WO2005121234A2 - Flame retarded polymer composition with improved thermal stability - Google Patents

Abstract

Flame retarded and thennally stabilized polymer composition comprising (i) thermoplastic polymer and (ii) flame retardant and stabilizer combined agent comprising as component (A), a flame retardant selected from the group consisting of a phosphinic salt of the formula (I), a diphosphinic salt of the formula (II), polymers of the formula (I), polymers of the formula (II) and mixtures thereof, characterized in that: R1, R2 are identical or different and are Cl-C-alkyl, linear or branched, or aryl; R3 is C1-Cl0-alkylene, linear or branched, C6­C10-arylene, alkylarylene or arylalkylene; M is Mg, Ca, Al, Sb, Sri, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K, or a protonated nitrogen base; m is 1 to 4; n is 1 to 4; x is I to 4, . as component B a flame retardant synergist selected from the group of nitrogen-containing synergists and phosphorus/nitrogen-containing synergists . as component (C), a thermal stabilizer selected from the group of basic or amphoteric oxide, hydroxide, carbonate, silicate, borate, stannate, mixed oxide/hydroxide, oxide/hydroxide/carbonate, hydroxide/silicate, hydroxide/borate, or a mixture thereof . optionally as component (D), a phosphonite . optionally as component (E), an ester or salt of montan wax acid, . optionally as component (F), a N,N'-bispiperidinyl-1,3-benzenedicarboxamide and/or N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzene­- dicarboxamide, said polymer composition being characterized in that the thermoplastic polymer (i) is a semi-aromatic polyamide comprising recurring units derived from a dicarboxylic acid component including at least one aliphatic dicarboxylic acid and a diamine component including at least one aromatic diamine. Shaped article comprising said composition.

Description

Flame retarded polymer composition with improved thermal stability

The invention relates to a thermally stable flame retarded polymer composition comprising a semi-aromatic polyamide derived from at least one aromatic diamine. The invention also relates to a shaped article made of said polymer composition. Semi-aromatic polyamides (like those derived from phthalic acids and aliphatic diamines, i.e. polyphthalamides, or those derived from aromatic diamines and aliphatic diacids) are polymers having excellent mechanical, physical and chemical properties which make them useful for a wide variety of different applications. For certain end-uses, it is desirable that compositions based on these semi- aromatic polyamides, notably those derived from aromatic diamines and aliphatic diacids, be flame retarded, so as to meet UL 94 V-0 standard for high degree of flame retardance. A method generally used to impart flame retardance to polymers involves incorporating halogenated flame retardant agents. However, especially in the case of the high melting semi-aromatic polyamides, halogenated flame retardants tend to thermally decompose at the molding temperature. The halogenated degradation products corrode the surfaces of the compounding extruder and impart poor surface appearance to the molded articles. In particular, prior art halogenated flame retarded compositions based on polyamide derived from aromatic diamines are rather unstable during melt processing, that resulting in degradation and/or decomposition problems like discoloration, out gassing, blooming at the surface of the molded article and molecular weight degradation of the polymer matrix. It would be highly desirable that such flame retarded compositions, in particular those based on polyamides derived from adipic acid and m- xylylenediamine (i.e. MXD6 polyamides), would not only comply with UL 94 V-0 standard, but also have excellent thermal stability and mold ability. These flame retarded and thermal stabilized MXD6 compositions, if available, would be useful for a wide variety of different applications like, for instance, the molding electrical and electronic parts. Several halogen free flame retardants and halogen free flame retarded polymer compositions are known in the art. For instance US 3,900,444 discloses flame resistant thermoplastic polyesters containing halogen free flame retardants based on alkali metal phosphinates. The use of metal phosphinates as halogen free flame retardants for, above all, amorphous polyamides is disclosed by US 4,036,811. Synergistic combinations of metal phosphinates with certain nitrogen-containing compounds is disclosed by US 6,365,071. These synergistic combinations are generally more effective than metal phosphinates alone in respect of many thermoplastic polymers (like for example polyolefins, polystyrene, halogenated polymers, polyacetals, polycarbonates, polysulfones, polyetherketones, polyamides, polyesters), preferably engineering plastics and especially polyesters. WO0066658 describes the utilization of carbodiimides, isocyanates and isocyanurates for the purpose of stabilizing polymer molding compositions containing phosphorous-based flame retardants. However, as pointed out by US 2004/0227130, when halogen free phosphorus-containing flame retardants are used specifically in combination with polyamides, the action of the stabilizers described hitherto has proven to be insufficient, especially for suppressing effects arising during melt processing, such as discoloration and molecular-weight degradation. If halogen free flame retarded polyamide compositions wherein the polyamide is an aliphatic polyamide or a polyphthalamide and the flame retardant is a metal phosphinate, alone or in combination with other synergists, are relatively well described in the prior art (US 2005/014874), the same cannot be said for those halogen free flame retarded polyamide compositions wherein the polyamide is a semi-aromatic polyamide derived from at least one aromatic diamine, like for example MXD6 polyamides. US 6,255,371 and US 2005/014874 disclose halogen free flame retarded compositions based on thermoplastic polymers, wherein the thermoplastic polymer can be MXD6 polyamides or polyamides including an aromatic diamine like xylylendiamine and wherein the flame retardant is a metal phosphinate in combination, optionally or not, with a nitrogen synergist. However, prior art is silent on the thermal stability of such polymer compositions as well as on the degradation problems expected to arise during their melt processing. On the other hand, flame retardant and stabilizer combined agents have been described by US 2004/ 0227130 for a wide variety of different thermoplastic polymers, but these agents are reported to be effective especially for polyesters and aliphatic polyamides like nylon-6 and nylon 6-6. From the foregoing discussion it results that further research is needed in this area, especially in order to understand which is the flame retardant behavior, the thermal stability and the mold ability of halogen free flame retarded polyamide compositions based on aromatic polyamides derived from at least one aromatic diamine. In particular, it is an objective of the invention to provide a flame retarded polyamide composition based on a semi-aromatic polyamide comprising recurring units derived from a dicarboxylic acid component including at least one aliphatic dicarboxylic acid and a diamine component including at least one - aromatic -diamine, wherein said composition, besides complying withUL 94 V-0 standard for high degree of flame retardance, would also have excellent thermal stability so as to be molded without encountering any of the degradation and/or discoloration problems previously mentioned. The invention therefore provides a flame retarded and thermally stabilized polymer composition comprising (i) a thermoplastic polymer and (ii) a flame retardant and stabilizer combined agent comprising ■ as component (A), a flame retardant selected from the group consisting of a phosphinic salt of the formula (I), a diphosphinic salt of the formula (II), polymers of the formula (I), polymers of the formula (LI) and mixtures thereof,

