Compositions – Dust suppressants for bulk materials – or processes of...
Patent
1994-12-09
1996-03-26
Lieberman, Paul
Compositions
Dust suppressants for bulk materials, or processes of...
252 91, 252174, 25217413, 252135, C11D 1100, C11D 1706
Patent
active
055018106
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION AND FIELD OF THE INVENTION
This invention relates to a process for the production of granular detergents which are primarily intended for washing laundry.
DISCUSSION OF THE RELATED ART
Detergents, above all those intended for use in the home, are generally marketed not as mixtures of their constituents, but rather in the form of granular preparations in which all the constituents or the majority of constituents are present in the form of an intimate mixture in the individual particles. This form has various advantages in the practical application of the detergents, of which only the substantial absence of dust and the safeness against separation during transport are mentioned here. Granular detergents of the type in question can be produced in various ways. Thus, processes are known in which the individual constituents of the detergents are converted into the granular form by compacting granulation, for example using extruders. There are also processes in which the fine-particle constituents are agglomerated to form relatively large particles with the aid of liquids, for example alkali metal silicate solutions (U.S. Pat. No. 4,207,197, U.S. Pat. No. 4,996,001). For various technical reasons, the process of spray drying has long been preferred for the continuous production of relatively large quantities of granular detergents. In this process, which is carried out in large towers, an aqueous slurry of the detergent ingredients is dried in free fall by hot gases to form granular products. Apart from the fact that they are easy to produce in large quantities, these products also have various applicational advantages over detergents produced by other methods. However, it has recently been found to be a disadvantage that granular detergents produced by spray drying generally have only low apparent densities of rarely more than 550 g/l because this necessitates relatively large containers and a large amount of packaging material. Accordingly, increasing efforts have been made in recent years to find ways of retaining the advantages of spray drying while at the same time increasing the apparent densities of the spray-dried products. For example, it is proposed in European patent application 337 330 to spray the spray-dried granular detergents with nonionic surfactants in a high-speed mixer. The increase in apparent density is dependent upon the quantity of nonionic surfactant applied and is remarkably large when the tower powder used is very light. Unfortunately, a disadvantage of this approach is that, when relatively large quantities of nonionic surfactants are applied, the products obtained show poor flow properties or are tacky so that increases in apparent density by this method are limited.
The problem addressed by the present invention was also to produce a spray-dried detergent of relatively high apparent density by a process which would not be attended by any of the disadvantages of known processes .
DESCRIPTION OF THE INVENTION
The present invention relates to a process for increasing the apparent density of spray-dried detergents in which the spray-dried granular material is simultaneously or successively sprayed in a mixing unit with a liquid nonionic surfactant and an aqueous solution of an alkali metal silicate. This process is preferably carried out in a mixing unit comprising a horizontally mounted cylindrical mixing drum in which mixing tools rotate on a horizontal shaft.
The process according to the invention is distinguished from known processes by the fact that the use of silicate solution makes it possible to obtain a further increase in apparent density without the particles formed becoming tacky. Surprisingly, the granular detergent flows freely immediately after leaving the mixing unit without any need for a separate drying step.
The process according to the invention is suitable for spray-dried detergents of any composition, although it is preferably carried out with detergent tower powders which already have a relatively high apparent density. In a part
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Buser Beat
Eugster Hans
Reuter Herbert
Douyon Lorna M.
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Lieberman Paul
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