Flame-retardant phenolic resin molding material and preparation method thereof

Abstract

The invention discloses a flame-retardant phenolic resin molding material and a preparation method thereof. The flame-retardant phenolic resin molding material comprises the following raw materials in parts by weight: 60-70 parts of modified phenolic resin, 10-15 parts of epoxy resin, 15-20 parts of inorganic filler, 30-35 parts of organic filler, 1.5-2.5 parts of a release agent, 5-8 parts of a curing agent, 3-4 parts of a curing aid and 1-2 parts of a coloring agent. According to the synthesized modified phenolic resin, silicon is introduced through a silicon etherification reaction of phenolic hydroxyl groups in the phenolic resin, so that the flame retardant property and the oxidation resistance of a molding material are improved, the consumption of the phenolic hydroxyl groups is reduced, and the aging resistance of the molding material is improved. Meanwhile, a DOPO structure is introduced into the resin, so that migration of the additive flame retardant is avoided, and the flame retardant property of the molding material can be fully exerted. And a flexible alkane long straight chain is introduced into the resin, so that the flexibility of the resin is improved, and the toughness and machinability of the molding material are improved.

Description

Technical Field

[0001] The present invention relates to the field of molding materials, and specifically relates to a flame-retardant phenolic resin molding material and a preparation method thereof. Background Art

[0002] Phenolic resin molding materials are materials with excellent balance in mechanical strength, heat resistance, dimensional accuracy, and cost. Therefore, phenolic resin molding materials are widely used in various fields. Among them, due to their excellent electrical insulation and heat resistance, they are also used in electronic parts such as coil bobbins. Flame retardancy is required when used in electronic parts. From an environmental protection perspective, adding flame retardants such as red phosphorus and organic phosphorus compounds can endow phenolic resin molding materials with flame retardant properties. However, additive flame retardants have disadvantages such as small molecules being prone to migration, insufficient dispersion in the resin, and excessive addition amount damaging the mechanical properties of the resin molding material.

[0003] The disadvantages of phenolic resin are determined by its molecular structure. The phenolic hydroxyl group in phenol, the reactant for synthesizing phenolic resin, which is prone to oxidation, will be retained during the resin synthesis process, and then the methylene group formed by condensation with formaldehyde is also prone to oxidation, so it affects the heat resistance of phenolic resin; in addition, phenolic resin is formed by a large number of highly rigid benzene rings connected to each other through methylene groups, which is a molecular structure with high cross-linking density and difficult internal rotation. Therefore, phenolic resin has high brittleness and insufficient toughness. Therefore, it is necessary to synthesize a phenolic resin with a multi-functional structure to meet the increasingly stringent material usage requirements. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a flame-retardant phenolic resin molding material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A flame-retardant phenolic resin molding material comprises the following raw materials in parts by weight: 60 - 70 parts of modified phenolic resin, 10 - 15 parts of epoxy resin, 15 - 20 parts of inorganic filler, 30 - 35 parts of organic filler, 1.5 - 2.5 parts of release agent, 5 - 8 parts of curing agent, 3 - 4 parts of curing assistant, and 1 - 2 parts of colorant.

[0006] The epoxy resin is bisphenol A type epoxy resin.

[0007] The inorganic filler is glass fiber.

[0008] The organic filler is a composition with a mass ratio of wood powder to cellulose of 1:1.

[0009] The release agent is a composition with a mass ratio of magnesium stearate to zinc stearate of 3:7.

[0010] The curing agent is maleimide.

[0011] The curing aid is slaked lime.

[0012] The colorant is carbon black.

[0013] The modified phenolic resin is prepared by the following steps: Step A1: Add ginkgolic acid into acetic anhydride, add sulfuric acid solution, stir and react at 100 - 110 °C for 6 - 7 h, and then extract with dichloromethane to obtain Intermediate 1. The dosage ratio of ginkgolic acid, acetic anhydride and sulfuric acid solution is 0.1 mol: 0.05 mol - 0.08 mol: 10 - 12 mL, and the mass fraction of the sulfuric acid solution is 98%; During the reaction process, the phenolic hydroxyl group in ginkgolic acid undergoes an esterification reaction with acetic anhydride to protect the phenolic hydroxyl group, obtaining Intermediate 1. The structure of Intermediate 1 is shown as follows:

[0014] Step A2: Add Intermediate 1, 3 - aminopropyltrimethoxysilane and DMF into a flask equipped with a condensing reflux device, a stirring device and a thermometer. After refluxing and stirring at 45 °C for 4 h, cool to room temperature, filter, extract and dry to obtain Intermediate 2. The dosage ratio of Intermediate 1, 3 - aminopropyltrimethoxysilane and DMF is 0.1 mol: 0.15 - 0.18 mol: 120 - 150 mL; During the reaction process, the carboxyl group of Intermediate 1 and the amino group in 3 - aminopropyltrimethoxysilane undergo an amidation reaction to generate Intermediate 2. The structure of Intermediate 2 is shown as follows:

[0015] Step A3: Add Intermediate 2, glacial acetic acid and phosphoric acid into a round - bottom flask and stir to mix. Add hydrogen peroxide within 30 - 40 min, stir and react at 50 °C for 4 h, and then perform reduced - pressure distillation at 60 °C to obtain Intermediate 3. The dosage ratio of Intermediate 2, glacial acetic acid, phosphoric acid and hydrogen peroxide is 1 g: 0.15 g: 0.01 g: 0.8 g - 1 g; During the reaction process, the unsaturated alkenyl group in Intermediate 2 is oxidized to an epoxy group to obtain Intermediate 3. The structure of Intermediate 3 is shown as follows:

[0016] Step A4: Add intermediate 3 and DOPO into a four-necked flask equipped with a stirring device, a reflux condenser, and a thermometer. Heat it to 90°C. After 10 - 15 min, add triphenylphosphine. Then continue to raise the temperature to 150°C and maintain it for 3.5 - 4 h to obtain reaction solution a. After cooling reaction solution a to room temperature, add ethyl acetate to reaction solution a. Let it stand for 48 h and then filter to obtain intermediate 4. The dosage ratio of intermediate 3, DOPO, triphenylphosphine, and ethyl acetate is 0.1 mol : 0.1 - 0.15 mol : 0.005 - 0.008 mol : 80 - 90 mL; During the reaction process, the epoxy group in intermediate 3 reacts with DOPO to generate intermediate 4. The structure of intermediate 4 is shown as follows:

[0017] Step A5: Add phenolic resin, intermediate 4, and acetic acid into a flask equipped with a stirring device, a reflux condenser, and a thermometer. Slowly heat it to 90°C and maintain it for 20 - 24 h to obtain reaction solution b. After cooling reaction solution b to room temperature, distill reaction solution b under reduced pressure at 100°C for 40 - 60 min to obtain the modified phenolic resin. The dosage ratio of phenolic resin, intermediate 4, and acetic acid is 0.8 - 1 mol : 1 mol : 0.02 mol; During the reaction process, phenolic resin reacts with intermediate 4 to obtain the modified phenolic resin. The introduction of organosilicon and DOPO endows the phenolic resin with good flame retardancy. In ordinary phenolic resin, the presence of benzene rings makes it have greater rigidity, and the introduction of flexible long chains improves the flexibility of the resin. The phenolic hydroxyl groups in phenolic resin react with silanes, consuming the phenolic hydroxyl groups, which can reduce the water absorption rate of phenolic resin and enhance the aging resistance of the resin. The structure of the modified phenolic resin is shown as follows:

[0018] Advantages of the present invention: The raw materials of the flame-retardant phenolic resin molding material of the present invention include modified phenolic resin, epoxy resin, inorganic filler, organic filler, mold release agent, curing agent, curing aid, and colorant. The modified phenolic resin used is obtained by an etherification reaction between phenolic resin and silane, introducing organosilicon, DOPO structure, and long straight-chain alkane into the phenolic resin.

