WO2012146917A1

WO2012146917A1 - Biocide-coated substrate

Info

Publication number: WO2012146917A1
Application number: PCT/GB2012/050904
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; WO2012146918A1

Abstract

The present invention relates to a substrate coated with biocidal coating which provides long-term residual biocidal activity, and is in particular wash resistant and abrasion resistant. The biocidal coating comprises a biocide and particles having a particle size of less than or equal to 1µm. Such particles carry and 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

BIOCIDE-COATED SUBSTRATE

INTRODUCTION

[0001] The present invention relates to a biocide-coated substrate, particularly a substrate exhibiting long-term residual biocidal activity. The present invention also relates to a biocidal coating composition, a method of preparing the composition, and the use of the composition for coating a substrate, or providing a substrate with biocidal activity, or providing a substrate with long-term residual biocidal activity. The invention further relates to a method of coating a substrate, a method of providing a substrate with long-term residual biocidal activity, and the use of particles to bind a biocide to a surface of a substrate, together with a kit of parts for use in the methods of the invention.

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.

[0003] At present, a number of biocidal coatings are available, for example 'Surfacine™' or 'Aegis™' which, when applied to a surface, provide biocidal protection to that surface for a time. However, a surface coated with one of these coatings will often suffer from, for example, a lack of residual/long-term biocidal action, poor adherence of the biocide to the surface (especially following washing/cleaning), cracked or damaged coating layers, undue adulteration of the appearance and/or texture of the surface, poor biocidal efficacy, lack of broad spectrum biocidal activity, leaching of the biocide into the environment (e.g. via washing machine waste effluent in the case of biocidal-coated textiles), lack of biocompatibility, or the use of overly aggressive biocides which further exacerbate the problems associated with biocidal leaching into the environment.

[0004] It is an object of the present invention to provide a biocide coating composition and a biocide-coated substrate, which addresses at least one of the problems of the prior art.

SUMMARY OF THE INVENTION

[0005] In a first 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 particles, the particles having a particle size of less than or equal to 1 μηι.

[0006] In a second aspect of the present invention there is provided a biocidal coating composition, comprising a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

[0007] In a third aspect of the present invention there is provided a kit of parts, comprising a biocide and particles, the particles having a particle size of less than or equal to 1 μηι

[0008] In a fourth aspect of the present invention there is provided a method of preparing a biocidal coating composition as described herein, the method comprising mixing a biocide with particles, the particles having a particle size of less than or equal to 1 μηι.

[0009] In a fifth aspect of the present invention there is provided a method of coating a substrate with a biocidal coating, the method comprising, simultaneously or in any sequential order, the steps of i) applying particles 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; wherein the particles have a particle size of less than or equal to 1 μηι.

[0010] In a sixth aspect of the present invention there is provided a method of providing a substrate with long-term residual biocidal activity, the method comprising coating a surface of the substrate with the biocidal coating of the first aspect.

[0011] In a seventh aspect of the present invention there is provided a use of the biocidal coating of the first aspect, composition thereof of the second aspect, or kit of parts of the third aspect for coating a substrate, for providing a substrate with biocidal activity, or for providing a substrate with long-term residual biocidal activity.

[0012] In a eighth aspect of the present invention there is provided a use of particles to bind a biocide to a surface of a substrate, comprising, simultaneously or in any sequential order, the steps of i) applying the particles 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; wherein the particles have a particle of less than or equal to 1 μηι.

[0013] Features, including preferred, suitable, and optional features of any one aspect are also features, including preferred, suitable, and optional features of any other aspect.

[0014] 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 small particles. The small particles, which may themselves have enhanced affinity for the biocide by virtue of their large collective surface area or through other attractive means, are thought to form an improved, tight fitting, and durable film over the surface through being able to penetrate and settle in small surface troughs and crevices which would be otherwise impenetrable to larger particles. Other films generally fail to penetrate such small troughs and crevices and thereby leave film-surface gaps which render the film less stable and more susceptible to cracks or damage. 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.

