Flame retardant polymer composition and articles made therefrom

Abstract

A halogen-free flame retardant polymer composition is disclosed. The polymer composition comprises a thermoplastic polymer, such as polybutylene terephthalate. The thermoplastic polymer is combined with a flame retardant, which comprises a phosphinate, a phosphite and a nitrogen-containing synergist. In addition, the composition may contain a fluorine-containing polymer and an organic metal compatibilizer. Even if the flame retardant composition contains a thermoplastic polymer in an amount greater than 60 wt %, the flame retardant composition exhibits excellent flame retardancy.

Description

[0001] Related Applications

[0002] This application is based upon and claims the benefit of U.S. Provisional Application Serial No. 62 / 868,061, filed on June 28, 2019, which is incorporated herein by reference. Background Art

[0003] Engineering thermoplastics and elastomeric materials are commonly used in a variety of different applications to produce molded parts and molded articles. For example, polyester polymers and polyester elastomers are used to produce all different types of molded articles, such as injection molded articles, blow molded articles, etc. For example, polyester polymers can be formulated to have chemical resistance, excellent strength properties, and flexibility when the composition containing the polyester elastomer is formulated. It is particularly advantageous that polyester polymers can be melt processed due to their thermoplastic properties. In addition, polyester polymers can be recycled and reprocessed.

[0004] One problem faced by those skilled in the art when producing molded parts and molded articles from thermoplastic polymers is the ability to render the articles flame retardant. Although an almost unlimited variety of different flame retardants are commercially available and sold, selecting the appropriate flame retardant for a particular thermoplastic polymer composition is difficult and unpredictable. In addition, many of the available flame retardants contain halogen compounds, such as bromine compounds, which generate irritating chemical gases during the production process.

[0005] In view of the above, various halogen-free flame retardants have been developed and tested. In particular, various different phosphorus compounds have been used as flame retardants in thermoplastic polymer compositions. However, in order to meet certain requirements, phosphorus compounds are usually combined with many other different additives, such as other polymers and fillers. However, phosphorus-based flame retardant packages tend to severely and adversely affect the physical properties of polymers, including the ability to melt process polymers. In addition, many flame retardant packages do not provide sufficient flame retardancy for many applications.

[0006] In view of the above, there is a need for a halogen-free flame retardant composition that can be used with thermoplastic polymers. There is also a need for a flame retardant composition for thermoplastic polymers that maintains various polymer properties, such as maintaining flow properties. Summary of the invention

[0007] In general, the present disclosure relates to a polymer composition comprising a thermoplastic polymer and a flame retardant composition. The components of the flame retardant composition are carefully selected to produce a polymer composition with improved fire resistance. For example, when tested according to Underwriters Laboratories Test 94, the polymer composition can show a V-0 rating even at a thickness of 0.4 mm. In addition, the components of the flame retardant composition are also selected to maintain the various physical properties of the polymer composition.

[0008] For example, in one embodiment, the present disclosure relates to a flame retardant polymer composition comprising a thermoplastic polymer. The thermoplastic polymer can be present in the polymer composition in an amount greater than about 40wt%, for example, in an amount greater than about 60wt%, for example, in an amount greater than about 65wt%, for example, in an amount greater than about 70wt%, for example, in an amount greater than about 75wt%. Any suitable thermoplastic polymer can be used in the polymer composition of the present disclosure, such as polyolefins, polyamides and polyester polymers. However, the flame retardant composition of the present disclosure is particularly suitable for blending with polyester polymers such as polybutylene terephthalate.

[0009] According to the present disclosure, a thermoplastic polymer is combined with a flame retardant composition comprising a combination of a metal phosphite, a metal phosphite and a nitrogen-containing synergist. For example, the metal phosphite may include aluminum phosphite having the formula: Al2(HPO3)3. On the other hand, the metal phosphite may be a dialkyl phosphite, such as aluminum diethylphosphinate. The nitrogen-containing synergist may include melamine, such as melamine cyanurate. In one aspect, the metal phosphite is present in the polymer composition in an amount of about 5wt% to about 30wt%, such as about 10wt% to about 25wt%, such as about 12wt% to about 19wt%. The metal phosphite may typically be present in the polymer composition in an amount of about 0.5wt% to about 9wt%, such as about 1wt% to about 7wt%, such as about 2wt% to about 5wt%. In another aspect, the nitrogen-containing synergist can generally be present in the polymer composition in an amount from about 0.01 wt% to about 7 wt%, such as from about 0.3 wt% to about 4 wt%, such as from about 0.5 wt% to about 2.3 wt%.

[0010] The flame retardant polymer composition may also contain polytetrafluoroethylene. The polytetrafluoroethylene may be present in the polymer composition in an amount of, for example, about 0.1 wt % to about 5 wt %.

[0011] The flame retardant polymer composition may also include an organic metal compatibilizer. The organic metal compatibilizer may be, for example, a titanate. An example of an available titanate is 2-propanolato tris(dioctyl)phosphato-O titanium (IV) (titanium IV 2-propanolato, tris(dioctyl)phosphato-O). The organic metal compatibilizer may typically be present in the polymer composition in an amount of about 0.05 wt% to about 2.5 wt%. The flame retardant polymer composition may also include an ester of a carboxylic acid. For example, the ester may be formed by reacting montanic acid with a polyfunctional alcohol. The polyfunctional alcohol may be ethylene glycol or glycerol. The ester of a carboxylic acid may typically be present in the polymer composition in an amount of about 0.05 wt% to about 8 wt%. In one aspect, the flame retardant polymer composition may be configured so that it does not contain metal oxides, metal hydroxides, metal borates, and metal stannates. In the past, these components were typically used as flame retardant adjuvants and were taught to be necessary in many formulations. However, it has been found that eliminating one or more of the above components produces a polymer composition with better physical properties (including flow properties).

