NO773724L - ENZYMATIC LIQUID DETERGENT. - Google Patents

Description

Enzymatic liquid detergent.

The invention relates to an enzymatic liquid product

and more particularly an enzymatic detergent composition with improved storage stability.

Liquid detergent mixtures are well known in the art, and following the revival of interest in enzymes for incorporation into detergent mixtures, several proposals have been made regarding enzymatic liquid detergent mixtures.

Despite these proposals, such enzymatic liquid detergent mixtures have not been brought to the market to any particular extent, primarily because serious instability problems occur when enzymes are incorporated into liquid detergent mixtures. This problem is well known in the field, and it is e.g. have been proposed to reduce the instability of enzymes in liquid detergent mixtures by incorporating stabilization systems into such products.

Thus, it is e.g. in Japanese patent application no. 47/35192, laid out on 24 November 1972, proposed to produce liquid, stable enzyme preparations, including enzymatic liquid detergent mixtures, by mixing in such a combination of polyalcohols and borax. According to the aforementioned Japanese application, these polyalcohols, exemplified by sorbitol and glycerol, are used in an amount of at least 5% by weight of the final mixture, preferably 10-30% by weight. The borax is used in an amount of at least 20%, preferably 50-100% by weight of the polyalcohol. The weight ratio of polyalcohol to borax in the mixture should therefore be equal to or above 1."

The products according to this previous proposal also have, which has been experimentally determined by a repetition of example I, a pH value in the range 3.9-7.4.

It has now been found that the storage stability of enzymatic liquid detergent compositions with a pH value above 7.5, preferably between 8.5 and 11.0 (at 25<0>c'! can be significantly improved by incorporating a stabilization system comprising one or more polyhydroxy compounds, to be defined more specifically in the following, and boric acid or a boron equivalent thereof, the weight ratio between the polyhydroxy compounds and the boric acid or equivalent thereof being less than 1 (calculated on the basis of borax). In comparison with combinations according to the above-mentioned Japanese patent application, the systems according to the present invention show a significantly improved enzyme stabilizing effect.

The polyhydroxy compounds to be used in connection with the invention contain only C, H and O atoms. They are free of other (functional) substituting atoms such as N-, S-

and the like. The polyhydroxy compounds should contain at least two hydroxy groups, and may even contain up to 6 hydroxy groups. Typical examples of polyhydroxy compounds which are particularly well suited for use in connection with the invention are such diols as 1,2-propanediol, ethylene glycol, erythritol, polyols, e.g. glycerol, sorbitol and mannitol.

Generally, the polyhydroxy compound is present in an amount of at least 4% by weight of the final composition, up to 25% by weight. The amount preferably ranges from 5 to 15% by weight of the final mixture

The boric acid or boron equivalent thereof, e.g. boron oxide, borax and other alkali metal borates which are capable of reacting with a polyhydroxy compound, e.g. sodium, ortho-, meta- and pyroborates, are used in such an amount that the weight ratio between the polyhydroxy compound and the boron compound is less than 1 (calculated on the basis of borax). This means that the boron compound is used in an amount of more than 100% of the amount of the polyhydroxy compound. In general, the amount varies from y 100 to 200% by weight, and preferably y 100 to 160% by weight of the polyhydroxy compound.

The weight ratio between polyhydroxy compound and boric acid or equivalent is less than 1, generally from 0.5 up to just under 1.

The enzymatic liquid mixtures into which the stabilization systems according to the invention are mixed can be aqueous liquid systems, e.g. simple solutions, but they are preferably aqueous liquid detergent mixtures whose essential ingredients include enzymes, active detergents and water, with the pH value being above 7.5, preferably between 8.5 and 11.0, or

adjusted to this area by suitable means.

The enzymes to be mixed in can be proteolytic, amylolytic and cellulolytic enzymes as well as mixtures of these. They may be of any origin, for example, of vegetable, animal, bacterial, fungal and yeast origin. However, their selection is governed by various factors such as pH activity and/or stability optima, thermostability, stability to active detergents, builders and so on. In this regard, bacterial or fungal enzymes are preferred, e.g. bacterial amylases and proteases, as well as fungal cellulases.

The present invention is of particular use for enzymatic liquid detergents which comprise bacterial proteases whose pH-optimum lies in the range between 8.0 and 11.0, but it should be understood that enzymes with a slightly lower or higher pH-optimum can still be used in the products according to the invention, taking advantage of this.

