Patent Description:
The use of biodegradable materials is one of the most effective approaches to contribute to the resolution of environmental pollution problems that arise, among other things, from the huge use of petrochemical plastic materials.

The raw materials used in cosmetics can have a petrochemical, synthetic, animal or vegetable origin. Some petrochemical raw materials will even be banned in some States by <NUM> (e.g. in California, a State in the vanguard as regards legislation in the U. ) due to the pollution caused to the aquifers. These non-biodegradable materials escape from sewage treatment plants and are released into the environment with threats to aquatic species.

The most obvious green alternative to these types of cosmetic raw materials undoubtedly are biopolymers, which combine the plant origin of the starting raw materials (biomass fermentation) with the versatility of synthesis chemistry. For this reason, it is strategic to address the innovation effort towards raw materials of plant origin, which are varied through chemical synthesis, possibly applying the principles of "Green Chemistry".

In this regard, more and more attention is being paid to the study and modification of polylactic acid (hereinafter "PLA") which is the most promising biopolymer to date due to its complete biodegradability, good thermal processability, renewability, good mechanical performance, etc..

This polymer has been extensively studied over the last <NUM> years and scientific and technical knowledge has enabled the emergence of the first industrial applications to date. In fact, PLA has already found extensive use in a variety of fields, and in particular in the biomedical sector: due to its biocompatibility and biodegradability, it has been found to be effective in the manufacture of medical devices for the controlled release of drugs, plaques and nails for bone fixation, surgical sutures which, in contact with the body, have shown a decrease in inflammatory reactions and infections. Another great search front is packaging: packaging in fact has a considerable environmental impact and therefore it is natural to use compostable and biodegradable materials to reduce the impact thereof.

PLA has so far found cosmetic use only in the form of powder with texturizing purpose in decorative cosmetics and as a scrub in rinsing products. PLA cosmetic powders were marketed by Honeywell International, Inc. under the trade name of Asensa and by Daito Kasei Kogyo Co. under the trade name of Ecobeads.

To date, the most effective polymerization method at industrial level for the synthesis of PLAs with high molecular weight envisages a ring opening polymerization (hereafter "ROP") starting from the cyclic dimer of lactic acid (lactide).

The synthesis of biopolymers containing PLA through ROP is well known in the literature and a lot of scientific evidence has described and analyzed various processes for obtaining said biopolymers or co-polymers containing PLA. It is also known in the art that polymerization of lactate by ROP occurs efficiently in the presence of organometallic catalysts (e.g. tin(II) ethylhexanoate) at high temperature and with the aid of alcoholic co-initiators.

For example, <NPL>) describes the synthesis of PLA and polydimethylsiloxane copolymers (hereafter "PDMS"). Said copolymers are obtained by trans-esterification reaction between poly(dimethyl siloxane) bis (<NUM>-aminopropyl ether) with PLA, in a chloroform solution and in the presence of stannous octoate.

<NPL>) describes the synthesis of polyester and polydimethylsiloxane copolymers by ROP initiated by alcoholic co-initiators.

<NPL>) describes cold crystallization of copolymers of poly(L-lactide-b-dimethylsiloxane-b-L-Lactide) by ROP of L-lactide using bis(hydroxyalkyl)-terminated PDMS as macroinitiator.

<NPL>) describes the synthesis of copolymers of poly-lactide and PDMS. The copolymers are produced by the reaction of lactide and α,ω-bis(<NUM>-hydroxypropyl) PDMS.

<NPL>) describes a method of ROP of lactide in the presence of PDMS as macroinitiator and a catalyst.

<CIT> describes a polyester compound suitable for cosmetic uses obtained by ROP of lactide in the presence of a silicone.

<CIT> describes the use of PLA as a primary component of cosmetic products.

<CIT> describes an amorphous biodegradable PLA extracted from plants.

<NPL>, concerns polylactide-poly(dimethylsiloxane)-polylactide triblock copolymers obtained by the reaction of D,L-lactide and a commercially available α,ω-<NUM>-(<NUM>-hydroxyethoxy)propyl-terminated PDMS microinitiator in the presence of tin octoate. This plymer is suitable to be used as a cosmetic product.

