Breathable, chemical resistant, durable, and waterproof coated porous membrane

A waterproof, vapor-permeable, air-permeable and chemical resistant sheet material of including:

• a waterproof, vapor-permeable and air-permeable microporous polymerized polymer substrate layer;
• a microporous thermoplastic coating layer attached to the polymer substrate layer, the thermoplastic coating layer being vapor-permeable and air-permeable;
• and
• the thermoplastic coating layer being at least partially interpenetrated into pores of the polymer substrate layer forming an interface that prevents passage of water droplets, while permitting passage of water vapor and air, when a chemical is present on the sheet material that would otherwise cause the polymer substrate layer to permit passage of water droplets;
• wherein the at least partially interpenetrated thermoplastic coating layer into the pores of the polymer substrate layer is provided by heated melt of the thermoplastic coating layer and the heated melt includes heating a first temperature, subsequently heating at a second temperature that is higher than the first temperature, and then subsequently heating at a third temperature that is higher than the second temperature.

A waterproof, vapor-permeable, air-permeable and chemical resistant sheet material including:

• a waterproof, vapor-permeable and air-permeable microporous polymerized polymer substrate sheet layer;
• a microporous thermoplastic sheet layer attached to the polymer substrate, the thermoplastic sheet layer being vapor-permeable and air-permeable;
• and
• the thermoplastic sheet layer being at least partially interpenetrated into pores of the polymer substrate sheet layer forming an interface that is resistant to chemical interference with at least the waterproof property of the sheet material.

A waterproof, vapor-permeable, air-permeable and chemical resistant sheet material including:

• a waterproof, vapor-permeable and air-permeable microporous polymerized polymer substrate layer;
• a microporous thermoplastic coating layer attached to the polymer substrate, the thermoplastic coating layer being vapor-permeable and air-permeable;
• and
• the thermoplastic coating layer being at least partially interpenetrated into pores of the polymer substrate layer forming an interface that is resistant to chemical interference with at least the waterproof property of the sheet material
• wherein the at least partially interpenetrated thermoplastic coating layer into the pores of the polymer substrate layer is provided by heated melt of the thermoplastic coating layer and the heated melt includes heating a first temperature, subsequently heating at a second temperature that is higher than the first temperature, and then subsequently heating at a third temperature that is higher than the second temperature.