GB2028833A

GB2028833A - Fire-resistant halogen- containing polymer compositions

Info

Publication number: GB2028833A
Application number: GB7929188A
Authority: GB
Original assignee: Rhone Poulenc Industries SA
Current assignee: Rhone Poulenc Industries SA
Priority date: 1978-08-24
Filing date: 1979-08-22
Publication date: 1980-03-12
Also published as: NL7906366A; NO160930C; CH642090A5; SE7907052L; JPS638137B2; NO792734L; FR2434188B1; GR67233B; GB2028833B; FR2434188A1; SE445354B; IT7925169A0; DE2933806A1; BE878402A; JPS5548237A; IT1123530B; NO160930B

Abstract

Halogen-containing polymers, e.g. PVC, exhibit reduced inflammability and reduced fume density when they contain a hydroxylic magnesium aluminosilicate as a flameproofing additive. A secondary flameproofing additive, e.g. CuO, Cu2O or CuSO4, may be present, and may be deposited on the aluminosilicate.

Description

SPECIFICATION Compositions of halogen-containing polymers, which exhibit improved behaviour on exposure to fire The present invention relates to compositions based on halogen-containing polymers, which exhibit improved behaviour when exposed to fire.

It is known that halogen-containing polymers and especially polyvinyl chloride, exhibit good selfextinguishing properties due to the presence of hydrochloric acid in the thermal decomposition gases.

However, during a fire, the density of the fumes, and the evolution of toxic gases, are considered to be at least as dangerous as the propagation of the flames. The relative inflammability and the evolution of fumes can be explained by the presence, in the materials based on halogen-containing polymers, of volatile organic compounds, and by the formation of aromatic and/or aliphatic compounds during the pyrolysis. A study of the kinetics of thermal decomposition of industrial mixtures based on polyvinyl chloride shows that the appearance of inflammable volatile materials and of hydrochloric acid are not simultaneous.

To achieve improved behaviour of these materials when exposed to fire, it is necessary on the one hand to control the presence of hydrochloric acid in the decomposition gases throughout the duration of the exposure to heat and, on the other hand, at the same time to modify the pyrolysis process so as to produce the minimum of inflammable volatile gases which are capable of forming fumes. This modification entails a simultaneous reduction in self-ignitability, in density and in the rate of evolution of the fumes.

In order to solve the problem of the fumes, it has been proposed to incorporate zinc oxide or zinc salts into the compositions; and the synergistic effect of zinc with conventional fillers, such as calcium oxide or carbonate, magnesium oxide or carbonate, or alumina, which are capable of forming chlorides or oxychlorides during the pyrolysis, has been highlighted. These fillers have little effect on the selfextinction time and frequently increase the rate of evolution of fumes, and hence the density of fumes reached within a given time. The main disadvantage of the zinc salts is a high destabilising action, so that they cannot be used in sufficient amount in rigid (unplasticised) compositions which require processing temperatures which can be as high as 250or.

United States Patent 3,869,420 discloses plasticised compositions which exhibit a simultaneous reduction in the inflammability and in the evolution of fumes by virtue of the addition of a "reactive modifier", for example hydrated alumina, magnesium oxide, hydroxide or carbonate, or Dawsonite but it is necessary to use a phosphate plasticiser.

The present invention aims to avoid the abovementioned disadvantages and relates to compositions based on halogen-containing polymers, especially on polyvinyl chloride, which exhibit a simultaneous reduction in inflammability and in the production and rate of evolution of fumes, and which can be used in the usual conversion processes using temperatures which can be as high as 2500C.

According to the invention, the compositions are characterised in that they contain 0.5 to 100 parts by weight of hydroxylic magnesium aluminosilicate per 100 parts by weight of resin.

The magnesium aluminosilicates can 6e ae7inea by the empiricai general formula (represented in terms of the oxides) x MgO y Awl203 z SiO2 n H,O, in which x, y and z represent the number of mols of the oxides and n the number of mols of water of crystallisation. In the magnesium aluminosilicates which can be used according to the present invention, x, y, z and n represent values which are preferably such that the content of MgO is from 3 to 30% by weight, the content of Awl203 is from 10 to 20% by weight, the content of SiO2 is from 30 to 60% by weight and the content of water of crystallisation is from 2 to 10% by weight.In other words the aluminosilicates must be hydroxylic in the sense that they contain water of crystallisation. These components can optionally be combined with oxides of iron and/or zinc oxide, chemically bonded, in an amount of less than 1 5%.

