EP4436380A1

EP4436380A1 - An antimicrobial composition

Info

Publication number: EP4436380A1
Application number: EP22822009.1A
Authority: EP
Inventors: Shanthi APPAVOO; Anindita HALDER
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Priority date: 2021-11-24
Filing date: 2022-11-23
Publication date: 2024-10-02
Also published as: CN119173142A; WO2023094466A1; AR127750A1

Abstract

The present invention relates to an antimicrobial composition, more particularly a liquid composition that is not harsh on the surfaces being cleaned and disinfected like fabrics, and dishes especially those washed with hand, and also for sanitization of hands and other bodily surfaces. This invention may also be used to develop products that act as multi-utility hygiene liquid compositions that may be used to clean/disinfect any one or more of the above surfaces. This is achieved by combining an amino acid based surfactant having a specific pKa value along with a C3 to C9 alkane diol while the composition has a pH in the range of 2.5 to 4.5.

Description

AN ANTIMICROBIAL COMPOSITION

Field of the Invention

The present invention relates to an antimicrobial composition, more particularly a liquid composition that is not harsh on the surfaces being cleaned and disinfected like fabrics or dishes especially those washed with hand, and also for sanitization of hands and other bodily surfaces. This invention may also be used to develop products that act as multi-utility hygiene liquid compositions that may be used to clean/disinfect any one or more of the above surfaces.

Background of the Invention

Disinfecting cleaning compositions are of great benefit to individuals, since proper use generally may reduce the number of germs and pathogens the individual is exposed to. Such compositions may for instance play an important role in reducing the occurrence and spread of infectious diseases. Disinfecting compositions comprising chlorine-based bleaches are known. Such compositions are sometimes considered to be rather harsh as it may exhibit undesirable side effects, such as corrosion, malodour (like a chlorine smell) and skin irritation or skin-sensitising effects when it comes in contact with a person’s skin or mucous membrane. Further, combination of surfactants like soap and other rather relatively harsh surfactants with other compounds like organic acids have been known to give relatively good anti-antimicrobial activity. However, there are certain circumstances where such cleaning and disinfection need to be achieved when the compositions are applied on the substrates by hand or where the substrate is the hand itself. In such cases the consumers expect the disinfection composition to be mild on the hands, yet deliver high levels of antimicrobial activity. Such substrates include dishes, clothes and other fabric that are especially washed using the hands.

The present inventors during the course of developing various antimicrobial compositions surprisingly found that a combination of an amino acid based surfactant having a specific pKa value and a specific alkane diol in a narrow pH range of 2.5 to 4.5 was able to achieve high antimicrobial activity. This was indeed surprising since neither of the two ingredients are in themselves known for any significant antimicrobial activity. To the knowledge of the present inventors such a combination of actives have not been combined at the claimed conditions and used for delivering high antimicrobial activity.

It is thus an object of the present invention to provide for an antimicrobial composition which is mild on the skin. Summary of the Invention

According to the first aspect of the present invention there is provided an antimicrobial composition comprising

(i) 0.01 to 2 wt% of an amino acid based surfactant having a pKa value in the range of 3 to 5;

(ii) 0.05 to 2 wt% of a C3 to C9 alkane diol;

Wherein the composition has pH in the range of 2.5 to 4.5.

Detailed Description of the Invention

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". Thus, the term "comprising" is meant not to be limiting to any subsequently stated elements, but rather to optionally also encompass nonspecified elements of major or minor functional importance. In other words, the listed steps or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. 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. Except in the 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 "x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "x to y", it is understood that all ranges combining the different endpoints are also contemplated. Unless specified otherwise, amounts as used herein are expressed in percentage by weight based on total weight of the composition and is abbreviated as “wt%”.

Throughout this description, the term disinfection refers to reduction of the number of viable microorganisms in a given medium or on a given surface. Typically, disinfection involves the destruction or inactivation of the microorganisms. Both animate and inanimate media and surfaces are contemplated.

