Pressure sensitive adhesive comprising a block copolymer having low molecular weight endblocks and endblock-compatible tackifier or oil

摘要

The present invention provides a block copolymer pressure sensitive adhesive (PSA) composition. The block copolymer has at least one midblock segment and at least one endblock segment. The midblock comprises a polymerized conjugated diene segment or hydrogenated derivative thereof. The endblock comprises a polymerized monovinyl aromatic segment having a number average molecular weight less than about 8,000. The PSA further comprises at least one tackifier or oil that is compatible with the low molecular weight endblock segment of the block copolymer. The PSA composition of the invention has a reduced elastic index and is capable of dissipating stress. This is useful in providing tapes which are capable of withstanding stresses such as those caused by temperature fluctuations, dimensional changes in the backing, or the recovery forces of a backing applied under tension. The present invention also provides a method of reducing the elastic index of a block copolymer PSA composition.