Phosphazene charring agent, preparation thereof and application of phosphazene charring agent in flame-retardant material
By preparing phosphazene charring agents, a polyphosphoric acid coating layer is formed in LLDPE using phosphorus and nitrogen groups, solving the flammability problem of LLDPE and achieving an environmentally friendly and efficient flame retardant effect.
Patent Information
- Application Number
- CN202511836047.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-02-27
AI Technical Summary
Linear low-density polyethylene (LLDPE) is flammable, burns rapidly, produces large droplets and a lot of smoke, and contains halogenated flame retardants which are harmful to the environment. Therefore, there is a need to develop environmentally friendly and efficient flame retardants.
The charring agent is a phosphazene-based agent prepared by reacting hexachlorocyclotriphosphazene with N-aminoethylpiperazine. It contains phosphorus and nitrogen groups, which form polyphosphoric acid during pyrolysis, thus isolating oxygen, promoting dehydration and charring, and providing flame retardant effect.
This improves the flame retardant properties of LLDPE by lowering the material surface temperature, releasing non-flammable gases, and generating a coating layer to isolate oxygen, thus achieving excellent flame retardant effects.
Smart Images
Figure CN121574158A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of flame-retardant materials, and particularly relates to a phosphazene charring agent, preparation thereof and application thereof in flame-retardant materials. BACKGROUND
[0002] Polyethylene (PE) is one of the most commonly used plastics with excellent electrical insulation and chemical stability, and is classified into high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) and ultra-high molecular weight polyethylene (UHMWPE) according to the distribution of molecular weight and the chain structure. LLDPE is often made into films, pipes, wires and cables due to its good flexibility, ductility, cold resistance and environmental stress cracking resistance, and is widely used in daily life, agriculture, national defense, chemical industry and other fields. However, the oxygen index of LLDPE is only 17.4%, which belongs to flammable material, and has the disadvantages of fast burning speed, easy to produce melt drops and large smoke, which greatly reduces the application range of PE.
[0003] The halogen-containing flame retardant produces a large amount of harmful gas during combustion, which seriously endangers human health and the ecological environment, so the halogen-free, environmentally friendly, smoke-suppressing and anti-dripping flame retardant has become a new research hotspot. SUMMARY
[0004] The application aims to overcome the shortcomings of the prior art, and provides a phosphazene charring agent, preparation thereof and application thereof in flame-retardant materials.
[0005] The phosphazene charring agent of the application has the following structure: .
[0006] The phosphazene charring agent contains amino groups and phosphorus-nitrogen groups, and the phosphorus and nitrogen elements are alternately connected by single and double bonds, which has excellent dehydration and carbonization effect. After thermal decomposition, polyphosphoric acid is formed on the surface of the polymer matrix to isolate oxygen and promote the dehydration and carbonization of the polymer matrix, and can provide good flame-retardant effect in the polyethylene flame-retardant composite material.
[0007] The phosphazene charring agent of the application is obtained by the reaction of hexachlorocyclotriphosphazene and N-aminoethylpiperazine;
[0008] The structure of hexachlorocyclotriphosphazene is as follows: .
[0009] The preparation method of the phosphazene charring agent comprises the following specific contents: hexachlorocyclotriphosphazene is dissolved in an organic solvent, N-aminoethylpiperazine and an acid binding agent are added, and the mixture is heated and stirred to react, so that the phosphazene charring agent is obtained;
[0010] The molar ratio of hexachlorocyclotriphosphazene to N-aminoethylpiperazine is 1:1-7, and preferably 1:6;
[0011] The N-aminoethylpiperazine is added at 20-35 DEG C, the reaction temperature is 40-80 DEG C, and the reaction time is 4-6 hours;
[0012] The reaction is carried out in an inert atmosphere, the organic solvent is acetonitrile, the acid binding agent is triethylamine, the tail gas generated in the reaction is absorbed by sodium hydroxide solution, and after the reaction is completed, the product is purified (suction filtration, repeated washing), dried, and the phosphazene charring agent is obtained.
[0013] The phosphazene charring agent of the application can be applied to a flame-retardant polyethylene composite material, comprising the following specific contents:
[0014] The flame-retardant polyethylene composite material comprises the following components and mass fractions:
[0015] Linear low density polyethylene 150 parts, 2-carboxyethyl phenyl phosphinic acid 0-25 parts, ammonium polyphosphate 15-35 parts, melamine 3-8 parts, dipentaerythritol 10-20 parts and phosphazene flame retardant 1-15 parts are placed in a high-speed mixer, and pre-mixed at room temperature to ensure uniform dispersion of each component.
