WO1998052875A1

WO1998052875A1 - Inhibition of water mould in recreational circulating water

Info

Publication number: WO1998052875A1
Application number: PCT/GB1998/001363
Authority: WO
Inventors: Paula Louise Mcgeechan; Roy Vore
Original assignee: Zeneca Limited; Zeneca Inc.
Priority date: 1997-05-22
Filing date: 1998-05-13
Publication date: 1998-11-26
Also published as: GB9710448D0; ZA984175B; AR015813A1; AU7439198A

Abstract

A method for inhibiting the growth of water mould and fungi in a recreational circulating water system such as a swimming pool which comprises adding a mono C14-18-alkyl quaternary ammonium chloride to the water system.

Description

INHIBITION OF WATER MOULD IN RECREATIONAL CIRCULATING WATER

The present invention relates to the use of a quaternary ammonium compound to inhibit the growth of water mould in recreational circulating water systems such as swimming pools and especially those systems utilising polymeric biguanides as the primary sanitiser. The water in recreational circulating water systems such as swimming pools is constantly recirculated and fresh water is normally added only to maintain the desired volume. Although the water is usually filtered continuously to keep it free from suspended matter, it is constantly exposed to infection by bacteria, fungi and algae and chemical treatment to control this infection is necessary for reasons of hygiene. The main disinfectant used in swimming pools at present is chlorine, or chlorine- release compounds such as chloroisocyanurates, which is effective at inhibiting the growth of micro-organisms such as bacteria, fungi and algae but suffers from the disadvantages that it causes eye and skin irritation and also has to be added at frequent intervals to maintain an effective concentration. As an alternative to chlorine, GB 1 ,407,258 discloses the use of linear polymeric biguanides for inhibiting the growth of micro-organisms such as bacteria and algae in swimming pools. Whilst these linear polymeric biguanides have proved both popular and effective, it has been found that under certain circumstances some swimming pools and spas have developed a water mould such as Paecilomyces lilacnus which is more resistant to the linear polymeric biguanides. Whilst the development of such water mould does not in itself constitute a health hazard it is aesthetically unwelcome.

Quaternary ammonium compounds (hereinafter QAC's) have also been added to swimming pools which are maintained on chlorine or chlorine-release compounds and also to swimming pools maintained on linear polymeric biguanides in order to provide additional protection against the growth of algae. Examples of such QAC's are N-oleyl, N,N,N-trimethylammonium chlorine; N,N-didecyl-N,N-dimethylammonium chloride; N- decyl-N-isononyl-N,N-dimethylammonium chloride; N,N-di-(C₈.₁₀-alkyl)-N,N- dimethylammonium chloride and N-(C₁₂.₁₆-alkyl)-N-benzyl-N,N-dimethylammonium chloride. However, none of these QAC's are particularly effective at controlling the growth of water mould in swimming pools maintained either on chlorine or linear polymeric biguanides as primary sanitiser.

It has now been found that QAC's containing a C₁₄.₁₈-alkyl chain are particularly effective at inhibiting the growth of water moulds, especially those which are resistant to linear polymeric biguanides such as Paecilomyces lilacnus. According to the present invention there is provided a method for inhibiting the growth of water mould and fungi in a recreational circulating water system which comprises adding to the water system a QAC of formula 1 ; R ¹ R — N — R ³ X ^"

(1) wherein

R is C₁₄.₁₈-alkyl;

R³ is C_M-alkyl or a group -Y-N⁺R⁴R⁵R⁶ X^"; R\ R², R⁴, R⁵ and R⁶ is each independently C₁_₄-alkyl;

Y is C^-alkylene; and

X is an anion which forms a neutral molecule. R to R⁶ may be linear or branched but are preferably linear. Preferably, R is C₁₆.₁₈-alkyl; Preferably, R¹ and R² are the same, and it is especially preferred that both R¹ and

R² are methyl.

When R³ is C^-alkyl, it is preferably methyl.

Y is preferably propylene.

It is also preferred that R⁴, R⁵ and R⁶ are the same and especially that R⁴, R⁵ and R⁶ are methyl.

The anion X may be organic but is preferably inorganic. When X is inorganic it is preferably halogen and especially chloride or bromide. Examples of other suitable anions are bisulphate, bicarbonate, methosulphate, sulphate, carbonate, acetate, propionate and butyrate. In the case of divalent counter ions such as sulphate and carbonate it is to be understood that the divalent counter ion forms a neutral molecule with either two QAC molecules of Formula 1 (R³ is C^-alkyl) or with one QAC molecule of Formula 1 (R³ is the group -Y-⁺NR⁴R⁵R⁶ X^").

