Process for the polymerization of acrylates

Claim 1

A continuous solution process for the polymerization of monomers comprising at least 40 percent arylate esters of C 1 to C 8 alkanols which comprises: (a) introducing monomer, initiator and chain transfer agent into admixture with solvent to provide a polymerization medium containing not less than 40 weight percent solvent; (b) maintaining said polymerization medium under polymerization conditions, in at least one polymerization reactor comprising a temperature from 60 to about 130 degrees C. and sufficient residence time to effect 20 to 95 percent of the total conversion of said monomer and form a crude intermediate polymerizate; (c) withdrawing said crude, intermediate polymerizate and passing it to at least one succeeding polymerization reactor, including a final polymerization reactor; (d) stirring said crude intermediate polymerizate in said succeeding polymerization reactor, including said final polymerization reactor, to maintain said polymerizate intimately admixed while maintaining polymerization conditions therein comprising a temperature from 60 to about 130 degrees C., and sufficient residence time to essentially deplete the initiator in said polymerizate, thereby forming, and pumping a crude polymerizate containing solvent, unreacted monomer and less than about 50 weight percent polymer from said final polymerization reactor; (e) heating said crude polymerizate in a devolatilzer preheater to a temperature between 200 degrees and 270 degrees C., withdrawing the preheated crude polymerizate from said preheater and passing it through a transfer line to a devolatilizer and spraying said preheated polymerizate into said devolatilizer and, flashing the polymerizate therein to remove a volatile stream comprising solvent, unreacted monomer, and oligomers therefrom; and (f) maintaining a pressure on the crude polymerizate in said transfer line and said devolatilizer preheater which permits vaporization therein to form a mixed two-phase system of vapor and liquid, which pressure is sufficient to prevent incipient solidification in the liquid phase, thereby avoiding formation of foam encrustations on the heat exchange surfaces of said preheater, while heating said polymerizate sufficiently in said preheater to provide a preheated crude polymerizate with sufficient heat to supply the heat of vaporization necessary to produce said molten polymer and permit it to be pumped from said devolatilizer.

Claim 17

The method for the devolatilization of a crude polymerizate of poly(acrylate esters) containing solvent, unreacted monomer and less than about 50 weight percent polymer which comprises: (a) heating said crude polymerizate by indirect heat exchange in a devolatilzer preheater to a temperature between about 200 and 270 degrees C.; (b) controlling the pressure on the crude polymerizate in said devolatilizer preheater at a value which permits vaporization therein to form a mixed two-phase system of vapor and liquid, which pressure is sufficient to prevent incipient solidification in the liquid phase, thereby avoiding formation of foam encrustations on the heat exchange surfaces of said preheater, while heating said polymerizate sufficiently in said preheater to provide a preheated crude polymerizate with sufficient heat to supply the heat of vaporization necessary to produce said molten polymer and permit it to be pumped from said devolatilizer; (c) passing said preheated polymerizate through a transfer line into a devolatilizer vessel and flashing the polymerizate therein to form a volatile stream comprising solvent, unreacted monomer, and oligomers; and (d) withdrawing from the devolatilized a molten polymer containing less than 1.0 weight percent solvent and unreacted monomer.

Claim 18

The method for the devolatilization of a crude polymerizate of poly(acrylate esters) containing solvent, unreacted monomer and less than about 50 weight percent polymer which comprises: (a) heating said crude polymerizate by indirect heat exchange in a devolatilzer preheater to a temperature between about 200 and 270 degrees C.; (b) controlling the pressure on the crude polymerizate in said devolatilizer preheater at a value which permits vaporization therein to form a mixed two-phase system of vapor and liquid, which pressure is sufficient to prevent incipient solidification in the liquid phase, thereby avoiding formation of foam encrustations on the heat exchange surfaces of said preheater, while heating said polymerizate sufficiently in said preheater to provide a preheated crude polymerizate with sufficient heat to supply the heat of vaporization necessary to produce said molten polymer and permit it to be pumped from said devolatilizer; (c) passing said preheated polymerizate through a transfer line into a devolatilizer vessel and flashing the polymerizate therein to form a volatile stream comprising solvent, unreacted monomer, and oligomers; and (d) withdrawing from the devolatilized a molten polymer containing less than 1.0 weight percent solvent and unreacted monomer.