WO2008100316A1

WO2008100316A1 - Phosphate-containing flame retardants

Info

Publication number: WO2008100316A1
Application number: PCT/US2007/062285
Authority: WO
Inventors: Arthur G. Mack; Zheng Chai
Original assignee: Albemarle Corporation
Priority date: 2007-02-16
Filing date: 2007-02-16
Publication date: 2008-08-21
Also published as: TW200837111A

Abstract

The present invention relates to flame retardant compositions that are suitable for use in polyurethane foam formulations.

Description

PHOSPHATE-CONTAINING FLAME RETARPANTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to United States Provisional Application No.

60/750,925 and United States Provisional Application No. 60/750,924, both filed December

16, 2005, which are both hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to flame retardant compositions. More particularly the present invention relates to phosphate-containing flame retardant compositions that are suitable for use in polyurethane foam formulations.

BACKGROUND OF THE INVENTION

[0003] Tris(dichloropropyl) phosphate ("TDCP") is an effective halogenated flame retardant that is commonly used to provide flame retardancy in a wide range of materials especially polyurethanes, etc. However, TDCP has properties that can make it unsuitable for certain applications such as thermoplastic processing. Thus, there is a need for an alternative to

TDCP.

THE INVENTION

[0004] The present invention relates to a class of flame retardant compositions characterized by the general formula:

wherein Z is selected from:

A) or

[*^/] M

wherein if Z is A), X₁, X₂, X₄, and X₅ are each independently selected from:

and Y is selected from:

; and wherein if Z is B), X₁, X₂, and X₃, are selected from: I, II, III, IV, V, VI, VII,

[0005] In some embodiments, Z is A), and in other embodiments Z is B). [0006] When Z is A), in one embodiment, Y is selected from / or H, and X₁, X₂, X₄, and X5 are selected from I or II. In other embodiments Y is selected from Hi or zv and Xi, X₂, X₄, and X₅ are independently selected from I, II, III, IV, V, VI, and VII, as described above. In some exemplary embodiments, when Z is A) and Y is selected from Hi or iv, the flame retardant compositions of the present invention are characterized by one of the formulas:

[0007] In some embodiments when Z is B), X₁, X₂, and X₃ are each independently selected from IX and X. In some embodiments, Xi, X₂, and X₃ are each IX or X. In another embodiment, two of Xi, X₂, and X₃ are selected from IX or X₅ and one of Xi, X₂, and X₃ is selected from I₅ II, III, IV, V₅ VI, VII, and VIII. In another embodiment, two of X₁, X₂, and X₃ are selected from IX or X, and one of Xi, X₂, and X₃ is selected from I, II, III, IV, V, VI, and VII. In yet another embodiment, two of Xi, X₂, and X₃ are IX or X, and one of Xi, X₂, and X₃ is II or VIII, is an exemplary embodiment II. [0008] The flame retardant compositions of the present invention can be formed by reacting a raw material having the general structure:

with at least one reactant, in some embodiments only one, selected from propylene oxide, epichlorobromine, epichlorhydrin, styrene oxide, propylene oxide, and epichlorobromine in the presence of a catalyst. The at least one reactant is readily selectable by one having ordinary skill in the art and knowledge of the desired flame retardant composition. [0009] The reaction of the raw material and at least one reactant in the presence of the catalyst can be achieved by solubilizing the raw material in a suitable solvent thus forming a reaction solution. In some embodiments, the solvent is selected from bromochloromethane ("BCM"), dibromomethane, toluene, xylene, mesiethylene, chlorobenzene, ethylendichloride ("EDC"), tetrachloroethlyne, chloroform, and the like. In some embodiments, the solvent is BCM.