[0015] Biocidal coatings of the present invention also advantageously avoid undue adulteration of the appearance and/or texture of the surface, because the particles 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.

BRIEF DESCRIPTION OF THE DRA WINGS

[0016] To help explain the present invention, and how embodiments of the same may be put into effect, reference is now made, by way of example, to the following figures, in which:

[0017] Figure 1 is a microscopic photographic image of a polyacrylate-coated fibre; and

[0018] Figure 2 is a microscopic photographic image of a polyurethane-coated fibre.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

[0019] Unless otherwise stated, the following terms used in the specification and claims have the meanings set out below.

[0020] A "surface of a substrate" or "substrate surface" includes an exterior surface, but also an interior surface where a substrate is suitably porous. [0021] 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.

[0022] "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.

[0023] 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.

[0024] "Film-forming particles" are small particulates capable of producing a film over a surface of a substrate when appropriately applied thereto.

[0025] "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).

[0026] 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.

[0027] The term "(m-nC)" or "(m-nC) group" used alone or as a prefix, refers to any group having m to n carbon atoms.

Biocide-Coated Substrate

[0028] One aspect of the present invention provides a biocide-coated substrate, comprising a substrate surface that is coated with a biocidal coating; wherein the biocidal coating comprises a biocide and particles, the particles having a particle size less than or equal to 1 μηι. [0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] In another embodiment the biocidal coating comprises a combination of a dried composition comprising the particles and a dried composition comprising the biocide, especially where the particles 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.

[0034] 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.

[0035] 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.

[0036] In another embodiment, the surface of the substrate comprises a material which is different to the material comprising the bulk of the substrate itself.

[0037] The biocidal coating suitably includes the particles bound to the substrate surface (as a film) and the biocide bound to the particles. At least some, suitably at least 50%, suitably at least 80%, of the biocide is suitably physically and/or chemically associated with the particles, suitably forming the polymer film. Suitably the biocide is only physically associated with the particles. [0038] 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.

[0039] 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.

[0040] 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 particles, when coalesced into a film, are cross-linked. Such cross-linking may result from curing or drying the biocidal coating following its initial application to the substrate surface.

[0041] The biocide and/or particles 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.

[0042] The substrate may be any suitable substrate for which biocidal protection is sought. The substrate may be a porous or non-porous material.

[0043] 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. [0044] 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.

[0045] In a particular embodiment, the substrate is non-textile based, and is suitably free of textile material or fabric material.

[0046] 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 the shedding of skin.

[0047] 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.

[0048] In a particular embodiment, the substrate is washable or cleanable, suitably by way of immersion, elution, or mere wiping.

[0049] In a particular embodiment, the substrate is a textile-based substrate (e.g. clothing, towels, bed linen, soft furnishings, etc.), suitably a washable textile.

[0050] 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.

[0051] The coated substrate may be a paint-coated wall, wherein the paint comprises the biocidal coating and the wall is the substrate. [0052] 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.

[0053] 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.

[0054] 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).

[0055] 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.

[0056] The substrate surface may have aesthetic qualities which are desirably maintained. The surface may have textural qualities which are desirably maintained.

[0057] In a particular embodiment, the surface is a textile surface.

[0058] In another embodiment, the surface is a non-textile surface, and is suitably free of textile or fibrous materials.

[0059] The surface may comprise plastics material, ceramic material, glass, metal, or wood. 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).

[0060] The surface may be a hard surface, and, for example, may be suitably non- porous. Biocidal Coatings and Biocidal Coating Compositions

[0061] The biocidal coating described herein is typically substantially free from solvent(s), especially volatile solvent(s), since the biocidal coating is suitably dry 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 may also be considered applicable to the biocidal coating composition, and vice versa. Relative quantities of ingredients in each case may also be mutually derivable, simply by including or excluding the diluent as appropriate.

[0062] The biocidal coating comprise a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

[0063] Suitably the weight ratio of particles to biocide in the biocidal coating upon the surface of the substrate is from 10000:1 to 1 :1 , suitably from 1000:1 to 10:1 , suitably 200:1 to 50:1 . Suitably the amount of biocide is calculated as the sum of all biocides present.

