NL8001248A - FIRE RETARDANT POLYSTYRENE COMPOSITIONS. - Google Patents

Description

517 / Bos / AS - 1 - r

Fire retardant polystyrene compositions.

The invention relates to fire retardant polystyrene compositions.

For many applications, flame retardants must be included in polystyrene resins, such as polystyrene, styrene-acrylonitrile copolymers (known as SAN resins), acrylonitrile-butadiene-styrene copolymers (known as ABS resins), high impact polystyrene, and the like, in order to provide fire resistance to these resins. Organic compounds containing bromine and / or D chlorine are often used as fire retardants. However, large amounts of flame retardants are often required to obtain polystyrene compositions that meet flame spread specifications and these large amounts are detrimental to other properties of the polystyrene compositions, such as tensile strength and thermal stability.

In order to reduce the amount of flame retardant to be added to such resins, the synergistic action of some additives (or synergistic compounds) which, when used alone, do not act as flame retardants. Organic peroxides have been proposed as synergistic compounds, but they have several drawbacks, particularly with regard to toxicity and stability.

U.S. Patent 4,092,281 discloses certain nitrogen-containing synergists for use in fire retardant polystyrene compositions. The present invention is an improvement over it.

It is therefore an object of the present invention to provide new and improved fire retardant styrene polymer compositions.

Another object of the present invention is to provide new fire retardant polystyrene compositions consisting of a polystyrene resin, a 0 / 0-2 - a halogenated organic fire retardant and a new synergistic compound.

A further object of the invention is to provide polystyrene compositions that overcome the above drawbacks.

Yet another object of the invention is to provide novel synergistic compounds that are highly effective.

Upon achieving the aforementioned eye marks, according to one embodiment of the present invention, a polystyrene composition is provided consisting of a polystyrene polymer, a halogenated organic fire retardant, and a nitrogen-containing organic compound selected from the group consisting of amines, amides and ammonium compounds of 20-40 carbon atoms and their mixtures, which nitrogen containing compound is used in an amount ranging between 0.5 and 50%, based on the weight of the fire retardant.

In another embodiment, the present invention provides a fire retardant composition for use in combination with polystyrene resins, which composition contains a halogenated organic fire retardant and a nitrogen containing organic compound as defined above. ---------------— "Polystyrene resins" include not only styrene homopolymers, such as crystal polystyrene, but also styrene-based copolymers containing a major amount of styrene, such as ABS resins, SAN resins, and high polystyrene grades impact strength containing an elasto more, such as rubber, in an amount ranging up to about 15% by weight. The invention is also applicable to foamed polystyrene, which can be manufactured either by molding expandable polystyrene beads or by extruding mixtures of polystyrene and a foaming agent. It has been found that polystyrene foam produced by extruding polystyrene resins in the presence of a foaming agent together with a nitrogen-containing compound according to the present invention has cells whose average size is significantly lower in comparison to similar polystyrene foams made in the absence of such a nitrogen-containing compound. For example, the size of the cells of a polystyrene foam made in the presence of an ammonium compound of the present invention ranges between about 80-100 µm, while the size of the cells is about 200 µm when the ammonium compound is not used. As a result, the polystyrene foams prepared from the compositions of the present invention have a lower specific gravity and improved self-extinguishing properties and are therefore particularly advantageous for many applications.

The flame retardant is a halogenated organic compound, more particularly a brominated and / or chlorinated organic compound. These halogenated compounds are generally used in an amount such that the halogen content in the polystyrene composition is at least about 0.2%. Levels above about 15% do not bring any benefit. More generally, the halogen content in the final polystyrene composition 25 is between about 0.5 and 10% by weight. This amount mainly depends on the type of halogenated flame retardant; brominated compounds are generally more effective than the corresponding chlorinated compounds and can therefore be used in lesser amounts. These agents and their use are well known in the art. Typical halogenated fire-retardant agents are acetyleentetrabromide, dibromo-tetrachloroethane, tetrachloroethane, pentachloroethane, hexachlorobenzene or hexabromobenzene, tetrabromobutane, poly-35 halogeendivinylderivaten, polyhalogeendivinylethers, perhalogeenpentacyclododecaanderivaten, pentabromo mono-chlorocyclohexane, solid or liquid chlorinated alka-nen, and the like, and mixtures thereof.