[0010] After the reaction solution is formed, the catalyst and at least one reactant is added to the reaction solution, in some embodiments under constant stirring, thereby forming a reaction mass. The catalyst is typically added to the reaction solution in an amount in the range of from about 0.1 to about 1 mole%, based on the raw material. In some embodiments, the catalyst is added in an amount in the range of from about 0.1 to about 0.5 mole%, on the same basis. The at least one reactant is typically added to the reaction solution in an amount in the range of from about 3 to about 6 molar equivalences, based on the raw material, in some embodiments in the range of from about 3 to about 5 molar equivalences, on the same basis, and in some embodiments in the range of from about 3.5 to about 4.5 molar equivalences, on the same basis. In some embodiments, a molar excess of the at least one reactant can also be added to ensure complete conversion of the raw material to the flame retardant composition of the present invention.

[0011] The catalyzed reaction between the raw material and the at least one reactant is an exothermic reaction, and the temperature of the reaction mass is maintained in the range of from about 50 and about 9O⁰C during this reaction. In some embodiments, the temperature of the reaction mass is maintained in the range of from about 50 and about 8O⁰C, in some embodiments in the range of from about 60 and to about 8O⁰C, during the exothermic reaction. The temperature of the reaction mass can be maintained by any means known in the art such as by the use of cooling devices such as heat exchangers, etc. However, in some embodiments, the temperature of the reaction mass can be maintained through the controlled addition of the at least one reactant. For example, the temperature of the reaction mass can be monitored during the addition of the at least one reactant, and as the temperature increases, the addition rate slowed, and vice versa.

[0012] The catalyzed reaction between the raw material and the at least one reactant is allowed to continue until excess of the at least one reactant appears in the reaction mass, thus indicating the cessation of the exothermic reaction and thus the formation of a product mass. The amount of the at least one reactant in the reaction mass can be measured by any suitable means known but is conveniently measured by H and/or P NMR.

[0013] After the exothermic reaction is complete, the flame retardant composition according to the present invention can be recovered from the product mass. It should be noted that the product mass typically comprises an organic layer comprising the flame retardant composition and an aqueous layer. The method by which the flame retardant composition is recovered is not critical to the instant invention, and the recovery method can be selected from any known in the art. However, it should be noted that the organic layer and aqueous layer are typically present as an emulsion, and thus, in some embodiments, the recovery method used takes this into consideration. In one embodiment the method by which the flame retardant composition is recovered comprises first allowing the product mass to cool to room temperature, and then washing the cooled product mass with a first solution comprising a suitable base, such as Na₂CO₃ or NaOH, in some embodiments NaOH. The first solution typically comprises in the range of from about 10 to about 20wt.%, based on the first solution, of the base, in some embodiments in the range of from about 12 to about 16wt.%, on the same basis. After washing with the first solution, the product mass is washed with a second solution selected from those solutions known to be effective at separating an emulsion comprising an oily organic layer and an aqueous layer into these respective layers. Non- limiting examples of suitable solutions include a sand/water solution and a solution comprising an alkali earth metal salt. In one embodiment, the second solution is a saturated NaCl solution. By saturated NaCl solution, it is meant a solution comprising greater than about 20wt.% NaCl, based on the second solution, sometimes greater than about 30wt.%, on the same basis. [0014] The washing of the product mass with the first and second solutions typically lowers the pH of the aqueous layer to a pH within the range of from about 7.5 to about 9.5, in some embodiments within the range of from 7.5 to about 8.5. It should be noted that a small amount of a solvent, preferably selected from those suitable for use in solubilizing the raw material, can also be added during the washing to aid in phase separation. [0015] After washing with the first and second solutions, the organic phase can be recovered from the product mass. The method by which the organic phase is recovered is not critical to the present invention and can be selected from any method known to be effective at recovering an organic phase from an organic phase/aqueous phase mixture/solution. The flame retardant composition according to the present invention can be isolated from the organic phase by removing any remaining solvent through, for example, vacuum distillation and/or atmospheric distillation, and removing any remaining water through, for example, drying with an alkali metal salt such as NaCl. The recovered flame retardant composition is as described above, and is typically a nearly colorless liquid having the properties described below.

