Process for the preparation of phosphorus-containing flame retardants and their use in polymer compositions

Abstract

A phosphorus-containing flame retardant is produced by preparing a reaction mixture comprising a phosphonic acid, a solvent for the phosphonic acid, and a metal or suitable metal compound, and reacting the phosphonic acid and the metal or suitable metal compound under conditions described herein. The chemical composition of the resulting flame retardant product results in excellent flame retardancy and shows high thermal stability. The flame retardants of the present disclosure are useful in a wide range of applications, for example in polymeric compositions, particularly in thermoplastics that are processed at high temperatures.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 923,444, filed October 18, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] A highly efficient, thermally stable phosphorus-containing flame retardant is produced by a method comprising preparing a reaction mixture containing phosphonic acid or pyrophosphonic acid, a solvent for the phosphonic acid or pyrophosphonic acid, and a metal or suitable metal compound, and reacting the phosphonic acid or pyrophosphonic acid with the metal or suitable metal compound under the conditions described herein. In some embodiments, the chemical composition of the resulting flame-retardant product, produced as a compound or primarily as a compound, results in excellent flame retardancy and exhibits high thermal stability. The flame retardant disclosed herein is useful in a wide range of applications, for example in polymer compositions, particularly in thermoplastics treated at high temperatures. Background Technology

[0004] Phosphonates, namely compounds represented by the following formula, are known flame retardants in a variety of polymer compositions:

[0005]

[0006] Where R is an optionally substituted alkyl, aryl, alkylaryl, or arylalkyl group, p is typically a value from 1 to 4, M is a metal, and y is typically a value from 1 to 4, thus M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation.

[0007] As disclosed in US 2007 / 0029532, it is known that phosphonates decompose at temperatures encountered during the processing of polyesters and polyamides, such as above 260 or 270°C, resulting in the destruction of the polymer in the process.

[0008] U.S. Patent 5,053,148 discloses that brittle, heat-resistant foams can be obtained by heating phosphonates at elevated temperatures.

[0009] In Comparative Examples 1 and 2 of U.S. Patent 9,745,449, glass-filled polyamide compositions containing 10 to 25 wt% aluminum methylphosphonate salt were treated at elevated temperatures. Consistent with polymer degradation, a decrease in torque was observed during mixing, resulting in a final product material that was brittle upon cooling, dusty after grinding, and unmoldable. Further evidence of degradation was provided by analysis of the mixed material by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The observed loss of desired polymer properties is consistent with polymer degradation described in US 2007 / 0029532 and the brittle foam formed in U.S. Patent 5,053,148.

[0010] Therefore, simple phosphonates are unsuitable for use in many polymers that are processed at high temperatures such as 250°C, 260°C, 270°C or higher, or subsequently exposed to said high temperatures, because they undergo chemical transformations at these temperatures via processes that damage the polymer. This can occur, for example, during compounding in an extruder, or when the salt is present in the polymer for high-temperature applications.

[0011] On the other hand, U.S. Patent 9,745,449 discloses a method of salt-thermally converting phosphonates into distinct, more thermally stable materials that exhibit excellent flame-retardant activity when incorporated into a polymer matrix (substrate), typically by heating phosphonates at sufficiently high temperatures in the absence of other materials. When treated in polymer compositions at elevated temperatures such as 240°C, 250°C, 260°C, 270°C, or higher, the thermally converted materials do not degrade at these temperatures, nor do they cause polymer degradation. This is a significant advantage compared to previously known phosphonates that exhibit flame-retardant activity but typically degrade the polymer during treatment. Thermally converted materials are described as comprising one or more compounds represented by empirical formula (IV):

[0012]

[0013] Where R is an alkyl or aryl group, 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 1 to 4, and n is 1 or 2, with the condition 2(q) + r = n(y).

[0014] However, the methods and materials of U.S. Patent 9,745,449 face challenges, such as the fact that the product is typically produced in the form of a solid mass that requires grinding, milling, or other physical treatment 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. Additionally, examples in U.S. Patent 9,745,449 describe the production of phosphorus-containing flame retardants in several steps, wherein an intermediate metal salt of phosphonic acid is produced and then the salt is heated and dried at a temperature above 200°C.

[0015] This disclosure addresses the aforementioned challenges while also producing phosphorus-containing flame retardants without the need to generate or use intermediate salts as described in U.S. Patent 9,745,449. Summary of the Invention

[0016] According to the present invention, a phosphorus-containing flame retardant is prepared by the following method, the method comprising: (i) preparing a reaction mixture comprising (a) an unsubstituted or alkyl- or aryl-substituted phosphonic acid, (b) a solvent for the phosphonic acid, and (c) a metal capable of forming a polycation (i.e., in its corresponding cationic form by formula M). (+)y The metal represented by M, where M is a metal, (+)y represents the charge of the metal cation, and y is 2 or higher, or by formula M p (+)y X q The suitable metal compound represented by M is a metal, (+)y represents the charge of the metal cation, y is 2 or higher, X is an anion, and the values ​​of p and q provide a charge-balanced metal compound; and (ii) the amount of time that the reaction mixture is heated at a reaction temperature of 105°C or higher or reacted sufficiently to produce a phosphorus-containing flame retardant.

[0017] A method for producing phosphorus-containing flame retardants is also disclosed, the method comprising (i) preparing a reaction mixture comprising (a) an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid, (b) a solvent for the pyrophosphonic acid, and (c) a metal capable of forming polycations (i.e., in its corresponding cationic form by M as shown above). (+)y (representing the metal), or by formula M above p (+)y X q (ii) the appropriate metal compound, and (iii) the reaction mixture is heated at a reaction temperature of 20°C or higher for a time sufficient to produce a phosphorus-containing flame retardant.

[0018] Typically, as the flame-retardant product obtained by this invention precipitates from the reaction mixture, the reaction product forms a slurry. Residual phosphonic acid, pyrophosphonic acid, and / or solvents after the reaction can be removed by filtration and / or washing with water, along with any possible byproducts. In some embodiments, substantially pure flame-retardant materials are produced, such as flame retardants comprising a substantially single compound or a mixture of substantially active compounds. The conversion based on metals or metal compounds is generally high, and the product can be readily separated and optionally further purified if desired.

[0019] The method of the present invention overcomes the difficulties observed in methods such as those in U.S. Patent 9,745,449, for example, by reducing or avoiding the generation of water-soluble or thermally unstable compounds, and by directly producing flame-retardant products, typically crystalline as powders or small particles, in an easily processable form, i.e., without or without the need for grinding, granulation, or other such physical processing. Furthermore, in some embodiments, the resulting flame-retardant material according to this disclosure has a higher phosphorus-to-metal ratio than observed for simple metal phosphonates, as further explained herein. The high phosphorus-to-metal ratio in the resulting flame retardant results in greater efficacy and therefore allows for lower loading levels when the flame-retardant material is mixed with thermoplastics.

[0020] Other embodiments of this disclosure include, but are not limited to, phosphorus-containing flame retardants produced according to the methods described herein; flame retardant polymer compositions comprising (i) a polymer and (ii) the phosphorus-containing flame retardant of this disclosure; methods for improving the flame retardancy of a polymer by incorporating the flame retardant of this disclosure therein; and methods for incorporating a flame retardant composition comprising the flame retardant of this disclosure into a polymer.

[0021] The above description of the invention is not intended to limit the scope of the claimed invention in any way. Furthermore, it should be understood that both the above general description and the following detailed description are exemplary and illustrative only, and are not intended to limit the invention as claimed. Attached Figure Description

[0022] Figure 1 Thermogravimetric analysis (TGA) results of an exemplary flame retardant material produced according to Embodiment 1 of this disclosure are shown. Detailed Implementation

[0023] Unless otherwise stated, in this application, the word "a" or "a kind" means "one or more".

[0024] Unless the context otherwise requires, the term "alkyl" in this application includes "arylalkyl".

[0025] Unless the context otherwise requires, the term "aryl" in this application includes "alkylaryl".

[0026] Unless the context otherwise requires, the term "phosphonic acid" as used herein refers to unsubstituted or alkyl- or aryl-substituted phosphonic acids.

[0027] Unless the context otherwise requires, the term "pyrophosphonic acid" as used herein refers to unsubstituted or alkyl- or aryl-substituted pyrophosphonic acids.

[0028] According to one aspect of this disclosure, a metal or suitable metal compound reacts with an unsubstituted or alkyl- or aryl-substituted phosphonic acid to form a phosphorus-containing flame retardant. The method comprises (i) preparing a reaction mixture comprising (a) an unsubstituted or alkyl- or aryl-substituted phosphonic acid, (b) a solvent for the phosphonic acid, and (c) a metal or suitable metal compound; and (ii) heating the reaction mixture at a reaction temperature of 105°C or higher or reacting for a time sufficient to produce the phosphorus-containing flame retardant. In the reaction, the metal is oxidized and can be reacted in its corresponding cation form by formula M (+)y This indicates that M is a metal, (+)y represents the charge of the metal cation, and y is 2 or higher. It can be derived from equation M. p (+)y X q The denot represents a suitable metal compound, where M is a metal, (+)y represents the charge of the metal cation, y is 2 or higher, X is an anion, and the values ​​of p and q provide the charge-balanced metal compound.

