A three-in-one cyclophosphazene-based flame retardant and its preparation method and application

Abstract

The present invention discloses a three-in-one cyclophosphazene-based flame retardant, belonging to the field of chemical materials technology. The structural formula of the flame retardant is as follows: #imgabs0#, #imgabs1#; wherein, the preparation method of the flame retardant comprises the following specific steps: after uniformly mixing a pentaerythritol solution and a melamine solution, an acid-binding agent and a hexachlorocyclotriphosphazene solution are sequentially added dropwise to react, and a precipitate is obtained after the reaction is completed, which is a three-in-one cyclophosphazene-based flame retardant. The present invention is a molecular design integrating "gas source, carbon source, acid source", wherein the presence of a benzene ring, nitrogen element, and carbon element is conducive to improving the flame retardant efficiency of the cyclotriphosphazene, and helps to improve the efficiency of the elemental collection of phosphazene derivatives in the combustion process of polymer materials, thereby achieving the purpose of condensed phase-gas phase dual flame retardancy.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical materials, and in particular relates to a three-in-one cyclophosphazene-based flame retardant and a preparation method and application thereof. Background Art

[0002] With the development of society and the improvement of industrial level, all walks of life pay more and more attention to the combustion safety of building materials and products, so flame retardants are emerging in the market. However, the flame retardants in the existing technology have problems such as instability, excessive dosage and unsafe.

[0003] Currently, achieving the desired flame retardant effect typically requires the addition of a relatively large amount of flame retardant, which significantly reduces the mechanical properties of the material. Furthermore, due to the tendency of flame retardants to aggregate within the material matrix and their poor compatibility with the matrix, these agents can be unevenly dispersed, easily migrate to the matrix surface, and exhibit poor thermal stability, all of which negatively impact the flame retardant properties of the material.

[0004] Phosphazenes are a class of compounds composed of alternating phosphorus and nitrogen elements with a stable phosphorus-nitrogen skeleton structure. Their unique phosphorus-nitrogen hybrid structure and high phosphorus and nitrogen content give them excellent thermal stability and flame retardancy. Phosphazenes are considered second-generation phosphorus-nitrogen intumescent flame retardants due to their advantages such as being halogen-free, producing low smoke during combustion, high flame retardant efficiency, and not producing toxic or corrosive gases. Since their synthesis, phosphazene compounds have undergone over a century of research and development. In the United States, they are used in a wide range of fields, including military materials. They are also being researched and applied in various fields in China, with particular emphasis on flame retardancy. However, the domestic market for phosphazene flame retardants is limited, primarily due to issues with flame retardant efficiency and element synergy with existing nitrogen-phosphorus flame retardants.

[0005] Therefore, it is an urgent problem for those skilled in the art to provide a stable, safe and efficient phosphorus-based flame retardant that does not require excessive addition. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a three-in-one cyclophosphazene-based flame retardant and a preparation method and application thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A three-in-one cyclophosphazene-based flame retardant, wherein the structure of the flame retardant is selected from any one of the following:

[0009] 、 .

[0010] According to the above-mentioned preparation method of a three-in-one cyclophosphazene-based flame retardant, the following specific steps are included:

[0011] After the pentaerythritol solution and the melamine solution are uniformly mixed, an acid-binding agent and a hexachlorocyclotriphosphazene solution are sequentially added dropwise to react. After the reaction is completed, a precipitate is obtained, which is a three-in-one cyclophosphazene-based flame retardant.

[0012] Preferably, the molar ratio of the hexachlorocyclotriphosphazene, the melamine, the pentaerythritol and the acid binding agent is 2:2-4:1:12.

[0013] Preferably, the molar ratio of the hexachlorocyclotriphosphazene, the melamine, the pentaerythritol and the acid binding agent is 2:4:1:12.

[0014] Preferably, the molar ratio of the hexachlorocyclotriphosphazene, the melamine, the pentaerythritol and the acid binding agent is 1:1:2:6.

[0015] Preferably, the acid binding agent is triethylamine.