The above reactions take place at high temperatures even in the presence of alcoholic initiators or co-initiators, said reactions allow to obtain high molecular weight copolymers with chemical and physical properties that do not allow a wide use thereof in cosmetics.

The object of the present invention is to obtain biodegradable copolymers for cosmetic use with a wide possibility of use in the cosmetic field.

Another object is to obtain biodegradable copolymers whose fluidity can be changed only by varying the proportion of the moles of the starting reagents.

A further object is to obtain biodegradable copolymers for cosmetic use with a low environmental impact and unprecedented textures.

According to the invention, such objects are achieved with biodegradable copolymers for cosmetic use as described in claim <NUM>.

The object of the present invention is a method for the preparation of biodegradable block copolymers "A-B-A", consisting of a central polysiloxane block (PDMS) called "B", and two symmetrical PLA blocks, called "A", PLA-PDMS-PLA and their use in cosmetic products. The applicant's research has in fact shown that the properties of these materials vary continuously and predictably with the variation of the PLA/PDMS ratio and the molecular weights of the two constituent blocks A and B.

Via chemical synthesis it is therefore possible to access a series of compatible chemical compounds with different consistencies, from fluid materials to pastes, to plastic materials, up to hard solid materials. Such a wealth of behaviors can be suitably used in the formulation of new cosmetic products which have a reduced environmental impact and unprecedented textures.

It is known in the art that polymerization of lactate by ROP occurs efficiently in the presence of organometallic catalysts (e.g. tin(II) ethylhexanoate) at high temperature and with the aid of alcoholic co-initiators.

In the present invention, in lieu of low molecular weight alcohols, a linear or branched silicone macroinitiator with alcoholic functionality in α and ω terminal position is used to start the chain reaction and symmetrically add the PLA terminal blocks to the central polysiloxane one.

Depending on the amount of polymerized lactide, final molecular weights may be reached ranging from <NUM> Da to more than <NUM> kDa and therefore materials with markedly different features.

These and other features of the present invention will be apparent from the following detailed description and embodiment examples thereof.

Hereinafter, the PLA-PDMS copolymers obtained will be named with the fantasy name "Diplathicone".

The following Table <NUM> gives an indication of the features that can be obtained by varying the proportions between silicone segment and PLA segment.

Diplathicone LV, V-HV and powder are not according to the invention.

The opportunity is even more interesting in view of the fact that, although such materials are described in scientific and patent literature, their use is not described or protected in cosmetics.

In this regard, it is noted that the CTFA dictionary only reports the following materials based on building blocks of lactic acid.

PDMS has high oxygen and water vapor permeability and is biocompatible, making the block copolymer, which is formed by the reaction with lactide, highly biocompatible and therefore of great importance to many fields, including cosmetics.

The possibility to modulate the fluidity of a cosmetic raw material obtained as described above, without changing the chemical composition but only the ratio in moles between the silicone component and the starting lactide, allows to obtain a wide family of cosmetic raw materials that can then be used in all types of cosmetics: face products (concealer, foundation, tinted creams,. ), lip products (lipsticks, lip balms,. ), eye decoration products (compact powders, fluids,. ), hair products, nail care and decoration products in all their physical forms (solid, liquid, gels or pastes).

More specifically, the reaction is conducted by reacting at least one linear and branched silicone initiator with at least one alcoholic functionality in α and ω terminal position, for example a cosmetic bis-hydroxyterminated dimethicone that is selected from the group comprising Carbinol bis-hydroxyterminated Polydimethylsiloxanes Baysilone OF OH <NUM> E (Momentive Performance Materials), Dow Corning <NUM> Carbinol Fluid (Dow Corning Corporation), Emulsil S-<NUM> (Innospec Performance Chemicals), Carbinol bis-hydroxyterminated Polydimethylsiloxanes : DMS-C15, DMS-C16, DMS-C21, DMS-C23, DBE-C25, DBL-C31, DBP-C22 (Gelest), MonoCarbinol terminated Polydimethylsiloxanes: MCR-C12, MCR-C13, MCR-C18, MCR-C22 (Gelest), MonoDiCarbinol terminated Polydimethylsiloxanes: MCR-C61, MCR-C62 (Gelest), Linear and branched Hydroxy Functional Pre-Polymers: Silmer OH A0, Silmer OH C50, Silmer OH J10, Silmer OH Di-<NUM>, Silmer OH Di-<NUM>, Fluorosil OH C7-F (Siltech) with the lactide, L-lactide, D-lactide or LD-lactide, for example L-lactide (e.g. Puralact (Corbion)).

