Soap bar composition for enhancing delivery of water-soluble beneficial agents

Abstract

The present invention relates to soap bar compositions that enhance the delivery of water-soluble skin benefit agents so that the desired activity of the benefit agent is observed for an extended period of time after washing. This is achieved by absorbing / coating the benefit agent onto a specific clay, followed by a further coating with a hydrophobic material selected from wax or petrolatum.

Description

Technical Field

[0001] The present invention relates to a soap bar composition that enhances the delivery of water-soluble skin-beneficial agents. More particularly, the present invention relates to a soap bar that is used for cleaning the topical surface of the body and that can sufficiently deliver a water-soluble active substance, particularly a cationic active substance, onto the skin such that the desired activity of the beneficial agent is observed for a long time after washing.

Background Art

[0002] Products used for cleaning the topical surface of the human body are delivered through cleansing compositions. They can be used for washing hair, face, body or hands. Most of these compositions contain anionic surfactants that can be made from natural sources like soap or can be of synthetic origin. Such compositions are also used to provide effects other than cleansing, such as moisturizing, skin whitening, anti-aging, anti-inflammatory, conditioning or anti-microbial effects. Many antimicrobial active substances such as trichlorocarbanilide, triclosan, chloroxylenol, benzalkonium chloride, etc. are also included in such cleansing compositions. Active substances having a cationic charge are considered to be very effective as antimicrobial active substances. Due to the charge neutralization of such active substances in an anionic surfactant system, it has been a challenge to include a cationic active substance in such products. Since water-soluble active substances generally tend to be washed away by the rinse water, it is also a challenge to ensure the deposition of a sufficient amount of water-soluble active substance through such compositions. Compounds such as polymeric cationic active substances having a high charge density are even more difficult to incorporate into such systems.

[0003] Soap bars that are claimed to deliver active substances to the skin have been previously disclosed. US Patent Application Publication No. 2005003975 (P&G) discloses fragrance compositions having defined influential compatibility, and provides personal cleansing compositions, particularly soap bars, containing those fragrance compositions. In a preferred embodiment, the fragrance composition is encapsulated in starch or the like so as to release the fragrance when exposed to water, such as during a shower.

[0004] US Patent Application Publication No. 2005123574 (Unilever) discloses a massage toilet bar composition containing disintegrating aggregates that provide simultaneous exfoliation and massage to the skin and hair. The aggregates are produced by treating them with a hydrophilic liquid, a hydrophobic liquid, or a combination thereof. This treatment makes the aggregates softer, but not so soft as to disintegrate during bar manufacture.

[0005] The published technologies cited above disclose aggregates that claim to deliver active substances to the skin, but it has been found that they cannot deliver water-soluble active substances, particularly cationic compounds, by a soap bar such that the desired effect is reliably exerted over a long time after the cleansing action is completed.

[0006] Accordingly, there is a need in the art to provide enhanced delivery of water-soluble or cationic active substances in cleansing compositions containing a large amount of anionic surfactant. The inventors have achieved this by including the active substance within porous clay particles or coating the active substance on the porous clay particles and further coating a hydrophobic component such as petrolatum or wax thereon. The inventors have also surprisingly found that the present invention is effective when the coated clay particles are incorporated into a solid cleansing composition such as a soap bar and the delivery is not as good as when formulated into a liquid composition.

[0007] The advantage of the present invention is that such a water-soluble beneficial agent is kept separated from other soap bar components that can interact during manufacture and storage, but becomes available in a sufficiently high amount when the soap bar is used by a person during personal washing, and is thereby deposited effectively and surely at that time.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] Accordingly, an object of the present invention is to provide a composition containing an anionic surfactant for enhancing the delivery of a water-soluble skin beneficial agent.

[0010] Another object of the present invention is to provide enhanced delivery of a cationic antimicrobial active substance by such a wash-off soap bar composition.

