Process For Preparing Ethylenedialkylphosphinic Acids, Esters And Salts And Use Thereof

Abstract

The invention relates to a method for producing ethylenedialkylphosphinic acids, esters and salts, and to the use thereof as flame retardants. The claimed method is characterised in that •a) a phosphinic acid source (I) is reacted with olefins (IV) in the presence of catalyst A so as to obtain an alkylphosphonous acid, salt or ester (II) thereof, and •b) the alkylphosphonous acid, salt or ester (II) thereof obtained in this manner is reacted with acetylenic compound (V) in the presence of catalyst B in order to obtain the ethylenedialkylphosphinic acid derivative (III), •catalyst A being transition metals and/or transition metal compounds and/or catalyst systems composed of a transition metal and/or a transition metal compound and at least one ligand •and catalyst B being electromagnetic radiation.

##STR00001##

Claims

1. A process for preparing ethylenedialkylphosphinic acids, esters and salts, comprising the steps of: a) reacting a phosphinic acid source (I) ##STR00006## with olefins (IV) ##STR00007## in the presence of a catalyst A to give an alkylphosphonous acid (II), or salt or ester thereof ##STR00008## b) reacting the alkylphosphonous acid (II), or salt or ester thereof, thus formed with an acetylenic compound (V)
R.sup.5R.sup.6   (V) in the presence of a catalyst B to give the ethylenedialkylphosphinic acid derivative (III) ##STR00009## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.11, R.sup.12, R.sup.13, R.sup.14 are the same or different and are each independently H, C.sub.1-C.sub.18-alkyl, C.sub.6-C.sub.18-aryl, C.sub.6-C.sub.18-aralkyl, C.sub.6-C.sub.18-alkylaryl, where the C.sub.6-C.sub.18-aryl, C.sub.6-C.sub.18-aralkyl, C.sub.6-C.sub.18-alkylaryl groups are, optionally, substituted by —C(O)CH.sub.3, OH, CH.sub.2OH, NH.sub.2, NO.sub.2, OCH.sub.3, SH and/or OC(O)CH.sub.3, and X is Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Zn, Ce, Bi, Sr, Mn, Cu, Ni, Li, Na, K, H and/or a protonated nitrogen base, and/or is H, C.sub.1-C.sub.18-alkyl, C.sub.6-C.sub.18-aryl, C.sub.6-C.sub.18-aralkyl, C.sub.6-C.sub.18-alkylaryl, (CH.sub.2).sub.kOH, CH.sub.2—CHOH—CH.sub.2OH, (CH.sub.2).sub.kO(CH.sub.2).sub.IH, (CH.sub.2).sub.k—CH(OH)—(CH.sub.2).sub.IH, (CH.sub.2—CH.sub.2O).sub.kH, (CH.sub.2—C[CH.sub.3]HO).sub.kH, (CH.sub.2—C[CH.sub.3]HO).sub.k(CH.sub.2—CH.sub.20).sub.IH, (CH.sub.2—CH.sub.2O).sub.k(CH.sub.2—C[CH.sub.3]HO)H, (CH.sub.2—CH.sub.2O).sub.k-alkyl, (CH.sub.2—C[CH.sub.3]HO).sub.k-alkyl, (CH.sub.2—C[CH.sub.3]HO).sub.k(CH.sub.2—CH.sub.20).sub.I-alkyl, (CH.sub.2—CH.sub.2O).sub.k(CH.sub.2—C[CH.sub.3]HO)O-alkyl, (CH.sub.2).sub.kNH.sub.2, (CH.sub.2).sub.kN[(CH.sub.2).sub.IH].sub.2, where k and I are the same or different and are each independently an integer from 0 to 20, and m is 1 to 4, and the catalyst A is selected from the group consisting of transition metals, transition metal compounds, catalyst systems composed of a transition metal and/or a transition metal compound and at least one ligand and a combination thereof, and the catalyst B is electromagnetic radiation.

2. The process as claimed in claim 1, wherein the alkylphosphonous acid (II), or salt or ester thereof, obtained after step a) is esterified with an alkene oxide or an alcohol, and the alkylphosphonous ester (II) and/or ethylenedialkylphosphinic ester (III) formed is subjected to the reaction step b).

3. The process as claimed in claim 1, wherein the ethylenedialkylphosphinic acid (III), or salt or ester thereof, obtained after step b) is esterified with an alkene oxide or an alcohol M—OH and/or M′—OH.