The magnesium aluminosilicates which correspond to the above definition exist in the natural state. It is possible to use phyllitic clay-type minerals having a structure of the mica type or of the chlorite type. Amongst the micas having the indicated composition, examples which may be mentioned are the vermiculites (aluminous talc), the montmorillonites and bentonites (pyrophilites) and the magnesium-containing micas such as glauconite, phlogpite and biotite, as well as attapulgite.

These materials are preferably used in the form of fine powders having a mean particle size of less than 200 y and more advantageously less than about 10 y. More especially, the commercial products in a "micronised" form are used.

The term "halogen-containing polymer" as employed herein is used in its broad sense and, in particular, covers any type of vinyl chloride homopolymer or vinylidene chloride homopolymer, copolymers or their mixtures, regardless of the method of preparation such as bulk polymerisation, emulsion polymerisation, suspension polymerisation or micro-suspension polymerisation, and regardless of molecular weight. The copolymers are, in particular, copolymers of vinyl chloride and vinyl acetate, of vinyl chloride and acrylic or methacrylic acid or ester, and of vinyl chloride and monofunctional of difunctional allyl monomers. The copolymers usually contain at least 50% by weight of vinyl chloride.

The term "halogen-containing polymer" as used herein also includes the chlorinated polyolefines, such as chlorinated polyethylene and chlorinated polypropylene, polychloroprene, chlorosulphonated polyolefines and chlorinated paraffins, and mixtures of such halogen-containing polymers with resins which do not contain halogen.

The compositions can be of the rigid, semi-rigid or flexible type and can contain the usual ingredients for such compositions, and in particular, fillers, stabilisers, opacifying agents and/or lubricants, processing adjuvants, plasticisers and antioxidants.

The precise amount of the magnesium aluminosilicates used may be varied to give optimum results with the particular composition, this being dependent on, in particular, the nature and amount of any plasticiser present as well as the desired level of protection. One of skill in the art will appreciate how the amounts for each particular case should be decided. In general terms, up to, say, 10 parts of magnesium aluminosilicate can be introduced into compositions of the rigid type and up to, say, 100 parts into compositions of the plasticised type.

According to an advantageous embodiment of the present invention, the reduction in fumes and in the tendency to flame propagation can be improved by additional incorporation of additives derived from metals, such as antimony trioxide, or the oxides, hydroxides and salts of antimony, zinc, copper, molybdenum, nickel, cobalt, vanadium, tin, iron, lead, barium, cadmium and bismuth. As salts, the sulphates, borates, acetates, chromates, tungstates and acetylacetonates may be mentioned as examples.

These additives can be incorporated separately at the same time as the other adjuvants. They can also be mixed with the aluminosilicates or with certain of the other adjuvants of the composition; they thus form an adjuvant composition which is subsequently incorporated into the resin.

A particularly valuable embodiment consists in depositing the secondary flameproofing additives, by impregnation, on the magnesium aluminosilicate which serves as a carrier. It is thus possible to obtain valuable results with amounts of additives which are markedly less than those which would have to be used when employing a powder mixture. To carry out the impregnation in practice it suffices to disperse the aluminosilicate, by mechanical stirring, in a solution of the chosen metal salt or salts and then to remove the solvent by evaporation. The amount of metal additives deposited or used in the mixture can vary within wide limits, depending on the nature of the metal and the composition employed, and can be as much as 50% by weight relative to the weight of the aluminosilicate.

The compositions according to the invention can be used in accordance with all the conventional processing techniques, such as injection-moulding, extrusion calendering and compression moulding, for the manufacture of moulded articles, tubes and fiameproofed articles.

The following Examples further illustrate the present invention.

EXAMPLES 1 TO 4 The following composition is prepared: 100 parts of a vinyl chloride bulk polymer having a viscosity index of 100 (LUCOVYL GB 1 50), 0.5 part of dibasic lead stearate, 0.5 part of tribasic lead sulphate, 0.5 part of calcium stearate, 0.5 part of PA 520 wax and 0.2 part of titanium dioxide.

x parts of a magnesium aluminosilicate are added to this composition, which serves as a blank.

In each test, all the powder products are mixed in a high speed mixer of the Papenmeier type at a temperature of up to 9O1000 C.

