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PatentsPATENT NUMBER 3,996,378
Abstract Products and processes of a water-based formulation of methylene bis thiocyanate (MBT) in a xanthan gel, which is a hydrophilic colloid in water where the colloid is utilized at a concentration of about 0.02-2.0 weight percent and preferably 0.1-1.0 of the colloid carrier. In use in water treatment, this dosage is adjusted so that use dosage contains about 2-1000 ppm by weight of the microbicide and preferably 20-200 ppm. Alternatively, a ternary formulation may be used containing methylene bis thiocyanate plus an auxiliary fast-acting biocide in the same xanthan gel. The auxiliary microbicide is selected from an n-alkyl (C.sub.12 -C.sub.18) dimethyl(benzyl)ammonium chloride such as the preferred quaternary; i.e., tetradecyl benzyl dimethyl ammonium chloride (ROCCAL-MC-14--Hilton-Davis). The methylene bis thiocyanate or combination of microbicides is utilized for shipment or make up concentration in a weight percentile of 5-20%; a preferred percentile of 5-10%; and an optimum percentile of about 10%, based upon the xanthan carrier in water. The critical microbicide particle size, which is slightly greater than colloidal, is in the broad range 0.8-150 microns, with a preferred average particle size of 1-45 microns.
References Cited [Referenced By] U.S. Patent Documents
Primary Examiner: Turner; V. D. Attorney, Agent or Firm: Premo; John G., Roberts; John S.
The present formulations, as opposed to those containing methylene bis
thiocyanate and an organic carrier or diluent for use, are water-based
formulations of methylene bis thiocyanate which comprise small methylene
bis thiocyanate particles in a range of about 0.8-150 microns in a
xanthan gel wherein the weight percent in methylene bis thiocyanate in
shipment is 5-20 and preferably 5-10 and an optimum of about 10% of the
xanthan gum or gel. In use the dosage is adjusted so that about 2-1000
ppm by weight of the microbicide is actually used in water treatment,
and preferably 20-200 ppm. These formulations also may encompass the use
of a fast-acting auxiliary biocide or slimicide which is a quaternary
compound and specifically is a long chain (C.sub.12 -C.sub.18) dimethyl
benzyl ammonium chloride, such as ROCCAL MC-14 (Hilton-Davis) where C =
14 in the formula above. To the water-based formulation of xanthan which
contains 0.02-2.0% by weight of xanthan hydrophilic colloid is added
methylene bis thiocyanate or methylene bis thiocyanate plus the
quaternary. The colloid in water may be viewed as an aqueous carrier and
the combination is a thick suspension.
It has been long known that methylene bis thiocyanate formulations break down into degradation products which release HCN. It has been found that in the present water-based formulations there is less cyanide release than in those where methylene bis thiocyanate is used with an organic carrier. METHYLENE BIS THIOCYANATE During the past decade the compound methylene bis thiocyanate proved commercially popular and successful for water-treatment purposes and this is the subject of many patents, a sampling of which is noted above. Objections have been raised, however, due to the fact that the shipment and treatment carriers for methylene bis thiocyanate have in some cases proved troublesome due to toxicity and flammability. In addition, where specialized uses involving microbial-contaminated bodies of water which may be natural or artificial and flowing as in cooling towers, the relatively slow-acting nature of methylene bis thiocyanate as a microbicide has posed some problems. In order to eliminate organic diluents such as benzene, toluene, and xylene, which are commercially popular but toxic as well as flammable, the present invention proposes a different solution. In this invention a water-based formulation is utilized and in order to disperse the methylene bis thiocyanate particles in the preferred carrier, the particles are reduced in size to a range with a broad average particle size of 0.8-150 microns and a preferred average particle size of 1-45 microns. THE QUATERNARY To counteract the relative slow action of methylene bis thiocyanate, an additive microbicide is utilized in the ternary forms of the present invention. This auxiliary microbicide is a fast-acting slimicide or bactericide which is selected from a long chain (C.sub.12 -C.sub.18) dimethyl benzyl ammonium chloride. A specific preferred auxiliary microbicide is tetradecyl benzyl dimethyl ammonium chloride (ROCCAL-MC-14 -- Hilton-Davis, Cincinnati, Ohio). This auxiliary agent is compatible with methylene bis thiocyanate and when the combination microbicide is utilized, the dosage concentration is selected so that the amount of quaternary utilized substitutes for a portion of the methylene bis thiocyanate as described above. Since the activity of the quaternary against many common microorganisms is roughly equivalent to methylene bis thiocyanate, this substitution is convenient and facile. The weight percent relationship of methylene bis thiocyanate:quaternary may be within the ranges of 10:1 to 1:10 and a preferred formulation utilizes a relation of 2:1 of methylene bis thiocyanate to quaternary. ROCCAL-MC-14 has a broad range germicidal action and has been found effective against the following representative microbial agents: Enterobacter aerogenes, Escherichia coli, Salmonella typhosa, Salmonella choleraesuis, Salmonella schottmuelleri, Pseudomonas aeruginosa, Shigella dysenteriae, Staphylococcus aureus, and Streptococcus faecalis.
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