Polymer containing fluorinated polymer and boron compound

Abstract

The flame-retardant properties of polymers with an aromatic main chain can be improved by incorporating therein a fluorine compound in combination with a boron compound.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a polymer-based material which comprises a flame-retardant and optionally a plasticiser and further conventionally used additives

2. Brief Description of the Prior Art

Polymers having an aromatic main chain are materials having good properties which are used in many fields. They are high-melting-point materials and for facilitating their processing a quantity of plasticiser is sometimes added or they are mixed with styrene polymers. It is sometimes desired to improve the impact strength of this type of polymers and for that purpose a rubber is often added, for example, EPDM-rubber or rubber-modified polystyrene. In addition additives for other purpose are also used, if so needed. However, a flame-retardant is conventionally incorporated in all materials.

Polymers having an aromatic main chain are to be understood to mean herein polymers the main chain of which is formed from units having at least one aromatic ring, also including hereto-aromatic rings, which is incorporated in the main chain of the polymer. Not included are polymers, for example, polystyrene, the aromatic ring of which is incorporated in the side chain of the polymer.

The polymers of the above-mentioned group have in common that their combustibility and smoke production generally are slightly smaller than those of polymers, for example, polystyrene and the polyalkenes. Of course, the various polymers of this group do differ mutually in their combustibility and smoke production.

For various important applications, for example, in aeroplanes, a great fire resistance and low smoke production are required. For purposes having stringent combustibility requirements it is therefore sometimes to be preferred not to mix a polymer having an aromatic main chain with a modifying polymer which increases the combustibility. In that case it is further to be preferred to use a plasticiser of a predominantly aromatic nature, if such a plasticeser is to be used.

Various possibilities are available to make polymeric materials flame-retardant For example, the quantity of polymer in the material may be reduced by the addition of inorganic fillers. However, large quantities of this material are necessary which would deteriorate the physical properties of the polymers having an aromatic chain to an unacceptable extent. Another possibility consists in mixing with materials which split off water or carbon dioxide during burning, but such materials cannot be used in polymers having high processing temperatures in which most polymers having an aromatic chain are included. Compounds which comprise phosphorus, chlorine and/or bromine, sometimes with an antimony compound, are conventionally used as flame-retardants in polymer materials. Such flame-retardants produce their effect by poisoning of the flame. This results in an incomplete combustion of the polymer, which in turn usually causes an increase of the smoke emission. Furthermore, the thermal stability of these agents is also restricted, so that they are not suitable as such in polymers which require a high processing temperature. Fluorine-containing compounds have seldom been used as flame-retardants. They often are too stable and in addition it has been found that fluorine is not so effective as a flame poison in the vapour phase as is the case with chlorine or bromine.

Another, scarcely examined, possibility is to achieve the flame-retarding effect by an increase of the yield of carbonised material (remaining weight after combustion); this also implies that the emission of combustible gases and hence of smoke is reduced.

It has been found surprisingly that combination of fluorine compounds and boron compounds form good flame-retardants for polymers of this class and this not only for polymer materials of this type which are used in stringent combustibility requirements, but also for combinations which have to satisfy less stringent requirements and the polymer component of which comprises at least 20% polymer having an aromatic main chain.

SUMMARY OF THE INVENTION

The invention therefore provides a material of the kind described in the opening paragraph which is characterised in that at least 20% of the polymer component has an aromatic chain and the flame-retardant is a mixture of 0.2-15% by weight of at least one fluorine compound and 0.05-10% by weight of at least one boron compound, related to the polymer component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Of course, the flame-retardant may not become operative prematurely, i.e. during the processing of the synthetic material. At the beginning of the examination which has led to the present invention this was verified by means of DSC (Differential Scanning Calorimetry) with reference to the combination of polyvinylidene fluoride and various boron compounds. Polyvinylidene fluoride itself decomposes only above 480.degree. C. and the decomposition is endothermal. However, the thermal stability of this polymer is reduced by the addition of boron compounds. By means of DSC (Differential Scanning Calorimetry) this could be observed as a sharply bounded exothermal reaction which, dependent on the nature of the boron compound chosen, occurs at 280.degree. C. to 470.degree. C.

