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Grinding aids for micronized organic UV absorbers

IP.com Disclosure Number: IPCOM000187464D
Publication Date: 2009-Sep-07

Publishing Venue

The IP.com Prior Art Database

Abstract

A method of preparing a composition, comprising (a) a micronised insoluble organic UV absorber, which method comprises grinding the insoluble organic UV absorber, in coarse particle form, in a grinding apparatus, in the presence of a grinding aid selected from the groups (b1) carboxylic acids and their salts; (b2) fatty acid esters (b3) alkyl phosphates or phosphoric acid esters; (b4) ethoxylated carboxylic acids or polyethyleneglycol (PEG) esters; (b5) fatty alcohol polyethyleneglycol (PEG) ethers of fatty alcohols; (b6) polyethylene/polypropylene –glycol ethers of saturated or unsaturated C4 - C28 fatty ; (b7) ethoxylated alkylphenols or ethoxylated alkylphenyl ethers; (b8) esters of polyol and mono-, di- or tri-glycerides ; (b9) esters of fatty acids and saccharose ; (b10) sorbitan mono- and di-esters of saturated and/or unsaturated C6 - C22 fatty acids and ethylene oxide groups ; and (b11) surfactants which are mainly acting as detergent or cleansing agents.

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Grinding aids for micronized organic UV absorbers

The present invention relates to a method for producing new formulations of UV absorbers

and to their use in sunscreen compositions which, in turn, are useful, in particular, for the

protection of human skin.

It has long been known that prolonged exposure to that UV radiation which reaches the surface of the

earth can lead to the formation of erythemas or light dermatoses, as well as to an increased incidence

of skin cancers or accelerated skin aging.

Various sunscreen formulations have been proposed which include a material which is intended to

counteract UV radiation, thereby inhibiting the said undesired effects on the skin.

A great number of compounds has been proposed for use as UV protectants in sunscreen

formulations, especially soluble organic UV absorbers and insoluble micronised inorganic compounds,

in particular zinc oxide and titanium dioxide.

The high specific weight of insoluble inorganic compounds, such as zinc oxide and titanium dioxide

leads to a reduced stability of formulations containing them. Moreover, such inorganic compounds

have been claimed to generate toxic radicals under the influence of light ("Redox Mechanisms in

Heterogeneous Photocatalysis", Serpone et al, Electrochemistry in Colloids and Dispersions, Editors

Mackay and Texter, VCH Publishers Inc., NewYork 1992).

Micronised, insoluble organic UV absorbers, when used in sunscreen formulations, provide excellent

UV protection and have a high SPF rating. Moreover, micronised, insoluble organic UV absorbers

show no tendency, under the influence of light, to generate radicals which could damage or sensitise

human skin.

Accordingly, the present invention provides a method of preparing a composition,

comprising (a) a micronised insoluble organic UV absorber, which method comprises

grinding the insoluble organic UV absorber, in coarse particle form, in a grinding apparatus,

in the presence of a grinding aid (b) selected from the groups

(b1) carboxylic acids and their salts;

(b2) fatty acid esters

(b3) alkyl phosphates or phosphoric acid esters;

(b4) ethoxylated carboxylic acids or polyethyleneglycol (PEG) esters;

(b5) fatty alcohol polyethyleneglycol (PEG) ethers of fatty alcohols;

(b6) polyethylene/polypropylene -glycol ethers of saturated or unsaturated C4 - C28 fatty acids;

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(b7) ethoxylated alkylphenols or ethoxylated alkylphenyl ethers;

(b8) esters of polyol and mono-, di- or tri-glycerides;

(b9) esters of fatty acids and saccharose;

(b10) sorbitan mono- and di-esters of saturated and/or unsaturated C6 - C22 fatty acids and ethylene

oxide groups; and

(b11) surfactants which are mainly acting as detergent or cleansing agents.

Preferably the micronised insoluble organic UV absorber is selected from the compounds of formula

(1)

A1

A1

A1

N

N

, wherein

A is a radica...