Title of Invention	A BIOSTATIC COMPOSITION SUITABLE FOR APPLICATION TO HARD SURFACES TO INHIBIT BIOFILM GROWTH
Abstract	A biostatic coating comprising a coating composition which on drying produces an intrinsically hydrophobic film. The coating composition includes a biocidal complex A-B in which A is a phenolic biocide and B is selected from polyvinylpyrrolidone ("PVP"), PVP polymers, PVP copolymers and mixtures thereof. The coating composition for example is selected from acrylic and methacrylic polymer based compositions, acrylic and methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. Suitable biocides for use in the invention include, but are not limited to complexes of PVP or PVP copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers.

Title of Invention

A BIOSTATIC COMPOSITION SUITABLE FOR APPLICATION TO HARD SURFACES TO INHIBIT BIOFILM GROWTH

Abstract

A biostatic coating comprising a coating composition which on drying produces an intrinsically hydrophobic film. The coating composition includes a biocidal complex A-B in which A is a phenolic biocide and B is selected from polyvinylpyrrolidone ("PVP"), PVP polymers, PVP copolymers and mixtures thereof. The coating composition for example is selected from acrylic and methacrylic polymer based compositions, acrylic and methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. Suitable biocides for use in the invention include, but are not limited to complexes of PVP or PVP copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers.

