Photostable cosmetic light screening compositions

Details Photostable cosmetic light screening compositions Photostable cosmetic light screening compositions

2000-05-09

2002-01-15

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S060000, C424S078020, C424S078080, C424S400000, C424S401000

Reexamination Certificate

active

06338838

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to photostable cosmetic or pharmaceutical light screening compositions for the protection of the human epidermis or hair against ultraviolet rays of wavelengths between 280 and 400 nm (UV-A/UV-B).
More specifically, the invention relates to photostable light screening compositions containing a dibenzoylmethane UV-A screening agent and a p-methoxycinnamate UV-B screening agent wherein one of the screening agents is incorporated in a polymer latex.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,372,804 (Chesebrough-Pond) relates to cosmetic compositions having at least one light screening agent wherein the light screening agent, is carried in or on polymer latex particles. The polymer latex particles effect a good deposition of the light screening agents onto hair or skin. Specifically disclosed light screening agents include benzophenone compounds, dibenzoylmethane derivatives and cinnamate derivatives, such as 2-ethylhexyl p-methoxycinnamate (PARSOL® MCX). The polymer particles employed may be of any polymeric material that is a good film former. The polymer particles may be substantially solid or may be porous and have a particle size of about 10-1000 nm. In order to get polymers having good film forming characteristics, a low glass transition temperature in the region of the temperature of normal use of the cosmetic composition, approximately 30° C., is required.
The above mentioned U.S. patent only discloses that light screening agents can be incorporated into a latex, thereby achieving the advantage of enhanced deposition. Said U.S. patent does not address the problem of photostability, which problem is due to an interaction of 4-tert. butyl-4′-methoxydibenzoyl-methane (PARSOL® 1789) with other light screening agents under light especially with 2-ethylhexyl p-methoxycinnamate (PARSOL® MCX).
Cosmetic light screening compositions based on dibenzoyl methane derivatives as UV-A screening agent and photostabilized with 3,3-diphenylacrylate derivatives are described in the European Patent Publication EP 0 514 491 B1 and in the European Publication EP 0 780 119 A1. However, this type of stabilization does not prevent the photochemical interaction between cinnamate derivatives, such as 2-ethylhexyl p-methoxycinnamate, and dibenzoylmethane derivatives, such as 4-tert. butyl-4′-methoxydibenzoyl-methane.
SUMMARY OF THE INVENTION
It has now been found that the photostability of light screening compositions containing a dibenzoyl methane UV-A screening agent and a p-methoxycinnamate UV-B screening agent is improved if one of said light screening agents is incorporated into a polymer latex.
Accordingly, one aspect the invention is concerned with a method of photostabilizing mixtures of a dibenzoylmethane UV-A screening agent and a p-methoxycinnamate UV-B screening agent in a light screening composition, which method comprises incorporating one of said light screening agents into a polymer latex.
In still another aspect the present invention is concerned with a light screening composition containing, based on the total weight of the composition,
about 0.5 wt % to about 5 wt % of a dibenzoylmethane UV-A screening agent incorporated into a polymer latex,
about 1 wt % to about 15 wt % of a p-methoxycinnamate UV-B screening agent; and,
optionally, other conventional UV-A and UV-B screening agents.
In yet another aspect the present invention is concerned with a light screening composition containing, based on the total weight of the composition,
about 1 wt % to about 15 wt % of p-methoxycinnamate UV-B screening agent incorporated into a polymer latex;
about 0.5 wt % to about 5 wt % of a dibenzoylmethane UV-A screening agent; and,
optionally, other conventional UV-A and UV-B screening agents.
DETAILED DESCRIPTION OF THE INVENTION
As far as the dibenzoylmethane UV-A screening agent is concerned, the preferred compound is 4-tert. butyl-4′-methoxydibenzoyl-methane, which is sold under the tradename PARSOL® 1789.
