Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1999-06-29
2002-10-29
Travers, Russell (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S661000, C424S665000, C424S703000, C252S187250, C514S389000
Reexamination Certificate
active
06471974
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to antimicrobial cleaning solutions, and to methods of making and using such solutions. In more detail, this invention relates to N-chlorosulfamate compositions having enhanced antimicrobial efficacy, and to methods of making and using such compositions.
2. Related Background Art
Although hypochlorite and hypochlorous acid solutions are highly effective antimicrobial agents, they also are highly reactive, chemically aggressive, and unstable solutions. As such, they are not good candidates for inclusion in antimicrobial cleaning solutions. Consequently, efforts have been made to develop more stable and user-friendly forms of hypochlorite and/or hypochlorous acid solutions. Generally, this has been accomplished by the generation of various N-chloro compounds (herein also referred to as stabilized hypochlorite solutions or stabilized hypochlorite species), by reaction of hypochlorite sources with various amines and amides. By the term “stable” or “stabilized” we mean a compound, solution or species in which the active ingredient does not degrade over a substantial period of time.
For example, U.S. Pat. No. 2,438,781 discloses a process for stabilizing alkali-metal hypochlorite solutions by the addition of a stabilizing agent such as benzene sulfonamide, benzene N-sodium sulfonamide or p-toluene sulfonamide. That patent also notes that the use of the disclosed stabilizing agents increases the germicidal activity of the hypochlorite solutions to which they are added.
Aqueous stabilized hypochlorite solutions, such as N-chlorosulfamate solutions, are also known. For example, U.S. Pat. No. 3,170,883 teaches the stabilization of chlorine solutions (e.g., yielding the hypochlorite ion) with the sulfamate ion in concentrations as low as 0.4 ppm with total available chlorine sufficient to give a free available chlorine in a lethal range of 0.2 ppm and more. The created stabilized chlorine solution is recommended for use in cooling towers. In addition, U.S. Pat. No. 3,177,111 teaches a process of bleaching cellulosic materials, particularly wood pulps, with an agent such as N-chlorosulfamic acid and N,N-dichlorosulfamic acid derived from an inorganic hypochlorite and sulfamic acid. The use of sulfamic acid with hypochlorite is said to reduce the amount of hypochlorite required to attain a predetermined level of bleaching by 40-80% of that otherwise required. It also allows the bleaching operation to be carried out at a pH substantially lower than normal and yields a pulp of materially higher viscosity and strength. U.S. Pat. No. 3,749,672 teaches a method of making stable aqueous systems of N-halo compounds, in which the N-halo compounds are formed by mixing an N-hydrogen compound (e.g., sulfamic acid, sulfamide, dimethylhydantoin) with NaOCl or NaOBr. The aqueous system is stabilized by including a buffer that maintains the pH of the system between 4 and 11. U.S. Pat. No. 3,767,586 similarly concerns a process of preparing stable solutions of N-halo compounds by reaction of an N-hydrogen compound, preferably sulfamic acid, in the presence of hydroxides.
Stabilized hypochlorite solutions such as N-chlorosulfamate solutions are also known to possess antimicrobial activity. For example, in U.S. Pat. Nos. 3,749,672 and 3,767,586, the processes are said to produce solutions that are useful for bleaching and for controlling micro-organisms in process streams. Furthermore, U.S. Pat. No. 3,328,294 discusses the preparation and use of N-chlorosulfamate solutions to control microbial organisms in aqueous process streams.
