Waterproof, moisture-vapor permeable sheet material and method of making the same
AssigneeMinnesota Mining and Manufacturing Company
InventorMalcolm B. Burleigh
Life of this patent
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Abstract
A waterproof, moisture-vapor permeable unitary sheet material comprises a microporous polymeric matrix having pores comprising continuous passages extending through its thickness and opening into the opposite surfaces thereof, the passages being sufficiently filled with a moisture-vapor permeable, water-impermeable, hydrophilic material to prevent the passage of water and other liquids through the unitary sheet material while readily permitting moisture vapor transmission therethrough rendering the sheet material breathable. The unitary sheet is made by causing a liquid composition comprising the hydrophilic material or precursor thereof to flow into the pores of the matrix, then causing the conversion thereof to solid hydrophilic material.
Claims15
A waterproof, moisture-vapor permeable unitary sheet material comprising a microporous polymeric matrix having continuous pores comprising continuous passages extending through its thickness and opening into both surfaces thereof, said pores being sufficiently filled with a moisture-vapor permeable, water-impermeable, hydrophilic material to prevent the passage of water through said unitary sheet material.
A two phase, homogeneous, waterproof, moisture-vapor permeable, unitary sheet material comprising a microporous polymeric first phase having pores comprising continuous passages opening into the opposite surfaces thereof, and a second phase comprising moisture-vapor permeable, water impermeable, hydrophilic material sufficiently filling said pores to prevent the passage of water through said unitary sheet material.
Method of making a waterproof, moisture-vapor permeable unitary sheet material, said method comprising the steps of:
- (a) providing a microporous polymeric matrix having pores extending through its thickness;
- (b) selecting a hydrophilic material or precursor thereof which when converted to said hydrophilic material is moisture-vapor permeable and water-impermeable;
- (c) preparing a liquid composition comprising said hydrophilic material or a precursor thereof for flowing into the pores of said matrix;
- (d) if needed, rendering the polymeric surface of said matrix wettable to said liquid composition;
- (e) causing the liquid composition to flow into the pores of said matrix;
- and
- (f) causing said hydrophilic material or precursor thereof to convert to solid hydrophilic material within said pores to sufficiently fill said pores to prevent the passage of water through said unitary sheet material.
Dependencies are inferred from the claim text.