WO2019190649A1

WO2019190649A1 - A method of cleansing skin using a two-part, hydrosilylation curable silicone composition

Info

Publication number: WO2019190649A1
Application number: PCT/US2019/017794
Authority: WO
Inventors: Alexis BOBENRIETH; Xavier Thomas; Isabelle Van Reeth
Original assignee: Dow Silicones Corporation
Priority date: 2018-03-28
Filing date: 2019-02-13
Publication date: 2019-10-03

Abstract

A method of cleansing skin comprising applying to a surface of a skin, where an unwanted material is on the surface of the skin, a hydrosilylation curable silicone composition comprising A) an organopolysiloxane comprising at least two unsaturated hydrocarbyl groups; B) an organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms; and C) a hydrosilylation catalyst; wherein A) and B) will react in the presence of component C); subjecting the hydrosilylation curable silicone composition to sufficient conditions to form a cured composition, where the cured composition comprises the product of the reaction of A) and B), and removing the cured composition from the surface of the skin, where a portion of the unwanted material is removed from the surface of the skin with the cured composition.

Description

A METHOD OF CLEANSING SKIN USING A TWO-PART, HYDROSILYLATION CURABLE

SILICONE COMPOSITION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] None

BACKGROUND OF THE INVENTION

[0002] Methods of cleansing skin have been developed for thousands of years. Some familiar methods include soap and water, detergents, oils, and antibacterial gels. Other recent methods have been developed to meet specific niches. For example, cleansing strips, such as“pore strips,” consist of an adhesive on a fabric strip. The strip is applied to skin with the adhesive toward the skin. When the strip is removed, unwanted matter sticks to the adhesive and is removed.

[0003] Two-part silicone compositions have been applied to the skin for different applications such as masks, release of actives into the skin, and wound protection.

[0004] Existing methods of cleansing skin can still be improved. For example, methods of cleaning skin can provide improved cleansing or improved aesthetic properties, eliminate the need for rinsing in water, or provide cleansing applications that can be used in non-traditional locations.

BRIEF SUMMARY OF THE INVENTION

[0005] The present invention is directed to a method of cleansing skin comprising applying to a surface of a skin, where an unwanted material is on the surface of the skin, a hydrosilylation curable silicone composition comprising A) an organopolysiloxane comprising at least two unsaturated hydrocarbyl groups; B) an organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms; and C) a hydrosilylation catalyst;

wherein A) and B) will react in the presence of component C); subjecting the hydrosilylation curable silicone composition to sufficient conditions to form a cured composition, where the cured composition comprises the product of the reaction of A) and B), and removing the cured composition from the surface of the skin, where a portion of the unwanted material is removed from the surface of the skin with the cured composition.

[0006] The present invention provides improved skin cleansing and provides cleansing where rinse water may not be available.

DETAILED DESCRIPTION OF THE INVENTION

[0007] The invention has technical and non-technical advantages. One of the problems solved by the method is provision of cleansing to healthy and unhealthy skin. The solution comprises applying the curable silicone composition described below to skin having unwanted materials on its surface, allowing the curable silicone composition to cure to form a cured composition, and then removing the cured composition from the skin with a portion of the unwanted material adhered, encapsulated, or otherwise bound to or in the cured composition. Another problem solved by the method of the invention is the cleansing of skin when water and/or surfactant is not available or not desired. The problem is solved as described above without the presence or use of water. The unwanted material is removed and no water and/or surfactant need be used in the process.

[0008] Aspects of the invention are described herein using various patent terms. For example,“alternatively” indicates a different and distinct embodiment.“Comparative example” means a non-invention experiment.“Comprises” and its variants (comprising, comprised of) are open ended.“Consists of” and its variants (consisting of) is closed ended. “Contacting” means bringing into physical contact.“May” confers a choice, not an imperative. Optionally” means is absent, alternatively is present.

