PROCEDIMIENTO DE PREPARACION DE UNA HOJA FIBROSA, SEGUN TECNICAS PAPELERAS, PARA MEJORAR LA RETENCION Y EN PARTICULAR LA OPACIDAD

摘要

New method for the preparation of a fibrous sheet by using paper manufacturing techniques in order to improve the retention and particularly the opacity, said method being characterized in that 1) an aqueous suspension of fibrous is prepared; 2) an aqueous suspension of mineral filler and binder is prepared wherein the filler/binder mixture is preflocculated by means of a cationic flocculent; 3) at the head circuits of the paper machine and before the head box of the latter, the aqueous suspension of the preflocculated filler-binder mixture is introduced into the aqueous suspension of fibers so that (i) the average diameter of the flocks of the filler-binder mixture added into said fiber suspension is comprised between 0.01 and 0.3mm, and (ii) the contact duration of said filler-binder mixture with the fibers in the resultant suspension is comprised between 10 and 60 seconds; 4) before the heat box, a cationic flocculent is introduced into the aqueous suspension of the mixture of fibers-filler-binder obtained in the stage (3), so that the contact duration of said floculent with the mixture of fibers-filler-binder is shorter than 45 seconds; 5) the resulting aqueous suspension is introduced into the head box and forms a sheet on a paper machine which is pressed and dried.