WO2014036871A1

WO2014036871A1 - Fire-retardant copolyetherester composition and articles comprising the same

Info

Publication number: WO2014036871A1
Application number: PCT/CN2013/080626
Authority: WO
Inventors: Eleni Karayianni; Ting Li; Yong Ni
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2012-09-06
Filing date: 2013-08-01
Publication date: 2014-03-13
Also published as: DE112013004371T5; CN103665779A; DE112013004371B4; CN103665779B

Abstract

Disclosed herein is a fire-retardant copolyetherester composition comprising: (a) about 20-93.9 wt% of at least one copolyetherester; (b) about 5- 30 wt% of at least one halogen-free flame retardant; (c) about 0.1-20 wt% of at least one nitrogen-containing compound; and (d) about 1-30 wt% of at least one composite rubber-based graft copolymer. Further disclosed herein are articles comprising component parts formed of the fire-retardant copolyetherester composition.

Description

FIRE-RETARDANT COPOLYETHERESTER COMPOSITION

AND ARTICLES COMPRISING THE SAME

TECHNICAL FIELD

The disclosure is related to fire-retardant copolyetherester compositions with good thermal stability and articles comprising the same.

BACKGROUND

Due to its excellent mechanical properties (e.g., tear strength, tensile strength, flex life, and abrasion resistance), polymeric compositions based on copolyetherester elastomers have been used in forming components for motorized vehicles and electrical/electronic devices. However, often times, electric arc may be formed and high temperature may be reached within the under-hood areas of vehicles and inside electrical/electronic devices. Thus, while maintaining other mechanical properties, it is desirable that such copolyetherester based compositions also have low flammability and high thermal stability.

Various flame retardant systems have been developed and used in polymeric material, e.g., polyesters, to improve the fire-resistance thereof.

However, due to toxicity concerns, halogen-free flame retardants are gaining more and more attention. Among the various halogen-free flame retardants, phosphorus compounds (such as salts of phosphinic or diphosphinic acids) are used the most due to the stability and flame-retardant effectiveness thereof. Prior art has also demonstrated that various types of synergistic compounds can be used as synergists in combination with the phosphorus compounds to further maximize the flame-retardant effectiveness thereof. For example, U.S. Patent No. 6,547,992 discloses the use of synthetic inorganic compounds such as oxygen compounds of silicon, magnesium compounds, metal carbonates of metals of the second main group of the periodic table, red phosphorus, zinc compounds, aluminum compounds, or combinations thereof as flame retardant synergists; U.S. Patent No. 6,716,899 discloses the use of organic phosphorus- containing compounds as flame retardant synergists; U.S. Patent No. 6,365,071 discloses the use of nitrogen-containing compounds (e.g., melamine cyanurate, melamine phosphate, melamine pyrophosphate, or melamine diborate) as flame retardant synergists; and U.S. Patent No. 6,255,371 discloses the use of reaction products of phosphoric acids with melamine or condensed product of melamine (e.g., melamine polyphosphate (MPP)) as flame retardant synergists.

Composite rubber-based graft copolymers have been known and used as impact modifiers in polymeric material (such as polycarbonates or polyesters), see, e.g., U.S. Patent Nos. 4,888,388; 5,807,914; 6,423,766; 8,178,603, U.S. Patent Application Publication No. 2012/0074617, and EP Patent No. 0430134. The use of such composite rubber-based graft copolymers in thermoplastic polyester elastomers have also been disclosed in, e.g., PCT Publication No.

WO03/042299, U.S. Patent Application No. 2003/0008141 , JP Patent Publication Nos. 07-157643 and 2005281465. Moreover, U.S. Patent Application Publication No. 201 1/0275743 discloses a halogen-free fire-retardant polyester composition, in which various vinyl resins were suggested to be added to improve the impact strength thereof.

However, there has been no disclosure in the prior art such composite rubber-based graft copolymers, in combination with a specific halogen-free flame retardant package, can improve the thermal stability and chemical resistance for copolyetherester materials.

SUMMARY

The purpose of the present disclosure is to provide a fire-retardant copolyetherester composition having improved thermal stability, which comprises: (a) 20-93.9 wt% of at least one copolyetherester; (b) 5-30 wt% of at least one halogen-free flame retardant; (c) 0.1 -20 wt% of at least one nitrogen-containing compound; and (d) 1 -30 wt% of at least one composite rubber-based graft copolymer comprising at least one vinyl monomer grafted onto a silicone/acrylate composite rubber base, with the total weight of all components comprised in the composition totaling to 100 wt%, and wherein, the at least one halogen-free flame retardant comprises at least one selected from the group consisting of phosphinates of the formula (III), disphosphinates of the formula (IV), and combinations or polymers thereof

with R¹ and R² being identical or different and each of R¹ and R² being hydrogen, a linear, branched, or cyclic Ci -C₆ alkyl group, or a C₆-Ci₀ aryl; R³ being a linear or branched C1-C10 alkylene group, a C₆-Ci₀ arylene group, a C₆- C₁₂ alkyl-arylene group, or a C₆-Ci₂ aryl-alkylene group; M being selected from calcium ions, aluminum ions, magnesium ions, zinc ions, antimony ions, tin ions, germanium ions, titanium ions, iron ions, zirconium ions, cerium ions, bismuth ions, strontium ions, manganese ions, lithium ions, sodium ions, potassium ions and combinations thereof; and m, n, and x each being a same or different integer of 1-4.

In one embodiment of the fire-retardant copolyetherester composition, the at least one halogen-free flame retardant is selected from the group consisting of aluminum methylethylphosphinate, aluminum diethylphosphinate, aluminum hypophosphite, and combinations or two or more thereof, or the at least one halogen-free flame retardant is aluminum methylethylphosphinate or aluminum diethylphosphinate.

In a further embodiment of the fire-retardant copolyetherester composition, the at least one halogen-free flame retardant has a median particle size D₅₀ equal to or greater than 5 μηη, or equal to or greater than 10 μηη, or equal to or greater than 15 μηη. In a yet further embodiment of the fire-retardant copolyetherester composition, the nitrogen-containing compound is selected from the group consisting of (i) melamine cyanurate, (ii) condensation products of melamine, (iii) reaction products of phosphoric acid with melamine, and (iv) reaction products of phosphoric acid with condensation products of melamine, or the at least one nitrogen-containing compound is melamine cyanurate.

In a yet further embodiment of the fire-retardant copolyetherester composition, the at least one vinyl monomer comprised in the composite rubber- based graft copolymers is selected from the group consisting of styrene, a- methylstyrene, methyl methacrylate, n-butyl acrylate, acrylonitrile, and

combinations of two or more thereof, or the at least one vinyl monomer is methyl methacrylate.

In a yet further embodiment of the fire-retardant copolyetherester composition, composite rubber-based graft copolymers comprises 5-95 wt%, or 10-95 wt%, or 10-90 wt% of the at least one vinyl monomers that are grafted onto the silicone/acrylate composite rubber, based on the total weight of the composite rubber-based graft copolymers.

In a yet further embodiment of the fire-retardant copolyetherester composition, the silicone/acrylate rubber base comprised in the composite rubber-based graft copolymer comprises 1 -99 wt%, or 1 -95 wt%, or 5-95 wt% of a silicone rubber component, with the remaining being a polyalkyl (meth)acrylate rubber component.

