COMPOSITION FOR STRIP-FREE HAIR REMOVAL

Description

Technical background

[0001] The invention falls within the field of hair removal compositions for removing hair, particularly for human use and in particular, but without this being limiting, for professional use.

[0002] We know of compositions based essentially on rosin, which is a solid residue from the distillation of products from resinous trees, notably pine. Rosin is a resin with tackifying properties (i.e., having adhesion properties). Rosin is the largest fraction of these compositions and is mixed only with small fractions of fatty products such as oils or lanolin and waxes. These compositions require, before their application, to be heated for a long time before being soft enough to be applied to the skin. In certain situations, the temperature obtained is too high, which is dangerous or unpleasant for the person to be depilated. Furthermore, the thickness of the composition to be applied is necessarily significant (5 mm for example), due to the poor mechanical strength of the composition once spread. These compositions are, however, reusable after filtration.

[0003] Compositions are also known, still containing rosin, but also comprising oils in higher proportions than in the previous example, and possibly comprising sugars or waxes, with a suitable softening point (softening at a lower temperature than the previous compositions), and which require less heating. However, these compositions require the use of a support film (paper or cotton strip / cellulose or plastic strip, such as cellophane film) to remove them once they are applied to the skin, again due to the poor mechanical strength of the composition. These compositions are not reusable, and are discarded after use. Compositions of this type are known, for example, through document FR2577134. Other compositions of this type using a synthetic resin instead of rosin are also known from document WO2008 / 103817.Synthetic resins are described later in this text.

[0004] In this context, the invention relates more specifically to a composition for hair removal by pulling out hairs that does not require a paper or plastic strip to be applied. The composition has mechanical properties that are such that the use of such a strip is in fact unnecessary. However, it can be applied in a thin layer.

[0005] We know of compositions of this type, for example, through documents FR2617708, FR2637498, FR2751872 and FR2751873.

[0006] Generally speaking, such compositions primarily contain a resin with tackifying properties and a macromolecular compound providing mechanical properties. Other constituents are present in the composition, such as softeners or softeners, such as waxes or oils.

[0007] Tackifying resin is often a rosin, that is, as mentioned above, a resin of natural origin. Rosin molecules contain oxygen atoms and have a certain polarity. It can be unmodified (acidic) rosin or modified by hydrogenation, esterification, or dimerization. Alternatively, a synthetic resin, derived from petroleum product fractions, can be used. This is a set of carbon molecules that are generally less polar than rosin.We know synthetic resins called C5 (copolymers based on diene monomers - aliphatic - such as pentadiene, methylbutene, dicyclopentadiene, cyclopentadiene and cyclopentene), mostly cyclopentadiene, and synthetic resins called C9 (copolymers based on aromatic monomers such as vinyltoluene, dicyclopentadiene, indene, methylstyrene, styrene and methylindene), mostly a styrene / methylstyrene / indene copolymer. These resins exist in different grades and can also be modified, notably by hydrogenation.

[0008] The resin, whether natural or synthetic, is generally the compound present in the greatest proportions, by weight, in the composition.

[0009] The macromolecular component providing mechanical properties can be a wax, i.e. a fatty acid ester. It is generally present in proportions, by weight, which are lower than those of the resin. There are animal, vegetable or mineral waxes which can be used, an example being beeswax. They have a certain plastic behavior. The macromolecular component can also be an elastomer, often cheaper, and which can have better mechanical properties, particularly in terms of tensile strength and flexibility or suppleness, due to the absence of glassy behavior in the temperature range used. The introduction of these elastomers by mixing, into the resin which has an initially glassy behavior, makes it possible to provide an amorphous tendency. It can notably be a natural rubber or a synthetic polymer or copolymer such as an ethylene / vinyl acetate (EVA) copolymer.

[0010] Compositions in this category also include softeners and softeners, such as fats, oils or waxes, which also participate in rheological regulation and modulation of setting time.

[0011] These compositions are used by heating leading to its softening, for example around 55°C, then by applying the composition to the parts of the body to be waxed, at a temperature adapted to the comfort of the person to be waxed, who must obviously not feel the temperature too high.

[0012] The compositions mentioned above can be applied in the form of fairly thin layers, and then removed by peeling, after a short solidification and cooling time allowing the hairs to set.

[0013] Compositions are valued by both those undergoing hair removal (e.g., beauty salon clients) and those performing hair removal (e.g., beauticians in beauty salons). Criteria that determine a composition's value include its ability to remove hair (also called "pull-out ability"), its lack of breakage (also called "mechanical properties") when handled as a layer, or the temperature felt on the skin. Some users may place greater value on certain criteria, and it is therefore useful to have a variety of different compositions.

[0014] Despite the presence of various products on the market, there is still room for improvement in offering users solutions that satisfy them all, depending on their preferences, or that simply allow them to change products while maintaining satisfactory properties.

