GB2048276A

GB2048276A - Fire-Retardant Polystyrenic Compositions

Info

Publication number: GB2048276A
Application number: GB8004433A
Authority: GB
Original assignee: Labofina SA
Current assignee: Labofina SA
Priority date: 1979-03-20
Filing date: 1980-02-11
Publication date: 1980-12-10
Also published as: DE3009065C2; FR2451928B1; JPS55125140A; IT1140778B; NO800768L; NL8001248A; CA1145083A; NO162077B; NO162077C; GB2048276B; SU1097200A3; NL190163B; JPH0255454B2; BE882241A; SE8002057L; FR2451928A1; IT8020521A0; NL190163C; CS226409B2; DE3009065A1

Abstract

A self-extinguishing polystyrenic composition comprising a polystyrenic resin, a fire-retardant amount of a halogenated organic fire-retardant agent and a nitrogen-containing organic compound selected from amines, amides and ammonium compounds containing from 20 to 40 carbon atoms and their mixtures, the nitrogen-containing compound being used in an amount of from 0.5 to 50% based on the weight of fire-retardant agent.

Description

SPECIFICATION Fire-retardant Polystyrenic Compositions This invention related to fire-retardant polystyrenic compositions.

For many uses, fire-retardant agents must be incorporated into polystyrenic resins, such as polystyrene, styrene-acrylonitrile copolymers (known as SAN resins), acrylonitrile-butadiene-styrene copolymers (known as ABS resins), high impact polystyrenes and the like, to impart fire-resistance to such resins. Organic compounds containing bromine and/or chlorine are frequently employed as fireretardant agents. However, large amounts of fire-retardant agents are often required to obtain polystyrenic compositions which fulfil specifications relating to flame propagation; and these large amounts are detrimental for other properties of the polystyrenic compositions, such as tensile strength and thermal stability.

With a view to decreasing the amount of fire-retardant agent which must be added to such resins, the synergistic action of some additives (or synergistic compounds) which, when used alone, do not act as fire-retardant agents, has been contemplated. Organic peroxides have been suggested as synergistic compounds, but they have several drawbacks, more particularly with respect to toxicity and stability.

U.S. Patent No. 4,092, 281 discloses certain nitrogen-containing synergistic compounds for use in fire-retardant polystyrenic compositions. The present invention represents an improvement thereover.

According to one aspect of the present invention, there is provided a polystyrenic composition comprising a polystyrenic polymer, a haiogenated organic fire-retardant agent and a nitrogencontaining organic compound selected from amines, amides and ammonium compounds containing from 20 to 40 carbon atoms and their mixtures, said nitrogen-containing organic compound being used in an amount of from 0.5 to 50% based on the weight of the fire-retardant agent.

According to another aspect of the present invention there is provided a fire-retardant composition for use in combination with polystyrenic resins, said composition containing a halogenated organic fire-retardant agent and a nitrogen-containing organic compound as defined above.

In this specification, the term "polystyrenic resins" includes 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-impact polystyrenes containing an elastomer, such as rubber, in an amount which may reach as much as about 15% by weight. The invention applies also to expanded polystyrene, which may be produced either by molding expandable beads of polystyrene or by extruding mixtures of polystyrene and a blowing agent.

It has been found that expanded polystyrene produced by extruding polystyrenic resins in the presence of a blowing agent together with a nitrogen-containing compound of the type used in the present invention have cells the average size of which is substantially lower than those of similar expanded polystyrenes produced in the absence of such- a nitrogen-containing compound. For instance, the size of the cells of an expanded polystyrene produced in the presence of an ammonium compound of the present invention is from 80 to 100 microns, whereas the size of the cells is about 200 microns when the ammonium compound is not used. As a result, the expanded polystyrenes prepared from the compositions of the present invention have a lower density and improved self-extinguishing properties, and they are therefore particularly advantageous for many uses.