Preferably, said silicone initiator is Carbinol bis-hydroxyterminated Polydimethylsiloxanes Baysilone OF OH <NUM> E (Momentive Performance Materials) or Dow Corning <NUM> Carbinol Fluid (Dow Corning Corporation).

The silicone initiator according to claim <NUM> is hydroxyethoxypropyl dimethicone.

Said silicone initiator has a molecular weight greater than <NUM> Da, preferably greater than <NUM> Da, even more preferably between <NUM> Da and <NUM> Da.

Ring opening polymerization requires a catalyst that can be selected from zinc compounds such as zinc lactate, zinc(II) <NUM>-ethylhexanoate, zinc stearate and tin compounds, such as tin octoate (tin (II)-<NUM>-ethylhexanoate) or tin alkoxides, or <NUM>-(Dimethylamino)pyridine N-heterocyclic carbenes, <NUM>,<NUM>-bis-(<NUM>,<NUM>,<NUM>-trimethylphenyl)imidazol-<NUM>-ylideneN-heterocyclic carbenes, <NUM>,<NUM>-bis-(<NUM>,<NUM>,<NUM>-trimethylphenyl)imidazolinium chloride Na salt of <NUM>,<NUM>-di-tert-butyl-<NUM>-methylphenol, Tin(II) <NUM>-ethylhexanoate.

The lactide, preferably L-lactide and the silicone initiator are added with different percentages by weight. The lactide will have a concentration by weight of between <NUM>% and <NUM>%.

The silicone initiator will have a concentration by weight of between <NUM>% and <NUM>%. The catalyst will have a concentration by weight of between <NUM>% and <NUM>%.

At the end of the reaction between the lactide and the silicone initiator, biodegradable copolymers can be obtained having different chemical and physical properties, such as molecular weight, viscosity and density. These copolymers can take a clear fluid consistency at room temperature, or a milky fluid, or a paste, or even a solid.

Biodegradable copolymers have a molecular weight of between <NUM> Da and <NUM> kDa, preferably between <NUM> Da and <NUM> kDa, even more preferably between <NUM> Da and <NUM> kDa.

Moreover, said copolymers have a Brookfield viscosity v of between <NUM> mPa-s (<NUM> cP) and <NUM> mPa-s (<NUM> cP) and a density of between <NUM>/cm<NUM> and <NUM>/cm<NUM> at <NUM>, preferably between <NUM>/cm<NUM> and <NUM>/cm<NUM>, even more preferably between <NUM>/cm<NUM> and <NUM>/cm<NUM> at <NUM>.

In the presence of a catalyst, the lactide and the silicone initiator are made to react with a lactide concentration of between <NUM>% and <NUM>% by weight and a silicone initiator concentration of between <NUM>% and <NUM>% by weight. The copolymers obtained from said reaction will have the consistency of a paste at room temperature, with a molecular weight GPC Mw of between <NUM> Da and <NUM> Da, preferably between <NUM> Da and <NUM> Da, even more preferably between <NUM> Da and <NUM> Da, a Brookfield viscosity v of between <NUM> mPa-s (<NUM> Cp) and <NUM> mPa- s (<NUM> Cp), preferably between <NUM> mPa-s (<NUM> Cp) and <NUM> mPa-s (<NUM> Cp), even more preferably between <NUM> mPa-s (<NUM> Cp) and <NUM> mPa-s (<NUM> Cp). The resulting products do not have a melting/crystallization point detectable with standard techniques, such as differential scanning calorimetry, in the range in which the PLA has a melting/crystallization point of between <NUM> and <NUM>.

The following examples are intended to clarify the present invention without limiting it in any way.

To a <NUM> five-neck glass jacketed reactor (mechanical stirring, downpipe, thermometer, nitrogen inlet and neck for adding reagents) are added <NUM> L-lactide, <NUM> Dimethicone bis-hydroxyterminated (Bis-hydroxyethoxypropyl Dimethicone, DC <NUM> Carbinol Fluid) and <NUM> tin(II) <NUM>-ethylhexanoate. After flushing dry nitrogen for one hour, the internal temperature is brought to <NUM> and allowed to react to complete depletion of lactide, controlled by infrared spectroscopy. At the end of the reaction, the internal temperature is brought to <NUM> and a clear fluid is discharged, having a molecular weight GPC Mw = <NUM> Da, Brookfield viscosity v= <NUM> mPa-s (<NUM> cP) and density d = <NUM>/cm3 at <NUM>.