Full Text	Technical Field This invention relates to a method of, and composition for, reduction or prevention of biofilm formation on moist or wet surfaces, and more particularly to the reduction of pathogens in, and in the vicinity of, air-conditioning systems. The invention has been developed primarily for use in air-conditioning (including air cooling and air heating) systems, and will be described hereinafter with reference to this field of use. However, it will be appreciated that the invention can be applied in other situations in which it is desired to inhibit biofilm formation or micro-organism colonization of a surface. Background Art Air conditioning systems such as are commonly provided in office, residential, health care and other buildings frequently include components with moist or wet surfaces. A good example is the air conditioner condenser which may comprise a plurality of heat exchange fins, for example of aluminium construction, cooled by heat conductive connection with a recirculating refrigerant. Hot air to be cooled is passed over the fins, and moisture in the air condenses on the fins and drains away. In some cases the heat exchange surfaces of the condenser are cooled by a recirculating thin film of water. The cooling surfaces are typically of a large area, are moist or wet, and provide an ideal environment for the immobilization and growth of micro-organisms which are carried by the air and which form biofilms on the surfaces. The micro-organisms include bacteria and fungi which multiply on the surface. Within months the space between adjacent heat exchange surfaces may be totally occluded by biofilm growth. Biofilm reduces efficacy and poses major health risks. Efficacy is lost because the biofilm has poor heat transfer properties and so the thermal efficiency of the condenser is diminished. Microbial activity can also shorten the service life of a system because acidic bacterial exudates can cause serious corrosion and because the increase in biomass on, and in, the components can lessen air-flow and increase back pressure in the system, requiring maintenance cleaning after a short life in service. The health risk arises because the presence of biofilm in turn provides a haven for the further accumulation and further growth of pathogens such as fungi, bacteria, viruses, allergens, yeasts, and moulds. Conditions for the growth of such organisms are especially favourable during periods of high humidity such as may occur when the system is off, for example at night, but also arise during normal operation. The presence of organisms is highly undesirable because they can cause illness or death in humans and animals, create odours and can damage or destroy a wide variety of materials. Of particular concern in terms of human health and safety are endotoxins and mycotoxins which are breakdown components of fungal and bacterial cell walls and which are known human respiratory allergens. In some individuals they can trigger asthma attacks, and in all cases have been shown to cause immune response. It is currently thought that over a period of exposure this reduces the ability of the immune system to respond to antagonists and leaves the subject more prone to infection by bacteria, viruses, etc. Also of concern are fungal spores, bacterial spores and bacteria. In health care facilities such as hospitals and nursing homes the adverse consequences of release of endotoxins and myotoxins from biomass are exacerbated because many of the patients are in a weakened condition due to their primary health care problem. Micro-organisms that would not be a major threat to a healthy person can be fatal to a patient with a diminished capacity to defend themselves from infection. Increasing attention is also being paid to other environments such as public buildings, since if pathogenic micro-organisms find their way via conditioned air or ventilation shafts, into a building they can be rapidly circulated throughout the building thereby since if pathogenic micro-organisms find their way via conditioned air or ventilation shafts, into a building they can be rapidly circulated throughout the building thereby greatly increasing the likelihood of the spread of infection and disease. The prevention of spore germination and microbial survival in air conditioning systems would help reduce the risk of illness and hypersensitivity reactions. To date there has been no effective means of prevention of biomass growth and the only means of addressing the problem has been periodic cleaning, which is labour intensive, costly and inconvenient and which does not adequately deal with health concerns between cleaning operations. Although various coating materials have been proposed, none have been able to resist the moist conditions or remain effective in preventing biofilm formation for a useful period. It is an object of the present invention to overcome or ameliorate at least one of the deficiencies of the prior art, or to provide a useful alternative. Many regions of the world employ heated filtered air in buildings as a means of central heating. It will be understood that such systems contribute to the same hazards as described above for air conditioning and the invention is not limited to any particular kind of filter or airflow system. Description Of The Invention According to a first aspect the invention provides a biostatic coating composition comprising a film forming composition which on drying produces an intrinsically hydrophobic film and including a biocidal complex A-B in which A is a phenolic biocide and B is selected from polyvinylpyrrolidone, polyvinylpyrrolidone polymers, polyvinylpyrrolidone copolymers and mixtures thereof, and wherein the biocidal complex A-B is not water soluble. If it will be understood by those skilled in the art that the phrase "not water soluble" means not water soluble at the temperatures at which the composition is used. Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". According to a second aspect the invention provides a biostatic coating composition according to the first aspect wherein the coating composition is selected from acrylic polymer based compositions, methacrylic polymer based compositions, acrylic copolymer based compositions, methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. Preferably, the coating composition has bacteriostatic and/or fungistatic properties. The film forming composition may be based on an emulsion or latex, a polymer or copolymer solution, or a polymer or copolymer emulsion. The film forming composition may be a water-based polymer or copolymer emulsion. For preference, the film forming composition is or includes an acrylic polymer, acrylic copolymer, mixtures of acrylic polymers, mixtures of acrylic copolymers or mixtures of acrylic polymers and copolymers. More preferably, the film forming composition is or includes an acrylic - styrene copolymer The film forming composition may be or includes an epoxy or epoxy ester. Highly preferred coating compositions are water-based polymers or copolymer emulsion or latex compositions, and especially those including an epoxy ester. The film forming composition may be or includes a vinyl acetate acrylic copolymer. Preferably, the film forming composition is present in an amount of 30 to 80% w/w of the mixture, more preferably the film forming composition is present in an amount of 40 to 70% w/w of the mixture and even more preferably the film forming composition is present in an amount of 50 to 60% w/w of the mixture. Preferred biocides for use in the biocidal complex A-B are triclosan; diclosan; dichlorophen; orfhophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers. More preferably, biocide A is a halogenated phenolic biocide, in preference a chloro-phenolic biocide and most preferably, biocide A is triclosan. Preferably, biocide A is present in an amount of 0.5 to 5% w/w of the mixture, more preferably in an amount of 1 to 2% w/w of the mixture and even more preferably in an amount of 1.5% w/w of the mixture. Preferably, the complexing partner B is polyvinylpyrrolidone, or may be, for example, a polyvinylpyrrolidone/vinyl acetate copolymer. Preferably, B is present in an amount of 2 to 10% of the mixture, more preferably B is present in an amount of 3 to 8% of the mixture, and even more preferably B is present in an amount of about 5% of the mixture Preferably, the biostatic composition contains solvent in an amount of 20 to 40% of the mixture, more preferably 25 to 35% of the mixture. One