4. The process as claimed in claim 1, wherein the ethylenedialkylphosphinic acid (III), or salt or ester thereof, obtained after step b) is subsequently reacted, in a step c), with metal compounds of Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Zn, Ce, Bi, Sr, Mn, Li, Na, a protonated nitrogen base or a combination thereof to give the corresponding ethylenedialkylphosphinic salts (III) of these metals and/or of a nitrogen compound.

5. The process as claimed in claim 1, wherein .sub.R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.11, R.sup.12, R.sup.13, R.sup.14 are the same or different and are each independently H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl or a combination thereof.

6. The process as claimed in claim 1, wherein X is H, Ca, Mg, Al, Zn, Ti, Mg, Ce, Fe, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl, poly(oxyethylene), oxypropylene, poly(oxypropylene), oxybutylene, poly(oxybutylene), allyl ether or a combination thereof.

7. The process as claimed in claim 1, wherein the transition metals are rhodium, nickel, palladium, platinum, ruthenium or a combination thereof.

8. The process as claimed in claim 1, wherein gaseous olefins are used.

9. The process as claimed in claim 8, wherein the gaseous olefins are ethylene, propylene, 1-butene, 2-butene, 2-methylpropylene or a combination thereof.

10. The process as claimed in claim 1, wherein the temperature in reaction step a) is 40-120° C. and that in reaction step b) is 30-100° C.

11. The process as claimed in claim 1, wherein the temperature in reaction step a) is 60-100° C. and that in reaction step b) is 50-80° C.

12. The process as claimed in claim 1, wherein the pressure in each of reaction step a) and reaction step b) is 0-10 bar.

13. The process as claimed in claim 1, wherein the pressure in each of reaction step a) and reaction step b) is 1-5 bar and the gas flow in each of reaction step a) and reaction step b) is 5-12 L/h.

14. The process as claimed in claim 1, wherein the electromagnetic radiation is UV radiation.

15. The process as claimed in claim 1, wherein the electromagnetic radiation is UV radiation having a wavelength between 400 and 10 nm.

16. The process as claimed in claim 1, wherein the acetylenic compound (V) is acetylene, methylacetylene, 1-butyne, 1-hexyne, 2-hexyne, 1-octyne, 4-octyne, 1-butyn-4-ol, 2-butyn-1-ol, 3-butyn-1-ol, 5-hexyn-1-ol, 1-octyn-3-ol, 1-pentyne, phenylacetylene, trimethylsilylacetylene or a combination thereof.

17. The process as claimed in claim 1, wherein the acetylenic compound (V) is acetylene.

18. The process as claimed in claim 3, wherein the alcohol M—OH is a linear or branched, saturated or unsaturated, monohydric alcohol and the alcohol M′—OH is a polyhydric organic alcohol each having a carbon chain length of C.sub.1-C.sub.18.

19. A composition selected from the group consisting of an intermediate for further syntheses, a binder, a crosslinker or accelerator in the curing of epoxy resins, polyurethanes and unsaturated polyester resins, a polymer stabilizer, a crop protection agent, a sequestrant, a mineral oil additive, an anticorrosive, a washing or cleaning composition, an electronics application composition, a flame retardant, a flame retardant for clearcoats and intumescent coatings, a flame retardant for wood and other cellulosic products, a reactive and/or nonreactive flame retardant for polymers, a flame-retardant polymer molding composition, a flame-retardant polymer molding, a pure or blended polyester or cellulose fabrics flame-retardant, a flame retardant for the production and curing of epoxy resins and polyurethanes or unsaturated polyester resins for electronics applications manufactured with ethylenedialkylphosphinic acids, esters and salts made in accordance with the process of claim 1.

20. A flame-retardant thermoplastic or thermoset polymer molding composition, molding, film, filament or fiber comprising 0.5% to 45% by weight of ethylenedialkylphosphinic acids, salts or esters made by the process of claims 1, 0.5% to 99.5% by weight of thermoplastic or thermoset polymer or mixtures thereof, 0% to 55% by weight of additives and 0% to 55% by weight of filler or reinforcing materials, where the sum of the components is 100% by weight.

21. The composition as claimed in claim 19, wherein the composition is selected from the group consisting of epoxy resins, polyurethanes and unsaturated polyester resins and wherein the epoxy resins, polyurethanes and unsaturated polyester resins are in the form of polymer moldings and further comprise hardeners, UV stabilizers, flexibilizers and/or other additives.