[0029] In another aspect, a metal or suitable metal compound is reacted with an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid to form a phosphorus-containing flame retardant. The method comprises (i) preparing a reaction mixture containing (a) an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid, (b) a solvent for the pyrophosphonic acid, and (c) the metal or suitable metal compound as described above; and (ii) heating the reaction mixture at a reaction temperature of 20°C or higher or reacting for a time sufficient to produce the phosphorus-containing flame retardant.

[0030] In some embodiments, the molar ratio of phosphonic acid or pyrophosphonic acid to a metal or suitable metal compound in the reaction mixture is greater than 2:1, such as about 3:1 or higher, about 4:1 or higher, about 5:1 or higher, about 6:1 or higher, about 7:1 or higher, or about 8:1 or higher. Typically, a larger molar excess of phosphonic acid or pyrophosphonic acid relative to a metal or suitable metal compound is used in the reaction mixture, such as about 10:1 or higher, about 15:1 or higher, about 20:1 or higher, about 25:1 or higher, about 30:1 or higher, or any range therein. Large molar excesses of phosphonic acid or pyrophosphonic acid relative to a metal or suitable metal compound can be used. For example, molar ratios can be as high as about 50:1, up to about 100:1, up to about 300:1, up to about 500:1, or any range therein. However, as will be understood, at certain large molar excesses, processing efficiency may deteriorate, for example, it may prevent the precipitation of products from the reaction mixture. In some implementations, the molar ratio ranges from about 4:1, from about 5:1, from about 6:1, from about 8:1 or from about 10:1 to about 100:1 or to about 50:1, such as from about 8:1, from about 12:1, from about 16:1 or from about 20:1 to about 50:1 or to about 40:1.

[0031] According to the method disclosed herein, the reaction mixture is heated at the reaction temperature as described herein for a sufficient amount of time to produce a flame-retardant product. As used herein, the step of “heating the reaction mixture at the reaction temperature for a sufficient amount of time to produce a phosphorus-containing flame retardant” includes, but is not limited to, embodiments in which all or substantially all of component (b) of the reaction mixture—i.e., the solvent of phosphonic acid or pyrophosphonic acid—is evaporated from the reaction mixture during the process of heating the reaction mixture to the reaction temperature or during the process of heating at the reaction temperature. Therefore, it should be understood that the term “reaction mixture” as described herein is still referred to as heating at the reaction temperature, even if all or substantially all of the solvent component (b) is evaporated during the process of heating the reaction mixture to the reaction temperature or during the process of heating at the reaction temperature.

[0032] According to this disclosure, the reaction temperature for generating the phosphorus-containing flame retardant should be selected to promote the formation of monoanionic and / or dianionic pyrophosphonic acid ligands in the reaction products. For phosphonic acids, a reaction temperature of 105°C or higher is used. Without being bound by specific theory, the reaction temperature is selected to generate the pyrophosphonic acid ligands via a dehydration reaction. In some embodiments, the metal or suitable metal compound and the phosphonic acid are reacted at temperatures above 105°C, such as about 115°C or higher, about 120°C or higher, about 130°C or higher, about 140°C or higher, about 150°C or higher, about 160°C or higher, about 170°C or higher, about 180°C or higher, about 200°C or higher, about 220°C or higher, about 240°C or higher, about 260°C or higher, about 280°C or higher, or any range therebetween. The reaction temperature can be higher than those mentioned above, such as up to about 350°C, up to about 400°C or higher, but it generally does not reach or exceed the boiling point temperature of the phosphonic acid. In some embodiments, the reaction temperature ranges from about 110°C to about 350°C, about 115°C to about 300°C, about 125°C to about 280°C, or about 140°C to about 260°C. Water is formed through a dehydration reaction, which can potentially lead to an undesirable reverse (hydrolysis) reaction. Therefore, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction mixture, such as continuous removal. For example, the reaction temperature can be selected above the boiling point of water until at least some or the desired amount (e.g., most, substantially all, or all) of the water is evaporated from the reaction. Other methods such as gas purging, vacuum, and / or other known methods can be used to facilitate the removal of water from the reaction system.

[0033] For pyrophosphonic acid, a reaction temperature of 20°C or higher is used. Since dehydration is not necessary for pyrophosphonic acid, the reaction temperature can be lower than the temperatures described above for phosphonic acid. In some embodiments, the metal or suitable metal compound and pyrophosphonic acid react at temperatures above 20°C, such as about 40°C or higher, about 60°C or higher, about 80°C or higher, about 100°C or higher, about 140°C or higher, about 180°C or higher, about 200°C or higher, or any range therebetween. The reaction temperature can be higher than those mentioned above, such as up to about 300°C, up to about 400°C or higher, but it generally does not reach or exceed the boiling point temperature of pyrophosphonic acid. In some embodiments, the reaction temperature ranges from about 25°C to about 350°C, about 25°C to about 280°C, about 30°C to about 260°C, about 40°C to about 260°C, or about 60°C to about 240°C. For example, water can be produced from the reaction based on the metal compound used to react with pyrophosphonic acid. As described above, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction, such as continuous removal. For example, the reaction temperature can be selected above the boiling point of water until at least some or the desired amount (e.g., most, substantially all, or all) of the water is evaporated from the reaction. Other methods, such as gas purging, vacuum, and / or other known methods, can be used to facilitate the removal of water from the reaction system.

[0034] In some embodiments, the solvent is a protic solvent (e.g., water) and the reaction system is designed to facilitate the removal, such as continuous removal, of the protic solvent during heating of the reaction mixture. For example, the reaction temperature can be selected at or above the boiling point of the protic solvent until at least some or a desired amount (e.g., most, substantially all, or all) of the protic solvent is evaporated during heating of the reaction mixture. In some embodiments, the solvent is water and the reaction temperature is about 110°C or higher, about 115°C or higher, about 120°C or higher, about 130°C or higher, about 140°C or higher, about 150°C or higher, or about 160°C or higher, as exemplified above. The reaction temperature can also be selected at or above the melting point of phosphonic acid or pyrophosphonic acid, as further described herein.

[0035] As described above, this refers to the amount of time required to heat the reaction mixture at the reaction temperature or react sufficiently to produce a phosphorus-containing flame retardant. Typically, the flame retardant product will precipitate from the reaction mixture, thus requiring sufficient time for the reaction to proceed to achieve this precipitation. Generally, the amount of time required to achieve at least a significant conversion to the flame retardant product will depend on the reaction temperature, with higher temperatures typically resulting in shorter reaction times, depending on the metal or suitable metal compound in the reaction mixture. Typically, heating or reaction occurs at the reaction temperature for about 0.1 to about 48 hours, such as about 0.2 to about 36 hours, about 0.5 to about 30 hours, about 1 hour to about 24 hours, for example about 1 hour to about 12 hours, about 1 hour to about 8 hours, or about 1 hour to about 5 hours, but other durations may be used.

[0036] The reaction mixture can be prepared in any manner suitable for combining or mixing (a) an unsubstituted or alkyl- or aryl-substituted phosphonic acid or pyrophosphonic acid, (b) a solvent for the phosphonic acid or pyrophosphonic acid, and (c) a metal or suitable metal compound. For example, the components can be combined simultaneously or at different times. In some embodiments, the metal or suitable metal compound (c) is added to a mixture of the phosphonic acid or pyrophosphonic acid (a) and the solvent (b), such as a solution. The metal or suitable metal compound (c) can be added to the reaction mixture once or in portions. Similarly, the phosphonic acid or pyrophosphonic acid (a), the solvent (b), or a mixture of the phosphonic acid or pyrophosphonic acid (a) and the solvent (b), such as a solution, can be added to the reaction mixture once or in portions.

[0037] In preparing the reaction mixture, phosphonic acid or pyrophosphonic acid (a), a solvent (b), and a metal or suitable metal compound (c) may be combined at a preparation temperature below the reaction temperature. The reaction mixture is then heated to the reaction temperature. For example, the preparation temperature may be chosen to induce the phosphonic acid or pyrophosphonic acid (a) to dissolve (dissolve) in the solvent (b) or to additionally form a homogeneous liquid or solution of the phosphonic acid or pyrophosphonic acid (a) and the solvent (b). At the preparation temperature and based on the metal compound (c), the reaction mixture may form a solution, suspension, or slurry, such as a homogeneous or substantially homogeneous suspension or slurry. In some embodiments, the reaction mixture may form a solution, such as at a higher preparation temperature. Typically, the reaction mixture will exist as a solution near or at the reaction temperature. In some embodiments, the preparation temperature is about 0°C or higher, but typically below 150°C, such as below 125°C, below 115°C, below 100°C, below 85°C, or below 65°C. For example, the preparation temperature may range from about 0°C to about 65°C or from about 15°C to about 40°C. In some embodiments, the reaction mixture is prepared at room temperature (e.g., from about 15°C to about 25°C). In some embodiments, the solvent (b) is preheated to the preparation temperature and combined with phosphonic acid or pyrophosphonic acid (a) and a metal or suitable metal compound (c). In some embodiments, the mixture of solvent (b) and phosphonic acid or pyrophosphonic acid (a) is preheated to the preparation temperature and combined with a metal or suitable metal compound (c).

