US 4,396,648 AGranted

Paper coating apparatus and method

AssigneeConsolidated Papers, Inc.

InventorsSherwood G. Holt, George H. Rasmussen

Life of this patent

Estimating the term…

Loading patent…

Abstract

Applicators for applying a film of coating material on a moving web of paper carried through an application zone include a chamber which receives coating material under pressure and directs the material through a narrow outlet orifice into the application zone, and a doctor blade which extends from a trailing side of the zone in contact with the web. The upper edge of a front wall of the chamber is closely spaced from the web to form, in conjunction with the pressurized coating material flowing from the orifice, a liquid seal at a forward end of the application zone, and seals are established at opposite side ends of the zone to allow development of a positive liquid pressure in the zone. In the various embodiments, rotating rolls located in the chamber, in the orifice, in the space between the upper edge of the front wall and the web and in both the space and the orifice serve to meter, homogenize and control the pressure of coating material in the application zone.

Claims12

Dependent claims

An improved method of applying coating liquid to a moving web of paper, comprising the steps of applying coating liquid under pressure to one surface of a moving web of paper carried through an application zone having spaced front and rear edges and laterally spaced side edges;

forming and maintaining a reservoir of coating liquid under pressure on the web in the application zone by introducing coating liquid under pressure into a chamber having front and rear walls the upper ends of which define the front and rear edges of the zone and an opening to the zone, and flowing the coating liquid in the chamber through the opening and into the zone;
doctoring the coating liquid on the web at the rear edge of the zone;
maintaining the coating liquid in the application zone under pressure by substantially sealing the side edges of the zone and by establishing a liquid seal in an orifice defined between the web and the front edge of the zone which extends substantially laterally across the web;
and continuously flowing coating liquid under pressure into the application zone to substantially completely and continuously fill the orifice with coating liquid for forming the liquid seal and for sealing off the front edge of the zone, wherein the improvement comprises the step of metering and treating the coating liquid by flowing the coating liquid through a narrow gap defined between a portion of a surface of an elongate rotating roll extending substantially laterally across the web and at least one of a surface of a wall to interior of the chamber and the surface of the web at the orifice, thereby to expose the flow of coating liquid to the moving surface of the rotating roll in the gap to control or meter its flow rate and therefore to control the pressure of coating liquid in the application zone and to homogenize the coating liquid to improve its viscosity and therefore the quality of coating applied on the web.

1 more element

An improved apparatus for applying coating liquid under pressure to one surface of a moving web of paper carried through an application zone, wherein the apparatus is of the type comprising a chamber having front and rear walls, side edges and an outlet slot between said walls and edges opening into and extending substantially transversely across said application zone, said front wall including a front edge spaced from the web and defining therewith an orifice;

means for substantially sealing to the web side edges of said application zone and said side edges of said chamber;
a doctor blade at a rearward end of said application zone for metering and leveling coating liquid on the web, said application zone being defined between said front edge and said doctor blade;
and means for continuously delivering coating liquid under pressure to said chamber, through said outlet slot and into said application zone for causing coating liquid under pressure to substantially completely and continuously fill said application zone and said orifice to form a liquid seal at a forward end of said zone, said liquid seal extending substantially continuously across the width of the web and sealing off the forward end of said application zone for maintaining the pressure of the coating liquid in said zone, wherein the improvement comprises an elongate metering and treating roll;
means for rotatably mounting said roll downstream of the point of introduction of coating liquid into said chamber to define a narrow gap between a portion of a surface of said roll and at least one of a surface of a wall to interior of said chamber and the surface of the web at said orifice, said roll extending substantially laterally across the web;
and means for rotating said roll, so that coating liquid delivered to said chamber flows through said gap and is exposed to said surface portion of said rotating roll therein for being metered to control its flow rate and therefore the pressure of coating liquid in said application zone and for being treated to homogenize it and improve its viscosity.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/347,000Filed 8 Feb 1982
Granted: 2 Aug 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

D21H 23/40
By contacting paper with an excess of material, e.g. from a reservoir or in a manner necessitating removal of applied excess material from the…
D21H 5/0015
By bringing paper into contact with an excess of fluids, the paper carrying away only a part of the fluid material, e.g. by passing through…: only…
D21H
Pulp compositions

Family

No related US applications are recorded in the indexed filing history.

Timeline

Citations

Open elsewhere

Building an agent or pulling many patents? Use the API or MCP server instead of scraping pages. Get an API key