22. The composition as claimed in claim 19, wherein the ethylenedialkylphosphinic acid is ethylenediethylphosphinic acid.

Description

EXAMPLE 1

[0207] At room temperature, a three-neck flask with stirrer and jacketed coil condenser is initially charged with 580 g of tetrahydrofuran, which is “degassed” by passing nitrogen through for 10 minutes while stirring, and the further operations are executed under nitrogen. 70.0 mg of tris(dibenzylideneacetone)dipalladium and 95.0 mg of 4,5-bis(diphenyl-phosphino)-9,9-dimethylxanthene are added thereto and the mixture is stirred for a further 15 minutes, then 198 g of phosphinic acid in 198 g of water are added and nitrogen is passed through the reaction mixture for 10 minutes. The reaction solution is transferred into a 2 L BUchi reactor and the three-neck flask is rinsed with tetrahydrofuran. While stirring the reaction mixture, the reactor is charged with ethylene to 2.5 bar and the reaction mixture is heated to 80° C. (jacket temperature). After stoichiometric absorption of ethylene, the mixture is cooled to room temperature and free ethylene is discharged by burning it off.

[0208] The reaction mixture is freed of the solvent on a rotary evaporator at a maximum of 60° C. and 350-10 mbar. The residue is admixed with 300 g of DM water and stirred at room temperature under a nitrogen atmosphere for 1 hour. The resultant residue is filtered and the filtrate is extracted with 200 mL of toluene. The aqueous phase is freed of the solvent on a rotary evaporator at a maximum of 60° C. and 250-10 mbar.

[0209] Yield: 276 g of ethylphosphonous acid (98% of theory).

EXAMPLE 2

[0210] At room temperature, a three-neck flask with stirrer and jacketed coil condenser is initially charged with 550 g of butanol, which is degassed by passing nitrogen through while stirring, and the further operations are executed under nitrogen.

[0211] Then 73.8 mg of tris(dibenzylideneacetone)dipalladium and 100.2 mg of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are added thereto and the mixture is stirred, then 209 g of phosphinic acid in 209 g of water are added. The reaction solution is transferred into a 2 L Büchi reactor which is charged with ethylene to 1 bar while stirring and the reaction mixture is heated to 100° C. After stoichiometric absorption of ethylene, the mixture is cooled and free ethylene is discharged. The reaction mixture is freed of the solvent on a rotary evaporator. 100 g of DM water are added to the residue, the mixture is stirred at room temperature and then filtered, the filtrate is extracted with toluene and freed of the solvent on a rotary evaporator, and the resulting ethylphosphonous acid is collected.

[0212] Yield: 295 g (99% of theory).

EXAMPLE 3

[0213] At room temperature, a three-neck flask with stirrer and jacketed coil condenser is initially charged with 600 g of acetonitrile, which is degassed by passing nitrogen through while stirring, and the further operations are executed under nitrogen. 53.1 mg of tris(dibenzylideneacetone)dipalladium and 72.1 mg of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are added thereto and the mixture is stirred, then 150 g of phosphinic acid in 150 g of toluene are added. The reaction solution is transferred into a 2 L Büchi reactor which is charged with ethylene to 5 bar while stirring and the reaction mixture is heated to 70° C. After stoichiometric absorption of ethylene, the mixture is cooled and free ethylene is discharged. The reaction mixture is freed of the solvent on a rotary evaporator. 100 g of DM water are added to the residue, the mixture is stirred at room temperature and then filtered, the filtrate is extracted with toluene and freed of the solvent on a rotary evaporator, and the resulting ethylphosphonous acid is collected.

[0214] Yield: 212 g (99% of theory).

EXAMPLE 4

[0215] At room temperature, a three-neck flask with stirrer and jacketed coil condenser is initially charged with 188 g of water, which is degassed by passing nitrogen through while stirring, and the further operations are executed under nitrogen. 0.2 mg of palladium(II) sulfate and 2.3 mg of tris(3-sulfophenyl)phosphine trisodium salt are added thereto and the mixture is stirred, then 66 g of phosphinic acid in 66 g of water are added. The reaction solution is transferred into a 2 L BUchi reactor which is charged with ethylene to 1 bar while stirring and the reaction mixture is heated to 80° C. After stoichiometric absorption of ethylene, the mixture is cooled and free ethylene is discharged. The reaction mixture is freed of the solvent on a rotary evaporator. 100 g of DM water are added to the residue, the mixture is stirred at room temperature and then filtered, the filtrate is extracted with toluene and freed of the solvent on a rotary evaporator, and the resulting ethylphosphonous acid is collected.

