Pressure-resistant thermal expansion microcapsule and preparation method thereof

Abstract

The invention relates to the technical field of thermal expansion microcapsules, in particular to a pressure-resistant thermal expansion microcapsule and a preparation method thereof.The preparation method comprises the following steps that 1, a dispersion medium, inorganic salt, a dispersion stabilizer and a dispersion stabilizing additive are mixed, and a water phase is obtained; 2) mixing a monomer, an initiator, a cross-linking agent and a foaming agent to obtain an oil phase; 3) uniformly stirring the oil phase and the water phase to obtain a suspension; and 4) carrying out polymerization reaction on the obtained suspension in an inert atmosphere at 40-80 DEG C under the pressure of 0.01-1 MPa for 10-25 hours, filtering and drying to obtain the pressure-resistant thermal expansion microcapsule.

Description

Technical Field

[0001] The invention relates to the technical field of thermal expansion microcapsules, and in particular to a pressure-resistant thermal expansion microcapsule and a preparation method thereof. Background Art

[0002] Emulsion explosives have become the most widely used type of industrial explosives in my country due to their excellent explosive performance and water resistance. Sensitization is an important link and technical difficulty in the production of emulsion explosives. The theoretical basis of emulsion explosive sensitization is the hot spot theory. Chemical foaming sensitization or physical sensitization can adjust the density of emulsion explosives and improve their detonation sensitivity. Chemical sensitization has the characteristics of low cost, small dosage, and good sensitization effect. However, chemical sensitization has the disadvantages of many influencing factors, complex operation, easy aggregation and escape of sensitized bubbles, relatively low storage stability, and serious pressure desensitization phenomenon. At present, the high-temperature rapid chemical foaming technology of emulsion explosives in my country has poor solid foaming performance, and the controllability of chemical foaming is not strong. Physical sensitization generally adds hollow glass microspheres or expanded perlite particles to the latex matrix, and uses the adiabatic compression of the gas in its cavity to form a "hot spot" to achieve sensitization. Considering the cost, expanded perlite is often used as a sensitizer in China. The cost is relatively low, but it has the following disadvantages: (1) The surface of perlite powder is rough and angular, with poor compression resistance and easy to break; (2) Expanded perlite is highly lipophilic, with large and open pores. During the production and storage of emulsion explosives, a certain amount of high-temperature latex matrix will be absorbed into the body, blocking the pores; (3) As a sensitizer for emulsion explosives, perlite is used in large quantities, accounting for about 3% to 5% of the total mass, resulting in a decrease in the quality and power of the emulsion explosives.

[0003] Therefore, the development direction of emulsion explosive sensitization technology is high-temperature sensitization. The pressure-resistant heat-expandable microcapsules in the present invention are used as sensitizers. They have good elasticity and can withstand greater pressure. After heating, the volume can expand rapidly to several dozen times of its own without breaking. For emulsion explosives, they have excellent sensitization performance and are used in small amounts. The usage amount is only 0.4%, which can be used as a good high-temperature sensitizer for emulsion explosives. Summary of the invention

[0004] The object of the present invention is to provide a pressure-resistant heat-expandable microcapsule and a preparation method thereof, so as to overcome the defects of the prior art.

[0005] In order to solve the above technical problems, the present invention provides a pressure-resistant heat-expandable microcapsule, which is characterized by comprising the following steps:

[0006] (1) mixing a dispersion medium, an inorganic salt, a dispersion stabilizer, and a dispersion stabilization aid to obtain an aqueous phase;

[0007] (2) mixing monomers, initiators, crosslinking agents and foaming agents to obtain an oil phase;

[0008] (3) stirring the oil phase and the water phase to obtain a suspension;

[0009] (4) The obtained suspension is subjected to polymerization reaction for 10 to 25 hours under an inert atmosphere (including one or more of nitrogen or argon) at 40 to 80° C. and a pressure of 0.01 to 1 MPa, and then filtered and dried to obtain pressure-resistant heat-expandable microcapsules.

