PVD METAL EFFECT PIGMENT POWDER

Abstract

The invention relates to powder made of coated PVD metal effect pigment, highly concentrated suspensions of coated PVD metal effect pigment as well as the use thereof in powder lacquers and masterbatches. The powder according to the invention made of coated PVD metal effect pigments is characterized by a very good redispersibility and is outstandingly suitable in particular for the preparation of highly concentrated suspensions. Furthermore, it is very free flowing, substantially agglomerate-free and results in coatings with excellent metallic gloss.

Claims

1-20. (canceled)

21. A powder made of a coated PVD metal effect pigment, wherein the coated PVD metal effect pigment comprises a PVD metal effect pigment and a metal oxide layer, wherein the metal oxide layer amounts to 5 to 45 wt.-%, based on the total weight of the coated PVD metal effect pigment.

22. The powder according to claim 21, characterized in that the metal oxide layer comprises silicon dioxide, aluminium oxide, titanium dioxide, iron oxide, tin oxide, zinc oxide or mixtures thereof, and/or wherein the metal oxide layer was applied wet chemically.

23. The powder according to claim 21, wherein the metal oxide layer amounts to 30 to 44 wt.-%, based on the total weight of the coated PVD effect pigment.

24. The powder according to claim 21, characterized in that a bifunctional or monofunctional organic compound comprising a silane is bound to the metal oxide layer.

25. The powder according to claim 21, wherein the metal effect pigment comprises a metal made of aluminium, titanium, chromium, zirconium, copper, zinc, gold, silver, tin, steel, iron as well as alloys thereof and/or mixtures thereof.

26. The powder according to claim 21, wherein the metal effect pigment comprises a metal made of aluminium, titanium, chromium, zirconium, copper, zinc, gold, silver, tin as well as alloys thereof and/or mixtures thereof, and/or wherein the BET surface area of the coated PVD metal effect pigment is between 15 and 90 m.sup.2/g.

27. The powder according to claim 21, wherein the PVD metal effect pigment is an aluminium effect pigment coated with an SiO.sub.2 layer, wherein the SiO.sub.2 layer amounts to 5 to 45 wt.-% of the total weight of the coated PVD metal effect pigment.

28. A powder lacquer comprising the powder according to claim 21.

29. A suspension comprising a coated PVD metal effect pigment suspended in a solvent, wherein the coated PVD metal effect pigment comprises a PVD metal effect pigment and a metal oxide layer, wherein the metal oxide layer amounts to 5 to 45 wt.-%, based on the total weight of the coated PVD metal effect pigment, characterized in that the suspension comprises 70 wt.-% or more of the coated PVD metal effect pigment.

30. The suspension according to claim 29, characterized in that a weight percent of the coated PVD metal effect pigment in the suspension is 75 wt.-% or more, and/or the solvent is a medical white oil.

31. The suspension according to claim 29, wherein the PVD metal effect pigment is an aluminium effect pigment coated with an SiO.sub.2 layer, wherein the SiO.sub.2 layer amounts to 5 to 45 wt.-% of the total weight of the coated PVD metal effect pigment.

32. A masterbatch comprising solid granules formed from a composition comprising: a PVD metal effect pigment, a coating of a metal oxide layer provided to the PVD metal effect pigment, wherein the metal oxide layer amounts to 5 to 45 wt.-%, based on a total weight of the coated PVD metal effect pigment, and a plastic.

33. The masterbatch according to claim 32, wherein the plastic is selected from polypropylene, polyamide and polycarbonate.

34. A process for producing a PVD metal effect pigment powder, comprising the steps of: a) coating metal effect pigments produced by PVD processes with metal oxide in a sol-gel process, wherein the metal oxide layer amounts to 5 to 45 wt.-%, based on the total weight of the coated PVD metal effect pigments, b) solid-liquid separation of the coated metal effect pigments from the reaction mixture, c) drying the coated metal effect pigments obtained at 100° C. to 140° C., wherein a powder is obtained.

35. The process according to claim 34, wherein the PVD metal effect pigment is an aluminium effect pigment and the metal oxide layer is an SiO.sub.2 layer, wherein the SiO.sub.2 layer amounts to 5 to 45 wt.-%, preferably 30 to 44 wt.-%, based on the total weight of the coated PVD metal effect pigment.

36. The process according to claim 34, wherein the drying in step c) is performed in a rotary kiln at 120° C.

Description

REFERENCE EXAMPLE 1

[0060] 200 g Decomet 1002/10 (with 10% solids content) from Schlenk Metallic Pigments GmbH is suspended in 400 g isopropanol. 47 g tetraethoxysilane is added to this mixture and this mixture is heated to 60° C. Then, 100 g water followed by 6 g ammonia are added and the mixture is stirred for a further 4 h. The mixture is then filtered off via a glass frit. The filter cake obtained is then adjusted to 10% with isopropanol. The metal oxide layer amounts to 40 wt.-%, based on the total weight of the coated PVD metal effect pigment.

EXAMPLE 2

[0061] 200 g Decomet 1002/10 from Schlenk Metallic Pigments GmbH is suspended in 400 g isopropanol. 47 g tetraethoxysilane is added to this mixture and this mixture is heated to 60° C. Then, 100 g water followed immediately by 6 g ammonia are added and the mixture is stirred for a further 4 h. The mixture is then filtered off via a glass frit. The filter cake obtained is then dried in a drying kiln at 120° C. for 12 h. The metal oxide layer amounts to 40 wt.-%, based on the total weight of the coated PVD metal effect pigment.

