Process for preparing flake-form pigments based on aluminum and on Sioz(Z=0.7-2.0) comprising forming a layer of separating agent
The present invention relates to process for the production of plane-parallel platelets, comprising the steps of: a) vapor-deposition of a separating agent onto a carrier to produce a separating agent 5 layer, b) vapor-deposition of at least one product layer onto the separating agent layer, and c) dissolution of the separating agent layer in a solvent and production of a suspension in which the at least one product layer is present in the form of plane-parallel platelets, wherein the separating agent is selected from the group consisting of anthracene, anthraquinone, acetamidophenol, acetylsalicylic acid, camphoric anhydride, benzimidazole, benzene-1,2,4-tricarboxylic acid, biphenyl-2,2-dicarboxylic acid, bis(4-hydroxyphenyl)sulfone, dihydroxyanthraquinone, hydantoin, 3-hydroxybenzoic acid, 8-hydroxyquinoline-5-sulfonic acid monohydrate, 4-hydroxycoumarin, 7-hydroxycoumarin, 3-hydroxynaphthalene-2-carboxylic acid, isophthalic acid, 4,4-methylene-bis-3-hydroxynaphthalene-2-carboxylic acid, naphthalene-1,8-dicarboxylic anhydride, phthalimide and its potassium salt, phenolphthalein, phenothiazine, saccharin and its salts, tetraphenylmethane, triphenylene, triphenylmethanol, and also mixtures of at least two of those substances, especially pentaerythritol (C(CH 2 OH) 4 ), trimesic acid (=1,3,5 benzene tricarboxylic acid), DL-alanine, DL-valine, 2,6-20 diaminopurine, ascorbic acid, 1,3,5-benzenetricarboxylic acid, o-acetylsalicyclic acid, diphenic acid, terephthalic acid, pyrogallol, cyanuric acid, hexamethyltetramine (urotropin), fumaric acid, and 4-acetylbenzoic acid and also mixtures of at least two of those substances.
1. A process for the production of plane-parallel platelets, comprising the steps:
a) vapour-deposition of a separating agent onto a carrier to produce a separating agent layer,
b) vapour-deposition of at least one product layer onto the separating agent layer, and
c) dissolution of the separating agent layer in a solvent and production of a suspension in which the at least one product layer is present in the form of plane-parallel platelets, wherein the separating agent is selected from the group consisting of pentaerythritol, DL-alanine, DL-valine, 2,6-diaminopurine, ascorbic acid, cyanuric acid, hexamethyltetramine, fumaric acid, and mixtures thereof.
2. The process according to claim 1 , wherein the separating agent is selected from hexamethyltetramine.
3. The process according to claim 1 , wherein the separating agent is pentaerythritol.
4. The process according to claim 1 , wherein the plane-parallel platelets are aluminum flakes, comprising the steps:
a) vapor-deposition of a separating agent onto a carrier to produce a separating agent layer,
b) vapor-deposition of an Al layer onto the separating agent layer,
c) dissolution of the separating agent layer in a solvent and
d) separation of the aluminum flakes from the solvent;
or
the plane-parallel platelets are SiO z , coated aluminum flakes, comprising
(A1) a layer consisting of SiO z ,
(B) a layer consisting of aluminum on the layer (A1) and
(A2) a layer consisting of SiO z , on the layer (B),
wherein 0.70≦z≦2.0, comprising the steps:
a) vapor-deposition of a separating agent onto a carrier to produce a separating agent layer,
b1) vapor-deposition of an SiO y layer onto the separating agent layer,
b2) vapor-deposition of an Al layer onto the SiO y layer,
b3) vapor-deposition of an SiO y layer onto the Al layer,
c) dissolution of the separating agent layer in a solvent and
d) separation of the SiO y -coated aluminum flakes from the solvent, wherein 0.70≦y≦1.95.
5. The process according to claim 4 , wherein the separating agent is pentaerythritol and the solvent is water.
6. The process according to claim 1 , wherein the plane-parallel platelets are SiO z flakes, wherein 0.70≦z≦2.0, comprising the steps:
a) vapor-deposition of a separating agent onto a carrier to produce a separating agent layer,
b) vapor-deposition of an SiO y layer onto the separating agent layer,
c) dissolution of the separating agent layer in a solvent and
d) separation of the SiO y flakes from the solvent, wherein 0.70≦y≦1.95.
7. The process according to claim 6 , wherein the separating agent is pentaerythritol and the solvent is water.