[0038] Alternatively, the reaction mixture can be prepared at the reaction temperature. That is, the reaction mixture is prepared by combining (a) phosphonic acid or pyrophosphonic acid, (b) a solvent of phosphonic acid or pyrophosphonic acid, and (c) a metal or suitable metal compound at the reaction temperature. For example, in some embodiments, preparing the reaction mixture includes preheating a mixture of solvent (b) and phosphonic acid or pyrophosphonic acid (a) to the reaction temperature and combining it with a metal or suitable metal compound (c).

[0039] In some embodiments where the reaction temperature is above the melting temperature of phosphonic acid or pyrophosphonic acid and residual phosphonic acid or pyrophosphonic acid remains in the product reaction mixture after the desired conversion to the flame-retardant product, such as complete or substantially complete conversion, is achieved, the product reaction mixture is cooled to a temperature above or not below the melting temperature of the residual phosphonic acid or pyrophosphonic acid to ensure that the phosphonic acid or pyrophosphonic acid remains in liquid form. This can be particularly useful in embodiments where a large amount of the solvent of phosphonic acid or pyrophosphonic acid (i.e., component (b)) evaporates due to heating, so that the remaining excess phosphonic acid or pyrophosphonic acid may have a greater tendency to leave the solution. If present in the product reaction mixture, excess phosphonic acid or pyrophosphonic acid and solvent can be removed by filtration / washing and optionally recycling. For example, the recovered excess phosphonic acid or pyrophosphonic acid and / or solvent can be recycled to a reactor in which the metal or suitable metal compound (c) reacts with phosphonic acid or pyrophosphonic acid (a). After conversion to the reaction product, a solvent of the same phosphonic acid or pyrophosphonic acid as solvent component (b) may be added optionally to dissolve or additionally aid in the removal of excess phosphonic acid or pyrophosphonic acid. Flame retardant products are typically separated by filtration, optionally followed by further processing (e.g., washing, drying, sieving, etc.). The resulting flame retardant products, usually in powder or particulate form, are readily handleable, meaning that grinding, milling, or other such physical treatment is unnecessary or undesirable before use. It should be understood that the processing of reaction products, such as separation of flame retardant products (e.g., separation of flame retardant products from residual solvents), is permitted “directly” as a powder or particulate form of the flame retardant material, according to the method disclosed in this invention. This may include, for example, processing the reaction products by filtration, sieving, washing, drying, etc.

[0040] The methods disclosed herein yield flame retardants comprising one or more metals and one or more monodentate and / or bidentate pyrophosphonic acid ligands. In some embodiments, compounds further comprising phosphonate ligands may be produced, but in all embodiments, compounds comprising pyrophosphonic acid monoanionic ligands and / or pyrophosphonic acid dianionic ligands are obtained.

[0041] This method can yield mixtures of flame-retardant compounds, but in some embodiments, unlike mixtures of compounds obtained using prior art methods involving heat treatment of metal phosphonates, this method, based on a metal or metal compound, produces a flame-retardant material at a high conversion rate, such as at least 70%, 80%, 85%, 90%, 95%, 98%, or higher, or any range therebetween, based on a metal or metal compound. In general embodiments, where phosphonate ligands may be present in the flame-retardant product, the reaction typically proceeds as follows:

[0042]

[0043] Where M is a metal cation and (+)y represents the cation charge, for example, M is a di, tri, tetra, or pentacation metal; X is an anionic ligand or a ligand attached to a metal, and the stoichiometry of M and X (i.e., p and q) provides a charge-balanced metal compound; R is H, alkyl, aryl, alkylaryl, or arylalkyl; a, b, c, and d represent the proportions of their corresponding portions in the reaction product relative to each other, and y, a, b, c, and d are values ​​that provide a charge-balanced product, provided that y is 2 or higher and only one of a or c can be 0 (typically, c is not zero). In some embodiments, the above phosphonic acid ligands having a coefficient d can exist as divalent anions when present. In some embodiments, d is 0.

[0044] In another aspect, the flame-retardant products produced according to this disclosure (typically in powder or particulate form) comprise compounds represented by empirical formula (II) or mixtures of different compounds.

[0045]

[0046] Where R is H, alkyl, aryl, alkylaryl, or arylalkyl, a, b, c, and d represent the proportions of their corresponding portions in the compound relative to each other, and a is typically a value from 0 to 8, such as 0 to 6, 0 to 4, or 0 to 2; c is typically a value from 0 to 10, such as 0 to 8, 0 to 6, 0 to 4, or 0 to 2; d is typically a value from 0 to 6, such as 0 to 4 or 0 to 2; M is a metal; y is a value from 2 to 5, such as 2, 3, or 4, usually 2 or 3; and M... (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation. The values ​​of a, b, c, d, and y can be different, but they will satisfy the charge balance equation 2(a) + c + d = b(y), and only one of a or c can be 0. In some embodiments, c is not zero. In the case where a dianionic phosphonic acid ligand can be present in the compound, the charge balance equation becomes 2(a) + c + 2(d) = b(y). The value of b is limited to the fact that it must satisfy the above equation, but in some embodiments, b is a value from 1 to 4, for example, 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 is charge balanced.

[0047] In some implementations, d is 0, as in the following:

[0048]

[0049] R, M, y, a, b, and c are as described above, and the charge balance equation for the product becomes 2(a) + c = b(y).

[0050] Typically, c in equations (II) and (III) above is not zero (e.g., c is 1 to 10, 1 to 8, 1 to 6, 1 to 4, or 1 or 2).

[0051] According to the method disclosed in this invention, it has been unexpectedly found that in some embodiments, such as when using dicationic or tricationic metals, the resulting flame-retardant compound has a phosphorus to metal atom (i.e., P to M) ratio that is more favorable for providing flame retardancy than that of phosphorus-containing flame retardants described in the art. For example, it is known that tricationic metals (e.g., aluminum) and dicationic metals (e.g., zinc) form trisubstituted and disubstituted charge-balanced compounds, respectively. As shown in the art, aluminum triphosphonates—having a phosphorus to aluminum ratio of 3:1—and zinc diphosphonates—having a phosphorus to zinc ratio of 2:1—are known as flame retardants. However, according to this disclosure and specifically in the formation of pyrophosphonic acid ligands where c in the above formula 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 using the method of this disclosure, the resulting flame-retardant product has a phosphorus to aluminum ratio or a phosphorus to iron ratio of 4:1. This higher phosphorus-to-metal ratio results in high efficiency and allows for reduced loading when mixed into thermoplastic polymers.

[0052] In some specific implementations, y in equation (III) is 2 (i.e., M (+)y (where M is a dicationic metal, as described herein), a is 0, b is 1, and c is 2. In some embodiments, the dicationic metal M is Mg, Ca, or Zn. In other embodiments, y in formula (III) is 3 (i.e., M is 2). (+)y The tricationic metal M is a tricationic metal (as described herein), where a is 1, b is 1, and c is 1. In some embodiments, the tricationic metal M is selected from Al, Ga, Sb, Fe, Co, B, and Bi. In some embodiments, the tricationic metal M is Al, Fe, Ga, Sb, or B.

[0053] For inorganic coordination compounds, the reaction products in the above reactions and the compounds in empirical formulas (II) and (III) are idealized, so the reaction products or compounds can be coordination polymers, complex salts, salts in which certain atomic valence states are shared, etc.

[0054] For example, in some embodiments, empirical formulas (II) or (III) as described herein represent monomer units (i.e., coordination entities) of the coordination polymer, and the extended coordination polymer structure thereby forms the flame retardant compounds of this disclosure.

[0055] In one instance, where M is Al and y is 3, the compound of empirical formula (III) is produced according to the following empirical formula (IIIa):

[0056]

[0057] As illustrated herein, the absence of subscripts a, b, and c in the empirical formula indicates that the subscripts are 1, thus indicating a 1:1:1 ratio of the components (in the case of empirical formula (IIIa), the ratio of the dianionic pyrophosphonic acid ligand, the metal atom, and the monoanionic pyrophosphonic acid ligand is 1:1:1). In this example, empirical formula (IIIa) represents the repeating monomer unit (i.e., the coordination entity) of the coordination polymer, and the extended coordination polymer structure thereby forms the flame retardant compound of this disclosure.

[0058] Typically, compounds of empirical formula (II) or (III) (e.g. (IIIa)), which in some embodiments are extended coordination polymers as described herein, constitute 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 range therebetween by weight of the flame retardant product.

[0059] Compounds of empirical formula (II) or (III) (e.g., (IIIa)) can be produced based on metals or metal compounds at high conversion rates, such as at least 70%, 80%, 85%, 90%, 95%, 98%, or higher, for example at least 70 to 95% or higher. In some embodiments, M is aluminum (i.e., using aluminum or one or more aluminum compounds to produce reaction products, as described herein) or iron (i.e., using iron or one or more iron compounds to produce reaction products, as described herein).

