REACTIVE, LOW VISCOSITY AND BIOBASED PHOSPHORUS CONTAINING POLYOL WITH FIRE RETARDANT PROPERTIES

Inventors: Jonathan CURTIS; Xiaohua KONG; Yuan Yuan Zhao; Siew Meng LIEW Assignee: The Governors of the University of Alberta

File No. 55326.257 PCT

Field of the Invention

[0001] The invention relates to phosphorus containing polyols with fire retardant properties, and methods of producing and using them.

Background

[0002] Polymeric materials, such as polyurethanes (PUs) are traditionally derived from petrochemical polyols. However, with the realization of the limited availability of fossil fuel resources, different technologies to viably produce polyols from renewable resources are desirable. Unsaturated plant or animal oils/fats are abundant and cheap renewable resources which may represent a major potential alternative source of chemicals suitable for developing environmentally friendly products. In order to produce reactive materials which can be either utilized as additives or used to produce valuable polymeric materials, functional groups such as hydroxy., epoxy, or carboxyl groups have to be introduced into the unsaturated triacylglycerol molecules. With vegetable oil based polyols, the most widely studied reaction routes include hydroformylation followed by hydrogenation, ozonolysis followed hydrogenation, and epoxidation followed by hydroxylation/transesterification. [0003] However, PU materials have inherently high flammability, and particularly PU foams used as insulation. Flame retardants must therefore be added to these organic materials to attenuate their flammability and to comply with the required fire standards. This adds extra cost and generates more technical issues for foam production, such as component miscibility. One solution is to incorporate heteroatoms such as halogens, Si or P into the polyol molecules so to produce a functional ized polyol. These molecules can both undergo the reactions necessary to make PU in the usual way, and can function within that PU polymer as a flame retardant, avoiding or limiting the need for additional fire retardant additives. This may result in both a cost reduction and a process simplification.

[0004] Recently, soy-phosphate ester polyols have been produced from epoxidized soybean oil or its fatty acid esters in the presence of phosphoric acid (H3PO4), with or without solvent However, all of the soy-phosphate polyols reported have low hydroxyl functionality (hydroxyl number less than 250 mg KOH/g), high acidity (acidity number as high as 1 10 mg KOH/g), only secondary hydroxyl groups and high viscosity, which severely limit their reactivity and usefulness in practical applications. For example, curing of the PU produced from polyols with only secondary hydroxyl groups will be too unreactive to use to any large extent in an application such as PU spray foam. In addition, it would also be much more favorable to use low viscosity polyols in a spray process, a reaction injection molding process or a high pressure molded foam process.

[0005] Therefore, there remains a need in the art for modified polyols which mitigate some or all of the prior art. In particular, it would be desirable to produce polyols which display fire retardant properties, combined with high reactivity and low viscosity. Summary Of The Invention

[0006] In one aspect, the invention may comprise a novel compound comprising a dioxaphospholane ring linked to at least two fatty acid moieties, each comprising a terminal hydroxyaikyl or hydroxyheteroalkyl ester. In some embodiments, the compound has the structure of Formula I:

wherein:

• nl, n2, n3 and n4 may be the same or different, and nl+n2 is an integer greater than or equal to 4 and less than or equal to 26, and n3+n4 is an integer greater than or equal to 4 and less than or equal to 26; and

• Rl and R2 may be the same or different, and is a branched or unbranched, substituted or unsubstituted alkyl group or heteroalkyl group. [0007] The fatty acid moieties may be derived from any unsaturated fatty acid, such as oleic, linoleic, linolenic, myristoleic, palmitoleic , elaidic, vaccenic, linoelaidic acid, linolenic, arachidonic, cicosapentaenoic, erucic and docosahexaenoic acids. The fatty acid may have a chain length from C4 to C30, with 1-6 double bonds. Preferably, the fatty acid has a chain length of C12-C22 and most preferably C16-C20.

[0008] The position of the dioxaphospholane ring(s) can vary, depending on the location of unsaturation on the starting ester(s). In some embodiments, each hydroxyalky] ester may bear multiple dioxaphospholane rings if the starting cstcr(s) has multiple double bonds, such as for linoleic and linolenic acid. Isomeric forms of the fatty acid diol ester are included in the scope of the present invention, particularly those in which the positions of the secondary hydroxyl group and the P-O-C connection to the dioxaphospholane ring on the lower fatty acyl chain in the above structure are reversed.