[0216] Yield: 92 g (98% of theory).

EXAMPLE 5

[0217] At room temperature, a three-neck flask with stirrer, thermometer and jacketed coil condenser is initially charged with 188 g of butanol, which is degassed by passing nitrogen through while stirring, and the further operations are executed under nitrogen. 0.2 mg of tris(dibenzylideneacetone)dipalladium and 2.3 mg of 4,5-bis(diphenyl-phosphino)-9,9-dimethylxanthene, 66 g of phosphinic acid in 66 g of water and 117 g of octene are added thereto, and the mixture is stirred.

[0218] Subsequently, the reaction mixture is heated to 80° C. for 6 h and freed of the solvent on a rotary evaporator. The residue is admixed with 100 g of toluene and extracted with water, then the organic phase is freed from the solvent on a rotary evaporator and the resulting octanephosphonous acid is collected.

[0219] Yield: 176 g (98% of theory).

EXAMPLE 6

[0220] As in example 2, 99 g of phosphinic acid, 396 g of butanol, 42 g of ethylene, 6.9 mg of tris(dibenzylideneacetone)dipalladium and 9.5 mg of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are converted, then purified by passing through a column filled with Deloxan® THP II, and n-butanol is added once again. At a reaction temperature of 80-110° C., the water formed is removed by azeotropic distillation. The butyl ethylphosphonite product is purified by distillation under reduced pressure.

[0221] Yield: 189 g (84% of theory).

EXAMPLE 7

[0222] As in example 2, 198 g of phosphinic acid, 198 g of water, 84 g of ethylene, 6.1 mg of palladium(II) sulfate and 25.8 mg of 9,9-dimethyl-4,5-bis(diphenylphosphino)-2,7-sulfonatoxanthene disodium salt are converted, then passed through a column filled with Deloxan® THP II, and then n-butanol is added. At a reaction temperature of 80-110° C., the water formed is removed by azeotropic distillation. The butyl ethylphosphonite product is purified by distillation under reduced pressure.

[0223] Yield: 374 g (83% of theory).

EXAMPLE 8

[0224] A 500 mL five-neck flask with gas inlet tube, thermometer, jacketed coil condenser and a reflux condenser with gas combustion is initially charged with 94 g (1 mol) of ethylphosphonous acid (prepared as in example 2). At room temperature, ethylene oxide is introduced, a reaction temperature of 70° C. is established and reaction is continued at 80° C. for another hour. The ethylene oxide absorption is 65.7 g. The acid number of the product is less than 1 mg KOH/g. Yield: 129 g (94% of theory) of 2-hydroxyethyl ethylphosphonite as colorless, water-clear product.

EXAMPLE 9

[0225] A 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9) is initially charged with 94.0 g of ethylphosphonous acid (prepared as in example 2) in 200 g of acetic acid. At the same time, through the gas inlet frit, about 8 L/h of acetylene are passed through the solution. The reaction temperature is kept at 60° C. by means of a cooling bath. After 8 h, the acetylene stream is closed and the acetylene is removed by passing nitrogen through. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals.

[0226] Yield: 87 g (81% of theory).

EXAMPLE 10

[0227] In a 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9), 94.0 g of ethylphosphonous acid (prepared as in example 2) are dissolved in 200 g of tetrahydrofuran.

[0228] At the same time, through the gas inlet frit, about 8 L/h of acetylene are passed through the solution. The reaction temperature is kept at 40° C. by means of a cooling bath. After 8 h, the acetylene stream is closed and the acetylene is removed by passing nitrogen through. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals.

[0229] Yield: 79 g (74% of theory).

EXAMPLE 11

[0230] A 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9) is initially charged with 94.0 g of ethylphosphonous acid (prepared as in example 2) in 200 g of acetonitrile. At the same time, through the gas inlet frit, about 10 L/h of acetylene are passed through the solution. The reaction temperature is kept at 50° C. by means of a cooling bath. After 6 h, the acetylene stream is closed. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals. These are filtered off.

[0231] Yield: 92 g (86% of theory).

EXAMPLE 12

[0232] In a 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9), 94.0 g of ethylphosphonous acid (prepared as in example 2) are dissolved in 200 g of water.

