CA2000282A1 - Formulation of stable water based suspensions of mixtures oftrihaloalkyl sulfone - Google Patents

Abstract

ABSTRACT

This invention relates to tri halo alkyl sulfone and mixtures of bis(trichloro methyl) sulfone (BTCMS) and an auxiliary biocide such as methylene bis(thiocyanate) (MBT) formulated as a stable suspension in water. The process of formulation comprises adding the BTCMS to water containing a swellable smectite clay, then adding the MBT, a suitable amount of a thickening or stabilizing agent and a surfactant. Preferably, magnesium aluminum silicate is the swellable smectite clay and the thickening agent is xanthan gum or hydroxypropyl methyl cellulose. These formulations are useful as biocides and present advantages over organic solvent based formulations.

Description

FORMULATION OF STABLE WATER BASED SUSPENSIONS
OF MIXTURES OF TRIHALOALKYL SULFONE

This invention relates to the formulation of a stable, water based suspension of trihaloalkyl su~fone. More particularly, the invention relates to the formulation of a stable, water based suspension of bis(trichloromethyl)sulfone (BTCMS) and methylene bis(thiocyanate) (MBT).

Manufacturing as well as production processes use huge quanti~ies of raw as well as potable water that must be treated with biocides in order to assure product and production standards.
Typically, cooling towers, paper and pulp mills, canning industries, animal hide processing plants, secondary oil reGovery using water flooding, industrial water systems, to name a few, require the use and recycling of the water used in these processes. These systems become easily contaminated with microorganisms such as bac~eria, algae, fungi, etc~, due to exposure to contaminants encountered in the process of manufacturing and/or from the products being `
processed. These waters become a breeding media for microorganisms which must be controlled and/or eliminated. Biocides have been developed which conkrol such contaminants which if left unchecked, will destroy equipment and/or reduce the quality of a manufactured product.

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Two chemicals employed as biocides to control the undesirable yrowth of microorganisms are bis trihaloalkyl sulfone and MBT. Formulations containing mixture of these chemicals in organic solvents are known to exhibit superior fungicidal and bactericidal efficacy when compared to formulations containing individual components. For example, U.S. Patent No. 3,426,134 to Shema et al. discloses synergistic blends of these chemicals~ These formulations involve the use of organic solvents. These mixtures are used as slimicides in the production of paper and paperboard as well as biocidal uses in other industries.

However there are growing objections to the use of costly organic solvents in formulating biocides. Of extreme concern is the ecological impact of these organic solvents. The organic solvents typically used, for example dimethylformamide (DMF), are toxic by themselves. In addition, these solvents can accelerate in the ability of a biocide to penetrate human skin, so that in the case of spills or accidental contact, the danger to human life is increased. Other problems posed by utilizing organic solvents are low flash point, hence a fire hazard, and excessive repulsive odors.

Economic problems are a concern when the biocides are formulated using organic solvents. Organic solvents cost more and they can present processing problems so that the effect is to increase the cost of biocidal formulations containing organic solvents.

Recent changes in Environmental Protection Agency (EPA) regulations present additional difficulties by requiring the removal of solvent based products from the marketplace. Action has already . , - - . . ~ .. ..
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been taken by the EPA against DMF. It is anticipated that actionagainst other commonly used solvents for biocide formulations may be taken.

Accordingly, there is a need for alternatives to organic solvent based biocide formulations. It has now been discovered that trihaloalkyl sulfone, specifically bis(trichloromethyl) sulfone and mixtures of bis(trichloromethyl) sulfone and MBT can be formulated as stable suspensions in water. The formulas of the present invention have shown biocidal efficacy essentially equivalent to the solvent based formulas~

These formulas avoid the disadvantages associated with the use of organic solvents. The inventive formulas result in a reduced risk to human life through accidental skin exposure. These novel suspensions can be prepared so as to contain a variety of concentrations of active ingredients. The technique involved readily permits the introduction of other biocides into the product suspension.

As shown by U.S. Patent No. 3,42~,124 to Shema et al~
combinations of trihaloalkyl sulfone, and more specifically bis(tribromomethyl) sulfone (BTBMS) or bis(trichloromethyl) sulfone (BTCMS), and methylene bis thiocyanate (MBT) are useful biocidal compositions for controlling slime forming organisms in the water employed in paper or pulp mills, cooling systems and other industrial water systems.