To a <NUM> five-neck glass jacketed reactor (mechanical stirring, downpipe, thermometer, nitrogen inlet and neck for adding reagents) are added <NUM> L-lactide, <NUM> Dimethicone bis-hydroxyterminated (Bis-hydroxyethoxypropyl Dimethicone, DC <NUM> Carbinol Fluid) and <NUM> tin(II) <NUM>-ethylhexanoate. After flushing dry nitrogen for one hour, the internal temperature is brought to <NUM> and allowed to react to complete depletion of lactide, controlled by infrared spectroscopy. At the end of the reaction, the internal temperature is brought to <NUM> and a milky fluid is discharged, having a molecular weight GPC Mw = <NUM> Da, Brookfield viscosity v= <NUM> mPa-s (<NUM> cP) and density d = <NUM>/cm3 at <NUM>.

To a <NUM> five-neck glass jacketed reactor (mechanical stirring, downpipe, thermometer, nitrogen inlet and neck for adding reagents) are added <NUM> L-lactide, <NUM> Dimethicone bis-hydroxyterminated (Bis-hydroxyethoxypropyl Dimethicone, DC <NUM> Carbinol Fluid) and <NUM> tin(II) <NUM>-ethylhexanoate. After flushing dry nitrogen for one hour, the internal temperature is brought to <NUM> and allowed to react to complete depletion of lactide, controlled by infrared spectroscopy. At the end of the reaction, the temperature is lowered to <NUM> and a milky fluid is discharged that at room temperature takes the consistency of a translucent viscous paste. The material has a molecular weight GPC Mw = <NUM> Da, Brookfield viscosity v= <NUM> mPa-s (<NUM> cP) at <NUM>.

To a <NUM> five-neck glass jacketed reactor (mechanical stirring, downpipe, thermometer, nitrogen inlet and neck for adding reagents) are added <NUM> L-lactide, <NUM> of monofunctional silicone carbinol (MCR-C18, Gelest, Inc. ) and <NUM> zinc(II)stearate. After flushing dry nitrogen for one hour, the internal temperature is brought to <NUM> and allowed to react to complete depletion of lactide, controlled by infrared spectroscopy. At the end of the reaction, the temperature is lowered to <NUM> and a translucent fluid is discharged that at room temperature takes the consistency of a white viscous paste. The material has a molecular weight GPC Mw = <NUM> Da, Brookfield viscosity v= <NUM> mPa-s (<NUM> cP) at <NUM>.

The diplathicones prepared as described above, are characterized by the unique combination of two typical properties of their constituents: like dimethicones, the reduced surface tension (see Table <NUM>) facilitates the spreading thereof while they show a typical adhesion in more polar systems, such as polyesters.

A first application of diplathicones is that of single binding phase in powdered cosmetic products. Compact powders in which diplathicone LV (not according to the invention) is present have a good flowability and a silky texture (Examples <NUM> and <NUM>). In the specific case of compact powder eye shadows (Example <NUM>), a texture is obtained that is just as interesting and creamy, combined with long hold, tested by a panel of <NUM> volunteers. Moreover in the drop test, which is carried out to evaluate the cohesive properties of a binder, the pieces show high values, well above the limit of acceptability.

In a second application, mixtures of diplathicones with different molecular weights and viscosities allow to formulate a lip balm (Example <NUM>) with excellent spreadability, whereby a uniform film with high gloss and good coverage can be applied to the lips.

The diplathicones can be used not only as oils but also as functional ingredients in cosmetic formulations. Due to their block structure, they can act as compatibilizing agent between esters and silicones in anhydrous products. In fact, in a third application (Example <NUM>), the diplathiconediplathicones can be added to cosmetic formulations of lipstick with a high content of silicone and esters.

