Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-08-03
2002-10-22
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S477000, C510S488000, C510S505000
Reexamination Certificate
active
06468953
ABSTRACT:
BACKGROUND OF THE RELEVANT ART
1. Field of the Invention
The present invention relates to anti-microbial solutions and methods of making and using anti-microbial solutions, especially sporicidal solutions.
2. Background of the Invention
Steam autoclaves can be used to sterilize some medical instruments by subjecting the instruments to superheated steam at high pressures before being depressurized and cooled. One of the drawbacks of the steam autoclave is that many medical instruments cannot withstand the high temperatures and pressures. Another drawback resides in the one to two hour cycle time that is required to achieve sterilization.
Ethylene oxide gas can be used to sterilize some other medical instruments and equipment that cannot withstand the pressure or temperature of the autoclave. The instruments are sealed in a sterilizing chamber and pressurized with the ethylene oxide gas. However, ethylene oxide sterilization requires long cycle times and careful handling of the highly toxic ethylene oxide gas. Furthermore, some medical equipment can not be sterilized with ethylene oxide gas.
Liquid sterilization systems can be used to sterilize equipment that cannot withstand either the autoclave or the ethylene oxide gas. These systems involve immersing the equipment into a vat or tank that has been filled with a sterilizing solution, such as stabilized hydrogen peroxide or glutaraldehyde. Because such liquid sterilizations are normally performed manually, the skill and care of the technician are determining factors in whether sterilization or disinfection is, in fact, attained. In many instances, the components of the anti-microbial composition must be mixed by a technician who may become exposed to the harmful vapors produced by many disinfectants, such as glutaraldehyde. Even when mixed properly, immersion times on the order of six to ten hours are commonly required to assure sterilization. Moreover, many liquid sterilization systems are highly corrosive to metal parts, particularly brass, copper, and aluminum. With long immersion times, even the carbon steel and stainless steel of the medical instruments can become pitted and sharp cutting edges dulled.
Antimicrobial compositions are particularly needed in the food and beverage industries to clean and sanitize processing facilities such as pipelines, tanks, mixers, etc. and continuously operating homogenization or pasteurization apparatus. Other uses for antimicrobial compositions include vegetable washing and disinfection, meat surface decontamination, poultry chiller baths, cleaning of electronic components, treatment of wounds, cleaning in place of food processing equipment, cleaning and disinfecting beverage containers, terminal sterilization, treatment of contaminated infectious waste and elimination of odors.
Sanitizing compositions have been formulated in the past to combat microbial growth in such facilities. For example, Wang, U.S. Pat. No. 4,404,040, teaches a short chain fatty acid sanitizing composition comprising an aliphatic short chain fatty acid, a hydrotrope solubilizer capable of solubilizing the fatty acid in both the concentrate and sanitizing solution, and a hydrotrope compatible acid so that the sanitizing solution has a pH in the range of 2.0 to 5.0.
Ozone has long been recognized as a useful chemical commodity valued particularly for its outstanding oxidative activity. In fact, ozone is the fourth strongest oxidizing chemical known, having an oxidation potential of 2.07 volts. Because of this property, ozone and/or fluid mixtures including ozone are capable of removing a wide variety of contaminants, such as cyanides, phenols, iron, manganese, and detergents, from surfaces. Also, ozonated water is used to “clean”, i.e., oxidize, the surface of silicon wafers in-process in the semiconductor industry. Additionally, ozone is also useful for inhibiting, reducing and/or eliminating the accumulation of biomass, mold, mildew, algae, fungi, bacterial growth and scale deposits in various aqueous solution systems. When used in this manner, ozonation provides the advantage of producing a lesser quantity of potentially harmful residues than, e.g., chlorination, which leaves undesirable chlorinated residues in aqueous systems. However, the effectiveness of ozonated water in each of these applications is adversely affected by its low solubility and short-half life (approximately 10 minutes) in aqueous solutions. That is, not only is it difficult to dissolve ozone in an aqueous solution, but also, once dissolved, it is difficult to maintain the ozone in solution.
Ozone has been shown to be inadequate for many medical disinfection and sanitization applications. The disinfection of medical equipment often necessitates use of disinfectants able to deactivate resistant microorganisms, such as bacterial spores. Ozone is a poor sporicidal agent both in the gas phase or dissolved in liquids. This is believed to be due to the slow penetration of ozone through the spore's protective layers. Though this deficiency can be overcome by lengthening the contact time, it is inconvenient and often impractical to do so. Furthermore, ozone does not retain its antimicrobial activity in the presence of interfering compounds, because ozone reacts indiscriminately with dissolved oxidizable substances such that the amount of ozone available for disinfection is drastically reduced.
To counter these limitations, there are several methods of increasing the quantity of dissolved ozone in aqueous solutions, each of these prior art methods has limitations that render them inadequate for certain applications. For example, bubbling ozone directly into water at ambient pressure has been used as a method to dissolve ozone in aqueous solutions. Such a technique, however, does not optimize the quantity of ozone dissolved, since the ozone bubbles effervesce before a substantial amount of ozone can be dissolved into solution and/or before the ozonated water can be applied to the surface to be treated.
European patent application No. EP 0 430 904 A1 discloses a process for producing ozonated water comprising the step of contacting an ozone-containing gas with fine droplets of water. However, this process is less than optimal since it provides limited contact between the ozone-containing gas and water. Additionally, this application does not teach a method of keeping the ozone in solution until it is delivered to a point of use. Thus, it is possible that, upon delivery, a large quantity of the ozone dissolved in solution will effervesce, and the benefits of the mixing process will be lost.
Several methods utilizing cooling to increase the quantity of dissolved ozone in aqueous solutions have also been proposed. For example, U.S. Pat. No. 5,186,841 discloses a method of ozonating water comprising injecting ozone through an aqueous stream across a pressure drop of at least 35 psi. The ozonated stream is then combined with a second stream that is preferably a portion of an aqueous solution that is recirculating in a cooling water system. The resultant stream is forced to flow at a velocity of 7 feet per second for a distance sufficient to allow 70% of the ozone to be absorbed. Additionally, U.S. Pat. No. 4,172,786 discloses a process for increasing the quantity of dissolved ozone in an aqueous solution by injecting an ozone containing gas into a side stream conduit that circulates a portion of cooling water. U.S. Pat. No. 5,464,480 discloses a process for removing organic materials from semiconductor wafers using ozonated water. Specifically, this patent teaches that high ozone concentration water, suitable for use in the disclosed process may be obtained by mixing ozone and water at a temperature of from about 1° C. to 15° C.
The use of pressurized vessels and distribution systems is also a known method of improving the level of dissolved ozone. A system disclosed in U.S. Pat No. 5,971,368 describes a system where by introducing a gas into a pressurized vessel containing a liquid; delivering the resulting admixture to a point of use through a pressur
Archer Shivaun
Blankenburg Charles
Drabek Steven
Giletto Anthony
Hitchems G. Duncan
Lynntech Inc.
Ogden Necholus
Street & Steele
Streets Jeffrey L.
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