Flame-retardant polymer compositions without antimony trioxide

Abstract

The combination of one or more phosphorus-containing flame retardant compounds as described herein with at least one brominated flame retardant compound provides an effective flame retardant additive for thermoplastic polymers without the need for the use of antimony trioxide. Thus, flame-retardant thermoplastic compositions containing at least one thermoplastic polymer, at least one brominated flame retardant, and at least one phosphorus-containing flame retardant as described herein are provided. These compositions are useful in a wide range of applications, such as for electrical and electronic applications.

Description

[0001] This disclosure relates to flame retardant additives for use in thermoplastic compositions, and more specifically to combinations of flame retardant additives for use in thermoplastic polymers, including at least one brominated flame retardant and at least one phosphorus-containing flame retardant as described herein. Background Technology

[0002] Halogenated organic compounds, including oligomers and polymers, are widely used and are highly effective flame retardant additives for polymer resins. To meet the high flame retardancy standards for thermoplastics, these flame retardant systems are typically based on a combination of brominated flame retardants and antimony trioxide as a synergist. While antimony trioxide is an effective synergist, it tends to significantly increase smoke production, which can impair visibility and pose problems for safe evacuation in the event of a fire. Furthermore, antimony trioxide can negatively impact polymer properties in molded parts and is generally associated with increased costs. In addition, recent environmental standards have restricted the use of antimony trioxide in thermoplastic parts. Although there is a clear need for low-antimony trioxide or antimony trioxide-free flame-retardant plastics, this is generally...

[0003] A significantly increased loading of brominated flame retardant is required.

[0004] US Patent No. 9,475,933 discloses a flame-retardant thermoplastic composition that does not contain antimony trioxide, the composition comprising at least one brominated flame retardant and at least one metal phosphonate or metal hypophosphonate flame retardant having the following general formula:

[0005]

[0006] Where Me is a metal, and R... 1 and R 2 The compounds are the same or different straight-chain, branched, or cyclic alkyl groups having up to 6 carbon atoms, or benzyl groups, where n is a metal valence from 1 to 4, and x is 1 for metal phosphonates and 0 for metal hypophosphites. Methylaluminum methylphosphonate (AMMP) and aluminum diethylphosphite (DEPAL) are preferred and are cited as examples in this disclosure. However, the thermal stability of AMMP, as reported in U.S. Patent No. 8,889,773, may limit its use in thermoplastic polymers processed and / or used at high temperatures. Summary of the Invention

[0007] According to this disclosure, thermally stable phosphorus-containing flame retardants have been developed in combination with one or more brominated flame retardants, providing highly effective flame retardant additives for use in thermoplastic polymers without the need for antimony trioxide. Such flame-retardant thermoplastic compositions can be used in a wide range of applications, such as electrical and electronic applications. The phosphorus-containing flame retardants disclosed herein are also described in the applicant's co-pending patent applications PCT / US 2019 / 067184 and PCT / US 2019 / 067230, which provide the additional benefit of being compounded into thermoplastic polymers (such as high-temperature polyamides and polyterephthalates) at high temperatures without decomposition due to the high thermal stability of the phosphorus-containing flame retardants. Therefore, the additive compositions disclosed herein can be used in a wide range of thermoplastic applications, particularly in thermoplastic polymers processed and / or used at high temperatures.

[0008] This disclosure relates to an antimony trioxide-free flame-retardant thermoplastic composition comprising: (a) at least one thermoplastic polymer, (b) at least one brominated flame retardant, and (c) at least one phosphorus-containing flame retardant having empirical formula (I):

[0009]

[0010] Where R is H, alkyl, aryl, alkylaryl, or arylalkyl, 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 assigned to the cation, a, b and c represent the ratios of these components in the compound relative to each other, and satisfy the charge balance equation 2(a)+c=b(y), and c is not zero.

[0011] A method for preparing a flame-retardant thermoplastic composition is also disclosed, the method comprising blending (a) at least one thermoplastic polymer, (b) at least one brominated flame retardant, and (c) at least one phosphorus-containing flame retardant having the empirical formula (I) above.

[0012] The foregoing overview is not intended to limit the scope of the claimed invention in any way. Furthermore, it should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative and do not limit the scope of the claimed invention. Attached Figure Description

[0013] Figure 1 The results of thermogravimetric analysis (TGA) of an exemplary phosphorus-containing flame retardant material produced according to Example 1 of this disclosure are shown.

[0014] Figure 2 The results of thermogravimetric analysis (TGA) of an exemplary phosphorus-containing flame retardant material produced according to Example 7 of this disclosure are shown. Detailed Implementation

[0015] Unless otherwise specified, the term "a / an" in this application means "a / an or more than one / an".

[0016] Unless the context otherwise indicates, the term "alkyl" in this application includes "arylalkyl".

[0017] Unless the context otherwise indicates, the term "aryl" in this application includes "alkylaryl".

[0018] Unless the context otherwise indicates, the term "phosphonic acid" as used herein refers to unsubstituted or alkyl- or aryl-substituted phosphonic acids.

[0019] Unless the context otherwise indicates, the term “pyrophosphonic acid” as used herein refers to unsubstituted or alkyl- or aryl-substituted pyrophosphonic acids.

[0020] According to this disclosure, a combination of one or more phosphorus-containing flame retardant compounds as described herein with at least one brominated flame retardant compound provides a highly effective flame retardant additive for thermoplastic polymers without the need for the use of antimony trioxide.

[0021] At least one thermoplastic polymer may be a thermoplastic polyester, polyamide, polystyrene, including high-impact polystyrene (HIPS), polyolefin, polycarbonate, polyurethane, polyphenylene ether, or other thermoplastic polymers. In many embodiments, the thermoplastic polymer includes a polyester (e.g., polyalkylene terephthalate) or a polyamide. More than one thermoplastic polymer (thermoplastic polymer blend) may be used. The thermoplastic polymer may be unreinforced or reinforced, such as glass-reinforced, such as glass-filled polyester (e.g., glass-filled polyalkylene terephthalate) or glass-filled polyamide.

[0022] Examples of thermoplastic polyesters include homopolymers and copolyesters obtained by polycondensation of an acid component and a glycol component or by polycondensation of a hydroxycarboxylic acid and a lactone component. Suitable polyesters, for example, may be selected from polybutylene terephthalate and polyethylene terephthalate.

[0023] The diol component may contain one or more of the following diols: ethylene glycol, trimethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, hexamethylenediol, decanediol, cyclohexanediol, or neopentyl glycol. The acid component may contain one or more of the following acids: terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenoxyethylenedicarboxylic acid, p-hydroxybenzoic acid, sebacic acid, adipic acid, and derivatives thereof forming polyesters.

[0024] In many embodiments, the thermoplastic polyester is selected from polyethylene terephthalate, polypropylene terephthalate, polybutanediol terephthalate, and blends thereof. For example, a thermoplastic polyester blend may comprise from about 1 to about 99 parts by weight of one polyester and from about 99 to about 1 part by weight of a different polyester, based on a combination of two components in 100 parts by weight. Polybutanediol terephthalate may be obtained by polymerizing a diol component consisting of at least 70 mol%, for example, at least 80 mol% of 1,4-butanediol, with an acid component consisting of at least 70 mol%, for example, at least 80 mol% of terephthalic acid and / or its derivatives forming the polyester.

[0025] Thermoplastic polyamides include polyamides derived from diamines and dicarboxylic acids, polyamides obtained from aminocarboxylic acids (including combinations with diamines and / or dicarboxylic acids), and polyamides derived from lactams (including combinations with diamines and / or dicarboxylic acids). Suitable examples of polyamides include aliphatic polyamides such as polyamide-4,6, polyamide-6, polyamide-6,6, polyamide-6,10, polyamide-6,12, polyamide-11, and polyamide-12; polyamides obtained from aromatic dicarboxylic acids (such as terephthalic acid and / or isophthalic acid) and aliphatic diamines (such as hexamethylenediamine or nonadiamine); polyamides obtained from aliphatic dicarboxylic acids (such as adipic acid and / or azelaic acid) and aromatic diamines (such as m-phenylenediamine); polyamides obtained from aromatic and aliphatic dicarboxylic acids (such as terephthalic acid and adipic acid) and aliphatic diamines (such as hexamethylenediamine); polyamides obtained from adipic acid, azelaic acid, and 2,2-bis-(p-aminocyclohexyl)propane; and polyamides obtained from terephthalic acid and 4,4'-diaminodicyclohexylmethane. Mixtures and / or copolymers of two or more of the aforementioned polyamides or their prepolymers may also be used.

[0026] Polyamides can be prepared by any known method, such as by polymerization of a monoamino monocarboxylic acid or lactam thereof having at least two carbon atoms between an amino group and a carboxylic acid group, a diamine having at least two carbon atoms between an amino group and a dicarboxylic acid group in substantially equimolar proportions, or a monoamino carboxylic acid or lactam thereof as defined above, together with a diamine and a dicarboxylic acid in substantially equimolar proportions. The dicarboxylic acid can be used in the form of its functional derivatives, such as salts, esters, or acyl chlorides.

[0027] Polyamides with a melting point of at least 280°C are widely used in the production of molding compositions that enable the production of molded articles with excellent dimensional stability at high temperatures and very good flame retardant properties, for example, in the electrical and electronics industries. This type of molding composition is needed, for example, in the electronics industry to produce components mounted on printed circuit boards according to so-called surface mount technology (SMT). In this application, these components must withstand temperatures up to 270°C for short periods without dimensional changes.

[0028] These high-temperature polyamides include certain polyamides produced from alkyl diamines and diacids, such as polyamides 4 and 6. Furthermore, many high-temperature polyamides are aromatic and semi-aromatic polyamides, i.e., homopolymers, copolymers, terpolymers, or higher polymers derived from monomers containing aromatic groups. Aromatic or semi-aromatic polyamides can be used, or blends of aromatic and / or semi-aromatic polyamides can be used. Blends with aliphatic polyamides can also be used.

[0029] Examples of suitable high-temperature aromatic or semi-aromatic polyamides include polyamide-4,T, poly(m-adipoxymethyldimethyldiamine) (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 include: hexamethylene terephthalamide / 2-methylpentanediamine copolyamide (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 (polyamide-6,T / 6,I) copolymer; etc.

[0030] Therefore, certain embodiments of the present invention relate to compositions comprising polyamides that melt at high temperatures (e.g., 280°C or higher, 300°C or higher, or 320°C or higher). In some embodiments, the polyamides have a melting temperature from 280°C to 340°C, such as polyamides 4, 6, or the aforementioned aromatic and semi-aromatic polyamides.

[0031] Preferred polyamides are polyamide-6, polyamide-6,6, polyamide-11, polyamide-12, polyphthalamides such as polyamide-4,T, polyamide-6,T / 6,6 and polyamide-6,6 / 6,T / 6,I copolymers, glass-filled polyamides thereof, and blends thereof. For example, thermoplastic polyamide blends.

