The present invention relates to anti-fouling compositions and the use thereof to coat solid surfaces.

Anti-fouling coatings are useful when applied to surfaces which come into contact with aqueous media containing organisms which can attach themselves to such surfaces. Thus, anti-fouling coatings have become popular in marine environments to prevent animal and vegetable organisms such as algae and barnacles from attaching themselves to solid surfaces such as ship hulls. The presence of such organisms significantly increases the drag on ships thereby increasing the energy requirements to propel the ship through the water. The growth of micro-organisms in circulating water systems such as that found in cooling towers, recreational waters and industrial cutting fluids can also create problems when such micro-organisms attach themselves to surfaces, especially the inner walls of pipes and heat exchangers which restricts the flow of water and reduces the efficiency of heat exchangers. Furthermore, the attachment of such micro-organisms can result in the growth of symbiotic colonies of bacteria, fungi and yeasts which can generate an extemal protective envelope. The presence of such colonies attached to pipes etc not only reduces the water-flow but can also act as a reservoir of micro¬ organisms especially where a protective envelope is present. Such an envelope can prevent the micro-organisms within the protective biosphere from coming into contact with anti-microbial active agents. This can result in unhygienic water which is a particular problem with recreational circulating water systems such as swimming pools, spas and hot tubs.

Micro-organisms are also found on solid surfaces in the food and health-care industries and can result in unhygienic conditions, especially in the preparation and packaging of foodstuffs.

One of the more successful ways of preventing marine organisms from attaching to solid surfaces such as ship hulls is to coat the surface with a self-polishing anti-fouling paint, such as that disclosed in WO 91/09915. This discloses an anti-fouling coating composition comprising a marine biocide and a binder which is a hydrolysable film-forming seawater-erodible polymer, characterised in that the polymer contains sulphonic acid groups in quaternary ammonium salt form. These polymers have limitations and are not particularly effective against micro-organisms, especially those

present in circulating water systems. We have now found an anti-fouling coating polymer which exhibits advantage over that described in WO 91/09915 and which is particularly effective against those micro-organisms which colonise circulating water systems and especially those which generate a protective envelope. The polymer also exhibits a long-lasting anti-microbial effect when applied to solid surfaces typically used for food preparation and packaging.

According to the invention there is provided a water-erodible organic polymer bearing anionic salt groups at least a proportion of which have as counter ions a biologically active heterocyclic cation having a delocalised positive charge. There is also provided a composition for providing a water-erodible polymer- coating on a surface wherein said composition comprises a binder polymer as defined supra and an organic liquid. The coating composition may optionally contain a corrosion inhibitor, pigment, further microbiologically active compound or other adjuvant.

The term water-erodible polymer coating refers to a coating where the outer layer of the coating is removed on contact with water and is further explained hereinafter.

The anionic groups are, for example, derived from one or more of phosphoric, phosphonic and especially carboxylic and sulphonic acid groups.

Preferably the heterocyclic ring of the heterocyclic cation contains two or more hetero atoms especially two or more nitrogen atoms. The heterocyclic ring preferably contains 5 atoms. Examples of such heterocyclic rings are pyrazolyl, triazolyl and especially imidazolyl rings.

The heterocyclic cation may contain only the one heterocyclic ring but preferably contains two or more heterocyclic rings. More preferably the cation contains two heterocyclic rings. A cation containing two or more heterocyclic rings may form a salt linkage between each cationic ring and an anionic group in the same or different polymer chains. It is preferred, however, that at least one cationic ring of the cation containing two or more heterocyclic rings does not form a salt linkage with an anionic group of the polymer chain. Thus, for example, when the cation contains two heterocyclic rings it preferably forms only the one salt linkage with an anionic group in the polymer chain.

When the cation contains two or more heterocyclic rings, the rings are preferably the same.

When the heterocyclic cation is a an imidazolium cation having one ring it is preferably a cation of Formula 1

wherein

R ¹ is C^^-alkyl or aralkyl;

R ² is hydrogen or C^-alkyl; R ³ is C^-alky! or aralkyl; and

R ⁴ and R ⁵ are each, independently, hydrogen or C^-alkyl or R ⁴ and R ⁵ together with the carbon atoms to which they are attached form a phenyl ring.

The alkyl groups represented by R ¹ and R ³ may be linear or branched but are preferably linear. It is also preferred that R ¹ and R ³ are each, independently, alkyl containing at least 6 carbon atoms and preferably at least 8 carbon atoms. Preferably R and R ³ each, independently, contain less than 18, more preferably less than 16 and especially less than 12 carbon atoms.

When R or R ³ is aralkyl, it is preferably benzyl or 2-phenylethyl. Preferably R ¹ is the same as R ³ .

It is preferred that both R ⁴ and R ⁵ are hydrogen.

It is also preferred that R ² is hydrogen, ethyl and especially methyl.

The preparation of suitable imidazolium compounds for providing some of the cations of Formula 1 are described in GB 1,503,077. Useful effects have been obtained with a 1,3-di-n-decyl-2-methyl-imidazolium cation.

Where the heterocyclic cation is an imidazolium cation containing two or more heterocyclic rings it is preferably a cation of Formula 2

wherein R ¹ to R ⁵ are as defined in Formula 1;

R ⁶ is C^-alkyl;

R ⁷ and R ⁸ are as defined in R ⁴ and R ⁵ ; n is 1 to 6; and

X is a divalent linking group containing from 2 to 20 atoms. Preferably, R ⁶ is the same as R ² .

It is also preferred that R ⁷ and R ⁸ are the same as R ⁴ and R ⁵ , respectively.

The group X may be alkylene optionally substituted by hydroxy, alkyleneoxyalkyleneoxyalkylene, alkylenecarbonylaminoalkyleneaminocarbonylalkylene, alkylenecarbonylaminoalkyleneoxyalkyleneaminocarbonylalkylen e, alkylenearyienealkylene where arylene is phenylene or naphthylene or alkyleneoxyaryleneoxyalkylene.

Preferably, X is alkylene.

When X is alkylene, the number of carbon atoms is preferably at least 4 and especially at least 6. It is also preferred that the number of carbon atoms is less than 18, more preferably less than 16 and especially less than 14.

Preferably, R\ R ⁵ , R ⁷ and R ⁸ are hydrogen or C^-alkyi and especially hydrogen.

In one preferred embodiment, n is 1 in which case the cation of Formula 2 has two imidazolium rings. The preparation of suitable compounds for providing some cations of Formula 2 is described in GB 1 ,355,631.

