Transparent cosmetic composition that reflects infrared radiation based on titanium dioxide flakes and its use for protecting the human epidermis against infrared radiation
This is a continuation of U.S. application Ser. No. 07/613,464, filed Nov. 13, 1990; abandoned in turn a C-I-P of Ser. No. 07/263,427 filed Oct. 27, 1988, now abandoned. 
    
    
     The present invention relates to a transparent cosmetic composition containing titanium dioxide flakes by way of a reflector of infrared radiation, as well as to the use of the said cosmetic composition for protecting the human epidermis against infrared radiation. 
     The importance of ultraviolet radiation in the tanning of the human epidermis, but also in skin ageing, and in particular that of erythemogenic UV-B rays of wavelengths between 280 and 320 nm, which are the main cause of protocarcinogenesis, is known. It has also been demonstrated recently that UV-A rays, of wavelengths between 320 and 400 nm, which cause tanning of the skin, increase the harmful effects of UV-B (The Journal of Investigative Dermatology, Vol. 59, No. 6, page 416, 1973, J. Willis, A. Kligman and J. Epstein). 
     However, solar radiation reaching the earth&#39;s surface also comprises 40% of a not insignificant radiation, namely infrared radiation, of wavelengths between approximately 760 and 2,500 nm. 
     The incidence of infrared radiation on the human epidermis is hence naturally closely linked to exposure to sun, but also to the lamps used in hairdressing salons for the natural drying of the hair, as well as to the current return of heating with wood. 
     Recent studies published by Lorraine H. KLIGMAN of the University of Pennsylvania, U.S.A, in the journal Arch. Dermatol Res. 1982, 272, pages 229-238, demonstrate that infrared radiation, although physiologically pleasant, is not harmless and that it gives rise, by itself, in the upper dermis, to a dense multiplication of fine elastic fibres resembling a nap, referred to as elaslosis, and a thickening of the fibres capable of inducing carcinogenesis. 
     Infrared radiation causes, in addition, a vasodilation and a rise in the skin temperature, resulting in a skin erythema designated &#34;erythema ab igne&#34; in L.H. Kligman&#39;s publication. 
     It has hence proved especially advantageous to reflect the infrared radiation in order to atteruate its harmful effects on the human epidermis. 
     The property of reflecting natural radiation, possessed by certain opaque pigments, is known. Among these pigments, metal salt and oxide powders, such as titanium dioxide and zinc oxide powders, may be mentioned by way of example. 
     However, when used as reflecting agents in cosmetic compositions that protect the human epidermis, metal salt and oxide powders have the drawback of forming an unattractive white film on the skin. 
     The Applicant has hence performed many investigations for the purposes of discovering new substances which, while reflecting to a substantial extent the infrared radiation capable of damaging the human epidermis, also make it possible, when they are introduced into a cosmetic vehicle suitable for easy application on the human epidermis, to obtain transparent protective cosmetic compositions which, after application, do not leave a white film, disliked by the user, remaining on the skin, which are not sticky to the touch and which show good adhesion to the skin as well as good chemical and photochemical stability. 
     The Applicant has thus discovered that a certain substance, despersible in the cosmetic medium in which it is used, possessing a reflectance (R) of infrared radiation equal to at least 45%, and preferably to 55%, and of which a 2% strength dispersion in vaseline possesses an optical transmission in visible light of at least 85%, and preferably at least 90%, could, surprisingly, when incorporated in a cosmetic composition in an amount of less than 10% by weight, both reflect infrared radiation to a substantial extent and endow the cosmetic composition containing it with the desired advantageous properties stated above, and especially transparency on the human epidermis, good adhesion to the skin and good chemical and photochemical stability, as well as an effect of attenuation of the erythema &#34;ab igne&#34; caused by infrared radiation. This substance consists of titanium dioxide flakes having dimensions between 1.5 and 25 microns. 