characterized in that: R¹, R² are identical or different and are Cl-C-alkyl, linear or branched, or aryl; R³ is Cl-ClO-alkylene, linear or branched, C6- ClO-arylene, alkylarylene or arylalkylene; M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K, or a protonated nitrogen base; m is 1 to 4; n is 1 to 4; x is 1 to 4, - as component (B), a flame retardant synergist selected from the group of nitrogen-containing synergists and phosphorus/nitrogen-containing synergists

■ as component (C), a thermal stabilizer selected from the group of basic or amphoteric oxide, hydroxide, carbonate, silicate, borate, stannate, mixed oxide/hydroxide, xide/hydroxide/carbonate, hydroxide/silicate, hydroxide/borate, or a mixture thereof

« optionally as component (D), a phosphonite of the structure

R-[P(OR₁)₂]_m (I) characterized in that R is a mono- or polyvalent aliphatic, aromatic, or heteroaromatic organic radical and Ri is a compound of the structure (II) ry. iβ)

or the two radicals Rl form a bridging group of the structure (III)

characterized in that: A is a direct bond, O, S, Cl-18-alkylene (linear or branched), or Cl-18-alkylidene (linear or branched); R₂, independently of one another, are Cl-2-alkyl (linear or branched), Cl-12-alkoxy, or C5-12- cycloalkyl; and n is from 0 to 5, and m is from 1 to 4, ■ optionally as component (E), an ester or salt of montan wax acid, ■ optionally as component (F), aN,N'-bispiperidinyl-l,3-benzenedicarboxamide and/or N,N^,-bis(2,2,6,6-tetramethyl-4-piperidinyl)-l,3-benzenedicarboxamide, said polymer composition being characterized in that the thermoplastic polymer (i) is a semi-aromatic polyamide comprising recurring units derived from a dicarboxylic acid component including at least one aliphatic dicarboxylic acid and a diamine component including at least one aromatic diamine. The inventive aromatic polyamide composition provides reduced discoloration during processing in the melt, reduced degradation together with full retention of flame retardancy. M is preferably calcium, aluminum or zinc. The protonated nitrogen bases are preferably the protonated bases of ammonia, melamine, triethanolamine, in particular NH₄ ⁺. R¹ and R², identical or different, are preferably Cl-C6-alkyl, linear or branched, and/or phenyl. R and R , identical or different, are particularly preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl and/or phenyl.

R³ is preferably methylene, ethylene, n-propylene, isopropylene, n-butylene, tert- butylene, n-pentylene, n-octylene, or n-dodecylene. Another preferred meaning of R³ is phenylene or naphthylene. Suitable phosphinates have been described in US 6,365,071 expressly incorporated herein by way of reference. Particularly preferred phosphinates are aluminum phosphinates, calcium phosphinates, and zinc phosphinates. Synergistic combinations of the specified phosphinates with nitrogen- containing compounds which have more effective action as flame retardants than the phosphinates alone in very many polymers (US 6,365,071, US 6,207,736, US 6,509,401) are also in accordance with the invention. The flame-retardant action of the phosphinates may be improved via combination with other flame retardants, preferably nitrogen-containing synergists, or phosphorus/nitrogen flame retardants. The nitrogen-containing synergist of component (B) is of the formulae (III) to (VIII), or a mixture thereof

