Dispensing – Processes of dispensing
Patent
1996-10-28
1998-06-16
Stucker, Jeffrey
Dispensing
Processes of dispensing
222101, B67B 700
Patent
active
057657246
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method for emptying a substantially completely compressible container filled with a thixotropic (pseudoplastic) paste, more particularly a paste-form detergent. The container is more particularly a bag of a flexible material.
BACKGROUND OF THE INVENTION
Paste-form, substantially water-free detergents are mainly used in institutional laundries. Examples of such pastes are described in DE 38 26 110 A1 and in DE 37 19 906 A1. Their advantages lie in their high washing power by virtue of the high concentration of washing-active components in relation to powder-form detergents because non-washing-active additives serving merely to condition the detergent are not necessary in their case.
However, problems are posed by the physical properties of the pastes, namely their high viscosity and, in particular, their thixotropic (pseudoplastic) behavior which is an obstacle to easy emptying and metering of the paste. By thixotropy is meant the reduction in viscosity which occurs when the paste is stirred, shaken or otherwise sheared and the subsequent gradual increase in the viscosity of the unmoved paste. At room temperature, the viscosity of the above-mentioned pastes is so high that they are not able to flow from the storage container--or not in the time and quantity necessary for the intended application--under the sole influence of gravity.
Methods and devices for removing detergent pastes from containers are described inter alia in DE 37 19 906 A1, in DE 38 26 110 A1 and in German Utility Model G 93 14 591. According to this prior art, a drum is used as the storage container for the paste-form detergent. A plate ("follower plate") which is designed to move in the drum, extending up to the wall thereof, applies pressure to the paste and enables it to be transported by pump through a simple tube (DE 37 19 906 A1 and DE 38 26 110 A1). This emptying method is suitable for pastes with a viscosity of around 75,000 to 90,000 mPa.s. For pastes with higher viscosities, for example from 150,000 to 250,000 mPa.s, G 93 14 591 proposes a stirrer beneath the follower plate which liquefies the paste under the follower plate and thus makes it easier to dispense.
These known emptying methods and devices are designed for drums, i.e. relatively large containers. They are also suitable in principle for emptying relatively small paste containers holding up to about 30 kg but are uneconomical in this case. In addition, there is the further cost factor that, to avoid packaging waste, the drums have to be cleaned and returned to the detergent manufacturer. In the case of small containers, the cost of reusable containers is particularly high measured against the holding capacity of the container. On the other hand, however, economic reuse or recycling of the container should be possible in their case, too.
A device for substantially completely emptying flexible disposable containers filled with fluids is known from DE 42 18 297 A1. The relatively flat bag of wedge-shaped cross-section has an upper outlet opening. For emptying, it is placed between two plates and the outlet opening is connected to a tube. By means of a pressure cylinder, the plates are moved towards one another and the fluid accommodated in the container is squeezed out.
However, this emptying method is unsuitable for bags filled with thixotropic pastes because the pressure acting over the entire upper surface of the container is generally not sufficient for completely and sufficiently liquefying the paste. Accordingly, where this method is applied to bags filled with the above-mentioned paste, only part of the paste can be emptied. A large proportion of the paste remains in the container.
The problem addressed by the present invention was to develop a method for substantially completely emptying small inexpensive containers without the operator coming into contact with the product. In addition, the packaging problem mentioned above was to be economically solved. It was also to be possible to carry out the method with
REFERENCES:
patent: 4087831 (1978-05-01), Bendoni
patent: 4889644 (1989-12-01), Amberg et al.
Amberg Guenther
Huber Wolfgang
Henkel-Ecolab GmbH & Co OHG
Jaeschke Wayne C.
Robbins Frank E.
Stucker Jeffrey
Szoke Ernest G.
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