Anti-microbial composition and preparation process and use thereof

Abstract

The present invention relates to an anti-microbial composition and preparation process and use thereof. The anti-microbial composition comprises at least one silver compound, at least one organic complexing agent and one or more bases, wherein the organic complexing agent has the structure of Formula (I), wherein R1 is independently hydrogen, a linear or branched C1-C5 alkyl, or an amino group optionally substituted with a C1-C5 alkyl, R2 is independently a linear C1-C5 alkylene, optionally substituted with a C1-C5 alkyl, and R3 is independently hydrogen, a linear or branched C1-C5 alkyl, or a linear or branched C2-C5 alkyl substituted with a carboxyl group. When formulated into an aqueous composition, the composition has good physical stability and even good color stability, particularly against heat and / or light, and pleasant aesthetics for consumers, and it is non-toxic and cost-effective, and particularly can be used in home care compositions, personal care compositions and industrial cleaning compositions.

Description

[0001] Clariant International Ltd 1

[0002] Anti-Microbial Composition and Preparation Process and Use thereof

[0003] Technical Field

[0004] The present invention relates to an anti-microbial composition, in particular, to an antimicrobial composition comprising a silver compound, especially an aqueous antimicrobial composition, and its preparation process and use in home care compositions, personal care compositions and industrial cleaning compositions and other aspects.

[0005] Background Art

[0006] Global demand for anti-microbial compositions is blooming after the novel coronavirus pandemic broken out in 2019.

[0007] The silver-containing compositions have been well known to be broad-spectral antimicrobial agents for versatile applications in both medical and daily care products. However, high content of silver compounds in aqueous form, even for chelation of silver ion, are prone to destabilization when exposed to an alkaline environment, heat, and light, for example, significant discoloration of the solution occurs, e.g., yellowing, reddening, even turning to brownish black, and even brown, gray or black particles are generated, which are susceptible to agglomeration and / or settling. The poor stability not only decreases the anti-microbial efficiency of the aqueous formulation but also brings aesthetically unpleasant feeling to the consumers. Furthermore, most oxides and salts of silver are poorly soluble in water. The anti-microbial efficacy of silver-based anti-microbial agents often tends to gradually diminish over time, especially in the alkaline environment of a cleansing I cleaning composition.

[0008] Karl Wilhelm von Nageli first described the “oligodynamic effect” of silver in 1893 where silver ions and silver-based compounds demonstrate potent anti-microbial properties even at exceptionally low concentrations. Once released into an environment from silver metal or particles, the silver ions interact with microbial organisms like bacteria, viruses, and fungi and disrupt critical molecular structures and processes. This leads to inactivation and death of the microbes. This ability of minute levels of silver ions to exert a microbiocidal effect was originally termed the “oligodynamic effect”, and it has been leveraged for various antimicrobial applications requiring sustained microbial control with minimal concentrations of silver compounds.

[0009] US6939566B2 discloses a microbicidal formulation, comprising at least one disinfectant and a complex of the molecular formula R-M, wherein R is at least one organic chelating moiety, and M is at least one metal ion, and wherein R is present in at least equimolar amount based on the amount of M, and M has a microbicidal effect on at least one microorganism, wherein the at least one organic chelating moiety is an amino acid, wherein the amino acid is selected to form a complex with M at a pH of 2 or less, wherein the amino acid comprises double bonded oxygen, wherein the double bonded oxygen of the amino acid complexes with M at a pH of 2 or less, and wherein the disinfectant and the complex are different, and wherein the complex is a solid in the formulation. The amino acid used is an a-amino acid. The formulation is preferably a concentrate in the form of a gel or a solid. In the examples, soluble silver nitrate and a-amino acid are used to form a complex which is an insoluble precipitate visible to naked eyes, and in the formulation, hydrogen peroxide is additionally used as the disinfectant in combination with the above complex for the preservation of flowers and plants.

[0010] US8637088B2 discloses an antimicrobial composition containing soluble silver dihydrogen citrate as a source of soluble silver ions along with complexing agents and chelating agents that help stabilize the silver ions, allowing maintained antimicrobial efficacy even at neutral or alkaline pH values. The complexing agents used were alkanolamines like monoethanolamine and amino alcohols to prevent silver ion precipitation. Besides, a-amino acids like glutamic acid or chelating agents like EDTA could provide further silver ion stabilization. The disclosed formulations with pH higher than 6 show effective anti-microbial activity. Said document does not relate to long-term storage stability or color stability.

[0011] US10093885B2 or EP3099772B1 discloses an aqueous composition comprising an oligodynamic metal, a chelating agent, an organic acid and less than 1 wt% of free alkali. The stable aqueous anti-microbial composition could use broader source of silver compounds as starting material and show good stability against precipitation, wherein red discoloration is improved. The chelating agent used is selected from ethylene diamine tetraacetic acid (EDTA), ethylene diamine disuccinate (EDDS), N,N-bis(carboxymethyl) glutamic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA) or ethanol diglycinic acid (EDG). Chelating agents are usually used in the form of their salts with a metal. It is found in the document that stability of alkaline aqueous compositions containing an oligodynamic metal could be improved and tendency to discolour could be controlled, by lowering the free alkali content of the composition by the addition of an organic acid. The examples prove that in the case of no addition of an organic fatty acid or a salt thereof, precipitation occurred both before and after 3 months storage. The document does not relate to light stability and improvement of yellow discoloration.

[0012] WO2022184657A1 discloses an aqueous anti-microbial composition comprising silver compounds, amino acids, and fatty acids. The composition shows efficient anti-microbial activity and is stable over a broad pH range. The amino acid specifically listed and preferably used in the document is strongly alkaline a-amino acid, and a fatty acid is needed to stabilize the strongly alkaline a-amino acid. The composition could be incorporated into personal care products and home care products. It is mentioned in the document that the combination of silver compounds with fatty acids and amino acids prevents discoloration of the composition due to UV radiation and / or pH changes and improves the stability. The examples show that the personal care and home care compositions comprising the anti-microbial composition remain stable at room temperature as well as at accelerated stability conditions (temperature of 40 ± 2 °C and humidity of 75 ± 5%) for three months with no change in appearance, and the color results correspond to colorless to yellow specification, but the improvement of yellow discoloration is not further investigated, nor is the lightfastness or sunlight stability of the color specifically investigated.

[0013] Hence, there is a continuing need for anti-microbial compositions that have good stability to meet the aesthetic requirements of consumers on product appearance, in particular, the color, and that are non-toxic and cost-effective to meet the requirements of many applications, especially in personal and home care field. Summary of the Invention

[0014] In view of the problems in the prior art, it is an object of the present invention to provide an anti-microbial composition with good stability, which exhibits good physical stability and even good color stability when formulated into an aqueous composition, wherein said composition does not show agglomeration or precipitation even after long-term storage or even thermal storage, and even exhibits good heat and / or light resistance in terms of color, particularly shows improvement in resistance to yellow discoloration; said composition has pleasant aesthetics for consumers and it is non-toxic and cost-effective, thus meeting the requirements of many applications, especially in the fields of personal and home care and industrial cleaning.