The nitrogen-containing organic compounds 800 1 2 48 I according to the invention are synergistic compounds for the halogenated organic compounds used as fire retardants for polystyrene resins. These nitrogen-containing compounds are amines, 5 amides or ammonium compounds with about 20-40 carbon atoms and preferably 26-40 carbon atoms. They are highly effective synergistic compounds and are generally used in an amount ranging from about 0.5 to about 50%, based on the weight of the fire retardant. This amount depends on the type of fire retardant and on the type of nitrogen-containing compound. Generally, the synergistic compound can be used in an amount of between about 0.02 and 2% by weight, based on the polystyrene resin.

The choice of the nitrogen-containing organic compound mainly depends on the price and its availability. Particularly advantageous nitrogen-containing compounds are: (a) secondary and tertiary amines of the general formula N (^) (R2) (R ^) rwhartrr-R - ^ - - - "..." ..... ..... 1-1 r - ° Qri -rost with 9-18 carbon atoms and R2 and

Rgf, which may be the same or different, each represent an alkyl radical of 9-18 carbon atoms; (B) fatty acid amides having more than 25 carbon atoms, more particularly alkylene bisamides, preferably lower alkylene bisamides, and most preferably alkylene bisamides in which the alkylene group contains 1 to 5 carbon atoms, such as ethylene bis (stearyl amide), and 30 such? (c) ammonium compounds such as (a) alkylpyridinium bromides of the formula 1, wherein R 4 represents an alkyl radical of at least 15 carbon atoms, or 35 (c ..) ammonium compounds of the formula 2, in which X is a chlorine or bromine atom or an alkyl sulfate group and R 1 -R 8 each represent a hydrogen atom or a radical having 1-18 carbon atoms, the total number of carbon atoms of the ammonium being 800 1 2 48% - 5 -? ψ bond is at least 20. By way of example, the following preferred ammonium compounds may be mentioned wherein: (1) Rj and methyl groups, Rg is an alkyl-5 group with at least 9 carbon atoms such as a lauryl or stearyl group, Rg is the same group when Rg or a benzyl group and X is a chlorine or bromine atom; (2) Rg and R1 are methyl groups, Rg is a di-alkylphenoxyethoxyethyl group, preferably a diisobutylphenoxyethoxyethyl group, Rg is a benzyl group and X is a chlorine or bromine atom; (3) Rg and R7 are methyl groups, Rg is an alkyl group with at least 4 carbon atoms such as a butyl or hexyl group, Rg is a hydrogen atom and X is an alkyl sulfate group, wherein the alkyl radical contains at least 12 carbon atoms, such as a lauryl or stearyl residue.

The nitrogen-containing organic compounds of the present invention can be incorporated into the resin by intimately mixing the polystyrene resin, the flame retardant, the nitrogen-containing compound and optionally other conventional additives such as dyes, lubricants and the like. The nitrogen-containing compound can also be added to the styrene monomer or monomer and / or polymer mixture before polymerization.

Some flame retardants, more particularly those having high thermal stability, are advantageously used in conjunction with anti-moon oxide. It has been found that the amount of antimony oxide to be added can be reduced by about 50% below that which is conventionally used, without detrimental effect on the fire retardant properties and on the thermal stability of the final polystyrene composition, when a nitrogen-containing compound is included as a synergistic compound in the composition. The amount of antimony oxide, when used, generally does not exceed 7% by weight of the polystyrene resin. This amount depends on the type and amount of the flame retardant, and can generally range from about 2 to 5%. With other fire retardants, more particularly with halogenated aliphatic compounds, the use of antimony oxide is not required. The following examples illustrate the aspects of the present invention without being in any way limiting of the invention.

