Phosphorus-containing intrinsic flame-retardant epoxy resin, preparation method and application thereof

Abstract

The application discloses a kind of phosphorus-containing intrinsic flame-retardant epoxy resin and its preparation method and application, and flame-retardant epoxy resin includes epoxy phosphate, or epoxy pyrophosphate, or epoxy triphosphate, and its corresponding solidification product.The application is reacted with epoxy resin respectively using phosphoric acid, pyrophosphoric acid, triphosphoric acid, and phosphoric acid, pyrophosphoric acid, triphosphoric acid is introduced into the molecular structure of epoxy resin, and three kinds of phosphorus-containing epoxy resin, epoxy phosphate (EP-PI), epoxy pyrophosphate (EP-PPI) and epoxy triphosphate (EP-PPA) are prepared, and the reaction condition is mild and can realize higher phosphorus content, greater range of phosphorus content control.When the molar ratio of epoxy resin and phosphoric acid (pyrophosphoric acid, polyphosphoric acid) is only 20:1, the obtained solidification product can show good flame-retardant, smoke suppression performance.

Description

Technical Field

[0001] The present invention belongs to the field of flame-retardant epoxy resin compositions, and in particular relates to a phosphorus-containing intrinsic flame-retardant epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin (EP), an important thermosetting material, boasts excellent physical, mechanical, and electrical insulation properties, excellent adhesion to various materials, and flexible processing. It is widely used in electronics, coatings, adhesives, fiber-reinforced composites, and other fields. However, pure epoxy resin has a limiting oxygen index (LOI) of approximately 23%, making it susceptible to combustion in air. This releases significant amounts of heat and harmful gases, accompanied by the release of high-temperature molten material. This poses a significant risk to human life and property, significantly limiting its application. Therefore, imparting flame retardancy to epoxy resin is crucial.

[0003] Generally speaking, epoxy resin flame retardancy methods can be categorized into two main types: additive and reactive. Additive flame retardant epoxy resins involve mechanically mixing flame retardants containing elements such as phosphorus, silicon, nitrogen, and carbon into the epoxy resin, without any chemical reaction between the flame retardant additive and the epoxy resin. Common additive flame retardants for epoxy resins include red phosphorus, silicon dioxide, ammonium polyphosphate, hydrotalcite, inorganic hydroxides, and inorganic oxides. This method offers significant advantages such as simple processing and low cost, but also has disadvantages such as uneven dispersion of the flame retardant, easy migration, and poor compatibility between the matrix and the flame retardant.

[0004] Reactive flame retardancy, also known as intrinsic flame retardancy, involves introducing flame-retardant monomers into the polymer structure through covalent bonds or other means, overcoming the shortcomings of additive flame retardants, such as poor dispersibility, compatibility, and easy migration. Intrinsically flame-retardant epoxy resins are made by introducing flame-retardant functional groups or elements (such as Cl, Br, N, P, and Si) into epoxy-containing resins during synthesis or later through chemical methods, imparting flame retardancy. However, while the introduction of halogens, such as Cl and Br, can produce good flame retardancy, they produce highly toxic, carcinogenic, and corrosive gases such as hydrogen halides, brominated furans, and dioxins during combustion, which can harm the environment and human health and have been banned in countries such as the European Union. Therefore, the current method for preparing halogen-free intrinsic flame-retardant epoxy resins primarily involves the introduction of elements such as P, N, and Si. The advantages of this method are that the flame-retardant elements are not easily migrated out, good compatibility, minimal impact on the mechanical properties of the epoxy resin, and excellent flame retardancy can be achieved with a small amount of flame retardant. However, the disadvantages are complex processing and high cost.

