Preparations having improved efficacy as flame retardants

Abstract

The present invention relates to preparations having improved efficacy as flame retardants, to the use thereof and to polyurethanes containing the preparations according to the invention.

Claims

1. A preparation comprising: i) a mixture comprising poly(alkylene phosphates) of formula (I) ##STR00004## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently of one another represent an n-butyl radical or a 2-methylpropyl radical, A represents a radical of formula —CHR.sup.5—CHR.sup.6—(O—CHR.sup.7—CHR.sup.8).sub.a—, in which a represents an integer from 1 to 5 and R.sup.5, R.sup.6, R.sup.7 and R.sup.8 independently of one another represent hydrogen or methyl, and n represents an integer from 0 to 100, with the proviso that the poly(alkylene phosphates) of formula (I) present in the mixture differ from one another at least in the number n of repeating units and the weighted average of the number of repeating units n of the poly(alkylene phosphates) of formula (I) is 1.10 to 4.00, and ii) at least one cyclic phosphonic ester of formula (II) ##STR00005## in which R.sup.9, R.sup.10 and R.sup.11 each independently of one another represent a straight-chain or branched C.sub.1- to C.sub.4-alkyl radical and m represents the number 0 or 1.

2. The preparation according to claim 1, wherein in the radical of formula —CHR.sup.5—CHR.sup.6—(O—CHR.sup.7—CHR.sup.8).sub.a—, a represents the number 1.

3. The preparation according to claim 1, wherein R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are all identical and represent hydrogen.

4. The preparation according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are all identical and represent n-butyl radicals.

5. The preparation according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are all identical and represent 2-methylpropyl radicals.

6. The preparation according to claim 1, wherein the weighted average of the number of repeating units n of the poly(alkylene phosphates) of formula (I) is in the range from 1.20 to 3.00.

7. The preparation according to claim 1, wherein the mixture comprising poly(alkylene phosphates) of formula (I) has a molar mass distribution as determined by gel permeation chromatography against polystyrene standards with tetrahydrofuran as the eluent, wherein in the molar mass distribution the area fraction of poly(alkylene phosphate) of formula (I) where n=1 is 10 to 70 area percent.

8. The preparation according to claim 1, wherein R.sup.9, R.sup.10 and R.sup.11 independently of one another represent methyl or ethyl.

9. The preparation according to claim 1, wherein R.sup.9 and R.sup.10 both represent methyl and R11 represents ethyl.

10. The preparation according to claim 1, wherein the preparation contains at least one cyclic phosphonic ester of formula (II) where m=0 and at least one cyclic phosphonic ester of formula (II) where m=1.

11. The preparation according to claim 1, wherein the preparation contains 60% to 99.9% by weight of the mixture comprising poly(alkylene phosphates) of formula (I) and 0.1% to 40% by weight of the at least one cyclic phosphonic ester of formula (II) based on the total preparation.

12. The preparation according to claim 11, wherein the preparation contains 70% to 99% by weight of the mixture comprising poly(alkylene phosphates) of formula (I) and 1% to 30% by weight of the at least one cyclic phosphonic ester of formula (II) based on the total preparation.

13. The preparation according to claim 1, wherein the preparation has a dynamic viscosity of 20 to 1000 mPa.Math.s at 23° C.

14. The preparation according to claim 1, further comprising one or more auxiliaries selected from the group consisting of solvents, antioxidants, stabilizers and dyes.

15. The preparation according to claim 1, further comprising one or more flame retardants distinct from the poly(alkylene phosphates) of formula (I) and from the at least one cyclic phosphonic ester of formula (II).

16. A process for producing polyurethanes, comprising reacting organic polyisocyanates with compounds having at least 2 isocyanate-reactive hydrogen atoms in the presence of the preparation according to claim 1 and in the presence of one or more blowing agents, stabilizers, and/or activators at 20° C. to 80° C.

17. A method of providing flame retardancy to a polyurethane, comprising preparing the polyurethane in the presence of the preparation according to claim 1.

