EP1482819B1 - Peeling strip for epilation with epilation wax - Google Patents

Description

The present invention relates to a tear strip used in an epilation wax removal operation, more particularly to remove a layer of wax deposited in the molten state on the skin.

The methods known in the state of the art for performing hair removal with depilatory wax consist mainly in coating a skin zone with a depilatory wax applied in the liquid or pasty state on the latter in order to imprison the hairs, wait for a while for the wax to harden and then pull the hairs off at the same time as the wax strip.

The depilatory wax compositions used are generally applied hot to the skin. For the application of the wax on the skin is used either wax-coated strips that are warmed beforehand, or applicators of a layer of wax that is then removed with or without support tape.

A depilatory band is described in the document US 1,620,539 , the band being constituted by a flexible support, in particular a band of gauze on which is deposited a layer of wax depilatory. The strip is heated before its application on the skin, it is then deposited on the skin and finally removed, after cooling, by tearing with the hair to which it had adhered. The heating temperature of such a band must be strictly controlled to avoid burns when applied to the skin. Moreover, the use of such strips is not very practical, because it is necessary to use different types of strips for different areas of skin to be treated.

A wax depilatory device is described in the patent application FR 2,706,261 in the name of the plaintiff. This apparatus comprises a housing intended to be held by hand, enclosing a reservoir of product to be applied in thermal relation with heating means, and an applicator roll arranged in the vicinity of an outlet of the tank and for applying the heated product, especially the wax depilatory on the skin. The depilatory wax is a self-supporting rosin-type wax which is heated, then applied in a uniform thickness band on the skin and once pulled off the hardened wax by pulling on the wax strip in the opposite direction to that of the removal. . Operating to satisfaction, it was nevertheless noticed that the tearing was long enough, because it was necessary to wait until the tape deposited on the skin hardens, it was quite difficult to grasp the end of the tape in order tearing, and that the latter can even stick to the fingers of the user.

It is also known from the state of the art another type of apparatus and hair removal technique consisting in the simultaneous heating of a quantity of wax stored in the reservoir of an apparatus, followed by the application, in particular with a roller applicator a layer of wax on the skin and removal of the wax using a tear strip. The document FR 2 520 601 describes such a device and a hair removal technique using it. The band applied by the roll is subsequently removed by affixing it over a strip of tissue which is torn off with the trapped hairs once the wax has cooled. With such an apparatus it has been found that the quality of the epilation depends very much on the viscosity of the wax which is in turn a function of the heating temperature and is very sensitive to the ambient temperature, or even to the temperature of the wax. the surface of the skin of the user.

An improved tear strip is described in the document FR 2 802 067 in the name of the applicant where a tear strip is coated with a thermochromic product to control the quality of the contact between the tear strip and the depilatory composition. However, such a tear strip testifies to the quality of the contact between the tear strip and the wax layer, and not the quality of the applied wax layer.

The quality and effectiveness of hair removal depends mainly on the quality of the wax layer applied to the skin. Thus, to have a uniform and thin layer to reduce the risk of burns on the skin, the depilatory composition must be very fluid. Moreover, for the epilatory composition to adhere well to the depilatory hairs, it is necessary that its viscosity is greater than during the deposition in a thin layer.

The object of the invention is to remedy at least in part the aforementioned drawbacks and to propose a tear strip which makes it possible to obtain a good compromise between the thickness and the uniformity of the layer of wax applied on the one hand and its adhesion to the hairs on the other hand.

Another object of the invention is to allow a hair removal operation that is effective, while reducing the pain felt when pulling the hair.

A further object of the invention is an easy-to-industrialize tear tape for a lower manufacturing cost.

These objects are achieved with a tear strip intended to be applied to a skin area covered with a layer of depilatory wax, the strip comprising a support made of a flexible material, since said support contains a material with a change of a phase having a transition temperature lower than that of applying the depilatory wax to the skin where said phase change material is charged in calories by contact with the wax layer.

