US 12,409,640 B2
Waterproofing and breathable polyolefin roofing membrane by extrusion lamination and sequential stretching
Wenyi Huang, Wilmington, DE (US); Lisa Bertolo, Kingston (CA); and Jiaqi Wang, Shanghai (CN)
Filed by DDP SPECIALTY ELECTRONIC MATERIALS US, LLC., Wilmington, DE (US); EIDCA SPECIALTY PRODUCTS COMPANY, Kingston (CA); and DUPONT (CHINA) RESEARCH & DEVELOPMENT AND MANAGEMENT CO., LTD., Shanghai (CN)
Filed on May 4, 2023, as Appl. No. 18/312,123.
Prior Publication US 2023/0356516 A1, Nov. 9, 2023
Int. Cl. B32B 27/12 (2006.01); B29C 48/00 (2019.01); B29C 48/07 (2019.01); B29C 48/154 (2019.01); B29C 71/02 (2006.01); B32B 5/02 (2006.01); B32B 27/32 (2006.01); B32B 37/15 (2006.01); B32B 38/00 (2006.01); B29K 23/00 (2006.01); B29K 105/00 (2006.01); E04D 5/10 (2006.01)
CPC B32B 27/12 (2013.01) [B29C 48/0018 (2019.02); B29C 48/07 (2019.02); B29C 48/154 (2019.02); B29C 71/02 (2013.01); B32B 5/022 (2013.01); B32B 27/32 (2013.01); B32B 37/153 (2013.01); B32B 38/0012 (2013.01); B32B 38/0036 (2013.01); B29C 2071/022 (2013.01); B29K 2023/06 (2013.01); B29K 2023/12 (2013.01); B29K 2105/0088 (2013.01); B29K 2713/00 (2013.01); B32B 2038/0028 (2013.01); B32B 2038/0048 (2013.01); B32B 2250/40 (2013.01); B32B 2260/021 (2013.01); B32B 2260/046 (2013.01); B32B 2262/0253 (2013.01); B32B 2262/0276 (2013.01); B32B 2262/124 (2021.05); B32B 2270/00 (2013.01); B32B 2305/18 (2013.01); B32B 2307/516 (2013.01); B32B 2307/518 (2013.01); B32B 2307/54 (2013.01); B32B 2307/718 (2013.01); B32B 2307/7246 (2013.01); B32B 2307/7376 (2023.05); B32B 2307/748 (2013.01); B32B 2323/10 (2013.01); B32B 2419/06 (2013.01); E04D 5/10 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A method for forming a reinforced microporous polyolefin sheet, comprising the steps of:
a) extrusion laminating a non-porous sheet of a polyolefin onto at least one side of a non-woven fabric to produce a non-porous laminate having a thickness of at least 1 mm, the non-porous laminate comprising the non-woven fabric at least partially embedded in the polyolefin, then
b) subjecting the non-porous laminate to sequential stretching steps to produce micropores in the polyolefin, the stretching steps comprising
1) At least one cold stretching step at a temperature in the range of −20° C. to 50° C. and
2) At least one hot stretching step at a temperature greater than 50° C. and up to 150° C.,
wherein the non-woven fabric has an area weight of 100 to 400 g/m2, a thickness of 0.25 to 0.95 mm under a load of 2 kN/m2, and an elongation to break of 30 to 200% in each of machine and cross directions and
wherein the polyolefin is a phase-segregated polymer that comprises a continuous phase comprising a polypropylene homopolymer, and a dispersed phase comprising an ethylene-propylene copolymer having a glass transition temperature of −30° C. or lower, the dispersed phase further containing inclusions of a polypropylene homopolymer.