[0015] Moreover, until now, elastomers were compounds used only for their mechanical properties (flexibility and tensile strength) but very little for their adhesion potential. This resulted in an opportunity to seek an increase in adhesion capacities by evolving the compositions.

[0016] It was therefore decided to launch new research in this area. Definition of invention

[0017] To address this problem, an adhesive composition is proposed comprising a main fraction of synthetic tackifying resin and a fraction of at least one macromolecular component. The compositions according to the invention are defined in the set of claims.

[0018] The macromolecular component is an ethylene / octene copolymer, with octene being an alpha-olefin.

[0019] According to various advantageous but optional characteristics: the copolymer is a copolymer produced by catalysis with a metallocene; the copolymer is a copolymer obtained by coordination copolymerization; the copolymer is characterized by a melt flow index of more than 100 g / 10 min (2.16 kg@190°C), or more than 250 g / 10 min (2.16 kg@190°C); the copolymer is characterized by a melt flow index of less than 800 g / 10 min (2.16 kg@190°C), or less than 580 g / 10 min (2.16 kg@190°C); the copolymer is characterized by a density of between 0.86 and 0.91 g / cm3, or between 0.868 and 0.897 g / cm3 or between 0.870 and 0.880 g / cm3; the composition does not contain an ethylene / vinyl acetate copolymer, the ethylene / octene copolymer being present in the composition in a weight fraction of between 5 and 15%; or on the contrary the composition comprises, in addition to the ethylene / octene copolymers, a fraction of an ethylene / vinyl acetate copolymer, the ethylene / octene copolymer and the ethylene / vinyl acetate copolymer being present together in the composition in a weight fraction of between 5 and 15%; the synthetic tackifying resin is, for example, of the cyclopentadiene (C5) type, for example hydrogenated; the synthetic tackifying resin is present in a weight fraction of at least 50%, or even more than 60%, or more than 70%.

[0020] The invention also relates to a hair removal method comprising the application of a layer of an adhesive composition according to the claims comprising a main fraction of synthetic tackifying resin and a fraction of at least one macromolecular component, the application being carried out while the composition has been heated, then the peeling of the layer without the use of a strip, once the composition has cooled. Detailed description

[0021] A reference formula 1 is compared to a formula 2 in which the elastomer components (28% vinyl acetate EVA copolymers) present in formula 1 are replaced by an ethylene octene copolymer, octene being an alpha-olefin. A hydrogenated polycyclopentadiene synthetic tackifying resin is used.

[0022] Formula 1 is shown in the table below: Hydrogenated C5 resin Majority component (>50%) Synthetic waxes Around 10 to 20% EVA (28% VA) (two different compounds) Total EVA: around 10%, between 5 and 15% total 100%

[0023] Fractions are given as the weight of the components relative to the weight of the entire composition. This is also the case in the other formulas in this document.

[0024] Formula 2 is shown in the table below: Hydrogenated C5 resin Like in Formula 1 Synthetic waxes Like in Formula 1 Ethylene / octene copolymer (Affinity GA 1950) As much as EVA in Formula 1 Around 10%, between 5 and 15% total 100%

[0025] Affinity GA 1950 ethylene / octene copolymer component is available from Dow Chemical. It has a melt flow rate of 500 g / 10 min (2.16 kg@190°C) and a density of 0.874. It has a tensile strength of 1.76 MPa.

[0026] Other grades of ethylene / octene copolymers can be used, for example with melt flow indices of more than 100 g / 10 min (2.16 kg@190°C), or more than 250 g / 10 min (2.16 kg@190°C).

[0027] The copolymer may also have a density between 0.86 and 0.91 g / cm3, 0.868 and 0.897 g / cm3, or between 0.870 and 0.880 g / cm3.

[0028] The two waxes used have the following characteristics for illustrative purposes: setting point 58 to 80°C.

[0029] The resin is a hydrogenated C5 resin with a softening point between 85 and 100°C and a molecular weight of 450 to 590 g / mol.

[0030] The EVAs used as reference have melt flow indices of 100 and 500 g / 10 min (2.16 kg@190°C) respectively and densities of both 950 kg / m3. As already mentioned, these are EVAs with 28% vinyl acetate.

[0031] These compositions are applied by hair removal specialists to people undergoing hair removal in blind tests. The composition, initially in granules, is heated in a wax heater until it forms a warm paste. Heating is done between 50°C and 75°C, and preferably 58°C to 68°C. Then the warm paste is applied, for example, with a wooden spatula to form a thin, elongated layer of composition that cools, traps the hairs or sticks them, and hardens.

[0032] This layer, once stiffened by its spontaneous cooling, is grasped at one of its ends and quickly removed in the opposite direction of hair growth, by an operation called peeling. Peeling is thus carried out between 20°C and 38°C, often between 25°C and 35°C.

[0033] Formula 2 has improved tear-off and mechanical properties (no breakage), as well as improved product olfactory properties compared to Formula 1.

[0034] The alpha-olefin used above is an alpha-olefin which is not a propylene.

[0035] It is an octene.