[0015] It is another object of the present invention to provide a process for the preparation of said anti-microbial composition, which is simple, easy to implement, cost-effective and scalable for commercial production.

[0016] It is another object of the present invention to provide use of said anti-microbial composition in personal care compositions, home care compositions, industrial cleaning compositions, coatings or crop applications, preferably as an antimicrobial agent therein.

[0017] Correspondingly, it is also an object of the present invention to provide personal care compositions, home care compositions and industrial cleaning compositions comprising the anti-microbial composition described herein.

[0018] It has been unexpectedly found that the above objects are achieved by preparing a silver compound-based anti-microbial composition having good physical stability and even good color stability against light and / or heat, by using a compound containing one carboxyl group and at least one amino group and having a carbon number of the linking group between the amino group and the carboxyl group of greater than or equal to 2 (i.e., the carbon number of R2 in Formula I of greater than or equal to 1 ) as an organic complexing agent and using a base to adjust the pH value, wherein the organic complexing agent can form a stable complex with the silver compound, which complex can form a stable colloidal dispersion in water.

[0019] Thus, in the first aspect, the present invention provides an anti-microbial composition comprising at least one silver compound, at least one organic complexing agent and one or more bases, wherein the organic complexing agent has the structure of the following Formula I: Formula I in which

[0020] Ri is independently hydrogen, a linear or branched C1-C5 alkyl, or an amino group optionally substituted with a C1-C5 alkyl, and

[0021] R2 is independently a linear C1-C5 alkylene, optionally substituted with a C1-C5 alkyl;

[0022] R3 is independently hydrogen, a linear or branched C1-C5 alkyl, or a linear or branched C2-C5 alkyl substituted with a carboxyl group.

[0023] In another aspect, the present invention provides a process for the preparation of the anti-microbial composition, wherein all the components for the preparation of the composition are mixed.

[0024] In another aspect, the present invention provides use of the anti-microbial composition in personal care compositions, home care compositions, industrial cleaning compositions, coatings or crop applications.

[0025] In yet another aspect, the present invention provides personal care compositions, home care compositions and industrial cleaning compositions comprising the antimicrobial composition.

[0026] Other aspects provided by the present invention will be apparent from the description below. Detailed Description of the Invention

[0027] As used herein, the term "anti-microbial" refers to killing or inhibiting the growth of microorganisms such as bacteria, fungi, or viruses, etc. Anti-microbial compositions or anti-microbial agents can either kill microbes (microbiocidal) or prevent the growth of microbes (microbiostatic).

[0028] The anti-microbial composition of the present invention comprises at least one silver compound, at least one organic complexing agent of Formula I and one or more bases.

[0029] In a preferred embodiment, the anti-microbial composition comprises water and is thus an aqueous anti-microbial composition.

[0030] At room temperature or elevated temperature, the silver compound in the aqueous antimicrobial composition can form a silver complex with the organic complexing agent, said silver complex is insoluble in water, and forms a stable colloidal dispersion in water. The absolute value of the zeta potential of the dispersion can be greater than 20 mV, and the dispersion may comprise nanoparticles of the silver complex having a hydrodynamic diameter of smaller than 500nm, especially smaller than 300 nm, and therefore it is a stable colloidal dispersion.

[0031] Such anti-microbial composition can be stable to light and / or heat at room temperature and elevated temperature for at least 15 days, preferably at least 20 days, in particular at least 60 days, without precipitation or agglomeration, and even can exhibit a relatively low APHA color value, indicating improvement in resistance to yellow discoloration.

[0032] In the anti-microbial composition, the molar ratio of the silver compound to the organic complexing agent can be from 1 :1 .5 to 1 :60, preferably from 1 :6 to 1 : 48.

[0033] In a preferred embodiment, the aqueous anti-microbial composition comprises or consists of the following substances:

[0034] - 0.01 % to 2% by weight, preferably 0.05% to 1 % by weight, particularly preferably 0.05% to 0.5% by weight, of at least one silver compound; - 0.2% to 30% by weight, preferably 0.2% to 10% by weight, more preferably 0.2% to 4% by weight of at least one organic complexing agent, wherein said organic complexing agent has the structure of the following Formula I: in which

[0035] Ri is independently hydrogen, a linear or branched C1-C5 alkyl, or an amino group optionally substituted with a C1-C5 alkyl, and

[0036] R2 is independently a linear C1-C5 alkylene, optionally substituted with a C1-C5 alkyl; preferably, a linear C2-C5 alkylene, optionally substituted with a C1-C5 alkyl;

[0037] R3 is independently hydrogen, a linear or branched C1-C5 alkyl, or a linear or branched C2-C5 alkyl substituted with a carboxyl group;

[0038] - one or more bases in an amount such that the pH value of the composition is adjusted to be between 7 and 12, preferably between 8 and 12, and particularly preferably between 9 and 12; and

[0039] - water.

[0040] In a particularly preferred embodiment, the aqueous anti-microbial composition comprises or consists of the following substances:

[0041] - 0.01 % to 2% by weight, preferably 0.05% to 1 % by weight, particularly preferably 0.05% to 0.5% by weight, of a silver compound, which is selected from silver oxide;

[0042] - 0.2% to 30% by weight, preferably 0.2% to 10% by weight, more preferably 0.2% to 4% by weight of at least one organic complexing agent, which is selected from the group consisting of 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6-aminohexanoic acid, and mixtures thereof;

[0043] - one or more bases selected from the group consisting of sodium hydroxide and potassium hydroxide, in an amount such that the pH value of the composition is adjusted to be between 8 and 12, preferably between 9 and 12; and

[0044] - water. In one embodiment, the composition of the present invention can be a concentrate in gel or solid form, which contains no water or a small amount of water, and can be formulated into an aqueous anti-microbial composition by adding water on site at the time of use.

[0045] Herein, room temperature refers to 25 ± 2 °C.

[0046] Silver compounds

[0047] The anti-microbial composition of the present invention comprises at least one silver compound.

[0048] Suitable silver compounds that may be used include, but are not limited to, silver oxide, silver halides such as silver chloride, silver iodide, silver bromide, and silver fluoride, silver citrate, silver acetate, silver nitrate, silver carbonate, silver sulphate, silver sulphide, silver phosphate, silver benzoate, silver salicylate, and mixtures thereof. In a preferred embodiment, silver oxide is used as the silver compound.

