Monoquaternary ammonium or phosphonium salt biocides and monoquaternary heterocyclic amine salt biocides are known as having rapid activity particularly when applied on hard surfaces, but they suffer from the disadvantage of having to be used in relatively high amounts.

It has been proposed, in order to control biocide release, to provide a liquid biocidal composition containing the biocide and a film forming polymer or copolymer such as polyvinylpyrrolidone, copolymers of vinylpyrrolidone and vinyl acetate, copolymers of vinyl ethers and maleic anhydride (GB-A-1 553 132), acrylic or methacrylic copolymers (EP-A-0 290 676) or terephthalic copolyesters (WO 97/06675). The polymer or copolymer film formed on the hard surface holds and protects the biocide, which is slowly released to give extended disinfectancy, by resistance to washing.

Such compositions suffer the disadvantage that they contain a relatively high concentration of polymer compared to the concentration of biocide; besides the increase in cost, this prevents the provision of rapid disinfection.

Further it may also create problems in formulation because

most of these polymers are insoluble in water, and thus difficult to formulate in aqueous products.

Thus, a need exists for a biocidal product and a biocidal composition capable of being both rapid acting and long lasting and which can be used at low level.

According to the present invention, there is provided a biocidal system which is able to provide both in-built rapid acting disinfection (for example as little as 5 minutes after having been applied to a hard surface) and in-built extended disinfectancy (for example 24 hours, indeed 3 days or more after having been applied to said hard surface). This biocidal system is composed of a combination of a monocationic salt biocidal agent and a polymeric cationic salt compound; isobolograms show that the agent and compound mutually support each other very significantly in their effects and that a lower concentration of biocide is required to achieve the same effect; impact on the environment is thus reduced.

Further, said biocidal system is easy to formulate, particularly in non-ionic active cleaners.

According to the present invention, there is provided a rapidly active and long lasting biocide system (BS) in the form of an aqueous solution comprising water, as solvent, and at least 1% by weight of at least one watersoluble first biocidal agent which is a monoquaternary ammonium or phosphonium salt or a monoquaternary heterocyclic amine salt (M); and

at least 3% by weight of at least one watersoluble second biocidal agent which is a polymeric quaternary ammonium salt, polymeric quaternary heterocyclic amine salt or polymeric cationic biguanide salt (P).

Preferably at least one non-ionic, amphoteric or zwitterionic surfactant is present.

The present invention also provides the use in a biocidal aqueous composition (BAC), of a biocide system (BS) as defined above as well as a method for the biocidal treatment of a hard surface which comprises applying to said surface a biocidal aqueous composition (BAC) as defined above.

The (BAC) is preferably a hard surface treatment or cleaning composition.

Suitable biocidal agents include: -mono-or-di- (higher alkyl) quaternary ammonium salts such as N-higher alkyl-N-aryl-N, N-di (lower alkyl) ammonium salts such as R'R'R'R'N+X- where R1 is optionally chloro substituted benzyl, or C1-C4 alkyl benzyl, C8-C24alkyl,R2is R3 and R4 are each independently C1-C4 alkyl or C1-C4 hydroxyalkyl, and

X- is a water solubilising anion such halide (e. g. chloride, bromide, iodide), sulfate, or methylsulfate.

Generally"lower alkyl"as used herein, means alkyl of 1 to 4 carbon atoms while"higher alkyl"means alkyl of at least 8 carbon atoms.

Specific examples include coco-alkyl benzyl dimethylammonium chloride, Cl2-Cl4 alkyl benzyl dimethyl ammonium chloride, coco-alkyl dichlorobenzyl dimethylammonium chloride and tetradecyl benzyl dimethylammonium chloride.

*N, N-di (higher alkyl)-N, N-di (lower alkyl) ammonium salt such as RlR2R3R4N+x- where R1 and R2 are each independently, C8-C24 alkyl, R3' and R4' are each independently, C1-C4 alkyl, and X- is a water solubilising anion such as defined above, such as dodecyl dimethylammonium chloride and dioctyl dimethylammonium chloride.

*N-higher alkyl-N, N, N-tri (lower alkyl) ammonium salts such as where R"is Cg-Cz4 alkyi R2, R3" and R4" are each independently C,-C, alkyl, and

X-is a water solubilising anion such as defined above such as myristyl trimethylammonium bromide and cetyl trimethylammonium bromide.

-monoquaternary heterocyclic amine salts such as laurylpyridinium chloride, cetylpyridinium chloride, C12- C14-alkyl-benzyl imidazolinium chloride.

-higher alkyl triphenyl phosphonium salts wherein the anion is generally a water solubilising anion as defined for X, such as-myristyl triphenyl phosphonium bromide.