[0032] It may contain a combination of two components, ranging from about 1 to 99 parts by weight of one polyamide and from about 99 to about 1 part by weight of a different polyamide, based on a combination of 100 parts by weight.

[0033] In some embodiments, the polymer is a thermoplastic elastomer (e.g., a thermoplastic polyolefin or a thermoplastic polyurethane). In some embodiments, the thermoplastic elastomer is a thermoplastic polyurethane.

[0034] To reduce the molding shrinkage coefficient and linear expansion coefficient of the resulting molded articles and improve high and low thermal shock properties, at least one inorganic filler can be added to flame-retardant thermoplastic compositions. Depending on the desired article, various fillers in fibrous or non-fibrous form (e.g., powders, sheets) can be used. Some examples of inorganic filler types of fiber fillers include glass fibers, glass fibers with non-circular cross-sections (e.g., flat fibers), carbon fibers, silica fibers, silica-alumina fibers, zirconium oxide fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and other metallic fiber materials (e.g., stainless steel, aluminum, titanium, copper, and brass). Typical fiber fillers are glass fibers or carbon fibers. Alternatively, inorganic fillers can be powdered fillers, such as carbon black, graphite, silica, quartz powder, glass beads, glass powder, calcium silicate, kaolin, talc, clay, diatomaceous earth, silicates (such as wollastonite), metal oxides (such as iron oxide, titanium oxide, zinc oxide, and aluminum oxide), metal hydroxides, metal carbonates (such as calcium carbonate and magnesium carbonate), metal sulfates (such as calcium sulfate and barium sulfate), silicon carbide, silicon nitride, boron nitride, and various metal powders. Another example of inorganic fillers is sheet-like fillers, such as mica, glass flakes, and various metal foils. These inorganic fillers can be used alone or in combination of two or more. In use, it is desirable to pre-treat the inorganic fillers with a sizing agent or surface treatment agent, if necessary.

[0035] The amount of at least one inorganic filler in the flame-retardant thermoplastic composition that does not contain antimony trioxide can be from about 1 to about 50% by weight, for example from about 5 to about 50% by weight, from about 10 to about 40% by weight, or from about 15 to 30% by weight, based on the total weight of the flame-retardant thermoplastic composition.

[0036] Other components typically used in amounts less than 10% by weight, such as less than 5% by weight, of the flame-retardant thermoplastic composition include, but are not limited to, antioxidants, UV stabilizers, lubricants, impact modifiers, acid scavengers, heat stabilizers, pigments, dyes, optical brighteners, antistatic agents, anti-dripping agents, and other additives for enhancing resin properties. Typically, transesterification inhibitors are used in amounts from 0.01% to 0.5% by weight and include zinc dihydrogen phosphate, zinc phosphate, or other types of inhibitors. Conventional stabilizer additives are typically used in amounts from 0.01% to 5% by weight of the total flame-retardant thermoplastic composition and include, for example, hindered phenols and antioxidants. Typical anti-dripping agents include tetrafluoroethylene polymers.

[0037] At least one brominated flame retardant and at least one phosphorus-containing flame retardant are present in the flame-retardant thermoplastic composition in an effective amount of flame retardant.

[0038] In many embodiments, the antimony trioxide-free flame-retardant thermoplastic composition comprises at least one thermoplastic polymer (a) in an amount from about 30 to about 95% by weight, at least one brominated flame retardant (b) in an amount from about 3 to about 30% by weight, and at least one phosphorus-containing flame retardant (c) in an amount from about 1 to about 10% by weight, all weight percentages based on the total weight of the flame-retardant thermoplastic composition. In further embodiments, the antimony trioxide-free flame-retardant thermoplastic composition comprises at least one thermoplastic polymer (a) in an amount from about 30 to about 90% by weight, at least one brominated flame retardant (b) in an amount from about 5 to about 30% by weight, and at least one phosphorus-containing flame retardant (c) in an amount from about 1 to about 10% by weight, all weight percentages based on the total weight of the flame-retardant thermoplastic composition. In some embodiments, the flame-retardant thermoplastic composition further comprises at least one inorganic filler in an amount from about 1 to about 50% by weight based on the total weight of the flame-retardant thermoplastic composition. Typically, at least one inorganic filler is present from about 5 to about 50% by weight, for example from about 10 to about 40% by weight, or from about 15 to about 30% by weight, based on the total weight of the flame-retardant thermoplastic composition.

[0039] Non-limiting examples of suitable brominated flame retardant compounds include decabromodiphenyl ether, decabromodiphenyl ethane, tetrabromobisphenol A, tetrabromobisphenol A bis(2,3-dibromopropyl ether), tris(tribromophenoxy)triazine, tris(tribromoneopentyl)phosphate, brominated polyacrylate, brominated polystyrene, polybromostyrene, poly(dibromophenyl ether), brominated styrene-butadiene-styrene copolymer, brominated epoxy polymer, end-capped brominated epoxy polymer, phenoxy-terminated carbonate oligomers of tetrabromobisphenol A, tetradecylbromodiphenoxybenzene, ethylene bis(tetrabromophthalimide), tetrabromobisphenol S bis(2,3-dibromopropyl ether), 2-ethylhexyltetrabromophthalate, and bis(tribromophenoxy)ethane:

[0040] Decabromodiphenyl ether

[0041]

[0042] Decabromodiphenyl ethane (such as that sold under the trade name Firemaster 2100R)

[0043]

[0044] Tetrabromobisphenol A (such as that sold under the trade name BA-59P)

[0045]

[0046] Tetrabromobisphenol A bis(2,3-dibromopropyl ether)

[0047]

[0048] Tris(tribromophenoxy)triazine

[0049]

[0050] Tris(tribromonepentyl) phosphate

[0051] Brominated polyacrylate

[0052] Brominated polystyrene

[0053]

[0054] Polybrominated styrene (such as that sold under the trade names PDBS-80 and Firemaster PBS-64HW)

[0055]

[0056] Poly(dibromophenyl ether) (such as those sold under the trade name Uniplex FRP-64)

[0057]

[0058] Brominated styrene-butadiene polymers (such as those marketed under the trade name Emerald) (3000 sold)

[0059]

[0060] Brominated epoxy polymers

[0061]

[0062] End-capped brominated epoxy polymers

[0063]

[0064] Phenoxy-terminated carbonate oligomers of tetrabromobisphenol A (such as those sold under the trade names BC-25 and BC-58)

[0065]

[0066] Tetradecanodiphenoxybenzene

[0067]

[0068] Ethylenebistetrabromophthalimide

[0069]

[0070] Tetrabromobisphenol S-bis(2,3-dibromopropyl ether)

[0071]

[0072] 2-Ethylhexyltetrabromophthalate (such as those sold under the trade names Uniplex FRP45 and Firemaster BZ-54)

[0073]

[0074] bis(tribromophenoxy)ethane

[0075]

[0076] At least one phosphorus-containing flame retardant disclosed herein has the following empirical formula:

[0077]

[0078] Where R is H, alkyl, aryl, alkylaryl, or arylalkyl, M is a metal and y is 2 or 3, such that M (+)y The product is a metal cation, where (+)y represents the charge formally assigned to the cation, a, b, and c represent the ratios of these components in the compound relative to each other, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero. Typically, a is 0, 1, or 2 (e.g., 0 or 1), b is from 1 to 4 (e.g., 1 or 2), and c is 1 or 2, and the product is charge balanced. Examples of suitable metals (M) include, but are not limited to, Al, Ga, Sb, Fe, Co, B, Bi, Mg, Ca, and Zn.

[0079] Similar to inorganic coordination compounds, formula (I) is empirical or idealized, allowing these compounds to be coordination polymers, complex salts, salts sharing certain valence atoms, etc. For example, in many embodiments, empirical formula (I) represents the monomer unit (i.e., coordination entity) of a coordination polymer, and the extended coordination polymer structure thereby forms the phosphorus-containing flame retardant disclosed herein.

[0080] In some embodiments, y in equation (I) is 2 (i.e., M (+)y (where M is a divalent cationic metal), a is 0, b is 1, and c is 2. In some embodiments, the divalent cationic metal M is Mg, Ca, or Zn. In other embodiments, in formula (I), y is 3 (i.e., M is a divalent cationic metal), a is 0, b is 1, and c is 2. (+)y (where M is a trivalent cationic metal), a is 1, b is 1, and c is 1. In some embodiments, the trivalent cationic metal M is selected from Al, Ga, Sb, Fe, Co, B, and Bi. In some embodiments, the trivalent cationic metal M is Al, Fe, Ga, Sb, or B.

[0081] In one instance, M is Al and y is 3, and the phosphorus-containing flame retardant has the following empirical formula:

[0082]

[0083] As shown herein, the absence of subscripts a, b, and c in the empirical formula indicates that each subscript is 1, signifying a ratio of 1:1:1 for the dianionic pyrophosphonic acid ligand, the metal atom, and the monoanionic pyrophosphonic acid ligand. In many embodiments, empirical formula (II) represents the repeating monomer unit (i.e., the coordination entity) of the coordination polymer, thereby extending the coordination polymer structure to form the phosphorus-containing flame retardant disclosed herein.

[0084] Typically, R represents H and C. 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl, or C 7-18 Arylalkyl, wherein the alkyl, aryl, alkylaryl, or arylalkyl group is unsubstituted or converted by halogen, hydroxyl, amino, C 1-4 Alkylamino, di-C 1-4 Alkylamino, C 1-4 Alkoxy, carboxyl or C 2-5 Alkoxycarbonyl substitution. In some embodiments, the alkyl, aryl, alkylaryl, or arylalkyl group is an unsubstituted C10 group. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl, or C 7-10 Arylalkyl, for example, C 1-6 Alkyl, phenyl, or C 7-9 Alkyl aryl. In some embodiments, R is a substituted or unsubstituted C. 1-6Alkyl, C6 aryl, C 7-10 alkylaryl, or C 7-12 Arylalkyl, for example, C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl, or C 7-10 Arylalkyl. In many embodiments, R is an unsubstituted C. 1-12 Alkyl, for example, C 1-6 Alkyl groups. In many embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0085] R, as an alkyl group, can be a straight-chain or branched alkyl group having a specific number of carbons, and includes, for example, unbranched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl, and 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.

[0086] 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 alkyl groups selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, etc. Examples of R as arylalkyl include, for example, benzyl, phenethyl, styryl, cumyl, phenylpropyl, etc.

[0087] In many embodiments, R is selected from methyl, ethyl, propyl, isopropyl, butyl, phenyl, and benzyl. In some embodiments, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al, Fe, Zn, or Ca.

[0088] The phosphorus-containing flame retardant disclosed herein may be a mixture of compounds having empirical formula (I).