In a yet further embodiment of the fire-retardant copolyetherester composition, the composition comprises 30-85 wt% of the at least one

copolyetherester; 7.5-25 wt% of the at least one halogen-free flame retardant; 1 - 15 wt% of the at least one nitrogen-containing compound; and 1 -20 wt% of the at least one composite rubber-based graft copolymer.

In a yet further embodiment of the fire-retardant copolyetherester composition, the composition comprises 40-70 wt% of the at least one

copolyetherester; 10-25 wt% of the at least one halogen-free flame retardant; 2- least one composite rubber-based graft copolymer.

Further provided herein is an article comprising at least one component part formed of the fire-retardant copolyetherester composition described hereabove. Preferably the article is selected from motorized vehicle parts and electrical/electronic devices. Or, the article is selected from insulated wires and cables, and preferably, the insulated wires and cables comprise one or more insulating layers and/or insulating jackets that are formed of the fire-retardant copolyetherester composition described hereabove.

Yet further provided herein is a fire-retardant copolyetherester composition having improved UV stability, which comprises: (a) at least one copolyetherester; (b) 5-30 wt% of at least one halogen-free flame retardant; (c) 0.1 -20 wt% of melamine cyanurate; (d) 0.1 -2 wt% of at least one organic UV absorber selected from the group consisting of benzotriazole based UV absorbers, benzophenone based UV absorber, and mixtures thereof; and (e) 0.1 -2 wt% of at least one hindered amine light stabilizer, with the total weight of all components comprised in the composition totaling to 100 wt%, and wherein, the at least one halogen- free flame retardant comprises at least one selected from the group consisting of phosphinates of the formula (III), disphosphinates of the formula (IV), and combinations or polymers thereof

with R¹ and R² being identical or different and each of R¹ and R² being hydrogen, a linear, branched, or cyclic Ci -C₆ alkyl group, or a C₆-Ci₀ aryl; R³ being a linear or branched C₁-C₁₀ alkylene group, a C₆-Ci₀ arylene group, a C₆- Ci₂ alkyl-arylene group, or a C₆-Ci₂ aryl-alkylene group; M being selected from calcium ions, aluminum ions, magnesium ions, zinc ions, antimony ions, tin ions, germanium ions, titanium ions, iron ions, zirconium ions, cerium ions, bismuth ions, strontium ions, manganese ions, lithium ions, sodium ions, potassium ions and combinations thereof; and m, n, and x each being a same or different integer of 1-4.

In accordance with the present disclosure, when a range is given with two particular end points, it is understood that the range includes any value that is within the two particular end points and any value that is equal to or about equal to any of the two end points.

DETAILED DESCRIPTION

Disclosed herein is a fire-retardant copolyetherester composition comprising,

(a) about 20-93.9 wt% of at least one copolyetherester;

(b) about 5-30 wt% of at least one halogen-free flame retardant;

(c) about 0.1 -20 wt% of at least one nitrogen-containing compound; and

(d) about 1 -30 wt% of at least one composite rubber-based graft copolymer comprising at least one vinyl monomer grafted onto a silicone/acrylate composite rubber base.

The copolyetheresters suitable for use in the compositions disclosed herein may be copolymers having a multiplicity of recurring long-chain ester units and recurring short-chain ester units joined head-to-tail through ester linkages, the long-chain ester units being represented by formula (I):

(!⁾

o o

II li

OOO— CRC

and the short-chain ester units being represented by formula (II)

wherein,

G is a divalent radical remaining after the removal of terminal hydroxyl groups from poly(alkylene oxide) glycols having a number average molecular weight of about 400-6000;

R is a divalent radical remaining after the removal of carboxyl groups from a dicarboxylic acid having a number average molecular weight of about 300 or less;

D is a divalent radical remaining after the removal of hydroxyl groups from a glycol having a number average molecular weight of about 250 or less, and wherein,

the at least one copolyetherester contains about 1 -85 wt% of the recurring long-chain ester units and about 15-99 wt% of the recurring short-chain ester units.

In one embodiment, the copolyetherester used in the composition disclosed herein contains about 5-80 wt% of the recurring long-chain ester units and about 20-95 wt% of the recurring short-chain ester units.

In a further embodiment, the copolyetherester used in the composition disclosed herein contains about 10-75 wt% of the recurring long-chain ester units and about 25-90 wt% of the recurring short-chain ester units.

In a yet further embodiment, the copolyetherester used in the composition disclosed herein contains about 40-75 wt% of the recurring long-chain ester units and about 25-60 wt% of the recurring short-chain ester units.

As used herein, the term "long-chain ester units" refers to reaction products of a long-chain glycol with a dicarboxylic acid. Suitable long-chain glycols are poly(alkylene oxide) glycols having terminal hydroxyl groups and a number average molecular weight of about 400-6000, or about 600-3000, which include, without limitation, poly(tetramethylene oxide) glycol, poly(trimethylene oxide) glycol, poly(propylene oxide) glycol, poly(ethylene oxide) glycol, copolymer glycols of these alkylene oxides, and block copolymers such as ethylene oxide-capped poly(propylene oxide) glycol. The long-chain glycols used herein may also be combinations of two or more of the above glycols. As used herein, the term "short-chain ester units" refers to reaction products of a low molecular weight glycol or an ester-forming derivative thereof with a dicarboxylic acid. Suitable low molecular weight glycols are those having a number average molecular weight of about 250 or lower, or about 10-250, or about 20-150, or about 50-100, which include, without limitation, aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, and aromatic dihydroxy compounds (including bisphenols). In one embodiment, the low molecular weight glycol used herein is a dihydroxy compound having 2-15 carbon atoms, such as ethylene glycol; propylene glycol; isobutylene glycol; 1 ,4-tetramethylene glycol; pentamethylene glycol; 2,2-dimethyltrimethylene glycol; hexamethylene glycol; decamethylene glycol; dihydroxycyclohexane; cyclohexanedimethanol; resorcinol; hydroquinone; 1 ,5-dihydroxynaphthalene; or the like. In a further embodiment, the low molecular weight glycol used herein is a dihydroxy compound having 2-8 carbon atoms. In a yet further embodiment, the low molecular weight glycol used herein is 1 ,4-tetramethylene glycol. Bisphenols that are useful herein include, without limitation, bis(p-hydroxy)diphenyl, bis(p- hydroxyphenyl)methane, bis(p-hydroxyphenyl)propane, and mixtures of two or more thereof.

The ester-forming derivatives of low molecular weight glycols useful herein include those derived from the low molecular weight glycols described above, such as ester-forming derivatives of ethylene glycol (e.g., ethylene oxide or ethylene carbonate) or ester-forming derivatives of resorcinol (e.g., resorcinol diacetate). As used herein, the number average molecular weight limitations pertain to the low molecular weight glycols only. Therefore, a compound that is an ester-forming derivative of a glycol and has a number average molecular weight more than 250 can also be used herein, provided that the corresponding glycol has a number average molecular weight of about 250 or lower.

