Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2002-07-12
2004-02-03
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S234000, C510S302000, C510S367000, C510S372000, C510S375000, C510S378000, C510S426000, C510S436000, C510S477000, C510S480000, C510S536000
Reexamination Certificate
active
06686324
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cleaning solutions and, more particularly, to low-foaming cleaning solutions for removing organic soils from hard surfaces.
BACKGROUND TO THE INVENTION
Low-foaming cleaning solutions useful in removing organic soils, including protein and glyceride-based deposits, are commonly used to clean equipment or utensils in the food processing, dairy, health care, dental and veterinary industries. Equipment used in the food and dairy industries are often cleaned “in-place” by circulating a cleaning solution repeatedly through liquid-carrying pipes of the equipment. In the cleaning of medical, veterinary and dental utensils, items are enclosed in a washing chamber of a washing machine and sprayed with a wash solution which is collected from the washing chamber and recirculated to be sprayed again onto the utensils. This cycle repeats continuously for a predetermined period of time or number of cycles. Foam buildup is objectionable in the above circumstances as it will increase the amount of entrapped air in the recirculating solution. This results in cavitation at the pump or in the recirculating pump losing its prime.
Known low-foaming cleaning solutions include chlorine-based cleaners of high alkalinity, or formulations containing one or more enzymes in a basic solution. Chlorine-based cleaners and enzyme-based cleaners work by breaking large protein, linked amino-acid, glyceride or fatty acid molecules through oxidation and enzymatic action, respectively. The chlorine-based cleaners are based on the high oxidative power of chlorine in combination with an alkaline medium to reduce these large soil particles to smaller units easily dissolved or emulsified by the surface active species present. Similarly, enzymatic cleaners rely on high alkalinity and the chemical breakdown of peptide bonds in proteins for dissolution of soils. In both cases, alkaline conditions result in saponification of fats in the soil, further contributing to the detergency process. Though the actual mechanisms for removing soils differ in both types of cleaning solutions, the effects are similar, namely, large particles are broken down into smaller more water soluble units that are eventually dissolved in the wash liquor.
Drawbacks of chlorine-based cleaners are that their use produces large amounts of waste water containing high amounts of free chlorine. Furthermore, these cleaners are hazardous if mixed with acid solutions (commonly used in two-step cleaning/sanitizing procedures in certain applications) to produce highly poisonous chlorine gas. Also, these cleaners tend to have very pungent odors, may cause skin and eye irritations, and may permanently damage the substrates to which they are applied.
Enzyme-based cleaners, although quite effective in combating protein and lipid-based soils, generally require high temperatures for effective cleaning. Furthermore, the cost of enzyme-based compositions is considerably higher than the cost of most cleaning chemicals. As a consequence, the cost of cleaning with enzymatic-based compositions is generally prohibitive for large-scale applications, and is largely reserved for specialty applications in health, veterinary and dental care.
Hydrogen peroxide based cleaners have become favored more recently because they are odorless, non-corrosive at concentration levels typically employed for cleaning, safe to material substrates, their breakdown products (oxygen and water) are innocuous, and they can be made at low costs. However, the current art does not contemplate a low-foaming, cleaning solution containing hydrogen peroxide which would be useful in the applications discussed herein.
Until now, it has been necessary to add high detergency surfactants to boost the cleaning power of hydrogen peroxide based solutions, in order to achieve the same levels of cleaning efficiency as that of conventional hypochlorite and enzymatic cleaners. Surfactants (or surface active agents) work to decrease the interfacial tension in a solution to facilitate detachment and emulsification of soils. Unfortunately, surfactants which exhibit good detergency will also result in highly foaming solutions, whereas the use of non- or low-foaming surfactants generally leads to poor cleaning compositions. A common solution to this problem is to add silicone-based foam reducing agents to the wash solution. However, these materials tend to allocate and build up in difficult to reach places in the equipment and instruments which facilitates proliferation of microorganisms.
There is therefore a need for a low-foaming cleaning solution which is effective against organic-based soils, exhibits favorable environmental profiles, and possesses a minimal or no risk to the user or to the substrates being cleaned. The present invention is intended to, at least in part, meet these needs.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 3,969,258 to Carandang et al discloses an acidic, low-foaming sanitizing solution designed for use in recirculating systems in the food and milk industries. The solution is based on highly foaming anionic surfactants known for their antimicrobial properties, and foam suppressing agents consisting of a C
8
-C
18
aliphatic alcohol, or a C
9
-C
12
alkyl phenol, in combination with a polyvalent metal compound. The cleaning efficiency of the solution is not discussed and the use of hydrogen peroxide as a cleaning agent is not taught or suggested.
U.S. Pat. No. 4,878,951 to Pochard et al teaches alkaline cleaning formulations which are low foaming and therefore suitable for the cleaning in-place of equipment which circulates food or dairy products. The formulations contain a source of chlorine (e.g. hypochlorite) and a mixture of surfactants, one of which is a high-foaming C
4
-C
8
alkylated diphenyl oxide sulfonate and the other of which is a nonionic surfactant which is stable in the formulation within certain concentration ranges and which acts to suppress foaming. The nonionic surfactant is selected from the group of polyoxyethylene/polyoxypropylene block copolymers and polyalkoxylated linear or branched aliphatic alcohols. The reported solutions are highly alkaline with caustic soda used at the rate of 10% w/w of the total solution composition. This reference does not disclose or suggest the use of alternate non-chlorine based oxidizers, such as hydrogen peroxide.
U.S. Pat. No. 5,855,217 to John describes a device, process and formulation for cleaning heavily soiled surfaces in the food industry. The device mixes a caustic detergent solution and an aqueous solution of hydrogen peroxide to form an unstable,.high foaming cleaning formulation which is ejected, under pressure, towards the surface to be cleaned before the hydrogen peroxide breaks down. The process is based on the generation of a cleaning foam containing hydrogen peroxide in an amount from 0.1% w/w to 1.0% w/w. The formulation taught clearly does not have application to recirculating systems where the presence of foam cannot be tolerated.
WO 93/14183 to the Procter & Gamble Company discloses a detergent composition which is stable and remains colorless over time. This is achieved by adding hydrogen peroxide and a metal sequestering agent to high detergency, high foaming anionic and/or nonionic surfactants. These surfactants do not include low-foaming small chain-alkane sulfonates and alkylarenesulfonates.
Numerous hydrogen-peroxide based cleaning compositions have been proposed, none of which appear suitable for applications involving substrates highly soiled with protein, carbohydrate and lipids, where both high detergency and low or no foaming are required. For example, U.S. Pat. No. 5,602,090 to Melikyan et al describes a hard surface cleaning solution comprising hydrogen peroxide, D-limonene, two anionic surfactants, a non-ionic surfactant, and deionized water. Although the low-foaming sodium 1-octane sulfonate (sold under the commercial name Bioterge PAS-8S) is listed as a possible one of the anionic surfactants, the other surfactant components are high-foaming.
U.S
Ramirez Jose A.
Sullivan Nancy M. A.
Boyer Charles
Clark & Brody
Virox Technologies Inc.
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