preferred solvent is water. It has been practised to combine a PVP/phenolic complex in a hydrophilic film forming polyvinyl pyrrolidone polymer or copolymer whereby the complex may be loosely bound to impregnated paper or textile wipes for cleaning food preparation surfaces and the like. In the forgoing applications the complex is readily leached from the wipe substrate and can readily contact bacteria on the surface being cleaned/disinfected. The complex does not have any long lasting effect on the surface, and the wipe must be disposed of after approximately a dozen washes. The present applicant was thus surprised to discover that inclusion of the PVP complex in a coating composition applied on, for example, a metal or masonry surface, significantly inhibited biofilm growth on the polymer coated surface, when the coating polymer might have been expected to encapsulate the biocide and protect micro-organisms from contact with the biocide. It was even more surprising that coatings including the complex according to the invention have prevented biomass growth on coated metal for periods exceeding three years in an environment in which such growth was previously a major problem. It is also surprising that such a small concentration of biocide is effective for such a long duration. It will be appreciated that PVP/phenolic complexes are not water soluble and their inclusion in coating compositions is not simple. This has been achieved in the case of water based emulsion coating compositions by dispersing the complex in the aqueous phase together with a water soluble high boiling point polar solvent (eg N-methyl pyrrolidone or a glycol ether). After the coating is applied, and as the water evaporates, the relative proportion of the high BP polar solvent increases and at a critical point dissolves the biocidal complex leaving the biocide homogeneously distributed throughout the film. It will also be understood that while water is a preferred vehicle, dispersion in solvent based coating compositions can be similarly achieved. According to a third aspect, the invention provides a biostatic composition according to the first or second aspects further including a water soluble polar solvent having a higher boiling point than a solvent vehicle of the coating composition. Preferably, the high boiling polar solvent aids dispersion of the complex A-B in a polymer emulsion or latex. Preferably, the water soluble polar solvent is selected from N- methyl pyrrolidone, glycol ethers, and combinations thereof. Coatings according to the invention may be used as protective coatings on components susceptible to biomass growth , such as air conditioning condenser plates, vents and on other surfaces, eg susceptible surfaces in operating theatres, to prevent the formation of biofilm on the surface. The invention may also be applied in decorative coatings such as paints to prevent mould growth on susceptible surfaces. Coatings according to the invention may be applied (without limitation to surfaces of metal, masonry, timber, particle board, and other building and construction materials). Some compositions may desirably be baked onto the surface or dried at elevated temperatures. According to a third aspect, the invention provides a biostatic coating formed by drying a film or thin layer of a biostatic coating composition according to any one of the preceding aspects. The coating is preferably effective to prevent biofilm growth on its surface for in excess of one year, and even more preferably is effective to prevent biofilm growth on its surface for in excess of three years. The coating may be applied to metal, to concrete or a cementitious surface or to a timber surface. The coating may be applied in the form of a decorative coating. One example is in the form of a paint to prevent mould growth. Such a paint can further include paint ingredients selected from the group consisting of suspension agents, thixotropic agents, flow and viscosity modifiers, preservatives and the like. Other paint ingredients may be advantageously selected from the group consisting of corrosion inhibitors and/or pigments. Thus depending on intended end use, compositions according to the invention may be pigmented and in that case will normally include other paint ingredients such as suspension agents, thixotropic agents, flow and viscosity modifiers, preservatives and the like. The compositions need not be pigmented and may include corrosion inhibitors and other additives known to be useful in film-forming coatings. It will be understood that it is sufficient that the treatment is bacteriostatic or fungistatic. That is to say, it is sufficient that the treating agent stops colonisation on the surface rather than kills organisms on a colonised surface. According to a fourth aspect, the invention provides a method of inhibiting the formation of a biofilm on a surface susceptible to such formation comprising the steps of applying a coating of a composition according to the first or second aspects to the surface and drying the composition or allowing the composition to dry. In preferred embodiments, the surface is an air conditioning surface, an air conditioning condenser plate, an air conditioning condenser vent, or may be a susceptible surface in an operating theatre. In some embodiments, the composition is baked onto the surface or dried at elevated temperatures. According to a fifth aspect, the invention provides a surface treated in accordance with a composition of the fist or second aspects or according to a method of the fourth aspect. Best Modes for Carrying Out the Invention Various embodiments of the invention will now be more particularly described by way of example only. Suitable biocides for use in the invention include, but are not limited to complexes of PVP or PVP copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers. Examples of formulas: Formulations were prepared as shown in the following examples Example 1 Styrene/Acrylic Copolymer Emulsion(50% solids) 60.0%w/w Water 28.5% w/w N-Methyl Pyrrolidone 5.0% w/w PVP/VA S-630 5.0% w/w Triclosan 1.5% w/w Example 2 Acrylic Copolymer Emulsion(50% solids) 60.0%w/w Water 28.5% w/w N-Methyl Pyrrolidone 5.0% w/w PVP/VA S-630 5.0% w/w Triclosan 1.5% w/w Example 3 Vinyl Acetate/Acrylic Copolymer Emulsion 60.0%w/w (50% solids) Water 28.5% w/w N-Methyl Pyrrolidone 5.0% w/w PVP/VA S-630 5.0% w/w Triclosan 1.5% w/w Example 4 Acrylic Copolymer Emulsion 30.0 - 50.0%w/w (50% solids) Epoxy Resin 1001 10.0 - 20.0% w/w Propylene Glycol Methyl Ether Acetate 10.0 - 20.0% w/w PVP/VA S630 5.0%w/w 2-Phenoxy Ethanol 2.0-5.0% w/w Nonyl Phenol Ethoxylate Sulphate Ammonium Salt 2 - 3.0% w/w Triclosan 1.5% w/w Example 5 Acrylic copolymer 70% w/w (50% active solution in ethanol) PVP/VA S630 5.0%w/w Triclosan 1.5% w/w Ethanol 23.5% w/w PVP/VA S630 is available from ISP corporation. A cooling coil in the airconditioning system of a large city building situated in Sydney was thoroughly cleaned and then monitored at intervals over a 12 month period. A significant growth of biomass was observable on the cooling coil within a month, and the coil required cleaning at intervals of approximately 3 months. The coil was then again cleaned and sections of the coil were coated with formulations according to each of examples 1-3. The coil was inspected at intervals. No biofilm growth was observable on the coil after 12 months on any of the coated sections. 1. A biostatic composition suitable for application to surfaces and effective to inhibit biofilm growth for at least 12 months when the surface is moist or wet, the composition comprising: a film forming combination of a biocidal complex A-B in which A is a phenolic biocide and B is selected from the group consisting of polyvinylpyrrolidone polymers, polyvinylpyrrolidone copolymers and mixtures thereof; and wherein B is selected so that the biocidal complex A-B is not water soluble but is dispersed in a water based emulsion by inclusion of a polar solvent or is dispersed in a solvent based vehicle; wherein the composition dries to a water insoluble coating when applied to surfaces. 2. A biostatic coating composition according to claim 1 wherein the film forming combination is selected from acrylic polymer based compositions, methacrylic polymer based compositions, acrylic copolymer based compositions, methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. 3. A biostatic coating composition according to claim 1 which has bacteriostatic properties. 