[0019] The silyl group can be grafted onto the resin through reaction to protect the phenolic hydroxyl group from oxidation. The silyl group can also self-polymerize into silicon-rich particles and then be oxidized into a silica structure, thereby exhibiting antioxidant properties. The introduction of silicon improves both the thermal stability and antioxidant properties of the phenolic resin, thus enhancing the flame retardancy and antioxidant properties of the molding material. The reaction of the phenolic hydroxyl group with the silane consumes the phenolic hydroxyl group, reducing the water absorption rate of the phenolic resin and enhancing the aging resistance of the resin, thereby improving the aging resistance of the molding material. The introduction of DOPO enables the resin to generate phosphorus-containing compounds during pyrolysis. The phosphorus-containing compounds can capture free radicals in the gas phase and inhibit combustion. The decomposition products in the condensed phase generated by the pyrolysis of the resin form a flame-retardant carbonized layer, and flame-retardant groups are introduced into the resin through reaction, avoiding the migration of additive small-molecule flame retardants and being more conducive to enhancing the flame retardancy of the molding material. In ordinary phenolic resins, the presence of the benzene ring increases the rigidity, resulting in increased brittleness of the molding material, while the introduction of flexible long straight-chain alkanes increases the flexibility of the resin, thus improving the toughness and processability of the molding material. Detailed implementation manners

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Embodiment

[0021] A modified phenolic resin is prepared through the following steps: Step A1: Add ginkgolic acid to acetic anhydride, add a sulfuric acid solution, stir and react at 100 °C for 6 h, and then extract with dichloromethane to obtain Intermediate 1. The dosage ratio of ginkgolic acid, acetic anhydride, and sulfuric acid solution is 0.1 mol: 0.05 mol: 10 mL, and the mass fraction of the sulfuric acid solution is 98%; Step A2: Add Intermediate 1, 3-aminopropyltrimethoxysilane, and DMF to a flask equipped with a condensation reflux device, a stirring device, and a thermometer. After refluxing and stirring at 45 °C for 4 h, cool to room temperature, filter, extract, and dry to obtain Intermediate 2. The dosage ratio of Intermediate 1, 3-aminopropyltrimethoxysilane, and DMF is 0.1 mol: 0.15 mol: 120 mL; Step A3: Add Intermediate 2, glacial acetic acid, and phosphoric acid to a round-bottom flask and stir and mix. Add hydrogen peroxide within 30 min, stir and react at 50 °C for 4 h, and then perform reduced-pressure distillation at 60 °C to obtain Intermediate 3. The dosage ratio of Intermediate 2, glacial acetic acid, phosphoric acid, and hydrogen peroxide is 1 g: 0.15 g: 0.01 g: 0.8 g; Step A4: Add intermediate 3 and DOPO into a four-necked flask equipped with a stirring device, a reflux condenser and a thermometer, heat to 90°C, add 0.8 g of triphenylphosphine after 10 min, continue to heat up to 150°C, and maintain for 3.5 h to obtain reaction solution a. Cool reaction solution a to room temperature, add ethyl acetate to reaction solution a, let it stand for 48 h, and then filter to obtain intermediate 4. The dosage ratio of intermediate 3, DOPO, triphenylphosphine and ethyl acetate is 0.1 mol: 0.1 mol: 0.005 mol: 80 mL; Step A5: Add phenolic resin, intermediate 4 and acetic acid into a flask equipped with a stirring device, a reflux condenser and a thermometer, slowly heat to 90°C, and maintain for 20 h to obtain reaction solution b. After cooling reaction solution b to room temperature, distill reaction solution b under reduced pressure at 100°C for 40 min to obtain the modified phenolic resin. The dosage ratio of phenolic resin, intermediate 4 and acetic acid is 0.8 mol: 1 mol: 0.02 mol. Example

