EP2892991B1

EP2892991B1 - Soap composition

Info

Publication number: EP2892991B1
Application number: EP13745052.4A
Authority: EP
Inventors: Sujatha Jayaraman; Shanthi APPAVOO; Vidula Iyer
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2012-09-07
Filing date: 2013-08-01
Publication date: 2016-03-02
Anticipated expiration: 2033-08-01
Also published as: ZA201501542B; CN104736687A; WO2014037167A1; BR112015004813A2; IN2015MN00414A; BR112015004813B1; EP2892991A1; BR112015004813A8; CN104736687B

Description

FIELD OF INVENTION

The present invention relates to a soap composition, particularly to a personal wash composition with synergistic antibacterial activity.

BACKGROUND AND PRIOR ART

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
Personal wash compositions are available in various forms such as soap bars, transparent soap bars including cast-bars, liquid soaps including liquid hand wash compositions, creams and gel based products. Commercial soap compositions have one or more "soaps", which has the meaning as normally understood in the art; salts of mono-carboxylic fatty acids. The counterions of the salts are generally sodium, potassium, ammonium or alkanolammonium ions, but other suitable ions known in the art may also be used. Compositions based on soaps, i.e. soap bars generally contain anywhere from 15 to 80% by weight alkali metal salt of fatty acids, depending on whether the soap composition is in solid or liquid form, which accounts for the total fatty matter (TFM), the remainder being water (about 10-20%) and other ingredients such as metal ion chelators, colour, perfume, preservatives etc. Structurants and fillers are also frequently added to such compositions in small amount to replace some of the soap, while retaining the desired properties of the product. Soap bars having TFM content of about 70 are called "toilet soaps", whereas those having TFM of about 40 are called "bathing bars".
There are several types of microorganisms, such as bacteria, virus and moulds, present in the atmosphere, some of which prefer to live and multiply on human skin. Some of these organisms that reside on human skin, cause undesirable conditions such as body odour, pimples and acne, which are cosmetically unacceptable to people. These conditions are further aggravated by hot and humid climatic conditions. One way to get rid of these microorganisms residing on the skin is to wash them off, while having a bath or while washing hands, preferably using a washing composition, such as soap.
Soaps per-se, are also known to possess antimicrobial properties. In addition, specially formulated germicidal soap compositions are also known in the art, which are used to treat serious skin disorders like scabies. To provide antibacterial benefits through soap compositions, germicides or antibacterial agents such as triclosan (i.e., 2,4,4'-trichloro-2'-hydroxy-diphenylether; TCN) and triclocarbanilide; TCC are known and have been used. It has also been desired that antimicrobial action is provided in short time scales at which cleaning is carried out by most people which is of the order of less than one minute and sometimes less than half a minute. Antimicrobial compositions comprising combinations of essential oil actives, based on which soaps have been are prepared, are also known and one such composition is disclosed in WO2010046238 .
Among the fatty acids, lauric acid generally derived from coconut oil has been used in soap making. Coconut oil is generally used at about 20% of the total oil/ fatty acid mixture and such an amount of coconut oil leads to the soap composition having about 10% lauric acid. Compositions comprising high amount of lauric acid soap have been reported in WO07065538 .
The present inventors have surprisingly found that a soap composition comprising a specific amount of lauric acid soap along with specific antimicrobial actives provides superior antimicrobial activity due to synergistic interaction of the soap and the actives.
It is thus an object of the present invention to provide enhanced antimicrobial properties from soaps, at considerably lower concentration of antimicrobial actives than known before.
It is another object of the present invention to provide the enhanced antimicrobial properties this at relatively short time scales.
It is yet another object of the present invention to provide a personal wash composition comprising ingredients, which are readily available and can be easily incorporated in the composition thereby keeping costs low.

SUMMARY OF THE INVENTION

The present invention according to a first aspect relates to a soap composition comprising:

a) 15 to 80 % by weight of soap;
b) 0.01 to 5 % by weight of one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol;
wherein 12 to 50% by weight of said soap is a salt of lauric acid;
wherein the essential oil active is selected from the group consisting of linalool, nerol, geraniol, terpineol, thymol, eugenol and mixtures thereof.