The term " antimicrobial " refers to a compound capable of killing, inhibiting the growth of or controlling the growth of microorganisms at a locus; antimicrobials include bactericides, fungicides and algaecides although the invention is more useful against bacteria. The compositions of the present invention are preferred for non-therapeutic use, and more particularly preferred for use in cleaning surfaces like those on dishes, clothes and other fabric and bodily surfaces like the hands.

The composition comprises an amino acid based surfactant having a pKa value in the range of 3 to 5. They are preferably selected from one or more of sodium lauroyl sarcosinate, sodium oleoyl sarcosinate, sodium oleoyl glutamate, sodium oleoyl glycinate, disodium cocoyl glutamate, sodium cocyl glutamate, disodium lauroyl glutamate, sodium cocoyl glycinate, and sodium lauroyl glycinate. Of these the sarconsinate surfactant is more preferred than a glutamate surfactant which is more preferred than a glycinate surfactant. Thus, the most preferred amino acid surfactant for use in the present invention is selected from one or both of sodium lauroyl sarcosinate and sodium oleoyl sarcosinate.

The amino acid surfactant is included in 0.01 to 2%, preferably 0.02 to 1% by weight of the composition.

The composition of the invention comprises a C3 to C9 alkane diol. Preferred alkanediols are selected from one or more of propanediol, hexanediol and octanediol. The alkane diol is included in 0.05 to 2%, preferably in 0.05 to 1 % by weight of the composition.

Without wishing to be bound by theory the inventors believe that the select alkane diols are found to be good membrane permeabilizers which ensure that the amino acid surfactant can then enter the bacterial cell more easily to damage them thereby boosting the antibacterial performance.

The composition is effective at a pH in the range of 2.5 to 4.5 preferably in the range of 2.5 to 3.5.

The composition preferably includes an organic acid. Preferred organic acid for use in the present invention are one or more of lactic, glycolic, tartatic, and citric acid. The most preferred acid is citric acid. The organic acid may also be present in the salt form. Alkali metal or alkaline earth metal salts are preferred, more preferably alkali metal salts of which sodium salt is most preferred. The composition comprises 0.1 to 5%, preferably 0.5 to 3 wt%, further more preferably 1 to 2.5 wt% of organic acid or salt thereof.

The composition is generally in liquid form. It contains high amount of water. Water is generally present in 80 to 97%, preferably 90 to 94 % by weight of the composition. Liquid laundry detergent composition

The composition may be delivered as a laundry detergent composition which in addition to the essential ingredients of the present invention may also include a surfactant.

The laundry detergent composition in which the present invention may be delivered is preferably in the liquid form. The term liquid may encompass emulsions, suspensions, and compositions having flowable yet stiffer consistency, known as gels or pastes. Pourable liquid detergent compositions preferably have a viscosity of from 200 to 1 ,500 mPa.s, preferably from 200 to 700 mPa.s. Such compositions generally have an aqueous continuous phase. Preferably, the composition comprises at least 50% wt. water and more preferably at least 70% wt. water. Water is generally present in an amount of 20% to 99.9% preferably from 40% to 80% by weight of the composition.

Liquid laundry detergent compositions generally comprise 1 to 30%, preferably from 2 to 15% by weight of one or more surfactants. The surfactant is generally anionic in nature. Amino acid based surfactant, which is an essential feature of the claimed composition, is also an anionic surfactant. However, it is to be understood that, throughout this specification, the use of the term ‘anionic surfactant’ is meant to denote anionic surfactant other than amino acid based surfactant. Preferred anionic surfactants are of the organic sulfates and sulfonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term “alkyl” being used to include the alkyl portion of higher acyl radicals. Examples of such materials include alkyl sulfates, alkyl ether sulfates, alkaryl sulfonates, alpha-olefin sulfonates and mixtures thereof. The alkyl radicals preferably contain from 10 to 18 carbon atoms and may be unsaturated. The alkyl ether sulfates may contain from one to ten ethylene oxide or propylene oxide units per molecule, and preferably contain one to three ethylene oxide units per molecule. The counterion for anionic surfactants is generally an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA). Mixtures of such counterions may also be employed. Sodium and potassium are preferred.