[0049] The silver compound used initially can be in powder form. In the aqueous anti-microbial composition, the silver compound and the organic complexing agent can react to form a stable colloidal dispersion comprising nanoparticles having a hydrodynamic diameter of smaller than 500nm, in particular smaller than 300 nm.

[0050] In the aqueous anti-microbial composition, the content of the silver compound may be 0.01 % to 2% by weight, preferably 0.05% to 1 % by weight, particularly preferably 0.05% to 0.5% by weight, based on the total weight of the aqueous anti-microbial composition.

[0051] Organic complexing agents

[0052] It is essential to the present invention that the anti-microbial composition comprises at least one organic complexing agent of Formula I, in which the carbon number of R2 must be greater than or equal to 1 , i.e. not a single bond, so that the complexing agent is not an a-amino acid but a (3-, y-, 5- or higher amino substituted carboxylic acid.

[0053] In the prior art, instability has been observed in complexes formed by a-amino acids and silver (I) compounds. In the present invention, the alkyl spacer (R2) between the carboxyl group and the amino group contributes to inhibit the generation of precipitates, thereby improving the stability of the composition.

[0054] In addition, in view that a long alkyl may reduce the hydrophilicity of the dispersion of the silver compound, it is preferable that the number of carbon atoms of the main chain of R2 is 5 or less, that is, the number of carbon atoms of the linking group between the carboxyl group and the amino group in Formula I is 6 or less.

[0055] Suitable R2 can be a linear C1-C5 alkylene, optionally substituted with a C1-C5 alkyl. R2 is preferably a linear C2-C5 alkylene optionally substituted with a C1-C5 alkyl. When the number of carbon atoms of the main chain of R2 is 2 or greater, both heat resistance and light resistance can be improved.

[0056] Herein, C1-C5 alkyl encompasses methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n- butyl, isobutyl (2-methylpropyl), sec-butyl (1 -methylpropyl), tert-butyl (1 ,1 - dimethylethyl)), pentyl (n-pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, tertpentyl (1 ,1 -dimethylpropyl), 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, 2-ethylpropyl).

[0057] For example, R2 can be methylene, ethylene, 1 ,3-propylene, 1 ,4-butylene, 1 ,5- pentylene, isopropylene (1 ,2-propylene), 2-methyl-1 ,3-propylene, 2-methyl-1 ,4- butylene, 3-methyl-1 ,4-butylene, 2, 3-dimethyl-1 ,4-butylene, 2-ethyl-1 ,4-butylene, 3- ethyl-1 ,4-butylene, 2-methyl-1 ,5-pentylene, 3-methyl-1 ,5-pentylene, 4-methyl-1 ,5- pentylene, 2-ethyl-1 ,5-pentylene, 3-ethyl-1 ,5-pentylene, or 4-ethyl-1 ,5-pentylene, and the like.

[0058] Preferably, R2 is methylene, ethylene, 1 ,2-propylene, 1 ,3-propylene or 1 ,4-butylene, more preferably ethylene, 1 ,2-propylene, 1 ,3-propylene or 1 ,4-butylene.

[0059] In Formula I, R3 can be independently hydrogen, a linear or branched C1-C5 alkyl, or a linear or branched C2-C5 alkyl substituted with a carboxyl.

[0060] When R3 is a linear or branched C1-C5 alkyl, the organic complexing agent corresponds to an N-alkyl substituted derivative of an amino-substituted carboxylic acid, i.e. , an N-methyl substituted derivative, an N-ethyl substituted derivative, an N- propyl substituted derivative, an N-butyl substituted derivative, an N-pentyl substituted derivative.

[0061] When R3 is a linear or branched C2-C5 alkyl substituted with a carboxyl group, the organic complexing agent corresponds to an N-carboxyalkyl substituted derivative of an amino-substituted carboxylic acid, i.e., an N-carboxyethyl substituted derivative, an N-carboxypropyl substituted derivative, an N-carboxybutyl substituted derivative, an N-carboxypentyl substituted derivative.

[0062] For example, R3 can be hydrogen, methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl (2-methylpropyl), sec-butyl (1 -methylpropyl), tert-butyl (1 ,1 - dimethylethyl)), pentyl (n-pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, tertpentyl (1 ,1 -dimethylpropyl), 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, 2-ethylpropyl), and carboxy-substituted ethyl, propyl, butyl and pentyl, such as carboxyethyl (e.g., 1 -carboxyethyl, 2-carboxyethyl), carboxypropyl (e.g., 1 -carboxypropyl, 2- carboxypropyl, 3-carboxypropyl, 1 -methyl-2-carboxyethyl, etc.), carboxybutyl (e.g., 1 -carboxybutyl, 2-carboxybutyl, 3-carboxybutyl, 4-carboxybutyl, 1 -carboxy-2- methylpropyl, etc.), carboxypentyl (e.g., 1 -carboxypentyl, 2-carboxypentyl, 3- carboxypentyl, 4-carboxypentyl, 5-carboxypentyl, 1 -carboxy-2-methylbutyl, 1 - carboxy-3-methylbutyl, 1 -carboxy-2-ethylpropyl, etc.).

[0063] In a preferred embodiment, R3 is hydrogen. In Formula I, Ri can be independently hydrogen, a linear or branched C1-C5 alkyl, or an amino group optionally substituted with a C1-C5 alkyl.

[0064] For example, R1 can be hydrogen, methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl (2-methylpropyl), sec-butyl (1 -methylpropyl), tert-butyl (1 ,1 - dimethylethyl)), pentyl (n-pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, tertpentyl (1 ,1 -dimethylpropyl), 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, 2-ethylpropyl), amino, methylamino, dimethylamino, ethylamino, or diethylamino, and the like.

[0065] In a preferred embodiment, R1 is hydrogen or methyl.

[0066] Examples of suitable organic complexing agents include, in particular, 3- aminopropionic acid, 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6-aminohexanoic acid and N-alkyl substituted derivatives and N-carboxyalkyl substituted derivatives thereof, including N-methyl substituted derivatives, N-ethyl substituted derivatives, N-propyl substituted derivatives, N-butyl substituted derivatives, N-pentyl substituted derivatives, N-carboxyethyl substituted derivatives, N-carboxypropyl substituted derivatives, N-carboxybutyl substituted derivatives, N- carboxypentyl substituted derivatives, as well as mixtures of these substances; preferably selected from 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, and 6-aminohexanoic acid and N-methyl substituted derivatives and N- carboxyethyl substituted derivatives thereof, as well as mixtures of these substances; further preferably selected from 3-aminobutyric acid and 4-aminobutyric acid and N- methyl substituted derivatives and N-carboxyethyl substituted derivatives thereof, as well as mixtures of these substances.

