GB2336535A - Depilatory Compositions - Google Patents

Abstract

A depilatory composition is prepared by heating an aqueous solution of sucrose (60-90% by weight) in the presence of citric or hydrochloric acid and optionally a polyethylenimine catalyst until it is substantially free of sucrose and then adding a natural wax or resin. Alternatively the wax or resin is added before the heating process. The resulting, water soluble compostions, which do not require reheating before application, are spreadable at room temperature, and can be washed off if misapplied.

Description

2336535 -I- COMPOSITIONS This invention relates to an epilatory

composition, its manufacture and use.

Epilatory compositions formed of water-insoluble viscoelastic esters are well known and, ordinarily, include a tackifier, such as colophony, to make them sticky. In use, they are usually applied to the skin by means of a spatula at a temperature of from 401C to 550C. Strips of cotton or the like are then applied so that they adhere to the epilatory material. The strips are then pulled off to remove the epilatory material, and hair, from the skin.

Some epilatory compositions have previously been disclosed, which are based on heating sugar(s) with acid (such as citric acid), for example, in British patent specification nos. GB 901624; GB 1242083; GB 2231494A and GB 2157951A. However, these compositions, once cooled and set, need to be reheated before use. At least the latter two disclosures specify sucrose as being a preferred choice of sugar for the composition. The heating period during manufacture of the composition is generally in excess of about 1 to 11. hours for such compositions.

There is therefore a need for a so-called 'cold' epilatory composition (i.e. one which can be applied at room temperature without reheating), which is relatively quick to manufacture and is water- soluble.

It has now surprisingly been found that a composition based on heating sugar(s) with acid in the presence of resin and/or natural waxes, which composition is substantially free of sucrose, is both relatively quick to manufacture and is spreadable/usable at room or ambient temperatures.

Accordingly, the present invention provides an epilatory composition which is substantially free of sucrose and which comprises the acid hydrolysis product produced from the reaction of (a) (b) (c) from about 60 to about 90% w/w of sucrose; from about 7 to about 35% w/w water; from about 1 to about 5% w/w of an acid for hydrolysing the sucrose; and (d) from about 0.1 to about 10% w/w resin and/or natural waxes, preferably in the form of micrometric droplets; optionally in association with one or more excipients.

The natural wax and/or resin droplets are incorporated to reduce residue in the range of from 0.1 to 10% w/w. Preferably, 1 to 5% w/w micrometric droplets of a natural wax and/or resin are incorporated. These are droplets preferably having a diameter in the range of from 0.051-5p, more preferably, 0.051-0.5p (measured by photon correlation spectroscopy). Examples include colophony, beeswax, candelilla wax, carnauba wax, ozokerite, gum arabic or the like.

There is also preferably incorporated a surfactant for the droplets, more preferably up to 5% w/w of a surfactant such as a fatty acid salt, for example sodium lauryl sulphate or the like.

In accordance with a preferred embodiment of the present invention, the epilatory composition comprises the acid hydrolysis product produced from the reaction of (a) from about 80 to about 90% w/w of sucrose; (b) from about 8 to about 20% w/w water; (c) from about 3 to about 5% w/w of an acid for hydrolysing the sucrose; and (d) from about 1 to about 5% w/w microdroplets of resin and/or natural waxes, preferably having a diameter in the range of 0.05p - 5p; optionally in association with one or more excipients, such as one or more of (i) up to about 5% w/w of polyethylene imine; (ii) up to about 10% w/w tackifier; (iii) q.v. pH adjuster to adjust pH of the final composition to about 7; (iv) up to 5% w/w cross-linked polymer to is reduce residue on peeling; (v) up to 5% w/w hydrogenbonding polymer; (vi) up to 5% w/w polymer having a shear thinning effect at room temperature and a glass transition temperature in the range 20 of from 280C to 450C; (vii) up to 5% w/w thermochromic indicator; and/or (viii)up to 5% w/w surfactant.

Preferably, the hydrolysis product has a viscosity in the range of from 100 to 1500 poise at 331C, measured by ARES at a shear rate of 100 s-' ' More preferably, it has elastic (G') and viscous (G") moduli which satisfy the following parameters at 300C and at a strain of from 0.05 to 10%:

(i) 106 <G"<108 Pa at a frequency of 5000 rad/s (ii) W > G' at a frequency of 5000 rad/s (iii) G" > G' at a frequency of 1 rad/s (iv) 10 < G" < 10' Pa at a frequency of 1 rad/s.

