Process for producing nanoparticles

Abstract

A composition comprises surface-modified nanoparticles of at least one amphoteric metal oxide or oxyhydroxide. The nanoparticles bear, on at least a portion of their surfaces, a surface modification comprising (i) at least one surface modifier selected from lactate, thiolactate, and mixtures thereof, and (ii) at least one surface modifier selected from halide, nitrate, acetate, carbonate, formate, propionate, sulfate, bromate, perchlorate, tribromoacetate, trichloroacetate, trifluoroacetate, carboxylate comprising from one to about four alkyleneoxy moieties, chlorate, and mixtures thereof.

Description

[0001] priority statement [0002] This patent application claims priority to US Provisional Application Nos. 61 / 015,990 and 61 / 016,048, filed December 21, 2007, the contents of which are hereby incorporated by reference. technical field [0003] The present invention relates to a process for the preparation of metal oxide or metal oxyhydroxide particles. Background technique [0004] Metal oxides have a variety of uses. In particular, zinc oxide can be used for various purposes including, for example, as a white pigment, a catalyst, one of the components of antibacterial skin protection ointments, and an activator of rubber vulcanization. Sunscreens and wood varnishes contain finely divided zinc oxide as an ultraviolet (UV) absorbing pigment. [0005] Zinc oxide is used as a UV absorber because it does not degrade when exposed to UV light for a long time. However, when the zinc oxide particle size is less than about 20 nanometers (nm), its energy bandgap shifts to highe...

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Problems solved by technology

However, the starting salt typically requires the use of dilute solutions to avoid relatively high rates of agglomeration, and zinc oxide grown from the salt tends to form agglomerates unsuitable for applications requiring transparency

[0012] Other methods of making nano-sized zinc oxide particles use expensive raw materials (such as zinc alkoxides), require the use of emulsifiers, are complex, generate agglomerates, slow particle growth, have insufficient control over particle size, and / or do not achieve the generally preferred particle size (e.g., an average primary particle size of about 5 nm to about 30 nm)

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