Process for preparation of phosphorus-containing flame retardants with improved powder properties

Abstract

A phosphorus-containing flame retardant is produced by preparing a metal phosphonic acid solution and reacting a reaction mixture of an unsubstituted or alkyl or aryl substituted pyrophosphonic acid with the metal phosphonic acid solution at a reaction temperature of 130 DEG C to 240 DEG C for an amount of time sufficient to produce the phosphorus-containing flame retardant in crystalline form. The resulting flame retardants are stable and have improved powder properties for formulating in polymer compositions, in particular thermoplastics processed at high temperatures, in a wide range of applications.

Description

Technical Field

[0001] Highly effective thermally stable phosphorus-containing flame retardants are produced by a method comprising reacting a phosphonic acid with a metal or suitable metal compound in a solvent to provide a metal phosphonic acid solution, and adding pyrophosphonic acid to the solution under conditions described herein. In many embodiments, the resulting flame-retardant product is produced as one or a major compound with good flowability and powder properties, resulting in excellent flame retardancy and exhibiting high thermal stability. The flame retardants disclosed herein can be used in a wide range of applications, for example, in polymer compositions, particularly in thermoplastics processed at high temperatures. Background Technology

[0002] Salts of phosphonic acids (i.e., compounds of the formula shown below) are known flame retardants in many polymer compositions:

[0003] Where R is an optionally substituted alkyl, aryl, alkylaryl, or aralkyl group, p is typically a number from 1 to 4, M is a metal, and y is typically a number from 1 to 4, such that M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation.

[0004] As disclosed in US 2007 / 0029532, phosphonates are known to decompose at temperatures encountered during the processing of polyesters and polyamides, in which process they damage the polymer, for example, at temperatures above 260°C or 270°C.

[0005] U.S. Patent 5,053,148 discloses that brittle, heat-resistant foams can be obtained by heating phosphonates at elevated temperatures.

[0006] 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 processed at elevated temperatures. A decrease in torque was observed during compounding, consistent with polymer degradation, resulting in a final product material that was brittle upon cooling, pulverized after grinding, and unmoldable. Further evidence of degradation was provided by analysis of the compounded material by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The observed loss of desired polymer properties was consistent with the degradation of the polymer described in US 2007 / 0029532 and the brittle foam formed in U.S. Patent 5,053,148.

[0007] Therefore, simple phosphonates are unsuitable for use in many polymers that are processed at or subsequently exposed to high temperatures (such as 250°C, 260°C, 270°C, or higher) because they undergo chemical transformation at these temperatures through processes that damage the polymer. This can occur during compounding, such as in an extruder, or when the salt is present in the polymer in high-temperature applications.

[0008] On the other hand, U.S. Patent No. 9,745,449 discloses that heating phosphonates at sufficiently high temperatures, typically in the absence of other materials, thermally transforms the salt into different, more thermally stable materials that exhibit excellent flame-retardant activity when incorporated into a polymer matrix. When processed in polymer compositions at elevated temperatures (e.g., 240°C, 250°C, 260°C, 270°C or higher), these thermally transformed materials do not degrade at high temperatures, nor do they cause polymer degradation. This is a significant advantage over previously known phosphonates, which exhibit flame-retardant activity but often degrade polymers during processing. The thermally transformed materials are described as comprising one or more compounds represented by empirical formula (IV): (IV) 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).

[0009] However, the process and materials described in U.S. Patent 9,745,449 present challenges, such as the fact that the produced product is typically in solid, block form and requires grinding, pulverization, or other similar physical treatments 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, embodiments of U.S. Patent 9,745,449 describe the production of phosphorus-containing flame retardants through multiple steps, in which an intermediate metal salt of phosphonic acid is produced, and the salt is then heated and dried at temperatures exceeding 200°C. WO 2020 / 132095 describes an improved method that enables the direct production of flame retardant materials in powder or particulate form by heating the phosphonic acid metal salt in a high-boiling-point, water-miscible, acid-stable solvent (such as sulfone).

[0010] The applicant’s WO 2020 / 132075, WO 2021 / 257749, WO 2021 / 076169, WO 2021 / 257755, WO 2021 / 257756, WO 2023 / 096795 and co-pending application US 63 / 441,482 disclose methods for producing a new class of crystalline flame retardants having formula (III), which are contained in an additive composition for use with thermoplastic polymers.

[0011] (III), Where R is H, alkyl, aryl, alkylaryl, or aralkyl, M is a metal and y is 2 or 3, such that M (+)y It is a metal cation, where (+)y represents the charge formally allocated to the cation, a, b, and c represent the ratios of their corresponding portions in the compound, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero. Crystalline powders produced by this method typically yield average particle sizes of about 20–40 µm (D90) and long crystals with high aspect ratios, such as about 12.5, which can be difficult to formulate in some cases.

[0012] There is a desire for an alternative, energy-efficient method for preparing crystalline phosphorus flame retardants of empirical formula (III) as described above, and particularly compounds of empirical formula (IIIa): (IIIa).

[0013] It is further desirable to provide a method for preparing phosphorus materials having formulas (III) and (IIIa) that have a smaller aspect ratio and a narrower particle size distribution than powders produced according to the applicant’s previously disclosed method.

[0014] This disclosure achieves the above objectives while enabling the production of phosphorus-containing flame retardants without the need for the production or use of intermediate salts as described in U.S. Patent 9,745,449. Summary of the Invention

[0015] According to this disclosure, the phosphorus-containing flame retardant is prepared by a method comprising: preparing a metal phosphonic acid solution; and reacting an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid with the metal phosphonic acid solution at a reaction temperature of 130°C to 240°C for a time sufficient to produce the phosphorus-containing flame retardant.

[0016] In some embodiments, alkyl or aryl-substituted pyrophosphonic acids are prepared by adding a catalytic amount of catalyst to an unsubstituted or alkyl or aryl-substituted phosphonic acid and heating it at a temperature of about 105°C or higher, such as 130°C to 240°C, preferably 180°C to 210°C, for a duration sufficient to produce unsubstituted or substituted pyrophosphonic acids.

[0017] Preferably, prior to the step of reacting the reaction mixture, the method includes removing all or substantially all of any water generated during the preparation of the metal phosphonic acid solution and / or the unsubstituted or substituted pyrophosphonic acid.

[0018] Typically, the reaction product forms as a slurry because the resulting flame-retardant product of the present invention precipitates from the reaction mixture. Any remaining phosphonic acid, pyrophosphonic acid, and / or solvent after the reaction can be removed, along with any possible byproducts, by filtration and / or washing, for example, with water. In many embodiments, substantially pure flame-retardant materials are produced, such as flame retardants that substantially comprise a single compound having flame-retardant activity or a mixture of multiple active compounds substantially having good powder properties for formulation with polymers. The conversion based on metals or metal compounds is typically high, and the product can be readily separated and optionally further purified if desired.

[0019] This method overcomes the difficulties noted in, for example, the method in U.S. Patent 9,745,449, because the generation of, for example, water-soluble or thermally unstable compounds is reduced or avoided, and flame-retardant products crystalline in powder or small particle form can be produced directly in an easily processable form, i.e., without grinding, granulation or other such physical treatments.

[0020] Surprisingly, the method described herein is capable of producing crystalline products of formulas (III) and (IIIa) that exhibit improved powder properties superior to those previously disclosed by the applicant. The products of formulas (III) and (IIIa) prepared by the method herein have reduced aspect ratios as determined by SEM imaging, for example, Aspd90 less than 10, preferably less than 8, more preferably less than 7, or Aspd50 less than 7, preferably less than 5, more preferably less than 4, and narrower particle size distributions. This allows for easier formulation and preparation of flame-retardant polymer compositions.

[0021] Other embodiments of this disclosure include, but are not limited to, phosphorus-containing flame retardants produced according to the methods described herein, such as compounds of formula (III) or (IIIa); 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.

[0022] The foregoing overview is not intended to limit the scope of the claimed invention in any way. Furthermore, it should be understood that both the foregoing general description and the following detailed description are exemplary and illustrative only, and do not limit the scope of the claimed invention. Attached Figure Description

[0023] Figure 1 A scanning electron microscope image of a flame-retardant material produced according to WO 2021 / 076169 is shown.

[0024] Figure 2 A scanning electron microscope image of the flame-retardant material produced according to Example 4 is shown.

[0025] Figure 3 A scanning electron microscope image of the flame-retardant material produced according to Example 6 is shown.

[0026] Figure 4 It is the particle size distribution of flame retardant materials prepared according to WO 2021 / 076169.

