Method for preparing modified fish-skin collagen sizing agent

The invention provides a method for preparing a modified fish-skin collagen sizing agent. The method comprises the following steps: cleaning saury skin, draining the saury skin, chopping the saury skin into small blocks, adding a NaOH solution, and carrying out stirring; carrying out cleaning and draining, then, adding n-butanol, and carrying out stirring; carrying out flushing, draining and enzymolysis; centrifuging an enzymolysis solution, concentrating supernatant, and carrying out drying, so as to obtain fish-skin collagen; crushing baked oil tea dregs, carrying out sieving, adding a mixedsolution of polyethylene glycol, ethylene glycol and propanetriol, phthalic anhydride and imidazole, carrying out a heating reaction, and carrying out filtering to remove filter residues, so as to obtain a reaction solution A; subjecting the fish-skin collagen, the reaction solution A, aluminum sulfate and distilled water to mixing and stirring; adding polyanionic cellulose, corn starch and dodecyl trimethyl ammonium chl