Preferably, the salt of lauric acid is sodium or potassium laurate.
According to a second aspect of the invention, there is provided a method of disinfecting a surface comprising the steps of

a. applying a composition according to the invention on to the surface; and
b. removing the composition from the surface.

In a third aspect, the invention provides the use of a composition according to the invention for improved hygiene.

DETAILED DESCRIPTION OF THE INVENTION

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 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". Unless specified otherwise, 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 an antimicrobial composition as used herein, is meant to include a composition for cleaning and disinfecting topical areas e.g. skin and/or hair of mammals, especially humans. Such a composition, as per the present invention comprises soap and is therefore generally a rinse off cleaning composition which may additionally be used for improving the appearance, for odour control or for general aesthetics. The composition of the present invention may be in the form of a liquid but may be modified to include a lotion, cream, foam or gel, or toner, or applied with an implement or via a face mask, pad or patch. Preferably the composition is in the solid form. "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). 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 disinfection and cleaning.
The composition of the invention may be formulated in any one of the product forms listed hereafter, each of which is defined below. By a soap bar is meant a composition in a shaped solid form that comprises a soap i.e. a salt of fatty acid. Soap bars may be prepared by the milled and plodded route or by the melt cast route. By a liquid personal cleaning composition is meant a composition in liquid form that is used for various personal cleaning applications like hand washing, body washing, face washing or cleaning of hair
Antibacterial soap compositions and personal wash compositions are well known in the art. Such compositions are available in various product formats such as toilet soaps, bathing bars, hand-wash liquids, body-wash liquids and antibacterial soap wipes. Increasing awareness about hygiene, coupled with the continuously increasing national and international standards of urban and rural hygiene have caused a large demand for such products. The usage of antibacterial soap compositions is not only limited to people living in rural areas, but has also become a part of the everyday hygiene program of people living in modern cities.
Soaps are defined as salts of fatty acids, which are prepared by neutralizing the corresponding fatty acid or oil with a base, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide or triethylamine. Alkali metal salts of carboxylic acids are prepared by neutralizing the corresponding fatty acid or by treating an oil (triglyceride) having the required fatty acid composition with an alkali. The latter process is commonly known as saponification. The alkali used is either the corresponding metal hydroxide or the metal carbonate. Coconut oil and palm kernel oil are rich in lauric acid and therefore could also be used as precursors of lauric salts used according to the invention. Alkali metal salts of the invention are preferably selected from sodium salts, potassium salts or a mixture thereof. If sodium salts are used as described in the invention the resultant composition can be used to prepare solid soaps. Potassium salts, on the other hand, lead to a softer product, which is especially preferred when the desired product is a liquid soap. A mixture of sodium and potassium salts leads to products with an intermediate degree of hardness/softness and a person skilled in the art, depending upon the requirement, can suitably balance this ratio.
Soaps per-se have some antimicrobial activity, which is further enhanced by use of the antimicrobial actives as per the present invention.
The soap in the soap compositions according to the invention typically comprise a fraction that consists of laurate soaps and another fraction that consists of non-laurate soaps. While coconut oil or coconut fatty acid serve as precursors for laurate soap the saponification of a distilled fatty acid blend, leads to the generation of the non-laurate soap component in the soap composite.
Distilled fatty acid (DFA) is a mixture of C14 to C18 fatty acids, which include myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. Personal wash compositions are typically made by using combinations of coconut oil soaps and DFA soaps in the ratio from 80:20 to 20:80 parts by weight. This ratio can be altered to achieve desired results.
The present inventors have found and demonstrated that a surprising synergy exists in a composition containing a specific amount (15 to 50%) of laurate soap by weight of total soap in combination with specific antimicrobial actives. These two, in combination exhibit superior antimicrobial efficacy that provides greater benefits to the user.
The present invention relates to a soap composition comprising 15 to 80% by weight soap and 0.01 to 5% of one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol; wherein 12 to 50% by weight of said soap is a salt of lauric acid.
The composition of the present invention comprises from 15 to 80% by weight of soap. When the soap composition is in solid form it preferably comprises 40 to 80%, more preferably from 55 to 76 % by weight of soap. When the composition is in the liquid form, it preferably comprises 15 to 30% soap, more preferably 15 to 20% soap. According to the invention, the salt of lauric acid is preferably from 12 to 25% by weight of the total amount of soap present in the composition.
Lauric acid is a monocarboxylic fatty acid having 12 carbon atoms. The IUPAC name of Lauric acid is "Dodecanoic acid". It is found, occurring in nature in palm kernel oil and coconut oil, to the extent of about 50%. The term "salt of lauric acid" is used to indicate derivatives of lauric acid that is neutralized using an alkali/alkaline material. Preferably, the salt is a lithium, sodium, potassium, calcium, magnesium, ammonium, triethylammonium or triethanolammonium salt; more preferably the salt is sodium or potassium laurate. A suitable combination of sodium and potassium salts can also be used, without diverting from the scope of the invention.
The term total fatty matter, usually abbreviated to TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soaps with respect to the total composition without taking into account the accompanying cations.
The soap can be obtained by saponifying a fat/oil and/or a fatty acid. The fats or oils generally used in soap manufacture may be such as tallow, tallow stearines, palm oil, palm stearines, soya bean oil, fish oil, caster oil, rice bran oil, sunflower oil, coconut oil, babassu oil, palm kernel oil, and others. In the above process the fatty acids are derived from oils/fats selected from coconut, rice bran, groundnut, tallow, palm, palm kernel, cotton seed, soybean, castor etc.
The fatty acid soaps can also be synthetically prepared (e.g. by the oxidation of petroleum or by the hydrogenation of carbon monoxide by the Fischer-Tropsch process). Resin acids, such as those present in tall oil, may be used. Naphthenic acids are also suitable.
Tallow fatty acids can be derived from various animal sources and generally comprise about 1-8% myristic acid, about 21-32% palmitic acid, about 14-31% stearic acid, about 0-4% palmitoleic acid, about 36-50% oleic acid and about 0-5% linoleic acid. A typical distribution is 2.5% myristic acid, 29% palmitic acid, 23% stearic acid, 2% palmitoleic acid, 41.5% oleic acid, and 3% linoleic acid. Other similar mixtures, such as those from palm oil and those derived from various animal tallow and lard are also included.
Coconut oil refers to fatty acid mixtures having an approximate carbon chain length distribution of 8% C8, 7% C10, 48% C12, 17% C14, 8% C16, 2% C18, 7% oleic and 2% linoleic acids (the first six fatty acids listed being saturated). Other sources having similar carbon chain length distributions, such as palm kernel oil and babassu kernel oil, are included within the term coconut oil.
The soap composition of the invention comprises 0.01 to 5% of one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol. The essential oil actives are selected from the group consisting of linalool, nerol, geraniol, terpineol, thymol, and eugenol. More preferred actives are selected from the group consisting of terpineol, thymol, and eugenol. Further more preferred actives are terpineol or thymol. Most preferred is a mixture of terpineol and thymol.
Details of the more preferred essential oil actives are given herein below.