The term "tear strip holder" includes a piece of fabric, nonwoven material, paper, cellophane, plastic film or any other relatively thin sheet or plate material on which a composition adheres. type of wax depilatory. The support may have a rectangular shape or any other shape that adapts to that of the area to be depilated. The tear strip is intended to be applied to the skin area coated with said composition and then removed, with the bristles embraced, pulling abruptly on one end of the strip.

By phase change material is meant a material which has the ability to change state, reversibly, within a certain range of temperatures: from the solid state to the liquid state or vice versa from liquid to solid. The energy required to change state is absorbed from the surrounding environment and is used to cross the barrier between the two states. The measured temperature of the material during its phase change is constant until the phase change is complete, the heat flow through such material is delayed during the heating and also the cooling when the phase change takes place .

By transition temperature of the phase-change material, it is understood in the context of the invention, the melting temperature of said material or the temperature corresponding to the solid-liquid transition. The upper limit of the application temperature of the depilatory wax on the skin is determined by the temperature of the threshold of pain caused by heat, which is about 45 ° C.

The tear tape support is applied to a skin area covered with a warmed epilated wax composition applied thinly and evenly to the skin. The heat of the wax layer is transmitted by conduction to the web support which is pressed against the skin to obtain good contact with the wax layer applied thereto. The phase change material of the tape carrier then charges heat by direct contact with the wax layer, which heat is stored by the material until it reaches its melting temperature. At this time, the constant temperature melting of the phase change material takes place. A very large amount of heat is absorbed by the phase change material, a quantity of heat that is equal to the enthalpy variation associated with this transformation. Thus, the fact that the calories are absorbed by the phase change material causes a local lowering of the temperature of the wax layer, which increases the viscosity of the applied layer and subsequently increases its adhesion to the depilatory hairs. .

On the one hand, therefore, a uniform thin layer application of a depilatory wax composition on the skin is obtained, in particular due to its fluidity due to the heating at a relatively high temperature, and, on the other hand, a local lowering of its temperature and consequently an increase in its viscosity, which allows the wax layer to adhere better to the bristles and to the support of the strip. tear.

Preferably, the transition temperature of said phase change material is between 25 and 35 ° C.

Thus, the use of a phase change material having the aforementioned values of its transition temperature ensures a good lowering of the local temperature of the applied wax layer, given the ratio between the volume of the wax layer and the that of the support containing the phase change material. In addition, because the transition temperature of the phase change material is lower than that of human skin, it has been found in laboratory tests that a decrease in the temperature of the wax layer provides painkiller effect when pulling hair with the band. This contributes to the comfort of hair removal and partially mitigates the vasodilator effect of heat.

Advantageously, said support contains at least two different types of phase change materials.

A phase change material is characterized by its transition temperature, in this case of melting, and by its ability to store heat, expressed in J / g. The use of two or more types of phase change materials with the same tape support can cover a wider range of temperatures, or even vary the transition time interval in larger ranges than with a single one. type of material.

Preferably, said phase change material is a paraffin.

Paraffin means a paraffinic hydrocarbon which has melting temperatures in the aforementioned range and good capacity to store heat. Such paraffins may be, for example, heneicosane, eicosane, nonadecane, octadecane, heptadecane, etc. In addition, paraffin is very well supported by the skin, it can be brought into contact with the skin without causing allergies or adverse skin reactions.

Advantageously, said phase-change material is contained in a plurality of microcapsules spread in said support.

It would have been possible, of course, to apply the phase-change material by spraying on the tear strip support, or by coating one side of the strip with such a material, or by dipping the support of the strip in a bath. of such a material, the support then wrapped in a protective film. However, it is preferred to apply to the tape support a phase change material contained in a plurality of microcapsules enclosed in protective envelopes of a few microns in diameter. The protective casing prevents the liquid phase flow of the phase change material and allows it to return to the initial state within the confines of the casing. The micro capsules also have the advantage of having good resistance to mechanical actions (pressure, traction, shear) and good chemical stability (washing, contact with the components of the wax depilatory), while having constant dimensions which allows their application in a uniform layer on the tape support or allows them to be well mixed with the fibers of the support.