[0027] Figure 5 The particle size distribution of the flame-retardant material prepared according to Example 5 is shown.

[0028] Figure 6 A scanning electron microscope image of the flame-retardant material produced according to Example 4 is shown.

[0029] Figure 7 The particle size distribution is based on the flame retardant material produced according to Example 4.

[0030] Figure 8 This is a conversion curve showing the conversion of methylphosphonic acid to pyrophosphonic acid according to Example 10. Detailed Implementation

[0031] Unless otherwise specified, the terms “a” or “an” in this application mean “one or more”.

[0032] Unless the context otherwise requires, the term "alkyl" in this application includes "aranealkyl".

[0033] Unless the context otherwise requires, the term "aryl" in this application includes "alkylaryl".

[0034] As used herein, the term "phosphonic acid" refers to unsubstituted or alkyl- or aryl-substituted phosphonic acids, unless the context otherwise requires.

[0035] As used herein, the term "pyrophosphonic acid" refers to unsubstituted or alkyl- or aryl-substituted pyrophosphonic acids, unless the context otherwise requires.

[0036] The term "aspect ratio" describes how much the overall three-dimensional shape of a particle typically deviates from a compact three-dimensional shape (e.g., a spherical or cubic shape). The aspect ratio of a given particle or group of particles is expressed as the length:width ratio. Particles with a large aspect ratio are typically long and narrow, while particles with an aspect ratio close to 1 are typically dense. By definition, particles cannot have an aspect ratio less than 1.

[0037] As used in this article, the term "Aspd" refers to the aspect ratio of the fraction of particle size distribution, such as D10, D50, or D90.

[0038] As used in this article, D10 or d10 values ​​represent the 10th percentile, D50 or d50 values ​​represent the 50th percentile, and D90 or d90 values ​​represent the 90th percentile. Therefore, D50 corresponds to the median.

[0039] The numerical range listed by endpoints includes all numerical values ​​contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Furthermore, the disclosure of a range includes all subranges contained within a wider range (e.g., 1 to 5 discloses 1-4, 1.5-4.5, 1-2, etc.).

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Materials, methods, and examples are illustrative only and are not intended to be limiting. Many details regarding specific materials and processing behaviors beyond those described herein are conventional and can be found in textbooks and other resources in the field of flame retardants.

[0041] According to one aspect of this disclosure, a metal phosphonic acid solution is reacted with an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid to form a phosphorus-containing flame retardant. The reaction temperature can be in the range of 130°C to 240°C, preferably 190°C to 210°C, more preferably 195°C to 205°C. Due to the limited commercial availability of pyrophosphonic acid and the desire to avoid the presence of any water therein that would cause degradation and reduce reaction yield, the method will typically include preparing the unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid prior to its addition to the reaction mixture with the metal phosphonic acid solution.

[0042] The pyrophosphonic acid prepared and / or used in the method of the present invention can be represented by formula (II): (II), Wherein R is H, alkyl, aryl, alkylaryl, or aralkyl. In many embodiments, R is H, C 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl or C7-18 Aryl alkyl group, wherein the alkyl, aryl, alkylaryl, or aryl alkyl 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 aralkyl group is an unsubstituted C10. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Aryl alkyl groups, such as C 1-6 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 Aryl alkyl groups, for example, C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl or C 7-10 Aryl alkyl group. In many embodiments, R is an unsubstituted C. 1-12 Alkyl, such as C 1-6 Alkyl groups. In many embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0043] 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 as an alkyl group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl. In many embodiments, R is methyl, ethyl, propyl, or isopropyl, such as methyl or ethyl.

[0044] Typically, when R is aryl, it is phenyl. Examples of R as alkylaryl 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 aralkyl include, for example, benzyl, phenethyl, styryl, cumyl, phenylpropyl, etc.

[0045] In many embodiments, R is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl.

[0046] A method for preparing the unsubstituted or alkyl or aryl substituted pyrophosphonic acid may include adding a catalyst to the unsubstituted or substituted phosphonic acid and heating for a sufficient amount of time to produce the unsubstituted or substituted pyrophosphonic acid.

[0047] A heating temperature of 105°C or higher is used. In many embodiments, the catalyst and phosphonic acid react 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 between these. The heating temperature may be higher than those described above, such as up to about 350°C, up to about 400°C or higher, but it typically does not reach or exceed the boiling point of the phosphonic acid. In many embodiments, the heating temperature ranges from about 110°C to about 350°C, from about 115°C to about 300°C, from about 125°C to about 280°C, or from about 130°C to about 290°C. In some preferred embodiments, the heating temperature is from about 180°C to 240°C, more preferably from about 200°C. Water is formed by the 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 (e.g., continuous removal) of water from the reaction mixture. For example, the reaction temperature can be selected above the boiling point of water to the extent necessary to distill off 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, can be used to facilitate the removal of water from the reaction system.

[0048] In some embodiments, when the unsubstituted or substituted phosphonic acid is heated to about 240°C or higher and purged with vacuum or nitrogen, a catalyst may not be necessary to produce pyrophosphonic acid. The nitrogen flow rate is typically about 2 L / min to about 6 L / min, most preferably about 5 L / min.

[0049] Alternatively, when the vacuum is evacuated to below 10 Torr, a catalyst may not be necessary.

[0050] The phosphonic acid used to form pyrophosphonic acid can be represented by formula (I). (I), Wherein R is H, alkyl, aryl, alkylaryl, or aralkyl. In many embodiments, R is H, C 1-12 Alkyl, C 6-10 Aryl, C7-18 alkylaryl or C 7-18 Aryl alkyl group, wherein the alkyl, aryl, alkylaryl, or aryl alkyl 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 aralkyl group is an unsubstituted C10. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Aryl alkyl groups, such as C 1-6 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 Aryl alkyl groups, for example, C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl or C 7-10 Aryl alkyl group. In many embodiments, R is an unsubstituted C. 1-12 Alkyl, such as C 1-6 Alkyl groups. In many embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0051] 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 as an alkyl group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl. In many embodiments, R is methyl, ethyl, propyl, or isopropyl, such as methyl or ethyl.

[0052] Typically, when R is aryl, it is phenyl. Examples of R as alkylaryl 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 aralkyl include, for example, benzyl, phenethyl, styryl, cumyl, phenylpropyl, etc.

[0053] In many instances, R is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl.

[0054] The catalyst used to prepare pyrophosphonic acid can be any Lewis acid that facilitates dehydration. Suitable Lewis acid catalysts include, but are not limited to, iron halides (FeX). n Titanium halide (TiX) n Titanium alkoxide (Ti(OR)4), titanium dioxide (TiO2), aluminum halide (AlX3), aluminum alkoxide (Al(OR)3), tin halide (SnX) n Boron trihalides (BX3), magnesium halides (MgX2), calcium halides (CaX2), and zinc halides (ZnX2) are used as catalysts. Alternatively, alumina can be used as a catalyst. Other suitable catalysts include thionyl chloride (SOCl2), phosphorus pentoxide, concentrated sulfuric acid, and acetic anhydride. The catalyst may be present in the reaction at a catalytic amount ranging from about 0.001 to about 0.5 mol%, and preferably from about 0.01 to 0.1 mol%. In some embodiments, the catalyst is present at a concentration greater than 0.005 to less than 0.5 mol%, or from about 0.01 mol%, or from about 0.025 mol%, or from about 0.05 mol% to about 0.4 mol%, or from about 0.25 mol%, or from about 0.1 mol%, or any range therebetween.

[0055] In the preparation of this metal phosphonic acid solution, the phosphonic acid used can also be represented by formula (I): (I), Wherein R is H, alkyl, aryl, alkylaryl, or aralkyl. In many embodiments, R is H, C 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl or C 7-18 Aryl alkyl group, wherein the alkyl, aryl, alkylaryl, or aryl alkyl 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 aralkyl group is an unsubstituted C10. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Aryl alkyl groups, such as C 1-6 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 Aryl alkyl groups, such as C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl or C 7-10Aryl alkyl group. In many embodiments, R is an unsubstituted C. 1-12 Alkyl, such as C 1-6 Alkyl groups. In many embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0056] 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 as an alkyl group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl. In many embodiments, R is methyl, ethyl, propyl, or isopropyl, such as methyl or ethyl.

[0057] Typically, when R is aryl, it is phenyl. Examples of R as alkylaryl 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 aralkyl include, for example, benzyl, phenethyl, styryl, cumyl, phenylpropyl, etc.

[0058] In many embodiments, R is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl.

