Patent Application
20130189204
The invention relates to a high Sun Protection Factor (SPF)/UV-A Protection Factor (UVAPF) sunscreen composition.
Solar radiation includes about 5% ultraviolet (UV) radiation, wavelength of which is between 200 nm and 400 nm. It is further classified into three regions: from 320 to 400 nm (UV-A), 290 to 320 nm (UV-B) and from 200 to 290 nm (UV-C). A large part of UV-C radiation is absorbed by the ozone layer. Scientific studies have indicated that exposure to UV-A and UV-B radiation for short period causes reddening of the skin and localized irritation, whereas continued and prolonged exposure can lead to sunburn, melanoma and formation of wrinkles. It is also reported that UV radiation causes significant damage to hair. Therefore, it is desirable to protect the skin and other keratinous substrates of the human body from the harmful effects of both, UV-A and UV-B radiation.
Various cosmetic preparations have been reported for preventing and/or protecting the skin from harmful effects of ultraviolet radiation. Numerous organic sunscreen agents capable of absorbing UV-A rays are reported in the field of cosmetics amongst which a particularly useful sunscreen is of the dibenzoylmethane class. Many UV-B sunscreens are also known and approved for safe use in personal care compositions for protection from UV-B radiation. Many cosmetic manufacturers prefer to include both UV-A and UV-B sunscreens in photoprotective compositions so as to provide protection over the entire range of UV radiation. Sun protection Factor (SPF) and UV-A protection factor (UVAPF) are commonly measured attributes of photoprotective compositions which indicate the protection that the skin gets from exposure to both UV-B and UV-A radiation.
Thus, cosmetic manufacturers try to provide consumers with products having higher and higher SPF/UVAPF. One of the ways of achieving this is to incorporate high levels of UV-A and UV-B sunscreens. One disadvantage of this approach is the high cost associated with incorporation of high levels of sunscreens which are expensive. Further, there are safety and regulatory limitations on the upper limit of incorporation of these sunscreens. Sensory properties are also reported to get affected on incorporation of high levels of sunscreens. Hence, there is a problem of achieving high SPF/UVAPF while keeping the total amount of sunscreens in the compositions relatively low.
Various publications on more effective sunscreen compositions have been reported. One such patent publication is US 2005/0063925 which discloses an oil-in-water photoprotective emulsion containing Gemini surfactants and associative polymers. The Gemini surfactant is used as an emulsifier which has at least one dimeric surfactant comprising two surfactant units, which may be identical or different, each consisting of a hydrophilic head and a hydrophobic tail and connected to each other, via the hydrophilic heads, by means of a spacer group. Further, this composition comprises at least one photoprotective system capable of screening out UV rays, containing at least one mineral nanopigment based on metal oxide, and optionally at least one organic, preferably hydrosoluble or liposoluble UV-A and/or UV-B screening agent, and at least one associative polymer comprising at least one C8-C40 fatty chain.
JP 2008 162 930 (Shiseido) discloses a oil-in-water type emulsion sunscreening cosmetic comprising (a) an oil-soluble ultraviolet absorber (b) a water-soluble thickener (e.g. acrylic water-soluble polymer), (c) a water-soluble ultraviolet absorber and (d) one or more kinds of hydrophilic nonionic surfactant selected from the group consisting of a fatty acid-PEG-glyceryl-based surfactant, a hydrogenated castor oil-based surfactant and a PEG-PPG alkyl ether-based surfactant.
WO 2008/022946 (Unilever) discloses that cosmetic compositions comprising dibenzoylmethane or its derivative and p-methoxycinnamic acid or its derivative can be stabilized by incorporating a combination of fatty alcohol ethoxylates and polyalkyleneglycol.
These publications are targeted to ensuring stability of the formulation while having the desired photoprotection and is not reported to enhance SPF/UVAPF. Any attempt at increasing the SPF/UVAPF has been with the use of high amounts of sunscreen compounds.