The "dicarboxylic acids" useful for reaction with the above described long- chain glycols or low molecular weight glycols are those low molecular weight (i.e., number average molecular weight of about 300 or lower, or about 10-300, or about 30-200, or about 50-100) aliphatic, alicyclic, or aromatic dicarboxylic acids. The term "aliphatic dicarboxylic acids" used herein refers to those carboxylic acids having two carboxyl groups each attached to a saturated carbon atom. If the carbon atom to which the carboxyl group is attached to is saturated and is in a ring, the acid is referred to as an "alicyclic dicarboxylic acid". The term "aromatic dicarboxylic acids" used herein refers to those dicarboxylic acids having two carboxyl groups each attached to a carbon atom in an aromatic ring structure. It is not necessary that both functional carboxyl groups in the aromatic dicarboxylic acid be attached to the same aromatic ring. Where more than one ring is present, they can be joined by aliphatic or aromatic divalent radicals or divalent radical such as -O- or -SO2-.

The aliphatic or alicyclic dicarboxylic acids useful herein include, without limitation, sebacic acid; 1 ,3-cyclohexane dicarboxylic acid; 1 ,4-cyclohexane dicarboxylic acid; adipic acid; glutaric acid; 4-cyclohexane-1 ,2-dicarboxylic acid; 2-ethyl suberic acid; cyclopentane dicarboxylic acid; decahydro-1 ,5-naphthylene dicarboxylic acid; 4,4'-bicyclohexyl dicarboxylic acid; decahydro-2,6-naphthylene dicarboxylic acid; 4,4'-methylenebis(cyclohexyl) carboxylic acid; 3,4-furan dicarboxylic acid; and mixtures of two or more thereof. In one embodiment, the dicarboxylic acids used herein are selected from cyclohexane dicarboxylic acids, adipic acids, and mixtures thereof.

The aromatic dicarboxylic acids useful herein include, without limitation, phthalic acids; terephthalic acids; isophthalic acids; dibenzoic acids; dicarboxylic compounds with two benzene nuclei (such as bis(p-carboxyphenyl)methane; p- oxy-1 ,5-naphthalene dicarboxylic acid; 2,6-naphthalene dicarboxylic acid; 2,7- naphthalene dicarboxylic acid; or 4,4'-sulfonyl dibenzoic acid); and C1-C12 alkyl and ring substitution derivatives of the aromatic dicarboxylic acids described above (such as halo, alkoxy, and aryl derivatives thereof). The aromatic dicarboxylic acids useful herein may also be, for example, hydroxyl acids such as p-(P-hydroxyethoxy)benzoic acid.

In one embodiment of the compositions disclosed herein, the dicarboxylic acids used to form the copolyetheresters component may be selected from aromatic dicarboxylic acids. In a further embodiment, the dicarboxylic acids may be selected from aromatic dicarboxyhc acids having about 8-16 carbon atoms. In a yet further embodiment, the dicarboxyhc acids may be terephthalic acid alone or a mixture of terephthalic acid with phthalic acid and/or isophthalic acid.

In addition, the dicarboxyhc acids useful herein may also include functional equivalents of dicarboxyhc acids. In forming the copolyetheresters, the functional equivalents of dicarboxyhc acids reacts with the above described long-chain and low molecular weight glycols substantially the same way as dicarboxyhc acids. Useful functional equivalents of dicarboxyhc acids include ester and ester- forming derivatives of dicarboxyhc acids, such as acid halides and anhydrides. As used herein, the number average molecular weight limitations pertain only to the corresponding dicarboxyhc acids, not the functional equivalents thereof (such as the ester or ester-forming derivatives thereof). Therefore, a compound that is a functional equivalent of a dicarboxyhc acid and has a number average molecular weight more than 300 can also be used herein, provided that the corresponding dicarboxyhc acid has a number average molecular weight of about 300 or lower. Moreover, the dicarboxyhc acids may also contain any substituent groups or combinations thereof that do not substantially interfere with the copolyetherester formation and the use of the copolyetherester in the

compositions disclosed herein.

The long-chain glycols used in forming the copolyetherester component of the composition disclosed herein may also be mixtures of two or more long-chain glycols. Similarly, the low molecular weight glycols and dicarboxyhc acids used in forming the copolyetherester component may also be mixtures of two or more low molecular weight glycols and mixtures of two or more dicarboxyhc acids, respectively. In a preferred embodiment, at least about 70 mol% of the groups represented by R in Formulas (I) and (II) above are 1 ,4-phenolene radicals, and at least 70 mol% of the groups represented by D in Formula (II) above are 1 ,4- butylene radicals. When two or more dicarboxyhc acids are used in forming the copolyetherester, it is preferred to use a mixture of terephthalic acid and isophthalic acid, while when two or more low molecular weight glycols are used, it is preferred to use a mixture of 1 ,4-tetramethylene glycol and hexamethylene glycol.

The at least one copolyetherester comprised in the fire-retardant copolyetherester composition disclosed herein may also be a blend of two or more copolyetheresters. It is not required that the copolyetheresters comprised in the blend, individually meet the weight percentages requirements disclosed hereinbefore for the short-chain and long-chain ester units. However, the blend of two or more copolyetheresters must conform to the values described

hereinbefore for the copolyetheresters on a weighted average basis. For example, in a blend that contains equal amounts of two copolyetheresters, one copolyetherester may contain about 10 wt% of the short-chain ester units and the other copolyetherester may contain about 80 wt% of the short-chain ester units for a weighted average of about 45 wt% of the short-chain ester units in the blend.

In one embodiment, the at least one copolyetherester component comprised in the fire-retardant copolyetherester composition disclosed herein is obtained by the copolymerization of a dicarboxylic acid ester selected from esters of terephthalic acid, esters of isophthalic acid, and mixtures thereof, with a lower molecular weight glycol that is 1 ,4-tetramethylene glycol and a long-chain glycol that is poly(tetramethylene ether) glycol or ethylene oxide-capped polypropylene oxide glycol. In a further embodiment, the at least one copolyetherester is obtained by the copolymerization of an ester of terephthalic acid (e.g.,

dimethylterephthalate) with 1 ,4-tetramethylene glycol and poly(tetramethylene ether) glycol.

The copolyetheresters useful in the compositions disclosed herein may be made by any suitable methods known to those skilled in the art, such as by using a conventional ester interchange reaction.

In one embodiment, the method involves heating an dicarboxylic acid ester (e.g., dimethylterephthalate) with a poly(alkylene oxide) glycol and a molar excess of a low molecular weight glycol (e.g., 1 ,4-tetramethylene glycol) in the presence of a catalyst, followed by distilling off methanol formed by the

interchange reaction and continuing the heat until methanol evolution is complete. Depending on the selection of temperatures and catalyst types and the amount of the low molecular weight glycols used, the polymerization may be completed within a few minutes to a few hours and results in formation of a low molecular weight pre-polymer. Such pre-polymers can also be prepared by a number of alternate esterification or ester interchange processes, for example, by reacting a long-chain glycol with a short-chain ester homopolymer or copolymer in the presence of catalyst until randomization occurs. The short-chain ester homopolymer or copolymer can be prepared by the ester interchange either between a dimethyl ester (e.g., dimethylterephthalate) and a low molecular weight glycol (e.g, 1 ,4-tetram ethylene glycol) as described above, or between a free acid (e.g., terephthalic acid) and a glycol acetate (e.g., 1 ,4-butanediol diacetate). Alternatively, the short-chain ester homopolymer or copolymer can be prepared by direct esterification from appropriate acids (e.g., terephthalic acid), anhydrides (e.g., phthalic anhydride), or acid chlorides (e.g., terephthaloyl chloride) with glycols (e.g., 1 ,4-tetramethylene glycol). Or, the short-chain ester homopolymer or copolymer may be prepared by any other suitable processes, such as the reaction of dicarboxylic acids with cyclic ethers or carbonates.

