Valmet Corporation

Stefan Kuni

Mika Leino

Jukka Linnonmaa

Erja Nikula

Stig Renvall

Petri Paloviita

Jaana Ahlroos

Juhani Saari

A method and apparatus for coating a paper or a paper board web, comprising spreading coating mix having a solids content of 55-75% on the surface of the web with a nozzle applicator, levelling and metering the spread coating mix on the surface of the web by a doctor element capable of producing a high hydrodynamic force on the coating layer between the doctor element and the web, the doctor element being located downstream of the applicator so that the dwell time between the spreading of the coating mix to the metering is 72-2400 ms. The web speed is preferably 100-1000 m/s. A good smoothness and coverage is achieved by this method due to long dwell time.

Method and apparatus for coating paper board and paper with high- viscosity coating mixes

A method and apparatus for producing paperboard, the method comprising the steps of applying a coating mix layer having a thickness greater than that of the final coat thickness to the surface of the web being coated using a coating mix formulation in which the solids content is at least 55%, passing the web with the coat applied thereto to a doctor blade located downstream in the travel direction of the web at a distance from the applicator apparatus such that the dwell time from the application step of the coating mix to the doctoring step is at least 130 ms, and smoothing the coat layer to its final thickness by means of a doctor blade. By this method a smooth surface can be obtained even on high coat weights.

Method and an apparatus for coating paperboard with a coating mix having a high solids content

Method and apparatus for coating a moving paperboard web with at least two coating layers. A first coating layer is applied onto the surface of the web and a second coating layer is applied onto the surface of this first undried coating layer. The first coating layer is applied by means of a film transfer coater and the second coating layer is applied by means of a nozzle applicator, whereby the first layer is neither mixed nor doctored off the web during the application of the second layer.

Method and apparatus for coating a moving paperboard web

An arrangement and method for calendering a board web including a calender providing a hot and hard calendering nip formed by two calender rolls and through which the board web passes. At least one of the calender rolls is arranged to be heated to such a temperature that the surface layer of the board web placed at the side of this roll reaches its vitrification temperature in the calendering nip. A film press is arranged directly before the calendering nip in the direction of transfer of the board web and includes a film press nip through which the board web is passed. The film press nip is arranged to transfer a liquid layer onto the face of the board web so as to moisten the board web. The board web is transferred from the film press nip into the calendering nip while the surface layer of the web is at the moisture level determined by the film press in view of producing a controlled moisture gradient.

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Järvenp{umlaut over (aa)}, Finland

Stefan Kuni