WO2021048156A1

WO2021048156A1 - Polymer composition comprising heat stabilizer and use thereof

Info

Publication number: WO2021048156A1
Application number: PCT/EP2020/075123
Authority: WO
Inventors: Stefan Hauck; Pascal Steffanut; Ernesto Dongiovanni
Original assignee: Clariant International Ltd
Priority date: 2019-09-11
Filing date: 2020-09-08
Publication date: 2021-03-18

Abstract

Disclosed are compositions comprising a) a polymer, and b) less than 5 % by weight, referring to the total amount of the composition, of a metal complex comprising a metal Me selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, WO₂, MoO, Zr, Ce and/or Sn, and ligands of formula (II), (III) or (IV) wherein Y represents 0 or S. The metal complex is used as a heat stabilizer in polymers.

Description

Polymer composition comprising heat stabilizer and use thereof

The present invention relates to a polymer composition comprising novel heat stabilizers, to polymer molding compositions and shaped articles made therefrom as well as to their use.

Solid polymeric materials undergo both physical and chemical changes when exposed to heat. This is usually resulting in drastic changes to the properties of the material. Thermal degradation, occurring at high temperatures, causes losses of physical, mechanical or electrical properties. Engineering polymers such as polyamides containing carbonamides possess desirable chemical resistance, processability and heat resistance to match most of the classical requirements in high performance automotive and electrical applications. Nevertheless, particularly in the automotive field for under the hood applications there is constant demand, to replace metal based spare parts by lighter polymeric based ones with proper resistance against degradation at elevated temperatures. Sufficient mechanical properties, critical for this specific end use, should be maintained at a minimum of 150°C and even higher than 200°C for periods longer than 2000 to 5000 hours exposure.

In the past 40 years, phenol-based antioxidants were broadly used as heat stabilizers for thermoplastic compositions comprising polyester or polyamide resins. These chemicals were progressively combined together with copper or zinc-based materials and inorganic salts to increase their overall performances. As shown in US 5,965,652, a thermally stable polyamide moulding composition can be obtained by introducing colloidal copper formed in situ.

An alternative concept is described in GB 839,067 wherein a polyamide composition comprising a copper salt is mixed with a halide of a strong organic base.

Later on, elemental phosphorus or halogenated flame retardants for polyamides were also combined to the inorganic copper-based formulations to limit as well the thermal decomposition and degradation phenomena. However, all these existing formulations and technologies have shown inherent drawbacks like migration or metal release into the environment. With regard to long-term performance those formulations are still insufficient for extended exposure times and higher temperatures. Therefore, it remains a need for better solutions based on innovative materials.

9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or (6H-dibenz [c, e] [1, 2] oxa-phosphorine-6-oxide) (hereinafter also called „DOPO“) is an ester of phosphinic acid, wherein a phosphorous atom and an oxygen atom are incorporated into the base structure of a phenanthrene. DOPO has flame retardant properties and is a base compound for a variety of different halogen-free and very effective flame retardants for polymers.

DOPO may be synthesized by reaction of 2-phenylphenol with phosphorus trichloride in the presence of zinc chloride. The reaction product 6-chlorine (6H)-dibenz[c,e][1,2] oxaphosphorine (DOP-CI) is produced in high yields at high temperatures under hydrochlorine breakdown. When heating the DOP-CI at high temperatures in the presence of water DOPO is quantitatively produced in high purity.

Organo-phosphorous flame retardants with reactive groups, such as those derived from DOPO, are known and broadly described in GB 1256180. Their use as flame retardants for polymers is therein reported and the combination to form corresponding metal salts is disclosed in GB 2049696. Currently typically used in epoxy resin formulations, they have the advantage to react with the epoxy function to form a phosphorus-modified epoxy resin network. The technologies for producing such phosphorus-based compounds are well established and chemical functionalization of DOPO to generate new type molecules which has been largely described in the flame-retardant related literature (e.g. J. Artner et al. , Macromol. Mat. Eng., Vol. 293 (6), pp.503-514 (2008). EP 1,657,972 A1 discloses selected phosphinate-metal-complexes as flame- retardants for polymers, preferably for polyamides.

Surprisingly it has been found that selected metal complexes comprising DOPO or DOPO-OH or their thio analogues can be used alone or in combination with other additives, as efficient heat stabilizers for polymers, preferably for polyamides and polyesters.

Furthermore, it was found that so called engineering plastics, particularly those of the polyamide family, can be stabilized against long-term heat induced degradation by adding selected metal complexes of DOPO (or the respective DOPO-OH and thio analogues) to the corresponding formulations. From a technological point of view, applications with high demanding requirements are in the focus of such new antioxidants. Typical examples are under the hood applications in cars e.g. tubes and hoses.

DOPO or DOPO-OH or their thio analogues correspond to the formula (I) shown below

wherein

Y represents 0 or S, and W represents hydrogen or OH.

Objective of the invention was to provide a heat stabilizer which attributes excellent heat stabilization to a polymer during processing and which stabilizes the polymer composition after molding for a long term.

The present invention relates to a composition comprising a) polymer, and b) less than 5 % by weight, referring to the total amount of the composition, of a metal complex comprising a metal Me selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, WO2, MoO, Zr, Ce and/or Sn, and ligands of formula (II), (III) or (IV)

wherein Y represents 0 or S.

Component a) of the polymer compositions of the invention can be any natural polymer including modifications by chemical treatment or any synthetic polymer. Polymer blends may also be used. Suitable polymers a) include thermoplastic polymers, thermoplastic elastomeric polymers, elastomers or duroplastic polymers.

Preferably thermoplastic polymers are used as component a).

Preferred thermoplastic polymers are selected from the group consisting of polyamides, polycarbonates, polyolefins, polystyrenes, polyesters, polyvinyl chlorides, polyvinyl alcohols, ABS and polyurethanes.

Moreover, duroplastic polymers may be used. These are preferably selected from the group consisting of epoxy resins, phenolic resins and melamine resins.

Additionally, also mixtures of two or more polymers, in particular thermoplastics and/or thermosets may be used.

