초록

A porous sheet comprising a flexible sheet in which a rigid substance is incorporated, wherein pores are formed in the sheet by breaking the rigid substance.

대표청구항 ▼

A liquid impermeable, vapor permeable, porous sheet consisting essentially of a thin, flexible sheet made of non-foamed thermoplastic resin, said sheet having fine pores distributed over the entire surface area of said sheet, said pores penetrating between and through the opposite surfaces of said s

A liquid impermeable, vapor permeable, porous sheet consisting essentially of a thin, flexible sheet made of non-foamed thermoplastic resin, said sheet having fine pores distributed over the entire surface area of said sheet, said pores penetrating between and through the opposite surfaces of said sheet to permit permeation of vapor through said sheet, said pores being of a small size so that liquid cannot substantially permeate through said sheet, said pores each being defined by a cluster of fragments of broken-apart, frangible, filler particles wherein the cluster of fragments extends between said opposite surfaces of said sheet and defines margins of a passage extending between and through said opposite surfaces, the outermost fragments of said cluster being substantially flush with said opposite surfaces of said sheet.