Membrane module

Abstract

The present invention relates to a method for curing adhesives used in the manufacture of membrane modules containing polymeric membranes, particularly polyimide based membranes used for the nanofiltration or ultrafiltration of solutes dissolved in organic solvents using microwaves. To maximise the chemical resistance of the adhesive used in these organic solvent applications, it must be as fully reacted and crosslinked (“cured”) as possible. Typically, thermal processing (heating) of the entire membrane module is used to cure the adhesives. However, the time and temperature required to achieve this high degree of completion of reaction may damage the separation performance of the membrane contained within the membrane module. In one particular aspect, this process utilises microwaves to preferentially promote the curing of epoxy adhesives over the general heating of the membrane module.

1 . A process for manufacturing membrane modules comprising an adhesive containing functional groups capable of being excited by microwaves, a source of microwaves, a membrane material that is substantially unaffected by microwave radiation, and additional membrane module components that are not affected by microwave radiation, the process comprising the step of applying microwave radiation to the adhesive in the presence of the membrane material. 
     
     
         2 . A process as claimed in  claim 1  for manufacturing a membrane module comprising a polymeric membrane, a feed spacer, a permeate spacer, a permeate tube, and end caps, the process comprising the steps of:
 (a) applying an adhesive containing one or more polarisable bonds to the polymeric membrane; 
 (b) positioning the polymeric membrane in its desired location within the membrane module to produce a green membrane module ensemble; and 
 (c) applying microwave radiation to the green ensemble to cure the adhesive. 
 
     
     
         3 . A process according to  claim 1  wherein the adhesive requires heating at temperatures above 40 deg.C. to fully cure. 
     
     
         4 . A process according to  claim 1 , wherein the adhesive contains functional groups capable of being excited by microwave radiation. 
     
     
         5 . A process according to  claim 1  wherein the adhesive contains epoxy functional groups. 
     
     
         6 . A process according to  claim 1  wherein the adhesive contains epoxy resins based on the diglycidylether of bis-phenol A (DGEBA) or diglycidylether of bis-phenol F (DGEBF) or glycidyl ether of a phenolic novolac resin (novolac epoxy resins). 
     
     
         7 . A process according to  claim 1  wherein the adhesive requires a curing agent based on an aliphatic amine or an aromatic amine or a polyamide or an aminoamide or a mercaptan or a polysulphide or a latent curing agent or an anhydride or a catalytic curing agent for the adhesive to cure. 
     
     
         8 . A process according to  claim 1  wherein the adhesive requires greater than 0.1 hour to fully cure. 
     
     
         9 . A process according to  claim 1  wherein the membrane material consists of an organic polymer material. 
     
     
         10 . A process according to  claim 9  wherein the organic polymer contains imide bonds. 
     
     
         11 . A process according to  claim 9  wherein the organic polymer comprises the following formulation: 
       
         
           
           
               
               
           
         
       
     
     
         12 . A process according to  claim 1  in which the microwave radiation is in the frequency range 1 to 100 GHz. 
     
     
         13 . A process according to  claim 1  in which the power of the microwave source is in the range 50 W to 5 kW. 
     
     
         14 . A process according to  claim 1  in which the microwave radiation is switched so that it is applied in discrete time intervals. 
     
     
         15 . A process according to  claim 14 , wherein the discrete time interval is from 1 second to 10 minutes. 
     
     
         16 . A process according to  claim 14 , wherein radiation is applied for a single time interval. 
     
     
         17 . A process according to  claim 14 , wherein radiation is applied in a plurality of pulses. 
     
     
         18 . A process according to  claim 1  in which the frequency of the microwave radiation is modulated. 
     
     
         19 . A membrane module produced by the process of  claim 1  that is a solvent stable membrane module containing polyimide-based ultrafiltration or nanofiltration membranes. 
     
     
         20 . A membrane material according to  claim 19  that is capable of nanofiltration or ultrafiltration in organic solvents. 
     
     
         21 . A membrane material according to  claim 19  that incorporates a conditioning agent that does not contain bonds polarisable in the presence of microwave radiation. 
     
     
         22 . A membrane material according to  claim 19  that does not require the incorporation of a conditioning agent.