The flame-retardant agent 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 polystyrenic composition is at least about 0.2%. Contents higher than about 15% do not bring any advantage. More generally, the halogen-content in the final polystyrenic composition is from 0.5 to 10% by weight. This amount depends mainly on the kind of halogenated fire-retardant agent; brominated compounds are generally more active than the corresponding chlorinated compounds and they may therefore be used in lower amounts. These agents and their use are well known in the art.Typical halogenated fire-retardant agents are acetylene tetrabromide, dibromotetrachloroethane, tetrachloroethane, pentachloroethane, hexachloro- or hexabromobenzene, tetrabromobutane, polyhalobiphenyls, poly halobiphenylethers, perhalopentacyclododecanes, pentabromomonochlorocyclohexane, solid and liquid chlorinated paraffins and the like and mixtures thereof.

The nitrogen-containing organic compounds of this invention are synergistic compounds for the halogenated organic compounds which are used as fire-retardant agents for polystyrenic resins. these nitrogen-containing compounds are amines, amides or ammonium compounds containing from 20 to 40 carbon atoms and preferably from 26 to 40 carbon atoms. They are very active synergistic compounds and they are generally used in an amount which may be from 0.5% to 50%, based on the weight of fire-retardant agent. This amount depends on the type of fire-retardant agent and on the type of nitrogen containing compound. Generally, the synergistic compound may be used in an amount of from 0.02 to 2% by weight of polystyrenic resin.

The choice of the nitrogen-containing organic compound depends mainly on its price and its a) secondary and tertiary amines having the general formula N(R1) (R2) (R3), wherein R, is H or an alkyl radical containing from 9 to 18 carbon atoms and R2 and R3, which may or may not be the same, are each an alkyl radical containing from 9 to 18 carbon atoms; b) fatty acid amides containing more than 25 carbon atoms, more particularly, alkylene-bis amides, preferably lower alkylene-bis-amides and most preferably alkylene-bis-amides wherein the alkylene group contains 1 to 5 carbon atoms, such as ethylene-bis-stearylamide and similar; c) ammonium compounds, such as cl) alkylpyridinium bromides of the formula

wherein R4 is an alkyl radical containing at least 1 5 carbon atoms, or coil) ammonium compounds of the general formula

wherein X is Cl, Br or alkylsulfate and the radicals R5 to R8 are H or radicals containing from 1 to 18 carbon atoms, the total of the carbon atoms of the ammonium compound being at least 20.By way of example, there may be mentioned the following preferred ammonium compounds wherein: (1) R5 and R7 are methyl radicals; Re is an alkyl radical containing at least 9 carbon atoms, such as lauryl or stearyl; R8 is the same as Re or is a benzyl radical; and X is Cl or Br; (2) R5 and R7 are methyl radicals; R6 is a dialkyl phenoxyethoxyethyl radical, preferably diisobutyl-phenoxyethoxyethyl; Ra is a benzyl radical; and X is CI or Br; (3) R5 and R7 are methyl radicals; Re is an alkyl radical containing at least 4 carbon atoms, such as butyl or hexyl; Re is H; and X is an alkylsulfate group wherein the alkyl radical contains at least 12 carbon atoms; such as lauryl or stearyl.

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

Some fire-retardant agents, more particularly the agents which possess a high thermal stability, are advantageously used in admixture with antimony oxide. It has been found that the amount of antimony oxide to be added may be decreased by about 50% below that conventionally employed without detrimental effect on the fire-retardant properties or on the thermal stability of the final polystyrenic composition when a nitrogen-containing compound is incorporated as a synergistic compound into the composition. The amount of antimony oxide, when used, does not generally exceed 7% by weight of polystyrenic resin. This amount depends on the kind and amount of fire-retardant agent, and it is generally from 2 to 5%. With other fire-retardant agents, more particularly with halogenated aliphatic compounds, the use of antimony oxide is not required.

The following Examples illustrate the present invention.

The self-extinguishing properties of the polystyrenic compositions are determined with the use of specimens measuring 1 2.70x 1 .27x0.32 cm, according to the following test: Each specimen is hung, the larger dimension being vertical and the distance between the lower end of the specimen and the upper end of the burner being 0.95 cm. The burner is lighted and the flame has a height of 1.9 cm. Air is premixed with the gas in order to avoid any yellow tip at the top of the flame. This flame is disposed under the lower end of the specimen for a period of 10 seconds. The burner is then removed and the flaming combustion time is measured. Immediately after extinction, the flame is again disposed under the specimen for a period of 10 seconds. The burner is then removed, and the flaming combustion time is again measured. The data given in the Examples are the average of 20 successive tests (10 specimens and 2 determinations for each specimen). In the case of foamed polystyrene, the same procedure is used, except the flame is disposed under the specimen only once and for a period of 3 seconds.

