Pearlescent pigments on the basis of fine and thin synthetic substrates

Patent metadata

Field	Value
Publication number	US-10125261-B2
Application number	US-201013501497-A
Country	US
Kind code	B2
Filing date	Oct 10, 2010
Priority date	Oct 14, 2009
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

The invention relates to pearlescent pigments comprising a largely transparent platelet-shaped synthetic substrate having a density ρ S and at least one optically active coating having a density ρ M , the substrate having an average size d 50 from a range from 2.0 μm to 8.0 μm and an average height h S from a range from 40 nm to 110 nm and the total lead content of the pearlescent pigments is ≤10 ppm. The invention further relates to a method for producing the pearlescent pigments, and also to the use thereof.

First claim

The invention claimed is:

1. Pearlescent pigments comprising transparent platelet-shaped synthetic substrates having a density ρ S and at least one optically active coating having a density ρ M ,
wherein the transparent platelet-shaped synthetic substrates are synthetic mica,
wherein the d 50 value of the cumulative frequency distribution of the substrates volume-average size distribution obtained by, laser diffraction is within the range of 2.1 μm to 7.0 μm and an average height h S within the range of 40 nm to 110 nm, the standard deviation in the average height h S is from 25% to 80%, and the total lead content of the pearlescent pigments is ≤10 ppm by weight ratio,
wherein the optically active coating comprises at least one metal oxide layer, and optionally at least one of a metal hydroxide layer(s) or a metal oxide hydrate layer(s), and
wherein the metal oxide layer consists of metal oxides consisting of titanium oxide and optionally one or more of iron oxide, cerium oxide, chromium oxide, tin oxide, zirconium oxide, or cobalt oxide, the relationship between the titanium oxide content in % by weight, based on the total weight of titanium oxide and synthetic mica, and the average layer thickness of the metal oxide layer is as follows:
a titanium oxide content of 30-80% by weight for an average metal oxide layer thickness of 20 nm to 50 nm;
a titanium oxide content of 50-85% by weight for an average metal oxide layer thickness of greater than 50 nm to 75 nm;
a titanium oxide content of 59-89% by weight for an average metal oxide layer thickness of greater than 75 nm to 95 nm;
a titanium oxide content of 66-92% by weight with an average metal oxide layer thickness of greater than 95 nm to 125 nm; or
a titanium oxide content of 69-96% by weight with an average metal oxide layer thickness of greater than 125 nm to 215 nm.

2. The pearlescent pigments of claim 1 , wherein the pearlescent pigments have a size distribution with a d 90 value within the range of 5.0 μm to 11.0 μm.

3. The pearlescent pigments of claim 1 , wherein the optically active coating is a high-index coating having a refractive index n M >2.0.

4. The pearlescent pigments of claim 1 , wherein the average substrates height h S is determined by the following formula:

h
S

=

4
⁢

⁢

d
M
3

3
⁢

⁢

r
S
2

+

π
⁢

⁢

d
M
2

r
S

+

2
·

d
M

ρ
S

ρ
M

·

(

100

c
M

-
1

)

-

(

d
M

r
S

)

2

-

2
·

d
M

r
S

.

wherein the average geometric layer thickness of the optically active coating, d M is 40 nm to 180 nm,
r S =d 50 /2 is the average radius of the substrates, determined via laser diffraction methods,
ρ S is the density of the substrates and ρ M is the density of the optically active coating and c M is the weight fraction in % of the optically active coating, determined via analytical measurements, based on the total weight of substrates and optically active coating.

5. A method for producing the pearlescent pigments of claim 1 , comprising:
a) classifying transparent platelet-shaped synthetic substrates, in order to obtain substrates having a d 50 value of the cumulative frequency distribution of the substrates volume-average size distribution within the range of 2.1 μm to 7.0 μm, as determined by laser diffraction, an average height h S from a range of 40 nm to 110 nm, the standard deviation in the average height h S is from 25% to 80%, and the total lead content of the pearlescent pigments is ≤10 ppm by weight ratio; and
b) coating the classified transparent platelet-shaped synthetic substrates obtained in a) with at least one optically active coating comprising at least one metal oxide layer, in order to obtain pearlescent pigments comprising transparent platelet-shaped synthetic substrates having a density ρ S and at least one optically active coating having a density ρ M .

6. A coating composition comprising the pearlescent pigments of claim 1 .

7. The pearlescent pigments of claim 1 , wherein the titanium oxide is in the anatase modification.

8. The coating composition of claim 6 , wherein the coating composition is a paint, printing ink, inkjet ink, toner, cosmetic, plastic, textile, glass, enamel, glaze or ceramic.

9. The coating composition of claim 6 , wherein the coating composition is a cosmetic product.

10. A cosmetic product comprising the pearlescent pigments of claim 1 .

Assignees

• Schmidt Ulrich
• Gruner Michael
• Schumacher Dirk
• Kaupp Gunter
• Mendler Barbara
• Eckart Gmbh

Inventors

• Schmidt Ulrich
• Gruner Michael
• Schumacher Dirk
• Kaupp Gunter
• Mendler Barbara

Classifications

• A61Q3/02

  Nail coatings · CPC title

• C09C2200/1004

  the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2 · CPC title

• C09C2200/102

  the core consisting of glass or silicate material like mica or clays, e.g. kaolin · CPC title

• C09C2220/106

  comprising only a drying or calcination step of the finally coated pigment · CPC title

• A61K2800/436

  Interference pigments, e.g. Iridescent, Pearlescent · CPC title