Automobile body-coating method

Abstract

An automobile body-coating method which comprises optionally subjecting an aluminum material in the automobile body to a surface treatment, followed by subjecting to an oxidizing film treatment, essentially or optionally, respectively and successively forming a curable electrodeposition coating film, a water based chipping primer coating film, an intercoat coating film, and a curable topcoat coating film, or comprises applying a film racing material onto an aluminum material or coating film-coated aluminum material, and comprises forming respective multi-layer coating films onto the steel material in the automobile body respectively.

Description

[0001] (1) Field of the Invention[0002] The present invention relates to a coating method of an automobile body partly or wholly consisting of an aluminum material or an oxidized aluminum material, which method is capable of forming a coating film showing good coating film finished appearance in definition properties, smoothness and the like, and good coating film performances in corrosion resistance, fabrication properties and the like.[0003] The present invention also relates to an automobile body-coating method comprising applying a film facing material onto the surface of an aluminum material or an aluminum-material-coated steel material in an outer plate area and / or an inner plate area-of an automobile body comprising an aluminum material, an aluminum material-coated steel material or an aluminum material and steel material-combined metal material, and capable of forming a coating film showing good coating film finished appearance in definition properties, smoothness and the li...

AI Technical Summary

Benefits of technology

[0229] The second embodiment of the first invention makes it possible to form a multi-layer coating film comprising four-layer structure suitable for coating the automobile body simply, economically, in a power-saving way, safely, stably and continuously, and to form a multi-layer coating film showing good properties in finish appearance and coating film performances.

[0230] In the present invention, application of a strong impact force due to collision of rock salt, gravel and the like onto the surface of a multi-layer coating film comprising the water based chipping primer coating film having the above physical properties, the intercoat coating film and topcoat coating film may result that all or almost all of the impact energy may be absorbed into the water based chipping primer coating film without reaching the electrodeposition coating film underneath, and that both the intercoat coating film and topcoat coating film are subjected to almost no physical damage. That is, the water based chipping primer coating film shows a shock-absorbing function against to the impact force from outside, resulting in making it possible remarkably improve anti-chipping properties, to prevent development of rust and corrosion on the steel material due to chipping, and to solve degradation of the topcoat coating film due to collision with rock salt, gravel and the like.

[0231] The use of the aluminum material having a degree of surface roughness of 0.2 .mu.m or less makes it possible to further improve the finish appearance of the multi-layer coating film comprising tri-layer structure.

[0232] The third embodiment of the first invention makes it possible to form a multi-layer coating film comprising a four-layer structure suitable for coating of the automobile body simply, economically, in a power-saving way, safely, stably and continuously, and to form a multi-layer coating film showing good properties in finish appearance and coating film performances.

[0233] application of a strong impact force due to collision of rock salt, gravel and the like onto the surface of a multi-layer coating film comprising the water based chipping primer coating film having the above physical properties and topcoat coating film may result that all or almost all of the impact energy may be absorbed into the water based chipping primer coating film without reaching the electrodeposition coating film underneath, and that both the intercoat coating film and topcoat coating film are subjected to almost no physical damage, that is, the water based chipping primer coating film shows a shock-absorbing function against to the impact force from outside, resulting in making it possible remarkably improve anti-chipping properties, to prevent development of rust and corrosion on the steel material due to chipping, and to solve degradation of the topcoat coating film due to collision with rock salt, gravel and the like.

[0231] The use of the aluminum material having a degree of surface roughness of 0.2 .mu.m or less makes it possible to further improve the finish appearance of the multi-layer coating film comprising tri-layer structure.

[0237] The second embodiment of the second invention makes it possible to form an intercoat coating film and a topcoat coating film suitable for coating the automobile body simply, economically, in a power-saving way, safely, stably and continuously, and to form an intercoat coating film and a topcoat coating film showing good properties in finished appearance and coating film performances. The use of the oxidized aluminum material having a degree of surface roughness of 0.2 .mu.m or less makes it possible to further improve the finish appearance of the intercoat coating film and topcoat coating film.

[0237] The second embodiment of the second invention makes it possible to form an intercoat coating film and a topcoat coating film suitable for coating the automobile body simply, economically, in a power-saving way, safely, stably and continuously, and to form an intercoat coating film and a topcoat coating film showing good properties in finished appearance and coating film performances. The use of the oxidized aluminum material having a degree of surface roughness of 0.2 .mu.m or less makes it possible to further improve the finish appearance of the intercoat coating film and topcoat coating film.

[0198] In the third invention, the surface treatment subjected to the aluminum material is the same as that described in the first and second invention.

[0240] {circle over (2)} The film facing material having the substrate base material layer is such that on collision of external objects such as rock salt, gravel and the like to the surface of the film, the substrate base material layer absorbs an impact energy from the surface, resulting in making it possible to obtain a coating film showing good properties in durability without any-coating film drawbacks such as cracks, peeling off and the like in spite of hard surface, and making it possible to maintain the film performances for a long period of time;

[0241] {circle over (3)} The film surface formed from a cured resin shows a high hardness, good properties in chemical resistance, pollution resistance, sanding resistance;

[0242] {circle over (4)} Application of the film facing material is easy, and provides good finish appearance without producing drawbacks such as wrinkles and the like;

Problems solved by technology

However, application of the conventional coating method to an automobile body part comprising the aluminum material makes it impossible to form a coating film showing good finished appearance and good coating film performances.

A use of an aluminum material in a part of the automobile body, for example, hood, roof, bonnet and the like, may produce such problems that vibration may produce noises while the automobile is running.

However, the direct coating onto the automobile body produces such problems that a selection of an optimum coating method is troublesome, that a uniform coating film thickness is difficult to obtain, that coating drawbacks due to coating, for example, cissing, spitting, foreign particles and the like, may develop, that the coating composition necessary for coating may be consumed in an excess amount, that safe performances of a working environment for coating and controls of safety and health are difficult, that difficulties of recovering used coating films are undesirable from the standpoint of environmental pollution, that use of the spray coating as usual is unable to provide a wide application in appearance, that finishing is planar and short of steric feeling, and the like.

The above setting or predrying means drying under essentially non-curable conditions when heat-curable.

On the other hand, a Ra less than 0.01 .mu.m may result poor adhesion properties between a cationic electrodeposition coating film and the aluminum material.

When the Tg is higher than 0.degree. C., a finally formed coating film show poor properties in anti-chipping properties, corrosion resistance, physical performances and the like.

On the other hand, when lower than -75.degree. C., a finally formed coating film shows poor properties in water resistance, adhesion properties and the like.

Images