High-molecular-weight phosphamide aggregate flame retardant and preparation method thereof

Abstract

The invention discloses a high-molecular-weight phosphamide aggregate flame retardant and a preparation method thereof.The method comprises the steps that phosphoryl dichloride compounds and piperazine anhydrous serve as raw materials, an amino-terminated phosphamide polymer is synthesized through a condensation reaction, and the phosphamide polymer flame retardant is obtained. The high-molecular-weight phosphamide aggregate flame retardant is obtained through a ring-opening reaction of amino-terminated groups and epoxy groups between the high-molecular-weight phosphamide aggregate flame retardant and triglycidyl isocyanurate. Compared with an existing small-molecule flame retardant, the flame retardant is higher in thermal stability, better in compatibility with a high polymer material matrix, not prone to migration and capable of achieving synergistic flame retardance due to the fact that the flame retardant contains phosphorus and nitrogen structural units at the same time, and when the prepared flame retardant is added into TPU, PC, EP, PET and other transparent matrixes, the flame retardance is improved. The flame retardant property of the transparent base material can be improved, and meanwhile, good mechanical property and high light transmittance can be kept. In addition, the preparation method disclosed by the invention is simple and easy to control, high in yield, wide in source of required raw materials, easy for industrial production and wide in industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of halogen-free flame-retardant polymers, and particularly relates to a high-molecular-weight phosphamide aggregate flame retardant and a preparation method thereof. Background Art

[0002] Due to their excellent mechanical properties and processing performance, high-molecular materials have attracted wide attention. However, since high-moleculars contain a large amount of flammable C-H structures, they are extremely prone to combustion when encountering an open flame, resulting in fire accidents during their use, which limits the application of high-molecular materials in fields such as electronic appliances, automotive parts, and aerospace. Therefore, it is necessary to carry out flame-retardant modification on high-molecular materials.

[0003] Halogen-containing flame retardants release more flue gas and hydrogen halide gas during combustion, which limits their application to a certain extent. Inorganic flame retardants are inexpensive, low-smoke, and low-toxic, but often require a large addition amount, seriously affecting the mechanical properties of high-molecular materials. In recent years, phosphorus-nitrogen flame retardants have been widely used in the flame-retardant modification of polymers due to their advantages such as low smoke and non-toxicity. For example, some phosphorus-nitrogen flame retardants reported in Chinese Patent Publication Nos. CN115651025, CN113402715, and CN115521466 do not contain halogens and have good effects, and can replace some halogen-containing flame retardants. In phosphamide flame retardants, phosphorus elements can promote the carbonization of polymers during combustion, while the inert gas generated by nitrogen elements can dilute the concentration of combustible gases, enabling phosphamide flame retardants to play both a condensed-phase flame-retardant role and a gas-phase flame-retardant role, and forming a better expanded carbon layer. However, most intumescent flame retardants have problems such as low decomposition temperature, easy precipitation during long-term use, great influence on the mechanical properties of materials, and damage to the transparency of the material itself, affecting the performance and application range of high-molecular materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-molecular-weight phosphamide aggregate flame retardant and a preparation method thereof to overcome the problems of low flame-retardant efficiency, low thermal stability, easy precipitation during long-term use, and great influence on material properties existing in existing phosphorus-containing flame retardants, and it can be particularly used to improve the flame-retardant performance of transparent substrates while maintaining excellent mechanical properties and high light transmittance.

[0005] The present invention adopts the following technical scheme:

[0006] A preparation method of a high-molecular-weight phosphamide aggregate flame retardant includes the following steps: First, using phosphoryl dichloride compounds and anhydrous piperazine as raw materials, a terminal amino phosphamide polymer is synthesized through a condensation reaction to obtain a phosphamide polymer flame retardant, and then this compound and triglycidyl isocyanurate are subjected to a ring-opening reaction between the terminal amino group and the epoxy group to obtain a high-molecular-weight phosphamide aggregate flame retardant.

