Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Patent
1998-06-22
2000-06-27
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
424489, 424 59, 424470, 424459, A61K 916, A61K 950
Patent
active
060804300
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates in general to powder coated with a sparingly soluble ultraviolet light absorber and particularly to powder coated with a sparingly soluble ultraviolet light absorber which can contain a high concentration of a sparingly soluble ultraviolet light absorber distributed homogeneously in the base agent, has superior stability over time and a high ultraviolet light protection effect.
BACKGROUND OF THE INVENTION
Sun tanning of the skin to a brown or light brown color is primarily done by the younger generations as an expression of healthy beauty or fashion and there are many people who want to be actively sun tanned. They apply a cosmetic on the whole body and expose the skin to intense sunlight. However, recently awareness of the importance of protecting the skin from ultraviolet light has risen and cosmetics have begun to contain an ultraviolet light absorber which absorbs ultraviolet light (wavelength 290-320 nm) known to cause blisters and erythema.
However, some ultraviolet light absorbers cannot exhibit their efficacy sufficiently although they have a high ultraviolet light absorption effect because the base agent can contain only a very small amount of them due to their very low solubility in solvents. Among them, Pongamia extract contains Pongamol which has a very strong ultraviolet light absorption effect and is expected to be useful as a ultraviolet light absorber (Japanese examined patent publication Tokko Hei 6-60092). However, its solubility is poor in all the base agents which are usually used as a base agent for cosmetics and therefore its application as it is in cosmetics and such has been very difficult.
DISCLOSURE OF THE INVENTION
Based on the aforementioned problem, the inventors conducted earnest research and discovered that a coating of a sparingly soluble ultraviolet light absorber can be formed on the surface of various kinds of powder by mixing the sparingly soluble ultraviolet light absorber with the powder in a specific manner and that, unlike the sparingly soluble ultraviolet light absorber itself, said powder can be added to a cosmetic base agent in a large amount and the stability over time is superior to when a non-sparingly soluble ultraviolet light absorber is added.
That is, the present invention provedes a powder coated with a sparingly soluble ultraviolet light absorber which comprises an inorganic or organic powder whose surface is coated with the sparingly soluble ultraviolet light absorber.
A preferable method of manufacturing it is to mix the melted sparingly soluble ultraviolet light absorber and inorganic powder or organic powder while heating and then gradually cool them to coat the surface of said powder with the sparingly soluble ultraviolet light absorber.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 shows the ultraviolet light transmittance of the powder coated with the sparingly soluble ultraviolet light absorber of the present invention in comparison with a simple blend.
FIG. 2 is a scanned image showing the powder structure of the pongamia-extract-coated sericite powder treated with the pongamia extract.
FIG. 3 is a scanned image showing the powder structure of sericite powder.
FIG. 4 shows the transmitted UV light spectra for cases where W/O emulsion type sunscreen agents of Example 8 and Comparative example 7 were irradiated with light of a prescribed intensity.
THE BEST MODES OF THE EMBODIMENTS
The configuration of the present invention is described below in detail.
A sparingly soluble ultraviolet light absorber used in the present invention refers to an ultraviolet light absorber whose solubility in isopropyl myristate at room temperature is 2% or less. The representative example of such a sparingly soluble ultraviolet light absorber is the pongamia extract. Additional examples include 4-(3,4-dimethoxyphenylmethylene)-2,5-dioxoimidazolidine-1-propionic acid 2-ethylhexyl ester (Softshade DH), dibenzoyl methane derivatives and Chalcone derivatives.
The Pongamia extract is a solvent extract of the seeds
REFERENCES:
patent: 4801445 (1989-01-01), Fukui et al.
patent: 5000945 (1991-03-01), Kobayashi et al.
patent: 5747049 (1998-05-01), Tominaga
Nanba Tomiyuki
Ogawa Katsuki
Takata Sadaki
Yoshino Koji
Benston, Jr. William E.
Page Thurman K.
Shiseido Company Ltd.
LandOfFree
Powder coated with sparingly soluble ultraviolet absorber does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Powder coated with sparingly soluble ultraviolet absorber, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Powder coated with sparingly soluble ultraviolet absorber will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1782068