WO2012146918A1

WO2012146918A1 - Biocidal coating composition

Info

Publication number: WO2012146918A1
Application number: PCT/GB2012/050905
Authority: WO
Inventors: John Toft
Original assignee: Gx Labs Holdings Limited
Priority date: 2011-04-28
Filing date: 2012-04-24
Publication date: 2012-11-01
Also published as: GB201107183D0; WO2012146917A1

Abstract

The present invention relates to a biocidal coating composition which provides long-term residual biocidal activity to a substrate coated therewith, and is in particular wash resistant and abrasion resistant. The biocidal coating composition comprises a biocide and a vinylpyrrolidone-based polymer, where the vinylpyrrolidone-based polymer hold the biocide deep within the surface of the substrate such that the biocide can remain associated with the substrate for prolonged periods of time.

Description

BIOCIDAL COATING COMPOSITION

INTRODUCTION

[0001] The present invention relates to a biocidal coating composition, particularly a hand sanitizer product which exhibits long-term residual biocidal activity. The present invention also relates to a method of preparing the composition, the use of the composition for coating a substrate, its use for providing a substrate with biocidal activity, or its use for providing a substrate with long-term residual biocidal activity.

BACKGROUND OF THE INVENTION

[0002] There is a widespread need to coat certain substrates with biocidal materials in order to kill or prevent the growth of pathogens which could otherwise spread and cause infections. In particular, there is a demand for hand sanitizers to kill and prevent the growth of pathogens on human hands, and in so doing prevent the proliferation of infections between humans.

[0003] At present, a number of hand sanitizer (or hand antiseptic) products are available which provide an alternative or a supplement to washing hands with soap and water. Typically hand sanitizers are formulated as biocidal gels, foams, or liquid solutions, especially hand gels which can be rubbed over the hands. The active biocide in hand sanitizers is most commonly an alcohol (e.g. ethanol, isopropanol, and/or n- propanol). Alcohol hand sanitizer gels provide effective and immediate biocidal action, but due to the rapid evaporation of the alcohol, tend to dry out the hands and exhibit poor residual biocidal action.

[0004] Certain non-alcoholic hand sanitizer products also exist, which typically include small amounts of either benzalkonium chloride, triclosan or povidone-iodine. However, again such products tend to exhibit very limited residual biocidal activity and/or poor adherence to the skin.

[0005] Generally speaking, currently available hand sanitizer products suffer from one or more problems including a lack of residual/long-term biocidal action, poor adherence of the biocide to the skin (especially following washing/cleaning), cracked or damaged coating layers, undue adulteration of the appearance and/or texture of the skin, poor biocidal efficacy, lack of broad spectrum biocidal activity, leaching of the biocide into the environment, lack of biocompatibility, or the use of overly aggressive biocides which further exacerbate the problems associated with biocidal leaching into the environment. [0006] It is an object of the present invention to provide a biocide coating composition, which addresses at least one of the problems of the prior art.

SUMMARY OF THE INVENTION

[0007] In a first aspect of the present invention there is provided a biocidal coating composition, comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units.

[0008] In a second aspect of the present invention there is provided a method of preparing a biocidal coating composition as defined herein, the method comprising mixing a biocide with a polymer which comprises vinylpyrrolidone monomer units.

[0009] In a third aspect of the present invention there is provided a kit of parts for forming the biocidal composition as defined above, the kit comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units.

[0010] In a fourth aspect of the present invention there is provided a method of coating a substrate with a biocidal coating as defined herein, the method comprising applying the biocidal coating composition to the substrate.

[0011] In a fifth aspect of the present invention there is provided a method of providing a substrate with long-term residual biocidal activity by applying the biocidal coating composition as defined herein to the substrate.

[0012] In an sixth aspect of the present invention there is provided a use of the biocidal coating composition or kit of parts as defined above, for coating a substrate, for providing a substrate with biocidal activity, or for providing a substrate with long-term residual biocidal activity.

[0013] In a seventh aspect of the present invention there is provided a biocide-coated substrate obtainable by, obtained by, or directly obtained by the method of coating a substrate as defined herein.

[0014] In an eighth aspect of the present invention, there is provided a biocide-coated substrate, comprising a substrate surface that is coated with a biocidal coating; wherein the biocidal coating comprises a biocide and a polymer which comprises vinylpyrrolidone monomer units.

[0015] In a ninth aspect of the present invention there is provided a biocide-coated substrate (e.g. a hand), comprising a substrate surface that is coated with the biocidal coating composition as defined herein. [0016] In a tenth aspect of the present invention there is provided a use of a vinylpyrrolidone-based polymer to increase the long-term residual biocidal activity of a biocidal coating composition.

[0017] Features, including preferred, suitable, and optional features of any one aspect are also features, including preferred, suitable, and optional features of any other aspect.

[0018] Biocide-coated substrates in accordance with the present invention advantageously exhibit residual/long-term biocidal action. This is due to the enhanced adherence of the biocide to the substrate surface, which is believed to arise from enhanced anchoring of the biocide to the surface via the polymer which comprises vinylpyrrolidone monomer units. Such vinylpyrrolidone-based polymers are believed to form a tight fitting, and durable film over the surface of the substrate so as to retain the biocide in place for longer. It is also thought to help the biocide penetrate and settle within small surface troughs and crevices. The greater stability of the films of the present invention ensures reduced leaching of the biocide into the environment. As such, more aggressive biocides may be used, if desired, but alternatively less aggressive biocides can be used without compromising residual/long-term biocidal action upon the surface.

[0019] Biocidal coatings of the present invention also advantageously avoid undue adulteration of the appearance and/or texture of the surface, because the films formed thereby coalesce and mould to the texture of the existing surface rather than creating a new external surface texture. As such, the textural or light scattering properties of the surface are substantially unaffected.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

[0020] Unless otherwise stated, the following terms used in the specification and claims have the meanings set out below.

[0021] References herein to a "biocidal coating" upon a biocide-coated substrate typically mean a coating substantially free from solvent(s), especially volatile solvent(s), since the biocidal coating is suitably a dried biocidal coating composition upon the substrate. However, a biocidal coating composition described herein suitably comprises a diluent, and may for example be considered to be a diluted form of the biocidal coating. As such, any ingredient or absence thereof described herein in relation to the biocidal coating composition may also be considered applicable to the biocidal coating, and vice versa. Relative quantities of ingredients in each case may also be mutually derivable, simply by including or excluding the diluent as appropriate.

[0022] A "surface of a substrate" or "substrate surface" includes an exterior surface, but also an interior surface where a substrate is suitably porous.

[0023] Herein, a "biocide" is any material, whether chemical or microbial, which can control the effects of pathogens such as bacteria, fungi, viruses, etc, whether through chemical or biological means. A biocide may, in some embodiments, also include one or more preservatives, which are understood to improve residual activity.

[0024] "Biocidal activity" is deemed to be exhibited by a biocide (or biocidal coating) where microbes are observably controlled (observed by techniques well known in the art), be it through their destruction or growth restriction, more so in the presence of the biocide than in its absence. Biocidal activity is suitably defined and measured as a "Log reduction" as defined in Example 5. Bacteriostatic activity is usually defined in terms of a 'zone of inhibition', especially in textile applications.

