Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N57/00—Biocides, pest repellants or attractants, or plant growth regulators containing organic phosphorus compounds
  • A01N57/34—Biocides, pest repellants or attractants, or plant growth regulators containing organic phosphorus compounds having phosphorus-to-halogen bonds; Phosphonium salts

Definitions

• the present invention relates to synergistic antimicrobial compositions which are generally useful for inhibiting microbial growth wherever such microbial growth is found, for example in aqueous systems related to a wide variety of industrial applications. More particularly, the present invention relates to synergistic admixtures of peroxyacetic acid and a phosphorus compound. Methods for using the same are also disclosed.
• Peroxyacetic acid is known for its antimicrobial properties and its use as an antimicrobial agent is disclosed in U.S. Patent Nos. 5,368,749, 5,494,588, 5,624,575, 5,658,467, and 5,670,055. Disclosed is also synergistic mixtures of peroxyacetic acid and certain biocides as well as methods of using the same.
• THPS tetrakis (hydroxy methyl) phosphonium sulfate
• the phrases “antimicrobial”, “biocide”, and “inhibiting microbial growth” refer to the killing of, the inhibition of, or the control of the growth of bacteria, yeast, mold and/or algae.
• a number of important industries have experienced serious adverse effects from the activity of such biological growth on the raw materials which they employ, in their process waters, on various components of their manufacturing processes, and in the finished products which they produce.
• Such industries include the paint, wood, textile, cosmetic, leather, tobacco, fur, rope, paper, pulp, plastics, fuel, oil, rubber, and machine industries.
• Slime control in papermaking processes is of particular importance.
• the control of bacteria and fungi in pulp and paper mill water systems which contain aqueous dispersions of papermaking fibers in various consistencies is especially critical.
• the uncontrolled buildup of slime produced by the accumulation of bacteria and fungi may cause off-grade production, decreased production due to down-time and greater cleanup frequency, increased raw material usage, and increased maintenance costs.
• the problem of slime deposits is especially critical in light of the widespread use of closed white water systems in the paper industry.
• clay and pigment slurries comprise various clays (e.g., kaolin) and pigments (e.g., calcium carbonate and titanium dioxide) and usually are manufactured at a location separate from the end use application. This means that they are generally transported and stored for later use at the application site. Because of high quality standards for the paper and paint products in which such slurries are used, it is essential that these clay or pigment slurries have a very low microorganism count per gram of sample.
• clays e.g., kaolin
• pigments e.g., calcium carbonate and titanium dioxide
• the synergistic antimicrobial combination comprises an effective amount of peroxyacetic acid (PAA) and an effective amount of a phosphorus compound selected from the group consisting of tetrakis (hydroxy methyl) phosphonium sulfate (THPS), tetrakis (hydroxy methyl) phosphonium phosphate (THPP), and tetrakis (hydroxy methyl) phosphonium chloride (THPC).
• PAA and phosphorus compound can be any amount that provides an antimicrobial effect.
• this amount is an amount that, even if added in much higher amounts to the system, results in a synergy index (K value) of less than 1 after partial biocide degradation.
• the synergistic antimicrobial combination according to the present invention can also comprise: a) PAA and b) a phosphorus compound selected from the group consisting of THPS, THPP, and THPC, wherein the weight ratio of a) to b), on an active basis, ranges between about 1000: 1 and 1 : 1000.
• the synergistic antimicrobial combination according to the present invention can also be in an aqueous concentrate that comprises: a) about 0.0001 to about 0.1 weight % PAA; b) about 0.0001 to about 0.1 weight % of a phosphorus compound selected from the group consisting of THPS, THPP, and THPC; and c) the remainder being water (and other raw materials of the system being treated); wherein the weight ratio of a) to b), on an active basis, ranges between about 1000:1 and 1 : 1000.
• the present invention also provides a method for inhibiting microbial growth in aqueous systems and on articles of manufacture prone to such growth comprising adding to said systems or applying to said articles an effective amount the synergistic antimicrobial combinations above.
• the combination of PAA and the phosphorus compound is a synergistic antimicrobial combination, in that this combination generally meets the described antimicrobial needs for many applications.
• This synergistic combination is of even more value because of the desire in some industries to avoid the use of halogens to lessen the risk of adverse impact upon the environment.