[0005] Among the flame-retardant elements or groups mentioned above, phosphorus-based flame retardants play a key role in halogen-free flame retardants due to their numerous advantages, including abundant resources, low smoke emissions, low toxicity, chemical versatility, multiple flame-retardant mechanisms, and high flame-retardant efficiency. The use of phosphorus-based flame retardants can be divided into two types: additive and reactive. Additive phosphorus-based flame retardants include inorganic phosphorus compounds such as phosphates, ammonium polyphosphate, and red phosphorus, as well as organic phosphorus compounds such as alkyl (aryl) phosphates, phosphites, phosphazenes, and phosphorus-containing Schiff bases. Reactive phosphorus-based flame retardants are further divided into two categories: phosphorus-containing curing agents and phosphorus-containing epoxy resins. The former involves adding a curing agent containing a flame-retardant structure to an epoxy resin matrix and using it to cure the epoxy resin. The cured epoxy resin exhibits excellent flame retardant properties. The latter, on the other hand, is formed by the direct polymerization of monomers containing the flame retardant. Among these, phosphaphenanthrene flame retardants, represented by DOPO, are the most typical. Typically, DOPO or its derivatives are introduced into the epoxy resin chain through a chain extension reaction, a complex process and demanding reaction conditions. Furthermore, regulating the phosphorus content in epoxy resins is difficult, requiring front-end reaction design to construct more complex DOPO derivatives.

[0006] In view of the problems of harsh reaction conditions and difficulty in adjusting the phosphorus content in the intrinsic flame-retardant epoxy resin introduced by chain extension reaction, it is urgent to propose a phosphorus-containing intrinsic flame-retardant epoxy resin with mild reaction conditions and the ability to achieve higher phosphorus content and a wider range of phosphorus content control. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a phosphorus-containing intrinsic flame retardant epoxy resin with simple process, low cost and good flame retardant effect, as well as a preparation method and application thereof.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] In a first aspect, the present invention provides a phosphorus-containing intrinsic flame-retardant epoxy resin comprising epoxy phosphate, epoxy pyrophosphate, or epoxy tripolyphosphate, and corresponding cured products thereof.

[0010] In a second aspect, the present invention provides a method for preparing the phosphorus-containing intrinsic flame retardant epoxy resin as described above, comprising the following steps:

[0011] S1. Add a certain amount of bisphenol A epoxy resin to a solvent, heat it, and stir it to dissolve it to obtain solution A;

[0012] S2. Weigh a corresponding amount of inorganic phosphoric acid and dissolve it in the same solvent to obtain solution B;

[0013] S3, mixing solution A and solution B in a reaction vessel, continuously stirring and refluxing to react, to obtain solution C;

[0014] S4, removing the solvent in solution C to obtain product D.

[0015] Further, in step S1, the solvent is a mixture of one or more of acetone, methyl ketone, ethyl ketone, cyclohexanone, ethyl acetate, toluene, xylene, anhydrous ethanol, ethylene glycol;

[0016] Preferably, when the solvent is acetone, the ratio of the epoxy resin to acetone is 1 g:2.5 mL.

[0017] Further, in step S2:

[0018] The inorganic phosphoric acid is phosphoric acid (PI), pyrophosphoric acid (PPI) or tripolyphosphoric acid (PPA);

[0019] The corresponding reaction equations are shown as follows, respectively:

[0020]

[0021] Preferably, the molar ratio of the epoxy resin to the inorganic phosphoric acid is 5-70:1.

[0022] Further, in step S3, the reaction temperature is 55-70°C and the reaction time is 2.5-4.5 h.

[0023] Further, in step S3, solution B is slowly added to solution A under continuous stirring.

[0024] In a third aspect, the present application provides an application of the phosphorus-containing intrinsic flame-retardant epoxy resin as described above, comprising the following steps:

[0025] S01, placing the flame-retardant epoxy resin in a dry container and heating and stirring until completely melted;

[0026] S02, adding a curing agent to the melt and strongly stirring until the curing agent is completely and uniformly mixed;

[0027] S03, placing the above mixture in a vacuum drying box to perform vacuum deaeration;

[0028] S04, after the deaeration is completed, pouring the mixture into a preheated mold to prepare a sample and placing it in a vacuum drying box for curing;

[0029] S05, cooling and demolding after the curing is completed to obtain a cured product.