[0233] At the same time, through the gas inlet frit, about 15 L/h of acetylene are passed through the solution for 5 h. The reaction temperature is kept at 30° C. by means of a cooling bath. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals. These are filtered off.

[0234] Yield: 83 g (78% of theory).

EXAMPLE 13

[0235] A 2 L Büchi autoclave equipped with gas inlet frit, thermometer, stirrer and UV lamp (0.125 kW, cos φ0.9) is initially charged with 94.0 g of ethylphosphonous acid (prepared as in example 2) in 400 g of acetonitrile and pressurized with acetylene to 3 bar. The reaction temperature is kept at 50° C. by means of the water cooling. After 6 h, the reaction is ended. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals. These are filtered off.

[0236] Yield: 95 g (89% of theory).

EXAMPLE 14

[0237] A 2 L Büchi autoclave equipped with gas inlet frit, thermometer, stirrer and UV lamp (0.125 kW, cos φ0.9) is initially charged with 94.0 g of ethylphosphonous acid (prepared as in example 2) in 350 g of water and pressurized with acetylene to 1.2 bar. The reaction temperature is kept at 60° C. by means of the water cooling. After 8 h, the reaction is ended. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals, which are filtered off.

[0238] Yield: 88 g (82% of theory).

EXAMPLE 15

[0239] A 2 L Büchi autoclave equipped with gas inlet frit, thermometer, stirrer and UV lamp (0.125 kW, cos φ0.9) is initially charged with 94.0 g of ethylphosphonous acid (prepared as in example 2) in 300 g of butanol and pressurized with acetylene to 2 bar. The reaction temperature is kept at 80° C. by means of the water cooling. After 4 h, the reaction is ended. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals. These are filtered off.

[0240] Yield: 94 g (88% of theory).

EXAMPLE 16

[0241] In a 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9), 99.0 g of ethylphosphonous acid (prepared as in example 2) are dissolved in 250 g of butanol.

[0242] At the same time, through the gas inlet frit, about 1 L/h of acetylene is passed through the solution for 15 h. The reaction temperature is kept at 80° C. by means of a cooling bath. The ethylenebis(ethylphosphinic acid) precipitates out in the form of colorless crystals. These are filtered off and washed with butanol.

[0243] Yield: 79 g (70% of theory).

EXAMPLE 17

[0244] In a 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and UV lamp (0.125 kW, cos φ0.9), 122 g of octanephosphonous acid (prepared as in example 3) are dissolved in 250 g of butanol.

[0245] At the same time, through the gas inlet frit, about 8 L/h of acetylene are passed through the solution for 5 h. The reaction temperature is kept at 60° C. by means of a cooling bath. After removal of the solvent on a rotary evaporator and extraction with toluene, the ethylenebis(octylphosphinic acid) is obtained in a yield of 59 g (81% of theory).

EXAMPLE 18

[0246] 321 g (1.5 mol) of ethylenebis(ethylphosphinic acid) (prepared as in example 11) are dissolved at 85° C. in 400 mL of toluene, and 888 g (12 mol) of butanol are added. At a reaction temperature of about 100° C., the water formed is removed by azeotropic distillation. After purification by chromatography, 401 g (83% of theory) of ethylenebis(ethylphosphinic acid butyl ester) are obtained.

EXAMPLE 19

[0247] 321 g (1.5 mol) of ethylenebis(ethylphosphinic acid) (prepared as in example 11) are dissolved at 85° C. in 400 mL of toluene, 409 g (6.6 mol) of ethylene glycol are added and esterification is effected in a distillation apparatus with a water separator at about 100° C. over 4 h. After the esterification has ended, the toluene and excess ethylene glycol are removed under reduced pressure. 448 g (99% of theory) of ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) are obtained as a colorless oil.

EXAMPLE 20

[0248] To 326 g (1 mol) of ethylenebis(ethylphosphinic acid butyl ester) (prepared according to example 16) are added 155 g (2.5 mol) of ethylene glycol and 0.4 g of potassium titanyloxalate, and the mixture is stirred at 200° C. for 2 h. By gradual evacuation, volatile components are distilled off. 296 g (98% of theory) of ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) are obtained.