[0016] Conventional linear low density polyethylene in the art can be used in the application. Each component is melt-mixed and injection molded into a flame-retardant polyethylene composite material; preferably, the temperature of melt-mixing is 140-180 DEG C, and the time of melt-mixing is 8-12 minutes. Preferably, the temperature of injection molding is 150-190 DEG C.
[0017] Compared with the prior art, the application has the following beneficial effects:
[0018] The application uses hexachlorocyclotriphosphazene with a cyclic phosphazene structure as a raw material, and phosphorus and nitrogen elements are connected by single and double bonds alternately. Due to the activity of phosphorus and chlorine, chlorine is easily replaced to synthesize the phosphazene charring agent. The phosphazene charring agent contains phosphorus and nitrogen groups and a large amount of phosphorus and nitrogen elements, has good thermal stability and excellent dehydration and carbonization effect, absorbs a large amount of heat when the phosphazene bond decomposes, reduces the surface temperature of the material, releases a large amount of non-combustible gas and decomposes to form a large amount of phosphoric acid during the combustion process. The phosphoric acid exposed to high temperature generates polyphosphoric acid covering the surface of the material, which plays a role in isolating oxygen, and the polyphosphoric acid can further promote the dehydration and carbonization of the polymer in the composite material at high temperature. Through the combined action of gas phase and condensed phase, excellent flame-retardant effect is achieved. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 The Fourier transform infrared spectrum is shown for the phosphazene char-forming agent prepared in Example 1 of this invention.
[0020] Figure 2 The image shows the 1H NMR spectrum of the phosphazene char-forming agent prepared in Example 1 of this invention.
[0021] Figure 3 This is a high-resolution mass spectrum of the phosphazene char-forming agent prepared in Example 1 of the present invention.
[0022] Figure 4 This is a mass spectrometry diagram of the phosphazene char-forming agent prepared in Example 1 of the present invention; wherein a, b, c, d, e, f, and g are all ion structures formed by ionization.
[0023] Figure 5 Thermogravimetric curve of the phosphazene char-forming agent prepared in Example 1 of the present invention. Detailed Implementation
[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. It should be noted that the embodiments described in this invention are only for further explanation and illustration, and not for limiting their application scope. Based on this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention.
[0025] Examples 1-4 describe the preparation of phosphazene charring agents.
[0026] Example 1
[0027] 0.1 mol of hexachlorocyclotriphosphazene was placed in a 500 mL three-necked flask equipped with a thermometer and a spherical condenser. 0.615 mol of N-aminoethylpiperazine (AEP) was slowly added dropwise through a polytetrafluoroethylene constant-pressure dropping funnel at room temperature. Under reaction conditions of acetonitrile as the solvent and triethylamine as the acid-binding agent, the reaction apparatus was placed in an oil bath at 80 °C for 6 h. The product was filtered and then washed several times with anhydrous ethanol and acetonitrile, finally dried under vacuum at 80 °C to constant weight. A milky white solid powder, HAEP, was obtained, which is a phosphazene charring agent.
[0028] The structure of the milky white solid powder HAEP obtained in this embodiment was characterized by Fourier transform infrared spectroscopy: A small amount of milky white solid powder HAEP was placed in a mortar, a certain amount of KBr was added, and the mixture was thoroughly ground and mixed. The mixed sample powder was then pressed into a pellet and subjected to Fourier transform infrared spectroscopy, with a test range of 4000 cm⁻¹. -1 -400cm -1 ,like Figure 1 As shown, Figure 1In this context, a represents N-aminoethylpiperazine, b represents hexachlorocyclotriphosphazene, and c represents a phosphazene charring agent. Figure 1 It can be known that 1462cm -1 It is the absorption peak of the bending vibration of CH in CH2, at 1243 cm⁻¹. -1 The peak at 945 cm⁻¹ represents the characteristic absorption peak of the stretching vibrations of PN and P=N bonds. -1 The characteristic absorption peak of PNC is generated at 579 cm⁻¹ in curve b. -1 The characteristic absorption peak of P-Cl disappears in curve c. Based on relevant literature and infrared spectroscopy analysis results, it has been preliminarily confirmed that HAEP has been synthesized.