Further, the pre-polymers obtained as described above can be converted to high molecular weight copolyetheresters by the distillation of the excess low molecular weight glycols. Such process is known as "polycondensation".

Additional ester interchange occurs during the polycondensation process to increase the molecular weight and to randomize the arrangement of the copolyetherester units. In general, to obtained the best results, the

polycondensation may be run at a pressure of less than about 1 mmHg and a temperature of about 240-260°C, in the presence of antioxidants (such as 1 ,6- bis-(3,5-di-tert-butyl-4-hydroxyphenol)propionamido]-hexane or 1 ,3,5-trimethyl- 2,4,6-tris[3,5-di-tert-butyl-4-hydroxybenzyl]benzene ), and for less than about 2 hours. In order to avoid excessive holding time at high temperatures with possible irreversible thermal degradation, it is advantageous to employ a catalyst for ester interchange reactions. A wide variety of catalysts can be used herein, which include, without limitation, organic titanates (such as tetrabutyl titanate alone or in combination with magnesium or calcium acetates), complex titanates (such as those derived from alkali or alkaline earth metal alkoxides and titanate esters), inorganic titanates (such as lanthanum titanate), calcium

acetate/antimony trioxide mixtures, lithium and magnesium alkoxides, stannous catalysts, and mixtures of two or more thereof.

The copolyetheresters useful in the compositions disclosed herein can also be obtained commercially from E.I. du Pont de Nemours and Company (U.S.A.) (hereafter "DuPont") under the trade name Hytrel®.

Based on the total weight of the fire-retardant copolyetherester

composition disclosed herein, the at least one copolyetherester may be present at a level of about 20-93.9 wt%, or about 30-85 wt%, or about 40-70 wt%.

Halogen-free flame retardants suitable for use in the compositions disclosed herein may be selected from phosphinates of the formula (III), disphosphinates of the formula (IV), and combinations or polymers thereof

wherein R¹ and R² may be identical or different and each of R¹ and R² is hydrogen, a linear, branched, or cyclic Ci -C₆ alkyl group, or a C₆-Ci₀ aryl group; R³ is a linear or branched C1-C10 alkylene group, a C₆-Ci₀ arylene group, a C₆- C₁₂ alkyl-arylene group, or a C₆-Ci₂ aryl-alkylene group; M is selected from calcium ions, aluminum ions, magnesium ions, zinc ions, antimony ions, tin ions, germanium ions, titanium ions, iron ions, zirconium ions, cerium ions, bismuth ions, strontium ions, manganese ions, lithium ions, sodium ions, potassium ions and combinations thereof; each of m, n, and x is a same or different integer of 1 - 4. Preferably, R¹ and R² may be independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, fe/t-butyl, n-pentyl, and phenyl; R³ may be selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, tert- butylene, n-pentylene, n-octylene, n-dodecylene, phenylene, naphthylene, methylphenylene, ethylphenylene, te/t-butyl phenylene, methylnaphthylene, ethylnaphthylene, fe/t-butylnaphthylene, phenylmethylene, phenylethylene, phenylpropylene, and phenylbutylene; and M may be selected from aluminum and zinc ions. More preferably, the halogen-free flame retardants used herein have a median particle size D₅₀ equal to or greater than about 5 μηη, or equal to or greater than 10 μηη, or equal to or greater than about 15 μηη.

The median particle size D₅₀ is the diameter above and below which respectively 50 wt% of the particles lie. It can be determined by wet laser diffraction measurement

In one embodiment, the halogen-free flame retardants used herein are selected from aluminum methylethylphosphinate, aluminum diethylphosphinate, and combinations thereof. Preferably, the aluminum methylethylphosphinate or aluminum diethylphosphinate used herein has a median particle size D₅₀ equal to or greater than about 5 μηη, or equal to or greater than 10 μηη, or equal to or greater than about 15 μηη.

The halogen-free flame retardants used herein may also be obtained commercially from Clariant (Switzerland) under the trade name Exolit™ OP. Preferably halogen-free flame retardants used herein is obtained from Clariant under the trade name Exolit™ OP1230.

Based on the total weight of the fire-retardant copolyetherester

composition disclosed herein, the at least one halogen-free flame retardant may be present at a level of about 5-30 wt%, or about 7.5-25 wt%, or about 10-25 wt%.

The nitrogen containing compounds suitable for use in the fire-retardant copolyetherester compositions disclosed herein may include, without limitation, those described, for example in U.S. Patent Nos. 6,365,071 ; and 7,255,814.

In one embodiment, the nitrogen containing compounds used herein are selected from melamine, benzoguanamine, tris(hydroxyethyl)isocyanurate, allantoine, glycouril, dicyandiamide, guanidine and carbodiimide, and derivatives thereof.

In a further embodiment, the nitrogen containing compounds used herein may be selected from melamine derivatives, which include, without limitation, (i) melamine cyanurate, (ii) condensation products of melamine, (iii) reaction products of phosphoric acid with melamine, and (iv) reaction products of phosphoric acid with condensation products of melamine. Suitable condensation products may include, without limitation, melem, melam and melon, as well as higher derivatives and mixtures thereof. Condensation products of melamine can be produced by any suitable methods (e.g., those described in PCT Patent Publication No. W09616948). Reaction products of phosphoric acid with melamine or reaction products of phosphoric acid with condensation products of melamine are herein understood compounds, which result from the reaction of melamine with a phosphoric acid or the reaction of a condensation product of melamine (e.g., melem, melam, or melon) with a phosphoric acid. Examples include, without limitation, dimelamine phosphate, dimelamine pyrophosphate, melamine phosphate, melamine polyphosphate, melamine pyrophosphate, melam polyphosphate, melon polyphosphate, and melem polyphosphate, as are described, e.g., in PCT Patent Publication No. WO9839306.

In a yet further embodiment, the at least one nitrogen containing compound comprised in the composition disclosed herein is a melamine cyanurate.

Based on the total weight of the fire-retardant copolyetherester

composition disclosed herein, the at least one nitrogen containing compound may be present at a level of about 0.1 -20 wt%, or about 1 -15 wt%, or about 2-15 wt%.

The composite rubber-based graft copolymers used herein are prepared by grafting silicone/acrylate composite rubber base with one or more vinyl monomers.