EXAMPLE 3

[0062] 200 g Decomet 1002/10 from Schlenk Metallic Pigments GmbH is suspended in 400 g isopropanol. 47 g tetraethoxysilane is added to this mixture and this mixture is heated to 60° C. Then, 100 g water followed immediately by 6 g ammonia are added and the mixture is stirred for a further 4 h. The mixture is then filtered off via a glass frit. The filter cake obtained is then dried in a drying kiln at 120° C. for 12 h. The metal oxide layer amounts to 40 wt.-%, based on the total weight of the coated PVD metal effect pigment.

[0063] Then, pasting takes place in a Speedmixer with Ondina oil to form an 80% suspension (this highly concentrated suspension can also be referred to as paste).

[0064] The obtained powders, highly concentrated suspensions and low-concentration slurries were then examined.

Instructions for Spreading the Obtained Powders/Suspensions from Examples 2 and 3:

[0065] 0.2 g of the dried powder is placed in a 25 ml plastic beaker with 1.8 g isopropanol. To this dispersion is added 3 g of the binder medium A (a nitrocellulose-based lacquer). The mixture is dispersed in a Speedmixer (device: DAC 250 SP) with a rotational speed (1000 rpm for 10 s; 2000 rpm for 15 s; 2500 rpm for 30 s; 2000 rpm for 10 s; 1000 rpm for 5 s), mixed through briefly once again with a spatula and then spread on the substrate on a coated paper with a 24 μm spiral blade. The spreading dries after five minutes at room temperature and can then be measured with a reflectometer (Tri-Gloss from Byk-Gardner). The agglomerate formation is determined visually.

Instructions for Spreading the 10% Slurry from Reference Example 1:

[0066] To 2 g of the slurry (10%) is added 3 g of the binder medium A. The mixture is dispersed in a Speedmixer (device: DAC 250 SP) with a rotational speed (1000 rpm for 10 s; 2000 rpm for 15 s; 2500 rpm for 30 s; 2000 rpm for 10 s; 1000 rpm for 5 s), mixed through briefly once again with a spatula and then spread on the substrate on a coated paper with a 24 μm spiral blade. The spreading dries after five minutes at room temperature and can then be measured with a reflectometer (Tri-Gloss from Byk-Gardner). The agglomerate formation is determined visually.

Instructions Bulk Weight:

[0067] By measuring the weight of a predetermined volume of aluminium powder, the bulk weight or the bulk density of an aluminium powder is determined with the units g/ml or g/cm3.

[0068] A measuring cylinder made of brass (contents 50 ml) is placed on the scales and tared to 0. A sufficient quantity of aluminium powder is placed on an ounce paper (Pergamyn Echo, 35 g/m.sup.2, unbleached, glazed) and carefully loosened crosswise (3×) using a spatula. The powder is now introduced slowly into the metal cylinder, which is standing on a paper, skimmed with a metal sheet and weighed.

[0069] The assessment takes place using the following equation:

[00001]$\frac{\mathrm{Original}.Math..Math.\mathrm{sample}.Math..Math.\mathrm{weight}.Math.\left[g\right]}{50.Math..Math.\mathrm{ml}.Math..Math.\mathrm{volume}}=\mathrm{Bulk}.Math..Math.\mathrm{weight}.Math.\left[g.Math.\text{/}.Math.\mathrm{ml}\right]$

[0070] The following test results were obtained.

Comparison of Gloss, Bulk Weight

[0071]

TABLE-US-00001 Gloss 60° Bulk weight Ref. Ex. 1 109.8 — Ex. 2 95.3 0.0384 Ex. 3 93.5 —

Comparison of Particle Size Distribution

[0072]

TABLE-US-00002 D10 D50 D90 span Ref. Ex. 1 6.06 μm 13.35 μm 22.75 μm 1.25 Ex. 2 6.58 μm 14.77 μm 26.66 μm 1.36 Ex. 3 6.21 μm 13.50 μm 23.18 μm 1.26

[0073] A comparison of the gloss values shows that on drying the 40% coated material according to the invention (Examples 2 and 3), only a small deviation in gloss occurs in comparison with the reference material from reference example 1. In the case of only small coating quantities below 5 wt.-%, it had been shown that on drying the material, a significant decrease in the gloss occurs compared with the undried material. This shows that the 40% coated material substantially retains the optical properties of the starting material, while on drying a less than 5% material, a significant decrease in the gloss occurs compared with the undried material. The coated and dried material according to the invention is furthermore convincing with its narrow particle size distribution and good redispersibility. From the PSD values it can be seen that no substantial increase in particle size occurs even after a 40% coating with SiO.sub.2.

[0074] With the present invention it is therefore possible to obtain the advantages of powder forms and highly concentrated suspensions, wherein the good optical properties of such pigments are substantially retained.

[0075] As already observed above, because of the very large surface area of a PVD compared with a conventional pigment, the production of a PVD powder or a PVD paste is a major challenge. In the following table, the specific surface areas of a highly concentrated PVD powder compared with pigment powders of conventional silver dollar and cornflake pigments are represented to make this clearer.

TABLE-US-00003 BET surface Pigment area (m.sup.2/g) Powdal ® 3200 (silver dollar) 1.17 Powdal ® 3400 (silver dollar) 1.57 Powdal ® 2900 (cornflake) 10.9 Decomet SiO2 (from Ex. 2) 24.4