Thermal-insulation flame-retardant melamino-formaldehyde material and preparation method thereof

Abstract

The invention relates to a thermal-insulation flame-retardant melamine formaldehyde material and a preparation method thereof, and belongs to the technical field of preparation of melamine formaldehyde materials. The melamino-formaldehyde material prepared by the preparation method disclosed by the invention has relatively high heat-insulating and flame-retardant effects and relatively good mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of melamine formaldehyde material preparation, and relates to a heat-insulating and flame-retardant melamine formaldehyde material and a preparation method thereof. Background Art

[0002] Melamine rigid foam is a new type of rigid foam plastic made from modified melamine formaldehyde resin, mixed with surfactants, blowing agents, curing agents, and leveling agents, and then heated and foamed in an oven or microwave. Melamine rigid foam is a closed-cell material with a closed-cell ratio exceeding 90%. It effectively blocks heat transfer and moisture infiltration, while also exhibiting excellent flame retardancy and high-temperature resistance, and generating relatively low smoke. It is well-suited for use as a thermal insulation and fireproofing material in construction, industrial equipment, transportation, and the new energy sector.

[0003] Traditional melamine-formaldehyde resin is a high-molecular-weight polymer formed by the advanced addition reaction of melamine and formaldehyde followed by polycondensation. Due to the high rigidity of the triazine ring, short intermolecular crosslinks, and high crosslink density, melamine rigid foam is relatively brittle and has poor impact resistance, making it unsuitable for product use. To increase the toughness of melamine rigid foam, the melamine-formaldehyde resin needs to be modified to impart suitable mechanical properties, enabling its application in various fields. Summary of the Invention

[0004] The main purpose of the present invention is to provide a melamine formaldehyde material, which has high heat insulation and flame retardant effects and good mechanical properties.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0006] A method for preparing a heat-insulating flame-retardant melamine-formaldehyde material mainly comprises the following steps:

[0007] Step A, 100 parts by weight of modified tung oil, 60 parts by weight of phenol, and 1 part by weight of tetrafluoroboric acid were mixed, stirred at 90° C. for 1 hour, and then cooled to 70° C. to obtain Product 1;

[0008] Step B, adding 50 parts by weight of paraformaldehyde and 30 parts by weight of melamine to product 1, adjusting the pH to 8.0-9.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 parts by weight of melamine, adjusting the pH to 5.5-6.0, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0-7.5, and discharging the mixture to obtain melamine formaldehyde resin;

[0009] Step C: 100 parts by weight of the melamine formaldehyde resin obtained in step B, 5-10 parts by weight of aluminum diethylphosphinate, 9-10 parts by weight of a foaming agent, and 7-9 parts by weight of a surfactant are stirred and mixed for 1 minute, 25-30 parts by weight of a curing agent are added, and stirring is continued. The mixture is then poured into a preheated mold, placed in an 80° C. oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0010] Preferably, the preparation method of the modified tung oil in step A comprises the following steps:

[0011] Step 1: Add 100 parts by weight of tung oil, 10 parts by weight of n-dodecyl mercaptan, 30 parts by weight of methanol, and 1.5 parts by weight of KOH into a flask, stir in a water bath at 60° C. for 3.5-4 hours, then add formic acid to adjust to neutrality, wash with hot water three times, and remove residual water by vacuum rotary evaporation to obtain a primary product;

[0012] Step 2: placing the primary product in a flask, adding 40 parts by weight of triethylamine, starting magnetic stirring, and slowly adding 50 parts by weight of diethyl chlorophosphate to the mixture under ice-water bath conditions; after the addition of diethyl chlorophosphate is completed, heating in a water bath at 25° C. for 3 hours, then washing with purified water until neutral, and removing residual water by vacuum rotary evaporation to obtain modified tung oil.

[0013] Preferably, the foaming agent in step C is n-pentane, a mixture of n-pentane and isopentane, or n-hexane.

[0014] Further preferably, when the foaming agent in step C is a mixture of n-pentane and isopentane, the weight ratio of n-pentane to isopentane is 4:1.

