Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1998-02-12
2000-06-13
Koslow, C. Melissa
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
106437, 423610, 423611, 423615, 423616, C01B 23047
Patent
active
060744723
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to titanium dioxide pigments, obtainable by complete hydrolysis of a hydrolyzable titanium compound at from 0 to 100.degree. C. with intensive stirring and with setting of a pH in the range from 3 to 8 and maintenance of this pH within a range of 0.3 units.
The invention further relates to such titanium dioxide pigments coated with a physiologically tolerable inorganic compound reducing the photo effect of titanium dioxide, to a process for the preparation of such uncoated and coated titanium dioxide pigments, to their use for cosmetic and medicinal purposes, to cosmetic preparations and essentially anhydrous dispersions which comprise such coated and uncoated titanium dioxide pigments, and to a process for the preparation of such dispersions.
The use of titanium dioxide pigments in cosmetics, in particular sunscreen compositions, is generally known, for example from Rompp Chemie Lexikon (Rompp's Chemical Encyclopedia), 9th Edition, Thieme Verlag, Stuttgart/New York, 1992, p. 4630.
Sunscreen compositions are generally understood as meaning compositions for the protection of the human skin from harmful effects of solar radiation, in particular of ultraviolet radiation (UV), which is subdivided according to its biological action into the ranges UV-A (wavelength 400-320 nm), UV-B (320-280 nm) and UV-C (280-200 nm) (Rompp, loc. cit., p. 4804). A sunscreen composition specifically has the task of allowing the UV-A responsible for the tanning of the skin to pass unchanged and, on the other hand, of stopping the UV-B, which can cause skin damage; UV-C, however, is absorbed in the atmosphere to the greatest possible extent (Rompp, loc. cit., p. 4213).
The preparation of titanium dioxide pigments suitable as sunscreen compositions is generally known, for example from GB-A 2206339.
To this end, ilmenite (FeTiO.sub.3) is decomposed using concentrated sulfuric acid, the decomposition cake is dissolved in water and the iron(III) present is reduced chemically to iron(II). After a crystallization and filtration step, the solution is concentrated under reduced pressure and then hydrolyzed in the presence of heat to precipitate the titanium dioxide. After the neutralization of the solution with sodium hydroxide solution, the titanium dioxide is filtered off and washed with water.
After a wet milling of the titanium dioxide, the pigments can be coated, if desired, with an inorganic compound. The product is then dried at 110.degree. C.
The pigments can be suspended in numerous solvents with the aid of dispersants and high-speed ball mills.
Pigments of this type are indeed suitable for sunscreen compositions; however, they have an undesirably high UV-A absorption compared with the desired UV-B absorption and a low transparency in the visible light range.
It is an object of the present invention to prepare titanium dioxide pigments which have, compared with a desirable UV-B absorption, a low UV-A absorption and high transparency in the visible light range, in a technically simple and cost-effective manner.
We have found that this object is achieved by the titanium dioxide pigments defined at the outset.
The titanium dioxide pigments can be obtained by complete hydrolysis of hydrolyzable titanium compounds. Suitable hydrolyzable titanium compounds are organic compounds such as complex compounds, for example titanyl acetylacetonate and titanocene dichloride, titanic acid esters, for example titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide and titanium cresoxide, and also organic titanium salts, for example titanium stearate and titanium oxalate, and preferably inorganic compounds such as titanyl sulfate, titanium fluoride, titanium bromide, titanium iodide and, in particular, titanium tetrachloride or mixtures of such compounds. Compounds of this type are known.
During the hydrolysis, according to the invention a pH of from 3 to 8, in particular from 3 to 5, measured with a glass electrode, is maintained, where the pH during the hydrolysis reaction
REFERENCES:
patent: 3898321 (1975-08-01), Marsh
patent: 4073877 (1978-02-01), Klein et al.
patent: 5453267 (1995-09-01), Kemp et al.
patent: 5468471 (1995-11-01), Zecchino et al.
patent: 5643557 (1997-07-01), Eteve et al.
patent: 5658555 (1997-08-01), Ascione et al.
patent: 5695747 (1997-12-01), Forestier et al.
patent: 5733895 (1998-03-01), Forestier et al.
Chem. Abst., vol. 116, No. 2, Jan. 13, 1992, Abst. No. 847&v, p. 108.
Romp Chemie Lexicon, 9 Edition, Thieme Verlag, 1992, p. 4630.
Romp Chemie Lexicon, 9 Edition, Thieme Verlag, 1992, p. 4804.
Romp Chemie Lexicon, 9 Edition, Thieme Verlag, 1992, p. 4213.
Dausch Wilma
Jachow Harald
Kormann Claudius
Schwab Ekkehard
Sperling Karin
BASF - Aktiengesellschaft
Koslow C. Melissa
LandOfFree
Hydrolytic preparation of titanium dioxide pigments does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydrolytic preparation of titanium dioxide pigments, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydrolytic preparation of titanium dioxide pigments will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2065262