Description

EXAMPLES

Synthesis Examples

General Synthesis Procedure for Mixtures Containing Poly(Alkylene Phosphates) of Formula (I) According to EP-A 3388479 (Synthesis Examples S1 to S5)

(1) A reactor fitted with a stirrer, dropping funnel, reflux cooler and vacuum apparatus was filled with the amount (parts by weight) of phosphorus oxychloride specified in table 1. The phosphorus oxychloride was temperature controlled to 10° C. to 20° C. Under a vacuum in the range from 500 to 700 mbar the amount of diethylene glycol specified in table 1 was added dropwise. On completion of the dropwise addition the pressure was reduced further to a final pressure of 5 to 15 mbar and the temperature raised to 20° C. to 30° C. A virtually colourless, liquid residue remained.

(2) In a further reactor fitted with a stirrer, dropping funnel and reflux cooler the amount of 2-methylpropanol/n-butanol specified in table 1 was initially charged at 20° C. to 30° C. and admixed with the residue obtained above. The mixture was subjected to further stirring at a temperature in the range from 20° C. to 30° C. until the reaction had abated and then neutralized by addition of aqueous sodium hydroxide solution. Two clear liquid phases were formed. These were separated and the organic phase was freed of excess reagent by distillation. The distillation residue was washed with water and finally residual water was removed by distillation. The mixtures remained as residue in the form of colourless liquids.

Synthesis Procedure for a Mixture Containing Poly(Alkylene Phosphates) According to EP-A 2 687 534 (Synthesis Example S6)

(3) A reactor fitted with a stirrer, dropping funnel, reflux cooler and vacuum apparatus was filled with the amount (parts by weight) of phosphorus oxychloride specified in table 1. The phosphorus oxychloride was temperature controlled to a temperature of 10° C. to 20° C. Under a vacuum in the range from 500 to 700 mbar the amount of diethylene glycol specified in table 1 was added dropwise. On completion of the dropwise addition the pressure was reduced further to a final pressure of 5 to 15 mbar and the temperature raised to 20° C. to 30° C. A virtually colourless, liquid residue remained.

(4) In a further reactor fitted with a stirrer, dropping funnel and reflux cooler the amount of ethanol specified in table 1 was initially charged at a temperature in the range from 20° C. to 30° C. and admixed with the residue obtained above. The mixture was subjected to further stirring at 20° C. to 30° C. until the reaction had abated and then neutralized by addition of concentrated aqueous sodium hydroxide solution. This was followed by addition of sufficient dichloromethane and water to form two clear liquid phases. These were separated and the organic phase was freed of dichloromethane, excess ethanol and water by distillation. The oligomer mixture remained as residue in the form of a colourless liquid.

(5) Determination of Weighted Average of the Number of Repeating Units n in the Mixtures S1 to S6

(6) The products produced in the synthesis examples 51 to S6 were revealed to be mixtures through analysis by gel permeation chromatography (GPC). The number-average molar masses M.sub.n of the mixtures were determined by GPC against polystyrene standards with tetrahydrofuran as the eluent in accordance with the method from DIN 55672-1:2007-08. The weighted average of the number of repeating units n of the poly(alkylene phosphates) of formula (I) present in the mixture was calculated from the measured number-average molar mass M.sub.n according to the following formula:
n=(M.sub.n−M.sub.E)/M.sub.R
where n: weighted average of the number of repeating units of the poly(alkylene phosphates) of formula (I) present in the mixture, M.sub.n: number-average molar mass in g/mol determined by gel permeation chromatography in accordance with the method from DIN 55672-1:2007-08, M.sub.E: sum of molar masses of end groups in g/mol and M.sub.R: molar mass of repeating unit in g/mol.

(7) For the mixtures 51 to S5 composed of poly(alkylene phosphates) of formula (I) where R.sup.1=R.sup.2=R.sup.3=R.sup.4=n-butyl or 2-methylpropyl and A=—CH.sub.2CH.sub.2OCH.sub.2CH.sub.2— where a=1, M.sub.E=266.31 g/mol and M.sub.R=224.19 g/mol. For the noninventive comparative substance S6 composed of poly(alkylene phosphates) of formula (I) where R.sup.1=R.sup.2=R.sup.3=R.sup.4=ethyl and A=CH.sub.2CH.sub.2OCH.sub.2CH.sub.2— where a=1, M.sub.E=182.16 g/mol and M.sub.R=194.14 g/mol. The results are shown in table 1.