[0059] This metal phosphonic acid solution can be prepared from a 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, which react at a temperature above the melting point but below the boiling point of the phosphonic acid to ensure that the solution is maintained and that no metal phosphonate is formed. That is, the metal phosphonic acid should be free of precipitates. Typically, components (a), (b), and (c) are mixed at a temperature ranging from 100°C to 280°C for a time sufficient to ensure that the solution is maintained free of precipitates.

[0060] The solvent (i.e., component (b)) can be any solvent capable of dissolving the phosphonic acid component (a), and the reaction between the phosphonic acid (a) and the metal or suitable metal compound (c) should be inert or substantially inert. Further consideration can be given to selecting other reaction parameters (e.g., preparation and / or reaction temperature, or the type of metal or suitable metal compound) to prepare a homogeneous or substantially homogeneous reaction mixture. In some embodiments, the solvent (b) can be a combination of solvents used for the phosphonic acid to allow the phosphonic acid (a) to dissolve substantially or completely in the solvent (b) and form a solution. The type of solvent, the amount of solvent relative to the phosphonic acid, and the mixing conditions can be selected to achieve the dissolution of the phosphonic acid, such as obtaining a high concentration of phosphonic acid in the mixture while keeping the phosphonic acid in solution. Typically, the weight ratio of the phosphonic acid (a) to the solvent (b) ranges from about 1:3 to 1:50, more preferably from about 1:2.5 to 1:25, and most preferably about 1:2.75. In some embodiments in which the phosphonic acid (a) is partially dissolved and partially suspended or dispersed in the solvent (b), the preparation temperature may be selected to be at or above the melting temperature of the phosphonic acid to liquefy the phosphonic acid suspended or dispersed in the solvent.

[0061] The metal in the metal phosphonic acid solution should be oxidizable and can be obtained from formula M in its corresponding cation form. (+)y Let M be a metal, (+)y represent the charge of the metal cation, and y be 3. Suitable metal compounds can be derived from formula M. p (+)y X q The expression is represented by M, where M is a metal, (+)y represents the charge of the metal cation, y is 3, X is an anion, and the values ​​of p and q provide the charge balance of the metal compound.

[0062] As described above, depending on the boiling temperature of the solvent used for the phosphonic acid (i.e., component b), at least a portion of the solvent can evaporate from the mixture upon heating. In some embodiments, all, substantially all, or at least most of the solvent (b) evaporates during heating. Solvent (b) may 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 a temperature at or below the heating temperature, such that at least a portion of the solvent evaporates during the heating of the mixture, for example, where all, substantially all, or most of the solvent evaporates. This temperature can be selected to be equal to or higher than the melting temperature of the phosphonic acid to ensure that it remains in liquid form when the solvent evaporates.

[0063] Suitable solvents can be organic or inorganic. Examples of suitable solvents for this phosphonic acid 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.

[0064] In some embodiments, the solvent (b) is a protic solvent (e.g., water) and the mixture system is designed to facilitate the removal of the protic solvent during heating of the mixture, such as continuous removal. For example, the mixing temperature can be selected to be equal to or higher than the boiling temperature of the protic solvent, to the extent necessary to boil at least a portion or a desired amount (e.g., most, substantially all, or all) of the protic solvent during mixing. In some embodiments, the solvent is water and the 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. Additional means (such as gas purging, vacuum, and / or other known means) can be used to facilitate the removal of water from the system. The mixing temperature can also be selected to be at or above the melting temperature of the phosphonic acid, but should be below the boiling point of the phosphonic acid to avoid the formation of metal salts.

[0065] As used in this article, "suitable metal compound" refers to a compound having the formula M p (+)y X q The compound, wherein M is a metal capable of forming polycations, such as a metal forming a 3+ cation, and X is any anion that provides charge balance with metal M. Suitable examples of X include, but are not limited to, anions that form oxides, halides, alkoxides, 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, as described herein, unsubstituted metal M is used. Examples of suitable metals (M) include, but are not limited to, B, Al, Ga, In, Tl, Zr, Ti, Cu, Fe, Co, Ga, Bi, Mn, Cr, Sb, Rh, and Y. In some instances, M is selected from Al, Ga, Sb, Fe, Co, B, and Bi. In some preferred embodiments, M is Al or Fe, with Al being most preferred.

[0066] 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, metal-boron bonds, etc., such as oxides, halides, alkoxides, hydroxides, carboxylates, carbonates, phosphonates, hypophosphonates, phosphonites, phosphates, phosphites, nitrates, nitrites, borates, hydrides, sulfonates, sulfates, sulfides, etc.

[0067] In some embodiments, the metal M of the metal or suitable metal compound is aluminum or iron. In some embodiments, suitable metal compounds are selected from aluminum halides, oxides, hydroxides, alkoxides, carbonates, carboxylates, and phosphonates. In some embodiments, suitable metal compounds are selected from aluminum halides, oxides, hydroxides, and alkoxides. In some embodiments, suitable metal compounds are selected from alumina, aluminum trichloride, aluminum hydroxide, aluminum isopropoxide, aluminum carbonate, and aluminum acetate. In other embodiments, suitable metal compounds are selected from iron halides, oxides, alkoxides, carbonates, and acetates. In some embodiments, suitable metal compounds are selected from iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, and iron(III) acetate.

[0068] The mixture of (a), (b), and (c) can be prepared in any manner suitable for combining or mixing (a) an unsubstituted or alkyl- or aryl-substituted phosphonic acid, (b) a solvent for the phosphonic acid, and (c) the metal or a suitable metal compound. For example, these components can be combined simultaneously or at different times and at different temperatures. In some embodiments, the metal or a suitable metal compound (c) is added to the mixture of the phosphonic acid (a) and the solvent (b) (e.g., a solution). The metal or a suitable metal compound (c) can be added to the mixture all at once or in portions. Similarly, a mixture of phosphonic acid (a), solvent (b), or phosphonic acid (a) and solvent (b) (e.g., a solution) can be added to the mixture all at once or in portions.

[0069] Similarly, the reaction mixture of the metal phosphonic acid and pyrophosphonic acid can be prepared in any manner suitable for combining or mixing the unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid with the metal phosphonic acid solution. For example, these components can be combined simultaneously or at different times. The pyrophosphonic acid can be added to the reaction mixture once or in portions. Similarly, the phosphonic acid metal solution can be added to the reaction mixture once or in portions.

[0070] The method disclosed herein may use more than one phosphonic acid, more than one pyrophosphonic acid, or a combination of phosphonic acid and pyrophosphonic acid.

[0071] The reaction temperature of 130°C to 240°C used to produce the phosphorus-containing flame retardant according to this disclosure promotes the formation of monoanionic and / or dianionic pyrophosphonic acid ligands in the reaction products in a more energy-efficient manner than previous methods. In many embodiments, the metal phosphonic acid solution and pyrophosphonic acid react at temperatures below 240°C, such as below 230°C, below 220°C, below 210°C, or below 205°C, and the system is not required to be designed to promote the removal of water and solvent.

[0072] As described above, the reaction mixture is heated at the reaction temperature or allowed to react for a sufficient amount of time to produce a phosphorus-containing flame retardant. Typically, the flame-retardant product will precipitate from the reaction mixture, and the reaction must proceed for a sufficient time to achieve this precipitation. Generally, the amount of time required to achieve at least substantial 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. Advantageously, heating at the reaction temperature or the reaction occurring lasts only about 0.1 to about 1 hour, for example about 20 minutes, about 10 minutes, about 15 minutes, or about 5 minutes, but other durations may be used.

[0073] In many embodiments, the molar ratio of the pyrophosphonic acid to the metal in the reaction mixture is greater than 2:1, for example, about 3:1 or higher, about 4:1 or higher, or about 5:1 or higher. In many embodiments, the molar ratio is from about 2:1, from about 2.5:1 to about 3:1.

[0074] The reaction mixture can be prepared at a temperature below the reaction temperature, such as room temperature, or alternatively at the reaction temperature. That is, the reaction mixture is prepared by combining the phosphonic acid metal solution with pyrophosphonic acid at the reaction temperature. For example, in some embodiments, preparing the reaction mixture involves preheating the pyrophosphonic acid to the reaction temperature and combining it with the metal phosphonic acid solution.

