Controlled macroporous copolymer properties by removal of impurities in the diluent

Abstract

Macroporous copolymer particles are prepared via a process wherein phase separating diluent is removed from copolymer particles and isolated (e.g., by distillation). The isolated diluent is purified by eluting the diluent through a column containing a purification agent such as alumina. The recycled diluent can be employed in the further preparation of macroporous copolymer particles.

What is claimed is: 
     
       1. In a process for recycling an inert diluent used for preparing macroreticular crosslinked copolymer particles, wherein the copolymer particles are prepared by polymerizing under suspension polymerization conditions a first monomer mixture of a monoethylenically unsaturated monomer and a polyethylenically unsaturated monomer, in the presence of an inert diluent in which the monomer mixture is soluble and the prepared copolymer particles are insoluble, thereby preparing a first batch of macroreticular crosslinked copolymer particles, and then recycling the inert diluent from the first batch to a second batch monomer mixture, the improvement comprises purifying the inert diluent before the recycling step, whereby the resulting macrorecticular crosslinked copolymer particles produced in each batch are substantially consistent in pore size and porosity. 
     
     
       2. The process of claim 1, wherein said purification treatment comprises contacting said diluent with at least a purifying amount of alumina, silica or molecular sieves. 
     
     
       3. The process of claim 1, wherein said diluent is removed from said copolymer particles and isolated using distillation techniques. 
     
     
       4. The process of claim 1, wherein said diluent is a hydrocarbon. 
     
     
       5. The process of claim 1, wherein the monomers comprise monovinylidene aromatics, polyvinylidene aromatics and α,β-ethylenically unsaturated carboxylic acids. 
     
     
       6. The process of claim 1, wherein the monomers are selected from the group consisting of styrene, divinylbenzene and methyl methacrylate. 
     
     
       7. The process of claim 1, wherein an initiator is employed in the polymerization of the monomers. 
     
     
       8. The process of claim 7, wherein the initiator is an azo compound. 
     
     
       9. The process of claim 8, wherein the initiator is azobisisobutyronitrile or peroxygen compound. 
     
     
       10. The process of claim 9, wherein peroxygen compound is benzoyl peroxide, t-butyl peroctoate, t-butyl perbenzoate or isopropylpercarbonate. 
     
     
       11. The process of claim 7, wherein the initiator is employed in amounts from about 0.02 to about 1 weight percent based upon total weight of the monomer mixture. 
     
     
       12. The process of claim 11, wherein the initiator is employed in an amount sufficient to yield about 0.05 weight percent based upon total weight of the monomer mixture.