[0064] The biocidal coating 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.

[0065] The biocidal coating may comprise a silane or siloxane, for instance, to enable to biocide and/or particles to be more effectively bound to the surface of the substrate. The silane or siloxane of the biocidal coating may be in polymeric form, particularly where polymerisation of monomers or oligomers is effected on curing and/or dying. The silane or siloxane may be covalently bonded to the substrate of the surface, optionally via organofunctional groups. The silane or siloxane may impart additional biocidal properties to the biocidal coating. In a particular embodiment, the biocidal coating comprises a silane or siloxane where the substrate is a textile.

[0066] The biocidal coating 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).

[0067] An aspect of the present invention provides a biocidal coating composition, comprising a biocide and particles, the particles having a particle size less than or equal to 1 μιτι. [0068] The biocidal coating composition may comprise the components of a biocidal coating, and additionally comprise a diluent. The diluent may be any suitable solvent in which the particles can be dispersed or suspended, preferably dispersed. The diluent may be any suitable solvent in which the biocide can be dissolved, dispersed or suspended, preferably dissolved. The diluent may suitably be an aprotic 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.

[0069] The biocidal coating composition may suitably comprise 0.05% to 15% w/w biocide, suitably 0.1 % to 5% w/w, suitably 0.2% to 2% w/w.

[0070] The biocidal coating composition may suitably comprise 0.05% to 15% w/w particles, suitably 0.1 % to10 % w/w, suitably 0.5% to 5% w/w.

[0071 ] The biocidal coating composition may suitably comprise 20 to 99.9% w/w diluents.

[0072] The biocidal coating composition may suitably comprise additional ingredients as per the biocidal coating. For instance, the biocidal coating composition may additionally comprise a preservative. 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 an embodiment, the preservative comprises at least 0.01 wt% of the biocidal coating composition, suitably at least 0.05 wt%. In an embodiment, the preservative comprises at most 2 wt% of the biocidal coating composition, suitably at most 1 wt%. 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.

[0073] In a particular embodiment, the biocidal coating composition comprises:

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

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

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

[0074] The biocidal coating composition may additionally comprise a sequestrant. Suitably the sequestrant comprises a chelating, for example, EDTA. [0075] 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 adjust 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.

[0076] 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 3 or 4, as described in the present Examples.

[0077] The biocidal coating composition is suitably a clear/transparent dispersion (i.e. not milky in appearance).

[0078] 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.

[0079] In a particular embodiment, the biocidal coating composition is a personal care composition. The personal care composition is suitably a hand-wash. Such compositions are suitably free from silanes or siloxanes.

[0080] An aspect of the present invention provides a method of preparing the biocidal coating composition described herein, the method comprising mixing a biocide with particles, the particles having a particle size less than or equal to 1 μηι.

[0081] The biocide may be mixed with the particles in a diluent as described herein. The biocide and the particles are suitably mixed to provide a clear/transparent dispersion. The method may further comprise admixing one or more additional ingredient as herein described.

[0082] The particles may suitably be formed by micronizing particles having a particle size greater than 1 μηι.

[0083] The biocidal coating composition may be suitably packaged, suitably into a bottle, tin, can, or spray. Biocide

[0084] 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.

[0085] The biocide may exhibit rapid activity.

[0086] The biocide may suitably retain activity within a pH range of 4-10, suitably 5-9, suitably 6-8.

[0087] The biocide may suitably have low toxicity to humans or animal life. The biocide may suitably be biodegradable.

[0088] 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.

[0089] 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).

[0090] 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. 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. [0091] In general, an appropriate biocide is chosen for the substrate or substrate surface of interest. However, in a particular embodiment the biocide is PHMB.

