Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Enzyme component of specific activity or source
Reexamination Certificate
2001-02-01
2003-10-28
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Enzyme component of specific activity or source
C510S108000, C510S111000, C510S113000, C510S161000, C510S224000, C134S001000, C134S002000, C134S022140, C134S022160, C134S022170, C134S022190, C134S025100, C134S025300, C134S035000
Reexamination Certificate
active
06638902
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solid enzyme cleaning composition in which the enzyme is stable in the presence of mixtures of carbonate and bicarbonate at alkaline pH, and methods employing this composition. The enzyme cleaning composition preferably employs weight ratios of carbonate and bicarbonate to stabilize one or more enzymes in a solid, a concentrate, and/or a use composition, and at temperatures higher than ambient.
BACKGROUND OF THE INVENTION
A major challenge of detergent development for the health care industry, restaurants, and homes is the successful removal of soils that are resistant to conventional treatment and the elimination of chemicals that are not compatible with the surroundings. One such soil is protein, and one such chemical is chlorine or chlorine yielding compounds, which can be incorporated into detergent compounds or added separately to cleaning programs for protein removal. Protein soil residues, often called protein films, occur in health care, in use and maintenance of medical instruments and devices, in food processing, in restaurants, in laundries, and in home cleaning situations.
In the past, chlorine has been employed to degrade protein by oxidative cleavage and hydrolysis of the peptide bond, which breaks apart large protein molecules into smaller peptide chains. The conformational structure of the protein disintegrates, dramatically lowering the binding energies, and effecting desorption from the surface, followed by solubilization or suspension into the cleaning solution. The use of chlorinated detergent is not without problems, such as harshness and corrosion. In addition, a new issue may force change upon both the industry, consumers, and detergent manufacturers: the growing public concern over the health and environmental impacts of chlorine and organochlorines.
Detersive enzymes represent an alternative to chlorine and organochlorines. Enzymes have been employed in cleaning compositions since early in the 20
th
century. However, it took years of research, until the mid 1960's, before enzymes like bacterial alkaline proteases were commercially available and which had all of the pH stability and soil reactivity for detergent applications. Patents issued through the 1960s related to use of enzymes for consumer laundry pre-soak or wash cycle detergent compositions and consumer automatic dishwashing detergents. Early enzyme cleaning products evolved from simple powders containing alkaline protease to more complex granular compositions containing multiple enzymes to liquid compositions containing enzymes.
Solid cleaning compositions containing enzymes have advantages compared to liquid forms. In liquid compositions, various factors can cause enzyme degradation. For example, enzymes often denature or degrade in an aqueous medium resulting in the serious reduction or complete loss of enzyme activity. For these reasons and for expanded applications, it became desirable to have solid enzyme compositions.
The use of solid block detergents in institutional and industrial cleaning operations was pioneered using highly alkaline material, based on a substantial proportion of sodium hydroxide. Initial solid block products (and predecessor powder products) used a substantial proportion of a solidifying agent, sodium hydroxide hydrate, to solidify the cast material in a freezing process using the low melting point of sodium hydroxide monohydrate (about 50° C.-65° C.). The active components of the detergent were mixed with the molten sodium hydroxide and cooled to solidify. The resulting solid was a matrix of hydrated solid sodium hydroxide with the detergent ingredients dissolved or suspended in the hydrated matrix. Heating an enzyme in molten sodium hydroxide would most often inactivate the enzyme.
In these early products sodium hydroxide was an ideal candidate because of the highly alkaline nature of the caustic material provided excellent cleaning. In recent years, attention has been directed to producing a highly effective detergent material from less caustic materials such as soda ash, also known as sodium carbonate, because of manufacturing, processing, etc. advantages. Sodium carbonate is a milder base, thus it is substantially less strong (has a smaller K
b
) than sodium hydroxide. This disadvantage has been addressed. Initially, solid detergents were made of substantially hydrated carbonate, which contained at least about seven moles of water of hydration per mole of sodium carbonate and were not dimensionally stable. This disadvantage has also been addressed. One disadvantage has not been addressed, stably including an enzyme in a carbonate based solid cleaner.
A marketable solid enzyme composition must include an enzyme that is stabilized so that it will retain its functional activity for prolonged periods of (shelf-life or storage) time. The enzyme must also remain stable for a sufficient time in use to provide adequate cleaning. If a stabilized enzyme system is not employed, an excess of enzyme is generally required to compensate for expected loss. However, enzymes are expensive and are in fact the most costly ingredients in a commercial cleaning composition, even though they are present in relatively minor amounts. There remains a need for methods and compositions for stabilizing enzymes in cleaning compositions, particularly in carbonate-based solids at alkaline pH.
SUMMARY OF THE INVENTION
The present invention relates to a solid enzyme cleaning composition in which the enzyme is stable in the presence of mixtures of carbonate and bicarbonate at alkaline pH, and methods employing this composition. The enzyme cleaning composition preferably employs weight ratios of carbonate and bicarbonate to stabilize one or more enzymes in a solid, a concentrate, and/or a use composition, and at temperatures higher than ambient. The present composition maintains stability of the enzyme at alkaline pH, which preferably falls in the range of about 8 to about 11.5. The present composition preferably includes a mixture of carbonate and bicarbonate in which the weight ratio of carbonate to bicarbonate is in the range of about 0.5:1 to about 4.75:1.
In an embodiment, the solid enzyme cleaning composition includes a detersive enzyme; a mixture of carbonate and bicarbonate; and one or more of a binder including a defined carbonate hydrate, a surfactant, a builder, a chelating agent, or a combination thereof. These ingredients are preferably formulated so that the detersive enzyme retains at least about 50% of its initial activity at 120° F. for at least about 30 minutes after forming a use composition. In an embodiment, the solid enzyme cleaning composition includes a surfactant, a detersive enzyme, a mixture of carbonate and bicarbonate, a binder including a defined carbonate hydrate, a builder, and a chelating agent. The composition can also include one or more dyes or fragrances.
The present composition can stabilize one or more of a variety of enzymes, particularly any of a variety of detersive enzymes. Detersive enzymes that can be employed in the present compositions include a protease, an amylase, a lipase, a cellulase, a peroxidase, a gluconase, or a mixture thereof. Preferably the detersive enzyme is a protease, an amylase, a lipase, a cellulase, or a mixture thereof. Preferred proteases include an alkaline protease, such as an alkaline protease derived from
Bacillus alcalophilus
. Preferred amylases include an endoamylase. Preferred lipases include a lipolase.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
As used herein, bicarbonate, carbonate, carbonic acid salt, and the like are used to refer to a salt such as sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate or another salt obtained by or that can be visualized as being obtained by full or partial neutralization of carbonic acid. The weight percent of a salt of carbonate or bicarbonate can be expressed either as the weight percent of just the anionic carbonate or bicarbonate, or of the entire salt including the cation.
As used
Bradley Tareasa Lynn
Chandler Denise
Rabon Reid
Swart Sally K.
Tarara James J.
Ecolab Inc.
Elhilo Eisa
Gupta Yogendra N.
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