WO1996019921A1

WO1996019921A1 - Iodine biocidal material

Info

Publication number: WO1996019921A1
Application number: PCT/AU1995/000872
Authority: WO
Inventors: Gregor Bruce Yeo Christie; Victor Christov
Original assignee: Commonwealth Scientific And Industrial Research Organisation
Priority date: 1994-12-23
Filing date: 1995-12-22
Publication date: 1996-07-04

Abstract

A biocidally active composition including iodine or a compound or complex thereof and a solublising agent and/or carrier.

Description

IODINE BIOCIDAL MATERIAL

The present invention relates to biocidal compositions and in particular, relates to biocidal compositions including as an active biocidal agent, iodine, its compounds or complexes . The invention also relates to coating compositions, film forming compositions, gels, emulsions, foams, shaped articles and the like having biocidal activity.

Articles formed from polymers are used in many and varied applications. There would be significant benefit in imparting biocidal activity to polymeric articles in certain applications. For example, in the food industry, packaging having a biocidal activity would assist in the control of bacterial, yeast and fungal contamination. Moreover, there are many hospital or medical applications using polymeric articles which would benefit from the use of polymer article having biocidal activity as this would augment the usual infection control used in these areas. Moreover the articles may be used in marine environments as antifouling articles or coatings.

We have found that iodine or its compounds or complexes may be used to impart biocidal activity to compositions, particularly polymer containing compositions. It is an object of the present invention to provide a biocidal compositions that provide an alternative to prior art compositions or that overcome or reduce one or more problems attending the prior art.

By biocidal activity, we mean activity which retards, stops growth of, or kills one or more of yeasts, bacteria, fungi or other microorganisms including viruses, marine microorganisms and foulants.

Accordingly, the present invention provides a composition having biocidal activity, said composition including an active agent selected from iodine or a compound or complex thereof, and a solubilising agent and/or carrier for the active agent. The iodine may be incorporated into the composition by blending iodine or a compound or complex thereof with the solubilising agent and/or carrier. Where the solubilizing agent or carrier is a polymer the iodine may be incorporated by grafting or cross-linking using an iodine containing monomer or oligomer.

Alternatively the carrier may be a substrate and the iodine or compound or complex thereof is applied by applying the iodine or a compound or complex thereof onto the substrate. The term iodine compound includes inorganic iodine compounds such as salts of iodine, for example, potassium iodide, potassium iodate and organic iodine compounds such as iodoform or iodide.

The iodine complex may be any complex that allows free iodine to be liberated in an aqueous medium. The nature of the complexing agent may be selected to provide a predetermined availability of free iodine. The complex may be between iodine and polyvinylpyrrolidone. The complex may be between iodine and starch and/or a starch derivative for example, amylose, amylopectin.

Other iodine complexes may include complexes of iodine with a non-ionic surfactant, ionic surfactant, or a cationic compound, particularly ammonium complexes. Also included are iodine - quaternary ammonium complexes in the presence of anionic surfactants, combinations, modifications and mixtures thereof. The iodine may be solubilized by quaternary ammonium compounds resulting in the formation of complexes which are non-irritating to the skin and mucous membranes. Preferably the iodine or iodine compound or complex is present in an amount of about 0.01 to about 20% of the composition More preferably the active agent is present in an amount of about 0.01 to 5% of the composition.

The solubilising agent or carrier may be any natural or synthetic material.

The solubilising agent or carrier may be a polymer or a polymer precursor such as a monomer or oligomer. The solubilising agent or carrier may also be capable of acting as the complexing agent for iodine.

The composition of the invention may include one or more solvents.

Examples of solvents are water, ethanol, methanol, iso-propanol, chlorinated solvents (e.g., dichloromethane, chloroform) or mixtures thereof. The water stability of the biocidal composition of the invention may be altered by cross-linking. The composition of the invention may be adapted to provide a mechanism for the iodine or compound or complex thereof to contact microorganisms via a controlled release mechanism. For example, the solubilising agent and/or carrier for the active ingredient and/or the degree of cross-linking mechanisms may be selected to provide a slow or sustained release mechanism.

The solubilising agent or carrier may be a water soluble polymer (natural or synthetic) such as Polyvinyl alcohols (fully and partially hydrolysed), amylose, amylopectin or derivatives thereof, starch, polyethyleneoxides, poly n- vinylpyrrolidone (PVP), cellulose such as hydroxyethyl cellulose, natural and synthetic gums polyurethanes, or polyamides etc or mixtures of two or more of said polymers.

A preferred solubilising agent or carrier is polyvinyl pyrrolidone or copolymers of vinyl pyrrolidone.

Preferred are copolymers of vinyl pyrrolidone with one or more monomers selected from the group of vinyl esters, vinyl alcohol, allyl alcohol, ethylene, propylene, butylene, isoprene, butadiene, styrene vinyl ethers, and dimethylaminoethyl methacrylate.

These copolymers may have a molar content of vinyl pyrrolidone between 5% to 95 % and a molar content of the other monomer or monomers of between 95% to 5%. Preferred is a molar content of vinyl pyrrolidone between 10% and 30%.

