DESCRIPTION

Technical field of the invention

The invention concerns a composition with a relative dose that comprises a volatile carrier and a sun filter for use in the protection of skin from UV rays. The sun filter is present in a certain concentration that ensures, if applied in a certain quantity on the skin, a certain protection factor.

State of the art

Exposure to the sun without sun protection results in redness, swelling and blisters depending on how serious the burning is. The market offers a vast range of sun protection products with different sun protection factors (SPF) that is defined as the ability of a sun filter to defend the skin from actinic attack. The meaning of such a factor is identified as a sun exposure time, multiple of the erythema time. A factor 50 will lead to sun erythema after an exposure time 50 times longer than that expected without protection. In order to protect customers, according to current regulations, some protection classes are provided for: low SPF (SPF 6 and 10), medium SPF (SPF 15 and 20), high SPF (SPF 30 and 50) and very high SPF (SPF 50+). Protective products with SPF < 6 are not considered to be sun filters.

By convention, the indication of the SPF on sun cream containers corresponds to the SPF reached if an amount of 2 mg/cm ² of the product is applied on the skin. For the customer it is difficult to dispense the correct amount per cm ² of skin, who often does not have devices permitting a set and reproducible quantity of sun product to be dispensed. In order to apply 2 mg/cm ² of a typical sun cream available on the market onto the skin of an adult, roughly 35 g of product are necessary since the body surface of an average adult is about 17,500 cm ² .

The SPF (Sun Protection Factor) is the sun protection factor of a cosmetic product calculated as the ratio between the minimum dose of solar energy able to cause a visible erythema on the skin protected by the product and the minimum dose of solar energy able to cause a visible erythema on the skin not protected by the product. An erythema is a reddening of the skin caused by ultraviolet (UV) radiation. UVR is ultraviolet radiation comprised between 290 nm and 400 nm, UVB is electromagnetic radiation between 290 nm and 320 nm, and UVA is electromagnetic radiation comprised between 320 nm and 400 nm.

It is known that sun filters block electromagnetic radiation by reflection or absorption of UV rays. Sun protection SPF is influenced by the type and quantity of filters present in the formula. In order to go from an SPF 10 to an SPF 20 the quantity of filters present in the formula must be doubled with a gain of only 5% blocking of UVB rays. Such a situation is much worse with the increase of the SPF value. Indeed, obtaining an SPF 60 requires roughly triple the amount of filters with respect to SPF 20, obtaining the blocking of only 3.3% more radiation. A product marked with SPF 10 blocks 90.0% of UVB, with SPF 20 95.0%, with SPF 30 96.7% and with SPF 60 98.3%.

In order to have the correct sun protection, the customer must use a different product for each type of skin or degree of tan obtained, each time selecting the suitable SPF.

The state of the art, for example Schalka et al. in "The influence of the amount of sunscreen applied and its sun protection factor (SPF): evaluation of two sunscreens including the same ingredients at different concentrations" (Photodermatology, Photoimmunology & Photomedicine 25, 175 - 180), warns that some customers tend to apply less than the recommended amount of sun cream (2 mg/cm ² ), which results in too low protection.

Presentation of the invention

The aim of the invention is to propose a composition to protect skin against UV rays and a dosing thereof to overcome the aforementioned drawbacks, and in particular to not have to use a different protective product for every skin type and/or degree of tan.

The aforementioned purposes, other purposes and advantages that will be highlighted hereinafter are accomplished by a composition according to the first claim and in particular by a composition for use in the protection of skin from UV rays

(a) which comprises at least one volatile carrier and at least one sun filter wherein said sun filter is present in a certain base concentration that ensures, if the composition is applied in a certain base quantity on the skin, a certain base sun protection factor, and

(b) said certain base quantity of the composition is to be applied, with a dispensing device adapted for dispensing defined and reproducible quantities of said composition, n times onto the skin to deposit a total amount of the composition corresponding to n times said certain base quantity on every cm ² of skin thus treated, thereby adjusting the relative sun protection factor wherein the applications that follow the first application take place after the evaporation of the volatile carrier of the previous application and wherein said evaporation takes place in a time period not exceeding 10 minutes, preferably in a period not exceeding 5 minutes, more preferably in a period < 4 minutes and wherein the n times of the applications preferably take place in portions of a whole or half dose of the certain base quantity and wherein n is a number > 1 , preferably a natural number, more preferably 2 or 3.