Thymol

The structure of thymol is given below:
The composition of the invention comprises preferably 0.01 to 5%, more preferably 0.01 to 1%, further more preferably 0.01 to 0.4%, by weight thymol, provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol. Thymol may be added to the composition in purified form. Alternatively, thyme oil or thyme extract comprising thymol may be added to the composition, while ensuring that thymol is present in the desired concentration in the composition of the present invention. Thyme oil or thyme extract is obtained from the thyme plant. Thyme plant refers to a plant belonging be genus Thymus and includes but is not limited to the following species: Thymus vulgaris, Thymus zygis, Thymus satureoides, Thymus mastichina, Thymus broussonetti, Thymus maroccanus, Thymus pallidus, Thymus algeriensis, Thymus serpyllum, Thymus pulegoide, and Thymus citriodorus.

Terpineol

The structure of a terpineol compound is given below:
The terpineol is preferably selected from alpha-terpineol, beta-terpineol, gamma-terpineol or mixtures thereof. It is particularly preferred that the terpineol is alpha-terpineol. Terpineol may be added to the antimicrobial composition in purified form. Alternatively pine oil comprising terpineol may be added to the antimicrobial composition while ensuring that terpineol is present in the desired concentration in the composition of the present invention. The composition preferably comprises 0.01 to 5%, more preferably 0.02 to 5%, further more preferably 0.03 to 1%, and even more preferably 0.04 to 0.6% by weight of terpineol, provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol.

