AU700708B2 - Thermoplastic compositions with improved fire resistance - Google Patents

Description

1 The present invention relates to thermoplastic compositions with improved fire resistance and in particular compositions based on polyamide resins and/or on alkenylaromatic (co)polymers. Fire resistance is assessed, on the one hand, by resistance to combustion or to selfignition and, on the other hand, by susceptibility to dripping.

Due to their excellent physical properties, thermoplastic polyamide resins are widely used in many applications in the automobile industry, aeronautics, the electrical field, and the like, but their development is sometimes held back because of their combustibility.

Many proposals have been made in the literature for improving the resistance to combustion of polyamide-based thermoplastic compositions.

Halogenated derivatives such as decabromodiphenyl ether or decabromodiphenyl, optionally in combination with Sb 2 03, have been added but the halogenated compounds generate acid halides which are given off during the manufacture 20 and/or during the use of the compositions in which they are incorporated, thus resulting in risks of corrosion of the equipment and pollution of the environment.

Antimony oxide Sb 2 0 3 is also used in combination with magnesium hydroxide and optionally melamine cyanurate in 25 European Patent Specification EP 571,241 for imparting flameretardancy to thermoplastic polyamide compositions.

is also known to incorporate phosphorus or its derivatives, such as red phosphorus (US 3,778,407), phosphites or phosphates, but these products are difficult to 30 use and confer a reddish tinge on polyamide compositions.

Melamine cyanurate improves the resistance to combustion of polyamides but it is not as effective, weight for weight, as compounds containing a high chlorine or bromine content.

-2 While the above compounds significantly reduce the combustibility of resins in which they are incorporated, their influence on the susceptibility to dripping is low.

According to European Patent Specification EP 169,085 a polyol and melamine cyanurate are simultaneously added to polyamide-based compositions, and this reduces susceptibility to dripping but to a still insufficient extent.

Alkenylaromatic hydrocarbon polymers and copolymers exhibit poor fire resistance and burn easily.

It is known to add flame-retardant agents to these polymers or copolymers and to compositions containing them.

The most commonly used are compounds containing at least one halogen atom, generally bromine.

It is also known, from Japanese Patent Specification JP-A-54/85242, to impart flame-retardancy to polystyrene by means of 3 to 50 parts by weight of melamine cyanurate per 100 parts by weight of polystyrene.

Non-flammable, injection-mouldable thermoplastic S 20 compositions comprising at least 60% by weight of melamine and at most 40% by weight of polystyrene are known from French Patent Specification FR-A-2,096,230.

Compositions comprising from 30 to 80 parts by weight of polystyrene, from 20 to 70 parts by weight of 25 melamine and from 0.05 to 5 parts by weight (expressed as phosphorus) of a phosphorus-containing compound are known :from Japanese Patent Specification JP-A-54/46250.

European Patent Specification EP 438,939 describes thermoplastic compositions containing at least one 30 alkenylaromatic hydrocarbon (co)polymer, at least one nitrogen-containing compound chosen from melamine and melamine isocyanurate, at least one polyol containing at least 4 hydroxyl functional groups per molecule and, optionally, at least one organic ester of phosphoric acid.

The thermoplastic compositions according to the invention comprise -3 antimony oxide Sb 2 O0, melamine cyanurate, one or more polyols.

According to the invention there is, in particular, provided a thermoplastic composition with improved fire resistance, which composition comprises thermoplastic material, Sb 2

O

3 melamine cyanurate and at least one polyol.

Mention is in particular to be made, among the thermoplastic compositions according to the invention, of those based on polyamide resin(s) which contain aliphatic and/or cycloaliphatic and/or aromatic units. These can be obtained by anionic polymerisation of one or more lactams, such as caprolactam, oenantholactam, dodecalactam, or laurolactam, or by hydrolytic lactam polycondensation, either of one or more amino acids, such as aminocaproic, 7aminoheptanoic, 11-aminoundecanoic and 12-aminododecanoic acids, or of one or more salts or mixtures of diamines, such as hexamethylenediamine, dodecamethylenediamine, meta-xylenediamine, bis(para-aminocyclohexyl)methane or trimethylhexamethylenediamine, with diacids, such as iso- and terephthalic, adipic, azelaic, suberic, sebacic and dodecanedicarboxylic acids, or from mixtures of these monomers resulting in copolyamides.

