Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2001-07-06
2002-08-13
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C404S060000, C404S078000, C404S078000, C404S131000, C404S131000
Reexamination Certificate
active
06432389
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to novel cosmetic/dermatological compositions for topical application, for the ultraviolet (UV)-photoprotection of the skin and/or the hair against the damaging effects of UV radiation, in particular solar radiation, and to the use of same for the aforesaid cosmetic/dermatological indications.
This invention more especially relates to topically applicable, high SPF UV-A and/or UV-B sunscreen compositions comprising particulates of a methyl methacrylate (“MMA”) crosspolymer, such compositions being well suited as “sport” products, namely, the subject formulations do not diffuse into the eyes and are dry, pleasant, less shiny and waterproof on application, as well as nontacky, nongreasy and nonwaxy to the touch.
2. Description of the Prior Art
It is well known to this art that light radiation of wavelengths of from 280 nm to 400 nm promotes tanning of the human epidermis, and that irradiation of wavelengths of from 280 to 320 nm, i.e., UV-B irradiation, causes erythema and burning of the skin which can impair the development of a natural tan; hence, such UV-B radiation must thus be screened from the skin.
It is also known to this art that UV-A radiation, of wavelengths from 320 to 400 nm, which tans the skin, also adversely affects it, in particular in the case of sensitive skin or a skin which is continually exposed to solar radiation.
UV-A rays cause, in particular, a loss in the elasticity of the skin and the appearance of wrinkles, promoting a premature aging thereof. Such irradiation promotes triggering of the erythematous reaction or enhances this reaction in certain individuals, and may even be the source of phototoxic or photoallergic reactions. Thus, it is desirable to also screen out UV-A radiation.
A wide variety of cosmetic compositions intended for the photoprotection (UV-A and/or UV-B) of human skin is known to this art.
These photoprotective/sunscreen compositions are quite often oil-in-water emulsions (namely, a cosmetically acceptable vehicle, carrier or diluent comprising an aqueous continuous dispersing phase and an oily discontinuous dispersed phase) which contains, in various concentrations, one or more standard lipophilic and/or hydrophilic organic sunscreen compounds capable of selectively absorbing harmful or deleterious UV radiation. These sunscreen compounds (and the amounts thereof) are selected as a function of the desired sun protection factor (the sun protection factor (SPF) being expressed mathematically by the ratio of the irradiation time required to attain the erythema-forming threshold with the UV screening agent to the time required to attain the erythema-forming threshold in the absence of UV screening agent).
Also, there exists an increasing demand for higher SPF suncare products. High SPFs can be attained by incorporating more sunscreens at elevated levels; however, this is not always feasible, as sunscreens add considerable cost to the formulation and high sunscreen levels can promote increased irritancy.
Corollary thereto, the dibenzoylmethane sunscreen avobenzone, for example, is a particularly attractive chemical UV-absorber/filter. But it is even more difficult to formulate high SPF sunscreen products when the formulation contains avobenzone.
Much more difficult is the formulation of high SPF avobenzone sprayable compositions. Indeed, high SPF sunscreen sprays are commercially available, but these do not contain avobenzone. Typically, high SPF values are obtained by formulating high levels of UV-B absorbing sunscreens, such as octylmethoxy cinnamate. Nonetheless, these formulations provide no protection against longer wavelength UV-A irradiation.
Too, sunscreen compositions are also know to this art that are marketed specifically as “sport” products. These must provide or deliver, for example, the following benefits: high SPF, waterproof, the product must not diffuse into the eyes, and the product must be dry on application without leaving a greasy residue on the hands.
Compare, for example, Schering-Plough's U.S. Pat. No. 5,914,102, relating to high SPF perspiration-resistant sport sunscreen compositions, an oil phase of which comprising submicron silica particles having a hydrophobic surface.
Nonetheless, the prior art high SPF sunscreen compositions suited for “sport” applications remain at least somewhat lacking in terms of total consumer acceptance, in that they continue to provide, on application, an at least somewhat objectionable tacky, greasy and/or waxy feel.
SUMMARY OF THE INVENTION
It has now unexpectedly and surprisingly been determined that formulating particulates of methyl methacrylate crosspolymers into UV-photoprotecting sunscreen compositions significantly reduces diffusion of the product and also reduces the tacky/greasy/waxy feel thereof, making it dry and pleasant on application to human skin, hair and/or scalp.
DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, methyl methacrylate crosspolymer is a synthetic copolymer of methyl methacrylate crosslinked with glycol dimethacrylate. It has the empirical formula:
(C
10
H
14
O
4
.C
5
H
8
O
2
)
x
and has been assigned Chemical Abstracts Service (CAS) No. 25777-71-3. It is also described at page 808, volume 1,
International Cosmetic Ingredient Dictionary and Handbook
(Seventh Edition, 1997), published by The Cosmetic, Toiletry, and Fragrance Association (Washington, D.C.).
One methyl methacrylate crosspolymer according to the invention is commercially available from Presperse Incorporated, Piscataway, N.J., under the trademark Ganzpearl GMP-0820. The product specifications of Ganzpearl GMP-0820 include: spherical, white fine powder having a particle size of 4-10.5 &mgr;m, preferably 4-8 &mgr;m, high oil absorption, creamy feel, good slip, specific gravity of 1.10 to 1.25, film-forming, viscosity increasing. Its loss on ignition (400° C.) is less than 0.1%, and on drying (105° C./2 hours) is less than 2.0%. The surface residual monomer content of Ganzpearl GMP-0820 is less than 20 ppm, with total residual monomer content being less than 100 ppm. Too, the crosslinking density of this very high molecular weight polymer is on the order of 43 wt % [crosslinking monomer/(crosslinking monomer+base monomer)].
Methyl methacrylate crosspolymers are also commercially available from Nihon Junyaku under the trademark Jurymer MB-1P and from Tomer under the trademark Microsphere M-305.
Characteristically, the particulates of methyl methacrylate crosspolymers according to this invention have a particle size of less than 20 &mgr;m, preferably less than 10 &mgr;m.
Consistent herewith, dry, nongreasy, nontacky and nonwaxy sunscreen formulations are provided by the addition of methyl methacrylate crosspolymer into a wide variety of sunscreen compositions, and formulated into conventional topically applicable, cosmetically/dermatologically acceptable vehicles, diluents or carriers therefor.
It too should be appreciated that formulating a sunscreen product with good aesthetics that is dry and nongreasy on application is particularly difficult if the photostabilized compositions contain on the order of 10% octocrylene, which is a viscous and sticky oil.
While not wishing to be bound to or by any particular theory, it is believed that the methyl methacrylate crosspolymer serves/acts as an oil absorber, reducing the greasiness of the final product.
Nonetheless, methyl methacrylate crosspolymer is a totally different material than those “oil absorbers” heretofore known to this art, for example the commercially available sport sunscreens indicated above containing hydrophobic silica. Indeed, various diverse materials that are claimed to be “oil absorbers” behave/function quite differently when formulated into sunscreen compositions. As one example, polymethyl methacrylate (Micropearl M100 marketed by Seppic Inc.) was otherwise formulated. It is designated an oil absorber by its supplier, but do
Hansenne Isabelle
Rick Donald W.
Dodson Shelley A.
Societe L'Oreal
LandOfFree
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