Eugenol

Eugenol is an allyl chain-substituted guaiacol. It is generally extracted from certain spices like clove or cinnamon. Eugenol has been used as a perfumery component, in preparing flavours, as an antiseptic or as a local anesthetic. The composition of the invention preferably comprises 0.01 to 5%, preferably 0.02 to 1%, more preferably 0.03 to 0.4%, by weight of eugenol, provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol.
Eugenol has the structure:

Geraniol

The structure of the geraniol compound is given below:
Geraniol is a monoterpenoid and an aliphatic alcohol. It is the primary component of rose oil, palmarosa oil and citronella oil. It has a rose-like odour and is commonly used in perfumes. The composition of the invention preferably comprises 0.01 to 5%, preferably 0.02 to 1%, more preferably 0.03 to 0.4%, by weight of geraniol, , provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol.

Linalool

The structure of the linalool compound is given below:
Linalool is a monoterpenoid and an aliphatic alcohol. Over 200 species of plants produce linalool, mainly from the families Lamiaceae (mints, scented herbs), Lauraceae (laurels, cinnamon, rosewood), and Rutaceae (citrus fruits), but also birch trees and other plants, from tropical to boreal climate zones. It has a sweet, floral odour and is commonly used in perfumes. The composition of the invention preferably comprises 0.01 to 5%, preferably 0.02 to 1%, more preferably 0.03 to 0.4%, by of weight linalool, provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol.
The composition may preferably comprise a combination of thymol and terpineol in any of the preferred concentrations as specified above for thymol and terpineol, respectively. For instance, the composition may preferably comprise a mixture of 0.01 to 0.6% thymol and 0.02 to 1.5% terpineol by weight of the composition. The composition of the present invention most preferably comprises a mixture of 0.01 to 0.4% eugenol, 0.01 to 0.6% thymol, and 0.02 to 1.5% terpineol by weight of the composition.

PCMX

The structure of the PCMX compound is given below:
Para-chloro-m-xylenol, which is also called PCMX or 4-chloro-3,5-dimethylphenol is an antimicrobial chemical compound used to control bacteria, algae and fungi in various products such as soaps, paints, and adhesives. Its antibacterial action is due to disruption of cell membrane potentials. It has a faint phenolic odour. The composition of the invention preferably comprises 0.01 to 5%, preferably 0.02 to 1%, more preferably 0.03 to 0.4%, by weight PCMX, provided that the soap composition of the invention comprises 0.01 to 5 % by weight of the one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol.