Usefully, said material is applied on the inner face of said strip in a layer with a thickness of less than 3 mm, preferably between 0.01 mm and 0.5 mm.

In order to have a good effect of local temperature reduction, it is preferred to apply the microcapsules in a uniform layer on the internal face of the support of the strip, in particular the face intended to be applied to the zone. wax-coated, the thickness of the layer of micro capsules to be in this case comparable to that of the layer of wax applied to the skin, preferably less than the latter.

Preferably, said microcapsules are suspended in an aqueous solution in a proportion of 30 to 80% by weight of microcapsules.

An aqueous solution of such a concentration makes it possible to easily transport the microcapsules to the support, while obtaining the necessary amount after the evaporation of the water.

Advantageously, a binder in aqueous suspension is added to said micro-capsule solution in a proportion of between 0 and 50% by weight of binder.

This binder may be, for example, an emulsion of acrylic type which has good adhesion properties to the fibers of the strip support and allows better adhesion of the particles to the support, having the effect of a better resistance to the mechanical actions performed on the strip or to successive washes of the band.

Preferably, said phase change material is spray deposited on said support.

This solution has the advantage of being easy to implement because it is possible to quickly deposit the micro capsules on their support, the latter adhering to the fibers of the support after drying.

In a variant of the invention, said wax is a water-soluble depilatory wax comprising at least one sugar.

Said sugar is chosen from the group comprising sucrose, fructose, glucose, honey, maple syrup, invert sugars, alone or as a mixture. Such a wax depilatory is a viscous substance of the non-hardening glue type. She is initially heated to about 50 ° C so that it can be applied as a thin layer to the skin and is then removed with the bristles that it includes by means of a tear strip placed on the skin area covered with wax .

In another variant of the invention, said wax is a rosin-type depilatory wax.

Rosin-type depilatory wax comprises a depilatory composition of the resin type, that is to say based on rosin (comprising resin acids) or modified rosin, beeswax or paraffin and optionally comprising an elastomer or other thermoplastics. Such wax is in the solid state at room temperature and should be heated to about 70 ° -80 ° C to make it fluid for application to the skin. Once applied to the skin, the wax strip can be removed by pulling on one of its ends or by affixing a support band and removing it with the latter.

In yet another variant of the invention, the depilatory wax may be a mixture of a rosin-type wax with an aqueous solution, or with a water-soluble type of epilating wax containing sugar or any other hydrodispersible mixture of waxes depilatory, optionally comprising a surfactant or other additives.

Advantageously, the tear strip of the invention comprises micro capsules containing cosmetic active ingredients.

These cosmetic active agents are chosen from the group comprising perfumes, essential oils, opacifiers, antiseptics, analgesics, cooling agents, such as for example menthol, dyes, plasticizers, salts, alone or as a mixture. These products can also be micro-encapsulated and are applied to the tape support in the same way, or even at the same time by being mixed in the same aqueous solution before application, their use being intended to make the epilation operation more pleasant .

According to a preferred embodiment of the invention, said support is spray-treated with an aqueous solution comprising a proportion of 95% to 40% by weight of a first solution, comprising 38.6% by weight of microparticles. a paraffin having a melting temperature of 25 ° C in aqueous suspension, mixed with 5% to 60% of a second solution, comprising 50% by weight of an acrylic binder in aqueous suspension.

The invention also relates to a depilatory process using a depilatory wax composition comprising a step of applying a layer of softened wax to a skin area, and a step of removing the bristles embedded in the layer. applied wax, characterized in that it comprises an additional step of applying a phase change material to the layer of wax deposited on the skin, said material having a transition temperature lower than that of application of the depilatory wax on the skin, wherein said material is charged in calories by contact with the wax layer.

The invention will be better understood on reading the description below, as well as on reading the examples taken in a non-limiting manner.

