US Patent 11529787 Multilayer tubes

A multilayer tube is provided which includes a layer including a specific aliphatic polyamide composition and a layer including a semi-aromatic polyamide composition including a semi-aromatic polyamide with a specific structure, these layers being adjacent to each other, wherein the aliphatic polyamide composition includes an aliphatic polyamide having a specific ratio of the number of methylene groups to the number of amide groups, a polyamide having a specific difference in absolute value of solubility parameter SP from the aliphatic polyamide, and an elastomer polymer including a structural unit derived from an unsaturated compound having a carboxyl group and/or an acid anhydride group.