EXAMPLE 21

[0249] A 500 mL five-neck flask with gas inlet tube, thermometer, jacketed coil condenser and reflux condenser with gas combustion is initially charged with 214 g (1 mol) of ethylenebis(ethylphosphinic acid), prepared as in example 11. At room temperature, ethylene oxide is introduced. While cooling, a reaction temperature of 70° C. is established and reaction is continued at 80° C. for another hour. The ethylene oxide absorption is 64.8 g. The acid number of the product is less than 1 mg KOH/g. 257 g (95% of theory) of ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) are obtained as a colorless, water-clear liquid.

EXAMPLE 22

[0250] 642 g (3 mol) of ethylenebis(ethylphosphinic acid) (prepared as in example 11) are dissolved in 860 g of water and initially charged in a 5 L five-neck flask with thermometer, reflux condenser, jacketed coil condenser and dropping funnel and neutralized with about 960 g (12 mol) of 50% sodium hydroxide solution. At 85° C., a mixture of 2583 g of a 46% aqueous solution of Al.sub.2(SO.sub.4).sub.3.14 H.sub.2O is added. Subsequently, the solid obtained is filtered off, washed with hot water and dried at 130° C. under reduced pressure. Yield: 642 g (93% of theory) of colorless ethylenebis(ethylphosphinic acid) aluminum(III) salt.

EXAMPLE 23

[0251] 214 g (1 mol) of ethylenebis(ethylphosphinic acid) (prepared as in example 11) and 170 g of titanium tetrabutoxide are heated under reflux in 500 mL of toluene for 40 hours. Butanol formed is distilled off from time to time with portions of toluene. The solution formed is subsequently freed of the solvent. This gives 229 g of ethylenebis(ethylphosphinic acid) titanium salt.

[0252] Use Examples:

EXAMPLE 24

[0253] To 39.1 g of ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester), prepared as in example 18, are added 290 g of terephthalic acid, 188 g of ethylene glycol and 0.34 g of zinc acetate, and the mixture is heated to 200° C. for 2 h. Then 0.29 g of trisodium phosphate anhydrate and 0.14 g of antimony(III) oxide are added, and the mixture is heated to 280° C. and then evacuated. Specimens of thickness 1.6 mm are then produced by injection molding from the resulting melt (363 g, phosphorus content: 2.2%) for the measurement of the oxygen index (LOI) to ISO 4589-2 and for the UL 94 fire test (Underwriter Laboratories). The specimens thus produced gave an LOI of 42 and achieved UL 94 fire class V-0. Corresponding specimens without ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) gave an LOI of only 31 and achieved only UL 94 fire class V-2.

[0254] The polyester molding containing ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) thus clearly exhibits very good flame-retardant properties.

EXAMPLE 25

[0255] To 19.6 g of ethylenebis(ethylphosphinic acid), prepared analogously to example 11, are added 12.9 g of 1,3-propylene glycol, and the water formed in the esterification is drawn off at 160° C. Then 378 g of dimethyl terephthalate, 192 g of 1,3-propanediol, 0.22 g of tetrabutyl titanate and 0.05 g of lithium acetate are added and the mixture is heated to 130 to 180° C. while stirring for 2 h, then under reduced pressure to 270° C. The polymer (418 g) contains 1.4% phosphorus; the LOI is 38.

EXAMPLE 26

[0256] To 19.7 g of ethylenebis(ethylphosphinic acid) (prepared as in example 11) are added 367 g of dimethyl terephthalate, 238 g of 1,4-butanediol, 0.22 g of tetrabutyl titanate and 0.05 g of lithium acetate, and the mixture is heated to 130 to 180° C. while stirring for 2 h, then under reduced pressure to 270° C. The polymer (432 g) contains 1.3% phosphorus; the LOI is 34, whereas that of untreated polybutylene terephthalate is only 23.

EXAMPLE 27

[0257] In a 250 mL five-neck flask with reflux condenser, stirrer, thermometer and nitrogen inlet, 100 g of a bisphenol A bisglycidyl ether having an epoxy value of 0.55 mol/100 g (Beckopox EP 140, from Solutia) and 13.9 g (0.13 mol) of ethylenebis(ethylphosphinic acid) (prepared analogously to example 11) are heated to a maximum of 150° C. while stirring. After 30 min, a clear melt is obtained. After stirring at 150° C. for a further hour, the melt is cooled and crushed with a mortar and pestle. This gives 117.7 g of a white powder having a phosphorus content of 3.5%.

