JPS629198B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a double-coated article, in which an electrocoated layer is laminated on an electroplated layer, and particularly to a method for continuous production thereof. By applying a coating on top of metal-plated items, you can prevent the metal plating layer from being oxidized in the air or corrode by harmful gases, or use a light-colored and transparent paint. By use,
The appearance of the article can be improved. When applying such coatings, if the surface shape of the article to be coated is relatively simple and has few irregularities, a relatively uniform coating film can be obtained by spray painting or depth coating, but it is not possible to obtain a relatively uniform coating film by spray painting or depth painting. Products with complex surface irregularities, such as plated products, tend to sag or fog, making it impossible to obtain a uniform coating, which often impairs the original characteristics of a plated product. The ideal coating for plated products allows the formation of a thin coating that does not impair the metallic feel and is transparent and does not give the impression of being painted, and the thickness of the coating can be easily controlled. , is an electrodeposition coating using water-based paint that has a uniform coating thickness. Therefore, one possible process is to perform electrolytic plating and then perform electrodeposition coating with a water-based paint. As is well known, in the electrolytic process, the article to be plated is suspended in an aqueous solution containing a predetermined metal salt, which is an electrolytic bath, while the article is attached to a fixing jig, and electricity is applied to the article surface. A plating layer of a predetermined thickness is formed. In addition, in the electrodeposition coating process, the article to be coated is suspended on a hanging jig and charged to (+).
The article is passed through an aqueous paint bath that is electrically charged (-), thereby causing the paint to be electrically attracted to the surface of the article. Next, the article with the paint adsorbed in the form of a film is directly transferred to the baking process, where it is heated at 170 to 220℃.
The coating undergoes a curing process that takes approximately 30 minutes. Through this treatment, the polymeric substance that is the vehicle for the water-based paint undergoes thermal polymerization and/or crosslinking reactions, forming a strong coating film, thus completing the surface coating of the article. As you can see from the process described above, if you want to carry out this process in the most efficient and rational way,
The object of the present invention is to use a common jig for attaching articles in the electrolytic plating process and a hanging jig in the electrodeposition coating process. In this way, the article after it has been sent out from the plating process can be washed with water if necessary without being removed from the plating jig, subjected to electrodeposition coating as it is, and then subjected to the coating film curing treatment. You should be able to get the advantage of being able to make people comply. However, such a combination of processes is actually unknown. This is because the jig for attaching objects used in the electrolytic plating process usually uses copper as the aggregate.
A claw for attaching an article made of stainless steel wire or piano wire is soldered to this, and the parts other than the claw, which serve as a contact point, are covered with thermoplastic resin. This resin coating is an indispensable condition for reducing the power required for electrolytic plating and increasing efficiency. However, the thermoplastic resin used for the coating has a heat resistance temperature of only 140 to 170°C at most. Therefore, if the nail is subjected to heat curing treatment after electrodeposition coating while it is attached to such a attachment jig, the coating on the jig will of course melt during the treatment, and the nails will be damaged. The solder that welds them will also melt. If such a thermoplastic coating were to be replaced with another type of heat-resistant material, the excellent throwing power, which is a feature of the water-based electrodeposition coating, would be a problem, and the jig would be damaged. Since the contacts are also covered with a coating film, which acts as an insulating film, there is a risk that current will not be generated in the next electrolytic plating process and plating will not be possible. Moreover, since the coating film baked by the heat curing process has excellent chemical and solvent resistance, it is difficult to peel it off easily. Therefore, if the article sent out from the electrolytic plating process is to be subjected to electrodeposition coating and heat curing treatment, it is necessary to maintain the attachment jig.
The stock will inevitably increase and become uneconomical. The present invention has been made from this point of view, and as shown in FIG. If necessary, after surface purification 2 such as washing with water, electrodeposition coating 3 of a water-based paint is applied as is, and the surface is removed from the paint bath and sent to a drying process 4.
When the paint film reaches the stage where it is dry to the touch,
The article A2 is removed from the jig B, then subjected to coating film curing treatment 5, and the jig is removed from the other jig.
B' is immersed in an alkaline stripping solution, thereby peeling off the adhesion film of the jig 6, and if necessary, washing with water and drying 7, and then forming a new coated article A.
