Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Reexamination Certificate
1998-12-28
2002-09-03
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
Reexamination Certificate
active
06444023
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to liquid laundry starch concentrates, more particularly for use in institutional laundries, which contain an aqueous suspension of starch and a certain preservative system and to the use of the preservative system in liquid starch concentrates.
Starch-containing preparations are generally used for starching or finishing laundry. They are used either as a “boil-up” of initially non-gelatinized starch or as solution of pregelatinized starch or as a suspension of non-gelatinized starch which only gelatinizes on the laundry on exposure to relatively high temperatures, for example during ironing or mangling, and which produces the required stiffness, for example in the case of table linen. Corresponding preparations may also contain other typical ingredients of so-called laundry aftertreatment preparations which improve, for example, the so-called feel or the ironing behavior of the laundry. To make it easier to add in the right quantity and also to handle, it is of advantage to use laundry starch in liquid form. This applies in particular to the use of laundry starch in institutional laundries where predissolved active substances, so-called stock liquors, are normally introduced automatically by pumps into the washing drums or into the particular section of a multiple-compartment batch washing machine. From this arises one of the requirements which the preparation according to the invention is expected to satisfy, i.e. its ability to form a stock liquor or, in other words, its stability in storage after dilution with water. This applies both to the physical stability, i.e. the avoidance of phase separation, such as the sedimentation of starch, and to the microbiological stability of the suspensions. Preparations which contain starch—a readily biodegradable material—are susceptible to infestation by microorganisms. This problem is aggravated by the need arising in institutional laundries to use stock liquors which are normally stored for several days in storage containers and which are added from those containers. Even though microbial infestation may not impair the effectiveness of the starch suspensions, it is unacceptable, particularly in the case of germs to which human beings are susceptible, because of course the laundry starch remains on the treated textile and comes into contact with human beings.
2. Disclosure of Related Art
It is known that the separation of starch from the suspension can be avoided by using a so-called carrier liquor, for example an aqueous solution of carboxymethyl cellulose. However, in order to keep a large amount of starch suspended, as required by the user, the concentration of carboxymethyl cellulose has to be so high that the handling of the laundry starch concentrate is complicated by the thickening effect of the carboxymethyl cellulose. If a starch suspension pregelatinized by brief heating, for example to between 40 and 60° C., is used, difficulties arise out of the fact that, where carboxymethyl cellulose is used, the preparation thickens considerably after only a short time.
German patent 1 940 655 describes starch suspensions which contain a solution of xanthan gum and/or water-soluble derivatives of xanthan gum as their aqueous phase. The starch is effectively prevented from sedimenting in this way.
To increase stability to microorganism infestation, it is proposed in the cited document to use conventional disinfectants, such as formaldehyde. Since disinfectants such as formaldehyde also remain on the starched laundry, there is again a risk of their coming into contact with. and affecting the user. Consequently, formaldehyde and other aldehydes, phenols and substances which release active chlorine cannot be used despite their favorable antimicrobial activity.
Accordingly, the problem addressed by the present invention was to provide a preservative for laundry starch concentrates which, on the one hand, would reliably prevent microbial infestation of the laundry starch concentrate and the aqueous stock liquor prepared therefrom and which, on the other hand, would not remain on the starched laundry in quantities or activities likely to affect the user.
DESCRIPTION OF THE INVENTION
This problem has largely been solved by the use of a combination of ethanol and a quaternary ammonium compound corresponding to general formula (I):
R
1
R
2
(CH
3
)
2
N
+
A
−
(I)
in which R
1
and R
2
independently of one another represent a linear or branched alkyl group containing 8 to 18 carbon atoms, more particularly 8 to 10 carbon atoms, and A
−
is a charge-equalizing anion, such as halide (for example chloride, bromide, iodide, fluoride), methosulfate or ethosulfate, for preserving aqueous laundry starch concentrates which contain starch or starch derivatives suspended in an aqueous xanthan solution.
In the combination to be used in accordance with the invention, the ratio by weight of the components ethanol to quaternary ammonium compound is preferably 5,000:1 to 1:1 and, more preferably, 400:1 to 10:1. The combination to be used in accordance with the invention is preferably present in liquid form and may contain other ingredients emanating, for example, from the particular form in which the components are supplied. Thus, besides water, ethanol often contains so-called denaturing agents, such as methyl ethyl ketone, while quaternary ammonium compounds are commercially available in the form of preparations which, besides water, contain other lower alcohols than ethanol, for example isopropanol.
The combination to be used in accordance with the invention is preferably used in quantities of 1 part by weight to 10 parts by weight and more preferably in quantities of 2 parts by weight to 8 parts by weight, based on 100 parts by weight of the liquid laundry starch concentrate as a whole, for preserving the concentrate.
The present invention also relates to a liquid laundry starch concentrate which contains starch or starch derivatives suspended in an aqueous xanthan solution and which is characterized in that it contains ethanol and a quaternary ammonium compound corresponding to general formula (I):
R
1
R
2
(CH
3
)
2
N
+
A
−
(I)
in which R
1
and R
2
independently of one another represent a linear or branched alkyl group containing 8 to 18 carbon atoms, more particularly 8 to 10 carbon atoms, and A
−
is a charge-equalizing anion, such as halide (for example chloride, bromide, iodide, fluoride), methosulfate or ethosulfate. Ethanol is present in the preparations according to the invention in quantities of preferably 1% by weight to 10% by weight and, more preferably, 2% by weight to 8% by weight whereas the quaternary ammonium compound corresponding to general formula I is present in quantities of preferably 0.002% by weight to 0.5% by weight and, more preferably, 0.02% by weight to 0.2% by weight. In the quaternary ammonium compounds corresponding to general formula I, R
1
is preferably identical with R
2
. Preferred alkyl groups R
1
and R
2
are decyl groups, more particularly n-decyl groups. Ethanol and the quaternary ammonium compound of general formula I may be incorporated in the preparations according to the invention in the form of the combination to be used in accordance with the invention or separately.
The starch used may be selected from any of the starches and starch derivatives present in granular or powder form, for example corn starch, rice starch, potato starch and/or tapioca starch. It is preferably present in native form although it may also be thermally, hydrolytically or oxidatively degraded. Starches in the context of the present invention also include any starch derivatives which are largely insoluble in cold water and which gelatinize in hot water. Starch is present in the preparations according to the invention in quantities of preferably 10% by weight to 50% by weight and more preferably 20% by weight to 45% by weight.
For stabilization against the sedimentation of starch, the aqueous preparations
Brunsman David
Henkel Ecolab GmbH & Co OHG
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