[0092] The biocide suitably has an affinity for the particles, for example, for the surface of the particles. In a particular embodiment, the biocide is readily physisorbed onto the surface of the particles. In certain embodiments, the biocide has an electrostatic affinity for the particles. Such affinity may suitably be due to the biocide and the particles being electrostatically complementary (i.e. one bears positive charge whilst the other bears negative charge). Such electrostatic complementarily may suitably be due to complementary zeta potentials (e.g. one has a negative zeta potential whilst the other has a positive zeta potential). The particles may therefore be chosen or prepared in a manner to impart the relevant complementary zeta potential. The biocide may be chosen to electrostatically complement the particles (e.g. the biocide may comprise a cationic moiety where the particles have either an anionic moiety or a negative zeta potential at the surface).

[0093] 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).

[0094] The biocide may comprise a preservative, suitably which further improves the residual biocidal activity of the biocide and/or biocidal composition.

Preservative

[0095] The biocidal coating composition may optionally comprise a preservative. Any suitable preservative known in the art may be used. The preservative preferably gives a broad spectrum activity against transient micro-organisms.

[0096] 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. Other preservative formulations are suitable.

[0097] In some embodiments, one or more such preservatives may be present.

[0098] Though the preservative may be added to the biocidal composition as a separate ingredient, the preservative may also be a component part of any one of the other ingredients, for example, of the biocide. In some embodiments, the biocidal coating composition may comprise a preservative as a component part of the biocide, and also an additional preservative.

[0099] In some embodiments, the presence of a preservative is thought to further improve residual biocidal activity.

Particles

[00100] In accordance with the present invention, the particles have a particle size less than or equal to 1 μηι. Any particles larger than this are not considered particles in the context of the present invention because, generally speaking, particles larger than 1 μηι are too large to penetrate and settle within the small surface crevices which need to be accessed to obtain the benefits of the present invention. As such, larger particles tend to produce a separate external coating on a surface, which is thereby less durable and more prone to cracking.

[00101 ] The particles may be spherical or irregular, in which case their "particle size" is respectively defined by either the particle diameter (for spherical particles) or the largest distance between two points on the particle (for irregular-shaped particles).

[00102] The particles suitably have a particle size of less than or equal to 700 nm. Above this size, an aqueous dispersion of said particles is typically cloudy, which is less aesthetically acceptable from a consumer point of view. In a particular embodiment, the particles have a particle size of less than or equal to 500 nm, and suitably less than or equal to 400 nm. In a particular embodiment, the particles have a particle size between 150 and 250 nm.

[00103] The particles suitably have a particle size of greater than or equal to 100 nm. This is often desirable from a safety point of view, both to the manufacturer and end user of a product comprising said particles.

[00104] The particles may suitably form a (substantially) clear and transparent dispersion when mixed with water, suitably as a 0.5 wt% dispersion in water, suitably as a 2 wt% dispersion in water.

[00105] The particles may suitably have an affinity for the biocide in the biocidal coating or composition, suitably by virtue of the surface area of the particles, by virtue of a chemical or physical (including electrostatic) attraction, or by a combination of any or all of these factors. The affinity may be the result of complementary zeta potentials between the particles and the biocide (e.g. one has a negative zeta potential whilst the other has a positive zeta potential). The biocide may be suitably resistant to being washed away from the polymer film, especially when a part of the biocidal coating upon the substrate.

[00106] The particles may suitably have an affinity for the surface of the substrate, suitably by virtue of the surface area of the particles, by virtue of a chemical or physical (including electrostatic) attraction, or by a combination of any or all of these factors. The affinity may be the result of complementary zeta potentials between the particles and the surface (e.g. one has a negative zeta potential whilst the other has a positive zeta potential). The polymer film may be suitably resistant to being washed away from the surface.

[00107] The particles are suitably adherent to the surface of the substrate. The particles are suitably transparent, and suitably do not yellow within 30 days of application of the biocidal coating to the substrate, suitably not within 365 days, suitably not within 3 years. The particles suitably have substantially no effect on the appearance and/or texture of the substrate to which they are applied. The particles are suitably abrasion resistant (i.e. do not rub off when formed into a film). The particles are suitably hydrophilic. The particles are suitably resistant to hydrolysis, suitably to an alkaline wash, suitably to an alkaline wash at pH 7-12 at 90°C for 1 hour, suitably for 5 hours, suitably for 20 hours, suitably for 50 hours. The particles suitably form a film at room temperature. The polymer film so formed may be suitably self-crosslinking.