This is a method for manufacturing an adhered article, characterized in that the adhered article is attached and reused in the electrolytic plating step 1. As mentioned above, the articles delivered from the electrolytic plating process are article A1 attached to jig B, and in this state, the entire surface is cleaned by a normal degreasing process (not shown in the figure). This term refers to an article in which a plated metal film is formed on the surface of the article by subjecting it to electrolytic plating treatment as usual, and is not unique to the present invention. Surface purification such as washing with water is performed as necessary.
Of course, in the present invention, removal of metal salt aqueous solution for electrolysis remaining on the plated surface is carried out while the plate remains attached to the attachment jig. In addition to washing with water, cleaning with an organic cleaning solution such as Trichloride or Freon may be used in combination. This is also known and is not unique to the present invention. The subsequent anionic electrodeposition coating of water-based paints uses an anionic water-soluble or water-dispersible paint and electrolyzes the object to be coated as an anode or a cathode, thereby depositing the solid components of the paint onto the surface of the object. This method involves precipitation as a coating film, which is accompanied by a coating film hardening treatment, which will be described later. The anionic electrodeposition paint that can be used in the present invention is a paint with a solid content of about 5 to 30%, mainly composed of water-soluble or water-dispersible resins with excellent weather resistance and discoloration resistance, and a small amount of dye for coloring. Pigments can be included. Examples of resin types include epoxy resins, acrylic resins, and ester resins. Among the same electrodeposition coating methods, cationic electrodeposition coating is excluded because, due to the nature of the paint used for it, it cannot be peeled off from the jig even when immersed in the alkaline stripping solution according to the present invention. Because you can't. Of course, the anionic electrodeposition coating step 3 in the method of the present invention is also carried out continuously while the article after being plated remains attached to the attachment tool, and the article on which the electrodeposition coating film has been formed is placed in an electrolytic bath. The paint is pulled up from the water-based paint tank and sent to the next step, drying step 4, while being attached to the attachment device. Drying step 4 is performed to remove the article after electrodeposition coating from the attachment jig. Therefore, this drying can be stopped to the extent that it is dry to the touch, that is, the coating film does not become sticky or deform when touched with a finger. Such drying may be carried out in such a way that it can be carried out continuously, for example during passage through a tunnel-type drying chamber, as one step in the overall coating process. Normally, it takes about 2 to 10 minutes at 80° to 120°C to dry to the touch. After this drying is completed, remove the painted and touch-dried article A2 from the attachment jig, and
Then, this is subjected to coating film curing treatment 5. For this reason, for example, if you lay it on a metal shelf, as usual,
The coating film is cured by heat treatment at 160 to 220°C for about 10 to 30 minutes, and product A3 is produced. On the other hand, the attachment jig was removed during the touch drying process.
As with the product, B' has a film of paint that has been dried to the touch-dry stage, so as mentioned above, this is removed in the paint film removal step 6, and then washed with water and/or dried in step 7. Afterwards, it is reused to attach a new article A1 to be painted. What made this series of processes possible was, of course, the fact that the film of anionic electrodeposition paint that had adhered to the attachment jig B in the form of a film and had become dry to the touch was removed by alkaline peeling. This is based on the discovery that it can be easily peeled off by immersion in a liquid. The stripping solution discovered by the present inventors is an alkaline aqueous solution with a pH of 8 to 14 and a temperature of 40 to 90°C. Alkaline components include potassium hydroxide, sodium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, sodium hydroxide, primary to tertiary
grade amines, etc. Peeling is possible at temperatures below 40°C, but in that case the immersion time will be slightly longer. In the range of 40 to 90°C, it will peel off in approximately 3 to 10 minutes. The inventors developed a 15×7× with hole for hanging.
A 0.5cm iron plate was hooked onto each of the hooking claws of the hooking jig, and a film thickness of 10 cm was applied using the conventional electrolytic plating method.
Ni was plated on μ. The jig used was φ20mm,
It is a steel rod with a hook part that hooks onto the energized bar with a length of 800 mm.
Forty piano wire hooks were attached to it by soldering, and the entire jig, except for the claws and hooks, was covered with polypropylene to a thickness of 2 mm. For reference, the electrolysis conditions are as follows. Electrolytic bath composition for nickel plating Nickel sulfate 280g/Nickel chloride 60g/Boric acid 45g/PH 4.2 Current density...3A/dm ² Electrolytic voltage...5V Current application time...17 minutes After the electrolytic plating is completed, A plated item,
While attached to the attachment jig, it was washed with water as usual, and then anionic electrodeposition painting was performed. The type of anionic water-based paint used and the electrodeposition conditions were as follows:
As stated in the table. In addition, the obtained coating film thickness is also listed in the same table.