[0067] The range of the amount used of the organic complexing agent can be calculated from the molar ratio of the silver compound to the complexing agent. In the aqueous anti-microbial composition, the total amount of the organic complexing agent can be from 0.2% to 30% by weight, preferably from 0.2% to 10% by weight, more preferably from 0.2% to 4% by weight, based on the total weight of the aqueous anti-microbial composition. Bases

[0068] The anti-microbial composition comprises one or more bases. The amount thereof may be selected such that the pH value of the composition is adjusted to be between 7 and 12, preferably between 8 and 12. A particularly preferred pH value is between 9 and 12, which is higher than the pKa of the amino group in the organic complexing agent, so that the organic complexing agent can more effectively serve as a ligand to form a stable complex with the silver compound.

[0069] As the base, a commonly used inorganic alkaline compound can be used. Suitable base can be alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide.

[0070] In the aqueous anti-microbial composition, the base is present in free form or forms a salt with the organic complexing agent.

[0071] Preferably, free alkali is present in the aqueous composition. The content of free alkali is preferably less than 0.5% by weight.

[0072] By the free alkali, it is meant that in the aqueous composition, the base is not bonded, complexed or otherwise bound with other substances, for example, it does not form a salt with the organic complexing agent.

[0073] Water and other components

[0074] The anti-microbial composition of the present invention preferably comprises water and is an aqueous dispersion.

[0075] As used herein, water may be demineralized water, deionized water, distilled water, mineral water, or tap water, preferably deionized water.

[0076] The anti-microbial composition may comprise 67.5 to 99.5% by weight, preferably 80 to 99% by weight of water, based on the total weight of the aqueous anti-microbial composition.

[0077] The anti-microbial composition of the present invention may additionally comprise other additives commonly used in an anti-microbial composition.

[0078] For example, the anti-microbial composition may additionally comprise a water-miscible or water-soluble organic solvent, such as lower alkyl alcohols, in particular C1-C5 alkyl monohydric alcohols, such as ethanol or isopropanol. The anti-microbial composition may further comprise a water-soluble polyhydric alcohol. The water-soluble polyhydric alcohol is a polyhydric alcohol having two or more hydroxyl groups in the molecule, and can be selected from the group consisting of: dihydric alcohols; trihydric alcohols; tetrahydric alcohols; pentahydric alcohols; hexahydric alcohols; polymers of polyhydric alcohol; dihydric alcohol alkyl ethers; polyhydric alcohol ether esters; glycerine monoalkyl ethers; sugar alcohols and mixtures thereof.

[0079] Natural solvents can also be used, for example, plant oils, honey, sugar compositions of plant origin, and mixtures thereof.

[0080] The anti-microbial composition may additionally comprise a surfactant. The surfactant may be selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and zwitterionic surfactants. In one embodiment, the anti-microbial composition may be surfactant free.

[0081] The anti-microbial composition may additionally comprise a fatty acid or a salt thereof The fatty acid is for example a saturated or unsaturated, linear or branched Ce to C22 fatty acid. In one embodiment, the anti-microbial composition may be free of fatty acids and salts thereof.

[0082] Process for the preparation of the anti-microbial compositions

[0083] The anti-microbial composition of the present invention can be prepared by a process comprising the step of: mixing all the components used for the preparation of the composition, i.e., mixing at least one silver compound, at least one organic complexing agent, and one or more bases and optionally water and optionally other components.

[0084] For preparing an aqueous composition, the process may be carried out at room temperature or at elevated temperature. For example, after or during mixing, the reaction mixture may be heated, for example to a temperature of up to 70°C, preferably a temperature of 60°C to 70°C. Then the mixture can react to form an aqueous dispersion comprising a silver complex.

[0085] The preparation process may be carried out under normal pressure.

[0086] The aqueous dispersion formed after the reaction may be further filtered to remove insoluble impurities from the starting materials.

[0087] In one embodiment, an organic complexing agent and a base may be first dissolved in water to form a solution, and then a silver compound is added to the solution.

[0088] In a preferred embodiment, the anti-microbial composition of the present invention can be prepared by a process comprising the steps of: a) dissolving an organic complexing agent and a base in a part of water at room temperature or elevated temperature to form a solution; b) adding a silver compound to the solution and stirring them to form a reaction mixture; c) heating the obtained reaction mixture under stirring, for example to a temperature of up to 70°C, preferably 60-70°C, to obtain a dispersion, and optionally maintaining it at this temperature for 20 minutes to 3 hours, preferably 30 minutes to 1 hour; d) while maintaining said heating temperature, continuously adding the remaining amount of water and continuing stirring the reaction mixture, for example, for 1 to 5 hours, preferably for 3 to 5 hours; and e) optionally, filtering the mixture obtained in step d).

[0089] The mixing and reaction process may be carried out in a reaction vessel commonly used in laboratory or in industry, such as a flask, a reaction kettle, a reaction tank, etc.

[0090] The filtration step may be performed using a filter commonly used in laboratory or in industry, such as a Buchner funnel, a glass sand core funnel, a bag filter, or a combination of a microporous filter membrane and a suction funnel.

[0091] The process for the preparation of the anti-microbial composition of the present invention is simple, easy to implement, of low cost and scalable for commercial production.

[0092] Applications

[0093] The anti-microbial compositions of the present invention, when formulated into an aqueous anti-microbial composition, have good physical stability, without agglomeration or precipitation in the composition even after long term storage or thermal storage, and even may simultaneously have good color stability, particularly heat resistance, and even have good heat resistance and light resistance at the same time, and in particular, exhibit improvement in resistance to yellow discoloration, thereby meeting consumer’s aesthetic requirements for product appearance, particularly color. The compositions are non-toxic and cost-effective. Hence, the compositions meet the requirements of many applications, especially in the fields of personal and home care and industrial cleaning.

[0094] Thus, the anti-microbial compositions of the present invention can be used in personal care compositions, home care compositions and industrial cleaning compositions, as well as in coatings and crop applications.

[0095] In one embodiment, the anti-microbial composition may be incorporated into personal care compositions, home care compositions and industrial cleaning compositions to provide anti-microbial effect. Here, the anti-microbial composition of the present invention is used as an anti-microbial agent.

[0096] Correspondingly, the present invention further provides personal care and home care compositions and industrial cleaning compositions comprising an anti-microbial composition according to the present invention.

