A polyphosphate compound, a method for preparing the same, and an application thereof

Abstract

This invention relates to a polyphosphate compound, its preparation method, and its applications. The preparation method of the polyphosphate compound includes the following steps: reacting a diphenolic compound with a phosphate compound under the action of carbonates and borates to obtain the polyphosphate compound. The preparation method of the polyphosphate compound provided by this invention is simple in process and convenient in post-processing. While effectively increasing the phosphorus content of the obtained polyphosphate compound, it also reduces the reaction temperature, avoiding the stringent high-temperature requirements of existing condensation-type flame retardant synthesis.

Description

Technical Field

[0001] This invention relates to the field of flame retardant technology, and in particular to a polyphosphate compound, its preparation method, and its application. Background Technology

[0002] With the development trend of halogen-free, low-toxicity and environmentally friendly flame retardants in the flame retardant industry, traditional halogen flame retardants are gradually being restricted. Condensed phosphate esters have become ideal substitutes due to their low toxicity, low smoke and halogen-free properties, and demand has surged, especially in the fields of electronics, automotive interiors and building materials.

[0003] Currently, existing condensation phosphate flame retardants suffer from problems such as low degree of polymerization, poor hydrolysis resistance, and high selectivity for substrates. For example, aromatic condensation phosphates (such as BDP) perform well in engineering plastics, but have poor compatibility in non-polar systems such as polyolefins (PP, PE) and natural fiber composites. They require the addition of compatibilizers or compound modifiers, which increases production costs and process complexity. Moreover, their flame retardant effect is limited and requires a higher addition amount than halogenated flame retardants to achieve the same flame retardant effect.

[0004] Meanwhile, the synthesis of existing condensation-type flame retardants requires a high temperature of at least 250-300℃ and has high requirements for the selection of catalysts.

[0005] Therefore, developing a method for preparing a polyphosphate compound with excellent flame retardant properties has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a polyphosphate compound, its preparation method, and its applications. The preparation method for the polyphosphate compound is simple and convenient for post-processing, effectively solving the problems of low polymerization degree and harsh high-temperature synthesis conditions required by existing condensation-type flame retardants. The resulting polyphosphate compound exhibits suitable viscosity and weight-average molecular weight, as well as high phosphorus content, resulting in excellent flame retardant properties. It also demonstrates good compatibility with polymer materials and good hydrolysis resistance, providing better flame retardant solutions for various industries.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a polyphosphate compound, the method comprising the following steps: The polyphosphate compound is obtained by reacting a diphenolic compound with a phosphate ester compound in the presence of carbonate and borate.

[0008] The method for preparing polyphosphate compounds provided by this invention uses carbonate and borate as a composite catalyst, which can effectively catalyze the forward reaction of diphenolic compounds and phosphate compounds as raw materials, thereby increasing the chain length and degree of polymerization of the polycondensation, and thus increasing the phosphorus content and weight-average molecular weight of the obtained polyphosphate compound, thereby enhancing its flame retardant effect. At the same time, it also effectively avoids the complex post-polymerization purification steps, making the entire preparation method simple and convenient for post-processing. In addition, the preparation method provided by this invention can also reduce the reaction temperature, so that the reaction temperature does not exceed 250°C, thereby avoiding the harsh high-temperature requirements of existing polycondensation flame retardants and effectively solving the problems of low degree of polymerization and harsh high-temperature synthesis conditions of existing polycondensation flame retardants.

[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0010] As a preferred embodiment of the present invention, the diphenolic compound is selected from any one of bisphenol A, bisphenol F, bisphenol S, resorcinol, catechol, or hydroquinone.

[0011] In this invention, by optimizing the specific types of diphenolic compounds, precise control of the molecular structure and degree of polymerization of polyphosphate compounds can be achieved, significantly improving their flame retardancy, thermal stability, mechanical compatibility, and processing adaptability, while retaining the original properties of the substrate. When the compound is a bisphenol (bisphenol A, bisphenol F, bisphenol S), the resulting polyphosphate compound is a bisphenol-type phosphate compound. The rigid biaromatic ring skeleton in its structure enables the bisphenol-type phosphate compound to possess both high-efficiency flame retardancy and excellent mechanical properties. It can not only rapidly form a barrier char layer at high temperatures, but also optimize its compatibility with polymer substrates and processing fluidity, making it suitable for industrial applications.