[0022] A modified phenolic resin is prepared by the following steps: Step A1: Add ginkgolic acid into acetic anhydride, add sulfuric acid solution, stir and react at 105°C for 6.5 h, and then extract with dichloromethane to obtain intermediate 1. The dosage ratio of ginkgolic acid, acetic anhydride and sulfuric acid solution is 0.1 mol: 0.06 mol: 11 mL, and the mass fraction of the sulfuric acid solution is 98%; Step A2: Add intermediate 1, 3-aminopropyltrimethoxysilane and DMF into a flask equipped with a condensation reflux device, a stirring device and a thermometer. After refluxing and stirring at 45°C for 4 h, cool to room temperature, filter, extract and dry to obtain intermediate 2. The dosage ratio of intermediate 1, 3-aminopropyltrimethoxysilane and DMF is 0.1 mol: 0.16 mol: 135 mL; Step A3: Add intermediate 2, glacial acetic acid and phosphoric acid into a round-bottom flask and stir to mix. Add hydrogen peroxide within 35 min, stir and react at 50°C for 4 h, and then distill under reduced pressure at 60°C to obtain intermediate 3. The dosage ratio of intermediate 2, glacial acetic acid, phosphoric acid and hydrogen peroxide is 1 g: 0.15 g: 0.01 g: 0.9 g; Step A4: Add intermediate 3 and DOPO into a four-necked flask equipped with a stirring device, a reflux condenser and a thermometer, heat to 90°C, add 0.8 g of triphenylphosphine after 12 min, continue to heat up to 150°C, and maintain for 3.7 h to obtain reaction solution a. Cool reaction solution a to room temperature, add ethyl acetate to reaction solution a, let it stand for 48 h, and then filter to obtain intermediate 4. The dosage ratio of intermediate 3, DOPO, triphenylphosphine and ethyl acetate is 0.1 mol: 0.12 mol: 0.006 mol: 85 mL; Step A5: Add phenolic resin, intermediate 4, and acetic acid into a flask equipped with a stirring device, a reflux condenser, and a thermometer. Slowly heat it to 90 °C and maintain for 22 h to obtain reaction solution b. After cooling reaction solution b to room temperature, subject reaction solution b to vacuum distillation at 100 °C for 50 min to obtain the modified phenolic resin. The dosage ratio of phenolic resin, intermediate 4, and acetic acid is 0.9 mol: 1 mol: 0.02 mol. Example

[0023] A modified phenolic resin is prepared through the following steps: Step A1: Add ginkgolic acid into acetic anhydride, add sulfuric acid solution, and stir and react at 110 °C for 7 h. Then extract with dichloromethane to obtain intermediate 1. The dosage ratio of ginkgolic acid, acetic anhydride, and sulfuric acid solution is 0.1 mol: 0.08 mol: 12 mL, and the mass fraction of the sulfuric acid solution is 98%; Step A2: Add intermediate 1, 3-aminopropyltrimethoxysilane, and DMF into a flask equipped with a reflux condensation device, a stirring device, and a thermometer. After refluxing and stirring at 45 °C for 4 h, cool to room temperature, filter, extract, and dry to obtain intermediate 2. The dosage ratio of intermediate 1, 3-aminopropyltrimethoxysilane, and DMF is 0.1 mol: 0.18 mol: 150 mL; Step A3: Add intermediate 2, glacial acetic acid, and phosphoric acid into a round-bottom flask and stir and mix. Add hydrogen peroxide within 40 min, stir and react at 50 °C for 4 h, and then subject to vacuum distillation at 60 °C to obtain intermediate 3. The dosage ratio of intermediate 2, glacial acetic acid, phosphoric acid, and hydrogen peroxide is 1 g: 0.15 g: 0.01 g: 1 g; Step A4: Add intermediate 3 and DOPO into a four-necked flask equipped with a stirring device, a reflux condenser, and a thermometer. Heat to 90 °C, add 0.8 g of triphenylphosphine after 15 min, continue to heat up to 150 °C, and maintain for 4 h to obtain reaction solution a. After cooling reaction solution a to room temperature, add ethyl acetate to reaction solution a, let it stand for 48 h, and then filter to obtain intermediate 4. The dosage ratio of intermediate 3, DOPO, triphenylphosphine, and ethyl acetate is 0.1 mol: 0.15 mol: 0.008 mol: 90 mL; Step A5: Add phenolic resin, intermediate 4, and acetic acid into a flask equipped with a stirring device, a reflux condenser, and a thermometer. Slowly heat it to 90 °C and maintain for 24 h to obtain reaction solution b. After cooling reaction solution b to room temperature, subject reaction solution b to vacuum distillation at 100 °C for 60 min to obtain the modified phenolic resin. The dosage ratio of phenolic resin, intermediate 4, and acetic acid is 1 mol: 1 mol: 0.02 mol. Example

[0024] A flame-retardant phenolic resin molding material comprises the following raw materials in parts by weight: 60 parts of modified phenolic resin, 10 parts of epoxy resin, 15 parts of inorganic filler, 40 parts of organic filler, 1.5 parts of mold release agent, 5 parts of curing agent, 3 parts of curing aid, and 1 part of colorant. The epoxy resin is bisphenol A epoxy resin; the inorganic filler is glass fiber; the organic filler is a composition of wood powder and cellulose with a mass ratio of 1:1; the mold release agent is a composition of magnesium stearate and zinc stearate with a mass ratio of 3:7; the curing agent is maleimide; the curing aid is slaked lime; the colorant is carbon black.