Additional ingredients

The composition, according to the invention, can optionally comprise detergent actives, which are generally chosen from anionic, nonionic, cationic, amphoteric or zwitterionic detergent actives. It is preferred that if non-soap detergents are used in the composition of the invention, the non-soap detergent is chosen from anionic or nonionic detergent active. Synthetic detergents contain a relatively polar hydrophilic group and a relatively non-polar hydrophobic group.
The contemplated water soluble anionic detergent surfactants are the alkali metal (such as sodium and potassium) salts of the higher linear alkyl benzene sulfonates and the alkali metal salts of sulfated ethoxylated and unethoxylated fatty alcohols, and ethoxylated alkyl phenols.
Specific sulfated surfactants which can be used in the compositions of the present invention include sulfated ethoxylated and unethoxylated fatty alcohols, preferably linear primary or secondary monohydric alcohols with C₁₀-C₁₈, preferably C₁₂-C₁₆, alkyl groups and, if ethoxylated, on average about 1-15, preferably 3-12 moles of ethylene oxide (EO) per mole of alcohol, and sulfated ethoxylated alkylphenols with C₈-C₁₆ alkyl groups, preferably C₈-C₉ alkyl groups, and on average from 4-12 moles of EO per mole of alkyl phenol.
The preferred class of sulfated ethoxylated surfactants are the sulfated ethoxylated linear alcohols, such as the C₁₂-C₁₆ alcohols ethoxylated with an average of from about 1 to about 12 moles of ethylene oxide. A most preferred sulfated ethoxylated detergent is made by sulfating a C₁₂-C₁₅ alcohol ethoxylated with 3 moles of ethylene oxide.
Specific nonionic surfactants which can be used in the compositions of the present invention include ethoxylated fatty alcohols, preferably linear, primary or secondary monohydric alcohols with C₁₀-C₁₈, preferably C₁₂-C₁₆, alkyl groups and on average about 1-15, preferably 3-12 moles of ethylene oxide (EO) per mole of alcohol, and ethoxylated alkylphenols with C₈-C₁₆ alkyl groups, preferably C₈-C₉ alkyl groups, and on average about 4-12 moles of EO per mole of alkyl phenol.
The preferred class of nonionic surfactants compounds are the ethoxylated linear alcohols, such as the C₁₂-C₁₆ alcohols ethoxylated with an average of from about 1 to about 12 moles of ethylene oxide. A most preferred nonionic detergent is a C₁₂-C₁₅ alcohol ethoxylated with 3 moles of ethylene oxide.
Mixtures of the foregoing synthetic detergent type of surfactants, e.g., of anionic and nonionic, or of different specific anionic or nonionic surfactants, may be used to modify the detergency, lather characteristics, and other properties of the composition. For example, a mixture of different fatty alcohols of 12 to 15 carbon atoms may be ethoxylated, directly sulfated, or sulfated after ethoxylation, a fatty alcohol may be partially ethoxylated and sulfated, or an ethoxylated fatty acid may be partially sulfated to yield a mixture of anionic and nonionic surfactants or different specific anionic or nonionic surfactants. When present, surfactants are preferably in the range of 5-50% by weight, more preferably from 8 to 30%, further more preferably from 10 to 25% by weight of the composition.
Benefit agents e.g. moisturisers, emollients, sunscreens, or anti ageing compounds may be incorporated in the composition of the invention. Examples of moisturisers and emollients include humectants like polyols, glycerol, cetyl alcohol, carbopol, ethoxylated castor oil, paraffin oils, lanolin and its derivatives. Silicone compounds such as silicone surfactants like DC3225C (ex Dow Corning) and/or silicone emollients, silicone oil (DC-200 ex Dow Corning) may also be included. Sun-screens such as 4-tertiary-butyl-4'-methoxy-dibenzoylmethane (available under the trade name PARSOL 1789 from Givaudan) and/or 2-ethyl hexyl methoxy cinnamate (available under the trade name PARSOL MCX from Givaudan) or other UV-A and UV-B sun-screens may also be incorporated. Water soluble glycols such as propylene glycol, ethylene glycol, glycerol, may be employed at levels upto 10%. Other additives such as one or more water-insoluble particulate materials e.g. polysaccharides such as starch or modified starches and cellulose may be incorporated. Minor additives include metal ion chelators or sequestrants, colour, preservatives and perfumes, may optionally be incorporated. The soap composition of this invention may also contain varying quantities of compatible adjuvants. Typical examples of such compatible adjuvants are fillers and pigments such as titanium dioxide, diatomaceous earth, any of various coloured pigments, dyes, fragrances, and optical brighteners.
The composition can be made in solid form such as bars, flakes, chips, or powders or in liquid form, such as hand-wash and body wash compositions. The composition can be formed into framed (cast) soap or milled soap bars in accordance with the general procedure of the soap making art.

