OPTICAL BRIGHTENER FOR AQUEOUS HIGH YIELD PULP AND PROCESS FOR MAKING BRIGHTENED PAPER

摘要

Paper is brightened by addition of a tetrakis(hydroxyalkyl) phosphonium ("THP") salt in an amount greater than 0.04% but no more than 5% by weight i n wet pulp. The amount of THP salt added is sufficient to enhance the brightness o f paper made from fibers in the wood pulp to a desired brightness level. The THP sal t is commercially available and previously used as a fire retardant and a biocide . Though particularly useful in the production of brightened cellulose fibers of high yield pulp, with the benefit of generally improving opacity, the process may be used to treat all wet pulp which is to be brightened.