Suitable examples of proteases are the subtilisins obtained from particular strains of B. subtilis and.B. licheniformis, e.g. the commercially available subtilisins "Maxatase" from Gist-Brocades' N.V. , Delft, The Netherlands) and "Alcalase" from Novo Industri A/S, Copenhagen, Denmark). .As indicated above., the present invention is of. particular benefit for enzymatic liquid detergents comprising enzymes with pH activity and/or stability optima above 8.0, e.g. enzymes which are usually also called high-alkaline enzymes.

Particularly suitable is a protease, obtained from a strain of Bacillus, which has maximum activity through the pH range 8-12, developed and sold by Novo Industri A/S under the trade name "Esperase". The production of this enzyme and analogous enzymes is described in British Patent No. 1 243 784 (Novo).

Highly alkaline amylases and cellulases can also be used, e.g. α-amylases obtained from a particular strain of B. licheniformis, described in more detail in British Patent No. 1,296,839 (Novo).

The amount of enzymes present in the liquid mixture may vary from 0.001 to 10% by weight, and preferably from 0.01 to. 5% by weight.

, The liquid detergent mixtures according to the invention further comprise as an essential ingredient an active detergent material, which can be an alkali metal or alkanolamine soap of a Clo-c24 fatty acid, including polymerized fatty acids

or an anionic, nonionic, cationic, zwitterionic or amphoteric synthetic detergent material, or mixtures of any of these.

Examples of anionic synthetic detergents are salts (including sodium, potassium, ammonium and substituted ammonium salts, e.g. mono-, di- and triethanolamine salts) of<Cg>-<C>2o-alkylbenzene sulfonates, Cg-C ^-primary or secondary alkanesulfonates, C8-C24-olefin sulfonates, sulfonated polycarboxylic acids, prepared by sulfonation of the pyrolyzed product of alkaline earth metal citrates, e.g. as described in British Patent No. 1082 179, C8-C22-alkyl sulfates, C8-C4-alkyl polyglycol ether sulfates (containing up to 10 moles of ethylene oxides); additional examples are described in "Surface Active Agents and Detergents" (Volumes I and II) by Schwartz, Perry and Berch.

Examples of non-ionic synthetic detergents are the condensation products of ethylene oxide, propylene oxide and/or butylene oxide with C0-Cn0-alkylphenols, CQ-C,Q-primary or sec.-aliphatic alcohols, Cg-C- ^.g-f one acid amides; further examples of nonionic substances include tertiary amine oxides with one C 8 -C 8 -alkyl chain and two C 1 -C 2 -alkyl chains. The above reference also describes further examples of non-ionic substances.

The average number of moles of ethylene oxide and/or propylene oxide present in the above non-ionic substances varies from 1 to 30; mixtures of different non-ionic substances, including mixtures of non-ionic substances with a lower and a higher degree of alkylation, can also be used.

Examples of cationic detergents are the quaternary ammonium compounds, e.g. alkyldimethylammonium halides, but such cationic substances are less preferred for incorporation into enzymatic detergent compositions.

Examples of amphoteric or zwitterionic detergents are N-alkyl amino acids, sulfobetaines, condensation products of fatty acids and protein hydrolysates, but due to their relatively high price they are usually used in combination with an anionic or non-ionic detergent. Mixtures of the different types of active detergents can are also used, and preference is given to mixtures of an anionic and a non-ionic detergent active substance. Soaps (in the form of their sodium, potassium and substituted ammonium salts, e.g. triethanolamine salts) of C 20 -C 24 fatty acids, as well as depolymerized fatty acids, can also be used, preferably

in connection with a . anionic and/or a nonionic synthetic detergent, and can exert a beneficial influence on the foaming behavior of the final product.

The amount of active detergent material varies

from 10 to 60%; if mixtures of. e.g. anionic and non-

ionic material is used, the relative weight ratio varies from 1:1 to 1:10. If a soap is also mixed in, the amount thereof is from 1 to 40% by weight.

Although the liquids may contain up to 40% of a suitable builder, e.g. sodium, potassium and ammonium or substituted ammonium pyro- and -tripolyphosphates, -nitrile triacetates, -ether polycarboxylates, -eitrates, -carbonates, -orthophosphates, polyelectrolytes, e.g. polyvinyl methyl ether/maleic anhydride copolymers and so on, the present invention is of particular use for use in unstructured liquid detergents.

The amount of water present in the detergent mixtures

according to the invention, varies from 5 to 70% by weight.

André conventional materials may also be present

in the liquid detergent mixtures according to the invention, e.g. dirt carriers, hydrotropes,1 corrosion inhibitors, dyes, perfumes, silicates, optical brighteners, foam boosters, defoamers, germicides, anti-stain agents, opacifiers, fabric softeners, oxygen-releasing bleaches, e.g. sodium perborate or -per-'carbonate with or without bleach precursors, buffers and the like.