[0012] Preferably, the molar ratio of the phosphate ester compound to the diphenol compound is (1.0-1.2):1, wherein (1.0-1.2) can be, for example, 1.0, 1.02, 1.05, 1.08, 1.1, 1.12, 1.15, 1.18 or 1.2, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0013] This invention optimizes the molar ratio of phosphate esters to diphenols, enabling precise control of the molecular chain structure and functional group distribution of polyphosphate compounds, thus improving their flame retardant efficiency and thermal stability. When the molar ratio is low, insufficient supply of functional groups from phosphate esters during polymerization disrupts the equimolar ratio of transesterification, significantly reducing polymer molecular weight, increasing phenolic hydroxyl end-capping, decreasing thermal stability, and lowering phosphorus content, ultimately leading to simultaneous deterioration of both flame retardant efficiency and processing performance. Conversely, when the molar ratio is high, the product is predominantly phosphate-terminated with low end-group activity, making further polycondensation difficult. This results in a wider polydispersity index (PDI), limited chain growth, lower molecular weight, decreased product purity, increased residual monomers, altered branching / crosslinking tendencies, and decreased thermal stability.

[0014] Preferably, the phosphate ester compound has the structure shown in Formula I: Formula I; Wherein, R1 is selected from any one of substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C6-C18 aryl, or substituted or unsubstituted C4-C10 heteroaryl; R2 is selected from any one of substituted or unsubstituted C1-C8 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C12 aryl, and substituted or unsubstituted C3-C12 heteroaryl. R3 is selected from halogens or -OR4; R4 is selected from any one of substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C6-C18 aryl, or substituted or unsubstituted C4-C10 heteroaryl; The substituent group is selected from any one of C1-C3 alkyl groups.

[0015] Preferably, R1 is selected from any one of C1-C3 alkyl and C6-C12 aryl; R2 is selected from any one of C1-C6 alkyl, C3-C6 cycloalkyl, C6-C12 aryl, and C3-C12 heteroaryl, and is more preferably C1-C4 alkyl; R4 is selected from any one of C1-C3 alkyl or C6-C12 aryl.

[0016] In this invention, C6-C18 can be C6, C10, C12, C14, C16, or C18, etc.; C4-C10 can be C4, C5, C6, C7, C8, C9, or C10; C1-C8 can be C1, C2, C3, C4, C5, C6, C7, or C8; C3-C8 can be C3, C4, C5, C6, C7, or C8; and C6-C12 can be C6, C10, C12, C13, C14, C15, C16, C17, or C18. C10, C11 or C12; C3-C12 can be C3, C4, C, C5, C6, C7, C8, C9, C10, C11 or C12; C1-C3 can be C1, C2 or C3; C1-C6 can be C1, C2, C3, C4, C5 or C6; C3-C6 can be C3, C4, C5 or C6; C1-C4 can be C1, C2, C3 or C4.

[0017] Preferably, the phosphate ester compound includes any one or a combination of at least two of methyl chlorophosphate (a), methyl chlorophosphate, diphenyl methyl phosphate, or dimethyl methylphosphonate, and more preferably methyl chlorophosphate.

[0018] The structure of phenyl methyl chlorophosphate (a) is as follows: (a).

[0019] In this invention, by selecting the specific types of phosphate ester compounds, the reactivity matching degree between them and diphenol compounds can be optimized, side reactions can be reduced, and the controllability of the polymerization process and the stability of product performance can be ensured. Furthermore, when the phosphate ester compound is methyl chlorophosphate phenyl ester, the high temperature requirement of the reaction can also be reduced.