The storage (elastic) modulus G' corresponds to the energy which can be stored and released by the bulk material and the loss (viscous) modulus W corresponds to the energy dissipated by the bulk material due to friction between its macromolecules when it is deformed.

G' = g. cos 6 7.

and = g. sin 3 Y.

wherein a.is the stress amplitude and y. is the strain amplitude.

The measurements are based on studies carried out into the rheology of visco-elastic materials in order to obtain a better understanding of their adhesive behaviour and their suitability as epilatory materials. These studies involved subjecting the materials to dynamic investigations in which a sinusoidal strain at defined frequencies was applied to the materials and the resulting output force was measured. In these studies, two strain control rheometers were used viz. an RSA (Rheometrics Solid Analyser) rheometer based on shear sandwich geometry and an ARES rheometer based on parallel plate geometry of 25mm in diameter. Both devices are commercially -5 available from the company Rheometrics. The output force was found to include an in-phase elastic component (referred to as the storage or elastic modulus G') and an out-of-phase viscous component (referred to as the viscous or loss modulus W). The output force (a) can be expressed as follows: a = a. sin (wt + 8) = a. cos3 sin wt + a. sin3 coswt where w is the frequency, t is the time, and 3 is the out of phase coefficient.

A strain of from 0.05 to 10% corresponds to the linear domain of the material. G' needs to be lower than W in order to prevent the material cracking and to ensure that the material has strong adhesion at the is material/hair interface. The values of GF and G" at low frequency oscillation are a measure of how readily the material wets the hairs. Low frequency oscillation is a long time process and corresponds to the time when the material is being applied to the skin or is at rest. The lower the values of G' and W at this low frequency, the better the material wets the hairs. Thus the hairs become well embedded in the material in a very short time (i.e. the time needed for spreading the material on the skin).

By ensuring that the epilatory composition satisfies the above parameters, it can be readily spread on the skin at body temperature, yet it is very efficient at removing hairs from the skin and, surprisingly, the user experiences less pain.

The values of G' and W preferred in accordance with the invention are obtained by suitable control of the hydrolysis step and/or by suitable control of the amount and nature of additional components included in the material.

The acidic hydrolysis of the sucrose may be carried out by admixing sucrose and a suitable acid (such as hydrochloric acid or citric acid) with water, and preferably also with polyethene imine, and heating the mixture to a temperature of at least 11CC. The particular acid and quantity used are chosen such that the pH of the mixture is in the range of from about 0.5 to about 4. The microdroplets of resin and/or natural waxes and, optionally, the other ingredients, as appropriate, may then be added to the mixture after the hydrolysis stage.

During the course of the hydrolysis reaction, the sucrose (saccharose) is converted into a mixture of fructose, glucose and "Maillard" derivatives (which are the.result of molecular cracking and recombination of small molecules in Maillard reactions). The hydrolysis reaction should be carried out to such an extent that the product is substantially free of sucrose (i.e. contains no more than 2% of sucrose). The Maillard derivatives act as colouring agents and it is particularly preferred for the hydrolysis reaction to be carried out until such time as the product is yellowish/brownish in colour and has a colour index of about 0. 5 to 1.32 (as determined by absorption at 287 nm for sugar sample concentrations of 1 gram per litre with water as reference using a quartz cell having an optical path of 1 cm). All the products of the hydrolysis reaction are water-soluble.

Preferably, the hydrolysis product includes from 15 to 32% by weight (preferably from 21 to 26%) of fructose and from 31 to 45% by weight (preferably from 36 to 39%) of glucose, with the remainder being Maillard derivatives, as determined by HPLC.

Preferably, from about 0.1 to about 5% w/w polyethylene imine is added to catalyse the hydrolysis reaction. The polyethylene imine may be that sold by BASF under the trade names Lupasol PS or Lupasol WF.

Without the catalyst, the reaction time will be from about 30 to about 60 minutes (but may be as long as 3 hours) and the maximum reaction temperature will be about 1350C. With polyethylene imine, however, the time for hydrolysis of a similar-sized batch is reduced to from about 5 to about 30 minutes. For is example, in the absence of the catalyst, at 1100C, the hydrolysis may take about 30 minutes or more per kilogram, but in the presence of the polyethylene imine, it takes only about 5 to 10 minutes per kilogram.

