JPH024475A - Electrostatic coating of nonconductive article to be coated - Google Patents

Abstract

PURPOSE:To raise the effect of attachment of coating material and save coating costs by enabling an electrostatic coating by spraying conductive primer on a nonconductive article to be coated and by bringing both ends of an aluminum tape as earthing wire into surface contact with the article to be secured thereto by application of an adhesive tape. CONSTITUTION:A conductive primer 4a in which conductive substances are suspended is applied to a nonconductive article 4 to be coated by spray coating to decrease surface resistance, thus enabling application of electrostatic coating. And as an earthing wire 6 for an article 4, an aluminum tape 6a with specified width is used, whereby each of the opposite ends thereof are brought into surface contact with a part of the surface of article 4 where surface resistance becomes lower or that of a hanger 3 to be secured by applying adhesive tapes 6 thereto. As a result, contact resistance can be lowered and effect of attachment of coating material in electrostatic coating can be raised, and since the coating material has the same potential as that of the article 4, the coating material can be easily attached to the article in application of electrostatic coating. Since a part of the repeatedly used hanger 3 in contact with the aluminum tape 16a is completely covered by an adhesive tape, cleaning is not required when the hanger is used again.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for electrostatic coating of non-conductive objects.

Conventional technology As a method of painting automobile parts such as bumpers, liquid paint particles are charged with a high-voltage power source and sprayed onto a grounded object.
An electrostatic coating method that prevents paint particles from escaping to areas other than the object to be coated using an electrical attraction effect is generally used (for example, see page 334 of Steel Processing Methods edited by Japan Iron and Steel Institute). When trying to electrostatically coat resin parts such as polypropylene bumpers, which have recently become widely used to reduce weight or streamline manufacturing, the polypropylene bumpers are an electrical insulator. Therefore, the electrostatic coating effect cannot be obtained as it is because the electric attraction effect due to static electricity as described above does not work, so it is necessary to impart conductivity to the surface of the polypropylene bumper, which is the object to be coated, and to impart this conductivity. It is necessary to ensure that the object to be coated is grounded.

The present invention aims to address the above-mentioned problems.

Means for Solving the Problems The present invention provides a method in which paint is atomized using compressed air or electricity, is charged with a high-voltage power source, and is sprayed onto a workpiece supported by a hanger. In an electrostatic coating method designed to improve adsorption efficiency, when the object to be coated is non-conductive, the object to be coated is sprayed with a conductive primer in which a predetermined amount of conductive substance powder is suspended. Using an aluminum tape of a predetermined width as a ground wire to reduce the surface resistance value and electrically connect the hanger to the surface of the object to be coated having the reduced surface resistance value,
It is characterized in that the aluminum tape is adhered and fixed from above with an adhesive tape so as to completely cover the surface of the object to be coated and the surface contact portion with the hanger.

Function By imparting conductivity to the primer used as an undercoat for coating, it is possible to reduce the surface resistance of non-conductive objects to be coated at a small cost, making electrostatic coating possible. An aluminum tape of a predetermined width is used as the ground wire, and both ends of the aluminum tape are brought into surface contact with a portion of the surface of the object to be coated where the surface resistance value has decreased and the hanger, and the contact resistance is fixed by pasting and fixing that portion with adhesive tape. It is possible to improve the coating efficiency of paint during electrostatic painting by lowering the potential, and because it is at the same potential as the object to be coated, paint easily adheres during electrostatic painting. Since the hanger is completely covered with the adhesive tape, it is possible to prevent the paint from going around to the surface contacting portion, making it unnecessary to clean the surface contacting portion when the hanger is reused.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, l is a rail arranged on the floor, 2 is a trolley that moves at a predetermined speed on the rail 1 by a power source (not shown), and 3 is placed on the trolley 2 to support the object to be coated 4. In the secondary hanger, a ground wire 5 is connected between the cart 2 and the secondary hanger 3 and between the secondary hanger 3 and the workpiece 4.
and 6 are provided, and the ground wires 5 and 6 atomize the paint fed into an atomizing head (not shown) by the action of compressed air or electricity, and charge it with a high voltage power source.
It forms the ground return path for the electrostatic coating equipment that attaches to the surface.

