Influence of water system closure on strength properties of packaging papers

Handsheets of paper were made to simulate the manufacture of testliner and fluting (corrugating medium) in a recycled paper mill having various levels of water-system closure. The handsheets were made using water taken from a recycled paper mill having a totally closed water system, diluted with fresh water to various degrees. Several levels of starch addition and temperature were used in the experiments. It was found that the beneficial effect of starch on dry strength decreased to zero as the proportion of recycled water increased. Possible reasons for this effect are discussed. Also discussed are the implications for manufacturers of packaging papers of the trend towards zero liquid effluent in papermaking.