[0025] Herein, the term "film-forming" is of wide scope and is intended to encompass any substance which facilitates coating of a substrate in a manner of a thin film, including substances which may be termed binding substances and adhesives.

[0026] "Film-forming particles" are small particulates capable of producing a film over a surface of a substrate when appropriately applied thereto.

[0027] "Particle size" is a term well understood in the art, and herein is either the particle diameter (for spherical particles) or the largest distance between two points on the particle (for irregular particles).

[0028] In this specification the term "alkyl" includes both straight and branched chain alkyl groups. References to individual alkyl groups such as "propyl" are specific for the straight chain version only and references to individual branched chain alkyl groups such as "isopropyl" are specific for the branched chain version only. For example, "(1 -6C)alkyl" includes (1 -4C)alkyl, (1 -3C)alkyl, propyl, isopropyl and t-butyl. A similar convention applies to other radicals, for example "phenyl(1 -6C)alkyl" includes phenyl(1 -4C)alkyl, benzyl, 1 -phenylethyl and 2-phenylethyl.

[0029] The term "(m-nC)" or "(m-nC) group" used alone or as a prefix, refers to any group having m to n carbon atoms. Biocidal Coatings and Biocidal Coating Compositions

[0030] The present invention provides a biocidal coating composition, comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units. Such biocidal coating compositions are for coating a substrate with a biocidal coating.

[0031] Polymers comprising vinylpyrrolidone monomer units (or "vinylpyrrolidone-based polymers") can provide excellent films on the surface of substrates to retain the biocide on the surface of the substrate for prolonged periods. This provides prolonged biocidal activity.

[0032] In an embodiment, the biocidal coating composition is a personal care composition, most suitably a hand sanitizer. Hand sanitizers of the invention provide excellent residual biocidal activity, which may even be retained after successive hand washes and/or repeated rubbing of the hands.

[0033] Suitably the weight ratio of the vinylpyrrolidone-based polymer to biocide is from 1000:1 to 1 :1 , suitably from 100:1 to 1 .5:1 , suitably 20:1 to 2:1 . Suitably the amount of biocide is calculated as the sum of all biocides present,

[0034] The biocidal coating composition may comprise a cross-linking agent, for instance, to enable the particles to be cross-linked (e.g. on curing and/or drying). Alternatively, the particles may be self-cross linking, especially when dried as a film and suitably cured.

[0035] The biocidal coating composition may comprise a silane or siloxane, for instance, to enable to biocide and/or vinylpyrrolidone-based polymers to be more effectively bound to the surface of the substrate. The silane or siloxane of the biocidal coating composition may be in polymeric form, particularly where polymerisation of monomers or oligomers is effected on curing and/or dying (e.g. after the composition has been applied as a coating to a substrate). The silane or siloxane may serve to covalently bond to the surface of a substrate to be coated, optionally via organofunctional groups. The silane or siloxane may impart additional biocidal properties to the biocidal coating composition. In a particular embodiment, the biocidal coating comprises a silane or siloxane where the substrate is a textile. However, in certain embodiments, especially where the composition is a personal care composition such as a hand sanitizer, the composition is free of silanes and siloxanes.

[0036] The biocidal coating composition may be (substantially) free of plasticizers, especially when applied to a textile-based substrate. Plasticizers which are suitably excluded may include triacetin, glycerol triacetate, propylene glycol, propylene glycol triacetate, propylene glycol benzoate, diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP).

[0037] The biocidal coating composition typically additionally comprises a diluent, most suitably a diluent which is substantially absent once the biocidal coating composition has dried to form a biocidal coating upon a substrate. The diluent may be any suitable solvent in which the biocide and/or vinylpyrrolidone-based polymers can be dispersed or dissolved. The diluent may suitably be a protic solvent, suitably ethanol, isopropanol, butanol, or water. In a particular embodiment the diluent is water. The diluent is preferably sufficiently volatile to evaporate, preferably at room temperature (25°C) under atmospheric pressure (1 atmosphere), following application of the biocidal coating composition to the surface of a substrate.

[0038] The biocidal coating composition may suitably comprise 0.05% to 15% w/w biocide, suitably 0.1 % to 5% w/w, suitably 0.15% to 1 % w/w.

[0039] The biocidal coating composition may suitably comprise 0.01 % to 10% w/w vinylpyrrolidone-based polymer(s), suitably 0.05% to 5 % w/w, suitably 0.1 % to 3% w/w.

[0040] The biocidal coating composition may suitably comprise 20 to 99.9% w/w diluent, suitably at least 80% w/w, suitably at least 85% w/w, suitably at least 90% w/w.

[0041] In a particular embodiment, the biocidal coating composition comprises:

- 0.05% to 15% w/w of the biocide;

- 0.01 % to 10% w/w of the vinylpyrrolidone-based polymer(s);

- 20 to 99.9% w/w of the diluents.

[0042] The biocidal coating composition may suitably comprise additional ingredients to suit the particular surface intended for coating.

[0043] The biocidal coating composition may additionally comprise a sequestrant. Suitably the sequestrant comprises a chelating agent, for example, EDTA or an acceptable salt thereof (e.g. disodium EDTA). The biocidal coating composition may comprise 0.01 -2% w/w sequestrant, suitably 0.02-0.5% w/w.

[0044] The biocidal coating composition may additionally comprise a phospholipid component, e.g. colalipid C. The biocidal coating composition may comprise 0.1 -5% w/w phospholipid component, suitably 1 -3% w/w.

[0045] In a particular embodiment, the biocidal coating composition further comprises a preservative. Preferably the preservative provides added broad spectrum activity against micro-organisms. The preservative may be part of one of the other ingredients already present. For instance, the preservative may be provided as part of the biocide. Alternatively, the preservative may be provided as a separate ingredient. In a particular embodiment the preservative comprises piroctone olamine (i.e. ethanolamine salt of the hydroxamic acid). The preservative may also comprise 2-phenoxyethanol. In a particular embodiment the preservative comprises both piroctone olamine and 2- phenoxyethanol, suitably commercially available in the form of Nipaguard™ PO-05, though other preservatives may be suitable that do not contain 2-phenoxyethanol. The biocidal coating composition may comprise 0.01 -2% w/w preservative, suitably 0.1 -1 % w/w. Without wishing to be bound by theory, the preservative is thought to improve residual biocidal activity. In some embodiments, the biocidal coating composition comprises one or more such preservatives.

[0046] The biocidal coating composition may additionally comprise a pH adjuster or buffer, for example, lactic acid adjusted to pH 4.0. The pH adjuster may be an acidic pH adjuster. By way of example, a suitable acidic pH adjuster may include an organic acid, e.g. lactic acid, acetic acid, citric acid, etc (especially lactic acid). The acidic pH adjuster suitably has a pK_a in water at 25°C of between 2 and 5. For formulations of different pH, an alkaline pH adjuster may be required, such as sodium hydroxide. In some embodiments, both an acidic and alkaline pH adjuster may be present, either to provide a buffering effect, or to obtain a specifically desired pH. For example, the biocidal coating composition may comprise lactic acid and optionally additional alkaline pH adjuster (e.g. sodium hydroxide) to adjust the pH as desired. The pH of the biocidal coating composition is suitably between 5 and 9. In a particular embodiment, where the biocidal coating composition is a hand sanitizer, the pH adjuster is present in a sufficient quantity to provide a pH of between 5 and 9, more suitably between 6 and 8, most suitably between 6.5 and 7.5. Suitably, the biocidal coating composition comprises sufficient pH adjuster (whether an acidic, alkaline, or acid/alkaline pH adjuster) to obtain the required pH. The biocidal coating composition may comprise 0.01 to 3% w/w pH adjuster, suitably 0.1 to 1 % w/w.

