# US 8,772,371 B2 · Pearlescent pigments coated with a metal oxide/hydroxide layer and an acrylic copolymer

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- Number: US 8,772,371 B2
- Document ID: US8772371B2
- Status: Granted
- Kind: B2
- Application number: 12/990,813
- Filed: 2009-04-28
- Published: 2011-05-19
- Granted: 2014-07-08
- Earliest claimed: 2008-05-09
- Assignees: BASF SE
- Applicants: Philippe Bugnon; Karin Karrer; Patrice Bujard
- Inventors: Philippe Bugnon; Karin Karrer; Patrice Bujard
- Web page: https://patentgrep.com/patent/US8772371B2

## CPC

- C09C 1/0021: {comprising a core coated with only one layer having a high or low refractive index}
- C09C 1/0024: {comprising a stack of coating layers with alternating high and low refractive indices, wherein the first coating layer on the core surface has the high refractive index}
- C09D 5/032: {characterised by a special effect of the produced film, e.g. wrinkle, pearlescence, matt finish}
- C09D 5/36: Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
- C09D 7/62: modified by treatment with other compounds
- C09D 7/70: {characterised by shape, e.g. fibres, flakes or microspheres}
- C09D 11/037: characterised by the pigment
- C01P 2004/54: Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
- C08K 3/34: Silicon-containing compounds
- C08K 3/346: {Clay}
- C08K 9/02: Ingredients treated with inorganic substances
- C08K 2003/2241: {Titanium dioxide}
- C08K 2003/2272: {Ferric oxide (Fe2O3)}
- C09C 2200/1004: the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2
- C09C 2200/102: the core consisting of glass or silicate material like mica or clays, e.g. kaolin
- C09C 2200/1037: the core consisting of an inorganic suboxide or a mixture thereof, e.g. SiOx or TiOx
- C09C 2200/1054: the core consisting of a metal
- C09C 2200/1062: the core consisting of an organic compound, e.g. Liquid Crystal Polymers [LCP], Polymers or natural pearl essence
- C09C 2200/401: Inorganic protective coating
- C09C 2200/402: Organic protective coating
- C09C 2200/405: High molecular weight materials, e.g. polymers
- C09C 2220/10: Wet methods, e.g. co-precipitation
- C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS}
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

The invention relates to pearlescent pigments comprising a platelet-shaped substrate, a metal oxide coating comprising a metal oxide layer having a refractive index of greater than 1.8 and a protective layer, wherein the protective layer comprises a metal oxide/hydroxide layer and optionally boroxide, applied to which is an organic aftercoat of an acrylic copolymer, to a method for producing said pigments and the use thereof. The outer layer provides a very good photo-stabilisation of the TiO2 coated platelet-shaped substrates, such as mica, combined with a good water resistance and an anti-yellowing performance.

## Claims

### Claim 1

A pearlescent pigment comprising a platelet-shaped substrate, a metal oxide coating comprising:
a metal oxide layer having a refractive index of greater than 1.8; and
a protective layer,
wherein the protective layer comprises a metal oxide/hydroxide layer and optionally boroxide, applied to which is an organic aftercoat of an acrylic copolymer,
wherein the metal oxide/hydroxide of the protective layer is selected from oxides/hydroxides of silicon (silicon oxide, silicon oxide hydrate), aluminium, zirconium, magnesium, calcium, iron(III), yttrium, cerium, zinc and combinations thereof, and
wherein the acrylic copolymer comprises as copolymerized units the following monomers
(A) an ethylenically unsaturated monomer containing at least one amino group;
(B) an ethylenically unsaturated monomer containing no amino group;
(C) optionally a hydroxy- or alkoxyalkyl(meth)acrylate of the formula
CH2═CH(R1)—COO—C1H2t—OR2
(D) a (poly)alkyleneglycolmono(meth)acrylate of the formula
CH2═CH(R1)—COO—(CmH2mO)—OR2
wherein R1 is hydrogen or methyl and R2 is hydrogen or C1-C6alkyl, t is an integer of 2, 3, 4, 5 or 6; and m is an integer of 2 or 3 and n is an intekger of 2 to 20.

### Claim 2 (depends on 1)

The pearlescent pigment according to claim 1, wherein the metal oxide/hydroxide content (protective layer) of the pigment is in the range of from 0.1 to 10% by weight, based on the total weight of the pigment.

### Claim 3 (depends on 1)

The pearlescent pigment according to claim 1, wherein the acrylic copolymer content of the pigment is in the range of from 0.1 to 10% by weight, based on the total weight of the pigment.

