FLEXIBLE FOAM WITH HALOGEN-FREE FLAME RETARDANT

Abstract

The invention relates to flame-retardant flexible polyurethane foams with phosphazene and to methods for producing PUR flexible foams by reacting a component A containing: A1, an isocyanate-reactive component, A2, a propellant containing water, A3, optionally auxiliary agents and additives, and A4, a flame retardant, with B, an isocyanate component. The invention is characterized in that the flame retardant A4 contains a phosphazene according to the formula (I): [P.sub.mN.sub.mX.sub.k] (I), where X independently of one another represents O-aryl or NR-aryl, at least one aryl group is substituted, X can represent a bridge, R is selected from the group of H, C1-C4 alkyl, and aryl, and m represents a number from 1 to 5, particularly preferably 3 or 4, k depends on m and represents a number from 0 to 2m, and the phosphazene does not have any groups which are reactive towards isocyanates.

Claims

1. A process for producing open-celled flexible PUR foams comprising reacting a component A which comprises A1 an isocyanate-reactive component, A2 a blowing agent comprising water, A3 optionally auxiliary and/or additive substances, A4 a flame retardant with B an isocyanate component, wherein the flame retardant A4 comprises a phosphazene corresponding to formula (I)
[P.sub.mN.sub.mX.sub.k](I), wherein each X independently of one another represents O-aryl or NR-aryl and on average over all phosphazenes at least 10% of the aryl groups are substituted, wherein X may represent a bridge, wherein: R represents a H atom, a C1-C4 alkyl group, or an aryl group, and m represents a number from 1 to 5, k is dependent on m and represents a number from 0 to 2m with the proviso that the phosphazene is free of isocyanate-reactive groups.

2. The process as claimed in claim 1, wherein the isocyanate-reactive component A1 comprises a polyether polyol having a hydroxyl number of 25 mg KOH/g to 2000 mg KOH/g.

3. The process as claimed in claim 1, wherein the isocyanate-reactive component A1 comprises a PHD polyol.

4. The process as claimed in claim 1, wherein the blowing agent A2 additionally comprises at least one compound comprising at least one of a halogen-free chemical blowing agent, a -halogen-free physical blowing agent, and a (hydro)fluorinated olefin.

5. The process as claimed in claim 1, wherein the flame retardant A4 is free of components having isocyanate-reactive groups.

6. The process as claimed in claim 1, wherein the flame retardant A4 comprises 50% by weight to 100% by weight, based on the total mass of the flame retardant A4, of the phosphazene corresponding to formula (I).

7. The process as claimed in claim 1, wherein the content of phosphazene corresponding to formula (I) is 0.5% by weight to 40.0% by weight based on 100% of the combined weight of A1, A2, A3 and A4.

8. The process as claimed in claim 1, wherein the flame retardant A4 additionally comprises at least one compound comprising at least one of a halogen-free phosphate and a halogen-free phosphonate.

9. The process as claimed in claim 1, wherein the aryl group of O-aryl or NR-aryl of the substituent X is substituted with at least one of a CN group, a C.sub.1-C.sub.4 alkyl group, a nitro group, a sulfonate group, a carboxylate group, and a phosphonate group.

10. The process as claimed in claim 1, wherein the phosphazene comprises a cyclic phosphazene

11. The process as claimed in claim 1, wherein component A comprises A1 39.50% to 99.28% by weight (based on 100% of the combined weight of components A1, A2, A3 and A4) of a polyether polyol or a mixture of polyether polyols, having an average equivalent weight of 0.8 to 2.2 kg/mol and an average functionality of 1.8 to 6.2, A2 0.2% to 20.0% by weight (based on 100% of the combined weight of components A1, A2, A3 and A4) of water, A3 0.02% to 3.02% by weight (based on 100% of the combined weight of components A1, A2, A3 and A4) of at least one catalyst comprising an aliphatic amine, and up to 30% by weight (based on 100% of the combined weight of components A1, A2, A3 and A4) of fillers that are stably dispersed in A1 and not isocyanate reactive, A4 0.5% to 8.0% by weight (based on 100% of the combined weight of components A1, A2, A3 and A4) of flame retardant.

