DEVICE FOR LEVELLING AND ESTABLISHING THE THICKNESS OF A LIQUID AGENT LAYER APPLIED TO MATERIAL

Description

[0001] The subject of the invention is a device for levelling and establishing the thickness of a liquid agent layer applied to a web of moving coated or lacquered material. This solution relates in particular to levelling and establishing the thickness of a layer of lacquer or impregnating agent applied to pre-impregnated decorative paper or to film base. The device may also be used for coating other papers, films and materials.

[0002] The known devices for the implementation of this goal consist of: a module applying a liquid agent to a web of moving material, comprising, inter alia, applying elements and rollers, a module pulling the web with the applied layer of the liquid agent, ensuring relative movement between the material and the module applying the liquid agent with the use of a system of rollers, and a blade placed behind the module applying the agent in the direction of movement of the material, ensuring a resistance of the flow and wiping off the excess of the agent from the material in such a manner as to ensure a layer with a defined surface and thickness.

[0003] From US 4076864 entitled "Method and apparatus for coating both sides of a moving web" a method and an apparatus are known in which the web is fed longitudinally at a speed in excess of 300 meters per minute, between a rotating support roller and a blade, the blade having a bevel at the point of contact with the web. Coating material is fed into the nip between the roller and the web to coat the paper web on both faces. An important element of this invention is a flexible blade that surrenders to the thrust of the liquid.

[0004] The Meyer Bar method is commonly known. In a device for the implementation of this method the module applying a liquid agent comprises, inter alia, a roll applying a liquid agent to the material, called an applicator roll and a tank with a liquid agent. Blades are used for wiping off the excess of a liquid agent and controlling both its quantity and thickness of the coat and they are in the form of steel round rotary rods made of stainless steel, wound tightly with nickel-chromium steel wire of varying diameter. The wet layer thickness after scraping depends on the diameter of the wire used to wind the roller and is approximately 0.1 times the wire diameter. The dry layer thickness of the applied agent depends on the solids concentration of the coating agents. The module pulling the web with the applied layer of a liquid agent in the Meyer Bar method consists of multiple drive rollers for guiding, pulling and supporting and distributing the web of material to subsequent modules of the device. In the device for using this method the blade is mounted on a supporting cradle and placed in the space between the applicator roll of the module for applying the liquid agent from the tank to the material and the pulling roll which is an element of the pulling module of the device, located on the opposite side of the blade in relation to the applicator roll. The disadvantages of the Meyer Bar method are considered to include the limited evenness of the applied agent, low speed of its application, sensitivity to the aquaplaning phenomenon at higher speeds and lack of elimination of defects of the base material.

[0005] The second known method, the so-called blade chamber, consists in applying lacquer to material using an applying screen roll, to which a blade chamber is pressed and to which the applied agent is fed under pressure. The applying screen roll with ink carriers, placed on its surface and filled with the applied agent, rotates in a direction reverse to a travel direction of the material web. The material is placed against the screen roll by a press roller at a specific distance, but without pressure, and the applied agent is rubbed into the coated material. In the device for implementing this method the module applying a liquid agent comprises: a Blade chamber, a screen roll and a press roller (positioning roller), and the module pulling the web with the applied layer of a liquid agent consists of at least a drive roller and guide rollers. In the device for this method the blades are knife-shaped and form the edges of the pressure chamber. After pressing the screen roll they form a hermetic dosing system. The disadvantages of this method include relatively difficult and complicated operations related to the retooling, part replacement and maintenance of the device, sensitivity to contamination and lack of sufficient elimination of defects of the base material.

