HK1262883A1 - Flame-retardant polyamide compositions and use thereof - Google Patents

Description

Flame-retardant polyamide composition and use thereof

Technical Field

The present invention relates to flame retardant polyamide compositions and molded articles made therefrom.

Background

Flammable plastics must generally be equipped with flame retardants in order to be able to meet the high flame retardancy requirements demanded by plastic processors and partly by legislators. Preferably, also for ecological reasons, non-halogenated flame retardant systems are used, which form only little or no smoke.

In these flame retardants, salts of phosphinic acids (phosphinates) have proven to be particularly effective for thermoplastic polymers (DE 2252258A and DE 2447727A).

Furthermore, synergistic combinations of phosphinic salts with specific nitrogen-containing compounds are known, which are more effective as flame retardants in a series of polymers than the phosphinic salts alone (WO-2002/28953A 1 and DE 19734437A 1 and DE 19737727A 1).

From US 7,420,007B2 it is known that dialkylphosphinic salts which contain small amounts of selected telomers are suitable as flame retardants for polymers which undergo only very little degradation when the flame retardant is incorporated into a polymer matrix.

Flame retardants must often be incorporated in high doses to ensure adequate fire resistance of plastics according to international standards. Due to their chemical reactivity, which is required for flame-retardant action at high temperatures, flame retardants can impair the processing stability of plastics, especially at higher dosages. Which may lead to enhanced polymer degradation, crosslinking reactions, gas release or discoloration.

Polyamide moulding compounds are known from WO 2014/135256 a1, which have significantly improved thermal stability, reduced migration tendency and good electrical and mechanical properties.

However, flame-retardant phosphinate-containing polyamide compositions which simultaneously achieve all the desired properties, such as good flowability, good electrical values and effective flame retardancy, without at the same time having a tendency to discoloration, have hitherto been lacking.

Disclosure of Invention

It was therefore an object of the present invention to provide flame-retardant polyamide compositions based on phosphinate-containing flame-retardant systems which simultaneously have all the abovementioned properties and which in particular have good flowability (MVR), good electrical values (GWFI, CTI) and effective flame retardancy (UL94), wherein at the same time no tendency toward discoloration (color) occurs.

The subject of the present invention is therefore a flame-retardant polyamide composition comprising

A polyamide as component A having a melting point of less than or equal to 290 ℃, preferably less than or equal to 280 ℃ and very particularly preferably less than or equal to 250 ℃,

as fillers and/or reinforcements of component B, preferably glass fibers,

phosphinic acid salts of the formula (I) as component C

Wherein R is₁And R₂Represents an ethyl group, and represents a linear or branched alkyl group,

m is Al, Fe, TiO_pOr a combination of Zn and a metal selected from the group consisting of,

m represents 2 to 3, preferably 2 or 3, and

p＝(4–m)/2，

-as component D a compound selected from: al, Fe, TiO salts of ethylbutylphosphinic acid, dibutylphosphinic acid, ethylhexylphosphinic acid, butylhexylphosphinic acid and/or dihexylphosphinic acid_pA salt or a Zn salt, wherein the Zn salt is a zinc salt,

phosphonates of the formula II as component E

Wherein R is₃Represents an ethyl group, and represents a linear or branched alkyl group,

met is Al, Fe, TiO_qOr a combination of Zn and a metal selected from the group consisting of,

n represents 2 to 3, preferably 2 or 3, and

q＝(4–n)/2，

melamine polyphosphate having an average degree of condensation greater than or equal to 20 as component F,

as component G, a sterically hindered phenolic antioxidant, and/or

Organic phosphites and/or organic phosphonites as component H.

In the polyamide composition according to the invention, the fraction of component a is generally from 25 to 95% by weight, preferably from 25 to 75% by weight.

In the polyamide composition according to the invention, the fraction of component B is generally from 1 to 45% by weight, preferably from 20 to 40% by weight.

In the polyamide composition according to the invention, the fraction of component C is generally from 1 to 35% by weight, preferably from 5 to 20% by weight.

In the polyamide composition according to the invention, the fraction of component D is generally from 0.01 to 3% by weight, preferably from 0.05 to 1.5% by weight.

In the polyamide composition according to the invention, the fraction of component E is generally from 0.001 to 1% by weight, preferably from 0.01 to 0.6% by weight.

In the polyamide composition according to the invention, the fraction of component F is generally from 1 to 25% by weight, preferably from 2 to 10% by weight.

In the polyamide composition according to the invention, the fraction of component G is generally from 0.01 to 5% by weight, preferably from 0.5 to 1% by weight.

In the polyamide composition according to the invention, the fraction of component H is generally from 0.01 to 5% by weight, preferably from 0.5 to 1% by weight.

In this case, the percentage values of the fractions of components A to H are based on the total amount of the polyamide composition.

Preferred are flame retardant polyamide compositions wherein

The proportion of component A is from 25 to 95% by weight,

the proportion of component B is from 1 to 45% by weight,

the proportion of component C is from 1 to 35% by weight,

the proportion of component D is from 0.01 to 3% by weight,

the proportion of component E is from 0.001 to 1% by weight,

the proportion of component F is from 1 to 25% by weight,

the proportion of component G is from 0.05 to 5% by weight, and

the proportion of component H is from 0.05 to 5% by weight,

wherein the percentage values are based on the total amount of the polyamide composition.

Particularly preferred are flame retardant polyamide compositions wherein

The proportion of component A is from 25 to 75% by weight,

the proportion of component B is from 20 to 40% by weight,

the proportion of component C is from 5 to 20% by weight,

the proportion of component D is from 0.05 to 1.5% by weight,

the proportion of component E is from 0.01 to 0.6% by weight,

the proportion of component F is from 2 to 10% by weight,

the proportion of component G is from 0.1 to 1% by weight, and

the proportion of component H is from 0.1 to 1% by weight.

Preferred salts of component C are those in which M is^m+Represents Zn²⁺、Fe³⁺Or especially Al³⁺Those of (a).

Preferred salts for component D are zinc salts, iron salts or, in particular, aluminum salts.

Preferred salts of component E are those in which Metⁿ⁺Represents Zn²⁺、Fe³⁺Or especially Al³⁺Those of (a).

Very particular preference is given to flame-retardant polyamide compositions in which M and Met denote Al, M and n are 3 and in which the compound of component D is present as an aluminum salt.

In a preferred embodiment, the above flame retardant polyamide composition comprises as further component I an inorganic phosphonate.

The use of inorganic phosphonates or also salts of phosphorous acid (phosphites) as flame retardants to be used according to the invention as component I is known. Thus, WO 2012/045414 a1 discloses flame retardant combinations which, in addition to the phosphinates, also contain salts of phosphorous acid (═ phosphites).

