Reflective coating

Abstract

Compositions containing diamond particles for producing reflective coatings and methods of wet and dry application of diamond particles to substrates to produce reflective coatings. The coatings have a desirable appearance, are robust and easy to apply.

Claims

1. A liquid composition comprising: visible, reflective diamond particles, wherein substantially all of the diamond particles have a largest dimension in the range of 35-175 μm; and a binder which is transparent when the liquid composition dries to form a solid coating, wherein the liquid composition is used for producing the solid coating, wherein said diamond particles are visible and reflective in the solid coating.

2. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 35-100 μm.

3. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 50-175 μm.

4. The liquid composition according to claim 1, wherein the particle size ranges are obtained by sieving.

5. The liquid composition according to claim 1, wherein the diamond particles are natural diamond particles.

6. The liquid composition according to claim 1, wherein the ratio between the mass of the diamond particles and the mass of the binder is between 5:100 and 15:100.

7. The liquid composition according to claim 1, wherein the binder is transparent.

8. A method of producing a reflective coating, comprising the steps of: (i) applying liquid composition of claim 1 to a substrate; and (ii) causing or allowing the composition to dry to form an initial reflective coating.

9. The method according claim 8, wherein the method further comprises the step of: (iii) applying a further said liquid composition over the initial reflective coating, wherein substantially all of the diamond particles in the further composition applied in step (iii) have a largest dimension which is smaller than the largest dimension of substantially all of the diamond particles in the initial reflective coating.

10. The method according to claim 8, wherein the method further comprises the step of: (iii) applying a further said liquid composition over the initial reflective coating, wherein substantially all of the diamond particles in the further composition applied in step (iii) have a largest dimension which is larger than the largest dimension of substantially all of the diamond particles in the initial reflective coating.

11. The method according to claim 8, wherein the method further comprises the step of applying a protective layer over the initial reflective coating.

12. The method according to claim 11, wherein the substrate is transparent and wherein the protective layer is opaque.

13. The method according to claim 11, wherein the substrate is opaque, and wherein the protective layer is transparent.

14. The method according to claim 8, wherein the substrate is glass.

15. The method according to claim 8, wherein the diamond particles have a morphology consistent with having been obtained by crushing larger particles.

16. The method according to claim 8, wherein the diamond particles are natural diamond particles.

17. The method according to claim 8, wherein the composition is applied so that 20-40 g of diamond particles are present in the reflective coating per square meter of substrate.

18. The method according to claim 8, wherein the composition is applied so that 25-30 g of diamond particles are present in the reflective coating per square meter of substrate.

19. An article comprising a dried liquid composition according to claim 1.

20. The article according to claim 19, wherein the article is an item of furniture, or a vehicle, or a wearable item, or an architectural feature.

21. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 35-55 μm.

22. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 37-44 μm.

23. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 44-53 μm.

24. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 100-175 μm.

25. The liquid composition according to claim 1, wherein substantially all of the diamond particles have a largest dimension in the range of 145-175 μm.

26. The liquid composition according to claim 1, wherein the diamond particles are natural diamond particles and have a morphology consistent with having been obtained by crushing larger particles.

27. The liquid composition according to claim 1, wherein the ratio between the mass of the diamond particles and the mass of the binder is between 7:100 and 10:100.

28. The liquid composition according to claim 1, wherein the binder is clear coat.

Description

(1) Embodiments of the invention will now be described, with reference to the figures of the drawings, in which;

(2) FIG. 1 shows a coated substrate according to the invention.

(3) FIG. 2 shows a magnified view of a coated substrate shown in FIG. 1.

(4) FIG. 3 shows the coated substrates of examples 2, 4, 5, 6 and 7 according to the invention.

(5) FIGS. 4 and 5 show further views of the coated substrate of example 7 according to the invention.

(6) FIG. 6 shows coated substrate of example 6 according to the invention.

(7) FIG. 7 shows a coating according to the invention produced using the composition of example 8.

(8) FIGS. 8, 10 and 11 show a coating according to the invention produced using the composition of example 9.

(9) FIG. 9 shows a coating according to the invention produced using the composition of example 10.

(10) FIGS. 12-16 show coatings according examples 11-14 of the invention.

(11) In the Examples below the diamond particle sizes quoted are in respect of the largest (maximum) dimension of each particle.

