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.

Claims

1. A process for manufacturing membrane modules comprising a polymeric membrane wherein the membrane is substantially unaffected by microwave radiation, 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, wherein the polarisable bonds are capable of being excited by microwave radiation; (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 used to seal the module.

2. (canceled)

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 to 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 and optionally contains imide bonds.

10. (canceled)

11. A process according to claim 9 wherein the organic polymer comprises the following formulation: ##STR00001##

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 or is applied in a plurality of pulses.

17. (canceled)

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.

Description

[0072] FIG. 1 shows the separation performance of the Starmem™122 membranes described in Table 3, Entries 1-7. The separation performance was characterised in terms of rejection, as defined previously in equation 1. The rejections were determined by equation (1) using a solution of polystyrene oligomers in the named solvent, following the method described by See-Toh Y H, Loh X X, Li K, Bismarck A, Livingston A G, “In search of a standard method for the characterisation of organic solvent nanofiltration membranes”, Journal of Membrane Science 2007, Volume 291, pages 120-125. It can be seen in FIG. 1 that the rejection performance of the membranes is consistent across all thermal and microwave curing cycles. I.e. Subjecting the membrane to a curing cycle does not have a negative impact on rejection performance.

[0073] Overall, this shows that using microwaves to attain maximum chemical resistance of an epoxy adhesive system can be successfully applied without affecting the flux and rejection performance of polyimide-based membranes.