Means for Solving the Problems

[0011] According to a first aspect of the present invention, there is provided a soap bar composition for enhancing the delivery of a water-soluble beneficial agent, comprising: (a) 40 to 80% soap; (b) Porous clay particles coated with a water-soluble beneficial agent having a water retention capacity in the range of 10 to 50% by weight and a solubility in water at 25°C of at least 0.001% by weight, and further coated thereon with a hydrophobic material selected from wax or petrolatum.

[0012] The second aspect of the present invention relates to a method for producing coated clay particles for use in the soap bar composition of the first aspect, comprising the following steps: (a) mixing porous clay particles with an aqueous solution of a water-soluble beneficial agent; (b) drying the porous particles to substantially remove moisture; (c) mixing the dried porous particles with a solution mixture of an organic solvent and a hydrophobic material; (d) separating the particulate matter from the solution mixture and drying the particulate matter to prepare the coated particles.

[0013] The third aspect of the present invention relates to a method for delivering a water-soluble active substance onto the skin, comprising the step of rinsing the skin with water after washing the skin with a solution of the soap composition of the first aspect so that the soap is substantially removed.

Mode for Carrying Out the Invention

[0014] These and other aspects, features, and advantages will become apparent to those skilled in the art upon reading the following detailed description and the appended claims. To avoid doubt, any feature of one aspect of the invention may be utilized in any other aspect of the invention. The term "comprising" is intended to mean "including" but does not necessarily mean "consisting of" or "composed of". In other words, the recited steps or options need not be exhaustive. It should be noted that the examples presented in the following description are intended to clarify the invention and are not intended to limit the invention to those examples themselves. Similarly, all percentages are weight / weight % unless otherwise indicated. Unless otherwise specified in the operating and comparative examples, or where otherwise indicated, all numbers in this specification and the claims, which indicate amounts of materials or reaction conditions, physical properties of materials and / or uses, are to be understood as modified by the term "about". A numerical range expressed in the form "x to y" is to be understood as including x and y. It is understood that where multiple preferred ranges for a particular feature are recited in the form "x to y", all ranges combining different endpoints are also contemplated. In other words, in any specification of a numerical range, any particular upper limit can be associated with any particular lower limit.

[0015] Notwithstanding the fact that the claims may be found to be multiple dependent or non-overlapping, the disclosure of the invention found herein is multiple dependent upon each other and should be considered to encompass all embodiments as found in the claims.

[0016] Where features are disclosed with respect to a particular aspect of the invention (e.g., a composition of the invention), such disclosure should be considered to apply, with the necessary modifications, to any other aspect of the invention (e.g., a method or process relating to the invention).

[0017] A soap bar composition is in the form of a formed solid and is used to clean the local surface of the body, meaning a composition mainly containing soap (salt of fatty acid). Such a composition is diluted into a solution / dispersion by water and is generally applied to the desired local surface of the body over a period from several seconds to a maximum of several minutes. Then, the composition is generally rinsed off with water so that the surface is substantially free of soap. Such a composition includes any product applied to the human body to improve appearance, cleansing, odor control or general aesthetics. The soap bar composition of the present invention may be used to clean hair (such as shampoo or conditioner), or may be used for hand wash, facial wash or body wash. The soap bar composition of the present invention is more preferably used to disinfect hands or other parts of the human body, or to deliver / deposit other skin-beneficial agents thereon.

[0018] The present invention relates to a soap bar composition formulated to ensure enhanced delivery of a water-soluble skin-beneficial agent. The soap bar composition includes 40 to 80% soap and coated porous clay particles. The porous clay particles are selected to have a water retention capacity in the range of 10 to 50% by weight. This means that for every 100 g of clay particles, 10 to 50 g of water can be absorbed or retained without appearing overly wet, i.e., the water is mainly absorbed into the pores of the clay. In other words, it still appears to be free-flowing after absorbing water. The clay particles are coated with a water-soluble beneficial agent having a solubility of at least 0.001% by weight in water at 25°C. The water-soluble beneficial agent is not necessarily only coated on the outer surface of the clay particles. "Coated therewith" means that the water-soluble beneficial agent can be partially absorbed into the pores of the clay particles, and the remainder is coated to form at least a partial layer on the outer surface of the clay particles. The clay particles thus coated with the water-soluble beneficial agent are further coated thereon with a hydrophobic material selected from wax or petrolatum.