[0016] The inventors hereof have discovered that the flame retardant compositions of the present invention are characterized as having specific properties. These characteristics make them effective substitutes for Tris(dichloropropyl) phosphate ("TDCP"). These properties include at least one of, in some embodiments at least two of, in some embodiments all of: a) an acid number of less than about 0.3, in some embodiments less than about 0.1 as determined by titration with KOH; b) a hydrolytic stability consistent with the hydrolytic stability of TDCP; c) a 10% weight loss at in the range of about 250 to about 300⁰C, as determined by thermogravimetric analysis conducted under conditions including a temperature ramp of 10°C/minute up to 500⁰C in air; d) an APHA color index of less than 100, e) do not discolor polyurethane foams, i.e. have a yellowness index ("YI") within the range of about 1 to about 50% of the same polyurethane foam not containing a flame retardant composition according to the present invention.

[0017] As stated above, the flame retardant compositions of the present invention are suitable for use as an effective replacement for TDCP. Thus, the flame retardant compositions of the present invention can be used to impart flame retardancy to polyurethane flexible foams. In this embodiment, the present invention relates to a polyurethane foam formulation comprising a polyurethane foam and a flame retarding amount of a flame retardant composition according to the present invention. By a flame retarding amount, it is meant that the polyurethane foam formulation contains in the range of from about 1 to about 25wt.%, based on the polyurethane foam formulation, of the flame retardant composition, in some embodiments in the range of from about 5 to about 15 wt.%, on the same basis, and in some embodiments in the range of from about 5 to about 10 wt.%, on the same basis. Polyurethane foams suitable for use herein include any polyurethane foam known in the art. In some embodiments, the polyurethane foam is a flexible polyurethane foam. [0018] The above description is directed to several embodiments of the present invention. Those skilled in the art will recognize that other embodiments, which are equally effective, could be devised for carrying out the spirit of this invention. It should also be noted that preferred embodiments of the present invention contemplate that all ranges discussed herein include ranges from any lower amount to any higher amount.

[0019] The following examples will illustrate the present invention, but are not meant to be limiting in any manner.

EXAMPLES EXAMPLE 1

[0020] In this example, the materials described in Table 1 were used to produce a flame retardant composition according to the present invention. The flame retardant, referred to herein as Composition A, was formed by the following reaction scheme:

0)

[0021] The materials used to produce Composition A and their amounts are outlined in Table 1, below. It should be noted that the amounts described in Table 1 are not repeated throughout this example, but it should be understood that when this example states that a material was added, it was added in the amounts described therein. Table 1

[0022] The Resorcinol (99%), phosphorous oxychloride (99%), titanium «-butoxide (TnBT, 97%) and epichlorohyrin (99%) were purchased from Aldrich. BCM (98%) was purchased from Alfa Aesar. AU chemicals were used as received.

[0023] Step (1) of the reaction scheme outlined above was used to make the raw material used in producing flame retardant compositions according to the present invention, and thus, were used in making Composition A herein. Step (1) was conducted by adding to a dry 2000 mL 4-neck round bottom flask fitted with a mechanical stirrer, a thermal couple, and a reflux condensor attached to a scrubber, POCl₃ followed by MgCl₂. The mixture was heated to 76°C. Resorcinol was added to the mixture with vigorous stirring in 30 equi-portions over a 140-minute period. The contents of the flask were then heated to 78⁰C and held there for about 10 minutes, and then the temperature was raised to 85 ⁰C. The contents of the flask were heated at this temperature for 60 minutes, when HCl stopped bubbling through the contents the flask. The contents of the flask were cooled to room temperature and allowed to stand overnight under N₂.