4. A biostatic coating composition according to claim 1 or claim 2 which has fungistatic properties. 5. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition is an emulsion or latex composition. 6. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition is a polymer or copolymer solution. 7. A biostatic coating composition according to any one of claims 1 to 5 wherein the film forming coating composition is a polymer or copolymer emulsion. 8. A biostatic coating composition according to claim 7 wherein the film forming coating composition is a water-based polymer or copolymer emulsion. 9. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition is or includes an acrylic polymer or acrylic copolymer 10. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition is or includes an acrylic - styrene copolymer 11. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition is or includes an epoxy or epoxy ester. 12. A biostatic coating composition according to any one of the preceding claims wherein the film forming coating composition includes a vinyl acetate acrylic copolymer. 13. A biostatic composition according to any one of the preceding claims wherein the film forming composition is present in an amount of 30 to 80% w/w of the mixture. 14. A biostatic composition according to any one of the preceding claims wherein the film forming composition is present in an amount of 40 to 70% w/w of the mixture. 15. A biostatic composition according to any one of the preceding claims wherein the film forming composition is present in an amount of 50 to 60% w/w of the mixture. 16. A biostatic coating composition according to any one of the preceding claims wherein biocide A is selected from the group consisting of triclosan; diclosan; dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers. 17. A biostatic coating composition according to any one of the preceding claims wherein biocide A is a halogenated phenolic biocide. 18. A biostatic coating composition according to any one of the preceding claims wherein the biocide A is triclosan. 19. A biostatic composition according to any one of the preceding claims wherein the biocide A is present in an amount of 0.5 to 5% w/w of the mixture. 20. A biostatic composition according to any one of the preceding claims wherein biocide A is present in an amount of 1 to 2% w/w of the mixture. 21. A biostatic composition according to any one of the preceding claims wherein biocide A is present in an amount of 1.5% w/w of the mixture. 22. A biostatic coating composition according to any one of the preceding claims wherein B is polyvinylpyrrolidone. 23. A biostatic coating composition according to any one of the preceding claims wherein B is polyvinylpyrrolidone/vinyl acetate copolymer 24. A biostatic coating composition according to any one of the preceding claims wherein B is present in an amount of 2 to 10% of the mixture 25. A biostatic coating composition according to any one of the preceding claims wherein B is present in an amount of 3 to 8% of the mixture 26. A biostatic coating composition according to any one of the preceding claims wherein B is present in an amount of about 5% of the mixture 27. A biostatic composition according to any one of the preceding claims containing solvent in an amount of 20 to 40% of the mixture. 28. A biostatic composition according to claim 27 wherein the solvent is present in an amount of 25 to 35% of the mixture. 29. A biostatic composition according to claim 27 or 28 wherein the solvent is water. 30. A biostatic composition according to any one of claims 27 to 29 further including a water soluble polar solvent having a higher boiling point than a solvent vehicle of the coating composition. 31. A biostatic composition according to claim 30 wherein the high boiling polar solvent aids dispersion of the complex A-B in a polymer emulsion or latex. 32. A biostatic composition according to claim 30 or 31 wherein the water soluble polar solvent is selected from N-methyl pyrrolidone, glycol ethers, and combinations thereof. 33. A biostatic coating formed by drying a film or thin layer of a biostatic coating composition on a surface, wherein the biostatic coating composition is suitable for application to surfaces and is effective to inhibit biofilm growth on the surface when the surface is moist or wet for at least 12 months; wherein the composition dries to a water insoluble coating effective to inhibit biofilm growth on the surface when applied to the surface; and wherein the composition comprises a film forming combination of a biocidal complex A-B in which A of the biocidal complex A-B is a phenolic biocide and B of the biocidal complex A-B is selected from the group consisting of polyvinylpyrrolidone polymers, polyvinylpyrrolidone copolymers, and mixtures thereof, and wherein B is selected so that the biocidal complex A-B is not water soluble but is dispersed in a water based emulsion by inclusion of a polar solvent or is dispersed in a solvent based vehicle. 34. A biostatic coating according to claim 33 which is effective to prevent biofilm growth on its surface for in excess of one year 35. A biostatic coating according to claim 34 which is effective to prevent biofilm growth on its surface for in excess of three years. 36. A biostatic coating according to any one of claims 33 to 35 when applied to metal 37. A biostatic coating according to any one of claims 33 to 35 when applied to concrete or a cementitious surface. 38. A biostatic coating according to any one of claims 33 to 35 when applied to a timber surface. 39. A biostatic coating according to any one of claims 33 to 38 in the form of a decorative coating. 40. A biostatic coating according to any one of claims 33 to 39 in the form of a paint to prevent mould growth. 41. A biostatic coating according to any one of claims 33 to 40 in the form of a paint further including paint ingredients selected from the group consisting of suspension agents, thixotropic agents, flow and viscosity modifiers, preservatives and the like. 42. A biostatic coating according to any one of claims 33 to 41 in the form of a paint further including paint ingredients selected from the group consisting of corrosion inhibitors. 43. A biostatic coating according to any one of claims 33 to 42 in the form of a paint further including a pigment. 44. A method of inhibiting the formation of a biofilm on a surface susceptible to such formation when the surface is moist or wet, the method comprising the steps of: applying a coating of a biostatic composition to the surface; and drying the biostatic composition or allowing the composition to dry, wherein the biostatic composition of the coating comprises a film forming combination of a biocidal complex A-B in which A of the biocidal complex A-B is a phenolic biocide and B of the biocidal complex A-B is selected from the group consisting of polyvinylpyrrolidone polymers, polyvinylpyrrolidone copolymers, and mixtures thereof, and wherein B is selected so that the biocidal complex A-B is not water soluble but is dispersed in a water based emulsion by inclusion of a polar solvent or is dispersed in a solvent based vehicle, and wherein the biostatic composition dries to a water insoluble coating 45. A method according to claim 44 wherein the surface is an air conditioning surface. 46. A method according to claim 44 wherein the surface is an air conditioning condenser plate. 47. A method according to claim 44 wherein the surface is an air conditioning condenser vent. 48. A method according to claim 44 wherein the surface is a susceptible surface in an operating theatre. 49. A method according to any one of claims 44 to 48 wherein the composition is baked onto the surface or dried at elevated temperatures. 50. A surface treated in accordance with a composition of any one of claims 1 to 32 or according to a method of any one of claims 44 to 49. Abstract Biofilm Growth Prevention A biostatic coating comprising a coating composition which on drying produces an intrinsically hydrophobic film. The coating composition includes a biocidal complex A-B in which A is a phenolic biocide and B is selected from polyvinylpyrrolidone ("PVP"), PVP polymers, PVP copolymers and mixtures thereof. The coating composition for example is selected from acrylic and methacrylic polymer based compositions, acrylic and methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. Suitable biocides for use in the invention include, but are not limited to complexes of PVP or PVP copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers.