Examples of polymers preferably used as component a) in the polymer compositions of the present invention are: polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, polybutene-1 , poly-4-methylpentene-1 , polyvinylcyclohexane, polyisoprene or polybutadiene and polymers of cycloolefins, for example of cyclopentene or norbornene, polyethylene (including crosslinked PE), e.g. high density polyethylene (HDPE) or high molecular weight PE (HDPE-HMW), high density polyethylene with ultra- high molecular weight (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE), as well as copolymers of ethylene and vinyl acetate (EVA); polystyrene, poly(p-methylstyrene), poly(alpha-methylstyrene); copolymers and graft copolymers of polybutadiene-styrene or polybutadiene and (meth)acrylonitrile, such as ABS and MBS; halogen-containing polymers, such as polychloroprene, polyvinyl chloride (PVC); polyvinylidene chloride (PVDC), copolymers of vinyl chloride / vinylidene chloride, vinyl chloride / vinyl acetate or vinyl chloride / vinyl acetate; poly(meth)acrylates, polymethyl methacrylates (PMMA), polyacrylamide, and polyacrylonitrile (PAN); polymers of unsaturated alcohols and amines or their acyl derivatives or acetals, such as polyvinyl alcohol (PVA), polyvinyl acetates, stearates, benzoates or maleates, polyvinylbutyrale, polyallylphthalate, and polyallylmelamine; homo- and copolymers of cyclic ethers, such as polyalkylene glycols, polyethylene oxides, polypropylene oxides and copolymers thereof with bisglycidyl ethers; polyacetals, such as polyoxymethylenes (POM) and polyurethane and acrylic modified polyacetales; polyphenylene oxides and sulfides and mixtures thereof with styrene polymers or polyamides; polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 12/12, polyamide 11, polyamide 12, aromatic polyamides derived from m-xylylenediamine and adipic acid and copolyamides modified with EPDM or ABS. Examples of preferred polyamides and copolyamides are those which are derived from e-caprolactam, adipic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid, hexamethylene diamine, tetramethylenediamine, 2-methyl-pentamethylene diamine, 2,2,4-trimethyl-hexamethylene diamine, 2,4,4-tri-methylhexamethylenediamine, m-xylylenediamine or bis(3-methyl- 4-aminocyclohexyl) methane; polyureas, polyimides, polyester imides, polyhydantoins and polybenzimidazoles; polyesters derived from dicarboxylic acids and dialcohols and/or from hydroxy-carboxylic acids or the corresponding lactones, such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, poly-1 , 4- dimethyl cyclohexane terephthalate, polyalkylene naphthalate (PAN) and polyhydroxybenzoates, polylactic acid esters and poly glycolic acid esters; polycarbonates and polyester carbonates; polyketones; mixtures and alloys of the above polymers, for example PP / EPDM, PA / EPDM or ABS, PVC / EVA, PVC / ABS, PBC / MBS, PC / ABS, PBTP / ABS, PC / AS, PC / PBT, PVC / CPE, PVC / acrylic, POM / thermoplastic PUR, PC / thermoplastic PUR, POM / acrylate, POM / MBS, PPO / HIPS, PPO / PA 6.6 and copolymers, PA / HDPE, PA / PP, PA / PPO, PBT / PC / ABS or PBT / PET / PC, and TPE-O, TPE-S and TPE-E; thermosets such as phenol-formaldehyde resins (PF), melamine- formaldeyhde resins (MF) or urea-formaldehyde-resins (UF) or mixtures thereof; epoxy resins; phenolic resins; wood-plastic composites (WPC) and polymers based on PLA, PHB and starch.

Preference is given to polyamides, polyesters, preferably to PET and PBT, polyurethanes, polycarbonates and epoxy resins. Particularly preferred components a) are polyamides and polyesters and most preferred are glass fiber reinforced polyamides and polyesters.

In the case of polyamides, the polymers are preferably those of the amino acid type and/or of the diamine-dicarboxylic acid type.

Preferred polyamides are selected from the group consisting of poly(tetramethylene hexanediamide), poly(s-caprolactam), poly(hexamethylene hexanediamide/(£-caprolactam), poly(hexamethylene hexanediamide), poly(hexamethylene hexanedi-amide/hexamethylene decanediamide), poly(hexamethylene hexanediamide/hexa-methylene dodecanediamide), poly(hexamethylene hexanediamidedecamethylene decanediamide), poly(hexamethylenedecanediamide), poly( hexamethylene dodecanediamide), poly(hexamethylenetetradecanediamide), and poly(tetra-methylene hexanediamide/2-methylpentamethylene hexanediamide}.

The polyamides are preferably aliphatic polyamides, such as polyamide 6, polyamide 12, and polyamide 66, or partially aromatic polyamides. Preference is given to these being partially crystalline polyamides.

Suitable partially aromatic, partially crystalline polyamides are either homopoly amides or copolyamides, the recurring units of which are derived from dicarboxylic acids and diamines and from aminocarboxylic acids or the corresponding lactams. Suitable dicarboxylic acids are aromatic and aliphatic dicarboxylic acids such as, for example, terephthalic acid, isophthalic acid, adipic acid, azeiainic acid, sebacic acid, dodecanedicarboxylic acid and 1 ,4-cyclohexanedicarboxylic acid. Suitable diamines are aliphatic and cycloaliphatic diamines such as hexamethylene- diamine, nona-methylenediamine, decamethylendiamine, dodecamethylene- diamine, 2-methylpenta-methylenediamine, 1 ,4-cyclohexanediamine, di (4-diaminocyclo-hexyl)-methane, di (3-methyl-4-aminocyclohexyl)-methane. Suitable aminocarboxylic acids are aminocaproic acid and aminolauric acid, which can also be used in the form of the corresponding lactams, caprolactam and laurolactam. The melting points of these partially aromatic polyamides are between 280 and 340°C, preferably between 295 and 325°C.

Particularly preferred among the polyamides are those formed from terephthalic acid (TPS), isophthalic acid (IPS) and hexamethyldiamine or from terephthalic acid, adipic acid and hexamethyldiamine. As favorable conditions, approximately 70:30 TPS: IPS and 55:45 TPS: adipic acid have been found. The superior properties are realized in particular by these two special polyamides.

Preference is given to polyamides which contain phenylenediamines or xylylene- diamines as aromatic diamines.

Preference is given to polyamides which contain terephthalic acid or isophthalic acid as aromatic dicarboxylic acids.

