Huls Aktiengesellschaft

Kronos International, Inc.

Kronos, Inc.

Kronos (u.s.a.), Inc.

Lothar Elfenthal

Burkhard Standke

Jaroslaw Monkiewicz

Michael Horn

Peter Jenkner

Roland Edelmann

Ralf Laven

Siegfried Bluemel

Albert Frings

Volker Schmitt

Lydia Drews-Nicolai

Franz Rosendahl

Edgar Klein

Hans-Hermann Luginsland

Manfred Kluwig

Rolf Schwindt

A method and material for improved TiOpigment for paper and laminates is described. Phosphorous, titanium, and aluminum compounds are successively added to a TiOpigment suspension. Resulting pigments show improved greying resistance and hiding power over prior art pigments, and show improved results as pigments in tests of paper and laminates.

Method for the surface treatment of a titanium dioxide pigment

A mixture of oligomers of alkylalkoxysilanes condensed in the chain and/or cyclic form, said mixture of oligomers containing less than 2% by weight of free alcohols and the condensed alkoxysilanes satisfying formula I: ##STR1## wherein R is an alkyl group having 3 to 18 carbon atoms, and each R' is a member (i) selected from the group consisting of methyl, ethyl or hydrogen, or is (ii) methyl or hydrogen, or is (iii) ethyl or hydrogen, the degree of oligomerization being in the range 2.ltoreq.x.ltoreq.20 and the quotient of the molar ratio �Si/alkoxy group!.gtoreq.1; and/or

Mixture of oligomers of condensed alkylalkoxysilanes

Subpigmentary titanium dioxide with decreased photoactivity is produced if known ions for increasing photostability in titanium dioxide pigments are not deposited on the surface of the subpigmentary particles, but instead are included intracrystallinely in the pigment particle (i.e., doped). In a preferred process for preparation of doped subpigmentary titanium dioxide particles, an acid solution containing the dopant is added in two stages to a suspension of subpigmentary titanium dioxide.

Subpigmentary titanium dioxide with improved photostability

A process produces fine particle titanium dioxide essentially transparent to visible light and essentially UV radiation absorbing. During preparation of the titanium dioxide product, tin dioxide with a particle size of 1 to 10 nm, and preferably 1 to 4 nm, is added, in an amount of 0.5 to 10 weight percent with respect to TiO.sub.2. The particle size of the titanium dioxide is specifically adjusted by the tin dioxide addition. Acicular particles are rounded by heat-treatment between 300.degree. and 800.degree. C., and preferably between 400.degree. and 600.degree. C. The particles can be post-treated to produce a coating of inorganic and/or organic substances. The fine particle titanium dioxide can be prepared by the decomposition of sodium titanate with hydrochloric acid or by suitable hydrolysis of a tetravalent titanium compound which leads to rutile formation. A currently preferred way of adding the tin dioxide is as a colloidal sol which is prepared by the reaction of tin tetrachloride with water at a maximum of 22.degree. C.

Process for the production of a fine particle titanium dioxide

Growing community of inventors

Langenfeld, Germany

Lothar Elfenthal