[0009] Aspects of the invention are described herein using various chemical terms. The meanings of said terms correspond to their definitions promulgated by IUPAC unless otherwise defined herein. For convenience, certain chemical terms are defined.

[0010] As used herein,“surface” means the outer portion of the skin exposed to the air.

[0011] A method of cleansing skin, the method comprising:

applying to a surface of a skin, where an unwanted material is on the surface of the skin, a hydrosilylation curable silicone composition comprising

A) an organopolysiloxane comprising at least two unsaturated hydrocarbyl groups;

B) an organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms; and

C) a hydrosilylation catalyst;

wherein A) and B) will react in the presence of component C);

subjecting the hydrosilylation curable silicone composition to sufficient conditions to form a cured composition, where the cured composition comprises the product of the reaction of A) and B), and

removing the cured composition from the surface of the skin, where a portion of the unwanted material is removed from the surface of the skin with the cured composition.

[0012] A hydrosilylation curable silicone composition is applied to a surface of a skin comprising an unwanted material on the skin’s surface. The hydrosilylation curable silicone composition comprises A) an organopolysiloxane comprising at least two unsaturated hydrocarbyl groups; B) an organohydrogenpolysiloxane comprising at least two silicon- bonded hydrogen atoms; and C) a hydrosilylation catalyst.

[0013] As used herein,“skin” means human skin, healthy or unhealthy.

[0014] The hydrosilylation curable silicone composition of the invention is curable to a cellular or noncellular gel or elastomeric form in which it serves to bind, i.e. contain or entrap, the other components of the formulation and the unwanted material on the skin’s surface, and may provide a major or minor proportion of the formulation. The composition may be curable at standard temperature and pressure conditions or room temperatures, alternatively 20 °C plus or minus 10 °C, alternatively from 15 to 40 °C, and ambient pressure, alternatively typical room pressures, and thus permits the formulation to be cured on the skin. The polysiloxanes employed have silicon-bonded unsaturated organic groups, e. g. vinyl groups, available for reaction with silicon-bonded hydrogen atoms in presence of a hydrosilylation catalyst for example a platinum or rhodium compound. The addition reaction which occurs is appropriate to yield chain extended or crosslinked unfoamed resinous or elastomeric silicone products.

[0015] Suitable organopolysiloxanes having unsaturated hydrocarbyl groups A) for reaction with polysiloxanes having silicon-bonded hydrogen atoms include polydiorganosiloxanes which have sufficient unsaturated groups for formation of the polymer network, for example polysiloxanes having siloxane units according to the general formula

^Rm^R’SiO(₃_m)/2

in which each ^R independently represents a monovalent hydrocarbon group having up to 20 carbon atoms, for example a lower alkyl or phenyl group e.g. a methyl radical, m is 1 or 2 and ^R' represents a monovalent aliphatically unsaturated group, for example cyclohexenyl or a group ^R"CH=CHFT", where ^R" represents a divalent aliphatic chain linked to the silicon atom and FT" represents a hydrogen atom or an alkyl group; examples of groups FT are thus vinyl, allyl and hexenyl. These organopolysiloxanes A) also comprise units

^R _nSiO(4_-n)/2 in which ^R is as referred to above, and n is 1 , 2 or 3. Preferably, these polysiloxanes A) have from 0.01 % (w/w) and 45% (w/w), alternatively 0.01 % to 1 % by weight of aliphatically unsaturated groups, based on the weight of the organopolysiloxane comprising unsaturated groups, and a viscosity of the order of about 10 mm²/s to about 25000 mm²/s. More preferably their viscosity lies in the range 100 mm²/s to 2000 mm²/s.

[0016] In one embodiment, the organopolysiloxane comprising at least two unsaturated hydrocarbyl groups is vinyl-terminated and/or hexenyl-functionalized and/or hexenyl- terminated polydimethylsiloxane.

