Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Enzyme component of specific activity or source
Reexamination Certificate
1999-10-22
2001-02-20
Fries, Kery (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Enzyme component of specific activity or source
C510S530000, C510S226000, C510S320000, C510S321000, C510S319000, C510S382000, C510S383000, C510S337000, C510S339000, C510S498000, C510S500000
Reexamination Certificate
active
06191092
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the enzymatic cleaning of hard surfaces and, more particularly to a liquid stabilized enzyme preparation and to its use for cleaning hard surfaces, above all in dairies/creameries.
Deposits containing proteins and fats are formed on surfaces of containers and pipes which come into contact with milk or milk products in the production and processing of milk. Such deposits, which are extremely difficult to remove, occur to a particularly marked extent in milking machines, milk collection trucks, tanks, pipelines and heaters. On account of the obstinate nature of the soils, equipment of the type in question is generally cleaned with strongly alkaline and, in some cases, also strongly acidic cleaners which have to handled with great care on account of their highly corrosive properties. In addition, where cleaners of this type are used on sensitive materials, they can be expected to cause corrosion unless special precautionary measures are taken. Before they discharged into the main drainage system, the cleaners have to be neutralized.
On account of the difficulties involved in using highly alkaline or strongly acidic cleaning solutions, there has been no shortage of attempts to develop cleaning solutions which clean as effectively as the strongly alkaline or highly acidic cleaners despite a substantially neutral pH value. Above all, it has been proposed to use enzymes, especially proteases, for this purpose. Numerous publications on this subject have appeared in the literature (cf. for example International patent application WO 96/6910 where more literature references can be found). Although in principle adequate cleaning is possible, even at a neutral pH, where proteases are used, the use of these enzymes is attended by other difficulties. Thus, liquid concentrates are preferably used for preparing the actual cleaning solution, especially in institutional cleaning. Unfortunately, liquid enzyme concentrates quickly lose their effectiveness in storage because the enzymes present are denatured or otherwise lose their activity. For this reason, numerous attempts have been made to improve the stability of liquid enzyme preparations in storage by the addition of so-called stabilizers. For example, the addition of boric acid or borates and soluble potassium salts and even the addition of polyhydric alcohols are widely practised. Unfortunately, these stabilizers still do not provide a totally satisfactory solution to the problem.
The problem addressed by the present invention also was to improve the stability of liquid enzyme preparations. Another problem addressed by the invention was to develop enzyme preparations which would be suitable for cleaning hard surfaces, especially in the dairy industry. In addition, these enzyme preparations would be suitable for the preparation of reusable cleaning solutions, above all of the type required for institutional cleaning.
It has surprisingly been found that the problems stated above can be solved by the addition of certain basic nitrogen compounds to the liquid enzyme preparations.
DESCRIPTION OF THE INVENTION
Accordingly, the present invention relates to a liquid stabilized enzyme preparation which contains a protease, a solvent from the group consisting of ethylene glycol, propylene glycol, glycerol and mixtures thereof and a stabilizer from the group consisting of polyhexamethylene biguanide, N,N-bis-(3-aminopropyl)-dodecyl amine, salts thereof and mixtures of these compounds. In a preferred embodiment, the enzyme preparation additionally contains water and optionally other auxiliaries, more especially from the group of surfactants, solubilizers and mixtures thereof. The present invention also relates to the use of the enzyme preparation for the preparation of a cleaning solution for cleaning dairy equipment and to a process for cleaning dairy equipment using such cleaning solutions in the substantially neutral to weakly alkaline range.
The basic nitrogen compounds used to stabilize the liquid enzyme preparation are substances which, hitherto, have been used almost exclusively in disinfectants by virtue of their antimicrobial activity. Thus, polyhexamethylene biguanide hydrochloride is available for this purpose under the names of Lonzabac BFG and Vantocil IB from Lonza and Zeneca Biocides, respectively. N,N-bis-(3-aminopropyl)-dodecyl amine is available for this purpose under the name of Lonzabac-12.30 or Bardac 21from Lonza AG. The fact that these antimicrobial agents have a stabilizing effect on liquid enzyme preparations was not known. One particular advantage is that even very small quantities of these basic nitrogen compounds are sufficient to stabilize the liquid enzyme preparation. They are preferably used in quantities of about 0.5 to about 5% by weight and more preferably in quantities of about 1 to about 3% by weight, based on the liquid enzyme preparation as a whole, although it may even be appropriate in special cases to use the stabilizers in quantities outside these concentration ranges. The above-mentioned commercial forms of the two stabilizers, i.e. as the hydrochloride or free base, are the forms in which they are preferably used although it is of course also possible to use other salts of the basic nitrogen compounds should this appear appropriate in any particular case. Apart from the basic nitrogen compounds themselves, any salts with inorganic or organic acids which are soluble in the enzyme preparation may also be used.
The liquid enzyme preparations contain as solvent at least one substance from the group consisting of ethylene glycol, propylene glycol and glycerol. These solvents may be used on their own although they are preferably used together with water as an additional solvent. The content of solvents from the group consisting of ethylene glycol, propylene glycol, glycerol and mixtures thereof in the enzyme preparations is preferably from about 10 to about 70% by weight and more preferably from about 30 to about 50% weight, based on the preparation as a whole. If water is used as an additional solvent, its content is preferably from about 5 to about 40% by weight and more preferably from about 10 to about 30% by weight, again based on the liquid enzyme preparation as a whole. Since potassium salts generally have a stabilizing effect on enzyme solutions, tap water is preferably used for the enzyme preparations.
Although the stabilizing effect of the nitrogen-containing bases mentioned above extends to liquid preparations of any enzymes, it is preferably used in accordance with the invention for stabilizing solutions of cleaning-active enzymes, i.e. for enzymes which are of use in some way or other in the cleaning of hard surfaces or textiles. Accordingly, the enzyme preparations stabilized in accordance with the invention preferably contain at least one enzyme from the group of proteases (peptidases), amylases, cellulases, glycosidases, lipases and oxidoreductases. The preparations according to the invention may also contain several enzymes from various classes providing no troublesome interactions between the enzymes occur. For the particularly preferred application of the preparations according to the invention, i.e. the cleaning of hard surfaces in the processing of milk, the preparations contain at least one protease, more particularly a protease on its own or in the form of a mixture with other proteases.
The quantity of enzyme in the preparations according to the invention is selected according to the purpose for which the preparations are intended. Accordingly, the quantity of enzymes can be freely selected within very wide limits. The advantageous stabilizing effect of the basic nitrogen compounds occurs at all enzyme concentrations. The enzyme concentration in the preparations is of course also dependent upon the specific activity of the particular enzyme used. Accordingly, where quantities are mentioned in the following for the enzymes, they should be regarded only as rough guides which may be exceeded in either direction as required. The
Bragulla Siegfried
Potthoff Andreas
Serve Wilfried
Fries Kery
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Murphy Glenn E. J.
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