A whole dose thus corresponds to the certain base quantity and a half dose corresponds to half the certain base quantity.

The composition and the relative dosing according to the invention have the advantage of not having to prepare formulations containing very high concentrations of filters and of having a single adjustable product in terms of SPF that can be reached. It is not necessary to change the product to apply a higher protection in the first days of exposure to then lower the SPF in the following days, as it will not be necessary to choose a product suitable for every member of the family, i.e. for every skin type present in the family. Moreover, it is possible with the same product to obtain different sun protection in different areas of the body that need different protection, for example: the face and the neckline notoriously need high or very high protection (SPF 50 or 50+), whereas tanned legs require medium protection (SPF 20).

The composition and the relative dosing according to the invention allow adjustment of the SPF. For example, purchasing a product with SPF 20 applied 2 or 3 times (thus n = 2 or 3) over the first days will ensure protection factors 40 or 60 and the same product applied in a smaller quantity (for example 1 mg/cm ² ) or with less applications (thus n = 0.5) will be optimal for protection over the next days, in which the desired sun protection will be less than 20. In the case of people with phototype 1 or 2 who find it difficult to get a tan, they will have the possibility of personalising their SPF by still keeping high values.

The sun filters can be UVA and/or UVB filters. The standard in the case of protection also against UVA rays establishes that the UVA protection is not less than one third of UVB protection. Advantageously, the composition according to the invention is a formulation in spray form, i.e. suitable for being nebulized in the form of an aerosol.

With a base protection factor of 20, with two or three repetitions an SPF of 40 or 50+ is reached, respectively. The value of n can also be, for example, 1 .5 to obtain an SPF value of 30. In this case, half of the amount of 2 mg/cm ² can be applied 3 times or one whole dose of the above amount can be applied 1 time and the second time half dose of the above amount can be applied, or vice versa. This example illustrates the preference expressed in the first claim that the n times of the applications take place preferably in portions of a whole or half dose of the certain base quantity.

Advantageously, said base protection factor is comprised between 6 and 25, preferably between 10 and 20, more preferably it is about 20. With factors of this type it is easy to make higher SPFs. The choice of the base SPF value determines the possible increments in the change of SPF. Low values allow finer adjustments of the final SPF reached on the skin.

Preferably, the certain base quantity corresponds to about 2 mg/cm ² of skin. This value refers to the existing standards for the indication of the SPF on the sun product on sale.

In a preferred variant of the invention, the volatile carrier is selected among ethyl alcohol and volatile silicones and mixtures thereof, but the invention is not limited to these examples. The volatile carriers preferably are adapted for dissolving the ingredients of the composition, in particular the sun filters, and evaporate easily. Advantageously, they are not toxic and they are not harmful to the environment.

In a preferred variant of the invention, the sun filter is selected among wide spectrum UVA I filters, in particular 2,2'-(6-(4-methoxyphenyl)-1 ,3,5-triazine- 2,4-diyl)bis(5-((2-ethylhexyl)ossi)phenol), butyl methoxydibenzoylmethane, diethylamino hydroxybenzoyl hexyl benzoate, 2-2'-bis-(1 ,4-phenylene)1 H- benzimidazole-4,6-disulphonic acid salt, 2,2'-methylene-bis-6(2H-benzotriazol- 2-il)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol; UVB/UVA II filters, in particular 3-(4- methylbenzylidene)-camphor, benzophenone-3, benzophenone-4, diethylhexyl butamido triazone, ethylhexyl methoxycinnamate, 2-ethylhexyl salicylate, ethylhexyl triazone, 4-(dimethylamino)benzoate di 2-ethylhexyl/Padimate-O, homomenthyl salicylate, octocrylene, phenylbenzimidazole sulfonic acid, polysilicone-15, titanium dioxide, tris-biphenyl triazine; and mixtures thereof. In particular, in combination with the aforementioned carriers these filters ensure a definite homogeneous distribution of the filters on the skin and quick evaporation of the carriers.