Preferably, the inorganic phosphonate (component I) corresponds to the general formula (IV) or (V)

[(HO)PO₂]^2- _p/2Kat^p+(IV)

[(HO)₂PO]^- _pKat^p+(V)

Wherein Kat is a p-valent cation, in particular of an alkali metal, of an alkaline earth metal, an ammonium cation and/or a cation of Fe, Zn or, in particular, of Al, including the cations Al (OH) or Al (OH)₂And p represents 1, 2,3 or 4.

Preferably, the inorganic phosphonate (component I) is aluminum phosphite [ Al (H)₂PO₃)₃]Next timeAluminum phosphite [ Al ]₂(HPO₃)₃]Basic aluminum phosphites [ Al (OH) (H)₂PO₃)₂*2aq]Aluminum phosphite tetrahydrate [ Al₂(HPO₃)₃*4aq]Aluminum phosphonate, Al₇(HPO₃)₉(OH)₆(1, 6-hexanediamine)_1.5*12H₂O，Al₂(HPO₃)³*xAl₂O₃*nH₂O wherein x is 2.27-1 and/or Al₄H₆P₁₆O₁₈。

The inorganic phosphonate (component I) is preferably also an aluminum phosphite of the formula (VI), (VII) and/or (VIII)

Al₂(HPO₃)₃x(H₂O)_q(VI)，

Wherein q represents a number of 0 to 4,

Al_2.00M_z(HPO₃)_y(OH)_vx(H₂O)_w(VII)，

wherein M represents an alkali metal cation, z represents 0.01 to 1.5 and y represents 2.63 to 3.5 and v represents 0 to 2 and w represents 0 to 4;

Al_2.00(HPO₃)_u(H₂PO₃)_tx(H₂O)_s(VIII)

wherein u represents 2 to 2.99 and t represents 2 to 0.01 and s represents 0 to 4, and/or

Is aluminum phosphite [ Al (H)₂PO₃)₃]Is given byAluminum phosphite [ Al ]₂(HPO₃)₃]Basic aluminum phosphite [ Al (OH) (H)₂PO₃)₂*2aq]Is aluminum phosphite tetrahydrate [ Al ]₂(HPO₃)₃*4aq]Being aluminium phosphonate, being Al₇(HPO₃)₉(OH)₆(1, 6-hexanediamine)_1.5*12H₂O is Al₂(HPO₃)³*xAl₂O₃*nH₂O wherein x is 2.27-1 and/or Al₄H₆P₁₆O₁₈。

Preferred inorganic phosphonates (component I) are salts which are insoluble or poorly soluble in water.

Particularly preferred inorganic phosphonates are aluminum, calcium and zinc salts.

Particularly preferably, component F is the reaction product of phosphorous acid and an aluminum compound.

Particularly preferred components F are aluminum phosphites having CAS numbers 15099-32-8, 119103-85-4, 220689-59-8, 56287-23-1, 156024-71-4, 71449-76-8 and 15099-32-8.

The preparation of the preferably used aluminum phosphite is carried out by reacting an aluminum source with a phosphorus source and optionally a template in a solvent at 20-200 ℃ during a time interval of up to 4 days. For this purpose, an aluminum source and a phosphorus source are mixed for 1 to 4 hours, heated under hydrothermal conditions or under reflux, filtered, washed and dried, for example at 110 ℃.

Preferred aluminium sources are aluminium isopropoxide, aluminium nitrate, aluminium chloride, aluminium hydroxide (e.g. pseudoboehmite).

Preferred phosphorus sources are phosphorous acid, aluminum (acidic) phosphite, alkali metal salts of phosphorous acid or alkaline earth metal salts of phosphorous acid.

Preferred alkali metal salts of phosphorous acid are disodium phosphite, disodium phosphite hydrate, trisodium phosphite, potassium hydrogenphosphite.

A preferred disodium phosphite hydrate is Br ü ggemannH10。

Preferred templates are 1, 6-hexanediamine, guanidine carbonate or ammonia.

The preferred alkaline earth metal phosphite is calcium phosphite.

The preferred ratio of aluminium to phosphorus to solvent is in this case 1:1:3.7 to 1:2.2:100 mol. The ratio of the aluminum to the template is 1:0 to 1:17 mol. The reaction solution preferably has a pH of 3 to 9. The preferred solvent is water.

Particularly preferably, the same salts of phosphinic acid as phosphorous acid are used in the application, i.e. for example aluminum diethylphosphinate together with aluminum phosphite or zinc diethylphosphinate together with zinc phosphite.

In a preferred embodiment, the above flame retardant polyamide composition comprises as component I a compound of formula (III)

Wherein Me is Fe and TiO_rZn or, in particular, Al,

o represents 2 to 3, preferably 2 or 3, and

r＝(4–o)/2。

the compounds of the formula III which are preferably used are those in which Me^o+Represents Zn²⁺、Fe³⁺Or especially Al³⁺Those of (a).

Component I is preferably present in an amount of from 0.005 to 10% by weight, in particular in an amount of from 0.02 to 5% by weight, based on the total amount of the polyamide composition.

Preferred are flame retardant polyamide compositions according to the invention having a relative tracking index, measured according to the international electrotechnical commission standard IEC-60112/3, of more than 500 volts.

The flame retardant polyamide composition according to the invention, which is also preferred, achieves the evaluation of V0 according to UL-94, in particular for measurements on moldings having a thickness of from 3.2mm to 0.4 mm.

Further preferred flame retardant polyamide compositions according to the invention have a glow wire flammability index according to IEC-60695-2-12 of at least 960 ℃, in particular measured on moldings having a thickness of from 0.75 to 3 mm.

The polyamide composition according to the invention comprises as component a one or more polyamides having a melting point of less than or equal to 290 ℃. The melting point is determined in this case by means of Differential Scanning Calorimetry (DSC) at a heating rate of 10K/sec.

The polyamides of component A are generally homopolyamides or copolyamides which are derived from (cyclo) aliphatic dicarboxylic acids or their polyamide-forming derivatives, such as salts thereof, and from (cyclo) aliphatic diamines or from (cyclo) aliphatic aminocarboxylic acids or their polyamide-forming derivatives, such as salts thereof.

The polyamides used according to the invention as component A are thermoplastic polyamides.

Thermoplastic polyamides are understood by reference to Hans Dominghaus in "Die Kunststoffe und ihrer Eigenschaften", 5 th edition (1998), page 14 as polyamides whose molecular chains have no or also more or less long and different in number of side chain branches, soften under heat and are almost arbitrarily shapeable.

The polyamides used according to the invention as component A can be prepared in a variety of different ways and synthesized from a variety of structural units and, in the case of particular applications, are provided as materials having a particularly tailored combination of properties, alone or in combination with processing aids, stabilizers or also polymeric alloy partners, preferably elastomers. Also suitable are blends with fractions of other polymers, preferably polyethylene, polypropylene, ABS, where optionally one or more compatibilizers may be used. The properties of the polyamide can be improved by the addition of an elastomer, for example in terms of impact toughness, especially when it is a glass-fibre-reinforced polyamide. The large number of combination possibilities makes possible very large numbers of products with various properties.