[0089] Compared to phosphorus-containing flame retardants described in the art, the phosphorus-containing flame retardants disclosed herein have a higher phosphorus content (i.e., a higher ratio of phosphorus atoms to metal atoms (P to M)). For example, trivalent cationic metals (e.g., aluminum) and divalent cationic metals (e.g., zinc) are known to form trisubstituted and disubstituted charge-balanced compounds, respectively. As seen in the art, aluminum triphosphonates—having a phosphorus-aluminum ratio of 3:1—and zinc diphosphonates—having a phosphorus-zinc ratio of 2:1—are known as flame retardants. However, according to the pyrophosphonic acid ligand formation disclosed herein, the phosphorus-to-metal ratio in the flame-retardant product is even higher. For example, as shown in the examples disclosed herein, the phosphorus-to-aluminum ratio, or the phosphorus-to-iron ratio, in the resulting flame-retardant product is 4:1.

[0090] Phosphorus-containing flame retardants with empirical formula (I) can be prepared by a method referred to herein as the solvent method or by a method referred to herein as the melt state method.

[0091] Phosphorus-containing flame retardants prepared by solvent method

[0092] Phosphorus-containing flame retardants of empirical formula (I) can be prepared by reacting a metal or a suitable metal compound with an unsubstituted or alkyl- or aryl-substituted phosphonic acid. The method comprises (i) preparing a reaction mixture containing (a) an unsubstituted or alkyl- or aryl-substituted phosphonic acid, (b) a solvent for the phosphonic acid, and (c) a metal or a suitable metal compound; and (ii) heating the reaction mixture at a reaction temperature of 105°C or higher or reacting for a sufficient amount of time to produce the phosphorus-containing flame retardant. In the reaction, the metal is oxidized and can be produced in its corresponding cation form by reaction with formula M. (+)y Let M be a metal, (+)y represent the charge of the metal cation, and y be 2 or 3. Suitable metal compounds can be derived from formula... X q The expression is represented by M, where M is a metal, (+)y represents the charge of the metal cation (y is 2 or 3), X is an anion, and the values ​​of p and q provide the charge balance of the metal compound.

[0093] In another embodiment, the phosphorus-containing flame retardant can be prepared by reacting a metal or suitable metal compound with an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid. The method includes (i) preparing a reaction mixture comprising (a) an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid, (b) a solvent for the pyrophosphonic acid, and (c) the metal or suitable metal compound as described above; and (ii) heating the reaction mixture at a reaction temperature of 20°C or higher or reacting for a time sufficient to produce the phosphorus-containing flame retardant.

[0094] As the resulting phosphorus-containing flame retardant product precipitates from the reaction mixture, the reaction product typically forms a slurry. Residual phosphonic acid, pyrophosphonic acid, and / or solvent after the reaction can be removed along with any possible byproducts by filtration and / or washing (e.g., with water). In many embodiments, substantially pure flame retardant materials are produced, such as flame retardants comprising a single compound or a mixture of substantially active compounds. The conversion based on the metal or metal compound is typically high, and the product can be readily separated and optionally further purified if desired.

[0095] Typically, the molar ratio of phosphonic acid or pyrophosphonic acid to a metal or suitable metal compound in the reaction mixture is greater than 2:1, such as about 3:1 or higher, about 4:1 or higher, about 5:1 or higher, about 6:1 or higher, about 7:1 or higher, or about 8:1 or higher. A larger molar excess of phosphonic acid or pyrophosphonic acid relative to the metal or suitable metal compound is commonly used in the reaction mixture, such as about 10:1 or higher, about 15:1 or higher, about 20:1 or higher, about 25:1 or higher, about 30:1 or higher, or any range therebetween. Large molar excesses of phosphonic acid or pyrophosphonic acid relative to the metal or suitable metal compound can be used. For example, molar ratios can be as high as about 50:1, up to about 100:1, up to about 300:1, up to about 500:1, or any range therebetween. However, as will be understood, at certain large molar excesses, process efficiency may be affected; for example, precipitation of the product from the reaction mixture may be hindered. In many embodiments, the molar ratio ranges from about 4:1, from about 5:1, from about 6:1, from about 8:1 or from about 10:1 to about 100:1 or to about 50:1, such as from about 8:1, from about 12:1, from about 16:1 or from about 20:1 to about 50:1 or to about 40:1.

[0096] The amount of time required to heat the reaction mixture at the reaction temperature sufficient to produce the flame retardant product. As used herein, the step of “heating the reaction mixture at the reaction temperature sufficient to produce the phosphorus-containing flame retardant” includes, but is not limited to, the following examples: during the process of heating the reaction mixture to the reaction temperature or heating the reaction mixture at the reaction temperature, all or substantially all of the components (b) of the reaction mixture—i.e., the solvent used for phosphonic acid or pyrophosphonic acid—evaporate from the reaction mixture. Therefore, it should be understood that even if all or substantially all of the solvent component (b) evaporates during the process of heating the reaction mixture to the reaction temperature or heating the reaction mixture at the reaction temperature, the term “reaction mixture” as used herein is still referred to as being heated at the reaction temperature.

[0097] The reaction temperature for producing the phosphorus-containing flame retardant of this disclosure according to the solvent method should be selected to promote the formation of pyrophosphonic acid ligands in the reaction products. For phosphonic acids, a reaction temperature of 105°C or higher is used. Without being bound by any particular theory, the reaction temperature is selected to produce the pyrophosphonic acid ligands via one or more dehydration reactions. In many embodiments, the metal or suitable metal compound and the 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 therebetween. The reaction temperature can be higher than those temperatures, 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 reaction 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 140°C to about 260°C. Water is formed through one or more dehydration reactions, which may potentially lead to undesirable reverse (hydrolysis) reactions. Therefore, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction mixture, such as continuous water removal. For example, the reaction temperature may be selected above the boiling point of water to the extent necessary to evaporate at least a portion or a desired amount (e.g., most, substantially all, or all) of the water from the reaction. Additional means, such as gas purging, vacuum, and / or other known means, may be used to facilitate the removal of water from the reaction system.

[0098] For pyrophosphonic acid, a reaction temperature of 20°C or higher is used. Since dehydration is unnecessary for pyrophosphonic acid, the reaction temperature can be lower than the reaction temperature of the aforementioned phosphonic acids. In many embodiments, the metal or suitable metal compound and pyrophosphonic acid react at temperatures above 20°C, such as about 40°C or higher, about 60°C or higher, about 80°C or higher, about 100°C or higher, about 140°C or higher, about 180°C or higher, about 200°C or higher, or any range therebetween. The reaction temperature can be higher than those mentioned above, such as up to about 300°C, up to about 400°C, or higher, but it typically does not reach or exceed the boiling point of pyrophosphonic acid. In many embodiments, the reaction temperature range is from about 25°C to about 350°C, from about 25°C to about 280°C, from about 30°C to about 260°C, from about 40°C to about 260°C, or from about 60°C to about 240°C. Depending on, for example, the metal compound used to react with pyrophosphonic acid, the reaction may produce water. As described above, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction, such as continuous water removal. For example, the reaction temperature may be selected above the boiling point of water to the extent necessary to evaporate at least a portion or a desired amount (e.g., most, substantially all, or all) of the water from the reaction. Additional means, such as gas purging, vacuum, and / or other known means, may be used to facilitate the removal of water from the reaction system.

[0099] The reaction can, but does not have to, be carried out under reduced pressure or vacuum.

[0100] In some embodiments of the solvent method, the solvent is a protic solvent (e.g., water), and the reaction system is designed to facilitate the removal of the protic solvent during heating of the reaction mixture, such as continuous removal. For example, a reaction temperature equal to or higher than the boiling point of the protic solvent can be selected to the extent necessary to evaporate at least a portion or a desired amount (e.g., most, substantially all, or all) of the protic solvent during heating of the reaction mixture. In some embodiments, the solvent is water, and the reaction temperature is about 110°C or higher, about 115°C or higher, about 120°C or higher, about 130°C or higher, about 140°C or higher, about 150°C or higher, or about 160°C or higher, as exemplified above. As further described herein, a reaction temperature equal to or higher than the melting point of phosphonic acid or pyrophosphonic acid can also be selected.

[0101] Typically, the flame retardant product will precipitate from the reaction mixture, allowing sufficient time for the reaction to proceed to achieve this precipitation. Generally, the amount of time required to achieve at least substantially conversion to the flame retardant product will depend on the reaction temperature, with higher temperatures generally resulting in shorter reaction times, depending on the metal or suitable metal compound in the reaction mixture. Typically, heating or the reaction occurs at the reaction temperature for a duration ranging from about 0.1 to about 48 hours, such as from about 0.2 to about 36 hours, from about 0.5 to about 30 hours, from about 1 hour to about 24 hours, such as from about 1 hour to about 12 hours, from about 1 hour to about 8 hours, or from about 1 hour to about 5 hours, although other durations may be used.

[0102] The reaction mixture can be prepared in any manner suitable for combining or mixing (a) an unsubstituted or alkyl or aryl-substituted phosphonic acid or pyrophosphonic acid, (b) a solvent for the phosphonic acid or pyrophosphonic acid, and (c) a metal or suitable metal compound. For example, these components can be combined simultaneously or at different times. In some embodiments, a metal or suitable metal compound (c) is added to a mixture of phosphonic acid or pyrophosphonic acid (a) and solvent (b), such as a solution. The metal or suitable metal compound (c) can be added to the reaction mixture once or in batches. Similarly, a mixture of phosphonic acid or pyrophosphonic acid (a), solvent (b), or phosphonic acid or pyrophosphonic acid (a) and solvent (b), such as a solution, can be added to the reaction mixture once or in batches.

[0103] In preparing the reaction mixture, phosphonic acid or pyrophosphonic acid (a), a solvent (b), and a metal or suitable metal compound (c) can be combined at a preparation temperature below the reaction temperature. The reaction mixture is then heated to the reaction temperature. For example, the preparation temperature can be chosen to promote the dissolution of phosphonic acid or pyrophosphonic acid (a) in the solvent (b), or otherwise to form a homogeneous liquid or solution of phosphonic acid or pyrophosphonic acid (a) and the solvent (b). At the preparation temperature, and depending on the metal compound (c), the reaction mixture can form a solution, suspension, or slurry, such as a homogeneous or substantially homogeneous suspension or slurry. In some embodiments, such as at higher preparation temperatures, the reaction mixture can form a solution. Typically, the reaction mixture will exist as a solution at or near the reaction temperature. In many embodiments, the preparation temperature is about 0°C or higher, but typically below 150°C, such as below 125°C, below 115°C, below 100°C, below 85°C, or below 65°C. For example, the preparation temperature can range from about 0°C to about 65°C or from about 15°C to about 40°C. In some embodiments, the reaction mixture is prepared at room temperature (e.g., from about 15°C to about 25°C). In some embodiments, the solvent (b) is preheated to the preparation temperature and combined with phosphonic acid or pyrophosphonic acid (a) and a metal or suitable metal compound (c). In some embodiments, the mixture of solvent (b) and phosphonic acid or pyrophosphonic acid (a) is preheated to the preparation temperature and combined with a metal or suitable metal compound (c).