Copolyamides are those products made from more than one polyamide-forming monomer. By selecting the monomers and the mixing ratio, the properties of the polyamides can be varied within a very wide range. Compared with the aliphatic copolyamides, certain copolyamides with aromatic monomers are interesting industrial products. They are characterized by a higher glass transition temperature and by a higher melting point of the partially crystalline regions and thus with sufficient for practical use heat resistance. Thus, starting from terephthalic acid and/or isophthalic acid and polyamines such as hexamethylenediamine, semicrystalline polyamides having high heat resistance can be prepared.

Partially aromatic copolyamides suitable according to the invention are described, for example, in Becker / Braun Kunststoff Handbuch 3/4, Polyamides, edited by L. Bottenbruch and R. Binsack, Chapter 6, partially aromatic and aromatic polyamides, pages 803 - 845, to which reference is expressly made. Partly aromatic copolyamides which are suitable according to the invention may also be block copolymers of the above-mentioned polyamides with polyolefins, olefin copolymers, ionomers, or chemically bonded or grafted elastomers; or with polyethers, such as with polyethylene glycol, polypropylene glycol or polytetramethylene glycol. Further modified with EPDM or ABS polyamides or copolyamides; and during processing condensed polyamides ("IM polyamide systems").

Polyesters are preferably selected from the group of reaction products of aromatic or aliphatic dicarboxylic acids or their reactive derivatives (e.g. dimethyl esters or anhydrides) and aliphatic, cycloaliphatic or araliphatic diols and mixtures of these reaction products.

Polyalkylene terephthalates are preferably used. These can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols having 2 to 10 carbon atoms by known methods (Kunststoff-Handbuch, Vol. VIII, p. 695 FF, Karl-Hanser-Verlag, Munich 1973).

Polyethylene terephthalate or polybutylene terephthalate or mixtures of both polyesters are particularly preferred.

The metal complex, component b) defined above, is preferably used in combination with a copper heat stabilizer, organic halogen-containing compounds and mixtures thereof, and/or with bismuth compounds combined with organohalogen compounds, and/or with metal halides and/or with phenolic antioxidants and/or with organic phosphites.

Examples of copper heat stabilizers and organic halogen-containing compounds are combinations of copper complexes and organic halides, such as combinations of chlorine- or bromine-containing organic compounds with complexes of copper with a phosphine compound or with a mercaptobenzimidazole compound. These combinations are disclosed, for example, in WO 00/22035 A1. Further examples of copper heat stabilizers and organic halogen-containing compounds are combinations of copper salts and organic halogen-containing aromatic compounds, aliphatic phosphates and paraffines. These combinations are disclosed, for example, in WO 00/22036 A1.

Examples of bismuth compounds combined with organohalogen compounds are combinations of bismuth oxychloride, bismuth oxyfluoride, bismuth oxybromide, bismuth oxyiodide and bismuth oxynitrate with organobromine compounds. These combinations are disclosed, for example, in WO 2014/099397 A1.

Examples of metal halides are alkali metal halides, preferably iodides and most preferred potassium iodide.

Examples of phenolic antioxidants are disclosed below.

Examples of organic phosphites are aryl phosphites, preferably triphenylphosphite.

Preferred are polymer compositions comprising: i) 40 to 95 weight percent of a polmer, preferably a polyamide, ii) 10 to 60 weight percent of a reinforcing agent, preferably glass fibers, iii) 0.1 to less than 5 weight percent of a metal complex comprising a metal Me selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, WO2, MoO, Zr, Ce and/or Sn and a ligand of formula (II), (III) or (IV) defined above as component b), and optionally iv) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a copper heat stabilizer, an organic halogen-containing compound and mixtures of these or a bismuth compound combined with an organohalogen compound, preferably of a combination of copper complex and an organic halide or of a combination of a copper salt and an organic halogen-containing aromatic compound, aliphatic phosphate and paraffine, and/or v) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a metal halide, preferably an alkali metal iodide and most preferred potassium iodide, and/or vi) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a phenolic antioxidant and/or of an organic phosphite.

The percentages given above refer to the total amount of the polymer composition.

Preferred are polymer compositions comprising: i) 40 to 95 weight percent of a polyamide, ii) 10 to 60 weight percent of a reinforcing agent, iii) 0.1 to less than 5 weight percent of a metal complex of formula (V), (VI) and/or (VII) defined below, and optionally iv) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a copper heat stabilizer, organic halogen- containing compound and mixtures of these or a bismuth compound combined with an organohalogen compound, preferably of a combination of copper complex and an organic halide or of a combination of a copper salt and an organic halogen-containing aromatic compound, aliphatic phosphate and paraffine, and/or v) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a metal halide, preferably an alkali metal iodide and most preferred potassium iodide, and/or vi) 0 to 5 weight percent, preferably between 0.01 and less than 5 % by weight, more preferred between 0.05 and 4 % by weight, and most preferred between 0.1 and 3 % by weight of a phenolic antioxidant and/or of an organic phosphite.

More preferred are polymer compositions comprising the above defined components i), ii), iii) and optionally iv) and/or v) and/or vi) in the above-defined amounts, in which component i) is a polyamide resin having a melting point of greater than 280°C, preferably a polyamide derived from monomers selected from one or more of the group consisting of:

(i-1) liphatic diamines having 4 to 20 carbon atoms or aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms, and/or

(i-2) lactams and/or aminocarboxylic acids having 4 to 20 carbon atoms.

Preferred metal complexes, component b), are those with structures of formulae (V), (VII) or (VII)

wherein Me is a metal selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, W0₂, MoO, Zr, Ce or Sn,

Y is O or S, x is 2, 3 or 4, preferably 2 or 3, d is a number with value x, and e is a number ³1 , preferably 1-10 and most preferably 1.

The number of ligands in formulae (V), (VI) and (VII) is chosen in a way that the resulting complex is electroneutral, thus that the positive charge of Me is compensated by the negative charges of the ligands.

The metal ions Me included in the complexes, component b) of the present invention, are selected from the group consisting of independent from each other from Cu, Mn, Fe, Ti, TiO, Zr, VO, Cr, WO2, MoO, Co, Sn and/or Ce, preferably selected from the group consisting of Cu, Fe, Zr, TiO and/or Ce, and most preferably selected from the group consisting of Fe and/or Ce.

A complex can contain one or more metal ions Me of the same metal or more metal ions Me from different metals. Preferably a complex contains one or more metal ions Me of the same metal.

Most preferably a complex contains one metal ion Me.