For the preparation of polyamides, numerous routes are known in which, depending on the desired end product, different monomeric building blocks are used, various chain regulators for adjusting the molecular weight sought or also monomers having reactive groups for the later intended aftertreatment.

Industrially relevant processes for preparing polyamides are mostly carried out by polycondensation in the melt. Within this range, hydrolytic polymerization of lactams is also understood as polycondensation.

Preferably, the polyamides to be used as component A are partially crystalline aliphatic polyamides, which can be prepared from aliphatic diamines and aliphatic dicarboxylic acids and/or cycloaliphatic lactams having at least 5 ring members or the corresponding amino acids.

As reactants, aliphatic dicarboxylic acids are considered, preferably adipic acid, 2, 4-trimethyladipic acid and 2,4, 4-trimethyladipic acid, azelaic acid and/or sebacic acid, aliphatic diamines, preferably tetramethylenediamine, hexamethylenediamine, 1, 9-nonanediamine, 2, 4-trimethylhexamethylenediamine and 2,4, 4-trimethylhexamethylenediamine, the isomeric diaminodicyclohexylmethanes, diaminodicyclohexylpropanes, bis (aminomethyl) cyclohexanes, aminocarboxylic acids, preferably aminocaproic acid or the corresponding lactams. Including copolyamides composed of a plurality of the above monomers. Caprolactam is particularly preferred, and epsilon-caprolactam is very particularly preferred.

Preferably, the aliphatic homo-or copolyamides used according to the invention are polyamide 12, polyamide 4,6, polyamide 6,9, polyamide 6,10, polyamide 6,12, polyamide 6,66, polyamide 7, polyamide 8, polyamide 9, polyamide 10, polyamide 11 or polyamide 12. These are for example under the trade name DuPontTrade name of BASF corporationOf DSM companyK122, DuPont corporation7301; from Bayer corporationB29 and Ems ChemieAre known.

Also particularly suitable are compounds based on PA6, PA6,6 and other aliphatic homo-or copolyamides in which there are 3 to 11 methylene groups for one polyamide group in the polymer chain.

Preferred are flame retardant polyamide compositions wherein as component a one or more polyamides selected from PA6, PA 4,6, PA 12, PA6, 10 are used.

Particularly preferred are flame retardant polyamide compositions wherein polyamide 6,6 or a polymer mixture of polyamide 6,6 and polyamide 6 is used as component a.

Very particular preference is given to flame-retardant polyamide compositions in which at least 75% by weight of component A consists of polyamide 6,6 and at most 25% by weight consists of polyamide 6.

As component B, fillers and/or preferably reinforcing materials, preferably glass fibers, are used. Mixtures of two or more different fillers and/or reinforcing materials may also be used.

Preferred fillers are mineral particulate fillers based on talc, mica, silicates, quartz, titanium dioxide, wollastonite, kaolin, amorphous silica, nanoscale minerals, particularly preferably montmorillonite or nano-boehmite, magnesium carbonate, chalk, feldspar, glass beads and/or barium sulfate. Particularly preferred are mineral particulate fillers based on talc, wollastonite and/or kaolin.

Particularly preferably, acicular mineral fillers are also used. Acicular mineral fillers are understood according to the invention as mineral fillers having a very pronounced acicular character. Acicular wollastonite is preferred. Preferably, the mineral has an aspect ratio of from 2:1 to 35:1, particularly preferably from 3:1 to 19:1, especially preferably from 4:1 to 12: 1. The mean particle size of the acicular mineral fillers used according to the invention as component B is preferably less than 20 μm, particularly preferably less than 15 μm, particularly preferably less than 10 μm, determined using a CILAS particle sizer.

Component B preferably used according to the invention is a reinforcing material. Which may here be a reinforcing material based on carbon and/or glass fibres, for example.

In a preferred embodiment, the fillers and/or reinforcing materials can be surface-modified, preferably with an adhesion promoter or an adhesion promoter system, particularly preferably based on silanes. In particular, in the case of glass fibers, it is possible to use polymer dispersions, film formers, branching agents (Verzweiger) and/or glass fiber processing aids in addition to silanes.

The glass fibers preferably used according to the invention as component B can be short glass fibers and/or long glass fibers. Chopped fibers may be used as the short glass fibers or the long glass fibers. Short glass fibers may also be used in the form of milled glass fibers. Furthermore, the glass fibers can additionally be used in the form of continuous fibers, for example in the form of rovings, monofilaments, filament yarns or twines, or in the form of a woven web, for example as a glass fabric, as a glass fabric or as a glass mat.

Typical fiber lengths of the short glass fibers before introduction into the polyamide matrix range from 0.05 to 10mm, preferably from 0.1 to 5 mm. After introduction into the polyamide matrix, the length of the glass fibers becomes smaller. Typical fiber lengths of the short glass fibers after incorporation in the polyamide matrix range from 0.01 to 2mm, preferably from 0.02 to 1 mm.

The diameter of the individual fibers can fluctuate within wide ranges. Typical diameters of the individual fibers range from 5 to 20 μm.

The glass fibers may have any cross-sectional shape, such as circular, elliptical, polygonal (n-eckig) or irregular cross-sections. Glass fibers having a cross-section that is either mono-lobal or multi-lobal may be used.

The glass fibers may be used as continuous fibers or as cut or milled glass fibers.

The glass fibers themselves are independent of their cross-sectional area and their length, and can in this case be selected, for example, from E-glass fibers, A-glass fibers, C-glass fibers, D-glass fibers, M-glass fibers, S-glass fibers, R-glass fibers and/or ECR-glass fibers, with E-glass fibers, R-glass fibers, S-glass fibers and ECR-glass fibers being particularly preferred. The glass fibers are preferably provided with a sizing material, which preferably comprises polyurethane as film former and aminosilane as adhesion promoter.

E-glass fibers having the following chemical composition are particularly preferably used: SiO 2₂50-56％； Al₂O₃12-16％；CaO 16-25％；MgO≤6％；B₂O₃6-13％；F≤0.7％；Na₂O 0.3-2％；K₂O 0.2-0.5％；Fe₂O₃0.3％。

The R-glass fibers used with particular preference have the following chemical composition: SiO 2₂50-65％；Al₂O₃20-30％；CaO 6-16％；MgO 5-20％；Na₂O 0.3-0.5％；K₂O 0.05-0.2％； Fe₂O₃0.2-0.4％；TiO₂0.1-0.3％。

The ECR glass fibers used with particular preference have the following chemical composition: SiO 2₂57.5-58.5％；Al₂O₃17.5-19.0％；CaO 11.5-13.0％；MgO 9.5-11.5。

The salts of diethylphosphinic acid used according to the invention as component C are known flame retardants for polymer molding materials.