[0075] After the reaction, the product reaction mixture is cooled to ensure that the pyrophosphonic acid remains in liquid form. Excess pyrophosphonic acid and solvent (if present in the product reaction mixture) can be removed by filtration / washing and optionally recovered. The recovered excess pyrophosphonic acid and / or solvent can be recycled, for example, returned to the reactor where the metal phosphonic acid solution reacts with the pyrophosphonic acid. The flame retardant product is often separated by filtration, optionally followed by further post-treatment (e.g., washing, drying, sieving, etc.). The resulting crystalline flame retardant product, typically in powder or granular form, is readily processable, i.e., requires little or no grinding, pulverization, or other such physical processing before use. It should be understood that the method according to this disclosure produces the flame retardant material "directly" as powder or granules, which allows for processing of the reaction product, such as separating the flame retardant product (e.g., separating the flame retardant product from the remaining solvent), which may include processing the reaction product, for example, by filtration, sieving, washing, drying, etc.

[0076] The methods disclosed herein primarily produce crystalline flame retardants comprising one or more metals and two 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, or a mixture of monoanionic and dianionic ligands, are obtained.

[0077] The crystalline products prepared by the methods described herein have a reduced aspect ratio, as determined by SEM imaging, for example, Aspd90 less than 10, preferably less than 8, more preferably less than 7, or Aspd50 less than 7, preferably less than 5, more preferably less than 4, and a narrower particle size distribution compared to the applicant's WO 2020 / 132075, WO 2021 / 257749, WO 2021 / 076169, WO 2021 / 257755, 2021 / 257756 and co-pending applications PCT / US 2022 / 050062 and US 63 / 441,482. The reduced aspect ratio and narrower particle size distribution provide advantages in the formulation and preparation of flame-retardant polymer compositions. Furthermore, the methods described herein produce less fine powder, which also provides advantages in formulation and preparation.

[0078] This method can produce mixtures of flame-retardant compounds; however, in many instances, the flame-retardant material produced by this method is one or primarily a compound having formula (III) with a high conversion rate based on that metal or metal compound, such as at least 70%, 80%, 85%, 90%, 95%, 98% or higher, or any range thereof, which contrasts with some prior art methods that obtain mixtures of compounds by heat treatment involving metal phosphonates. In general embodiments, the reaction typically proceeds as follows: , Where M is a metal cation and (+)y represents the charge of the cation, for example, M is a trication metal; X is one or more anionic ligands attached to the metal and the stoichiometry of M and X (i.e., p and q) provides a charge balance metal compound; R is H, alkyl, aryl, alkylaryl, or aralkyl; a, b, and c represent the ratios of their corresponding portions in the reaction product relative to each other, and y, a, b, and c are values ​​that provide a charge balance product, provided that neither a nor c can be 0.

[0079] In some preferred embodiments, the method for preparing the pyrophosphonic acid includes the following steps:

[0080] In another aspect, the flame retardant products produced according to this disclosure in powder or particulate form comprise compounds of empirical formula (III) or mixtures of different compounds: (III), Where R is H, alkyl, aryl, alkylaryl, or aralkyl group, a, b, and c represent the ratio of their corresponding portions in the compound, and a is typically a number from 0 to 8, such as 0 to 6, 0 to 4, or 0 to 2; c is typically a number from 1 to 10, such as 1 to 8, 1 to 6, 1 to 4, or 1 to 2; M is a metal; y is 3; and M... (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation. The values ​​of a, b, and c can vary, but the charge balance equation 2(a) + c = b(y) will be satisfied. The value of b is limited only in that it must satisfy the aforementioned equation, and in many embodiments, b is a number from 1 to 4, for example, 1 or 2. In some embodiments, a is 1 or 2, c is 1 or 2, and the product is charge balanced.

[0081] In some implementations, M (+)yIt 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.

[0082] As demonstrated in the embodiments disclosed herein, when using the methods of this disclosure, the phosphorus to aluminum ratio or phosphorus to iron ratio in the resulting flame-retardant product is 4:1. Such a phosphorus to metal ratio achieves high efficiency and allows for reduced loading when compounded into thermoplastic polymers.

[0083] Similar to inorganic coordination compounds, the reaction products in the above reactions and the compounds of empirical formula (III) are ideal, such that the reaction products or compounds can be coordination polymers, complex salts, salts in which some atoms share valences, etc.

[0084] For example, in many embodiments, empirical formula (III) as described herein represents the monomer unit (i.e., coordination entity) of the coordination polymer, the extended coordination polymer structure thereby forming the flame retardant compound of this disclosure.

[0085] Preferably, where M is Al and y is 3, a compound having empirical formula (III) is produced according to the following empirical formula (IIIa): (IIIa).

[0086] As shown herein, the absence of subscripts a, b, and c in the empirical formula indicates that each of these subscripts is 1, thus representing a ratio of 1:1:1 for these components (in the case of empirical formula (IIIa), the ratio of dianionic pyrophosphonic acid ligand, metal atom, and 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 this extended coordination polymer structure forms the flame retardant compound of this disclosure.

[0087] Typically, compounds having empirical formula (III) (e.g., (IIIa)) are, in many embodiments, extended coordination polymers as described herein, constituting all, substantially all, or at least most of the flame retardant product, for example, at least 75%, 85%, 90%, 95%, 98%, or more, or any range thereof, by weight of the flame retardant product.

[0088] Compounds having empirical formula (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., the reaction product is produced using aluminum or one or more aluminum compounds (as described herein)) or iron (i.e., the reaction product is produced using iron or one or more iron compounds (as described herein)).

[0089] In some embodiments, as shown herein, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al or Fe. In other embodiments, X is oxygen, hydroxyl, alkoxy, or halogen.

[0090] The reactions described herein can, but do not need to, be carried out under reduced pressure or vacuum.

[0091] The product reaction mixture (typically presented as a slurry) formed by the reaction described herein can be combined with an additional solvent, which may be the same as or different from the solvent used in preparing the metal phosphonic acid solution. This additional solvent may, for example, be selected from those described herein for solvent component (b). The additional solvent / slurry mixture may be stirred as needed to break up any clumps that may have formed. The solid product may be separated by filtration, optionally washed, and dried to produce a product in powder or fine particle form. In some cases, the product may be sieved to refine the particle size.

[0092] Advantageously, the solid product produced prior to any sieving is a crystalline material with a larger average particle size, a smaller aspect ratio than the material produced according to the previously disclosed method, and also has a narrower particle size distribution (with fewer fine particles) than the material produced according to the previously disclosed method.

[0093] The reaction described herein can optionally be promoted with a seeding material. For example, the use of a seeding material can reduce the time required to achieve the conversion to the flame-retardant product and can result in increased uniformity of the physical properties of the product. Therefore, in some embodiments, the reaction mixture also contains a seeding material (d). Typically, the seeding material is added to the reaction mixture while or after heating to the reaction temperature. In many embodiments, the seeding material is added prior to the conversion and / or precipitation of the flame-retardant product. In some embodiments, the seeding material comprises a flame-retardant material produced according to the method of this disclosure, such as a flame-retardant compound having empirical formula (III) or (IIIa) as described herein. The seeding material can be selected or refined to have a desired particle size.

[0094] In some embodiments, the method provides a material having formula (IIIa) with a median particle size D50 of about 30 µm to 35 µm, as determined using a laser scattering analyzer.

[0095] In some embodiments, the method provides a material having formula (IIIa) with a median aspect ratio Aspd50 of less than 7, preferably less than 5, more preferably less than 4, as determined by SEM imaging. In some of these embodiments, Aspd90 is less than 10, preferably less than 8, more preferably less than 7.

[0096] In some embodiments, a suitable metal compound is aluminum oxide, and the flame-retardant material is produced as follows:

[0097] In one instance, the reaction mixture contains pyrophosphonic acid, such as C1-C 12 Alkyl pyrophosphonic acids (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acids); and solutions of oxides, hydroxides, halides, alkoxides, carbonates, or carboxylates of Al, such as alumina, aluminum trichloride, aluminum hydroxide, aluminum isopropoxide, aluminum carbonate, or aluminum acetate in phosphonic acids (e.g., C1-C12). 12 A solution of an alkylphosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid) is used to heat the reaction mixture to a reaction temperature as described herein, such as about 130°C to 240°C, about 190°C to about 210°C, about 195°C to about 205°C, or about 200°C. Typically, as the reaction proceeds, a slurry forms, and the solid flame retardant product can be separated by filtration to produce a crystalline product. Prior to separating the solid product, further treatment of the product reaction mixture may be performed, such as cooling the product reaction mixture to above or not below the melting point of the excess phosphonic acid and combining it with another solvent (e.g., water) as described herein. The additional solvent / slurry mixture may optionally be stirred as described above. The solid flame retardant product can be separated by filtration, optionally washed with another solvent, and dried to produce a crystalline product. The flame retardant product comprises phosphorus and aluminum in a phosphorus to aluminum ratio of 4:1, according to the following empirical formula: .