Preferred components b) are complexes of formulae (V), (VI) and (VII), wherein Me is selected from Cu, Mn, Fe, Co, Ti, TiO, Zr, VO, Cr, WO2, MoO, Ce or Sn. More preferred components b) are complexes of formulae (V), (VI) and (VII), wherein Me isselected from Cu, Fe, TiO, Zr or Ce .

Most preferred components b) are complexes of formulae (V), (VI) and (VII), wherein Me is selected from Fe or Ce .

The metal complexes comprising ligands derived from DOPO can either contain oxidized ligands, such as in complexes of formula (VII), and/or can contain hydrogenated ligands, such as in complexes of formula (V), and/or can contain hydrated ligands, such as in complexes of formula (VI).

The oxidized species of ligands is in equilibrium with the corresponding hydrogenated or hydrated species of ligands. Depending on the present conditions and the previous history (e.g. the production conditions), the equilibrium can be shifted towards the oxidized species or towards the hydrogenated or hydrated species. In extreme cases, even only the oxidized or hydrogenated or hydrated species might be present.

Preferred components b) are metal complexes having as ligands compounds of formulae (II) and (IV) only.

Also preferred components b) are metal complexes having as ligands compundsof formulae (III) and (IV) only.

Also preferred components b) are metal complexes having as ligands compounds of formula (IV) only.

Preferably components b) are used, wherein the complexes contain a combination of formulae (V) and (VII). The complexes of formula (VII) are in equilibrium with complexes of formula (V) and may be obtained by liberation of hydrogen from complexes of formula (V).

For complexes containing a combination of formulae (VI) and (VII) a similar effect can be observed. In this case complexes of formula (VII) are in equilibrium with complexes of formula (VI) and may be obtained by liberation of water from complexes of formula (VI).

Furthermore, the liberation of either hydrogen or water is possible for all combinations of complexes of the present invention comprising ligands of formulae (II) or (III), where the oxidized species of formula (IV) is in equilibrium with the hydrogenated or hydrated species of formula (II) or (III). Very preferred components b) are iron complexes of formulae (V) and (VII), wherein Me is Fe, x = 2 or 3, Y = 0 or S and n is 1-10, preferably 1

Among these preferred iron complexes those with the following formulae are especially preferred:

in which Y is 0 or S and e is 1 -10, preferably 1.

Preferably the iron compounds having the above formulae are present at 0.1 to less than 5 weight percent, and more preferably about 0.1 to 4, more preferably 0.1 to 3.0, or yet more preferably 0.1 to 2.0 weight percent based on the total weight of the polymer composition.

Component a) is typically present in the polymer composition of this invention between 50 and 95 % by weight and component b) is typically present between 0.01 and less than 5 % by weight. Preferably, component a) is contained in 60 - 90 % by weight, more preferred in 65 - 85 % by weight, and component b) is contained in 0.05 - 4 %, more preferred 0.1 - 3 % by weight in the polymer composition. These percentages refer to the total amount of the polymer composition.

The polymers corresponding to component a) of the composition of this invention are known compounds and can be manufactured by known processes.

For the manufacture of the complexes corresponding to component b) of the composition of this invention, preferably of the compounds of formulae (V), (VI) and (VII), several processes are available.

The manufacturing process of the metal complexes of component b) comprises two subsequent steps and can be performed in analogy to EP 1657972 A1 or in a variation thereof.

In step A, conversion A1 , equimolar amounts of 6H-dibenz[c,e][1 ,2]- oxaphosphorin-6-oxide and sodium, potassium or lithium hydroxide (KatOH) are converted in aqueous phase (see scheme 1). Optionally, alcohols can be added.

Step A in general proceeds at temperatures from 20°C to 90°C, most preferred at 30°C to 70°C. In Step A, conversion A1, 6H-dibenz[c,e][1 ,2]- oxaphosphorin-6-oxide reacts in a ring opening reaction with the added sodium, potassium or lithium hydroxide (KatOH) as depicted in scheme 1.

Step A therefore initially yields the sodium, potassium or lithium salt of 6H-dibenz[c,e][1 ,2]- oxaphosphorin-6-oxide conversion products (Kat-DOPO) as a solution as depicted in scheme 1. The same holds true for DOPO-OH as starting material as well as for all thio-analogues of DOPO and DOPO-OH.

Scheme 1 : Step A, Conversion A1

The latter one (Kat-DOPO) is converted in a subsequent step, where two options are given by either using metal halides or metal sulfates.

EP 1657972 A1 quotes the Zn salt of 6H-dibenz[c,e][1 ,2]-oxaphosphorin-6-oxide as flame retardant, obtained from the conversion of 6H-dibenz[c,e][1 ,2]- oxaphosphorin-6-oxide with NaOH and ZnCl₂ in water. In analogy, the synthesis can be performed in the present case, method A, conversion A2.

For metal halides M^x+(X-)_x with X = F, Cl, Br and/or I and x = 2 or 3 a reaction stoichiometry as depicted in scheme 2 applies (method A, conversion A2) and the number of ligands is chosen in a way that the resulting complex is electroneutral.

Scheme 2: Step A, Conversion A2 (conversions via metal halides):

with x = b and c ³ 1.

The same holds true for DOPO-OH as starting material as well as for all thio- analogues of DOPO and DOPO-OH.

For metal sulfates, depending on the charge of the metal ion, following reaction stoichiometry apply as depicted in schemes 3 and 4 (method A, conversion A3 or A4):

Scheme 3: Method A, conversion A3 (using metal sulfates for M²⁺):

with c ³ 1. The same holds true for DOPO-OH as starting material as well as for all thio- analogues of DOPO and DOPO-OH.

Scheme 4: Method A, conversion 4 (using metal sulfates for M³⁺):

with b = 3 and c ³ 1.

In all cases, the resulting precipitation products are filtered off and washed with water.

Generally, also mixtures of the different metal halides or metal sulfides can be used in combination in one step. From this, mixed complexes can be obtained.

Remarkably, the use of sulfates exhibits technical advantages over the use of halides, namely an improvement of the precipitation. As a result, at comparable yields, smaller quantities of water are required to wash of the resulting salts and therefore low conductivity values can be reached faster than from the halides pathway. At the same time, waste water amounts can be reduced significantly.

