Flame retardant polymer compositions The present invention relates to polymers containing a flame retardant additive.
Accordingly, the present invention provides a polymer and a flame retardant amount of a triaryl phosphate or mixture or triaryl phosphates of the general formula
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wherein R represents a C1 C9 alkyl group, a C6 C9 cycloalkyl group or a C7-C9 aralkyl group, n is 0-3, preferably 0-2 and x has an average value greater than 0 but less than 3.
When a single triaryl phosphate is used x has a value of 1 or 2. When a mixture of triaryl phosphates is used the value of x in any single compound may be 0, 1, 2 or 3 giving an average value above 0 but less than 3, preferably an average value of 0.5-2.5.
Examples of R are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl pentyl, hexyl, heptyl, octyl, nonyl, cyclohexyl, benzyl, phenylethyl and phenylpropyl.
Preferably R represents an alkyl group with 1 to 4 carbon atoms.
Examples of suitable phosphates are mono (2,4,6-tribromophenyl) diphenyl phosphate; bis (2,4,6tribromophenyl) monophenyl phosphate; mono (2,4,6-tribromophenyl) bis (p-cresyl) phosphate; bis (2,4,6-tribromophenyl) mono (2,6-xylyl) phosphate; mono (2,4,6-tribromophenyl) bis (m-ethyl phenyl) phosphate; mono (2,4,6-tribromophenyl) bis (p-tert-butylphenyl) phosphate; bis (2,4,6-tribromophenyl) mono (p-octylphenyl) phosphate; bis (2,4,6-tribromophenyl) mono (p-nonylphenyl) phosphate; mono (2,4,6-tribromophenyl) bis (o-cyclohexylphenyl) phosphate; bis (2,4,6-tribromophenyl) mono (p-benzylphenyl) phosphate; bis (2,4,6-tribromophenyl) mono (p-phenylethylphenyl) phosphate; mono (2,4,6-tribromophenyl) bis (isopropylated phenyl) phosphate; and bis (2,4,6-tribromophenyl) mono (isopropylated phenyl) phosphate.
The term "isopropylated phenyl" indicates that the phosphate is derived from a mixture of phenols obtained by isopropylating phenol in a Friedel Crafts reaction, for example, by the method described in British Patent Specification No. 1146173. Such a mixture normally contains unreacted phenol, mono isopropyl phenols (mainly the ortho and para isomers), di-isopropyl phenols and some tri-isopropyl phenols.
The phosphates may be made by known procedures, for example, by phosphorylating a mixture of tribromophenol and the appropriate alkyl phenol or mixture of alkyl phenols in a one or two stage process or by reacting tribromophenol with an aryl phosphorodichloridate or di-aryl phosphorochloridate or by reacting a tribromophenyl phosphorochloridate with the appropriate alkyl phenol. The usual phosphorylating agents, e.g. phosphorus oxychloride, phosphorus pentachloride may be employed. The reaction may be performed in the presence of a catalyst, e.g. aluminium chloride, magnesium chloride or a catalytic quantity of an amine or amide. Alternatively, molar quantities of an inorganic or organic base, such as sodium hydroxide, pyridine or triethylamine may be used. The reaction may be performed in the absence of solvent or with an organic solvent such as diethyl ether, toluene, xylene.
Some of the phosphates are new compounds. The present invention accordingly provides triaryl phosphates of the general formula
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wherein x is as defined and OZ represents a mixture of radicals derived from phenol alkylated with from 5 to 65%, preferably 10 to 40% by weight of isopropyl radicals or t-butyl radicals, based on the weight of phenol.
It should be understood that OZ represents a mixture of radicals, including, in the case of isopropylated phenol compounds, those derived from phenol, o-isopropyl phenol, p-isopropyl phenol, misopropyl phenol, 2,4-diisopropyl phenol, 2,6-diisopropyl phenol, 2,4,6-triisopropyl phenol and other diand tri-isopropyl phenols. The amount of each isopropyl phenol compound in the mixture varies depending on the conditions used in the alkylation procedure, e.g. catalyst and reaction temperature.