Process for preparing soap bars

A process for making soap bars in accordance with one exemplary embodiment of the present invention will now be described.
The soap components of the soap bars may be manufactured by mixing a fatty acid or acids and at least one neutralizing agent in an open agitated reaction vessel at atmospheric pressure and heating to a temperature sufficient to melt the fatty acids, generally at least about 80°C to 90°C. The fatty acids include lauric acid and monocarboxylic fatty acids having alkyl chain lengths of 14 carbon atoms to 22 carbon atoms. Suitable neutralizing agents for manufacturing of the soap bars of the present invention include caustic solutions, for example, sodium bases such as NaOH. The neutralizing agent neutralizes the fatty acids, forming salts of the fatty acids (i.e., "soaps"), such as for example, sodium, potassium, ammonia or alkanolammonium salts. The neutralizing agent may be added in an amount less than the amount of the neutralizing agent required to fully neutralize the fatty acids. In one exemplary embodiment of the invention, about 95% of the required amount of neutralizing agent needed to fully neutralize the fatty acids may be added. The temperature preferably is maintained above about 80°C but below about 100°C.
Optionally at this point, the mixture may be analysed for free acid and the pH of the mixture manipulated accordingly. For example, the mixture may be titrated with NaOH using a pH indicator and, if necessary, the composition of the mixture may be manipulated so that a 10% aqueous solution of the resulting soap bar has a pH no greater than about 9. For example, if the pH is too acidic, more neutralizing agent may be added. Alternatively, if the mixture has a pH above about 9, more free fatty acids may be added to the composition. If free fatty acids are added, it is preferable that the free fatty acids have alkyl chains of 8 to 10 carbon atoms.
At this stage of the manufacturing process, the temperature of the reaction mixture may be raised to at least about 90°C, preferably from about 90°C to about 100°C, to evaporate a desired amount of water. Alternatively, the water may be evaporated before addition of an additional neutralizing agent or free fatty acid as described above. In one embodiment of the invention, the soap bar comprises no more than 25% water. Preferably, the soap bar comprises no more than 20% water. More preferably, the soap bar comprises no more than 15% water. When a desired amount of water has been removed from the soap component, the soap component may be cooled, followed by the addition of optional ingredients also may be added to the soap component using conventional methods. The resulting composition may be formed into soap bars, either by pouring the composition, in a molten state, into moulds, or, alternatively, by forming soap bars using conventional milling, plodding and/or stamping procedures as is well known in the art.

Method of disinfecting

According to a second aspect of the invention, there is provided a method of disinfecting a surface comprising the steps of

Preferably, the surface is skin. Thus, for example, a surface like the hands, face, body, or the oral cavity is contacted with the composition of the invention. Alternatively, the surface is any hard surface. Typically, such hard surfaces are surfaces that commonly require cleaning and preferably also require sanitisation or disinfection. Such surfaces may be found in many household or industrial environments, and may include for example kitchen and bathroom surfaces, table tops, floors, walls, windows, utensils, cutlery, and crockery. Such surfaces may be made from many different materials, including for instance plastics, wood, metal, ceramics, glass, concrete, marble, and painted surfaces.
The composition may be applied to the surface by any suitable means known to the skilled person. For instance, a suitable means may be pouring, dropping, spraying or wiping in case of liquid compositions.
Preferably, the method includes diluting or dissolving the composition with a suitable solvent, preferably water, before or whilst applying the composition to the surface. Such dissolving is preferred in particular in case the composition is a solid composition. Alternatively, solid compositions may also be directly spread, rubbed, or sprayed, e.g. in the form of a powder.
The method according to the first aspect of the present invention also includes the step of removing the composition from the surface. Here, removing the composition also encompasses partially removing the composition, because traces of the composition may remain on the surface. In many typical situations, including washing of the skin or hard-surface cleaning, it is acceptable or sometimes even desirable if part of the composition - in particular certain active ingredients - remains on the surface. Therefore, step b preferably involves removing at least 5%, more preferably at least 10%, even more preferably at least 25%, still more preferably at least 50% and yet more preferably at least 75% of the composition by weight. Preferably, the step of removing the composition comprises rinsing the surface with a suitable solvent or wiping the surface with a suitable wipe, more preferably, this step consists of rinsing the surface with a suitable solvent or wiping the surface with a suitable wipe. Alternatively, the removal step can also include evaporation of part of the composition, for example when the composition comprises volatile components, e.g. solvents.
A suitable medium for rinsing the surface is water but it could also be for example a mixture of water and alcohol. It is then rinsed preferably with sufficient amounts of water after a pre-determined period of time to remove any visible or sensory residue of the composition. Alternatively, an alcohol wipe or a water/alcohol impregnated wipe may be used to wipe the surface to be visibly free of the anti-microbial composition. The step of removing the composition (e.g. by rinsing or wiping the surface) is preferably started less than 5 minutes, more preferably less than 2 minutes, even more preferably less than 1 minute, still more preferably less than 30 seconds and yet more preferably less than 20 seconds after commencement of the step of applying the composition on the surface, because of the surprisingly fast antimicrobial action of the compositions according to the present invention. Even though partial microbial kill may be almost instantaneous upon application of the composition according to the invention, it is preferred that the step of removing the composition from the surface is started out at least 5 seconds, preferably at least 10 seconds, more preferably at least 15 seconds after commencement of the step of applying the composition on the surface, in order to effect optimal antimicrobial action. Combinations of these times into time intervals are preferred too. Therefore, it is particularly preferred that the step of removing the composition from the surface (i.e. step b) is started between 2 minutes and 5 seconds, more preferably between 1 minute and 10 seconds, even more preferably between 30 and 10 seconds and still more preferably between 20 and 15 seconds after commencement of the step of applying the composition on the surface (i.e. step a).
The method according to the invention preferably is a non-therapeutic method of disinfection.

