Porous membrane

摘要

The purpose of the present invention is to provide a porous membrane by which a useful component can be collected while suppressing the clogging during filtration of a protein solution and from which only a small amount of an eluate is eluted in the case of filtering an aqueous solution. Provided is a porous membrane that comprises a hydrophobic polymer and a water-insoluble hydrophilic polymer, said porous membrane being provided with a dense layer disposed on the downstream of a filtration site of the membrane, having an inclined asymmetric structure wherein the average pore size of micropores increases from the downstream of the filtration site toward the upstream of the filtration site, and having an inclination index of the average pore size from the dense layer to the coarse layer of 0.5-12.0