[0019] The soap is preferably a C8 - C24 soap, more preferably a C10 - C20 soap, and most preferably a C12 - C18 soap. The cation of the soap can be an alkali metal, an alkaline earth metal, or ammonium. Preferably, the cation of the soap is selected from sodium, potassium, or ammonium. More preferably, the cation of the soap is sodium or potassium, and most preferably sodium.

[0020] A typical fatty acid blend consists of 5 - 30% by weight of coconut fatty acid and 70 - 95% of tallow fatty acid of the soap. For example, fatty acids derived from other suitable oils / fats such as peanut, soybean, tallow, palm, palm kernel, etc. can also be used in other desired proportions.

[0021] The soap is present in an amount of 40 - 80%, preferably 50 - 75% by weight of the soap bar composition.

[0022] Any water - soluble skin - beneficial agent that meets the water solubility criterion of 0.001% by weight at 25°C can be used, but one or more of an antimicrobial cationic active substance; a water - soluble vitamin or its derivative; a water - soluble sunscreen; an α - hydroxy acid or a β - hydroxy acid; or a water - soluble alkali metal salt or a water - soluble alkaline earth metal salt are preferred. Among the above active substances, more preferred are one or more of an antimicrobial cationic active substance; a water - soluble vitamin or its derivative; or a water - soluble sunscreen. The most preferred active substance is an antimicrobial polymeric cationic active substance.

[0023] The antimicrobial polymer cationic active substances that can preferably be included in the emulsion composition are one or more of polydiallyldimethylammonium chloride (PDADMAC) or chitosan, preferably PDADMAC. PDADMAC is a homopolymer of diallyldimethylammonium chloride (DADMAC). The preferred PDADMAC molecular weight for use in the present invention ranges from 200,000 to 2,000,000, preferably from 400,000 to 600,000. It is a cationic polymer that preferably has a high charge density exceeding 2 meq / gm and has a viscosity in the range of 10,000 to 20,000 mPas. The polymer is available from Lubrizol Inc. under the trade name Merquat-100 (INCI: Polyquaternium-6). The water-soluble vitamins or their derivatives that can be included are selected from one or more of vitamin C, E, B3, B5, or N-methylnicotinamide, more preferably vitamin B3. The water-soluble sunscreen agents that can be included are selected from one or more of 2-phenylbenzimidazole-5-sulfonic acid (sold as Enulizole) or ethylhexyl salicylate (sold as Neoheliopan OS). The α-hydroxy acids that can be included are selected from one or more of lactic acid, glycolic acid, or salicylic acid, preferably lactic acid. The water-soluble beneficial agent is preferably included in the range of 1 to 20% by weight of the clay particles.

[0024] The water-soluble skin beneficial agent is included within and / or coated on the porous clay particles. The clay is preferably a clay of the smectite class. Preferred clays are kaolin, bentonite, or china clay.

[0025] Clay is a finely ground natural rock or soil material. Based on physical and chemical properties, these clays are further classified into many clay mineral groups. For example, the structure of kaolinite is a tetrahedral silica sheet alternating with an octahedral alumina sheet. The charges within the structural unit are balanced. The common molecular formula for kaolinite groups is Al2Si2O5(OH)4.

[0026] Bentonite has the ability to form a thixotropic gel with water, the ability to increase its volume by 12 to 15 times its dry bulk upon absorption of a large amount of water, and a high cation exchange capacity. These cations are exchangeable due to their weak bonds and, together with the broken bonds (about 20% of the exchange capacity), give montmorillonite a fairly high (about 100 meq / 100 g) cation exchange capacity, which is hardly affected by the particle size.

[0027] These clays can be procured from companies such as English India Clays (EICL), Clariant, Ashapura Minehem Ltd., Shree Ram Minerals.

