Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2001-03-07
2002-12-10
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S441000, C264S117000
Reexamination Certificate
active
06492319
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a process for producing high density detergent compositions having improved physical properties. More particularly, the invention is directed to a continuous process during which high density detergent agglomerates are produced by feeding a surfactant paste and dry starting detergent material directly into a cylindrically-shaped/moderate speed mixer/densifier having a centrally positioned rotating shaft and at least one high speed chopper or cutter. The process produces an improved free flowing, high density detergent composition with a narrow particle size distribution which can be commercially sold as a low dosage or “compact” detergent composition.
BACKGROUND OF THE INVENTION
Recently, there has been considerable interest within the detergent industry for laundry detergents which are “compact” and therefore, have low dosage volumes. To facilitate production of these so-called low dosage detergents, many attempts have been made to produce high bulk density detergents, for example with a density of 600 g/l or higher. The low dosage detergents are currently in high demand as they conserve resources and can be sold in small packages which are more convenient for consumers.
Generally, there are several types of processes by which detergent granules or powders can be prepared. One type of process involves spray-drying an aqueous detergent slurry in a spray-drying tower to produce highly porous spray dried particulate material. In another type of process, various detergent components are dry mixed after which they are combined together with a binder such as a nonionic or anionic surfactant. In both processes, the most important factors which govern the density of the resulting detergent granules are the density, porosity and surface area of the various starting materials and their respective chemical composition. These parameters, however, can only be varied within a limited range. Thus, a substantial bulk density increase can only be achieved by additional processing steps which lead to densification of the detergent granules.
There have been many attempts in the art for providing processes which increase the density of detergent material. Particular attention has been given to densification of spray-dried particulate material by post tower treatment. For example, one attempt involves a batch process in which spray-dried or granulated detergent powders containing sodium tripolyphosphate and sodium sulfate are densified and spheronized in a Marumerizer®. This apparatus comprises a substantially horizontal, roughened, rotatable table positioned within and at the base of a substantially vertical, smooth walled cylinder. This process, however, is essentially a batch process and is therefore less suitable for the large scale production of detergent powders. Other attempts have been made to provide a continuous processes for increasing the density of “post-tower” or spray dried particulate material.
All of the aforementioned processes are directed primarily to densifying or otherwise processing spray dried particulate material. Currently, the relative amounts and types of materials subjected to spray drying processes in the production of detergent granules has been limited. For example, it has been difficult to attain high levels of surfactant in the resulting detergent composition, a feature which facilitates production of low dosage detergents. Thus, it would be desirable to have a process by which detergent compositions can be produced without having the limitations imposed by conventional spray drying techniques. To that end, the art is also replete with disclosures of processes which entail agglomerating detergent compositions. For example, attempts have been made to agglomerate detergent builders by mixing zeolite and/or layered silicates in a mixer to form free flowing agglomerates.
However, in all of the aforementioned processes, continuous large-scale production has its difficulties, especially relative to obtaining acceptable product consistently and with minimal wear and tear on the manufacturing equipment. For instance, while certain mixer/densifiers work extremely well at the lab scale, their performance is not always reproducible in large-scale commercial continuous manufacturing facilities. One problem experienced with large-scale detergent manufacturing using the aforementioned processes involves detergent product that has a wide particle size range. This, in effect, produces a detergent product having some “undersized” or very “fine” particles and some very large or “oversized” particles which is not only unacceptable to the consumer, but leads to product performance inconsistencies. Specifically, a particular dose or scoop of detergent product used by the consumer may not have the targeted ingredient levels because a disproportionate amount of “fines” or “overs” is in the dose as a result of the settling of the fines to the bottom of the product box during storage and handling. This inevitably leads to undesirable cleaning performance, and at a minimum, inconsistencies including performance. One solution to this problem is simply to recycle the “fines” and grind the “overs” to the desired size, but this increases the manufacturing costs significantly.
Another problem that has arisen involves excessive vibration of the rotating shafts in commercial scale mixer/densifiers, especially in large moderate speed mixer/densifiers, which can have deleterious effects on the detergent composition produced as well as on the mixer/densifiers and other closely located manufacturing equipment. This problem can also lead to structural damage to the manufacturing building for which substantial expenditures may be required for repairs. The use of additional mechanical apparatus such as tuned dampers positioned on the shaft only add to the cost of manufacturing and can interfere its with operation in that the tuned damper apparatus inside the mixer provides a place for detergent to accumulate, thereby deleteriously affecting mixer operation. Thus, there remains a need for a means by which commercial scale moderate speed mixer/densifiers used to produce low dosage, high density detergent compositions can be operated continuously without significant mechanical vibration and damage resulting therefrom.
Accordingly, there remains a need in the art to have a process for continuously producing a high density detergent composition which has improved physical properties including a more narrow particle size distribution. There is also a need for such a process that involves a moderate speed mixer/densifier that experiences minimal mechanical vibration, and yet, produces a superior detergent composition. Also, there remains a need for such a process which is more efficient and economical to facilitate large-scale production of low dosage or compact detergents.
BACKGROUND ART
The following references are directed to densifying spray-died particulate material: Appel et al, U.S. Pat. No. 5,133,924 (Lever); Bortolotti et al, U.S. Pat. No. 5,160,657 (Lever); Johnson et al, British patent No. 1,517,713 (Unilever); and Curtis, European Patent Application 451,894. The following references are directed to producing detergents by agglomeration: Capeci et al, U.S. Pat. No. 5,366,652; Capeci et al, U.S. Pat. No. 5,486,303; Capeci et al, U.S. Pat. No. 5,489,392; Capeci et al, U.S. Pat. No. 5,516,448; Beerse et al, U.S. Pat. No. 5,108,646 (Procter & Gamble). Other relevant prior art includes: PCT Publication WO 98/14558; PCT Publication WO 98/14557; PCT Publication WO 98/14556; PCT Publication WO 98/14553; PCT Publication WO 98/14552; PCT Publication WO 98/14555; PCT Publication WO 98/1454; PCT Publication WO 98/1455 1; and PCT Publication WO 98/11193 and WO 98/24876.
SUMMARY OF THE INVENTION
The present invention meets the aforementioned needs in the art by providing a process which continuously produces a high density detergent composition via a process during which high density detergent agglomerates are produced by feeding a surfactant pas
Angell Adrian John Waynforth
Nassano David Robert
Corstanje Brahm J.
Douyon Lorna M.
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
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