[0060] The phosphonic acid used in this method can be represented by formula (I):

[0061]

[0062] Wherein R is H, alkyl, aryl, alkylaryl, or arylalkyl. In some embodiments, R is H or C. 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl or C 7-18 arylalkyl, wherein the alkyl, aryl, alkylaryl, or arylalkyl group is unsubstituted or converted by halogen, hydroxyl, amino, C 1-4 Alkylamino, di-C 1-4 Alkylamino, C 1-4 Alkoxy, carboxyl or C 2-5 Alkoxycarbonyl substitution. In some embodiments, the alkyl, aryl, alkylaryl, or arylalkyl group is an unsubstituted C10. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Arylalkyl, such as C1-6 Alkyl, phenyl or C 7-9 Alkyl aryl. In some embodiments, R is a substituted or unsubstituted C. 1-6 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-12 Arylalkyl, such as C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl or C 7-10 Arylalkyl. In some embodiments, R is an unsubstituted C. 1-12 Alkyl, such as C 1-6 Alkyl groups. In some embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0063] As an alkyl group, R can be a straight-chain or branched alkyl group having a specified number of carbons, and includes, for example, non-branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl, as well as branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, ethylhexyl, and tert-octyl. For example, R can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl. In some embodiments, R is methyl, ethyl, propyl, or isopropyl, such as methyl or ethyl.

[0064] Typically, when R is aryl, it is phenyl. Examples of R as an alkylaryl group include phenyl groups substituted with one or more alkyl groups, such as those selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, etc. Examples of R as arylalkyl groups include benzyl, phenethyl, styryl, cumyl, phenylpropyl, etc.

[0065] In some embodiments, R is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl.

[0066] The pyrophosphonic acid used in the method of this invention can be represented by formula (Ia):

[0067]

[0068] R is as described above for equation (I).

[0069] The general reaction scheme using pyrophosphonic acid and a suitable metal compound can be represented as follows: R, M, X, p, q, y, a, b, and c are as described in this article.

[0070] The methods disclosed herein may use more than one phosphonic acid, more than one pyrophosphonic acid, or a combination of phosphonic and pyrophosphonic acids. In some embodiments, phosphonic acids or pyrophosphonic acids are generated in situ. For example, preparing the reaction mixture may include preparing phosphonic acids or pyrophosphonic acids, such as by hydrolysis of higher oligophosphonic acids and / or cyclic phosphonic anhydride starting materials.

[0071] The solvent (i.e., component (b)) can be any solvent capable of dissolving phosphonic acid or pyrophosphonic acid component (a), and should be inert or substantially inert to the reaction between phosphonic acid or pyrophosphonic acid (a) and a metal or suitable metal compound (c). Other reaction parameters, such as preparation and / or reaction temperature, or the type of metal or suitable metal compound, can be considered to further select the solvent, thereby preparing a homogeneous or substantially homogeneous reaction mixture. In some embodiments, solvent (b) can be a combination of solvents for phosphonic acid or pyrophosphonic acid. Typically, phosphonic acid or pyrophosphonic acid (a) is substantially or completely soluble in solvent (b). For example, phosphonic acid or pyrophosphonic acid (a) and solvent (b) can form a solution. In some embodiments, phosphonic acid or pyrophosphonic acid (a) can be partially dissolved and partially suspended or dispersed in solvent (b). The type of solvent, the amount of solvent relative to phosphonic acid or pyrophosphonic acid, and mixing conditions can be selected to achieve a desired level of phosphonic acid dissolution, thereby obtaining a high concentration of phosphonic acid or pyrophosphonic acid in the mixture while maintaining the phosphonic acid or pyrophosphonic acid in solution. Typically, the ratio of phosphonic acid (a) to solvent (b) is in the range of about 10:1 to 1:10, about 5:1 to 1:5, or about 3:1 to 1:3 by weight. In some embodiments in which phosphonic acid (a) is partially dissolved and partially suspended or dispersed in solvent (b), the preparation temperature or reaction temperature may be selected at or above the melting temperature of phosphonic acid to liquefy the phosphonic acid suspended or dispersed in the solvent.

[0072] As described above, based on the reaction temperature and the boiling point of the solvent (i.e., component b in the reaction mixture) of phosphonic acid or pyrophosphonic acid, at least a portion of the solvent can be evaporated from the reaction mixture while heating to the reaction temperature or heating at the reaction temperature. In some embodiments, all, substantially all, or at least most of the solvent (b) is evaporated from the reaction mixture during heating. The solvent (b) can be a high-boiling-point solvent (e.g., sulfolane or dimethyl sulfoxide (DMSO)) or a low-boiling-point solvent (e.g., chloroform or tetrahydrofuran (THF)). For example, in some embodiments, the solvent boils at or below the reaction temperature, thereby evaporating at least a portion of the solvent during heating of the reaction mixture, such as all, substantially all, or most of the solvent being evaporated. The reaction temperature can be selected at or above the melting point of the phosphonic acid or pyrophosphonic acid to ensure that they remain in liquid form while the solvent is evaporated. In this way, a large excess of phosphonic acid or pyrophosphonic acid used in the reaction mixture allows the phosphonic acid or pyrophosphonic acid to be used as both a reactant and a solvent in the reaction.

[0073] In other embodiments, the solvent has a boiling point temperature higher than the reaction temperature, thereby ensuring that it remains in the product reaction mixture, from which the flame-retardant product of the reaction can be separated, as described herein. In some embodiments, a reaction temperature lower than the melting temperature of phosphonic acid or pyrophosphonic acid is selected.

[0074] Suitable solvents can be organic or inorganic. Examples of suitable solvents for phosphonic or pyrophosphonic acids include, but are not limited to, water, sulfones, sulfoxides, halogenated (e.g., chlorinated) hydrocarbons, aromatic hydrocarbons, and ethers. For example, in some embodiments, the solvent may be selected from water, sulfolane, dimethyl sulfone, tetrahydrofuran (THF), dimethoxyethane (DME), 1,4-dioxane, dimethyl sulfoxide (DMSO), 1,2-dichlorobenzene, chloroform, carbon tetrachloride, xylene, and mesitylene. In some embodiments, the solvent includes water. In some embodiments, the solvent includes an aqueous solution. In some embodiments, the reaction mixture is an aqueous reaction mixture.

[0075] The solvent can be proton or aproton. In some embodiments, the solvent for pyrophosphonic acid is an aprotic solvent.

[0076] In some embodiments, solvent (b) comprises a sulfone of formula R1R2SO2, wherein R1 and R2 are independently selected from C 1-6 Hydrocarbon groups, such as C 1-3 A hydrocarbon group, or R1 and R2 combined with S to form a ring with 2, 3, 4, or 5 carbon atoms, the ring can be unsubstituted or C. 1-3 Alkyl-substituted. In some embodiments, R1 and R2 together with S form a di-, tri-, tetra-, or penta-methylene ring. In some embodiments, R1 and R2 are independently selected from C.1-6 Alkyl group. In some embodiments, R1 or R2 is C12. 1-6 Alkyl and another is C 1-3 Alkyl group. In some embodiments, R1 and R2 are independently selected from C1 and C2. 1-3 Alkyl group. The alkyl group can be branched or straight-chain. In some embodiments, R1 and R2 are both methyl, both ethyl, or both propyl. In other embodiments, R1 or R2 is methyl and the other is ethyl or propyl. In other embodiments, R1 or R2 is ethyl and the other is propyl. In some embodiments, the sulfone is sulfolane.

[0077] As used in this article, the expression M such as "suitable metal compound" p (+)y X q The compounds shown are in which M is a metal capable of forming polycations, such as metals forming 2+, 3+, 4+, or 5+, typically 2+, 3+, or 4+ cations, and X is any anion that provides a compound that is charge-balanced with metal M. Suitable examples of X include, but are not limited to, anions that form oxides, halides, alcohols, hydroxides, carbonates, carboxylates, and phosphonates with metal M. The values ​​of p and q provide charge-balanced metal compounds, such as aluminum oxide, Al2O3. In some embodiments, an unsubstituted metal M as described herein is used. Suitable examples of metals (M) include, but are not limited to, Mg, Ca, Ba, Zn, Zr, Ge, B, Al, Si, Ti, Cu, Fe, Co, Ga, Bi, Mn, Sn, or Sb. In some embodiments, M is selected from Mg, Ca, Ba, Zn, Zr, Ga, B, Al, Si, Ti, Cu, Fe, Sn, or Sb. In some embodiments, M is selected 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.

[0078] Suitable metal compounds include, but are not limited to, compounds having metal-oxygen bonds, metal-nitrogen bonds, metal-halogen bonds, metal-hydrogen bonds, metal-phosphorus bonds, metal-sulfur bonds, and metal-boron bonds, such as oxides, halides, alcohols, hydroxides, carboxylates, carbonates, phosphonates, phosphinates, and phosphonites of Mg, Ca, Ba, Zn, Zr, Ge, B, Al, Si, Ti, Cu, Fe, Co, Ga, Bi, Mn, Sn, or Sb. Phosphates, phosphites, nitrates, nitrites, borates, hydrides, sulfonates, sulfates, thioethers, etc., such as oxides, hydroxides, halides, or alcohols of Mg, Ca, Ba, Zn, Zr, Ga, B, Al, Si, Ti, Cu, Fe, Sn, or Sb; such as oxides, hydroxides, halides, or alcohols of Mg, Ca, Ba, Zn, Zr, B, Al, Si, Ti, Fe, Sn, or Sb.