[0015] Preferably, the surfactant in step C is Tween-80.

[0016] Preferably, the curing agent in step C is an organic acid curing agent.

[0017] More preferably, the organic acid curing agent is mainly formic acid or acetic acid.

[0018] The present invention provides a melamine formaldehyde material prepared by the above preparation method.

[0019] The present invention has the following beneficial effects:

[0020] 1. The melamine formaldehyde foam material prepared in the present invention has high flame retardancy and mechanical properties while ensuring high thermal insulation effect, and has a wide range of applications.

[0021] 2. In the preparation process of the melamine formaldehyde foam material of the present invention, tung oil is added to improve the foam material and enhance its toughness. However, the addition of tung oil will reduce the thermal stability. Therefore, the flame retardant diethyl aluminum hypophosphite is added. However, the addition of the flame retardant affects the resin, resulting in a decrease in mechanical properties, and the flame retardant effect of a single flame retardant is not ideal. Therefore, the tung oil is modified in the present invention so that the modified tung oil can improve the thermal stability while improving the toughness of the foam material. In addition, the modified tung oil is conducive to the distribution of diethyl aluminum hypophosphite in the resin, thereby improving the mechanical properties. DETAILED DESCRIPTION

[0022] The present invention is further illustrated below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention made by those skilled in the art all fall within the scope of protection of the claims of this application.

[0023] Example 1

[0024] First, prepare modified tung oil

[0025] Step 1: Add 100 g of tung oil, 10 g of n-dodecyl mercaptan, 30 g of methanol, and 1.5 g of KOH to a flask, stir in a 60° C. water bath for 3.5-4 h, then add formic acid to adjust to neutrality, wash with hot water three times, and remove residual water by vacuum rotary evaporation to obtain a primary product;

[0026] Step 2: placing the initial product in a flask, adding 40 g of triethylamine, starting magnetic stirring, and slowly adding 50 g of diethyl chlorophosphate to the above mixture under ice-water bath conditions, and controlling the addition of diethyl chlorophosphate within 1 hour; after the addition of diethyl chlorophosphate is completed, heating to 25° C. in a water bath for 3 hours, then washing with purified water until neutral, and removing residual water by vacuum rotary evaporation to obtain modified tung oil.

[0027] Then, prepare melamine formaldehyde foam material

[0028] Step A: 100 g of the modified tung oil prepared above, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90° C. for 1 h, and then cooled to 70° C. to obtain product 1;

[0029] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 8.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0, and discharging the mixture to obtain melamine formaldehyde resin;

[0030] Step C: 100 g of the melamine formaldehyde resin obtained above, 5 g of aluminum diethylphosphinate, 10 g of n-pentane, and 7 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 30 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0031] Example 2

[0032] First, prepare modified tung oil

[0033] Step 1: Add 100 g of tung oil, 10 g of n-dodecyl mercaptan, 30 g of methanol, and 1.5 g of KOH to a flask, stir in a 60° C. water bath for 3.5-4 h, then add formic acid to adjust to neutrality, wash with hot water three times, and remove residual water by vacuum rotary evaporation to obtain a primary product;

[0034] Step 2: placing the initial product in a flask, adding 40 g of triethylamine, starting magnetic stirring, and slowly adding 50 g of diethyl chlorophosphate to the above mixture under ice-water bath conditions, and controlling the addition of diethyl chlorophosphate within 1 hour; after the addition of diethyl chlorophosphate is completed, heating to 25° C. in a water bath for 3 hours, then washing with purified water until neutral, and removing residual water by vacuum rotary evaporation to obtain modified tung oil.