[0017] Suitable organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms B) include polymers having units according to the general formula

Rp^HSiO(3-p)/2 in which each R represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms, for example a lower alkyl or phenyl group e.g. a methyl group and p is 1 or 2. The organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms may also comprise units

R_nSiO(4_-n)/2 as referred to above. Preferably this organohydrogenpolysiloxane having at least two silicon- bonded hydrogen atoms has from 0.05% (w/w) and 2.5% (w/w), alternatively from 0.5% to 2.0% by weight of silicon-bonded hydrogen atoms based on the weight of the organohydrogenpolysiloxane. We prefer that each R represents a methyl group. Preferably, terminal groups of the organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms have the formula R¾iO-_|/2 where each R represents a methyl group.

Suitable organohydrogenpolysiloxane comprising at least two silicon-bonded hydrogen atoms include those comprising MeHSiO units with or without the presence of Me2SiO units and having viscosities of the order of from about 1 to about 1000 mm²/s more preferably from about 5 to about 50 mm²/s. One skilled in the art would know how to make or acquire organohydrogenpolysiloxane and organopolysiloxanes comprising unsaturated hydrocarbyl groups.

[0018] The hydrosilylation curable silicone composition cures within 15 minutes, alternatively 10 minutes, alternatively within five minutes or less of mixing, so that the user is required to keep the composition on their skin for only a short time while curing takes place. In order to achieve satisfactory cure it is important that the ratio of silicon-bonded hydrogen atoms of the organopolysiloxane having silicon bonded hydrogen atoms to all groups reactive therewith in the hydrosilylation curable silicone composition is appropriate, so that enough of the organopolysiloxane having silicon bonded hydrogen atoms is present to effect the desired cure. We have found it possible to provide formulations according to the invention which cure within three minutes or less of mixing of the formulation at room temperature and humidity (i.e. about 60% to 80% relative humidity). The curing time is dependent on various factors, including the type and proportion of other components present in the formulation and especially the salt materials, which tend to retard the cure significantly.

[0019] The hydrosilylation catalyst is not particularly limited. In one embodiment, the hydrosilylation catalyst comprises platinum. Platinum catalysts may take any of the known forms, ranging from platinum as deposited on carriers such as silica gel or powdered charcoal, to platinic chloride, salts of platinum and chloroplatinic acids. A preferred form of platinum is chloroplatinic acid either as the commonly obtainable hexahydrate or the anhydrous form, on account of its easy dispersibility in organosilicon systems and its non-effect on color of the mixture. Platinum complexes may also be used e.g. those prepared from chloroplatinic acid hexahydrate and divinyl tetramethyldisiloxane. If longer cure time is desired, one skilled in the art would know to include in the hydrosilylation curable silicone composition one of the known platinum catalyst inhibitors such as cyclic polymethylvinylsiloxane compound or an acetylenic alcohol e.g. methyl butanol but these are not generally preferred in a formulation according to the invention. The rate of cure of the hydrosilylation curable silicone composition is dependent not only upon the silicone polymer forming ingredients but also upon the nature of the other ingredients of the mixture, including and additional materials commonly used in such formulations such as filler, colorants, dyes, pharmacological agents, etc. and any salts present during the curing. The cure rate of the silicon composition may be modified by adjusting the catalyst level, reactive species ratio, and adding cure inhibitors known the art.

[0020] If desired, other adjuvants may be incorporated in the silicone composition for example fillers, colorants, colored indicators, extenders, diluents and processing aids for example cyclic or linear polydiorganosiloxanes. The presence of some silica filler or surface- treated silica filler is desirable when strongly elastomeric properties are required of the cured composition. In one embodiment, the invention comprises a filler, alternatively a silica filler, alternatively a surface treated filler.

