To improve the straining properties and the yield of the loading material as well as increase the strength properties in the paper-making system in which a diluted polyacrylamide polymer solution is mixed with an aqueous solution of an aluminum compound and the mixture is added to the pulp slurry. ポリアクリルアミド系ポリマーの希釈液とアルミニウム化合物の水溶液とを混合してパルプスラリーに添加する抄造系において濾水性や填料歩留りを改善し、更に強度特性も向上させる。 - 特許庁