Prior to applications of the prepared metal complexes a granulation process can be used. Preferred methods comprise spray driers, spray granulators (top spray, bottom spray, and counter current flow), fluidized bed granulators or paddle dryers. During this process, water remaining from step A can be removed unless a desired degree of residual moisture is reached. Granulation can be conducted by spray drying of an aqueous suspension of the reaction products from step A at 70-80°C. Optionally, a spray granulation starting with a mixture of the educts (flow bed) and spraying of water on to the flow bed with subsequent drying step is feasible. The flow bed temperature is adjusted to 70-80°C, in order the granules to be dried and a free flowing non-dusting granulate to be obtained. Residual moisture of this process is between 0,5 - 1 ,0%.

Step B refers to a calcination taking place in vacuum or at ambient pressure at 130°C to 270°C, preferred at 170°C to 220°C and most preferred at temperatures between 180°C to 200°C.

During this step materials comprising metal complexes of formula (V) liberate hydrogen in a cyclization reaction resulting in a product of formula (VII) given a full conversion of starting material (V). In case of starting material of formula (VI) water is liberated from the initially formed precipitation product and the resulting material comprises metal complexes of formula (VII). Products resulting from the calcination step can contain in any proportion remaining starting material without limiting the scope of the present invention.

Scheme 5 shows the conversion of metal complexes comprising ligands derived from DOPO, meaning ligands of formula (II). Here hydrogen is liberated from the precipitation product of formula (V) and the resulting material is a cyclization product of formula (VII), given full conversion of starting material (V). Furthermore, water still remaining after drying step A, can be released during calcination step B.

Scheme 5: Step B - products (VII) synthesis

Preferably, step B is carried out in a mixer or dryer, electric furnace, rotary furnace or high speed mixer. Most preferably, a vertical or horizontal paddle mixer is used. Special precaution must be taken in case of conversion of precipitation products comprising metal complexes of formula (V) into calcined products containing metal complexes of formula (VII) as the liberation of significant amounts of hydrogen can cause over pressure, fire or explosions.

Products resulting from the calcination step can contain remaining starting material in any proportion without limiting the scope of the present invention.

In the composition comprising components a) and b) preferably may contain as component c) another heat stabilizer, preferably an antioxidant which is different from component b) and/or as component d) a light stabilizer.

Component c) is typically present between 0.01 and less than 5 % by weight, preferably between 0.05 and 4 % by weight, and more preferred between 0.1 and 3 % by weight in the composition of this invention. These percentages refer to the total amount of the composition.

Component d) is typically present between 0.001 and 10 % by weight, preferably between 0.01 and 5 % by weight, and more preferred between 0.1 and 4 % by weight in the composition of this invention. These percentages refer to the total amount of the composition.

Suitable antioxidants, component c), are alkylated monophenols, alkylthiomethyl- phenols, hydroquinones and alkylated hydroquinones, tocopherols, hydroxylated thiodiphenylethers, alkylidene-bisphenols; 0-, N- and S-benzyl compounds, hydroxybenzylated malonates, hydroxybenzyl-aromatics, triazine compunds, benzylphosphonates, acylaminophenols, 4-hydroxylaurin acid amides, 4-hydroxystearic acid anilide, N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamic acid octylester; esters of b-(3.5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with mono- or multivalent alcohols; esters of b-(5-tert-butyl-4-hydroxy-3-methylphenyl)- propionic acid with mono- or multivalent alcohols; esters of b-(3,5-dicyclohexyl-4- hydroxy-phenyl)-propionic acid with mono- or multivaltent alcohols, esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or multivalent alcohols, and/or amides of b-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid.

Preferred alkylated monophenol is 2,6-di-tert-butyl-4-methylphenol.

Preferred alkylthiomethylphenol is 2,4-di-octylthiomethyl-6-tert-butylphenol.

Preferred alkylated hydroquinone is 2,6-di-tert-butyl-4-methoxyphenol.

Preferred tocopherols are a-tocopherol, b-tocopherol, g-tocopherol, d-tocopherol and mixtures thereof (Vitamin E).

Preferred hydroxylated thiodiphenylethers are 2,2'-thio-bis(6-tert-butyl-4-methyl- phenol), 2,2'-thio-bis(4-octylphenol), 4,4'-thio-bis-(6-tert-butyl-3-methylphenol), 4,4'-thio-bis-(6-tert-butyl-2-methylphenol), 4, 4'-thio-bis-(3, 6-di-sec. -amylphenol), and 4,4'-bis-(2,6-di-methyl-4-hydroxyphenyl)-disulfide.

Preferred alkylidene-bisphenol is 2,2'-methylene-bis-(6-tert-butyl-4-methylphenol. Preferred O-benzyl compound is 3,5,3',5'-tetra-tert-butyl-4,4'- dihydroxydibenzylether.

Preferred hydroxybenzylated malonate is dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2- hydroxybenzyl)-malonate.

Preferred hydroxybenzyl-aromatics are 1 ,3,5-tris-(3,5-di-tert-buty)-4- hydroxybenzyl)-2,4,6-trimethylbenzene, 1 ,4-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)- 2,3,5,6-tetramethylbenzene, and 2,4,6-tris-(3,5-di-tert-buryl-4-hydroxybenzyl)- phenol.

Preferred triazine compound is 2,4-bis-octylmercapto-6(3,5-di-tert-butyl-4- hydroxyanilino)-1 ,3,5-triazine. Preferred benzylphosphonate is dimethyl-2, 5-di-tert-butyl-4-hydroxybenzyl- phosphonate.

Preferred amide of b-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid is N, N'-bis- (3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexamethylene diamine, N,N'-bis-(3,5- di-tert-butyl-4-hydroxyphenylpropionyl)-trimethylene diamine, and N,N'-bis-(3,5-di- tert-butyl-4-hydroxyphenylpropionyl)-hydrazine.

Especially preferred components c) are sterically hindered phenols alone or in combination with phosphites.

Suitable light stabilizers, component d), are 2-(2'-hydroxyphenyl)-benzotriazoles, 2-hydroxybenzophenones, esters of optionally substituted benzoic acids, or acrylates.

Preferred 2-(2'-hydroxyphenyl)-benzotriazole is 2-(2'-hydroxy-5'-methylphenyl)- benzotriazole.

Preferred 2-hydroxybenzophenones are the 4-hydroxy, 4-methoxy, 4-octoxy, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy-, 4,2',4-trihydroxy-, 2'-hydroxy-4,4'- dimethoxy-derivative.