[0007] The preparation method of the phosphoramide polymer flame retardant (Compound C) is to form it by removing hydrochloric acid through solution polycondensation reaction of phosphoryl dichloride compounds (Compound A) and anhydrous piperazine (Compound B); the reaction process can be expressed as:

[0008]

[0009] In the formula, n is an integer from 15 to 100; in the bifunctional compound A, R is an aryloxy group or an aromatic ring. Specifically, its preparation method may include the following steps:

[0010] Add Compound B and a solvent into an anhydrous and anaerobic reactor, stir at a temperature of -5°C to 10°C until piperazine is completely dissolved in the solvent, then add triethylamine into the reactor and stir well; dissolve the bifunctional compound A in the solvent, stir well and place it in a dropping funnel, and slowly add it dropwise into the above reactor within 6 h. During the dropping process, keep the temperature of the solution in the reactor at -5°C to 10°C. After the dropping is completed, raise the reaction temperature to 30 - 50°C and continue the reaction for 5 - 10 h, then continue to raise the temperature to 55°C - 65°C and continue the reaction for 6 - 12 h. After the reaction is completed, wash the reactant with water to obtain a crude product, and dry the crude product to obtain a pale yellow solid, which is the phosphoramide polymer flame retardant.

[0011] Further, the phosphoryl dichloride compound is selected from any one of phenylphosphoryl dichloride and phenyl dichlorophosphate.

[0012] Further, the solvent is selected from any one of dichloromethane, dichloroethane, chloroform, acetonitrile, tetrahydrofuran or N, N - dimethylformamide.

[0013] Further, the molar ratio of the bifunctional compound A to Compound B is 1:(1 - 1.5), and the molar ratio of Compound B to triethylamine is 1:2.

[0014] After obtaining the phosphoramide polymer flame retardant, crush and mix the phosphoramide polymer flame retardant and triglycidyl isocyanurate evenly, keep at 120°C - 130°C, and knead for 3 h - 5 h, then raise the temperature to 140°C - 160°C and continue kneading for 3 h - 5 h. It is represented by the reaction formula:

[0015]

[0016] In the formula,

[0017] Further, the molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:(1 - 1.2).

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] 1. Compared with the existing small - molecule flame retardants, the high - molecular - weight phosphoramide aggregate flame retardant proposed by the present invention has higher thermal stability, better compatibility with the polymer material matrix, is not easy to migrate, has excellent durability, and also reduces the influence of the flame retardant on the mechanical properties of the matrix material.

[0020] 2. The phosphoramide aggregate flame retardant prepared by the present invention contains both phosphorus and nitrogen structural units at the same time. Utilizing the synergistic flame - retardant principle of phosphorus and nitrogen elements in the molecule, it can form a better expanded carbon layer and has a better flame - retardant effect on the base material.

[0021] 3. The molecular weight of the phosphoramide aggregate flame retardant prepared by the present invention can reach more than 10,000, and there is a melting temperature. Therefore, when the flame retardant provided by the present invention is added to transparent materials such as TPU, PC, EP, and PET, the flame retardant can be dispersed in the material at the molecular level, while improving the flame - retardant performance and mechanical properties of the material, maintaining a high light transmittance.

[0022] 4. The solution polycondensation method adopted by the present invention is simple, easy to control, has a high yield, and the required raw materials are widely sourced, easy to industrialize, and has broad industrial application prospects. Brief Description of the Drawings

[0023] Figure 1 For the comparison of the light - transmission effects of different samples on the flower pictures below, the samples are TPU composites under ambient light, a: TPU, b: 2 - TPU, c: 3 - TPU, d: 4 - TPU, e: 5 - TPU. Detailed Embodiments

[0024] The following further illustrates the present invention with specific examples, but the implementation manners of the present invention are not limited thereto.

[0025] For those not specified in the embodiments of the present invention, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. The raw materials, reagents, etc. without indicating the manufacturer can be obtained as conventional products through commercial purchase.

[0026] Example 1

[0027] The molar ratio of phenylphosphonic dichloride to anhydrous piperazine is 1:1.2. At 5 °C, 0.24 mol of anhydrous piperazine is dissolved in 400 ml of acetonitrile, and then added to a four-necked flask. Then, 0.2 mol of phenylphosphonic dichloride is weighed and dissolved in 100 ml of acetonitrile, added to a constant-pressure dropping funnel. 0.48 mol of triethylamine is added to the flask, and stirred under the atmosphere of nitrogen as a protective gas; under the condition of an ice-water bath, the flask is at 5 °C; the solution in the dropping funnel is slowly added dropwise into the flask over 6 h; the resulting mixture is stirred at 30 °C for 10 h, and then stirred at 65 °C for 6 h. After the reaction is completed, the solid product is obtained by washing with water, removing impurities and drying. Finally, the obtained solid product is dried in a vacuum oven at 80 °C to obtain a phosphoramide polymer flame retardant.