[0035] Then, prepare melamine formaldehyde foam material

[0036] Step A: 100 g of the modified tung oil prepared above, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90° C. for 1 h, and then cooled to 70° C. to obtain product 1;

[0037] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 9.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 6.0, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.5, and discharging the mixture to obtain melamine formaldehyde resin;

[0038] Step C: 100 g of the melamine formaldehyde resin obtained above, 10 g of aluminum diethylphosphinate, 9 g of n-hexane, and 9 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 25 g of acetic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0039] Example 3

[0040] First, prepare modified tung oil

[0041] Step 1: Add 100 g of tung oil, 10 g of n-dodecyl mercaptan, 30 g of methanol, and 1.5 g of KOH to a flask, stir in a 60° C. water bath for 3.5-4 h, then add formic acid to adjust to neutrality, wash with hot water three times, and remove residual water by vacuum rotary evaporation to obtain a primary product;

[0042] Step 2: placing the initial product in a flask, adding 40 g of triethylamine, starting magnetic stirring, and slowly adding 50 g of diethyl chlorophosphate to the above mixture under ice-water bath conditions, and controlling the addition of diethyl chlorophosphate within 1 hour; after the addition of diethyl chlorophosphate is completed, heating to 25° C. in a water bath for 3 hours, then washing with purified water until neutral, and removing residual water by vacuum rotary evaporation to obtain modified tung oil.

[0043] Then, prepare melamine formaldehyde foam material

[0044] Step A: 100 g of the modified tung oil prepared above, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90° C. for 1 h, and then cooled to 70° C. to obtain product 1;

[0045] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 9.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.5, and discharging the mixture to obtain melamine formaldehyde resin;

[0046] Step C: 100 g of the melamine formaldehyde resin obtained above, 8 g of aluminum diethylphosphinate, 8 g of n-pentane, 2 g of isopentane, and 8 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 28 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0047] Comparative Example 1

[0048] First, prepare modified tung oil

[0049] Add 100 g of tung oil, 10 g of n-dodecyl mercaptan, 30 g of methanol, and 1.5 g of KOH to a flask, stir in a 60°C water bath for 3.5-4 h, then evaporate the excess methanol. After standing and stratification, remove the upper liquid, adjust the mixture to neutral with formic acid, wash with hot water three times, and remove the residual water by vacuum rotary evaporation to obtain modified tung oil;

[0050] Then, prepare melamine formaldehyde foam material

[0051] Step A: 100 g of the modified tung oil prepared above, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90° C. for 1 h, and then cooled to 70° C. to obtain product 1;

[0052] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 8.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0, and discharging the mixture to obtain melamine formaldehyde resin;

[0053] Step C: 100 g of the melamine formaldehyde resin obtained above, 5 g of aluminum diethylphosphinate, 10 g of n-pentane, and 7 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 30 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0054] Comparative Example 2

[0055] First, prepare modified tung oil

[0056] Step 1: 100 g of tung oil and 40 g of triethylamine are placed in a flask, magnetic stirring is started, and 50 g of diethyl chlorophosphate is slowly added to the mixture under ice-water bath conditions, and the addition of diethyl chlorophosphate is controlled within 1 hour; after the addition of diethyl chlorophosphate is completed, the temperature is raised to 25° C. and heated in a water bath for 3 hours, and then washed with purified water until neutral, and residual water is removed by vacuum rotary evaporation to obtain modified tung oil.

[0057] Then, prepare melamine formaldehyde foam material

[0058] Step A: 100 g of the modified tung oil prepared above, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90° C. for 1 h, and then cooled to 70° C. to obtain product 1;

[0059] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 8.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0, and discharging the mixture to obtain melamine formaldehyde resin;

[0060] Step C: 100 g of the melamine formaldehyde resin obtained above, 5 g of aluminum diethylphosphinate, 10 g of n-pentane, and 7 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 30 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0061] Comparative Example 3

[0062] Step A: 100 g of tung oil, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90°C for 1 h, and then cooled to 70°C to obtain product 1;

[0063] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 8.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0, and discharging the mixture to obtain melamine formaldehyde resin;

[0064] Step C: 100 g of the melamine formaldehyde resin obtained above, 5 g of aluminum diethylphosphinate, 10 g of n-pentane, and 7 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 30 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0065] Comparative Example 4