[0104] Alternatively, the reaction mixture can be prepared at the reaction temperature. That is, the reaction mixture is prepared by combining (a) phosphonic acid or pyrophosphonic acid, (b) a solvent for the phosphonic acid or pyrophosphonic acid, and (c) a metal or suitable metal compound at the reaction temperature. For example, in some embodiments, preparing the reaction mixture involves preheating a mixture of solvent (b) and phosphonic acid or pyrophosphonic acid (a) to the reaction temperature and combining it with a metal or suitable metal compound (c).

[0105] In some embodiments, where the reaction temperature is above the melting temperature of phosphonic acid or pyrophosphonic acid, and after achieving the desired conversion to the flame retardant product (e.g., complete or substantially complete conversion), residual phosphonic acid or pyrophosphonic acid is present in the product reaction mixture. The product reaction mixture is cooled to a temperature above or not below the melting temperature of the residual phosphonic acid or pyrophosphonic acid to ensure that the phosphonic acid or pyrophosphonic acid remains in liquid form. This may be particularly useful in embodiments where a perceptible amount of solvent for the phosphonic acid or pyrophosphonic acid (i.e., component (b)) evaporates due to heating, making the remaining excess phosphonic acid or pyrophosphonic acid more likely to emerge from the solution. Excess phosphonic acid or pyrophosphonic acid and solvent (if present in the product reaction mixture) can be removed by filtration / washing and optionally recovered. The recovered excess phosphonic acid or pyrophosphonic acid and / or solvent can be recycled, for example, returned to a reactor in which a metal or suitable metal compound (c) reacts with the phosphonic acid or pyrophosphonic acid (a). After conversion to the reaction product, a solvent for phosphonic acid or pyrophosphonic acid (which may but must be the same as solvent component (b)) may be optionally added to dissolve or otherwise help remove excess phosphonic acid or pyrophosphonic acid. The phosphorus-containing flame retardant product is typically separated by filtration, optionally followed by additional processing (e.g., washing, drying, sieving, etc.). The resulting phosphorus-containing flame retardant product, typically in powder or granular form, is readily processable, i.e., requiring little or no grinding, milling, or other such physical processing before use. It should be understood that “direct” production of the phosphorus-containing flame retardant product in powder or granular form allows for post-processing of the reaction product, such as separation of the flame retardant product (e.g., separation of the flame retardant product from the remaining solvent), which may include processing the reaction product, for example, by filtration, sieving, washing, drying, etc.

[0106] The solvent used for phosphonic acid or pyrophosphonic acid can be any solvent capable of dissolving the phosphonic acid or pyrophosphonic acid component. This solvent should be inert or substantially inert to the reaction between the phosphonic acid or pyrophosphonic acid and a metal or suitable metal compound, and can be further selected taking into account 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 can be a combination of solvents used for phosphonic acid or pyrophosphonic acid. Typically, the phosphonic acid or pyrophosphonic acid is substantially or completely dissolved in the solvent. For example, the phosphonic acid or pyrophosphonic acid and the solvent can form a solution. In some embodiments, the phosphonic acid or pyrophosphonic acid can be partially dissolved and partially suspended or dispersed in the solvent. The type of solvent, the amount of solvent relative to the phosphonic acid or pyrophosphonic acid, and the mixing conditions can be selected to achieve a desired level of phosphonic acid dissolution, such as obtaining a high concentration of phosphonic acid or pyrophosphonic acid in the mixture while maintaining the phosphonic acid or pyrophosphonic acid in solution. Typically, the acid-to-solvent ratio ranges from about 10:1 to 1:10, about 5:1 to 1:5, or about 3:1 to 1:3 by weight. In some embodiments where the acid is partially dissolved and partially suspended or dispersed in a solvent, the preparation temperature or reaction temperature may be selected to be equal to or higher than the melting temperature of the acid to liquefy the acid suspended or dispersed in the solvent.

[0107] As described above, depending on the reaction temperature and the boiling temperature of the solvent used for phosphonic acid or pyrophosphonic acid, at least a portion of the solvent may evaporate from the reaction mixture when heated to or at the reaction temperature. In some embodiments, all, substantially all, or at least most of the solvent evaporates from the reaction mixture during heating. The solvent may be a high-boiling point (e.g., sulfolane or dimethyl sulfoxide (DMSO)) or a low-boiling point (e.g., chloroform or tetrahydrofuran (THF)). For example, in some embodiments, the solvent boils at a temperature equal to or below the reaction temperature, such that at least a portion of the solvent evaporates during heating of the reaction mixture, e.g., all, substantially all, or most of the solvent evaporates. The reaction temperature may be selected to be equal to or above the melting temperature of phosphonic acid or pyrophosphonic acid to ensure that the phosphonic acid or pyrophosphonic acid remains in liquid form when the solvent evaporates. In this way, using a large excess of phosphonic acid or pyrophosphonic acid in the reaction mixture allows the phosphonic acid or pyrophosphonic acid to act as both a reactant and a solvent in the reaction.

[0108] In other embodiments, the solvent has a boiling temperature above the reaction temperature to ensure it remains in the product reaction mixture, from which the flame retardant product of the reaction can be separated, as described herein. In some embodiments, the reaction temperature is selected to be below the melting temperature of phosphonic acid or pyrophosphonic acid.

[0109] Suitable solvents can be organic or inorganic. Examples of suitable solvents for phosphonic acids or pyrophosphonic acids include, but are not limited to, water, sulfones, sulfoxides, halogenated (e.g., chlorinated) hydrocarbons, aromatic hydrocarbons, and ethers. For example, in some embodiments, the solvent may be selected from water, sulfolane, dimethyl sulfone, tetrahydrofuran (THF), dimethoxyethane (DME), 1,4-dioxane, dimethyl sulfoxide (DMSO), 1,2-dichlorobenzene, chloroform, carbon tetrachloride, xylene, and mesitylene. In some embodiments, the solvent comprises water. In some embodiments, the solvent comprises an aqueous solution. In some embodiments, the reaction mixture is an aqueous reaction mixture.

[0110] The solvent can be proton or aproton. In many embodiments, the solvent used for pyrophosphonic acid is an aprotic solvent.

[0111] In some embodiments, solvent (b) comprises a sulfone having the formula R1R2SO2, wherein R1 and R2 are independently selected from C 1-6 Hydrocarbon groups, such as C 1-3 A hydrocarbon group, or R1 and R2 together with S to form a ring with 2, 3, 4, or 5 carbon atoms, which can be unsubstituted or C. 1-3 Alkyl-substituted. In some embodiments, R1 and R2 together with S form a di-, tri-, tetra-, or penta-methylene ring. In some embodiments, R1 and R2 are independently selected from C. 1-6 Alkyl group. In some embodiments, R1 or R2 is C2. 1-6 Alkyl and another is C 1-3 Alkyl group. In some embodiments, R1 and R2 are independently selected from C1 and C2. 1-3 Alkyl group. The alkyl group can be branched or linear. In some embodiments, R1 and R2 are both methyl, both ethyl, or both propyl. In other embodiments, R1 or R2 is methyl and the other is ethyl or propyl. In other embodiments, R1 or R2 is ethyl and the other is propyl. In some embodiments, the sulfone is sulfolane.

[0112] Phosonic acid can be represented by the following formula:

[0113]

[0114] Wherein R is H, alkyl, aryl, alkylaryl, or arylalkyl. In many embodiments, R is H, C 1-12 Alkyl, C 6-10 Aryl, C 7-18 alkylaryl, or C 7-18 Arylalkyl, wherein the alkyl, aryl, alkylaryl, or arylalkyl group is unsubstituted or converted by halogen, hydroxyl, amino, C 1-4 Alkylamino, di-C 1-4 Alkylamino, C 1-4Alkoxy, carboxyl or C 2-5 Alkoxycarbonyl substitution. In some embodiments, the alkyl, aryl, alkylaryl, or arylalkyl group is an unsubstituted C10 group. 1-12 Alkyl, C6 aryl, C 7-10 alkylaryl, or C 7-10 Arylalkyl, for example, 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 Arylalkyl, for example, C 1-4 Alkyl, C6 aryl, C 7-9 alkylaryl, or C 7-10 Arylalkyl. In many embodiments, R is an unsubstituted C. 1-12 Alkyl, for example, C 1-6 Alkyl groups. In many embodiments, lower alkyl phosphonic acids are used, such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, tert-butyl-, etc.

[0115] Pyrophosphonic acid can be represented by the following formula:

[0116]

[0117] Where R is as described above.

[0118] Methods for preparing phosphorus-containing flame retardants may use more than one phosphonic acid, more than one pyrophosphonic acid, or a combination of phosphonic acid and pyrophosphonic acid. In some embodiments, the phosphonic acid or pyrophosphonic acid is generated in situ. For example, preparing the reaction mixture may include preparing the phosphonic acid or pyrophosphonic acid, such as by hydrolyzing higher oligomeric phosphonic acids and / or cyclic phosphonic anhydride starting materials.

[0119] As used in this article, "suitable metal compound" refers to a compound having the following formula: X q The compound, wherein M is a metal that forms a 2+ or 3+ cation, and X is any anion of a compound 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. Values ​​of p and q provide charge-balanced metal compounds, such as aluminum oxide and Al₂O₃. In some embodiments, as described herein, unsubstituted metal M is used. Examples of suitable metals (M) include, but are not limited to, Al, Ga, Sb, Fe, Co, B, Bi, Mg, Ca, and Zn. In some embodiments, M is selected from Al, Fe, Mg, Zn, and Ca.

[0120] 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., of Al, Fe, Mg, Zn or Ca oxides, hydroxides, halides or alkoxides.

[0121] 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.

[0122] In some embodiments, a suitable metal compound is a metal phosphonate. As described herein, the metal in a metal phosphonate may be metal M. In some embodiments, the metal phosphonate is prepared by reacting an initial metal compound and a phosphonic acid with a solvent (e.g., water) for the phosphonic acid. The initial metal compound may be a compound of a suitable metal compound as described herein. In some embodiments, the initial metal compound and the phosphonic acid are reacted at room temperature or about room temperature, or at a temperature ranging from about 0°C to about 20°C. The resulting metal phosphonate can then be used as a suitable metal compound. For example, the phosphonic acid (e.g., one or more alkylphosphonic acids as described above) and the solvent (e.g., water) can be stirred to form a homogeneous solution. The solution can be cooled, for example, from about 0°C to about 20°C, and an initial metal compound (e.g., a metal oxide, halide, alkoxide, or hydroxide) can be added to react with the phosphonic acid. A metal phosphonate is formed and then used as a suitable metal compound for preparing phosphorus-containing flame retardants.

[0123] This preparation method can produce a mixture of phosphorus-containing flame retardant compounds, but in many embodiments, the method produces a phosphorus-containing flame retardant product as one or primarily a compound with a high conversion rate based on a metal or metal compound, such as at least 70%, 80%, 85%, 90%, 95%, 98% or higher, or any range thereof, in contrast to mixtures of compounds obtained by prior art methods involving heat treatment of metal phosphonates, as disclosed in U.S. Patent No. 9,745,449.

