Support substrate for separation membrane

Abstract

A separation membrane support substrate comprising (1) a front layer having at least one layer comprising thermoplastic resin filaments with a single filament diameter of 7-30 μm; (2) a middle layer having at least one layer comprising melt blown fibers with a single fiber diameter of no greater than 5 μm, and a fiber basis weight of at least 1 g/m 2 and comprising no more than 30 wt % of the total fiber basis weight; (3) a back layer having at least one layer comprising thermoplastic resin filaments with a single filament diameter of 7-20 μm, and has a fiber basis weight of 3-40 g/m 2 ; (4) the laminated nonwoven fabric has an apparent density of 0.67-0.91 g/cm 3 ; and (5) the laminated nonwoven fabric has a thickness of 45-110 μm.

1 - 8 . (canceled) 
     
     
         9 . A process for production of a separation membrane support substrate comprising
 (a) spinning a thermoplastic resin filament on a conveyor using a thermoplastic resin with a melting point of 180° C. or higher to form at least one nonwoven fabric layer,   (b) laminating at least one layer of fibers with a crystallinity of 15-40% and a fiber diameter of no greater than 5 μm, composed of a thermoplastic resin with a melting point of 180° C. or higher by melt blowing said fibers over said at least one nonwoven fabric layer,   (c) laminating to said at least one layer formed by melt blowing, at least one layer of nonwoven fabric of thermoplastic resin filaments composed of a thermoplastic resin with a melting point of 180° C. or higher, and   (d) heat bonding at a temperature of 50-120° C. below the melting point of the thermoplastic resin filaments using a flat roll at a line pressure of 100-1000 N/cm, after which a calender treatment is carried out at a temperature of at least 10° C. higher than the temperature of said heat bonding and 10-100° C. lower than the melting point of the thermoplastic resin filaments, at a line pressure of 100-1000 N/cm.   
     
     
         10 . A process for production of a separation membrane support substrate according to  claim 9 , wherein the thermoplastic resin is a polyester-based resin.