Most preferred surfactants are of the alkylbenzene sulfonates type, particularly linear alkylbenzene sulfonates (LAS) with an alkyl chain length of from 10 to 18 carbon atoms. Some alkyl sulfate surfactant (PAS) may be used, such as non-ethoxylated primary and secondary alkyl sulphates with an alkyl chain length of from 10 to 18. Preferably, the composition comprises from 5 to 20 wt% non-ionic surfactant based on the total weight of composition. A preferred class of nonionic surfactant for use in the invention includes aliphatic Cs to Cis, more preferably C12 to C15 primary linear alcohol ethoxylates with an average of from 3 to 20, more preferably from 5 to 10 moles of ethylene oxide per mole of alcohol. Preferred non-ionic surfactants are the C16/18 alcohol ethoxylates.

Liquid laundry detergent compositions also generally comprise agents like soil release polymers, hydroptropes, co-surfactants, builders, polymeric thickeners, and shading dyes in addition to the above described ingredients. Soil release polymers (SRP) help to improve the detachment of soils from fabric by modifying the fabric surface during washing.

The SRP structure may also include capping groups to control molecular weight or to alter polymer properties such as surface activity. Preferred SRPs for use in the invention include copolyesters formed by condensation of terephthalic acid ester and diol, preferably 1 ,2 propanediol, and further comprising an end cap formed from repeat units of alkylene oxide capped with an alkyl group. The SRP, when included, may range from 0.1 to 10%, desirably from 0.3 to 7%, more preferably from 0.5 to 5% by weight of the composition.

A composition of the invention may incorporate non-aqueous carriers such as hydrotropes, cosolvents and phase stabilizers. Such materials are typically low molecular weight, water-soluble or water-miscible organic liquids such as C1 to C5 monohydric alcohols (such as ethanol and n- or i-propanol); C2 to C6 diols (such as monopropylene glycol and dipropylene glycol); C3 to C9 triols (such as glycerol); polyethylene glycols having a weight average molecular weight (M_w) ranging from about 200 to 600; C1 to C3 alkanolamines such as mono-, di- and triethanolamines; and alkyl aryl sulfonates having up to 3 carbon atoms in the lower alkyl group (such as the sodium and potassium xylene, toluene, ethylbenzene and isopropyl benzene (cumene) sulfonates). Nonaqueous carriers, when included, may be present in an amount ranging from 0.1 to 3%, preferably from 0.5 to 1 % by weight of the composition. The preferred hydrotropes are monopropylene glycol and glycerol.

The liquid laundry detergent composition of the invention may contain one or more cosurfactants (such as amphoteric (zwitterionic) and/or cationic surfactants) in addition to the non-soap anionic and/or nonionic detersive surfactants described above. Such cosurfactant, when included, may be present in an amount ranging from 0.1 to 5% by weight of the composition. The liquid laundry detergent composition may also optionally contain relatively low levels of organic detergent builder or sequestrant material. Examples include the alkali metal citrates, succinates, malonates, carboxymethyl succinates, carboxylates, polycarboxylates aminocarboxylates and polyacetyl carboxylates. If utilized, the organic builder materials may comprise from about 0.5 percent to 20 wt percent, preferably from 1 wt percent to 10 wt percent, of the composition.

When the composition is a liquid laundry detergent composition, it may be diluted with water in ratios in the range of 1 : 5 to 1 :300 e.g. ratios like 1 :50, or 1 :100, 1 :200 to form the wash liquor.