A typical mixture of phenols obtained by isopropylating phenol with propylene under Friedel-Crafts conditions and which may be used to make triaryl phosphates of the present invention comprises about 30% phenol, about 40% o-isopropyl phenol, about 10% m/p-isopropyl phenol, about 15% di-isopropyl phenols and about 5% tri-isopropyl phenols.
In the case of t-butylated phenol compounds OZ represents a mixture of radicals including those derived from phenol, p-t-butyl phenol, m-t-butyl phenol and di-t-butyl phenols, in varying proportions depending on the alkylation procedure.
The polymers to which the phosphates may be added in order to improve their flame retardant include 1. Polymers of monolefines and diolefines, for example polyethylene, polypropylene, polyisobutylene, polybutene-1, polymethylpentene-1, polyisoprene or polybutadiene, as well as polymers of cycloolefines, for instance of cyclopentene or norbornene.
2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyethylene or with polyisobutylene.
3. Copolymers of monoolefines and diolefines with each other or with other vinyl monomers, such as, for example, ethylene/propylene, propylene/butene-1, propylene/isobutylene, ethylene/butene-1, propylene/butadiene, isobutylene/isoprene, ethylene/ethyl acrylate, ethylene/alkyl methacrylates, ethylene/vinyl acetate or ethylene/acrylic acid copolymers and their salts (ionomers) and terpolymers of ethylene with propylene and a diene, such as hexadiene, dicyclopentadiene or ethylidene-norbornene.
5. Random copolymers of styrene or a-methylstyrene with dienes or acrylic derivatives, such as, for example, styrene/butadiene, styrene/acrylonitrile, styrene/alkyl methacrylates, styrene/acrylonitrile/methyl acrylate; mixtures of high impact strength from styrene copolymers and another polymer, such as, for example, from a polyacrylate, a diene polymer or an ethylene/propylene/diene terpolymer; and block copolymers of styrene, such as, for example, styrene/butadiene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/styrene.
6. Graft copolymers of styrene, such as, for example styrene on polybutadiene, styrene and acrylonitrile on polybutadiene, styrene and alkyl acrylates or methacrylates on polybutadiene, styrene and acrylonitrile on ethylene/propylene/diene terpolymers, styrene and acrylonitrile on polyacrylates on polymethacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, as well as mixtures thereof with the copolymers listed under 5), for instance the copolymer mixtures known as ABS-, MBS-, ASA- or AES-polymers.
7. Halogen-containing polymers, such as polychloroprene, chlorinated rubbers, chlorinated or sulfochlorinated polyethylene, polymers from halogen-containing vinyl compounds, as for example, polyvinyl chloride, polyvinylidene chloride, as well as copolymers thereof, as for example, vinyl chloride/vinylidene chloride, vinyl chloride/vinyl acetate or vinylidene chloride/vinyl acetate copolymers.
8. Polymers which are derived from derivatives of alpha ,beta -unsaturated acids, such as polyacrylates and polymethacrylates, polyacrylamides and polyacrylonitrile.
9. Copolymers from the monomers mentioned under 8) with each other or with others unsaturated monomers, such as, for instance, acrylonitrile/butadiene, acrylonitrile/alkyl acrylate or acrylonitrile/vinyl chloride copolymers or acrylonitrile/alkyl methacrylate/butadiene terpolymers.
10. Polymers which are derived from unsaturated alcohols and amines, or acyl derivatives thereof or acetals thereof, such as polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyallyl phthalate or polyallyl-melamine.
11. Polyacetals, such as polyoxymethylene and those polyoxymethylenes which contain ethylene oxide as a comonomer.
12. Polyphenylene oxides and sulfides.
13. Polyurethanes which are derived from polyethers, polyesters or polybutadiene with terminal hydroxyl groups on the one side and aliphatic or aromatic polyisocyanates on the other side, as well as precursors thereof.
14. Polyamides and copolyamides which are derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 11, polyamide 12, poly-2,4,4-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide, as well as copolymers thereof with polyethers, such as for instance, with polyethylene glycol, polypropylene glycol or polytetramethylene glycols.
15. Polyureas, polyimides and polyamide-imides.
16. Polyesters which are derived from dicarboxylic acids and dialcohols and/or from hydroxycarboxylic acids or the corresponding lactones, such as polyethylene terephthalate, polybutylene
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block-copolyether-esters derived from polyethers having hydroxyl end groups.