[0047] In one aspect the composition comprises the ingredients of a composition described in the present Examples. In one aspect the composition comprises any of Compositions 2 or 3, as described in the present Examples.

[0048] The biocidal coating composition is suitably a clear/transparent solution or dispersion (i.e. not milky in appearance). [0049] The biocidal coating composition may be in the form of a coating, a dip, a spray, a paint, a dye composition, a cleaning or washing composition, a cosmetic or personal care composition.

[0050] In a particular embodiment, the biocidal coating composition is a personal care composition. The personal care composition is suitably a hand sanitizer. Such compositions are suitably free from silanes or siloxanes.

Vinylpyrrolidone-based Polymer

[0051 ] In a particular embodiment, the vinylpyrrolidone-based polymer is a copolymer comprising vinylpyrrolidone monomer units.

[0052] The vinylpyrrolidone-based polymer is suitably water soluble.

[0053] Suitably, the vinylpyrrolidone-based polymer is a copolymer comprising additional hydrophilic monomer units. For example, the additional monomer units may suitably comprise polar moieties, suitably amine or quaternary amine moieties.

[0054] The vinylpyrrolidone-based polymer suitably forms a film, especially when any associated solvent is removed or evaporates.

[0055] In a particular embodiment, the vinylpyrrolidone-based polymer is a copolymer comprising additional acrylate and/or methacrylate monomer units.

[0056] In an embodiment, the vinylpyrrolidone-based polymer is a terpolymer.

[0057] In an embodiment, the vinylpyrrolidone-based polymer is a copolymer comprising monomer units M₂ and M₃, wherein:

Μ_Ϊ is a vinylpyrrolidone monomer unit;

M₂ is a vinyl monomer comprising a hydrophilic moiety; and

M₃ is a vinyl monomer comprising a hydrophilic moiety.

[0058] The copolymer may be any type of copolymer, including an alternating, periodic, statistical, or block copolymers.

[0059] In an embodiment, the vinylpyrrolidone-based polymer is a copolymer of Formula A:

Formula A wherein:

Μ_Ϊ is a vinylpyrrolidone monomer unit, and x≥1 ;

M₂ is a vinyl monomer comprising a hydrophilic moiety, and y≥0;

M₃ is a vinyl monomer comprising a hydrophilic moiety, and z≥0.

[0060] Suitably, either or both of y and z are≥1 .

[0061] In a particular embodiment, M₂ and M₃ are each independently selected from a monomer unit defined by Formula B:

Formula B

wherein is (1 -5C)alkyl optionally substituted by a hydrophilic moiety (X^; and wherein R₂ is H or (1 -5C)alkyl optionally substituted by a further hydrophilic moiety (Xi).

[0062] In a particular embodiment, Ri is n-butyl, optionally substituted as defined herein.

[0063] In a particular embodiment, R₂ is H.

[0064] Xi is suitably an amine, suitably a tertiary or quaternary amine. Suitably, one of either M₂ or M₃ has Xi as a tertiary amine, whilst the other of M₂ or M₃ has Xi as a quaternary amine.

[0065] In a particular embodiment, one of either M₂ or M₃ has Xi -N(CH₃)₂, and the other of M₂ or M₃ has Xi as -N⁺(CH₃)₂(Ci₂H₂₅).

[0066] In an ambodiment, the vinylpyrrolidone-based polymer is the terpolymer of vinylpyrrolidone (VP), dimethylaminopropyl methacrylamide (DMAPMA) and methacrlyoyaminopropyl lauryldimonium chloride (MAPLDAC) (INCI name: polyquaternium 55), an example of which is the polymeric ingredient of Styleze W20, obtainable from International Specialty Chemicals.

[0067] In a particular embodiment, the vinylpyrrolidone-based polymer is a terpolymer comprising the monomeric components shown below:

[0068] By way of example, the vinylpyrrolidone-based polymer may be Styleze W20 (INCI name: polyquaternium 55), obtainable from International Specialty Chemicals. Typically, "Styleze W" products are supplied a low viscosity aqueous solutions. Herein, references to particular quantities of the vinylpyrrolidone-based polymer(s) suitably refer to the polymer(s) per se (i.e. the undiluted form thereof), except in the Example section where quantities of "Styleze W" products refer to the absolute quantity of these dilute aqueous solutions.

Biocide

[0069] The biocide may be any suitable biocide known in the art, or any biocide which provides biocidal activity as defined hereinabove. The biocide may suitably possess broad spectrum efficacy including against bacteria, fungi and/or viruses. In one aspect the biocide has activity against bacteria, such as Staphylococcus aureus. The biocide may have activity against bacteria, including Pseudomonas aeruginosa, Enterococcus hirae, Escherichia coli, Salmonella, Acinetobacter, Proteus mirabilis etc.

[0070] The biocide may exhibit rapid activity.

[0071] The biocide may suitably retain activity within a pH range of 4-10, suitably 5-9, suitably 6-8.

[0072] The biocide may suitably have low toxicity to humans or animal life. The biocide may suitably be biodegradable.

[0073] Examples of suitable biocides include, but are not limited to, quaternary ammonium compounds (from Lonza), biguanides (Arch Chemicals), guanidines (Lonza), glutaraldehyde (Dow, BASF), formaldehyde (Tennants), iodophors (ISP), chlorines (Ineos), phenol derivatives (Quatchem), amines (Akzo), metal salts, organometallic compounds (Arch Chemicals), Bronopol (BASF) oxidising agents (DuPont), acids (Univar), alkalis (Tennants), etc., and are present in the soluble or insoluble form. The above manufacturers are quoted by way of example. These materials are well known in the art and have been used in formulations of biocidal compositions. Suitably biocides of metallic materials may include metal oxides, metal salts, or organometallic complexes, of which silver, zinc, titanium and copper-based products are commercial the most common. However, metallic biocides have the problem that they are expensive and can cause toxicity problems when they do leach out into the environment. In a particular embodiment, the biocide is an antimicrobial metal-containing compound, such as a metal oxide, suitably a transition metal oxide, most suitably titanium dioxide (Ti0₂).

[0074] As such, water soluble biocides are generally preferred, common examples of which include quaternary ammonium compounds, chlorhexidine gluconate, polyhexamethylene biguanide (PHMB), glutaraldehyde, Bronopol, chlorine compounds, and phenolics. Didecyldimethylammonium chloride (DDAC) is a particularly suitable quaternary ammonium biocide. Being water soluble, such biocides are easily washed away from a substrate surface. The present invention prevents or reduces leaching of such water-soluble biocides, but water soluble biocides comprising cationic moieties are preferred in order to minimise leaching.

[0075] In general, an appropriate biocide is chosen for the substrate or substrate surface of interest. However, in a particular embodiment the biocide is PHMB.