12. The process as claimed in claim 1, where component B comprises 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanate, polyisocyanates which comprise carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups and derive from 2,4- and/or 2,6-tolylene diisocyanate or from 4,4- and/or 2,4- and/or 2,2-diphenylmethane diisocyanate, or combinations thereof.

13. The process as claimed in any of claim 1, wherein component B comprises 60% to 100% by weight of difunctional isocyanates, based on 100% by weight of component B.

14. A flexible PUR foam obtainable by the process as claimed in claim 1, wherein the apparent density of the flexible PUR foam is between 10 kg/m.sup.3 and 20 kg/m.sup.3, or between 35 kg/m.sup.3 and 80 kg/m.sup.3 and the isocyanate index is between 60 and 110, or between 200 kg/m.sup.3 and 300 kg/m.sup.3 and the isocyanate index is between 75 and 120.

15. An article comprising the flexible PUR foam as claimed in claim 14, in furniture cushions, textile inserts, bedding, automotive sponges, and/or construction industries.

16. The process as claimed in claim 9, wherein the aryl group of O-aryl is substituted with at least one of a CN group, a COOR group, and a C.sub.1-C.sub.4 alkyl group.

17. The process as claimed in claim 9, wherein the aryl group of NR-aryl is substituted with at least one C.sub.1-C.sub.4 alkyl group.

18. The process as claimed in claim 10, wherein the cyclic phosphazene has a structure corresponding to one of the general formulae (III) to (VI) ##STR00003## wherein each X independently of one another represents O-aryl or NR-aryl, in which each aryl independently represents a substituted aryl radical, and R represents a H atom, a C.sub.1-C.sub.4 alkyl group, or an aryl group.

Description

EXAMPLES

[0152] The present invention is elucidated further by the examples which follow, but without being restricted thereto.

TABLE-US-00001 A1-1 glycerol-started polyalkylene oxide having a molecular weight of 4800 g/mol, employed as suspension with A3-1 A2-1 25% by weight urea in water A3-1 reaction product of tolylene diisocyanate (TDI) and hydrazine hydrate employed as suspension with A1-1 A3-2 mixture of Jeffcat ZF-10 (Huntsman) and Dabco NE1070 Air Products) in a weight ratio of 1:20 A3-3 Tegostab B 8738 LF2, polyetherdimethylsiloxane (Evonik) A4-1 Rabitle FP 200, cyclic phosphazene with phenoxy and methoxy substituents (Fushimi Pharmaceuticals, halogen-free) A4-2 Rabitle FP 300-B, cyclic phosphazene with cyanophenoxy substituents (Fushimi Pharmaceuticals, halogen-free) A4-3 Rabitle FP 366, cyclic phosphazene with propoxy substituents (Fushimi Pharmaceuticals, halogen-free) A4-4 Rabitle FP 390, cyclic phosphazene with tolyloxy and phenoxy substituents (Fushimi Pharmaceuticals, halogen-free) A4-5 trischloropropyl phosphate, halogenated flame retardant A4-6 melamine, halogen-free solid flame retardant insoluble in all other components A4-7 NCO-reactive reaction product of 60 g of A4-2 and 8 dm.sup.3 of hydrogen in 0.42 dm.sup.3 of THF at 10 bar over Pd/C as catalyst. The amine number of 66.45 mg KOH/g results in an equivalent weight of 884 g/mol CH.sub.2NH.sub.2. .sup.31P-NMR (400 MHz, CDCl.sub.3): 8.01 and 7.94 ppm vs. H.sub.3PO.sub.4 (for comparison A4-2: 7.49, 7.54 ppm). Complete disappearance of the doublets at 7.50 ppm and 7.40 ppm in the .sup.1H-NMR (400 MHz, CDCl.sub.3) indicates complete hydrogenation of the nitrile groups in A4-2. The signal of the CH.sub.2NH.sub.2 group appears in the .sup.1H-NMR at 3.70 ppm vs. TMS. ASAP-MS: m/z 694 (10%, M + H.sup.+, C.sub.36H.sub.30N.sub.3O.sub.6P.sub.3, CAS 1184- 10-7), m/z 708 (10%, M + H.sup.+, C.sub.37H.sub.32N.sub.3O.sub.6P.sub.3), m/z 723 (60%, M + H.sup.+, C.sub.37H.sub.33N.sub.4O.sub.6P.sub.3, CAS 81525-08-8), m/z 737 (100%, M + H.sup.+, C.sub.37H.sub.35N.sub.5O.sub.6P.sub.3), m/z 752 (40%, M + H.sup.+, C.sub.38H.sub.36N.sub.5O.sub.6P.sub.3). C.sub.37H.sub.33N.sub.4O.sub.6P.sub.3, CAS 81525-08-8, contains one aminomethyl group. C.sub.38H.sub.36N.sub.5O.sub.6P.sub.3 contains two aminomethyl groups. Both are thus suitable for reaction with isocyanate B-1 Desmodur 44V20L, isocyanate comprising 31.5% by weight of NCO groups and having a viscosity of 0.2 Pa * s at 298K (Covestro) B-2 Desmodur T80, isocyanate comprising 48% by weight of NCO groups, mixture of 80% by weight of 2,4-TDI and 20% by weight of 2,6-TDI (Covestro)