Use according to the invention

The invention preferably provides for non-therapeutic benefits. Thus, for instance, the invention relates to use of an antimicrobial composition according to the present invention for faster reduction in viable microbial count.
Thus, according to the third aspect of the invention, there is provided use of a composition according to the invention for improved hygiene. Such use relates for example to use for reduction in viable microbial count, preferably fast reduction of viable microbial count. Thus, such use preferably is use in a method for disinfection.
Thus, there is provided use of a composition according to the invention for improved hygiene of surfaces of the human body. Such surfaces include e.g. skin, hands and the oral cavity. According to a preferred aspect, the invention relates to use of a composition according to the invention for improved hand hygiene. According to another preferred aspect, the invention relates to use of a composition according to the invention for improved oral hygiene.
To provide a more complete understanding of the present invention and not by way of limitation, reference is made to the following examples. However, one of ordinary skill in the art would appreciate that various modifications and changes can be made without departing from the scope of the present invention. Accordingly, the examples are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention.

EXAMPLES

Example A, B and Example -1: Synergy between sodium laurate and antimicrobial active

Compositions as shown in Table -1 were prepared and tested for antibacterial activity using the procedure as summarised below.

Protocol: Contact kill Assay (15spec contact kill)

The test bacteria E.coli ATCC 10536 was grown overnight in TSA plate (Difco - 40 grams per liter) (gpl) at 37°C for 16 - 18 hrs. The cell density was adjusted to get the final count of 10⁸ cfu/ml (0.8 OD at 620 nm). 9ml of the test solution was taken in a sample container and 1ml of processed culture was added to it. After 15 seconds of contact time, 1ml of the above mixture was immediately neutralized in D/E broth (Difco - 39gpl). Serial dilution was done in D/E broth and plated on TSA (Difco - 40gpl) in duplicates. In case of the control, 1 ml of test culture was added to 9 ml of saline and was serially diluted and plated on TSA. After solidification, the plates were incubated at 37°C for 48 hrs. The residual colonies were counted after 48hrs of incubation and efficacy was calculated by comparing with control. Log reduction is calculated by subtracting the log value of test solution from the culture control. Table -1

Example Composition Log reduction

A 0.0625% terpineol + 0.025% thymol 0.17

B 0.5% sodium laurate 0.33

1 0.0625% terpineol + 0.025% thymol + 0.5% sodium laurate 7.22
The data in Table 1 above is evidence that there is synergistic antimicrobial activity between a mixture of thymol and terpineol with sodium laurate at a low concentration where a mixture of thymol and terpineol have low antimicrobial activity.

Example C, D and Example 2 to 5: Synergy between sodium laurate and antimicrobial active in the presence of soap

Soap compositions containing 70% total soap were prepared. The composition comprised 0.5% terpineol and 0.2% thymol. The amount of sodium laurate as a % of total soap is listed in Table - 2 below. The procedure used to measure the antibacterial activity was the same as used for Example - 1. The data is summarised in Table - 2 below.

Table -2

Example	Antimicrobial active	Sodium laurate (as wt% of total soap)	Log reduction
C	Not present	9.2	0.29
D	Present	9.2	2.58
2	Present	13.7	4.16
3	Present	18.3	5.20
4	Present	20.1	5.31
5	Present	22.8	7.9

The data in Table -2 above indicates that when antimicrobial active was not used (Example C) or when amount of sodium laurate was outside the claimed range, the antimicrobial activity was low. However, when the amount of sodium laurate was within the claimed range, excellent antimicrobial activity was obtained.

Examples E to I and 6 to 9: Demonstration of the synergy of other antimicrobial actives with sodium laurate

Various other antimicrobial actives as shown in Table -3 were used together with sodium laurate and the antimicrobial activity was measured using the same procedure as used in Example -1. The data is summarised in Table - 3.

