Chemistry: analytical and immunological testing – Condition responsive control
Patent
1995-02-24
1996-03-12
Skane, Christine
Chemistry: analytical and immunological testing
Condition responsive control
436 52, 436164, 436175, 25217417, 252DIG1, 252DIG14, 2524081, G01N 3100, G01N 3300, G01N 3508, G01N 100
Patent
active
054985463
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a washing process in which the concentration of the wash liquor is determined by analysis.
2. Discussion of Related Art
In the machine washing of laundry, it is desirable, above all in the institutional sector, completely or partly to automate dosage of the detergent in the preparation or regeneration of the wash liquor. To control dosage according to requirements, it has proved to be useful to employ not only external parameters, but also the actual concentration of washing-active substance in the liquor as a guide for subsequent dosage of the detergent. The necessary dosage is thus the difference between the required concentration and actual concentration of washing-active substance. Control methods such as these are today mainly used in batch washing machines, the fact that the total conductivity of the liquor increases with increasing concentration being used to determine the content of washing-active substance in the liquor. The connection between conductivity and concentration of washing-active substances has to be empirically determined for each new composition of a detergent. With this system, difficulties arise out of the highly variable input of electrolytes with the soiled washing which leads to inaccurate analysis results and hence to incorrect dosage. In addition, DE-OS 29 49 254 describes a process in which the concentration of wash liquors and cleaning solutions is photometrically determined through the content of fluorescent dyes. The disadvantage of this process lies in the tendency of all dyes to be adsorbed onto textile fibers from solution so that the wash liquor loses these dyes more quickly than the other active substances. Since, in addition, dye adsorption also depends on the quality of the fibre material, the concentration of washing-active substances cannot be reliably determined in this way. Accordingly, for more reliable dosage of the detergent, efforts have long been made to find a process which would not be affected by such factors.
DESCRIPTION OF THE INVENTION
A correspondingly improved process has now been found.
The present invention relates to a washing process using an aqueous solution of washing-active substance, in which the concentration of washing-active substance in the solution is indirectly determined by determining the content of a reducing sugar which is added during preparation of the wash liquor in a quantity proportional to the quantity of washing-active substance. In a preferred embodiment, the sugar has been added in a certain constant ratio to the washing-active substance or to the mixture of several washing-active substances, i.e. the detergent, before preparation of the actual wash liquor.
In the context of the present application, washing active substances are principally surfactants and builders, but also for example redeposition inhibitors, bleaching agents, enzymes, detergency boosters and antimicrobial agents.
Glucose is preferably used as the reducing sugar.
The use of a reducing sugar as a tracer not only solves the problems of known concentration measuring processes, because reducing sugars are neither carried over into the wash liquor nor adsorbed onto textile fibers in significant amounts, it also affords unexpected advantages in the analysis itself. Thus, it has been found that these compounds can be determined largely independently of the other detergent ingredients in the wash liquor and that their determination can be completed so quickly that the result may be used to control ongoing processes. In addition, sugars are biodegradable and toxicologically safe and do not affect the washing process.
The quantity of sugar which has to be added to the wash liquor depends primarily on the sensitivity with which the compound used can safely be analytically determined under these conditions. The quantity to be selected does of course also depend to a large extent on the analysis technique. In the case of the reducing sugars used in accordance with the invention, the i
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Kling Hans-Willi
Kuhlmann Werner
Grandmaison Real J.
Hailey Patricia
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Skane Christine
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