2,2'-(6-(4-Methoxyphenyl)-1 ,3,5-triazine-2,4-diyl)bis(5-((2- ethylhexyl)oxy)phenol) is also known as Bemotrizinol (USAN - United States Adopted Names, i.e. names adopted by the American Medical Association) or BEMT. Products able to be used are for example Tinosorb S or Tinosorb S Acqua, active (BASF). Butyl methoxydibenzoylmethane is also known as Avobenzone (USAN) or BMBM. Diethylamino hydroxybenzoyl hexyl benzoate is also known as DHHB. The 2-2'-bis-(1 ,4-phenylene)1 H-benzimidazole-4,6- disulphonic acid salt is also known as Bisdisulizole Disodium (USAN) or DPDT. 2,2'-methylene-bis-6(2H-benzotriazol-2-yl)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol (nano) is also known as Bisoctrizole (USAN) or MBBT (one product would for example be Tinosorb M active (BASF)). 3-(4-Methylbenzylidene)-camphor is also known as Enzacamene (USAN) or MBC. Benzophenone-3 (e.g. Uvinul M40, BASF) is also known as Oxybenzone (USAN) or BP3, whereas the USAN name of benzophenone-4 (also BP4) is Sulisobenzone. Diethylhexyl butamido triazone is abbreviated with DBT. Ethylhexyl methoxycinnamate (EHMC) is also known with its USAN name Octinoxate; an example is the product Uvinul MC80 (BASF).

2-Ethylhexyl salicylate (EHS) carries the USAN name Octisalate. Ethylhexyl triazone (EHT), like for example Uvinul T150 (BASF), has the USAN name Octyltriazone. 4-(Dimethylamino)benzoate of 2-ethylhexyl (EHDP) is known as Padimate O (USAN). Homomenthyl salicylate (HMS) has the USAN name Homosalate. The USAN name of isoamyl p-methoxycinnamate (IMC) is Amiloxate, that of octocrylene (OCR) is Octocrylene, like for example the product Uvinul N539T (BASF). Phenylbenzimidazole sulfonic acid (PBSA) is known as Ensulizole (USAN). Polysilicone-15 is abbreviated to PS15 and titanium dioxide (USAN: Titanium Dioxide) to TiO2. Nano-products able to be used exist in oily as well as aqueous phase. Tris-biphenyl triazine (nano) has the abbreviation TBPT and can be used for example in the form of the product Tinosorb A2B, active (BASF).

The composition is not limited to the sun filters listed. Other possible filters able to be used are to be found for example in attachment VI of regulation (CE) no. 1223/2009 of the European Parliament and of the Council, of 30 November 2009, on cosmetic products.

A particularly preferred composition for adjusting SPF comprises a mixture of butyl methoxydibenzoylmethane, diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl methoxycinnamate and octocrylene.

According to the invention, the evaporation of the volatile carrier between one application and the next takes place in a time period not exceeding 10 minutes, preferably in a period not exceeding 5 minutes, more preferably in a period < 4 minutes. Preferably, these times refer to amounts of composition applied in amounts of about 2 mg/cm ² of skin. The evaporation time of the volatile carrier also allows penetration of the sun filters in the skin.