[0124] The reaction according to the solvent method usually proceeds as follows:

[0125]

[0126] Where M is a metal and y is 2 or 3, such that M (+)y M is a metal cation, where (+)y represents the charge of the cation; 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-balanced metal compound; R is H, alkyl, aryl, alkylaryl, or arylalkyl (as described herein); a, b, and c represent the ratios of their corresponding components relative to each other in the reaction product, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero. Typically, a is 0, 1, or 2 (e.g., 0 or 1), b is from 1 to 4 (e.g., 1 or 2), and c is 1 or 2, and the compound is charge-balanced. In some embodiments, as shown herein, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al, Fe, Zn, or Ca. In further embodiments, X is oxygen, hydroxyl, alkoxy, or halogen.

[0127] The general reaction scheme with pyrophosphonic acid can be represented as follows:

[0128] R, M, X, p, q, y, a, b, and c are as described above.

[0129] As discussed above, similar to inorganic coordination compounds, the formula of the reaction product is empirical or idealized, allowing the product to be a coordination polymer, a complex salt, a salt sharing certain valence atoms, etc. In many embodiments, the above-described reaction product represents a monomer unit (i.e., a coordination entity) of a coordination polymer, and the extended coordination polymer structure thereby forms the phosphorus-containing flame retardant disclosed herein.

[0130] In some embodiments, y is 2 (i.e., M). (+)y (where M is a divalent cationic metal), a is 0, b is 1, and c is 2. In some embodiments, the divalent cationic metal M is Mg, Ca, or Zn. In other embodiments, y is 3 (i.e., M is a divalent cationic metal). (+)yM is a trivalent cationic metal, where a is 1, b is 1, and c is 1. In some embodiments, the trivalent cationic metal M is selected from Al, Ga, Sb, Fe, Co, B, and Bi. In some embodiments, the trivalent cationic metal M is Al, Fe, Ga, Sb, or B. 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)).

[0131] In one instance, a phosphorus-containing flame retardant compound with the following empirical formula is produced:

[0132]

[0133] As shown in this paper, the empirical formula does not contain subscripts a, b, and c, each indicating that the subscript is 1, which means that the ratio of dianionic pyrophosphonic acid ligand, metal atom, and monoanionic pyrophosphonic acid ligand is 1:1:1.

[0134] Typically, in many embodiments, the phosphorus-containing flame retardant compound of the extended coordination polymer as described herein constitutes all, substantially all, or at least most of the phosphorus-containing flame retardant product, such as at least 75%, 85%, 90%, 95%, 98%, or higher, or any range thereof, by weight of the flame retardant product.

[0135] The reaction mixture, typically present as a slurry, can be combined with an additional solvent, which may be the same as or different from the solvent used in the reaction mixture. The additional solvent may, for example, be selected from those solvent components described herein for phosphonic acids or pyrophosphonic acids. 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.

[0136] Optionally, a seed material can be used to facilitate the reaction. For example, using a seed material can reduce the time required to achieve conversion to a phosphorus-containing flame retardant product and can lead to increased consistency in the physical characteristics of the product. Therefore, in some embodiments, the reaction mixture further comprises a seed material. Typically, the seed material is added to the reaction mixture during or after heating to the reaction temperature. In many embodiments, the seed material is added prior to the conversion and / or precipitation of the flame retardant product. In some embodiments, the seed material comprises a phosphorus-containing flame retardant produced according to the methods disclosed herein. The seed material can be selected or refined to have a desired particle size.

[0137] In some embodiments of the solvent method, a suitable metal compound is aluminum oxide, and the phosphorus-containing flame retardant product is produced as follows:

[0138]

[0139] In one instance, it will contain phosphonic acids (such as C1-C). 12 An alkylphosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid), a solvent for the phosphonic acid (e.g., water), and an oxide, hydroxide, halide, alkoxide, carbonate, or carboxylate of Al (e.g., alumina, aluminum trichloride, aluminum trihydride, aluminum isopropoxide, aluminum carbonate, or aluminum acetate) are heated to a reaction temperature as described herein, such as about 115°C or higher, about 125°C or higher, about 150°C or higher, or about 165°C or higher. Typically, a slurry is formed as the reaction proceeds, and the solid phosphorus-containing flame retardant product can be separated by filtration to produce a product in powder or granular form. Prior to separating the solid product, the product reaction mixture may be subjected to additional post-treatment, such as cooling the product reaction mixture to a temperature above or not below the melting point of the excess phosphonic acid and combining it with an additional solvent (e.g., water) as described herein. As mentioned above, additional solvent / slurry mixtures may optionally be stirred. Solid phosphorus-containing flame retardant products can be separated by filtration, optionally washed with an additional solvent, and dried to produce a product in powder or granular form. According to the following empirical formula, the flame retardant product contains phosphorus and aluminum in a 4:1 ratio:

[0140] In other instances, the examples described above are carried out using 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 flame retardant product contains phosphorus and iron in a 4:1 ratio:

[0141]

[0142] Typically, the above-mentioned empirically formulated compounds (which in many embodiments are extended coordination polymers as described herein) constitute all, substantially all, or at least most of the phosphorus-containing flame retardant products, such as at least 75%, 85%, 90%, 95%, 98% or higher, or any range thereof, by weight of the flame retardant product.

[0143] In a further embodiment, a suitable metal compound is a metal phosphonate having the following formula:

[0144]

[0145] Where R and M are as described above, p is 2 or 3, and y is 2 or 3, such that M (+)yIt is a metal cation, where (+)y represents the charge formally assigned to the cation, and the metal phosphonate is charge-balanced (i.e., p = y). Metal phosphonates can be prepared according to methods known in the art.

[0146] In one example, a phosphonic acid (such as an alkylphosphonic acid (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid)) is combined with water (e.g., about 1:1 by weight), and stirred and cooled to below room temperature (e.g., cooled to or below 10°C, such as about 0°C). An initial metal compound is added to the mixture of phosphonic acid and water to form a metal phosphonate. The metal phosphonate is then used as a suitable metal compound to produce a phosphorus-containing flame retardant product in powder or particulate form. In embodiments involving aluminum phosphonate as a suitable metal compound, the flame retardant product contains phosphorus and aluminum in a 4:1 phosphorus to aluminum ratio according to the following empirical formula:

[0147] Compounds having empirical formulas (which in many embodiments are extended coordination polymers as described herein) typically constitute all, substantially all, or at least most of the flame retardant products, such as at least 75%, 85%, 90%, 95%, 98%, or any range thereof by weight of the flame retardant product.

[0148] Phosphorus-containing flame retardants were prepared by a melt-state method.

[0149] Phosphorus-containing flame retardants of empirical formula (I) can be prepared by reacting a metal or suitable metal compound with a stoichiometric excess of an unsubstituted or alkyl- or aryl-substituted phosphonic acid. The reaction temperature is 105°C or higher, the phosphonic acid is in a molten state at the reaction temperature, and the molar ratio of phosphonic acid to metal or suitable metal compound in the reaction mixture is greater than 4:1. In the reaction, the metal is oxidized and can be converted to its corresponding cation form by formula M. (+)y The expression is given by M, where M is a metal, (+)y represents the charge of the metal cation, and y is 2 or 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 2 or 3), X is an anion, and the values ​​of p and q provide the charge balance of the metal compound.

[0150] In another embodiment, a phosphorus-containing flame retardant having empirical formula (I) can be prepared by reacting a metal or suitable metal compound with a stoichiometric excess of an unsubstituted or alkyl- or aryl-substituted pyrophosphonic acid. The pyrophosphonic acid is in a molten state at the reaction temperature, and the molar ratio of pyrophosphonic acid to the metal or suitable metal compound in the reaction mixture is greater than 2:1.

[0151] As used herein, "stoichiometric excess" of an unsubstituted or alkyl or aryl-substituted phosphonic acid or pyrophosphonic acid relative to a metal or suitable metal compound means that the amount of phosphonic acid or pyrophosphonic acid exceeds the stoichiometry required for the reaction between the metal or suitable metal compound and the phosphonic acid or pyrophosphonic acid. As described herein, stoichiometric excess is typically expressed by the molar ratio of phosphonic acid or pyrophosphonic acid to the metal or suitable metal compound in the reaction mixture.

[0152] As described herein, an unsubstituted or alkyl- or aryl-substituted phosphonic acid or pyrophosphonic acid, used in stoichiometric excess, serves as the reagent and solvent for the reaction. The reaction product typically forms a slurry as the resulting phosphorus-containing flame retardant product precipitates from the reaction mixture. Excess phosphonic acid or pyrophosphonic acid remaining after the reaction can be removed along with any possible byproducts by filtration and / or washing (e.g., with water). In many embodiments, substantially pure flame retardant materials are produced, such as flame retardants comprising a single compound or a mixture of substantially active compounds. The conversion based on the metal or metal compound is typically high, and the product can be readily separated and optionally further purified if desired.

[0153] Typically, the molar ratio of phosphonic acid to metal or suitable metal compound in the reaction mixture is 5:1 or higher, such as about 6:1 or higher, about 8:1 or higher, or about 10:1 or higher. A larger molar excess of phosphonic acid relative to the metal or suitable metal compound can be used in the reaction mixture, such as about 12:1 or higher, about 15:1 or higher, about 20:1 or higher, about 25:1 or higher, about 30:1 or higher, or any range therebetween. Large molar excesses of phosphonic acid relative to the metal or suitable metal compound can be used. For example, molar ratios can be as high as about 50:1, up to about 100:1, up to about 300:1, up to about 500:1, or any range therebetween. However, as will be understood, at certain large molar excesses, process efficiency may be affected; for example, precipitation of the product from the reaction mixture may be hindered. In many embodiments, the molar ratio ranges from about 8:1, from about 10:1, from about 12:1, or from about 16:1 to about 100:1 or to about 50:1, such as from about 10:1, from about 15:1, from about 20:1 to about 50:1 or to about 40:1.

[0154] Typically, for pyrophosphonic acid, the molar ratio of pyrophosphonic acid to the metal or suitable metal compound in the reaction mixture is 3:1 or higher, such as about 4:1 or higher, about 6:1 or higher, or about 8:1 or higher. A larger molar excess of pyrophosphonic acid relative to the metal or suitable metal compound is usually used in the reaction mixture, such as about 10:1 or higher, about 12:1 or higher, about 15:1 or higher, about 18:1 or higher, about 20:1 or higher, or any range therebetween. Large molar excesses of pyrophosphonic acid relative to the metal or suitable metal compound can be used. For example, molar ratios can be as high as about 30:1, up to about 50:1, up to about 100:1, up to about 250:1, or any range therebetween. However, as will be understood, at certain large molar excesses, process efficiency may be affected; for example, precipitation of the product from the reaction mixture may be hindered. In many embodiments, the molar ratio ranges from about 4:1, from about 5:1, from about 6:1, or from about 8:1 to about 50:1 or to about 25:1, such as from about 5:1, from about 8:1, from about 10:1 to about 25:1 or to about 20:1.

