Novel low-water-solubility aromatic sulfonate flame retardant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of arylsulfonate flame retardants, in particular to a novel low-water-solubility arylsulfonate flame retardant and a preparation method and application thereof.According to the preparation method of the arylsulfonate flame retardant, synthesis is conducted in the mode of direct chemical bonding of sulfonic acid groups, traditional sulfonation reaction is avoided, the synthesis process is environmentally friendly, and the yield is high. The molecular structure of the flame retardant contains two symmetrical sulfonate groups, so that the flame retardant shows excellent flame retardance and is low in water solubility; the preparation method has the characteristics of simple and convenient process and easy post-treatment, the obtained product shows insolubility in an organic solvent and can be obtained through direct filtration after synthesis, the cost benefit is remarkable, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of aromatic sulfonate flame retardants, and in particular to a novel low-water-soluble aromatic sulfonate flame retardant and a preparation method and application thereof. Background Art

[0002] Sulfonate flame retardants are non-toxic and highly effective, and have little effect on the transparency and mechanical properties of polycarbonate (PC). Sulfonate flame retardants are the most efficient type of flame retardants used in PC, and generally, a high flame retardant performance can be achieved with an addition amount of less than 1%. Potassium phenylsulfonylbenzenesulfonate (KSS), sodium trichlorophenylsulfonate (STB) and potassium perfluorobutylsulfonate (KPFBS) are typical representatives of sulfonate flame retardants.

[0003] KSS is the most widely used halogen-free sulfonate flame retardant in industrial applications. As a flame retardant additive for polycarbonate (PC), its solubility in water is 25g / 100g water, showing high water solubility, easy to be precipitated from the material by water, and poor flame retardant effect on thin-walled parts. STB is mainly used for opaque PC, but because of the chlorine element in its molecular structure, it has an adverse effect on the environment. The flame retardant efficiency of KPFBS is better than that of KSS. However, long-chain perfluoroalkyl has certain toxicity and bioaccumulation. Although the perfluoroalkyl in KPFBS is in the form of short chains, there are still some concerns in its application. The EU has stipulated the control limit of KPFBS in relevant regulations (REACH), which also limits its use. In addition, the production cost of KPFBS is relatively high.

[0004] It is imperative to develop a new type of halogen-free, environmentally friendly, cheap and high-performance sulfonate flame retardant. Moreover, most of these flame retardants have good water solubility and are easily precipitated by water in the material. How to ensure good flame retardant properties while overcoming the defect of high water solubility is also an important topic in the research of sulfonate flame retardants. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, one of the purposes of the present invention is to provide a method for preparing a novel low water-soluble aromatic sulfonate flame retardant, which is simple to operate, easy to post-process, and convenient to control. The obtained product is insoluble in organic solvents and can be obtained by direct filtration after synthesis. It has significant cost-effectiveness and is suitable for large-scale industrial production.

[0006] The second object of the present invention is to provide a new low water-soluble aromatic sulfonate flame retardant, which is synthesized by direct chemical bonding of sulfonic acid groups, avoiding the traditional sulfonation reaction, and the synthesis process is environmentally friendly. Its molecular structure contains two symmetrical sulfonate groups, showing excellent flame retardant properties, and only 0.02% of the addition amount can achieve UL94 V-0 flame retardant effect at a thickness of 1.6 mm. In addition, after solubility testing, the water solubility of the aromatic sulfonate flame retardant is only 0.4-0.6g / 100g water, indicating that it has extremely low water solubility.

[0007] The third object of the present invention is to provide an application of a novel low water-soluble aromatic sulfonate flame retardant, which is not easily precipitated by water when used in polycarbonate materials and has higher stability. Compared with potassium benzenesulfonylbenzenesulfonate (KSS), the aromatic sulfonate flame retardant of the present invention has lower water solubility and more efficient flame retardancy.

[0008] One of the purposes of the present invention is achieved by the following technical solution: A method for preparing a novel low water-soluble aromatic sulfonate flame retardant comprises the following steps:

[0009] (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.10-1.15, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0;

[0010] (S2), adding activated carbon to the mixed solution, stirring the mixture at 30-100° C. for 0.5-2 h, then filtering the mixture hot, washing the residue with hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution;

[0011] (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution, then cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate;

[0012] (S4), dissolving the aminobenzenesulfonate and pyromellitic dianhydride in an organic solvent, heating to 105-150°C and reflux reacting for 6-12 hours, cooling after the reaction, centrifuging and filtering, taking the filter residue, washing it with an organic solvent for 2-4 times, and then washing it with anhydrous ethanol for 2-4 times, and then drying it to obtain the aromatic sulfonate flame retardant.

