JPS61212368A - Rust-preventive coating method for plated wire rod - Google Patents

Abstract

PURPOSE:To form a uniform and thin film on the surface of a plated wire rod by coating a rust preventive liq. consisting essentially of an org. synthetic resin and whose viscosity is regulated to a specified value on the horizontally traveling plated wire rod, removing the liq. on the lower side and then curing the liq. CONSTITUTION:When a rust-preventive coating is applied to a zink-plated or aluminum-plated wire rod to control the corrosion of the plated metal, a rust- preventive liq. consisting essentially of an org. synthetic resin and whose viscosity is regulated tp 5-60 centipoise is coated on a horizontally traveling plated wire rod 1 by a coating device 2. Then the surplus coating liq. on the lower side of the plated wire rod is removed by a wiper 3 under the wire rod. Then the coated wire rod is immediately introduced into a heating and drying furnace 4 and the liq. is dried and cured to form a rust-preventive film. A plated wire rod having a uniform film is thus formed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for anti-corrosion coating of plated wire rods, and more specifically, the present invention relates to a method for coating plated wire rods with anti-rust coating, and more particularly, the present invention relates to a method for coating plated wire rods with anti-corrosion coating, and more specifically, the present invention relates to a method for coating plated wire rods with anti-rust coating, and more specifically, the present invention relates to a method for coating plated wire rods with anti-corrosion coatings, and more specifically, the present invention relates to a method for coating plated wire rods with anti-rust coating. This invention relates to a rust-preventive coating method that completely inhibits corrosion.

(Prior art) Conventionally, plating applied to steel wires can be roughly divided into brass plating for steel cords, copper plating for welding wires, and zinc plating applied to gilt copper, ropes, cables, etc. Or there is aluminum plating. Among these, zinc-based and aluminum-based plated wires are usually used in the atmosphere, fresh water, or seawater, so the corrosion resistance of the plated wires is mainly determined by the type of plated metal and its thickness.

However, after the plated wire is manufactured, it may be stored in a warehouse or outdoors for several months or even several years until it is actually used. In such cases, oxidative corrosion of the plated metal progresses during storage of the plated product due to dew condensation, rainwater, etc., and corrosion products adhere to the surface, significantly reducing its commercial value.

Currently, wax coating is generally applied to prevent this type of corrosion, but wax coatings do not exhibit sufficient rust-preventing power. In addition, in recent years, for example, there has been developed
Publication No. 786, Publication No. 56-5313, Publication No. 54.22
There is a tannic acid treatment known from Publication No. 781.

This treated film can relatively suppress corrosion in environments where rainwater does not come into contact with it, such as in factories or warehouses, but if it is exposed to rainwater outdoors, the anti-corrosion ability will decrease in a relatively short period of time. There are drawbacks.

Also, for example, a water glass-based anti-corrosion film as disclosed in Japanese Patent Publication No. 55-305-93 has excellent corrosion resistance itself, but because it is an inorganic film, it has poor adhesion to plated metal. However, when bending the plated wire, a part of the coating becomes powdery and falls off.

In addition, colored coating on plated wire (JIS-03542)
There are already products that have been treated with this, but these have thicker coatings and are corrosion resistant for long periods of time outdoors.

For example, vinyl chloride coated iron wire (JIS-03
There are those coated with vinyl chloride with a thickness of 150 μm or more, such as No. 543). However, these are all means for providing a permanent thick coating on steel wire,
It is not intended for rust prevention during storage until the plated wire is used.

That is, in order to meet this purpose, it is not necessary for the coating to be thick at all, and a thin anticorrosion coating is sufficient. Furthermore, the coating process does not need to be carried out in a line exclusively for painting, and it is sufficient to carry out the process at the end of the plating line, so it is required that the process be carried out in a relatively small space.

An effective way to uniformly form such a thin film is to move the wire vertically while applying the coating, but in Japan, wire plating manufacturers do Currently, the plating line is installed in a horizontal direction due to its height.

However, in equipment where the plated wire runs horizontally, even if an anti-rust coating liquid is applied, the coating liquid will drip from the top of the line to the bottom over time, causing damage to the surface of the plated line. It is not easy to form a uniform anti-rust film.

(Problems to be Solved by the Invention) The present invention provides a method for coating a plated wire rod having a uniform anti-rust coating.

(Means for Solving the Problems) The inventor of the present invention has investigated rust prevention measures during storage of plated wires used for gilt copper, ropes, cables, etc. As a result, the present inventors have developed a method for preventing plated wires running horizontally from having a predetermined viscosity. Immediately after application, the coating solution below the plated lines is removed, and the film is quickly cured in a heating drying oven. It was discovered that a uniform thin film could be formed.

