Multi-layered coextruded tube

Abstract

Multi-layered co-extruded tubes are provided that include an outer layer including a first semiaromatic semicrystalline polyamide having a melt temperature of about 240° C. to 280° C., and a thermal stabilizer; and an inner layer including a second semiaromatic semicrystalline polyamide having a glass transition equal to or greater than 100° C.

1 . A multi-layered co-extruded tube comprising
 A) an outer layer comprising a first polymer composition comprising a first semiaromatic semicrystalline polyamide and a copper thermal stabilizer, said first semiaromatic semicrystalline polyamide consisting essentially of   a) at least one repeat unit derived from monomers selected from one or more of the group consisting of:
 (j) aromatic dicarboxylic acid having 8 to 20 carbon atoms and at least one aliphatic diamine having 6 to 12 carbon atoms, and 
   b) at least one repeat unit derived from monomers selected from one or more of the group consisting of:
 (ii) aliphatic dicarboxylic acid having 10 to 14 carbon atoms and at least one aliphatic diamine having 6 to 12 carbon atoms, and 
 (iii) lactam and/or aminocarboxylic acid having 6 to 20 carbon atoms; and 
   B) an inner layer comprising a second polymer composition   comprising a second semiaromatic semicrystalline polyamide; wherein said first semiaromatic semicrystalline polyamide has a melt temperature of about 240° C. to 280° C.; and said second semiaromatic semicrystalline polyamide has a glass transition temperature equal to or greater than 100° C. as measured with dynamic mechanical analysis using ISO-6721-3 method   
     
     
         2 . The multi-layered co-extruded tube of  claim 1  wherein said second semiaromatic semicrystalline polyamide consists essentially of
 c) at least one repeat unit derived from monomers selected from the group consisting of
 (iv) aromatic dicarboxylic acid having 8 to 20 carbon atoms and at least one aliphatic diamine having 6 to 10 carbon atoms, and optionally 
   d) one or more repeat units derived from monomers selected from the group consisting of
 (v) aliphatic dicarboxylic acid having 6 to 14 carbon atoms and at least one aliphatic diamine having 6 to 10 carbon atoms, and 
 (vi) lactam and/or aminocarboxylic acid having 6 to 20 carbon atoms. 
   
     
     
         3 . The multi-layered co-extruded tube of  claim 1  wherein said second semiaromatic semicrystalline polyamide has a melting temperature greater than 270° C. 
     
     
         4 . The multi-layered co-extruded tube of  claim 1  wherein said second semiaromatic semicrystalline polyamide has a glass transition temperature equal to or greater than 125° C. 
     
     
         5 . The multi-layered tube of  claim 1  wherein said copper thermal stabilizer comprises about 0.1 to about 1.0 weight percent of a copper species selected from Cu(I), Cu(II), or a mixture thereof, based on the weight of the first polymer composition. 
     
     
         6 . The multi-layered tube of  claim 1  wherein said second polymer composition does not contain a Cu thermal stabilizer. 
     
     
         7 . The multi-layered tube of  claim 1  wherein said outer layer semiaromatic polyamide is selected from the group consisting of Group I polyamides having a terephthalic acid content of 60 to about 80 mol %, based on the total dicarboxylic acid content, selected from the group consisting of decamethylene terephthalamide/decamethylene decanediamide and decamethylene terephthalamide/decamethylene dodecanediamide; and Group II polyamides having a terephthalic acid content of 50 to about 80 mol %, based on the a total of acid repeat units, selected from the group consisting of nonamethylene terephthalamide/nonamethylene decanediamide, nonamethylene terephthalamide/nonamethylene dodecanediamide, nonamethylene terephthalamide/11-aminoundecanamide (PA 9T/11), nonamethylene terephthalamide/lauryl lactam, decamethylene terephthalamide/-aminoundecanamide (PA 10T/11), and decamethylene terephthalamide/lauryl lactam. 
     
     
         8 . The multi-layered co-extruded tube of  claim 2  wherein said second semiaromatic semicrystalline polyamide consists essentially of (c) repeat units (iv) wherein said at least one aliphatic diamine has 6 carbon atoms. 
     
     
         9 . The multi-layered tube of  claim 1  wherein said inner layer semiaromatic polyamide is selected from the group consisting of hexamethylene terephthalamide/2-methylpentamethylene terephthalamide copolyamide, hexamethylene terephthalamide/hexamethylene isophthalamide, hexamethylene adipamide/hexamethylene terephthalamide/hexamethylene isophthalamide copolyamide; hexamethylene terephthalamide/poly(caprolactam), poly(nonamethylene terephthalamide), and poly(decamethylene terephthalamide). 
     
     
         10 . The multi-layered tube of  claim 1  wherein the first polymer composition further comprises about 2 to about 50 weight percent of a polymeric toughener. 
     
     
         11 . The multi-layered tube of  claim 1  or  10  wherein the second polymer composition further comprises 2 to about 50 weight percent of a polymeric toughener.