Transparent color cosmetic ingredients for cosmetics that may automatically change color when exposed to ultraviolet light

Abstract

The cosmetic ingredient for cosmetics has a polymeric structure including a light-transparent emollient or film-forming cosmetic polymer. Organic chromophore molecules are intercalated and chemically bonded to the polymer, which may be fixed-color molecules or photochromic molecules that can rapidly switch from one color to another. The colored or photochromic molecules are intercalated and chemically bonded to a cosmetic oil by transesterification, which is provided with functional groups suitable for chemically fixing the molecules and chemically bonding them to the oil. The cosmetic oil may be a silicone macrodiol functionalized with a photochromic derivative designed to ensure a transition between a colorless state and a colored state after UV irradiation.

Description

[Technical Field]

[0001] The present invention relates to transparent color cosmetic ingredients for cosmetics that may automatically change color upon exposure to ultraviolet (UV) light.

[0002] Since ancient times, color has been a fundamental element in enhancing beauty, especially female beauty.

[0003] Egyptians used powders and mixtures to decorate their bodies, warriors used them to instill fear in their enemies, and skin coloring was likewise a widespread practice among both indigenous peoples and Native Americans in the Americas.

[0004] First impressions have always been an essential part of everyday life, and a product needs to engage all the senses in order to evoke a range of emotional responses in the consumer.

[0005] Over time, makeup took on more complex and elaborate meanings, becoming a beauty practice aimed at improving the image of the human body.

[0006] Thus, although color psychology has a long history, its evaluation has only recently reached a more scientific approach with the development of models that can predict human emotional responses to colors and their combinations.

[0007] The first theories aimed at explaining the nature of color date back to the 17th century, when it was recognized that color is first and foremost a physical property due to the interaction between light, matter at the electronic level, and the shape of an object.

[0008] A wide variety of dyes are used in cosmetics, and over the years attempts have been made to improve their properties, such as shine, in response to contemporary trends and consumer demands. The continuous development of new trends in the cosmetics market and the specific and diverse demands on cosmetics products means that there is a constant need to develop new, more sophisticated cosmetic ingredients that offer new benefits and special effects.

[0009] To meet new consumer needs, we explored the possibility of using a known chemical phenomenon, photochromism, to break the static nature of color in our formulas, resulting in a surprising, innovative and unique product.

[0010] Photochromism is a physical phenomenon based on the reversible transition of a molecule from state A to state B upon absorption of electromagnetic radiation. The two states, A and B, are isomers in that photochemical excitation causes a rearrangement of the molecule's electronic and nuclear structure. They differ primarily in their absorption spectra. The initial stationary state, A, absorbs in the ultraviolet spectral region and is therefore usually colorless, while the higher-energy state, B, absorbs in the visible region and is strongly colored.

[0011] The word "photochromism" comes from the Greek words "phos" (light) and "chroma" (color) and means "change of color under the influence of light." Molecules capable of exhibiting this particular phenomenon are defined as "photochromic."

[0012] Such molecules find industrial applications if they meet certain requirements, such as rapid activation of the color change process (also called "switch"), high efficiency, and finally, solubility in the matrix in which they are incorporated.

[0013] Photochromic molecules such as spiropyrans and spiroxazines have been developed that change color in response to UV-A radiation, the most accessible wavelength in the solar spectrum. The high efficiency and exceptional switching speed of these compounds have made them suitable for use in the production of photochromic lenses.

[0014] The introduction of new molecules into cosmetic products is always a delicate process, as substances with low molecular weight such as these can be absorbed by the skin.

[0015] Japanese Patent Publication No. 61-275209 describes the synthesis of cosmetic compositions using polyolefin polymers in which chromophore molecules are directly linked to monomers that repeat throughout the polyolefin chain.

[0016] US Patent Publication No. 2003 / 193044 describes chromophore compositions comprising crosslinked non-cosmetic polyurethanes in which the chromophore molecules are not chemically bonded to the polymer but are merely mixed therein and are not expected to have cosmetic uses.