[0155] The reaction temperature for producing phosphorus-containing flame retardants using the molten state method should be selected such that the phosphonic acid or pyrophosphonic acid is in a molten state at the reaction temperature. For example, phosphonic acid and pyrophosphonic acid (e.g., alkyl-substituted phosphonic acid or pyrophosphonic acid) are typically solids at room temperature (e.g., methylphosphonic acid melts at about 105°C, and ethylphosphonic acid melts at about 62°C), and therefore heating the phosphonic acid or pyrophosphonic acid to produce a liquefied physical state (i.e., a molten state) is generally suitable for forming a consistent reaction mixture. As those skilled in the art will understand, the desired reaction temperature for the phosphonic acid or pyrophosphonic acid to be in a molten state can vary depending on the selected reagents and thermodynamic conditions.

[0156] The reaction temperature should also be selected to promote the formation of pyrophosphonic acid ligands in the reaction products. For phosphonic acids, a reaction temperature of 105°C or higher is used. Without being bound by any particular theory, the reaction temperature is selected to produce pyrophosphonic acid ligands via one or more dehydration reactions. In many embodiments, the metal or suitable metal compound and the 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 therebetween. The reaction temperature can be higher than those mentioned above, such as up to about 350°C, up to about 400°C or higher, but it typically does not reach or exceed the boiling point of the phosphonic acid. For example, the reaction temperature can range from about 150°C to about 300°C, such as from about 150°C to about 280°C, from about 160°C to about 260°C, or from about 160°C to about 240°C. In many embodiments, the reaction 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 140°C to about 260°C. Water is formed through one or more dehydration reactions, which may potentially lead to undesirable reverse (hydrolysis) reactions. Therefore, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction, such as continuous water removal. For example, the reaction temperature can be selected above the boiling point of water to the extent necessary to evaporate at least some or a 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.

[0157] Since dehydration is unnecessary for pyrophosphonic acid, the reaction temperature of pyrophosphonic acid can be lower than the reaction temperature of the aforementioned phosphonic acids. Typically, when using pyrophosphonic acid, the limiting criterion for selecting a suitable reaction temperature is that the pyrophosphonic acid must be in a molten state at the reaction temperature. Generally, the metal or suitable metal compound reacts with pyrophosphonic acid at a temperature of 20°C or higher. In many embodiments, the metal or suitable metal compound reacts with pyrophosphonic acid at temperatures above 20°C, such as about 40°C or higher, about 60°C or higher, about 80°C or higher, about 100°C or higher, about 140°C or higher, about 180°C or higher, about 200°C or higher, or any range in between. The reaction temperature can be higher than those temperatures, such as up to about 300°C, up to about 400°C, or higher, but it typically does not reach or exceed the boiling point of pyrophosphonic acid. In many embodiments, the reaction temperature ranges from about 25°C to about 350°C, from about 25°C to about 280°C, from about 30°C to about 260°C, from about 40°C to about 260°C, from about 60°C to about 260°C, from about 80°C to about 240°C, from about 100°C to about 240°C, from about 110°C to about 240°C, or from about 120°C to about 240°C. Depending on the metal compound used, for example, to react with pyrophosphonic acid, the reaction may produce water. As described above, in some embodiments, the reaction system is designed to facilitate the removal of water from the reaction, such as continuous water removal. For example, the reaction temperature can be selected above the boiling point of water to the extent necessary to evaporate at least a portion or a 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.

[0158] The reaction can, but does not have to, be carried out under reduced pressure or vacuum.

[0159] Typically, as the reaction proceeds, the resulting phosphorus-containing flame retardant product precipitates from the product reaction mixture, forming a slurry. Therefore, the reaction typically proceeds sufficiently long to achieve this precipitation. Generally, the amount of time required to achieve at least substantially conversion to the flame retardant product, based on the metal or suitable metal compound, will depend on the reaction temperature, with higher temperatures generally resulting in shorter reaction times. In many embodiments, the metal or suitable metal compound and phosphonic acid or pyrophosphonic acid are heated at the reaction temperature for from about 0.1 to about 48 hours, such as from about 0.2 to about 36 hours, from about 0.5 to about 30 hours, from about 1 hour to about 24 hours, such as from about 1 hour to about 12 hours, from about 1 hour to about 8 hours, or from about 2 hours to about 5 hours, although other durations may be used.

[0160] The metal or suitable metal compound and a molar excess of phosphonic acid or pyrophosphonic acid can be combined in any manner suitable for forming the reaction mixture. For example, the phosphonic acid or pyrophosphonic acid can be mixed (e.g., stirred) with the metal or metal compound to form a homogeneous reaction mixture. In some embodiments, the metal or suitable metal compound is added to the phosphonic acid or pyrophosphonic acid that has been preheated to the reaction temperature. In some embodiments, the phosphonic acid or pyrophosphonic acid is preheated and stirred while melting, such as under a nitrogen atmosphere or under reduced pressure / vacuum. In further embodiments, the metal or metal compound is added as quickly as possible without causing large changes in the reaction temperature due to the exothermic nature of the reaction. In some embodiments, the phosphonic acid or pyrophosphonic acid and the metal or suitable metal compound are combined without preheating the phosphonic acid or with insufficient heating to liquefy the phosphonic acid or pyrophosphonic acid, and the components are subsequently heated to the reaction temperature. The entire amount of the metal or suitable metal compound or the phosphonic acid or pyrophosphonic acid can be added to the reaction at once or in batches. No additional solvent is required because the phosphonic acid or pyrophosphonic acid used in a molar excess acts as both a reagent and a solvent, but additional solvents may be used if necessary. In some embodiments, when using a molar ratio of phosphonic acid or pyrophosphonic acid to a metal or suitable metal compound at or near the lower limit of the molar ratio disclosed herein, an additional solvent is used.

[0161] In some embodiments, after achieving the desired conversion to the flame retardant product (e.g., complete or substantially complete conversion), the product reaction mixture is cooled to a temperature above or not below the melting temperature of the excess phosphonic acid or pyrophosphonic acid to maintain the excess phosphonic acid or pyrophosphonic acid in a liquefied state. The excess phosphonic acid or pyrophosphonic acid can be removed by filtration / washing and optionally recovered. The recovered excess phosphonic acid or pyrophosphonic acid can be recycled, for example, returned to a reactor in which a metal or suitable metal compound reacts with the phosphonic acid or pyrophosphonic acid. After conversion to the reaction product, a solvent (e.g., water, alcohol, and / or another suitable (e.g., polar) liquid) can optionally be added to dissolve or otherwise aid in the removal of the excess phosphonic acid or pyrophosphonic acid. The phosphorus-containing flame retardant product is typically separated by filtration, optionally followed by additional processing (e.g., washing, drying, sieving, etc.). The resulting phosphorus-containing flame retardant product, typically in powder or granular form, is readily processable, i.e., requiring little or no grinding, milling, or other such physical processing before use. It should be understood that the "direct" production of flame retardant materials in powder or particulate form allows for post-processing of the reaction products, such as separating the flame retardant products (e.g., separating them from excess phosphonic acid or pyrophosphonic acid or residual solvent). This can include processing the reaction products, for example, by filtration, sieving, washing, drying, etc. After the reaction, the resulting product reaction mixture (typically a slurry) can be cooled to or just above the melting temperature of the excess phosphonic acid, and the slurry can be combined with water. The water / slurry mixture can be stirred as needed to break up any large clumps that may have formed. The solid product can be separated by filtration, optionally washed with water, and dried to produce a product in powder or particulate form. In some cases, the product can be sieved to refine the particle size.

[0162] The phosphonic acid or pyrophosphonic acid used in the production of phosphorus-containing flame retardants can be the phosphonic acid or pyrophosphonic acid as described above. The method may use more than one phosphonic acid, more than one pyrophosphonic acid, or a combination of phosphonic acid and pyrophosphonic acid. In some embodiments, the phosphonic acid or pyrophosphonic acid is generated in situ. For example, preparing the reaction mixture may include preparing the phosphonic acid or pyrophosphonic acid, such as by hydrolyzing higher oligomeric phosphonic acids and / or cyclic phosphonic anhydride starting materials.

[0163] Suitable metals and metal compounds for the reaction are as described above.

[0164] This preparation method can produce a mixture of phosphorus-containing flame retardant compounds, but in many embodiments, the method produces a phosphorus-containing flame retardant product as one or primarily a compound with a high conversion rate based on a metal or metal compound, such as at least 70%, 80%, 85%, 90%, 95%, 98% or higher, or any range thereof, in contrast to mixtures of compounds obtained by prior art methods involving heat treatment of metal phosphonates, as disclosed in U.S. Patent No. 9,745,449.

[0165] Reactions according to the molten state method typically proceed as follows:

[0166]

[0167] Where M is a metal and y is 2 or 3, such that M (+)y M is a metal cation, where (+)y represents the charge of the cation; 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-balanced metal compound; R is H, alkyl, aryl, alkylaryl, or arylalkyl (as described herein); a, b, and c represent the ratios of their corresponding components relative to each other in the reaction product, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero. Typically, a is 0, 1, or 2 (e.g., 0 or 1), b is from 1 to 4 (e.g., 1 or 2), and c is 1 or 2, and the compound is charge-balanced. In some embodiments, as shown herein, R is methyl, ethyl, propyl, isopropyl, or butyl, and M is Al, Fe, Zn, or Ca. In further embodiments, X is oxygen, hydroxyl, alkoxy, or halogen.

[0168] The general reaction scheme with pyrophosphonic acid can be represented as follows:

[0169] R, M, X, p, q, y, a, b, and c are as described above.

[0170] As discussed above, similar to inorganic coordination compounds, the formula of the reaction product is empirical or idealized, such that the product can be a coordination polymer, a complex salt, a salt sharing certain atomic valences, etc. In many embodiments, the above-described reaction product represents a monomer unit (i.e., a coordination entity) of a coordination polymer, and the extended coordination polymer structure thereby forms the phosphorus-containing flame retardant disclosed herein.

[0171] In some embodiments, y is 2 (i.e., M). (+)y (where M is a divalent cationic metal), a is 0, b is 1, and c is 2. In some embodiments, the divalent cationic metal M is Mg, Ca, or Zn. In other embodiments, y is 3 (i.e., M is a divalent cationic metal). (+)y M is a trivalent cationic metal, where a is 1, b is 1, and c is 1. In some embodiments, the trivalent cationic metal M is selected from Al, Ga, Sb, Fe, Co, B, and Bi. In some embodiments, the trivalent cationic metal M is Al, Fe, Ga, Sb, or B. 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)).

[0172] In one instance, a phosphorus-containing flame retardant compound with the following empirical formula is produced:

[0173]

[0174] As mentioned above, the absence of subscripts a, b, and c in the empirical formula indicates that each subscript is 1, representing a ratio of 1:1:1 for the dianionic pyrophosphonic acid ligand, the metal atom, and the monoanionic pyrophosphonic acid ligand.

