Coating apparatus – Immersion or work-confined pool type – Work-confined pool
Reexamination Certificate
1999-01-07
2001-05-22
Lamb, Brenda A. (Department: 1734)
Coating apparatus
Immersion or work-confined pool type
Work-confined pool
C118S302000, C118S419000
Reexamination Certificate
active
06235115
ABSTRACT:
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to coating applicators in general and to apparatus for applying coatings to moving substrates in particular.
Paper of specialized performance characteristics may be created by applying a thin layer of coating material to one or both sides of the paper. One type of coating fluid is a mixture of a fine plate-like mineral, typically clay or particulate calcium carbonate; coloring agents, typically titanium dioxide for a white sheet; and a binder which may be of the organic type or of a synthetic composition. Another type of fluid is a starch and water solution used in sizing applications. Coated paper is typically used in magazines, commercial catalogs and advertising inserts in newspapers. The coated paper may be formed with a smooth bright surface which improves the readability of the text and the quality of photographic reproductions. Coated papers are divided into a number of grades. The higher value grades, the so-called coated free-sheet, are formed of paper fibers wherein the lignin has been removed by digestion. Less expensive grades of coated paper contain ten percent or more ground-wood pulp which is less expensive than pulp formed by digestion.
Coated papers are often used for high-quality printing or in other applications where visible variations in coating weight would significantly detract from the appearance of the paper. It is therefore of key concern to maintain coating thickness consistency across the width of the treated web. Greater efficiency and cost control in papermaking has driven the construction of ever wider papermaking machines, sometimes of 300-400 inches or more. In conventional fountain applicators, a single supply chamber extends the full width of the web in the cross machine direction. This supply chamber may be fed from one or both ends. To minimize fall off of coating ejected from a nozzle which terminates the supply chamber, coating is supplied at a high pressure. Nevertheless, such coaters are prone to heavier coating application at the ends.
Furthermore, the heated coatings which are frequently employed can, over the extended cross machine width of the coater head, result in temperature gradients which cause bowing of the head with resultant coat weight variations.
What is needed is a papermaking fountain applicator which may be operated at lower pressures while still supplying consistent coating levels to the substrate in the cross machine direction.
SUMMARY OF THE INVENTION
The coating applicator of this invention has two coating supply tubes which extend parallel to one another and run the full width of the substrate in the cross machine direction. Coating is supplied separately to each supply tube from opposite ends. The supply tubes discharge coating through spaced metering holes into an application chamber defined between a sidewall mounted to each supply tube. The counterflow arrangement of the coating supply tubes results in the fall off of coating pressure in one tube being canceled out by the increased pressure in the other tube at any particular point moving across the coater head in the cross machine direction. The tendency of the pressure to fall as the coating moves through the supply tube may be further counteracted by varying the spacing between metering holes with cross machine position, by varying the diameter of the metering holes, or both.
The tendency of the heated coating to cause a temperature gradient in the applicator head may be counteracted by cantilevering the applicator head on arms from a support beam through which a temperature-controlling fluid is circulated.
It is a feature of the present invention to provide a coating applicator which supplies a coating to a jet applicator nozzle at a constant pressure.
It is another feature of the present invention to provide a coating applicator which is conveniently profile controlled.
It is an additional feature of the present invention to provide a papermaking coating applicator which is less susceptible to bowing due to temperature gradients.
It is also a feature of the present invention to provide a papermaking coating applicator which operates at reduced coating pressures.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3134126 (1964-05-01), Phillips
patent: 5199991 (1993-04-01), Chance
patent: 5269846 (1993-12-01), Eskelinen et al.
patent: 5480486 (1996-01-01), Burns
patent: 6053979 (2000-04-01), Bernert et al.
patent: 4432180 (1996-03-01), None
patent: 4432177 (1996-03-01), None
patent: 4432180A1 (1996-03-01), None
patent: 385301 (1990-02-01), None
patent: 0385301 (1990-09-01), None
patent: 514735 (1992-05-01), None
patent: 0514735A1 (1992-11-01), None
patent: 781608 (1997-07-01), None
patent: 0781608A2 (1997-07-01), None
patent: WO 96/07790 (1996-03-01), None
patent: WO 98/21408 (1998-05-01), None
European Search Report-EP99630010-Mar. 10, 2000.
“BA 1500™ Coater: Versatile, high speed blade applicator produces quality coated papers,” a brochure published by Rader Companies, a Division of Beloit Corporation.
“New Coating Technologies Combine High Speeds with Higher Quality,” an article publised in Pulp & Paper, by Andy Harrison, pp. 60-64, May 1994.
Bassett William J.
Goecks Roger L.
Beloit Technologies Inc.
Lamb Brenda A.
Lathrop & Clark LLP
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