Metso Paper Inc.

Valmet Paper Machinery Inc.

Jussi Tuomela

Harri Kuosa

Pekka Koivukunnas

Juhani Vestola

Pentti S Lehtonen

Mikko Tani

Kari Niemi

Juha Wahlroos

Markku Ellila

Jorma Majava

A roll for use in the manufacture of paper and board, a press roll, in particular a center roll in a press, a backup roll for an extended-nip press roll, a hot press roll, or equivalent, which is in direct contact with a wet paper web, or a calender roll, a method for manufacturing the same and a coating composition therefor including an adhesion layer arranged on the frame part of the roll and a ceramic layer arranged on the adhesion layer. The ceramic layer has a thickness of from about 100 &mgr;m to about 2000 &mgr;m and includes from about 50% to about 95% by weight of Cr O and from about 3% to about 50% by weight of TiO , or from about 50% to about 80% by weight of Al O and from about 20% to about 50% by weight of ZrO , or exclusively Al TiO . The outer face of the ceramic layer is finished until the roughness Ra is from about 0.2 &mgr;m to about 2.0 &mgr;m and/or the porosity of the outer face of the roll is from about 1% to about 20%. In addition to or instead of TiO , the ceramic layer may contain oxides of aluminum, silicon, zirconium, magnesium, manganese, tin, tungsten and mixtures thereof.

Method for manufacturing a paper or board machine and coating composition therefor

A paper web is passed through a calendering nip that is formed between a roll which has been provided with a soft face and a heatable hard roll. The heatable roll is heated so as to plasticize the surface layer of the paper web that is placed at the side of the heatable roll, preferably so that the temperature of the surface layer in the calendering nip exceeds the glass-transition temperatures of the polymers contained in the paper. Before entering into the calendering nip, the paper web is moistened, so as to lower the glass-transition temperatures of the polymers contained in the paper, and pre-heated. The pre-heating of the paper web is carried out by bringing the paper web into contact with the heatable roll before the web enters the calendering nip and by, before the calendering nip, feeding steam or water onto the face of the paper web that is placed at the side of the heatable roll so as to improve the transfer of heat from the hot roll to the paper web.

Method in calendering of a paper web and a calendar that makes use of

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Järvenp{umlaut over (aa)}, Finland

Jussi Tuomela