JPS61227874A - Energizing treatment of plastic product in electrostatic coating line - Google Patents

Abstract

PURPOSE:To apply a coating without any uncoated part and unevenness by immersing a material to be coated in the energizing treating liq. in a treating vessel to form an electrically conductive coated film on the surface and hanging the material on a conveyer. CONSTITUTION:When a plastic material to be coated is electrically treated in an electrostatic coating line, a treating vessel 7 filled with an energizing treating liq. 6 obtained by mixing 0.1-0.2% surfactant into methanol, isopropyl alcohol, etc., is provided at the fitting position A in the vicinity of a chain conveyer 1. After the whole surface of the material 3 to be coated is dipped in the energizing treating liq. 6 in the treating vessel 7, the material is hung on a hanger 2. Consequently, since an electrically conductive coated film is uniformly formed on the whole surface of the material 3 to be coated, electricity is surely conducted to the hanger 2 when the material is hung on the hanger 2. Accordingly, a coating without any unevenness can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of energizing plastic objects to be coated in an electrostatic coating line.

Problems to be Solved by the Prior Art and the Invention In general, in an electrostatic coating line, the object to be coated is suspended from a conductive conveyor running approximately horizontally by a conductive hanger and transported to the painting position. By applying a high voltage to the tip of the spray gun installed at the painting position, an electrostatic field is formed between the object to be coated and the spray gun via the hanger, and the atomized paint ejected from the spray gun is attracted by electrostatic attraction. However, if the object to be coated is made of plastic or other non-conductive material, conventionally the object to be coated is coated in advance before being hung on a conveyor. Add a surfactant to a lower alcohol such as methanol or isopropyl alcohol by 0.5 to 1.
By spraying a 0% mixed energization treatment liquid with a spray gun to form a conductive film on the surface, the surface of the object to be coated is grounded via a conveyor, making electrostatic coating possible. However, in this method of forming a conductive film on the surface of an object to be coated by spraying the energizing treatment liquid, the energizing treatment liquid is not sufficiently applied to the back side of the object that comes into contact with the hanger. It is difficult to spray the energizing treatment liquid evenly over the entire surface of the object to be coated.
It is not possible to form a conductive film uniformly over the entire surface, and the conductivity differs in different parts of the surface.As a result, the suction force of the atomized paint differs in each part, resulting in uneven paint application and unpainted parts. There was a simple drawback.

The present invention eliminates these drawbacks and provides a plastic product that can uniformly form a conductive film over the entire surface of the plastic object to be coated in an electrostatic coating line. The purpose of the present invention is to provide a method for energization processing in an electrostatic coating line.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an electrically conductive chain conveyor that runs horizontally toward the left in the figure, and this chain conveyor 1 has a number of electrically conductive hangers 2.
are hung at equal intervals, and the plastic workpieces 3 suspended from these hangers 2 at position A are sequentially conveyed to painting position B.

A high voltage generator applies a DC high voltage between the spray gun 5 provided at the coating position B and the chain conveyor 1, and the spray gun 5 side is maintained at a negative high potential with respect to the grounded chain conveyor 1. ing.

Near the chain conveyor 1, which is installed at position iA, there is a treatment tank 7 filled with an energized treatment liquid 6 made of a lower alcohol such as methanol or isopropyl alcohol mixed with 0.1 to 0.2% surfactant. It is installed and the object to be painted 3
The substrate is energized by being immersed in the energizing treatment liquid 6 in the treatment tank 7 so that its entire surface is immersed, and then hung on the hanger 2.

The object to be painted 3 that has been subjected to the energization treatment in this way is =3
- Since a conductive film is uniformly formed on its entire surface, when it is hung on the hanger 2, electricity is reliably connected to the hanger 2. When this object 3 to be coated is conveyed to the front of the spray gun 5 by the chain conveyor 1, its entire surface and the spray gun 5
An electrostatic field is formed between the spray gun 5 and the negatively charged atomized paint, which flies along the uniformly formed electrostatic field over the entire surface of the object 3 to be painted. Thing 3
The coating is applied evenly to the entire surface, leaving no spots or uneven coating.

Structure and Effects of the Invention As specifically explained in the above embodiments, the method of energizing in an electrostatic coating line for plastic products according to the present invention is based on the method of applying electricity in an electrostatic coating line for plastic products, in which a plastic object to be coated is mounted on a conveyor that runs in one direction. and the object to be coated is electrically conductive and transported to the painting position, and the spray gun provided at the painting position and the conveyor are connected to a high voltage generator to connect the spray gun and the object to be painted transported to the painting position. In an electrostatic coating line for plastic products, an electrostatic field is formed in the spray gun, and the atomized paint sprayed from the spray gun is guided to the object to be coated by the electrostatic field and applied to the surface of the object. The object to be coated is immersed in an energized treatment liquid in the processing tank to form a conductive film on its surface, and then mounted on the conveyor.

Since the object to be coated is immersed in the energizing treatment liquid filled in the treatment tank, a conductive film is uniformly formed over the entire surface of the object, ensuring that electricity is supplied to the charge supply contacts of conveyors, etc. At the same time, the entire surface is grounded, and as a result, the atomized paint ejected from the spray gun is attracted to the entire surface and is evenly applied to the entire surface, resulting in the effect that the paint can be applied without any unpainted areas or uneven coating.

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining one embodiment of the present invention. 1: Chain conveyor 3: Object to be painted 5 Varnish spray gun 6: Electrifying treatment liquid 7: Treatment tank B: Painting position

Claims (1)

[Claims] The plastic object to be painted is mounted on a conveyor that runs in one direction, and is electrically connected and transported to the painting position.
The spray gun provided at the coating position and the conveyor are connected to a high voltage generator to form an electrostatic field between the spray gun and the object to be coated conveyed to the coating position, and the mist ejected from the spray gun is In an electrostatic coating line for plastic products, in which the chemical paint is guided to the object to be painted by the electrostatic field and applied to the surface of the object, a processing tank containing an energized treatment liquid is installed, and the object to be painted is A method for energization treatment in an electrostatic coating line for plastic products, characterized by immersing the product in an energization treatment liquid in the treatment tank to form a conductive film on its surface, and then mounting the product on the conveyor.