The salts of diethylphosphinic acid which contain the phosphinic acid salts and phosphonate fractions used according to the invention as components D and E are likewise known flame retardants. The preparation of such a combination of substances is described, for example, in US 7,420,007B 2.

The salts of diethylphosphinic acid of component C used according to the invention may comprise small amounts of salts of component D and salts of component E, for example up to 10% by weight of component D, preferably from 0.01 to 6% by weight and in particular from 0.2 to 2.5% by weight, and up to 10% by weight of component E, preferably from 0.01 to 6% by weight and in particular from 0.2 to 2.5% by weight, based on the amounts of components C, D and E.

The salts of ethylphosphonic acid used according to the invention as component E are likewise known as additives to the diethylphosphinate salts in flame retardants for polymer molding compounds, for example from WO 2016/065971A 1.

The use of polyphosphate derivatives of melamine having a degree of condensation of greater than or equal to 20, which are used according to the invention as component F, as flame retardants is also known. Thus, DE 102005016195 a1 discloses stabilized flame retardants comprising 99 to 1% by weight of melamine polyphosphate and 1 to 99% by weight of additives having a reserve alkalinity. It is also disclosed in this document that the flame retardant can be combined with phosphinic acids and/or phosphinates.

Preferred flame retardant polyamide compositions according to the invention comprise as component F melamine polyphosphate having an average degree of condensation of from 20 to 200, in particular from 40 to 150.

A further preferred flame retardant polyamide composition according to the invention comprises as component F melamine polyphosphate having a decomposition temperature of greater than or equal to 320 ℃, in particular greater than or equal to 360 ℃ and very particularly preferably greater than or equal to 400 ℃.

Preferably, as component F, melamine polyphosphate is used, which is known from WO 2006/027340 a1 (corresponding to EP 1789475B 1) and WO 2000/002869a1 (corresponding to EP 1095030B 1).

Preference is given to using melamine polyphosphates having an average degree of condensation of between 20 and 200, in particular between 40 and 150, and a melamine content of from 1.1 to 2.0mol, in particular from 1.2 to 1.8mol, per mole of phosphorus atom.

Preference is likewise given to using melamine polyphosphates having an average degree of condensation (number average) of >20, a decomposition temperature of > 320 ℃, a molar ratio of 1,3, 5-triazine compound to phosphorus of less than 1.1, in particular from 0.8 to 1.0, and a 10% suspension in water having a pH of above 5, preferably from 5.1 to 6.9, at 25 ℃.

In another preferred embodiment, components C, D, E and F are present in particulate form, wherein the average particle size (d) is₅₀) Is 1 to 100 μm.

The sterically hindered phenols added as component G according to the invention are antioxidants known per se.

Preferred antioxidants used as component G are alkylated monophenols, for example 2, 6-di-tert-butyl-4-methylphenol or 2, 6-di-tert-butyl-4-methoxyphenol, sterically hindered alkylthiomethylphenols, for example 2, 4-dioctylthiomethyl-6-tert-butylphenol, sterically hindered hydroxylated thiodiphenyl ethers, for example 2,2' -thiobis (6-tert-butyl-4-methylphenol), 4' -thiobis- (6-tert-butyl-3-methylphenol), 4' -thiobis- (6-tert-butyl-2-methylphenol), 4' -thiobis- (3, 6-di-sec-amylphenol), 4' -bis- (2, 6-dimethyl-4-hydroxyphenyl) -disulfide, sterically hindered alkylene-bisphenols, for example 2,2' -methylene-bis- (6-tert-butyl-4-methylphenol, sterically hindered benzylphenols, for example 3,5,3',5' -tetra-tert-butyl-4, 4' -dihydroxybenzyl ether, for example 2,2' -methylene-bis- (6-tert-butyl-4-methylphenol), sterically hindered benzylphenols, 3, 5' -trimethylbenzenepropanoic acid, 3, 5-bis- (3, 5-di-tert-butyl-4-hydroxypropionyl) -2,3, 5-bis- (3, 5-di-tert-butyl-4-hydroxypropionyl) -2, 5-hydroxybenzyl) -2, 5-hydroxy-phenyl) -2,3, 5-tris (3, 5-di-tert-butyl-4-hydroxy-butyl-phenyl) -2, 6-tri-phenyl) -2, 5-tri (tert-butyl-4-butyl-methylpropionyl) -2,3, 6-tert-methylpropionyl-butyl-tert-butyl-hydroxy-4-butyl-methyl-hydroxy-butyl-phenyl) -2,3, 6-tert-butyl-tert-butyl-4-tri (3, 6-tert-butyl-tri (3-butyl-4-butyl-methyl-butyl-4-butyl-methyl-butyl-methyl-4-tert-butyl-methyl-propyl) -2-4-tert-butyl-phenyl) -2-butyl-methyl-4-butyl-three (3, 3-three (3-butyl-three (3-butyl-three (3-butyl) phenyl.

The organic phosphites and/or organophosphonites added according to the invention as component H are costabilizers for antioxidants known per se.

The organophosphites have the formula P (OR)₃Wherein R is a monovalent organic group.

The organic phosphonites have the general formula PR' (OR)₂Wherein R and R' are monovalent organic groups.

Examples of suitable organic phosphites are triaryl phosphites, diarylalkyl phosphites, aryldialkyl phosphites, trialkyl phosphites.

Examples of triarylphosphites are triphenyl phosphite, especially tris- (nonylphenyl) phosphite or tris (2, 4-di-tert-butylphenyl) phosphite.

Examples of diarylalkylphosphites are diphenylalkylphosphites, especially bis- (2, 4-di-tert-butyl-6-methylphenyl) methyl phosphite or bis (2, 4-di-tert-butyl-6-methylphenyl) ethyl phosphite.

An example of an aryl dialkyl phosphite is phenyl dialkyl phosphite.

An example of a trialkyl phosphite is C₁₂-C₁₈Trialkyl phosphites, especially trilauryl phosphite or trioctadecyl phosphite.

Further examples of suitable organophosphites are pentaerythritol diphosphites such as distearyl pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, diisodecyl oxypentaerythritol diphosphite, bis- (2, 4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite or bis- (2,4, 6-tris (tert-butylphenyl)) pentaerythritol diphosphite.

Further suitable organophosphites are tristearyl sorbitol triphosphite, 2',2 "-nitrilo- [ triethyl-tris (3,3',5,5' -tetra-tert-butyl-1, 1' -biphenyl-2, 2' -diyl) phosphite ] or 2-ethylhexyl- (3,3',5,5' -tetra-tert-butyl-1, 1' -biphenyl-2, 2' -diyl) phosphite.