[00108] When included in the biocidal coating upon a substrate, the particles may suitably coalesce and become an integral part of the surface of the substrate, suitably holding the biocide in place.

[00109] Suitably the particles comprise a polymer or co-polymeric material (i.e. the particles are suitably polymeric particles). Suitable particles may be selected from particles comprising any one of the following: polyamide, polyester, polyethylene oxide, polyurethane, polyvinylpyrrilidone, polyacrylate, polymethacrylate, polyurethane, polyvinyl alcohol, epoxy resins, polyglycols, polysiloxanes polysaccharides, and polymers referred to as 'polyquaterniums'. These polymers, and others not mentioned here, may be present on their own, in blends, or as copolymers or derivatives.

[00110] Preferred particles are particles of polyurethane, polyacrylate polyvinylpyrrilidone, ,their copolymers and derivatives.

[00111 ] In a particular embodiment, the particles are polyurethane particles, which are especially durable and abrasion resistant, and provide very smooth films, particularly over a fibrous product. [00112] The particles are suitably insoluble, or substantially insoluble, in any diluent employed in their application to the surface of the substrate, especially water. Certain particles when coalesced into a film have the ability to self cross-link, giving a more durable and abrasion resistant polymer film.

[00113] The particles are suitably film-forming particles.

[00114] 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, the film- forming particles 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.

[00115] "Film-forming particles" are small particulates which are able to produce a film over a surface of a substrate when appropriately applied thereto. In accordance with the invention, such film-forming particles have a particle size less than or equal to 1 μηι.

Silanes and Siloxanes

[00116] 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.

[00117] 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.

[00118] 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.

[00119] 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.

[00120] 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.

[00121 ] Following application to the surface of a substrate, the compositions form a durable micro or nanofilm of biocide on the coated surface.

[00122] The applicant has found that silane oligomers, (many with functional amino groups), do possess some antimicrobial activity (mainly fungicidal) in their own right.

[00123] 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.

[00124] 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.

[00125] In an embodiment, the silane oligomer comprises 2 to 15 monomer units.

[00126] In a further embodiment, the silane oligomer comprises 2 to 10 monomer units.

[00127] In an embodiment, the organofunctional silane oligomer is formed by the condensation of a silane monomer of the formula:

Q M

R Si R₃

R₂

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

M is absent or a linker (e.g. 1 -10C alkylene);

at least one of Ri , R₂ and R₃ is hydroxyl and the others are selected from halo, hydroxyl, 1 -10C alkyl, 2-10C alkenyl and 2-1 OC alkynyl, M OCalkoxy.

[00128] Suitably, Ri , R₂ and R₃ are hydroxyl.

[00129] 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.

[00130] M may be any suitable linker group known in the art. Suitably M is alkylene, especially a 1 -5C alkylene.

[00131 ] 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.

[00132] In a further embodiment, the organofunctional silane oligomer is silsesquioxane. Silsesquioxanes are known in the art and possess the empirical formula RSiOi.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.

[00133] 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.

[00134] Silsesquioxanes can provide a range of three dimensional forms, including a polyhedral cage structures and ladder structures.

[00135] 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.

[00136] A typical structure of di odal silane is shown below

[00137] 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.

[00138] The X group is hydrolysable (typically alkoxy, acyloxy or chlorine) and enables the silicon group to bond with inorganic substrates.

[00139] Commercial examples of suitable silanes include Dynasylan from Evonik, Vitolane from TWI Cambridge and Dipodal Silanes from Gelest Inc.

[00140] 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.

[00141 ] 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).

