초록 ▼

A process for the preparation of semipermeable membranes with improved acid and base stability including: (a) coating a base and acid stable ultrafiltration (UF) membrane support polymer, with a high molecular weight amphoteric polyelectrolyte coating polymer optionally in solution, the amphoteric p

A process for the preparation of semipermeable membranes with improved acid and base stability including: (a) coating a base and acid stable ultrafiltration (UF) membrane support polymer, with a high molecular weight amphoteric polyelectrolyte coating polymer optionally in solution, the amphoteric polyelectrolyte containing both cationic and anionic groups and in addition primary and secondary amine groups, the solution optionally containing a latent internal crosslinker compound that is a polyfunctional compound that crosslinks the coating polymer only during a curing step at elevated temperatures and basic pH; (b) draining or washing the coated support; and (c) reacting the coating with a solution of an external crosslinking compound that is a polyfuntional compound, not overly reactive so as not to be hydrolyzed prematurely in solution, the time of exposure to the external crosslinking compound being sufficient to ensure its diffusion into the bulk of the coating, so that the crosslinking is effected not only on the solution-polymer coating interface, but throughout the bulk of the coating as well. The sequence (a)-(c) may optionally be repeated a number of times to give multiple crosslinked layers; draining or washing the coated UF support; and curing the coated membrane by heating at an elevated temperature and basic pH to complete crosslinking by the external crosslinking molecule and if present, also effect crosslinking by the latent internal crosslinker, that is primarily activated only at the elevated temperature conditions.

대표청구항 ▼

[ What we claim is:] [1.] A process for the preparation of semipermeable membranes comprising the steps of:(a) coating a base and acid stable ultrafiltration (UF) membrane support polymer, with an amphoteric polyelectrolyte coating polymer of molecular weight at least about 10,000, whereby to form a

[ What we claim is:] [1.] A process for the preparation of semipermeable membranes comprising the steps of:(a) coating a base and acid stable ultrafiltration (UF) membrane support polymer, with an amphoteric polyelectrolyte coating polymer of molecular weight at least about 10,000, whereby to form a coated support having a first layer of coating;(b) removing excess amphoteric polyelectrolyte coating polymer from said coated support by an action selected from the group of draining said coated support and washing said coated support;(c) contacting said first layer of coating with a solution of an external crosslinking compound that is a polyfunctional compound;(d) removing excess solution containing said external crosslinking compound by an action selected from the group consisting of draining said coated support and washing said coated support; and(e) curing said first layer of coating by heating the coated UF support at an elevated temperature and basic pH,whereby to enable completion of crosslinking by said external crosslinking compound.