MERKSTEIJN JACOBUS LAMBERTUS V (NL)
| WO1991018951A1 | 1991-12-12 | |||
| WO1995019399A1 | 1995-07-20 |
| EP0459048A1 | 1991-12-04 |
| 1. | Method for colour composition of a powder lac quer, which method comprises the following successive steps of: combining at least two lacquer powders of mutually differing colour, and subsequently mixing the individual lacquer powders to form a statistically homogeneous mixture. |
| 2. | Powder lacquer for coating a surface using elec trostatic spraying, wherein the powder lacquer is com posed of powder lacquer particles, which powder lacquer particles are mixed in statistically homogeneous manner in at least two mutually differing colours by performing the method as claimed in claim 1. |
| 3. | Lacquer layer manufactured from a powder lacquer as claimed in claim 2 which is electrostatically sprayed and subsequently enamelled into a homogeneous layer, in which homogeneous lacquer layer the colour differences of the original individual powder lacquer particles can still be discerned. |
In powder coating according to a pneumatic method powder lacquer is sprayed through for instance a wire cage at 60-100 kV at the earthed object for spraying. The powder lacquer particles are charged in the electrical field and move in the direction of the field strength gradient to the object. The advantage is that the rear side thereof is also coated and that paint losses are small. It is also possible to guide the powder lacquer to a rotating bell-jar or disc which itself has already been brought to said potential. The part of the powder lacquer which does not deposit on the object, which is generally limited, can be recovered in a separate installation.
The powder lacquer is commercially obtainable in a number of standard colours, and for differing colours there has to be consultation with the supplier of the powder lacquer who can then develop a new powder lacquer in the desired colour.
The present invention has for its object to increase the possibilities of applying colour variations in powder lacquers and lacquer layers to be manufactured therewith.
The invention also has for its object to provide a simple method for colour composition of the powder lac- quer.
The invention provides for this purpose a method for colour composition of a powder lacquer, which method comprises the following successive steps of: -combining at least two lacquer powders of mutually differing colour, and
-subsequently mixing the individual lacquer powders to form a statistically homogeneous mixture.
The invention also provides a powder lacquer for coating a surface using electrostatic spraying, wherein the powder lacquer is composed of powder lacquer parti- cles, which powder lacquer particles are mixed in statis- tically homogeneous manner in at least two mutually differing colours by performing the above specified method according to the invention.
Finally, the invention also provides a lacquer layer manufactured using such a powder lacquer, in which lac- quer layer the colour differences of the original indi- vidual powder lacquer particles can still be discerned.
By mixing together powder lacquers of varying co- lours a mixed colour results, the colour of which depends on the colours of the starting powder lacquers as well as on the ratios in which they are mixed. Experimental mixtures have thus been manufactured from powder lacquers in the basic colours yellow, green and red in the respec- tive ratios 1: 1: 1,2: 1: 1,1: 2: 1 and 1: 1: 2. These four different mixtures were then sprayed electrostatically onto test plates which were finally enamelled. The final result consisted of four homogeneous lacquer layers of varying colours. From a distance, i. e. more than half a metre, the lacquer layer has an even appearance. From a short distance, i. e. less than a distance of half a metre, the"pixels"of the original powder lacquer parti- cles are visible. Since these powder lacquer particles are fused to a homogeneous layer, the appearance of the lacquer layer from a short distance can be compared to a TV screen or a half-tone colour photo. In particular applications this appearance can provide precisely the desired aesthetic effect, while in other applications, for instance in industrial constructions, it is not in any way conspicuous and the lacquer layer appears to be completely homogeneous.
An important advantage of this manner of colour composition of a powder lacquer is that colour variants can be manufactured, for instance for individual clients, without consultation with a supplier of the powder lac-
quer. Another advantage is that in this way remnants of powder lacquer can be processed into a lacquer layer with a colour which is deemed less important.
The present invention will be further elucidated with reference to the following figure. The figure shows a top view of an enlarged part of a lacquer layer 1 according to the invention. The lacquer layer 1 is built up of powder lacquer particles which have fused into the homogeneous lacquer layer 1 by enamelling. The homoge- neous lacquer layer 1 is built up of small areas 2,3,4 which each result from a melted powder lacquer layer particle. The colours of the respective areas 2,3, 4 of lacquer layer 1 are different because the powder lacquer particles from which areas 2,3,4 are created had differ- ent colours. Areas 2,3,4 are thus fused together to form a homogeneous lacquer layer 1, but from the colour of an area 2,3,4 it is still possible to make out the colour of the powder lacquer granule from which the relevant area 2,3,4 was created. As shown in this figure, lacquer layer 1 is built up of powder lacquer particles of three dif- ferent colours. This can be inferred from the three different hatchings with which the respective areas 2,3,4 are marked.
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