     The subject of the invention is hence a transparent cosmetic composition that reflects infrared radiation, comprising 0.5 to 10% by weight of titanium dioxide flakes having dimensions between 1.5 and 25 microns. 
     The subject of the invention is, in addition, a process for protecting the human epidermis against infrared radiation, consisting in applying on the skin a sufficient amount of a transparent cosmetic composition as defined above. 
     According to a preferred embodiment, the transparent cosmetic composition according to the invention contains 1 to 5% by weight of titanium dioxide flakes of dimensions between 1.5 and 25 microns, by way of an infrared-reflecting agent. 
     According to a more especially preferred embodiment, it contains 1 to 3% by weight of this infrared-reflecting agent. 
     An especially preferred infrared-reflecting agent for use according to the invention consists of titanium dioxide flakes of size 2 to 20 microns over a thickness of 0.4 to 1 micron, sold by the company SUMITOMO Chem. Co. under the name &#34;LUXELEN SILK D&#34;. 
     The higher the reflectance (R) of the infrared-reflecting agent, the more effective the latter. 
     The reflectance is the ratio between the intensity of the reflected flux and the intensity of the incidence flux. This measurement is performed in the wavelength region ranging from 1,100 to 2,500 nm, using an apparatus known as &#34;Infra-alyseur&#34;. 
     The optical transmission in the visible of a 2% strength dispersion of reflecting agent in vaseline is measured by means of a spectrophotometer with an integration sphere in the wavelength region ranging from 400 to 700 nm, using thin, approximately 10μ, layers. 
     The optical transmission is the ratio between the intensity of the transmitted flux and the intensity of the incident flux. 
     The cosmetic composition containing the infrared-reflecting agent according to the invention can also contain agents that screen ultraviolet radiation which are well known in the prior art and compatible with the infrared-reflecting agent used according to the invention. These agents that screen ultraviolet radiation can be tipid-soluble or water-soluble UV-A, UV-B or broadband screening agents. 
     They are present in the cosmetic compositions according to the invention in proportions of between 0.5 and 20% by weight relative to the total weight of the composition. 
     By way of UV screening agents capable of being used in the transparent cosmetic composition according to the invention, the following compounds may be mentioned, this list not being limitative: 
     para-aminobenzoic acid, its esters and derivatives such as: 
     Ethyl N,N-dihydroxypropyl-para-aminobenzoate 
     Ethyl N-ethoxy-para-aminobenzoate 
     Ethyl para-cimethylaminobenzoate 
     Amyl para-dimethylaminobenzoate 
     Glyceryl para-aminobenzoate 
     Butyl para-dimethylaminobenzoate 
     2-Ethylhexyl para-dimethylaminobenzoate 
     the following salicylates: 
     Potassium on triethanclamine salicylate 
     Amyl salicylate 
     Menthyl salicylate 
     Homomenthyl salicylate 
     2-Ethylhexyl salicylate 
     Phenyl salicylate 
     Benzyl salicylate 
     para-Isopropanolphenyl salicylate 
     Isodecyl salicylate 
     Homomenthyl N-acetylanthranilate 
     The following cinnamates and cinnamic acid derivatives: 
     Potassium cinnamate 
     Octyl cinnamate 
     Ethyl 4-isopropyl cinnamate 
     Ethyl 2,4-diisopropyl cinnamate 
     Methy 2,4-diisopropyl cinnamate 