(8) TABLE-US-00001 TABLE 1 Raw materials employed (parts by weight) for production of the mixtures (synthesis examples S1 to S5) and of comparative substance S6 and results of gel permeation chromatography Example S1 S2 S3 S4 S5 S6 Phosphorus 149.6 182.8 154.1 151.7 154.1 306.7 oxychloride Diethylene 74.0 68.3 62.7 66.3 62.7 118.7 glycol 2-Methyl- 380.0 500.0 444.7 360.0 propanol n-Butanol 444.7 Ethanol 618.2 Area fraction 27% 66% 53% 41% 51% 43% of dimer (i.e. n = 1) M.sub.n [g/mol] 844 608 656 709 649 462 n 2.58 1.53 1.74 1.97 1.71 1.44

(9) In addition to the synthesis products recited in table 1 production of the flame retardant preparations also employed the following substances: Fyrol® PNX Commercially available product from ICL-IP Bitterfeld GmbH, poly(alkylene phosphate) of formula (I) in which R1 to R4 represent ethyl radicals, A represents an ethylene radical, n represents a number between 2 and 20 and which does not contain any monomeric (i.e. n=0) or dimeric (i.e. n=1) constituents. Gel permeation chromatography under the abovementioned conditions indicated an area fraction of the dimer (i.e. n=1) of 2.4%, a number-average molar mass M.sub.n of 640 g/mol, and taking into account the values for M.sub.E=182.16 g/mol and M.sub.R=152.09 g/mol, thus a weighted average of the number of repeating units 1.7 of 3.01. Amgard® CU Commercially available product from Lanxess Deutschland GmbH, mixture of cyclic phosphonic esters of formula (II) where m=0 and m=1 and R9, R10=methyl and R11=ethyl.
Production of the Inventive Flame Retardant Preparations

(10) The components listed in table 2 were weighed in in the specified mass ratios and under a nitrogen atmosphere stirred with a mechanical stirrer at 300 rpm at 25° C.

(11) Viscosities of the Components and of the Flame Retardant Preparations

(12) The viscosities of the raw materials employed and the produced flame retardant preparations were determined at 23° C. with a commercially available falling ball viscometer and are listed in table 2.

(13) TABLE-US-00002 TABLE 2 Composition of flame retardant preparations and viscosities Mixture Amgard ® Viscosity Mixture (parts by CU (parts (mPa .Math. s/ Example (type) mass) by mass) 23° C.) V1 S1 100 0 315 V2 S2 100 0 79 V3 S3 100 0 97 V4 S4 100 0 138 V5 S5 100 0 93 V6 S6 100 0 58 V7 Fyrol ® PNX 100 0 1241 V8 none 0 100 302,270 B1 S1 75 25 968 B2 S2 75 25 298 B3 S3 75 25 350 B4 S4 75 25 462 V10 S6 75 25 350 V9 Fyrol ® PNX 75 25 3,473 B1-B4 = inventive examples
Evaluation of Results of Gel Permeation Chromatography and Viscosity Measurement

(14) The molar mass distribution of the for producing the mixtures 51 to S5 features a proportion of the dimer, i.e. of the poly(alkylene phosphate) of formula (I) where n=1, of 27% to 66%. By contrast, the comparative material Fyrol PNX contains only 2.4% of dimer.

(15) The viscosity of Amgard® CU (comparative example V8) of 302.270 mPas (23° C.) is of a magnitude such that handling and processing with the apparatus customary for producing polyurethanes encounters significant technical problems. The viscosities of the inventive flame retardant preparations B1 to B4 are all in the preferred range of 20 mPa.Math.s to 1000 mPa.Math.s (23° C.) and thus lower than the viscosity of Fyrol PNX (comparative example V7) and a flame retardant preparation composed of Fyrol PNX and Amgard CU (comparative example V9).