[0010] Furthermore, in step (1), the inorganic salt is one or more of sodium chloride, sodium nitrate, sodium nitrite, potassium chloride, magnesium chloride, calcium chloride, calcium nitrate, and magnesium nitrate, preferably sodium nitrite;

[0011] Furthermore, in step (1), the dispersion stabilizer is one or more of salts of metal magnesium, manganese, calcium, sodium and zinc, metal oxides and metal hydroxides, preferably sodium hydroxide;

[0012] Furthermore, in step (1), the dispersion stabilization aid is one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene oxide, calcium phosphate, and barium sulfate, preferably polyvinyl alcohol;

[0013] Furthermore, in step (2), the monomer is one or more of acrylonitrile monomers, ethylene monomers, acrylate monomers, acrylamide monomers, and fluorine-containing acrylate monomers;

[0014] Furthermore, in step (2), the acrylonitrile monomer is one or more of acrylonitrile and methacrylonitrile, preferably acrylonitrile; the ethylene monomer is one or more of vinylidene chloride and trifluoroethylene, preferably trifluoroethylene; the acrylate monomer is one or two of methyl methacrylate, ethyl methacrylate, and butyl methacrylate, preferably one or two of methyl methacrylate and ethyl methacrylate; the acrylamide monomer is one or more of acrylamide, methacrylamide, N-ethylacrylamide, and N,N-dimethylacrylamide, preferably methacrylamide; and the fluorine-containing acrylate monomer is methyl 2-fluoroacrylate.

[0015] Furthermore, the monomer in step (2) comprises the following components in parts by weight:

[0016]

[0017] Furthermore, in step (2), the initiator is one or more of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), diisopropyl peroxydicarbonate, di-sec-butyl peroxide, di(2-ethylhexyl) peroxydicarbonate, lauroyl peroxide, benzoyl peroxide and other diacyl peroxides, and di-tert-butyl peroxide, preferably 2,2'-azobisisobutyronitrile.

[0018] Further, in step (2), the cross-linking agent is one or more of divinylbenzene, divinylnaphthalene, neopentyl glycol acrylate benzoate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane acrylate benzoate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, and allyl methacrylate, preferably one or two of ethylene glycol di(meth)acrylate and 1,6-hexanediol di(meth)acrylate.

[0019] Furthermore, in step (2), the foaming agent is one or more of isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isododecane, isotridecane, isotetradecane, isopentadecane, isohexadecane, isoheptadecane, isooctane, isooctadecane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cyclododecane, and petroleum ether, preferably one or both of isopentane and isobutane.

[0020] Further, based on the total weight of the monomers, the following weight fractions are included:

[0021]

[0022] Furthermore, in step (4), the preferred polymerization temperature is 45 to 70° C., the preferred pressure is 0.1 to 1 MPa, and the preferred polymerization time is 12 to 24 hours.

[0023] The average particle size of the heat-expandable microcapsules of the present invention is not particularly limited, and the preferred lower limit is 5 μm, and the preferred upper limit is 50 μm. When the particle size is less than 5 μm, the bubbles formed by foaming after reaching the foaming temperature are too small, and the expansion ratio is low. When the particle size is greater than 50 μm, the bubbles formed by foaming after reaching the foaming temperature are too large, and there are problems with strength and toughness. The more preferred lower limit of the above average particle size is 10 μm, and the more preferred upper limit is 45 μm.

[0024] The maximum foaming temperature (T max ) is not particularly limited, but is preferably in the range of 120 to 180° C. When the maximum foaming temperature is lower than 120° C., the heat resistance of the heat-expandable microcapsules is reduced, and they are prone to shrinkage and rupture at high temperatures, resulting in poor foaming stability.

[0025] The pressure-resistant heat-expandable microcapsules obtained by the present invention are of a core-shell structure, with a low-boiling hydrocarbon as a foaming agent and a thermoplastic polymer as an outer shell, and have good pressure resistance. The microcapsules are easily compressed after expansion, and after the pressure is released, the microcapsules are easily restored to their original volume, and can withstand multiple pressurization / decompression without breaking. This is not only very important when the microcapsules are used in shock-absorbing materials, but also very important when the microcapsules are sucked alone or in various mixtures. Therefore, the pressure-resistant heat-expandable microcapsules in the present invention are very suitable for sensitizers for emulsion explosives. DETAILED DESCRIPTION

[0026] The specific implementation steps of the present invention are described in detail through the following examples, which should not be regarded as limiting the scope of the present invention.