     para-Methoxycinnamic acid and its salts 
     Propyl para-methoxy cinnamate 
     Isopropyl para-methoxy cinnamate 
     Isoamyl para-methoxy cinnamate 
     2-Ethylhexyl para-methoxy cinnamate 
     2-Ethoxyethyl para-methoxy cinnamate 
     Cyclohexyl para-methoxy cinnamate 
     Ethyl α-cyano-β-phenyl cinnamate 
     2-Ethylhexyl α-cyano-β-phenyl cinnamate 
     The following benzophenones: 
     2,4-Dihydroxybenzophenone 
     2,2&#39;-Dihydroxy-4-methoxybenzophenone 
     2,2&#39;-Dihydroxy-4,4&#39;-dimethoxybenzophenone 
     2,2&#39;-Dihydroxy-4,4&#39;-dimethoxybenzophenone-5-sulphonic acid and its salts 
     2,2&#39;,4,4&#39;-Tetrahydroxybenzophenone 
     2-Hydroxy-4-methoxybenzophenone 
     2-Hydroxy-4-methoxy-4&#39;-methylbenzophenone 
     2-Hydroxy-4-methoxybenzophenone-5-sulphonic acid and its salts 
     4-Phenylbenzophenone 
     2-Ethylhexyl 4&#39;-phenylbenzophenone-2-carboxylate 
     2-Hydroxy-4-n-octyloxybenzophenone 
     4-Hydroxy-3-benzophenonecarboxylic acid and its salts 
     2-Phenylbenzimidazole-5-sulphonic acid and its salts 
     Urocanic acid and its salts 
     Ethyl urocanate 
     2-Phenyl-5-methylbenzoxazole 
     2-(2&#39;-Hydroxy-5&#39;-methylpheryl)benzotriazole 
     2-(2&#39;-Hydroxy-5&#39;-tert-octylphenyl)benzotriazole 
     Sodium 3,4-dimethoxyphenylglyoxylate 
     Dibenzalazine 
     Dianisoylmethane 
     4-Isopropyldibenzoylmethane 
     4-tert-Butyl-4&#39;-methoxydibenzoylmethane 
     3-Berzylidene-dl-camphor 
     3-(4&#39;-Methylbenzylidene)-dl-camphor 
     3-(4&#39;-Sulphotenzylidene)camphoric acid and its salts (French Patent 2,282,426) 
     3-(3&#39;-Sulpho-4&#39;-mathylbenzylidere)camphoric acid and its salts (French Patent 2,236,515) 
     4-(2-Oxc-3-bornylidenemethyl)phenyltrimethylammonium methyl sulphate (French Patent 2,199,971) 
     Methyleugenol 
     Guanine 
     Digalloyl trioleate 
     5-(3,3-Dimethyl-2-norbornylidene)-3-penten-2-one 
     Benzene-1,4-bis(3-methylidene-10-camphorsulphonic) acid and its salts (French Patent 2,528,420) 
     N-(2-Ethylnexyl)-4-(3&#39;-methylidenecamphor)benzenesulphonamide (French Patent 2,529,887) 
     N-(2-Ethylhexyl)-3-[(3&#39;-methoxy-4&#39;-n-butoxy)benzylidene]-10-camphorsulphonamide (French Patent 2,529,887) 
     N-(2-Ethylhexyl)-3-benzylidene-10-camphorsulphonamide (French Patent 2,529,887) 
     the homopolymer of 3-[4&#39;-(acrylamidomethyl)benzylidene]-dl-camphor of MW less than 20,000 (French Patent 2,601,365) 
     the copolymer of 2-[(2&#39;-hydroxy-5&#39;-tert-octyl)phenyl]-2 H-benzotriazole and butyl vinyl ether (French Patent 2,601,365) 
     One or more of the following benzylidenecamphor derivatives is/are preferably used by way of UV screening agents: 
     3-Benzylidene-dl-camphor 
     3-(4&#39;-Methylbenzylidene)-dl-camphor 
     3-(4&#39;-Sulphobenzylidene)camphonic acid and its salts 
     3-(3&#39;-Sulpho-4&#39;-methylbenzylidene)camphoric acid and its salts 
     4-(2-Oxo-3-bornylidenemethyl)phenyltrimethylammonium methyl sulphate 
     Benzene-1,4-bis(3-methylidene-10-camphorsulphonic) acid and its salts 
     N-(2-Ethylnexyl)-4-(3&#39;-methylidenecamphor)benzenesulphonamide 
     N-(2-Ethylrexyl)-3-[(3&#39;-methoxy-4&#39;-n-butoxy)benzylidene]-10-camphorsulphonamide 
     N-(2-Ethylhexyl)-3-benzylidene-10-camphorsulphonamide 
     homopolymer of 3-[4&#39;-(acrylamidomethyl)benzylidene]-dl-camphor of MW less than 20,000 
     copolymer of 2-[(2&#39;-hydroxy-5&#39;-tert-octyl)phenyl]-2 H-benzotriazole and butyl vinyl ether. 