[0024] After standing overnight, POCI₃ was stripped from the contents of the flask by performing an initial vacuum stripping step. The contents of the flask were heated to in the range of from about 64°C to about 91⁰C while the pressure of the flask was reduced to in the range of from about 130 to about 22 mmHg during the stripping. This initial stripping took about 40 minutes. The contents of the flask were then stripped again to remove an additional amount of POCl₃ in a final stripping conducted under conditions that included temperatures of 95°C and pressures of 25 mmHg. The second stripping continued for 90 minutes wnen bubbling stopped. A total of 604 grams of POCI₃ was recovered in this final stripping step. The raw material recovered weighed 653 gram and had a light yellow color. [0025] Step (2) of the reaction scheme outlined above was conducted by placing the reaction product (raw material) from step (1) in a dry 2000 mL 4-neck round bottom flask fitted with a mechanical stirrer, a thermocouple, an addition funnel, and a reflux condensor attached with a CaSO₄ drying tube. To the flask was added BCM at room temperature to obtain a clear solution that appeared non-viscous. Titanium n-butoxide was then added to the flask via a syringe to the solution to give a yellow color. With vigorous stirring, epichlorohydrin was added to the solution from the addition funnel in an above-surface, dropwise manner. The addition rate of the epichlorohydrin was such that temperature of the flask contents rose to 68⁰C in about 30 minutes when BCM was noticed to start refluxing. The addition of the epichlorohydrin was stopped to allow the temperature to decrease to 6O⁰C, and when this temperature was reached the epichlorohydrin additions resumed in the same manner. During the addition of the epichlorohydrin, the addition rate was adjusted constantly to keep the temperature of the flask contents in the range of from 60 to 7O⁰C. It should be noted that when the last portion (about 30 mL) of a total of 4.0 equivalences of epichlorohydrin was added, the temperature of the flask contents no longer "bounced" back up. After the last of the epichlorohydrin was added, an excess amount (10% of the amount outlined in Table 1) was added to ensure that the reaction was complete. H and P NMR were conducted on the contents of the flask, and the presence of excess epichlorohydrin was observed, indicating the completion of the exothermic reaction and thus the formation of the Compound A flame retardant composition. The contents of the flask were then allowed to cool to room temperature, and it was observed that the color of the flask contents turned from light yellow to yellow. The total reaction time for step (2) was 7 hours.

[0026] The product mass in the flask was observed to comprise an organic layer and an aqueous layer in an emulsion, and this product mass was washed with a 15% Na₂COs solution (500 mL x 2) followed by saturated NaCl (30wt% NaCl, based on the solution) (500 mL x 4) solution until the pH of the aqueous layer reached about 8. The yellow color of the product mass immediately disappeared with the addition of the Na₂CO3 solution It should be noted that about 100ml of BCM was added during the washing to help phase separation between the organic and aqueous layers. The organic layer was separated from the aqueous layer by removing the aqueous layer via vacuum and filtered through a fiberglass plug. BCM was then removed from the organic phase by vacuum distillation, and the organic phase was further dried by heating it to 70⁰C under 20 mm Hg for 1.5 hours with magnetic stirring, followed by rotary evaporation at 7O⁰C with a vacuum pump for 1.5 hours when there was no more BCM bubbling out. The flame retardant composition thus obtained was a near- colorless viscous material that weighed 1362 grams (yield 94%), and was observed, by H and P NMR, to have the structure of Composition A detailed in the reaction scheme above. [0027] Composition A was also analyzed by Thermogravimetric Analysis ("TGA"), for the presence of halogens (H and P NMR), for the acid number, color, and viscosity. The results of these measurements are indicated in Table 2 below.

EXAMPLE 2

[0028] In this example, the materials described in Table 3 were used in the amounts described in Table 3 to produce a flame retardant composition according to the present invention. It should be noted that the amounts described in Table 3 are not repeated through this example, but it should be understood that when this example states that a material was added, it was added in the amounts described therein. The raw material used was produced as discussed above in Example 1 and is referred to in this example as Composition B. The flame retardant, referred to herein as Composition C, was formed by the following reaction scheme:

Table 3

[0029] In this Example, titanium fert-butoxide (97%) and epichlorohyrin (99%) were purchased from Aldrich, and the BCM (98%) was purchased from Alfa Aesar. All chemicals were used as received.