[0013] The preparation method of the aromatic sulfonate flame retardant is synthesized by directly chemically bonding sulfonic acid groups, avoiding traditional sulfonation reactions, and the synthesis process is environmentally friendly. Its molecular structure contains two symmetrical sulfonate groups, showing excellent flame retardant properties, and low water solubility. Wherein, steps (S1) and (S2) utilize p-aminobenzenesulfonic acid and alkali to neutralize p-aminobenzenesulfonate solution, and use activated carbon adsorption to remove color, and then in step (S3) the p-aminobenzenesulfonate solution is evaporated and concentrated to form a concentrated solution, so that p-aminobenzenesulfonate crystals are precipitated, and the purity is higher; then in step (S4) and pyromellitic dianhydride are reacted to synthesize the aromatic sulfonate flame retardant insoluble in special organic solvents of the present invention, and after cooling, centrifugal filtration, washing and purification treatment, a high-purity aromatic sulfonate flame retardant is obtained. The preparation method has the characteristics of simple process and easy post-processing. The obtained product shows insolubility in organic solvents, and can be obtained by direct filtration after synthesis, with significant cost-effectiveness, and is suitable for large-scale industrial production.

[0014] Preferably, in the step (S2), the temperature of the hot water is 30-100° C.; and in the step (S3), the relative density of the concentrated liquid is 1.18-1.22.

[0015] By adopting the above technical scheme, washing the filter residue with hot water is more conducive to washing out and utilizing the aminobenzenesulfonate remaining in the filter residue; the relative density of the concentrated solution is controlled at 1.18-1.22 so that the aminobenzenesulfonate can be crystallized and precipitated with higher purity.

[0016] Preferably, in the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

[0017] Preferably, in the step (S4), the drying treatment is carried out at a temperature of 160-190° C. for 4-8 hours.

[0018] Preferably, the base is at least one of potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide.

[0019] Preferably, the amount of activated carbon used is 0.5%-2% of the weight of p-aminobenzenesulfonic acid.

[0020] Preferably, the organic solvent is at least one of toluene, xylene, N,N-dimethylformamide, dimethylacetamide and dimethyl sulfoxide; the mass of the organic solvent required to dissolve p-aminobenzenesulfonate and pyromellitic dianhydride is 60-70 times the mass of pyromellitic dianhydride. The reason for adding so much organic solvent is not because it is insoluble, but because there is an expansion process in the intermediate process. If the amount of solvent is too little, stirring difficulties will occur, which will have an adverse effect on the reaction.

[0021] More preferably, the organic solvent is at least one of N,N-dimethylformamide, dimethylacetamide and dimethyl sulfoxide, so that p-aminobenzenesulfonate and pyromellitic dianhydride are soluble in the organic solvent, while the aryl sulfonate flame retardant is insoluble in the above organic solvent, which makes post-synthesis processing easier and can be obtained by direct filtration after synthesis, which is cost-effective and suitable for large-scale industrial production.

[0022] Preferably, the molar ratio of the p-aminobenzenesulfonate to pyromellitic dianhydride is 2-2.5:1.

[0023] The second object of the present invention is achieved by the following technical solution: a novel low water-soluble aromatic sulfonate flame retardant is prepared by the above-mentioned preparation method of aromatic sulfonate flame retardant, and the structural formula of the aromatic sulfonate flame retardant is as follows:

[0024]

[0025] Where M is K + Or Na + ,

[0026] It should be noted that M mainly depends on the type of base added during the preparation of the aromatic sulfonate flame retardant.

[0027] The third object of the present invention is achieved by the following technical scheme: the application of the above-mentioned aromatic sulfonate flame retardant, the aromatic sulfonate flame retardant is used for flame retardant modified polycarbonate material, and the flame retardant modified polycarbonate material comprises the following raw materials in parts by weight: 98 parts of polycarbonate, 0.1-0.4 parts of aromatic sulfonate flame retardant, 0.1-0.5 parts of anti-dripping agent, 0.1 parts of antioxidant 1010 and 0.2 parts of lubricant PETS.