The composition can also comprise one or more of the following ingredients: emollients, melanin production stimulators, nutrients and/or hydrators for the skin, agents that control the natural hydration factor of the skin, and scents. A dispensing device adapted for dispensing defined and reproducible amounts of product allows incremental dosing of the product and adjustment of the SPF according to the customer's needs. Advantageously, it involves an aerosol dispensing system. The application of aerosol allows a homogeneous distribution of the product and a quantification of the amount dispensed in terms of spray times since the amount dispensed expressed in ml dispensed per second is constant over time. A particularly preferred system that combines a homogeneous distribution of the product and the production of an aerosol that supports the easy evaporation of the volatile carrier with a continuous and constant flow of the product dispensed is preferably a system using "bag-on-valve" (BOV) technology. The BOV system, which will be explained in greater detail hereinafter, allows the product to be dispensed in pure form, i.e. without being mixed with propellants, and thus at an adjustable amount, for example, of about 1 ml per second. As a result, in this example correct application over the entire body of an adult should take about thirty seconds, taking care to spray it evenly, to obtain the distribution of 2 mg of product on every cm ² .

Preferably, in order to obtain an even and homogeneous layer of sun protection the composition according to the invention is nebulized at a distance from the skin preferably of no less than 5 cm and no more than 60 cm; this, advantageously, for a dispensing time of no less than 2-3 seconds and no more than 35 seconds (depending on the skin areas to be treated). A particularly suitable composition of aerosol application technology for sun protection and quick evaporation of the carrier of the sun filters comprises caprylic/capric triglyceride; ethylhexyl methoxycinnamate; octocrylene; diethylamino-hydroxybenzoyl-hexylbenzoate; butyl methoxydibenzoylmethane; cyclopentasiloxane; melanin formation stimulants, preferably oleoyl tyrosine, dihydroxy methylchromonyl palmitate and sponge gourd seed oil; a controlling agent of the natural hydration factor, preferably oleic acid; ethyl alcohol; C-12-C-15 alkyl benzoate; and optionally tocopheryl acetate vitamin, nutrient and hydrating oils, and scents.

These formulations in combination with dispensers adapted for dispensing defined and reproducible quantities of product have made it possible to obtain incremental protection factors from a single product applied in multiple quantities of the base amount, for example, of 2 mg/cm ² .

The SPF value increases in direct proportion to the amount of sun filter applied to the skin. A multiple of the base amount of the sun filter results in a corresponding multiple of the corresponding SPF _baS e- For example: double the amount of sun filter applied doubles the SPF reached on the skin.

As already stated, in a preferred variant of the invention, the composition is applied with a system adapted for dispensing defined and reproducible amounts of product, in particular with an aerosol system, preferably with a system using "bag-on-valve" technology. The "bag-on-valve" (BOV) system consists of an aerosol valve on which a bag is welded.

The bag contains the product to be dispensed and is located in a cylinder comprising, outside of the bag, for example, compressed air that acts as propellant on the product present inside.

In particular, a BOV type dispenser is capable of defining exactly the amount of product dispensed during application and thus allows the SPF to be adjusted as desired as a function of one's own type of skin or the degree of tanning already reached.

Advantageously, basing the application on aerosol systems, both with liquid propellant (e.g. propane/butane or dimethyl ether), and with gas propellant (e.g. compressed air or nitrogen), the amount of product dispensed per unit time of application can be established and determined and therefore it is possible to indicate a defined dose in terms of amount necessary as a function of one's own body. Such an optimal definition allows, for example, the application of the determined recommended amount of product to be used (2 mg/cm ² ).

Another aspect of the invention concerns a method for protecting skin against UV rays that uses the composition according to the invention.

A method for protecting skin from UV sun rays comprises the following steps:

(a) preparation of a composition comprising at least one volatile carrier and at least one sun filter in a base concentration;

(b) application of a determined amount of said composition on a determined area of the skin

(c) n repetitions of step (b) and

between steps (b) and (c) a waiting time for the evaporation of the volatile carrier and/or the penetration of the sun filter in the skin.

All of the characteristics indicated above for the composition(s) according to the invention are, mutatis mutandis, transferable to the method.