     The cosmetic composition according to the invention may be presented in the form of a suspension or dispersion in solvents or fats, in the form of an emulsion such as a cream or a milk, or in the form of an ointment, a gel or a solid stick, or may be packaged as an aerosol and be presented in the form of a foam. 
     The pH of the cosmetic composition of the invention is lower than or equal to 7.5 and preferably lower than or equal to 7.0. 
     It can contain the cosmetic adjuvants usual in this type of composition, such as thickeners, emollients, moisturizing products, surfactants, preservatives, sequestering agents, antioxidants, artifoams, oils, waxes, lanolin, perfumes, propellents, colorants, vitamins or any other ingredient customarily used in cosmetics. 
     In the case of a composition packaged as an aerosol, traditional propellents such as alkanes, fluoroalkanes and chlorofluoroalkanes are used. 
     Among the main adjuvants capable of being present in the cosmetic compositions of the invention, there may be mentioned solvents such as water and lower monohydric alcohols or polyols containing 1 to 6 carbon atoms, or mixtures thereof, especially preferred monohydric alcohols or polyols being ethanol, isopropanol, propylene glycol, glycerin and sorbitol; there may also be mentioned fats such as mineral, animal, vegetable or synthetic oils or waxes, fatty acids, fatty acid esters such as triglycerides of fatty acids having from 6 to 12 carbon atoms, fatty alcohols, vaseline, paraffin, lanolin, hydrogenated lanolin, acetylated lanolin and silicone oil. 
     An embodiment of the invention is an emulsion in the form of a cream or milk comprising, in addition to the infrared-reflecting agent, fatty alcohols, fatty acid esters and in particular fatty acid triglycerides, fatty acids, lanolin and its derivatives, natural or synthetic oils or waxes, and emulsifiers, in the presence of water. 
     A preferred embodiment of the invention is a water-in-oil type emulsion. 
     An emulsion of this kind contains an aqueous phase, a fatty phase and an emulsifying system. 
     In this type of emulsion, the concentration of emulsifying system is between 4 and 35% relative to the total weight of the emulsion; the fatty phase is present in proportions of between 20 and 60% and the aqueous phase in proportions of between 20 and 70%, relative to the total weight of the emulsion. The emulsifiers are those customarily used in this type of emulsion. They are more especially chosen from: 
     fatty acid (C 12  -C 18 ) esters of sorbitan; 
     esters of hydroxystearic acid and fatty alcohols (C 12  -C 30 ); 
     mono- and diesters of fatty acids (C 12  -C 18 ) and glycerol or polyglycerol; 
     condensates of ethylene oxide with propylene glycols; 
     oxypropylenated/oxyethylenated fatty alcohols (C 12  -C 20 ); 
     polycyclic alcohols such as sterols; 
     high molecular weight aliphatic alcohols such as lanolin; 
     mixtures of oxypropylenated/polyglycerolated alcohols and magnesium isostearate; 
     succinic esters of polyoxyethylenated or polyoxypropylenated fatty alcohols; and 
     mixtures of magnesium lanolate, calcium lanolate, lithium lanolate, zinc lanolate or aluminium lanolate and lanolin alcohol or hydrogenated lanolin. 