[0076] The biocidal coating composition or coatings derived therefrom may suitably comprise two or more biocides as defined herein. In a particular embodiment, the compositions and coatings comprise a combination of PHMB and DDAC.

[0077] The biocide suitably has an affinity for the vinylpyrrolidone-based polymer(s).

[0078] In a particular embodiment, the biocide is microencapsulated in a polymer matrix. Typically this allows for slow or controlled release of the biocide, as well as increased longevity (i.e. better residual biocide efficacy).

[0079] The biocide may comprise a preservative, suitably which further improves the residual biocidal activity of the biocide and/or biocidal composition.

Silanes and Siloxanes

[0080] As herein described, the biocidal coating or biocidal coating composition may comprise a silane or siloxane. The silane or siloxane suitably retains the biocide and/or polymer film on the surface of a substrate, suitably by chemically and/or physically bonding them to the surface of the substrate, without affecting the inherent properties of that surface. This enhances the durability of the surface coating.

[0081] The silane or siloxane may be either monomeric, oligomeric, or polymeric. In some embodiments, the silane or siloxane is originally monomeric or oligomeric, but subsequently cured upon the substrate to provide a polymeric silane or siloxane.

[0082] The silane or siloxane may be organofunctional silane oligomers. The term "organofunctional silane oligomer" is used herein to refer to silane oligomers that comprise an organofunctional substituent group. Any suitable silane oligomer may be used in the compositions of the present invention.

[0083] The amount of "organofunctional silane oligomer" present in the biocidal coating composition of the invention may vary. Suitably, the amount of organofunctional silane oligomer present is within range of 0.05% to 15% w/w of the total composition, suitably 0.1 to 5% w/w, suitably 1 to 3% w/w. One or more organofunctional silane oligomers may be present in the same composition.

[0084] Organofunctional silane oligomers (e.g. dimers, trimers, tetramers, pentamers etc.) are sufficiently small to penetrate deep into a surface, which can lead to covalent bonding with the surface, as well as self polymerising in situ. Another advantage of these oligomers is that different organofunctional groups can be present within the same silane oligomer molecule; this therefore gives extra versatility to enable the oligomeric silane to be customised for the desired application. For example, these functional groups can be selected or "engineered" to conform to the desired conditions of cure, for example ambient temperature, elevated temperature or UV cure.

[0085] Following application to the surface of a substrate, the compositions form a durable micro or nanofilm of biocide on the coated surface.

[0086] The applicant has found that silane oligomers, (many with functional amino groups), do possess some antimicrobial activity (mainly fungicidal) in their own right.

[0087] In an embodiment of the invention, the biocide is not chemically bonded to the organofunctional silane oligomer. Suitably, the biocide is physically encapsulated within the organofunctional silane oligomer network.

[0088] In an embodiment of the invention, the organofunctional silane oligomer is selected from a silane oligomer, as defined herein, a silsesquioxane, a dipodal silane or mixtures thereof.

[0089] In an embodiment, the silane oligomer comprises 2 to 15 monomer units. [0090] In a further embodiment, the silane oligomer comprises 2 to 10 monomer units.

[0091] In an embodiment, the organofunctional silane oligomer is formed by the condensation of a silane monomer of the formula:

wherein:

Q is a functional group (e.g. halo, hydroxyl, nitro, cyano, carboxy, amino);

M is absent or a linker (e.g. 1 -1 OC alkylene);

at least one of R_{1 ;} R₂ and R₃ is hydroxyl and the others are selected from halo, hydroxyl, 1 -1 OC alkyl, 2-1 OC alkenyl and 2-1 OC alkynyl, M OCalkoxy.

[0092] Suitably, R_{1 ;} R₂ and R₃ are hydroxyl.

[0093] Q may be any suitable functional group known in the art. In the silane oligomers formed by the condensation of the monomers, each Q group may be the same or different.

[0094] M may be any suitable linker group known in the art. Suitably M is alkylene, especially a 1 -5C alkylene.

[0095] In an embodiment, the silane oligomer has the formula:

wherein M and Q are as defined above and n is 1 to 14, more preferably 1 to 9.

[0096] In a further embodiment, the organofunctional silane oligomer is silsesquioxane. Silsesquioxanes are known in the art and possess the empirical formula RSi0_{1 5}, where R is an organofunctional group, such as a group Q or -M-Q defined above. As before, each R group present may be the same or different. Water soluble silsesquioxanes are rich in hydroxyl R groups.

[0097] Silsesquioxanes provide a flexible ceramic backbone with differing organofunctional side groups. New generation hybrid oligomeric silsesquioxanes give better hydrolytic stability, outstanding abrasion performance and yield three dimensional polymer networks. The properties of the final polymer are determined by the molecular make up and reactivity of functional side groups.

[0098] Silsesquioxanes can provide a range of three dimensional forms, including a polyhedral cage structures and ladder structures.

[0099] In a further embodiment, the organofunctional silane is a dipodal silane. Dipodal silanes are known in the art and can improve the bonding and stability of the composition. In addition, by adding these dipodal silane there is further enhancement of the hydrolytic stability of the system. The main advantage of these dipodal silanes is their ability to form six bonds with the substrate as opposed to three.

[00100] A typical structure of dipodal silane is shown below

[00101 ] The R group is a non-hydrolysable organic radical. Any suitable organic radical may be used. Suitably, the organic radical is capable of bonding with organic resins and polymers.

[00102] The X group is hydrolysable (typically alkoxy, acyloxy or chlorine) and enables the silicon group to bond with inorganic substrates.

[00103] Commercial examples of suitable silanes include Dynasylan from Evonik, Vitolane from TWI Cambridge and Dipodal Silanes from Gelest Inc.

[00104] Silanes can also react with insoluble inorganic or organic particulate matter and bind these to substrate surfaces. The organofunctional oligomeric silane has the ability, depending on structure, to interpenetrate the polymer and substrate and bond in a three dimensional network. [00105] In a particular embodiment, where glutaraldehyde is present as a biocide, the silane and/or siloxane are absent. In another embodiment, where glutaraldehyde is present as a biocide, the silane and/or siloxane is present but the silane and/or siloxane is free of amino functional groups (e.g. Q is not amino).

Method of Preparing a Biocidal Coating Composition

[00106] An aspect of the present invention provides a method of preparing the biocidal coating composition described herein, the method comprising mixing a biocide with a vinylpyrrolidone-based polymer(s).

[00107] The biocide may be mixed with the vinylpyrrolidone-based polymer(s) in a diluent as described herein. The biocide and the vinylpyrrolidone-based polymer(s) are suitably mixed to provide a clear/transparent solution or dispersion. The method may further comprise admixing one or more additional ingredients as herein described.

[00108] The biocidal coating composition may be suitably packaged, suitably into a bottle, tin, can, or spray.

Kit of Parts

[00109] In an aspect of the present invention there is provided a kit of parts for forming the biocidal composition as defined above, the kit comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units.

[00110] The kit of parts may suitably comprise the components which, when combined, form the biocidal coating composition described herein. In particular, the kit of parts comprises the biocide and the vinylpyrrolidone-based polymer(s) as separate components or parts. The part comprising the biocide may be a composition, for instance comprising a diluent as described herein. The part comprising the vinylpyrrolidone-based polymer(s) may be a composition, for instance comprising a diluent as described herein. The diluents used in the biocide and the film-forming vinylpyrrolidone-based polymer parts may be the same or different. Either one or both of the parts comprising the biocide or the vinylpyrrolidone-based polymer may comprise additional ingredients of the biocidal coating, as described herein. Alternatively, additional ingredients may form a separate part(s) of the kit.

