PRESSURE-SENSITIVE ADHESIVE COMPOSITION AND PRESSURE- SENSITIVE ADHESIVE ARTICLE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive composition containing a pressure- sensitive polymer obtained by polymerizing a monomer component essentially consisting of an alkyl (meth)acrylate by the use of a polymeric polymerization initiator having a specified structure while realizing an increase in the molecular weight of the polymer and reduction in low-molecular-weight products in the polymerization step, and improvement in both pressure-sensitive adhesiveness and cohesive force. SOLUTION: This composition contains a pressure-sensitive adhesive polymer obtained from a monomer component essentially consisting of an alkyl (meth)acrylate. The pressure-sensitive adhesive polymer is obtained by polymerizing the monomer component in the presence of such an amount of a polymeric polymerization initiator having a structure represented by formula I (wherein R1 is a divalent linear hydrocarbon group; and m is 3 or greater) and/or formula II (wherein R2 and R3 are each a linear or cyclic hydrocarbon group optionally containing an ethylene group on the chain; and n is 2 or greater) in the main chain as to give an active oxygen concentration of 5-300 ppm. The pressure-sensitive adhesive polymer is one having a weight- average molecular weight Mw of at least 200,000 and an Mw/Mn ratio of at most 6 (wherein Mn is the number-average molecular weight).