| Summary: | The objective of this research was to investigate the interaction of tackifier resins in water-based and olefinic polymers for potential pressure sensitive adhesive applications. The first part of this research work was focused on evaluating the usefulness of olefinic block copolymer blends with two amorphous polyolefins (atactic propylene homopolymer and ethylene-propylene copolymer) as potential base polymers for hotmelt pressure-sensitive adhesives. Unsaturated and saturated hydrocarbon resins were studied as potential compatibilizing agents and rheology modifiers. Results show that the chemistry of hydrocarbon resins definitely influence the miscibility of the olefinic block polymer and amorphous polyolefin blends. Ethylene-propylene amorphous copolymer based blends seems to show better miscibility characteristics. Based on the learning from blend miscibility studies, we have successfully made pressure-sensitive adhesives for disposable diaper construction application with olefinic block copolymer/ethylene-propylene amorphous copolymer blends, containing unsaturated hydrocarbon resins and saturated hydrocarbon resins. These olefinic adhesives showed good sprayability characteristics, when applied using air assisted spiral spray equipment (Acumeter Spray Coater) and they showed good adhesive peel properties, which were comparable to the SBS based control. The second part of the study was focused on the evaluation of natural rubber latex-based pressure-sensitive adhesives (PSA) containing three different C5 aliphatic tackifier dispersions with different softening points. Natural rubber-based, water-borne PSA wet rheology (rheology in liquid state) was correlated to morphological analysis on a coating and converting stand point. Dry adhesive rheology was also studied and was then correlated to adhesive properties at different conditions. It has been learned that the type and amount of dispersing agents in tackifier dispersions has a major influence in wet rheology of the PSA formulations. Softening point of the dispersion seems to influence the dry adhesive rheology and adhesive properties such as peel, tack and shear.
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