N, P and B integrated flame retardant as well as synthesis method and application thereof

Abstract

The invention provides an N, P and B integrated flame retardant as well as a synthesis method and application thereof, and belongs to the technical field of flame retardants. According to the flame retardant provided by the invention, three flame-retardant functions of nitrogen, phosphorus and boron are integrated in the same product, all the components have a synergistic effect in the combustion process, a glassy carbonized layer is formed, inert gas is released, meanwhile, smoke generation is inhibited, and the flame-retardant efficiency and the thermal stability of the material are improved. All chemical reactions are completed in the solid phase kettle through a one-pot reaction method, complex operation of a traditional multi-step process is avoided, the production process is remarkably simplified, and equipment investment and operation difficulty are reduced. Nitrogen protection is adopted in the reaction process, and generation of oxidation by-products is avoided; the final product is the halogen-free flame retardant, does not release toxic gas, and meets the environmental protection requirement. By optimizing the raw material ratio and reaction conditions, the synthetic reaction can be completed at a lower temperature, and the energy consumption is lower; and the product is solid powder and is easy to store and transport, so that the overall production cost is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and in particular to a N, P, B integrated flame retardant and a synthesis method and application thereof. Background Art

[0002] As an important additive for polymer materials, flame retardants are widely used in base materials such as plastics, coatings and wood. Their main function is to inhibit the spread of flames, reduce fire hazards and improve the safety of materials. According to their composition, flame retardants can be divided into two categories: halogen flame retardants and halogen-free flame retardants. Halogen flame retardants are mainly chlorine-containing or bromine-containing compounds, which have the advantages of high flame retardant efficiency and good compatibility with materials. However, the hydrogen halide gas and residual dioxins released during their combustion process are harmful to the environment and human health, and are gradually subject to strict restrictions.

[0003] In contrast, halogen-free flame retardants have gradually become the focus of research, mainly including phosphorus, nitrogen, boron flame retardants and their composite systems. Phosphorus flame retardants achieve flame retardancy by forming a carbonized layer, but they are easy to absorb moisture and have poor compatibility with polymer materials; nitrogen flame retardants release inert gases to dilute the concentration of combustible gases to retard flames, but their efficiency is low when used alone, and they often need to be used in conjunction with phosphorus flame retardants; boron flame retardants isolate heat and oxygen by forming a glassy covering layer, and have the characteristics of smoke suppression and low toxicity, but their single flame retardancy is limited.

[0004] At present, multi-component synergistic flame retardant system has become an important trend in the development of flame retardant technology. By compounding components such as phosphorus, nitrogen, and boron and utilizing their respective synergistic effects, the flame retardant efficiency can be significantly improved and the shortcomings of a single flame retardant can be overcome. However, the production process of traditional compound flame retardants is complex and the cost is high, and there is still room for improvement in the flame retardant effect. Summary of the invention

[0005] The purpose of the present invention is to provide a N, P, B integrated flame retardant and a synthesis method and application thereof, which has excellent flame retardant effect.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a compound, the structure of which is shown in Formula 1: Formula 1.

[0007] The invention also provides the use of the compound as a flame retardant or in the preparation of a flame retardant.

[0008] The present invention also provides a method for synthesizing a flame retardant containing N, P and B, comprising the following steps: Piperazine diphosphate, melamine and boric acid are mixed and subjected to a three-stage heating reaction to obtain a flame retardant containing N, P and B: The three-stage heating reaction includes controlling the following temperatures: The temperature in the first stage is 190-220°C; The temperature of the second stage is 220-240°C; The temperature of the third stage is 240~260℃.

[0009] In the present invention, piperazine diphosphate provides phosphorus-based flame retardant function, melamine provides nitrogen-based flame retardant property, and boric acid is responsible for forming a glassy carbonized layer to enhance flame retardant performance and thermal stability.

[0010] Preferably, the molar ratio of the piperazine diphosphate, melamine and boric acid is 1:1.5~2.5:1.5~2.5.

[0011] Preferably, during the three-stage heating reaction, the oxygen content is less than 0.5%.

[0012] Preferably, the duration of the first stage is 0.8 to 1.2 hours.

[0013] Preferably, the duration of the second stage is 0.8 to 1.2 hours.

[0014] Preferably, the duration of the third stage is 2 to 4 hours.

[0015] The present invention also provides a flame retardant integrating N, P and B prepared by the above-mentioned synthesis method.

[0016] The present invention also provides a flame retardant material, comprising a plastic substrate and a flame retardant; The flame retardant contains the above compound or the above N, P, B integrated flame retardant.