Useful effects have been obtained with the following cations having two rings :- dodecyl-bis-(1 -decyl-2-methylimidazolium) cation; undecyl-bis-(1-decyl-2-methylimidazolium) cation; decyl-bis-(1-undecyl-2-methylimidazolium) cation;

RECTIFIED SHEET (RULE 91) ISA EP

nonyl-bis-(1-decyl-2-methylimidazolium) cation; nonyl-bis-(1-undecyl-2-methylimidazolium) cation; dodecyl-bis-(1-nonyl-2-methylimidazolium) cation; dodecyl-bis-( 1 -undecyl-2-methylimidazolium) cation; undecyl-bis-(1-undecyl-2-methylimidazolium) cation; dodecyl-bis-(1-decyl-2,4,5-trimethylimidazolium) cation; and the 2-ethyl (R ² and R ⁶ are ethyl) and imidazolium (R ² and R ⁶ are H) analogues thereof.

In a further preferred embodiment, n is 2 or 3 wherein the cation of Formula 2 contains three or four imidazolium rings, respectively. The preparation of compounds providing some of the cations of this type are described in WO 94/08972.

A still further preferred cation containing two or more imidazolium rings is that of Formula 3

wherein

R ² , R ⁴ and R ⁵ are defined as hereinbefore;

R ⁹ is hydrogen or methyl;

Y is hydroxy or halogen; and p is an integer. When Y is halogen, it is preferably chlorine or bromine. However, Y is preferably hydroxy. p is preferably at least 5, more preferably at least 10 and especially at least 20. It is preferred that p is less than 100, more preferably less than 70 and especially less than 50. The preparation of suitable compounds for providing some of the cations of

Formula 3 is described in GB 2,271,718.

When the cation contains two or more heterocyclic rings, those rings which do not form a salt linkage with an anionic group bome by the polymer form a salt linkage with a non-polymeric usually inorganic, counter ion. Suitable counter ions are halogen

such as chloride and bromide, methosulphate, bicarbonate, bisulphate, carbonate, sulphate and especially hydroxy. Halogen is less preferable since the presence of such counter ions can adversely affect metal surfaces to which the water-erodible polymer is applied. This is particularly true in the case of iron or steel surfaces, especially pipework, where the presence of halogen ions can promote corrosion.

The water-erodible polymer preferably has a saturated aliphatic backbone with chain-pendant (i.e lateral) anionic groups which may be tactically or atactically disposed along the polymer chain.

The heterocyclic salt of the polymer can be prepared by admixing the preformed polymer in which the anionic groups are in their free acid form or in the form of a salt of ammonia or alkali metal with a salt of the heterocycle, in which the counter ion is, for example, a halide, hydroxide, methosulphate, sulphate, carbonate or bicarbonate in a suitable liquid. The liquid is preferably organic and is preferably a solvent for the polymer and also the heterocyclic salt of the polymer since this facilitates the removal of inorganic salts formed during the reaction.

Preferably, however, the polymer is formed by (co)polymerisation of a reactive monomer containing an anionic group in the form of a heterocyclic salt as defined hereinbefore. Preferred reactive monomers contain an ethylenically unsaturated group. Examples of monomers which can be used in preparing the polymer containing anionic salt groups are acrylic acid, methacrylic acid, styrene sulphonic acid and preferably aliphatic sulphonic acid monomers such as 2-acrylamido-2-methyl- propane sulphonic acid (hereinafter AMPS), sulphoethyl methacrylate, vinyl sulphonic acid, methallyl sulphonic acid and propenesulphonic acid. Examples of phosphonic and phosphoric acid monomers are vinyl phosphonic acid, styrene phosphonic acid, 2- acrylamidopropane phosphonic acid, ethylidene-1 ,1 -diphosphonic acid and hydroxyethylacrylate monophosphate.

The water-erodible polymer may in principle be a homopolymer or copolymer of anionic salt containing monomer(s) but is preferably a copolymer obtainable by reacting the monomer(s) containing an anionic salt group, or anionic group in its free acid form when the intention is to form the salt groups subsequent to polymerisation, with one or more ethylenically unsaturated co-monomers which are preferably devoid of ionic salt groups and more especially of Formula 4.

CH ₂ = CR ¹⁰ COOR ¹¹ wherein

R ¹⁰ is hydrogen or C _M -alkyl; and

R ¹¹ is optionally substituted C^-alkyl, aryl or C.-. ₁₄ -cycloalkyl. When R ¹⁰ is C _M -alkyl it is preferably methyl.

When R ¹ is alkyl it may be linear or branched and is preferably C^-alkyl.

When R ¹¹ is aryl it is preferably phenyl.

When R ¹¹ is cycloalkyl it is preferably Ce. ₁₀ -cycloalkyl such as cyclohexyl.

When R ¹¹ is substituted C^-alkyl, the substituent is preferably hydroxy or an acyloxy (i.e alkyl carbonyloxy) group which preferably contains not greater than a total of six carbon atoms. The acyloxy group may itself be substituted with, for example, an alkyl carbonyl group as in an acetoacetoxyethyl group.

Preferred comonomers are aliphatic. Examples of such co-monomers are (meth)acrylic acid esters and amides such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, acetoacetoxy ethyl (meth) acrylate, 2-ethylhexyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, acrylonitrile, vinyl acetate, vinyl butyrate, and vinyl chloride. Aromatic ethylenically unsaturated monomers may also be used such as styrene, α-methyl styrene and vinyl pyridine.

The water-erodible polymer may be a copolymer obtainable from the monomer containing an anionic salt group and more than one ethylenically unsaturated co¬ monomer or from the monomer containing an anionic group in the form of its free acid and more than one ethylenically unsaturated comonomer where the anionic salt group of the heterocyclic cation is formed subsequent to polymerisation. Examples of such copolymers are those obtainable by polymerising a monomer containing an anionic group, or heterocyclic cation salt thereof, with methyl methacrylate and butyl acrylate or with ethyl methacrylate and 2-hydroxyethyl methacrylate.

The copolymer generally contains not less than 1, preferably not less than 3, more preferably not less than 5 and especially not less than 10 weight % monomer units containing an anionic salt group. It is also preferred that the amount of monomer units containing an anionic salt group is not greater than 80 weight % and especially not greater than 70 weight %.

The comonomers are preferably selected to give water-erodible polymers of desired glass transition temperatures (Tg) and also to control the rate of erosion of the

polymer and release of the heterocydic cation in use. Typically, the Tg is in the range from -20 to 100°C, preferably from -20 to 50°C and espedally from 5 to 50°C.

When it is desirable to increase the adhesion properties of the copolymer containing anionic salt groups which have as counter ions a biologically active heterocydic cation as defined hereinbefore, the copolymer may additionally contain free carboxylic add groups.

As a further aspect of the invention, the water-erodible polymer bears anionic salt groups some of which have counter ions in the form of quaternary ammonium cations which are derivable from a quaternary ammonium compound (hereinafter OAC), and/or amine cations.

When the water-erodible polymer does contain anionic salt groups with quaternary ammonium or amine cations, such groups are preferably not greater than 75%, more preferably not greater than 50%, even more preferably not greater than 30% and espedally not greater than 25% of the total number of anionic salt groups. The anionic salt groups with quaternary ammonium or amine cations, when present, are preferably not less than 5%, more preferably not less than 10% and espedally not less than 15% of the total number of anionic groups in the polymer. When such anionic salt groups are present they are preferably amine salts.