In the compositions of the present invention, the catalyst for the hydrolysis reaction preferably remains intact in the product of the reaction.

Therefore, the present invention further provides an epilatory composition comprising (a) from about 15% to about 32% w/w fructose; (b) from about 31% to about 45% w/w glucose; (c) from about 0.1% to about 10% w/w micrometric droplets of a natural wax and/or resin; (d) no more than 2% w/w sucrose; (e) water, q.s. to 100% w/w; and optionally from about 0.1% to about 5% w/w polyethylene imine, optionally in association with one or more additional excipients.

The compositions of the present invention optionally further comprise a tackifier, which also provides elasticity to the final material. Examples of tackifiers which may be used are the triethyleneglycol ester of colophony (which ester is a tacky, water-dispersible resin), and/or, more preferably, polyethylenimine. The tackifier increases the peeling efficacy of the composition at low viscosity, affording the epilatory composition high spreadability. It may be present in the range of from 0 to about 10% w/w, preferably from about 0.1 to about 10% W/W.

Depending on the amount of acid used and the other ingredients present, a pH adjuster may be included to adjust the pH of the final composition to about neutral. For example, the polyethylene imine may itself perform this function.

The epilatory composition of the invention may also include up to 5% w/w of a cross-linked polymer that reduces residue on peeling. Examples include a copolymer of t-butyl acrylate, ethyl acrylate and methacrylic acrylate (such as that known as Luvimer 10OP); a copolymer of an acrylate and acrylamide (such as that known as Ultrastrong of BASF); the water-rinsable modified rosin ester known as Cerepil R186 from the Barlocher company, a copolymer of sodium acrylate and dimethyldiallyl ammonium chloride (such as that known as Merquat); and a copolymer of hydroxyethyl cellulose and dimethyl diallyl ammonium chloride (such as that known as Celquat).

The epilatory composition of the invention may also include up to 5% w/w of a polymer capable of forming hydrogen bonds with the water in the composition. Examples include glycerol; polyethylene glycol (preferably having a molecular weight of not more than 600); polyvinylpyrrolidone (such as Luviskol from BASF or PVP K30 and PVP K90 from ISP); and crosslinked acrylic polymers (such as the carbomer Ultrez 10 from Goodrich).

The presence of polyethylene glycol is particularly useful to improve even further the spreadability of the material. However, other water- soluble polymers having a glass transition temperature of from 281C to 450C (preferably from 300C to 370C) and a shear thinning affect at room temperature may be used for this purpose. In this case, the polymer should be such as to be in its glassy state at the epilation frequency (> 5000 rad/s) and its rigidity should be of the same order as that of the acidic hydrolysis product.

If desired, the composition may further include a thermochromic substance so that, after it has been applied to the skin, it changes colour as it heats up to body temperature. In this way it can be ascertained that the material is ready to be stripped off the skin.

Therefore, the present invention further provides an epilatory composition comprising (a) from about 15% to about 32% w/w fructose; is (b) from about 31% to about 45% w/w glucose; (c) from about 0.1% to about 10% w/w resin and/or natural waxes, preferably in the form of micrometric droplets; (d) no more than 2% w/w sucrose; and (e) water, q.s. to 100% w/w; optionally in association with one or more excipients, such as one or more of (i) up to about 10% tackifier; (ii) q.v. pH adjuster to adjust pH of the final composition to about 7; up to 5% w/w cross-linked polymer to reduce residue on peeling; up to 5% w/w hydrogen-bonding polymer; up to 5% w/w polymer having a shear thinning effect at room temperature and a glass transition temperature in the range of from 280C to 45OC; up to 5% w/w thermochromic indicator; up to 5% w/w polyethylene imine and/or up to 5% w/w surfactant.

(iii) (vi) (vi i) (viii) When carrying out the hydrolysis reaction, it is preferred initially to mix some of the water and the acid. Thereafter, the mixture is agitated with the sucrose and the remainder of the water, the polyethylene imine is preferably added, and the mixture heated to temperature. The resin and/or natural wax and other ingredients as appropriate may then be added to the mixture as it is cooling down to room temperature after the hydrolysis stage.

The epilatory composition in accordance with the present invention is soluble in water at room temperature and has very altered rheological properties on flowing, spreading and peeling.