[0017] Beneficial effects of the present invention: The flame retardant provided by the present invention integrates three flame retardant functions of nitrogen, phosphorus and boron into the same product. The components work synergistically during the combustion process to form a glassy carbonized layer and release inert gas, while suppressing smoke generation, thereby improving the flame retardant efficiency and thermal stability of the material.

[0018] The present invention completes all chemical reactions in a solid phase reactor through a one-pot reaction method, avoiding the complex operation of the traditional multi-step process, significantly simplifying the production process, and reducing equipment investment and operation difficulty. The reaction process adopts nitrogen protection to avoid the generation of oxidation by-products; the final product is a halogen-free flame retardant, which does not release toxic gases and meets environmental protection requirements. The present invention optimizes the raw material ratio and reaction conditions to complete the synthesis reaction at a lower temperature, with low energy consumption; at the same time, the product is a solid powder, which is easy to store and transport, further reducing the overall production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1This is the thermogravimetric analysis diagram of PMB; Figure 2 This is the infrared spectrum of PMB. DETAILED DESCRIPTION

[0020] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0021] Example 1

[0022] Select diphosphate piperazine, melamine and boric acid and weigh them accurately according to the molar ratio of 1:2:2. Mix the weighed raw materials evenly in a mixer for 30 minutes to ensure that the components are evenly distributed. Add the mixed raw materials to the solid phase kettle, turn on the stirring device, and stir at a speed of 30 revolutions per minute for 10 minutes to make the raw materials fully contact and disperse in the kettle. Turn off the stirring device, pass high-purity nitrogen into the solid phase kettle, replace the air in the kettle until the oxygen content is less than 0.5% to prevent the occurrence of oxidation reaction. First, heat to 200℃ and maintain this temperature for 1 hour to start the initial reaction; then heat to 235℃ and maintain for another 1 hour to promote the formation of chemical bonds of the elements in the flame retardant; finally heat to 250℃ and react for 2 hours to remove moisture. Stop heating and let the solid phase kettle cool naturally to room temperature. Open the lid of the kettle and take out the white powdery solid particles, which are the synthesized PMB flame retardant with a yield of 94.2%.

[0023] The chemical structure of PMB in the present invention is as follows:

[0024] Example 2 Select diphosphate piperazine, melamine and boric acid and weigh them accurately according to the molar ratio of 1.5:2.2:2.2. Mix the weighed raw materials evenly in a mixer for 30 minutes to ensure that the components are evenly distributed. Add the mixed raw materials to the solid phase kettle, turn on the stirring device, and stir at a speed of 30 revolutions per minute for 10 minutes to make the raw materials fully contact and disperse in the kettle. Turn off the stirring device, pass high-purity nitrogen into the solid phase kettle, replace the air in the kettle until the oxygen content is less than 0.5% to prevent the occurrence of oxidation reaction. First, heat to 195℃ and maintain this temperature for 1 hour to start the initial reaction; then heat to 230℃ and maintain for another hour to promote the formation of chemical bonds of the elements in the flame retardant; finally heat to 250℃ and react for 2 hours to remove moisture. Stop heating and let the solid phase kettle cool naturally to room temperature. Open the lid of the kettle and take out the white powdery solid particles, which are the synthesized PMB flame retardant with a yield of 95.1%.

[0025] Example 3 Select diphosphate piperazine, melamine and boric acid and weigh them accurately according to the molar ratio of 1:2:2.2. Mix the weighed raw materials evenly in a mixer for 30 minutes to ensure that the components are evenly distributed. Add the mixed raw materials to the solid phase kettle, turn on the stirring device, and stir at a speed of 30 revolutions per minute for 10 minutes to make the raw materials fully contact and disperse in the kettle. Turn off the stirring device, pass high-purity nitrogen into the solid phase kettle, replace the air in the kettle until the oxygen content is less than 0.5% to prevent the occurrence of oxidation reaction. First, heat to 200℃ and maintain this temperature for 1 hour to start the initial reaction; then heat to 240℃ and maintain for another hour to promote the formation of chemical bonds of the elements in the flame retardant; finally heat to 250℃ for reaction for 2.5 hours. Stop heating and let the solid phase kettle cool naturally to room temperature. Open the lid of the kettle and take out the white powdery solid particles, which are the synthesized PMB flame retardant with a yield of 94.5%.