[0098] The examples described above can be made with iron or suitable iron compounds, such as iron halides, oxides, alkoxides, carbonates, or acetates, for example, iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, or iron(III) acetate. According to the following empirical formula, the resulting flame retardant product contains phosphorus and iron in a ratio of 4:1: .

[0099] Typically, compounds having the above empirical formula (in many instances, extended coordination polymers as described herein) constitute all, substantially all, or at least most of the flame retardant product, for example, at least 75%, 85%, 90%, 95%, 98%, or more, or any range thereof, by weight of the flame retardant product.

[0100] The flame retardant of the present invention can be used in conjunction 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: Carbon black, graphite, carbon nanotubes, siloxanes, polysiloxanes; polyphenylene oxide (PPE), phosphine oxide and polyphosphine oxide, such as benzyl phosphine oxide, polybenzyl phosphine oxide, etc. 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. Inorganic compounds, including clays, 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, aluminosilicates, aluminosilicates as hollow tubes (DRAGONITE), calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, halloysite or boron phosphate, calcium molybdate, platy vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide and zinc borate, zinc molybdate (or its complexes, e.g. Kemgard 911B), zinc molybdate / magnesium hydroxide complexes (e.g., Kemgard MZM), zinc molybdate / magnesium silicate complexes (Kemgard 911C), calcium molybdate / zinc complexes (e.g., Kemgard 911A), zinc phosphate (or its complexes, e.g., Kemgard 911B), zinc molybdate / magnesium hydroxide complexes (e.g., Kemgard MZM), zinc molybdate / magnesium silicate complexes (Kemgard 911C), calcium molybdate / zinc complexes (e.g., Kemgard 911A), zinc phosphate (or its complexes, e.g., Kemgard 911B), and zinc phosphate (or its complexes, e.g., 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 dioxide, zinc oxide or hydrated oxides, zirconium oxide and / or zirconium hydroxide, etc.

[0101] Unless otherwise specified, in the context of this application, when used as a part in "phosphate" (such as in metal phosphate, melamine phosphate, melamine metal phosphate, etc.), the term "phosphate" means phosphate, hydrogen phosphate, dihydrogen phosphate, pyrophosphonate, polyphosphate, or anionic or polyanionic phosphate condensation product.

[0102] Similarly, unless otherwise specified, in the context of this application, when used as a part of "phosphite," such as in metal phosphites, the term "phosphite" refers to a phosphite or hydrogen phosphite.

[0103] 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 hypophosphinates, and salts of alkyl or aryl hypophosphinates. In some embodiments, the flame retardant comprises a mixture of the flame retardant according to the present disclosure and a hypophosphinate of the following formula (e.g., tris(dialkylphosphinate)aluminum). .

[0104] R1 and R2 can each be independently a group of 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, for example from 2 to 4, usually 2 or 3.

[0105] In many 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 additional flame retardants and / or one or more synergists or flame-retardant adjuvants.

[0106] For example, in some embodiments, the flame-retardant polymer composition comprises one or more additional flame retardants, such as halogenated flame retardants, phosphine oxide flame retardants, alkyl or aryl phosphonates or salts of alkyl or aryl phosphonates, such as aluminum tris(dialkylphosphonates), such as aluminum tris(diethylphosphonates).

[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, wherein the metal includes aluminum, magnesium or zinc. In specific embodiments, the one or more additional flame retardants, synergists, or flame retardant adjuvants include aluminum tris(dialkylphosphino)phosphate, aluminum hydrogen phosphite, methylene-diphenylphosphine oxide-substituted polyarylene ethers, xylene-bis(diphenylphosphine oxide), 4,4'-bis(diphenylphosphonomethyl)-1,1'-biphenyl, ethylene-bis-1,2-bis-(9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide)ethane, melamine, melamine, cyanuramide, or zinc di-tricyanamide pyrophosphonate. In other embodiments, the synergist is at least one metal hypophosphite having the following formula: Me (+)n (H2PO2) n , Where Me is a metal cation, (+)n represents the oxidation state of the metal cation and n is 2 or 3, such as calcium hypophosphite or aluminum hypophosphite.

[0108] Some embodiments provide a halogen-free polymer composition. In these embodiments, halogen-containing flame retardants or synergists are excluded whenever possible.

[0109] The flame-retardant material disclosed herein can be combined with other flame retardants, synergists, or adjuvants, wherein the weight ratio of the flame retardant of this invention to the total weight of the other flame retardants, synergists, and / or adjuvants is in the range of 100:1 to 1:100. In some embodiments, the flame-retardant material of this disclosure is present in a weight ratio of the flame retardant of this invention to the total weight of the other flame retardants, synergists, and / or adjuvants in the range of 10:1 to 1:10, 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 flame retardant of the present invention is usually the main component in such a combination, for example, the weight ratio of the flame retardant material of the present invention to the total weight of other flame retardants, synergists and / or adjuvants is 10:1 to 1.2:1 or 7:1 to 2:1. 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 thermally stable flame retardant of the present invention can be blended into thermoplastic polymers, such as high-temperature polyamides and polyterephthalates, at high temperatures without decomposition or adversely affecting the physical properties of the polymer, and exhibits excellent flame retardant activity. The flame retardant of the present invention can be used in other polymers with other synergists and conventional polymer additives.

[0111] The polymer 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 terephthalates, 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. Such polymers are commercially available or prepared by means well known in the art.

[0112] The flame retardants of the present invention are particularly useful in thermoplastic polymers processed 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, for example, glass-reinforced. In some embodiments, the polymer is a thermoplastic polyurethane. In some embodiments, the polymer is a thermosetting epoxy resin. More than one polymer resin may be present. In certain embodiments, the polymer is an engineering polymer, for example, 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] Polyester resins include homopolymers and copolyesters obtained by polycondensation of, for example, 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 obtained from aminocarboxylic acids, combined with diamines and / or dicarboxylic acids if necessary; and polyamides derived from lactams, combined with diamines and / or dicarboxylic acids if necessary. The polyamide also includes copolyamides derived from at least two different types of polyamide components. Examples of polyamide resins include aliphatic polyamides such as PA 46, PA 6, PA 66, PA 610, PA 612, PA 11, and PA 12; polyamides obtained from aromatic dicarboxylic acids (e.g., terephthalic acid and / or isophthalic acid) and aliphatic diamines (e.g., hexamethylenediamine or nonamethylenediamine); and polyamides obtained from aromatic dicarboxylic acids and aliphatic dicarboxylic acids (e.g., terephthalic acid and adipic acid) and aliphatic diamines (e.g., hexamethylenediamine) and others. These polyamides can be used alone or in combination. In some embodiments, the polymer comprises PA6. In some embodiments, the polymer comprises PA66. In some embodiments, the polymer comprises 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 that exhibit excellent dimensional stability at high temperatures and very good flame retardancy, for example, in the electrical and electronics industries. This type of molding composition is required, for example, in the electronics industry for the production of components mounted on printed circuit boards using so-called surface mount technology (SMT). In this application, these components must withstand temperatures up to 270°C for short periods without dimensional changes.

[0117] Such high-temperature polyamides include some polyamides produced from alkyl diamines and diacids, such as polyamides 4 and 6; however, many high-temperature polyamides are aromatic and semi-aromatic polyamides, i.e., homopolymers, copolymers, trimers, or higher polymers derived from monomers containing aromatic groups. Single aromatic or semi-aromatic polyamides or blends of aromatic and / or semi-aromatic polyamides can be used. The aforementioned 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(adipoxymethylenediamine) (polyamide MXD, 6), poly(terephthaloyldodecanediamine) (polyamide 12, T), poly(terephthaloyldecanediamine) (polyamide 10, T), poly(terephthaloylnonadiamine) (polyamide 9, T), and adipoxyhexamethylenediamine / terephthaloylhexamethylenediamine copolyamide (polyamide 6, T / 6, 6). Polyamides containing hexamethylene terephthalamide / 2-methylpentamethylene terephthalamide (polyamide 6,T / D,T); hexamethylene adipamide / hexamethylene terephthalamide / hexamethylene isophthalamide copolyamide (polyamide 6,6 / 6,T / 6,I); poly(caprolactam-hexamethylene terephthalamide) (polyamide 6 / 6,T); hexamethylene terephthalamide / hexamethylene isophthalamide (6,T / 6,I) copolymer; etc.