Full Text

Technical Field
This invention relates to a method of, and composition for, reduction or prevention
of biofilm formation on moist or wet surfaces, and more particularly to the reduction of
pathogens in, and in the vicinity of, air-conditioning systems. The invention has been
developed primarily for use in air-conditioning (including air cooling and air heating)
systems, and will be described hereinafter with reference to this field of use. However, it
will be appreciated that the invention can be applied in other situations in which it is
desired to inhibit biofilm formation or micro-organism colonization of a surface.
Background Art
Air conditioning systems such as are commonly provided in office, residential,
health care and other buildings frequently include components with moist or wet surfaces.
A good example is the air conditioner condenser which may comprise a plurality of heat
exchange fins, for example of aluminium construction, cooled by heat conductive
connection with a recirculating refrigerant. Hot air to be cooled is passed over the fins,
and moisture in the air condenses on the fins and drains away. In some cases the heat
exchange surfaces of the condenser are cooled by a recirculating thin film of water.
The cooling surfaces are typically of a large area, are moist or wet, and provide an
ideal environment for the immobilization and growth of micro-organisms which are
carried by the air and which form biofilms on the surfaces. The micro-organisms include
bacteria and fungi which multiply on the surface. Within months the space between
adjacent heat exchange surfaces may be totally occluded by biofilm growth.
Biofilm reduces efficacy and poses major health risks. Efficacy is lost because the
biofilm has poor heat transfer properties and so the thermal efficiency of the condenser is
diminished. Microbial activity can also shorten the service life of a system because acidic
bacterial exudates can cause serious corrosion and because the increase in biomass on, and
in, the components can lessen air-flow and increase back pressure in the system, requiring
maintenance cleaning after a short life in service.

The health risk arises because the presence of biofilm in turn provides a haven for
the further accumulation and further growth of pathogens such as fungi, bacteria, viruses,
allergens, yeasts, and moulds. Conditions for the growth of such organisms are especially
favourable during periods of high humidity such as may occur when the system is off, for
example at night, but also arise during normal operation. The presence of organisms is
highly undesirable because they can cause illness or death in humans and animals, create
odours and can damage or destroy a wide variety of materials.
Of particular concern in terms of human health and safety are endotoxins and
mycotoxins which are breakdown components of fungal and bacterial cell walls and which
are known human respiratory allergens. In some individuals they can trigger asthma
attacks, and in all cases have been shown to cause immune response. It is currently
thought that over a period of exposure this reduces the ability of the immune system to
respond to antagonists and leaves the subject more prone to infection by bacteria, viruses,
etc. Also of concern are fungal spores, bacterial spores and bacteria.
In health care facilities such as hospitals and nursing homes the adverse
consequences of release of endotoxins and myotoxins from biomass are exacerbated
because many of the patients are in a weakened condition due to their primary health care
problem. Micro-organisms that would not be a major threat to a healthy person can be
fatal to a patient with a diminished capacity to defend themselves from infection.
Increasing attention is also being paid to other environments such as public buildings,
since if pathogenic micro-organisms find their way via conditioned air or ventilation
shafts, into a building they can be rapidly circulated throughout the building thereby since
if pathogenic micro-organisms find their way via conditioned air or ventilation shafts, into
a building they can be rapidly circulated throughout the building thereby greatly
increasing the likelihood of the spread of infection and disease. The prevention of spore
germination and microbial survival in air conditioning systems would help reduce the risk
of illness and hypersensitivity reactions.

To date there has been no effective means of prevention of biomass growth and the
only means of addressing the problem has been periodic cleaning, which is labour
intensive, costly and inconvenient and which does not adequately deal with health
concerns between cleaning operations. Although various coating materials have been
proposed, none have been able to resist the moist conditions or remain effective in
preventing biofilm formation for a useful period.
It is an object of the present invention to overcome or ameliorate at least one of the
deficiencies of the prior art, or to provide a useful alternative.
Many regions of the world employ heated filtered air in buildings as a means of
central heating. It will be understood that such systems contribute to the same hazards as
described above for air conditioning and the invention is not limited to any particular kind
of filter or airflow system.
Description Of The Invention
According to a first aspect the invention provides a biostatic coating composition
comprising a film forming composition which on drying produces an intrinsically
hydrophobic film and including a biocidal complex A-B in which A is a phenolic biocide
and B is selected from polyvinylpyrrolidone, polyvinylpyrrolidone polymers,
polyvinylpyrrolidone copolymers and mixtures thereof, and wherein the biocidal complex
A-B is not water soluble.
If it will be understood by those skilled in the art that the phrase "not water
soluble" means not water soluble at the temperatures at which the composition is used.
Unless the context clearly requires otherwise, throughout the description and the
claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive
sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of
"including, but not limited to".

According to a second aspect the invention provides a biostatic coating
composition according to the first aspect wherein the coating composition is selected from
acrylic polymer based compositions, methacrylic polymer based compositions, acrylic
copolymer based compositions, methacrylic copolymer based compositions, vinyl polymer
based compositions, vinyl copolymer based compositions, epoxy resins, epoxy esters, and
mixtures thereof.
Preferably, the coating composition has bacteriostatic and/or fungistatic properties.
The film forming composition may be based on an emulsion or latex, a polymer or
copolymer solution, or a polymer or copolymer emulsion. The film forming composition
may be a water-based polymer or copolymer emulsion.
For preference, the film forming composition is or includes an acrylic polymer,
acrylic copolymer, mixtures of acrylic polymers, mixtures of acrylic copolymers or
mixtures of acrylic polymers and copolymers. More preferably, the film forming
composition is or includes an acrylic - styrene copolymer
The film forming composition may be or includes an epoxy or epoxy ester.
Highly preferred coating compositions are water-based polymers or copolymer
emulsion or latex compositions, and especially those including an epoxy ester.
The film forming composition may be or includes a vinyl acetate acrylic
copolymer.
Preferably, the film forming composition is present in an amount of 30 to 80% w/w
of the mixture, more preferably the film forming composition is present in an amount of
40 to 70% w/w of the mixture and even more preferably the film forming composition is
present in an amount of 50 to 60% w/w of the mixture.