[0097] The personal care composition may be selected from the group consisting of shampoo, hair and / or skin conditioner, body wash, hand wash, facial cleanser, face mask, bubble bath, intimate wash, bath oil, cleansing milk, micellar water, make-up remover, cleansing wipes, hair mask, perfume, liquid soap, shaving soap, shaving foam, cleansing foam, day cream, anti-ageing cream, body milk, body lotion, body mousse, face serum, eye cream, sunscreen lotion, sun cream, face cream, after-shave lotion, pre-shaving cream, depilatory cream, skin-whitening gel, self-tanning cream, anti-acne gel, mascara, foundation, primer, concealer, blush, bronzer, blemish balm (bb) cream, eyeliner, night cream, eye brow gel, highlighter, lip stain, hand sanitizer, hair oil, nail varnish remover, hair styling gel, hair styling cream, anti-frizz serum, scalp treatment, hair colorant, split end fluid, deodorant, antiperspirant, baby cream, insect repellent, hand cream, sunscreen gel, foot cream, exfoliator, body scrub, cellulite treatment, bar soap, cuticle cream, lip balm, hair treatment, eye shadow, bath additive, body mist, eau de toilette, lubricating gel, moisturizer, serum, toner, aqua sorbet, cream gel, styling mousse, dry shampoo, lip stick, lip gloss, body oil, shower milk, illuminator, lip crayon, hair spray, combing cream, sunblock, ointment, and lipstick, and is preferably a hand wash, body wash, deodorant or antiperspirant.

[0098] The personal care composition may be an emulsion or a gel, preferably an oil-in-water (o / w) emulsion, cream gel or hydrogel.

[0099] The home care composition or industrial cleaning composition may be selected from the group consisting of laundry detergent, fabric softener, multipurpose cleaner, household cleaner, and hard surface cleaner such as floor cleaner, toilet cleaner, bathroom cleaner, and kitchen cleaner, preferably, a dishwashing composition, in particular a hand dishwashing composition, laundry detergent (in the form of a liquid (i.e. , laundry liquid) or in the form of a powder), fabric softener or multipurpose cleaner.

[0100] The multipurpose cleaner or hard surface cleaner may be used, for example, for cleaning ceramic surfaces, stone surfaces, porcelain surfaces, glass surfaces, stainless steel surfaces, metal surfaces, plastic surfaces, linoleum surfaces, and wood surfaces.

[0101] In one embodiment, the multipurpose cleaner or hard surface cleaner remains on the surface after application (“leave-on” application). In another embodiment, the multipurpose cleaner or hard surface cleaner is removed from the surface after application and preferably rinsed off with water (“rinse-off” application).

[0102] The home care composition or industrial cleaning composition may be in the form of a liquid or a gel.

[0103] Preferably, the personal care composition, home care composition or industrial cleaning composition may be selected from the group consisting of laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner, multipurpose cleaner, hand wash, body wash, shampoo, deodorant and antiperspirant.

[0104] The personal care composition, home care composition or industrial cleaning composition may comprise from 0.00005 to 10% by weight, preferably from 0.001 to 10% by weight, more preferably from 0.01 to 5% by weight, particularly preferably from 0.05 to 1 % by weight of the anti-microbial composition, based on the total weight of the personal care composition, home care composition or industrial cleaning composition.

[0105] For example, in a liquid detergent formulation (a laundry liquid formulation), the antimicrobial composition may be used in an amount of up to 5% by weight, preferably from 0.05% to 1 % by weight.

[0106] The amount of the at least one silver compound in the personal care composition, home care composition or industrial cleaning composition may typically be from 1 ppm to 10000 ppm.

[0107] The personal care composition, home care composition or industrial cleaning composition may comprise one or more additional components.

[0108] The additional components may be selected from the group consisting of solvents, acidity regulators, surfactants, colorants, emulsifiers, film formers, fragrances, glossers, humectants, lubricants, moisturizers, pigments, preservatives, skin penetration enhancers, stabilizers, thickeners and viscosity modifiers, oil components, and rheology modifiers (gelling and thickening agents).

[0109] Preferably, the additional components may be selected from the group consisting of solvents (e.g., water, glycols, ethanol, and combinations thereof), acidity regulators (e.g., triethanolamine, trisodium citrate dihydrate, alkali metal hydroxides), and surfactants (e.g., sodium lauryl ether sulfate (SLES), cocamidopropyl betaine, alkylbenzene sulfonic acid, polyethoxylated fatty alcohol).

[0110] In one embodiment, the personal care composition may comprise at least one additive common in the cosmetic, pharmaceutical and dermatological fields. The additive may be selected from the group consisting of surfactants, pH regulators, chelating agents, stabilizers, cationic polymers, buffers, waxes, film formers, superfatting agents, refatting agents, foam stabilizers, active biological substances, preservatives, preservation promoting ingredients, other antifungal substances, antidandruff agents, dyes or pigments, particulate substances, opacifiers, abrasives, absorbents, anti-caking agents, bulking agents, pearlizing agents, direct dyes, perfumes or fragrances, carriers, solvents or diluents, propellants, functional acids, active ingredients, skin-brightening agents, self-tanning agents, exfoliants, enzymes, anti-acne agents, deodorants and antiperspirants, viscosity modifiers, thickeners and gelling agents, antioxidants, astringents, sunscreens, sun protection agents, UV filters, conditioning agents (e.g., hair conditioning or skin conditioning agents), emollients, humectants, occlusive agents, pediculocides, anti-foaming agents, flavouring agents, electrolytes, oxidizing agents and reducing agents.

[0111] In one embodiment, the home care composition or industrial cleaning composition may optionally comprise conventional ingredients commonly used in detergent compositions or cleaning compositions, particularly laundry detergent compositions. Examples of such ingredients include, but are not limited to, builders, bleaching agents, bleach active compounds, bleach activators, bleach catalysts, photobleaches, dye transfer inhibitors, colour protection agents, anti-redeposition agents, dispersing agents, stabilizers, emulsifiers, fabric softening agents, antistatic agents, fluorescent whitening agents, enzymes (e.g., proteases, lipases, amylases, hydrolases, and / or cellulases), enzyme stabilizing agents (e.g., benzamidine hydrochloride, borax, boric acid, boronic acid or salts or esters thereof, peptide aldehydes, polyols, reducing salts, succinic acid), foam regulators, defoamers, malodour reducers, preservatives, disinfectants, hydrotropes (e.g., monopropylene glycol (MPG), glycerol, sodium cumene sulfonate, ethanol, other glycols such as dipropylene glycol, diethers, and urea), fiber lubricants, anti-shrinkage agents, buffers, fragrances, processing aids, colorants, dyes, pigments, anti-corrosion agents, fillers or stabilizers. For detergency boosting, it may be advantageous to use a polymer in a home care cleaning composition or an industrial cleaning composition, especially in a liquid laundry detergent composition. The polymer is preferably a polyethoxylated fatty alcohol, for example, polyethoxylated fatty alcohol (9 EO) and polyethoxylated fatty alcohol (7 EO).

