Drug – bio-affecting and body treating compositions – Live hair or scalp treating compositions – Shaving preparation
Reexamination Certificate
2000-04-07
2001-10-23
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Live hair or scalp treating compositions
Shaving preparation
C424S070100, C514S770000, C514S783000, C514S938000
Reexamination Certificate
active
06306380
ABSTRACT:
The present invention relates to depilatory compositions in the form of an improved oil-in-water emulsion; their preparation; and their use in degrading hair keratin.
BACKGROUND OF THE INVENTION
Compositions for removing superfluous body hair are well known and are of various types. One type of composition requires initial heating before being applied to the skin in a generally molten state. It is then allowed to solidify before being removed from the skin together with unwanted hair.
Another type of depilatory composition is in the form of a cream, which can be applied to the skin at room temperature. The cream includes a substance that degrades hair keratin. Such substances tend to irritate the skin which is a problem for users with sensitive skin. Compositions with reduced irritancy have been sought.
SUMMARY OF THE INVENTION
The present invention therefore provides a depilatory composition comprising:
(a) a continuous aqueous phase;
(b) a depilatory agent; and
(c) an oil phase comprising
(i) a non-polar oil separated from the continuous aqueous phase by a bilayer phase comprising
(ii) a surfactant; and
(iii) a polar substance;
wherein the composition is substantially free from tertiary amines.
However, the present inventors do not wish to be bound by the definition of the particular structure of the composition that they believe to be formed. According to the present invention, there is further provided a depilatory composition comprising from 2% to 6% w/w of depilatory agent, from 0.2% to 20% w/w of non-polar oil, from 2% to 20% w/w of surfactant, from 0.5% to 20% w/w of polar substance and from 95.3% to 34% w/w of aqueous phase; wherein the composition is substantially free from tertiary amines.
DETAILED DISCLOSURE
The depilatory agent is a substance capable of degrading keratin and may be, for example, a sulphur compound such as potassium thioglycolate, dithioerythritol, thioglycerol, thioglycol, thioxanthine, thiosalicylcic acid, N-acetyl-L-cysteine, lipoic acid, NaHSO
3
, Li
2
S, Na
2
S, K
2
S, MgS, CaS, SrS, BaS, (NH
4
)
2
S, sodium dihydrolipoate 6,8-dithiooctanoate, sodium 6,8-dithiooctanoate, salts of hydrogen sulphide for example NaSH or KSH, thioglycolic acid, thioglycerol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomailic acid, ammonium thioglycolate, glyceryl monothioglycolate, monoethanolamine thioglycolate, monoethanolamine thioglycolic acid, diammonium dithiodiglycolate, ammonium thiolactate, monoethanolamine thiolactate, thioglycolamide, homocysteine, cysteine, glutathione, dithiothreitol, dihydrolipoic acid, 1,3-dithiopropanol, thioglycolamide, glycerylmonothioglycolate, thioglycolhydrazide, keratinase, hydrazine sulphate, hydrazine disulphate, triisocyanate, guanidine thioglycolate, hair reducing pack, calcium thioglycolate and/or cysteamine. However, the composition is preferably substantially or, more preferably, completely free from depilatory agents that destroy the thermodynamic equilibrium or the surface tension of the composition; examples of such agents include alkali metal sulphides. Preferably, the composition comprises from 2.0% to 6.0% w/w of the keratin-degrading substance in order to obtain a satisfactory depilation time of about 5 minutes.
It is preferred that the non-polar oil is in the form of droplets, although it may also be in the form of sheets. When in the form of droplets, each droplet of the non-polar oil is preferably individually surrounded by one or more than one bilayer. When in the form of sheets, each sheet of the non-polar oil is preferably separated from the adjacent sheet by one or more than one bilayer. More preferably, each bilayer, in the case where more than one is present, is itself separated by a bilayer aqueous phase comprising at least water and depilatory agent.
The non-polar oil preferably has a polarity index of from 20 to 46 mN/m, more preferably from 30 to 46 mN/m. The polarity index is a measure of the interfacial surface tension between oil and water. This term is defined and explained in Principles of Colloid and Surface Chemistry, Paul C Hiemenz (2nd edition, Marcel Dekker 1986) incorporated herein in its entirety.