Preferred biocides for use in the biocidal complex A-B are triclosan; diclosan;
dichlorophen; orfhophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and
substituted diphenyl ethers.
More preferably, biocide A is a halogenated phenolic biocide, in preference a
chloro-phenolic biocide and most preferably, biocide A is triclosan.
Preferably, biocide A is present in an amount of 0.5 to 5% w/w of the mixture,
more preferably in an amount of 1 to 2% w/w of the mixture and even more preferably in
an amount of 1.5% w/w of the mixture.
Preferably, the complexing partner B is polyvinylpyrrolidone, or may be, for
example, a polyvinylpyrrolidone/vinyl acetate copolymer.
Preferably, B is present in an amount of 2 to 10% of the mixture, more preferably B
is present in an amount of 3 to 8% of the mixture, and even more preferably B is present in
an amount of about 5% of the mixture
Preferably, the biostatic composition contains solvent in an amount of 20 to 40% of
the mixture, more preferably 25 to 35% of the mixture. One preferred solvent is water.
It has been practised to combine a PVP/phenolic complex in a hydrophilic film
forming polyvinyl pyrrolidone polymer or copolymer whereby the complex may be
loosely bound to impregnated paper or textile wipes for cleaning food preparation surfaces
and the like. In the forgoing applications the complex is readily leached from the wipe
substrate and can readily contact bacteria on the surface being cleaned/disinfected. The
complex does not have any long lasting effect on the surface, and the wipe must be
disposed of after approximately a dozen washes. The present applicant was thus
surprised to discover that inclusion of the PVP complex in a coating composition applied
on, for example, a metal or masonry surface, significantly inhibited biofilm growth on the
polymer coated surface, when the coating polymer might have been expected to
encapsulate the biocide and protect micro-organisms from contact with the biocide. It was

even more surprising that coatings including the complex according to the invention have
prevented biomass growth on coated metal for periods exceeding three years in an
environment in which such growth was previously a major problem. It is also surprising
that such a small concentration of biocide is effective for such a long duration.
It will be appreciated that PVP/phenolic complexes are not water soluble and their
inclusion in coating compositions is not simple. This has been achieved in the case of
water based emulsion coating compositions by dispersing the complex in the aqueous
phase together with a water soluble high boiling point polar solvent (eg N-methyl
pyrrolidone or a glycol ether). After the coating is applied, and as the water evaporates,
the relative proportion of the high BP polar solvent increases and at a critical point
dissolves the biocidal complex leaving the biocide homogeneously distributed throughout
the film. It will also be understood that while water is a preferred vehicle, dispersion in
solvent based coating compositions can be similarly achieved.
According to a third aspect, the invention provides a biostatic composition
according to the first or second aspects further including a water soluble polar solvent
having a higher boiling point than a solvent vehicle of the coating composition.
Preferably, the high boiling polar solvent aids dispersion of the complex A-B in a
polymer emulsion or latex. Preferably, the water soluble polar solvent is selected from N-
methyl pyrrolidone, glycol ethers, and combinations thereof.
Coatings according to the invention may be used as protective coatings on
components susceptible to biomass growth , such as air conditioning condenser plates,
vents and on other surfaces, eg susceptible surfaces in operating theatres, to prevent the
formation of biofilm on the surface. The invention may also be applied in decorative
coatings such as paints to prevent mould growth on susceptible surfaces. Coatings
according to the invention may be applied (without limitation to surfaces of metal,
masonry, timber, particle board, and other building and construction materials). Some
compositions may desirably be baked onto the surface or dried at elevated temperatures.

According to a third aspect, the invention provides a biostatic coating
formed by drying a film or thin layer of a biostatic coating composition according to any
one of the preceding aspects.
The coating is preferably effective to prevent biofilm growth on its surface for in
excess of one year, and even more preferably is effective to prevent biofilm growth on its
surface for in excess of three years.
The coating may be applied to metal, to concrete or a cementitious surface or to a
timber surface.
The coating may be applied in the form of a decorative coating. One example is in
the form of a paint to prevent mould growth. Such a paint can further include paint
ingredients selected from the group consisting of suspension agents, thixotropic agents,
flow and viscosity modifiers, preservatives and the like. Other paint ingredients may be
advantageously selected from the group consisting of corrosion inhibitors and/or
pigments.
Thus depending on intended end use, compositions according to the invention may
be pigmented and in that case will normally include other paint ingredients such as
suspension agents, thixotropic agents, flow and viscosity modifiers, preservatives and the
like. The compositions need not be pigmented and may include corrosion inhibitors and
other additives known to be useful in film-forming coatings.
It will be understood that it is sufficient that the treatment is bacteriostatic or
fungistatic. That is to say, it is sufficient that the treating agent stops colonisation on the
surface rather than kills organisms on a colonised surface.
According to a fourth aspect, the invention provides a method of inhibiting the
formation of a biofilm on a surface susceptible to such formation comprising the steps of
applying a coating of a composition according to the first or second aspects to the surface
and drying the composition or allowing the composition to dry.