[0009] In another aspect, the invention may comprise a method of producing a phosphorus containing polyol composition, comprising the steps of producing an cpoxidized fatty acid having a hydroxyalkyl ester, and phosphorylating the cpoxidized fatty acid with phosphoric acid. The diol used in making the hydroxyalkyl ester can vary, for example, ethylene glycol, propane diol, butane diol, pentane diol, hexane diol and so on. Isomers (for example 1,2 propane diol) or polyhydroxy alcohols are also possible, which allows for the introduction of secondary alcohols. The ester groups can also contain amine functionality as is known with other polyols. These can increase the heteroatom percentage and may provide extra reactivity.

The epoxidized fatty acid may be derived from any unsaturated triglyceride oil, such as canola, soy, palm, camel ina, sunflower, hemp, flax, or tallow oil. Epoxidation can be complete (all -HC=CH- double bonds converted to epoxide form) or partial (some fraction of -HC=CH- double bonds converted to epoxide form).

[0010] In some embodiments, the epoxidized fatty acid comprises 3-hydroxypropyl-9,10- epoxystearate (HPES). In some embodiments, the phosphorylation reaction occurs in a suitable solvent such as acetone or tert-butanol, or is solvent-free. In some embodiments, the phosphoric acid is at least 85% phosphoric acid, and preferably greater than 99% phosphoric acid.

[001 II In another aspect, the invention may comprise a polyol composition comprising a dioxaphospholanc fatty acid diol ester, which has a phosphorus content of greater than about 0.4%, a bydroxyl number of greater than about 240 mgKOH/g, an acidity number no greater than about S.O mgKOH/g, and a viscosity no greater than about 13 Pa s at 25 °C.

Brief Description of the Drawings

[0012] The drawings which accompany and form part of the specification and arc included to further demonstrate certain embodiments or various aspects of the invention. In some instances, embodiments of the invention can be best understood by referring to the accompanying drawings in combination with the detailed description presented herein. The description and accompanying drawings may highlight a certain specific example, or a certain aspect of the invention. However, one skilled in the art will understand that portions of the example or aspect may be used in combination with other examples or aspects of the invention.

[0013] Figure 1 shows a flow injection ESI mass spectra. [0014] Figure 2 shows ESI spectra at (a) m/z 811 and (b) 793. [0015] Figure 3 shows extracted ion chromatograms.

[0016] Figure 4 shows GPC chromatograms of FR-PCP and starting HPES. CPEP refers to FR-PCP-1 and FR-PCP-2.

[0017] Figure 5 shows H-NMR spectrum of FR-PCP-2 polyol. [0018] Figure 6 shows 31P-NMR spectrum of FR-PCP-2 polyol. [0019] Figure 7a shows FTIR of FR-PCP-2 polyol.

[0020] Figure 7b shows FTIR differential spectrum of FR-PCP-2 polyol, after subtraction from the initial mixture in the 1400-700 cm' ¹ .

[0021] Figure 8a shows a TGA thermograph of polyurethane foams with different concentrations of FR-PCP-2 polyol (denoted as CPEP-2).

[0022] Figure 8b shows a DTGA thermograph of polyurethane foams with different concentrations of FR-PCP-2 polyol (denoted as CPEP-2).

[0023] Figure 9 shows a photograph of PU foams comprising 0%, 50% and 100% FR-PCP-2. Detailed Description of Embodiments of the Invention

[0024] This invention comprises a biobased phosphorus-containing polyol that includes primary hydroxyl groups, high functionality, and at the same time relatively low viscosity. In this specification, one example of this novel polyol is referred to as "FR-PCP" (fire-retardant phosphorus-containing polyol). FR-PCP has suitable polyol properties to successfully produce polyurethane (PU) foams using polyol compositions of up to and including 100% FR- PCP. Foams made using 100% FR-PCP are shown to have the ability to self-extinguish. Exemplary methods used to synthesize FR-PCP from vegetable oil derivatives are described below.

[0025] As used herein, "aUcyl" refers to a straight or branched aliphatic hydrocarbon group, preferably a CI-CM alkyl, more preferably Ci-Cioalkyl, most preferably Ci-Ce. "Hctcroalkyl" refers to a straight- or branched-chain alkyl group preferably having from 2 to 14 carbons, more preferably 2 to 10 carbons in the chain, one or more of which has been replaced by a heteroatom selected from S, O, P and N.