The vinyl monomers used herein include, without limitation, vinyl aromatics and/or ring-substituted vinyl aromatics (such as styrene, a- methylstyrene, p-methylstyrene, p-chlorostyrene); methacrylic acid (C C₈) alkyl esters (such as methyl methacrylate, ethyl methacrylate, 2-ethylhexyl

methacrylate, allyl methacrylate); acrylic acid (C C₈) alkyl esters (such as methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate); organic acids (such as acrylic acid, methacrylic acid); vinyl cyanides (such as acrylonitrile and

methacrylonitrile); derivatives (e.g., anhydrides and imides) of unsaturated carboxylic acids (such as maleic anhydride and N-phenyl maleinimide). These vinyl monomers can be used alone or in mixtures of two or more monomers. In one embodiment, the vinyl monomers are selected from styrene, a-methylstyrene, methyl methacrylate, n-butyl acrylate, acrylonitrile, and combinations of two or more thereof. In a further embodiment, the vinyl monomer used herein is methyl methacrylate.

The silicone/acrylate composite rubbers used herein are known and are described for example in U.S. Patent Nos. 5,807,914 or 4,888,388 or EP Patent No. 430134.

The suitable silicone rubber components used herein in the

silicone/acrylate composite rubbers are silicone rubbers having graft-active sites, the production method for which is described for example in U.S. Patent Nos. 2,891 ,920; 3,294,725; 4,888,388, EP Patent Nos. 249964 or 430134.

The silicone rubber component used herein is preferably produced by emulsion polymerization, wherein siloxane monomer units, crosslinking or branching agents, and optionally grafting agents are used.

Dimethyl siloxane or cyclic organosiloxanes having at least 3, or 3-6, ring members may be used as the siloxane monomer units, which may include, without limitation, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyl triphenylcyclotrisiloxanes, tetramethyl tetraphenylcyclotetrasiloxanes,

octaphenylcyclotetrasiloxane.

The organosiloxane monomers can be used alone or in a mixture of 2 or more monomers. The silicone rubber used herein may contain 50 wt% or more, or 60 wt% or more of organosiloxane, relative to the total weight of the silicone rubber component.

Silane-based crosslinking agents with a functionality of 3 or 4, or preferably 4, are may be used as the crosslinking or branching agents, which may include, without limitation, trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, and

tetrabutoxysilane. The crosslinking or branching agents can be used alone or in a mixture of two or more. Tetraethoxysilane is particularly preferred.

The crosslinking agent may be used in a quantity range of between 0.1 and 40 wt%, relative to the total weight of the silicone rubber component. The amount of crosslinking agent is chosen such that the degree of swelling of the silicone rubber, measured in toluene, is 3-30, or preferably 3-25, or more preferably 3-15. The degree of swelling is defined as the weight ratio between the amount of toluene absorbed by the silicone rubber when it is saturated with toluene at 25°C and the amount of silicone rubber in the dry state. The determination of the degree of swelling is described in detail in EP 249964.

Compounds which are capable of forming structures of the following formulae are suitable as the grafting agents: CH₂=C(R⁹)-O-(CH₂)_p-SiR¹⁰ _nO_(3-n)/2 (V)

CH₂=CH-SiR¹⁰ _nO_(3-n)/2 (VI)

HS-(CH2)p-SiR¹⁰nO_(3-n)/2 (VII), in which, R⁹ denotes hydrogen or methyl; R¹⁰ denotes Ci-C₄ alkyl, preferably methyl, ethyl or propyl, or phenyl; n denotes 0, 1 or 2; and p denotes an integer from 1 to 6.

Acryloyloxysiloxanes or methacryloyloxysiloxanes are particularly suitable for forming the aforementioned structure (V) and have high graft efficiency. This ensures an effective formation of graft chains and thus promotes the impact resistance of the resulting resin composition. Particular examples include, without limitation, β-methacryloyloxyethyl dimethoxymethylsilane, γ- methacryloyloxypropyl methoxydimethylsilane, γ-methacryloyloxypropyl dimethoxymethylsilane, γ-methacryloyloxypropyl trimethoxysilane, γ- methacryloyloxypropyl ethoxydiethylsilane, γ-methacryloyloxypropyl

diethoxymethylsilane, δ-methacryloyloxybutyl diethoxymethylsilanes or mixtures thereof.

In accordance to the present disclosure, up to 20 wt% of the grafting agent may be used relative to the total weight of the silicone rubber component.

The silicone rubber can be produced by emulsion polymerization, as described for example in U.S. Patent Nos. 2,891 ,920 and 3,294,725. The silicone rubber is precipitated here in the form of aqueous latex. To this end a mixture containing organosiloxane, crosslinking agent and optionally grafting agent is mixed with water while shearing, for example using a homogeniser, in the presence of an emulsifier based on sulfonic acid, such as for example alkylbenzene sulfonic acid or alkyl sulfonic acid, wherein the mixture polymerizes to form silicone rubber latex. An alkylbenzene sulfonic acid is particularly suitable, as it acts not only as an emulsifier but also as a polymerization initiator. In this case a combination of sulfonic acid with a metal salt of an alkylbenzene sulfonic acid or with a metal salt of an alkyl sulfonic acid is favorable, since in this way the polymer is stabilized during the subsequent graft polymerization.

After polymerization the reaction is terminated by neutralizing the reaction mixture by the addition of an aqueous alkaline solution, for example by the addition of an aqueous sodium hydroxide, potassium hydroxide or sodium carbonate solution.

Suitable polyalkyl (meth)acrylate rubber components used in the silicone/acrylate composite rubbers can be produced from methacrylic acid alkyl esters and/or acrylic acid alkyl esters, a crosslinking agent and a grafting agent. Exemplary methacrylic acid alkyl esters and/or acrylic acid alkyl esters include, C C-8 alkyl esters (e.g., methyl, ethyl, n-butyl, /-butyl, n-propyl, n-hexyl, n-octyl, n- lauryl and 2-ethylhexyl ester) and haloalkyl esters (preferably halo Ci-Cs alkyl esters, such as chloroethyl acrylate, and mixtures of these monomers). n-Butyl acrylate is particularly preferred. Monomers having more than one polymerizable double bond can be used as the crosslinking agents for the polyalkyl (meth)acrylate rubber component of the silicone/acrylate rubber. Preferred examples of crosslinking monomers are esters of unsaturated monocarboxylic acids having 3 to 8 C atoms and unsaturated monohydric alcohols having 3 to 12 C atoms, or saturated polyols having 2 to 4 OH groups and 2 to 20 C atoms, such as ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1 ,3-butylene glycol

dimethacrylate and 1 ,4-butylene glycol dimethacrylate. The crosslinking agents can be used alone or in mixtures of two or more crosslinking agents.

Exemplary grafting agents used herein for the polyalkyl (meth)acrylate rubber component may be allyl methacrylate, triallyl cyanurate, triallyl

isocyanurate, or mixtures thereof. Allyl methacrylate can also be used as the crosslinking agent. Again, the grafting agents can be used alone or in mixtures of two or more grafting agents.

The amount of the crosslinking agent and the grafting agent may be 0.1 -

20 wt%, relative to the total weight of the polyalkyl (meth)acrylate rubber component of the silicone/acrylate rubber.