where: R⁵ to R⁷ are hydrogen, Cl-C8-alkyl, C5-C16-cycloalkyl or - alkylcycloalkyl, optionally substituted with a hydroxy or a Cl-C4-hydroxyalkyl function, C2-C8-alkenyl, Cl-C8-alkoxy, -acyl, -acyloxy, C6-C12-aryl or - arylalkyl, -OR⁸, or -N(R⁸)R⁹, or a N-alicyclic or N-aromatic system; R⁸ is hydrogen, Cl-C8-alkyl, C5-C16-cycloalkyl or -alkylcycloalkyl, optionally substituted with a hydroxy or a Cl-C4-hydroxyalkyl function, C2-C8-alkenyl, Cl-C8-alkoxy, -acyl, -acyloxy, or C6-C12-aryl or -arylalkyl; R⁹ to R¹³ are the same as the groups for R⁸, or else -O-R⁸; m and n independently of one another, are 1, 2, 3, or 4; X is an acid which forms adducts with triazine compounds (III), or an oligomeric ester of tris(hydroxyethyl) isocyanurate with aromatic polycarboxylic acids. The nitrogen-containing synergists preferably comprise benzoguanamine, tris(hydroxyethyl) isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide, guanidine, carbodiimides. The nitrogen-containing synergists preferably comprise condensation products of melamine. By way of example, condensation products of melamine are melem , melam, or melon, or compounds of this type with a higher condensation level, or else a mixture of the same, and, by way of example, may be prepared by the process described in US 5,985,960. The phosphorus/mtrogen-containing synergists may comprise reaction products of melamine with phosphoric acid or with condensed phosphoric acids, or comprise reaction products of condensation products of melamine with phosphoric acid or. condensed phosphoric acids, or else comprise a mixture of the specified products. The reaction products with phosphoric acid or with condensed phosphoric acids are compounds which arise via reaction of melamine or of the condensed melamine compounds, such as melam, melem, or melon etc., with phosphoric acid. By way of example, these are dimelamine phosphate, dimelamine pyrophosphate, melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melam polyphosphate, melon polyphosphate, and melem polyphosphate, and mixed polysalts, e.g. those described in US 6,121,445 and US 6,136,973. The phosphorus/nitrogen-containing synergist may also be ammonium hydrogenphosphate, ammonium dihydrogenphosphate, or ammonium polyphosphate. Preferably the phosphorus/nitrogen-containing synergist of component (B) is at least one nitrogen containing phosphate selected from the group of melamine polyphosphate, ammonium hydrogenophosphate, ammonium dihydrogenophosphate, and ammonium polyphosphate. Additives may be added to the phosphinates alone or in combination with phosphorus/nitrogen flame retardants, examples of these additives being: 1. Antioxidants

1.1 Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylph- enol, 2- butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl- 4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4- methylphenol, 2-α-mefhylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl- 4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4- methoxymethylphenol, 2,6-dinonyl-4-methylphenol, 2,4-dimethyl-6-(l '- methylundec- -yl)phenol, 2,4-dimethyl-6-( -methylheptadec-r-yl)phenol, 2,4-dimethyl-6-( -methyltridec-r-yl)phenol and mixtures thereof.

1.2 Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert- butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl- 6-ethylphenol, 2,6-didodecylthiomethyl-4-nonylpheno- 1.

1.3 Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl- 4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert- amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert- butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4- hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, to (3,5-di-tert- butyl-4-hydroxyphenyl) adipate.

1.4 Tocopherols, for example α-tocopherol, /3-tocopherol, γ-tocopherol, δ- tocopherol, and mixtures thereof (vitamin E). 1.5 Hydroxylated thiodiphenyl ethers, for example 2,2'-thiobis(6-tert-butyl-4- methyrphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-3 - methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis(3 ,6-di- sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxyphenyl) disulfide. 1.6 Alkylidenebisphenols, for example 2,2'-methylenebis(6-tert-buty- 1-4- methylphenol), 2,2'-methylenebis(6-tert-butyl-4-ethylρhenol), 2,2'- methylenebis[4-methyl-6-(o;-methylcyclohexyl)phenol], 2,2'- methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl- -4- methylphenol), 2,2'-methylenebis(4,6-di-tert-butylphenol), 2,2'- ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(6-tert-bu- tyl-4- isobutylphenol), 2,2'-methylenebis[6-(θ!-methylbenzyl)-4-nonylphenol], 2,2'-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol- ], 4,4'- methylenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(6-tert-bu- tyl-2- methylphenol), 1 , 1 -bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6- bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, l,l,3-tris(5- tert-butyl-4-hydroxy-2-methylphenyl)butane, 1 , 1 -bis(5 -tert-butyl-4- hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol to [3₅3-bis(3'-tert-butyl-4'-hydroxyphenyl) butyrate], to (3-tert-butyl-4- hydroxy-5-methylphenyl)dicyclopentadiene, to [2-(3'-tert-butyl-2'-hydroxy- 5'-methylbenzyl)-6-tert-butyl-4-methylphenyl- ] terephthalate, 1,1 -bis (3,5- dimethyl-2-hydroxyphenyι)butane, 2,2-bis(3,5-di-tert-butyl-4- hydroxyphenyl) propane, 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4- n-dodecylmercaptobutane, 1 , 1 ,5,5-tetra(5-tert-butyl-4-hydroxy-2- methylphenyl)pentane.

1.7 O-, N- and S-benzyl compounds, for example 3,5,3',5'-tetra-tert-butyl-4,4'- dihydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzylmercapto acetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, (4-tert-butyl-3- hydroxy-2,6-dimethylbenzyl) dithioterephthalate, (3 ,5-di-tert-butyl-4- hydroxybenzyl) sulfide, isooctyl 3,5-di-tert-butyl-4- hydroxybenzylmercaptoacetate.

1.8 Hydroxybenzylated malonates, for example dioctadecyl 2,2-bis(3,5-di-tert- butyl-2-hydroxybenzyl)malonate, dioctadecyl 2-(3-tert-butyl-4-hydroxy-5- methylbenzyl)malonate, didodecyl mercaptoethyl-2,2-bis(3,5-di-tert-butyl- 4-hydroxybenzyl)malonate, di-[4-(l,l,3,3-tetramethylbutyl)phenyl] 2,2- bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