[0027] The main raw materials used in the embodiments are as follows:

[0028] Monomers: acrylonitrile, trifluoroethylene, methyl methacrylate, methacrylamide, methacrylonitrile, ethyl methacrylate, 2-fluoromethyl acrylate, N-ethylacrylamide

[0029] Blowing agent: isopentane, isobutane

[0030] Crosslinking agent: 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate

[0031] Dispersion stabilizer: sodium hydroxide, magnesium hydroxide

[0032] Dispersion stabilizing agents: polyvinyl alcohol, polyvinyl pyrrolidone

[0033] Initiator: 2,2'-azobisisobutyronitrile

[0034] The following methods and instruments were used for the analysis of all heat-expandable microcapsules in the examples:

[0035] The average particle size was measured by Zetasizer Nano.

[0036] The foaming performance of the microcapsules was tested by Mettler TMA841, and the foaming performance of the microcapsules was evaluated using a heating rate of 5°C / min and a load of 0.06N. start is the temperature at which expansion begins, T max is the temperature at which maximum expansion is obtained.max When the pressure of 0.06N was applied, the average particle size was measured again using the Zetasizer Nano laser particle size analyzer.

[0037] Example 1

[0038] (1) 500 g of water, 18 g of sodium hydroxide, 10 g of polyvinyl alcohol, and 30 g of sodium nitrite were uniformly mixed to obtain an aqueous phase;

[0039] (2) 40 g of acrylonitrile, 10 g of trifluoroethylene, 20 g of methyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase;

[0040] (3) stirring the oil phase and the water phase to obtain a suspension;

[0041] (4) The obtained suspension is polymerized under an inert atmosphere (here, nitrogen) at 50° C. and a pressure of 0.5 MPa for 15 hours, and then filtered and dried to obtain pressure-resistant thermal expansion microcapsules. The microcapsules are of a core-shell structure, the outer shell is a thermoplastic polymer material, the interior is a foaming agent, and the outer shell thickness is 2-10 μm.

[0042] Example 2

[0043] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (1), 500 g of water, 18 g of magnesium hydroxide, 10 g of polyvinyl alcohol, and 30 g of sodium nitrite were mixed uniformly to obtain an aqueous phase.

[0044] Example 3

[0045] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (1), 500 g of water, 18 g of sodium hydroxide, 10 g of polyvinyl pyrrolidone and 30 g of sodium nitrite were mixed uniformly to obtain an aqueous phase.

[0046] Example 4

[0047] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (1), 500 g of water, 18 g of magnesium hydroxide, 10 g of polyvinyl alcohol, and 30 g of magnesium nitrate were mixed uniformly to obtain an aqueous phase.

[0048] Example 5

[0049] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of ethyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0050] Example 6

[0051] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of methyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0052] Example 7

[0053] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of ethyl methacrylate, 20 g of N-ethylacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0054] Example 8

[0055] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of ethyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobis(2,4-dimethylvaleronitrile), 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0056] Example 9

[0057] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of ethyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of diethylene glycol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0058] Example 10

[0059] Thermally expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that in step (2), 40 g of methacrylonitrile, 10 g of trifluoroethylene, 20 g of ethyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, 20 g of isopentane and 10 g of isobutane were mixed to obtain an oil phase.

[0060] Embodiment 11

[0061] Heat-expandable microcapsules were prepared according to the method of Example 1 (the process and conditions were the same as in Example 1, hereinafter the same), except that: in step (4), the obtained suspension was polymerized under an inert atmosphere at 60° C. and a pressure of 0.5 MPa for 12 hours, and then filtered and dried to obtain pressure-resistant heat-expandable microcapsules.

[0062] The above embodiments are partial implementation methods of the present invention, but the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

[0063] Comparative Example 1

[0064] Thermally expandable microcapsules were prepared according to the method of Example 1, except that in step (1), 500 g of water, 10 g of polyvinyl alcohol and 30 g of sodium nitrite were mixed uniformly to obtain an aqueous phase.

[0065] Comparative Example 2

[0066] Thermally expandable microcapsules were prepared according to the method of Example 1, except that in step (1), 500 g of water, 18 g of sodium hydroxide, 10 g of barium oxalate and 30 g of sodium nitrite were mixed uniformly to obtain an aqueous phase.

