Biocidal compositions

Abstract: Mixtures of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one with certain commercial biocides in specified amounts demonstrate synergy and afford especially effective, and broad control of microorganisms in various systems.

Description: This invention is concerned with biocidal compositions including an isothiazolone biocide and one or more specified commercial biocides which demonstrate synergism in providing more effective and broader control of micro-organisms in various industrial systems. More particularly, the invention combines a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one with one or more of the following 14 compounds: Hexahydro-1,3,5-triethyl-2-triazine; 5-bromo-5-nitro-1,3-dioxane; 2-(hydroxymethyl)amino-ethanol; 2-(hydroxymethyl)amino-2-methylpropanol; α-benzoyl-α-chloroformaldoxime; benzylbromoacetate; p -chloro- m -xylenol; bis-(2-hydroxy-5-chlorophenyl)sulfide; p -tolydiiodomethylsulfone; 3-iodo-2-propynylbutylcarbamate; bis-(2-hydroxy-5-chlorophenyl) methylene; dipropylamine ether; dodecylamine; and 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride. As used herein the term "biocide" is intended to include, but is not restricted to, bactericides, fungicides and algicides; and biocidal activity refers to both the elimination of and also the inhibition of growth of bacteria, fungi and algae. The isothiazolones for use in this invention are described in U.S.-A-3,761,488; 4,105,431; 4,252,694; 4,265,899 and 4,279,762. An excellent antimicrobial agent is a mixture of 75% 5-chloro-2-methyl-4-isothiazolin-3-one and 25% 2-methyl-4-isothiazolin-3-one, which is very effective against bacteria, fungi, and algae. The suggested dosages, sometimes, cannot achieve the best results for the control of microorganisms due to interfering nucleophiles, or due to less sensitive organisms in certain systems. To control the situations like these will need higher concentration of active ingredient which increases the treatment cost. Therefore, the search for more effective and broader control method to achieve the best results has continued. Many other broad classes of biocidal agents are known. They are commercially available for the control of microorganisms in certain sections of various industrial systems such as paints, wood, textile, paper, pulp, leather, fur, tobacco, rope, plastics, fuel, oil, cosmetics, rubber, adhesives, latex emulsions, joint cements, water treatment, laundry, and metalworking industries, and the like. In general, high dosage requirements make them disadvantageous because of high treatment cost and interference with the formulation of finished product or the operation of the system. Sometimes many biocides cannot provide satisfactory performances even at high use concentrations due to weak activity against certain bacteria or fungi. Without effective control, loss of product, inferior product, production-time loss, health hazard, and other types of problems may occur in the systems. We have now found that combinations of a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one with one or more of the 14 compounds mentioned above within a specified range of ratios results in synergistic biocidal activities against a wide range of microorganisms. The synergy by which the disruptive interaction on the organisms by the two compounds together is greater than the sum of both compounds taken alone, is unexpected in view of the known activity of the components. The synergistic combinations unexpectedly provide more effective and broader control of microorganisms in a number of industrial systems. Important applications of the synergistic biocidal compositions of the present invention include but are not limited to: inhibiting the growth of bacteria and fungi in aqueous and organic paints, adhesives, latex emulsions, and joint cements; preserving wood; preserving cutting fluids, controlling slime-producing bacteria and fungi in pulp and papermills and cooling towers; as a spray or dip treatment for textiles and leather to prevent mold growth; protecting paint films, especially exterior paints from attack by fungi which occurs during weathering of the paint film; protecting processing equipments from slime deposits during manufacture of cane and beet sugar; preventing microorganism buildup and deposits in air washer or scrubber systems and in industrial fresh water