METHOD FOR PREPARING FLAME RETARDANTS CONTAINING PHOSPHORUS AND THEIR USE IN POLYMERIC COMPOSITIONS.

Abstract

A phosphorus-containing flame retardant is produced by reacting, at a specific reaction temperature, a mixture comprising a suitable metal or metal compound and a stoichiometric excess of unsubstituted or alkyl- or aryl-substituted phosphonic or pyrophosphonic acid relative to the metal or metal compound, wherein the phosphonic or pyrophosphonic acid is in a molten state at the reaction temperature. The chemical composition of the resulting flame retardant product provides excellent flame retardancy and exhibits high thermal stability. The flame retardants disclosed herein are useful, for example, in polymer compositions, particularly thermoplastics processed at high temperatures, in a wide range of applications.

Description

METHOD FOR PREPARING PHOSPHORUS-CONTAINING FLAME RETARDANTS AND THEIR USE IN POLYMERIC COMPOSITIONS QpL / nn / Lznz / e / YiAi This application claims the benefit of priority of U.S. Provisional Application No. e62 / 782.948, filed on December 20, 2018, and U.S. Provisional Application No. s62 / 923.446, filed on October 18, 2019, both of which are incorporated herein by reference in their entirety. A thermally stable and highly effective phosphorus-containing flame retardant is produced by a process involving the reaction of a suitable metal or metal compound with a stoichiometric excess of phosphonic or pyrophosphonic acid. The chemical composition of the resulting flame retardant, in many embodiments produced as a compound or predominantly as a compound, leads to excellent flame retardancy and exhibits high thermal stability. The flame retardants disclosed herein are useful, for example, in polymer compositions, particularly thermoplastics processed at high temperatures, in a wide range of applications. BACKGROUND Phosphonic acid salts, i.e., compounds with the formula directly below, are known flame retardants in many polymer compositions: either II R----M(+)y OH LJ p where R is an optionally substituted alkyl, aryl, alkylaryl or arylalkyl group, p is normally a number from 1 to 4, M is a metal, and ey is normally a number from 1 to 4, such that M<+>y is a metallic cation where (+)y represents the charge formally assigned to the cation. As revealed in document US 2007 / 0029532, the decomposition of phosphonic acid salts is known to occur at temperatures encountered during the processing of polyesters and polyamides, damaging the polymers in the process, for example, temperatures above 260 or 270 °C. U.S. Patent 5,053,148 reveals that heat-resistant and brittle foams can be obtained by heating phosphonic acid salts to high temperatures. In Comparative Examples 1 and 2 of U.S. Patent 9,745,449, glass-filled polyamide compositions comprising 10 to 25 wt% of the aluminum salt of methylphosphonic acid were processed at elevated temperatures. A decrease in torque was observed during compounding, consistent with polymer degradation, resulting in a final product material that was friable upon cooling, powdery after grinding, and unmoldable. Analysis of the composite material by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) provided further evidence of degradation. The observed loss of desired polymer properties is consistent with the polymer degradation described in U.S. Patent 2007 / 0029532 and with the brittle foam formed in U.S. Patent 5,053,148. Therefore, simple phosphonic acid salts are unsuitable for use in many polymers that are processed, or subsequently exposed, to high temperatures, such as 250 °C, 260 °C, 270 °C or higher, because at such temperatures they undergo a chemical transformation through processes that damage the polymer. This can occur during compounding, for example, in an extruder, or while the salt is present in a polymer in a high-temperature application. On the other hand, U.S. Patent 9,745,449 discloses that heating a phosphonic acid salt to sufficiently high temperatures, generally in the absence of other materials, thermally transforms the salt into a different, more thermally stable material that exhibits excellent flame-retardant activity when incorporated into polymer substrates. Thermally transformed materials do not degrade at high temperatures, nor do they cause polymer degradation, when processed into polymer compositions at elevated temperatures, for example, 240°C, 250°C, 260°C, 270°C or higher. This is a significant advantage over previously known phosphonate salts, which exhibit flame-retardant activity but frequently degrade the polymer during processing. Thermally transformed materials are described as comprising one or more compounds represented by the QpL / nn / Lznz / e / YiAi empirical formula (IV): arunn / Lznz / e / YiAi where R is alkyl or aryl, M is a metal, q is a number from 1 to 7, for example, 1, 2 or 3, r is a number from 0 to 5, for example, 0, 1 or 2, y is a number from 1 to 7, for example, from 1 to 4, and n is 1 or 2, on condition that 2(q)+r = n(y). However, challenges are encountered with the process and materials of U.S. Patent 9,745,449, such as the production of a product generally in the form of a solid mass that requires crushing, grinding, or other such physical processing before use; the formation of product mixtures containing water-soluble or thermally unstable compounds; and the difficulty in controlling the phosphorus-to-metal ratio of the resulting product. Furthermore, the Examples in U.S. Patent 9,745,449 describe the multi-stage production of a phosphorus-containing flame retardant in which an intermediate metal salt of phosphonic acid is produced, and the dried salt is then heated to temperatures above 200 °C. This disclosure addresses the challenges identified above, while producing a phosphorus-containing flame retardant without requiring the production or use of the intermediate salt as described in U.S. Patent 9,745,449. SUMMARY According to this disclosure, a phosphorus-containing flame retardant is produced by a process comprising reacting at a reaction temperature a mixture comprising a suitable metal or metal compound and a stoichiometric excess with respect to the suitable metal or metal compound of an unsubstituted or alkyl or aryl-substituted phosphonic acid, wherein: The metal is capable of forming a polycation (i.e., a metal represented in its corresponding cationic form by the formula M(+)y where M is a metal, (+)y represents the charge of the metal cation, and ey is 2 or more), or the appropriate metallic compound is represented by the formula Mp(+)yXq where M is a metal, (+)y represents the charge of the metal cation, and ey is 2 or more, X is an anion, and the values ​​of pyq provide a balanced-charge metallic compound; the molar ratio of unsubstituted or alkyl or aryl substituted phosphonic acid to the suitable metal or metallic compound in the mixture is greater than 4:1; the reaction temperature is 105 °C or higher; and the unsubstituted or alkyl or aryl substituted phosphonic acid is in a molten state at the reaction temperature. A process for producing a phosphorus-containing flame retardant is also disclosed, comprising reacting at a reaction temperature a mixture comprising a suitable metal or metal compound and a stoichiometric excess of an unsubstituted or alkyl or aryl-substituted pyrophosphonic acid, wherein: The metal is capable of forming a polycation (i.e., a metal represented in its corresponding cationic form by the formula M<+>y as above), or the suitable metallic compound is represented by the formula MpWyXq where M is a metal, (+)y represents the charge of the metallic cation, and is 2 or more, X is an anion, and the values ​​of pyq provide a balanced-charged metallic compound; The molar ratio of unsubstituted or alkyl or aryl substituted pyrophosphonic acid to the suitable metal or metal compound in the mixture is greater than 2:1; and the unsubstituted or alkyl or aryl substituted pyrophosphonic acid is in a molten state at the reaction temperature. In the process described herein, unsubstituted or alkyl- or aryl-substituted phosphonic or pyrophosphonic acid, used in stoichiometric excess as described herein, acts as both the reactant and solvent for the reaction. Frequently, the reaction product forms as a suspension as the flame retardant product resulting from the present invention precipitates from the reaction mixture. The excess phosphonic or pyrophosphonic acid remaining after the reaction can be removed, along with any possible byproducts, by filtration and / or washing, for example, with water. In many embodiments, a substantially pure flame retardant material is produced, for example, a flame retardant comprising essentially a single compound with flame-retardant activity or essentially a mixture of Qrunn / Lznz / e / YiAi active compounds. The conversion based on the metal or metal compound is usually high, and the product can be easily isolated and, optionally, further purified if desired. The present process overcomes the difficulties observed in processes such as those found in U.S. Patent 9,745,449 because, for example, the production of water-soluble or thermally unstable compounds is reduced or avoided, and the flame retardant product, which normally crystallizes as a powder or small particles, can be produced directly in an easily processable form, i.e., without the need for crushing, granulation, or other such physical processing. Additionally, in many embodiments, the resulting flame retardant material produced according to this disclosure has a higher phosphorus-to-metal ratio than that observed with simple metal phosphonates, as further explained herein.High phosphorus-to-metal ratios in the produced flame retardant lead to greater efficiency and, therefore, may allow for lower loading levels when the flame retardant material forms thermoplastic compounds. Further embodiments of this disclosure include, but are not limited to, a process for preparing a phosphorus-containing flame retardant, comprising reacting a suitable metal or metal compound at a reaction temperature with a molar excess of an unsubstituted or alkyl- or aryl-substituted phosphonic acid, wherein the reaction temperature is approximately 150°C or higher, the unsubstituted or alkyl- or aryl-substituted phosphonic acid is in a molten state at the reaction temperature, and the molar ratio of the unsubstituted or alkyl- or aryl-substituted phosphonic acid to the suitable metal or metal compound is greater than 4:1. In one embodiment, the reaction temperature ranges from approximately 150°C to approximately 300°C, such as from approximately 150°C to approximately 280°C, from approximately 160°C to approximately 260°C, or from approximately 160°C to approximately 220°C.In one embodiment, the molar ratio of unsubstituted or alkyl- or aryl-substituted phosphonic acid to the suitable metal or metal compound ranges from approximately 5:1 to approximately 30:1. In one embodiment, the suitable metal compound is a metal oxide, halide, alkoxide, hydroxide, carboxylate, or phosphonate. QpL / nn / Lznz / e / YiAi suitable metallic compound is alumina, aluminum trichloride, aluminum trihydroxide or aluminum isopropoxide. Other embodiments include, but are not limited to, a phosphorus-containing flame retardant produced according to a process disclosed herein; a flame-retardant polymer composition comprising (i) a polymer and (ii) a phosphorus-containing flame retardant of this disclosure; a process for improving the flame retardancy of a polymer by incorporating a flame retardant of this disclosure into the polymer; and a process for incorporating a flame-retardant composition comprising a flame retardant of this disclosure into a polymer. The foregoing summary is not intended to restrict in any way the scope of the claimed invention. Furthermore, it should be understood that both the preceding general description and the following detailed description are for illustrative and explanatory purposes only and are not restrictive of the invention as claimed. