Coating apparatus – Immersion or work-confined pool type – Work-confined pool
Patent
1987-05-04
1990-03-27
Beck, Shrive
Coating apparatus
Immersion or work-confined pool type
Work-confined pool
118413, B05C 502
Patent
active
049110977
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an arrangement for the coating of a running material web.
Paper, cardboard etc. are normally produced from natural cellulose fiber. The paper production is a complicated process, which is started by the defibration of natural logs or other plant parts, fibre preparation and finally sheet formation. In the sheet formation one strives to distribute the fibers so evenly as possible. Along with the dewatering, which is carried out by the sheet formation, the fibers are guided more near to each other and are linked, mainly through fluidum bonds.
The paper comprises fibres located in several layers, arbitrarily distributed. If one examines the paper through a magnifying glass, cavities are found between the fibers and the surface is found uneven - everything depending on the micro structure quoted above.
One might have different reasons for the desire to improve this uneven micro structure. One might have, for instance, the desire to reduce the porosity in the paper, in order to be able to apply it as packaging material. Or, it is also important to improve the paper surface itself, in order to be able to print on the paper with a good result. A common method for the surface levelling and the porocity reducing is the application of a layer on the top of the completed paper surface. A normal method is to mix finely divided pigment, for instance clay, to supply this paste on the paper web. The surface smoothness is realized in that one doctors the paste by a trowel blade, a so called scraper knife. The doctored paper is hereafter dried, whereby the supplied paste is attached at the paper web through a certain penetration.
A normal coating method is the guiding of the paper web through a nip located between two drums, in which the paste is supplied by the partial immersion of the other drum in a machine bin filled with paste. The paste excess is doctored off hereafter at a certain distance from the nip and the paste is levelled by a scraper knife. The drum nip can also be replaced by a fountain or a so-called applicator.
Normal web speeds are 600-1000 m/min but even higher speeds, up towards 2000 m/min are applied. The paste excess during the doctoring is hereby often 10-20 ggr. This excess amount is resupplied in to a trough for the return to the machine bin.
A nip method has been developed during the past years, which combines the fountain application and the doctoring in to one member the so-called short dwell technique. A benefit hereby is the short distance between the paste application and the doctoring.
The so far constructed short dwell appliances comprise a defect, which is the minor paste excess amount realized. This is a result of the applied technique, in which the eventual paste excess amount must be compressed out at the rear wall against the running direction of the paper web. This results even in a prolonged penetration extent than was intended for.
SUMMARY
The object of the invention is to realize a development of the familiar short dwell appliances so, that the amount of the paste excess, which is supplied on the web, can be increased. An object is also to realize an application with a favourably short penetration extent. A further object is to create an arrangement in which the application paste flow is smoothly arranged in the application arrangement and air bubbles in the paste can be separated before the paste reaches the running web.
In accordance with the invention, a big amount, in comparison to that paste amount attached at the web, of application paste is supplied on the web in the application chamber. The application chamber is divided by a distributor in an inlet and an exit channel. The paste is supplied on the web thereat, where the latter arrives in the application chamber, after which the paste follows along with the web to a doctor, which forms the front wall of the chamber, at which the excess paste is removed and guided in to the exit channel of the application chamber, for a resupply in the process. The application of the p
REFERENCES:
patent: 3518964 (1970-07-01), Nagler
patent: 4396648 (1983-08-01), Holt et al.
patent: 4452833 (1984-06-01), Holt
patent: 4594963 (1986-06-01), Krautzberger
patent: 4791879 (1988-12-01), Eklund et al.
Bashore Alain
Beck Shrive
LandOfFree
Short dwell application with big excess paste amount does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Short dwell application with big excess paste amount, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Short dwell application with big excess paste amount will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1643741