Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2000-01-14
2002-07-23
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S507000, C510S509000, C264S117000
Reexamination Certificate
active
06423679
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a process for increasing surfactant paste content in high density detergents. More particularly, the process involves first injecting surfactant paste into starting detergent materials and agglomerating the mixture, then allowing the agglomerated mixture to age for a specified period of time. After the aging period, incremental amounts of additional surfactant paste are injected into the mixture until the paste capacity of the detergent agglomerates is maximized. Detergent agglomerates produced by the process have surfactant levels in excess of 45% by weight.
BACKGROUND OF THE INVENTION
There has been considerable interest of late in the detergent industry in “compact” detergents. In various countries around the world, compact detergents are increasingly popular with consumers because they are less bulky than conventional detergents, and thus easier to transport from the store to the home. Compact detergents are also easier for consumers to use because less detergent is needed for a typical dosage in a laundry machine. Compact detergents are advantageous not only to consumers, but also to detergent manufacturers because they provide cost savings achieved through decreased packaging requirements. In addition, the smaller detergent packages are seen as more “environmentally friendly”. These benefits to consumers and manufactures have stimulated strong interest within the detergent industry to find improved methods of manufacturing compact detergents.
Generally, there are two primary processes by which detergent granules or powders are manufactured. The first type of process involves spray-drying an aqueous detergent slurry in a spray-drying tower. Usually, the detergent slurry enters the tower from the top and mixes with a counterflow stream of hot air that evaporates the excess water. This process produces light, highly porous, low-density detergent granules. In the second type of process, various powdered detergent ingredients are dry mixed with a binder, such as a nonionic surfactant, and agglomerated into larger detergent granules. The mixing and agglomeration are normally accomplished by passing the detergent powders and binder through a high-speed mixer/densifier and a moderate-speed mixer/densifier in series. The agglomeration process is recognized as one of the more feasible methods of manufacturing highly dense detergents, and much of the efforts to improve the manufacture of compact detergents have centered around it.
One of the factors that limits the density of detergent granules produced by an agglomeration process is the amount of surfactant the granules can hold. Under typical agglomeration operations, there is a critical surfactant saturation point which cannot be exceeded. If this saturation point is exceeded and too much surfactant paste is mixed with the starting detergent powders, the detergent mixture will cake and gum up. Caking of the powder/binder mixture can produce detergent clumps that tend to smear onto the blades and wall of the mixer/densifier, resulting in increased friction and power draw. In addition, excess caking of the detergent mixture can lead to an uncontrolled soap buildup between the mixer blades and the wall of the mixing vessel that can cause damaging vibrations during operation of the machinery. Yet another problem with exceeding the surfactant levels saturation point is that the flowability of the agglomerated detergent granules can be impaired due to stickiness from the typically oily surfactant.
Accordingly, there is a need within the detergent industry for a process of increasing the surfactant content in agglomerated detergent granules so that high density detergents having higher levels of surfactant can be more efficiently manufactured. It is desired that this process yield an agglomerated detergent having excellent flow and handleability. It is further desired that this process not result in caking or clumping of the mixture, and that it be economical to operate in terms of power requirements of mixing and agglomerating the surfactant paste and powders. It is also desired that this process yield high-density detergent agglomerates without causing excess vibration from uncontrolled soap buildup that could destroy costly industrial machinery.
BACKGROUND ART
The following references relate to detergent manufacturing processes: U.S. Pat. No. 5,489,392 (Capeci et al., 1996); U.S. Pat. No. 5,486,303 (Capeci et al., 1996); U.S. Pat. No. 5,366,652 (Capeci et al., 1994); German Patent No. 4216774A1 (Hans-Friedrich Kruse et al., 1993); U.S. Pat. No. 5,160,657 (Bortolotti et al., 1992); U.S. Pat. No. 5,133,924 (Appel et al., 1992); EP 0510746A2 (Goovaerts et al., 1992); and EP 0351937 (Hollingsworth et al., 1989); U.S. Pat. No. 5,149,455 (Jacobs et al., 1992); U.S. Pat. No. 5,009,804 (Clayton et al., 1991); U.S. Pat. No. 4,715,979 (Moore et al., 1987); U.S. Pat. No. 4,637,891 (Dewel et al., 1987); and U.S. Pat. No. 4,006,110 (Kenny et al., 1977).
SUMMARY OF THE INVENTION
The present invention meets the aforementioned needs in the art by providing a process for increasing the total amount of surfactant in an agglomerated compact detergent product. The process involves making multiple injections of surfactant paste into one or more serially positioned mixers/densifiers. An important aspect of the process is that the initially agglomerated detergent powders and paste are aged for a period of time determined by the kinetics of the specific reaction phase transformation. This aging step is performed by either additional mixing after the paste and powders are first combined, or in a separate processing step. After aging, the initial agglomerates are treated with additional incremental surfactant injections until the desired weight fraction of surfactant in the agglomerates is reached. This process resolves a long-felt need in the detergent industry for a method of increasing surfactant levels in compact agglomerates that is workable in large-scale commercial operations. All percentage, ratios, and proportions used herein are by weight unless otherwise indicated; all documents, including patents and publications, cited herein are incorporated by reference.
In accordance with one aspect of the invention, a process for making high-surfactant content detergent agglomerates is provided. Specifically, the process comprises the steps of: (a) agglomerating starting detergent material and a first portion of surfactant paste into a first mixer/densifier so as to form initial agglomerates; (b) aging said initial agglomerates for a predetermined amount of time; (c) mixing said initial agglomerates and a second portion of said surfactant paste into a second mixer/densifier so as to form higher surfactant-containing agglomerates; and (d) repeating said step (c) so as to form said high-surfactant content detergent agglomerates having at least about 45% by weight of surfactant. The surfactant paste used in the process is selected from the group consisting of anionic, cationic, nonionic, zwitterionic, and ampholytic surfactants, and compatible mixtures thereof
In another embodiment of the invention, the starting detergent material comprises from about 1% to about 80% by weight of a detergent aluminosilicate builder and from about 9% to about 60% by weight of sodium carbonate. Mean residence times of the initial agglomerates in the first mixer/densifier range from about 1 second to about 120 seconds, while the mean residence time of the higher surfactant-containing agglomerates in the second mixer/densifier can range from about 1 second to about 30 seconds. Also, the process includes aging the initial agglomerates for at least about 10 seconds before mixing with a second portion of surfactant paste.
In another embodiment of the invention, the initial agglomerates and higher surfactant-containing agglomerates have mean particle diameters of less than about 400 &mgr;m. Further, the high-surfactant content detergent agglomerates have a density of from about 600 g/l to about 850 g/l. In another embod
Capeci Scott William
Hoffman William Marion
Mort, III Paul R
Sullivan Millard Edward
Bolam Brian M.
Douyon Lorna M.
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
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