Stabilized polyamide

Abstract

An article may include a polyamide composition comprising at least one modified polyamide produced by polymerizing polyamide precursors in a polymerization reactor to form a polyamide and adding, before, during, or at the end of polymerization, a polyhydric alcohol comprising at least three hydroxyl groups to the precursors and/or polyamide in the polymerization reactor.

1 - 13 . (canceled) 
     
     
         14 . An article comprising a polyamide composition comprising at least one modified polyamide produced by polymerizing polyamide precursors in a polymerization reactor to form a polyamide and adding, before, during, or at the end of polymerization, a polyhydric alcohol comprising at least three hydroxyl groups to the precursors and/or polyamide in the polymerization reactor. 
     
     
         15 . The article of  claim 14 , wherein the article is a radiator tank, a transfer pipe, a thermostatic tank, a degassing tank, a radiator, a turbo pipe, an air/air exchanger, an air inlet or outlet box of a turbo cooler, an air intake collector and the associated pipework, an article of the exhaust gas recycling circuit, a catalytic converter, a part of the engine-fan group, an intermediate cooler, a cylinder head cover, an oil sump, an oil filtration unit, a distribution sump, or oil-transporting assembly pipework. 
     
     
         16 . (canceled) 
     
     
         17 . A polyamide composition, comprising a modified polyamide that is produced by polymerizing polyamide precursors in a polymerization reactor to form a polyamide and adding, before, during, or at the end of polymerization, a polyhydric alcohol comprising at least three hydroxyl groups to the precursors and/or polyamide in the polymerization reactor. 
     
     
         18 . The article of  claim 14 , wherein the hydroxyl groups of the polyhydric alcohol are borne by aliphatic carbons of the polyhydric alcohol. 
     
     
         19 . The article of  claim 14 , wherein the amount of polyhydric alcohol added before, during, or at the end the polymerization, is from 0.05% to 20% by weight of polyhydric alcohol relative to the total weight of the polyamide and/or precursors thereof. 
     
     
         20 . The article of  claim 14 , wherein a mole proportion of the added polyhydric alcohol that is covalently bonded to the polyamide is between 10% and 100%. 
     
     
         21 . The article of  claim 14 , wherein the polyhydric alcohol is a compound of formula (I) represented by formula (I):
   R—(OH)n  (I)
   in which:
 n is between 3 and 8, 
 R is a substituted or unsubstituted aliphatic, cycloaliphatic or arylalkyl hydrocarbon-based radical, optionally comprising N, S, O and/or P heteroatoms. 
   
     
     
         22 . The article of  claim 14 , wherein the polyhydric alcohol is chosen from the group comprising: glycerol, trimethylolpropane, 2,3-bis(2′-hydroxyethyl)cyclohexan-1-ol, hexane-1,2,6-triol, 1,1,1-tris(hydroxymethyl)ethane, 3 -(2′-hydroxyethoxy)propane-1,2-diol, 3 -(2′-hydroxypropoxy)propane-1,2-diol, 2-(2′-hydroxyethoxy)hexane-1,2-diol, 6-(2′-hydroxypropoxy)hexane-1,2-diol, 1,1,1-tris [(2′-hydroxyethoxy)methyl]ethane, 1,1,1-tris [(2′-hydroxypropoxy)methyl]propane, 1,1,1-tris(4′-hydroxyphenyl)ethane, 1,1,1-tris(hydroxyphenyl)propane, 1,1,3 -tris(dihydroxy-3 -methylphenyl)propane, 1,1,4-tris(dihydroxyphenyl)butane, 1,1,5-tris(hydroxyphenyl)-3-methylpentane, di(trimethylolpropane), trimethylolpropane ethoxylate, or trimethylolpropane propoxylate; pentaerythritol, dipentaerythritol, tripentaerythritol, cyclodextrin, D-mannose, glucose, galactose, sucrose, fructose, xylose, arabinose, D-mannitol, D-sorbitol, D- or L-arabitol, xylitol, iditol, talitol, allitol, altritol, gulitol, erythritol, threitol and D-gulonic-y-lactone, and
 in particular from glycerol, trimethylolpropane, 2,3 -bis(2′-hydroxyethyl)cyclohexan-1-ol, hexane-1,2,6-triol, 1,1,1-tris(hydroxymethyl)ethane, 3 -(2′-hydroxyethoxy)propane-1,2-diol, 3-(2′-hydroxypropoxy)propane-1,2-diol, 2-(2′-hydroxyethoxy)hexane-1,2-diol, 6-(2′-hydroxypropoxy)hexane-1 ,2-diol, 1,1,1-tris [(2′-hydroxyethoxy)methyl]ethane, 1,1,1-tris [(2′-hydroxypropoxy)methyl]propane, di(trimethylolpropane), trimethylolpropane ethoxylate, or trimethylolpropane propoxylate; pentaerythritol, dipentaerythritol, tripentaerythritol, cyclodextrin, D-mannose, glucose, galactose, sucrose, fructose, xylose, arabinose, D-mannitol, D-sorbitol, D- or L-arabitol, xylitol, iditol, talitol, allitol, altritol, gulitol, erythritol, threitol and D-gulonic-y-lactone. 
 
     
     
         23 . The article of  claim 14 , wherein the polyhydric alcohol contains one or more amine functions. 
     
     
         24 . The article of  claim 14 , wherein the polyhydric alcohol is tris(hydroxymethyl)aminomethane and/or a salt thereof. 
     
     
         25 . The article of  claim 14 , wherein the polyamide is a semicrystalline polyamide with an apparent melt viscosity of the polyamide of between 0.5 and 1200 Pa.s, measured according to standard ISO 11443 at a shear rate of 1000 s −1  at a temperature equal to 20° C. above the melting point of the polyamide. 
     
     
         26 . The article of  claim 14 , wherein the polyhydric alcohol is added to the polyamide precursors in the polymerization reactor before or during polymerization of the precursors to form the polyamide. 
     
     
         27 . The article of  claim 26 , wherein as compared to a polyamide made by an analogous process wherein the polyhydric alcohol is added after polymerizing the polyamide precursors, the modified polyamide exhibits improved retention of tensile strength and of impact strength after ageing for 1000 hours at 170° C. 
     
     
         28 . The article of  claim 14 , wherein the polyhydric alcohol is added to the polyamide in the polymerization reactor at the end of the polymerization. 
     
     
         29 . The article of  claim 28 , wherein the polyhydric alcohol is added as a molten stream to the the polyamide in the polymerization reactor just before emptying the polymerization reactor. 
     
     
         30 . The composition of  claim 17 , wherein the hydroxyl groups of the polyhydric alcohol are borne by aliphatic carbons of the polyhydric alcohol. 
     
     
         31 . The composition of  claim 17 , wherein the amount of polyhydric alcohol added before, during, or at the end the polymerization, is from 0.05% to 20% by weight of polyhydric alcohol relative to the total weight of the polyamide and/or precursors thereof. 
     
     
         32 . The composition of  claim 17 , wherein a mole proportion of the added polyhydric alcohol that is covalently bonded to the polyamide is between 10% and 100%. 
     
     
         33 . The composition of  claim 17 , wherein the polyhydric alcohol is added to the polyamide precursors in the polymerization reactor before or during polymerization of the precursors to form the polyamide. 
     
     
         34 . The composition of  claim 17 , wherein as compared to a polyamide made by an analogous process wherein the polyhydric alcohol is added after polymerizing the polyamide precursors, the modified polyamide exhibits improved retention of tensile strength and of impact strength after ageing for 1000 hours at 170° C.