METHOD OF PRODUCING SOLVENT-FREE TWO-COMPONENT POLYURETHANE ADHESIVE HAVING LOW CONTENT OF FREE DIPHENYLMETHANE DIISOCYANATE

摘要

A method of producing a solvent-free two-component polyurethane adhesive having low content of free diphenylmethane diisocyanate (MDI) monomer is provided. The method includes esterifying dihydric alcohol and diacid to obtain component A, reacting MDI monomer with polyol to obtain component B according to the mole ratio of NCO/OH=3~5.5:1. The production of component B includes dehydrating polyol until the water content (mass percent) is less than 0.05%, adding the MDI monomer and a molecular weight regulator, heating to the temperature of 70~80? until the hydroxyl groups in the reaction system are completely reacted; adding a trimerization-catalyst to proceed a trimerization reaction until the reaction is completed, then the reaction is finished and the component B is obtained. The method has simple process, low production cost. The polyurethane adhesive obtained has low content of free MDI monomer, fast curing speed, high solvent resistance and hydrolysis resistance. There is no solvent contained in the component A and component B of the solvent-free adhesive, which is environmental-friendly and energy-saving, and the adhesive has good storage stability and is favorable for transporting and applying.