JPS5858297A - Plating method for steel wire for tire cord - Google Patents

Abstract

PURPOSE:To enhance the plating yield and to easily control the composition of plating by subjecting a steel wire to alternate copper plating and zinc plating plural times, carrying out copper plating to form the outermost layer, and diffusing the plated layers by heating to convert plus state. CONSTITUTION:A rough steel wire 1 is heat treated through a heating furnace 2 and a lead quenching vessel 3, and it is pretreated through an electrolytic pickling vessel 4, a washing vessel 5, an alkali cleaning vessel 6 and a washing vessel 5. The treated wire 1 is subjected to the 1st copper plating in copper plating vessels 17, washing in a washing vessel 5, the 2nd zinc plating in a zinc plating vessel 18 and washing in a washing vessel 5. After repeating alternate copper plating and zinc plating necessary times, copper plating is carried out in a copper plating vessel 17 to form the outermost layer. The plated wire is washed in a washing vessel 5 and heated to a suitable temp. with electric heaters 9 to carry out diffusion, and the wire is coiled around a coiler 10. Thus, the mutual diffusion is facilitated, the diffusion is carried out at a low temp. in a short time, and the composition of the plating is easily controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a positive plating method for steel wire for tire cords.

Tire cords are embedded in rubber and used for a long time, but in order to provide adhesion to the rubber, the entire surface of the cord is coated with positive plating, and the cord is manufactured through a wire drawing and stranding process.

Conventional positive plating methods include 7 containing copper and zinc.
A so-called alloy plating method has been used in which copper and zinc are simultaneously deposited using an annealing bath.

However, the cyanide bath is highly toxic and harms the working environment, and pollution control measures such as the hydrothermal solution treatment are a major problem in production, and furthermore, it has the disadvantage that strict control is required to control the plating composition.

Therefore, in recent years, as shown in Fig. 1, a method has generally been used in which copper plating and zinc plating are applied on top of the copper plating, followed by heating to cause the copper and lead to mutually diffuse, thereby forming an alloy. There is.

After passing through an alkaline cleaning tank 6 and a water washing tank 5, it is pre-treated, then treated with copper plating tank 7, where it is then plated, passed through a water washing tank 5, and galvanized in a galvanizing tank 8, and after washing with water in a water washing tank 5, it is heated by an electric heating device. After being heated to around 500'C by 9 and subjected to a diffusion treatment, it is wound up by a winding machine 10.

A pylori/acid copper bath and a zinc sulfate bath are used in the copper plating bath 7 and the zinc plating bath 8, respectively, since they cause little pollution problems.

A schematic cross-section of the wire before diffusion treatment in this method is shown in FIG. 2, in which there is a copper plating layer 11 on the steel cable wire 1 and a zinc plating layer 12 on the outermost layer. In the case of 1.25111#f steel cable wire, the thickness of the plating layer is usually 4 to 5 μm, of which the copper plating layer is 3
．． It is around 5 μm. When the wire in this state is heated at around 500°C for about 2 to 3 seconds, copper and zinc will interdiffuse.
Uniformly alloyed.

This method has advantages such as no pollution problems and easy control of the plating composition, but unless the heating is controlled at around 500°C and the heating is done in a device completely heated with inert gas. , the plating layer with zinc on the surface is oxidized, and it falls off during the subsequent wire drawing process, which also hinders the lubricating effect, and the high vapor pressure of zinc during heating causes evaporation. There are issues such as ease of use. Therefore, at the time of plating, an extra amount must be applied to allow for drop-off due to oxidation and evaporation of zinc.

On the other hand, the main reason for applying positive plating to tire cords is to impart adhesion to rubber, and the composition of the outermost surface of the plating is most important for this purpose. In other words, the optimal plating surface differs depending on the composition of the five rubbers, but generally the ratio of copper to zinc is 7:3 to 3.
It is said to be 6:4.

In the case of the method described above, zinc is in the outermost layer before diffusion, so unless the diffusion is thoroughly and thoroughly carried out, the outermost surface will not have the above composition, and the temperature must be 500 - There is a problem that Ca is high and therefore oxidation and evaporation are likely to occur.

The present invention was made to solve all the above-mentioned problems, and consists of repeating copper plating and zinc plating two or more times alternately,
Copper plating on the outermost layer facilitates thermal diffusion of copper and zinc, prevents evaporation of zinc, and prevents oxidation and shedding of the plating layer, improving plating yield and improving plating composition. This is a method for plating steel wire for tire cords (L-) that can easily control the number of tires.

In the present invention, copper plating and zinc plating are repeated two or more times on a steel wire to obtain the outermost layer of gold copper plating, and then the plated steel wire is heated and diffused, thereby completely dissolving the entire plating layer. This is a method of plating steel wire for tire cords, which is characterized in that it becomes positive.

The first layer of plating in the present invention may be either copper plating or zinc plating, and in the case of copper plating, copper plating,
After alternately repeating zinc plating, the outermost layer of copper plating may be applied. Note that the adhesion is better when the first layer is gold-copper plating.

Hereinafter, the present invention will be explained by examples using all the drawings. FIG. 3 is a block diagram for explaining an embodiment of the method of the present invention. In the figure, the same reference numerals as in FIG. 1 indicate the same parts.