Therefore there exists a need for a personal care composition comprising sunscreen agents preferably in low concentrations that are able to provide much higher SPF/UVAPF values as compared to known sunscreen compositions comprising such low levels of sunscreen agents. It is desirable, if the enhanced SPF/UVAPF benefit could be achieved through synergistic interaction of commonly used ingredients, thereby giving the desired photoprotection benefits at substantially low costs.
The present inventors have been working on solving this problem and have surprisingly found that cosmetic compositions comprising dibenzoylmethane or its derivative and optionally an oil soluble UV-B sunscreen when incorporated in a sunscreen composition along with a non-ionic surfactant of a select class along with a polymer of a select class or a select fatty acid, provides the enhanced SPF/UVAPF benefits while maintaining the desired sensorial properties when applied on the substrate of interest.
It is therefore an object of the present invention to obviate at least some drawbacks of the prior art and provide high SPF/UVAPF photo-protective sunscreen composition.
Another object of the present invention is to provide high SPF/UVAPF sunscreen composition without compromising on the desired skin sensorial properties.
Yet another object of the present invention is to achieve the above objects using relatively low amounts of sunscreen agents thereby keeping costs low.
According to the first aspect of the present invention there is provided a high SPF and/or UVAPF solid sunscreen composition comprising less than 8% total organic sunscreens, the composition comprising,
The composition of the first aspect of the invention is preferably a cream.
According to the second aspect of the invention there is provided a high SPF and/or UVAPF non-solid sunscreen composition comprising less than 8% total organic sunscreens, the composition comprising,
The composition of the second aspect of the invention is preferably a lotion.
These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format “from x to y” are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format “from x to y”, it is understood that all ranges combining the different endpoints are also contemplated.
By “A Sunscreen Composition” as used herein, is meant to include a composition for topical application to sun-exposed areas of the skin and/or hair of mammals, especially humans. Such a composition may be generally classified as leave-on or rinse off, and includes any product applied to a human body for also improving appearance, cleansing, odor control or general aesthetics. The composition of the present invention can be in the form of a liquid, lotion, cream, foam, scrub, gel, soap bar or toner, or applied with an implement or via a face mask, pad or patch. Non-limiting examples of such sunscreen compositions include leave-on skin lotions, creams, antiperspirants, deodorants, lipsticks, foundations, mascara, sunless tanners and sunscreen lotions and wash-off shampoos, conditioners, shower gels, toilet bars. “Skin” as used herein is meant to include skin on the face and body (e.g., neck, chest, back, arms, underarms, hands, legs, buttocks and scalp) and especially to the sun exposed parts thereof. The composition of the invention is also of relevance to applications on any other keratinous substrates of the human body other than skin e.g. hair where products may be formulated with specific aim of providing photoprotection.
The first aspect of the invention provides for a solid sunscreen composition. By a solid sunscreen composition is meant a composition that has a critical shear stress (apparent yield stress) as defined by H A Barnes (Handbook of Elementary Rheology, University of Wales Aberystwyth, 71-73 (2000)) of higher than 20 Pa, preferably higher than 50 Pa at 25° C. It is preferred that the solid composition has an apparent yield stress of less than 10 000 Pa at 25° C. It is preferred that the viscosity of solid compositions of the invention at critical shear stress is in the range of 1 000 to 500 000 Pa·s, preferably 1 000 to 100 000 Pa·s at 25° C. A preferred solid composition is a cream. Creams are usually known as soft solids. Thus, by the use of the term solid composition, in the present invention, are included soft-solid compositions.
The second aspect of the invention provides for a non-solid sunscreen composition. By a non-solid sunscreen composition is meant a composition that has a critical shear stress (apparent yield stress) of less than 100 Pa, preferably less than 20 Pa to 25° C. The apparent yield stress is preferably at least 5 Pa at 25° C. It is preferred that the non-solid composition has a viscosity at critical shear stress of less 1000 Pa·s at 25° C. A preferred non-solid composition is a lotion.
Definitions of lotion and cream have been given by Brummer (Rheology Essentials of Cosmetic and Food Emulsions, Springer-Verlag Berline Heidelberg, 81-83 (2006)). Therein creams are defined as those compositions which do not flow out from a container at 25° C. when it is turned upside down. Lotions are those compositions which flow out from the container at 25° C. when turned upside down.
