Coating processes – With post-treatment of coating or coating material – Gas jet or blast mechanically treats coating
Patent
1992-01-22
1994-11-29
Savage, Matthew O.
Coating processes
With post-treatment of coating or coating material
Gas jet or blast mechanically treats coating
427428, 118 63, 118246, 118262, B05D 128, B05D 304
Patent
active
053688937
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of PCT/EP91/00596 filed 27 Mar. 1991 and based upon a German Application P 40 14 463.1 filed 7 May 1990 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a device for coating a material web, especially a cardboard web and more particularly for the coating of cardboard with a voluminous application of a uniform covering following the surface contours of the cardboard.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,235,401 describes a device of this type with which the material web to be coated is deflected onto a transfer roller from a guide roll of an applicator. The transfer roller drags spreadable dyestuff from a dyestuff bath [tray or trough] and entrains it in excess onto the web. To strip off a part of the spreadable dyestuff applied in excess, the web following the transfer roller is guided over a driven roll squeegee rod [roll doctor rod] provided with a wire wrapping. At a distance from the roll squeegee rod there follows a counter roller about which the web is deflected and whereby, in the looped region of the controllers, an air blade is arranged which strips the surplus spreadable colorant off to the desired coating weight.
It is a disadvantage of known air blade machines, especially with large machine widths, that a closed and uniform coating of the material web can only be produced at limited production speeds (less than 500 m/min).
OBJECT OF THE INVENTION
The invention has as its object to improve a coating device of the type described so that, without a reduction in quality, significantly higher production speeds can be achieved.
SUMMARY OF THE INVENTION
It has been found that, as a final metering device, with an air blade provided for this purpose, because of the over proportional increasing pulses of spreadable dyestuff with increasing web velocity, ever smaller amounts of the surplus can be removed. A condition for a minimal excess application is, however, a very uniform coating without local crowns, for example in the form of strips, which cannot be achieved at high speeds with the conventional coaters. In addition there are difficulties, for example dewatering of the applied spreadable dyestuff, with limited excess quantities, which affect the final metering with the air blade. This effect arises even by premetering upon the web, for example with a squeegee, or a so-called predosing roller.
According to the invention a uniform application is produced on the transfer roller with reduced excess prior to application to the web and which, because of the arrangement of guide roller, is transferred uniformly and in an error free manner to the web. Because of the reduced distance between applicator and air blade, the problems resulting from dewatering of the spreadable dyestuff at final metering are significantly reduced. The dependent claims contain preferred yet especially advantageous forms of the invention.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
FIG. 1 is a side elevation diagrammatic view of a coating device according to the invention; and
FIG. 2 is a sectional view of a squeegee bar wrapped with wire.
SPECIFIC DESCRIPTION
The material web 1 to be coated, a paper web or cardboard web, is deflected about a guide roller to pass tangentially along an upper part of a transfer roller 3 of an applicator 4. The rubber-coated transfer roller has a smooth peripheral surface. It is immersed with its lower part in a dye trough 5 into which the spreadable mass is fed in excess and in which a constant level is maintained by means of overflows or weirs 6 on both sides. The transfer roller 3 is rotated counter to the travel direction of the web 1, whereby the gap to the guide roll 2 amounts to less than 8 mm, preferably 0.5 to 3 mm. Through this limited gap, a laminar application of the web 1 onto
REFERENCES:
patent: 2679231 (1954-05-01), Pomper et al.
patent: 3235401 (1966-02-01), Fowells et al.
patent: 4848268 (1989-07-01), Sollinger et al.
Jagenberg Kunststoff-Beschichtungsanlagen; Jagenberg-Werke AG; Dusseldorf, No. 8174, Plastic Coating Installations, published Apr. 1957.
Franz Gunter
Sommer Herbert
Dubno Herbert
Jagenberg Aktiengesellschaft
Savage Matthew O.
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