The reaction temperatures determined by DSC of polyvinylidene fluoride (abbreviated as PVDF) with a few boron compounds are recorded hereinafter.

______________________________________Combination Reaction temperature______________________________________PVDF/sodium tetraborate 290.degree. C.PVDF/zinc borate 300.degree. C.PVDF/boron oxide 320.degree. C.PVDF/lithium metaborate 370.degree. C.PVDF/sodium metaborate 470.degree. C.______________________________________

On the basis of this it is possible to choose a combination which starts to exercise its flame-retarding and smoke-restricting activity at a given desired temperature.

The problem of premature activity of the flame-retardant can easily be avoided, for example, by encapsulating one of the components of the flameretardant or by adding one of the components only towards the end of the processing cycle of the material. In this manner any desired combination of fluorine and boron compound may be used.

As polymers having an aromatic main chain are to be considered in particular polyphenylene ethers, polyphenylene sulphides, polycarbonates, polyether imides, polyether sulphones, polyether-(ether)-ketones, polybenzimidazoles, aromatic polyamides and aromatic LCP's (i.e. aromatic liquid crystalline polymers).

During the development of the present invention polyphenylene ether types and combinations of a few fluoropolymers and a few boron compounds have first been used. Experiments have then been carried out with other polymers having an aromatic main chain and with other fluorine and boron compounds, respectively. In these experiments the general applicabiity of the invention for the indicated field was established.

In case of polyphenylene ethers it is of particular importance to make polyphenylene ether mixtures, without or preferably with a plasticizer, or polyphenylene ether mixtures which comprise only a small quantity of rubber to improve the impact strength, flameretardant. In this manner polymer mixtures are obtained which satisfy stringent fire-safety requirements. The flame-retarding combination according to the invention can also be used successfully with materials comprising, for example, mixtures of polyphenylene ether with highimpact polystyrene or polyoctenylene, combinations which may comprise large or even predominant (up to 80%) quantities of polystyrene or rubber. On the basis of their nature these latter types are much more combustible, but the combustibility thereof is also reduced by the present invention, albeit that herewith not such a large inhibition of the combustibility and smoke production can be achieved as with materials which have to satisfy the stringent combustibility requirements mentioned hereinbefore. In this manner polymer mixtures are obtained which satisfy stringent fire-safety requirements.

This situation applies in general to the polymers having a predominantly aromatic main chain.

As a plasticiser optionally to be used aromatic plasticisers are sometimes to be preferred. For example, polyaromatic esters are to be considered, for example, diphenylphthalate and the like A commercially available plasticiser which has proved to be suitable is pentaerytritol tetrabenzoate (commercial product Benzoflex S552). However, suitable non-aromatic plasticisers may often be used, too.

When polymeric fluorine compounds are used, both an incompletely fluorinated polymer or copolymer, and a completely fluorinated polymer, may be chosen. As not completely fluorinated polymer products may be mentioned polyvinylidene fluoride and copolymers of ethene and tetrafluoroethene, the gross composition of which corresponds approximately to that of polyvinylidene fluoride. A known and suitable completely fluorinated polymer is polytetrafluoroethene. Polyvinyl fluoride also enters into the desired reaction, but does this at a lower temperature, so that in that case the addition of the flame-retardant consisting of two components is never possible as such before or during the processing. However, as already stated hereinbefore, this disadvantage can easily be obviated by encapsulating one of the two components in a material which, in the case of fire, melts easily, or by adding one of the two components only towards the end of the processing. For example, when B.sub.2 O.sub.3 is used, this may be added separately, either at the output of the extruder, or at the injection moulding apparatus.

As will become apparent from the examples hereinafter, however, non-polymeric fluorine compounds are also suitable, for example, simple or complex inorganic fluorine salts.

As boron compounds are to be considered, for example, boric acid, B.sub.2 O.sub.3, and borates, but, as will become apparent from the examples, organic boron compounds are also suitable.

The two components of the present flame-retardant below their reaction temperature are stable substances which are not reactive with respect to plasticisers or other additives present in the polymer component.

The quantities of the fluorine compound and the boron compound to be used are always within the above-mentioned ranges but depend for each individual case on the nature of the polymer component, the nature of the fluorine compound chosen and the nature of the selected boron compound. The optimum quantities can always be determined easily by means of simple experiments.