Preferred ester of optionally substituted benzoic acids are 4-tert-butyl- phenylsalicylate, phenylsalicylate, octylphenylsalicylate, dibenzoylresorcin, bis-(4- tert-butylbenzoyl)-resorcin, benzoylresorcin, 3,5-di-tert-butyl-4-hydroxybenzoic acid-2, 4-di-tert-butylphenyl ester, 3,5-di-tert-butyl-4-hydroxybenzoic acid hexadecyl ester, 3,5-di-tert-butyl-4-hydroxybenzoic acid octadecyl ester, and 3,5-di-tert-butyl-4-hydroxy-benzoic acid-2-methyl-4,6-di-tert-butylphenylester

Preferred acrylates are a-cyan-p,b-diphenylacrylic acid ethylester or -isooctylester repsectively, a-carbomethoxy-cinnamic acid methylester, a-Cyano-b-methyl-p- methoxy-cinnamic acid methylester or -butylester respectively, a-carbomethoxy-p- methoxy-cinnamic acid methylester, or N-(b-carbomethoxy-b-cyanovinyl)-2- methyl-indoline.

In a preferred variant the composition of the invention contains a metallic heat stabilizer as component c). This enables to get polymer compositions, e.g. cable sheathings with better thermal ageing resistance.

As example of metallic heat stabilizers c) which may be used in accordance with the invention, mention may be made of mineral copper based antioxidants, and more preferably copper salts and complexes such as potassium and copper halogen blends (Kl/Cul) with stearate based or wax binder lubrifiant.

Such metallic antioxidants may be available under the brand BRUGGOLEN^® H3337 sold by BRUGGEMANN CHEMICAL, or POLYAD^® PB 201 IODIDE STAB sold by POLYAD SERVICES.

The total amount of metallic heat stabilizer(s) c) that may be present in the composition of the invention ranges preferably from 0.05 wt.-% to 2 wt.-%, relative to the total weight of the composition.

The polymer composition of the present invention may contain further additives as component e).

The amount of component e) may vary in a broad range. Typical amounts of component e) are between 0 and 60 % by weight, preferably between 1 and 50 % by weight and more preferred between 5 and 30 % by weight, referring to the total amount of the polymer composition.

Examples of additives e) are processing aids, nucleating agents and clarifiers, antistatic agents, lubricants, such as calcium stearate and zinc stearate, viscosity and impact modifiers, compatibilizers and dispersing agents, dyes or pigments, antidripping agents, flame-retardants, fillers and/or reinforcing agents. The polymer composition of the present invention preferably contains additional fillers. These are are preferably selected from the group consisting of metal hydroxides and/or metal oxides, preferably alkaline earth metal, e.g. magnesium hydroxide, aluminum hydroxide, silicates, preferably phyllosilicates, such as bentonite, kaolinite, muscovite, pyrophyllite, marcasite and talc or other minerals, such as wollastonite, silica such as quartz, mica, feldspar and titanium dioxide, alkaline earth metal silicates and alkali metal silicates, carbonates, preferably calcium carbonate and talc, clay, mica, silica, calcium sulfate, barium sulfate, pyrite, glass beads, glass particles, wood flour, cellulose powder, carbon black, graphite and chalk.

The polymer composition of the present invention preferably contains reinforcing agents, more preferred reinforcing fibers. These are are preferably selected from the group consisting of glass fibers, carbon fibers, aramid fibers, potassium titanate whiskers, glass fibers being preferred. The incorporation of the reinforcing agents in the molding compositions can be done either in the form of endless strands (rovings) or in cut form (short glass fibers). To improve the compatibility with the polymer matrix, the reinforcing fibers used can be equipped with a size and an adhesion promoter. The diameter of commonly used glass fibers is typically in the range of 6 to 20 microns.

These additives e) can impart other desired properties to the polymer composition of the invention. In particular, the mechanical stability can be increased by reinforcement with fibers, preferably with glass fibers.

The polymer compositions of the invention are preferably prepared by providing the components a), b), and optionally c) and/or d) and/or e), e.g. by mixing or by incorporation into a masterbatch, and by incorporating the components b) and optionally c) and/or d) and/or e) into the polymer or polymer mixture.

The components b) and optionally c) and/or d) and/or e) can be incorporated into the polymer a) by premixing all components as powder and/or granules in a mixer and then homogenizing them in the polymer melt in a compounding unit (e.g. a twin-screw extruder). The melt is usually withdrawn as a strand, cooled and granulated. The components b) and optionally c) and/or d) and /or e) can also be introduced separately via a metering system directly into the compounding unit. It is also possible to admix the components b) and optionally c) and/or d) and/or e) to a finished polymer granulate or powder and to process the mixture directly to form parts, e.g. on an injection molding machine.

The process for the production of polymer compositions is characterized by incorporating and homogenizing the components b) and optionally c) and/or d) and/or e) into polymer pellets in a compounding assembly at elevated temperatures. The resulting homogenized polymer melt is then formed into a strand, cooled and portioned. The resulting granules are dried, e.g. at 90°C in a convection oven.

Preferably, the compounding equipment is selected from the group of single-screw extruders, multizone screws, or twin-screw extruders.

The polymer compositions according to the invention are suitable for the production of moldings, e.g. films, threads and fibers. The polymer compositions may be shaped into articles using methods known to those skilled in the art, such as injection moulding, blow moulding, injection blow moulding, extrusion, thermoforming, melt casting, vacuum moulding, rotational moulding, calendar moulding, slush moulding, filament extrusion and fibre spinning.

The molded or extruded articles may be used as components for automobiles, including various electric and electronic components. Specific examples of moulded or extruded articles are selected from the group consisting of charge air coolers (CAC), cylinder head covers (CHC), oil pans, engine cooling systems, including thermostat and heater housings and coolant pumps, exhaust systems, including mufflers and housings for catalytic converters, air intake manifolds (AIM), and timing chain belt front covers. The invention also relates to a molding prepared from a composition containing components a) and less than 5 % by weight of b), and optionally c) and/or d) and/or e).

Articles prepared from polymer compositions that exhibit the combination of a desirable heat stability at 200°C while simultaneously having a heat aged tensile strength of at least 100 MPa are highly desirable for use in demanding high temperature applications.

It has surprisingly been discovered that polymer compositions, preferably polyamide compositions, comprising polymer a) and less than 5 % by weight of metal complex b),and optionally components c) and/or d) and/or e) as disclosed above exhibit a high elongation at break after heat aging and simultaneously exhibit a high heat aged tensile strength, as demonstrated in the examples portion below.