Also preferred are the poly (N-vinyl pyrrolidone-vinyl ester) copolymers and from these the poly (N-vinyl pyrrolidone-vinyl acetate) copolymers are particularly preferred. The preferred molar ratios of vinyl pyrrolidone units to the units of the other monomer or monomers are within the range of about 90:10 to 10:90, more preferably about 70:30 to 30:70.

The N-vinyl pyrrolidone units may have the formula

and the vinyl ester units correspond to the formula

where R is preferably -CH3, -C2H5, -C3H7 most preferably -CH3

The water stability of the polyvinypyrrolidone polymer of copolymer may be achieved by cross-linking. Cross-linking may be achieved using ring opening mechanisms by the action of bases, particularly strong bases, more particularly sodium metasilicate and trisodium phosphate. This action results in the opening of the pyrrolidone ring and subsequent reaction across different chains.

Other mechanisms for cross-linking to a substrate include the use of polyacids, preferably polyacrylic or tannic acid. These are insoluble in water or alcohol but dissolve in dilute alkali. Methyl vinyl ether/maleic anhydride copolymer will insolubilize PVP when aqueous solutions of polymers are mixed in approximately equal parts at low pH. An increase in pH will solubilize the complex. The polyvinylpyrrolidine polymer of copolymer may be rendered water insoluble. The polyvinlypyrrolidone polymer or copolymer may be cross-linked by irradiation, for example, the influence of actinic light, or by use of diazo compounds and oxidizing agents, such as dichromate also render the PVP coatings insoluble. Heating in air to 150°C will cross-link PVP coatings and strong alkali at

100°C will permanently insolubilize the polymer.

The solubilising agent or carrier may be selected from natural polymers and biopolymers such amylosic material, starches (e.g. amylose and amylopectin), celluloses, proteins such as gelatin, casein, whey etc. Starch is a particularly preferred carrier. The iodine may be incorporated directly into starch or it may be incorporated into the starch material as a complex. The complex may be an iodine-PVP complex. The starch based composition may include a tackifying agent as referred to above. The starch may be made water resistant or water insoluble by cross-linking or by grafting suitable groups to the chain such as phenyl etc. The starch based composition may include one or more polymers such as PVA. The PVA may be present in an amount of about 1- 30%. It has been found that it is possible to produce films of high clarity using starch as the carrier.

Other solubilising agents or carriers can be pectins and other polysaccharides such as carrageenans. Cationically modified polysaccharides with compounds containing amino, imino, ammonium, sulfonium or phosphonium groups all of which carry a positive charge may be used as the solubilising agent or carrier. These modified polysaccharides have a part of or all of the functional hydroxyl groups substituted by residues containing cationic groups such as, but not limited to those listed.

The solubilising agent or carrier may be a anionically modified polysaccharide in which a part or all of the functional hydroxyl groups of the polysaccharide has been substituted by other groups which contain anionic functional groups used. Such groups can include phosphate, phosphonate, sulfate, sulfonate or carboxylate groups in form of their free acids or as salts thereof. Such a salt is preferably an alkali metal or an organic base salt. Such acid groups may be partially esterified.

The average number of hydroxyl groups per anhydroglucose unit which are substituted by a compound containing a group such as an anionic group is called the degree of substitution (DS). The maximum value is 3.0. In this invention the DS level is preferably from about 0.01 to about 2.9, and more preferably, from about 0.01 to about 2.5. Most preferred is a value from about 0.05 to about 1.0. Further possible substituents are hydroxy alkyl, preferably hydroxyethyl or hydroxypropyl and/or alkyl ether preferably methyl ether or ethyl ether. Preferred are alkyl ethers. The solubilising agent or carrier may be modifications of above, such as hydroxypropylated starch, hydroxypropyl methyl cellulose etc. The solubilising agent or carrier may be selected from lipids and phospholipids such as lecithin.

The solubilising agent or carrier may be a water soluble, partially water soluble or water insoluble synthetic polymer. The synthetic polymer may be selected from rubbers or polymers manufactured by condensation or addition process. This includes in-situ polymerisation and reactive extrusion processing. Examples include polyolefms such as linear low density polyethylene, elastomers such as polyurethane. Other examples include components selected from groups consisting of vinyl polymers, polystyrenes, polyacrylonitriles, polyacrylates, polymethacrylates, polyacetals, thermoplastic condensates, polyarylethers, thermoplastic polyimides, polyhydroxybutyrates, polyvinyl chloride, polyamides, poly propylenes, polyvinylcarbazols, polyacrylic acid esters, polymethacrylic acid esters, ethylene/vinyl acetate copolymers (EVA), ethylene/vinyl alcohol- copolymers (EVAL), ethylene/acrylic acid - copolymers (EAA), ethylene/methyl acrylate copolymers (EMA), acrylonitrile-butadiene-styrene-copolymers (ABS), polycarbonates, polycaprolactones, copolymers of PVC, styrene/acrylonitrile - copolymers (SAN), water insoluble or crystallizable polyalkylene oxides, alkylene/maleic anhydride copolymers, partially hydrolyzed polyacrylates or poly methacrylate, partially hydrolyzed copolymers of acrylates methacrylates, acrylic acid esters/acrylonitrile copolymers and hydrolysates thereof, acrylamide/acrylonitrile copolymers, block copolymers of amide-ethers, amide esters, block copolymers of urethane ethers, urethane-esters or fluoropolymers.

