Patent ID: 8895653

Claim:
An acrylic pressure-sensitive adhesive composition comprising: (A) a copolymer of butyl acrylate and acrylic acid; (B) an organophilic layered double hydroxide organically treated with an organic anion; and (C) a crosslinking agent, wherein the layered double hydroxide to be organically treated to provide the component (B) is a non-stoichiometric compound represented by one of the following general formula (1) and (2): [M 2+ 1-x M 3+ x (OH) 2 ] x+ [A n− x/n .m H 2 O] x− (1) [Li + 1-x M 3+ x (OH) 2 ] (2x−1)+ [A n− (2x-1)/n .m H 2 O] (2x−1)− (2) wherein M 2+ is a metal ion of at least one divalent metal selected from the group consisting of Mg, Ca, Mn, Fe, Co, Ni, Cu and Zn; M 3+ is a metal ion of at least one trivalent metal selected from the group consisting of Al, Fe, Cr, Mn, Co, Ni, La and Ga; A n− is an n-valent inorganic anion selected from the group consisting of OH − , ClO 3 − , ClO 4 − , F − , Cl − , Br − , I − , CO 3 2− , NO 3 − and SO 4 2− ; x is a positive number with 0<x<0.5; m is a positive number with 0<m; and n is a valence of the inorganic anion, wherein the component (B) is present in a proportion of from 3 parts by weight to 5 parts by weight based on 100 parts by weight of the component (A), wherein the component (C) is present in a proportion of from 0.1 to 3 parts by weight based on 100 parts by weight of the component (A), and wherein an adhesive strength of the acrylic pressure sensitive adhesive at 23° C. is from 3.5 to 6.8 N/20 mm.