[00111 ] Typically the kit is suitable for use in the methods described herein, for example, for applying a biocidal coating to a substrate. Coating of a Substrate

[00112] In an aspect of the present invention there is provided a method of coating a substrate with a biocidal coating as defined herein, the method comprising applying the biocidal coating composition to the substrate.

[00113] An aspect of the present invention provides a method of coating a substrate with a biocidal coating, the method comprising, simultaneously or in any sequential order, the steps of i) applying a vinylpyrrolidone-based polymer to a surface of the substrate; ii) applying a biocide to the surface of the substrate; and iii) optionally allowing the surface of the substrate to dry.

[00114] In a particular embodiment, steps i) and ii) are simultaneous in that the biocidal coating composition described herein is applied to the surface of the substrate.

[00115] In another embodiment, step i) is followed by step ii). Suitably the vinylpyrrolidone-based polymer applied in step i) is allowed to dry on to the surface (especially if applied as part of a composition in a suitable diluent) before the biocide is applied as per step i). In such a method, for example, the kit of parts described herein may be employed.

[00116] In another embodiment, step ii) is followed by step i). Suitably the biocide applied in step ii) is allowed to dry on to the surface (especially if applied as part of a composition in a suitable diluent) before the vinylpyrrolidone-based polymer is applied. In such a method, for example, the kit of parts described herein may be employed.

[00117] Regardless of the method used, the biocide may be reapplied, optionally as part of a composition comprising a diluent, at any time, for instance when the biocidal activity is deemed to have diminished below a pre-determined threshold. The vinylpyrrolidone-based polymer remaining in place upon the surface even after the biocidal activity has diminished (perhaps due to depletion of the biocide on the surface) may serve as a platform for receiving and holding further biocide which is later applied. Alternatively extra biocide may be applied shortly after a first application of biocide, suitably with the intention of saturating the surface and/or vinylpyrrolidone-based polymer with the biocide.

[00118] In another embodiment, a second and/or subsequent application of the biocidal coating composition may follow a first application, again with the intention of increasing the biocide content of the surface. [00119] The method may involve a drying step, which may involve heating the surface to be dried, passing a current of air or other gaseous substance over the surface to be dried, air drying, or a combination thereof.

[00120] The method may involve a curing step, which may involve the application of heat and/or electromagnetic radiation (e.g. UV light). The curing step may occur simultaneously with the drying step. The curing step may cause the vinylpyrrolidone- based polymer to form a film, e.g. by coalescing and/or cross-linking.

[00121 ] The method may involve adding additional cross-linking agents which are induced to cross-link when upon the surface. This may further improve biocide retention on the surface. Cross-linking may be induced by heat, electromagnetic radiation (e.g. visible or UV light), the addition of catalysts, or by merely allowing cross-linking to occur on drying or curing.

[00122] Traditionally in textiles the vinylpyrrolidone-based polymer may be applied to the fabric with a suitably resin (e.g. DHDMEU) and a catalyst and cured at 130 - 150 °C for 1 - 5 minutes.

[00123] Another aspect of the present invention provides a method of providing a substrate with long-term residual biocidal activity, the method comprising coating a surface of the substrate (as defined above) with the biocidal coating as defined herein.

Biocide-Coated Substrate

[00124] In an aspect of the present invention there is provided a biocide-coated substrate obtainable by, obtained by, or directly obtained by any one of the methods defined hereinbefore.

[00125] In a further aspect of the present invention, there is provided a biocide- coated substrate, comprising a substrate surface that is coated with a biocidal coating; wherein the biocidal coating comprises a biocide and a polymer which comprises vinylpyrrolidone monomer units.

[00126] In a further aspect of the present invention there is provided a biocide- coated substrate (e.g. a hand), comprising a substrate surface that is coated with the biocidal coating composition as defined herein.

[00127] The biocidal coating suitably does not (substantially) change the appearance of the surface of the substrate. The biocidal coating suitably does not (substantially) change the texture of the surface of the substrate. [00128] Suitably the biocidal coating is flush with the surface of the substrate, i.e. there are substantially no gaps between the biocidal coating and the surface itself.

[00129] The biocidal coating is described further herein, and may for example, be defined as a solvent-free or dried form of a biocidal coating composition as described herein.

[00130] In an embodiment the biocidal coating on the substrate surface comprises a dried biocidal coating composition as described herein, whereby the bulk of any diluent of the biocidal coating composition has been removed or evaporated.

[00131 ] In another embodiment the biocidal coating comprises a combination of a dried composition comprising the vinylpyrrolidone-based polymer and a dried composition comprising the biocide, especially where the vinylpyrrolidone-based polymers and biocide have been separately applied to the surface. This may provide a layered structure to the biocidal coating. However, the biocidal coating may still be defined in terms of a dried biocidal coating composition as described herein.

[00132] The surface of the substrate is suitably covered by a sufficient concentration of the biocidal coating to give rise to biocidal activity. The biocidal coating may suitably comprise greater than or equal to 0.1 μg/mm² of the surface area, suitably greater than or equal to 1 μg/mm², suitably greater than or equal to 10 μg/mm², or suitably greater than or equal to 100 μg/mm². The biocidal coating may suitably comprise less than or equal to 1 mg/mm² of the surface area, suitably less than or equal to 100 μg/mm², or suitably less than or equal to 10 μg/mm².

[00133] In one embodiment, the surface of the substrate comprises a material which is the same as the material comprising the bulk of the substrate itself.

[00134] In another embodiment, the surface of the substrate comprises a material which is different to the material comprising the bulk of the substrate itself.

[00135] The biocidal coating suitably includes the vinylpyrrolidone-based polymer bound to the substrate surface (as a film) and the biocide bound to the vinylpyrrolidone- based polymer. At least some, suitably at least 50%, suitably at least 80%, of the biocide is suitably physically and/or chemically associated with the vinylpyrrolidone-based polymers, suitably forming the polymer film. Suitably the biocide is only physically associated with the vinylpyrrolidone-based polymer.

[00136] Herein, the term "film-forming" is of wide scope and is intended to encompass any substance which facilitates coating of a substrate in a manner of a thin film, including substances which may be termed binding substances and adhesives. Suitably, when included in the biocidal coating upon a surface of a substrate, any film- forming vinylpyrrolidone-based polymers form a thin film layer. In a particular embodiment, the biocidal coating comprises a single coating layer comprising a single film layer. In an alternative embodiment, the biocidal coating comprises a plurality of coating layers each comprising a single film layer. Suitably the biocidal coating comprises a smooth unbroken film upon the substrate.

[00137] The biocidal coating suitably exhibits long-term residual biocidal activity. Herein, "long-term residual biocidal activity" generally means that biodical activity is retained for prolonged periods of time (e.g. suitably from hours to days, the better the cross-linking the more durable will be the polymer film). The biocidal coating may exhibit long-term residual biocidal activity by virtue of the coating's wash resistant and/or abrasive resistance. Wash resistance is generally where a biocidal coating is resistant to being eluted away from the substrate, whereas abrasive resistance is generally where a biocidal coating is resistant to being wiped away or rubbed off the substrate.