supply systems; controlling micro-organisms contamination and deposits in oil field drilling fluids and muds, and in secondary petroleum recovery processes; preventing bacterial and fungal growth in paper coating processes; controlling bacterial and fungal growth and deposits during the manufacture of various specialty boards, e.g., carboard and particle board; preventing sap stain discoloration on freshly cut wood of various kinds; controlling bacterial fungal growth in clay and pigment slurries of various types; as a hard surface disinfectant to prevent growth of bacteria and fungi on walls, floors, etc.; in swimming pools to prevent algae growth; inhibiting the growth of harmful bacteria, yeasts, fungi on plants, trees, fruits, seeds, or soil; protecting animal dip compositions against the buildup of microorganisms, and in photoprocessing to prevent buildup of microorganisms, and the like. The components of the synergistic compositions of this invention may be added separately to the system or locus on or in which microorganisms are to be controlled or may be formulated as a simple mixture comprising its essential ingredients, or together with a suitable carrier or solvent, or as an aqueous emulsion or dispersion. The invention therefore provides a microbicidal (biocidal and/or anti-microbial) composition comprising, as a first component 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in a weight ratio of 1:1 to 100:1, preferably 2:1 to 4:1, most preferably about 3:1 (Component A) and, as a second component, one or more of the following compounds (Component B) wherein the range of weight ratios of Component A to Component B (A:B) is from 8:1 to 1:200. The Component B compounds are: hexahydro-1,3,5-triethyl-2-triazine; 5-bromo-5-nitro-1,3-dioxane; 2-(hydroxymethyl)amino-ethanol; 2-(hydroxymethyl)amino-2-methylpropanol; α-benzoyl-α-chloroformaldoxime; benzylbromoacetate; p -chloro- m -xylenol; bis-(2-hydroxy-5-chlorophenyl)sulfide; p -tolydiiodomethylsulfone; 3-iodo-2-propynylbutylcarbamate; bis-(2-hydroxy-5-chlorophenyl)methylene; dipropylamine ether; dodecylamine; and 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride. The invention also provides a method of inhibiting the growth of bacteria, fungi or algae in a locus subject or susceptible to contamination by bacteria, fungi or algae, which comprises incorporating into or onto the locus in an amount which is effective to adversely affect the growth of bacteria, fungi or algae one or more of the synergistic combinations described above. The compositions of the invention can be formulated as solutions in water. While the amount of the instant composition in the formulated solution can vary over a wide range, the solutions can conveniently be formulated to contain from about 5 to about 100 ppm of the composition in solution, with the preferred range of the composition being from about 10 to 50 ppm. In formulating the solutions, other solvents which are water-miscible, such as ethyl alcohol, propyl alcohol, isopropyl alcohol, diethylene glycol, dipropylene glycol, polyethylene glycol, diethylene glycol ethyl ether, and the like, may be employed in order to aid in solubilizing the active components. Furthermore, various other conventional additives may be employed, such as surfactants, dispersing agents, corrosion inhibitors, and the like. In general, the weight ratio of the first Component A to Component B is from about 8:1 to 1:200. The other preferred ratios are given in the Examples which follow. The synergistic combinations have a wide range of applications, including all areas where each individual biocide and preservative is currently employed. In addition, the synergistic combinations can be used beyond their original intended uses because of the newly-acquired, more effective broader spectrum of activities. The synergism of these two-component combinations is demonstrated by testing a wide range of concentrations and ratios of compounds, generated by two-fold serial dilutions in a liquid growth medium of a biocide in one dimension and another biocide in the second dimension, against a bacterium Escherichia coli (ATCC 11229) or a fungus Candida albicans (ATCC 11651), or a mixed culture of bacteria and fungi which are natural contaminants of a metalworking fluid, or a more tolerant pseudomonad isolated from a surfactant. Each test tube was inoculated to about 2 x 