Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations – Aromatic acid or derivative containing
Reexamination Certificate
2000-03-23
2002-07-23
Lovering, Richard D. (Department: 1712)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
Aromatic acid or derivative containing
C106S002000, C424S070120, C424S070121, C424S070190, C508S208000, C514S937000, C516S023000
Reexamination Certificate
active
06423303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to water-in-oil emulsions containing increased amounts of an oil phase. More specifically, the invention relates to water-in-oil emulsions comprising oil and water phases and an emulsifier comprising a phthalic anhydride derivative that are stable at critical pH values. Further, it relates to oil and water emulsions containing organic sunscreens or containing organic and/or inorganic (physical) sunscreen components. It further relates to suncare/skincare compositions capable of providing a high degree of protection from the harmful effects of ultraviolet radiation, such as sunburn and sun-induced premature aging.
2. Description of the Related Art
Water-in-oil emulsions have been employed in a wide variety of applications. Among these are polishes and waxes for hard surfaces of, for example, automobiles, shoes, and furniture. Water-in-oil emulsions are also used as antiperspirants, sunscreens, skin creams and lotions, and hair treatment compositions such as hair conditioners.
Incorporation of increased amounts of oil, and especially silicone oil, leads to difficulty in preparing stable water-in-oil formulations. It is particularly difficult to formulate stable water-in-oil emulsions having in excess of 50% by weight silicone oil. Thus, formulations of water-in-oil systems with oils such as silicones requires the use of an emulsification system capable of providing the requisite emulsion stability.
U.S. Pat. No. 5,188,823 discloses water-in-oil antiperspirant formulations comprising silicone oils, copolyols, phthalamic acids and/or ammonium phthalamates, and aluminum and zirconium antiperspirant salts. Water-in-oil formulations containing at most about 33% cyclomethiones are disclosed having viscosities ranging from about 2,700 to 14,000 cps. The pH of these water-in-oil formulations is from about 3.5 to 4.5.
U.S. Pat. No. 5,015,415 teaches conditioning shampoos comprising phthalamic acids and/or ammonium phthalamates and silicone oils. Shampoo formulations are disclosed with no more than 0.50% silicone oil. These formulations are taught to be stable at pH values between 3 and 9.
Canadian Patent Application 2,056,859 discloses hair treatment compositions comprising a water-in-oil emulsion, wherein the water phase constitutes 40-95% by weight of the composition and the oil phase 5-60% by weight of the composition, wherein the oil phase comprises a silicone material having a viscosity of 10
4
to 10
9
mPas at 25° C.
SUMMARY OF THE INVENTION
It has been unexpectedly discovered that stable water-in-oil emulsions can be prepared to contain in excess of about 50% by weight oil when the emulsion is formulated with a specific emulsification system and the resulting emulsion is at a specific critical pH. The emulsions of the invention can be prepared to contain any amount of an oil up to about 65% by weight of the formulation.
The water-in-oil emulsions encompassed by the invention comprise:
(a) water;
(b) from about 10 to 65% by weight of an oil; and
(c) an emulsification system comprising a polysiloxane polyalkyl polyether copolymer and a phthalic anhydride derivative, the emulsification system substantially permanently maintaining the water and oil as an emulsion, and the emulsification system being substantially free from aluminum and zirconium salts, the emulsion being at a pH of from about 5-10.
The invention encompasses stable water-in-oil emulsions having viscosities in the range of from about at least 1000, and preferably from about 1500 to 10
6
cps. The invention also encompasses such emulsions that are pastes, i.e., emulsions that are typically not a pourable liquid at ambient temperature.
The invention further provides water-in-oil emulsions containing a sunscreen component or agent. In these sunscreen compositions, the sunscreen agent may be a component of the water phase or the oil phase of the emulsion. Where the sunscreen agent is a component of the water phase, the sunscreen agent is preferably soluble in the water phase. Similarly, where the sunscreen agent is a component of the oil phase, the sunscreen agent is preferably soluble in the oil phase. Alternatively, the sunscreen agent may be a physical sunscreen agent simply dispersed within the emulsion.