[00138] Biocidal activity is suitably retained after washing/cleaning using standard washing/cleaning conditions for the substrate of interest - e.g. for standard cotton textiles this may include a 1 hour wash cycle at 90°C for 50 washes with a known amount of alkaline detergent, whereas cleaning a hard surface may involve abrasive wiping. The biocide-coated substrate may suitably retain 50% of the biocidal activity after a single washing/cleaning using standard washing/cleaning conditions for the substrate of interest, suitably 80% or more, suitably 95% or more, suitably 99% or more. Biocidal activity may be readily measured using routine methods, for example, the methods described in the present Examples. In particular, biocidal activity is suitably a bacteriostatic activity measured as a "Log reduction" as defined in Example 5. The biocide-coated substrate may suitably retain the biocidal activity as described above after washing/cleaning 5 times, suitably after wash/cleaning 10 times, suitably after washing/cleaning 50 times.

[00139] In a particular embodiment, the biocidal coating comprises components which are suitably cross-linked, for instance, to impart greater stability and durability to the biocidal coating upon the surface of the substrate. In a particular embodiment, at least some of the vinylpyrrolidone-based polymer, when coalesced into a film, is cross- linked. Such cross-linking may result from curing or drying the biocidal coating following its initial application to the substrate surface. [00140] The biocide and/or vinylpyrrolidone-based polymer(s) of the biocidal coating may be further bound to the surface of the substrate by virtue of a silane or siloxane as described herein in relation to the biocidal coating.

[00141 ] The substrate may be any suitable substrate for which biocidal protection is sought. The substrate may be a porous or non-porous material.

[00142] The substrate may have either or both of an internal and external surface. An internal surface may comprise the interior of pores. An external surface may be the visible exterior surface around the substrate.

[00143] By way of example, the substrate may include a textile, food preparation surface, wall, ceiling, floor, window, furnishings (soft or hard), work surface, desk, table, human or animal body (e.g. human hand). The substrate may be suitable for use in the home, workplace, hospital or other public environment.

[00144] In a particular embodiment, the substrate is non-textile based, and is suitably free of textile material or fabric material.

[00145] In a particular embodiment, the substrate is a human or animal body or a part thereof. In a particular embodiment, the substrate is a human hand or hands or a part thereof. Where the substrate is a human or animal body, the biocidal coating is suitably free from silanes and/or siloxanes. Where the substrate is a human or animal body, the biocidal coating is suitably a temporary coating, which may deplete on washing and/or over time through abrasion and/or the shedding of skin.

[00146] In another embodiment, the substrate is or comprises a hard surface (e.g. wall, ceiling, floor, window, hard furnishings, work surface, desk, or table). The hard surface may comprise plastics material, ceramic material, glass, metal, or wood. The hard surface is suitably non-porous.

[00147] In a particular embodiment, the substrate is washable or cleanable, suitably by way of immersion, elution, or mere wiping.

[00148] In a particular embodiment, the substrate is a textile-based substrate (e.g. clothing, towels, bed linen, soft furnishings, etc.), suitably a washable textile.

[00149] In a particular embodiment, the biocide-coated substrate is (substantially) free from plasticizers, especially for textile-based substrates. The absence of plasticizers provides surprising improvements for textile-based substrates, especially in terms of the appearance and texture of the coated substrates. Plasticizers can affect the structure of such substrates, especially at high temperatures such as those during a washing cycle, and can render textile-based substrates more susceptible to trapping and retaining dirt and other coloured components which lead to "greying" of the textiles. Instead, for textile-based substrates the biocidal coating described herein may comprise a silane or siloxane. Since the silanes and siloxanes do not affect the structure of the textile itself, but rather the structure of the biocidal coating, the appearance and texture of the textile- based substrates is not compromised.

[00150] The coated substrate may be a paint-coated wall, wherein the paint comprises the biocidal coating and the wall is the substrate.

[00151 ] The surface may be electrostatically unattractive to the biocide. The surface may be non-ionic. The surface may suitably have a zeta potential magnitude (i.e. whether positive or negative) of less than 10mV, suitably less than 5mV. Suitably the surface does not have a negative zeta potential.

[00152] The substrate surface may be an internal and/or external surface. An internal surface is generally present in porous materials. A fibrous material or textile may be considered to have both internal and external surfaces.

[00153] It is typically desirable to coat at least the external surface with the biocidal coating in order to impart long-term residual biocidal activity thereto. In some cases it may be desirable to additionally coat the interstitial and internal surface (e.g. as in the case of textiles).

[00154] The surface may be such that a biocide is easily washed away when employing standard cleaning methods for the substrate of interest. In particular, the surface may lose at least 50% of a "standard biocidal coating" (or at least 50% of the biocidal activity imparted by the "standard biocidal coating" after being first applied to the substrate) when washed or cleaned more 50 times in the standard manner for that substrate, suitably after 10 washes, suitably after 1 wash, wherein the "standard biocidal coating" is a biocidal coating comprising a biocide without the particles of the present invention. For example, a "standard biocidal coating" may comprise the Control Composition described in the present Examples.

[00155] The substrate surface may have aesthetic qualities which are desirably maintained. The surface may have textural qualities which are desirably maintained.

[00156] In a particular embodiment, the surface is a textile surface.

[00157] In another embodiment, the surface is a non-textile surface, and is suitably free of textile or fibrous materials.

[00158] In an embodiment, the surface may include human skin (e.g. on a human hand), and the biocidal coating may be a cosmetic or cosmetically acceptable coating. As such, a biocidal composition may be a cosmetic composition (e.g. personal care composition). In a particular embodiment, the surface is human skin and the biocidal coating composition is a hand sanitizer.

[00159] The surface may comprise plastics material, ceramic material, glass, metal, or wood.

[00160] The surface may be a hard surface, and, for example, may be suitably non-porous.

Applications of Biocidal Coatings and Compositions

[00161 ] An aspect of the present invention provides a use of the biocidal coating, composition thereof, or kit of parts described herein for coating a substrate.

[00162] An aspect of the present invention provides a use of the biocidal coating, composition thereof, or kit of parts described herein for providing a substrate with biocidal activity.

[00163] An aspect of the present invention provides a use of the biocidal coating, composition thereof, or kit of parts described herein for providing a substrate with long- term residual biocidal activity.

[00164] In an embodiment, the substrate is a non-textile based substrate. In such an embodiment, the biocidal coating, composition thereof, or kit of parts may optionally comprise a plasticizer, such as any of those described herein.

[00165] In an embodiment, the substrate is the human body or part thereof, for example a hand or part thereof. In that case, the biocidal coating composition may be a personal care composition, such as a hand-wash or a hand sanitizer.

[00166] In an embodiment, the substrate is or comprises a hard surface, suitably a non-porous hard surface. For use in or on such a substrate, a biocidal coating composition of kit of parts may suitably comprise a silane or siloxane as herein described.