• the term "effective amount” refers to that amount of a composition comprising PAA and the phosphorus compound necessary to achieve the desired level of inhibition or control of microbial growth in the aqueous system or on the article being treated.
• the phosphorus compound used in the synergistic blend of the present invention is disclosed in U.S. Patent No. 4,673,509, the disclosure of which is incorporated herein by reference in its entirety.
• the phosphorus compound is preferably selected from the group consisting of THPS, THPP, and THPC, with THPS being most preferred. THPS is most preferred due to proven efficacy and availability, along with the fact that it is not a halogenated biocide.
• synergistic admixture of PAA and the phosphorus compound, as disclosed herein, and the methods for using the same will be useful in virtually any aqueous system or on any article or product of manufacture in which inhibition of microbial growth is desired, absent compatibility problems.
• Suggested applications of the synergistic antimicrobial combinations of the present invention include, for example: inhibiting the growth of bacteria and fungi in aqueous paints, adhesives, latex emulsions, inks, joint cements and caulking compounds; preserving wood; preserving cutting oils and metal working fluids; controlling slime-producing bacteria and fungi, including yeast and mold, in pulp and paper mills and cooling towers; as a spray or dip treatment for textiles and leather to prevent mold growth; as a component of anti-fouling paints to prevent adherence of fouling organisms; protecting paint films, especially exterior paints, from attack by fungi which occurs during weathering of the paint film; protecting processing equipment from slime deposits during manufacture of cane and beet sugar, food, foodstuffs and food additives; preventing microorganism buildup and deposits in air washer or scrubber systems and in industrial fresh water supply systems; controlling microorganism contamination in closed loop and recirculating water cooling systems; controlling microorganism contamination and deposits in oil field drilling
• the synergistic antimicrobial composition disclosed in the present invention is particularly applicable to microbial slime control in papermaking processes.
• the need to control bacteria and fungi in pulp and paper mill water systems which contain aqueous dispersions of papermaking fibers in various consistencies is disclosed above.
• Another important area in which the antimicrobial compositions of the present invention are particularly useful is in the control of bacterial and fungal growth in clay and pigment slurries, as disclosed above. It is essential that these clay or pigment slurries have a very low microorganism count per gram sample.
• aqueous systems that have a need for the use of the present invention to control microorganisms include cooling waters used in the chemical industry and in power generation, wastewater treatment from municipal and industrial plants, as well as pasteurization systems in the food and beverage industry.
• any system which utilizes circulating water or aqueous media becomes infected with microorganisms and experience substantial impairment of their efficiency when deposits of the microorganisms build up in the system and can be treated according to the present invention.
• Control of microorganisms by the present invention in aqueous media is particularly important where there are dispersed particles or fines in the aqueous media, for example, dispersed cellulosic fibers and dispersed fillers and pigments in papermaking, and dispersed pigments in paint manufacture.
• the present invention is directed to a synergistic antimicrobial composition
• a synergistic antimicrobial composition comprising: a) PAA; and b) a phosphorus compound selected from the group consisting of THPS, THPP, and THPC, wherein the weight ratio of a) to b), on an active basis, preferably ranges from about 1000:1 to 1 :1000.
• the present invention is further directed to a method for inhibiting microbial growth in an aqueous system or on an article of manufacture prone to such growth, which method comprises treating said system or said article with an effective amount of an antimicrobial composition comprising: a) PAA; and b) a phosphorus compound selected from the group consisting of THPS, THPP, and THPC, wherein the weight ratio of a) to b), on an active basis, ranges from about 1000:1 to 1 :1000.
• the weight ratios of the two components of the synergistic combination are dictated by the dosage levels of each component which demonstrate synergism, based on 100% active ingredient, relative to each end use application.
• the weight ratio of component a), PAA, and component b), the phosphorus compound ranges from about 1000:1 to 1 :1000 on an active basis, preferably from about 100:1 to 1 :100, more preferably from about 10:1 to 1 :10.
• the synergistic weight ratio of the two components generally varies to some extent depending on the application and the organism being controlled.
• PAA/phosphorus compound composition has been found particularly effective against bacteria when used in a weight ratio of between about 5:1 to 1 :5.
• the amount of each biocide present can range from about 0.05 parts per million (ppm) to about 200 ppm. Preferably, between about 1 ppm and about 100 ppm of each biocide based on the weight of water in the system being treated, are added, more preferably, between about 2 ppm and 60 ppm.