In the above, when the object 4 to be coated is an electrical insulator such as a polypropylene resin pad made by injection molding of polypropylene resin, the coating is continuously applied from the surface part of the object 4 to be coated to the ground wire attachment part. It is necessary to provide electrical conductivity and to electrically reliably connect the ground wire attachment portion provided with electrical conductivity to the ground wire 6.

Therefore, in the present invention, as a method of imparting conductivity to the object to be coated 4, which is an electrical insulator, a conductive primer 4a in which a predetermined amount of metal powder, for example, aluminum powder is suspended, is applied to the object to be coated 4 as shown in FIG. A method is adopted in which air spray painting is carried out continuously from the surface area to be coated to the ground wire attachment part, and as shown in FIG. The joint portion of the aluminum tape 6a with the secondary hanger 3 or the object to be coated 4 is made of adhesive having adhesiveness only on the back side so that the end of the aluminum tape 6a is in surface contact over a predetermined length, for example, about 20 mm. tape 6b
It is designed to be pasted by covering it over the top.

Even if the conductive primer 4a spray-coated on the surface of the object 4 as described above has a relatively high resistance to the surface current flowing on the surface, the conductive primer 4a and the aluminum tape 6a used as the ground wire 6 are Because they are in contact, the contact resistance value can be reduced, and as a result, the coating efficiency of the paint due to electrostatic effect can be greatly improved, for example from 23% to 52%, reducing paint costs. The surface contact area of the secondary hanger 3 with the aluminum tape 6a, which is at the same potential as the object and which is easily adhered to during electrostatic painting and is used repeatedly, is completely covered with the adhesive tape 6b. It is possible to prevent the paint from going around and eliminate the need to clean the surface contact portion when the secondary hanger 3 is reused.

Furthermore, when the method of the present invention is applied to a wet-on-wet painting method in which the top coat is repeatedly applied while the intermediate coat is still wet, the aluminum tape can be pasted and fixed as a ground wire only once. It has the advantage of

Effects of the Invention As described above, according to the present invention, a conductive primer in which a predetermined amount of conductive substance powder is suspended is applied to a non-conductive object by spraying to reduce the surface resistance value, thereby reducing the non-conductive material. In addition to making electrostatic coating possible on the object to be coated, an aluminum tape of a predetermined width is used to connect the ground wire of the object to be coated, and both ends of the aluminum tape are connected to the areas where the surface resistance value of the surface of the object to be coated has decreased and By making surface contact with the hanger and fixing that part with adhesive tape, it is possible to reduce contact resistance, improve the coating effect of electrostatic coating, and reduce paint costs. Because of this, paint tends to adhere during electrostatic painting, and the surface contact area of the hanger that is used for recording and reprinting with the aluminum tape is completely covered with adhesive tape, preventing paint from going around to the surface contact area. This can bring about many practical effects, such as making it unnecessary to clean the surface contact portion when the hanger is reused.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention. FIG. 2 is a perspective view showing the state of adhesion between an aluminum tape and an adhesive tape. l...rail, 2...bogie, 3...secondary hanger,
4...Object to be coated, 4a...Conductive primer, 5.6...
・Ground wire, 6a...Aluminum tape, 6b...
·Adhesive tape. Figure 1 and above

Claims (1)

[Claims] Electrostatic painting in which paint is atomized by compressed air or electricity, charged by a high-voltage power source, and sprayed onto the object supported by a hanger to improve the efficiency of adsorption of paint particles to the object through electric suction. In the method, when the object to be coated is non-conductive, a conductive primer in which a predetermined amount of powder of a conductive substance is suspended is spray-painted on the object to reduce the surface resistance value, and the reduced surface resistance value is reduced. An aluminum tape of a predetermined width is used as a ground wire to electrically connect the surface of the object to be coated, which has a surface resistance value, and the above-mentioned hanger, and the aluminum tape completely covers the surface of the object to be coated and the surface contact portion with the hanger. An electrostatic coating method for non-conductive coating materials, which is characterized in that it is fixed from the top with adhesive tape.