EXAMPLE 28

[0258] In a 2 L flask with stirrer, water separator, thermometer, reflux condenser and nitrogen inlet, 29.4 g of phthalic anhydride, 19.6 g of maleic anhydride, 24.8 g of propylene glycol, 20.4 g of ethylenebis(ethylphosphinic acid 2-hydroxyethyl ester) (prepared as in example 18), 20 g of xylene and 50 mg of hydroquinone are heated to 100° C. while stirring and passing nitrogen through. When the exothermic reaction sets in, the heating is removed. After the reaction has abated, stirring is continued at about 190° C. After 14 g of water have separated out, the xylene is distilled off and the polymer melt is cooled. This gives 86.2 g of a white powder having a phosphorus content of 4.8%.

EXAMPLE 29

[0259] A mixture of 50% by weight of polybutylene terephthalate, 20% by weight of 3-ethylenebis(ethylphosphinic acid) aluminum(III) salt (prepared as in example 20) and 30% by weight of glass fibers is compounded in a twin-screw extruder (model: Leistritz LSM 30/34) at temperatures of 230 to 260° C. to give a polymer molding composition. The homogenized polymer strand is drawn off, cooled in a water bath and then pelletized. After drying, the molding compositions are processed in an injection molding machine (model: Aarburg Allrounder) at 240 to 270° C. to give polymer moldings and a UL-94 classification of V-0 is determined.

EXAMPLE 30

[0260] A mixture of 53% by weight of nylon-6,6, 30% by weight of glass fibers and 17% by weight of 3-ethylenebis(ethylphosphinic acid) titanium salt (prepared as in example 21) is compounded in a twin-screw extruder (model: Leistritz LSM 30/34) to give polymer molding compositions. The homogenized polymer strand is drawn off, cooled in a water bath and then pelletized. After drying, the molding materials are processed in an injection molding machine (model: Aarburg Allrounder) at 260 to 290° C. to give polymer moldings, and a UL-94 classification of V-0 is obtained.

[0261] The epoxy resin formulations described further up were used to produce polymer moldings. For this purpose, the individual components are weighed out and mixed with one another in a suitable vessel at high stirrer speed. Room temperature solid resins are melted beforehand. After mixing, the resin mixture is devolatilized by applying reduced pressure.

[0262] The finished resin mixture is introduced into a suitable casting mold and hardened at room temperature or in a drying cabinet. The thickness of the polymer moldings produced was 3 mm or 1.6 mm.

[0263] In addition to the flammability class according to UL 94, the Charpy impact resistance (DIN EN ISO 179-1) and the hydrolysis stability were preferably tested on the polymer moldings produced.

[0264] To determine the hydrolysis stability, polymer moldings were stored in each case at 100° C. in 80 mL of water for 24 h. After storage, the phosphorus content of the water was determined.

[0265] In the studies conducted, it was found that the ethylenediethylphosphinic acid prepared in accordance with the invention, in addition to very good flame-retardant action, also reduces the brittleness of the hardened epoxy resin matrix, and is not hydrolyzed in the course of water storage.

[0266] The result is explained hereinafter by additional examples:

[0267] To produce the flame-retardant epoxy resin formulations, the following compounds were used:

[0268] Beckopox® EP 140 (BPA-EP resin, Solutia, United States)

[0269] PF® 0790 K04 (phenol novolac, Hexion Chemical, United States)

[0270] 2-Phenylimidazole (Degussa/Trostberg, Germany)

[0271] TS®-601 (aluminum trihydroxide, Martinswerk, Germany)

[0272] DOPO®-HQ (10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phospha-phenanthrene 10-oxide, Sanko Co., Ltd., Japan)

EXAMPLE 31

a) Preparation of a Phosphorus-Modified Epoxy Resin Based on Ethylenediethylphosphinic Acid

[0273] A four-neck flask equipped with reflux condenser, thermocouple, nitrogen inlet and stirrer is initially charged with 100 g of Beckopox® EP 140, EP value 180 g/mol. While stirring, the mixture is heated to 110° C. and residual water is removed under reduced pressure, followed by ventilation with dry nitrogen. Thereafter, the temperature in the flask is increased to 130° C., and 11.7 g of ethanebisethylphosphinic acid are added while stirring with nitrogen flow. The temperature of the reaction mixture is increased to 160° C. and maintained for 1 h. The product is subsequently poured out while hot and cooled. This gave a phosphorus-modified epoxy resin with a phosphorus content of 3% by weight and an epoxy equivalent of 267 g/mol.