[0028] The beneficial effects of the present invention are as follows: the preparation method of the novel low water-soluble aromatic sulfonate flame retardant of the present invention is simple to operate, easy to post-process, and convenient to control; the obtained product is insoluble in organic solvents, can be obtained by direct filtration after synthesis, has significant cost-effectiveness, and is suitable for large-scale industrial production.

[0029] The novel low water-soluble aromatic sulfonate flame retardant of the present invention is synthesized by directly chemically bonding sulfonic acid groups, avoiding the traditional sulfonation reaction, and the synthesis process is environmentally friendly. Its molecular structure contains two symmetrical sulfonate groups, showing excellent flame retardant properties, and only 0.02% of the addition amount can achieve UL94 V-0 flame retardant effect at a thickness of 1.6 mm. In addition, after solubility testing, the water solubility of the aromatic sulfonate flame retardant is only 0.4-0.6g / 100g water, indicating that it has extremely low water solubility.

[0030] The novel low water-soluble aromatic sulfonate flame retardant of the present invention is not easily precipitated by water when used in polycarbonate materials and has higher stability. Compared with potassium benzenesulfonylbenzenesulfonate (KSS), the aromatic sulfonate flame retardant of the present invention has lower water solubility and more efficient flame retardancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the infrared spectrum of the aromatic sulfonate flame retardant of Example 1;

[0032] Figure 2 It is the TGA curve chart of the aromatic sulfonate flame retardant of Example 1. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0034] Example 1

[0035] A method for preparing a novel low water-soluble aromatic sulfonate flame retardant comprises the following steps:

[0036] (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.12, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0;

[0037] (S2), adding activated carbon to the mixed solution, stirring the mixture at 70° C. for 1 h, and then filtering the mixture hot, washing the residue with 70° C. hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution;

[0038] (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution with a relative density of 1.18, then cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate;

[0039] (S4) Evenly mix the aminobenzenesulfonate, pyromellitic dianhydride and organic solvent, heat to 120°C and reflux for reaction for 8 hours. After the reaction is completed, cool and centrifuge to obtain the residue, wash it 3 times with an organic solvent, then wash it 3 times with anhydrous ethanol, and then dry it at 160°C for 6 hours to obtain the aromatic sulfonate flame retardant.

[0040] The molar ratio of the aminobenzenesulfonate to pyromellitic anhydride is 2.2:1; the mass of the organic solvent required to dissolve the aminobenzenesulfonate and pyromellitic anhydride is 65 times the mass of pyromellitic anhydride.

[0041] In the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

[0042] The base is potassium hydroxide.

[0043] The amount of the activated carbon used is 1% of the weight of p-aminobenzenesulfonic acid.

[0044] The organic solvent is N,N-dimethylformamide.

[0045] Example 2

[0046] A method for preparing a novel low water-soluble aromatic sulfonate flame retardant comprises the following steps:

[0047] (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.10, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0;

[0048] (S2), adding activated carbon to the mixed solution, stirring the mixture at 50° C. for 2 h, and then filtering the mixture hot, washing the residue with 50° C. hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution;

[0049] (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution with a relative density of 1.18, then cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate;

[0050] (S4) Evenly mix the aminobenzenesulfonate, pyromellitic dianhydride and organic solvent, heat to 105°C and reflux for 12 hours. After the reaction is completed, cool and centrifuge to obtain the residue, wash it 3 times with an organic solvent, then wash it 3 times with anhydrous ethanol, and then dry it at 160°C for 8 hours to obtain the aromatic sulfonate flame retardant.

[0051] The molar ratio of the p-aminobenzenesulfonate and pyromellitic anhydride is 2:1; the mass of the organic solvent required to dissolve the p-aminobenzenesulfonate and pyromellitic anhydride is 60 times the mass of pyromellitic anhydride.

[0052] In the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

[0053] The base is sodium hydroxide.

[0054] The amount of the activated carbon used is 0.5% of the weight of p-aminobenzenesulfonic acid.

[0055] The organic solvent is N,N-dimethylformamide.

[0056] Example 3

[0057] A method for preparing a novel low water-soluble aromatic sulfonate flame retardant comprises the following steps:

[0058] (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.15, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0;

[0059] (S2), adding activated carbon to the mixed solution, stirring the mixture at 90° C. for 0.5 h, then filtering the mixture hot, washing the residue with 90° C. hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution;

[0060] (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution with a relative density of 1.18, cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate;

[0061] (S4) Evenly mix the aminobenzenesulfonate, pyromellitic dianhydride and organic solvent, heat to 150°C and reflux for reaction for 6 hours. After the reaction is completed, cool and centrifuge to obtain the residue, wash it 3 times with an organic solvent, then wash it 3 times with anhydrous ethanol, and then dry it at 190°C for 4 hours to obtain the aromatic sulfonate flame retardant.