[0021] The filler may be surface treated with a surface treating agent. The surface treating agent may include silanes, including, but not limited to, disilanes, and trisilanes; siloxanes, including, but not limited to, disiloxanes, trisiloxanes; and silazanes. The filler treating agent typically contains groups that are reactive with the filler surface, but such reactive groups are not required. The reacitve groups included, but are not limited to, hydroxy, alkoxy, halo, hydrido, siloxy, unsaturated hydrocarbyl, and nitro. The filler treating agent may contain other non-reative groups such as alkyl groups having from 1 to 8 carbon atoms. Examples of filler treating agents include, but are not limited to hexamethyldisilazane, divinyltetramethyldisiloxane, and tetramethyldisiloxane.

[0022] In one embodiment, the hydrosilylation curable silicone composition further comprises an oil absorbing powder. The oil absorbing powder is not particularly limited except that it should be compatible in the hydrosilylation curable silicone composition. For example, the oil absorbing powder should not react with A) or B). In one embodiment, the hydrosilylation curable silicone composition comprises and oil absorbing powder and the oil absorbing powder is hydrophobic powder, alternatively one or more of a silica, a silicone elastomer, a clay, a polymeric carbohydrate, a copolymer of acrylic and acrylates, a polyvinylpyrrolidone, or microbeads, alternatively clay, alternatively silca, silica silylate, silicone rubber powder, kaolin or bentonite clay, alternatively kaolin or bentonite clay.

[0023] When the oil absorbing powder is present in the hydrosilylation curable silicone composition, the hydrosilylation curable silicone composition comprises from 0.1 to 10%, alternatively form 1 to 5%, alternatively from 1 to 3% of the oil absorbing powder based on the weight of the hydrosilylation curable silicone composition.

[0024] Hydrosilylation curable silicone compositions according to the invention are typically curable at room temperature when mixed, and therefore are normally used as cleansing compositions immediately upon mixing the various components. In those cases in which it is desired to store the formulation prior to admixture, this may be achieved by storing the formulation in separate parts one of which contains the catalyst for the curable silicone composition and one of which contains the organopolysiloxane comprising at least two silicon- bonded hydrogen atoms. When other materials are present in the composition during storage, it may be preferable to include it in only one of the parts of the composition in order to preserve its effectiveness.

[0025] A hydrosilylation curable silicone composition according to the invention preferably comprises from 10 to 70% by weight of the agent (A) and (B) and from 90 to 30% by weight of the other components of the composition.

[0026] A hydrosilylation curable silicone composition according to the invention preferably comprises from 0.001 to 30%, alternatively 0.1 to 10%, alternatively 0.5 to 5% (w/w) of hydrosilylation catalyst in the composition. [0027] In one embodiment, the hydrosilylation curable silicone composition further comprises up to 30%, alternatively up to 29, alternatively from 5 to 28%, alternatively 10 to 25% (w/w) of filler.

[0028] The unwanted material on the surface of the skin is not particularly limited. In one embodiment, the unwanted material on the surface of the skin is an oil, a body fluid or a solid matter such as dirt. In one embodiment, the material on the surface of the skin is oil, alternatively dirt, alternatively body fluid. The skin may also be healthy or damaged. Healthy skin is skin that does not contain any lacerations or other ailments. Damaged skin is considered skin that is not healthy, such as skin having lacerations, or other wounds, or other conditions such as a rash or eczema.

[0029] The hydrosilylation curable silicone composition may be applied to the skin according to known methods and is not particularly limited. The hydrosilylation curable silicone composition may be applied to the skin in two parts and mixed on the skin using an implement such as a spatula or tongue depressor, alternatively the hydrosilylation curable silicone composition may be combined in a container such as a paper cup and then mixed with an implement and applied to the skin with the implement or hand. In one embodiment, the hydrosilylation curable silicon composition is packaged in dual compartment packaging, then combined by mixing the two parts in the packaging after getting them in contact, (e.g., breaking a partitioning in the packaging) and finally applied to the skin with packaging or hand., One skilled in the art would know how to apply the hydrosilylation curable silicone composition to the skin.