The term "polyamide" (PA) used according to the 25 invention is also understood to mean polyamide-based thermoplastic elastomers (TPE) which are block copolymers, also known as polyetheramides or polyesteramides, the rigid blocks of which are composed of polyamide and the crystallizable flexible blocks of polyether or of polyester.

30 Polyamide according to the invention is also understood to mean mixtures of different polyamides such as those listed above with each other and also their mixtures with other polymers, such as polyolefins, provided with polyamide or polyamides represent at least 50% of the total weight of the mixture. Mention is very particularly to be -4 made of mixtures of polyamide and of polyolefin elastomers which improve the impact strength of polyamides. Mention may be made, as examples of these impact reinforcers, of ethylene and propylene rubbers (EPR), ethylene, propylene and diene rubbers (EPDM), ethylene and vinyl acetate (EVA) copolymers, ethylene-acrylic ester-maleic anhydride terpolymers or terpolymers based on ethylene-acrylic derivative (EAD).

Preferred polyamides includes PA-11, PA-12, PA- 12,12, coPA-6/12 and/or PEBA (polyether block amide).

The polyamides can be plasticized using additives commonly used for this type of modification. They can contain fillers and/or contain various additives, for example additives intended to protect the polyamide against thermal oxidation or thermal/UV degradation, processing aids, such as lubricants, dyes or pigments, and the like.

Mention will also very particularly be made, among the thermoplastic compositions according to the invention, of those based on alkenylaromatic hydrocarbon (co)polymer(s).

The term "alkenylaromatic hydrocarbon polymer" is understood to mean according to the present invention, the products from the homopolymerization of an ethylenically unsaturated aromatic hydrocarbon, such as styrene, alphamethylstyrene, vinyltoluenes, vinylxylenes or methylethylstyrenes.

25 Alkenylaromatic hydrocarbon copolymer is understood to mean according to the pesent invention the products from the copolymerization of a plurality of the alkenylaromatic hydrocarbon monomers or of at least one of these hydrocarbon monomers with at least one other copolymerizable monomer, 30 such as acrylic acid, methacrylic acid, maleic anhydride, alkyl (meth)acrylates in which the alkyl radical comprises from 1 to 8 carbon atoms, acrylonitrile or 1,3-butadiene.

Preferred alkenylaromatic polymers include polystyrene and high-impact polystyrene.

5 Other thermoplastic resins which may, if appropriate, be combined with the alkenylaromatic hydrocarbon polymer or copolymer according to the present invention include in particular: poly(phenylene ether) polyethylene and copolymers of ethylene and of at least one alpha-olefin having from 3 to 8 carbon atoms, it being possible for these last two resins to be made more compatible by means of a grafted or branched ethylene/styrene copolymer, in accordance, for example, with British Patent Specification GB 870,650, homopolymers and copolymers based on esters of acrylic or methacrylic acid, such as poly(methyl methacrylate), copolymers of ethylene and of at least one unsaturated polar comonomer, such as vinyl acetate, alkyl (meth)acrylates, acrylic acid, methacrylic acid or maleic anhydride, polycarbonate.

The thermoplastic material can comprise the alkenylaromatic hydrocarbon polymer or copolymer and other thermoplastic resin in any proportion. It will advantageously comprise from 10 to 90 by weight of one and from 90 to 10 by weight of the other. Preferably, when the 25 thermoplastic material comprises an ethylene-based polymer or copolymer, the alkenyl-aromatic hydrocarbon polymer or copolymer makes up more than 50 by weight in the thermoplastic material.