Variants of the invention are the object of the dependent claims. The description of preferred embodiments of the composition and of its dosing and the application method is given as a non-limiting example.

Brief description of the drawing

Figure 1 shows a partial section view of a spray cylinder of "bag-on-valve" technology as known in the state of the art and as particularly suitable for applying the composition according to the invention on the skin for protection from the sun.

Description of preferred embodiments

The in vivo study described hereinafter describes the evaluation of the increase in SPF following repeated applications on the skin. The screening was carried out on 5 volunteers. The sample used was the dry oil product SPF 20 All in One of the firm CLAIRE S.p.A that has an SPF = 21 .0 calculated in vivo according to the International Sun Protection Factor (SPF) Test Method (COLIPA document number 001 -2003; February 2003, revised in May 2006), except for the number of volunteers that is equal to 5 instead of a minimum of 10. The SPF of the product under examination was evaluated based on the recommendation of the European Commission of 22 September 2006 no. 2006/647/EC and it is therefore a product belonging to the medium protection category with a nominal SPF value on the label of 20. The sun protection factor (SPF) was also evaluated according to the International Sun Protection Factor Test Method of May 2006.

The volunteers, male or female, were aged between 18 and 70 years old and were in good general health. The subjects included in the test had skin phototype I, II and III according to the Fitzpatrick classification (Fitzpatrick, T.B., "The validity and practicability of sun-reactive skin types I through VI", Arch. Dermatol. 124, pp. 869-871 , 1988) and were not tanned on the area to be tested. The back free from skin problems and other simultaneous treatments. The COLIPA P2 standard was used as reference standard.

The back of healthy subjects was irradiated with UVA/UVB radiation produced by a certified UVA/UVB solar simulator (Xenon arc Solar Simulator). The Minimal Erythema Dose (MED) was calculated 20 ± 4 hours after irradiation. The MED is the lowest dose of ultraviolet radiation (UVR) capable of producing a first perceptible skin erythema, characterised by clearly defined edges, evident after 16 h - 24 h from exposure to radiation. The term MEDu defines the minimal erythema dose on unprotected skin, and MEDp defined the minimal erythema dose on protected skin. The individual protection factor SPF, is calculated as follows: MED _p /MED _u .

A part of the back was divided into four areas of equal size. The first area was not treated with the sun oil but with the standard P2, the second area was treated with a single application of the sun oil (2,00 ± 0,05 mg/cm ² ), the third area was treated with two applications of the sun oil (4,00 ± 0,05 mg/cm ² ) and the fourth area was treated with three applications of the sun oil (6,00 ± 0,05 mg/cm ² ). The applications were carried out evenly by spreading the oil for 20-50 seconds. The time passed between one application and the next was about 10 minutes. The exposure to the progressive doses of UV started about 15-30 minutes after the last application of the product. The SPF determined for the different areas was 0 for the first area, 21 .0 for the second, 43.7 for the third and 67.6 for the fourth. The SPF should be taken as the average SPF calculated over 5 volunteers.

On the first day the even distribution of a precise amount of product and of standard was carried out on the area to be tested, and then the area protected by the product, the area protected by the standard and the unprotected area were irradiated. The next day the MEDu and MEDp values of the product and of the standard were determined. The 95% confidence interval < 17% was reached, where CI [%] = 100 ^* c/SPF with c = t ^* s/Vn (n = number of subjects treated; s = standard deviation of the average SPF, t = value extrapolated from the Student bilateral distribution table at a probability level p = 0.05 and with (n-1 ) degrees of freedom).

An example composition for use in sun protection comprises the following ingredients and is prepared as indicated below:

Type of ingredient Amount Specific example

[w/w %]

The caprylic/capric triglyceride is placed in a mixer and then the other ingredients are added to the mass, one at a time, under stirring. When the

Uvinul A plus is added, it is left under stirring until complete solubilisation before making other additions.

