Patent ID: 8318852

Claim:
An acrylic pressure sensitive adhesive composition for a polarizing film comprising: a high molecular weight acrylic polymer for crosslinking structure; a high molecular weight acrylic polymer for non-crosslinking structure; a low molecular weight acrylic polymer; and a multi-functional crosslinking agent, wherein an acrylic pressure sensitive adhesive made from the composition has a gel fraction represented by the following formula (1) of 10 to 55%, wherein the acrylic pressure sensitive adhesive has a swelling ratio represented by the following formula (2) of 30 to 110, wherein the weight average molecular weight of a sol is at least 800,000, the sol being eluted from the acrylic pressure sensitive adhesive, wherein the sol comprises 10 to 40 wt % of a low molecular weight material having the molecular weight of not more than 100,000, wherein the high molecular weight acrylic polymer for crosslinking structure has a weight average molecular weight of 1,000,000 to 2,500,000, wherein the high molecular weight acrylic polymer for non-crosslinking structure has a weight average molecular weight of 1,000,000 to 2,500,000, wherein the low molecular weight acrylic polymer has a weight average molecular weight of 3,000 to 100,000, wherein gel fraction (%)= B/A ×100 (1), wherein swelling ratio= C/B (2), wherein A represents the weight of the acrylic pressure sensitive adhesive, B represents the dry weight of insoluble content in the acrylic pressure sensitive adhesive after dipping it in ethyl acetate at ambient temperature for 48 hours, and C represents the weight of insoluble content swelled by ethyl acetate after dipping it in ethyl acetate at ambient temperature for 48 hours.