Other elastomeric resins which may, if appropriate, be combined with the alkenylaromatic hydrocarbon polymer or copolymer include in particular according to the present invention at least one of the following polymers, which may or may not carry polymerized alkenylaromatic hydrocarbon grafts: a polyolefin elastomer, such as a terpolymer of ethylene with at least one alpha-olefin having from 3 to 6 carbon atoms and at least one diene, particularly ethylene- 6 propylene-diene terpolymers, the diene being chosen from conjugated or non-conjugated, linear or cyclic dienes, such as, for example, butadiene, isoprene, 1,3-pentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,9-decadiene, 5-methylene-2-norbornene, 5-vinyl-2-norbornene, 2-alkyl-2,5norbornadienes, 5-ethylidene-2-norbornene, 5-(2-propenyl)-2norbornene, 5-(5-hexenyl)-2-norbornene, bicyclo[2.2.2]octa-2,5-diene, cyclopentadiene, 4,7,8,9tetrahydroindene and isopropylidenetetrahydroindene. Such elastomeric terpolymers which can be used in accordance with the present invention generally comprise between 15 mol and mol% of units derived from propylene and between 0.1 mol and 20 mol of units derived from the diene. Other such elastomeric resins include a styrene/butadiene rubber, a polydiene rubber, such as polybutadiene and polyisoprene, nitrile rubber or ethylene/propylene rubber. These other elastomeric resins are generally used in an amount of at most 20 weight and preferably between 5 weight and 15 weight with respect to the weight of the thermoplastic material.

20 In addition to the preceding resins, the compositions according to the invention can also contain other thermoplastic resins, such as polyolefins, polyurethanes, and the like.

The antimony oxide is generally provided in the 25 form of a fine powder, the particle size of which is of the order of one gm.

o Melamine cyanurate is understood to mean compounds obtainable from the reaction of melamine with cyanuric acid and particularly the compound resulting from the equimolar reaction of melamine with cyanuric acid, it being possible for the latter to be in the enol or ketone form.

Polyol is understood to mean compounds containing at least four alcohol functional groups such as tetrols, such as erythrol or monopentaerythritol (PER) and its polysubstituted derivatives, pentols such as xylitol or arabitol and hexols such as mannitol or sorbitol and its 7 higher homologues.

Compositions according to the invention may be prepared by mixing the different constituents (in the molten state) at a temperature greater than the softening point of the thermoplastic resin. The compositions according to the invention may also be obtained by dry mixing of the constituents.

The incorporation of Sb20 3 melamine cyanurate and polyol or polyols, called the three fire-retardant additives according to the invention, and optional further additives, which are finely divided, in the compositions according to the invention, in particular polyamide-based compositions, is generally carried out by mixing in polyamide resin in the molten state; the mixing temperature is generally between 150 and 300 0 C and preferably between 180 and 230 0

C.

Compositions according to the invention based on an alkenylaromatic hydrocarbon (co)polymer, e.g. a polystyrene (PS) resins, are generally prepared by dry mixing the constituents, if they are all solid at ambient S 20 temperature, in a powder mixer into which the different constituents of the composition are introduced in the powder state, or at most in the form of pearls in the case of the alkenylaromatic hydrocarbon (co)polymers. After mixing for minutes, the mixture is generally ready to use. It is S: 25 also possible to prepare these compositions by mixing the different constituents at a temperature greater than the softening point of the alkenylaromatic hydrocarbon (co)polymer, and of any additional resin as described above if present, for example in the region of 150 to 200°C, in an internal mixer or in an extruder, generally for 1 to minutes. The compositions are then extruded and then converted to homogeneous ready-to-use granules.

A masterbatch or a final product can be prepared.

The masterbatch has the advantage of ensuring good predispersion of the constituents which will be mixed once again during the dilution of the masterbatch in the final 8 resin.

The resin of the masterbatch may be identical to or different from the final resin.

It has been noted that a masterbatch based on a thermoplastic elastomer based on PA was particularly advantageous for subsequent dilutions in many PA resins, among which may be mentioned PA-11, PA-12, PA-12,12, PA-6, PA-6,12 or thermoplastic elastomers based on PA-11, PA-12 or PA-6.

It is possible to produce a masterbatch based on an additional resin or resins and then to dilute it in the final resin. This system is particularly advantageous in the case of PA resins impact strengthened with polyolefinic elastomers: the three fire-retardant additives mixed with the polyolefinic elastomer constitute the masterbatch which may subsequently be diluted in the PA or PS resin.

The three fire-retardant additives according to the invention generally represent from 40 to 60 of the total weight of the masterbatch. In the final, e.g. PA-based, S 20 compositions, they generally represent from 5 to 20 of the total weight of the composition and preferably from 10 to by weight. Each of the three additives according to the invention typically represents at least 15 of the total weight of the three additives. The preferred compositions 25 are those in which each of the three fire-retardant additives represents approximately one third of the total weight of these three additives.