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows the result of the thermogravimetric analysis (TGA) of an example flame retardant material produced in accordance with Example 1 of this disclosure. DETAILED DESCRIPTION Unless otherwise specified, the word "a" or "an" in this application means one or more than one. The term alkyl in this application includes arylalkyl, unless the context dictates otherwise. The term "arilo" in this application includes "alquilarilo", unless the context dictates otherwise. The term phosphonic acid, as used herein, refers to phosphonic acid that is either unsubstituted or substituted with alkyl or aryl, unless the context dictates otherwise. The term pyrophosphonic acid, as used herein, refers to unsubstituted or alkyl or aryl substituted pyrophosphonic acid, unless the context dictates otherwise. As used herein, stoichiometric excess of unsubstituted or alkyl or aryl substituted phosphonic or pyrophosphonic acid with respect to QpL / nn / Lznz / e / YiAi Suitable metal or metal compound refers to an amount of phosphonic or pyrophosphonic acid that exceeds the amount stoichiometrically required for the reaction between the suitable metal or metal compound and the phosphonic or pyrophosphonic acid. The stoichiometric excess is normally represented by a molar ratio of phosphonic or pyrophosphonic acid to the suitable metal or metal compound in the reaction mixture, as described herein. According to one aspect of this disclosure, a suitable metal or metal compound and a stoichiometric excess of unsubstituted or alkyl- or aryl-substituted phosphonic acid are reacted to form a phosphorus-containing flame retardant. The reaction temperature is 105°C or higher, the phosphonic acid is in a molten state at the reaction temperature, and the molar ratio of phosphonic acid to the suitable metal or metal compound in the reaction mixture is greater than 4:1. In the reaction, the metal is oxidized and can be represented in its corresponding cationic form by the formula where M is a metal, (+)y represents the charge of the metal cation, and ey is 2 or more. The suitable metal compound can be represented by the formula MpWyXq, where M is a metal, (+)y represents the charge of the metal cation, and ey is 2 or more, X is an anion, and the values ​​of pyq provide a balanced-charge metal compound. In another aspect, a suitable metal or metallic compound, as previously described, and a stoichiometric excess of unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid are reacted to form a phosphorus-containing flame retardant. The pyrophosphonic acid is in a molten state at the reaction temperature, and the molar ratio of pyrophosphonic acid to the suitable metal or metallic compound in the reaction mixture is greater than 2:1. In many embodiments, the molar ratio of phosphonic acid to the suitable metal or metal compound in the reaction mixture is 5:1 or more, such as approximately 6:1 or more, approximately 8:1 or more, or approximately 10:1 or more. Larger molar excesses of phosphonic acid to the suitable metal or metal compound in the reaction mixture may be used, such as approximately 12:1 or more, approximately 15:1 or more, approximately 20:1 or more, approximately 25:1 or more, approximately 30:1 or more, or any intermediate range. A large molar excess of phosphonic acid to the suitable metal or metal compound may be used. For example, the molar ratio can be up to approximately 50:1, up to approximately 100:1, up to approximately 300:1, up to approximately 500:1, or any intermediate range. However, as might be understood, the efficiency of the process can be affected at certain large molar excesses; for example, precipitation of the product in the reaction mixture may be hindered. In many embodiments, the molar ratio varies from approximately 8:1, approximately 10:1, approximately 12:1, or approximately 16:1 to approximately 100:1 or to approximately 50:1, such as from approximately 10:1, approximately 15:1, or approximately 20:1 to approximately 50:1 or to approximately 40:1. In many embodiments, the molar ratio of pyrophosphonic acid to the suitable metal or metal compound in the reaction mixture is 3:1 or more, such as approximately 4:1 or more, approximately 6:1 or more, or approximately 8:1 or more. Larger molar excesses of pyrophosphonic acid to the suitable metal or metal compound in the reaction mixture are frequently used, such as approximately 10:1 or more, approximately 12:1 or more, approximately 15:1 or more, approximately 18:1 or more, approximately 20:1 or more, or any intermediate range. A large molar excess of pyrophosphonic acid to the suitable metal or metal compound may be used. For example, the molar ratio may be up to approximately 30:1, up to approximately 50:1, up to approximately 100:1, up to approximately 250:1, or any intermediate range.However, as might be expected, the efficiency of the process can be affected at certain large molar excesses; for example, product precipitation in the reaction mixture may be hindered. In many embodiments, the molar ratio varies from approximately 4:1, approximately 5:1, approximately 6:1, or approximately 8:1 to approximately 50:1 or approximately 25:1, such as from approximately 5:1, approximately 8:1, or approximately 10:1 to approximately 25:1 or approximately 20:1. The reaction temperature for producing a phosphorus-containing flame retardant according to this disclosure must be chosen so that the phosphonic or pyrophosphonic acid is in a molten state at the reaction temperature. For example, phosphonic and pyrophosphonic acids (e.g., the Alkyl-substituted phosphonic or pyrophosphonic acids are frequently solids at room temperature (e.g., methylphosphonic acid melts at approximately 105°C and ethylphosphonic acid melts at approximately 62°C), and therefore heating the phosphonic or pyrophosphonic acid to a liquefied (i.e., molten) state is generally appropriate to form a consistent reaction mixture. As a person skilled in the art will appreciate, the desired reaction temperature at which the phosphonic or pyrophosphonic acid is in a molten state can vary depending on the chosen reagents and thermodynamic conditions. The reaction temperature must also be chosen to facilitate the formation of monoanionic and / or dianionic pyrophosphonic acid ligands in the reaction product. For phosphonic acid, a reaction temperature of 105 °C or higher is used. Not bound by any particular theory, the reaction temperature is chosen to produce pyrophosphonic acid ligands through dehydration reactions. In many embodiments, the suitable metal or metal compound and phosphonic acid react at temperatures above 105 °C, such as approximately 115 °C or higher, or approximately 120 °C. QpL / nn / Lznz / e / YiAi or more, approximately 130°C or more, approximately 140°C or more, approximately 150 °C or higher, approximately 160 °C or higher, approximately 170 °C or higher, approximately 180 °C or higher, approximately 200 °C or higher, approximately 220 °C or higher, approximately 240 °C or higher, approximately 260 °C or higher, approximately 280 °C or higher, or any intermediate range. The reaction temperature may be higher than those described above, such as up to approximately 350 °C, up to approximately 400 °C, or higher, but it does not normally reach or exceed the boiling point of phosphonic acid. For example, the reaction temperature may vary from approximately 150 °C to approximately 300 °C, such as from approximately 150 °C to approximately 280 °C, from approximately 160 °C to approximately 260 °C, or from approximately 160 °C to approximately 240 °C. In many embodiments, the reaction temperature varies from approximately 110 °C to approximately 350 °C, from approximately 115 °C to approximately 300 °C, from approximately 125 °C to approximately 280 °C, or from approximately 140 °C to approximately 260 °C. Through the dehydration reaction or reactions, water is formed, which can potentially lead to the unwanted reverse reaction (hydrolysis).Therefore, in some embodiments, the reaction system is designed to facilitate the removal, such as continuous removal, of water from the reaction. For example, the reaction temperature may be chosen above the boiling point of water to the extent necessary to remove by boiling at least a portion or the desired amount (e.g., most, substantially all, or all) of the water from the reaction. Additional means, such as gas purging, vacuum, and / or other known means, may be used to facilitate the removal of water from the reaction system. Since dehydration is unnecessary for pyrophosphonic acid, the reaction temperature for pyrophosphonic acid can be lower than that described above for phosphonic acid. Generally, the limiting criterion for choosing a suitable reaction temperature when using pyrophosphonic acid is the requirement that the pyrophosphonic acid be in a molten state at the reaction temperature. Frequently, the suitable metal or metal compound and pyrophosphonic acid are reacted at a temperature of 20 °C or higher. In many embodiments, the suitable metal or metal compound and pyrophosphonic acid react at temperatures above 20 °C, such as approximately 40 °C or higher, approximately 60 °C or higher, approximately 80 °C or higher, approximately 100 °C or higher, approximately 140 °C or higher, approximately 180 °C or higher, approximately 200 °C or higher, or any intermediate range.The reaction temperature may be higher than those described above, such as up to approximately 300 °C, up to approximately 400 °C, or higher, but it does not normally reach or exceed the boiling point of pyrophosphonic acid. In many embodiments, the reaction temperature varies from approximately 25 °C to approximately 350 °C, from approximately 25 °C to approximately 280 °C, from approximately 30 °C to approximately 260 °C, from approximately 40 °C to approximately 260 °C, from approximately 60 °C to approximately 260 °C, from approximately 80 °C to approximately 240 °C, from approximately 100 °C to approximately 240 °C, from approximately 110 °C to approximately 240 °C, or from approximately 120 °C to approximately 240 °C, depending, for example, on the compound. When a metallic QpL / nn / Lznz / e / YiAi is used to react with pyrophosphonic acid, water may be generated from the reaction. As described above, in some embodiments, the reaction system is designed to facilitate the removal, such as continuous removal, of water from the reaction. For example, the reaction temperature may be chosen above the boiling point of water to the extent necessary to remove by boiling at least a portion or the desired amount (e.g., most, substantially all, or all) of the water from the reaction. Additional means, such as gas purging, vacuum, and / or other known means, may be used to facilitate the removal of water from the reaction system. Often, as the reaction progresses, the product forms as a suspension as the resulting flame retardant precipitates from the reaction mixture. Therefore, the reaction is typically run for a sufficient time to achieve this precipitation. In general, the amount of time required to achieve at least substantial conversion to the flame retardant product, based on the appropriate metal or metal compound, will depend on the reaction temperature, with higher temperatures generally resulting in shorter reaction times.In many embodiments, the suitable metal or metal compound and phosphonic or pyrophosphonic acid are heated to the reaction temperature for approximately 0.1 to approximately 48 hours, such as from approximately 0.2 to approximately 36 hours, from approximately 0.5 to approximately 30 hours, from approximately 1 hour to approximately 24 hours, for example, from approximately 1 hour to approximately 12 hours, from approximately 1 hour to approximately 8 hours, or from approximately 2 hours to approximately 5 hours, although other durations may be used. The suitable metal or metal compound and the molar excess of phosphonic or pyrophosphonic acid can be combined in any manner suitable for forming the reaction mixture. For example, the phosphonic or pyrophosphonic acid and the metal or metal compound can be mixed together (e.g., stirred) to form a homogeneous reaction mixture. In some embodiments, the suitable metal or metal compound is added to phosphonic or pyrophosphonic acid that has been preheated to the reaction temperature. In some embodiments, the phosphonic or pyrophosphonic acid is preheated and stirred after melting, such as in a nitrogen atmosphere or under reduced pressure / vacuum. In other embodiments In addition to the metal or metal compound, the metal is added as quickly as possible without causing a large change in the reaction temperature due to the exothermic nature of the reaction. In some embodiments, the phosphonic or pyrophosphonic acid and the suitable metal or metal compound are combined without preheating the phosphonic acid, or without sufficient heating to liquefy the phosphonic or pyrophosphonic acid, and the components are subsequently heated to the reaction temperature. The total amount of the suitable metal or metal compound or phosphonic or pyrophosphonic acid can be added to the reaction all at once or in portions. No additional solvents are required, as the phosphonic or pyrophosphonic acid, used in a molar excess, acts as both reactant and solvent, but additional solvent may be used if desired.In some embodiments, additional solvent is used when employing molar ratios of phosphonic or pyrophosphonic acid with respect to the suitable metal or metal compound that are at or near the lower limit of the molar ratios disclosed herein. In some embodiments, after the desired conversion, for example, total or substantially total conversion to the flame retardant product, is achieved, the product reaction mixture is cooled to a temperature above or no lower than the melting point of the excess phosphonic or pyrophosphonic acid to maintain the excess phosphonic or pyrophosphonic acid in a liquefied state. The excess phosphonic or pyrophosphonic acid can be removed by filtration / washing and, optionally, recovered. The recovered excess phosphonic or pyrophosphonic acid can be recycled, for example, back to the reactor in which a suitable metal or metal compound reacts with the phosphonic or pyrophosphonic acid. After conversion to the reaction product, a solvent, for example, water, an alcohol, and / or another suitable (e.g., polar) liquid, can optionally be added to dissolve or otherwise