Sheets of about 5 mm thick are moulded with the compositions thus prepared.

The following tests are carried out on specimens cut from these sheets: Heat stability: DHC (dehydrochlorination) The time (in minutes) required for the appearance of HCI at 2000 C, according to the CSTB (Centre Scientifique et Technique du Batiment) method.

Limiting oxygen index: LOI Opacity of the fumes: in accordance with French Standard Specification NF 51,073 - test temperature: 4500C and 6500 C. The result (the mean of 3 samples) is expressed as the total amount of fumes emitted in conventional units UFt, and in accordance with the fume chamber method of the National Bureau of Standards: NBS.

The tests are carried out with and without a flame on specimens of size 76.2 x 76.2 x 5 mm. The following results are recorded: SOI,: Smoke Obscuration Index at 4 minutes OD 90: optical density at 90 seconds CMD: corrected maximum density The results are shown in Table I. Compared with the blank, an increase in the heat stability and better behaviour on exposure to fire, both as regards inflammability and as regards the amount and rate of evolution of fumes, are observed.

EXAMPLES 5 TO 9 These examples illustrate the action of a secondary additive in combination with a magnesium aluminosilicate.

The blank composition of the preceding Examples is used, and x parts of the magnesium aluminosilicate and y parts of the secondary additive are added thereto. In Example 6, the vermiculite is impregnated beforehand with an aqueous copper sulphate solution in an amount of 10 parts of sulphate (expressed as solids) per 100 parts of vermiculite. After drying, the vermiculite has a mean particle size of5,u.

The results are expressed in Table II. Compared to the blank, a behaviour on exposure to fire which is substantially improved in all the values measured is found. Impregnation of the carrie makes it possible to reduce the amount of copper salt in the ratio 5/1 and to avoid the destabilisation which is detrimental to the processing of the composition.

EXAMPLES 10 AND 1-1 The blank composition of the preceding Examples is used, but 1.5 parts of calcium carbonate are added and the resulting composition used as the blank. In a first experiment, 2 parts of vermiculite are added. In a second experiment, 2 parts of vermiculite impregnated with 10% (by weight) of copper sulphate and having a mean particle size of 5 u are added. The results are expressed in Table Ill.

Comparison of the blank with the blank from Table I indicates that the calcium carbonate increases the rate of evolution of fumes (NBS). Examples 10 and 11 show the improvement in the behaviour on exposure to fire in respect of all the values measured.

EXAMPLES 12 AND 13 A composition is prepared in accordance with the formulation shown below: Polyvinyl chloride (Lucovyl GB 11 50) 100 parts Tribasic lead sulphate 0.5 part Dibasic lead stearate 0.5 Neutral lead stearate 0.2 Calcium stearate 0.5 PA 520 wax 0.5 Titanium oxide 0.2 Calcium carbonate 1.5 parts The following re added to this cdnipositidri: Example 12 - 1.5 parts of vermiculite impregnated with 10% of copper sulphate Example 13 -3 parts of attapulgite impregnated with 30% of copper sulphate The products are homogenised and the composition is used to manufacture a tube 2.5 mm thick by extrusion on a KESTERMAN K 86-16 D machine.The operating conditions are as follows: Temperature head 1800C die 190 to 2000C Metering speed: 22 rpm Screw speed: 18 rpm Torque: 460 mkg Throughput: 1 25 kg/hr.

The inflammability test and fume density test in a NBS chamber are carried out on a specimen taken from the tube, and the results (Table IV) are compared with tube manufactured under the same conditions, using the same composition but without aluminosilicate.

EXAMPLE 14 A plasticised type of composition is prepared in accordance with the formulation shown below, which serves as a blank.

Emulsion polyvinyl chloride (viscosity index: 130) 100 parts Octyl trimellitate 45 Lead stabiliser 12 Antioxidant 2 5 parts of attapulgite impregnated with 10% of copper sulphate are added.

The following results are obtained.