A tear strip according to the invention comprises a support consisting of a piece of fabric, for example raw or bleached cotton, or a nonwoven material, for example polyester, or knitted, or cellophane, of paper, plastic film or any other material in sheet or thin plate, being relatively flexible to easily adapt to the shape and relief of the area of skin to be treated. This support must have good resistance properties to mechanical stress made by the user on one end of the band, including tearing, shearing and traction.

The dimensions of such a band are chosen according to the dimensions of the area to be depilated. For example, a tear strip holder for the depilation of the legs is of rectangular shape of length between 10cm and 30cm and a width of between 4cm and 8cm.

The phase change material is selected from the group of paraffinic hydrocarbons having a melting point below 45 ° C. Such paraffinic hydrocarbons may be, for example, heneicosane having a melting point of 40.5 ° C. and having a heat storage capacity of 213 J / g, or eicosane having a melting point of 36.1 ° C and has a heat storage capacity of 247J / g, the nonadecane whose melting temperature is 32.1 ° C and has a heat storage capacity of 222J / g, octadecane having a melting point of 28.2 ° C and having a heat storage capacity of 244J / g, heptadecane having a melting point of 22.5 ° C and having a heat storage capacity 214J / g.

The phase change material is contained in gelatin protective casings of the microcapsules having dimensions of, for example, between 1 and 40 μm. These micro capsules can be integrated in the fibers of the support, in foams then adhered to the support, or in coating layers.

According to a preferred embodiment of the invention said support is spray-treated with an aqueous solution comprising a proportion of 95% to 40% by weight of a first solution, comprising 38.6% by weight of micro-capsules of a paraffin having a melting temperature of 25 ° C in aqueous suspension, mixed with 5% to 60% of a second solution, comprising 50% by weight of an acrylic binder in aqueous suspension. Additives or cosmetic actives in the form of micro capsules in a proportion of 0 to 15% can also be incorporated into the solution.

In the context of this embodiment, a non-woven polyester strip is used as support, several possible mixtures have been tested to obtain, in the dry state, a predetermined weight of micro capsules and binder with respect to the weight of the support band which is, for example, 1g.

In a first embodiment of the invention, to obtain 80% by weight of microcapsules and 5% of binder with respect to the weight of said support strip, 2.14 g of a 95% solution mixture containing 38.6% of microcapsules in aqueous suspension and 5% of solution comprising 50% of acrylic binder in aqueous suspension.

In a second embodiment of the invention, to obtain 50% by weight of microcapsules and 5% of binder with respect to the weight of said support strip, 1.4 g of a mixture containing 93% of solution containing 38.6% of microcapsules in aqueous suspension and 7% of solution comprising 50% of acrylic binder in aqueous suspension.

In a third embodiment of the invention, to obtain 50% by weight of microcapsules and 20% of binder with respect to the weight of said support strip, 1.7 g of a 75% mixture of solution containing 38.6% of microcapsules in aqueous suspension and 25% of solution comprising 50% of acrylic binder in aqueous suspension.

In a fourth embodiment of the invention, to obtain 10% by weight of microcapsules and 5% of binder with respect to the weight of said support strip, 0.36 g of a mixture containing 72% of solution containing 38.6% of microcapsules in aqueous suspension and 28% of solution comprising 50% of acrylic binder in aqueous suspension.

In a fifth embodiment of the invention, to obtain 10% by weight of microcapsules and 20% of binder with respect to the weight of said support strip, 0.66 g of a 40% solution mixture containing 38.6% of microcapsules in aqueous suspension and 60% of solution comprising 50% of acrylic binder in aqueous suspension.

According to this embodiment, the tape carrier is coated on one of its faces, in particular that which will be applied to the zone of skin to be depilated, with the previously described solution which is sprayed on said support. The band is then dried in a ventilated oven at 60 ° C to remove water. The band thus obtained is ready to be used, several uses and successive washes being possible with such a band.