The silicone/acrylate composite rubber may be produced by first producing the silicone rubber as aqueous latex. This latex is then enriched with the methacrylic acid alkyl esters and/or acrylic acid alkyl esters to be used, the crosslinking agent, and the grafting agent, and a polymerization is performed. A radically initiated emulsion polymerization is preferred, for example by means of a peroxide, azo or redox initiator. The use of a redox initiator system is particularly preferred, specifically a sulfoxylate initiator system produced by combining iron sulfate, disodium methylene diamine tetraacetate, rongalite and hydroperoxide.

The grafting agent used in the production of the silicone rubber causes the polyalkyl (meth)acrylate rubber component to be covalently bonded to the silicone rubber component. During polymerization the two rubber components interpenetrate and thus form the composite rubber, which after polymerization may no longer be able to be separated into its constituents of silicone rubber component and polyalkyl (meth)acrylate rubber component.

In accordance to the present disclosure, the silicone/acrylate composite rubbers used herein may have a glass transition temperature of <10°C, preferably <0°C, or more preferably <-20°C. The glass transition temperatures are determined by dynamic differential scanning calorimetry (DSC) in accordance with the standard DIN EN 61006 at a heating rate of 10 K/min with definition of Tg as the mid-point temperature (tangent method).

Also, the silicone/acrylate composite rubbers used herein may have a median particle size D₅₀ ranging from about 0.05-10 μηη, preferably about 0.06-5 μηη, or more preferably about 0.08-1 μηη.

Further, the silicone/acrylate composite rubbers used herein are

preferably composite rubbers having graft-active sites containing about 1-99 wt%, or about 1 -95 wt%, or about 5-95 wt% of the silicone rubber component and about 99-1 wt%, or about 99-5 wt%, or about 95-5 wt% of the polyalkyl

(meth)acrylate rubber component.

To produce the composite rubber-based graft copolymer used herein, the vinyl monomers are grafted onto the silicone/acrylate composite rubber.

The polymerization methods described for example in EP 249964, EP 430134 and U.S. Patent No. 4,888,388 can be used here.

The graft polymerization takes place for example by the following polymerization method. The desired vinyl monomers are polymerized onto the graft base in the form of an aqueous latex in a radically initiated single- or multistage emulsion polymerization. The graft efficiency should in many cases be as high as possible and is preferably greater than or equal to 10%. The graft efficiency is largely dependent on the grafting agent used. Following

polymerization to form the composite rubber-based graft copolymer, the aqueous latex is poured into hot water, in which metal salts such as for example calcium chloride or magnesium sulfate had been previously dissolved. The composite rubber-based graft copolymer coagulates and can then be separated. In accordance to the present disclosure, about 5-95 wt%, or about 10-95 wt%, or about 10-90 wt% of the one or more vinyl monomers are grafted onto the silicone/acrylate composite rubber, based on the total weight of the composite rubber-based graft copolymers.

The composite rubber-based graft copolymers used herein also are available commercially, for example, from Mitsubishi Rayon Co. Ltd. (Japan) under the trade names Metablen™ S2001 , Metablen™ S2030, Metablen™ SRK200 and etc.

Based on the total weight of the fire-retardant copolyetherester

composition disclosed herein, the at least one composite rubber-based graft copolymer may be present at a level of about 1 -30 wt%, or about 1-20 wt%, or about 5-20 wt%.

The at least one organic UVA comprised in the copolyetherester composition disclosed herein may be selected from benzotriazole based UVAs, benzophenone based UVAs, and mixtures thereof.

The benzotriazole based UVAs useful herein are benzotriazole derivative compounds having benzotriazole backbones. Exemplary benzotriazole based UVAs include, without limitation,

• 2-(2'-hydroxy-5'-methylphenyl)benzotriazole;

• 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole;

• 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole;

• 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chloro benzotriazole;

• 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydro phthalimidomethyl)-5'- methylphenyl)benzotriazole;

• 2,2-methylenebis (4-(1 ,1 ,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2- yl)phenol);

• 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole;

• 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol (TINUVINTM171 , product of BASF, Germany);

• a mixture of octyl-3-[3-tert-butyl-4-hydroxy-5-(chloro-2H-benzotriazole-

2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5- chloro-2H-benzotriazole-2-yl)phenyl] propionate (TINUVINTM109, product of BASF, Germany);

• 2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzortriazole

(TINUVINTM327, product of BASF, Germany);

· 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1 ,1 -dimethylethyl)-4-methyl- phenol (TINUVINTM326, product of BASF, Germany); and

• mixtures of two or more thereof.

The benzophenone based UVAs useful herein are benzophenone derivative compounds having benzophenone backbones. Exemplary benzophenone based UVAs include, without limitation,

• 2,4-dihydroxybenzophenone;

• 2,2'-di-hydroxy-4-methoxybenzophenone;

• 2-hydroxy-4-methoxy-5-sulfobenzophenone;

• bis(2-methoxy-4-hydroxy-5-benzoylphenylmethane); and

· mixtures of two or more thereof.

The at least one organic UVA may be present in the copolyetherester composition disclosed herein at a level of about 0.1 -2 wt%, or about 0.1-1 wt%, or about 0.1 -0.6 wt%,, based on the total weight of the copolyetherester composition.

In one embodiment, the copolyetherester composition disclosed herein comprises about 0.1 -2 wt%, or about 0.1 -1 wt%, or about 0.1 -0.6 wt% of the at least one benzotriazole based UVA.

The at least one HALS comprised in the copolyetherester composition disclosed herein may be one or a combination of two or more HALS.

Suitable HALS may be selected from compounds having the following general formulas:

In these formulas, Ri up to and including R₅ are independent substituents. Examples of suitable substituents include, without limitation, hydrogen, ether groups, ester groups, amine groups, amide groups, alkyl groups, alkenyl groups, alkynyl groups, aralkyi groups, cycloalkyi groups, and aryl groups, in which the substituents in turn may further contain functional groups, examples of suitable functional groups including, without limitation, alcohols, ketones, anhydrides, imines, siloxanes, ethers, carboxyl groups, aldehydes, esters, amides, imides, amines, nitriles, ethers, urethanes, and combinations of two or more thereof.

Suitable HALS may also include polymers or oligomers comprising the

HALS compounds described above.

Suitable HALS are also commercially available, and include, without limitation,

• Good-rite 3034, 3150, and 3159 hindered amine light stabilizers (available from BFGoodrich Corporation, U.S.A.);

• Tinuvin "^vl 770, 622LD, 123, 765, 144, and XT850 hindered amine light stabilizers, Chimassorb™ 1 19FL and 944 hindered amine light stabilizers, and Uvinul™ 4050H hindered amine light stabilizer (available from BASF, Germany);

• Hostavin N20 and N30 hindered amine light stabilizers and

Sanduvor PR31 hindered amine light stabilizer (available from Clariant, Switzerland);

Cyasorb™ UV3346, UV-500, UV-516, and UV-3529 hindered amine light stabilizers (available from Cytec Industries, U.S.A.);

• ADK STAB LA63 and ADK STAB LA68 hindered amine light

stabilizers (available from Adeka Corporation, Japan); and • Uvasil 299 hindered amine light stabilizer (available from Chemtura

Corporation, U.S.A.).

The at least one HALS may be present in the copolyetherester

composition disclosed herein at a level of about 0.1 -2 wt%, or about 0.1 -1 wt%, or about 0.1-0.6 wt%, based on the total weight of the copolyetherester

composition..

