Preparation of bromine-containing aromatic compounds and their application as flame retardants

Abstract

The invention relates to compounds of the formula Ar(CH.sub.2C.sub.6Br.sub.5).sub.y, wherein Ar indicates a structure comprising one or more six-membered aromatic ring(s) and CH.sub.2C.sub.6Br.sub.5 indicates a pentabromobenzyl group, characterized in that at least one carbon atom of said six-membered aromatic ring(s) is bonded to the benzylic carbon of said CH.sub.2C.sub.6Br.sub.5 group, wherein y, which indicates the number of the CH.sub.2C.sub.6Br.sub.5 groups in said compound, is not less than 1. Processes for preparing the compounds and their use as flame retardants are also disclosed.

Claims

1. A process for preparing a compound of the formula Ar(CH.sub.2C.sub.6Br.sub.5).sub.y, wherein Ar indicates a structure comprising one or more six-membered aromatic ring(s), CH.sub.2C.sub.6Br.sub.5 is the pentabromobenzyl group and y indicates the number of the CH.sub.2C.sub.6Br.sub.5 groups in the compound, said process comprises a Friedel-Crafts alkylation reaction of pentabromobenzyl halide with a reactant, wherein said reactant contains one or more six-membered aromatic rings, in the presence of a Friedel-Crafts catalyst, to form said Ar(CH.sub.2C.sub.6Br.sub.5).sub.y compound having not less than two CH.sub.2C.sub.6Br.sub.5 groups bonded to each said one or more six-membered aromatic rings, such that the bond is between a carbon atom of the six-membered aromatic ring and the benzylic carbon of the pentabromobenzyl group.

2. A process according to claim 1, wherein three CH.sub.2C.sub.6Br.sub.5 groups are attached to each six-membered aromatic rings present in the reactant.

3. A process according to claim 1, wherein the Friedel-Crafts catalyst is selected from the group consisting of AlCl.sub.3, AlBr.sub.3, GaCl.sub.3, FeCl.sub.3, SnCl.sub.4, SbCl.sub.3, ZnCl.sub.2, CuCl.sub.2 and HF.

4. A process according to claim 1, wherein the reactant is a compound of Formula (II): ##STR00006## wherein R is H or a linear or branched aliphatic chain, m is 0 or 1, k is an integer from 1 to 3, X=null, an alkylene group containing 1 to 10 carbon atoms, O and S.

5. A process according to claim 4, wherein the reactant is selected from the group consisting of: Toluene, wherein in Formula II m=0, R=CH.sub.3, k=1; Xylene, wherein in Formula II m=0, R=CH.sub.3, k=2; Ethylbenzene, wherein in Formula II m=0, R=C.sub.2H.sub.5, k=1; Diphenyl ether, wherein in Formula II m=1, R=H, X=O; Diphenylmethane, wherein in Formula II m=1, R=H, X=CH.sub.2; and Diphenylethane, wherein in Formula II m=1, R=H, X=(CH.sub.2).sub.2.

6. A process according to claim 5, comprising a Friedel-Crafts alkylation reaction of pentabromobenzyl bromide with a reactant selected from the group consisting of toluene, xylene, ethylbenzene, diphenyl ether, diphenylmethane and diphenylethane in the presence of aluminum chloride, wherein the molar ratio between said pentabromobenzyl bromide and said reactant is at least equal to twice the number of the six-membered aromatic rings of said reactant.

7. A process according to claim 1, wherein the Friedel-Crafts alkylation reaction takes place in a solvent which is halogenated aliphatic hydrocarbon.

8. A product mixture consisting of homologous series of the formula Ar(CH.sub.2C.sub.6Br.sub.5).sub.y, where Ar indicates a structure comprising one or more six-membered aromatic ring(s) and CH.sub.2C.sub.6Br.sub.5 indicates a pentabromobenzyl group, wherein the benzylic carbon of said CH.sub.2C.sub.6Br.sub.5 group is bonded to a carbon atom of said six-membered aromatic ring(s), and further wherein said homologous series comprises the compound Ar(CH.sub.2C.sub.6Br.sub.5).sub.3m+3, where m+1 is the number of the six-membered aromatic rings in Ar.