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Water based formulations of biocidal compositions are also known in the art~ U.S~ Patent 3,996,378 to Payton discloses a water based composition comprising MBT in a xanthan gel and optionally an auxiliary fast-acting biocide. The auxiliary biocide is selected from an n-alkyl (C12 - Clg) dimethyl(benzyl~ ammonium chloride~

U~S. Patent 3,996,155 to Slovinsky et al~ discloses an oil in water emulsion of BTS which can be made from dimethyl sulfide and sodium hypochlorite or aqueous brine~ It is possible to add additional biocides such as biocidal quaternary ammonium compounds9 MBT, and bis(tri-n-butyl tin)oxide to the BTCMS emulsion.

U~S. Patent 4,671,815 to Bellos et al~ discloses the use of oxyalkylated amines which will render biocide actives such as a BTCMS and MBT soluble in water for use as a biocidal composition~ -Description of the Invention In the present invention, it has been discovered that blends comprising trihaloalkyl sulfone, a surfactant(s), a swellable smectile clay, and a suitable thickener can be prepared to form stable dispersions or suspensions in water~ Optionally, a suitable auxiliary biocide such as a water-soluble biocide or methylene bis(thiocyanate) (MBT) may be added to the dispersion or suspension~ These mixtures have shown biocidal efficacy essentially equivalent to the corresponding organic solvent containing formula~

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Q~82 The trihaloalkyl sulfones utilized in the practice of the invention are bis(trichloromethyl) sulfone (BTCMS) and bis(tribromomethyl) sulfone (BTBMS), as disclosed by U.S. Patent 3,426,134. The preferred sulfone is BTCMS.

Surfactants which can be utilized in the practice of ~he present invention include cationic, anionic, and nonionic materials. These surfactants typically have HLB values of between 6 and 30. Examples of suitable anionic surfactants include, but are not limited to, sulfates and sulfonates of the following hydrophobes: alkyl, diphenyl, olefins, alcohols and ethoxylated alcohols; ethoxylated alkyl phenols; fatty esters; oils and fatty acids; alkylaryl, dodecyl and tridecylbenzenes; naphthalene and alkyl naphthalenes; and petroleum derivatives. Examples of suitable nonionic surfactants include, but are not limited to, block polymers of poly(ethylene) and poly(propylene) oxides, ethoxylated alcohols, ethoxylated alkyl phenols, ethoxylated fatty acids, ethoxylated fatty acids and esters, fatty esters, glycerol and glycol esters, and sorbitan esters.

Examples of suitable cationic surfactants include, but are not limited to quaternary ammonium salts such as N,~-dialkyl (Cg to C16) N,N,N-trimethyl-ammonium salts, and N-alkyl, N,N-dimethyl N-benzyl-ammonium chloride.

Preferably, the surfactant is selected from the group consisting of ethoxylated alcohols, ethoxylated alkyl phenols, block polymers of poly(e~hylene) and poly(propylene) oxides, and N-alkyl (40% C12, 50% C14, 10% C16) N,N-dimethyl N-benzyl-ammonium chloride. Most preferrably, the surfactant is a nonylphenoxy polyethoxy ethanol sold by Texaco Chemical Company under the name "Surfonic N-95."

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The clay used in the present invention may be any suitable synthetic or naturally occurring smectite clay which swells when dispersed in water. Optionally, these clay materials may be specially treated. Suitable clays may be generically described as S magnesium aluminum silicates. Specific examples of suitable naturally occurring smectite clays include, but are not limited to, montmorillonite, bentonite, and hectorite. An example of a suitable specially treated clay is available from R. T. Vanderbilt Co., Inc.
under the trademark "Veegum"~

Suitable thickeners used in the practice of the present invention include both synthetic and naturally occurring materials.
Examples of suitable naturally occurring thickeners include, but are not limited to, guar gum, locust bean gum, gum arabic, carrageenin, xanthan, and cellulosics such as methyl cellulose, carboxymethyl cellulose and hydroxypropyl methyl cellulose~ Preferrably the thickener used is hydroxypropyl methyl cellulose.

The auxiliary biocide may be any compa~ible water soluble or water slightly soluble biocide. Exemplary auxiliary biocides include 5-chloro-2-methyl-4-isothiazoline-3 one and 2-methyl-4-isothiazoline-3-one, 2-(decylthio)ethanamine hydrochloride9 3,5 D thiadiazinethione 2,2-dibromo-3-nitrilo propionamide, and dodecylguanidine.