[0028] The molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:1. First, the phosphoramide polymer flame retardant and triglycidyl isocyanurate are put into a pulverizer and mixed evenly. Then, the mixed powder is put into an oven at 120 °C and reacted for 3 h, and then put into an oven at 150 °C and reacted for 5 h to obtain a brown solid, which is a high-molecular-weight phosphoramide aggregate flame retardant.

[0029] Example 2

[0030] The molar ratio of phenylphosphonic dichloride to anhydrous piperazine is 1:1.5. At -5 °C, 0.3 mol of anhydrous piperazine is dissolved in 400 ml of chloroform, and then added to a four-necked flask. Then, 0.2 mol of phenylphosphonic dichloride is weighed and dissolved in 100 ml of chloroform, added to a constant-pressure dropping funnel. 0.6 mol of triethylamine is added to the flask, and stirred under the atmosphere of nitrogen as a protective gas; under the condition of a cold well, the flask is at -5 °C; the solution in the dropping funnel is slowly added dropwise into the flask over 6 h; the resulting mixture is stirred at 50 °C for 10 h, and then stirred at 55 °C for 6 h. After the reaction is completed, the solid product is obtained by washing with water, removing impurities and drying. Finally, the obtained solid product is dried in a vacuum oven at 80 °C to obtain a phosphoramide polymer flame retardant.

[0031] The molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:1.2. First, the phosphoramide polymer flame retardant and triglycidyl isocyanurate are put into a pulverizer and mixed evenly. Then, the mixed powder is put into an oven at 130 °C and reacted for 5 h, and then put into an oven at 160 °C and reacted for 5 h to obtain a brown solid, which is a high-molecular-weight phosphoramide aggregate flame retardant.

[0032] Example 3

[0033] The molar ratio of phenyl dichlorophosphate to anhydrous piperazine is 1:1. At 10 °C, 0.2 mol of anhydrous piperazine is dissolved in 400 ml of chloroform, and then added to a four-necked flask. Then, 0.2 mol of phenyl dichlorophosphate is weighed and dissolved in 100 ml of chloroform, added to a constant pressure dropping funnel. 0.4 mol of triethylamine is added to the flask, and stirred under the atmosphere of nitrogen as a protective gas; the flask is kept at 10 °C; the solution in the dropping funnel is slowly added dropwise to the flask within 6 h; the resulting mixture is stirred at 35 °C for 10 h, and then stirred at 55 °C for 6 h. After the reaction is completed, the solid product is obtained by washing with water, removing impurities and drying. Finally, the obtained solid product is dried in a vacuum oven at 80 °C to obtain the phosphoramide polymer flame retardant.

[0034] The molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:1. First, the phosphoramide polymer flame retardant and triglycidyl isocyanurate are put into a pulverizer and mixed evenly. Then, the mixed powder is put into an oven at 125 °C and reacted for 4.5 h, and then put into an oven at 155 °C and reacted for 4.5 h to obtain a brown solid, which is the high molecular weight phosphoramide aggregate flame retardant.

[0035] Example 4

[0036] The molar ratio of phenyl dichlorophosphate to anhydrous piperazine is 1:1. At 0 °C, 0.3 mol of anhydrous piperazine is dissolved in 400 ml of chloroform, and then added to a four-necked flask. Then, 0.2 mol of phenyl dichlorophosphate is weighed and dissolved in 100 ml of chloroform, added to a constant pressure dropping funnel. 0.6 mol of triethylamine is added to the flask, and stirred under the atmosphere of nitrogen as a protective gas; under the condition of an ice-water bath, the flask is kept at 0 °C; the solution in the dropping funnel is slowly added dropwise to the flask within 6 h; the resulting mixture is stirred at 30 °C for 10 h, and then stirred at 55 °C for 6 h. After the reaction is completed, the solid product is obtained by washing with water, removing impurities and drying. Finally, the obtained solid product is dried in a vacuum oven at 80 °C to obtain the phosphoramide polymer flame retardant.

[0037] The molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:1.2. First, the phosphoramide polymer flame retardant and triglycidyl isocyanurate are put into a pulverizer and mixed evenly. Then, the mixed powder is put into an oven at 125 °C and reacted for 4 h, and then put into an oven at 155 °C and reacted for 4 h to obtain a brown solid, which is the high molecular weight phosphoramide aggregate flame retardant.

