Aqueous dispersions of acicular titanium dioxide
AssigneeTioxide Group Limited
InventorJenifer L. Robb
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Abstract
An aqueous dispersion of acicular fine particle size titanium dioxide containing from 20 to 60% by weight solids content and a polycarboxylic dispersant is of outstanding use in the preparation of sun screens. The dispersions are transparent to visible light and absorbant to UV light of broad spectrum. Usually the titanium dioxide has a largest dimension within the range 0.01 to 0.15 micron. The dispersions are produced by milling, preferably in a high speed mill, until the required UV absorbancy is attained.
Claims34
An aqueous dispersion of titanium dioxide comprising water, particles of titanium dioxide having an acicular shape and a dispersing agent selected from the group consisting of polymers or copolymers of an acrylic acid or substituted acrylic acid and salts of said polymers or copolymers and said titanium dioxide being present in an amount to produce a solids content for the dispersion of from 20 to 60 percent by weight and having a size such that the dispersion is substantially transparent to visible light and has a maximum extinction coefficient (E(max)) in the ultra violet range of wavelengths of at least 30 liters per gm per cm.
An aqueous dispersion of titanium dioxide comprising water, particles of titanium dioxide having an acicular shape and having a ratio of the largest dimension to the shortest dimension within the range 8:1 to 2:1 and wherein the longest dimension is within the range 0.01 to 0.15 microns and a dispersing agent selected from the group consisting of polymers or copolymers of an acrylic acid or substituted acrylic acid and salts of said polymers or copolymers and said titanium dioxide being present in an amount to produce a solids content for the dispersion of from 20 to 60 percent by weight.
A method for the manufacture of an aqueous dispersion comprising milling in the presence of particulate grinding medium particulate titanium dioxide in water in the presence of a dispersing agent selected from the group consisting of polymers or copolymers of an acrylic acid or substituted acrylic acid and salts of said polymers or copolymers, said titanium dioxide having an acicular shape and is present in an amount sufficient to produce a solids content of from 20 to 60 percent by weight until the titanium dioxide is dispersed in said water to produce a product absorbent to ultraviolet light and substantially transparent to visible light.
Dependencies are inferred from the claim text.