[0016] Preferably, the solvents of the pentaerythritol solution, the melamine solution and the hexachlorocyclotriphosphazene solution are N,N-dimethylformamide or dimethyl sulfoxide, and the added amount is sufficient to ensure that the hexachlorocyclotriphosphazene, the melamine and the pentaerythritol can be dissolved.

[0017] Preferably, the reaction temperature is 25-80° C. and the reaction time is 12-48 h.

[0018] Preferably, the reaction is carried out under a nitrogen atmosphere.

[0019] Preferably, the process route of the preparation method is:

[0020]

[0021] or

[0022] .

[0023] The flame retardant prepared according to the above-mentioned preparation method or the use of the above-mentioned flame retardant in the preparation of epoxy resin.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses a substance containing a triazine ring and a high carbon content hydroxyl structure to undergo a nucleophilic substitution reaction with hexachlorocyclotriphosphazene. Through a molecular design that integrates "gas source-carbon source-acid source", the presence of a benzene ring, nitrogen elements and carbon elements is beneficial to improving the flame retardant efficiency of cyclotriphosphazene, and helps to improve the efficiency of element collection of phosphazene derivatives in the combustion process of polymer materials, thereby achieving the purpose of condensed phase-gas phase dual flame retardancy;

[0026] (2) The product prepared by the present invention is used as a flame retardant additive for polymer materials, and has the properties of good heat resistance, good synergistic effect, rich content of flame retardant elements, and high flame retardant efficiency;

[0027] (3) The preparation method and post-processing method of the present invention are simple, the reagents used are non-toxic and have no potential environmental pollution risks, and the raw materials do not need to be pretreated, which greatly reduces economic and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 This is the infrared spectrum of the flame retardant of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing a three-in-one cyclophosphazene-based flame retardant comprises the following specific steps:

[0033] (1) 3.4766g hexachlorocyclotriphosphazene and 0.68075g pentaerythritol were completely dissolved in 30ml N,N-dimethylformamide respectively, and 2.5224g melamine was fully dispersed and dissolved in 140ml N,N-dimethylformamide. The dissolution was carried out under ultrasonic conditions with a power of 100W. Then, the pentaerythritol solution and the melamine solution were evenly mixed and 8ml triethylamine solution was added dropwise. The triethylamine solution was dripped at a rate of about 1 drop per second and the addition was completed in about 3 minutes. After the addition was completed, the reaction system was placed under a nitrogen atmosphere and the hexachlorocyclotriphosphazene solution was slowly added dropwise. The hexachlorocyclotriphosphazene was dripped at a rate of 1-2 drops per second and the addition was completed within 10 minutes. After the addition was completed, gas sealing measures were taken to allow the reaction to proceed under nitrogen protection at 25°C for 48 hours. The entire reaction process was carried out under ultrasonic conditions with a power of 100W. During the reaction, it was ensured that there was sufficient clean water in the ultrasonic instrument.

[0034] (2) After the reaction is completed, cool and stand, filter under reduced pressure, collect the solid matter and use anhydrous ethanol three times to obtain an off-white solid, which is dried at 70 ° C in vacuum to obtain a trinity cyclophosphazene-based flame retardant with the structure The yield is 90% and the purity is about 85%.

[0035] Example 2

[0036] A method for preparing a three-in-one cyclophosphazene-based flame retardant comprises the following specific steps:

[0037] (1) 3.4766g hexachlorocyclotriphosphazene and 2.723g pentaerythritol were completely dissolved in 30ml and 90ml N,N-dimethylformamide respectively, and 1.2612g melamine was fully dispersed and dissolved in 70ml N,N-dimethylformamide. The dissolution was carried out under ultrasonic conditions with a power of 100W. Then, the pentaerythritol solution and the melamine solution were mixed evenly and 8ml triethylamine solution was added dropwise. The triethylamine solution was dripped at a rate of about 1 drop per second and the addition was completed in about 3 minutes. After the addition was completed, the reaction system was placed under a nitrogen atmosphere and the hexachlorocyclotriphosphazene solution was slowly added dropwise. The hexachlorocyclotriphosphazene was dripped at a rate of 1-2 drops per second and the addition was completed within 10 minutes. After the addition was completed, gas sealing measures were taken to allow the reaction to proceed under nitrogen protection at 25°C for 48 hours. The entire reaction process was carried out under ultrasonic conditions with a power of 100W. During the reaction, it was ensured that there was sufficient clean water in the ultrasonic instrument.