The self-extinguishing properties of the polystyrene compositions are determined using samples measuring 12.70 x 1.27 x 0.32 cm, according to the following test method:

Each sample is suspended, the largest dimension being vertical and the distance between the bottom end of the sample and the top end of the burner is 0.95 cm. The burner is lit and the flame is 1.9 cm high. Air is pre-mixed with gas to avoid a yellow tip at the top of the flame. This flame is held under the lower end of the sample for a period of 20 seconds. The burner is then removed and the flaming combustion time is measured. Immediately after quenching, the flame is again held under the sample for a period of 10 seconds. The burner is then removed and the flaming combustion time is measured again. The data reported in the examples is the average of 20 consecutive tests (10 samples and 2 determinations for each sample). In the case of foamed polystyrene, the same procedure is used, but the flame is held below the sample only once and for a period of 3 seconds.

Unless otherwise indicated, weight percentages are based on the weight of the total composition.

Example I.

Compositions were prepared from crystal polystyrene, 0.75% pentabromonochlorocyclohexane, 0.05% di-tert-butylhydroxytoluene (BHT), 0.035% zinc stearate and 0.20% of the synergists listed in Table A. The flaming combustion times were as reported in Table A.

800 1 2 48 / 1- tf - 7 - TABLE A.

Synergistic connection Flaming burning time (in sec.)

Stearyl dimethylbenzylammonium-5 chloride 0.42

Distearyl dimethyl ammonium chloride 0.44

Dilauryldimethylammonium bromide 0.23

Diisobutylphenoxyethoxyethyldimethylbenzylammonium chloride monohydrate 0.51 10 Cetylpyridinium bromide 2.07

Ethylene bis (stearylamide) 0.87

Distearylamine 0.54

Trilaurylamine 0.80

Hexyldimethylammonium stearyl sulfate 0.44 A similar composition, but without any synergistic compound, had a flaming combustion time of 11.71 sec.

Example II.

(a) Compositions were prepared from crystal-20 polystyrene, 0.05% BHT, 0.035% zinc stearate, and a flame retardant (for type and amount see Table B) with dilauryldimethylammonium chloride as a synergic compound (see amount for Table B). The results were as reported in Table B.

25

Table B.

800 1 2 48 - 8 - TABLE B.

Flame retardant Quantity Quantity Flaming (%) synergistic combustion compound (%) ding time 5 (in sec.)

Acetylene tetrabranide (0.75%) 0 0.20 0.49

Dibroantetrachloroethane (0.75%) 0 0.20 1.24 10 Penchloroethane (0.75%) 0 0.10 9.17

Tetrabrocobutene (0.75%) 0 0.05 1.58 (b) Compositions were prepared from high impact poly-15 styrene (containing 6% rubber), ----- agent ( For type and amount, see Table C) with dilauryl-dimethylammonium chloride as the synergistic compound (for the amount of Table C) and antimony oxide see 20 s ^ 2 ° 3 ^ for amount of Table Q. The results were as reported in Table C.

TABLE C.

Flame retardant Quantity Quantity Flaming

Sb2C> 3 (%) synergistic combustion time bond (%) (in sec.)

Hexaborobenzene (10%) 3 0.05 1.24

Polybrodiphenyl ether (10%) 3 2.00 0.97

Perchloropentacyclododecane (15%) 3 2.00 1.12 30 Perchloropentacyclododecane (10%) 3 2.00 3.17 800 1 2 48 5 - 9 -

Example III.

Polystyrene was prepared by suspension polymerization of styrene in the presence of pentabromomonochlorocyclohexane (1%) and distearyl dimethyl-5 ammonium chloride (0.15%). The polystyrene beads were washed with water and then stored under vacuum at 75 ° C overnight.