[0119] Therefore, some embodiments of the present invention relate to compositions of polyamides, such as polyamides 4, 6 and the aromatic and semi-aromatic polyamides described above, that melt at high temperatures (e.g., 280°C or higher, 300°C or higher, and in some embodiments, 320°C or higher, such as 280°C to 340°C), articles comprising high-temperature polyamides and flame-retardant materials of the present invention, methods for preparing compositions, and methods for molding articles.

[0120] As described herein, in many instances of this disclosure, the flame-retardant polymer composition comprises (i) a polymer, (ii) a flame retardant of this disclosure, and (iii) one or more additional flame retardants and / or one or more synergists or flame-retardant adjuvants. Thus, while 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, the one or more compounds (iii) may be selected from aluminum tris(dialkylphosphine), 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, 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 dioxide, 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 ethers, xylene-bis(diphenylphosphine oxide), 1,2-bis-(9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide)ethane, 4,4'-bis(diphenylphosphonomethyl)-1,1'-biphenyl, melamine, melamine, cyanuramide, and zinc di-tricyanamide pyrophosphonate.

[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) (Safire 400)). In some embodiments, the synergist comprises a triazine compound, such as a 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 (MCA) ® PPM Triazine HF). In some embodiments, the synergist comprises a metal hypophosphite, such as aluminum hypophosphite (e.g., Italmatch Phoslite). ® IP-A) or calcium hypophosphite (e.g., Phoslite) ® B85CX). In some embodiments, the synergist comprises an organic phosphonate, such as aluminum dialkylphosphonate, for example, aluminum diethylphosphonate (Exolit OP).

[0122] In some embodiments, the flame-retardant polymer composition comprises 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 on the exact chemical composition of the flame retardant, the polymer, and other components identified in the final polymer composition. 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 35% by weight of the total weight of the final composition, for example, 1% to 30%. 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 more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more. In many embodiments, the flame retardant of the present invention is present in an amount 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, less of the material of the present invention may be required.

[0124] Any known blending technique can be used to prepare the flame-retardant polymer compositions of this disclosure. For example, the flame retardant can be introduced 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 the polyurethane prepolymer before crosslinking, or it can be added to the polyamine or alkyl polycarboxylic compound before polyamide formation, or to the epoxy mixture before curing.

[0125] The flame-retardant polymer compositions of the present invention will typically contain one or more commonly used stabilizers or other additives frequently encountered in the art, such as phenolic antioxidants, hindered amine light stabilizers (HALS), ultraviolet absorbers, phosphites, phosphonites, alkali metal salts of fatty acids, hydrotalcite, metal oxides, borates, epoxidized soybean oil, hydroxylamine, tertiary amine oxides, lactones, thermal reaction products of tertiary amine oxides, thiosynergists, basic co-stabilizers (e.g., 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 (e.g., calcium stearate, calcium stearoyl lactate, calcium lactate, zinc stearate, zinc octanoate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony catechol or zinc catechol), nucleating agents, clarifying agents, etc.

[0126] In some embodiments, the stabilizer is at least one carbodiimide, and the at least one carbodiimide is preferably of formula (V), (VI), or (VII): (V) Where R 1 and R 2 Independently hydrogen or C1-C 10 Alkyl, C6-C 12 Aryl, C7-C 13 Aryl or C7-C 13 Alkyl, a and b are independent integers from 1 to 5, and c and d are independent integers from 0 to 10; (VI) Where R 4 It is NCO. R 5 R 6 R 7 R 8 R 9 R 10 R 11 R 12 Independently hydrogen or C1-C 10 Alkyl, C6-C 12 Aryl, C7-C 13 Aryl or C7-C 13 Alkyl, g is an integer from 0 to 5, and h is an integer from 1 to 100; (VII) Where m is an integer from 1 to 5000, R 3 It is an arylene, an alkyl-substituted arylene, an alkyl-substituted arylene, or an aralkyl-substituted arylene. R' is aryl, alkylaryl, aralkyl, or R 3 -NCO, and R” is -N=C=N-aryl, -N=C=N-alkylaryl, -N=C=N-aralkyl, or -NCO.

[0127] In some of these embodiments, the carbodiimide is of formula (V) and R 3 Selected from triaryl, C1-C 12 Alkyl-substituted arylene, C7-C 18 Alkyl-substituted arylene, C7-C 18 Aryl-substituted arylene groups and C1-C groups containing a total of 7 to 30 carbon atoms 12 Alkyl-substituted C1-C8 alkylene-bridged arylene, for example, where R 3 yes , where R 13 R 14 and R 15 It is independently a C1-C3 alkyl group. In other embodiments, the carbodiimide is of formula (VI): (VIII) Where R 13 R 14 and R 15 Independently, it is a C1-C3 alkyl group, R 16 It is -NCO, and n is between 0 and 200, for example, where R 13 R 14 and R 15 Each is independently methyl, ethyl, or isopropyl or R 13 R 14 and R 15 Each is independently methyl, ethyl, or isopropyl. In other embodiments, the carbodiimide is of formula (IX) or (X): (IX), (X) In equation (VII), R is -NCO, and n is an integer from 1 to 200.

[0128] In some embodiments, the stabilizer may be at least one epoxy compound, such as an epoxide having at least two epoxy groups. The epoxide may be a polyglycidyl ether or a poly(β-methylglycidyl) ether or a phenolic varnish resin derived from it.

[0129] Other additives may also be present, such as plasticizers, lubricants, emulsifiers, pigments, dyes, optical brighteners, other refractories, antistatic agents, foaming agents, anti-dripping agents (e.g., PTFE), etc. In some of these embodiments, the phenolic varnish resin is selected from cresol phenolic varnish resin, bisphenol A phenolic varnish resin, and bisphenol F phenolic varnish resin. In other embodiments, the epoxy compound is a phenolic varnish polyglycidyl ether, such as the phenolic varnish polyglycidyl ether of formula (XI): (XI) In formula (III), R is independently selected from the group consisting of hydrogen, halogen, alkyl, alkoxy, aryl, alkylaryl, and aralkyl, and n is from 0 to 1000. In some embodiments, R in formula (III) is a C1-C4 alkyl group. The epoxy compound can also be a polyglycidyl ether of the cresol phenolic varnish of formula (XII): (XII) Where n is between 0 and 100 and represents the mean; or the oligomerization product of bisphenol A and epichlorohydrin of formula (XIII): (XIII) Where a is between 0 and 100 and represents the average.

[0130] 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. Such 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 exceeding 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% based on the weight of the total polymer composition, for example, about 10 to about 40 wt% or about 15 to about 30 wt%.

[0131] In some embodiments, the flame-retardant polymer compositions of this disclosure are formulated 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, flake vermiculite, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc borate, zinc molybdate (or its complexes, such as Kemgard 911B), zinc molybdate / magnesium hydroxide complexes (e.g., Kemgard MZM), zinc molybdate / magnesium silicate complexes (Kemgard 911C), calcium molybdate / zinc complexes (e.g., Kemgard 911A), zinc phosphate (or its complexes, such as Kemgard 981), etc. 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 oxide hydroxide (boehmite), aluminum trihydrate, silicon dioxide, silicates, tin oxide, antimony oxide (III and V) and oxide hydrates, titanium dioxide and zinc oxide or oxide hydrates, zirconium oxide and / or zirconium hydroxide, etc.; melamine and urea resins, such as melamine cyanurate, melamine borate, melamine polyphosphate, melamine pyrophosphonate, polyphenylene ether (PPE), etc.; and clays, including, for example, hydrotalcite, boehmite, kaolin, mica, montmorillonite, wollastonite, nanoclays, or organically modified nanoclays, etc.

[0132] In some embodiments, the flame-retardant polymer compositions of this disclosure are formulated 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)).

[0133] In some embodiments, in addition to the polymer (as described herein) and the flame retardant of this disclosure, the flame-retardant polymer composition comprises 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 having additional additives as described herein.

[0134] In some embodiments, in addition to the polymer (such as those described herein) and the flame retardants of this disclosure, the flame-retardant polymer composition comprises 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 having additional additives as described herein.

[0135] Further non-limiting disclosures are provided in the following embodiments.