N-chlorosulfamate solutions, however, have not been considered highly desirable as biocidal or disinfecting agents in areas of human contact, for example, in swimming pools, which require rapid microbial elimination. This is due to their weak antimicrobial activity relative to other hypochlorite-containing compounds such as NaOCl, HOCl, chlorinated isocyanuric acids (e.g., trichloroisocyanuric acid and sodium dichloroisocyanurate), and chlorinated hydantoins (e.g., 1,3-dichloro-5,5-dimethylhydantoin). (See, for example: J. E. Delaney and J. C. Morris,
Bactericidal Properties of Chlorosulfamates,
Journal of the Sanitary Engineering Division-Proceedings of the American Society of Civil Engineers, 98 (SA1), 23-36; L. S. Stuart and L. F. Ortenzio,
Swimming Pool Chlorine Stabilizers,
Soap and Chemical Specialties, August (1964); and L. F. Ortenzio and L. S. Stuart,
A Standard Test for Efficacy of Germicides and Acceptability of Residual Disinfecting Activity in Swimming Pool Water,
Journal of the A.O.A.C., 47, 540-547 (1964).) This is unfortunate because N-chlorosulfamate solutions not only are highly stable, but also have a pH that is near the neutral range. Solutions having a pH near the neutral range are highly desirable due to their reduced tendency to cause human irritation and property damage when used.
Finally, U.S. Pat. No. 5,565,109 teaches that certain N-hydrogen compounds (e.g., dimethylhydantoin, methylhydantoin, cyanuric acid, succinimide, and glycoluril) and their chlorinated derivatives can dramatically improve the bactericidal efficacy of hypochlorite solutions in pulp slurries, presumably by increasing the lifespan of the active chlorine. According to the '109 patent, the addition of dimethylhydantoin to sodium hypochlorite solutions enhances the biocidal activity of sodium hypochlorite, and the activity of hydantoins are greater than sulfamic acid and similar to cyanuric acid.
However, hypochlorite solutions stabilized with sulfamic acid or sulfamate exhibit superior long-term chemical stability in comparison to hypochlorite solutions stabilized with 5,5-dialkyl hydantoin or isocyanuric acid derived compounds. In addition, stabilized hypochlorite solutions containing alkyl hydantoin or cyanuric acid compounds usually are formulated as a suspension or slurry due to the lack of the solubility of the named N-chloro compounds in the hypochlorite-containing composition. In contrast, stabilized hypochlorite solutions containing sulfamic acid typically remain as a homogeneous (single-phase) solution. Homogeneous (single-phase) solutions are preferred by consumers and thus are more commercially viable.
Consequently, there is a need for an enhanced antimicrobial solution that can be used in various applications, including household cleaners, process streams and cooling towers. In particular, it would be useful to have a highly effective antimicrobial solution that not only is a stable, ready-to-use solution that does not give off annoying chlorine fumes, but also is a solution that is “user friendly” due to its mildly acid to near-neutral pH.
SUMMARY OF THE INVENTION
Surprisingly, we have found that hypochlorite solutions stabilized by the addition of sulfamate and additionally containing certain organoamide dopants possess enhanced antimicrobial activity relative to the initial sulfamate-only stabilized hypochlorite solution. This is an unexpected result due to the known lack of antimicrobial effectiveness of hypochlorite solutions stabilized with sulfamate.
Specifically, in one aspect, we have invented an antimicrobial solution comprising: a stabilized hypochlorite solution consisting essentially of a buffered aqueous combination of mono-N-chlorosulfamate (HClNSO
3
−
) and di-N-chlorosulfamate (Cl
2
NSO
3
−
); and at least a dopant selected from the group consisting of a dialkyl hydantoin, preferably 5,5-dialkyl hydantoins, (e.g., 5,5-dimethylhydantoin, 5-ethyl-5-methylhydantoin, or 5,5-diethylhydantoin), an aryl sulfonamide (e.g., benzene sulfonamide, toluene sulfonamide, 4-carboxybenzensulfonamide), a succinimide and a glycoluril. The stabilized hypochlorite solution enhanced with a dopant has a pH between about 2 and about 10, preferably between about 2 and about 7, and most preferably between about 3 and about 6.
In another aspect, our invention also provides a stabilized hypochlorite solution having enhanced antimicrobial properties comprising: a hypochlorite stabilized
Hilgers Debra S.
Rees Wayne M.
S.C. Johnson & Son Inc.
Travers Russell
Wang Shengjun
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