[0079] In some embodiments, the metal M, or suitable metal compound, is aluminum or iron. In some embodiments, suitable metal compounds are selected from aluminum halides, oxides, hydroxides, alcohols, carbonates, carboxylates, and phosphonates. In some embodiments, suitable metal compounds are selected from aluminum halides, oxides, hydroxides, and alcohols. In some embodiments, suitable metal compounds are selected from alumina, aluminum trichloride, aluminum hydroxide, isopropyl alumina, aluminum carbonate, and aluminum acetate. In other embodiments, suitable metal compounds are selected from iron halides, oxides, alcohols, carbonates, and acetates. In some embodiments, suitable metal compounds are selected from iron(III) oxide, iron(III) chloride, isopropyl iron(III) oxide, and iron(III) acetate.

[0080] In some embodiments, a suitable metal compound is a metal phosphonate. The metal in the metal phosphonate may be metal M as described herein. In some embodiments, the metal phosphonate is prepared from the reaction of an initial metal compound and a phosphonic acid with a solvent (e.g., water) for the phosphonic acid. The initial metal compound may be a compound of a suitable metal compound as described herein. In some embodiments, the initial metal compound and the phosphonic acid are reacted at room temperature or near room temperature or at a temperature in the range of about 0 to about 20°C. The resulting metal phosphonate can then be used as a suitable metal compound according to the method of the invention described herein. For example, the phosphonic acid, such as one or more alkylphosphonic acids as described above, and a solvent (e.g., water) can be stirred to form a homogeneous solution. The solution can be cooled, for example, from about 0 to about 20°C, and an initial metal compound, such as a metal oxide, halide, alcohol, or hydroxide, can be added to react with the phosphonic acid. A metal phosphonate is formed, and then the metal phosphonate is used as a suitable metal compound according to the method disclosed herein.

[0081] In some embodiments, as shown herein, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al, Fe, Zn, or Ca. In other embodiments, X is oxygen, hydroxyl, alkoxy, or halogen.

[0082] The reactions described in this article can, but do not need to, be carried out under reduced pressure or vacuum.

[0083] The product reaction mixture (typically present as a slurry) formed by the reaction described herein may be combined with other solvents, which may be the same as or different from the solvent used in the reaction mixture. For example, the other solvents may be selected from those described herein with respect to solvent component (b). The other solvent / slurry mixture may be stirred as needed to break up any agglomerates that may have formed. The solid product may be separated by filtration, optionally washing, and drying to obtain a product in powder or fine particle form. In some cases, the product may be sieved to refine the particle size.

[0084] The reaction as described herein can be optionally facilitated by seed material. For example, the use of seed material can reduce the time to conversion to the flame-retardant product and can result in improved consistency of the product's physical characteristics. Therefore, in some embodiments, the reaction mixture further includes seed material (d). Typically, the seed material is added to the reaction mixture while or after heating to the reaction temperature. In some embodiments, the seed material is added before conversion to the flame-retardant product and / or precipitation of the flame-retardant product occurs. In some embodiments, the seed material comprises a flame-retardant material produced according to the method of this disclosure, such as a flame-retardant compound represented by empirical formulas (II), (III), or (IIIa) as described herein. The seed material can be selected or refined to have a desired particle size.

[0085] In some embodiments, a suitable metal compound is aluminum oxide, and the flame-retardant material is produced as follows:

[0086]

[0087] In one instance, it will contain phosphonic acids such as C1-C 12 The reaction mixture of alkyl phosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid), a solvent for the phosphonic acid such as water, and an oxide, hydroxide, halide, alcohol, carbonate, or carboxylate of Al (e.g., alumina, aluminum trichloride, aluminum hydroxide, isopropyl alumina, aluminum carbonate, or aluminum acetate) is heated to a reaction temperature as described herein, such as about 115°C or higher, about 125°C or higher, about 150°C or higher, or about 165°C or higher. Typically, a slurry forms as the reaction proceeds, and the solid flame retardant product can be separated by filtration to obtain a product in powder or particulate form. Further finishing of the product reaction mixture may be performed prior to separation of the solid product, such as cooling the product reaction mixture to above or not below the melting point of the excess phosphonic acid and combining it with other solvents as described herein, such as water. As described above, other solvent / slurry mixtures may optionally be stirred. The solid flame retardant product can be separated by filtration, optionally washing with other solvents, and drying to obtain a product in powder or particulate form. The flame retardant product contains phosphorus and aluminum in a phosphorus to aluminum ratio of 4:1 according to the following empirical formula:

[0088] In another example, the above examples utilize iron or suitable iron compounds, such as iron halides, oxides, alkoxides, carbonates, or acetates, for example, iron(III) oxide, iron(III) chloride, iron(III) isopropylidene oxide, or iron(III) acetate. The flame retardant product contains a phosphorus to iron ratio of 4:1 according to the following empirical formula:

[0089]

[0090] Typically, the compound represented by the empirical formula above (in some embodiments, it 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 range therebetween, by weight of the flame retardant product.

[0091] In other embodiments, a suitable metal compound (c) is a metal phosphonate of the following formula:

[0092]

[0093] Where R and M are as described above, p is a value from 2 to 5, such as 2, 3, or 4, and y is a value from 2 to 5, such as 2, 3, or 4, thus M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation. Typically, metal phosphonates are charge-balanced (i.e., p = y). Metal phosphonates can be prepared according to methods known in the art.

[0094] In one example, a phosphonic acid, such as an alkylphosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid), is combined with water (e.g., in a weight ratio of about 1:1) and stirred and cooled to below room temperature (e.g., cooled to or below 10°C, such as about 0°C). An initial metal compound is added to the mixture of phosphonic acid and water to form a metal phosphonate. The metal phosphonate is then used as a suitable metal compound in the methods of this disclosure to produce a flame-retardant product in powder or particulate form. In embodiments involving aluminum phosphonates as suitable metal compounds, the flame-retardant product contains phosphorus and aluminum in a phosphorus to aluminum ratio of 4:1 according to the following empirical formula:

[0095] Typically, the compound represented by the empirical formula (in some embodiments, it 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 range thereof, by weight of the flame retardant product.

[0096] The flame retardant of the present invention can be used with a variety of other flame retardants and / or synergists or flame retardant adjuvants known in the art. For example, the flame retardant of the present invention can be formulated with one or more materials selected from the following:

[0097] Carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes; polyphenylene oxide (PPE), phosphine oxide and polyphosphine oxide, such as benzyl phosphine oxide, polybenzyl phosphine oxide, etc.

[0098] Melamine, melamine derivatives and melamine condensation products, melamine salts, such as but not limited to melamine cyanurate, melamine borate, melamine phosphate, melamine metal phosphate, melamine, melamine, cyanuramide, etc.

[0099] Inorganic compounds, including clay, metal salts such as hydroxides, oxides, oxide hydrates, borates, carbonates, sulfates, phosphates, phosphites, hypophosphites, silicates, mixed metal salts, etc., such as talc and other magnesium silicates, calcium silicates, aluminum silicates, aluminum silicates as hollow tubes (DRAGONITE), calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, halloysite or boron phosphate, calcium molybdate, expanded vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide and zinc borate, zinc molybdate (or its complexes, such as Kemgard 911B), zinc molybdate / magnesium hydroxide complexes (such as Kemgard MZM), zinc molybdate / magnesium silicate complexes (Kemgard 911C), calcium molybdate / zinc complexes (such as Kemgard 911A), zinc phosphate (or its complexes, such as Kemgard 911A), and zinc phosphate (or its complexes, such as Kemgard 911B). 981), magnesium oxide or magnesium hydroxide, aluminum oxide, aluminum hydroxide (Boehmite), aluminum trihydrate, silicon dioxide, tin oxide, antimony oxide (III and V) and oxide hydrates, titanium oxide, as well as zinc oxide or oxide hydrates, zirconium oxide and / or zirconium hydroxide, etc.

[0100] Unless otherwise stated, in the context of this application, when used as a component in "phosphate," such as in metal phosphates, melamine phosphates, melamine metal phosphates, etc., the term "phosphate" refers to phosphate, hydrogen phosphate, dihydrogen phosphate, pyrophosphate, polyphosphate, or anionic or polyanionic phosphate condensation product.

[0101] Similarly, unless otherwise stated, in the context of this application, the term "phosphite" refers to a phosphite or hydrogen phosphite when used as a component in a "phosphite" such as a metal phosphite.

[0102] The flame retardant of the present 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 hypophosphites, and salts of alkyl or aryl hypophosphites. In some embodiments, the flame retardant comprises a mixture of the flame retardant according to the present disclosure and a hypophosphite (e.g., tris(dialkylaluminum hypophosphite)) shown in the following formula.

[0103]

[0104] R1 and R2 can each independently be groups of R as described herein, M is a metal as described herein (e.g., Al or Ca), and n is a value from 2 to 7, for example from 2 to 4, typically 2 or 3.

[0105] In some embodiments, the flame-retardant polymer composition according to the present disclosure comprises (i) a polymer, (ii) the flame-retardant material of the present disclosure, and (iii) one or more other flame retardants and / or one or more synergists or flame-retardant adjuvants.