Description

EXAMPLES

Example 1

Reaction of Toluene with PBBBr

(1) DBM (200 ml), PBBBr (62.2 g, 0.11 mol) and toluene (3.7 g, 0.04 mol) were placed into a 500 ml flask fitted with a mechanical stirrer, thermometer, condenser and N.sub.2 inlet. The mixture was heated to 70 C. until the PBBBr had dissolved. AlCl.sub.3 (0.7 g, 0.005 mol) was added and the vigorous formation of HBr started. The mixture was heated at 80 C. for 6 hours until the PBBBr disappeared (by GC). The reaction mixture was washed three times with water (3120 ml) and SBS (1.5 ml, 28% aqueous solution) taking 20 minutes for each washing. After that, the solid was filtered out and re-slurried with DCM (2200 ml) at 40 C., for one hour (each reslurry). The reaction mixture was cooled to 20 C. and the solid was filtered off and dried in an oven at 150 C. under reduced pressure for 24 hours, to give 42.7 g, corresponding to 75% yield, based on PBBBr. According to elemental analysis, the content of bromine is about 76% (parabomb), corresponding to 2.7 PBBBr molecules per molecule of toluene. The product of this example is represented by the formula C.sub.6H.sub.2.3(CH.sub.3)(CH.sub.2C.sub.6Br.sub.5).sub.2.7 and is named Tris(pentabromobenzyl)toluene.

Example 2

Reaction of Toluene with PBBBr

(2) The procedure of Example 1 was repeated, but using PBBBr (56.6 g, 0.1 mol), toluene (4.6 g, 0.05 mol), AlCl.sub.3 (2.8 g, 0.02 mol) and dichloroethane (200 ml) as the solvent. The weight of the product was 49.5 g, corresponding to 86% yield, the content of bromine is about 75.0%.

Example 3

Reaction of Diphenyloxide with PBBBr

(3) The procedure of Example 1 was repeated, but using PBBBr (169.8 g, 0.3 mol), diphenyloxide instead of toluene (8.5 g, 0.05 mol) and AlCl.sub.3 (2.8 g, 0.02 mol). The weight of the product was 115.7 g, corresponding to 75% yield, the content of bromine is about 78%.

Example 4

Reaction of Diphenylmethane with PBBBr

(4) The procedure of Example 1 was repeated, but using PBBBr (68 g, 0.12 mol), diphenylmethane instead of toluene (3.3 g, 0.02 mol) and AlCl.sub.3 (1.4 g, 0.01 mol). The weight of the product was 41.8 g, corresponding to 68% yield, the content of bromine is about 77.4%.

Example 5

Reaction of Diphenylethane with PBBBr

(5) The procedure of Example 1 was repeated, but using diphenylethane (3.65 g, 0.02 mol) instead of toluene. The weight of the product was 35.6 g, corresponding to 63% yield, the content of bromine is about 77%.

Example 6

Reaction of Diphenylethane with PBBBr

(6) The procedure of Example 5 was repeated, but using dichloroethane as a solvent. The weight of the product was 46.7 g, corresponding to 83% yield, the content of bromine is about 77%. The product is hexakis(pentabromobenzyl) diphenylethane.

Example 7

Reaction of Diphenylethane with PBBBr

(7) DCE (1600 ml), PBBBr (805.6 g, 1.42 mol) and diphenylethane (57.70 g, 0.317 mol) were placed into a 2000 ml glass reactor fitted with a mechanical stirrer, thermometer, condenser and N.sub.2 inlet. The mixture was heated to 70 C. and AlCl.sub.3 (4.5 g, 0.17 mol) was added portionwise during 3 hours. Then the mixture was heated for an additional hour at 65-75 C. until the PBBBr disappeared (by GC). The reaction mixture was washed three times with water (31000 ml) at 60 C. and SBS (20 ml, 28% aqueous solution) taking 20 minutes for each washing. After that, the solid was filtered off at 40-50 C., washed with 200 ml DCE, and dried in an oven at 150 C. under reduced pressure for 20 hours, to give 738 g, corresponding to an 98% yield. The content of bromine was 75%. The product is pentakis(pentabromobenzyl)diphenylethane.

Examples 8 and 9 (of the Invention) and 10 (Comparative)

V-0 Rated Flame Retarded Formulations of Polyamide 66

(8) The products of Examples 1 and 7 were tested as flame retardants (FR) in nylon compositions according to the procedure described below. A commercially available polymeric flame retardant, FR-803P, was also tested for the purpose of comparison.