In the figure, the steel cable lid is heat treated and pretreated in the same manner as in FIG.
The first layer of copper plating is applied, then passes through the washing tank 5 and then the galvanizing tank 1.
A second layer of zinc plating is applied in step 8 and washed in a washing tank 5. Thereafter, copper plating in the copper plating tank 17 and zinc plating in the galvanizing tank 18 are repeated alternately a required number of times. Finally, after the outermost layer is copper plated in the copper plating tank 17, it is washed with water in the water washing tank 5, and then the electrical heating device 9
After being heated to an appropriate temperature and subjected to diffusion treatment, it is wound up by a winding machine 10.

Note that the above-described alternating repetition of copper plating and zinc plating may be repeated two or more times. In the first layer, copper plating is performed three times and zinc plating is performed twice. A schematic cross-section of the wire before diffusion treatment in this method is shown in FIG. The bath is preferably a birophosphate steel bath, a copper sulfate bath, etc., which cause less pollution problems, but is not limited thereto. Further, the zinc plating bath is preferably a sulfuric acid bath, a zinc bath, etc., which cause less pollution problems, but is not limited thereto.

The plating method according to the present invention configured as described above has the following effects.

I9 Copper plating and zinc plating are alternately applied on the steel wire.
Since plating is repeated several times or more, each layer with V) can be made thinner, and when heated and diffused to 7'C, the diffusion distance is short, so alloying can be achieved at a lower temperature and in a shorter time. Usually 45
．． A temperature around 0°C is sufficient.

■ As mentioned above, heating is required at a lower temperature and in a shorter time, and since the outermost layer is a copper plating layer, oxidation of the plating layer,
Since there is less evaporation of zinc and less oxide falling off during wire drawing, the plating yield is the same as above, and the final plating composition can be easily controlled.

■ Since the outermost plating layer is a thin copper layer, the outermost surface composition tends to become a pot-rich alloy with good adhesion to rubber through diffusion treatment, so complete diffusion of the plating layer is performed as in the conventional method. It is not necessary, and a diffusion layer can be obtained by heating at a lower temperature and for a shorter time.

Example: By the method shown in Figure 1, copper plating and zinc plating were alternately repeated on a 1.25 f steel cable wire to form a steel plating layer 3.
After forming two galvanized layers and a copper plating layer as the outermost layer, a diffusion treatment was performed at 460° C. for 2 seconds using an electric heating device #9 (hereinafter referred to as the present invention).

For comparison, 1.251 fl was obtained by the method shown in Figure 1.
After plating one layer of copper plating and one layer of zinc plating on the pure steel cable, it was heated at 520°C for 2 hours using direct heating equipment #9.
A sample C (hereinafter referred to as Comparative Example h1) which was subjected to a diffusion treatment for 2 seconds, and a sample C (hereinafter referred to as Comparative Example &2) which was subjected to a diffusion treatment at 480° C. for 2 seconds were prepared.

In addition, the total plating adhesion 11 in each plated wire was adjusted to 12 so that it was 4 parts per kg of steel wire, and the ratio of plated copper to plated zinc was 7 = 3).

Each of the plated steel cables obtained was drawn by a 16-die wire drawing machine.
The wire is drawn to 25111Rf, and then 5
I made all the tire cords of real twist (IX5X0.25).

The plating compositions immediately after plating (before diffusion treatment) and after twisting are as shown in Table 1.

Sandwich each tire cord and cord sample between two unvulcanized rubber sheets and pressurize this 7"L.
After sulfurizing the sample, it was peeled off along the cord section and its adhesion to rubber was evaluated. The results are shown in Table 1.

In addition, the evaluation of adhesion with rubber is given as 10 points if the +0096 Conym layer is resistant to the surface of the cord after being peeled off, and 0 points if the entire cord surface is exposed, and scores in between are proportional to the surface rubber adhesion rate. and gave a score.

Table 1 Ni ≦ (E) 9 layer% indicates stiffness of 1 (jl) per 2 steel wires.

From Table 1, it can be seen that the product according to the present invention has sufficient adhesion even though the diffusion temperature is as low as 460°C compared to the comparative example, and the yield of the plating layer is approximately 100°C within the analytical error range. It can be seen that it shows %.

On the other hand, the comparative example AI (diffusion temperature 520°C) shows sufficient adhesion, but oxidation and shedding of the plating layer due to diffusion and wire drawing, and evaporation of zinc were observed, and the loss of the tl plating layer was 0.3 f.
/ is 9.

In addition, in Comparative Example &2, the total diffusion temperature was lowered to 480°C, so
Oxidation of the plating layer, shedding, evaporation of zinc, etc. are lower than &1, but the important adhesion is extremely poor with a rating of 3.

From these, according to the method of the present invention, the reciprocal diffusion is facilitated by multilayer plating of a thin copper layer and a thin zinc layer, and since the outermost layer is a copper layer, the diffusion temperature can be low, improving the plating yield. At the same time, it was found that the plating composition could be easily controlled.

[Brief explanation of the drawing]

Figure 1 is a block diagram for explaining an example of a conventional method for producing steel wire for tire cords, and Figure 2 (2) schematically shows a cross section of the wire before diffusion treatment in the method shown in Figure 1. It is a diagram. FIG. 3 is a block diagram for explaining an embodiment of the method of the present invention, and FIG. 4 is a diagram schematically showing a cross section of a line before diffusion treatment in the method shown in FIG. 3. 7.17...Copper plating tank, 8.18...Lead repellent plating tank, Agent: Patent attorney Hide Aoki Minoru d

Claims (1)

[Claims] (1) After plating the steel wire by repeating copper plating and zinc plating two or more times alternately to obtain the outermost layer of gold-copper plating, the plated steel wire is heated and diffused to make the plating layer positive. All features include multiple ways to make steel wire for tire cords.