Monolithic films having zoned breathability

Abstract

Monolithic films are provided having controlled regional breathability with high WVTR regions and low WVTR regions. The zoned monolithic films are be made by selectively applying adhesive to the monolithic film.

We claim:  
     
       1. A method of making a monolithic film having regions of varied breathability comprising: providing a monolithic film wherein said monolithic film has a hydrohead of at least 50 mbars and a WVTR of at least 800 g/m 2 /24 hours; selectively applying adhesive to a portion of said film thereby creating first and second regions within said monolithic film, said second region having dimensions of at least 3 cm by 3 cm and wherein the WVTR is decreased within said second region of said monolithic film relative to the WVTR of said first region. 
     
     
       2. The method of claim  1 , wherein said monolithic film comprises a water-proof moisture-vapor permeable unitary sheet material comprising a monolithic polymeric matrix having continuous passages extending through the thickness of said matrix and opening into both surfaces thereof. 
     
     
       3. The method of claim  1 , wherein said monolithic film comprises a multilayered coating from use in simultaneously imparting liquid resistance and breathability to a textile substrate wherein said coating comprising: 
       a first layer, adjacent to said textile substrate, consisting of a foamed adhesive wherein said adhesive is mechanically formed in solution from a fully reacted polymer latex chosen for the group consisting of polyvinyl chloride, acrylic, polyurethane, polyethylene, polystyrene copolymers of urethane and acrylic monomers, and mixtures thereof, to create an open celled surface;  
       a second layer, coated on said first layer distal to said textile substrate, comprising a monolithic membrane formed from a thermoplastic polymer selected from the group consisting of poly-vinyl diene fluoride, poly-vinyl diene chloride, and thermoplastic polyurethane, said second layer being capable of passing vapor across the width of said second layer in one direction from the surface adjacent to said first layer toward a third layer, and said second layer further being capable of inhibiting the flow of liquid across said second layer in the opposite direction; and,  
       said third layer, coated on said second layer, to inhibit said flow of liquid in the direction of said second layer, and to impart abrasion resistance to said multilayered coating and said textile substrate, said third layer comprising a continuous film formed from latexes selected from the group consisting of acrylics, poly-vinyl chloride, polyurethane, and mixtures thereof.  
     
     
       4. The method of claim  1  wherein the application of adhesive decreases the WVTR of the second region by at least 25% and further wherein said second region has a minimum dimensions of 5 cm by 5 cm. 
     
     
       5. The method of claim  1  wherein the application of adhesive decreases the WVTR of the second region by at least 10% and further wherein said second region has a minimum dimensions of 5 cm by 5 cm. 
     
     
       6. The method of claim  4  wherein said second region comprises from about 5% to about 75% of the area of said monolithic film. 
     
     
       7. The method of claim  1  wherein said WVTR of said first region is at least about 3,000 and said WVTR of said second region is less than about 1,500. 
     
     
       8. The method of claim  6  wherein said thermoplastic polymer comprises a polyolefin polymer and wherein the basis weight of each of said first and second regions is below about 35g/m 2 . 
     
     
       9. The method of claim  1  wherein said first region surrounds said second region. 
     
     
       10. The method of claim  1  wherein said first region partially surrounds said second region. 
     
     
       11. The method of claim  1  wherein said second region is continuous in the machine direction. 
     
     
       12. The method of claim  1  wherein said second region is discontinuous in the machine direction. 
     
     
       13. The method of claim  1  wherein said second region is continuous in the cross-machine direction. 
     
     
       14. The method of claim  1  wherein said second region is discontinuous in the cross-machine direction. 
     
     
       15. The method of claim  1  wherein said adhesive is selectively applied to said second region of said monolithic film in a coat layer. 
     
     
       16. The method of claim  15  wherein said second region comprises between about 5% and 75% of the area of said monolithic film and further wherein said first and second regions of said monolithic film each have a basis weight less than about 35g/m 2 . 
     
     
       17. The method of claim  1  wherein said adhesive applied to said breathable film comprises a first WVTR and a second WVTR wherein first, second, and third regions are created within said monolithic film with said third region having a WVTR intermediate to the WVTR of said first and second regions. 
     
     
       18. The method of claim  16  wherein said second region comprises from about 5% to about 75% of said monolithic film. 
     
     
       19. The method of claim  17  wherein said second and third regions are continuous. 
     
     
       20. The method of claim  18  wherein said monolithic film has a WVTR gradient. 
     
     
       21. The method of claim  1  further comprising the step of laminating a nonwoven web to said monolithic film prior to applying said adhesive. 
     
     
       22. The method of claim  6  further comprising the step of laminating a nonwoven web to said monolithic film prior to applying said adhesive.