10⁷ bacteria per ml or 2 x 10⁶ fungi per ml. The lowest concentrations of each compound or mixtures to inhibit visible growth (turbidity) at 37°C for E. coli and at 30°C for the Pseudomonad, C. albicans , or the mixed culture for over 2 days is the minimum inhibitory concentration (MIC). The lowest concentration of each component of the mixtures to kill 99.9% of fungi or 99.999% of bacteria after a certain period of exposure from 1 day to 7 days is taken as minimum biocidal concentration (MBC). Both MIC and MBC are taken as end points of activity. End points for the mixtures of Component A and Component B were then compared with the end points for Component A alone and Component B alone. Synergism was determined by an industrially accepted method described by Kull, F.C.; Eisman, P.C.; Sylwestrowicz, H.D. and Mayer, R.L., in applied Microbiology 9:538-541 (1961) using the ratio determined by Qa QA + Qb QB = Synergy Index (SI) wherein QA = concentration of Component A in parts per million (ppm), acting alone, which produced an end point. Qa = concentration of Component A in ppm, in the mixture, which produced an end point. QB = concentration of Component B in ppm, acting alone, which produced an end point. Qb = concentration of Component B in ppm, in the mixture, which produced an end point when the sum of Qa/QA and Qb/QB is greater than one, antagonism is indicated. When the sum is equal to one additivity is indicated, and when less than one synergism is demonstrated. The test results for demonstration of synergism of biocide combinations are shown in Table 1 through Table 14. Each table is organized to show: 1. the specific combination of Component A and Component B; 2. test against E. coli (Ecol) or C. albicans (Calb), or a pseudomonad species (P. sp), or a mixed culture of bacteria and fungi (mixed); 3. test medium by either trypticase soy broth (TSB) or a minimal salt medium + 0.2% glucose (M9G); 4. the method of evaluation (test) by either MIC or MBC. The MBCld means MBC determined after 1-day exposure to biocides. MBC2d means MBC determined after 2-days exposure to biocides, etc.; 5. the end-point activity in ppm measured by MIC or MBC for Component A alone (QA), for Component B alone (QB), for Component A in the mixture (Qa), or for compound B in the mixture (Qb); 6. the calculation for synergy index (SI) based on the formula SI=Qa/QA + Qb/QB , and for the ratio of Component A to Component B in the synergistic combinations (Qa:Qb); 7. the range of weight ratios for synergism and the preferred ratios. As can readily be seen by inspection of Table 1 through Table 14, the compositions of the invention demonstrate synergistic antimicrobial activities as measured by minimum inhibitory concentrations (MIC) and synergistic biocidal activity as measured by minimum biocidal concentrations (MBC), and show surprisingly greater activity than the algebraic sum of the individual ingredients which make up the respective composition. The synergistic activities in most cases are applicable to bacteria, fungi, and a mixture of bacteria and fungi. Thus, the combinations not only lower the use-level of biocide but also broaden the spectrum of activity. This is especially useful in situations where Component A does not achieve the best results due to weak activity against certain organisms. A number of examples, as shown in Tables 1, 2, 3, 5, 9, 10 and 11 demonstrate the advantages of using synergistic combination for the control of a less sensitive pseudomonad. Two examples of non-synergistic combinations of Component A with 2,4-dichlorobenzylalcohol and Component A with 3,5-dimethyltetrahydro-1,3,5-(2H)-thiadiazine-2-thione are demonstrated in Table 15 and Table 16, respectively. Table 15 is an example of no effect by the combination of two compounds. The activity of Component A (MIC=0.31 ppm) was not affected by the absence or presence up to 500 ppm of 2,4-dichlorobenzylalcohol. The activity of 2,4-dichlorobenzylalcohol (MIC=500 ppm) was not affected by Component A from 0 to 5 ppm. Thus, no increase or decrease of activity can be attributed by the combination. Table 16 is an example of antagonistic effect by the combination of Component A and 3,5-dimethyltetrahydro-1,3,5-(2H)-thiadiazine-2-thione because there was a loss of activity of Component A due to the presence of 3,5-dimethyltetrahydro-1,3,5-(2H)-thiadiazine-2-thione in the combination.