[0038] (2) After the reaction is completed, cool and stand, filter under reduced pressure, collect the solid matter and use anhydrous ethanol twice to obtain an off-white solid, which is dried at 70°C in a vacuum to obtain a trinity cyclophosphazene-based flame retardant with the structure: The yield is 40% and the purity is about 85%.

[0039] Example 3

[0040] A method for preparing a three-in-one cyclophosphazene-based flame retardant comprises the following specific steps:

[0041] (1) 3.4766g hexachlorocyclotriphosphazene and 0.68075g pentaerythritol were completely dissolved in 30ml dimethyl sulfoxide respectively, and 2.5224g melamine was fully dispersed and dissolved in 100ml dimethyl sulfoxide. The dissolution was carried out under ultrasonic conditions with a power of 100W. Then, the pentaerythritol solution and the melamine solution were mixed evenly and 8ml triethylamine solution was added dropwise. The triethylamine solution was dripped at a rate of about 1 drop per second and the addition was completed in about 3 minutes. After the addition was completed, the hexachlorocyclotriphosphazene solution was slowly added dropwise to the reaction system under a nitrogen atmosphere. The hexachlorocyclotriphosphazene was dripped at a rate of 1-2 drops per second and the addition was completed within 10 minutes. After the addition was completed, gas sealing measures were taken to allow the reaction to proceed under nitrogen protection at 25°C for 48 hours. The entire reaction process was carried out under ultrasonic conditions with a power of 100W. During the reaction, it was ensured that there was sufficient clean water in the ultrasonic instrument.

[0042] (2) After the reaction is completed, cool and stand, filter under reduced pressure, collect the solid matter and use anhydrous ethanol three times to obtain an off-white solid, which is dried at 70 ° C in vacuum to obtain a trinity cyclophosphazene-based flame retardant with the structure The yield is 10% and the purity is about 85%.

[0043] Example 4

[0044] A method for preparing a three-in-one cyclophosphazene-based flame retardant comprises the following specific steps:

[0045] (1) 3.4766g hexachlorocyclotriphosphazene and 0.68075g pentaerythritol were completely dissolved in 30ml N,N-dimethylformamide respectively, and 2.5224g melamine was fully dispersed and dissolved in 140ml N,N-dimethylformamide. The dissolution was carried out under ultrasonic conditions with a power of 100W. Then, the pentaerythritol solution and the melamine solution were evenly mixed and 8ml triethylamine solution was added dropwise. The triethylamine solution was dripped at a rate of about 1 drop per second and the addition was completed in about 3 minutes. After the addition was completed, the reaction system was placed under a nitrogen atmosphere and the hexachlorocyclotriphosphazene solution was slowly added dropwise. The hexachlorocyclotriphosphazene was dripped at a rate of 1-2 drops per second and the addition was completed within 10 minutes. After the addition was completed, gas sealing measures were taken to allow the reaction to proceed under nitrogen protection at 25°C for 12 hours. The entire reaction process was carried out under ultrasonic conditions with a power of 100W. During the reaction, it was ensured that there was sufficient clean water in the ultrasonic instrument.

[0046] (2) After the reaction is completed, cool and stand, filter under reduced pressure, collect the solid matter and use anhydrous ethanol three times to obtain an off-white solid, which is dried at 70 ° C in vacuum to obtain a trinity cyclophosphazene-based flame retardant with the structure The yield is 90% and the purity is about 85%.

[0047] like Figure 1, which is the infrared spectra of the flame retardants prepared in Examples 1 and 2. It can be seen from the figure that the relevant compounds were successfully prepared.

