Cleaning and liquid contact with solids – Processes – Work handled in bulk or groups
Reexamination Certificate
2001-07-30
2003-03-11
Gupta, Yogendra N. (Department: 1751)
Cleaning and liquid contact with solids
Processes
Work handled in bulk or groups
C134S025400, C134S042000, C510S199000, C510S319000, C510S384000, C510S391000, C510S423000, C510S433000, C510S504000, C510S240000
Reexamination Certificate
active
06530384
ABSTRACT:
TECHNICAL FIELD
This invention relates to novel chemical formulations useful for simultaneous cleaning and disinfecting surfaces, especially porous surfaces, such as acoustic ceiling tiles in hospitals and other medical and dental facilities, etc., where at least a virtual 100% kill rate of bacteria and fungi is desired. More particularly, the present invention relates to potentiated disinfectant cleaning solutions comprising as active working ingredients a quaternary ammonium compound, a compatible surfactant other than a quaternary ammonium compound, such as a non-ionic or amphoteric surface active agent, and a solution of hydrogen peroxide. The active ingredients are present in minimal proportional ranges sufficient to achieve a virtual 100 percent kill of the microbes, e.g., bacteria and fungi present.
Furthermore, the invention relates to processes of disinfecting contaminated surfaces/substrates with the foregoing anti-microbial cleaning solutions wherein virtually 100% of bacteria and fungi are destroyed, resulting in the restoration and extension of the useful life of the treated surfaces/substrates.
BACKGROUND OF THE INVENTION
Disinfection of building interiors and other surfaces is a major concern in hospitals and other health care facilities where the presence of unwanted bacteria may be detrimental to the health of patients and workers. Health care facilities are not alone in their concern for elimination of harmful bacteria and fungi. Surfaces harboring undesirable microorganisms can pose a health threat in schools, office buildings and homes. For that reason, it is highly desirable to disinfect all surfaces in such facilities to remove as many harmful organisms as possible.
A common building surface of particular concern is ceiling tiles. Because of their porosity, ceiling tiles are particularly susceptible to harboring harmful bacteria and other microorganisms, and they are especially difficult to clean. In many instances, cleaning and disinfecting the tiles involves removing the tiles and exposing them to time consuming treatments with bactericidal agents. Even after such treatment significant amounts of bacteria and fungi can remain in the tiles and replicate.
Cleaning compositions exist which can achieve high kill rates of some harmful microorganisms. However, these compositions tend to have relatively high concentrations of toxic ingredients. Safe application of these compositions often requires special handling procedures and precautions. These can include use of protective equipment, such as safety goggles, gloves, coveralls, face masks, and the like. In many cases, additional ventilation of the space being disinfected is essential during and after application of these compositions.
Hydrogen peroxide (H
2
O
2
) has been proposed as a bactericide and has been used for many years as a topical antiseptic, especially as a 3% aqueous solution. Addition of ferric or cupric ions, potassium dichromate, cobaltous sulfate, or manganous sulfate is known to enhance the bactericidal action of H
2
O
2
.
However, H
2
O
2
suffers from the disadvantage that by itself it is relatively inefficient and is not a potent fungicide. Further, H
2
O
2
especially at higher concentrations is irritating to the skin, eyes, and mucous membranes. Health and safety hazards associated with the use of solutions containing H
2
O
2
increase as the concentration of H
2
O
2
in the solutions increases. It is therefore desirable that disinfecting solutions contain the lowest possible concentrations of H
2
O
2
.
Processes and compositions for the disinfection of aqueous media employing hydrogen peroxide are disclosed in U.S. Pat. No. 4,311,598 to Verachtert. The disinfectant comprises a combination of hydrogen peroxide, a soluble copper salt, such as copper sulphate and an autoxisable reducing agent such as ascorbic acid or sodium sulphite. While these compositions appear to be relatively effective in killing bacteria in some aqueous solutions, they are not efficacious fungicides. Nor has their efficacy on surfaces been demonstrated.
Quaternary ammonium compounds, usually tetrasubstituted ammonium salts, have been reported for use as bacteristats, bactericides, and algaecides. Those used as bacteristats and bactericides have required relatively high levels to be effective or have required prolonged contact times.
Examples of references describing the use of quaternary ammonium compounds include U.S. Pat. No. 5,373,025 to Gay which discloses a sanitizer for swimming pools, spas and hot tubs comprising a quaternary ammonium compound and a copper ion source.
Examples of publications disclosing sanitizers combining peroxides with quaternary ammonium compounds include U.S. Pat. No. 5,348,556 to Minns et al. This patent discloses an aqueous composition which cleans and sanitizes carpets, and the like. In general, the compositions contain peroxide in concentrations of about 3% to about 30%, in combination with a volatile ammoniated substance, including tetra butyl ammonium hydroxide, in an amount of about 0.1% to 5%. However, the Minns et al patent does not disclose a fungicide, nor are the compositions disclosed as providing at least a virtual 100% kill rate of bacteria.
U.S. Pat. No. 4,397,757 to Bright et al discloses bleaching and detergent compositions containing hydrogen peroxide and quaternary ammonium activators. While the compositions of the Bright et al patent are disclosed to be effective as whiteners and cleaners, such compositions are not intended to provide high kill rates of bacteria and fungi.
Other patents of interest employing quaternary ammonium compounds are U.S. Pat. Nos. 4,941,989 and 5,320,805 both to Kramer et al. Each of the Kramer patents discloses a variety of compositions, all characterized as prepared from alkaline water soluble “per salts”, preferably from 10 to 90% by weight sodium percarbonate (2Na
2
CO
3
.3H
2
O
2
); from a fraction of a percent to about 30% by weight of a positively charged phase transfer agent, preferably a quaternary ammonium salt, and a surfactant within a range of about 0.25 to 20% by weight.
According to the Kramer et al patents, the alkaline per salt is dissolved in an aqueous solution of the positively charged quaternary ammonium phase transfer agent to extract a proton from the per salt. According to the express teachings of Kramer et al, in order for the reaction to occur the aqueous medium is required to have a rather high pH of at least 9.5. This high pH is readily attained because per salts, such as sodium percarbonate also yield alkaline sodium carbonate when in water. Such aqueous compositions will typically have pHs in the range of 10 to 11, or more.
While such solutions, according to the Kramer patents, yield hydroperoxide ions, HO
2
−
, to become associated with the positively charged quarternary ammonium ion, it was found that any residual molecular hydrogen peroxide which might otherwise remain in the alkaline solution rapidly breaks down as observed by the prompt release of oxygen bubbles.
Accordingly, the instability of hydrogen peroxide when present in alkaline media severally limits shelf-life and the ability to premix antimicrobial solutions with per salts, like sodium percarbonate (Kramer at al), and be able to store and ship product, and maintain high antimicrobial activity.
As previously pointed out, the patents of Kramer et al disclose various types of compositions prepared with per salts, etc., including creams, bulk powders, tablets, soaps and also solutions. While sodium percarbonate has a listed solubility in water of about 120 gm/L at 20° C. the preparation of true solutions, i.e., liquid having a single phase, according to the protocols of the Kramer et al patents by dissolving the granular/solid sodium percarbonate salt in the liquid components were found not to yield true solutions, i.e. liquid with a single phase. Instead, the liquid yields two distinct phases possibly resulting from incompatibilities with other active ingredients in solution, such as the quaternary ammonium compound or surfactant. Hence, t
Dyster Lyn M.
Meyers Stephen J.
Ellis Howard M.
Gupta Yogendra N.
Mruk Brian P
Nemmer Albert E.
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