[00167] In an embodiment, the substrate is a textile-based substrate. In such an embodiment, the biocidal coating, biocidal coating composition, or kit of parts is suitably free of plasticizers. In such applications, the biocidal coating composition may be a washing composition or even a dye composition. In another embodiment, the biocidal coating composition may include a fabric softener. [00168] A further aspect of the invention provides a use of a vinylpyrrolidone- based polymer to bind a biocide to a surface of a substrate, comprising, simultaneously or in any sequential order, the steps of i) applying the vinylpyrrolidone-based polymer to the surface of the substrate; ii) applying a biocide to the surface of the substrate; and iii) optionally allowing the surface of the substrate to dry.

Specific Embodiments

[00169] An aspect of the present invention provides a personal care composition comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units. In a particular embodiment, the personal care composition is a hand sanitizer.

[00170] An aspect of the present invention provides a hand sanitizer, comprising:

a biocide;

a vinylpyrrolidone-based polymer;

a sequestrant;

- a preservative

a pH adjuster

a diluent

[00171] An aspect of the present invention provides a hand sanitizer, comprising:

0.1 % to 5% w/w biocide ;

- 0.05% to 3% w/w vinylpyrrolidone-based polymer (e.g. polyquaternium-55, the active ingredient of Styleze W products);

0.01 to 2% w/w sequestrant (e.g. EDTA or a salt thereof);

0.01 -2% w/w preservative (e.g. piroctone olamine and/or 2- phenoxyethanol)

- a pH adjuster (e.g. lactic acid), sufficient to provide a pH between pH 6 and 8

80 to 99.9% w/w a diluent EXAMPLES

Materials

[00172] Polyhexamethylene biguanide (PHMB), which was employed as a biocide, was obtained commercially as Vantocil IB, or Vantocil TG or Cosmocil CQ (20% strength), which is a 20% w/w aqueous solution, all obtainable from Arch Chemicals.

[00173] Alkyldimethylbenzylammonium chloride (ADBAC), which was employed as a biocide, was obtained commercially as, for example Barquat DM50, a 50% strength liquid from Lonza.

[00174] Didecyldimethylammonium chloride (DDAC), which was employed as a biocide, was obtained commercially as a Bardac 22, a 40 or 50% liquid from Lonza.

[00175] Bromonitropropanediol, which was employed as a biocide, was obtained commercially as Bronopol in solid form from BASF.

[00176] Preservatives Nipaguard PO-05 and Nipaguard SMG were commercially available from Clariant.

[00177] The film-forming agents Styleze W20 (PVP derivative), and Styleze W17 were obtained from International Specialty Chemicals. Styleze W products are aqueous solutions of the terpolymer of vinylpyrrolidone (VP), dimethylaminopropyl methacrylamide (DMAPMA) and methacrlyoyaminopropyl lauryldimonium chloride (MAPLDAC) (INCI name: polyquaternium 55.) The chemical structure of the active polymer in Styleze W products is:

C½H¾§ [00178] A silane oligomer Dynasylan 2909 was obtained as a 40% liquid from Evonik.

[00179] Colalipid C, employed as a non-irritant phospholipid, a softener, and mild biocide, was commercially obtained from Colonial Chemicals Inc.

[00180] Ethylenediaminetetraacetic acid (EDTA) and lactic acid were readily commercially available from Chemlink.

Example 1 - Textile (and Control) biocidal compositions

Composition 1

The composition was prepared as a biocide only trial

[00181 ]

- 0.1 % PHMB

- 0.5% ADBAC

- 0.4% DDAC

- 0.1 % Bronopol

- 0.8% Nipaguard PO-05

- 0.2% EDTA

97.9% Deionised Water

[00182] The composition was applied to a surface with a clean dry cloth and allowed to dry. The appearance of the surface was not changed.

[00183] In alternative embodiments, in different applications the ingredients, both active and non active can be replaced added to, or omitted.

Example 2 - Hand sanitizer biocidal compositions

Composition 2

- 0.1 % PHMB

- 0.1 % ADBAC (and/or DDAC)

- 2.0% Colalipid C

- 0.8% Nipaguard PO-05 - 2.0% Styleze W20 (PVP derivative)

- 0.2% EDTA

- 0.5% Lactic acid adjust to pH 4.0 with sodium hydroxide

- 94.3% Deionised Water

[00184] In alternative embodiments, pH can be varied between pH 3.0 - 8.0 using an organic acid and suitable alkali, such as sodium hydroxide.

[00185] In other embodiments, the non-active ingredients may be added to or replaced, for example alcohol (or other suitable solvent) may be substituted all or in part for deionised water.

Application to hands

[00186] Composition 2 was tested by rubbing into a person's hands. The composition was found to be comfortable, and gave no discernable change in appearance or texture of the hands.

[00187] In other embodiments, the hand sanitizer may additionally comprise a fragrance and/ or colour component.

Example 3 - Hand sanitizer biocidal compositions

Composition 3

- 0.5% PHMB (20% aqueous solution)

- 0.25% DDAC (40% aqueous solution)

- 1 .0% Ester ET07 (PEG-7 glyceryl cocoate)

- 0.3% Nipaguard SMG

- 12.0% Styleze W17 diluted 10-fold with water (i.e. a 17% solution of PVP derivative diluted to a 1 .7% aqueous solution of

PVP derivative)

- 0.05% Disodium EDTA

- 1 .0% Jaguar HP105 (obtainable from Rhodia Novecare)

- 0.1 % Fragrance - qs Lactic acid (a quantity sufficient to produce a biocidal

composition of pH 7)

- 83.0% Deionised Water

Application to hands

[00188] Composition 3 was tested by rubbing into a person's hands. The composition was found to be comfortable, and gave no discernable change in appearance or texture of the hands.

Example 4 - Antimicrobial testing

Protocols

[00189] 5 stainless steel samples were tested, which were labelled "control", 1 -2, and 1 W - 2W, the latter being washed versions of duplicate samples 1 -2. The steel samples were 5cm² square swatches of 10mm thickness

[00190] With the exception of the "control", each steel sample was dipped into and completely submerged in a biocidal coating composition (each formulation was marked 1 to 2, the ingredients are listed in the table below) for 10 mins, before removing the samples and allowing them to air dry.

[00191 ] The treated samples were then divided into two lots, and marked 1 to 2 ORIGINAL and 1 to 2 WASHED (designated by a 'W').

[00192] Each of the samples marked WASHED was placed under a fast flowing tap for a period of one minute at an angle of 45 degrees, before being removed, wiped vigorously with a cloth for 30 seconds, and subsequently allowed to air dry. There was no discernable change in appearance or surface texture of the steel samples after treatment with the relevant biocidal coatings.

[00193] The details for each sample are shown in Table 1 below, and correspond to the compositions described hereinbefore. Table 1

[00194] Two replicas of each sample were provided, one replica being tested immediately after initial inoculation, and the other replica being tested after 23 hours post-inoculation incubation. Testing was in accordance with Japanese Industrial Standard J IS Z2801 :2000 to evaluate the antimicrobial activity and efficacy of bacteria on the surface of the steel samples.

[00195] Staphylococcus aureus ATCC 4352 was used as the test bacteria. Bacterial cultures were prepared by inoculating the bacteria onto a nutrient broth and incubating at 37°C for 24 hours. The nutrient broth was then diluted (1 :500) with purified water, and used to dilute the bacterial culture such that the resulting suspension contained approximately 10⁵ bacteria per ml.