[0038] The present invention also provides a transparent flame-retardant composite material, which is prepared by compounding raw materials including a transparent matrix and the high-molecular-weight phosphamide aggregate flame retardant of the present invention. The flame retardant prepared by the present invention can be added to the transparent matrix. The transparent matrix is one or more of TPU, PC, EP, and PET. It can improve the flame retardant performance of the transparent matrix material while maintaining excellent mechanical properties and high light transmittance. Example 5 further details the application of a phosphamide flame retardant provided by the present invention, but the application method of this flame retardant is not limited thereto.

[0039] Example 5

[0040] Add the phosphamide aggregate flame retardant obtained in Example 4 to TPU. First, premix the flame retardant and TPU, and then use a torque rheometer for melt blending to prepare specimens and transparent films with a press (190 °C). The test results of the flame retardant performance and transparency of the obtained materials are shown in Table 1 and Figure 1 .

[0041] Table 1 Mechanical properties, flame retardant properties and transparency of TPU composites

[0042]

[0043]

[0044] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a high molecular weight phosphoramide aggregate flame retardant, characterized in that, The flame retardant is formed by a phosphoramide polymer flame retardant and triglycidyl isocyanurate through a ring-opening reaction between a terminal amino group and an epoxy group; wherein the phosphoramide polymer flame retardant has the following structural formula: Wherein, n is an integer of 15 to 100; and R is an aryloxy group or an aromatic ring.

2. The preparation method of the high molecular weight phosphoramide aggregate flame retardant according to claim 1, characterized in that, The method comprises the following steps: crushing and mixing the phosphoramide polymer flame retardant and triglycidyl isocyanurate uniformly, maintaining the temperature at 120-130°C, kneading for 3-5 hours, then heating to 140-160°C, and continuing kneading for 3-5 hours.

3. The preparation method of the high molecular weight phosphoramide aggregate flame retardant according to claim 2, characterized in that, The molar ratio of the phosphoramide polymer flame retardant to triglycidyl isocyanurate is 3:(1-1.2).

4. The preparation method of the high molecular weight phosphoramide aggregate flame retardant according to claim 1, characterized in that, The phosphoramide polymer flame retardant is prepared by removing hydrochloric acid from phosphoryl dichloride compounds and anhydrous piperazine through solution polycondensation reaction.

5. The preparation method of the high molecular weight phosphamide aggregate flame retardant according to claim 4, wherein The preparation method of the phosphoramide polymer flame retardant specifically comprises: Add anhydrous piperazine and a solvent to an anhydrous and oxygen-free reactor, stir at a temperature of -5°C to 10°C until piperazine is completely dissolved in the solvent, then add triethylamine to the reactor and stir thoroughly; The phosphorus oxychloride compound is dissolved in a solvent, stirred thoroughly and then added dropwise to the reactor, and the temperature of the solution in the reactor is maintained at -5°C to 10°C. After the addition is completed, the reaction temperature is raised to 30°C to 50°C, and the reaction is continued for 5 to 10 hours, and then the temperature is continued to be raised to 55°C to 65°C, and the reaction is continued for 6 to 12 hours. After the reaction is completed, the reactant is washed with water to obtain a crude product, and the crude product is dried to obtain a light yellow solid, which is the phosphoramide polymer flame retardant.

6. The preparation method of the high molecular weight phosphoramide aggregate flame retardant according to claim 5, characterized in that, The solvent is selected from one of dichloromethane, dichloroethane, chloroform, acetonitrile, tetrahydrofuran or N,N-dimethylformamide.

7. The preparation method of the high molecular weight phosphoramide aggregate flame retardant according to claim 5, characterized in that, The phosphorus oxychloride compound is selected from phenyl phosphorus oxychloride and phenyl dichloride phosphate.

8. The preparation method of the high molecular weight phosphamide aggregate flame retardant according to claim 5, characterized in that, The molar ratio of the phosphorus oxychloride compound to anhydrous piperazine is 1:(1-1.5), and the molar ratio of anhydrous piperazine to triethylamine is 1:

2.

9. A phosphoramide aggregate flame retardant, characterized in that, The method is prepared by the method according to any one of claims 1 to 8.

10. A transparent flame-retardant composite material, characterized in that, It comprises a transparent substrate and the phosphoramide aggregate flame retardant as claimed in claim 9, wherein the transparent substrate is one or more of TPU, PC, EP, and PET, and the composite material can maintain mechanical properties and light transmittance while having flame retardant properties.

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