The copolyetherester compositions disclosed herein are melt-mixed blends, wherein all of the polymeric components are well-dispersed within each other and all of the non-polymeric ingredients are homogeneously dispersed in and bound by the polymer matrix, such that the blend forms a unified whole. Any melt-mixing method may be used to combine the polymeric components and non-polymeric ingredients of the composition disclosed herein.

Prior art has taught that composite rubber-based graft copolymers can be used as impact modifiers in polymer compositions. And as demonstrated herebelow in the example section, the addition of the composite rubber-based graft copolymers in halogen-free fire-retardant copolyetherester compositions indeed decreases the hardness of the compositions. However, and surprisingly, it is also shown that the retention of strain at break post aging is very much improved with the addition of the composite rubber-based graft copolymers. In addition, in those compositions wherein halogen-free flame retardants having a bigger median particle size D₅₀ (e.g., equal to or greater than 5 μηη) are used, the addition of the composite rubber-based graft copolymers also improves the chemical resistance of the composition. In contrast, such effects were observed when other type of impact modifiers (such as ethylene/methyl acrylate

copolymers or ethylene/butylacrylate/glycidylmethacrylate terpolymer were used). Moreover, the addition of the composite rubber-based graft copolymers also failed to improve the chemical resistance of halogen-free fire-retardant polyesters.

Further disclosed herein are articles comprising one or more component parts formed of the fire-retardant copolyetherester compositions disclosed herein. The articles may include, without limitation, motorized vehicles, electrical/electronic devices, wires, cables, furniture, footwear, roof structure, outdoor apparels, water management system, etc.

In one embodiment, the articles are selected from motorized vehicles. In such embodiments, the fire-retardant copolyetherester compositions disclosed herein may be used to form component parts such as airduct, constant velocity joint (CVJ) boot, etc.

In a further embodiment, the articles are selected from wires and cables. In such embodiments, the fire-retardant copolyetherester composition disclosed herein may be used to form insulating layers or jacket for wires and cables. More particularly, the articles may be selected from wires and cables, which comprise insulating layers and/or jackets formed of the fire-retardant copolyetherester compositions disclosed herein. For example, the article may be an insulated wire or cable, which comprises two or more electrically conductive cores, two or more insulating layers each surrounding one of the electrically conductive cores, and optionally an insulating jacket surrounding the electrically conductive cores and the insulating layers, wherein the insulating layers and/or the insulating jacket are formed of the fire-retardant copolyetherester composition disclosed herein.

EXAMPLES

Material:

• Copolyetherester: copolyetherester elastomer obtained from DuPont

under the trade name Hytrel®3078;

• PBT: polybutylene terephthalate obtained from Chang Chun Plastics Co., LTD. (Taiwan) under the trade name PBT 1 100-211 D;

· GCP-1 : composite rubber-based graft copolymer obtained from Mitsubishi Rayon Co. Ltd. under the trade name Metablen™ S2001 ;

• GCP-2: composite rubber-based graft copolymer obtained from Mitsubishi Rayon Co. Ltd. under the trade name Metablen™ S2030;

• ECP-1 : ethylene/methyl acrylate copolymer obtained from DuPont under the tradename Elvaloy®AC 1300; • ECP-2: ethylene/butylacrylate/glycidylmethacrylate terpolymer obtained from DuPont under the tradename Elvaloy®PTW;

• FR-1 : an aluminum diethylphosphinate based halogen-free flame

retardant having a median particle size D₅₀ equal to about 3 μηη and obtained from Clariant under the trade name Exolit™ OP935;

• FR-2: an aluminum diethylphosphinate based halogen-free flame

retardant having a median particle size D₅₀ equal to about 30 μηη and obtained from Clariant under the trade name Exolit™ OP1230;

• MC: melamine cyanurate obtained from Hangzhou JLS Flame Retardants Chemical Co., Ltd. (China);

• MPP: melamine polyphosphate obtained from Hangzhou JLS Flame Retardants Chemical Co., Ltd.;

• AO-1 : a phenolic primary antioxidant (pentaerythritol tetrakis(3-(3,5-di- tert-butyl-4-hydroxyphenyl)propionate)) obtained from BASF (Germany) under the trade name Irganox™ 1010;

• AO-2: a phosphite ester antioxidant (tris-(2,4-di-tert-butyl-phenyl)- phosphite) obtained from BASF under the trade name Irgafos™ 168;

• CM: color masterbatch obtained from Polyone (U.S.A.) which was

comprised of copolyether ester copolymer resins (obtained from DuPont under the trade name Hytrel® 4056) and color pigments;

• HALS: hindered amine light stabilizer obtained from BASF under the trade name Chimassorb™ 944FD;

• UVA-1 : UV absorber (2-(5-chloro-2H-benzotriazole-2-yl)-6-(1 , 1- dimethylethyl)-4-methyl) obtained from BASF under the trade name Tinuvin™ 326;

• UVA-2: UV absorber (tetraethyl 2,2'-(1 , 4- phenylenedimethylidyne)bismalonate) obtained from Clariant under the trade name Hostavin™ B-CAP. Comparative Examples CE1-CE2 and Examples E1 -E3 In each of the Comparative Examples CE1 -CE2 and Examples E1 -E3, a copolyetherester composition resin was prepared as follows: appropriate amounts of copolyetherester, flame retardants, melamine cyanurate, and other additives (as listed in Table 1 ) were dried, pre-mixed, and melt blended in a ZSK26 twin-screw extruder (purchased from Coperion Werner & Pfleiderer GmbH & Co., Germany) with the extruder temperature set at 190-210°C, the extrusion speed at 350 rpm, and the throughput at 30 kg/hr.

The resins as such obtained were then injection molded (with the process temperature set at about 200°C) into 100x100x2 mm plaques. Using these plaques, the Shore A hardness of the resins were measured in accordance with DIN 53505 and the results are tabulated in Table 1.

Further the 100x100x2 mm molding plaques in each example were die cut in flow direction into dumbbell test bars (in accordance with IS0527-2, 5A).

Using one set of these dumbbell test bars, the tensile strain at break and the tensile stress at break of the resins in each example were measured in

accordance with IS0527 and the results are tabulated in Table 1.

Thereafter, another set of dumbbell test bars in each example were aged in an 121 °C oven for 168 hours before the tensile strain at break and the tensile stress at break thereof were measured. The retention of strain post aging and the retention of stress post aging of the test bars in each example were then calculated and tabulated in Table 1.

Additionally, the chemical resistant properties of the resins in each example were determined using the dumbbell test bars prepared as above.