The compositions according to the invention find applications in different fields by conversion into industrial items intended in particular for the automobile, aeronautics, domestic electrical appliance, audio-visual equipment and electrical equipment industries; they are well suited to the production of cable-related components, for example of electrical equipment. They are particularly suited to conversion into moulded, extruded or injected articles, into films, into sheets, into fibres, into 9 composite materials such as coextruded articles or multilayer films, and into powders for coating substrates.

The invention is further illustrated in the following Examples.

Throughout the Examples, the intrinsic viscosity of the PAs is measured at 25 0 C in meta-cresol for 0.5 g of polymer in 100 ml of meta-cresol.

The melting point of the PA resins is measured according to ASTM Standard D 3418 and their Shore D hardness is measured according to ASTM Standard D 2240.

Except where otherwise indicated, the proportions are expressed by weight.

Preparation of masterbatches MB1 to MB8 Various additives, the respective nature and proportions by weight) of which are listed in Table 1, and coPA-6/12 granules are charged to a Melli internal mixer, the vessel of which has been preheated to 100 0 C. The additives represent 50 of the total weight of the masterbatch.

coPA-6/12 (melting point: 130 0 C; Shore D hardness: 60) is marketed by Elf Atochem S.A.

The melamine cyanurate (MC) used is marketed by the Company Chemie-Linz AG.

The monopentaerythritol (PER) used is marketed by the Company Celanese.

Sb 2

O

3 is marketed by the Company Cookson under the Sname Timonox®.

The ammonium polyphosphate (APP) is marketed by the Company Hoechst under the name Exolit 622.

0 The zeolite (ZEO) is marketed by the Company Ceca 30 S.A. under the name of zeolite A4.

The titanium oxide of fine particle size (approximately 1 m) is marketed by the Company Thann Mulhouse under the name RL 10 9r S. e &s e *b .0 5b *0 06

S

4 0 Table 1 Master- MC PER Sb 2 0 3 APP ZEO TiO 2 batch No.

MB1 27.75 5.55 16.7 MB2 35.75 7.15 7.1 MB3 35.75 7.15 7.1 MB4 35.75 7.15 7.1 35.75 7.15 7.1 MB6 35.75 7.15 3.55 3.55 MB7 31.25 12.5 3.125 3.125 MB8 41.7 8.3 Examples 1 to 14 The above masterbatches are then diluted with PA-11 15 (intrinsic viscosity: 1; melting point: 185°C) or PA-12 (intrinsic viscosity: 1; melting point: 175°C), marketed by the Applicant Company, in a Brabender ZSK counterrotating twin-screw extruder (screw speed 60 rev/min; throughput 2 kg/h; temperature profile 180-210-230°C).

The fire resistance is evaluated by measuring the oxygen limit index (OLI) on ISO Standard R178 rods (80 x 10 x 4 mm 3 obtained on a Mining press under the following conditions from *the above samples, and, by way of comparison, from *PA-12 without fire-resistance additives *PA-11 without fire-resistance additives *a composition based on PA-11 according to the teaching of European Patent Specification EP 169,085 containing PER and MC but neither Sb 2 0 3 nor halogenated compound (melting point: 185°C).

11 Injection temperature: 235°C for PA-12 without fire-resistance additives 225°C for composition based on PA-12 215°C for PA-12 without fire-resistance additives 215°C for composition based on PA-11 temperature of the mould: ambient temperature injection cycle: 15 s of injection proper then maintenance under a press for 15 s.

The results of OLI measurement and the concentration of masterbatch by weight) are combined in Table 2.

a* a a *ft 12 Table 2 Example PA Nature Master- Dilution OLI(% No. batch M% IPA-12 MB8 24 2 PA-12 MB1 36 27 3 PA-12 MB7 36 29 4 PA-12 MB2 28 PA-12 MB3 28 6 PA-12 MB6 28 27 7 PA-12 MB7 28 29 8 PA-12 MB7 32 31 9 PA-11 MB8 24 36 PA-12 MB4 28 11 PA-12 MB5 28 12 PA-12 23 13PA-11 26 14 PA-12 36 0 a I a

S

*a.a tWa# a a p.

a.

a a a p 'W a 1 r. i-r~ r:~ to 23 11 1 Compositions containing 86 by weight of PA-12, 20 10 of MC, 2 of PER which are as described above and 2 of various additives are produced under operating conditions identical to those of the samples of Examples 1 to 14.