[0026] Example 4

[0027] Select diphosphate piperazine, melamine and boric acid and weigh them accurately according to the molar ratio of 1:2:2. Mix the weighed raw materials evenly in a mixer for 30 minutes to ensure that the components are evenly distributed. Add the mixed raw materials to the solid phase kettle, turn on the stirring device, and stir at a speed of 30 revolutions per minute for 10 minutes to make the raw materials fully contact and disperse in the kettle. Turn off the stirring device, pass high-purity nitrogen into the solid phase kettle, replace the air in the kettle until the oxygen content is less than 0.5% to prevent the occurrence of oxidation reaction. First, heat to 200℃ and maintain this temperature for 1 hour to start the initial reaction; then heat to 240℃ and maintain for another hour to promote the formation of chemical bonds of the elements in the flame retardant; finally heat to 250℃ and react for 3 hours to remove moisture. Stop heating and let the solid phase kettle cool naturally to room temperature. Open the lid of the kettle and take out the white powdery solid particles, which are the synthesized PMB flame retardant with a yield of 94.7%.

[0028] Example 5

[0029] Select diphosphate piperazine, melamine and boric acid and weigh them accurately according to the molar ratio of 1:2:2. Mix the weighed raw materials evenly in a mixer for 30 minutes to ensure that the components are evenly distributed. Add the mixed raw materials to the solid phase kettle, turn on the stirring device, and stir at a speed of 30 revolutions per minute for 10 minutes to make the raw materials fully contact and disperse in the kettle. Turn off the stirring device, pass high-purity nitrogen into the solid phase kettle, replace the air in the kettle until the oxygen content is less than 0.5% to prevent the occurrence of oxidation reaction. First, heat to 195°C and maintain this temperature for 1 hour to start the initial reaction; then heat to 240°C and maintain for another hour to promote the formation of chemical bonds of the elements in the flame retardant; finally heat to 250°C and react for 2 hours to remove moisture. Stop heating and let the solid phase kettle cool naturally to room temperature. Open the lid of the kettle and take out the white powdery solid particles, which are the synthesized PMB flame retardant with a yield of 94.2%.

[0030] Experimental example

[0031] Thermogravimetric (TG) analysis of PMB flame retardant is performed. The thermogravimetric analysis of PMB is shown in the figure below: Figure 1 shown.

[0032] Thermogravimetric analysis (TGA) results clearly show the excellent thermal stability of PMB compounds. Specifically, the temperature of PMB at 1% weight loss is 247.5°C, while the temperature at 5% weight loss is 276.6°C. These data show that PMB can maintain stable physical and chemical properties without decomposition in high temperature environments.

[0033] This good thermal stability makes PMB an ideal choice for polypropylene (PP) applications, especially during plastic processing. The injection molding processing temperature of PP is usually between 160°C and 220°C, which is much lower than the weight loss temperature of PMB. Therefore, during the injection molding process, PMB can effectively maintain its flame retardant properties and avoid decomposition or performance degradation caused by high temperature, thereby ensuring the safety and effectiveness of the final product during use.

[0034] The infrared spectrum (FT-IR) of PMB flame retardant is analyzed. Figure 2 shown.

[0035] In this infrared spectrum analysis, multiple characteristic absorption peaks were detected, which further verified the molecular structure and functional group existence of the product PMB. - ¹ and 3331 cm - The absorption peak of ¹ corresponds to the stretching vibration of NH on the piperazine ring, indicating the presence of an amino structure in the compound; 1653 cm -The absorption peak of ¹ is the bending vibration peak of NH on the piperazine ring, which further confirms the structure of the piperazine ring.

[0036] In addition, 1465 cm - The absorption peak of ¹ can be attributed to the bending vibration of -CH2 in the piperazine ring, which also supports the existence of piperazine. 1087 cm - The absorption peak at ¹ corresponds to the characteristic absorption of CC on the piperazine ring, while the absorption peak at 1026 cm - The absorption peak of ¹ represents the stretching vibration of CN, which indicates the connection between the nitrogen atom and the carbon atom in the piperazine ring.

[0037] In terms of phosphorus functional groups, the stretching vibration peak of P=O appears at 1143 cm - ¹, the characteristic absorption peak of PO is at 972 cm - ¹, the stretching vibration absorption peak of P-OH is at 983cm - ¹, the presence of these peaks confirms the presence of phosphorus and indicates a possible phosphate structure.

[0038] About - NH3 + The stretching vibration peak and bending vibration peak appear at 3129 cm - ¹ and 1549 cm - ¹, further indicating the presence of amino groups.

[0039] The characteristic peaks of triazine ring include 1651 cm - ¹C=N stretching vibration peak, 1436 cm - ¹CN stretching vibration peak, and 777 cm - The appearance of these peaks means that PMB also contains triazine structure, which enhances its flame retardant properties and thermal stability.

[0040] Finally, the bending vibration of BO at 915 cm - ¹ and 813 cm - The absorption peak at ¹ confirms the presence of boron, indicating that the compound contains boron element, which may be closely related to its flame retardant properties.