1.9 Aromatic hydroxybenzyl compounds, for example l,3,5-tris(3,5-di-tert- butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1 ,4-bis(3,5-di-tert-butyl-4- hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-bιxtyl-4- hydroxybenzyl)phenol. l.lOTriazine compounds, for example 2,4-bisoctylmercapto-6-(3,5-di-tert-butyl- 4-hydroxyanilino)- 1 ,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl- 4-hydroxyanilino)-l,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl- 4-hydroxyphenoxy)- 1 ,3,5-triazine, 2,4,6-tris(3,5-di-tert-butyl-4- hydroxyphenoxy)-l,2,3-triazine, l,3,5-tris(3,5-di-tert-butyl-4- hydroxybenzyl) isocyanurate, l,3,5-tris(4-tert-butyl-3-hydroxy-2,6- dimethylbenzyl) isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4- hydroxyphenylethyl)-l,3, 5-triazine, l,3,5-tris(3,5-di-tert-butyl-4- , hydroxyphenylpropionyl)hexahydro-l,3,5-triazine, l,3,5-tris(3,5- dicyclohexyl-4-hydroxybenzyl) isocyanurate. l.H Benzylphosphonates, for example dimethyl 2,5-di-tert-butyl-4- hydroxybenzylphosphonate, diethyl 3,5-di-tert-butyl-4- hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert-butyl-4- hydroxybenzylphosphonate, dioctadecyl 5-tert-butyl-4-hydroxy-3- methylbenzylphosphonate, the Ca salt of the monoethyl ester of 3,5-di-tert- butyl-4-hydroxybenzylphosphonic acid. 1.12 Acylaminophenols, for example 4-hydroxylauranilide, 4- hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate. 1.13 Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'- bis(hydroxyethyl)oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-l-phospha- 2,6,7-trioxabicyclo[2.2.2]octane. 1.14Esters of /3-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2- propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydiOxyethyl) isocyanurate, N,N'- bis(hydroxyethyl)oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-l-phospha- 2,6,7-trioxabicyclo[2.2.2]octane. 1.15 Esters of /3-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'- bis(hydroxyethyl)oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-l-phospha- 2,6,7-trioxabicyclo[2.2.2]octane. 1.16Esters of 3,5-di-tert-butyl-4-hydroxyphenylacetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6- hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'- bis(hydroxyethyl)oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-l-phospha- 2,6,7-trioxabicyclo[2.2.2]octane. 1.17 Amides of _/S-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, e.g. N,N'- bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamefhyl- enediamine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethyle- nediamine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine. 2. UV absorbers and Light Stabilizers

2.1 2-(2'-Hydroxyphenyl)benzotriazoles, for example 2-(2'-hydroxy-5'- methylphenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hy- droxyphenyl)- benzotriazole, 2-(5'-tert-butyl-2^,-hydroxyphenyl)benzotriazol- e, 2-(2'- hydroxy-5'-(l, 1 ,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert- butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'-tert-butyl-2'-hydroxy- 5'-methylphenyl)-5-chlorobenzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'- hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis(α,Q!- dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, a mixture of 2-(3 '-tert- butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5- chlorobenzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]- 2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2- methoxycarbonyl-ethyl)phenyl)-5-chlorobenzotriazole, 2-(3'-tert-butyl-2'- hydroxy-5 '-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3 '-tert-butyl- 2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert- butyl-5'-[2-(2-ethyl- hexyloxy)carbonylethyl]-2'- hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2 '-hydroxy-5 '- methylphenyl)benzotriazole, and 2-(3'-tert-butyl-2'-hydroxy-5'-(2- isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2'-methylenebis[4- (1,1 ,3,3-tetramethylbutyl)-6-benzotriazol-2-ylphenol] ; the transesterification product of 2-[3'-tert-butyl-5'-(2-methoxyc- arbonylethyl)-2'- hydroxyphenyl]benzotriazole with polyethylene glycol 300; [R-CH₂CH₂- COO(CH₂)₃]₂-, where R=3'-tert-butyl-4*-hydroxy-5'-2H-benzotriazol-2- ylphenyl.

2.2 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4- octoxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'- hydroxy-4,4'-dimethoxy derivative.

2.3 Esters of substituted or unsubstituted benzoic acids, for example 4-tert- butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoylresorcinol, to (4-tert-butylbenzoyl)resorcinol, benzoyhesorcinol, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5- di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4- hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4- hydroxybenzoate. 2.4 Acrylates, for example ethyl α-cyano-/3,|3-diphenylacrylate or isooctyl - cyano-/3,/5-diphenylacrylate, methyl α-carbomethoxycinnamate, methyl - cyano- -methyl-p-methoxycinnamate or butyl α-cyano-/3-methyl-p- methoxycinnamate, methyl α-carbomethoxy-p-methoxycinnamate and N- (3-carbomethoxy-jS-cyanovinyl)-2-methylindoline.

2.5 Nickel compounds, for example nickel complexes of 2,2'-thiobis[4-(l, 1,3,3- tetramethylbutyl)phenol], such as the 1 :1 or 1 :2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyl- diethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters, such as of the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert- butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2- hydroxy-4-methylphenyl undecyl ketoxime, nickel complexes of 1 -phenyl- 4-lauroyl-5-hydroxypyrazole, with or without additional ligands.