[0112] In a preferred embodiment, the personal care composition, home care composition or industrial cleaning composition may be selected from the group consisting of a laundry detergent (e.g. laundry liquid), hand wash, body wash, and shampoo. In addition to the anti-microbial composition of the present invention, these compositions may further comprise one or more ingredients selected from the group consisting of: solvents, acidity regulators and surfactants, in particular one or more ingredients selected from the group consisting of: water, sodium lauryl ether sulphate (SLES), cocam idopropyl betaine, alkylbenzene sulphonic acid, polyethoxylated fatty alcohol (e.g. polyethoxylated fatty alcohol (9 EO) and polyethoxylated fatty alcohol (7 EO)), triethanolamine, trisodium citrate dihydrate and sodium hydroxide.

[0113] The anti-microbial compositions according to the present invention show improved physical stability and even color stability against heat and / or light when formulated into aqueous compositions, and the personal care, home care, and industrial cleaning compositions prepared from the anti-microbial compositions can show effective anti-microbial effects, which meet or even surpass the requirements on standard products.

[0114] In addition, it is also possible to use at least one silver compound, at least one organic complexing agent and one or more bases in combination, without prior preparation into a composition or formulation into an aqueous composition, but directly in the following applications: personal care compositions, home care compositions, industrial cleaning compositions, coatings or crop applications, preferably laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner, multipurpose cleaner, hand wash, body wash, shampoo, deodorant or antiperspirant. Such use also forms a part of the invention.

[0115] Examples

[0116] The present invention is further illustrated below by means of examples, but it is not limited by these examples.

[0117] 1 . Starting materials

[0118] 2. Preparation of anti-microbial compositions

[0119] First, an organic complexing agent and a base in the weight proportions shown in Table 1 below were added to a reaction vessel at room temperature. An appropriate amount of deionized water was then added and the obtained mixture was stirred until the solutes were completely dissolved. Subsequently, silver oxide in the weight proportion shown in Table 1 was added to the reaction vessel at room temperature and an appropriate amount of deionized water was added. The obtained mixture was heated to 60 °C and maintained under stirring for 30 minutes, until the mixture became clear.

[0120] The remaining amount of deionized water was continuously added to the reaction vessel while maintaining the temperature at 60 °C, and the mixture was continued to be stirred for 3 hours. The resulting dispersion was filtered through a combination of a 0.45 pm microporous filter membrane and a suction funnel to remove the insoluble impurities in the silver oxide, and thereby the final anti-microbial composition was obtained.

[0121] The content of the silver oxide in the obtained anti-microbial composition could be determined by digestion with nitric acid and then titration of the silver ions. Since high purity silver oxide was used in the examples, herein the percent content of silver oxide in the starting material was considered as the percent content of silver oxide in the product.

[0122] Table 1: Chemical composition of the anti-microbial compositions in Examples 1-10

[0123] 3. Performance tests of anti-microbial compositions

[0124] 3.1 APHA color and stability tests

[0125] APHA color, namely the Platinum Cobalt (Pt / Co) scale, is a color standard named for the American Public Health Association (APHA) and defined by ASTM D1209. Sometimes it is also referred to as a “yellowness index” that is used to assess the quality of of clear liquids that are colorless to yellowish. This index is highly relevant to the appearance of a dispersion. As with the increase of yellowness, the shade of the dispersion turns darker and is considered as an unpleasant appearance to consumers.

[0126] APHA color of the anti-microbial composition after 1 month of thermal storage at 50 °C (under away-from-light condition) and sunlight irradiation (normal sunlight, room temperature) was determined for all samples of the examples. APHA color was measured at room temperature using Lovibond PFXi 195 / 1 and using 10 mm cuvette. These results indicate the resistance of the samples to exposure to heat and light.

[0127] Additionally, samples of the anti-microbial compositions of Examples 1 -10 were stored at 50 °C and the duration from the beginning of storage to the first day at which precipitation could be observed by naked eyes was recorded. This duration is indicative of the physical stability of the anti-microbial compositions.

[0128] The results of APHA color and duration of stability test for all samples are shown in Table 2.

[0129] Table 2: Results of duration of stability test and APHA color after 1 month of storage

[0130] *APHA color was only measured for clear dispersion with no precipitate observed.

[0131] NA: Not applicable.

[0132] Table 2 shows that for Example 1 using monosodium glutamate, a composition could also be successfully prepared and the fresh sample was clear and colorless. However, the composition using the a-amino acid showed a low resistance to heat, and precipitation occurred after 14 days of thermal storage.

[0133] In Example 2, the chelating agent N,N-bis(carboxymethyl) glutamic acid mentioned in the prior art was used together with monosodium glutamate. The results showed a further significant decrease in the stability of the composition compared with Example 1 .

[0134] In Example 3, the composition using an organic complexing agent containing an amino group and a carboxyl group linked by an ethylene group (R2 = methylene) showed improved thermal stability, but relatively poor light resistance. Examples 4 and 5 demonstrated the beneficial effects of using organic complexing agents where the carbon number of the main chain of R2 was greater than 1. They improved the physical stability and color stability against both heat and sunlight of the aqueous anti-microbial compositions. Especially for Examples 4 and 5, the samples showed excellent stability resistance to light. The sample of Example 4 had an APHA color of only 13 after 1 month of sunlight irradiation, and its APHA color after 6 months was further determined, which was given by only 49. The sample of Example 5 showed better discoloration resistance effect to light.

[0135] The results of Example 6 showed that with the increase in the carbon number of the organic complexing agent, the stability of the composition decreased for using 8- aminooctanoic acid. Besides, the fresh sample of Example 6 already presented 36 in value of APHA color due to the high carbon number of 8-aminooctanoic acid.

[0136] Examples 9 and 10 showed that the stability of the compositions increased with the increase in the molar ratio of the organic complexing agent to the silver compound.

[0137] The results of Example 7 showed that the hydroxyl side group (i.e., forming amino alcohol structure) resulted in a composition having a much worse stability compared with the complexing agent used in Example 8. The results indicate that amino alcohol had negative effects on the stability of such anti-microbial composition. In contrast, the complexing agent with alkyl side group in Example 8 resulted in a composition exhibiting good resistance against heat and light.

[0138] Such physically stable and even color stable anti-microbial compositions according to the present invention meet the aesthetic requirements of consumers, and further since the complex formed by silver oxide and the organic complexing agent could form a stable colloidal dispersion in water, the concentration of the silver complex can be maintained at a stable level, thereby improving the anti-microbial efficiency of the anti-microbial composition.

[0139] 3.2 Dynamic light scattering and zeta potential Dynamic Light Scattering (DLS) can be used to determine the size distribution profile of small particles in a suspension or dispersion or of polymer molecules in a solution. An important result obtained from the dynamic light scattering results is the intensity weighted average hydrodynamic size, which represents how particles interact with one another in a dispersion based on the electrostatic repulsive layer.

[0140] Zeta potential is an important and readily measurable indicator of the stability of a colloidal dispersion. In general, for a colloidal dispersion system, a high zeta potential is preferred, and such a system has good stability.