[0136] Example

[0137] Example 1 – Comparison Method

[0138] MPA (1441 g, 30 equivalents, fresh aqueous solution, using DK-FR12075, 74.7% MPA solution, filtered through a size D glass frit funnel) and Al2O3 (51.0 g, 0.50 mol, 1.0 equivalents) were mixed at room temperature. The reactor temperature was raised from room temperature to 130°C over 2 hours at 200 RPM without nitrogen purging. It was maintained at 130°C for 3 hours, during which the white slurry became a clear solution. It was then raised to 240°C over 16 hours. Immediately upon reaching 240°C @ 300 RPM, 3.0 wt% of seed crystals (11.2 g, 100-mesh needle-like) were added, and the slurry was kept in this state. The reaction mixture was maintained at 240°C for 3 hours. The reaction mixture was then cooled to approximately 150°C and slowly and carefully poured into 2.8 L of water in a 4 L beaker at room temperature, while stirring at 250 RPM for 10 min. The white slurry was then filtered and dried under vacuum in the oven for 4 hours. The solids were then transferred to a beaker and stirred with 700 mL of water for 10 min, and dried under vacuum in the oven overnight. The crude yield was 87.6%. Further drying of the product in a 50°C oven overnight provided good sieve yields (76.7% @ 99 min; 99.2% @ 198 min).

[0139] Example 2: Preparation of methylpyrrolidone phosphonic acid

[0140] At room temperature, methylphosphonic acid (MPA) (1920 g, 15 equivalents, fresh aqueous solution, 75%) and Al₂O₃ (0.8 g, 7.5 mmol, based on a total MPA concentration of 0.05 mol%) were placed in a 2 L RBF container equipped with a magnetic stir bar. The solvent water was carefully removed by heating (reactor set to 200°C), followed by careful evacuation to remove water produced during the reaction. The target endpoint was 33% conversion.

[0141] After 1 hour, the reactor was set at 200°C, with vacuum starting at 19.4 Torr and ending at 14.2 Torr, achieving a conversion rate of 34.1%.

[0142] Example 3 - Aluminum in methylphosphonic acid solution

[0143] At room temperature, MPA (1024 g, 8 equivalents, fresh aqueous solution, 75%) and Al₂O₃ (50.2 g, total 0.50 mol, 1.0 equivalent, combined with the catalytic amount from Example 2) were mixed in a 3 L reactor. The reactor temperature was set to 130°C at 100 RPM without nitrogen purging. The reactor temperature stabilized at approximately 110°C for about 1 hour, during which the white slurry became opaque and then a clear, pale yellow solution. After the reactor temperature stabilized at 130°C, the reaction mixture was maintained at 130°C overnight. The next morning, a vacuum was carefully applied to remove water while the reactor temperature was set to 200°C, and finally the chamber vacuum stabilized at 57 Torr until no distillate was produced.

[0144] Example 4 - Flame retardant

[0145] The methyl pyrophosphonic acid product of Example 2 was preheated to 205°C and seed crystal material (1.9 g, 0.5 wt% of the theoretical amount of flame retardant) was added. The preheated methylphosphonic acid was then poured into the 200°C solution of Example 3 at 300 RPM. After mixing, the reaction was maintained at 200°C for 5 minutes. The reaction mixture was then cooled to 130°C and slowly and carefully poured into 2.8 L of water in a 4 L beaker at room temperature and stirred at 250 RPM for 10 minutes. The white slurry was filtered and dried under vacuum for 4 hours. The solid was then transferred to a beaker and stirred with 700 mL of water for 10 minutes and dried under vacuum overnight. The crude yield was 83.0%, and the yield on a 100-mesh sieve at 99 min was 94.0%.

[0146] The obtained material has an acid content of < 0.1 mg KOH / g sample and a P to Al ratio of 4:1 (ICP elemental analysis).

[0147] An image of the crystal obtained by scanning electron microscopy at x500 magnification is shown below. Figure 2 middle.

[0148] Particle size was determined using a Sympatec HELOS / KR RODOS laser diffraction sensor with a VIBRI / L dry dispersion plate. The particle size distribution of the material is... Figure 6 As shown in the image.

[0149] Example 5 - Flame Retardant

[0150] MPA (1553 g, 12 equivalents, 75% aqueous solution) was placed in a 3 L resin reactor. Careful heating was applied to remove water (reactor set to 200°C, 150 RPM), and a vacuum was carefully applied when no distillate was produced. The target endpoint for conversion was 71% (31P NMR measurement, MPA set to 100%). On day 2, with the reactor set at 200°C and a vacuum of 150 Torr, the conversion was 37.2%; on day 3, with the reactor set at 200°C and a vacuum of 200 Torr, the conversion was 54.4%; and on day 4, with the reactor set at 200°C and a vacuum of 120 Torr, the conversion to pyrophosphonic acid was 69.1%.

[0151]

[0152] MPA (768 g, 6 equivalents, fresh aqueous solution, 75%) and Al₂O₃ (51.0 g, 0.50 mol, 1.0 equivalent) were mixed separately at room temperature. The reactor temperature was initially set to 130°C at 250 RPM without nitrogen purging. The reactor temperature stabilized at approximately 110°C for about 1 hour, during which the white slurry became opaque, then a clear, pale yellow solution. The reactor temperature was then set to 200°C. A vacuum was carefully applied to remove water, and finally stabilized at 140 Torr until no more distillate was produced.

[0153]

[0154] Pyrophosphonic acid was preheated to 200°C and then mixed with Al in MPA solution at 200°C and 250 RPM. No seed material was used, and the slurry was retained. The reaction mixture was kept at 200°C for 3 hours. The reaction mixture was then slowly and carefully poured into 2.8 L of water in a 4 L beaker at room temperature and stirred at 250 RPM for 10 min. The white slurry was filtered off and dried under vacuum for 4 hours. The solid was then transferred to a beaker and stirred with 700 mL of water for 10 min and dried under vacuum overnight. The crude yield was 88.7%. SEM showed the product to be needle-like. The material was further dried in a 60°C oven and sieved through a 100-mesh sieve (67.5% @ 99 min; 97.2% @ 198 min).

[0155]

[0156] The particle size of the obtained material was determined using a Sympatec HELOS / KR RODOS laser diffraction sensor with a VIBRI / L dry dispersion plate. The particle size distribution of the material is as follows: Figure 7 As shown in the image.

[0157] Example 6 - Effect of precipitation temperature on crystal morphology

[0158] The method of Example 5 was repeated, but at different precipitation temperatures ranging from 130°C to 210°C. Images of the resulting crystalline products obtained using a HITCHI TM3030Plus Tabletop microscope at x500 are shown in [images]. Figure 3 middle.

[0159] The particle size of some of the obtained materials was determined using a Sympatec HELOS / KR RODOS laser diffraction sensor with a VIBRI / L dry dispersion plate.

[0160]

[0161] Example 7 - Aspect Ratio of Flame Retardant Materials

[0162] A. SEM Sample Preparation

[0163] Combine approximately 50 mg of flame retardant and 5 mg of cetyltributylammonium bromide in a 60 mL wide-mouth bottle. Dilute with 60 mL of hexane. Shake for 2 x 10 s and pipette 1-2 drops onto the SEM sample stage.

[0164] B. SEM Image Acquisition

[0165] Six images were collected at 100x magnification on a HITCHI TM3030Plus Tabletop microscope to avoid repeated measurements of the same crystal.

[0166] C. Result

[0167] Length, width and aspect ratio

[0168] Example 8 - Flame-retardant polymer composition

[0169] Polymer compositions were prepared and their flame retardancy was evaluated under UL-94 testing. The UL-94 V-0 rating was measured at a thickness of 0.8 mm for a polymer composition containing 14% by weight of the flame retardant of Example 6 and 10% by weight of melamine and 30% by weight of glass-filled polyamide 6,6.

[0170]

[0171] Example 9 - Preparation of pyrophosphonic acid

[0172] MPA (1920 g, 15 equivalents, 75% aqueous solution) was placed in a 2 L round-bottom flask equipped with a magnetic stir bar and carefully heated to remove the solvent water (the reaction vessel temperature was set to 200°C). Then, a vacuum was carefully applied to remove the water generated in the reaction. Three experiments were conducted; experiments 2 and 3 were loaded with a certain amount of Al2O3 as a catalyst for the formation of pyrophosphonic acid.

[0173] Experiment 1. Vacuum @ 9.31 Torr, conversion rate 40.5%, 1 day

[0174] Experiment 2. Vacuum @ 19.4 Torr, 0.05 mol% Al2O3, @ 1 h, conversion rate 34.1%.

[0175] Experiment 3. Vacuum @ 14.6 Torr, 0.5 mol% Al2O3, @ 1 h, conversion rate 34.8%

[0176] Example 10 - Preparation of pyrophosphonic acid

[0177] MPA (1920 g, 15 equivalents, 75% aqueous solution) was placed in a 2 L round-bottom flask equipped with a magnetic stir bar. Careful heating was applied to remove the solvent water (reactor set to 240°C). When the reactor temperature reached 240°C, N2 was purged through the subsurface diffuser at 5 L / min. The reactor temperature was temporarily lowered and then returned to 240°C. The reaction was started at 240°C, and aliquots were taken every 0.5 h until the end of the 5 h mark, and the conversion was measured using 31P NMR. The catalyst Al2O3 loadings are shown as follows: Series 1, 0 mol% catalyst; Series 2, 0.005 mol%; Series 3, 0.05 mol%; Series 4, 0.5 mol%.