[0106] For example, in some embodiments, the flame-retardant polymer composition contains one or more other flame retardants, such as halogenated flame retardants, phosphine oxide flame retardants, alkyl or aryl phosphonates, or alkyl or aryl hypophosphinates, such as aluminum tris(dialkylphosphinate), like aluminum tris(diethylphosphinate).

[0107] In some embodiments, the flame-retardant polymer composition comprises one or more synergists or flame-retardant adjuvants, such as melamine, melamine derivatives and melamine condensation products (e.g., melamine, melamine, cyanuramide), melamine salts, phosphine oxides and polyphosphine oxides, metal salts such as hydroxides, oxides, oxide hydrates, borates, phosphates, phosphonates, phosphites, silicates, etc., such as aluminum hydrogen phosphite, melamine, or melamine metal phosphates, such as melamine metal phosphates in which the metal comprises aluminum, magnesium, or zinc. In specific embodiments, one or more other flame retardants, synergists, or flame retardant adjuvants include aluminum tris(dialkylphosphine), aluminum hydrogen phosphite, methylene-diphenylphosphine oxide-substituted polyarylene ether, diphenyl bis(diphenylphosphine oxide), 4,4'-bis(diphenylphosphine oxide methyl)-1,1'-biphenyl, ethylidene bis-1,2-bis-(9,10-dihydro-9-oxo-10-phosphenanthroline-10-oxide) ethane, melamine, melamine, cyanuramide, or zinc di-tricyanamide pyrophosphate.

[0108] Some embodiments provide halogen-free polymer compositions. In these embodiments, halogen-containing flame retardants or synergists will be excluded whenever possible.

[0109] The flame-retardant material of this disclosure can be combined with other flame retardants, synergists, or adjuvants in a weight ratio of 100:1 to 1:100 of the total weight of the flame retardant of this invention to the total weight of the other flame retardants, synergists, and / or adjuvants. In some embodiments, the flame-retardant material of this disclosure is present in a weight ratio of 10:1 to 1:10 of the total weight of the flame retardant of this invention to the total weight of the other flame retardants, synergists, and / or adjuvants, for example, in weight ratios in the ranges of 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 flame retardant of the present invention is usually the main component in such a combination, for example, the flame retardant material of the present invention is in a ratio of 10:1 to 1.2:1 or 7:1 to 2:1 by weight to the total weight of other flame retardants, synergists and / or adjuvants. However, the material of the present invention may also be a minor component of the mixture, for example, in a ratio of 1:10 to 1:1.2 or 1:7 to 1:2.

[0110] The heat-stabilized flame retardant of the present invention can be incorporated into thermoplastic polymers, such as high-temperature polyamides and polyterephthalates, at high temperatures without reducing or adversely affecting the physical properties of the polymer, and the flame retardant activity is excellent. The flame retardant of the present invention can be used in other polymers with other synergists and with conventional polymer additives.

[0111] The polymers in the flame-retardant compositions of the present invention can be any polymer known in the art, such as polyolefin homopolymers and copolymers, rubbers, polyesters including polyalkylene terephthalate, epoxy resins, polyurethanes, polysulfones, polyimides, polyphenylene ethers, styrene polymers and copolymers, polycarbonates, acrylic polymers, polyamides, polyacetals, and biodegradable polymers. Mixtures of different polymers can also be used, such as polyphenylene ether / styrene resin blends, polyvinyl chloride / acrylonitrile butadiene styrene (ABS), or other impact-modified polymers, such as ABS containing methacrylonitrile and α-methylstyrene, and polyester / ABS or polycarbonate / ABS and polyester or polystyrene with some other impact modifiers. These polymers are commercially available or can be prepared by methods well known in the art.

[0112] The flame retardants of the present invention are particularly useful in thermoplastic polymers that are treated and / or used at high temperatures, such as styrene polymers, including high-impact polystyrene (HIPS), polyolefins, polyesters, polycarbonates, polyamides, polyurethanes, polyphenylene ethers, etc.

[0113] For example, the polymer can be a polyester resin, a styrene resin, a polyamide resin, a polycarbonate resin, a polyphenylene ether resin, a vinyl resin, an olefin resin, an acrylic resin, an epoxy resin, or a polyurethane. The polymer can be a thermoplastic or thermosetting resin and can be reinforced, such as glass-reinforced. In some embodiments, the polymer is a thermoplastic polyurethane. In some embodiments, the polymer is a thermosetting epoxy resin. More than one polymeric resin may be present. In specific embodiments, the polymer is an engineering polymer, such as a thermoplastic or reinforced thermoplastic polymer, such as a glass-reinforced thermoplastic polymer, such as optionally glass-filled polyester, epoxy resin, or polyamide, such as glass-filled polyester, such as glass-filled polyalkylene terephthalate, or glass-filled polyamide.

[0114] For example, polyester resins include homopolymers and copolyesters obtained by polycondensation of dicarboxylic acid components and diol components, and polycondensation of hydroxycarboxylic acid or lactone components, such as aromatic saturated polyester resins, like polybutylene terephthalate or polyethylene terephthalate.

[0115] Polyamide (PA) resins include polyamides derived from diamines and dicarboxylic acids; polyamides derived from aminocarboxylic acids, if necessary, in combination with diamines and / or dicarboxylic acids; and polyamides derived from lactams, if necessary, in combination with diamines and / or dicarboxylic acids. Polyamides also include copolyamides derived from at least two different types of polyamide constituent components. Examples of polyamide resins include aliphatic polyamides such as PA46, PA6, PA66, PA610, PA612, PA11, and PA12; polyamides derived from aromatic dicarboxylic acids such as terephthalic acid and / or isophthalic acid and aliphatic diamines such as hexamethylenediamine or nonadiamine; and polyamides derived from both aromatic and aliphatic dicarboxylic acids such as terephthalic acid and adipic acid and aliphatic diamines such as hexamethylenediamine. These polyamides can be used alone or in combination. In some embodiments, the polymer includes PA6. In some embodiments, the polymer includes PA66. In some embodiments, the polymer includes polyphthalamide.

[0116] Polyamides with a melting point of at least 280°C are widely used in the production of molding compositions, enabling the production of molded articles, such as those used in the electrical and electronics industries. These articles exhibit excellent dimensional stability at high temperatures and possess very good flame-retardant properties. For example, this type of molding composition is required in the electronics industry, where components are manufactured for mounting on printed circuit boards using so-called surface mount technology (SMT). In such applications, these components must withstand temperatures up to 270°C for short periods without dimensional changes.

[0117] These high-temperature polyamides include certain polyamides derived as polyamides 4,6 from alkyl diamines and diacids; however, many high-temperature polyamides are aromatic and semi-aromatic polyamides, i.e., derived from homopolymers, copolymers, terpolymers, or higher polymers containing aryl monomers. Monoaromatic or semi-aromatic polyamides can be used, or blends of aromatic and / or semi-aromatic polyamides can be used. The above polyamides and polyamide blends can also be blended with other polymers, including aliphatic polyamides.

[0118] Examples of these high-temperature aromatic or semi-aromatic polyamides include polyamide 4T, poly(hexamethylene isophthalamide) (polyamide MXD, 6), poly(dodecanoyl terephthalamide) (polyamide 12, T), poly(decanoyl terephthalamide) (polyamide 10, T), poly(nonadiamine terephthalamide) (polyamide 9, T), and adipamide / hexamethylene terephthalamide copolyamide (polyamide 6, T / 6, 6). Polyamides such as hexamethylene terephthalamide / 2-methylpentamethylene terephthalamide (polyamide 6,T / D,T), hexamethylene adipamide / hexamethylene terephthalamide / hexamethylene isophthalamide (polyamide 6,6 / 6,T / 6,I), poly(caprolactam-hexamethylene terephthalamide) (polyamide 6 / 6,T), and hexamethylene terephthalamide / hexamethylene isophthalamide (6,T / 6,I) copolymers are available.

[0119] Therefore, certain embodiments of the present invention relate to compositions comprising polyamides molten at high temperatures, such as 280°C or higher, 300°C or higher, and in some embodiments, 320°C or higher, for example 280 to 340°C, such as the polyamides described above, including polyamides 4 and 6, as well as aromatic and semi-aromatic polyamides; articles comprising high-temperature polyamides and the flame-retardant material of the present invention; methods for preparing the compositions; and methods for shaping the articles.