NB S LOI UFt | with flame 500 C 900 C CMD Blank 25.6 2.2 4.1 > 1,000 14 26.8 2 2 601

EXAMPLE 15 The octyl trimellitate of the formulation according to Example 14 is replaced by 37 parts of poly(propylene glycol adipate). The following result is obtained:

NBS LOI UFt with flame 500 C 900 C CMB Blank 30.2 4 5.5 659 15 32.2 2.6 1.4 580 TABLE I

NBS UFt without flame with flame Additive x DHC LOI 450 C 650 C SOI4 OD 90 SOI4 OD 90 CMD Blank 14 48.5 2.43 1.06 68 3 968 153 1 Vermiculite 0.5 30 62 2.05 0.95 2 Vermiculite 1.5 28 #70 1.65 0.70 57 8 802 125 725 3 Vermiculite 2 30 #70 1.70 0.67 4 616 63 810 4 Attapulgite 2 22 54 2.25 0.84 52 2 622 98 900 TABLE II

NBS UFt without flame with flame 1st 2nd Examples additive x additive y DHC LOI 450 C 650 C SOI4 OD 90 SOI4 OD 90 CMD Blank None None 14 48.5 2.43 1.06 68 3 968 153 5 None CuSO4 1 10 60 1.56 0.52 63 5 440 51 542 6 Vermiculite 2 CuSO4 0.2 23 63 2.00 0.57 48 5 319 53 504 (impregnated) 7 Vermiculite 2 CuO 2 24 > 70 1.65 0.52 28 3 286 37 524 8 Vermiculite 2 Cu2O 2 28 > 70 1.31 0.60 46 2.5 201 22 516 9 Attapulgite 2 CuO 2 20 65 1.82 0.59 39 3 267 36 515 TABLE Ill

NBS UFt without flame | with flame DHC LOI 4500C 65000 8014 OD 90 8014 OD 90 CMD Blank 29 50 2.40 1.08 81 2 1148 234 > 900 10 28 55 2.08 0.80 51 2 550 85 614 11 26 58 1.86 0.66 ~ 50 5 409 56 575 TABLE IV

NBS without flame with flame LOI SOI, OD 90 OMD SOI, OD 90 CMD 12 57 ' 45 3 390 264 35 454 13 68 288 461 Blank 49 86 1 394 787 118 636

Claims

1. A composition which comprises a halogen-containing polymer and 0.5 to 100 parts by weight of a hydroxylic magnesium aluminosilicate per 100 parts by weight of polymer in the composition.

2. A composition according to claim 1 in which the magnesium aluminosilicate contains, expressed as weight of oxides, 3 to 30% of magnesium, 0 to 20% of aluminium, 30 to 60% of silicon and 2 to 10% of water of crystallisation and optionally, chemically bonded oxides of iron and/or zinc in amount of up to 15%.

3. A composition according to claim 1 or 2, which contains as additive, an oxide, hydroxide or salt of zinc, copper, molybdenum, nickel, cobalt, vanadium, tin, iron, lead, barium, cadmium, antimony or bismuth.

4. A composition according to claim 3 in which the additive is a copper sulphate.

5. A composition according to claim 3 or 4, in which the additive is present deposited on the magnesium aluminosilicate.

6. A composition according to any one of claims 3 to 5, in which the amount of additive is from 0.1 to 50% by weight relative to the hydroxylic magnesium aluminosilicate.

7. A composition according to any one of claims 1 to 6, in which the mean particle size of the hydroxylic magnesium aluminosilicate less than 10 .

8. A composition according to any one of claims 1 to 7, in which the halogen-containing polymer is å polyvinyl chloride.

9. A composition according to any one of claims 1 to 8 in which the halogen-containing polymer is an unplasticised polyvinyl chloride and the composition contains 0.5 to 10 parts by weight of hydroxylic magnesium aluminosiiicate per 100 parts by weight of polymer.

10. A composition according to claim 9, which contains 0.5 to 5 parts by weight of additive as defined in claim 3 or 4.

11. A composition according to any one of claims 1 to 8 in which the halogen-containing polymer is a plasticised polyvinyl chloride.

12. A composition according to claim 11, which contains 0.1 to 50 parts by weight of additive as defined in claim 3 or 4.

1 3. A composition according to any one of the preceding claims in the form of a moulded article.

14. A composition according to claim 1 substantially as described in any one of Examples 1 to

1 5.

1 5. A hydroxylic magnesium aluminosilicate having deposited thereon an oxide, hydroxide or salt of zinc, copper, molybdenum, nickel, cobalt, vanadium, tin, iron, lead, barium, calcium, antimony or bismuth.

16. An aluminosilicate according to claim 15 having one or more of the features of claims 2, 4 and 7.