[0012] For example, the flame retardant polymer composition of the present disclosure may have a thermal conductivity of at least 4 cm when tested at 250° C. and a load of 2.16 kg. 3 / 10min, for example, greater than about 5cm 3 / 10min, for example, greater than about 10cm 3 / 10min melt flow rate. In the past, the addition of phosphorus-based flame retardant packages to thermoplastic polymers tended to significantly adversely affect the flow properties of the polymer. Therefore, in the past, in order to be able to measure the melt flow index, the melt flow rate was tested at 275°C. However, the flame retardant polymer composition of the present disclosure can be formulated and can show sufficient flow properties at lower temperatures, such as 250°C.

[0013] Other features and aspects of the disclosure are discussed in greater detail below. DETAILED DESCRIPTION

[0014] Those of ordinary skill in the art will appreciate that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present disclosure.

[0015] In general, the present disclosure relates to a halogen-free flame retardant polymer composition. The polymer composition prepared according to the present disclosure not only exhibits excellent flammability ratings when tested according to the American Insurance Laboratory Test, but also has excellent mechanical properties, including polymer processability. The flame retardant composition in combination with a thermoplastic polymer according to the present disclosure includes selected components that have been found to act synergistically. The flame retardant composition can also be formulated so that various flame retardant adjuvants used in the past can be excluded without compromising the flame retardant properties of the polymer composition. In fact, it has been found that excluding certain components to maintain various physical properties of the composition, such as the melt flow characteristics of the composition.

[0016] Typically, the flame retardant polymer composition of the present disclosure comprises a suitable thermoplastic polymer, such as polybutylene terephthalate, in combination with a flame retardant composition containing a metal phosphinate, a metal phosphite and a nitrogen-containing synergist. In addition, the composition may contain a fluoropolymer, such as polytetrafluoroethylene. The flame retardant polymer composition may also include an organometallic compatibilizer. The organometallic compatibilizer is believed to not only improve the flame retardant properties of the composition, but also significantly and unexpectedly improve the flow properties of the polymer composition when heated.

[0017] The flame retardant polymer composition of the present disclosure can also be formulated without various flame retardant adjuvants used in the past. For example, the flame retardant polymer composition of the present disclosure can be formulated without metal oxides, metal hydroxides, metal borates and / or metal stannates. For example, the flame retardant polymer composition of the present disclosure, on the one hand, can be formulated without the following: magnesium oxide, calcium oxide, aluminum oxide, zinc oxide, manganese oxide, tin oxide, aluminum hydroxide, boehmite, magnesium dialuminate, hydroceramite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, tin oxide hydrate, manganese hydroxide, zinc borate, basic zinc silicate or zinc stannate. It was believed in the past that one of the above components was needed in certain applications to obtain a lower flammability grade. However, the above fillers can interfere with the various physical properties of the polymer composition.

[0018] As mentioned above, the polymer composition generally comprises a thermoplastic polymer. Generally, any suitable thermoplastic polymer can be used. The thermoplastic polymer can be, for example, a polyamide, a polyolefin such as an ethylene polymer or a propylene polymer, a polyester polymer, a polycarbonate polymer, etc. However, the flame retardant composition of the present disclosure is particularly suitable for use with a polyester polymer.

[0019] The polyesters suitable for use herein are derived from aliphatic or cycloaliphatic diols or mixtures thereof containing from 2 to about 10 carbon atoms and aromatic dicarboxylic acids, ie, polyalkylene terephthalates.

[0020] Polyesters derived from cycloaliphatic diols and aromatic dicarboxylic acids are prepared by condensing, for example, the cis or trans isomers of 1,4-cyclohexanedimethanol (or mixtures thereof) with an aromatic dicarboxylic acid.

[0021] Examples of aromatic dicarboxylic acids include isophthalic acid or terephthalic acid, 1,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether, and the like, and mixtures thereof. All of these acids contain at least one aromatic nucleus. Condensed rings may also be present in, for example, 1,4- or 1,5- or 2,6-naphthalene dicarboxylic acids. In one embodiment, the dicarboxylic acid is terephthalic acid or a mixture of terephthalic acid and isophthalic acid.

[0022] Polyesters that can be used in the polymer composition include, for example, polyethylene terephthalate, polybutylene terephthalate, mixtures thereof, and copolymers thereof.

[0023] Thermoplastic polymers such as polybutylene terephthalate polymers are present in the polymer composition in an amount sufficient to form a continuous phase. For example, the thermoplastic polymer can be present in the polymer composition in an amount of at least about 40wt%, for example, in an amount of at least about 60wt%, for example, in an amount of at least about 65wt%, for example, in an amount of at least about 70wt%, for example, at least about 75wt%, for example, at least about 80wt%. Thermoplastic polymers are usually present in an amount less than about 97wt%.

[0024] According to the present disclosure, at least one thermoplastic polymer as described above is combined with a flame retardant composition according to the present disclosure. The flame retardant composition contains a metal phosphinate, a metal phosphite and a nitrogen-containing synergist.

[0025] For example, the metal phosphinate can be a dialkyl phosphinate and / or a diphosphinate. The metal phosphinate can have one of the following chemical structures:

[0026]

[0027] Where R 1 , R 2 are identical or different and are each a linear or branched C1-C6-alkyl group; R 3 Is a straight chain or branched C1-C 10 -alkylene, C6-C 10 -Arylene, C7-C 20 -alkylarylene or C7-C 20 -arylalkylene; M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K and / or a protonated nitrogen base; m is 1 to 4; n is 1 to 4; x is 1 to 4.

[0028] In one embodiment, the metal phosphinate is a metal dialkyl phosphinate, such as aluminum diethyl phosphinate. The metal phosphinate can be generally greater than about 5wt% in an amount, such as greater than about 10wt%, such as greater than about 15wt%, such as greater than about 20wt% and generally less than about 25wt%, such as less than about 22wt%, such as less than about 19wt%, such as less than about 17wt%, such as less than about 14wt% in an amount present in the polymer composition. In one embodiment, the metal phosphinate is present in the polymer composition in an amount of about 12wt% to about 19wt%.