[0017] US Pat. No. 5,322,945 describes a method for preparing linear photochromic polysiloxanes in which chromophore molecules of the spiroxazine class are chemically bonded to monomers that repeat along the entire chain. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] Japanese Patent Application Publication No. 61-275209 [Patent Document 2] U.S. Patent Publication No. 2003 / 193044 [Patent Document 3] U.S. Patent No. 5,322,945 Summary of the Invention [Problem to be solved by the invention]

[0019] Therefore, the object of the present invention is to provide a cosmetic ingredient for cosmetics that can color and simultaneously make the cosmetic transparent in any form and under any conditions of use, and that can automatically change color when stimulated by ultraviolet light.

[0020] According to the present invention, such an object is achieved by a cosmetic ingredient having a cosmetic polymer structure as defined in claim 1.

[0021] The chromophore molecules can be of the static type, i.e., colored molecules that can remain colored, or of the dynamic photochromic type, i.e., colored molecules that can change color when stimulated by ultraviolet light, where the molecule can rapidly and reversibly switch its internal environment depending on the external environment.

[0022] The polymeric structure of the cosmetic ingredient can comprise a polyurethane-based polymer, a polysiloxane, or a linoleic acid-derived polymer that has cosmetic film-forming or emollient functionality.

[0023] The cosmetic ingredients according to the present invention allow for the production of transparent colored cosmetics that may have a fixed color or be able to change color when stimulated by ultraviolet light.

[0024] The method defined in claim 6 can be used to incorporate colored or photochromic molecules into polymers and thus into cosmetic ingredients.

[0025] In the case of photochromic molecules, to enable their insertion into the polymer, cosmetic oils (cosmetic oils) consisting of bis-hydroxyethoxypropyl dimethicone are functionalized by transesterification with the photochromic molecules, giving them the functionality necessary for immobilization on dimethicone while preserving the main cosmetic function of the cosmetic oil. Transesterification synthesis can be carried out in the presence of tin complexes at high temperatures (approximately 140°C) and without solvents.

[0026] After the photochromic molecule undergoes transesterification, the molecule itself can be used as a hydroxyl-functionalized monomer in the synthesis of polyurethanes, which can be primarily alkyl or entirely silicone. In the first case, the synthesis is carried out in accordance with EP 2349197 in the presence of diols, isocyanates, and diisocyanates of different structures (e.g., isophorone diisocyanate - IPDI, hexamethylene diisocyanate - HDI, diisocyanatodicyclohexylmethane - M12HDI, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.) commonly used in the synthesis of polyurethanes (e.g., C12-15 alkyl tartrate). In the second case, the synthesis is carried out in the presence of silicone diols commonly used in cosmetics (such as bis-hydroxyethoxypropyl dimethicone) or diisocyanates of different structures (such as isophorone diisocyanate - IPDI, hexamethylene diisocyanate - HDI, diisocyanatodicyclohexylmethane - M12HDI) according to EP 1 588 686. By appropriately modifying the functionality of the initial molecules, the monomers can be used for other types of polymers. The polymerization of polyurethanes can be carried out in the presence of tin and zinc complexes at temperatures of 90 / 95 °C.

[0027] The polymers obtained using silicone oils can be used in liquid cosmetics (e.g., lip liquids) with the secondary purpose of imparting color change functionality when exposed to UV light.

[0028] The polymers can also be incorporated into powder products (eg, eye powder) as binding oils and have a secondary color change purpose.

[0029] As an alternative to photochromic molecules, fixed color molecules (i.e., they do not change color but remain stable in their original color) available from Milliken under the name Reactint can be used, which result in colored but transparent polyurethane polymers and thus in cosmetic products with this characteristic.

[0030] A preferred example of functionalization of cosmetic silicone macrodiols with photochromic derivatives specifically designed to ensure a transition between colorless and colored states after UV irradiation is described below.

[0031] The best candidates for functionalization of macrodiols are molecules belonging to the spiropyran family, appropriately functionalized, such as the derivative FC-C3-Et, which can be obtained by the synthetic approach shown schematically below.

[0032] [ka] ["Distillazione" = distillation]

[0033] The selection of this particular structure was based on the following characteristics: A. The class of spiropyrans, typical of photochromic molecules, guarantees the required performance in terms of photochromic contrast. B. Functionalized chains inserted at the indole nitrogen allow for covalent anchoring to macrodiols via catalytic transesterification. C. The presence of nitro and methoxy groups in the phenyl residue ensures the correct position of the photoelectrostatic equilibrium both under illuminated and dark conditions, respectively, ensuring better photochemical stability.