(P) is water soluble and is a biocide such as: -polymers from the reaction of *epichlorhydrin and dimethylamine or diethylamine e. g. poly [hydroxyethylene (dimethylamino)-2- hydroxypropyl (dimethylamino) methylene dichloride]; *epichlorhydrin and imidazole; *1,3-dichloro-2-propanol and dimethylamine; *1,3-dichloro-2-propanol and 1,3-bis-dimethylamino-2- propanol; *ethylene dichloride and 1,3-bis-dimethylamino-2-propanol; *bis (2-chloroethyl) ether and N, N, N', N'-tetramethylethylene diamine e. g. polyoxyethylene (dimethylamino) ethylene (dimethylamino) dichloride; *bis (2-chloroethyl) ether and N, N'-bis (dimethylaminopropyl) urea or thiourea; *polymeric biguanidine hydrochloride such as VANTOCIL IB

(ICI).

These (P) polymers generally have a molecular weight from 500 to 1,000,000 preferably from 1,000 to 40,000.

The weight ratio (dry basis) (M)/ (P) in (BS) is generally from 10/90 to 90/10, preferably 15/85 to 80/20, particularly 20/80-40/60 and especially about 25/75.

(BS) is preferably in the form of an aqueous concentrate containing up to, say, 50,65 or 70%, preferably up to 30 or, 35 or 40%, by weight of (M) + (P) (dry basis). It can be prepared by simply mixing solutions of (M) and (Q).

Thus, typically, the concentrate will contain 1 to 20 or 30%, especially 1 or 5 to 10 or 15t by weight of (M) and 3 to 60%, especially 15 to 30%, by weight of (P).

(BS) can be used as a rapid and long lasting biocide agent (additive) in a biocidal aqueous composition (BAC), typically in an amount from 3 to 300 ppm, preferably 5 to 100 ppm, by weight (dry basis).

(BS) and/or (BAC) can contain at least one non-ionic, amphoteric or zwitterionic surfactant. Typically the concentration of surfactant in (BAC) is 0.01% to 1% by weight while the weight ratio of surfactant/ (BS) is 0.2/1 to 8/1 preferably 1/1 to 5/1.

Examples of suitable non-ionic surfactants include block polymers of ethylene oxide and propylene oxide, polyethoxylated sorbitan esters, sorbitan fatty esters, ethoxylated fatty esters (e. g. 1-25 oxyethylene units), ethoxylated C8-C22 alcohols (e. g. 1-12 oxyethylene units), polyethoxylated C6-C12 alkylphenols (e. g. 5-25 oxyethylene units), alkylpolyglycosides, amine oxides (such as Go-ci alkyldimethylamineoxides, C8-C22 alkoxyethyl dihydroxyethylamineoxides).

Examples of suitable amphoteric or zwitterionic surfactants include C6-C20 alkylamphoacetates or alkylamphodiacetates (such as cocoamphoacetates), Clo-Cl8 alkyldimethylbetaines, Clo-C1g alkylamidopropyldimethylbetaines, Clo-Cl8 alkyldimethyl sulphobetaines, Clo-C18 alkylamidopropyldimethyl sulphobetaines.

In a preferred embodiment, (BAC) is an aqueous hard surface treatment or cleaning composition.

Other possible ingredients of the composition include: * chelating agents such as aminocarboxylates (ethylenediaminetetraacetates, nitrilotriacetates, N, N- bis (carboxymethyl) glutamates), citrates; * builders such as phosphates, silicates; * alcohols such as ethanol, isopropanol, glycols; * Perfumes and colorants.

The (BAC) compositions can be prepared simply by dilution of (BS) in water.

When other additives are present in (BAC) compositions, said additives can be added either to the (BS) system or to the dilution water or to the diluted formulation, said additives are preferably introduced in (BS) when (BS) is a solution.

Examples of microorganisms which can be controlled include: (i) Gram negative bacteria: Pseudomonas aerucrinosa; Escherichia coli; and Proteus mirabilis.

(ii) Gram positive bacteria: Staphylococcus aureus; and Streptococcus faecium.

(iii) Other harmful food bacteria: Salmonella typhimurium; Listeria monocvtogenes; Campylobacter jejuni; and Yersinia enterocolitica.

(iv) Yeasts: Saccharomyces cerevisiae; and Candida albicans.

(v) Fungi: Aspergillus niger; Fusarium solani; and Pencillium chrysogenum.

(vi) Algae: Chlorella saccharophilia; Chlorella emersonii; Chlorella vulgaris; and Chlamydomonas eugametos.

The microorganisms controlled by the method of the present invention are preferably Gram negative microorganisms, especially Pseudomonas aeruginosa, Gram positive microorganisms, especially Staphylococcus aureus, and fungi e. g. Aspergillus niger.

