Comparison of morphological properties waste paper fibers from newspaper and office paper types

Abstract

The article presents comparative results of scientific studies of the structural and morphological properties of the waste paper stock after flotation with preliminary wet and dry pulping. Newsprint and printed office paper were used as waste paper. It is known that these types of waste paper differ significantly in quality and price, since the paper pulp obtained on their basis differs in paper-forming properties, which are mainly determined by the morphological characteristics of secondary fibers. The pulping of waste paper by the wet method was carried out in a disintegrator, dry pulping – in a rotary-vortex mill. Cleaning of the waste paper stock by flotation was carried out on a laboratory installation by a standard method. It was found that the dry pulping of newspaper waste paper before flotation, compared with wet, significantly reduces the average fiber length from 0.92 to 0.56, while the amount of small change increases by 2 times from 2.57 to 4.82%. Dry pulping of newspaper waste paper can be recommended in the manufacture of paper products by casting using binders. With dry pulping of office waste paper in comparison with wet does not lead to a decrease in the average length of the fiber, it is 0.96 mm. With dry pulping, the amount of the shortest fraction of the trifle increases to 76%, with wet 60%, the twisting of the fibers increases (7.3 with wet – 10.7 with dry dissolution). The curvature and twisting of the fibers leads to an increase in the thickness and a decrease in the density of paper, may lead to a decrease in mechanical performance, but an increase in absorbency, therefore, dry pulping of office waste paper before flotation can be recommended for the production of absorbent types of paper and cardboard.