Valmet Corporation

Mika Leino

Stefan Kuni

Jukka Linnonmaa

Erja Nikula

Stig Renvall

Petri Paloviita

Jaana Ahlroos

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

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Järvenp{umlaut over (aa)}, Finland

Mika Leino