• an effective amount of the synergistic combination of the present invention must be added to the aqueous system being treated even if there is only a very small amount of one biocide and a larger amount of the other.
• This amount of the synergistic composition of the present invention should at least be about 0.1 ppm based on the weight of water in the system being treated, preferably at least 1 ppm, more preferably at least 10 ppm.
• the upper limits of each component and the upper limits of the total synergistic combination of the present invention depends upon economics and environmental concerns.
• the total amount of the inventive synergistic biocide combination present in an aqueous system should be less that about 300 ppm, preferably less that about 200 ppm, more preferably no more than about 150 ppm, with an amount no more than about 100 ppm being most preferred.
• each biocide in the blend could be present in a concentration ranging from about 0.05 ppm up to as high as 1000 ppm.
• one of the two biocides in the present biocide blend is added at a relatively high concentration (e.g. 200 ppm or more) there still is a synergistic effect at the addition of the second biocide but that effect is masked by the overall high concentration of the total biocide present in the system.
• a relatively high concentration e.g. 200 ppm or more
• the kill rate would be faster than with THPS alone.
• the final kill or inhibition effect would not be significantly different because all of the E.coli bacteria are eventually killed with 200 ppm of THPS all by itself.
• An effective amount of a synergistic combination of PAA and the phosphorus compound can also be applied to the article of manufacture being treated.
• a solution of the synergistic antimicrobial combination described above having a concentration of at least 0.1 ppm is incorporated into, sprayed or poured onto, used to dip, or otherwise applied, for example by dipping or submersing, to the substrate being treated in order to prevent growth of bacteria, mold, yeast and algae.
• the active ingredients of the synergistic antimicrobial compositions of the present invention may also be used in diverse formulations: solid, including finely divided powders and granular materials; as well as liquid, such as solutions, emulsions, suspensions, concentrates, emulsifiable concentrates, slurries and the like, depending upon the application intended, and the formulation media desired.
• synergistic antimicrobial combinations when they are liquid, they may be employed neat or may be incorporated into various formulations, both solid and liquid, as an adsorbate on suitable inert carriers such as talc, clays, diatomaceous earth and the like, or water and various organic liquids such as lower alkanols, kerosene, benzene, toluene, and other petroleum distillate fractions or mixtures thereof.
• suitable inert carriers such as talc, clays, diatomaceous earth and the like, or water and various organic liquids such as lower alkanols, kerosene, benzene, toluene, and other petroleum distillate fractions or mixtures thereof.
• the amount of the synergistic combination of PAA and the phosphorus compound can be added to the aqueous system being treated as solid single components or as a dry blend.
• the synergistic combination is preferably added as a solution that is an aqueous concentration to be diluted in situ to the above amounts.
• This synergistic combination is preferably added as two separate single component solutions to be blended and diluted in situ. This separate addition is preferred due to the instability of blend solution over time due to degradation.
• PAA is an oxidizing biocide and the phosphorus compound is a non-oxidizing biocide.
• PAA degrades in the solution blend as it degrades and oxidizes the phosphorus compound (THPS, THPP, and/or THPC).
• the aqueous concentrate of each of the single component solutions used in the synergistic antimicrobial combination would contain much higher amounts of each of the biocides than would be present in the final treated aqueous system and is well within the ordinary skill of one practicing in the art .
• This concentrate can vary widely depending upon the weight savings desired with reduced amounts of water while maintaining ease of application with minimal mixing in situ. What is important is the ratio and final concentration of each of the biocides in the treated aqueous system. These should be within the limits stated above.
• Each concentrate can contain other standard components and be added in combination with other standard additives used in the particular aqueous system.
• PAA is commercially available in liquid form from English China Clays Inc/Calgon Corporation (ECC/Calgon), Pittsburgh, PA as Metasol ® PAA, which is 12% active PAA, CH3COOOH. This product also contains about 18% hydrogen peroxide, about 20% acetic acid, and about 50% water.
• THPS is also commercially available from ECC/Calgon, Pittsburgh, PA and is in liquid form as Metasol ® LT, which is 35% active THPS in a water solution.
• an effective amount of each active ingredient should be combined in a suitable carrier such as water, organic solvents and the like.
• a suitable carrier such as water, organic solvents and the like.