Thermosetting polymers such as epoxy, fluoroplastics, phenolics, polyurethanes, formaldehyde resin systems, melamine, polyesters and combinations and mixtures thereof may be used as the solubilising agent and/or carrier.

The solubilising agent and/or carrier may be an inorganic polymer. The inorganic polymer may be an organic silicone or associated polymer based material or an aminoalkylalkoxysilane such as aminopropyltriethyoxysilane.

The solubilising agent and/or carrier may be a polymerisable organic monomer. Monomers such as vinyl pyrrolidone, styrene, or any other compound that can be polymerised by coordination, radical, cationic or amionic polymerisation mechanism may be used as the solubilising agent and/or carrier

Polymers with inorganic components are also included in the scope of this invention. These may include materials such as Siθ2, titanium dioxide, calcium carbonate, metal ions such as sodium, potassium, magnesium and zinc. An example of a preferred level is about 2.8% sodium or about 17 sodium atoms per 1000 carbon atoms. In all the above situations copolymers, combinations and mixtures thereof are included in this invention.

The composition of the invention may be in the form of a gel, foam, emulsion or colloidal system. The gels may be capable of absorption of large amounts of water. An example being the formation of a gel with polyvinylpyrrolidone and/or active ingredients. The gel may be formed by heating the polyvinylpyrrolidone, for example, at about 90°C for about 30 minutes. These gels are not thermoreversible and are substantially insoluble in large amounts of water or salt solution. The composition of the invention may include a gelling agent. A preferred gelling agent is ammonium persulfate. The more alkaline sodium phosphates may be used as the gelling agent. When dried under mild conditions, PVP based gels retain their uniform structure and capacity to swell again by absorption of large amounts of water.

The composition of the invention may be in the form of a coating or a film forming composition. The coating compositions or film coating forming composition may be water-based or solvent based.

The coating or film forming composition may include conventional additives such as tackif ing agents, particularly glycerine mono oleate (GMO), more particularly, polybutene or polyisobutene (PIB). Preferred levels of the tackifying agent are between 0.01% and 40%, most preferred between 1 and 5%. Combinations, modifications and mixtures with other additives disclosed hereunder such as starch, gelatin etc are also covered by this invention. The coating composition may include a pigment and/or binder. The coating or film forming composition finds application in marine antifouling. The coating or film forming composition may be applied to secondary structures such as the hulls of ships and boats. The coating composition of the invention may be applied to aquacultural nets.

The coating or film forming composition may be suitable for application to a substrate by spraying, painting, roll coating or used to form a preformed laminate or sheet which may then be applied by lamination or sheet application.

Radiation treatment of the coating formed is also within the scope of this invention. Examples may include infra-red, ultra-violet, gamma radiation. Combinations, mixtures of the above chemical and radiation treatments are also included.

The invention also provides a method of treating a substrate, the method including coating or covering the substrate with a coating or film forming composition in accordance with the invention.

The substrate to which the coating composition may be applied can be, but is not limited to: metal or treated metal, for example aluminium, anodized aluminium, steel etc wood polymeric materials (natural and Synthetic), for example, plastics such as polyethylene, rubber glass/treated paper textiles treated, for example natural and/or synthetic fibres such as wool, PET, silk, nylon, HDPE etc.

In yet a further aspect, the present invention provides an article having biocidal activity, the article being treated at least in part with iodine or a compound or complex of iodine.

The article of the invention may be formed at least in part from a composition in accordance with the invention.

The article may be a shaped article. The shaped article may be in the form of a film, sheet, fibre, foam, package or container (for example a bottle), pipe, rod, packaging material, aquacultural net, sack, bag, pharmaceutical, medical and personal health packaging product optical device (eg. a lens) etc. The present invention has particular application to food packaging.

Preferably the shaped article is at least in part formed from a polymer. Iodine or the iodine compound or complex may be incorporated into the polymer. Alternatively the active agent may be applied as a coating to a least a portion of the surface(s) of the article. The substrate may be a controlled permeability film, for example, the film described in International application PCT/AU92/00344 the whole disclosure of which is incorporated herein by reference. The substrate may be a condensation absorbing material, for example, the water absorbing material, particularly in the form of a film, as described in applicant's co-pending application titled "Packing Material" (Our Ref: IRN 385284) filed 23 December, 1994.

The article of the invention may be formed by foaming, filming, compression moulding, injection moulding, blow moulding, extruding, co- extruding, vacuum forming, thermoforming and combinations thereof.

Iodine or its compounds or complexes may be incorporated into a polymer before forming the final article, for example, before extrusion into blown film, sheet or fibre. The invention in a further aspect provides a polymeric film suitable for food packaging said film having been treated with iodine or an iodine compound or complex as described above.

The film may have a thickness in the range of about 0.5 to 100 μ, more preferably 1 to 40 μ. A film thickness of 1 to 30 μ is particularly preferred. The film of the invention may be supported on a substrate. The substrate may be a polymer film or sheet or a plurality of polymer films or sheets.