assist in the removal of the excess phosphonic or pyrophosphonic acid.The flame retardant product is frequently isolated by filtration, optionally followed by further treatment (e.g., washing, drying, screening, etc.). The resulting flame retardant product, which is generally in the form of a powder or small particles, is easily processable, meaning that crushing, grinding, or other such physical processing is not required or necessary before use. It should be understood that the production of the flame retardant material directly in powder form or... The small particle size distribution process disclosed herein allows for the treatment of the reaction product, such as isolating the flame retardant product (e.g., separating the flame retardant product from excess phosphonic or pyrophosphonic acid or the remaining solvent). This may include, for example, processing the reaction product by filtration, screening, washing, drying, and the like. After the reaction, the resulting product reaction mixture, often a suspension, can be cooled to or just above the melting point of the excess phosphonic acid, and the suspension can be combined with water. The water / suspension mixture can be stirred as needed to break up any large lumps that may have formed.The solid product can be isolated by filtration; optionally, it can be washed with water and dried to produce a powder or small particle form. In some cases, the product can be sieved to refine the particle size. The process described herein produces a flame retardant comprising one or more metals and one or more mono- and / or bidentate pyrophosphonic acid ligands. In some embodiments, compounds may be produced that further comprise phosphonate ligands, but in all embodiments, compounds comprising a monoanionic pyrophosphonic acid ligand and / or a dianionic pyrophosphonic acid ligand are obtained. The process can produce mixtures of flame-retardant compounds, but in many embodiments, the process yields a flame-retardant material as a compound, or predominantly one, with a high conversion based on the metal or metal compound, such as at least 70%, 80%, 85%, 90%, 95%, 98% or more, or any intermediate range, unlike the mixtures of compounds obtained by prior art processes involving the heat treatment of metal phosphonate salts. In a general embodiment, in which phosphonate ligands may be present in the flame-retardant product, the reaction generally proceeds as shown: QpL / nn / Lznz / e / YiAi QpL / nn / Lznz / e / YiAi where M is a metal cation and (+)y represents the charge of the cation, e.g., M is a di-, tri-, tetra-, or pentacationic metal; X is an anionic ligand or ligands bonded to the metal, and the stoichiometry of M and X (i.e., pyq) gives a balanced charge compound; R is H, an alkyl, aryl, alkylaryl, or arylalkyl group; a, b, and c and d represent the ratio of the corresponding components to each other in the reaction product; e and a, b, and c and d are values ​​that give a balanced charge product, provided that y is 2 or more and only one of a and c can be 0 (often, c is not zero). In some embodiments, the phosphonic acid ligand above with coefficient d, when present, may be present as a dianion. In many embodiments, d is 0. In a further aspect, a flame retardant product produced in accordance with this disclosure, normally in the form of a powder or small particles, comprises a compound or a mixture of different compounds of empirical formula (II) where R is H, an alkyl, aryl, alkylaryl or arylalkyl group, a, b, c and d represent the ratio of the corresponding components to one another in the compound, ya is generally a number from 0 to 8, for example, 0 to 6, 0 to 4, or 0 to 2, c is generally a number from 0 to 10, for example, 0 to 8, 0 to 6, 0 to 4 or 0 to 2, d is generally a number from 0 to 6, for example, 0 to 4 or 0 to 2, M is a metal, and y is a number from 2 to 5, such as 2, 3 or 4, frequently 2 or 3, and M(+)y is a metallic cation where (+)y represents the charge formally assigned to the cation. The values ​​of a, b, c, d, and y can vary, but they will satisfy the charge equilibrium equation 2(a)+c+d=b(y), and only one of aoc can be 0. In many embodiments, c is not zero. In cases where a dianionic phosphonic acid ligand is present in the compound, the charge equilibrium equation becomes 2(a)+c+d+2(d)=b(y).The value for b is only limited in that it must satisfy the above equations, but in many embodiments b is a number from 1 to 4, e.g., 1 or 2. In some embodiments, a is 0, 1 or 2 (e.g., 0 or 1), c is 1 or 2, and d is 0, 1 or 2 (e.g., 0 or 1), and the product has balanced load. In many implementations, d is 0, as in: QpL / nn / Lznz / e / YiAi where R, M, y, a, b and c are as described above and the product load balance equation becomes 2(a)+c=b(y). Often, c in formulas (II) and (III) above is not zero (for example, c is from 1 to 10, from 1 to 8, from 1 to 6, from 1 to 4, or 1 or 2). According to the process disclosed herein, it was surprisingly discovered in many embodiments, such as when employing dicationic or tricationic metals, that a flame retardant compound is produced in which c in the above formulas is not zero and the product has a more favorable ratio of phosphorus atoms to metal atoms (i.e., P to M) for providing flame retardancy compared to phosphorus-containing flame retardants described in the art. For example, tricationic metals (e.g., aluminum) and dicationic metals (e.g., zinc) are known to form trisubstituted and disubstituted balanced charge compounds, respectively.As noted in the art, aluminum triphosphonate salts having a phosphorus-to-aluminum ratio of 3:1 and zinc diphosphonate salts having a phosphorus-to-zinc ratio of 2:1 are known as flame retardants. However, according to the pyrophosphonic acid ligand formation process of the present disclosure, and particularly when c in the above formulas is not zero, the phosphorus-to-metal ratio in the flame retardant product is higher. For example, as demonstrated in the Examples disclosed herein, when the process of the present disclosure was employed, the phosphorus-to-aluminum ratio, or the phosphorus-to-iron ratio, in the resulting flame retardant product was 4:1.A higher phosphorus-to-metal ratio leads to high efficiency and can allow reduced loadings when forming thermoplastic polymer compounds. In certain specific embodiments, and in formula (III) is 2 (i.e., M(+)y is a dicationic metal, as described herein), a is 0, b is 1, and c is 2. In certain embodiments, the dicationic metal M is Mg, Ca, or Zn. In other embodiments, and in formula (III) is 3 (i.e., M<+>y is a tricationic metal, as described herein), a is 1, b is 1, and c is 1. In certain embodiments, the tricationic metal M is selected from Al, Ga, Sb, Fe, Co, B, and B. In certain embodiments, the tricationic metal M is Al, Fe, Ga, Sb, or B. As is usual with inorganic coordination compounds, the reaction product in the reaction described above and the compounds of empirical formulas (II) and (III) are idealized so that the reaction product or compounds may include coordination polymers, complex salts, salts where certain atomic valencies are shared, etc. For example, in many embodiments, empirical formula (II) or (III) represents a monomeric unit (i.e., a coordination entity) of a coordination polymer, thereby forming the extended coordination polymer structure of the flame retardant compound of the present disclosure. In one example, where M is Al and ey is 3, a compound of empirical formula (III) is produced according to the following empirical formula (llia): QpL / nn / Lznz / e / YiAi L ~ JLJLJ (Illa). As shown herein, the absence of the subscripts a, b, and c in the empirical formulas indicates that the subscripts are each 1, signifying a 1:1:1 ratio of the components (in the case of empirical formula (Illa), a 1:1:1 ratio of dianionic pyrophosphonic acid ligand, metal atom, and monoanionic pyrophosphonic acid ligand). In this example, empirical formula (llia) represents a repeating monomeric unit (i.e., a coordination entity) of a coordination polymer, thereby forming the extended coordination polymer structure of the flame retardant compound of this disclosure. Frequently, a compound of empirical formula (II) or (III), which in many embodiments is an extended coordination polymer as described herein, constitutes all, substantially all, or at least most of the flame retardant product, such as at least 75%, 85%, 90%, 95%, 98%, or more, or any intermediate range, by weight of the flame retardant product. A compound of empirical formula (II) or (III) (e.g., (Illa)) can be produced with a high conversion based on the metal or metal compound, such as at least a conversion of 70%, 80%, 85%, 90%, 95%, 98% or more, e.g., a conversion of at least 70% to 95%. In some of these embodiments, M is aluminum (i.e., the reaction product is produced using aluminum or one or more aluminum compounds, such as those described herein) or iron (i.e., the reaction product is produced using iron or one or more iron compounds, such as those described herein). The phosphonic acid used in the present process can be represented by the formula (I) or QpL / nn / Lznz / e / YiAi where R is H, alkyl, aryl, alkylaryl, or arylalkyl. In many embodiments, R is H, C1-12 alkyl, Ce-io aryl, C7-18 alkylaryl, or C7-18 arylalkyl, wherein said alkyl, aryl, alkylaryl, or arylalkyl is unsubstituted or substituted with halogen, hydroxyl, amino, C1-4 alkylamino, C1-4 dialkylamino, C1-4 alkoxy, carboxy, or C2-5 alkoxycarbonyl. In some embodiments, said alkyl, aryl, alkylaryl, or arylalkyl is unsubstituted C1-12 alkyl, Ce-io aryl, C7-10 alkylaryl, or C7-10 arylalkyl, for example, C1-6 alkyl, phenyl, or C7-9 alkylaryl. In some embodiments, R is a substituted or unsubstituted C1-6 alkyl, Ce aryl, C7-10 alkylaryl, or C7-12 arylalkyl, for example, C1-4 alkyl, Ce aryl, C7-9 alkylaryl, or C7-10 arylalkyl. In many embodiments, R is an unsubstituted alkyl, for example, a C1-6 alkyl.In many embodiments, lower alkyl phosphonic acids are used, for example, methyl-, ethyl-, propyl-, isopropyl-, butyl-, t-butyl- and the like. R as alkyl can be a linear or branched alkyl group having the specified number of carbons and includes, for example, unbranched alkyls such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and branched alkyls such as isopropyl, isobutyl, sec-butyl, t-butyl, ethyl, hexyl, t-octyl, and the like. For example, R as alkyl can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and t-butyl. In many embodiments, R is methyl, ethyl, propyl, or isopropyl, e.g., methyl or ethyl. Often, when R is aryl, it is phenyl. Examples of R as alkylaryl include phenyl substituted with one or more alkyl groups, for example, groups selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, and the like. Examples of R as arylalkyl include, for example, benzyl, phenethyl, styryl, cumyl, phenpropyl, and the like. In many embodiments, R is chosen from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl. The pyrophosphonic acid used in the present process can be represented by the formula (la): either RH P--OH / EITHER \ R-[¡-OH Or (la), where R is the same as that revealed above for formula (I)· The general reaction scheme with a pyrophosphonic acid and a suitable metal compound can be represented as: Qrunn / Lznz / e / YiAi QpL / nn / Lznz / e / YiAi where R, M, X, p, q, y, a, b and c are as described herein. The process described herein may employ more than one phosphonic acid, more than one pyrophosphonic acid, or a combination of phosphonic and pyrophosphonic acids, provided that the mixture of phosphonic and / or pyrophosphonic acids is in a molten state at the reaction temperature. In some embodiments, the phosphonic or pyrophosphonic acid is generated in situ. For example, phosphonic or pyrophosphonic acid may be prepared, such as by hydrolysis of starting materials of higher oligomeric phosphonic acid and / or cyclic phosphonic acid anhydride. As used herein, suitable metallic compound and the like refer to a compound of formula Mp(+>yxq); where M is a metal capable of forming a polycation, e.g., a metal that forms a 2+, 3+, 4+, or 5+ cation, typically 2+, 3+, or 4+, and X is any anion that provides a balanced-charge compound with metal M. Suitable examples of X include, but are not limited to, anions that, together with metal M, form oxides, halides, alkoxides, hydroxides, carbonates, carboxylates, and phosphonates. Values ​​of p and q provide a balanced-charge metallic compound, e.g., alumina, Al₂O₃. In some embodiments, an unsubstituted metal, M, is used as described herein. Some examples of suitable metals (M) include, but are not limited to, Mg, Ca, Ba, Zn, Zr, Ge, B, Al, Si, Ti, Cu, Fe, Co, Ga, B, Mn, Sn or Sb. In some realizations, M is chosen from Mg, Ca, Ba, Zn, Zr, Ga, B, Al, Si, Ti, Cu, Fe, Sn or Sb.In some embodiments, M is chosen from Mg, Ca, Ba, Zn, Zr, B, Al, Si, Ti, Fe, Sn or Sb, for example, M can be Mg, Zn, Ca, Fe or Al. Suitable metal compounds include, but are not limited to, compounds having a metal-oxygen bond, metal-nitrogen bond, metal-halogen bond, metal-hydrogen bond, metal-phosphorus bond, metal-sulfur bond, metal-boron bond, etc., for