• synergistic antimicrobial combination disclosed herein may be used in combination with other antimicrobial materials.
• the combination can be combined with other fungicides and bactericides in appropriate concentrations and in appropriate instances so as to combine the action of each to obtain particularly useful results.
• Such combinations might find particular application in the preparation of germicidal soaps, in the production of cosmetics and aqueous coatings and in combating paper mill microbial slime accumulations.
• the synergistic antimicrobial combination of the present invention can be combined with other algicidal agents as well.
• a method of inhibiting the growth of at least one of the following: bacteria, yeast, mold and algae comprising adding to the aqueous system or treating the article or product containing said bacteria, yeast, mold and/or algae with an effective amount of a synergistic combination of PAA and the phosphorus compound (e.g. THPS).
• a synergistic combination of PAA and the phosphorus compound e.g. THPS
• This addition can be accomplished either by simple addition of components together as a single admixture, or by the preferred addition of the two components separately.
• Such separate administration can either be at the same time or at different times. The net effect will be the same—the system, article or product being treated will ultimately have incorporated therein or have applied thereto the desired dosage concentration of each component.
• compositions of the present invention are believed to be effective irrespective of the method of application (unless the blend is stored for a period of time prior to addition).
• the antimicrobial compositions described herein can be added to a system being treated as two separate or one stream via a low level, continuous feed practice, a semi-continuous feed practice or through slug feeding. All of these feeding practices will be familiar to one having ordinary skill in the art. Slug feeding is particularly effective and therefore is a preferred manner of employing the methods of the present invention.
• This type of feed allows the user to monitor the microorganism concentration in the system and feed product only when microorganism concentrations increase. The user realizes a cost savings by feeding an effective amount of PAA and the phosphorus compound only when needed.
• the present invention is based upon the discovery that use of PAA in conjunction with certain types of phosphorus compounds produces synergistic results and is effective in controlling the growth of bacteria, yeast, mold and algae in a variety of industrial and other applications.
• the utility of the synergistic antimicrobial combination disclosed herein derives from its versatility both in the numerous industries in which it can be applied, as well as the numerous microorganisms against which it is effective.
• the large economic losses in papermaking operations caused by the accumulation of bacterial and fungal slimes in various parts of the system can be eliminated to a significant extent by use of the synergistic combination described herein.
• the superior antimicrobial activity of the synergistic antimicrobial combination of PAA and the phosphorus compound has been confirmed using standard laboratory techniques.
• the antimicrobial combination has been found effective, for example, in inhibiting bacterial growth including but not limited to Klebsiella pneumoniae and Escherichia coli and has been found to be particularly effective against Pseudomonas aeruginosa.
• the combination is also believed to be effective against other aerobic bacteria, such as Bacillus, Staphylococcus, Flavobacterium, Enterobacter, and Xanthomonas, anaerobic bacteria, freshwater organisms such as filamentous bacteria, fungi including but not limited to various species of Candida and Saccharomyces, white and pink yeasts, molds, and various species of green algae and blue green algae.
• aerobic bacteria such as Bacillus, Staphylococcus, Flavobacterium, Enterobacter, and Xanthomonas
• anaerobic bacteria such as Bacillus, Staphylococcus, Flavobacterium, Enterobacter, and Xanthomonas
• anaerobic bacteria freshwater organisms
• freshwater organisms such as filamentous bacteria
• fungi including but not limited to various species of Candida and Saccharomyces, white and pink yeasts, molds, and various species of green algae and blue green algae.
• EXAMPLE I The biocidal efficacy in microtiter tests of the antimicrobial composition of the present invention is demonstrated below. Three different bacterial strains, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, as well as a mixture of all three of the strains, were used.
• Each of the three bacteria were separately grown on Standard Methods Agar (STM) plates and incubated at 37°C for a period of between about 24-48 hours.
• STM Standard Methods Agar
• Each species of bacteria was inoculated into a small tissue flask containing approximately 25 ml of Allen's Media using a sterile swab.
• the cultures were then diluted by adding 10 ml of bacterial suspension to 90 ml of fresh Allen's Media.
• To prepare a mixed culture of all three of the organisms an equal amount of approximately 20 ml, of each of the diluted cultures was mixed together in a large tissue culture flask. Samples from the mixture and the individual bacterial suspensions were then used in the microtiter test.
