Patent ID: 6630531
Filing Date: 2003-10-07
Classification: B32B,C08F,C08L,C09J,Y10T

Abstract:
A pressure sensitive adhesive having a rubber phase, said adhesive comprising:(a) 100 parts by weight of a polymodal asymmetric elastomeric block copolymer; (b) at least one midblock-compatible tackifier in an amount sufficient to raise the calculated Fox Tg of the rubber phase of said adhesive to greater than 245Â° K; (c) 0 to about 50 parts by weight of a crosslinking agent; and (d) 0 to about 300 parts by weight of a plasticizer; wherein said polymodal asymmetric elastomeric block copolymer has the formula QnY and comprises from about 4 to about 40 percent by weight of a polymerized monovinyl aromatic compound and from about 96 to about 60 percent by weight of polymerized conjugated diene, wherein: Q represents an individual arm of said block copolymer and has the formula Sâ€”B; n represents the number of arms Q in said block copolymer and is a whole number of at least 3; and Y is the residue of a multifunctional coupling agent; and further wherein: (a) S is a nonelastomeric polymer segment endblock of a polymerized monovinyl aromatic homopolymer, there being at least two different molecular weight endblocks in said copolymer, a higher molecular weight endblock and a lower molecular weight endblock, wherein: (i) the number average molecular weight of said higher molecular weight endblock (Mn)H is in the range of from about 5,000 to about 50,000; (ii) the number average molecular weight of said lower molecular weight endblock (Mn)L is in the range of from about 1,000 to about 10,000; and (iii) the ratio (Mn)H/(Mn)L is at least 1.25; and (b) B is an elastomeric polymer segment midblock which connects each arm to the residue of a multifunctional coupling agent (Y) and comprises a polymerized conjugated diene or combination of conjugated dienes, and wherein a film of said adhesive about 5 mils thick exhibits a 180Â° peel adhesion high density of at least 80 N/dm.