The pH value of the final product is higher than 7.5 and should preferably lie in the range from 8.5 to 11.0, and is, if necessary, buffered to a value in the aforementioned range by adding a suitable buffer system (e.g. with dimethylglycine).

In the following, the invention will be illustrated with help

of examples. In the examples, the percentages indicate weight. In the examples, the length of the half-life of the enzyme was determined as follows: A continuously taken sample from a solution to be sealed was continuously diluted (1:200) and continuously examined for enzymatic activity (for proteolytic activity, casein was used as substrate). The logarithms of the remaining activity were plotted against time, and the first-order rate constant K-^ was calculated.

The enzyme's factor Ft for the half-life length is defined

■ as: 2 time, at which the enzymatic activity y is half of the original enzymatic activity.

EXAMPLE I

In this example, aqueous systems containing a bacterial protease, "Alcalase" from Novo, were tested. These aqueous systems contained per liter:

6.2 molar pentasodium tripolyphosphate

0.12 molar dimethylglycine

1.7 g "Alcala.se" (activity 10.6 AU/g) .

The pH of the solution was 10, and the temperature '57°C... The rates of loss of activity of the enzyme were measured in this system with and without the stabilization systems indicated below and the enzyme's half-life extension factor was determined. The following results were obtained:

These results show the increased Ft~ values obtained with the stabilization systems according to the invention. Tests no. 8 and 11 are not according to the invention, (—p ratio > 1) and show that with these conditions reduced F, values are achieved ,

in comparison with — ratio > 1. Tests hr. 7-9 and 10-12 show that a decreasing ratio gives better F, values, in contrast

B t

to what is known from the state of the art which prescribes —B-for-hold to be ^ .1. With only 2%, 4%, 8% and 9.45% borax (no addition of polyhydroxy compound), the following Ft values were obtained: 1.0, 1.3, 1.8 and 2.4.

EXAMPLE II..

In this series of experiments, a bacterial protease, "Esperase" from Novo (activity 41.5 KNPU/g) was used. The aqueous system was identical to that of Example I, but the temperature was now 60°C. With 4%. erythritol and 7.4% borax (-| = 0.54) an F^ of 2.5 was obtained.

EXAMPLE III

in a manner analogous to that of Example I, systems with a bacterial α-amylase ("Thermamyl") were tested. The aqueous system contained per liters:

0.12 m pentasodium tripolyphosphate

0.1 m glycine

0.5 g "Thermamyl" (activity 450 KNU/g).

The pH value was 9.95 and the temperature 59.3°C. With a stabilizing system containing 6% ethylene glycol + 9.2% borax B ratio = 0.65), an F t value of 2.2 was achieved.

EXAMPLE IV

Example I was repeated with a stabilizer system containing 10% glycerol and varying amounts of borax. The following results were obtained:

Claims (8)

1. Aqueous enzymatic liquid detergent mixture with: improved storage stability, characterized in that it includes a stabilization system that includes: a) 4-25% by weight, calculated on the final product, of one or more polyhydroxy compounds which contain only C, H and O atoms, and which contain 2-6 hydroxy groups} b) boric acid or a boron equivalent thereof, which is i capable of reacting with the polyhydroxy compound, the weight ratio a:b being less than 1, and the mixture having a pH value of 7.5-11.0.. 2.. Detergent mixture as specified in claim 1, characterized in that the weight ratio a: b varies from 0.5 to just below 1. 3. Mixture as stated in claim 1 or 2, characterized in that the polyhydroxy compound is 1,2-propanediol, ethylene glycol, erythritol, glycerol, sorbitol or mannitol or a mixture thereof.... 4. Mixture as specified in claim 1 or 2, characterized in that the boron equivalent of boric acid is boron oxide, borax or an alkali metal ortho-, meta- or pyroborate. 5. Mixture as stated in claims 1 to 4, characterized in that the polyhydroxy compound is present in an amount of 5-15% by weight, calculated on the final mixture. 6. Mixture as stated in claims 1 to 5, characterized in that it has a pH value of 8.5-11.0. 7. Mixture as stated in claims 1 to 6, characterized in that it comprises from 0.001 to 10% by weight, calculated on the final mixture, of proteolytic, amyolytic or cellulolytic enzymes or mixtures thereof, from 10 to 60% by weight of a detergent-active material , and from 5 to 70% by weight of water. 8. Mixture as specified in claims 1 to 7. characterized in that it comprises a bacterial proteolytic enzyme which has a pH optimum between 8 and 12.