DETAILED DESCRIPTION OF THE INVENTION
Water-in-oil emulsions, and in particular, water-in-oil emulsions containing silicone, are difficult to prepare without separation into oil and water phases when the amount of the oil approaches 50% by weight. The present invention provides novel water-in-oil emulsions that are stable when containing more than 50% by weight of an oil phase. These emulsions employ an emulsification system comprising a specific phthalic anhydride derivative and a silicone glycol surfactant. Further, the pH of the emulsion must be within the critical range to obtain the requisite stability.
The Oil Phase
Water-in-oil compositions of the invention comprise from 5-65% by weight, more preferably from 10-65% by weight, most preferably 20-60% by weight of an oil phase. The oil phase may comprise any oily material that is immisible with water. Suitable oily materials are those having viscosities from about 0.1 to 10,000,000 cps. In preferred embodiments of the invention, the oily material is a silicone oil material.
The silicone material for use in compositions of the invention can be any silicone material of the required viscosity. For example, polyalkyl siloxanes, polyalkylaryl siloxanes, aminofunctional silicones, polydiorganosiloxanes or mixtures thereof may be used.
Silicone gums i.e., non volatile silicones, may be used as the silicone materials. For the purpose of the present invention, the term silicone gum denotes polydiorganosiloxanes having a molecular weight of 200,000 to 2,000,000. Examples of suitable silicone gums are for example described in U.S. Pat. No. 4,152,416. Specific examples of suitable silicone gums are polydimethyl or polydiphenyl siloxane polymers.
Such silicone materials for use in the compositions of the invention have a viscosity of 10
4
to 10
9
mpa.s at 25° C., more preferably from 5×10
4
to 5×10
8
, most preferably from 10
5
to 5×10
7
mpa.s. A suitable method for measuring the viscosity is by means of a glass capillary viscometer (of Dow Corning CTM 0004), or by a Brookfields synchrolectric viscometer (cf Dow Corning CTM 0050).
In certain embodiments of the invention, the oil phases of compositions also comprise a carrier or diluent material for the high viscosity, non-volatile silicone material. Often, high viscosity silicone materials are supplied as a dispersion in a carrier or diluent material, for example as a 5-25% by weight dispersion of the high viscosity silicone in cyclomethicone, linear dimethicone and/or isoparaffin. These dispersions may advantageously be used in the oil phase of the hair treatment products of the invention. Alternatively or additionally the oil phase may comprise further diluents such as for example low viscosity silicones (having a viscosity of say between 0.1 to 1,000 mpa.s, more preferably 0.5 to 500 mPa.s most preferably 0.65-100), liquid paraffins or methicones and other solvents such as C
10
to C
12
isoparaffins such as Isopar L (Esso), polyisobutene such as polysynlane (Nippon Oils and Fats), squalane such as Squalene (J. G. Marthens), branched chain hydrocarbons e.g., Permethyl 99A (Presperse), branched chain light paraffin oils such as Lytol (Witco) or WM1 (BP), mineral oil such as Marchol 82 (Esso) or Carnation Oil (Witco), long chain alkyl alkanoic esters such as decyl oleate (e.g., Cetiol V ex Henkel), isopropyl myristate (e.g., Estol 1514 ex Unichema) and glyceryl tri(2-ethyl hexanoate) e.g., Myritol CTEG ex Henkel).
In preferred embodiments, the silicone oil will comprise a cyclomethicone or dimethicone. Generally such silicones may be represented by the formula:
werein R is a 1 to 3 carbon alkyl group, n is a number from 3 to 10, preferably from 3 to 7, and the unsatisfied valences on the oxygen and silicon atoms at the
Ryklin Irma
Sajic Branko
Lovering Richard D.
McDonnell & Boehnen Hulbert & Berghoff
Stepan Company
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