EXAMPLE 1

(12) Diamond flakes were acquired. They were of mixed sizes and from natural cleaved diamonds.

(13) The flakes obtained ranged from powder of a few microns to approximately 2.0 mm flakes. They were not sorted into sizes. The flakes were sieved to obtain substantially only particles having a maximum dimension of less than 1.15 mm. This was done because the largest airbrush nozzle which was available was 1.20 mm in diameter. Larger flakes would have clogged the nozzle.

(14) A gloss varnish was then applied to the substrate. A Flakebuster® airbrush (available from TCP Global Corp) was used to apply the diamond flakes to a surface instead of suspending the flakes in a paint. That is to say, the application was dry flakes onto a wet binder (varnish). Diamond particles were sprayed onto the still wet surface of the varnish using compressed air. A pressure of 3 bar was used.

(15) Consequently the flakes stuck into the wet varnish. Any flakes sprayed outside of the wet varnish were simply brushed together and re-used again. Using a Flakebuster® also means that flakes larger than 1.20 mm could also have been used. With a Flakebuster® one can apply flakes up to 3 mm in size.

(16) In the initial sample some of the flakes where very thin but exceeded the diameter of 1.20 mm. They resembled small disks which would reflect the light well.

(17) A base coat of wicked platinum was applied to a substrate prior to application of the varnish or flakes then a gloss varnish was applied over the base coat. Approximately 4 layers of the diamond flakes (having a maximum diameter of less than 1.15 mm) were sprayed onto the gloss varnish using the Flakebuster® whilst the gloss varnish was still wet/tacky.

(18) A small strip of the coated substrate was coated with ‘candy blue’, a transparent blue varnish, at 50%. The strip and the rest of the coated substrate was then coated with 30 layers of clear coat (two component version) to cover the flakes completely and obtain a smooth surface.

(19) The surface was then sanded with silicon carbide water-proof 3000 and finally buffed with a micro fibre cloth and polishing paste.

(20) The results are shown in FIGS. 1 and 2. FIG. 1 shows the coated substrate and its blue strip portion. FIG. 2 shows the coated substrate (non-blue strip portion) at 10× magnification.

(21) The coated surfaces have an appealing finish which is also robust and quick to apply.

EXAMPLES 2-7

Wet, and Alternatively, Dry Application

(22) Five compositions having diamond particles with different ranges of maximum dimensions were prepared as follows. Diamond powders formed from crushed natural diamonds were obtained to provide diamond particles. The desired particle size ranges were obtained using the sieving method discussed below in relation to the ‘glass substrate’ examples. Size ranges refer to the maximum dimension of the particles in question. Other methods of size selection are however available.

(23) The application was either wet or dry (as detailed in the examples below) to professional display models measuring 21×12×5 cm i.e. approximately 1:20 times the size of a car. Wet application was done with the diamond particles premixed in a clear coat and sprayed onto the surface. Dry application was done generally as described above in the preliminary tests.

(24) Additional layers of clear coat where applied in order to guarantee a smooth surface.

EXAMPLE 2

(25) Blue model (with trademark): 53-105 μm diamond particles, approximately 0.3 g/1.5 ct, mixed in clear coat (i.e. wet application).

EXAMPLE 3

(26) Black model: 44-53 μm diamond particles, approximately 1 gram/5 ct, dry application on half the model.

EXAMPLE 4

(27) Pearl white model: 149-177 μm diamond particles, approximately 0.1 gr/0.5 ct, mixed in clear coat (i.e. wet application) and a second layer with 105-149 μm, approximately 0.2 gr/1 ct, mixed in clear coat (i.e. wet application).

EXAMPLE 5

(28) Orange model: 37-44 μm diamond particles, approximately ½ gram/2.5 ct, dry application.

EXAMPLE 6

(29) Green model: 37-44 μm diamond particles, approximately 1.5 gram/7.5 ct, dry application.

EXAMPLE 7

(30) A half/half model was made to show the difference between the black base coat paint and the diamond containing composition (as described in example 3 above).

(31) The results are shown in FIGS. 3-6. The overall visual effect of these coatings is very appealing. It was found to be easier to apply greater volumes of diamond on the surface using dry application. The black background seems to provide the best effect. The distinction between the diamond containing composition and the paint is striking.

