Triazinyl phosphazene macromolecular flame retardant as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of flame retardants, and particularly relates to a triazinyl phosphazene macromolecular flame retardant as well as a preparation method and application thereof. The structure of the flame retardant is shown as a formula I. The preparation method disclosed by the invention has the advantages of simplicity, easiness in operation, no need of special reaction equipment in the preparation process, simple process, high product purity, easiness in industrialization and the like. The invention provides a new choice for flame retardance of the PC resin.

Description

Technical Field

[0001] This application belongs to the field of flame retardant technology, specifically relating to a triazine phosphazene macromolecular flame retardant, its preparation method, and its application. Background Technology

[0002] Polycarbonate (PC), a commonly used engineering plastic, possesses excellent heat resistance, impact resistance, and flame retardancy, and is widely used in electronics, healthcare, transportation, construction, and agriculture. While the aromatic groups present in the main chain of PC provide some flame retardancy, they still cannot meet the increasingly stringent market demands for flame-retardant products.

[0003] Adding flame retardants is a simple, quick, and efficient way to improve flame retardancy. Flame retardants are divided into halogenated and halogen-free flame retardants, with halogen-free flame retardants gradually becoming a leading force in the flame retardant field due to their environmental friendliness and low toxicity. Polyphosphazene covalent triazine frameworks, as a type of halogen-free flame retardant, combine the advantages of phosphazene and triazine ring groups to provide excellent flame retardant properties. However, current research on polyphosphazene covalent triazine frameworks is limited, and their synthesis methods have certain limitations. For example, CN119143998A discloses a polyphosphazene covalent triazine flame retardant and its preparation method and application, which involves introducing a triazine ring first and then a phosphazene ring. This synthesis method cannot ensure a uniform distribution of the phosphazene and triazine rings, resulting in significant randomness and thus affecting the product's flame retardant performance. Summary of the Invention

[0004] To address the issue of uneven distribution of phosphazene and triazine rings in products, thereby improving flame retardancy, and to resolve the problem of excessive flame retardant usage in PC, the present invention aims to provide a triazine-based phosphazene macromolecular flame retardant.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, this application provides a triazine-based phosphazene macromolecular flame retardant, the structure of which is shown in Formula I:

[0007]

[0008] in, For repeating units.

[0009] This invention, from a molecular design perspective, first synthesizes a benzonitrile derivative, and then generates the target product through a cyclization reaction of the benzonitrile derivative. This synthetic method generates a covalent triazine framework, ensuring a uniform distribution of triazine rings around the phosphazene ring in the target product. Compared with existing technologies, this minimizes incomplete amino reactions caused by excessive steric hindrance and increases the uniformity of group distribution in the product.

[0010] Secondly, this application provides a method for preparing the above-mentioned triazine phosphazene macromolecular flame retardant, comprising the following steps:

[0011] (1) Hexachlorocyclotriphosphazene, p-aminobenzonitrile and acid-coating agent were added to solvent 1 under an inert atmosphere and stirred; reaction 1 was carried out by distillation of crude product and recrystallization to obtain product 1;

[0012] (2) Add product 1 to solvent 2 under an inert atmosphere and stir; add catalyst and react 2; filter and wash to obtain product 2.

[0013] In the above reaction process, hexachlorocyclotriphosphazene can provide phosphazene rings for the product, p-aminobenzonitrile can provide triazine rings, and the acid-coating agent can bind to the hydrochloric acid byproduct that appears during the reaction, ensuring that the reaction proceeds efficiently and continuously.

[0014] As a specific embodiment of this application, the acid-applying agent in step (1) includes at least one of triethylamine, pyridine, sodium carbonate and potassium carbonate;

[0015] As a specific embodiment of this application, solvent 1 in step (1) includes at least one of chlorobenzene, dioxane, trichloromethane, and dichloromethane.

[0016] As a specific embodiment of this application, the molar ratio of hexachlorocyclotriphosphazene, p-aminobenzonitrile and acid-coating agent in step (1) is 0.5-1.5:5-7:5-7; preferably 0.9-1.1:5.9-6.1:6-6.5.