In case of polyphenylene ethers it may be stated in general that in the choice of polyvinylidene fluoride as a fluorine compound quantities of 0.2-3% by weight of boric acid, B.sub.2 O.sub.3, or borate, related to the polymer component, are suitable. In the case in which polytetrafluoroethene instead of polyvinylidene fluoride is used in this combination, a combination of 3-7% by weight thereof with 1.5-3.5% of B.sub.2 O.sub.3 or borate is suitably used. In the case of boric acid which can ba much more finely distributed, however, smaller quantities will suffice. In that case 1-2% by weight of polytetrafluoroethene and 1-3% by weight of H.sub.3 BO.sub.3 are preferably used.

The material of the invention may moreover comprise one or more additives conventionally used for such materials, for example, fillers, reinforcing fibres, stabilisers, pigments and dyes, plasticisers, mould-release agents, agents to improve the notch impact strength value. If it is desired to add further flame retardants, these preferably are not the conventional flame poisons for example, the comparatively small molecular phosphorus compounds. Stable phosphorus containing compounds having a large molecular weight, however, may be used indeed and these compounds simultaneously serve as plasticisers.

In so far as there exists a sufficient difference between the processing temperature of the material and the reaction temperature of the flameretarding combination, the components of the flameretardant used according to the invention may be incorporated in the basic polymer at any desired instant, for example, by simply mixing the materials before the conventional extrusion or optionally during the extrusion, for example, approximately halfway or near the extrusion head. The addition may also be carried out during the final processing, for example, during injectionmoulding or shaping by extrusion. Furthermore, a master batch may be prepared of one of the two components and may be added to the basic mixture. For the choice between the various possibilities one will be led in general by the said difference between the temperature at which the flame-retardant becomes reactive and the processing temperature of the material.

It is to be noted that the use of phosphonic acid salts as flame-retardants has been described in EP-A-0.245.207. These may be salts with a metal or metalloid from the group IIA, IIB, IIIA and VA of the Periodic Table of the Elements. Although this includes a boron compound, boron is not further mentioned; the preferred salts are aluminium salts. Furthermore, again compounds are concerned which produce their flame-retarding activity by flame poisoning. It is further to be noted that Netherlands Patent Application 6603028 discloses a method of making polyurethane materials flame-retarding by means of a combination of polyvinylidene fluoride, antimony oxide and a compound of an element which is capable of causing the dehydrofluorination of polyvinylidene fluoride to occur at a lower temperature than in the absence of the said compound. Boron compounds are mentioned as one of the possibilities, but are not further explained in the examples.

The following examples only serve to further explain the invention and they are not intended to restrict the invention in any respect. A first series of examples was carried out with a poly-(2,6-dimethyl -1,4- phenylene) ether having an intrinsic viscosity of 46 ml/g in chloroform at 25.degree. C.

EXAMPLE 1

__________________________________________________________________________Composition of materials, parts by weightPolyphenylene ether 80 80 80 80 80 80 80Pentaerytritoltetrabenzoate 20 20 20 20 20 20 20(Benzoflex S552, plasticiser)Polyvinylidene fluoride (PVDF) 0 0.5 0.25 0.5 1 2 1Boron oxide 0 0 0.09 0.18 0.36 0.72 1Flame-retarding properties(according to UL-94, total extinction time, seconds)(10 ignitions, 5 test rods)(1.6 mm) 94 96 106 77 42 20 20(3.2 mm) 53 39 39 24 17 10 10UL-evaluation V1 V1 V1 V1 V0 V0 V0Smoke density in Ds-unitsaccording to ASTM E-662(1.5 min.) 84 56 25 44 30 20 25(4.0 min.) 337 230 284 244 162 87 120(10 min.) 425 316 433 334 380 197 290__________________________________________________________________________

As appears from the above, PVDF itself has already a significant influence on the smoke production. The best combination as regards flame-retarding activity is that with 2% by weight of PVDF and 0.72% by weight of boron oxide.

EXAMPLE 2

The following flame-retardants and other additives were incorporated in a mixture of 85 parts by weight of PPE (=polyphenylene ether) and 15 parts by weight of Benzoflex S552 with the results recorded hereinafter.