[0034] To obtain the derivative FC-C3-Et according to the above procedure, trimethylindolenine (CAS 1640-39-7) is alkylated in the absence of solvent using an ester of a lower alcohol obtained by starting from a chain omega-bromate between C2 (ethyl bromoacetate) and C12 (e.g., ethyl 3-bromopropionate (CAS 539-74-2)). The reaction is carried out in a nitrogen atmosphere at 80-140°C for 1-48 hours. The stoichiometric ratio of indolenine to alkylating agent is 1:1 (molar) to 1:5 (molar), preferably 1:1.5.

[0035] The resulting viscous liquid is dissolved in water and extracted with CH₂Cl₂ until a colorless organic extract phase is obtained, the purpose of which is to remove excess alkylating agent.

[0036] The resulting aqueous phase is made basic (pH<12) with 5M NaOH (or other metal base) and left under stirring for 2 hours, after which it is extracted with CHCl to obtain an organic phase, which is dried over anhydrous sodium to yield a red, viscous oil consisting of a mixture of the starting indolenine and the anhydrous base. Vacuum distillation removes the indolenine to yield the pure anhydrous base as a very viscous red oil.

[0037] This is followed by the crucial condensation step of pure anhydrous base with methoxynitroresorcinaldehyde (CAS 17028-61-4): (following the synthetic approach shown in the schematic above) two different solutions of 0.5 M anhydrous base and aldehyde in absolute ethanol are prepared and preheated to 60 °C. The aldehyde solution becomes saturated at this temperature. The two solutions are rapidly mixed in a 60 °C bath and maintained at this temperature for 120 seconds. The thermostatic bath is removed and the resulting deep blue solution is left under stirring overnight. A large amount of gray precipitate is thus obtained, which is crystallized twice in absolute ethanol.

[0038] The derivative FC-C3-Et thus obtained has a melting point of about 145°C and appears as a white crystalline solid, which is highly soluble in common organic solvents: it is only partially soluble in isododecane at high temperatures.

[0039] The subsequent transesterification reaction was carried out under a variety of different experimental conditions in order to minimize the amount of organic residues present in the final functionalized macrodiol samples.

[0040] The following parameters were considered: A. Solvent B.Temperature C. Reaction time D. Catalyst type and stoichiometry E. High purity

[0041] First, the optimal transesterification catalyst was identified. Taking into account the cosmetic use of the product, a heterogeneous catalyst based on dibutyltin oxide (CAS 818-08-6) was used. This catalyst functions in a heterogeneous phase and allows filtration at the end of the reaction. All the following tests were carried out using a mass ratio of catalyst to bis-hydroxyethoxypropyl dimethicone of 1:0.0003, unless otherwise indicated.

[0042] As expected, the derivative FC-C3-Et is insoluble in neither isododecane nor pure bis-hydroxyethoxypropyl dimethicone, except at temperatures above 140 °C. Given that the melting temperature of FC-C3-Et is close to the minimum process temperature required to obtain a homogeneous solution of the photochromic in bis-hydroxyethoxypropyl dimethicone and isododecane, the reaction was initially carried out using a low-boiling solvent (below 120-130 °C). Reactions carried out in the presence of solvents are slow in both cases, making it difficult to achieve complete conversion.

[0043] Therefore, a procedure was developed that was carried out in the absence of solvent (i.e., using bis-hydroxyethoxypropyl dimethicone directly as the solvent). In this case, the reaction had to be carried out under vacuum to simultaneously distill off the ethanol released from the photochromic precursor. The distillation temperature was found to vary between 140 and 160 °C for a time range of 3 to 6 hours.

[0044] In all cases, analysis and observations in this regard also revealed a change in the bis-hydroxyethoxypropyl dimethicone alone, likely due to a transesterification reaction. In fact, both the molecular weight and viscosity of the material increased. This process is sensitive to both time and temperature.