example, oxides, halides, alkoxides, hydroxides, carboxylates, carbonates, phosphonates, phosphines, phosphonites, phosphates, phosphites, nitrates, nitrites, borates, hydrides, sulfonates, sulfates, sulfides, etc., of Mg, Ca, Ba, Zn, Zr, Ge, B, Al, Si, Ti, Cu, Fe, Co, Ga, B, Mn, Sn or Sb, for example, oxides, hydroxides, halides or alkoxides of Mg, Ca, Ba, Zn, Zr, Ga, B, Al, Si, Ti, Cu, Fe, Sn or Sb; such as oxides, hydroxides, halides or alkoxides of Mg, Ca, Ba, Zn, Zr, B, Al, Si, Ti, Fe, Sn or Sb, for example, oxides, hydroxides, halides or alkoxides of Mg, Zn, Ca, Fe or Al. In some embodiments, the metal, M, of the suitable metal or metallic compound is aluminum or iron. In some embodiments, the suitable metallic compound is selected from aluminum halides, oxides, hydroxides, alkoxides, carbonates, carboxylates, and phosphonates. In some embodiments, the suitable metallic compound is selected from aluminum halides, oxides, hydroxides, and alkoxides. In some embodiments, the suitable metallic compound is selected from alumina, aluminum trichloride, aluminum trihydroxide, aluminum isopropoxide, aluminum carbonate, and aluminum acetate. In other embodiments, the suitable metallic compound is selected from iron halides, oxides, alkoxides, carbonates, and acetates. In some embodiments, the suitable metallic compound is selected from iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, and iron(III) acetate. In certain embodiments, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al, Fe, Zn, or Ca. In additional embodiments, X is oxygen, hydroxy, alkoxy, or halogen. The reaction described in this document can be performed, but not necessarily, at reduced pressure or under vacuum. The product reaction mixture formed from the reaction described herein, which is frequently in the form of a suspension, can be combined with a liquid (e.g., water) and stirred as desired to break up any lumps that may have formed. The solid product can be isolated by filtration and, optionally, washed and dried to produce the product in the form of a powder or small particles. In some cases, the product can be sieved to refine the particle size. The reaction described herein can be optionally facilitated with a seeding material. For example, the use of a seeding material can reduce the time required to achieve conversion to the flame retardant product and can lead to greater uniformity in the product's physical characteristics. Often, the seeding material is QpL / nn / Lznz / e / YiAi is added to the reaction mixture upon heating to or after the reaction temperature. In some embodiments, the seeding material comprises a flame retardant material produced according to the process of this disclosure, such as a flame retardant compound of empirical formula (II), (III), or (IIIa) as described herein. The seeding material may be selected or refined to have a desired particle size. In some embodiments, the suitable metallic compound is alumina, and the flame retardant material is produced as follows: QpL / nn / Lznz / e / YiAi In one example, a phosphonic acid, such as a C1-C12 alkyl phosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or t-butyl phosphonic acid), is heated to or above its melting point, 105 °C, such as to 115 °C, 125 °C, 140 °C, 150 °C, 160 °C, 180 °C, 200 °C, 220 °C, or 240 °C or higher, with stirring (e.g., in nitrogen) after melting. An oxide, hydroxide, halide, alkoxide, carbonate, or carboxylate of aluminum, such as alumina, aluminum trichloride, aluminum trihydroxide, aluminum isopropoxide, aluminum carbonate, or aluminum acetate, is added with stirring to a stoichiometric excess of phosphonic acid, such as a molar ratio of phosphonic acid to the metal compound as described herein, for example, 5:1 or more, 10:1 or more, or 15:1 or more. Typically, a suspension forms as the reaction proceeds, and the solid flame retardant product can be isolated, such as by filtration, washing, etc.to produce the product in the form of a powder or small particles. Further treatment of the product reaction mixture may be carried out before isolating the solid product, such as cooling the product reaction mixture above, or at least below, the melting point of the excess phosphonic acid, and combining it with a liquid, for example, water, and optionally stirring as described above. The solid flame retardant product may be isolated by filtration, optionally washed with additional solvent and dried, to produce the product in the form of a powder or small particles. The flame retardant product contains phosphorus and aluminum in a 4:1 ratio according to the following empirical formula: Γ ,·> p íoI * I || : í ____ : O < i '''5u“'· In a further example, the example described directly above is carried out with iron or a suitable iron compound, such as iron halides, oxides, alkoxides, carbonates, or acetates, for example, iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, or iron(III) acetate. The flame retardant product contains phosphorus and iron in a 4:1 ratio according to the following empirical formula: QpL / nn / Lznz / e / YiAi Frequently, the compound of the above empirical formulas (which in many embodiments is an extended coordination polymer as described herein) constitutes all, substantially all, or at least most of the flame retardant product, such as at least 75%, 85%, 90%, 95%, 98%, or more, or any intermediate interval, by weight of the flame retardant product. In some embodiments, the suitable metal compound is a metal phosphonate salt. The metal in the metal phosphonate salt may be a metal, M, as described herein. The suitable metal compound may be a metal phosphonate salt of the following formula: where R and M are as described above, p is a number from 2 to 5, for example, 2, 3, or 4, and e is a number from 2 to 5, for example, 2, 3, or 4, such that M(+)y is a metal cation where (+)y represents the charge formally assigned to the cation. Typically, the metal phosphonate salt has a balanced charge (i.e., p=y). The metal phosphonate salt can be prepared according to methods known in the art. In some embodiments, the metal phosphonate salt is prepared from the reaction of a starting metal compound and phosphonic acid with a solvent (e.g., water) for the phosphonic acid. The starting metal compound may be a compound according to the suitable metal compound described herein. In some embodiments, the starting metal compound and phosphonic acid are reacted at or near room temperature or at a temperature ranging from approximately 0 to approximately 20 °C. The resulting metal phosphonate salt may then be used as the suitable metal compound according to the inventive process described herein. For example, a phosphonic acid, such as an alkyl phosphonic acid, e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl phosphonic acid, and a solvent (e.g., water) can be stirred to form a homogeneous solution. Any convenient ratio of water to phosphonic acid can be used, e.g., from 10:1 to 1:10 by weight, more commonly from 5:1 to 1:5, and good results have been obtained using mixtures of 2:1 to 1:2. The solution can be cooled to, e.g., in the range of approximately 0 to approximately 20 °C, and a starting metal compound, such as a metal oxide, halide, alkoxide, or hydroxide, is added to react with the phosphonic acid. A metal phosphonate salt is formed, which is then used as the suitable metal compound according to the process disclosed herein.For example, in a separate reactor, a molar excess of phosphonic acid as described herein (e.g., at a 5:1 molar ratio of phosphonic acid to the metal phosphonate salt) is preheated to a molten state and reacted with the metal phosphonate salt to form the flame retardant product. In embodiments involving an aluminum phosphonate salt as the suitable metal compound, the flame retardant product contains phosphorus and aluminum in a 4:1 phosphorus-to-aluminum ratio according to the following empirical formula: QpL / nn / Lznz / e / YiAi Frequently, the compound of empirical formula arunn / Lznz / e / YiAi (which in many embodiments is an extended coordination polymer as described herein) constitutes all, substantially all, or at least most of the flame retardant product, such as at least 75%, 85%, 90%, 95%, 98%, or more, or any intermediate range, by weight of the flame retardant product. The flame retardant of the invention can be used with a variety of other flame retardants and / or synergistic agents or flame retardant adjuvants as known in the art. For example, the flame retardant of the invention can be formulated with one or more materials selected from: carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes; polyphenylene ether (PPE), phosphine oxides and polyphosphine oxides, for example, benzyl phosphine oxides, polybenzyl phosphine oxides and the like; melamine, melamine derivatives and melamine condensation products, melamine salts such as, but not limited to, melamine cyanurate, melamine borate, melamine phosphates, melamine metallic phosphates, melam, melem, melon and the like; inorganic compounds, including clays, metallic salts such as hydroxides, oxides, oxide hydrates, borates, carbonates, sulfates, phosphates, phosphites, hypophosphites, silicates, mixed metallic salts, etc., for example, talc and other magnesium silicates, calcium silicate, aluminosilicate, aluminosilicate in the form of hollow tubes (DRAGONITE), calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, HALLOYSITE or boron phosphate, calcium molybdate, exfoliated vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide and zinc borate, zinc molybdate (or complexes thereof, for example, Kemgard 911B), zinc molybdate / magnesium hydroxide complex (for example, Kemgard MZM), zinc molybdate complex zinc / magnesium silicate (Kemgard 911C), calcium / zinc molybdate complex (e.g., Kemgard 911 A), zinc phosphate (or complexes thereof, e.g., Kemgard 981), magnesium oxide or hydroxide, aluminum oxide,Aluminum oxide hydroxide (Boehmite), aluminum trihydrate, silica, tin oxide, antimony (III and V) oxide hydrate, titanium oxide and zinc oxide or oxide hydrate, zirconium oxide and / or zirconium hydroxide and the like. Unless otherwise specified, in the context of this application, the term phosphate when used as a component in a phosphate salt, such as in metallic phosphate, melamine phosphate, melamine metallic phosphate, etc., refers to a phosphate, hydrogen phosphate, dihydrogen phosphate, pyrophosphate, polyphosphate or an anion or polyanion of phosphoric acid condensation products. Similarly, unless otherwise specified, in the context of this application, the term phosphite when used as a component in a phosphite salt, such as in metallic phosphite, etc., refers to a phosphite or hydrogen phosphite. The flame retardant of the invention can also be formulated with other flame retardants, such as halogenated flame retardants, alkyl or aryl phosphine oxide flame retardants, alkyl or aryl phosphate flame retardants, alkyl or aryl phosphonates, alkyl or aryl phosphinates, and alkyl or aryl phosphinic acid salts. In some embodiments, the flame retardant comprises a mixture of the flame retardant according to the present disclosure and a phosphine salt of the following formula (for example, an aluminum tris(dialkylphosphinate)), Qrunn / Lznz / e / YiAi Ri and R2 can each independently be a group according to R as described herein, M is a metal as described herein (e.g., Al or Ca), and n is a number from 2 to 7, e.g., 2 to 4, frequently 2 or 3. In many embodiments, a flame retardant polymer composition according to this disclosure comprises (i) a polymer, (ii) a flame retardant material of this disclosure, and (ii) one or more additional flame retardants and / or one or more flame retardant synergists or adjuvants. For example, in some embodiments, the flame-retardant polymer composition comprises one or more additional flame retardants, for example, halogenated flame retardants, phosphine oxide flame retardants, alkyl or aryl phosphonates or salts of alkyl or aryl phosphinates, for example, an aluminum tris(dialkylphosphinate) such as aluminum tris(diethylphosphinate). In some embodiments, the flame retardant polymer composition comprises one or more flame retardant synergists or adjuvants, for example, melamine, melamine derivatives and melamine condensation products (for example, melam, melem, melon), melamine salts, phosphine oxides and polyphosphine oxides, metal salts such as hydroxides, oxides, oxide hydrates, borates, phosphates, phosphonates, phosphites, silicates and the like, for example, aluminum hydrogen phosphite, melem or a melamine metal phosphate, for example, a melamine metal phosphate wherein the metal comprises aluminum, magnesium or zinc.In particular embodiments, the one or more flame retardants, synergistic agents or additional flame retardant adjuvants comprise aluminum tris(dialkylphosphinate), aluminum hydrogen phosphite, methylene-diphenylphosphine oxide substituted polyaryl ether, xylenebis(diphenylphosphine oxide), 4,4'-bis(diphenylphosphine methyl)-1,Γ-biphenyl, ethylene bis-1,2-bis-(9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide)ethane, melem, melam, melon or dimelamine zinc pyrophosphate. Certain embodiments provide a halogen-free polymer composition. In such embodiments, halogen-containing flame retardants or synergistic agents would be excluded to