[0026] In one aspect, the invention comprises a method to produce FR-PCPs using low-cost, simple and industrially feasible chemistry from unsaturated plant or animal oils, which are biobascd and thus arc a renewable feedstock. The invention overcomes a significant hurdle to include primary hydroxyl groups into plant oil-based phosphate ester polyols, to increase the hydroxyl functionality, to decrease the acidity and to decrease the viscosity of the product. These polyols could be used in diverse applications including polyurethanes, flame relardants, surfactants, pressure sensitive adhesives, coatings and lubricants.

[0027] The FR-PCPs act as effective fire retardants. Conventionally, these polyols may be added to a polyoi blend used to make PU products, for example, at levels of <20%. However, because the FR-PCPs are reactive polyols with a high content of primary hydroxyl groups they can also be used to replace >50%, most or all of the polyol content in PU products.

Furthermore, the FR-PCP described may contain a biocontent of greater than about 90% with the remaining 10% or less originating from phosphoric acid. As used herein, "biocontcnt" refers to the proportion of mass which originates or is derived from a biological product. Thus, FR-PCPs may be used to create PU products having a high biocontent, greater than about 90%.

[0028] Generally, the synthetic routes for producing FR-PCPs from an unsaturated triacylglycerol (TAG) comprise the steps of: (a) epoxidizing the unsaturated TAG to obtain an epoxidized unsaturated TAG; and (b) transesterifying the cpoxidized unsaturated TAG using a diol in the presence of a catalyst and/or a solvent, to produce a hydroxylated fatty acid alkyl ester epoxide. In one example, the hydroxylated fatty acid alkyl ester epoxide comprises 3- hydroxypropyl-9,10-epoxystearate (HPES), which is alternately named 3-hydroxypropyl 8-(3- octyloxiran-2-yl) octonaoate. Suitable methods and compounds for epoxidation and transesterifi cation are described in co-pending PCT Application WO 2016/205958 "Method for polyol synthesis from triacylglyceride oils", the entire contents of which are incorporated herein by reference, where permitted.

[0029] Any TAG oil containing unsaturated fatty acid chains can be used as starting material.

In some embodiments, the unsaturated TAG oil comprises canola oil, high oleic canola oil, sunflower oil, juvenile canola oil, flax oil, camelina oil, solin oil, yellow mustard oil, brown mustard oil, oriental mustard oil, palm oil olein, palm oil, palm kernel oil, soy oil, high erucic acid rapeseed oil, hemp oil, corn oil, olive oil, peanut oil, safflower oil, cottonseed oil or mixtures thereof. Edible oils which are fully refined, (for example, degummed, bleached, deodorised) can be used as can non-refined oils that may not be food grade, such as juvenile or "green" canola, camelina oil, high erucic acid rapeseed oil. Use of different oils with different triglyceride compositions, when fully or partially epoxidized, will result in different polyols, molecular weights, hydroxyl numbers, and viscosities giving access to a wide variety of polyols for various purposes.

[0030] In some embodiments, biobascd epoxidized canola oil (ECO) is used to form the hydroxylated epoxidized fatty acid, as shown in exemplary Scheme 1 below.

[0031] In some embodiments, in step (a), the unsaturated TAG oil or HCO is epoxidized by any suitable method, such as with formic acid and an oxidizing agent or with a chemo- enzymatic method. In some embodiments, the oxidizing agent comprises hydrogen peroxide. In some embodiments, the unsaturated TAG oil is mixed with the oxidizing agent at a temperature from about 20° to about 40° C, more preferably from about 20° to about 30° C. In some embodiments, after the oxidizing agent is added, the temperature is then gradually increased to about 40° to about 60 ⁰ C, as the acid is added slowly. In some embodiments, the epoxidation of the unsaturated TAG oil is catalyzed by an enzyme, such as lipase. In some embodiments, the resulting epoxidized TAG oil is extracted using an organic solvent and dried. [0032] In some embodiments, in step (b), the diol may comprise 1,2-propane diol, 1,3- propane diol, 1,4-butane diol, ethylene glycol, glycerol, glycerol acetates, or mixtures thereof. In some embodiments, the diol comprises 1 ,3 -propane diol. In some embodiments, the catalyst comprises an alkoxide, such as sodium methoxide, dissolved in a suitable solvent. To help avoid premature ring opening during transesterification, freshly prepared anhydrous alkoxide may be used.

