US 11,813,823 B2
Multilayer structure, and packaging material for retort using same
Kentaro Yoshida, Kurashiki (JP); and Makoto Suzuki, Kurashiki (JP)
Assigned to KURARAY CO., LTD., Okayama (JP)
Appl. No. 17/438,406
Filed by KURARAY CO., LTD., Okayama (JP)
PCT Filed Mar. 9, 2020, PCT No. PCT/JP2020/010086
§ 371(c)(1), (2) Date Sep. 10, 2021,
PCT Pub. No. WO2020/184523, PCT Pub. Date Sep. 17, 2020.
Claims priority of application No. 2019-043280 (JP), filed on Mar. 11, 2019.
Prior Publication US 2022/0143959 A1, May 12, 2022
Int. Cl. B32B 27/08 (2006.01); B29C 48/00 (2019.01); B29C 48/08 (2019.01); B29C 48/21 (2019.01); B29B 17/04 (2006.01); B29C 55/00 (2006.01); B29C 55/12 (2006.01); B32B 27/30 (2006.01); B32B 27/32 (2006.01); B65D 65/40 (2006.01); C08J 5/18 (2006.01); C08J 11/04 (2006.01); B29K 23/00 (2006.01); B29K 105/00 (2006.01); B29L 7/00 (2006.01); B29L 9/00 (2006.01)
CPC B32B 27/08 (2013.01) [B29B 17/04 (2013.01); B29C 48/0018 (2019.02); B29C 48/022 (2019.02); B29C 48/08 (2019.02); B29C 48/21 (2019.02); B29C 55/005 (2013.01); B29C 55/12 (2013.01); B32B 27/306 (2013.01); B32B 27/32 (2013.01); B65D 65/40 (2013.01); C08J 5/18 (2013.01); C08J 11/04 (2013.01); B29K 2023/086 (2013.01); B29K 2023/12 (2013.01); B29K 2105/0097 (2013.01); B29L 2007/008 (2013.01); B29L 2009/00 (2013.01); B32B 2255/10 (2013.01); B32B 2255/205 (2013.01); B32B 2307/42 (2013.01); B32B 2307/518 (2013.01); B32B 2307/7244 (2013.01); B32B 2307/732 (2013.01); B32B 2553/00 (2013.01); C08J 2323/10 (2013.01); C08J 2329/04 (2013.01); C08J 2377/00 (2013.01)] 18 Claims
 
1. A four or more layered multilayer structure comprising at least an outer layer (A) containing a polypropylene resin (a) as a main component, an inner layer (B) containing a polypropylene resin (b) as a main component, a barrier resin layer (C) containing an ethylene-vinyl alcohol copolymer (c) as a main component, and a metal deposited layer (D) containing aluminum as a main component, wherein
the barrier resin layer (C) and the metal deposited layer (D) are positioned between the outer layer (A) and the inner layer (B);
the total thickness is 200 μm or less;
the polypropylene resin (a) and the polypropylene resin (b) have a melting point of 140° C. or more and less than 170° C., respectively;
the ethylene-vinyl alcohol copolymer (c) has an ethylene unit content of 15 to 60 mol % and a saponification degree of 85 mol % or more; and
the multilayer structure contains neither a layer containing a resin having a melting point of less than 140° C. as a main component, a layer containing a resin having a melting point of 240° C. or more, nor a metal layer having a thickness of 1 μm or more.