2.6 Sterically hindered amines, for example to (2,2,6,6-tetramethylpiperidyl) sebacate, to (2,2,6,6-tetramethylpiperidyl- ) succinate, to (1,2,2,6,6- pentamethylpiperidinyl) sebacate, to (1,2,2,6,6-pentamethylpiperidyl) n- butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1- hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,N'-bis(2,2,6,6-tetramethy- 1-4- piperidyl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-l,3,- 5- s-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1 ,2,3 ,4-butanetetraoate, 1 , l'-(l ,2- ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6- tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethyl- piperidine, to (1,2,2,6,6-pentamethylpiperidyl) 2-n-butyl-2-(2-hydroxy-3,5- -di-tert- butylbenzyl)malonate, 3 -n-octyl-7,7,9,9-tetramethyl- 1 ,3 ,8-triazas- piro [4.5] decane-2,4-dione, to (l-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate, to (l-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, the condensate of N,N'- bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4- morpholino-2,6-dichloro- 1 ,3 ,5-triazine, the condensate of 2-chloro-4,6-di- (4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-l,3, 5-triazine and l,2-bis(3- aminopropylamino)ethane, the condensate of 2-chloro-4,6-di(4-n- butylamino- 1 ,2,2,6,6-pentamethylpiperidyl)- 1 ,3 ,5-triazine and 1 ,2-bis(3- aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-l,3,8- triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-l-(2,2,6,6-tetramethyl-4- piperidyl)pyrrolidine-2,5-dione, 3-dodecyl-l-(l,2,2,6,6-pentamethyl-4- piperidyl)pyrrolidine-2,5-dione.

2.7 Oxalamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butyloxanilide, 2,2'-didodecyloxy-5,5'-di-tert- butyloxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'-bis(3-dimethylamino- propyl)oxalamide, 2-ethoxy-5-tert-butyl-2'-ethyloxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butyloxanilide and mixtures of o- and p- methoxy-disubstituted and of o- and p-ethoxy-disubstituted oxanilides.

2.8 2-(2-Hydroxyphenyl)-l,3,5-triazines, such as 2,4,6-tris(2-hydroxy-4- octyloxyphenyl)-l,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6- bis(2,4-dimethylphenyl)- 1 ,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6- bis(2,4-dimethylphenyl)- 1 ,3,5-triazine, 2,4-bis(2-hydroxy-4- propyloxyphenyl)-6-(2,4-dimethylphenyl)-l,3,5-triazine, 2-(2-hydroxy-4- octyloxyphenyl)-4,6-bis(4-methylphenyl)-l,3,5-triazine, 2-(2-hydroxy-4- dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-l,3,5-triazine, 2-[2- hydroxy-4-(2-hydroxy-3 -butyloxypropyloxy)phenyl] -4,6-bis(2,4- dimethylphenyl)-l,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3- octyloxypropyloxy)- phenyl]-4,6-bis(2,4-dimethylphenyl)-l,3,5-triazine.

3. Metal deactivators, for example, N,N'-diphenyloxalamide, N-salicylal-N'- salicyloylhydrazine, N,N'-bis(salicyloyl)hydrazine, N,N'-bis(3,5-di-tert- butyl-4-hydroxyphenylpropionyl)hydrazine, 3-salicyloylamino-l,2,4- triazole, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyloyl)oxalyl dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide.

4. Phosphites and phosphonites, for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, isodecyloxy pentaerythritol diphosphite, (2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, (2,4,6-tri-tert-butylphenyl) pentaerytliritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12- H-dibenzo [d,g] - 1 ,3 ,2-dioxaphosphocin, 6-fluoro-2,4,8, 10-tetra-tert-butyl- 1 - 2-methyldibenzo[d,g]-l ,3,2-dioxaphosphocin, (2,4-di-tert-butyl-6-methyl- phenyl) methyl phosphite, (2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite.

5. Peroxide degraders, e.g. esters of jS-thiodipropionic acid, for example the lauryl, stearyl, myristyl, or tridecyl esters, mercaptobenzimidazole, the zinc salt of 2-mercaptobenzimidazole, zinc dibutyldithiocarbamate, dioctadecyl disulfide, pentaerytliritol tetrakis(/3-dodecylmercapto)propionate.

6. Polyamide stabilizers, e.g. copper salts in combination with iodides and/or phosphorus compounds; salts of divalent manganese.

7. Basic costabilizers, e.g. melamme, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, the alkali metal and alkaline earth metal salts of higher fatty acids, examples being Ca stearate, Zn stearate, Mg behenate, Mg stearate, Na ricinoleate, K palmitate, antimony pyrocatecholate, or tin pyrocatecholate. 8. Nucleating agents, e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid. 9. Fillers and reinforcing agents, e.g. calcium carbonate, silicates, glass fibers, asbestos, talc, kaolin, mica, barium sulfate, metal oxides, and metal hydroxides, carbon black, graphite. 10. Other additives, e.g. plasticizers, expandable graphite, lubricants, emulsifiers, pigments, optical brighteners, flame retardants, antistatic agents, blowing agents. The thermal stabilizer corresponding to component (C) is for example: magnesium oxide, calcium oxide, aluminum oxide, zinc oxide, manganese oxide, tin oxide, aluminum hydroxide, boehmite, magnesium hydroxide, hydrotalcite, hydrocalumite, calcium hydroxide, zinc hydroxide, tin oxide hydrate, manganese hydroxide, zinc borate, basic zinc silicate, zinc stannate, and/or zinc hydroxide. Preferably, the thermal stabilizer is zinc borate, magnesium hydroxide, zinc hydroxide, dihydrotalcite, and/or boehmite. More preferably, the thermal stabilizer is zinc borate. Zinc borate useful for the present invention is preferably anhydrous zinc borate with less than 0.2 wt. % of water (as described in US 5,204,400) and, more preferably, with no measurable water content like XPI-187 zinc borate from U.S. Borax. Phosphonites of the structure

are suitable as component D, where

R is a mono- or polyvalent aliphatic, aromatic, or heteroaromatic organic radical, and R_: is a compound of the structure (II)

or the two radicals Rl form a bridging group of the structure (III)

where A is a direct bond, O, S, Cl-18-alkylene (linear or branched), or Cl-18- alkylidene (linear or branched), where R₂ independently of one another, are Cl-