The OAC is preferably a tetra alkyl ammonium cation, or an alkyl ammonium cation which contains one or more cydoalkyl, aryl or aralkyl groups assodated with an anion which is preferably a halide, such as chloride or bromide, or a sulphate. The aralkyl group is preferably benzyl in which case the OAC is a benzalkonium compound. Where the OAC contains an aryl group it is preferably heteroaryl and especially pyridyl. The alkyl groups may be linear or branched, saturated or unsaturated, induding mixtures thereof.

In one preferred class of OAC, at least one of the alkyl groups contains at least 3, more preferably at least 6 and espedally at least 10 carbon atoms. Such QAC's contain an alkyl group preferably containing less than 30, more preferably less than 20 and espedally less than 18 carbon atoms. It is particularly preferred than such QAC's also contain a benzyl group.

Another preferred class of QAC's are those containing two alkyl groups containing from 3 to 30, more preferably from 6 to 20 and espedally from 10 to 18 carbon atoms.

Examples of QAC's are diethyldodecylbenzyl ammonium chloride; dimethyloctadecyl- (dimethylbenzyl) ammonium chloride; dimethyldidecylammonium chloride; dimethyldidodecylammonium chloride; trimethyl-tetradecylammonium chloride; benzyldimethyl(C ₁₂ -C ₁₈ -alkyl)ammonium chloride; dichlorobenzyldimethyldodecylammonium chloride; hexadecylpyridinium chloride; hexadecylpyridinium bromide; hexadecyltrimethylammonium bromide; dodecylpyridinium chloride; dodecylpyridinium bisulphate; benzyldodecyl-bis(beta-hydroxyethyl)ammonium chloride; dodecylbenzyltrimethylammonium chloride; dodecyldimethylethyl ammonium ethylsulphate; dodecyldimethyl-(1-naphthylmethyl)ammonium chloride; hexadecyldimethylbenzyl ammonium chloride; dodecyldimethylbenzyl ammonium chloride, trimethyl hydrogenerated tallow ammonium chloride, dimethyl di (hydrogenated tallow) ammonium chloride, trimethyl coconut ammonium chloride, dehydro abietyl trimethyl ammonium chloride and 1-(3-chloroallyl)-3,5,7-triaza-1-azonia-adamantane chloride. The amine is preferably a monoamine of Formula 5

_R 13

R ¹² -N-R ¹⁴ 5 wherein R ¹² is a C^ao-hydrocarbyl group; and

R ¹³ and R ¹⁴ is each, independently, hydrogen or C^o-hvdrocarbyl. When R ¹² to R ¹⁴ is hydrocarbyl it is saturated or unsaturated and can be aliphatic, aryl, aralkyl or heterocydic. Preferably the hydrocarbyl group or groups is aliphatic. When R ¹² to R ¹⁴ is aliphatic it may be linear or branched but is preferably linear.

Preferred amines are those wherein at least one of R ¹² to R ¹⁴ is alkyl. It is also preferred that at least one of the alkyl groups represented by R ¹² to R ¹⁴ contains at least 6, more preferably at least 8 and especially at least 12 carbon atoms. The alkyl group preferably contains less than 25, more preferably less than 20 and especially 18 or fewer carbon atoms.

Examples of other suitable amines are dodecylamine, hexadecylamine, octadecyl amine, oleylamine, tallow amine, hydrogenated tallow amine, coconutamine induding their benzyl, N-(C _M -alkyl) and N,N-di(C _lJr alkyl) derivatives.

It is particularly preferred that R ³ and R ¹⁴ are both C^-hydrocarbyl when the amine of Formula 5 is a tertiary amine such as methyl ditallowamine. It is preferred that R ¹² , R ¹³ and R ¹⁴ are the same and it is particulariy preferred that R ¹² , R ¹³ and R ¹⁴ are all alkyl and espedally where the total number of carbon atoms is between 12 and 54. Examples of such tertiary amines are tributylamine and trihexylamine.

Where the water-erodible polymer is used to coat solid surfaces in the food or health-care industries the polymer is preferably devoid of anionic groups having OAC and amine counter ions.

Polymerisation of the monomer containing an anionic group either in the form of a free add or as its salt with a biologically adive heterocydic cation can be caπied out by any method known to the art but is preferably caπied out in water or more preferably in a polar organic liquid using a free radical initiator. Preferred initiators are azo compounds such as azo-bis-iso-butyronitrile (hereinafter AIBN) and peroxides such as hydrogen peroxide and benzoyl peroxide. Other free radical initiators are cobalt chelate complexes and particularly Co(ll) and Co(III) complexes of porphyrins, dioximes and benzildioxime diboron compounds.

The organic liquid is preferably a polar liquid and may be a ketone, alcohol or an ether. Examples of suitable polar liquids are methyl ethyl ketone, acetone, methyl isobutylketone, methylisoamylketone, butyl acetate, methoxypropylacetate, ethoxyethylacetate, n-propanol, iso-propanol, n-butanol, iso-butanol, amyl alcohol, ethanol, diethylglycol mono-n-butyl ether and butoxyethanol. The polar organic liquid may also be used in admixture with a non-polar organic liquid. Preferred non-polar liquids are aliphatic hydrocarbons, chlorinated aliphatic hydrocarbons and espedally aromatic hydrocarbons. Examples of suitable non-polar organic liquids are heptane, hexane, methylene dichloride, chloroform, carbon tetrachloride, tri- and per- chloroethylene, trichloroethane, toluene and xylene.

When prepared by solution polymerisation (i.e. in an organic liquid) the number average molecular weight (Mn) of the water-erodible polymer is typically in the range 1,000 to 100,000. Preferably Mn is not less than 5,000 and more preferably not less than 10,000. Preferably Mn is not greater than 50,000 and espedally not greater than 25,000. The low molecular weight polymers having a Mn in the range 1,000 to 10,000 have been found espedally useful in high solids coatings.

The water-erodible polymer can also be made by aqueous emulsion or suspension polymerisation in which case Mn is much higher and is preferably in the range from 20,000 to 500,000.

The molecular weight can be controlled by the amount of initiator used or, more usually, by the use of appropriate chain transfer agents such as mercaptans, certain halohydrocarbons or cobalt complexes.

Where the anionic monomer containing an anionic group in the form of its free add exhibits very limited solubility in the organic liquid, as in the case of AMPS, polymerisation can be canied out in water but it is preferred to form the salt with the biologically-active heterocydic cation and to co-polymerise this salt in a polar organic liquid.

