JPH05140798A - Electrodeposition coating method - Google Patents

Abstract

PURPOSE:To prevent the electrodeposition of paint on a jig and to eliminate the need to release a coating film by covering at least the part to be dipped of the jig for suspending a material to be coated in electrodeposition coating in an electrodeposition paint bath with a pressure-sensitive conductive material. CONSTITUTION:A material to be coated is dipped in an electrodeposition paint bath, a DC voltage is impressed between the material and a counter electrode to form a coating film, the material is pulled up, the coating film is washed with water, and the film is baked. In these processes, the material is suspended from a conveyor and supported by a hooked jig (made of steel or stainless steel). The part of the jig to be dipped in the bath is covered with a pressure- sensitive conductive material (conductive rubber sheet, etc., having <=50OMEGA.cm electric resistance at 2500g/cm<2> pressure). Consequently, the paint is not deposited on the jig, and the accumulated coating film need not be released periodically.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION The present invention relates to an electrodeposition coating method using a jig coated with a pressure sensitive conductive material.

In electrodeposition coating, an article to be coated is dipped in a bath for electrodeposition coating, a DC voltage is applied between the article to be coated and a counter electrode to form an electrodeposition coating film, and then the article to be coated is pulled up. Then wash the coating with water,
It is done by baking. During these steps, the article to be coated is suspended and supported on the conveyor by a hook-shaped jig, and power is supplied to the article to be coated in the paint bath through this jig. This jig (hereinafter referred to as hanger) is usually made of steel or stainless steel, and the hook portion for hooking the article to be coated has a sharp blade shape to ensure electrical contact with the article to be coated. However, since the paint is electrodeposited and baked on the part of the hanger that is immersed in the paint bath as well as the object to be coated,
The coating film accumulates during repeated use of the hanger,
Eventually, the electric current between the hanger and the object to be coated becomes poor, so it is necessary to periodically remove the accumulated coating film. The peeling of the coating film is a method of mechanically removing by grinding, a method of removing by burning,
There are methods such as chemical removal using a release agent,
Both of them are time-consuming and time-consuming, and a large number of spare hangers must be prepared for use during maintenance work.

For this reason, a sawtooth-shaped or screw-shaped contact portion with the object to be coated, and a heat-treated and strengthened blade shape having a trade name of liverless hanger have been devised and used. There is no change in that the coating must be peeled off at some point only by extending the period that can be used without.

Therefore, the present invention provides an electrodeposition coating method which requires no maintenance of the hanger and can be used substantially semipermanently.

According to the disclosure the present invention [0005] The present invention, to form a該被coating object surface to electrodeposition coating by applying a DC voltage between the article to be coated and the counter electrode in the electrodeposition coating bath,
Next, in the electrodeposition coating method, which comprises pulling up the object to be coated and baking the formed electrodeposition coating film, at least a jig for suspending and supporting the object to be coated and supplying power thereto during the electrodeposition and baking process. Provided is a method for electrodeposition coating, which comprises coating a portion to be immersed in an electrodeposition coating bath with a pressure-sensitive conductive material for use.

Since the pressure-sensitive conductive material becomes conductive only in a portion to which pressure is applied, an electric current flows only through a portion in contact with an object to be coated of a hanger covered with the material and supporting its own weight, and the like. Since no current flows in the part, the paint is not electrodeposited on the hanger itself. Therefore, the hanger can be repeatedly used substantially semi-permanently without maintenance.

The hanger is formed by coating a required portion of a main body made of a conductive material such as steel, aluminum, copper, stainless steel, titanium, zinc and various alloys with a pressure sensitive conductive material. The shape is arbitrary, but it is preferable that the portion in contact with the object to be coated has a blade shape so that the load is concentrated on a small area.

The pressure-sensitive conductive material is, for example, CS made by Yokohama Rubber.
It is commercially available as a 57-7RSC conductive rubber sheet or the like. The coating may be formed by wrapping and fixing such a conductive rubber sheet around the hanger body, or by vulcanizing and pressing the material around the body. The material is 50 at a load of at least 2500 g / cm ^2.
It has been found that it should exhibit a resistance value of Ω · cm or less, preferably 10 Ω · cm or less.

The present invention is applicable to both anion electrodeposition and cation electrodeposition, and the object to be coated is a cathode in the case of cation electrodeposition, an anode in the case of anion electrodeposition, and a hanger. It can be carried out by a usual method except that the above is used.

EXAMPLE As a hanger, a copper body wound with a conductive rubber sheet CS57-7RSC made of Yokohama Rubber and a body not covered with a conductive rubber sheet were prepared, and a test piece was suspended on these hangers to obtain a commercially available cation battery. It is immersed in a coating material (Power Top U-30 manufactured by Nippon Paint Co., Ltd.), the object to be coated is the cathode, and the stainless steel beaker containing the coating material is the anode. In the case of a hanger, a DC voltage of 180 V is 3
Apply for minutes, then pull up the object to be coated, rinse with tap water,
It was baked at 175 ° C. for 20 minutes. The film thickness and appearance of the obtained cured coating film were as follows.

Uncoated hanger Coated hanger ───────── ───────── Electrodeposition condition 180V × 3 minutes 200V × 3 minutes Membrane pressure 20μ 18μ Good coating appearance Good

Although the formation of an electrodeposition coating film was observed on the uncoated hanger, no coating film was formed on the coating hanger.

Claims (2)

[Claims] 1. An electrodeposition coating film is formed on the surface of an object to be coated by applying a DC voltage between the object to be coated and a counter electrode in an electrodeposition coating bath, and then the object to be coated is pulled up. In an electrodeposition coating method comprising baking an electrodeposition coating film, at least a portion of a jig for suspending and supporting an object to be coated during the electrodeposition and baking process and supplying power to it is immersed in the electrodeposition coating bath. A method for electrodeposition coating, which comprises coating with a pressure-sensitive conductive material for use. 2. The method according to claim 1, wherein the electric resistance of the pressure-sensitive conductive material is 50 Ω · cm or less under a pressure of at least 2500 g / cm ² .