2-alkyl (linear or branched), Cl-12-alkoxy, or C5-12-cycloalkyl, and n is from 0

The preferred radicals are

R C4-18-alkyl (linear or branched), C4-18-alkylene (linear or branched), C5-12- cycloalkyl, C5-12-cycloalkylene, C6-24-aryl or -heteroaryl, C6-24-arylene or heteroarylene, which may also have further substitution; R_t a group of the structure (II) or (III), where R₂, independently of one another, are Cl-8-alkyl (linear or branched), Cl-

8-alkoxy, cyclohexyl;

A is a direct bond, O, Cl-8-alkylene (linear or branched), Cl-8-alkylidene (linear or branched), and n is from 0 to 3, and m is from 1 to 3. Particularly preferred radicals are

R cyclohexyl, phenyl, phenylene, biphenyl radicals,

Ri a group of the structure (II) or (III), where

R₂, independently of one another, are Cl-8-alkyl (linear or branched), Cl-8- alkoxy, cyclohexyl A is a direct bond, O, Cl-6-alkylidene (linear or branched), and n is from 1 to 3, and m is 1 or 2. Mixtures of compounds in accordance with the preceding claims in combination with phosphites of the formula (IV) are also claimed, where R_! is as defined above P(ORι)₃ (TV). Particular preference is given to compounds which, on the basis of the preceding claims, are prepared via a Friedel-Crafts reaction of an aromatic or heteroaromatic system, such as benzene, biphenyl, or diphenyl ether, with phosphorus trihalides, preferably phosphorus trichloride, in the presence of a Friedel-Crafts catalyst, such as aluminum chloride, zinc chloride, iron chloride, etc., and a subsequent reaction with the phenols underlying the structures (II) and (III). Mixtures with phosphites produced in the specified reaction sequence from excess phosphorus trihalide and from the phenols described above are expressly also covered by the invention. Among this group of compounds, preference is in turn given to the structures (V) and (VI) below:

where n may be 0 or 1, and where these mixtures may also optionally comprise proportions of the compound (VII) or (VIII):

Esters or salts of long-chain aliphatic carboxylic acids (fatty acids), these typically having chain lengths of from C14 to C40, are suitable as component (E). The esters comprise reaction products of the specified carboxylic acids with familiar polyhydric alcohols, e.g. ethylene glycol, glycerol, trimethylolpropane, or pentaerythritol. The alkali metal or alkaline earth metal salts, or aluminum salts and zinc salts of the specified carboxylic acids are in particular used. Component (E) preferably comprises esters or salts of stearic acid, e.g. glycerol monostearate or calcium stearate. Component (E) preferably comprises reaction products of montan wax acids with ethylene glycol. The reaction products preferably comprise a mixture composed of the mono- and di- (ethylene glycol) esters of montan wax acid, montan wax acids, and ethylene glycol. Component (E) -preferably comprises reaction products of montan wax acids with a calcium salt. The reaction products particularly preferably comprise a mixture composed of the mono- and di(l,3-butanediol) esters of montan wax acid, montan wax acids, 1,3-butanediol, calcium montanate, and the calcium salt. Carboxylic (ester) amides are suitable as component (F). Component (F) preferably comprises a derivative of an aromatic di- or tricarboxylic (ester) amide. The derivative preferably comprises N,N'-bispiperidmyl-l,3-benzene- dicarboxamide. The derivative particularly preferably comprises N,N'-bis(2,2,6,6-tetra- methyl-4-piperdinyl)- 1 ,3 -benzenedicarboxamide. The quantitative proportions of components (A), (B), and (C) in the flame retardant and stabilizer combined agent depend in essence on the intended application sector, and may vary within wide limits. Depending on the application sector, the flame retardant and stabilizer combined comprises from 25 to 99.9% by weight of component (A), from 0 to 75% by weight of component (B), and from 0.1 to 50% by weight of component (C), from 0 to 5% by weight of component (D), from 0 to 5% by weight of component (E), and from 0.1 to 5% by weight of component (F). The flame retardant and stabilizer combined agent preferably comprises from 50 to 90% by weight of component (A), from 0 to 50%) by weight of component (B), from 1 to 20% by weight of component (C), from 0 to 5% by weight of component (D), from 0 to 5% by weight of component (E), and from 0.1 to 5% by weight of component (F). The flame retardant and stabilizer combined agent particularly preferably comprises from 50 to 80%> by weight of component (A), from 20 to 50% by weight of component (B), and from 2 to 20% by weight of component (C), from 0 to 3% by weight of component (D), from 0 to 3% by weight of component (E), and from 0.1 to 4% by weight of component (F). The inventive flame retardant and stabilizer combined may also comprise carbodiimides. The aliphatic dicarboxylic acid used for the preparation of the semi- aromatic polyamide is advantageously chosen from the group of the linear aliphatic α,ω -dicarboxylic acids and alicyclic dicarboxylic acids. It is possible to use a single acid or a mixture of acids. The aliphatic dicarboxylic acid is preferably a linear aliphatic acid containing from 4 to 12 carbon atoms and, more preferably it is adipic acid. The dicarboxylic acid component may further comprise dicarboxylic acids other than aliphatic dicarboxylic acids, for example aromatic dicarboxylic acids. The aromatic diamine is advantageously meta-xylylenediamine, para- xylylenediamine or a mixture of these. Preferably the aromatic diamine is m- xylylenediamine. The diamine component may further comprise at least one diamine chosen from the group of linear aliphatic diamines, alicyclic diamines, aromatic diamines other than xylylenediamines. If necessary, the semi-aromatic polyamide may further comprise copolymerized recurring units derived from at least one -ω aminocarboxylic acid and/or at least one lactam. Preferably the semi-aromatic polyamide comprises recurring units derived from at least one linear aliphatic dicarboxylic acid containing from 4 to 12 carbon atoms and at least one xylylenediamine. More preferably, the semi-aromatic polyamide comprises recurring units derived from adipic acid and m-xylylenediamine. Still more preferably, the semi-aromatic polyamide consists of recurring units derived from adipic acid and m-xylylenediamine. Semi-aromatic polyamides derived from adipic acid and m- xylylenediamine are commercially available under the trade name LXEF^® polyamide from SOLVAY ADVANCED POLYMERS L.L.C.. The flame retarded and thermally stabilized polymer composition as above described may further comprise at least one optional additional component selected from the group of fillers, reinforcing agents, fiberglass, lubricant agents, pigments, polymers other than the semi-aromatic polyamide, antioxidants, UV absorbers and light stabilizers, metal deactivators, phosphites and phosphonites, peroxide degraders, polyamide stabilizers, basic costabilizers, nucleating agents, and carbodiimmides. Preferably, the optional additional component is selected from the group of fiberglass, lubricant agents, aliphatic polyamides and nucleating agents. The amount of flame retardant and stabilizer combined agent comprised in the composition according to the invention is advantageously of at least 1 wt. %, preferably of at least 2 wt.% and more preferably of at least 5 wt. % based on the total weight of the composition. Besides, this amount is advantageously of at most 30 wt. %, preferably of at most 20 wt. % and more preferably of at most 15 wt. %. In certain preferred embodiments of the present invention, the flame retarded and thermally stabilized composition comprises fiberglass as reinforcing agent. In these embodiments, fiberglass is advantageously present in an amount of at least 30 wt. %, preferably of at least 45 wt. % and more preferably of at least 50 wt. % based on the total weight of the composition. Besides, fiberglass is advantageously present in an amount of at most 90 wt. %, preferably of at most 80 wt. % and more preferably of at most 70 wt. % based on the total weight of the composition. The components of the flame retardant and stabilizer combined agent along with and the optional additional components may be incorporated into the aromatic polyamide by a variety of different methods and procedural steps. For example, it is possible to incorporate the above mentioned components by mixing them into the polymer at an early stage: at the start or at the end of the polymerization/polycondensation of the polyamide, or in a subsequent compounding process. There are also processes in which the components of the flame retardant and stabilizer combined agent are not added until later. A possibility consists in dry mixing the different components of the composition in a drum before blending them by extrusion. Eventually the components of the flame retardant and stabilizer combined agent may be applied onto the polymer pellets, which may have retained heat from a drying process. The present invention also relates a shaped article comprising the flame retarded and thermally stabilized polymer composition as previously described. The shaped article according to the invention is advantageously an electric or an electronic part. Examples

