Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2001-03-29
2004-01-27
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S351000, C510S353000, C510S356000, C510S357000, C510S495000, C510S535000
Reexamination Certificate
active
06683042
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for preparing surfactant granules. It relates in particular to a process which permits the preparation of surfactant granules or surfactant components of laundry detergent and cleaning product compositions, or complete laundry detergent and cleaning product compositions, without spray drying steps or with reduced use of such steps.
BACKGROUND OF THE INVENTION
Granular laundry detergent and cleaning product compositions or components thereof are to a large extent prepared by spray drying. In the course of spray drying, the ingredients such as surfactants, builders etc. are mixed with from about 35 to 50% by weight of water to form an aqueous suspension, known as the slurry, and this slurry is atomized in spraying towers in a stream of hot gas to form the laundry detergent and cleaning product particles. Both the plants for this process and the implementation of the process are costly, since the majority of the slurry water must be evaporated in order to obtain particles having residual water contents of around 5 to 10% by weight. Moreover, the granules prepared by spray drying, although usually of excellent solubility, have low bulk densities, leading to higher packaging volumes and also transport and storage capacities. The flowability of spray-dried granules, also, is not optimal owing to their irregular surface structure, which affects their visual appearance. Spray drying processes have a further series of disadvantages, so that there has been no lack of attempts to carry out the preparation of laundry detergents and cleaning products entirely without spray drying, or at least to minimize the fraction of spray drying products in the finished product.
For instance, W. Hermann de Groot, I. Adami, G. F. Moretti “
The Manufacture of Modern Detergent Powders
”, Hermann de Groot Academic Publisher, Wassenaar, 1995, page 102 ff. describes various mixing and granulating processes for the preparation of laundry detergents and cleaning products. These processes have the common feature that premixed solids are granulated with the addition of the liquid ingredients, and the granules are subjected, if desired, to subsequent drying.
In the patent literature as well there exists a broad prior art on the nontower preparation of laundry detergents and cleaning products. Numerous publications may be found in particular in relation to different apparatuses which are operated under varying conditions, to different granulating auxiliaries and their application to solids charged to a mixer, and to combinations of ingredients with physical conditions to be observed in the course of granulation.
For instance, the European patent EP 642 576 (Henkel) describes a two-stage granulation in two mixer/granulators positioned in series, 40-100% by weight, based on the overall amount of the constituents used, of the solid and liquid constituents being pregranulated in a first, low-speed granulator and the pregranulated product being mixed if appropriate with the remaining constituents and converted to granules in a second, high-speed granulator, observing the following process parameters: granulation in the first mixer at peripheral tool speeds of 2-7 m/s for 0.5-10 min, in the second mixer at peripheral speeds of 8-35 m/s for 0.1-30 (0.5-2)s; temperature of the pregranulated product on entry into the second granulating stage of 30-60° C.
In accordance with the teaching of European patent EP 560 802 (Henkel), zeolite granules comprising surfactant and with bulk densities of from 750 to 1000 g/l may be prepared by using as granulating fluid a mixture of water, surfactants and (co)polymeric carboxylates, the surfactant content of the granulating fluid being at least 10% by weight. In accordance with the teaching of this document, the granulating fluid is supplied through a spraying nozzle.
The European patent application EP-A-0 402 111 (Procter & Gamble) discloses a granulation process for preparing surfactant granules, in which surfactants, water and, optionally, fine powders are mixed to a paste which is granulated in a high-speed mixer by the addition of a “deagglomerating agent” (finely divided powder).
The European patent application EP-A-0 508 543 (Procter & Gamble) specifies a process in which a surfactant acid is neutralized with an excess of alkali to give a surfactant paste with a concentration of at least 40% by weight, which is subsequently conditioned and granulated, direct cooling taking place using dry ice or liquid nitrogen.
Surfactant mixtures which are subsequently applied to solid absorbents and provide laundry detergent compositions or components thereof are also described in EP 265 203 (Unilever). The liquid surfactant mixtures disclosed in this document comprise sodium salts or potassium salts of alkylbenzenesulfonic acids or alkylsulfuric acids in amounts of up to 80% by weight, ethoxylated nonionic surfactants in amounts of up to 80% by weight, and not more than 10% by weight of water.
Similar surfactant mixtures are also disclosed in the earlier EP 211 493 (Unilever). According to the teaching of this document, the surfactant mixtures for spray application contain between 40 and 92% by weight of a surfactant mixture and also more than 8 up to a maximum of 60% by weight of water. The surfactant mixture consists in turn of at least 50% of polyalkoxylated nonionic surfactants and ionic surfactants.
The European patent EP 772 674 (Henkel KGaA) describes a process for preparing surfactant granules by spray drying, in which anionic surfactant acid(s) and highly concentrated alkaline solutions are exposed separately to a gaseous medium and are mixed in a multifluid nozzle, neutralized and spray-dried by spraying into a stream of hot gas. The finely divided surfactant particles obtained in this way are subsequently agglomerated in a mixer to give granules having bulk densities above 400 g/l.
DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a process which permits the preparation of surfactant granules for laundry detergents and cleaning products without using spray drying steps or with reduced use of spray drying steps. The process to be provided should be suitable for universal use and with regard to the solids and granulating fluids that can be employed should be subject to as few restrictions as possible, while substantially avoiding the disadvantage of energy-consuming water evaporation.
These various objects are achieved in a mixing and granulating process in which a flowable component comprising surfactant is foamed by exposure to a gaseous medium to form a foam which acts as granulating auxiliary. The invention accordingly provides a process for preparing surfactant granules in which a flowable component comprising surfactant is exposed to a gaseous medium, the flowable component comprising surfactant being foamed by the gaseous medium, and the resulting surfactant foam subsequently being applied to a bed of solids charged to a mixer.
In comparison with the use of conventional granulating fluids, the process regime of the invention has considerable advantages. Through use of a “granulating foam” instead of conventional granulating fluids the distribution of liquid from the bed of solids is significantly more homogeneous. The particles of the bed of solids are wetted more effectively, and overall less granulating fluid is needed to form the granules, so that subsequent drying steps may be omitted. A further advantage is the more homogeneous particle size distribution of the resulting granules, since the use of the granulating foam prevents excessive agglomeration and the formation of lumps. Additionally, dust fractions and fine fractions are bound more effectively, so that the yields of granules in the desired particle size range (from about 400 to 1600 &mgr;m) are significantly improved in relation to conventional liquid granulations. In contrast to the conventional granulation with granulating fluids which have to be atomized or sprayed, the process of the invention also permits the use
Larson Bernd
Raehse Wilfried
Semrau Markus
Sunder Matthias
Douyon Lorna M.
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien (Henkel KGaA)
Murphy Glenn E. J.
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