Liquid dishwash composition

The composition of the invention may be useful for upkeep of kitchen items e.g.. utensils and dishes which may be cleaned using a liquid dishwash composition. The various ingredients other than the essential ingredients claimed in the present invention are summarized below. Among the various ingredients, anionic surfactants, non-ionic surfactants, and hydrotropes as detailed under liquid laundry detergent composition may be used in liquid dishwash composition. Additionally, other ingredients which may be included are detailed below:

Preferably, the composition further comprises an amphoteric surfactant. Preferably, an amphoteric surfactants is selected from include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulfobetaines (sultaines), alkyl glycinates, alkyl carboxyglycinates, alkyl amphoacetates, alkyl amphopropionates, alkylamphoglycinates, alkyl amidopropyl hydroxysultaines, acyl taurates and acyl glutamates, having alkyl radicals containing from about 8 to about 22 carbon atoms, the term “alkyl” being used to include the alkyl portion of higher acyl radicals. More preferably, an amphoteric surfactant selected from alkyl amidopropyl betaines, even more preferably cocoamidopropyl betaine. Amphoteric surfactant, when included, may be present in an amount ranging preferably from 0.1 to 5 wt%, more preferably from 0.1 to 4 wt%, even more preferably from 1 to 3 wt%. Mixtures of any of the above described materials may also be used. A good combination of surfactants for use in the present invention in the form of a dishwash composition is one having 1 to 30 wt% anionic surfactant and 0.1 to 5 wt% an amphoteric surfactant.

Liquid dishwash composition may preferably comprise an organic acid or its salts as hereinabove disclosed. It is preferably citric acid or its salt e.g. trisodium citrate. Preferably, the liquid dishwash composition further comprises water in an amount ranging from 5 to 99 wt%, more preferably from 10 to 90 wt%, even more preferably from 15 to 80 wt%, further more preferably from 20 to 70 wt%, still more preferably from 30 to 65 wt%, yet more preferably from 35 to 60 wt%, yet further more preferably from 40 to 55 wt%.

Preferably, the liquid dishwash composition further comprises one or more sequestrants. Preferably, the composition comprises sequestrant may be present in an amount from 0.1 to 5 wt%, more preferably from 0.25 to 4 wt%, even more preferably from 0.5 to 2.5 wt%.

A preferred sequestrant is a phosphonic acid or a salt thereof. The phosphonic acid (or salt thereof) sequestrant is preferably selected from the group consisting of 1 -Hydroxyethylidene-1 ,1 -diphosphonic acid (HEDP; commercially available as Dequest(R) 2010), Diethylenetriaminepenta(methylenephosphonic acid) (DTPMP; commercially available as Dequest(R) 2066), Hexa methylene diamine tetra(methylenephosphonic acid) (HDTMP), Amino tris(methylenephosphonic acid) (ATMP), Ethylene diamine tetra(methylenephosphonic acid) (EDTMP), Tetra methylene diamine tetra(methylenephosphonic acid) (TDTMP); and Phosphono butane tricarboxylic acid (PBTC). The most preferred sequestrant is 1 -Hydroxyethylidene-1 ,1 - diphosphonic acid (HEDP). It is preferable that the sequestrant is added to the formulation in acid form.

Optionally, liquid dishwash composition further comprises an enzyme with or without a suitable enzyme stabilizer. Preferably the composition further comprises an effective amount of at least one enzyme with or without a suitable enzyme stabilizer. Examples of suitable enzymes include pectate lyase, protease, amylase, cellulase, lipase, mannanase; with or without an appropriate stabilizing agent.

Preferably, viscosity of the composition may suitably range from about 200 to about 10,000 mPa.s at 25°C at a shear rate of 21 sec¹. This shear rate is the shear rate that is usually exerted on the liquid when poured from a bottle. Pourable liquid home care compositions generally have a viscosity of from 200 to 1 ,500 mPa.s, preferably from 100 to 800 mPa.s.