[0006] Moreover, from US5741550 entitled "Blade metering unit and method for blade-coating a material web" a method and an apparatus are known for applying a coat mix to a high-speed running board or paper web by accurately premetering and pre-smoothing the applied coat with an applicator apparatus and then minimally doctoring the applied coat with an air knife. The method is based on applying a layer of coating mix of precise thickness to the web by means of a narrow slot-orifice applicator operating with a counterflow in the reverse direction to the web travel and having precise control of the mass flow of the coat mix (liquid agent) applied to the web so as to achieve a desired coat weight. The apparatus in this case does not have a roll applying a liquid agent from the tank, but an applicator module with a narrow orifice-slot extending in a cross-machine direction for facilitating high-speed laminar flow of coating mix into a gap region defined by confronting surfaces of the applicator apparatus and the web. The applicator apparatus has a member for directing the ejected coating mix in the gap region in a direction reverse to a travel direction of the web so that only a predetermined portion of the ejected coating mix is allowed to form an applied coat on the web. This accurate premetering of the coating mix by the applicator apparatus permits an operator to readily optimize the subsequent process of doctoring the applied coating with an air knife. This method requires very complicated equipment and high process precision as well as the use of multiple control and regulation devices ensuring the maintaining of extremely high operating parameters.

[0007] The goal of the invention is the creation of a device enabling the maximum elimination of defects and unevenness of the created coat, related to the teleportation of defects and contamination of the rolls guiding the web and rolls cooperating with the blade, the ensuring the self-cleaning of the blade, the elimination of negative effects of aquaplaning and the use of this phenomenon as a method for establishing an even thickness of the applied coat.

[0008] A device for levelling and establishing the thickness of a liquid agent layer applied to coated or lacquered material according to claim 1 is provided. Advantageously, the angle of positioning of the knife is within a range of 5°to 80°. Advantageously, the width of the working area of the knife blade is within a range of 0.01mm to 15 mm.

[0009] The subject of the invention is presented in its embodiment in the drawings where Fig. 1 shows a schematic view of the device. Fig. 2 presents the positioning of the knife against the material web, with the following marked: a liquid agent layer and a zone of increased hydrodynamic pressure, as well as a schematic run of scraping of the excess lacquer. The device in the embodiment is designed to apply lacquer in a lacquering machine. The material in the form of a preimpregnated foil web 1 is moved with a system of pulling, supporting and guiding rollers, located both in the part which forms the module pulling the web and the applicator module of the lacquering machine. Between the applicator roll 2 of the lacquer applicator module and the pulling roller 3 of the module pulling the web 1 a blade in the form of a knife 4 is located. It is located directly next to the pulling roller 3, however outside the space of wrapping of this roller by the web. The applicator roll 2 is placed above the lacquering tank 5 with lacquer 6, located directly under the material web 1. Moreover, both the pulling module and the applicator module are equipped with additional guiding and supporting rollers. The knife 4 is mounted on the adjustment mechanism 7 enabling the change of its positioning against the material web (up-down; front-rear; and angle of inclination). The material web with a width of 2540 mm travels with a speed of 280 m/min. through the following elements of the lacquering machine: unwinding machine, pulling in station, lacquering module, guiding and pulling rollers, dryer, pulling out station and rewinding machine.

[0010] The knife is set using the adjustment device 7 at an angle α = 45° in relation to the material web.

[0011] The device uses the linear placement of the knife against the moving, appropriately tensioned and coated material, which by creating a zone of increased hydrodynamic pressure 8 and specific stable surface hydrodynamic overpressure of the liquid material (aquaplaning) applies the lacquer evenly to the entire surface.

[0012] The adjustment of the angle α of positioning of the knife in relation to the web surface, combined with appropriately selected parameters: speed of web travel, web tension and quantity of lacquer allow obtaining self-cleaning of the knife blade. Devices for controlling web tension and tool pressure are widely known and used as standard in the printing and paper industry. During the process, as a result of rapid travel of the material web already coated with a liquid agent, in the zone where the knife 4 is placed against the material web an increased hydrodynamic pressure zone 8 is formed, in the form of a "wedge", which results in the loss of direct contact of the scraping knife blade 4 with the coated material web 1. As a result of the creation of hydrodynamic pressure, a phenomenon of so-called aquaplaning occurs, which causes the forming of a continuous layer of the coated material, with full control over the thickness and quality of the layer.