[0274] The proportion of phosphorus in the epoxy resin was varied correspondingly by means of different amounts of ethanebisethylphosphinic acid prepared in accordance with the invention in the synthesis (examples 31 a) 1 to a) 4).

b) Preparation of a Phosphorus-Modified Epoxy Resin Based on DOPO-HQ (Comparative Example, 31 b))

[0275] A four-neck flask equipped with reflux condenser, thermocouple, nitrogen inlet and stirrer is initially charged with 100 g of Beckopox® EP 140, EP value 180 g/mol. While stirring, the mixture is heated to 110° C. and residual water is removed under reduced pressure, followed by ventilation with dry nitrogen. Thereafter, the temperature in the flask is increased to 130° C., and 19 g of DOPO-HQ are added while stirring with nitrogen flow. The temperature of the reaction mixture is increased to 160° C. and kept there for 2.5 h. The product is subsequently poured out while hot and cooled.

[0276] A phosphorus-modified epoxy resin with a phosphorus content of 1.5% by weight and an epoxy equivalent of 286 g/mol was obtained.

[0277] Table 1 shows the combination of the ethanebisethylphosphinic acid prepared in accordance with the invention with a bisphenol A novolac as a hardener and in an example with an additional flame retardant. The accelerator used was 2-phenylimidazole.

[0278] As can be inferred from table 1, at a concentration of in the P resin, a V-0 classification was attained both at thickness 3 mm and at 1.6 mm. The impact resistances of the polymer moldings produced with these formulations were always at a higher level compared to the reference example. In the water used for the hydrolysis, moreover, no phosphorus was found. Accordingly, the ethanebisethylphosphinic acid prepared in accordance with the invention is not hydrolyzed and is not then washed out of the thermoset network in the course of water storage.

[0279] This has the advantage that the phosphorus compound of the invention remains in the product, i.e. the polymer, and hence, advantageously, high product stability, longer-lasting material properties and also no “exudation” are achieved.

[0280] Example 32 (Comparative Example for Preparation of Ethylenebis(Ethylphosphinic Acid))

[0281] In a 1 L 5-neck flask equipped with gas inlet frit, thermometer, stirrer, reflux condenser and initiator metering system, a solution of 94.0 g of ethylphosphonous acid (prepared as in example 1) is dissolved in 200 g of glacial acetic acid and heated to about 90° C. While stirring, a solution of 11.4 g of sodium peroxodisulfate in 30 g of water is metered in over a period of 5 h. At the same time, through the gas inlet frit, about 10 L/h of acetylene are passed through the solution. In the course of this, the reaction temperature is kept at about 100° C. After the acetylene has been removed by passing nitrogen through, the mixture is left to cool, in the course of which ethylenebis(ethyl-phosphinic acid) precipitates out in the form of colorless crystals. The product contains, as well as ethylenebis(ethylphosphinic acid), also 7% ethylphosphonic acid as oxidative by-product as a result of the use of the free-radical peroxide initiator.

[0282] After washing with acetic acid, ethylenebis(ethylphosphinic acid) product is obtained in a yield of 86.7 g (81% of theory).

TABLE-US-00003 TABLE 1 Example 31 a) 1 a) 2 a) 3 a) 4 b) (C)* Resin P-modified 100 100 100 100 — formulation EP resin based on ethanebis(ethyl- phosphinic acid) P-modified — — — — 100 EP resin based on DOPO-HQ Phenol novolac 34 43 46 46 37 2-Phenylimidazole 0.03 0.03 0.03 0.03 0.03 Aluminum — — — 25 — trihydroxide (TS601) Properties P content in test 2.6 1.8 1.3 1.3 1.1 of the plaque [%] polymer Charpy impact 50 44 35 30 26 molding resistance [kJ/cm2] P content of water <1 <1 <1 <1 <1 after storage at 100° C. [ppm] UL 94 V0 V0 V1 V0 V0 *(C) = comparative example

[0283] The washed end product also still contains secondary components and impurities which are attributable to the free-radical initiator and still have to be removed. Secondary components of this kind are, for example, the decomposition products of the free-radical initiator, but also the solvent in which the free-radical initiator is dissolved. Accordingly, these by-products and decomposition products are also introduced into the polymer with the ethylenebis(ethylphosphinic acid) prepared only by free-radical means, and lead to higher instability of the polymer. Moreover, the handling of free-radical initiators in the laboratory and on the production scale is inconvenient and costly because of the high thermal instability in some cases.