During the epilation operation, a thin layer, for example a thickness of between 0.5 mm to 1 mm, of depilatory composition heated to a temperature of between 50 ° C. and 70 ° C. is applied to the skin, depending on the type of depilatory composition used. The application temperature of the wax layer on the skin may be equal to or lower than 45 ° C. A tear strip treated as previously described is then applied to the skin area coated with depilatory wax. The micro-capsules of the tape support absorb the calories stored by the wax, which results in a decrease in the local temperature of the wax layer and, at the same time, an increase in the viscosity of the wax resulting in a better efficiency at the wax. the pulling of the hairs. At the same time the comfort of the depilation is improved and it is partly compensated for the vasodilator effect due to the application temperature of the wax on the skin.

The effect obtained with such a band is reversible, the phase change material returning to its solid state as soon as the temperature has dropped below its crystallization temperature.

Other variants and embodiments of the invention may be envisaged without departing from the scope of its claims.

Thus, it is possible to envisage the application of the phase-change material, contained or not in microcapsules, directly onto the layer of wax applied to the skin. Thus, if the applied wax is of the rosin and self-supporting type, the phase-change material is taken in the wax strip and can be removed with it when it is pulled up. In the case where the wax can be removed with a tear strip, it is also conceivable to apply, for example by spraying, the phase-change material on the wax layer already deposited on the skin, and then affix the tear strip on the area of skin coated with wax and said material and finally tear with the hair depilatory.

In another variant, it is possible to further coat the outer face of said support with a thermochromic material and follow, by the color change, the drop in temperature that has occurred following the application of the phase-change material to the skin.

Claims (14)

1. A peel strip for application to a zone of skin that is covered in a layer of epilation wax, the strip comprising a medium of flexible material, and being characterized in that said medium contains a phase-change material having a transition temperature lower than the temperature at which the epilation wax is applied to the skin, where said phase-change material takes up heat on contact with the layer of wax.
2. A peel strip according to claim 1, characterized in that the transition temperature of said phase-change material lies in the range 25°C to 35°C.
3. A peel strip according to claim 1, characterized in that said medium contains at least two different types of phase-change material.
4. A peel strip according to any preceding claim, characterized in that said phase-change material is a paraffin.
5. A peel strip according to any preceding claim, characterized in that said phase-change material is contained in a plurality of microcapsules distributed through said medium.
6. A peel strip according to any preceding claim, characterized in that said material is applied onto the inside face of said strip in a layer having a thickness less than 3 mm, preferably lying in the range 0.01 mm to 0.5 mm.
7. A peel strip according to claim 5, characterized in that said microcapsules are in suspension in an aqueous solution at a concentration representing 30% to 80% by weight of microcapsules.
8. A peel strip according to claim 7, characterized in that a binder is added to said solution of microcapsules, the binder being in aqueous suspension at a concentration lying in the range 0 to 50% by weight of binder.
9. A peel strip according to any preceding claim, characterized in that said phase-change material is deposited on said medium by spraying.
10. A peel strip according to any preceding claim, characterized in that said wax is a hydrosoluble epilation wax including at least one sugar.
11. A peel strip according to any preceding claim, characterized in that said wax is a rosin type epilation wax.
12. A peel strip according to any preceding claim, characterized in that it includes microcapsules containing cosmetic active agents.
13. A peel strip according to any preceding claim, characterized in that said medium is treated by being sprayed with an aqueous solution comprising 95% to 40% by weight of a first solution having 38.6% by weight microcapsules of a paraffin with a melting temperature of 25°C in aqueous suspension, mixed with 5% to 60% of a second solution comprising 50% of weight of an acrylic binder in aqueous suspension.
14. A method of epilation using an epilation wax composition, the method comprising a step of applying a layer of softened wax on a zone of skin, and a step of peeling off the hairs caught in the applied layer of wax, the method being characterized in that it includes an additional step of applying a phase-change material on the layer of wax deposited on the skin, said material having a transition temperature lower than the temperature at which the epilation wax is applied to the skin, where said material takes up heat on contact with the layer of wax.