Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Enzyme component of specific activity or source
Reexamination Certificate
2001-06-13
2003-05-27
Kopec, Mark (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Enzyme component of specific activity or source
C510S392000, C510S311000, C510S376000, C510S500000
Reexamination Certificate
active
06569827
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an enzymatic liquid detergent composition with good enzyme-stability. In particular, the present invention concerns a concentrated and physically stable isotropic liquid detergent composition with good protease stability suitable for cleaning textile articles.
BACKGROUND OF THE INVENTION
In general, isotropic compositions are clear liquids wherein all the ingredients are dissolved. Concentrated isotropic liquid detergent compositions are very efficient in use and require less package and transport costs per wash. However, the high concentration of cleaning-effective ingredients is often problematic. One problem is to formulate a composition that is physically stable over a prolonged period of time as the highly concentrated surfactants tend to aggregate and separate out. This causes the composition to become hazy and physically unstable. Moreover, because other ingredients in the composition are also present in high concentrations, these ingredients may also separate out themselves or cause other ingredients to become insoluble.
Yet another problem is to ensure a sufficient storage-stability of the enzyme in concentrated liquid detergent compositions, particularly when protease is used. The prior art has already described various ways in which this problem can be overcome, e.g. by encapsulating the enzymes or by inclusion of enzyme-stabilising systems in such liquid detergent compositions. For example, glycerol/borax is a well-known enzyme stabilising system but, unfortunately, it is rather costly.
WO-A-98/40471 describes a method to improve the storage stability of dissolved laccase, an enzyme that catalyses the oxidation of phenol of which the reaction products can be used for dyeing hair or fabrics. The laccase is dissolved in water and sorbitol. There is no mention of the effect of carbohydrates on protease deactivation and the descriptions does not relate to isotropic liquid detergent compositions for the cleaning of fabrics.
U.S. Pat. No. 5,288,746 relates to liquid laundry detergent composition wherein glucose and glucose oxidase are used for the generation of hydrogen peroxide. To prevent premature hydrogen peroxide generation in the composition Cu2+ or Ag+ ions are incorporated in the composition. Therefore, glucose is not used as enzyme stabilising system but as a substrate for the enzyme.
EP-A-381 262 relates to the stabilisation of lipase in liquid detergent compositions with sorbitol and borax. Sorbitol is relatively expensive and there is a need for more economic alternatives.
U.S. Pat. No. 4,462,922 describes a liquid detergent wherein a mixture of glycerol, boron compound and an antioxidant containing sulphur is used to produce an enzyme-stabilising effect. For this mixture the antioxidant must be present above a certain level, as well as the boric acid or the alkali metal borate. The antioxidant should be present in the mixture in an amount of at least 5% by weight of the final enzymatic aqueous liquid detergent composition, and the boric acid or alkali metal borate in an amount of at least 2% by weight of the final enzymatic aqueous liquid detergent composition. The antioxidant is an alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
However, this prior art composition is less desirable because sulphite salts tend to produce an unpleasant odour. Furthermore, applicants have found that it is problematic to incorporate the enzyme stabilising system of U.S. Pat. No. 4,462,922 in a concentrated isotropic liquid detergent because this leads to a hazy liquid which is no longer isotropic.
Surprisingly, we have now found that one or more of these problems can be overcome by the present invention while maintaining good protease stability.
DEFINITION OF THE INVENTION
Accordingly, the present invention provides a physically stable concentrated isotropic liquid detergent composition comprising
(a) from 10 to 70% of surfactant selected from anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof,
(b) from 0.001 to 10% of protease;
(c) from 2 to 40% of at least one carbohydrate selected from oligosaccharides, polysaccharides and derivatives thereof; and
(d) less than 3% of an antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
Furthermore, the present invention encompasses a method for the stabilisation of protease in a physically stable concentrated isotropic liquid detergent composition comprising the steps of
(I) formulating an said composition comprising
(a) from 10 to 70% of an anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof,
(b) from 0.0001% to 10% of protease; and
(c) less than 3% of an antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates, and
(II) adding 2 to 40% of at least one carbohydrate selected from oligosaccharides, polysaccharides and derivatives thereof, to the composition prepared in step (1).
One of the advantages of the present invention is that it provides a stable isotropic detergent composition that is simple to formulate and offers a significant cost advantage compared to glycerol/borax system.
A further advantage of the inventive composition is that the carbohydrate can be incorporated up to at least 20 wt % without causing physical stability problems.
The inventive composition comprises less than 3 wt %, more preferably less than 2 wt %, most preferably less than 1 wt % of the antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
Isotropic liquid detergent composition are defined for the present purpose as liquid detergent compositions wherein the surfactants do not form liquid crystalline phases, like multi-lamellar droplets of surfactant material. Isotropic liquids are generally not birefringent under static conditions but may be birefringent under flow.
For the purpose of this invention a composition is physically stable when less than 2% phase separation occurs after 2 week storage at 37° C. With isotropic liquids this can be phase separation generally starts with the liquid becoming hazy.
Carbohydrate
The carbohydrate is selected from oligosaccharides and polysaccharides e.g. having up to 30 carbon atoms, and derivatives thereof. The term “oligomer” is usually taken to encompass dimers, trimers and tetramers. Oligosaccharides and their derivatives are especially preferred carbohydrates for use in the present invention, disaccharides, trisaccharides and derivatives thereof, being especially preferred.
One preferred class of preferred carbohydrates comprises the group comprising trisaccharides with a free hemiacetal group. Typical examples of this category are: Cellotriose (&bgr;-D-glucopyranosyl-(1→4)-&bgr;-D-glucopyranosyl-(1→4)-D-glucopyranose. Even more preferred are the trisaccharides without a free hemiacetal group (the so-called non-reducing trisaccharides). Typical example of this category is raffinose (&bgr;-D-Fructofuranosyl &agr;-D-galactopyranosyl-(1→6)-&agr;-(-D-glucopyranoside).
The most preferred carbohydrate comprises the disaccharides of non-mammalian origin. This does not include milk sugar lactose. More specifically the disaccharides with a free hemiacetal group (the so-called reducing disaccharides. Typical examples of this category are: Cellobiose (&bgr;-D-glucopyranosyl-(1→4)-D-glucose) &bgr;-maltose (&agr;-D-glucopyranosyl-(1→4)-&bgr;-D-glucopyranose).
The most preferred disaccharides are compounds without a free hemiacetal group (the so-called non-reducing disaccharides. Typical disaccharides of the last category, are: Sucrose (&bgr;-D-Fructofuranosyl &agr;-D-glucopyranoside) Trehalose (&agr;-D-Glucupyranosyl &agr;-D-glucopyranoside).
The composition herein preferably comprises 5-30%, more preferably 8-25% of at least one carbohydrate.
Add
Olsthoorn Theresia Maria
Ouwendijk Marja
van de Pas Johannes Cornelis
Van Dijk Willem Robert
Elhilo Eisa B
Unilever Home & Personal Care USA , division of Conopco, Inc.
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