[0033] In some embodiments, the epoxidized TAG oil is mixed with sodium methoxide solution and the diol at a temperature of about 40° to about 70° C, and more preferably about 50° to about 60 ° C. In some embodiments, anhydrous sodium methoxide is dissolved in acetone. In some embodiments, the epoxidized TAG is mixed with sodium methoxide solution and the diol for between about two to about six hours, preferably about four hours. The reaction may be stopped by addition of an acid to neutralize the catalyst. In some embodiments, the acid may comprise a mineral acid such as sulfuric acid, or an acid immobilized on a solid support, such as solid beads. Preferably, the solid beads comprise a heterogeneous macroreticular ion exchange resin operating in strong anion exchange mode. Following the reaction, the solvent may be removed by evaporation.

[0034] Transesterification of the epoxidized fatty acid with a diol introduces primary hydroxyl groups into the epoxidized fatty acid structure. In addition, in some embodiments, because the molecular weight of HPES is about 3 times lower than epoxidized soybean oil, the molecular weight of the resulting P-containing polyol is also lower than soy-phosphate ester polyols. This contributes towards the reduced viscosity of the product. [0035] The phosphorylation reaction may take place in any suitable solvent, such as acetone or lert-butanol (Guo, Y. et al, Journal of the American Oil Chemists Society 2007, 84, (10), 929-935), or under solvent-free conditions. The choice of solvent or absence of solvent may be optimized by one skilled in the art (along with reaction time and others) to tailor the final result desired, including properties such as acid value, residual oxirane content, and hydroxyl value. The solvent used can be distilled out and reused within the process.

[0036] In summary, one aspect of the present invention comprises a method comprising the formation of a mixture of phosphorus-containing polyol structures from an epoxidized fatty acid esterified to a diol such as 1 ^-propanediol or 1 ,4 butanediol. The major final products of these reactions contain two such fatty acid diol esters connected via a dioxaphospholane ring (Scheme 2, compound 4). along with varying amounts of an ether linked dimer (compound 6).

Scheme 2 chemistry of the reaction of HPES and phosphoric acid in tert-butanol

[0037] The resulting polyols incorporate phosphorous and primary hydroxyl groups on the hydroxypropyl ester groups, resulting in high reactivity and flame resistance properties along with low viscosity. The final product (compound 4 and similar), is formed via dehydration of the phosphate triester/diester intermediate, and contains the cyclic dioxaphospholane group. Therefore, in this invention formation of a high percentage of compound 4 and its analogues during polyol synthesis is desirable and results in a more stable polyol product.

[0038] The novel phosphorus containing polyols can be used as both building materials and flame retardant simultaneously for polymer production (particularly in polyurethanes) due to their high phosphorus content. The described methods herein successfully use a canola oil feedstock, however, the same synthetic technique can be applied to any unsaturated oil, resulting in possible products with a range of phosphorus contents, viscosities, hydroxyl values etc.

Examples - The following examples are intended to illustrate embodiments of the present invention, and not be limiting of the claimed invention.

Example 1

[0039] I . Synthesis of fire-retardant phosphorus-containing poly ol- 1 (FR-PCP- 1 )

[0040] 1.5 gram of 85% phosphoric acid (0.013moI) was dissolved in 20ml of tert-butanol in a 250ml 3 -neck round bottom flask under slow rate mechanical stirring. To this was added dropwise 30gram of HPES (0.084mol) in 45mins. The temperature of the reaction was at 40 °C and increased to 70°C after completion of the addition of HPES. The resulting mixture was stirred for 3 hrs under reflux condition. The solvent and water was removed with a rotary vacuum evaporator and the products were collected.