[0030] Composition B was placed in a dry 2000 mL 4-neck round bottom flask, prepared as discussed above in Example 1, fitted with a mechanical stirrer, a thermocouple, an addition funnel, a nitrogen inlet, and a reflux condensor attached with a CaSO₄ drying tube. After placing Compound B in the flask, BCM was added to the flask at room temperature to obtain a clear solution that appeared non-viscous. Titanium fert-butoxide was added via a syringe to the flask, and the contents of the flask turned a light yellow color. With vigorous stirring, epichlorohydrin was added to the solution from the addition funnel in an above-surface, dropwise manner. The addition rate of the epichlorohydrin was such that temperature of the flask contents rose to 68°C in 30 minutes when BCM was noticed to start refluxing. The addition of the epichlorohydrin was stopped to allow the temperature to decrease to 60⁰C, and when this temperature was reached the epichlorohydrin additions resumed in the same manner. Thus, during the addition of the epichlorohydrin, the addition rate was adjusted constantly to keep the temperature of the flask contents in the range of from 60 to 70⁰C. It should be noted that when the last portion (about 30 mL) of a total of 4.0 equivalences of epichlorohydrin was added, the temperature of the flask contents no longer "bounced" back up. After the last of the epichlorohydrin was added, an excess amount (10% of the amount outlined in Table 3) was added to ensure that the reaction was complete. H and P NMR were conducted on the contents of the flask, and the presence of excess epichlorohydrin was observed, indicating the completion of the exothermic reaction and thus the formation of the flame retardant composition, Composition C. The contents of the flask were then allowed to cool to room temperature, and it was observed that the color of the flask contents τurneα irom light yellow to yellow. The total reaction time was 4 hours.

[0031] The product mass in the flask was observed to comprise an organic layer and an aqueous layer in an emulsion, and this product mass was washed with a 15% Na₂CO₃ solution (500 mL x 2) followed by saturated NaCl (500 mL x 4) solution (30wt.% NaCl, based on the solution) until the pH of the aqueous layer reached about 8, The yellow color of the product mass immediately disappeared with the addition of the Na₂CO₃ solution It should be noted that about 100ml of BCM was added during the washing of the product mass to help phase separation between the organic and aqueous layers. The organic layer was separated from the aqueous layer by removing the aqueous layer via vacuum and filtered through a fiberglass plug. BCM was then removed from the organic phase by atmospheric and vacuum distillation, and the organic phase was further dried by heating it to 100⁰C under 17 mm Hg for 3 hours with magnetic stirring, when it was observed that there was no more BCM bubbling out. The flame retardant composition thus obtained was a near-colorless viscous material having a slight cloudiness that weighed approximately 1000.2 grams (yield greater than 95%), and was observed, by H and P NMR, to have the structure of Composition C detailed in the reaction scheme above. Composition C was also analyzed by Thermogravimetric Analysis ("TGA") for the presence of halogens (H and P NMR), for the acid number and also color and viscosity. The results of these measurements are indicated in Table 4 below.

EXAMPLE 3

[0032] In this example, using TDCP as a reference, the flammability and process ability performance of Compositions A and C were carried out using the general polyurethane formulation in Table 5. It should be noted that "Amount" as it appears in Table 5 is the amount of the specific component in parts per hundred ("pph"), based on the polyol. Also, the "Flame Retardant Composition Load" was varied based on the formulation, as indicated in Table 6.

[0033] After formulation, the formulations were analyzed via FMVSS 302 and CaI 117 flammability tests and compared to similar formulations containing TDCP. The amount of flame retardant compositions, i.e. Composition A and Composition C, and the results of these experiments are contained in Table 6, below.