[0029] The metal phosphite present in the polymer composition can be any suitable metal phosphite made from any of the metals (M) described above. In one aspect, the metal phosphite is aluminum phosphite. The aluminum phosphite can have the following chemical structure: Al2(HPO3)3. Other forms of aluminum phosphite can also be present in the polymer composition. Such other forms include basic aluminum phosphite, aluminum phosphite tetrahydrate, etc. In yet another embodiment, the aluminum phosphite can have the following formula: Al(H2PO3)3.

[0030] The metal phosphite is believed to act synergistically with the metal phosphinate to improve the flame retardant properties of the polymer composition, especially when the polymer composition contains polybutylene terephthalate. The weight ratio between the metal phosphinate and the metal phosphite can generally be from about 10:8 to about 30:1, such as from about 10:1 to about 20:1, such as from about 14:1 to about 18:1. In one aspect, the metal phosphite can be present in the polymer composition in an amount greater than about 0.5 wt%, such as in an amount greater than about 1 wt%, such as in an amount greater than about 1.5 wt%, such as in an amount greater than about 2 wt%, and typically in an amount less than about 10 wt%, such as in an amount less than about 7 wt%, such as in an amount less than about 5 wt%, such as in an amount less than about 3 wt%.

[0031] The nitrogen-containing synergist present in combination with the metal phosphinate and the metal phosphite may include melamine. For example, the nitrogen-containing synergist may include melamine cyanurate. Other melamine compounds that may be used include polyphosphate melamine, dimelamine polyphosphate, melem polyphosphate, melon polyphosphate, melon polyphosphate cyanurate (melonpolyphosphate) and the like. Other nitrogen-containing synergists that may be used include benzoguanamine, tris (hydroxyethyl) isocyanurate, allantoin, glycoluril, guanidine or a mixture thereof. Typically, only a small amount of nitrogen-containing synergist is required in the polymer composition. For example, the nitrogen-containing synergist can be present in the polymer composition in an amount less than about 4 wt%, such as in an amount less than about 3.4 wt%, such as in an amount less than about 2.3 wt%, such as in an amount less than about 1.8 wt%, such as in an amount less than about 1.5 wt%, and typically in an amount greater than about 0.1 wt%, such as in an amount greater than about 0.3 wt%, such as in an amount greater than about 0.8 wt%, such as in an amount greater than about 1.1 wt%.

[0032] In addition to the thermoplastic polymer and flame retardant composition described above, the polymer composition of the present disclosure may further comprise polytetrafluoroethylene and / or an organometallic compatibilizer.

[0033] For example, the flame retardant polymer composition of the present disclosure may contain fluoropolymers, such as polytetrafluoroethylene powder. For example, the polytetrafluoroethylene particles may have an average particle size of less than about 15 microns, such as less than about 12 microns, such as less than about 10 microns, such as less than about 8 microns. The average particle size of the polytetrafluoroethylene particles is generally greater than about 0.5 microns, such as greater than about 1 micron, such as greater than about 2 microns, such as greater than about 3 microns, such as greater than about 4 microns, such as greater than about 5 microns. The average particle size can be measured according to ISO test 13321.

[0034] In one embodiment, the polytetrafluoroethylene particles can have a relatively low molecular weight. When tested according to ASTM test D4895, the polytetrafluoroethylene polymer can have a density of about 300 g / l to about 450 g / l, such as about 325 g / l to about 375 g / l. When tested according to test DIN 66132, the polytetrafluoroethylene particles can have a density of about 5 m 2 / g to about 15m 2 / g, for example, about 8m 2 / g to about 12m 2 When tested according to ISO test 1133 at 372° C. and 10 kg load, the melt flow rate of the polytetrafluoroethylene polymer may be less than about 3 g / 10 min, such as less than about 2 g / 10 min.

[0035] The polytetrafluoroethylene particles may be present in the polymer composition in an amount greater than about 0.1 wt%, such as greater than about 0.2 wt%, such as greater than about 0.3 wt%, such as greater than about 0.4 wt%. The polytetrafluoroethylene particles are typically present in the polymer composition in an amount less than about 5 wt%, such as less than about 4 wt%, such as less than about 3 wt%, such as less than about 2 wt%.

[0036] When present in a polymer composition, the fluoropolymers described above can provide a variety of benefits and advantages. For example, the fluoropolymers can improve various physical properties of molded articles made from the polymer composition. In addition, the fluoropolymers can facilitate melt processing of the polymer composition. The fluoropolymers can also have flame retardant properties. For example, when exposed to an open flame, the fluoropolymers can maintain the polymer composition as a cohesive mass and can inhibit the molten polymer material from separating from the polymer composition to form droplets during a flame test.

[0037] The polymer composition may also include an organometallic compatibilizer. It has been found that organometallic compatibilizers surprisingly significantly improve the flow properties of the polymer composition during processing. In addition, organometallic compatibilizers can provide various other benefits and advantages. For example, organometallic compatibilizers can provide corrosion resistance, increase the acid resistance of the polymer composition, and improve the long-term aging performance of the polymer composition. In addition, organometallic compatibilizers can be used as intumescent flame retardants in certain applications.

[0038] The organometallic compatibilizer may comprise a monoalkoxy titanate.Other organometallic compounds that may be used include zirconates and aluminates. Specific examples of titanates that can be incorporated into the polymer composition include: 2-propoxy triisooctadecanoato-O; bis 2-methyl-2-propenoato-O,isooctadecanoato-O 2-propanolato; tris(dodecyl)benzenesulfanato-O; tris(dioctyl)phosphato-O; and tris(2-methyl)-2-propenoate-O-methoxydiglycolate. IV,tris(2-methyl)-2-propenoato-O,methoxydiglycolylato); 2-propoxytri(dodecyl)pyrophosphate-O titanium(IV) (Titanium IV2-propanolato,tris(dioctyl)pyrophosphato-O); tris(2-propoxy-O)methoxydiglycolate titanium(IV) (Titanium IV,tris(2-propenoato-O),methoxydiglycolylato-O); 2-propoxytris(3,6-diaza)hexanolato titanium(IV) (Titanium IV 2-propanolato,tris(3,6-diaza)hexanolato), and mixtures thereof.