Production and Testing of Flexible PUR Foams

[0153] The fire test is based on British standard BS 5852:1990-part 2 with ignition source 4 (Crib) but was performed without a textile covering layer.

[0154] Measurement of apparent density was performed according to DIN EN ISO 845 (October 2009).

[0155] The compressive strength and damping of the flexible PUR foam were measured according to DIN EN ISO 3386-1 (September 2010).

[0156] To produce the flexible PUR foams the required amount of component A was initially charged into a cardboard beaker having a sheet metal bottom (volume: about 850 ml) and loaded with air using a stirring means (Pendraulik) fitted with a standard stirring disk (d=64 mm) at 4200 rpm for 45 seconds. The component B was then added to the component A and the mixture was subjected to intensive mixing with a stirring means for 5 seconds. The precise composition of the individual components is summarized in table 1. To determine the characteristic reaction times a stopwatch was started at commencement of mixing. About 93 g of the reaction mixture were subsequently poured into a Teflon film-lined aluminum box mold having a volume of 1.6 dm.sup.3 and a temperature of 23 C. The mold was closed and bolted shut for 6 minutes. The mechanical and flame retardancy tests were determined on the molded foam and the reaction kinetics were determined on the freely foaming reaction mixture in the beaker.

[0157] The cream time t.sub.C has been reached when an expanding of the mixture is observed (commencement of the reaction of isocyanate and water). The fiber time t.sub.G determines the time at which dabbing a wooden rod on the surface of the rising flexible PUR foam results in fibers being drawn. The full rise time i.sub.S has been reached when the expansion of the flexible PUR foam has finally ceased. It should be noted here that some systems have a propensity to undergo some sagging before rising again.

[0158] It is apparent from table 1, kinetics and mechanical properties part that examples 2 to 5 comprising phosphazenes as flame retardants have similar apparent core densities (AD) to examples 1 and 6 without flame retardants and with TCPP as the flame retardant. The flexible PUR foam from example 7 with melamine as the flame retardant has an elevated apparent density in contrast to the other flexible PUR foams. The plasticizing effect is however not as pronounced as for TCPP. The effect of the flame retardants from example 2 to 6 as plasticizers, which makes them particularly suitable for flexible PUR foams, is also apparent. Example 1 and especially example 7 show a marked hardening of the flexible PUR foam. The damping of the flexible PUR foams of examples 3-5 is superior in comparison to the flexible PUR foams without flame retardants, with TCPP and with melamine.

[0159] The behavior of the flexible PUR foams in the fire test is shown in table 1 in the fire test behavior part. The molar fractions of the employed flame retardant A4 in examples 2 to 7 are used to assess the efficiency of the flame retardant: The greater this difference the faster the flame is extinguished and the more efficient is the flame retardant.