As noted hereinbefore, the polymers according to the invention are water- erodible. Thus, in use, the salt linkages between the anionic groups of the polymer and the biologically-active heterocydic cations in the outer layer of a polymeric cation coating obtainable by application of the defined coating composition to a substrate are believed to slowly dissodate in water, so releasing the heterocycle as an inorganic salt. In seawater, the heterocycle is probably released with one or more chloride counter-ions whereas in fresh water systems the heterocyde is more likely released as a hydroxide, carbonate or bicarbonate depending on the degree of hardness of the water. The outer layer of the polymer coating may also be released with the ionically attached heterocycle. As the polymer is gradually removed from the outer layer of the polymer coating a fresh layer of the anti-fouling polymer is continuously exposed thus preventing the attachment/build-up of organisms on the surface i.e. the polymeric coating exhibits self- polishing properties. A coating composition containing the water-erodible polymer may optionally contain a further biologically adive material or compound depending on its end use. Thus, according to a further asped of the invention there is provided a coating composition comprising a water-erodible polymer bearing anionic salt groups as defined hereinbefore and a further biologically material or compound. When the polymer is to be used as a coating on surfaces in contad with drculating water as in cooling towers or recreational water such as swimming pools the further biologically adive material or compound is preferably one which broadens the spedrum of adivity of the polymer relative to those micro-organisms which cause problems in such waters. Examples of such compounds are urea derivatives such as

1 ,3-bis(hydroxymethyl)-5,5-dimethylhydantoin; bis(hydroxymethyl)urea; tetrakis(hydroxymethyl)acetylene diurea; 3-(3,4-dichlorophenyl)-1,1 -dimethylurea; 3-(4- isopropylphenyl)-1,1 -dimethylurea; 1-(hydroxymethyl)-5,5-dimethylhydantoin and imidazolidinyl urea; amino compounds such as 1,3-bis(2-ethylhexyl)-5-methyl-5- aminohexahydropyrimidine; hexamethylene tetra amine;

1,3-bis(4-aminophenoxy)propane; and 2-[(hydroxymethyl)-amino]ethanol; imidazole derivatives such as 1[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1H-imidazol e; 2-(methoxycarbonylamino)-benzimidazole; nitrile compounds such as 2-bromo-2- bromomethylglutaronitrile, 2-chloro-2-chloromethylglutaronitrile, 2,4,5,6-tetra- chloroisophthalodinitrile; isothiazolin-3-ones such as 4,5-trimethylene-4-isothiazolin-3- one, 2-methyl-4,5-trimethylene-4-isothiazolin-3-one, 2-methylisothiazolin-3-one, 5-chloro- 2-methylisothiazolin-3-one, benzisothiazolin-3-one, 2-methylbenzisothiazolin-3-one, 2-n- butylbenzisothiazolin-3-one; 2-n-octylbenzisothiazolin-3-one; 2-n-hexylbenzisothiazolin-3- one; N-2-ethylbutylbenzisothiazolin-3-one; N-2-ethylhexylbenzisothiazolin-3-one; 2-octylisothiazolin-3-one, thiazole derivatives such as 2-(thiocyanomethylthio)- benzthiazole; and mercaptobenzthiazole; nitro compounds such as tris(hydroxymethyl)nitromethane; 5-bromo-5-nftro-1,3-dioxane and 2-bromo-2- nitropropane-1 ,3-diol; iodine compounds such as iodo propynyl butyl carbamate and tri- iodo allyl alcohol; aldehydes and derivatives such as glutaraldehyde (pentanedial), p-chlorophenyl-3-iodopropargyl formaldehyde and glyoxal; amides such as chloracetamide; N, N-bis(hydroxymethyl)chloracetamide; N-hydroxymethyl-chloracetamide and dithio-2,2-bis(benzmethyl amide); guanidine derivatives such as poly hexamethylene biguanide and 1,6-hexamethylene-bis[5-(4-chlorophenyl)biguanide]; thiones such as 3,5- dimethyltetrahydro-1,3,5-2H-thiodiazine-2-thione; triazine derivatives such as hexahydrσtriazine and 1,3,5-tri-(hydroxyethyl)-1,3,5-hexahydrotriazine; oxazolidine and derivatives thereof such as bis-oxazolidine; furan and derivatives thereof such as 2,5-dihydro-2,5-dialkoxy-2,5-dialkylfuran; carboxylic adds and the salts and esters thereof such as sorbic add and the salts thereof and 4-hydroxybenzoic add and the salts and esters thereof; phenol and derivatives thereof such as 5-chloro-2-(2,4-dichloro- phenoxy)phenol; thio-bis(4-chlorophenol) and 2-phenylphenol; sulphone derivatives such as diiodomethyl-paratolyl sulphone, 2,3,5,6-tetrachloro-4-(methylsulphonyl) pyridine and hexachlorodimethyl sulphone; and 2-mercaptopyridine-N-oxide and its metal complexes. The further biologically adive compound or material may also be a peroxide such as hydrogen peroxide, a perborate such as sodium perborate, halogen such as

chlorine or bromine, ozone or a chlorine release compound such as sodium or caldum isocyanurate.

When the polymer is to be used as a coating for surfaces in contad with sea¬ water the further biologically adive material or compound is preferably a marine biodde which is preferably sparingly soluble in water. A preferred marine biodde is a metalliferous pigment, particularly a copper, tin or zinc compound, which may be inorganic or organic. Examples of such compounds are cuprous oxide, cuprous thiocyanate, zinc oxide, zinc ethylene bis(dithiocarbamate), zinc dimethyl dithiocarbamate, zinc diethyl dithiocarbamate, cuprous ethylene bis(dithiocarbamate) and alkyl tin oxides such as tert butyltinoxide, induding mixtures thereof.

Other suitable non-metalliferous marine biocides are tetramethyl thiuram disulphide, methylene bis(thiocyanate) and captan.

The water-erodible polymer may also be used with, or the coating composition may also contain, a corrosion inhibitor espedally one which has no significant effed on the biological adivity of the heterocydic cation. Thus, accordingly to a still further asped of the invention there is provided a coating composition comprising a water-erodible polymer bearing anionic groups as defined hereinbefore and a corrosion inhibitor.

Preferred corrosion inhibitors are acrylates, borates, molybdates, polyethyleneimine, benztriazoles, nitrates, phosphates, complex inorganic phosphates and especially organic compounds containing one or more aminomethylene phosphate groups and organic aromatic compounds containing at least one 2-hydroxy-, 2-amino- or 2-mercapto-alkyl amino methylene group adjacent a phenolic hydroxyl group. Examples of specific corrosion inhibitors are aminomethylene phosphonic acid, 1 -hydroxy ethylidene di phosphonic add, sodium molybdate, sodium polyacrylate, sodium metaborate, sodium hexametaphosphate, 1,6-hexylenediamine-N,N,N',N'- tetra(methylenephosphonic acid), 2-(N-methyl-N-(2-hydroxy ethyl)amino methyl)phenol, and 2,3,5-tris-(N-methyl-N-(2-hydroxyethylaminomethyl)phenol.

