The invention relates to particles with an opalescent effect, which have a particle size in the range from 5 .mu.m to 5000 .mu.m, comprising monodisperse spheres having a diameter of 50 nm to 2 .mu.m with a standard deviation of less than 5% in a packed and regularly ordered structure which is three-dimensional in terms of domains and is mechanically stabilized by physical or chemical modification.

The application relates to pigments based on plate-like substrates which, if desired, are covered with one or more layers comprising metal oxides or metal oxide mixtures, zinc oxide being deposited on the surface of the substrates with the formation of a not entirely continuous layer.

A method of preparing a stable suspension of a natural calcium carbonate pigment in water which comprises (a) forming an aqueous suspension containing from 70 to 85 percent by weight of natural calcium carbonate pigment, the natural calcium carbonate pigment comprising not more than 1 percent by weight of particles having an equivalent spherical diameter larger than 53 microns, and a dispersing agent which is a water-soluble anionic polymer, and (b) thoroughly agitating said suspension in the pr...

The invention provides novel nacreous pigments comprising a plurality of high refractive index layers of titanium or zirconium dioxide or of an alkaline earth metal titanate separated by one or more layers of lower refractive index of an organic film-forming substance or of an inorganic oxide or hydroxide. These pigments are made by successively depositing the various layers on a support, stripping the product from the support and comminuting it.

Pellets of titanium dioxide, the particles of the titanium dioxide having a coating of one or more hydrous oxides in the total amount of at least 3.5 percent by weight of TiO.sub.2, preferably the particles of titanium dioxide have a coating of hydrous oxide in a total amount of at least 5 percent and may be up to 35 percent by weight of TiO.sub.2.

Pigmentary titanium dioxide coated with a propane diol in an amount of from 0.05 to 3 percent by weight. The particles can also be coated with one or more hydrous metal oxides.

A process for the manufacture of a pigment concentrate which comprises dispersing dry organic pigment granules in an organic vehicle.

Pigment of the general formula: where F is the cation of a cationic dye which has an absorption maximum at >700 nm and may or may not contain anionic groups and Het is an anion of a heteropolyacid based on tungsten, molybdenum, vanadium or a mixture of these with phosphorus, silicon, cobalt, aluminum, manganese, chromium, nickel or a mixture of these or a copper (I)-hexacyanoferrate(II) anion, are superior to the known IR dyes in terms of thermal stability and photostability, and give optical...

Pigments of the general formula where F is the cation of a cationic dye which has an absorption maximum at >700 nm and may or may not contain anionic groups and Het is an anion of a heteropolyacid based on tungsten, molybdenum, vanadium or a mixture of these with phosphorus, silicon, cobalt, aluminum, manganese, chromium, nickel or a mixture of these or a copper(I)-hexacyanoferrate(II) anion, are superior to the known IR dyes in terms of thermal stability and photostability, and give optical ...

A new process for the production of pigments suitable for use in paper laminates has been developed in which a metal oxide is treated with a water-soluble salt of zinc and a phosphate or phosphoric acid and subsequently with an alkali metal aluminate in such a manner that there is deposited on the metal oxide a coating containing zinc and phosphate ions together with aluminium ions. The pH of the dispersion following the metal oxide is maintained at a value not exceeding 8.0 during precipitation...