Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1994-02-18
1996-05-28
Lacey, David L.
Paper making and fiber liberation
Processes and products
Non-fiber additive
162158, 1621812, 162133, 106772, 106653, 156 39, 156 41, 156 42, D21H 1766, D21H 1763, B28B 152, C04B 2814
Patent
active
055207790
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/EP92/01895 filed 20 Aug. 1992 and based, in turn, upon German national applications P 41 27 929.8, P 41 27 930.1 and P 41 27 932.8 of 23 Aug. 1991 under the International Convention.
FIELD OF THE INVENTION
My present invention relates to a process and apparatus for producing files reinforced plaster plates and plasterboard.
BACKGROUND OF THE INVENTION
Various products are generically defined as gypsum-fiber plates or plasterboard (GF-plates), depending on the process by which they have been produced. What they have in common is only the fact that the reinforcement is done by fibers embedded in the gypsum, while in the gypsum-cardboard plates (GK-plates) or plasterboard a cardboard on the surface is the reinforcement element.
The processes for producing fiber-reinforced plaster plates can be categorized as follows:
1) Dry or Semi-dry Processes
These owe their name to the fact that for the formation of the plate a spreadable mix is used, which can be either completely dry, as in German Patent Document 21 03 931 or prewetted in a controlled manner, as described in European Patent Document EP 0 153 588.
The advantages of the dry process are the following:
The technique used is derived from chipboard manufacturing and is therefore a proven technology.
Chipboard technology has shown that a high degree of overall efficiency can be achieved. This is considered essential of the GF-Plate to compete with the GK-plate.
The residual water content to be dried in the plate is comparatively low in comparison with the wet process, which saves on energy costs.
Problems with gypsum-containing water are avoided.
The disadvantages of the dry process are the following:
Dry paper treatment is unsatisfactory. It consumes large amounts of electrical and mechanical energy and in the end delivers a product which is not well suited for reinforcement. As a result the plates have less strength than they should have for a given density and composition.
For the mixing and wetting of a dry GF-mixture no reliable solution has yet been found.
The machinery for the dry process is considerably more complicated and expensive than that required for the wet process, because heavy presses are necessary.
2) Wet Processes
In these processes the plate is formed from a watery suspension of gypsum and fibers and that the excess water is mechanically removed. In this procedure several specific problems arise, the greatest being the poor dewatering capability of the gypsum-fiber suspension, which limits high production output. This is the reason why wet processes have been uneconomical up to now, in spite of the low investment costs.
However wet processes also have very definite advantages.
The paper fiber can be treated much gently and finely in water, so that the amount of fiber required for reinforcement is clearly smaller than with the dry paper process.
There is no known dry mixing process which mixes the fiber and the gypsum as evenly as the mixture in suspension.
The wet fiber stretches and orients itself in the plate plane during dewatering.
As a result of these three facts, the GF-plates produced by the wet process have a clearly higher strength and can be lighter for the same strength than the GK-plates produced by the dry paper method.
The wet paper treatment is a perfectly controlled technology, by contract with the dry paper method.
The wet paper treatment consumes much less electric energy than the dry paper method. This more than compensates for the drawback of higher thermal energy consumption during the drying of the plate.
Wet processes do not require heavy-duty presses, which count for a large part of the investment costs in the dry paper processes. The specific investment costs for wet processes are therefore lower in installations with low output.
However with all the undeniable advantages of the wet processes, one cannot ignore some important disadvantages:
The control of large amounts of gypsum-saturated water is not simple.
Because of
REFERENCES:
patent: 3737265 (1973-06-01), Schafer et al.
patent: 3951735 (1976-04-01), Kondo
patent: 4502901 (1985-03-01), Burkard
patent: 4734163 (1988-03-01), Eberhardt et al.
patent: 4942003 (1990-07-01), Bold
patent: 5015449 (1991-05-01), Koslowski
patent: 5154874 (1992-10-01), Koslowski
patent: 5171366 (1992-12-01), Richards et al.
A New Method for Producing Gypsum Fiberboard at a Dutch Gypsum Plant by J. old, published by 264 Zement-Kalk-Gips (ZKG), 42 (1989) May.
Babcock BSH Aktiengesellschaft Vormals Buttner-Schilde-Haas AG
Dubno Herbert
Fortuna Jos'e A.
Lacey David L.
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