______________________________________ UL 94, 1.6 mm total extinctionFlame retardant time, sec______________________________________None 82.52 parts by weight of PVDF + 0.25 parts by 45weight of B.sub.2 O.sub.3 + 0.75 parts by weight of LiBO.sub.22 parts by weight of polytetrafluoroethene 25(PTFE) + 1 part by weight of B.sub.2 O.sub.32 parts by weight of PVDF + 1 part by weight 20of B.sub.2 O.sub.3, 0.5 parts by weight of gas soot(pigment) and 1.5 parts by weight of poly-octenylene rubber (to improve the impactstrength2 parts by weight of PFTE, 1 part by weight of 25B.sub.2 O.sub.3 and 0.5 parts by weight of gas soot______________________________________

EXAMPLE 3

A comparative smoke density test was carried out with the following mixtures and the following results:

______________________________________ Parts by weight______________________________________PPE 85 85 85 85 85Benzoflex 15 15 15 15 15PVDF -- 2 -- 2 --PTFE -- -- 2 -- 2B.sub.2 O.sub.3 -- 0.72 1 1 1Gas soot -- -- -- 0.5 0.5Polyoctenylene rubber -- -- -- 1.5 --Smoke (1.5 min) 100 20 25 10 25density, Ds (4 min.) 370 90 140 60 140 (10 min.) 400 190 200 200 250______________________________________

EXAMPLE 4

A number of tests were carried out again with the plasticizer pentaerytritol tetrabenzoate, abbreviated as PETB in the table below. In this table polyoctenylene rubber is abbreviated as PO.

__________________________________________________________________________PPE 85 85 85 85 85 85 85 85 85 85 85PETB 15 15 15 15 15 15 15 15 15 15 15PVDFPTFE 1 2 3 5 7 2 2 3 3 2B.sub.2 O.sub.3 0.5 1 1.5 2.5 3.5 2 3 3 0 1POLiBO.sub.2Gassoot 0.5UL-941.6 mm (sec) 85 49 .rarw. <20 .fwdarw. 90 <20Evaluation VI .rarw. V-0 .fwdarw. V-1 V-0Smoke density1,5" 100 40 25 16 12 14 11 10 14 110 254" 370 187 140 92 60 60 79 90 71 385 14010" 400 300 200 160 95 107 145 130 109 410 300Char.sup.a) (%) 28 30 31 33 37 36 36 36 36 28 31__________________________________________________________________________PPE 85 80 80 80 80 80 80 80 85PETB 15 20 20 20 20 20 20 20 15PVDF 2 0.5 0.25 0.5 1 2 1 2PTFEB.sub.2 O.sub.3 1 0.09 0.18 0.36 0.72 0.25PO 1.5LiBO.sub.2 0.75Gassoot 0.5UL-941.6 mm (sec) <20 94 96 106 77 42 <20 <20 45Evaluation V-0 V-1 V-1 V-1 V-1 V-0 V-0 V-0 V-0Smoke density1,5" 10 84 56 25 44 30 20 25 204" 60 377 230 284 244 162 87 120 11010" 200 425 316 433 334 380 197 290 230Char.sup.a) (%) 37 28 28 29 30 32 37 36 36__________________________________________________________________________ .sup.a) Residual weight in thermogravimetric analysis (determined at 600.degree. C., under nitrogen, heating rate 200.degree. C./min.).

As will be apparent from the above table, very good results were obtained in the tests with polytetrafluoroethene in combination with B.sub.2 O.sub.3 or borate which was also the case with a number of combinations with polyvinylidene fluoride In the last-mentioned combinations slightly smaller quantities of the two components sufficed.

EXAMPLE 5

The example below indicates that the combination of the invention also leads to better results in the so-called Char test in the case of combinations of PPE and high-impact polystyrene, abbreviated as HIPS in the table below. For comparison, tests are also recorded with the HIPS as the only polymeric component.