Emollient: caprylic/capric 30.00 Eudermoil MCT (Dub MCT, triglyceride Waglinol 3/9280, Myritol

318) of HUWELL

CHEMICALS SPA

Sun filter: 8.20 Uvinul MC 80 of BASF ethylhexyl SPA

methoxycinnamate

with BHT

(butylhydroxytoluene)

Sun filter: octocrylene 5.50 Eusolex OCR (Acesorb

539) of MERCK S.p.A.

Sun filter: diethylamino- 2.00 Uvinul A plus Granular of hydroxybenzoyl- BASF ITALIA SPA

hexylbenzoate

Sun filter: 2.50 Eusolex 9020 of MERCK butyl S.p.A.

methoxydibenzoylmethane

Emollient: 32.00 BRB CM 50 of BRB cyclopentasiloxane International BV

Melanin formation stimulant: 0.02 Tyr-Excel of CRODA oleoyl tyrosine and sponge ITALIANA SPA

gourd seed oil; control of

the natural hydration factor:

oleic acid

Tocopheryl acetate vitamin 0.10 Vitamin E-Acetate care (DL- alpha-Tocopheryl Acetate) of BASF ITALIA SPA

In a separate container the ethyl alcohol is weighed and it is added to the mass under stirring

Volatile carrier: ethyl alcohol 17.02 Denatured Ethyl alcohol type

D of SILCOMPA

SPA

In a separate container the oils and the active ingredient are weighed and it is heated gently under stirring to facilitate the dispersion of the active ingredient. Once dispersed, the whole thing is added to the mass under stirring.

Emollient: C12-C15 alkyl 2.00 Lincol BAS of

benzoate EIGENMANN &

VERONELLI SPA

Melanin formation stimulant: 0.01 RonaCare Bronzyl of dihydroxy MERCK S.p.A.

methylchromonyl palmitate

Skin nutrient/hydrator: 0.10 Avocado Oil of

avocado oil A.C.E.F. SPA

Hydrator: Simmondsia 0.05 Golden jojoba oil of

chinensis oil ESPERIS SPA

At the end the scent is added to the mass under stirring.

Scent: hexyl cinnamal, 0,50 Profumo Experiential 2 butylphenyl sweet vanilla of

methylpropional, limonene, Givaudan Suisse SA coumarin,

alpha-isomethyl ionone,

linalool,

benzyl alcohol, citral,

benzyl benzoate, geraniol

Total 100.00

Figure 1 shows a partial section view of a spray cylinder of "bag-on-valve" technology for dispensing an aerosol as known in the state of the art, and for example from document US 2012/0071581 A1 , and as particularly suitable for applying the composition according to the invention on the skin for protection from the sun. The cylinder is wholly marked with 2. The cylinder 2 comprises a rigid can 18, which is often made from aluminium, and a flexible bag 10 that contains the product 12 that must be dispensed. A volume 20 is provided between the bag 10 and the can 18, which contains a compressed gas 16, like air, nitrogen or other compatible gases. The bag 10 is selected from materials that are compatible with the product to be dispensed 12. A valve 8 is provided for allowing communication with the inside of the bag 10.

In the production of the cylinder 2, the bag 10 is arranged inside the can 18 and the valve 8 is fixed onto the bag 10. The cover of the valve 8 is lifted from the can and the compressed gas is injected into the volume 20 until the desired pressure of the gas 16 is reached. Thereafter, the valve 8 is reinserted into the can 18 and fixed onto the neck of the can 18. The product 12 is then injected into the bag 10 through the valve 8. Once filling is complete, an actuator 6 of the valve 8 is arranged on the valve 8 itself and then a cover 4 can be placed on the actuator 6. A label 14, which shows the usage instructions and therefore the correct dosage instructions, can be applied onto the can 18. To dispense the product 12, the actuator 6 is pressed inside the valve 8 creating a channel through the valve 8 and the actuator 6 to allow the product 12 to come out.