Proposal of a Spray Type Agent for Interlaminar Strength Improvement

Abstract

In recent years, due to increasing electrical conductivity and the amount of anionic trash in paper making system, internal paper strengthen agent cannot show desirable performance. Therefore, spray type paper strengthen agent is required in which the agent will be applied just after wet sheet is formed. In multilayer papers, spray type paper strengthen agents are commonly used to obtain interlaminar strength. It is very common that non-gelatinized starch or chemically modified starch is sprayed in a slurry state between sheet layers. However, due to suction after papering and water squeezing in the pressing part, the spray-added starch moves from the interlayer to the inside of the layer together with water, and a part of the starch flows out of the paper. It is therefore, not possible to obtain good enough interlaminar strength, and starch flows into wastewater, which leads to deterioration of waste water load（COD, BOD）．

As a solution to these problems, it is conceivable to ⑴ switch traditional starch to PAM type paper strength agent for spraying, and ⑵ improve sprayed starch retention in between layers. In this report, these two process has been described.