The liquid dishwash composition may further comprise one or more polymers. Preferably, polymers can be cationic, anionic, amphoteric or nonionic types with molecular weights higher than 100,000 Dalton. They are known to increase the viscosity and stability of liquid compositions, to enhance in-use and after-use skin sensory feels, and to enhance lather creaminess and lather stability. Examples of polymers include polyvinyl alcohol, polyacrylic acid, silane, siloxane and mixtures thereof. If present, polymers may be present in the composition in an amount ranging preferably from 0.001 to 10 wt%, more preferably from 0.1 to 6 wt%, still further more preferably from 1 to 3 wt%.

Preferably, the composition may be used as is, i.e. neat, or it may be diluted before use. The extent of dilution is generally dependent on market choice. In some markets a more concentrated product is desired while in others a more dilute product is preferred. When the composition is a liquid dishwash compositions it is typically diluted with water in a weight ratio in the range of 1 :1 to 1 :10.

The liquid dishwash composition may optionally comprise ingredients, such as fragrance, colorant, foam boosting agents, and odor absorbing materials.

Multipurpose liquid spray composition

The composition of the invention could be used as a a multipurpose liquid spray composition comprising non-ionic surfactant and 50-90% water. This is usually dispensed from a bottle using a spray pump. Such types of multipurpose liquid spray compositions may be used to clean and disinfect either an inanimate surface or an animate surface. Inanimate surfaces include hard surfaces like floors, walls, windows, doors, furniture, and table tops in various indoor and outdoor locations. Other types of hard surfaces that are cleaned by such compositions include articles found in households, offices and other public places. These products may also be used for sanitizing topical surfaces of the human or animal body. They may be used as bath water, as water used for shaving, cleaning babies between diaper changes, for disinfecting pets and for sanitizing hands at homes, hospitals and in medical clinics; among a host of other personal sanitizing applications.

The multipurpose liquid spray composition may include a stability enhancer which is a non-ionic surfactant. The non-ionic surfactant for use in the present invention is preferably selected from the group comprising fatty alcohol ethoxylates, fatty acid ethoxylates, alkyl phenol ethoxylates or polyoxyethylene sorbitan alkyl esters. The non-ionic surfactant is preferably included in the multipurpose liquid spray composition of the invention at 0.01 to 10%, preferably 0.1 to 5% by weight of the composition. The composition of the invention may be delivered as a sanitizer composition comprising 20 to 50% C2 to C3 alcohol, and 45 to 75% water. Alcohol when at higher than 60 wt% in a composition along with water is one of the most potent antimicrobial compositions. They kill bacteria and virus almost instantly. However, such composition being high in alcohol content are harsh on the skin as it dries up the moisture present on the surface and to some extent below the skin surface. Hence many people prefer hand sanitizers which have low alcohol content. However, alcohol at 20 to 50 wt% in composition does not provide total antimicrobial protection. In such cases, the present invention which comprises amino acid surfactant and alkane diol can supplement the antimicrobial activity of the alcohol to provide total protection. Such hand sanitizers may be carried in small bottle for use in sanitizing the hands when people are travelling and do not have access to soap and water for cleaning hands. Such sanitizers may also be placed at the entrance to buildings like apartments, houses, offices, restaurants and public places like airports, train and bus stations. They are especially useful in hospitals and clinics to minimize the spread of germs through hand contact.

Suitable alcohols for inclusion in the sanitizer compositions of the invention are ethanol, propanol, isopropyl alcohol and combinations thereof. Ethanol is the most preferred alcohol. The composition preferably comprises a combination of ethanol and isopropanol. When ethanol is present, it is preferably included in 25 to 45 wt% of the composition. When isopropanol is present, it is preferably included in 1 to 10 wt%, preferably 1 to 5 wt% of the composition.

The sanitizer composition may optionally comprise a non-ionic surfactant. Non-ionic surfactants as described above for use in multipurpose liquid spray composition may be used in the sanitizer composition.