Next, the present invention will be explained in detail.

First, in the present invention, plated wire refers to
Refers to 8φ steel wire coated with zinc or zinc-based alloy plating, or aluminum-based plating.

FIG. 1 is a diagram schematically showing the coating process of the present invention, in which a plating line 1 running in the horizontal direction is located on the left side, which is the entrance side of the figure, and on the exit side of the plating line. After applying the rust preventive liquid using the coating device 2, the plated wire 1 is coated.
A wiper 3 provided below removes the excess coating liquid below the plating line and immediately introduces it into a heating drying oven 4 to dry and harden the coating to form a rust preventive coating.

The figure also shows the relationship of the thickness of the coating liquid on the surface of the plating line 1 with respect to the passage of time in the process, and in the figure, the relationship between the thickness of the coating liquid on the surface of the plating line 1 is shown. The film thickness is represented by 5, and the film thickness on the upper side is represented by 6. As shown in the figure, immediately after application, the coating liquid on the upper side drips downward, so the lower coating gradually becomes thicker, while the upper coating gradually decreases. By removing the lower coating solution, the lower film is once reduced considerably. However, as the coating liquid on the upper side continues to drip down, the thickness of the upper and lower layers gradually approaches each other, and when the thicknesses of the upper and lower layers become equal, the coating begins to harden in the heating drying oven. This means that the film thickness will be uniform all around.

Next, as a coating liquid for forming a rust-preventive film, the film after coating has excellent adhesion to the plated metal.
Use a material whose main component is an organic synthetic resin that forms a film that does not easily fall off due to condensation water, rainwater, etc. An organic solvent or water may be used as the solvent, but in consideration of the working environment of existing plating lines, an aqueous solvent system is more advantageous in terms of handling. The main organic synthetic resins include acrylic, epoxy, polyamide, imide, polyethylene, vinylidene chloride, vinyl acetate, polycarbonate,
Resins such as styrene, olefin, fluorine, phenol, melamine, and polyester can be used.

The appropriate concentration of the organic synthetic resin is 5 to 40%. If this concentration is less than 5, the energy loss required for evaporation of the solvent in the heat drying step after coating becomes large, and the time required to form a film becomes long, which is disadvantageous to the formation of a uniform thin film.

Moreover, if it exceeds 40%, the viscosity of the coating solution will change significantly, and it will tend to gel during storage. Furthermore, even slight evaporation of the solvent during coating operations tends to increase the viscosity, making it unsuitable for continuous operations.

Other components of the anti-rust coating solution may not be particularly necessary, but they may also be used to improve the corrosion resistance, adhesion, and hardness of the anti-rust coating.
Inorganic colloidal substances, pigments, silane coupling agents, phosphoric acid or phosphate compounds, ammonia, oxides of alkaline earth metals such as amines, surface activity, etc. for the purpose of coloring and improving the activity of matted metal surfaces. Agents etc. can also be added.

This coating liquid is applied to the surface of the plating line running in the horizontal direction, but in order to form a thin and uniform film, it is necessary to adjust the viscosity of this coating liquid to a range of 5 to 60 centimeters. It is.

If the viscosity is less than 5 centivoise, the moving speed of the liquid on the wire surface will be high and the upper coating will tend to be too thin, making it difficult to obtain a uniform coating. If it exceeds 60 cm, the fluidity of the solution will be slow and the film thickness on the upper side of the wire surface will become too thick, making it difficult to obtain the thin film that is the object of the present invention. After the coating liquid on the lower side is removed, the coating liquid drips down from above the line, and it takes a long time to form a uniform thickness, making it difficult to adjust the film thickness in the manufacturing process.

The coating liquid described above is applied to the surface of the tightened line at the exit side of the plating line to clean the surface. The means for applying the rust preventive liquid to the horizontally running line can be carried out by dipping or flow coating. At this time, it is desirable to keep the wire temperature as constant as possible immediately before coating; if it is not constant, the viscosity of the coating liquid will change depending on the temperature, and the fluidity on the wire surface will fluctuate, causing variations in the amount of film.

After coating, it is possible to adjust the coating amount by wiping the entire surface of the line with a die or gas stream, but as described in Fig. 1, after coating the liquid, the upper side of the line may The coating liquid drips downward, so apply the coating so that the thickness above the line is constant, and after a certain period of time, remove the coating liquid only below the line by wiping or other means, and immediately introduce it to a heating drying oven. Furthermore, as time passes, the coating liquid on the upper side of the wire drips down, and when the entire circumference of the wire is coated uniformly, the coating film is cured to complete the formation of the anti-rust film.