[0039] When present in the polymer composition, the content of the organometallic compatibilizer can generally be greater than about 0.05wt%, such as greater than about 0.1wt%, such as greater than about 0.2wt%, such as greater than about 0.4wt%, and generally less than about 2.8wt%, such as less than about 2.5wt%, such as less than about 2.2wt%, such as less than about 1.8wt%, such as less than about 1.6wt%, such as less than about 1.2wt%.

[0040] Thermoplastic polymer compositions of the present invention can also include lubricants accounting for about 0.01wt% to about 2wt% of the polymer composition, about 0.1wt% to about 1wt% in some embodiments, and about 0.2wt% to about 0.5wt% in some embodiments. Lubricants can be formed by fatty acid salts derived from fatty acids having a chain length of 22 to 38 carbon atoms, 24 to 36 carbon atoms in some embodiments. Examples of such fatty acids can include long-chain aliphatic fatty acids, such as montanic acid (octacosanoic acid), arachidic acid (arachidic acid, eicosanoic acid, eicosanoic acid, n-eicosanoic acid), lignoceric acid (lignoceric acid), behenic acid (behenic acid), hexacosanoic acid (ceric acid), melissic acid (triacontanoic acid), erucic acid, cetylene acid, basilic acid, shark acid, nervonic acid, etc. For example, montanic acid has an aliphatic carbon chain of 28 atoms, and arachidic acid has an aliphatic carbon chain of 20 atoms. Due to the long carbon chain provided by fatty acids, lubricants have high thermal stability and low volatility. This allows the lubricant to maintain its function during the formation of the desired article to reduce internal and external friction, thereby reducing material degradation caused by mechanical / chemical effects.

[0041] Fatty acid salts can be formed by saponification of fatty acid waxes to neutralize excess carboxylic acid and form metal salts. Saponification can occur with metal hydroxides, such as alkali metal hydroxides (e.g., sodium hydroxide) or alkaline earth metal hydroxides (e.g., calcium hydroxide). The resulting fatty acid salts typically include alkali metals (e.g., sodium, potassium, lithium, etc.) or alkaline earth metals (e.g., calcium, magnesium, etc.). The acid value (ASTM D 1386) of such fatty acid salts is typically about 20 mg KOH / g or less, in some embodiments about 18 mg KOH / g or less, and in some embodiments, about 1 mg KOH / g to about 15 mg KOH / g. Particularly suitable fatty acid salts for use in the present invention are derived from crude montan wax, which contains chain lengths in the range of C 28 -C 32 Straight-chain, unbranched monocarboxylic acids in the range of 1,2-dimethoxy- ... CaV 102 (calcium salt of long-chain linear montanic acid) and NaV 101 (sodium salt of long chain linear montanic acid) was commercially available.

[0042] If necessary, fatty acid esters can be used as lubricants. Fatty acid esters can be obtained by oxidative bleaching of crude natural wax and then esterifying fatty acids with alcohols. The alcohol usually has 1 to 4 hydroxyls and 2 to 20 carbon atoms. When the alcohol is multifunctional (for example, 2 to 4 hydroxyl groups), 2 to 8 carbon atoms are particularly required. Particularly suitable multifunctional alcohols can include diols (for example, ethylene glycol, propylene glycol, butylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol and 1,4-cyclohexanediol), triols (for example, glycerol and trimethylolpropane), tetraols (for example pentaerythritol and erythritol) etc. Aromatic alcohols may also be suitable, for example o-, m- and p-toluene alcohol, chlorobenzyl alcohol, bromobenzyl alcohol, 2,4-dimethylbenzyl alcohol, 3,5-dimethylbenzyl alcohol, 2,3,5-isopropylbenzyl alcohol, 3,4,5-trimethylbenzyl alcohol, p-cumyl alcohol, 1,2-o-phthalic alcohol, 1,3-bis(hydroxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, pseudoisopropylbenzene glycol, mesitylene glycol and mesitylene glycerol. Particularly suitable fatty acid esters for use in the present invention are derived from montan wax. For example, OP (Clariant) contains montanic acid partially esterified with butanediol and montanic acid partially saponified with calcium hydroxide. OP contains a mixture of montanic acid esters and calcium montanic acid. Other montanic acid esters that can be used include E. OP and WE 4 (both from Clariant), for example, are montanic acid esters which are obtained as by-products from the oxidative refining of crude montan wax. E and WE 4 contains montanic acid esterified with ethylene glycol or glycerol.

[0043] Other known waxes can also be used in lubricants. For example, amide waxes formed by reacting fatty acids with monoamines or diamines (e.g., ethylenediamine) having 2 to 18, especially 2 to 8, carbon atoms can be used. For example, ethylenebisamide waxes formed by amidation of ethylenediamine and fatty acids can be used. The fatty acids can be in the C 12 To C 30 In the range of, for example, stearic acid (C 18 Fatty acids) form ethylene bis stearamide wax. Ethylene bis stearamide wax is available from Lonza, Inc. under the name C, which has a discrete melting temperature of 142°C. Other ethylenebisamides include bisamides formed from lauric acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, oleostearic acid, myristic acid, and undecanoic acid. Still other suitable amide waxes are N-(2-hydroxyethyl) 12-hydroxystearamide and N,N'-(ethylenebis) 12-hydroxystearamide, which are available from CasChem, a division of Rutherford Chemicals LLC, under the names 220 and 285 was purchased commercially.

[0044] The polymer composition may further include at least one stabilizer. The stabilizer may include an antioxidant, a light stabilizer such as an ultraviolet light stabilizer, a heat stabilizer, and the like.