As disdosed hereinbefore, one of the prindpal uses of the polymer according to the invention is for applying to a solid surface as a coating or paint or dear varnish. The polymer may be applied to the solid surface by any means known to the industry. When the polymer has been prepared by aqueous emulsion polymerisation it is preferable to apply the polymer as an aqueous formulation. When the polymer is prepared in a polar liquid, especially a water-misdble polar liquid, the polymer is preferably applied as a formulation containing a mixture of water and the polar liquid.

When the polymer is prepared in a non-polar organic liquid it is preferably applied to the solid surface as an aqueous emulsion of the non-polar organic liquid containing the polymer.

According to a still further asped of the invention there is provided a coating composition comprising a polymer bearing anionic salt groups as defined hereinbefore and an organic liquid.

Preferably, the organic liquid is a solvent for the polymer. The organic liquid is preferably the same as that used to prepare the monomer containing the anionic group which is in the form of a salt of a cation of the microbiologically active heterocydic cation. This may be diluted by a further organic liquid which is preferably an aromatic hydrocarbon. Examples of such aromatic hydrocarbons are xylene, toluene and trimethylbenzene.

The coating composition may also contain a pigment which may be any pigment commonly used in the paint or coating industry. Examples of suitable pigments are iron oxide, titanium dioxide and coloured pigments such as phthalocyanines espedally copper and nickel phthalocyanines.

The coating composition may also contain other adjuvants which are commonly used in the paint industry such as plastidsers, cross-linking agents, dispersants, defoamers, thickening and anti-settling agents, auxiliary film-forming resins and stabilisers against light and heat. The composition may also contain dyestuffs and particularly solvent-soluble dyestuffs.

When the coating composition contains an organic liquid, the organic liquid is preferably present in at least 20% and espedally at least 30% by weight of the composition. It is also preferred that the amount of organic liquid is less than 90%, and espedally less than 70% by weight of the composition.

The further microbiologically adive material or compound, if used, is present in an amount which is just suffident to inhibit the growth of micro-organisms. Preferably, the amount of the further microbiologically-active material or compound is not less than 1%, more preferably not less than 5% and espedally not less than 10% of the total weight of the composition. Preferably, the amount of the further microbiologically-adive material or compound is not greater than 60%, more preferably not greater than 50% and espedally not greater than 40% by weight of the composition.

The amount of corrosion inhibitor is preferably not less than 0.1%, more preferably not less than 1% and especially not less than 5% by weight of the

composition. It is also preferred that the amount of corrosion inhibitor is not greater than 25%, more preferably not greater than 20% and espedally not greater than 15% by weight of the composition.

The water-erodible polymer according to the invention can be used in any application where it is desirable to protect a surface from microbiological degradation and espedally where it is desirable to prevent organisms, and especially micro-organisms becoming attached to a surface. Thus, the water-erodible polymer according to the invention can be used in water treatment applications such as industrial cooling water, air conditioning units, central heating units, (de) humidifiers, heat exchangers, automobiles, swimming pools, spas and in pulp and paper mill liquors. The polymer may also be used as a coating for solid surfaces to provide solid surface disinfedion/sterilisation and can also be used in food processing outlets such as tunnel pasteurisers. It may also be used to coat medical items such as urinary catheters.

As noted hereinbefore, the polymer can be used as a marine antifouling coating. It can, however, also be used to coat timber and metal in general and also architedural strudures, especially those made of concrete and stone.

The monomer containing an anionic salt group in which the counter ion is in the form of a salt of a biologically adive heterocydic cation is novel.

As a further asped of the invention there is provided an ethylenically readive monomer containing an anionic salt group which is in the form of a salt of a biologically- adive heterocydic cation.

Preferably the anionic group is a carboxylic or sulphonic add anion. It is preferred that the number of carbon atoms in the ethylenically readive monomer is not greater than 20, more preferably not greater than 12 and especially not greater than 10. It is especially preferred that the monomer is AMPS or (meth)acrylic add.

Preferably the heterocydic cation contains one or more imidazolium rings. The invention is further illustrated by the following examples wherein all references are to parts by weight unless expressed to the contrary.

Example 1

Preparation of Dodecyl-bis-M-decyl^-methyl-imidazolium^dihydroxide

(a) Preparation of 1-Decyl-2-methylimidazole

Ref : Henri J.-M. Dou and Jacques Metzger, Bull. Soc. Chim. Fr. (1976) 1861

A mixture of 2-methylimidazole (12.3 parts; 0.15 mol), 1-bromodecane (33.15 parts; 0.15 mol), sodium hydroxide solution (69.5ml of 11.5M solution; 0.8 mol) and tetra- n-butylammonium bromide (1.85 parts; 0.006 mol) in toluene (300 ml) was stirred rapidly for 3 hours at 65°C. After cooling to between 20 and 25°C, the toluene layer was separated and extraded with 5M HCl solution (150 ml). The extrad was neutralised with sodium bicarbonate and extraded several times into hexane. The hexane solution was dried over magnesium sulphate and evaporated to dryness to give an oil (25 parts; 75% theory).

(b) Preparation of Dodecyl bis π-decyl-2-methylimidazoliutτn dibromide

1-Decyl-2-methylimidazole (22.2 parts; 0.1 mol) and 1,12-dibromododecane (16.4 parts; 0.05 mol) were heated together at 120-30°C for 2 hours. The mixture was cooled to room temperature and the resultant viscous oil was stirred with ethyl acetate to give a white solid which was recrystallised from ethyl acetate ethanol. Yield = 25.9 parts; 67% theory. M.pt. 114-7°C.

(c) Conversion of dibromide into dihydroxide

The bromide salt prepared as described in (b) above (41.7 parts; 0.054 mol) was dissolved in n-butanol (50 parts) at 20-25°C. Ground potassium hydroxide (6.05 parts; 0.108 mol) was added portionwise with stiπing for a further two hours when a copious white predpitate of potassium bromide separated. After stiπing for a further 2 hours the potassium bromide was removed by filtration through a G4 sinter and washed with butanol (15 parts) to give a solution of the dihydroxide salt (35 parts; 0.054 mol) as a 35% solution in butanol. This solution is Biodde 1.

Preparation of Monomers

Example 2

Preparation of AMPS/BIOCIDE monomer (1:1)

Biodde 1 (89.9 parts; 0.0485 mol) was stirred with 2-acrylamido-2- methylpropane sulphonic add (AMPS 10.1 parts; 0.0485 mol ex Lubrizol) to give a solution of a 1:1 monomer wherein the sulphonic add group of AMPS is in the form of an imidazolium salt and the unbound cationic centre is present as a hydroxide. This solution is Monomer 1 (Mw of 835).

Example 3

Preparation of AMPS/BIOCIDE monomer (2:1

Biodde 1 (74.1 parts; 0.04 mol) was stirred with 2-acrylamido-2methylpropane sulphonic add (AMPS 16.56 parts; 0.08 mol ex Lubrizol) to give a solution of a 2:1 monomer wherein the sulphonic add group of AMPS is in the form of an imidazolium salt.