The characteristics of the additives are as follows: 25 Sb 2

O

3 is identical to that used previously.

The magnesium hydroxide Mg(OH) 2 with a particle size of 1 pm is marketed by the Company Martinswerke under the name Martinfin@H1O.

13 The aluminium hydroxide A1(OH) 3 with a particle size of 1 pm is marketed by the Company Martinswerke under the name Martinal®OL111LE.

The boehmite AO1.OH with a particle size of 1 pm is marketed by the Company Vaw Aluminium.

The silica SiO 2 has a particle size of 1 im.

The dibutyltin dilaurate (DBTDL) is marketed by the Company Merck.

The ortho-boric acid H 3

BO

3 is marketed by the Company Prolabo.

The samples are then shaped in the form of rods in accordance with ISO Standard R178 in a way identical to that of Examples 1 to 14 and their OLI is measured. The results are combined in Table 3.

Table 3 Example No. Additive nature OLI 29.7 16 Sb 2

O

3 34 17 Mg(OH) 2 26.5 20 18 A1(OH) 3 28 19 A10.OH 28.5 20 DBTDL 29 21 Fe 2 O0 29.8 22 SiO 2 29.2 23

H

3B O 3 27.2 Examples 24 to 33 Compositions based on different PA-based resins containing 10 of MC, 2 of PER which are as described above and 2 of Sb 2 03 and, by way of comparison, Sb 2 O0-free a a a a a a.

*aa.

a a a.

14 compositions are prepared.

The PA-12 is identical to that used in Examples 1 to 8 and 10 to 12.

The coPA-6/12 is identical to that used in masterbatches MB1 to MB8.

The PEBA (polyether-block amide), marketed by Elf Atochem SA, is a polyamide-based thermoplastic elastomer in which the polyether blocks are of polytetramethylene glycol (PTMG) and represent 33 of the total weight of the PEBA and the PA blocks are of PA-12 (66 of the total weight of the PEBA) (melting point: 159°C; Shore D hardness: The PP/PA-6 mixture (melting point: 220'C) is a compatabilized alloy marketed by Elf Atochem S.A.

The PA-6 used is a moulding grade and its melting temperature is equal to 218°C.

The samples are then shaped in the form of rods in accordance with ISO Standard R178 in a way identical to that of the samples of Examples 1 to 23 and their OLI and the difference between the OLI of the compositions with and 20 without Sb 2 03 are measured. The results are combined in Table g o 15 Table 4 Example PA resin nature Presence OLI AOLI No. or absence of Sb 2 03 24 PA-12 29.7 25 PA-12 Sb 2 0 3 33.6 +3.3 26 PA-6/12 28.3 27 PA-6/12 Sb 2 0 3 30.2 +1.9 28 PEBA 22.7 29 PEBA Sb203 26.5 +3.8 30 PA-6/PP mixture 20.3 31 PA-6/PP mixture Sb20 3 21.6 +1.3 32 PA-6 24 33 PA-6 Sb 2

O

3 38 +14 Examples 34 to 43 15 Different mixtures according to the invention in which the melamine cyanurate, the monopentaerythritol and/or the Sb 2

O

3 represent 12 of the total weight of each of the mixtures are prepared from the PA-12 described above by direct extrusion of the PA-12 and additives in a Buss 20 Ko-Kneader extruder (screw speed 45 rev/min; throughput kg/h; temperature profile 220-270-220-220-240°C).

The samples are then shaped in the form of rods in accordance with ISO Standard R178 in a way identical to that of the samples of Examples 1 to 33 and their OLI is measured.

C

a a a a.

16 Table Example No. MC PER Sb 2 ,O OLI 34 10.2 1.8 0 29 7.56 0.84 3.6 32 36 4.2 4.2 3.6 37 3.6 3.6 4.8 36 38 3.6 7.2 1.2 32 39 2.4 2.4 7.2 34 0 6 6 28 41 12 0 0 32 42 0 12 0 28 43 0 0 12 27 Prenaration of the masterbatch MB9 a, a a a A masterbatch based on 40 by weight of coPA-6/12 described above, 43 of melamine cyanurate, 8.5 of monopentaerythritol and 8.5 of Sb 2 0 3 is prepared in a Werner® 40 extruder equipped with a corotating twin screw (screw speed 150 rev/min; throughput 24 kg/h; temperature profile 23 0-1 8 0-195-180-180-180-185-190-195-170-190-230°C).