[0030] Further, in step S02:

[0031] The curing agent is 4,4'-diaminodiphenyl methane (DDM);

[0032] The curing agent was added in batches within 5 minutes.

[0033] Furthermore, in step S03:

[0034] Vacuum drying temperature is 100-130°C;

[0035] The vacuum drying time should not exceed 5 minutes.

[0036] Furthermore, in step S04, the curing process is: baking at 120° C. for 2 hours, then heating to 150° C. and baking for another 2 hours.

[0037] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0038] (1) The present invention introduces phosphoric acid, pyrophosphoric acid, and tripolyphosphoric acid into the molecular structure of epoxy resin to achieve intrinsic flame retardant epoxy resin with controllable phosphorus content. The reaction conditions are mild, and the reaction temperature is only 55-70°C, which is simpler than the chain extension reaction at about 160°C and requiring a catalyst.

[0039] (2) The phosphorus-containing epoxy resin prepared by the present invention can achieve a higher phosphorus content and a wider range of phosphorus content control;

[0040] (3) The phosphorus-containing intrinsic flame-retardant epoxy resin of the present invention exhibits excellent flame retardancy and smoke suppression properties when only 1 / 20 or 1 / 40 of the epoxy resin reacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an undue limitation of the present invention. Obviously, the drawings described below are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive effort. In the accompanying drawings:

[0042] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of Preparation Example 1.

[0043] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of Preparation Example 2.

[0044] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of Preparation Example 3.

[0045] Figure 4 HRR curves of pure EP and phosphorus-containing epoxy resin cured products.

[0046] Figure 5 These are the THR curves of pure EP and phosphorus-containing epoxy resin cured products.

[0047] Figure 6 These are the SPR curves of pure EP and phosphorus-containing epoxy resin cured products.

[0048] Figure 7 These are the TSP curves of pure EP and phosphorus-containing epoxy resin cured products.

[0049] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0051] It should be noted that the bisphenol A epoxy resin described in the present invention includes various types, such as E-44, E-42, E-51, E-55, etc., and this specification takes E44 as an example for explanation; the solvent of the reaction system includes but is not limited to a mixture of one or more of acetone, ketone, ethyl ketone, cyclohexanone, ethyl acetate, toluene, xylene, anhydrous ethanol, and ethylene glycol, and this specification takes acetone as an example.

[0052] Preparation Example 1

[0053] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the temperature was raised to 65° C. and stirred to dissolve to obtain an epoxy resin-acetone solution; 40.60 g of phosphoric acid solution was then weighed, 80 mL of acetone was added, and stirred to obtain a phosphoric acid-acetone solution; under continuous stirring, the phosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 65° C. for 4.5 hours; the acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PI; the epoxy group conversion rate of the sample was measured according to the national standard GB / T-1677, and the H NMR spectrum was as follows: Figure 1 shown.

[0054] Preparation Example 2

[0055] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the temperature was raised to 55° C. and stirred to dissolve, thereby obtaining an epoxy resin-acetone solution. 62.73 g of pyrophosphoric acid was then weighed, 100 mL of acetone was added, and stirred to obtain a pyrophosphoric acid-acetone solution. Under continuous stirring, the pyrophosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 55° C. for 3 h. The acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PPI. The epoxy group conversion rate of the sample was measured according to the national standard GB / T-1677, and the H NMR spectrum showed that it was 97.5%. Figure 2 shown.

[0056] Preparation Example 3

[0057] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the mixture was heated to 70° C. and stirred to dissolve to obtain an epoxy resin-acetone solution. 119.12 g of tripolyphosphoric acid was then weighed, 120 mL of acetone was added, and stirred to obtain a tripolyphosphoric acid-acetone solution. Under continuous stirring, the tripolyphosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 70° C. for 2.5 h. The acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PPA. The epoxy group conversion rate of the sample was measured according to the national standard GB / T-1677, and the H NMR spectrum was as follows: Figure 3 shown.