In a further aspect the invention provides produce packaged in an article in accordance with the present invention. The produce may be meat, fruit, vegetable or seafood or other foodstuff. We also found that articles formed of a composition in accordance with the invention may be prepared so that they change colour in the presence of oxygen, The change in colour in the presence of oxygen is believed to be due to the formation of a complex between iodine present in the composition and absorbed oxygen. The complexing agent for iodine present in the composition is preferably starch as this has been found to provide a significant change in colour intensity in the presence of oxygen. This property of a composition of the invention may be used to practical effect in providing articles which indicate the presence or absence of oxygen or which can be used to deplete oxygen from the environment adjcent the surface of the article. In one embodiment the invention provides an enclosure such as a container, bag or package at least part of the inner surface of which includes a composition of the invention. The composition may be applied to the inner surface or the inner surface may be formed of the composition. The enclosure may be adapted to provide an air tight seal so that the presence of oxygen on the interior of the enclosure is indicated when the composition of the invention is a specific colour or colour intesity. A colour change may be reversible so that during absorption of oxygen the colour changes, for example from clear and colourless to a specific colour or from a light colour to a more intense colour and this change is at least partly reversible as the oxygen concentration is depleted. The composition of the invention may include catalysts or complexing agents which enhance the removal of oxygen. Shaped articles, in accordance with the invention preferably exhibit effective biocidal activity against bacteria, molds, yeasts, protozoa, viruses, nematodes, worm larvae, insects and other fungi which cause pathological conditions in plants. The invention finds suitable application for agricultural mulch film and greenhouse film where spread of infection to plants is a problem. The invention is well suited to marine and aquatic applications, such as aquacultural nets. Iodine is found naturally occurring in the marine environment and is non toxic to fish.

The composition of the invention may include one or more materials selected from the group consisting of fillers, lubricants, mold release agents, absorbing agents plasticizers, foaming agents, adjuvants, stabilizers, cross-linking agent extenders, chemical modifiers, flow accelerators, coloring agents pigments, Theological modifiers and combinations and mixtures thereof. Examples include glycerol, water, ethanol, corn zein, lecithin cellulose acetate, carboxymethyl cellulose, cellulose acetate propionate, arylsulfonamide-formaldehyde, ammonium peroxydisulfate, diazo compounds, dichromates, sodium metasilicate, trisodium phosphate, polyethylene glycol, urea, dimethyl phthalate, sorbitol, glycerol monoricinoleate, dibutyl tartarate, oleyl alcohol, pentaerythritol, dipentaerythritol, trimethylol propene, or combinations, mixtures thereof.

As mentioned above, the present invention also has industrial applications as well as applications in hospital and medical environments where there is a need to maintain infection control. The properties of iodine make it ideal for use in many applications, particularly in view of its lack of toxicity. Iodine is and a trace element essential to animal and vegetable life. Iodine and its compounds occur naturally in the marine environment and therefore can be used in application in this context without the fear of creating pollution. It is also an approved food additive (for example, salt- iodized) and is contained in injestable medicine.

In order that the invention may be more readily understood, we provide the following non-limiting embodiments.

Example 1:

This example is based on the use of PVP and iodine. PVP itself is a water- soluble polymer physiologically acceptable to humans one of the advantages of poly n-vinylpyrrolidone in combination with iodine is the extremely low toxicity. Among the accepted uses of PVP are: using it as a wine clarifying agent, and water solutions with PVP can be used as a blood plasma substitute (artificial blood - German patent 737,663; 738,753 first report).

15% w/v Poly-N-Vinyl-2-Pyrrolidinone + % w/v Glycerol + 0.2 - 5.0% w/v (K, Na) Iodide were dissolved in ethanol or 75% v/v ethanol/25% water mixture with stirring.

The mixture was spread over PET film (20 micron thickness) and dried in air @ 25°C for 1.0 hour.

The PVP film was crosslinked @ 190°C for 4 hours or 220 for 2 hours, in air. The thickness of crosslinked PVP film containing Iodide was about 15-20 micron.

Conclusion

Both the 15 Kl and 5% Nal films caused a zone of inhibition to be formed on both Staph. Epidermidis and E. Coli indicating that the films are biostatic. A biostatic effect is taken to occur if the inhibiting substance is removed the colonies will continue to grow over the area where the substance was initially present.

A biocidal effect is taken to occur if the colonies will not grow over the area where the substance was present.

To establish the biocidal activity of the film it may be placed in a broth.

Once the micro-organism (Bacterium) has been inhibited killed, a loop full of the broth can be plated out on nutrient agar. If this does not grow on the nutrient agar then the film can be said to be biocidal. If the loop full of broth produces new colonies then the film is said to be biostatic.

Also the Minimum Inhibitory Concentration can be determined. This is done by producing a series of plates with decreasing bacterium concentration (using dilution). The dilution where inhibition no longer occurs is said to be the MIC.

Biocidal / Biostatic Testing

Samples 1) PET Film

2) 15% w/v PVP + 5% w/v Glycerol in Ethanol on PET Film.

