Plug flow bulk polymerization of vinyl monomers

Abstract

A process for continuous bulk polymerization is disclosed that includes providing a plug flow reactor comprising a primary loop reactor including a loop for recirculating a portion of a polymer-in-progress at a polymer flow rate back to a reactor in the primary loop reactor, introducing at least one monomer into the primary recirculation loop reactor at a monomer flow rate, polymerizing the monomer in the primary recirculation loop reactor in the presence of an initiator by way of a free-radical polymerization to form a polymer-in-progress, and recirculating a first portion of the polymer-in-progress through the loop into a reactor in the primary loop reactor to combine with the monomer at a ratio of polymer flow rate to monomer flow rate that is greater than 5.

1 . A process for continuous bulk polymerization, the process comprising:
 providing a plug flow reactor comprising a primary loop reactor including a loop for recirculating a portion of a polymer-in-progress at a polymer flow rate back to a reactor in the primary loop reactor;   introducing at least one monomer into the primary recirculation loop reactor at a monomer flow rate;   polymerizing the monomer in the primary recirculation loop reactor in the presence of an initiator by way of a free-radical polymerization to form a polymer-in-progress; and   recirculating a first portion of the polymer-in-progress through the loop into a reactor in the primary loop reactor to combine with the monomer at a ratio of polymer flow rate to monomer flow rate that is greater than 5.   
   
   
       2 . The process of  claim 1  wherein the ratio of the polymer flow rate to the monomer flow rate is greater than 10. 
   
   
       3 . The process of  claim 1  wherein the ratio of the polymer flow rate to the monomer flow rate is greater than 15. 
   
   
       4 . The process of  claim 1  wherein the primary recirculation loop reactor includes only static mixers. 
   
   
       5 . The process of  claim 1  wherein the primary recirculation loop reactor includes at least one planetary roller extruder. 
   
   
       6 . The process of  claim 5  wherein the monomer and the recirculating first portion of the polymer-in-progress are combined in the planetary roller extruder. 
   
   
       7 . The process of  claim 5  wherein the primary loop reactor further includes at least one static mixer. 
   
   
       8 . The process of  claim 1  further comprising a secondary loop reactor including a loop for recirculating a portion of a polymer-in-progress or a secondary reactor coupled to the primary loop reactor and further polymerizing a second portion of the polymer-in-progress in the secondary reactor or the secondary recirculation loop reactor to form a resulting polymer. 
   
   
       9 . The process of  claim 8  wherein the monomers are at least 70% converted to polymer in the primary recirculation loop reactor and are at least 94% converted to polymer in the secondary reactor or the secondary loop reactor. 
   
   
       10 . The process of  claim 8  wherein the monomers are at least 80% converted to polymer by the primary loop reactor and are at least 95% converted to polymer by the secondary reactor or the secondary loop reactor. 
   
   
       11 . The process of  claim 10  wherein the monomers are at least 98% converted to polymer by the secondary reactor or the secondary loop reactor. 
   
   
       12 . The process of  claim 8  wherein the primary loop reactor is coupled to the secondary reactor and the secondary reactor is a planetary roller extruder. 
   
   
       13 . The process of  claim 8  wherein the primary loop reactor is coupled to the secondary loop reactor and the secondary loop reactor includes a static mixer. 
   
   
       14 . The process of  claim 1  wherein introducing at least one monomer includes introducing an acrylic monomer. 
   
   
       15 . The process of  claim 14  wherein the acrylic monomer is butyl acrylate. 
   
   
       16 . The process of  claim 1  wherein introducing at least one monomer includes introducing a butyl acrylate monomer and a vinyl acetate monomer. 
   
   
       17 . The process of  claim 16  wherein the initiator is azo-diisobutyronitrile. 
   
   
       18 . The process of  claim 17  wherein introducing further comprises introducing an acrylic acid and a mercaptan-type chain transfer agent into the primary recirculation loop reactor. 
   
   
       19 . The process of  claim 18  wherein the mercaptan-type chain transfer agent is a dodecylmercaptan. 
   
   
       20 . The process of  claim 1  further comprising heating the contents of both the primary recirculating loop reactor and the secondary reactor or secondary recirculating loop reactor to no more than about 120° C. 
   
   
       21 . The process of  claim 1  further comprising heating the contents of both the primary recirculating loop reactor and the secondary reactor or secondary recirculating loop reactor to no more than about 100° C. 
   
   
       22 . The process of  claim 1  further comprising heating the contents of both the primary recirculating loop reactor and the secondary reactor or secondary recirculating loop reactor to no more than about 80° C. 
   
   
       23 . The process of  claim 1  wherein the resulting polymer is an adhesive. 
   
   
       24 . The process of  claim 1  wherein the resulting polymer is a pressure-sensitive adhesive. 
   
   
       25 . The process of  claim 1  wherein the resulting polymer has a molecular weight of up to about 300,000. 
   
   
       26 . The process of  claim 1  wherein the resulting polymer has a molecular weight of about 225,000 to about 300,000. 
   
   
       27 . The process of  claim 1  wherein the resulting polymer has a polydispersity of about 1.2 to about 3.0. 
   
   
       28 . The process of  claim 1  wherein the resulting polymer has a polydispersity of about 1.5 to about 2.5. 
   
   
       29 . The process of  claim 1  wherein the process is solvent-free. 
   
   
       30 . A process for continuous bulk polymerization, the process comprising:
 providing a plug flow reactor comprising a primary loop reactor including a loop for recirculating a portion of a polymer-in-progress at a polymer flow rate back to a reactor in the primary loop reactor;   introducing a butyl acrylate monomer into the primary recirculation loop reactor at a monomer flow rate;   polymerizing the monomer in the primary recirculation loop reactor in the presence of an initiator by way of a free-radical polymerization to form a polymer-in-progress; and   recirculating a first portion of the polymer-in-progress through the loop into a reactor in the primary loop reactor to combine with the monomer at a ratio of polymer flow rate to monomer flow rate that is greater than 5;   wherein the resulting polymer has a molecular weight of about 225,000 to about 300,000 and a polydispersity of about 1.2 to about 3.0.   
   
   
       31 . The process of  claim 30  wherein the ratio of the polymer flow rate to the monomer flow rate is greater than 10. 
   
   
       32 . The process of  claim 30  wherein the ratio of the polymer flow rate to the monomer flow rate is greater than 15. 
   
   
       33 . The process of  claim 30  further comprising a secondary loop reactor including a loop for recirculating a portion of a polymer-in-progress or a secondary reactor coupled to the primary loop reactor and further polymerizing a second portion of the polymer-in-progress in the secondary reactor or the secondary recirculation loop reactor to form a resulting polymer. 
   
   
       34 . The process of  claim 30  wherein introducing also includes introducing a vinyl acetate monomer, acrylic acid, and a chain transfer agent. 
   
   
       35 . The process of  claim 34  wherein the initiator is azo-diisobutyronitrile and the chain transfer agent is a mercaptan. 
   
   
       36 . The process of  claim 30  wherein the resulting polymer has a polydispersity of about 1.5 to about 2.5. 
   
   
       37 . The process of  claim 30  wherein the process is solvent-free.