[0030] The hydrosilylation curable silicone composition is subjected to conditions sufficient to cure the hydrosilylation curable silicone composition, alternatively to a temperature from 15 °C to 40 °C at atmospheric pressure, alternatively ambient temperature and pressure. Typically, sufficient conditions are room temperature conditions, alternatively from 20 °C to 35 °C and atmospheric pressure, alternatively from 87 to 105 kilopascals (kPa).

[0031] The hydrosilylation curable silicone composition is subjected to conditions sufficient to cure the hydrosilylation curable composition by exposing to atmospheric conditions, using a heating appliance, such as a hair drying to blow warm air on the curable silicone composition, or applying a warming pad to the curable silicone composition. One skilled in the art would know how to expose the hydrosilylation curable silicone composition to conditions sufficient to cure the hydrosilylation curable silicone composition. [0032] When the hydrosilylation curable silicone composition is applied to the skin, oil and dirt can be absorbed into the hydrosilylation curable silicone composition and/or trapped in the hydrosilylation curable silicone composition as it cures to the cured composition.

[0033] The cured composition comprises the reaction product of A) and B). The cured composition further comprises a portion of the unwanted material from the surface of skin and any other ingredients and reaction products of the hydrosilylation curable composition. The reaction product of A) and B) is a crosslinked organopolysiloxane which is crosslinked by the reaction of the Si-H groups of B) with the unsaturated hydrocarbyl groups of A). The consistency of the cured composition is such that it is hard enough and have acceptable adhesive properties to be peeled from the skin. One skilled in the art would know how to choose compounds A) and B) such to produce a cured composition on curing to be of sufficient hardness and adhesion to be peeled from the skin.

[0034] The cured composition is removed from the skin. How the cured composition is removed from the skin is not particularly limited. The cured composition could be removed from the skin using one’s fingers or tweezers. The cured composition may be removed from the skin after a certain time. In one embodiment, the cured composition is removed from the skin in the time from immediately after the cured composition is formed to up to 24 hours, alternatively up to 5 hours after it has formed, alternatively up to one hour after it has formed, alternatively from immediately after formed to 15 minutes after formed. The cured composition is formed after the curable silicone composition has cured to a point that it is removable from the skin by peeling from the skin.

[0035] When the cured composition is removed from the unwanted material (i.e, dead skin, dirt, oil, and other unwanted matter) is removed from the skin with the cured composition leaving the skin noticeably cleaner than before the hydrosilylation curable silicone composition was applied to the skin. In one embodiment, up to 100% (w/w), alternatively 10 to 99.9 %, alternatively 50 to 99.9% of the unwanted material is removed from the skin with the cured composition.

[0036] The method of the invention may be repeated to further clean the skin.

[0037] The method of the invention is useful for cleansing of healthy or unhealthy skin to removed unwanted material and for situations where water is unavailable or undesirable. For example, the method may be used to remove water-reactive materials from the skin.

EXAMPLES [0038] The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention. All percentages are in wt. %. Table 1 . List of abbreviations used in the examples.

Examples 1 -8

[0039] Several powders were incorporated into hydrosilylation curable silicone compositions to determine if the absorption of oils could be improved. Three types of PolyOx (N10NF, 1 105NF and 301 NF), one silica (VM2270), one silicone elastomer (9701 ) and 2 clays (white

Kaolin and Bentonite Exm0242 were tested. All the powders were incorporated into the compositions at 2% (w/w) except for the VM2270 which was incorporated at 0.5% (w/w). The powders were dispersed into the composition using a dental mixer. The formulations are listed below in Table 2. Parts A and B were mixed separately at room temperature. The dispersion quality of the powders was noted visually.

Table 2. Formulations of Examples and Comparative Examples.