(16) The noninventive mixture S6 (see comparative example V6) and a mixture produced therefrom with Amgard® CU (see comparative example V10) feature acceptable viscosities. However, S6 causes elevated emissions in the foam (see below in table 4) and therefore has poor suitability for the purpose of the present invention.

(17) Production of Flexible Polyurethane Foams

(18) TABLE-US-00003 TABLE 3 Raw materials and usage amounts for producing flexible polyether polyurethane foams Parts by Component Function Description mass A Polyol Arcol ® 1105 (Covestro AG), 100 polyether polyol with OHN of 56 mg KOH/g B Blowing agent water 3.0 C Catalyst Addocat 108 ® (LANXESS 0.08 Deutschland GmbH), 70% solution of bis(2-dimethyl- aminoethyl)ether in dipropylene glycol D Catalyst Addocat ® SO (LANXESS 0.16 Deutschland GmbH), tin(II) 2-ethylhexanoate E Stabilizer Tegostab ® B 8232 (Evonik), 1.0 silicone stabilizer F1 Flame retardant Mixture V4 see table 4 F2 Flame retardant Mixture V6 see table 4 F3 Flame retardant Inventive flame retardant see table 4 preparations B4 G Diisocyanate Desmodur ® T 80 (Covestro AG), 40.9 tolylene diisocyanate, isomer mixture OHN = hydroxyl number according to DIN 53240
Production of Flexible Polyether Polyurethane Foams

(19) The raw materials for producing flexible polyether polyurethane foams and the usage amounts thereof are reported in table 3. The usage amounts of the flame retardants were varied systematically, see below. The raw materials with the exception of the diisocyanate (component G) were stirred together to afford a homogeneous mixture. The diisocyanate was then added and the mixture briefly subjected to vigorous stirring. After a cream time of 15-20 s and a full-rise time of 170-200 s a flexible polyether polyurethane foam having an envelope density of 33 kg/m.sup.3 was obtained. All experiments afforded uniformly fine-celled foams.

(20) Determination of Flame Retardancy

(21) The flexible polyurethane foams (polyether and polyester) were tested in accordance with the specifications of Federal Motor Vehicle Safety Standards FMVSS-302 and classified according to the flammability ratings SE (self-extinguishing), SE/NBR (self-extinguishing/no burn rate), SE/BR (self-extinguishing/with burn rate), BR (burn rate) and RB (rapid burn). The flammability tests were carried out five times for each formulation.

(22) In the absence of a flame retardant the flexible polyurethane foam burns rapidly (flammability rating RB). To determine the effectiveness of the flame retardants, formulations with increasing amounts of flame retardant (parts by mass per 100 parts of polyol component, php) were produced and tested. This was followed by determination of the lowest amount of flame retardant allowing the best flammability rating of SE to be achieved in each repetition. The lower this amount the greater the efficacy of the flame retardant. The results are shown in table 4.

(23) Determination of Emissions

(24) The flexible polyurethane foams (polyether and polyester) were tested for the release of volatile constituents according to the specifications of test method VDA 278. To determine the emissions of the VOC class the foam specimen is heat treated at 90° C. for 30 min. Determination of the emissions of the FOG class requires the same foam specimen to be heat treated at 120° C. for a further 60 min. The results are listed in table 4. Foam specimens containing the amounts of flame retardant reported in table 4 were analysed in each case.

(25) Determination of Fogging Condensate

(26) The fogging behaviour of the flexible polyurethane foams was analysed as per DIN 75201 B. The measured amounts of fogging condensate after storage at 100° C. for 16 hours are shown in table 4. Foam specimens containing the amounts of flame retardant reported in table 4 were analysed in each case.