The flaming burning time of samples made from this polystyrene was 0.46 sec.

Example IV.

A composition was prepared from high impact polystyrene (containing 5% rubber), 10% decabromodiphenyl, 3% antimony oxide and 0.5% trilaurylamine.

The flaming combustion time was 1.10 sec.

A similar composition but without the fatty amine had a flaming combustion time of 2.18 sec.

Example V.

Foamed polystyrene samples were prepared by injection molding expandable polystyrene beads (containing pentane as the blowing agent). Pentabromomonochlorocyclohexane (1.5%) and dilauryldimethylammonium chloride (0.2%) were added to these beads.

The flaming combustion time was 0.7 sec.

(compared to 3.21 sec in the absence of the ammonium compound).

Example VI.

Foamed polystyrene samples were prepared by extruding polystyrene in the presence of a blowing agent (containing equal amounts and / 3% pentabromonochlorocyclohexane and 0.1% distearyl dimethyl ammonium chloride.

The flaming combustion time was 1.10 sec.

The cells of the expanded polystyrene had a

average size of 80 pa and its weight I.

3 I

the final product was 35 kg / m. I

A similar product, but prepared without I.

the ammonium compound, had the following properties: 800 1 2 48 - 10 -

Flaming burning time: 4.38 seconds

Cell size: 200 µm

Specific weight: 39 kg / m ^

Example Vl-I.

A composition was prepared from crystal polystyrene, 5% chlorinated alkane (25 carbon atoms and 70% chlorine content), 0.1% BHT, 0.035% zinc stearate and 0.2% distearyl dimethyl ammonium chloride. The flaming combustion time was 10.6 sec.

A similar composition, but without the ammonium compound, had a flaming combustion time of more than 60 sec.

Example VIII.

A composition was prepared from ABS resin 15 (containing 7% butadiene and 17% acrylonitrile), 12% decabromodiphenyloxide, 5% antimony oxide and 2% distearyl dimethyl ammonium chloride. The flaming combustion time was 1.17 sec.

A similar composition, but without the ammonium compound, had a flaming combustion time of 3.48 sec.

Conclusions.

800 1 2 48

Claims (16)