[0017] The molar ratio specified in this invention ensures that the reaction proceeds as completely as possible and reduces raw material waste. Excessive hexachlorocyclotriphosphazene will result in unreacted chlorine residues in the product, while excessive p-aminobenzonitrile will affect the purity of the product after ethanol recrystallization.

[0018] In a specific embodiment of this application, the recrystallization is performed using ethanol recrystallization.

[0019] Recrystallization improves the purity of the product, thereby enhancing the performance of the flame retardant.

[0020] As a specific embodiment of this application, solvent 2 in step (2) includes at least one of chlorobenzene, dioxane, chloroform, and dichloromethane;

[0021] As a specific embodiment of this application, the catalyst in step (2) includes at least one of trifluoromethanesulfonic acid, anhydrous aluminum trichloride, and anhydrous ferric trichloride.

[0022] In a specific implementation of this application, the purification in step 2 is carried out using Soxhlet extraction.

[0023] Soxhlet extraction improves the purity of the product, thereby enhancing the performance of flame retardants.

[0024] As a specific embodiment of this application, the Soxhlet extraction solvent includes at least one of chlorobenzene, dioxane, chloroform, and dichloromethane.

[0025] Secondly, this application provides the use of the above-mentioned triazine phosphazene macromolecular flame retardant or the triazine phosphazene macromolecular flame retardant prepared by the above method as a flame retardant for resins or plastics.

[0026] As a specific embodiment of this application, it includes dispersing into PC resin via an extruder.

[0027] Intentional effects of the present invention

[0028] 1. This invention, from a molecular design perspective, first synthesizes a benzonitrile derivative, and then generates the target product through a cyclization reaction of the benzonitrile derivative. This synthetic method can generate a covalent triazine framework, ensuring that the triazine ring is uniformly distributed around the phosphazene ring in the target product. Compared with existing technologies, this minimizes the incomplete amino reaction caused by excessive steric hindrance and increases the uniformity of group distribution in the product.

[0029] 2. This invention has the advantages of requiring no special reaction equipment, having a simple process, producing high-purity products, and being easy to industrialize.

[0030] 3. This invention provides a new option for flame retardant PC resin. Detailed Implementation

[0031] Example 1

[0032] A method for preparing a triazine-based phosphazene macromolecular flame retardant includes the following steps:

[0033] Under nitrogen atmosphere, 0.05 mol of hexachlorocyclotriphosphazene, 0.7 mol of p-aminobenzonitrile, and 0.5 mol of acid-binding agent were added to a dry round-bottom flask. 100 mL of chlorobenzene was added, and the mixture was stirred for 0.5 h to ensure uniform dispersion. The mixture was heated to reflux temperature and reacted for 24 h. The crude product was then distilled under reduced pressure and recrystallized with anhydrous ethanol to obtain the target product, product 1.

[0034]

[0035] Under nitrogen atmosphere, 0.10 mol of product 1 was added to a dry round-bottom flask, followed by the addition of 400 mL of chloroform, stirring, and cooling to 0°C. 0.10 mol each of the catalyst trifluoromethanesulfonic acid and anhydrous aluminum trichloride were slowly added dropwise. After the addition was complete, the reaction continued for 2 hours, then the temperature was slowly raised to room temperature and the reaction proceeded for 24 hours. The product was filtered and washed three times with deionized water, ethanol, and tetrahydrofuran. After purification using Soxhlet extraction, the product was dried to obtain product 2.

[0036]

[0037] Example 2

[0038] A method for preparing a triazine-based phosphazene macromolecular flame retardant includes the following steps:

[0039] Under nitrogen atmosphere, 0.15 mol of hexachlorocyclotriphosphazene, 0.5 mol of p-aminobenzonitrile, and 0.7 mol of pyridine (an acid-binding agent) were added to a dry round-bottom flask. 100 mL of chlorobenzene was added, and the mixture was stirred for 0.5 h to ensure uniform dispersion. The mixture was heated to reflux temperature and reacted for 24 h. The crude product was then distilled under reduced pressure, and recrystallized from ethanol to obtain the target product, product 1.