[0020] Preferably, the molar ratio of the carbonate to the diphenol compound is (0.5-0.7):1, wherein (0.5-0.7) can be, for example, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68 or 0.7, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0021] Preferably, the carbonate includes any one or a combination of at least two of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, or potassium bicarbonate, and more preferably potassium carbonate.

[0022] This invention optimizes the types of carbonates to further enhance the polymerization rate and selectivity of phosphate esters and diphenols, reduce byproduct formation, lower activation energy, and optimize reaction conditions. Potassium carbonate, as a strong base carbonate, exhibits a suitable interaction strength between its carbonate ions and the phenolic hydroxyl groups of diphenols. This interaction allows for the efficient extraction of protons from the phenolic hydroxyl groups, promoting the generation of phenoxy anions. Consequently, it significantly enhances the nucleophilic substitution reaction of phenoxy anions with halogen atoms in phosphate esters, or their transesterification reaction with phosphate diesters, accelerating polymer chain growth.

[0023] Preferably, the molar ratio of the borate to the diphenol compound is (0.001-0.003):1, wherein (0.001-0.003) can be, for example, 0.001, 0.0012, 0.0014, 0.0016, 0.0018, 0.002, 0.0022, 0.0024, 0.0026, 0.0028 or 0.003, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0024] This invention optimizes the molar ratio of borates to diphenolic compounds, enabling more precise control of the polymerization rate and reaction pathway, thereby improving the molecular weight uniformity, structural regularity, and flame retardant-mechanical property synergy of polyphosphate products. When the molar ratio of the two is low, the supply of catalytic active sites of borate is insufficient, making it difficult to fully activate the phenolic hydroxyl groups in the diphenolic compound. This leads to a significant slowdown in the polymerization rate, incomplete reaction, reduced product yield, and high oligomer content, resulting in uneven distribution of flame-retardant functional groups (phosphate groups). Furthermore, when borate is absent, the viscosity, phosphorus content, and weight-average molecular weight of the resulting polyphosphate compound are significantly reduced, resulting in poor flame-retardant effect. When the molar ratio of the two is high, excess borate will form redundant catalytic sites in the reaction system, initiating chain termination reactions or excessive cross-linking, leading to abnormal product molecular weight, increased molecular chain branching, significantly increased melt viscosity, and increased construction difficulty. At the same time, the weight-average molecular weight increases significantly, thus affecting the compatibility of the resulting polyphosphate compound with other polymer materials. Moreover, the excessively high weight-average molecular weight of the polyphosphate compound increases its strength, thereby affecting its processing performance in practical applications.

[0025] Preferably, the borate includes tetraphenylborate and / or tetraphenylphosphonium tetraphenylborate, and more preferably tetraphenylborate.

[0026] This invention optimizes the types of borates to more precisely control the growth rate and structural regularity of polyphosphate molecular chains, while enhancing the synergistic flame-retardant effect of the product. When it is a tetraphenylborate, the phenyl substitution structure of sodium tetraphenylborate imparts a suitable steric hindrance effect, enabling it to form a specific interaction with the phenolic hydroxyl groups of diphenolic compounds, efficiently activating polymerization reaction sites (promoting the generation of phenoxy anions, accelerating nucleophilic substitution reactions with halophosphates or transesterification reactions with phosphate diesters), and inhibiting side reactions such as excessive crosslinking or chain termination. This results in polyphosphate compounds with both higher flame retardancy and better overall performance.

[0027] Preferably, the tetraphenylborate comprises any one or a combination of at least two of sodium tetraphenylborate, potassium tetraphenylborate, or ammonium tetraphenylborate.

[0028] Preferably, the reaction is carried out under solvent-free conditions.

[0029] The method for preparing polyphosphate compounds provided by this invention does not require the addition of additional solvents to carry out the reaction, which not only saves raw material costs, but also avoids environmental pollution caused by the use of large amounts of solvents, making it green, environmentally friendly and economical.

[0030] Preferably, the reaction includes a first-stage reaction, a second-stage reaction, and a third-stage reaction.