Preferably, the organic phosphonites used according to the invention as component H are those of the formula IV

R₄-[P(OR₅)₂]_p(IV)

Wherein

R₄Is a mono-or polyhydric aliphatic, aromatic or heteroaromatic organic radical, and

R₅has a structure of formula (V)

Or two R₅The radicals forming a bridging group of the formula (VI)

Wherein

A represents a direct bond, O, S, straight or branched C_1-18Alkylene, straight-chain or branched C_1-18An alkylidene group (Alkyliden),

R₆independently of one another, represents a linear or branched C_1-12Alkyl, straight chainOr branched C_1-12-alkoxy and/or C_5-12-a cycloalkyl group,

q represents 0 to 5, and

p represents 1 to 4.

Phosphonites of the formula IV in which the radical R is present are preferably used as component H₄Is straight-chain or branched C_4-18Alkyl, straight or branched C_4-18Alkylene radical, C_5-12-cycloalkyl, C_5-12-cycloalkylene radical, C_6-24-aryl or C_6-24-heteroaryl, C_6-24Arylene or C_6-24-heteroarylene, which may optionally be additionally substituted, R₅The radical is of the formula (V) or (VI), R₆Independently of one another, straight-chain or branched C_1-8Alkyl, straight or branched C_1-8-alkoxy or cyclohexyl, A represents a direct bond, O, linear or branched C_1-8Alkylene, straight-chain or branched C_1-8-alkylidene, q is 0 to 3, and p is 1 to 3.

Particular preference is given to using phosphonites of the formula IV as component H, where the radical R₄Is cyclohexyl, phenyl, phenylene, biphenyl or biphenylene, R₅The group is of the formula V or VI, wherein R₆Independently of one another, represents a linear or branched C_1-8Alkyl, straight or branched C_1-8Alkoxy or cyclohexyl, A is a direct bond, O or C, linear or branched_1-6-alkylidene, q is 1 to 3, and p is 1 or 2.

Particularly preferred components H are compounds which are prepared on the basis of the above definition by Friedel-Crafts reaction of aromatic or heteroaromatic hydrocarbons, such as benzene, diphenyl ether or diphenyl ether, with phosphorus trihalides, preferably phosphorus trichloride, in the presence of Friedel-Crafts catalysts, such as aluminum chloride, zinc chloride or iron chloride, and then with phenols on which the residues of the formulae V or VI are based. Also specifically included herein are those mixtures with phosphites that result from excess phosphorus trihalide and the aforementioned phenols after the reaction sequence.

Also preferred from the group of organic phosphonites are compounds of the formula:

where n can be 0 or 1, and the mixture can optionally additionally comprise the following proportions of compounds:

a very particularly preferred component H is 1, 1-biphenyl-4, 4 '-diyl bisphosphinite and, in particular, tetrakis (2, 4-di-tert-butylphenyl) - [1, 1-biphenyl ] -4,4' -diyl bisphosphinite (P-EPQ).

N, N '-bis [3- (3', 5 '-di-tert-butyl-4' -hydroxyphenyl) propionyl group is particularly preferable]Hexamethylene diamine (e.g. hexamethylene diamine)1098, BASF) as component G and tris (2, 4-di-tert-butylphenyl) phosphite (for example168, BASF) was used as component H.

N, N '-bis [3- (3', 5 '-di-tert-butyl-4' -hydroxyphenyl) propionyl group is particularly preferable]Hexamethylene diamine (e.g. hexamethylene diamine)1098, BASF) as component G and tetrakis (2, 4-di-tert-butylphenyl) - [1, 1-biphenyl]4,4' -diyl bisphosphonites (e.g. bisphenol A)P-EPQ, Clariant) was used as component H.

The polyamide composition according to the invention may also comprise further additives as component J. Preferred components J in the sense of the present invention are further antioxidants which are not sterically hindered phenols, UV-stabilizers, gamma stabilizers, hydrolysis stabilizers, co-stabilizers of antioxidants which are not organophosphites, antistatic agents, emulsifiers, nucleating agents, plasticizers, processing aids, impact modifiers, dyes, pigments and/or further flame retardants which differ from components C, D, E, F and I.

The further additives are known per se as additives for polyamide compositions and can be used individually or in the form of mixtures or in the form of masterbatches.

The aforementioned component A, B, C, D, E, F, G, H and optional I and/or J can be processed in various combinations into flame retardant polyamide compositions according to the present invention. It is thus possible to mix the components into the polyamide melt already at the beginning of the polycondensation or at the end thereof or during the subsequent compounding. Furthermore, there are processes in which the individual components are added only later. This is especially practiced where pigment masterbatches or additive masterbatches are used. Furthermore, there is the possibility of drum processing the pulverulent components, in particular, onto polymer pellets which may be hot by the drying process.

It is also possible to combine two or more components of the polyamide composition according to the invention by mixing before introduction into the polyamide matrix. In this case, conventional mixing equipment can be used, in which the components are mixed in a suitable mixer, for example at from 0 to 300 ℃ for from 0.01 to 10 hours.

It is also possible to prepare pellets from two or more components of the polyamide composition according to the invention, which pellets can subsequently be introduced into the polyamide matrix.

To this end, two or more components of the polyamide composition according to the invention can be processed into pellets with granulation auxiliaries and/or binders in suitable mixers or pan granulators.

The first-produced crude product can be dried in a suitable dryer or tempered to form other particle structures.

The polyamide composition according to the invention or two or more components thereof may in one embodiment be prepared by roll compaction.

The polyamide composition according to the invention or two or more components thereof may in one embodiment be prepared therefrom: the ingredients are mixed, strand extruded, pelletized (or optionally crushed and classified) and dried (and optionally coated).

The polyamide composition according to the invention or two or more components thereof may in one embodiment be prepared by spray granulation.

The flame-retardant polymer molding compositions according to the invention are preferably present in the form of pellets, for example as extrudates or as compounds. The pellets are preferably cylindrical, spherical, pillow-shaped, cubic, oblong, prismatic in shape with a circular, oval or irregular base.

Typical aspect ratios of the pellets are from 1 to 50 to 1, preferably from 1 to 5 to 1.

The pellets preferably have a diameter of from 0.5 to 15mm, particularly preferably from 2 to 3mm, and a length of from 0.5 to 15mm, particularly preferably from 2 to 5 mm.

The subject of the invention is also moldings produced from the abovementioned flame retardant polyamide compositions comprising components A, B, C, D, E, F, G and H and optionally components I and/or J.

The moulded article according to the invention can be of any form. Examples of these are fibers, films or moldings which can be obtained from the flame-retardant polyamide molding compounds according to the invention by any shaping process, in particular by injection molding or extrusion.

The production of the flame-retardant polyamide molded articles according to the invention can be carried out by any shaping method. Examples of this are injection molding, pressing, foam injection molding, internal gas pressure injection molding, blow molding, film casting, calendering, laminating or coating with flame-retardant polyamide molding compounds at higher temperatures.

