Electron Microscopic Studies of Surface Fine Structures of Papers

Part 1. Effects of Various Coating Conditions on Fine Structures of Coated Surfaces

Abstract

The transmission and scanning electron microscopic studies were carried out as to the effects of various coating conditions on the surface fine structures of coated papers.
In comparing various replica techniques, the modified direct carbon replica method was found to be most available for observing the latex particles migrated to the coated surfaces.
Scanning electron micrographs revealed many holes and crevices in the coated surfaces which were hardly recognized by transmission electron micrographs.
Results were summerized as follows :
(1) It was found that raised fibers above the surface decreased as the coating weight increased. Most of these fibers were covered with clay coatings even in lower coating weight.
(2) The effect of supercalendering was satisfactorily shown by scanning electron micrographs.
(3) It was found that surfaces of coated papers were covered with binder films in proportion to the amounts of binders.
(4) The degree of latex particles migration to the surface was found to be proportional to the drying temperature. These latex particles tended to form discontinuous films which covered pigment particles, when migration proceeded excessively.
It is assumed that these films shall prevent papers from water absorption during high speed offset printing process.