the extent possible. The flame retardant material of this disclosure may be combined with an additional flame retardant, synergist, or adjuvant in a ratio of 100:1 to 1:100 by weight of the inventive flame retardant to the total weight of the additional flame retardant, synergist, and / or adjuvant. In some embodiments, the flame retardant material of this disclosure is present in a ratio of 10:1 to 1:10 by weight of the inventive flame retardant to the total weight of the additional flame retardant, synergist, and / or adjuvant, for example, weight ratios ranging from 7:1 to 1:7, 6:1 to 1:6, 4:1 to 1:4, 3:1 to 1:3, and 2:1 to 1:2. The inventive flame retardant is frequently the major component in such a combination, for example, a ratio of 10:1 to 1.2:1 or a ratio of 7:1 to 2:1 by weight of the inventive flame retardant material with respect to the total weight of the flame retardant. QpL / nn / Lznz / e / YiAi flame, additional synergistic agent and / or adjuvant, but the inventive material can also be the minor component of the mixture, for example, a ratio of 1:10 to 1:1.2 or a ratio of 1:7 to 1:2. The thermally stable flame retardant of the invention can form thermoplastic polymer compounds at high temperatures, such as high-temperature polyamides and polyethylene terephthalate esters, without decomposing or adversely affecting the polymer's physical properties, and its flame retardant activity is excellent. The flame retardant of the invention can be used in other polymers, with other synergistic agents, and with conventional polymer additives. The polymer in the flame-retardant composition of the present invention may be any polymer known in the art, such as polyolefin homopolymers and copolymers, rubbers, polyesters (including polyalkylene terephthalates), epoxy resins, polyurethanes, polysulfones, polyimides, polyphenylene ethers, styrenic polymers and copolymers, polycarbonates, acrylic polymers, polyamides, polyacetals, and biodegradable polymers. Mixtures of different polymers may also be used, such as mixtures of polyphenylene ether and styrenic resin, polyvinyl chloride / acrylonitrile butadiene styrene (ABS), or other impact-modified polymers, such as methacrylonitrile and α-methylstyrene containing ABS, and polyester / ABS or polycarbonate / ABS and polyester or polystyrene plus some other impact modifier. These polymers are commercially available or manufactured using methods well known in the art. The flame retardant of the invention is particularly useful in thermoplastic polymers that are processed and / or used at high temperatures, for example, styrenic polymers, including high impact polystyrene (HIPS), polyolefins, polyesters, polycarbonates, polyamides, polyurethanes, polyphenylene ethers, and the like. For example, the polymer may be a polyester resin, a styrenic resin, a polyamide resin, a polycarbonate resin, a polyphenylene oxide resin, a vinyl resin, an olefinic resin, an acrylic resin, an epoxy resin, or a polyurethane. The polymer may be a thermoplastic or a thermosetting resin and may be reinforced, for example, with glass. In some embodiments, the polymer is a thermoplastic polyurethane. QpL / nn / Lznz / e / YiAi is a thermosetting epoxy resin. More than one polymer resin may be present. In particular embodiments, the polymer is an engineered polymer, for example, a thermoplastic or reinforced thermoplastic polymer, for example, a glass-reinforced thermoplastic polymer, such as a glass-filled polyester, optionally an epoxy resin, or a polyamide, for example, a glass-filled polyester, such as a glass-filled polyalkylene terephthalate, or a glass-filled polyamide. Polyester series resins include homopolyesters and copolyesters obtained by, for example, polycondensation of a dicarboxylic acid component and a diol component, and polycondensation of a hydroxycarboxylic acid or a lactone component, for example, aromatic resin of the saturated polyester series, such as polybutylene terephthalate or polyethylene terephthalate. The polyamide (PA) series resins include polyamides derived from a diamine and a dicarboxylic acid; polyamides obtained from an aminocarboxylic acid, if necessary in combination with a diamine and / or a dicarboxylic acid; and polyamides derived from a lactam, if necessary in combination with a diamine and / or a dicarboxylic acid. Polyamide also includes copolyamides derived from at least two different types of polyamide constituents.Examples of resins in the polyamide series include aliphatic polyamides such as PA 46, PA 6, PA 66, PA 610, PA 612, PA 11, and PA 12; polyamides obtained from an aromatic dicarboxylic acid, for example, terephthalic acid and / or isophthalic acid, and an aliphatic diamine, for example, hexamethylenediamine or nonamethylenediamine; and polyamides obtained from both aromatic and aliphatic dicarboxylic acids, for example, both terephthalic acid and adipic acid, and an aliphatic diamine, for example, hexamethylenediamine and others. These polyamides can be used individually or in combination. In some embodiments, the polymer comprises PA 6. In some embodiments, the polymer comprises PA 66. In some embodiments, the polymer comprises a polyphthalamide. Polyamides with melting points of at least 280 °C are widely used to produce molding compositions that enable the production of molded articles, for example, for the electrical and electronics industry, with excellent dimensional stability at high temperatures and with properties QpL / nn / Lznz / e / YiAi are very good flame retardants. Molding compositions of this type are in demand, for example, in the electronics industry for producing components that are mounted on printed circuit boards according to surface mount technology (SMT). In the present application, these components must withstand temperatures up to 270 °C for short periods of time without dimensional changes. These high-temperature polyamides include certain polyamides produced from alkyl diamines and diacids, such as polyamide 4,6. However, many high-temperature polyamides are aromatic and semi-aromatic polyamides—that is, homopolymers, copolymers, terpolymers, or higher polymers derived from monomers containing aromatic groups. A single aromatic or semi-aromatic polyamide may be used, or mixtures of aromatic and / or semi-aromatic polyamides are employed. It is also possible for the aforementioned polyamides and polyamide mixtures to be blended with other polymers, including aliphatic polyamides. Los exemplos de estas poliamidas de temperatura alta aromáticas o semiamáticas incluyen poliamida 4T, poli(m-xylene adipamide) (poliamida MXD,6), poli(dodecamethylene terephthalamide) (poliamida 12,T), poli(decamethylene terephthalamide) (poliamida 10,T), poli(nonamethylene terephthalamide) (poliamida 9,T), copoliamida de hexametileno adipamida / hexametileno tereftalamide (poliamida 6,T / 6,6), copoliamida de hexametileno tereftalamide / 2-metilpentametileno tereftalamide (poliamida 6,T / D,T); copoliamida de hexametileno adipamida / hexametileno tereftalamide / hexametileno isoftalamide (poliamida 6,6 / 6,T / 6,l); poli(caprolactama-hexametileno tereftalamide) (poliamida 6 / 6,T); hexamethylene terephthalamide / hexamethylene isophthalamide copolymer (6,T / 6,I); and similar. Certain embodiments of the invention are, therefore, compositions comprising a polyamide that melts at high temperatures, for example, 280 °C or more, 300 °C or more, in some embodiments 320 °C or more, for example, from 280 to 340 °C, such as polyamide 4,6 and the aromatic and semi-aromatic polyamide described above, articles comprising high-temperature polyamides and the flame-retardant material of the invention, methods for preparing the compositions, and methods for shaping the articles. As described in this document, in many implementations of the According to this disclosure, the flame retardant polymer composition comprises (i) a polymer, (ii) the flame retardant of this disclosure, and (iii) one or more additional flame retardants and / or one or more synergistic agents or flame retardant adjuvants. Therefore, although the flame retardant (ii) alone exhibits excellent activity in polymer systems, it may be used in combination with (iii) one or more compounds selected from other flame retardants, synergistic agents, and adjuvants.Example compounds (iii) include halogenated flame retardants, alkyl or aryl phosphine oxides, alkyl or aryl polyphosphine oxides, alkyl or aryl phosphates, alkyl or aryl phosphonates, alkyl or aryl phosphinates, salts of alkyl or aryl phosphinic acid, carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes, polyphenylene ether, melamine, melamine derivatives, melamine condensation products, melamine salts, metal hydroxides, metal oxides, metal oxide hydrates, metal borates, metal carbonates, metal sulfates, metal phosphates, metal phosphonates, metal phosphites, metal hypophosphites, metal silicates, and mixed metal salts.For example, one or more compounds (iii) may be selected from aluminum tris(dialkylphosphinate), aluminum hydrogen phosphite, benzyl phosphine oxides, polybenzyl phosphine oxides, melam, melem, melon, melamine phosphates, melamine metal phosphates, melamine cyanurate, melamine borate, talc, clays, calcium silicate, aluminosilicate, aluminosilicate in the form of hollow tubes, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, boron phosphate, calcium molybdate, exfoliated vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate, zinc phosphate, magnesium oxide, magnesium hydroxide, aluminum oxide, zinc oxide hydroxide aluminum, aluminum trihydrate, silica, tin oxide, antimony (III and V) oxide, antimony (III and V) oxide hydrate, titanium oxide, zinc oxide, zinc oxide hydrate, zirconium oxide and zirconium hydroxide.For example, one or more compounds (iii) may be selected from aluminum tris(dimethylphosphinate), aluminum tris(diethylphosphinate), aluminum tris(dipropylphosphate), aluminum tris(dibutylphosphinate), polyaryl ether substituted with methylene-diphenylphosphine oxide, xylenebis(diphenylphosphine oxide), 1,2-bis-(9,10-dihydro-9-oxy10-phosphaphenanthrene-10-oxide)ethane, 4,4'-bis(diphenyllphosphinylmethyl)-1,1'-biphenyl, melam, melem, melon, and dimelamine zinc pyrophosphate. In some embodiments, the flame retardant synergistic agent comprises QpL / nn / Lznz / e / YiAi a material selected from melamine, melem, melon, melamine cyanurate, melamine polyphosphate, and melamine-metallic polyphosphate (e.g., melamine-poly(zinc phosphate) (Safire 400)). In some embodiments, the synergistic agent comprises a triazine-based compound, such as a reaction product of trichlorotriazine, piperazine, and morpholine, e.g., poly-[2,4-(piperazin-1,4-yl)-6-(morpholin-4-yl)1,3,5-triazine] / piperazine (MCA® PPM Triazine HF). In some embodiments, the synergistic agent comprises a metallic hypophosphite, such as aluminum hypophosphite (e.g., Italmatch Phoslite® IP-A). In some embodiments, the synergistic agent comprises an organic phosphinate, such as aluminum dialkylphosphinate, for example, aluminum diethylphosphinate (Exolit OP). In some embodiments, the flame retardant polymer composition comprises one or more compounds selected from hydrotalcite clays, metal borates, metal oxides and metal hydroxides, such as metal borates, metal oxides or metal hydroxides where the metal is zinc or calcium. The concentration of the inventive flame retardant in the polymer composition depends, of course, on the exact chemical composition of the flame retardant, the polymer, and other components present in the final polymer composition. For example, when used as the sole flame retardant component of a polymer formulation, the inventive flame retardant may be present at a concentration of 1 to 50%, for example, 1 to 30%, by weight of the total weight of the final composition. Typically, when used as the sole flame retardant, at least 2% of the inventive material will be present, for example, 3% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more. In many embodiments, the inventive flame retardant is present in amounts up to 45%, while in other embodiments, the amount of inventive flame retardant is 40% of the polymer composition or less, for example, 35% or less.When used in combination with other flame retardants or flame retardant synergists, a lesser amount of inventive material may be required. To prepare the flame-retardant polymer composition of this disclosure, any known compounding technique may be used; for example, the flame retardant may be introduced into the molten polymer by mixing, extrusion, fiber or film forming, etc. In some cases, the flame retardant is introduced into the polymer at the time of forming or QpL / nn / Lznz / e / YiAi the curing of the polymer, for example, the flame retardant of the invention can be added to a polyurethane prepolymer before crosslinking or can be added to a polyamine or alkyl-polycarboxyl compound before the formation of the polyamide or to an epoxy mixture before curing. The flame retardant polymer composition of the invention will frequently contain one or more of the common stabilizers or other additives frequently found in the art, such as phenolic antioxidants, hindered amine light stabilizers (HALS), ultraviolet light absorbers, phosphites, phosphonites, alkali