RUNNABILITY ASPECTS IN HIGH-SPEED FILM TRANSFER COATING

A runnability study tried to determine, eliminate and explain the caus es of coating color misting in a film transfer process at 1200-2000 m/ min. The work examined one-side film transfer with clay and calcium ca rbonate pigments at two solids contents. Dewatering and penetration of the premetered coating film into the paper followed by coating film s plit at the nip outlet influence the transfer process in the nip. A tr ouble-free transfer process requires reduced water holding properties or higher solids content of the coating color to compensate for the sh orter contact time in the transfer nip at higher machine speeds. Witho ut such optimization of the coating color, runnability problems such a s misting of the coating color will occur at increased speed.