CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Application No. PCT/EP2018/071043, filed on Aug. 2, 2018, which claims priority to European Patent Application No. 17187899.4, filed on Aug. 25, 2017, the contents of which are incorporated herein in their entireties.

FIELD OF THE INVENTION

The present invention relates to an antimicrobial composition and more particularly to an antimicrobial composition at the pH of skin.

BACKGROUND OF THE INVENTION

People try to take good care of the external surfaces of their body as well as those of their pets to enable overall good health. Specific skin related issues that people care about include, good skin health free of infections, good skin tone and adequate moisturization. Oral cavity is another external surface that people try to take active care to maintain. They prefer their oral cavity including the gums and teeth to be free of problems like cavities, tartar, gingivitis, caries, bad breath also known as halitosis and plaque. Typically, people are also concerned with hair and scalp care. They generally prefer to have thick and long hair with minimum hair fall. Dandruff is a commonly occurring scalp problem for which a fungal microorganism has been implicated.

A good health for external surfaces including skin, oral cavity and scalp care are typically achieved by keeping them free of infections. One way to tackle infections is to treat it using antimicrobials after the infection has set in. Another approach is to leave a minimal amount of antimicrobial composition on the surface like e.g. skin of the hands, so that any invading microorganisms like e.g. bacteria are killed or inactivated so as to minimize spread of disease. Some bacteria likeEscherichia coli(E. coli) andStaphylococcus aureus(S. aureus) are commonly found on the human skin. These bacteria per se do not trigger a pathogenic effect whilst commonly present on the skin. However, when they enter the human body through cuts on the skin and through acts like ingestion, these bacteria become pathogenic. Therefore, keeping the external surface of the body like e.g. hand and scalp, free of bacteria helps in preventing them from entering the human body thereby achieving the desired hygiene.

Various germicidal compositions are disclosed that may be applied on to the skin of humans or warm-blooded animals. Some of these also discloses antimicrobial composition with polymers and carboxylic acids.

WO 00/13506 A2 (Alcide Corp.) discloses a freeze-resistance topical germicide for application to skin, such as the teats of a dairy cow. The germicide may be a one-part composition or a two-part system. The one-part disinfecting composition comprises an organic acid germicide and a non-esterifying antifreeze. The two-part system comprises a first part and a second part adapted to be mixed to yield the disinfecting composition. The first part comprises a metal chloride and a chlorite-stable antifreeze, and the second part comprises an organic acid germicide and a non-esterifying antifreeze, or an inorganic acid and either an alcohol or a non-esterifying antifreeze.

U.S. Pat. No. 6,436,444 (Ecolab Inc) discloses a mastitis control composition which comprises an aliphatic carboxylic acid having a chain length C6 to C12, an organic film forming agent e.g. PVA and polyvinyl acetate, rheology modifying material, an emollient, a surfactant and a buffer, and a chloride dioxide generating chemical such as sodium chlorite dissolved in an aqueous carrier. The base formulation in examples of U.S. Pat. No. 6,436,444 comprises carboxylic acid, such as nonanoic acid, octanoic acid, decanoic acid, a mixture of octanoic acid and decanoic aid and heptanoic acid, and PVA. To said base formulation an aqueous solution of sodium chlorite is added and pH of some of the compositions exemplified therein is less than 3.

U.S. Pat. No. 7,109,241 (Ecolab, Inc.) discloses an antimicrobial composition that can be used as a teat dip for milk producing animals. At least some embodiments of invention disclosed therein provide superior antimicrobial protection against mastitis causing organisms. The composition comprises a fatty acid containing 6 to 12 carbon atoms like e.g. heptanoic acid and a carrier medium including a freezing point depressant component. The compositions may further include rheology modifiers like e.g. hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylic acid (PAA) and polyvinyl pyrrolidone (PVP), to enhance viscosity or thicken the composition.

