Use of Pigments to Produce High Quality Msp Coatings, 1996 Metered Size Press Forum Proceedings

P.G. Drage & A.G. Hiorns

English China Clays plc

St. Austell

The quality of paper coated using a metered size press depends critically upon the correct choice of pigment. Pigment must be chosen not only for its influence on paper and print properties (sheet and print gloss, brightness, smoothness etc.) but also for its runnability on the metered size press; an incorrect choice will lead to, for example, film split problems which will result in an undesirable orange peel mottle on the coated sheet. This paper presents results for coated woodcontaining and freesheet grades illustrating the effect on paper and print performance of varying the pigment or blend ratio in pigment mixes. In the applications studied, provided that acceptable film split and film transfer could be achieved, pigments generally show the same trends as in blade coating i.e. GCCs give high brightness but low gloss, fine U.S.-sourced hydrous clays give high paper gloss and U.K.-sourced hydrous clays give high delta gloss (snap) after printing.