     Among fatty products forming the fatty phase of the emulsions, there may be mentioned: 
     hydrocarbon oils such as paraffin oil, purcellin oil, perhydrosqualene and solutions of microcrystalline waxes in oils, 
     animal or vegetable oils such as sweet almond oil, avocado oil, oil of catophyllum, lanolin and its derivatives, castor oil, caballine oil, pig oil, sesame oil, olive oil, jojoba oil, shea oil, hoplostethus oil, 
     mineral oils whose initial distillation point at atmospheric pressure is approximately 250° C. and whose final point is of the order of 410° C., such as liquid paraffin, 
     saturated or unsaturated fatty acid esters, such as alkyl myristaces, such as isopropyl, butyl or cetyl myristate, hexadecyl stearate, ethyl or isopropyl palmitates, triglycerides of octanoic and decanoic acids and cetyl ricinoleate. 
     The fatty phase can also contain silicone oils which are soluble in other oils, such as dimethylpolysiloxane, methylphenylpolysiloxane and silicone/glycol copolymer, fatty acids and fatty alcohols. 
     For the purpose of promoting oil retention, it is also possible to use waxes such as carnauba wax, candelilla wax, beeswax, microcrystalline wax, ozokerite and Ca, Mg and Al oleates, myristates, linoleates and stearates. 
     The emulsions of the water-in-oil type may also be presented in the form of sun sticks. In this case, the concentration of the aqueous phase in the emulsion is generally between 5 and 70% by weight, relative to the total weight of the emulsion. 
     In general, these water-in-oil emulsions are prepared by introducing the fatty phase and the emulsifier into the manufacturing tank. The mixture is heated to a temperature of 70°-75° C. The oil-soluble ingredients are then added, after which the water, brought before-hard to the same temperature, in which the watersoluble ingredients have been dissolved beforehand is added with stirring; the mixture is stirred until an emulsion having the desired fineness is obtained, and then allowed to cool to room temperature, optionally with slow stirring. 
     The fatty gels comprise an oil or wax and a thickener such as silica. The oleo-alcoholic or aqueous-alcoholic gels comprise one or more lower alcohols or polyols such as ethanol, propylene glycol or glycerin, a thickener such as silica, cellulose derivatives, polyacrylic acid derivatives, and guar, carob and xanthan gums, in the presence of oil or water, respectively. 
     The solid sticks consist of fats such as natural or synthetic waxes and oils, fatty alcohols, fatty acid esters and lanolin. 
     The examples which follow are designed to illustrate the invention, no limitation of the latter being implied. 
    
    
     EXAMPLE 1 
     A cream that protects the human epidermis is prepared in the form of a water-in-oil emulsion of the following composition: 
     
         ______________________________________                                    
2-Octyl-1-dodecanol      10       g                                       
Magnesium stearate       4        g                                       
Beeswax                  5        g                                       
Hydrogenated Lanolin     1        g                                       
Lanolin                  4        g                                       
Sorbitan sesquioleate sold by the company                                 
                         4.5      g                                       
ICI under the name &#34;ARLACEL 83&#34;                                           
Mixture of glycerol mono- and distearate                                  
                         1        g                                       
and potassium stearate                                                    
Liquid paraffin          27       g                                       
Titanium dioxide flakes sold by the company                               
                         2        g                                       
SUMITONO under the name &#34;LUXELEN SILK                                     
D&#34;                                                                        
Imidazolidinylurea derivative sold by the                                 
                         0.2      g                                       
company SUTTON Labs under the name                                        
&#34;GERMALL 115&#34;                                                             
Perfume                  qs                                               
Water                    qs 100   g                                       
______________________________________                                    
 
    
     This cream is prepared according to traditional techniques for preparing emulsions, by dispersing the infrared-reflecting agent in the fats and the emulsifiers, heating this fatty phase to about 70°-75° C. and adding the water, also heated to 70°-75° C., with brisk stirring; stirring is maintained for 10 to 15 minutes, the mixture is then allowed to cool with moderate stirring and, at about 40° C., perfume and preservative are added. 