[0034] As can be seen in Table 6, Composition A and Composition C, flame retardant compositions according to the present invention, have good results for the FMVSS 302 and CaI 117 flammability tests. In fact, the results indicate that these compositions are comparable as flame retardants to TDCP. EXAMPLE 4

[0035] As with all flame retardants, thermal data is extremely important because it reveals key characteristics that show how a certain compound will behave at a given temperature. Thus, Composition A and Composition C were analyzed by Differential Scanning Calorimetry ("DSC") to determine their thermal transitions. The results of these measurements as well as the TGA analysis of Composition A and Composition C along with the TGA and DSC for TDCP are summarized in Table 7, below.

[0036] As illustrated in Table 7, Composition A and Composition C have thermal properties equal to or better TDCP.

Claims

WHAT IS CLAIMED

1) A flame retardant composition comprising:

wherein Z is selected from:

, or

wherein if Z is A), Xi, X₂, X₄, and X₅ are each independently selected from:

Y is selected from:

;v:

and wherein if Z is B), X₁, X₂, and X₃, are selected from: I, II, III, IV₅ V, VI, VII,

2) The flame retardant composition according to claim 1 wherein Z is A).

3) The flame retardant composition according to claim 2 wherein Y is selected from i or //, and each X is selected from I or II.

4) The flame retardant composition according to claim 2 wherein Y is selected from Ui or iv and X₁, X₂, X₄, and X₅ is independently selected from I, II, III, IV, V, VI, and VII. 5) The flame retardant composition according to claim 2 wherein said flame retardant composition has the formula:

6) The flame retardant composition according to claim 2 wherein said flame retardant composition has the formula:

7) The flame retardant composition according to claim 2 wherein said flame retardant composition has the formula:

8) The flame retardant composition according to claim 2 wherein said flame retardant composition has the formula:

9) The flame retardant composition according to claim 2 wherein said flame retardant composition possess at least one of: a) an acid number of less than 0.3, as determined by titration with KOH; b) a hydrolytic stability consistent with the hydrolytic stability of TDCP; c) a 10% weight loss at about 250 to about 300⁰C as determined by thermogravimetric analysis conducted under conditions including a temperature ramp of 10°C/minute up to 500⁰C in air; d) an APHA color index of less than 100, e) do not discolor polyurethane foams.

10) The flame retardant composition according to claim 9 wherein said flame retardant composition possesses at least two of the characteristics i) through ix).

11) The flame retardant composition according to any of claims 5-9 wherein said flame retardant composition possesses all of the characteristics i) through ix).

12) The flame retardant composition according to claim 1 wherein Z is B).

13) The flame retardant composition according to claim 12 wherein X₁, X₂, and X₃ are each independently selected from IX or X.

14) The flame retardant composition according to claim 12 wherein Xi, X₂, and X₃ are the same and are all selected from either IX or X.

15) The flame retardant composition according to claim 12 wherein two OfX₁, X₂, and X₃ are each independently selected from IX or X, and one of Xi, X₂, and X₃ is selected from I₅ II, III, IV, V, VI, VII, and VIIL

16) The flame retardant composition according to claim 12 wherein two OfX₁, X₂, and X₃ are each independently selected from IX or X, and one of X₁, X₂, and X₃ is selected from I, II, III, IV, V, VI, and VII.

17) The flame retardant composition according to claim 12 wherein two Of X₁, X₂, and X₃ are IX or X, and one of X₁, X₂, and X₃ is II or VIII. 18) The flame retardant composition according to claim 12 wherein two of Xi, X₂, and X₃ are IX or X, and one of Xi, X₂, and X₃ is II.

19) The flame retardant composition according to claim 12 wherein said flame retardant composition possess at least one of: a) an acid number of less than 0.3, as determined by titration with KOH; b) a hydrolytic stability consistent with the hydrolytic stability of TDCP; c) a 10% weight loss at about 250 to about 300⁰C as determined by thermogravimetric analysis conducted under conditions including a temperature ramp of 10°C/minute up to 500⁰C in air; d) an APHA color index of less than 100, e) do not discolor polyurethane foams.

