Method for improving membrance coating properties for ion exchange membrane applications and woven mesh fabric having improved membrane coating properties for ion exchange membrane applications

A method for improving membrane coating properties for ion exchange membrane applications with a woven mesh fabric as a reinforcement fabric, the woven mesh fabric comprising warp and weft monofilament fibers of at least one of the following polymers:

• polyphenylene sulfide, polyether ether ketone, perfluoroalkoxy alkanes, fluorinated ethylene propylene and liquid crystal polyester, wherein one monofilament fiber is made of only one of the polymers,
• wherein the method comprises:
• a fixation step, which is carried out after weaving of the woven mesh fabric, wherein the woven mesh fabric is subjected to at least one thermal treatment between 240° C. and 350° C. to fix the mesh opening into desired dimensions and stabilize the monofilament fibers of the woven mesh fabric as well as to remove surface contaminants from the monofilament fibers, one or more preparation steps are carried out comprising:
• a plasma pre-treatment step of the woven mesh fabric is carried out for further fine cleaning the surface of the woven mesh fabric especially by removal of impurities, strong adhering dust particles and organic, inorganic and microbial contaminants from the filament surface,
• a plasma etching step of exposing the woven mesh fabric to plasma for etching the surface of the monofilament fibers of the woven mesh fabric to an average roughness between 30 nm and 200 nm,
• a subsequent coating step of depositing a plasma coating on the woven mesh fabric by means of plasma polymerization incorporating functional groups at least one selected from a group consisting of hydroxyl group, carboxyl group, amino group and sulfonate group,
• wherein one or more preparation steps and coating step are performed in a plasma chamber having a plurality of rollers in a roll to roll system which operates with a radiofrequency of about 13.56 MHz, having a first electrode set and a second electrode set within the plasma chamber, and the woven mesh fabric being passed through plasma zones between the electrode sets, thereby having treatment on both sides of the woven mesh fabric,
• wherein the woven mesh fabric comprises a filament diameter between 10 μm and 60 μm and a mesh opening of 20 μm or more and having a fabric thickness between 20 μm and 80 μm.