AAS1501 sizing agent is a fiber reactive sizing agent newly developed by our company for papermaking under medium alkaline conditions. It is a perfect replacement of the neutral sizing agent commonly used in the market at present. Its reaction mechanism is: AAS lotion particles are fixed on the fiber surface by means of cationic starch, polyacrylamide and other units or dual retention systems, During drying and storage, the hydroxyl groups of AAS molecules on cellulose molecules are esterified to complete the sizing process. Compared with the commonly used neutral sizing agent, ASS sizing agent has better curing rate, shorter curing time, and reduces the false sizing phenomenon caused by environmental factors.