By ‘A High SPF sunscreen composition’ is meant a composition that has an SPF equal to or higher than 15, preferably more than 20, more preferably higher than 25. By ‘A High UVAPF sunscreen composition’ is meant a composition that has a UVAPF equal to or higher than 4, preferably higher than 8.
The SPF and UVAPF are measured using the standard protocols ISO/WD 4445 and ISO/CD 24443 respectively.
It is preferred that high SPF/UVAPF is achieved using total UV-B sunscreens in the range of 0.1 to 6%, preferably from 0.5 to 6% by weight of the composition. It is an advantage of the present invention that the high SPF/UVAPF values are achieved by using low amount of total organic sunscreens. By low amount of total organic sunscreens is meant that the total amount of organic sunscreens is less then 8%, preferably less than 7%, further more preferably less than 6% by weight of the composition.
The composition of the invention comprises 0.1 to 5% dibenzoylmethane or its derivative. Preferred dibenzoylmethane derivative are selected from 4-tert-butyl-4′-methoxydibenzoylmethane, 2-methyldibenzoylmethane, 4-methyl-dibenzoyl-ethane, 4-isopropyldibenzoyl-methane, 4-tert-butyldibenzoylmethane, 2,4-dimethyldibenzoylmethane, 2,5-dimethyldibenzoylmethane, 4,4′-diisopropyl-dibenzoylmethane, 2-methyl-5-isopropyl-4′-methoxydibenzoylmethane, 2-methyl-5-tert-butyl-4′-methoxy-dibenzoyl methane, 2,4-dimethyl-4′-methoxy dibenzoylmethane or 2,6-dimethyl-4-tert-butyl-4′-methoxy-dibenzoylmethane. The most preferred dibenzoylmethane derivative is 4-tert.-butyl-4′-methoxydibenzoylmethane. Dibenzoylmethane or its derivative is preferably present in 0.2 to 5%, more preferably 0.4 to 4%, by weight of the composition.
The composition of the invention preferably comprises 0.1 to 7%, preferably from 0.5 to 6% an oil soluble UV-B organic sunscreen by weight of the composition. The oil soluble UV-B organic sunscreen is preferably selected from the class of cinnamic acid, salicylic acid, diphenyl acrylic acid or derivatives thereof. A few of the preferred oil soluble UV-B sunscreens which are commercially available and useful for inclusion in the composition of the invention are Octisalate™ (octyl salicylate), Homosalate™ (3,3,5-trimethyleyclohexyl 2-hydroxybenzoate), Neo Heliopan™ (a range of organic UV filters including ethylhexyl methoxycinnamate (Neo Heliopan AV) and ethylhexyl salicylate (Neo Heliopan OS)), Octocrylene™ (2-ethylhexyl 2-cyano-3,3-diphenyl-2-propenoate) or Parsol MCX™ (2-ethylhexyl-4-methoxycinnamate). According to a particularly preferred aspect of the invention the oil soluble UVB sunscreen is 2-ethylhexyl-4-methoxycinnamate. According to another particularly preferred aspect of the invention the oil soluble UVB sunscreen is 2-ethylhexyl 2-cyano-3,3-diphenyl-2-propenoate. It is interesting to note that only use of oil soluble UV-B sunscreens in the composition of the present invention provide the enhanced SPF/UVAPF benefits of the invention while water-soluble UV-B sunscreens do not provide the desired benefits. It is preferred that the composition of the invention is substantially free of water soluble organic sunscreens. Water soluble sunscreens may however be incorporated in small amount, preferably less than 2%, further more preferably less than 1%, and optimally absent from the composition of the invention.
An especially preferred oil soluble UVB sunscreen is 2-ethylhexyl 2-cyano-3,3-diphenyl-2-propenoate which is commercially available as Octocrylene™.
