Pressure-sensitive adhesive composition

Claim 1

A pressure-sensitive adhesive composition consisting essentially of a tackifier selected from the group consisting of: (i) an isoprene-piperylene copolymer having a Ring and Ball softening point of about 10° to about 135° C., a molecular weight of about 400 to about 3000 and a weight ratio of isoprene to piperylene of about 1:10 to about 10:1; (ii) a piperylene/2-methyl-2-butene copolymer having a Ring and Ball softening point of about 10° to about 135° C., a molecular weight of about 400 to about 3000 and a weight ratio of piperylene to 2-methyl-2-butene of about 1:10 to about 10:1; (iii) beta terpene resins having a Ring and Ball softening point of about 10° to about 135° C. and a molecular weight of about 300 to about 3000; and (iiii) rosin or rosin esters having a Ring and Ball softening point of about 10° to about 190° C. and a molecular weight of about 300 to about 3000; in combination with an elastomer comprising isoprene and piperylene having a molecular weight of at least about 40,000; and a solvent; said elastomer having been prepared by a process for preparing an elastomer comprising copolymerized C 5 -hydrocarbons prepared from a hydrocarbon mixture containing C 5 -monoolefinic hydrocarbons, C 5 -diolefinic hydrocarbons, C 5 -paraffins, C 6 -paraffins and benzene, which comprises (A) heat-soaking said hydrocarbon mixture at a temperature sufficient to dimerize cyclopentadiene; (B) separating the resulting hydrocarbon mixture from the cyclopentadiene dimer; and (C) copolymerizing the resulting hydrocarbon mixture in the presence of a catalyst which comprises an iron complex, a trialkyl aluminum and a bidentate ligand capable of both pi and sigma bonding, the weight percents of the three components being 5-35 elastomer, 5-35 tackifier, and 30-90 solvent.