### Claim 4 (depends on 1)

The pearlescent pigment according to claim 1, wherein the platelet-shaped substrate is selected from natural micaceous iron oxide, synthetic and doped micaceous iron oxide, natural, and synthetic mica, another layered silicate, basic lead carbonate, flaky barium sulfate, MoS2, SiO2, Al2O3, TiO2, glass, perlite, ZnO, ZrO2, SnO2, BiOC1, chromium oxide, BN, MgO flakes, Si3N4, graphite, SiOz, SiO2/SiOx/SiO2 (0.03≦x≦0.95), SiO1.40-2.0/SiO0.70-0.99/SiO1.40-2.0, and Si/SiOz with 0.70≦z≦2.0; or the platelet-shaped substrate is selected from flakes of Ag, Al, Au, Cu, Cr, Fe, Ge, Mo, Ni, Si, Ti, and alloys thereof.

### Claim 5 (depends on 1)

The pearlescent pigment according to claim 1, wherein the pearlescent pigment comprising the platelet-shaped substrate and the metal oxide coating has the following layer structure:
TRASUB
TiO2
TRASUB
TiO2/Fe2O3
TRASUB
Fe2TiO5
TRASUB
TiO2
SiO2
TiO2
TRASUB
TiO2
SiO2
TiO2/Fe2O3
TRASUB
(Sn,Sb)O2
SiO2
TiO2
TRASUB
TiO2/Fe2O3
SiO2
TiO2/Fe2O3
TRASUB
Cr2O3
SiO2
TiO2
TRASUB
Fe2O3
SiO2
TiO2
TRASUB
TiO suboxides
SiO2
TiO suboxides
TRASUB
TiO2
SiO2
TiO2 + SiO2 + TiO2
TRASUB
TiO2 + SiO2 + TiO2
SiO2
TiO2 + SiO2 + TiO2
TRASUB
TiO2
Al2O3
TiO2
TRASUB
Fe2TiO5
SiO2
TiO2
TRASUB
TiO2
SiO2
Fe2TiO5/TiO2
TRASUB
STL
TiO2
wherein TRASUB is a transparent, or semitransparent substrate having a low index of refraction, another layered silicate, glass, Al2O3, SiOz, with 0.70≦z≦2.0, and STL is a semi-transparent layer.

### Claim 6 (depends on 1)

The pearlescent pigment according to claim 1, wherein the metal oxide/hydroxide layer consists of an oxide/hydroxide of aluminium, zirconium, or a mixture thereof; or ternary mixtures of zirconium oxide, aluminum oxide and zinc oxide, or zirconium oxide, aluminum oxide and magnesium oxide.

### Claim 7

A pearlescent pigment comprising a platelet-shaped substrate, a metal oxide coating comprising:
a metal oxide layer having a refractive index of greater than 1.8; and
a protective layer,
wherein the protective layer comprises a metal oxide/hydroxide layer and optionally boroxide, applied to which is an organic aftercoat of an acrylic copolymer,
wherein the metal oxide/hydroxide of the protective layer is selected from oxides/hydroxides of silicon (silicon oxide, silicon oxide hydrate), aluminium, zirconium, magnesium, calcium, iron(III), yttrium, cerium, zinc and combinations thereof, and
wherein the protective layer comprises 3 to 5% by weight aluminium oxide with 0.5 to 1.5% by weight boron oxide and about 5% by weight of the acrylic copolymer, each based on the weight of the pigment.

### Claim 8 (depends on 1)

The pearlescent pigment according to claim 1, wherein the protective layer comprises aluminium oxide and optionally boroxide.

### Claim 9 (depends on 1)

The pearlescent pigment according to claim 1, wherein the acrylic copolymer is a copolymer obtained by a process comprising the steps:
a1) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one nitroxylether having the structural element
wherein X represents a group having at least one carbon atom and is such that the free radical X. derived from X is capable of initiating polymerization; or
a2) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one stable free nitroxyl radical
and a free radical initiator;
wherein at least one monomer used in the steps al) or a2) is a C1-C6 alkyl or hydroxy C1-C6 alkyl ester of acrylic or methacrylic acid; and a second step
b) comprising the modification of the polymer or copolymer prepared under a1) or a2) by a transesterification reaction, an amidation, hydrolysis or anhydride modification or a combination thereof.

### Claim 10 (depends on 9)

The pearlescent pigment according to claim 9, wherein the acrylic copolymer is a copolymer of the formula shown below

### Claim 11 (depends on 1)

A process for producing the pigment according to claim 1, characterized in that
(a) pearlescent pigment comprising a platelet-shaped substrate, and a metal oxide coating comprising a metal oxide layer having a refractive index of greater than 1.8 is suspended in water, the pH of the suspension is adjusted to about 3, then an aqueous solution of one or more (metal) salts selected from boron, silicon, aluminium, zinc, calcium, magnesium, zirconium, iron(III), yttrium and cerium is added to the suspension while keeping its pH constant with an aqueous alkali solution, and after addition, its pH is adjusted to about 7 to 8.5, and
(b) a solution of the acrylic copolymer is added to the resulting suspension under stirring, and after addition, the suspension is filtered, washed with water and dried.

### Claim 12 (depends on 1)

Paints, lacquers, printing inks, powder coatings, paper coatings, plastics, cosmetics, inks, glazes for ceramics and glasses, comprising the pigment according to claim 1.