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One method used to make the formulation of the present invention is as follows: -1. In a suitable vessel, add the required water and begin heating to about 85C.

2. Add the required quantity of swellable smectite clay and agitate~

3. Continue heating to about 85C with constant agitation.

4~ Add the required quant;ty of thickener while maintaining about 85C and constant agitation~

5~ Add the surfactant(s) while maintaining constant temperature and mix for about 30 minutes~

6~ Optionally, add an auxilary biocide and mix~

7~ Add the sulfone and mix~

8~ Allow suspension to cool to about 23 to 33C while constantly agitating the suspension.
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Another method of preparing the formulations of the present invention is as follows:

1. Disperse about 1.0 parts (by weight~ of magnesium aluminum silicate in about 78-80 parts (by weight) of water by mixing at about 40 to 50 C for approximately 15 minutes.

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20~82 2. Adjust the pH of the above dispersion to 5.

3. Add about 10 parts (by weight) of BTCMS and mix for about 10 to lS minutes at a temperature range of about 45 to 50 C.

4. Add about 10 parts (by weight) of MBT.

5. Homogenize for about 10 minutes at about 50C.

6. Remove heat and add about 0.20 parts (by weight) of xanthan gum.

7~ Mix for about 20 to 30 minutes.

In accordance with the above procedure the following compositions (A-J) were prepared~ These compositions were tested for biocidal efficacy against Klebsiella pnemoniae at a 20 ppm dosage. The make up of the compositions and the percent kill is described in Table I below. Composition K is a commercially available organic solvent based biocidal composition having MBT and BTCMS as the active ingredients. The surfactant utilized is Surfonic N-95 ~nonylphenoxy polyethoxy ethanol) a product of Texaco Chemical Company. The thickener is hydroxypropyl methyl cellulose.

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Composition Surfactant Thickener MBT BTCMS Clay % Kill 20 ppm S A 15.0% 0 0.0% 20.0% 0.5% 35 B 15.0% 0 0.0% 20.0% 1.5% 66 C 0.5% 0.5 0.0% 20.0% 0.5% 0 D 0.5% 0 0.0% 20.0% 1.5~O 11 E 0.5% 0.5 5.0% 0.0% 0.5% 10 F 0.5% 0 5.0% 0.0% 1.5% 38 G 0.5% 0 5.0% 20.0% 0.5% 16 H 0.5% 0.5 5.0% 20.0% 1.5% 71 I 5.0% 0.5 5.0% 17.5% 1.5% 56 J 5.5% 0.35 6.0% 11.0% 2.0% 99 K 5.0% - 5.0% 17.5% -- 60 Although not as efficacious as oil based formulations, the BTCMS in conjunction with a surfactant, thickener, and clay still represents an advancement in the art by eliminating the need for troublesome organic solvents. ;

Alternatively, addition of about 5 to 10% (by weight) of an organic solvent such as N,N-dimethylformamide (DMF) or a paraffinic solvent to the formulation and mixing in Step 4 of the procedure above will substantially reduce the particle size of the -MBT crystals. Under these circumstances the process of homogenizing of the MBT suspension (Step 5) can be avoided.

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--lo--Typical formulations for MBT and BTCMS which involve the use of organic solvents are about 25% by weight active ingredients and about 70-75% organic solvent. Even the reduction of the amount of organic solvent utilized in the formulation ameliorates the problems of utilizing organic solvent, namely high cost, low flash point, high corrosion of storage and feeding equipment and excessive repulsive odors.

Emulsification of the BTCMS readily occurs at temperatures of about 40 to 50 C and no advantage is found in elevating the temperature above 50C. In fact, higher temperatures are to be avoided due to the possibility of hydrolysis of BTCMS.

While this invention has been described with respect to particular embodi~ents thereof, it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art. The appended claims and this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention.

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Claims (41)

1. A biocidal formulation comprising a water base, stable suspension of:
a) trihalo alkyl sulfone;
b) a swellable smectite clay;
c) a suitable thickening agent; and d) a suitable surfactant.

2. A biocidal formulation as recited in claim 2 further comprising an auxiliary biocidal active ingredient.

3. A biocidal formulation as recited in claim 2 wherein the auxiliary biocidal active ingredient is methylene bis(thiocyanate).

4. A biocidal formulation as recited in claim 2 wherein the auxiliary biocidal active ingredient is a water soluble biocidal active ingredient selected from the group consisting of

5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one, 2-(decylthio)ethanamine hydrochloride, 3,5 D thiazinethione 2,2-dibromo-3-nitrilo propionamide, and dodecylguanidine.