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

Example 1 compositions are prepared from crystal polystyrene, 0.75% pentabromomonochlorocyclohexane, 0.05% di-tert-butylhydroxytoluene (BHT), 0.035% zinc stearate and 0.20 of the following synergistic compounds.

The self-extinguishing times are as follows: Flaming combustion time Synergistic compound (in seconds) Stearyl-dimethyl-benzyl ammonium chloride 0.42 Distearyl dimethyl ammonium chloride 0.44 Dilauryl dimethyl ammonium bromide 0.23 Diisobutyl-phenoxy-ethoxy-ethyl-dimethylbenzyl ammonium chloride monohydrate 0.51 Cetylpyridinium bromide 2.07 ethylene-bis-stearylamide 0.87 Distearylamine 0.54 Trilaurylamine 0.80 Hexyi-dimethyl-ammoniu m stearyl-sulfate 0.44 A similar composition but without any synergistic compound has a flaming combustion time of 11.71 seconds.

Example 2A Compositions are prepared from crystal polystyrene, 0.05% BHT, 0.035% zinc stearate, and a fireretardant agent (for the type and amount, see the following table), dilauryl-dimethyl-ammonium chloride as the synergistic compound (for the amount, see the following table):: Flaming Amount of combustion Fire-retardant Amount of synergistic time (in agent Sub203 {%) cmpd(%) seconds) Acetylene tetrabromide (0.75%) 0 0.020 0.49 Dibromotetrachloroethane (0.75%) 0 0.20 1.24 Pentachloroethane (0.75%) 0 0.10 9.17 Tetrabromobutene (0.75%) 0 0.05 1.58 Example 2B Compositions are prepared from high impact polystyrene (containing 6% rubber), 0.05% BHT, 0.035% zinc stearate, and a fire-retardant agent (for the type and amount, see the following table), dilauryl-dimethyl-ammonium chloride as the synergistic compound (for the amount, see the following table), and antimony oxide Sb2O3 (for the amount, see the following table):: Flaming Amount of combustion Amount of synergistic time (in Fire-retardant agent Sb2O3 (%) cmpd. {%) seconds) Hexabromobenzene (10%) 3 0.05 1.24 Polybromo biphenylether (10%) 3 2.00 0.97 Perchloropentacyclododecane (15%) 3 2.00 1.12 Perchioropentacyclododecane (109/0) 3 2.00 3.17 Example 3 Polystyrene is prepared by suspension polymerization of styrene in the presence of pentabromomonochlorocyclohexane (1%) and distearyl-dimethyl-ammonium chloride (0.15%). The beads of polystyrene are washed with water and then kept under vacuum at 75CC for one night.

The flaming combustion time of specimens produced from this polystyrene is 0.46 seconds.

Example 4 A composition is prepared from high-impact polystyrene (containing 6% rubber), 0.05% BHT, decabromo biphenyl, 3% Sub203 and 0.5% trilaurylamine.

The flaming combustion time is 1.10 seconds.

A similar composition but without the fatty amine has a flaming combustion time of 2.18 seconds.

availability. Particularly advantageous nitrogen-containing compounds are: Example 5 Specimens of expanded polystyrene are prepared by injection molding expandable beads of polystyrene (containing pentane as the blowing agent). Pentabromomonochlorocyclohexane (1.5%) and dilauryl-dimethyl ammonium chloride (0.2%) are added to these beads.

The flaming combustion time is 0.70 seconds (as compared with 3.21 seconds in the absence of the ammonium compound).

Example 6 Specimens of expanded polystyrene are prepared by extruding polystyrene in the presence of a blowing mixture (containing equal weights of CF2CI2 and CFCI3),3% pentabromomonochlorocyclohexane and 0.1% distearyldimethyl ammonium chloride.

The flaming combustion time is 1.10 seconds. The cells of the expanded polystyrene have an average size of 80 microns, and the density of the final product is 35 kg/m3.

A similar product but prepared without the ammonium compound has the following properties: flaming combustion time 4.38 seconds cell size 200 microns density 39 kg/m3.