In order to carry out this coating operation, it is desirable that the line temperature before the coating surface be maintained. If the temperature is less than 40°C, it takes a long time to cure the coated film. Moreover, if it exceeds 80°C, it is not preferable because it will have an adverse effect on the stability of the resin in the coating liquid. Of course, it is desirable to keep the temperature of the coating liquid constant.

In this way, after coating, the excess liquid below the line is removed by a wiper that removes the liquid by contacting the line with a roll, rubber sponge, sheet molded product, etc., or a non-contact wiper that sprays a gas stream. However, since the degree to which the liquid can be removed varies depending on the material and structure of the wiper, the fluidity of the liquid should be taken into consideration, and after removal, the application equipment should be adjusted to suit the point at which the film hardening begins. It is sufficient to install wiper equipment and heating drying equipment and determine their conditions.

Incidentally, it goes without saying that the thicker the rust-preventive coating, the better the corrosion resistance, but as mentioned earlier, the purpose of the present invention is to prevent rust while the wire is being stored. For this purpose, a coating thickness of approximately 3 μm is required. However, for that purpose, a coating thickness exceeding 15 μm is not necessary.

To give an example of the conditions for forming a film with such a thickness, a coating liquid with a viscosity of 5 to 60 centipoise as described above is applied to the plating line, and after removing the lower coating liquid with a wiper, a coating liquid with a viscosity of about 0.5 to 60 centipoise is applied to the plating line. After a few seconds, it is introduced into a heating drying oven and the temperature of the atmosphere inside the oven is adjusted within the range of 150 to 600°C, thereby making it possible to form a uniform cured film with a thickness of about 3 to 15 μm. At this time, the film temperature is 105~1
It is desirable to set the drying conditions so that the temperature is within the range of 50°C.

(Example) In a hot-dip galvanizing line, 30 mm was applied to a 50φ steel wire.
02 After galvanizing the wire, the surface was cleaned with alkaline degreasing and exposed to sunlight.The moisture on the wire surface was removed using a hot air blower, and the wire temperature was set to 60℃, and the wire temperature was maintained at 40℃. Acrylic resin emulsion with a concentration of 3% 51
02 A rust preventive liquid made of colloidal silica was applied with a flow coater after adjusting the viscosity of the coating liquid with C, M, and C.
After performing the wiping shown in the table, coating was carried out under various conditions to obtain a rust-preventive film having the film thickness shown in the table.

In the same table, numbers 1 and 4.6 are comparative examples, and numbers 2 and 3.5 are examples of the present invention.

These anti-rust coatings were evaluated by the following method.

Test method 1 Corrosion resistance test A test wire was inserted at right angles between two stainless steel wires with a diameter of 5φU stacked in parallel, a load of 5 Kp was applied between the stainless steel wires, and the test wire was moved at a speed of about 3 m/min.

After pulling out at a speed of
) after 3 weeks, the rate of white rust on the wire surface was examined, O...no white rust occurred Δ...1 to 10% occurrence x...
-Evaluated as necrotic in 10% or more.

2 Uniformity test of anti-rust coating The cross section of the coated test wire was magnified 400 times using an optical microscope, the coating thickness was measured, and the uniformity of coating was determined by the ratio of the coating thickness above the line to the coating thickness below. I checked the money.

The results are shown in Table 1.

As shown in Table 1, on the horizontally running mating line,
Immediately after applying a rust-preventing solution mainly composed of organic synthetic resin adjusted to a viscosity of 5 to 60 centipoise, the coating solution below the plating line 1 is removed, and then immediately introduced into a heating drying oven to form a film. It can be seen that by curing and forming a thin and uniform anti-rust film. On the other hand, coating methods not according to the present invention are not suitable for practical use because they fail to provide a suitable film thickness or lack uniformity of the film.

(Effects of the Invention) As is clear from the above embodiments, according to the present invention, anti-rust coating of plated wire can be carried out by relatively simple means and without extensive modification of existing equipment. If possible, the industrial effects would be extremely significant.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing the coating process of the present invention. 1... Plating wire, 2... Coating b device, 3
... Wiper equipment - 4 ... Heating drying oven, 5 ... Lower film thickness, 6 ... Upper film thickness.

Claims (1)

[Claims] An anti-corrosion solution mainly composed of organic synthetic resin adjusted to a viscosity of 5 to 60 centipoise is applied to the surface of the plating line running in the horizontal direction. Immediately after application, the coating liquid below the plating line is removed. A method for coating a plated wire rod with anti-rust properties, which comprises immediately introducing the wire rod into a heating and drying oven to form a rust-preventive film.