[0175] Typically, in many embodiments, the phosphorus-containing flame retardant compound of the extended coordination polymer as described herein constitutes all, substantially all, or at least most of the phosphorus-containing flame retardant product, such as at least 75%, 85%, 90%, 95%, 98%, or higher, or any range thereof, by weight of the flame retardant product.

[0176] The reaction mixture, typically present as a slurry, can be combined with a liquid (e.g., water) and stirred as needed to break up any lumps that may have formed. The solid product can be separated by filtration, optionally washed, and dried to produce a product in powder or fine particle form. In some cases, the product can be sieved to refine the particle size.

[0177] Optionally, a seed material can be used to facilitate the reaction. For example, using a seed material can reduce the time required to achieve conversion to a phosphorus-containing flame retardant product and can lead to increased consistency in the physical characteristics of the product. Therefore, in some embodiments, the reaction mixture further comprises a seed material. Typically, the seed material is added to the reaction mixture during or after heating to the reaction temperature. In some embodiments, the seed material comprises a phosphorus-containing flame retardant produced according to the methods described herein. The seed material can be selected or refined to have a desired particle size.

[0178] In some embodiments of the molten state process, a suitable metal compound is aluminum oxide, and the flame retardant material is produced as follows:

[0179]

[0180] In one instance, after melting, phosphonic acid (such as C1-C) is added under stirring (e.g., under nitrogen) 12Alkyl phosphonic acids (e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acids) are heated to or above their melting point at 105°C, such as to 115°C, 125°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, or 240°C or higher. Oxides, hydroxides, halides, alkoxides, carbonates, or carboxylates of Al (e.g., alumina, aluminum trichloride, aluminum trihydride, aluminum isopropoxide, aluminum carbonate, or aluminum acetate) are added in stoichiometric excess of the phosphonic acid under stirring, such as at a molar ratio of phosphonic acid to metal compound as described herein, for example, 5:1 or higher, 10:1 or higher, or 15:1 or higher. Typically, a slurry is formed as the reaction proceeds, and the solid flame retardant product can be separated, for example by filtration, washing, etc., to produce a product in powder or particulate form. Prior to separating the solid product, the product reaction mixture may undergo additional post-treatment, such as cooling the product reaction mixture to above or not below the melting point of the excess phosphonic acid, combining it with a liquid (e.g., water), and optionally stirring as described above. The solid flame retardant product can be separated by filtration, optionally washed with an additional solvent, and dried to produce a product in powder or granular form. According to the following empirical formula, the flame retardant product contains phosphorus and aluminum in a 4:1 ratio:

[0181] In other instances, the examples described above are carried out using 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 flame retardant product contains phosphorus and iron in a 4:1 ratio:

[0182]

[0183] Typically, the above-mentioned empirically formulated compounds (which in many embodiments are extended coordination polymers as described herein) constitute all, substantially all, or at least most of the phosphorus-containing flame retardant products, such as at least 75%, 85%, 90%, 95%, 98% or higher, or any range thereof, by weight of the flame retardant product.

[0184] In another example where the suitable metal compound is a metal phosphonate, the metal phosphonate is prepared by mixing a phosphonic acid (such as an alkylphosphonic acid, e.g., methyl, ethyl, propyl, isopropyl, butyl, or tert-butylphosphonic acid) and a solvent (e.g., water) to form a homogeneous solution. For example, any convenient water-to-phosphonic acid ratio can be used, such as 10:1 to 1:10 by weight, 5:1 to 1:5 by weight, or 2:1 to 1:2 by weight. The solution can be cooled, for example, in the range from about 0°C to about 20°C, and an initial metal compound (such as a metal oxide, halide, alkoxide, or hydroxide) is added to react with the phosphonic acid. The metal phosphonate is formed and then used as a suitable metal compound for the production of phosphorus-containing flame retardants. For example, a molar excess of phosphonic acid (e.g., a molar ratio of phosphonic acid to metal phosphonate of 5:1) as described herein is preheated to a molten state and reacted with the metal phosphonate to form a phosphorus-containing flame retardant product. In embodiments involving aluminum phosphonate as a suitable metal compound, the flame retardant product contains phosphorus and aluminum in a 4:1 ratio according to the following empirical formula:

[0185] Compounds having empirical formulas (which in many embodiments are extended coordination polymers as described herein) typically constitute all, substantially all, or at least most of the flame retardant products, such as at least 75%, 85%, 90%, 95%, 98%, or any range thereof by weight of the flame retardant product.

[0186] Preparation of flame-retardant thermoplastic compositions

[0187] This invention is not limited to any particular method of blending the components of the flame-retardant thermoplastic compositions disclosed herein. Suitable compounding and blending techniques known in the art can be used. For example, one method involves blending a thermoplastic polymer in powder or granular form with a flame-retardant additive and melt-blending the blend (e.g., using a twin-screw extruder). Optionally, other additives (including, but not limited to, fillers, such as glass fibers or other types of fillers) are also extruded together. The thermoplastic polymer, flame-retardant additive, and other additives are typically pre-dried prior to melt blending. The extruded blend can be pulverized into granules or other suitable shapes using standard techniques. Other melt-blending process equipment, such as kneader mixers or bowl mixers, can be used to compound the flame-retardant additive and any additional components with the thermoplastic polymer. In either case, a generally suitable machine temperature can range from about 230°C to 330°C, depending on the specific type of thermoplastic plastic selected.

[0188] Flame-retardant thermoplastic compositions can be molded in any equipment suitable for this purpose, such as an injection molding machine. After granulation, the granules are typically dried again before molding in an injection molding machine suitable for this purpose. Generally, the processing temperature ranges from about 250°C to 280°C, depending on the molding characteristics of the specific thermoplastic polymer, the loading level of additives and / or reinforcing fillers, and other factors (such as the thickness of the mold cavity and the gate size). Those skilled in the art will be able to make appropriate adjustments during the molding process to accommodate differences in composition or tooling.

[0189] In another embodiment, the molded article comprises a flame-retardant thermoplastic composition as disclosed herein, wherein the molded article is manufactured by injection molding. Flame-retardant thermoplastic compositions are useful, for example...

[0190] In the production of electronic components such as connectors, frames, moving parts, transformers, and micro motors, etc. In a further embodiment, injection-molded parts, such as electronic components, are provided that comprise a flame-retardant thermoplastic composition as disclosed herein.

[0191] Additional non-restrictive disclosures are provided in the following examples.

[0192] Example

[0193] Example 1

[0194] Methylphosphonic acid (MPA) (3678.8 g, 38.3 mol, 30 equivalents, 75% aqueous solution) and alumina (130.2 g, 1.28 mol, 1 equivalent) were mixed at room temperature, where limited exothermic reaction (increase of about 2 °C) was observed. The tank temperature was set to 165 °C, with the stirrer at 200 RPM at atmospheric pressure and nitrogen purging (4 L / min). Optionally, 1.0 g of crystallizing agent, a flame retardant product produced from MPA and alumina as described herein, was added when no distilled water was observed at the condenser. The reaction mixture was heated at 165 °C for 3 hours. The product reaction mixture containing the white slurry product was then cooled to about 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The white slurry was then filtered off, washed with water (500 mL × 3), and dried to produce fine crystals in 92% yield. The product has a phosphorus-aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0195]

[0196] The empirical formulas above represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form the pure crystalline product. Thermogravimetric analysis (TGA) of the product is shown in... Figure 1 middle.

[0197] Example 2

[0198] 800 mL of xylene was added to a 1 L flask equipped with a Dean-Stark water separator. The solution was heated to 115 °C and methylphosphonic acid (MPA) (33.89 g, 0.35 mol) was added. The acid was dissolved, and the temperature was increased until the solution began to reflux. Alumina (4.01 g, 0.039 mol) was added in portions over 3 hours. The reflux was maintained at 142 °C overnight. The resulting solid product was separated by filtration, washed with DMF (100 mL) and Et₂O (2 × 50 mL), and dried to produce a fine powder (18.86 g, 71% yield). According to the following empirical formula, the product has a phosphorus-aluminum ratio of 4:1:

[0199]

[0200] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0201] Example 3

[0202] Methylphosphonic acid (MPA) (2216 g, 23.1 mol, 15 equivalents, aqueous solution) and aluminum trioxide (120 g, 1.5 mol, 1 equivalent) were mixed at room temperature. The tank temperature was set to 165 °C, with the stirrer at 200 RPM at atmospheric pressure and nitrogen purging (4 L / min). Optionally, 1.0 g of crystallizing agent, a flame retardant product produced as described herein from MPA and aluminum trioxide, was added when no distilled water was observed at the condenser. The reaction mixture was heated at 165 °C for 3 hours. The product reaction mixture containing the white slurry product was then cooled to approximately 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The white slurry was filtered off, washed with water (500 mL × 3), and dried to produce fine crystals in approximately 100% yield. The product has a phosphorus-to-aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0203]

[0204] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0205] Example 4

[0206]

[0207] Methylphosphonic acid (MPA) (1412.6 g, 14.7 mol, 30 equivalents, 75% aqueous solution) and iron oxide (78.2 g, 0.49 mol, 1 equivalent) were mixed at room temperature. The tank temperature was set to 130 °C for approximately 12 hours, with the stirrer purged with nitrogen at 250 RPM (4 L / min) under atmospheric pressure. The reaction mixture was then heated to 165 °C for 12 hours. The product reaction mixture containing the off-white slurry was then cooled to approximately 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The off-white slurry was filtered off, washed with water (500 mL × 3), and dried to produce fine off-white crystals in 92% yield. The product has a phosphorus-to-iron ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0208]

[0209] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0210] Example 5

[0211]

[0212] Methylphosphonic acid (MPA) (1727 g, 18.4 mol, 15 equivalents, 75% aqueous solution) was cooled to 5 °C in an ice-water bath under a nitrogen flow (1 L / min). Aluminum isopropoxide (250 g, 1.2 mol, 1 equivalent) was added in portions while maintaining the tank temperature below 10 °C. The tank temperature was then set to 165 °C with the stirrer at 250 RPM. At 165 °C, optionally 4.5 g of a crystal-inducing material, a flame retardant product prepared from MPA and aluminum isopropoxide as described herein, was added, and the reaction mixture was maintained at 165 °C for 3 hours. The product reaction mixture containing the white slurry product was then cooled to approximately 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The white slurry was filtered off, washed with water (500 mL × 3), and dried to produce fine crystals in 44% yield. Based on the following empirical formula, the product has a phosphorus-to-aluminum ratio of 4:1 (ICP elemental analysis):

[0213]

[0214] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0215] Example 6

[0216]

[0217] Ethylphosphonic acid (EPA) (55.0 g, 0.50 mol, 30 equivalents) and alumina (1.70 g, 17 mmol, 1 equivalent) were mixed with 50 mL of water at room temperature. The tank temperature was set to 165 °C, with the stirrer at 250 RPM at atmospheric pressure and nitrogen purging (4 L / min). The reaction mixture was heated at 165 °C for 3 hours. The product reaction mixture containing the white slurry was then cooled to approximately 130 °C and poured into 100 mL of water in a beaker cooled in an ice-water bath. The white slurry was filtered off, washed with water (50 mL × 3), and dried to produce fine crystals in 76% yield. The product has a phosphorus-aluminum ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0218]

[0219] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0220] Example 7

[0221]

[0222] 114.6 g of methylphosphonic acid was added to a 250 mL three-necked flask and then heated. The methylphosphonic acid melted at 105 °C, and vigorous stirring was initiated under N2 cover. The methylphosphonic acid was heated to 240 °C, and 7.78 g of alumina was added as quickly as possible without causing significant exothermic reactions. The slurry was cooled until it was just above the melting point of the excess methylphosphonic acid (approximately 110 °C) and then added to 250 mL of H2O, ensuring that the rate of addition did not result in excessive vapor formation. The resulting mixture was stirred to break up any large clumps that may have formed, the product was separated by filtration, washed with an additional 750 mL of H2O, and dried to yield 45.08 g of a product in 87% yield as fine, colorless crystals. The empirical formula for the above product represents the repeating monomer unit (i.e., the coordination entity) of the coordination polymer that forms the pure crystalline product. Thermogravimetric analysis (TGA) of the product is shown in [Figure / Insert Figure ... Figure 2 middle.