[0040] Under nitrogen atmosphere, 0.10 mol of product 1 was added to a dry round-bottom flask, followed by the addition of 400 mL of chloroform, stirring, and cooling to 0°C. 0.10 mol each of anhydrous aluminum trichloride and trifluoromethanesulfonic acid were slowly added dropwise. After the addition was complete, the reaction continued for 2 hours, followed by a slow increase to room temperature and a reaction time of 24 hours. The product was filtered and washed three times with deionized water, ethanol, and tetrahydrofuran. After purification using Soxhlet extraction, the product was dried to obtain product 2.

[0041] Example 3

[0042] A method for preparing a triazine-based phosphazene macromolecular flame retardant includes the following steps:

[0043] Under nitrogen atmosphere, 0.10 mol of hexachlorocyclotriphosphazene, 0.61 mol of p-aminobenzonitrile, and 0.65 mol of triethylamine (an acid-binding agent) were added to a dry round-bottom flask. 100 mL of chlorobenzene was added, and the mixture was stirred for 0.5 h to ensure uniform dispersion. The mixture was heated to reflux temperature and reacted for 24 h. The crude product was then distilled under reduced pressure, and recrystallized from ethanol to obtain the target product, product 1.

[0044] Under nitrogen atmosphere, 0.10 mol of product 1 was added to a dry round-bottom flask, followed by the addition of 400 mL of chloroform, stirring, and cooling to 0°C. 0.10 mol each of the catalyst trifluoromethanesulfonic acid and anhydrous aluminum trichloride were slowly added dropwise. After the addition was complete, the reaction continued for 2 hours, then the temperature was slowly raised to room temperature and the reaction proceeded for 24 hours. The product was filtered and washed three times with deionized water, ethanol, and tetrahydrofuran. After purification using Soxhlet extraction, the product was dried to obtain product 2.

[0045] Example 4

[0046] A method for preparing a triazine-based phosphazene macromolecular flame retardant includes the following steps:

[0047] Under nitrogen atmosphere, 0.10 mol of hexachlorocyclotriphosphazene, 0.61 mol of p-aminobenzonitrile, and 0.65 mol of sodium carbonate (an acid-binding agent) were added to a dry round-bottom flask. 100 mL of dioxane was added, and the mixture was stirred for 0.5 h to ensure uniform dispersion. The mixture was heated to reflux temperature and reacted for 24 h. The crude product was then distilled under reduced pressure, and recrystallized from ethanol to obtain the target product, product 1.

[0048] Under nitrogen atmosphere, 0.10 mol of product 1 was added to a dry round-bottom flask, followed by 400 mL of chloroform, stirring, and cooling to 0°C. 0.08 mol of anhydrous ferric chloride catalyst and trifluoromethanesulfonic acid were slowly added dropwise. After the addition was complete, the reaction continued for 2 h, then the temperature was slowly raised to room temperature and the reaction proceeded for 24 h. The product was filtered and washed three times with deionized water, ethanol, and tetrahydrofuran. After purification using Soxhlet extraction, the product was dried to obtain product 2.

[0049] Comparative Example 1

[0050] Compared to Example 3, the acid-binding agent triethylamine was not added.

[0051] Comparative Example 2

[0052] Compared to Example 3, 0.03 mol of hexachlorocyclotriphosphazene, 0.60 mol of p-aminobenzonitrile, and 0.35 mol of triethylamine, an acid-binding agent, were added to a dry round-bottom flask under a nitrogen atmosphere.

[0053] Comparative Example 3

[0054] Compared to Example 3, 0.10 mol of hexachlorocyclotriphosphazene, 0.30 mol of p-aminobenzonitrile, and 0.35 mol of triethylamine, an acid-binding agent, were added to a dry round-bottom flask under a nitrogen atmosphere.