(9) Ingredients Used to Prepare the Compositions

(10) The materials used for preparing the nylon compositions are tabulated in Table 1:

(11) TABLE-US-00001 TABLE 1 TRADE NAME (PRODUCER) GENERAL INFORMATION FUNCTION Aculon S 223D Polyamide 66 (contains Plastic matrix (DSM) nucleating agent, mold release agent & lubricant) FR-803P (ICL-IP) Brominated polystyrene FR Product of Example 1 Tris(pentabromobenzyl)toluene FR Product of Example 7 Pentakis(pentabromobenzyl) FR diphenylethane GF ChopVantage 3660 Glass fibers Reinforcing (PPG) filler AO M-0112 Antimony trioxide masterbatch, FR-synergist (Kafrit) 77%, universal grade. Acrawax C Multifunctional, nitrogen- Antioxidant & (Lonza) containing, hindered phenol heat stabilizer Irganox B1171 (Ciba) N,N ethylene bisstearamide Lubricant Ca Stearate Ca-stearate Lubricant
Preparation of the Compositions and Test Specimens

(12) The compounding was performed in a twin-screw co-rotating extruder ZE25 with L/D=32 (Berstorff). PA 66 pellets (which were dried overnight at 80 C. in a vacuum oven), the flame retardant, Acrawax C, Irganox B1171 and Ca stearate were weighed on Sartorius semi-analytical scales with subsequent manual mixing in plastic bags. The blend was then fed via feeder N.sup.o 1. The glass fiber was fed in via feeder N.sup.o 3 to the 5th section of the extruder via a lateral feeder. The compounding conditions are presented in Table 2. The extruded strands were cooled in a water bath and pelletized. The obtained pellets were dried in a vacuum at 80 C. overnight.

(13) TABLE-US-00002 TABLE 2 PARAMETER UNITS Set values Read values Feeding zone temperature (T.sub.1) C. T.sub.2 C. 250 234-256 T.sub.3 C. 270 269-285 T.sub.4 C. 270 259-287 T.sub.5 C. 270 267-270 T.sub.6 C. 270 262-279 T.sub.7 (vent) C. 275 265-286 T.sub.8 C. 275 268-293 T.sub.9 C. 280 264-281 Temperature of melt C. 260-281 Screw speed RPM 300 Feeding rate Kg/h 12

(14) The dried pellets were injection molded into 1.6 thick test specimens using Allrounder 500-150 from Arburg. The conditions of the injection molding are tabulated in Table 3 below:

(15) TABLE-US-00003 TABLE 3 PARAMETER UNITS Set values T.sub.1 (Feeding zone) C. 240 T.sub.2 C. 260 T.sub.3 C. 285 T.sub.4 C. 290 T.sub.5 (nozzle) C. 295 Mold temperature C. 90 Injection pressure bar 1300 Holding pressure bar 700-900 Back pressure bar 10 Injection time sec 40 Holding time sec 6 Cooling time sec 1 Injection speed ccm/sec 50

(16) The specimens were conditioned for at least 48 hours at 23 C., and were then subjected to the tests outlined below.

(17) Tests

(18) Flammability Test

(19) The flammability test was carried out according to the Underwriters-Laboratories standard UL 94, applying the vertical burn on specimens of 1.6 mm thickness.

(20) Mechanical Properties

(21) Impact strength was measured using the Izod notched test according to ASTM D-256, using pendulum impact tester type 5102 (Zwick); Tensile properties (tensile strength, tensile modulus, elongation at yield and elongation at break) were measured in Zwick/Roell Z010 material testing machine according to ASTM D-638 (type 2 dumbbells were used, with the speed of test being 5 mm/min).

(22) Thermal Properties

(23) HDT (heat distortion temperature; this is the temperature at which a polymer sample deforms under a specific load) was measured according to ASTM D-648-72 with load of 18.5 kg/cm.sup.2 and heating rate 2 C./min; MFI (melt flow index) was determined according to ASTM D1238. The compositions tested and the results are set out in Table 4.

(24) TABLE-US-00004 TABLE 4 Example 8 9 10 FR Product of Product of FR 803P Example 1 Example 7 PA 66 (Aculon S 223-D) 46.3 51.3 43.5 GF ChopVantage 3660 30 30 30 FR 16.9 13.3 19.7 AO M-0112 6.3 4.8 6.2 Acrawax C 0.2 0.2 0.2 Irganox B1171 0.2 0.2 0.2 Ca-stearate 0.2 0.2 0.2 Br (calculated) 13 10 13 Sb.sub.2O.sub.3 (calculated) 4.8 3.7 4.8 Br/Sb.sub.2O.sub.3 (calculated) 2.7 2.7 2.7 Total flaming time 10 19 32 Max. flaming time 1 5 8 No. of dripping 0 5 0 No. of cotton ignition 0 0 0 Rating V-0 V-0 V-0 Izod Impact 104 103 111 Tensile strength 150 150 143 Elongation at yield 2.6 3.3 3 Elongation at break 4.2 4.7 3.3 Tensile modulus 10747 9948 10044 MFI 11 29 7 HDT 226 231 225

Examples 11-13

V-2 and V-0 Rated Flame Retarded Formulations of Polypropylene Impact Copolymers

(25) The product of Example 7, pentakis(pentabromobenzyl) diphenylethane, was tested in compositions of polypropylene impact copolymers according to the procedure described below.