[0062] The molar ratio of the aminobenzenesulfonate to pyromellitic anhydride is 2.5:1; the mass of the organic solvent required to dissolve the aminobenzenesulfonate and pyromellitic anhydride is 70 times the mass of pyromellitic anhydride.

[0063] In the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

[0064] The base is potassium hydroxide.

[0065] The amount of the activated carbon used is 2% of the weight of p-aminobenzenesulfonic acid.

[0066] The organic solvent is N,N-dimethylformamide.

[0067] Example 4

[0068] A method for preparing a novel low water-soluble aromatic sulfonate flame retardant comprises the following steps:

[0069] (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.14, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0;

[0070] (S2), adding activated carbon to the mixed solution, stirring the mixture at 60° C. for 1 h, then hot filtering, washing the residue with 60° C. hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution;

[0071] (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution with a relative density of 1.18, cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate;

[0072] (S4) Evenly mix the aminobenzenesulfonate, pyromellitic dianhydride and organic solvent, heat to 110°C and reflux for reaction for 8 hours. After the reaction is completed, cool and centrifuge to obtain the residue, wash it 3 times with an organic solvent, then wash it 3 times with anhydrous ethanol, and then dry it at 180°C for 6 hours to obtain the aromatic sulfonate flame retardant.

[0073] The molar ratio of the aminobenzenesulfonate and pyromellitic anhydride is 2.3:1; the mass of the organic solvent required to dissolve the aminobenzenesulfonate and pyromellitic anhydride is 66 times the mass of pyromellitic anhydride.

[0074] In the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

[0075] The base is sodium hydroxide.

[0076] The amount of the activated carbon used is 1% of the weight of p-aminobenzenesulfonic acid.

[0077] The organic solvent is N,N-dimethylformamide.

[0078] Comparative Example 1

[0079] A sulfonate flame retardant is potassium benzenesulfonylbenzenesulfonate (KSS).

[0080] Performance Test:

[0081] I. Take the aromatic sulfonate flame retardant of Example 1 and use an infrared spectrometer to detect it. The infrared spectrum is as follows Figure 1 As shown in the spectrum, the wave number is 1784cm -1 、1724cm -1 、1391cm -1 and 725cm -1 It is the characteristic peak of the benzoimide structure, with a wave number of 1203 cm -1 It is the characteristic peak of sulfonate S=O, which shows that the preparation method of aromatic sulfonate flame retardant in Example 1 is successfully synthesized, feasible and effective.

[0082] II. Take the aromatic sulfonate flame retardant of Example 1 and use a thermogravimetric analyzer to measure the TGA curve. Figure 2 As shown in the TGA curve, it can be seen that the T max The temperature (referring to the temperature corresponding to the maximum degradation rate) is 530.2℃, which is consistent with the T maxThe temperature is very close to 531℃. During the action of flame retardant, the flame retardant and its degradation products interact with the degradation intermediates of the matrix material. max T of the base material max The smaller the difference, the better the overall flame retardancy. The reason is that the closer the temperature is to the maximum decomposition rate, the greater the possibility that the main intermediate products will exist at the same time or contact each other, and the easier it is to achieve the purpose of flame retardancy. The flame retardant mechanism is referenced in the literature "Synthesis of Silane Sulfonate Flame Retardant and Its Application in Polycarbonate_Lu Xiaodong", "Nodera A, Kanai T. Thermal decomposition behavior and flame retardancy of polycarbonate containing organic metal salts: Effect of salt composition [J]. Journal of Applied Polymer Science, 2004, 94 (5): 2131-2139.".

[0083] III. Flame retardant application test, modifying polycarbonate according to the ingredients in Table 1:

[0084]

[0085] In each of the above test groups, the raw materials were dispersed and mixed, and then melted, mixed, extruded, cooled, pelletized, and the like by a twin-screw extruder, and the pellets were dried to obtain a flame-retardant modified polycarbonate material;

[0086] Among them, the temperature of each zone of the twin-screw extruder is set as: zone 1 240-250℃, zone 2 260-270℃, zone 3 260-270℃, zone 4 260-270℃, zone 5 250-260℃, zone 6 240-250℃, zone 7 230-240℃, zone 8 220-230℃, head temperature 220-230℃; vacuum is controlled at -0.07MPa.