Kit of Parts

[00142] In a third aspect of the present invention there is provided a kit of parts, comprising a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

[00143] 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 particles 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 particles may be a composition, for instance comprising a diluent as described herein. The diluents used in the biocide and the film- forming particle parts may be the same or different. Either one or both of the parts comprising the biocide or the particles may comprise additional ingredients of the biocidal coating, as described herein. Alternatively, additional ingredients may form a separate part(s) of the kit.

[00144] 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

[00145] 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 particles 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.

[00146] 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.

[00147] In another embodiment, step i) is followed by step ii). Suitably the particles applied in step i) are 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.

[00148] 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 particles are applied. In such a method, for example, the kit of parts described herein may be employed.

[00149] 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 particles remaining in place upon the surface even after the biocidal activity has diminished (perhaps due to depletion of the biocide on the surface), and as such the particles 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 particles with the biocide. [00150] 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.

[00151 ] 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.

[00152] 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 particles to form a film, e.g. by coalescing and/or cross-linking.

[00153] 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.

[00154] Traditionally in textiles the fabric the polymer particles may be applied with a suitably resin (e.g. DHDMEU) and a catalyst and cured at 130 - 150°C for 1 - 5 minutes.

[00155] 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 described above) with the biocidal coating as described above.

Applications of Biocidal Coatings and Compositions

[00156] 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.

[00157] 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.

[00158] 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. [00159] 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.

[00160] 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.

[00161 ] 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.

[00162] 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.

[00163] A further aspect of the invention provides a use of particles to bind a biocide to a surface of a substrate, comprising, simultaneously or in any sequential order, the steps of i) applying the particles 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, wherein the particles have a particle size of less than or equal to 1 μηι.

EXAMPLES

Materials

[00164] 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.

[00165] Alkyldimethylbenzylammonium chloride (ADBAC), which was employed as a biocide, was obtained commercially as, for example Barquat DM50, a 50% strength liquid from Lonza.

[00166] Didecyldimethylammonium chloride (DDAC), which was employed as a biocide, was obtained commercially as a Bardac 22, a 40 or 50% liquid from Lonza. [00167] Bromonitropropanediol, which was employed as a biocide, was obtained commercially as Bronopol in solid form from BASF.

[00168] A preservative Nipaguard PO-05 was commercially available from Clariant.

[00169] An amphoteric polyurethane film-forming agent Baypret™ USV was obtained from Tanatex Chemicals This is a 40 wt% aqueous micro-emulsion of polyurethane containing polyurethane particles with an average particle size of 0.2μηι.

[00170] A silane oligomer Dynasylan 2909 was obtained as a 40% liquid from Evonik.

[00171 ] Colalipid C, employed as a non-irritant phospholipid, a softener, and mild biocide, was commercially obtained from Colonial Chemicals Inc.

[00172] 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

[00173]

- 0.1 % PHMB

- 0.5% ADBAC

- 0.4% DDAC

- 0.1 % Bronopol

- 0.8% Nipaguard PO-05

- 0.2% EDTA

97.9% Deionised Water

[00174] The composition was applied to a surface with a clean dry cloth and allowed to dry. The appearance of the surface was not changed.

[00175] In alternative embodiments, in different applications the ingredients, both active and non active can be replaced added to, or omitted. Example 2 - Hard surface biocidal compositions

Composition 2

[00176]

0.3% Stabilised glutaraldehyde

2.0% Baypret USV

2.0% Dynasylan 2909

95.7% Deionised Water

Application to hard surface

[00177] The above composition was sprayed onto a hard surface and wiped with a dry clean cloth. The trial was stopped at this point as the results showed the composition did not pass the testing stage.

Example 3 - Hard surface and textiles biocidal compositions

[00178] A biocidal coating composition for hard surfaces and textile-based substrates was prepared by admixing the following ingredients to form a clear transparent micro-emulsion.

Composition 3

[00179]

- 0. .1 % PHMB

- 0. .5% ADBAC

- 0. .4% DDAC

- 0. .1 % Bronopol

- 0. .8% Nipaguard PO-05

- 2. .0% Baypret USV (polyurethane polymer)

- 2. .0% Dynasylan 2909 (silane oligomer)

- 0. .2% EDTA Application to hard surface

[00180] The above composition was sprayed onto a hard surface, wiped with a dry clean cloth and allowed to dry. The appearance of the surface was not changed, and no detrimental effect was observed.

