RECYCLYING OF WET STRENGTH PAPERS

Abstract

Fibers in a sheet of paper are bonded with each other through hydrogen bond. These hydrogen bonds are formed at the time of drying of sheet & these bonds can be easily broken upon wetting & consequently disintegrating the sheet. This bond formation & bond breaking allows paper to be recycled. The wet strength papers are special grade of paper that do not disintegrate easily upon wetting & retain more than 15% of the tensile strength of the dry paper even with paper is completely saturated with water. The wet strength papers are therefore not easy to repulp & reuse for paper making. Many Indian paper mills using imported wet strength waste paper particularly Kraft carrier board (KCB) , experience great difficulty in its use they sometimes have to cooked the waste paper with water at temperature as high as 140 °C involving a high operating cost & negative environmental impact. In the present study many different ways of repulping wet strength waste paper have been studied with regard to pulping time, the strength properties of recovered pulp & the environmental impact of the process.