Coating processes – Applying superposed diverse coating or coating a coated base – Synthetic resin coating
Patent
1997-02-06
1998-07-28
Cameron, Erma
Coating processes
Applying superposed diverse coating or coating a coated base
Synthetic resin coating
524591, 525127, 525131, 525440, 525454, 525460, B05D 136
Patent
active
057860335
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF APPLICATION
This invention concerns a method of forming multi-layer paint films, base coat compositions and a method of painting and, more precisely, it concerns a method of forming multi-layer paint films with which a good finished appearance can be obtained, aqueous base coat compositions which have excellent storage stability and with which paint films which have a good finished appearance can be obtained, and a method of painting therewith.
PRIOR ART
In general, a series of paints are painted onto the base when painting automobiles. The first coat is an electrodeposited primer and, after this, a mid-coat paint is painted on and then the base coat for the overcoat paint is painted on over this and finally a clear coat is painted on as a top coat. The base coat is the one which imparts good decoration to the final finish by means of a organic pigment or inorganic pigment, and a metallic finish is desirable for the finish of many automobiles. A metallic pigment, such as aluminium flakes for example, is generally compounded in the base coat in order to obtain the metallic effect.
Paint film formation of the base coat and the clear coat (top coat) is normally achieved by wet-on-wet painting, which is to say that the clear coat is painted on without baking after painting on the base coat and then flashing off (drying) for a short period of time at room temperature, and subsequently baking and drying the base coat and clear coat at the same time.
Large amounts of organic solvent are included in the paints, and especially the base coat paints, for automobile purposes which are on the market at the present time. However, concern over the volatile organic solvents which are released into the atmosphere is increasing, and much effort is being directed towards the research and development of aqueous paints which contain water in the main as the solvent and in which the amount of organic solvent is small.
The orientation of the metallic pigment flakes in the paint film contributes to the metallic effect. Hence, in order to obtain a metallic effect with a base coat, the metal pigment flakes which are present in the base coat must be orientated appropriately after painting. They have to be immobilized immediately, and care must be taken to ensure that they are not disturbed in the next process, namely clear coat painting.
Difficult problems arise as a result of the physical properties of water when developing water based paints which have a metallic effect. At the present time, compositions which can be used as water based base coats are limited from the viewpoint of orientation as mentioned above. Water based paints which have a metallic effect have been disclosed, for example, in European Patents EP-A-89497, EP-A-355433 and EP-A-521919, German Patents DE-OS-3545618, DE-OS-3903804 and DE-OS-4107136, and U.S. Pat. No. 4,719,132.
The use of base coats in which silica thickeners which have thixotropic properties are compounded in multi-layer film formation is disclosed in the abovementioned patents, and painting with a view to providing beauty and protection is carried out by forming a base coat/clear coat type multi-layer film on the base material using base coats of this type.
However, with base coats which contain silica such as those indicated above, the storage stability of the paint at high temperature is poor and there is a difficulty in that a good paint film finished appearance cannot be obtained.
Furthermore, an aqueous paint composition wherein an aqueous polyurethane resin and various silica based thickeners are combined has been disclosed in the abovementioned European Patent EP-A-89497. However, in this patent there is no indication at all as to the type of silica based thickener which is used, or the electrical conductivity of the thickener.
Furthermore, the combination of sodium magnesium silicate and acrylic copolymer based thickener and/or other synthetic resin based thickener and/or auxiliary thickener (associative thickener) has been disclosed in German Patent DE-A-4110520, b
REFERENCES:
patent: 4489135 (1984-12-01), Drexler et al.
patent: 4719132 (1988-01-01), Porter, Jr.
Gast Achim
Shiomi Kazuki
Taniguchi Hitoshi
BASF Lacke & Farben AG
Cameron Erma
LandOfFree
Method of forming multi-layer paint films, base coat composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of forming multi-layer paint films, base coat composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of forming multi-layer paint films, base coat composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-21413