected to thermal diffusion at 1 ° C. for 1 to 30 s to perform brass plating. After that, wet drawing was performed at a step reduction ratio of 14% at each step, the final wire diameter was set to 0.2 mm, and the adhesion to rubber was evaluated after twisting seven wires. The Cu plating bath is a Cu pyrophosphate bath, and the Zn plating is a Zn sulfate plating bath. The rubber composition used for the evaluation of the adhesion to rubber is shown in Table 1.

[0011]

[Table 1]

The vulcanization conditions are 150 ° C. × 30 min. The adhesive strength was measured by measuring the maximum pulling force and the rubber adhesion rate when the cord was pulled out of the rubber by an Instron type tensile tester. The dimensions and location of the β brass were measured with a transmission electron microscope. Further, in order to evaluate the workability deterioration by mechanical properties, a 0.2 mm drawn wire was subjected to a hunter fatigue test to determine the fatigue limit. Table 2 shows the results.

[0013]

[Table 2]

Comparative Example 1 has a maximum β brass mass size of 0.01 μm.
m, the effect of contributing to the adhesion to the rubber was small, and poor adhesion occurred. In Comparative Example 2, since the maximum size of the β brass mass was larger than 2 μm, the adhesiveness to rubber was good, but the fatigue limit of the drawn material was reduced due to deterioration in wire drawing workability. Comparative Example 3 shows that although the β brass mass is present in the thickness direction from the plating surface exceeding 70% of the plating thickness, the adhesiveness to rubber is good, but the wire drawing material is deteriorated due to deterioration in wire drawing workability. The fatigue limit decreased.

On the other hand, it can be seen that the present invention is excellent in both adhesion to rubber and fatigue characteristics after wire drawing. Further, in this embodiment, a steel wire is used as a material, but the same effect as in this embodiment can be expected as long as a brass plating is applied to other metal materials such as a plate material and a tube material.

[0016]

As is clear from the above embodiments, the present invention greatly improves the adhesiveness and workability between the brass plating and the rubber, and has an industrial advantage because no additional steps are required and the cost is low. Is big.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a brass plating structure of the present invention.

[Explanation of symbols]

 1 ... alpha brass 2 ... beta brass 3 ... base

Claims (2)

(57) [Claims] 1. A brass plating mainly comprising Cu and Zn, wherein a β brass lump having a maximum size of 0.01 to 2 μm is dispersed in an α brass. 2. The brass plating according to claim 1, wherein the β brass mass is located within 70% of a plating thickness in a thickness direction from a plating surface.