5. A biocidal formulation as recited in claim 1 wherein the trihalo alkyl sulfone is selected from the group consisting of bis(trichloro methyl) sulfone (BTCMS) and bis(tribromo methyl) sulfone (BTBMS).

6. A biocidal formulation as recited in claim 5 wherein the sulfone is BTCMS.

7. A biocidal formulation as recited in claim 1 wherein the swellable smectite clay comprises a magnesium aluminum silicate.

8. A biocidal formulation as described in claim 7 wherein the magnesium aluminum silicate is selected from the group consisting of montmorillonite, bentonite, and hectorite.

9. A biocidal formulation as described in claim 1 wherein the thickening agent is selected from the group consisting of guar gum, locust bean gum, gum arabic, carrageenin, xanthan gum, methylcellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose.

10. A biocidal formulation as described in claim 10 wherein said thickening agent is hydroxypropyl methyl cellulose.

11. A biocidal formulation as described in claim 1 wherein the surfactant is selected from the group consisting of sulfates and sulfonates of the following hydrophobes: alkyl, diphenyl, olefins, alcohols and ethoxylated alcohols; ethoxylated alkyl phenol; fatty esters; oils and fatty acids; alkylaryl, dodecyl and tridecyl benzenes; naphthalene and alkyl napthalenes; petroleum derivatives; block polymers of poly(ethylene) and poly(propylene) oxides; ethoxylated alcohols; ethoxylated fatty acids, ethoxylated fatty acids and esters; glycerol and glycerol esters; and sorbitan esters.

12. A biocidal formulation as described in claim 11 wherein the surfactant is selected from the group consisting of ethoxylated alcohols, ethoxylated alkyl phenols, and block polymers of poly(ethylene) and poly(propylene) oxides.

13. A biocidal formulation as described in claim 12 wherein the surfactant is nonylphenoxy polyethoxy ethanol.

14. A biocidal formulation comprising a water based stable suspension of:

a) about 1% to 25% by weight of a trihaloalkyl sulfone selected from the group consisting of BTCMS and BTBMS;

b) about 0.55 to 3.5% by weight of magnesium aluminum silicate;

c) about 0.1% to 0.5% by weight of a thickener selected from the group consisting of guar gum, locust bean gum, gum arabic, carogeenin xanthan gum, methylcellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose;

d) about 0.5% to 15% by weight of a surfactant selected from the group consisting of ethoxylated alcohols, ethoxylated alkyl phenols and block polymers of poly(ethylene) and poly(propylene) oxides.

15. A biocidal formulation as described in claim 14 wherein said sulfone comprises BTCMS.

16. A biocidal formulation as described in claim 14 wherein said sulfone comprises BTBMS.

17. A biocidal formulation as described in claim 15 further comprising an auxillary biocide selected from the group consisting of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one, 2-(decylthio)ethanamine hydrochloride, 3,5 D thiazinethione 2,2-debromo-3-nitrilo propionamide, and dodecylguanidine.

18. A bicodial formulation as described in claim 15 further comprising about 5% to 6% by weight of MBT.

19. A biocidal formulation as described in claim 18 wherein said thickener is hydroxypropyl methyl cellulose.

20. A biocidal formulation as described in claim 15 wherein said surfactant is nonylphenoxy polyethoxy ethanol.

21. A biocidal formulation as recited in claim 2 further comprising about 5 to 10 parts by weight of an organic solvent selected from the group consisting of N,N-dimethylformamide and paraffinic compounds.

22. A biocidal formulation comprising a stable suspension in water comprised of the following ingredients:
a) about 78-80 parts by weight of water, b) about 1 part by weight of magnesium aluminum silicate, c) about 10 parts by weight of BTCMS, d) about 10 parts by weight of MBT, and e) about 0.2 parts by weight of xanthan gum.

23. A method for formulating a stable suspension in water of trihalo alkyl sulfone (sulfone) comprising:

a) dispersing an effective amount of a swellable smectite clay;

b) adding an effective amount of a compound which will thicken and stabilize the suspension.

c) adding an effective amount of a surfactant and mixing; and d) adding about 1% to 20% by weight of sulfone to the dispersion and mixing.

24. A method as described in claim 23 wherein the sulfone is selected from the group consisting of bis trichloro methyl sulfone (BTCMS) and bis tribromo methyl sulfone (BTBMS).