metal salts of fatty acids, hydrotalcites, metal oxides, borates, epoxidized soybean oils, hydroxylamines, tertiary amine oxides, lactones, thermal reaction products of tertiary amine oxides, thiosynergistic agents, basic co-stabilizers, e.g., melamine, melem, etc., polyvinylpyrrolidone, dicyandiamide, trialyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, hydrotalcites, alkali metal salts and alkaline earth metal salts of higher fatty acids, for example, Ca stearate, calcium stearoyl lactate, calcium lactate, Zn stearate, Zn octoate, Mg stearate, Na ricinoleate and K palmitate, antimony pyrocatecholate or zinc pyrocatecholate, nucleating agents, clarifying agents, etc. Other additives may also be present, for example, plasticizers, lubricants, emulsifiers, pigments, colorants, optical brighteners, other flame retardants, antistatic agents, blowing agents, anti-drip agents, for example, PTFE and the like. Optionally, the polymer may include fillers and reinforcing agents, such as calcium carbonate, silicates, glass fibers, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, and graphite. These fillers and reinforcing agents are frequently present at relatively high concentrations, including formulations where the filler or reinforcement is present at concentrations exceeding 50% by weight based on the weight of the final composition. More typically, fillers and reinforcing agents are present at approximately 5% to approximately 50% by weight, for example, approximately 10% to approximately 40% by weight or approximately 15% to approximately 30% by weight based on the weight of the total polymer composition. QpL / nn / Lznz / e / YiAi In some embodiments, the flame-retardant polymer composition of this disclosure is formulated with one or more materials selected from carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes, talc, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, calcium silicate, magnesium silicate, aluminosilicate hollow tubes (Dragonite), halloysite, boron phosphate, calcium molybdate, exfoliated vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate (or complexes thereof, e.g., Kemgard 911 B), zinc molybdate / magnesium hydroxide complex (e.g., Kemgard MZM), zinc molybdate / magnesium silicate complex (Kemgard 911C), calcium molybdate / zinc complex (for example, Kemgard 911 A), zinc phosphate (or complexes thereof, for example, Kemgard 981) and the like; hydroxides, oxides and oxide hydrates of (semi)metals of groups 2, 4, 12, 13, 14, 15, for example, magnesium oxide or hydroxide, aluminum oxide, aluminum oxide hydroxide (Boehmite), aluminum trihydrate, silica, silicates, tin oxide, antimony (III and V) oxide and oxide hydrate, titanium oxide and zinc oxide or oxide hydrate, zirconium oxide and / or zirconium hydroxide and the like; melamine and urea-based resins such as melamine cyanurate, melamine borate, melamine polyphosphate, melamine pyrophosphate, polyphenylene ether (PPE) and the like; and clays, including, for example, hydrotalcite, boehmite, kaolin, mica, montmorillonite, wollastonite, nanoclays or organically modified nanoclays and the like. In some embodiments, the flame retardant polymer composition of the present disclosure is formulated with one or more materials selected from zinc borate, zinc stannate, polysiloxanes, kaolin, silica, magnesium hydroxide, zinc molybdate complex (e.g., Kemgard 911B), zinc molybdate / magnesium hydroxide complex (e.g., Kemgard MZM), zinc molybdate / magnesium silicate complex (Kemgard 911C), calcium / zinc molybdate complex (e.g., Kemgard 911 A), zinc phosphate complex (e.g., Kemgard 981) and melamine-poly(metal phosphate) (e.g., melamine-zinc polyphosphate) (Safire 400)). In some embodiments, in addition to a polymer (as described herein) and the flame retardant of this disclosure, the flame retardant polymer composition comprises melamine and one or more QpL / nn / Lznz / e / YiAi selected materials of zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium / zinc molybdate complex, zinc phosphate complex and zinc oxide, optionally with additional additives, as described herein. In some embodiments, in addition to a polymer (as described herein) and the flame retardant of this disclosure, the flame retardant polymer composition comprises melon and one or more materials selected from zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium / zinc molybdate complex, zinc phosphate complex, and zinc oxide, optionally with additional additives, as described herein. The Examples that follow provide additional non-limiting disclosure. EXAMPLES Example 1 QpL / nn / Lznz / e / YiAi A 250 mL three-necked flask was filled with 114.6 g of methylphosphonic acid and heated. At 105 °C, the methylphosphonic acid melted, and vigorous stirring was initiated under a nitrogen atmosphere. The methylphosphonic acid was heated to 240 °C, and 7.78 g of alumina were added as rapidly as possible without causing a large exothermic reaction. The slurry was cooled to just above the melting point of the excess methylphosphonic acid, approximately 110 °C, and then added to 250 mL of water, ensuring that the rate of addition did not cause excessive vapor formation. The resulting mixture was stirred to break up any large clumps that might have formed, the product was isolated by filtration, washed with an additional 750 ml of H2O and dried to produce 45.08 g of the product in the form of fine colorless crystals with a yield of 87%.The empirical formula of the above product represents repeating monomeric units (i.e., coordination entities) of a coordination polymer that forms the pure crystalline product. The thermogravimetric analysis (TGA) of the product is shown in FIG. 1. Example 2 QpL / nn / Lznz / e / YiAi A 250 mL three-necked flask was filled with 149.8 g of ethylphosphonic acid, which was heated to its melting point at 62 °C. Vigorous stirring was initiated under a nitrogen atmosphere, the ethylphosphonic acid was heated to 240 °C, and 6.9 g of alumina were added as rapidly as possible without causing a large exothermic reaction. The suspension was cooled to approximately 80 °C, and then 250 mL of water was added, ensuring that the rate of addition did not cause excessive vapor formation. The resulting mixture was stirred to break up any large lumps that might have formed, the product was isolated by filtration, washed with an additional 750 mL of water, and dried to yield 49.07 g of the product as fine, colorless crystals in an 84% yield. The empirical formula of the above product represents repeating monomeric units (i.e., coordination entities) of a coordination polymer that forms the pure crystalline product. Example 3 2, / OH Me F<+AI(O-iPr}3 / OH Me 120 - 240 C •7 H2O O Me. lí P--O' / O \ .P—O MíT II O Al31 Me. DUST' / THE X, P—OH Me Π THE A resin kettle was charged with 83 g of methylphosphonic acid and heated to 120 °C. An intermediate material prepared from 50 g of methylphosphonic acid and 35.4 g of aluminum tris(isopropoxide) in the presence of water was added to the resin kettle as a syrup. The resulting solution contained a 5:1 molar ratio of methylphosphonic acid:aluminum methylphosphonic acid intermediate and was heated to 240 °C with mechanical stirring. Stirring at 240 °C continued for approximately 30 min after a solid had formed. 500 ml of H₂O were added, and the mixture was stirred for 16 h until a uniform suspension was produced. As before, the product was isolated by filtration, washed with an additional 750 ml of H2O, and dried to produce 64.3 g of the product in the form of fine colorless crystals with a yield of 93%.The empirical formula of the above product represents repeating monomeric units (i.e., coordination entities) of a coordination polymer that forms the pure crystalline product. Example 4 QpL / nn / Lznz / e / YiAi A 1 L three-necked flask was filled with 1305 g of methylphosphonic acid and heated. At 105 °C, the methylphosphonic acid melted, and vigorous stirring was initiated under vacuum. The methylphosphonic acid was heated to 180 °C, and 61 g of alumina were added as rapidly as possible without causing a large exothermic reaction or excessive foaming. The suspension was cooled to just above the melting point of the excess methylphosphonic acid, -110 °C, and then added to 1 L of H₂O while ensuring that the rate of addition did not cause excessive vapor formation. The resulting mixture was stirred to break up any large clumps that might have formed, and the product was isolated by filtration, washed with an additional 1.5 L of H2O and dried to produce 408 g of the product as fine, colorless crystals with a yield of 84%.The empirical formula of the above product represents repeating monomeric units (i.e., coordination entities) of a coordination polymer that forms the pure crystalline product. The products of each of Examples 1-4 had a P to Al ratio of 4:1 (Elemental Analysis by ICP). Example 5 A 1 L reaction vessel was charged with 1412.6 g of methylphosphonic acid, which was then heated to 165 °C under nitrogen purge (4 L / min) with stirring at 250 RPM. 78.2 g of iron oxide were added in portions without inducing a large exothermic reaction. The reaction mixture was heated at 165 °C for approximately 24 hours. The reaction mixture, containing a whitish suspension product, was then cooled to approximately 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The product was isolated by filtration, washed with an additional 500 mL of water, and dried to produce fine, whitish crystals in 83% yield. The product had a phosphorus to iron ratio of 4:1 (elemental analysis by ICP) according to the following empirical formula: QpL / nn / Lznz / e / YiAi \ .P—OH Me'U EITHER The empirical formula of the above product represents repeating monomeric units (i.e., coordination entities) of a coordination polymer that forms the pure crystalline product. Example 6 Polymeric compositions were prepared and their flame retardant activity was evaluated in UL-94 tests. UL94 V-0 ratings were measured at 0.8 mm thickness for glass-filled polymer compositions of polyamide 6,6; polyamide 6, polybutylene terephthalate (PBT); and a high-temperature polyamide containing the flame retardant produced according to Examples 1, 3, and 4 above (shown below): either P.....o .p—OH EITHER Table 1. Compositions with UL-94 V-0 classification at 0.8 mm Substrate Fiberglass RLL Inventive Melamine Melamine Cyanurate PA 6.6 30% 12.5% ​​10% - Substrate Fiberglass RLL Inventive Melamine Melamine Cyanurate PA6 25% 15% - 10% PBT 25% 15% 15% - High Temperature Nylon 25% 18% QpL / nn / Lznz / e / YiAi Additional polymer compositions containing the flame retardant produced according to Examples 1, 3, and 4 above combined with various synergistic agents in glass-filled PA 66, PBT, and 5 polyphthalamide were prepared and evaluated in UL-94 tests at a thickness of 0.8 mm. The results are provided in Table 2 (PA 66), Table 3 (PBT), and Table 4 (polyphthalamide). Samples 15, 20, and 22, which did not contain the inventive flame retardant, did not pass the UL-94 test. Table 2. PA66 Sample Formulation 5 6 7 8 9 10 11 12 13 14 15 % by weight of PA 66 47.5 46.5 46.5 46.3 45 50 40.3 45.3 45.3 46.3 70 % by weight of glass 30 30 30 30 30 30 30 30 30 30 30 % by weight of RLL Inventive 12.5 10 10 12.2 14 12 13.7 13.7 13.7 13.7 - % by weight of melon 10 10 10 10 10 - - - - - - % by weight of melon - - - - - - 16 - - - - % by weight of melon - - - - - - - 10 10 - - % by weight of melamine polyphosphate 8 Sample Formulation 5 6 7 8 9 10 11 12 13 14 15 wt% Exolit OP 1230 3.5 wt% Exolit OP 1400 3.5 wt% PPM Triazine HF 10 wt% Zinc borate - - - 1.5 - - - 1 - - - wt% Zinc stannate 1 1 UL 94 at 0.8 mm (1 / 32) V-0 V-0 V-0 V-0 V-0 V-0 V-1 V-0 V-0 V-1 Suspense Table 3. PBT QpL / nn / Lznz / e / YiAi Sample Formulation 16 17 18 19 20 wt% PBT 50 50 50 45 75 wt% glass 25 25 25 25 25 wt% RLL Inventive 15 16 15 15 - wt% melamine 10 9 9 15 - wt% polysiloxane - - 1 - - UL 94 at 0.8 mm (1 / 32) V-0 V-0 V-0 V-0 Suspense Qrunn / Lznz / e / YiAi Table 4. Polyphthalamide (high temperature polyamide) Sample Formulation 21 22 wt% polyphthalamide 57 70 wt% glass 25 30 wt% RLL Inventive 18 - UL 94 at 0.8 mm (1 / 32) V-0 Suspense Example 7 Polymeric compositions containing the flame retardant produced according to Example 5 above in PA 66 were prepared and evaluated for their flame retardant activity in UL-94 tests at a thickness of 0.8 mm. The results are provided in Table 5. Sample 24, which did not contain the inventive flame retardant, failed the UL-94 test. Table 5. PA 66 Sample Formulation 23 24 wt% PA 66 45 70 wt% glass 30 30 wt% RLL Inventive 15 - wt% melamine 10 - UL 94 at 0.8 mm (1 / 32) (0.8 mm) V-0 Suspense QpL / nn / Lznz / e / YiAi Although particular embodiments of the present invention have been illustrated and described, it will be evident to those skilled in the art, from consideration of the descriptive specification and the application of this disclosure, that various modifications and variations can be made without departing from the scope of the invention as claimed. Therefore, the specification and examples are intended to be considered illustrative only, the true scope of the present invention being indicated by the following claims and their equivalents.