[0029] The 1H NMR spectrum of the milky white solid powder HAEP obtained in this embodiment was analyzed. 1 1H NMR characterization: A small amount of milky white solid powder HAEP was dissolved in dimethyl sulfoxide (DMSO) and measured using a nuclear magnetic resonance spectrometer at a frequency of 400 MHz. The resulting 1H NMR spectrum is shown below. Figure 2 As shown. By Figure 2 It can be seen that δ=2.5ppm is the solvent peak of DMSO, and the peaks at δ=8.01ppm and δ=9.27ppm are the chemical shifts of hydrogen atoms at the ortho and meta positions of -CH2- on the carbon-nitrogen six-membered ring. Due to the symmetrical structure, the other two hydrogen atoms of the carbon-nitrogen six-membered ring have the same chemical environment. The singlet at δ=3.28ppm is the chemical shift of hydrogen atom on -NH2-, the peak at δ=2.88ppm is the chemical shift of hydrogen atom on -CH2- connected to the carbon-nitrogen six-membered ring, and the peak at δ=1.94ppm is the chemical shift of hydrogen atom on -CH2- connected to -NH2. The analysis of the peak positions and peak areas in the NMR spectrum is consistent with the designed structure of HAEP, further indicating that HAEP has been successfully synthesized.
[0030] High-resolution mass spectrometry (HMS) analysis was performed on the milky white solid powder HAEP obtained in this embodiment: 20 mg of milky white solid powder HAEP was taken and measured using a high-resolution mass spectrometer, with a test range of 0–2000. Mass spectrometry is a method that ionizes a sample to generate ions with different mass-to-charge ratios (the ratio of mass m to charge z) to determine the molecular mass and molecular structure of the sample. The mass spectrum of HAEP is shown below. Figure 3 As shown, by Figure 3 We know that m / Z = 302, 314, 326, 342, 356, 579, and 624 correspond to respectively Figure 4 The values of a, b, c, d, e, f, and g obtained by mass spectrometry testing are consistent with the theoretical values of HAEP.
[0031] In summary, the characterization results of mass spectrometry, infrared, and nuclear magnetic prove that the phosphazene charring agent has been successfully synthesized. The white solid powder HAEP prepared in the embodiment is a phosphazene charring agent, and its structural formula is as shown below: ;
[0032] The specific synthesis route of the embodiment is as follows: .
[0033] The prepared phosphazene charring agent is subjected to thermogravimetric analysis, and the thermogravimetric curve is as shown in Figure 5 . A small amount of water is volatilized at 95℃-200℃, and there is slight weight loss; the main thermal decomposition interval is 300℃-390℃, and the maximum thermal weight loss rate temperature is about 347℃, and the thermal degradation process in this interval helps to form an expanded carbon layer. It can be seen that the phosphazene charring agent prepared in the embodiment has good thermal stability, and can meet the requirements of linear low-density polyethylene flame retardation.
[0034] Example 2
[0035] 1 mol of hexachlorocyclotriphosphazene is placed in a 500 ml three-necked flask with a thermometer and a spherical condenser, 4 mol of N-aminoethylpiperazine (AEP) is placed in a polytetrafluoroethylene constant pressure dropping funnel, and is slowly added at room temperature, acetonitrile is used as the reaction solvent, triethylamine is used as the acid binding agent, the reaction device is placed in an oil bath at 50℃ for 6 h. The product is filtered, then washed with anhydrous ethanol and acetonitrile several times, and finally dried under vacuum at 80℃ until the weight is constant. A white solid powder, i.e. a phosphazene charring agent, is obtained.
[0036] Example 3
[0037] 1 mol of hexachlorocyclotriphosphazene is placed in a 500 ml three-necked flask with a thermometer and a spherical condenser, 5 mol of N-aminoethylpiperazine (AEP) is placed in a polytetrafluoroethylene constant pressure dropping funnel, and is slowly added at room temperature, acetonitrile is used as the reaction solvent, triethylamine is used as the acid binding agent, the reaction device is placed in an oil bath at 60℃ for 6 h. The product is filtered, then washed with anhydrous ethanol and acetonitrile several times, and finally dried under vacuum at 80℃ until the weight is constant. A white solid powder, i.e. a phosphazene charring agent, is obtained.
[0038] Example 4
[0039] Put 1 mol of hexachlorocyclotriphosphazene into a 500 ml three-necked flask with a thermometer and a spherical condenser. Put 7 mol of N-aminoethylpiperazine (AEP) into a polytetrafluoroethylene constant pressure dropping funnel and slowly drop at room temperature. In acetonitrile as the reaction solvent, triethylamine as the acid binding agent, the reaction device is placed in an oil bath at 80°C for 6 hours. After the product is filtered, it is washed repeatedly with anhydrous ethanol and acetonitrile several times, and finally dried under vacuum at 80°C to constant weight. A milky white solid powder, i.e. phosphazene charring agent, is obtained.
[0040] Example 5
[0041] Preparation of flame-retardant polyethylene composite material with phosphazene charring agent.