An important ingredient that contributes to enhancement of SPF/UVAPF of the sunscreen composition of the invention is a selective class of non-ionic surfactant. The non-ionic surfactant is selected from the class of ethoxylates of fatty alcohol/fatty acids with saturated carbon chain and having HLB greater than 15.5 or from the class of ethoxylates of fatty alcohol/fatty acids with unsaturated carbon chain with HLB greater than 12. It is observed that use of ionic surfactants or non-ionic surfactants of the fatty alcohol/fatty acid ethoxylate class not meeting the claimed criteria do not provide the desired SPF/UVAPF enhancement. HLB is calculated using the Griffin method wherein HLB=20×Mh/M wherein Mh is the molecular mass of the hydrophilic portion of the molecule and M is the molecular mass of the whole molecule, giving a result on an arbitrary scale of 0 to 20. Typical values for various surfactants are given below:
Ethoxylates of fatty alcohol (usually available under the Brij class) have the structure:
where R is a group consisting of carbon chain of 2 to 24; and R1 is alkyl or H.
Ethoxylates of the fatty acid (usually available under the Myrj class) have the structure:
where R is a group consisting of carbon chain of 2 to 24.
Suitable examples of commercially available non-ionic surfactants for use in the composition of the invention are Brij 35 (also known as Laureth-23 or HO—(C2H4O)23C12H25 or polyoxyethylene lauryl ether (a C12EO23 compound)), Brij 97 (also known as Oleth-10 or HO—(C2H4O)10C18H35 or polyoxyethylene 10 oleyl ether (unsaturated C18EO10)), Brij 700 (also known as steareth-100 or polyoxyethylene (100) stearyl ether (C18EO100)), Brij 99 (polyoxyethylene (20) oleyl ether (unsaturated C18EO20)), Myrj S40 (PEG-40 stearate), Myrj S50 (PEG-50 stearate), or Myrj 59 (PEG-100 stearate). The non-ionic surfactant is included in 0.1 to 5%, preferably 0.5 to 4%, by weight of the composition.
Suitable polymers of the class of acrylate/R-methacrylate copolymer or crosspolymer, or an acrylate/R-alkyl acrylate crosspolymer, wherein R and alkyl are C10-30 alkyl groups, include: (i) Acrylate/Beheneth-25 Methacrylate Copolymer, (ii) Acrylate/Steareth-20 Methacrylate Copolymer, (iii) Acrylate/Steareth-20 Methacrylate Crosspolymer, or (iv) Acrylates/C10-30 Alkyl Acrylate Crosspolymer.
R-methacrylate copolymer or crosspolymer has the general structure:
—(CH2—CMeCO2H)m—(CH2—CO2R)n—
R-alkyl acrylate crosspolymer has the general structure:
—(CH2—CAlkylCO2H)m—(CH2—CO2R)n—
wherein m and n are any whole integers in the range 500-10 000 000, preferably 500-1 000 000, most preferably 500-500 000.
Commercially available polymers useful for inclusion in the composition of the invention are Aculyn™ 22, Aculyn™ 28, or Aculyn™ 88, which are available from Rohm and Haas or Pemulen TR-2 which is available from Lubrizol.
Commercially available polymers of the class of copolymers of acryloyldimethyltaurate with vinyl pyrrolidone, methacrylate or R-alkyl acrylate include Aristoflex AVC™, Aristoflex HMB™, Aristoflex BLV™, Aristoflex AVS™ available from Clariant. When included, polymers from the above classes give the benefits of the invention at more than 0.2% up to 0.5% by weight of the composition.
Not wishing to be bound by theory, it is observed that inclusion of the specific non-ionic surfactant meeting the above criterion in the solid compositions of the invention provides the desired SPF/UVAPF enhancement, but adversely affects the sensory properties of the solid product when applied on the skin. It is only with inclusion of the polymers meeting the above criterion that the sensory properties are attained while maintaining the high SPF/UVAPF values. When polymers, not meeting the above criterion, are used, either the desired sensory properties are not achieved or the SPF/UVAPF enhancement is not attained.
The composition of the invention comprises a cosmetically acceptable base. The cosmetically acceptable bases are such as to have a product in preferably a cream, lotion, gel or emulsion format. A preferred format for the solid form of the composition is a cream, further more preferably one which has a vanishing cream base. Vanishing cream base is one which comprises 3 to 25% w/w fatty acid. Optionally, the composition may comprise 0.1 to 10% soap.