[0041] The above infrared spectrum analysis results clearly show that the synthesis of PMB of the present invention is successful, verify the structure and functional group characteristics of the target compound, and lay a foundation for subsequent performance tests.

[0042] Preparation of PBM / polypropylene (PP) After extrusion by a twin-screw extruder, cutting and granulation by a pelletizer, and finally injection molding by an injection molding machine, standard specimens for mechanical and combustion performance tests are obtained. The tensile strength and flexural strength of PP composite materials are tested according to GB / T 1040-2018 standard, with a tensile speed of 10 mm / min and a specimen size of 160×10×4 mm 3 , bending speed 10mm / min, spline size 80×10×4mm 3 The impact test is in accordance with GB / T 1843-1996, and the sample size is 80×10×4mm 3 (V-notch). Limiting oxygen index test is based on GB / T 2406. 2-2009 standard, sample size is 10×10×4mm 3 ; Vertical burning test: According to UL94 standard, the sample size is 125×13×5 mm 3 .

[0043] Table 1 Flame retardant test data of PP and its composites Performance test samples UL-94 LOI / % PP combustion 17.50 PP / 10%PMB combustion 18.44 PP / 15%PMB V-1 20.65 PP / 20%PMB V-0 25.08 PP / 25%PMB V-0 28.15 As shown in Table 1, different addition amounts of PMB flame retardant have a significant effect on the flame retardant properties of polypropylene (PP) materials. As the addition amount of PMB flame retardant increases, the oxygen index (LOI) value of the material gradually increases. This phenomenon shows that the introduction of PMB effectively improves the flame retardant properties of polypropylene.

[0044] Specifically, when the addition amount is 10%, the LOI of the PP sample is 18.44, which has not yet reached the flame retardant standard. This shows that at this addition amount, the flame retardant performance of PMB is not obvious. When the addition amount is increased to 15%, the UL-94 grade of the PP sample is improved to V-1, and the LOI value increases to 20.65, indicating that the flame retardant performance of the material is further enhanced and can effectively delay the combustion process.

[0045] More significantly, when the addition of PMB flame retardant reaches 20%, the UL-94 grade of the PP sample reaches V-0, and the LOI value rises to 25.08. This result shows that the synergistic effect of PMB is fully exerted at this concentration, significantly improving the flame retardancy of polypropylene. The V-0 grade means that the material can self-extinguish in the combustion test, and the burning time and dripping melt have little effect on the test results, showing excellent safety.

[0046] When the amount of PMB added continued to increase to 25%, the sample still maintained the V-0 level, and the LOI value further increased to 28.15, indicating that high concentrations of PMB can continuously enhance the flame retardant properties of polypropylene. This performance improvement can be attributed to the synergistic effect of nitrogen, phosphorus, boron and other elements in PMB, which greatly inhibit the possibility of flame propagation by promoting the formation of a carbonized layer and improving the thermal stability of the material.

[0047] In summary, the application of PMB as a flame retardant in polypropylene not only improves the flame retardant level of the material, but also significantly improves its thermal stability, providing a good foundation for the development of high-performance flame retardant materials.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A compound, characterized in that The structure of the compound is shown in Formula 1: Formula 1.

2. Use of the compound according to claim 1 as a flame retardant or in the preparation of a flame retardant.

3. A method for synthesizing a flame retardant containing N, P and B, characterized in that: The following steps are involved: Piperazine diphosphate, melamine and boric acid are mixed and subjected to a three-stage heating reaction to obtain a flame retardant containing N, P and B: The three-stage heating reaction includes controlling the following temperatures: The temperature in the first stage is 190-220°C; The temperature of the second stage is 220-240°C; The temperature of the third stage is 240~260℃.

4. The synthesis method according to claim 3, characterized in that The molar ratio of the piperazine diphosphate, melamine and boric acid is 1:1.5-2.5:1.5-2.

5.

5. The synthesis method according to claim 3, characterized in that During the three-stage heating reaction, the oxygen content is lower than 0.5%.

6. The synthesis method according to claim 3, characterized in that The duration of the first stage is 0.8~1.2h.

7. The synthesis method according to claim 3, characterized in that The duration of the second stage is 0.8~1.2h.

8. The synthesis method according to claim 3, characterized in that The duration of the third stage is 2 to 4 hours.

9. A flame retardant containing N, P and B prepared by the synthesis method according to any one of claims 3 to 8.

10. A flame retardant material, characterized in that: Includes plastic substrates and flame retardants; The flame retardant contains the compound according to claim 1 or the N, P, and B integrated flame retardant according to claim 9.

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