[Table] After pulling this thing out of each paint bath,
Place in a hot air drying oven at ℃ until dry to the touch.
The time required for drying to the touch has little to do with the type of alkaline remover, but it does have some relationship with the types of paint (a) to (c). That is, as a result of actual measurement, (a) 3 minutes;
(b) 3 minutes, (c) 5 minutes. When dry to the touch is achieved as described above, each object to be coated is removed from the attachment jig, and the object to be coated is subjected to the heating curing process of the coating film in the usual manner, and the jig is removed from the second jig. It was placed in the alkaline stripping solutions (A) to (D) listed in the table. In the table, (E) is neutral distilled water and is a comparative example. Since the liquid temperature was known from other experiments, it was kept at 55°C in all cases, avoiding temperatures below 40°C. Incidentally, the attachment jig was naturally coated with each paint over the entire surface, and was at the stage of being dry to the touch.

[Table] When the liquid is added, the coating film that covers the jig will soon swell, and when it is shaken around in the liquid somewhat dramatically,
This causes the coating film to peel off from the jig body. The peeling force can be expressed by the amount of time (minutes) required to reach such a state. Electrodeposition paints (a) to (c),
The results measured for the combinations of stripping solutions (A) and (D) are listed in Table 3.

[Table] As can be seen from this table, the adhered coating film that has reached the dry-to-touch stage is easily peeled off from the jig in a short time of 3 to 10 minutes, so the jig after peeling can be simply washed with water. It was possible to reuse it again to attach new mating objects. As detailed above, according to the method of the present invention, the dual painting process of metal plating and electrodeposition coating, which was conventionally discontinuous and inefficient, can be made continuous as a series. This greatly contributed to improving production efficiency.

[Brief explanation of the drawing]

The attached FIG. 1 is a process diagram of the method of the present invention. A1...A mating body, A2...A mating body with a paint film that is dry to the touch, B...A jig for attachment, B'...A jig to which a paint film that is at the touch stage is attached, 1... Electrolytic plating process, 2...Surface purification process, 3...Electrodeposition coating process, 4...Drying process, 5...Coating film curing process, 6...
... Paint film peeling process, 7... Jig washing and drying process.

Claims (1)

[Claims] 1 The plated article sent out from the electrolytic plating process is coated with anion electrodeposition without being removed from the attachment jig, and then taken out of the paint bath and sent to the drying process, so that the coating film is dry to the touch. When the drying stage is reached, the article is removed from the attachment jig and then subjected to a coating curing treatment, while the removed jig is immersed in an alkaline stripping solution and cured. A method for manufacturing a coated and glazed article, characterized in that after the adhesive film of the tool is peeled off, it is recycled for the electrolytic plating process.