Many QAC's of Formula 1 are available commercially as mixtures, particularly those derived from animal fat amines and especially those derived from tallow amines. The alkylamines in animal fat amines vary depending on the source of the animal fat and although predominantly saturated in nature they often contain some unsaturated aliphatic amines such as oleylamine.. Where it is expedient to derive the QAC of Formula 1 from animal fat amines, any unsaturated amines present should preferably be not greater than 20%, more preferably not greater than 15%, even more preferably not greater than 10% and especially not greater than 5% based on the total weight of amine. QAC's of Formula 1 which are obtainable from saturated amines or hydrogenated mixtures of animal fat amines have been found especially useful. N-(C₁₄.₁₈-alkyl)-N,N,N-trimethylammonium chloride and N-(C₁₄.₁₈-alkyl)- N,N,N',N',N'-pentamethyl-1 ,3-propylene diammonium dichloride have been found especially useful in inhibiting the growth of water mould.

The compound of Formula 1 may be used to inhibit the growth of water mould in any recreational circulating water system such as a swimming pool, Jacuzzi, spa and the like. Whereas it may be used where chlorine or a chlorine-release compound is the primary sanitiser it has been found especially beneficial where the primary sanitiser is a linear polymeric biguanide or mixture thereof. The sanitiser and compound of Formula 1 may be added to the recreational water sequentially but it is especially beneficial to add the two together.

According to a further aspect of the invention there is provided a composition comprising a linear polymeric biguanide and a compound of Formula 1.

The linear polymeric biguanide, or salt thereof, has in its free base form a recurring polymer unit represent by the formula:

— X-NH-C-NH-C-NH-Y-NH-C-NH-C-NH—

II II II II

NH NH NH NH wherein X and Y represent bridging groups in which together the total number of carbon atoms directly interposed between the pairs of nitrogen atoms linked by X and Y is more than 9 and less than 17.

The bridging groups X and Y may consist of polymethylene chains, optionally interrupted by hetero atoms, for example, oxygen, sulphur or nitrogen. X and Y may also incorporate cyclic nuclei which may be saturated or unsaturated, in which case the number of carbon atoms directly interposed between the pairs of nitrogen atoms linked by X and Y is taken as including that segment of the cyclic group, or groups, which is the shortest. Thus, the number of carbon atoms directly interposed between the nitrogen atoms in the group

— NH-CH₂-O O-CH₂-NH — is 4 and not 8.

The preferred polymeric biguanide is poly(hexamethylene biguanide), in which X and Y both represent the group -(CH₂)₆- (hereinafter PHMB). Polymeric biguanides may be prepared by the reaction of a bisdicyandiamide having the formula:

CN-NH-C-NH-X-NH-C-NH-CN

II II

NH NH with a diamine H₂N-Y-NH₂, wherein X and Y have the meanings defined above; or by reaction between a diamine salt or dicyanimide having the formula:

with a diamine H₂N-Y-NH₂ wherein X and Y have the meanings defined above. These methods of preparation are described in UK specifications numbers 702,268 and

1 ,152,243 respectively, and any of the polymeric biguanides described therein may be used with the QAC of formula 1.

The polymer chains are terminated either by an amino group or by a

— NH-C-NH-CN II NH group, and the terminating groups may be the same or different on each polymer chain.

A small proportion of a primary amine R-NH₂, where R represents an alkyl group containing from 1 to 18 carbon atoms, may be included with the diamine H₂N-Y-NH₂ in the preparation of polymeric biguanides as described above. The primary monoamine acts as a chain-terminating agent and consequently one or both ends of the polymeric biguanide polymer chains may be terminated by an -NHR group. The use of these chain- stopped polymeric biguanides may also be used with the QAC of formula 1.

It is to be understood that by either of the above-described methods the polymeric biguanides are obtained as mixtures of polymers in which the polymer chains are of different lengths, the number of individual biguanide units, i.e. X-NH-C -NH-C -NH— and

II II

NH NH

Y-NH-C-NH-C-NH —

II II

NH NH together being from 3 to about 80.

In the case of the preferred poly(hexamethylene biguanide) having the formula:

the value of n is in the range from 6 to 10, the average molecular weight of the polymer mixture being from about 1100 to about 1800.

