Coating processes – Frictional application
Reexamination Certificate
1999-03-19
2001-02-13
Parker, Fred J. (Department: 1762)
Coating processes
Frictional application
C427S262000, C427S263000, C427S280000, C427S281000, C427S365000
Reexamination Certificate
active
06187371
ABSTRACT:
TECHNICAL FIELD
This invention relates to the continuous application of liquid or semi-liquid paint coatings to a moving substrate.
The invention was devised primarily for the application of coatings of paint to metal strip, for example steel strip coated with a corrosion resistant metallic alloy, and is described primarily in that context hereinafter. However it will be apparent that it is applicable to the application of paint coatings to substrates of other materials, provided the substrate is substantially impervious to the coating and, at least in preferred embodiments of the invention, is capable of being heated to above the glass transition temperature of a solid paint composition to be applied to the substrate.
BACKGROUND ART
The application of paint to steel strip in large scale, continuously operating, steel finishing mills is a highly developed art.
Typically, the substrate strip is progressed through a coating station wherein liquid paint, comprising pigments and other paint solids dissolved in a solvent or otherwise dispersed in a liquid carrier, is applied to the substrate by a dipping, spraying, roller coating or like process for applying a liquid film to the substrate, which film is subsequently allowed or caused to evaporate to leave a solid paint coat on the substrate.
It is also known to apply paint composition to a heated substrate wherein the paint is applied as a liquid melted from a solid body of substantially solvent free paint composition by contact of the body with, or near approach of the body to, the hot substrate. In this context the term “liquid” includes high viscosity liquids, that may approach soft, plastic solids in nature, as well as easily flowing liquids.
That last mentioned mode of depositing liquid material on a substrate is referred to as “melt deposition” and the deposited liquid is referred to as a “melt deposit” hereinafter.
Previously the deposition rate of melt deposits was determined by controlling the contact pressure between the solid paint body and the substrate, while maintaining constant all of the many other parameters affecting the deposition rate. Such a process is described in U.S. Pat. No. 3,630,802 to Dettling.
The difficulty of accurately controlling all of those parameters makes it difficult to obtain constant deposition rates of low value when using Dettling type pressure controlled melt deposition processes. This lead to their replacement, in painting operations, by the melt deposition technique described in our Australian patent No. 667716.
Briefly stated, that Australian patent discloses depositing a polymer based coating composition onto a side of a substrate metal strip moving at a constant speed, by heating the strip to a temperature above the glass transition temperature of the composition, and driving a solid block of the composition towards the strip at a predetermined block speed.
It is then only necessary to control the block speed to cause a melt deposit to be applied to the strip at a precisely controlled deposition rate, without the need to closely control other operating parameters, in that each of those other parameters need only lie within a broad range of working values.
As is also disclosed in that Australian patent, the melt deposit may then be spread over the surface of the strip by a pressure roll to emerge as a smooth, wet coating on the strip.
Irrespective of the mode of deposition, the prior art has been restricted to the production of mono-chrome product, wherein a uniform coating is applied to the whole of at least one side of the substrate strip.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide ornamental, plural colour paint coatings, wherein the differently coloured components of the coating are applied during a single pass of a substrate through a painting station.
It is well known that some patterns displaying random variation, in the sense that no repeating module of the pattern may be discerned, may, nevertheless, be seen as being members of a family of related patterns, in the sense that individual expressions of the randomly variable patterns of one family have a recognisable family similarity, enabling them to be readily distinguished, by eye, from individual expressions of the randomly variable patterns of other families.
Wood grain patterns may be cited as typical examples of patterns of the kind referred to in the preceding paragraph. One has no difficulty in distinguishing between veneers of, for example the four “families” of leak, pine, mahogany, and silky oak, although no two pieces of veneer of any one timber are identical.
Such randomly variable patterns maintaining a family resemblance are referred to as “familial, non-modular patterns” hereinafter.
The concept of familial, non-modular patterns is of significance to the present invention. If, for example, a domestic appliance has a cabinet made of panels of plural coloured, painted sheet steel, it is desirable that there be no discernible repetition of the pattern in any one panel or from panel to panel of the appliance, but it is also desirable that each panel bears a strong family resemblance to the others.
Thus, another object of the present invention is to provide for the continuous application of a paint coat displaying a familial, non-modular, colour pattern to a substrate, during a single pass of the substrate through a painting station.
Still another object is to provide for the reproducibility of the family likeness of familial coatings produced by painting operations that may be spaced apart in time.
Meeting that last objective enables a steel finisher, for example, to accept orders for painted strip identified by reference to a familial, non-modular coating illustrated in a catalogue, in the knowledge that he may produce new product that may never display an exact reproduction of the catalogue illustration, but which will nevertheless be regarded by the purchaser as an acceptable expression of the catalogue illustration.
The present invention is based on the experimentally determined discovery that if two or more differently coloured paints are applied as discontinuous, randomly patchy deposits to a stationary target area of a moving substrate, or respectively to stationary target areas that are aligned in the direction of travel of a substrate, then, provided the long term deposition rates, in terms of the volume of the deposit per unit area of the substrate surface that is to be painted, is appropriately chosen and closely controlled, those deposits may be spread and smoothed to form a continuous coat of desired thickness covering a larger area of the substrate surface and displaying a familial, non-modular striated pattern. Surprisingly, even if the paints are similar in composition and are readily miscible, it has been found that the respective colours remain visible as distinct colours in the continuous coat.
Furthermore, the experiments leading to the present invention have shown that if the individual long term deposition rates of the component deposits and the positioning of the target area or areas for each component deposit are reproduced from one operation to another, then the non-modular pattern resulting from each operation will display an unchanging family resemblance. On the other hand, if any one or more of those deposition parameters is changed, the resultant continuous coat will be discerned as belonging to another family.
As of now, the particular family characteristics of any selection of those parameters cannot be readily forecast in advance, and it is necessary to trial any particular selection to determine whether it will produce a pleasing result. However experiments have conclusively demonstrated that the family character of any selection will be reproduced by the same selection on each different occasion.
Therefore, the invention consists in a method of continuously producing a continuous paint coat of substantially constant, pre-determined thickness, and displaying a plural colour, familial, non-modular pattern, on a surface of a moving substrate, comprisi
Davies Mark John
Horton Trevor James
BHP Steel (JLA) Pty. Ltd.
Crockford Kirsten A.
Kerins John C.
Miles & Stockbridge P.C.
Parker Fred J.
LandOfFree
Production of familial, non-modular, plural color patterns... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Production of familial, non-modular, plural color patterns..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Production of familial, non-modular, plural color patterns... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2592502