[0058] Preparation Example 4

[0059] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the temperature was raised to 65° C. and stirred to dissolve it to obtain an epoxy resin-acetone solution; 1.02 g of phosphoric acid solution was then weighed, 10 mL of acetone was added, and stirred to obtain a phosphoric acid-acetone solution; under continuous stirring, the phosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 65° C. for 4.5 hours; the acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PI (20:1).

[0060] Preparation Example 5

[0061] Weigh 80.00 g of bisphenol A epoxy resin E44, add 200 mL of acetone, heat to 55° C. and stir to dissolve it to obtain an epoxy resin-acetone solution; then weigh 1.57 g of pyrophosphoric acid, add 10 mL of acetone and stir to obtain a pyrophosphoric acid-acetone solution; under continuous stirring, slowly add the pyrophosphoric acid-acetone solution to the epoxy resin-acetone solution, and reflux at 55° C. for 3 hours; remove the acetone solvent by rotary evaporation to obtain a sample labeled EP-PPI (20:1).

[0062] Preparation Example 6

[0063] Weigh 80.00 g of bisphenol A epoxy resin E44, add 200 mL of acetone, heat to 70° C. and stir to dissolve it to obtain an epoxy resin-acetone solution; then weigh 2.98 g of tripolyphosphoric acid, add 10 mL of acetone and stir to obtain a tripolyphosphate-acetone solution; under continuous stirring, slowly add the tripolyphosphate-acetone solution to the epoxy resin-acetone solution, and reflux at 70° C. for 2.5 hours; remove the acetone solvent by rotary evaporation to obtain a sample labeled EP-PPA (20:1).

[0064] Preparation Example 7

[0065] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the temperature was raised to 65° C. and stirred to dissolve it to obtain an epoxy resin-acetone solution; 0.51 g of phosphoric acid solution was then weighed, 5 mL of acetone was added, and stirred to obtain a phosphoric acid-acetone solution; under continuous stirring, the phosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 65° C. for 4.5 hours; the acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PI (40:1).

[0066] Preparation Example 8

[0067] Weigh 80.00 g of bisphenol A epoxy resin E44, add 200 mL of acetone, heat to 55° C. and stir to dissolve it to obtain an epoxy resin-acetone solution; then weigh 0.78 g of pyrophosphoric acid, add 5 mL of acetone and stir to obtain a pyrophosphoric acid-acetone solution; under continuous stirring, slowly add the pyrophosphoric acid-acetone solution to the epoxy resin-acetone solution, and reflux at 55° C. for 3 hours; remove the acetone solvent by rotary evaporation to obtain a sample labeled EP-PPI (40:1).

[0068] Preparation Example 9

[0069] 80.00 g of bisphenol A epoxy resin E44 was weighed, 200 mL of acetone was added, and the temperature was raised to 70° C. and stirred to dissolve it to obtain an epoxy resin-acetone solution; 1.49 g of tripolyphosphoric acid was then weighed, 5 mL of acetone was added, and stirred to obtain a tripolyphosphoric acid-acetone solution; under continuous stirring, the tripolyphosphoric acid-acetone solution was slowly added to the epoxy resin-acetone solution, and the mixture was refluxed at 70° C. for 2.5 hours; the acetone solvent was removed by rotary evaporation to obtain a sample labeled EP-PPA (40:1).

