GB2248452A - Aqueous detergent compositions containing protease - Google Patents

Abstract

There is provided an aqueous liquid detergent composition comprising a surfactant concentrate and a proteolytic enzyme originating from a micro-organism, characterized in that the composition further comprises calcium and EDTA (or another calcium sequestrant) at a mole ratio of sequestrant to calcium of 1 or less.

Description

ENZYMATIC LIOUID DETERGENT COMPOSITIONS Field of the Invention : The present invention relates to enzymatic liquid detergent compositions. More particularly, it relates to enzymatic liquid detergent compositions which incorporate proteolytic enzyme, and to the stabilisation thereof.

Disclosure of Prior Art: The use of proteolytic enzymes, e.g. serine protease from Bacillus subtilis, in liquid detergent compositions is well known; although these proteolytic enzymes can be of various types and sources, the proteolytic enzymes commonly used are those produced by Bacillus strains. Although satisfactory results as regards performance can be achieved with such proteolytic enzymes, it is frequently necessary to include enzyme-stabilising systems in the liquid detergent compositions to provide a satisfactory enzyme stability during storage of the enzymatic liquid detergent composition.

The prior art includes WO 88/03946 (Novo), which discloses, as detergent additives, combinations of Bacillus proteases with alkaline fungal or actinomycete proteases, e.g. those proteases obtainable from the genera Paecilomyces, Fusarium, and Nocardiopsis. The disclosure extends to the use of the detergent additive as a liquid, with a known enzyme stabiliser such as propylene glycol, for addition to a liquid detergent.

USP 3 707 504 (Procter & Gamble) discloses detergents for laundry and dishwashing, comprising protease from Thermoactinomyces vulgaris ATCC 15734, which are formulated as solid or liquid detergent compositions. This document mentions surprising stability of protease from Thermoactinomyces vulgaris in highly-alkaline detergent systems.

Prior art as to enzyme stabilisation includes the following: JP 47-35192 describes the use of glycerol or sorbitol with borax under certain conditions and proportions, to stabilise enzyme preparations including liquid washing materials.

DE 27 28 211 (Unilever) describes the use of polyols of 2 to 6 hydroxy groups together with boric acid or borate in ratios less than 1, particularly in unbuilt detergents.

GB 2 079 305 (Unilever) describes the use of polyols together with boric acid and/or borate and polyacrylate polymers as stabilising agents, while EP 0 080 223 (Unilever) describes the combined use of boric acid or borate and polyol or polyamino compounds with reducing salts, and EP 0 126 505 (Unilever) describes the use of boric acid or borate and reducing salts, together with succinic or other dicarboxylic acids.

Other prior art, e.g. EP 0 028 865 and 0 028 866 (Procter & Gamble), and USP 4 111 855 (Procter & Gamble), discloses use of further stabilisers, such as calcium with short-chain aliphatic acids such as formate or acetate, and ethanol.

EP 0 317 307 (Unilever) describes the use of enzymes of the Proteinase K type as of particular value as proteolytic enzymes showing good stability in both aqueous and non-aqueous enzymatic liquid detergent compositions.

EP 0 344 828 (Unilever) describes isotropic aqueous liquid detergent compositions which can contain protease enzymes and also contain soaps and diols.

Prior art as to EDTA and similar materials in detergent or cleaning compositions includes the following: EP 0 093 784 (Thilo) describes enzymatic cleaning materials for contact lenses, in the form of effervescent tablets containing trypsin, amylase, lipase, citric acid, sodium bicarbonate, calcium acetate and EDTA, within broad ranges.

JP 63-101493 (Lion Corp.) describes detergent compositions containing a) bacterial protease enzyme, b) a chelating builder, with chelation constant > =6, c) calcium, with a b:c mole ratio of 0.9 or greater. An example gives EDTA as the chelating agent.

Other prior specifications mentioning the use of organic sequestrants such as EDTA in detergent or cleaning products include: GB 1 572 605 (Procter & Gamble), US 4 169 817 (Weber, assr to Midwest Biochemical), US 4 243 543 (Economics Laboratory), US 4 711 739 (S.C.Johnson), US 4 609 493 (Alcon), DE 1 942 849 (Kortman & Schulte), DE 20 62 465 (Henkel), WO 85/03247 (Eye Products), EP 0 342 177 (Procter & Gamble), EP 0 141 607 (Bausch & Lomb), EP 0 086 511 (Procter & Gamble), EP 0 204 342 (Lion Corp), EP 0 118 933 (Procter & Gamble), and JP 01-146998 (Matsushita).

Background. Aims and Summary of the Present Invention: The prior art mentioned above includes a variety of enzymestabilising systems for use in connection with liquid detergent compositions, and these systems can indeed be effective.