(26) Ingredients Used to Prepare the Compositions

(27) The materials used for preparing the polypropylene compositions are tabulated in Table 5:

(28) TABLE-US-00005 TABLE 5 Component (manufacturer) GENERAL DESCRIPTION FUNCTION PP Capilene polypropylene impact copolymer plastic matrix SL-50 (Caol) Product of Pentakis(pentabromobenzyl) flame retardant Example 7 diphenylethane FR00112 Antimony trioxide masterbatch which FR synergist (Kafrit) contains 80 wt % Sb.sub.2O.sub.3 Lotalc Talc Filler Irganox B 225 Antioxidant/processing stabilizer Antioxidant & (Ciba) Irganox 1010:Irgafos 168 1:1 blend heat stabilizer.
Preparation of Compositions and Test Specimens

(29) The ingredients were pre-mixed, and fed via volumetric feeder #2 to the port of a twin-screw co-rotating extruder ZE25 with L/D=32 from Berstorff. Specific conditions are presented in Table 6:

(30) TABLE-US-00006 TABLE 6 PARAMETER UNITS Set values Screws Medium shear A Feeding zone C. no temperature (T.sub.1) heating T.sub.2 C. 160 T.sub.3 C. 180 T.sub.4 C. 200 T.sub.5 C. 200 T.sub.6 C. 210 T.sub.7 C. 210 T.sub.8 C. 220 T.sub.9 C. 230 Screw speed RPM 350 Feeding rate Kg/h 15

(31) The strands produced were pelletized in a pelletizer 750/3 from Accrapak Systems Ltd. The resultant pellets were dried in a circulating air oven at 80 C. for 3 hours. The dried pellets were injection molded into test specimens using Allrounder 500-150 from Arburg as tabulated Table in 7.

(32) TABLE-US-00007 TABLE 7 PARAMETER UNITS Set values T.sub.1 (Feeding zone) C. 50 T.sub.2 C. 220 T.sub.3 C. 220 T.sub.4 C. 220 T.sub.5 (nozzle) C. 230 Mold temperature C. 40 Injection pressure bar 600 Holding pressure bar 450 Back pressure bar 60 Holding time sec 5 Cooling time sec 18 Mold closing force kN 500 Filling volume (portion) ccm 38 Injection speed ccm/sec 30

(33) The specimens were conditioned for one week at 23 C., and were then subjected to the tests outlined below.

(34) Tests

(35) Flammability Test

(36) The flammability test was carried out according to the Underwriters-Laboratories standard UL 94, applying the vertical burn on specimens of 1.6 mm thickness.

(37) Mechanical Properties

(38) Impact strength was measured using the Izod notched test according to ASTM D-256-81, using pendulum impact tester type 5102 (Zwick); Tensile properties (tensile strength, tensile modulus, elongation at break) were measured in Zwick/Roell Z010 material testing machine according to ASTM D-638-95 (v=5, test speed 10 mm/min).

(39) Thermal Properties

(40) HDT (heat distortion temperature; this is the temperature at which a polymer sample deforms under a specific load) was measured according to ASTM D-648-72 with load of 1820 kPa and heating rate of 120 C./hour; the instrument is HDT/Viact-plus from Davenport, Lloyd instruments. MFI (melt flow index) was determined according to ASTM D1238 (230 C./2.16 kg); the instrument is Meltflixer 2000 from Thermo Hake. The compositions tested and the results are set out in Table 8.

(41) TABLE-US-00008 TABLE 8 Example 10 11 12 Composition (by weight %): Polypropylene impact copolymer 56.7 55.1 53.3 FR of Example 7 29.3 22.7 24.0 Lotalc 25 15.0 15.0 Antimony trioxide masterbatch 13.8 7.1 7.5 Irganox B 225 0.2 0.2 0.2 Bromine content, % calculated 22.0 17.0 18.0 Antimony trioxide, % calculated 11.0 5.7 6.0 Bromine/Sb.sub.2O.sub.3 ratio 2.0 3.0 3.0 Properties Flammability test: UL-94 vertical burning test at 1.6 mm thickness Maximal flaming time (sec) 6 10 6 Total Flaming time (sec) 16 42 28 Number of Specimens dripped 5 5 5 Number of cotton ignition 0 1 0 Rating V-0 V-2 V-0 Mechanical Properties Impact strength (J/m) 27 nd 28 Tensile strength (N/mm2) 17.2 nd 18 Elongation at break (%) 64 nd 27 Tensile modulus (N/mm2) 1490 nd 2060 Thermal properties HDT ( C.) 63 nd 67 MFI (g/10 min) 4.1 nd 3.5

Example 14

V-0 Rated Flame Retarded Formulation of ABS

(42) The product of Example 7, pentakis(pentabromobenzyl) diphenylethane, was tested in compositions of ABS according to the procedure described below.