In preferred embodiments, the surface is an air conditioning surface, an air
conditioning condenser plate, an air conditioning condenser vent, or may be a susceptible
surface in an operating theatre.
In some embodiments, the composition is baked onto the surface or dried at
elevated temperatures.
According to a fifth aspect, the invention provides a surface treated in accordance
with a composition of the fist or second aspects or according to a method of the fourth
aspect.
Best Modes for Carrying Out the Invention
Various embodiments of the invention will now be more particularly described by
way of example only.
Suitable biocides for use in the invention include, but are not limited to complexes
of PVP or PVP copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol;
orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers.
Examples of formulas:
Formulations were prepared as shown in the following examples

Example 1
Styrene/Acrylic Copolymer Emulsion(50% solids) 60.0%w/w
Water 28.5% w/w
N-Methyl Pyrrolidone 5.0% w/w
PVP/VA S-630 5.0% w/w
Triclosan 1.5% w/w
Example 2
Acrylic Copolymer Emulsion(50% solids) 60.0%w/w
Water 28.5% w/w
N-Methyl Pyrrolidone 5.0% w/w
PVP/VA S-630 5.0% w/w
Triclosan 1.5% w/w
Example 3
Vinyl Acetate/Acrylic Copolymer Emulsion 60.0%w/w
(50% solids)
Water 28.5% w/w
N-Methyl Pyrrolidone 5.0% w/w
PVP/VA S-630 5.0% w/w
Triclosan 1.5% w/w
Example 4
Acrylic Copolymer Emulsion 30.0 - 50.0%w/w
(50% solids)
Epoxy Resin 1001 10.0 - 20.0% w/w
Propylene Glycol Methyl Ether Acetate 10.0 - 20.0% w/w
PVP/VA S630 5.0%w/w
2-Phenoxy Ethanol 2.0-5.0% w/w
Nonyl Phenol Ethoxylate Sulphate Ammonium Salt 2 - 3.0% w/w
Triclosan 1.5% w/w

Example 5
Acrylic copolymer 70% w/w
(50% active solution in ethanol)
PVP/VA S630 5.0%w/w
Triclosan 1.5% w/w
Ethanol 23.5% w/w
PVP/VA S630 is available from ISP corporation.
A cooling coil in the airconditioning system of a large city building situated in
Sydney was thoroughly cleaned and then monitored at intervals over a 12 month period.
A significant growth of biomass was observable on the cooling coil within a month, and
the coil required cleaning at intervals of approximately 3 months. The coil was then again
cleaned and sections of the coil were coated with formulations according to each of
examples 1-3. The coil was inspected at intervals. No biofilm growth was observable
on the coil after 12 months on any of the coated sections.

1. A biostatic composition suitable for application to surfaces and effective to inhibit
biofilm growth for at least 12 months when the surface is moist or wet, the
composition comprising:
a film forming combination of a biocidal complex A-B in which A is a phenolic biocide
and B is selected from the group consisting of polyvinylpyrrolidone polymers,
polyvinylpyrrolidone copolymers and mixtures thereof; and
wherein B is selected so that the biocidal complex A-B is not water soluble but is
dispersed in a water based emulsion by inclusion of a polar solvent or is dispersed in a
solvent based vehicle;
wherein the composition dries to a water insoluble coating when applied to surfaces.
2. A biostatic coating composition according to claim 1 wherein the film forming
combination is selected from acrylic polymer based compositions, methacrylic polymer
based compositions, acrylic copolymer based compositions, methacrylic copolymer
based compositions, vinyl polymer based compositions, vinyl copolymer based
compositions, epoxy resins, epoxy esters, and mixtures thereof.
3. A biostatic coating composition according to claim 1 which has bacteriostatic
properties.
4. A biostatic coating composition according to claim 1 or claim 2 which has
fungistatic properties.
5. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition is an emulsion or latex composition.

6. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition is a polymer or copolymer solution.
7. A biostatic coating composition according to any one of claims 1 to 5 wherein the
film forming coating composition is a polymer or copolymer emulsion.
8. A biostatic coating composition according to claim 7 wherein the film forming
coating composition is a water-based polymer or copolymer emulsion.
9. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition is or includes an acrylic polymer or acrylic
copolymer
10. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition is or includes an acrylic - styrene
copolymer

11. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition is or includes an epoxy or epoxy ester.
12. A biostatic coating composition according to any one of the preceding claims
wherein the film forming coating composition includes a vinyl acetate acrylic copolymer.
13. A biostatic composition according to any one of the preceding claims wherein
the film forming composition is present in an amount of 30 to 80% w/w of the mixture.
14. A biostatic composition according to any one of the preceding claims wherein
the film forming composition is present in an amount of 40 to 70% w/w of the mixture.
15. A biostatic composition according to any one of the preceding claims wherein
the film forming composition is present in an amount of 50 to 60% w/w of the mixture.
16. A biostatic coating composition according to any one of the preceding claims
wherein biocide A is selected from the group consisting of triclosan; diclosan;
dichlorophen; orthophenylphenol; orthobenzylparachlorophenol, cresols, xylols, and
substituted diphenyl ethers.

17. A biostatic coating composition according to any one of the preceding claims
wherein biocide A is a halogenated phenolic biocide.
18. A biostatic coating composition according to any one of the preceding claims
wherein the biocide A is triclosan.