[0028] The porous clay particles are included in the range of 1 to 25%, preferably 2 to 10% by weight of the soap bar composition.

[0029] Subsequently, the porous clay particles incorporated with / water-soluble skin-beneficial agent-coated with a water-soluble skin-beneficial agent are further coated with a hydrophobic material selected from wax or petrolatum, preferably petrolatum.

[0030] Any of the following types of wax, namely, microcrystalline wax, beeswax or carnauba wax can be used. Microcrystalline wax is a petroleum-derived plastic material different from paraffin wax in that it has much finer and less distinguishable crystals, and a relatively high melting point and viscosity. The melting point range is higher than that of paraffin wax and ranges from 63° to 93 °C for commercially available grades. Chemically, microcrystalline wax consists of saturated aliphatic hydrocarbons.

[0031] Beeswax is a natural wax produced by honeybees of the genus Apis (Apis). Beeswax is a tough wax formed from a mixture of several chemical compounds. The approximate chemical formula of beeswax is C 15 H 31 COOC 30H 61 It is so. Its main components are palmitic acid esters, palmitoleic acid esters, and oleic acid esters of long-chain (30 - 32 carbons) fatty alcohols. Beeswax has a relatively low melting point range of 62 - 64°C.

[0032] Carnauba, also called Brazil wax or palm wax, is the wax of palm leaves. Carnauba consists mostly of aliphatic esters, diesters of 4-hydroxycinnamic acid, ω-hydroxycarboxylic acids, and fatty alcohols. This compound is mainly derived from acids and alcohols in the range of C26 - C30. The characteristics of carnauba wax are the high content of diesters and methoxycinnamic acid. The melting point is generally in the range of 82 - 86°C.

[0033] Petrolatum, also known as yellow petrolatum, is a purified mixture of semi-solid hydrocarbons obtained from petroleum having a carbon chain length of 25 or more. Yellow petrolatum is excellent in moisture retention and has a melting point of about 37°C. Yellow petrolatum is colorless or light yellow (when not highly distilled), translucent, and odorless and tasteless when pure. Yellow petrolatum is insoluble / immiscible in water. Petrolatum is generally also known as yellow petrolatum. The preferred petrolatum for use in the present invention has a slip melting point in the range of 45 - 75°C. The hydrophobic phase may also contain relatively small amounts of other hydrophobic materials such as fatty acids, triglycerides, or silicones.

[0034] The hydrophobic material is contained in the range of 0.1 - 10% by weight of the clay particles.

[0035] Other anionic surfactants may be included in the soap bar composition of the present invention. The other anionic surfactants are preferably selected from alkyl ether sulfates, primary alkyl sulfates, secondary alkyl sulfonates, alkyl benzene sulfonates or ethoxylated alkyl sulfates. Preferred anionic surfactants other than soap for the soap bar composition of the present invention are alkyl ether sulfates, preferably those having 1 to 3 ethylene oxide groups, which are derived from either natural or synthetic sources, and / or sulfonic acids. Sodium lauryl ether sulfate is particularly preferred. Alkyl polyglucosides, preferably those having a carbon chain length of C6 to C16, may also be present in the composition. Preferred compositions may contain other known ingredients such as fragrances, pigments, preservatives, softeners, sunscreens, gelling agents and thickeners. The selection of these ingredients depends largely on the form of the composition. Water is the preferred carrier. When present, water is preferably present in the range of at least 1%, more preferably at least 2%, and even more preferably at least 5% of the weight of the composition. When water is the carrier, the preferred cleansing composition contains 10 to 40% by weight, more preferably 12 to 25% by weight of water.

