JPS58270A - Electrostatic painting method - Google Patents

Abstract

PURPOSE:To make uniform painting in fine patterns possible by applying light to the surface of a conductive base material while applying the electric charge of the chargeability reverse from that of a photoconductive material and applying the same electric charge as that of the photoconductive material then coating a non-conductive material electrostatically thereon. CONSTITUTION:Photosensitive resin paint is applied for a mask on the prescribed surface of a conductive base material 1 and is dried, after which a necessary pattern 3 is put on a photosensitive resin paint film 2 and is subjected to an exposure treatment. This is developed to form a prescribed pattern 2', on which paint dispersed with a photoconductive material (e.g., CdS) is coated. After the coating layer 5 is dried, the pattern 2' is stripped to leave only the layer 5. The CdS charges electrostatically to - when irradiated with light and therefore, with the material 1 as a positive electrode and a painting gun 6 as a negative electrode, light is applied to this and a voltage is applied, thence a non- conductive material 7 such as perfluoroalkoxy resin or the like is electrostatically painted on the material 1. After the material 1 deposited with the material 7 is baked, the layer 5 is removed with toluene or the like, whereby only the desired pattern 7 is allowed to remain.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic coating method, and more particularly to a method for forming a non-conductive substance in an arbitrary fine pattern on a conductive substrate surface.

Electrostatic coating is attracting attention from the viewpoint of resource saving and improvement of environmental hygiene as it does not use solvents.

Also, because it is easy to form a coating layer with a uniform thickness, it can be applied to large surfaces such as chairs, rust, refrigerators, etc. It is used for full-scale exterior applications such as the body.

As described above, the electrostatic coating method has superior features compared to all solvent coating methods, but it has been considered unsuitable for small surfaces to be coated or for fine patterns (for example, display symbols).

On the other hand, as a method for obtaining a coated surface with a fine pattern, a method is known in which a photosensitive or radiation-sensitive resin layer is provided and patterning is performed by selectively exposing or irradiating the resin and developing it.
In this method, the applicable resin is limited to those having photosensitivity or radiation sensitivity, and it is not possible to use any resin such as Par7aa alkoxy resin.

The present invention was made in response to this problem, and by making improvements to the surface to be coated, the conventional electrostatic device remains unchanged.
The present invention aims to provide an electrostatic coating method that can uniformly and thickly coat any non-conductive substance in a fine pattern on the surface of a conductive substrate.

In other words, the present invention selectively! A step of applying a photoconductive substance onto the surface of the conductive substrate that has been dried, and applying a charge opposite to the chargeability of the photoconductive substance to the surface of the conductive substrate while irradiating the photoconductive substance with light. A step of electrostatically coating a nonconductive substance by applying a charge equal to the chargeability of the conductive substance, and applying the nonconductive substance deposited on the conductive substrate surface by the electrostatic coating to the conductive substrate. This is an electrostatic coating method characterized by having a step of baking onto the surface.

An embodiment of the present invention will be described below based on the drawings. First, aluminum 1, whose surface has been appropriately polished and degreased, will be used as a conductive base material.
Prepare a aluminum plate◎ Next, place it on the specified surface of this aluminum plate 1! Apply photosensitive resin paint to the fabric. (FIG. 1) Here, the photosensitive resin coating may be a commercially available one, such as an aqueous solution in which a weight pA ammonium monoxide is dissolved in an aqueous polyvinyl alcohol solution.

After that, it is dried, and the photosensitive resin coating film 2 is covered with a necessary pattern 3 and exposed to light. Reference numeral 4 indicates a light source lamp (Fig. 2) After selectively curing the photosensitive resin coating 2 through this exposure, a development process is performed to dissolve and remove the uncured photosensitive resin layer to form the predetermined pattern 2. (FIG. 3) After the above patterning, the aluminum plate 1 is coated with a polyester paint in which cadmium sulfide (hereinafter abbreviated as Od8), which is a photoconductive substance, is dispersed. (FIG. 4) After this coating H5 is dried, the cured photosensitive resin pattern 2' is peeled off. In this case, it can be easily peeled off by boiling it in an aqueous sodium chloride solution, leaving only the coating layer 5 of the O40 polyester paint on the aluminum plate 1. (Fig. 5) O40 is negatively charged when irradiated with light, so the aluminum plate 1 to be painted is the positive electrode, and the coating gun 6 is the negative electrode.
A voltage of about 0 to 100 kV is applied to electrostatically coat the exposed surface of the aluminum plate 1 with Par 7aa alkoxy resin (manufactured by Mitsui 70 Rochemical Co., Ltd., MP-10) 7. (FIG. 6) At this time, 650 light spectrally divided light is irradiated. Light that is not spectrally divided may also be used. In addition to O40, photoconductive substances that are negatively charged include zinc oxide, polyvinylcarbazole, etc., and photoconductive substances that are positively charged include, for example, selenium. When using a press-loading device, the voltage applied is negative to the aluminum plate and positive to the electrostatic coating gun.

Next, the aluminum plate 1 coated with the Par70 tetraalkoxy resin T is baked at 310 to 400 DEG C. for about 10 to 60 minutes. (FIG. 7) The polyester layer 5 containing @Od8 is removed with toluene. Only the pattern T made of the desired par-70 alkoxy resin remains on one surface of the Al (z lam board. (Fig. 8)) In the above, an example was shown in which an aluminum plate was used as the conductive base material. In addition to the aluminum plate, other conductive metal plates as well as those in which a conductive foil or film is integrally disposed on a heat-resistant insulating substrate can also be used.

Further, although the above example shows that masking is performed using a photosensitive resin, it is also possible to use a so-called radiation-emitting resin whose molecules are cross-linked and hardened or disintegrated to have a lower molecular weight when irradiated with an electron beam. Also, if fine bars are not required, they may be masked with paper or the like.

As described above, according to the present invention, a desired fine pattern can be easily formed on the surface of a conductive substrate using a non-photosensitive, non-radiation sensitive synthetic resin such as Per70 tetraalkoxy resin. In other words, there is no wastage of resources due to solvent volatilization, and there is no negative impact on hygiene, and the coating can be applied arbitrarily, even if the object is ugly or in a narrow area. Moreover, since the coating layer formed in the above-mentioned arbitrary pattern is baked onto the base material, it is difficult to separate, has good abrasion resistance, and maintains and exhibits its function as a coating layer semi-permanently.

[Brief explanation of drawings]

1 to 8wJ are cross-sectional views showing embodiment examples for explaining the steps of the method of the present invention. 1-''--Aluminum plate 2--Unit photosensitive resin coating 2'--Photosensitive resin pattern 5-111 Photoconductive material coating layer 7 --------Par 70 pipe alkoxy resin Fig. 1 Fig. 3 Fig. 2'! Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. g

Claims (1)

[Claims] 1. Be selective! A step of applying a photoconductive substance onto the surface of the conductive substrate that has been dried, and applying a charge opposite to the chargeability of the photoconductive substance to the surface of the conductive substrate while irradiating the photoconductive substance with light. A step of electrostatically coating a non-conductive substance by applying a charge equal to the chargeability of the conductive substance, and applying a conductive substance deposited on the surface of the conductive substrate by the electrostatic coating to the conductive substance. An electrostatic coating method characterized by comprising a step of baking onto a surface.