Table -3

Example	Antimicrobial Active (wt%)	Sodium laurate (wt%)	Log reduction
E	Not present	0.5%	1.04
F	p-chloro meta xylene (0.1%)	Not present	0.15
6	p-chloro meta xylene (0.1%)	0.5%	7.51
G	Geraniol(0.1%)	Not present	0.49

7	Geraniol (0.1%)	0.5%	7.51
H	Nerol (0.1%)	Not present	0.52
8	Nerol (0.1%)	0.5%	7.84
I	Linalool (0.1%)	Not present	0.26
9	Linalool (0.1%)	0.5%	7.84

The data in Table -3 above indicates that use of either sodium laurate alone (Example E) or use of certain antimicrobial actives claimed in the invention alone (Examples F to I) do not give good antimicrobial activity. However a combination of these (Examples 6 to 8) gives synergistic antimicrobial activity.

Examples J to W: Examples to show lack of activity when surfactants other than sodium laurate were used

Various other anionic surfactants (including various soap actives) were used along with antimicrobial actives (terpineol at 0.05% and thymol at 0.02%) as shown in Table - 4 but none exhibited the activity that salt of lauric acid has demonstrated. The data in Table - 4 was conducted using the same procedure as for Example -1.

Table - 4

Example	Antimicrobial Actives	Surfactant (wt%)	Log reduction
J	Present	Not present	0.13
K	Not present	0.4% sodium laurate	0.04
10	Present	0.4% sodium laurate	5.57
L	Not present	0.5% sodium palmitate	0.28
M	Present	0.5% sodium palmitate	0.69
N	Not present	0.5% sodium oleate	0.35
O	Present	0.5% sodium oleate	0.42
P	Not present	0.5% sodium myristate	0.32
Q	Present	0.5% sodium myristate	2.78
R	Not present	0.5% sodium capryllate	0.20
S	Present	0.5% sodium capryllate	0.16
T	Not present	0.5% sodium stearate	0.20
U	Present	0.5% sodium stearate	0.59
V	Not present	0.5% sodium lauryl sulphate	0.27
W	Present	0.5% sodium lauryl sulphate	1.27

The data in Table - 4 indicates that only use of sodium laurate along with antimicrobial active (Example 10) is able to give the synergistic activity while various similar soaps or anionic surfactant (Examples J to W) do not exhibit the high level of activity desired.
From the foregoing description, it becomes readily clear that a new and efficacious soap composition has been herein described and illustrated which fulfils some of the aforestated objectives.
The invention thus provides a synergistic soap composition that gives superior antibacterial activity.
Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

A soap composition comprising:
a) 15 to 80 % by weight of soap;

b) 0.01 to 5 % by weight of one or more antimicrobial actives selected from the group consisting of essential oil actives and para-chloro-m-xylenol;
wherein 12 to 50% by weight of said soap is a salt of lauric acid;
wherein the essential oil active is selected from the group consisting of linalool, nerol, geraniol, terpineol, thymol, eugenol and mixtures thereof.
A composition according to claim 1, wherein said antimicrobial actives are a mixture of terpineol and thymol.
A solid soap composition according to claim 1 or 2, wherein said soap is from 40 to 80 % by weight of said composition.
A liquid soap composition according to any one of the preceding claims, wherein said soap is from 15 to 30% by weight of said composition.
A composition according to any one of the preceding claims, wherein said salt of lauric acid is from 12% to 25% by weight of said soap.
A composition according to any of the preceding claims, wherein said salt of lauric acid is sodium or potassium laurate.
A method of disinfecting a surface comprising the steps of
a) applying a composition according to any one of claims 1 to 6 on to the surface; and

b) removing the composition from the surface.
A method according to claim 7, wherein the surface is a skin surface.
A method according to claim 7 or 8, wherein step (b) is started between 2 minutes and 5 seconds, more preferably between 1 minute and 10 seconds, even more preferably between 30 and 10 seconds and still more preferably between 20 and 15 seconds after commencement of step (a).
Use of a composition according to any one of claims 1 to 6 for improved hand hygiene.
Use of a composition according to any one of claims 1 to 6 for improved oral hygiene.