Interference pigments on the basis of perlite flakes

Abstract

The present invention relates to pigments, comprising a plate-like substrate of perlite, and (a) a dielectric material, especially a metal oxide, having a high index of refraction; and/or (a) a metal layer, especially a thin semi-transparent metal layer; a process for their production and their use in paints, ink jet printing, for dyeing textiles, for pigmenting coatings (paints), printing inks, plastics, cosmetics, glazes for ceramics and glass.

Claims

1. An interference pigment comprising at least three alternating layers of high and low refractive index, layered structure comprising: a substrate comprising perlite flakes having a median particle size (d.sub.50) of 15-50 m, a floater content of less than 10 percent by volume, and a blue light brightness greater than 80; a first coating on the substrate having a refractive index >1.65 and comprising; a second coating disposed on the first coating and having a refractive index 1.65; and a third coating disposed on the second coating and having a refractive index >1.65.

2. The pigment of claim 1, wherein the thickness of the first coating is 20 to 350 nm.

3. The pigment of claim 1, wherein the thickness of the second coating is 30 to 600 nm.

4. The pigment of claim 1, wherein the thickness of the third coating is 20 to 350 nm.

5. The pigment of claim 1, wherein the first coating comprises a metal oxide, metal sulfide, or metal oxide mixture.

6. The pigment of claim 1, wherein the first coating comprises TiO.sub.2, Fe.sub.2O.sub.3, TiFe.sub.2O.sub.5, Fe.sub.3O.sub.4, BiOCl, CoO, Co.sub.3O.sub.4, Cr.sub.2O.sub.3, VO.sub.2, V.sub.2O.sub.3, Sn(Sb)O.sub.2, SnO.sub.2, ZrO.sub.2, iron titanates, iron oxide hydrates, titanium suboxides, bismuth vanadate, cobalt aluminate, or any mixture thereof.

7. The pigment of claim 1, wherein the first coating comprises a sulfide of tin, silver, lanthanum, or rare earth metal.

8. The pigment of claim 1, wherein the second coating comprises SiO.sub.2, MgF.sub.2, Al.sub.2O.sub.3, AlOOH, B.sub.2O.sub.3, or a mixture thereof.

9. The pigment of claim 1, wherein the third coating comprises a colorless or colored metal oxide.

10. The pigment of claim 1, wherein the third coating comprises TiO.sub.2, Fe.sub.2O.sub.3, TiFe.sub.2O.sub.5, Fe.sub.3O.sub.4, BiOCl, CoO, Co.sub.3O.sub.4, Cr.sub.2O.sub.3, VO.sub.2, V.sub.2O.sub.3, Sn(Sb)O.sub.2, SnO.sub.2, ZrO.sub.2, iron titanates, iron oxide hydrates, titanium suboxides, bismuth vanadate, cobalt aluminate, or any mixture thereof.

11. The pigment of claim 1 further comprising interlayers of absorbing or nonabsorbing materials between the first coating, the second coating, and the third coating.

12. The pigment of claim 11, wherein the thickness of the interlayers is 1 to 30 nm.

13. A composition comprising the pigment of claim 1, wherein the composition is a paint, printing ink, plastic, cosmetic, ceramic, or glass.

14. A method of using the pigment of claim 1 comprising incorporating the pigment in a coating; a printing ink; a plastic; a cosmetic; or a glaze for a ceramic or a glass.

15. A method for preparing the pigment of claim 1 comprising applying the first coating, the second coating, and the third coating by wet chemical coating.

16. The interference pigment of claim 1 which is: Perlite/TiO.sub.2/SiO.sub.2/TiO.sub.2; Perlite/TiO.sub.2/SiO.sub.2/Fe.sub.2O.sub.3; Perlite/TiO.sub.2/SiO.sub.2/TiO.sub.2.Fe.sub.2O.sub.3; Perlite/TiO.sub.2/SiO.sub.2/(Sn,Sb)O.sub.2; Perlite/(Sn, Sb)O.sub.2/SiO.sub.2/TiO.sub.2; Perlite/Fe.sub.2O.sub.3/SiO.sub.2/(Sn, Sb)O.sub.2; Perlite/TiO.sub.2.Fe.sub.2O.sub.3/SiO.sub.2/TiO.sub.2.Fe.sub.2O.sub.3; Perlite/TiO.sub.2/SiO.sub.2/MoS.sub.2; Perlite/TiO.sub.2/SiO.sub.2/Cr.sub.2O.sub.3; Perlite/Cr.sub.2O.sub.3/SiO.sub.2/TiO.sub.2; Perlite/Fe.sub.2O.sub.3/SiO.sub.2/TiO.sub.2; Perlite/TiO.sub.2/Al.sub.2O.sub.3/TiO.sub.2; Perlite/Fe.sub.2TiO.sub.5/SiO.sub.2/TiO.sub.2; Perlite/TiO.sub.2/SiO.sub.2/Fe.sub.2TiO.sub.5/TiO.sub.2; Perlite/TiO suboxides/SiO.sub.2/TiO suboxides; Perlite/TiO.sub.2/SiO.sub.2/TiO.sub.2/SiO.sub.2/TiO.sub.2+Prussian Blue; Perlite/TiO.sub.2/SiO.sub.2/TiO.sub.2/SiO.sub.2/TiO.sub.2; or Perlite/TiO.sub.2/SiO.sub.2/TiO.sub.2/SiO.sub.2/TiO.sub.2/SiO.sub.2/TiO.sub.2.

Description

(1) Various features and aspects of the present invention are illustrated further in the examples that follow. While these examples are presented to show one skilled in the art how to operate within the scope of this invention, they are not to serve as a limitation on the scope of the invention where such scope is only defined in the claims. Unless otherwise indicated in the following examples and elsewhere in the specification and claims, all parts and percentages are by weight, temperatures are in degrees centigrade and pressures are at or near atmospheric.

EXAMPLES

Example 1

(2) 17 g of OptiMat 1735 are suspended in deionised water. The particles are let to settle during 30 minutes. The particles still in suspension are removed. This operation is repeated 5 times.

(3) Then the sediment material is dispersed in 300 ml of deionised water and heated at 90 C. The pH of the suspension is set at 1.5 and 20 ml of a solution comprising 9 g of SnCl.sub.4/5H.sub.2O, 5 g of 37% HCl, 1.00 g glycine and 100 g distilled water is added at a speed of 0.4 ml per minute while keeping the pH constant with continuous addition of 1 molar NaOH. Then the pH is set at 1.8 and 467 ml of a solution comprising 34.00 g of TiOCl.sub.2, 32 g of 37% HCl, 5.22 g glycine and 445 g distilled water are added at a speed of 1 ml per minute while keeping the pH at 1.8 with 1 M NaOH. 13.3 g of a bright blue powder, which shows a flop toward violet, are obtained after filtration, drying and calcination in air at 750 C. It was confirmed by X-ray spectroscopy that the coating consists of rutile TiO.sub.2.