18. Polysulfones and polyethersulfones.
19. Crosslinked polymers which are derived from aldehydes on the one hand and phenols, cresols, ureas and melamines on the other hand, such as phenol/formaldehyde resins, cresol/formaldehyde resins, phenol/cresol/formaldehyde resins, urea/formaldehyde resins and melamine/formaldehyde resins.
20. Drying and non-drying alkyd resins.
21. Unsaturated polyester resins which are derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols and vinyl compounds as crosslinking agents, and also halogen-containing modifications thereof of low inflammability.
22. Thermosetting acrylic resins, derived from substituted acrylic esters, such as epoxy-acrylates, urethane-acrylates or polyester-acrylates.
23. Alkyd resins, polyester resins or acrylate resins in admixture with melamine resins, urea resins, polyisocyanates or epoxide resins as crosslinking agents.
24. Crosslinked epoxide resins which are derived from polyepoxides, for example from bis-glycidyl ethers or from cycloaliphatic diepoxides.
25. Natural polymers, such as cellulose, rubber, gelatine and derivatives thereof which are chemically modified in a polymer-homologous manner,-such as cellulose acetates, cellulose propionates and cellulose butyrates, or the cellulose ethers, such as methylcellulose.
26. Naturally occurring and synthetic organic materials which are pure monomeric compounds or mixtures of such compounds, for example mineral oils, animal and vegetable fats, oils and waxes, or oils. fats and waxes based on synthetic esters (e.g. phthalates, adipates, phosphates trimellitates) and also mixtures of synthetic esters with mineral oils in any weight ratios, which materials may be used as plasticiser for polymers or as textile spinning oils, as well as aqueous emulsions of such materials.
27. Aqueous emulsions of natural or synthetic rubber, e.g. natural latex or latices of carboxylated styrene/butadiene copolymers.
The phosphates may be added to the polymer in amounts of 0.1 to 100 parts by weight per hundred parts by weight of polymer (phr) preferably 1 to 40 phr and, more preferably, 2 to 30 phr.
In some polymers they give improved flame retardance over a mixture of bromine containing and phosphorus containing compounds used in admixture and give at least as good results in other polymers.
The compositions of the invention may also contain other ingredients normally added to plastics such as heat stabilisers, light stabilisers, UV absorbers, antioxidants, fillers, pigments, lubricants, additives to improve mold release, fungicides, blowing agents, optical brightening agents, other flame retardant additives, processing aids and smoke suppressants.
The invention is illustrated by the following Examples.
EXAMPLE 1 Preparation of mono (tribromophenyl) bis (isopropylphenyl) phosphate 830 parts of 2,4,6-tribromophenol, 384 parts of phosphorus oxychloride and 7.5 parts of aluminium chloride catalyst are heated with stirring to 130[deg]C. over 3 hours followed by a further 1 hour heating at 130[deg]C. 726 parts of a mixture of phenol and isopropylated phenols (containing approximately 30% phenol, 30% ortho isopropyl phenol, 10% meta/para isopropyl phenol, 20% diisopropyl phenols and 5% tri-isopropyl phenols prepared by reacting phenol with 0.725 moles propylene/mole phenol) are then added over 1 hour at 130[deg]C. The temperature is raised to 220[deg]C. over 1 hour and heating continued for 3 hours at 220[deg]C. After a further 3 hours heating at 220[deg]C. under water pump vacuum the reaction mixture is cooled to room temperature and dissolved in 1500 parts of toluene.The toluene solution is then washed with 2 x 1,000 parts 5% sodium hydroxide solution and 4 x 1,000 parts of water. The toluene solvent is then removed by evaporating to dryness on a rotary evaporator at 100[deg]C. under water pump vacuum. This yields 1175 parts of a viscous brown liquid containing 5.4% phosphorus and 35.0% bromine. P NMR shows the product to be a mixture of tri-aryl phosphates- mainly mono (tribromophenyl) bis (isopropylphenyl) phosphates.