Examples 44 to 52 Different amounts of the above masterbatch are then mixed mechanically with PA-11 or PA-12 with an intrinsic viscosity equal to 1. The degrees of dilution and the PA which is being diluted are shown in Table 6.

17 Table 6 Example No. 0 10 20 30 dilution dilution dilution dilution PA-12 44 45 46 47 L PA-li 48 49 50 51+52* *Example 52 is prepared by direct extrusion of all the constituents without an intermediate masterbatch.

The fire resistance (OLI UL 94) and the mechanical properties of the compositions obtained are evaluated on rods, dum~bbells or sheets according to the operating conditions of the measuring standards used. The results are combined in Table 7.

Table 7 Ex. 44 Ex. 45 S Lx. 4 6 Ex. 4 7 Ex. 4 8 Ex. 49 Ex. SO0 Ex. 51 Ex. 52 EB 383 79 42 17 379 16 22 13 96 TS 64 32 33 39 63 33 32 35 3S FM 1184 1202 1243 1349 1124 1257 1124 1152 1348 Impact 100 nb 14.1 14.7 10.2 100 nb 17.7 11.3 14.1 100 nb at 23 0 Impact 100 nb 15.8 11.4 8.3 100 nb 12.6 9 9 100 nb at -40*C Vicat 173 170 168 164 183 181 179 176 182 point OLI 25 33.7 35.7 34 24.5 32.9 37.4 37.2 39.S 1.6 mm OLI 23.4 31.1 34.9 34.7 25.8 30.2 35.9 35 35.5 3.2 mm UL 94 94V2 94V0 94VO 94VO 94V2 94V2 94V0 94V0 94V0 1.6 mm Il 4 94V2 94V2 94VO 94V0 94V2 94V2 94V2 94V0 94V0 a.

a a *aa.

a a a a.

18 The dynamometric properties EB (elongation at break) and TS (tensile strength) are measured according to ISO Standard R 527 1B.

The flexural modulus (FM) is measured according to ISO Standard 178.

The Charpy impact strength is measured at 23 and 0 C according to ISO Standard 179.

The Vicat point is measured according to ISO Standard 306.

The OLI is measured as above.

The resistance to dripping is evaluated according to NF Standard T 51 0272.

Preparation of masterbatch Under the same operative conditions as for MB9 and with the same proportions of additives, a masterbatch MB10 is prepared in which the PA resin is a PEBA based on PTMG (50 of the total weight of the PEBA) and on PA-12 (50 of the total weight of the PEBA) marketed by Elf Atochem S.A. under the name Pebax MX1205 (melting point 147°C; Shore D hardness Examples 53 to Different amounts of the above masterbatch are then diluted with PA-based resins using an extruder. The fire resistance (UL 94 and OLI) of the samples of Examples 53 to 25 58 is measured according to the standards thus defined above.

Table 8 gives the UL 94/OLI ratio.

Table 8 a Example MB10 Rigid Rigid Plasticized Rigid PEBA PEBA PEBA No. dilution PA-12 PA-11 PA-12 PA-12 1 2 3 30 FG 53 0 V2/24 V2/25 54 10 V2/30 V2/31 V2/24 12.5 V2/26 V2/26 V2/26 56 15 V2/26 57 20 V0/35 V0/36 V2/27 V2/23 V2/27 V2/26 V2/27 58 30 V0/35 V0/37 19 The rigid PA-12 has an intrinsic viscosity equal to 1 and its melting point is equal to 175°C.

The rigid PA-11 has an intrinsic viscosity equal to 1 and its melting point is equal to 185°C.

The PEBA 1 marketed by Elf Atochem S.A. is a thermoplastic elastomer of PEBA (polyether-block amide) type based on PA-12 (80 and on PTMG (20 (melting point 169C; Shore D hardness: 63).