This solution is Monomer 2 (MW of 1024).

Example 4

Preparation of the tri(2-ethylhexyπ amine salt of AMPS Tri-(2-ethylhexyl) amine (16.7 parts; 0.047 mol ex BASF) was dissolved in butanol (30 parts) and AMPS (9.8 parts; 0.047 mol) was added portionwise with stiπing at 20-25°C. The AMPS slowly dissolved on formation of the salt. This solution is Monomer 3 (MW561).

Example 5

Preparation of methylditallowamine salt of AMPS

Methylditallow amine (Armeen M2HT 26.2 parts; 0.05 mol ex AKZO) was dissolved in butanol (30 parts) and AMPS (10.35 parts; 0.05 mol) was added portionwise with stirring at 20-25°C. The AMPS slowly dissolved on formation of the salt. This solution is Monomer 4 (MW 731).

Example 6

Preparation of the N-benzyl-N N-dimethyl-N-(C _{ι:: ::1} -alkvn ammonium salt of AMPS

N-Benzyl-N,N-dimethyl-N-(C ₁₂ . ₂₄ -alkyl) ammonium chloride (28.3 parts; 0.08 mol. Vantoc CL ex Zeneca Ltd) was converted into its hydroxide using sodium hydroxide (3.2 parts; 0.08 mol) in butanol (40 parts). Sodium chloride predpitated and was filtered out, leaving a solution of the hydroxy analogue (26.7 parts; 0.08 mol) as a 40% solution in butanol.

This solution is Biodde 2.

The AMPS salt of this ammonium hydroxide was prepared by adding AMPS (16.56 parts; 0.08 mol) to Biodde 2 solution (66.7 parts of solution; 0.08 mol).

This solution is Monomer 5 (MW 523).

Example 7

Preparation of mixed amine and heterocyclic Monomer Salts Methylditallow amine (Aimeen M2HT 20.9 parts; 0.04 mol ex AKZO) was added to Biodde 1 (74.1 parts of solution 0.04 mol). AMPS (16.56 parts; 0.08 mol) were added with stiπing at 20-25°C whereupon the solution gradually deared as the amine salt of the AMPS formed.

This solution is Monomer 6 and the two components AMPS/amine and AMPS/biodde have a MW of 731 & 835 respedively.

Example 8

Preparation of the copolymer containing Monomer 1

Monomer 1 (100 parts of solution 0.0485 mol ex Example 2), ethyl methacrylate (EMA 17.96 parts; 0.1575 mol), 2-hydroxyethyl methacrylate (2-HEMA 4.73 parts; 0.0364 mol) and 1-dodecaπthiol (0.98 parts; 0.0049 mol) was stirred together under nitrogen. The temperature was then raised to about 80°C and azoisobutyronitrile (AIBN 0.27 parts; 0.00162 mol) in butanol (6 parts) was added with stiπing under nitrogen. After 30 mins a further aliquot of AIBN (0.53 parts; 0.00323 mol) in butanol (8.2 parts) was added and the readion continued at about 80°C. A further aliquot of AIBN (0.32 parts; 0.0019 mol) in butanol (6 parts) was added after 3 hours reaction. The reactants were stirred for a further 1 hour at 80°C under nitrogen, filtered hot through a G1 sinter and allowed to cool.

This copolymer in butanol is hereinafter referred to as Polymer 1 which contains a 1:1 ratio of bisimidazolium cation to sulphonic add residue of the copolymer and the other remaining imidazolium cationic centre is present as its hydroxide (Molar ratio of monomers 20:65:15).

Example 9

Preparation of a copolymer 2 containing Monomer 2

This was prepared in a similar manner to that described in example 8 except the following quantities of readants were used in place of those amounts described in Example 8.

1. Monomer 2 solution 90.7 parts; 0.04 mol

2. ethyl methacrylate 10.2 parts; 0.089 mol

3. 2-hydroxy ethyl methacrylate 2.36 parts; 0.0182 mol

4. butanol 17 parts

5. 1-dodecanthiol 0.633 parts; 0.0031 mol

6. azoisobutyronitrile 0.171 parts; 0.00104 mol

7. azoisobutyronitrile 0.343 parts; 0.00209 mol

The solution of copolymer in butanol is hereinafter referred to as Polymer 2 which contains a 2:1 ratio of bis imidazolium cation for each sulphonic add group, such that both cationic centres are present as the sulphonate salt. (Molar ratio of monomers 27.1:60.5:12.4).

Example 10

Preparation of copolymer containing the AMPS salt of 1 ,3-didecyl-2-methyl imidazolium cation

The AMPS salt was prepared in an analogous manner to that described in

Example 2 except that 1 ,3-didecyl-2-methyl imidazolium hydroxide was used in place of the dimeric imidazolium hydroxide. This AMPS salt was then copolymerised with EMA and HEMA to give a copolymer of AMPS EMA HEMA in a mole % ratio of 20:65:15 using an analogous process to that described in example 8. This copolymer is hereinafter referred to as Polymer 3.

Example 11

Preparation of copolymer containing Monomer 4

Example 1 was repeated except that Monomer 1 was replaced by Monomer 4 to give a copolymer of AMPS/EMA/HEMA in the mole % ratio of 20:65:15. This polymer is hereinafter referred to as Polymer 4.

Example 12

Preparation of copolymer containing Monomer 5

Example 1 was again repeated except that Monomer 1 was replaced by Monomer 5 to give a copolymer of AMPS EMA/HEMA in the mole % ratio of 20:65:15. The polymer is hereinafter referred to as Polymer 5.

Example 13

Preparation of copolymer containing Monomer 6 Monomer 6 (71.5 parts of solution 0.0436 mol ex Example 7), butyl methacrylate (BMA 40 parts; 0.2817 mol), iso-butyl methacrylate (i-BMA 25 parts; 0.1761 mol) and butanol (44 parts) was stirred under nitrogen. Monomer 6 (0.0436M) contains a mixture of AMPS/biocide (0.03M) and AMPS/M2HT (0.0136M). The temperature was then raised to about 80°C and azobisisobutyronitrile (AIBN 0.167 parts; 0.00102 mol) in butanol (6 parts) was added with stirring under nitrogen. After 30 mins a further aliquot of AIBN (0.333 parts; 0.00203 mol) in butanol (8.2 parts) was added and the readion continued at about 80°C. A further aliquot of AIBN (0.2 parts, 0.00122 mol) in butanol (6 parts) was added after 3/4 hours readion. The readants were stirred for 1 hour at 80°C under nitrogen, filtered hot through a G1 sinter and allowed to cool. This copolymer in butanol (hereinafter referred to as Polymer 6) contains a 1:1 ratio of bisimidazolium cation to sulphonic add anions in the copolymer and the other remaining imidazolium cationic ring is present as its hydroxide.

