Electrolysis: processes – compositions used therein – and methods – Product produced by electrolysis involving electrolytic...
Reexamination Certificate
1999-08-06
2002-05-28
Bell, Bruce F. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Product produced by electrolysis involving electrolytic...
C204S471000, C204S499000, C204S504000, C204S505000, C204S506000
Reexamination Certificate
active
06395162
ABSTRACT:
The present invention relates to a car body coating process in which a shell body is formed using plastics-covered metal plates to a portion or whole of the shell body of a car body and the exposed metal portion of the shell body is coated by electrodeposition.
In a car body of a normal or small passenger car, the portion constituted mainly with sheet metal without riggings such as engine or chassis is called shell body which is constituted usually with a main body consisting of underbody, side member, roof, cowl, upper back, lower back etc. and outer cover parts such as hood, front balance, front fender, cowl louver, door, luggage (back door) etc.
Up to the present, in order to form these main body and outer cover parts, metal plate is cut and molded in the size and form of each constituting part and the parts are assembled to a shell body which is dipped into an electrodeposition paint bath to form a primer film on the surface, backside, edge surface portion etc. by electrodeposition coating. Intermediate paint, topcoat paint etc. are then coated to these outer portions.
Recently, however, operation step saving, energy saving and CO
2
reduction in the coating line is strongly desired also in the coating of a car body. Moreover, further improvement in throwing power of electrodeposition paint to edge surface portion, chipping resistance of the total coating film, corrosion resistance etc.
In the coating of a car body, on the other hand, there is proposed an inverse method (for example, Japanese Patent Publication No. 41317/1980), in which a substrate is powder-coated and the uncoated portion is coated by electrodeposition, for the purpose of the reduction of solvent discharge and improvement of edge surface coatability of electrodeposition paint. This method has, however, such problems as that powder coating facilities become additionally necessary, and that the corrosion resistance of the boundary portion between powder coating film and electrodeposition coating film is not sufficient.
The present inventors have repeatedly conducted studies to solve the above-mentioned problems in the coating of a car body. As a result, this time, they found that the above-mentioned problems can be solved by one effect by forming a shell body by using a metal plate covered with plastics layer, which has been prepared previously, to a portion or whole of the shell body of a car body, and coating the exposed metal portion in the shell body by electrodeposition.
Thus, according to the present invention there is provided a car body coating process characterized by forming a shell body using a plastics-covered metal plate to the main outer parts of a car body, and then coating the exposed metal portion in the shell body by electrodeposition (this process is hereinafter referred to as Process I).
According to the present invention there is provided also a car body coating process characterized by forming a shell body equipping car parts, which have been made by cutting, molding and joining a plastics-covered metal plate for the main outer portions of a car body, to a previously assembled main body of a car body, and then coating the exposed metal portion in the shell body by electrodeposition (this process is hereinafter referred to as Process II).
Then, the car body coating process of the present invention is described in more detail.
The process of the present invention can be applied mainly to normal and small passenger car, but can be also applied to truck, bus, motorcycle, vehicle with special kind of equipment car etc. in the same manner.
As a metal plate to be covered with plastics, metals, which have been used for a car body up to the present, can be similarly used. As the material, there may be mentioned, for example, iron, steel, stainless steel, aluminum, copper, and alloys containing these metals, and further plate of these metals whose surface is plated with zinc, zinc
ickel, iron etc. They can be used usually in coils or processed in cut plates. The thickness of these metal plates is suitably in the range of generally 0.3-2.0 mm, particularly 0.5-1.0 mm and the surface of these metal plates is preferable to be treated suitably by grinding, degreasing, with phosphate etc. in order to improve the adhesivity with a plastics layer, corrosion resistance etc.
As plastics materials to cover the above-mentioned metal plates, there can be used per se known thermoplastic resins, for example, polyolefin resin such as polyethylene, polypropylene etc., polyester resin such as polyethylene terephthalate (PET) etc., polycarbonate resin, epoxy resin, vinyl acetate resin, vinyl chloride resin, fluorine-containing resin, polyvinyl acetal resin, polyvinyl alcohol resin, polyamide resin, polystyrene resin, acrylic resin, polyurethane resin, phenolic resin, polyether resin, cellulose type resin etc. They may contain color pigment, extender pigment etc.
Covering of a metal plate with these plastics materials can be performed by per se known methods including, for example, sticking onto the metal plate plastics in film or sheet formed by the methods such as extrusion molding, injection molding, calender molding, compression molding etc.; sticking with pressure onto the metal plate molten plastics extruded in film or sheet; adhering plastics in powder form onto the metal plate by the methods such as fluidized immersion, electrostatic coating etc. and then melting by heating. Particularly the process of sticking plastics in film or sheet onto the metal plate is preferable. Covering of a metal plate with plastics is performed at least to the surface of a metal plate located at outer side of a car body. However, it is possible to cover both surfaces, if desired. The thickness of the plastics layer covering a metal plate is preferable in the range of usually 1-100 &mgr;m, particularly 3-75 &mgr;m, more particularly 5-50 &mgr;m. Moreover, it is possible to treat the surface of these plastics by corona discharge, plasma, flame etc. before or after the covering onto the metal plate.
On covering a metal plate with plastics, in case of sticking plastics in film or sheet onto the metal plate, it is preferable to previously coat an adhesive to the metal plate and/or plastics film or sheet, in order to increase adhesivity between the two. As such an adhesive there may be mentioned thermosetting or thermoplastic adhesives containing one or more kinds of resins selected from, for example, bisphenol type epoxy resin, resol type epoxy resin, acrylic resin, aminoplast resin, polyester resin, urethane resin, polysiloxane resin etc., and further containing optionally a curing agent. Further, there can be used as adhesive triazinethiol type compounds such as 2,4, 6-trimercapto-S-triazine, 2-dibutylamino-4, 6-dimercapto-S-triazine, 2,4,6-trimercapto-S-triazine-monosodium salt, 2,4,6-trimer-capto-S-triazine-trisodium salt etc.
In the Process I according to the present invention, a shell body is assembled by cutting, molding and joining the plastics-covered metal plates, which have been prepared as mentioned above. Specifically each part of the main body and outer cover parts is prepared using the plastics-covered metal plate, and then the parts are assembled to form a shell body.
Shell body is a portion in a car body, constituted mainly with sheet metal without riggings such as engine or chassis. Its main body is constituted mainly with parts such as underbody, side member, roof, cowl, upper back, lower back etc. and the outer cover parts consists mainly of parts such as hood, front balance, front fender, cowl louver, door, luggage (back door) etc. Parts of outer cover parts are called car parts.
Underbody here means the floor portion of the cabin, trunk room etc. and is named generically, including front underbody, front floor, rear floor etc. Side member forms the side of a cabin joining with a front body, roof panel, underbody etc. and prevents the car from bending and/or twisting. Cowl is a panel combining left, right, front and rear pillars. Upper back is a panel combining left and right quarter panels (rear fender) at t
Hiraki Tadayoshi
Tominaga Akira
Watanabe Tadashi
Yawata Takeshi
Bell Bruce F.
Kansai Paint Co. Ltd.
Nicolas Wesley A.
Wenderoth Lind & Ponack LLP
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