[0045] Sterically hindered phenolic antioxidants may be used in the composition. Examples of such phenolic antioxidants include, for example, calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate) ( 1425); 1,4-dithio-, S,S-bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) terephthalate ( 1729); triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylhydrocinnamate); hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) ( 259); 1,2-bis(3,5,di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide( 1024); 4,4'-di-tert-octyl diphenylamine ( 438R); Phosphonic acid (3,5-di-tert-butyl-4-hydroxybenzyl)-dioctadecyl ester ( 1093); 1,3,5-trimethyl-2,4,6-tri(3',5'-di-tert-butyl-4'-hydroxybenzyl)benzene( 1330); 2,4-bis(octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine ( 565); 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate ( 1135); 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate ( 1076); 3,7-bis(1,1,3,3-tetramethylbutyl)-10H-phenothiazine ( LO 3); 2,2'-methylenebis(4-methyl-6-tert-butylphenol) monoacrylate ( 3052); 2-tert-butyl-6-[1-(3-tert-butyl-2-hydroxy-5-methylphenyl)ethyl]-4-methylphenyl acrylate ( TM 4039); 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate ( GS); 1,3-dihydro-2H-benzimidazole ( MB); 2-methyl-4,6-bis[(octylthio)methyl]phenol ( 1520); N,N'-trimethylenebis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide ( 1019); 4-n-octadecyloxy-2,6-diphenylphenol ( 1063); 2,2'-ethylenebis[4,6-di-tert-butylphenol]( 129); N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid) ( 1098); (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonic acid diethyl ester ( 1222); 4,4'-di-tert-octyl diphenylamine ( 5057); N-phenyl-1-naphthylamine ( L 05); tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-6-methylphenylthio)-5-methylphenyl]phosphite ( OSP 1); Zinc dinonyl dithiocarbamate ( VP-ZNCS 1); 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane ( AG80); Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]( 1010); Ethylene-bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate ( 245); 3,5-di-tert-butyl-4-hydroxytoluene (Lowinox BHT, Chemtura), etc.

[0046] Some examples of suitable sterically hindered phenolic antioxidants for use in the present composition are triazine antioxidants having the following general formula:

[0047]

[0048] Wherein, each R is independently a phenolic group, which may be connected to the triazine ring via a C1 to C5 alkyl or ester substituent. Preferably, each R is one of the following formulas (I)-(III):

[0049]

[0050] Commercial examples of such triazine-based antioxidants are available from American Cyanamid under the name 1790 (wherein each R group is represented by Formula III) and from Ciba Specialty Chemicals under the name 3114 (wherein each R group is represented by formula I) and 3125 (wherein each R group is represented by formula II) is obtained.

[0051] The sterically hindered phenolic antioxidant may comprise from about 0.01 wt.% to about 3 wt.%, in some embodiments from about 0.05 wt.% to about 1 wt.%, and in some embodiments from about 0.05 wt.% to about 0.3 wt.% of the total stabilized polymer composition. For example, in one embodiment, the antioxidant comprises pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0052] Hindered amine light stabilizer (HALS) can be used in the composition to inhibit degradation of the polyester composition and thus extend its durability. Suitable HALS compounds can be derived from substituted piperidines, such as alkyl-substituted piperidinyl, piperidinyl, piperazinone, alkoxypiperidinyl compounds, etc. For example, the hindered amine can be derived from 2,2,6,6-tetraalkylpiperidinyl. Regardless of the compound from which it is derived, the hindered amine is generally an oligomeric or polymeric compound having a number average molecular weight of about 1000 or more, in some embodiments, from about 1000 to about 20000, in some embodiments, from about 1500 to about 15000, and in some embodiments, from about 2000 to about 5000. Each polymer repeating unit of such a compound generally contains at least one (e.g., 1 to 4) 2,2,6,6-tetraalkylpiperidinyl.

[0053] Without being limited by theory, it is believed that high molecular weight hindered amines are relatively thermally stable and thus are able to resist photodegradation even after being subjected to extrusion conditions. A particularly suitable high molecular weight hindered amine has the following general structure:

[0054]

[0055] wherein p is from 4 to 30, in some embodiments from 4 to 20, and in some embodiments from 4 to 10. Such oligomeric compounds are available from Clariant under the name N30 is commercially available and has a number average molecular weight of 1,200.

[0056] Another suitable high molecular weight hindered amine has the following structure:

[0057]

[0058] Where n is 1 to 4 and R 30 independently hydrogen or CH3. Such oligomeric compounds are available from Adeka Palmarole SAS (a joint venture between Adeka Corp. and Palmarole Group) under the name ADK LA-63(R 30 is CH3) and ADK LA-68(R 30 is hydrogen) is commercially available.

[0059] Other examples of suitable high molecular weight hindered amines include, for example, oligomers of N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol and succinic acid (available from Ciba Specialty Chemicals). 622, MW = 4000); oligomers of cyanuric acid and N, N-bis (2,2,6,6-tetramethyl-4-piperidinyl) -hexamethylenediamine; poly ((6-morpholine-S-triazine-2,4-diyl) (2,2,6,6-tetramethyl-4-piperidinyl) -iminohexamethylene- (2,2,6,6-tetramethyl-4-piperidinyl) -imino) (from Cytec UV 3346, MW = 1600); polymethylpropyl-3-oxy-[4 (2,2,6,6-tetramethyl)-piperidinylsiloxane (from Great Lakes Chemical 299, MW = 1100 to 2500); copolymer of α-methylstyrene-N-(2,2,6,6-tetramethyl-4-piperidinyl)maleimide and N-stearylmaleimide; 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol tetramethyl-polymer and 1,2,3,4-butanetetracarboxylic acid; and the like.

[0060] In addition to high molecular weight hindered amines, low molecular weight hindered amines can also be used in the composition. Such hindered amines are generally monomeric and have a molecular weight of about 1000 or less, in some embodiments from about 155 to about 800, and in some embodiments from about 300 to about 800.