3) 15% w/v PVP + 5% w/v Glycerol + 1% w/v Kl in Ethanol on PET Film.

4) 15% w/v PVP + 5% w/v Glycerol + 5% w/v Nal in Ethanol on PET Film.

(Samples 2-4 crosslinked @ 190°C for 4 hours in air)

Biostatic Test Samples 1 and 2 showed no biostatic properties properties with bacteria Staphylococcus epidermis and Escherisia coli. samples 3 and 4 (with iodide) showed biostatic properties with bacteria Staphylococcus epidermidis and Escherisia coli.

It has been shown that PVP acts in a manner similar to plasma protein in combining with iodine (J. Int. Coll. Surgeons, June 1956, p728). A small fraction (less than 1 %) of the iodine is converted directly into inorganic iodide. The reaction occurs at the ends of the PVP molecules, where an acid environment prevails. The amount of inorganic iodide formed is determined by the number of free end groups and thereby by the molecular weight of any given PVP sample. About 30% of the iodine is converted into organic iodide (corresponding to protein bound iodine). The remainder of the iodine exists as free elemental iodine. The free iodine is made soluble by the organic iodide. The free iodine is in solution in the water. Also within the scope of this invention is the formation of a colloidal system such as a phase system. A preferred formulation is 10gm of available iodine per 100 gm of PVP.

Most preferred is where 85% is PVP, 10% available iodine and 5% iodide ion.

Another advantage of shaped articles produced with this system is that they possess the advantages of free iodine without the disadvantage of staining as do iodine solutions. This is important for food packaging. Slight discoloration occurs which can be removed by wiping or washing.

In a 1% solution of PVP in water the solubility of iodine is increased 17-fold of that in water.

Example 2: Biocidal Shaped articles and or films, fibers, foams etc are formed by complexing iodine with a nonionic surfactants such as polyethyleneglycol mono(nonylphenyl)ether. Complexes such as these function by rapidly liberating free iodine in say water solutions, structure is given below:

Example 3:

Shaped articles, films fibers etc formed with P-tolydiiodomethyl sulfane as the active substance viz

Example 4:

Shaped articles, films, fibers etc. are formed with P- chlorophenyldiiodomethyl sulfane as the active substance viz

Shaped articles, films, fibers etc may be formed using starch and its derivatives with PVP-I to produce extruded articles wherein the further processing may comprise foaming, filming, compression moulding, injection moulding, blow molding, extruding, co-extruding, vacuum forming, thermoforming and combinations thereof.

Example 5:

As per example 4 where the formulation includes a water soluble polymer, preferably polyvinyl alcohol, more preferably fully hydrolized PVOH such as Dupont Elvanol HV.

Microbiological Laboratory tests:

Microbiological activity was investigated by testing the following examples:

Example 6: PET film

Example 7: 15% PVP on PET film

Example 8: 15% PVP + 1% Kl on PET film

Example 9: 15% PVP + 5% Nal on PET film Bacterial used were both gram-negative and gram-positive more specifically staphylococins. Epidermidis (g+ve) and Eschericia. coli (E. Coli) (g- ve).

Microbiological Lab Tests Methods:

1. Initially the solid nutrient Agar was melted and sterilized in the Autoclave.

2. The nutrient Agar was poured (from the McCarthy Bottles) into the plates and allowed to dry for 5 minutes by allowing to stand

3. The Agar was then dried in a warm room (about 37°C) for 20 minutes.

4. A lawn of bacterium was prepared using cotton buds. These were then allowed to set by drying in the warm room for about 10 minutes. The plates were split into two to allow the testing of the two films using the one bacterium.

5. Using sterile gloves and scissors, pieces of films were cut out and placed on the lawned agar.

6. The plates were then incubated overnight in the 37°C warm room.

Results. Example 6 - PET FILM ONLY

Colonies of bacterium have grown right up to the edge of the film. No zone of inhibition was observed around the films using either bacterium.

Microbiological Results, Example 7 - 15% PVP on PET FILM

No zone of inhibition was observed around the film. Colonies have grown right up to the edge of the film.

Microbiological Results. Example 8 - 15% PVP - 5% Nal on PET FILM A zone of inhibition was observed around the film of 2-3mm. This was observed for both E. Coli and Staph. Epidermidis. This shows the film has biostatic properties. The term "biostatic material" indicates that while the film is over the cultures, growth is inhibited within a given perimeter of the film. If the film is removed colonies will continue to grow over the area where the film was located.

Shaped articles with Bisglycine hydroiodide - Iodine (Hθ2CCH2NH2)2.2Hl.l2; 2,3,4,5-tetraiodopyrrole; dithymol diiodide; bis(p- chlorophenyl) iodonium chloride, aluminium hexaurea sulfate triiodide and aluminium hexaurea dinitrate triiodide, combinations, mixtures, chemical modification emulsions, colloidal systems, whether or not they be dispersed in ionic or nonionic surfactants or combinations with the previously described components are within the scope of this invention.