[0120] As described herein, in various embodiments of this disclosure, the flame-retardant polymer composition comprises (i) a polymer, (ii) a flame retardant of this disclosure, and (iii) one or more other flame retardants and / or one or more synergists or flame-retardant adjuvants. Thus, although the flame retardant (ii) alone exhibits excellent activity in the polymer system, it can be used in combination with (iii) one or more compounds selected from other flame retardants, synergists, and adjuvants. Exemplary 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 hypophosphites, salts of alkyl or aryl hypophosphites, carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes, polyphenylene ethers, melamine, melamine derivatives, melamine condensates, 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(dialkylphosphino)phosphate, aluminum hydrogen phosphite, benzylphosphine oxide, polybenzylphosphine oxide, melamine, melamine, cyanuramide, melamine phosphate, melamine metal phosphate, melamine cyanurate, melamine borate, talc, clay, calcium silicate, aluminosilicate, aluminosilicate as a hollow tube, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, boron phosphate, calcium molybdate, expanded vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate, zinc phosphate, magnesium oxide, magnesium hydroxide, aluminum oxide, aluminum hydroxide, aluminum trihydrate, silicon dioxide, tin oxide, antimony oxide (III and V), antimony oxide (III and V) hydrate, titanium oxide, zinc oxide, zinc oxide hydrate, zirconium oxide, and zirconium hydroxide. For example, one or more compounds (iii) may be selected from tris(dimethylphosphonic acid)aluminum, tris(diethylphosphonic acid)aluminum, tris(dipropylphosphonic acid)aluminum, tris(dibutylphosphonic acid)aluminum, methylene-diphenylphosphine oxide-substituted polyarylene ether, diphenyl bis(diphenylphosphine oxide), 1,2-bis-(9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide)ethane, 4,4'-bis(diphenylphosphine oxide methyl)-1,1'-biphenyl, melamine, melamine, cyanuramide and zinc di- and trimelamine pyrophosphate.

[0121] In some embodiments, the flame retardant synergist comprises a material selected from melamine, melamine, cyanuramide, melamine cyanurate, melamine polyphosphate, and melamine-poly(metal phosphate) (e.g., melamine-poly(zinc phosphate) (Safire400)). In some embodiments, the synergist comprises a triazine-based compound, such as the reaction product of trichlorotriazine, piperazine, and morpholine, for example, poly-[2,4-(piperazin-1,4-yl)-6-(morpholin-4-yl)-1,3,5-triazine] / piperazine. PPM Triazine HF). In some embodiments, the synergist includes a metal hypophosphite, such as aluminum hypophosphite (e.g., Italmatch). IP-A). In some embodiments, the synergist includes an organic phosphonate, such as aluminum dialkylphosphonate, for example, aluminum diethylphosphonate (Exolit OP).

[0122] In some embodiments, the flame-retardant polymer composition includes one or more compounds selected from hydrotalcite clay, metal borates, metal oxides, and metal hydroxides, such as metal borates, metal oxides, or metal hydroxides wherein the metal is zinc or calcium.

[0123] The concentration of the flame retardant of the present invention in the polymer composition depends, of course, on the exact chemical composition of the flame retardant, the polymer present in the final polymer composition, and other components. For example, when used as the sole flame retardant component in a polymer formulation, the flame retardant of the present invention may be present at a concentration of 1 to 50% by weight, for example, 1 to 30% of the total weight of the final composition. Typically, when used as the sole flame retardant, at least 2% of the material of the present invention will be present, for example, 3% or higher, 5% or higher, 10% or higher, 15% or higher, 20% or higher, or 25% or higher. In some embodiments, the flame retardant of the present invention is present in an amount of up to 45%, while in other embodiments, the amount of the flame retardant of the present invention is 40% or less of the polymer composition, for example, 35% or less. When used in combination with other flame retardants or flame retardant synergists, a smaller amount of the material of the present invention may be required.

[0124] Any known mixing (blending, compounding) technique can be used to prepare the flame-retardant polymer compositions of this disclosure, for example, by introducing the flame retardant into the molten polymer through blending, extrusion, fiber or film formation, etc. In some cases, the flame retardant is introduced into the polymer during polymer formation or curing; for example, the flame retardant of the present invention can be added to a polyurethane prepolymer before crosslinking, or it can be added to a polyamide or alkyl-polycarboxylic compound before polyamide formation, or to an epoxy mixture before curing.

[0125] The flame-retardant polymer compositions of the present invention typically contain one or more conventional stabilizers or other additives commonly found in the art, such as phenolic antioxidants, hindered amine light stabilizers (HALS), ultraviolet absorbers, phosphites, phosphonites, alkali metal fatty acid salts, hydrotalcite, metal oxides, borates, epoxidized soybean oil, hydroxylamine, tertiary amine oxides, lactones, thermal reaction products of tertiary amine oxides, sulfur synergists, alkaline co-stabilizers such as melamine, melamine, etc., polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, hydrotalcite, alkali metal salts and alkaline earth metal salts of higher fatty acids such as stearic acid (Ca), calcium stearoyl lactylate, calcium lactate, stearic acid (Zn), octanoic acid (Zn), stearic acid (Mg), ricinoleic acid (Na) and palmitic acid (K), antimony pyrocatechol or zinc pyrocatechol, nucleating agents, clarifying agents, etc.

[0126] Other additives may also be present, such as plasticizers, lubricants, emulsifiers, pigments, dyes, optical brighteners, other fire retardants, antistatic agents, foaming agents, and anti-drip agents such as PTFE.

[0127] 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 can typically be present in relatively high concentrations, including formulations in which the filler or reinforcing agent is present at a concentration greater than 50 wt% based on the weight of the final composition. More typically, the filler and reinforcing agent are present at about 5 to about 50 wt%, such as about 10 to about 40 wt%, or about 15 to about 30 wt%, based on the weight of the total polymer composition.

[0128] In some embodiments, the flame-retardant polymer composition of this disclosure is formulated together with one or more materials selected from the following: 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, expanded vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate (or a complex thereof, such as Kemgard 911B), zinc molybdate / magnesium hydroxide complex (such as Kemgard MZM), zinc molybdate / magnesium silicate complex (Kemgard 911C), calcium molybdate / zinc complex (such as Kemgard 911A), zinc phosphate (or a complex thereof, such as Kemgard 981), etc.

[0129] Hydroxides, oxides, and oxide hydrates of Group 2, 4, 12, 13, 14, and 15 (semi-)metals, such as magnesium oxide or magnesium hydroxide, aluminum oxide, aluminum hydroxide (Boehmite), aluminum trihydrate, silicon dioxide, silicates, tin oxide, antimony oxide (III and V) and antimony oxide hydrate, titanium oxide, as well as zinc oxide or zinc oxide hydrate, zirconium oxide, and / or zirconium hydroxide, etc.; melamine and urea-based resins, such as melamine cyanurate, melamine borate, melamine phosphate, melamine pyrophosphate, polyphenylene ether (PPE), etc.; and clays, including hydrotalcite, boehmite, kaolin, mica, montmorillonite, wollastonite, nano-clays, or organically modified nano-clays, etc.

[0130] In some embodiments, the flame-retardant polymer composition of this disclosure is formulated together with one or more materials selected from the following: zinc borate, zinc stannate, polysiloxane, 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 molybdate / zinc complex (e.g., Kemgard 911A), zinc phosphate complex (e.g., Kemgard 981), and melamine-poly(metal phosphate) (e.g., melamine-poly(zinc phosphate) (Safire 400)).

[0131] In some embodiments, in addition to the polymers and flame retardants disclosed herein (as described herein), the flame-retardant polymer composition includes melamine and one or more materials selected from any one of the following: zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium molybdate / zinc complex, zinc phosphate complex, and zinc oxide, optionally and other additives as described herein.

[0132] In some embodiments, in addition to the polymers and flame retardants disclosed herein (as described herein), the flame-retardant polymer composition includes cyanuramide and one or more materials selected from the group consisting of zinc borate, zinc stannate, zinc molybdate complex, zinc molybdate / magnesium hydroxide complex, zinc molybdate / magnesium silicate complex, calcium molybdate / zinc complex, zinc phosphate complex, and zinc oxide, optionally as well as other additives as described herein.

[0133] Other non-limiting disclosures are provided in subsequent embodiments.

[0134] Example

[0135] Example 1

[0136] Methylphosphonic acid (MPA) (3678.8 g, 38.3 mol, 30 eq, 75% aqueous solution) and alumina (130.2 g, 1.28 mol, 1 eq) were mixed at room temperature and limited exothermic reaction (increase of about 2 °C) was observed. The reactor temperature was set to 165 °C and stirred at 200 RPM under atmospheric pressure and nitrogen purging (4 L / min). When no water distillation was observed in the condenser, 1.0 g of seed material, a flame-retardant product produced from MPA and alumina according to this disclosure, was optionally added. The reaction mixture was heated at 165 °C for 3 hours. The product reaction mixture containing the white slurry product was then cooled to about 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The white slurry was then filtered, washed with water (500 mL × 3), and dried to obtain fine crystals in 92% yield. The product has a phosphorus to aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0137]

[0138] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product. Figure 1 Thermogravimetric analysis (TGA) of the product is shown.

[0139] Example 2

[0140] 800 mL of xylene was transferred to a 1 L flask and fitted with a Dean-Stark separator. The solution was heated to 115 °C and methylphosphonic acid (MPA) (33.89 g, 0.35 mol) was added. The acid was dissolved and the temperature was increased so that the solution began to reflux. Alumina (4.01 g, 0.039 mol) was added aliquots over 3 hours. The solution was kept under reflux at 142 °C overnight. The solid product was separated by filtration, washed with DMF (100 mL) and Et₂O (2 × 50 mL), and dried to obtain a fine powder (18.86 g, 71% yield). The product has a phosphorus to aluminum ratio of 4:1 according to the following empirical formula:

[0141]

[0142] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product.

