Patent ID: 7699927

Claim:
A pearlescent pigment comprising platelet-shaped substrate, comprising metal oxide, and protective layer that is from 2 nm to 20 nm thick, said metal oxide having a refractive index of more than 1.8, wherein the protective layer is applied directly to the substrate and consists of an modified only one single SiO2 layer that is composed exclusively of SiO2, wherein the SiO2 content of the pigment is 0.5% to 10% by weight based on the total weight of the pigment, does not include any metal compound other than SiO2 and includes an organic chemical surface modification, the organic chemical surface modification being applied on the SiO2 layer, wherein the SiO2 layer is surface modified with organofunctional silanes, wherein the organofunctional silanes comprise at least one silane having at least one functional bond group, wherein at least one functional bond group is selected from the group consisting of acrylate, methacrylate, vinyl, amino, cyanate, isocyanate, epoxy, hydroxyl, thiol, ureido, carboxyl groups, and mixtures thereof, and at least one silane without a functional bond group, wherein the silane without a functional bond group is an alkylsilane having the formula (I): R (4-z) Si(X) z (I) wherein: z is an integer from 1 to 3; R is a substituted or unsubstituted, unbranched or branched alkyl chain having 0 to 22 carbon atoms; and X is a halogen and/or alkoxy group, or the silane without a functional bond group has a structural formula (II): (R 1 —X—[A—Y] n —B) (4-z) Si(OR 2 ) z (II) wherein: n=1 to 100; z is an integer from 1 to 3; R 1 is a straight- or branched-chain alkyl having 1 to 12 carbon atoms, which may be substituted by one or more halogen atoms; an aryl having 6 to 12 carbon atoms; or an aryl having 6 to 12 carbon atoms, which is substituted by alkyl having 1 to 6 carbon atoms, halogen atoms, or a combination thereof; R 2 is a straight- or branched-chain alkyl having 1 to 6 carbon atoms; A and B are independently a divalent group composed of straight- or branched-chain alkylene having 1 to 12 carbon atoms; an arylene having 6 to 12 carbon atoms; or an arylene having 6 to 12 carbon atoms, which is optionally substituted by alkyl having 1 to 6 carbon atoms, halogen atoms, or a combination thereof; and X and Y and are independently O or S.