[0066] Step A: 100 g of tung oil, 60 g of phenol, and 1 g of tetrafluoroboric acid were added to a flask, stirred at 90°C for 1 h, and then cooled to 70°C to obtain product 1;

[0067] Step B: adding 50 g of paraformaldehyde and 30 g of melamine to product 1, adjusting the pH to 8.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 g of melamine, adjusting the pH to 5.5, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0, and discharging the mixture to obtain melamine formaldehyde resin;

[0068] Step C: 100 g of the melamine formaldehyde resin obtained above, 10 g of n-pentane, and 7 g of Tween-80 were mixed under rapid stirring at 2000 r / min for 1 minute, 30 g of formic acid was added, and rapid stirring at 2000 r / min was continued. The mixture was then poured into a preheated mold, placed in an 80°C oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

[0069] Mechanical properties testing

[0070] The foam materials obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to mechanical property tests (impact test, tensile test, bending test), and the average of three test results was taken for each test. The results are shown in Table 1. The free formaldehyde content in the different foam materials was also measured.

[0071] From the results in Table 1, it can be seen that the free formaldehyde content in the foam materials prepared in Examples 1-3 and Comparative Examples 1-2 all meet the national standards (<0.2%), while the free formaldehyde content in the foam materials prepared in Comparative Examples 3-4 is 0.22%, which does not meet the national standards.

[0072] The foam materials prepared in Examples 1-3 of the present invention have good mechanical properties, and their compressive strength and flexural strength are significantly higher than those of the foam materials prepared in Comparative Examples 1-4. The reason is that the tung oil added in Comparative Example 4 improves the mechanical properties of the foam material. In Comparative Example 3, the flame retardant diethyl aluminum hypophosphite is added on the basis of the addition of tung oil, resulting in a decrease in the mechanical properties. However, the use of diethyl aluminum hypophosphite in Comparative Examples 1-2 will affect the mechanical properties of the foam material. After the modified tung oil (different from the present invention) is added, the mechanical properties are improved, but the effect is still not ideal.

[0073] Table 1 Mechanical properties of different rigid foams

[0074] Foam material Free aldehyde (%) Compressive strength (MPa) Flexural strength (MPa) Example 1 0.11 0.31 0.41 Example 2 0.09 0.29 0.43 Example 3 0.13 0.32 0.44 Comparative Example 1 0.16 0.25 0.34 Comparative Example 2 0.15 0.22 0.32 Comparative Example 3 0.22 0.19 0.31 Comparative Example 4 0.21 0.27 0.38

[0075] Flame retardant properties and thermogravimetric analysis tests

[0076] The limiting oxygen index (LOI) was determined according to GB / T2046.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test" and the limiting oxygen index analysis of the foam materials obtained in Examples 1-3 and Comparative Examples 1-4 was performed.

[0077] The foam material samples obtained in Examples 1-3 and Comparative Examples 1-4 were placed in a muffle furnace and burned, and their carbon residue rates were recorded.

[0078] The foam materials obtained in Examples 1-3 and Comparative Examples 1-4 were tested using a thermal analysis instrument. The samples were heated from 40° C. to 800° C. at a heating rate of 10° C. / min in an air atmosphere.

[0079] From the results in Table 2 and Table 3, it can be seen that the foam materials prepared in Examples 1-3 of the present invention have higher thermal stability and better flame retardant properties.

[0080] The presence of tung oil in the foam material prepared in Comparative Example 4 reduces the thermal stability of the foam material. In Comparative Example 3, a flame retardant, diethyl aluminum hypophosphite, is added to the tung oil, and its stability is improved, but the effect is not ideal. In Comparative Examples 1-2, after the tung oil is modified (different from the present invention), the stability of the foam material is improved, but it is still not as good as the foam materials prepared in Examples 1-3 of the present invention.

