Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations – Aromatic acid or derivative containing
Reexamination Certificate
2000-03-10
2003-06-10
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
Aromatic acid or derivative containing
C424S059000, C424S070900, C424S070190, C424S070220, C424S400000, C424S401000, C510S119000, C510S130000, C510S137000, C510S141000, C510S158000, C510S159000
Reexamination Certificate
active
06576228
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to personal wash compositions which deposit high levels of sunscreen (SPF >2) while maintaining good lather (i.e., suffer minimal lather degradation over time relative to compositions with more “oily” sunscreens). Enhanced deposition is found from both bar and liquid compositions and is based on the solubility or non-solubility of the sunscreen used.
BACKGROUND OF THE INVENTION
It is a difficult task to deposit significant levels of sunscreen from skin cleansers. Moreover, most sunscreens severely defoam the cleanser composition. Therefore, previous attempts to deliver sunscreen from cleansers resulted in cleanser having low levels of protection (i.e., SPF <2); which had unsatisfactory user properties (e.g., low lather); and which were expensive to make (because of high levels of sunscreen required to obtain effective protection).
One reason deposition has been so difficult to achieve is that most of sunscreens used are either water insoluble oils or insoluble fine solid particles (e.g., ZnO, TiO
2
). Such sunscreens are generally dispersed into dilute suspensions by surfactants present in the cleanser. As a result, and without wishing to be bound by theory, it is believed that most of the sunscreen will remain suspended, the suspended sunscreen will be removed when skin is rinsed, and little will be left to deposit on the skin. Further, dispersions of the sunscreens into the wash liquid tends to defoam the liquor. In addition, incorporation of oily sunscreen in bars also generally increases softness, stickiness and mush.
Unexpectedly, applicants have found a novel class of sunscreens which can be delivered and provide superior sun protection. These sunscreens can be deposited even in presence of anionic surfactants. Unlike most sunscreens, these are much more soluble in water than the usual “oily” sunscreen and provide measurable sun protection even at low levels of addition (e.g., 0.1-15%, preferably 0.5 to 12%, more preferably 1.0 to 10% by wt.). Moreover, since they are more soluble in water, they do not defoam cleanser during wash process.
More specifically, applicants have found specific sunscreen agents which are organic molecules absorbing light in the UV range. These sunscreens are water-soluble UV absorbers (greater than or equal to 0.1% preferably greater than 0.5% water solubility on a weight to weight basis at neutral pH). The sunscreens include a functional group that is anionic or at least part of the sunscreen becomes anionic (e.g., anionic functional group incorporated at sufficiently high pH) at suitable pH (e.g., pH ≧3, preferably greater than 4, preferably 4 to 10) and the sunscreens are water soluble or become soluble at suitable pH (again about 3 to 10). Examples of such molecules include: phenylbenzimidazole sulphonic acid, anionic salts of said acid which form at pH of 7 and above and mixtures thereof (forming at pH between 4 and 7); ferulic acid, its anionic salts and mixtures thereof; benzophenone-4, its anionic salts and mixtures thereof; and benzophenone-9, its anionic salts and mixtures thereof. Preferably, the sunscreen agents are used in the form of their salts generally at pH 7 and above.
While not wishing to be bound by theory, these anionic organic sunscreen molecules are believed to bind to positively charged sites on proteins within the skin thereby accounting for enhanced deposition. Because molecules deposited through binding from solution cover the surface uniformly, the UV protection is also believed to be more effective than protection obtained from oily or particulate sunscreens where the deposition may be localized to small areas of skin and leave some areas unprotected. Moreover, because the agents are more soluble in water than oily components, they cause less defoaming than the oily or particulate sunscreen agents. As noted above, oily, particulate sunscreens are believed to suspend in surfactants and more readily wash off when rinsed, thereby leading to lower deposition. Oily agents also lead to mushier bars. The specific sunscreen agents of the invention avoid these problems.
Some of the organic sunscreen materials of the invention are not new. For example, WO 14053 to Cussons Int. Ltd. teaches personal wash compositions containing sunscreen agents including phenylbenzimidazole sulphonic acid (which is recited among a list of sunscreen agents which may be used (page 7).
The reference does not recognize that the sulphonic acid sunscreen agent or salts thereof provide superior sun protection relative to other sunscreens including even those used in the reference itself (see Examples 1-3 of reference). The higher water solubility also makes the sunscreens less defoaming and more soluble for personal wash products where foaming is considered a desirable attribute.
U.S. Pat. Nos. 4,933,174 and 4,701,321 by J. Bernstein (assigned to Amethyst Investment Group, Inc.) teaches a liquid PW composition, which comprises nonionic and amphoteric surfactants, and sunscreen materials including aminobenzoic acid, the esters of an aminobenzoic acid, homosalate, 2-hydroxy-4-methoxylbenzophenone (oxybenzone) or 2-ethoxyethyl p-methoxycinnamate (cinoxate). Nonionic and amphoteric surfactants instead of anionic surfactants are used to enhance the deposition of sunscreen agents. Repeated washing and bathing with the compositions leaves a long-lasting layer of sunscreens in the stratum corneum of the skin. The reference fails to recognize that specific anionic sunscreens (e.g., anionic salts) of the invention, particularly when used in systems comprising anionic surfactants, deposit better than other sunscreens.
The noted U.S. patents also do not specifically include phenylbenzimidazole sulphonic acid, benzophenone-4 or any of the other materials suitable for our invention as candidates for the sunscreen agents claimed. These patents further require that formulations contain only nonionic or amphoteric surfactant and further requires that the compositions be used repeatedly over many weeks to achieve the claimed effects.
BRIEF SUMMARY OF THE INVENTION
Unexpectedly, applicants have found that when specific sunscreens and/or their salts are used in personal wash compositions, they are more water soluble than many oily particulate sunscreens normally used (e.g., “normal” oils having solubility of less than 0.1% wt. by wt. water compared to more soluble “salts” of subject invention); they provide enhanced sun protection factor or SPF (e.g. SPF greater than 2, to about 25, preferably greater than 3 to 20, more preferably from about 4 to 15); and the sunscreen does not depress foaming (e.g., foaming does not depress over time compared with more oily components whose lather does depress more quickly over time).
Generally, using the sunscreens of invention, foaming does not depress more than about 50%, preferably more than 30%, preferably more than about 25% over 30 minutes time using test as defined in examples.
More specifically, the present invention provides a personal wash composition, particularly personal wash compositions which may be in bar or liquid form. In one embodiment the compositions are bars comprising:
(1) 20% to 85% by wt of first anionic surfactant which may be fatty acid soap or a synthetic anionic;
(2) 0-25%, preferably 1-20% second surfactant selected from the group consisting of second anionic surfactant (different from first), nonionic, amphoteric, cationic and mixture thereof;
(3) 0-15% free fatty acid;
(4) 0-20% water soluble structurant (e.g., polyalkylene glycol, EO-PO copolymers);
(5) 0 to 40%, preferably 0-35% alkanoate (e.g., glycerol monostearate) having chain length of C
12
to C
24
; and
(6) 0.1 to 10% of a sunscreen agent, anionic salt (e.g., functional group attached to sunscreen agent which, in solution, yields negative charge such as, for example, sulfates, sulfonates, carboxylates, phosphates, phosphonates, etc.), or mixtures thereof (at least some portion of the sunscreen must be in its salt form; however, this is inherently accomplished by specifying minimum pH value
Crookham Harry
He Mengtao
Khan-Lodhi Abid
Lang David John
Koatz Ronald A.
Lamm Marina
Unilever Home & Personal Care USA , division of Conopco, Inc.
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