Apparatus for the production of a multi-layer sheet material of microporous structure

Claim 1

Apparatus for use in the continuous production of multi-layer sheet material which comprises at least three containers horizontally-disposed in series with one another, all except the last of said containers having their bottoms in a common horizontal plane and adapted to contain a different solution for treating said sheet material in each container, common partitions dividing said containers from one another, said common partitions each forming a slot between its lower edge and the bottom of all except said last of said containers, aid slots having a width sufficient to accommodate the width of said sheet material and a height sufficient to accommodate the thickness of said sheet material plus the thickness of the layer of treating solution applied in the container preceding said slot, said last of said containers having a bottom substantially below the bottoms of the other of said containers to effect continuous immersion of both sides of said sheet material in the treating solution of said last of said containers as it passes from the slot between the next to the last of said containers and said last of said containers and through said treating solution in said last of said containers and transport means to serially pass said sheet material in a substantially horizontal plane through said containers and said slots and essentially along the bottoms of all but said last of said containers.