Other suitable compounds of this particular type include: 2-methyldibenzoyl-methane, 4-methyldibenzoyl-methane, 4-isopropyldibenzoyl-methane, 4-tert. butyldibenzoyl-methane, 2,4-dimethyldibenzoyl-methane, 2,5-dimethyldibenzoyl-methane, 4,4′-diisopropyldibenzoyl-methane, 2-methyl-5-isopropyl-4′-methoxydibenzoyl-methane, 2-methyl-5-tert. butyl-4′-methoxydibenzoyl-methane, 2,4-dimethyl-4′-methoxydibenzoyl-methane, and 2,6-dimethyl-4-tert. butyl-4′-methoxydibenzoyl-methane.
As used herein the term “p-methoxycinnamate UV-B screening agent” refers to compounds such as 2-ethoxyethyl p-methoxycinnamate, 2-ethylhexyl (or pentyl) p-methoxy-cinnamate, potassium p-methoxycinnamate, sodium p-methoxycinnamate, ammonium p-methoxycinnamate, salts of primary, secondary or tertiary amines of p-methoxycinnamic acid like mono-, di-, tri-ethanol amine salt and the like. Preferred is 2-ethylhexyl p-methoxycinnamate, sold under the tradename PARSOL® MCX.
As used herein, the term “polymer latex” refers to a stable colloidal dispersion of polymer particles in an aqueous or an aqueous based phase including polymers and/or copolymers of unifunctional monomers and/or multifunctional monomers. The dibenzoylmethane UV-A screening agent or the p-methoxycinnamate UV-B screening agent is incorporated into the polymer latex.
As used herein the term “unifunctional monomers” includes C
1
-C
6
-alkyl (meth)acrylate, acrylic acid, methacrylic acid, styrene, ethylene, propylene, butylene, butadiene, isoprene, isobornyl methacrylate (IBOMA), trifluoroethyl methacrylate, perfluoralkyl 2-ethylacrylate and the like.
As used herein the term “multifunctional monomers” includes allyl methacrylate (ALMA), ethyleneglycol dimethacrylate (EGDMA) and the like.
A preferred polymer latex is a stable colloidal dispersion of copolymer particles of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allyl methacrylate (ALMA) and ethyleneglycol dimethacrylate (EGDMA) or containing isobornyl methacrylate (IBOMA) crosslinked with allyl methacrylate (ALMA).
The polymer particles can have a matrix structure within which the dibenzoyl-methane UV-A screening agent or the p-methoxycinnamate UV-B screening agent is homogeneously distributed over the whole volume of the polymer particles, or the polymer particles can have a reservoir structure.
As used herein the term “reservoir structure” refers to particles having a polymer core surrounded by a polymer shell, wherein the core contains the dibenzoylmethane UV-A screening agent or the p-methoxycinnamate UV-B screening agent.
In one aspect, the core and the shell portions of the core/shell polymer particles may have the same chemical composition with regard to the monomers used. Suitable monomers used include unifunctional and multifunctional monomers as listed above.
In another aspect, the core and shell portions of the core/shell polymer particles may differ in their chemical composition. In this case, the monomers used in the core portion of the core/shell particles may also include the unifunctional and multifunctional monomers as listed above. The monomers used in the shell portion of the core/shell particles suitably include hydrophilic or fluorinated monomers.
Preferred core/shell particles include particles wherein
a) the core consists of a polymer and/or a copolymer of methyl methacrylate (MMA) and acrylic acid (AA) crosslinked with allyl methacrylate (ALMA) and ethyleneglycol dimethacrylate (EGDMA) or containing isobornyl methacrylate (IBOMA) crosslinked with allyl methacrylate (ALMA); and
b) the shell consists of hydrophilic polymer or fluorinated polymer chains.
Hydrophilic polymer shells are obtainable by copolymerization of monomers containing carboxylic acid groups such as acrylic acid, methacrylic acid, monomers bearing hydroxyl groups, such as, e.g., hydroxy-C
1
-C
6
-alkyl (meth)acrylate, (HEMA) and acrylamides (AAm). A suitable hydroxy-C
1
-C
6
-alkyl (meth)acrylate is hydroxyethyl methacrylate.
Fluorinated polymer shells are obtainable by copolymerization of acrylic esters, such as,

Affiliated with

Also associated with

Rating

Photostable cosmetic light screening compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Photostable cosmetic light screening compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photostable cosmetic light screening compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2839810