Chemically resistant thermoplastic compositions

Abstract

Thermoplastic compositions are disclosed which include: a) a polyamide component comprising at least three amide monomer units and b) a stabilizer, wherein at least one of the at least three amide monomer units is an aliphatic amide monomer unit having a carbon to nitrogen ratio (C/N) equal to, or above 6.5, in that at least two of the at least three amide monomer units are semi-aromatic amide monomer units which polymerized provide at least one semi-crystalline semi-aromatic polyamide having a melting temperature of at least 290° C. as measured by DSC at a heating rate of 10° C./min according to standard ISO 11357-3 (2009), and in that the amount of aliphatic amide monomer unit is in the range from 20 to 60 wt. % relative to the total weight of the at least three amide monomer units in the polyamide components and the total amount of semi-aromatic amide monomer units is in the range from 40 to 80 wt. % relative to the total weight of the at least three amide monomer units in the polyamide components, and wherein the stabilizer is chosen from a copper-containing stabilizer, an iron-containing stabilizer and a stabilizer containing copper and iron.

1 . A thermoplastic composition comprising:
 a) a polyamide component comprising at least three amide monomer units, and   b) a stabilizer, wherein   at least one of the at least three amide monomer units is an aliphatic amide monomer unit having a carbon to nitrogen ratio (C/N) equal to, or above 6.5,   at least two of the at least three amide monomer units are semi-aromatic amide monomer units which polymerized provide at least one semi-crystalline semi-aromatic polyamide having a melting temperature of at least 290° C. as measured by DSC at a heating rate of 10° C./min according to standard ISO 11357-3 (2009),   the amount of aliphatic amide monomer unit is in the range from 20 to 60 wt. % relative to the total weight of the at least three amide monomer units in the polyamide component and the total amount of semi-aromatic amide monomer units is in the range from 40 to 80 wt. % relative to the total weight of the at least three amide monomer units in the polyamide component, and   the stabilizer is chosen from a copper-containing stabilizer, an iron-containing stabilizer and a stabilizer containing copper and iron.   
     
     
         2 . The thermoplastic composition according to  claim 1 , wherein the aliphatic amide monomer unit has a carbon to nitrogen ratio (C/N) in the range from 7 to 24. 
     
     
         3 . The thermoplastic composition according to  claim 1 , wherein the aliphatic amide monomer unit has a carbon to nitrogen ratio in the range from 7 to 11. 
     
     
         4 . The thermoplastic composition according to  claim 1 , wherein the aliphatic amide monomer unit has a carbon to nitrogen ratio in the range from 12 to 18. 
     
     
         5 . The thermoplastic composition according to  claim 1 , wherein the aliphatic amide monomer unit has a carbon to nitrogen ratio in the range from 19 to 24. 
     
     
         6 . The thermoplastic composition according to  claim 1 , wherein the amount of aliphatic amide monomer unit is in the range from 30 to 50 wt. % relative to the total amount of amide monomer units in the polyamide component and the amount of semi-aromatic amide monomer unit is in the range from 50 to 70 wt. % relative to the total amount of amide monomer units in the polyamide component. 
     
     
         7 . The thermoplastic composition according to  claim 1 , wherein the polyamide component a) is a blend consisting of:
 one aliphatic polyamide originating from an aliphatic amide monomer unit having a carbon to nitrogen ratio (C/N) equal to or above 7, and   one polyamide copolymer having a melting temperature of at least 290° C. as measured by DSC at a heating rate of 10° C./min according to standard ISO 11357-3 (2009), originating from at least two semi-aromatic amide monomer units.   
     
     
         8 . The thermoplastic composition according to  claim 1 , wherein the polyamide component a) is a blend consisting of:
 two aliphatic polyamides, one of which has a carbon to nitrogen ratio (C/N) equal to, or above 6 and one of which has a having a carbon to nitrogen ratio (C/N) equal to or above 7, and   one polyamide copolymer having a melting temperature of at least 290° C. as measured by DSC at a heating rate of 10° C./min according to standard ISO 11357-3 (2009), originating from at least two semi-aromatic amide monomer units.   
     
     
         9 . The thermoplastic composition according to  claim 1 , wherein the polyamide component a) is a blend consisting of:
 one aliphatic polyamide having a carbon to nitrogen ratio (C/N) equal to, or above 7 and   one polyamide copolymer having a melting temperature of at least 290° C. as measured by DSC at a heating rate of 10° C./min according to standard ISO 11357-3 (2009), originating from one aliphatic amide monomer unit having a carbon to nitrogen ratio (C/N) equal to or above 7 and from at least two semi-aromatic amide monomer units.   
     
     
         10 . The thermoplastic composition according to  claim 1 , wherein the semi-crystalline semi-aromatic amide monomer unit comprises terephtalic and/or isophtalic units. 
     
     
         11 . The thermoplastic composition according to  claim 1 , wherein the stabilizer b) consists of:
 i) 20-50 wt. % of an iron-containing component,   ii) 0-30 wt. % of at least one sodium salt, and   iii) 0-60 wt. % of a further additive, wherein   the wt. % is relative to the total weight of the stabilizer.   
     
     
         12 . The thermoplastic composition according to  claim 1 , wherein the stabilizer b) comprises elementary iron. 
     
     
         13 . The thermoplastic composition according to  claim 1 , wherein the stabilizer b) consists of elementary iron and optionally some iron oxide.