The invention furthermore relates to the use of metal complexes defined above as component b) as a heat stabilizer in polymers, preferably as an antioxidant in polymer compositions.

Finally, the invention relates to the use of the polymer compositions comprising components a), b), d) and optionally c) and/or e) for the manufacture of heat- stabilized polymer molding compositions, which are processed by injection moulding (e.g. injection molding machine (Aarburg Allrounder type)), compression molding, foam injection molding, internal gas pressure injection molding, blow molding, film casting, calendering, laminating or coating at elevated temperatures

Examples

The following examples serve to illustrate the invention.

Experimental results for the synthesis of DOPO and DOPO-OH complexes:

DOPO derivatives: Example 1: Preparation of Cu(DOPO)2

100,00 g (0,463 mol) 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were suspended in 500 ml of water while stirring. Subsequently, 55,59 g (0,463 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 32,10 g (0,2315 mol) of copper(ll) chloride dissolved in 250 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting dark precipitate was filtered by suction, washed with water and dried to constant weight at 110°C.

Yield: 102,55 g (83,6% of theory)

P(calc.): 11 ,69 % P(found): 11 ,60 %

Cu(calc.): 11 ,99 % Cu(found): 11 ,90 %

Conductivity: 510 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

Example 2: Preparation of Ce(DOPO)3

250,00 g (1,156 mol) 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were suspended in 2000 ml of water while stirring. Subsequently,

139,00 g (1,156 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 143,78 g (0,385 mol) of cerium chloride dissolved in 250 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting white precipitate was filtered by suction, washed with water and dried to constant weight at 110°C.

Yield: 285,70 g (88,38% of theory)

P(calc.): 11 ,07 % P(found): 11 ,00 %

Ce(calc.): 16,69 % Ce(found): 16,60 %

Conductivity: 526 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

Example 3: Preparation of Fe(DOPO)2 via FeSO4 x 7H2O

10,00 g (0,0463 mol) 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide

(DOPO) were suspended in 200 ml of water while stirring. Subsequently, 5,59 g (0,0463 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 6,43 g (0,02315 mol) of iron(ll) sulfate heptahydrate dissolved in 50 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting dark precipitate was filtered by suction, washed with water and dried to constant weight at 110°C.

Yield: 11 ,04 g (91 ,32 % of theory)

P(calc.): 11 ,86 % P(found): 11 ,70 %

Fe(calc.): 10,69 % Fe(found): 10,70 %

Conductivity: 427 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

Example 4: Preparation of Fe(DOPO)3 via Fe2(S04)2 x H2O 10,00 g (0,0463 mol) 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were suspended in 200 ml of water while stirring. Subsequently, 5,59 g (0,0463 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 3,91 g (0,00771 mol) of iron(lll) sulfate hydrate dissolved in 50 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting dark precipitate was filtered by suction, washed with water and dried to constant weight at 110°C. Yield: 10,65 g (91,42 % of theory)

P(calc.): 12,30 % P(found): 12,20 %

Fe(calc.): 7,39 % Fe(found): 7,30 %

Conductivity: 411 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

DOPO-OH derivatives:

Example 5: Preparation of Fe(DOPO-OH)2 via FeSO4 x 7H2O

10,00 g (0,043 mol) 10-Hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide (DOPO-OH) were suspended in 200 ml of water while stirring.

Subsequently, 5,17 g (0,043 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 5,99 g (0,0215 mol) iron(ll) sulfate heptahydrate dissolved in 50 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting dark precipitate was filtered by suction, washed with water and dried to constant weight at 110°C.

Yield: 10,54 g (88,42 % of theory)

P(calc.): 11,18 % P(found): 11,10 %

Fe(calc.): 10,08 % Fe(found): 10,00 %

Conductivity: 400 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

Example 6: Preparation of Fe(DOPO-OH)3 via Fe2(S04)3 x H2O

Subsequently, 5,17 g (0,0043 mol; 33% aq. solution) NaOH were added, to give a clear solution. Then, a solution of 3,64 g (0,00718 mol) iron(lll) sulfate hydrate dissolved in 50 ml water is added dropwise. The solution becomes turbid. The reaction mixture was stirred for 1 h at 70°C. After cooling to room temperature, the resulting dark precipitate was filtered by suction, washed with water and dried to constant weight at 110°C.

Yield: 10,41 g (90,29 % of theory)

P(calc.): 11 ,57 % P(found): 11 ,50 %

Fe(calc.): 6,95 % Fe(found): 7,00 %

Conductivity: 330 ms / cm (10% suspension in distilled water, following centrifugation; measured with a calibrated conductivity meter.)

In analogy to these examples, also other compounds according to the present invention can be prepared.

Application examples

Compounding Method

Prior to use polyamide-6.6 has been dried in a Jet-Box dryer at T= 80°C until a humidity content of < 0.1 wg-% was reached. Test specimen were then prepared according to Table 1 : Tested recipies

Extrusion conditions

The compounds were extruded using a twin-screw extruder type Leistritz ZSE 27 HP - 44D at cylinder temperature profile 280-280-285-280-270-260-260-260-260- 260-255°C, a die temperature of 255°C, a screw speed of 250 rpm and 20kg/h output. The extruded string was cooled in a water bath and finally chopped into granules. The cooling and cutting conditions were adjusted to ensure that the materials were kept at minimum moisture level.

Preparation of samples for oven aging and measurements of physical properties Bars (sizes 80mm x 10mm x 4mm) as well as plaques (sizes 60mm x 60mm x 1mm) have been prepared by injection moulding for oven storage and subsequent physical measurements. Injection moulding was carried out with an injection moulding machine type Arburg 320C Allrounder with a ramping temperature profile 270-280-285-295-305°C and a mold temperature of 80°C with a maximum injection pressure of 1573 bar and a cycle time of 27.7 seconds.

Oven Ageing (OA)

The test specimens were heat-aged in a re-circulating air oven (Memmert type ULE, UFM) according to the procedure detailed in ISO 2578. At various heat aging times, the test specimens were removed from the oven, allowed to cool to room temperature and sealed into aluminium lined bags until ready for testing.