[0031] In this invention, the first stage reaction is a substitution reaction or transesterification reaction, and the second and third stage reactions are transesterification polymerization reactions. In the transesterification polymerization reaction, a low-molecular-weight polymerization is first carried out using a pre-condensation reaction at a lower temperature (second stage reaction), and then the temperature is increased (third stage reaction) to carry out high-molecular-weight polymerization. By using gradient temperature polymerization, the polymerization effect can be improved, resulting in a higher degree of polymerization, thereby obtaining a polyphosphate compound with higher phosphorus content, more suitable weight-average molecular weight, and viscosity.

[0032] By selecting appropriate reactants and catalysts (carbonate + borate), this invention can reduce the temperature of the transesterification reaction during the preparation of traditional condensation-type phosphate flame retardants to a certain extent, resulting in milder reaction conditions.

[0033] Preferably, the temperature of the first stage reaction is 160-200℃, for example, it can be 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0034] Preferably, the reaction time of the first stage is 3-6 hours, for example, it can be 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, 4 hours, 4.2 hours, 4.5 hours, 4.8 hours, 5 hours, 5.2 hours, 5.5 hours, 5.8 hours or 6 hours, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] Preferably, the temperature of the second stage reaction is 200-230°C, for example, it can be 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0036] Preferably, the reaction time of the second stage is 3-6 h, for example, it can be 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, 5 h, 5.2 h, 5.5 h, 5.8 h or 6 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0037] Preferably, the temperature of the third stage reaction is 230-250℃, for example, it can be 230℃, 232℃, 235℃, 238℃, 240℃, 242℃, 245℃, 248℃ or 250℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0038] Preferably, the reaction time of the third stage is 3-7 h, for example, it can be 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h or, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0039] Preferably, both the first-stage reaction and the second-stage reaction are carried out under a protective gas atmosphere.

[0040] Preferably, the protective gas includes any one or a combination of at least two of argon, nitrogen, or helium.

[0041] Preferably, the third-stage reaction is carried out under vacuum conditions.

[0042] In the third stage of the reaction, the present invention performs a vacuum operation, which can effectively remove low-boiling-point byproducts such as phenol and hydrogen chloride, thereby promoting the forward reaction and improving the purity of the obtained polyphosphate compound.

[0043] Preferably, the specific preparation method of the polyphosphate compound includes the following steps: The diphenolic compound, phosphate ester compound, carbonate and borate are mixed and subjected to a first-stage reaction at 160-200℃ for 3-6 h under a protective gas atmosphere. The temperature is then raised to 200-230℃ for a second-stage reaction for 3-6 h. The protective gas is then stopped, a vacuum operation is performed, and a third-stage reaction is carried out at 230-250℃ for 3-7 h to obtain the polyphosphate ester compound.

[0044] In a second aspect, the present invention provides a polyphosphate compound, which is prepared by the method for preparing polyphosphate compounds as described in the first aspect.

[0045] The polyphosphate compound provided by this invention is a high molecular weight halogen-free phosphorus-containing polymer with suitable viscosity and weight-average molecular weight, high degree of polymerization, high phosphorus content, and excellent flame retardant properties. It has good compatibility with polymer materials and good hydrolysis resistance, and can be used to prepare a variety of flame retardant polymer materials such as flame retardant polyurethane, flame retardant polyester, and flame retardant polyamide, with a wide range of applications.

[0046] Preferably, the weight-average molecular weight of the polyphosphate compound is 60,000 to 150,000, for example, it can be 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000 or 150,000, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. More preferably, it is 70,000 to 130,000, and even more preferably, it is 90,000 to 110,000.

[0047] Preferably, the viscosity of the polyphosphate compound is 0.5-1 g / dL, for example, it can be 0.5 g / dL, 0.55 g / dL, 0.6 g / dL, 0.65 g / dL, 0.7 g / dL, 0.75 g / dL, 0.8 g / dL, 0.85 g / dL, 0.9 g / dL, 0.95 g / dL or 1 g / dL, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. More preferably, it is 0.55-0.95 g / dL, and even more preferably, it is 0.65-0.8 g / dL.