[0178]

[0179] The conversion rate changes over time as follows: Figure 8 As shown.

[0180]

[0181] When the nitrogen flow rate was reduced to 2-4 L / min, a lower conversion rate was observed.

[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 the specification and practice of this disclosure, that various modifications and variations may be made without departing from the scope of the invention as claimed. Therefore, the specification and embodiments are intended to be exemplary only, and the true scope of the invention is indicated by the appended claims and their equivalents.

Claims

1. A method for producing a phosphorus-containing flame retardant, comprising: Preparation of metal phosphonic acid solution; and The reaction mixture of unsubstituted or alkyl or aryl substituted pyrophosphonic acid with the metal phosphonic acid solution at a reaction temperature of 130°C to 240°C is sufficient to produce the phosphorus-containing flame retardant.

2. The method of claim 1, further comprising the step of preparing the unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid by: A catalytic amount of catalyst is added to unsubstituted or alkyl- or aryl-substituted phosphonic acids, and Heating is carried out at a temperature of about 105°C or higher for a sufficient amount of time to produce unsubstituted or substituted pyrophosphonic acids.

3. The method of claim 2, wherein the temperature of the heating step is from about 130°C to about 290°C.

4. The method of claim 3, wherein the temperature of the heating step is about 180°C to 240°C.

5. The method according to claim 2, wherein the catalyst is a Lewis acid.

6. The method of claim 5, wherein the Lewis acid is selected from the group consisting of: iron halides (FeX) n Titanium halide (TiX) n Titanium alkoxide (Ti(OR)4), titanium dioxide (TiO2), aluminum halide (AlX3), aluminum alkoxide (Al(OR)3), tin halide (SnX) n Boron trihalides (BX3), magnesium halides (MgX2), calcium halides (CaX2), and zinc halides (ZnX2).

7. The method of claim 1, further comprising the step of preparing the unsubstituted or alkyl or aryl-substituted pyrophosphonic acid by heating the unsubstituted or alkyl or aryl-substituted phosphonic acid in the presence of nitrogen at a temperature in the range of 230°C to 250°C, preferably about 240°C, wherein nitrogen is provided at a flow rate of 4 L / min to 6 L / min, preferably about 5 L / min.

8. The method according to any one of claims 1-7, further comprising, prior to the step of reacting the reaction mixture, removing all or substantially all of any water generated during the preparation of the metal phosphonic acid solution and / or unsubstituted or substituted pyrophosphonic acid.

9. The method of claim 8, wherein the removal step includes using a vacuum.

10. The method according to any one of claims 1-9, wherein the reaction mixture is prepared at a preparation temperature below the reaction temperature.

11. The method of claim 10, wherein the preparation temperature is in the range of about 15°C to about 40°C.

12. The method according to any one of claims 1-11, wherein the reaction temperature is in the range of about 190°C to about 210°C.

13. The method of claim 12, wherein the reaction temperature is in the range of about 195°C to about 205°C.

14. The method according to any one of claims 1-13, wherein the metal phosphonic acid solution is prepared from a mixture of the following: (a) Unsubstituted or alkyl or arylphosphonic acids, (b) the solvent for the phosphonic acid, and (c) Metals capable of forming polycations, or those of formula M p (+)y X q The appropriate metal compound is represented by M, where M is a metal, (+)y represents the charge of the metal cation, y is 3, X is an anion, and the values ​​of p and q provide the charge balance of the metal compound.

15. The method of claim 14, wherein components (a) and (b) of the mixture are in solution form, and preparing the mixture comprises mixing component (c) with the solution.

16. The method according to claim 14, wherein the molar ratio of component (a) to component (c) in the reaction mixture is in the range of about 4:1 to about 50:

1.

17. The method of claim 14, wherein the solvent is selected from water, sulfone, sulfoxide, halogenated hydrocarbons, aromatic hydrocarbons, and ethers.

18. The method of claim 17, wherein the solvent comprises water.

19. The method of claim 14, wherein M is selected from Al, Ga, Sb, Fe, Co, B and Bi.

20. The method of claim 19, wherein M is Al.

21. The method of claim 14, wherein component (c) of the reaction mixture comprises a suitable metal compound, and said suitable metal compound is selected from metal oxides, halides, alkoxides, hydroxides, carbonates, carboxylates or phosphonates.

22. The method according to claim 21, wherein the suitable metal compound is selected from aluminum oxide, aluminum trichloride, aluminum hydroxide, aluminum isopropoxide, aluminum carbonate, aluminum acetate, iron(III) oxide, iron(III) chloride, iron(III) isopropoxide, and iron(III) acetate.

23. The method according to claim 14, wherein the unsubstituted or alkyl- or aryl-substituted phosphonic acid is represented by formula (I): (I)， Where R represents H and C. 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl or C 7-18 Aryl alkyl group, wherein the alkyl, aryl, alkylaryl, or aryl alkyl 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 Alkoxy carbonyl substitution.

24. The method of claim 23, wherein R is unsubstituted C. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Aryl alkyl group.

25. The method of claim 24, wherein R is unsubstituted C. 1-6 alkyl.

26. The method of claim 254, wherein R is methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl.

27. The method according to any one of claims 1-26, wherein the unsubstituted or alkyl or aryl substituted pyrophosphonic acid is free of or substantially free of water.

28. The method according to any one of claims 1-27, wherein the metal phosphonic acid solution is free of precipitates prior to the reaction step.

29. The method according to claim 1, further comprising the step of seeding the reaction mixture with a compound of empirical formula (III): (III) Where R is H, alkyl, aryl, alkylaryl, or arylalkyl; M is a metal and y is 3, such that M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation; a, b, and c represent the ratios of their corresponding portions relative to each other in the compound, and satisfy the charge balance equation 2(a) + c = b(y); and c is not zero.

30. The method according to any one of claims 1-29, wherein the unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid is represented by formula (II): (II), Where R represents H and C. 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl or C 7-18 Aryl alkyl group, wherein the alkyl, aryl, alkylaryl, or aryl alkyl 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 Alkoxy carbonyl substitution.

31. The method according to claim 30, wherein R in formula (II) is unsubstituted C. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl or C 7-10 Aryl alkyl group.

32. The method according to claim 30, wherein R in formula (II) is unsubstituted C. 1-6 alkyl.

33. The method according to claim 30, wherein R in formula (II) is methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl.

34. A phosphorus-containing flame retardant produced by the method according to any one of claims 1 to 26, wherein the phosphorus-containing flame retardant comprises a compound of empirical formula (III): (III), Where R is H, alkyl, aryl, alkylaryl, or arylalkyl; M is a metal and y is 3, such that M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation; a, b, and c represent the ratios of their corresponding portions relative to each other in the compound, and satisfy the charge balance equation 2(a) + c = b(y); and c is not zero. The phosphorus-containing flame retardant mentioned therein is a crystalline material with an Aspd90 of less than 10 as determined by a SEM imaging system.

35. The phosphorus-containing flame retardant according to claim 34, wherein M is Al, a is 1, b is 1, and c is 1.

36. A flame-retardant polymer composition comprising (i) a polymer and (ii) a phosphorus-containing flame retardant according to claim 34 or 35.

37. A flame-retardant material comprising a compound of empirical formula (III): (III), Where R is H, alkyl, aryl, alkylaryl, or arylalkyl; M is a metal and y is 3, such that M (+)y It is a metal cation, where (+)y represents the charge formally assigned to the cation; a, b, and c represent the ratios of their corresponding portions relative to each other in the compound, and satisfy the charge balance equation 2(a) + c = b(y); and c is not zero; Among them, phosphorus-containing flame retardants are crystalline materials with an aspect ratio (Aspd90) of less than 10, as determined by SEM imaging.

38. The flame retardant material according to claim 37, wherein M is Al, a is 1, b is 1, and c is 1.

39. The flame retardant material according to claim 37 or 38, wherein R is H or an alkyl group.

40. The flame-retardant material according to claim 39, wherein R is C 1-6 alkyl.

41. The flame retardant material according to claim 40, wherein R is methyl or ethyl.

42. A flame-retardant polymer composition comprising (i) a polymer and (ii) a flame-retardant material according to any one of claims 38 to 41.

Images