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 leastone midblock segment and at least one endblock segment. The midblock comprisesa polymerized conjugated diene segment or hydrogenatedderivative thereof. The endblock comprises a polymerized monovinyl aromaticsegment having a number average molecular weight lessthan about 8,000. The PSA further comprises at least one tackifier or oil thatis compatible with the low molecular weight endblock segmentof the block copolymer. The PSA composition of the invention has a reducedelastic index and is capable of dissipating stress. This isuseful in providing tapes which are capable of withstanding stresses such asthose caused by temperature fluctuations, dimensional changesin the backing, or the recovery forces of a backing applied under tension. Thepresent invention also provides a method of reducing theelastic index of a block copolymer PSA composition.