[0036] Of particular interest, without this constituting a limitation of the invention, are plastomer-type copolymers, having more dissipative behavior than the EVAs used up to now.

[0037] The same tests were carried out with compositions based on hydrogenated C9 resin (aromatic tackifying resins).

[0038] The resin used is a hydrogenated C9 resin, with a softening point between 85 and 100°C and a molecular mass of 600 to 800 g / mol.

[0039] Formula 3 is shown in the table below. This is a formula with an ethylene vinyl acetate (EVA) copolymer. Hydrogenated C9 resin Majority component (>50%) Synthetic waxes Around 10 to 20% Beeswax Between 5 and 10% Paraffin oil Between 1 and 3% EVA (28% VA) (two different compounds) Around 10%, between 5 and 15% Scent Low proportion (less than 2%) total 100%

[0040] Formula 4 is shown in the table below. This is a formula with ethylene / octene copolymers Hydrogenated C9 resin Like in Formula 3 Synthetic waxes Like in Formula 3 Beeswax Like in Formula 3 Paraffin oil Like in Formula 3 Ethylene octene copolymer (Affinity GA 1950) Like EVA in Formula 3 Scent Like in Formula 3 total 100%

[0041] Ethylene octene copolymers lead to a composition which has properties at least as good as those of the composition comprising EVA. It is likely that an improvement is possible if the formulas are modified while remaining within the scope of the invention to obtain an optimal result using ethylene octene copolymers.

[0042] Experiments were also conducted with Affinity GA 1950 ethylene / octene copolymers mixed in the same composition with EVA according to the following formulas: Formula 5: Hydrogenated C9 resin Majority component (>50%) Synthetic waxes Around 10 to 20% Beeswax Between 5 and 10% Paraffin oil Between 1 and 3% Ethylene / octene copolymer (Affinity GA 1950) Around 6%, between 2 and 12% EVA (28% VA) Around 4%, between 2 and 10% Pigments Low proportion (less than 2%) Total 100% Formula 6: Hydrogenated C5 resin Majority component (>50%) Synthetic waxes Around 10 to 20% Ethylene / octene copolymer (Affinity GA 1950) Around 5%, between 2 and 12% EVA (28% of VA) Around 5%, between 2 and 12% total 100%

[0043] The results showed an improvement in peeling properties and mechanical properties (absence of breakage), as well as a reduction in residue and odor, compared to the similar composition using only EVA.

[0044] In conclusion, Ethylene / octene copolymers improve the performance of compositions, particularly based on synthetic resins, particularly hydrogenated ones, and offer a new range of products with modified properties. These interesting results are not explained in light of the prior art and were unexpected.

[0045] EVA (28% VA) and ethylene octene copolymers can also act synergistically and provide the product with interesting tear-off and mechanical properties compared to state-of-the-art products.

[0046] The ethylene octene copolymers used above constitute a special case of macromolecular components of the class of copolymers of two or more monomers taken from the group comprising ethylene and alpha olefins.

[0047] For the described application, low crystallinity or even amorphous components are preferred. They are advantageously obtained by coordination polymerization with a Zigler Natta catalyst, for example a metallocene catalyst.

Claims

1. Adhesive composition for strip-free hair removal comprising a main fraction of synthetic tackifying resin and a fraction of at least one macromolecular component, characterised in that the at least one macromolecular component comprises an ethylene and octene copolymer, the octene being an alpha-olefin, the composition not including ethylene-vinyl acetate copolymer, the ethylene / octene copolymer being present in the composition in a fraction of between 5 and 15% by weight, and the synthetic tackifying resin being present in an amount of at least 50% by weight.

2. Adhesive composition for strip-free hair removal comprising a main fraction of synthetic tackifying resin and a fraction of at least one macromolecular component, characterised in that the at least one macromolecular component comprises an ethylene / octene copolymer, the octene being an alpha-olefin, the composition further comprising a fraction of an ethylene-vinyl acetate copolymer, the ethylene / octene copolymer and the ethylene-vinyl acetate copolymer being present together in the composition in a fraction of between 5 and 15% by weight, and the synthetic tackifying resin being present in an amount of at least 50% by weight.

3. Adhesive composition according to claim 1 or claim 2, wherein the synthetic tackifying resin is present in an amount of at least 60% by weight.

4. Adhesive composition according to any one of claims 1 to 3, wherein the copolymer is a copolymer obtained by coordination polymerisation.

5. Adhesive composition according to any one of claims 1 to 4, wherein the polymerisation is catalysed by a metallocene.

6. Adhesive composition according to any one of claims 1 to 12, wherein the synthetic tackifying resin is a cyclopentadiene type resin.

7. Method for hair removal comprising applying a layer of an adhesive composition according to any one of claims 1 to 7, the application being carried out when the composition has been heated, the layer is then peeled off without the use of a strip once the composition has cooled.

8. Method for hair removal method according to claim 7, wherein the synthetic tackifying resin is present in an amount of at least 60% by weight.