US2010/0234328 (Delaval Holdings) discloses an antimicrobial composition comprising an organic acid and an anionic surfactant. It relates to topical application of the composition on an animal. It also relates to a method of using an antimicrobial composition comprising organic acid and an anionic surfactant to reduce microbial concentrations that may relate to treatment or prevention of mastitis. Several examples of organic acids like e.g. lactic acid, salicylic acid, citric acid, hexanoic acid and octanoic acid, are disclosed. The composition may further comprise additives like barrier forming agents like e.g. hydroxyethyl cellulose, sodium alginate, xanthan gum, polyvinyl alcohol (PVA) and PVP.

US2013/224125 (Kolazi et al.) discloses a non-alcoholic or slightly alcoholic antibacterial mouthwash composition with improved antimicrobial efficacy wherein the composition comprises a water soluble matrix composite made of a water soluble polymer like PVP and a water soluble surfactant, at least one water immiscible or water insoluble antibacterial agent and optionally a weak carboxylic acid like e.g. citric acid, tartaric acid, lactic acid, benzoic acid and combinations thereof.

Various routes for improving the biocidal activity of soap based cleansing compositions have been suggested.

US2008014247A (Lu et al., 2008) discloses a composition having metal containing material, stearic acid and a pharmaceutically acceptable carrier to treat conditions caused by gram-positive, gram-negative, fungal pathogens and/or antibiotic-resistant bacteria. It further provides a method for inhibiting biofilm proliferation. The metal containing material can be silver.

U.S. Pat. No. 3,050,467 B1 (Horowitz et al. 1962) discloses an antimicrobial cleansing composition consisting essentially of a mixture of a water-soluble soap and a silver salt of partially depolymerized alginic acid. The composition provides synergestic antimicrobial activity.

However, addition of soap invariably increases the pH of the composition. High pH composition is harsh on the skin. Consumer also has a preference to use a formulation with pH close to that of human skin. Another problem is, most of the soap based antimicrobial compositions has to be applied for sufficiently long time to get the antimicrobial benefit. However most of the people especially kids do not wash their hand/skin for long enough.

Carboxylic acids are one of the known compounds used as antimicrobials. One of the preferred ways consumers make use of antimicrobial compositions is through personal washing and cleansing compositions that provide antimicrobial benefit. Consumers tend to prefer such personal washing and cleansing compositions which tend to provide high amount of foam as they tend to associate the amount of foam generated with efficacy of such compositions. For the above reasons surfactants, especially anionic surfactant, is often included in such compositions. We have found that antimicrobial efficacy of carboxylic acids substantially reduced in presence of anionic surfactants.

Thus, on one hand, desired amount of foam is obtained because of presence of surfactant but on the other hand antimicrobial benefit of carboxylic acid gets affected at least partially, which is not preferred.

Hence, there is a need to provide an antimicrobial composition that provides improved antimicrobial effect in presence of anionic surfactant and provides such effect at skin pH (pH 4.5 to 6.5) at relatively short contact time.

It is therefore an object of the present invention to provide an antimicrobial composition.

It is yet another object of the present invention to provide an antimicrobial composition at the pH close to that of human skin.

It is a further object of the present invention to provide an antimicrobial composition with the ability to provide the antimicrobial benefit at relatively short contact time.

It is yet a further object of the present invention to provide an antimicrobial composition comprising carboxylic acids that provides improved antimicrobial effect in presence of anionic surfactant, and at the pH close to that of human skin.

The present inventors have surprisingly found that addition of low amount of a water soluble vinyl polymer comprising polyvinyl alcohol with a carboxylic acid having pKa greater than 4.5 provides synergistic antimicrobial activity in presence of an anionic surfactant, at relatively short contact time, thereby stratifying one or more of the above mentioned object.

SUMMARY OF THE INVENTION

In a first aspect, the invention relates to an antimicrobial composition comprising:a. 0.01 to 10% by weight of a water soluble vinyl polymer comprising polyvinyl alcohol,b. 0.1 to 20% by weight of a carboxylic acid having pKa greater than 4.5; andc. 1 to 80% by weight an anionic surfactant;wherein the pH of the composition is in the range of 4.5 to 6.5.

In a second aspect, the invention relates to a method of cleaning or disinfecting a surface comprising a step of applying on to the said surface a composition of the first aspect.

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 avoidance of doubt, any feature of one aspect of the present invention may be utilized 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.