The Molar ratio of monomers is 6.0:2.7:56.2:35.1 (AMPSBiodde:AMPS/M2KT:BMA:IBMA).

Examples 14. 15 and Comparative Examples A and B

The polymer dissolved in butanol (0.2ml), was coated into a glass slide, dried for 4 hours at 20 to 25°C and then stored at 40°C ovemight to dry the film.

Each coated slide was then immersed for 5 days in 40 ml distilled water. The slides were then removed and the immersion repeated for a second and third time.

Each of the distilled water samples was then inoculated with Ecoli to give an initial cell amount of E4 to E5 cfu/ml. Viable counts were determined after 15 mins and 3 hours for each water sample. The results are given in Table 1 below which clearly show that the imidazolium polymer salts exhibit higher aπti-baderial adivity than the amine and benzalkonium salts and that the ionically bound biodde is released faster into the aqueous environment in the case of the two imidazolium polymer salts.

Table 1

Ex Polymer Counter Viable Cells/ml after immersion in distilled water ion

1st immersion 2nd immersion 3rd immersion

15 min 3hrs 15 min 3hrs 15 3hrs min

14 3 DD1 <10 <10 <10 <10 <10 <10

15 1 DB1 <10 <10 <10 <10 <10 <10

A 4 M2HT 2.6 E4 <10 6.4E4 4.4 2.8 4.6 E4 E4 E2

B 5 BZ <10 <10 <10 <10 1.5 4.2 E4 E3

Control 4.6 1.2 7.6 E4 E5 E4

Footnote to Table 1 DD1 1,3-didecyl-2methyiimidazolium cation DB1 Dodecyl-bis-(1-decyl-2-methyiimidazolium) cation monohydroxide M2HT N-Methyl-N,N-ditallowamine BZ N-benzyl-N,N-dimethyl-N-(C ₁₂ . ₂₄ -alkyl) ammonium cation E is an exponential value

Examples 16. 17 and Comparative Example C

Three of the coated slides from Examples 14, 15 and B were immersed repeated in distilled water for up to 10 immersions and the anti-microbial adivity after challenge with E coli determined after a 15 minute corrtad time. The results are given in Table 2.

Table 2

Ex Polymer Counter Viable cells/ml in distilled water after indicated ion immersions

4 6 8 10

16 3 DD1 <10 <10 <10 <10

17 1 DB1 <10 <10 <10 <10

C 5 BZ 6.6 E2 5.1 E3 >3.0 E5 1.7 E4

Control - - 5.5 E3 4.8 E3 2.7 E4 6.6 E3

Footnote to Table 2

DD1, DB1, BZ and E are as in footnote to Table 1.

Examples 18.19 and Comparative Example D Inhibition of biofilm formation

Polymers 1,3 and 5 where each coated onto one surface of a PVC coupon (6 x 4 ins) from a 0.2ml solution in butanol. The coupons were then dried at 25°C for 4 hours and then individually supported vertically in 2.5 litres tap water which had been incubated with 2ml Pseudomonas fluorescens NC1B 9046 broth culture.

After an incubation each coupon was then transferred into 2 litres fresh tap water containing 2 ml glucose solution.

The coupons were then incubated for a further period of 16 and 23 days at 20- 25°C and were then placed in 2 litres distilled water containing 20 ml nutrient broth and 5ml glucose.

After a total incubation period of 29 days, the coupons and surrounding water were examined as follows :-

(a) scrapings from the polymer coated surface were transferred into 4.5 ml sterile distilled water containing 0.002% (w/w) Noridet P40. The samples were mixed in a Vortex mixer for 20 seconds and the number of viable cells determined by serial dilution and transfer onto both minimal agar supplemented with glucose and nutrient agar.

(b) scrapings were taken from the uncoated surface and evaluated as described in a) above.

(c) the number of viable cells in the surrounding was determined by streaking a loopful of the water onto nutrient agar.

The results are given in Table 3 below which clearly show that the polymer containing the imidazolium cation inhibited the formation of a biofilm on the treated surfaces of the coupon and also released the cation at a rate sufficient to prevent growth in the surrounding water and also the development of a biofilm on the uncoated surface of the coupon. In these respeds, the imidazolium polymer was significantly better than equivalent polymers containing an amine and benzyalkonium cation, respedively.

Table 3

Ex Polymer Counter Viable Cells ion

Coated uncoated Water surface surface (cells/ml) (cells/ml)

18 1 DB1 2.5 E1 5.0 E1 -

19 4 M2HT >1.0 E6 >1.0 E6 I I 1 1

D 5 BZ 0.7 E6 >1.0 E6 +++

Footnote to Table 3

DB1 ,M2KT, BZ and E are as in the footnote to Table 1. - no growth +++ heavy growth ++++ very heavy growth

Example 20

Emulsion Polymerisation

Example 1c was repeated except that the n-butanol was replaced by the same amount of methylated spirits (95/5, ethanol/methanol). The dodecyl bis (1-decyl-2-methyl imidazolium)dihydroxide so obtained was readed with AMPS as described in Example 2 to give a AMPS/Biodde monomer (1:1). The solvent was finally evaporated. This is Monomer 7 and was used to prepare the following copolymer. Reagents

Monomer feed iso-butylmethacrylate 24.10 parts

Ethomeen T12 (Surfadant) 1.32 parts Monomer 7 3.81 parts Seed iso-butylmethacrylate 1.46 parts

Reador water 62.77 parts

Ethomeen T12 0.01 parts

20% hydrochloric add 0.015 parts iron (II) sulphate 0.007 parts

Initiator 27% hydrogen peroxide 0.12 parts water 5.88 parts

Burn-up 27% hydrogen peroxide 0.03 parts water 0.50 parts

Method The reador reagents were stirred under nitrogen and the temperature was raised to 60°C. The seed was then added, followed by an aliquot of the initiator mixture (0.67 parts). The pH was measured at 3.0. After 30 minutes the monomer mixture was added drop-wise over approximately 2 hours; every 15 minutes a further aliquot of initiator mixture (0.67 parts) was added to the reador. The pH was monitored and if necessary adjusted to pH 3.0. On completion of the feed and inrtiator the polymerisation was left at 60°C for a further 30 minutes, before the burn-up mixture was added. The polymerisation was then left for a further 60 minutes at 60°C.

The resulting emulsion was free of residual monomers and had a solids content of 30% (wt wt); average particle size of 250nm and a minimum film forming temperature of 42°C. This is Polymer 7.