Iodide ion can be added to increase the solubility of iodine in water. In the marine environment iodide species are present enabling an exchange equilibrium to exist. The exploitation of this marine environment to absorb, or absorb and release the active ingredients is also covered by the scope of this invention. The ratio of iodine and iodide is dependant upon the pH and the concentration of iodide. The pH of sea water ranges between 7.7 and 8.3 and has an elemental iodine concentration of 60mg/L. This invention covers alkaline, acidic and neutral environments, and other environments where iodine species are present.

PVP has detoxifying properties of its own which offer a novel approach to the reduction of toxicity and sensitivity problems inherent in many compounds. It binds various toxins, viruses, dyes and other chemicals. It permits the use of substances for human use that would otherwise be too toxic, irritating or skin fatiguing [Ref: General aniline and Film Corporation, 140 West 51 Street, NY, USA]. This is an important property applicable to this invention particularly with food packaging applications. More particularly when used with iodine (which has FDA GRAS status), enabling high levels of active ingredients to be used, but masked from the food. With PVP, the oral toxicity of iodine to mammals is drastically reduced [General Analine + Film Corporation, New York, USA].

Other factors within the scope of this invention are pH changes on the surface of the shaped articles. This may be as a result of the release of active ingredients in moist environments. This pH change may cause inhibiting effects to organisms that are pH sensitive. Example would be the release of SO2 producing sulfurous acid on the surface.

Example 10:

ZONE 1 ZΩN 2 ZΩNE2 ZONE 4

110 138 120 118 (Pressure 50 BAR)

(feed) ((ddiiee)) A film of excellent clarity was produced.

Example 11 :

A composition was prepared from 30% amylose, about 10% water, 1% potassium iodide, polyvinyl alcohol and glycerol was used as a plasticiser. The composition was preblended and placed into a twin screw extruder from which rods were extruded at a temperature of 110°C. The rods produced were stored in an air tight container and were transparent and either colourless or a faint yellow colour. On exposure to air the rods developed a bright orange colour.

Biodegradation was found to be delayed in starch based formulations compounded with an iodine species. This has applications in biodegradeable packaging and agricultural mulch film. Biodegradation was measured using the Sturm test.

Example 12:

53% A939 hydroxypropylated high amylose starch 17% H₂0

16% glycerine

10 % PVOH

3% Ferric Sulphate

1 % Kl When compared to a formulation in accordance with the above but without the iodine species being present, it was found that the incorporation of iodine delayes the biodegradation of the film.

Starch films manufactured using potassium iodide are of exceptional clarity. After prolonged exposure to air it is possible for the film to change colour to yellow to dark brown or black. This phenonenon can serve as an indicator for oxygen exposure over time in packaging. Other colours are possible depending on the species of ions present eg. Fe, Cu etc.

Biocidal Films

Further films containing iodine were prepared (see Table 1) using the compounding temperature profiles given in Tablel . The aim was to determine:

(1) Processability with iodine

(2) Identify suitable iodine species (3) Effect of amylose/amylopectin ratio

(4) Obtain an indication of levels of iodine species needed.

Conclusions

(1) Processability using potassium iodide is excellent. The Kl is an excellent plasticiser for starch. At levels of 15% Kl the starch polymer is rubber like in feel. High throughput possible through the extruder.

(2) The nature of the iodine species is critical for obtaining desired effects. When using Kl the color of the extrudate is almost identical to compounded A939 hydroxypropylated starch with a slight tint of yellow depending on level of Kl. Because there is no coloring of the starch with the iodine, indications are that iodine is present as the iodine (I). When exposed to oxygen the iodide is oxidised to l₂ causing a color change to dark red/black. It should be possible to control colour using starches of differing amylose levels (blues, purples, reds etc.) results in materials of different colors eg. fiber, film, lens etc. starches of varying amylose/amylopectin levels. This phenomenom may be utilised in the manufacture of films that indicate the presence of oxygen, and possibly scavenge 0₂ in barrier type packaging. The film's biocidal property would increase as the level of 0₂ increases as a result of time.

The color changes associated with amylose/iodine may be a result of (but not limited to) the formation of l₃ ^' and higher species. The formation of the triodide results according to:

31^' = l₃- + 2e l_{2 +} 2e = 2f

l₂ + 31^" = l₃ ^" + 21^"

The amylopectin has shorter amylose chains which are capable of binding iodine, and so only shorter polyiodine species may be stabilised.

A means of getting coloration (l₃ ^~) is to have both l₂ and I^" species present. l₂ is freely soluble in I^" and so a solution may be prepared with both species present and compounded into starch.

