Patent ID: 8664326
Filing Date: 2014-03-04
Classification: C08L,C09J,Y10T

Abstract:
1. An acrylic pressure sensitive adhesive composition comprising: acrylic polymers including an alkyl(meth)acrylic acid ester monomer having 2 to 14 carbon atoms of an alkyl group, and a multifunctional crosslinking agent, wherein the acrylic polymers comprise an acrylic polymer for crosslinking structure that includes an alkyl(meth)acrylic acid ester monomer having 2 to 14 carbon atoms of an alkyl group and vinyl and/or acrylic crosslinkable monomer having carboxylic group or hydroxyl group crosslinkable with the multifunctional crosslinking agent, and an acrylic polymer for non-crosslinking structure that includes an alkyl(meth)acrylic acid ester monomer having 2 to 14 carbon atoms of an alkyl group and has no crosslinkable functional group, the acrylic polymer for non-crosslinking structure having a molecular weight greater than 300,000 wherein, the acrylic polymer for crosslinking structure, the acrylic polymer for non-crosslinking structure and the multifunctional crosslinking agent are comprised such that they can form a crosslinked product of the acrylic pressure sensitive adhesive composition by a crosslinking reaction of the acrylic polymers and the multifunctional crosslinking agent, wherein the crosslinked product has a gel fraction represented by the following formula (1) in a range of from 45 to 75%, and a swelling ratio represented by the following formula (2) in a range of from 5 to 20, and wherein the crosslinked product comprises sol that can be eluted from the crosslinked product by ethyl acetate and said sol has a weight average molecular weight of at least 300,000: wherein A represents the weight of the crosslinked product, B represents the dry weight of insoluble content after immersing the crosslinked product in ethyl acetate at ambient temperature for 48 hours, and C represents the sum of the weight of the insoluble content and the weight of solvent permeated into the insoluble content.