(27) TABLE-US-00004 TABLE 4 Efficacy, emissions and fogging condensate for the flexible polyether polyurethane foams Efficacy (minimum VOC FOG amount for according according Fogging flammability to VDA to VDA condensate Example flame retardant rating SE in php) 278 (ppm) 278 (ppm) (mg) V4 Mixture S4 according 6 23 157 0.38 to EP-A 3388479 V6 Mixture S6 according 4 94 260 0.39 to EP-A 2 687 534 B4 Inventive flame 5 18 206 0.33 retardant preparation B4
Evaluation of Results for Flexible Polyether Polyurethane Foams

(28) The mixture S4 according to EP-A 3388479 alone (comparative example V4) shows the lowest efficacy but low emission and fogging values in the polyether foams. The mixture S6 known from EP-A 2 687 534 (comparative example V6) shows better efficacy but despite a lower usage amount causes markedly higher emissions in the VDA-278 test. The inventive flame retardant preparation B4 shows better efficacy than the mixture S4 present therein alone and shows low emissions and less fogging condensate and therefore exhibits the best profile of properties.

(29) TABLE-US-00005 TABLE 5 Raw materials and usage amounts for producing flexible polyester polyurethane foams Parts by Component Function Description mass A Polyol Desmophen ® 2200 B (Covestro AG), 100 polyester polyol with OHN of 60 mg KOH/g B Blowing agent water 4.0 C Catalyst Niax ® A-30 (Momentive), 0.25 bis(2-dimethylaminoethyl) ether D Catalyst Addocat ® 117 (LANXESS Deutschland 0.25 GmbH), tertiary amine E Stabilizer Tegostab ® B 8324 (Evonik), silicone 1.0 stabilizer F1 Flame retardant Fyrol ® PNX see table 6 F2 Flame retardant Flame retardant preparation V9 see table 6 F3 Flame retardant Mixture V4 see table 6 F5 Flame retardant Inventive flame retardant preparations B4 see table 6 G Diisocyanate Desmodur ® T 80 (Covestro AG), 24.1 tolylene diisocyanate, isomer mixture H Diisocyanate Desmodur ® T 65 (Covestro AG), 24.1 tolylene diisocyanate, isomer mixture OHN = hydroxyl number according to DIN 53240
Production of Flexible Polyester Polyurethane Foams

(30) The raw materials for producing flexible polyester polyurethane foams and the usage amounts thereof are reported in table 5. The usage amounts of the flame retardants were varied systematically, see above. The raw materials with the exception of the two diisocyanates (components G and H) were stirred together to form a homogeneous mixture. The two premixed diisocyanates were then added and the mixture briefly subjected to intensive stirring. After a cream time of 10-15 s and a full-rise time of 70-80 s a flexible polyester polyurethane foam having an envelope density of 29 kg/m.sup.3 was obtained. The foam structure of the flexible polyester polyurethane foams depended on the flame retardants used. Said structure is reported in table 6 as “uniformly fine-celled” (“uf”) or “nonuniformly coarse-celled” (“nc”). A comparative foam without flame retardant had a uniformly fine-celled foam structure and burned rapidly (flammability rating RB).

(31) TABLE-US-00006 TABLE 6 Foam structure and efficacy of the flexible polyester polyurethane foams Efficacy Efficacy (minimum (minimum amount for amount for flammability flammability Example Flame retardant Foam structure rating BR in php) rating SE in php) V4 Mixture S4 according uf 5 7 to EP-A 3388479 B4 Inventive flame uf 4 7 retardant preparation B4 V7 Fyrol ® PNX nc — — Flame retardant V9 preparation V9 nc — —
Evaluation of Results for Flexible Polyester Polyurethane Foams

(32) The comparative examples V7 and V9 show that flame retardants based on Fyrol® PNX are not suitable for the production of flame retardant polyester polyurethane foams. The produced foams had a nonuniformly coarse-celled foam structure and were unusable.

(33) By contrast, the mixture S4 according to EP-A 3388479 (comparative example V4) makes it possible to produce the desired uniformly fine-celled foam structure. However the flame retardancy is worse than for the mixture S6 according to EP-A 2 687 534 (comparative example V6). The inventive flame retardant preparation B4 likewise shows good compatibility with the polyester polyol and exhibits a slightly improved efficacy compared to the mixture S4.