[0067] Comparative Example 3

[0068] Thermally expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 40 g of fumaronitrile, 10 g of trifluoroethylene, 20 g of methyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0069] Comparative Example 4

[0070] Heat-expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 40 g of acrylonitrile, 10 g of trifluoroethylene, 20 g of butyl acrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0071] Comparative Example 5

[0072] Thermally expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 20 g of acrylonitrile, 10 g of trifluoroethylene, 20 g of methyl methacrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 30 g of isopentane were mixed to obtain an oil phase.

[0073] Comparative Example 6

[0074] Heat expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 40 g acrylonitrile, 10 g trifluoroethylene, 20 g methyl methacrylate, 20 g methacrylamide, 10 g methyl 2-fluoroacrylate, 5 g 2,2'-azobisisobutyronitrile and 30 g isopentane were mixed to obtain an oil phase.

[0075] Comparative Example 7

[0076] Heat expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 40 g of acrylonitrile, 10 g of trifluoroethylene, 20 g of butyl acrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile and 6 g of 1,6-hexanediol di(meth)acrylate were mixed to obtain an oil phase.

[0077] Comparative Example 8

[0078] Thermally expandable microcapsules were prepared according to the method of Example 1, except that in step (2), 40 g of acrylonitrile, 10 g of trifluoroethylene, 20 g of butyl acrylate, 20 g of methacrylamide, 10 g of methyl 2-fluoroacrylate, 5 g of 2,2'-azobisisobutyronitrile, 6 g of 1,6-hexanediol di(meth)acrylate, and 10 g of isopentane were mixed to obtain an oil phase.

[0079] Comparative Example 9

[0080] Heat-expandable microcapsules were prepared according to the method of Example 1, except that in step (4), the obtained suspension was polymerized under an inert atmosphere at 80° C. and a pressure of 0.5 MPa for 15 hours, and then filtered and dried to obtain pressure-resistant heat-expandable microcapsules.

[0081] Comparing the examples and comparative examples, the results are shown in Tables 1 and 2 below:

[0082] Table 1

[0083]

[0084]

[0085] Table 2

[0086]

[0087] Compared with the comparative examples, the embodiments have better pressure resistance and good foaming performance. Compared with Example 1, Example 2 reduces the amount of dispersion stabilizer, Example 3 changes the type of dispersant, which is not the optimal dispersant, and is unevenly dispersed during the polymerization process, and the pressure resistance and foaming performance are slightly reduced; Example 4 changes the type of inorganic salt, the initial foaming temperature is reduced, and the foaming performance is slightly reduced; Examples 5, 6, and 7 change the type of monomer, and the shell strength of the obtained thermal expansion microcapsules is slightly reduced, and the pressure resistance is slightly poor; Example 8 changes the type of initiator, and the particle size of the obtained thermal expansion microcapsules is reduced; Example 9 changes the type of crosslinking agent, the polymer shell strength is reduced, and the pressure resistance is reduced; Example 10 changes the type of foaming agent, and the initial foaming temperature is reduced; Example 11 changes the polymerization temperature and time, and thermal expansion microcapsules with good pressure resistance can also be obtained.

[0088] From the comparative examples, comparative example 1 removed the dispersion stabilizer, and comparative example 2 changed the type of dispersion stabilizer, resulting in uneven dispersion during the polymerization process and reduced pressure resistance; comparative examples 3 and 4 changed the type of monomers, which were non-preferred monomers, and the pressure resistance of the obtained microcapsules became poor, and even broke after pressure was applied; comparative example 5 reduced the amount of nitrile monomers, which was not the preferred amount, and the strength of the obtained microcapsule polymer shell was reduced, and the pressure resistance was significantly reduced; comparative example 6 removed the cross-linking agent, resulting in poor rigidity of the polymer shell and poor pressure resistance; comparative example 7 did not add a foaming agent, and comparative example 8 reduced the amount of foaming agent, which was not the preferred amount, and foaming was impossible or the foaming performance was very poor; comparative example 9 changed the polymerization temperature and time, which was not the preferred temperature and time, resulting in a low microcapsule molding rate, poor pressure resistance and foaming performance.