[0061] Specific examples of such low molecular weight hindered amines may include, for example, bis-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (available from Ciba Specialty Chemicals 770, Mw = 481); bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)-(3,5-di-tert-butyl-4-hydroxybenzyl)butyl-propane dioate; bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro-(4,5)-decane- 2,4-diketosuccinic acid-bis-(2,2,6,6-tetramethyl-4-piperidinyl) ester; tetrakis-(2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butane tetracarboxylate; 7-oxa-3,20-diazadispiro(5.1.11.2)heneicosane-20-propionic acid 2,2,4,4-tetramethyl-21-oxododecyl ester; N-(2,2 ,6,6-tetramethyl-4-piperidinyl)-N'-aminooxamide; ot-pentyl-o-(1,2,2,6,6-pentamethyl-4-piperidinyl) peroxycarbonate; β-alanine N-(2,2,6,6-tetramethyl-4-piperidinyl) dodecyl ester; N-(1-acetyl-2,2,6,6-tetramethylpiperidinyl)-N'-dodecylethaneamide; 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidine-2,5-dione; 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidinyl)-pyrrolidine-2,5-dione; 3-dodecyl-1-(1-acetyl,2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidine-2,5-dione (from Clariant 3058, MW = 448.7); 4-benzoyloxy-2,2,6,6-tetramethylpiperidine; 1-[2-(3,5-di-tert-butyl-4-hydroxyphenylpropionyloxy)ethyl]-4-(3,5-di-tert-butyl-4-hydroxyphenylpropionyloxy)-2,2,6,6-tetramethylpiperidine; 2-methyl-2-(2",2",6",6"-tetramethyl-4"-piperidinylamino)-N-(2',2',6',6'-tetramethyl-4'-piperidinyl)propionamide; 1,2-bis-(3,3,5,5-tetramethyl-2-oxo-piperazinyl)ethane; 4-oleoyloxy-2,2,6,6-tetramethylpiperidine; and combinations thereof. Other suitable low molecular weight hindered amines are described in U.S. Pat. No. 5,679,733 to Malik et al.

[0062] The hindered amines may be used alone or in combination in any amount to achieve the desired properties, but generally comprise from about 0.01 wt % to about 4 wt % of the polymer composition.

[0063] UV absorbers, such as benzotriazoles or benzophenones, may be used in the composition to absorb ultraviolet light energy. Suitable benzotriazoles may include, for example, 2-(2-hydroxyphenyl)benzotriazoles, such as 2-(2-hydroxy-5-methylphenyl)benzotriazole; 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole (from Cytec); UV 5411); 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole; 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole; 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole; 2,2'-methylenebis(4-tert-octyl-6-benzotriazolylphenol); polyethylene glycol ester of 2-(2-hydroxy-3-tert-butyl-5-carboxyphenyl)benzotriazole; 2-[2-hydroxy-3-(2-acryloyloxyethyl)-5-methylphenyl]benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-butylphenyl]benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-octylphenyl]benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-octylphenyl]benzotriazole; 2-[2-hydroxy-3-tert-butyl-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-butyl-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-amyl-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-butyl-5-(3-methacryloyloxypropyl)phenyl]-5-chlorobenzotriazole; 2-[2-hydroxy-4-(2-methacryloyloxymethyl)phenyl]benzotriazole; 2-[2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropyl)phenyl]benzotriazole; 2-[2-hydroxy-4-(3-methacryloyloxypropyl)phenyl]benzotriazole; and combinations thereof.

[0064] Exemplary benzophenone light stabilizers may also include: 2-hydroxy-4-dodecyloxybenzophenone; 2,4-dihydroxybenzophenone; 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate (available from Cytec UV209); 2-hydroxy-4-n-octyloxy)benzophenone (from Cytec 531); 2,2'-dihydroxy-4-(octyloxy)benzophenone (from Cytec UV 314); hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate (from Cytec UV 2908); 2,2'-thiobis(4-tert-octylphenol)-n-butylamine nickel(II) (from Cytec UV 1084); 3,5-di-tert-butyl-4-hydroxybenzoate (2,4-di-tert-butylphenyl) (from Cytec 712); 4,4'-dimethoxy-2,2'-dihydroxybenzophenone (from Cytec UV 12); and combinations thereof.

[0065] When used, UV absorbers may comprise from about 0.01 wt % to about 4 wt % of the total polymer composition.

[0066] In one embodiment, the polymer composition may include a mixture of stabilizers that produce UV resistance and color stability. The combination of stabilizers can allow for the production of products with bright and fluorescent colors. In addition, products can be produced that are brightly colored and do not fade significantly over time. For example, in one embodiment, the polymer composition may include a combination of a benzotriazole light stabilizer and a hindered amine light stabilizer such as an oligomeric hindered amine.

[0067] Organophosphorus compounds can be used as secondary antioxidants in the composition to decompose peroxides and hydroperoxides into stable non-radical products. Trivalent organophosphorus compounds (e.g., phosphites or phosphonites) are particularly useful in the stabilization system of the present invention. In certain embodiments of the present invention, monophosphite compounds (i.e., only one phosphorus atom per molecule) can be used. Preferred monophosphites are those containing C1 to C2 on at least one aryloxy group. 10 Aryl monophosphites with alkyl substituents. These substituents may be straight chain (such as in the case of nonyl substituents) or branched (such as isopropyl or tert-butyl substituents). Non-limiting examples of suitable aryl monophosphites (or monophosphonites) may include: triphenyl phosphite; diphenyl alkyl phosphites; phenyl dialkyl phosphites; tris(nonylphenyl)phosphite (Weston TM 399, purchased from GE Specialty Chemicals); tris(2,4-di-tert-butylphenyl)phosphite ( 168, available from Ciba Specialty Chemicals Corp.); ethyl bis(2,4-di-tert-butyl-6-methylphenyl)phosphite ( 38, purchased from Ciba Specialty Chemicals Corp.); and 2,2',2"-nitrogen [triethyl tris (3,3'5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) phosphate ( 12, available from Ciba Specialty Chemicals Corp.). Aryl diphosphites or diphosphonites (i.e., containing at least two phosphorus atoms per phosphite molecule) may also be used in the stabilizing system and may include, for example, distearyl pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (available from Ciba as Irgafos 126); di(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite; diisodecyloxypentaerythritol diphosphite; di(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite; bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite; tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene-diphosphonite (available from Clariant as Sandostab TM P-EPQ) and bis(2,4-dicumylphenyl)pentaerythritol diphosphite ( S-9228).