[0223] Example 8

[0224]

[0225] 149.8 g of ethylphosphonic acid was added to a 250 mL three-necked flask and heated to melt (62 °C). Vigorous stirring was initiated under N2 cover, and the ethylphosphonic acid was heated to 240 °C. 6.9 g of alumina was added as quickly as possible without causing significant exothermic reaction. The slurry was cooled to approximately 80 °C and then added to 250 mL of H2O, ensuring that the rate of addition did not result in excessive vapor formation. The resulting mixture was stirred to break up any large clumps that may have formed. The product was separated by filtration, washed with an additional 750 mL of H2O, and dried to yield 49.07 g of a product in 84% yield, in the form of fine, colorless crystals. The empirical formula for the above product represents the repeating monomeric unit (i.e., the coordination entity) of the coordination polymer that forms the pure crystalline product.

[0226] Example 9

[0227]

[0228] 83 g of methylphosphonic acid was added to a resin reactor and heated to 120 °C. An intermediate material prepared from 50 g of methylphosphonic acid and 35.4 g of tris(isopropoxy)aluminum in the presence of water was added to the resin reactor as a slurry. The resulting solution contained a methylphosphonic acid intermediate with a methylphosphonic acid:aluminum molar ratio of 5:1. This solution was heated to 240 °C with mechanical stirring. After solidification, stirring was continued at 240 °C for approximately 30 min. 500 mL of H₂O was added, and the mixture was stirred for 16 h to prepare a homogeneous slurry. As described above, the product was separated by filtration, washed with an additional 750 mL of H₂O, and dried to produce 64.3 g of a product in 93% yield, in the form of fine, colorless crystals. The empirical formula for the above product represents the repeating monomer unit (i.e., the coordination entity) of the coordination polymer that forms the pure crystalline product.

[0229] Example 10

[0230]

[0231] 1305 g of methylphosphonic acid was added to a 1 L three-necked flask and then heated. The methylphosphonic acid melted at 105 °C, and vigorous stirring was initiated under vacuum. The methylphosphonic acid was heated to 180 °C, and 61 g of alumina was added as quickly as possible without causing excessive exothermic reaction or excessive foaming. The slurry was cooled until it was just above the melting point of the excess methylphosphonic acid (approximately 110 °C) and then added to 1 L of H₂O, ensuring that the rate of addition did not result in excessive vapor formation. The resulting mixture was stirred to break up any large clumps that may have formed, and the product was separated by filtration, washed with an additional 1.5 L of H₂O, and dried to produce 408 g of fine, colorless crystals in 84% yield. The empirical formula for the above product represents the repeating monomeric unit (i.e., the coordination entity) of the coordination polymer that forms the pure crystalline product.

[0232] The products from each of Examples 7-10 have a P / Al ratio of 4:1 (ICP elemental analysis).

[0233] Example 11

[0234]

[0235] 1412.6 g of methylphosphonic acid was charged into a 1 L reaction vessel and heated to 165 °C with stirring at 250 RPM under nitrogen purging (4 L / min). 78.2 g of ferric oxide was added in portions without causing significant exothermic reactions. The reaction mixture was heated at 165 °C for approximately 24 hours. The product reaction mixture containing the off-white slurry was then cooled to approximately 130 °C and poured into 1.5 L of water in a beaker cooled in an ice-water bath. The product was separated by filtration, washed with an additional 500 mL × 3 of water, and dried to yield fine off-white crystals in 83% yield. The product has a phosphorus-to-iron ratio of 4:1 according to the following empirical formula (ICP elemental analysis):

[0236]

[0237] The above empirical formulas represent the repeating monomer units (i.e., coordination entities) of the coordination polymer that form pure crystalline products.

[0238] Example 12

[0239] Flame-retardant polymer compositions were compounded and molded into 1.6 mm strips, and their flame-retardant activity was evaluated under UL-94 testing according to Table 1 below. The following formulations were compounded using a twin-screw extruder at barrel temperatures between 250°C and 260°C. Formulation 1 contains 470 g of glass-filled polyamide-6 (from LANXESS). B30S), 250g glass fiber (from PPG). 3540), 220 grams of poly(dibromostyrene) flame retardant (from Lanxess, under the trade name) A blend of PBS-64HW (for sale) and 60 grams of phosphorus-containing flame retardant (Phos-FR) produced according to Example 7 above. Formulation 2 is identical except that it is produced according to Example 1 above. 1 / 16-inch (thickness) UL-94 specimens were prepared for each formulation using an injection molding machine at a barrel temperature of 250°C–260°C and a mold temperature of 80°C.

[0240] Table 1

[0241]

[0242]

[0243] Although specific embodiments of the invention have been described and illustrated, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the claimed invention by considering the specification and practice of this disclosure. Therefore, this specification and examples should be understood as exemplary only, wherein the true scope of the invention is indicated by the following claims and their equivalents.

Claims

1. A flame-retardant thermoplastic composition free of antimony trioxide, wherein, based on the total weight of the flame-retardant thermoplastic composition, the composition comprises: (a) at least one thermoplastic polymer in a weight percentage of 30 to 95%; (b) at least one brominated flame retardant of 3 to 30% by weight; and (c) At least one phosphorus-containing flame retardant having empirical formula (I) in a weight percentage of 1 to 10 percent: (I)， Where R is H, alkyl, or aryl, 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 these components in the compound relative to each other, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero and a is not zero.

2. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 1, wherein, The at least one thermoplastic polymer is selected from the group consisting of polyester and polyamide.

3. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 2, wherein, The at least one thermoplastic polymer is a polyester selected from polyalkylene terephthalate.

4. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 3, wherein, The thermoplastic polymer is selected from the following polyesters: polyethylene terephthalate, poly(1,3-propanediol terephthalate), poly(1,4-butanediol terephthalate), and mixtures thereof.

5. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 2, wherein, The at least one thermoplastic polymer is a polyamide selected from the group consisting of: polyamide-4,6, polyamide-6, polyamide-6,6, polyamide-6,10, polyamide-6,12, polyamide-11, polyamide-12 and mixtures thereof.

6. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 2, wherein, The at least one thermoplastic polymer is a polyamide selected from the group consisting of: polyamide-4,T, polyamide-MXD,6, polyamide-12,T, polyamide-10,T, polyamide-9,T, polyamide-6,T / 6,6, polyamide-6,T / D,T, polyamide-6,6 / 6,T / 6,I, polyamide-6 / 6,T, polyamide-6,T / 6,I, and mixtures thereof.

7. The flame-retardant thermoplastic composition free of antimony trioxide as described in any of the preceding claims, wherein, The at least one brominated flame retardant is selected from the group consisting of: decabromodiphenyl ether, decabromodiphenyl ethane, tetrabromobisphenol A, tetrabromobisphenol A bis(2,3-dibromopropyl ether), tris(tribromophenoxy)triazine, tris(tribromoneopentyl)phosphate, brominated polyacrylate, brominated polystyrene, polybromostyrene, brominated epoxy polymer, phenoxy-terminated carbonate oligomer of tetrabromobisphenol A, tetradecylbromodiphenoxybenzene, ethylene bis(tetrabromophthalimide), tetrabromobisphenol S bis(2,3-dibromopropyl ether), poly-dibromophenyl ether, brominated styrene-butadiene-styrene copolymer, 2-ethylhexyltetrabromophthalate, and bis(tribromophenoxy)ethane.

8. The flame-retardant thermoplastic composition free of antimony trioxide as described in any one of claims 1-6, wherein, a is 0, 1, or 2, b is 1 to 4, and c is 1 or 2.

9. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 8, wherein, a is 1, b is 1, and c is 1.

10. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 9, wherein, M is selected from Al, Ga, Sb, Fe, Co, B and Bi.

11. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 10, wherein, M is either Al or Fe.

12. The flame-retardant thermoplastic composition free of antimony trioxide as described in any one of claims 1-6, wherein, R is H, C 1-12 Alkyl or C 6-10 Aryl group, wherein the alkyl or aryl 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.

13. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 12, wherein, R is unsubstituted C. 1-12 Alkyl or C6 aryl.

14. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 12, wherein, R is unsubstituted C. 1-6 alkyl.

15. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 12, wherein, R is selected from methyl, ethyl, propyl, isopropyl, butyl, and tert-butyl.

16. The flame-retardant thermoplastic composition free of antimony trioxide as described in any one of claims 1-6, wherein, M is Al, a is 1, b is 1 and c is 1.

17. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 16, wherein, R is H or C 1-6 alkyl.

18. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 17, wherein, R is selected from methyl and ethyl.

19. The flame-retardant thermoplastic composition free of antimony trioxide as claimed in any one of claims 1-6, the composition further comprising an inorganic filler.

20. The flame-retardant thermoplastic composition free of antimony trioxide as described in claim 19, wherein, The inorganic filler is glass fiber.

21. A flame-retardant article comprising a flame-retardant thermoplastic composition free of antimony trioxide according to any one of the preceding claims.

22. A method for preparing a flame-retardant thermoplastic composition, the method comprising: Based on the total weight of the flame-retardant thermoplastic composition, the blending (a) at least one thermoplastic polymer in a weight percentage of 30 to 95%; (b) at least one brominated flame retardant, comprising 3 to 30% by weight; as well as (c) 1 to 10% by weight of at least one phosphorus-containing flame retardant having empirical formula (I) (I)， Where R is H, alkyl, or aryl, 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 these components in the compound relative to each other, and satisfy the charge balance equation 2(a) + c = b(y), where c is not zero and a is not zero.

23. A method for preparing a flame-retardant article, the method comprising molding a flame-retardant thermoplastic composition free of antimony trioxide according to any one of claims 1-20.

24. The method of claim 23, wherein, This antimony trioxide-free flame-retardant thermoplastic composition is injection molded.

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