[0042] Table 1 Formulation, linear low density polyethylene, 2-carboxyethyl phenyl phosphinic acid, ammonium polyphosphate (polymerization degree above 50), melamine, dipentaerythritol powder and phosphazene charring agent prepared in Example 1 are mixed by torque rheometer at 160°C for 10 min, extruded by extruder, and then made into flame-retardant polyethylene resin composite material by screw injection molding machine at 170°C.
[0043] Table 1 Formulation of flame-retardant polyethylene composite material (g):
[0044] The mechanical properties and flame-retardant properties of the prepared flame-retardant polyethylene resin composite material are tested, and 5 samples are taken for each test, and the test results are averaged. The tensile property test refers to GB / T 1040.1-2025, the tensile speed is 50 mm / min, and the sample size is 100 mm x 10 mm x 4 mm; the bending property test refers to GB / T9341-2008, the bending speed is 2 mm / min, and the sample size is 80 mm x 10 mm x 4 mm; the impact property test refers to GB / T1843-2008, the sample size is 50 mm x 6 mm x 4 mm; the vertical burning test (UL-94) refers to GB / T2408-2021, using CZF-3 type vertical burning tester of Nanjing Jiangning Analysis Instrument Factory; the limiting oxygen index test (LOI) refers to GB / T2406.2-2009, using JF-3 type oxygen index analyzer of Nanjing Jiangning Analysis Instrument Factory. The test results are shown in Table 2.
[0045] Table 2 Performance test results of flame-retardant polyethylene resin composite material:
[0046] From the data in Table 2, it can be seen that with the increase of phosphazene charring agent HAEP, the tensile strength and flexural modulus show an upward trend, the impact strength remains basically unchanged, the vertical burning grade of the system increases from V-1 to V-0 grade, and the oxygen index of the composite system also continuously increases, indicating that the phosphazene charring agent HAEP plays a good flame-retardant effect in the material.
Claims
1. A phosphazene-based charring agent, characterized in that, The structural formula of the phosphazene-based charring agent is as follows: 。 2. The phosphazene charring agent according to claim 1, characterized in that, The phosphazene charring agent contains amino groups and phosphorus-nitrogen groups. Phosphorus and nitrogen elements are linked alternately by single and double bonds. After being heated and decomposed, they form polyphosphoric acid, which covers the surface of the polymer matrix. This isolates oxygen and promotes the dehydration and charring of the polymer matrix, thus achieving a flame retardant effect.
3. The method for preparing a phosphazene charring agent according to claim 1, characterized in that, The phosphazene charring agent is obtained by reacting hexachlorocyclotriphosphazene and N-aminoethylpiperazine.
4. The method for preparing a phosphazene charring agent according to claim 3, characterized in that, The molar ratio of the hexachlorocyclotriphosphazene to the N-aminoethylpiperazine is 1:1~7; the reaction temperature is 40℃~80℃, and the reaction time is 4h~6h.
5. The method for preparing a phosphazene charring agent according to claim 4, characterized in that, The molar ratio of the hexachlorocyclotriphosphazene to the N-aminoethylpiperazine is 1:
6.
6. The method for preparing a phosphazene charring agent according to claim 3, characterized in that, The process includes the following: dissolving the hexachlorocyclotriphosphazene in an organic solvent, adding the N-aminoethylpiperazine and an acid-binding agent to react and obtain the phosphazene-based charring agent.
7. The method for preparing a phosphazene charring agent according to claim 6, characterized in that, The N-aminoethylpiperazine is added at 20°C to 35°C, the reaction is carried out under an inert atmosphere, the organic solvent is acetonitrile, and the acid-binding agent is triethylamine; the tail gas generated by the reaction is absorbed by an aqueous sodium hydroxide solution; after the reaction is completed, the product is purified and dried to obtain the phosphazene charring agent.
8. The application of a phosphazene charring agent according to claim 1 in flame-retardant materials, characterized in that, The phosphazene-based charring agent is applied to flame-retardant polyethylene composite materials.
9. The application of a phosphazene charring agent according to claim 8 in flame-retardant materials, characterized in that, The flame-retardant polyethylene composite material comprises the following components and parts by weight: 150 parts of linear low-density polyethylene, 0-25 parts of 2-carboxyethylphenyl hypophosphite, 15-35 parts of ammonium polyphosphate, 3-8 parts of melamine, 10-20 parts of dipentaerythritol, and 1-15 parts of the phosphazene flame retardant.
10. The application of a phosphazene charring agent according to claim 9 in flame-retardant materials, characterized in that, The flame-retardant polyethylene composite material is prepared by melting and mixing the components at 140℃~180℃ for 8min~12min and then injection molding at 150℃~190℃.