[00181 ] The application method could be by spraying, wiping, brushing, misting, fogging, or in the case of textiles, by padding or exhausting.

Application to textiles

[00182] This composition was applied to a woven textile by submerging the textile within the composition for 10 seconds squeezed between rollers (with a 100% expression) dried, and oven cured for 3 minutes at 150°C. No discernable change in appearance or texture was observed after treatment with the biocidal coating composition.

Example 4 - Antimicrobial testing

Protocols

[00183] 9 stainless steel samples were tested, which were labelled "control", 1 -3, and 1 W - 3W, the latter being washed versions of duplicate samples 1 -3. The steel samples were 5cm² square swatches of 10mm thickness

[00184] 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 3, the ingredients are listed in the table below) for 10 mins, before removing the samples and allowing them to air dry.

[00185] The treated samples were then divided into two lots, and marked 1 to 3 ORIGINAL and 1 to 3 WASHED (designated by a 'W').

[00186] 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. [00187] The details for each sample are shown in Table 1 below, and correspond to the compositions described hereinbefore.

Table 1

[00188] 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.

[00189] 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.

[00190] 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.

[00191 ] 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. [00192] 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.

[00193] The number of bacteria extracted from the samples was calculated by:

(Number of Bacteria) = (Colony Number) x 10 x (Dilution Factor).

[00194] 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

[00195] The results of the antimicrobial tests are shown in Table 2 below.

Table 2

Sample Description S.aureus recovered Log reduction (B/C) No.

(time taken)

Control No coating 1 .18 x 10⁵ (t=0) n/a

5.10 x 10⁴ (t=23h)

1 PHMB/QUAT only <10 (t=23h) 3.71

2 Glutaraldehyde + silane + 1 .05 x 10⁵ (t=23h) -0.31

polyurethane

3 PHMB/QUAT + silane + <10 (t=23h) 3.71

polyurethane

1W PHMB/QUAT only 1 .12 x 10⁴ ( t=23h) -0.34

2W Glutaraldehyde + silane + 1 .27 x 10^s (t=23h) -0.40

polyurethane

3W PHMB/QUAT + Silane + <10 (t=23h) 3.71

polyurethane Conclusions

Composition 1

[00196] 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

[00197] The biocide here was glutaraldehyde which gave a poor result both before and after, washing. The implication is that the glutaraldehyde reacted with either the amino group of the silane (Dynasylan 2909) and/or the urethane group of the polyurethane (Baypret USV) rendering biocidal action ineffective. As the mode of action of glutaraldehyde involves reactions with amino or amido group of the pathogens protein thereby killing them, glutaraldehyde was not free to act as a biocide.

Composition 3

[00198] This was as per Composition 1 but with the addition of silane (Dynasylan 2909) and polyurethane (Baypret USV). As it can be seen the Composition gave a good result both before and after washing, thus demonstrating that the Composition possess residual activity.

Example 5 - Coating of Fibres

[00199] Brief tests were conducted upon textile fibres to assess the film-forming characteristics of different film-forming polymers.

[00200] Tests were conducted by dipping a series of textile fibres in aqueous dispersions/solutions of polyurethane (PU), polyvinylpyrrolidone (PVP), polyvinyl acetate and acrylate film-forming polymers, squeezing out the excess liquid, then allowing the fibres to air dry.

[00201 ] Polyvinyl acetate gave a stiff finish which was not sufficiently abrasion resistant.

[00202] Polyacrylate polymers were found to be good film-formers, with reasonable abrasion resistance, but affected the properties of the substrate. [00203] However, polyurethane performed best, giving excellent abrasion resistance, appearance and texture following coating of textile fibres (and other surfaces).