The molded part is preferably an injection molded part or an extrusion molded part.

The flame-retardant polyamide compositions according to the invention are suitable for the production of fibers, films and moldings, in particular for applications in the electrical and electronic fields.

The present invention preferably relates to the use of the flame retardant polyamide composition according to the invention in or for the following items: connectors, energized components in power distributors (FI protection), circuit boards, potting material, power plugs, safety switches, lamp housings, LED housings, capacitor housings, coil form and fans, protection contacts, plugs, in/on circuit boards, housings for plugs, cables, flexible printed circuit boards, charger connection lines for mobile phones, engine covers or textile coatings.

The invention likewise preferably relates to the use of the flame-retardant polyamide compositions according to the invention for producing moldings in the form of parts for the electrical/electronic sector, in particular for parts of printed circuit boards, housings, films, wires, switches, distributors, relays, resistors, capacitors, coils, lamps, diodes, LEDs, transistors, connectors, regulators, memories and sensors, in the form of large-area parts, in particular housing parts for switch cabinets and in the form of parts of complex design having a critical geometry.

The wall thickness of the moldings according to the invention may typically be up to 10 mm. Particularly suitable are moldings having a wall thickness of less than 1.5mm, more preferably less than 1mm and particularly preferably less than 0.5 mm.

Detailed Description

The following examples illustrate the invention without limiting it.

1. The components used

Commercial polyamide (component a):

polyamide 6,6(PA 6, 6-GV; melting range 255-:A27(BASF)

polyamide 6 (melting range 217 ℃ C.):B29(Lanxess)

polyamide 6T/6,6 (melting range 310-320 ℃):HAT plus 1000 (Evonik)

glass fibers (component B):

glass fiber PPG HP3610, 10 μm diameter, 4.5mm length (PPG company, NL),

flame retardant FM 1 (components C, D and E):

aluminium salt of diethylphosphinic acid, containing 0.9 mol% of ethylbutylphosphinic acid aluminium and 0.5 mol% of ethylphosphinic acid aluminium, prepared according to example 3 of US 7,420,007B2

Flame retardant FM 2 (components C, D and E):

aluminium salt of diethylphosphinic acid, containing 2.7 mol% of ethylbutylphosphinic acid aluminium and 0.8 mol% of ethylphosphinic acid aluminium, prepared according to example 4 of US 7,420,007B2

Flame retardant FM 3 (components C, D and E):

aluminium salt of diethylphosphinic acid, containing 0.5 mol% of ethylbutylphosphinic acid aluminium and 0.05 mol% of ethylphosphinic acid aluminium, prepared according to the method of US 7,420,007B2

Flame retardant FM 4 (components C, D and E):

aluminium salt of diethylphosphinic acid, containing 10 mol% of aluminium ethylbutylphosphinate and 5 mol% of aluminium ethylphosphinate, prepared according to the method of US 7,420,007B2

Flame retardant FM 5 (component C):

aluminium salt of diethylphosphinic acid, preparation analogous to example 1 of DE 19607635A 1

Flame retardant FM 6 (components C and E):

aluminium salt of diethylphosphinic acid, containing 8.8 mol% of aluminium ethylphosphonate

Flame retardant FM 7 (component I):

aluminium salts of phosphonic acids, prepared according to DE 102011120216A 1, example 1

Flame retardant FM 8 (component F):

melamine polyphosphate, prepared according to the examples of WO 2000/002869A1

Flame retardant FM 9 (not according to the invention):

melamine polyphosphate, having an average degree of condensation of 18, prepared analogously to WO 2000/002869A1

Antioxidant (component G)

N, N '-bis [3- (3', 5 '-di-tert-butyl-4' -hydroxyphenyl) propionyl group]Hexamethylene diamine (b)1098，BASF)

Co-stabilizer H1 (component H)

Tris (2, 4-di-tert-butylphenyl) phosphite168，BASF)

Co-stabilizer H2 (component H)

Tetrakis (2, 4-di-tert-butylphenyl) - [1, 1-biphenyl]4,4' -diyl bisphosphinite(s) ((s))P-EPQ，Clariant)

2. Preparation, working and testing of flame-retardant Polyamide moulding Compounds

The flame retardant components were mixed in the proportions given in the table with antioxidants and with co-stabilizers and fed to PA6,6 at a temperature of from 260 to 310 ℃ or to PA6 at a temperature of from 250 to 275 ℃ or to PA 6T/6,6 at a temperature of from 310 to 330 ℃ via the side feed opening of a twin-screw extruder (model: Leistritz ZSE 27/44D). Glass fibers were added through the second side feed inlet. The homogenized polymer strand was drawn off, cooled in a water bath and subsequently pelletized.

After sufficient drying, the moulding compositions were processed on an injection moulding machine (model: Arburg 320℃ Allrounder) at a batch temperature of 250 to 320 ℃ to give test pieces and tested for fire resistance by means of the UL94 test (Underwriter Laboratories) and classified. In addition to the classification, the afterflame time is also given.

The flowability of the moulding compositions was determined by determining the melt volume index at 275 ℃ C./2.16 kg. A higher MVR value means better flowability during injection molding. However, a large increase in MVR value may also suggest polymer degradation.

The relative tracking index of the moulded article is determined according to the international electrotechnical commission standard IEC-60112/3.

The glow wire flammability index (GWFI index) is determined according to the standard IEC-60695-2-12.

The color of the molded article was visually evaluated.

Unless otherwise stated, all tests of each series were performed under the same conditions (such as temperature program, screw geometry and injection molding parameters) for comparability.

Examples 1-6, 1a, 1b, 5a and comparative examples V1-V8, using PA6,6

The results of the tests with the PA6,6 molding compound are set forth in the examples cited in Table 1 below. All amounts are given in% by weight and are based on the polyamide moulding compound including flame retardants, additives and reinforcing materials.

The polyamide compositions according to the invention of examples 1 to 6, 1a, 1b and 5a are moulding compositions which achieve a fire rating of UL-94V-0 at 0.4mm, at the same time have a CTI of 600 volts and a GWFI of 960 ℃ and exhibit no discoloration. The addition of component I in examples 5 and 5a leads to a further improvement in the flame retardancy exhibited by the shortened afterflame times.

The omission of components D and E in comparative example V1, in addition to the extended after-flame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 1 to 4.

The omission of component D in comparative example V2, in addition to the extended after-flame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 1 to 4.

The replacement of component F by a component with a lower degree of condensation in comparative example V3 resulted in the polyamide strand being foamed during production and no measurement being possible.

The omission of component F in comparative example V4 results in an increased MVR value and a reduced GWFI value in addition to the deterioration of the fire rating compared to example 2.

