Starch adhesive agent and preparation method thereof

The invention discloses a starch adhesive and a preparation method thereof. The starch adhesive is primarily prepared with 100 portions of starch, 350 to 450 portions of water, 50 to 100 portions of acroleic acid and 0.01 to 0.1 portion of lauryl mercaptan through radiation grafting polymerization. The preparation method comprises the following steps: the starch is added to a reactor; water is added to the starch and is uniformly stirred; subsequently, the acroleic acid and the lauryl mercaptan are added; the mixture is heated to be 60 to 85 DEG C so that the starch is gelatinized; subsequently, the mixture is arranged in a Co-Gamma ray radiation field for irradiation grafting polymerization with the received dosage of 0.2 to 2KGy; after the polymerization, sodium benzoate, sodium borate and bentonite are added and are stirred uniformly. The starch adhesive has the advantages of small product density, great cohesive force, no free alkali, quickly drying, low cost, high storage stability, long flatting and sto