Study on the Effect of Urethane/Urea on the Adhesion Fastness of Polyester Polyurethane by Contact Angle
A series of polyester polyurethanes(PU)with different molar ratios of urethane/urea were synthesized by using polyester diol XCP-2000PM(PM)as the soft segment.The influence of urethane/urea on the surface energy of polyester polyurethane film and the adhesion work between bioriented stretching polyester film(BOPET)and PU were studied by contact angle test.The influence of urethane/urea molar ratio on adhesion fastness before and after boiling was studied when by bonded with BOPET,and its heat resistance was also studied.The results showed that with the change of urethane/urea,the overall changes of surface energy and adhesion work were small.The surface energy was mainly nonpolar Lifshitz-Vander WaalsγLW,and the adhesion work was mainly nonpolar work WLWBi.The acid-base contribution of the two was small,but PU-P1 and PU-N1 showed relatively strong acidic effect.There were some differences between the actually tested adhesion fastness and the theoretical surface energy and adhesion work.When the urethane/urea was 10/90,the adhesion work of PU-P1 and PU-N1 were relatively low,and the actual adhesion fastness was elatively good due to the acid-base effect in the surface energy and better wettability and spreadability;The adhesion work of PU-B1 was the largest,and its actual adhesion fastness was the smallest due to its larger apparent viscosity.When the urethane/urea was 40/60,the adhesion fastness were relatively best,which were consistent with the theoretical adhesion work and surface energy.After the coating samples were boiled for 30 min,the adhesion fastness decreased to a certain extent,while PU-N and PU-E could maintain good adhesion fastness,while PU-B decreased significantly.With the increase of urethane/urea,the initial thermal decomposition temperature T5％and Tmax of polyurethane generally showed a downward trend,and the T5％of PU-B was the highest,while the T5％of PU-P was the lowest.
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