[0141] The hydrodynamic diameter of the anti-microbial composition samples (silver complex dispersions) of Examples 1 and 3-5 was determined by Dynamic Light Scattering (DLS) using Malvern Zetasizer Pro, and the results are shown in Table 3 below.

[0142] In addition, the zeta potential of the anti-microbial composition samples of Examples 1 and 3-5 was determined using a nano-size potential analyzer, Malvern Zetasizer Pro, and the results are shown in Table 3 below.

[0143] The results of the examples in Table 3 in combination with the DLVO theory show that the anti-microbial composition samples according to the present invention had a thermal stability of longer than one week in terms of hydrodynamic diameter and zeta potential.

[0144] Table 3: Hydrodynamic diameter and zeta potential of anti-microbial compositions As can be seen from Table 3, the dispersions of all samples had the absolute values of the zeta potentials of larger than 20 mV, and the hydrodynamic diameters of smaller than 300 nm, indicating that they were stable colloidal dispersions. 4. Application tests of anti-microbial compositions

[0145] For application tests, four liquid formulations A, B, C and D, including personal care and home care products, were prepared using the anti-microbial composition of Example 4. Examples C and D were the laundry liquid formulations according to China national standard GB / T13174-2021 laundry liquid standard (“Determination of detergency and cycle of washing property for laundry detergents”). Example E was the reference example not using the anti-microbial composition of the present invention.

[0146] Table 4 lists the detailed formulation of the four samples according to the present invention and the reference sample. The amounts of the anti-microbial composition of Example 4 in the final formulations ranged from 0.5% to 1 % by weight.

[0147] Table 4: Composition of application Examples A-E (wt%)

[0148] *q.s. means suitable amount (quantum sates), herein it means the amount of sodium hydroxide needed to obtain the desired pH value. The liquid laundry detergent needs to be adjusted to a pH value =8.5-9.0 by sodium hydroxide.

[0149] Disinfection test (bacteriostasis test)

[0150] The bacteriostasis test followed the test standard item 7.3 (suspension quantification method) described in China light industry standard QBT2738-2012 (“Test methods for evaluating daily chemical products in antibacterial and bacteriostatic efficacy”). The anti-microbial formulations shown in Table 4 were used for this test. The detailed method was as follows. a. Incubate bacteria and adjust the bacteria concentration to between 1 xi o4cfu / ml and 9x104cfu / ml. b. Dilute the sample at a ratio of 1 : 100 using sterile tap water as the diluent. c. Take 5ml of the sample dilution into a sterile test tube and let it stand for 5 minutes at room temperature. d. Take 0.1 ml of the bacterial solution, add it to the test tube containing 5ml of the sample dilution, quickly mix well and wait for 20 minutes. e. After 20 minutes of action, take 0.5 ml of the mixed solution and add it to a 4.5 ml sterilized PBS test tube and mix well for 10 minutes. f. After 10 minutes, pipette 1 ml of the sample solution into a sterilized petri dish and inoculate two sterilized petri dishes for each sample. Pour 15ml of nutrient agar culture medium, at 40-45 °C, rotate the petri dish to make it evenly distributed, and flip the petri dish after the agar solidifies. g. Place the coated petri dish in a 35 °C incubator for 48 hours of cultivation. h. Record the number of recovered colonies and calculate the bacteriostatic rate.

[0151] The evaluation criteria for the bacteriostasis test were as follows. The bacteriostatic rate R can be calculated as follows: R (%) = (A-B) / Ax100% where

[0152] A stands for the average stain count of the control sample and

[0153] B is the average stain count of the test sample.

[0154] If the bacteriostatic rate is > 90%, the product can be considered as having a bacteriostatic effect; and if the bacteriostatic rate is < 50%, the product is considered as having no bacteriostatic effect.

[0155] Bacteriostasis test was performed on the samples of application Examples A to E, and the results are shown in Table 5 below.

[0156] Table 5: Anti-microbial activity results of the personal care formulations or home care formulations (liquid laundry detergent formulations) of application Examples A-E

[0157] Staphylococcus Escherichia coli /

[0158] Sample name aureus / ATCC 6538 ATCC 8739

[0159] Reduction % Reduction %

[0160] Example A >99.98% 95.53%

[0161] Example B >99.98% 98.44%

[0162] Example C >99.98% 99.62%

[0163] Example D >99.98% 99.76%

[0164] Example E

[0165] (GB Liquid Laundry >99.98% 0

[0166] Detergent)

[0167] As can be seen from Table 5, all samples according to the present invention met the reduction rate of both bacteria types larger than 90% for Staphylococus aureus and Escherichia coli, which could be considered as having effective bacteriostatic effect. As a reference, the GB standard liquid laundry detergent (Example E) without the anti- microbial composition according to the present invention showed no bacteriostatic effect for Escherichia coli.

Claims

Claims:1 . An anti-microbial composition, comprising at least one silver compound, at least one organic complexing agent and one or more bases, wherein the organic complexing agent has the structure of the following Formula I:Formula I in whichRi is independently hydrogen, a linear or branched C1-C5 alkyl, or an amino group optionally substituted with a C1-C5 alkyl,R2 is independently a linear C1-C5 alkylene, optionally substituted with a C1-C5 alkyl, preferably a linear C2-C5 alkylene optionally substituted with a C1-C5 alkyl; and R3 is independently hydrogen, a linear or branched C1-C5 alkyl, or a linear or branched C2-C5 alkyl substituted with a carboxyl group.

2. The anti-microbial composition according to claim 1 , wherein the molar ratio of the silver compound to the organic complexing agent is from 1 :1.5 to 1 :60, preferably from 1 :6 to 1 : 48.

3. The anti-microbial composition according to claim 1 or 2, wherein the silver compound is selected from the group consisting of silver oxide, silver halide, silver citrate, silver acetate, silver nitrate, silver carbonate, silver sulphate, silver sulphide, silver phosphate, silver benzoate, silver salicylate, and mixtures thereof, and is preferably silver oxide.

4. The anti-microbial composition according to any one of claims 1 to 3, wherein R2 in Formula I is independently selected from the group consisting of methylene, ethylene, 1 ,3-propylene, 1 ,4-butylene, 1 ,5-pentylene, isopropylene (1 ,2-propylene), 2-methyl-1 ,3-propylene, 2-methyl-1 ,4-butylene, 3-methyl-1 ,4-butylene, 2,3-dimethyl- 1 ,4-butylene, 2-ethyl-1 ,4-butylene, 3-ethyl-1 ,4-butylene, 2-methyl-1 ,5-pentylene, 3- methyl-1 ,5-pentylene, 4-methyl-1 ,5-pentylene, 2-ethyl-1 ,5-pentylene, 3-ethyl-1 ,5-pentylene and 4-ethyl-1 ,5-pentylene; R2 is preferably selected from methylene, ethylene, 1 ,2-propylene, 1 ,3-propylene and 1 ,4-butylene, and is more preferably selected from ethylene, 1 ,2-propylene, 1 ,3-propylene and 1 ,4-butylene.