[0048] Preferably, the phosphorus content of the polyphosphate compound is 8-12%, for example, it can be 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. More preferably, it is 9-11%, and even more preferably, it is 10-11%.

[0049] Thirdly, the present invention provides a phosphate flame retardant, the phosphate flame retardant comprising a polyphosphate compound prepared by the method for preparing polyphosphate compounds as described in the first aspect, or a polyphosphate compound as described in the second aspect.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The preparation method of polyphosphate ester compounds provided by the present invention uses carbonate and borate as composite catalysts, and diphenolic compounds and phosphate ester compounds as reaction raw materials. The preparation process is simple to operate, convenient to post-process, and the reaction temperature is not higher than 250℃. It effectively solves the problems of low degree of polymerization and harsh high temperature synthesis conditions of existing condensation flame retardants.

[0051] (2) Further, the polyphosphate compound prepared by the method of the present invention is a high molecular weight halogen-free phosphorus-containing polymer (weight average molecular weight of 60,000-150,000), with suitable viscosity (0.5-1 g / dL), high degree of polymerization, high phosphorus content (8-12%), excellent flame retardant properties, good compatibility with polymer materials and good hydrolysis resistance. It can be used to prepare a variety of flame retardant polymer materials such as flame retardant polyurethane, flame retardant polyester, and flame retardant polyamide, and has a wide range of applications. Attached Figure Description

[0052] Figure 1 The infrared spectrum of the polyphosphate compound obtained in Example 1; Figure 2 The thermogravimetric analysis (TGA) spectrum of the polyphosphate compound obtained in Example 1. Detailed Implementation

[0053] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0054] Unless otherwise specified, the materials and equipment involved in the following detailed embodiments are all conventional materials and equipment in the art and will not affect the technical effects of the present invention.

[0055] Unless otherwise specified, all reagents and raw materials used in the following examples and comparative examples are commercially available products.

[0056] Example 1 This embodiment provides a phosphate ester compound and its preparation method, the preparation method comprising the following steps: Bisphenol A (60 g, 0.26 mol), phenyl methyl chlorophosphate (52.02 g, 0.27 mol), potassium carbonate (17.97 g, 0.13 mol), and sodium tetraphenylborate (0.17 g, 0.0005 mol) were added to a 250 mL three-necked flask equipped with a stirrer. The first stage reaction was carried out at 180 °C for 3 h under nitrogen protection. After the reaction of the raw materials was completed by liquid phase monitoring, the temperature was raised to 220 °C for the second stage reaction for 3 h. The nitrogen gas supply was stopped, and a vacuum operation was performed. The third stage reaction was carried out at 240 °C for 3 h to obtain a light yellow solid product, namely the polyphosphate compound.

[0057] like Figure 1 As shown in the infrared spectrum of the polyphosphate compound, 2966.20 cm⁻¹ -1 The peak indicates the methyl group, at 1602.12 cm⁻¹. -1 1499.94 cm -1 The peak represents the skeletal vibration of the benzene ring, at 835.19 cm⁻¹. -1 The characteristic peak indicating para-substitution on the benzene ring is 1200.28 cm⁻¹. -1 1312.34 cm -1 These represent peaks at P=O and PC, respectively.

[0058] like Figure 2 As shown, the polyphosphate ester exhibits excellent thermal stability (527.67℃) and good flame retardant properties.

[0059] Example 2 This embodiment provides a polyphosphate compound and its preparation method, the preparation method comprising the following steps: Bisphenol F (52 g, 0.26 mol), phenyl methyl chlorophosphate (54.34 g, 0.28 mol), potassium carbonate (21.56 g, 0.16 mol), and sodium tetraphenylborate (0.09 g, 0.0003 mol) were added to a 250 mL three-necked flask equipped with a stirrer. The first stage reaction was carried out at 200 °C for 4.5 h under nitrogen protection. After the reaction of the raw materials was completed by liquid phase monitoring, the temperature was raised to 230 °C for the second stage reaction for 4.5 h. The nitrogen gas supply was stopped, and a vacuum operation was performed. The third stage reaction was carried out at 250 °C for 5 h to obtain a light yellow solid product, namely the polyphosphate compound.