[0041] 2. Identification of the products by HPLC-MS/MS [0042] lmg/ml of products was prepared in dichloromethane (DCM) and then diluted to 0.1 mg/ml in isopropanol. 2μ1 of this solution was introduced to high resolution Q-TOF mass spectrometer in positive or negative ESI mode by flow injection at 0.2ml/min flow rate using isopropanol as a mobile phase and with a post-column addition of 40mM ammonium acetate in mcthanol/isopropanol (3/1) at 20uJ/min flow rate. The resulting mass spectrum was shown in Fig. 1. The ions observed at m/z 811 and 793 are prolonaled ions of compounds 3 and 4, respectively (Scheme 2), while the ions at m/z 810 and 815 correspond to ammonium and sodium adducts of compound 4. The elemental composition of the ion at m/z 811.5712 was determined to be ³¹¹⁽¹ ^ ^{of ion at} 793.5562 to be consistent with the elemental composition of compounds 3

and 4 (Scheme 2). The elemental composition of ions at 810.5819 and 815.5387 are determined to be

which confirmed that ion seen at m/z 793 is the protonated adduct of compound 4 not the fragment ion from compound 3 with the neutral loss of water.

[0043] In order to further confirm the structure of compound 3 and 4, MS/MS of ions at m/z were conducted. The MS/MS spectra of the ion m/z 811 shows

the product ions at m/z 793, 775, 455, 437, 419, 357 and 339.The ions at m/z 793 and 775 are due to neutral loss of water from compound 3 which contains 5 hydroxyl groups. The C-0 linked phosphate cleavage gives rise to fragment ions at m/z 455 and 357, where the ion at m/z

455 contains the phosphate group while ion at m/z 357 does not. The neutral loss of water from the fragment ion at m/z 455 gives rise to further fragment ions at m/z 437 and 419. The fragment ion at m/z 339 was formed from the neutral loss of water from the fragment ion at m/z 357. Similarly, the MS/MS spectra of ion at m/z 793 showed the fragment ions at m/z 775, 437, 419, 361 and 339. Cleavage of C-O linkage of the phosphate group in compound 4 was observed to give rise to the ions at m/z 437 containing a phosphate group. Unlike what was observed for compound 3, an ion at m/z 3S7 was not observed in the MS/MS spectrum of compound 4, possibly due stabilization of the charge on the ion at m/z 437 which retains the stable 5-membered dioxaphospholane ring structure. The ion at m/z 361 was from the loss of 1 ,3-propanediol from ion at m/z 437. The much smaller intensity of ion at m/z 339 compared with compound 3 is also probably due to the stability of ion at m/z 437. Furthermore, negative ESI MS/MS of ion at m/z 791 (deprotonated compound 4) was carried out (data not shown). A pair of ions at m/z 97 and 79 was observed, indicating the existence of phosphate in this molecule.

{0044] The accurate mass measurement and tandem mass spectra of ion at m/z 811 and 793 supported the conclusion that they are protonated ions of compounds 4 and 3 in scheme 2.

[0045] In addition to the two products, the ions at m/z 37S, 731 and 730 were observed as well. They are pronated ions of compound 5, 6 and ammonium adducts of compound 7.

Through the accurate mass measurement and MS/MS tandem mass spectra, the structure of these three ions were proposed to be compound 5, 6 and 7 in Scheme 2. An ion at m/z 357 was seen in the spectra, indicating the existence of unreacted HPES (compound 2 in scheme 2).

[0046] A silica HPLC column separation using hexanes and isopropanol as mobile phase coupled with mass spectrometer was also employed to analyze the products. Compound S, 6, 7 and unreacted HPES are well separated from compound 3 and 4. Compounds 3 and 4 were eluted at the same retention time. The elution order of these compounds arc unrcacted HPES (compound 2 in scheme 2), compound 7, compound 6, compound S, compound 3 and 4, with the increase of the polarity and existence of more hydroxyl group on the molecules. This result supports the proposed structures in Scheme 2. Fig. 3 showed the extracted ion chromatogram (XIC) of compounds 2-7. The intensity of compound 7 is too low to show in the

chromatogram.

[0047] With the experimental condition described above, the hydroxyl number of FR-PCP-1 is 240 mg KOH/g, its acid value is 2.7 mg KOH/g. its viscosity at 25°C is 1.56 Pa s. This viscosity is 3 times less than reported for soy-phosphate ester polyols with the same hydroxyl number. The P content is about 0.4%.