[0025] The flame-retardant phenolic resin molding material is prepared through the following steps: Add the modified phenolic resin, epoxy resin, inorganic filler, organic filler, mold release agent, curing agent, curing aid, and colorant obtained in Example 1 into a reaction kettle, stir for 30 min, then take out after melt-kneading with a heating roll at 90 °C for 3 min, and crush into granular form to obtain the flame-retardant phenolic resin molding material. Example

[0026] A flame-retardant phenolic resin molding material comprises the following raw materials in parts by weight: 65 parts of modified phenolic resin, 12 parts of epoxy resin, 17 parts of inorganic filler, 42 parts of organic filler, 2 parts of mold release agent, 6 parts of curing agent, 3.5 parts of curing aid, and 1.5 parts of colorant. The epoxy resin is bisphenol A epoxy resin; the inorganic filler is glass fiber; the organic filler is a composition of wood powder and cellulose with a mass ratio of 1:1; the mold release agent is a composition of magnesium stearate and zinc stearate with a mass ratio of 3:7; the curing agent is maleimide; the curing aid is slaked lime; the colorant is carbon black.

[0027] The flame-retardant phenolic resin molding material is prepared through the following steps: Add the modified phenolic resin, epoxy resin, inorganic filler, organic filler, mold release agent, curing agent, curing aid, and colorant obtained in Example 2 into a reaction kettle, stir for 40 min, then take out after melt-kneading with a heating roll at 90 °C for 4 min, and crush into granular form to obtain the flame-retardant phenolic resin molding material. Example

[0028] A flame-retardant phenolic resin molding material comprises the following raw materials in parts by weight: 70 parts of modified phenolic resin, 15 parts of epoxy resin, 20 parts of inorganic filler, 45 parts of organic filler, 2.5 parts of mold release agent, 8 parts of curing agent, 4 parts of curing aid, and 2 parts of colorant. The epoxy resin is bisphenol A epoxy resin; the inorganic filler is glass fiber; the organic filler is a composition of wood powder and cellulose with a mass ratio of 1:1; the mold release agent is a composition of magnesium stearate and zinc stearate with a mass ratio of 3:7; the curing agent is maleimide; the curing aid is slaked lime; the colorant is carbon black.

[0029] The flame-retardant phenolic resin molding material is prepared through the following steps: Add the modified phenolic resin, epoxy resin, inorganic filler, organic filler, mold release agent, curing agent, curing aid and colorant obtained in Example 3 into a reaction kettle, stir for 45 min, then take it out after melt-kneading with a heating roll at 90 °C for 5 min, and crush it into granular form to obtain the flame-retardant phenolic resin molding material.

[0030] Comparative Example 1 This comparative example is a commercially available flame-retardant phenolic resin molding material.

[0031] Comparative Example 2 Compared with Example 6, replace the modified phenolic resin with ordinary phenolic resin, and the others are exactly the same as Example 6 to prepare the flame-retardant phenolic resin molding material.

[0032] The following is a further effect test on the flame-retardant phenolic resin molding material prepared by the present invention, and the test results are as follows.

[0033] To test the flame-retardant phenolic resin molding material prepared by the present invention, the properties are measured according to GB / T9341-2008 "Plastics - Determination of flexural properties" and GB / T1034-2008 "Plastics - Determination of water absorption", etc., and the results are shown in Table 1.

[0034] Table 1:

[0035] According to the data in Table 1, it can be seen from the comparison of Example 4, Example 5 and Example 6 with Comparative Example 1 that compared with the commercially available flame-retardant phenolic resin molding material, the flame-retardant phenolic resin molding material prepared by the present invention has a lower water absorption rate, excellent toughness and flame-retardant performance; it can be seen from the comparison of Example 6 with Comparative Example 2 that compared with the flame-retardant phenolic resin molding material prepared by using only ordinary phenolic resin instead of the modified phenolic resin molding material, the water absorption rate of the molding material increases, which is not conducive to the aging resistance of the molding material; the weight change rate of the molding material when placed in an oven at 300 °C for 4 h increases, indicating that the heat resistance of the molding material decreases and the flame-retardant performance decreases; the flexural strength of the molding material decreases, indicating that the toughness of the molding material decreases.