Measurements of Physical Properties

Mechanical properties i.e. impact energy, elongation at break (tensile strength) and strain at break (elongation at break, maximum strength at break) were measured according to ASTM D 638. Measurements were done on injection moulded ISO tensile bar (melt temperature 295-300° C; mould temperature 100° C and a hold pressure of 85 MPa with a thickness of the test specimen of 4mm and a width of 10mm and a length of 80mm according to ISO 527/1 A at a testing speed of 5 mm/min (tensile strength and elongation). Tensile trials

The tensile mechanical properties were then measured according to ASTM D 638 using a Zwick type Z020 tensile instrument. An elongation speed of 50mm/min., a load cell of 1000kg and a grip distance of 11.5 cm was selected. Five test specimens have been prepared from each formulation. The average values obtained from these five specimens are given in the Tables 1-3.

Table 1: Test recipies

Table 2: Influence of oven aging at 200°C for 1500 hours on impact energy

Table 3A: Influence of 1000 hours oven aging at 200°C on elongation at break

Table 3B: Influence of 2000 hours oven aging at 200°C on elongation at break

Table 4A: Influence of 1000 hours oven aging at 200°C on maximum strength at break

Table 4B: Influence of 2000 hours oven aging at 200°C on maximum strength at break

Table 5: Influence of 2000 hours oven aging at 200°C on color

These results demonstrate that the metal complexes used in this invention, particularly the Ce- and Fe-complexes, are long term heat stabilizers of polymers, such as polyamides. These compounds are capable to outperform state-of-the-art stabilizer systems mostly based on copper salts towards maintenance of mechanical properties. This is an important technical process e.g. for applications in the motorized vehicle segment, particularly for thermally demanding under-the- hood applications.

Claims

Patent Claims

1. A composition comprising a) a polymer, and b) less than 5 % by weight, referring to the total amount of the composition, of a metal complex comprising a metal Me selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, WO2, MoO, Zr, Ce and/or Sn, and ligands of formula (II), (III) or (IV)

wherein Y represents 0 or S.

2. The composition according to claim 1 , wherein the polymer a) is a thermoplastic polymer, preferably a polyamide, polycarbonate, polyolefin, polystyrene, polyester, polyvinyl chloride, polyvinyl alcohol, ABS and polyurethane.

3. The composition according to claim 2, wherein the polymer is a polyamide or a polyester, preferably a polyamide.

4. The composition according to at least one of claims 1 to 3, wherein component b) is a metal complex having the structure of formulae (V), (VI) or (VII)

wherein Me and Y are as defined in claim 1 , x is 2, 3 or 4, d is a number with value x, and e is a number ³1.

5. The composition according to at least one of claims 1 to 4, wherein the metal ions Me included in the complex are selected from the group consisting of Cu, Fe, TiO, Zr and/or Ce, preferably selected from the group consisting of Fe and/or Ce.

6. The composition according to at least one of claims 1 to 5, wherein component b) is an iron complex with one of the following formulae:

in which Y is 0 or S and e is 1 -10, preferably 1.

7. The composition according to at least one of claims 1 to 6, wherein component a) is present in 60 - 90 % by weight, preferred in 65 - 85 % by weight, and component b) is contained in 0.05 - 4 % by weight, preferred in 0.1 - 3 % by weight, wherein these percentages refer to the total amount of the polymer composition.

8. The composition according to claim 4 comprising i) 40 to 95 weight percent of a polyamide, ii) 10 to 60 weight percent of a reinforcing agent, iii) 0.1 to less than 5 weight percent of a metal complex of formula (V), (VI) and/or (VII) according to claim 4, and optionally iv) 0 to 5 weight percent of a copper heat stabilizer, organic halogen-containing compound and mixtures of these or of a bismuth compound combined with an organohalogen compound, and/or v) 0 to 5 weight percent of a metal halide, and/or vi) 0 to 5 weight percent of a phenolic antioxidant and/or of an organic phosphite, wherein the percentages refer to the total amount of the composition.

9. The composition according to claim 8 comprising i) 40 to 95 weight percent of a polyamide, ii) 10 to 60 weight percent of a reinforcing agent, iii) 0.1 to less than 5 weight percent of a metal complex of formula (V), (VI) and/or (VII) according to claim 4, and iv) between 0.05 and 4 % by weight of a combination of copper complex and an organic halide or of a combination of a copper salt and an organic halogen-containing aromatic compound, aliphatic phosphate and paraffine, and v) between 0.05 and 4 % by weight of an alkali metal iodide , and vi) between 0.05 and 4 % by weight of a phenolic antioxidant and/or of an organic phosphite.

10. The composition according to at least one of claims 1 to 7, wherein an additional component c) being another heat stabilizer different from component b) and/or d) being a light stabilizer is present.

11. The composition according to claim 10, wherein component c) is selected from the group consisting of alkylated monophenols, alkylthiomethylphenols, hydroquinones and alkylated hydroquinones, tocopherols, hydroxylated thiodiphenylethers, alkylidene-bisphenols, 0-, N- and S-benzyl compounds, hydroxybenzylated malonates, hydroxybenzyl-aromatics, triazine compounds, benzylphosphonates, acylaminophenols, 4-hydroxylaurin acid amides, 4-hydroxystearic acid anilide, N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamic acid octylester; esters of b-(3.5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with mono- or multivalent alcohols; esters of b-(5-tert-butyl-4-hydroxy-3-methylphenyl)- propionic acid with mono- or multivalent alcohols; esters of b-(3,5-dicyclohexyl-4- hydroxy-phenyl)-propionic acid with mono- or multivaltent alcohols, esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or multivalent alcohols, and/or amides of b-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid.

12. The composition according to at least one of claims 1 to 11 , wherein the polymer composition contains further additives as component e).

13. The composition according to claim 12, wherein the additive e) is a filler and/or a reinforcing agent.

14. A shaped article containing components a) and b) according to any of claims 1 to 6.

15. Use of a metal complex comprising a metal Me selected from the group consisting of Cu, Mn, Fe, Co, Ti, TiO, VO, Cr, WO2, MoO, Zr, Ce and/or Sn, and ligands of formula (II), (III) or (IV)

wherein Y represents 0 or S as a heat stabilizer in polmyers.

16. The use according to claim 14, whererin the heat-stabilizer is a metal- complex of at least one of claims 4 to 6.

17. Use of a composition according to at least one of claims 1 to 13 for the manufacture of heat-stabilized polymer molding compositions, which are processed by injection moulding, compression molding, foam injection molding, internal gas pressure injection molding, blow molding, film casting, calendering, laminating or coating at elevated temperatures