Claims

1. A process for producing a phosphorus-containing flame retardant, comprising reacting at a reaction temperature a mixture comprising a suitable metal or metal compound and a stoichiometric excess with respect to the suitable metal or metal compound of an unsubstituted or alkyl or aryl-substituted phosphonic acid, wherein: - the metal is capable of forming a polycation or the suitable metal compound is represented by the formula MP(+)yXq where M is a metal, (+)y represents the charge of the metal cation, and is 2 or more, X is an anion, and the values ​​of pyq provide a balanced-charge metal compound; - the molar ratio of the unsubstituted or alkyl or aryl-substituted phosphonic acid with respect to the suitable metal or metal compound in the mixture is greater than 4:1; - the reaction temperature is 105 °C or higher; and - the unsubstituted or alkyl or aryl-substituted phosphonic acid is in a molten state at the reaction temperature.

2. A process for producing a phosphorus-containing flame retardant, comprising reacting at a reaction temperature a mixture comprising a suitable metal or metal compound and a stoichiometric excess with respect to the suitable metal or metal compound of an unsubstituted or alkyl or aryl-substituted pyrophosphonic acid, wherein: - the metal is capable of forming a polycation or the suitable metal compound is represented by the formula MP(+)yxq where M is a metal, (+)y represents the charge of the metal cation, and is 2 or more, X is an anion, and the values ​​of pyq provide a balanced-charge metal compound; - the molar ratio of the unsubstituted or alkyl or aryl-substituted pyrophosphonic acid with respect to the suitable metal or metal compound in the mixture is greater than 2:1; and - the unsubstituted or alkyl or aryl-substituted pyrophosphonic acid is in a molten state at the reaction temperature.

3. The process according to claim 1, wherein the reaction temperature is approximately 150 °C or more.

4. The process according to claim 1, wherein the reaction temperature varies from approximately 140 °C to approximately 260 °C.

5. The process according to claim 2, wherein the reaction temperature is approximately 40 °C or more.

6. The process according to claim 2, wherein the reaction temperature varies from approximately 60 °C to approximately 260 °C.

7. The process according to any one of claims 1, 3 and 4, wherein the molar ratio is 8:1 or more.

8. The process according to claim 7, wherein the molar ratio varies from approximately 10:1 to approximately 50:

1.