[0060] Example 3 This embodiment provides a polyphosphate compound and its preparation method, the preparation method comprising the following steps: Bisphenol S (65 g, 0.26 mol), phenyl methyl chlorophosphate (56.81 g, 0.3 mol), potassium carbonate (17.97 g, 0.13 mol), and sodium tetraphenylborate (0.26 g, 0.0008 mol) were added to a 250 mL three-necked flask equipped with a stirrer. The first stage reaction was carried out at 160 °C for 6 h under nitrogen protection. After the reaction of the raw materials was completed by liquid phase monitoring, the temperature was raised to 200 °C for the second stage reaction for 6 h. The nitrogen gas supply was stopped, and a vacuum operation was performed. The third stage reaction was carried out at 230 °C for 7 h to obtain a light yellow solid product, namely the polyphosphate compound.

[0061] Example 4 This embodiment provides a polyphosphate compound and its preparation method, the preparation method comprising the following steps: Bisphenol A (60 g, 0.26 mol), phenyl methyl chlorophosphate (59.28 g, 0.31 mol), potassium carbonate (25.15 g, 0.18 mol), and sodium tetraphenylborate (0.17 g, 0.0005 mol) were added to a 250 mL three-necked flask equipped with a stirrer. The first stage reaction was carried out at 180 °C for 3 h under nitrogen protection. After the reaction of the raw materials was completed by liquid phase monitoring, the temperature was raised to 220 °C for the second stage reaction for 3 h. The nitrogen gas supply was stopped, and a vacuum operation was performed. The third stage reaction was carried out at 240 °C for 3 h to obtain a light yellow solid product, namely the polyphosphate compound.

[0062] Example 5 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of methyl chlorophosphate phenyl ester added in Example 1 is adjusted from 52.02 g to 64.22 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0063] Example 6 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of methyl chlorophosphate added in Example 1 is adjusted from 52.02 g to 59.28 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0064] Example 7 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of methyl chlorophosphate added in Example 1 is adjusted from 52.02 g to 56.8 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0065] Example 8 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that bisphenol A in Example 1 is replaced with an equimolar amount of hydroquinone. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0066] Example 9 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that methyl chlorophosphate phenyl ester in Example 1 is replaced with an equimolar amount of the compound methyl chlorophosphate methyl ester. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0067] Example 10 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that methyl chlorophenyl phosphate in Example 1 is replaced with an equimolar amount of the compound dimethyl phosphate. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0068] Example 11 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the sodium tetraphenylborate in Example 1 is replaced with an equimolar amount of sodium tetraphenylphosphonium tetraphenylborate. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0069] Example 12 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of sodium tetraphenylborate added in Example 1 is adjusted from 0.17 g to 0.35 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0070] Example 13 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of sodium tetraphenylborate added in Example 1 is adjusted from 0.17 g to 0.26 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0071] Example 14 This embodiment provides a polyphosphate compound and its preparation method. The only difference between this embodiment and Example 1 is that the amount of sodium tetraphenylborate added in Example 1 is adjusted from 0.17 g to 0.09 g. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0072] Comparative Example 1 This comparative example provides a polyphosphate compound and its preparation method. The only difference between this example and Example 1 is that sodium tetraphenylborate is not added in Example 1. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0073] Comparative Example 2 This comparative example provides a polyphosphate compound and its preparation method. The only difference between this example and Example 1 is that potassium carbonate is not added in Example 1, while the other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0074] Comparative Example 3 This comparative example provides a polyphosphate compound and its preparation method. The only difference between this example and Example 1 is that the potassium carbonate in Example 1 is replaced with an equimolar amount of triethylamine. All other raw materials, amounts added, and preparation methods are the same as in Example 1.

[0075] The polyphosphate compounds provided in Examples 1-14 and Comparative Examples 1-3 were subjected to performance tests, and the test methods / standards are as follows: (1) Viscosity: The viscosity was tested using an automatic viscometer IV2400 at 25°C; (2) Phosphorus content: The phosphorus content was determined by the gravimetric method using quinoline phosphomolybdate. (3) Weight average molecular weight: GPC was determined by gel chromatography.