[0160] It is apparent that the examples 2 and 4 in which phosphazenes not having the inventive formula (I) were used as flame retardants do not result in self-extinguishing flexible PUR foams. It is moreover apparent that example 7 which was produced with a flame retardant that is not low melting or liquid results in identical fire behavior to example 1. A particularly marked shortening of the time until self-extinguishing per mmol of employed flame retardant A4 is shown especially by example 3. The flame retardant in example 5 is just as efficient or slightly more efficient than the flame retardant in example 6, wherein example 6 contains a halogenated flame retardant and accordingly has disadvantages such as for example corrosive hydrochloric acid in smoke gases.

TABLE-US-00002 TABLE 1 Composition of the reaction mixtures 1 2 3 4 5 6 7 8 .sup.1) Comparative Comparative Inventive Comparative Inventive Comparative Comparative Comparative A1-1 % by weight 80.75 77.65 77.65 77.65 77.65 77.65 77.65 77.65 A2-1 % by weight 3.3 3.17 3.17 3.17 3.17 3.17 3.17 3.17 A3-1 % by weight 14.25 13.5 13.5 13.5 13.5 13.5 13.5 13.5 A3-2 % by weight 1.05 1 1 1 1 1 1 1 A3-3 % by weight 0.65 0.63 0.63 0.63 0.63 0.63 0.63 0.63 Flame retardant A4-1 % by weight 4.2 A4-2 % by weight 4.2 A4-3 % by weight 4.2 A4-4 % by weight 4.2 A4-5 % by weight 4.2 A4-6 % by weight 4.2 A4-7 % by weight 4.2 Isocyanate .sup.2) B1 g/100 g A 8.8 8.8 8.8 8.8 8.8 8.8 8.8 8.8 B2 g/100 g A 20.4 20.4 20.4 20.4 20.4 20.4 20.4 20.4 Index 85 85 85 85 85 85 85 85 .sup.1) the reported % by weight relates to the sum of the components A1 to A4 = 100% by weight. .sup.2) the content of molecules having two NCO groups per molecule based on the sum of B1 and B2 is 83% by weight in all cases (continued, kinetics and mechanical properties) Cream time t.sub.c s 5 6 4 6 6 5 5 5 Fiber time t.sub.G s 45 67 47 75 75 55 60 55 Full rise time t.sub.s s 90 10 87 112 126 105 105 93 Apparent density (AD) kg/m.sup.3 44 44 46 46 46 45 49 n.s. from core of molding Compressive strength kPa 3.7 2.9 3.1 3.2 3.0 2.6 5.0 n.s. (CV40) at 40% compression Damping 24% 23% 22% 22% 22% 24% 26% n.s. CV40/AD m.sup.2/s.sup.2 86 66 67 71 65 58 102 n.s. n.s.: The mechanical data for comparative test 8 could not be specified. (continued, fire test behavior) Proportion of mmol/ 0 99 58 105 64 127 350 58 flame retardant kg (A4) based on the sum of m(A1 to A4).sup.2) Melting point of C. <20 72 <20 <20 52 350 (decom- <20 flame retardant position) t.sub.SE .sup.3) s 87 >95 68 >95 83 81 87 91 t.sub.SE .sup.4) s 0 Not self- 19 Not self- 4 6 0 4 extinguishing extinguishing t.sub.SE per mmol of s/mmol 0.35 0.06 0.05 0 0.07 flame retardant .sup.5) .sup.2)proportion of the amount of substance (in mmol) of the flame retardant A4 used in the particular test per the sum of the masses (in kg) of the employed components A1 to A4. .sup.3) t.sub.SE: Time measured until self-extinguishing t.sub.SE) of flexible PUR foam. .sup.4) t.sub.SE: The difference between the time t.sub.SE and the corresponding time measured for the reference sample without flame retardant is reported in seconds. .sup.5) t.sub.SE per mmol of flame retardant: t.sub.SE based on the amount of substance (in mmol) of the flame retardant A4 employed in the particular test.