The epilatory composition of the present invention may be mechanically worked so that it is manually mouldable at room temperature, applied without the use of a spatula and removed from the skin without the use of strips. The mechanical working of the hydrolysis product may be effected using a kneading or malaxing machine.

The following Example illustrates the invention.

Example 1 is 14.38% w/w of water, 0.46% w/w of 50% HCl and 85.16% w/w of sucrose were heated to a temperature of at least 1100C to hydrolyse the sucrose until the product was substantially free of sucrose. 5.0% w/w colophony (1 micron droplets); 2.0% w/w Beeswax (1 micron droplets) (Cerabel 560 from Barlocher) and 0.2% w/w sodium lauryl sulphate were then added to the mixture.

The final product was water-soluble and could be applied to the skin at room temperature by means of a spatula. When subsequently stripped from the skin, it removed hairs from the skin.

Claims (13)

1. CIAIMS

   An epilatory composition which is substantially free of sucrose and which comprises the acid hydrolysis product produced from the reaction of (a) from about 60 to about 90% w/w of sucrose (b) from about 7 to about 35% w/w water; (c) from about 1 to about 5% w/w of an acid for hydrolysing the sucrose; and (d) from about 0.1 to about 10% resin and/or natural waxes, preferably in the form of micrometric droplets; optionally in association with one or more excipients.

   is
2. 2. An epilatory composition according to claim 1, comprising (a) from about 15% to about 32% w/w fructose; (b) from about 31% to about 45% w/w glucose; (c) from about 0.1% to about 10% w/w resin and/or natural waxes; (d) no more than 2% w/w sucrose; and (e) water, q.s. to 100% w/w; optionally in association with one or more excipients.
3. 3. An epilatory composition which is soluble in water at room temperature, which composition comprises the acid hydrolysis product of sucrose and has a viscosity of from 100 to 1500 poise, at 33'C and a shear of 100 s', and values of G' and W' satisfying the following relationships at 3VC and at a strain of from 0.05 to 10%:

   (v) (vi) (vi i) (viii (i) 106 <G-<108 Pa at a frequency of 5000 rad/s (ii) G" > G' at a frequency of 5000 rad/s (iii)G" > G' at a frequency of 1 rad/s (iv) 10 < T.' < 10' Pa at a frequency of 1 rad/s wherein T is the storage modulus and G" is the loss modulus of the composition.
4. 4. A composition as claimed in any of claims 1 to 3, comprising one or more excipients selected from (i) up to about 5% w/w of polyethylene imine; (ii) up to about 10% w/w tackifier; (iii) q.v. pH adjuster to adjust pH of the final composition to about 7; (iv) up to 5% w/w crosslinked polymer to reduce residue on peeling; up to 5% w/w hydrogenbonding polymer; up to 5% w/w polymer having a shear thinning effect at room temperature and a glass transition temperature in the range of from 280C to 451C; up to 5% w/w thermochromic indicator; and/or)up to 5% w/w surfactant.
5. A composition as claimed in any preceding claim comprising glycerol and/or polyethylene glycol.
6. 6. A composition as claimed in any preceding claim comprising polyvinylpyrrolidone.
7. 7. A composition as claimed in any preceding claim comprising the resin and/or natural wax in the form of microdroplets of diameter in the range of 0.05pSp, more preferably, 0.0511-0.5p (measured by photon correlation spectroscopy).
8. A composition as claimed in any preceding claim comprising colophony, beeswax, candelilla wax, carnauba wax, ozokerite, gum arabic or the like.
9. 9. A composition as claimed in claim 7 or claim 8 comprising up to 5% w/w of a surfactant such as a fatty acid salt, for example sodium lauryl sulphate or the like.
10. 10. A process for producing an epilatory composition as claimed in any preceding claim, comprising the step of hydrolysing sucrose in an acidic medium in the presence of a catalytic amount of polyethylene imine until it is substantially free of sucrose and adding a natural wax and/or resin.
11. 11. A process according to claim 10, wherein the acid is hydrochloric acid or citric acid.
12. 12. A process according to claim 10 or claim 11, 20 wherein the hydrolysis is effected at a temperature of from 110 to 13SIC for from about to 10 minutes per kilogram of reactants.
13. 13. A process according to any of claims 10 to 12, followed by mechanical working of the hydrolysis 25 product, such as by using a kneading or malaxing machine.