The (BAC) compositions may be applied to the hard surface by coating, spraying, dipping, brushing or wiping, for example. It can be used as surface disinfectant for floors, walls, working surfaces, equipment, furniture, instruments, in hospitals, food plants, breweries and the home (e. g. kitchens and bathrooms). Examples of hard surfaces which can be treated include glazed or unglazed ceramics, glass, PVC, plastic laminate and other hard plastics, stainless steel or other painted or unpainted metals and painted or unpainted wood as well as flexible polymer surfaces.

The amount used will, of course, depend to some extent on the nature of the surface but, generally, total actives should amount to 1 to 1000 ppm, preferably 5 to 500 ppm and more preferably 5 to 100 ppm.

The following Examples further illustrate the present invention.

Test protocol for evaluation of (M)/ (P) biocide system (BS) for biocidal activity according to AFNOR 72.150 Standard Test Conditions *biocide dilutions : prepared in distilled water *test organism : Pseudomonas aeruginosa ATCC

*temperature : 20°C *contact time : 5 minutes and extended to 24 hours *organic matter : Nil *inactivator solution : 3% Tween 80 + 2% Soya Lecithin *result : dilution to give 5 log reduction, i. e. 99.999% kill Procedure 1. Prepare serial dilutions of (M)/ (P) biocidal system (BS) with different ratios (M)/ (P); 2. inoculate said test dilutions with Pseudomonas aeruginosa bacterial suspension; 3. sample after 5 minutes and 24 hours, by transferring lml of test dilution to 9 mls of inactivator solution; 4. plate out inactivated test dilution on nutrient agar, incubate at 37°C for 48 hours and assess for bacterial survivors; 5. calculate dilution which gives 5 log reduction in bacterial numbers.

When all the results had been collated, the E Fractional Bacterial Concentration (E FBC) was calculated for each particular blend.

The Fractional Bacterial Concentrations (FBC) method compares the biocidal effect of each biocide compound when used in the biocide mixture to the effect produced when

each biocide compound is used alone.

FBC = concentration in the mixture/concentration when used alone E FBC = FBC (M) + FBC (P) E FBC = 1 corresponds to a normal additive effect E FBC = >1.0 corresponds to antagonism E FBC = <1.0 corresponds to synergy Example 1 The tested biocide system (BS) consists of a blend of -RHODAQUAT RP 50 (Rhone-Poulenc), an aqueous solution containing 50% solids of Cl2-Cl4 alkyl benzyl dimethyl ammonium chloride; -and GLOKILL PQ (Rhone-Poulenc), an aqueous solution containing 50% solids of a polymer from epichlorhydrin and dimethylamine.

The five following dilutions were prepared RHODAQUAT RP50 10% 7. 5% 5. 0% 2. 5% 0% ppmactive 50, 000 37, 500 25, 000 12,500 0%2.5%5.0%7.5%10%GLOKILLPQ 12,50025,00037,50050,000ppmactive waterto 100%to 100%to 100%to 100% to 100% 5 minutes test results RP50 PQ Biocidal actives in ppm FBC FBC ZFBC dilution RP 50 PQ RP50 PQ 10% 0% 1: 1000 50 0 5% 5% 1 : 750 33.33 33.33 0.66 0.33 1 1:50001000%10% 24 hours test results

RP50 PQ Biocidal actives in ppm FBC FBC EFBC dilution RP 50 PQ RP50 PQ 10% 0% 1 : 2000 25 0 7. 5% 2.5% 1 : 3500 10.71 3.57 0.428 0.286 0.714 5% 5% 1 : 4000 6. 25 6.25 0.250 0.500 0.750 2. 5% 7.5% 1 : 5500 2.27 6.82 0.091 0.546 0.637 0%10%1: 40000 12. 5 An additive effect can be noted after 5 minutes (but no antagonism) and a significant synergy after 24 hours, particularly for the ratio RP50/PQ of 1/3.

Example 2 Example 1 is repeated replacing GLOKILL PQ by GLOKILL ELC (Rhone-Poulenc), an aqueous solution containing 50k solids of a polymer from epichlorphydrin and imidazole.

24 hours test results BiocidalactivesinppmRP50ELC FBC FBC #FBC dilution RP 50 ELC RP50 ELC 10°w 0W 1 7. 5% 2.5% 1 : 4000 9.37 3. 125 0.375 0.375 0.750 5%5%1: 5000 5. 00 5.00 0.200 0.600 0.800 2. 5% 7.5% 1 : 6000 2. 08 6.25 0.083 0.750 0.833 0%10%1: 6000 0 8.33 Synergy after 24 hours can be noted here too