In comparative example V5, an improvement in the fire rating is achieved compared with example V4 by increasing the concentration of components C, D and E. However the polyamide composition still consistently showed lower fire rating and increased MVR value and reduced GWFI value compared to example 2.

In the case of comparative example V6, in which component H was omitted, an elevated MVR value was found in comparison with example 2.

In the case of comparative example V7, in which component G was omitted, an increased MVR value and reduced CTI and GWFI values were determined in comparison with example 2. In addition, the moldings discolored significantly during production.

In the case of comparative example V8, in which components G and H were omitted, distinctly increased MVR values and also reduced CTI values were determined in comparison with example 2. Furthermore, the moldings here also discolor significantly during production.

Examples 7 to 12 and comparative examples V9 to V16, using PA6

The results of the tests with the PA6 molding compounds are listed in the examples cited in the table below. All amounts are given in% by weight and are based on the polyamide moulding compound including flame retardants, additives and reinforcing materials.

The polyamide compositions according to the invention of examples 7 to 12 are moulding compositions which achieve a fire rating of UL-94V-0 at 0.4mm, at the same time have a CTI of 600 volts and a GWFI of 960 ℃ and exhibit no discoloration. The addition of component I in example 11 results in a further improvement in the flame retardancy exhibited by the shortened afterflame time.

The omission of components D and E in comparative example V9, in addition to the extended afterflame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 7 to 10.

The omission of component D in comparative example V10, in addition to the extended after-flame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 7 to 10.

The replacement of component F by a component with a lower degree of condensation in comparative example V11 resulted in the polyamide strand being foamed during production and no measurement being possible.

The omission of component F in comparative example V12 results in an increased MVR value and a reduced GWFI value in addition to the deterioration of the fire rating compared to example 8.

In comparative example V13, an improvement in the fire rating is achieved compared with example V12 by increasing the concentration of components C, D and E. However the polyamide composition still consistently showed lower fire rating and increased MVR value and reduced GWFI value compared to example 8.

In the case of comparative example V14, in which component H was omitted, a distinctly increased MVR value was found in comparison with example 8.

In the case of comparative example V15, in which component G was omitted, an increased MVR value and reduced CTI and GWFI values were determined in comparison with example 8. In addition, the moldings discolored significantly during production.

In the case of comparative example V16, in which components G and H were omitted, an increased MVR value and a reduced CTI value were determined in comparison with example 8. Furthermore, the moldings here also discolor significantly during production.

Examples 13 to 18 and comparative examples V17 to V24, using PA6, 6/PA6

The results of the tests with the PA 6/PA6,6 molding compound are set forth in the examples cited in the table below. All amounts are given in% by weight and are based on the polyamide moulding compound including flame retardants, additives and reinforcing materials.

The polyamide compositions according to the invention of examples 13 to 18 are moulding compositions which achieve a fire rating of UL-94V-0 at 0.4mm, at the same time have a CTI of 600 volts and a GWFI of 960 ℃ and exhibit no discoloration. The addition of component I in example 17 results in a further improvement in the flame retardancy exhibited by the shortened afterflame time.

The omission of components D and E in comparative example V17, in addition to the extended after-flame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 13 to 16.

The omission of component D in comparative example V18, in addition to the extended after-flame time, also leads to an increased MVR value and a reduction in the CTI value in comparison with examples 13 to 16.

The replacement of component F by a component with a lower degree of condensation in comparative example V19 resulted in the polyamide strand being foamed during production and no measurement being possible.

The omission of component F in comparative example V20 results in an increased MVR value and a reduced GWFI value in addition to the deterioration of the fire rating compared to example 14.

In comparative example V21, an improvement in the fire rating is achieved compared with example V20 by increasing the concentration of components C, D and E. However the polyamide composition still consistently showed lower fire rating and increased MVR value and reduced GWFI value compared to example 14.

In the case of comparative example V22, in which component H was omitted, a distinctly increased MVR value was found in comparison with example 14.

In the case of comparative example V23, in which component G was omitted, significantly increased MVR values and reduced CTI and GWFI values were determined in comparison with example 14. In addition, the moldings discolored significantly during production.

In the case of comparative example V24, in which components G and H were omitted, distinctly increased MVR values and reduced CTI values were determined in comparison with example 14. Furthermore, the moldings here also discolor significantly during production.

Comparative examples V25-V31, using PA 6T/6,6

The results of the tests with the PA 6T/6,6 molding compound are set forth in the examples cited in the table below. All amounts are given in% by weight and are based on the polyamide moulding compound including flame retardants, additives and reinforcing materials.

Table 4: PA 6T/6,6GF 30 test results (n.b. ═ not determined)

Example numbering	V25	V26	V27	V28	V29	V31	V32
								A: polyamide 6T/6,6	52.8	52.8	52.8	52.8	52.8	52.8	52.8
B: glass fiber HP3610	30	30	30	30	30	30	30
								C+D+E：FM 1	-	-	12	-	-	-	-
C+D+E：FM 2	-	-	-	12	-	-	10
								C+D+E：FM 3	-	-	-	-	12	-	-
C+D+E：FM 4	-	-	-	-	-	12	-
								C：FM 5	12	-	-	-	-	-	-
C+E：FM 6	-	12	-	-	-	-	-
								I：FM 7	-	-	-	-	-	-	2
F：FM 8	5	5	5	5	5	5	5
								And (3) comparison: FM 9	-	-	-	-	-	-	-
G: antioxidant agent	0.1	0.	0.1	0.1	0.1	0.1	0.1
								H1: co-stabilizer	0.1	0.1	0.1	0.1	0.1	0.1	0.1
UL 940.4 mm/time [ sec ]]	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.
								GWFI[℃]	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.
MVR[cm3/10min.]	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.
								Colour(s)	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.
CTI [ volt ]]	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.	n.b.

No test pieces could be produced from the PA molding compounds of comparative examples V25 to V32, since the PA molding compounds proved to be impossible to process. The polyamide strands foamed during the production and no test pieces suitable for the measurement could be produced.

Claims (23)

1. Flame retardant polyamide composition comprising

A polyamide as component A having a melting point of less than or equal to 290 ℃,

as component B, fillers and/or reinforcements,

phosphinic acid salts of the formula (I) as component C

Wherein R is₁And R₂Represents an ethyl group, and represents a linear or branched alkyl group,

m is Al, Fe, TiO_pOr a combination of Zn and a metal selected from the group consisting of,

m represents 2 to 3, and

p＝(4–m)/2，

-as component D a compound selected from: al, Fe, TiO salts of ethylbutylphosphinic acid, dibutylphosphinic acid, ethylhexylphosphinic acid, butylhexylphosphinic acid and/or dihexylphosphinic acid_pA salt or a Zn salt, wherein the Zn salt is a zinc salt,

phosphonates of the formula II as component E

Wherein R is₃Represents an ethyl group, and represents a linear or branched alkyl group,

met is Al, Fe, TiO_qOr a combination of Zn and a metal selected from the group consisting of,

n represents 2 to 3, and

q＝(4–n)/2，

melamine polyphosphate having an average degree of condensation greater than or equal to 20 as component F,

as component G, a sterically hindered phenolic antioxidant, and/or

Organic phosphites and/or organic phosphonites as component H.