[0048] Application Example 1

[0049] Preparation of epoxy resin composite materials:

[0050] The flame retardants prepared in Examples 1 and 2 were added to the epoxy resin at a ratio of 1 wt %, wherein 30 g of epoxy resin, 0.42 g of flame retardant, and 12 g of curing agent DDM were uniformly mixed, poured into a mold and placed in an oven. The mixture was cured at 100° C. for 3 h and at 160° C. for 1 h. After curing, all samples were cooled to room temperature and demolded to obtain epoxy composite materials, which were then subjected to a combustion test.

[0051] The results of the combustion test are shown in Table 1. The test method is as follows: according to ASTM D3801-2006, a vertical combustion test was conducted on a vertical combustion tester to test the flammability of epoxy composite materials with a size of 100×150×3 mm; according to ASTM D2863, the limiting oxygen index (LOI) test of the epoxy composite materials was conducted on an oxygen index analyzer with a sample test size of 100×150×3 mm.

[0052] The UL-94 standard is a test method standard for material combustion performance developed by Underwriters Laboratories of the United States. It is used to evaluate the ability of a material to extinguish after being ignited. It stipulates that the flame retardancy level of plastics increases step by step from HB, V-2, V-1 to V-0. Specifically:

[0053] HB: For samples with a thickness of 3-13mm, the burning speed is required to be less than 40mm / min; for samples with a thickness of less than 3mm, the burning speed is required to be less than 70mm / min, or the fire is extinguished before the 100mm mark.

[0054] V-2: After two 10-second combustion tests on the sample, the flame goes out within 10-30 seconds, and the burning material may fall off;

[0055] V-1: After two 10-second combustion tests on the sample, the flame shall be extinguished within 10-30 seconds, and no burning objects shall fall;

[0056] V-0: After two 10-second combustion tests on the sample, the flame goes out within 10 seconds and no burning objects fall off;

[0057] Table 1 Vertical combustion data of epoxy composite materials

[0058]

[0059] It can be seen from the data in Table 1 that the flame retardant properties of the epoxy composite materials prepared using the flame retardants in Examples 1 and 2 have reached V-0 level, and the oxygen index of the epoxy composite materials is 28.5% and 27.1%.

[0060] Comparative Example 1

[0061] Materials selected from: Wang Yuchong. Synthesis of melamine-modified polyaminocyclotriphosphazene and its flame retardant effect on epoxy resin[D]. Qingdao University of Science and Technology, 2015.

[0062] The preparation method is:

[0063] Add 10 g (0.0287 mol) of hexachlorocyclotriphosphazene, 6.95 g (0.0574 mol) of melamine, 15.67 g (0.1722 mol) of triethylamine, and 200 mL of chlorobenzene to a reaction flask. Under nitrogen, heat to 70-130°C and react for 8-20 hours. Then cool in a salt ice bath. Ammoniating: After the temperature of the above materials cools to -5-5°C, introduce ammonia gas at a constant rate while stirring and react for 8-30 hours. Filter and air-dry the filter cake to obtain a white powdery solid—a mixture of melamine-modified aminocyclotriphosphazene and the by-product water-soluble ammonium salt (triethylamine hydrochloride and ammonium chloride).

[0064] Polycondensation: The mixture of the melamine-modified aminocyclotriphosphazene and the ammonium salt is placed in a drying oven and subjected to polycondensation at 170-190°C for 10-60 minutes. The mixture is then taken out and allowed to cool to room temperature in air. Separation of the polycondensation product from the ammonium salt: The polycondensation mixture obtained above is dispersed in a certain amount of deionized water, stirred at room temperature for 10 minutes, filtered, and the filter cake is washed three times with a small amount of deionized water and dried to a constant weight to obtain melamine-modified polyaminocyclotriphosphazene (MPHACTPA).

[0065] The specific process route is as follows:

[0066] ;

[0067] The flame retardant obtained in Comparative Example 1 was used to prepare an epoxy resin composite material: 90 g of epoxy resin (E-44), 13.5 g of modified fatty amine DG731 and a certain amount of flame retardant were mixed uniformly, then placed in a mold and cured at room temperature for 0.5 h, then transferred to a tablet press and compression molded at room temperature to form a 100 mm × 100 mm × 3.2 mm plate. The plate was then cut into strips of standard size for flame retardant performance testing. The effect of the addition amount of MPHACTPA-1 on the flame retardant E-44 / DG731 is shown in Table 2.