When included, the fatty acid is preferably a C10 to C22 fatty acid, more preferably a C16 to C18 fatty acid. Most preferably the fatty acids are stearic acid or palmitic acid or a mixture thereof and the soap is preferably the potassium salt of the fatty acid mixture. The fatty acid is often hystric acid which is substantially (generally about 90 to 95%) a mixture of 45% stearic acid and 55% palmitic acid. Thus, inclusion of hystric acid and its soap to prepare compositions of the invention is within the scope of the present invention. It is particularly preferred that the composition comprises higher than 5%, preferably higher than 7%, more preferably higher than 10% fatty acid. It has been observed that use of such high levels of fatty acid also contributes to the high SPF/UVAPF. The cosmetically acceptable base is usually from 10 to 99.9%, preferably from 50 to 99% by weight of the composition. The cosmetically acceptable base preferably includes water. Water is preferably included in 35 to 90%, more preferably 50 to 85%, further more preferably 50 to 80% by weight of the composition.
Other useful sun-protective agents e.g. inorganic sunblocks may be preferably used in the present invention. These include, for example, zinc oxide, iron oxide, silica, such as fumed silica, or titanium dioxide. The total amount of sun block that is preferably incorporated in the composition according to the invention is from 0.1 to 10% by weight of the composition.
The composition of the invention may additionally comprise a skin lightening agent. The skin lightening agent is preferably chosen from a vitamin B3 compound or its derivative e.g. niacin, nicotinic acid, niacinamide or other well known skin lightening agents e.g. aloe extract, ammonium lactate, azelaic acid, kojic acid, citrate esters, ellagic acid, glycolic acid, green tea extract, hydroquinone, lemon extract, linoleic acid, magnesium ascorbyl phosphate, vitamins like vitamin B6, vitamin B12, vitamin C, vitamin A, a dicarboxylic acid, resorcinol derivatives, hydroxycarboxylic acid like lactic acid and their salts e.g. sodium lactate, and mixtures thereof. Vitamin B3 compound or its derivative e.g. niacin, nicotinic acid, niacinamide are the more preferred skin lightening agent as per the invention, most preferred being niacinamide. Niacinamide, when used, is preferably present in an amount in the range of 0.1 to 10%, more preferably 0.2 to 5% by weight of the composition.
The composition according to the invention may also comprise other diluents. The diluents act as a dispersant or carrier for other materials present in the composition, so as to facilitate their distribution when the composition is applied to the skin. Diluents other than water can include liquid or solid emollients, solvents, humectants, thickeners and powders.
The composition of the invention may comprise a conventional deodourant base as the cosmetically acceptable carrier. By a deodorant is meant a product in the stick, roll-on, or propellant medium which is used for personal deodorant benefit e.g. application in the under-arm or any other area which may or may not contain anti-perspirant actives.
Deodorant compositions can generally be in the form of firm solids, soft solids, gels, creams, and liquids and are dispensed using applicators appropriate to the physical characteristics of the composition.
The compositions of the present invention can comprise a wide range of other optional components. The CTFA Cosmetic Ingredient Handbook, Second Edition, 1992, which is incorporated by reference herein in its entirety, describes a wide variety of non-limiting cosmetic and pharmaceutical ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention. Examples include: antioxidants, binders, biological additives, buffering agents, colorants, thickeners, polymers, astringents, fragrance, humectants, opacifying agents, conditioners, exfoliating agents, pH adjusters, preservatives, natural extracts, essential oils, skin sensates, skin soothing agents, and skin healing agents.
According to another aspect of the present invention there is provided use of a composition of the first aspect of the invention for obtaining SPF equal to or higher than 15 or UVAPF equal to or higher than 4. The SPF is preferably higher than 20, more preferably higher than 25. The UVAPF is preferably higher than 8. The use is preferably for non-therapeutic benefits.
The invention is now further described by way of the following non-limiting examples.