[00204] By way of comparison, FIG. 1 (showing a polyacrylate-coated fibre) and FIG. 2 (showing a polyurethane-coated fibre) clearly demonstrate the superiority of polyurethane as a film-forming agent of the present invention. The polyacrylate resin is thinly coated onto the fibre, but when the fibre is stressed by knotting, as shown, the polyacrylate film cracks under the stress. The polyurethane-coated fibre, however, does not crack under the same stress, and instead forms a smooth thin film over the fibre.

Claims

CLAIMS:

1 . A biocide-coated substrate, comprising a substrate surface that is coated with a biocidal coating; wherein the biocidal coating comprises a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

2. The biocide-coated substrate as claimed in claim 1 , wherein the substrate is non- textile based.

3. The biocide-coated substrate as claimed in claim 1 , wherein the substrate is textile-based.

4. The biocide-coated substrate as claimed in claim 3, wherein the biocidal coating is free from plasticizers.

5. The biocide-coated substrate as claimed in any preceding claim, wherein the biocidal coating comprises a silane or siloxane.

6. The biocide-coated substrate as claimed in claim 5, wherein the silane or siloxane is an organofunctional silane oligomer formed by the condensation of a silane monomer of the formula:

Q M

R Si R₃

R₂

wherein:

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

M is absent or a linker (e.g. 1 -10C alkylene);

at least one of Ri , R₂ and R₃ is hydroxyl and the others are selected from halo, hydroxyl, 1 -10C alkyl, 2-10C alkenyl and 2-10C alkynyl, M OCalkoxy.

7. The biocide-coated substrate as claimed in any preceding claim, wherein the particles have a particle size between 150 and 250 nm.

8. The biocide-coated substrate as claimed in any preceding claim, wherein the particles are particles comprising any one of the following: polyamide, polyester, polyethylene oxide, polyurethane, polyvinylpyrrilidone, polyacrylate, polymethacrylate, polyurethane, polyvinyl alcohol, epoxy resins, polyglycols, polysiloxanes polysaccharides, and polymers referred to as 'polyquaterniums'.

9. The biocide-coated substrate as claimed in claim 8, wherein the particles are particles of polyurethane, polyacrylate polyvinylpyrrilidone, their copolymers and derivatives.

10. The biocide-coated substrate as claimed in claim 9, wherein the particles are polyurethane particles.

1 1 . The biocide-coated substrate as claimed in any preceding claim, wherein the particles are film-forming particles.

12. The biocide-coated substrate as claimed in any preceding claim, wherein the biocide is selected from the group including quaternary ammonium compounds, biguanides, guanidines, glutaraldehyde, formaldehyde, iodophors, chlorines, phenol derivatives, amines, metal salts, organometallic compounds, Bronopol, oxidising agents, acids, alkalis, etc., and are present in the soluble or insoluble form.

13. biocide-coated substrate as claimed in any preceding claim, wherein the biocide is PHMB.

14. A biocidal coating composition, comprising a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

15. The biocidal coating composition as claimed in claim 14, wherein the composition is 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.

16. The biocidal coating composition as claimed in claim 15, wherein the composition is a hand-wash.

17. The biocidal coating composition as claimed in claim 16, wherein the hand-wash is free from silanes or siloxanes.

18. The biocidal coating composition as claimed in any of claims 14 to 17, wherein the composition comprises:

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

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

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

19. A kit of parts, comprising a biocide and particles, the particles having a particle size of less than or equal to 1 μηι.

20. A method of coating a substrate with a biocidal coating, the method comprising, simultaneously or in any sequential order, the steps of i) applying particles 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; wherein the particles have a particle size of less than or equal to 1 μηι.

21 . A use of the biocidal coating composition of any of claims 14 to 18, or kit of parts of claim 19 for coating a substrate, for providing a substrate with biocidal activity, or for providing a substrate with long-term residual biocidal activity.

22. A use of particles to bind a biocide to a surface of a substrate, comprising, simultaneously or in any sequential order, the steps of i) applying the particles 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; wherein the particles have a particle of less than or equal to 1 μηι.