Patent ID: 7081273

Claim:
A method for producing a defect free composite membrane comprising: (i) preparing a solution A comprising a chemical, which are selected from the group consisting of epoxy, polyurethane, silicone, adhesives, monomers, polymers, and combinations thereof; (ii) preparing a solution B comprising 8–60% of a hydrophobic polymer, 1–20% of a hydrophilic polymer, 1–20% of inorganic additive, 1–10% of monomers, 1–10% of organic additives, and solvents; (iii) providing a support; (iv) coating said support at a speed from 5 to 3,000 ft/min with solution A and solution B simultaneously using a spinneret; wherein the support is first contacted with said solution A to form a first layer on said support, and said first layer is coated with solution B to form a second layer on top of the first layer; (v) applying vacuum to the support either prior or during coating; (vi) coagulating said coating layers on top of said support in a coagulation bath stirred with an ultrasonic device to form a defect free composite membrane; (vii) removing said solvent and additives from said membrane in a series of leaching baths stirred with submersible ultrasonic cleaner; (viii) controlling and monitoring coating thickness and consistency by a laser sensor and feeding a signal back to a solution delivery system to give a desired membrane thickness; (ix) collecting said membrane at a speed of 5 to 3,000 ft/min with a take-up wheel immersed in a water bath agitated with an ultrasonic sonicator to remove chemical residual from said membrane; (x) switching to another take-up wheel when one wheel is full to continue collecting said membrane around clock; (xi) curing said membrane either at ambient temperature or at an elevated temperature depending on the chemical compound used in solution A to bond said support and said membrane together.