[0076] The test results are shown in Table 1 below.

[0077] Table 1 According to the test results in Table 1: (1) As can be seen from Examples 1 to 14, the polyphosphate compound prepared by the preparation method provided by the present invention is a high molecular weight halogen-free phosphorus-containing polymer (weight average molecular weight of 60,000-150,000), with suitable viscosity (0.5-1 g / dL), high degree of polymerization, high phosphorus content (8-12%), and excellent flame retardant properties.

[0078] (2) As can be seen from Examples 1 and 5-7, the content of phosphate ester compounds in Example 5 was too high, which limited the polycondensation and reduced the viscosity, phosphorus content and weight-average molecular weight of the resulting polyphosphate ester compounds.

[0079] (3) Compared with Example 1 (Bisphenol A), the viscosity, phosphorus content and weight-average molecular weight of Example 8 (hydroquinone) were significantly reduced, indicating that the selection of bisphenol compounds as diphenol compounds in this invention can further improve the viscosity, phosphorus content and weight-average molecular weight of the obtained polyphosphate, thereby improving its flame retardant effect.

[0080] (4) By comparing Example 1 with Examples 9 and 10, it can be seen that compared with Example 1 (methyl chlorophosphate), the viscosity, phosphorus content and weight-average molecular weight of Examples 9 (methyl chlorophosphate) and 10 (diphenyl methyl phosphate) are significantly reduced. This shows that the selection of methyl chlorophosphate as a phosphate compound in this invention can further improve the viscosity, phosphorus content and weight-average molecular weight of the obtained polyphosphate, thereby improving its flame retardant effect.

[0081] (5) Compared with Example 1 (sodium tetraphenylborate), the viscosity, phosphorus content and weight-average molecular weight of Example 11 (sodium tetraphenylphosphonium tetraphenylborate) were significantly reduced, indicating that by optimizing the type of borate in this invention, the viscosity, phosphorus content and weight-average molecular weight of the obtained polyphosphate ester can be further improved, thereby improving its flame retardant effect.

[0082] (6) As can be seen from Examples 1 and 12-14, the content of borate in Example 12 is too high, which triggers chain termination reaction or excessive cross-linking. The viscosity and weight-average molecular weight of the resulting polyphosphate compound increase, which in turn affects its compatibility and processing performance in practical applications.

[0083] (7) By comparing Example 1 with Comparative Examples 1-3, it can be seen that the present invention can obtain polyphosphate compounds with excellent flame retardant effect by using carbonate and phosphate as composite catalysts. However, when only carbonate (Comparative Example 1) or borate (Comparative Example 2) or other alkaline salts (Comparative Example 3) are added, the viscosity, phosphorus content and weight-average molecular weight of the obtained polyphosphate compounds are significantly reduced, and the excellent flame retardant effect of the present invention cannot be achieved.

[0084] In summary, this invention utilizes a specific preparation method with carbonates and borates as composite catalysts and diphenolic compounds and phosphate esters as raw materials to obtain polyphosphate ester compounds with excellent flame retardant effects. Furthermore, by optimizing the types and contents of specific raw materials, polyphosphate ester compounds with more suitable viscosity (0.65-0.8 g / dL) and weight-average molecular weight (90,000-110,000) and higher phosphorus content (10-11%) can be obtained, further improving the flame retardant effect and processing performance of the obtained polyphosphate ester compounds.

[0085] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a polyphosphate compound, characterized in that, The preparation method includes the following steps: The polyphosphate compound is obtained by reacting a diphenolic compound with a phosphate ester compound in the presence of carbonate and borate.

2. The method for preparing the polyphosphate compound according to claim 1, characterized in that, The diphenolic compound is selected from any one of bisphenol A, bisphenol F, bisphenol S, resorcinol, catechol, or hydroquinone.