[0089] The pressure-resistant heat-expandable microcapsules of the present invention can be used as sensitizers for emulsion explosives. The unfoamed pressure-resistant heat-expandable microcapsules prepared in Example 1 were mixed with Mobil 32# engine oil at a mass ratio of 1:0.3 and heated at 180°C for 5 minutes for foaming. 5 kg of emulsified matrix (temperature 85-90°C) produced by the high-temperature sensitization production line of Jiangsu Maoheng Chemical Company was taken, 20 g of the foamed microcapsules were added, and mixed and sensitized in a mixer to obtain emulsion explosives. The explosion performance of the emulsion explosives was tested, with an explosion velocity of 5000-5200 m / s, a sympathetic detonation distance of 7 cm, and a force of 18.2 mm.

Claims

1. A method for preparing pressure-resistant heat-expandable microcapsules, characterized in that The following steps are involved: 1) mixing a dispersion medium, an inorganic salt, a dispersion stabilizer, and a dispersion stabilization aid to obtain an aqueous phase; 2) mixing monomers, initiators, crosslinking agents and foaming agents to obtain an oil phase; 3) stirring the oil phase and the water phase to obtain a suspension; 4) The obtained suspension is polymerized under an inert atmosphere at 40-80° C. and a pressure of 0.01-1 MPa for 10-25 hours, and then filtered and dried to obtain pressure-resistant heat-expandable microcapsules.

2. The method for preparing pressure-resistant thermal expansion microcapsules according to claim 1, characterized in that: The thermal expansion microcapsule comprises a thermoplastic shell and a foaming agent wrapped in the thermoplastic shell.

3. The method for preparing pressure-resistant heat-expandable microcapsules according to claim 1, characterized in that: In step (1), the dispersion medium is water In step (1), the inorganic salt is one or more of sodium chloride, sodium nitrate, sodium nitrite, potassium chloride, magnesium chloride, calcium chloride, calcium nitrate, and magnesium nitrate; In step (1), the dispersion stabilizer is one or more of salts, metal oxides and metal hydroxides of one or more of metal magnesium, manganese, calcium, sodium and zinc; In step (1), the dispersion stabilization aid is one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene oxide, calcium phosphate, and barium sulfate.

4. The method for preparing pressure-resistant heat-expandable microcapsules according to claim 1, characterized in that: In step (2), the monomer is one or more of acrylonitrile monomers, ethylene monomers, acrylate monomers, acrylamide monomers, and fluorine-containing acrylate monomers.

5. The method for preparing pressure-resistant thermal expansion microcapsules according to claim 1, characterized in that: The monomers in step (2) include the following components in parts by weight:

6. The method for preparing pressure-resistant heat-expandable microcapsules according to claim 4 or 5, characterized in that: In step (2), the acrylonitrile monomer is one or more of acrylonitrile and methacrylonitrile; the ethylene monomer is one or more of vinylidene chloride and trifluoroethylene; the acrylate monomer is one or two of methyl methacrylate, ethyl methacrylate and butyl methacrylate; the acrylamide monomer is one or more of acrylamide, methacrylamide, N-ethylacrylamide and N,N-dimethylacrylamide; and the fluorine-containing acrylate monomer is methyl 2-fluoroacrylate.

7. The method for preparing pressure-resistant heat-expandable microcapsules according to claim 1, characterized in that: In step (2), the initiator is one or more of diacyl peroxides such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), diisopropyl peroxydicarbonate, di-sec-butyl peroxide, di(2-ethylhexyl) peroxydicarbonate, lauroyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide; In step (2), the crosslinking agent is one or more of divinylbenzene, divinylnaphthalene, neopentyl glycol acrylate benzoate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane acrylate benzoate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, and allyl methacrylate; In step (2), the foaming agent is one or more of isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isododecane, isotridecane, isotetradecane, isopentadecane, iso160,000, isoheptadecane, isooctadecane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cyclododecane, petroleum ether, and the like.

8. The method for preparing pressure-resistant heat-expandable microcapsules according to claim 1, 5 or 7, characterized in that: Based on the total weight of the monomers as 1 part, other materials in the suspension include the following weight fractions:

9. The pressure-resistant heat-expandable microcapsules prepared by the method for preparing pressure-resistant heat-expandable microcapsules according to any one of claims 1 to 8.

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