EXAMPLE 2 Bis (tribromophenyl) isopropylphenyl phosphate 218.5 parts of 2,4,6-tribromophenyl, 50.7 parts of phosphorus oxychloride and 1.5 parts of aluminium chloride catalyst are heated, with stirring, to 200[deg]C. over 3 hours followed by a further 2 hours heating at 200[deg]C. The reaction mixture is cooled to 150[deg]C. and 48.6 parts of a mixture of phenol and isopropylated phenols as described in Example 1 are then added over 30 minutes at 150[deg]C. The temperature is raised to 220[deg]C. over 1 hour and heating continued for 6 hours at 220[deg]C. After a further 3 hours heating at 220[deg]C. underwater pump vacuum the reaction mixture is cooled to room temperature and dissolved in 250 parts toluene. The toluene solution is then washed with 2 x 250 parts 5% sodium hydroxide solution and 4 x 250 parts water.The toluene solvent is then removed by evaporating to dryness on a rotary evaporator at 100[deg]C. under water pump vacuum. This yields 168 parts of a very viscous brown liquid containing 3.9% phosphorus and 43% bromine. P NMR shows the product to be a mixture of tri-aryl phosphates - mainly bis (tribromophenyl) isopropylphenyl phosphates.
EXAMPLE 3 Mono (tribromophenyl) diphenyl phosphate 66.2 parts 2,4,6-tribromophenol, 30 parts triethylamine and 350 parts toluene (dried over sodium) are mixed and cooled to 5[deg]C. 53.7 parts diphenyl phosphorochloridate are then added over 30 minutes at 0[deg]-10[deg]C. The reaction mixture is allowed to warm to room temperature and then heated to reflux and stirred at reflux for 5 hours. The mixture is then cooled, triethylamine hydrochloride filtered off and the toluene solution washed with 2 x 250 parts 5% sodium hydroxide solution and 4 x 250 parts water. The toluene solvent is then removed by evaporating to dryness on a rotary evaporator at 100[deg]C. under water pump vacuum. This yields 72.4 parts of a viscous liquid containing 5.4% phosphorus and 41 % bromine. P NMR shows the product to be essentially pure mono (tribromophenyl) diphenyl phosphate.
EXAMPLE 4 Bis (tribromophenyl) phenyl phosphate 66.2 parts 2,4,6-tribromophenol, 30 parts triethylamine and 250 parts toluene (dried over sodium) are mixed and cooled to 5[deg]C. 21.1 parts of phenyl phosphorodichloridate are then added over 1 hour at 0[deg]-10[deg]C. The reaction mixture is allowed to warm to room temperature and then heated to reflux and stirred at reflux for 5 hours. The'mixture is then cooled, triethylamine hydrochloride filtered off and the toluene solution washed with 2 x 250 parts 5% sodium hydroxide solution and 4 x 250 parts water. The toluene solvent is then removed by evaporating to dryness on a rotary evaporator at 100[deg]C. under water pump vacuum. This yields a solid product which is recrystallised from aqueous ethanol to give 24.4 parts of a white solid containing 3.8% phosphorus and 58% bromine.P NMR shows the product to be essentially pure bis (tribromophenyl) phenyl phosphate. The product has a melting point of 132.-135[deg]C.
EXAMPLE 5 Phenol-formaldehyde/paper laminates are prepared containing the flame retardant compounds given in the Table 1 below. The oxygen index (O.I) is measured according to ASTM method 2863. The burning of the sample is measured according to the "Test for Flammability of Plastic Materials - UL 94", September 17, 1973.
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It can be seen that the products of Example 1 and Example 2 enhance the flame retardance of the laminate as evidenced by the higher oxygen index and the improved rating in the UL.94 test.
EXAMPLE 6 Samples of an unsaturated polyester resin containing methyl ethyl ketone peroxide (MEKP) catalyst and a cobalt accelerator were produced with the formulation shown in Table 2 (in parts by weight), and giving the results indicated.
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The results show that the compositions of the invention have flame retardant properties as good as or better than those containing other flame retardant additives.
EXAMPLE 7 Samples of a polyurethane were produced with the formulations shown in Table 3 (in parts by weight) and giving the results shown.
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It can be seen that the products of Examples 1 and 2 are as good as or better than tris (2,3dibromopropyl) phosphate.