25. A method as described in claim 24 wherein the thickening agent is selected from the group consisting of guar gum, locust bean gum, gum arabic, carrageenin, xanthan gum, methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose.

26. A method as described in claim 24 wherein the thickening agent is hydroxypropyl methyl cellulose.

27. A method as described in claim 26 wherein the sulfone is BTCMS.

28. A method as described in claim 25 wherein the swellable smectite clay is magnesium aluminum silicate.

29. A method as described in claim 23 wherein the surfactant is selected from the group consisting of sulfates and sulfonates of the following hydrophobes: alkyl, diphenyl, olefins, alcohols and ethoxylated alcohols; ethoxylated alkyl phenols; fatty esters; oils and fatty acids; alkylaryl, dodecyl and tridecyl benzenes napthalene and alkyl naphthalenes; petroleum derivatives;
block polymers of poly(ethylene) and poly(propylene) oxides;
ethoxylated alcohols; ethoxylated fatty acids, ethoxylated fatty acids and esters; glycerol and glycerol esters; and sorbitan esters.

30. A method as described in claim 29 wherein the surfactant is selected from the group consisting of ethoxylated alcohols, ethoxylated alkyl phenols, and block polymers of poly(ethylene) and poly(propylene) oxides.

31. A biocidal formulation as described in claim 30 wherein the surfactant is nonylphenoxy polyethoxy ethanol.

32. A method as described in claim 23 further comprising adding an effective amount of an auxiliary biocide active ingredient selected from the group consisting of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one, 2-(decylthio)ethanamine hydrochloride, 3,5 D thiazinethione 2,2-dibromo-3-nitrilo propionamide, dodecylguanidine, and methylene bis(thiocyanate) (MBT).

33. A method as described in claim 32 wherein the auxiliary biocidal active ingredient is MBT.

34. A method for formulating a stable suspension in water of BTCMS and MBT comprising the steps of:

a) dispersing an effective amount of a swellable smectite, b) adding about 10 parts by weight of BTCMS to the dispersion and mixing, c) adding about 10 parts by weight of MBT and mixing, then, d) adding an effective amount of a compound which will thicken and stabilize the suspension.

35. A method as recited in claim 34 further comprising adding about 5 to 10 parts by weight of an organic solvent selected from the group consisting of N,N-dimethylformamide and paraffinic compounds.

36. A method as described in claim 34 wherein the swellable smectite clay is magnesium aluminum silicate.

37. A method as described in claim 34 wherein the compound to thicken and stabilize the suspension is selected from the group consisting of guar gum, locust bean gum, gum arabic, carrageenin, xanthan gum, methyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose.

38. A method as described in claim 37 wherein the thickening agent is hydroxypropyl methyl cellulose.

39. A method of formulating a stable suspension of a mixture comprised of BTS and MBT in water comprising the steps of :

a) Dispersing about 1.0 part by weight of magnesium aluminum silicate in about 78-80 parts by weight of water by mixing at about 40° to 50° C for approximately 15 minutes, b) adjusting the pH of the above dispersion to 5, c) adding about 10 parts by weight of BTS and mixing for about 10 to 15 minutes at a temperature range of about 45° to 50° C, d) adding about 10 parts by weight of MBT, e) homogenizing for about 10 minutes at about 50° C, f) removing the mixture from the heat and adding about 0.20 parts by weight of xanthan gum, and g) mixing for about 20 to 30 minutes.

40. A method of formulating a stable suspension of a mixture comprised of BTS and MBT in water comprising the steps of:

a) dispersing about 1.0 parts by weight of magnesium aluminum silicate in about 78-80 parts by weight of water by mixing at about 40° to 50° C for approximately 15 minutes, b) adjusting the pH of the above dispersion to 5, c) adding about 10 parts by weight of BTS, and mixing for about 10 to 15 minutes at a temperature range of about 45° to 50° C, d) adding about 10 parts by weight of MBT, and about 5 to 10 parts by weight of an organic solvent selected from group consisting of N,N-dimethyl formamide and paraffinic compounds, e) mixing for about 20 minutes at 50°C, f) removing the mixture from the heat and adding about 0.20 parts by weight of xanthan gum, and g) mixing for about 20 to 30 minutes.

41. A method of controlling microorganisms in an aqueous system easily contaminated with microorganisms comprising treating said system with a biocidally effective amount of a water based stable suspension of BTCMS and MBT as described in claim 33.