[00196] The steel samples were each placed in Petri dishes and inoculated with 0.4mL of a bacterial suspension, taking care to prevent contact of the inoculums with the dish surface and also not allowing the inoculums to spread over off the sample.

[00197] Immediately after inoculation (i.e. at time zero), the first of the replicas for each sample was washed and vigorously massaged with 10ml of SCDLP broth in order to wash out all test bacteria. The number of bacteria recovered from each sample was then determined using a standard serial dilution and pour plate technique. Phosphate buffered physiological saline was used in the serial dilution and plate count agar was used as the medium for growth.

[00198] The remain Petri dishes containing the second replica samples were sealed in desiccators of 99% relative humidity and incubated at 37°C for 23 hours. After incubation, the same SCDLP washing and bacterial number determination was carried out upon these second replica samples as was performed in relation to the first replicas.

[00199] The number of bacteria extracted from the samples was calculated by: (Number of Bacteria) = (Colony Number) x 10 x (Dilution Factor).

[00200] Antimicrobial or bacteriostatic activity was calculated as:

Bacteriostatic activity = log (B/C)

where B = number of bacteria recovered from the control fabric at time 23h;

C = number of bacteria recovered from the test fabrics at time 23h.

Results

[00201 ] The results of the antimicrobial tests are shown in Table 2 below.

Table 2

Conclusions

Composition 1

[00202] This control biocide composition contained no film formers. As expected the original sample gave a good result, but the biocide was removed on subsequent washing and so the result was poor. There was no residual activity.

Composition 2

[00203] This Composition was developed for a particular application, namely as a hand sanitiser, and therefore must possess certain properties - 1 . It must act as an 'invisible glove' to protect hands from pathogens during everyday use

2. It must give a breathable film when dry and not be affected by, or interfere with vapour transmission from the skin.

3. It must be immune from accidental water splashes, but removed by hot soapy water.

4. It must be durable and abrasion resistant when dry to maintain film integrity yet be soft and non detectable on the skin.

5. It must 'lock in' the biocide and hold it in place, aiding the biocide in its performance.

6. It must be biocompatible and a skin non irritant, and as such must be present on the INCI list (International Nomenclature for Cosmetic Ingredients), an internationally recognised body set up to ensure full approval and safety of cosmetic ingredients and personal care products..

7. It must be safe to dispose of in the environment. [00204] All of these criteria are met by Styleze W20 (or other equivalent Styleze products), designed in such a way as to 'lock in' hair colour and prevent loss. In a similar manner it can be use to hold the biocide in place enabling residual biocidal action. It is cationic in nature, further enhancing its binding ability for the biocide.

Claims

CLAIMS:

1 . A biocidal coating composition, comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units (i.e. a vinylpyrrolidone-based polymer).

2. The biocidal coating composition as claimed in claim 1 , wherein the composition is a personal care composition.

3. The biocidal coating composition as claimed in any preceding claim, wherein the composition is a hand sanitizer.

4. The biocidal coating composition as claimed in any preceding claim, wherein the composition comprises 0.05% to 10% w/w vinylpyrrolidone-based polymer(s).

5. The biocidal coating composition as claimed in any preceding claim, wherein the vinylpyrrolidone-based polymer is a copolymer comprising vinylpyrrolidone monomer units.

6. The biocidal coating composition as claimed in any preceding claim, wherein the vinylpyrrolidone-based polymer is a copolymer of Formula A:

Formula A

wherein :

Mi is a vinylpyrrolidone monomer unit, and x≥1 ;

M₂ is a vinyl monomer comprising a hydrophilic moiety, and y≥0;

M₃ is a vinyl monomer comprising a hydrophilic moiety, and z≥0.

7. The biocidal coating composition as claimed in claim 6, wherein both of y and z are≥1 .

8. The biocidal coating composition as claimed in any of claims 6 or 7, wherein M₂ and M₃ are each independently selected from a monomer unit defined by Formula B:

Formula B

wherein is (1 -5C)alkyl optionally substituted by a hydrophilic moiety (X^; and wherein R₂ is H or (1 -5C)alkyl optionally substituted by a further hydrophilic moiety (X^.

9. The biocidal coating composition as claimed in claim 8, wherein is an amine.

10. The biocidal coating composition as claimed in claim 9, wherein is vinylpyrrolidone, M₂ is dimethylaminopropyl methacrylamide, and M₃ is methacrlyoyaminopropyl lauryldimonium chloride.

1 1 . The biocidal coating composition as claimed in any preceding claim, wherein the composition comprises 0.05% to 15% w/w biocide.

12. The biocidal coating composition as claimed in any preceding claim, wherein the biocide is selected from quaternary ammonium compounds, biguanides, guanidines, glutaraldehyde, formaldehyde, iodophors, chlorines, phenol derivatives, amines, metal salts, organometallic compounds, Bronopol, oxidising agents, acids, alkalis, or a combination thereof.

13. The biocidal coating composition as claimed in any preceding claim, wherein the biocide is selected from quaternary ammonium compounds, chlorhexidine gluconate, polyhexamethylene biguanide (PHMB), glutaraldehyde, Bronopol, chlorine compounds, and phenolics, or a combination thereof.

14. The biocidal coating composition as claimed in any preceding claim, wherein the biocide comprises polyhexamethylene biguanide (PHMB).

15. The biocidal coating composition as claimed in any preceding claim, wherein the composition comprises 80 to 99.9% w/w diluent.

16. The biocidal coating composition as claimed in any preceding claim, wherein the pH of the composition is between 5 and 9.

17. The biocidal coating composition as claimed in any preceding claim, wherein the composition is a hand sanitizer, comprising:

0.1 % to 5% w/w biocide;

0.1 % to 5 % w/w vinylpyrrolidone-based polymer (e.g. polyquaternium-55, the active ingredient of Styleze W products);

0.01 to 2% w/w sequestrant (e.g. EDTA or a salt thereof);

0.01 -2% w/w preservative (e.g. piroctone olamine and/or 2- phenoxyethanol)

a pH adjuster (e.g. lactic acid), sufficient to provide a pH between pH 6 and 8

80 to 99.9% w/w a diluent

18. A method of coating a substrate with a biocidal coating, the method comprising, simultaneously or in any sequential order, the steps of i) applying a vinylpyrrolidone- based polymer to a surface of the substrate; ii) applying a biocide to the surface of the substrate; and iii) optionally allowing the surface of the substrate to dry.

19. A biocide-coated substrate, comprising a substrate surface that is coated with a biocidal coating; wherein the biocidal coating comprises a biocide and a polymer which comprises vinylpyrrolidone monomer units.

20. A biocide-coated substrate, comprising a substrate surface that is coated with the biocidal coating composition as defined in any of claims 1 to 17.

21 . The biocide-coated substrate as claimed in any of claims 19 or 20, wherein the substrate is a human hand.

22. A use of a vinylpyrrolidone-based polymer to increase the long-term residual biocidal activity of a biocidal coating composition.

23. A method of providing a substrate with long-term residual biocidal activity by applying the biocidal coating composition as defined in any of claims 1 -17 to the substrate.

24. A kit of parts for forming a biocidal coating, the kit comprising a biocide and a polymer which comprises vinylpyrrolidone monomer units.