[0036] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of the present technology make various modifications or supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the concept of the invention or exceed the scope defined by this claims, they should all belong to the protection scope of the present invention.

Claims

1. A flame retardant phenolic resin molding material, characterized in that: The invention comprises the following raw materials in parts by weight: 60-70 parts of modified phenolic resin, 10-15 parts of epoxy resin, 15-20 parts of inorganic filler, 30-35 parts of organic filler, 1.5-2.5 parts of release agent, 5-8 parts of curing agent, 3-4 parts of curing aid and 1-2 parts of colorant; The modified phenolic resin is prepared by the following steps: Step A1: Add ginkgolic acid to acetic anhydride, add sulfuric acid solution, react at 100-110°C for 6-7h, and then extract with dichloromethane to obtain intermediate 1; Step A2: Add intermediate 1, 3-aminopropyltrimethoxysilane and DMF into a flask equipped with a condensing reflux device, a stirring device and a thermometer, reflux and stir at 45° C. for 4 hours, cool to room temperature, filter, extract and dry to obtain intermediate 2; Step A3: Add intermediate 2, glacial acetic acid and phosphoric acid into a round-bottom flask and stir to mix, add hydrogen peroxide within 30-40 min, stir and react at 50° C. for 4 h, and then distill under reduced pressure at 60° C. to obtain intermediate 3; Step A4: Add intermediate 3 and DOPO into a four-necked flask equipped with a stirring device, a reflux condenser and a thermometer, heat to 90°C, add triphenylphosphine after 10-15 minutes, continue to heat to 150°C, maintain for 3.5-4 hours, obtain reaction solution a, cool reaction solution a to room temperature, add ethyl acetate to reaction solution a, let stand for 48 hours, and filter to obtain intermediate 4; Step A5: Add phenolic resin, intermediate 4 and acetic acid into a flask equipped with a stirring device, a reflux condenser and a thermometer, slowly heat to 90°C, and maintain for 20-24 hours to obtain reaction solution b. After the reaction solution b is cooled to room temperature, the reaction solution b is distilled under reduced pressure at 100°C for 40-60 minutes to obtain a modified phenolic resin.

2. The flame retardant phenolic resin molding material according to claim 1, characterized in that: The epoxy resin is bisphenol A epoxy resin, the inorganic filler is glass fiber, the organic filler is a composition of wood powder and cellulose in a mass ratio of 1:1, the release agent is a composition of magnesium stearate and zinc stearate in a mass ratio of 3:7, the curing agent is maleimide, the curing aid is slaked lime, and the colorant is carbon black.

3. The flame retardant phenolic resin molding material according to claim 1, characterized in that: In step A1, the usage ratio of ginkgo acid, acetic anhydride and sulfuric acid solution is 0.1 mol: 0.05 mol-0.08 mol: 10-12 mL, and the mass fraction of sulfuric acid solution is 98%.

4. The flame retardant phenolic resin molding material according to claim 1, characterized in that: In step A2, the usage ratio of intermediate 1, 3-aminopropyltrimethoxysilane and DMF is 0.1 mol: 0.15-0.18 mol: 120-150 mL.

5. The flame retardant phenolic resin molding material according to claim 1, characterized in that: In step A3, the usage ratio of intermediate 2, glacial acetic acid, phosphoric acid and hydrogen peroxide is 1g:0.15g:0.01g:0.8g-1g.

6. The flame retardant phenolic resin molding material according to claim 1, characterized in that: In step A4, the usage ratio of intermediate 3, DOPO, triphenylphosphine and ethyl acetate is 0.1 mol: 0.1-0.15 mol: 0.005-0.008 mol: 80-90 mL.

7. The flame retardant phenolic resin molding material according to claim 1, characterized in that: In step A5, the usage ratio of phenolic resin, intermediate 4 and acetic acid is 0.8-1 mol: 1 mol: 0.02 mol.

8. The method for preparing a flame retardant phenolic resin molding material according to claim 1, characterized in that: Prepared by the following steps: Add modified phenolic resin, epoxy resin, inorganic filler, organic filler, release agent, curing agent, curing aid and colorant into a reaction kettle, stir for 30-45 minutes, then use a 90°C heating roller to melt-mix for 3-5 minutes, take out, and crush into particles to obtain a flame-retardant phenolic resin molding material.

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