The linear polymeric biguanide readily forms water-soluble salts with inorganic and organic acids. Examples of suitable acids are acetic and hydrochloric acids.

The ratio of polymeric biguanide to compound of Formula 1 is preferably between 10:1 to 1 :10, more preferably between 5:1 and 1 :5 and especially between 2:1 and 1 :2. For ease of transportation, the composition comprising the polymeric biguanide and compound of Formula 1 is preferably an aqueous solution containing not less than

10%, more preferably not less than 15% and especially not less than 20% by weight of the polymeric biguanide and compound of Formula 1. The amount of the polymeric biguanide and compound of Formula 1 is preferably not greater than 40%, more preferably not greater than 30% and especially not greater than 25% by weight of the composition.

The amount of compound of Formula 1 which is required to inhibit the growth of water mould in a recreational water is preferably not greater than 30 ppm, more preferably not greater than 20 ppm and especially not greater than 15 ppm. Preferably, the amount of compound of Formula 1 added to the recreational water is not less than 1 ppm, more preferably not less than 3 ppm and especially not less than 5 ppm.

The amount of polymeric biguanide in the recreational water is preferably not greater than 50 ppm, more preferably not greater than 30 ppm and especially not greater than 20 ppm. Preferably, the amount of polymeric biguanide in the recreational water is not less than 1 ppm, more preferably not less than 5 ppm and especially not less than 7 ppm.

The pH of the aqueous concentration comprising linear polymeric biguanide and compound of Formula 1 is preferably not greater than 5 and especially not greater than 4 as determined using an indicator and as described in EP 485079. The concentrate may also contain other additives which are commonly used with aqueous concentrates of linear polymeric biguanides which are available commercially as swimming pool sanitisers such as fragrances and colourants.

The compound of Formula 1 can be used with other chemicals which are commonly used in recreational waters. Examples of such chemicals include metal sequestrants such as ethylenediamine tetra acetic acid (hereinafter EDTA), water clarifiers such as peroxy compounds including hydrogen peroxide, alkali metal perborates and persulphates and water-balancing and/or alkalinity-balancing chemicals such as calcium chloride and sodium bisulphate. As a further aspect of the invention there is provided a recreational water, especially a swimming pool, spa or Jacuzzi containing a compound of Formula 1.

Preferably, the recreational water also contains a linear polymeric biguanide.

The invention is now further illustrated by the following non-limiting examples wherein all references are to parts and percentages by weight unless indicated to the contrary.

Examples 1 and 2 and Comparative Examples A to E

A 35 litre glass tank equipped with an external filter containing 15 parts silica sand was charged with water containing 100 ppm sodium bicarbonate (total alkalinity) and 200 ppm calcium chloride (total calcium hardness). The pH was adjusted to 7.5 by adding sodium bisulphate. EDTA and poly(hexamethylene biguanide) hydrochloride (PHMB ex. Zeneca) was then added to give a final concentration in the tank of 10 ppm for each additive. The QAC under evaluation was also added to give a final tank concentration of 10 ppm.

In order to simulate a bather load, 100 ml synthetic perspiration was added at an initial concentration of 5-fold strength and after 5 days a 20 ml aliquot at normal strength was added daily during the remainder of the tank trial.

The composition of the synthetic perspiration (normal strength) was ammonium sulphate (161.3 ppm), urea (277.1 ppm), uric acid (3.6 ppm), creatinine (23.2 ppm), creatine (1.0 ppm) and casamino acid (57.1 ppm). This synthetic perspiration was made up weekly and stored at 4°C.

The inoculum was a PHMB-resistant strain of Paecilomyces lilacnus isolated from a PHMB-maintained swimming pool and Pseudomonas aeruginosa ATCC 27853. The Paecilomyces lilacnus was grown on Czapeks Dox agar containing 30 ppm

PHMB at 25°C for 1 week. It was then scraped into saline to form a fungal spore suspension of initially 10⁶ colony forming units (cfu) per ml. This was later increased to 10⁸ cfu per ml. Each tank was initially inoculated twice weekly with 1 ml containing 10⁶ cfu increasing to thrice weekly with 1 ml containing 10⁸cfu. The Pseudomonas aeruginosa was grown overnight at 37°C on Tryptone soya agar and harvested using physiological saline to give a bacterial suspension of 10⁶ cfu per ml. Each tank was inoculated twice weekly with 1m of this bacterial suspension.