[0070] Example 1

[0071] 80g of EP-PI (20:1), EP-PPI (20:1), and EP-PPA (20:1) were weighed separately and added to a dry beaker, and stirred at 90°C until completely melted; 16.57g of curing agent 4,4'-diaminodiphenylmethane (DDM) was added to the melt in batches within 5 minutes, and stirred vigorously until the curing agent was completely mixed; the above mixture was placed in a vacuum drying oven at 120°C and vacuumed (no more than 5 minutes) to complete the defoaming work; the mixed slurry was then poured into a preheated mold to prepare a specimen, and placed in a vacuum drying oven for curing: baked at 120°C for 2h, then heated to 150°C and baked for another 2h; after curing, it was slightly cooled and demolded to obtain EP-PI (20:1), EP-PPI (20:1), and EP-PPA (20:1) cured products.

[0072] The EP-PI (20:1), EP-PPI (20:1), and EP-PPA (20:1) were prepared according to Preparation Examples 4, 6, and 8, respectively.

[0073] Example 2

[0074] 80g of EP-PI (40:1), EP-PPI (40:1), and EP-PPA (40:1) were weighed separately and added to a dry beaker, and stirred at 90°C until completely melted; 17.01g of curing agent DDM was added to the melt in batches within 5 minutes, and stirred vigorously until the curing agent was completely mixed; the above mixture was placed in a vacuum drying oven at 120°C and vacuumed (no more than 5 minutes) to complete the defoaming work; the mixed slurry was then poured into a preheated mold to prepare a specimen, and placed in a vacuum drying oven for curing: bake at 120°C for 2h, then heat to 150°C and bake for another 2h; after curing is completed, cool slightly and demold to obtain EP-PI (40:1), EP-PPI (40:1), and EP-PPA (40:1) cured products.

[0075] The EP-PI (40:1), EP-PPI (40:1), and EP-PPA (40:1) were prepared according to Preparation Examples 5, 7, and 9, respectively.

[0076] Comparative Example 1

[0077] Weigh 80g of bisphenol A epoxy resin E44 into a dry beaker and stir at 90°C until completely melted; add 17.45g of curing agent DDM to the melt in batches over 5 minutes and stir vigorously until the curing agent is completely mixed; place the above mixture in a vacuum drying oven at 120°C and evacuate (no more than 5 minutes) to complete the degassing work; then pour the mixed slurry into a preheated mold to prepare a specimen, and place it in a vacuum drying oven for curing: bake at 120°C for 2 hours, then increase the temperature to 150°C and bake for another 2 hours; after curing is complete, cool slightly and demold to obtain the EP cured product.

[0078] Test Example 1: Determination of flame retardant properties of soft PVC / MHEPE composite materials

[0079] (1) Test method:

[0080] The seven cured products prepared in Examples 1-2 and Comparative Example 1 were tested for LOI, heat release rate (HRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP). The following measurement methods were used: LOI was measured according to the test conditions and procedures specified in GB / T 2406.2-2009, "Determination of Combustion Behavior of Plastics by Oxygen Index Method," using a sample size of 80 mm × 10 mm × 4 mm. The remaining parameters were measured according to the test conditions and procedures specified in GB / T 16172-2007, "Test Method for Heat Release Rate of Building Materials," using a sample size of 100 mm × 100 mm × 3 mm and an irradiation intensity of 35 kW / m².

[0081] (2) Test results:

[0082] The LOI values ​​of the above 7 kinds of cured products are shown in Table 1; the comparison of HRR and THR curves is shown in Figure 4 and Figure 5 As shown; SPR and TSP curves are shown Figure 6 and Figure 7 shown.

[0083] As can be seen from Table 1, the LOI values ​​of the six cured products of EP-PI (20:1), EP-PI (40:1), EP-PPI (20:1), EP-PPI (40:1), EP-PPA (20:1), and EP-PPA (40:1) are all greater than that of pure EP. Figure 4 and Figure 5It can be seen that the HRR and THR of the six cured products are all lower than those of pure EP. Taking EP-PPA (40:1) as an example, its LOI value, peak HRR, and THR values ​​are 32.33%, 462.99 kW / m², and 98.7 MJ / m², respectively. Compared with pure EP, these values ​​are 31.96% higher, 46.54% lower, and 13.05% lower, respectively. This means that excellent flame retardancy can be achieved with only 1 / 40 of the EP-PPA content.

