The invention discloses a method for preparing hollow
fiber membranes and tubular membranes with a microporous PTFE
hybrid flat membrane wrapping method. Dispersed PTFE resin and
polyvinylidene fluoride resin are mixed with a liquid
lubricant, and microporous PTFE
hybrid flat membranes are prepared from the mixture through
extrusion, calendaring, stretching and
sintering. Then the microporous PTFE
hybrid flat membranes are
cut into membrane strips which
wrap around supporting tubes, and finally the wrapped supporting tubes are sintered to obtain the hollow
fiber membranes and the tubular membranes. The
polyvinylidene fluoride resin added into the products of the invention has a
melting point around 160 DEG C, fuses while sintered at a temperature between 250 and 340 DEG C, and can largely increase the
hardness of the flat membranes after solidification, which facilitates slitting of the flat membranes. During the process of
sintering after wrapping, the
polyvinylidene fluoride resin contained in the flat membranes fuses again when sintered at a temperature between 260 and 340 DEG C, and thus can be used as overlapping parts between the wrapped flat membranes and as binders between the flat membranes and the microporous supporting tubes, so that the
bonding strength is substantially improved.