[0068] The organophosphorus compound may comprise from about 0.01 wt % to about 2 wt %, in some embodiments from about 0.05 wt % to about 1 wt %, and in some embodiments from about 0.1 wt % to about 0.5 wt % of the polymer composition.

[0069] In addition to those mentioned above, secondary amines may also be used in the composition. The secondary amines may be aromatic in nature, such as N-phenylnaphthylamine (e.g., N-phenylnaphthylamine from Uniroyal Chemical). PAN); diphenylamines, such as 4,4'-bis(dimethylbenzyl)-diphenylamine (e.g., 445); p-phenylenediamine (e.g. from Goodyear 300); quinolones, etc. Particularly suitable secondary amines are oligoamines or polymeric amines, such as homopolymeric or copolymeric polyamides. Examples of such polyamides may include nylon 3 (poly-β-alanine), nylon 6, nylon 10, nylon 11, nylon 12, nylon 6 / 6, nylon 6 / 9, nylon 6 / 10, nylon 6 / 11, nylon 6 / 12, polyesteramide, polyamideimide, polyacrylamide, etc. In a specific embodiment, the amine is a polyamide terpolymer having a melting point in the range of 120° C. to 220° C. Suitable terpolymers may be based on nylons selected from nylon 6, nylon 6 / 6, nylon 6 / 9, nylon 6 / 10, and nylon 6 / 12, and may include nylon 6-66-69; nylon 6-66-610 and nylon 6-66-612. An example of such a nylon terpolymer is nylon 6-66-610 terpolymer and is available from Du Pont de Nemours under the name 8063R is commercially available.

[0070] The secondary amine may comprise from about 0.01 wt % to about 2 wt % of the entire polymer composition.

[0071] In addition to the above ingredients, the polymer composition may also include various other ingredients. Colorants that may be used include any desired inorganic pigments, such as titanium dioxide, ultramarine, cobalt blue, and other organic pigments and dyes, such as phthalocyanines, anthraquinones, etc. Other colorants include carbon black or various other polymer-soluble dyes. The colorant is typically present in the composition in an amount of up to about 2 wt%.

[0072] In addition to the thermoplastic polymer matrix, the polymer composition may also comprise reinforcing fibers. The reinforcing fibers that may advantageously be used are mineral fibers (e.g. glass fibers), polymer fibers (in particular organic high modulus fibers, e.g. aramid fibers), or metal fibers (e.g. steel fibers), or carbon fibers or natural fibers, fibers from renewable resources.

[0073] These fibers may be in modified or unmodified form, for example provided with a size or chemically treated in order to improve adhesion to plastics. Glass fibers are particularly preferred.

[0074] Glass fibers have a size to protect the glass fibers, smooth the fibers, but also improve the adhesion between the fibers and the matrix material. The size typically contains silanes, film formers, lubricants, wetting agents, binders, optional antistatic agents and plasticizers, emulsifiers and optional other additives.

[0075] Specific examples of silanes are aminosilanes, such as 3-trimethoxysilylpropylamine, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(3-trimethoxysilylpropyl)ethane-1,2-diamine, 3-(2-aminoethyl-amino)propyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]-1,2-ethane-diamine.

[0076] Film formers are, for example, polyvinyl acetates, polyesters and polyurethanes. Polyurethane-based sizing compounds can advantageously be used.

[0077] The reinforcing fibers can be mixed into the polymer matrix, for example, in an extruder or a kneader.

[0078] According to one embodiment, the molding composition of the present disclosure comprises at least one reinforcing fiber, which is a mineral fiber, preferably a glass fiber, more preferably a coated or impregnated glass fiber. Glass fibers suitable for the molding composition of the present disclosure are commercially available, for example, Johns Manville, Chopped Strand 753, OCV Chopped Strand 408 A, Nippon Electric Glass Co. (NEG) Chopped Strand T-651.

[0079] The fiber diameter can vary according to the specific fiber used and whether the fiber is in chopped form or continuous form. For example, the fiber can have a diameter of about 5 μm to about 100 μm, such as about 5 μm to about 50 μm, such as about 5 μm to about 15 μm. The length of the fiber can vary according to specific applications. For example, the fiber can have a length greater than about 100 microns, such as greater than about 200 microns, such as greater than about 300 microns, such as greater than about 350 microns. The length of the fiber can be generally less than about 1000 microns, such as less than about 800 microns, such as less than about 600 microns, such as less than about 500 microns. Once incorporated into the polymer composition and molded into articles, the fiber length will be reduced. For example, the average fiber length in the final product can be about 100 microns to about 400 microns, such as about 100 microns to about 300 microns.

[0080] Typically, reinforcing fibers are optionally present in the polymer composition in an amount sufficient to increase the tensile strength of the composition. For example, reinforcing fibers can be present in the polymer composition in an amount greater than about 2%, for example, in an amount greater than about 5%, for example, in an amount greater than about 10%, for example, in an amount greater than about 15%, for example, in an amount greater than about 20%. Reinforcing fibers are typically present in an amount less than about 55wt%, for example, in an amount less than about 50wt%, for example, in an amount less than about 45wt%, for example, in an amount less than about 40wt%, for example, in an amount less than about 35wt%, for example, in an amount less than about 30wt%.

[0081] The compositions of the present disclosure can be compounded and formed into polymer articles using any technique known in the art. For example, the respective compositions can be mixed vigorously to form a substantially uniform blend. The blend can be melt-kneaded at an elevated temperature, the elevated temperature being, for example, higher than the melting point of the polymer used in the polymer composition but lower than the temperature of the degradation temperature. Alternatively, the respective compositions can be melted and mixed together in a conventional single screw or twin screw extruder. Preferably, melt mixing is carried out at a temperature of 150°C to 300°C, for example, 200°C to 280°C, for example, 220°C to 270°C or 240°C to 260°C. However, this processing should be carried out at a desired temperature to each composition to minimize any polymer degradation.