■ Components used for Examples 1-3 (1) LXEF ^® 6002, nucleated MXD6 polyamide derived from m-xylylene diamme and adipic acid. (2) Exolit ^® OP 1312 (Clariant), flame retardant and stabilizer combined agent comprising a metal phosphinate, a nitrogen synergist and zinc borate. (3) Exolit ^® OP 1311 (Clariant), flame retardant agent comprising a metal phosphinate and a nitrogen synergist. (4) Exolit ^® OP 1230 (Clariant), flame retardant agent comprising a metal phosphinate. (5) 983 EC ^® 10 Fiberglass Chopped Strands 4.5 mm (Saint-Gobain Vetrotex America), fiberglass used as reinforcing agent. • Preparation of the Polymer Compositions For Example 1, a polymer composition according to the invention was prepared by compounding components (1), (2), (5) in the ratio given in Table 1. For comparative purposes, two other polymer compositions were prepared by separately compounding components (1), (3), (5) (Comparative Example 2) and components (1), (4), (5) (Comparative Example 3), as given in Table 1. Polymer components were compounded by means of a 25 mm Berstorff^® Twin Screw Extruder using identical operating conditions for comparability (temperature profiles, screw geometry, feeding modalities, etc.). Compounding conditions were set to obtain a 280°C melt temperature at the die. Components (l)-(4) were mixed together and then fed into the feed throat of the Berstorff^® Twin Screw Extruder. Component (5) was fed in a separate feeder. Table 1 - Polymer Compositions

■ Properties of the Polymer Compositions The polymer composition of Example 1 (according to the invention), the polymer compositions according to Comparative Examples 2 and 3 and polymer composition LXEF ^® 1521 0008 (i.e. halogenated flame retarded MXD6 composition comprising 50 wt. % of fiberglass, commercially available from Solvay Advanced Polymers L.L.C.) were tested and classified for the flame retardancy, on the basis of the UL 94 (Underwriters Laboratories) test. These compositions were also tested and classified for their thermal stability on the basis of their degradation onset temperature (determined by Thermo Gravimetric Analysis, TGA) and their molding behavior, in particular their tendency to discoloration and out gassing. The results of these tests are reported in Table 2. TGA tests were carried out by means of a Universal V2.60 TA Instruments equipment. A sample having a size in the range 19 to 35 mg was placed into a tared TGA sample pan which was attached to a sensitive microbalance assembly. The sample holder portion of the TGA balance assembly was subsequently placed into a high temperature furnace. The balance assembly measured the initial sample weight at room temperature and then continuously monitored the losses in sample weight as heat was applied to the sample. TGA tests were run in a heating mode at a controlled heating rate. Typical weight loss profiles were analyzed for the amount or percent of weight loss at any given temperature. The degradation onset temperature is that measured at the intersection of the two lines that are tangent, respectively, to the flat portion of the weight loss curve (before degradation) and to its point of inflection.