Examples 21-28

The following copolymers were prepared using a similar method to that described in Example 13. The amount of each monomer (% wt) is given in Table 4:

Table 4

Polymer AMPS MAA Biodde Armeen BMA Molar Ratio Add/

Example (% wt) (% wt) (%wt) M2HT (%wt) (biodde+Armeen) (% wt)

21 10 0 25 5 60 1:1

22 10 0 20 8.8 61.2 1:1

23 12.7 0 20 15.8 51.5 1:1

24 12.7 0 25 11.5 50.8 1:1

25 15 0 20 5 60 2:1

26 15 0 20 21.7 43.3 1:1

27 0 5 25 10.3 59.7 1:1

28 0 3.2 25 0 71.8 1:1

Footnote to Table 4

AMPS is 2-acryamido-2-methylpropane sulphonic add

MAA is methacrylic add

Biodde is dodecyl bis(1-decyl-2-methylimidazolium) cation

Armeen M2HT is methylditallowamine

BMA is n-butylmethacrylate

In the above copolymers all the anionic groups of either AMPS or MMA are in the form of a salt with Biodde or Armeen. The molar ratio of 2:1 indicates that the Biodde forms a salt linkage at each end of the molecule with an anionic monomer unit (prior to polymerisation). In the case of a molar ratio of 1:1 the cationic group not forming a salt with an ionic monomer unit is present as the hydroxide.

These copolymers were subjed to three test protocols, namely resistance to mould growth (mould growth test), inhibition of biofilm formation (drculatory water test) and resistance to mould growth in humid conditions (condensation test). Details of the three test protocols are as follows:-

(a) Mould Growth Test

Polymers were coated onto polyester strips (6 by 2 inches) to give a dry coat thickness of one micron. The strips were inoculated by spraying with 2ml of a suspension of spores (10 ⁶ /ml) of Aspergillus niger, Aureobasidium pullulans, Altrenaria altemata, Cladiosporium herbarum and Phoma violacea prepared in distilled water supplemented with 10% (wv) malt broth and 10% (w/v) Czapek Dox broth. The strips were then incubated for 3 days at 20°C in a humidity chamber and then inspeded for fungal growth. After rinsing one half of the strip with 20ml sterile water the strips were reinoculated by spraying with 2ml of spore suspension and incubated a further 3 days. This 3 day cyde was repeated until the coating failed (i.e. fungal growth was visible at the edges or surface of the coated strips).

(b) Circulatory Water Test

80 micron thick coatings of polymer were applied to rigid PVC sheets (4cm by 11cm). The coatings were then subjeded to a constant stream of circulating water containing a mixed culture of microorganisms (10 ⁵ -10 ^s /ml of Pseudomonas fluorescens and additional unidentified tap water organisms). About 85% of the water was replaced weekly with tap water and a fresh inoculation of microorganisms added. The extent of biofilm formation was measured by swabbing the surfaces of the coatings each week and quantifying the organisms dislodged by serial dilution and plating. (c) Condensation Test

Coatings (approx 25 micron) of polymer were applied to aluminium test-piece surfaces. An inoculum of airborne microorganisms (unidentified airborne baderia and fungi) was prepared in an inorganic nutrient medium solution containing glucose as carbon source. The coated aluminium was dipped into the inoculum and allowed to drain. The aluminium substrates were cooled to approximately 7°C and the aluminium test pieces placed within a humidity chamber. Condensation dripping from the test- pieces was colleded in a container under each sample. The temperature of the samples was cyded daily between 25°C and 7°C. The condensate under each sample was removed after 7 days and plated out to test for microorganisms. The coated aluminium samples were then dipped in fresh inoculum, allowed to drain, replaced in the humidity chamber for a further 7 days. This cyde of sampling, re-inoculation and incubation was repeated.

The results from the three test protocols are given in Table 5. These date show that the copolymers wherein the Biodde forms a salt with only one anionic

monomer unit (1:1 ratio) is superior to those wherein the Biodde forms a salt with two anionic monomer units. Furthermore, copolymers derived from MMA are at least as good as those derived from AMPS in inhibiting mould growth.

Table 5

Polymer Example Mould Growth Test Circulatory Water Condensation Test Test

Number of days Baderial surface Microbial content protedion (surface growth (colony- of condensate free from visible forming units/cm ² ) after 15 weeks mould growth) (colony-forming units/cm ³

Baderia/Fungi)

21 69 19 -

22 69 18 -

23 21 100 -

24 60 54 0/0

25 10 - -

26 17 - -

27 >79 - -

28 47 - -

Control* 3 1000 10^3400

Footnote to Table 5

* The control for the mould growth test was uncoated polyester film, filled PVC for the drculatory water test and an acrylic coating not containing any biocide for the condensation test.

Example 29

Dodecyl bis (1-decyl-2-methyl imidazolium)dichloride (0.68 parts, 0.001 M ex Example 1) was dissolved in ethanol (2 parts). Sodium hydroxide (1 part of a solution containing 4 parts NaOH in 103.5 parts ethanol 0.001 M NaOH), was added with stiπing whereupon the sodium chloride separated and was removed by filtration. The resultant solution of the imidazolium dihydroxide was added to a solution of a copolymer of AMPS

with BMA (15% w/w AMPS; 1.38 parts in 12.77 parts ethanol). The polymer so obtained contains a 1:1 molar ratio of biodde to sulphonic add residue i.e. the bis imidazolium cation forms one salt linkage with the copolymer and the other imidazolium unit is in the form of a hydroxide salt.

Example 30

Example 29 was repeated except that 50% of the imidazolium salt was used. The resultant co-polymer contains a 1:2 molar ratio of biodde to sulphonic acid groups in the polymer i.e. both imidazolium units form a salt link with the copolymer.

Example 31

Dodecyl bis(1-decyl-2-methylimidazolium)dichloride (0.56 parts) was dissolved in ethanol (2 parts). A solution of sodium hydroxide (1 ml of a solution containing 4 parts NaOH in 103.5 parts ethanol; 0.0008M NaOH) was added and the sodium chloride removed by filtration. The biodde solution was added to a copolymer of MMA and BMA (10% w/w MMA; 0.07 parts dissolved in 2.14 parts ethanol). The resulting copolymer contained a 1:1 molar ratio of biodde to carboxylic add groups in the copolymer.

Example 32 Example 31 was repeated using 50% of the biodde to give a polymer having a

1:2 molar ratio of biodde to carboxylic add groups in the copolymer.

Example 33 to 36

The biodde polymers of Examples 29-32 were subjeded to the mould growth test protocol described in Examples 21-28. The results are given in Table 6 below:

Table 6

Example Copolymer AMPS MMA BMA Polymer Time to of content of content of (%wt) biodde failure

Example copolymer copolymer molar (days) (% wt) (%wt) ratio

33 29 15 0 85 1:1 >41

34 30 15 0 85 2:1 >41

35 31 0 10 90 1:1 >41

36 32 0 10 90 2:1 27

Control - - - - 3

Footnote to Table 6

Biodde, AMPS, MMA and BMA are as described in the footnote of Table 4.

Examples 37 to 41

Biodde copolymers were prepared by repeating Example 29 but repladng the biocide with the equivalent molar amount of the following heterocydic biodde molecules.