[0045] Thus, the transesterification procedure was optimized: a suspension of 100 g of bis-hydroxyethoxypropyl dimethicone. 10 g of FC-C3-Et and 50 mg of dibutyltin oxide were placed under vacuum with vigorous stirring. The mixture was heated to approximately 145 °C, and the gradual evolution of steam (ethanol) and the gradual dissolution of the precipitate were observed. After approximately 1 hour, the suspension turned into a homogeneous solution. Heating was maintained for another 5 hours, and the reaction was monitored over time by 1H NMR spectroscopy. At the end of the reaction, the resulting blue / green oil was cooled to room temperature, diluted with 100 ml of heptane, and placed at -20 °C overnight (to precipitate the catalyst and other insoluble residues). The mixture was then filtered through a pleated filter, and the solvent was removed under reduced pressure until a constant weight was obtained. In this way, the photochromic raw material shown below as Sample I was obtained by transesterifying the derivative FC-C3-Et with cosmetic oil (bis-hydroxyethoxypropyl dimethicone).

[0046] [ka] ["catalizzatore" = catalyst]

[0047] The procedure described may include several variations, the main ones being listed below. 1. Bis-hydroxyethoxypropyl dimethicone / photochromic in a stoichiometric ratio of 1.4:1 to 50:1, preferably 10:1 (by weight). 2. Catalyst: Dibutyltin oxide or tin oxalate, using a stoichiometry of 1-0.00001% by weight relative to bis-hydroxyethoxypropyl dimethicone. 3. Temperature: 120°C to 180°C, preferably 130°C to 160°C, and more preferably 140°C to 150°C. 4. Time: 1 to 48 hours, preferably 2 to 8 hours.

[0048] The cosmetic materials or ingredients synthesized in this way can be mixed into various cosmetic compositions. The cosmetic compositions contain at least one cosmetic material or ingredient described above that functions as a cosmetic oil or film-forming oil, in a proportion ranging from 4% to 20% by weight. Furthermore, the cosmetic material or ingredient may have the ability to change color and / or be colored in a certain way.

[0049] Below are examples of different cosmetic compositions in which cosmetic oil (Sample I) is used as a binding oil in various proportions and characterized by a color change under UV light.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] [Table 4]

[0054] Furthermore, this specification reports an example of a cosmetic composition using at least one cosmetic material according to the present invention (Sample II) in a proportion of 29% by weight, which has the properties of film-forming and being colored in a certain manner.

[0055] [Table 5]

[0056] The main advantage of the present invention, which would be unexpected to one skilled in the art, is that cosmetic ingredients having the function of cosmetic oils or film-forming oils are subjected to transesterification with chromophore molecules, thereby preserving the main cosmetic function and, in the case of photochromic molecules, adding the ability to change color when the cosmetic is exposed to the ultraviolet component of solar radiation.

[0057] A clear technical advantage is that with a cosmetic formulation already optimized with a cosmetic oil or initial film-forming oil, this cosmetic formulation can easily achieve the ability to change its color upon application without altering other cosmetic performance properties (feel, sensation, staying power, etc.).

Claims

1. A cosmetic ingredient having a polymer structure for cosmetics, the polymer structure has a structure in which a cosmetic polymer and an organic photochromic molecule are chemically covalently bonded by a transesterification reaction; the cosmetic polymer is a silicone macrodiol and has emollient and / or film-forming properties; The photochromic molecule has a spiropyran-type chemical structure that can rapidly switch from one color to another, the photochromic molecule having the following structure: FC-C3-Et: 【Chemistry 1】 The cosmetic ingredient is characterized by being transparent to visible light both in a dry state and in a solution state.

2. 10. The cosmetic composition of claim 1, wherein said cosmetic polymer having emollient properties comprises a polysiloxane.

3. 3. The cosmetic ingredient of claim 2, wherein said polysiloxane is bis-hydroxyethoxypropyl dimethicone.

4. A cosmetic ingredient described in claim 2 or 3, wherein switching between the colorless state and the colored state occurs after exposure to ultraviolet light.

5. A cosmetic ingredient described in claim 4, wherein the photochromic molecule has the structure FC-C3-Et obtained as shown in the following schematic diagram. 【Chemistry 2】 ["Distillazione" = distillation]