Preparation method of thermocuring polyurethane pressure-sensitive adhesive

The invention discloses a preparation method of a thermocuring polyurethane pressure-sensitive adhesive, which comprises the following steps: reacting isocyanate, polyol and a chain extender to generate a prepolymer, adding a sealing agent to obtain a sealed prepolymer, and heating and pressing to cure with the polyol, and specifically comprises the following steps: S1, under the protection of nitrogen, adding a catalyst to obtain a prepolymer; the preparation method comprises the following steps: adding 50-70 parts by weight of polyol, 3-6 parts by weight of a chain extender and 15-25 parts by weight of isocyanate into a reaction kettle, carrying out reduced pressure distillation dehydration at 80-85 DEG C for 40-60 minutes, cooling to 50-60 DEG C, and reacting for 3-5 hours to obtain a PU prepolymer; s2, reducing the temperature in the step S1 to 38-45 DEG C, adding a sealing agent, stirring, and reacting for 25-35 minutes to obtain a sealed PU prepolymer; and S3, mixing the product obtained in S2 with poly