[0082] After extrusion, the composition can be made into pellets. The pellets can be formed into polymer articles by techniques known in the art, such as injection molding, thermoforming, blow molding, rotational molding, etc. According to the present disclosure, the polymer articles show excellent tribological behavior and mechanical properties. Therefore, the polymer articles can be used for a variety of applications requiring low wear and excellent sliding properties.

[0083] The polymer composition according to the present disclosure may also have excellent flame retardant properties in addition to physical properties. For example, when tested according to the vertical burning test in accordance with the Underwriters Laboratories Test 94, a test panel made according to the present disclosure may have a UL-94 rating of V-0 even at a thickness of 0.8 mm or even at a thickness of 0.4 mm.

[0084] Particularly advantageously, flame retardant polymer compositions having excellent flow properties can be formulated according to the present disclosure. For example, when tested according to ISO test 1133 at a temperature of 250° C. and a load of 2.16 kg, the melt flow rate of the entire polymer composition can be greater than about 3 cm 3 / 10min, for example, greater than about 4cm 3 / 10min, for example, greater than about 5cm 3 / 10min, for example, greater than about 6cm 3 / 10min, for example, greater than about 7cm 3 / 10min, for example, greater than about 8cm 3 / 10min, for example, greater than about 9cm 3 / 10min, for example, greater than about 10cm 3 / 10min. The melt flow rate is usually less than about 50cm 3 / 10min.

[0085] The polymer compositions of the present disclosure may also have excellent mechanical properties when tested according to ISO Test No. 527. For example, the polymer compositions may have a mechanical strength of greater than about 3400 N / mm 2 And usually less than about 5000N / mm 2 The tensile modulus at yield can generally be greater than about 40 N / mm 2 , for example greater than about 43N / mm 2 , and is usually less than about 70N / mm 2 The tensile strength at break can be greater than about 40 N / mm 2 , for example greater than about 43N / mm 2 , and is usually less than about 70N / mm 2 The elongation at break may be greater than about 4%, such as greater than about 5%, and typically less than about 25%.

[0086] The present disclosure may be better understood with reference to the following examples.

[0087] Example

[0088] Various polymer compositions were formulated according to the present disclosure and tested for various properties. The following results were obtained.

[0089] Table 1

[0090]

[0091]

[0092] The titanate coupling agent used in Samples 4 and 5 was 2-propoxytri(dioctyl)phosphate O-titanium(IV).

[0093] As shown above, samples No. 3 to No. 5 have a V-0 rating even at a thickness of 0.4 mm. In addition, the samples containing the titanate coupling agent exhibit significantly better melt flow properties.

[0094] Without departing from the spirit and scope of the present invention as more specifically set forth in the appended claims, those of ordinary skill in the art may make these and other improvements and modifications to the present invention. In addition, it should be understood that the aspects of the various embodiments may be fully interchangeable or partially interchangeable. In addition, those of ordinary skill in the art will appreciate that the foregoing description is exemplary only and is not intended to limit the present invention as further described in the appended claims.

Claims

1. A flame retardant polymer composition comprising: a thermoplastic polyester polymer, said thermoplastic polyester polymer being present in said polymer composition in an amount greater than 60 wt %; a flame retardant composition contained in the polymer composition, the flame retardant composition comprising a combination of a metal phosphinate, a metal phosphite, and a nitrogen-containing synergist; an organometallic compatibilizer, the organometallic compatibilizer comprising a titanate; and Polytetrafluoroethylene; wherein the polymer composition is free of glass fibers and exhibits an elongation at break greater than 4% when tested according to ISO Test No. 527; The titanate comprises 2-propoxytri(dioctyl)phosphate O-titanium(IV).

2. The flame retardant polymer composition according to claim 1, wherein The metal phosphite includes aluminum phosphite.

3. The flame retardant polymer composition according to claim 2, wherein The aluminum phosphite has the following chemical formula: Al2(HPO3)3.

4. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The metal phosphinates include dialkyl phosphinates.

5. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The metal phosphinate includes aluminum diethylphosphinate.

6. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The nitrogen-containing synergist includes melamine cyanurate.

7. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The metal phosphinate is present in the composition in an amount of 10 wt % to 25 wt %, the metal phosphite is present in the polymer composition in an amount of 1 wt % to 7 wt %, and the nitrogen-containing synergist is present in the polymer composition in an amount of 0.3 wt % to 4 wt %.

8. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The polytetrafluoroethylene is present in the polymer composition in an amount of 0.1 wt % to 5 wt %.

9. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The thermoplastic polyester polymer includes a polybutylene terephthalate polymer.

10. The flame retardant polymer composition according to claim 1, wherein The organometallic compatibilizer is present in the polymer composition in an amount of 0.05 wt % to 2.5 wt %.

11. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The polymer composition also includes an ester of a carboxylic acid.

12. The flame retardant polymer composition according to claim 11, wherein The esters of the carboxylic acids include reaction products of montanic acid and polyfunctional alcohols.

13. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The polymer composition is free of metal oxides, metal hydroxides, metal borates and metal stannates.

14. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The polymer composition has a thickness of at least 6.0 cm when tested at a temperature of 250°C and a load of 2.16 kg. 3 / 10min melt flow rate.

15. The flame retardant polymer composition according to any one of claims 1 to 3, wherein When tested according to the Underwriters Laboratories Test 94 Vertical Burning Test, the polymer composition was rated V-0 when tested at a thickness of 0.4 mm.

16. The flame retardant polymer composition according to any one of claims 1 to 3, wherein The metal phosphinate is present in the composition in an amount of 5 wt % to 30 wt %, the metal phosphite is present in the polymer composition in an amount of 0.5 wt % to 9 wt %, and the nitrogen-containing synergist is present in the polymer composition in an amount of 0.01 wt % to 7 wt %.

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