[0036] Soap bar compositions are preferably prepared using conventional grinding and extrusion soap manufacturing processes. In the grinding and extrusion route, the soap is prepared to have a high water content and then spray dried to reduce the water content and cool the soap, after which other ingredients are added and then the soap is extruded through an extruder and cut and molded to prepare the final soap bar. Ground and extruded soaps generally have a high TFM in the range of 60 - 80 weight percent. Alternatively, the soap is prepared by a relatively dry mixing method in a plowshare mixer and then extruded by conventional methods. Ground and extruded soap bars are also known as extruded soap bars. They are composed of a very large number of different types of soaps. Most soap compositions contain both water-insoluble and water-soluble soaps. Their structure generally features a brick and mortar type structure. The insoluble soap (referred to as brick) usually consists of relatively high-chain C16 and C18 soaps (palmitate and stearate soaps). They are generally included in the soap bar to provide a structuring effect, i.e., to bring about the shape of the bar. The soap bar also consists of water-soluble soaps (acting as mortar) which are generally unsaturated C18:1 and 18:2 sodium soaps (oleate soaps) combined with short-chain fatty acids (generally C8 - C12 or even up to C14 soaps). The water-soluble soaps generally aid in cleaning.

[0037] In the soap bar composition of the present invention, the coated clay particles for inclusion in the soap bar composition of the present invention are generally prepared by the process described below.

[0038] The aqueous solution of the beneficial agent is slowly added to the dry porous clay medium and mixed for several minutes, for example, about 5 minutes to 1 hour. Subsequently, the particles coated with the beneficial agent are dried in an oven to substantially reduce the moisture content to a low level, for example, about 1 to 5 wt%, so as to be free-flowing. Particle aggregation may occur after this coating step. The aggregated particles are broken down to the desired fine powder size in a particle grinder. The resulting coated powder is mixed in a solution mixture of a desired organic solvent in which the hydrophobic material is solubilized. The solvent is recovered from the powder solution via a solvent recovery extraction process, and the coated clay particles are dried to a free-flowing state.

[0039] The present invention also relates to a method for delivering a skin beneficial agent to the skin, which includes the step of applying the composition of the present invention to a desired skin surface. Subsequently, after a specified amount of time, the soap is substantially removed from the surface. Usually, people spend about 10 seconds to 2 minutes washing a body part, and it is predicted that the desired deposition of the active substance will occur within this time frame. The washing time is preferably 10 seconds to 1 minute, and more preferably 10 seconds to 30 seconds. The removal of the composition from the surface may be achieved by wiping the composition from the surface using a suitable wipe. Alternatively, and more preferably, it may be achieved by rinsing the surface with water so that the soap is substantially gone. The composition is usually applied to the desired skin surface after diluting the composition with water. The composition can be diluted with water to a concentration of 1 to 50%, preferably 2 to 20%, of the weight of the diluted solution.

[0040] Hereinafter, the present invention will be described with the help of the following non-limiting examples.

[0041] [Examples] Soap bars as shown in Table - 1 below were prepared: Example A: Control Example B: Bar containing uncoated clay Example C: Bar containing clay + PDADMAC Example 1: Bar containing PDADMAC clay coated with petrolatum (according to the present invention)

[0042] The following process is used to coat clay with PDADMAC and then with petrolatum: An aqueous solution of polydiallyldimethylammonium chloride is sequentially added to a dry porous clay medium (Supershine Plus Kaolin, EICL, India) and mixed for about 45 minutes. Subsequently, the particles coated with the beneficial agent are dried in an oven to substantially reduce the moisture to a low level of about 2%. Any aggregated particles are broken down to the desired fine powder size in a particle mill. The resulting coated powder is mixed in a solution mixture of the organic solvent hexane in which petrolatum is solubilized. The solvent is separated from the coated clay particles and dried to a free-flowing state.

[0043]

Table 1

[0044] After 6 hours of washing, the soap bar was tested for the regrowth of Staphylococcus aureus (S. aureus) on Vitro skin.