9. The process according to any one of claims 2, 5 and 6, wherein the molar ratio is 4:1 or more.

10. The process according to claim 9, wherein the molar ratio varies from approximately 5:1 to approximately 25:

1.

11. The process according to claim 1 or 2, wherein the mixture comprises a metal capable of forming a 2+, 3+ or 4+ polycation.

12. The process according to claim 1 or 2, wherein the mixture comprises a suitable metallic compound represented by the formula Mpi+Vxq where M is a metal, (+)y represents the charge of the metallic cation, and is 2, 3 or 4, X is an anion, and the values ​​of pyq provide a balanced charge metallic compound arunn / Lznz / e / YiAi 44.

13. The process according to claim 12, wherein y is 3.

14. The process according to claim 13, wherein M is selected from Al, Ga, Sb, Fe, Co, B and B1.

15. The process according to claim 14, wherein M is Al or Fe.

16. The process according to claim 1 or 2, wherein the reaction mixture comprises the suitable metal compound, and the suitable metal compound is selected from a metal oxide, halide, alkoxide, hydroxide, carbonate, carboxylate or phosphonate.

17. The process according to claim 16, wherein M in the formula MpWyXq is Al.

18. The process according to claim 17, wherein the suitable metal compound is selected from alumina, aluminum trichloride, aluminum trihydroxide, aluminum isopropoxide, aluminum carbonate, aluminum acetate, iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, and iron(III) acetate.

19. The process according to claim 1, wherein the unsubstituted or alkyl or aryl substituted phosphonic acid is represented by formula (I) or QpL / nn / Lznz / e / YiAi, wherein R is H, C1-12 alkyl, Cs-io aryl, C7-18 alkylaryl or C7-18 arylalkyl, wherein the alkyl, aryl, alkylaryl or arylalkyl is unsubstituted or is substituted with halogen, hydroxyl, amino, C1-4 alkylamino, C1-4 dialkylamino, C1-4 alkoxy, carboxy or C2-5 alkoxycarbonyl.

20. The process according to claim 2, wherein the unsubstituted or alkyl or aryl substituted pyrophosphonic acid is represented by the formula (a) QpL / nn / Lznz / e / YiAi or R.JI ^-p--OH / O \ --OH R II or (a). wherein R is H, C1-12 alkyl, Ce-io aryl, C7-18 alkylaryl or C7-18 arylalkyl, wherein the alkyl, aryl, alkylaryl or arylalkyl is unsubstituted or is substituted with halogen, hydroxyl, amino, C1-4 alkylamino, C1-4 dialkylamino, C1-4 alkoxy, carboxy or C2-5 alkoxycarbonyl.

21. The process according to claim 19 or 20, wherein R is an unsubstituted C1-12 alkyl, Ce aryl, C7-10 alkylaryl or C7-10 arylalkyl.

22. The process according to claim 21, wherein R is an unsubstituted C16 alkyl.

23. The process according to claim 19 or 20, wherein R is methyl, ethyl, propyl, isopropyl, butyl or t-butyl.

24. A phosphorus-containing flame retardant produced according to the process of any one of claims 1 to 23, wherein the phosphorus-containing flame retardant comprises a compound of empirical formula (III) wherein R is H, an alkyl, aryl, alkylaryl, or arylalkyl group; M is a metal and ey is 2 or 3, such that MWy is a metal cation where (+)y represents the charge formally assigned to the cation; a, b, and c represent the ratio of the corresponding components to each other in the compound and satisfy the charge balance equation 2(a)+c=b(y); and c is not zero.

25. The phosphorus-containing flame retardant according to claim 24, wherein y is 3, a is 1, b is 1, and c is 1.

26. A flame retardant polymer composition comprising (i) a polymer and (ii) the phosphorus-containing flame retardant according to claim 24 or 25.

27. The flame retardant polymer composition according to claim 26, wherein the polymer comprises one or more of a homopolymer or copolymer of polyolefin, rubber, polyester, epoxy resin, polyurethane, polysulfone, polyimide, polyphenylene ether, styrenic polymer or copolymer, polycarbonate, acrylic polymer, polyamide, or polyacetal.

28. The flame retardant polymer composition according to claim 27, wherein the polymer comprises one or more of a styrenic polymer or copolymer, polyolefin homopolymer or copolymer, polyester, polycarbonate, acrylic polymer, epoxy resin, polyamide or polyurethane.

29. The flame retardant polymer composition according to claim 28, wherein the polymer comprises a polyalkylene terephthalate, high impact polystyrene (HIPS), epoxy resin or polyamide.

30. The flame retardant polymer composition according to claim 29, wherein the polymer comprises a glass-filled polyalkylene terephthalate, glass-reinforced epoxy resin, or a glass-filled polyamide.

31. The flame-retardant polymer composition according to claim 29, wherein the polymer comprises a polyphthalamide. Qrunn / Lznz / e / YiAi 32. The flame retardant polymer composition according to claim 29, wherein the polymer comprises polyamide 46, polyamide 6, polyamide 66, polyamide 4T or polyamide 9T.

33. The flame retardant polymer composition according to claim 29, wherein the polymer comprises polyamide MXD,6, polyamide 12,T, polyamide 10,T, polyamide 6,176,6, polyamide 6,T / D,T, polyamide 6,6 / 6,T / 6,l, polyamide 6 / 6,T or polyamide 6,176,1.

34. The flame retardant polymer composition according to claim 26, wherein the polymer comprises a mixture of polyphenylene ether / styrene resin, acrylonitrile butadiene styrene (ABS), polyvinyl chloride / ABS mixture, methacrylonitrile / ABS mixture, α-methylstyrene containing ABS, polyester / ABS, polycarbonate / ABS, impact-modified polyester, or impact-modified polystyrene.

35. The flame retardant polymer composition according to any one of claims 26 to 34, further comprising (iii) one or more compounds selected from additional flame retardants, synergistic agents and flame retardant adjuvants.

36. The flame retardant polymer composition according to claim 35, wherein the one or more compounds are selected from halogenated flame retardants, alkyl or aryl phosphine oxides, alkyl or aryl polyphosphine oxides, alkyl or aryl phosphates, alkyl or aryl phosphonates, alkyl or aryl phosphinates, salts of alkyl or aryl phosphinic acid, carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes, polyphenylene ether, melamine, melamine derivatives, melamine condensation products, melamine salts, metal hydroxides, metal oxides, metal oxide hydrates, metal borates, metal carbonates, metal sulfates, metal phosphates, metal phosphonates, metal phosphites, metal hypophosphites, metal silicates, and mixed metal salts.

37. The flame-retardant polymer composition according to claim 36, wherein the one or more compounds are selected from aluminum tris(dialkylphosphinate), aluminum hydrogen phosphite, benzyl phosphine oxides, polybenzyl phosphine oxides, melam, melem, melon, melamine phosphates, melamine metal phosphates, melamine cyanurate, melamine borate, talc, clays, calcium silicate, aluminosilicate, aluminosilicate in the form of hollow tubes, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, boron phosphate, calcium molybdate, exfoliated vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate, zinc phosphate, magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum oxide hydroxide, aluminum trihydrate, silica, tin oxide, antimony (III and V) oxide, antimony (III and V) oxide hydrate, titanium oxide, zinc oxide,zinc oxide hydrate, zirconium oxide and zirconium hydroxide.

38. The flame retardant polymer composition according to claim 37, wherein one or more of the compounds are selected from aluminum tris(dimethylphosphinate), aluminum tris(diethylphosphinate), aluminum tris(dipropylphosphate), aluminum tris(dibutylphosphinate), polyaryl ether substituted with methylene-diphenylphosphine oxide, xylenebis(diphenylphosphine oxide), 1,2-bis-(9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide)ethane, 4,4'-bis(diphenylphosphinylmethyl)-1,1'-biphenyl, melam, melem, melon, and dimelamine zinc pyrophosphate.

39. The flame retardant polymer composition according to claim 26, further comprising one or more compounds selected from hydrotalcite clays, metal borates, metal oxides and metal hydroxides.

40. The flame retardant polymer composition according to claim 39, wherein the metal of the metal borates, metal oxides and metal hydroxides is zinc or calcium.

41. The flame retardant polymer composition according to claim 35, wherein one or more compounds are selected from melam, melem, melon, melamine cyanurate, melamine polyphosphate, melamine poly(metal phosphate), poly-[2,4-(piperazin-1,4-11)-6-(morpholin-4-11)-1,3,5-tzazine] / piperazine, aluminum hypophosphite, and aluminum dialkylphosphinate.

42. The flame retardant polymer composition according to claim 35, wherein one or more compounds are selected from zinc borate, zinc stannate, polysiloxanes, kaolin, silica, magnesium hydroxide, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium / zinc molybdate complex, zinc phosphate complex, and poly(zinc phosphate) melamine.

43. The flame retardant polymer composition according to claim 35, wherein the one or more compounds comprise melam and one or more materials selected from zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium / zinc molybdate complex, zinc phosphate complex, and zinc oxide.

44. The flame retardant polymer composition according to claim 35, wherein the one or more compounds comprise melon and one or more materials selected from zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium / zinc molybdate complex, zinc phosphate complex, and zinc oxide.

45. A flame retardant material comprising a compound of empirical formula (llia) QpL / nn / Lznz / e / YiAi wherein R is H, an alkyl, aryl, alkyladyl or arylalkyl group.

46. ​​The flame retardant material according to claim 45, wherein R is H or alkyl.

47. The flame retardant material according to claim 45, wherein R is C1-6 alkyl.

48. The flame retardant material according to claim 45, wherein R is methyl or ethyl.

49. The flame retardant material according to claim 45, wherein R is methyl.

50. The flame retardant material according to any one of claims 45 to 49, wherein the compound of empirical formula (llia) constitutes at least 75% by weight of the flame retardant material.

51. The flame retardant material according to claim 50, wherein the compound of empirical formula (llia) constitutes at least 90% by weight of the flame retardant material.

52. A flame retardant polymer composition comprising (i) a polymer and (ii) the flame retardant material according to any one of claims 45 to 51.

53. A process for increasing the flame resistance of a polymer, comprising incorporating the flame retardant material according to any one of claims 45 to 51 into a polymer resin, optionally with one or more additional flame retardants, synergistic agents or flame retardant adjuvants.

54. A process for increasing the flame resistance of a polymer, comprising incorporating the phosphorus-containing flame retardant according to claim 24 or 25 into a polymer resin, optionally with one or more additional flame retardants, synergistic agents, or flame retardant adjuvants.