[0081] Table 2 Carbon residue rate and limiting oxygen index of different rigid foams

[0082]

[0083]

[0084] Table 2 Thermogravimetric analysis results of different rigid foams

[0085] Foam material <![CDATA[T 2wt％ / ℃]]> <![CDATA[T 5wt％ / ℃]]> <![CDATA[T 10wt％ / ℃]]> <![CDATA[T max / ℃]]> Residual rate at 800℃ / % Example 1 183 257 303 364 24.01 Example 2 197 263 315 351 23.6 Example 3 202 272 311 359 24.8 Comparative Example 1 151 196 252 327 20.4 Comparative Example 2 162 214 267 339 22.9 Comparative Example 3 138 173 238 312 18.1 Comparative Example 4 116 151 216 298 16.2

[0086] Performance Test 3

[0087] The thermal conductivity of the foam materials obtained in Examples 1-3 and Comparative Examples 1-4 was analyzed. The results are shown in Table 3.

[0088] As can be seen from the results in Table 3, the thermal conductivity of the foam materials prepared in Examples 1-3 of the present invention is significantly lower, indicating that their thermal insulation effect is better.

[0089] Table 3 Thermal conductivity of different rigid foams

[0090]

[0091]

Claims

1. A method for preparing a heat-insulating flame-retardant melamine-formaldehyde material, characterized in that: The preparation method comprises the following steps: Step A, 100 parts by weight of modified tung oil, 60 parts by weight of phenol, and 1 part by weight of tetrafluoroboric acid were mixed, stirred at 90° C. for 1 hour, and then cooled to 70° C. to obtain Product 1; Step B, adding 50 parts by weight of paraformaldehyde and 30 parts by weight of melamine to product 1, adjusting the pH to 8.0-9.0 with a 30% by mass aqueous NaOH solution, keeping the mixture at 80° C. for 2 hours, then heating it to 90° C. and keeping it for 1 hour; cooling it to 50° C., adding 50 parts by weight of melamine, adjusting the pH to 5.5-6.0, heating it to 70° C. and keeping it for 1 hour, then cooling it to 40° C., adjusting the pH to 7.0-7.5, and discharging the mixture to obtain melamine formaldehyde resin; Step C: 100 parts by weight of the melamine formaldehyde resin obtained in step B, 5-10 parts by weight of aluminum diethylphosphinate, 9-10 parts by weight of a foaming agent, and 7-9 parts by weight of a surfactant are stirred and mixed for 1 minute, 25-30 parts by weight of a curing agent are added, and stirring is continued. The mixture is then poured into a preheated mold, placed in an 80° C. oven for curing for 1 hour, and demolded to obtain a melamine formaldehyde foam material.

2. The preparation method according to claim 1, characterized in that The preparation method of the modified tung oil in step A comprises the following steps: Step 1: Add 100 parts by weight of tung oil, 10 parts by weight of n-dodecyl mercaptan, 30 parts by weight of methanol, and 1.5 parts by weight of KOH into a flask, stir in a 60° C. water bath for 3.5-4 hours, then add formic acid to adjust to neutrality, wash with hot water three times, and remove residual water by vacuum rotary evaporation to obtain a primary product; Step 2: placing the primary product in a flask, adding 40 parts by weight of triethylamine, starting magnetic stirring, and slowly adding 50 parts by weight of diethyl chlorophosphate to the mixture under ice-water bath conditions; after the addition of diethyl chlorophosphate is completed, heating in a water bath at 25° C. for 3 hours, then washing with purified water until neutral, and removing residual water by vacuum rotary evaporation to obtain modified tung oil.

3. The preparation method according to claim 1, characterized in that The foaming agent in step C is n-pentane, a mixture of n-pentane and isopentane, or n-hexane.

4. The preparation method according to claim 3, characterized in that The weight ratio of n-pentane to isopentane is 4:

1.

5. The preparation method according to claim 1, characterized in that The surfactant in step C is Tween-80.

6. The preparation method according to claim 1, characterized in that The curing agent in step C is an organic acid curing agent.

7. The preparation method according to claim 6, characterized in that The organic acid curing agent is formic acid or acetic acid.

8. A melamine formaldehyde material prepared by the preparation method according to any one of claims 1 to 7.

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