     EXAMPLE 2 
     A gel is prepared which is transparent on the skin, having the following composition: 
     
         ______________________________________                                    
Titanium dioxide flakes sold by the company                               
                          2        g                                      
SUMITOMO under the name &#34;LUXELEN SILK                                     
D&#34;                                                                        
2-Hydroxy-4-methoxybenzophenone-5-sulphonic                               
                          0.5      g                                      
acid (BASF &#34;UVINUL MS 40&#34;)                                                
Crosslinked polyacrylic acid, MW 4,000,000,                               
                          0.5      g                                      
sold by the company GOODRICH under the                                    
name &#34;CARBOPOL 940&#34;                                                       
Propylene glycol          30       g                                      
Triethanolamine           0.91     g                                      
Sequestering agent, preservative, perfume                                 
                          qs                                              
Water                     qs 100   9                                      
______________________________________                                    
 
    
     EXAMPLE 3 
     A cream (oil-in-water emulsion) having the following composition is prepared: 
     
         ______________________________________                                    
Mixture of cetyl/stearyl alcohol and cetyl/                               
                          7        g                                      
stearyl alcohol oxyethylenated with 33 moles                              
of ethylene oxide, sold by the company                                    
HENKEL under the name &#34;SINNOWAX AO&#34;                                       
Mixture of non-self-emulsifying glycerol                                  
                          2        g                                      
mono- and distearate                                                      
Cetyl alcohol             1.5      g                                      
Silicone oil              1.5      g                                      
Liquid paraffin           15       g                                      
4-(2-Oxo-3-bornylidenemethyl)phenyltri-                                   
                          2        g                                      
methylammonium methyl sulphate, prepared                                  
according to Example 1 of French Patent                                   
2,199,971                                                                 
Sodium Lactate            1        g                                      
Titanium dioxide flakes sold by the company                               
                          2        g                                      
SUMITOMO under the name &#34;LUXELEN SILK                                     
D&#34;                                                                        
Glycerin                  20       g                                      
Preservative, perfume     qs                                              
Water                     qs 100   g                                      
______________________________________                                    
 
    
     The &#34;LUXELEN SILK D&#34; is dispersed in the fatty phase containing the emulsifier. The aqueous phase containing the water, the glycerin, the sodium lactate and the 4-(2-oxo-3-bornylidenemethyl)phenyltrimethylammonium methyl sulphate is heated to 70°-75° C. The fatty phase, heated beforehand to 70°-75° C., is added with brisk stirring to the aqueous phase, and the mixture is then left to cool with moderate stirring; perform and preservative are added at about 40° C. 
     EXAMPLE 4 
     A cream (water-in-oil emulsion) having the following composition is prepared: 
     
         ______________________________________                                    
Liquid paraffin            5       g                                      
White vaseline             21      g                                      
Sunflower oil              4       g                                      
Shea butter                1.5     g                                      
Ester of hydroxyoctacosanyl alcohol and                                   
                           7       g                                      
hydroxystearic acid, sold by the company                                  
AKZO CHEMIE under the name &#34;ELFACOS C                                     
26&#34;                                                                       
Triglyceryl diisostearate sold by the company                             
                           5.5     g                                      
HENKEL under the name &#34;LAMEFORM TG1&#34;                                      
Isostearic acid diethanolamide sold by the                                
                           3.5     g                                      
company HENKEL under the name                                             
&#34;LAMEFORM GE 2&#34;                                                           
Cetyl alcohol              4       g                                      
3-(4&#39;-Methylbenzylidene)-dl-camphor                                       
                           2.5     g                                      
(MERCK &#34;EUSOLEX 6300&#34;)                                                    
Propylene glycol           2       g                                      
Titanium dioxide flakes sold by the company                               
                           2.5     g                                      
SUMITOMO under the name &#34;LUXELEN SILK                                     
D&#34;                                                                        
Antioxidant                0.05    g                                      
Preservatives, perfume     qs                                             
Water                      qs 100  g                                      
______________________________________