[0143] Example 3

[0144] Methylphosphonic acid (MPA) (2216 g, 23.1 mol, 15 eq, aqueous solution) and aluminum hydroxide (120 g, 1.5 mol, 1 eq) were mixed at room temperature. The reactor temperature was set to 165 °C and stirred at 200 RPM under atmospheric pressure and nitrogen purging (4 L / min). When no water distillation was observed in the condenser, 1.0 g of seed material, a flame-retardant product generated from MPA and aluminum hydroxide according to this disclosure, was optionally added. The reaction mixture was heated at 165 °C for 3 hours. The product reaction mixture containing the white slurry 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 white slurry was filtered, washed with water (500 mL × 3), and dried to obtain fine crystals in approximately 100% yield. The product has a phosphorus to aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0145]

[0146] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product.

[0147] Example 4

[0148]

[0149] Methylphosphonic acid (MPA) (1412.6 g, 14.7 mol, 30 eq, 75% aqueous solution) and iron oxide (78.2 g, 0.49 mol, 1 eq) were mixed at room temperature. The reactor temperature was set to 130 °C for about 12 hours, and the mixture was stirred at 250 RPM under atmospheric pressure and nitrogen purging (4 L / min). The reaction mixture was then heated to 165 °C for 12 hours. The product reaction mixture containing the off-white slurry was then cooled to about 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The off-white slurry was filtered, washed with water (500 mL × 3), and dried to obtain fine off-white crystals in 92% yield. The product had a phosphorus to iron ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0150]

[0151] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product.

[0152] Example 5

[0153]

[0154] Methylphosphonic acid (MPA) (1727 g, 18.4 mol, 15 eq, 75% aqueous solution) was cooled to 5 °C in an ice-water bath under a nitrogen flow (1 L / min). While maintaining the reactor temperature below 10 °C, alumina isopropylidene (250 g, 1.2 mol, 1 eq) was added aliquots. The reactor temperature was then set to 165 °C and stirred at 250 RPM. At 165 °C, optionally 4.5 g of seed material, a flame-retardant product generated from MPA and alumina isopropylidene according to this disclosure, was added, and the reaction mixture was maintained at 165 °C for 3 hours. The product reaction mixture containing the white slurry 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 white slurry was filtered, washed with water (500 mL × 3), and dried to obtain fine crystals in a yield of 44%. The product had a phosphorus to aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0155]

[0156] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product.

[0157] Example 6

[0158]

[0159] Ethylphosphonic acid (EPA) (55.0 g, 0.50 mol, 30 eq) and alumina (1.70 g, 17 mmol, 1 eq) were mixed with 50 mL of water at room temperature. The reactor temperature was set to 165 °C, and the mixture was stirred at 250 RPM under atmospheric pressure and nitrogen purging (4 L / min). The reaction mixture was heated at 165 °C for 3 hours. Then, the product reaction mixture containing the white slurry product was cooled to approximately 130 °C and poured into 100 mL of water in a beaker cooled in an ice-water bath. The white slurry was filtered, washed with water (50 mL × 3), and dried to obtain fine crystals in 76% yield. The product had a phosphorus to aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0160]

[0161] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product.

[0162] Example 7

[0163] Polymer compositions were prepared and their flame retardant activity was evaluated according to UL-94 testing. UL-94 V-0 scores were measured at thicknesses of 0.8 mm and 1.6 mm for glass-filled polymer compositions containing the flame retardant produced according to Example 1 above.

[0164] Table 1. Formulations with UL-94 V-0 rating at 0.8 and 1.6 mm.

[0165] matrix Fiberglass The FR of the present invention Honey amine Zinc borate PA6,6 30wt% 13wt% 10wt% 1wt% PA6,6 30wt% 13.7wt% 10wt% -

[0166] The UL-94V-0 rating at 0.8 mm was also measured for glass-filled polymer compositions containing the flame retardants produced according to Examples 1, 2, 3, and 5 above, including polyamide 6, 6, polyamide 6, polybutylene terephthalate (PBT), and high-temperature polyamide.

[0167] Table 2. Compositions with a UL-94V-0 rating at 0.8 mm

[0168] matrix Fiberglass The FR of the present invention Honey amine melamine cyanurate PA6,6 30％ 12.5％ 10％ - PA6 25％ 15％ - 10％ PBT 25％ 15％ 15％ - High-temperature nylon 25％ 18％ - -

[0169] Other polymer compositions containing flame retardants produced according to Examples 1, 2, 3, and 5 above, in combination with various synergists in glass-filled PA 66, PBT, and polyphthalamide, were prepared and evaluated according to UL-94 testing at a thickness of 0.8 mm. Results are provided in Tables 3 (PA 66), 4 (PBT), and 5 (polyphthalamide). Formulations 17, 22, and 24, which do not contain the flame retardants of this invention, failed the UL-94 test.

[0170] Table 3. PA66

[0171]

[0172]

[0173] Table 4. PBT

[0174]

[0175] Table 5. Phthalate (High-Temperature Polyamide)

[0176]

[0177]

[0178] Example 8

[0179] Polymer compositions containing the flame retardant produced according to Example 4 above were prepared in PA 66, and their flame retardant activity was evaluated according to the UL-94 test at a thickness of 0.8 mm. The results are provided in Table 6. Sample 27, which did not contain the flame retardant of the present invention, failed the UL-94 test.

[0180] Table 6. PA 66

[0181]

[0182] Although specific embodiments of the invention have been shown and described, it will be apparent to those skilled in the art, upon consideration of this specification and practice of this disclosure, that various modifications and alterations can be made without departing from the claimed scope of the invention. Therefore, this specification and embodiments are intended to be considered merely exemplary, and the true scope of the invention is set forth by the appended claims and their equivalents.

Claims

1. A method for producing a phosphorus-containing flame retardant, comprising: Prepare a reaction mixture, the reaction mixture comprising: (a) Unsubstituted or alkyl- or aryl-substituted phosphonic acids, represented by the following formula (I): Where R represents H and C 1-12 Alkyl or C 6-10 Aryl, (b) The solvent used for the phosphonic acid, and (c) A metal selected from Al or Fe, or a suitable metal compound selected from aluminum oxide, aluminum trichloride, aluminum hydroxide, isopropyl alumina, aluminum carbonate, aluminum acetate, iron(III) oxide, iron(III) chloride, isopropyl iron(III) oxide, and iron(III) acetate; and The reaction mixture containing components (a), (b), and (c) is heated at a reaction temperature of 140°C or higher for a sufficient amount of time to produce the phosphorus-containing flame retardant. The components (a) and (b) of the reaction mixture are in solution form, and the preparation of the reaction mixture includes mixing component (c) with the solution. The molar ratio of component (a) to component (c) in the reaction mixture is in the range of 4:1 to 50:

1. The resulting phosphorus-containing flame retardant comprises compounds of formula (III): Where a is 1, b is 1, c is 1, M is Al or Fe, and y is 3.

2. A method for producing a phosphorus-containing flame retardant, comprising: Prepare a reaction mixture, the reaction mixture comprising: (a) Unsubstituted or alkyl- or aryl-substituted pyrophosphonic acids, represented by the following formula (Ia): Where R represents H and C 1-12 Alkyl or C 6-10 Aryl, (b) The solvent used for the pyrophosphonic acid, and (c) A metal selected from Al or Fe, or a suitable metal compound selected from aluminum oxide, aluminum trichloride, aluminum hydroxide, isopropyl alumina, aluminum carbonate, aluminum acetate, iron(III) oxide, iron(III) chloride, isopropyl iron(III) oxide, and iron(III) acetate; and The reaction mixture containing components (a), (b), and (c) is reacted at a reaction temperature of 20°C or higher for a sufficient amount of time to produce the phosphorus-containing flame retardant. The molar ratio of component (a) to component (c) in the reaction mixture is in the range of 4:1 to 50:

1. The resulting phosphorus-containing flame retardant comprises compounds of formula (III): Where a is 1, b is 1, c is 1, M is Al or Fe, and y is 3.

3. The method according to claim 1 or 2, wherein the reaction mixture is prepared at a preparation temperature below the reaction temperature.

4. The method according to claim 3, wherein the preparation temperature is in the range of 15°C to 40°C.

5. The method according to claim 2, wherein components (a) and (b) of the reaction mixture are in solution form, and the preparation of the reaction mixture comprises mixing component (c) with the solution.

6. The method according to claim 1, wherein the reaction temperature is 150°C or higher.

7. The method according to claim 1, wherein the reaction temperature is in the range of 140°C to 260°C.

8. The method according to claim 2, wherein the reaction temperature is 60°C or higher.

9. The method according to claim 2, wherein the reaction temperature is in the range of 60°C to 240°C.

10. The method of claim 1, wherein the solvent is selected from water, sulfone, sulfoxide, halogenated hydrocarbons, aromatic hydrocarbons, and ethers.

11. The method of claim 1, wherein the solvent comprises water.

12. The method of claim 2, wherein the solvent is aprotic.

13. The method according to claim 1 or 2, wherein R is unsubstituted C. 1-6 alkyl.

14. The method of claim 13, wherein R is methyl, ethyl, propyl or butyl.

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