______________________________________Parts by weight______________________________________PPE 50 50 30 30 0 0 0HIPS 50 50 70 70 100 100 100PVDF 2 2 2 5B.sub.2 O.sub.3 2 2 2 5Char (%) 18 30 8 23 0 1 3______________________________________

It appears from the table that the present flame-retarding combination showed a significant effect even with a combination of PPE and HIPS consisting predominantly of HIPS, while this was not the case with the HIPS as the only polymeric component. The effect of the flame-retarding combination hence proves to be coupled with the presence of a certain minimum content of PPE in the polymeric component; this minimum is approximately 20%.

EXAMPLE 6

A flame-retardant combination of PTFE and H.sub.3 BO.sub.3 was used. The tested mixture had the following composition:

______________________________________ Parts by weight______________________________________PPE 85PETB 15PTFE 1.5H.sub.3 BO.sub.3 2.2PO 5Gas soot 0.5______________________________________

With this mixture the following results were obtained:

______________________________________UL-94, 1.6 mm, evaluation V0______________________________________Smoke density after 1.5 min. 16 after 4.0 min. 48 after 10 min. 197% Char (see example 5) 36______________________________________

The advantage of the combination PTFE and boric acid is that, due to the fine distribution of the latter, smaller quantities of this combination will suffice than in the case of the other PTFE combinations.

EXAMPLE 7

The following two mixtures:

______________________________________ A B______________________________________PPE 80 80Benzoflex S552 20 20PVDF 0 2Boron oxide 0 0.7______________________________________ were mixed with glass fibres in the weight ratio 70 : 30. In the UL-94 test (2.5mm) the mixture of A and glass fibres was found to be very combustible, while the mixture of B and glass fibres obtained the evaluation VO. It was found that the smoke production in the 70 : 30 mixture of material B and glass fibres had deceased by more than 50% with respect to that of the 70 : 30 mixture of A and glass fibres.

EXAMPLE 8

A great number of tests were carried out with a number of PPE combinations and with various boron compounds and fluorine compounds

__________________________________________________________________________Series A: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17__________________________________________________________________________PPE 85 85 85 85 85 85 85 85 85 60 85 85 85 85 100 100 100PETB 15 15 15 15 15 15 15 15 15 40 15 15 15 15 -- -- --Polyoctenylene 5 5 5 5 5 5 5 5 -- 7 5 5 5 5 -- -- --Boronoxide -- 2 -- -- -- 1 -- -- -- -- -- 2 -- -- -- -- --Boric acid 2 -- -- -- 2 -- 1 1 0.5 2 -- -- -- 2 2 2 2PTFE -- 4 -- 4 4 1 1 0.5 0.3 2 -- -- -- -- -- -- 4CaF.sub.2 -- -- -- -- -- -- -- -- -- -- 4 4 -- -- 4 -- --Potassiumperfluorobutane -- -- -- -- -- -- -- -- -- -- -- -- 4 4 -- 4 --sulphonateUL-94 evaluation V1 V0 V1 V1 V0 V1 V0 V1 V1 V0 V1 V1 V1 V0 V0 V0 V01.6 mmSmoke density in Ds-unitsASTM E6624 min. 370 77 390 365 56 150 79 89 86 60 390 124 360 80 95 97 608 min. 450 110 440 410 89 190 120 140 145 83 405 156 398 110 99 115 76__________________________________________________________________________ Series B Experiment 18 19 20 21 22 23 24 25 26 27__________________________________________________________________________ PPE 30 30 30 30 30 30 30 30 30 30 HIPS 70 70 70 70 70 70 70 70 70 70 Isopropylated triphenyl phosphate 10 10 10 10 10 10 10 -- -- -- (Reofos 50) Tetraphenyl 1.3-phenylenedisphosphate -- -- -- -- -- -- 10 10 10 PTFE (fibre-forming) 0.1 0.2 0.5 -- -- -- -- 0.1 0.5 -- PTFE (non-fibre-forming) -- -- -- -- 0.5 -- 0.5 -- -- 0.5 Boric acid -- -- -- -- -- 0.7 0.7 -- -- 0.7 UL-94 evaluation 1.6 mm BD BD BD V1 BD BD V1 BD V1 V1 Appearance of surface OK OK S S OK OK OK OK S OK (S = splay, i.e. stripe formation on surface, OK = normal)__________________________________________________________________________

In the UL-94 test "BD" means that the material burns and drips.

