Patent ID: 9393721
Filing Date: 2016-07-19
CPC Classification: B29C,B29K,B32B,C08G,C08L,H05K

Claim Text:
1. A method for producing a three-layer coextrusion polyimide film by cast-flowing polyamic acid solutions onto a support by three-layer coextrusion, the three-layer coextrusion polyimide film including, in lamination, a non-thermoplastic polyimide layer and thermoplastic polyimide layers provided on respective surfaces of the non-thermoplastic polyimide layer, wherein: among the polyamic acid solutions, a polyamic acid solution A for forming a thermoplastic polyimide layer to be in no direct contact with the support does not contain a chemical dehydrating agent or an imidization catalyst, a polyamic acid solution B for forming a thermoplastic polyimide layer to be in direct contact with the support contains an/the imidization catalyst, and a polyamic acid solution for forming the non-thermoplastic polyimide layer contains a/the chemical dehydrating agent and an/the imidization catalyst; wherein the formula of the polyamic acid solution A and the formula of the polyamic acid solution B prior to addition of a/the imidization catalyst is the same; and wherein the difference in properties of the thermoplastic polyimide layer to be in no direct contact with the support and the properties of the thermoplastic polyimide layer to be in direct contact with the support are reduced as compared to a like construction where thermoplastic polyimide layers are prepared from polyamic acid solutions having the same amount of chemical dehydrating agent and imidization catalyst.