US 11,674,026 B2
Polyolefin-based microporous films via sequential cold and hot stretching of unannealed polypropylene copolymer films
Wenyi Huang, Midland, MI (US); and William Ripmeester, Kingston (CA)
Assigned to DDP SPECIALTY ELECTRONIC MATERIALS US, LLC, Wilmington, DE (US)
Filed by DDP SPECIALTY ELECTRONIC MATERIALS US, LLC, Wilmington, DE (US)
Filed on Mar. 18, 2021, as Appl. No. 17/205,438.
Prior Publication US 2022/0298340 A1, Sep. 22, 2022
Int. Cl. C08L 23/12 (2006.01); C08L 23/16 (2006.01); C08J 5/18 (2006.01)
CPC C08L 23/12 (2013.01) [C08J 5/18 (2013.01); C08L 23/16 (2013.01); C08J 2323/12 (2013.01); C08J 2323/16 (2013.01); C08J 2423/12 (2013.01); C08J 2423/16 (2013.01); C08L 2203/162 (2013.01)] 31 Claims
 
1. A microporous polymer film comprising:
(a) 50 to 95 weight percent of one or more polypropylene copolymer, based on the total weight of the film, said polypropylene copolymer comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments; and wherein the microporous polymer film comprises:
(i) polypropylene homopolymer chain segments in total amount of from 50-82 wt. %, based on the weight of polypropylene copolymer, or from 43-79 mole %, based on the mole content of polymerized units of propylene in the polypropylene homopolymer chain segments as a percentage of the total mole content of polymerized monomer units in the polypropylene copolymer; and
(ii) ethylene-containing copolymer chain segments in total amount of from 18-50 wt. %, based on the weight of polypropylene copolymer, or from 21-57 mole %, based on the mole content of polymerized monomer units in the ethylene-containing copolymer chain segments as a percentage of the total mole content of polymerized monomer units in the polypropylene copolymer; wherein at least a portion of the ethylene-containing copolymer chain segments comprise polymerized units of ethylene in an amount of at least 45 wt. %, based on the weight of the ethylene-containing copolymer chain segments, or at least 55 mole % based on the mole content of polymerized units of ethylene in the ethylene-containing copolymer chain segments as a percentage of the total mole content of polymerized monomer units in the ethylene-containing copolymer chain segments; and
(b) 5 to 50 weight percent of one or more ethylene-propylene elastomer, based on the total weight of the film;
wherein at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are units of ethylene.