Coating processes – With stretching or tensioning
Patent
1989-09-18
1991-01-01
Pianalto, Bernard
Coating processes
With stretching or tensioning
427209, 427210, 427231, 427276, 427278, 427365, 4273855, 4274301, B05D 312, B05D 100, B05D 722
Patent
active
049817213
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a process for the manufacture of stretch resistant, liquid impermeable, flexible press bands, especially for dewatering presses of paper-making machines according to the preamble of claim 1, as well as an apparatus for practising that process.
Press bands which are manufactured according to that process are known from German published application (DE-OS) No. 32 24 760. They are usually coated by pouring a plastic material onto a reinforcing structure, so that the reinforcing elements of the reinforcing structured web are at least partly imbedded into the plastic material.
According to German published application (DE-OS) No. 33 18 984 the plastic material is poured in such a way that the pouring jet strikes the reinforcing fabric band covering a horizontal cylinder which rotates about its longitudinal axis moving slowly and parallel to the cylinder axis, or the pouring of the plastic material is practised such that the pouring jet enters a vertically or inclined positioned mold, containing the reinforcing fabric band in form of one or several fabric layers of threads consisting of one or more materials such as polyamide, polyester, Kevlar, metal and others or mixtures thereof.
The above mentioned process is disadvantageous therein that a press band which has been coated in such a way is provided with a smooth outer surface, whereas the inner surface of the band is provided with the requested hollow spaces and/or depressions for feeding away the liquid. In order to make possible the use of such a manufactured press band on a dewatering press the band must be turned around after its removal from the mold in order to put the structured surface of the band corresponding originally to the inner surface of the band outwardly or to change the inner surface of the band to become the outer surface of the band, whereas the smooth surface becomes the inner surface of the band. This is because the structured outer surface of such press bands opposing to the bandlike fiber material or opposing to the felt fabric serves for the removal of the liquid. The turning around of finished poured press bands, however, is especially in cases of small band diameters very problematical and requests doubtlessly an essential effort, moreover not excluding the risk that the press band is damaged during such a turning around operation.
It has therefore also been proposed to avoid the turning around of the band completely and instead thereof to grind or cut the required dewatering channels into the smooth outer surface of the press band. This kind of manufacturing, however, is a time and cost consuming procedure.
The object of the invention is therefore to be seen therein to amend the process of the above mentioned type such that those press bands, especially extended nip-press bands, which must be provided on the surface opposing to the press felt with hollow spaces and/or depressions for the dewatering of the liquid, can be manufactured in an essentially simpler way without requesting for that purpose costs concerning the apparatus which are inadequately high. The apparatus which must also be developed for that purpose should correspond to that requirement.
The object is solved according to the invention by guiding the reinforcing web band over a roll equipment provided with at least two distantly arranged rolls positioned parallel to one another and one over the other or adjacent to one another, wherein the surface of the band is coated through at least one nozzle on the outer side of the band or inner side of the band or on both sides of the band by a flowable mixture of a prepolymer.
In order to pratice the process according to the invention an apparatus is used, characterized by a roll equipment provided with at least two rolls distantly arranged in parallel one over the other or adjacent to one another, at least one of said rolls is driven, and further characterized by a coating equipment provided with at least one mixing head for the coating material, especially a prepolymer, which coating equipment having
Joos Heinz
Krenkel Bernhard
F. Oberdorfer GmbH & Co. KG Industriegewebe-Technik
Pianalto Bernard
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