• An 8X stock solution of PAA to use in combination with THPS was prepared by dissolving about 6.6 grams (g) of 12%) active PAA in about 100 ml of deionized water.
• a 4X stock solution of THPS to use in combination with PAA was prepared in the same manner only using 0.106 g of THPS (35% active THPS).
• a 4X stock solution of THPS to use alone was prepared in the same manner only using 0.53 g of THPS.
• a PAA 8X stock solution to use in combination with THPS was prepared by dissolving about 6.6 g of 12%) active PAA in 100 ml with deionized water.
• a 4X stock solution of THPS to use in combination with PAA was prepared in the same manner only using 0.05 g THPS.
• the 4x stock solution of PAA to use alone was prepared in the same manner only using 3.3 g
• the amount of PAA in the wells of plates 1 through 9 were varied in a serial dilution series ranging from 1000 ppm active to 2 ppm active while the other component's (THPS) concentration was kept constant at 200, 100, 300, 500, and 0 ppm active.
• Plate 10 represented use of THPS alone in a serial dilution series.
• Plates 9 and 10 represented the use of each biocide alone and were used to determine the minimum amount of each biocide which, when used alone, would inhibit microbial growth.
• No biocide was added to the wells of column 12 in any of the plates, which represented an organism control, or positive control. This positive control was run to ensure that the organisms were capable of growing in the environment provided.
• Plates 1-4 were used to determine the minimum inhibitory concentration (MIC) for each biocide combination against each bacteria strain.
• the MIC is the least amount of biocide needed to prevent growth in the well, with growth being defined as a turbidity in the medium or a "pellet" of cells which came out of the medium and settled at the bottom of the well.
• Plates 5-8 were then subcultured from plates 1-4, respectively, at 24 hours following biocide addition. Subculturing was done to determine the minimum biocidal concentration (MBC).
• MBC biocidal concentration
• microtiter plates including the MIC plates and the MBC plates were incubated for 24 hours at 37°C. Following the 24 hour incubation period, the presence or absence of growth in each well of the plates was determined. Growth in the microtiter plates was determined by subculturing the plates onto a solid agar plate dipicting each microtiter well. The plates were then incubated at 37°C for 24 hours. The presence or absence of growth in each well, along with the concentration of biocide in each well, was then used to determine the synergistic properties of the biocide combinations. The synergistic properties were evaluated by determining the Kull value/K value; the K value was determined for each bacterium tested. The method for calculating K value is well known to those skilled in the art. In this example, the K value was determined by the following formula:
• [PAA] In Combination means the concentration of PAA which, when used in combination with THPS, resulted in inhibition of microbial growth;
• [THPS] In Combination means the concentration of THPS which, when used in combination with PAA, resulted in inhibition of microbial growth
• [PAA] Alone means the concentration of the PAA which, when used alone, resulted in inhibition of microbial growth
• [THPS] Alone means the concentration of THPS which, when used alone, resulted in inhibition of microbial growth.
• a K value of less than 1 indicates synergy between the two biocides, a K value of greater than 1 indicates antagonism between the two biocides, and a K value equal to 1 indicates an additive effect of the two biocides.

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• Life Sciences & Earth Sciences (AREA)
• Agronomy & Crop Science (AREA)
• Pest Control & Pesticides (AREA)
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• 1999
  • 1999-07-20 CN CN99810033A patent/CN1313728A/zh active Pending
  • 1999-07-20 JP JP2000560781A patent/JP2002521313A/ja active Pending
  • 1999-07-20 EP EP99934161A patent/EP1098566A1/en not_active Withdrawn
  • 1999-07-20 WO PCT/US1999/016463 patent/WO2000004777A1/en not_active Application Discontinuation
  • 1999-07-20 CA CA002337953A patent/CA2337953A1/en not_active Abandoned
  • 1999-07-20 KR KR1020017001031A patent/KR20010079559A/ko not_active Application Discontinuation
  • 1999-07-20 AU AU50053/99A patent/AU5005399A/en not_active Abandoned
  • 1999-07-20 ID IDW20010178A patent/ID27376A/id unknown
  • 1999-07-20 BR BR9912341-0A patent/BR9912341A/pt not_active Application Discontinuation
• 2001
  • 2001-01-19 NO NO20010317A patent/NO20010317L/no not_active Application Discontinuation

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