The resulting cosmetic products have no incompatibility phenomena, such as unmixing or seeping, phenomena that usually occur when there is an incompatibility between wax and oil or between different oils. Moreover, the stick lip product (Example <NUM>), where diplathicone MV is present, shows greater brilliancy than the product in which the diplathicone is absent. Finally, an increase in the concentration of diplathicone MV (Example <NUM>) within the formulation of the lipstick greatly improves the cosmetic performances of hold and adherence thereof; maintaining a high ease of application.

Likewise, diplathicones are able to effectively disperse a waxy phase as in the following fourth application (Examples <NUM>, <NUM> and <NUM>). In the examples, the diplathiconediplathicones used stabilize and complex the melted wax. In Example <NUM>, the combination of diplathicone and solidified wax generates a semisolid compound that can be taken with a brush and easy to apply. Properly pigmented, such a material can be used as an anhydrous eyeliner for eye decoration.

A fifth application is the use of diplathicones as functional ingredients to impart silicone character to formulations in which it is currently impossible to introduce silicones in high percentage. A salient example are nail polishes (Example <NUM>) where silicones are added in quantities of less than <NUM>% as anti-foaming agents due to the known incompatibility with nitrocellulose and other ingredients known in art and used in such products. The presence of polyester blocks at the ends of the silicone block gives the diplathiconediplathicones compatibility with nitrocellulose, with which it forms hard films having high optical quality (bright and clear).

Diplathicone HV in this application can completely replace traditional resins used in the formulation of polishes. The segregation of silicone blocks to the surface of the film gives the polish a slippery and lubricated surface touch, allowing the creation of innovative textures and improving shine and hold.

The following product was obtained by a process of dispersion of powder in a solvent, isododecane. Phase C was dissolved at <NUM> in isododecane, then phase B was added until completely dissolved and finally phase A was added. The mixture thus obtained was homogenized by treatment with a turbine. The resulting dispersion was placed in an oven at <NUM> for <NUM> to allow the evaporation of the solvent. The powder obtained after evaporation of the solvent was then sieved and compacted.

The eye shadow was prepared by dissolving phase A at <NUM>, after complete dissolution was added phase B under mechanical stirring and cast into jars.

The cast eye shadow was obtained by dissolving phase A at <NUM>, then the powder phase was added under mechanical stirring; the product thus obtained was cast directly into a jar.

The eyeliner was prepared as in example <NUM>.

The fluid lip balm was obtained by mixing phase A at <NUM> for <NUM> minutes. Phase B was laminated at room temperature for about <NUM> minutes and was added to phase A under mechanical agitation until complete dispersion for additional <NUM> minutes. The product was then packaged in a bottle with sponge applicator.

The lipstick was obtained by melting phase A at <NUM> and laminating the pigment with the oil phase. Thereafter, phase B was combined with phase A and the two phases were mixed by mechanical stirring. When the mixture became homogeneous, it was cast into special silicone nose-cones, previously heated. The samples were placed on a cooling plate for later extraction of the lipsticks.

The lipstick was prepared as in Example <NUM>.

The transparent polish base for nails was prepared by mixing the three phases at room temperature; this base can be easily colored by adding a pigment (e.g. Red7 lacquer).

Advantageously, the biodegradable copolymers described have a very low environmental impact and a wide versatility in cosmetics.

Claim 1:
Cosmetic product comprising a biodegradable copolymer of PLA-PDMS-PLA blocks, wherein PLA indicates a polylactic acid block and PDMS indicates a polydimethylsiloxane silicone initiator block, the copolymer being obtained by reaction between L or D lactides, a linear or branched silicone initiator with at least one alcoholic functionality in α and ω terminal position and a catalyst, wherein the silicone initiator is bis-hydroxyethoxypropyl dimethicone and has a molecular weight greater than <NUM> Da, the reaction being conducted with a weight concentration of lactide comprised between <NUM>% and <NUM>%, a weight concentration of silicone initiator comprised between <NUM>% and <NUM>% and a weight concentration of catalyst comprised between <NUM>,<NUM>% and <NUM>%, and the biodegradable copolymer has a viscous paste consistency at room temperature with a molecular weight GPC Mw comprised between <NUM> Da and <NUM> Da, and a Brookfield viscosity v comprised between <NUM> mPa-s (<NUM> Cp) and <NUM> mPa-s (<NUM> Cp) at <NUM>.