(43) Ingredients Used to Prepare the Compositions

(44) The materials used for preparing the ABS compositions are tabulated in Table 9:

(45) TABLE-US-00009 TABLE 9 Component (manufacturer) GENERAL DESCRIPTION FUNCTION ABS Magnum Acrylonitrile-butadiene-styrene plastic matrix 3404 (Styron) copolymer Product of Pentakis(pentabromobenzyl) flame retardant Example 7 diphenylethane FR00112 Antimony trioxide masterbatch which FR synergist (Kafrit) contains 80 wt % Sb.sub.2O.sub.3 Hostaflon 2017 PTFE Anti-dripping (Dyneon) agent Irganox B 225 Phenol:Phosphite 3:1 based stabilizer Antioxidant & (Ciba) heat stabilizer.
Preparation of Compositions and Test Specimens

(46) The compounding was performed in a twin-screw co-rotating extruder ZE25 with L/D=32 from Berstorff. Specific conditions are presented in Table 10.

(47) TABLE-US-00010 TABLE 10 PARAMETER UNITS Set values Screws Medium shear A Feeding zone C. no temperature (T.sub.1) heating T.sub.2 C. 180 T.sub.3 C. 200 T.sub.4 C. 210 T.sub.5 C. 210 T.sub.6 C. 210 T.sub.7 C. 220 T.sub.8 C. 230 T.sub.9 C. 240 Screw speed RPM 350 Feeding rate Kg/h 15

(48) The strands produced were pelletized in a pelletizer 750/3 from Accrapak Systems Ltd. The resultant pellets were dried in a circulating air oven at 80 C. for 3 hours. The dried pellets were injection molded into test specimens using Allrounder 500-150 from Arburg as tabulated in Table 11.

(49) TABLE-US-00011 TABLE 11 PARAMETER UNITS Set values T.sub.1 (Feeding zone) C. 210 T.sub.2 C. 215 T.sub.3 C. 220 T.sub.4 C. 230 T.sub.5 (nozzle) C. 230 Mold temperature C. 40 Injection pressure bar 900 Holding pressure bar 800 Back pressure bar 50 Holding time sec 7 Cooling time sec 10 Mold closing force kN 500 Filling volume (portion) ccm 38 Injection speed ccm/sec 25

(50) The specimens were conditioned for one week at 23 C., and were then subjected to the tests outlined below.

(51) Tests

(52) Flammability Test

(53) The flammability test was carried out according to the Underwriters-Laboratories standard UL 94, applying the vertical burn on specimens of 1.6 mm thickness.

(54) Mechanical Properties

(55) Impact strength was measured using the Izod notched test according to ASTM D-256-81; Tensile properties (tensile strength, tensile modulus, elongation at break) were measured in Zwick/Roell Z010 material testing machine according to ASTM D-638-95 (v=50 mm/min).

(56) Thermal Properties

(57) HDT was measured according to ASTM D-648-72 with load of 1820 kPa and heating rate of 120 C./hour; the instrument is HDT/Vicat-plus from Davenport, Lloyd instruments. MFI (melt flow index) was determined according to ASTM D1238 (200 C./5 kg); the instrument is Meltflixer 2000 from Thermo Hake. The compositions tested and the results are set out in Table 12.

(58) TABLE-US-00012 TABLE 12 Example 14 Composition (by weight %): ABS 80.4 FR of Example 7 17.4 Antimony trioxide masterbatch 1.9 PTFE 0.1 Irganox B 225 0.2 Bromine content, % calculated 13.0 Antimony trioxide, % calculated 1.5 Bromine/Sb.sub.2O.sub.3 ratio 8.66 Properties Flammability test: UL-94 vertical burning test at 1.6 mm thickness Maximal flaming time (sec) 9 Total Flaming time (sec) 24 Max glowing time 0 Number of specimens which dripped 0 Number of cotton ignition 0 Number of specimen burned up to the clamp 0 Rating V-0 Mechanical Properties Impact strength (J/m) 104 Tensile strength (N/mm2) 39 Elongation at break (%) 13 Tensile modulus (N/mm2) 2161 Thermal properties HDT ( C.) 78 MFI (g/10 min) 11.7