[0048] Gel permeation chromatography (OPC, Figure 4) shows that there are three well identified peaks corresponding to the mixture of oligomer with highest average molecular weight around 1200, the main products with average molecular weight around 700 and unreacted HPES. The highest average molecular weight of 1200 is similar to the soy- phosphate ester polyols monomer, but about three times less than soy-phosphate triester. There is still about 40% oxirane ring unreacted under this condition, therefore some steps of the reaction were optimized, see Example 2.

Example 2

[0049] 1. Synthesis of flame-retardant phosphorus-containing polyol-2 (FR-PCP-2)

[0050] Considering that the major by-product (compound 5 from Fig. 3) was produced by the opening of the HPES epoxy ring by water, crystalline high purity phosphoric acid (>99%) was used in this example to reduce by-products and increase P content 30 g of premelted HPES (0.084mol) was dissolved in 30 ml of tert-butanoL 2.4 g of crystalline phosphoric acid (0.024mol) was charged into a 250ml 3 -neck round bottom flask and preheated to 40° C. To this was added the HPES/t-butanol solution slowly under mechanical stirring. The temperature of the reaction was increased to 70°C after completion of the addition of phosphoric acid. The reaction was monitored by FTIR until the intensity of hydroxyl and oxirane bands reached equilibrium. The solvent was removed with a rotary vacuum evaporator and FR-PCP-2 was collected.

[0051] In another example, the phosphorylation step was performed without solvent at temperature of 120°C under vacuum to remove water which may form.

[0052] 2. Identification of the products by HPLC-MS/MS

[0053] The same LC-MS experiments described above for FR-PCP-1 were also carried out for FR-PCP-2. This showed that the compounds in FR-PCP-2 were found to be the same as in FR-PCP-1. From the extracted ion chromatograms (Fig 3), it can be seen that the amount of unre acted HPES (compound 2) decreased relative to other compounds which indicates that a higher proportion of oxirane rings were opened (Fig. 3).

[0054] 3. Identification of the products by 'H-NMR, ³¹ P-NMR and FTIR

[0055] The Ή-NMR analysis of the FR-PCP-2 mixture (Figure 5) indicates a transformation of HPES to polyol. The signals characteristic of the phosphate groups are localized between

4.00 to 4.40 ppm. Compound 4 is characterized in the Ή-NMR by signal at δ 4.22 ppm corresponding to the hydrogen -CH-O-P of the dioxaphospholane cycle. Compound 3 is characterized by the signals of -CH- hydrogen groups at δ 3.70 and 4.13 ppm corresponding respectively to the hydrogen of the hydroxyl group and that of phosphate diester group. In addition, compounds 5 and 6 are characterized by the signals of at -CH- hydrogen groups at δ 3.39 ppm and 3.45 ppm corresponding to the hydrogen of the hydroxyl group and that of the ether group, respectively. The appearance of diol compound 5 from apparent epoxide hydrolysis, even in the absence of water, is most likely a further demonstration of the formation of dioxaphospholane, with water as the expected byproduct.

[0056] The incorporation of phosphorous into the polyol structure was further confirmed by ^3I P-NMR. In the ^3, P-NMR spectrum (Figure 6) of FR-PCP-2 was observed a signal between 0 and O.S ppm characteristics of phosphate diesters [ROP(0)(OH)OR] (compound 3) and a signal between 14.0 and 1S.6 ppm characteristic of the cyclic dioxaphospholane group

[ROP(0)(OR)2] (compound 4).

[0057] In the FTIR spectrum of the FR-PCP-2 polyol (Fig. 7a), a new band at around 1000 cm-' (P-O-C) was detected not seen in in the FTIR spectrum of HPES, as well as at 1053 cm" ¹

( -C-O). At the same time the weak band at 824 cm" ¹ due to the epoxide group disappeared, due the incorporation of P with the opening of oxirane ring. As the reaction proceeds, the intensity of P-O-C ester bond decrease, meanwhile the intensity of those bands corresponding to [ROP(0)(OR)2] (1275cm ^"1 ) and P-OH (920cm ^'1 ) groups increase, as shown in Fig. 7b. This suggests that compound 4 and its analogues are formed via dehydration from an acyclic phosphate triester/di ester intermediate, resulting in a more stable polyol product. The broad band at 3401 cm ^"1 in Fig. 7a is due to -OH absorption, which demonstrates that the reaction with pure phosphoric acid did not eliminate hydroxyl groups in the FR-PCP molecules. [0058] The hydroxyl vahie of FR-PCP-2 is 310 mgKOH/g, its acid value is 4.0 mgKOH/g, its viscosity at 2S°C is 8.56 Pa-s and its P content is about 2%. GPC (Figure 4) shows that the oligomer content of FR-PCP-2 is much higher than that of FR-PCP-1. Both of the high hydroxyl value and high oligomer content result in the observed higher viscosity for FR-PCP- 2 than FR-PCP-I . However, compared to the reported soy-phosphate ester polyols with similar P content, the product prepared in this work has primary hydroxyl groups (vs all secondary), much higher hydroxyl value, lower molecular weight, lower acid value as well as lower viscosity. Therefore, it has the potential being used in polyurethane rigid foam both as the reactive polyol and as the flame retardant