However, the ingredients for them can be unacceptably expensive, and it is desirable to find a way to reduce or avoid their use. Furthermore, the degree of stabilisation achieved by such compositions can be less than desired, especially for detergent liquids that may require to be stored at relatively high ambient temperatures, and it is desirable to provide compositions having further improved stability and/or adequate stability for storage at high ambient temperature.

According to the invention there is provided an aqueous liquid detergent composition comprising a surfactant concentrate and a proteolytic enzyme derived from a microorganism, characterised in that the composition further comprises calcium and EDTA or other organic calcium sequestrant, e.g.

NTA, DTPA, or a sequestrant of the Dequest (TM) series. These additives can be used at a mole ratio of EDTA or other sequestrant to Ca of, for example, 1 or less, e.g. less than 0.9, e.g. in the range of about 0.2 to about 0.9, e.g. about 0.4, and in stabilising amounts such as, for example, a concentration range of 0.1-5t EDTA or other sequestrant, e.g.

up to about 1% or 2% EDTA, e.g. about 0.5% EDTA, or other sequestrant.

In practice, the formulation quantities are often adjusted empirically to prevent unwanted side-effects such as, for example, precipitation and the clouding of surfactant ingredients in the compositions (e.g. by lowering the total ionic content, including that of sequestrant, or adding hydrotrope such as alcohol).

Examples of these liquid formulations have been found to show uncommonly good storage stability and prolonged shelf-life at relatively high, even tropical, ambient temperatures of, for example, about 450C.

The compositions of this invention can be formulated either as formulations of improved stability, or as formulations which achieve economy in the use of various stabilisers in order to achieve adequate storage stability. For example, some of the formulations need less than normal amounts of known enzyme stabilisers, and/or which can be formulated without such stabilisers, for useful storage stability.

Further and Detailed DescriPtion of the Invention: The protease enzymes can preferably be included according to the present invention in an amount of 1 to 100 GU/mg liquid detergent, e.g. from 2 to 50 and usually from about 5 to 20 GU/mg. A GU is a Glycine Unit, which is defined as the proteolytic enzyme activity which, under standard conditions, during a 15-minute incubation at 40"C, with N-acetyl casein as substrate, produces an amount of NH2-group equivalent to 1 micromole of glycine. Preferably, the amount ranges from 2 to 50 and particularly preferably from 5 to 20 GU/mg.

In other units, protease can, for example, be used in an amount ranging from about the order of 0.0002 to about the order of 0.05 Anson units per gram of the detergent composition.

Preferred examples of a protease enzyme to be used in the present compositions are the subtilisin varieties sold as Alcalase and Savinase (Trade Marks of Novo-Nordisk A/S) or Maxacal (TM of Gist-Brocades/IBIS) or as Opticlean (ex MKC) or API22 (ex Showa Denko), which has pI approximately 10. Other useful examples of protease include Maxatase, Esperase (Trade Marks), proteinase K and subtilisin BPN'.

Enzymes other than protease can also be present, for example lipase and/or amylase and/or cellulase.

The liquid detergent compositions in which the proteinase is incorporated according to the present invention can be isotropic aqueous built or unbuilt liquid detergents which on their own are well known in the art. Many aspects of formulation applicable to such compositions, including suitable types and levels of most of the basic ingredients and optional additives, are described in the following patent specifications, hereby incorporated by reference: EP 0 126 505 (Unilever) and EP 0 225 654.

The detergent-active compounds in the compositions can, for example, be chosen from among known anionic and/or nonionic surfactants, optionally cationic and/or nonionic surfactants, or zwitterionic or amphoteric surfactants, e.g. those descri bed in, for example, the textbook 'Surface-Active Agents and Detergents', I and II (Schwarz, Perry, & Berch).

Of particular interest and suitability are known nonionic detergents including alkoxylated alcohols, e.g. c8-18 alkoxylates of average 2-20 alkoxylate residues per mole, usually, for example, ethylene or propylene oxide residues, e.g. C13-15 alcohol containing average about 7 ethoxylate groups per mole.

Also suitable are, for example, condensates of alkylphenols (C6-22) with 5-25 alkylene oxide groups per mole, e.g. 5-25 EO; mixed ethoxylated and subsequently propoxylated alcohols; long-chain tertiary amine oxides, etc.

Cationic detergents of particular interest and suitability include, for example, di(Cg-18) alkyl dimethyl ammonium halides, e.g. di-tallow alkyl dimethyl ammonium chloride, or di(hardened tallow alkyl) dimethyl ammonium halides and are usually used in relatively minor amount in the detergent formulations of the present invention.

The pH of the liquid detergent compositions can be chosen at will from a wide range, e.g. from about pH 7 to about pH 12, preferably a milder alkaline range from about pH 7 to about pH 9.5, alternatively a stronger alkaline range from about pH 9 to about pH 11 or more.