The sanitizer composition may optionally comprise 0.01 to 1 wt %, preferably 0.05 to 0.8 wt %, more preferably 0.05 to 0.5 wt % of a thickening agent.

The thickening agent in the sanitizer composition according to the invention is preferably selected from homopolymers, copolymers and combinations thereof, wherein said homopolymers and copolymers comprise monomers selected from acrylic acid, acrylates, compounds comprising an acrylate group and combinations thereof. The most preferred thickening agent for use in the sanitizer composition are those of the carbomer class of compounds. In a preferred embodiment the sanitizer composition may comprise 0 to 15 wt. % of optional ingredients such as chelating agents, colorants, perfumes, skin conditioning agents, vitamins like vitamin B3, and combinations thereof. The sanitizer composition preferably comprises skin conditioning agents and these skin conditioning agents are preferably selected from silicones, siloxanes and combinations thereof. The composition preferably comprises vitamins other than vitamin B3 and these vitamins are preferably selected from vitamin A, vitamin E or combinations thereof. Even more preferably the composition comprises vitamin E acetate. The invention shall now be exemplified by the following non-limiting examples.

Examples

Examples A-J, 1-6: Effect of compositions outside the invention as compared to those within the invention on anti-bacterial efficacy:

The following compositions as shown in Table -1 below were prepared.

Table - 1 The above compositions were tested for antibacterial efficacy against the S. aureus and E. hirae using the procedure given below.

European Standard EN1276 (Quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas) was used to measure the log kill.

The data on the bacterial efficacy in terms of log kill at 5 minutes of contact time with the various compositions, is given in table - 2 below:

Table - 2

In the above table, >5 log kill means that starting with 10⁷ bacteria, there is ‘no growth’ of the bacteria observed after treatment with the composition for 5 minutes (indicating an almost total kill of bacteria).

The data in the table - 2 above indicates that the compositions as per the invention (Examples 1 to 6) provide for synergistic anti-microbial kill in 5 minutes of contact time as compared to the kill delivered by the individual components (Examples A to J)

Claims

1. An antimicrobial composition comprising

(ii) 0.05 to 2 wt% of a C3 to C9 alkane diol; wherein the composition has pH in the range of 2.5 to 4.5.

2. A composition as claimed in claim 1 wherein the amino acid surfactant is selected from one or more of sodium lauroyl sarcosinate, sodium oleoyl sarcosinate, sodium oleoyl glutamate, sodium oleoyl glycinate, disodium cocoyl glutamate, sodium cocyl glutamate, disodium lauroyl glutamate, sodium cocoyl glycinate, and sodium lauroyl glycinate..

3. A composition as claimed in claim 1 or 2 wherein the alkane diol is selected from one or more of propanediol, hexanediol or octanediol.

4. A composition as claimed in any one of the preceding claims comprising 0.02 to 1 wt% amino acid based surfactant.

5. A composition as claimed in any one of the preceding claims comprising an organic acid.

6. A composition as claimed in claim 5 wherein the organic acid is selected from one or more of lactic acid, glycolic acid, tartaric acid and citric acid; preferably citric acid.

7. A composition as claimed in claim 5 or 6 wherein the organic acid is included in 0.1 to 5% by weight of the composition.

8. A composition as claimed in any one of the preceding claims 1 to 7 which is a liquid laundry detergent composition additionally comprising 1 to 30 wt% anionic surfactants.

9. A composition as claimed in any one of the preceding claims 1 to 7 which is a liquid dishwash composition additionally comprising 1 to 30 wt% anionic surfactant and 0.1 to 5 wt% an amphoteric surfactant. A composition as claimed in any one of the preceding claims 1 to 7 which is a multipurpose liquid spray composition comprising non-ionic surfactant and 50-90% water. A composition as claimed in any one of the preceding claims 1 to 7 which is a sanitizer composition additionally comprising 20 to 50% C2 to C3 alcohol, and 45 to 75% water.