(32) When applying diamond containing compositions as a liquid, it was found that one should not use flakes having a maximum dimension larger than 105 μm in order to guarantee a smooth surface. This is particularly useful in automobile applications.

EXAMPLES 8-10

Glass Substrate

(33) A composition containing diamond particles was applied to sheets of glass in order to test the visual effect of the diamond containing composition for use in the finishing of luxury goods, for example interiors.

(34) Compositions containing three different size ranges of (crushed) natural diamond particles were prepared. Diamond particles of the required size ranges were obtained using two sieving steps. The first sieving step removed particles which have a maximum dimension which is larger than a desired upper limit. The second sieving step removed smaller particles which fall through the second sieve. The particles retained on the second sieve have a minimum dimension which is larger than the apertures in the second sieve. It is the particles retained on the second sieve which have maximum diameters within the desired size ranges. It was these particles that were used in the compositions. However, other methods for obtaining desired size distributions are available, not least (given the high value of the product) selecting appropriate diamond crystals by hand, optionally with the aid of a microscope.

(35) The compositions prepared contained differing proportions of diamond particles and binder.

EXAMPLE 8

(36) Diamond particle size: 53-105 μm,

(37) 5 g of diamond particles in 100 g of clear coat.

EXAMPLE 9

(38) Diamond particle size: 105-149 μm,

(39) 7 g of diamond particles in 100 g of clear coat.

EXAMPLE 10

(40) Diamond particle size: 149-172 μm,

(41) 10 g in 100 g of clear coat.

(42) To produce each composition diamond particles having the appropriate sizes were thoroughly mixed in the appropriate proportions into clear coat. In each of the examples 8, 9 and 10 the composition was applied using a Flakebuster® airbrush (available from TCP Global Corp) to a primed glass surface. Application was done twice, crossways. The glass was then sealed with an opaque black lacquer which was applied over the clear coat containing the diamond particles.

(43) FIG. 7 shows the coating produced using the composition of example 8. FIGS. 8, 10 and 11 show the coating produced using the composition of example 9. FIG. 9 shows the coating produced using the composition of example 10.

(44) All of the coatings produced are visually appealing. Mixing the particles with the clear coat resulted in the heavier particles dropping to the bottom of the clear coat quite quickly which made application more difficult. The compositions were therefore constantly agitated during application. Because of this there was a low distribution on the glass surface of the larger flakes.

(45) It is preferable to apply approximately 300 g of each composition per square meter. This equates to approximately 25 to 30 g of diamond particles (125 to 150 ct) per square meter to obtain an appealing finish.

EXAMPLES 11-14

Automobile Applications

(46) The following components were applied to a substrate using conventional spraying techniques:

(47) 1. An undercoat/base primer coat,

(48) 2. Top colour coats (of a number of different colours were used depending on the depending on the example), and

(49) 3. Two top coats of a resin-based layer containing 150 to 200 μm crushed natural diamond particles. The coating was applied so that no diamond points were sticking out above the coating. The top coats also contained metallic/metal flakes and glass beads.

(50) Example 11 was based on a silver undercoat. Example 12 was based on a pearl undercoat. Example 13 was based on a blue undercoat. Example 14 was based upon a black undercoat.

(51) The top coats may be a range of resin based finishes comprising polyester, melamine, acrylic and alkyd melamine. For automobile applications the paint system usually comprises the 1-pack primer for polypropylene and acrylic substrates and a resin based top-coat of polyurethane, nitrocellulose, acrylic, cab acrylic and polyester.

(52) Metal flakes and glass flakes for use in paints are commercially available. Their application is described in U.S. Pat. No. 3,228,897, the contents of which are hereby incorporated by reference. In the present invention however, there appears to be synergy between the metal and glass flakes and the diamond particles. This is shown by the particularly appealing finish in FIGS. 11-16.

(53) It has also been found that including glass particles renders the coatings more robust. This is particularly useful for automobile applications where protection against the elements is required. The metal and glass flakes in the composition also help the coating to stand up to temperature tests from minus 38° C. to +40° C., which is particularly useful in automobile applications.

(54) Summary—The invention provides diamond particle-containing compositions for producing reflective coatings and methods of wet and dry application of diamond particles to substrates to produce reflective coatings. The coatings have a desirable appearance, are robust and easy to apply.