3. The method for preparing the polyphosphate compound according to claim 1 or 2, characterized in that, The molar ratio of the phosphate ester compound to the diphenol compound is (1.0-1.2):1; Preferably, the phosphate ester compound has the structure shown in Formula I: Formula I; Wherein, R1 is selected from any one of substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C6-C18 aryl, or substituted or unsubstituted C4-C10 heteroaryl; R2 is selected from any one of substituted or unsubstituted C1-C8 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C12 aryl, and substituted or unsubstituted C3-C12 heteroaryl. R3 is selected from halogens or -OR4; R4 is selected from any one of substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C6-C18 aryl, or substituted or unsubstituted C4-C10 heteroaryl; The substituent group is selected from any one of C1-C3 alkyl groups.

4. The method for preparing the polyphosphate compound according to claim 3, characterized in that, R1 is selected from any one of C1-C3 alkyl and C6-C12 aryl; R2 is selected from any one of C1-C6 alkyl, C3-C6 cycloalkyl, C6-C12 aryl, and C3-C12 heteroaryl; R4 is selected from any one of C1-C3 alkyl and C6-C12 aryl; Preferably, the phosphate ester compound includes any one or a combination of at least two of phenyl methyl chlorophosphate, methyl methyl chlorophosphate, diphenyl methyl phosphate, or dimethyl methylphosphonate.

5. The method for preparing the polyphosphate compound according to any one of claims 1-4, characterized in that, The molar ratio of the carbonate to the diphenolic compound is (0.5-0.7):1; Preferably, the carbonate includes any one or a combination of at least two of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, or potassium bicarbonate, and more preferably potassium carbonate.

6. The method for preparing the polyphosphate compound according to any one of claims 1-5, characterized in that, The molar ratio of the borate to the diphenol compound is (0.001-0.003):1; Preferably, the borate includes tetraphenylborate and / or tetraphenylphosphonium tetraphenylborate, more preferably tetraphenylborate; Preferably, the tetraphenylborate comprises any one or a combination of at least two of sodium tetraphenylborate, potassium tetraphenylborate, or ammonium tetraphenylborate.

7. The method for preparing the polyphosphate compound according to any one of claims 1-6, characterized in that, The reaction was carried out under solvent-free conditions; Preferably, the reaction includes a first-stage reaction, a second-stage reaction, and a third-stage reaction; Preferably, the temperature of the first stage reaction is 160-200℃ and the time is 3-6 h; Preferably, the temperature of the second stage reaction is 200-230℃, and the time is 3-6 h; Preferably, the temperature of the third stage reaction is 230-250℃, and the time is 3-7 h; Preferably, both the first-stage reaction and the second-stage reaction are carried out in a protective gas atmosphere; Preferably, the protective gas includes any one or a combination of at least two of argon, nitrogen, or helium; Preferably, the third-stage reaction is carried out under vacuum conditions.

8. The method for preparing the polyphosphate compound according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: The diphenolic compound, phosphate ester compound, carbonate and borate are mixed and subjected to a first-stage reaction at 160-200℃ for 3-6 h under a protective gas atmosphere. The temperature is then raised to 200-230℃ for a second-stage reaction for 3-6 h. The protective gas is then stopped, a vacuum operation is performed, and a third-stage reaction is carried out at 230-250℃ for 3-7 h to obtain the polyphosphate ester compound.

9. A polyphosphate compound, characterized in that, The polyphosphate compound is prepared by the method for preparing polyphosphate compounds according to any one of claims 1-8; Preferably, the weight-average molecular weight of the polyphosphate compound is 60,000-150,000, more preferably 70,000-130,000, and even more preferably 90,000-110,000; Preferably, the viscosity of the polyphosphate compound is 0.5-1 g / dL, more preferably 0.55-0.95 g / dL, and even more preferably 0.65-0.8 g / dL; Preferably, the phosphorus content of the polyphosphate compound is 8-12%, more preferably 9-11%, and even more preferably 10-11%.

10. A phosphate ester flame retardant, characterized in that, The phosphate flame retardant includes a polyphosphate compound prepared by the method described in any one of claims 1-8, or a polyphosphate compound as described in claim 9.

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