Polyolefin foam/film composite and method for making the same

Abstract

A composite structure, which includes: a. a foam sheet comprising polyolefin; and b. a film sheet adhered to the foam sheet, wherein the film sheet (1) comprises polypropylene, (2) is stretch-oriented in at least one direction, (3) has a thickness of less than 0.9 mil, and (4) has a larger surface area than the foam sheet such that at least one edge of the film sheet extends beyond a corresponding edge of the foam sheet.

What is claimed is:  
     
       1. A composite structure, comprising: 
       a. a foam sheet comprising polyolefin; and  
       b. a film sheet adhered to said foam sheet, wherein said film sheet  
       (1) comprises polypropylene,  
       (2) is stretch-oriented in at least one direction,  
       (3) has a thickness of less than 0.9 mil, and  
       (4) has a larger surface area than said foam sheet such that at least one edge of said film sheet extends beyond a corresponding edge of said foam sheet.  
     
     
       2. The composite structure of  claim 1 , wherein said polyolefin foam sheet comprises polyethylene homopolymer or copolymer. 
     
     
       3. The composite structure of  claim 2 , wherein said polyolefin foam sheet has a density ranging from about 1 to about 10 pounds/ft 3  and a thickness ranging from about 0.004 to about 2 inches. 
     
     
       4. The composite structure of  claim 1 , wherein said film sheet is stretch-oriented in at least two directions. 
     
     
       5. The composite structure of  claim 4 , wherein said film sheet has an orientation ratio of at least 2 in both of said at least two directions. 
     
     
       6. The composite structure of  claim 1 , wherein said film has a thickness 0.6 mil or less. 
     
     
       7. The composite structure of  claim 1 , wherein said film includes at least a first layer comprising said polypropylene and a second layer interposed between and bonding said film and foam sheets. 
     
     
       8. The composite structure of  claim 7 , wherein said foam sheet and film sheet are adhered via heat lamination. 
     
     
       9. The composite structure of  claim 1 , wherein said composite structure has a maximum water vapor transmission rate of 0.6 grams/100 in 2  per 24 hours @ 100° F. and 90% relative humidity. 
     
     
       10. The composite structure of  claim 9 , wherein said composite structure has a maximum water vapor transmission rate of 0.5 grams/100 in 2  per 24 hours @ 100° F. and 90% relative humidity. 
     
     
       11. A method for making a composite structure, comprising: 
       a. providing a foam sheet comprising polyolefin; and  
       b. providing a film sheet and adhering said film sheet to said foam sheet, wherein said film sheet  
       (1) comprises polypropylene,  
       (2) is stretch-oriented in at least one direction,  
       (3) has a thickness of less than 0.9 mil, and  
       (4) has a larger surface area than said foam sheet such that at least one edge of said film sheet extends beyond a corresponding edge of said foam sheet.  
     
     
       12. The method of  claim 11 , wherein said polyolefin foam sheet comprises polyethylene homopolymer or copolymer. 
     
     
       13. The method of  claim 12 , wherein said polyolefin foam sheet has a density ranging from about 1 to about 10 pounds/ft 3  and a thickness ranging from about 0.004 to about 2 inches. 
     
     
       14. The method of  claim 11 , wherein said film sheet is stretch-oriented in at least two directions. 
     
     
       15. The method of  claim 14 , wherein said film sheet has an orientation ratio of at least 2 in both of said at least two directions. 
     
     
       16. The method of  claim 11 , wherein said film has a thickness 0.6 mil or less. 
     
     
       17. The method of  claim 11 , wherein said film includes at least a first layer comprising said polypropylene and a second layer interposed between and bonding said film and foam sheets. 
     
     
       18. The method of  claim 17 , wherein said foam sheet and film sheet are adhered via heat lamination. 
     
     
       19. The method of  claim 11 , wherein said composite structure has a maximum water vapor transmission rate of 0.6 grams/100 in 2  per 24 hours @ 100° F. and 90% relative humidity. 
     
     
       20. The method of  claim 19 , wherein said composite structure has a maximum water vapor transmission rate of 0.5 grams/100 in 2  per 24 hours @ 100° F. and 90% relative humidity.