^*1 , 5-8 are practical examples; C2, C3 and C4 comparative examples [0040] The two part hydrosilylation curable silicone composition as described in example 1 , and 5-8 (2-4 excluded because formed poor dispersions) were evaluated for cleansing performance as follows: A mixture composed of 1 part of Carbon black and 1 part of mineral oil was applied on the forearm. On the top of this mixture, 1 part of Part A and 1 part of Part B were applied in a sufficient quantity to cover the area treated with the Carbon black and mix thoroughly on the forearm. The mixed parts were left to cure on the skin until the film is dry (around 15 minutes). The film is then stripped from the forearm removing all the carbon black/oil mixture. None of the powders impacted the cure kinetics.

[0041] Next, Example 1 was tested on the flesh of apples (representing damaged skin with exudates) which had been sliced in half and the carbon black and mineral oil mixture applied to the apples. The composition was applied, allowed to cure at room temperature, and then peeled from the surface using fingers. The apple was visually cleaner than after original application of the carbon black and mineral oil demonstrating that the presence of some liquid on the substrate to be cleaned did not impact the curing or cleansing efficiency.

[0042] Sebum absorption test:

Examples 6 and 8 were evaluated for sebum absorption by placing sebum in a petri dish and then applying the composition of Examples 6 and 8 to the petri dishes over the sebum and allowing the formulation to cure for several minutes. Example 6 removed 78% (w/w) of the sebum after peeling the cured composition from the dish. Example 8 did not cure in the presence of sebum.

EXAMPLE 9

[0043] Oil in Water Peel Off Mask Formulation

[0044] Part A and Part B were prepared separately. The ingredients of Phase A and Phase B were mixed at room temperature until homogeneous. Phase B of Part B was adjusted to pH 5.5 with citric acid and sodium hydroxide. Phase B was slowly added to phase A using high speed mixing until homogeneous.

[0045] One part of Part A and one part of Part B were mixed together and then applied immediately in a sufficient quantity to cover the nose area (part of the face where the level of sebum is high). The mixture was then left for curing until the film was dry (around 15 minutes). The film was then stripped from the nose area which was significantly less shiny indicating sebum removal.

Claims

That which is claimed is:

1 . A method of cleansing skin, the method comprising:

C) a hydrosilylation catalyst;

wherein A) and B) will react in the presence of component C);

2. A method according to claim 1 , wherein the organopolysiloxane comprising at least two unsaturated hydrocarbyl groups is vinyl-terminated and/or hexenyl-functionalized polydimethylsiloxane.

3. A method according to any one of the preceding claims, wherein the organohydrogenpolysiloxane comprises units according to the formula

^Rp^HSi0(3-p)/2 in which each R represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms.

4. A method according to any one of the preceding claims, wherein the hydrosilylation catalyst comprises platinum and the hydrosilylation curable silicone composition will cure at standard temperature and pressure conditions.

5. A method according to any one of the preceding claims, wherein the material is an oil, a body fluid or a solid matter.

6. A method according to any one of the preceding claims, wherein A) has a vinyl content and the vinyl content of A) is between 0.01 % (w/w) and 45% (w/w) and B) has a silicone- bonded hydrogen content and the silicone bonded hydrogen content of B) is between 0.05% (w/w) and 2% (w/w).

7. A method according to any one of the preceding claims, wherein the hydrosilylation curable silicone composition further comprises a filler.

8. A method according to claim 7, wherein the filler is a surface treated silica.

9. A method according to any one of the preceding claims, wherein the hydrosilylation curable silicone composition further comprises an oil absorbing powder.

10. A method according to claim 9, wherein the oil absorbing powder is hydrophobic.

1 1 . A method according to claim 10, wherein the oil absorbing powder is selected from one or more of a silica, a silicone elastomer, a clay, a polymeric carbohydrate, a copolymer of acrylic and acrylates, a polyvinylpyrrolidone, and microbeads.

10. A method according to claim 1 1 , wherein the oil absorbing powder is clay and wherein the clay is kaolin or bentonite.

1 1 . A method according to any one of the preceding claims, wherein the skin is healthy.