Table 2 - Properties of the Polymers Compositions and Molding Behavior

From the foregoing examples it is apparent that, the invented polymer composition has better flame resistance (UL 94 V0 at 1.6 mm) and/or improved thermal stability/mold ability in comparison with the halogenated and non halogenated flame retarded MXD6 compositions prepared and tested for comparative purposes.

Claims

C L A I M S

1. Flame retarded and thermally stabilized polymer composition comprising

(i) a thermoplastic polymer and

(ii) a flame retardant and stabilizer combined agent comprising

■ as component (A), a flame retardant selected from the group consisting of a phosphinic salt of the formula (I), a diphosphinic salt of the formula (II), polymers of the formula (I), polymers of the formula (II) and mixtures thereof,

CO o ;p— o M"¹ M-

1 9 characterized in that: R , R are identical or different and are Cl-C-alkyl, linear or branched, or aryl; R is Cl-ClO-alkylene, linear or branched, C6- ClO-arylene, alkylarylene or arylalkylene; M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K, or a protonated nitrogen base; m is 1 to 4; n is 1 to 4; x is 1 to 4, as component (B), a flame retardant synergist selected from the group of nitrogen-containing synergists and phosphorus/nitrogen-containing synergists as component (C), a thermal stabilizer selected from the group of basic or amphoteric oxide, hydroxide, carbonate, silicate, borate, stannate, mixed oxide/hydroxide, oxide/hydroxide/carbonate, hydroxide/silicate, hydroxide/borate, or a mixture thereof optionally as component (D), a phosphonite of the structure R-[P(OR₁)₂]_m (I) characterized in that R is a mono- or polyvalent aliphatic, aromatic, or heteroaromatic organic radical and R\ is a compound of the structure (II)

or the two radicals R_t form a bridging group of the structure (III)

characterized in that: A is a direct bond, O, S, Cl-18-alkylene (linear or branched), or Cl-18-alkylidene (linear or branched); R₂, independently of one another, are C 1 -2-alkyl (linear or branched), C 1 - 12-alkoxy, or C5- 12- cycloalkyl; and n is from 0 to 5, and m is from 1 to 4,

■ optionally as component (E), an ester or salt of montan wax acid,

■ optionally as component (F), a N,N'-bispiperidinyl- 1 ,3-benzenedicarboxamide and/or N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-l,3-benzenedicarboxamide, said polymer composition being characterized in that the thermoplastic polymer (i) is a semi-aromatic polyamide comprising recurring units derived from a dicarboxylic acid component including at least one aliphatic dicarboxylic acid and a diamine component including at least one aromatic diamine.

2. Flame retarded and thermally stabilized polymer composition, according to claim 1, characterized in that the nitrogen-containing synergist of component (B) is of the formulae (IS) to (VIII), or a mixture thereof

where: R⁵ to R⁷ are hydrogen, Cl-C8-alkyl, C5-C16-cycloalkyl or - alkylcycloalkyl, optionally substituted with a hydroxy or a Cl-C4-hydroxyalkyl function, C2-C8-alkenyl, Cl-C8-alkoxy, -acyl, -acyloxy, C6-C12-aryl or - arylalkyl, -OR⁸, or -N(R⁸)R⁹, or a N-alicyclic or N-aromatic system; R⁸ is hydrogen, Cl-C8-alkyl, C5-C16-cycloalkyl or -alkylcycloalkyl, optionally substituted with a hydroxy or a Cl-C4-hydroxyalkyl function, C2-C8-alkenyl, Cl-C8-alkoxy, -acyl, -acyloxy, or C6-C12-aryl or -arylalkyl; R⁹ to R¹³ are the same as the groups for R⁸, or else -O-R⁸; m and n independently of one another, are 1, 2, 3, or 4; X is an acid which forms adducts with triazine compounds (111), or an oligomeric ester of tris(hydroxyethyl) isocyanurate with aromatic polycarboxylic acids.

3. Flame retarded and thermally stabilized polymer composition, according to claims 1-2, characterized in that the phosphorus/nitrogen-containing synergist of component (B) is at least one nitrogen containing phosphate selected from the group of melamine polyphosphate, ammonium hydrogenophosphate, ammonium dihydrogenophosphate, and ammonium polyphosphate.

4. Flame retarded and thermally stabilized polymer composition, according to claims 1-3, characterized in that the thermal stabilizer is zinc borate, magnesium hydroxide, zinc hydroxide, dihydrotalcite, and/or boehmite.

5. Flame retarded and thermally stabilized polymer composition, according to claims 1-3, characterized in that the thermal stabilizer is zinc borate.

6. Flame retarded and thermally stabilized polymer composition, according to claims 1-5, characterized in that the semi-aromatic polyamide comprises recurring units derived from at least one linear aliphatic dicarboxylic acid containing from 4 to 12 carbon atoms and at least one xylylenediamine.

7. Flame retarded and thermally stabilized polymer composition, according to claims 1-5, characterized in that the semi-aromatic polyamide consists of recurring units derived from adipic acid and m-xylylenediamine.

8. Flame retarded and thermally stabilized composition, according to claims 1-7, characterized in that it further comprises fiberglass as reinforcing agent.

9. Flame retarded and thermally stabilized composition, according to claim 8, characterized in that fiberglass is present in amount of at least 45 wt. % and of at most 70 wt. % based on the total weight of the composition.

10. Shaped article, characterized in that it comprises the flame retarded and thermally stabilized polymer composition according to claims 1-9.