The following is to be remarked with respect to this test series. In spite of the low content of PPE the Vl-evaluation in the UL-94 test is reached with the combinations of the invention. In addition, a conventional flame-retardant of the phosphate type is also present. Herewith the combinations of the invention moreover provide an anti-drip effect, i.e. the materials do not drip when burning In the technique it is known to add fibre-forming PTFE for this purpose. However, the disadvantage of this is that surface problems, in particular so-called splay, are encountered with too high concentration. However, the anti-drip effect is obtained as well with the combination according to the invention, with non-fibre-forming PTFE, so that no surface problems occur.

__________________________________________________________________________Series C:Test 28 29 30 31 32 33 34 35 36__________________________________________________________________________PPE 85 85 85 85 96 85 85 97 85PETB 15 15 15 15 -- 15 15 -- 15Polyoctenylene 5 5 5 -- -- 5 -- -- 5Boric acid -- 2 2 2 2 2 2 2 2PTFE -- 1.5 -- -- -- -- -- -- --NaBF.sub.4 -- -- 2 2 2 -- -- -- --KPF.sub.6 -- -- -- -- -- 1 1 1 --KZrF.sub.6 -- -- -- -- -- -- -- -- 2UL-94 evaluation V1 V0 V0 V0 V0 V0 V0 V0 V0Smoke density inDs-units, ASTM E6624 min. 366 58 37 30 34 36 30 38 878 min. 440 89 72 76 83 78 72 81 100__________________________________________________________________________

Series D

In this series a few special boroncontaining products were used the syntheses of which are given hereinafter.

A. Tribenzyl borate

A mixture of 186g of boric acid and 990g of benzyl alcohol was heated at 70.degree. C. During the reaction 180ml of a water/benzyl alcohol azeotrope were distilled over. The residue was distilled under a pressure of 0.5-10mm Hg and in this manner 950g of the title compound were obtained as a clear liquid.

B. Oligo (benzyl-bisphenol-A-borate) having a low Tg-value.

34g Of bisphenol-A and 100g of tribenzyl borate were stirred under a pressure of 0.5-10mm Hg at a temperature of 120.degree. C. During the reaction benzyl alcohol (28g) was distilled over. The residue was a clear viscous liquid. The compound has a Tg-value below 0.degree. C.

C. Poly (benzyl-bisphenol-A-borate) having a high Tg-Value

The synthesis was carried out in the same manner as for the product having a low Tg. 100g of tribenzyl borate and 68g of bisphenol-A were used. The residue is poured out after distillation at a temperature of 300.degree. C. After cooling the resulting solid was pulverised. In representative cases the Tg is above 100.degree. C.

The compounds described were incorporated in PPE by dry-mixing, succeeded by extrusion, according to the method used for introducing all the other constituents.

__________________________________________________________________________Series DExperiment 37 38 39 40 41 42 43 44__________________________________________________________________________PPE 79 79 79 79 79 79 79 79PETB 13 13 13 13 13 13 13 13Polyoctenylene 5 5 5 5 5 5 5 5Boric acid 2 -- -- -- -- -- -- --PTFE 1.4 -- 1.4 -- 1.4 -- 1.4 --Tribenzyl borate -- 5 5 -- -- -- -- --Oligo(benzyl-BPA-boraat) -- -- -- 5 5 -- -- --Poly(benzyl-BPA-boraat) -- -- -- -- -- 5 5 5CaF.sub.2 -- -- -- -- -- -- -- 1.4UL-94 evaluation V0 V2 V0 V2 V0 V2 V0 V0(1.6 mm)Smoke density in Ds-unitsASTM E6624 min. 64 320 37 299 56 324 46 778 min. 107 433 142 412 167 411 145 166HDT (deformation temperature) 150 131 131 132 132 135 135 135(.degree.C.)__________________________________________________________________________Series EExperiment 45 46 47 48 49 50 51 52__________________________________________________________________________PPE 92 85 87 82 72 82 82 82Polyoctenylene 5 5 5 5 5 5 5 5Boric acid 2 2 2 2 2 2 2 2PTFE 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4PETB -- 15 -- -- -- -- -- --Polystyrene -- -- 5 10 20 -- -- --Diphenyl sulphone -- -- -- -- -- 10 -- --Minerall oil (Flexon, Exxon) -- -- -- -- -- -- 10 --Indene resin (plasticiser) -- -- -- -- -- -- -- 10(Hercures A150, Hercules)HDT (.degree.C.) 196 147 190 185 176 157 155 158UL-94 evaluation 1.6 mm V0 V0 V0 V1 V2 burns burns burnsSmoke density in Ds-UnitsASTM E6624 min. 55 65 59 75 80 -- -- --8 min. 89 90 110 110 210 -- -- --__________________________________________________________________________ Remarks: The organoborates are slightly less active smoke suppressors than boric acid, but in this connection it should be considered that, as far as the boron content is concerned, 5 parts of organoborate correspond to 1 part of boric acid. The organoborates have the further advantage that they can also serve as plasticisers, as appears from the HDT values.

