| 摘要 |
A low viscosity hot melt acrylic pressure sensitive adhesive polymer is formed by bulk polymerization of at least one alkyl acrylate monomer containing from about 4 to 8 carbon atoms in the alkyl group and present in an amount of from about 60 to about 95 % by weight of the polymer, from 1 to about 10 % by weight of a copolymerizable amide monomer, from 1 to 10 % by weight of a copolymerizable carboxylic acid, and a positive amount up to about 6 % by weight of the monomers of a copolymerizable anhydride, said polymer formed thermally reversible crosslinks with a metal cation having a valence of from 2 to 4. Viscosity of the polymer is typically from 2 to 8 Pa.s at 150.degree.C as formed and increases up to 100 Pa.s at 150.degree.C on addition of the metal cation. The figure depicts the temperature profiles from the reactants and the reactor jacket showing the region of heel formation where multiple additions of initiator is used to control, with cooling, reaction temperature and the region where monomer and initiator addition to the formed heel may be continuous or stagewise.
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