[0059] 4. Characterization of polyurethane foams

[0060] Three polyurethane foams were prepared using a typical foam formula but with 0, 50 and 100% of the polyol content replaced by FR-PCP-2 polyol. These were coded as FR-PCP- and The thermal stability and thermal degradation of

the above samples were investigated by thermal gravimetric analysis (TGA). The TGA and derivative thermogravimctric curves are shown in Figure 8(a) and (b) respectively, and some decomposition data is summarized in Table 1.

[0061] The degradation process of all the three samples can be divided into two stages. In the first stage of decomposition, the foam without FR-PCP-2-0% lost 5 wt% before reaching 278°C and the maximum weight loss was at 336°C, with about 62% of its weight was lost by the end of this stage. The 5 wt% weight loss temperatures for FR-PCP-2-50% and FR-PCP-2- 100% were shifted to the lower temperatures of 267°C and 253°C, with the maximum weight loss at 315°C and 306°C, respectively. In the first stage, only 45% and 40% of weight was lost for FR-PCP-2-50% and FR-PCP-2-100%, respectively. The second stage of decomposition is found in the range of 330 to 500 °C which is attributed to the degradation of hydrocarbon chains.

[0062] As shown in Figure 8a and Table 1, the Tswot of both samples containing FR-PCP-2 is lower than that of foam without FR-PCP-2. This can be attributed to the lower stability of P- O-C bonds compared with other bonds. In the second decomposition stage, the maximum weight loss temperatures (Tdnwa) arc shifted to higher temperature. Increased stability of FR- PCP-2 containing foams at this stage could result from the formation of more thermal stable intermediates induced by phosphorus acid derivatives and promoted the formation of char at low temperature. Moreover, the char residues of FR-PCP-2-50% and FR-PCP-2-100% are higher than that of FR-PCP-2-0%, as listed in Table 1. This can be explained by the feet that samples have P-O-C bonds decomposed at lower temperature and formed a phosphorus-rich layer which protected underlying PU matrix. This stable physical protective barrier on the surface of PU may insulate the underlying PU matrix from the heat and thus provides barrier properties which enhances the thermal stability of the PUs. [0063] PU flammability was evaluated by means of limiting oxygen index (LOI). It is found that PU foam without FR-PCP-2 polyol has an LOI of 19.1 %, addition of 100% FR-PCP-2 increase LOI about 10.5%. Furthermore, the use of increasing levels of phosphrous (%P) in PU foam added in form of FR-PCP-2 polyols, results in a corresponding increase in LOI from 20.1% at 0.56% P to an LOI of 21.1% at 0.98% P.

[0064] Qualitative evidence may be seen in Figure 9, showing the results of combustion of PU foam made using FR-PCP-2 polyol.

• PU1 - 0% FR-PCP-2 (0% P)

• PU2 = 50% FR-PCP-2 (0.52% P)

• PU3 = 100% FR-PCP-2 (1.09%P; self-extinguished after 20s) Definitions and Interpretation

[0065] The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. [0066] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

[0067] References in the specification to "some embodiments", "an embodiment", etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any element or feature may be combined with aoy other element or feature in different embodiments, unless there is an obvious or inherent incompatibility between the two, or it is specifically excluded.

[0068] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely," "only," and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms "preferably," "preferred, " "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention. [0069] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and/or" means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase "one or more" is readily understood by one of skill in the art, particularly when read in context of its usage.

[0070] As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0071] The term "about" can refer to a variation of ± 5%, ± 10%, ± 20%, or ± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and/or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.