JPS6082697A - Method for coating article - Google Patents

Abstract

PURPOSE:To enable the use of a hanger from which a plated article is suspended in different stages and to combine all the stages in a straight line by subjecting the plated article to coating by electrodeposition and baking while suspending the article from a hanger covered with fluororesin. CONSTITUTION:The skeleton of a hanger is covered with fluororesin except the part contacting with a power supply bar and the part holding an article. An article to be plated is suspended from the hanger and electroplated. The electroplated article is coated by anionic electrodeposition without detaching from the hanger. The plated article is then baked in the suspended state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention covers the entire process of forming an anionic electrodeposited coating film on the footing of an article, especially after applying metal plating.
By making it a straight process, the painting process was streamlined.

Metal-plated articles are coated with synthetic resin paint in order to reduce the luster characteristic of metals and to prevent corrosion of the metal plating layer. In this case, the electrodeposition coating method is recommended from the viewpoints that the coating thickness can be controlled and that the details of the fine irregularities on the surface of the article can be reproduced without damaging them.

As is well known, in order to electrolytically plate a metal on the surface of an article, the article to be plated is attached to a conductive hanger, suspended in an aqueous solution containing a specified metal salt, which is an electrolytic bath, and energized. A plating layer of a predetermined thickness is formed on the surface of the article. In the electrodeposition coating process, the article to be coated is similarly attached to a hanger, and while it is charged (+), it is passed through an anion rL dye bath cloth that is charged (-), thereby coating the surface of the article. Adsorbs paint electrically. It is then removed from the paint bath and subjected to a heat curing process of the paint vehicle called baking. This processing condition is usually 160 to 2
00°C for 30 minutes, which is a fairly high temperature and long time.

As can be seen from the process described above, if this process is to be performed most efficiently and rationally, it is necessary to use the same material throughout the entire process, including the electrolytic plating process and the electrodeposition coating process or baking process. Use the hanger of
It is important not to change the parts during each process. That way, the whole process will be straightly combined, and the effort will be 2
It is clear that this contributes to saving time and other expenses.

-However, such a combination of processes is actually unknown. This is because the hangers used in the electrolytic plating process are usually made of copper, to which are soldered the claws for attaching objects made of stainless steel wire or via 7 kneaded, and the parts outside the claws, which are the contact points, are made of polyester. It is covered with a film of thermoplastic resin threads made of vinyl chloride or polyolefin.

This deterioration is an indispensable condition for reducing power consumption and increasing efficiency in electrolytic plating.
It is impossible to omit that. Moreover, its heat resistance temperature is only 140°C at most. Therefore, it is not possible to subject the hanger used for electrodeposition coating to the above-mentioned baking treatment while still hanging on the hanger. Because of the heating process, the coating.

This is because it will dissolve.

In order to solve this problem, the present inventors first applied a specific pre-treatment solution such as 5 to 90% organic solvent, 5 to 90% acid, while still attached to the hanger, the article after electrodeposition coating. , a low-temperature curing method (Special Crimes Showa 58-83795
However, since a new step of immersion in the above-mentioned pretreatment liquid is added, it is still not a sufficient countermeasure. In addition, as another method, the article after electrodeposition coating can be coated with a wire attached to the hanger for 80 to 10 minutes before baking.
．． After setting at 00°C, the baking jig was replaced by 1↑ and baking was performed, but this also involved one extra step and resulted in a long chain.

The present invention has been made from the above viewpoint, and the article to be plated is hung silently on a hanger coated with fluororesin, electrolytically plated with metal, and then The present invention is characterized in that an article is subjected to anion electrodeposition coating without being removed from the hanger, and the coated article is subjected to a baking treatment without being removed from the hanger.

Articles that should be plated here include iron, copper, aluminum and other metals or alloys, and articles made of various resins such as polyolefin with 11 properties, ABS tM resin, nylon, and polyester, such as electronic equipment. Electrolytic baths, electrolytic conditions, or types of resins for anionic electrodeposition coatings, such as knobs, handles, push buttons, etc., to avoid electrolytic plating of metal on such items.9 Electrodeposition conditions, and baking conditions. However, it is no different from the previous one.

However, since the application of anion electrodeposition coating to the surface of the metal-plated article is a technique invented by the present inventors, a few additional comments will be made just in case. That is, the paint for anionic electrodeposition used for coating articles after plating is water-based, that is, water-soluble or water-dispersible resin 2, such as acrylic-mepmine resin, epoxy-melamine resin, alkyd-melamine resin, polyester resin. The main component is an aqueous resin selected from the following, and contains some solvents, neutralizing agents, etc., and is itself known.

For electrodeposition coating, use the above paint in an electrolytic bath to reduce the solid content to 5.
~30%, and the plated item is used as the @ pole.
10-2 with carbon plate or stainless steel plate as the counter electrode
00V, electricity is applied for 3 seconds to 3 minutes.