20) The flame retardant composition according to claim 12 wherein said flame retardant composition possesses at least two of the characteristics i) through ix).

21) The flame retardant composition according to any of claims 12-18 wherein said flame retardant composition possesses all of the characteristics i) through ix).

22) A polyurethane foam formulation comprising: a) a polyurethane foam; and, b) a flame retarding amount of a flame retardant composition selected from those having the general formula:

wherein Z is selected from:

or

B)

wherein if Z is A), Xi, X₂, X₄, and X5 are each independently selected from:

Y is selected from:

III

and wherein if Z is B)₅ X₁, X₂, and X₃, are selected from: I, II, III, IV, V₅ VI₅ VII₃

;orX)

23) The polyurethane foam formulation according claim 22 wherein said flame retarding amount of said flame retardant composition is in the range of from about 1 to about 25wt.%, based on the flame retardant formulation.

24) The polyurethane foam formulation according to claim 22 wherein said flame retarding amount of said flame retardant composition is in the range of from about 5 to about lθwt.%, based on the flame retardant formulation.

25) The polyurethane foam formulation according to claim 23 wherein Z is A).

26) The polyurethane foam formulation according to claim 25 wherein Y is selected from i or H, and each X is selected from I or II.

27) The polyurethane foam formulation according to claim 25 wherein Y is selected from in or /v and Xj, X₂, X₄, and X₅ is independently selected from I₅ II, III, IV, V, VI, and VII.

28) The polyurethane foam formulation according to claim 25 wherein said flame retardant composition has the formula:

29) The polyurethane foam formulation according to claim 25 wherein said flame retardant composition has the formula:

30) The polyurethane foam formulation according to claim 25 wherein said flame retardant composition has the formula:

31) The polyurethane foam formulation according to claim 25 wherein said flame retardant composition has the formula:

32) The polyurethane foam formulation according to claim 25 wherein said flame retardant composition possess at least one of: a) an acid number of less than 0.3, as determined by titration with KOH; b) a hydrolytic stability consistent with the hydrolytic stability of TDCP; c) a 10% weight loss at about 250 to about 300⁰C as determined by thermogravimetric analysis conducted under conditions including a temperature ramp of 10°C/minute up to 500⁰C in air; d) an APHA color index of less than 100, e) do not discolor polyurethane foams.

33) The polyurethane foam formulation according claim 25 wherein said flame retardant composition possesses all of the characteristics i) through ix).

34) The polyurethane foam formulation according to claim 23 wherein Z is B).

35) The polyurethane foam formulation according to claim 34 wherein X₁, X₂, and X₃ are each independently selected from IX or X. 36) The polyurethane foam formulation according to claim 34 wherein X₁, X₂, and X₃ are the same and are all selected from either IX or X.

37) The polyurethane foam formulation according to claim 34 wherein two Of X₁, X₂, and X₃ are each independently selected from IX or X, and one Of X₁, X₂, and X₃ is selected from I, II, III, IV, V₃ VI, VII, and VIII.

38) The polyurethane foam formulation according to claim 34 wherein two of Xj, X₂, and X₃ are each independently selected from IX or X, and one Of X₁, X₂, and X₃ is selected from I, II, III, IV, V, VI, and VII.

39) The polyurethane foam formulation according to claim 34 wherein two of X₁, X₂, and X₃ are IX or X, and one of X₁, X₂, and X₃ is II or VIII.

40) The polyurethane foam formulation according to claim 34 wherein said flame retardant composition possess at least one of: a) an acid number of less than 0.3, as determined by titration with KOH; b) a hydrolytic stability consistent with the hydrolytic stability of TDCP; c) a 10% weight loss at about 250 to about 300⁰C as determined by thermogravimetric analysis conducted under conditions including a temperature ramp of 10°C/minute up to 500⁰C in air; d) an APHA color index of less than 100, e) do not discolor polyurethane foams.

41) The polyurethane foam formulation according to claim 34 wherein said flame retardant composition possesses all of the characteristics i) through ix).