[0087] The prepared flame retardant modified polycarbonate material was injection molded into a standard test specimen, and a flame retardant test was performed according to the UL94 vertical burning test method (sample thickness 1.6 mm). The test results are shown in Table 2 below:

[0088]

[0089]

[0090] It can be seen from Table 2 above that the flame retardant modification of polycarbonate using the aromatic sulfonate flame retardant of the present application, even if the prepared sample is boiled and then dried, the measured flame retardant data is still very stable, indicating that the aromatic sulfonate flame retardant of the present application is not precipitated from the sample during boiling, and its flame retardant effect is significant.

[0091] IV. Take the aromatic sulfonate flame retardant of Example 1 and the sulfonate flame retardant of Comparative Example 1, and conduct water solubility test. The test method is: weigh a certain amount of deionized water, add an excess of flame retardant to make it a supersaturated solution, and keep the solution temperature at 25°C, filter, weigh the mass of the filtrate as m, and weigh the mass of the residual solid after evaporating the filtrate as n. The solubility in water is n / (mn)*100, and the unit is g / 100g water. The test results are shown in Table 3 below:

[0092] Water solubility (g / 100g water) Example 1 0.5 Comparative Example 1 25

[0093] It can be seen from Table 3 above that the water solubility of the aromatic sulfonate flame retardant of Example 1 is only 0.5 g / 100 g water, indicating that it has extremely low water solubility.

[0094] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A method for preparing a novel low water-soluble aromatic sulfonate flame retardant, characterized in that: The steps include: (S1), dissolving p-aminobenzenesulfonic acid in water, adjusting the relative density of the system to 1.10-1.15, and then adding alkali to prepare a mixed solution with a pH of 7.0-8.0; (S2), adding activated carbon to the mixed solution, stirring the mixture at 30-100° C. for 0.5-2 h, then filtering the mixture hot, washing the residue with hot water, and taking the filtrate to obtain a p-aminobenzenesulfonate solution; (S3), evaporating and concentrating the aminobenzenesulfonate solution to form a concentrated solution, then cooling and crystallizing, centrifuging and filtering, taking the filter residue, and drying to obtain the aminobenzenesulfonate; (S4), dissolving the aminobenzenesulfonate and pyromellitic dianhydride in an organic solvent, heating to 105-150°C and reflux reacting for 6-12 hours, cooling after the reaction, centrifuging and filtering, taking the filter residue, washing it with an organic solvent for 2-4 times, and then washing it with anhydrous ethanol for 2-4 times, and then drying it to obtain the aromatic sulfonate flame retardant.

2. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: In the step (S2), the temperature of the hot water is 30-100°C; in the step (S3), the relative density of the concentrated liquid is 1.18-1.

22.

3. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: In the step (S3), the filtrate from the centrifugal filtration is recovered and recycled; in the step (S4), the filtrate from the centrifugal filtration and washing is recovered and recycled.

4. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: In the step (S4), the drying condition is drying at 160-190° C. for 4-8 hours.

5. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: The alkali is at least one of potassium carbonate, potassium bicarbonate, potassium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide.

6. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: The amount of the activated carbon used is 0.5%-2% of the weight of p-aminobenzenesulfonic acid.

7. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: The organic solvent is at least one of toluene, xylene, N,N-dimethylformamide, dimethylacetamide and dimethyl sulfoxide; the mass of the organic solvent required to dissolve p-aminobenzenesulfonate and pyromellitic dianhydride is 60-70 times the mass of pyromellitic dianhydride.

8. The method for preparing a novel low water-soluble aromatic sulfonate flame retardant according to claim 1, characterized in that: The molar ratio of the p-aminobenzenesulfonate to pyromellitic dianhydride is 2-2.5:

1.

9. A novel low water-soluble aromatic sulfonate flame retardant, characterized in that: The aromatic sulfonate flame retardant is prepared by the preparation method of the aromatic sulfonate flame retardant according to any one of claims 1 to 8, and the structural formula of the aromatic sulfonate flame retardant is as follows: Where M is K + Or Na + .

10. A use of the aromatic sulfonate flame retardant according to claim 9, characterized in that: The aromatic sulfonate flame retardant is used for flame retardant modified polycarbonate materials.

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