5. The anti-microbial composition according to any one of claims 1 to 4, wherein R1 in Formula I is independently selected from the group consisting of hydrogen, methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl, sec-butyl, tert-butyl), pentyl (n-pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, tert-pentyl, 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, 2-ethylpropyl), amino, methylamino, dimethylamino, ethylamino and diethylamino; preferably, R1 is hydrogen or methyl.

6. The anti-microbial composition according to any one of claims 1 to 5, wherein R3 in Formula I is independently selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1 - methylbutyl, 2-methylbutyl, 3-methylbutyl, tert-pentyl, 1 ,2-dimethylpropyl, 2,2- dimethylpropyl, 2-ethylpropyl, and carboxyethyl, carboxypropyl, carboxybutyl and carboxypentyl, and is preferably hydrogen.

7. The anti-microbial composition according to any one of claims 1 to 6, wherein the organic complexing agent is selected from the group consisting of 3-aminopropionic acid, 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6- aminohexanoic acid, and N-methyl substituted derivatives, N-ethyl substituted derivatives, N-propyl substituted derivatives, N-butyl substituted derivatives, N- pentyl substituted derivatives, N-carboxyethyl substituted derivatives, N- carboxypropyl substituted derivatives, N-carboxybutyl substituted derivatives, N- carboxypentyl substituted derivatives thereof, as well as mixtures of these substances, is preferably selected from the group consisting of 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6-aminohexanoic acid, and N-methyl substituted derivatives and N-carboxyethyl substituted derivatives thereof, as well as mixtures of these substances, and is more preferably selected from the group consisting of 3-aminobutyric acid and 4-aminobutyric acid and N-methyl substituted derivatives and N-carboxyethyl substituted derivatives thereof, as well as mixtures of these substances.

8. The anti-microbial composition according to any one of claims 1 to 7, wherein the base is selected from alkali metal hydroxides, and is preferably selected from sodium hydroxide and potassium hydroxide.

9. The anti-microbial composition according to any one of claims 1 to 8, wherein the anti-microbial composition comprises water.

10. The anti-microbial composition according to claim 9, wherein the pH value of the composition is between 7 and 12, preferably between 8 and 12, particularly preferably between 9 and 12.11 . The anti-microbial composition according to claim 9 or 10, wherein the content of the at least one silver compound is 0.01 % to 2% by weight, preferably 0.05% to 1% by weight, particularly preferably 0.05% to 0.5% by weight, based on the total weight of the anti-microbial composition.

12. The anti-microbial composition according to any one of claims 9 to 11 , wherein the anti-microbial composition comprises 0.2% to 30% by weight, preferably 0.2% to 10% by weight, more preferably 0.2% to 4% by weight of the at least one organic complexing agent, based on the total weight of the anti-microbial composition.

13. The anti-microbial composition according to any one of claims 9 to 12, wherein the composition comprises free alkali, wherein the content of free alkali is preferably less than 0.5% by weight.

14. The anti-microbial composition according to any one of claims 9 to 13, wherein the anti-microbial composition comprises a silver complex formed by reacting the silver compound with the organic complexing agent, and in said complex, the organic complexing agent acts as a ligand.

15. The anti-microbial composition according to claim 14, wherein the anti-microbial composition is a colloidal dispersion comprising nanoparticles of the silver complex, andthe nanoparticles have a hydrodynamic diameter of smaller than 500nm, in particular smaller than 300 nm.

16. The anti-microbial composition according to any one of claims 1 to 8, wherein the anti-microbial composition is a gel or a solid.

17. An aqueous anti-microbial composition, wherein the aqueous anti-microbial composition comprises or consists of the following substances:- 0.01 % to 2% by weight, preferably 0.05% to 1 % by weight, particularly preferably 0.05% to 0.5% by weight, of a silver compound, the silver compound being selected from silver oxide;- 0.2% to 30% by weight, preferably 0.2% to 10% by weight, more preferably 0.2% to 4% by weight of at least one organic complexing agent, the organic complexing agent being selected from the group consisting of 3-aminobutyric acid, 4-aminobutyric acid, 5-aminopentanoic acid, 6-aminohexanoic acid, and mixtures thereof;- one or more bases selected from sodium hydroxide and potassium hydroxide, in an amount such that the pH value of the composition is adjusted to be between 8 and 12, preferably between 9 and 12; and- water.

18. A process for the preparation of an anti-microbial composition according to any one of claims 1 -17, comprising the step of: mixing all the components used for the preparation of the composition.

19. The process according to claim 18, wherein the process is carried out at room temperature or at elevated temperature, for example, by heating to a temperature of up to 70°C, and the mixture reacts to form an aqueous dispersion comprising a silver complex.

20. The process according to claim 18 or 19, wherein an organic complexing agent and a base are first dissolved in water to form a solution, and then a silver compound is added to the solution.

21. Use of the anti-microbial composition according to any one of claims 1 -17 in personal care compositions, home care compositions, industrial cleaning compositions, coatings or crop applications, preferably in a laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner, multipurpose cleaner, hand wash, body wash, shampoo, deodorant or antiperspirant.

22. A home care composition, comprising the anti-microbial composition according to any one of claims 1 -17, preferably in an amount from 0.00005 to 10% by weight, preferably from 0.001 to 10% by weight, more preferably from 0.01 to 5% by weight, particularly preferably from 0.05 to 1 % by weight, based on the total weight of the home care composition; wherein the home care composition is preferably selected from the group consisting of a laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner and multipurpose cleaner.

23. A personal care composition or industrial cleaning composition, comprising the antimicrobial composition according to any one of claims 1 -17, preferably in an amount from 0.00005 to 10% by weight, preferably from 0.001 to 10% by weight, more preferably from 0.01 to 5% by weight, particularly preferably from 0.05 to 1 % by weight, based on the total weight of the personal care composition or industrial cleaning composition; wherein the personal care composition or industrial cleaning composition is preferably selected from the group consisting of a laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner, multipurpose cleaner, hand wash, body wash, shampoo, deodorant and antiperspirant.

24. Use of a combination of the at least one silver compound, at least one organic complexing agent and one or more bases as defined in any one of claims 1 to 8 in the following: home care compositions, personal care compositions, industrial cleaning compositions, coatings or crop applications, preferably a laundry detergent, fabric softener, hard surface cleaner, dishwashing detergent, kitchen utensil cleaner, multipurpose cleaner, hand wash, body wash, shampoo, deodorant or antiperspirant.

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