Example 7 A composition is prepared from crystal polystyrene, 5% chlorinated paraffin (average of 25 carbon atoms and chlorine-content=70%), 0.1% BHT, 0.035% zinc stearate and 0.2% distearyldimethyl-ammonium chloride.

The flaming combustion time is 10.6 seconds.

A similar composition but without ammonium compound has a flaming combustion time higher than 60 seconds.

Example 8 A composition is prepared from ABS resin (containing 7% butadiene and 17% acrylonitrile), 12% decabromodiphenyloxide, 5% Sb203 and 2% distearyl-dimethyl-ammonium chloride.

The flaming combustion time is 1.1 7 seconds.

A similar composition but without ammonium compound has a flaming combustion time of 3.48 seconds.

Claims

1. A self-extinguishing polystyrenic composition comprising a polystyrenic resin, a fire-retardant amount of a halogenated organic fire-retardant agent, and a nitrogen-containing organic compound which contains from 20 to 40 carbon atoms and which is selected from a) a secondary or tertiary amine having at least one alkyl radical containing from 9 to 18 carbon atoms; b) a fatty acid amide containing at least 26 carbon atoms; and c) an ammonium compound selected from cl) an alkylpyridinium bromide of the formula

wherein R4 is an alkyl radical containing at least 1 5 carbon atoms, or coil) an ammonium compound of the formula

wherein X is Cl, Br or alkyl-sulfate and the radicals R5 to Ra are H or a radical containing from 1 to 18 carbon atoms; or d) a mixture thereof, the nitrogen-containing compound being present in an amount of from 0.5 to 50% based on the weight of the fire-retardant agent.

2. A composition according to Claim 1, wherein the nitrogen-containing compound is used in an amount of from 0.01 to 5% by weight of the polystyrenic resin.

3. A composition according to Claim 2, wherein the amount of nitrogen-containing compound is from 0.02 to 2% by weight of the polystyrenic resin.

4. A composition according to Claim 1, 2 or 3, further comprising antimony oxide in an amount which does not exceed about 7% by weight of the polystyrenic resin.

5. A composition according to Claim 4, wherein the amount of antimony oxide is from 2 to 5% by weight of the polystyrenic resin.

6. A composition according to any one of the preceding claims, wherein the polystyrenic resin comprises homopolystyrene or a styrene copolymer containing a major amount of styrene.

7. A composition according to Claim 6, wherein the styrene copolymer comprises an ABS copolymer, a SAN copolymer or a rubber-modified polystyrene.

8. A composition according to any one of the preceding claims, wherein the polystyrenic resin comprises an expanded resin.

9. A composition according to any one of the preceding claims, wherein the fire-retardant agent is acetylene tetrabromide, dibromotetrachloroethane, tetrachloroethane, pentachloroethane, hexachloro- or hexabromobenzene, tetrabromobutane, polyhalobiphenyls, polyhalobiphenylethers, perhalopentacyclododecanes, pentabromomonochlorocyclohexane, a chlorinated paraffin or a mixture thereof.

10. A composition according to any one of the preceding claims, wherein the nitrogen-containing organic compound comprises a secondary or tertiary amine having the formula N (R,) (R2) (R3), wherein R1 is H or an alkyl radical containing from 9 to 18 carbon atoms and R2 and R3, which may or may not be the same, are each an alkyl radical containing from 9 to 1 8 carbon atoms.

11. A composition according to any one of Claims 1 to 9, wherein the nitrogen-containing organic compound comprises an alkylene-bis-fatty acid amide.

12. A composition according to any one of Claims 1 to 9, wherein the nitrogen-containing organic compound comprises an ammonium compound of the formula

wherein either (ii) R5 and R7 are methyl radicals, Re is a dialkyl-phenoxy-ethoxyethyl radical; Ra is a benzyl radical; and X is CI or Br; or R is an a (iii) R5 and R7 are methyl radicals, Rff is an alkyl radical containing at least 4 carbon atoms, Re is H and X is an alkyl sulfate group wherein the alkyl radical contains at least 12 carbon atoms.