Also included within the scope of the invention are liquid detergent compositions incorporating the defined protease as well as an enzyme stabiliser such as glycerol-borate stabiliser, possibly in a lower amount than those amounts hitherto proposed.

Useful stabilisers include, for example, boric acid, boric oxide, borax or sodium ortho-, meta-, or pyroborate, generally at about 0.25-15%, e.g. often from 0.5-10%, e.g. from 0.5-3% by weight of'the composition, when calculated as boric acid containing an equivalent amount of boron. Glycerol levels in the compositions can be, for example, about 1-10%, typically about 5%.

The compositions may also comprise other detergent additives, for example without limitation polysaccharides such as pectinates and alginates chosen for compatibility with the pH and pI of the enzyme in use, and polycarboxylates, e.g.

polyacrylates.

Typically, the aqueous liquid detergent compositions comprise from 1-60% by weight of one or more detergent-active compounds, from 0-60% by weight of one or more organic and/or inorganic builders, and optionally other conventional detergent additive ingredients such as soil-suspending agents, hydrotropes, corrosion inhibitors, dyes, perfumes, silicates, optical brighteners, suds- depressants, germicides, anti-tarnishing agents, opacifiers, fabric softening agents, oxygen-liberating bleaches such as hydrogen peroxide, sodium perborate, diperisophthalic anhydride, with or without bleach precursors, buffers and the like. The liquid medium is generally an aqueous medium; it can, for example, be essentially unbuilt (apart from the limited builder effect of the organic sequestrant in amounts as defined above), and can contain water-miscible organic solvent such as methanol or ethanol.Many of the organic calcium sequestrants mentioned in the prior art cited above, and hereby incorporated by reference, are convenient for use in the compositions of the present invention.

The invention is further illustrated by way of non-limitative Example.

EXAMPLE 1 Storage experiments were carried out with a liquid detergent composition of the following formulation % (wiz) Nonionic detergent (Synperonic C13-15 7EO) 20 Cationic detergent (Prapagen S3445) 2 (di-tallow alkyl dimethyl ammonium chloride) Borax (sodium tetraborate 10 aq.) 3 Glycerol 6 Ethanol 5 Calcium chloride 2 aq. 0.5 Tetrasodium EDTA 0.5 Protease (Alcalase 2.5 SOL? 15 GU/mg Minors and Water to 100 In storage tests it has been found that an aqueous detergent composition according to this formulation showed good storage stability with an enzymatic half-life of about 4 to 5 weeks at a storage temperature as high as 450C.

At somewhat lower temperatures, e.g. 370C, it has also been found that the effect of varying calcium and EDTA levels in a formulation otherwise the same as that set out in Example I can be to give substantial improvement of shelf-life and stability from, for example, about 11 weeks without EDTA and calcium together to about 21 weeks in the presence of e.g. 1% calcium chloride and 2.5% EDTA. It has been found that both the calcium and the EDTA together are needed for this effect.

Glycerol is preferred to propylene glycol in formulations similar to that of Example 1. At the higher temperatures e.g.

about 450C, it can sometimes happen that the higher levels of the EDTA additive, e.g. 2% or more, or greater than twice the weight of the calcium chloride additive, can give rise to less preferred inhomogeneity effects in the liquid detergent formulations. Where these occur, they can be adjusted by various known means, e.g. by reducing the ionic strength or adding organic solvent such as ethanol or methanol.

It is apparent that modifications and variations can be applied to the invention and to the several features mentioned and described herein and the documents incorporated by reference, which features can be applied in all combinations and sub-combinations.

Claims (7)

1. An aqueous liquid detergent composition comprising a surfactant concentrate and a proteolytic enzyme derived from a microorganism, characterised in that the composition further comprises calcium and EDTA or other organic calcium sequestrant, e.g. at a mole ratio of sequestrant : Ca of 1 or less, e.g. less than 0.9.

2. A liquid detergent composition according to claim 1, characterised in that the calcium and sequestrant are present in stabilising amounts such as, for example, a concentration of sequestrant in the range of about 0.1-5% EDTA or other sequestrant, e.g. up to about 1% or 2%, e.g. about 0.5% sequestrant.

3. A liquid detergent composition according to claim 1 or 2, characterised in that the surfactant consists essentially of cationic and nonionic surfactant.

4. A detergent composition according to any of claims 1-3, wherein the proteolytic enzyme is present in an amount in the order of about 1 to 100 GU/mg liquid detergent.

5. A detergent composition according to any of claims 1-4, further comprising glycerol borate stabiliser.

6. A detergent composition according to any of claims 1-4, further comprising water-miscible organic solvent such as ethanol.

7. A detergent composition according to any preceding claim, characterised by any one or more of the features described in the foregoing description.