In the paper industry, various types of paper strength agents have been widely used in order to improve the runnability of machines and also to achieve higher quality of product paper.In recent years. the branched type of copolymers, one of paper strength agents, has become more popular since it performs better than conventional agents in drainage and paper strength efficiency. As papermakers have been more seriously facing the strong economic demand of cutting costs, it may be one of the solutions for them to make full use of their machines by speeding up the process. Also considering the public demand for earth friendly industries, it is also important for us to make efforts to recycle used paper. Under such circumstances, we feel strong interests how we could satisfy such demands achieving the highly effective performance of paper strength agents at the same time.We are reporting the evaluation of the effects of various types of paper strength agents regarding drainage, formation, and quality of paper under several different papermaking conditions.

Recently, domestic paper demand has declined due to global economic recession. So, Japanese paper producers made scrap-and-build plans to concentrate production on larger and more efficient machines, thus reducing costs and have proceeded with these plans to improve revenue and enhance their competitiveness. Under these difficult circumstances, polyacrylamide(PAM)based dry strength resins(DSRs)is one of the best solutions for maintaining productivity and quality of paper.In order to overcome these problems, we have conducted the study based on the results for several model experiments that fixations of DSRs are different for pulps and PCC, and flocculation of PCC is also different, depending on ionicity(density)and molecular weight of DSR. As a result, we have developed novel PAM based DSRs for papers filled highly with PCC, which show excellent dry paper strength and high retention without excess flocculation of PCC fillers.