Another method that can be used to produce the l₃ ^" species, is to oxidise the I^' to form l₂. This may be done by using, including an oxidising species such as Fe³⁺, Cu²⁺ etc. To test this, a starch formulation was produced containing Kl and iron sulphate (Fe (S0₄) H₂0), and then compounded on the extruder. The result was an extrudate of intense purple color, indicating that the iodine complexed into the amylose (A939-hydroxypropylated) helix. Optimum concentrations may be determined by experiment. When l₂ was compounded into the starch, there was no sign of iodine complexing, ie. there were no color changes. This is also explained due to the lack of l₃ ^" (or greater) being formed. The l₂ did compound into the starch and did not sublime. This was proven by complexing the pellets with copper giving black pellets due to the Cul formed. IABLE L

SAMPLE FORMULATION COMPOUNDING TEMPERATURE PROFILE

42% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 15% Potassium iodide

47% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 10% Potassium iodide

52% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 5% Potassium iodide

56.5% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 0.5% Potassium iodide

56.9% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 0.1% Potassium iodide

56.99% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 130 120 10% PVOH HV 0.1% Potassium iodide

56.924% A939 Starch

17% Water

16% Glycerine 80 110 130 135 140 140 145 145 130 120

10% PVOH HV

0.076% Iodine (in 20g ethanol)

56.924% Mazaca 3401 X Starch

17% Water

16% Glycerine 80 110 130 135 140 140 145 145 130 120

10% PVOH HV

0.076% Iodine (in 200g ethanol) TABLE 1 continued

SAMPLE FORMULATION COMPOUNDING TEMPERATURE PROFILE

55% A939 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 110 10% PVOH HV 2% Kl

56.924% Gelose 50 Starch

17% Water

16% Glycerine 80 110 130 135 140 140 145 145 130 120

10% PVOH HV

0.076% Iodine (in 200 g ethanol)

68.8% A939 Starch 10.7% Water 10.1 % Glycerine 80 110 130 135 140 140 145 145 120 120 10.0% PVOH HV 0.3% Ferric sulphate 0.1% Potassium iodide

66.7% A939 Starch 10.7% Water 10.1% Glycerine 80 110 130 135 140 140 145 145 120 120 10.0% PVOH HV 1.0% Ferric sulphate 0.6% Potassium iodide

53% A939 Starch 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 120 10% PVOH HV 3% Ferric sulphate 1 % Potassium iodide

57.00% A939 Starch 17.00% Water 12.08% Glycerine 10.00% PVOH HV 80 110 130 135 140 140 145 145 120 110 2.00% Kl

1.50% Cabot Acarb 670 0.30% Silica powder 0.12% Crodamide ER

56.5% Wheaten Cornflour 17.0% Water 16.0% Glycerine 80 110 130 135 140 140 145 145 120 110 10.0% PVOH HV 0.5% Kl TABLE 1 continued

SAMPLE FORMULATION COMPOUNDING TEMPERATURE PROFILE

55% Wheaten Cornflour 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 110 10% PVOH HV 2% Kl

52% Wheaten Cornflour 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 110 10% PVOH HV 5% Kl

56.5 UMS 3417C (27% Amylose) 17.0% Water 16.0% Glycerine 80 110 130 135 140 140 145 145 120 105 10.0% PVOH HV 0.5 Kl

55% UMS 3417C (27% Amylose) 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 105 10% PVOH HV 2% Kl

52% UMS 3417C (27% Amylose) 17% Water 16% Glycerine 80 110 130 135 140 140 145 145 120 105 10% PVOH HV 5% Kl

Starches sourced from STARCH AUSTRALIASIA LIMITED for this patent.

Claims

CLAIMS:

1. A composition having biocidal activity, the composition including an active agent selected from iodine or a compound or complex thereof, and a solubilising agent and/or carrier for the active agent.

2. A composition according to claim 1, wherein the solubilising agent or carrier is capable of acting as a complexing agent for iodine.

3. A composition according to claim 1, wherein the active agent is selected from a salt of iodine or an organic iodine compound.

4. A composition according to claim 3, wherein the iodine compound is an iodine containing monomer, oligomer or polymer.

5. A composition according to claim 4, wherein the solubilising agent or carrier is a polymer and the iodine containing monomer or oligomer is incorporated by grafting or crosslinking.

6. A composition according to claim 3, wherein the iodine salt is selected from the group potassium iodide or potassium iodate.

7. A composition according to claim 2, wherein the active agent is selected from bisglycine hydroiodide, 2,3,4,5 tetraiodopyrrole, dithymol diiodide, bis(p- chlorophenyl) iodonium chloride, aluminium hexaurea sulfate triiodide, aluminium hexaurea dinitrite triiodide and combinations or mixtures of one or more thereof.

8. A composition in accordance with any one of the preceding claims, wherein the composition is in the form of an emulsion, dispersion or colloidal system.

9. A composition according to any one of the preceding claims, wherein the active compound is an iodine complex which liberates free iodine species.

10. A composition according to claim 1 , wherein the iodine complex is selected from an iodine complex with polyvinylpyrrolidone, a complex with a copolymer of vinyl pyrollidone and one or more other monomers, a complex with a starch or starch derivative, a complex with a non-ionic or ionic surfactant or a complex with a cationic compound.

11. A composition according to claim 10, wherein the iodine complex is an iodine ammonium complex.

12. A composition according to any one of the preceding claims, wherein the active agent is present in an amount of about 0.01 1 o 15% of the composition.

13. A composition according to claim 12, wherein the active agent is present in an amount of about 0.01 to 5% of the composition.

14. A composition according to any one of the preceding claims, wherein the solubilising agent or carrier is a water soluble, partially water soluble or water insoluble polymer or polymer precursor.