The hanger used in the present invention is not particularly different from conventional hangers in its essence. In other words, the article is attached to the copper rod.
It is fixed to the branch by mechanically attaching it with a piano wire or stainless steel wire of an appropriate length, wrapping it around it, inserting it with a screw, or by using welding, thermal spraying, etc. other than soldering. It is something.

The fluororesin used to coat such a hanger-like surface includes tetrafluoroethylene resin, trifluorochloride ethylene resin, tetrafluoroethylene-67 twig brobylene copolymer resin, and the like. The melting points are 327°C, 210-212°C, and 285°C in the order listed above. In any case, it is sufficient that it can withstand the maximum temperature of about 180° C. to which the present invention is continuously applied. Note that if we focus only on #thermal properties, various heat-resistant resins such as boniphenylene oxide, polysulfone, polyimide, and polybenzimidazole come into consideration, but in the method of the present invention, fluororesins are particularly effective. The reason for this is that it surpasses any of these heat-resistant resins and has the properties required for an electrolytic jig, such as a hanger, such as zero water absorption and moisture permeability.
It is chemically inert, which means it is resistant to acids, alkalis, and solvents, which are especially important for plating, and it also has extremely high electrical insulation properties, non-stick properties, and low friction properties. It is power and ra.

In order to coat the hanger tube with 8"L of such fluororesin, it is appropriate to use a paste extrusion method based on the shape of the hanger. That is, among fluororesin, it is appropriate to use a paste extrusion method called fine powder. The powder is made into a paste using solvent naphtha, etc., and the rod-shaped main shaft and wire claws of the hanger conduit material are coated separately using the electric wire coating method, and then assembled into the hanger. .

Another method involves concentrating an aqueous dispersion of a fluororesin obtained by emulsion polymerization, immersing the metal in the fluororesin desversion, which is a stabilized solution using a nonionic activator, raising the dust, and firing. Moshike commercially available enamel,
For example, Polyflon enamel manufactured by Daikin Industries, Ltd. (trade name) is applied to the hanger rib, dried, and then fired.

In any case, the orange layer J(
(A thickness of about 200μ is sufficient.

Of course, the hanger must be able to conduct electrolytic current to the item to be plated, so the part of the hanger body that comes into contact with the power supply bar, and one of the hanger's claws. If the fluorine cat fat coating is not applied only to the part to which the article is attached, or if it has been coated once,
That part must be mechanically removed to expose the metal conduit and processed in a way that does not impede electrical conduction.

In the invention, once an article is attached using the above-mentioned fluororesin-coated hanger, the article is plated with metal by an electrolytic method without being removed from the hanger, and is then plated with an anion. Only after completion of the electrodeposition coating and baking process is the article removed as a finished product, the hanger is recycled for use in securing newly plated articles.

However, when using anionic water-based paints, the water-based paints used will not adhere to the surface of the hanger. Fluororesin coatings inherently have excellent electrical insulation properties, so they do not adhere electrically, and their non-adhesive properties prevent them from physically adhering. Moreover, even if it adheres for some reason, it can be easily peeled off and removed. Of course,
Paint is electrodeposited on the parts of the hanger's pipes and nails that are exposed for energization. ÷4 It is simultaneously cured during the baking process, but the cured film can be removed by use of conventional paint strippers.

As such stripping agents, highly alkaline ones containing sodium hydroxide and amines, and solvent-type ones such as methylene chloride are known, but both can be used to easily strip the fluororesin coating. Since the hanger according to the present invention is used, the plating is not affected at all.
This made it possible to cycle through electrodeposition coating, baking, and plating.

The present inventors have developed a hanger (conventional product) whose main body is a copper round bar with a diameter of 7MH and a length of 80077!1, and whose outer surface is coated with ABS H4 fat and has 20 screws fixed with stainless steel of φ2yya as claws. An iron plate of 10 edges x 5 widths was attached to each claw using chrome plating, and then the anionic water-based paint was fixed, and the hanger was replaced and baked. A comparison was made using the hanger according to the present invention coated with Daiflon enamel and not changing the hanging of the article at all during the entire process.
The latter method saves 20 minutes per cycle.

Next, a durability test was conducted on the conventional hanger described above and the hanger according to the present invention. That is, each hanger has 20
After heating at 0°C for 1 hour, the film was heated to 60°C containing 40.0% caustic potassium and 20% methylene chloride as a coating stripping solution.
The test involves immersing the material in an aqueous solution for 2 hours and determining how many cycles it takes for defects to occur, with this operation being considered as one cycle.

As a result, the conventional hanger changed color and melted after 1 cycle, but the hanger according to the present invention showed no abnormality even after 20 cycles.

Therefore, it is clear that the hanger according to the present invention is extremely robust and can withstand being reused dozens of times.

Claims (1)

[Claims] The article to be plated is suspended on a hanger coated with fluororesin, and after electrolytic plating of metal is applied, the plated article thus obtained is subjected to anionic electrodeposition coating without removing it from the hanger. and the article after the painting,
A method for coating an article, characterized in that the article is subjected to a baking treatment without being removed from the hanger.