19. A biostatic composition according to any one of the preceding claims wherein
the biocide A is present in an amount of 0.5 to 5% w/w of the mixture.
20. A biostatic composition according to any one of the preceding claims wherein
biocide A is present in an amount of 1 to 2% w/w of the mixture.
21. A biostatic composition according to any one of the preceding claims wherein
biocide A is present in an amount of 1.5% w/w of the mixture.
22. A biostatic coating composition according to any one of the preceding claims
wherein B is polyvinylpyrrolidone.
23. A biostatic coating composition according to any one of the preceding claims
wherein B is polyvinylpyrrolidone/vinyl acetate copolymer
24. A biostatic coating composition according to any one of the preceding claims
wherein B is present in an amount of 2 to 10% of the mixture
25. A biostatic coating composition according to any one of the preceding claims
wherein B is present in an amount of 3 to 8% of the mixture
26. A biostatic coating composition according to any one of the preceding claims
wherein B is present in an amount of about 5% of the mixture

27. A biostatic composition according to any one of the preceding claims containing
solvent in an amount of 20 to 40% of the mixture.
28. A biostatic composition according to claim 27 wherein the solvent is present in
an amount of 25 to 35% of the mixture.
29. A biostatic composition according to claim 27 or 28 wherein the solvent is water.
30. A biostatic composition according to any one of claims 27 to 29 further including
a water soluble polar solvent having a higher boiling point than a solvent vehicle of the
coating composition.
31. A biostatic composition according to claim 30 wherein the high boiling polar
solvent aids dispersion of the complex A-B in a polymer emulsion or latex.
32. A biostatic composition according to claim 30 or 31 wherein the water soluble
polar solvent is selected from N-methyl pyrrolidone, glycol ethers, and combinations
thereof.
33. A biostatic coating formed by drying a film or thin layer of a biostatic coating
composition on a surface,
wherein the biostatic coating composition is suitable for application to surfaces
and is effective to inhibit biofilm growth on the surface when the surface is
moist or wet for at least 12 months;
wherein the composition dries to a water insoluble coating effective to inhibit
biofilm growth on the surface when applied to the surface; and
wherein the composition comprises a film forming combination of a biocidal
complex A-B in which A of the biocidal complex A-B is a phenolic biocide
and B of the biocidal complex A-B is selected from the group consisting of
polyvinylpyrrolidone polymers, polyvinylpyrrolidone
copolymers, and mixtures thereof, and wherein B is selected so that the
biocidal complex A-B is not water soluble but is dispersed in a water
based emulsion by inclusion of a polar solvent or is dispersed in a solvent
based vehicle.
34. A biostatic coating according to claim 33 which is effective to prevent biofilm
growth on its surface for in excess of one year
35. A biostatic coating according to claim 34 which is effective to prevent biofilm
growth on its surface for in excess of three years.
36. A biostatic coating according to any one of claims 33 to 35 when applied to metal

37. A biostatic coating according to any one of claims 33 to 35 when applied to
concrete or a cementitious surface.
38. A biostatic coating according to any one of claims 33 to 35 when applied to a
timber surface.

39. A biostatic coating according to any one of claims 33 to 38 in the form of a
decorative coating.
40. A biostatic coating according to any one of claims 33 to 39 in the form of a paint
to prevent mould growth.
41. A biostatic coating according to any one of claims 33 to 40 in the form of a paint
further including paint ingredients selected from the group consisting of suspension
agents, thixotropic agents, flow and viscosity modifiers, preservatives and the like.
42. A biostatic coating according to any one of claims 33 to 41 in the form of a paint
further including paint ingredients selected from the group consisting of corrosion
inhibitors.
43. A biostatic coating according to any one of claims 33 to 42 in the form of a paint
further including a pigment.
44.
A method of inhibiting the formation of a biofilm on a surface susceptible to such
formation
when the surface is moist or wet, the method comprising the steps of:
applying a coating of a biostatic composition to the surface; and
drying the biostatic composition or allowing the composition to dry,
wherein the biostatic composition of the coating comprises a film forming
combination of a biocidal complex A-B in which A of the biocidal complex
A-B is a phenolic biocide and B of the biocidal complex A-B is selected
from the group consisting of polyvinylpyrrolidone polymers, polyvinylpyrrolidone
copolymers, and mixtures thereof, and wherein B is selected so that the biocidal
complex A-B is not water soluble but is dispersed in a water based emulsion by
inclusion of a polar solvent or is dispersed in a solvent based vehicle, and
wherein the biostatic composition dries to a water insoluble coating
45. A method according to claim 44 wherein the surface is an air conditioning
surface.
46. A method according to claim 44 wherein the surface is an air conditioning
condenser plate.

47. A method according to claim 44 wherein the surface is an air conditioning
condenser vent.
48. A method according to claim 44 wherein the surface is a susceptible surface in
an operating theatre.
49. A method according to any one of claims 44 to 48 wherein the composition is
baked onto the surface or dried at elevated temperatures.
50. A surface treated in accordance with a composition of any one of claims 1 to 32
or according to a method of any one of claims 44 to 49.

Abstract

Biofilm Growth Prevention
A biostatic coating comprising a coating composition which on drying produces an
intrinsically hydrophobic film. The coating composition includes a biocidal complex A-B
in which A is a phenolic biocide and B is selected from polyvinylpyrrolidone ("PVP"),
PVP polymers, PVP copolymers and mixtures thereof. The coating composition for
example is selected from acrylic and methacrylic polymer based compositions, acrylic and
methacrylic copolymer based compositions, vinyl polymer based compositions, vinyl
copolymer based compositions, epoxy resins, epoxy esters, and mixtures thereof. Suitable
biocides for use in the invention include, but are not limited to complexes of PVP or PVP
copolymer with triclosan; diclosan; dichlorophen; orthophenylphenol;
orthobenzylparachlorophenol, cresols, xylols, and substituted diphenyl ethers.

A BIOSTATIC COMPOSITION SUITABLE FOR APPLICATION TO HARD SURFACES TO INHIBIT BIOFILM GROWTH

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