The PEBA 2 marketed by Elf Atochem S.A. is a thermoplastic elastomer of PEBA type based on PA-12 (80 and on polyethylene glycol (PEG) (20 (melting point: 158°C; Shore D hardness: The PEBA 3 marketed by Elf Atochem S.A. is a thermoplastic elastomer of PEBA type based on PA-12 (75 and on PEG (25 (melting point: 169 0 C; Shore D hardness: The fire resistance of the samples of Examples 59 to 62 (diluted in the plasticized PA-12 used previously) is measured according to the incandescent wire technique at 850 0

C

according to CEI Standard 695-2-1; the results are combined in Table 9.

Table 9 a a a 25 a Example No. MB10 dilution Extinction Flame height time (cm) 59 0 28 60 10 15 14 61 20 14 12 62 30 10 qo Some mechanical properties (EB, TS, FM and Charpy impact) of the samples of Examples 59 to 65 are evaluated.

The results are combined in Table The samples of Examples 63 to 65 are 20 compositions which are or are not diluted in PEBA 1 in the proportion of 0 (Example 63) 12.5 (Example 64) (Example Table Example EB TS (MPa) FM (MPa) Impact Impact No. at 23 0 C at -40 0

C

(kJ/m 2 (kj/m 2 59 382 49 438 nb 4.4 352 41 474 45.1 6.1 61 338 37 492 39.2 6.2 62 310 34 507 36.8 6 63 290 nb 64 370 nb 16 380 nb 16.5 S S S S S

SS

S S

S.

S S

S

15 nb not broken 21 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A thermoplastic composition with improved fire resistance, which composition comprises thermoplastic material, Sb 2

O

3 melamine cyanurate and at least one polyol.

2. A composition according to claim 1, wherein the thermoplastic material is based on polyamide resin.

3. A composition according to claim 1, wherein the thermoplastic material is based on PA-11, PA-12, PA-12,12, coPA- 6/12, and/or PEBA.

4. A composition according to claim 1, wherein the thermoplastic material is based on alkenylaromatic hydrocarbon (co)polymer(s).

A composition according to claim 1, wherein the thermoplastic material is based on polystyrene or high-impact polystyrene.

6. A composition according to any one of the preceding claims, wherein the Sb20 3 melamine cyanurate and the polyol or polyols each represent at least 15% of the total weight of these three additives.

7. A composition according to any one of claims 1 to Swherein the Sb 2 03, melamine cyanurate and the polyol or polyols each represent approximately one third of the total weight of these 6:* three additives.

8. A composition according to any one of the preceding 25 claims, wherein the Sb 2 melamine cyanurate and the polyol or polyols represent from 5 to 20% of the total weight of the composition.

9. A composition according to any one of claims 1 to 7 I: I wherein the Sb20 melamine cyanurate and the polyol or polyols 30 represent from 10 to 15% of the total weight of the composition.

10. A thermoplastic composition according to claim 1 substantially as hereinbefore described.

11. A thermoplastic composition according to claim 1 substantially as described in any one of the Examples.

S" 35 12. A process for preparing a composition according to any one of the preceding claims which comprises mixing the constituents at a temperature above the softening point of the thermoplastic material.

Claims (6)

13. A process for preparing a composition according to any one of claims 1 to 11 which comprises dry mixing the constituents.

14. A composition as defined in any one of claims 1 to 11 prepared by the process claimed in claim 13 or 14. A masterbatch for use in preparation of a thermoplastic composition as claimed in any one of claims 1 to 11 which masterbatch comprises a resin, Sb 2 O 3 melamine cyanurate and at least one polyol.

16. A masterbatch according to claim 15 substantially as hereinbefore described.

17. A masterbatch according to claim 15 substantially as described in any one of the Examples.

18. An industrial item obtained by conversion of a composition as claimed in any one of claims 1 to 11.

19. An article formed from a composition as claimed in any one of claims 1 to 11. DATED this TWENTY-SECOND day of JULY 1996 Elf Atochem S.A. Patent Attorneys for the Applicant SPRUSON FERGUSON O* **a 4* a oe Thermoplastic Compositions with Improved Fire Resistance ABSTRACT The present invention relates to thermoplastic compositions with improved fire resistance. According to the invention, thermoplastic resins in particular based on polyamide resin(s) or on alkenylaromatic resin(s), with improved fire resistance, comprises Sb 2 03, melamine cyanurate, and one or more polyols. These compositions can be used for the preparation of moulded, extruded or injected articles, in the form of sheets or films, of composite materials and of powders for coating substrates. [N:\LIBM]05454:AJS