[0068] Table 2 Vertical combustion data of epoxy composite materials

[0069]

[0070] As can be seen from the above table, compared with Examples 1 and 2 and Comparative Example 1, when the mass fraction of the flame retardant in Comparative Example 1 is 20wt%, the oxygen index of Comparative Example 1 does not exceed the relevant indicators of Examples 1 and 2. It can be seen that the product obtained by the technical solution of the present invention has better combustion index performance in epoxy resin.

[0071] Comparative Example 2

[0072] Materials selected from: Kang Tao, Juan Li, Liang Xu, et al. A novel phosphazenecyclomatrix network polymer: Design, synthesis and application in flameretardant polylactide[J]. Polymer Degradation and Stability. 2011, 96(7):1248-1254.

[0073] The preparation method is as follows:

[0074] HCCP (139.06 g, 0.40 mol), PER (122.54 g, 0.60 mol), sodium hydroxide (96 g, 2.4 mol) and 300 ml of tetrahydrofuran were placed in a 1000 ml flask and connected to a drying tube. The mixture was refluxed under N2 for 6 h, then cooled to room temperature and precipitated with a 10-fold excess of water. The solid was filtered and washed with water and acetone. The white product PCPP was dried in vacuo at 80°C to constant weight (yield 92.7%).

[0075] The specific process route is as follows:

[0076] ;

[0077] Polylactic acid composites were prepared using the flame retardant obtained in Comparative Example 2: All composite materials were prepared in a Brabender mixer at a temperature of 180°C and a roller speed of 50 rpm for 8 minutes. The mixed samples were transferred to a mold, preheated at 185°C for 5 minutes, and then pressurized at 10 MPa. While maintaining the pressure, the samples were cooled to room temperature to obtain composite sheets for further measurements. Before mixing, all materials were dried in a vacuum oven at 80°C for at least 12 hours. The LOI and UL-94 test results of the PLA composites are shown in Table 3.

[0078] Table 3 LOI and UL-94 test results of PLA composites

[0079]

[0080] As can be seen from the above table, compared with Examples 1 and 2 and Comparative Example 2, when the mass fraction of the flame retardant in Comparative Example 2 is 20wt%, the oxygen index of Comparative Example 2 does not exceed the relevant indicators of Examples 1 and 2. It can be seen that the product obtained by the technical solution of the present invention has better combustion index performance in epoxy resin.

[0081] The various embodiments are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to in detail.

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A trinity cyclophosphazene-based flame retardant, characterized in that: The structure of the flame retardant is selected from any one of the following: 、 。 2. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 1, characterized in that: The specific steps include: After the pentaerythritol solution and the melamine solution are uniformly mixed, an acid-binding agent and a hexachlorocyclotriphosphazene solution are sequentially added dropwise to react. After the reaction is completed, a precipitate is obtained, which is a three-in-one cyclophosphazene-based flame retardant.

3. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 2, wherein: The molar ratio of the hexachlorocyclotriphosphazene, the melamine, the pentaerythritol and the acid binding agent is 2:2-4:1:

12.

4. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 2, wherein: The acid binding agent is triethylamine.

5. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 2, characterized in that: The solvents of the pentaerythritol solution, the melamine solution and the hexachlorocyclotriphosphazene solution are N,N-dimethylformamide or dimethyl sulfoxide.

6. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 2, characterized in that: The reaction temperature is 25-80° C. and the reaction time is 12-48 hours.

7. The method for preparing a three-in-one cyclophosphazene-based flame retardant according to claim 2, characterized in that: The reaction was carried out under nitrogen atmosphere.

8. Use of the flame retardant according to claim 1 or the flame retardant prepared by the preparation method according to any one of claims 2 to 7 in the preparation of epoxy resin.

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