The following are examples with other basic polymers.

EXAMPLE 9

In this example a polycarbonate was used derived from bisphenol-A and having a viscosity of 52.5 ml/g in methylene chloride at 25.degree. C. In the test series hereinafter 2 types of polytetrafluoroethene commercially available were used, namely the product DLX6000 and the product Polymist F-5A. Both products form particles.

__________________________________________________________________________Experiment 1 2 3 4 5 6 7 8 9 10 11__________________________________________________________________________Polycarbonate 100 99 98 97 98 97 97.5 95 92.5 95 92.5DLX6000 -- -- 2 2 -- -- -- 5 5 -- --Polymist F-5A -- -- -- -- 2 2 -- -- -- 5 5Boron oxide -- 1 -- 1 -- 1 2.5 -- 2.5 2.5UL-94 (1.6 mm) BD BD BD V1 BD V1 BD BD V1 BD V1Average extinction time (sec.) -- -- -- 8 -- 8 -- -- 6 -- 5__________________________________________________________________________ BD means: burns and drips

EXAMPLE 10

Mixtures of polycarbonate and styrene-maleic acid anhydride copolymer are difficult to make flame-retardant. This proves to be very well possible with the system of the invention, as appears from the experiments below.

__________________________________________________________________________ Experiments according Comparative experiments to the invention A B C D 5 6__________________________________________________________________________Bisphenol A-polycarbonate 66.75 54.75 54.75 56.75 66.55 45.75(see example 9)Copolycarbonate of Bisphenol-A 8 20 15 15 -- 15and tetrabromo Bisphenol-A(50/50 ratio)Sodiumtrichlonobenzenesulphonate 0.5 0.5 0.5 0.5 -- --Fibrous polytetrafluoroethene 0.25 0.25 0.25 0.25 0.25 0.25Polymist -- -- -- -- 0.5 1B203 -- -- -- -- 0.2 0.5Sb203 2 2 2 2 -- --SMA.sup.1) 15 15 15 15 15 15Radial teleblockpolymeer (rubber) 7.5 7.5 7.5 7.5 7.5 7.5MBS.sup.2) -- -- -- -- -- 5Tetraphenyl resorcinol diphosphate -- -- 5 5 10 10Izod-notch impact value, J/m 520 480 370 270 470 450UL-evaluation, 1.6 mm V2 V0 V2 V2 V0 V0__________________________________________________________________________ .sup.1) Rubber-modified styrenemaleic anhydride copolymer .sup.2) Graft copolymer of methyl methacrylate, butadiene and styrene to improve the impact strength.

It is to be noted that in the comparative examples the sodium trichlorobenzene sulphonate is used as a component of the flame-retardant combination. As appears from the table the result VO is obtained in the comparative experiments only with a large quantity of copolycarbonate in combination with the said sulphonate and Sb.sub.2 O.sub.3.

EXAMPLE 11

Experiments were carried out with polyphenylene sulphide (PPS) and mixtures thereof with polyphenylene ether (PPE).

