Patent ID: 7735660
Filing Date: 2010-06-15
Classification: B01D,Y10T

Abstract:
1. A porous multilayered hollow fiber for outer side pressed filtration of solid-liquid separation treatment, the filtration being performed from the outer surface side thereof toward the internal surface side, comprising: a supporting layer constituted of an expanded porous polytetrafluoroethylene tube (PTFE), and a filtration layer including a porous polytetrafluoroethylene (PTFE) sheet formed by expanding a resin uniaxially or biaxially apart from the supporting layer, the filtration layer being adhered to the outer surface of the supporting layer to form a multilayered body, and pores in the supporting layer three-dimensionally communicating with pores in the filtration layer, wherein pores surrounded by fibrous frameworks in the filtration layer are smaller than those of the supporting layer, and the mean maximum length of pores (L) in the outer surface of the filtration layer is designed such that (X) and (Y) fall within the range defined by plotting the following 10 points on the XY plane, where (X) is a particle diameter of particles captured when the particle trapping ratio is equal to or more than 90% in the case where the filtration is done under an elevated pressure of 0.1 MPa, and (Y) is a value designated as RFL obtained by dividing (L) by (X), that is, (Y=L/X): (X, Y)=(0.055, 2) (1, 1.5) (2, 1) (5, 0.5) (10, 0.3) (10, 4) (5, 6) (2, 10) (1, 15) (0.055, 25).