Briefly, certain chemicals were spread over the neck region of each dumbbell test bar with a circular motion and the chemical coated test bars were conditioned at room temperature for 24 hours with or without a 180° bend. The tensile strain at break and the tensile stress at break of the test bars (chemical treated) were measured. The retention of strain post chemical treatment and retention of stress post chemical treatment of the test bars in each example were then calculated. For those samples where the retention of strain post chemical treatment (with and without bending) and the retention of stress post chemical treatment (with and without bending) were measured as more than 75% were recorded as "Pass" in Table 1. The 19 chemicals used herein are:

• Banana Boat Sunscreen (SPF 30);

• Ivory Dish Soap;

• SC Johnson Fantastik Cleaner;

• French's Yellow Mustard;

• Coca-Cola;

• 70% Isopropyl Alcohol;

• Extra Virgin Olive Oil;

• Vaseline Intensive Care Hand Lotion;

• Heinz Ketchup;

• Kraft Mayonnaise;

• Chlorox Formula 409 Cleaner;

• SC Johnson Windex Cleaner with Ammonia;

• Acetone;

• Artifical Sweat;

• Fruits & Passion Cucina Coriander & Olive Hand Cream;

• Loreal Studioline Megagel Hair Gel;

• Mabelline Lip Polish;

• Maybelline Expert Wear Blush - Beach Plum Rouge; and

• Sebum.

Finally, in each example, insulated conducting wires were prepared using the resins obtained above, wherein each of the insulated conducting wires had a circular cross section and a diameter of about 2 mm, and wherein each of the insulated conducting wires had an insulating jacket made of the copolyetherester composition and encircling conductive core that was made of 91 stranded copper wires. Following UL1581 , the flammability (VW-1 ) of the insulated conducting wires as such prepared were measured and results are tabulated in Table 1 below.

As demonstrated below, with the addition of composite rubber-based graft copolymers (GCP-1 or GCP-2), the retention of strain at break post aging of the resin was very much improved (see E1 or E2 v.s. CE1 or E3 v.s., CE2). In addition, in those embodiments wherein halogen-free flame retardants having a bigger median particle size D₅₀ (e.g., equal to or greater than 5 μηη) were used, the addition of the composite rubber-based graft copolymers also causes the improvements in chemical resistance (see E3 v.s. CE2).

TABLE 1

Comparative Examples CE3-CE15 and Example E5

In each of the Comparative Examples CE3-CE15 and Examples E4, a copolyetherester or PBT composition resin was prepared as follows: appropriate amounts of copolyetherester or PBT, flame retardants, and other additives (as listed in Table 2) were dried, pre-mixed, and melt blended in a ZSK26 twin-screw extruder (purchased from Coperion Werner & Pfleiderer GmbH & Co., Germany) with the extruder temperature set at 190-210°C, the extrusion speed at 350 rpm, and the throughput at 30 kg/hr.

Similarly to the process described above, the composition resin in each example was molded into dumbbell test bars and the chemical resistance properties of each composition were measured (see results in Tables 2 and 3).

Finally, as described above, insulated conducting wires were prepared using the copolyetherester copolymer composition resins obtained above in CE3- CE1 1 and E4 and the flammability (WV-1 ) of the insulated conducting wires as such prepared were measured (see results in Table 2).

As demonstrated herein, in halogen-free fire-retardant copolyetherester copolymer resins, the addition of GCP-1 improved the chemical resistance thereof (see E4 v.s. CE9). However, the addition of other impact modifiers (e.g., ECP-1 and ECP-2) failed to improve the chemical resistance of the same halogen fire-retardant copolyetherester resins (see CE10 and CE1 1 ). Moreover, in halogen-free fire-retardant PBT resins, none of the above impact modifiers (GCP-1 or ECP-1 or ECP-2) could improve the chemical resistance properties thereof (see CE12-CE15).

TABLE 2

TABLE 3

Claims

WHAT IS CLAIMED IS:

1. A fire-retardant copolyetherester composition having improved thermal stability, which comprises:

(a) 20-93.9 wt% of at least one copolyetherester;

(b) 5-30 wt% of at least one halogen-free flame retardant;

(c) 0.1-20 wt% of at least one nitrogen-containing compound; and

(d) 1 -30 wt% of at least one composite rubber-based graft copolymer comprising at least one vinyl monomer grafted onto a

silicone/acrylate composite rubber base,

with the total weight of all components comprised in the composition totaling to 100 wt%, and wherein,

the at least one halogen-free flame retardant comprises at least one selected from the group consisting of phosphinates of the formula (III), disphosphinates of the formula (IV), and combinations or polymers thereof

with R¹ and R² being identical or different and each of R¹ and R² being hydrogen, a linear, branched, or cyclic Ci -C₆ alkyl group, or a C₆-Ci₀ aryl; R³ being a linear or branched C1-C10 alkylene group, a C₆-Ci₀ arylene group, a C₆-Ci₂ alkyl-arylene group, or a C₆-Ci₂ aryl-alkylene group; M being selected from calcium ions, aluminum ions, magnesium ions, zinc ions, antimony ions, tin ions, germanium ions, titanium ions, iron ions, zirconium ions, cerium ions, bismuth ions, strontium ions, manganese ions, lithium ions, sodium ions, potassium ions and combinations thereof; and m, n, and x each being a same or different integer of 1 -4.

The fire-retardant copolyetherester composition of Claim 1 , wherein the at least one halogen-free flame retardant is selected from the group consisting of aluminum methylethylphosphinate, aluminum

diethylphosphinate, aluminum hypophosphite, and combinations or two or more thereof.

The fire-retardant copolyetherester composition of Claim 2, wherein the at least one halogen-free flame retardant is aluminum

methylethylphosphinate or aluminum diethylphosphinate.

The fire-retardant copolyetherester composition of any one of Claims 1 -3, wherein the at least one halogen-free flame retardant has a median particle size D₅₀ equal to or greater than 5 μηη, or equal to or greater than 10 μηη, or equal to or greater than 15 μηη.

The fire-retardant copolyetherester composition of any one of Claims 1 -3, wherein the nitrogen-containing compound is selected from the group consisting of (i) melamine cyanurate, (ii) condensation products of melamine, (iii) reaction products of phosphoric acid with melamine, and (iv) reaction products of phosphoric acid with condensation products of melamine, or the at least one nitrogen-containing compound is melamine cyanurate.

The fire-retardant copolyetherester composition of any one of Claims 1 -3, wherein the at least one vinyl monomer comprised in the composite rubber-based graft copolymers is selected from the group consisting of styrene, a-methylstyrene, methyl methacrylate, n-butyl acrylate, acrylonitrile, and combinations of two or more thereof, or the at least one vinyl monomer is methyl methacrylate.

7. The fire-retardant copolyetherester composition of Claim 6, wherein

composite rubber-based graft copolymers comprises 5-95 wt%, or 10-95 wt%, or 10-90 wt% of the at least one vinyl monomers that are grafted onto the silicone/acrylate composite rubber, based on the total weight of the composite rubber-based graft copolymers.

8. The fire-retardant copolyetherester composition of any one of Claims 1 -3, wherein the silicone/acrylate rubber base comprised in the composite rubber-based graft copolymer comprises 1 -99 wt%, or 1-95 wt%, or 5-95 wt% of a silicone rubber component, with the remaining being a polyalkyi (meth)acrylate rubber component.

9. An article comprising at least one component part formed of the fire- retardant copolyetherester composition of any of Claims 1 -8, preferably the article is selected from motorized vehicle parts and

electrical/electronic devices.

10. The article of Claim 9, wherein the article is selected from insulated wires and cables, and preferably, the insulated wires and cables comprise one or more insulating layers and/or insulating jackets that are formed of the fire-retardant copolyetherester composition of any of Claims 1 -8.