Process for improving the Quality of Pulp Obtained from Wastepaper

摘要

The method removes a contaminant, such as adhesive particles, from wastepaper pulp. The method includes the steps of dispersing a particulate polymeric substance in the pulp containing the contaminant particles so as to form a mixture which is heated above the softening point of the polymeric substance whilst maintaining the dispersion. The contaminant particles adhere to the particles of the substance and the mixture is cooled below the glass transition temperature of the polymeric substance to enable them to be removed by screening. Polyvinyl acetate, poly-n-butyl methacrylate and poly-n-propyl methacrylate are suitable polymeric substances. Agitation may be controlled during the heating step to provide an optimum or desired removal of contaminant particles.