2. Flame retardant polyamide composition according to claim 1, characterized in that M and Met denote Al, M and n are 3, and component D is an aluminium salt.

3. Flame retardant polyamide composition according to at least one of claims 1 to 2, characterized in that,

the proportion of component A is from 25 to 95% by weight,

the proportion of component B is from 1 to 45% by weight,

the proportion of component C is from 1 to 35% by weight,

the proportion of component D is from 0.01 to 3% by weight,

the proportion of component E is from 0.001 to 1% by weight,

the proportion of component F is from 1 to 25% by weight,

the proportion of component G is from 0.05 to 5% by weight, and

the proportion of component H is from 0.05 to 5% by weight

Wherein the percentage values are based on the total amount of the polyamide composition.

4. A flame retardant polyamide composition according to claim 3,

the proportion of component A is from 25 to 75% by weight,

the proportion of component B is from 20 to 40% by weight,

the proportion of component C is from 5 to 20% by weight,

the proportion of component D is from 0.05 to 1.5% by weight,

the proportion of component E is from 0.01 to 0.6% by weight,

the proportion of component F is from 2 to 10% by weight,

the proportion of component G is from 0.1 to 1% by weight, and

the proportion of component H is from 0.1 to 1% by weight.

5. Flame retardant polyamide composition according to at least one of claims 1 to 4, characterized in that the polyamide composition comprises an inorganic phosphonate as further component I.

6. The flame retardant polyamide composition of claim 5, wherein the inorganic phosphonate is a compound of formula (III)

Wherein Me is Fe and TiO_rZn or, in particular, Al,

o represents 2 to 3, preferably 2 or 3, and

r＝(4–o)/2，

wherein the compound of formula III is present in an amount of 0.005 to 10% by weight, especially 0.02 to 5% by weight, based on the total amount of the polyamide composition.

7. Flame retardant polyamide composition according to at least one of claims 1 to 6, characterized in that the composition has a relative tracking index measured according to the International electrotechnical Commission Standard IEC-60112/3 of more than 500 volts.

8. Flame retardant polyamide composition according to at least one of claims 1 to 7, characterized in that the composition achieves a V0 rating according to UL-94 of 3.2mm to 0.4mm thickness.

9. Flame retardant polyamide composition according to at least one of claims 1 to 8, characterized in that the composition has a glow wire flammability index according to IEC-60695-2-12 of at least 960 ℃ at a thickness of 0.75-3 mm.

10. Flame retardant polyamide composition according to at least one of claims 1 to 9, characterized in that component a is one or more polyamides selected from the group consisting of PA6, PA 4,6, PA 12, PA6, 10.

11. Flame retardant polyamide composition according to claim 10, characterized in that component a is polyamide 6,6 or a polymer mixture of polyamide 6,6 and polyamide 6.

12. Flame retardant polyamide composition according to claim 11, characterized in that component a consists of at least 75% by weight of polyamide 6,6 and at most 25% by weight of polyamide 6.

13. Flame retardant polyamide composition according to at least one of claims 1 to 12, characterized in that glass fibers are used as component B.

14. Flame retardant polyamide composition according to at least one of claims 1 to 13, characterized in that components C, D, E and F are present in particulate form, wherein the components have an average particle size d₅₀Is 1 to 100 μm.

15. Flame retardant polyamide composition according to at least one of claims 1 to 14, characterized in that the average degree of condensation of the melamine polyphosphate is from 20 to 200.

16. Flame retardant polyamide composition according to at least one of claims 1 to 15, characterized in that the melamine polyphosphate has a decomposition temperature of greater than or equal to 320 ℃.

17. Flame retardant polyamide composition according to at least one of claims 1 to 16, characterized in that component G is selected from the group consisting of alkylated monophenols, sterically hindered alkylthiomethylphenols, sterically hindered hydroxylated thiodiphenyl ethers, sterically hindered alkylidenebisphenols, sterically hindered benzylphenols, sterically hindered hydroxybenzylated malonates, sterically hindered hydroxybenzylaromatic hydrocarbons, sterically hindered phenolic triazine compounds, sterically hindered phenolic benzylphosphonates, alkyl N- (3, 5-di-tert-butyl-4-hydroxyphenyl) -carbamates, esters of β - (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionic acid with monohydric or polyhydric alcohols, esters of β - (5-tert-butyl-4-hydroxy-3-methylphenyl) -propionic acid with monohydric or polyhydric alcohols, esters of β - (3, 5-dicyclohexyl-4-hydroxyphenyl) -propionic acid with monohydric or polyhydric alcohols, esters of 3, 5-di-tert-butyl-4-hydroxyphenyl acetic acid with monohydric or polyhydric alcohols or amides of β - (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionic acid.

18. Flame retardant polyamide composition according to at least one of claims 1 to 17, characterized in that component H is a triarylphosphite, especially tris (2, 4-di-tert-butylphenyl) -phosphite.

19. The flame retardant polyamide composition of claim 18 wherein component G is N, N '-bis [3- (3', 5 'di-tert-butyl-4' -hydroxyphenyl) propionyl ] -hexamethylenediamine and component H is tris (2, 4-di-tert-butylphenyl) phosphite.

20. Flame retardant polyamide composition according to at least one of claims 1 to 17, characterized in that component H is 1, 1-biphenyl-4, 4 '-diyl bisphosphonite, in particular tetrakis (2, 4-di-tert-butylphenyl) - [1, 1-biphenyl ] -4,4' -diyl bisphosphonite.

21. Flame retardant polyamide composition according to claim 20, characterized in that component G is N, N ' -bis [3- (3 ',5' -di-tert-butyl-4 ' -hydroxyphenyl) propionyl ] -hexamethylenediamine and component H is tetrakis (2, 4-di-tert-butylphenyl) - [1, 1-biphenyl ] -4,4' -diyl bisphosphinite.

22. Flame retardant polyamide composition according to at least one of claims 1 to 21, characterized in that the composition comprises as component J a further additive, wherein the further additive is selected from the group consisting of further antioxidants which are not sterically hindered phenols, UV-stabilizers, gamma-ray stabilizers, hydrolytic stabilizers, co-stabilizers of antioxidants which are not organophosphites, antistatic agents, emulsifiers, nucleating agents, plasticizers, processing aids, impact modifiers, dyes, pigments and/or further flame retardants different from components C, D, E and F.

23. Use of a polyamide composition according to any one of claims 1 to 22 for the preparation of fibres, films and mouldings, especially for applications in the electrical and electronic fields.