Suitable non-polar oils include thick mineral oils e.g. paraffin oil, sweet almond oil, isohexane, sunflower seed oil, apricot kernel oil, and/or shea butter. The non-polar oil and the polar substance are preferably miscible i.e. a mixture containing 50% of each should exhibit no phase separation. When the non-polar oil is in the form of droplets, these preferably have a diameter of from 0.01&mgr;, preferably from 0.1 &mgr;m, to, preferably 10 &mgr;m, more preferably 1 &mgr;m, most preferably 0.5 &mgr;m. Preferably, the composition comprises from 0.2% to 20% w/w, more preferably from 0.2% to 4%, most preferably from 0.5% to 2% w/w of the non-polar oil.
The surfactant and oils in the oil phase are preferably chosen so that the Required Hydrophilic-Lipophilic Balance (RHLB) value of the total oil phase is of the order of the Hydrophilic-Lipophilic Balance (HLB) value of the surfactant. Preferred compositions of this invention are wherein the RHLB value of the total oil phase and the HLB value of the surfactant are substantially equal. THE HLB value is a measure of the hydrophile-lipophile balance as discussed in Encyclopedia of Emulsion Technology, edited by Paul Becher (pages 217-220, volume 1 (1983), Marcel Dekker) incorporated herein by reference in its entirety. The RHLB is explained in Encyclopedia of Emulsion Technology, edited by Paul Becher (pages 353-366, volume 1 (1983), Marcel Dekker) incorporated herein by reference in its entirety.
Preferably, the RHLB value of the total oil phase and the HLB value of the surfactant are each independently from 9 to 12, more preferably from 10 to 11, especially about 10. The polar substance preferably has an RHLB value of from 7 to 16.
In general the surfactant is anionic, cationic or non-ionic. It is preferably non-ionic. Examples of suitable surfactants include ceterayl phosphate, cetearyl alcohol, cetearyl glucoside, cetostearyl alcohol and/or ceteareth 20. It is preferably present in an amount of from 2.0% to 20% w/w, more preferably from 2.0% to 10% w/w, most preferably from 3% to 8% w/w.
The polar substance preferably has a polarity index of from 2 to 15 mN/m, more preferably from 2 to 8 mN/m. The polar substance preferably is a polypropylene oxide-15 sterayl ether, such as that known under the trade designation Arlamol E of ICI Ltd., having a polarity index of about 5.2 mN/m. More preferably the polar substance is a polar oil. Other suitable polar substances are olive oil, macadamia nut oil, avocado oil, calendula oil, wheat germ oil, and/or cyclomethicone optionally admixed with polypropylene oxide-15 stearyl ether.
Preferably, the composition comprises from 0.5 to 20.0% w/w, more preferably from 0.5 to 2%, most preferably from 0.4 to 1% w/w of the polar substance.
Optionally, the composition includes an accelerator that will accelerate the keratin degradation reaction such as urea, thiourea, dimethyl isosorbide (DMI), ethoxydiglycol (Transcutol) or methyl propyl diol (MP diol). Preferably the accelerator is urea or methyl propyl diol. The composition according to the invention preferably comprises from 5% to 15% w/w, more preferably about 8% w/w of an accelerator.
It is particularly preferred for the composition further to comprise an pH regulator to assist in activating the depilatory agent. Preferably the quantity and type of pH regulator is chosen to maintain the pH of the composition at a value greater than 5, preferably greater than 7, more preferably in the range of from 8 to 13, most preferably in the range of from 12 to 12.5, especially about 12. For example, by ensuring that the pH is about 12.1 to 12.5, depilation can occur within about 5 minutes, as desired by the user, without causing undue irritation.
The pH regulator preferably is in the aqueous phase (between the oil droplets) when present. Examples of the pH regulator include arginine (especially L-arginine), silicates (e.g. sodium or potassium silicate), lime and
Desmots Sarah
Guillaume Bruno
Ledon Philippe
Pires Veronique
Fish & Richardson P.C.
Reckitt & Colman France
Spear James M.
LandOfFree
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