1. Self-extinguishing polystyrene composition consisting of a polystyrene resin, a flame retardant amount of a halogenated organic fire retardant and a nitrogen-containing organic compound, characterized in that the nitrogen-containing organic compound contains 20-40 carbon atoms and consists of (a) a secondary or tertiary amine containing at least one alkyl radical of 9-18 carbon atoms; or 10 (b) a fatty acid amide containing at least 26 carbon atoms; or (c) an ammonium compound selected from (ci) an alkylpyridinium bromide of the formula I, wherein R 1 is an alkyl radical of at least 15 carbon atoms, or (C 1) an ammonium compound of the formula 2, wherein X a chlorine or bromine atom or an alkyl sulfate group and R 1 -R 8 each represent a hydrogen atom or a radical having 1-18 carbon atoms; or 20 (d) a mixture thereof, wherein said nitrogen-containing compound is present in an amount between about 0.5 and 50%, based on the weight of the fire retardant. 2. A composition according to claim 1, characterized in that the nitrogen-containing compound is used in an amount between about 0.01 and 5% by weight of the polystyrene resin. 3. A composition according to claim 2, characterized in that the amount of nitrogen-containing compound is between about 0.02 and 2% by weight of the polystyrene resin. The composition according to any one of claims 1 to 3, characterized in that it further contains anti-moon oxide in an amount not exceeding 35% by weight of the polystyrene resin. o η n 1? 4 8 15. A composition according to claim 4, characterized in that the amount of antimony oxide is between about 2 and 5% by weight of the polystyrene resin. The composition according to any one of claims 5 to 1, characterized in that the polystyrene resin consists of homopolystyrene or a styrene copolymer containing a major amount of styrene. 7. A composition according to claim 6, characterized in that the styrene copolymer consists of an ABS copolymer, a SAN copolymer or a rubber-modified polystyrene. Composition according to any one of claims 1 to 5, characterized in that the polystyrene resin consists of an expanded resin. 9. A composition according to any one of claims 1-8, characterized in that the fire-retardant acetylene tetrabromide, dibromotetrachloroethane, tetrachloroethaTrr-pei ^ af ^ viQ «^ E« ± ii-aJnn hevarhl nm-I ~~ or hexabromobenzene tetrabromobutane, a polyhalodivinyl derivative, a polyhalodiphilyl ether, a perhalopentacyclododecane, pentabromonochlorocyclohexane, a chlorinated alkane or a mixture thereof. 10. A composition according to any one of claims 1-9, characterized in that the nitrogen-containing organic compound consists of a secondary or tertiary amine of the formula N (R ^) (R2) (R ^) t wherein R ^ a hydrogen atom or an alkyl radical with 9-18 carbon atoms and R 2 and R 2, which may be the same or different, each represents an alkyl radical with 9-18 carbon atoms. Composition according to any one of claims 1 to 9, characterized in that the nitrogen-containing organic compound consists of an alkylene bis fatty acid amide. 80 0 1 2 48 - 13 - 12. A composition according to any one of claims 1-9, characterized in that the nitrogen-containing organic compound consists of an ammonium compound of the formula 2, wherein X is a chlorine or bromine atom or an alkyl sulfate group, wherein (1) Rg and R7 are methyl groups, Rg is an alkyl group with at least 9 carbon atoms, Rg is the same group as Rg or is a benzyl group and X is a chlorine or bromine atom; or 10 (2) are Rg and methyl groups, Rg is a dialkylphenoxyethoxyethyl group, Rg is a benzyl group and X is a chlorine or bromine atom; or (3) Rg and R 1 are methyl groups, Rg is an alkyl group with at least 4 carbon atoms, Rg is a hydrogen atom and X is an alkyl sulfate group, wherein the alkyl radical contains at least 12 carbon atoms. 13. A composition according to claim 12, characterized in that Rg in the compound (1) is a lauryl or stearyl group. 14. A composition according to claim 12, characterized in that Rg in the compound -T3T is a butyl or hexyl group and the alkyl radical of the alkyl sulfate group is a lauryl or stearyl radical. 15. A composition according to any one of claims 10-14, characterized in that the nitrogen-containing compound consists of stearyl dimethylbenzyl ammonium chloride, distearyl dimethyl ammonium chloride, dilauryl dimethyl ammonium bromide, diisobutylphenoxyethoxyethyl dimethylbenzylammonium chloride monohydrate, cetybrethyl, pyridinium ethylidenylamide, trilaurylamine, hexyl dimethyl ammonium stearyl sulfate or dilauryl dimethyl ammonium chloride. 16. Fire retardant composition for use in combination with polystyrene resins, consisting of a halogenated organic fire retardant and a nitrogen containing organic compound, having 800 1 2 48 - 14 - characterized in that the nitrogen containing compound contains 20-40 carbon atoms and consists of (a) a secondary or tertiary anine containing at least one alkyl radical of 9-18 carbon atoms; or 5 (b) a fatty acid amide containing at least 26 carbon atoms; or (c) an ammonium compound selected from (c ^) an alkyl pyridinium bromide of the formula 1, wherein an alkyl radical has at least 15 carbon atoms, or (c ..) an ammonium compound of the formula 2, wherein X is a chlorine or bromine atom or an alkyl sulfate group and R 1 -R 8 each represent a hydrogen atom or a radical having 1-18 carbon atoms, or 15 (d) a mixture thereof, wherein this nitrogen-containing compound is present in an amount between about 0.5 and 50%, based on the weight of the flame retardant. 80 0 1 2 48 V <+) \ ^) BÏ 1 R „► R6-N <+> -R8 X 'R7 LABOFINA S.A. 800 1 2 48