The tanks were maintained at 20 to 25°C throughout and the total alkalinity maintained at 100 ppm. The water hardness was also maintained at 200 ppm and the PHMB concentration was maintained at 10 ppm. The amount of QAC was also maintained at 10 ppm.

During the course of the tank trials the water was examined twice weekly for microbial contamination by determining the presence of sessile fungal growth on the sides of the tank, filter surface and on the surface of a pan-scrub placed in each tank. Fungal growth was assessed visually using a scale of 0 to 10 where 0 represents no growth and 10 represents heavy growth. The results are given in Table 1 below after 12 weeks and show that QAC's containing a C₁₄.₁₈-alkyl saturated alkyl chain and a trimethyl ammonium residue are superior to shorter chain analogues, benzalkonium analogues and QAC's containing an unsaturated long alkyl chain. Table 1

Footnote to Table 1

(a) Arquad T50 ex. Akzo Nobel

(b) Duoquad T50 ex. Akzo Nobel

(c) Arquad S50 ex. Akzo Nobel

(d) Arquad 210-50 ex. Akzo Nobel

(e) Bardac 208M ex. Lonza

(f) Barquat MB-50 ex. Lonza

(g) Bardac 2180 ex. Lonza

Example 3 Examples 1 and 2 were repeated except that the amount of EDTA was reduced to

5 ppm and the QAC was maintained either between 5 and 10 ppm or between 10 and 15 ppm as indicated.

Since water mould grows more effectively in non-turbulent regions of the tank, such as corners, the circulating pumps in the tanks were switched off with a glass slide set at 45° in each corner of the tank behind which was placed a pan-scrub. The growth of water mould in these non-turbulent regions was assessed visually and the time taken for growth to occur is recorded in Table 2 below. Table 2

Footnote to Table 2 a, b, f and g are as explained in the footnote to Table 1.

Claims

1. A method for inhibiting the growth of water mould and fungi in a recreational circulating water system which comprises adding to the water system a QAC of formula 1

(1) wherein

R is C₁₄.₁₈-alkyl;

R³ is C^-alkyl or a group -Y-N⁺R⁴R⁵R⁶ X^";

R\ R², R⁴, R⁵ and R⁶ is each independently C^-alkyl; Y is C^-alkylene; and

X is an anion which forms a neutral molecule.

2. A method as claimed in Claim 1 wherein R is C₁₆_₁₈-alkyl.

3. A method as claimed in either Claim 1 or Claim 2 wherein R¹, R² and R³ is methyl.

4. A method as claimed in either Claim 1 or Claim 2 wherein Y is propylene.

5. A method as claimed in Claim 4 wherein R¹, R², R⁴, R⁵ and R⁶ is methyl.

A composition comprising a QAC of Formula 1 :

(1) wherein

R is C₁₄.₁₈-alkyl; R³ is C_M-alkyl or a group -Y-N⁺R⁴R⁵R⁶ X^";

R\ R², R⁴, R⁵ and R⁶ is each independently C_M-alkyl;

X is an anion which forms a neutral molecule; and a linear polymeric biguanide, or salt thereof.

7. A composition as claimed in Claim 6 wherein the linear polymeric biguanide has, in its free base form, a recurring polymer unit represented by the formula:

— X-NH-C-NH-C-NH-Y-NH-C-NH-C-NH—

II II II II

8. A composition as claimed in Claim 7 wherein X and Y both represent -(CH₂)₆-.

9. A composition as claimed in any one of Claims 6 to 8 wherein the biguanide is poly(hexamethylenebiguanide) having the formula:

-(CH₂)₆-NH-C-NH-C-NH- II II

NH NH wherein n is from 6 to 10.

10. A composition as claimed in any one of claims 6 to 9 wherein the ratio of polymeric biguanide to QAC is between 1 :10 and 10:1.

1 1. A recreational circulating water system containing a QAC of Formula 1 :

R R — N - -R ^: X ^"

R ^:

(1) wherein

R is C₁₄.₁₈-alkyl;

R³ is C..₄-alkyl or a group -Y-N⁺R⁴R⁵R⁶ X^";

R¹, R², R⁴, R⁵ and R⁶ is each independently C_,.₄-alkyl;

Y is C,.₆-alkylene; and

X is an anion which forms a neutral molecule.

12. A system as claimed in Claim 1 1 which is a swimming pool or spa.