The basic components in the production of HMPUR are polyols and diisocyanates: by reacting them, they produce polyurethane prepolymer. The free isocyanate groups of this polyurethane prepolymer react with ambient moisture, once this latter is applied. During the production process of HMPUR, the addition of crystalline thermoplastic polyurethanes (TPUs) with different molecular weights and chemical structures (PEARLBOND?), allow the adhesives makers to adjust several properties such as green strength, setting-time, open-time, viscosity and specific adhesion to different substrates, depending on the application requirements. A formulation based on a mixture of crystalline and amorphous polyester has been used for the evaluation of the action of the crystalline TPUs (PEARLBOND?). Once the mixture is homogenized, the polyurethane prepolymer is formed by adding 4,4-diphenyl-methane diisocyanate (MDI).The influence of the addition of the different PEARLBOND? types on the final properties of the HMPUR is evaluated, as well as the proportions to be used.
展开▼