[0045] The procedure used to measure this was as follows: a) A 5×5 cm 2 sterile Vitro skin was placed in a Petri dish and washed with 2 ml of sterile water before any treatment. After 10 minutes, the water was removed and the skin was kept in a new Petri dish to dry. b) The skin was dried for 20 minutes. The skin was not overly dry and a wet half-cut bar was rubbed horizontally over the test area for 15 seconds. After 15 seconds, 1 ml of water was added to the VITRO-SKIN using a pipette and spread using an L-spreader to cover the test area in horizontal and vertical patterns for 45 seconds (this caused foaming of the soap). c) After 1 minute (45 + 15 seconds), hold the vitro-skin with one hand at a 45-degree angle and pour distilled water (about 20 - 30 ml) onto the skin with the other hand. No soap residue should remain on the skin. Then, dry the skin for 30 minutes. d) After 30 minutes of drying, add 100 μl of a 10 6 - colony bacterial inoculum (Staphylococcus aureus) and spread it using an L-shaped spreader. Allow the bacteria to adsorb well onto the skin surface and dry. e) Place the treated skin on a TSA plate and incubate the plate in an incubator at 37 degrees for 6 hours. After 6 hours, immediately add the treated skin to a 9 ml BPB neutralizer tube and shake vigorously for 3 minutes using a Griffin shaker to remove the bacteria from the skin. After performing a 10-fold serial dilution, plate it onto TSA medium.

[0046] Summarize the remaining log cfu / ml in Table - 2 below:

[0047]

Table 2

[0048] The data in Table - 2 above shows that the soap bar according to the present invention (Example - 1) is far more effective than soap bars (Examples B and C) prepared to have the same components but without the desired coating configuration.

Claims

1. (a) 40 to 80% soap; (b) Porous clay particles coated with a water-soluble beneficial agent having a water retention capacity in the range of 10 to 50% by weight and a solubility in water at 25°C of at least 0.001% by weight, and further coated thereon with a hydrophobic material selected from wax or petrolatum, a soap bar composition for enhancing the delivery of a water-soluble beneficial agent.

2. The soap bar composition according to claim 1, wherein the water-soluble beneficial agent is selected from at least one of an antimicrobial cationic active substance; a water-soluble vitamin or a derivative thereof; a water-soluble sunscreen agent; an α-hydroxy acid or a β-hydroxy acid; or a water-soluble alkali metal salt or a water-soluble alkaline earth metal salt.

3. The antimicrobial cationic active substance contains polydiallyldimethylammonium chloride (PDADMAC), The water-soluble vitamin contains vitamin B3, The α-hydroxy acid contains lactic acid, The soap bar composition according to claim 2, wherein the water-soluble alkaline earth metal salt contains calcium chloride.

4. The soap bar composition according to any one of claims 1 to 3, wherein the water-soluble beneficial agent is contained in an amount of 1 to 20% by weight of the weight of the porous clay particles.

5. The soap bar composition according to any one of claims 1 to 4, wherein the hydrophobic material is petrolatum.

6. The soap bar composition according to any one of claims 1 to 5, wherein the porous clay particles are derived from smectite clay.

7. The soap bar composition according to claim 6, wherein the smectite clay is kaolin, bentonite or china clay.

8. The soap bar composition according to any one of claims 1 to 7, containing 0.1 to 10% by weight of a hydrophobic material of the porous clay particles. Claim 9 The soap bar composition according to any one of claims 1 to 8, wherein the porous clay particles are contained in an amount of 1 to 25% by weight of the soap bar composition. Claim 10 A method for producing coated clay particles for use in the soap bar composition according to any one of claims 1 to 9, comprising the following: (a) mixing the porous clay particles with an aqueous solution of the water-soluble beneficial agent; (b) drying the porous clay particles to substantially remove moisture; (c) mixing the dried porous clay particles with a solution mixture of an organic solvent and the hydrophobic material; (d) separating the porous clay particles from the solution mixture and drying the porous clay particles to prepare the coated clay particles The production method comprising. Claim 11 The production method according to claim 10, wherein the organic solvent is selected from hexane, heptane, octane or carbon tetrachloride. Claim 12 A method for delivering a water-soluble active substance onto the skin, comprising the step of rinsing the skin with water so that the soap is substantially removed after washing the skin with a solution of the soap bar composition according to any one of claims 1 to 9.

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