Use of a multi-layered structure for the manufacture of gas conducts, namely for methane

Abstract

The present invention relates to the use of a multi-layered structure for the manufacture of gas conducts, namely for methane. The multi-layered structure comprises, from the inside to the outside, the following successive layers: a layer containing at least one polyamide, wherein the polyamide is chosen from PA11, PA12 and an aliphatic polyamide obtained from condensation reaction of an aliphatic diamine having 6 to 18 carbon atoms and an aliphatic diacid having 9 to 18 carbon atoms; optionally, a binding 2 layer; and a layer 3 chosen from an EVOH layer, a layer formed of a mixture of polyamide and a polyolefin with a polyamide matrix, a layer of PA6,PA6-6, MXD.6 or MXD.10 and a layer of semi-aromatic copolyamide, the layer 3 being intended to be in contact with the transported gas.

1 . A multilayer gas duct structure comprising, from the outside towards the inside, the following successive layers:
 a layer 1 comprising at least one polyamide, the polyamide being chosen from PA-11, PA-12 and an aliphatic polyamide resulting from the condensation of an aliphatic diamine having from 6 to 18 carbon atoms and an aliphatic diacid having from 9 to 18 carbon atoms;   optionally, a tie layer 2; and   a layer 3 chosen from an EVOH layer, a layer formed from a blend of polyamide and a polyolefin with a polyamide matrix, a PA-6, PA-6,6, MXD-6 or MXD-10 layer and a semi-aromatic copolyamide layer,   the layer 3 being intended to be in contact with a transported gas.   
   
   
       2 . The multilayer gas duct structure according to  claim 1 , wherein the layer 1 further comprises at least one additive chosen from plasticizers, impact modifiers, functionalized or unfunctionalized polyolefins, dyes, pigments, brighteners, antioxidants and UV stabilizers. 
   
   
       3 . The multilayer gas duct structure according to  claim 1 , wherein the layer 3 is coated by the following successive layer(s):
 optionally, a tie layer 4; and   a polyamide-based layer 5, the layer 5 being in contact with the gas transported.   
   
   
       4 . The multilayer gas duct structure according to  claim 3 , wherein the layer 5 comprises at least one polyamide, the polyamide being chosen from PA-11, PA-12 and an aliphatic polyamide resulting from the condensation of an aliphatic diamine having from 6 to 18 carbon atoms and an aliphatic diacid having from 9 to 18 carbon atoms. 
   
   
       5 . The multilayer gas duct structure according to  claim 3 , wherein the layer 5 further comprises a functionalized polyolefin and/or an unfunctionalized polyolefin. 
   
   
       6 . The multilayer gas duct structure according to  claim 1 , wherein the multilayer structure in further comprises a protective layer 1′, placed on the layer 1. 
   
   
       7 . The multilayer gas duct structure according to  claim 1 , wherein the multilayer structure is a tube. 
   
   
       8 . The multilayer gas duct structure according to  claim 7 , wherein the tube is smooth. 
   
   
       9 . The multilayer gas duct structure according to  claim 7 , wherein the tube is ringed. 
   
   
       10 . The multilayer gas duct structure according to Clam 1, wherein said transported gas comprises methane.