Various compositions (in cream format) as shown in table 1 were prepared using different non-ionic surfactants. The difference between the various compositions were in the type of non-ionic surfactant used which are detailed in table 2. The SPF of the various compositions (examples 1-11) were measured and the results are shown in table 2. Invitro-SPF was measured using the Optometrics 290S instrument model. The substrate used was a 7.6 cm Transpore tape procured from 3M Company. The sample was applied at 2 mg/cm2.
#The polymer is available as a 20% dispersion in water and the dispersion is added at 2% into the composition.
The sensory property in terms of skin feel on application to the skin was determined for example 1, 2, 4 and 5 and this was compared to the skin feel of example 3. The study indicated that comparable skin feel is obtained for the examples 1, 2, 4 and 5 as compared to a sample outside the invention (example 3).
The data in table 2 indicates that compositions as per the invention (examples 1, 2, 4 and 5) which meet the selective criteria of the non-ionic surfactant provide for vastly improved SPF, with no compromise on the skin feel, as compared to a composition without a non-ionic surfactant and polymer (example 3) and non-ionic surfactant not meeting the selective criteria (examples 6 to 11).
Various compositions (in cream format) as shown in table 3 were prepared using different polymers. The difference between these compositions were in the type and/or concentration of polymers which are shown in table 4. These compositions were applied on the skin by a panel of experts and the summary of the sensory perception is given in table 4.
Some of the polymers, in table 4 are commercially available as a dispersion in water but the concentration as given in table 4 is on dry weight basis.
The types of polymers used were as follows:
HASE—Hydrophobically modified alkali soluble emulsion which is an acrylate/R-methacrylate copolymer or crosspolymer.
ASE—Alkali soluble emulsion
HEUR—Hydrophobically modified Ethylene Oxide Urethane
HMHEC—Hydrophobically modified Hydroxy ethyl cellulose
@—Ammonium Acryloyldimethyltaurate/VP copolymer
@@—Ammonium Acryloyldimethyltaurate/Beheneth-25 Methacrylate crosspolymer
#—Naturally occurring polysaccharide
##—Made from naturally occurring cellulose
&&—U-15 which is a Poly Vinyl Pyrollidone Copolymer available from Induchem.
̂̂—Pemulen TR-2 is an acrylate/C10-30 alkyl acrylate crosspolymer.
The data in table 4 indicates that use of a polymer as per the invention along with the selective non-ionic surfactant (examples 1, 14-16, 21, 22 and 26) provides for the desired sensory properties while use of only the polymer alone, or only the surfactant alone or use of polymer outside the invention gives unacceptable sensory properties. (examples 12, 13, 17 to 20 and 23 to 25).
Various compositions (in lotion format) were prepared as shown in table 5. They were then tested for SPF similar to the method used for measuring SPF of example 1. The data is summarized in table 5.
The data in table 5 indicates that use of higher levels of hystric acid provides for the high desirable values of SPF.
Various compositions as shown in table 1 were prepared using different non-ionic surfactants. The difference between the various compositions were in the type of non-ionic surfactant used which are detailed in table 6. The SPF of the various compositions (examples 30-34) were measured and the results are shown in table 6. Invitro-SPF was measured using the Optometrics 290S instrument model. The substrate used was a 7.6 cm Transpore tape (3M Company). The sample was applied at 2 mg/cm2.
The data in table 6 indicates that compositions as per the invention (examples 32 to 34) which meet the selective criteria of the non-ionic surfactant provide for vastly improved SPF as compared to a composition without a non-ionic surfactant and polymer (example 3) and non-ionic surfactant not meeting the selective criteria (examples 30 and 31).
Compositions in cream format as shown in table 7 were prepared and the invitro UVAPF values were measured. The data is summarized in table 7.
The data provided in table 7 indicates that compositions as per the invention (example 36) provides for enhanced UVAPF values as compared to a composition outside the invention (example 35).
The invention thus provides for a high SPF/UVAPF sunscreen composition comprising relatively low amount of sunscreen compounds while having acceptable sensorial properties.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1610/MUM/2010 | May 2010 | IN | national |
| 2062/MUM/2010 | Jul 2010 | IN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/058176 | 5/19/2011 | WO | 00 | 3/21/2013 |
