Process for the production of general purpose PSA's
AssigneeAvery Dennison Corporation
InventorsIvan S. P. Lee, Charles R. Williams, Colin C. Smith, James R. Bodwell, James P. Akeley
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Abstract
General purpose inherently tacky acrylic pressure sensitive adhesive polymers formed of alkyl acrylates, vinyl esters, diesters of dicarboxylic acid and saturated carbocylic acids, having improved properties, a lower residual monomer content and a reduced polymerization time are formed by a sequential polymerization process in which 50 to 95 percent, typically 90 percent, of the monomers are incrementally added to a reactor as a first charge containing substantially all of the vinyl esters, preferably all of the diesters of dicarboxylic acid, the balance of the monomers being fed in a second incremental charge.
Claims15
A sequential polymerization process for the production of inherently tacky, pressure-sensitive adhesive emulsion polymer particles from a total monomer charge comprising:
- (i) at least one alkyl acrylate containing from about 4 to about 8 carbon atoms in the alkyl group and present in a total amount of 30 to about 65 percent by weight of the monomers;
- (ii) at least one vinyl ester containing from about 2 to about 16 carbon atoms in the alkyl chain of the acid, the total of the vinyl esters being present in an amount of 15 to about 35 percent by weight of the monomers;
- (iii) at least one diester of a dicarboxylic acid present in a total amount of from about 20 to about 85 percent by weight of the monomers, each diester independently containing from 8 to about 16 carbon atoms in the alkyl group of the ester;
- and
- (iv) a positive amount up to about 5 percent by weight of the monomers of at least one unsaturated carboxylic acid;
- said process comprising:
- feeding over a first period of time a first monomer charge containing a portion of the total monomers and a polymerization catalyst to an emulsion polymerization reactor;
- and
- polymerizing the first charge in the presence of the catalyst over at least a portion of the first period of time, wherein the polymerization of the first monomer charge is initiated at a temperature of at least about 65° C.;
- and
- thereafter feeding to the reactor a second monomer charge having a composition different than the first monomer charge and comprising the remainder of the total monomers and polymerizing the second monomer charge in the presence of a catalyst.
Dependencies are inferred from the claim text.