[0013] In the embodiment the following were used: material web travel speed - 280 m/min; material web tension for its full width - 850 N; viscosity of the applied agent - 16 seconds (measurement with a Ford cup DIN - 4 mm DIN 53211); knife positioning at an angle of α = 45° in relation to the material web; knife with a working area width (D) = 0.25 mm. As a result of using the invention a high-quality product is obtained with high uniformity of the coated surface, the number of so-called weak points of the material are reduced, self-cleaning of the knife blade, i.e. getting rid of particles of hardened lacquer or lacquer contaminations, is ensured.

Claims

1. A device for levelling and establishing the thickness of a liquid agent layer applied to coated or lacquered material, consisting of a module applying the liquid agent to a moving web (1) of the material, a module pulling the material web and at least one blade wiping off the excess of the liquid agent, positioned at the coated side of the material web, wherein the blade has the form of a knife (4), and wherein the knife blade (4) is connected with a device (7) for adjusting the pressure of the working area of the knife blade (4) on the web (1), and thus the web (1) tension, and the angle (α) of positioning of the knife blade (4), characterized in that the knife blade (4) is mounted outside of the wrapping space of any roller (3) of the pulling module.

2. A device in accordance with claim 1, characterized in that the angle (α) of positioning of the knife blade (4) is within a range of 5° to 80°.

3. A device in accordance with claim 1, characterized in that the width (D) of the working area of the knife blade (4) is within a range of 0.01mm to 15 mm.

Ansprüche

1. Eine Vorrichtung zum Ausgleichen und Bestimmen der Dicke einer auf einem beschichteten oder lackierten Material aufgetragenen Flüssigkeitsschicht, bestehend aus einem Modul zum Auftragen der Flüssigkeit auf ein laufendes Materialband (1), einem Modul zum Ziehen des Materialbandes und mindestens einem Abstreifer zur Entfernung von überschüssiger Flüssigkeit auf der beschichteten Seite des Materialbandes, wobei der Abstreifer die Form eines Messers hat (4) und wobei die Messerklinge (4) mit einer Vorrichtung (7) zur Anpassung des Drucks des Arbeitsbereichs der Messerklinge (4) auf das Band (1), und somit die Spannung des Bandes(1), und des Einstellungswinkel (α) der Messerklinge (4) verbunden ist, dadurch gekennzeichnet, dass die Messerklinge (4) außerhalb des Wickelbereichs der Rollen (3) des Zugmoduls angebracht ist.

2. Eine Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass der Einstellungswinkel (α) der Messerklinge (4) im Bereich von 5° bis 80° liegt.

3. Eine Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Breite (D) des Arbeitsbereichs der Messerklinge (4) im Bereich von 0,01 mm bis 15 mm liegt.

Revendications

1. Un dispositif pour niveler et établir l'épaisseur d'une couche d'agent liquide appliquée sur un matériau revêtu ou laqué, consistant en un module appliquant l'agent liquide sur une bande mobile (1) du matériau, un module tirant la bande du matériau et au moins une lame essuyant l'excès d'agent liquide, positionnée sur le côté revêtu de la bande du matériau, dans lequel la lame a la forme d'un couteau (4) et dans lequel la lame de couteau (4) est reliée à un dispositif (7) pour régler la pression de la zone de travail de la lame de couteau (4) sur la bande (1), et donc la tension de la bande (1), et l'angle (α) de positionnement de la lame de couteau (4), caractérisé en ce que la lame de couteau (4) est montée à l'extérieur de l'espace d'enroulement de tout rouleau (3) du module tirant.

2. Un dispositif selon la revendication 1, caractérisé en ce que l'angle (α) de positionnement de la lame de couteau (4) est compris entre 5° et 80°.

3. Un dispositif selon la revendication 1, caractérisé en ce que la largeur (D) de la zone de travail de la lame de couteau (4) est comprise entre 0,01 et 15 mm.

Drawing