______________________________________Experiment 1 2 3 4______________________________________PPS 100 100 50 50PPE -- -- 50 50Boric acid -- 2.2 -- 2.2Polytetrafluoroethene -- 1.5 -- 1.5Smoke density in Ds-units, 12 8 24 12ASTM E-662after 4 min.______________________________________

EXAMPLE 12

Experiments were carried out with aromatic polyether sulphone, a polymer of units of the formula --C.sub.6 H.sub.4 --O--C.sub.6 H.sub.4 SO.sub.2 --. The mixtures and the results are recorded in the table hereinafter.

______________________________________Experiment 1 2 3 4 5______________________________________Polyether sulphone 100 99 99.3 99.8 96.3Boric acid -- 1 -- 1 2.2Polytetrafluoroethene -- -- 0.7 0.7 1.5Smoke density in Ds-units,ASTM E-6624 min. 1 1 1 0 08 min. 3 3 4 1 1Maximum 5 6 5 3 2______________________________________

In this case the interesting result is thus obtained that even with a polymer which in itself produces little smoke upon burning, the said smoke production can even be further reduced by the combination of the present invention.

EXAMPLE 13

Experiments were carried out with aromatic polyetherimide which in itself is not very combustible. It was found that the combination of the invention provides a surprising further reduction of the extinction time in the UL-94 test and of the smoke production, as will be apparent from the experiments below.

As polyetherimides were used for these experiments the commercial products ULTEM.RTM. 1100 and ULTEM.RTM. 1000.

______________________________________Experiment A B C D E F______________________________________ULTEM .RTM. 100 100 100 -- -- --1100ULTEM .RTM. -- -- -- 100 100 1001000Boric acid -- 0.5 1 -- 0.5 1Polytetra- -- 0.35 0.7 -- 0.35 0.7fluoro-ethene(particles-forming)UL-94 (1.6 1.5 0 0 1.6 0 0mm), averageextinctiontime, secondsMax. smoke 13 4 4 60 40 35density ac-cording toASTM E662,DS______________________________________

Claims

1. A polymer composition, which comprises:

a polyphenylene ether polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of the fluroine containing polymer selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene and copolymers of ethylene and tetrafluoroethylene and 0.05-10 percent by weight of an inorganic boron compound.

2. A polymer composition, which comprises;

a polyphenylene sulfide polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.02-15 percent by weight of a fluorine containing polymer selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene and copolymers of ethylene and tetrafluoroethylene and 0.05-10 percent by weight of an inorganic boron compound.

3. A polymer composition, which comprises;

a polyether sulfone polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of a fluorine containing polymer selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene and copolymers of ethylene and tetrafluorethylene and 0.05-10 percent by weight of an inorganic boron compound.

4. A polymer composition, which comprises;

a polyether imide polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of a fluorine containing polymer selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene and copolymers of ethylene and tetrafluoroethylene and 0.05-10 percent by weight of an inorganic boron compound.

5. A polymer composition, which comprises:

a polyphenylene sulfide polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of polytetrafluoroethylene and 0.05-10 percent by weight of boric acid.

6. A polymer composition, which comprises:

a polyether sulfone polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of polytetrafluoroethylene and 0.05-10 percent by weight of boric acid.

7. A polymer composition, which comprises:

a polyetherimide polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame-retardant ingredient, a mixture consisting essentially of 0.2-15 percent by weight of polytetrafluoroethylene and 0.05-10 percent by weight of boric acid.

8. A polymer composition, which comprises:

a polyphenylene ether polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame retardant ingredient, a mixture consisting essentially of 3 to 7 percent by weight of the polymer of a polytetrafluoroethylene and 1.5 and 3.5 percent by weight of a boron compound selected from the group consisting of B.sub.2 O.sub.3 and a borate.

9. A polymer composition, which comprises;

a polyphenylene ether polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame retardant ingredient, a mixture of 1 to 2 percent by weight of polymer of polytetrafluoroethylene and 1 to 3 percent by weight of boric acid.

10. A polymer composition, which comprises:

a polyphenylene ether polymer wherein at least 20 percent of the polymer comprises an aromatic main chain; and as a flame retarding ingredient, a mixture consisting essentially of 0.2 to 15.0 percent by weight of the polymer of polyvinylidene fluoride and 0.2 to 3 percent by weight of an inorganic boron compound selected from the group consisting of boric acid, B.sub.2 O.sub.3 and borate.