Adhesion Mechanism for Block Copolymer/Tackifier BlendAnalyzed Using Difference Spectrum Measured by Pulse NMR

Abstract

To investigate the adhesion mechanism of pressure-sensitive adhesive（ PSA） by the tackifier addition, thedifference spectrum was measured using 1H pulse nuclear magnetic resonance（ pulse NMR） for the blend ofacrylic triblock copolymer consisting of poly（methyl methacrylate）（ PMMA） block and poly（n-butyl acrylate）（PBA） block and special rosin ester tackifier（ RE）. The pulse NMR was measured for base polymer and REseparately. The combined spectrum was prepared by the addition of both signals based on the mixing ratio.The pulse NMR of the blend was measured as the measured spectrum. The difference spectrum was madeby the deduction of the combined spectrum from the measured spectrum. The three peaks based on RE, therelatively harder PBA and the relatively softer PBA were appeared. The height of them were dependent on theRE content and molecular weight. RE exists in the base polymer as the miscible state or as the agglomeratedparticles in PBA. These three peaks indicated that the degree of formation of the agglomerated particles andthe restriction of molecule mobility of PBA. The analysis for the styrenic block copolymer/tackifier systemwas also conducted by the same method. The result of difference spectrum was found to be useful for thediscussion of the adhesion properties.