Internal resin-tackified acrylic polymers
AssigneeExxon Chemical Patents Inc.
InventorHenry W. Yang
Life of this patent
Estimating the term…
Abstract
Acrylic copolymer PSA compositions having enhanced peel strength without substantially decreasing shear properties have been formulated by homogeneously incorporating the tackifying resin into the polymer matrix. The tackifying resin is dissolved into a solution of alkyl (meth) acrylate and (meth) acrylic acid monomers prior to polymerization. To enhance the molecular weight of the resultant PSA, the monomer/tackifier solution is emulsion polymerized in the absence of chain transfer agents, such as antioxidant additives typically found in commercially available tackifiers, and allylic hydrogen present in many unsuitable tackifiers.
Claims8
A method for preparing a tackified acrylic copolymer latex composition which comprises the steps of:
- dissolving from about 10 to about 100 parts by weight of a hydrogenated hydrocarbon resin in 100 parts by weight of a liquid mixture of free-radical polymerizable monomers to form a polymerizable vinyl monomer reactant solution essentially free of chain transfer agent, the hydrocarbon resin having a weight average molecular weight of from about 500 to about 5000 and an aromatic content of at least about 10 percent by weight;
- emulsifying the reactant solution in an aqueous medium;
- polymerizing the emulsified monomers, in the absence of oxygen and chain transfer agent, in the presence of the resin and a free radical polymerization initiator, to form an acrylic copolymer latex;
- and
- recovering the tackified acrylic copolymer latex internally tackified by the resin.
The method of claim wherein the monomers polymerized comprise from 2 to about 6 percent by weight of a (meth) acrylic acid, from about 10 to about 35 percent by weight of a lower alkyl (meth) acrylate and from about 60 to about 88 percent by weight of an upper alkyl (meth) acrylate.
Dependencies are inferred from the claim text.