Method of preparing polyurethane hot melt adhesive with high temperature resistance

A method of preparing polyurethane hot melt adhesive having high temperature resistance, comprising the following steps:

• 1) adding 10-20 parts by weight of isocyanate with an average functionality of more than 2.5 to a reactor and maintaining an inert atmosphere, heating the reactor to a temperature of 60-80° C., then adding 0.3-3.0 parts by weight of silane modifier to the reactor, and stirring while maintaining a constant temperature of 60-80° C. for 1-3 hours to obtain isocyanate derivatives with an average functionality of 1.5-2.0 from a reaction, and then adding 0.005-0.04 parts by weight of chemical dehydrant into the reactor and mixing evenly;
• 2) adding 1-5 parts by weight of dehydrated diluent and 7-20 parts by weight of dehydrated tackifier resin to the reactor after the reaction in step 1), maintaining the inert atmosphere in the reactor, increasing a temperature of the reactor to 100-120° C., stirring for uniform mixing, followed by adding 25-45 parts by weight of dehydrated crystalline polyester polyol and 6-20 parts by weight of dehydrated polyether polyol, and reacting under stirring and the temperature of 100-120° C. for 0.5-2 hours;
• 3) adding 15-35 parts by weight of dehydrated polyether amine to the reactor after the reaction in step 2), maintaining the inert atmosphere in the reactor, and reacting under stirring and a temperature of 115-140° C. for 1-2 hours;
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• 4) adding 0.01-0.2 parts by weight of catalyst into the reactor after the reaction in step 3), vacuumizing to remove bubbles, discharging materials from the reactor and hermetically packaging the materials to obtain the polyurethane hot melt adhesive with high temperature resistance.