Claims: A biocidal composition comprising a first Component (A) 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in a weight ratio of 100:1 to 1:1 and a further Component (B) which is one or more of the following compounds: hexahydro-1,3,5-triethyl-2-triazine; 5-bromo-5-nitro-1,3-dioxane; 2-(hydroxymethyl)amino-ethanol; 2-(hydroxymethyl)amino-2-methylpropanol; α-benzoyl-α-chloroformaldoxime; benzyl bromoacetate; p -chloro- m -xylenol; bis-(2-hydroxy-5-chlorophenyl)sulfide; p -tolydiiodomethylsulfone; 3-iodo-2-propynylbutyl carbamate; bis-(2-hydroxy-5-chlorophenyl)methylene; dipropylamine ether; dodecylamine; and 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride; wherein the weight ratio of Component (A) to Component (B) is from about 8:1 to about 1:200.. A composition of claim 1, wherein the ratio of Component (A) to hexahydro-1,3,5-triethyl-s-triazine as Component B is from 4:1 to 1:100. A composition of claim 1, wherein the ratio of Component (A) to 5-bromo-5-nitro-1,3-dioxane as Component (B) is from 1:16 to 1:100. A composition of claim 1, wherein the ratio of Component (A) to 2-(hydroxymethyl)amino-ethanol as Component (B) is from 1:25 to 1:200. A composition of claim 1, wherein the ratio of Component (A) to 2-(hydroxymethyl)amino-2-methylpropanol as Component (B) is from 1:100 to 1:200. A composition of claim 1, wherein the ratio of Component (A) to α-benzoyl-α-chloroformaldoxime as Component (B) is from about 1:4 to about 1:31. A composition of claim 1, wherein the ratio of Component (A) to dipropylamine ether and/or benzylbromoacetate as Component (B) is from about 1:6.2 to about 1:50. A composition of claim 1, wherein the ratio of Component (A) to p -chloro- m -xylenol as Component B is from about 1:1.6 to about 1:200. A composition of claim 1, wherein the ratio of Component A to bis-(2-hydroxy-5-chlorophenyl)sulfide as Component B is from about 1:50 to about 1:200. A composition of claim 1, wherein the ratio of Component (A) to p -tolyldiiodomethylsulfone as Component (B) is from about 8:1 to about 1:20. A composition of claim 1, wherein the ratio of Component (A) to 3-iodo-2-propynylbutyl carbamate as Component (B) is from about 1:1 to about 1:25. A composition of claim 1, wherein the ratio of Component (A) to bis-(2-hydroxy-5-chlorophenyl)methylene as Component (B) is from about 2:1 to about 1:50. A composition of claim 1, wherein the ratio of Component (A) to dodecylamine as Component (B) is from about 1:2.5 to about 1:20. A composition of claim 1, wherein the ratio of Component (A) to 1-(3-chloroallyl)-3,5,7-triaza-azoniaadamantane chloride as Component (B) is from about 1:6.2 to about 1:200. A composition of claim 1 wherein the ratio of isothiazolones in Component (A) is 2:1 to 4:1. A composition of Claim 1 wherein the ratio of isothiazolones in Component (A) is about 3:1. A biocidal product containing from about 10 to about 50 ppm of Components (A) plus (B). A method for inhibiting the growth of bacteria, fungi, or algae in a locus subject or susceptible to contamination fungi, or algae, which comprises incorporating onto or into the locus, in an amount which is effective to adversely affect the growth of bacteria, fungi, or algae, a composition of any preceding claim. A method of claim 18 wherein the locus is an aqueous medium. A method of claim 18 or 19 wherein the composition is present in an amount of 5 to 100 ppm of Components (A) plus (B).

Inventors: HSU JEMIN CHARLES, HSU, JEMIN CHARLES
Applicants: ROHM & HAAS, ROHM AND HAAS COMPANY
Application year: 1989
Main classification: A01N43
IPC codes: A01N43, A01N47, A01N41, A01N33, A01N31