15. A composition according to claim 14, wherein the solubilising agent or carrier is a natural or synthetic polymer.

16. A composition according to claim 15, wherein the solubilising agent or carrier is selected from the group polyvinyl alcohols, starch or a derivative thereof, amylose or a derivative thereof, amylopectin or a derivative thereof, polyethylene oxide, polyvinylpyrrolidone, copolymers of vinyl pyrollidone, cellulose, natural or synthetic gums, polyurethanes, proteins, polysaccharides, modified polysaccharide or polyamides or mixtures of one or more thereof.

17. A composition according to claim 16, wherein the solubilising agent or carrier is selected from copolymers of vinyl pyrrolidone with one or more monomers selected from vinyl esters, vinyl alcohol, allyl alcohol, ethylene, propylene, butylene, isoprene, butadiene, styrene vinyl ethers, an dimethylaminoethyl methacrylate.

18. A composition according to claim 17, wherein the copolymers have a molar vinylpyrrolidone content of between about 5-95%.

19. A composition according to claim 18, wherein the vinylpyrrolidone molar content is between about 10 and 30%.

20. A composition according to any one of claims 16 to 19, wherein the water stability of the vinylpyrrolidone polymer or copolymer is improved by cross-linking.

21. A composition according to claim 20, wherein the polymer or copolymer is rendered water insoluble by cross-linking.

22. A composition according to claim 16, wherein the solubilising agent or carrier is selected from starch or a derivative thereof, amylose or a derivative thereof, or amylopectin or a derivative thereof.

23. A composition to claim 22, wherein the solubilising agent or carrier is a starch.

24. A composition to claim 23, further including a water-soluble polymer, especially polyvinyl alcohol.

25. A composition to claim 24, wherein the water-soluble polymer is present in an amount of about 1-30%.

26. A composition according to any one of the preceding claims, further including one or more antimicrobial agent(s).

27. A composition according to any one of the preceding claims, further including a solvent.

28. A composition according to claim 27, wherein the solvent is selected from water, ethanol, methanol, iso-propanol, or a chlorinated solvent.

29. A composition in accordance with any one of the preceding claims, further including one or more of a filler, lubricant, mould release agent, absorbing agent, plasticiser, foaming agent, adjuvant, stabiliser, cross-linking agent, extender, cross-linking agent, chemical modifier, flow accelerator, coloring agent, pigment, Theological modifier.

30. A composition according to claim 29, including one or more of glycerol, water, ethanol, corn zein, lecithin, cellulose acetate, carboxymethyl cellulose, cellulose acetate propionate, arylsulfonamide-formaldehyde, ammonium peroxydisulfate, diazo compounds, dichromates, sodium metasilicate, trisodium phosphate, polyethylene glycol, urea, dimethyl phthalate, sorbitol monoricinoleate, dibutyl tartrate, oleyl alcohol, pentaerythritol, dipentaerythritol, trimethylol propane.

31. A composition according to any one of the preceding claims in the form of a curable composition.

32. A composition according to any one of the preceding claims, wherein the active agent is in a controlled release form.

33. A composition according to any one of the preceding claims wherein the composition is the form of a gel or foam.

34. A composition of claim 33, wherein the gel is formed from polyvinyl pyrrolidone.

35. A composition according to any one of the preceding claims, wherein the composition is in the form of a film forming or coating composition.

36. A coating composition according to claim 35 in a form suitable for application to a substrate by spraying, painting, dipping, casting, laminating or roll coating.

37. A coating composition according to claim 35 or claim 36, in the form of a preformed laminate or sheet.

38. A composition according to any one of claims 35 to 37, further including a tackifying agent.

39. A composition according to claim 38, wherein the tackifying agent is selected from glycerine monooleate, polybutene or polyisobutene or mixtures thereof.

40. A biocidal film, the film being formed from a composition in accordance with any one of the preceding claims.

41. A film according to claim 40, wherein the film has a film thickness in the range of about 0.5 to 100μm.

42. A film according to claim 41 , wherein the film has a thickness of about 1 to 40μm.

43. A film according to claim 42, wherein the film has a thickness of about 1 to 30μm.

44. A film according to any one of claims 35 to 43, wherein the film is supported on a substrate.

45. A film according to claim 44, wherein the substrate is a controlled permeability layer.

46. A multilayer laminate including at least two layers , at least one of the layers being formed from a composition in accordance with any one of claims 1 to

37.

47. A shaped article, the shaped article being formed at least in part from a composition of claims 1 to 34.

48. An article according to claim 47, in the form of a film, sheet, fibre, foam, container, pipe, rod, packaging material, optical device, aquacultural net, sack or bag.

49. An article according to claim 47, in the form of pharmaceutical, medical or personal health packaging product.

50. A fibre formed at least in part from a composition in accordance with any one of claims 11 to 39.

51. An enclosure for storage of food, produce or the like, the enclosure or surface thereof being formed at least in part from a composition in accordance with any one of claims 1 to 35.

52. An enclosure according to claim 47, wherein the active component is complexed with starch.

53. An enclosure according to claim 47 or 48, wherein the biocidal composition further includes a catalyst or complexing agent that enhances the removal of oxygen.

54. An enclosure according to claim 48, wherein the enclosure is a container, bag or package.