[0084]

[0085] Table 1

[0086] Depend on Figure 6 and Figure 7 It can be seen that the SPR and TSP values ​​of the six cured products—EP-PI (20:1), EP-PI (40:1), EP-PPI (20:1), EP-PPI (40:1), EP-PPA (20:1), and EP-PPA (40:1)—are all lower than those of pure EP. Taking EP-PPA (40:1) as an example, its peak SPR and TSP are 0.1114 m² / s and 22.8 m², respectively, which are 66.87% and 50.97% lower than those of pure EP, demonstrating excellent smoke suppression performance.

[0087] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments of equivalent changes using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. The implementation schemes in the above-mentioned embodiments can also be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above-mentioned embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A phosphorus-containing intrinsic flame-retardant epoxy resin, characterized in that: The invention comprises epoxy phosphate, epoxy pyrophosphate, or epoxy tripolyphosphate, and the corresponding cured product, and the preparation method thereof comprises the following steps: S1. Add a certain amount of bisphenol A epoxy resin to a solvent, heat it, and stir it to dissolve it to obtain solution A; S2. Weigh a corresponding amount of inorganic phosphoric acid and dissolve it in the same solvent to obtain solution B; S3, mixing solution A and solution B in a reaction vessel, continuously stirring and refluxing to react, to obtain solution C; S4, removing the solvent from solution C to obtain product D; The inorganic phosphoric acid is phosphoric acid, pyrophosphoric acid or tripolyphosphoric acid; The molar ratio of the epoxy resin to the inorganic phosphoric acid is 5 to 70:

1.

2. The phosphorus-containing intrinsic flame-retardant epoxy resin according to claim 1, characterized in that: In step S1: The solvent is a mixture of one or more of acetone, ketone, ethyl ketone, cyclohexanone, ethyl acetate, toluene, xylene, anhydrous ethanol, and ethylene glycol.

3. The phosphorus-containing intrinsic flame-retardant epoxy resin according to claim 2, wherein: When the solvent is acetone, the ratio of epoxy resin to acetone is 1 g:2.5 mL.

4. The phosphorus-containing intrinsic flame-retardant epoxy resin according to claim 1, wherein: In step S3, the reaction temperature is 55-70° C., and the reaction time is 2.5-4.5 h.

5. The phosphorus-containing intrinsic flame-retardant epoxy resin according to claim 1, wherein: In step S3, solution B is slowly added to solution A under continuous stirring.

6. An application of the phosphorus-containing intrinsic flame-retardant epoxy resin according to claim 1, characterized in that: The following steps are involved: S01. Place the flame retardant epoxy resin in a dry container and heat and stir until it is completely melted; S02. Add curing agent to the melt and stir vigorously until the curing agent is completely mixed; S03, placing the above mixture in a vacuum drying oven and evacuating the air to remove bubbles; S04. After degassing, the mixture is poured into a preheated mold to prepare a specimen, which is then placed in a vacuum drying oven for curing; S05, after curing is completed, cooling and demoulding are performed to obtain a solidified product.

7. The use of the phosphorus-containing intrinsic flame retardant epoxy resin according to claim 6, characterized in that: In step S02: The curing agent is 4,4'-diaminodiphenylmethane; The curing agent was added in batches within 5 minutes.

8. The use of the phosphorus-containing intrinsic flame retardant epoxy resin according to claim 6, characterized in that: In step S03: Vacuum drying temperature is 100-130°C; The vacuum drying time should not exceed 5 minutes.

9. The use of the phosphorus-containing intrinsic flame retardant epoxy resin according to claim 6, characterized in that: In step S04, the curing process is: baking at 120° C. for 2 hours, then heating to 150° C. and baking for another 2 hours.

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