[0055] Table 1: Yield analysis of flame retardants in Examples 1-4 and Comparative Examples 1-5

[0056] Product 1 yield Product 2 yield Example 1 86.7％ 88.3％ Example 2 90.6％ 92.3％ Example 3 93.5％ 94.3％ Example 4 92.9％ 90.3％ Comparative Example 1 70.2％ 72.8％ Comparative Example 2 70.3％ 71.8％ Comparative Example 3 72.3％ 72.9％

[0057] Implementation Results Example

[0058] The comprehensive fire resistance of this patented product was evaluated by combining oxygen index and flame retardant properties. The halogen-free flame retardant obtained in the synthesis experiment was dispersed into PC resin using an extruder, and the injection-molded samples were placed in an environment of 23℃ and 50% humidity for 48 hours before testing. The raw material ratios and experimental results are shown in Table 2.

[0059] Table 2: Formulation and Application Performance of Flame Retardants in Examples 1-4 and Comparative Examples 1-5 in PC Flame Retardancy

[0060]

[0061]

[0062] As can be seen from the table above, by introducing a covalent triazine framework structure, the product of this invention enables PC to achieve a V-0 flame retardant rating and a high oxygen index when the flame retardant addition amount is only 4%. This is due to the excellent carbon-forming structure and uniform distribution of the triazine ring and phosphazene ring in the product.

[0063] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A triazine-based phosphazene macromolecular flame retardant, characterized in that, The structure of the flame retardant is shown in Formula I: in, For repeating units.

2. A method for preparing the triazine phosphazene macromolecular flame retardant according to claim 1, characterized in that, Includes the following steps: (1) Hexachlorocyclotriphosphazene, p-aminobenzonitrile and acid-coating agent were added to solvent 1 under an inert atmosphere and stirred; reaction 1 was carried out by distillation of crude product and recrystallization to obtain product 1; (2) Add product 1 to solvent 2 under an inert atmosphere and stir; add catalyst and react 2; filter and wash to obtain product 2.

3. The method for preparing the triazine-based phosphazene macromolecular flame retardant according to claim 2, characterized in that, The acid-coating agent in step (1) includes at least one of triethylamine, pyridine, sodium carbonate, and potassium carbonate; And / or, in step (1), solvent 1 includes at least one of chlorobenzene, dioxane, chloroform, and dichloromethane.

4. The method for preparing the triazine-based phosphazene macromolecular flame retardant according to claim 2, characterized in that, In step (1), the molar ratio of hexachlorocyclotriphosphazene, p-aminobenzonitrile and the acid-coating agent is 0.5-1.5:5-7:5-7; preferably 0.9-1.1:5.9-6.1:6-6.

5.

5. The method for preparing the triazine-based phosphazene macromolecular flame retardant according to claim 2, characterized in that, The recrystallization was performed using ethanol.

6. The method for preparing the triazine-based phosphazene macromolecular flame retardant according to claim 2, characterized in that, In step (2), solvent 2 includes at least one of chlorobenzene, dioxane, chloroform, and dichloromethane; And / or, the catalyst in step (2) includes at least one of trifluoromethanesulfonic acid, anhydrous aluminum trichloride, and anhydrous ferric trichloride.

7. The method for preparing the triazine-phosphazene macromolecular flame retardant according to any one of claims 2-6, characterized in that, In step 2, purification is performed using Soxhlet extraction.

8. The method for preparing the triazine-based phosphazene macromolecular flame retardant according to any one of claims 7, characterized in that, The Soxhlet extraction solvent includes at least one of chlorobenzene, dioxane, trichloromethane, and dichloromethane.

9. The application of the triazine phosphazene macromolecular flame retardant according to claim 1 or the triazine phosphazene macromolecular flame retardant prepared by the method according to any one of claims 2-8 as a flame retardant for resins or plastics.

10. The application according to claim 9, characterized in that, This includes dispersing it into PC resin via an extruder.

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