13. A composition according to Claim 12, wherein Re in compound (i) is lauryl or stearyl.

14. A composition according to Claim 12, wherein Re in compound (iii) is butyl or hexyl and the alkyl radical of the alkylsulfate group is lauryl or stearyl.

1 5. A composition according to any one of Claims 1 to 9, wherein the nitrogen-containing compound comprises stearyl-dimethylbenzyl ammonium chloride, distearyl dimethyl ammonium chloride, dilauryl dimethyl ammonium bromide, diisobutylphenoxy-ethoxy-ethyl-dimethylbenzyl ammonium chloride monohydrate, cetylpyridinium bromide, ethylene-bis-stearyl-amide, distearylamine, trilaurylamine, hexyl-dimethyl-ammonium stearyl-sulfate, or dilauryl-dimethylammonium chloride.

1 6. A self-extinguishing polystyrenic composition according to Claim 1 substantially as described in any one of the foregoing Examples 1 to 8.

1 7. A fire-retardant composition for use in combination with polystyrene resins, comprising a halogenated organic fire-retardant agent and a nitrogen-containing organic compound which contains from 20 to 40 carbon atoms and which is selected from a) a secondary or tertiary amine having at least one alkyl radical containing from 9 to 1 8 carbon atoms; b) a fatty acid amide containing at least 26 carbon atoms; and c) an ammonium compound selected from cl) an alkylpyridinium bromide of the formula

wherein R4 is an alkyl radical containing at least 1 5 carbon atoms, or coil) an ammonium compound of the formula:

wherein X is Cl, Br or alkyl-sulfate and the radicals R5 to Ra are H or a radical containing from 1 to 1 8 carbon atoms, or d) a mixture thereof, the nitrogen-containing compound being present in an amount of from 0.5 to 50% based on the weight of the fire-retardant agent.

18. A composition according to Claim 17, wherein the fire-retardant agent is acetylene tetrabromide, dibromotetrachloroethane, tetrachloroethane, pentachloroethane, hexachloro- or hexabromobenzene, tetrabromobutane, polyhalobiphenyls, polyhalobiphenylethers, perhalopentacyclododecanes, pentabromomonochlorocyclohexane, a chlorinated paraffin or a mixture thereof.

1 9. A composition according to Claim 1 7 or 18, wherein the nitrogen-containing organic compound comprises a secondary or tertiary amine having th formula N(Rt) (R2) (R3), wherein R1 is H or an alkyl radical containing from 9 to 18 carbon atoms and R2 and R3, which may or may not be the same, are each an alkyl radical containing from 9 to 1 8 carbon atoms.

20. A composition according to Claim 17 or 18, wherein the nitrogen-containing organic compound comprises an alkylene-bis-fatty acid amide.

21. A composition according to Claim 17 or 18, wherein the nitrogen-containing organic compound comprises an ammonium compound of the formula

wherein either (i) R5 and R7 are methyl radicals, Re is an alkyl radical containing at least 9 carbon atoms, Ra is the same as Re or is a benzyl radical; and X is Cl or Br; or (ii) Ra and R are methyl radicals, Re is a dialkyl-phenoxy-ethoxyethyl radical; Ra is a benzyl radical; and X is Cl or Br; or (iii) R5 and R7 are methyl radicals, Re is an alkyl radical containing at least 4 carbon atoms, R8 is H and X is an alkylsulfate group wherein the alkyl radical contains at least 12 carbon atoms.

22. A composition according to Claim 21, wherein Re in compound (i) is lauryl or stearyl.

23. A composition according to Claim 21, wherein Re in compound (iii) is butyl or hexyl and the alkyl radical of the alkyl-sulfate group is lauryl or stearyl.

24. a composition according to Claim 17 or 18, wherein the nitrogen-containing compound comprises stearyl-dimethyl-benzyl ammonium chloride, distearyl dimethyl ammonium chloride, dilauryl dimethyl ammonium bromide, diisobutylphenoxy-ethoxy-ethyl-dimethylbenzyl ammonium chloride monohydrate, cetylpyridinium bromide, ethylene-bis-stearyl-amide, distearylamine, trilaurylamine, hexyl-dimethyl ammonium stearyl-sulfate, or dilauryl-dimethyl-ammonium chloride.

25. A fire-retardant composition according to Claim 1 7 substantially as hereinbefore described.